EPA -660/2-73-006a
    August 1973
                        Environmental Protection Technology Series
   Wastewater Treatment And Reuse By

   Land Application - Volume I  - Summary

                                  Office of Research and Development

                                  U.S. Environmental Protection Agency
                                  Washington, O.C. 20460

Research  reports of the  Office  of  Research  and
Monitoring,   Environmental Protection  Agency, have
been grouped into five series.  These   five  broad
categories   were established to facilitate further
development   and  application   of   environmental
technology.    Elimination  of traditional grouping
was  consciously  planned  to  foster    technology
transfer   and  a  maximum  interface   in  related
fields.   The five series are:

   1.  Environmental Health Effects  Research
   2.  Environmental Protection Technology
   3.  Ecological Research
   4.  Environmental Monitoring
   5.  Socioeconomic Environmental Studies

This report  has  been assigned to the ENVIRONMENTAL
PROTECTION    TECHNOLOGY   series.    This   series
describes   research   performed  to  develop  and
demonstrate    instrumentation,    equipment    and
methodology   to   repair  or  prevent environmental
degradation  from point and  non-point   sources  of
pollution.   This work provides the new or improved
technology   required for the control and treatment
of pollution sources to meet environmental quality
                  EPA REVIEW NOTICE

This report has been reviewed by the Office of Research and
Development, EPA, and approved for publication. Approval does
not signify that the contents necessarily reflect the views
and policies of the Environmental Protection Agency, nor does
mention of trade names or commercial products constitute
endorsement or recommendation for use.

                                                       August 1973

                      BY LAND APPLICATION

                      VOLUME I -  SUMMARY

                       Charles E.  Pound
                       Ronald W.  Crites
                    Contract No.  68-01-0741
                    Program Element 1B2045
                        Project  Officer

                       Richard E.  Thomas
      Robert  S.  Kerr Environmental Research Laboratory
                        P. 0. Box  1198
                      Ada, Oklahoma 74820
                         Prepared for

                    WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.10

A nationwide study was conducted of the current knowledge
and techniques of land application of municipal treatment
plant effluents and industrial wastewaters.  Selected sites
were visited and extensive literature reviews were made
(annotated bibliography will be published separately).

Information and data were gathered on the many factors in-
volved in system design and operation for the three major
land application approaches:  irrigation, overland flow, and
infiltration-percolation.  In addition, evaluations were made
of environmental effects, public health consideration, and
costs--areas in which limited data are available.

Irrigation is the most reliable land application technique
with respect to long term use and removal of pollutants
from the wastewater.  It is sufficiently developed so
that general design and operational guidelines can be
prepared from current technology.

Overland flow was found to be an effective technique for in-
dustrial wastewater treatment.  Further development is
required to utilize its considerable potential for municipal
wastewater treatment.

Infiltration-percolation is also a feasible method of land
application.  Criteria for site selection, groundwater con-
trol, and management techniques for high rate systems need
further development.

This report is submitted in fulfillment of Contract 68-01-0741
by Metcalf § Eddy, Inc., Western Regional Office, under the
sponsorship of the Environmental Protection Agency.  Work
was completed as of April 1973.

Municipal and industrial wastewaters have been applied to
the land by many modes and for many purposes throughout the
country.  Crop irrigation with municipal effluent is prac-
ticed nationwide but most frequently in the western states.
Land application of industrial wastewater was pioneered in
states such as Iowa, Minnesota, Wisconsin, and Ohio.  Many
infiltration-percolation systems exist from California to
New York and Massachusetts.  Land application has been and
continues to be a feasible alternative to surface water
discharge in many cases.

Land application of wastewaters was given a substantial role
in the Federal Water Pollution Control Amendments of 1972 to
implement the "national goal that discharge of pollutants
into navigable waters be eliminated by 1985."  At several
points in the law the encouragement of land application is
emphasized.  Thus, land application techniques must be con-
sidered as alternatives to conventional and advanced waste-
water treatment in the prevention of surface water pollution,

Many times land application is interpreted in a narrow sense
to mean "spray irrigation" or "percolation ponds."  Land
application actually covers any technique involving inter-
action between soil and wastewater in which use is made of
the assimilative capacity of the soil system.  In this re-
port, land application techniques have been grouped into
the categories of irrigation, overland flow, and


Irrigation is the application of water to the land to meet
the growth needs of plants either by surface or spray appli-
cation, and is the predominant land application technique.
The use of wastewater for irrigation is attractive for
several reasons, including the following:  (1) it is a posi-
tive alternative to advanced wastewater treatment and sur-
face water discharge; (2) it can result in economic return

on the sale of crops; (3) it can be part of a water conser-
vation and reuse program; (4) it can provide fire protection
by forested hillside spraying; and (5) it can foster the
preservation and enlargement of greenbelts and open space.
This last factor is emphasized in the 1972 Federal Amend-
ments by the statement that "waste treatment management
which combines open space and recreational considerations
with such management" shall be encouraged.

The principal limitations to the practice of irrigation are
the considerable land area required, its relatively high
cost, and its relatively long distance away from large
urban sources of wastewater.  In some cases certain waste-
water characteristics, such as high salt or boron concen-
trations, may preclude irrigation of many crops, especially
in the arid Southwest.

Limitations to irrigation for health reasons are less
severe.  Adequately disinfected wastewater should not pose
a danger to health when it is used for irrigation.  Adequate
disinfection requires complete and rapid mixing and a speci-
fied contact time of the disinfectant in the effluent.  Any
aerosolizing of inadequately disinfected municipal waste-
water- -be it in an activated sludge plant, a river outfall,
or in a spray field--produces some risk to human health,
and all of these risks should be minimized.  Spraying down-
ward or horizontally (especially with low nozzle pressure),
adequate disinfection of the sprayed wastewater, and buffer
zones all function to increase the safeguards.


Overland flow or spray-runoff is a treatment method in which
wastewater is sprayed onto grassed slopes and allowed to
run off through the vegetated litter.  Overland flow is sub-
ject to the same types of limitations as irrigation, but it
can be done on relatively impermeable soil and a gently
sloping terrain.  The technique has considerable potential
for treatment of municipal wastewater.  At Ada, Oklahoma,
comminuted municipal wastewater has been sprayed at low
pressures in an experimental overland flow system.  The
effluent is of a quality approaching that from tertiary
treatment.  In addition to a relatively low construction
cost, the system produces no sludge, which is an aspect with
great appeal.

Operating costs are considerably lower than for conventional
plus advanced waste treatment because of the relative sim-
plicity of operation.  Further research and development of
this highly promising approach is required in the area of
phosphorus removal, loading rates, and applicability to cold

Overland flow has the advantages of avoiding groundwater
degradation, providing economic return through the growth
and sale of hay, and providing a high quality effluent suit-
able for industrial or agricultural reuse applications.
Although it cannot be used as a complete direct recycle of
wastewater to the land, the runoff will be of high quality
and can be directly recycled by any other land application


Infiltration-percolation is an approach to land application
in which large volumes of wastewater are applied to the
land, infiltrate the soil surface, and percolate through the
soil pores.  Benefits from infiltration-percolation of
municipal wastewater include the following:  (1) it is an
economic alternative to surface water discharge; (2) it is
a treatment system with nearly complete recovery of reno-
vated water; and (3) it is a method of repelling salt water
intrusion into aquifers.  The high rate systems pioneered
in the Southwest have the further benefit of requiring very
little land area.

The major limitations of the process are in connection with
groundwater effects.  The primary concern is that influent
nitrogen is converted to the nitrate form, which is leached
to the groundwater.  If the groundwater zone becomes anaero-
bic or anoxic, conversion of sulfates to hydrogen sulfide
may also be a problem.

Less critical limitations are that:  (1) phosphorus reten-
tion in the soil matrix may be neither complete nor of long
duration;  (2) suitable soils must be highly permeable yet
must contain enough fine particles to ensure adequate reno-
vation; and (3) to prevent groundwater degradation, the
aquifer receiving the water must be monitored and controlled
for high rate systems.


The potential use of land application for industrial waste-
waters is nearly as great as that for municipal wastewater.
In addition to the food processing, pulp and paper, and
dairy industries which have used land application exten-
sively, such diverse industries as tanneries and chemical
plants have also used land application successfully.  In
general, for plants located in rural or semirural areas
that produce wastewaters containing mainly organic compo-
nents, land application offers great potential.  For indus-
tries producing toxic or high inorganic content wastewaters,
land application probably offe.s small promise.  There are

so many modifications and combinations of land application
methods for any given industrial wastewater that no sweeping
limitations can be stated solely on the basis of a type of

In general, industries are more amenable than municipalities
to including new technology in their plans for wastewater
management, which partially explains their use of the over-
land flow approach.  Industries have allowed the soil matrix
to provide a greater amount of treatment than have munici-
palities and have tended to search out the limits of loading
for soil systems.  It is therefore likely that new improve-
ments or modifications to the common methods will continue
to come from industries as well as from soil scientists and

Because land application of wastewaters has attracted con-
siderable attention and controversy within professional,
academic, and governmental circles, the purpose of this re-
port is to focus on the principles involved in its use and
to place both the positive aspects or benefits and the
limitations in perspective.

ABSTRACT                                            ii

PERSPECTIVE                                         ii;

LIST OF FIGURES                                     ix

LIST OF TABLES                                      x

ACKNOWLEDGMENTS                                     xi:


I      CONCLUSIONS                                  1
       General                                      1
       Irrigation                                   2
       Overland Flow                                2
       Infiltration-Percolation                     2

II     RECOMMENDATIONS                              4
       Implementation of Land Application
         Projects                                   4
       Development of Standard Practices            4
       Research Needs                               5

III    INTRODUCTION                                 8
       Purpose and Scope of Report                  8
       Information Sources and Definition
         of Terms                                   9
       Historical Background                        10

IV     LAND APPLICATION APPROACHES                  12
       Irrigation                                   12
       Overland Flow                                18
       Infiltration-Percolation                     19
       Other Land Application Approaches            21
       Reliability of Application Approaches        21
       Approach Selection                           23

                   CONTENTS (Continued)


       Wastewater Characteristics                   26
       Site Characteristics                         30

VI     SYSTEM DESIGN AND OPERATION                  35
       Irrigation                                   35
       Overland Flow                                37
       Infiltration-Percolation                     39

VII    ENVIRONMENTAL EFFECTS                        42
       Climate                                      42
       Soil                                         43
       Vegetation                                   43
       Groundwater                                  44
       Surface Water                                45
       Air                                          46

       Regulations by State Agencies                47
       Survival of Pathogens                        47
       Groundwater Pollution                        49
       Insect Propagation                           49

IX     COST EVALUATION                              50
       Reported Costs                               50
       Cost Comparison for Hypothetical
         1-mgd Systems                              55

X      REFERENCES                                   59

XI     PUBLICATIONS                                 65

         AND CONVERSION FACTORS                     66
       Terms                                        66
       Abbreviations                                69
       Conversion Factors                           71

XIII   APPENDIX                                     72


No.                                                 Page

1      Land Application Approaches                  13

2      Soil Type Versus Liquid Loading Rates
       for Different Land Application Approaches    25

3      Generalized Climatic Zones for Land
       Application                                  32


No.                                                    Page

1      Historical Data on Sewage Farming              11

2      Comparative Characteristics «?f Irrigation,
       Overland Flow, and Infiltration-Percolation
       Systems                                        14

3      Site Selection Factors and Criteria for
       Effluent Irrigation                            15

4      Comparison of Irrigation, Overland Flow,
       and Infiltration-Percolation for Municipal
       Wastewater                                     24

5      Municipal Wastewater Characteristics           27

6      Characteristics of Various Industrial
       Wastewaters Applied to the Land                28

7      Reported Capital and Operating Costs for
       Spray Irrigation                               51

8      Reported Capital and Operating Costs for
       Ridge and Furrow Irrigation                    53

9      Reported Capital and Operating Costs for
       Flood Irrigation                               53

10     Comparison of Capital and Operating Costs
       for 1-mgd Spray Irrigation, Overland Flow,
       and Infiltration-Percolation Systems           56

11     Land Application Sites Visited for This
       Study                                          72

12     Sites Visited Prior to Study                   72

                    TABLES (Continued)

No.                                                   Page

13     Land Application Facilities,  On-Site
       Visits by APWA                                 73

14     Facilities Visited by APWA, Data Not
       Tabulated                                      76

15     Responses to Mail Survey by APWA               77

A great deal of cooperation has been received during the
conduct of this study.  Metcalf § Eddy, Inc., gratefully
acknowledges the cooperation of the personnel of all of the
cities and companies interviewed.

The leadership and assistance of Dr. Curtis C. Harlin, Chief,
Water Quality Control Program, Robert S. Kerr, Environmental
Research Laboratory, and Richard E. Thomas, Project Officer,
Environmental Protection Agency, is gratefully acknowledged.

Project assistance and report reviews were provided by
Consultants Donald M. Parmelee and Dr. George Tchobanoglous.
Material on climatic constraints was prepared by Consultant
Dr. J. R. Mather.

The American Public Works Association Research Foundation
made available information gathered by an extensive nation-
wide survey of land application facilities.  Metcalf § Eddy,
Inc., is indebted to Richard H. Sullivan of APWA and
Belford L. Seabrook, EPA Project Officer.

This project was conducted under the supervision and direc-
tion of Franklin L. Burton, Chief Engineer, and Charles E.
Pound, Project Manager.  The report, comprising Volumes I
and II, was written by Ronald W. Crites, Project Engineer,
Robert G. Smith, and David C. Tedrow.  Ferdinand K. Chen
assisted in the literature search.

                         SECTION I

Conclusions derived from this study of the present state-
of-the-art of land application of wastewater are presented
in four categories:  (1) general, (2) irrigation, (3)  over-
land flow, and (4) infiltration-percolation.


•    Irrigation, overland flow, and infiltration-percolation
     are the three general approaches used for the land
     application of municipal and industrial wastewater.

•    In actual practice, numerous modifications and combina-
     tions of land application techniques have proven

•    Factors to be considered in site selection for a land
     application system include both those involving eco-
     nomic and land use planning and such technical factors
     as soil type and drainability, topography, groundwater
     levels and quality, underlying geologic formations,
     wastewater characteristics, and pretreatment.

•    Primary, secondary, and intermediate quality municipal
     effluents have all been applied successfully to the
     land.  Industrial wastewaters from food processing,
     pulp and paper, dairy, tannery, and chemical plants,
     often with only screening as pretreatment, also have
     been applied successfully.

•    Effective management and monitoring are fundamental
     requirements for the successful operation of land
     application systems.

•    Land application systems, in many cases, have been
     started as an expedient, and available technology was
     not incorporated in the planned operation and manage-
     ment of the systems.

•    There is a paucity of quantitative information in the
     literature on the removal efficiencies of soil systems
     with respect to wastewater constituents.


•    Irrigation of croplands, forest, and landscaping with
     wastewater, either by spraying, ridge and furrow, or
     flooding techniques, is developed sufficiently so that
     general design and operational guidelines can be out-
     lined from currently available technology.

•    Provided that municipal wastewaters are adequately
     disinfected, there are no indications of serious
     health hazards caused by spray irrigation.

•    Irrigation is the most reliable land application ap-
     proach evaluated on the basis of direct wastewater
     recycling, renovation, long term use, and minimization
     of adverse environmental effects.


•    Overland flow, or treatment by spray-runoff (also
     known as "grass filtration"), has been demonstrated to
     be an effective technique for industrial wastewater
     treatment.  Further development is required to utilize
     its considerable potential for treatment of municipal

•    Overland flow has distinct advantages over irrigation
     for heavy, slightly permeable soils or rolling terrain

•    Nitrogen, suspended solids, and BOD removals are excel-
     lent, and adverse environmental effects appear to be
     minimal.  Systems have not been in operation long
     enough to determine long term effects or expectant
     period of use.


•    Infiltration-percolation is another feasible approach
     to land application of municipal or industrial waste -
     water, and several high rate systems have shown

•    Criteria for site selection, groundwater control, and
     management techniques for high rate systems need fur-
     ther development.

Infiltration-percolation, when practiced as a land
disposal approach, is less reliable than irrigation
from the standpoint of wastewater renovation and long
term use.

                        SECTION II

The following recommendations, which have been developed as
a result of this study, are grouped into three categories:
(1) implementation of land application projects, (2) devel-
opment of standard practices, and (3) research needs.


•    Land application approaches, where feasible, should be
     considered as alternatives in developing wastewater
     management plans.

•    When evaluating land application approaches for treat-
     ment as compared to conventional or advanced waste
     treatment processes, factors such as economics, sim-
     plicity of operation, and degree of renovation should
     be considered as well as the potential water reuse and
     the best use to be made of the land.

•    To gain public acceptance and support for land appli-
     cation projects, realistic implementation programs,
     including public relations, should be developed to
     accompany any planning activities for wastewater


•    General evaluation procedures for design and manage-
     ment of land application systems should be developed
     by the EPA to ensure successful system operations.

•    The operation of many existing systems can be enhanced
     through analysis of successful practices at other
     locations, evaluation of the key factors important to
     management, and initiation of monitoring of water
     quality changes throughout the system.

•    Design and operation practices in land application are
     so dependent on local conditions that a detailed de-
     sign or operations manual would likely stifle, rather
     than advance, the state-of-the-art.


Although a great deal is known, many technical questions
must be answered before wastewater renovation by land appli-
cation can become a scientific undertaking.  Research must
be initiated to define the environmental interactions of
soil, groundwater, air, and wastewater.  The priorities for
research by subject area, as established in this study, are
presented on the following list.

General Application

•    Climatic investigations should be undertaken to define
     simultaneously surface soil and ambient air tempera-
     tures for the United States.  Such information would
     be useful in determining the annual period in which
     vegetation and active bacterial metabolism might be
     maintained by wastewater application.

•    Virological investigations should be undertaken where
     municipal wastewater is applied by spraying.  Aerosol
     drift and infectivity and survival of viruses in aero-
     sols, on vegetation, and in soil need investigation.


•    The long term effects on soils, groundwater, and
     crops of (1) salt accumulation and (2) buildups of
     trace elements and heavy metals should be defined.

•    There are several large municipal wastewater irriga-
     tion systems that have been operating for 50 to 60
     years, and these could be investigated for long term

•    Studies on the effects of irrigation on the environ-
     ment, such as those underway at Pennsylvania State
     University and those planned for Muskegon, Michigan,
     should be continued.

•    Additional studies should be conducted to determine if
     crops grown under wastewater irrigation differ sub-
     stantially in quality from crops grown using fresh
     water irrigation and other sources of plant nutrients.

Overland Flow

•    Research on the application of the overland flow tech-
     nique to municipal wastewater such as that at Ada,
     Oklahoma, should be continued.

•    Field studies should be conducted to evaluate cold
     weather effects when using overland flow for indus-
     trial and municipal wastewater.

•    A correlation betwee'n BOD loading and treatment effi-
     ciency should be investigated for various climates,
     lengths of runoff travel, types  of grasses, and field

•    The mechanisms of nitrogen removal for overland flow
     should be studied.  Removals resulting from crop up-
     take, denitrification, and ammonia volatilization
     should be quantified, with the objective of optimizing
     nitrogen removal.

•    The applicability of using grasses, such as Italian
     rye and common bermuda grass, as cover crops under
     various climatic conditions should be investigated.
     Such grasses have proven successful for irrigation.

•    The effects of harvesting and removing hay for various
     grasses on BOD removal efficiency should be

•    The removal of phosphorus as affected by loading
     cycles, length of runoff travel, and type of grass
     should be investigated.


•    Operating procedures and conditions that are necessary
     for optimum nitrogen removal should be identified and

•    The effect of nitrification in the soil on BOD removal,
     TDS leaching, and the degree of  subsequent denitrifi-
     cation should be documented by field investigations.

•    Studies on the effect of vegetation on nitrification
     and denitrification in the soil  should be continued.

•    The removal efficiency for refractory organics should
     be determined for high rate loadings, and the health
     hazard of any such material reaching the groundwater
     should be investigated.

Environmental effects, such as increased leaching of
inorganic compounds and increased groundwater hardness,
should be investigated for high rate systems underlain
by limestone formations.  High organic loadings will
result in considerable carbon dioxide production which
may dissolve significant quantities of calcium and
magnesium as well as lower the pH.

                        SECTION III

Land application of wastewater is an old practice--it was
used by the Greeks in Athens and was begun in the United
States over 100 years ago.  Hundreds of communities through-
out the nation currently use one form or another of land
application with varying degrees of success.  The applica-
tion of wastewater to the land brings into play elements
of climate, air, land, vegetation, and water so that under-
standing and analysis of its many aspects requires a
multidisciplinary approach.

To gain a clearer and more comprehensive understanding of
the phenomena and problems associated with land application
of wastewater, the United States Environmental Protection
Agency in June 1972 awarded a contract to Metcalf § Eddy,
Inc., for an evaluation of the state-of-the-art.  For
this purpose a nationwide study was conducted of systems in
actual operation together with an extensive literature
review.  The information derived from the study was used to
categorize current types of systems and to provide data
necessary for system design and operation.


Current knowledge on land application of municipal and in-
dustrial wastewater has been gathered and is reported in
two volumes.

The purpose of this volume (Volume I) is to summarize the
state-of-the-art for engineers, planners, managers, and
decision makers.  Detailed engineering information and sup-
porting operational experiences are presented in an expanded
Project Report, printed separately as Volume II.  The infor-
mation presented in these two volumes is intended as a
report of current knowledge--not as a statement of design

The scope of this report is limited to a presentation and
discussion of those methods of land application of waste-
water that use the soil system to provide renovation to the
wastewater.  Thus, deep well injection and surface evapora-
tion ponds are not considered in depth.  Land application
of municipal or industrial waste sludge was specifically
omitted from the study.  The report contains sufficient in-
formation on land application to provide a basis for
effective management decisions.

Separate sections are included in this volume on land appli-
cation approaches, wastewater and site characteristics,
system design and operation, environmental effects, public
health considerations, and cost evaluations.


Information Sources

Information was gathered from  (1) the literature,  (2) site
visits and interviews, and (3) previous experience.  The
literature has been reviewed extensively, and abstracts of
articles reviewed will be published separately by the EPA.
Cited reports, studies, and other pertinent literature, have
been arranged alphabetically, numbered sequentially, and
listed in Section X.  Where reference is made to this
material in the text, the appropriate number is enclosed
in brackets.

Actual on-site visits were made to nine installations in
the United States and one in Canada.  The information
obtained was given to the American Public Works Association
(APWA) which, in turn, cooperated in making available data
from their fact-finding survey.  That survey was conducted
during the same time period of this study and covered
several hundred United States sites and several foreign
ones with the object of establishing an inventory of prac-
tices at selected existing facilities.  In addition, infor-
mation on several sites was available prior to the conduct
of this study.  A listing of all sites visited and used
in this study plus those contacted by APWA are given in
Section XIII.

Definition of Key Terms

Because several key terms will be used extensively in this
report, they will be defined here.  A complete glossary and
list of abbreviations is in Section XII.

Irrigation--Application of water to the land to sustain the
growth of plants.

Overland flow--Wastewater treatment by spray-runoff (also
known as "grass filtration") in which wastewater is sprayed
onto gently sloping, relatively impervious soil planted to
vegetation.  Biological treatment occurs as the wastewater
flow contacts biota in the ground cover vegetation.

Infiltration-percolation--An approach to land application
in which large volumes of wastewater are applied to the
land, infiltrate the surface, and percolate through the
soil pores.

Loading rates--The average amount of liquid or solids
applied to the land over a fixed time period taking into
account periodic resting.

Application rates--The rates at which the liquid is dosed
to the land, usually in in./hr.

Conventional wastewjiter^ j:reatment - -Reduction of pollutant
concentrations in" wTTstewater by physical, chemical, or
biological means.

Sewage farming--Originally involved the transporting of
sewage into rural areas for land disposal.  Later practice
included reusing the water for irrigation and fertilization
of crops.


Wastewater application to the land was practiced in Athens
in the B.C. period [34] and the recorded history of irriga-
tion has been traced to Germany in the sixteenth century,
A.D. [11].  The practice of sewage farming spread to
England in the 1700s and to the United States in the 1870s
[46].  Rafter [45] and Mitchell [38] present data on
European practice in England, at Paris, France, at Berlin,
Germany, and at Moscow, Russia, in the 1890s to 1920s.
In surveys conducted in the United States in 1895 [46] and
1935 [20], over 100 systems were found across the country.
Historical data on a few of the more notable operations in
the world are listed in Table 1.  Unless otherwise noted
the data are for the dates given in the first column of the
table.  Many of these facilities, including the ones at
Mexico City and Melbourne, Australia, are still in

          Table 1.   Historical  Data  on Sewage  Farming





Non-United States
Bunzlau, Germany
Croydon-Beddington, England
South Norwood, England
Berlin, Germany
Leamington Springs, England
Birmingham, England
Melbourne, Australia
Melbourne, Australia
Mexico City, Mexico
Paris, France
Cape Town, South Africa
United States
Augusta, Maine
Pullman, Illinois0
Cheyenne, Wyoming
Pasadena, California
San Antonio, Texas
Salt Lake City, Utah
Bakersfield, California
Vineland, New Jersey

Descrip .^n

Sewage f.- -m
Sewage fa.-m
Sewage farm
Sewage farm
Sewage farm
Sewage farm
Overland flow






loading ,
in . /wk





a.  Data for 1926.
b.  Data for 1971.
c.  Abandoned around 1900.
d.  Data for 1972.

                        SECTION IV

Irrigation, overland flow, and infiltration-percolation are
the three basic approaches to land application.  These
three approaches are shown schematically on Figure 1.  The
wastewater may be applied to the land by spraying or sur-
face techniques in any of the three approaches.  Municipal
wastewater, usually treated to secondary quality, has been
applied mainly by irrigation.  Some municipalities have
practiced infiltration-percolation; however, the only munic-
ipal installation identified in this study using overland
flow is at Melbourne, Australia [22].  Industrial waste-
water, generally screened or settled, has been applied
using all three approaches with the choice usually depending
upon the soil type of the nearby land.  Food processing,
pulp and paper, dairy, and tannery wastewaters have been
used for irrigation and infiltration-percolation.  The
few overland flow systems in the United States are for
food processing wastewaters.

The major characteristics of irrigation, overland flow, and
infiltration-percolation are listed in Table 2.  A discus-
sion of each characteristic is included for each approach.
Factors involved in selecting among these approaches are
presented following the discussion of each approach.


Irrigation is the most widely used type of land application
with over 300 U.S. communities practicing this approach,
according to the 1972 Municipal Wastewater Facilities In-
ventory conducted by the EPA.  Aspects of irrigation covered
in the following discussion include the controlling factors
in site selection and design, the methods of irrigation,
loading rates, management and cropping practices, and
the expected wastewater renovation or removals of wastewater

SURFACE          ' vJA
                                (a) IRRIGATION
                                           GRASS AND VEGETATIVE  L I TTER
SLOPE  2-6'
                                (b) OVERLAND  FLOW
                                 SPREADING  BASIN
                                                  SURFACE APPLICATION
                                                            NEW  WATER TABLE

                                                            OLD  WATER TABLE-
                          (c) INFILTRATION-PERCOLATION

                                  FIGURE  1
                      LAND  APPLICATION  APPROACHES

           Table  2.   Comparative  Characteristics  of
    Irrigation, Overland Flow, and Infiltration-Percolation
Liquid loading rate
Annual application

0.5 to 4 in./wk
2 to 8 ft/yr
Type of Approach
Overland flow
2 to 5.5 in'./wk
8 to 24 ft/yr

4 to 120 in./wk
18 to 500 ft/yr
Land required for
1-mgd flow


Probability of
influencing ground-
water quality

Needed depth to

Wastewater lost to:
140 to 560 acres
plus buffer zones

Spray or surface
Moderately per-
meable soils with
good productivity
when irrigated

About 5 ft
                    evaporation or
                    deep percolation
46 to 140 acres
plus buffer zones

Usually spray
                                    Slowly permeable
                                    soils such as clay
                                    loams and clay
                Surface discharge
                dominates over
                evaporation and
2 to 62 acres
plus buffer zones

Usually surface
                  Rapidly permeable
                  soils, such as
                  sands, loamy sands,
                  and sandy loams

                                  About 15 ft
                  Percolation to
a.  Adapted from [62].

b.  Irrigation rates of 4 in./wk are usually seasonal; yearly maximum loads of 8 ft/yr
   would average about 2 in./wk.
 Factors in Site  Selection

 The  major  factors  involved in  site selection  are:  the type,
 drainability, and  depth  of soil;  the nature,  variation of
 depth, and quality of groundwater; the  location, depth, and
 type of underground formations;  the topography;  and  con-
 siderations of public access to  the land.  Climate is  as
 important  as the land in the design and operation of irri-
 gation systems.  In site selection, however,  it  is not a
 variable since most economically feasible sites  will be
 located within a limited transmission distance from  the

 The  major  factors  and generalized criteria for site  selec-
 tion are listed  in Table 3.  Soil drainability is perhaps
 the  primary factor because, coupled with the  type of crop
 or vegetation selected,  it directly affects the  liquid
 loading rate.  A moderately permeable soil capable of

         Table  3.   Site Selection  Factors
       and Criteria for Effluent  Irrigation
Soil type
Soil drainability
Soil depth
Depth to groundwater
Groundwater control
Groundwater movement
Underground formations
Distance from source
of wastewater
Loamy soils preferable but  most
soils from sands to clays  are

Well drained soil is preferable;
consult experienced agricultural

Uniformly 5 to 6 ft or more
throughout sites is preferred.

Minimum of 5 ft is preferred.
Drainage to obtain this minimum
may be required.

May be necessary to ensure
renovation if water table is less
than 10 ft from surface.

Velocity and direction must be

'Up to 15 percent are acceptable
with or without terracing.

Should be mapped and analyzed
with respect to interference
with groundwater or percolating
water movement.

Moderate isolation from public
preferable, degree dependent on
wastewater characteristics,
method of  application, and crop.

A matter of economics.

infiltrating approximately 2 in,/day or more on an inter-
mittent basis is preferable.  In general, soils ranging
from clay loams to sandy loams are suitable for irrigation.
Soil depth should be at least 2 feet of homogenous material
and preferably 5 to 6 feet throughout the site.  This
depth is needed for extensive root development of some
plants and for wastewater renovation.  For cropland, agri-
cultural extension service advisers or adjacent farmers
should be consulted.  For forest or landscape irrigation,
university specialists should be consulted.

The minimum depth to groundwater should be 5 feet to ensure
aerobic conditions [50] .  If the native groundwater is
within 10 to 20 feet of the surface and site drainage is
poor, control procedures, such as underdrains or wells,
may be required.  If the groundwater quality is signifi-
cantly different from the renovated water quality, control
procedures may again be necessary to prevent intermingling
of the two waters.

For crop irrigation, slopes should be limited to about 10
percent or less depending upon the type of farm equipment
to be used.  Forested hillsides up to 30 percent in slope
have been spray irrigated successfully [53] .

A suitable site for wastewater irrigation .would preferably
be located in an area where contact between the public and
the irrigation water and land is controlled.  Landscape
irrigation, however, often makes this condition difficult.

Methods of Irrigation

There are three basic methods of effluent irrigation:
spray, ridge and furrow, and flood.  Spray irrigation
may be accomplished using a variety of systems from portable
to solid-set sprinklers [40] .  Ridge and furrow irrigation
consists of applying water by gravity flow into furrows.
The relatively flat land is groomed into alternating ridges
and furrows with crops grown on the ridges.  Flood irriga-
tion is accomplished by inundation of land with several
inches of water.  The type of irrigation system to use
depends upon the soil drainability, the crop, the topography,
and the relative economics.

Loading Rates

Important rates are liquid loading in terms of inches
per week, and nitrogen loading in terms of pounds per acre
per year.  Organic loading rates are less important pro-
vided that an intermittent application schedule is followed.

Liquid loadings may range from 0.5 in./wk to 4.0 in./wk de-
pending on the soil, crop, climate, and wastewater
characteristics.  Crop requirements generally range from
0.2 to 2.0 in./wk, although a specific crop's water needs
will vary throughout the growing season.  Typical liquid
loadings are from 1.5 to 4.0 in./wk.  Although wastewater
irrigation rates have ranged in some cases up to 7 or
8 in./wk, the upper limit for irrigation, on the basis of
this study, should be 4 in./wk.  Therefore, the division
between irrigation and infiltration-percolation systems as
defined in this study is 4 in./wk.

Nitrogen loading rates have been calculated because of
nitrate buildup in soils, underdrain waters, and
groundwaters.  To minimize such buildup, the pounds of
total nitrogen applied in a year should not greatly exceed
the pounds of nitrogen removed by crop harvest.  For ex-
ample, an effluent containing 20 mg/L of nitrogen applied
at 5 ft/yr would equal a nitrogen loading rate of 270
Ib/acre/yr.  If the irrigated crop takes up only 150 lb/
acre/yr, most of the excess nitrogen will leach to the
subsoil and ultimately to the groundwater.  In most cases,
with loamy soils, the permissible liquid loading rate
will be the controlling factor; however, for more porous,
sandy soils the nitrogen loading rate may be the controlling

Management and Cropping Practices

Crop selection can be based on several factors:  high water
and nutrient uptake, salt or boron tolerance, market value,
or management requirements.  Grasses with high year-round
uptakes of water and nitrogen and low maintenance require-
ments are popular choices.  To ensure the die-off of anaero-
bic bacteria, an aerobic zone in the soil is necessary.  A
drying period ranging from several hours each day to several
weeks is required to maintain aerobic soil conditions.
The length of time depends upon the crop, the wastewater
characteristics, and the length of the application period.
A ratio of drying to wetting of about 3 or 4 to 1 should
be considered a minimum.

Wastewater Renovation

Renovation of the wastewater occurs generally after passage
through the first 2 to 4 feet of soil.  Monitoring to deter-
mine the extent of renovation is generally not practiced;
when it is practiced, however, removals are found to be on
the order of 99 percent for BOD, suspended solids, and fecal
coliforms.  As irrigation soils are loamy with considerable
organic matter, the heavy metals, phosphorus, and viruses

are retained in the soil by adsorption and other mechanisms.
Nitrogen is taken up by plant growth, and if the crop is
harvested, the removals can be on the order of 90 percent.


Overland flow or spray-runoff (see Figure 1) has been used
for some time at Melbourne, Australia, where it is known
as grass filtration.  Although it is being tried experi-
mentally on municipal wastewater at Ada, Oklahoma, it
has been more completely developed for use in the United
States on food processing wastewater.  Site selection fac-
tors, design loadings, management practices, and renovation
to be expected will be discussed here.

Factors in Site Selection

Soils with limited drainability, such as clays and clay
loams, are suited to overland flow.  The land should have a
slope between 2 and 6 percent [10] and a very smooth sur-
face so that the wastewater will flow in a sheet over
the ground surface.  Slopes greater than 6 percent can be
used successfully but may introduce problems, such as
erosion, and difficulties in using farm machinery.  Grass
is planted to provide a habitat for the bacteria which
provide the renovation.  As runoff is expected, a suitable
means of final disposal should be provided.

Because groundwater will not likely be affected by overland
flow, it is of minor concern in site selection.  The ground-
water table should be deeper than about 2 feet, however, so
that the root zone is not waterlogged.

Climatic constraints have not been thoroughly tested, but
industrial systems are being operated in California, Texas,
Ohio, Pennsylvania, Indiana, and Maryland.  In an industrial
system designed in 1972 at Glenn, Michigan, an attempt will
be made to use overland flow when the ground is frozen.  At
Melbourne, Australia, overland flow is used during the
mild winters when evaporation and rainfall are low [30].

Design Loadings

Systems are generally designed on the basis of liquid load-
ing rates, although an organic loading or detention time
criterion might be developed in the future.  The process is
essentially biological with a minimum contact time between
bacteria and wastewater required for adequate treatment.
Liquid loading rates used in design have ranged from 2.5 to
5.5 in./wk, with a typical loading being 4 in./wk for food
processing wastewater.  At Ada, Oklahoma, the optimum

loading for comminuted municipal wastewater has been around
4 in./wk, while at Melbourne, Australia, the loading rate
is 5.2 in./wk for untreated municipal wastewater.

Management Practices — Important management practices are:
maintaining the proper hydraulic loading cycle, maintaining
an active biota and a growing grass, and monitoring the per-
formance of the system.  Hydraulic loading cycles, or
periods of application followed by resting, have been found
to range from 6 to 8 hours of spraying followed by 6 to
18 hours of drying for successful operations.  Periodic
cutting of the grass with or without removal is important,
but the effects on organic oxidation have not been fully
demonstrated.  Monitoring is needed to maintain loading
cycles at optimum values for maximum removal efficiencies.

Wastewater Renovation — Overland flow systems at Melbourne,
Australia,and Ada,(Oklahoma, using municipal wastewater,
and at Paris, Texas, using industrial wastewater, have been
monitored to determine removal efficiencies.  The expected
ranges based on results at these sites are BOD and suspended
solids removals of 95 to 99 percent, nitrogen removals of 70
to 90 percent, and phosphorus removals of 50 to 60 percent.
Removal of solids and organics is by biological oxidation
of the solids as they pass through the vegetative litter.
Nutrient removal mechanisms include crop uptake, biological
uptake, denitrification, and fixation in the soil.


The infiltration-percolation approach, illustrated in
Figure 1, has been used with moderate loading rates (4 to
60 in./wk) as an alternative method to effluent discharge
into surface waters.  High rate systems (5 to 10 ft/wk)
have been designed for groundwater recharge.  These latter
systems have been carefully designed and monitored, and
most of this discussion, concerning site selection, design
loadings, management practices, and wastewater renovation,
will deal with them.

Factors in Sit^e Selection

Soils with infiltration rates of 4 in./day to 2 ft/day, or
more, are necessary for successful use of the infiltration-
percolation approach.  Acceptable soil types include sand,
sandy loams, loamy sands, and gravels.  Very coarse sand
and gravel is not ideal because it allows wastewater to
pass too rapidly through the first few feet where the
major biological and chemical action takes place.

Other factors of importance include percolation rates,
depth, movement and quality of groundwater, topography, and
underlying geologic formations.  To control the wastewater
after it infiltrates the surface and percolates through the
soil matrix, the subsoil and aquifer characteristics must
be known.  Recharge should not be attempted without spe-
cific knowledge of the movement of the water in the soil
system and the groundwater aquifer.

Design Loadings^

As indicated, there are two ranges of liquid loading rates,
moderate and high, depending upon the loading objective.
For direct recycling of wastewater to the land by
infiltration-percolation, liquid loading rates range from
4 to 60 in./wk [26].  Organic loading rates are generally
of secondary importance for moderate rate systems.

For high rate systems, liquid loadings range from 5 to
10 ft/wk.  Organic loading rates range from 3 to 15 tons
of BOD/acre/yr.  Municipal high rate infiltration-
percolation systems generally pretreat the wastewater
to secondary quality to maintain high liquid loading rates.
Industries have tended to rely more on the assimilative
capacity of the soil, and thus have generally used pre-
treatment only to avoid operational problems.

Management Practices

Important management practices include maintenance of
hydraulic loading cycles, basin surface management, and
system monitoring.  Intermittent application of wastewater
is required to maintain high infiltration rates, and the
optimum cycle between inundation periods and resting peri-
ods must be determined for each individual case.  Basin
surfaces may be bare, covered with gravel, or vegetated.
Each type requires some maintenance and inspection for a
satisfactory operation.  Monitoring, especially of ground-
water levels and quality, is essential to system management

Wastewater Renovation

Removals of constituents by the filtering and straining
action of the soil are excellent.  Suspended solids, fecal
coliforms, and BOD are almost completely removed in most
cases.  Nitrogen removals are generally poor unless specif-
ic operating procedures are established to maximize
denitrification.  Phosphorus removals range from 70 to
90 percent depending on the physical and chemical charac-
teristics of the soil that influence retention of


There are several other approaches to land application, in-
cluding subsurface leach fields, deep well injection, and
evaporation ponds.  Such techniques are generally limited
in their applicability.  Leach fields are prevalent in rural
areas for small systems and are likely to remain so.  Deep
well injection provides no substantial renovation to the
wastewater.  Pretreatment must be to a high quality, and
geologic conditions must be such that the water will not
spread to other aquifers.  Evaporation ponds also have
limited applicability because of the large land require-
ments and climatic constraints.


Reliability of land application involves considerations of
long term use, wastewater renovation, and minimization of
adverse environmental impacts.  Unlike mechanical treatment
facilities, land application facilities do not have a fixed
expected useful life.  The useful life depends upon factors
such as the management, the soil, the climate, and the
wastewater characteristics.  Also, changing land use needs
and wastewater management objectives affect the expected
life of a system.  These factors, as they affect the relia-
bility of irrigation, overland flow, and infiltration-
percolation, will be discussed here.


Wastewater irrigation has proven to be reliable in terms of
long useful life.  Examples are the systems at Cheyenne,
Wyoming, operating since 1881; at Fresno, California, oper-
ating since 1891; and at Bakersfield, California, operating
since 1912.

As indicated previously, wastewater renovation as a result
of irrigation is quite high.  With proper management, degra-
dation of groundwater and health risks can be avoided.
Irrigation has had many positive effects on the environment,
such as improving soil conditions and providing wildlife
habitats.  It can therefore be concluded that irrigation
is the most reliable approach to land application of
wastewater of the methods investigated.

Overland Flow

Less is known about the useful life of an overland flow
system than of an irrigation system.  The system at
Melbourne, Australia, has been operating successfully for

many years as a wintertime alternative to irrigation.  The
oldest operating system in this country, however, has been
treating industrial wastewater for less than 20 years.
From the evidence in the literature, an indefinite useful
life may be possible if effective management is provided.

Removal efficiencies are also quite good for overland flow.
As it is a biological process, a period of intermediate
treatment will occur before the biota are fully established.
Renovation of wastewater by overland flow is only slightly
less .complete than that for irrigation, the major exception
being a rather low removal of phosphorus.

Adverse environmental effects from overland flow systems
should be minimal.  As a runoff flow is created, it must
be either stored and reused or discharged to a surface
watercourse.  Because infiltration into the soil is slight,
the chances of affecting groundwater quality are minimal.
Buildups of salts may occur over time, depending on the
operation, but these would have little effect on other
aspects of the environment.


The useful life of an infiltration-percolation system, will
be shorter, in most cases, than that for irrigation or over-
land flow.  This is caused by higher loadings of inorganic
constituents, such as phosphorus and heavy metals, and the
fact that these constituents are fixed in the soil matrix
and not positively removed.  Therefore, exhaustion of the
fixation capacity for phosphorus and heavy metals will be
a function of the loading rate and the fixation sites
available.  At Lake George, New York, phosphorus retention
on the basis of recent monitoring in some percolation beds
appears to have been exhausted through 10 feet of soil.
The system had been operating about 35 years at moderate
rates of 7 to 15 in./wk [3].

The degree of wastewater renovation achieved by
infiltration-percolation varies considerably with the soil
characteristics and management practices.  Nitrogen re-
movals up to 80 percent have been obtained by careful man-
agement of the hydraulic loading cycle at Flushing Meadows,
Arizona (2 to 3 weeks'  wetting, 2 weeks' drying).  Overall
nitrogen removal, taking into account the high nitrate
concentration flushed to the groundwater at the beginning
of inundation, averages 30 percent [6] .  Removals of phos-
phorus and heavy metals are also generally less than for

From  the  standpoint  of  environmental effects,  infiltration-
percolation has  demonstrated  the least amount  of reliability
of  the  three approaches.  Most systems that have been moni-
tored and managed properly, however, are quite reliable in
this  regard.   Infiltration-percolation also has the advan-
.tage  of providing a  tertiary  level of treatment at a rela-
tively  low cost.


Irrigation, overland flow, and infiltration-percolation have
many  common aspects,  but many different factors must be con-
sidered in selecting among them.  Approach selection will
be  discussed from the standpoint of  (1) the 1972 Federal
Amendments to  the Water Pollution Control Act  of 1970,
(2) wastewater management objectives, and  (3)  technical

1972  Federal Amendments

Land  application was given a  substantial role  in the Federal
Water Pollution  Control Amendments of 1972.  Elimination
of  the  discharge of  pollutants to navigable waters by 1985
is  the  stated  goal of those amendments.  Land  treatment
and the recycling of potential wastewater pollutants through
irrigation must  be given due  consideration in wastewater
management plans.

Wastewater Management Objectives

Objectives for wastewater management have been listed in
Table 4 along with the  capabilities of each approach in
meeting them.  There are other possible objectives and
those that might be  specific  to industrial wastewaters have
not been  included.   As  indicated, irrigation provides con-
siderable renovation; however, the major portion of the
wastewater applied is lost to evapotranspiration.  Unless
excess  irrigation water is applied and underdrains or re-
covery  wells are used,  the approach is impractical as a
means of  reclaiming  wastewater.

Technical Factors

Physical  aspects of  the available land, such as soil type,
underground formations, and ground slope, will influence
the approach selection.  Other technical factors include
wastewater characteristics and flow rates, climate, and
whether the flow remains constant throughout the year.  For
seasonal  flows,  such as those from canneries,  the selection
of  the  overland  flow system,  like any biological system,

        Table  4.   Comparison of  Irrigation, Overland
           Flow,  and Infiltration-Percolation for
                     Municipal Wastewater
                                       Type of approach
                                        Overland flow
 Use as a treatment process with
 a recovery of renovated water

 Use for treatment beyond
   1. For BOD and suspended
50 to 601
Up to 904

solids removal
For nitrogen removal
For phosphorus removal
to grow crops for sale
as direct recycle to
to recharge groundwater
in cold climates
Up to 90 4a
Up to 904
 a. Dependent upon crop uptake.
 b. Conflicting data—woods irrigation acceptable, cropland irrigation marginal.
 c. Insufficient data.
must  take into account an annual startup period.  Soil
classification, an important  independent variable, has been
graphed against liquid loading rates  as the  dependent
variable.   The resultant combinations have been blocked out,
as  shown on Figure 2,  for the typical ranges  for each  land
application approach.   These  are not  intended to be  a  de-
sign  guideline but rather a general aid in the process of
approach selection.

                         SOIL TYPE

                       FIGURE  2

                         SECTION V

Knowledge of the characteristics of both the wastewater to
be applied and the site where the application will take
place is critical to successful design and operation of
land application systems.  In this section, municipal and
industrial wastewater characteristics that affect land ap-
plication methods will be discussed.  The factors involved
in site selection for individual land application approaches
have been discussed in Section IV.  The discussion here
will present overall characteristics of sites successfully
used for land application.


The characteristics of municipal and industrial wastewater
may be classified as physical, chemical, and biological.
Municipal wastewater characteristics are listed in Table 5
for (1) untreated wastewater, (2) a typical secondary efflu-
ent, and (3) effluents that have been applied to the land.
The degree of pretreatment normally given by secondary
treatment processes can be seen by comparing columns 1 and
2.  A discussion of the effects of conventional wastewater
treatment on characteristics is presented at the end of
this subsection.

Industrial wastewaters contain many of the constituents
found in municipal wastewaters, but their characteristics
vary widely by industry, by product, and even by processing
technique.   A typical industrial wastewater does not' exist;
however, ranges or maximum values of characteristics of
industrial wastewaters that have been successfully applied
to the land are listed in Table 6.  Important characteris-
tics will be discussed here by classification.

Physical Characteristics

The most important physical characteristic of wastewater is
its total solids content.  The solids include floating,
suspended,  colloidal, and dissolved matter.

Table 5.  Municipal Wastewater Characteristics
mg/L (except as noted)
Total solids
Total suspended
Total dissolved
pH, units
Total nitrogen
Nitrate -nitrogen
Ammonia -nitrogen
Total phosphorus
Alkalinity (CaCOj)
Sodium adsorption
Coliform organisms,
MPN/100 ml
Sources :
Column 1 — Medium s
Column 2 - [2].
Column 3 — Range of








trength [34] .
values obtained from site
Actual quality
applied to land




visits .

            Table  6.   Characteristics of Various
         Industrial Wastewaters  Applied to the Land
         Constituent       processing   Pulp and paper  Dairy

     BOD, rag/L             200-4,000     60-30,000     4,000

     COD, mg/L             300-10,000

     Suspended solids, mg/L 200-3,000     200-100,000

     Total fixed
dissolved solids, rag/L
Total nitrogen, mg/L
Temperature , deg F

The suspended  solids  are  very important because they have
a tendency  to  clog  the  soil pores and coat the land surface.
Other physical characteristics are temperature, color,
and odor.   Temperature  is not a great problem for municipal
wastewater  effluents  because they have a fairly even tem-
perature, 50 deg F  to 70  deg F, which is not harmful to
soil or vegetation.   High temperature (above 150 deg F)
industrial  wastewaters, such as spent cooking liquors
from pulping operations,  can sterilize the soil, thus
precluding  the  growth of  vegetation and reducing the reno-
vative capacity of  the  soil mantle.

Color is of minor importance in municipal wastewater; how-
ever, some  industrial wastewaters (spent sulfite liquor)
have significant color, which can be transmitted through
the soil [5].

Odors in wastewater are caused by the anaerobic decomposi-
tion of organic matter.   Although hydrogen sulfide is the
most important  gas  formed from the standpoint of odors,
other volatile  compounds  such as indol, skatol, and mercap-
tons also cause noxious odors.   These odors are often
released to the atmosphere  by spraying or aerating.

Chemical Characteristics

Important chemical characteristics have been listed in
Table 5.  IDS  (total dissolved solids) are important be-
cause, at least for the fixed or mineral IDS, the soil does
not provide a positive long term removal mechanism.  With
irrigation, evaporation will concentrate the salts in the
soil, and the subsequent high concentrations may be injuri-
ous to plants, or may be leached to the groundwater.

The pH and alkalinity are generally of concern only for in-
dustrial wastewater.  For example, cannery wastewater
often exhibits wide fluctuations in pH, and neutralization
may be required.

Organic matter as measured by the COD and degradable organ-
ics as measured by the BOD will be effectively removed by
land application.  If the COD is much greater than the BOD,
or if the wastewater contains organic matter that is starchy
or fibrous, the organics may build up and cause clogging of
the soil pores.

Nitrogen is important because, converted to the nitrate
form, it can pass easily through the soil matrix.  Total
nitrogen is the sum of the organic, ammonium, nitrite, and
nitrate form concentrations.  Nitrogen can be removed by
land application through plant uptake with harvest and by

Phosphorus and heavy metals are easily fixed in most soils
by precipitation and adsorption.  Sandy soils provide fewer
sites in the soil matrix for adsorption; hence phosphorus
retention capacities are relatively short.  Concentrations
of heavy metals, such as copper and zinc, can build up to
phytotoxic levels in time, depending on the soil type and
method of operation.

High sodium concentrations relative to calcium and magnesium
concentrations can cause deflocculation of clay soils and
reduce the permeability.  For such soils "hard water makes
soft land and soft water makes hard land" [63].

Biological Characteristics

Municipal wastewater contains many bacteria and viruses.
Industrial wastewaters are not free of microorganisms, but
usually do not have enteric bacteria.  The presence of
enteric pathogens is often ascertained by testing for the
coliform group.  E. Coli (Escherichia coli)  are used as
indicator organisms because they are present in the diges-
tive tract of man and are more numerous and more easily

tested for than pathogenic organisms.  Aerpbacter, a common
soil bacteria, exhibits many of the same responses as
E. Coli, and the differences must be tested for using the
confirmed test for coliforms.  If fecal coliforms are not
distinguished from soil coliforms, the efficiency of the
soil system in removing fecal coliforms will be

Effects of Pretreatment on Wastewater Characteristics

Conventional wastewater treatment begins with preliminary
operations, such as screening and sedimentation.  Effluent
from these operations, referred to as primary, has had the
bulk of large objects, grit, and floatable and settleable
material removed.  Sedimentation typically removes 50 to
65 percent of the suspended solids, 25 to 40 percent of the
BOD, and many pollutants such as Ascarjs eggs.

Secondary treatment consists of biological oxidation by
activated sludge or trickling filters, or physical-chemical
treatment by precipitation, filtration, and carbon
adsorption.  Effluent is low in suspended and organic mat-
ter and readily disinfected.  Most dissolved inorganics are
not affected by secondary treatment.  Secondary treatment
does provide an additional removal of bacteria and viruses
by flocculation and secondary sedimentation.

Disinfection, the selective destruction of disease-causing
organisms, may be accomplished using heat, ozone, bromine,
iodine, or, most commonly, chlorine.  Adequate disinfection
requires complete and rapid mixing and a minimum contact
time.  The presence of suspended solids hinders the process
of disinfection; therefore, secondary effluent is more
readily disinfected than primary effluent.  The number
of coliform organisms can be reduced by disinfection tech-
niques from 10" organisms per 100 ml to less than 2.2 orga-
nisms per 100 ml.


Important site characteristics for land application systems
are climate, soil, topography, geologic formations, and


In most land application systems, the vegetation cover is a
major factor in the success of the system.  Both the rate
of growth of vegetation and the rate of decomposition of
organics in the effluent are regulated, in large part, by
the energy available.  Most places in the United States have

sufficient energy for the development of a good ground
cover of vegetation, although low levels of energy receipts
in the winter in northern areas, with resulting cold tem-
peratures , will limit the rate of decomposition of any
solids removed from the effluent.

It has been possible to subdivide the United States into
5 zones or areas in which climatic conditions pose quite
similar constraints to the operation of land application
systems (Figure 3).  In preparing the map, an effort was
made to simplify distribution patterns; where possible,
state boundaries were used for ease in setting zone bound-
aries even though climates seldom change at such political

Zone A, which covers California except for the extreme
southeastern part, delineates the unique Mediterranean cli-
matic region with its marked seasonal pattern in
precipitation.  Average annual precipitation is about 15 to
25 inches confined generally to the 6 months from November
to April; practically no precipitation falls in the other
6 months of the year.  Temperatures are mild in winter
and hot in summer so that there is adequate energy in almost
all seasons for plant growth.  Storage of effluent due to
freezing will not be necessary but may be desirable to maxi-
mize summer application rates or to make the addition of
nutrients contained in wastewater correspond to crop

Zone B covers southwestern United States, an area of very
hot, arid climates.  Winter storage of effluent should not
be a concern although there will be a real problem due to
the lack of sufficient moisture for vegetation growth in
all seasons unless irrigation is available.  There may also
be problems of salt in the soil if brackish water is used
in irrigation or constitutes a significant portion of the

Zone C covers primarily the states identified as the Mid-
and Deep South as well as the western portions of Washington
and Oregon.  In general, precipitation varies from 40 to
60 inches during the year, and temperatures range from the
low 40s in winter to the low 80s in summer, except for the
Washington-Oregon area which experiences mild summers and
winters.  Twelve-month operation of land application systems
is possible from the standpoint of temperature.  However,
the well distributed and relatively high precipitation
eliminates the need for extended periods of irrigation
which are desirable from the standpoint of wastewater

I n
I '
            CLIMATIC ZONES
                 DRY SUMMER - MILD, WET WINTER
            B   ARID CLIMATE - HOT,  DRY
                                                        FIGURE 3

Zone D covers the middle tier of states running eastward
from Colorado to southern New England and the eastern por-
tions of Washington and Oregon.  The climates are marked
by moderately cold winters (average temperatures in the
20s), hot summers (average temperatures in the mid-70s),
and precipitation well distributed through the year.  Some
irrigation might be needed in the western portion for vege-
tation development but little would be needed in the east.
Winter temperatures are cold enough so that effluent stor-
age for several months or so may be necessary.

Zone E covers the northernmost tier of states.  Very cold
winters with warm summers and adequate moisture for vegeta-
tion exist.  Winter operations are quite limited because
the cold winter temperatures, with ice and snow, require
the storage of effluent for anywhere from 3 to 6 months.

Because the water needs of plants are affected by the
air temperature, humidity, inclination of the sun, and
wind velocity, climate will affect irrigation and overland
flow more than infiltration-percolation.  The United States
Weather Bureau collects and publishes a great deal of
important climatic data and should be consulted for local


The important soil characteristics are its drainability,
which is related to soil structure and texture as well as
geological constraints, and soil renovative capacity, which
is related to texture and chemical characteristics.

Drainability — Drainability is the ability of a soil to
allow water to infiltrate the surface and percolate through
the soil pores.  Light, coarse textured, granular soils are
usually well drained and are most suitable for infiltration-
percolation.  On the other hand, heavy, fine textured soils,
such as clays, are usually poorly drained and are most suit-
able for overland flow.

Soils may be considered well drained if an application of
2 in./day will infiltrate into the ground within 24 hours.
In determining drainability local farmers, agronomists, or
agricultural extension service experts should be consulted.
The standard percolation test results should not be relied
upon for design purposes because they represent conditions
of constant inundation, in a localized pit, without taking
into account lateral flow within the soil.

Renovation Capacity — Nearly all soil systems are efficient
in removing organic matter.  This removal is a result of

the filtering action of the soil followed by biological
oxidation of the organics.  Fine textured soils, such as
clays, and soils with considerable organic matter, such as
loams, will also retain wastewater constituents through
mechanisms such as adsorption, precipitation, and ion
exchange.  The fixation (includes all three mechanisms men-
tioned) capacity of a soil can be determined in laboratory
or pilot investigations.  Excellent sources for detailed
descriptions of the renovation capacity of soil are Bailey
[48] and McGauhey and Krone [28].  The Soil Conservation
Service of the U.S. Department of Agriculture has extensive
soil maps that include data on physical characteristics
such as soil type and texture to a depth of 5 feet.

Topography and Geologic Formations

Topography will influence the land application approach and
the method of wastewater application.  Rolling hills can
be used for overland flow or spray irrigation depending
on the soil.  Infiltration-percolation generally requires
flat land, although in Wisconsin a ridge and furrow system
was carved into a 5 percent slope using a series of
terraces [4] .

Cropland irrigation requires relatively flat land in order
to use farm machinery, but forested hillsides up to 30
percent in slope have been used  for land application by
spraying [53].

The drainability of a soil can be restricted or enhanced by
underground formations.  Underlying rock or impermeable
layers may serve as a barrier to percolating water.  On the
other hand, a fine textured soil can be underlain by sand
and gravel layers or fractured limestone layers which
are more permeable than the top soil.  As indicated in
Section IV, infiltration-percolation site selection requires
the thorough mapping of underlying formations.  The U.S.
Geological Survey is the major source for these data.


The depth, movement, and quality of groundwater are impor-
tant considerations in determining site characteristics.
For infiltration-percolation the location and possible con-
trol by pumping of aquifers are major factors in site
selection.  As indicated in Section IV, the chances of irri-
gation and overland flow affecting groundwater quality are
moderate and slight, respectively.  The major concern with
irrigation is that the groundwater level be maintained below
the root zone to protect the vegetation.  A minimum depth
to groundwater has not been determined for overland flow.

                        SECTION VI

Land application systems, in many cases, have been started
as an expedient and available technology did not contribute
to the planned operation of the system.  This is especially
true for moderate sized and small systems.  Those features
that have proved successful at different locations and are
worthy of note are discussed in this section.


Irrigation systems in operation in 1972 range from new spray
systems at St. Petersburg, Florida, and Ephrata, Washington,
to a 90-year old flood system at Cheyenne, Wyoming.  The
design and operation of municipal and industrial irrigation
systems will be described here.

System Design

Important criteria in design are wastewater quality and
pretreatment, loading rates, drying period, crop selection,
distribution, and provisions for seasonal change.

Wastewater Quality and Pretreatment - For municipal waste-
water >irrigation, pretreatment is generally required by
state regulations.  Irrigation with untreated wastewater
is forbidden in many states, and the quality of wastewater
is often dictated for irrigation of edible crops.  In most
of the cities surveyed, secondary treatment is provided
prior to irrigation.  Minimum pretreatment for industrial
wastewaters has generally consisted of screening to remove
large solids.  This was found to be required for efficient
operation of sprinkler systems.

Loading Rates — As indicated in Section IV, typical liquid
loading rates are 1.5 to 4.0 in./wk.  Liquid loadings should
be based on the consumptive use of the crops irrigated.
Irrigation practiced with wastewater having TDS concentra-
tions above 750 mg/L (especially in the southwest) should

include applying wastewater in excess of crop requirements
to leach the salts out of the root zone.  The determination
of liquid loadings should be made from previous operational
experience, experience with closely similar conditions,
consultation with agricultural experts, or from pilot work.

Nitrogen loading rates should not greatly exceed the nitro-
gen taken up annually by the crop.  For example, Reed canary
grass can take up 226 Ib/acre of nitrogen per year based on
3.65 tons/acre/yr (additional uptake data in Volume II).
Organic loading rates for industrial wastewaters of 150 to
200 Ib BOD/acre/day without adverse effects have been
reported [43].

Resting Period — As a result of a 10-year study at
Pennsylvania State University, a loading cycle of spraying
for 12 hours followed by resting for 6 days has been
established [41].  Hill [19] reported resting periods for
spray systems ranging from 1 to 14 days.  Ridge and furrow
and flooding systems generally result in applications of
3 to 4 inches in a matter of hours.  Resting periods for
these systems have been as long as 6 weeks but are typi-
cally 7 to 14 days.

Crop_SeJLection — As indicated in Section IV, crop selection
can be Abased on several factors.  Pasture grasses and
alfalfa have been popular choices for municipal effluents.
Industries have generally chosen hydrophytic grasses that
take up large quantities of water.  The National Engineering
Handbook of the Soil Conservation Service contains lists
of boron and salt tolerances of various crops [56].

Distribution System — Sprinkler irrigation systems gener-
ally have the most complicated distribution network.  Two
handbooks on sprinkler irrigation are available [40, 58].
Surface irrigation systems consist of open ditches or
buried mains for distributing water to the furrows or
strips.   Such systems have to distribute the water across
only one dimension of the field.

Provisions for Seasonal Change — After the summer crop is
harvested, a winter cover crop should be planted if
possible.  In climatic Zones A and B it may be possible to
double- or triple-crop a piece of ground.

Storage is required where freezing temperatures do not per-
mit winter operation.  When irrigation begins again in the
spring,  the stored volume as well as the daily occurring
flow must be used.

Some industrial systems provide continuous spraying through
freezing weather without adverse effects on the vegetation
[15].  At other systems damages to vegetation from winter
spraying are claimed [42].

Operation and Management

It is vital that management personnel have a working knowl-
edge of farming practices.   Crops have changing needs for
water and nutrients throughout their growth period, and
application frequency must  reflect these changes.

Monitoring of changes in the weather, soil characteristics,
soil water, groundwater, and crops is important to success-
ful long term operation.  Analysis of the results of such
monitoring will indicate any adverse changes.  Management
changes can then be initiated to correct for the environ-
mental impacts.

If the crop is to be harvested, wastewater applications
must be halted to allow drying of the soil, harvesting of
the crop, and, if necessary, planting of another crop.
Industries have tended to shy away from grazing irrigated
lands.  They often mow the  grass but do not harvest it.  At
Beardmore, in Canada, the grass is kept between 2 and
5 inches high for optimum operation.


The design and operation of overland flow systems have been
developed for industrial wastewaters; therefore these sys-
tems will serve as a basis  for most of this discussion.

System Design

The design of an overland flow system entails selection of
a suitable site and land preparation, considerations of
wastewater quality and pretreatment, determination of load-
ing rates, selection of cover crop, and layout of the dis-
tribution and collection system.  Site selection factors
have been discussed in Section IV.

Land Preparation — Uniform slopes between 2 and 6 percent
are preferred with no depressions or gullies.  The surface
must be quite smooth to promote a thin sheet flow.  A slope
length of 175 feet has been found to provide sufficient de-
tention time to achieve effective treatment for the degrad-
able food processing wastewater at Paris, Texas [10],

Wastewater Quality and Pretreatment — Pretreatment require -
ments for overland flow are screening for large solids

removal and probably grease removal.  At Paris, Texas, the
grease concentration in the untreated wastewater is quite
high and must be reduced to minimize buildups in the distri-
bution lines.  At Ada, Oklahoma, municipal wastewater with
comminution as pretreatment has been sprayed successfully
in a pilot operation.

Loading Rates — Liquid loading rates that have been used
successfully in the design of overland flow systems have
ranged from 0.25 to 0.7 in./day.  Nutrient and organic
loadings have not been correlated with treatment efficiency,
de'tention time on the field, or crop type as yet.

Crop Selection — The cover crop is essential to the design
because it serves as a media or habitat for the biota that
are responsible for the oxidation of organic matter.  The
crop also serves to prevent erosion and to take up signifi-
cant quantities of nutrients from the wastewater.
Effective cover crops include Reed canary, tall fescue,
trefoil, and Italian rye grasses.  Italian rye grass is the
dominant species in the "grass filtration" system at
Melbourne, Australia [22].

Distribution and Collection System — Distribution systems
include the same basic components as spray irrigation
systems.  Buried, permanently set systems have been found
to be preferable to portable or above ground aluminum

A network of ditches must be constructed to intercept the
runoff and to channel it to the point of discharge or
storage.  The collection system should be designed to ac-
cept the added flow from rainfall runoff.

Operation and Management

The major tasks involved in operating an overland flow sys-
tem include (1) maintaining the proper application frequency
or hydraulic loading cycle, (2) managing the cover crop, and
(3) monitoring-the system performance.

Hydraulic Loading Cycle^ — Cycling of the wastewater appli-
cation must be programmed to keep the microorganisms on the
soil surface active.  The application period should be con-
trolled so as not to overstress the system and bring about
anaerobic conditions.  The resting period should be long
enough to allow the soil surface layer to reaerate, yet
short enough to keep the microorganisms in an active state.
Experience with existing systems indicates that practical
cycles range from 6 to 8 hours on and 6 to 18 hours off,
depending on the time of the year.

Cover Crop Management — Removal of the crop is necessary
(1)to realize the removal of the nutrients and minerals
that have been taken up by the plants and (2) to realize
any cash value of the crop as hay.  Cutting of the crop is
beneficial from an operating standpoint, because it elimi-
nates the possibility of tall grass interfering with waste-
water distribution.  On the basis of experimental work con-
ducted at Paris, Texas, it is possible to predict the
time of year and stage of growth when hay of the highest
value can be harvested [10, 16].

Monitoring — Monitoring is necessary to maintain loadings
on the system within design limits.  A routine monitoring
program should be established to determine both the applied
and runoff flow rates as well as selected influent and
effluent quality parameters.


This approach encompasses groundwater recharge projects,
municipal effluent recycle to the land, and industrial
wastewater recycle to the land.  All three types have been
demonstrated to be successful; however, high rate recharge
systems involving municipal wastewater will be the focus
of most of this discussion.

System Design

The important elements of design are site selection, waste-
water quality and pretreatment, loading rates, types of
basin surface, and recovery.  Site selection factors have
been discussed in Section IV.

Waste-water Quality and Pretreatment — The major quality
factors Effecting the infiltration capacity of a system are
the concentrations of suspended solids and organic material.
Pretreatment to secondary quality is suggested for municipal
wastewaters to be applied at high rates.  Again, industrial
wastewaters have been screened or settled to prevent sprink-
ler nozzles from clogging.

Loading Rates — Liquid loading rates generally range from
3to 65 in./wk for moderate rate systems and 5 to 10 ft/wk
for high rate systems.  The design rate must be determined
on the basis of pilot work where infiltration and percola-
tion rates are studied for the particular soil over a con-
siderable period of time.  It should be established for the
poorest climatic conditions that can be reasonably expected.
Because the liquid loading rate will undoubtedly change
during the course of operation in response to variations
in climate, wastewater characteristics, or groundwater

levels, an excess capacity should be included in the design.
A reasonable range for excess emergency capacity would be
10 to 25 percent with 20 percent as typical.

Organic loading rates of 150 to 200 Ib/acre/day or 27 to 36
tons BOD/acre/yr have been used successfully for industrial
applications.  For municipal wastewater a loading rate of
30 tons ob BOD/acre/yr has been reported [61] .   These load-
ings should be considered upper limits for design unless
pilot studies show otherwise.

Type of Basin Surface — The surface of an infiltration-
percolation basin should be designed to disperse the
clogging solids [28].  This has been accomplished by grow-
ing vegetation or by adding a layer of graded sand or
gravel to the surface.  At Flushing Meadows, Arizona, the
vegetated basins were successful [47] .  At Whittier
Narrows, California, adding a layer of pea gravel is re-
ported to have increased the infiltration capacity [29].
Selection of the type of basin surface should be based on
comparative pilot studies at the infiltration site.

Recovery — Recovery of renovated water can be an integral
part of the system design, as at Flushing Meadows, Arizona,
and Santee, California [31, 47], or it can be incidental
with the normal withdrawal from the groundwater basin as at
Whittier Narrows and Hemet, California [29, 59].

Designed recovery systems can prevent the spread of reno-
vated wastewater to aquifers outside the system of recharge
basins and recovery wells.  By keeping the renovated waste-
water separated from the natural groundwaters,  contamina-
tion can be prevented, especially with regard to nitrates.
In addition, renovated water recovered in this  manner could
receive additional treatment, such as for nitrogen removal,
or could be used exclusively for purposes best  suited to its
quality, such as irrigation or recreational lakes.

Operation and Management

Important aspects of infiltration-percolation system manage-
ment include (1) hydraulic loading cycles, (2)  basin surface
management, and (3) monitoring.

Hydraulic Loading Cycle — Intermittent operation is re-
quired to maintain design loading rates and the renovative
capacity of the soil.  Experimentation is required to deter-
mine the best loading cycles consistent with the objectives
of the system.

The resting period, which may vary from 1 to 20 days, is
essential to allow atmospheric oxygen to penetrate the soil
and reestablish aerobic conditions.  As the surface dries,
aerobic bacteria become active in organic matter decomposi-
tion and nitrification.  Organic matter decomposition helps
break up the clogging layer, and the microbial nitrifica-
tion will free ammonium adsorption sites on clay and humus
materials.  When inundation begins again the converted
nitrate will be leached with the applied water until an-
aerobic conditions occur and denitrification begins.

Basin Surface Management — Where bare soil or gravel sur-
faces are used, they should be scarified or raked when
soils accumulate.  For vegetated surfaces, careful opera-
tion of the loading cycle is necessary in the spring until
the vegetation is well established.  The surface may be
harrowed on an annual basis to break up any solids buildup.

Monitoring — Monitoring is needed to maintain successful
operation and to avoid conditions, such as nitrate or phos-
phate buildups, leading to significant environmental
degradation.  Flow meters or measuring flumes are necessary
to measure the wastewater application rate.

Sampling of the wastewater applied should be done on a
regular basis for characteristics such as BOD, suspended
solids, nitrogen, phosphorus, TDS, and coliforms.  A com-
plete analysis of minerals, including heavy metals, should
be performed at less frequent intervals.  Groundwater or
percolate water quality should be sampled for the same
types of characteristics.

Monitoring data should be analyzed to define the opera-
tional efficiency of the system.  The results should be re-
corded to maintain an historical record of the conditions
under which the system has operated and to serve as a basis
for system expansion.

                        SECTION VII

                   ENVIRONMENTAL EFFECTS
The performance of a land application system can be meas-
ured in terms of its effects on the terrain ecosystem.  The
effects of land application of wastewater on the climate,
soil, vegetation, groundwater, surface water, and air will
be described in this section.  Public health considerations
are discussed in Section VIII.


Evaluation of the effect of large land application systems
on local climatic conditions is difficult because of the
lack of observations.  However, it is possible to draw cer-
tain conclusions on the basis of observations taken around
reservoirs both before and after their establishment, from
studies in the vicinity of large irrigation enterprises,
from investigations around large evaporative cooling towers
for industry, and on the basis of various theoretical

The cities man has built, the swamps he drains, and the
reservoirs he creates have resulted in modification of the
climatic conditions over rather limited areas (neglecting
air pollution effects).  The reason for this lies mainly in
the relatively small magnitudes of the heat and moisture in-
puts involved in man's activities as compared with those
in nature.

The climatic changes that accompany irrigation enterprises
are relatively local in extent.  Air moving over an irri-
gated tract will rapidly pick up moisture and the air tem-
perature will cool.  Within the first few hundred feet in
all but the most arid region, the air will have essentially
reached equilibrium.  Once the air has left the moist area,
turbulent mixing will, within just a few miles, reduce its
moisture content to its original low value and return the
temperature to its value upwind of the irrigated tract.


Soil is affected greatly by the application of wastewater,
and in many cases the effects are beneficial.  Soil fertil-
ity is increased by the addition of nutrients.  Soil tilth
is increased by the addition of organics , and in some
cases, excess sodium conditions have been corrected.  For
example, at Woodland, California, alkali soil that was
practically impermeable to rain and unacceptable for com-
mercial irrigation purposes, has been partially renovated
by wastewater application.  Although the soil is still alka-
line, wastewater will infiltrate into it at moderate rates.

The effects of sodium on clay soil permeability is dramati-
cally illustrated by the pulping mill wastewater system in
Terre Haute, Indiana, which handles wastewater containing
sodium concentrations in the range of 16 percent of the dry
solids.  The sealing effect of the sodium is so severe that
the fields must be rested several years and treated exten-
sively with gypsum before they can be used again.

Irrigation with wastewater can lead to salt and heavy metal
buildups depending on the soil, constituent concentrations,
and system operation.  Toxic concentrations of copper and
zinc have apparently accumulated in the soil at two sewage
farms in France, but it has taken over a century for them
to develop [63] .  Toxic levels of TDS in the soil can
be remedied by leaching, resulting in increased TDS levels
in the groundwater.


The application of wastewater to crops is very beneficial
because of the natural fertilizers and nutrients in the
liquid.  Virtually all essential plant nutrients are found
in wastewater.  On the basis of measurements made at
Pennsylvania State University [21, 41], it was found that
the crop yield increases when wastewater rather than ordi-
nary water is used for irrigation.  Yields for hay increased
as much as 300 percent, and for corn, 50 percent.

Heavy applications of wastewater can damage and kill vege-
tation, especially trees [26, 42, 53].  High temperature
industrial wastewaters [18] and high organic loadings
(2,000 Ib/acre/day) have also resulted in killing
vegetation [51] .


Pollution of the groundwater by wastewater applied to the
land is a serious environmental effect that must be guarded
against.  As indicated in Table 2 (Section IV), infiltration
percolation will definitely affect groundwater quality,
and irrigation may affect it.  The wastewater constituents
of major concern here are nitrogen, TDS, toxic elements,
and pathogens.

Nitrogen Effects

Nitrogen contained in wastewater applied to the land may be
in any of four forms:  organic, ammonium, nitrate, and
nitrite.  Nitrite nitrogen is easily oxidized to nitrate in
the presence of oxygen so that concentrations above 1.0 mg/L
for nitrite are rare.  Nitrate nitrogen may be applied to
the land when effluents are nitrified.  Generally, however,
organic and ammonium nitrogen are the principal forms
applied to land.

Organic nitrogen, being suspended instead of dissolved, is
filtered out in the soil matrix and mineralized (decomposed)
into ammonium nitrogen.  The ammonium nitrogen, under aero-
bic conditions, is oxidized by bacteria in two steps
(nitrification) to nitrate nitrogen.  Nitrate is not re-
tained in soil and will leach readily with applied water
[52].  Nitrate may be removed by plant uptake or by bac-
terial reduction to nitrogen gas (denitrification).

TDS Effects

The TDS concentration in the groundwater is affected by the
leaching of minerals from the soil.   The U.S. Public Health
Service has recommended maximum level for TDS of 500 mg/L
in public water supplies.  An extreme example of the in-
crease of TDS in groundwater due to irrigation occurred at
Ventura in southern California.  The applied irrigation
water had a TDS concentration of 1,702 mg/L and the  test
wells had concentrations of up to 8,128 mg/L [60].

TDS buildups as a result cf infiltration-percolation are
less severe because only about 10 percent or less of the
applied wastewater evaporates.  Because of the high  liquid
loading rates, the concentration in the applied wastewater
and that in the percolate will soon come to equilibrium.

Industrial dischargers with high TDS wastewaters may be
constrained against using land application.  At Beardmore,
Canada, application of tannery wastewater with a salt con-
centration reaching 3,000.mg/L has resulted in a chloride

increase in adjacent potable water supply wells which
is threatening the existence of the plant [42].

Trace Elements

Trace elements include heavy metals, such as chromium, lead,
or copper, and refractory organics.  Heavy metals may be
fixed in the soil and rendered nontoxic by bacteria under
cometabolism [36].  Chemical precipitates that are formed
can be leached out of the soil if a heavy loading occurs
or if a significant decrease in pH occurs.

Organics that are degradable are easily oxidized in the
soil matrix and refractory organics are usually fixed in
the soil by adsorption.  Some organics such as humic acids
are mobile in the soil.

Bacteria and Viruses

The movement of bacteria and viruses with the percolating
water is not likely to cause a threat to health.  On the
basis of results from numerous studies at existing sites
and in laboratory experiments, it can be concluded that
most bacteria and viruses are removed after passage through
a few feet of soil [6, 14, 17, 23, 24, 25, 29, 64].  At
Santee, California, viruses injected into the percolating
water were completely removed in 200 feet of travel [31].


The effect on surface waters of land application of waste -
water can be in two areas.  First, the discontinuance of
discharge of treated effluent into surface waters could
affect navigation and the flow rates associated with down-
stream uses of the water; in tidal areas, it could also
permit the intrusion of saline waters further upstream
than usual.

Second, irrigation with underdrains and the overland flow
techniques will produce an effluent that could be dis-
charged to surface waters.  In these cases stream discharge
standards apply and the effects of effluent constituents
must be evaluated.  Generally, with overland flow runoff,
the only constituents that may be of concern would be the
phosphorus concentration.  The bacteria and viruses should
not pose a problem.  Overland flow at Melbourne, Australia,
resulted in a 99.5 percent reduction in E. Coli [22],


Concern for effects on the air from land application centers
around the use of sprinklers.  The effects of land applica-
tion on air include generation of aerosols and odor.
Aerosols will be discussed in Section VIII.  Odors are not
produced by spraying but can be spread that way.  Odors are
generally a sign of system overloading, poor management, or
both, provided the wastewater applied has not become septic
or anaerobic.  Once a wastewater becomes anaerobic it is
difficult to spray, aerate, or spread it without producing
some odors.

                       SECTION VIII

The passing of the Federal Water Pollution Control Act
Amendments of 1971 and 1972 has drawn attention to the use
of land application of wastewater.  Stricter laws and regu-
lations by both state and federal agencies on health as-
pects of land application will undoubtedly be passed in the

Public health aspects are related to (1) the pathogenic
bacteria and viruses present in municipal wastewater and
their possible transmission to higher biological forms in-
cluding man, (2) chemicals that can pose dangers to health,
and (3) the propagation of insects that could be vectors
in disease transmission.


There is no uniform pattern to the regulations in the United
States.  In 1968, Coerver [9] indicated that 11 states
had a specific policy toward sewage irrigation, while in
1972 at least 17 states had specific regulations [8].  The
use of untreated sewage or primary effluent on vegetables
grown for human consumption is generally prohibited.  Some
states allow the use of completely treated, oxidized, and
disinfected sewage on fruits and vegetables which are eaten
raw.  Other states ban the use of any sewage effluent for
irrigation of truck crops and vegetables.  Milk cows may
not pasture on sewage irrigated lands in some states, for
fear of typhoid infection transmitted by udder
contamination [54].  Many states are currently revising or
producing new regulations concerning land application of


The survival of pathogenic bacteria and viruses in sprayed
aerosol droplets, on and in the soil, and on vegetation has

received considerable attention.  It is important to real-
ize that any connection between pathogens applied to land
with wastewater and the contraction of disease in animals
or man would require a long and complex path of epidemiolog-
ical events.  Nevertheless, questions have been raised,
concern exists, and precautions should be taken in dealing
with the possible disease transmission.


Aerosols are droplets of liquid that have become airborne.
Aerosols generated in connection with inadequately disin-
fected wastewater may contain bacteria and viruses.
Spraying such wastewater will produce aerosols as will
aeration tanks, trickling filters, and nonsubmerged
outfalls [44].

The travel time and distance of bacteria in air has been
studied in the United States and in Europe.  The study re-
ported by Merz [33] concludes that the bacterial travel is
limited to the distance of travel of the mist from
sprinklers.  Sepp  [54] reported that, in a German study,
the bacteria traveled from 460 feet to 530 feet with a
6.7-mph wind velocity.  It was estimated that the maximum
travel would range from 1,000 feet to 1,300 feet with an
11-mph wind.  Most of the mist and bacteria landed within
half the maximum measured distance.

Studies have been made on the favorable conditions for bac-
teria to live in aerosol particles.  It was found that, as
the relative humidity decreased and air temperature in-
creased, the death rate of the bacteria increased [44].
Sorber [57] indicates that a 50-micron water droplet will
evaporate in 0.31 seconds in air, with 50 percent relative
humidity and a temperature of 22 deg C.  Thus, dessication
is a major factor in bacterial die-off.

Finally, although much remains to be determined in investi-
gating aerosols and their potential infectivity, many
safeguards can be established.  Among these are adequate
disinfection, sprinklers that spray horizontally or down-
ward with low nozzle pressure, and adequate buffer zones.
Buffer zones may range from 50 feet to 1/4 mile around a
site [54] .  Low trajectory nozzles and screens of trees and
shrubs can be used to limit aerosol travel.  The travel-
ing rig sprinklers designed for Muskegon, Michigan, have
been modified to direct the spray trajectory downward.
Studies of aerosol drift are being planned for the Muskegon
operation  [57].

Survival in Soil and on Vegetation

The survival of pathogenic organisms in the soil can vary
from days to months depending on the soil moisture, soil
temperature, and type of organism.  Sepp [54]  and Dunlop
[13] have prepared extensive tabulations of survival times
of various organisms in soil, in water, and on vegetation.
In relation to survival of coliform organisms, some bacteria
do survive for a longer time in soil.  The survival of
viruses in soil is essentially unexplored [57].  In gen-
eral, bacteria die more rapidly on vegetation than in soil.


Chemicals such as nitrates and TDS can present health haz-
ards if they are present in high concentrations in ground-
water that is used as a water supply.  Because nitrate has
been demonstrated to be the causative agent of methemoglo-
binemia in children, its concentration in drinking water is
limited by the U.S. Public Health Service Drinking Water
Standards to 10 mg/L as nitrate nitrogen.  TDS limits in
drinking water are recommended to be 750 mg/L because high
values of TDS can be harmful to people with cardiac, viral,
or circulatory diseases [57].


Propagation of mosquitoes and flies poses a health hazard
as well as a nuisance condition.  Mosquitoes are known
vectors of several diseases [57] .  In the Pennsylvania
State study, mosquitoes increased in population mainly be-
cause of the wetter environment and the availability of
standing puddles for breeding [41].

At several California industrial land application sites the
major adverse environmental effect has been the propagation
of mosquitoes.  At Hunt-Wesson, Davis, California, the prob-
lem was anticipated, and mosquito fish or gambusia were
planted in the runoff collection sump.  Where vegetation is
grown ample drying should be scheduled in the operation to
prevent massive mosquito propagation.

                        SECTION IX

                      COST EVALUATION
Cost evaluations for irrigation, overland flow, and
infiltration-percolation will be discussed in this
section.  Costs of existing systems will be reported, and
typical costs will be presented for a hypothetical 1-mgd
system operating under each of the three approaches.


Costs reported in the literature are scarce and are given
in various units.  Capital costs will be presented, as
often as possible, in dollars per mgd or dollars per acre.
Where amortization of capital costs is possible, the re-
sults will be given in cents per thousand gallons of treated
wastewater.  Operating and maintenance costs will be given
in cents per thousand gallons of treated wastewater when-
ever possible.


Capital costs for irrigation include those for land, pre-
treatment, transmission, and distribution.  Operating and
maintenance costs are for labor, maintenance, and power.
There are direct economic benefits from irrigation that can
offset some of the operating costs.

Land costs vary tremendously but APWA found that a typical
price in 1972 was $500 per acre.  Pretreatment costs for a
1-mgd system range from 2.7<£/l,OOQ gal. for screening to
              Table  7.   Reported Capital  and
           Operating Costs  for  Spray  Irrigation
Ephrata ,
St. Charles,
Way land,

Flow, Area,
ragd acres
0.80 IS. 6
0.44 55
1.0 129

0.15 30.6
0.50 50
0.5 53
Capital cost, Operating
$/acre $/gpd <£/l,000 gal. Reference
5,100 11.5 -- 64
3,700 47.0 6.8
2,700 -- -- 1, 39

2,090 41.8 -- 64
1,900 19.0 8.7
1,890 20.0 -- 64
Niguel Water

Idaho Supreme   1968
Potato Co. ,
Firth, Idaho

Portales ,       1968
New Mexico

Calabasas,      1965
0.63    80

1.0    120

,3.0    420
a. Capital improvements made from initial year to 1972.

b. Based  on 1972 budget.

range from $5,100 per acre for a solid set system to $140
per acre for a center pivot rig.  Solid set systems are
most common for municipalities, and the remaining systems
that are listed in Table 7 are predominantly solid set.
Capital cost components for spray irrigation include pump-
ing, transmission lines, and distribution network.  In some
cases earthwork, such as leveling and cultivation, or
drainage systems are required.

Operating and maintenance costs range from a low of
2.7471,000 gal. as shown in Table 7 to 23.9^/1,000 gal. for
a cannery operating on a seasonal basis.  Cost components
are power, maintenance, and labor.

Ridge and Furrow Irrigation — Ridge and furrow systems re-
quire a uniform slope of 0.2 to 0.3 percent, and thus earth-
work may be a major cost item.  In rolling terrain, such as
in western Wisconsin, the cost is high because of earthwork,
as shown in Table 8.  On the other hand, in the relatively
flat land near Bakersfield, California, the costs are much
less.  At the Mount Vernon Sanitary District, the cost was
$75 per acre which included leveling, furrow preparation,
and fertilizing [32].

Operating and maintenance costs are dependent upon the
amount of maintenance required.  If frequent cultivation
and maintenance of furrows is required, the costs will be
higher than for spray systems.

Flood Irrigation — Capital costs for flood irrigation, pro-
vided the land is relatively level, are less than for spray
or ridge and furrow systems, as shown in Table 9.  As with
ridge and furrow irrigation, the entire transmission and
distribution system can be by gravity.  Maintenance for
flood systems is generally less than for ridge and furrow,
and this is reflected in the lower operating costs in
Table 9.

Economic Benefits — Cities such as Woodland, California,
Abilene, Texas, Pomona, California, and San Angelo, Texas,
derive direct benefits in different ways.  At Woodland, the
city's land is leased for $23 per acre for summer irriga-
tion, and in addition, a duck club pays about $6 per acre
for the same land for late fall duck hunting privileges.
At Abilene, city land is leased for $12 per acre, and addi-
tional effluent is provided to adjacent farms in place of
cash payments as a result of a lawsuit settlement.  Pomona
purchases treated wastewater from the Los Angeles County
Sanitation Districts at $7 per acre-foot and sells it
to various users at $5 to $22 per acre-foot.  At San Angelo,
four city employees operate the 750-acre city farm at a

             Table  8.   Reported Capital  and Operating
              Costs  for Ridge  and Furrow Irrigation
Location started mgd acres $/acre
Wisconsin 1954 -- 3 2,000
Minnesota 1950 -- 2.8 300
Bakerfield, 1912 12.3 2,400
Mount Vernon 1948 -- 1,000 75
District ,
Minnesota 1953
Ontario 1958 0.7
cost,3 Operating
£/gpd if/1,000 gal. Reference


21 4.8


22. 2C 49

12. 7C 49
a.  Capital improvements made from initial year to 1972.

b.  Based on 1972 budget.

c.  Costs for the year started.
                   Table 9.   Reported  Capital and
               Operating Costs for Flood Irrigation
Capital cost ,
Yf? n T* FT nw A Tf^ i . . __ . 	
Location started mgd acres $/acre £/gpd
Abilene, 1920 4.5 1,550
Woodland, 1889 8.7 240
Ely, Nevada 1908 1.5 1,400 -- 11
San Angelo, 1933 5.0 640 -- 4
cost ,
f/1,000 gal.
    a.  Capital improvements  made from initial year to 1972.

    b.  Based  on 1972 budget.

profit of $30 per acre.  The operating costs for 1972 of
$54,000 were offset by an annual return of $76,700.

Overland Flow

An overland flow system is similar to a spray irrigation
system in that sprinklers are used to distribute the water.
The main differences are that the land is sloping, the
water runs off, and the crop is not always harvested.  The
capital and operating costs are evaluated in the following

Capital Costs — Capital cost items include land, pretreat-
ment, transmission, earthwork, distribution, and collection.
Land costs are quite variable; even at the Paris, Texas,
site they varied from $50 to $600 per acre for the 500 acres
purchased [8].  Pretreatment generally consists of
screening.  Transmission generally is by pumping.

Earthwork will vary with the original topography of the
site.  At Paris, Texas, rolling land was regraded at a cost
of $306 per acre for clearing, $108 per acre for grass
cover, and $188 per acre for miscellaneous work.  On the
other hand, complete regrading of flat land to 2.5 percent
slopes at Davis, California, cost $1,500 per acre.

The original distribution system for Paris, Texas, cost
$348 per acre to install [8].  The cost in 1971 for the
piping at the Hunt-Wesson site at Davis, California, was
about $1,250 per acre.

Collection systems for the runoff are normally included
under earthwork.  At Davis, California, the collection
ditches amounted to 10 percent of the earthwork cost or
about $150 per acre.

Operation and Maintenance — Data on overland flow facilities
are scarce because of the limited number of overland flow
sites in operation.  At Paris, Texas, the annual operational
cost is 5
infiltration-percolation than for irrigation or overland

Capital Costs — These are costs for land, pretreatment,
earthwork,tFansmission and distribution, and recovery.

At Westby, Wisconsin, basins were constructed in a 5 per-
cent hillside.  Land cost was $750 per acre and earthwork
was $2,500 per acre.  The earthwork cost at Flushing
Meadows, Arizona, was $1,500 per basin or $4,500 per acre.
This was an experimental research effort and costs for the
2 acres are expected to be high.

Buxton  [7] has calculated the cost of transmission and dis-
tribution at Flushing Meadows at $98,000.  The recovery
wells there (600 gpm) are estimated to cost $35 per foot,
or $17,500 for each well.

Operation and Maintenance — Operation and maintenance costs
for infiltration-percolation systems consist of costs for
labor, maintenance, and power.  At Flushing Meadows,
Arizona, the operating cost is 2.4^/1,000 gal. while at
Whittier Narrows, California, it is 2.7
           Table  10.  Comparison  of Capital  and  Operating
          Costs for 1-mgd Spray Irrigation,  Overland  Flow,
                 and Infiltration-Percolation Systems3
Cost item
Liquid loading rate, in./wk
Land used, acres
Land required, acres
Capital costs
Land 8 $SOO/acre
Pumping station
Total capital costs
Capital cost per
purchased acre
Amortized cost
Capital cost, f/1,000 gal.
Operating costs
Total operating costs
Operating cost, £/l,000 gal.
Total cost, f/1,000 gal.
Spray irrigation

$ 62,000

Overland flow

$ 38,500

Infiltration -percolation

$ 2,500

$ 7,500
a.  Estimated for 1973 dollars, ENRCC index 1860 and STPCC  index  192.
b.  20 percent additional land purchased for buffer zones and additional capacity.
c,  15-year life for capital items, excluding land; interest rate  7 percent.

Irrigation with primary effluent has been successful; how-
ever, recent regulations may require secondary quality for
irrigation.  Screening and comminuting may be the minimum
pretreatment required for overland flow, but this requires
full-scale substantiation.  High rate infiltration-
percolation requires secondary quality, although moderate
rates can be maintained successfully with primary effluent.


The land needed for each system was calculated from the
1-mgd flow rate and the liquid loading rate.  Typical load-
ing rates were chosen, and the resultant land area was
increased by 20 percent for buffer zones for spray irriga-
tion and overland flow, or excess capacity for infiltration-
percolation.  A land price of $500 per acre was chosen as


For earthwork costs it was assumed that some land prepara-
tion was required for spray irrigation at $100 per acre.
For overland flow, terracing required major earthwork
(assuming previously level land) at $L,000 per acre.  Also
included were costs for preparation, planting, and
fertilizing.  For infiltration-percolation basins, ten
1/2-acre basins were required at $1,000 per basin.

Pumping Stations

A 1-mgd package pumping station would cost $50,000 for both
the spray irrigation and overland flow cases.  It was as-
sumed that the wastewater could be transmitted to the site
by gravity flow; therefore, no pumping stations for distri-
bution were included for infiltration-percolation.


The hypothetical site was located 1 mile from the treatment
plant or wastewater source.  Transmission was by gravity
flow through a 24-inch pipe, installed at a cost of $25 per
foot.  It should be noted that the same plot of land was
not being considered for each approach.


For spray irrigation the cost per acre in 1973 dollars is
$1,400.  In determining this cost, use was made of a set of
curves developed by Allender [1] presented in Volume II.

For overland flow, the distribution pattern was not square
so a typical cost of $1,000 per acre was chosen.  Similarly,
a cost of $1,000 per acre was assigned for distribution
among the 10 basins for infiltration-percolation.


For overland flow, a series of collection ditches were
required at a cost of approximately 10 percent of the dis-
tribution costs, or $6,000.  For infiltration-percolation,
3 wells for recovery were required.  The wells had a capac-
ity of 600 gpm each and, at 100-foot depths, cost $30,000,
including $15,000 for recovery pumps.

Operation and Maintenance

Labor requirements were based on one man, full-time, for
spray irrigation and overland flow.  A single man three-
fourths of the time was necessary for infiltration-

Maintenance costs were calculated as 10 percent of the
capital costs of pumping stations, distribution, and
collection.  Power costs were variable, but were expected
to be 2
                       SECTION X

1.  Allender, G. C., "The Cost of a Spray Irrigation System
    for the Renovation of Treated Municipal Wastewater,"
    Master's Thesis, The Pennsylvania State University
    (September 1972) .

2.  "Assessment of the Effectiveness and Effects of Land
    Disposal Methodologies of Wastewater Management,"
    Department of the  Army, Corps of Engineers, Wastewater
    Management Report  72-1 (January 1972).

3.  Aulenbach, D. B.,  Glavin, T. P., and Rojas, J.  A. R.,
    "Effectiveness of  a Deep Natural Sand Filter for
    Finishing of a Secondary Treatment Plant Effluent,"
    Presented at the New York Water Pollution Control
    Association Meeting (January 29, 1970).

4.  Bendixen, T. W. , et al., "Ridge and Furrow Liquid Waste
    Disposal in a Northern Latitude," ASCE  San. Engr. Div. ,
    9_4, No. SA-1, pp 147-157 (1968).

5.  Blosser, R. 0., and Owens, E. L., "Irrigation and Land
    Disposal of Pulp Mill Effluents," Water and Sewage
    Works,  III, No. 9, pp 424-432 (1964).

6.  Bouwer, H., "Renovating Secondary Effluent by Ground-
    water Recharge With Infiltration Basins," Presented at
    the Symposium on Recycling Treated Municipal Waste-
    water and Sludge Through Forest and Cropland," The
    Pennsylvania State University, University Park,
    Pennsylvania (August 21-24, 1972).

7.  Buxton, J. L., "Determination of a Cost for Reclaiming
    Sewage  Effluent by Ground Water Recharge in Phoenix,
    Arizona," Master's Thesis, Arizona State University
    (June 1969) .

 8.   Center for the Study of Federalism,  Green Land--Clean
     Streams:  The Beneficial Use of Waste Water Through"
     Land Treatment, Stevens^ R7 M., Temple University,
     Philadelphia, Pennsylvania (1972) .

 9.   Coerver, J. F., "Health Regulations  Concerning Sewage
     Effluent for Irrigation," Proceedings of the Symposium
     on Municipal Sewage Eff_lueiit_for^_IY^igation, Louisiana
     Polytechnic Institution (July 30",  1968) .

10.   C. W. Thornthwaite Associates,  "An Evaluation of Cannery
     Waste Disposal by Overland Flow Spray Irrigation,"
     Publications in Climatology, 22, No.  2 (September 1969).

11.   DeTurk, E. E., "Adaptability of Sewage Sludge as a
     Fertilizer," Sewage Works Journal,  7_, No. 4, pp 597-
     610 (1935).

12.   Duffer, W,, "EPA Supported Research," Presented at  the
     Symposium on Land Disposal of Municipal Effluents and
     Sludges, Rutgers University, New Brunswick, New Jersey
     (March 12-13, 1973).

13.   Dunlop, S. G., "Survival of Pathogens and Related
     Disease Hazards," Proceedings of the  Symposium on
     Municipal Sewage Effluent for Irrigation, Louisiana
     Polytechnic Institution (July 30,  1968).

14.   Eliassen, R., et al., "Studies on the Movement of
     Viruses With Groundwater," Water Quality Control
     Research Laboratory, Stanford University (1967).

15.   Fisk, W. W., "Food Processing Waste Disposal," Water
     and Sewage Works, III,  No. 9, pp 417-420  (1964).

16.   Gilde, L. C., et al., "A Spray Irrigation System for
     Treatment of Cannery Wastes," Jour. WPCF, 4_3, No. 8,
     pp 2011-2025 (1971).

17.   Gotaas, H. B., et al.,  "Annual Report on Investigation
     of Travel of Pollution," Sanitary  Engineering Research
     Project, University of California,  Berkeley (1953).

18.   Guerri, E. A., "Sprayfield Application Handles Spent
     Pulping Liquors Efficiently," Pulp §  Paper, 45, No. 2,
     pp 93-95 (1971).

19.   Hill, R. D., Bendixen,  T. W., and  Robeck, G. C.,
     "Status of Land Treatment for Liquid  Waste--Functional
     Design," Presented at the Water Pollution Control
     Federation Conference,  Bal Harbour, Florida (October
     1964) .

20.   Hutchins,  W.  A., "Sewage Irrigation as  Practiced in
     the Western States," Technical Bulletin No.  675, U.S.
     Dept. of Agriculture (March 1939).

21.   Kardos,  L. T., "Crop Response to Sewage Effluent,"
     Proceedings of the Symposium on Municipal Sewage
     Effluent for Irrigation, Louisiana  Polytechnic Inst i -
     tution (July 30, 1968).

22.   Kirby, C.  F., "Sewage Treatment Farms," Dept.  of Civil
     Engineering,  University  of Melbourne (1971) .

23.   Krone, R.  B., "The Movement of Disease  Producing Organ-
     isms Through Soils,," Proceedings of the Symposium on
     Municipal  Sewage Effluent for Irrigation, Louisiana
     Polytechnic Institution(July 1968).

24.   Krone, R.  B., McGauhey,  P. H., and  Gotaas, H.  B.,
     "Direct  Discharge of Ground Water With  Sewage
     Effluents," ASCE San. Engr. Div. , 83, No. SA-4,  pp
     1-25 (1957).

25.   Krone, R.  B., Orlob, G.  T., and Hodgkinson,  C.,  "Move-
     ment of  Coliform Bacteria Through Porous Media," Sewage
     and Industrial Wastes, 30, No. 1, pp 1-13 (1958).

26.   Larson,  W. C., "Spray Irrigation for the Removal of
     Nutrients  in Sewage Treatment Plant Effluent  as  Prac-
     ticed at Detroit Lakes,  Minnesota," Algae and  Metro-
     politan  Wastes, Transactions of the 1960 Seminar, U.S.
     Dept. of HEW (1960).

27.   "Liquid  Wastes From Canning and Freezing Fruits  and
     Vegetables," National Canners Association, Office of
     Research and Monitoring, Environmental  Protection
     Agency,  Program No. 12060 EDK, pp 61-65, 73-74 (August

28.   McGauhey,  P.  H., and Krone, R. B.,  "Soil Mantle  as a
     Wastewater Treatment System," SERL  Report No.  67-11,
     University of California, Berkeley  (December  1967) .

29.   McMichael, F. C., and McKee, J. E., "Wastewater  Recla-
     mation at  Whittier Narrows," Calif. State Water  Quality
     Control  Board, Publication No. 33 (1966).

30.   Melbourne  and Metropolitan Board of Works, "Waste Into
     Wealth," Melbourne, Australia (1971).

31.  Merrell, J. C., et al. , "The Santee Recreation Project,
     Santee, California, Final Report," FWPCA, U.S. Dept.
     of the Interior, Cincinnati, Ohio (1967).

32.  Merz, R. C., "Continued Study of Waste Water Reclamation
     and Utilization," Calif. State Water Pollution Control
     Board, Publication No.  15, Sacramento, Calif. (1956).

33.  Merz, R. C., "Third Report on the Study of Waste Water
     Reclamation and Utilization," Calif. State Water
     Pollution Control Board, Publication No. 18,
     Sacramento, Calif. (1957).

34.  Metcalf § Eddy, Inc., Wastewater Engineering, McGraw-
     Hill Book Co., New York (1972) .

35.  Metcalf, L., and Eddy,  H. P., American Sewerage
     Practice, Vol. Ill, Disposal of Sewage,3rd Ed.,
     pp 233-251, McGraw-Hill Book Co., New York (1935).

36.  Miller, R. H., "The Soil as a Biological Filter,"
     Presented at the Symposium on Recycling Treated
     Municipal Wastewater and Sludge Through Forest and
     Cropland, Pennsylvania State University, University
     Park, Pennsylvania (August 21-24, 1972).

37.  Mitchell, G. A., "Municipal Sewage Irrigation,"
     Engineering News-Record, 119, pp 63-66 (July 8, 1937).

38.  Mitchell, G. A., "Observations on Sewage Farming in
     Europe," Engineering News-Record, 106 , No. 2, pp 66-69

39.  Nesbitt, J. B., "Cost of Spray Irrigation for Wastewater
     Renovation," Presented at the Symposium on Recycling
     Treated Municipal Wastewater and Sludge Through Forest
     and Cropland, Pennsylvania State University, University
     Park, Pennsylvania (August 21-24, 1972).

40.  Pair, C. H., edit., Sprinkler Irrigation, 3rd Ed.,
     Sprinkler Irrigation Association, Washington, D. C.

41.  Parizek, R. R., et al., "Waste Water Renovation and
     Conservation," Penn State Studies No. 23, University
     Park, Pennsylvania (1967).

42.  Parker, R. P., "Disposal of Tannery Wastes," Proceedings
     of the 22nd Industrial  Waste Conference, Part I, Purdue
     University, Lafayette,  Indiana,  pp 36-43 (1967).

43.  Parsons, W. C., "Spray Irrigation of Wastes From the
     Manufacture of Hardboard," Proceedings of the 22nd
     Industrial Waste Conference,  Purdue University,
     Lafayette, Indiana, pp 602-607 (1967).

44.  Poon, C. P. C., "Viability of Long Storaged Airborne
     Bacterial Aerosols," ASCE San. Engr. Div.,  94,
     No. SA 6, pp 1137-1146 (1968) .

45.  Rafter, G. W., "Sewage Irrigation," USGS Water Supply
     and Irrigation Paper No.  3, U.S.  Dept. of the Interior,
     Washington, D. C.  (1897).

46.  Rafter, G. W., "Sewage Irrigation, Part II," USGS Water
     Supply and Irrigation Paper No. 22, U.S. Dept. of the
     Interior, Washington, D.  C. (1899).

47.  "Renovating Secondary Sewage  by Ground Water Recharge
     With Infiltration Basins," Bouwer, H., Rice, R.  C.,  and
     Escarcega, E. D., U.S. Water  Conservation Laboratory,
     Office of Research and Monitoring, Environmental Pro-
     tection Agency, Project No. 16060 DRV (March 1972).

48.  "Role of Soils and Sediment in Water Pollution Control,'
     Part 1, Bailey, G. W., Southeast  Water Laboratory,
     FWPCA, U.S. Dept. of the  Interior (March 1968).

49.  Schraufnagel, F. H. , "Ridge-and-Furrow Irrigation for
     Industrial Wastes Disposal,"  Jour. WPCF, 34, No. 11,
     pp 1117-1132 (1962).

50.  Schwartz, W. A., and Bendixen, T. W. , "Soil Systems  for
     Liquid Waste Treatment and Disposal:  Environmental
     Factors," Jour. WPCF, 42_, No. 4,  pp 624-630 (1970).

51.  Scott, R. H., "Disposal of High Organic Content  Wastes
     on Land," Jour. WPCF, 3_4_, No. 9,  pp 932-950 (1962).

52.  Sepp, E., "Nitrogen Cycle in  Groundwater,"  Bureau of
     Sanitary Engineering, Calif.  State Dept. of Public
     Health, Berkeley (1970).

53.  Sepp, E., "Survey of Sewage Disposal by Hillside
     Sprays," Bureau of Sanitary Engineering, Calif.  State
     Dept. of Public Health, Berkeley  (March 1965).

54.  Sepp, E., "The Use of Sewage  for  Irrigation--A
     Literature Review," Bureau of Sanitary Engineering,
     Calif. State Dept. of Public  Health (1971).

55.  Smith, R. , "Cost of Conventional and Advanced Treatment
     of Wastewater," Jour. WPCF, 40, No. 9, pp 1546-1574

56.  "Soil-Plant-Water Relationships," Chapter 1 in
     Irrigation, Section 15 of SCS National Engineering
     Handbook, Soil Conservation Service, U.S. Dept. of
     Agriculture (March 1964) .

57.  Sorber, C., "Protection of Public Health," Presented
     at the Symposium on Land Disposal of Municipal
     Effluents and Sludges, Rutgers University, New
     Brunswick, New Jersey (March 12-13, 1973).

58.  "Sprinkler Irrigation," Chapter 11 in Irrigation,
     Section 15 of SCS National Engineering Handbook, Soil
     Conservation Service, U.S. Dept. of Agriculture (July

59.  "Study of Reutilization of Wastewater Recycled Through
     Groundwater," Vol. 1, Boen, D. F., et al. , Eastern
     Municipal Water District,  Office of Research and Moni-
     toring, Environmental Protection Agency, Project 16060
     DDZ (July 1971).

60.  Sullivan, D., "Wastewater for Golf Course Irrigation,"
     Water 5 Sewage Works, 117, No. 5, pp 153-159 (1970).

61.  Thomas, R. E., and Bendixen, T. W., "Degradation of
     Wastewater Organics in Soil," Jour. WPCF, 41, No. 5,
     Part 1, pp 808-813 (1969).

62.  Thomas, R. E., and Harlin, C. C., Jr., "Experiences
     With Land Spreading of Municipal Effluents," Presented
     at the First Annual IFAS Workshop on Land Renovation
     of Waste Water in Florida, Tampa (June 1972).

63.  Thomas, R. E., and Law,  J. P., Jr., "Soil Response to
     Sewage Effluent Irrigation," Proceedings of the
     Symposium on Municipal Sewage Effluent for Irrigation,
     Louisiana Polytechnic Institution (July 30, 1968).

64.  Williams, T. C., "Utilization of Spray Irrigation for
     Wastewater Disposal in Small Residential Developments,"
     Presented at the Symposium on Recycling Treated
     Municipal Wastewater and Sludge Through Forest and
     Cropland, Pennsylvania State University, University
     Park,  Pennsylvania (August 1972).

                        SECTION XI


1.   Pound, C.  E., and Crites,  R.  W.,  "Nationwide  Experi-
     ences in Land Treatment,"  Presented at  the  Symposium
     on Land Disposal of Municipal Effluents and Sludges,
     Rutgers University, New Brunswick,  New  Jersey
     (March 12-13, 1973).

2.   Pound, C.  E., and Crites,  R.  W. ,  "Characteristics  of
     Municipal  Effluents," Presented  at  the  EPA-USDA-
     Universities Workshop, University of Illinois
     (July 9-13, 1973) .

3.   "Land Application of Sewage Effluents and Sludges:
     Selected Abstracts," To be published by EPA (fall

                        SECTION XII

                    CONVERSION FACTORS

Adsorption--A process in which soluble substances are
attracted to and held at the surface of soil particles.

Advanced waste treatment--Additional treatment designed to
reduce concentrations of selected constituents present in
wastewater after secondary treatment.

Alkali soil--A soil with a high degree of alkalinity (pH of
8.5 or higher) or with a high exchangeable sodium content
(15 percent or more of the exchange capacity), or both.

Application rates--The rates at which the liquid is dosed
to the land, usually in in./hr.

Aquifer--A geologic formation or strata that contains water
and transmits it from one point to another in quantities
sufficient to permit economic development.

Border strip method--Application of water over the surface
of^ the son.  Water is applied at the upper end of the long,
relatively narrow strip.

Consumptive use--Synonymous with evapotranspiration.

Contour check method--Surface application by flooding.
Dikes constructed at contour intervals to hold the water.

Conventional wastewater treatment--Reduction of pollutant
concentrations in wastewater by physical, chemical, or
biological means.

Drainability--Ability of the soil system to accept and
transmit water by infiltration and percolation.

Effective precipitation—Precipitation that enters the soil
and is useful for plant growth.

Eyapotranspiration--The unit amount of water used on a
given area in transpiration, building of plant tissue, and
evaporated from adjacent soil, snow, or intercepted precipi-
tation in any specified time.

Field area--Total area of treatment for an overland flow
system including the wetted area and runoff area.

Fixation — A combination of physical and chemical mechanisms
in the soil that act to retain wastewater constituents
within the soil, including adsorption, chemical precipita-
tion, and ion exchange.

Flooding—A method of surface application of water which
includes border strip, contour check, and spreading methods.

Grass filtration — See overland flow.

Groundwater--The body of water that is retained in the sat-
uratedzone which tends to move by hydraulic gradient to
lower levels.

Groundwater table--The free surface elevation of the ground-
water;this level will rise and fall with additions or

Infiltration--The entrance of applied water into the soil
through the soil-water interface.

Infiltration-percolation--An approach to land application
in which large volumes of wastewater are applied to the
land, infiltrate the surface, and percolate through the
soil pores.

Irr^ija^ion--Application of water to the land to meet the
growth^needs of plants.

Land application--The discharge of wastewater onto the soil
for treatment or reuse.

Loading rates--The average amount of liquid or solids
appliecT to the land over a fixed time period taking into
account periodic resting.

Lysimeter—A device for measuring percolation and leaching
losses from a column of soil.  Also a device for collecting
soil water in the field.

Micronutrient--A chemical element necessary in only small
amounts (less than 1 mg/L) for microorganism and plant

Mineralization--The conversion of an element from an or-
ganic form to an inorganic form as a result of microbial

Overland flow--Wastewater treatment by spray-runoff (also
known as "grass filtration") in which wastewater is sprayed
onto gently sloping, relatively impermeable soil which has
been planted to vegetation.  Biological oxidation occurs
as the wastewater flows over the ground and contacts the
biota in the vegetative litter.

Pathogenic organisms --Microorganisms that can transmit

Percolation--The movement of water through the soil pores
once it has passed the soil-water interface.

Phytotoxic--Toxic to plants.

Primary effluent--Wastewater that has been treated by
screening and sedimentation.

Refractory organics--Organic materials not removed in sec-
ondary treatment.

Ridge and furrow method--The surface application of water
to the land through formed furrows; wastewater flows down
the furrows and plants may be grown on the ridges.

Saline soil--A nonalkali soil containing sufficient soluble
salts to impair its productivity.

Secondary treatment--Treatment of wastewater by physical,
chemical,  or biological means such as trickling filters,
activated sludge, or chemical precipitation and filtration.

Sewage farming--Originally involved the transporting of
sewage to rural areas for land disposal.  Later practice
included reusing the water for irrigation and fertilization
of crops.

Soil texture--The relative proportions of the various soil
separates--sand, silt, and clay.

Soil water--That water present in the soil pores in an un-
saturated zone above the groundwater table.

Spraying--Application of water to the land by means of
stationary or moving sprinklers.

Spray-runoff--See overland flow.

Tilth--The physical condition of a soil as related to its
ease of cultivation.

Transpiration--The net quantity of water absorbed through
plant roots and transpired, plus that used directly in
building plant tissue.

Viruses --Submicroscopic biological structures containing
all the information necessary for their own reproduction.

Wetted area--Area within the spray diameter of the



BOD    --biochemical oxygen demand

BOD5   --5-day BOD

bu     --bushel

cm     --centimeter

COD    --chemical oxygen demand

deg C  --degree Centigrade

deg F  --degree Fahrenheit

diam   --diameter

ENRCC  --Engineering News-Record construction cost (index)

fps    --feet per second

ft     --foot

gad    --gallons per acre per day

gal.   --gallon

gpd    --gallons per day

gpm    --gallons per minute

hr     --hour
hp-hr  --horsepower-hour
in.    --inch
kw     --kilowatt
Ib     --pound
m      --meter
max    --maximum
mgd    --million gallons per d ty
mg/L   --milligrams per liter
mi     --mile
min    --minute
ml     --milliliter
mm     --millimeter
mo     --month
mph    --miles per hour
MPN    --most probable number
ppm    --parts per million
psi    --pounds per square inch
SAR    --sodium adsorption ratio
sec    --second
sq ft  --square foot
SS     --suspended solids
STPCC  --sewage treatment plant construction cost  (index)
TDS    --total dissolved solids
wk     --week
yr     --year


million gallons x 3.06 = acre-feet

acre-inch x 27,154 = gallons

mg/L x ft/yr x 2.7 = Ib/acre/yr

                   SECTION XIII

   Table  11.  Land Application Sites  Visited
                  for This Study
   1.   Abilene, Texas
   2.   Moulton-Niguel WD, California
   3.   Portales, New Mexico
   4.   San  Francisco, California
   5.   Woodland, California
   6.   Lake George, New York
   7.   Phoenix, Arizona
   8.   Westby, Wisconsin
   9.   Idaho Supreme Potato Co., Firth, Idaho
  10.   Beardmore § Co., Ltd., Acton, Ontario, Canada
    Table 12.   Sites  Visited Prior  to Study
 1.  Bakersfield, California
 2.  Mount Vernon Sanitary District, California
 3.  Campbell  Soup Company, Chestertown,  Maryland
 4.  Campbell  Soup Company, Napoleon, Ohio
 5.  Campbell  Soup Company, Paris, Texas
 6.  Hunt-Wesson Foods, Inc., Davis, California
 7.  California Canners § Growers, Thornton,  California
 8.  Campbell  Soup Company, Sumter, South Carolina
 9.  Seabrook  Farms Company, Seabrook, New Jersey
10.  Sebastopol, California
11.  Tri/Valley Growers, Stockton, California

         Table  13.   Land Application Facilities,
                 On-Site Visits by APWA
Agency and State
No.   Agency and State
                     A.   MUNICIPAL












City of Casa Grande

Lake Havasu San.
District, Lake Havasu

City of Mesa

City of Prescott

City of Tucson


Las Virgenes
Municipal Water
District, Los

Camarillo San.
District, Caraarillo

City of Colton

City of Dinuba

City of Fontana

City of Fresno

City of Hanford

Valley Sanitation

Rossmoor Sanitation,
Inc.,Laguna Hills

City of Livermore

City of Lodi















Irvine Ranch Water
Dist. , Irvine

City of Oceanside

City of Ontario

City of Pleasanton

City of Santa Maria

City of San Bernardino

Santee County Water
Dist. , San Diego

City of San Clemente

City of San Luis Obispo

City of Ventura


City of Colorado Springs


Walt Disney World

Oskaloosa County Water
and Sewer District
Eglin Air Force Base

City of St.Petersburg

City of Tallahassee


St. Charles Utilities,
Inc. , St. Charles

                  Table 13.   (Continued)
No.  Agency and State
No.  Agency and State

33   Forsgate Sanitation,
     Inc., Cranbury

34   City of Vineland


35 •  City of Alamogordo

36   City of Clovis

37   City of Raton

38   City of Roswell

39   City of Santa Fe
     Silver Road Plant

40   City of Santa Fe
     Airport Road Plant


41   Clark County

42   City of Ely

43   Incline Village

44   City of Las Vegas


45   City of Duncan


46   Unified Sewerage
     Agency, Forest Grove

47   City of Hillsboro
48   City of Milton-Freewater


49   Pennsylvania State U.
     State College-University


50   City of Dumas

51   City of Kingsville

52   City of LaMesa

53   City of Midland

54   City of Monahans

55   City of San Angelo

56   City of Uvalde


57   City of Ephrata

58   Town of Quincy

59   City of Walla Walla


60   City of Cheyenne

61   City of Rawlins


62   Mexico City, dry
     weather flow, treated

63   Mexico City, dry
     weather flow, raw

               Table  13.    (Concluded)
 No.   Name,  City,  and State
No.  Name, City, and State
                         B.   INDUSTRIAL
 li   Green Giant Company        13i
      Buhl, Idaho

 2i   Western Farmers  Assoc.      14i
      Aberdeen,  Idaho
 3i   Celotex Corporation
      Largo,  Indiana
 Si   Chesapeake Foods
      Cordova,  Maryland
     Hunt-Wesson Foods, Inc.
     Bridgeton, New Jersey

     U. S. Gypsum Company
     Pilot Rock, Oregon
15i  Weyerhauser Company
     Springfield, Oregon
 4i   Commercial  Solvents         16i
      Terre Haute,  Indiana
 6i   Celotex Corporation        18i
      L'Anse, Michigan

 7i   Gerber Products Co.
      Fremont, Michigan          19i

 8i   Michigan Milk Producers
      Assoc., Ovid, Michigan

 9i   Simpson Lee Paper Co.
      Vicksburg, Michigan

lOi   Green Giant Company
      Montgomery, Minnesota

Hi   Stokely Van Camp
      Fairmont, Minnesota

12i   H.J.Heinz Company
      Salem, New Jersey
     Pet Milk Company
     Biglerville ,  Pennsylvania
17i  Howes Leather Company
     Frank, West Virginia
     American Stores Dairy
     Company, Fairwater,
     Libby, McNeill § Libby
     Janesville, Wisconsin

                Table  14.   Facilities Visited
                 by APWA, Data Not  Tabulated
Re as on
 1     Barstow,  California

 2     Madera, California

 3     Porterville,  California

 4     Visalia,  California

 5.     Whittier  Narrows,

 6     Yuba City,  California

 7     Nantucket,  Massachusetts

 8     Scituate, Massachusetts

 9     Gallup, New Mexico

10     Hobbs , New  Mexico
                   Irrigate only sewage treatment
                   plant  grounds



                   Flow discharged to ditch
                   All flow used by abutting property





                   Facility abandoned

                   Facility abandoned

    Table 15.   Responses  to Mail Survey by  APWA
Agency and State
          No.    Agency and State













     City of Winslow,
     WW Plant

City of Banning

City of Brentwood

Buellton Comm. Dist.

City of Corning

City of Corcoran

Co. Dept. of
Honor Camps

Cutler Public
Utilities Dist.

City of Dixon

City of Elsinore

Dept.of Parks § Rec.
San Diego

Eastern Mun. Water
Dist., San Jacinto

City of Escalon

Fallbrook Sanitary

City of Greenfield

City of Gridley



















City of Hanford

City of Healdsburg

City of Kerman

City of Kingsburg

City of Leucadia

City of Loyalton

City of Patterson

City of Pinedale

City of Pixley
Pomerado Co.  Water

City of Paso  Robles

City of Reedley

City of Ripon

City of Riverbank

City of Riverside

San Bernardino County
Special Districts Div.

San Juan Bautasta

City of Santa Paula

City of Santa Rosa

City of Soledad

               Table  15.   (Continued)
No.  Agency and State
No.   Agency and State
Strathmore Pub.
Util. Dist.
Terra Bella Sewer
Village of Middlevi
Ottawa County, Co.
Road Commission
     Main. Dist.

39   City of Tipton

40   City of Tulare

41   City of Tuolumne

42   Valley Center Muni'c.
     Water District

43   Waterford Comra.Serv.

44   Westwood Comm. Serv.

45   Wheatland Dept. of
     Public Works

46   City of Woodland


47   City of Scott City

48   City of Sublette


49   Village of Cassopolis

50   City of East Jordan

51   Harbor Springs Area,
     Sewage Disposal Auth.

52   City of Harrison











City of Helena

City of West Yellowstone


City of Grant


City of Winnemucca


City of Lovington


City of Dickinson


Boise City


City of Bend


City of Cotulla

City of Coleman

City of Comanche

City of Dalhart

               Table  15.   (Continued)
No.  Agency and State
Agency and State

67   City of Denver City

68   City of Elsa

69   City of Goldthwaite

70   City of Idalou

71   City of Morton

72   City of Munday
73   City of Rails

74   City of San Sab a

75   City of Seagraves

76   City of Van Horn

77   City of Winters


78   City of Soap Lake
No.  Name, City, and State
No.  Name, City and State
                       B.  INDUSTRY
 1   Beardmore, Div. of
     Can Packers, Acton,
     Ontario, Canada

 2   Simpson Lee Paper Co.
     Redding, California

 3   Joan of Arc Company

 4   Joan of Arc Company

 5   Green Giant Company
     Belvidere, Illinois

 6   Campbell Soup Company
     Saratoga, Indiana

 7   Popejoy Poultry
     Logansport, Indiana

 8   Weston Paper $ Mfg.Co.
     Terre Haute, Indiana

 9   Albany Cheese, Inc.
     Grays on, Kentucky

10   Duffy-Mott Co., Inc.
     Hartford, Michigan
Simpson Lee Paper Co.
Kalamazoo, Michigan

Green Giant Company
Blue Earth, Minnesota

Green Giant Company
Cokato, Minnesota

Green Giant Company
Winsted, Minnesota

Borden Co., Comstock
Foods, Waterloo,
New York

H.P.Cannon § Sons,Inc.
Dunn, North Carolina

The Beckman f, Cast Co.
Mercer, Ohio

Crown Zellerbach
Baltimore, Ohio

Deeds Bros.Dairy, Inc.
Lancaster, Ohio

Libby, McNeill § Libby
Liepsic, Ohio

                  Table  15.   (Concluded)
No.  Name, City, and State
     Fox Lake, Wisconsin
No.  Name, City, and State
24 •
Sharp Canning, Inc.
Rock ford, Ohio
Campbell Soup Co.
Paris , Texas
Tooele City Corp.
Tooele, Utah
Lamb -Wes ton
Div. of Amfac
Connell, Washington
Alto Coop Creamery
Astico, Wisconsin
Cobb Canning Co.
* Cobb , Wisconsin
Frigo Cheese Corp.
Wyocena, Wisconsin
Green Giant Co.
Green Giant Co.
Ripon, Wisconsin
Green Giant Co.
Rosendale , Wisconsin
Hoffman Corners
Coop Creamery
Kendall , Wisconsin
Kansas City Star Co.
Park Falls, Wisconsin
Kimberley Clark
Niagara, Wisconsin
Loyal Canning Co.
Loyal, Wisconsin
Mammoth Spring Canning
Oakfield, Wisconsin
Oconomowoc Canning Co.
     Sun Prairie, Wisconsin
                                    * U. S. GOVERNMENT PRINTING OFFICE : 1973— ft6-3 1 0/83

                    S. j  farm  Org<.  at/o:
       Pound,  C.  E.,  and Crites, R. W.
       Metcalf  §  Eddy,  Inc.
       Palo Alto,  California
                      Typt  jRepc and
 '2. S- isori'. 'Jzgai,
       Environmental Protection Agency report number,
       EPA-660/2-73-006a. August 1973.	
A nationwide  study  was  conducted of the current knowledge  and techniques
of land application of  municipal treatment plant effluents  and industrial
wastewaters.   Selected  sites were visited and extensive  literature reviews
were made  (annotated bibliography will be published  separately).   Informa-
tion and data were  gathered on the many factors involved in system design
and operation for the three major land application approaches:   irrigation
overland flow,  and  infiltration-percolation.  In addition,  evaluations
were made  of  environmental effects, public health considerations,  and
costs — areas  in which limited data are available.  Irrigation is  the most
reliable land application technique with respect to  long term use  and re-
moval of pollutants from the wastewater.  It is sufficiently developed so
that general  design and operational guidelines can be prepared from
current technology.   Overland flow was found to be an effective  technique
for industrial  wastewater treatment.   Further development  is required to
utilize its considerable potential for municipal wastewater treatment. In-
filtration-percolation  is also a feasible method of  land application.
Criteria for  site selection, groundwater control, and management
techniques for high rate systems need further development.
 173. Descriptors
*Irrigation systems,  *Design criteria, *Wastewater treatment,  *Costs,
*Groundwater recharge,  *Public health, *Environmental effects,  *Sewage
treatment, *Industrial  wastes, Climatic zones, Reclaimed water,  Wastewater
disposal, Soil  treatment,  History, Crops, Percolation
 17b. Identifiers
 r<.-. cowRXFit-hid Group  05D,  04B,  02A
                     19.  Security Class.

                      ).  Sf  -ityC  s.
21.  Wo. of
Send To:
          WASHINGTON. D. C. 2O24O