On-Site Wastewater Treatment and Disposal Systems - Forced ...

DE SIGN MANUAL 

WASTEWATER TREATMENT 

AND DISPOSAL SYSTEMS 

ENVIRONMENTAL PROTECTION AGENCY 

Office of Water Program 

Office of Research and 

Municipal Research Laboratory 

October

NOTICE 

The mention of trade names or commercial products in this publication is 

for illustration purposes and does not constitute endorsement or 

on for use by the Environmental Protection Agency.

FOREWORD 

Rural and suburban communities are confronted with problems that are 

unique to their size and population density, and are often unable to 

superimpose solutions typically applicable to larger urban areas. A 

good example of such problems is the provision of wastewater services. 

In the past, priorities for water pollution control focused on the 

cities, since waste generation from these areas was most evident. In 

such hi development, the traditional sanitary 

approach was to construct a network of sewers to convey wastewater to a 

central location for treatment and disposal to surface waters. Since a 

large number of users existed per unit length of sewer line, the costs 

of construction and operation could be divided among many people, thus 

the burden on each user a ti ow. 

Within the past several decades, migration of the population from cities 

to suburban and rural areas has been significant. With this shift came 

the problems of providing utility services to the residents. 

Unfortunately, in cases, solutions to wastewater problems in urban 

areas have been applied to rural communities. With the advent of 

federal programs that de grants for construction of wastewater 

facilities, sewers and centralized treatment plants were constructed in 

these low- density rural settings. In many cases the cost of operating 

and maintaining such facilities impose severe economic burdens on the 

communi ties. 

though wastewater treatment and systems single homes 

have been used for many years, they have often been considered an 

i 

or temporary sol uti on sewers d be constructed. 

However, research has demonstrated that such systems, if constructed and 

properly, can provide a reliable and efficient means of 

wastewater treatment and at ow cost. 

s document des technical on on wastewater 

treatment and disposal systems. It does not contain standards for those 

systems, nor does it contain rules or regulations pertaining to 

systems. 

The intended audience for this manual includes those involved in the 

design, construction, operation, maintenance, and regulation of 

wastewater systems.

OW L S 

There were three groups of participants involved in the preparation of 

this manual : (1) the contractor- authors, the contract supervisors, 

and (3) the technical reviewers. The was written by personnel 

from Engineers and Rural Systems Engineering Contract 

was by Protection Agency 

personnel from the Municipal Construction Division in Washington, 

and from the Municipal Environmental Research Laboratory in Cincinnati 

Ohio. The technical reviewers were experts in certain areas of 

waste treatment and disposal, and included professors, health officials, 

consultants, and government officials. Each provided technical review 

of a section or sections of the report. The membership of each group is 

bel ow. 

CONTRACTOR-AUTHORS: 

Curtis 

William 

Schmidt, 

Senior Authors: Ernest Project Manager, 

Richard Otis, 

Contributing Authors: David 

Robert 

E. Jerry Tyler, 

d E. Stewart, James Converse, 

CONTRACT SUPERVISORS: 

Project Officers: Robert Southworth, Washington, 

Robert Cincinnati, Ohio 

ewers: James o 

s o 

Reed, 

TECHNICAL REVIEWERS: 

Michael Hansel Minnesota Pollution Control Agency 

Roger University of Minnesota 

Jack 

Hurt, Lexington, Kentucky 

William Lake County Health Department, Illinois 

Rein University of Connecticut 

Gary Department of Social Health Services 

North Carolina State University 

John Clayton County Health Department, Virginia 

am a State 

Elmer Jones Department of Agriculture 

Bennett University of Colorado 

Harry Pence Vi Polytechnic Institute 

Briar Cook Department of Agriculture, Forest Service 

Ontario Ministry of the Environment (Retired) 

Michael Illinois State Department of Public Health 

John Fancy John Fancy, Maine

Chapter 

CONTENTS 

Page 

FOREWORD 

ACKNOWLEDGEMENTS, V 

CONTENTS vi i 

LIST OF FIGURES 

LIST OF TABLES 

INTRODUCTION 

Background 

Purpose 

Scope 

STRATEGY FOR SYSTEM DESIGN 

Introduction 

Onsite System Design Strategy 

SITE EVALUATION PROCEDURES 

Introduction 

Disposal 

Site Evaluation Strategy 

References 

WASTEWATER CHARACTERISTICS 

on 

Residential Wastewater Characteristics 

Nonresidential Wastewater Characteristics 

Predicting Wastewater Characteristics 

References 

WASTEWATER MODIFICATION 

on 

Water Conservation and Wastewater ow Reduction 

Pollutant Mass Reduction 

Onsite Containment Holding Tanks 

Reliability 

Impacts on Onsite Treatment and Disposal 

Practices 

References 

V

Chapter 

CONTENTS 

ON SITE TREATMENT METHODS 

Introduction 

Septic Tanks 

Intermittent Sand Filters 

Aerobic Treatment Units 

si 

on 

Removal 

Waste Segregation and e Systems 

References 

DISPOSAL METHODS 

Introduction 

Subsurface Absorption 

Evaporation Systems 

Outfall to Surface Waters 

References 

APPURTENANCES 

Introduction 

Grease Traps 

Dosing Chambers 

Flow Diversion Methods for Alternating Beds 

References 

RESIDUALS DISPOSAL 

Introduction 

dual s Characteristics 

dual s i Option 

Ultimate Disposal of 

References 

MANAGEMENT OF SYSTEMS 

Introduction 

Theory of Management 

Types of Management ties 

Management Program Functions 

References 

APPENDIX Soil Properties and Soil -Water Relationships 

GLOSSARY 

vi 

Page

Number 

FIGURES 

Wastewater Management 

System Design Strategy 

Potential Evaporation Versus Mean Annual 

pi on 

Example of a Portion of a Soil Map as Published 

in a Detailed Soil Survey (Actual Size) 

Translation of Typical Soil Mapping Unit Symbol 

Plot Plan Showing Soil Series Boundaries from 

Soil Survey Report 

Plan Surface Features 

Landscape Positions 

Methods of Expressing Land Slopes 

Preparation of Sample for d Determi nation 

of Texture 

Texture Determi tion by Hand: Physical 

Appearance o f Various Soil Textures 

Comparison of Ribbons and Casts of Sandy Loam and 

Clay (Ribbons Above, Casts Below) 

e Procedure for Collecting Soil Pit 

Observation Informati on 

Types of Soil Structure 

Typical Observation Well for Determining Soil 

Saturation 

Construction of a 

Percolation Test Data Form 

a tion of s and Si Informati on 

(Informati on Includes Topographic, Survey, 

ope and Soil Pit Observations) 

vi 

Page

FIGURES (continued) 

Number Page 

Frequency on for Average Daily 

Water Flows 

Peak Discharge Versus Units Present 

Strategy for Wastewater Characteristics 

e Strategies for Management of Segregated 

Human Wastes 

Example Strategies for Management of Residential 

ow Reduction Effects on Pollutant Concentrations 

Typical c Tank et Structures to Mi 

Suspended Soli n 

Septic Tank Scum and Sludge Clear Spaces 

Typical Two-Compartment c Tank 

Four Precast Rei Concrete Septic Tanks 

Combined into One Unit for Large Flow 

on 

Typical Buried Intermittent Filter Installation 

Typical Free Access Intermi 

a ti on Tank 

By-Pass for 

Intermi System 

Aerobic and Anaerobic Decomposition Products 

Examples of Extended Aeration Package Plant 

Configurations 

Examples of Fixed Film Package Plant Configurations 

Stack Feed 

vi

FIGURES 

Number Page 

ne Saturator 

Sample Contact Chamber 

Typical si on t 

Typical Trench System 

Typical Bed System 

i Chamber 

on Systems 

Trench System with version Val 

Provision of a Reserve Area Between Trenches of 

the Initial System on a Sloping Site 

Trench System Installed to Overcome a Shallow Water 

Table or Restrictive Layer 

Typical on Pi 

Backhoe Bucket 

Removable Raker Teeth 

Methods of on.Field.Rehabilitation 

Seepage Pit Cross Section 

Typical Mound Systems 

Schematic of a Mound System 

Proper Orientation of a Mound System on a Complex 

ope 

Mound 

Tiered Mound System 

n ti to Intercept Laterally Perched 

Water Table Caused by a Shallow, Impermeable Layer

FIGURES 

Number Page 

Vertical Drain to Intercept Laterally 

Perched Water Table Caused by a Shallow, 

Thin, Impermeable Layer 

Underdrains Used to Lower Water Table 

Typical El s System 

Si e ne on Network 

Drop Box 

Loop 

on Box Network 

on Network 

on Network 

ne on Network 

Central d Network 

End d on Network 

Lateral Detail Tee to Tee Construction 

Lateral Detail Staggered Tees or Cross 

on 

Required Lateral Pipe Diameters for Various e 

Diameters, Hole and Lateral Lengths 

(for c Pipe Only) 

Recommended d Diameters for Various d 

Lengths, Number of Lateral and Lateral 

Discharge Rates (for Plastic Pipe Only) 

Nomograph for the Mi Dose Volume 

for a Given Lateral Diameter, Lateral Length, 

and Number of Laterals 

on Network for Example 

on Network for e 

Schematic of a Chamber 

X

FIGURES 

Number Page 

Use of Metal Holders for the Laying of Flexible 

Plastic Pipe 

Cross Section of Typical ET Bed 

Curve for Establishing Permanent Home Loading Rate 

for Boulder, Colorado Based on Winter Data, 

Typical on Lagoon for 

Small Instal 

e-Compartment Grease Trap 

Typical Dosing Chamber with Pump 

Level Control Switches 

Typical Chamber Si phon 

version Val 

Top View of Diversion Box Utilizing a Treated 

Wood Gate 

Section View of Diversion Box Utilizing 

Adjustable El s 

A - 1 Names and Size Limits of Practical - Size Classes 

According to Six Systems 

A-2 Textural e Textural Classes 

of the (Illustrated for a Sample Containing 

Sand, and Clay) 

A- 3 Schematic Diagram of a Landscape and Different 

s e 

A-4 Upward Movement by Capillarity in Glass Tubes as 

Compared with Soils 

A-5 Soil Moisture Retention for Four Different Soil 

Textures 

xi

FIGURES (continued) 

Number Page 

A- 6 c vi Versus 

on 

A- 7 Schematic Representation of Water Movement Through 

a Crusts of Resistances 

xi i

Number 

TABLES 

Selection of Disposal Methods Under Various 

Site 

Suggested Site on Procedure 

Soil Limitations Ratings Used by for Septic 

an el 

Soil Survey Report Information for Parcel in 

Figure 

Textural of Mi s 

Grades of Soil Structure 

on of Mottles 

Estimated c of 

Head Percolati on Test Procedure 

Summary of Average Daily Residential Wastewater 

ow s 

denti Water Use by 

of denti Wastewater 

Pollutant Contributions of Major Residential 

Wastewater 

Pol Concentrations of Major Residential 

Wastewater Fractions 

Typical Wastewater from Commercial Sources 

Typical Wastewater from Institutional 

Sources 

Typical Wastewater Flows from Recreational Sources 

per 

Example Wastewater ow on Methods 

xi 

Page

TABLES 

Number Page 

Wastewater ow Reduction Water Carriage 

Toilets and Systems 

Wastewater ow 


and Systems 


and Systems 


Reuse Systems 

e Pol 

Reduction 

Reduction 

Carriage 

Devices 

Reduction Miscellaneous Devices 

Reduction Wastewater Recycle and 

Mass on Methods 

ti 

n the Instal on 

and Operation of Tanks 

Potential Impacts of Wastewater Modification on 

Practices 

Summary of Effluent Data from Various 

Intermittent 

Intermi 

Septic Tank 

Septic Tank qui d Volume Requirements 

Location of Top and Bottom of Outlet Tee or 

Performance of Buried Intermittent 

Septic Tank Effluent 

Performance of Free Access 

Performance of 

Design Criteria for Intermi 

Design Criteria for Free Access Intermittent 

Design Criteria for Intermittent 

on and 

Intermittent 

xi v 

Baffle 

for Buried

Number 

TABLES (continued) 

Operati on and Requirements for Free 

Access Intermittent 

Operati on and Requirements for 

Summary of Effluent Data from Various Aerobic Unit 

el d 

Typical Operating Parameters for Extended 

ti on Systems 

Suggested Maintenance for Extended Aeration 

Package Plants 

Operational ems Extended Aeration Package 

Plants 

Typical Operating Parameters for Fixed Film 

stems 

Suggested Maintenance for Fixed Film Package 

ants 

Operational Problems Fixed Film Package Plants 

Selected Potential si for 

tion 

Halogen 

ne Demand of Selected c Wastewaters 

Performance of Halogens and Ozone at 25°C 

Hal Dosage deli 

Dosage for Selected 

Control 

Potential Phosphorus Removal Options 

Phosphorus Adsorption Estimates for Selected 

Natural s 

Page

TABLES 

r Page 

Site Criteria for Trench and Bed Systems 

Recommended Rates of Wastewater on for 

Trench and Bed Bottom Areas 

Typical Dimensions for Trenches and Beds 

Frequencies for Textures 

Methods of Wastewater Application for Various 

System Designs and ti 

Si Areas of Circular Seepage Pits 

Site Criteria for Mound Systems 

Commonly Used Fill Materials and their Design 

on Rates 

Dimensions for Mound Systems 

Area 

on Rates for Mound Basal 

Methods for Various Si 

on Networks for Various System Designs 

and on Methods 

Discharge Rates for Various Sized Holes at Various 

Pressures 

Friction Loss in Schedule Plastic Pipe, 

Pipe Materials for zed on 

Networks 

Sample Water Balance for Evaporation Lagoon Design 

Recommended Ratings for Commercial Grease Traps 

dual s Generated from Wastewater Systems

TABLES (continued) 

Number Page 

of Domestic 

Indicator and Pathogen Concentrations 

in Domestic 

Land Disposal for 

Independent Treatment ti 

tag e Treatment at s Treatment a n 

Site on and System Design 

Instal Functions 

on and Functions 

tion 

A- 1 Department of Agriculture Si mi for 

Separates 

A Types and Classes of Soil Structure

1.1 Background 

CHAPTER 1 

INTRODUCTION 

Approximately 18 million housing units, or 25% of all housing units in 

the United States, dispose of their wastewater using onsite wastewater 

treatment and disposal systems. These systems include a variety of components 

and configurations, the most common being the septic tank/soil 

absorption system. The number of onsite systems is increasing, with 

about one-half million new systems being installed each year. 

The first onsite treatment and disposal systems were constructed by 

homeowners themselves or by local entrepreneurs in accordance with de- 

sign criteria furnished by federal or state health departments. usu- 

ally, a septic tank followed by a soil absorption field was installed. 

Trenches in the soil absorption system were dug wide enough to accommo- 

date open-jointed drain tile laid directly on the exposed trench bottom. 

Some health departments suggested that deeper and wider trenches be used 

in "dense" soils and that the bottom of those trenches be covered with 

coarse aggregate before the drain tile was laid. The purposes of the 

aggregate were to provide a porous media through which the septic tank 

effluent could flow and to provide storage of the liquid until it could 

infiltrate into the surrounding soil. 

It has been estimated that only 32% of the total land area in the United 

States has soils suitable for onsite systems which utilize the soil for 

final treatment and disposal of wastewater. In areas where there is 

pressure for development, onsite systems have often been installed on 

land that is not suitable for conventional soil absorption systems. 

Cases of contaminated wells attributed to inadequately treated septic 

tank effluent, and nutrient enrichment of lakes from near-shore develop- 

ment are examples of what may occur when a soil absorption system is 

installed in an area with unsuitable soil or geological conditions. 

Alarmed by the potential health hazards of improperly functioning sys- 

tems, public health officials have continually sought methods to improve 

the desSgn and performance of onsite systems. 

Unfortunately, the great increases in population have exacerbated the 

problems associated with onsite systems. The luxury of vast amounts of 

land for homesites is gone; instead, denser housing in rural areas is 

more common. 

1

In many areas, onsite systems have been plagued by poor public accep- 

tance; feelings that those systems were second rate, temporary, or fail- 

ure prone. This perspective contributed to poorly designed, poorly con- 

structed, and inadequately maintained onsite systems. 

Recently, the situation has begun to change. Federal, state, and local 

governments have refocused their attention on rural wastewater disposal 

and, more particularly, on wastewater systems affordable by the rural 

population. Onsite systems are now gaining desired recognition as a 

viable wastewater management alternative that can provide excellent, 

reliable service at a reasonable cost, while still preserving environ- 

mental quality. Federal and many state and local governments have 

initiated public education programs dealing with the technical and 

administrative aspects of onsite systems and other less costly waste- 

water handling alternatives for rural areas. 

In this time of population movements to rural and semirural areas, high 

costs of centralized sewage collection and treatment, and new funding 

incentives for cost and energy saving technologies, those involved with 

rural wastewater management need more information on the planning, de- 

sign, construction, and management of onsite systems. This process de- 

sign manual provides primarily technical guidance on the design, con- 

struction, and maintenance of such systems. 

1.2 Purpose 

This document provides information on generic types of onsite wastewater 

treatment and disposal systems. It contains neither standards for those 

systems nor rules and regulations pertaining to onsite systems. The de- 

sign information presented herein is intended as technical guidance re- 

flective of sound, professional practice. The intended audience for the 

manual includes those involved in the design, construction, operation, 

maintenance, and regulation of onsite systems. 

Technologies discussed in this manual were selected because of past 

operating experience and/or because of the availability of information 

and performance data on those processes. Because a particular waste- 

water handling option is not discussed in this manual does not mean that 

it is not acceptable. All available technologies should be considered 

when planning wastewater management systems for rural and suburban com- 

munities. 

Groundwater and surface water pollution are major environmental consid- 

erations when onsite systems are used. All wastewater treatment and 

disposal systems must be designed, constructed, operated, and maintained 

2

to prevent degradation of both groundwater and surface water quality. 

For onsite systems designed and constructed using Environmental Protec- 

tion Agency funds, all applicable regulations must be complied with, 

including requirements for disposal to groundwaters (40 - FR 6190, February 

11, 1976). 

This manual is only a guide. Before an onsite system is designed and 

constructed, appropriate local or state authorities should be contacted 

to determine the local design requirements for a particular system. 

1.3 Scope 

This manual includes: 

1. A strategy for selecting an onsite system 

2. A procedure for conducting a site evaluation 

3. A summary of wastewater characteristics 

4. A discussion of waste load modification 

5. A presentation of generic onsite wastewater treatment methods 

6. A presentation of generic onsite wastewater disposal methods 

7. A discussion of appurtenances for onsite systems 

8. An overview of residuals characteristics and treatment/disposal 

alternatives 

9. A discussion of management of onsite systems 

The emphasis of this manual is on systems for single dwellings and small 

clusters of up to 10 to 12 housing units. Additional factors must be 

considered for clusters of systems serving more than 10 to 12 housing 

units. A brief discussion of onsite systems for multi-home units and 

commercial/institutional establishments is also presented, when the 

system designs differ significantly from those for single dwellings.

2.1 Introduction 

CHAPTER 2 

STRATEGY FOR ONSITE SYSTEM DESIGN 

A wide variety of onsite system designs exist from which to select the 

most appropriate for a given site. The primary criterion for selection 

of one design over another is protection of the public health while pre- 

venting environmental degradation. Secondary criteria are cost and ease 

of operating and maintaining the system. The fate of any residuals re- 

sulting from the treatment and disposal system must be considered in the 

selection process. 

Figure 2-1 summarizes wastewater management options for onsite systems. 

Because of the wide variety, selection of the system that prevents pub- 

lic health hazards and maintains environmental quality at the least cost 

is a difficult task. The purpose of this chapter is to present a stra- 

tegy for selecting the optimum onsite system for a particular environ- 

ment. At each step, the reader is referred to the appropriate chapters 

in the manual for site evaluation, and subsequent system design, con- 

struction, operation and maintenance, and residuals disposal. 

2.2 Onsite System Design Strategy 

Traditionally, subsurface soil absorption has been used almost exclu- 

sively for onsite disposal of wastewater because of its ability to meet 

the public health and environmental criteria without the necessity for 

complex design or high cost. A properly designed, constructed, and 

maintained subsurface absorption system performs reliably over a long 

period of time with little attention. This is because of the large 

natural capacity of the soil to assimilate the wastewater pollutants. 

Unfortunately, much of the land area in the United States does not have 

soils suited for conventional subsurface soil absorption fields. If 

soil absorption cannot be utilized, wastewater also may be safely dis- 

posed of into surface waters or evaporated into the atmosphere. How- 

ever, more complex systems may be required to reliably meet the public 

health and environmental criteria where these disposal methods are used. 

Not only are complex systems often more costly to construct, but they 

are also more difficult and costly to maintain. Therefore, the onsite 

system selection strategy described here is based on the assumption that 

4

FIGURE 2-l 

ONSITE WASTEWATER MANAGEMENT OPTIONS 

PRETREATMENT 

(Ch. 6) 

- Septic Tank 

- Aerobic Unit 

c mm --___- HOLDING’ 

TANK 

- Trenches 

- Beds 

- Pits 

- Mounds 

- Fill Systems 

- Artificially Drained 

Systems 

\ t 

. 

FURTHER TREATMENT’ 

L ------------------..---. I - Aerobic Unit 

- Granular Filter 

- Nutrient Removal 

- Disinfection

subsurface soil absorption is the preferred onsite disposal option be- 

cause of its areater reliabilitv with a minimum of attention. Where the 

site characterlstlcs are unsuitable for conventional subsurface soil 

absorption systems, other subsurface soil absorption systems may be 

possible. Though these other systems may be more costly to construct 

than systems employing surface water discharge or evaporation, their 

reliable performance under a minimum of supervision may make them the 

preferred alternative. Figure 2-2 illustrates the onsite system design 

strategy discussed in this chapter. 

2.2.1 Preliminary System Screening 

The first step in the design of an onsite system is the selection of the 

most appropriate components to make up the system. Since the site char- 

acteristics constrain the method of disposal more than other components-, 

the disposal component must be selected first. Selection of wastewater 

modification and treatment components follow. To select the disposal 

method properly, a detailed site evaluation is required. However, the 

site characteristics that must be evaluated may vary with the disposal 

method. Since it is not economical nor practical to evaluate a site for 

every conceivable system design, the purpose of this first step is to 

eliminate the disposal options with the least potential so that the de- 

tailed site evaluation can concentrate on the most promising options. 

To effectively screen the disposal options, the wastewater to be treated 

and disposed must be characterized, and an initial site investigation 

made. 

2.2.1.1 Wastewater Characterization 

The estimated daily wastewater volume and any short- or long-term 

variations in flow affect the size of many of the system components. In 

addition, the concentrations of various constituents can affect the 

treatment and disposal options chosen. Characteristics are presented in 

Chapter 4 for wastewater from residential dwellings as well as from 

commercial operations. 

2.2.1.2 Initial Site Evaluation 

All useful information about the site should be collected. This may be 

accomplished by client contact, a review of available published resource 

information and records, and an initial site visit. Client contact and 

a review of published maps and reports should provide information re- 

garding the soils, geology, topography, climate, and other physical 

6

FIGURE 2-2 

ONSITE SYSTEM DESIGN STRATEGY 

Initial 

Site 

Evaluation 

(Sec. 3.3.1, 3.3.2) 

7 

Design System 

l Treatment (Ch. 5,6.8) 

0 Disposal (Ch. 7) 

0 Residuals (Ch. 9) 

Selection of 

Treatment 

Component(s) 

(Figure 2-1) 

Selection of 

Disposal Option

features of the site (See 3.3.1 and 3.3.2). An initial site visit 

should also be made, and should include a visual survey of the area and 

preliminary field testing, if required, with a hand auger (See 3.3.3). 

From this site visit, general site features such as relative soil perme- 

ability, depth and nature of bedrock, depth to water table, slope, lot 

size, and landscape position should be identified. Sources of informa- 

tion and evaluation procedures for site evaluation are detailed in 

Chapter 3. 

2.2.1.3 Preliminary Screening of Disposal Options 

From the wastewater characteristics 

this step, a preliminary screening 

and site information 

of the disposal options 

gathered in 

can be made 

using Table 2-l. This table indicates the onsite disposal options that 

otentially may work for the given site constraints. The potentially 

-!-ailn 

lsposal options are identified by noting which ones perform 

effectively under all the given site constraints. Note that with suffi- 

cient treatment and presence of receiving waters, surface water dis- 

charge is always a potential disposal option. 

As an example, suppose a site for a single-family home has the following 

general characteristics: 

1. Very rapidly permeable soil 

2. Deep bedrock 

3. Shallow water table 

4. Five to 15 percent slope 

i: 

Large lot 

Low evaporation potential 

From Table 2-1, the disposal options most applicable to the example site 

constraints are: 

1. Mounds 

2. Fills 

3. Surface water discharge 

The design sections in Chapter 7 wouid be consulted at this point to 

determine the specific characteristics to be evaluated at the site in 

order to select the most feasible disposal options. 

8

TABLE 2-l 

SELECTION OF DISPOSAL METHODS UNDER VARIOUS SITE CONSTRAINTS 

Site Constraints 

Depth to Bedrock 

Sot1 Permeabiltty 

5mall 

-01 

Size 

- 

Depth to 

Water table 

- 

15% 

3-5% 

lee, 

= 

X 

ihallow 

Deep 

Shallow 

and 

Nonporous 

;hallow 

tnd 

‘orous 

SIOW- 

Very Slow 

Rapid- 

Moderate 

Very 

Rapid 

Method 

= 

X 

X 

X 

X 

X 

X 

X 

X 

Trenches 

Beds 

X 

X 

X 

X 

X 

X 

X 

X 

Ptts 

X 

Mounds 

X 

X 

X 

X 

X’ 

Fill Systems 

X’ 

X 

X 

X 

X 

Sand-Lrned 

Trenches or 

Beds 

X’ 

X 

X 

X 

Artifrcrally 

Drarned 

Systems 

X 

X 

X 

X 

Evaporation 

lnftltration 

Lagoons 

X 

X 

X 

X 

Evaporation 

Lagoons 

(lined)4,5 

X 

X 

X 

X 

ET Beds 

or Trenches 

(lined) 4,5 

X 

X 

X 

X 

X 

ETA Beds 

or Trenches4 

- 

- 

I Only where surface soil can be stripped to expose sand or sandy loam maternal. 

2 Construct only during dry soil conditions. Use trench configuration only. 

3 Trenches only. 

X means system can function effectively 

with that constratnt. 

4 Flow reduction suggested. 

5 High Evaporation potential required. 

6 Recommended for south-facing slopes only.

2.2.2 System Selection 

With the potentially feasible disposal options in mind, a detailed site 

evaluation is performed. The information collected is used to identify 

the system options that meet the public health and environmental cri- 

teria. If more than one system is feasible, final selection is based on 

results of a cost effective analysis. Local codes should be consulted 

to determine which onsite treatment and disposal methods are permitted 

in the area. 

2.2.2.1 Detailed Site Evaluation 

A careful, detailed site evaluation is needed to provide sufficient 

information to select the most appropriate treatment and disposal system 

from the potentially feasible system options. The evaluation should be 

performed in a systematic manner so as to insure that the information 

collected is useful and in sufficient detail. A site evaluation proce- 

dure is suggested in Chapter 3, including descriptions of the tests and 

observations to be made. This procedure is based on the assumption that 

subsurface soil absorption is the preferred method of disposal. If sub- 

surface absorption cannot be used, techniques are explained for evaluat- 

ing the suitability of a site for surface water discharge or evapora- 

tion. 

2.2.2.2 Selection of Most Appropriate System 

The disposal option selected after the detailed site evaluation dictates 

the ,quality of the wastewater required prior to disposal. If suitable 

soils exist onsite to employ one of the subsurface soil absorption meth- 

ods of disposal, the quality of the wastewater applied need not be high 

due to the assimilative capacity of the soil. Where suitable soils do 

not exist onsite, other methods of disposal that require a higher qual- 

ity of wastewater may be necessary. These wastewater quality require- 

ments are established during the site evaluation (Chapter 3). Waste- 

water reduction and treatment options are selected to meet the required 

wastewater quality. 

Altering the characteristics of the wastewater generated can have a 

major impact on the design of the treatment and disposal system. 

Alteration can be beneficial in reducing the sire or complexity of the 

system. Chapter 5 describes a variety of wastewater reduction options. 

10

Chapter 6 provides detailed information regarding the design, 

construction and operation of various treatment options. Selection of 

the most appropriate treatment option is based on performance and cost. 

Various onsite systems may be synthesized from the data presented in 

Chapters 5 and 6. As an example of the synthesis of treatment and 

disposal systems following the detailed site evaluation, assume that all 

three disposal options selected in 2.2.1.3 proved to be feasible. 

Examination of the first two disposal options indicates that only 

minimal pretreatment may be required. Thus, two systems might be: 

1. Septic tank - mounds 

2. Septic tank - fill 

If groundwater quality is a constraint, however, it may be necessary to 

develop other systems. Thus, if nitrogen discharges from the disposal 

system to the groundwater must be controlled, the two treatment-disposal 

systems may be revised to include the following: 

1. Septic tank - mound - denitrification 

2. In-house toilet segregation/graywater - septic tank - fill 

Note that a variety of other systems may be developed as well. The 

other disposal option listed in 2.2.1.3 is surface water discharge. 

Several treatment options exist if the wastewater is disposed of by 

discharge to surface waters. Filtration and disinfection may be 

required as part of those treatment options, depending on the water 

quality requirements of the appropriate regulatory agency. 

Residuals produced from the treatment processes also require safe 

disposal. This must be considered in the selection of the treatment and 

disposal system. Chapter 9 provides information regarding the 

character, required treatment, and methods of ultimate disposal of 

various residuals produced. 

2.2.3 System Design 

Once all the components are selected, design of the system follows. 

Chapters 5, 6, 7, 8, and 9 should be consulted for design information. 

11

2.2.4 Onsite System Management 

Past experience has shown that onsite management districts have many 

. benefits, including improved site selection, system design, construc- 

tion, and operation and maintenance. Management districts also facili- 

tate the use of more complex systems or larger systems servicing a clus- 

ter of several homes. These districts can take many forms with varying 

powers. Chapter 10 provides an overview of management options for on- 

site systems. 

12


CHAPTER 3 

SITE EVALUATION PROCEDURES 

The environment into which the wastewater is discharged can be a valu- 

able part of an onsite wastewater and disposal system. If utilized 

properly, it can provide excellent treatment at little cost. However, 

if stressed beyond its assimilative capacity, the system will fail. 

Therefore, careful site evaluation is a vital part of onsite system 

design. 

3.2 Disposal Options 

In general, facilities designed to discharge partially treated waste- 

water to the soil for ultimate disposal are the most reliable and least 

costly onsite systems. This is because little pretreatment of the 

wastewater is necessary before application to the soil. The soil has a 

very large capacity to transform and recycle most pollutants found in 

domestic wastewaters. While the assimilative capacity of some surface 

waters also may be great, the quality of the wastewater to be discharged 

into them is usually specified by local water quality regulatory 

agencies. 

To achieve the specified quality may require a more costly treatment 

system. On the other hand, evaporation of wastewater into the atmo- 

sphere requires little wastewater pretreatment, but this method of dis- 

posal is severely limited by local climatic conditions. Therefore, the 

soil should be carefully evaluated prior to the investigation of other 

receiving environments. 

3.2.1 Wastewater Treatment and Disposal by Soil 

Soil is the weathered and unconsolidated outer layer of the earth's 

surface. It is a complex arrangement of primary mineral and organic 

particles that differ in composition, size, shape, and arrangement. 

Pores or voids between the particles transmit and retain air and water. 

Since it is through these pores that the wastewater must pass to be 

absorbed and treated, their characteristics are important. These are 

13

determined largely by the physical properties of the soil. Descriptions 

of some of the more important physical properties appear in Appendix A. 

The soil is capable of treating organic materials, inorganic substances, 

and pathogens in wastewater by acting as a filter, exchanger, adsorber, 

and a surface on which many chemical and biochemical processes may 

occur. The combination of these processes acting on the wastewater as 

it passes through the soil produces a water of acceptable quality for 

discharge into the groundwater under the proper conditions. 

Physical entrapment of particulate matter in the wastewater may be 

responsible for much of the treatment provided by soil. This process 

performs best when the soil is unsaturated. If saturated soil conditions 

prevail, the wastewater flows through the larger pores and receives 

minimal treatment. However, if the soil is kept unsaturated by 

restricting the wastewater flow into the soil, filtration is enhanced 

because the wastewater is forced to flow through the smaller pores of 

the soil. 

Because most soil particles and organic matter are negatively charged, 

they attract and hold positively charged wastewater components and repel 

those of like charge. The total charge on the surfaces of the soil sys- 

tem is called the cation exchange capacity, and is a good measure of the 

soil's ability to retain wastewater components. The charged sites in 

the soil are able to sorb bacteria, viruses, ammonium, nitrogen, and 

phosphorus, the principal wastewater constituents of concern. The 

retention of bacteria and viruses allows time for their die-off or 

destruction by other processes, such as predation by other soil micro- 

organisms (l)(2). Ammonium ions can be adsorbed onto clay particles. 

Where anaerobic conditions prevail, the ammonium ions may be retained on 

the particles. If oxygen is present, bacteria can quickly nitrify the 

ammonium to nitrate which is soluble and is easily leached to the 

groundwater. Phosphorus, on the other hand, is quickly chemisorbed onto 

mineral surfaces of the soil, and as the concentration of phosphorus 

increases with time, precipitates may form with the iron, aluminum, or 

calcium naturally present in most soils. Therefore, the movement of 

phosphorus through most soils is very slow (l)(2). 

Numerous studies have shown that 2 ft to 4 ft (0.6 to 1.2 m) of 

unsaturated soil is sufficient to remove bacteria and viruses to 

acceptable levels and nearly all phosphorus (l)(2). The needed depth is 

determined by the permeability of the soil. Soils with rapid 

permeabilities may require greater unsaturated depths below the 

infiltrative surface than soils with slow permeabilitiers. 

14

3.2.2 Wastewater Treatment and Disposal by Evaporation 

Wastewater can be returned directly to the hydrologic cycle by evapora- 

tion. This has appeal in onsite wastewater disposal because it can be 

used in some areas where site conditions preclude soil absorption or in 

areas where surface water or groundwater contamination is a concern. 

The wastewater can be confined and the water removed to concentrate the 

pollutants within the system. Little or no treatment is required prior 

to evaporation. However, climatic conditions restrict the application 

of this method. 

Evaporation can take place from a free water surface, bare soil, or 

plant canopies. Evaporation from plants is called transpiration. Since 

it is often difficult to separate these two processes on partially bare 

soil surfaces, they are considered as a single process called evapo- 

transpiration (ET). 

If evaporation is to occur continuously, three conditions must be met 

(3). First, there must be a continuous supply of heat to meet the la- 

tent heat requirements of water (approximately 590 cal/gm of water evap- 

orated at 15 Cl. Second, the vapor pressure in the atmosphere over the 

evaporative surface must remain lower than the vapor pressure at the 

surface. This vapor pressure gradient is necessary to remove the mois- 

ture either by diffusion, convection, or both. Third, there must be a 

continuous supply of water to the evaporative surface. The first two 

conditions are strongly influenced by meteorological factors such as air 

temperature, humidity, wind velocity, and solar radiation, while the 

third can be controlled by design. 

Successful use of evaporation for wastewater disposal requires that 

evaporation exceed the total water input to the system. Rates of evap- 

oration decrease dramatically during the cold winter months. In the 

case of evaporative lagoons or evapotranspiration beds, input from pre- 

cipitation must also be included. Therefore, application of evaporation 

for wastewater disposal is largely restricted to areas where evaporation 

rates exceed precipitation rates. These areas occur primarily in the 

southwestern United States (see Figure 3-l). In other areas, evapora- 

tion can be used to augment percolation into the soil. 

Transpiration by plants can be used to augment evaporation in soil-cov- 

ered systems (5)(6), Plants can transpire at high rates, but only dur- 

ing daylight hours of the growing season. During such periods, evapo- 

transpiration rates may ,exceed ten times the rates measured in Class A 

evaporation pans (7)(8)(g). However, overall monthly evaporation rates 

exceed measured evapotranspiration rates. Ratios of evapotranspiration 

to evaporation (as measured from Class A pans) are estimated to be 0.75 

15

16 

- I ,

to 0.8 (610). Therefore, if covered disposal systems are to be used, 

they must be larger than systems with a free water surface. 

3.2.3 Wastewater Treatment and Disposal in Surface Waters 

Surface waters may be used for the disposal of treated wastewaters if 

permitted by the local regulatory agency. The capacity of surface 

waters to assimilate wastewater pollutants varies with the size and type 

of the body of water. In some cases, because of the potential for human 

contact as well as the concern for maintaining the quality of lakes, 

streams, and wetlands, the use of such waters for disposal are limited. 

Where they can be used, the minimum quality of the wastewater effluent 

to be discharged is specified by the appropriate water quality agency. 

3.3 Site Evaluation Strategy 

The objective of a site investigation is to evaluate the characteristics 

of the area for their potential to treat and dispose of wastewater. A 

good site evaluation is one that provides sufficient information to se- 

lect the most appropriate treatment and disposal system from a broad 

range of feasible options. This requires that the site evaluation begin 

with all options in mind, eliminating infeasible options only as 

collected site data indicate (see Chapter 2). At the completion of the 

investigation, final selection of a system from those feasible options 

is based on costs, aesthetics, and personal preference. 

A site evaluation should be done in a systematic manner to ensure the 

information collected is useful and is sufficient in detail. A sug- 

gested procedure is outlined in Table 3-1 and discussed in the following 

section. This procedure, which can be used to evaluate the feasibility 

of sites for single dwellings or small clusters of dwellings (up to 10 

to 121, is based on the assumption that subsurface soil disposal is the 

most appropriate method of wastewater disposal. Therefore, the suit- 

ability of the soils and other site characteristics for subsurface 

disposal are evaluated first. If found to be unsuitable, then the 

site's suitability for other disposal options is evaluated. 

17

Step 

Client Contact 

Preliminary Evaluation 

Fiel d Testing 

Other Site 

Characteristics 

Organization of Field 

Information 

3.3.1 Client Contact 

TABLE 3-l 

SUGGESTED SITE EVALUATION PROCEDURE 

Data Collected 

Location and description of lot 

Type of use 

Volume and characteristics of 

wastewater 

Available resource information 

(soil maps, geology, etc.) 

Records of onsite systems in 

surrounding area 

Topography and landscape features 

Soil profile characteristics 

Hydraulic conductivity 

If needed, site suitability for 

evaporation or discharge to 

surface waters should be 

evaluated 

Compilation of all data into 

useable form 

Before performing any onsite testing, it is important to gather informa- 

tion about the site that will be useful in evaluating its potential for 

treating and disposing of wastewater. This begins with the party devel- 

oping the lot. The location of the lot and the intended development 

should be established. The volume and character of the generated waste- 

water should be estimated. Any wastewater constituents that may pose 

potential problems in treatment and disposal, such as strong organic 

wastewaters, large quantities of greases, fats or oils, hazardous and 

toxic substances, etc., should be identified. This information helps to 

focus the site evaluation on the important site characteristics. 

18

3.3.2 Preliminary Evaluation 

The next step is to gather any available resource information about the 

site. This includes soils, geology, topography, etc., that may be published 

on maps or in reports. Local records of soil tests, system designs, 

and reported problems with onsite systems installed in the surrounding 

area should also be reviewed. This information may lack accuracy, 

but it can be useful in identifying potential problems or particular 

features to investigate. A plot plan of the lot and the land immediately 

adjacent to it should be drawn to a scale large enough so that 

the information gathered in this and later steps can be displayed on the 

drawing. The proposed layout of all buildings and other manmade features 

should also be sketched in. 

3.3.2.1 Soil Surveys 

Soil surveys are usually found at the local USDA Soil Conservation Ser- 

vice (SCSI office. Also, some areas of the country have been mapped by 

a state agency and these maps may be located at the appropriate state 

office. In counties now being mapped, advance field sheets with inter- 

pretive tables often can be obtained from the SCS. 

Modern soil survey reports are a collection of aerial photographs of the 

mapping area, usually a county, on which the distribution and kind of 

soils are indicated. Interpretations about the potential uses of each 

soil for farming, woodland, recreation, engineeering uses, and other 

nonfarm uses are provided. Detailed descriptions of each soil series 

found in the area are also given. The maps are usually drawn to a scale 

of 4 in. to 1 mile. An example of a portion of a soil map is shown in 

Figure 3-2. 

The map symbols for each mapping unit give the name of the soil series, 

slope, and degree of erosion (10). The soil series name is given a two- 

letter symbol, the first in upper case, the second in lower case. Slope 

is indicated by an upper case letter from A to F. A slopes are flat or 

nearly flat and F slopes are steep. The specific slope range that each 

letter represents differs from survey to survey. The degree of erosion, 

if indicated, is given a number representing an erosion class. The 

classes usually range from 1 to 3, representing slightly eroded to se- 

verely eroded phases. The legend for the map symbols is found immedi- 

ately preceding and following the map sheets in the modern published 

surveys. An example translation of a map symbol from Figure 3-2 is 

given in Figure 3-3. 

19

FIGURE 3-2 

EXAMPLE OF A PORTION OF A SOIL MAP AS PUBLISHED 

IN A DETAILED SOIL SURVEY (ACTUAL SIZE) 

FIGURE 3-3 

TRANSLATION OF TYPICAL SOIL MAPPING UNIT SYMBOL 

Dn C 2 

3 Acres 

Soil Series 1 I Erosion Class 

(Moderately Eroded) 

Slope Class 

(In This Survey 2-6%) 

20 

100'x100' 

oil Absorption 

Area

Interpretations about potential uses of each soil series are listed in 

tables within the text of the report. The soil's suitabiliy for subsur- 

face soil absorption systems and lagoons are specifically indicated. 

Engineering properties are also listed, often including depth to bed- 

rock, seasonal high water table, percolation rate, shrink-swell poten- 

tial, drainage potential, etc. Flooding hazard and other important fac- 

tors are discussed for each mapping unit with the profile descriptions. 

While the soil surveys offer good preliminary information about an area, 

it is not complete nor a substitute for a field study. Because of the 

scale used, the mapping ynits cannot represent areas smaller than 2 to 3 

acres (8,100 to 12,100 m 1. Thus, there may be inclusions of soils with 

significantly different character within mapping units that cannot be 

indicated. For typical building lots, the map loses accuracy. There- 

fore, these maps cannot be substituted for onsite testing in most cases. 

Limitations ratings used by SCS for septic tank-soil absorption systems 

are based on conventional trench or bed designs, and thus do not indi- 

cate the soil's suitability for other designs. Table 3-2 lists the 

criteria used in making the limitation ratings. They are based on a 

soil absorption system with the bottom surface located 2 ft (0.6 m) 

below the soil surface. In many cases, the limitations can be overcome 

through proper design. Therefore, the interpretations should be used 

only as a guide. 

The information provided by the soil survey should be transferred to the 

site drawing along with other important information. An example for a 

parcel is shown in Figure 3-4. Information for each of the soil sites 

shown on Figure 3-4 is presented in Table 3-3. 

3.3.2.2 U.S. Geological Survey Quadrangles 

Quadrangles published by the U.S. Geological Survey may be useful in 

estimating slope, topography, local depressions or wet areas, rock out- 

crops, and regional drainage patterns and water table elevations. These 

maps are usually drawn to a scale of 1:24,000 (7.5 minute series) or 

1:62,500 (15 minute series). However, because of their scale, they are 

of limited value for evaluating small parcels. 

21

Property 

USDA Texture 

Flooding 

Depth to Bedrock, 

in. 

Depth to Cemented 

Pan, in. 

Depth to High 

Water Table, ft 

below ground 

Permeability, 

in./hr 

24-60 in. layer 

layers (24 in. 

Slope, percent 

Fraction >3 in., 

percent by wt 

TABLE 3-2 

SOIL LIMITATIONS RATINGS USED BY SCS 

FOR SEPTIC TANK/SOIL ABSORPTION FIELDS 

[Modified after (1011 

Limits Restrictive 

Sl' ght Moderate Severe Feature 

---- 

None, 

Protected 

>72 

>72 

>6 

2.0-6.0 

--- 

O-8 

~25 

3.3.2.3 Local Records 

---- Ice 

Rare Common 

40-72 50 

Permafrost 

Floods 

Depth to Rock 

Depth to 

Cemented Pan 

Ponding, 

Wetness 

Slow Pert. Rate 

Poor Filter 

Slope 

Large Stones 

Soil test reports and records of reported failure of onsite systems from 

the surrounding area may be a source of valuable information. The soil 

test reports can provide an indication of soil types and variability. 

Performance of systems may be determined from the reported failures. 

These records are usually available from the local regulatory agency, 

22

FIGURE 3-4 

PLOT PLAN SHOWING SOIL SERIES BOUNDARIES 

FROM SOIL SURVEY REPORT 

Drainage 

Way 

0 

Well, 

Adjacent Lot 

23 

Soil 

Boundary 7 

‘.‘.‘:::.: .;::::, .,.,.,._.,.;_.,...... .;; ::,., ‘.‘::;.~ 

.,._.,.,.,.,.,....., 

‘,.,.,‘,.,.~‘,‘,.~‘,.,~,~, 

.:;_._.,: _, 

~.~.~.~.‘.‘.‘.‘.‘.‘.~.~.‘. .;,.,., _...,:. :,:,:.:.: .;,.,., ,,.,_, 

~.~.'_'_'.~.'.'.~.'.'.'.'.'.~ 

. . ., .,._.,., . ..:_ . .,.,.,_,.,.,.,._ _ ._.;, Property 

::::::::::::.:.:.:,:.:.:.:.:.:::: 

.::. . .,.; 

.; ,.:. ~,~,~_~,~,~.~,'.','.~. .:,I 

. .: :,._._., ,..._ ., .,.. I--- Line

TABLE 3-3 

SOIL SURVEY REPORT INFORMATION 

FOR PARCEL IN FIGURE 3-4 

Soil 

Absorption Depth to 

Map 

-- Symbol 

Soil 

Series 

T 

Limitation 

Rating 

Flood 

Hazard 

- 

High Water 

Table 

ft 

Depth to 

Bedrock 

ft 

Permeability 

Depth Perm. 

in. in./hr 

DnC2 Dodge 2-6 Moderate No >5 5-10 O-40 0.63-2.0 

40-60 2.0-6.3 

TrB Troxel 2-6 Severe Yes 3-5 >lO O-60 0.63-20 

PnB Plano 2-6 Moderate No 3-5 >lO o-41 0.63-2.0 

41-60 2.0-6.3 

3.3.3 Field Testing 

Field testing begins with a visual survey of the parcel to locate poten- 

tial sites for subsurface soil absorption. Soil borings are made in the 

potential sites to observe the soil characteristics. Percolation tests 

may be conducted in those soils that appear to be well suited. If no 

potential sites can be found from either the visual survey, soil bor- 

ings, or percolation tests, then other means of disposal should be 

investigated. 

3.3.3.1 Visual Survey 

A visual survey is made to locate the areas on the lot with the greatest 

potential for subsurface soil absorption. The location of any depres- 

sions gullies, steep slopes, rocks or rock outcrops, or other obvious 

land and surface features are noted and marked on the plot plan. Vege- 

tation types are also noted that may indicate wetness or shallow soils. 

Locations and distances from a permanent benchmark to lot lines, wells, 

surface waters, buildings, and other features or structures are also 

marked on the plot plan (see Figure 3-5). If a suitable area cannot be 

24

FIGURE 3-5 

PLOT PLAN SHOWING SURFACE FEATURES 

400 Ft. * 

4 v 

.!30 Ft. 25 Ft. 

0 

'Well' T 

25

found for a subsurface soil absorption system based on this information 

other disposal options must be considered (see Chapter 2). The remain- 

der of the field testing can be altered accordingly. 

3.3.3.2 Landscape Position 

The landscape position and landform for each suitable area should be 

noted. Figure 3-6 can be used as a guide for identifying landscape 

positions. This information is useful in estimating surface and subsur- 

face drainage patterns. For example, hilltops and sideslopes can be 

expected to have good surface and subsurface drainage, while depressions 

and footslopes are more likely to be poorly drained. 

3.3.3.3 Slope 

The type and degree of slope of the area should be determined. The type 

of slope indicates what surface drainage problems may be expected, For 

example, concave slopes cause surface runoff to converge, while convex 

slopes disperse the runoff (see Figure 3-6). 

Some treatment and disposal systems are limited by slopes. Therefore, 

slope measurement is important. Land slopes can be expressed in several 

ways (see Figure 3-7): 

1. PERCENT OF GRADE - The feet of vertical rise or fall in 100 ft 

horizontal distance. 

2. SLOPE - The ratio of vertical rise or fall to horizontal 

distance. 

3. ANGLE - The degrees and minutes from horizontal. 

4. TOPOGRAPHIC ARC - The feet of vertical rise or fall in 66 ft 

(20 m) horizontal distance. 

Land slopes are usually determined by measuring the slope of a line 

parallel to the ground with an Abney Level either at eye height or at 

some other fixed height above the ground. If an ordinary hand level is 

used, then slopes are determined by horizontal line of sight which give 

changes in elevation for specific horizontal distances. A hand level is 

limited in use because it is best suited for slope determinations up 

grade only, but has the advantage that only one person is needed for 

mapping slopes. Three methods of slope determinations are discussed 

below. 

26

FIGURE 3-6 

LANDSCAPE POSITIONS 

Depression 

/ /- Ridge Line 

Slope 

FIGURE 3-7 

METHODS OF EXPRESSING LAND SLOPES (10) 

Percent of Grade - 20 

Slope-l :5 

Angle - 11 O 19’ 

Topographic Arc - 13.2 

Concave 

Slope 

Horizontal 66' 100' 

27 

Slope

Instrument Supported - Abney Level: For accurate slope determinations, 

notch two sticks or cut forked sticks so they will hold the level 5 ft 

(1.5 m) above the ground. Rest the level in the notch or fork and sight 

to the notch or fork of the other stick held by another person at a 

point on the slope. The land slope is read directly in percent on the 

Abney Level. 

Abney Level: On level ground, sight the person working with you to 

determine the point of intersection of your line of sight on him when 

the instrument is in position for use as a hand level (zero level posi- 

tion). When he is on the slope, sight the same point on the person 

assisting you and read the slope directly. 

Hand Level: Height of eye must be determined. Then sight the point of 

interception with the ground surface and determine, by tape measurement 

or pacing, the ground surface distance between the sighting point and 

the point of intercept. To calculate land slope in percent, divide your 

height of eye by the ground surface distance and multiply by 100. 

Using one of the above procedures or other surveying methods, slopes at 

selected sites can be determined so that topography can be mapped. The 

number of sites needed will depend on the complexity of slopes. Slope 

determinations should be made at each apparent change in slope at known 

locations so steep slope areas can be accurately drawn. Experience will 

be required for proficiency and accuracy in mapping. Steep slope areas 

in natural topography have irregular form and curved boundaries. 

Uniform boundaries having straight lines and angular corners indicate 

man-altered conditions. For large areas it may be necessary to draw 

contour lines so that slopes at different points in the plot can be 

determined. 

3.3.3.4 Soil Borings 

Observation and evaluation of soil characteristics can best be deter- 

mined from a pit dug by a backhoe or other excavating equipment. How- 

ever, an experienced soil tester can do a satisfactory job by using a 

hand auger or probe. Both methods are suggested. Hand tools can be 

used to determi.ne soil variability over the area and pits used to de- 

scribe the various soil types found. 

Soil pits should be prepared at the perimeter of the expected soil 

absorption area. Pits prepared within the absorption area often settle. 

after the system has been installed and may disrupt the distribution 

network. If hand augers are used, the holes may be made within the 

28

absorption 'area. Sufficient borings or pits should be made to ade- 

quately describe the soils in the area, and should be deep enough to 

assure that a sufficient depth of unsaturated soil exists below the 

proposed bottom elevation of the absorption area. Variable soil 

conditions may require many pits. 

Since in some cases subtle differences in color need to be recognized, 

it is often advantageous to prepare the soil pit so the sun will be 

shining on the face during the observation period. Natural light will 

give true color interpretations. Artificial lighting should not be 

used. 

3.3.3.5 Soil Texture 

Texture is one of the most important physical properties of soil because 

of its close relationship to pore size, pore size distribution, and pore 

continuity. It refers to the relative proportion of the various sizes 

of solid particles in the soil that are smaller than 2 mm in diameter. 

The soil texture is determined in the field by rubbing a moist sample 

between the thumb and forefinger. A water bottle is useful for moistur- 

izing the sample. The grittiness, "silkiness," or stickiness can be 

interpreted as being caused by the soil separates of sand, silt, and 

clay. It is extremely helpful to work with some known samples to gain 

experience with field texturing. 

While laboratory analysis of soil texture is done routinely by many lab- 

oratories, field texturing can give as good information as laboratory 

data and therefore expenditures of time and money for laboratory analy- 

ses are not necessary. To determine the soil texture, moisten a sample 

of soil about one-half to one inch in diameter. There should be just 

enough moisture so that the consistency is like putty. Too much mois- 

ture results in a sticky material, which is hard to work. Press and 

squeeze the sample between the thumb and forefinger. Gradually press 

the thumb forward to try to form a ribbon from the soil (see Figure 

3-8). By using this procedure, the texture of the soil can be easily 

described. 

Table 3-4 and Figures 3-9 and 3-10 describe the feeling and appearance 

of the various soil textures for a general soil classification. 

29

FIGURE 3-8 

PREPARATION OF SOIL SAMPLE FOR FIELD 

DETERMINATION OF SOIL TEXTURE 

(A) Moistening Sample 

(B) Forming Cast 

(C) Ribboning

Soil 

Class 

Sand 

Sandy Loam 

Loam 

Silt Loam 

Clay Loam 

Clay 

TABLE 3-4 

TEXTURAL PROPERTIES OF MINERAL SOILS 

Feeling and Appearance 

Drv Soil Moist Sol1 

Loose, single grains which 

feel gritty. Squeezed in 

the hand, the soil mass 

falls apart when the 

pressure is released. 

Aggregates easily crushed; 

very faint velvety feeling 

initially but with continued 

rubbing the gritty feeling 

of sand soon dominates. 

Aggregates are crushed under 

moderate pressure; clods can 

be quite firm. When pulver- 

ized, loam has velvety feel 

that becomes gritty with 

continued rubbing. Casts 

bear careful handling. 

Aggregates are firm but may 

be crushed under moderate 

pressure. Clods are firm to 

hard. Smooth, flour-like 

feel dominates when soil is 

pulverized. 

Very firm aggregates and 

hard clods that strongly 

resist crushing by hand. 

When pulverized, the soil 

takes on a somewhat gritty 

feeling due to the harshness 

of the very small aggregates 

which persist. 

Aggregates are hard; clods 

are extremely hard and 

strongly resist crushing by 

hand. When pulverized, it 

has a grit-like texture due 

to the harshness of numerous 

very small aggregates which 

persist. 

31 

Squeezed in the hand, it 

forms a cast which crumbles 

when touched. Does not form 

a ribbon between thumb and 

forefinger. 

Forms a cast which bears 

careful handling without 

breaking. Does not form a 

ribbon between thumb and 

forefinger. 

Cast can be handled quite 

freely without breaking. 

Very slight tendency to 

ribbon between thumb and 

forefinger. Rubbed surface 

is rough. 

Cast can be freely handled 

without breaking. Slight 

tendency to ribbon between 

thumb and forefinger. Rubbed 

surface has a broken or 

rippled appearance. 

Cast can bear much handling 

without breaking. Pinched 

between the thumb and 

forefinger, it forms a ribbon 

whose surface tends to feel 

slightly gritty when dampened 

and rubbed. Soil is plastic, 

sticky and puddles easily. 

Casts can bear considerable 

handling without breaking. 

Forms a flexible ribbon 

between thumb and forefinger 

and retains its plasticity 

when elongated. Rubbed 

surface has a very smooth, 

satin feeling. Sticky when 

wet and easily puddled.

Sandy 

Loam + _. ,i 

. 

L 

Silt 

Loam 

Clay 

FIGURE 3-9 

SOIL TEXTURE DETERMINATION BY HAND: PHYSICAL 

APPEARANCE OF VARIOUS SOIL TEXTURES 

Dry 

Moist 

Weak Aggregates No Ribbon; Non-Plastic Cast 

Firm Aggregates 

Hard Aggregates 

32 

Very Slight Ribboning 

Tendency; Moderately 

Plastic Cast 

Ribbons Easily; Plastic Cast

FIGURE 3-10 

COMPARISON OF RIBBONS AND CASTS OF SANDY LOAM 

AND CLAY (RIBBONS ABOVE, CASTS BELOW) 

If the soil sample ribbons (loam, clay loam, or clay), it may be desir- 

able to determine if sand or silt predominate. If there is a gritty 

feel and a lack of smooth talc-like feel, then sand very likely predomi- 

nates. If there is a lack of a gritty feel but a smooth talc-like feel, 

then silt predominates. If there is not a predominance of either the 

smooth or gritty feel, then the sample should not be called anything 

other than a clay, clay loam, or loam. If a sample feels quite smooth 

with little or no grit in it, and will not form a ribbon, the sample 

would be called silt loam. 

Beginning at the top or bottom of the pit sidewall, obvious changes in 

texture with depth are noted. Boundaries that can be seen are marked. 

The texture of each layer or horizon is determined and the demarcations 

of boundaries changed as appropriate. When the textures have been 

determined for each layer, the depth, thickness, and texture of each 

layer is recorded (see Figure 3-11). 

3.3.3.6 Soil Structure 

Soil structure has a significant influence on the soil's acceptance and 

transmission of water. Soil structure refers to the aggregation of soil 

particles into clusters of particles, called peds, that are separated by 

surfaces of weakness. These surfaces of weakness open planar pores 

between the peds that are often seen as cracks in the soil. These pla- 

nar pores can greatly modify the influence of soil texture on water 

movement. Well-structured soils with large voids between peds will 

transmit water more rapidly than structureless soils of the same tex- 

ture, particularly if the soil has become dry before the water is 

added. Fine-textured, massive soils (soils' with little structure) have 

very slow percolation rates. 

33

Depth 

(Ft.) 

0 

2 

4 

6 

8 

10 

12 

14 

Texture 

Silt 

Loam 

Silty 

Clay Loan 

Zlay Loam 


Loam 

I 

FIGURE 3-11 

EXAMPLE PROCEDURE FOR COLLECTING 

SOIL PIT OBSERVATION INFORMATION 

Structure 

Granular 

Platv 

Blocky 

Platy 

Massive 

34 

Color 

Soil Saturation 

Brown None

If a detailed analysis of the soil structure is necessary, the sidewall 

of the soil pit should be carefully examined, using a pick or similar 

device to expose the natural cleavages and planes of weakness. Cracks 

in the face of the soil profile are indications of breaks between soil 

peds. The shapes created by the cracks should be compared to the shapes 

shown in Figure 3-12. If cracks are not visible, a sample of soil 

should be carefully picked out and, by hand, carefully separated into 

the structural units until any further breakdown can only be achieved by 

fracturing. 

Since the structure can significantly alter the hydraulic characteris- 

tics of soils, more detailed descriptions of soil structure are some- 

times desirable. Size and grade of durability of the structural units 

provide useful information to estimate hydraulic conductivities. De- 

scriptions of types and classes of soil structure used by SCS are given 

in Appendix A. Grade descriptions are given in Table 3-5. The type, 

size, and grade of each horizon or zone is recorded in Figure 3-11. 

3.3.3.7 Soil Color 

The color and color patterns in soil are good indicators of the drainage 

characteristics of the soil. Soil properties, location in the la,nd- 

scape, and climate all influence water movement in the soil. These 

factors cause some soils to be saturated or seasonally saturated, 

affecting their ability to absorb and treat wastewater. Interpretation 

of soil color aids in identifying these conditions. 

Color may be described by estimating the true color for each horizon or 

by comparing the soil with the colors in a soil color book. In either 

case, it is particularly important to note the colors or color patterns. 

Pick up some soil and, without crushing, observe the color. It is 

important to have good sunlight and know the moisture status of the 

sample. If ped faces are dry, some water applied from a mist bottle 

will allow observation of moist colors. 

Though it is often adequate to speak of soil colors in general terms, 

there is a standard method of describing colors using Munsell color 

notation. This notation is used in soil survey reports and soil de- 

scription. Hue is the dominant spectral color and refers to the light- 

ness or darkness of the color between black and white. Chroma is the 

relative purity of strength of the color, and ranges from gray to a 

bright color of that hue. Numbers are given to each of the variables 

and a verbal description is also given. For example, 1OYR 3/2 corre- 

sponds to a color hue of 1OYR value of 3 and chroma 2. This is a very 

dark grayish brown. 

35

Grade 

Structureless 

Weak 

Moderate 

Strong 

Prismatic 

-%iLLs--> 

-=I!= 

If a soil color book is used to determine soil colors, hold the soil and 

book so the. sun shines over your shoulder. Match the soil color with 

the color chip in the book. Record the hue, chroma and value, and the 

color name. 

Mottling in soils is described by the color of the soil matrix and the 

color or colors, size, and number of the mottles. Each color may be 

given a Munsell designation and name. However, it is often sufficient 

to say the soil is mottled. A classification of mottles used by the 

USDA is shown in Table 3-6. Some examples of soil mottling are shown on 

the inside back cover of this manual. 

Character Class 

Abundance Few 

Common 

Many 

TABLE 3-6 

DESCRIPTION OF SOIL MOTTLES (10) 

Limit 

~2% of exposed face 

Z-20% of exposed face 

>20% of exposed face 

Size Fine 15mm longest dimension 

Contrast Faint 

Distinct 

Prominent 

3.3.3.8 Seasonally Saturated Soils 

Recognized only by close observation 

Readily seen but not striking 

Obvious and striking 

Seasonally saturated soils can usually be detected by soil borings made 

during the wet season or by the presence of mottled soils (see 3.3.3.7). 

For large cluster systems or for developments where each dwelling is 

served by an onsite system, the use of observation wells may be justi- 

fied. They are constructed as shown in Figure 3-13. The well should be 

placed in, but not extended through, the horizon that is to be moni- 

tored. More than one well in each horizon that may become seasonally 

saturated is desirable. The wells are monitored over a normal wet sea- 

son by observing the presence and duration of water in the well. If 

water remains in the well for several days, the water level elevation is 

measured and assumed to be the elevation of the seasonally saturated 

soil horizon. 

37

Excavated Soil Material 

(Tamped in when placing 

l"-4" Diameter 

Soil Horizon 

FIGURE 3-13 

TYPICAL OBSERVATION WELL FOR 

DETERMINING SOIL SATURATION 

3.3.3.9 Other Selected Soil Characteristics 

,I 

Puddled Clav 

-or Equal Parts-of 

SoilandCement 

Mixture 

1h"-3/4" Gravel 

Soil bulk density is related to porosity and the movement of water. 

High bulk density is an indication of low porosity and restricted flow 

of water. Relative bulk densities of different soil horizons can be 

detected in the field by pushing a knife or other instrument into each 

horizon. If one horizon offers, considerably more resistance to penetra- 

tion than the others, its bulk density is probably higher. However, in 

some cases, cementing agents between soil grains or .peds may be the 

cause of resistance to penetration. 

Swelling clays, particularly montmorillonite clays, can seal off soil 

pores when wet. They can be detected'during field texturing of the soil 

by their tendency to be more sticky and plastic when wet. 

38

3.3.3.10 Hydraulic Conductivity 

Several methods of measuring the hydraulic conductivity of soils have 

been developed (l)(ll). The most commonly used test is the percolation 

test. When run properly, the test can give an approximate measure of 

the soil's saturated hydraulic conductivity. However, the percolation 

of wastewater through soil below soil disposal systems usually occurs 

through unsaturated soils. Therefore, empirical factors must be used to 

estimate unsaturated conductivities. The unsaturated hydraulic conduc- 

tivities can vary dramatically from the saturated hydraulic conductivity 

with changes in soil characteristics and moisture content (see Appendix 

A). 

The percolation test is often criticized because of its variability and 

failure to measure the hydraulic conductivity accurately. Percolation 

tests conducted in the same soils can vary by 90% or more (1)(11)(12) 

(13) (14) 0 Reasons for the large variability are attributed to the pro- 

cedure used, the soil moisture conditions at the time of the test, and 

the individual performing the test. Despite these shortcomings, the 

percolation test can be useful if used together with the soil borings 

data. The test can be used to rank the relative hydraulic conductivity 

of the soil. Estimated percolation rates for various soil textures are 

given in Table 3-7. 

Soil Texture 

TABLE 3-7 

ESTIMATED HYDRAULIC CHARACTERISTICS OF SOIL (15) 

Sand >6.0 (10 

Sandy loams 

Porous silt loams 

Silty clay loams 

Clays, compact 

Silt loams 

Silty clay loams 

Percolation 

ml n/in. 

0.2-6.0 10-45 

39 

x0.2 >45

If test results agree with this table, the test and boring data are 

probably correct and can be used in design. If not, either the test was 

run improperly or soil structure or clay mineralogy have a significant 

effect on the hydraulic conductivity. For example, if the texture of a 

soil isadetermined to be a clay loam, the estimated percolation rate is 

slower than 45 min/in. (18 min/cm). If the measured percolation rate is 

15 min/in. (6 min/cm), however, either the texture is incorrect or the 

soil has strong structure with large cracks between peds. The tester 

should be cautious in such soils because the unsaturated hydraulic 

conductivity may be many times less. Expandable clays may be present 

that could close many of the pores. 

Several percolation test procedures are used (11) (16). The most common 

procedure is the falling head test (11). Though less reproducible than 

other procedures, it is simple to perform in the field (11) (12). The 

falling head procedure is outlined in Table 3-8. A diagram of ,a 

"percometer" designed to simplify the testing is illustrated in Figure 

3-14. For a discussion of other methods see the National Environmental 

Health Association's "On-Site Wastewater Management" (16). 

Data collected from the percolation test can be tabulated using a form 

similar to the one illustrated in Figure 3-15. 

3.3.4 Other Site Characteristics 

If subsurface disposal does not appear to be a viable option or 

cost-effective, other methods of disposal are evaluated (see Chapter 2). 

Evaporation and discharge to surface waters are other options to 

investigate. Each requires further site evaluation. 

3.3.4.1 Site Evaluation of Evaporation Potential 

Evaporation and evapotranspiration can be used as the sole means of dis- 

posal or as a supplement to soil absorption. To be effective, evapora- 

tion should exceed precipitation in the area. The difference between 

evaporation and precipitation rates provides estimates of quantities of 

water that can be evaporated from a free water surface. 

Weather data can be obtained from local weather stations and the Na- 

tional Oceanic and Atmosphere Administration (NOAA). Rainfall and snow- 

fall measurements are available from NOAA for thousands of weather sta- 

tions throughout the country. Many local agencies also maintain rec- 

ords. A critical wet year is typically used for design based on at 

least 10 years of records (18). 

40

1. Number and Location of Tests 

TABLE 3-8 

FALLING HEAD PERCOLATION TEST PROCEDURE 

Commonly a minimum of three percolation tests are performed within the area proposed 

for an absorption system. They are spaced uniformly throughout the area. If soil 

conditions are highly variable, more tests may be reauired. 

2. Preparation of Test Hole 

The diameter of each test hole is 6 in., dug or bored to the proposed depths at the 

absorption systems or to the most limiting soil horizon. To expose a natural soil 

surface, the sides of the hole are scratched with a sharp pointed instrument and the 

loose material is removed from the bottom of the test hole. Two inches of l/2 to 3/4 

in. gravel are placed in the hole to protect the bottom from scouring action when the 

water is added. 

3. Soaking Period 

The hole is carefully filled with at least 12 in. of clear water. This depth of 

water should be maintained for at least 4 hr and preferably overnight if clay soils 

are present. A funnel with an attached hose or similar device may be used to prevent 

water from washing down the sides of the hole. Automatic siphons or float valves may 

be employed to automatically maintain the water level during the soaking period. It 

is extremely important that the soil be allowed to soak for a sufficiently long 

period of time to allow the soil to swell if accurate results are to be obtained. 

In sandy soils with little or no clay, soaking is not necessary. If, after fillinq 

the hole twice with 12 in. of water, the water seeps completely away in less than ten 

minutes, the test can proceed immediately. 

4. Measurement of the Percolation Rate 

Except for sandy soils, percolation rate measurements are made 15 hr but no more than 

30 hr after the soaking period began. Any soil that sloughed into the hole during 

the soaking period is removed and the water level is adjusted to 6 in. above the 

gravel (or 8 in. above the bottom of the hole). At no time during the test is the 

water level allowed to rise more than 6 in. above the gravel. 

Immediately after adjustment, the water level is measured from a fixed reference 

point to the nearest l/16 in. at 30 min intervals. The test is-continued until two 

successive water level drops do not vary by more than l/16 in. At least three 

measurements are mde. 

After each measurement, the water level is readjusted to the 6 in. level. The last 

water level drop is used to calculate the percolation rate. 

In sandy soils or soils in which the first 6 in. of water added after the soakinq 

period seeps away in less than 30 min, water level measurements are made at 10 min 

intervals for a 1 hr period. The last water level drop is used to calculate the 

percolation rate. 

5. Calculation of the Percolation Rate 

The percolation rate is calculated for each test hole by dividinq the time interval 

used between measurements by the magnitude of the last water level drop. This 

calculation results in a percolation rate in terms of min/in. To determine the 

percolation rate for the area, the rates obtained from each hole are averaged. (If 

tests in the area vary by more than 20 min/in., variations in soil type are 

indicated. Under these circumstances, percolation rates should not be averaged.1 

Example: If the last measured drop in water level after 30 min is 5/8 in., the 

percolation rate = (30 mini/(5/8 in.1 = 48 min/in. 

41

Percolation test 

FIGURE 3-15 

PERCOLATION TEST DATA FORM (17) 

Location Lb- /as’, /f tqh t&M /f&x fs S&/rw/~,u~ 

Test hole number 3 

Depth to bottom of hole 2 Y inches. Diameter of hole 6 inches. 

Depth, inches Soil texture 

o-L/ 4ik ?%p SO// 

4- / 2. L m ,i 

/;z -2’ b /-4 5.c / 

Percolation test by CC 2 7-e 5-f-e r 

Date of test b/3 f/80 

Percolation rate = ‘7L$ minutes per inch. 

43

Establishing evaporation data at a specific location can be a more 

difficult problem. Measurements of Class A pan evaporation rates are 

reported for all of the states by NOAA in the publication, 

"Climatological Data," U.S. Department of Commerce, available in 

depository libraries for government documents at major universities in 

each state. Pan evaporation measurements are made at a few (5 to 30) 

weather stations in each state. Data for the winter months are often 

omitted because this method cannot be used under freezing weather 

conditions. The critical period of the year for design of systems for 

permanent homes is in the winter. Obtaining representative winter 

evaporation data is probably the most difficult part of design analysis. 

Application of evaporation systems is most favorable in the warm, dry 

climates of the southwestern United States. For these areas, pan 

evaporation data are available for the complete year. The analysis of 

evaporative potential for cooler, semi-arid regions, such as eastern 

Washington and Oregon, Utah, Colorado, and similar areas, requires that 

winter data be established by means other than pan evaporation 

measurements, since these data are generally not available. 

One method for establishing representative winter evaporation data i’s to 

take measurements on buried lysimeters. Another method is to use empir- 

ical formulations such as the Penman formula (18). The Penman formula 

has been shown to give results comparable to measured winter values 

(5). 

3.3.4.2 Site Evaluation for Surface Water Discharge 

For surface water disposal to be a viable option, access to a suitable 

surface body of water must be available. Onsite investigations must 

locate the body of water, identify it, and determine the means by which 

access can be gained. Since discharges to surface waters are usually 

regulated, the local water quality agency must be contacted to learn if 

discharge of wastewater into that body of water is permitted and, if so, 

what effluent standards must be met. 

3.3.5 Organizing the Site Information 

As the site information is collected, it is organized so that it can be 

easily used to check site suitability for any of the various systems 

discussed in this manual. One such method of organization is shown in 

Figure 3-16. In this example, two soil observations have been made. 

The number of soil observations varies. It is important that all perti- 

nent site information be presented in a clear fashion to provide suffi- 

cient information to the designer of the system without making addi- 

tional site visits. 

44

mm..--- 

- --- 

FIGURE 3-16 

COMPILATION OF SOILS AND SITE INFORMATION 

(INFORMATION INCLUDES TOPOGRAPHIC, SOIL SURVEY, 

ONSITE SLOPE AND SOIL PIT OBSERVATIONS) 

Name ),-‘ ~6, 4 :,g A., ,:/, I/f-- 

Site evaluator CJ.kfefl 

Address J+TmS, H.4 a%fs &dfs ., Address L.dke i.‘,/ y , ,Y. 5 H. 

/ 

Waste water quantity A(.; --;.. 

gpd 

h Soil Pit 

0 Percolation 

Set Back 

Contour 

Tests (If Determined) 

Soil Boundary 

Drainage Way 

45

Depth 

Ft.) 

0 

2 

4 

6 

8 

10 

12 

14 

Name : ,qr s/d~r? f- 

Soi. Pit No. 1 

ITexture 

Silt 

Loam 

Silty 

Clay 

Loam 

Clay Loam 


Loam 

FIGURE 3-16 (continued) 

Structure 

Granular 

Platy 

Blocky 

Platy 

Massive 

- 

Color 

Soil Map Unit - ,&&2 

Slope -6% 

Landscape Position - Side Slop& 

Landscape Type - Plane to Concave 

46 

Soil Saturation 

Brown None

FIGURE 3-16 (continued) 

0 Texture Structure Color Soil Saturation 

2 

4 

6 

8 

10 

12 

14 

Name: e&5;& df- 

Soil Pit No..L 

Silt 

Loam 

Silty 

Clay 

Loam 

Silt Loam 

Blocky 

Granular 

Brown 

Black 

Blocky Brown 

Massive 

Soil Map Unit -m 

Slope - 4% 

LandscapePosition - Footslope 

Landscape Type - Concave 

47 

I 

-

3.4 References 

1. Small Scale Waste Management Project, University of Wisconsin, 

Madison. Management of Small Waste Flows. EPA 600/2-78-173, NTIS 

Report No. PB 286 560, September 1978. 804 pp. 

2. Tyler, E. J., R. Laak, E. McCoy, and S. S. Sandhu. The Soil as a 

Treatment System. In: Proceedings of the Second National Home 

Sewage Treatment SFposium, Chicago, Illinois, December 1977. 

American Society of Agricultural Engineers, St. Joseph, Michigan, 

1978. pp. 22-37. 

3. Hillel, D. I. Soil and Water: Physical Principles and Processes. 

Academic Press, New York, 1971. 302 pp. 

4. Flach, K. W. Land Resources. In: Recyclying Municipal Sludges 

and Effluents on Land. Champaign, University of Illinois, July 

1973. 

5. Bennett, E. R., and K, D. Linstedt. Sewage Disposal by Evaporation- 

Transpiration. EPA 600/2-78-163, NTIS Report No. PB 288 588, 

September 1978. 196 pp. 

6. Pickett, E. M. Evapotranspiration and Individual Lagoons. In: 

Proceedings of Northwest Onsite Wastewater Disposal Short Courz, 

University of Washington, Seattle, December 1976. pp. 108-118. 

7. Pruitt, W. 0. Empirical Method for Estimating Evapotranspiration 

Using Primarily Evaporation Pans. In: Evapotranspiration and Its 

Role in Water Resources Management;Tonference Proceedings, Ameri- 

can Society of Agricultural Engineers, St. Joseph, Michigan, 1966. 

pp. 57-61. 

8. Beck, A. F. Evapotranspiration Pond Design. Environ. Eng. Div., 

Am. Sot. Civil Eng., 105 411-415, 1979. 

9. Bernhart, A. P. Treatment and Disposal of Wastewater From Homes by 

Soil Infiltration and Evapotranspiration. 2nd ed. University of 

Toronto Press, Toronto, Canada, 1973. 

10. Soil Conservation Service. Soil Survey Manual. USDA Handbook 18, 

U.S. Government Printing Office, Washington, D.C., 1951. 503 pp. 

11. Studies on Household Sewage Disposal Systems. Environmental Health 

Center, Cincinnati, Ohio, 1949-3 pts. 

12. Bouma, J. Evaluation of the Field Percolation Test and an Alter- 

native Procedure to Test Soil Potential for Disposal of Septic Tank 

Effluent. Soil Sci. Sot. Amer. Proc. 35:871-875, 1971. 

48

13. Winneberger, J. T. Correlation of Three Techniques for Determining 

Soil Permeability. Environ. Health, 37:108-118, 1974. 

14. Healy, K. A., and R. Laak. Factors Affecting the Percolation Test. 

J. Water Pollut. Control Fed., 45:1508-1516, 1973. 

15. Bouma, J. Unsaturated Flow During Soil Treatment of Septic Tank 

Effluent. J. Environ. Eng., Am. Sot. Civil Eng., 101:967-983, 

1975. 

16. Onsite Wastewater Management. National Environmental Health Asso- 

ciation, Denver, Colorado, 1979. 

17. Machmeier, R. E. How to Run a Percolation Test. Extension Folder 

261, University of Minnesota, St. Paul, 1977. 

18. Penman, H. L. Estimating Evaporation. Trans. Amer. Geophys. 

Union, 37:43-46, 1956. 

49


CHAPTER 4 

WASTEWATER CHARACTERISTICS 

The effective management of any wastewater flow requires a reasonably 

accurate knowledge of its characteristics. This is particularly true 

for wastewater flows from rural residential dwellings, commercial estab- 

lishments and other facilities where individual water-using activities 

create an intermittent flow of wastewater that can vary widely in volume 

and degree of pollution. Detailed characterization data regarding these 

flows are necessary not only to facilitate the effective design of 

wastewater treatment and disposal systems, but also to enable the de- 

velopment and application of water conservation and waste load reduction 

strategies. 

For existing developments, characterization of the actual wastewaters to 

be encountered may often times be accomplished. However, for many exis- 

ting developments, and for almost any new development, wastewater char- 

acteristics must be predicted. The purpose of this chapter is to 

provide a basis for characterizing the wastewater from rural develop- 

ments. A detailed discussion of the characteristics of residential 

wastewaters is presented first, followed by a limited discussion of the 

characteristics of the wastewaters generated by nonresidential estab- 

lishments, including those of a commercial, institutional and recrea- 

tional nature. Finally, a general procedure for predicting wastewater 

characteristics for a given residential dwelling or nonresidential 

establishment is given. 

4.2 Residential Wastewater Characteristics 

Residential dwellings exist in a variety of forms, including single- and 

multi-family households, condominium homes, apartment houses and 

cottages or resort residences. In all cases, occupancy can occur on a 

seasonal or year-round basis. The wastewater discharged from these 

dwellings is comprised of a number of individual wastewaters, generated 

through water-using activities employing a variety of plumbing fixtures 

and appliances. The characteristics of the wastewater can be influenced 

by several factors. Primary influences are the characteristics of the 

plumbing fixtures and appliances present as well as their frequency of 

use. Additionally, the characteristics of the residing family in terms 

of number of family members, age levels, and mobility are important as 

50

is the overall socioeconomic status of the family. The characteristics 

of the dwelling itself, including seasonal or yearly occupancy, 

geographic location, and method of water supply and wastewater disposal, 

appear as additional, but lesser, influences. 

4.2.1 Wastewater Flow 

4.2.1.1 Average Daily Flow 

The average daily wastewater flow from a typical residential dwelling is 

approximately 45 gal/capita/day (gpcd) (170 liters/capita/day [lpcd]) 

(Table 4-l). While the average daily flow experienced at one residence 

compared to that of another can vary considerably, it is typically no 

greater than 60 gpcd (227 lpcd) and seldom exceeds 75 gpcd (284 lpcd) 

(Figure 4-l). 

4.2.1.2 Individual Activity Flows 

The individual wastewater generating activities within a residence are 

the building blocks that serve to produce the total residential waste- 

water discharge. The average characteristics of several major residen- 

tial water-using activities are presented in Table 4-2. A water-using 

activity that falls under the category of miscellaneous in this table, 

but deserves additional comment, is water-softener backwash/regeneration 

flows. Water softener regeneration typically occurs once or twice a 

week, discharging about 30-88 gal (114 to 333 1) per regeneration cycle 

(11). On a daily per capita basis, water softener flows have been shown 

to average about 5 gpcd (19 lpcd), ranging from 2.3 to 15.7 gpcd (8.7 to 

59.4 lpcd) (7). 

4.2.1.3 Wastewater Flow Variations 

The intermittent occurrence of individual wastewater-generating activi- 

ties creates large variations in the wastewater flow rate from a resi- 

dence. 

a. Minimum and Maximum Daily Flows 

The daily wastewater flow from a specific residential dwelling is typ- 

ically within 10% and 300% of the average daily flow at that dwelling, 

with the vast majority within 50 and 150% of the average day. At the 

51

TABLE 4-l 

SUMMARY OF AVERAGE DAILY RESIDENTIAL WASTEWATER FLOWS 

Wastewater Flow 

St dy Range of Individual 

Aveyage Residence Averages 

wd wd 

Duration 

of 

Study 

months 

No. of 

Residences 

Study 

36 - 66 

49 

22 

Linaweaver, et al. (1) 

18 - 69 

44 

4 

18 

Anderson and Watson (2) 

25 - 65 

53 

2-12 

3 

Watson, et al. (3) 

37.8 - 101.6 

52 

6 

8 

26.3 - 65.4 

41.4 

24 

5 

ul Cohen and Wallman (4) 

Iv 

Laak (5) 

31.8 - 82.5 

44.5 

0.5 

5 

Bennett and Linstedt (6) 

25.4 - 56.9 

42.6 

1 

11 

Siegrist, et al. (7) 

8 - 71 

36 

12 

21 

Otis (8) 

42.3 

12 

16 

Duffy, et al. (9) 

Weighted Average 44

FIGURE 4-l 

FREQUENCY DISTRIBUTION FOR AVERAGE DAILY 

RESIDENTIAL WATER USE/WASTE FLOWS 

I I 1 I I I 

I I I I I I I I I I I I I I I 

1 2 5 10 20 3040506070 80 90 95 98 99 

Flow Values Less than or Equal to Stated Flow Value (%) 

Note: Based on the average daily flow measured 

for each of the 71 residences studied in (2) (3) (4) 

(5) (6) (7) (8). 

53

TABLE 4-2 

RESIDENTIAL WATER USE BY ACTIVITYa 

Activity Gal/use Uses/cap/day wdb 

Toilet Flush 4.3 

4.0 - 5.0 

Bathing 24.5 

21.4 - 27.2 

Clotheswashing 37.4 

33.5 - 40.0 

Dishwashing 8.8 

7.0 - 12.5 

Garbage Grinding 2.0 

2.0 - 2.1 

Miscellaneous 

Total 

3.5 

2.3 - 4.1 

0.43 

0.32 - 0.50 

0.29 

0.25 - 0.31 

0.35 

0.15 - 0.50 

0.58 

0.4 - 0.75 

a Mean and ranges of results reported in (4)(5)(6)(7)(10). 

b gpcd may not equal gal/use multiplied by uses/cap/day due to 

difference in the number of study averages used to compute the 

mean and ranges shown. 

54 

16.2 

9.2 - 20.0 

9.2 

6.3 - 12.5 

10.0 

7.4 - 11.6 

3.2 

1.1 - 4.9 

1.2 

0.8 - 1.5 

6.6 

5.7 - 8.0 

45.6 

41.4 - 52.0

extreme, however, minimum and maximum daily flows of 0% and 900% of the 

average daily flow may be encountered (2)(3)(12). 

b. Minimum and Maximum Hourly Flows 

Minimm hourly flows of zero are typical. Maximlan hourly flows are more 

difficult to quantify accurately. Based on typical fixture and appli- 

ance usage characteristics, as well as an analysis of residential water 

usage demands, maximum hourly flows of 100 gal/hr (380 l/hr) can occur 

(2)(131. Hourly flows in excess of this can occur due to plumbing fix- 

ture and appliance misuse or malfunction (e.g., faucet left on or worn 

toilet tank flapper). 

c. Instantaneous Peak Flows 

The peak flow rate from a residential dwelling is a function of the 

characteristics of the fixtures and appliances present and their posi- 

tion in the overall plumbing system layout. The peak discharge rate 

from a given fixture/appliance is typically around 5 gal/minute (gpml 

(0.3 liters/set), with the exception of the tank-type water closet which 

discharges at a peak flow of up to 25 gpm (1.6 l/set). The use ,of 

several fixtures/appliances simultaneously can increase the total flow 

rate from the isolated fixtures/appliances. However, attenuation occur- 

ring in the residential drainage network tends to decrease the peak flow 

rates in the sewer exiting the residence. 

Although field data are limited, peak discharge rates from a single- 

family dwelling of 5 to 10 gpm (0.3 to 0.6 l/set) can be expected. For 

multi-family units, peak rates in excess of these values commonly occur. 

A crude estimate of the peak flow in these cases can be obtained using 

the fixture-unit method described in Section 4.3.1.2. 

4.2.2 Wastewater Quality 


The characteristics of typical residential wastewater are outlined in 

Table 4-3, including daily mass loadings and pollutant concentrations. 

The wastewater characterized is typical of residential dwellings 

equipped with standard water-using fixtures and appliances (excluding 

garbage disposals) that collectively generate approximately 45 gpcd (170 

lpcd). 

55

TABLE 4-3 

CHARACTERISTICS OF TYPICAL RESIDENTIAL WASTEWATERa 

Parameter Mass Loading 

whWdw 

Concentration 

5 11 

Total Solids 115 - 170 680 - 1000 

Volatile Solids 65 - 85 380 - 500 

Suspended Solids 35 - 50 200 - 290 

Volatile Suspended Solids 25 - 40 150 - 240 

BOD5 35 - 50 200 - 290 

Chemical Oxygen Demand 115 - 125 680 - 730 

Total Nitrogen 6 - 17 35 - 100 

Ammonia 1 -3 6 - 18 

Nitrites and Nitrates 4 -4 

Total Phosphorus 3-5 18 - 29 

Phosphate 1 -4 6 - 24 

Total Coliformsb 1010 - 1012 

Fecal Coliformsb 108 - 1010 

a For typical residential dwellings equipped with standard water-using 

fixtures and appliances (excluding garbage disposals) generating 

approximately 45 gpcd (170 lpcd). Based on the results presented in 

(5)(6)(7)(10)(13). 

b Concentrations presented in organisms per liter. 

56

4i2.2.2 Individual Activity Contributions 

Residential water-using activities contribute varying amounts of pollu- 

tants to the total wastewater flow. The individual activities may be 

grouped into three major wastewater fractions: (1) garbage disposal 

wastes, (2) toilet wastes, and (3) sink, basin, and appliance waste- 

waters. A summary of the average contribution of several key pollutants 

in each of these three fractions is presented in Tables 4-4 and 4-5. 

With regard to the microbiological characteristics of the individual 

waste fractions, studies have demonstrated that the wastewater from 

sinks, basins, and appliances can contain significant concentrations of 

indicator organisms as total and fecal coliforms (14)(15)(16)(17). 

Traditionally, high concentrations of these organisms have been used to 

assess the contamination of a water or wastewater by pathogenic organ- 

isms. One assumes, therefore, that these wastewaters possess some po- 

tential for harboring pathogens. 

4.2.2.3 Wastewater Quality Variations 

Since individual water-using activities occur intermittently and contri- 

bute varying quantities of pollutants, the strength of the wastewater 

generated from a residence fluctuates with time. Accurate quantifica- 

tion of these fluctuations is impossible. An estimate of the type of 

fluctuations possible can be derived from the pollutant concentration 

information presented in Table 4-5 considering that the activities 

included occur intermittently. 

4.3 Nonresidential Wastewater Characteristics 

The rural population, as well as the transient population moving through 

the rural areas, is served by a wide variety of isolated commercial 

establishments and facilities. For many establishments, the wastewater- 

generating sources are sufficiently similar to those in a residential 

dwelling that residential wastewater characteristics can be applied. 

For other establishments, however, the wastewater characteristics can be 

considerably different from those of a typical residence. 

Providing characteristic wastewater loadings for "typical" non-residen- 

tial establishments is a very complex task due to several factors. 

First, there is a relatively large number of diverse establishment cate- 

gories (e.g., bars, restaurants, drive-in theaters, etc.). The inclu- 

sion of potentially diverse establishments within the same category 

produces a potential for large variations in waste-generating sources 

57

Parameter 

BOD5 

Suspended 

Solids 

Nitrogen 

Phosphorus 

TABLE 4-4 

POLLUTANT CONTRIBUTIONS OF MAJOR RESIDENTIAL 

WASTEWATER FRACTIONSa (gm/cap/day) 

Garbage 

Disposal Toilet 

Basins, 

Sinks, Approximate 

Appliances Total 

18.0 16.7 28.5 63.2 

10.9 - 30.9 6.9 - 23.6 24.5 - 38.8 

26.5 27.0 17.2 70.7 

15.8 - 43.6 12.5 - 36.5 10.8 - 22.6 

0.6 8.7 1.9 11.2 

0.2 - 0.9 4.1 - 16.8 1.1 - 2.0 

0.1 1.2 2.8 4.0 

0.1 - 0.1 0.6 - 1.6 2.2 - 3.4 

a Means and ranges of results reported in (5)(6)(7)(10)(14) 

Parameter 

BOD5 

Suspended 

Solids 

Nitrogen 

Phosphorus 

TABLE 4-5~ 

POLLUTANT CONCENTRATIONS OF MAJOR RESIDENTIAL 

WASTEWATER FRACTIONSa (mg/l) 

Garbage 

Disposal Toilet 

Basins, Sinks, Combined 

Appliances Wastewater 

2380 280 260 360 

3500 450 160 400 

79 140 17 63 

13 20 26 23 

a Based on the average results presented in Table 4-4 and the 

following wastewater flows: Garbage disposal - 2 gpcd (8 lpcd); 

toilet - 16 gpcd (61 lpcd); basins, sinks and appliances - 29 gpcd 

(110 lpcd); total - 47 gpcd (178 lpcd). 

58

and the resultant wastewater characteristics. Further, many intangible 

influences such as location, popularity, and price may produce substan- 

tial wastewater variations between otherwise similar establishments. 

Finally, there is considerable difficulty in presenting characterization 

data in units of measurement that are easy to apply, yet predictively 

accurate. (For example, at a restaurant, wastewater flow in gal/seat is 

easy to apply to estimate total flow, but is less accurate than if 

gal/meal served were used.) 

In this section, limited characterization data for nonresidential estab- 

lishments, including commercial establishments, institutional facili- 

ties, and recreational areas, are presented. These data are meant to 

serve only as a guide, and as such should be applied cautiously. Wher- 

ever possible, characterization data for the particular establishment in 

question, or a similar one, in the vicinity, should be obtained. 

4.3.1 Wastewater Flow 


Typical daily flows from a variety of commercial, institutional, and 

recreational establishments are presented in Tables 4-6 to 4-8. 

4.3.1.2 Wastewater Flow Variation 

The wastewater flows from nonresidential establishments are subject to 

wide fluctuations with time. While difficult to quantify accurately, an 

estimate of the magnitude of the fluctuations, including minimum and 

maximum flows on an hourly and daily basis, can be made if consideration 

is given to the characteristics of the water-using fixtures and appli- 

ances, and to the operational characteristics of the establishment 

(hours of operation, patronage fluctuations, etc.). 

Peak wastewater flows can be estimated utilizing the fixture-unit method 

(19) (20). As originally developed, this method was based on the premise 

that under normal usage, a given type of fixture had an average flow 

rate and duration of use (21)(22). One fixture unit was arbitrarily set 

equal to a flow rate of 7.5 gpm (0.5 l/set), and various fixtures were 

assigned a certain number of fixture units based upon their particular 

characteristics (Table 4-9). Based on probability studies, relation- 

ships were developed between peak water use and the total number of fix- 

ture units present (Figure 4-2). 

59

Airport 

TABLE 4-6 

TYPICAL WASTEWATER FLOWS FROM COMMERCIAL SOURCES (18) 

Source 

Automobile Service Station 

Bar 

Hotel 

Industrial Building 

(excluding industry and 

cafeteria) 

Laundry (self-service) 

Motel 

Motel with Kitchen 

Office 

Restaurant 

Rooming House 

Store, Department 

Shopping Center 

Unit 

Passenger 

Vehicle Served 

Employee 

Customer 

Employee 

Guest 

Employee 

Employee 

Machine 

Wash 

Person 

Person 

Employee 

Meal 

Resident 

Toilet room 

Employee 

Parking Space 

Employee 

60 


Range Typical 

gpdlunit 

2.1 - 4.0 

7.9 - 13.2 

9.2 - 15.8 

lb"6 : 1E 

39.6 - 58.0 

7.9 - 13.2 

7.9 - 17.2 

475 - 686 

47.5 - 52.8 

23.8 - 39.6 

50.2 - 58.1 

7.9 - 17.2 

2.1 - 4.0 

23.8 - 50.1 

423 - 634 

7.9 - 13.2 

0.5 - 2.1 

7.9 - 13.2 

2.6 

10.6 

13.2 

2.1 

13.2 

50.1 

10.6 

14.5 

580 

50.1 

31.7 

52.8 

14.5 

2.6 

39.6 

528 

10.6 

1.1 

10.6

TABLE 4-7 

TYPICAL WASTEWATER FLOWS FROM INSTITUTIONAL SOURCES (18) 

Source 

Hospital, Medical 

Hospital, Mental 

Prison 

Rest Home 

School, Day: 

With Cafeteria, Gym, 

Showers 

With Cafeteria Only 

Without Cafeteria, Gym, 

Showers 

School, Boarding 

Unit 

Bed 

Employee 

Bed 

Employee 

Inmate 

Employee 

Resident 

Employee 

Student 

Student 

Student 

Student 

61 


Range Typical 

gpd/unit 

132 - 251 172 

5.3 - 15.9 10.6 

79.3 - 172 106 

5.3 - 15.9 10.6 

79.3 - 159 119 

5.3 - 15.9 10.6 

52.8 - 119 92.5 

5.3 - 15.9 10.6 

15.9 - 30.4 21.1 

10.6 - 21.1 15.9 

5.3 - 17.2 10.6 

52.8 - 106 74.0

TABLE 4-8 

TYPICAL WASTEWATER FLOWS FROM RECREATIONAL SOURCES (18) 

Source 

Apartment, Resort 

Cabin, Resort 

Cafeteria 

Campground (developed) 

Cocktail Lounge 

Coffee Shop 

Country Club 

Day Camp (no meals) 

Dining Hall 

Dormitory, Bunkhouse 

Hotel, resort 

Laundromat 

Store Resort 

Swimming Pool 

Theater 

Visitor Center 

Person 

Person 

Unit 

Customer 

Employee 

Person 

Seat 

Customer 

Employee 

Member Present 

Employee 

Person 

Meal Served 

Person 

Person 

Machine 

Customer 

Employee 

Customer 

Employee 

Seat 

Visitor 

62 


Range Typical 

gpd/unit 

52.8 - 74 

34.3 - 50.2 

::ij : 13.2 2.6 

21.1 - 39.6 

13.2 - 26.4 

4.0 - 7.9 

7.9 - 13.2 

66.0 - 132 

10.6 - 15.9 

10.6 - 15.9 

4.0 - 13.2 

19.8 - 46.2 

39.6 - 63.4 

476 - 687 

1.3 - 5.3 

7.9 - 13.2 

5.3 - 13.2 

7.9 - 13.2 

2.6 - 4.0 

4.0 - 7.9 

58.1 

42.3 

1.6 

10.6 

31.7 

19.8 

12 

106 

13.2 

13.2 

7.9 

39.6 

52.8 

581 

2.6 

10.6 

10.6 

10.6 

2.6 

5.3

TABLE 4-9 

FIXTURE-UNITS PER FIXTURE (19) 

Fixture Type 

One bathroom group consisting of tank-operated water 

closet, lavatory, and bathtub or shower stall 

Bathtub (with or without overhead shower) 

Bidet 

Combination sink-and-tray 

Combination sink-and-tray with food-disposal unit 

Dental unit or cuspidor 

Dental lavatory 

Drinking fountain 

Dishwasher, domestic 

Floor drains 

Kitchen sink, domestic 

Kitchen sink, domestic, with food waste grinder 

Lavatory 

Lavatory 

Lavatory, barber, beauty parlor 

Lavatory, surgeon's 

Laundry tray (1 or 2 compartments) 

Shower stall, domestic 

Showers (group) per head 

Sinks 

Surgeon's 

Flushing rim (with valve) 

Service (trap standard) 

Service (P trap) 

Pot, scullery, etc. 

Urinal, pedestal, syphon jet, blowout 

Urinal, wall lip 

Urinal stall, washout 

Urinal trough (each 2-ft section) 

Wash sink (circular or multiple) each set of faucets 

Water closet, tank-operated 

Water closet, valve-operated 

63 

Fixture-Units 

2” 

3 

3 

4 

1 

1:2 

2 

1 

2 

: 

2 

2 

2 

2 

2 

3 

3 

3” 

2 

4 

8 

4 

i! 

2 

4 

8

FIGURE 4-2 

PEAK DISCHARGE VERSUS FIXTURE UNITS PRESENT (22) 

I I I I I I I I I I I 

Note: Curves show probable amount of time indicated peak flow will 

be exceeded during a period of concentrated fixture use. 

450 - 

400 - 

350 - 

5 

& 300 _ -System in which flush 

valves predominate 

i 

ii 250 - System in which flush 

Y 

tanks predominate 

: 

a 

al 

200 - 

n 

: 150- 

& 

loo- 

01 I I I I I I I I I I I I 

0 2 4 6 8 10 12 14 16 18 20 22 

Fixture Units on System (Hundreds)

4.3.2 Wastewater Quality 

The qualitative characteristics of the wastewaters generated by non- 

residential establishments can vary significantly between different 

types of establishments due to the extreme variation which can exist in 

the waste generating sources present. Consideration of the waste-gen- 

erating sources present at a particular establishment can give a general 

idea of the character of the wastewater, and serve to indicate if the 

wastewater will contain any problem constituents, such as high grease 

levels from a restaurant or lint fibers in a laundromat wastewater. 

If the waste-generating sources present at a particular establishment 

are similar to those typical of a residential dwelling, an approximation 

of the pollutant mass loadings and concentrations of the wastewater pro- 

duced may be derived using the residential wastewater quality data pre- 

sented in Tables 4-3 to 4-5. For establishments where the waste-gener- 

ating sources appear significantly different from those in a residential 

dwelling, or where more refined characterization data are desired, a de- 

tailed review of the pertinent literature, as well as actual wastewater 

sampling at the particular or a similar establishment, should be conduc- 

ted. 

4.4 Predicting Wastewater Characteristics 

4.4.1 General Considerations 

4.4.1.1 Parameter Design Units 

In characterizing wastewaters, quantitative and qualitative character- 

istics are often expressed in terms of other parameters. These para- 

meter design units, as they may be called, vary considerably depending 

on the type of establishment considered. For residential dwellings, 

daily flow values and pollutant contributions are expressed on a per 

person (capita) basis. Applying per capita data to predict total resi- 

dential wastewater characteristics requires that a second parameter be 

considered, namely, the number of persons residing in the residence. 

Residential occupancy typically ranges from 1.0 to 1.5 persons per bed- 

room. Although it provides for a conservative estimate, the current 

practice is to assume that maximum occupancy is two persons per bedroom. 

For nonresidential establishments, wastewater characteristics are 

expressed in terms of a variety of units. Although per capita units are 

employed, a physical characteristic of the establishment, such as per 

seat, per car stall, or per square foot, is more commonly used. 

65

4.4.1.2 Factors of Safety 

To account for the potential variability in the wastewater character- 

istics at a particular dwelling or establishment, versus that of the 

average, conservative predictions or factors of safety are typically 

utilized. These factors of safety can be applied indirectly, through 

choice of the design wastewater characteristics and the occupancy pat- 

terns, as well as directly through an overall factor. For example, if 

an average daily flow of 75 gpcd (284 lpcd) and an occupancy of two 

persons per bedroom were selected, the flow prediction for a three- 

bedroom home would include a factor of safety of approximately 3 when 

compared to average conditions (i.e., 45 gpcd Cl70 lpcdl and 1 .person 

per bedroom). If a direct factor of safety were also applied (e.g., 

1.251, the total factor of safety would increase to approximately 3.75. 

Great care must be exercised in predicting wastewater characteristics so 

as not to accumulate multiple factors of safety which would yield an 

extremely overconservative estimate. 

4.4.2 Strategy for Predicting Wastewater Characteristics 

Predicting wastewater characteristics from rural developments can be a 

complex task. Following a logical step-by-step procedure can help 

simplify the characterization process and render the estimated waste- 

water characteristics more accurate. A flow chart detailing a procedure 

for predicting wastewater characteristics is presented in Figure 4-3. 

66

* 

FIGURE 4-3 

STRATEGY FOR PREDICTING WASTEWATER CHARACTERISTICS 

Determine Primary Function of Facility 

(e.g., Stngle-Family Home, Restaurant...) 

Identify Intended Application of Wastewater 

Identify Wastewater Characterization 

Data Needed (e.g.. Q. BODr...) 

Determine Physical Charactertstics of Faciltty 

0 Wastewater Generating Fixtures and Appliances 

l Parameter Destgn Units (e.g., Bedrooms, 

Seating Spaces...) 

0 Occupancy or Operation Patterns (e.g.. 

Seasonal Home. Hours of Operation...) 

Obtain Characterizatron Data from Literature 

0 Tables and Text of This Chapter 

0 Reference and Bibliography Attached 

tc This Chapter 

0 Other Sources 

Gather Existing Measured Characterization Data 

Applicable to Facility 

0 Water Meter Records 

0 Holding Tank Pumpage Records 

0 Other 

4 

1 

Evaluate Available Data 

0 Select Data Judged Most Accurate 

0 Determtne if Needed Data has been Obtained 

Calculate Waste Load Characteristics Conduct Characterization 

(e.g., 45 GPCD x 2 CAP/Bedroom x Field Studies at Facility 

2 Bedrooms = 180 GPD) in Question or a Very 

’ Similar One 

I- - 

Apply Overall Factor of Safety as Required 

by Intended Appbcation of Data 

Estimate Wastewater 


t 

67


1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

Linaweaver, F. P., Jr., J. C. Geyer, and J. B. Wolff. A Study of 

Residential Water Use. .Department of Environmental Studies, Johns 

Hopkins University, Baltimore, Maryland, 1967. 105 pp. 

Anderson, J. S., and K. S. Watson. Patterns of Household Usage. 

J. Am. Water Works Assoc., 59:1228-1237, 1967. 

Watson, K. S., R. P. Farrell, and J. S. Anderson. The Contribution 

from the Individual Home to the Sewer System. J. Water Pollut. 

Control Fed., 39:2039-2054, 1967. 

Cohen, S., and H. Wallman. Demonstration Of Waste Flow Reduction 

From Households. EPA 670/2-74-071, NTIS Report No. PB 236 904, 

1974. 111 pp. 

Laak, R. Relative Pollution Strengths of Undiluted Waste Materials 

Discharged in Households and the Dilution Waters Used for Each. 

Manual of Grey Water Treatment Practice - Part II, Monogram Indus- 

tries, Inc., Santa Monica, California, 1975. 

Bennett, E. R., and E. K. Linstedt. Individual Home Wastewater 

Characterization and Treatment. Completion Report Series No. 66, 

Environmental Resources Center, Colorado State University, Fort 

Collins, 1975. 145 pp. 

Siegrist, R. L., M. Witt, and W. C. Boyle. Characteristics of 

Rural Household Wastewater. J. Env. Eng. Div., Am. Sot. Civil 

Eng., 102:553-548, 1976. 

Otis, R. J. An Alternative Public Wastewater Facility for a Small 

Rural Community. Small Scale Waste Management Project, University 

of Wisconsin, Madison, 1978. 

Duffy, C. P., et al. Technical Performance of the Wisconsin Mound 

System for On-Site Wastewater Disposal - An Interim Evaluation. 

Presented in Preliminary Environmental Report for Three Alternative 

Systems (Mounds) for On-site Individual Wastewater Disposal in 

Wisconsin. Wisconsin Department of Health and Social Services, 

December 1978. 

Ligman, K., N. Hutzler, and W. C. Boyle. Household Wastewater 

Characterization. J. Environ. Eng. Div., Am. Sot. Civil Eng., 

150:201-213, 1974. 

Weickart, R. F. Effects of Backwash Water and Regeneration Wastes 

From Household Water Conditioning Equipment on Private Sewage Dis- 

posal Systems. Water Quality Association, Lombard, Illinois, 1976. 

68

12. Witt, M. Water Use in Rural Homes. M.S. study. University of 

Wisconsin-Madison, 1974. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

21. 

22. 

Jones, E. E., Jr. Domestic Water Use in Individual Homes and 

Hydraulic Loading of and Discharge from Septic Tanks. In: Pro- 

ceedings of the National Home Sewage Disposal Symposium,Chicago, 

December 1974. American Society of Agricultural Engineers, St. 

Joseph, Michigan. pp. 89-103. 

Olsson, E., L. Karlgren, and V. Tullander. Household Wastewater. 

National Swedish Institute for Building Research, Stockholm, Swe- 

den, 1968. 

Hypes, W. D., C. E. Batten, and J. R. Wilkins. The Chemical/ 

Physical and Microbiological Characteristics of Typical Bath and 

Laundry Wastewaters. NASA TN D-7566, Langley Research Center, 

Langley Station, Virginia, 1974. 31 pp. 

Small Scale Waste Management Project, University of Wisconsin, 

Madi son. Management of Small Waste Flows. EPA 600/2-78-173, NTIS 


Brandes, M. Characteristics of Effluents From Separate Septic 

Tanks Treating Grey and Black Waters From the Same House. J. Water 

Pollut. Control Fed., 50:2547-2559, 1978. 

Metcalf and Eddy, Inc. Wastewater Engineering: Treatment/ 

Disposal/Reuse. 2nd ed. McGraw-Hill, New York, 1979. 938 pp. 

Design and Construction of Sanitary and Storm Sewers. Manual of 

Practice No. 9. Water Pollution Control Federation, Washington, 

D.C., 1976. 369 pp. 

Uniform Plumbing Code. International Association of Plumbing and 

Mechanical Officials, Los Angeles, California, 1976. 

Hunter, R. B. Method of Estimating Loads in Plumbing Systems. 

Building Materials and Structures Report BMS65, National Bureau of 

Standards, Washington, D.C., 1940. 23 pp. 

Hunter, R. B. Water Distribution Systems for Buildings. Building 

Materials and Structures Report BMS79, National Bureau of Stan- 

dards, Washington, D.C., 1941. 

69


CHAPTER 5 

WASTEWATER MODIFICATION 

The characteristics of the influent wastewater can have a major impact 

on most any onsite treatment and disposal/reuse system. To enhance con- 

ventional strategies, and to encourage new ones, methods can be used to 

modify the typical characteristics of the influent wastewater. 

Methods for wastewater modification have been developed as part of 

three, basic interrelated strategies: water conservation and wastewater 

flow reduction, pollutant mass reduction, and onsite containment for 

offsite disposal. Each strategy attempts to reduce the flow volume or 

to decrease the mass of key pollutants such as oxygen-demanding sub- 

stances, suspended solids, nutrients, and pathogenic organisms in the 

influent wastewater to the onsite disposal system. 

Although the primary thrust of this chapter is directed toward res-i- 

dential dwellings, many of the concepts and techniques presented have 

equal or even greater application to nonresidential establishments. 

Good practice dictates that water conservation/flow reduction be 

employed to the maximum extent possible in a dwelling served by an 

onsite wastewater system. 

At the onset, there are several general considerations regarding waste- 

water modification. First, there are a nLPnber of methods available, 

including a wide variety of devices, fixtures, appliances, and systems. 

Further, the nLanber of methods and the diversity of their characteris- 

tics is ever growing. In many cases, the methods involve equipment 

manufactured by one or more companies as proprietary products. In this 

chapter, only generic types of these products are considered. Also, 

many methods and system components are presently in various stages of 

development and/or application; therefore, only preliminary or projected 

operation and performance information may be available. Finally, the 

characteristics of many of the methods discussed may result in their 

nonconformance with existing local plumbing codes. 

70

5.2 Water Conservation and Wastewater Flow Reduction 

An extensive array of techniques and devices are available to reduce the 

average water use and concomitant wastewater flows generated by indivi- 

dual water-using activities and, in turn, the total effluent from the 

residence or establishment. The diversity of present wastewater flow 

reduction methods is illustrated in Table 5-1. As shown, the methods 

may be divided into three major groups: (1) elimination of nonfunc- 

tional water use, (2) water-saving devices, fixtures, and appliances; 

and (3) wastewater recycle/reuse systems. 

5.2.1 Elimination of Nonfunctional Water Use 

Wasteful water use habits can occur with most water-using activities. A 

few illustrative examples include using a toilet flush to dispose of a 

cigarette butt, allowing the water to run while brushing teeth or shaving, 

or operating a clotheswasher or dishwasher with only a partial 

load. Obviously, the potential for wastewater flow reductions through 

elimination of these types of wasteful use vary tremendously between 

homes, 

habits. 

from minor to significant reductions, depending on existing 

5.2.1.1 Improved Plumbing and Appliance Maintenance 

Unseen or apparently insignificant leaks from household fixtures and ap- 

pliances can waste large volumes of water and generate similar quanti- 

ties of wastewater. Most notable in this regard are leaking toilets and 

dripping faucets. For example, a steadily dripping faucet can waste up 

to several hundred gallons per day. 

5.2.1.2 Maintain Nonexcessive Water Supply Pressure 

The water flow rate through sink and basin faucets, showerheads, and 

similar fixtures is highly dependent on the water pressure in the water 

su ply line. For most residential uses, a pressure of 40 psi (2.8 kg/ 

cm 

!2 

1 is adequate. Pressure in excess of this can result in unnecessary 

water use and wastewater generation. To illustrate, the flow rate 

through a typical faucet ope!ed fully is about 40% higher at 3 supply 

pressure of 80 psi (5.6 kg/cm 1 versus that at 40 psi (2.8 kg/cm 1. 

71

TABLE 5-l 

EXAMPLE WASTEWATER FLOW REDUCTION METHODS 

I. Elimination of Nonfunctional Water Use 

A. Improved water use habits 

B. Improved plumbing and appliance maintenance 

c. Nonexcessive water supply pressure 

II. Water-Saving Devices, Fixtures, and Appliances 

A. Toilet 

1. Water carriage toilets 

a. Toilet tank inserts 

b. Dual-flush toilets 

c. Water-saving toilets 

d. Very low-volume flush toilets 

(1) Wash-down flush 

(21 Mechanically assisted 

o Pressurized tank 

o Compressed air 

0 Vacuum 

o Grinder 

2. Non-water carriage toilets 

a. Pit privies 

b. Composting toilets 

c. Incinerator toilets 

d. Oil-carriage toilets 

B. Bathing devices, fixtures, and appliances 

1. Shower flow controls 

2. Reduced-flow showerheads 

3. On/Off showerhead valves 

4. Mixing valves 

5. Air-assisted low-flow shower system 

C. Clotheswashing devices, fixtures, and appliances 

1. Front-loading washer 

2. Adjustable cycle settings 

3. Washwater recycle feature 

D. Miscellaneous 

1. Faucet inserts 

2. Faucet aerators 

3. Reduced-flow faucet fixtures 

4. Mixing valves 

5. Hot water pipe insulation 

6. Pressure-reducing valves 

III. Wastewater Recycle/Reuse Systems 

A. Bath/Laundry wastewater recycle for toilet flushing 

Toilet wastewater recycle for toilet flushing 

c": Combined wastewater recycle for toilet flushing 

D. Combined wastewater recycle for several uses 

72

5.2.2 Water-Saving Devices, Fixtures, and Appliances 

The quantity of water traditionally used by a given water-using fixture 

or appliance is often considerably greater than actually needed. 

Certain tasks may even be accomplished without the use of water. As 

presented in Table 4-2, over 70% of a typical residential dwelling's 

wastewater flow volume is collectively generated by toilet flushing, 

bathing, and clotheswashing. Thus, efforts to accomplish major 

wastewater flow reductions should be directed toward these three 

activities. 

5.2.2.1 Toilet Devices and Systems 

Each flush of a conventional water-carriage toilet uses between 4 and 7 

gal (15 and 26 1) of water depending on the model and water supply 

pressure. On the average, a typical flush generates approximately 4.3 

gal (16 1) of wastewater. When coupled with 3.5 uses/cap/day, a daily 

wastewater flow of approximatley 16 gpcd (61 lpcd) results (Table 4-2). 

A variety of devices have been developed for use with a conventional 

flush toilet to reduce the volume of water used in flushing. 

Additionally, alternatives to the conventional water-carriage toilet are 

available, certain of which use little or no water to transport human 

wastewater products. Tables 5-2 and 5-3 present a summary of a variety 

of toilet devices and systems. Additional details regarding the 

non-water carriage toilets may be found elsewhere (l)(2)(3)(4)(5). 

5.2.2.2 Bathing Devices and Systems 

Although great variation exists in the quantity of wastewater generated 

by a bath or shower, typical values include approximatley 25 gal (95 1) 

per occurrence coupled with a 0.4 use/capita/day frequency to yield a 

daily per capita flow of about 10 gal (38 1 ) (Table 4-2). The majority 

of devices available to reduce bathing wastewater flow volumes are 

concentrated around the activity of showering, with their objective 

being to reduce normal 4- to lo-gal/min (0.25 to 0.63 l/set) showering 

flow rate. Several flow reduction devices and systems for showering are 

characterized in Table 5-4. The amount of total wastewater flow 

reduction accomplished with these devices is highly dependent on 

individual user habits. Reductions vary from a negative value to as 

much as 12% of the total wastewater volume. 

73

TABLE 5-2 

WASTEWATER FLOW REDUCTION - WATER CARRIAGE TOILETS AND SYSTEMS 

Total Flow 

Reductionb 

Water Use 

Per Event 

gal 

Operation and 

Maintenance 

Development 

Stagea Considerations 

Description 

Generic Type 

% 

wed 

4-5 Device must be Post-installation and 3.3-3.8 1.8-3.5 4-8 

compatible with periodic inspections 

existing toilet and to insure proper 

not interfere with positioning. 

flush mechanism. 

Toilet with Displacement devices 

Tank Inserts placed into storage 

tank of conventional 

toilets to reduce 

volume but not height 

of stored water. 

Installation by 

owner. 

Varieties: Plastic 

bottles, flexible 

panels, drums or 

plastic bags. 

6-15 

Device must be Post-installation and 2.5-4.3 3.0-7-o 

compatible with 

periodic inspections 

existing toilet and to insure proper 

not interfere with positioning and 

flush mechanism. 

functioning. 

3 

Devices made for use 

with conventional 

flush toilets; enable 

user to select from 

two or more flush 

volumes based on 

solid or liquid waste 

materials. 

Dual Flush 

Toilets 

-4 

P 

Installation by 

owner. 

Varieties: Many 

Interchangeable with Essentially the same 3.0-3.5 2.8-4.6 6-10 

conventional fixture. as for a conventional 

unit. 

Requires pressurized 

water supply. 

5 

Water-Saving Variation of 

Toilets conventional flush 

toilet fixture; 

similar in appearance 

and operation. 

Redesigned flushing 

rim and priming jet 

to initiate siphon 

flush in smaller 

trapway with less 

water. 


manufacturers but 

units similar.

TABLE 5-2 (continued) 

Total Flo 

Reduction 'L: 


Maintenance 

Application 

Considerations 

Development 

Stagea 

Generic Type Description 

% 

wed 

Water Use 

Per Event 

gal 

0.8-1.6 9.4-12.2 21-27 

Similar to 

conventional toilet, 

but more frequent 

cleaning possible. 

3-4 Rough-in for unit may 

be nonstandard. 

Drain line slope and 

lateral run 

restrictions. 

Washdown Flush Flushing uses only 

Toilets water, but 

substantially less 

due to washdown 

flush. 

Varieties: Few. 

Requires pressurized 

water supply. 

2.0-2.5 6.3-8-O 14-18 

3 Compatible with most Similar to 

any conventional conventional toilet 

toilet unit. fixture. 

Specially designed 

toilet tank to 

pressurize air 

contained in toilet 

tank. Upon flushing, 

the compressed air 

propels water into 

bowl at increased 

velocity. 

Pressurized 

Tank 

Increased noise 

level. 

Water supply pressure 

of 35 to 120 psi. 

Varieties: Few. 

0.5 13.3 30 

3-4 Interchangeable with Periodic maintenance 

rough-in for of compressed air 

conventional fixture. source. 

Power use - 0.002 KwH 

per use. 

Requires source of 

compressed air; 

bottled or air 

compressor. 

Compressed Similar in appearance 

Air-Assisted and user operation to 

Flush Toilets conventional toilet; 

specially designed to 

utilize compressed 

air to aid in 

flushing. 

Varieties: Few 

If air compressor, 

need power source.


Total Flow 

Reductionh 

Water Use 

Per Event 

gal 


Maintenance 

Application 


Development 

Stagea 

Generic Type Description 

% 

gwd 

3 Application largely Periodic maintenance 0.3 14 3 

for multi-unit toilet of vacuum pump. 

installations 

Power use = 0.002 KwH 

Above floor, rear per use. 

discharge. 

Drain pipe may be 

horizontal or 

inclined. 

Vacuum- Similar in appearance 

Assisted Flush and user operation to 

Toilets conventional toilet; 

specially designed 

fixture is connected 

to vacuum system 

which assists a small 

volume of water in 

flushing. 

Varieties: Several. 

Requires vacuum pump. 

Requires power 

Source. 

a 1 = Prototype developed and under evaluation. 

2 = Development complete, commercial production initiated, not locally available. 

3 = Fully developed, limited use, not locally available, mail order purchase likely. 

4 = Fully developed, limited use, locally available from plumbing supply houses or hardware stores. 

5 = Fully developed, widespread use, locally available from plumbing supply houses or hardware stores. 

b Compared to conventional toilet usage (4.3 gal/flush, 3.5 uses/cap/day, and a total daily flow of 45 gpcd)

Generic Typea Description 

Pit Privy Hand-dug hole in the 

ground covered with a 

squatting plate or 

stool/seat with an 

enclosing house. 

Composting 

Privy 

Composting- 

Small 

Composting- 

Large 

TABLE 5-3 

WASTEWATER FLOW REDUCTION - NON-WATER CARRIAGE TOILETS 

May be sealed vault 

rather than dug hole. 

Similar to pit privy 

except organic matter 

is added after each 

use. When pit is 

full it is allowed to 

compost for a period 

of about 12 months 

prior to removal and 

use as soil 

amendment. 

Small self-contained 

units accept toilet 

wastes only and 

utilize the addition 

of heat in 

combination with 

aerobic biological 

activity to stabilize 

human excreta. 


Larger units'with a 

separated 

decomposition 

chamber. Accept 

toilet wastes and 

other organic matter, 

and over a long time 

period stabilize 

excreta through 

biological activity. 

Varieties: Several 

Develop- 

ment 

Stageb 

Application 


4 Requires same site 

conditions as for 

wastewater disposal 

(see Chapter 81, 

unless sealed vault. 

Handles only toilet 

wastes 

Outdoor installation. 

May be constructed by 

user. 

4 Can be constructed 

independent of site 

conditions if sealed 

vault. 


waste and garbage. 

May be constructed by 

user. 

Outdoor installation. 

Residuals disposal. 

3-4 Installation requires 

4-in. diameter roof 

vent. 


waste. 

Set usage capacity. 

Power required. 


3-4 Installation requires 

6- to 12-in. diameter 

roof vent and space 

beneath floor for 

decomposition 

chamber. 

77 

Handles toilet waste 

and some kitchen 

waste. \ 

Set usage capacity. 

May be difficult to 

retrofit. 



Maintenance 

When full, cover with 

2 ft of soil and 

construct new pit. 

Addition of organic 

natter after each 

use. 

Removal and 

disposal/reuse of 

composted material. 

Removal and disposal 

of composted material 

quarterly. 

Power use = 2.5 

KwH/day. 

Heat loss through 

vent. 

Periodic addition of 

organic matter. 

Removal of composted 

material at 6 to 24 

month intervals. 

Power use = 0.3 to 

1.2 KwH/day. 

Heat loss through 

vent.


Incinerator Small self-contained 

units which 

volatilize the 

organic components of 

human waste and 

evaporate the 

liquids. 



Develop- 

ment 

Stageb 

Oil Recycle Systems use a mineral 2 

oil to transport 

human excreta from a 

fixture (similar in 

appearance and use to 

conventional) to a 

storage tank. Oil is 

purified and reused 

for flushing. 

Varieties: few. 

Application 


3 Installation requires 

4-in. diameter roof 

vent. 


waste. 

Power or fuel 

required. 

Increased noise 

level. 


Requires separate Yearly removal and 

plumbing for toilet disposal of excreta 

fixture. in storage tank. 


retrofit. 


wastes 



Maintenance 

Weekly removal of 

ash. 

Semiannual cleaning 

and adjustment of 

burning assembly 

and/or heating 

elements. 

Power use = 1.2 KwH 

or 0.3 lb LP gas per 

use. 

Yearly maintenance of 

oil purification 

system by skilled 

technician. 


KwH/use. 

a None of these devices uses any water; therefore, the amount of flow reduction is equal to the 

amount of conventional toilet use: 16.2 gpcd or 36% of normal daily flow (45 qpcd). Significant 

quantities of pollutants (including N, BOD5, SS, P and pathogens) are therefore removed from 

wastewater stream. 

b 1 = Prototype developed and under evaluation. 

2 = Development complete; commercial production initiated, but distribution may be restricted; 

mail order purchase. 

3 = Fully developed; limited use, not locally available; mail order purchase likely. 

4 = Fully developed; limited use, available form local plumbing supply houses or hardware stores. 

5 = Fully developed; widespread use, available from local plumbing supply houses or hardware stores. 

78

TABLE 5-4 

WASTEWATER FLOW REDUCTION - BATHING DEVICES AND SYSTEMS 


Shower Flow Reduce flow rate by 

Control reducing the diameter 

Inserts and of supply line ahead 

Restrictors of shower head. 

Reduced-Flow 

Showerheads 

ON/OFF 

Showerhead 

Valve 

Thermostat- 

ically 

Controlled 

Mixing Valve 

Varieties: Many. 

Fixtures similar to 

conventional, except 

restrict flow rate. 


manufacturers, but 

units similar. 

Small valve device 

placed in the supply 

line ahead of 

showerhead, allows 

shower flow to be 

turned ON/OFF without 

readjustment of 

volume or 

temperature. 

Specifically designed 

valve controls 

temperature of total 

flow according to 

predetermined 

setting. Valve MY 

be turned ON/OFF 

without readjustment. 

Develop- 

ment 

Stageb 

4 

4-5 

79 

4 

3 

Application 


Compatible with most 

existing showerheads. 

Installed by user. 

Can match to most 

plumbing fixture 

appearance schemes. 


conventional 

plumbing. 


conventional plumbing 

and fixtures. 

May be installed by 

user. 


retrofit. 

Water Use 

-gTiir 

1.5-3.0 

1.5-3.0 

mm- 

--e

Generic Typea Descriptibn 

Pressure- 

Balanced 

Mixing 

Valve 

Air-Assisted 

Low-Flow 

Shower 

System 


valve maintains 

constant temperature 

of total flow 

regardless of 

pressure changes. 

Single control allows 

temperature to be 

preset. 


system uses 

compressed air to 

atomize water flow 

and provide shower 

sensation. 


Develop- 

ment 

Stageb 

Application 

Considerations Water Use 

gal/min 


conventional plumbing 

and fixtures. 

May be impossible to 

retrofit. 

Shower location ( 50 

feet of water heater. 

Requires compressed 

air source. 

Power source 

required. 

Maintenance of air 

compressor. 


KwHluse. 

a No reduction in pollutant mass; slight increase in pollutant concentration. 

b 1 = Prototype developed and under evaluation. 

2 = Development complete; commercial production initiated, but distribution may be 

restricted; mail order purchase. 

3 = Fully developed; limited use, not locally available; mail order purchase 

likely. 

4 = Fully developed; limited use, available from local plumbing supply houses or 

hardware stores. 

5 = Fully developed; widespread use, available from local plumbing supply houses or 

hardware stores. 

80 

--- 

0.5

5.2.2.3 Clotheswashing Devices and Systems 

The operation of conventional clotheswashers consumes varying quantities 

of water depending on the manufacturer and model of the washer and the 

cycle selected. For most, water usage is 23 to 53 gal (87 to 201 1) per 

usage. Based on home water use monitoring, an average water use/waste- 

water flow volume of approximately 37 gal (140 1) per use has been iden- 

tified, with the clotheswasher contributing about 10.0 gpcd (38 lpcd) or 

22% of the total daily water use/wastewater flow (Table 4-2). Practical 

methods to reduce these quantities are somewhat limited. Eliminating 

wasteful water use habits, such as washing with only a partial load, is 

one method. Front-loading model automatic washers can reduce water used 

for a comparable load of clothes by up to 40%. In addition, wastewater 

flow reductions may be accomplished through use of a clotheswasher with 

either adjustable cycle settings for various load sizes or a wash water 

recycle feature. 

The wash water recycle feature is included as an optional cycle setting 

on several commercially made washers. Selection of the recycle feature 

when washing provides for storage of the wash water from the wash cycle 

in a nearby laundry sink or a reservoir in the bottom of the machine, 

for subsequent use as the wash water for the next load. The rinse 

cycles remain unchanged. Since the wash cycle comprises about 45% of 

the total water use per operation, if the wash water is recycled once, 

about 17 gal (64 1) will be saved, if twice, 34 gal (129 1) , and so 

forth. Actual water savings and wastewater flow reductions are highly 

dependent on the user's cycle selection. 

5.2.2.4 Miscellaneous Devices and Systems 

There are a number of additional devices, fixtures, and appliances 

available to help reduce wastewater flow volumes. These are directed 

primarily toward reducing the water flow rate through sink and basin 

faucets.' Table 5-5 presents a summary of several of these additional 

flow reduction devices. Experience with these devices indicates that 

wastewater volume can be reduced by 1 to 2 gpcd (4 to 8 lpcd) when used 

for all sink and basin faucets. 

5.2.3 Wastewater Recycle and Reuse Systems 

Wastewater recycle and reuse systems collect and process the entire 

wastewater flow or the fractions produced by certain activities with 

storage for subsequent reuse. The performance requirements of any 

wastewater recycle system are established by the intended reuse 

activities. To simplify the performance requirements, most recycle 

81

TABLE 5-5 

WASTEWATER FLOW REDUCTION - MISCELLANEOUS DEVICES AND SYSTEMS 


Faucet 

Inserts 

Faucet 

Aerators 

Reduced-Flow 

Faucet 

Fixtures 

Develop- 

ment 

Stageb 

Application 


Device which inserts 4 Compatible with most 

into faucet valve or plumbing. 

supply line and 

restricts flow rate Installation simple. 

with a fixed or 

pressure 

compensating 

orifice. 


Devices attached to 5 Compatible with most 

faucet outlet which plumbing. 

entrain air into 

water flow. Installation simple. 

Varieties: Many. Periodic cleaning of 

aerator screens. 

Similar to 4 Compatible with most 

conventional unit, plumbing. 

but restrict flow 

rate with a fixed or Installation 

pressure identical to 

compensating conventional. 

orifice. 


82


Mixing 

Valves 

Hot Water 

Pipe 

Insulation 


Develop- 

ment 

Stageb 

Application 


Specifically 5 Compatible with most 

designed valve units plumbing. 

which allow flow and 

temperature to be Installation 

set with a single identical to 

control. conventional. 


Hot water piping is 

wrapped with 

insulation to reduce 

heat loss from hot 

water standing in 

pipe between uses. 


4 May be difficult to 

retrofit. 

a No reduction in pollutant mass; insignificant increase in pollutant 

concentration. 

bl = Prototypes developed and under evaluation. 

2 = Development complete; commercial production initiated, but 

distribution restriced. 

3 = Fully developed, limited use, not locally available; mail order 

purchase likely. 

4 = Fully developed, limited use, locally available from plumbing 

supply houses or hardware stores. 

5 = Fully developed, widespread use, locally available from plumbing 

supply houses or hardware stores. 

83

systems process only the wastewaters discharged from bathing, laundry, 

and bathroom sink usage, and restrict the use of the recycled water to 

flushing water-carriage toilets and possibly lawn irrigation. At the 

other extreme, systems are under development that process the entire 

wastewater flow and recycle it as a potable water source. 

The flow sheets proposed for residential recycle systems are numerous 

and varied, and typically employ various combinations of the unit pro- 

cesses described in Chapter 6, complemented by specially designed con- 

trol networks. In Table 5-6, several generic units are characterized 

according to their general recycle flow sheet. 

5.3 Pollutant Mass Reduction 

A second strategy for wastewater modification is directed toward 

decreasing the mass of potential pollutants at the source. This may 

involve the complete elimination of the pollutant mass contributed by a 

given activity or the isolation of the pollutant mass in a concentrated 

wastewater stream. In Table 5-7, several methods for pollutant mass 

reduction are outlined. 

5.3.1 Improved User Habits 

Unnecessary quantities of many pollutants enter the wastewater stream 

when materials, which could be readily disposed of in a solid waste 

form, are added to the wastewater stream. A few examples include 

flushing disposable diapers or sanitary napkins down the toilet, or 

using hot water and detergents to remove quantities of solidified grease 

and food debris from pots and pans to enable their discharge down the 

sink drain. 

5.3.2 Cleaning Agent Selection 

The use of certain cleansing agents can contribute significant quanti- 

ties of pollutants. In particular, cleaning activities, such as 

clotheswashing and dishwashing, can account for over 70% of the phos- 

phorus in residehtial wastewater (Table 4-4). Detergents are readily 

available that contain a low amount of phosphorus compared to other 

detergents. , 

84

TABLE 5-6 

WASTEWATER FLOW REDUCTION - WASTEWATER RECYCLE AND REUSE SYSTEMS 

Total Flow Wastewater Ouality 

Operation and Maintenance Reductionb Impacts 

gpcd % 

Development 

ADDS ication 

Flow Sheet Description stagea Considerations 

Periodic replenishment of 16 36 Sizable removals of 

chemicals, cleaning of pollutants, primarily P. 

filters and storage 

tanks. 

Recycle bath and laundry 2 Requires separate toilet 

for toilet flushing supply and drain line. 



retrofit to multi-story 

building. 

Power use. 

Requries wastewater 

disposal system for 

toilet and kitchen sink 

wastes. 

16 36 Significant removals of 

pollutants. 

Cleaning/replacement of 

filters and other 

treatment and storage 

components. 

Requires separate toilet 

supply line. 

Recycle portion of total 3 

wastewater stream for 

toilet flushing 



retrofit to multi-story 

building. 

Requires disposal system Periodic replenishment of 

for unused recycle water. chemicals.


Devel Opment 

Application Total Flow Wastewater Quality 

Flow Sheet Description stagea Considerations Operation and Maintenance Reductionb Impacts 

wed % 

4 Requires separate toilet Cleaning/replacement of 16 36 Significant removals of 

plumbing network. filters and other pollutants. 

treatment components. 

Utilizes low-flush 

toilets. Residuals disposal. 

Recycle toilet 

wastewaters for flushing 

water carriage toilets 

Requires system for Power use. 

nontoilet wastewaters. 


retrofit. 

application restricted to 

high use on multi-unit 

installations. 

45 1no No wastewater generated 

for onsite disposal. 

l-2 Requires major variance All maintenance by 

from State/local health skilled personnel. 

codes for potable reuse. 

Routine service check. 

Difficult to retrofit. 

Periodic Pump out and 

residuals disposal. 

Recycle total wastewater 

stream for all water uses 

Power use. 

Comprehensive monitoring 

program required. 

a 1 = Prototype developed and under evaluation. 

2 = Development complete; commercial production initiated, but distribution may be restricted. 

3 = Fully developed; limited use, not locally available, mail order purchase likely. 

4 = Fully developed; limited use, locally available from plumbing supply houses and hardware stores. 

5 = Fully developed; widespread use, locally available from plumbing supply houses and hardware stores. 

b Based on the normal waste flow information presented in Table 4-2.

TABLE 5-7 

EXAMPLE POLLUTANT MASS REDUCTION METHODS 

I. Improved User Habits 

II. Cleaning Agent Selection 

III. Elimination of Garbage D isposal App liance 

IV. Segregated Toilet Systems 

A. Non-Water Carriage Toilets 

B. Very Low-Volume Flush Toilets/Holding Tank 

C. Closed Loop Wastewater Recycle Systems 

5.3.3 Elimination of the Garbage Disposal Appliance 

The use of a garbage disposal contributes substantial quantities of BOD5 

and suspended solids to the wastewater load (Table 4-4). As a result, 

it has been.shown that the use of a garbage disposal may increase the 

rate of sludge and scum accumulation and produce a higher failure rate 

for conventional disposal systems under otherwise comparable conditions 

(6). For these reasons, as well as the fact that most waste handled by 

a garbage disposal could be handled as solid wastes, the elimination of 

this appliance is advisable. 

5.3.4 Segregated Toilet Systems 

Several toilet systems can be used to provide for segregation and 

separate handling of human excreta (often referred to as blackwater) 

and, in some cases, garbage wastes. Removal of human excreta from the 

wastewater stream serves to eliminate significant quantities of 

pollutants, 'particularly suspended solids, nitrogen, and pathogenic 

organisms (Table 4-4). 

A number of potential strategies for management of segregated human 

excreta are presented in Figure 5-l. A discussion of the toilet systems 

themselves is presented in the wastewater flow reduction section of this 

chapter, while details regarding the other unit processes in the flow 

sheet may be found in Chapter 6. 

87

Wastewaters generated by fixtures other than toilets are often referred 

to collectively as "graywater.' Characterization studies have demon- 

strated that typical graywater contains appreciable quantities of 

organic matter, suspended solids, phosphorus and grease in a daily flow 

volume of 29 gpcd (110 lpcd) (7)(8)(9)(10)(11)(12)(13)(14~(15) (see 

Table 4-4). Its temperature as it leaves the residence is in the range 

of 31" C, with a pH slightly on the alkaline side. The organic materi- 

als in graywater appear to degrade at a rate not significantly different 

from those in combined residential wastewater (15). Microbiological 

studies have demonstrated that significant concentrations of indicator 

organisms as total and fecal coliforms are typically found in graywater 

(7)(11)(12)(13)(14)(15). One should assume, therefore, that graywater 

harbors pathogens. 

Although residential graywater does contain pollutants and must be prop- 

erly managed, graywater may be simpler to manage than total residential 

wastewater due to a reduced flow volume. While diverse strategies have 

been proposed for graywater management (Figure 5-21, rigorous field 

evaluations have not been conducted in most cases. Until further field 

data become available, it is recommended that graywater treatment and 

disposal/reuse systems be designed as for typical residential wastewater 

(as described in Chapter 6). Design allowances should be made only for 

the reductions in flow volume, as compared to typical residential 

wastewater. 

5.4 Onsite Containment - Holding Tanks 

Wastewaters may be contained on site using holding tanks, and then 

transported off site for subsequent treatment and disposal. In many 

respects, the design, installation, and operation of a holding tank is 

similar to that for a septic tank (as described in Chapter 6). Several 

additional considerations do exist, as indicated in Table 5-8. A dis- 

cussion regarding the disposal of the pumpage from holding tanks is pre- 

sented in Chapter 9 of this manual. 

5.5 Reliability 

An important aspect of wastewater modification concerns the reliability 

of a given method to yield a projected modification at a specific 

dwelling or establishment over the long term. This is of particular 

importance when designing an onsite wastewater disposal system based on 

modified wastewater characteristics. 

88

FIGURE 5-l 

EXAMPLE STRATEGIES FOR MANAGEMENT OF SEGREGATED HUMAN WASTES 

1 Privy 1 1 Compo; Toilet 1 

+I 

Disinfection 

Very Low-Volume 

I Flush Toilet 

FIGURE 5-2 

el Disinfection 

EXAMPLE STRATEGIES FOR MANAGEMENT OF RESIDENTIAL GRAYWATER 

Soil Absorption 

Alternatives 

t 

1 Sedimentation 

89 

1 

1 

Further 


I

Sizing 

Item 

Discharge 

Alarm System 

Accessibility 

Flotation 

cost 

TABLE 5-8 

ADDITIONAL CONSIDERATIONS IN THE DESIGN, 

INSTALLATION, AND OPERATION OF HOLDING TANKS 

Consideration 

Liquid holding capacity >7 days 

wastewater flow generation. Minimum 

capacity = 1,000 gallons. 

There should be no discharge. 

High water alarm positioned to allow at 

least 3 days storage after activation. 

Frequent pumping is likely; therefore 

holding tank(s) must be readily accessible 

to pumping vehicle. 

Large tanks may be subject to severe 

flotation forces in high groundwater areas 

when pumped. 

Frequent pumping and residuals disposal 

results in very high operating costs. 

Assessing the reliability of wastewater modification methods is a com- 

plex task which includes considerations of a technological, sociologi- 

cal, economic, and institutional nature. Major factors affecting 

reliability include: 

1. The actual wastewater characteristics prior to modification 

compared to the average. 

2. User awareness and influence on method performance. 

3. Installation. 

4. Method performance. 

5. User circumvention or removal. 

90

In most situations, projections of the impact of a wastewater modifica- 

tion method must necessarily be made, assuming the wastewater charac- 

teristics prior to modification are reasonably typical. If the actual 

wastewater characteristics deviate significantly from that of the aver- 

age, a projected modification may be inaccurate. 

The prospective user should be fully aware of the characteristics of a 

method considered for use prior to its application. Users who become 

aware of the characteristics of a method only after it has been put into 

use are more likely to be dissatisfied and attempt to circumvent or 

otherwise alter the method and negate the wastewater modification 

expected. 

In general, passive wastewater modification methods or devices not sig- 

nificantly affected by user habits tend to be more reliable than those 

which are subject to user habits and require a preconceived active role 

by the users. For example, a low-flush toilet is a passive device, 

while a flow-reducing shower head is an active one. 

Installation of any devices or systems should be made by qualified 

personnel. In many situations, a post-installation inspection is 

recommended to ensure proper functioning of the device or system. 

Method performance is extremely important in assessing the reliability 

of the projected modification. Accurate performance data are necessary 

to estimate the magnitude of the reduction, and to predict the likeli- 

hood that the method will receive long-term user acceptance. Accurate 

performance data can only be obtained through the results of field test- 

ing and evaluations. Since many methods and system components are pres- 

ently in various stages of development, only preliminary or projected 

operation and performance data may be available. This preliminary or 

projected data should be considered cautiously. 

The continued employment of a wastewater modification method can be 

encouraged through several management actions. First, the user(s) 

should be made fully aware of the potential consequences if they should 

discontinue employing the modification method (e.g., system failure, 

water pollution, rejuvenation costs, etc.). Also, the appropriate man- 

agement authority can approve only those methods whose characteristics 

and merits indicate a potential for long-term user acceptance. Further, 

installation of a device or system can be made in such a manner as to 

discourage disconnection or replacement. Finally, periodic inspections 

by a local inspector within the framework of a sanitary district or the 

like may serve to identify plumbing alterations; corrective orders could 

then be issued. 

91

To help ensure that a projected modification will actually be realized 

at a given site, efforts can be expended to accomplish the following 

tasks:- 

1. 

2. 

3. 

4. 

5. 

Confirm that the .actual wastewater characteristics prior to 

modification are typical. 

Make the prospective user(s) of the modification method fully 

aware of the characteristics of the method, including its oper- 

ation, maintenance, and costs. 

Determine if the projected performance of a given method has 

been confirmed through actual field evaluations. 

Ensure that any devices or systems are installed properly by 

competent personnel. 

Prevent user removal or circumvention of devices, systems, or 

methods. 

5.6 Impacts on Onsite Treatment and Disposal Practices 

5.6.1 Modified Wastewater Characteristics 

Reducing the household wastewater flow volume without reducing the mass 

of pollutants contributed will increase the concentration of pollutants 

in the wastewater stream. The increase in concentrations will likely be 

insignificant for most flow reduction devices .with the exception of 

those producing flow reductions of 20% or more. The increase in pollu- 

tant concentrations in any case may be estimated utilizing Figure 5-3. 

5.6.2 Wastewater Treatment and Disposal Practices 

In Table 5-9, a brief summary of several potential impacts that 

wastewater modification may have on onsite disposal practices is 

presented. It must be emphasized that the benefits derived from 

wastewater modification are potentially significant. Wastewater 

modification methods, particularly wastewater flow reduction, should be 

considered an integral part of any onsite wastewater disposal system. 

92

FIGURE 5-3 

FLOW REDUCTION EFFECTS ON POLLUTANT CONCENTRATIONS 

80- 

A 

60 - 

Wastewater Flow Reduction, percent of total daily flow 

(Assumes Pollutant ‘Contributions the Same 

Under the Reduced Flow Volume) 

93

TABLE 5-9 

POTENTIAL IMPACTS OF WASTEWATER MODIFICATION 

ON ONSITE DISPOSAL PRACTICES 

Modification Practice 

Disposal System Fl ow Pollutant 

Type Reduction Reduction 

All Disposal X X 

Surface Disposal 

Evapotranspiration X 

Onsite Containment X 

X 

X 

X 

Potential Impact 

May extend service life of 

functioning system, but 

cannot quantify. 

Reduce water resource 

contamination. 

Simplify site constraints. 

Reduce frequency of septic 

tank pumping. 

Reduce sizing of 

infiltrative area. 

Remedy hydraulically 

overloaded system. 

X Reduce component 0 and M 

costs. 

X Reduce sizing of components. 

X Eliminate need for certain 

components (e.g., nitrogen 

removal 1. 

94 

Remedy hydraulically 


Remedy a hydraulically 


Reduce sizing of ET area. 

Reduce frequency of pumping. 

Reduce sizing of containment 

basin.


1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

Wagner, E. G., and J. N. Lanoix. Excreta Disposal for Rural Areas 

and Small Communities. WHO Monograph 39, World Health Organiza- 

tion, Geneva, Switzerland, 1958. 187 pp. 

Stoner, C. H. Goodbye to the Flush Toilet. Rodale Press, Emmaus, 

Pennsylvania, 1977. 

Rybczynski, W., and A. Ortega. Stop the Five Gallon Flush. Mini- 

mum Coast Housing Group, School of Architecture, McGill University, 

Montreal, Canada, 1975. 

Van Der Ryn, S. Compost Privy. Technical Bulletin No. 1, Faral- 

lones Institute, Occidental, California, 1974. 

Rybezynski, W., C. Polprasert, and M. McGarry. Low-Cost Technical 

Options for Sanitation. Report IDRC-102e, International Develop- 

ment Research Center, Ottawa, Canada, 1978. 

Bendixen, T. W., R. E. Thomas, A. A. McMahan, and J. B. Coulter. 

Effect of Food Waste Grinders on Septic Tank Systems. Robert A. 

Taft Sanitary Engineering Center, Cincinnati, Ohio, 1961. 119 pp. 

Siegrist, R. L., M. Witt, and W. C. Boyle. Characteristics of 

Rural Housing Wastewater. J. Environ. Eng. Div., Am. Sot. Civil 

Ens, 102:553-548, 1976. 

Laak, R. Relative Pollution Strengths of Undiluted Waste Materials 

Discharged in Households and the Dilution of Waters Used for Each. 

Manual of Grey Water Treatment Practice - Part II. Monogram Indus- 

tries, Inc., Santa Monica, California, 1975. 

Bennett, E. R., and E. K. Linstedt. Individual Home Wastewater 

Characterization and Treatment. Completion Report Series No. 66, 

Environmental Resources Center, Colorado State University, Fort 

Collins, 1975. 145 pp. 

Ligman, K., N. Hutzler, and W. E. Boyle. Household Wastewater 

Characterization. 3. Environ. Eng. Div., Am. Sot. Civil Eng., 

150:201-213, 1974. 

Olsson, E., L. Karlgren, and V. Tullander. Household Wastewater. 

National Swedish Institute for Building Research, Stockholm, Swe- 

den, 1968. 

Hypes, W. D., C. E. Batten, and J. R. Wilkins. The Chemical/ 

Physical and Microbiological Characteristics of Bath and Laundry 

Wastewaters. NASA TN D-7566, Langley Research Center, Langley 

Center, Virginia, 1974. 31 pp. 

95

13. Small Scale Waste Management Project, University of Wisconsin, 

Madison. Management of Small Waste Flows. EPA-600/2-78-173, NTIS 


14. Brandes, M. Characteristics of Effluents from Separate Septic 

Tanks Treating Grey and Black Waters From the Same House. J. Water 


15. Siegrist, R. L. Management of Residential Grey Water. Proceedings 

of the Second Pacific Northwest Onsite Wastwater Disposal Short 

Course, University of Washington, Seattle, March 1978. 

96


CHAPTER 6 

ONSITE TREATMENT METHODS 

This chapter presents information on the component of an onsite system 

that provides "treatment" of the wastewater, as opposed to its 

"disposal ' (disposal options for treated wastewater are covered in 

Chapter 7). Treatment options included in this discussion are: 

1. Septic tanks 

2. Intermittent sand filters 

3. Aerobic treatment units 

4. Disinfection units 

5. Nutrient removal systems 

6. Wastewater segregation and recycle systems 

Detailed design, O&M, performance, and construction data are provided 

for the first four components above. A more general description of 

nutrient removal is provided as these systems are not yet in general 

use, and often involve in-house changes in product use and plumbing. A 

brief mention of wastewater segregation and recycle options is included, 

since these also function as treatment options. 

Options providing a combined treatment/disposal function, i.e., soil 

absorption systems, are discussed in Chapter 7. 

6.1.1 Purpose 

The purpose of the treatment component is to transform the raw household 

wastewater into an effluent suited to the disposal component, such that 

the wastewater can be disposed of in conformance with public health and 

environmental regulations. For example, in a subsurface soil absorption 

system, the pretreatment unit (e.g., septic tank) should remove nearly 

all settleable solids and floatable grease and scum so that a reasonably 

clear liquid is discharged into the soil absorption field. This allows 

the field to operate more efficiently. Likewise, for a surface 

discharge system, the treatment unit should produce an effluent that 

will meet applicable surface discharge standards. 

97

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pinb!L ayq 41 CM tun3s pue a6pn 1s 40 6u~x~tu was ‘~uaiQJedwo3 3s~ i4 aqt) UI 

2uaAaJd 02 pap!AoJd SC Leas JadoJd e 41 aDe4Jns punoJ6 aya 01 pua~~xa ue3 

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901

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801

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l adkd aa tqno pue aa tuc aq? 02 pue aaaJwo3 02 qloq 

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8) *ui p 03 & 40 ssauy3kqa e aAeq s tteM aql wab4 w ui uwet tww 

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'(E) UOkSOJJO3 03 

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l te!Jnq Jaq4e 3.L JaAo sahoui KJau iq3euI LAeaq uaqM 

saJnpa3oJd uo!aetteqsuI 9.2.9 

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605

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l La klua’)od 

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l stua LqoJd ano-duuld ale!A 

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l JaJeM qa)M 6ui ~1~4 Kq SSaU$q6&GQeM ~04 pac)saq 

aq iww yule3 w ~uowLLwu4 Jaw l paJiedaJ aq pLnoqs 

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l sassaJas paziLesoL anpun Z)UaAaJd 03 sy30~ 

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l s L La pue saal Jo4 lsaq aJe uoJ L qse3 pue ‘3 !aseLd ‘aLi 

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luels IsaJ-p i3e JO sse L6Jaq )j ‘S Le kJaZ$elU 4OOJd-UO bSOJJO3 

pue aLqeJnp 40 apw aq p Lnoqs sMoqLa pue ‘saaa ‘saL44ea •~ 

a3ueuaw~~ pue uo!aeJado L’Z.9 

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p Lnoqs yule3 D!Jse Ld JO 'sse L6Jaqk4 ‘aqa~3uo3 pauley,Jleur pue pau6ksap 

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01 sJearC z KJaAa ueqa aJow ou 40 sLeAJa>uk ae paqDadsuk aq pLnoqs syuel

l paq3eaJ aJe suok7cpuo3 asay aJo4aq aseaJ3ap 01 

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phosphorus are normally less than 25%. The removal of indicator bac- 

teria in onsite extended aeration processes is highly variable and not 

well documented. Reported values of fecal coliforms appear to be about 

2 orders of magnitude lower in extended aeration effluents than in 

septic tank effluents (2). 

6.4.2.4 Design 

A discussion of some of the important features of onsite extended aera- 

tion package plants in light of current operational experience is pre- 

sented below. 

a. Configuration 

Most extended aeration package plants designed for individual home ap- 

plication range in capacity from 600 to 1,500 gal (2,270 to 5,680 11, 

which includes the aeration compartment, settling chamber, and in some 

units, a pretreatment compartment. Based upon average flows from house- 

holds, this volume will provide total hydraulic retention times of 

several days. 

b. Pretreatment 

Some aerobic units provide a pretreatment step to remove gross solids 

(grease, trash, garbage grindings, etc.). Pretreatment devices include 

trash traps, septic tanks, comminutors, and aerated surge chambers. The 

use of a trash trap or septic tank preceding the extended aeration pro- 

cess reduces problems with floating debris in the final clarifier, clog- 

ging of flow lines, and plugging of pumps. 

c. Flow Mode 

Aerobic package plants may be designed as continuous flow or batch flow 

systems. The simplest continuous flow units provide no flow equaliza- 

tion and depend upon aeration tank volume and/or baffles to reduce the 

impact of hydraulic surges. Some units employ more sophisticated flow 

dampening devices, including air lift or float-controlled mechanical 

pumps to transfer the wastewater from aeration tank to clarifier. Still 

other units provide multiple-chambered tanks to attenuate flow. The 

batch (fill and draw) flow system eliminates the problem of hydraulic 

variation. This unit collects and treats the wastewater over a period 

of time (usually one day), then discharges the settled effluent by pump- 

ing at the end of the cycle. 

147

d. Method of Aeration 

Oxygen is transferred to the mixed liquor by means of diffused air, 

sparged turbine, or surface entrainment devices. When diffused air sys- 

tems are employed, low head blowers or compressors are used to force the 

air through the diffusers placed on the bottom of the tank. The sparged 

turbine employs both a diffused air source and external mixing, usually 

by means of a submerged flat-bladed turbine. The sparged turbine is 

more complex than the simple diffused air system. There are a variety 

of mechanical aeration devices employed in package plants to aerate and 

mix the wastewater. Air is entrained and circulated within the mixed 

liquor through violent agitation from mixing or pumping action. 

Oxygen transfer efficiencies for these small package plants are normally 

low (0.2 to 1.0 lb 0 /hp hr) (3.4 to 16.9 kg 02/MJ) as compared with 

large-scale systems ii ue primarily to the high power inputs to the 

smaller units (constrained by minimm motor sizes for these relatively 

small aeration tanks) (2). Normally, there is sufficient oxygen trans- 

ferred to produce high oxygen levels. In an attempt to reduce power 

requirements or to enhance nitrogen removal, some units employ cycled 

aeration periods. Care must be taken to avoid the development of poor 

settling biomass when cycled aeration is used. 

Mixing of the aeration tank contents is also an important consideration 

in the design of oxygen transfer devices. Rule of thumb reqvrements 

for mixing i3 aeration tanks range from 0.5 to 1 hp/l,OOO ft (13 to 

26 kw/l,OOO m ) depending upon reactor geometry. Commercially available 

package units Q re reported to deliver mixing inputs rangCng from 0.2 to 

3 hp/l,OOO ft (5 to 79 kw/l,OOO m3) (2). Deposition problems may 

develop in those units with the lower mixing intensities. 

e. Biomass Separation 

The clarifier is critical to the successful performance of the extended 

aeration process. A majority of the commercially available package 

plants provide simple gravity separation. Weir and baffle designs have 

not been given much attention in package units. Weir lengths Qjf at 

least 12 in. (30 cm) are preferred (10,000 gpd/ft at 7 gpm) (127 m /d/m 

at 0.4 l/set) and sludge deflection baffles should be included as a part 

of the outlet design. The use of gas deflection barriers is a simple 

way to keep floating solids away from the weir area. 

Upflow clarifier devices have also been employed to improve separation.' 

Hydraulic surges must be avoided in these systems. Filtration devices 

148

have also been employed in some units. While filters may produce highquality 

effluent, they are very susceptible to both internal and 

external clogging. The behavior of clarifiers is dependent upon biomass 

settling properties, 

D5sign2peak hydraulic 

solids loading 

overflow rates 

rate, and hydraulic overflow ra es. 

should be less than 800 gpd ft 5 (32 

m /d/m 1; $nd at averag flo design values normally range from 200 to 

400 gpd/ft (J to 16 m'/d,$rn'l Solids loading rates are usually less 

than $0 lb/ft /d ($45 kg/m /dl'based upon average flow and less than 50 

lb/ft /d (242 kg/m /d) based upon peak flows. 

f. Biomass Return 

Once separated from the treated wastewater, the biomass must be returned 

to the aeration tank or be wasted. Air lift pumps, draft tubes working 

off the aerator, and gravity return methods are normally used. Batch 

units and plants that employ filters do not require sludge return. 

Rapid removal of solids from the clarifier is desirable to avoid deni- 

trification and subsequent floatation of solids. Positive sludge return 

should be employed in package plants since the use of gravity return 

systems has generally proved ineffective (2)(20). 

Removal of floating solids from clarifiers has normally been ignored in 

most onsite package plant designs. Since this material results in 

serious deterioration of the effluent, efforts should be made to provide 

for positive removal of this residue. Reliance on the owner to remove 

floating scum is unrealistic. 

!I* Biomass Wasting 

Most onsite package plants do not provide for routine wasting of solids 

from the unit. Some systems, however, do employ an additional chamber 

for aerobic digestion of wasted sludge. Wasting is normally a manual 

operation whereby the operator checks mixed liquor solids and wasted 

sludge when mixed liquor concentrations exceed a selected value. In 

general, wasting should be provided once every 8 to 12 months (2)(35). 

h. Controls and Alarms 

Most aerobic units are supplied with some type of alarm and control sys- 

tem to detect mechanical breakdown and to control the operation of elec- 

trical components. They do not normally include devices to detect 

effluent quality or biomass deterioration. Since the control systems 

149

contain electrical components, they are subject to corrosion. All elec- 

trical components should be waterproofed and regularly serviced to 

ensure their continued operation. 

6.4.2.5 Additional Construction Features 

Typical onsite extended aeration package plants are constructed of 

noncorrosive materials, including reinforced plastics and fiberglass, 

coated steel, and reinforced concrete. The unit may be buried provided 

that there is easy access to all mechanical parts and electrical control 

systems, as well as appurtenances requiring maintenance such as weirs, 

air lift pump lines, etc. Units may also be installed above ground, but 

should be properly housed to protect against severe climatic conditions. 

Installation of the units should be in accordance with specifications of 

the manufacturers. 

Appurtenances for the plant should be constructed of corrosion-free 

materials including polyethylene plastics. Air diffuser support legs 

are normally constructed from galvanized iron or equivalent. 

Large-diameter air lift units should be employed to avoid clogging 

problems. Mechanical units should be properly waterproofed and/or 

housed from the elements. 

Since blowers, pumps, and other prime movers are abused by severe envi- 

ronment, receive little attention, and are often subject to continuous 

operation, they should be designed for heavy duty use. They should be 

easily accessible for routine maintenance and tied into an effective 

alarm system. 

6.4.2.6 Operation and Maintenance 

a. General Plant Operation 

Typical operating parameters for onsite extended aeration systems are 

presented in Table 6-14. The activated sludge process can be operated 

by controlling only a few parameters - the aeration tank dissolved oxy- 

gen, the return sludge rate, and the sludge wasting rate. For onsite 

package plants, these control techniques are normally fixed by mechani- 

cal limitations so that very little operational control is required. 

Dissolved oxygen is normally high and cannot be practically controlled 

except by "on or off" operation. Experimentation with the process may 

dictate a desirable cycling arrangement employing a simple time clock 

150

MLSS, mg/l 

TABLE 6-14 

TYPICAL OPERATING PARAMETERS FOR ONSITE EXTENDED AERATION SYSTEMS 

F/M, lb BOD/d/lb MLSS 

Parametera Average Maximum 

Solids Retention Time, days 

Hydraulic Retention Time, days 

Dissolved Oxygen, mg/l 

Mixing, hp/l,OOO ft3 

Clarifier Overflow Rate, gpd/ft2 

Clarifier Solids Loading, lb/d/ftz 

Clarifier Weir Loading, gpd/ftz 

Sludge Wasting, months 

a Pretreatment: Trash trap or septic tank. 

Sludge Return and Scum Removal: Positive. 

151 

2,000-6,000 8,000 

0.05 - 0.1 

20-100 

2-5 

>2.0 

0.5-1.0 

200-400 800 

20-30 50 

10,000-30,000 30,000 

8-12

control that results in power savings and may also achieve some nitrogen 

removal (Section 6.6). 

The return sludge rate is normally fixed by pumping capacity and pipe 

arrangements. Return sludge pumping rates often range from 50 to 200% 

of forward flow. They should be high enough to reduce sludge retention 

times in the clarifier to a minimum (less than 1 hr), yet low enough to 

discourage pumping of excessive amounts of water with the sludge. Time 

clock controls may be used to regulate return pumping. 

Sludge wasting is manually accomplished in most package plants. Through 

experience, the operator knows when mixed liquor solids concentrations 

become excessive, resulting in excessive clarifier loading. Usually 8- 

to 12-month intervals between wasting is satisfactory, but this varies 

with plant design and wastewater characteristic. Wasting is normally 

accomplished by pumping mixed liquor directly from the aeration tank. 

Wasting of approximately 75% of the aeration tank volume is usually 

satisfactory. Wasted sludge must be handled properly (see Chapter 9). 

b. Start-Up 

Prior to actual start-up, a dry checkout should be performed to insure 

proper installation. Seeding of the plant with bacterial cultures is 

not required as they will develop within a 6- to 12-week period. Ini- 

tially, large amounts of white foam may develop, but will subside as 

mixed liquor solids increase. During start-up, it is advisable to re- 

turn sludge at a high rate. Intensive surveillance. by qualified 

maintenance personnel is desirable during the first month of start-up. 

c. Routine Operation and Maintenance 

Table 6-15 itemizes suggested routine maintenance performance for onsite 

extended aeration package plants. The process is labor-intensive and 

requires semi-skilled personnel. Based upon field experience with these 

units, 12 to 48 man-hr per yr plus analytical services are required to 

insure reasonable performance. Power requirements are variable, but 

range between 2.5 to 10 kWh/day. 

d. Operational Problems 

Table 6-16 outlines an abbreviated listing of operational problems and 

suggested remedies for them. A detailed discussion of these problems 

152

I tern 

Aeration Tank 

Aeration System 

Diffused air 

Mechanical 

Clarifier 

Trash Trap 

Controls 

Sludge Wasting 

Analytical 

TABLE 6-15 

SUGGESTED MAINTENANCE FOR ONSITE 

EXTENDED AERATION PACKAGE PLANTSa 

Suggested Maintenance 

Check for foaming and uneven air distribution. 

Check air filters, seals, oil level, back pressure; 

perform manufacturer's required maintenance. 

Check for vibration and overheating; check oil 

level, seals; perform manufacturer's required 

maintenance. 

Check for floating scum; check effluent appearance; 

clean weirs; hose down sidewalls and appurtenance; 

check sludge return flow rate and adjust time 

sequence if required; locate sludge blanket; 

service mechanical equipment as required by 

manufacturer. 

Check for accumualted solids; hose down sidewalls. 

Check out functions of all controls and alarms; 

check electrical control box. 

Pump waste solids as required. 

Measure aeration tank grab sample for DO, MLSS, pH, 

settleability, temperature; measure final effluent 

composite sample for BOD, SS, pH (N and P if 

required). 

a Maintenance activities should be performed about once per month. 

153

TABLE 6-16 

OPERATIONAL PROBLEMS--EXTENDED AERATION 

Observation 

Excessive local 

turbulence in 

aeration tank 

White thick billowy 

foam on aeration 

tank 

Thick scummy dark 

tan foam on 

aeration tank 

Dark brown/black foam 

and mixed liquor in 

aeration tank 

Billowing sludge 

washout in 

clarifier 

Clumps of rising 

sludge in clarifier 

Fine dispersed floe 

over weir, turbid 

effluent 

Cause 

Diffuser plugging 

Pipe breakage 

Excessive aeration 

Insufficient MLSS 

High MLSS 

Anaerobic conditions 

Aerator failure 

Hydraulic or solids 

overload 

Bulking sludge 

Denitrification 

Septic conditions 

in clarifier 

Turbulence in 

aeration tank 

Sludge age too 

high 

154 

PACKAGE PLANTS 

Remedv 

Remove and clean 

Replace as required 

Throttle blower 

Avoid wasting solids 

Waste solids 

Check aeration system, 

aeration tank D.O. 

Waste sludge; check 

flow to unit 

See reference (37) 

Increase sludge return 

rate to decrease 

sludge retention time 

in clarifier 

Increase return rate 

Reduce power input 

Waste sludge

for larger, centralized systems can be found in the "Manual of Practice 

- Operation of Wastewater Treatment Plants" (36) and "Process Control 

Manual for Aerobic Biological Wastewater Treatment Facilities" (37). 

Major mechanical maintenance problems for onsite treatment units are 

with blower or mechanical aerator failure, pump and pipe clogging, 

electrical motor failure, corrosion and/or failure of controls, and 

electrical malfunctions (35). Careful attention to a maintenance 

schedule will reduce these problems to a minimum, and will also 

alleviate operational problems due to the biological process upset. 

Emphasis should be placed on adequate maintenance checks during the 

first 2 or 3 months of operation. 

6.4.2.7 Considerations for Multi-Home Application 

The extended aeration process may be well suited for multiple-home or 

commercial applications. The same requirements listed for single onsite 

systems generally apply to the larger scale systems (20)(36)(37)(38). 

However, larger package plant systems may be more complex and require a 

greater degree of operator attention. 

6.4.3 Fixed Film Systems 

6.4.3.1 Description 

Fixed film systems employ an inert media to which microorganisms may 

become attached. The wastewater comes in contact with this fixed film 

of microorganisms either by pumping the water past the media or by mov- 

ing the media past the wastewater to be treated. Oxygen may be supplied 

by natural ventilation or by mechanical or diffused aeration within the 

wastewater. Fixed film reactors are normally constructed as packed tow- 

ers or as rotating plates. Figure 6-12 depicts three types of onsite 

fixed film systems - the trickling filter (gravity flow of wastewater 

downward), the upflow filter (wastewater pumped upward through the 

media), and the rotating biological contractor. 

The trickling filter has been used to treat wastewater for many years. 

Modern filters today consist of towers of media constructed from a vari- 

ety of plastics, stone, or redwood laths into a number of shapes (honey- 

comb blocks, rings, cylinders, etc.). Wastewater is distributed over 

the surface of the media and collected at the bottom through an undrain 

system. Oxygen is normally transferred by natural drafting, although 

some units employ blowers. Treated effluent is settled prior to being 

discharged or partially recycled back through the filter. 

155

I 

TRICKLING FILTFR 

FIGURE 6-12 

EXAMPLES OF FIXED FILM PACKAGE PLANT CONFIGURATIONS 

UPFLOW FILTER 

lnfluent,Distributor 

Efflu ent II 

ROTATING 

BIOLOGICAL CONTACTOR 

Pump 

;;:,=$ip -Effluent to Clarifier or Septic Tank 

4 

156 

I 

lent 

V Septic 

2 Tank

In an upflow filter, wastewater flows through the media and is 

subsequently collected at an overflow weir. Oxygen may be transferred 

to the biomass by means of diffusers located at the bottom of the tower 

or by surface entrainment devices at the top. One of the commercially 

available units of this type (built primarily for shipboard use) does 

not require effluent sedimentation prior to discharge (Figure 6-12). 

Circulation of wastewater through this particular unit promotes the 

shear of biomass from the media and subsequent carriage to the tank 

bottom. 

The rotating biological contactor (RBC) employs a series of rotating 

discs mounted on a horizontal shaft. The partially submerged discs 

rotate at rates of 1 to 2 rpm through the wastewater. Oxygen is 

transferred to the biomass as the disc rotates from the air to the water 

phase. Recirculation of effluent is not normally practiced. 

6.4.3.2 Applicability 

There has been little long-term field experience with onsite fixed film 

systems. Generally, they are less complex than extended aeration sys- 

tems and should require less attention; if designed properly they should 

produce an effluent of equivalent quality. 

There are no significant physical site constraints that should limit 

their application, although local codes may require certain set-back 

distances. The process is more temperature sensitive than extended 

aeration and should be insulated as required. Rotating biological 

contactors should also be protected from sunlight to avoid excessive 

growth of algae which may overgrow the plate surfaces. 

6.4.3.3 Factors Affecting Performance 

Limited data are currently available on long-term performance of onsite 

fixed film systems. Detailed description of process variables that 

affect fixed film process perfomrance appear in the "Manual of Practice 

for Wastewater Treatment Plant Design" (20). Low loaded filters should 

also achieve substantial nitrification, as well as good BOD and SS 

reductions. 


Onsite fixed film systems include a variety of proprietary devices. 

Design guidelines are, therefore, difficult to prescribe. Table 6-17 

157

presents suggested design ranges for two generic fixed film systems, the 

RBC and the fixed media processes. 

TABLE 6-17 

TYPICAL OPERATING PARAMETERS FOR ONSITE FIXED FILM SYSTEMS 

Parametera Fixed Media RBC 

Hydraulic Loading, gpd/ft2 25-100 0.75-1.0 

Organic Loading, lb BOD/d/lOOO ft8 5-20 1.0-1.5 

Dissolved Oxygen, mg/l >2.0 >2.0 

Overflow Rate, gpd/ft2 600-800 600-800 

Weir Loading, gpd/ft2 10,000-20,000 10,000-20,000 

Sludge Wasting, months 8-12 8-12 

a Pretreatment: Settling or screening. 

Recirculation: Not required. 

All fixed film systems should be preceded by settling and/or screening 

to remove materials that will otherwise cause process malfunction. 

Hydraulic loadings are normally constrained by biological reaction rates 

and mass transfer. 

Organic loading is primarily dictated by oxygen transfer within the bio- 

logical film. Excessive organic loads may cause anaerobic conditions 

resulting in odor and poor performance. Dissolved oxygen in the liquid 

should be at least 2 mg/l. Recirculation is not normally practiced in 

package fixed film systems since it adds to the degree of complexity and 

is energy and maintenance intensive. However, recirculation may be 

desirable in certain applications where minimum wetting rates are 

required for optimal performance. 

The production of biomass on fixed film systems is similar to that for 

extended aeration. Very often, accumulated sludge is directed back to 

the septic tank for storage and partial digestion. 

158

6.4.3.5 Construction Features 

Very few commercially produced fixed film systems are currently avail- 

able for onsite application. Figure 6-12 illustrates several flow ar- 

rangements that have been employed. Specific construction details are 

dependent on system characteristics. In general, synthetic packing or 

attachment media are preferred over naturally occurring materials be- 

cause they are lighter, more durable, and provide better void volume - 

surface area characteristics. All fixed film systems should be covered 

and insulated as required against severe weather. Units may be in- 

stalled at or below grade depending upon site topography and other adja- 

cent treatment processes. Access to all moving parts and controls is 

required, and proper venting of the unit is paramount, especially if 

natural ventilation is being used to supply oxygen. Underdrains, where 

required, should be accessible and designed to provide sufficient air 

space during maximum hydraulic loads. Clarification equipment should 

include positive sludge and scum handling. All pumps, blowers, and 

aeration devices, if required, should be rugged, corrosion-resistant, 

and built for continuous duty. 


a. General Process Operation 

Fixed film systems for onsite application normally require very minimal 

operation. Rotating biological contactors are installed at fixed rota- 

tional speed and submergence. Flow to these units is normally fixed 

through the use of an integrated pumping system. Sludge wasting is nor- 

mally controlled by a timer setting. Through experience, the operator 

may determine when clarifier sludge should be discharged in order to 

avoid sludge flotation (denitrification) or excessive build-up. 

Where aeration is provided, it is normally designed for continuous duty. 

On-off cycling of aeration equipment may be practiced for energy conser- 

vation if shown not to cause a deterioration of effluent quality. 

b. Routine Operation and Maintenance 

Table 6-18 itemizes suggested routine maintenance performance for onsite 

fixed film systems. The process is less labor-intensive than extended 

aeration systems and requires semi-skilled personnel. Based upon very 

limited field experience with these units, 8 to 12 man-hr per yr plus 

159

Item 

Media Tank 

Aeration System 

RBC Unit 

Clarifier 

Trash Trap 

Controls 

Analytical 

TABLE 6-18 

SUGGESTED MAINTENANCE FOR ONSITE 

FIXED FILM PACKAGE PLANTSa 

Suggested Maintenance 

Check media for debris accumulation, ponding, 

and excessive biomass - clean as required; 

check underdrains - clean as required; hose 

down sidewalls and appurtenances; check 

effluent distribution and pumping - clean as 

required. 

See Table 6-15 

Lubricate motors and bearings; replace seals as 

required by manufacturer. 




Measure final effluent composite sample for 

BOD, SS, pH (N and P if required). 

a Maintenance activities should be performed about once per month. 

160

analytical services are required to ensure adequate performance. Power 

requirements depend upon the device employed, but may range from 1 to 

4 kWh/day. 

c. Operational Problems 

Table 6-19 outlines an abbreviated list of potential operational 

problems and suggested remedies for onsite fixed film systems. A 

detailed discussion of these may be found in the "Manual of Practice - 

Operation of Wastewater Treatment Plants" (36) and "Process Control 

Manual for Aerobic Biological Wastewater Treatment Facilities" (37). 

6.4.3.7 Considerations for Multi-Home Applications 

Fixed film systems may be well suited for multiple-home or commercial 

applications. The same requirements for single-home onsite systems 

apply to the large-scale systems (20)(29)(37)(38). However, larger 

systems may be more complex and require a greater degree of operator 

attention. 

6.5 Disinfection 

6.5.1 Introduction 

Disinfection of wastewaters is employed to destroy pathogenic organisms 

in the wastewater stream. Since disposal of wastewater to surface water 

may result in potential contacts between individuals and the wastewater, 

disinfection processes to reduce the risk of infection should be 

considered. 

There are a number of important waterborne pathogens found in the United 

States (39)(40)(41)(42). Within this group of pathogens, the protozoan 

cyst is generally most resistant to disinfection processes, followed by 

the virus and, the vegetative bacteria (43). The design of the disin- 

fection process must necessarily provide effective control of the most 

resistant pathogen likely to be present in the wastewater treated. Up- 

stream processes may effectively reduce some of these pathogens, but 

data are scant on the magnitude of this reduction for most pathogens. 

Currently, the effectiveness of disinfection is measured by the use of 

indicator bacteria (total or fecal coliform) or disinfectant residual 

where applicable. Unfortunately, neither method guarantees complete 

destruction of the pathogen, and conservative values are often selected 

to hedge against this risk. 

161

Observation 

Filter Ponding 

Filter Flies 

Odors 

Freezing 

Excessive Biomass 

Accumulation 

Poor Clarification 

TABLE 6-19 

OPERATIONAL PROBLEMS--FIXED FILM PACKAGE PLANTS 

Cause 

Media too fine 

Organic overload 

Debris 

Poor wastewater 

distribution 

Poor ventilation/ 

aeration 

Improper 

insultation 

Organic overload 

Low pH; anaerobic 

conditions 


in clarifier 

Hydraulic o.verload 

162 

Replace media 

Remedy 

Flush surface with high pressure 

stream; increase recycle rate; 

dose with chlorine (lo-20 mg/l 

for 4 hours) 

Remove debris; provide 

pretreatment 

Provide complete wetting of 

media; increase recycle rate; 

chlorinate (5 mg/l for 6 hours 

at 1 to 2 week intervals) 

Check underdrains; maintain 

aeration equipment, if 

employed; insure adequate 

ventilation; increase recycle 

Check and provide sufficient 

insulation 

Increase recycle; flush surface 

with high pressure stream; 

dose with chlorine; increase 

surface area (RBC) 

Check venting; preaerate 

wastewater 

Remove sludge more often 

Reduce recycle; provide flow 

buffering

Table 6-20 presents a listing of potential disinfectants for onsite 

application. Selection of the best disinfectant is dependent upon the 

characteristics of the disinfectant, the characteristics of the 

wastewater and the treatment processes preceding disinfection. The most 

important disinfectants for onsite application are chlorine, iodine, 

ozone, and ultraviolet light, since more is known about these 

disinfectants and equipment is available for their application. 

TABLE 6-20 

SELECTED POTENTIAL DISINFECTANTS FOR ONSITE APPLICATION 

Disinfectant 

Sodium Hypochlorite 

Calcium Hypochlorite 

Elemental Iodine 

Ozone 

Ultraviolet Light 

Formula Form Used Equipment 

NaOCl Liquid 

Ca(OC112 Tablet 

12 

03 

Crystals 

Gas 

Electromagnetic 

Radiation 

Metering Pump 

Tablet Contactor 

Crystal/Liquid 

Contactor 

Generator, Gas/ 

Liquid Contactor 

Thin Film 

Radiation 

Contactor 

Disinfection processes for onsite disposal must necessarily be simple 

and safe to operate, reliable, and economical. They normally are the 

terminal process in the treatment flow sheet. 

6.5.2 The Halogens - Chlorine and Iodine 


Chlorine and iodine are powerful oxidizing agents capable of oxidizing 

organic matter, including organisms, at rapid rates in relatively low 

concentrations. Some of the characteristics of these halogens appear in 

Table 6-21 (20)(441(45). 

163

TABLE.6-21 

HALOGEN PROPERTIES (27) 

Commercial 

Strength Specific 

Handling 

Halogen Form Available % 

Gravity Materials 

Sodium Liquid 12 - 15 1.14 - 1.17 

Hypochlorite 

Ceramic, Glass, 

Plastic, 

Rubber 

Calcium Tablet 70 Glass, Wood, 

Hypochlorite (115 gm) Fiberglass, 

Rubber 

Iodine Crystals 100 4.93 Fiberglass, Some 

Plastics 


Deteriorates rapidly at 

high temperatures, in 

sunlight, and at high 

concentrations. 

Deteriorates at 

3-%/year 

Stable in water; 

solubility: 

10' - 200 mg/l 

20” - 290 mg/l 

30” - 400 mp/l 

Chlorine may be added to wastewater as a gas, Cl . However, because the 

gas can represent a safety hazard and is hig 8 ly corrosive, chlorine 

would normally be administered as a solid or liquid for onsite applications. 

Addition of either sodium or calcium hypochlorite to wastewater 

results in an increase in pH and produces the chlorine compounds hypochlorous 

acid, HOCl, and hypochlorite ion, OCl', which are designated as 

"free" chlorine. In wastewaters containing reduced compounds such as 

sulfide, ferrous iron, organic matter, and ammonia, the free chlorine 

rapidly reacts in nonspecific side reactions with the reduced compounds, 

producing chloramines, a variety of chloro-organics, and chloride. Free 

chlorine is the,most powerful disinfectant, while chloride has virtually 

no disinfectant capabilities. The other chloro-compounds, often called 

combined chlorine, demonstrate disinfectant properties that range from 

moderate to weak. Measurement of "chlorine residual" detects all of 

these forms except chloride. The difference between the chlorine dose 

and the residual, called "chlorine demand," represents the consumption, 

of chlorine by reduced materia1.s in the wastewater (Table 6-22). Thus, 

in disinfection system design, it is the chlorine residual (free and 

combined) that is of importance in destroying pathogens. 

164

TABLE 6-22 

CHLORINE DEMAND OF SELECTED DOMESTIC WASTEWATERSa 

a Estimated concentration of chlorine consumed in nonspecific 

side reactions with 15-minute contact time. 

Chlorine 

Demand 

-Fin--- 

8 - 15 

30 - 45 

10 - 25 

1 - 5 

Iodine is normally used in the elemental crystalline form, I , for water 

and wastewater disinfection. Iodine hydrolyzes in water to f arm the hy- 

poiodus forms, HI0 and IO’, and iodate, I03. Normally, the predominant 

disinfectant species in water are 12, HIO, and IO’, as little IO3 will 

be found at normal wastewater pH values (less than pH 8.0). Iodine does 

not appear to react very rapidly with organic compounds or ammonia in 

wastewaters. As with chlorine, however, most wastewaters will exhibit 

an iodine demand due to nonspecific side reactions. The reduced form of 

iodine, iodide, which is not an effective disinfectant, is not detected 

by iodine residual analyses. 


The halogens are probably the most practical disinfectants for use in 

onsite wastewater treatment applications. They are effective against 

waterborne pathogens, reliable, easy to apply, and are readily avail- 

able. 

165

The use of chlorine as a disinfectant may result in the production of 

chlorinated by-products which may be toxic to aquatic life. No toxic 

by-products have been identified for iodine at this time. 

6.5.2.3 Performance 

The performance of halogen disinfectants is dependent upon halogen re- 

sidual concentration and contact time, wastewater characteristics, na- 

ture of the specific pathogen, and wastewater temperature (20). Waste- 

water characteristics may effect the selection of the halogen as well as 

the required dosage due to the nonspecific side reactions that occur 

(halogen demand). Chlorine demands for various wastewaters are pre- 

sented in Table 6-22. The demand of wastewaters for iodine is less 

clear. Some investigators have reported iodine demands 7 to 10 times 

higher than those for chlorine in wastewaters (46)(47) while others 

indicate that iodine should be relatively inert to reduced compounds 

when compared to chlorine (48). Design of halogen systems is normally 

based upon dose-contact relationships since the goal of disinfection is 

to achieve a desired level of pathogen destruction in a reasonable 

length of time with the least amount of disinfectant. Because of the 

nonspecific side reactions that occur, it is important to distinguish 

between halogen dose and halogen residual after a given contact period 

in evaluating the disinfection process. 

Table 6-23 provides a summary of halogen residual-contact time informa- 

tion for a variety of organisms (43). These are average values taken 

from a number of studies and should be used with caution. Relationships 

developed between disinfectant residual, contact time, and efficiency 

are empirical. They may be linear for certain organisms, but are often 

more complex. Thus, it is not necessarily true that doubling the con- 

tact time will halve the halogens residual requirements for destruction 

of certain pathogens. In the absence of sufficient data to make these 

judgements, conservative values are normally employed for residual-dose 

requirements. 

The enteric bacteria are more sensitive to the halogens than cysts or 

virus. Thus, the use of indicator organisms to judge effective disin- 

fection must be cautiously employed. 

Temperature effects also vary with pathogen and halogen, and the general 

rule of thumb indicates that there should be a two to threefold decrease 

in rate of kill for every loo C decrease in temperature within the 

limits of 5 to 30' C. 

166

TABLE 6-23 

PERFORMANCE OF HALOGENS AND OZONE AT 25°C [After (43)1 

Halogen 

HOC1 (Predominates 

(h pH (7.5) 

OCL- (Predominates 

Q pH >7.5) 

Necessary Residual After 10 Min. to 

Achieve 99.999% Destruction (mg/l) 

Amoebic tnteric Entenc 

cysts Bacteria Vi rus 

3.5 0.02 0.4 

40 1.5 100 

NH2Cla 20 4 20 

12 (Predominates 

8 pH (7.0) 

3.5 0.2 15 

HIO/IO- (Predominates 7 0.05 0.5 

8 8.0>pH>7.0) 

03 0.3->1.8 0.2-0.3 0.2-0.3 

a NHC12:NH2Cl Efficiency = 3.5~1 

6.5.2.4 Design Criteria 

The design of disinfection processes requires the determination of the 

wastewater characteristics, wastewater temperature, pathogen to be de- 

stroyed, and disinfectant to be employed (20). From this information, 

the required residual-concentration relationship may be developed and 

disinfectant dose may be calculated. 

Wastewater characteristics dictate both halogen demand and the species 

of the disinfectant that predominates. In effluents from sand filters, 

chlorine demands would be low and, depending upon pH, hypochlorous acid 

or hypochlorite would prevail if chlorine is used. (The effluent would 

be almost completely nitrified, leaving little ammonia available for 

reaction). At pH values below 7.5, the more potent free chlorine form, 

167

HOC1 , would predominate. It is clear from Table 6-23 that pH plays an 

important role in the effectiveness of chlorine disinfection against 

virus and cysts (10 to 300 fold differences). 

The effect of temperature is often ignored except to ensure that conser- 

vatively long contact times are selected for disinfection. Temperature 

corrections are necessary for estimating iodine doses if a saturator is 

employed, since the solubility of iodine in water decreases dramatically 

with decreased temperature. 

Design of onsite wastewater disinfection systems must result in conser- 

vative dose-contact time values, since careful control of the process is 

not feasible. Guidelines for chlorine and iodine disinfection for on- 

site applications are presented in Table 6-24. These values are guide- 

lines only, and more definitive analysis may be warranted in specific 

cases. 

TABLE 6-24 

HALOGEN DOSAGE DE SIGN GUIDELINES 

Dosea 

Septic Tank Package Biological Sand Filter 

Disinfectant Effluent Process Effluent Effluent 

Wl mgfl w/l 

Chlorine 

-pH 6 

PH 7 

pH 8 

Iodi neb 

pH 6-8 

35-50 15-30 2-10 

40-55 20-35 10-20 

50-65 30-45 20-35 

300-400 go-150 10-50 

a Contact time = 1 hour at average flow and 20°C; increase 

contact time to 2 hours at 10°C and 8 hours at 5°C for similar 

efficiency. 

b Based upon very small data base, assuming iodine demand from 

3 to 7 times that of chlorine. 

168

The sizing of halogen feed systems is dependent upon the form of the 

halogen used and the method of distribution. Sample calculations are 

presented below. 

Sample calculations: 

Estimate of sodium hypochlorite dose - liquid feed 

Halogen: NaOCl - trade strength 15% (150 g/l) 

Dose required: 20 mg/l available chlorine 

Wastewater flow: 200 gpd average 

1. Available chlorine = 

(150 g/l) x (3.785 l/ga 

2. Dose required = 

(20 mg/l) x (3.785 l/ga 

= 1.67 x 10s4 lb/gal 

3. Dose required = 

(1.67 x 1O-4 

4. NaOCl dose = 

(3.34 x 1o-2 

) x (1.0 lb/453.6 g) = 1.25 lb/gal 

) x (1 lb/453.6 g) x (10m3 g/mg) 

b/gal) x (200 gal/d) = 3.34 x 10m2 lb/d 

b/d) + (1.25 lb/gal) = 0.027 gal/day 

Estimate of haloqen desian - tablet feed 

Halogen: Ca(OCL) tablet - 115 g; commercial strength 70% 

Dose Required: 29 mg/l available chlorine 

Wastewater Flow: 200 gpd (750 l/d) 

1. Available chlorine in tablet = 0.7 x 115(g) = 80.5 g/tablet 

2. Dose required = 20 (mg/l) x 750 (l/d) = 15 g/d 

3. Tablet consumption = B 

or: 5.4 days/tablet 

15 (g/d) 

. 5 ( g,tab,et] = 0.19 tab1 ets/day 

169


a. Feed Systems 

There are basically three types of halogen feed systems commercially 

available for onsite application: stack or tablet feed systems, liquid 

feed systems, and saturators. Tablet feed devices for Ca(OCl)2 

tablets (Figure 6-13) are constructed of durable, corrosion-free plastic 

or fiberglass, and are designed for in-line installation. Wastewater 

flows past the tablets of Ca(OCl)2, dissolving them in proportion to 

flow rate (depth of immersion). Tablets are added as requried upon 

manual inspection of the unit. One commercial device provides 29-115 

g/tablet per tube which would require refilling in approximately 155 

days (5.4 days/tablet x 29). 

Halogens may also be fed to the wastewater by an aspirator feeder or a 

suction feeder. The aspirator feeder operates on a simple hydraulic 

principle that employs the use of the vacuum created when water flows 

either through a venturi tube or perpendicular to a nozzle. The vacuum 

created draws the disinfection solution from a container into the disin- 

fection unit, where it is mixed with wastewater passing through the 

unit. The mixture is then injected into the main wastewater stream. 

Suction feeders operate by pulling the disinfection solution from a 

container by suction into the disinfection unit. The suction may be 

created by either a pump or a siphon. 

The storage reservoir containing the halogen should provide ample volume 

for several weeks of operation. A l-gal (4-l) storage tank would hold 

sufficient 15% sodium hypochlorite solution for approximately 37 days 

before refill (see sample computation). A 2-gal (8-l) holding tank 

would supply 50 days of 10% sodium hypochlorite. A 15% sodium 

hypochlorite solution would deteriorate to one-half its original 

strength in 100 days at 25°C (49). The deterioration rate of sodium 

hypochlorite decreases with decreased strength; therefore, a 10% 

solution would decrease to one-half strength in about 220 days. 

If liquid halogen is dispersed in this fashion, care must be taken to 

select materials of construction that are corrosion-resistant. This 

includes storage tanks, piping, and appurtenances as well as the pump. 

Iodine is best applied to wastewater by means of a saturator whereby 

crystals of iodine are dissolved in carriage water subsequent to being 

pumped to a contact chamber (Figure 6-14). Saturators may be con- 

structed or purchased commercially. The saturator consists of a tank of 

fiberglass or other durable plastic containing a supporting base medium 

170

Water Inlet 

FeedTubes 

FIGURE 6-13 

STACK FEED CHLORINATOR 

R 

“"i 1 -I 

171 

I \ Water Outlet

e 


FIGURE 6-14 

IODINE SATURATOR 

Tank 

172 

t 

Iodine Solution 

Iodine Crystals

and iodine crystals. Pretreated wastewater is split, and one stream is 

fed to the saturator. The dissolution of iodine is dependent upon water 

temperature, ranging from 200 to 400 mg/l (Table 6-21). The iodine 

solution from the saturator is subsequently blended with the wastewater 

stream, which is discharged to a contact chamber. Depending upon 

saturator size and dosage requirements, replenishment of iodine every 1 

to 2 yr may be required (assumes a dosage of 50 mg/l for 750 l/day using 

a 0.2-cu-ft saturator). 

b. Contact Basin 

Successful disinfection depends upon the proper mixing and contact of 

the disinfectant with the wastewater. If good mixing is achieved, a 

contact time of 1 hour should be sufficient to achieve most onsite dis- 

infection objectives when using doses presented in Table 6-24. Where 

flows are low (e.g., under 1,000 gal per day) (3,785 1 per day), contact 

basins may be plastic, fiberglass, or a length of concrete pipe placed 

vertically and outfitted with a concrete base (Figure 6-15). A 48-in. 

(122-cm) diameter concrete section would theoretically provide 6 hr of 

wastewater detention for an average flow of 200 gal per day (757 1 per 

day) if the water depth were only approximately 6 in. (15 cm). A 36-in. 

(91-cm) diameter pipe section provides 6 hr detention at approximately 

12 in. (30 cm) of water depth for the same flow. Therefore, substanti- 

ally longer theoretical detention times than necessary for ideal mixing 

conditions are provided using 36- or 48-in. (91- or 122-cm) diameter 

pipe. This oversizing may be practically justified for onsite 

applications, with low flows, since good mixing may be difficult to 

achieve. 

Contact basins should be baffled in order to prevent serious short- 

circuitinq within the basin. One samole baffling arrangement is illus- 

trated in"Figure 6-15. 

6.5.2.6 Operation and Mainten 

The disinfection system should be des 

maintenance requirements, yet insure 

operation and maintenance of premixed 

consists of replacing chemicals, adjust 

nce 

gned to minimize operation and 

reliable treatment. Routine 

liquid solution feed equipment 

ng feed rates, and maintaining 

the mechanical components. Tablet feed chlorination devices should 

require less frequent attention, although recent experience indicates 

that caking of hypochlorite tablets occurs due to the moisture in the 

chamber. Caking may result in insufficient dosing of chlorine, but may 

also produce excessive dosage due to cake deterioration and subsequent 

spillage into the wastewater stream. Dissolution of chlorine may also 

be erratic, requiring routine adjustment of tablet and liquid elevation 

173

(experience with some units indicates that dissolution rates actually 

increase with decreased flow rates). Routine maintenance of iodine 

saturators includes replacing chemicals, occasionally adjusting feed 

rates, redistributing iodine crystals within the saturator, and 

maintaining mechanical components. 


with 

Disinfectant 

FIGURE 6-15 

SAMPLE CONTACT CHAMBER 

/ConcretePipeSection 

LWooden Baffles 

Process control is best achieved by periodic analysis of halogen resid- 

uals in the contact chamber. The halogen residuals can be measured by 

unskilled persons using a color comparator. Periodic bacteriological 

analyses of treated effluents provide actual proof of efficiency. 

Skilled technicians are required to sample and analyze for indicator 

organisms or pathogens. 

174

It i s estimated that tablet feed chlorinators could be operated with 

approximately 6 unskilled man-hr per yr including monthly chlorine residual 

analyses. Iodine saturator systems and ogen 1iqui d feed systems 

may require 6 to 10 semi- skilled man-hr per yr. Electrical power 

consumption woul d be highly variable depending upon other process pumping 

requirements, as well as the use of metering pumps and controls. 

Chemical requirements will vary, but are estimated to be about 5 to 

25 lb to 11 kg) of iodine and 5 to 15 lb to 7 kg) of available 

chlorine per yr for a family of four. 

6.5.2.7 Other Considerations 

In making a final decision on halogen disinfection, other considerations 

must be included in addition to cost, system effectiveness, and 

bil ity. Without a dechl orination step, orine disinfection may be 

ruled out administratively. Currently, there is no evidence that iodine 

or its compounds are toxic to aquatic life. 

6.5.3 traviolet Irradiation 

6.5.3.1 Desc pt on 

The germicidal properties of ultraviolet (UV) irradiation have been recognized 

for many years UV irradiation has been used for the 

disinfection of water suppl ies here and abroad, and currently finds 

widest appl ication for small water systems for homes, commercial 

1 ishments, aboard ship, and in some industrial water purification systems. 

The use of UV irradiation for wastewater disinfection has only 

recently been seriously studied 

Ultraviolet is germicidal in the wave range of 2,300 to 3,000 

its greatest efficiency being at 2,540 A. Currently, high- intensity, 

1ow-pressure mercury vapor amps emit a percentage of their energy 

at this wave length, making them most efficient for use. The primary 

mode of action of UV is the denaturation of nucleic acids, making it 

especially effective against virus. 

In order to be effective, UV energy must reach the organism to be 

destroyed. Unfortunately, UV energy is rapidly absorbed in water and by 

a variety of organic and inorganic molecules in water. Thus, the transmittance 

or absorbance properties of the water to be treated are critical 

to successful UV disinfection. To achieve disinfection, the water 

to be treated is normally exposed in a thin film to the source. This 

may be accomplished by enclosing the within a chamber, and 

175

directing flow through and around the lamps. It may also be accom- 

plished by exposing a thin film of water flowing over a surface or weir 

to a bank of lamps suspended above and/or below the water surface. 

The lamps are encased within a clear, high transmittance, fused quartz 

glass sleeve in order to protect them. This also insulates the lamps so 

as to maintain an optimum lamp temperature (usually about 105’ F or 

41" C). To ensure maintenance of a very high transmittance through the 

quartz glass enclosure, wipers are usually provided with this equip- 

ment. Figures 6-16 and 6-17 depict a typical UV disinfection lamp 

arrangement currently being used. .There are a number of commercially 

available units that may be applicable to onsite wastewater applica- 

tions. 


Site conditions should not restrict the use of UV irradiation processes 

for onsite application, although a power source is required. The unit 

must be housed to protect it from excessive heat, freezing, and dust. 

Wastewater characteristics limit the applicability of UV equipment since 

energy transmission is dependent upon the absorbance of the water to be 

treated. Therefore, only well-treated wastewater can be disinfected 

with UV. 


The effectiveness of UV disinfection is dependent upon UV power, contact 

time, liquid film thickness, wastewater absorbance, process configura- 

tion, input voltage, and temperature (50)(51)(52). 

The UV power output for a lamp is dependent upon the input voltage, lamp 

temperature, and lamp characteristics. Typically, UV output may vary 

from as low as 68% of rated capacity at 90 volts to 102% at 120 volts. 

Lamp temperatures below and above about 104" F (40' C) also results in 

decreased output. The use of quartz glass enclosures normally ensures 

maintenance of optimum temperature within the lamp. 

Since disinfection by UV requires that the UV energy reaches the organ- 

isms, a measure of wastewater absorbance is crucial to proper design. 

Transmissability is calculated as an exponential function of depth of 

penetration and the absorption coefficient of the wastewater: 

176

FIGURE 6-16 

TYPICAL UV DISINFECTION UNIT 

Mounting Brackets for Easy 

Installation Vertical or Horizontal 

1 

l-L Flow Control Valve \ c)..-,..,,LI, 

nar~~uveau~e 

Power Supply 

Flanged head 

/ 

1-1 f6l ” 

r -1 I 

Sterlizing Chamber 

(see Figure 6-l 7) In TiY?I 

c--r 

u 

U 

a 

Drain Plug 

I 

I 

I--!, P-L- fir 

ra11-3a~t: lvlonitor 

I 

/ 

I 

Solenoid Shut Off Valve 

LJ 

Extension t Inlet 

Warning

FIGURE 6-17 

TYPICAL UV STERILIZING CHAMBER 

Baffles force the water to travel 

tangetially through the chamber in a 

spinning motion around quartz sleeves. 

Sterlizing Chamber 

Ultraviolet light rays are emitted from 

high intensity ultraviolet lamps and 

pass through the quartz sleeves. 

Typical sterilizers employ one to 

twelve lamps per sterilizing chamber. 

178

whe e T is the draction 

cm' 

I: 

at 2,537 A, and 

transmitted, a is 

d is the depth in 

the 

cm. 

absorption 

Typically, 

coefficient 

a very 

in 

highquality 

distilled water will have an absorption coefficient of 0.008, 

where tap water would normally vary from 0.18 to 0.20. Wastewaters polished 

with sand filtration should produce absorption coefficients of 

from 0.13 to 0.20, whereas septic tank effluents may be as high as 0.5. 

Currently, rule of thumb requirements for UV application indicate that 

turbidities should be less than 10 JTU and color less than 15 mg/l. (1 

Jackson Turbidity Unit [JTU] is about equivalent to 1 Formazin Turbidity 

Unit [FTU]). 

The relationship between UV power and contact time is still uncertain. 

Empirical relationships have been used to express the performance of UV 

equipment. Currently the empirical term, microwatt seconds per square 

centimeter (mw sec/cn?), is used (50)(51). 

The required contact time for a given exposure is dictated by the waste- 

water absorbance, film thickness, and the pathogen to be destroyed. 

Typical values of UV dosage for selected organisms appear in Table 6-25. 

This tabulation indicates that a wide spectrum of organisms are about 

equally sensitive to UV irradiation. There are exceptions to this, ho!- 

ever; Bacillus spores require dosages in $ xcess of 220,000 mw set/cm., 

and protozoan as high as 300,000 mw set/cm . 

One characteristic trait of UV disinfection of water has been the photo- 

reactivation of treated organisms within the wastewater. Exposure of 

the wastewater to sunlight following UV disinfection has produced as 

much as 1.5 log increase in organisms concentration. This phenomena 

does not always occur, however, and recent field tests indicate that 

photoreactivation may not be of significant concern (52). 


There has been little long-term experience with wastewater UV disinfec- 

tion (2)(52)(53). Therefore, firm design criteria are not available. 

One may draw upon water supply disinfection criteria, however, for con- 

servative design (50)(51). 

179

Shigella 

TABLE 6-25 

UV DOSAGE FOR SELECTED ORGANISMS 

Organism Dosage for 99% Kill at a = 0.0 

Salmonella 

Poliovirus 

IIW sec/cm2 

4,000 

6,000 

6,000 

IH Viral Form 8,000 

E. Coli 

Protozoan 

7,000 

180-300,OOOa 

Fecal Coliform 23,000b 

a For 99.9% inactivation. 

b Field studies corrected to a = 0; 99.96% inactivation. 

Wastewater should be pretreated to a quality such that turbidity is less 

than 10 JTU and color is less than 15 mg/l. Intermittent sand filtered 

effluent quality will generally not exceed these limits when properly 

managed. It would be desirable to provide measurement of UV transmit- 

tance in the wastewater on a continuous basis to ensure that sufficient 

UV power reaches the organism to be treated. Dosage values should be 

conservative until more data are available. 

mum UV dose of, 16,000 mw sec/cm2 or kw set/m 

points throughout the disinfection chamber. A maximum depth of penetration 

should be limited to about 2 in. (5 cm) to allow for variation in 

wastewater absorption. The UV lamps should be enclosed in a quartz 

glass sleeve and appropriate-automatic cleaning devices should be provided. 

A UV intensity meter should be installed at a point of greatest 

water depth from the UV tubes,.and an alarm provided to alert the owner 

when values fall below on acceptable level. 

180 

J herefore, a desired mini- 

should be applied at all


Commercially available UV units sold primarily for water supply disin- 

fection are applicable for onsite wastewater disinfection. Most of 

these units are self-contained and employ high-intensity UV irradiation 

over a thin film of water for short contact times. 

The self-contained unit should be installed following the last treatment 

process in the treatment sequence, and should be protected from dust, 

excessive heat, and freezing. It should be accessible for maintenance 

and control. As described in the previous section, the unit should be 

equipped with a cleaning device (manual or automatic) and an intensity 

meter that is properly calibrated. Flow to the unit should be main- 

tained relatively constant. This is often achieved by means of a pres- 

sure compensated flow control valve. 

Some larger UV modules are available that consist of a series of lamps 

encased within quartz glass enclosures. The module may be placed within 

the flow stream such that all water passes through the module. UV lamps 

positioned over discharge weirs, and therefore out of the water, are 

also available. These systems are not as efficient as flow through 

units since only a fraction of the lamp arc intercepts the water. Con- 

trol of the water film over the weir plate (V-notch or sharp crested) is 

difficult to maintain unless upstream flows are carefully regulated. 

Cleaning and metering devices are required for both of these systems. 

Depending on upstream processes and the UV unit employed, the UV system 

may be operated on a continuous flow or intermittent basis. For small 

flows, self-contained tubular units and intermittent flow would be 

employed. Influent to the unit could be pumped to the UV system from a 

holding tank. In order to obtain full-life expectancy of the UV lamps, 

they should be operated continuously regardless of flow arrangement. 

Where UV modules are employed, continuous flow through the contact 

chamber may be more practical. 


Routine operational requirements include quartz glass enclosure clean- 

ing, lamp replacement, and UV intensity meter reading. Since UV disin- 

fection does not produce a residual, the only monitoring required would 

be periodic bacterial' analyses by skilled technicians. Periodic mainte- 

nance of pumping equipment and controls, and cleaning of quartz jackets 

during lamp replacement, would also be required. 

181

Cleaning of quartz glass enclosures is of paramount importance since UV 

transmittance is severely impaired by the accumulation of slimes on the 

enclosures. Cleaning is required at least 3 to 4 times per year at a 

minimum, and more often for systems employing intermittent flow. If 

automatic wipers are employed, the frequency of manual cleaning may be 

reduced to twice per year. Expected lives of lamps are variable, nor- 

mally ranging from 7,000 to 12,500 hours. It is good practice, however, 

to replace lamps every 10 months, or when metered UV intensity falls be- 

low acceptable values. A complete cleaning of quartz glass enclosures 

with alcohol is required during lamp replacement. Based on limited 

operational experience, it is estimated that 10 to 12 man-hr per yr are 

required to maintain the UV system. Power requirements for the UV 

system for design flow rates up to 4 gpm (0.25 l/ set) are approximately 

1.5 kWh/day. 

6.5.4 Ozonation 


Ozone, 0 , a pale blue gas with pungent odor, is a powerful oxidizing 

agent. 1 t is only slightly soluble in water, depending upon temperature, 

and is highly unstable. Because of its instability, ozone must be 

generated on site. 

Ozone is produced by the dissociation of molecular oxygen into atomic 

oxygen with subsequent formation of 0 . It is produced commercially by 

passing an oxygen-containing feed gas ?I etween electrodes separated by an 

insulating material (54)(55). In the presence of a high-voltage, highfrequencygapdischarge, 

ozone is generated from oxygen in the electrode 

Ozone is a powerful disinfectant against virus, protozoan cysts, and 

vegetative bacteria (54)(55)(56)(57). It is normally sparged into the 

water to be treated by means of a variety of mixing and contact devices. 

Because of its great reactivity, ozone will interact with a variety of 

materials in the water, resulting in an ozone demand. The short half- 

life of ozone also results in the rapid disappearance of an ozone resid- 

ual in the treated water. 


Ozone is currently used to disinfect water supplies in the United States 

and Europe, and is considered an excellent candidate as an alternate 

wastewater disinfectant (54)(55)(56)(57). The major drawback to its 

182

widespread use to date has been the expense of generation. There is no 

documented long-term field experience with ozone disinfection onsite. 

Since ozone is a highly corrosive and toxic gas, its generation and use 

onsite must be carefully monitored and controlled. The generator 

requires an appropriate power source, and must be properly housed to 

protect it from the elements. Wastewater characteristics will have an 

impact on ozone disinfectant efficiency and must be considered in the 

evaluation of this process. 

Data on the effectiveness of ozone residuals against pathogens are 

scant. Employing the same criteria as used for halogens, ozone appears 

to be more effective against virus and amoebic cysts than the halogens 

(Table 6-23). 

The literature indicates that ozone action is not appreciably affected 

by pH variations between 5.0 and 8.0 (58). Turbidity above values of 5 

JTU has a pronounced effect upon ozone dosage requirements, however 

(47)(58). Limited field experience indicates that ozone requirements 

may approximately double with a doubling of turbidity to achieve 

comparable destruction of organisms (47). 

Currently, with very limited operating data, prescribed ozone applied 

dosages recommended for wastewater disinfection vary from 5 to 15 mg/l 

depending upon contactor efficiencies and pathogen to be destroyed. 


The ozone disinfection system consists of the ozone gas generation 

equipment, a contactor, appropriate pumping capacity to the contactor 

and controls. There are two basic types of generating equipment. The 

tube-type unit is an air-cooled system whereby ozone is generated 

between steel electrode plates faced with ceramic. Oxygen-containing 

feed gas may be pure oxygen, oxygen-enriched air, or air. The gas is 

cleaned, usually through cartride-type inpingement filters, and com- 

pressed to about 10 psi. The compressed gas is subsequently cooled and 

then dried prior to being reacted in the ozone contacting chamber. Dry- 

ing is essential to prevent serious corrosion problems within the gener- 

ator. 

The generated ozone-enriched air is intimately mixed with wastewater in 

a contacting device. Ozone contactors include simple bubble diffusers 

in an open tank, packed columns, and positive pressure injection (PPI) 

devices. Detention times within these systems range from 8-15 min in 

283

the bubble diffuser units to lo-30 set in packed columns and PPI systems 

(59)(60). Limited data are currently avail able on long-term use of 

these contactor devices for onsite systems. There are relatively few 

field-tested, small-capacity systems commercially available. 


The ozone disinfection system is a complex series of mechanical and 

electrical units, requiring substantial maintenance, and is susceptible 

to a variety of malfunctions. Since data on long-term experience are 

relatively unavailable, it is not possible to assess maintenance re- 

quirements on air cleaning equipment, compressors, cooling and drying 

equipment, and contactors. It is estimated that 8 to 10 kWh/lb of ozone 

generated will be required (54). Monitoring requirements are similar to 

those for UV disinfection, including occasional bacterial analyses and 

routine ozone monitoring. 

6.6 Nutrient Removal 


6.6.1.1 Objectives 

Nitrogen and phosphorus may have to be removed from wastewaters under 

certain circumstances. Roth are plant nutrients and may cause undesir- 

able growths of plants in lakes and impoundments. Nitrogen may also 

create problems as a toxicant to fish (free ammonia), as well as to ani- 

mals and humans (nitrates). In addition, the presence of reduced nitro- 

gen may create a significant oxygen demand in surface waters. 

Nitrogen may be found in domestic wastewaters as organic nitrogen, as 

ammonium, or in the oxidized form as nitrite and nitrate. The usual 

forms of phosphorus in domestic wastewater include orthophosphate, poly- 

phosphate, pyrophosphate, and organic phosphate. Sources of wastewater 

nitrogen and phosphorus from the home are presented in Table 4-4. 

The removal or transformation of nitrogen and phosphorus in wastewaters 

has been the subject of intensive research and demonstration over the 

past 15 to 20 yr. Excellent reviews of the status of these treatment 

processes can be found in the literature (61)(62). As discussed in 

Chapter 7, the soil may also. serve to remove and/or transform the 

nitrogen and phosphorus in wastewaters percolating through them. 

284

The treatment objective for nitrogen and phosphorus in wastewater is 

dependent upon the ultimate means of disposal. Surface water quality 

objectives may require limitations of total phosphate, organic and 

ammonia nitrogen, and/or total nitrogen. Subsurface water quality 

objectives are less well developed, but may restrict nitrate-nitrogen 

and/or total phosphate. 

6.6.1.2 Application of Nutrient Removal Processes to Onsite 


There are a number of nutrient removal processes applicable to onsite 

wastewater treatment, but there are very little data on long-term field 

applications of these systems. In-house wastewater management through 

segregation and household product selection appears to be the most 

practical and cost-effective method for nitrogen and phosphorus control 

onsite. Septic tanks may remove a portion of these nutrients as flot- 

able and settleable solids. Other applicable chemical, physical, or 

biological processes may also be employed to achieve a given level of 

nutrient removal. Although these supplemental processes may be very 

effective in removing nutrients, they are normally complex and energy 

and labor intensive. 

Since the state-of-the-art application of onsite nutrient removal is 

limited, the discussion that follows is brief. Processes that may be 

successful for onsite application are described. Acceptable design, 

construction, and operation data are presented where they are available. 

6.6.2 Nitrogen Removal 


Table 6-26 outlines the potential onsite nitrogen control options. In 

many instances, these options also achieve other treatment objectives as 

well, and should be evaluated as to their overall performance. The 

removal or transformation of nitrogen within the soil absorption system 

is described fully in Chapter 7. 

6.6.2.2 In-House Segregation 

Chapter 4 provides a detailed description of the household wastewater 

characteristics and sources of these wastewaters. Between 78 and 90% of 

the nitrogen in the wastewater discharged from the home is from toilets. 

Separation of toilet wastewaters would result in average nitrogen levels 

185

TABLE 6-26 

POTENTIAL ONSITE NITROGEN CONTROL OPTIONSa 

Onsite 

Technology 

Status 

Comments 

Effectiveness 

Description 

Option 

Good 

Management of residue 

required 

78-90% removal of N 

in blackwater 

Separate toilet 

wastes from other 

wastewater 

In-House 

Segregation 

Good 

Achieves high level of 

BOD and solids removal 

>90% conversion to 

nitrate 

Granular Filters 

Biological 

Nitri fication 

Good 

May achieve good levels 

of BOD and solids 

removal; labor/energy 

intensive; residue 

management 

85-95% conversion to 

nitrate 

Aerobic package 

plants 

Tentative 

Requires carbon source; 

labor intensive; high 

capital cost 

80-95% removal of N 

Anaerobic 

processes 

following 

nitrification 

Biological 

Denitrifi cation 

Tentative 

Very high operation costs 

>99% removal of NH: 

or NO2 

Cationic 

exchange-NH4 

Ion Exchange 

Anionic 

exchange-NO3 

a Not including the soil absorption system--see Chapter 7.

of about 0.004 lb/cap/day (1.9 mg/cap/day) or 17 mg/l as N in the re- 

maining graywater (Tables 4-4 and 4-5). Chapter 5 describes the process 

features, the performance, and the operation and maintenance of low- 

water carriage and waterless toilet systems. The resultant residuals 

from toilet segregation, whether they be ash, compost, chemical sludge, 

or blackwater, must be considered in this treatment strategy. A dis- 

cussion of residuals disposal is presented in Chapter 9. 

The success of this method of nitrogen removal is dependent upon appro- 

priate management of the in-house segregation fixtures and the disposal 

of the residues from them. These devices must be considered a part of 

the treatment system when developing appropriate authority for institu- 

tional control. 

6.6.2.3 Biological Processes 

Nitrogen undergoes a variety of biochemical transformations depending 

upon its form and the environmental conditions (61). Organic nitrogen 

in domestic wastewaters readily undergoes decomposition to ammonia in 

either aerobic or anaerobic conditions. In an aerobic environment, a 

select group of bacteria oxidize ammonia to nitrite and ultimately 

nitrate. Nitrates may be reduced by a variety of organisms to various 

nitrogen gas under anaerobic conditions. Depending upon the treatment 

objectives, one or several of these processes may be employed to achieve 

the desired end product. 

a. Applicability 

A number of biological processes for nitrogen conversion are applicable 

to onsite treatment. Domestic wastewater characteristics should not 

limit application of these processes, provided the nitrogen is in the 

appropriate for-m for conversion. Since biological processes are tem- 

perature-sensitive, such systems should be covered and insulated in cold 

climates. Covering also contains odors, should problems occur. 

b. Process Performance 

Although data are sketchy, about 2 to 10% of the total nitrogen from the 

home may be removed in the septic tank with septage (63)(64). Approxi- 

mately 65 to 75% of the total nitrogen in septic tank effluents is in 

the ammonia-nitrogen form, indicating a significant level of decomposi- 

tion of organic nitrogen (2). 

187

Nitrification of septic tank effluents occurs readily within intermit- 

tent sand filters (see Section 6.3). Field expfrience ingicstes that 

intermittent sand filters loaded up to 5 gpd/ft (0.02 cm /m /d), and 

properly maintained to avoid excessive ponding (and concomitant anaero- 

bic conditions), converts up to 99% of the influent ammonia to nitrate- 

nitrogen (2). Aerobic biological package plants also provide a high 

degree of nitrification, provided solids retention times are long and 

sufficient oxygen is available (see Section 6.6). 

The biological denitrification (nitrates to nitrogen gases) of waste- 

water follows a nitrification step (61). There has been little experi- 

ence with long-term field performance of onsite denitrification pro- 

cesses. Ideally, total nitrogen removal in excess of 90% should be 

achievable, if the system is properly operated and maintained (61). 

C. Design- and Construction Features 

Septi;*Tanis: There are no septic tank design requirements specifically 

estab lshe to enhance high levels of nitrogen removal. Designs that 

provide excellent solid-liquid separation ensure lower concentrations of 

nitrogen associated with suspended solids. 

Nitrification: Biological nitrification is achieved by a select group 

of aerobic ml'croorganisms referred to as nitrifiers (61). These organ- 

isms are relatively slow-growing and more sensitive to environmental 

conditions than the broad range of microorganisms found in biological 

wastewater treatment processes. The rate of growth of nitrifiers (and 

thus the rate of nitrification) is dependent upon a number of parame- 

ters, including temperature, dissolved oxygen, pH, and certain toxi- 

cants. The design and operating parameter used to reflect the growth 

rates of nitrifiers is the solids retention time (SRT). Details of the 

impact of temperature, dissolved oxygen, pH, and toxicants on design SRT 

values for nitrification systems are outlined in reference (61). In 

brief, biological nitrification systems are designed with SRT values in 

excess of 10 days; dissolved oxygen concentrations should be in excess 

of 2.0 mg/l; and pH values should range between 6.5 and 8.5. Toxicants 

known to be troublesome are discussed in reference (61). 

Details of the design and construction of intermittent sand filters and 

aerobic package plants are found in Sections 6.3 and 6.4. In general, 

designs normally employed for onsite application of these processes to 

remove BOD and solids are sufficient to encourage nitrification as well. 

Denitrification: Biological denitrification is carried out under anoxic 

conditions in the presence of facultative, heterotrophic microorganisms 

188

which conve.rt nitrate to nitrogen gases (61). Numerous microorganisms 

are capable of carrying out this process, provided there is an organic 

carbon source available. These organisms are less sensitive to environ- 

mental conditions than the nitrifiers, but the process is temperature- 

dependent. Process design and operational details for conventional de- 

nitrification processes are discussed in reference (61). 

Design and operational experience with onsite biological denitrification 

systems is limited at this time (2)(65)(66). Several systems have been 

suggested for onsite application, two of which are shown in Figure 6- 

18. One employs a packed bed containing approximately 3/8-in. (l-cm) 

stone that receives, on a batch basis, effluent from a nitrification 

process. The nitrified wastewater flows to a dosing tank, where it is 

held until a predetermined volume is obtained. Methanol (or other or- 

ganic carbon source) is then added to provide a C:N ratio of approxi- 

mately 3:l. After approximately 15 min, the wastewater is pumped up 

through the anoxic packed stone bed. Effluent flows from the top of the 

bed. Liquid retention times in the packed bed (based on void volume) 

varying from 12 to 24 hours have been employed with good results (2). 

Pumping may be provided by a l/3-hp submersible pump actuated by a 

switch float within the sump. A small chemical feed pump controlled by 

a timer switch may be used to feed the organic carbon source to the 

sump. A 30% methanol solution may be used as the carbon source. Other 

organic carbon sources include septic tank effluent, graywater, and 

molasses. Metering of organic carbon source to the nitrified wastewater 

requires substantial control to ensure a proper C:N ratio. Insufficient 

carbon results in decreased denitrification rates, whereas excess carbon 

contributes to the final effluent BOD (61). The use of an easily ob- 

tainable, slowly decomposable, solid carbon source could also be con- 

sidered. Peat, forest litter, straw, and paper mill sludges, for exam- 

ple, could be incorporated as a portion of the upflow filter. Control 

of the denitrification process using these solid carbon sources would be 

difficult. 

Another onsite nitrification-denitrification system that has been field 

tested employs a soil leach field (66) (Figure 6-18). Septic tank ef- 

fluent is distributed to a standard soil absorption field. An imperme- 

able shield of fiberglass is placed approximately 5 ft (1.5 m) below the 

distribution line. The location of this collector should be deep enough 

to ensure complete nitrification within the overlying unsaturated soil. 

The nitrified wastewater is collected on the sloped fiberglass shield, 

and directed to a 24-in. (61-cm) deep bed of pea gravel contained within 

a plastic liner (denitrifying reactor). The gravel bed is sized deep 

enough to provide a hydraulic detention time of approximately 10 days 

(based on void volume). Methanol or other energy source is metered to 

the gravel bed through a series of distributors. The gravel bed is 

vented with vertical pipes to allow escape of nitrogen gas evolved in 

the process. Short-term experience with this system has been good. 

Total nitrogen concentrations of less than 1 mg/l-N were achievable in 

189

Influe? 

Effluent 

0 

Tank 


Tank - 

FIGURE 6-18 

ONSITE DENITRIF ICATION SYSTEMS 

Batch Denitrification 

Methanol 

,-Pump and 

Fro 

N itrifvinn 

Float 

Control 

Pump 

L Impermeable Liner 

Nitrification-Denitrification in Soil 

190 

Irn 

Pt ‘ocess

effluent samples during summer months. Higher values (5-10 mg/l-N) were 

observed during the colder winter months. 

Although no studies have been reported in the literature for onsite 

applications, intermittent or cycled extended aeration processes are 

potentially promising (61)(67) for the nitrification-denitrification of 

wastewater. This process makes use of existing proprietary extended 

aeration package plants where aeration is cycled to provide both aerobic 

and anoxic environments. In this mode of operation, sufficient solids 

retention time (SRT) is provided to insure nitrification, and a suffi- 

cient period of anoxic holding is provided to insure denitrification. 

The biomass serves as the energy source for denitrification. The cycle 

times vary dependent on temperature and wastewater characteristics. A 

typical cycle, using a SRT of 20 days, aerates 180 min and holds anoxic 

for 90 min (67). Nitrogen removals in excess of 50% are attainable with 

this system (2)(67). Operation of the cyclic aeration system requires 

substantial supervision for a period of time until proper sequences have 

been selected. 

d. Operation and Maintenance 

Nitrification Systems: Operation and maintenance requirements to 

achieve nitrification in either intermittent sand filters or aerobic 

package units are not significantly different from those discussed in 

Sections 6.3 and 6.4. In both systems, the process must be maintained 

in an aerobic condition at all times to ensure effective nitrification. 

Denitrification Systems: Operation and maintenance requirements ,.for 

denitrification systems are normally complex and require semi-skilled 

labor for proper performance. In addition to routine maintenance of 

pumping systems, mixers, and timer controls, the addition and balance of 

a carbon source is required. 

Routine analyses of nitrogen compounds and biological solids is also im- 

portant. Rough estimates for semi-skilled labor for maintenance of an 

onsite denitrification system varies from 15 to 30 man-hr per yr. If 

methanol is used as a carbon source, it is estimated that from 33 to 55 

lb/yr (15 to 25 kg/yr) are required for a family of four. Power re- 

quirements for methanol feed and pumping are about 15 to 25 kWh/yr. 

6.6.2.4 Ion Exchange 

Ion exchange is a process whereby ions of a given species are displaced 

from an insoluble exchange material by ions of a different species in 

191

solution. It can be used to remove either ammonium or nitrate nitrogen 

from wastewaters. This process has been employed in full-scale water 

and wastewater treatment plants for several years (61)(67)(68), but 

there is no long-term experience with the process for nitrogen removal 

in onsite applications. 

Nitrogen removal by ion exchange has potential for onsite application, 

since it is very effective and is simple to operate. Unfortunately, per- 

iodic replacement of the exchange media is expensive and regeneration of 

the media onsite does not appear to be practical at this time. Site 

conditions and climatological factors should not limit its application. 

a. Ammonia Removal 

Ammonia removal may be achieved by employing the naturally occurring ex- 

change media, clinoptilolite, which has a high affinity for the ammonium 

ion (61). Laboratory experience has shown that packed columns of cli- 

noptilolite resin (20 x 40 mesh) will effectively remove ammonium ion 

from septic tank effluent without serious clogging problems (2). Regen- 

eration with 5% NaCl was successful over numerous trials. BreaktQrough 

exchange capacity of this resin was found to be about 0.4 meq NH4 /gram 

in hard water at application rates of 10 bed volumes per hr. (This 

value will vary, increasing with decreased hardness.) Very large quan- 

tities of resin are required to treat household wastewaters (approxi- 

mately 10 lb per day). Treatment of segregated graywaters substantially 

lower in ammonium concentration decreases the amount of resin needed. 

This process employs a packed column or bed of the exchange resin fol- 

lowing a septic tank. The waste is pumped from a sump to the column in 

an upflow or downflow mode on a periodic basis. Once the resin has been 

exhausted, it is removed and replaced by fresh material. Regeneration 

occurs offsite. 

Operation and maintenance of this process requires routine maintenance 

of the pump and occasional monitoring of ammonium levels from the pro- 

cess. Replacement of exhausted resin is dictated by wastewater charac- 

teristics and bed volume. There are insufficient data at this time to 

delineate labor, power, and resin requirements. 

b. Nitrate Removal 

Nitrate removal from water may be achieved by the use of strong and weak 

base ion exchange resins (68)(69). There are very little data available 

192

on long-term performance of these nitrate removal systems for waste- 

water. Numerous anions in water compete with nitrate for sites on these 

resins; therefore, tests on the specific wastewater to be treated need 

to be performed. 

This process has potential for onsite application, where it would follow 

a nitrification process such as intermittent sand filters. As with 

ammonia resins, regeneration is performed off site. 

There is insufficient information on nitrate exchange to provide design, 

construction, operation, and maintenance data at this time. 

6.6.3 Phosphorus Removal 


Table 6-27 outlines the most likely treatment processes available for 

onsite removal of phosphorus in wastewater. In many instances, these 

processes will also achieve other treatment objectives as well, and must 

be evaluated as to their overall performance. 

6.6.3.2 In-House Processes 

Review of Chapter 4 indicates that the major sources of phosphorus in 

the home are laundry, dishwashing, and toilet wastewaters. Contribu- 

tions of phosphorus in the home could be reduced from approximately 4 to 

2 gm/cap/day through the use of 0.5% phosphate detergents. 

Segregation of toilet wastewaters (blackwater) from household waste- 

waters reduces phosphorus levels to approximately 2.8 gm/cap/day in the 

graywater stream. Chapter 4 describes the process features, perfor- 

mance, and operation and maintenance of low-water carriage and waterless 

toilet systems that would be employed for this segregation. Note that 

the resultant residues from these toilet systems must be considered in 

this treatment strategy. A discussion of residuals disposal appears in 

Chapter 9. 

As with any in-house measure to reduce pollutional loads, the success of 

the process is dependent upon owner commitment and appropriate manage- 

ment of the alternative plumbing equipment. 

193

TABLE 6-27 

POTENTIAL ONSITE PHOSPHORUS REMOVAL OPTIONS 

Onsite 

Technology 

Status 

Effectiveness Comments - 

Descriotion 

Option 

Excellent 

0.5% P detergents 

available 

50% P 

removal 

In-House Laundry detergent 

Segregation substitution 

Good 

Management of residues 

required; achieves 

significant BOD, SS 

reduction 

20-40% P 

removal 

Separate toilet 

wastes from other 

wastewaters 

Fair 

Increases quantity of 

sludge; labor intensive 

up to 90% P 

removal 

Dosing prior to 

or following 

septic tanks 

Chemical 

Precipitation: 

Iron, Calcium 

and Aluminum 

Salts 

w 

co 

P 

Replacement required Tentative 

up to 90% P 

removal 

Beds or columns 

Sorption 

Processes: 

Calcite or Iron 

Tentative 

High cost for material, 

labor intensive 

go-99% P 

removal 

Beds or columns 

Alumina

6.6.3.3 Chemical Precipitation 

Phosphorus in wastewater may be rendered insoluble by a selected number 

of metal salts, including aluminum, calcium, and iron (62). Although 

the reactions are complex, the net result is the precipitation of an 

insoluble complex that contains phosphate. Phosphorus precipitation 

methods normally include the addition of the chemical, high-speed 

mixing, and slow agitation followed by sedimentation. 

There has been little long-term experience with phosphorus removal of 

wastewaters onsite (21170). Precipitation of phosphates is less easily 

accomplished for polyphosphates and organic phosphorus than for ortho- 

phosphate. Therefore, precipitation within the septic tanks, although 

simpler to manage, may not remove a significant portion of the phos- 

phate, which is in the poly and organic form. Substantial hydrolysis of 

these forms may occur in the septic tank, however, producing the ortho- 

form. Thus, precipitation following the septic tank may achieve higher 

overall removals of total phosphorus. 

Performance is dependent on the point of chemical addition, chemical 

dosage, wastewater characteristics, and coagulation and sedimentation 

facilities. Dose-performance relationships must be obtained through 

experimentation, but one should expect phosphorus removals between 75 

and 90%. Improvement in this performance may be achieved if intermit- 

tent sand filters follow the precipitation/sedimentation process. Side 

benefits are achieved with the addition of the precipitating chemicals. 

Suspended and colloidal BOD and solids will be carried down with the 

precipitate, producing a higher quality effluent than would otherwise be 

expected. 

Chemical precipitation of wastewaters generates more sludge than do 

conventional systems due to both the insoluble end product of the added 

chemical and the excess suspended and colloidal matter carried down with 

it. Estimates of this increased quantity are very crude at this time, 

but may range from 200 to 300% by weight in excess of the sludge nor- 

mally produced from a septic tank system. 

a. Process Features 

The chemicals most often used for phosphate precipitation are aluminum 

and iron compounds. Calcium salts may also be used, but require pH ad- 

justment prior to final discharge to the environment. Aluminum is gen- 

erally added as alum (A12S04'n H20). Ferric chloride and ferric sulfate 

are the most commonly used iron salts. 

195

Anionic polyelectrolytes can be used in combination with the aluminum 

and iron salts to improve settling, but may overly complicate the onsite 

treatment system. 

The required dosages of aluminum and iron compounds are generally re- 

ported as molar ratios of trivalent metal salt to phosphate phosphorus. 

Molar ratios currently used in practice today range from 1.5:1 to 4:1, 

depending upon wastewater characteristics, point of addition, and de- 

sired phosphorus removal (20)(62). 

Adding aluminum or iron salts to the raw wastewater prior to the septic 

tank has the advantage of using the existing septic tank for sedimenta- 

tion (70). Aluminum or iron salts may be metered to the raw wastewater 

with a chemical feed pump activated by electrical or mechanical impulse. 

Mixing of the chemical with the wastewater is provided in the sewer line 

to the septic tank. The quantity of metal salt added to.the wastewater 

is dependent upon wastewater characteristics. Since the impulse to the 

feed pump may come from any of a number of household events, it is not 

possible to precisely adjust metal dosage. An average dose of salt 

based on estimated phosphorus discharge is most practical. 

Addition of iron or aluminum salts following the septic tank may also be 

considered. A batch -feed system could be employed whereby a preset 

chemical dose is provided when the wastewater reaches a preset volume in 

a holding tank. Mixing may be provided by aeration or mechanical mixer, 

followed by a period of quiescence. Additional raw wastewater flow 

would be diverted to a holding tank until the precipitation-sedimenta- 

tion cycle is completed. This system may be employed after the septic 

tank and preceding the intermittent sand filter. 

The processes briefly described above represent a few of the many chemi- 

cal treatment processes that might be considered for onsite treatment. 

They may be designed and constructed to fit the specific needs of the 

site, or purchased as a proprietary device. Storage and holding of 

chemicals must be considered in the design of these systems. Details on 

chemical storage, feeding, piping, and control systems may be found 

elsewhere (20)(62). Attention must be given to appropriate materials 

selection, since many of the metal salts employed are corrosive in 

liquid form. 

b. Operation and Maintenance 

Every effort should be made to select equipment that is easily operated 

and maintained. Nonetheless, chemical precipitation systems require 

semi-skilled labor to maintain chemical feed equipment, mixers, pumps, 

196

and electronic or mechanical controls. More frequent pumping of waste- 

water sludge or septage is also required. A rough estimate for semi- 

skilled labor is 10 to 25 man-hr per yr depending upon the complexity of 

the equipment. Conservative estimates on sludge accumulation dictate 

sludge or septage pumping every 0.5 to 2 years for an average home. 

Chemical requirements would vary widely, but are estimated to range from 

22 to 66 lb/yr Al (10 to 30 kg/yr) or 11 to 33 lb/yr Fe (5 to 15 kg/yr) 

for a family of four. 

6.6.3.4 Surface Chemical Processes 

Surface chemical processes, which include ion exchange, sorption, and 

crystal growth reactions, have received little application in treatment 

of municipal wastewaters, but hold promise for onsite application (62). 

These types of processes are easy to control and operate; the effluent 

quality is not influenced by fluctuations in influent concentration; and 

periods of disuse between applications should not affect subsequent per- 

formance. Phosphorus removal on selected anion exchange resins has been 

demonstrated, but control of the process due to sulfate competition for 

resin sites has discouraged its application (71). Phosphorus removal by 

sorption in columns or beds of calcite or other high-calcium, iron, or 

aluminum minerals is feasible; but long-term experience with these mate- 

rials has been lacking (2)(25)(72). Many of these naturally occurring 

materials have limited capacity to remove phosphorus, and some investi- 

gations have demonstrated the development of biological slimes that 

reduce the capacity of the mineral to adsorb phosphorus. Table 6-28 

lists a range of phosphorus adsorption capacities of several materials 

that may be considered. The use of locally available calcium, iron, or 

aluminum as naturally occurring materials, or as wastewater products 

from industrial processing, may prove to be cost-effective; but trans- 

port of these materials any distance normally rules out their widespread 

application. Incorporation of phosphate-sorbing materials within 

intermittent sand filters is discussed more fully in Section 6.3.5. 

The use of alumina (Al2O3), a plentiful and naturally occurring material 

for sorption of phosphorus, has been demonstrated in laboratory studies, 

but has not yet been employed in long-term field tests (75). Alumina 

has a high affinity for phosphorus, and may be regenerated with sodium 

hydroxide. Application of an alumina sorption process is similar to ion 

exchange, whereby a column or bed would be serviced by replacement on a 

routine basis. Costs for this process are high. 

6.7 Wastewater Segregation and Recycle Systems 

Chapter 5 discusses in detail in-house methods that may be employed to 

modify the quality of the wastewater. These processes are an important 

197

component of the onsite treatment system as they remove significant 

quantities of pollutants from the wastewater prior to further treatment 

and/or disposal. 

TABLE 6-28 

PHOSPHORUS ADSORPTION ESTIMATES FOR SELECTED 

NATURAL MATERIALS (73)(74)(75)a 

Media Adsorption 

(mg P/100 gm media) 

Acid Soil Outwash 10 - 35 

Calcereous Soil Outwash 5 - 30 

Sandy Soils 2 - 20 

~-1 Alumina (A1203), 24-48 mesh 700 - 1500 

a Based on maximum Langmuir isotherm values. 

6.7.1 Wastewater Segregation 

Among the wastewater segregation components which significantly alter 

wastewater quality are the non-water carriage toilets (Table 5-3), and 

the very low water flush toilets (Table 5-2) with blackwater contain- 

ment. Impacts of wastewater modification on onsite disposal practices 

are outlined in Table 5-9. 

The graywater resulting from toilet segregation practices normally re- 

quire some treatment prior to ,disposal (Tables 4-4 and 4-5 - "Basins, 

Sinks, and Appliances"). Treatment methods for graywater are similar to 

those employed for household wastewaters (Sections 6.2 to 6.6 and Figure 

5-2), but performance data are lacking. 

198

Residuals resulting from the treatment or holding of segregated waste 

streams must be considered when evaluating these alternatives. Details 

of the characterization and disposal of these residuals appear in 

Chapter 9. 

6.7.2 Wastewater Recycle 

In-house wastewater recycle systems are treatment systems employed to 

remove specific pollutants from one or more wastewater streams in order 

to meet a specific water use objective (for example, graywater may be 

treated to a quality that is acceptable for flushing toilets, watering 

lawns, etc.). These systems are summarized in Table 5-6. 

The impact of recycle systems on the quality of wastewater to be ulti- 

mately disposed is difficult to assess at this time owing to the absense 

of long term experience with these systems. It is likely that substan- 

tial pollutant mass reduction will occur in addition to flow reduction. 

As with segregated systems, the disposal of residuals from these pro- 

cesses must be considered in system evaluation. 

6.8 

1. 

2. 

3. 

4. 

5. 

6. 

References 

Jones, E. E. Septic Tank - Configuration versus Performance. Pre- 

sented at the 2nd Pacific Northwest On-Site Wastewater Disposal 

Short Course, University of Washington, Seattle, March 1978. 


Madison. Management of Small Waste Flows. EPA 600/Z-78-173, NTIS 


Weibel, S. R., C. P. Straub, and J. R. Thoman. Studies on House- 

hold Sewage Disposal Systems, Part I. NTIS Report No. PB 217 671, 

Environmental Health Center, Cincinnati, Ohio, 1949. 279 pp. 

Salvato, J. A. Experience with Subsurface Sand Filters. Sewage 

and Industrial Wastes, 27(8):909, 1955. 

Bernhart, A. P. Wastewater from Homes. University of Toronto, 

Toronto, Canada, 1967. 

Laak, R. Wastewater Disposal Systems in Unsewered Areas. Final 

Report to Connecticut Research Commission, Civil Engineering 

Department, University of Connecticut, Storrs, 1973. 

199

7. 

8. 

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

Brandes, M. Characteristics of Effluents from Separate Septic 

Tanks Treating Gray and Black Waters from the Same House. J. Water 


Weibel, S. R., T. W. Bendixen, and J. B. Coulter. Studies on 

Household Sewage Disposal Systems, Part III. NTIS Report No. PB 

217 415, Environmental Health Center, Cincinnati, Ohio, 1954. 150 

PP. 

Plews, G. D. The Adequacy and Uniformity of Regulations for 

On-Site Wastewater Disposal - A State Viewpoint. In: National 

Conference on Less Costly Wastewater Treatment SystKs for Small 

Communities. EPA 600/9-79-010, NTIS Report No. PB 293 254, April 

1977. pp. 20-28. 

Manual of Septic Tank Practices. NTIS Report No. PB 216 240, 

Public Health Service, Washington, D.C., 1967. 92 pp. 

Baumann, E. R., E. E. Jones, W. M. Jakubowski, and M. C. Notting- 

ham. Septic Tanks. In: Proceedings of the Second National Home 

Sewage Treatment Symposium, Chicago, Illinois, December 1977. 


1978. pp. 38-53. 

Weibel, S. R. Septic Tanks: Studies and Performance. Agric. 

Engo, 36:188-191, 1955. 

Harris, S. E., J. H. Reynolds, D. W. Hill, D. S. Filip, and E. J. 

Middlebrooks. Intermittent Sand Filtration for Upgrading Waste 

Stabilization Pond Effluents. J. Water Pollut. Control Fed. 49:83- 

102, 1977. 

Schwartz, W. A., T. W. Bendixen, and R. E. Thomas. Project Report 

of Pilot Studies on the Use of Soils as Waste Treatment Media; In- 

house Report. Federal Water Pollution Control Agency, Cincinnati, 

Ohio, 1967. 

Metcalf, L., and H. P. Eddy. American Sewerage Practice. 3rd ed., 

Volume III. McGraw-Hill, New York, 1935. 892 pp. 

Boyce, E. Intermittent Sand Filters for Sewage. Munic. Cty. Eng., 

72:177-179, 1927. 

Recommended Standards for Sewage Works. Great Lakes-Upper Missis- 

sippi River Board of State Sanitary Engineers, Albany, New York, 

1960. 138 pp. 

Filtering Materials for Sewage Treatment Plants. Manual of Engi- 

neering Practice No. 13, American Society of Civil Engineers, New 

York, 1937. 40 pp. 

200

19. 

20. 

21. 

22. 

23. 

24. 

25. 

26. 

27. 

28. 

29. 

Salvato, J. A., Jr. Experience With Subsurface Sand Filters. Sew. 

Ind. Wastes, 27:909-916, 1955. 

Wastewater Treatment Plant Design. Manual of Practice No. 8, Water 

Pollution Control Federation, Washington, D.C., 1977. 560 p. 

Clark, H. W. and S. Gage. A Review of Twenty-One Years of Experi- 

ments upon the Purification of Sewage at the Lawrence Experimental 

Station. 40th Annual Report, State Board of Health of Massachu- 

setts, Wright E. Potter, Boston, Massachusetts, 1909. 291 pp. 

Brandes, M. Effect of Precipitation and Evapotranspiration on Fil- 

tering Efficiency of Wastewater Disposal Systems. Publication No. 

W70, Ontario Ministry of Environment, Toronto, Canada, May 1970. 

Emerson, D. L., Jr. Studies on Intermittent Sand Filtration of 

Sewage. Florida Engineering and Industrial Experimental Station 

Bulletin No. 9, University of Florida College of Engineering, 

Gainesville, 1954. 

Hines, J., and R. E. Favreau. Recirculating Sand Filter: An 

Alternative to Traditional Sewage Absorption Systems. In: Pro- 

ceedings of the National Home Sewage Disposal Symposium, Chicago, 

Illinois, December 1974. American Society of Agricultural Engi- 

neers, St. Joseph, Michigan, 1975. pp. 130-136. 

Brandes, M., N. A. Chowdhry, and W. W. Cheng. Experimental Study 

on Removal of Pollutants From Domestic Sewage by Underdrained Soil 

Filters. In: Proceedings of the National Home Sewage Disposal 

Symposium, Chicago, Illinois, December 1974. American Society of 

Agricultural Engineers, St. Joseph, Michigan, 1975. pp. 29-36. 

Teske, M. G, Recirculation - An Old Established Concept Solves 

Same Old Established Problems. Presented at the 51st Annual Con- 

ference of the Water Pollution Control Federation, Anaheim, Cali- 

fornia, 1978. 

Bowne, W. C. Experience in Oregon With the Hines-Favreau Recircu- 

lating Sand Filter. Presented at the Northwest States Conference 

on Onsite Sewage Disposal, 1977. 

Chowdhry, N. A. Underdrained Filter Systems - Whitby Experiment 

Station. Ministry of the Environment Interim Report Part 2. 


Kennedy, J. C. Performance of Anaerobic Filters and Septic Tanks 

Applied to the Treatment of Residential Wastewater. M.S. Thesis, 

University of Washington, Seattle, 1979. 

201

30. 

31. 

32. 

33. 

34. 

35. 

36. 

37. 

38. 

39. 

40. 

41. 

42. 

Bernhart, A. P. Wastewater From Homes. University of Toronto, 


Voell, A. T. and R. A. Vance. Home Aerobic Wastewater Treatment 

Systems - Experience in a Rural County. Presented at the Ohio Home 

Sewage Disposal Conference, Ohio State University, Columbus, 1974. 

Tipton, D. W. Experiences of a County Health Department with Indi- 

vidual Aerobic Sewage Treatment Systems. Jefferson County Health 

Department, Lakewood, Colorado, 1975. 

Brewer, W. S., J. Lucas, And G. Prascak. An Evaluation of the 

Performance of Household Aerobic Sewage Treatment Units. Journal 

of Environmental Health, 41:82-85, 1978. 

Glasser, M. B. Garrett County Home Aeration Wastewater Treatment 

Project. Bureau of Sanitary Engineering, Maryland State Department 

of Health and Mental Hygiene, Baltimore, 1974. 

Hutzler, N. J., L. E. Waldorf, and J. Fancy. Performance of Aero- 

bic Treatment Units. In: Proceedings of the Second National Home 

Sewage Treatment Symposium, Chicago, Illinois, December 1977. 


1978. pp. 149-163. 

Operation of Wastewater Treatment Plants. Manual of Practice No. 

11, Water Pollution Control Federation, Washington, D.C., 1976. 

547 pp. 

Tsugita, R. A., D. C. W. Decoite, and L. Russell. Process Control 

Manual for Aerobic Biological Wastewater Treatment Facilities. 

EPA 430/g-77-006, NTIS Report No. PB 279 474, James M. Montgomery 

Inc., 1977. 335 pp. 

Process Design Manual, Wastewater Treatment Facilities for Sewered 

Small Communities. EPA-625/l-77-009, U.S. Environmental Protection 

Agency, Cincinnati, Ohio, 1977. 

Craun, C. F. Waterborne Disease - A Status Report Emphasizing Out- 

breaks in Ground Water Systems. Ground Water, 17:183-191, 1979. 

Craun, C. F. Disease Outbreaks Caused by Drinking Water. J. Water 


Jakubowski, W., and J. C. Hoff, eds. Waterborne Transmission of 

Giardiasis. EPA 600/9-79-001, NTIS Report No. PB 299 265, U. S. 

Environmental Protection Agency, Health Effects Research Labora- 

tory, Cincinnati, Ohio, June 1979. 306 pp. 

Berg, G., ed. Transmission of Viruses by the Water Route. Wiley, 

New York, 1967. 502 pp. 

202

43. Chang, S. L. Modern Concept of Disinfection. J. Sanit. Eng. Div., . 

Am. Sot. Civil Eng., 97:689-707, 1971. 

44. White, G. C. Handbook of Chlorination. Van Nostrand Reinhold, New 

York, 1972. 751 pp. 

45. Morris, J. C. Chlorination and Disinfection: State of the Art. 

J. Am. Water Works Assoc., 63:769-774, 1971. 

46. McKee, J. E. Report on the Disinfection of Seattle Sewerage. Cali- 

fornia Institute of Technology, Pasadena, California, April 1957. 

47. Budde, P. E., P. Nehm, and W. C. Boyle. Alternatives to Wastewater 

Disinfection. J. Water Pollut. Control Fed., 49:2144-2156, 1977. 

48. Black, A. P. Better Tools for Treatment. J. Am. Water Works 

Assoc., 58:137-146, 1966. 

49. Baker, R. J. Characteristics of Chlorine Compounds. J. Water 


50. Jepson, J. D. Disinfection of Water Supplies by Ultraviolet Irra- 

diation. Water Treat. Exam., 22:175-193, 1973. 

51. Huff, C. B., H. F. Smith, W. 0. Boring, and N. A. Clarke. Study of 

Ultraviolet Disinfection of Water and Factors in Treatment Effi- 

ciency. Pub. Health Rep., 80:695,705, 1965. 

52. Scheible, 0. K., G. Binkowski, and T. J. Mulligan. Full Scale 

Evaluation of Ultraviolet Disinfection of a Secondary Effluent. 

: Progress in Wastewater Disinfection Technology, EPA 600/9-79- 

g8 NTIS Report No. PB 299 338, Municipal Environmental Research 

Labiratoty, Cincinnati, Ohio, 1979. pp. 117-125. 

53. Kreissl, J. F., and J. M. Cohen. Treatment Capability of a Physi- 

cal Chemical Package Plant. Water Res., 7:895-909, 1973. 

54. Rosen, H. M. Ozone Generation and Its Economical Application in 

Wastewater Treatment. Water Sew. Works, 119:114-120, 1972. 

55. Johansen, R. P., and D. W. Terry. Comparison of Air and Oxygen 

Recycle Ozonation Systems. Presented at the Symposium on Advanced 

Ozone Technology, Toronto, Canada, November 1977. 

56. Majumdar, S. B., and 0. J. Sproul. Technical and Economic Aspects 

of Water and Wastewater Ozonation: A Critical Review. Water Res., 

8~253-260, 1974. 

57. McCarthy, J. J., and C. H. Smith. A Review of Ozone and Its Appli- 

cation to Domestic Wastewater Treatment. J. Am. Water Works 

Assoc., 66:718-725, 1974. 

203

58. 

59. 

60. 

61. 

62. 

63. 

64. 

65. 

66. 

67. 

68. 

Poynter, S. F., J. S. Slade, and H. H. Jones. The Disinfection of 

Water with Special Reference to Viruses. Water Treat. Exam., 

22: 194-208, 1973. 

Scaccia, C., and H. M. Rosen. Ozone Contacting: What is the 

Answer? Presented at the Symposium on Advanced Ozone Technology, 

International Ozone Institute, Toronto, Canada, November 1977. 

Venosa, A. D., M. C. Meckes, E. J. Opatken, and J. W. Evans. 

Comparative Efficiencies of Ozone Utilization and Microorganism 

Reduction in Different Ozone Contactors. In: Progress in 

Wastewater Disinfection Technology, EPA 600/9-79-m8, NTIS Report 

No. PB 299 338, MERL, Cincinnati, Ohio, 1979. pp. 141-161. 

Process Design Manual for Nitrogen Control. EPA 625/l-75-007, 

United States Environmental Protection Agency, Center for 

Environmental Research Information, Cincinnati, Ohio, October 1975. 

434 pp. 

Process Design Manual for Phosphorus Removal. EPA 625/l-76-001, 

United States Environmental Protection Agency, Center for 

Environmental Research Information, Cincinnati, Ohio, April 1976. 

Brandes, M. Accumulation Rate and Characteristics of Septic Tank 

Sludge and Septage. J. Water Pollut. Control Fed., 50:936-943, 

1978. 

Laak, R., and F. J. Crates. Sewage Treatment by Septic Tank. In: 

Proceedings of the Second Home Sewage Treatment Symposium, Chica=, 



Sikora, L. J., and D. R. Keeney. Laboratory Studies on Stimulation 

of Biological Denitrification. In: Proceedings of the National 

Home Sewage Disposal Symposium, mcago, Illinois, December 1975, 


1975. pp. 64-73. 

Andreoli, A., N. Bartilucci, R. Forgione, and R. Reynolds. Nitro- 

gen Demand in a Subsurface Disposal System. J. Water Pollut. Con- 

trol Fed., 51:841-854, 1979. 

Goronszy, M. C. Intermittent Operation of the Extended Aeration 

Process for Small Systems. J. Water Pollut. Control Fed., 51:274, 

1979. 

Clifford, D. A., and W. J. Weber, Jr. Multicomponent Ion Exchange: 

Nitrate Removal Process with Land Disposal Regenerant. Ind. Water 

Eng., 15~18-26, 1978. 

204

69. Beulow; R. W., K. L. Kropp, 3. Withered, and J. M. Symons. Nitrate 

Removal by Anion Exchange Resins. Water Supply Research Labora- 

tory, National Environmental Research Center, Cincinnati, Ohio, 

1974. 

70. Brandes, M. Effective Phosphorus Removal by Adding Alum to Septic 

Tank. J. Water Pollut. Control Fed., 49:2285-2296, 1977. 

71. Midkiff, W. S., and W. J. Weber, Jr. Operating Characteristics of 

Strong Based Anion Exchange Reactor. Proc. Ind. Waste Conf., 

25:593-604, 1970. 

72. Erickson, A. E., J. M. Tiedje, B. G. Ellis, and C. M. Hansen. A 

Barriered Landscape Water Renovation System for Removing Phosphate 

and Nitrogen from Liquid Feedlot Waste. In: Livestock Waste Man- 

agement Pollution Abatement; Proceedings 3 the International Sym- 

posium on Livestock Wastes, St. Joseph, Michigan, 1971. pp. 232- 

234. 

73. Ellis, B. G., and A. E. Erickson. Movement and Transformation of 

Various Phosphorus Compounds in Soils. Michigan Water Resources 

Commission, Lansing, 1969. 

74. Tofflemire, T. J., M. Chen, F. E. Van Alstyne, L. J. Hetling, and 

D. B. Aulenbach. Phosphate Removal by Sands and Soils. Research 

Unit Technical Paper 31, New York State Department of Environmental 

Conservation, Albany, 1973. 92 pp. 

75. Detweiler, J. C. Phosphorus Removal by Adsorption on Alumina as 

Applied to Small Scale Waste Treatment. M.S. Report. University 


205


CHAPTER 7 

DISPOSAL METHODS 

Under the proper conditions, wastewater may be safely disposed of onto 

the land, into surface waters, or evaporated into the atmosphere by a 

variety of methods. The most commonly used methods for disposal of 

wastewater from single dwellings and small clusters of dwellings may be 

divided into three groups: (1) subsurface soil absorption systems, (2) 

evaporation systems, and (3) treatment systems that discharge to surface 

waters. Within each of these groups, there are various designs that may 

be selected based upon the site factors encountered and the characteris- 

tics of the wastewater. In some cases, a site limitation may be over- 

come by employing flow reduction or wastewater segregation devices (see 

Chapter 6). Because of the broad range of possible alternatives, the 

selection of the most appropriate design can be difficult. The site 

factor versus system design matrix presented in Chapter 2 should be con- 

sulted to aid in this selection. 

Onsite disposal methods discussed in this chapter are: 

1. Subsurface soil absorption systems 

- trenches and beds 

- seepage pits 

- mounds 

- fills 

- artificially drained systems 

- electro-osmosis 

2. Evaporation systems 

- evapotranspiration and evapotranspiration-absorption 

- evaporation and evaporation-percolation ponds 

3. Treatment systems that.discharge to surface waters 

Performance data and design, construction, operation, and maintenance 

information are provided for each of these methods. 

206

7.2 Subsurface Soil Absorption 


Where site conditions are suitable, subsurface soil absorption is 

usually the best method of wastewater disposal for single dwellings 

because of its simplicity, stability, and low cost. Under the proper 

conditions, the soil is an excellent treatment medium and requires 

little wastewater pretreatment. Partially treated wastewater is 

discharged below ground surface where it is absorbed and treated by the 

soil as it percolates to the groundwater. Continuous application of 

wastewater causes a clogging mat to form at the infiltrative surface, 

which slows the movement of water into the soil. This can be beneficial 

because it helps to maintain unsaturated soil conditions below the 

clogging mat. Travel through two to four feet of unsaturated soil is 

necessary to provide adequate removals of pathogenic organisms and other 

pollutants from the wastewater before it reaches the groundwater. 

However, it can reduce the infiltration rate of soil substantially. 

Fortunately, the clogging mat seldom seals the soil completely. 

Therefore, if a subsurface soil absorption system is to have a long 

life, the design must be based on the infiltration rate through the 

clogging Mt. that ultimately forms. Formation of the clogging mat 

depends primarily on loading patterns, although other factors may impact 

its development. 

7.2.1.1 Types of Subsurface Soil Absorption Systems 

Several different designs of subsurface soil absorption systems may be 

used. They include trenches and beds, seepage pits, mounds, fills, and 

artificially drained systems. All are covered excavations filled with 

porous media with a means for introducing and distributing the waste- 

water throughout the system. The distribution system discharges the 

wastewater into the voids of the porous media. The voids maintain expo- 

sure of the soil's infiltrative surface and provide storage for the 

wastewater until it can seep away into the surrounding soil. 

These systems are usually used to treat and dispose of septic tank ef- 

fluent. While septic tank effluent rapidly forms a clogging mat in most 

soils, the clogging mat seems to reach an equilibrium condition through 

which the wastewater can flow at a reasonably constant rate, though it 

varies from soil to soil (l)(2)(3)(4). Improved pretreatment of the 

wastewater does not appear to reduce the intensity of clogging, except 

in coarse granular soils such as sands (4)(5)(6). 

207

7.2.1.2 System Selection 

The type of subsurface soil absorption system selected depends on the 

site characteristics encountered. Critical site factors include soil 

profile characteristics and. permeability, soil depth over water tables 

or bedrock, slope, and the size of the acceptable area. Where the soil 

is at least moderately permeable and remains unsaturated several feet 

below the system throughout the year, trenches or beds may be used. 

Trenches and beds are excavations of relatively large area1 extent that 

usually rely on the upper soil horizons to absorb the wastewater through 

the bottom and sidewalls of the excavation. Seepage pits are deep exca- 

vations designed primarily for lateral absorption of the wastewater 

through the sidewalls of the excavation; they are used only where the 

groundwater level is well below the bottom of the pit, and where beds 

and trenches are not feasible. 

Where the soils are relatively impermeable or remain saturated near the 

surface, other designs can be used to overcome some limitations. Mounds 

may be suitable where shallow bedrock, high water table, or slowly per- 

meable soil conditions exist. Mounds are beds constructed above the 

natural soil surface in a suitable fill material. Fill systems are 

trench or bed systems constructed in fill material brought in to replace 

unsuitable soils. Fills can be used to overcome some of the same limi- 

tations as mounds. Curtain or underdrain designs sometimes can be used 

to artifically lower groundwater tables beneath the absorption area so 

trenches or beds may be constructed. Table 2-l presents the general 

site conditions under which the various designs discussed in this manual 

are best suited. For specific site criteria appropriate for each, refer 

to the individual design sections in this chapter. 

7.2.2 Trench and Bed Systems 


Trench and bed systems are the most commonly used method for onsite 

wastewater treatment and disposal. Trenches are shallow, level excava- 

tions, usually 1 to 5 ft (0.3 to 1.5 m) deep and 1 to 3 ft (0.3 to 0.9 

m) wide. The bottom is filled with 6 in. (15 cm) or more of washed 

crushed rock or' 'gravel over which is laid a single line of perforated 

distribution piping. Additional rock is placed over the pipe and the 

rock covered with a suitable semipermeable barrier to prevent the back- 

fill from penetrating the rock. Both the bottoms and sidewalls of the 

trenches are infiltrative surfaces. Beds differ from trenches in that 

they are wider than 3 ft (0.9 m) and may contain more than one line of 

distribution piping (see Figures 7-1 and 7-2). Thus, the bottoms of the 

beds are the principal infiltrative surfaces. 

208

FIGURE 7-l 

TYPICAL TRENCH SYSTEM 

209 

Backfill 

3/4 - 2-l/2 in. Rock 

w Water Table or 

Creviced Bedrock

Distribution 

FIGURE 7-2 

TYPICAL BED SYSTEM 

amu J a 

k3-6 ft. A3-6 f1.J -1 t 6112 in. of 

I, P I 3/4-21/2 inct 1 

2-4 ft. rnii 

dia: Rock 

Water Table or 

Creviced Bedrock 

210

7.2.2.2 Application 

Site criteria for trench and bed systems are summarized in Table 7-1. 

They are based upon factors necessary to maintain reasonable infiltra- 

tion rates and adequate treatment performance over many years of con- 

tinuous service. Chapter 3 should be consulted for proper site eval- 

uation procedures. 

The wastewater entering the trench or bed should be nearly free from 

settleable solids, greases, and fats. Large quantities of these 

wastewater constituents hasten the clogging of the soil (9). The 

organic strength of the wastewater has not been well correlated with the 

clogging mat resistance except in granular soils (4)(5). Water softener 

wastes have not been found to be harmful to the system even when signi- 

ficant amounts of clay are present (9)(10). However, the use of water 

softeners can add a significant hydraulic load to the absorption system 

and should be taken into account. The normal use of other household 

chemicals and detergents have also been shown to have no ill effects on 

the system (9). 


a. Sizing the Infiltrative Surface 

The design of soil absorption systems begins at the infiltrative surface 

where the wastewater enters the soil. With continued application of 

wastewater, this surface clogs and the rate of wastewater infiltration 

is reduced below the percolative capacity of the surrounding soil. 

Therefore, the infiltrative surface must be sized on the basis of the 

expected hydraulic conductivity of the clogging mat and the estimated 

daily wastewater flow (see Chapter 41. 

Direct measurement of the expected wastewater infiltration rate through 

a mature clogging mat in a specific soil cannot be done prior to design. 

However, experience with operating subsurface soil absorption systems 

has shown that design loadings can sometimes be correlated with soil 

texture (31(4)(111(12). Recommended rates of application versus soil 

textures and percolation rates are presented in Table 7-2. This table 

is meant only as a guide. Soil texture and measured percolation rates 

will not always be correlated as indicated, due to differences in struc- 

ture, clay mineral content, bulk densities, and other factors in various 

areas of the country (see Chapter 3). 

211

TABLE 7-l 

SITE CRITERIA FOR TRENCH AND BED SYSTEMS 

I tern Criteria 

Landscape Positiona Level, well drained areas, crests of 

slopes, convex slopes most desirable. 

Avoid depressions, bases of slopes and 

concave slopes unless suitable surface 

drainage is provided. 

Slopea 

Typical Horizontal Separation 

Distancesb 

Soil 

Water Supply Wells 50 - 100 ft 

Surface Waters, Springs 50 - 100 ft 

Escarpments, Manmade Cuts 10 - 20 ft 

Boundary of Property 5 - 10 ft 

Building Foundations 10 - 20 ft 

Texture 

Structure 

Color 

0 to 25%. Slopes in excess of 25% can 

be utilized but the use of construction 

machinery may be limited (7). Bed 

systems are limited to 0 to 5%. 

Soils with sandy or loamy textures are 

best suited. Gravelly and cobbley 

soils with open pores and slowly 

permeable clay soils are less 

desirable. 

Strong granular, blocky or prismatic 

structures are desirable. Platy or 

unstructured massive soils should be 

avoided. 

Bright uniform colors indicate 

well-drained, well-aerated soils. 

Dull, gray or mottled soils indicate 

continuous or seasonal saturation and 

are unsuitable. 

212

Layering 

Unsaturated Depth 

Percolation Rate 

TABLE 7-l (continued) 

Item Criteria 

Soils exhibiting layers with distinct 

textural or structural changes should 

be carefully evaluated to insure water 

movement will not be severely 

restricted. 

2 to 4 ft of unsaturated soil should 

exist between the bottom of the system 

and the seasonally high water table or 

bedrock (3)(4)(8). 

l-60 min/in. (average of at least 3 

percolation tests1.c Systems can be 

constructed in soils with slower 

percolation rates, but soil damage 

during construction must be avoided. 

a Landscape position and slope are more restrictive for beds because 

of the depths of cut on the upslope side. 

b Intended only as a guide. Safe distance varies from site to site, 

based upon topography, soil permeability, ground water gradients, 

geology, etc. 

c Soils with percolation rates ~1 min/in. can be used for trenches and 

beds if the soil is replaced with a suitably thick (>2 ft) layer of 

loamy sand or sand. 

213

TABLE 7-2 

RECOMMENDED RATES OF WASTEWATER APPLICATION 

FOR TRENCH AND BED BOTTOM AREAS (4)(11)(12)a 

Soil Texture 

Gravel, coarse sand 

Coarse to medium sand 

Fine sand, loamy sand 

Sandy loam, loam 

Loam, porous silt loam 

Silty clay loam, clay loamd 

Percolation Application 

Rate Rateb 

min/in. gpd/ft2 

4 Not suitablec 

1 - 5 1.2 

6 - 15 0.8 

16 - 30 0.6 

31 - 60 0.45 

61 - 120 0.2e 

a May be suitable estimates for sidewall infiltration rates. 

b Rates based on septic tank effluent from a domestic waste 

source. A factor of safety may be desirable for wastes of 

significantly different character. 

c Soils with percolation rates (1 min/in. can be used if the 

soil is replaced with a suitably thick (>2 ft) layer of loamy 

sand or sand. 

d Soils without expandable clays. 

e These soils may be easily damaged during construction. 

214

Conventional trench or bed designs should not be used for rapidly perme- 

able soils with percolation rates faster than 1 min/in. (0.4 min/cm) 

(11). The rapidly permeable soils may not provide the necessary treat- 

ment to protect the groundwater quality. This problem may be overcome 

by replacing the native soil with a suitably thick (greater than 2 feet) 

layer of loamy sand or sand textured soil. With the liner in place, the 

design of the system can follow the design of conventional trenches and 

beds using an assumed percolation rate of 6 to 15 min/in. (2.4 to 5.9 

min/cm). 

Conventional trench or bed designs should also be avoided in soils with 

percolation rates slower than 60 min/in. (24 min/cm). These soils can 

be easily smeared and compacted during construction,reducing the soil's 

infiltration rate to as little as half the expected rate (12). Trench 

systems may be used in soils with percolation rates as slow as 120 

min/in (47 min/cm), but only if great care is exercised during construc- 

tion. Construction should proceed only when the soil is sufficiently 

dry to resist compaction and smearing during excavation, This point is 

reached when it crumbles when trying to roll a sample into a wire be- 

tween the palms of the hands. Trenches should be installed so that con- 

struction machinery need not drive over the infiltrative surface. A 4- 

to 6-in. (lo- to 15-cm) sand liner in the bottom of the trench may be 

used to protect the soil from compaction during placement of the aggre- 

gate and to expose infiltrative surface that would otherwise be covered 

by the aggregate (11)(13). 

b. Geometry of the Infiltrative Surface 

Sidewalls as Infiltrative Surfaces: Both the horizontal bottom area and 

the vertical sidewalls of trenches and beds can act as infiltrative surfaces. 

When a gravity-fed system is first put into service, the bottom 

area is the only infiltrative surface. However, after a period of 

wastewater application, the bottom can become sufficiently clogged to 

pond liquid above it, at which time the sidewalls become infiltrative 

surfaces as well. Because the hydraulic gradients and resistances of 

the clogging mats on the bottom and sidewalls are not likely to be the 

same, the infiltration rates may be different. The objective in design 

is to maximize the area of the surface expected to have the highest 

infiltration rate while assuring adequate treatment of wastewater and 

protection of the groundwater. 

Because the sidewall is a vertical surface, clogging may not be as se- 

vere as that which occurs at the bottom surface, due to several fac- 

tors: (1) suspended solids in the wastewater may not be a significant 

factor in sidewall clogging; (2) the rising and falling liquid levels in 

the system allow alternative wetting and drying of the sidewall while 

the bottom may remain continuously inundated; and (3) the clogging mat 

215

can slough off the sidewall. These factors tend to make the sidewall 

clogging less severe than the bottom surface. However, the hydraulic 

gradient across the sidewall mat is also less. At the bottom surface, 

gravity, the hydrostatic pressure of the ponded water above, and the 

matric potential of the soil below the mat contribute to the total 

hydraulic gradient. At the .sidewall, the gravity potential is zero, and 

the hydrostatic potential diminshes to zero at the liquid surface. Be- 

cause the matric potential varies with changing soil moisture condi- 

tions, it is difficult to predict which infiltrative surface will be 

more effective. 

In humid regions where percolating rainwater reduces the matric poten- 

tial along the sidewall, shallow trench systems are suggested (41. The 

bottom area is the principal infiltrative surface in these systems. 

Shallow trenches often are best because the upper soil horizons are usu- 

ally more permeable and greater evapotranspiration can occur. In dry 

climates, the sidewall area may be used to a greater extent. The bottom 

area may be reduced as the sidewall area is increased. Common practice 

is not to give credit to the first 6 in. (15 cm) of sidewall area mea- 

sured from the trench bottom, but any exposed sidewall above 6 in. (15 

cm1 may be used to reduce the bottom area (3)(11). The infiltration 

rates given in Table 7-2 may be used for sidewall areas. 

Trench versus Bed Design: Because beds usually require less total land 

area and are less costly to construct, they are often installed instead 

of trenches. However, trenches are generally more desirable than beds 

(4)(11)(12)(13)(14). Trenches can provide up to five times more side- 

wall area than do beds for identical bottom areas. Less damage is 

likely to occur to the soil during construction because the excavation 

equipment can straddle the trenches so it is not necessary to drive on 

the infiltrative surface. On sloping sites, trenches can follow the 

contours to maintain the infiltrative surfaces in the same soil horizon 

and keep excavation to a minimum. Beds may be acceptable where the site 

is relatively level and the soils are sands and loamy sands. 

Shallow versus Deep Absorption Systems: Shallow soil absorption systems 

offer several advantages over deep systems. Because of greater plant 

and animal activity and less clay due to eluviation, the upper soil ho- 

rizons are usually more permeable than the deeper subsoil. Also, the 

plant activity helps reduce the loading on the system during the growing 

season by transpiring significant amounts of liquid and removing some 

nitrogen and phosphorus from the waterwater. Construction delays due to 

wet soils are also reduced because the upper horizons dry more quickly. 

On the other hand, deep systems have advantages. Increased depths per- 

mit increased sidewall area exposure for the same amount of bottom area. 

They also permit a greater depth of liquid ponding which increases the 

216

hydraulic gradient across the infiltrative surface. In some instances 

deep systems can be used to reach more permeable soil horizons when thi 

proximity of groundwater tables do not preclude their use. 

Freezing of shallow absorption systems is not a problem if kept in con- 

tinuous operation (4)(11). Carefully constructed systems with 6 to 12 

in. (15 to 30 cm) of soil cover, which are in continuous operation, will 

not freeze even in areas where frost penetration may be as great as 5 ft 

(1.5 m) if the distribution pipe is gravel packed and header pipes insu- 

lated where it is necessary for them to pass under driveways or other 

areas usually cleared of snow. 

Alternating Systems: Dividing the soil absorption system into more than 

one field to allow alternate use of the individual fields over extended 

periods of time can extend the life of the absorption system. Alterna- 

ting operation of the fields permits part of the system to "rest" peri- 

odically so that the infiltrative surface can be rejuvenated naturally 

through biodegradation of the clogging mat (4)(11)(12)(13)(15)(16). The 

"resting" field also acts as a standby unit that can be put into immedi- 

ate service if a failure occurs in the other part of the system, This 

provides a period of time during which the failed field can be rehabili- 

tated or rebuilt without an unwanted discharge. 

Alternating systems commonly consist of two fields. Each field contains 

50 to 100% of the total required area for a single field. Common prac- 

tice is to switch fields on a semiannual or annual schedule by means of 

a diversion valve (see Figure 7-3 and Chapter 8). Though it has not yet 

been proven, such operation may permit a reduction in the total system 

size. In sandy soils with a shallow water table, the use of alternating 

beds may increase the chance of groundwater contamination because of the 

loss of treatment efficiency when the clogging mat is decomposed after 

resting. 

c. Layout of the System 

Location: Locating the area for the soil absorption system should be 

done with care. On undeveloped lots, the site should be located prior 

to locating the house, well, drives, etc., to ensure the best area is 

reserved. The following recommendations should be considered when 

locating the soil absorption system: 

1. Locate the system where the surface drainage is good. Avoid 

depressions and bases of slopes and areas in the path of runoff 

from roofs, patios, driveways, or other paved areas unless sur- 

face drainage is provided. 

217

FIGURE 7-3 

ALTERNATING TRENCH SYSTEM WITH DIVERSION VALVE 

2. In areas with severe winters, avoid areas that are kept clear 

of snow. Automobiles, snowmobiles, and other vehicles should 

not be allowed on the area. Compacted or cleared snow will 

allow frost to penetrate the system, and compacted soil and 

loss of vegetation from traffic over the system will reduce 

evapotranspiration in the summer. 

3. Preserve as many trees as possible. Trenches may be run be- 

tween trees. Avoid damaging the trees during construction. 

Confi;urationfz Trenches should be used wherever possible. Not only do 

trenc es per arm better than beds, but they also conform to the site 

more easily. Trenches do not need to be straight, but should be curved 

to fit the contour of the lot or to avoid trees. A multi-trench system 

is preferable to a single trench because of the flexibility it offers in 

wastewater application. 

On lots with insufficient area for trenches or on sites with granular 

soils, beds may be used. If only a sloping site exists, the bed should 

be constructed with long axes following the contour. However, beds 

should not be constructed on sites with slopes greater than 10% because 

the excavation becomes too deep on the upslope side. In such instances, 

218

deep trenches with a greater depth of rock below the distribution pipe 

to increase the sidewall area is more suitable. 

Reserve Area: When planning and locating the absorption system, consid- 

eration should be given to reserving a suitable area for construction of 

a second system. The second system would be added if the first were to 

fail or if the system required expansion due to increased wastewater 

flows. Care must be used in constructing the second system so that the 

original system is not damaged by the construction equipment. 

The reserve area should be located to facilitate simultaneous or alter- 

nating loading of both systems. If the reserve area is used because the 

initial system has failed, the failing system should not be permanently 

abandoned. With time, the initial system will be naturally rejuvenated 

and can be used alternately with the reserve system. Reserve areas can 

be provided very easily with trench systems by reserving sufficient area 

between the initial trenches as shown in Figure 7-4. 

Dimensions: The absorption system should be dimensioned to best fit the 

lot while maintaining separation distances and avoiding excessive depths 

of excavation. Commonly used dimensions are given in Table 7-3. 

The depth of excavation is determined by the location of the most perme- 

able soil horizon and flow restricting layers or the high water table 

elevation. Unless a deep, more permeable horizon exists, the trench or 

bed bottom elevation should be maintained at about 18 to 24 in. (46 to 

61 cm) below the natural ground surface. To prevent freezing in cold 

climates, 6 to 12 in. (15 to 30 cm) of cover should be backfilled over 

the aggregate (11). 

If the water table or a very slowly permeable layer is too near the 

ground surface to construct the system at this depth, the system can be 

raised. Very shallow trenches 6 to 12 in. (15 to 30 cm) deep can be in- 

stalled and the area backfilled with additional soil (see Figure 7-5). 

Adequate separation distance must be provided between the trench bottom 

and the seasonally high groundwater level to prevent groundwater 

contamination. 

The length of the trench or bed system depends on the site characteris- 

tics. The length of the distribution laterals is commonly restricted to 

100 ft (30 m). This is based on the fears of root penetration, uneven 

settling, or pipe breakage which could disrupt the flow down the pipe to 

render the remaining downstream length useless. However, these fears 

are unwarranted because the aggregate transmits the wastewater (4)(13) 

(17). To assure adequate transmission and distribution of the 

219

FIGURE 7-4 

PROVISION OF A RESERVE AREA BETWEEN TRENCHES 

OF THE INITIAL SYSTEM ON A SLOPING SITE 

Reserve 

220 

From 

Pretryatment 

d-Drop Box

wastewater through the aggregate, extreme care must be taken to con- 

struct the trench bottom at the same elevation throughout its length. 

The overriding considerations for determining trench or bed lengths are 

the site characteristics. 

Spacing between trench sidewalls could be as little as 18 in. (46 cm). 

A spacing of 6 ft (1.8 m) is suggested, however, to facilitate con- 

struction and to provide a reserve area between trenches. 

TABLE 7-3 

TYPICAL DIMENSIONS FOR TRENCHES AND BEDS 

Bottom Cover 

System Width Lengthb Depthc Thickness Spacingd 

Tft ft in. ft 

Trenches i-3a 100 1.5-2.0 6 (min) 6 

Beds >3 100 1.5-2.0 6 (min) 6 

a Excavations generally should not be less than 1 ft wide 

because the sidewall may slough and infiltrate the aggregate(l0) 

b Length of lateral from distribution inlet manifold. May be 

greater if site characteristics demand. 

c May be deeper if a more suitable horizon exists at greater 

depth and sufficient depth can be maintained between the bottom 

and seasonably high water table. 

d From sidewall to sidewall. Trench spacing may be decreased 

because of soil flow net patterns, specifically for shallow 

trenches in sandy soils. 

221

FIGURE 7-5 

TRENCH SYSTEM INSTALLED TO OVERCOME A SHALLOW WATER 

TABLE 0~ RESTRICTIVE LAYER [AFTER (ii)] 

Diversion for 

Surface Water 

---- 

-- 

Seasonally High WaterTable - 

or Flow R&tr&ive Layer 

_f 

d. Effluent Distribution 

-- -------- 

Ground 

Surface 

Methods of Application: To ensure that the absorption system performs 

satisfactorily over a reasonably long lifetime, the method of wastewater 

application to the infiltrative surface must be compatible with the ex- 

isting soil and site characteristics. Methods of wastewater application 

can be grouped into three categories: (1) gravity flow; (2) dosing; and 

(3) uniform application. For designs of distribution networks employing 

these methods, see Section 7.2.8) 

1. Gravity flow is the simplest and most commonly employed of the 

distribution methods. Wastewater is allowed to flow into the 

absorption system directly from the treatment unit. With time, 

a clogging mat usually develops on the bottom surface of the 

absorption system and continuous ponding of the wastewater 

results. This may lead to more severe clogging of the soil, 

reducing the infiltration rate. However, this effect may be 

offset by the greater effective infiltrative area provided by 

submerging the sidewalls of the system, particularly in trench 

systems. The ponding also increases the hydraulic gradient 

222

across the clogging mat, which can increase the infiltration 

rate (2)(18). 

If adequate treatment is to be achieved in coarse granular 

soils such as sands, wastewater application by gravity flow 

requires that a clogging mat exist at the infiltrative surfaces 

to prevent saturated conditions in the underlying soil and to 

prevent groundwater contamination. The mat develops with con- 

tinued application, but groundwater contamination by pathogenic 

organisms and viruses can be a danger at first. 

2. Dosing can be employed to provide intermittent aeration of the 

infiltrative surface. In this method, periods of loading are 

followed by periods of resting, with cycle frequencies ranging 

from hours to days. The resting phase should be sufficiently 

long to allow the system to drain and expose the infiltrative 

surface to air, which encourages rapid degradation of the clog- 

ging materials by aerobic bacteria. 

This method of operation may increase the rate of infiltration, 

as well as extend the life of the absorption system, because 

the clogging mat resistance is reduced (1)(4)(6)(15)(17). In 

sands or coarser textured materials, the rapid infiltration 

rates can lead to bacterial and viral contamination of shallow 

groundwater, expecially when first put into use (4). There- 

fore, systems constructed in these soils should be dosed with 

small volumes of wastewater several times a day to prevent 

large saturated fronts moving through the soil. In finer tex- 

tured soils, absorption, rather than treatment, is the con- 

cern. Large, less frequent doses are more suitable in these 

soils to provide longer aeration times between doses (4). See 

Table 7-4 for suggested dosing frequencies. 

3. Uniform Application means applying the wastewater in doses uni- 

formly over the entire bottom area of the system to minimize 

local-overloading and the depth of ponding fol-lowing each dose. 

This is usually achieved with a pressure distribution network. 

In this manner, the soil is more likely to remain unsaturated 

even during initial start-up when no clogging mat is present. 

The minimum depths of ponding during application permit rapid 

draining and maximum exposure of the bottom surface to air 

which reduces the clogging mat resistance. The sidewall is 

lost as an infiltrative surface, but this may be compensated 

for by the maintenance of higher infiltration rates through the 

bottom surface. See Table 7-4 for suggested dosing frequen- 

cies. 

223

TABLE 7-4 

DOSING FREQUENCIES FOR VARIOUS SOIL TEXTURES 

Soil Texture Dosing Frequency 

Sand 


Loam 

Silt Loam 

Silty Clay Loam 

Clay 

4 Doses/Day 

1 Dose/Day 

Frequency Not Criticala 

1 Dose/Days 

Frequency Not Criticala 

a Long-term resting provided by alternating fields may be 

desirable. 

Selection of Application Method: The selection of an appropriate method 

of wastewater appllcatlon depends on whether improved absorption or 

improved treatment is the objective. This is determined by the soil 

permeability and the geometry of the infiltrative surface. Under some 

conditions, the method of application is not critical, so selection is 

based on simplicity of design, operation, and cost. Methods of appli- 

cation for various soil and site conditions are summarized in Table 7- 

5. Where more than one may be appropriate, the methods are listed in 

order of preference. 

e. Porous Media 

The function of the porous media placed below and around the distribu- 

tion pipe is four-fold. Its primary purposes are to support the dis- 

tribution pipe and to provide a media through which the wastewater can 

flow from the distribution pipe to reach the bottom and sidewall infil- 

tration areas. A second function is to provide storage of peak waste- 

water flows. Third, the media dissipates any energy that the incoming 

wastewater may have which could erode the infiltrative surface. 

Finally, the media supports the sidewall of the excavation to prevent 

its collapse. 

224

TABLE 7-5 

METHODS OF WASTEWATER APPLICATION FOR VARIOUS SYSTEM DESIGNS 

AND SOIL PERMEABILITIESa 

Soil 

Permeability 

(Percolation Rate) 

Very Rapid 

1x1 min/in.) 

Rapid 

(l-10 min/in.) 

Moderate 

(11-60 min/in.) 

Slow 

(~60 min/in.) 

Trenches or Beds 

(Fills, Drains) 

On Level Site 

Uniform Applicationb 

Dosing 

Uniform Application 

Dosing 

Gravity 

Dosing 

Gravity 

Uniform Application 

Not Critical 

a Methods of application are listed in order of preference. 

Trenches (Drains) 

On Sloping 

Site (>5%) 

Gravity 

Dosing 

Gravity 

Dosing 

Gravity 

Dosing 

Not Critical 

b Should be used in alternating field systems to ensure adequate 

treatment. 

225

The depth of the porous media may vary. A.minimum of 6 in. (15 cm) 

below the distribution pipe invert and 2 in. (5 cm) above the crown of 

the pipe is suggested. Greater depths may be used to increase the 

sidewall area and to increase the hydraulic head on the infiltrative 

surface. 

Gravel or crushed rock is usually used as the porous media, though other 

durable porous materials may be suitable. The suggested gravel or rock 

size is 3/4 to 2-l/2 in. (1.8 to 6.4 cm) in diameter. Smaller sizes are 

preferred because masking of the infiltrative surface by the rock is 

reduced (13). The rock should be durable and resistant to slaking and 

dissolution. A hardness of 3 or greater on the Mob's Scale of Hardness 

is suggested. Rock that can scratch a copper penny without leaving any 

residual rock meets this criterion. Crushed limestone is unsuitable 

unless dolomitic. The media should be washed to remove all fines that 

could clog the infiltrative surface. 

To maintain the porous nature of the media, the media must be covered 

with a material to prevent backfilled soil from entering the media and 

filling the voids. Treated building paper was once used but has been 

abandoned in favor of untreated building paper, synthetic drainage fab- 

ric, marsh hay or straw. These materials do not create a vapor barrier 

and permit some moisture to pass through to the soil above where it can 

be removed through evapotranspiration. All these materials, except for 

the drainage fabric, will eventually decay. If they decay before the 

soil has stabilized, the value of the materials is lost. To ensure the 

barrier is not lost prematurely, heavy duty building paper of 40 to 60 

lb (18 to 27 kg) weight or a 4 to 6 in. (10 to 15 cm) layer of marsh hay 

or straw should be used. In dry sandy soils, a 4 in. (10 cm) layer of 

hay or straw covered with untreated building paper is suggested to pre- 

vent the backfill from filtering down into the rock. 

f. Inspection Pipes 

Inspection pipes located in the subsurface soil absorption system pro- 

vide limited access to observe the depth of ponding, a measure of the 

performance of the system, and a means of locating the subsurface field. 

If used, the inspection pipes should extend from the bottom infiltrative 

surface of the system up to or above final grade. The bottom should be 

open and the top capped. The portion of the pipe within the gravel 

should be perforated to permit a free flow of water (see Figure 7-6). 

226

7.2.2.4 Construction 

A frequent cause of early failure of soil absorption systems is the use 

of poor construction techniques. The following should be considered for 

construction of a soil absorption system: 

a. Layout 

The system should be laid out to facilitate the maneuvering of construc- 

tion equipment so that damage to the soil is minimized. 

1. Absorption system area should be staked out and roped off 

immediately after the site evaluation to keep construction 

equipment and other vehicles off the area until construction of 

the system begins. 

2. Trenches rather than beds are preferable in soils with signifi- 

cant clay content (greater than 25% by weight1 because equip- 

ment can straddle the trenches. This reduces the compaction 

and smearing at the exposed infiltrative surface. 

3. Trenches should be spaced at least 6 ft (1.8 m) apart to facil- 

itate the operation of the construction equipment if there is 

sufficient area. 

4. To minimize sidewall compaction, trench widths should be made 

larger than the bucket used for excavation. Buckets are made 

to compact the sidewall to prevent caving during excavation. 

If the excavation is wider than the bucket, this effect is min- 

imized. An alternative is to use modified buckets with side 

cutters or raker teeth (see Figure 7-7). 

5. Trenches should follow the contour and be placed outside the 

drip lines of trees to avoid root damage. 

b. Excavation 

Absorption of waste effluent by soil requires that the soil pores remain 

open at the infiltrative surface. If these are sealed during construction 

by compaction, smearing, or puddling of the soil, the system may be 

rendered useless. The tendency toward compaction, smearing, and puddling 

depends upon the soil type, moisture content, and applied force. 

227

Distr 

Pipe, 

FIGURE 7-6 

TYPICAL INSPECTION PIPE 

Vent Cap, 

FIGURE 7-7 

.Backfill 

4” Perforated 

Inspection Pipe 

t- Open Bottom 

BACKHOE BUCKET WITH REMOVABLE RAKER TEETH (11) 

228 

in. Rods or Bolts 

pproximately 1 -l/2 in. 

Spaced Approximately 

Long 

3 in. on

Soils with high clay contents (greater than 25% by weight) are very 

susceptible to damage, while sands are rarely affected. Careful con- 

struction techniques minimize this soil damage. They include: 

1. 

2. 

3. 

4. 

5. 

6. 

Excavation may proceed in clayey soils only when the moisture 

content is below the soil's plastic limit. If a sample of soil 

taken at the depth of the proposed bottom of the system forms a 

" wi re" instead of crumbling when attempting to roll it between 

the hands, the soil is too wet. 

A backhoe is usually used to excavate the system. Front-end 

loaders or bulldozer blades should not be used because the 

scraping action of the bucket or blade can smear the soil se- 

verely, and the wheels or tracks compact the exposed 

infiltrative surface. 

Excavation equipment must not be driven on the bottom of the 

system. If trenches are used, the equipment can straddle the 

excavation. If a bed is used, the bed should be divided into 

segments so the machinery can always operate from undisturbed 

soil. 

The bottom of each trench or bed must be level throughout to 

ensure more uniform distribution of effluent. A level and tri- 

pod are essential equipment. 

The bottom and sidewalls of the excavation should be left with 

a rough open surface. Any smeared and compacted surfaces 

should be removed with care. 

Work should be scheduled only when the infiltrative surface can 

be covered in one day, because wind-blown silt or raindrop im- 

pact can clog the soil. 

c. Backfilling 

Once the infiltrative surface 

operations must be done careful 

is properly prepared, the backfilling 

ly to avoid any damage to the soil. 

1. The gravel or crushed rock used as the porous media is laid in 

by a backhoe or front-end loader rather than dumped in by 

truck. This should be done from the sides of the system rather 

than driving out onto the exposed bottom. In large beds, the 

gravel or rock should be pushed out ahead of a small bulldozer. 

2. The distribution pipes are covered with a minimum of 2 in. (5 

cm) of gravel or rock to retard root growth, to insulate 

229

against freezing and to stabilize .the pipe before backfill- 

ing. Procedures for constructing the distribution network are 

discussed in Section 7.2.8. 

3. The gravel or rock is covered with untreated building paper, 

synthetic drainage fabric, marsh hay or straw to prevent the 

unconsolidated soil cover from entering the media. The media 

should be covered completely. If untreated building paper is 

used, the seams should overlap at least 2 in. (5 cm) and any 

tears covered. If marsh hay or straw is used, it should be 

spread uniformly to a depth of 4 to 6 in. (10 to 15 cm). In 

bed construction, spreading a layer of hay or straw covered 

with untreated building paper is good practice. 

4. The backfill material should be similar to the natural soil and 

no more permeable. It should be mounded above natural grade to 

allow for settling and to channel runoff away from the system. 


a. Routine Maintenance 

Once installed, a subsurface soil absorption system requires little or 

no attention as long as the wastewater discharged into it is nearly free 

of settleable solids, greases, fats, and oils. This requires that the 

pretreatment unit be maintained (see Chapter 6). To provide added in- 

surance that the system will have a long, useful life, the following 

actions are suggested: 

1. Resting of the system by taking it out of service for a period 

of time is an effective method of restoring the infiltration 

rate. Resting allows the absorption field to gradually drain, 

exposing the infiltrative surfaces to air. After several 

months, the clogging mat is degraded through biochemical and 

physical processes (1)(4)(6)(13)(15). This requires that a 

second absorption system exist to allow continued disposal, 

while the first is in the resting phase. The systems can be 

alternated on a yearly basis by means of a diversion valve (see 

Figure 7-3). 

2. The plumbing fixtures in the home should be checked regularly 

to repair any leaks which can add substantial amounts of water 

to the system. 

3. The use of special additives such as yeast, bacteria, chemi- 

cals, and enzyme preparations is not necessary and is of 

230

little value for the proper function of the soil absorption 

system (3)(4). 

4. Periodic application of oxidizing agents, particularly hydrogen 

peroxide, are being tried as a preventative maintenance proce- 

dure (19). If properly applied, the agents oxidize the clog- 

ging mat to restore much of the system's infiltration capacity 

within a day or two. Handling of these agents is very danger- 

OUS) and therefore the treatment should be done by trained 

individuals only. Experience with this treatment has been 

insufficient to determine its long-term effectiveness in a 

variety of soil types. 

b. Rehabilitation 

Occasionally, soil absorption systems fail, necessitating their reha- 

bilitation. The causes of failure can be complex, resulting from poor 

siting, poor design, poor construction, poor maintenance, hydraulic 

overloading, or a combination of these. To determine the most approp- 

riate method of rehabilitation, the cause of failure must be determined. 

Figure 7-8 suggests ways to determine the cause of failure and corres- 

ponding ways of rehabilitating the system. 

The failure frequency should be determined before isolating the cause. 

Failure may occur occasionally or continuously. Occasional failure man- 

ifests itself with occasional seepage on the ground surface, sluggish 

drains, or plumbing backups. These usually coincide with periods of 

heavy rainfall or snomelt. Continuous failure can have the same symp- 

toms but on a continuous basis. However, some systems may seriously 

contaminate the groundwater with no surface manifestations of failure. 

These failures are detected by groundwater sampling. 

Occasional Failure: The cause of, occasional failure is much easier to 

determine, and rehabilitation can be more simple. Since the system 

functions between periods of failure, sizing and construction usually 

can be eliminated as the cause. In these instances, failure is the 

result of poor siting, poor maintenance, or hydraulic overloading. 

Excessive water use, plumbing leaks, or foundation drain discharges are 

common reasons for hydraulic overloading. These can be corrected by the 

appropriate action as indicated in Figure 7-8. 

The next step is to investigate the site of the absorption system. 

Occasional failure usually is due to poor drainage or seasonally high 

water table conditions. The surface grading and landscape position 

should be checked for poor surface drainage conditions. Local soil 

conditions should also be investigated by borings for seasonally high 

231

Pertodic 

Deternvne Cause 

u O&loading 

Check: 

l Landscape 

Position 

l Surlace Gradmg 

l Depth to High 

Groundwater 

l Neighboring Systems 

Condtttons 

I 

Correctwe Actions _ 

. Drammg 

. Regradmg/Filling 

. Holding Tank (when 

necessaryI 

. Reconstruction 

Check: 

l Ptumbmg 

FIGURE 7-8 

METHODS OF SOIL ABSORPTION FIELD REHABILITATION 

l Excessive Water 

Use 

l Foundation Drawn 

Discharge 

I 

Correctwe Actlow. 

. Repair Plumbmg 

. Flow Reductton 

. Elimmata Clear 

Water Discharges 

Majntenance 

Check. 

l Mamtenance 

Record 

l Condltmn of 


Ullll 

Correctwe Acuons 

. Pumping 

l Reoair 

Failure Noted 

Determine FailureFrequency 

Withln 1 Year 

Determine Cause 

Sttmg/ 

Design/ 

Constr”ctlon 

Check: 

l So11 Type (Tex- 

ture tiydrauhc 

Conductwtv) 

‘= Unsaturaled 

Depth of Soil 

l Landscape 

Positlon 

l system Sire 

(Tank and Field) 

l Dlstrlbutmn of 

Effluent 

l Inllltratlon Rate 

l Nwghbonng SYS- 

tems Condltlons 

Correctwe Actions 

. DosIng 

. Addltwn 

. Reconstruct 

CO”V~“llO”~l 

Alternate 

Holdmg Tank 

CO”“““O”S 

I 

Determine Age of System When 

Fadure First Occurred 

Overloadma 

Check. 

l Plumbmg 

l System Laadtng 

l Waste Character- 

isucs 

I 

. Repa” Plumbmg 

. Flow Reduction 

. Ehmmate Clear 

Water Discharges 

. Waste Segregation 

. Improved Pretreatment 

After l-Yea1 

Determine Cause 

Mamtenancc 

Check: 

l Mamtenance Record 

l Condltlon of lank 

* Condillon of Field 

l SYstem Age 

. Building Lateral 

I 

Corrective Actions 

. Pumping 

. Hydrogen PeroxIde 

. mstmg

water tables (see Chapter 3). Corrective actions include improving 

surface drainage by regrading or filling low areas. High water table 

conditions may be corrected in some instances by installing drains (see 

Section 7.2.6). 

Lack of maintenance of the treatment unit preceding 

field may also be a cause of occasional failure. 

point of infiltration and inflow during wet periods. 

pumped and leaks repaired. 

the soil absorption 

The unit may be a 

The unit should be 

Continuous Failure: The causes of.continuous failure are more difficult 

to determine. However, learning the age of the system when failure 

first occurred is very useful in isolating the cause. 

If failure occurred within the first year of operation, the cause is 

probably due to poor siting, design, or construction. It is useful to 

check the performance of neighboring systems installed in similar 

soils. If they have similar loading rates and are working well, the 

failing system should be checked for proper sizing. A small system can 

be enlarged by adding new infiltration areas. In some instances, the 

sizing may be adequate but the distribution of the wastewater is poor 

due to improper construction. Providing dosing may correct this problem 

(see Section 7.2.8). Damage to the soil during construction may also 

cause failure, in which case the infiltrative area is less effective. 

Reconstruction or an addition is necessary. Alternate systems should be 

considered if the site is poor. This includes investigating the fea- 

sibility of a cluster or community system if surrounding systems are 

experiencing similar problems. 

If the system had many years of useful service before failure occurred, 

hydraulic overloading or poor maintenance is usually the cause. The 

first step is to find out as much about the system as possible. A 

sketch of the system showing the size, configuration, and location 

should be made. A soil profile description should also be obtained. 

These items may be on file at the local regulatory agency but their ac- 

curacy should be confirmed by an onsite visit. If the system provided 

several years of useful service, evidences of overloading should be 

investigated first. Wastewater volume and characteristics (solids, 

greases, fats, oil) should be determined. Overloading may be corrected 

by repairing plumbing, installing flow reduction fixtures (see Chapter 

51, and eliminating any discharges from foundation drains. If the vol- 

ume reductions are insufficient for acceptance by the existing infiltra- 

tive surface, then additional infiltrative areas must be constructed. 

Systems serving commercial buildings may fail because of the'wastewater 

characteristics. High solids concentrations or large amounts of fats, 

233

oils, and greases, can cause failure. This is. particularly true of sys- 

tems serving restaurants and laundromats. These failures can be correc- 

ted by segregating the wastewaters to eliminate the troublesome waste- 

waters (see Chapter 51, or by improving pretreatment (see Chapter 6). 

Lack of proper maintenance of the treatment unit may have resulted in 

excessive clogging due to poor solids removal by the unit. This can be 

determined by checking the maintenance record and the condition of the 

unit. If this appears to be the problem, the unit should be pumped and 

repaired, or replaced if necessary. The infiltrative surface of the ab- 

sorption field should also be checked. If siting, design, or mainten- 

ance do not appear to be the cause of failure, excessive clogging is 

probably the problem. In such cases, the infiltrative surface can some- 

times be rejuvenated by oxidizing the clogging mat (4)(9)(13)(16). This 

can be done by allowing the system to drain and rest for several months 

(4). To permit resting, a new system must be constructed with means 

provided for switching back and forth. Alternatively, the septic tank 

could be operated as a holding tank until the clogging mat has been 

oxidized. However, this involves frequent pumping, which may be costly. 

Another method, still in the experimental stage, is the use of the 

chemical oxidant, hydrogen peroxide (16). Because it is new, it is not 

known if it will work well in all soils. Extreme care should be used in 

its application because it is a strong oxidizing agent. Only individu- 

als trained in its use should perform the treatment. 

7.2.2.6 Considerations for Multi-Home and Commercial 

Wastewaters 

Design of trench and bed soil absorption systems for small institutions, 

commercial establishments, and clusters of dwellings generally follows 

the same design principles as for single dwellings. In cluster systems 

serving more than about five homes, however, peak flow estimates can be 

reduced because of flow attenuation, but contributions from infiltration 

through the collection system must be included. Peak flow estimates 

should be based on the total number of people to be served (see Chapter 

4). Rates of infiltration will vary with the type of collection sewer 

used (191(20). 

With commercial flows, the character of the wastewater is an important 

consideration. Proper pretreatment is necessary if the character is 

significantly different than domestic wastewater. 

Flexibility in operation should also be incorporated into systems serv- 

ing larger flows since a failure can create a significant problem. Al- 

ternating bed systems should be considered. A three-field system can be 

constructed in which each field contains 50% of the required absorption 

234

area (19). This design allows flexibility in operation. Two beds are 

always in operation, providing 100% of the needed i-nfiltrative surface. 

The third field is alternated in service on a semi annual or annual 

schedule. Thus, each field is in service for one or two years and 

"rested" for 6 months to one year to rejuvenate. The third field also 

acts as a standby unit in case one field fails. The idle field can be 

put into service immediately while a failed field is rehabilitated. 

Larger systems should utilize some dosing or uniform application to 

assure proper performance. 

7.2.3 Seepage Pits 


Seepage pits or dry wells are deep excavations used for subsurface dis- 

posal of pretreated wastewater. Covered porous-walled chambers are 

placed in the excavation and surrounded by gravel or crushed rock (see 

Figure 7-9). Wastewater enters the chamber where it is stored until it 

seeps out through the chamber wall and infiltrates the sidewall of the 

excavation. 

Seepage pits are generally discouraged by many local regulatory agencies 

in favor of trench or bed systems. However, seepage pits have been 

shown to be an acceptable method of disposal for small wastewater flows 

(21). Seepage pits are used where land area is too limited for trench 

or bed systems; and either the groundwater level is deep at all times, 

or the upper 3 to 4 ft (0.9 to 1.2 m) of the soil profile is underlain 

by a more permeable unsaturated soil material of great depth. 

7.2.3.2 Site Considerations 

The suggested site criteria for seepage pits are similar to those for 

trench and bed systems summarized in Table 7-l except that soils with 

percolation rates slower than 30 min/in. (12 min/cm) are generally ex- 

cluded. In addition, since the excavation sidewall is used as the 

infiltrative surface, percolation tests are run ineach soil layer en- 

counted. Maintaining sufficient separation between the bottom of the 

seepage pit and the high water table is a particularly important con- 

sideration for protection of groundwater quality. 

235

4" Inspection Pip 

FIGURE 7-9 

SEEPAGE PIT CROSS SECTION 

te Cover 

xtendedto Solid Earth 

Brick, Block, Ring, or 

Precast Chamber 

with Open Joints 

4' min. Unsaturated Soil. 

Water Table 

ImperviousLayer 

1 -7-e-m 


a. Sizing the Infiltrative Surface 

Since the dominant infiltration surface of a seepage pit is the side- 

wall, the depth and diameter of the pit is determined from the perco- 

lation rate and thickness of each soil layer exposed by the excavation. 

A weighted average of the percolation test results (sum of thickness 

times percolation rate of each layer divided by the total thickness) is 

used. Soil lay&s with percolation rates slower than 30 min/in. (12 

min/cm) are excluded from this computation (3). 

The weighted percolation rate is used to determine the required sidewall 

area. Infiltration rates presented previously in Table 7-2 are used 

with the estimated daily wastewater flow to compute the necessary 

sidewall area. 

236

Table 7-6 can be used to determine the necessary seepage pit sidewall 

area for various effective depths below the seepage pit inlet. 

TABLE 7-6 

SIDEWALL AREAS OF CIRCULAR SEEPAGE PITS (ft2ja 

Seepageb 

Pit Thickness of Effective Layers Below Inlet (ft) 

Diameter 1 2 3 4 5 6 I 8 9 10 

T----------- 

1 

2 

3 

4 

5 

6 

7 

8 

1: 

11 

12 

3.1 

6.3 

129.: 

15:7 

18.8 

22.0 

25.1 

28.3 

31.4 

34.6 

37.7 

136 1; :z :F! :; 4242 50 25 :; 63 31 

19 

25 

31 

:: 

47 

5”: 

63 

47 

63 

79 

7”: 

94 

868” 10’: 

110 126 

$35 

141 

94 

126 

157 

38 

44 

50 

57 

66 

75 

ii 

101 

94 

110 

126 

113 

132 

151 

132 

154 

176 

151 

176 

201 

170 

198 

226 

188 

220 

251 

57 

63 

69 

85 

94 

104 

113 

126 

138 

141 

157 

173 

170 

188 

207 

198 

220 

242 

226 

251 

276 

254 

283 

311 

283 

314 

346 

75 113 151 188 226 264 302 339 377 

a Areas for greater depths can be found by adding columns. For 

example, the area of a 5 ft diameter pit, 15 ft deep is equal to 

157 + 79, or 236 ft. 

b Diameter of excavation. 

b. System Layout 

Seepage pits may be any diameter or depth provided they are structurally 

sound and can be constructed without seriously damaging the soil. Typi- 

cally, seepage pits are 6 to 12 ft (1.8 to 3.6 m) in diameter and 10 to 

20 ft (3 to 6 m) deep but pits 18 in. (0.5 m) in diameter and 40 ft (12 

m) deep have been constructed (22). When more than one pit is required, 

experience has shown that a separation distance from sidewall to side- 

wall equal to 3 times the diameter of the largest pit should be main- 

tained (3). 

237

The same guidelines used in locating trenches, and beds are used to lo- 

cate seepage pits. Area should be reserved for additional pits if 

necessary. 


Pits may be dug with conventional excavating equipment or with power 

augers. Particular care must be exercised to ensure that the soils are 

not too wet before starting construction. If powered bucket augers are 

used, the pits should be reamed to a larger diameter than the bucket to 

minimize compaction and smearing of the soil. Power screw augers should 

only be used in granular soils because smearing of the sidewall is dif- 

ficult to prevent with such equipment. 

To maximize wastewater storage, porous walled chambers without bottoms 

are usually used. Precast concrete seepage chambers may be used or the 

chambers may be constructed out of clay or concrete brick, block or 

rings. The rings must have notches in them to provide for seepage. 

Brick or block are laid without mortar, with staggered open joints. 

Hollow block may be laid on its side but a 4-in. (lo-cm) wall thickness 

should be maintained. Large-diameter perforated pipe standing on end 

can be used in small diameter pits. Six to 12 in. (15 to 30 cm) of 

clean gravel or 3/4 to 2-l/2 in. (1.8 to 6.4 cm) crushed rock is placed 

at the bottom of the excavation prior to placement or construction of 

the chamber. This provides a firm foundation for the chamber and 

prevents bottom soil from being removed if the pit is pumped. 

The chamber is constructed one to two feet smaller in diameter than the 

excavation. The annular space left between the wall of the chamber and 

the excavation is filled with clean gravel or crushed rock to the top of 

the chamber. 

Covers of suitable strength to support the soil cover and any antici- 

pated loads are placed over the chamber and extend at least 12 in. 

beyond the excavation. Access to the pit for inspection purposes can be 

provided by a manhole. If a manhole is used, it should be covered with 

6 to 12 in. (15 to 30 cm) of soil. An inspection pipe can extend to 

ground surface. A noncorrosive, watertight cap should be used with the 

inspection pipe. 

233

7.2.3.5 Maintenance 

A well-designed and constructed seepage pit requires no routine mainte- 

nance. However, failure ocassionally occurs. Pumping and resting is 

the only reasonable rehabilitation technique available. 

7.2.4 Mound Systems 


The mound system was originally developed in North Dakota in the late 

1940's where it became known as the NODAK disposal system (23). The 

mound was designed to overcome problems with slowly permeable soils and 

high water tables in rural areas. The absorption bed was constructed in 

coarse gravel placed over the original soil after the topsoil was re- 

moved. Monitoring of these systems revealed that inadequate treatment 

occured before the groundwater was reached, and seepage often occurred 

during wet periods of the year. Successful modifications of the design 

were made to overcome these limitations (4). Mound systems are now used 

under a variety of conditions. 

A mound system is a soil absorption system that is elevated above the 

natural soil surface in a suitable fill material. The purpose of the 

design is to overcome site restrictions that prohibit the use of conven- 

tional soil absorption systems (4)(24). Such restrictions are: (1) 

slowly permeable soils, (2) shallow permeable soils over creviced or 

porous bedrock, and (3) permeable soils with high water tables. In 

slowly permeable soils, the mound serves to improve absorption of the 

effluent by utilizing the more permeable topsoil and eliminating con- 

struction in the wetter and more slowly permeable subsoil, where smear- 

ing and compaction are often unavoidable. In permeable soils with 

insufficient depth to groundwater or creviced or porous bedrock, the 

fill material in the mound provides the necessary treatment of the 

wastewater (see Figure 7-10). 

The mound system consists of: (1) a suitable fill material, (2) an ab- 

sorption area, (3) a distribution network, (4) a cap, and (5) top soil 

(see Figure 7-11). The effluent is pumped or siphoned into the absorp- 

tion area through a distribution network located in the upper part of 

the coarse aggregate. It passes through the aggregate and infiltrates 

the fill material. Treatment of the wastewater occurs as it passes 

through the fill material and the unsaturated zone of the natural soil. 

The cap, usually a finer textured material than the fill, provides frost 

protection, sheds precipitation, and retains moisture for a good vegeta- 

tive cover. The topsoil provides a growth medium for the vegetation. 

239

Straw, Hay or Fabric? 

FIGURE 7-10 

TYPICAL MOUND SYSTEMS 

Cap 

roistribution Lateral 

(a) Cross Section of a Mound System for Slowly Permeable 

Soil on a Sloping Site. 

Straw, Hay or Fabric--\ 

Cap 

7 

/- Distribution Lateral 

(b) Cross Section of a Mound System for a Permeable Soil, 

with High Groundwater or Shallow Creviced Bedrock 

240 

Absorption Bed

Id 

FIGURE 7-11 

DETAILED SCHEMATIC OF A MOUND SYSTEM 

Layer of Straw 

:a 

or Marsh Hay 7 "A'1 Perf~~~tfJ 


a. Site Considerations 

\ h.\%c 6" Topsoil 

Site criteria for mound systems are summarized in Table 7-7. These 

criteria reflect current practice. Slope limitations for mounds are 

more restrictive than for conventional systems, particularly for mounds 

used on sites with slowly permeable soils. The fill material and na- 

tural soil interface can represent an abrupt textural change that re- 

stricts downward percolation, increasing the chance for surface seepage 

from the base of the mound. 

241

I tern 

Landscape Position 

Slope 

Typical Horizontal Separation 

Distances from Edge of Basal Area 

Water Supply Wells 

Surface Waters, Springs 

Escarpments 

Boundary of Property 

Building Foundations 

Soil Profile Description 

Unsaturated Depth 

TABLE 7-7 

SITE CRITERIA FOR MOUND SYTSTEMS 

242 

Criteria 

Well drained areas, level or 

sloping. Crests of slopes or 

convex slopes most desirable. 

Avoid depressions, bases of slopes 

and concave slopes unless suitable 

drainage is provided. 

0 to 6% for soils with percolation 

rates slower than 60 min/in.a 

0 to 12% for soils with percolation 

rates faster than 60 min/in." 

50 to 100 ft 

50 to 100 ft 

10 to 20 ft 

5 to 10 ft 

10 to 20 ft 

(30 ft when located upslope from a 

building in slowly permeable 

soils). 

Soils with a well developed and 

relatively undisturbed A horizon 

(topsoil) are preferable. Old 

filled areas should be carefully 

investigated for abrupt textural 

changes that would affect water 

movement. Newly filled areas 

should be avoided until proper 

settlement occurs. 

20 to 24 in. of unsaturated soil 

should exist between the original 

soil surface and seasonally 

saturated horizons or pervious or 

creviced bedrock.

Depth to Impermeable Barrier 

Percolation Rate 


3 to 5 ftb 

0 to 120 min/in. measured at 12 to 

20 in.c 

a These are present limits used in Wisconsin established to coincide 

with slope classes used by the Soil Conservation Service in soil 

mapping. Mounds have been sited on slopes greater than these, but 

experience is limited (25). 

b Acceptable depth is site dependent. 

c Tests are run at 20 in. unless water table is at 20 in., in which 

case test is run at 16 in. In shallow soils over pervious or creviced 

bedrock, tests are run at 12 in. 

243

The acceptable depth to an impermeable layer or rock strata is site spe- 

cific. Sufficient depth must be available to channel the percolating 

wastewater away from the mound (see Figure 7-10). If not, the soil 

beneath the mound and the fill material may become saturated, resulting 

in seepage of effluent on the ground surface. The suggested depths to 

an impermeable layer given .in Table 7-7 may be adjusted in accordance 

with the site characteristics. Soil permeability, climate, slope, and 

mound layout determine the necessary depth. Slowly permeable soils 

require a greater depth to remove the liquid than do permeable soils. 

Frost penetration reduces the effective depth and therefore a greater 

depth is required in areas with severe winters. Level sites require a 

greater depth because the hydraulic gradients in the lateral direction 

are less than on sloping sites. Finally, mound systems extended along 

the contour of a sloping site require less depth than a square mound. 

Not enough research information is available to give specific depths for 

these various conditions. Until further information is available, 

mounds on slowly permeable soils should be made as long as possible, 

with the restricting layer at least 3 ft (0.9 ml below the natural soil. 

b. Influent Wastewater Characteristics 

The wastewater entering the mound system should be nearly free from set- 

tleable solids, greases, and fats. Septic tanks are commonly used for 

pretreatment and have proved to be satisfactory. Water softener wastes 

are not harmful to the system nor is the use of common household chemi- 

cals and detergents (9)(10). 


a. Fill Selection 

The mound design must begin with the selection of a suitable fill mater- 

ial because its infiltrative capacity determines the required absorption 

bed area. Medium texture sands, sandy loams, soil mixtures, bottom ash, 

strip mine spoil and slags are used or are being tested (24). To keep 

costs of construction to a minimum, the fill should be selected from 

locally available materials. Very permeable materials should be 

avoided, however, because their treatment capacity is less and there is 

a greater risk of surface seepage from the base of the mound when used 

over the more slowly permeable soils. Commonly used fill materials and 

their respective design infiltration rates are presented in Table 7-8. 

244

Fill Material Characteristicsa 

Medium Sand 


Sand/Sandy Loam 

Mixture 

Bottom Ash 

a Percent by weight. 

>25% 

FIGURE 7-12 

PROPER ORIENTATION OF A MOUND SYSTEM ON A COMPLEX SLOPE 

of Flow 

c. Sizing the Filled Area 

Mound Shaped to Co 

the Contour and to S 

The dimensions of the mound are dependent on the size and shape of the 

absorption bed, the permeability of the natural soil, the slope of the 

site, and the depth of fill below the bed (see Figure 7-13). Depths and 

dimensions are presented in Table 7-9. 

The downslope setback (I) in Figure 7-13 is dependent on the permeabili- 

ty of the natural soil. The basal area of the mound must be sufficient- 

ly large to absorb the wastewater before it reaches the perimeter of the 

mound or surface seepage will result. On level sites, the entire basal 

area (L x W) is used to determine I. However, on sloping sites, only 

the area below and downslope from the absorption bed is considered C(B) 

x (A + III. The infiltrative rates used for the natural soil to size 

the downslope setback are given in Table 7-10. These rates assume that 

a clogging mat forms at the fill/natural soil interface, which may not 

be true. Since the percolating wastewater can and does move laterally 

from this area, these values are conservative. However, for soils with 

percolation rates faster than 60 min/in. (24 min/cm), the side slope 

criteria determine the basal area instead of the infiltration rate of 

246

Straw or Marsh Hay, 

Medium Sand Fill 

Distribution 

Laterals q 

Bed of 

3/"-21/z“ Rock- 

FIGURE 7-13 

MOUND DIMENSIONS 

Perforated 

Pipe 

, 

Plowed Surface 3/4-21h in. Rock 

(A) Cross Section 

W 

-Slope 

(B) Plan View 

247 

I 

iClay Fill or 

3 ’

Mound Height 

TABLE 7-9 

DIMENSIONS FOR MOUND SYSTEMSa (25) 

Item Dimension 

Fill Depth (D), ft 1 (minjb 

Absorption Bed Depth (F), in. 9 (min) 

Cap at Edge of Bed (G), ft .lC 

Cap at Center of Bed (HI, ft 1.v 

Mound Perimeter 

Downslope Setback (I) 

Upslope Setback (J), ft 

Side Slope Setback (lo, ft 

Depends on Soil Permeability 

10d 

10d 

Side Slopes No Steeper Than 3:l 

a Letters refer to lettered dimensions in Figure 7-13. 

b On sloping sites, this depth wi,ll increase downslope to maintain a 

level bed. In shallow soils where groundwater contamination is a 

concern, the fill depth should be increased to 2 ft. 

c A 4-6 in. depth of quality topsoil is included. This depth can be 

decreased by 6 in. in areas with mild winters. If depths less than 

1 ft are used, erosion after construction must be avoided so 

sufficient soil covers the porous media. 

d Based on 3:l side slopes. On sloping sites, (J) will be less if 

3:l side slope is maintained. 

248

the top soil. It is only in the more slowly permeable soils where addi- 

tional basal area is required, and a conservative design may be appro- 

priate for these situations. 

TABLE 7-10 

INFILTRATION RATES FOR DETERMINING MOUND BASAL AREA (4) 

Natural Soil Texture 

Sand, Sandy Loam 

Loams, Silt Loams 

Silt Loams, Silty Clay Loams 

Clay Loams, Clay 

d. Effluent Distribution 

Percolation Infi 1 trati on 

Rate Rate 

ml n/in. gpdlft 

O-30 1.2 

31-45 0.75 

46-60 0.5 

61-120 0.25 

Although both gravity and pressure distribution networks have been used 

in mound systems, pressure distribution networks are superior (4)(24) 

(25). With pressure distribution, the effluent is spread more uniformly 

over the entire absorption area to minimize saturated flow through the 

fill and short circuiting, thus assuring good treatment and absorp- 

tion. Approximately four doses per day is suggested (25). The design 

of pressure distributed networks is found in Section 7.2.8. 

e. Porous Media 

The porous media placed in the absorption bed of the mound is the same 

as described in Section 7.2.2.3. 

f. Inspection Pipes 

Inspection pipes are not necessary, but can be useful in observing pond- 

ing depths in the absorption bed (see Figure 7-6) of the mound. 

249

Example 7.1: Calculation of Mound Dimensions and Pumping Requirements 

Design a mound for a 3 bedroom house with the following site conditions. 

Letter notations used in Figure 7-13 are used in this example. 

Step 1: 

Step 2: 

Step 3: 

Step 4: 

Step 5: 

Natural Soil Texture: Clay loam 

Percolation Rate at 20 in depth: 110 min/in. 

Depth to Seasonally High Water Table: 20 in. 

Slope: 6% 

No bedrock or impermeable layers 

Select the Site. The mound site should be selected prior to 

locating the house and the road when possible. Consider all 

criteria listed in Table 7-7 for possible mound locations on 

the lot. Consider the difficulties in construction of the 

mound at the various locations. Evaluate all criteria, then 

pick the best site. 

Select Suitable Fill Material. It may be necessary to make a 

SUbJeCtlVe Judgement on the quality of fill material versus 

transportation costs. The ideal fill material may not be 

readily available and thus selection of lesser quality fill may 

be practical. If finer, the loading rates used to design the 

absorption bed may have to be reduced. Assume a medium texture 

sand fpr this example. The design infiltration rate is 1.2 

gpd/ft (Table 7-8). 

Estimate Design Flow. Peak flow is estimated from the size of 

the building. In this instance, 150 gpd/bedroom is assumed 

(see Chapter 4). 

Size Absorption Bed. 

Absorption Bed Area = 

450 gpd 

1.2 gpd/ft2 

= 375 ft2 

Calculate Absorption Bed Dimension. The bed must parallel the 

site contour. Since the natural soil is slowly permeable, it 

is desirable to run the bed along the contour ,as far as possi- 

ble. In this example, assume sufficient area exists for a 65- 

ft length bed. 

Bed Width (A) = 375 = 5.8 ft or 6 ft

Bed Dimensions: A = 6 ft 

B = 65 ft 

Step 6: Calculate Mound Dimensions. 

a. Mound Height 

Fill Depth (D) = 1 ft (Table 7-9) 

Fill Depth (E) = D + [(Slope) x (A)] 

= 1 ft + C(O.06) x (6)1 

= 1.4 ft (This is only approximate. Criti- 

cal factor is construction of level bed 

bottom.) 

Bed Depth (F) q 9 in. (min) (Table 7-9). (A minimum of 6 

in. must be below the inverts of the dis- 

tribution laterals.) 

Cap at Edge of Bed (G) = 1 ft (min) (Table 7-9) 

Cap at Center of Bed (H) = l-1/2 ft (min) (Table 7-9) 

b. Mound Perimeter 

Downslope Setback (I): The area below and downslope of the 

absorption bed and sloping sites must be sufficiently large 

to absorb the peak wastewater flow. Select the proper 

natural soil infiltration 

case, the natural soil 

rate 

infiltration 

from Table 7-10. In 

rate is 0.25 gpd/ft 

his 

t 

. 

Upslope Setback (J) = (mound height at upslope edqe of bed) 

X (3:l slope) ’ ’ - 

Side Slope Setback (K) = 

= 

= 

= 

= 

L(D) + (E) + (G)l x (3) 

(1.0 + 0.75 + 1.0) x (3) 

(2.75) x (3) 

8.25 ft (This will be less because 

of natural ground slope, use 8 ft.) 

(s;~;;;' height at bed' center) x (3:l 

1 

2 

(D) + (E) 

+ (F) + (H) x (3)

1.0 + 1.4 

= - t 0.75 + 1.5 

1 

[ 

= (3.5) x (3) 

= 10.5 ft, or 11 ft 

Basal Area Required = (B) x t(I) + (AlI 

(I) + (A) = ,e 

= m-%&$ = 1,800 ft2 

. 

(I) = # - (A) 

1,800 

= ---6 

= 21.7 ft, or 22 ft 

x (3) 

Check to see that the downslope setback (I) is great 

enough so as not to exceed a 3:l slope: 

(mound height at downslope edge of bed) x (3:l slope) 

= C(E) + 

= (1.4 + 

= 9.5 ft 

(F) + (G)] x (3) 

0.75 + 1.0) x (3) 

Since 

less 

the 

than 

distance needed to maintain a 3:l slope is 

the distance needed to provide sufficient 

basal area, (I) = 22 ft 

Mound Length (L) = (8) + 2(K) 

= 65 + 2 (11) 

= 87 ft 

Mound Width (W) = (J) + (A) + (I) 

= 8 + 6 + 22 

= 36 ft 

252

Step 7: ,Design Effluent Distribution Network. See Section 7.2.8(f). 


a. Site Preparation 

Good construction techniques are essential if the mound is to function 

properly. The following techniques should be considered: 

Step 1: Rope off the site to prevent damage to the area during other 

construction activity on the lot. Vehicular traffic over the 

area should be prohibited to avoid soil compaction. 

Step 2: Stake out the mound perimeter and bed in the proper orienta- 

tion. Reference stakes set some distance from the mound peri- 

meter are also required in case the corner stakes are dis- 

turbed. 

Step 3: Cut and remove any excessive vegetation. Trees should be cut 

at ground surface and the stumps left in place. 

Step 4: Measure the average ground elevation along the upslope edge of 

the bed to determine the bottom elevation of the bed. 

Step 5: Install the delivery pipe from the dosing chamber to the 

mound. Lay the pipe below the frost line or slope it uniformly 

back to the dosing chamber so it may drain after dosing. Back 

fill and compact the soil around the pipe. 

Step 6: Plow the area within the mound perimeter. Use a two bottom or 

larger moldboard plow, plowing 7 to 8 in. (18 to 20 cm) deep 

parallel to the contour. Single bottom plows should not be us- 

ed, as the trace wheel runs in every furrow, compacting the 

soil. Each furrow should be thrown upslope. A chisel plow may 

be used in place of a moldboard plow. Roughening the surface 

with backhoe teeth may be satisfactory, especially in wooded 

sites with stumps. Rototilling is not recommended because of 

the damage it does to the soil structure. However, rototilling 

may be used in granular soils, such as sands. 

Plowing should not be done when the soil is too wet. Smearing 

and compaction of the soil will occur. If a sample of the soil 

taken from the plow depth forms a wire when rolled between the 

palms, the soil is too wet. If it crumbles, plowing may 

proceed. 

253

. Fill Placement 

Step 1: Place the fill material on the upslope edges of the plowed 

area. Keep trucks off the plowed area. Minimize traffic on 

the downslope side. 

Step 2: Move the fill material into place using a small track type 

tractor with a blade. Always keep a minimum of 6 in. of mate- 

rial beneath the tracks of the tractor to minimize compaction 

of the natural soil. The fill material should be worked in 

this manner until the height of the fill reaches the elevation 

of the top of the absorption bed. 

Step 3: With the blade of the tractor, form the absorption bed. Hand 

level the bottom of the bed, checking it for the proper eleva- 

tion. Shape the sides to the desired slope. 

c. Distribution Network Placement 

Step 1: Carefully place the coarse aggregate in the bed. Do not create 

ruts in the bottom of the bed. Level the aggregate to a 

minimum depth of 6 in. (15 cm). 

Step 2: Assemble the distribution network on the aggregate. The mani- 

fold should be placed so it will drain between doses, either 

out the laterals or back into the pump chamber. The laterals 

should be laid level. 

Step 3: Place additional aggregate to a depth of at least 2 in. (5 cm) 

over the crown of the pipe. 

Step 4: Place a suitable backfill barrier over the aggregate. 

d. Covering 

Step 1: Place a finer textured soil material such as clay or silt loam 

over the top of the bed to a minimum depth of 6 in. (15 cm). 

Step 2: Place 6 in. (15 cm) of good quality topsoil over the entire 

mound surface. 

Step 3: Plant grass over the entire mound using grasses adapted to the 

area. Shrubs can be planted around the base and up the side- 

slopes. Shrubs should be somewhat moisture tolerant since the 

downslope perimeter may become moist during early spring and 

late fall. Plantings on top of the mound should be drought 

254

tolerant, as the upper portion of the mound can become dry 

during the summer. 


a. Routine Maintenance 

A properly designed and constructed mound should operate satisfactorily 

with virtually no regular maintenance. 

b. Rehabilitation 

Three failure conditions may occur within the mound. They are (1) se- 

vere clogging at the bottom of the absorption area, (2) severe clogging 

at the fill material and natural soil interface, and (3) plugging of the 

distribution network. Usually these failures can be easily corrected. 

If severe clogging occurs at the bottom of the absorption bed, its cause 

should first be determined. If it is due to failure to maintain the 

pretreatment unit, hydrogen peroxide to oxidize the accumulated organics 

at the infiltrative surface could be used. The chemical can be applied 

directly to the bed or through the dosing chamber. Because of the dan- 

ger in handling this strong oxidant, this treatment should be done by 

professionals. 

If the clogging is due to overloading or unusual wastewater charac- 

teristics, efforts should be made to reduce the wastewater volume or 

strength. It may be necessary to enlarge the mound. The mound cap 

should be removed and the aggregate in the absorption bed stripped out. 

The area dotinslope of the mound should be plowed and additional fill 

added to enlarge the mound to the proper size. The absorption bed can 

then be reconstructed. 

Severe clogging at the fill and natural soil interface will cause sur- 

face seepage at the base of the mound. This area should be permitted to 

dry and the downslope area plowed. Additional fill can then be added. 

If this does not correct the problem, the site may have to be abandoned. 

Partial plugging of the distribution piping may be detected by extremely 

long dosing times. The ends of the distribution laterals should be ex- 

posed and the pump activated to flush out any solid material. If neces- 

sary, the pipe can be rodded. 

255



Designs of the mound system for larger flows follow the same design 

principles as for smaller flows. In cluster systems serving more than 

five homes, however, peak flow estimates can be reduced because of flow 

attenuation, but contributions from infiltration through the collection 

system must be included. Peak flow estimates should be based on the to- 

tal number of people to be served (see Chapter 4). Rates of infiltra- 

tion vary with the type of collection sewer used (19)(20). 

With commercial flows, the character of the wastewater is an important 

consideration. Proper pretreatment is necessary if the character is 

significantly different than domestic wastewater. 

Modifications to the design of the mound system may be desirable for 

larger flows on sloping sites or in slowly permeable soils. In both 

instances, the absorption area should be broken up into a series of 

trenches or smaller beds. This is beneficial on sloping sites because 

the beds can be tiered to reduce the amount of fill required (see Figure 

7-14). Depths of fill material below beds should not exceed 4 to 5 ft 

(1.3 to 1.7 ml because differential settling will cause the bed to set- 

tle unevenly. If the system is tiered, each trench or bed must be dosed 

individually. This can be done by automatic valving or alternating 

pumps or siphons. 

In sites with slowly permeable soils, breaking the absorption area into 

smaller trenches or beds helps distribute the effluent over much wider 

areas. Spacing of the beds or trenches should be sufficient so that the 

wastewater contributed from one trench or bed is absorbed by the natural 

soil before it reaches the lower trench or bed (see Table 7-10). The 

beds or trenches should be as long as the site allows. A long bed, bro- 

ken into several shorter systems, each served by a pump or siphon, is 

preferred over two or more short parallel beds, especially in soils 

where the effluent moves downslope. 

Flexibility in operation should also be incorporated into systems serv- 

ing larger flows, since a failure can create a significant problem. 

Alternating bed. 'systems should be considered. A three-bed system is 

suggested where each bed contains 50% of the required absorption area 

(19). Two beds are always in operation, providing 100% of the needed 

infiltrative surface. The third bed is alternated into service on a 

yearly schedule. Thus, each field is in service for two years and 

"rested" for one year to rejuvenate. The third bed also acts as a 

standby unit in case one bed fails. The idle fields can be put into 

service immediately while the failed bed is rehabilitated. 

256

7.2.5 Fill Systems 


FIGURE 7-14 

TIERED MOUND SYSTEM 

Fill systems may be used on sites with slowly permeable soils overlying 

sands and sandy loams where construction of a conventional system below 

the tight soil horizons may be ruled out. If the depth from the top 

surface of the underlying sand or sandy loam to the seasonally high 

water table or bedrock is inadequate to construct a trench or bed sys- 

tem, the slowly permeable soil may be stripped away and replaced with a 

sandy fill material to provide 2 to 4 ft (0.6 to 1.2 m) of unsaturated 

soil. A trench or bed system may then be constructed within the fill. 

Mound systems would also be suitable designs for these conditions and 

may be less expensive to construct, but fill systems offer some advan- 

tages. If the soils overlying the sands or sandy loams are very slowly 

permeable, the size of a fill system may be smaller than that of a mound 

permitting their installation in smaller areas. Also, fill systems usu- 

ally have less vertical relief above the natural grade than do mounds, 

This may be desirable for landscaping purposes. 

257


a. Site Considerations 

The use of fills is restricted to sites where unsuitable surface soils 

may be stripped away without damaging the underlying soils. Therefore, 

fills are limited to sites where the underlying soils are sands or sandy 

loams and the seasonally high water table or bedrock surface is not 

within 1 ft (0.3 m) of the sand or sandy loam surface. If the depth to 

the seasonally high water table or bedrock is greater than 3 to 5 ft 

(0.9 to 1.5 m) from the sandy or sandy loam surface, a fill system is 

not necessary. A deep trench or bed system can be constructed directly 

in the more permeable underlying area. 

Once the fill is placed, the site must meet all the site and soil crite- 

ria required for trench or bed systems (see Table 7-l). 

b. Influent Wastewater Characteristics 

The influent wastewater must be free of settleable solids, fats, and 

grease. Water softener wastes are not harmful, nor is the normal use of 

household chemicals and detergents. 


Since fill systems differ from trench and bed systems only in that they 

are constructed in a filled area, the design of fill systems is identi- 

cal to trenches and beds. The only unique features are the sizing of 

the area to be filled and the fill selection. Uniform distribution of 

the wastewater over the infiltrative surface through a pressurized net- 

work is suggested to maintain groundwater quality (11). 

a. Sizing of the Filled Area 

A minimum separation distance of 5 ft (1.5 m) between the sidewalls of 

the absorption trenches or bed, and the edge of the filled area should 

be maintained. This allows for sidewall absorption and lateral movement 

of the wastewater. 

258

If a perched water table condition occurs in the surface soils that are 

to be moved, provisions should be made to prevent this water from flow- 

ing into the filled area. Curtain drains, perimeter drains or barrier 

trenches may be necessary upslope or around the filled area to remove 

this water (see Section 7.2.6). 

b. Fill Selection 

The fill material should be similar in texture to the underlying sand or 

loamy sand. The backfill material used to cover the system should be 

finer textured to shed surface runoff. It may be the original soil that 

was removed. 


Care should be exercised in removing the unsuitable soil prior to fill- 

ing to prevent excessive disturbance of the sandy soil below. The 

machinery should always operate from unexcavated areas. The top few 

inches of the sand or sandy loam soil should be removed to ensure that 

all the unsuitable soil is stripped. 

The exposed surface should be harrowed or otherwise broken up to a depth 

of 6 in. (15 cm) prior to filling. This eliminates a distinct interface 

forming between the fill and the natural soil that would disrupt liquid 

movement. 

Once the fill has been placed, construction of the absorption system can 

proceed as for trenches or beds in sands. However, if the fill depth is 

greater than 4 ft (1.2 m), the fill should be allowed to settle before 

construction begins. This may require a year to settle naturally. To 

avoid this delay, the fill can be spread in shallow lifts and each me- 

chanically compacted. This must be done carefully, however, so that 

layers of differing density are not created. The fill should be com- 

pacted to a density similar to the underlying natural soil. 


The operation and maintenance of fill systems are identical to trenches 

and beds constructed in sands. The fill system lends itself very well 

to treatment with chemical oxidants or reconstruction in the same area. 

259

7.2.6 Artificially Drained Systems 


High water tables that limit the use of trenches, beds or seepage pits 

can sometimes be artificially lowered to permit the use of these dispo- 

sal methods. Vertical drains, curtain drains and underdrains are com- 

monly used subsurface drainage techniques. Soil and site conditions 

determine which method is selected. 

Curtain drains and vertical drains are used to lower perched water 

tables. These methods are most effective where the perched water is 

moving laterally under the soil absorption site. The drains are placed 

upstream of the absorption area to intercept the groundwater as it flows 

into the area. 

Curtain drains are trench excavations in which perforated drainage pipe 

is placed. These are placed around the upslope perimeter of the soil 

absorption site to intercept the groundwater moving into the area (see 

Figure 7-15). If the site has sufficient slope, the drains are brought 

to the surface downslope to allow free drainage. On level sites, pumps 

must be used to remove the collected water. If the restrictive layer 

that creates the water table is thin and overlies permeable soil, verti- 

cal drains may be used. These are trench excavations made through the 

restrictive layer into the more permeable soil below and backfilled with 

porous material (see Figure 7-16). Thus, water moving toward the ex- 

cavation is able to drain into the underlying soil. Vertical drains are 

susceptible to sealing by fine sediment transported by the water. 

Underdrains are used where water tables exist 4 to 5 ft (1.2 to 1.5 m) 

below the surface in permeable soils. The drains are similar to curtain 

drains in construction, but several drains may be necessary to lower the 

water table sufficiently (see Figure 7-17). Depth and spacing of the 

drains are determined by the soil and water table characteristics. 


Successful design of artificially drained systems depends upon the cor- 

rect diagnosis of the drainage problem. The source of the groundwater 

and its flow characteristics must be determined to select the proper 

method of drainage. Particular attention must be given to soil strati- 

fication and groundwater gradients. 

260

Perchc 

Wate 

Curtain 

Drain- 

FIGURE 7-15 

CURTAIN DRAIN TO INTERCEPT LATERALLY MOVING PERCHED WATER 

TABLE CAUSED BY A SHALLOW, IMPERMEABLE LAYER 

T-.y,,Drainage Pipe 

- 

FIGURE 7-16 

\(*- Absorption 

Trenches 

VERTICAL DRAIN TO INTERCEPT LATERALLY MOVING PERCHED WATER TABLE 

CAUSED BY A SHALLOW, THIN, IMPERMEABLE LAYER 

Vertical 

I 

Impermeable Layer l 

.

---- 

FIGURE 7-17 

UNDERDRAINS USED TO LOWER WATER TABLE 

le- Above High 

@ Water Table 

Underdrains 

a. Subsurface Drainage Problems 

Y Drainage Pipe / 

There is an unlimited variety of subsurface drainage problems but the 

most common ones can be grouped into four general types (26). These 

are: (1) free water tables, (2) water tables over artesian aquifers, 

(3) perched water tables, and (4) lateral groundwater flow problems. 

Free water tables typically are large, slow moving bodies of water fed 

by surface waters, precipitation, and subsurface percolation from other 

areas. In the lower elevations of the drainage basin, the groundwater 

is discharged into streams, on the ground surface in low areas, or by 

escape into other aquifers. The groundwater elevation fluctuates 

seasonally. The slope of a free water table surface is usually quite 

gentle. 

262

Where the soil is permeable, underdrains can be used to lower the water 

table sufficiently to permit the installation of trench or bed disposal 

systems. In fine textured soils of slow permeability, however, subsur- 

face drainage is impractical. 

An artesian aquifer is a groundwater body confined by an impervious 

layer over the aquifer. Its pressure surface ( the elevation to which 

it would rise in a well tapping the aquifer) is higher than the local 

water table, and may even rise above the ground surface. Pressure in 

the aquifer is caused by the weight of a continuous body of water that 

is higher than the local water table. Leaks at holes or weak points in 

the confining layer create an upward flow, with the hydraulic head 

decreasing in the upward direction. The groundwater moves in the 

direction of the decreasing gradient and escapes as seepage at the 

ground surface or moves laterally into other aquifers. 

Areas with this problem are impractical to drain. The water removed is 

continually replenished from the aquifer. This requires relatively deep 

and closely spaced drains and pumped discharges. Onsite disposal op- 

tions other than soil absorption systems should be investigated in areas 

with shallow artesian aquifers. 

In stratified soils, a water table may develop that is separated from 

the free water table by a slowly permeable layer, i.e., a perched water 

table. This occurs when surface sources of water saturate the soil 

above the layer due to slow natural drainage. Methods employed to drain 

perched water tables depend upon the particular site conditions. Verti- 

cal drains, curtain drains or underdrains may be used. 

Lateral groundwater flow problems are characterized by horizontal 

groundwater movement across the area. This flow pattern is usually 

created by soil stratification or other natural barriers to flow. 

The depth, orientation and inclination of the strata or barriers deter- 

mine the drainage method used and its location. Curtain drains or vert- 

ical drains are usually employed to intercept the water upstream of the 

area to be drained. 

b. Site Evaluation 

Soils with high water tables that may be practical to drain to make a 

site suitable for a trench or bed system are ones having (1) shallow 

perched water tables, (2) lateral groundwater flow, or (3) free water 

tables in coarse textured soils. Soils that are saturated for prolonged 

263

periods, particularly on level sites, are not practical to drain. Other 

disposal methods should be investigated for such sites. 

Because each of these drainage problems require different solutions, it 

is important that the site 'evaluation be done in sufficient detail to 

differentiate between them. Where the need for subsurface drainage is 

anticipated, topographic surveys, soil profile descriptions and estima- 

tion of the seasonally high groundwater elevations and gradients should 

be emphasized. Evaluation of these site characteristics must be done in 

addition to other characteristics that are evaluated for subsurface dis- 

posal (see Chapter 3). 

Topographic Surveys: Topographic maps of the site with 1 to 2 ft (0.3 

to 0.6 m) contour intervals are useful as base maps on which water and 

soils information can be referenced. Water table elevations, seep areas 

and areas with vegetation indicative of seasonal or prolonged high water 

tables should be locat* In the map. Elevations of ridges, knolls, rock 

outcrops and natural drainage ways should also be noted. This informa- 

tion is useful in establishing the source of the groundwater, its direc- 

tion of flow, and the placement of the drainage system. 

Soil Profile Descriptions: The soil profile must be carefully examined 

to identify the type ot drainage problem and the extent of seasonal 

water table fluctuations. Soil stratification and soil color are used 

to make these determinations. 

Soil stratification or layering may or may not be readily visible. Soil 

texture, density, color, zones of saturation and root penetration aid in 

identifying layers of varying hydraulic conductivity (see Chapter 3). 

The thickness and slope of each layer should be described. Deep uniform 

soils indicate that the drainage problem must be handled as a free water 

table problem. Stratified soils indicate a perched or lateral flow 

groundwater problem. 

The soil color helps to identify zones of periodic and continous satura- 

tion. Soil mottling occurs when the soil is periodically saturated, and 

gleyed soil indicates continuous saturation (see Chapter 3). The high- 

est elevation c$ the mottling provides an estimate of the seasonally 

high water table, while the top of the gleyed zone indicates the season- 

ally low water table elevation. It is particularly important to estab- 

lish the extent of the seasonal fluctuations to determine if drainage is 

practical. If the seasonally low water table is above the elevation to 

which the soil must be drained to make the site acceptable, drainage 

must be provided throughout the year. If pumps are used to remove the 

water, costs may be excessive and other alternatives should be 

investigated. 

264

Groundwater, Elevation and Gradients: To accurately determine ground- 

water elevations and gradients, observation wells or piezometers are 

used. Observation wells are used to observe groundwater flutuations 

throughout a year or more. If several are strategically placed about 

the area, the local gradient can also be established by measuring the 

water surface elevation in each well. Piezometers differ from obser- 

vation wells in that they are constructed so that there is no leakage 

around the pipe. The water surface elevation measured establishes the 

hydrostatic pressure at the bottom of the well. If placed at several 

depths, they can be used to establish whether artesian conditions exist. 

For construction of piezometers and interpretation of results, see USDA, 

"Drainage of Agricultural Land" (26). 

The measured or estimated water table elevations for a specific time 

period are plotted on the topographic map. By drawing the contours of 

the water table surface from these plots, the direction of groundwater 

movement is determined, since movement is perpendicular to the ground- 

water contours. This helps locate the source of the water and how to 

best place the drainage network. 


a. Selection of Drainage Method 

In designing a subsurface drainage system, the site characteristics are 

evaluated to determine which method of drainage is most appropriate. 

Table 7-11 presents the drainage method for various site 

characteristics. In general, shallow, lateral flow problems are the 

easiest drainage problems to correct for subsurface wastewater disposal. 

Since the use of underdrains for onsite disposal systems has been very 

limited, other acceptable disposal methods not requiring drains should 

first be considered. 

b. Curtain Drains 

Curtain drains are placed some distance upslope from the proposed soil 

absorption system to intercept the groundwater, and around either end of 

the system to prevent intrusion. On sites with sufficient slope, the 

drain is extended downslope until it surfaces, to provide free drainage. 

The drain is placed slightly into the restrictive layer to ensure that 

all the groundwater is intercepted. A separation distance from the soil 

absorption system is required to prevent insufficiently treated waste- 

water from entering the drain. This distance depends on the soil perme- 

ability and depth of drain below the bottom of the absorption system; 

however, a separation distance of 10 ft is commonly used. 

265

TABLE 7-11 

DRAINAGE METHODS FOR VARIOUS SITE CHARACTERISTICS 

Site Characteristics 

Saturated or mottled soils above a 

restrictive layer with water source 

located at a higher elevation; site 

usually sloping 

Saturated or mottled soils above a 

restrictive layer; soil below 

restrictive layer is unsaturated; 

site is level or only gently sloping 

Deep uniform soils mottled or 

saturated 

Saturated soils above and below 

restrictive layer with hydraulic 

gradients increasing with depth 

Drainage 

Problem 

Lateral flow 

Perched water 

table 

Free water 

table 

Artesian-fed 

water table 

Drainage Method 

Curtain drain 

Vertical draina 

Underdrainb 

Vertical draina 

Underdrainb 

Avoid 

a Use only where restrictive layer is thin and underlying soil is 

reasonably permeable. 

b Soils with more than 70% clay are difficult to drain and should be 

avoided. 

266 

-

The size of the drain is dependent upon the soil permeability, the size 

of the area drained, and the gradient of the pipe. Silt traps are some- 

times provided in the drain to improve the quality of the discharged 

drainage. These units may require infrequent cleaning to maintain their 

effectiveness. 

c. Vertical Drains 

Vertical drains may be used to intercept a laterally flowing perched 

water table. Separation distances between the drain and the bottom of 

the soil absorption system are the same as for curtain drains to main- 

tain an unsaturated zone under the absorption system. 

The size and placement of the drain depends upon the relative permeabil- 

ities of the saturated soil and the soil below the restrictive layer, 

and the size of the area to be drained. The infiltration surface of the 

vertical drain (sidewalls and bottom area) must be sized to absorb all 

the water it receives. The width and depth of the drain below the re- 

strictive layer is calculated by assuming an infiltration rate for the 

underlying soil. If clay and silt are transported by the groundwater, 

the infiltration rate will be less than the saturated conductivity of 

the soil. Clogging of the vertical drain by silt can be a significant 

problem. Unfortunately, experience with these drains in wastewater 

disposal is lacking. 

d. Underdrains 

Underdrains must be located to lower the water table to provide the 

necessary depth of unsaturated soil below the infiltrative surface of 

the soil absorption system, and to prevent poorly treated effluent from 

entering the drain. Sometimes, a network of drains is required through- 

out the area where the soil absorption system is located. The depth and 

spacing of the drains is determined by the soil permeability, the size 

of the area to be drained, and other factors. Where necessary, however, 

see USDA Drainage of Agricultural Land (26) for design procedures. 


a. Curtain Drains and Underdrains 

To maximize infiltration of the groundwater into the pipe, a coarse, 

porous material such as gravel, crushed rock, etc., should be placed 

under and above the pipe. The porous material is extended above the 

267

high water table elevation. To prevent silt from entering the pipe 

while the disturbed area is stabilizing, the tops of the joints or per- 

forations should be covered with waterproof building paper or the pipe 

jacketed with mesh. Natural soil material is used for the remainder of 

the backfill (27). 

The outlet must be protected from small animals. The outlet may be 

covered with a porous material such as rock or gravel. Various com- 

mercial outlet protection devices are also available (26). 

b. Vertical Drains 

Vertical drains are dug to the desired depth and width, and are back- 

filled with a coarse, porous media such as coarse sand, l/4- to l/2-in 

(0.6 to 1.3 cm) gravel, or similar material, to a level above the high 

perched water table elevation. Natural soil materials are used for the 

remainder of the backfill. 

7.2.6.5 Maintenance 

A well-designed and constructed drainage system requires little mainte- 

nance. The outlets should be inspected routinely to see that free 

drainage is maintained. If a silt trap is used, it should be inspected 

annually to determine the need for cleaning. 

7.2.7 Electra-Osmosis 


Electra-osmosis is a technique used to drain and stabilize slowly perme- 

able soils during excavation. A direct current is passed through the 

soil, which draws the free water in the soil pores to the cathode 

(28). The water collects at the cathode and is pumped out. Steel well 

points serve as cathodes, and steel rods driven between wells are used 

as anodes. Common practice is to install the electrodes approximately 

15 ft (4.6 m) apart, and apply a 30- to 180-volt potential. Current 

flow is 20 to 30 amps (28). 

Recently, a similar technique has been applied to onsite wastewater dis- 

posal in soils with percolation rates slower than 60 min/in. (24 

min/cm). A galvanic cell is constructed out of natural materials, which 

requires no external power source. This cell is capable of generating a 

268

0.7- to 1.3Avolt potential (29). Conventional absorption trenches are 

constructed and a mineral rock-filled anode is installed immediately 

adjacent to the trench. Coke-filled cathodes with graphite cores are 

installed some distance from the trench (see Figure 7-18). The water 

that moves to the cathode is claimed to be removed by evapotranspiration 

(30). These systems have been used successfully in California, Iowa, 

Minnesota, and Wyoming (29). 


Electra-osmosis systems were developed to enhance wastewater absorption 

in slowly permeable soils. They are used in soils with percolation 

rates slower than 60 min/in. (24 min/cm). Criteria for soil absorption 

trench or bed are presented in Table 7-l. 

7.2.7.3 Design and Construction 

The electro-osmosis system is patented. Design and construction of sys- 

tems are done by licensees. 


Once installed, no routine maintenance of the electrodes has been re- 

ported. Maintenance techniques for the. soil absorption trench are 

presented in Section 7.2.2.5. 

7.2.8 Effluent Distribution Network for Subsurface 

Soil Absorption Systems 

Several different distribution networks are used in subsurface soil 

absorption systems. They include single line, closed loop, distribution 

box, relief line, drop box, and pressure networks. The objective of 

each is to apply the pretreated wastewater over the infiltrative 

surface. 

The choice of one network over another depends on the type of system 

proposed and the method of wastewater application desired. Networks for 

the various types of systems versus the method of wastewater application 

are given in Table 7-12. Where more than one network is suitable, they 

are listed in order of preference. 

269

FIGURE 7-18 

TYPICAL ELECTRO-OSMOSIS SYSTEM (30) 

Anodes 

/ \ 

4” Graphite Cores 

Cathode 

14” Vents 

Plan View 

Slope 

-* Absorption 

Trench 

Section A-A 

270 

Anodes 

/ \

TABLE 7-12 

DISTRIBUTION NETWORKS FOR VARIOUS SYSTEM DESIGNS AND APPLICATION METHODSa 

Method Multi-Trench Multi-Trench 

of (Fills, Drains) (Drains) Beds 

Application Single Trench On Level Site On Sloping Site (Fills, Drains) Mounds 

Gravity Single line Drop box Drop box Closed loop Not applicable 

Closed loop Relief line Distribution box 

Distribution box Distribution boxb 

Dosing Single line Closed loop Distribution box Closed loop Not applicable 

Pressure Pressure Pressure 

Distribution box Distribution box 

N Uniform Pressure Pressure Pressurec Pressure Pressure 

4 

+ Application 

a Distribution networks are listed in order of preference. 

b Use limited by degree of slope (see Section 7.2.8.1 d) 

c Because of the complexity of a pressure network on a sloping site, drop boxes or relief lines are 

suggested.


a. Single Line . 

Single-line distribution networks are trenches loaded by gravity or 

dosing. The distribution line is a 3- to 4-in. (8- to lo-cm) diameter 

perforated pipe laid level in the center of the gravel-filled excavation 

(see Figure 7-19). The pipe is usually laid such that the holes are at 

or near the invert of the pipe. Where the length of single lines 

exceeds 100 ft (30 m), it is preferable to locate the wastewater inlet 

toward the center of the line. 

b. Drop Box 

Drop box networks are typically used for continuously ponded multi- 

trench systems on level to maximum sloping lots. It is a network that 

serially loads each trench to its full hydraulic capacity. 

A drop box is a small, circular or square box with a removable cover. 

It has an inlet, one or two distribution lateral outlets, and an over- 

flow. The lateral outlet inverts are located at or near the bottom of 

the box, all of the same diameter pipe. The overflow invert can be the 

same elevation as the crown of the lateral outlet, or up to 2 in. above 

it, to cause the full depth of the trench to flood. The inlet invert of 

the drop box may be at the same elevation as the overflow invert or a 

few inches above. An elevation difference of 1 to 2 in. (3 to 5 cm) 

between trenches is all that is needed to install a drop box network. 

The boxes may be buried, but it is suggested that the covers be left 

exposed for periodic inspection and maintenance (see Figure 7-20). 

Drop boxes are installed at the wastewater inlet of each trench. The 

inlets may be located anywhere along the trench length. A solid wall 

pipe connects the overflow from the higher box to the inlet of the lower 

box. The first box in the network receives all the effluent from the 

pretreatment tank and distributes it into the first trench. When the 

first trench fills, the box overflows into the next trench. In this 

manner, each trench in the system is used successively to its full capa- 

city. Thus, only the portion of the system required to absorb the 

wastewater is used. During periods of high flow or low absorptive capa- 

city of the soil, more trenches will be used. When flows are low or 

during the hot dry summer months, the lower trenches may not be needed, 

so they may drain and dry out, automatically resting more trenches, 

which rejuvenates their infiltrative surfaces (11). 

272

Pretreatment 

Unit 

FIGURE 7-19 

SINGLE LINE DISTRIBUTION NETWORK NETWORK 

Watertight 

Pipes and 

Joints 

4evel or 2 in. to 4 in. 

per 100 ft. Slope 

Overfill to Allow 

for Settlement 

Section A-A 

Distribution Pipe 

Crushed Stone 

273 

Section B-B

Inlet From 

Pretreatment 

or Previous 

FIGURE 7-20 

DROP BOX DISTRIBUTION NETWORK ([AFTER (2211 

Plan 

Trench 

-J~I Qyerflow --& 

Overflow 

to Next 

Drop Box 

Inlet 

nlltlet to 

I i----J] 

v--t? 

Outlets to 1 L---j 

Trench 

‘i-r- 

I 

I rench 

Profile End View 

Pretreatment 

-- Unit Water-T’ 

Dinnc 

rian Plan 

ox -7- 

Necessary 

Covers May be Exposed at 

Surface if Insulated in 

, Section A-A 

274

The liquid level in the trenches is established by the elevation of the 

overflow invert leading to the succeeding drop box. If the elevation of 

this invert is near the top of the rock in the trench, the entire trench 

sidewall will be utilized, maximum hydrostatic head will be developed to 

force the liquid into the surrounding soil, and evapotranspiration by 

plants during the growing season will be maximized by providing a supply 

of liquid to the overlying soil. 

The drop box design has several advantages over single lines, closed 

loop, and distribution box networks for continuously ponded systems. It 

may be used on steeply sloping sites without surface seepage occurring 

unless the entire system is overloaded. If the system becomes over- 

loaded, additional trenches can be added easily without abandoning or 

disturbing the existing system. Drop box networks also permit unneeded 

absorption trenches to rest and rejuvenate. The lower trenches are 

rested automatically when flows are low or infiltration capacity is 

high. The upper trenches may be rested when necessary by plugging the 

drop box lateral outlets. 

c. Closed Loop 

In absorption systems where the entire infiltrative surface is at one 

elevation, such as in beds or multi-trench systems on level or nearly 

level sites, closed loop networks may be used. The distribution pipe is 

laid level over the gravel filled excavation and the ends connected to- 

gether with additional pipe with ell or tee fittings. In beds, the 

parallel lines are usually laid with 3 to 6 ft (0.9 to 1.8 m) spacings. 

A tee, cross, or distribution box may be used at the inlet to the closed 

system (See Figure 7-21). 

d. Distribution Box 

Distribution box networks may be used in multi-trench systems or beds 

with independent distribution laterals. They are suitable for all gra- 

vity-flow systems. 

The distribution laterals in the network extend from a common watertight 

box called the distribution box. The box may be round or rectangular, 

with a single inlet, and an outlet for each distribution lateral. It 

has an exposed, removable cover. Its purpose is to divide the incoming 

wastewater equally between each lateral. To achieve this objective, the 

outlet inverts must be at exactly the same elevation. The inlet invert 

should be about 1 in. above the outlet inverts. Where dosing is em- 

ployed or where the slope of the inlet pipe imparts a significant velo- 

city to the wastewater flow, a baffle should be placed in front of the 

inlet to prevent short-circuiting. 

275

watertight Pipe & Joints1 

FIGURE 7-21 

CLOSED LOOP DISTRIBUTION NETWORK 

Pretreatment 

Unit 

Distribution box networks are suggested only for absorption systems 

located on level or gently sloping sites, where the system can be in- 

stalled so that the ground surface elevation above the lowest trench is 

above the box outlets (11). This is because it is difficult to prevent 

the distribution box from settling (11)(17)(31). If the box were to 

settle unevenly so that the lowest trench received a greater share of 

the effluent, wastewater would seep onto the ground surface unless the 

distribution lateral of the lowest trench were at a high enough eleva- 

tion to back up the wastewater into the box, where it could flow into a 

different lateral. Therefore, to utilize the full capacity of each 

trench in the system, distribution box networks should be used only 

where each trench can back up into the distribution box (see Figure 7- 

22). On steeply sloping sites, other networks should be used, unless 

great care is used to construct the distribution box on a stable 

footing. If used for dividing flow between independent trenches, any 

combination of trenches can be rested by plugging the appropriate 

outlets. 

e. Relief Line 

Relief line networks may be used in place of drop box networks in 

continuously ponded multi-trench systems on sites up to the maximum 

permissible slopes. The network provides serial distribution as in drop 

276

Distribution Box A 

Firmly Supported 

in Level Position 

at Same Elevation 

FIGURE 7-22 

D I STR IBUT ION BOX NETWORK 

istribution 

Pioes 

Central Feed 

End Feed 

Ground Surface at Lowest 

Trench Higher Than Outlets 

L Distribution 

Box 

Section A-A 

277 

rlpes 

,forated

ox networks (see Figure 7-23). However, .the design makes it more 

difficult to add trenches to the system and it does not permit the owner 

to manually rest the upper trenches. 

The network uses overflow or relief lines between trenches in place of 

drop boxes. The invert of the overflow section should be located near 

the top of the porous media to use the maximum capacity of the trench, 

but it should be lower than the septic tank outlet invert. The invert 

of the overflow from the first absorption trench should be at least 4 

in. lower than the invert of the pretreatment unit outlet. Relief lines 

may be located anywhere along the length of the trench, but successive 

trenches should be separated 5 to 10 ft (1.3 to 3.0 m) to prevent short- 

circuiting. 

f. Pressure Distribution 

If uniform distribution of wastewater over the entire infiltrative sur- 

face is required, pressure distribution networks are suggested. These 

networks may also be used in systems that are dosed since the mode of 

the network operation is intermittent. 

To achieve uniform distribution, the volume of water passing out each 

hole in the network during a dosing cycle must be nearly equal. To 

achieve this, the pressure in each segment of pipe must also be nearly 

equal. This is accomplished by balancing the head losses through proper 

sizing of the pipe diameter, hole diameter and hole spacing. Thus, 

approximately 75 to 85% of the total headloss incurred is across the 

hole in the lateral, while the remaining 15 to 25% is incurred in the 

network delivering the liquid to each hole. The networks usually con- 

sist of l- to 3-in. (3- to a-cm) diameter laterals, connected by a cen- 

tral or end manifold of larger diameter. The laterals are perforated at 

their inverts with l/4 to l/2 in. (0.6 to 1.3 cm) diameter holes. The 

spacing between holes is 2 to 10 ft (0.6 to 3.0 m) (see Figures 7-24 to 

27). 

Pumps are used to pressurize the network, although siphons may be used 

if the dosing chamber is located at a higher elevation than the lateral 

inverts. The active dosing volume is about 10 times the total lateral 

pipe volume. This ensures more uniform distribution since the laterals, 

drained after each dose, must fill before the network can become prop- 

erly pressurized. (See Section 8.3 for dosing chamber design.) 

278

FIGURE 7-23 

RELIEF LINE DISTRIBUTION NETWORK 

iFlow From Pretreatment Unit 

Distribution 

I 

Pipe 

I- 

PA 

Absorption 

Trenches 

Follow Cont:T[ 

I 

+ Relief 

1 Line 

IEnds Capped

280 

s 

P 

4

FIGURE 7-25 

END MANIFOLD DISTRIBUTION NETWORK

FIGURE 7-26 

LATERAL DETAIL - TEE TO TEE CONSTRUCTION 

Reducing Coupling Cap 

. 

Hole in Cap Near 

Crown for Air 

Venting in 

Larger Systems

,Staggered Tees or Cross. 

FIGURE 7-27 

LATERAL DETAIL - STAGGERED TEES OR CROSS CONSTRUCTION 

d-- Lateral 

Holes Spaced 

2 Ft. to 10 Ft. 

Hole in Cap 

Near Crown for 

Air Venting in 

Larger Systems

To simplify the design of small pressure distribution networks, Table 7- 

13, and Figures 7-28, 7-29, and 7-30, may be used. Examples 7-2 and 7-3 

illustrate their use. Other design methods may be equally suitable, 

however. 

Pressure 

ft JE. 

- 

1 0.43 

2 0.87 

3 1.30 

4 1.73 

5 2.17 

TABLE 7-13 

DISCHARGE RATES FOR VARIOUS SIZED HOLES 

AT VARIOUS PRESSURES (wm) 

l/4 

0.74 

1.04 

1.28 

1.47 

1.65 

Hole.Diameter (in.) 

5/16 3/8 l/16 

1.15 1.66 2.26 

1.63 2.34 3.19 

1.99 2.87 3.91 

2.30 3.31 4.51 

2.57 3.71 5.04 

Example 7-2: Design of a Pressure Distribution Network for a Trench 

Absorption Field 

Design a pressure network for an absorption field consisting of five 

trenches, each 3 ft wide by 40 ft long, and spaced 9 ft apart center to 

center. 

Step 1: Select lateral length. Two layouts are suitable for this 

system: central manifold (Figure 7-24) or end manifold (Figure 

7-25). For a central manifold design, ten ZO-ft laterals are 

used; for an end manifold design, five 40-ft laterals are 

required. The end manifold design is used in this example. 

Step 2: Select hole diameter and hdle spacing for laterals. For this 

example, l/4-ln. diameter holes spaced every 30 in. are used, 

although other combinations could be used. 

284 

l/2 

2.95 

4.17 

5.10 

5.89 

6.59

FIGURE 7-28 

REQUIRED LATERAL PIPE DIAMETERS FOR VARIOUS HOLE DIAMETERS, HOLE SPACINGS, AND LATERAL LENGTHSa 

(FOR PLASTIC PIPE ONLY) 

LATERAL DIAMETER (IN) 

Hole Diameter (in) Hole Diameter (in) Hole Diameter (in) Hole Diameter (in) Hole Diameter (in] 

-I- l/4 5116 3/8 7/16 l/2 

c-o-< 

Hole Spacing (ft) Hole Spacing (ft) Hole Spacing (ft) Hole Spacing (ft) Hole Spacing (ft) 

-I . . 

234567’234567234567234567234567 

Example 7-2 3” 

acomputed for plastic pipe only. The Hazen-Williams equation was used to compute headlosses 

through each pipe segment (Hazen-Williams C= 150). Thes6rifice equation for sharp-edged orifices 

(discharge coefficient = 0.6) was used to compute the discharge rates through each orifice. 

The maximum lateral length for a given hole and spacing was defined as that length at which the 

difference between the rates of discharge from the distal end and the supply end orifice reached 

10 percent of the distal end orifice discharge rate.

FIGURE 7-29 

RECOMMENDED MANIFOLD DIAMETERS FOR VARIOUS MANIFOLD LENGTHS, NUMBER OF LATERALS, 

AND LATERAL DISCHARGE RATES (FOR PLASTIC PIPE ONLY) 

MANIFOLD DIAMETER (IN) 

fold Length (ft) 

Cl...... ..,-.c r I *I- ’ 20 1 25 1 30 1 35 I 40 I 45 I 50 Flow per 

.-_a- . . ..&I_ P--*--l L”--:l-,A ’ Lateral 

1 Number of Laterals with End mi 

aComputed for plastic pipe only. The Hazer-r-Williams equation was used to compute headlosses 

through each segment (Hazen-Williams C = 150). The maximum manifold length for a given 

lateral discharge rate and spacing was defined as that length at which the difference 

between the heads at the distal and supply ends of the manifold exceeded 10 percent of the 

head at the distal end.

FIGURE 7-30 

NOMOGRAPH FOR DETERMINING THE MINIMUM DOSE VOLUME FOR A GIVEN LATERAL DIAMETER, 

LATERAL LENGTH, AND NUMBER OF LATERALS 

/ 

I 

r 4,000 

- 3,500 

- 3,000 

- 2.500 

. 2.000 

6 

- 1.000 > 

m 

03 

EXAMPLE 7-3 

EXAMPLE 7-2 / 

1 

15 

20 

287

Step 3: Select lateral diameter. For l/4-in. hole diameter, 30-in. 

hole spacing, and 40-ft length, Figure 7-28 indicates either a 

l-l/4-in. or l-l/2-in. diameter lateral could be used. The l- 

l/2-in. diameter is selected for this example. 

Step 4: Calculate lateral. discharge rate. By maintaining higher 

pressures in the lateral, small variations in elevation along 

the length of the lateral and between laterals do not signifi- 

cantly affect the rates of discharge from each hole. This 

reduces construction costs, but increases pump size. For this 

example, a 2-ft head is to be maintained in the lateral. For a 

l/4-in. hole at 2 ft of head, Table 7-13 shows the hole dis- 

charge rate to be 1.04 gpm. 

Number of holes/lateral = 40-ft 'a~~a~p~,':~,"h 

. - 

= 16 

Lateral discharge rate = (16 holes/lateral) x (1.04 gpm/hole) 

= 16.6 gpm/lateral 

Step 5: Select manifold size. There are to be five laterals spaced 9 

ft apart. A manifold length of 36 ft is therefore required. 

For five laterals and 16.6 gpm/lateral, Figure 7-29 indicates 

that a 3-in. diameter manifold is required. 

Step 6: Determine minimum dose volume (Figure 7-30). 

With: lateral diameter = l-l/Z in. 

lateral length = 40 ft 

number of laterals = 5 

Then: pipe volume = 3.7 gal 

Minimum dose volume = approx. 200 gal 

The final dose volume may be larger than this minimum depending 

on the desired number of doses per day (see Table 7-4). 

See Figure 7-31 for completed network design. 

Step 7: Determine minimum discharge rate. 

Minimum discharge rate = (5 laterals) x (16.6 gpm/lateral) 

= 83 gpm 

288

289

Step 8: Select proper pump or siphon. 

For a pump system, the total pumping head of the network must 

be calculated. This is equal to the elevation difference 

between the pump and the distribution lateral inverts, plus 

friction loss in the pipe that delivers the wastewater from the 

pump to the network at the required rate, plus the desired 

pressure to be maintained in the network (the velocity head is 

neglected). A pump is then selected that is able to,discharge 

the minimum rate (83 gpm) at the calculated pumping head. 

For a siphon system, the siphon discharge pipe must be elevated 

above the lateral inverts at a distance equal to the friction 

losses and velocity head in the pipe that delivers the waste- 

water from the siphon to the network at the required rate, plus 

the desired pressure to be maintained in the network. 

For this example, assume the dosing tank is located 25 ft from 

the network inlet, and the difference in elevation between the 

pump and the inverts of the distribution laterals is 5 ft. 

a. Pump (assume 3-in. diameter delivery pipe) 

1. Friction loss in 3-in. pipe at 83 gpm (from Table 7-14) 

Friction loss in 25 ft 

= 1.38 + 2 (1.73 - 1.38) 

= 1.49 ft/loo ft 

= (1.49 flYlO ft) x (25 ft) 

= 0.4 ft 

2. Elevation Head = 5.0 ft 

3. Pressure to be maintained = 2.0 

Total pumping head = 7.4 ft 

Therefore, a pump capable of delivering at least 83 gpm against 

7.4 ft of head is required. 

b. Siphon (assume 4-in. diameter delivery pipe) 

1. Friction loss in 4-in. pipe at83 gpm (from Table 7-14) 

= 0.37 + J-j (0.46 - 0.37) 

= 0.4 ft/loo ft 

290

Flow 

gw 

1 

% 

4 

5 

6 

7 

8 

1: 

:: 

13 

14 

15 

16 

:; 

:i 

50” 

do5 

io” 

Fi 

80 

90 

100 

150 

200 

250 

300 

350 

400 

450 

500 

600 

700 

800 

900 

1000 

TABLE 7-14 

FRICTION LOSS IN SCHEDULE 40 PLASTIC PIPE, C = 150 

(fW00 ft 1 

1 l-1/4 l-1/2 

Pipe Diameter 

3 L ? 3 

(in.) 

4 6 8 10 

- A I 

0.07 

0.28 0.07 

0.60 0.16 

1.01 0.25 

1.52 0.39 

2.14 0.55 

2.89 0.76 

3.63 0.97 

4.57 1.21 

5.50 1.46 

1.77 

2.09 

2.42 

2.74 

3.06 

3.49 

3.93 

4.37 

4.81 

5.23 

0.07 

0.12 

0.18 

0.25 

0.36 

0.46 

0.58 

0.70 

0.84 

1.01 

1.17 

1.33 

1.45 

1.65 

1.86 

2.07 

2.28 

2.46 

3.75 

5.22 

- - 

0.07 

0.10 

0.14 

0.17 

0.21 

0.25 

0.30 

0.35 

0.39 

0.44 

0.50 

0.56 

0.62 

0.68 

0.74 

1.10 

1.54 

2.05 

2.62 

3.27 

3.98 

291 

0.07 

0.08 

0.09 

0.10 

0.11 

0.12 

0.16 

0.23 

0.30 

0.39 

0.48 

0.58 

0.81 

1.08 

1.38 

1.73 

2.09 

0.07 

0.09 

0.12 

0.16 

0.21 

0.28 

0.37 

0.46 

0.55 0.07 

1.17 0.16 

0.28 0.07 

0.41 0.11 

0.58 0.16 

0.78 0.20 0.07 

0.99 0.26 0.09 

1.22 0.32 0.11 

0.38 0.14 

0.54 0.18 

0.72 0.24 

0.32 

0.38 

0.46


2. Velocity head in delivery pipe 

z ho;," ;;/lOO ft.1 x (25 ftl 

. 

Discharge rate = 83 gpm = 0.185 ft3/sec 

Area =(1/4)7r (;I2 = 0.087 ft2 

Velocity 

Velocity head = (VelocityJ2 

29 

= 0.185 ft3/sec = 2 l3 ft.sec 

0.087 ft2 * 

= (L2.131 ftlsec)' 

2(32.2 ft/sec2) 

= 0.07 ft 

3. Pressure to be maintained 

= 2.0 ft 

Total 2.2 ft 

Minimum elevation of the siphon discharge invert above the 

lateral inverts must be 2.2 ft. 

In summary, the final network design consists of five 40-ft laterals l- 

l/2 in. in diameter connected with a 36-ft end manifold 3-in. in dia- 

meter, with the inlet from the dosing chamber at one end of the mani- 

fold. The inverts of the laterals are perforated with l/4-in. holes 

spaced every 30 in. 

Example 7-3: Design of a Pressure Distribution Network for a Mound 

Design a pressure distribution network for the mound designed in Example 

7-l. 

292

Step 1: 

Step 2: 

Step 3: 

Step 4: 

Step 5: 

Select lateral length. 

IS used in this example. 

A central manifold (Figure 7-24) design 

Lateral length = y - 0.5 ft (for manifold) 

= 32 ft 

Select hole diameter and hole spacing for laterals. For this 

example, l/4-in. diameter holes spaced every 30 in. are used, 

although other combinations could be used. 

Select lateral diameter. For l/4-in. hole diameter, 30-in. 

hole spacing, and 32-ft lateral length, Figure 7-28 indicates 

that either a l-l/4-in. or l-l/2-in. diameter lateral could be 

used. The l-l/4-in. diameter is selected for this example. 

Calculate lateral discharge rate. A 2-ft head is to be 

malntalned 1r-1 the lateral. 

For l/4-in. hole at 2 ft of head, Table 7-13 shows the hole 

discharge rate to be 1.04 gpm. 

Number of holes per lateral = 

32-ft lateral length 

2 . S-ft hole spacing 

= 13 

Lateral discharge rate = (13 holes/lateral) x (1.04 gpm/hole) 

= 13.5 gpm/lateral 

Select manifold size. There are to be four laterals (two on 

either side of the center manifold) spaced 3 ft apart. A 

manifold length of less than 5 ft is required (see Figure 7- 

32). 

For four laterals, 13.5 gpm/lateral, and manifold length less 

than 5 ft, Figure 7-29 indicates that a l-l/2-in. diameter 

manifold is required. 

293

FIGURE 7-32 

DISTRIBUTION NETWORK FOR EXAMPLE 7-3 

294

Step 6: Determine minimum dose volume (Figure 7-30). 

With: lateral diameter = l-1/4 in. 

lateral length = 32 ft 

number of laterals = 4 

Then: pipe volume = 2 gal 

Minimum dose volume = x100 gal 

From Table 7-4, for a medium texture sand, 4 doses/day are 

desirable. Therefore, the dose volume is: 

450 gpd 

4 

Step 7: Determine minimum discharge rate. 

= 112 gal/dose 

Minimum discharge rate = (4 laterals) x (13.5 gpm/lateral) 

= 54 gpm 

Step 8: Select proper pump. For this example, assume the dosing tank 

is located 75 ft from the network inlet, the difference in 

elevation between the pump and the inverts of the distribution 

laterals is 7 ft, and a 3-in. diameter delivery pipe is to be 

used. 

Friction loss in 3-in. pipe at 54 gpm (from Table 7-14) 


= 0.58 +$ (0.81 - 0.58) 

= 0.67 ft/lOO ft 

= (0.67 ft/lOO ft) x (75 ft) 

= 0.5 ft 

Elevation head = 7.0 ft 

Pressure to be maintained = 2.0 ft 

Total pumping head = 9.5 ft 

Therefore, a pump capable of delivering at least 54 gpm against 

9.5 ft of head is required. 

295

In summary, the final network design consists of four 32-ft laterals l- 

l/4 in. in diameter (two on each side of a 3-in. diameter center mani- 

fold. The inverts of the laterals are perforated with l/4-in. holes 

spaced every 30 in. 

90 Other Distribution Networks 

Several other distribution network designs are occasionally used, Among 

these are the inverted network and leaching chambers. While users of 

these networks claim they are superior to conventional networks, compre- 

hensive evaluations of their performance have not been made. 

Inverted Network: This network uses perforated pipe with the holes lo- 

cated in the crown rather than near the invert (32). This arrangement 

is designed to provide more uniform distribution of wastewater over a 

large area, and to prolong the life of the field by collecting any set- 

tleable solids passing out of the septic tank in the bottom of the pipe. 

Water-tight sumps are located at both ends of each inverted line to fa- 

cilitate periodic removal of the accumulated solids. 

Leaching Chambers: In place of perforated pipe and gravel for distri- 

bution and storage of the wastewater, this method employs open bottom 

chambers. The chambers interlock to form an underground cavern over the 

soils' infiltrative surface. The wastewater is discharged into the cav- 

ern through a central weir, trough, or splash plate and allowed to flow 

over the infiltrative surface in any direction. Access holes in the 

roof of the chamber allow visual inspection of the soil surface and 

maintenance as necessary. A large number of these systems have been in- 

stalled in the northeastern United States (see Figure 7-33). 

7.2.8.2 Materials 

Three to 4-in. (8- to lo-cm) diameter pipe or tile is typically used for 

nonpressurized networks. Either perforated pipe or 1-ft (30 cm) lengths 

of suitable drain tile may be used. The perforated pipe commonly has 

one or more rows of 3/8- to 3/4-in. (l.O- to 2.0-cm) diameter holes. 

Hole spacing is, ,not critical. Table 7-15 can be used as a guide for 

acceptable materials for nonpressurized networks. 

Plastic pipe is used for pressure distribution networks because of the 

ease of drilling and assembly. Either PVC Schedule 40 (ASTM D 2665) or 

ABS (ASTM 2661) pipe may be used. 

296

TABLE 7-15 

PIPE MATERIALS FOR NONPRESSURIZED DISTRIBUTION NETWORKS 

Type of Material 

Clay Drain Tile 

Clay Pipe 

Standard and Extra- 

Strength Perforated 

Bituminized Fiber Pipe 

Homogeneous 

Perforated 

Laminated-Wall 

Perforated 

Concrete Pipe 

Perforated Concrete 

Plastic 

Acrylonitrile- 

Butadiene- 

Styrene (ABS) 

Specification 

ASTM C-4 

ASTM C-211 

ASTM D-2312 

ASTM D-2313 

ASTM C-44 (Type 1 ASTM C-14a 

or Type 2) 

ASTM D-2751b 

Polyvinyl ASTM D-2729b 

Chloride (PVC) D-3033b D-3034b 

Styrene-Rubber 

Plastic (SRI 

Polyethylene (PE) 

o Straight Wall 

o Corrugated (Flexible) 

ASTM D-2852b 

D-3298b 

ASTM D-1248b 

ASTM F-405-76b 

a Must be of quality to withstand sulfuric acid. 

Class 

Standard Drain Tile 

Standard 

b These specifications are material specifications only. They do not 

give the location or shape of perforations. 

297


FIGURE 7-33 

SCHEMATIC OF A LEACHING CHAMBER 

Fresh Air 

Vent/ 

a. Gravity Network Pipe Placement 

To insure a free flow of wastewater, the distribution pipe should be 

laid level or on a grade of 1 in. to 2 in. per 100 ft (8.5 to 16.9 

cm/100 m). To maintain a level or uniform slope, several construction 

techniques can be employed. In each case a tripod level or transit is 

used to obtain the proper grade elevations. Hand levels are not 

adequate. 

298

The rock is placed in the excavation to the elevation of the pipe in- 

vert. The rock must be leveled by hand to establish the proper grade. 

Once the pipe is laid, more rock is carefully placed over the top of the 

pipe. Care must also be taken when flexible corrugated plastic pipe is 

used, because the pipe tends to "float" up as rock is placed over the 

top of the pipe. One method is to employ special holders which can be 

removed once all the rock is in place (see Figure 7-34). 

Metal Holder 

FIGURE 7-34 

USE OF METAL HOLDERS FOR THE 

LAYING OF FLEXIBLE PLASTIC PIPE 

b. Pressure Network Pipe Placement 

Pressure distribution networks are usually fabricated at the construc- 

tion site. This may include drilling holes in distribution laterals. 

The holes must be drilled on a straight line along the length of the 

pipe. This can be accomplished best by using l-in. by l-in. angle iron 

as a straight-edge to mark the pipe. The holes are then drilled at the 

proper spacing. Care must be used to drill the holes perpendicular to 

the pipe and not at an angle. All burrs left around the holes inside 

the pipe should be removed. This can be done by sliding a smaller 

diameter pipe or rod down the pipe to knock the burrs off. 

Solvent weld joints are used to assemble the network. The laterals are 

attached to the manifold such that the perforations lie at the bottom of 

the pipe. 

299

Since the network is pressurized, small elevation differences along the 

length of the lateral do not affect the uniform distribution signifi- 

cantly. However, these variations should be held within 2 to 3 in. (5 

to 8 cm). The rock is placed in the absorption area first, to the ele- 

vation of the distribution laterals. The rock should be leveled by 

hand, maintaining the same elevation throughout the system, before lay- 

ing the pipe. After the pipe is laid, additional rock is placed over 

the pipe. 

c. Distribution Boxes 

If used, distribution boxes should be installed level and placed in an 

area where the soil is stable and remains reasonably dry. To protect 

the box from frost heaving, a 6-in. (15-cm) layer of l/2- to 2-l/2-in. 

(1.2- to 6.4-cm) rock should be placed below and around the sides of the 

box. Solid wall pipe should be used to connect the box with the distri- 

bution laterals. Separate connections should be made for each lateral. 

To insure a more equal division of flow, the slope of each connecting 

pipe should be identical for at least 5 to 10 ft (1.3 to 3.0 m) beyond 

the box. 

7.3 Evaporation Systems 


Two basic types of onsite evaporation systems are in use today: 

1. Evapotranspiration beds (with and without infiltration) 

2. Lagoons (with and without infiltration) 

The advantages of these systems are that they utilize the natural energy 

of the sun and, optionally, the natural purification capabilities of 

soil to dispose of the wastewater. They must, however, be located in 

favorable climates. In some water-short areas where consumptive water 

use is forbidden (e.g., Colorado), they may not be allowed. 

Mechanical evaporators are in the experimental stage, and are not com- 

mercially available. For this reason, they are not included in this 

discussion. 

300

7.3.2 Evapotranspiration and Evapotranspiration/Absorption Beds 

7.3.2.1 Introduction 

Evapotranspiration (ET) beds can be used to dispose of wastewater to the 

atmosphere so that no discharge to surface or groundwater is required. 

Evapotranspiration/absorption (ETA) is a modification of the ET concept 

in which discharges to both the atmosphere and to the groundwater are 

incorporated. Both ET and ETA have been utilized for onsite wastewater 

disposal to the extent that several thousand of these systems are in use 

in the United States (33). 


Onsite ET disposal normally consists of a sand bed with an impermeable 

liner and wastewater distribution piping (see Figure 7-35). The surface 

of the sand bed may be planted with vegetation. Wastewater entering the 

bed is normally pretreated to remove settleable and floatable solids. 

An ET bed functions by raising the wastewater to the upper portion of 

the bed by capillary action in the sand, and then evaporating it to the 

atmosphere. In addition, vegetation transports water from the root zone 

to the leaves, where it is transpired. In ETA systems, the impervious 

liner is omitted, and a portion of the wastewater is disposed of by 

seepage into the soil. 

Various theoretical approaches are used to describe the evaporation 

process. This suggests that there may be some uncertainty associated 

with a precise quantitative description of the process. However, cur- 

rent practice is to limit the uncertainties by basing designs on a 

correlation between available pan evaporation data and observed ET 

rates, thereby minimizing assumptions and eliminating the need to aver- 

age long-term climatic data, References (33)(34)(35) and (36) provide a 

more detailed discussion of the correlation method. 


Onsite systems utilizing ET disposal are primarily used where geological 

limitations prevent the use of subsurface disposal, and where discharge 

to surface waters is not permitted or feasible. The geological condi- 

tions that tend to favor the use of ET systems include very shallow soil 

mantle, high groundwater, relatively impermeable soils, or fractured 

bedrock. ETA systems are generally used where slowly permeable soils 

are encountered. 

301

FIGURE 7-35 

CROSS SECTION OF TYPICAL ET BED 

Pipe (4”) 

Topsoil (Varies O-4") 

Although ET systems may be used where the application of subsurface dis- 

posal systems is limited, they are not without limitations. As with 

other disposal methods that require area-intensive construction, the use 

of ET systems can be constrained by limited land availability and site 

topography. Based on experience to date with ET disposal for year-gound 

single-family homes, approximately 4,000 to 6,000 ft (370 to 560 m 1 of 

available land is typically required. The maximum slope at which an ET 

system is applicable has not been established, but use on slopes greater 

than 15% may be possible if terracing, serial distribution, and other 

appropriate design features are incorporated. 

By far the most significant constraint on the use of ET systems is cli- 

matic conditions. The evaporation rate is controlled primarily by cli- 

matic factors such as precipitation, wind speed, humidity, solar radia- 

tion, and temperature. Recent studies indicate that essentially all of 

the precipitation that falls on an ET bed infiltrates into the bed and 

becomes part of the hydraulic load that requires evaporation (33)(34) 

(37). Provisions for long-term storage of effluent and precipitation in 

ET systems during periods of negative net evaporation, and for subse- 

quent evaporation during periods of positive net evaporation, are expen- 

sive. Thus, the year-around use of nondischarging ET systems appears to 

be feasible only in the arid and semiarid portions of the western and 

southwestern United States where evaporation exceeds precipitation dur- 

ing every month of operation, so that long-term storage capacity is not 

302

equired. ET systems for summer homes may be feasible in the more tem- 

perate parts of the country. For ETA systems, the range of applicabil- 

ity is less well defined, but the soils must be capable of accepting all 

of the influent wastewater if net evaporation is zero for any signifi- 

cant periods of the year. 

In addition to climate and site conditions, the characteristics of 

wastewater discharged to an onsite disposal system may affect its appli- 

cation. For ET disposal, pretreatment to remove settleable and float- 

able solids is necessary to prevent physical clogging of the wastewater 

distribution piping. The relative advantages of aerobic versus septic 

tank pretreatment for ET and ETA systems have been discussed in the 

literature (33)(35)(37)(38). Although each method has been supported by 

some researchers, reports of well-documented, controlled studies indii 

cate that septic tank pretreatment is adequate (33)(34)(37). 


The following factors affect the performance of ET and ETA systems: 

1. Climate 

2. Hydraulic loading 

3. Sand capillary rise characteristics 

4. Depth of free water surface in the bed 

5. Cover soil and vegetation 

6. Construction techniques 

7. Salt accumulation (ET only) 

8. Soil permeability (ETA only) 

As noted previously, climate has a significant effect on the application 

and performance of ET and ETA systems. Solar radiation, temperature, 

humidity, wind speed, and precipitation all influence performance. Since 

these parameters fluctuate from day to day, season to season, and year 

to year, evaporation rates also vary substantially. To insure adequate 

overall performance, these fluctuations must be considered in the 

design. 

The hydraulic loading rate of an ET bed affects performance. Too high a 

loading rate results in discharge from the bed; too low a loading rate 

results in a lower gravity (standing) water level in the bed and ineffi- 

cient utilization. Several researchers noted decreased evaporation 

rates with decreased water levels (33)(34)(35). This problem can be. 

overcome by sectional construction in level areas to maximize the water 

level in a portion of the bed, and by serial distribution for sloping 

sites. 

303

The capillary rise characteristic of the sand used to fill the ET bed is 

important since this mechanism is responsible for transporting the water 

to the surface of the bed. Thus, the sand needs to have a capillary 

rise potential at least as great as the depth of the bed, and yet should 

not be so fine that it becomes clogged by solids in the applied 

wastewater (33). 

Significant seasonal fluctuations in the free water surface are normal, 

necessitating the use of vegetation that is tolerant to moisture ex- 

tremes. A variety of vegetation, including grasses, alfalfa, broad-leaf 

trees, and evergreens, have been reported to increase the average annual 

evaporation rate from an ET bed to above that for bare soil (35). How- 

ever, grasses and alfalfa also result in nearly identical or reduced 

evaporation rates as compared to bare soil in the winter and the spring 

when evaporation rates are normally at a minimum (331134). Similarly, 

top soil has been reported to reduce evaporation rates. Certain ever- 

green shrubs, on the other hand, have been shown to produce slightly 

greater evaporation rates than bare soil throughout the year (33). 

Thus, there are conflicting views on the benefits of cover soil and 

vegetation. 

Although ET system performance is generally affected less by construc- 

tion techniques than most subsurface disposal methods, some aspects of 

ET construction can affect performance. Insuring the integrity of the 

impermeable liner and selecting the sand to provide for maximum capil- 

lary rise properties are typically the most important considerations. 

For ETA systems, the effects of construction techniques are similar to 

those discussed previously with reference to subsurface disposal systems 

in slowly permeable soils. 

Salt accumulation in ET disposal systems occurs as wastewater is evaporated. 

Salt accumulation is particularly pronounced at the surface of 

the bed during dry periods, although it is redistributed throughout the 

bed by rainfall. Experience to date indicates that salt accumulation 

does not interfere with the operation of nonvegetated ET systems (39) 

(40) l For ET systems with surface vegetation, salt accumulation may 

adversely affect performance after a long period of use, although observations 

of ET systems that have been in operation for 5 years indicate 

no significant problems (33). In order to minimize potential future 

problems associated with salt accumulation, the ET or ETA piping system 

may be designed to permit flushing of the bed. 

Since ETA systems utilize seepage into the soil as well as evaporation 

for wastewater disposal, soil permeability is also a factor in the per- 

formance of these systems. Discussion of this factor relative to sub- 

surface disposal systems (Section 7.2) applies here. 

304

Data that,quantitatively describe performance are not available for ET 

or ETA disposal. However, the technical feasibility of nondischarging 

ET disposal has been demonstrated under experimental conditions (33) 

(34). In addition, observations of functioning ET systems indicate that 

adequate performance can be achieved at least in semiarid and arid 

areas. The performance of ETA systems depends primarily on the rela- 

tionship between climate and soil characteristics, and has not been 

quantified. However, the technical feasibility of such systems is well 

accepted. 


ET and ETA systems must be designed so that they are acceptable in per- 

formance and operation. Requirements for acceptability vary. On one 

hand, acceptable performance can be defined for an ET system as zero 

discharge for a specified duration such as 10 years, based on the wea- 

ther data for a similar period. Alternatively, occasional seepage or 

surface overflow during periods of heavy rainfall or snowmelt may be al- 

lowed. In addition, physical appearance requirements for specific types 

of vegetation and/or a firm bed surface for normal yard use (necessita- 

ting a maximum gravity water level approximately 10 in. [25 cm] below 

the surface) may also be incorporated in the criteria. 

Appropriate acceptance criteria vary with location. For example, occa- 

sional discharge may be acceptable in low-density rural areas, whereas 

completely nondischarging systems are more appropriate in higher density 

suburban areas. Thus, acceptance criteria are usually defined by local 

health officials to reflect local conditions (33). 

Since the size (and thus the cost) of ET and ETA systems are dependent 

on the design hydraulic loading rate, any reduction in flow to those 

systems is beneficial. Therefore, flow reduction devices and techniques 

should be considered an integral part of an ET or ETA system. 

The design hydraulic loading rate is the principal design feature affec- 

ted by the acceptance criteria. Where a total evaporation system is 

required, the loading rate must be low enough to prevent the bed from 

filling completely. Some discrepancy in acceptable loading rates has 

been reported. Although reports of system designs based on higher load- 

ing rates have been presented in the literature (35)(37), other data 

obtained under controlled conditions indicate that pan evaporation must 

exceed precipitation in all months of a wet year (based on at least 10 

years of data) if a total, year-round evaporation system is usfd. Under 

these canditions, loading rates between 0.03 and 0.08 gpd/ft (1.2 and 

3.3 l/m /day) were found to be appropriate in western states (Colorado 

and Arizona) (33)(34). 

305

The hydraulic loading rate is determined by an analysis of the monthly 

net ET ([pan evaporation x a local factor] minus precipitation) expe- 

rienced in the wettest year of a lo-year period. Ten years of data 

should be analyzed, as very infrequent but large precipitation events 

may be experienced over the life of the system that would result in very 

infrequent discharge. Where occasional discharge from an ET system is 

acceptable, loading rates may be determined on a less restrictive basis, 

such as minimum monthly net ET in a dry year. If the unit is used for 

seasonal application, then only those months of occupancy will consti- 

tute the basis for design. 

The loading rate for ETA systems is determined in the same manner, except 

that an additional factor to account for seepage in the soil is 

included. Thus, the loading rate for an ETA system is generally greater 

than the loading rate for an ET system in the same climate. The available 

data indicate that ETA systems can be used with a wider ra ge of 

cli atic conditions. For example, if soil can accept 0.2 gpd/ft 

h 

9 (8.1 

l/m /day), and the minimum monthly net ET is zero (determined as necessary 

according to 

is also 0.2 gpd/ft 

he accep nce criteria), 

t 

(8.1 l/ 9 /day). 

the loading rate for design 

In addition to loading rates, the designer must also consider selection 

of fill material, cover soil, and vegetation. The role of vegetation in 

providing additional transpiration for ET systems is uncertain at this 

time. During the growing season, the impact of vegetation could be 

significant. However, during the nongrowing season, the effect of vegetation 

has not been well documented. Sand available for ET and ETA bed 

construction should be tested for capillary rise height and rate before 

one is selected. In general, clean and uniform sand in the size of D 

= 0.1 

(33). 

mm (50% by weight smaller than or equal to 0.1 mm) is desirab 7 ! 

The assumptions for a sample ET bed design are given below: 

1. Four occupants of home 

2. 45-gpcd design flow (no in-home water reduction) 

3. Location: Boulder, Colorado 

4. Critical months: December 1976 (see Figure 7-36) 

5. Precipitation: 0.01 in./day (0.25 mm/day) 

6. Pan evaporation: 0.07 in./day (1.7 mm/day) 

An ET bed must be able to evaporate the household wastewater discharged 

to it as well as any rain that falls on the bed surface. Thus, the 

design of an ET system is based on the estimated flow from the home and 

the difference between the precipitation rate and the evaporation rate 

306

FIGURE 7-36 

CURVE FOR ESTABLISHING PERMANENT HOME LOADING RATE FOR BOULDER, COLORADO 

BASED ON WINTER DATA, 1976-1977(33) 

10 

mm/day w 

5 

. 

Pan Evaporation 

J JJ DJ JJ 

1976 1977 

307

during the critical months of the year. In this example, we are assum- 

ing an average household flow of 4 persons x 45 gcpd, or 180 gpd 

total. Past work has shown that actual evaporation from an ET system is 

approximately the same as the measured pan evaporation rate in winter 

(33). Summer rates are approximately 70% of the measured pan evapora- 

tion rates in this area, but excessive evaporation potential more than 

offsets this condition. Therefore, the design is based on pan evapora- 

tion (in./day) minus precipitation (in./day). In this example, 

(0.07 in./day) - (0.01 in./day) = 0.06 in./day 

This equates to a rate of 0.04 gpd/ft2. 

In this example, then, the required area for the ET bed is finally cal- 

culated: 

180 gpd 

0.04 gpd/ft 

2 = 4,500 ft2 

To allow a factor of safety, the size could be increased to as much as 

7,500 ft2 based on 75 gpcd. A more realistic size would be 5,000 to 

6,000 ft', which would insure no overflows. If water conservation is 

practiced, 

achieved. 

direct significant savings in size and costs could be 


A typical ET bed installation was shown previously in Figure 7-35. 

Characteristics of an ETA bed are identical except that the liner is 

omitted. Limited data are available on optimum construction features 

for ET and ETA disposal units. The following construction features are 

desirable: 

1. Synthetic liners should have a thickness of at least 10 mil; it 

may be preferable to use a double thickness of liner material 

so that the seams can be stagoered if seams are unavoidable. 

2. Synthetic liners should be cushioned on both sides with layers 

of sand at least 2 in. (5 cm) thick to prevent puncturing dur- 

ing construction. 

3. Surface runoff from adjacent areas should be diverted around 

the system by berms or drainage swales. 

308

4. Crushed stone or gravel placed around the distribution pipes 

should be 3/4 to 2-l/2 in. (2 to 6 cm). 

5. Filter cloth or equivalent should be used on top of the rock or 

gravel to prevent sand from settling into the aggregate, thus 

reducing the void capacity. 

6. Care should be exercised in assembling the perforated distri- 

bution pipes (4 in. [lo cm]) to prevent pipe glues and solvents 

from contacting the synthetic liner. 

7. The bed surface should be sloped for positive drainage. 

8. A relatively porous topsoil, such as loamy sand or sandy loam, 

should be used if required to support vegetation to prevent 

erosion, or to make the appearance more acceptable. 

9. The bed should be located in conformance with local code re- 

quirements. 

10. Construction techniques described previously for subsurface 

disposal systems, where soil permeability may be decreased by 

poor construction practices, should be used for ETA systems 

(39) (40) (41). 


Routine operation and maintenance of an ET or ETA disposal unit consists 

only of typical yard maintenance activities such as vegetation trimming. 

Pretreatment units and appurtenances require maintenance as described in 

Chapter 8. Unscheduled maintenance requirements are rare, and stem 

mainly from poor operating practices such as failure to pump out septic 

tank solids. 



ET systems may be applicable to small housing clusters and commer- 

cial/institutional establishments, but large area requirements may limit 

their practicality. Adjustments in the type of pretreatment used may be 

required depending on the wastewater characteristics. For example, a 

grease trap is normally required prior to septic tank or aerobic treat- 

ment of restaurant wastewater disposed of in an ET system. 

309

7.3.3 Evaporation and Evaporation/Infiltration Lagoons 


Lagoons have found widespread application for treatment of municipal 

wastewater from small communities, and have occasionally been used for 

wastewater treatment in onsite systems prior to discharge to surface 

waters. A more common application in onsite systems has been for treat- 

ment and subsequent disposal by evaporation, or a combination of evapo- 

ration and infiltration. 

A discussion of evaporation and evaporation/infiltration lagoons is pro- 

vided, since thousands are currently in use across the United States. 

However, performance data are very limited. The information provided in 

this section is based on current practice without assurance that such 

practice is optimal. 


In the United States, an evaporation or evaporation/infiltration lagoon 

could be used in most locations that have enough available land. How- 

ever, local authorities typically prefer or require the use of subsur- 

face disposal systems where conditions permit. Thus, actual application 

of these lagoons is generally limited to rural areas where subsurface 

disposal is not possible. In addition, use of evaporation/infiltration 

lagoons is not appropriate in areas where wastewater percolation might 

contaminate groundwater supplies, such as in areas of shallow or crev- 

iced bedrock, or high water tables. Use of both types of lagoons, espe- 

cially evaporation lagoons, is favored by the large net evaporation po- 

tentials found in arid regions. 

Data on the impact of influent wastewater characteristics on evaporation 

and evaporation/infiltration lagoons are very limited. Pretreatment is 

desirable, especially if a garbage grinder discharges to the system. 


The major climatic factors affecting performance of evaporation and 

evaporation/infiltration lagoons include sunlight, wind circulation, 

310

humidity, and the resulting net evaporation potential. Other features 

that affect performance include: 

1. Soil permeability (evaporation/infiltration only)--lagoon size 

and soil permeability are inversely proportional 

2. Salt accumulation (evaporation only)--results in decreased 

evaporation rate 

3. Hydraulic loading--size must accommodate peak flows 

4. Inlet configuration-- center inlet tends to improve mixing and 

minimize odors 

5. Construction techniques 


Lagoons can be circular or rectangular. The maximum wastewater depth is 

normally 3 to 5 ft (0.9 to 1.5 m) with a freeboard of 2 or 3 ft, (0.6 to 

0.9 m), although depths greater than 8 ft (2.4 m) have also been used 

(42)(43)(44)(45)(46)(47). The minimum wastewater depth is generally 2 

ft (0.6 m). This may necessitate the addition of fresh water during 

high-evaporation summer months. Figure 7-37 shows the dimensional re- 

qujrements for a typical fnsite lagoon. The size ranges from 3 to 24 

ft /gpcd (0.07 to 0.57 m /lpcd), depending primarily on the type of 

lagoon (evaporation or evaporation/infiltration), soil permeability, 

climate, and local regulations. 

Lagoon design is usually based on locally available evaporation and pre- 

cipitation data, soil percolation rates (evaporation/infiltration only), 

and an assumed wastewater flow. Since runoff is excluded by the con- 

tainment berms, evaporation lagoons need only provide adequate surface 

area to evaporate the incident precipitation and the influent waste- 

water. Calculations may be made initially on an annual basis, but must 

then be checked to insure that adequate volume is provided for storage 

during periods when liquid inputs exceed evaporation. A brief design 

example is outlined below. 

Assumptions: 

1. Four occupants of home 

2. 45-gpcd wastewater flow 

3. Annual precipitation: 15.3 in. 

4. Annual evaporation: 46.7 in. 

311

FIGURE 7-37 

TYPICAL EVAPORATION/INFILTRATION LAGOON FOR SMALL INSTALLATIONS 

Inlet4 

312

Design flow: 

Net evaporation per year: 

4 persons x 45 gpcd = 180 gpd 

46.7 in. - 15.3 in. = 31.4 in. 

(31.4 in.)(l44 in.2) = 4,522 in.3 of water/ft2 water surface 

(4,522 in.3)(ft3/1,728 in.3)(7.48 gal/ft3) = 19.6 gal of water/ft2 

water surface 

Lagoon area required: 

(180 gpd)(365 days)/(19.6 gal/ft') = 3,352 ft2 

This can be provided by a round lagoon, 65.3-ft diameter. 

At this point, we need to ensure that the lagoon will have adequate 

storage capacity to allow accumulation of water to a depth of no more 

than 4 or 5 ft in low-evaporation months (usually winter), and to allow 

sufficient surface area for evaporation of the accumulated water plus 

new influent flows during the months when evaporation rates exceed the 

monthly wastewater flow (usually summer). This is done by comparing the 

wastewater flow against the evaporation rate for each months, and by 

performing a water balance (i.e., calculating the gain or loss in gal- 

lons for each months). Table 7-16 shows such a balance. 

From October.through April, the lagoon will gain 35,443 gal of volume. 

This is equivalent to a gain of 1.4 ft: 

(35,443 gal) ( 

Beginning with a 2-ft minimum depth, the depth of the lagoon varies from 

2 ft to 3.4 ft. 

Some sources indicate that BOD loadings should also be considered in 

lagoon sizing for odor control. Loadings in the range of 0.25 to 0.8 

#BOD/day/l,OOO ft2 (1.2 to 3.9 kg/day/1000 m2) have been recommended, 

but supporting data for onsite systems are not available (43)(45)(46). 

If infiltration is permitted and feasible considering local soils, the 

size of the lagoon can be reduced by the amount of water lost through 

percolation. 

313

October 

November 

December 

January 

February 

March 

W April 

w 

P May 

June 

July 

August 

September 

Month Infl uent 

gal 

5580 

5400 

5580 

5580 

5040 

5580 

5400 

5580 

5400 

5580 

5580 

5400 

65/00 

TABLE 7-16 

SAMPLE WATER BALANCE FOR EVAPORATION LAGOON DESIGN 

Precipitationa Netb Cum. 

Precip. Evap. -Evaporation Flow Volume 

i In. in. gal -m- -TJ-- 

1.1 

1.4 

1.8 

1.6 

::: 

::t 

1.2 

0.8 

0.8 

x-i% 

2.2 

1.8 

1.7 

0.7 

0.9 

1.2 

:-i 

6:l 

9.4 

9.0 

-1.1 - 2299 

-0.4 - 836 

0.1 209 

0.9 1881 

0.7 1463 

0.2 418 

-1.7 - 3553 

-4.1 - 8569 

-4.9 -10241 

-8.6 -17974 

-8.2 -17138 

-4.3 - 8987 

a [Precip. - Evap. (gal)] = [Precip. - Evap. (in.)] x (3352 ft2) x (7.48 gal/ft3) x (l/12) 

= 2090 x [Precip. - Evap. (in.)] 

b Net Flow = (Influent) + (Precip. - Evap.) 

3281 3281 

4564 7845 

5789 13634 

7461 21095 

6503 27598 

5998 33596 

1847 35443 

- 2989 32454 

- 4841 27613 

-12394 15219 

-11558 3661 

- 3587 74

Other design features which are frequently incorporated include fencing, 

center inlet, specific berm slopes, and buffer zones. Five- or 6-ft 

(1.5- to 1.8-m) high fencing is preferred to limit animal and human in- 

trusion. Submerged center inlets are recommended to facilitate mixing, 

to provide even solids deposition, and to minimize odors. Interior berm 

slopes, steep enough to minimize rooted aquatic plant growth in the 

lagoon, but resistant to erosion, are desirable. Slopes sufficient to 

accomplish this objective have been reported to be between 3:l and 2:1, 

depending primarily on height and soil characteristics. Buffer zones 

are normally controlled by local regulations, but typically range from 

100 to 300 ft (30 to 91 m). 


To prevent seepage through the berm in unlined lagoons, a good interface 

between the berm and the native soil is necessary. In areas where the 

use of subsurface disposal systems is restricted due to slowly permeable 

soils, B-horizon soils are frequently appropriate for berm construction. 

Excavation of the topsoil prior to berm placement (so that the base of 

the berm rests on the less permeable subsoils) reduces the incidence of 

seepage, as does compaction of the berm material during placement. For 

evaporation lagoons, care during construction to insure placement of a 

leak-free liner reduces the need for impermeable berm material and asso- 

ciated construction precautions. 


Start-up of a lagoon system requires filling the lagoon from a conven- 

ient freshwater source to a depth of at least 2 ft (0.6 m). This ini- 

tial filling helps to prevent rooted plant growth and septic odors. 

Solids removal is required periodically for evaporation lagoons. Data 

are not available to indicate the exact frequency of solids removal 

required, but intervals of several years between pump-outs can be anti- 

cipated. 

The reported need for chemical addition to control odors, insects, 

rooted plants, and microbial growth varies on a case-by-case basis with 

climate, lagoon location and configuration, and loading rate. Mainte- 

nance of a minimum 2-ft (0.6-m) wastewater depth in the lagoon, and fre- 

quent trimming of vegetation on the berm and in the vicinity of the la- 

goon, are suggested. No other maintenance is required. 

315

7.3.3.7 Seasonal, Multifamily, and Commercial Applications 

Use of evaporation and evaporation/infiltration lagoons for summer homes 

would result in somewhat reduced area requirements per gallon of waste- 

water handled, since storage would not need to be provided during the 

winter months. Otherwise, application of these systems to seasonal 

dwellings is comparable to year-round residences. 

Evaporation and evaporation/infiltration lagoons are also applicable to 

multifamily and commercial applications, although additional ,pretreat- 

ment may be required depending on the wastewater characteristics. 

7.4 Outfall to Surface Waters 

Direct discharge of onsite treatment system effluent is a disposal op- 

tion if an appropriate receiving water is available and if the regula- 

tory agencies permit such a discharge. The level of treatment required 

varies, depending on local regulations, stream water quality require- 

ments, and other site-specific conditions. In general, onsite treatment 

system effluent disposed by surface discharge must at least meet secon- 

dary treatment standards for publicly owned treatment works. Depending 

on site-specific conditions, more stringent BOD and SS discharge re- 

quirements and/or limitations on N and P discharges may be applicable. 

The performance, operation, and maintenance requirements, and the en- 

vironmental acceptability of the surface discharge depend predominantly 

on the preceding treatment system. Operation and maintenance associated 

specifically with the surface discharge pipe are minimal in a gravity 

situation. If the effluent must be pumped, then routine pump mainte- 

nance will be required. 

Discharge pipes should be made of corrosion- and crush-resistant materi- 

als such as cast iron or rigid plastic pipe. For single-family systems, 

the pipe should range from 2 to 4 in. (5 to 10 cm) in diameter, should 

be buried, and should be moderately sloped (between 0.5 and 3%). Steep 

slopes may cause washout at the discharge point. 


1. Bendixen, T. W,, M. Berk, J. P. Sheehy, and S. R. Weibel. Studies 

on Household Sewage Disposal Systems, Part II. NTIS Report No. PB 


PP* 

316

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

Bouma, J. Unsaturated Flow During Soil Treatment of Septic Tank 

Effluent. J. Environ. Eng. Div., Am. Sot. Civil Eng., 101:996-983, 

1975. 

Manual of Septic Tank Practice. Publication No. 526, Public Health 

Service, Washington, D.C., 1967. 92 pp. 


Madison. Management of Small Waste Flows. EPA 600/Z-78-173, NTIS 


Laak, R. Pollutant Loads From Plumbing Fixtures and Pretreatment 

to Control Soil Clogging. J. Environ. Health, 39:48-50, 1976. 

Winneberger, J. H., L. Francis, S. A. Klein, and P. H. McGauhey. 

Biological Aspects of Failure of Septic Tank Percolation Systems; 

Final Report. Sanitary Engineering Research Laboratory, University 

of California, Berkeley, 1960. 

Winneberger, J. T., and J. W. Klock. Current and Recommended Prac- 

tices for Subsurface Waste Water Disposal Systems in Arizona. En- 

gineering Research Center Report No. ERC-R-73014, College of Engi- 

neering Service, Arizona State University, Tempe, 1973. 

Subsurface Wastewater Disposal Regulations. Plumbing Code, Part 

II. Department of Human Services, Division of Health Engineering, 

Augusta, Maine, 1978. 

Weibel, S. R., T. W. Bendixen, and J. B. Coulter. Studies on 

Household Sewage Disposal Systems, Part III. NTIS Report No. PB 


PP* 

Corey, R. B., E. J. Tyler, and M. V. Olotu. Effects of Water Soft- 

ener Use on the Permeability of Septic Tank Seepage Fields. In: 

Proceedings of the Second National Home Sewage Treatment Symposium, 

Chicago, Illinois, December 1977. American Society of Agricultural 

Engineers, St. Joseph, Michigan, 1978. pp. 226-235. 

Machmeier, R. E. Town and Country Sewage Treatment. Bulletin 304, 

University of Minnesota, St. Paul, Agricultural Extension Service, 

1979. 

Otis, R. J., G. D. Plews, and D. H. Patterson. Design of Conven- 

tional Soil Absorption Trenches and Beds. In: Proceedings of the 

Second National Home Sewage Treatment Symposium, Chicago, Illinois, 


Joseph, Michigan, 1978. pp. 86-99. 

317

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

21. 

22. 

23. 

24. 

McGauhey, P. H., and J. T. Winneberger. Final Report on a Study of 

Methods of Preventing Failure of Septic Tank Percolation Systems. 

SERL Report No. 65-17, Sanitary Engineering Research Laboratory, 

University of California, Berkeley, 1965. 33 pp. 

Bendixen, T. W., J. B. Coulter, and G. M. Edwards. Study of Seep- 

age Beds. Robert A. Taft Sanitary Engineering Center, Cincinnati, 

Ohio, 1960. 

Bouma, J., J. C. Converse, and F. R. Magdoff. Dosing and Resting 

to Improve Soil Absorption Beds. Trans. Am. Sot. Civ. Eng., 

17:295-298, 1974. 

Harkin, 3. M., and M. D. Jawson. Clogging and Unclogging of Septic 

System Seepage Beds. In: Proceedings of the Second Illinois Pri- 

vate Sewage Disposal system, Champaign, Illinois, 1977. Illinois 

Department of Public Health, Springfield. pp. 11-21. 

Otis, R. J., J. C. Converse, B. L. Carlile, and J. E. Witty. Ef- 

fluent Distribution. In: Proceedings of the Second National Home 

Sewage Treatment Symposium, Chicago, 11 linois, December 1977. 


1978. pp. 61-85. 

Kropf, F. W., R. Laak, and K. A. Healey. Equilibrium Operation of 

Subsurface Absorption Systems. J. Water Pollut. Control Fed., 

49:2007-2016, 1977. 

Otis, R. J. An Alternative Public Wastewater Facility for a Small 

Rural Community. Small Scale Waste Management Project, University 


Alternatives for Small Wastewater Treatment Systems. EPA 625/4-77- 

011, NTIS Report No. PB 299 608, Center for Environmental Research 

Information, Cincinnati, Ohio, 1977. 

Bendixen, T. W., R. E. Thomas, and J. B. Coulter. Report of a 

Study to Develop Practical Design Criteria for Seepage Pits as a 

Method for Disposal of Septic Tank Effluents. NTIS Report No, PB 

216 931, Cincinnati, Ohio, 1963. 252 pp. 

Winneberger, J. T. Sewage Disposal System for the Rio-Bravo Tennis 

Ranch, Kern County, California. 1975. 

Witz, R. L., G. L. Pratt, S. Vogel, and C. W. Moilanen. Waste Dis- 

posal Systems for Rural Homes. Circular No. AE 43, North Dakota 

State University Cooperative Extension Service, Fargo, 1974. 

Converse, J. C., B. L. Carlile, and G. W. Peterson. Mounds for the 

Treatment and Disposal of Septic Tank Effluent. In: Proceedings 

of the Second National Home Sewage Treatment Symposium, Chicago, 

318

25. 

26. 

27. 

28. 

29. 

30. 

31. 

32. 

33. 

34. 

35. 

36. 

37. 



Converse, J. C. Design and Construction Manual for Wisconsin 

Mounds. Small Scale Waste Management Project, University of Wi s- 

consin, Madison, 1978. 80 pp. 

Soil Conservation Service. Drainage of Agricultural Land. Water 

Information Center, Port Washington, New York, 1973. 430 pp. 

Mellen, W. L. Identification of Soils as a Tool for the Design of 

Individual Sewage Disposal Systems. Lake County Health Department, 

Waukegan, Illinois, 1976. 67 pp. 

Casagrande, L. Electra-Osmotic Stabilization of Soils. J. Boston 

Sot. Civ. Eng., 39:51-82, 1952. 

On-Site Wastewater Management. National Environmental Health Asso- 

ciation, Denver, Colorado, 1979. 108 pp. 

Electra-Osmosis, Inc., Minneapolis, Minnesota. 

Bendixen, T. W., and J. 13. Coulter. Effectiveness at the Distri- 

bution Box. U.S. Public Health Service, Washington, D.C., 1958. 

Sheldon, W. H. Septic Tank Drainage Systems. Research Report No. 

10, Farm Science Agricultural Experiment Station, Michigan State 

University, East Lansing, 1964. 

Bennett, E. R. and K. D. Linstedt. Sewage Disposal by Evaporation- 

Transpiration. EPA 600/Z-78-163, NTIS Report NO. PB 288 588, 

September 1978. 196 pp. 

Rugen, M. A., D. A. Lewis, and I. J. Benedict. Evaporation - A 

Method of Disposing of Septic Tank Effluent. Edwards Underground 

Water District, San Antonio, Texas, (no date). 83 pp. 

Bernhardt, A. P. Treatment and Disposal of Wastewater from Homes 

by Soil Infiltration and Evapotranspiration. University of Toronto 

Press, Toronto, Canada, 1973. 173 pp. 

Pence, H. J. Evaluation of Evapotranspiration as a Disposal System 

for Individual Household Wastes (A Seven-State Test); Draft Report. 

National Science Foundation, Washington, D.C., 1979. 

Lomax, K. M., P. N. Winn, M. C. Tatro, and L. S. Lane. Evapotran- 

spiration Method of Wastewater disposal. UMCEES Ref. No. 78-40, 

University of Maryland Center for Environmental and Estuarine Stud- 

ies, Cambridge, 1978. 42 pp. 

319

38. 

39. 

40. 

41. 

42. 

43. 

44. 

45. 

46. 

47. 

Bernhart, A. P. Return of Effluent Nutrients to the Natural Cycle 

Through Evapotranspiration and Subsoil-Infiltration of Domestic 

Wastewater. In: Proceedings of the National Home Sewage Disposal 

Symposium, Chicago, 11 linois, December 1974. American Society of 

Agricultural Engineers, St. Joseph, Michigan, 1975. pp. 175-181. 

Land Treatment of Municipal Wastewater Effluents. EPA 625/4-76-010, 

NTIS Report No. PB 259 994, Center for Environmental Research 

Information, Cincinnati, Ohio, 1976. 

Jensen, M. E., H. G. Collins, R. D. Burman, A. E. Cribbs, and A. I. 

Johnson. Consumptive Use of Water and Irrigation Water Require- 

ments. Irrigation Drainage Division, American Society of Civil 

Engineers, New York, 1974. 215 pp. 

Priestly, C. H. B., and R. J. Taylor. On the Assessment of Surface 

Heat Flux and Evaporation Using Large-Scale Parameters. Mon. 

Weather Rev., 100:81-82, 1972. 

Witz, R. L. Twenty-Five Years with the Nodak Waste Disposal Sys- 

tem. In: Proceedings of the National Home Sewage Disposal Sympo- 

sium, Chicago, Illinois, December 1974. American Society of Agri- 

cultural Engineers, St. Joseph, Michigan, 1975. pp. 168-174. 

Standards for Designing a Stabilization Lagoon. North Dakota State 

Department of Health, Bismarck, (No date). 3 pp. 

Pickett, E. M. Evapotranspiration and Individual Lagoons. In: 

Proceedings of Northwest Onsite Wastewater Disposal Short Courz, 

University of Washington, Seattle, December 1976. pp. 108-118. 

Standards for Subsurface and Alternative Sewage and Non-Water- 

Carried Waste Disposal. Oregon Administrative Rules, Chapter 340, 

Division 7, May 1978. p 97. 

Hines, M. W., E. R. Bennett, and J. A. Hoehne. Alternate Systems 

for Effluent Treatment and Disposal. In: Proceedings of the Sec- 

ond National Home Sewage Disposal Symposium, Chicago, Illinois, 


Joseph, Michigan, 1978. pp. 137-148. 

Code of Waste Disposal Regulations - Part III. Utah State Depart- 

ment of Health, Sewers and Wastewater Treatment Works, Salt Lake 

City, 1977. 41 pp. 

320


CHAPTER 8 

APPURTENANCES 

This chapter discusses several types of equipment used in onsite waste- 

water treatmenl 

components prev 

1. Grease 

2. Dosing 

3. Flow d 

'disposal systems-that have 'general application to the 

ously presented. The following items are covered: 

traps (or grease interceptors) 

chambers 

version methods 

Grease traps are used to remove excessive amounts of grease that may 

interfere with subsequent treatment. Dosing chambers are necessary when 

raw or partially treated wastewater must be lifted or dosed in large 

periodic volumes. Flow diversion valves are used when alternating use 

of treatment or disposal components is employed. These components are 

described as to applicability, performance, design criteria, construc- 

tion features, and operation and maintenance. 

8.2 Grease Traps 

8.2.1 Description 

In some instances, the accumulation of grease can be a problem. In cer- 

tain commercial/institutional applications, grease can clog sewer lines 

and inlet and outlet structures in septic tanks, resulting in restricted 

flows and poor septic tank performance. The purpose of a grease trap is 

simply to remove grease from the wastewater stream prior to treatment. 

Grease traps are small flotation chambers where grease floats to the 

water surface and is retained while the clearer water underneath is dis- 

charged. There are no moving mechanical parts, and the design is simi- 

lar to that of a septic tank. 

321

The grease traps discussed here are the large., outdoor-type units, and 

should not to be confused with the small grease traps found on some 

kitchen drains. 

8.2.2 Application 

Grease traps are very rarely used for individual homes. Their main ap- 

plication is in treating kitchen wastewaters from motels, cafeterias, 

restaurants, hospitals, schools, and other institutions with large vol- 

umes of kitchen wastewaters. 

Influents to grease traps usually contain high organic loads including 

grease, oils, fats, and dissolved food particles, as well as detergents 

and suspended solids. Sanitary wastewaters are not usually treated by 

grease traps. Wastewaters from garbage grinders should not be dis- 

charged to grease traps, as the high solids loadings can upset grease 

trap performance and greatly increase both solids accumulations and the 

need for frequent pumpout. 

8.2.3 Factors Affecting Performance 

Several factors can affect the performance of a grease trap: wastewater 

temperature, solids concentrations, inlet conditions, retention time, 

and maintenance practices. 

By placing the grease trap close to the source of the wastewater (usual- 

ly the kitchen) where the wastewater is still hot, grease separation and 

skimming (if used) are facilitated. As previously mentioned, high sol- 

ids concentrations can impair grease flotation and cause a solids build- 

up on the bottom, which necessitates frequent pumpout. Flow control 

fittings should be installed on the inlet side of smaller traps to pro- 

tect against overloading or sudden surges from the sink or other fix- 

tures. These surges can cause agitation in the trap, impede grease flo- 

tation, and allow grease to escape through the outlet. Hydraulic load- 

ing and retention time can also affect performance. High loadings and 

short retention times may not allow sufficient time for grease to sepa- 

rate fully, resulting in poor removals. Maintenance practices are im- 

portant, as failure to properly clean the trap and remove grease and 

solids can result in excessive grease buildup that can lead to the dis- 

charge of grease in the effluent. 

322

8.2.4 Design 

Sizing of grease traps is based on wastewater flow and can be calculated 

from the number and kind of sinks and fixtures discharging to the trap. 

In addition, a grease trap should be rated on its grease retention capa- 

city, which is the amount of grease (in pounds) that the trap can hold 

before its average efficiency drops below 90%. Current practice is that 

grease-retention capacity in pounds should equal at least twice the flow 

capacity in gallons per minute. In other words, a trap rated at 20 gpm 

(1.3 l/set) should retain at least 90% of the grease discharged to it 

until it holds at least 40 lb (18 kg) of grease (1). Most manufacturers 

of commercial traps rate their products in accordance with this 

procedure. 

Recommended minimum flow-rate capacities of traps connected to different 

types of fixtures are given in Table 8-1. 

Another design method has been developed through years of field experi- 

ence (31. The following two equations are used for restaurants and 

other types of commercial kitchens: 

1. RESTAURANTS: 

(D) x (GL) x (ST) x (y) x (LF) = Size of Grease Interceptor, gallonsa 

where: 

D = Number of seats in dining area 

GL = Gallons of wastewater per meal, normally 5 gal 

ST = Storage capacity factor -- minimum of 1.7 

onsite disposal - 2.5 

HR ? Number of hours open 

LF = Loading factor -- 1.25 interstate freeways 

1.0 other freeways 

1.0 recreational areas 

0.8 main highways 

0.5 other highways 

2. HOSPITALS, NURSING HOMES, OTHER TYPE COMMERCIAL KITCHENS WITH 

VARIED SEATING CAPACITY: 

(Ml x (GL) x (ST) x (2.5) x (LF) = Size of Grease Interceptor, gallonsa 

where: 

M = Meals per day 

GL = Gallons of wastewater per meal, normally 4.5 

323

Type of Fixture 

Restaurant kitchen 

sink 

Single-compartment 

scullery sink 

Double-compartment 

scullery sink 

2 single-compartment 

sinks 

2 double-compartment 

sinks 

Dishwashers for 

restaurants: 

TABLE 8-l 

RECOMMENDED'RATINGS FOR COMMERCIAL GREASE TRAPS (1) 

Up to 30 gal 

water capacity 

Up to 50 gal 


50 to 100 gal 


Flow 

Rate 

gpm 

15 

20 

25 

25 

35 

15 

25 

40 

Grease 

Retention 

Capacity 

Rating 

lb 

324 

30 

40 

50 

50 

70 

30 

50 

80 

Recommended 

Maximum Capacity 

Per Fixture Connected 

to Trap 

gal 

50.0 

50.0 

62.5 

62.5 

87.5 

50.0 

62.5 

100.0

SC =. Storage capacity factor -- minimum of 1.7 

onsite disposal - 2.5 

LF = Loading factor -- 1.25 garbage disposal & 

dishwashing 

1.0 without garbage disposal 

0.75 without dishwashing 

0.5 without dishwashing 

and garbage disposal 

a Minimum size grease interceptor should be 750 gal 

Thus, for a restaurant with a 75-seat dining area, an 8 hr per day oper- 

ation, a typical discharge of 5 gal (19 1) per meal, a storage capacity 

factor of 1.7 and a loading factor of 0.8, the size of the grease inter- 

ceptor is calculated as follows: 

(75) X (5) X (1.7) x it) x (0.8) = 2,040 gal (7,722 1) 

Other design considerations include: facilities for insuring that both 

the inlet and outlet are properly baffled; easy manhole access for 

cleaning; and inaccessibility of the trap to insects and vermin. 

8.2.5 Construction Features 

Grease traps are generally made of pre-cast concrete, and are purchased 

completely assembled. However, very large units may be field construc- 

ted. Grease traps come in single- and double-compartment versions. 

Figure 8-1 shows a typical pre-cast double-compartment trap (2). 

Grease traps are usually buried so as to intercept the building sewer. 

They must be level, located where they are easily accessible for clean- 

i w , and close to the wastewater source. Where efficient removal of 

grease is very important, an improved two-chamber trap has been used 

which has a primary (or grease-separating) chamber and a secondary (or 

grease-storage) chamber. By placing the trap as close as possible to 

the source of wastewaters, where the wastewaters are still hot, the 

separating grease at the surface of the first chamber can be removed by 

means of an adjustable weir and conveyed to the separate secondary 

chamber, where it accumulates, cools, and solidifies. This decreases 

the requirement for cleaning and allows better grease separation in the 

first chamber. 

325

Removable Slab 

Inlet --CL 

Tee with 

Cleanout Plug 7 

Inlet 1 

Precast Concrete 

Tank 

? 

1 1 

FIGURE 8-l 

DOUBLE-COMPARTMENT GREASE TRAP 

Gas Tight Manhole Frame 

‘and Cover for Traffic 

Duty Anticipated 

-t - - e-m- ’ ---I 7 

I \ I 

f 1 ’ 

I- 

.$f& f--k ’ 4 i 

1 

/ I 

T 

! 

*.. I! cii -q- I r 

--m--m-‘- -- -- J I 

I 

I 

L 

Grade 7 

Too View 

Section 

326 

Manhole Cover 

,-Koncrete Pad 

Plug

The inlet, outlet, and baffle fittings are typically of "T" design with 

a vertical extension 12 in. (30 cm) from the tank floor and reaching 

well above the water line (3). 

To allow for proper maintenance, manholes to finished grade should be 

provided. The manhole covers should be of gas-tight construction and 

should be designed to withstand expected loads. 

A check of local ordinances and codes should always be made before the 

grease trap is designed or purchased. 

8.2.6 Operation and Maintenance 

In order to be effective, grease traps must be operated properly and 

cleaned regularly to prevent the escape of appreciable quantities of 

grease, The frequency of cleaning at any given installation can best be 

determined by experience based on observation. Generally, cleaning 

should be done when 75% of the grease-retention capacity has been 

reached. At restaurants, pumping frequencies range from once a week to 

once every 2 or 3 months. 

8.3 Dosing Chambers 


Dosing chambers are tanks that store raw or pretreated wastewater for 

periodic discharge to subsequent treatment units or disposal areas. 

Pumps or siphons with appropriate switches and alarms are mounted in the 

tank to discharge the accumulated liquid. 

8.3.2 Application 

Dosing chambers are used where it is necessary to elevate the wastewater 

for further treatment or disposal, where intermittent dosing of treat- 

ment units (such as sand filters) or subsurface disposal fields is de- 

sired, or where pressure distribution networks are used in subsurface 

disposal fields. If the dosing chamber is at a lower elevation than the 

discharge point, pumps must be used. If the dosing chamber is at a 

higher elevation, siphons may be used, but only if the settleable and 

floatable solids have been removed from the wastewater stream. 

327

- 

8.3.3 Factors Affecting Performance 

Factors that must be considered in design of dosing chambers are (1) the 

dose volume, (2) the total dynamic head, (3) the desired flow rate, and 

(4) the wastewater characteristics. When pumps are used, they must be 

selected based on all three factors. If raw wastewater with large 

solids is pumped, grinder pumps or pneumatic ejectors must be used. 

Siphons are chosen on the basis of the desired flow rate and their dis- 

charge invert elevations determined from the total dynamic head. Only 

wastewaters free from settleable and flotable solids can be discharged 

by siphons. If corrosive wastewaters such as septic tank effluent are 

being discharged, all equipment must be selected to withstand the cor- 

rosive atmosphere. 

8.3.4 Design 

8.3.4.1 Dosing Chambers with Pumps 

A pumping chamber consists of a tank, pump, pump controls, and alarm 

system. Figure 8-2 shows a cross section of a typical pumping chamber 

used for pumping pretreated wastewater. The tank can be a separate unit 

as shown, or it can have common wall construction with the pretreatment 

unit. 

The tank should have sufficient volume to provide the desired dosing 

volume, plus a reserve volume. The reserve volume is the volume of the 

tank between the high water alarm switch and the invert of the inlet 

pipe. It provides storage during power outages or pump failure. A 

reserve capacity equal to the estimated daily wastewater flow is typi- 

cally used for residential application (4). In large flow applications, 

duplex pump units can be used as an alternative to provide reserve capa- 

city. No reserve capacity is necessary when siphons are used. 

Pump selection is based on the wastewater characteristics, the desired 

discharge rate, and the pumping head. Raw wastewater requires a pump 

with solids-handling capabilities. Grinder pumps, pneumatic ejectors, 

or solids-handling centrifugal pumps are suitable for these applica- 

tions. While pneumatic ejectors may be used in other applications as 

well, submersible centrifugal pumps are best suited where large volumes 

are to be pumped in each dose. 

The pump size is determined from pump performance curves provided by the 

manufacturers. Selection is based on the flow rate needed and the pump- 

ing head. The specific application determines the flow rate needed. 

328

lnfluent 

-- --------_ 

--T-------------- 

FIGURE 8-2 

TYPICAL DOSING CHAMBER WITH PUMP 

Relay in Weather Proof 

Enclosure 

T High Water 

_-_ Alarm Switch 

Reserve Capacity 

After Alarm Sounds 

b 

Level Control Switch 

Shut-Off Level E _ _ _ 

Level 

Control f 

Switch 

over 

,-Hanger Pipe 

for Pump Removal 

,- Quick Disconnect 

Sliding Coupler 

x--c Effluent

The pumping head is calculated by adding the,elevation difference be- 

tween the discharge outlet and the average or low water level in the 

dosing chamber to the friction losses incurred in the discharge pipe, 

The velocity head can be neglected in most applications. 

If the liquid pumped is to be free from suspended solids,. the pump may 

be set on a pedestal. This provides a quiescent zone below the pump 

where any solids entering the chamber can settle, thus avoiding pump 

damage or malfunction. These solids must be removed periodically. 

In cold climates where the discharge pipe is not buried below the frost 

line, the pipe should be drained between doses. This may be done by 

sloping the discharge pipe back to the dosing chamber and eliminating 

the check valve at the pump. In this manner, the pipe is able to drain 

back into the dosing chamber through the pump. The dosing volume is 

sized to account for this backflow. Weep holes may also be used if the 

check valve is left in place. 

The control system for the pumping chamber consists of a "pump off" 

switch, a "pump on" switch, and a high water alarm switch. The pump off 

switch is set several inches above the pump intake. The pump on switch 

is set above the pump off switch to provide the proper dosing volume. 

Several inches above the pump on switch, a high water alarm switch is 

set to alert the owner of a pump malfunction by activating a visual 

and/or audible alarm. This switch must be on a circuit separate from 

the pump switches. 

The switches should withstand the humid and other corrosive atmosphere 

inside the tank. Pump failures can usually be traced to switch failures 

resulting in pump burn out, so high quality switches are a good invest- 

ment. Some types are: 

1. Mercury: Two basic types are available. One is an on-off 

switch sealed within a polyethylene float suspended from the 

top of the chamber by its power cord. Two switches are neces- 

sary to operate the pump (See Figure 8-3). The elevations are 

adjusted individually. Differential switches are also avail- 

able to turn the pump on and off with one switch, but these 

lack the ability to adjust the dosing volume. 

330

FIGURE 8-3 

LEVEL CONTROL SWITCHES 

a) Mercury Float b)Pressure Diaphragm c) Weighted Float 

2. Pressure Diaphragm: The pressure diaphragm switch is a micro- 

switch mounted behind a neoprene diaphragm. The microswitch 

side of the diaphragm is vented to the atmosphere by means of a 

vent tube imbedded in the power cord. The other side is sub- 

merged in the liquid. As the liquid level rijes and falls, the 

pressure on the diaphragm activates the switch (See Figure 8- 

3)* Thus, one switch is sufficient to operate the pump; but 

the differential in liquid levels is usually limited to about 6 

in, although switches with larger differentials can be pur- 

chased. If used in pumping chambers, the vent tube must be 

located outside the pumping chamber or the humid atmosphere in 

the chamber can cause the switch to corrode. 

3. Weighted Float: The switch is mounted above the water with 2 

weights attached to a single cable hanging from the switch (See 

Figure 8-3). When the weights are hanging free, the switch is 

held open; but as the liquid level rises, the weights are 

buoyed up, closing the switch when the second weight is sub- 

merged. The switch is held closed by a magnet; but as the 

331 

-...

liquid level drops, the weights lose their buoyancy and open 

the switch when the bottom weight is exposed. The dosing vol- 

ume can be changed by adjusting the spacing between the floats. 

All electrical contacts and. relays must be mounted outside the chamber 

to protect them from corrosion. Provisions should be made to prevent 

the gases from following the electrical conduits into the control box. 

8.3.4.2 Dosing Chambers with Siphons 

Siphons may be used in place of pumps if the point of discharge is at a 

lower elevation than the outlet of the pretreatment unit. A chamber em- 

ploying siphons consists of only a tank and the siphon. No mechanical 

or electrical controls are necessary, since the siphon operation is 

automatic. A typical siphon chamber is illustrated in Figure 8-4. Two 

siphons may be placed in a tank and automatically alternate, providing a 

simple method of dividing the wastewater flow between two treatment or 

disposal units. 

The design of the dosing chamber is determined by the siphon selected 

and the head against which it must operate. The size of the siphon is 

determined by the average flow rate desired. The manufacturer specifies 

the "drawing depth," or the depth from the bottom of the siphon bell to 

the high water level necessary to activate the siphon (See Figure 8- 

41. The length and width of the chamber are determined by the dosing 

volume desired. 

Siphon capacity is rated when discharging into the open atmosphere. 

Therefore, if the discharge is into a long pipe or pressure distribution 

network, the headlosses must be calculated and the invert at the siphon 

discharge set at that distance above the outlet. For high discharge 

rates or where the discharge pipe is very long, the discharge pipe 

should be one nomimal pipe size larger than the siphon to facilitate air 

venting. 

The siphons may be cast iron or fiberglass. Cast iron siphons are the 

most common. Their advantage is that the bell is merely set on the 

discharge pipe 'so they may be easily removed and inspected. They are 

subject to corrosion, however. Fiberglass siphons do not corrode, but 

because of their light weight, they must be bolted to the chamber floor. 

332

333

8.3.5 Construction 

The tank must be watertight so groundwater does not infiltrate it. 

Waterproofing consists of adequately sealing all joints with asphalt or 

other suitable material. Coating the outside of the tank prevents 

groundwater from seeping into the tank. Asphalt coating the inside and 

outside of steel tanks helps retard corrosion. Application of 4-mil 

plastic to the wet asphalt coating protects the coating when back- 

filling. 

At high water table sites, precautions should be taken so the chamber 

does not float out of position due to hydrostatic pressures on a near- 

empty tank. This is not normally a problem for concrete tanks, but for 

the lighter-weight materials, such as fiberglass, it could present a 

problem. The manhole riser pipe should be a minimum of 24 in. (61 cm) 

in diameter and should extend 6 in. (15 cm) above ground level to keep 

surface-water from entering the chamber. 

If plastic pipe is used for the inlet or discharge, precaution should be 

taken to ensure that the pipe does not break as the backfilled soil 

around the tank settles. A cast' iron pipe sleeve or other suitable 

device can be slipped over the plastic pipe extending from the tank to 

unexcavated soil to provide this protection. 


Little routine maintenance of dosing chambers is required. The tank 

should be inspected periodically, and any solids that accumulate on the 

floor of the tank should be removed. If pumps are used, the system 

should be cycled to observe operation of the switches and pump. If 

siphons are used, the water level in the tank should be noted over a 

period of time to determine if the siphon is operating properly. If the 

siphon is working properly, the water level will fluctuate from the bot- 

tom lip of the siphon bell to several inches above the bell. If the 

water elevation does not change despite water addition, the siphon is 

"dribbling," indicating that the vent tube on the bell requires 

cleaning. 

334

8.4 Flow Diversion Methods for Alternating Beds 


Under some circumstances, it is desirable to divert the wastewater flow 

from one soil absorption area to another to provide long-term alternate 

resting periods (see Chapter 7). Flow diversion may be accomplished by 

the use of commercially available diversion valves (Figure 8-5) or by 

diversion boxes (Figures 8-6 and 8-7). 

FIGURE 8-5 

TYPICAL DIVERSION VALVE 

335 

t Access Cap 

Valve Direction Handle

Hori 

FIGURE 8-6 

TOP VIEW OF DIVERSION BOX UTILIZING A TREATED WOOD GATE 

FIGURE 8-7 

Wood Gate 

SECTION VIEW OF DIVERSION BOX UTILIZING ADJUSTABLE ELLS 

90° Ell in 

zontal Position 

(Own) 

1 

Open 

- 

,90° Eli in 

Inlet 

) 

Nipple 

Vertical Position 

(Closed) 

336 

Closed 

I

8.4.2 Design 

Diversion boxes can be made from conventional distribution boxes. One 

type of diversion box shown in Figure 8-6 uses a treated wood gate to 

divert the flow to the desired outlet pipe (5). 

Another, shown in Figure 8-7, uses 90" ells that can be moved from the 

horizontal to the vertical position to shut off flow. Caps or plugs can 

be used in place of elbows. Elbows, however, provide a freer flow of 

air into the resting system. Insulated covers must be provided with 

diversion boxes when installed in cold climates. 

8.4.3 Construction 

Construction follows manufacturers recommendations or the procedures 

outlined for distribution boxes (Chapter 7). 

8.4.4 Maintenance 

Maintenance of diversion valves involves little more than turning the 

valve at the desired frequency. Any accumulated solids in the diversion 

box or valve should be removed periodically. 


1. Manual of Septic Tank Practice. NTIS Report No. PB 216 240, Public 

Health Service, Washington, D.C., 1967. 92 pp. 

2. Hogan, J. R. Grease Trap Discussion. Plumb Eng., May-June 1975. 

3. HYGI Des ign Manua 1. M. C. Nott ingham Company, Pasadena, California, 

1979. 

4. Converse , J. C. Design and Construction Manual for Wisconsin 

Mounds. Small Scale Waste Management Project, University of 

Wisconsin, Madison, 1978. 80 p. 

5. Machmeier, R. E. Home Sewage Treatment Workbook. Agricultural 

Extension Service, University of Minnesota, St. Paul, 1979. 

337


CHAPTER 9 

RESIDUALS DISPOSAL 

Proper maintenance of onsite treatment systems requires periodic dis- 

posal of residual solids, sludges, or brines. In some areas, finding 

environmentally sound techniques for disposal of these residuals has 

been very difficult. Because of the possible presence of pathogens in 

many of these wastewaters, proper handling and disposal are important 

from a public health perspective. The homeowner's role in residuals 

handling is to ensure that residuals from his system are removed peri- 

odically at the appropriate interval so that proper system performance 

is maintained. 

This chapter discusses the characteristics of residuals, and describes 

treatment and disposal options for septage (septic tank pumpings). The 

chapter is intended to be merely an overview of residuals handling op- 

tions. The reader is referred to publications that discuss particular 

alternatives in greater detail. 

9.2 Residuals Characteristics 

Table 9-l summarizes the residuals that may be generated by onsite 

wastewater handling systems. Typical characteristics, removal frequen- 

cies, and disposal modes are presented. Many of the residuals listed 

may contain significant amounts of pathogenic organisms, nutrients, and 

oxygen-demanding materials; thus, they require proper handling and dis- 

posal to protect public health and to prevent degradation of groundwater 

and surface water quality. 

In general, residuals generated by onsite wastewater systems are highly 

variable in character. This is due to several factors, including type 

and number of fixtures, number and age of occupants, type of wastewater 

treatment system, and user habits. 

The wastewater removed from septic tanks, commonly referred to as sept- 

age, is the most common residual generated from onsite wastewater sys- 

tems. The characteristics of septage are presented in Tables 9-2 and 

9-3. While information on septage characteristics and treatment 

/disposal alternatives is relatively abundant, data on other residuals 

listed in Table 9-l are limited. 

338

Residual 

Septage 

Sludge 

Sewage 

Blackwater 

Recycle 

Residuals 

Compost 

Ash 

Scum 

Source 

Septic tank 

Aerobic unit 

Holding tank 

Holding tank 

Recycle systems 

Compost toilet; 

large 

small 

Incinerator toilet 

Sand filters 

TABLE 9-l 

RESIDUALS GENERATED FROM ON SITE WASTEWATER SYSTEMS 

Frequency of 

Removal 

2 to 5 yr 

1 yr 

week to months 

6 months-l yr 

6 months-l yr 

6 months-l yr 

3 months 

weekly 

6 months 

a Approval by state or local regulatory agency necessary. 


High BOD and SS; odor, 

grease, grit, hair, 

pathogens 

High BOD and SS; 

grease, hair, grit, 

pathogens 

Strong septic sewage; 

odor, pathogens 

High BOD and SS; odor, 

pathogens 

Variable depending on 

unit processes employed 

Relatively stable, high 

organics, low pathogens 

Dry, sterile, low 

volume 

Odor, pathogens, low 

volume 

(1) 

Disposala 

Pump out by professional 

hauler for off-site 

disposal. 



disposal. 



disposal. 



disposal. 

Pump out by profesisonal 


disposal. 

Homeowner performs 

onsite disposal; garden 

burial. 

Onsite burial by 

homeowner or disposal 

with rubbish to landfill 

Onsite burial by 

homeowner or off-site 

disposal

Parameter 

TABLE 9-2 

CHARACTERISTICS OF DOMESTIC SEPTAGE 

Mean Value 

mg/l 

Total Solids 22,400 2 

11,600 

3 

39,500 

4 

Total Volatile Solids 15,180 2 

8,170 

3 

27,600 

4 

Suspended Solids 

Volatile Suspended Solids 

BOD 

COD 

PH 

Alkalinity (CaCO3) 

TKN 

NHj-N 

340 

2,350 

9,500 

21,120 

13,060 

1,770 

7,650 

12,600 

8,600 

4,790 

5,890 

3,150 

26,160 

19,500 

60,580 

24,940 

16,268 

2 

3 

5 

6 

2 

3 

6 

6-7 (typical) 2,3,4 

610 

1,897 

410 

650 

820 

472 

59 

100 

120 

92 

153 

Reference 

3 

5

Parameter 

Total Phosphorus 

Grease 

Aluminum 

Arsenic 

Cadmium 

Chromium 

Copper 

Iron 

Mercury 

Manganese 

Nickel 

Lead 

Selenium 


Mean Value 

w/l 

190 

214 

172 

351 

Reference 

3,850 3 

9,560 4 

48 6 

0.16 6 

0.1 3 

0.2 4 

9.1 6 

0.6 

1.1 

8.7 3 

8.3 6 

210 3 

160 4 

190 6 

0.02 4 

0.4 6 

5.4 4 

4.8 6 

0.4 3 

Cl.0 4 

0.7 6 

2.0 3 

8.4 6 

0.07 6 

Zinc 9.7 3 

62 4 

30 6 

341

Parameter 

Total Coliform 

Fecal Coliform 

Fecal Streptococci 

Ps. aeruginosa 

Salmonella sp. 

Parasites 

Toxacara, Ascaris 

lumbricoides 

Trichuris trichiura, 

Trichuris vulpis 

TABLE 9-3 

INDICATOR ORGANISM 

IN DOMESTIC 

AND PATHOGEN CONCENTRATIONS 

SEPTAGE 

Typical Range 

counts/100 ml 

107 - 109 

106 - 108 

106 - 107 

101 - 103 

(1 - 102 

Present 

Reference 

5 

4,5,7 

4,537 

4,557 

Septage, a mixture of sludge, fatty materials, and wastewater removed 

during the pumping of a septic tank, is a difficult and undesirable 

material to handle. It is often highly odoriferous and may contain 

significant quantities of grit, grease, and hair that may make pumping, 

screening, or settling difficult. Of particular importance is the high 

degree of variability of this material, some parameters differing by two 

or more orders of magnitude. This is reflected to some extent by the 

variability in mean values presented in Table 9-2. For this reason, 

septage should be characterized prior to selection of design values. 

In general, the heavy metal content of septage is low relative to muni- 

cipal wastewater sludge, although the range of values may be wide. 

Because of the low metal content, application rates may be based on 

nitrogen rather than metal loading for land application systems (8). 

Table 9-3 presents typical concentration ranges for indicator organisms 

and pathogens in septage. These values are not unlike those found for 

raw primary wastewater sludge. It is evident that septage may harbor 

disease-causing organisms, thus demanding proper management to protect 

public health. 

342 

435 

5

Accumulation rates of residuals differ for the same reasons that account 

for their variability in characteristics: that is, type and number of 

fixtures, occupancy characteristics, type of wastewater system, user ha- 

bits, etc. The figures presented in Table 9-l for frequency of resid- 

uals removal reflect typical ranges found in practice, although the 

range of actual values may be greater. 

9.3 Residuals Handling Options 

Residuals that potentially may be disposed of onsite by the homeowner 

include compost from compost toilets, ash from incinerating toilets, and 

the solids mat from sand filters. Assuming proper operation of the 

unit, ash from incinerating toilets is sterile and can be safely dis- 

posed by mixing it with soil on the homeowner's property, or by handling 

with household solid wastes. Residuals from compost toilets are rela- 

tively stable, but may contain pathogenic bacteria and virus, especially 

if the system has not been properly operated and maintained. Onsite 

burial is approved in some states but not in others, due to the possible 

health hazards of handling the waste. The same conditions hold for dis- 

posal of the scum that must be periodically raked off filtration units. 

Pathogens may be present in the scum layer, and approval for onsite dis- 

posal varies with locale. The appropriate state or local regulatory 

agency should be consulted for the requirements in a particular area. 

As Table 9-l indicates, the residues from septic tanks, aerobic treat- 

ment units, holding tanks, and recirculating toilets must be periodi- 

cally pumped out and disposed of by professional haulers. The home- 

owner's responsibility should be to ensure that this service is provided 

before residuals buildup impairs performance of the treatment unit. 

9.4 Ultimate Disposal of Septage 

By far the most common waste material generated from onsite systems is 

septage. The following discussion provides a brief overview of tech- 

niques for disposal of this waste. For a more complete description of 

these processes, the reader is referred to the list of references at the 

end of this chapter. 

There are three basic methods for disposing of septage: disposal to 

land, treatment and disposal at separate septage handling facilities, 

and treatment at existing wastewater treatment plants. 

343

9.4.1 Land Disposal 

Four methods can be used for disposing of septage to land: surface 

spreading, subsurface disposal, trenching, and landfilling. Table 9-4 

summarizes the main characteristics of these disposal techniques. 

Land spreading is the most frequently used septage disposal method in 

the United States. Surface spreading of septage is generally accom- 

plished by the same techniques as municipal liquid wastewater sludge 

spreading. This may simply involve the septage pumping truck emptying 

its contents on the field while slowly driving across the site. This 

technique has very low operation and maintenance requirements. A more 

controlled approach is to use a holding tank to receive septage loads 

when the soil is not suitable for spreading. A special vehicle (tractor 

.or truck with flotation tires) can then be used to spread the septage 

when weather and soil conditions permit. 

Subsurface disposal techniques have gained wide acceptance as alterna- 

tives for disposal of liquid sludge and, to some extent, septage. Three 

basic approaches to subsurface disposal are available: 

1. Incorporation using a farm tractor and tank trailer with at- 

tached subsurface injection equipment. 

2. Incorporation using a single, commercially available tank truck 

with subsurface injection equipment. 

3. Incorporation using tractor-mounted subsurface injection equip- 

ment in conjunction with a central holding facility and flex- 

ible "umbilical cord." Liquid sludge is continually'pumped 

from the holding tank to the injection equipment. 

Disposal of septage by burial in excavated trenches is another common 

disposal technique. Trenches are typically 3 to 6 ft (0.9 to 1.8 m) 

deep and 2 to 3 ft (0.6 to 0.9 m) wide, with dimensions varying with 

site location. Space between trenches should be sufficient to allow 

movement of heavy equipment. A series of trenches is usually dug by a 

backhoe to allow sequential loading and maximum dewatering. Septage is 

usually applied.in 6- to 8-in. (15 to 20 cm) layers. When the trenches 

are full, the solids can be excavated and placed in a landfill if they 

have dewatered sufficiently, or the trenches can be covered with 2 ft 

(0.6 ml of soil. A thorough site evaluation is essential to prevent 

groundwater contamination with this disposal technique. 

344

TABLE 9-4 

LAND DISPOSAL ALTERNATIVES FOR SEPTAGE 

Alternative Design Considerations Advantages Disadvantages 

Subsurface Septage volume/characteristics Low human contact potential Large land requirements 

Disposal Climate Low incidence of odors Storage may be required 

[W;“’ Site characteristics and vectors during inclement weather - 

- Soil type/permeability Aesthetically more wet or frozen ground 

(19) - Depth to groundwater acceptable than surface Need more equipment than for 

or bedrock spreading surface spreading 

- Aquifer size? flow Good soil amendment 

characteristics, use 

- Slope 

- Proximity to dwellings, etc. 

- Crop and crop use 

- Size of site 

- Site protection 

Equipment selection 

Application rate 

Winter storage or 

contingency plan 

Monitoring wells 

Surface Septage volume/characteristics 

Spreading Application rate (N loading) 

;;‘,;W;f3’ Climate 

Storage facilities 

(19) Site characteristics (same 

as subsurface disposal) 



Small labor requirement Possible odor and aesthetic 

Minimum equipment required nuisance 

Benefit from fertilizer - Spreading restricted by wet 

soil amendment value or frozen soil 

Low cost Storage may be required 

Simple Operation during inclement weather 

Pretreatment may be required 

for deodorization and 

pathogen destruction 

Possible human contact or 

vector attraction


Alternative Design Considerations Advantages Disadvantages 

Trench Septage volume/characteristics Simple operation Higher potential for 

Disposal Site characteristics Low labor requirement groundwater contamination 

(lH9Hl7) - Soil type/permeability Minimal equipment required Odors and vectors 

(18) - Depth to groundwater or Low cost Limited design life - 

bedrock Less land required than usually cannot use same 

- Aquifer size, flow surface or subsurface land repeatedly 

characteristics, use spreading operations 

- Proximity to dwellings, etc. 

- Proximity to septage sources 

Site protection 


Design life 


Sanitary Septagelrefuse ratio No new equipment needed Limited application due to 

Landfill Leachate collection/treatment Low odor and pathogen leachate generation 

Disposal Monitoring wells problems due to daily Good operating procedures 

(lH9H14) soil cover required - refuse/septage 

Low cost mixing 

Extensive monitoring 

required - leachate, 

runoff, groundwater 

May not be approved in some 

states

Sanitary landfills in the United States generally accept a multiplicity 

of materials such as refuse, industrial wastes, and sometimes hazardous 

or toxic wastes. All of these wastes are compiled on a daily basis at 

the landfill and buried under a soil cover. The acceptance of septage 

at a landfill depends chiefly on the ratio of the mixture of septage to 

refuse to maintain moisture control. However, a few states do not allow 

landfill disposal of septage, and some others do not recommend it be- 

cause of potential runoff and leachate problems. 

9.4.2 Independent Septage Treatment Facilities 

In some areas of the country, facilities have been constructed exclu- 

sively for handling septage. These systems vary from simple holding 

lagoons to sophisticated, mechanically based plants. The latter systems 

are generally more capital intensive, and may also have greater opera- 

tional requirements. Such systems have been found to be cost effective 

in areas of significant septic system density, such as Long Island, New 

York. In rural areas, simpler, less expensive alternatives may be more 

economically favorable. Of the independent facilities listed in Table 

9-5, lagoons are the most common and among the least expensive indepen- 

dent septage handling alternatives. All of the other independent sys- 

tems have been implemented to some degree, although in most cases, not 

widely. 

9.4.3 Septage Handling at Wastewater Treatment Plants 

Two methods exist for handling septage at wastewater treatment facili- 

ties: addition to the liquid stream (near the headworks or upstream 

from the plant), or addition to the solids handling train (see Table 9- 

6). Both have advantages under appropriate conditions. For example, 

addition to the headworks (screens, grit chamber) is desirable where the 

plant employs primary clarification, since this effectively introduces 

the septage solids directly into the sludge handling scheme. For ex- 

tended aeration plants, however, septage addition to the wastewater flow 

may have a severe impact on the aeration capacity of the system. Thus, 

introducing the septage into the sludge stream may be desirable. Con- 

sideration of plant aeration and solids handling capacity is necessary 

to determine whether either scheme is feasible. Under either mode of 

addition, solids production increases with increased septage addition. 

Septage holding facilities allow controlled addition of the septage to 

the wastewater treatment plant. 

For additional information on the capability of wastewater treatment fa.- 

cilities to handle septic tank pumpings, the reader is referred to the 

publications list in Section 9.5 (3)(11). 

347

W 

z 

Process 

Lagooning 

(1)(13)(14) 

(161(17) 

Lime 

Stabilization 

(l)(4)(5) 

Chlorine 

Oxidation 

(1)(9)(15) 

Aerobic 

Digestion 

(1)(9)(13) 

Description 

Usually anaerobic or facultative 

Inlet on bottom for odor control 

Liquid disposal by percolation 

and evaporation in lagoon or by 

separate infiltration bed 

pH adjustment to pH 6-8 may be 

necessary for odor control 

Collection, mixing, and reaction 

with lime to pH 12 (hold 1 hour) 

Dewatering optional 

Odors eliminated, pathogens greatly 

reduced 

Chlorine and septage mixed in 

pressurized reaction chamber 

pH 1.2 - 2.5 

Chlorine dosage 700-3,000 mgfl 

Similar to aerobic diqestion of 

sewage sludge - 

Often accomplished at existinq 

wastewater treatment plant 

TABLE 9-5 

INDEPENDENT SEPTAGE TREATMENT FACILITIES 

Design Considerations 

Septage volume/characteristics 

Site location 

- Distance to dwellings, etc. 

- Depth to qroundwater or 

bedrock 

- Distance to surface water 

Depth of liquid, surface area 

Climate 

Aquifer characteristics 


Solids removal and disposal 

Septaqe volume/characteristics 

Septage receivinq/holdinq 

Mixing (air or mechanical1 

Lime handlinq and feeding 

Final disposal 


Equipment sizinq 

Septage receivinq/holding 

Oewatering facilities 

Final solids disposal 

Chlorine storage/safety 


Seotaqe receiving/holdinq 

Orqnnic loading 

Solids retention time (20-30 

days) 

Climate (temperature) 

Mixino and 00 level 

Final disoosal 

Advantaqes 

Low cost 

Simple operation 

Odor eliminated 

Good pathogen 

reduction 

Low land requirement 

Enhanced solids 

dewatering 

Stable, odor-free 

sludqe produced 

Hiqh DathOqen 

destruction 

Enhanced solids 

dewateri ng 


SS reduction 

ROD reduction 

Reduction of odor and 

pathogens 

May enhance solids 

dewaterina 


Disadvantaaes 

Odor problems if pH not maintained 

Cannot use in areas with hiqh 

water table 

Possible vector orohlem 

Soil cloaqinq may stoo percolation 

No reduction in orqanic matter 

Lime increases auantity for 

ffnal disoosal 

Hloh cost for labor and lime 

Unknown effects of lona-term 

storaqe 

High operatina costs dependent on 

chlorine cost 

Neutralization nray be required 

Question of harmful chlorinated 

orqanics 

Underdrainaqe liquor reauires 

further treatment 

Riolooical oneration not simnle 

Subject to oroanic overloadina 

Reauires monitorina and lab 

analvsis 

Can have foaming Drohlems

Process 

Composting 

(1) 

Anaerobic 

Digestion 

(9)(11) 

Chemical 


(1)(9)(10) 

Dewatering 

(l)(lD) 

Description 

May be natural draft or forced air 

Seotaqe mixed with bulking material 

High temperature/pathogen 

destruction 

Storage/distribution 

Often accomplished in combination 

with sewage sludge 

Demonstrated on pilot-scale 

Identical to sludge digestion 

technology 

Chemical coagulation 

- Mixing and settling 

- Supernatant 

treatment/disposal 

collection, 

- Sludge holding/dewatering/disposal 

Acidification (H2SD41 

- Mixing and settling 

- Additional coagulation possible 

with lime 

Drying beds 

Pressure filtration 

Vacuum filtration 

Drying lagoons 

Centrifugation 



Seotaqe volume/characteristics 

Septage receiving/holding 

Bulking agent availability 

Dewatering 

Materials handling capabilitv 


Septage receiving/holding 

Grit removal 

Solids retention time 

Maintenance of digester 

temperature 

No toxic materials inout 



Seotage receiving/holdino 

Chemical feed eauioment and 

dose levels 

Mixinq, 

time 

reaction time, settlinq 



Septage receivinq/holdinq 

SS concentrations 

Filterability 

Pretreatment-chemical 

conditioning 


Advantages 

Provides pathogen 

destruction and 

stabilization 

Produces soil 

amendment 

Operationally simole 

Low energy 

requirements 

Methane recovery/ 

utilization 

possible 

Stahilized prOdUCt 

Can handle variety of 

oraanic wastes 

Disadvantaqes 

High bulking apent reouirement if 

not dewatered 

Product market must be established 

May he labor-intensive 

Bioloaical process reouires close 

ooerator control 

Suh,ject to upset bv toxics 

Reauires continuous supply of 

organic materials 

Low land reauirement Hinh labor reouirement 

Hioh costs 

Reduced hauling costs 

Reduces area required 

for disposal 

Hiah cost for some alternatives 

Hiqh operation and maintenance 

requirements 

Mechanical dewaterina devices 

require an enclosure

Process Description 

Liouid Stream Seotaqe placed in storage tank at 

Addition plant 

(31(61(11)(121 Pretreatment (screening, grit 

removal) 

Controlled bleed into headworks to 

prevent shock overload 

Sludge Stream Septage placed in storage tank 

Addition Fed directly into sludge stream with 

(61(11)(121 or without separate conditioning/ 

handling 

TABLE 9-6 

SEPTAGE TREATMENT AT WASTEWATER TREATMENT PLANTS 



Plant capacity (aeration and 

solids handlinql 

Receiving station 

- Truck 

- Storage 

transfer 

- Pretreatment (optional 1 

- Controlled discharqe to plant 

Sludge production 

O&M (power, labor, chemicals) 


Septage receiving/holdino 

Organic and solids loading on 

each sludqe handling unit 

Pumping and storage capacity 

Additional mixing and feeding 

equipment 

Increase in chemical usaae 

Advantaqes bisadvantaaes 

Easily implemented 

Low capital cost 

Public 

qood 

acceptance 

Particularly 

desirable at olants 

with orimary 

clarification 

Avoids overloading 

secondary and 

tertiary systems 

Avoids oossi hility of 

final effluent 

deqradation 

Additional sl udqe neneration 

MAV oraanicallv overload olant 

Increa&d fMV_ 

Final disposal site and sludae 

eauioment 

needed 

exoansion may he 

Additional sludqe oeneratinn 

Final disposal site and sludoe 

eauipment exoansion way he 

needed


1. Bowker, R. P. G., and S. W. Hathaway. Alternatives for the Treat- 

ment and Disposal of Residuals from On-Site Wastewater Systems. 

Municipal Environmental Research Laboratory, Cincinnati, Ohio, 

1978. 

2. Kolega, I. J., A. W. Dewey, B. J. Cosenza, and R. L. Leonard. 

Treatment and Disposal of Wastes Pumped from Septic Tanks. EPA 

600/Z-77-198, NTIS Report No. PB 272 656, Storrs Agricultural 

Experiment Station, Connecticut, 1977. 170 pp. 

3. Segall, B. A., C. R. Ott, and W. B. Moeller. Monitoring Septage 

Addition to Wastewater Treatment Plants, Volume I: Addition to the 

Liquid Stream. EPA 600/Z-79-132, NTIS Report No. PB 80-143613, 

1979. 

4. Feige, W. A., E. T. Oppelt, and J. F. Kreissl. An Alternative 

Septage Treatment Method: Lime Stabilization/Sand-Bed Dewatering. 

EPA 600/Z-75-036, NTIS Report No. PB 245 816, Municipal Environ- 

mental Research Laboratory, Cincinnati, Ohio, 1975.~ 64 pp. 

5. 

6. 

7. 

8. 

9. 

10. 

Noland, R. F., J. D. Edwards, and M. Kipp. Full Scale Demonstration 

of Lime Stabilization. EPA 600/Z-78-171, NTIS Report No. PB 286 

937, Burgess and Niple Ltd., Columbus, Ohio, 1978. 89 pp. 

Bennett, S. M., J. A. Heidman, and J. F. Kreissl. Feasibility of 

Treating Septic Tank Waste by Activated Sludge. EPA 600/Z-77-141, 

NTIS Report No. PB 272 105, District of Columbia, Department of 

Environmental Services, Washington, D.C., 1977. 71 pp. 

Deninger, J. F. Chemical Disinfection Studies of Septic Tank 

Sludge with Emphasis on Formaldehyde and Glutaraldehyde. M.S. 

Thesis. University of Wisconsin, Madison, 1977. 

Maine Guidelines for Septic Tank Sludge Disposal on the Land. 

Miscellaneous Report 155. Life Sciences and Agriculture Experiment 

Station and Cooperative Extension Service, University of Maine, 

Orono, Maine Solid and Water Conservation Commission, 1974. 

Cooper, I. A., and J. W. Rezek. Septage Treatment and Disposal. 

Prepared for the EPA Technology Transfer Seminar Program on Small 

Wastewater Treatment Systems, 1977. 43 pp. 

Condren, A. J. Pilot Scale Evaluations of Septage Treatment 

Alternatives. EPA 600/Z-78-164, NTIS Report No. PB 288 415, Maine 

Municipal Association, Augusta, Maine, 1978. 135 pp. 

351

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

Bowker, R. P. G. Treatment and Disposal of Septic Tank Sludges. A 

Status Report. May 1977. In: Small Wastewater Treatment Facili- 

ties. Design Seminar Hand?%jt. Environmental Protection Agency 

Technology Transfer, Cincinnati, Ohio, 1978. 

Cooper, I. A., and J. W. Rezek. Septage Disposal in Wastewater 

Treatment Plants. In: Individual On-Site Wastewater Systems. Pro- 

ceedings of the Third National Conference. N. McClelland, ed. Ann 

Arbor Science, Ann Arbor, Michigan, 1977. pp. 147-169. 

Jewell, J. W., J. B. Howley, and D. R. Perrin. Design Guidelines 

for Septic Tank Sludge Treatment and Disposal. Prog. Water Tech- 

nol., 7, 1975. 

Guidelines for Septage Handling and Disposal. New England Inter- 

state Water Pollution Control Commission, Boston, Massachusetts, 

August 1976. 

Wise, R. H., T. A. Pressley, and B. M. Austern. Partial Charac- 

terization of Chlorinated Organics in Superchlorinated Septages 

and Mixed Sludges. EPA 600/Z-78-020, NTIS Report No. PB 281 529, 

USEPA, MERL, Cincinnati, Ohio, 1978. 30 pp. 

Brown, D. V., and R. K. White. Septage Disposal Alternatives for 

Rural Areas. Research Bulletin 1096, Ohio State University, 

Columbus, 1977. 

Barlow, Gill and E. Allan Cassell. Technical Alternatives for 

Septage Treatment and Disposal in Vermont. Draft. Vermont Water 

Resources Research Center, University of Vermont,.Burlington, 1978. 

Walker, J. M., W. D. Burge, R. L. Chaney, E. Epstein, and J. D. 

Menzies. Trench Incorporation of Sewage Sludge in Marginal Agri- 

cultural Land. EPA 600/Z-75-034, NTIS Report No. PB 246 561, 

Agricultural Research Service, Beltsville, Maryland, 1975. 252 pp. 

Sommers, L. E,, R. C. Fehrmann, H. L. Selznick, and C. E. Pound. 

Principles and Design Criteria for Sewage Sludge Application on 

Land. In: Sludge Treatment and Disposal Seminar Handout, Environ- 

mental Research Information Center, Cincinnati, Ohio, 1978. 

352


CHAPTER 10 

MANAGEMENT OF ONSITE SYSTEMS 

Onsite systems offer a viable means for controlling public health haz- 

ards, environmental degradation, and nuisances that might otherwise 

arise from wastewater generated in unsewered areas. If onsite systems 

are to perform successfully over a reasonable lifetime, a sound manage- 

ment program with sufficient technical assistance and enforcement cap- 

abilities is needed. 

Management programs may take many forms. A good program, at a minimum, 

performs the following functions: 

1. Site evaluation validation 

2. System design review 

3. Construction supervision 

4. Operation and maintenance certification 

5. Rehabilitation assistance 

76: 

Monitoring and enforcement 

Public education activities 

Most states perform some or all of these functions with much of the 

responsibility often delegated to local units of government. These 

programs are very diverse (1). At one end of the spectrum, the state 

may limit its responsibility to the promulgation of minimum standards to 

be adopted by local jurisdictions, which may have the right to establish 

stricter standards. At the other end, the state may retain all 

management functions over onsite systems. 

Thus, the management programs used in various jurisdictions differ 

greatly as do their effectiveness. Therefore, the following examination 

of approaches and techniques that may be used to manage onsite systems 

is intended to: 

1. Provide a means of evaluating the existing management program. 

2. Suggest techniques used to improve an existing management pro- 

gram or to establish a new one. 

353

Some of the techniques discussed may not be.readily incorporated into 

existing management programs due to different state constitutional and 

statutory provisions and legal interpretations. Some techniques may 

require the enactment of enabling legislation granting the management 

entity necessary authority to manage onsite systems. 

10.2 Theory of Management 

An effective management program provides technical assistance together 

with strong regulation enforcement. Both aspects are directed at major 

control points. 

10.2.1 Principal Control Points 

There are several distinct phases in the life of an onsite system that 

require control. These are: 

1. Installation 

2. Operation 

3. Maintenance 

During the "installation" phase, the management program must limit 

installation to suitable sites, and assure the proper design and 

construction of all onsite systems. It is during this phase that 

management programs can be most effective in minimizing the potential 

threat to public health and water quality. 

During the "operation" phase, the management program must assure proper 

operation of an onsite system through periodic monitoring. While there 

are very few operational requirements for a septic tank-soil absorption 

system, some of the onsite systems have more extensive requirements. A 

good management program imposes controls during this phase whether the 

system's operation is straightforward or elaborate. 

Finally, in the "maintenance" phase, the management program must provide 

for adequate maintenance of an onsite system, e.g., periodic pumping of 

septic tanks. It also must detect any onsite system that fails to func- 

tion properly. This may be done through systematic or random inspec- 

tions. A good program takes the necessary action to assure that repair, 

replacement, or abandonment of failed systems is completed. 

354

10.2.2 Authority Needed by Management Entities 

If adequate management is to be provided at the principal control 

points, management entities should have the authority to perform the 

functions listed below. The optional functions become imperative if the 

management entities own the onsite systems. 

Suggested Functions Optional Functions 

1. Site evaluation 1. Planning 

2. System design 2. Legal functions 

3. Installation 3. Financing 

4. Operation and Maintenance 4. Public education 

5. Rehabilitation 

6. Monitoring 

The authority to perform.these functions does not need to be granted to 

a single management entity. In fact, it is unlikely that one entity 

will have all the program responsibility. However, the total management 

program should have the combined authority to perform the necessary 

functions. 

In each jurisdiction, the authority of each management entity should be 

examined. Statutory authority, judicial decisions, and the state 

constitution must be carefully reviewed. Often existing programs may be 

adapted and/or utilized to aid in management. For example, the 

management entities may require that certain onsite systems be designed 

by registered professional engineers even though the entities themselves 

do not register engineers. In the event that additional authority is 

needed, enabling statutory language will be required. 

10.3 Types of Management Entities 

There are several types of entities that have the authority to perform 

the management functions previously described. These include: 

1. State agencies 

2. Local governmental/quasi-governmental units 

3. Special purpose districts 

4. Private institutions (profit, nonprofit) 

355

10.3.1 State Agencies 

Except for the limitations contained in its own constitution, each state 

retains complete authority to protect the general welfare of its citi- 

zens, including the management of onsite systems. The state health 

agency and/or agency responsible for water quality are the agencies most 

likely to exercise the state's authority. 

The degree of control exerted by state agencies over onsite systems 

varies from state to state. Many states set design standards for onsite 

systems. Those that do not set standards delegate authority to local 

governments to do so. Several states retain the responsibility for 

administrative/technical portions of the onsite management program. 

A state management program is often considered more effective, because 

local pressures to weaken onsite regulation are not thought to be as 

effective at the state level. In addition, since states typically have 

more resources to hire or retain experienced individuals than most local 

units of government, state agencies are in a better position to take 

responsibility for many of the regulatory and administrative require- 

ments. 

10.3.2 Local Governmental/Quasi-Governmental Units 

In some states, a portion or most of the responsibility of onsite system 

management is delegated by the legislature to units of local government. 

In other states with strong "home rule" powers, the local unit of gov- 

ernment has the authority to manage onsite systems even without being so 

delegated by the state legislature. The various types of local govern- 

mental units are: 

1. Municipalities - Incorporated units of government have full 

responsibility for the general welfare of its citizens; have 

broad financing authority, including the authority to levy 

property taxes, to incur general obligation debts, to use 

revenue bonding and to impose special assessments upon bene- 

fitted property; and are legal entities authorized to contract, 

commence law suits, and own property. 

2. Unincorporated Government (e.g., County) - Unincorporated gov- 

ernmental units often have authority equal to municipalities: 

however, these units may not have the authority for some onsite 

program management responsibilities, i.e., ownership of onsite 

systems which do not serve county institutions. Typically, 

356

these units have financial authority and legal entity status 

similar to municipalities. 

3. Quasi-Governmental Units - These units include regional (multi- 

county) water quality Soards, regional planning commissions, 

local or regional health departments/boards, councils of gov- 

ernment, and other agencies with the exception of special pur- 

pose entities. Their authority varies with the intended pur- 

pose of each unit; however, the financial authority is typi- 

cally less than that of municipalities and unincorporated gov- 

ernmental units. 

10.3.3 Special Purpose Districts 

Special purpose districts depend entirely on enabling legislation for 

their authority and extent of services. These districts are independent 

units of government, created to provide one or more services, such as 

water and wastewater services to those within their boundaries. If per- 

mitted by the enabling legislation, services may also be provided to 

others outside their boundaries. The boundaries are often permitted to 

cross local governmental boundaries so that services can be provided to 

all those in need, despite the fact that residents of the district 

reside on either side of local governmental boundaries (counties, towns, 

villages, etc.). 

Nearly all special purpose districts have sufficient financial authority 

to impose service charges, collect fees, impose special assessments upon 

property benefitted, and issue revenue and/or special assessment bonds. 

In addition, some special purpose districts receive the same financing 

authority enjoyed by municipalities, including the authority to levy 

taxes and incur general obligation debt (i.e., general obligation bonds 

backed by taxing authority). These districts are usually legal entities 

that may enter into contracts, sue, and be sued. 

10.3.4 Private Institutions 

Private institutions do not rely on enabling legislation, but are 

founded upon the right of individuals or corporations to enter into con- 

tracts. However, they are often subject to review or regulation by 

state public service or utility commissions. 

357

10.3.4.1 Private Nonprofit Institutions (Associations 

and Corporations) 

These entities include homeowners' associations, private cooperatives, 

and nonprofit corporations that provide services for onsite systems. 

The range of services may vary from merely providing maintenance to 

complete ownership of the system. The freedom of the contract permits 

this complete range of services; however, the association or corporation 

may be regulated by the state public service or public utility laws. 

10.3.4.2 Private-for-Profit Institutions 

This type of entity may be a sole proprietorship, partnership, or cor- 

poration that provides services for onsite systems. The homeowner or a 

group of owners (homeowners' associations) typically enters into a con- 

tract with this private entity for the provision of services. These 

services could include maintenance and operation of the owner's onsite 

system, or the private entity could own the systems and charge the 

homeowner for the use of the systems. The state public service or 

public utility commission may regulate the private entity. 

10.4 Management Program Functions 

A good management program consists of many functions that may be per- 

formed by one entity only or shared among several entities. The user of 

this manual is urged to review the range of functions discussed here, 

and to select entities that are best able to perform those functions. 

For a more complete discussion of the various functions, see References 

(2) and (3). 

10.4.1 Site Evaluation and System Design 

In developing a management program, a choice can be made between per- 

forming the site evaluation and system design functions within the 

entity itself or reviewing work done in the private sector. Table 10-l 

summarizes the suggested activities that should .be performed for both 

options. 

358

Scope of Activities 

Perform all site 

evaluations and 

provide system 

designs 

Review all site 

Gtions and 

system designs 

TABLE 10-l 

SITE EVALUATION AND SYSTEM DESIGN FUNCTIONS 

Administrative/Technical Regulatory/Enforcement 

Activities Activities 

a. Conduct site evaluations 

for each lot to be 

developed 

b. Identify and evaluate 

feasible (or permitted) 

system designs 

c. Design selected system 

a. Verify site evaluation 

procedures and data 

collected for each lot 

b. Review and approve or 

disapprove plans 

359 

a. 

b. 

C. 

a. 

b. 

Establish guidelines and 

procedures for 

identifying sites 

suitable for development 

Develop cost-effective- 

ness guidelines and 

evaluation procedures 

Establish design 

standards, construction 

specifications, and 

performance standards 


Issue construction permit 

Develop guidelines and 

procedures for 

identifying sites 

suitable for development 


Develop training, 

certification, or 

licensing program for 

site evaluators 

Establish design 

standards, construction 

specifications, and 

performance standards 

and/or 

Develop training 

certification or 


system designers 


Issue construction 

permit

10.4.1.1 Standards for Site Suitability, System 

Design, and Performance 

A state agency with appropriate authority may establish minimum stan- 

dards for site suitability, system design, and performance. This may be 

preferred over each management entity establishing its own standards. 

The advantages are (1) more unifomity of regulations throughout the 

state (although the local management entity may choose to be more strin- 

gent if it has the power to do so), and (2) more resources and experi- 

enced personnel at the state level to develop appropriate standards. 

10.4.1.2 Site Evaluation and System Design 

It may be desirable to include site evaluation and system design activi- 

ties as part of the management program. These activities could be per- 

formed by any of the entities making up the management program. How- 

ever, if the local management entity proposes to own and operate systems 

within its jurisdiction, this would be the preferred entity to perform 

these activities. Legal advice should be sought regarding liability 

which may result from undertaking this activity. 

As an alternative to performing site evaluations and system designs as 

part of the management program, these activities could be performed by 

site evaluators and system designers licensed or registered by the man- 

agement entity. Licensure or registration is suggested to assure quali- 

ty* However, such assurances can only be obtained if the license or 

registration is subject to suspension or revocation. Random or preap- 

proved site inspections by the management entity are suggested to check 

compliance with established procedures and standards, particularly where 

site limitations are anticipated. 

10.4.1.3 Plan Approval and Construction Permits 

The management process should be initiated either by submission of plans 

for review and approval or by application for a permit to construct a 

system. Either requirement for plan approval or permit issuance for 

construction of a system provides the management entity with a conveni- 

ent method of obtaining information about the site evaluation and system 

design. Site suitability and design standards may be easily enforced by 

refusing to approve plans or issue permits. 

Plan approval or permit programs at the state level may be more desira- 

ble than at the local level because of greater technical resources and 

isolation from local political pressures to allow development on poorly 

360

suited sites. As an alternative to the review of all applications, the 

state agency could review a random sample of the plans approved or per- 

mits issued by the local management entity. The state agency would have 

the authority to countermand local approval. However, it would be nec- 

essary to limit the period of time that the state agency has to act on 

the local action. 

10.4.2 Install ation 

As with site evaluation and system design, the management entities could 

choose to install all new systems themselves. This would be particu- 

larly desirable if ownership were to be retained by the entity. If not, 

the entity may choose to control installation through inspections. 

Table 10-2 summarizes the suggested activities that should be performed 

for both options. 

10.4.2.1 Construction Inspections 

A program to inspect the onsite system at each critical stage during 

construction is very desirable to prevent improper construction and pre- 

mature failure of the system. The inspection may be performed by any 

entity involved in the total management program, but it would be most 

appropriate for the entity that has responsibility for the rehabilita- 

tion or abandonment of improperly functioning systems. 

If the management entity does not perform the inspections, they could be 

performed by licensed or registered inspectors. A state agency would be 

the most likely entity to develop a program to train inspectors in pro- 

per design and construction techniques for all acceptable types of sys- 

tems. This would assure more uniform quality of inspections statewide. 

To further assure uniformity and thoroughness of inspections, checklists 

of specific items to be inspected for each type of permitted design 

could be developed. The inspectors would be required to certify that 

the checklist was completed after the inspector's personal inspection of 

the installation, and that all entries contained on the checklist are 

correct. To insure that inspections are timely, the management entity 

may require the system installer to give notice as to when the construc- 

tion of the system is to commence. 

361


Perform inspection/ 

supervision of 

construction 

Review construction 

Inspection/ 

supervision 

a. 

b. 

a. 

b. 

TABLE 10-2 

INSTALLATION FUNCTIONS 

Administrative/Technical 

Activities 

Perform construction 

inspection and/or 

supervision during 

various phases of 

construction 

Prepare as-built drawing 

Review certified 

inspection by licensed/ 

registered inspectors 

10.4.2.2 As-Built Drawings 

Require as-built drawing 

a. 

b. 

a. 

b. 

Regulatory/Enforcement 

Activities 

Develop guidelines and 

specifications for 

construction 

Record as-built drawing 

and issue system use 

permit 

Develop specifications 

for construction and 

checklists for inspection 


Develop training, 

certification or 


inspectors 

Record as-built drawing 

and issue system use 

permit 

It is not unusual for the system installed to be quite different from 

the drawings originally approved because of changes necessary during 

construction. As-built drawings become very valuable when inspection or 

servicing of the system is required. Therefore, a requirement for as- 

built drawings is a good practice. These plans could be indexed by 

street, address, name of original owner, installer, and legal descrip- 

tion. 

10.4.2.3 Training and Licensing of Installers 

To reduce the reliance on good construction supervision and inspections, 

a program to train and license or register installers could be estab- 

lished. Training would include presentation of design and construction 

techniques of all approved system types. To be effective, this program 

would have to be coupled with a strong enforcement program in which the 

license to install systems could be suspended or revoked. 

362


Traditionally, the responsibility for operation and maintenance of on- 

site systems has been left to the owner. This has been less than satis- 

factory. As an alternative; management entities are beginning to assume 

this responsibility. The program adopted may either be compulsory or 

voluntary. If voluntary, the management entities perform the mainte- 

nance or issue operating permits on receipt of an assurance that the 

proper maintenance was performed. Table 10-3 summarizes the suggested 

activities that should be performed for both options. 

10.4.3.1 Standards for Operation and Maintenance 

A standard for the operation and maintenance of each type of system 

used, stating the procedures to be used and the frequency with which 

they are to be performed, is desirable. These standards would include 

those necessary to regulate the hauling and disposal of residuals gener- 

ated by onsite systems as well. The state agency would be the preferred 

entity to set these standards. The advantages of having the state set 

the standards include more uniformity in the regulations and more re- 

sources and experienced personnel to develop appropriate standards. 

10.4.3.2 Operating Permits 

Rather than the management entities providing services, compliance with 

operation and maintenance standards could be assured through an opera- 

ting permit program. The type and frequency of maintenance required for 

each type of system would be established by the entity. An operating 

permit allowing the owner to use the system would be renewed only if the 

required maintenance is performed. The system owner would be notified 

when the permit is about to expire, and told what maintenance must be 

performed to obtain a renewal. The owner would be required to have the 

necessary maintenance performed by an individual licensed or registered 

to perform such services within a specified period of time (e.g., 60 

days). This individual would sign and date one portion of the owner's 

permit, thereby certifying that the service was performed. 

The enabling ordinance or statutory language establishing this permit 

program must indicate that it is unlawful to occupy a home served by an 

onsite system unless the owner holds a valid operating permit. Thus, if 

the permit were not renewed, the owner would be in violation of the ord- 

inance or statute. From a legal viewpoint, enforcement of this type of 

violation is straightforward. 

363


Perform necessary 

operation/ 

maintenance 

TABLE 10-3 

OPERATION AND MAINTENANCE FUNCTIONS 

Administrative/Technical 

Activities 

a. Provide routine and 

emergency operation/ 

maintenance of each 

system 

b. Determine if operation/ 

maintenance program is 

voluntary or compulsory 

Regulatory/Enforcement 

Activities 

a. Develop guidelines and 

schedules for routine 

operation/maintenance 

b. Establish operation/ 

maintenance program 

Administer a. Establish an operation a. Develop guidelines and 

operation/ and maintenance program schedules for routine 

maintenance program operation/maintenance 


Obtain legal authority 

for right of access to 

private property 


Impose standards for 

hauling and disposal of 

residuals 

b. Determine if operation/ b. Develop system for 

maintenance program is notifying owner of 

voluntary or compulsory required operation/ 

maintenance 

c. Develop policies for 

regulating operation/ 

maintenance activities 

364 


Issue a regularly renewed 

operating permit after 

certification that proper 

operation/maintenance 

has been performed 

c. Develop training, 

certification, or 


those contracting to 

perform operation/ 

maintenance activities

10.4.3.3 Licensure/Registration 

To provide assurance that onsite systems are properly operated and main- 

tained, licensing or registering of qualified individuals is desirable. 

This could be done at the state level. If licensure/registration pro- 

grams for individuals, such as plumbers, residual waste haulers, sani- 

tarians, etc., already exist, and if these individuals have sufficient 

knowledge of onsite systems, an additional program may not be necessary. 

10.4.4 Rehabilitation 

Because onsite systems are usually located on private property and below 

ground, system failures are difficult to detect. If a management pro- 

gram is to effectively prevent public health hazards, environmental 

degradation, and nuisances, identification and correction of failures 

are a necessary part of the management program. Table 10-4 summarizes 

the suggested activities that should be performed. 


TABLE 10-4 

REHABILITATION FUNCTIONS 

Detect and correct a. Develop procedures for 

improperly identifying improperly 

functioning systems functioning systems 

(Sanitary surveys, 

presale inspections, 

etc.1 

Administrative/Technical Regulatory/Enforcement 

Activities Activities 

b. Rehabilitate system 

365 

a. Develop performance 

standards 


Obtain legal authority 

for right of access to 

private property 

b. Issue order requiring 

rehabilitation 

or 

Rehabilitate system as 

part of operation/ 

maintenance program

10.4.4.1 Inspections 

Inspections could be performed as part of a sanitary survey of the area 

or through presale inspections during real estate transactions. The 

latter option may require enabling legislation. Constitutional re- 

straints regarding the inspection of private property and the limita- 

tions on the sale of property have to be considered prior to enacting 

such legislation. 

10.4.4.2 Orders and Violations 

The management entity needs the authority to issue orders requiring the 

repair, replacement, or abandonment of improperly functioning systems if 

the systems are not owned by the entity. Various state agencies have 

this authority. If the owner does not comply with the order to repair 

or rehabilitate the system, the management entity could require that 

copies of all violations be filed with the registrar of deeds or a 

similar official. The effect of such a filing requirement would be to 

give notice of the violation in the chain of title whenever an abstract 

or a title insurance policy is prepared. Any potential mortgagee or 

buyer would thereby be alerted to the violation. 


1. 

2. 

3. 

Plews, G. D. The Adequacy and Uniformity of Regulations for On-Site 

Wastewater Disposal - A State Viewpoint. In: National Conference 

on Less Costly Wastewater Treatment Systemsfor Small Communities. 

EPA 600/9-79-010, NTIS Report No. PB 293 254, April 1977. pp. 

20-28. 


Madison, Management of Small Waste Flows. EPA 600/2-78-173, NTIS 

Report No. PB 286 560, September 1978. 

Interim Study Report, Management of On-Site and Small Community 

Wastewater Systems. M687, U.S. Environmental Protection Agency, 

Municipal Environmental Research Laboratory, Cincinnati, Ohio, 1979. 

366

A.1 Introduction 

APPENDIX A 

SOIL PROPERTIES AND SOIL-WATER RELATIONSHIPS 

An understanding of how water moves into and through soil is necessary 

to predict the potential of soil for wastewater absorption and treat- 

ment. Water moves through the voids or pore spaces within soil. There- 

fore, the size, shape, and continuity of the pore spaces are very impor- 

tant. These characteristics are dependent on the physical properties of 

the soil and the characteristics of water as well. 

A.2 Physical Properties of Soil 

A.2.1 Soil Texture 

Texture is one of the most important physical properties of soil because 

of its close relationship to pore size, pore size distribution and pore 

continuity. It refers to the relative proportion of the various sizes 

of solid particles in the soil that are smaller than 2 mm in diameter. 

The particles are commonly divided into three size fractions called soil 

"separates." These separates are given in Figure A-l. The U.S. Depart- 

ment of Agriculture (USDA) system is used in this manual (Table A-l). 

TABLE A-l 

U.S. DEPARTMENT OF AGRICULTURE SIZE LIMITS FOR SOIL SEPARATES 

Soil Separate Size Range 

mm 

Tyler Standard 

Sieve No. 

Sand 2-0.05 lo-270 mesh 

Very coarse sand 2-l lo-16 mesh 

Coarse sand l-0.5 16-35 mesh 

Medium sand 0.5-0.25 35-60 mesh 

Fine sand 0.25-0.1 60-140 mesh 

Very fine sand 0.1-0.05 140-270 mesh 

Silt 0.25-0.002 em- 

Clay co.002 --- 

367

SYSTEM 

1. U.S. Bureau of 

Reclam$t~on and 

Corps of Engmeers (U.S 

Dew. of the Army) 

2. American Assoclatlon 

of State Htghway 

Offlcals 

3. American Socwty for 

Testing and Materials 

4. Wentworth 

5. U.S. Department of 

Agriculture 

6 International Society 

of So11 Science 

,I 

Used In so11 englneerlng 

I, Used in geology. 

-Clay e 

I 

ollolds 

I 

I 

-ClaY 

I 

olloids 

’ USDA system used In IIlls manual 

11 Used !n soal science. 

FIGURE A-l 

NAMES AND SIZE LIMITS OF PRACTICAL-SIZE 

CLASSES ACCORDING TO SIX SYSTEMS (1) 

I SIII 

I I 

SIII Fine sand t )oarse sand Fine gravel 

Slh 

I 

I ( 

Fme sand 

Medium Coarse 

sand sand 

I I 

I 

Med’um ‘Oar 

gravel 1 graw 

Gravel 

VerV Fine Medium 

ftne 

’ l~$“G,,l,~,es Pebbles 

s?nd sand sand c 

I 

oarse 

sand I 

Fine Medium 

sand sand Coarse 

sand 

Very 

coarse 

sand Fine gravel Coarse grave 

Clay Fine sand Coarse sand Gravel 

POI txle diameter. mm 

rl 

Cobbles 

Boulders 

- 

obbles 

I 

Cobbles

Twelve textural classes are defined by the relative proportions of the 

sand, silt ,and clay separates. These are represented on the textural 

triangle (Figure A-2). To determine the textural class of a soil hori- 

zon, the percent by weight of the soil separates is needed. For exam- 

ple, a sample containing 37% sand, 45% silt and 18% clay has a textural 

class of loam. This is illustrated in Figure A-Z. 

Soil textural classes are modified if particles greater than 2 mm in 

size are present. The adjectives "gravelly," "cobbly," and "stoney" are 

used for particles between 2 and 75 mm, 75 and 250 mm, or 250 mm, re- 

spectively, if more than 15% to 20% of the soil volume is occupied by 

these fragments. 

Soil permeability, aeration and drainage are closely related to the soil 

texture because of their influence on pore size and pore continuity. 

They are also related to the soil's ability to filter particles and 

retain or adsorb pollutants from the waste stream. For example, fine 

textured or clayey soils do not transmit water rapidly or drain well 

because the pores are very small. They tend to retain water for long 

periods of time. 

However, they act as better filters and can retain 

more chemicals than soils of other textures. On the other hand, coarse 

textured or sandy soils have large, continuous pores that can accept and 

transmit large quantities of water. They retain water for only short 

periods of time. The capacity to retain chemicals is generally low and 

they do not filter wastewater as well as finer textured soils. Medium 

textured or loamy soils have a balance between wastewater absorption and 

treatment capabilities. They accept and transmit water at moderate 

rates, act as good filters, and retain moderate amounts of chemical 

constituents. 

A.2.2 Soil Structure 

Soil structure has a significant influence on. the soil's acceptance and 

transmission of water. Soil structure refers to the aggregation of soil 

particles into clusters of particles, called peds, that are separated by 

surfaces of weakness. These surfaces of weakness open planar pores be- 

tween the peds that are often seen as cracks in the soil. These planar 

pores can greatly modify the influence of soil texture on water move- 

ment. Well structured soils with large voids between peds will transmit 

water more rapidly than structureless soils of the same texture, partic- 

ularly if the soil has become dry before the water is added. Fine tex- 

tured, massive soils (soils with little structure) have very slow per- 

colation rates. 

369

FIGURE A-2 

TEXTURAL TRIANGLE DEFINING TWELVE TEXTURAL CLASSES OF THE USDA 

(ILLUSTRATED FOR A SAMPLE CONTAINING 37% SAND, 45% SILT, AND 18% CLAY) 

100% 0 

clay 

90 - 10 

A 

0 

100% 90 80 70 60 50 40 30 20 10 0 

sand Percent Sand 

by Weight 

370 

00% 

silt

The form, size and stability of the aggregates or peds depend on the 

arrangement of the soil particles and the bonds between the particles. 

The four major types of structures include platy, blocky, prismatic and 

granular. Detailed descriptions of types and classes of soil structure 

used by SCS are given in Table A-2. 

Between the peds are voids which are often relatively large and continu- 

ous compared to the voids or pores between the primary particles within 

the peds. The type of structure determines the dominant direction of 

the pores and, hence, water movement in the soil. Platy structures re- 

strict vertical percolation of water because cleavage faces are horizon- 

tally oriented. Often, vertical flow is so restricted that the upper 

soil horizons saturate, creating a perched water table. Soils with 

prismatic and columnar structure enhance vertical water flow, while 

blocky and granular structures enhance flow both horizontally and 

vertically. 

The soil's permeability by air and water is also influenced by the fre- 

quency and degree of expression of the pores created by the structual 

units. These characteristics depend upon the size of the peds and their 

grade or durability. Small structural units create more pores in the 

soil than large structural units. Soils with strong structure have 

distinct pores between peds. Soils with very weak structure, or soils 

without peds or planes of weakness, are said to be structureless. 

Structureless sandy soils are called single grained or granular, while 

structureless clayey soils are called massive. 

Structure is one soil characteristic that is easily altered or de- 

stroyed. It is very dynamic, changing in response to moisture content, 

chemical composition of soil solution, biological activity, and manage- 

ment practices. Soils containing minerals that shrink and swell appre- 

ciably, such as montmorillonite clays, show particularly dramatic 

changes. When. the soil peds swell upon wetting, the large pores become 

smaller, and water movement through the soil is reduced. Swelling can 

also result if the soil contains a high proportion of sodium salts. 

Therefore, when determining the hydraulic properties of a soil for 

wastewater disposal, soil moisture contents and salt concentrations 

should be similar to that expected in the soil surrounding a soil dis- 

posal system. 

A.2.3 Soil Color 

The color and color patterns in soil are good indicators of the drainage 

characteristics of the soil. Soil properties, location in the land- 

scape, and climate all influence water movement in the soil. These fac- 

tors cause some soils to be saturated or seasonally saturated, affecting 

371

Class Platelike. with 

one dimension 

(the vertical) 

limited and 

greatly less 

than the other 

two; arranged 

around a hori- 

TABLE A-2 . 

TYPES AND CLASSES OF SOIL STRUCTURE 

TYPE (shape and arrangement of peds) 

Prismlike. with two dimensions Blocklike, polyhedronlike, or spheroids, or with three dimensions of 

(the horizontal) limited and con- the same order of magnitude, arranged around a point. 

siderably less than the vertical; 

arranged around a vertical line; Blocklike; blocks or polyhedrons Spheroids or polyhedrons having 

vertical faces well defined; having plane or curved surfaces plane or curved surfaces which 

vertices angular that are casts of the molds formed have slight or no accommodations 

by the faces of the surrounding to the faces of surrounding peds 

peds 

zontal plane 

faces mostly Without With rounded Faces flattened, Mixed rounded Nonporous Porous peds 

horizontal rounded caps caps most vertices and flattened peds 

sharply angular faces with many 

rounded vertices 

Platy Prismatic Columnar (Angular) (Subangular) 

Blocky’ Blockyf 

Granular Crumb 

Very fine or Very thin Very fine pris- Very fine Very fine angu- Very fine sub- Very fine Very fine 

very thin platy; Cl mm matic; columnar; lar blocky; angular blocky; angular; crumb; < 1 mm 

Cl0 mm (10 mm (5 mm lOO mm >50mm blocky; >10 mm 

b.50 mm 

372

their ability to absorb and treat wastewater. Interpretation of soil 

color aids in identifying these conditions. 

Soil colors are a result of the color of primary soil particles, coat- 

ings of iron and manganese oxides, and organic matter on the particles. 

Soils that are seldom or never saturated with water and are well aer- 

ated, are usually uniformly red, yellow or brown in color. Soils that 

are saturated for extended periods or all the time are often grey or 

blue in color. Color charts have been developed for identifying the 

various soil colors. 

Soils that are saturated or nearly saturated during portions of the year 

often have spots or streaks of different colors called mottles. Mottles 

are useful to determine zones of saturated soil that may occur only dur- 

ing wet periods. Mottles result from chemical and biochemical reactions 

when saturated conditions, organic matter, and temperatures above 4" C 

occur together in the soil. Under these conditions, the bacteria pres- 

ent rapidly deplete any oxygen present while feeding on the organic mat- 

ter. When the oxygen is depleted, other bacteria continue the organic 

decomposition using the oxidized iron and manganese compounds, rather 

than oxygen, in their metabolism. Thus, the insoluble oxidized iron and 

manganese, which contribute much of the color to soil, are reduced to 

soluble compounds. This causes the soil to lose its color, turning the 

soil grey. When the soil drains, the soluble iron and magnesium are 

carried by the water to the larger soil pores. Here they are reoxidized 

when they come in contact with the oxygen introduced by the air-filled 

pores, forming insoluble compounds once again. The result is the for- 

mation of red, yellow and black spots near surfaces, and the loss of 

color, or greying, at the sites where the iron and manganese compounds 

were removed. (Examples of mottled soils are shown in Figure 3-20). 

Therefore, mottles seen in unsaturated soils can be interpreted as an 

indication that the soil is periodically saturated. Periodic saturation 

of soil cannot always be identified by mottles, however. Some soils can 

become saturated without the formation of mottles, because one of the 

conditions needed for mottle formation is not present. Experience and 

knowledge of moisture regimes related to landscape position and other 

soil characteristics are necessary to make proper interpretations in 

these situations. 

Also, color spots and streaks can be present in soils for reasons other 

than soil saturation. For example, soil parent materials sometimes cre- 

ate a color pattern in the soil similar to mottling. However, these 

patterns usually can be distinguished from true mottling. Some very 

sandy soils have uniform grey colors because there are no surface coat- 

ings on the sand grains. This color can mistakenly be interpreted as a 

gley or a poor draining color. Direct measurement of zones of soil 

373

saturation may be necessary to confirm the soil moisture regimes if in- 

terpretations of soil colors are not possible. 

A.2.4 Soil Horizons 

A soil horizon is a layer of soil approximately parallel to the soil 

surface with uniform characteristics. Soil horizons are identified by 

observing changes in soil properties with depth. Soil texture, struc- 

ture, and color changes are some of the characteristics used to deter- 

mine soil horizons. 

Soil horizons are commonly given the letter designations of A, B, and C 

to represent the surface soil, subsoil, and substratum, respectively. 

Not all soils have all three horizons. On the other hand, many soils 

show variations within each master horizon and are subdivided as Al, A2, 

A3, and Bl, etc. Some example soils and their horizons are shown in 

Figure A-3. 

Each horizon has its own set of characteristics and therefore will re- 

spond differently to applied wastewater. Also, the conditions created 

at the boundary between soil horizons can significantly influence waste- 

water flow and treatment through the soil. Therefore, an evaluation of 

a soil must include a comparison of the physical properties of each 

horizon that influences absorption and treatment of wastewater. 

A.2.5 Other Selected Soil Characteristics 

Bulk density and clay mineralogy are other soil characteristics that can 

significantly influence water infiltration and percolation in soils. 

Soil bulk density is the ratio of the mass of soil to its bulk or volume 

occupied by the soil mass and pore space. There is not a direct corre- 

lation between bulk density and soil permeability, since sandy soils 

generally have a higher bulk density and permeability than clayey soils. 

However, of soils with the same texture, those soils with the higher 

bulk densities are more compact with less pore volume. Reduced porosity 

reduces the hydraulic conductivity of the soil. Fragipans are examples 

of horizons that have high bulk densities and reduced permeabilities. 

They are very compact horizons rich in silt and/or sand but relatively 

low in clay, which commonly interferes with water and root penetration. 

The mineralogy of clay present in the soil can have a very significant 

influence on water movement. Some clay minerals shrink and swell appre- 

ciably with changes in water content. Montmorillonite is the most com- 

mon of these swelling clay minerals. Even if present in small amounts, 

374

FIGURE A-3 

SCHEMATIC DIAGRAM OF A LANDSCAPE 

AND DIFFERENT SOILS POSSIBLE 

DnC2 

B - Subsoil 

C - Substratum 

-llgBBBBB 

! B - Subsoil 

C - Substratum I 

I-

the porosity of soils containing montmorillonite can vary dramatically 

with varying moisture content. When dry, the clay particles shrink, 

opening the cracks between peds. But when wet, the clay swells, closing 

the pores. 

A.3 Water in the Soil‘System 

A.3.1 Soil Moisture Potential 

Soil permeability, or the capability of soil to conduct water, is not 

determined by the soil porosity but, rather, the size, continuity, and 

tortuosity of the pores. A clayey soil is more porous than a sandy 

soil, yet the sandy soil will conduct much more water because it has 

larger, more continuous pores. Under natural drainage conditions, some 

pores in the soil are filled with water. The distribution of this water 

depends upon the characteristics of the pores, while its movement is de- 

termined by the relative energy status of the water. Water flows from 

points of higher energy to points of lower energy. The energy status is 

referred to as the moisture potential. 

The total soil moisture potential has several components, of which the 

gravitational and matric potential are the most important. The gravita- 

tional potential is the result of the attraction of water toward the 

center of the earth by a gravitational force and is equal to the weight 

of water. The potential energy of the water at any point is determined 

by the elevation of that point relative to some reference level. Thus, 

the higher the water above this reference, the greater its gravitational 

potential. 

The matric potential is produced by the affinity of water molecules to 

each other and to solid surfaces. Molecules within the body of water 

are attracted to other molecules by cohesive forces, while water mole- 

cules in contact with solid surfaces are more strongly attracted to the 

solid surfaces by adhesive forces. The result of these forces acting 

together draws water into the pores of the soil. The water tries to wet 

the solid surfaces of the pores due to adhesive forces and pulls other 

molecules with it due to cohesive forces. This phenomenon is referred 

to as capillary rise. The rise of water is halted when the weight of 

the water column 'is equal to the force of capillarity. Therefore, water 

rises higher and is held tighter in smaller pores than in larger pores 

(see Figure A-4). Upon draining, the largest pores empty first because 

they have the weakest hold on the water. Therefore, in unsaturated 

soils, the water is held in the finer pores because they are better able 

to retain the water against the forces of gravity. 

376

FIGURE A-4 

UPWA,RD MOVEMENT BY CAPILLARITY IN GLASS 

TUBES AS COMPARED WITH SOILS (2) 

Air Spaces /Soil Particle 

dsorbed Water 

The ability of the soil to draw or pull water into its pores is referred 

to as its matric potential. Since the water is held against the force 

of gravity, it has a pressure less than atmospheric. This negative 

pressure is often referred to as soil suction or soil moisture tension. 

Increasing suction or tension is associated with soil drying. 

The moisture content of soils with similar moisture tensions varies with 

the nature of the pores. Figure A-5 illustrates the change in moisture 

content versus changes in moisture tensions. When the soil is satu- 

rated, all the pores are filled with water and no capillary suction 

occurs. The soil moisture tension is zero. When drainage occurs, the 

tensions increase. Because the sand has many relatively large pores, it 

drains abruptly at relatively low tensions, whereas the clay releases 

only a small volume of water over a wide tension range because most of 

it is strongly retained in very fine pores. The silt loam has more 

coarse pores than does the clay, so its curve lies somewhat below that 

of the clay. The sandy loam has more finer pores than the sand so its 

curve lies above that of the sand. 

377

FIGURE A-5 

SOIL MOISTURE RETENTION FOR FOUR 

DIFFERENT SOIL TEXTURES (3) 

- 601 

A.3.2 Flow of Water in Soil 

0 I, 

20 40 60 80 100 

Soil Moisture Tension (MBAR) 

Soil Drying--------$) 

The flow of water in soil depends on the soil's ability to transmit the 

water and the presence of a force to drive it. Hydraulic conductivity 

is defined as the soil's ability to transmit water, and is related to 

the number, size, and configuration of the pores. Soils with large, 

continuous water-filled pores can transmit water easily and have a high 

conductivity. while soils with small, discontinuous water-filled pores 

offer a high resistance to flow, and, therefore, have low conductivity. 

When the soil is saturated, all .pores are water-filled and the conduc- 

tivity depends on all the soil pores. When the soil becomes unsaturated 

or dries (see Figure A-51, the larger pores fill with air, and only the 

smaller water-filled pores may transmit the water. Therefore, as seen 

in Figure A-6, the hydraulic conductivity decreases for all soils as 

they dry. Since clayey soils have more fine pores than sandy soils, the 

hydraulic conductivity of a clay is greater than a sand beyond a soil 

moisture tension of about 50 mbar. 

378

HYDRAULIC 

SOIL 

1000 

FIGURE A-6 

CONDUCTIVITY (K) VERSUS 

MOISTURE RETENTION (4) 

20 40 60 80 100 

Soil Moisture Tension (MB&I) 

Drying - 

Water movement in soil is governed by the total moisture potential gra- 

dient and the soil's hydraulic conductivity. The direction of movement 

is from a point of higher potential (gravity plus matric potential) to a 

point of lower potential. When the soil is saturated, the matric poten- 

tial is zero, so the water moves downward due to gravity. If the soil 

is unsaturated, both the gravity and matric potentials determine the 

direction of flow, which may be upward, sideward, or downward depending 

on the difference in total potentials surrounding the area. The greater 

the difference in potentials between two points, the more rapid the 

movement. However, the volume of water moved in a given time is propor- 

tional to the total potential gradient and the soils hydraulic conduc- 

tivity at the given moisture content. Therefore, soils with greater 

hydraulic conductivities transmit larger quantities of water at the same 

potential gradient than soils with lower hydraulic conductivities. 

379

A.3.3 Flow of Water Through Layered Soils 

Soil layers of varying hydraulic conductivities interfere with water 

movement. Abrupt changes in conductivity can cause the soil to saturate 

or nearly saturate above the boundary regardless of the hydraulic con- 

ductivity of the underlying, layer. If the upper layer has a signifi- 

cantly greater hydraulic conductivity, the water ponds because the lower 

layer cannot transmit the water as fast as the upper layer delivers it. 

If the upper layer has a lower conductivity, the underlying layer cannot 

absorb it because the finer pores in the upper layer hold the water 

until the matric potential is reduced to near saturation. 

Layers such as these may occur naturally in soils or as the result of 

continuous wastewater application. It is common to develop a clogging 

mat of lower hydraulic conductivity at the infiltrative surface of a 

soil disposal system. This layer forms as a result of suspended solids 

accumulation, biological activity, compaction by construction machinery, 

and soil slaking (3). The clogging mat may restrict water movement to 

the point where water is ponded above, and the soil below is unsatur- 

ated. Water passes through the clogging mat due to the hydrostatic 

pressure of the ponded water above pushing the water through, and the 

soil suction of the unsaturated soil below pulling it through. 

Figure A-7 illustrates three columns of similar textured soils with 

clogging mats in various stages of development. Water is ponded at 

equal heights above the infiltrative surface of each column. 

Column A has no clogging mat so the water is able to pass through all 

the pores, saturating the soil. The moisture tension in this column is 

zero. Column B has a permeable clogging mat developed with moderate 

size pores. Flow into the underlying soil is restricted by the clogging 

mat to a rate less than the soil is able to transmit it. Therefore, the 

large pores in the soil empty. With increasing intensity of the mat, as 

shown in Column C, the flow rate through the soil is reduced to very low 

levels. The water is forced to flow through the finest pores of the 

soil, which is a very tortuous path. Flow rates through identical clog- 

ging mats developed on different soils will vary with the soil's capil- 

lary characteristics. 

A.4 Evaluating Soil Properties 

To adequately predict how soil responds to wastewater application, the 

soil properties described and other site characteristics must be 

identified. The procedures used to evaluate soils are described in 

Chapter 3 of this manual. 

380

A.5 References 

FIGURE A-7 

SCHEMATIC REPRESENTATION OF WATER MOVEMENT THROUGH 

A SOIL WITH CRUSTS OF DIFFERENT RESISTANCES 

q $; Clogging Layer q Pore El Particle 

A B C 

1. Black, C. A. Soil Plant Relationships. 2nd ed. Wiley, New York, 

1968. 799 pp. 

2. Brady, N. C. The Nature and Properties of Soils. 8th ed. MacMil- 

lan, New York, 1974. 655 pp. 

3. Bouma, J. W., A. Ziebell, W. G. Walker, P. G. Olcott, E. McCoy, and 

F. D. Hole. Soil Absorption of Septic Tank Effluent. Information 

Circular 20, Wisconsin Geological and Natural History Survey, Madi- 

son, 1972. 235 pp. 

4. Bouma, J. Unsaturated Flow During Soil Treatment of Septic Tank 

Effluent. J. Environ. Eng., Am. Sot. Civil Eng., 101:967-983, 1975. 

381

GLOSSARY 

A horizon: The horizon formed at or near the surface, but within the 

mineral soil, having properties that reflect the influence of accu- 

mulating organic matter or eluviation, alone or in combination. 

absorption: The process by which one substance is taken into and in- 

cluded within another substance, as the absorption of water by soil 

or nutrients by plants. 

activated sludge process: A biological wastewater treatment process in 

which a mixture of wastewater and activated sludge is agitated and 

aerated. The activated sludge is subsequently separated from the 

treated wastewater (mixed liquor) by sedimentation and wasted or 

returned to the process as needed. 

adsorption: The increased concentration of molecules or ions at a sur- 

face, including exchangeable cations and anions on soil particles. 

aerobic: (1) Having molecular oxygen as a part of the environment. (2) 

Growing or occurring only in the presence of molecular oxygen, such 

as aerobic organisms. 

aggregate, soil: A group of soil particles cohering so as to behave me- 

chanically as a unit. 

anaerobic: (1) The absence of molecular oxygen. (2) Growing in the ab- 

sence of molecular oxygen (such as anaerobic bacteria). 

anaerobic contact process: An anaerobic waste treatment process in 

which the microorganisms responsible for waste stabilization are 

removed from the treated effluent stream by sedimentation or other 

means, and held in or returned to the process to enhance the rate 

of treatment. 

angstrom (ij): one hundred millionth of a centimeter. 

B horizon: The horizon immediately beneath the A horizon characterized 

by a higher colloid (clay or humus) content, or by a darker or 

brighter color than the soil immediately above or below, the color 

usually being associated with the colloidal materials. The 

colloids may be of alluvial origin, as clay or humus; they may have 

been formed in place (clays, including sesquioxides); or they may 

have been derived from a texturally layered parent material. 

382

iochemical oxygen demand (BOD): Measure of the concentration of organ- 

ic impurities in wastewater. The amount of oxygen required by bac- 

teria while stabilizing organic matter under aerobic conditions, 

expressed in mg/l, is determined entirely by the availability of 

material in the wastewater to be used as biological food, and by 

the amount of oxygen utilized by the microorganisms during 

oxidation. 

blackwater: Liquid and solid human body waste and the carriage waters 

generated ,through toilet usage. 

bulk density, soil: The mass of dry soil per unit bulk volume. The 

bulk volume is determined before drying to constant weight at 

105°C. 

C horizon: The horizon that normally lies beneath the B horizon but may 

lie beneath the A horizon, where the only significant change caused 

by soil development is an increase in organic matter, which 

produces an A horizon. In concept, the C horizon is unaltered or 

slightly altered parent material. 

calcareous soil: Soil containing sufficient calcium carbonate (often 

with magnesium carbonate) to effervesce visibly when treated with 

cold O.lN hydrochloric acid. 

capillary attraction: A liquid's movement over, or retention by, a 

solid surface, due to the interaction of adhesive and cohesive 

forces. 

cation exchange: The interchange between a cation in solution and 

another cation on the surface of any surface-active material, such 

as clay or organic colloids. 

cation-exchange capacity: The sum total of exchangeable cations that a 

soil can adsorb; sometimes called total-exchange, base-exchange ca- 

pacity, or cation-adsorption capacity. Expressed in milliequiva- 

lents per 100 grams or per gram of soil (or of other exchanges, 

such as clay). 

chemical oxygen demand (COD): A measure of the oxygen equivalent of 

that portion of organic matter that is susceptible to oxidation by 

a strong chemical oxidizing agent. 

chlorine residual: The total amount of chlorine (combined and free 

available chlorine) remaining in water, sewage, or industrial 

wastes at the end of a specified contact period following 

chlorination. 

clarifiers: Settling tanks. The purpose of a clarifier is to remove 

settleable solids by gravity, or colloidal solids by coagulation 

383

following chemical flocculation; will also remove'floating oil and 

scum through skimming. 

clay: (1) A soil separate consisting of particles X0.002 mm in equiva- 

lent diameter. (2) A textural class. 

clay mineral: Naturally occurring inorganic crystalline or amorphous 

material found in soils and other earthy deposits, the particles 

being predominantly

crust: A surface layer on soils, ranging in thickness from a few milli- 

meters to perhaps as much as an inch, that is much more compact, 

hard, and brittle when dry, than the material immediately beneath 

it. 

denitrification: The biochemical reduction of nitrate or nitrite to 

gaseous molecular nitrogen or an oxide of nitrogen. 

digestion: The biological decomposition of organic matter in sludge, 

resulting in partial gasifiction, liquefaction, and mineralization. 

disinfection: Killing pathogenic microbes on or in a material without 

necessarily sterilizing it. 

disperse: To break up compound particles, such as aggregates, into the 

individual component particles. 

dissolved oxygen (DO): The oxygen dissolved in water, wastewater, or 

other liquid, usually expressed in milligrams per liter (mg/l), 

parts per million (ppm), or percent of saturation. 

dissolved solids: Theoretically, the anhydrous residues of the dis- 

solved constituents in water. Actually, the term is defined by the 

method used in determination. 

effluent: Sewage, water, or other liquid, partially or completely 

treated or in its natural state, flowing out of a reservoir, basin, 

or treatment plant. 

effective size: The size of grain such that 10% of the particles by 

weight are smaller and 90% greater. 

eutrophic: A term applied to water that has a concentration of nutri- 

ents optimal, or nearly so, for plant or animal growth. 

evapotranspiration: The combined loss of water from a given area, and 

during a specified period of time, by evaporation from the soil 

surface and by transpiration from plants. 

extended aeration: A modification of the activated sludge process which 

provides for aerobic sludge digestion within the aeration system. 

filtrate: The liquid which has passed through a filter. 

fine texture: The texture exhibited by soils having clay as a part of 

their textural class name. 

floodplain: Flat or nearly flat land on the floor of a river valley 

that is covered by water during floods. 

385

floodway: A channel built to carry excess water from a stream. 

food to microorganism ratio (F/M): Amount of BOD applied to the acti- 

vated sludge system per day per amount of MLSS in the aeration 

basin, expressed as lb BOD/d/lb MLSS. 

graywater: Wastewater generated by water-using fixtures and appliances, 

excluding the toilet and possibly the garbage disposal. 

hardpan: A hardened soil layer, in the lower A or in the B horizon, 

caused by cementation of soil particles with organic matter or with 

materials such as silica, sesquioxides, or calcium carbonate. The 

hardness does not change appreciably with changes in moisture con- 

tent, and pieces of the hard layer do not slake in water. 

heavy soil: (Obsolete in scientific use.) A soil with a high content 

of the fine separates, particularly clay, or one with a high 

drawbar pull and hence difficult to cultivate. 

hydraulic conductivity: See conductivity, hydraulic. 

impervious: Resistant to penetration by fluids or by roots. 

influent: Water, wastewater, or other liquid flowing into a reservoir, 

basin, or treatment plant. 

intermittent filter: A natural or artificial bed of sand or other fine- 

grained material to the surface of which wastewater is applied in- 

termittently in flooding doses and through which it passes; oppor- 

tunity is given for filtration and the maintenance of an aerobic 

condition. 

ion: A charged atom, molecule, or radical, the migration of which af- 

fects the transport of electricity through an electrolyte or, to a 

certain extent, through a gas. An atom or molecule that has lost 

or gained one or more electrons; by such ionization it becomes 

electrically charged. An example is the alpha particle. 

ion exchange: A chemical process involving reversible interchange of 

ions between a liquid and a solid but no radical change in 

structure of the solid. 

leaching: The removal of materials in solution from the soil. 

lysimeter: A device for measuring percolation and leaching losses from 

a column of soil under controlled conditions. 

manifold: A pipe fitting with numerous branches to convey fluids be- 

tween a large pipe and several smaller pipes, or to permit choice 

of diverting flow from one of several sources or to one of several 

discharge points. 

386

mapping unit: A soil or combination of soils delineated on a map and, 

where possible, named to show the taxonomic unit or units included. 

Principally, mapping units on maps of soils depict soil types, 

phases, associations, or complexes. 

medium texture: The texture exhibited by very fine sandy loams, loams, 

silt loams, and silts. 

mineral soil: A soil consisting predominantly of, and having its pro- 

perties determined by, mineral matter. Usually contains (20 

percent organic matter, but may contain an organic surface layer up 

to 30 cm thick. 

mineralization: The conversion of an element from an organic form to an 

inorganic state as a result of microbial decomposition. 

mineralogy, soil: In practical use, the kinds and proportions of miner- 

als present in soil. 

mixed liquor suspended solids (MLSS): Suspended solids in a mixture of 

activated sludge and organic matter undergoing activated sludge 

treatment in the aeration tank. 

montmorillonite: An aluminosilicate clay mineral with a 2:l expanding 

structure; that is, with two silicon tetrahedral layers enclosing 

an aluminum octahedral layer. Considerable expansion may be caused 

by water moving between silica layers of contiguous units. 

mottling: Spots or blotches of different color or shades of color in- 

terspersed with the dominant color. 

nitrification: The biochemical oxidation of ammonium to nitrate. 

organic nitrogen: Nitrogen combined in organic molecules such as pro- 

teins, amino acids. 

organic soil: A soil which contains a high percentage (>15 percent or 

20 percent) of organic matter throughout the solum. 

particle size: The effective diameter of a particle usually measured by 

sedimentation or sieving. 

particle-size distribution: The amounts of the various soil separates 

in a soil sample, usually expressed as weight percentage. 

pathogenic: Causing disease. "Pathogenic" is also used to designate 

microbes which commonly cause infectious diseases, as opposed to 

those which do so uncommonly or never. 

387

ped: A unit of soil structure such as an aggregate, crumb, prism, 

block, or granule, formed by natural processes (in contrast with a 

clod, which is formed artificially). 

pedon: The smallest volume (soil body) which displays the normal range 

of variation in properties of a soil. Where properties such as 

horizon thickness vary little along a lateral dimension, the pedon 

may occupy an area of a square yard or less. Where such a property 

varies substantially along a lateral dimension, a large pedon sev- 

eral square yards in area may be required to show the full range in 

variation. 

percolation: The flow or trickling of a liquid downward through a con- 

tact or filtering medium. The liquid may or may not fill the pores 

of the medium. 

permeability, soil: The ease with which gases, liquids, or plant roots 

penetrate or pass through soil. 

pH: A term used to describe the hydrogen-ion activity of a system. 

plastic soil: A soil capable of being molded or deformed continuously 

and permanently, by relatively moderate pressure, into various 

shapes. See consistence. 

platy structure: Soil aggregates that are developed predominantly along 

the horizontal axes; laminated; flaky. 

settleable solids: That matter in wastewater which will not stay in 

suspension during a preselected settling period, such as one hour, 

but either settles to the bottom or floats to the top. 

silt: (1) A soil separate consisting of particles between 0.05 and 

0.002 mm in diameter. (2) A soil textural class. 

single-grained: A nonstructural state normally observed in soils con- 

taining a preponderance of large particles, such as sand. Because 

of a lack of cohesion, the sand grains tend not to assemble in ag- 

gregate form. 

siphon: A closed conduit a portion of which lies above the hydraulic 

grade line, resulting in a pressure less than atmospheric and re- 

quiring a vacuum within the conduit to start flow. A siphon uti- 

lizes atmospheric pressure to effect or increase the flow of water 

through the conduit. 

slope: Deviation of a plane surface from the horizontal. 

soil horizon: A layer of soil or soil material approximately parallel 

to the land surface and differing from adjacent genetically related 

388

layers in'physical, chemical, and biological properties or charac- 

teristics such as color, structure, texture, consistence, pH, etc. 

soil map: A map showing the distribution of soil types or other soil 

mapping units in relation to the prominent physical and cultural 

features of the earth's surface. 

soil morphology: The physical constitution, particularly the structural 

properties, of a soil profile as exhibited by the kinds, thickness, 

and arrangement of the horizons in the profile, and by the texture, 

structure, consistence, and porosity of each horizon. 

soil separates: Groups of mineral particles separated on the basis of a 

range in size. The principal separates are sand, silt, and clay. 

soil series: The basic unit of soil classification, and consisting of 

soils which are essentially alike in all major profile characteris- 

tics, although the texture of the A horizon may vary somewhat. See 

soil type. 

soil solution: The aqueous liquid phase of the soil and its solutes 

consisting of ions dissociated from the surfaces of the soil par- 

ticles and of other soluble materials. 

soil structure: The combination or arrangement of individual soil par- 

ticles into definable aggregates, or peds, which are characterized 

and classified on the basis of size, shape, and degree of distinct- 

ness. 

soil suction: A measure of the force of water retention in unsaturated 

soil. Soil suction is equal to a force per unit area that must be 

exceeded by an externally applied suction to initiate water flow 

from the soil. Soil suction is expressed in standard pressure 

terms. 

soil survey: The systematic examination, description, classification, 

and mapping of soils in an area. 

soil texture: The relative proportions of the various soil separates in 

a soil. 

soil type: In mapping soils, a subdivision of a soil series based on 

differences in the texture of the A horizon. 

soil water: A general term emphasizing the physical rather than the 

chemical properties and behavior of the soil solution. 

389

solids: Material in the solid state. 

total: The solids in water, sewage, or other liquids; includes 

suspended and dissolved solids; all material remaining as residue 

after water has been evaporated. 

dissolved: Solids present in solution. 

suspended: Solids physically suspended in water, sewage, or other 

liquids. The quantity of material deposited when a quantity of 

water, sewage, or liquid is filtered through an asbestos mat in a 

Gooch crucible. 

volatile: The quantity of solids in water, sewage, or other liquid 

lost on ignition of total solids. 

solids retention time (SRT): The average residence time of suspended 

solids in a biological waste treatment system, equal to the total 

weight of suspended solids in the system divided by the total 

weight of suspended solids leaving the system per unit time 

(usually per day). 

subsoil: In general concept, that part of the soil below the depth of 

plowing. 

tensiometer: A device for measuring the negative hydraulic pressure (or 

tension) of water in soil in situ; a porous, permeable ceramic cup 

connected through a tube to a manometer or vacuum gauge. 

tension, soil water: The expression, in positive terms, of the negative 

hydraulic pressure of soil water. 

textural class, soil: Soils grouped on the basis of a specified range 

in texture. In the United States, 12 textural classes are recog- 

nized. 

texture: See soil texture. 

tight soil: A compact, relatively impervious and tenacious soil (or 

subsoil), which may or may not be plastic. 

Total Kjeldahl Nitrogen (TKN): An analytical method for determining 

total organic nitrogen and ammonia. 

topsoil: (1) The layer of soil moved in cultivation. (2) The A hori- 

zon. (3) The Al horizon. (4) Presumably fertile soil material 

used to topdress roadbanks, gardens, and lawns. 

uniformity coefficient (UC): The ratio of that size of grain that has 

60% by weight finer than itself, to the size which has 10% finer 

than itself. 

390

unsaturated flow: The movement of water in a soil which is not filled 

to capacity with water. 

vapor pressure: (1) The pressure exerted by a vapor in a confined 

space. It is a function of the temperature. (2) The partial pres- 

sure of water vapor in the atmosphere. (3) Partial pressure of any 

liquid. 

water table: That level in saturated soil where the hydraulic pressure 

is zero. 

water table, perched: The water table of a discontinuous saturated zone 

in a soil. 

39.1

TECHNICAL REPORT DATA 

(Please read Insttuctions on the reverse bejore complefing) 

REPORT NO. 2. 3. RECIPIENT’S ACCESSION NO. 

EPA-625/l-80-012 

TITLE AND SUBTITLE 5. REPORT DATE 

DESIGN MANUAL: ONSITE WASTEWATER TREATMENT OCTOBER 1980 

AND DISPOSAL SYSTEMS 6. PERFORMING ORGANIZATION CODE 

AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO. 

Otis, Richard J., Boyle, William C., 

Clements, Ernest V,, and Schmidt, Curtis J. 

PERFORMING ORGANIZATION NAME AND ADORE% 10. PROGRAM ELEMENT NO. 

SCS Engineers Rural Systems Engineering 2BG647 

4014 Long Beach Blvd. P. 0. Box 9443 11. CONTRACT/GRANT NO. 

Long Beach, CA 90807 Madison, WI 53715 68-01-4904 

2. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AN0 PER100 COVERED 

U.S. Environmental Protection Agency - Final 

Water 4 Waste Management 

OWPO 

Washington, DC 20460 

Research E Development 

MERL 

Cincinnati, OH 45268 

EPA/700/02 

EPA/600/14 

5. SUPPLEMENTARY NOTES 

Project Officers: Robert M. Southworth (202)-426-2707 

Robert P. G, Bowker (513)-684-7620 

6. ABSTRACT 

14. SPONSORING AGENCY CODE 

Approximately 18 million housing units, or 25% of all housing units in the 

United States, dispose of their wastewater using onsite wastewater treatment 

and disposal systems. These systems include a variety of components and 

configurations, the most common being the septic tank/soil absorption system. 

The number of onsite systems is increasing, with about one-half million new 

systems being installed each year. 

This document provides information on generic types of onsite wastewater 

treatment and disposal systems. It contains neither standards for those 

systems nor rules and regulations pertaining to onsite systems. The design 

information presented is intended as technical guidance reflective of sound, 

professional practice. The intended audience for the manual includes those 

involved in the design, construction, operation, maintenance, and regulation 

of onsite systems. 

7. KEY WORDS AND DOCUMENT ANALYSIS 

Release to Public 

EPA Form 2220-l (Rev. 4-77) PRE”IO”S EDITION IS OBSOLETE 392

EXAMPLES OF SOIL MOTTLING (EXAMPLES A, B & C INDICATE 

SEASONAL SOIL SATURATION, EXAMPLE D DOES NOT) 

(A) 

Extremely Prominent Mottling 

in a Clayey Soil 

(Cl 

Mottling in a Sandy Soil 

(B) 

Mottling in a Loamy Soil 

(D) 

Mottling Inherited 

from Geologic Processes

On-Site Wastewater Treatment and Disposal Systems - Forced ...

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