EPA-660/2-73-006b
August 1973
Environmental Protection Technology Series
Wastewater Treatment And Reuse
By Land Application - Volume II
Office of Research and Developmer
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
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
standards.
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.
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EPA-660/2-73-006b
August 1973
WASTEWATER TREATMENT AND REUSE
BY LAND APPLICATION
VOLUME II
By
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
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing.Office,"Washington, D.C. 20402 - Price $2.40
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ABSTRACT
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 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 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.
ii
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CONTENTS
ABSTRACT
1,1ST OF FIGURfiS
LIST OP TABLES
ACKNOWLEDGMENTS
Sections
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
Historical Background 8
Land Application Approaches 11
Methods of Application 16
Wastewater Characteristics 19
Wastewater Renovation Mechanisms 25
IV IRRIGATION WITH MUNICIPAL WASTEWATER 30
System Design 30
Management and Operation 50
Environmental Effects 56
Public Health Considerations 60
Irrigation Abandonment 65
111
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CONTENTS (Continued)
Sections Page
V INFILTRATION-PERCOLATION OF MUNICIPAL
WASTEWATER 69
System Design 69
Management and Operation 81
Environmental Effects 38
Public Health Considerations 90
System Failures 91
VI LAND APPLICATION OF INDUSTRIAL
WASTEWATER , 94
Background 94
Wastewater Quality and Pretreatment
Requirements 95
Treatment by Overland Flow 100
Land Application by Irrigation and
Infiltration-Percolation 109
Environmental Effects 120
VII CLIMATIC CONSTRAINTS ON LAND
APPLICATION 122
Climatic Classification for Land
Application Systems 122
Climatic Zones for Land Application 127
Local Climatic Effects from Operation
of Land Application Systems 132
VIII COST EVALUATION 141
Irrigation 141
Overland Flow 150
Infiltration-Percolation 152
Cost Comparison for Hypothetical
1-mgd Systems 155
IX LAND APPLICATION POTENTIAL 159
Municipal Wastewater 159
Industrial Wastewater 163
X REFERENCES 165
XI PUBLICATIONS 178
XII GLOSSARY OF TERMS, ABBREVIATIONS,
SYMBOLS, AND CONVERSION FACTORS 179
XIII APPENDICES 185
IV
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FIGURES
No. Page
1 Land Application Approaches 12
2 Soil Type Versus Liquid Loading Rates
for Different Approaches 17
3 Basic Methods of Application 18
4 Types of Flood Irrigation .- 20
5 Nitrogen Cycle in Soil 27
6 Proportions of Sand, Silt, and Clay
for Different Soil Textures 33
7 Average Daily Consumptive Use for
Irrigated Corn and Meadow at
Coshocton, Ohio 51
8 Schematic of Sampling Pan Well at
Whittier Narrows, California 86
9 Suction Probe for Soil Water Sampling 87
10 Generalized Climatic Zones for Land
Application 128
11 Temperature Change Over an Irrigated
Tract 136
12 Construction Cost of Sewage
Pumping Stations 145
13 Distribution Pipe Costs for Spray
Irrigation 146
14 Cost for Recovery Wells 154
v
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TABLES
No. Page
1 Historical Data on Sewage Farming 10
2 Municipal Wastewater Characteristics 21
3 Site Selection Factors and Criteria
for Effluent Irrigation 31
4 Loading Rates Versus Soil Type and Crop 41
5 Crop Uptake of Nitrogen 42
6 Existing Nitrogen Loading Rates 43
7 Existing Organic Loading Rates 44
8 Moisture-Extraction Depth and Peak-
Period Consumptive-Use Rate for
Various Crops Grown on Deep, Medium
Textured, Moderately Permeable Soils 46
9 Relative Tolerances of Field and
Forage Crops 48
10 Removal Efficiency at Selected Sites 55
11 Plant Uptake of Selected Elements 55
12 Crop Yields at Various Levels of
Wastewater Application 58
13 Survival Times of Organisms 62
14 Soil Types and Hydraulic Characteristics 72
15 Existing Organic and Liquid Loading
Rates for Infiltration-Percolation 78
16 Existing Hydraulic Loading Cycles 83
VI
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TABLES (Continued)
No. Page
17 Removal Efficiency at Selected
Infiltration-Percolation Sites 88
18 Summary of Distances of Travel of
Pollution in Soil and Groundwater 92
19 Characteristics of Various Industrial
Wastewater Applied to the Land 96
20 Peak Season Loading Rates of Overland
Flow Treatment Systems 103
21 Removal Efficiencies on a Concentration
Basis for Overland Flow Facilities 108
22 Organic and Hydraulic Loading
Rates of Selected Industrial
Wastewater Land Application Sites 112
23 Characteristics of Sumter Plant
Wastewater 119
24 Average Monthly Temperature and
Precipitation Values at Representative
Stations in Each of the Five Climatic Zones 129
25 Dew-Point Temperature, Wind, Weather,
and Evaporation Observations in Fields
Irrigated by Overhead Irrigation Lines 137
26 Typical Costs of Pretreatment
for 1-mgd Plants 143
27 Annual Costs of Operation and Maintenance
for Municipal and Industrial Irrigation
Systems 148
28 Comparison of Capital and Operating Costs
for 1-mgd Spray Irrigation, Overland Flow,
and Infiltration-Percolation Systems 156
29 Comparison of Irrigation, Overland Flow,
and Infiltration-Percolation for
Municipal Wastewater 160
30 Detailed Data on Land Application Sites
Visited for This Study 205
VII
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TABLES (Concluded)
No. Page
31 Wastewater Characteristics of Plant at
Paris, Texas 224
32 Land Application Facilities, On-Site Visits
by APWA 234
33 Facilities Visited by APWA, Data Not
Tabulated ' 237
34 Responses to Mail Survey by APWA 238
Vlll
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ACKNOWLEDGMENTS
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, Richard E. Thomas, Project Officer, and
the support of the project by the Office of Research and
Monitoring, 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.
IX
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SECTION I
CONCLUSIONS
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.
GENERAL
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
successful.
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.
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There is a paucity of quantitative information in the
literature on the removal efficiencies of soil systems
with respect to wastewater constituents.
IRRIGATION
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
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
wastewater.
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
0 Infiltration-percolation is another feasible approach
to land application of municipal or industrial waste-
water, and several high rate systems have shown
success.
Criteria for site selection, groundwater control, and
management techniques for high rate systems need fur-
ther development.
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Infiltration-percolation, when practiced as a land
disposal approach, is less reliable than irrigation
from the standpoint of wastewater renovation and long
term use.
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SECTION II
RECOMMENDATIONS
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.
IMPLEMENTATION OF LAND APPLICATION PROJECTS
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, in-
cluding public relations, should be developed to accom-
pany any planning activities for wastewater management,
DEVELOPMENT OF STANDARD PRACTICES
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.
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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.
RESEARCH NEEDS
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.
Irrigation
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
effects.
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.
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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 between BOD loading and treatment effi-
ciency should be investigated for various climates,
lengths of runoff travel, types of grasses, and field
slopes.
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
investigated.
The removal of phosphorus as affected by loading
cycles, length of runoff travel, and type of grass
should be investigated.
Infiltration-Percolation
Operating procedures and conditions that are necessary
for optimum nitrogen removal should be identified and
documented.
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.
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Environmental effects, such as increased leaching of
inorganic compounds and increased ground-water 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.
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SECTION III
INTRODUCTION
Current knowledge on land application of municipal and
industrial wastewater has been gathered and is reported in
two volumes. The purpose of this volume (Volume II) is to
present detailed information on the engineering and design
aspects of land application. It is intended as a compendium
of current knowledge--not as a statement of design guidelines
The study was conducted by reviewing the literature, visit-
ing selected sites (as detailed in Appendix A), and cooper-
ating with the fact-finding effort performed by the American
Public Works Association (APWA).
Separate sections are included on irrigation with municipal
wastewater, infiltration-percolation of municipal wastewater,
land application of industrial wastewater, climatic con-
straints on land application, cost evaluation, and land
application potential. Specifically omitted from the study
is the subject of land application of municipal or indus-
trial waste sludge.
A condensed Summary Report, printed separately as Volume I,
is intended to highlight the state-of-the-art for planners
and managers. References cited by bracketed numbers in the
text are listed in alphabetical order in Section X.
In this introductory section the stage is set for further
discussions by presenting the history of and approaches to
land application, the application techniques, important
characteristics of wastewaters, and renovation mechanisms
in the soil matrix.
HISTORICAL BACKGROUND
Land application of sewage effluents began long before the
complex technology of today's treatment systems was
developed. The simplest and most logical disposal method
for man was to put his sewage in the ground by burying it
in trenches or pits.
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With the recent concern for zero discharge of pollutants,
land application of wastewater is being examined again.
An investigation of systems operated in the past as well
as those continuing to the present may offer insights on
land application.
European Practice
Wastewater application to the land was practiced in Athens
in the B.C. period [80]. Use of effluent for a beneficial
purpose was reported in the sixteenth century in Germany
[25] . The application of municipal wastes was used there
for irrigation purposes on farmland. From that beginning,
through the nineteenth century, the application of sewage
effluents to farmland was practiced in continental Europe
and England. The use of sewage effluent for irrigation
was the simplest method of treatment and disposal available
at that time. The benefits from the natural fertilizers
were also recognized. The early sewage farms were fairly
successful in their operation, provided the management
was competent. When farms were poorly managed, crops
failed, odors were present, and complaints were numerous.
Some of the better farms are listed in Table 1; not many
records are available on poorly operated farms. It is
assumed that they failed and were abandoned.
The crops grown on the sewage farms were usually grains,
grasses, root vegetables, and corn. Some farmers used the
effluent on fields planted with all types of fruits and
vegetables with success. The yield from a sewage farm
would commonly be at least twice that of a conventional
farm in the same area.
Most of the farms had underdrains that conveyed the excess
water to nearby streams. The purity of the stream was
apparently not affected by the added water, illustrating
the treatment given the water by its passage through soil.
The practice of sewage farming spread to South Africa,
Australia, and Mexico as those areas were colonized, and it
continues today.
American Practice
The practice of land disposal of sewage effluents began in
the United States in the late nineteenth century. The
first land disposal projects, also listed in Table 1, were
developed only for irrigation purposes. Groundwater re-
charge projects were not started until the early twentieth
century in the semiarid regions of California and Utah.
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Table 1. Historical Data on Sewage Farming
Date
1559
1861
1864
1863
1S7S
1880
1893
1902
1S23
19:3
1872
1SSO
im
1887
1895
1896
1912
1928
Location
Non-United States
Bun;lau, 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
Pullaan, Illinois'"
Cheyenne, Wyoming
Pasadena, California
San Antonio, Texas
Salt Lake City, Utah
BaKersfield, California
Vineland, New Jersey
Description
Sewage farm
Sewage farm
Sewage farm
Sewage farn
Sewage farm
Sewage farm
Irrigation
Overland flow
Irrigation
Irrigation
Irrigation
Irrigation
Irrigation
Irrigation
Irrigation
Irrigation
Irrigation
Irrigation
Irrigation
Wetted
area,
acres
--
420
152
27,250a
400
1,200
10,376b
3,472b
112,000b
12,600
--
3
40
1.330d
300
4.000a
180
2,400d
14
Flow,
mgd
--
4.5
0-7
ISO2
0.8
22
50b
70b
570b
120
--
0.007
1.85
7.0d
--
20a
4
11.3d
0.8
Average
loading,
in./v.'k
--
2.8
1.2
1.4
0.5
4.7
1 .2
5.2
1.5
2.5
--
0.6
12.0
1.3
--
1.3
S.7
1.2
14.7
Reference
25
81
81
81
96
96
76
76
--
81
21
97
97
--
81
81
97
--
83
a. Data for 1926.
b. Data for 1971.
c. Abandoned around 1900.
d. Data for 1972.
10
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Land disposal sites are not limited to public ownership.
Individual farmers have purchased effluent for crop irriga-
tion on their own land. Sometimes the public agency and
the farmer have combined in a system--the municipality
selling some effluent and the farmer leasing the city's
land and irrigating with the remainder.
Land disposal sites were in existence in 20 states from
Massachusetts to California in 1899 [97]. During the
first half of the twentieth century, land disposal sites
began to predominate in the West as increased land value
and increased population led to abandonment of irrigation
at many sites in the East. The crude sewage farms of the
1890s have been replaced for the most part (1) by managed
farms on which treated wastewater is used for crop produc-
tion, (2) by landscape irrigation sites, and (3) by
groundwater recharge sites.
The results of a survey in 1964 indicated that there were
2,192 land disposal systems in the United States, including
1,278 industrial systems and 914 municipal systems (379
surface applications and 535 subsurface septic tank systems)
[45]. More recently EPA published a 1972 Municipal Waste-
water Facilities Inventory in which 571 surface application
systems were identified. The present total number of in-
dustrial land application systems was not determined in
either this study or the APWA study. The 9 sites visited
during this study and the 196 sites contacted during the
APWA study represent only a portion of the total land appli-
cation systems presently in operation.
LAND APPLICATION APPROACHES
Land application approaches can be classified into three
main groups: irrigation, overland flow or spray-runoff,
and infiltration-percolation. These approaches are illus-
trated on Figure 1.
Irrigation
Irrigation is the controlled discharge of effluent, by
spraying or surface spreading, onto land to support plant
growth. The wastewater is "lost" to plant uptake, to air
by evapotranspiration, and to groundwater by percolation.
Application rates are measured either in inches per day or
week, or in gallons per acre per day. The method of appli-
cation depends upon the soil, the type of crop, the climate,
and the topography. Sloping land is acceptable for irriga-
tion provided that application rates are modified to pre-
vent excessive erosion and runoff.
11
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EVAPORATION
SPRAY OR
SURFACE
APPLICAT ION
ROOT ZONE
SUBSOIL
SPRAY APPLICATION.
SLOPE 2-6?,
ZONE OF AERATION
AMD TREATMENT
KECHAftSE HOUKO
SLOPE
VARI ABLE
DEEP
PERCOLATION
(a) IRRIGATION
EVAPORATION
GRASS AND VEGETATIVE LITTER
SHEET FLOf
,-RUNOFF
/ COLLECTION
(b) OVERLAND FLOW
SPREADING BASIN
SURFACE APPLICATION
PERCOLATION THROUGH
UNSATUfiATED ZONE
MEW tATER TABLE
~rr.... v.. + .\ * .T*-V-....-
^trr*:::::/:: ::::::::::::{:Sj":^*:
ipjpiil
iiiliifiiHiiiil
l:::[Jj[: "*
iiitiitiiiii
i,;.iin...;ti;;i
^;;;;:ii^;K!
iiiiiifs
OLD «ATER TABLE
_7
(c) INFILTRATION-PERCOLATION
FIGURE 1
LAND APPLICATION APPROACHES
12
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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 and suspended solids.
Depending upon the soil type and the crop harvested, re-
movals of nitrogen and phosphorus from the wastewater may
also be quite high.
The use of irrigation as a treatment and disposal technique
has been developed for municipal wastewater and a variety
of industrial wastewaters, including those from the food
processing industry, the pulp and paper industry, tanneries,
animal feedlots, dairies, and some chemical plants. Crops
grown have ranged from vegetables to grasses and cereals.
Overland Flow
Overland flow is the controlled discharge, by spraying or
other means, of effluent onto the land with a large por-
tion of the wastewater appearing as runoff. The rate of
application is measured in inches per week, and the waste -
water travels in a sheet flow down the grade or slope.
Soils suited to overland flow are clays and clay loams with
limited drainability. The land for an overland flow treat-
ment site should have a moderate slope--between 2 and 6
percent [24] . The surface should be evenly graded with
essentially no mounds or depressions. The smooth grading
and ground slope make possible sheet flow of water over the
ground without ponding or stagnation. Grass is usually
planted to provide a habitat for the biota and to prevent
erosion. As the effluent flows down the slope, a portion
infiltrates into the soil, a small amount evaporates, and
the remainder flows to collection channels. As the effluent
flows through the grass, the suspended solids are filtered
out and the organic matter is oxidized by the bacteria
living in the vegetative litter.
The overland flow treatment process has been developed
in this country for treatment of high strength wastewater,
such as that from canneries, with resultant reductions
in BOD from around 800 mg/L down to as low as 2 mg/L [88].
Reductions of suspended solids and nitrogen are also high
although phosphorus reduction is reported to be on the
order of 40 to 60 percent. In Australia overland flow
or grass filtration has been used for municipal waste
treatment for many years, with BOD and suspended solids
removals of about 95 percent. Research is presently being
conducted on the use of the overland flow treatment system
for treatment of raw sewage [124]. No municipal sites
13
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where overland flow treatment is being used in the United
States were encountered in this study. The design and
operation of overland flow systems are discussed in
Section VI.
Infiltration-Percolation
This method of treatment is similar to intermittent sand
.filtration in that application rates are measured in feet
per week or gallons per day per square foot. The major
portion of the wastewater enters the groundwater although
there is some loss to evaporation. The spreading basins
are generally dosed on an intermittent basis to maintain
high infiltration rates. Soils are usually coarse textured
sands, loamy sands, or sandy.loams.
This process has been developed for groundwater recharge of
municipal effluents, municipal wastewater disposal, and in-
dustrial wastewater treatment and disposal. The distinction
between treatment and disposal for this process is quite
fine. Unquestionably, industrial wastewater applied to the
land for the purpose of disposal is also undergoing treat-
ment by infiltration and percolation, whether or not moni-
toring for detection of renovation is being practiced.
Other Disposal Approaches
There are several other approaches to the disposal of waste -
water on land, including subsurface leach fields, injection
wells, and evaporation ponds. Such techniques are generally
limited in their range of application. Leach fields are
prevalent in rural areas and are likely to remain so. The
largest known municipal installation employing leach trenches
is at North Lake Tahoe, California [1], and is only a
temporary design. Details of and criteria for design
of leach fields may be found in the Manual of Septic Tank
Practice [72] . A report by researchers [66] on methods
of preventing failure of leach field systems is suggested
for further study.
Deep well injection of reclaimed wastewater is being prac-
ticed in Orange County, California [138], and has been pro-
posed for Long Island, New York [8, 102]. Because such
practices are, not considered to be wastewater treatment,
they will not be discussed further.
Evaporation ponds also have limited applicability because
of the large land requirements, and climatic constraints.
Although such ponds are designed for disposal, they will
act as stabilization ponds and .limited treatment by micro-
organisms will take place. Where crop irrigation or
14
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groundwater recharge are not permissible because of high
salinity of the wastewater, consideration of evaporation
ponds may be in order.
In the United States as opposed to European nations, there
are no national regulations for the control of land disposal
of effluents. There are federal guidelines for wastewater
treatment, but each state must regulate land disposal
facilities. The aspect of regulation is discussed in
detail in Section IV.
Approach Selection
To make a proper assessment of the type of system or land
application approach that is suitable for a given situation
requires knowledge of many variables. Some of the factors
to be considered are the amount of available land, the need
for reclaimed water, the wastewater characteristics and
flow rates, the type of soil at available sites, and whether
the need is for treatment or disposal. These factors may be
classified as regulatory, economic, and technical.
Regulatory Factors These factors include laws, regulations,
and criteria concerning protection of stream quality, ground-
water quality, and public health. If the available sites
are underlain by aquifers used for potable water supply,
public agencies may not allow infiltration-percolation
systems. With stream standards becoming increasingly strin-
gent, irrigation with underdrains, overland flow, or
infiltration-percolation with recovery may be combined
with other forms of wastewater treatment prior to stream
discharge.
Economic Factors The inclusion of land treatment approaches
with conventional treatment processes depends, in part, on
the economics involved. If wastewater has economic value it
can be reclaimed by land application. The most efficient
approach in terms of percentage recovery would be
infiltration-percolation. If an economic return is impor-
tant, crops grown using overland flow or irrigation can be
sold to recover part of the costs of wastewater treatment.
The costs involved in these three land application approaches
are evaluated in Section VIII.
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 biologi-
cal system, must take into account an annual startup period.
15
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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 design
guideline but rather a general aid in the process of approach
selection.
METHODS OF APPLICATION
There are a number of different ways to apply wastewater to
the land. Each site will have its own physical character-
istics that will influence the choice of the method of
application. The three that are most commonly used are
spraying, ridge and furrow, and flooding. Each of these
methods is illustrated on Figure 3.
Spraying
In the spraying method, effluent is applied above the ground
surface in a way similar to rainfall. The spray is developed
by the flow of effluent under pressure through nozzles or
sprinkler heads. The pressure is supplied by a pump or a
source high enough above the sprinkler heads. By adjusting
the pressure and nozzle aperture size, the rate of discharge
can be varied to any desired rate.
The elements of a spray system are the pump or source of
pressure, a supply main, laterals, risers, and nozzles or
sprinkler heads. Since the system operates under pressure,
there is a wide variety of ground configurations suitable
for this type of disposal. The spray system can be portable
or permanent, moving or stationary.
The cost of a spray system is relatively high because of
pump and piping costs and pump operating costs. The efflu-
ent used in a spray disposal system cannot have solids that
are large enough to plug the nozzles. Sprinkling is the
most efficient method of irrigation with respect to uniform
distribution.
Ridge and Furrow Method
The ridge and furrow method is accomplished by gravity flow
only. The effluent flows in the furrows and seeps into the
ground. Ground that is suitable for this type of operation
must be relatively flat. The ground is groomed into alter-
nating ridges and furrows, the width and depth varying with
the amount of effluent to be disposed and the type of soil.
The rate of infiltration into the ground will control the
16
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CLAY CLAY LOAM SILT LOAM LOAM SANDY LOAM LOAMY SAND SAND
SOIL TYPE
FIGURE 2
SOIL TYPE VERSUS LIQUID LOADING RATES
FOR DIFFERENT LAND APPLICATION APPROACHES
17
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RAIN DROP ACTION
TTTTTTTTTTTTTTTT
(a) SPRINKLER
COMPLETELY FLOODED
\ f
(!i) FLOODING
(O RIDGE AND FURROW
FIGURE 3
BASIC METHODS OF APPLICATION [1151,
!8
-------
amount of effluent used. If crops are to be irrigated with
effluent, the width of the ridge where the crop is planted
will vary with the type of crop. The furrows must be allowed
to dry out after application of sewage effluent so that the
soil pores do not become clogged.
Flooding
The third type of application is flooding. This type can be
accomplished in different ways: border strip, contour check,
or spreading basin. Flooding, as the term implies, is the
inundation of the land with a certain depth of effluent.
The depth is determined by the choice of vegetation and the
type of soil. The land has to be level or nearly level so
that a uniform depth can be maintained. The land does need
"drying out" so that soil clogging does not occur. The type
of crop grown has to be able to withstand the periodic
flooding. The three methods are illustrated on Figure 4.
The border strip method consists of sloped (0.2 to 0.3 per-
cent) strips of land 600 to 1,000 feet long divided by
borders or dikes every 20 to 60 feet [142], The major
difference between this method and the spreading basins is
that this method uses smaller segments of a field and the
ground is sloped.
Contour check is the creation of dikes or levees along the
contour of a hill or slope. The dikes contain the effluent
so it does not run down the slope. The dikes are generally
placed at contour intervals of 0.2 to 0.3 feet.
Spreading basins are shallow ponds which are periodically
flooded with effluent. The basins hold the effluent until
it percolates into the ground, is used by crops, or evapo-
rates into the air. Spreading basins are generally used for
rapid infiltration.
WASTEWATER CHARACTERISTICS
The characteristics of wastewater may be classified as
physical, chemical, and biological. Because industrial
wastewater characteristics are so diverse, even among the
food processing and pulp and paper industries, they are
discussed in Section VI. Municipal wastewater characteris-
tics are listed in Table 2 for (1) untreated wastewater,
(2) a typical secondary effluent, 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 pretreatment by conventional wastewater treatment
processes on characteristics is presented at the end of
this section.
19
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5' 1PE 0. 2-0 3'
BORDERS 1-2 CT HIGH
rf.
n i n M n M 11
i )
(a) BORDER STRIP
LEVEES 2 3 FT HIGH
NATURAL
SLOPE
SLOPE
02 03
(b) CONTOUR CHECK
LEVEES 4-6 FT HIGH
SAND OR GRAVEL
n j n : i J
(c) SPREADING BASIN
FIGURE 4
TYPES OF FLOOD IRRIGATION
20
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Table 2. Municipal Wastewater Characteristics
Constituent
Physical
Total solids
Total suspended
solids
Untreated
sewage
CD
700
200
mg/L fcxc
Typical
secondary
treatment
effluent
(2)
425
25
epi; as noted)
Actual quality
anplied to land
(3)
760-1,200
10-100
Chemical
Total dissolved
solids 500 400 750-1,100
pH, units 7.010.5 7.0±0.5 5.8-8.1
BOD 200 25 10-42
COD 500 70 30-80
Total nitrogen 40 20 10-60
Nitrate-nitrogen 0 -- 0-10
Ammonia-nitrogen 25 -- 1-40
Total phosphorus 10 10 7.9-25
Chlorides 50 45 40-200
Sulfatc -- -- 107-383
Alkalinity (CaCOj) 100 -- 200-700
Boron -- 1.0 0-1.0
Sodium -- 50 190-250
Potassium -- 14 10-40
Calcium -- 24 20-120
Magnesium -- 17 10-50
Sodium adsorption
ratio -- 2.7 4.5-7.9
Biological
Coliform organisms, , ,
MPN/100 ml 10b -- 2.2-10°
Sources:
Column 1 Medium strength [80].
Column 2 - [5] .
Column 3 Range of values obtained from site visits.
21
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Physical Characteristics
The most important physical characteristic of wastewater is
its total solids content. The solids include floating, sus-
pended, colloidal, and dissolved matter.
The solids are important because they have a tendency to
clog the soil pores and coat the land surface. Other phys-
ical characteristics are temperature, color, and odor.
Temperature is not a great problem because municipal waste-
water effluent has a fairly even temperature, 50 deg F to
70 deg F, which is not harmful to soil or vegetation. It
is beneficial in that in winter, it has a thawing effect on
frozen ground and may keep soil bacteria alive. Effluent
has been used to spray on crops in freezing weather to form
an insulating ice coating which protects the crop from cold
air [90].
Color of effluent has little effect on the application to
the crops, but it can be used as an indicator of the compo-
sition of the wastewater. Fresh sewage is usually grey;
septic or stale sewage is black. The presence of industrial
wastes can give the sewage color from chemicals in the waste
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
mercaptons also cause noxious odors. These odors are then
released to the atmosphere by spraying or aerating.
Chemical Characteristic^
The chemical properties of wastewater can be divided into
three categories: organic matter, inorganic matter, and
gases.
The organic matter in wastewater is in the dissolved form
as well as settleable solid form, and it is principally
composed of proteins (40 to 60 percent), carbohydrates
(25 to 50 percent), and fats and oils (10 percent). Other
organic compounds, such as phenols, surfactants, and agri-
cultural pesticides, are generally present in small
quantities. Only when the trace organics reach higher con-
centrations do they become a problem. Ordinarily these
substances are in such a small quantity that they have no
short term effect on the soil or vegetation; however, their
effect on groundwater quality is a point of concern. Long
tern effects of trace organics have not been adequately
determined.
22
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Many of the inorganic compounds provide nutrients for the
vegetation, but they also can be toxic to plants at certain
concentrations. Examples include boron, lead, nickel, and
zinc. The major plant nutrients present in wastewater are
nitrogen, phosphorus, and potassium. The aggregate of dis-
solved compounds is the TDS (total dissolved solids). The
TDS content, often measured as electrical conductivity, is
generally more important than the concentration of a spe-
cific ion such as chloride. TDS values above 750 mg/L for
irrigation waters will require leaching either by adding
excess irrigation water or from rainfall.
The relationship between the principal cations in waste-
water- -calcium, magnesium, sodium, and potassium--is of
importance. When the ratio of sodium to the other cations,
especially calcium and.magnesium, becomes too high, the
sodium tends to replace the calcium and magesium ions on
clay particles. The predominance of sodium ions on clay
particles has the effect of dispersing the soil particles
and decreasing the soil permeability. To determine the
sodium hazard, the SAR (sodium adsorption ratio) has been
developed by the U.S. Department of Agriculture Salinity
Laboratory and is described in detail in Agricultural
Handbook No. 60 [130]. It is defined as follows:
SAR = Na/[l/2 (Ca + Mg)]1/2
where Na, Ca, and Mg are concentrations of the respective
ions in milliequivalents per liter of water.
Gases in wastewater, other than those mentioned in regard
to odors, are relatively unimportant in land application.
Dissolved oxygen is usually depleted soon after wastewater
is applied to the land. Atmospheric oxygen is relied upon
for maintenance of aerobic soil conditions.
Biological Characteristics
Wastewater is teeming with microorganisms that are con-
stantly changing its characteristics. The predominant
microorganisms are bacteria.
Wastewater may contain pathogenic organisms which cause dis-
eases, such as salmonella gastroenteritis, typhoid and
paratyphoid fevers, bacillary and ameobic dysentery, cholera,
and infectious hepatitis [31]. Pretreatment is required to
remove the bulk of these microorganisms from the wastewater.
The presence of enteric pathogens is often ascertained by
testing for coliforms. E. coli (Escherichia coli) are used
23
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as indicator organisms because they are more numerous and
more easily tested for than pathogenic organisms. Tests
have also been developed to distinguish between total coli-
forms, fecal coliforms, and fecal streptococci. These tests
are important because many common soil bacteria are measured
in a total coliform count. It is therefore important that
those bacteria that originate in the digestive tract of man
be isolated to measure the degree of wastewater renovation
in the soil system.
Effects of Pretreatment on Wastewater Characteristics
Conventional wastewater treatment begins with preliminary
operations such as screening and sedimentation. Effluent
from these operations is referred to as primary effluent.
This primary effluent may be further treated by biological
oxidation or by physical-chemical processes. Effluent from
the more widespread biological processes, such as activated
sludge, trickling filters, or oxidation ponds, is referred
to as secondary effluent. Constituents removed by the vari-
ous operations and processes in conventional treatment will
be noted in the following discussion.
Primary Treatment Coarse screens, present in nearly every
treatment plant, remove large floating objects and rags.
Fine screens are generally not used anymore in sewage treat-
ment because the smaller solids are removed by sedimentation
and biological oxidation.
Sedimentation removes much (50 to 65 percent) of the sus-
pended solid matter in the wastewater. Grit and gross
settleable solids are often removed in grit chambers prior
to primary sedimentation. BOD is reduced by primary sedi-
mentation approximately 25 to 40 percent [80] , and some
organic nitrogen, phosphorus, and heavy metals are also
settled out.
Sedimentation will remove most of the Ascaris eggs, but
beef tapeworm eggs, hookworm, amoeba cysts, Salmonella, and
viruses will not be completely removed [111] . Most of the
dissolved and colloidal matter present in wastewater will
not be removed in primary treatment.
Secondary Treatment - Biological oxidation results in the
removal of colloidal and dissolved organics to a large
extent. Additionally, some nitrogen and phosphorus are in-
corporated into bacterial cells and removed by secondary
sedimentation. Most 'dissolved inorganics are not affected
by secondary treatment. Secondary treatment provides an
additional removal of bacteria and viruses by flocculation
and secondary sedimentation.
24
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Disinfection Disinfection, the selective destruction of
disease-causing organisms, may be accomplished using heat,
ozone, bromine, iodine, or, most commonly, chlorine. Ade-
quate disinfection requires complete and rapid mixing and
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 disin-
fection techiques from 106 organisms per 100 ml to less
than 2.2 organisms per 100 ml.
WASTEWATER RENOVATION MECHANISMS
The soil matrix represents a treatment zone where many com-
plex physical, chemical, and biological processes and inter-
actions contribute to the renovation of \vastewater applied
to the land. The major renovation mechanisms include
uptake by plant roots, precipitation, adsorption, oxidation,
ion exchange, and filtration. Although the theory of each
will not be discussed in detail, the mechanisms active in
the removal of important constituents from the wastewater
will be identified. The constituents to be considered are
suspended solids, organic matter, nitrogen, phosphorus,
heavy metals, boron, other dissolved solids, bacteria, and
viruses.
Suspended Solids
Suspended solids in wastewater may be organic (volatile) or
inorganic (fixed). The destruction of volatile solids is
discussed under "Organic Matter." The fixed or inorganic
suspended solids will become incorporated into the soil
through filtration and will not be discussed further.
Organic Matter
The biodegradable organics measured by the BOD can be almost
totally removed by the soil matrix. The mechanism of fil-
tration separates the suspended organics from the wastewater
as it infiltrates the soil, and bacterial oxidation destroys
the trapped particles. This overall removal generally
occurs in the upper 5 to 6 inches of soil [65] and the
major filtration often occurs in the top few centimeters
[126]. Dissolved organics, both biodegradable and resist-
ant, are removed initially by adsorption on clay and humus
material, and subsequently the degradable organics are
oxidized by microorganisms. The degradation process occurs
slowly for resistant compounds, such as pesticides, cellulose,
detergents, and phenols [63]. However, the presence of
high concentrations of phenols and similar organics can
be toxic to microorganisms.
25
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Nitrogen
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. The process of
nitrification is the overall biological oxidation of ammo-
nium to nitrite followed by oxidation of nitrite to nitrate.
Nitrification, mineralization, and denitrification are bio-
logical processes that can occur in soil as shown on
Figure 5.
Generally, organic and ammonium nitrogen are the principal
forms applied to land. Organic nitrogen, being suspended in
stead of dissolved, is filtered out in the soil matrix and
mineralized (decomposed) into ammonium nitrogen. Ammonium
exists in equilibrium with ammonia gas and, at a pH between
7.5 and 8.0, 10 percent of the nitrogen will be in the
gaseous ammonia form [56] . Volatilization of significant
quantities of ammonia requires not only a high pH but also
considerable air-water contact [121], Therefore, the mecha-
nism is not expected to provide significant nitrogen removal
in land application systems.
In the soil the ammonium ion participates in ion exchange
and competes with other actions for exchange sites on or-
ganic and mineral fractions of the soil. However, in the
presence of clay minerals and certain organic soil frac-
tions, ammonium ions are preferentially adsorbed. These
adsorbed ions can be held tightly and may be resistant
to leaching. While in the adsorbed phase, ammonium is
available to some plants for direct uptake and to micro-
organisms for incorporation into cell tissue or for conver-
sion to nitrate under aerobic conditions. Only ammonium
adsorbed in a zone that remains anaerobic is stable [56].
Nitrate nitrogen is not retained in soil by adsorption or
ion exchange, but instead leaches readily with applied
water [109] . The mechanisms for nitrate removal from waste-
water in soil are plant uptake and denitrification.
Denitrification can be a chemical reaction between organic
matter and nitrates, or a biological process in which bac-
teria, under anaerobic conditions in the presence of organic
matter, reduce nitrates to nitrogen gas. The conditions
necessary for significant chemical denitrification do not
normally occur in soil systems used for wastewater
application. Biological denitrification can be promoted by
system management techniques discussed later in the report.
26
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PRECIPITATION
SEWAGE
MINERAL
FERTILIZER
PLANT RESIDUE.
COMPOST
ORGANIC N
NH3
DENITRI-
FICATION
VOLATILIZATION
< DECOMPOSITION^
Jll TRIFICATION_y
NH,
jf
(AnsORPTION) (N.TRIF
ICATION
LEACHING
i__
GROUNDWATER
FIGURE 5
NITROGEN CYCLE IN SOIL [109]
27
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Phosphorus
Phosphorus occurs mostly in the form of orthophosphates
which are removed from solution primarily by the fixation
process described previously for ammonium, and by precipita-
tion as insoluble phosphates [101] . It has been reported
that the amount of phosphorus removal by fixation is less
at pH values betiveen 6 and 7 than for either higher or lower
pH values [101] . Phosphorus can also be removed by plant
uptake and by incorporation into biological solids. These
two mechanisms are important in overland flow systems.
Heavy Metals
Retention of heavy metals in the soil matrix is by adsorp-
tion and ion exchange. Removal of metals from solution by
precipitation occurs to some extent, especially in the
presence of sulfides. Heavy metals are also taken up by
plant and microbial cell synthesis in small amounts. Under
low pH conditions, metals can be leached out of soil
systems. Recent research indicates that up to 300 mg/L of
chromium and zinc can be removed by ion exchange in the
soil [137].
Boron
Boron is an essential plant micronutrient but is toxic to
most plants at 1 to 2 mg/L [67]. Thus, very small quanti-
ties are removed from solution by plant intake. Boron
can be removed in the soil by adsorption and fixation
in the presence of iron and aluminum oxides [100] , but
only to a limited extent [133]. Consequently, it should
be considered that boron not removed by plant uptake will
leach through soil systems.
Oth_er___D_is_sg_lyed__Sol__ids
Potassium, calcium, magnesium, sodium, iron, manganese, and
chlorides are taken up by plants, undergo ion exchange, and*
leach out of soils relatively easily. Potassium is taken
up by crops to the largest extent, while chlorides, bicar-
bonate, and sulfate pass essentially unaffected through the
soil. Depending upon the initial chemical composition of
the soil matrix, the total dissolved solids of the renovated
water may increase, decrease, or remain the same as the
applied wastewater. For instance, infiltration-percolation
through saline soil will result in an increase in TDS in
the percolate until steady state conditions are reached.
In infiltration-percolation systems that are well estab-
lished, there should be little change in TDS in the reno-
vated water as compared to the influent. For irrigation,
28
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however, with considerable evaporation of applied water
taking place, an increase in IDS in the soil \vater is
usually seen.
Bacteria and Viruses
Bacteria are removed by a combination of straining, die-off,
sedimentation, entrapment, and adsorption [53]. Enteric
pathogens may survive in soil for up to 2 months and retain
their virulence during the survival period [65]. In spray-
ing wastewater, some bacteria are intercepted by vegetation
where dessication, die-off, and predators eliminate them.
Predators such as insects and worms are also present in the
soil system. Viruses are removed as effectively as bac-
teria, principally by adsorption [28, 33, 53]. Survival
times of viruses adsorbed in the soil matrix have not been
explored.
29
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SECTION IV
IRRIGATION WITH MUNICIPAL WASTEWATER
Irrigation is the most common form of land application in
the United States with some 367 communities employing
the practice as of 1964 [45] . Of the 571 land application
facilities inventoried by EPA in 1972, 315 were identified
as practicing irrigation. Although it is widespread,
especially in the southwest, there are many complex factors
involved in cropland, forest, or landscape irrigation.
The major factors have been classified as those relating to
(1) system design, (2) management and operation, (3) en-
vironmental effects, and (4) public health considerations.
In an attempt to put these factors into perspective, an
analysis is included on reasons for irrigation abandonment.
Each of these factors will be discussed in the remainder
of this section.
SYSTEM DESIGN
Items that must be considered in an irrigation system de-
sign include the factors important in the selection of the
site, the various techniques of applying the water to the
land, and the design criteria.
Factors iii Site Selection
Factors important in site selection include climate, soil
characteristics and depth, topography, and hydrologic and
geologic conditions. A tabulation of factors and general-
ized criteria for an irrigation site is listed in Table 3.
Climate The macroclimate at a site cannot be changed by
present technology so the different factors of the climate
must be studied with respect to their influence upon the
proposed system. Factors such as temperature range, annual
precipitation, humidity, and wind velocity have a direct
effect on the amount of water that can be disposed of at a
certain location. These factors also have an effect on the
type of crop that can be grown successfully in that area.
30
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Table 3. Site Selection Factors
and Criteria for Effluent Irrigation
Factor
Criterion
Soil type
Soil drainability
Soil depth
Depth to groundwater
Groundwater control
Groundwater movement
Slopes
Underground formations
Isolation
Distance from source
of wastewater
Loamy soils preferable but most
soils from sands to clays are
acceptable.
Well drained soil is preferable.
consult experienced agricultural
advisors.
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
determined.
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.
31
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The consumptive use by plants is in direct relation to the
climate of the area. Consumptive use or evapotranspiration
is the total water used in transpiration, stored in plant
tissue, and evaporated from adjacent soil [11]. The con-
sumptive use varies with the type of crop, humidity, air
temperature, length of growing season, and wind velocity.
The amount of water lost by evapotranspiration can be esti-
mated from the pan evaporation data supplied by the U.S.
Weather Bureau in the vicinity of the site. The amount of
evapotranspiration is equal to a crop factor times the
amount of pan evaporation. The crop factor varies with the
type of crop and the location [115]. Presently available
crop factors have been derived for use under natural mois-
ture conditions or prevalent irrigation practices and may
not be applicable to wastewater irrigation at high rates.
Other methods of estimating evapotranspiration may be
found in references [11, 65, 24],
The length of the growing season affects the amount of
water used by the crop. The length of the growing season
for perennial crops is generally the period beginning v^hen
the maximum temperature stays well above the freezing point
for an extended period of days, and continues throughout
the season despite later freezes [11]. This period is re-
lated to latitude and hours of sunlight as well as the net
flow of energy or radiation into and out of the soil. A
limited growing season will require long periods of storage
or alternate methods of winter disposal.
Soil Characteristics Important soil characteristics in-
clude drainability and balance of certain chemical
constituents. Drainability depends primarily on the mechan-
ical properties of texture and structure. These properties
are largely influenced by the relative percentage of the
three mechanical classes of soil--sand, silt, and clay.
Coarse sand particles range in size from 2.0 mm to 0.25 mm;
fine sand particles, from 0.25 mm to 0.05 mm; silt particles,
from 0.05 mm to 0.005 mm; and particles smaller than 0.005
mm are clay. The relationship among these classes and the
nomenclature of soils is shown on Figure 6.
Clay soils do not drain well. Soils with a relatively high
content of clay are fine textured and often described as
heavy. They retain large percentages of water for long
periods of time. As a result, crop management is difficult
but not impossible. These soils expand or swell with mois-
ture increases, and at such times the soil structure is
susceptible to being destroyed by compaction or cultivation.
When clay soils dry there is often considerable shrinkage
and the ground becomes cracked and very hard.
32
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10
V VV V V
PERCENT SAND
FIGURE 6
PROPORTIONS OF SAND, SILT AND CLAY
FOR DIFFERENT SOIL TEXTURES [115]
33
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On the other hand, sandy soils do not retain moisture very
long, which is important for crops that cannot withstand
prolonged submergence or saturated root zones. An example
of plants harmed by too much water occurred at Detroit
Lakes, Minnesota, where a heavy effluent application
(6 in,/day) resulted in the death of a number of trees
[57]. Soils are considered to be well drained if the in-
filtration rate (entrance velocity of water into soil) is
2 in./day or more as measured in full-scale tests. The
drainability should be determined for a large area (as
will be discussed under loading rates) , not for a localized
test pit.
Drainage also depends upon the absence of lateral and sub-
surface constraints to the flow of water. An example of
lateral constraint would be a sandy soil in a narrow valley
with impermeable clay or rock on all sides. The lateral
transmissibility and percolation rate must be equal to
or higher than the infiltration rate to avoid ponding
and waterlogging of soil.
The balance of chemical constituents in the soil is impor-
tant to plant growth and wastewater renovation. The mecha-
nisms of retention of certain constituents by the soil have
been discussed in Section III under "Wastewater Renovation
Mechanisms." Factors such as salinity, alkalinity, and
nutrient level of the soil should be determined prior
to planting and should be monitored during irrigation
to determine the rate and extent of any buildup. The Soil
Conservation Service has produced extensive soil maps de-
lineating soil physical characteristics to depths of 5 feet
for most parts of the United States.
Some of the indicators of adverse soil conditions are pH,
conductivity, and SAR (sodium adsorption ratio, defined in
Section III) . Most crops grow best in a soil with a neutral
or slightly acid pH. Both highly acid and alkali conditions
can produce sterile soil. Additions of calcium sulfate
(gypsum) will aid alkali soils, and calcium hydroxide
(lime) will aid acid soils. The salinity or TDS of the
soil is commonly measured as electrical conductivity.
In arid regions where annual evaporation is substantially
in excess of annual precipitation, salts will accumulate in
nearly all soils unless leaching is done. According to the
University of California Committee on Irrigation Water
Quality Standards, there is a definite hazard to permea-
bility from using \\rater having an SAR of 8 or more on cer-
tain soils [17] .
34
-------
The adverse factors of high salinity, pH, and SAR may occur
in the same soil producing a saline-alkali soil. Saline
soils are those with conductivities of saturation extracts
greater than 4,000 micromhos/cm. It has been found that
the conductivity of the saturation extract of a soil, in
the absence of salt accumulation from groundwater, usually
ranges from 2 to 10 times as high as the conductivity of
the applied irrigation water [11].
Soil Depth Adequate soil depth is important for root de-
velopment, for retention of wastewater components on soil
particles, and for bacterial action. Roots from plants
can extract \vater from depths ranging from 1 to 9 feet or
more. Retention of wastewater components such as phosphorus,
heavy metals, and viruses is a function of residence time
of wastewater in the soil and the degree of contact between
soil colloids and the wastewater components.
In the soil there are different layers with varying levels
of activity. The activity diminishes when the ground\\'ater
table is reached and the soil is saturated. The different
zones are the surface, root zone, and subsoil.-
The surface of the ground is where the major filtering ac-
tion of the soil occurs. During infiltration the water
passes between the soil particles, and any solids in the
water larger than the soil pores will be filtered out.
Since the soil surface is in contact with the air, a great
amount of aerobic bacterial activity can occur. Large ac-
cumulations of solids will form a coating or slime surface
on the soil and block air and water from passing through.
A drying period will help eliminate the coating. Odors
caused by anaerobic conditions can be present if the slime
coating is not eliminated.
The root area is an area of great activity. Since it is
near the surface, aerobic bacteria are working to break down
the organic substances. The roots are absorbing nutrients
and water. The depth of this activity depends on the type
of plant and type of soil. Plants such as alfalfa can have
roots 9 feet or more into the ground. Generally, this
activity is limited to a depth of about 4 to 5 feet.
The subsoil level is the area between the root zone and the
groundwater table. This is a zone of lessening aerobic bac-
teria activity and is highly variable in depth. The water
content of the soil is generally high, almost to the satu-
rated state.
Groundwater The groundwater table is the level where
free water is present in the soil. The soil is saturated,
35
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and bacteria and dissolved solids can travel freely in
the water between soil particles.
Before a site is selected a great deal about the groundwater
should be known, including depth, variation of depth through
out the site, seasonal variation of depth, direction of
groundwater flow, and groundwater quality. If the ground-
water is far below the surface (> 100 feet), it may take
many months for the applied water to reach it. The applied
water may, however, move laterally and join some adjacent
aquifer or emerge as seepage water. As several levels
of groundwater may underlie the site, the quality and
movement potential of each must be determined unless it is
shown that the lower zones are separated by impervious
strata.
To ensure an aerobic root zone, it is preferred that the
groundwater level ^e maintained at least 5 feet below
the ground surface [106] . The groundwater table can be
controlled in two ways: by installation of an underdrain-
age system, or by pumping from wells near the site. Both
of these methods have been used successfully in practice.
Underdrains have been used in Europe since the 1800s [96,
97].
Topography The topography of the site for cropland irriga-
tion must be such that farm equipment can be used for plant-
ing and harvesting. If the existing topography is not
suitable, the site can be engineered to make it acceptable
for the type of application of wastewater and the type of
crop. The ground slope, if too steep or too uneven, can be
leveled or graded to acceptable limits. Leveling and ter-
racing are the two common methods of changing the slope of
the site.
The different application methods require different ground
slopes. Spray irrigation has been applied to slopes up to
30 percent [110] . Ridge and furrow irrigation has been
accomplished by terracing hillsides [10]. Flooding re-
quires slopes of less than 1 percent.
Native vegetation on the site must be either removed or in-
corporated into the design and operation of the system.
The existing vegetation may aid in the determination of the
types of crops that will be best suited for the site.
Hydrologic and Geologic Conditions Groundwater is the
most important hydrologic and geologic factor and has been
discussed separately. Other important factors are rainfall
and resultant storm runoff, the nature of the hydrologic
36
-------
basin, and the nature of underlying rock formations. Rain-
fall will reduce the capacity of the soil to absorb waste-
water and may require storage or lowering of wastewater
loading rates. Storm runoff must be routed around the site
instead of being allowed to cross the site. If the under-
lying rpck is fractured or crevassed like limestone,
percolating wastewater may short-circuit to the groundwater,
thus receiving less treatment.
Method of Application
The three methods of application--spraying, ridge and fur-
row, and flooding--were described previously. Design
considerations relating to each will be described here.
No irrigation system is completely efficient. Irrigation
efficiency is the percentage of irrigation water that is
made available for consumptive use by crops. Efficiency is
a function of application method and rate, soil type, land
preparation, and management skill. Generally, the water
not consumptively used by plants (and lost to evapotrans-
piration) is lost to deep percolation or surface runoff.
Surface runoff, although a function of management, may
range from 5 percent for porous, open soil to 25 percent
for heavy clay. Deep percolation loss is more a function
of soil type and method of application. For light', porous
soils, deep percolation losses may approach 35 percent,
while for heavy clay they may be as low as 10 percent.
Surface irrigation techniques are generally more suscepti-
ble to losses to deep percolation than spray irrigation
techniques .
Spraying Sprinkler nozzles range in size from 1/16 inch
to 2 inches in diameter. The normal range in wastewater
irrigation is from 1/4 inch to 1 inch. Nozzles are gen-
erally mounted on risers which should be tall enough for
the jet from the sprinkler nozzle to clear the mature plant
foliage. Sprinklers may be low pressure (5 to 30 psi),
intermediate pressure (30 to 60 psi), or high pressure
(above 60 psi) [89] . Low-pressure and intermediate pres-
sure applications may be used on all field crops and soil
types with rates as low as 0.1 in./hr. High-pressure
applications exceeding 1/3 in./hr may result in compaction
of fine textured soil, and may result in injury to crops.
The wind and rate of infiltration of the soil are two major
factors in the design of a sprinkler system. The prevail-
ing wind will blow the spray pattern causing uneven distri-
bution and even dry areas under adverse conditions. A
certain amount of spray overlap is recommended. The lat-
eral spacing should be 65 percent of the spray diameter for
37
-------
no wind and 50 percent for winds with velocities from 5 to
10 mph. High pressure sprays suffer uneven distribution
when wind velocities exceed 4 mph [89].
When wastewater is being sprayed a buffer zone around the
site is recommended. A recently designed system has a
buffer zone of 200 feet around the site [34], while in
Europe requirements for buffer zones have been for as much
as 1/4 mile [111]. Studies have shown that downwind travel
of spray increased 85 feet for every 2.25-mph increase
in wind .velocity [111]. Spraying should cease during
high winds.
Application rates should not exceed the ability of the soil
to absorb the water applied. If the infiltration rate of
the soil is exceeded, ponding will occur which could damage
a crop and possibly lead to odor or mosquito problems. The
size of nozzle, water pressure, and nozzle spacing will be
determined by the application rate. Data on sprinkler
sizing and spacing may be found in references [89, 118].
A new form of spray irrigation that is currently under
study is trickle irrigation. The holes in the distribution
pipe are very small (0.020 inch), and the line pressure is
very low (0.5 psi). With holes so small, the wastewater
could not contain suspended solids to any great extent or
clogging would occur. More study is needed before trickle
irrigation can be used for wastewater disposal.
Ridge and Furrow Ridge and furrow irrigation of crops may
be used where spray irrigation is not preferred because of
high winds, tight soil, or higher cost. This form of irri-
gation needs extensive amounts of land preparation before
the liquid is applied. The land must be relatively flat
and the ridges and furrows must be formed to spread the
water. Uniform distribution of the water is fairly diffi-
cult to maintain with this type of irrigation. Row crops,
such as corn and tomatoes, are grown on the ridges and
wastewater, at a depth of 2 to 6 inches, travels down
the furrows.
Typical ridges are 8 to 10 inches high on 36- to 48-inch
centers, with furrows 10 to 16 inches wide and 6 to 10
inches deep [113]. Furrows may be 150 to 500 feet long.
Flooding Flooding is another type of irrigation that has
been used for crop irrigation, as indicated in Section III.
The site must have a slight slope (0.2 to 0.3 percent) or
be terraced so that uniform distribution can occur. On un-
leveled sloping ground, the process of contour check may be
used. Rice, orchards, and some field grains are irrigated
in this manner.
38
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Alfalfa and grasses used for hay are generally irrigated by
the border strip method of irrigation. Applications of 2
to 4 in./day are typical with resting periods of 5 to
20 days.
Design Criteria
Criteria for design of irrigation systems include (1) waste-
water quality and pretreatment; (2) liquid, nitrogen, and
organic loading rates; (3) land requirements; (4) drying
period; (5) crop requirements; (6) distribution system de-
sign; and (7) flexibility for seasonal or climatic changes.
Wastewater Quality and Pretreatment - Pretreatment of waste-
water to be used for irrigation is needed (1) to protect
the health and hygiene of persons contacting the wastewater
or the crops, (2) to reduce the prevalence of odors, and
(3) to improve operational efficiency and reliability.
The aspect of health and hygiene must be considered when
wastewater is used for irrigation of crops. Wastewater
applied to forage and fiber crops is not required to be
disinfected to a high level in most states. So long as
such crops are irrigated in fields that are posted or
fenced and by surface techniques, no hazard should arise.
This aspect of irrigation will be treated in detail under
"Public Health Considerations."
Since wastewater can become very odorous if it becomes
anaerobic, measures must be taken to prevent this from
occurring. When the wastewater is an effluent from a sec-
ondary treatment plant, the odor problem is not likely to
occur. The treatment processes remove most of the organic
matter that might produce odors in decomposition. If
primary effluent is the irrigation source, then precautions
must be taken so that the soil does not become clogged or
waterlogged and as a result become anaerobic. The best
method of prevention of anaerobic conditions is to allow
the soil to dry between applications. The drying period
allows air to circulate down into the soil and create an
aerobic environment. Another aid is to till or cultivate
the soil, without harming the crops, to help the air circu-
lation and break up any sealing coatings.
If spray irrigation is used, the solids content must be
such that the sprinkler heads do not clog. This means some
sedimentation or screening of the wastewater is desirable
before it is pumped into the system. The diameter of the
nozzle should be more than three times the diameter of the
solids allowed in the irrigation water to prevent clogging.
39
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Liquid Loading Rates The loading rate of wastewater is
affected by conditions of the soil, climate, and crop. The
liquid loading rate must be adjusted to the crop use and
the percolation rate of the soil so that ponding does not
occur. Loading rates and crops for various selected sites
are listed in Table 4. Many municipalities grovv forage
crops because of the health regulations imposed on waste-
water irrigation of edible crops and because the forage
crops are generally easier to grow and market. The exist-
ing loading rates have been classified as high, moderate,
or light so that a general correlation with soil type can
be made.
It should be noted that the higher loading rates of 7 in./wk
and more put those sites into the classification of
infiltration-percolation as they result in annual loadings
of more than 30 feet. A hydraulic application of 2 to 8
ft/yr has been considered the normal range for the classi-
fication of systems under the irrigation approach [124] .
For this report irrigation will encompass hydraulic loading
rates up to 4 in./wk on a seasonal basis with an annual
load of 8 ft/yr. For the systems included in Table 4, the
liquid loading rate is seasonal, not continuous for the
whole year unless otherwise noted.
The determination of the liquid loading rate can be made
from experience with closely similar conditions, consulta-
tion with agricultural experts, or from pilot work. It
should not be made solely on the basis of percolation tests.
Percolation tests are negative tests. Characteristically
they indicate infiltration rates (for a very specific point
on a site) that are excessive and do not reflect the infil-
tration rates that can be expected under managed, full-scale
conditions with a growing crop.
The hydraulic loading capacity will vary with each site;
however, a few examples may be informative. At Lubbock,
Texas, the limit of hydraulic loading for the clay loam
soil without underdrains appears to be 2 in./wk. When this
loading was approached in 1938, 1947, and 1953, additional
land was purchased to reduce the loading rate which is now
about 1.3 in./wk [42]. The hillside sprinkler system at
South Lake Tahoe, California, was abandoned, in part,
because of hydraulic overloading at a rate of 13.4 in./wk.
A loading of about 4 in./wk would seem to be the upper
limit for a true irrigation system.
Nitrogen Loading Rates One of the aspects of wastewater
disposal that needs further investigation is the nitrogen
loading. The soil can eliminate some of the nitrogen,
and the crops can utilize some of the nitrogen, but nitrates
40
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Table 4. Loading Rates Versus Soil Type and Crop
Location
InfiItration-percolation
Eglin AFB, Florida
Quincy, Washington
High irrigation
Han ford, California
Tallahassee, Florida
San Bernardino, California
Hillsboro, Oregon
Moderate irrigation
Abilene, Texas
Alamogordo, New Mexico
Pleasanton, California
Light irrigation
Rawlins, Wyoming
Bakersfield, California
Ely, Nevada
Loading Method
rate, of
in./u'k Soil type application
Crop
11.2a Sand'
Sand
3.7d Sand
2.2C
1.5
1.2
Loam
Gravel
Clay loam
Spraying
7.2 Silty sand Flooding
4.2 Sandy loam Flooding
Spraying
Spraying
3.1 Sandy loam Spraying
3.0 Clay loam Flooding
2.5 Silty clay Flooding
loam
Spraying
Flooding,
spraying
Ridge and
furrow,
f1oodi ng
0.3 Sandy loam Flooding
Forest
Corn, wheat
Corn, oats,
cotton
Corn, mil let,
sorghum, gras?
Grass
Grass, forest
Cotton, maize,
coastal bermuda
grass
Corn, oats,
sorghum, alfalfa
Grass
Alfalfa
Cotton, corn,
barley, alfalfa
Alfalfa
a. Year-round rate.
b. High, 3 to 4 in./wk; moderate, 2 to 3 in./wk; light, <2 in./wk.
41
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can still build up in the groundwater. The acceptable
nitrogen loading rate depends on the type of soil and the
type of crop. Some crops and their annual nitrogen uptake
amounts are listed in Table 5.
To avoid adding excess nitrogen to the soil system, it may
be necessary to limit the nitrogen loading to the amount
that crops can assimilate. This may require a reduction in
the liquid loading rate in some cases. Actual nitrogen
loading rates found in this study in terms of pounds per
acre per year of total nitrogen, and crops grown for differ-
ent sites are listed in Table 6. To determine the nitrogen
loading for St. Petersburg, for example, multiply the total
nitrogen concentration (12 mg/L) by the annual liquid load
(45.9 ft/yr) by a conversion factor of 2.7 for a product
of 1,490 Ib/acre/yr. As seen in this table, nitrogen
loading rates can vary tremendously depending upon the
nitrogen concentration in the effluent and the liquid
loading rates. Comparing the higher loadings with the
probable crop uptake indicates that excess quantities
of nitrogen are being applied. At St. Petersburg the
operation began in 1972 and no buildups have been reported.
At Tallahassee, however, despite the fact that the 4.0
in./wk liquid loading rate is successful, a buildup of
nitrogen over the 7 years of operation has been reported.
Table 5. Crop Uptake of Nitrogen
Nitrogen uptake,
Crop Ib/acre/yr Reference
Alfalfa
Coastal berrauda grass
Corn
Red clover
Reed canary grass
Soybeans
Wheat
155-220
480-600
155
120
226
99-113
62-76
37
95
37
37
24
37
37
42
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Table 6. Existing Nitrogen Loading Rates
Seasonal Annual
liquid liquid Nitrogen
loading rate, load, loading ratef
Location in./wk ft/yr Ib/acre/yr Crop
St. Petersburg, 10.6
Florida
Tallahassee, 4.0
Florida
Golden Gate Park, 1.0
San Francisco,
California
Irvine, California l.S
Oceanside, 1.3
California
Woodland, l.S
California
Calabasas, 1.9
California
Abilene, Texas 3.0
Laguna Hills, 0.3
California
45.9 1,490 Grass
17.3 467 Grass,
millet ,
2.5 337 Grass
corn ,
sorghum
6.5 176 Citrus,
vegetables
5.6 113 Alfalfa
grass
2.5 72 Milo
8.2 67 Alfalfa
2.0 65 Cotton,
bermuda
1.3 18 Grass
, corn,
coastal
, maize
a. Ib/acre/yr = concentration, mg/L x annual liquid load, ft/yr x 2.7.
Source: .APWA and Metcalf 5 Eddy visits.
43
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Organic Loading Rates Organic loadings, if too high, can
clog the soil and seal the surface. Loadings up to 30 tons
of BOD/acre/yr have been satisfactorily applied on an ex-
perimental basis [123]. The periodic "drying out" time will
aid aerobic decomposition of the organic matter and reopen
the soil. The ratio of drying to wetting should be between
3 and 6 to 1.
Some selected organic loading rates in terms of pounds of
BOD per acre per year for sites in operation in the United
States are listed in Table 7. The highest loading is
at Fresno, California, with 15.9 tons of BOD/acre/yr,
and this is the only site listed in Table 7 with an acknowl-
edged odor problem. Two of the cities in Table 7, Fontana,
California, and Forest Grove, Oregon, irrigate successfully
with primary effluent, while the other cities have secondary
treatment or oxidation ponds.
Table 7. Existing Organic Loading Rates
Location
Fresno, California
Mesa, Arizona
Fontana, Californi'a
Forest Grove, Oregon
Santa Maria, California
Colton, California
Cheyenne, Wyoming
Las Vegas, Nevada
Woodland, California
Irvine Ranch, California
Organic loading
rate, a
Ib BOD/acrc/yr
31,800
6,900
6,560
6,080
2,170
1,040
600
450
284
260
Method
of
application
Flooding
Flooding
Ridge and
furrow
Spraying
Spraying
Flooding
Flooding
Spraying
Flooding
Spraying,
ridge and
furrow
Resting
period,
days
--
--
12-18
13
10
--
40
20
12
Crop
Grass
Sorghum, grass
Citrus, hay,
grapes
Grass
Alfalfa
Corn, oats
Alfalfa, grass
Alfalfa
Milo
Citrus,
vegetables
a. Ib/acre/yr - concentration, ng/L x annual liquid load, ft/yr x 2.7.
Source: APWA and Metcalf § Eddy site visits.
44
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Land Requirements Once the controlling loading rate has
been established (usually liquid loading controls) , the
approximate acreage necessary for irrigation can be calcu-
lated knowing the wastewater flow rate. If winter irriga-
gation is practiced, the reduced loading rate in that season
will control the total irrigated acreage requirement. For
emergencies, an alternate area for disposal should be
available. If winter storage is planned, the area must be
designed to receive the. application of both the stored
effluent and the daily occurring effluent the following
year.
For spray irrigation, buffer zones should be included.
Depending on the wind, the degree of isolation of the irri-
gation land, and the degree of disinfection given the
wastewater, buffer zones have been found to vary from a row
of trees and bushes to an open area 200 feet wide.
For surface irrigation, buffer zones are less critical.
At Woodland, California, and Abilene, Texas, for example,
there are no buffer zones, and at Abilene several residences
are within the boundary of the irrigation system.
Drying Period The frequency of application of wastewater
andthe resting or drying out period for a soil will depend
on the evapotranspiration, the amount of rainfall, and the
crop. The application rate for most irrigation sites is
between 1 and 4 in./wk. The hourly rate for spray irriga-
tion is usually 0.16 to 0.40 in./hr. At these rates, the
weekly liquid requirement can generally be applied in 1 or
2 days, and the remainder of the week can be a rest period.
Drying periods may range from 1 to 14 days but are typically
5 to 10 days [45].
The rest period gives the bacteria time to break down the
organic matter, and it gives the water time to percolate
deep into the soil. In this manner, the soil will not be-
come saturated and aerobic conditions will remain. The
time between applications also gives the soil bacteria time
to decompose and mineralize the nitrogen compounds in the
soil. There are systems in which the infiltration rate re-
mains acceptable after 60 years of operation.
Rest times for flooding or ridge and furrow operations
should be longer than for spray irrigation because of the
nature of the loading. The wastewater for these operations
can have more and larger solids than for the spray irriga-
tion method. The higher organic loading requires a longer
treatment time for the soil bacteria. The rest period can
be as long as 6 weeks but is typically 7 to 14 days [133].
45
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Crops The crop selection can be based on various factors:
high water and nutrient uptake, high salt tolerance, high
market value, or low management requirements. A listing of
crops and their peak uptake rate for different areas of the
country is given in Table 8 [115]. The high uptake crops
such as grass, which require little maintenance during the
growing season, represent good selections for cover crops.
Another factor is the need for annual planting. With
perennials, such as grasses, planting has to be done only
once and the crop is established for years. With vegetable
crops, the planting has to be done every year which in-
creases the operational cost. Also, most vegetable crops
require care during the growing period so that a marketable
product is produced.
Table 8. Moisture-Extraction Depth and
Peak-Period Consumptive-Use Rate for Various
Crops Grown on Deep, Medium-Textured, Moderately
Permeable Soils [115]
A
California
(San Joaquin Valley)
Crop
torn
Alfalfa
Pasture
Grain
Sugar beets
Cotton
Potatoes
Depth,
in.
60
72
24
41
72
72
41
Use rate.
In. /day
0.26
.25
.32
.17
.22
.22
.24
B
Texas
(southern
high plains)
Depth,
in.
72
72
72b
72
72
Use rate,
in. /day
0.30
.30.
a
!30b
.15
.25
C
Virginia
(coastal plain)
Depth,
in.
24
36
:o
11
Use rate,
in. /day
0.1!
.22
.22
.11
0
Nebraska
(eastern part)
Depth,
in.
72
96
41
48
48
36
Use rule,
In./iLir
0.2!
.27
.29
.26
.26
.26
L
Wisconsin
(state)
Dv'pth,
in.
24
56
18
18
11
USL- rate,
in./J.iy
0.30
.30.
.:i
.25
.20
Dec idiious
orchards
Citrus orchards
Grapes
Annual legumes
Soybeans
Shallow truck
McJiu» truck
Deep truck
ToMatoes
Tobacco
Rice
96
72
72
.21
.11
J6
.22
60
.27
II
24
II
.16
.11
,17
It
12
18
24
II
.30
.25
.20
.20
.20
.20
a. Cool-season pasture.
b. Kara-season pasture.
46
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Nutrients removed by plants can be divided into two groups,
the essential nutrients and the trace nutrients. The essen-
tial elements, such as nitrogen, phosphorus, and potassium,
are normally found in adequate quantities in municipal
wastewater. The trace elements, such as the heavy metals,
may or may not be present in the wastewater.
Salt tolerance can be an important parameter in crop
selection. A salt buildup in the soil can be toxic to
plants or can stunt their growth and produce a poor crop.
A listing of forage and field crops and their tolerance to
salts and boron is given in Table 9 [130]. Bermuda grass
can tolerate 18,000 micromhos/cm, while ladino clover suf-
fers a SO percent decrease in yield with 2,000 micromhos/cm.
An adequate time for harvesting of crops must be scheduled
into the design of the irrigation system. If farm machinery
is used, the ground must be able to support the vehicles.
California health regulations require a period of 30 days
between the last irrigation with wastewater and harvesting
of many edible crops. The harvesting of grasses requires
drying times after cutting unless silage is being produced.
Distribution System The distribution system for crop irri-
gation consists of four elements: transmission to site,
distribution to outlets, outlet configuration, and controls.
The transmission to the site can be by pressure or by
gravity. The size of the pipe will determine the headless
to the laterals and therefore the pumping head required to
maintain a pressure at the lateral at design flow. The ex-
tra cost of a larger pipe is balanced against the savings
in pumping costs to determine the most economical size.
Velocities in the transmission main should be between 2 and
10 fps. Gravity mains should be at the low end of the
range, and pump mains should be in the middle to upper
range. Where velocities are too high, excessive losses
occur at bends and valves.
The quantity and pressure of the water are the main consid-
erations in choosing the correct pipe material. Other
factors to be considered are permanency of the system,
rigidity, weight (if portable), corrosion, and friction
factor. Where high pressures are involved, the results of
hydraulic analysis for surges and water hammer must be de-
signed into the system to prevent pipe breakage.
Distribution for spraying is through pressure pipes or
laterals that run from the transmission main out into
the field. The laterals are designed to carry the required
47
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Table 9. Relative Tolerances
of Field and Forage Crops [130]
To salt or electrical conductivity'
Tolerant
(partial listing)
Semitolerant
(partial listing}
Sensitive
(complete listing)
Barley
Bermuda grass
Birdsfoot trefoil
Canada wildrye
Cotton
Rape
Rescue grass
Rhodes grass
Sugar beet
Alfafa
Corn (field)
Flax
Oats
Orchard grass
Reed canary grass
Rice
Rye
Sorghum (grain)
Sudan grass
Tall fescue
Alsike clover
Burnet
Field beans
Ladino clover
Meadow foxtail
Red clover
White Dutch clover
To boron
Tolerant
Semitolerant
Sensitive
Sugar beet
Alfalfa
Acala cotton
Pima cotton
Barley
Wheat
Corn
Milo
Oats
Pumpkins
Fruit trees
Grapes
Citrus
a. Tolerant - 10,000-18,000 ymhos/cm;
Semitolerant 4,000-12,000 pmhos/cm;
sensitive - 2,000-4,000 ymhos/cm.
b. Plants are listed in the order of their tolerance.
48
-------
flow of water to the outlets and maintain the necessary
pressure. The pressure variation betiveen the first and
last sprinkler outlet should be less than 20 percent.
The design of laterals is as complex as the design for
transmission mains. At each outlet the flow is reduced by
the outlet discharge and the pressure is also reduced. The
lateral must be designed to maintain the same pressure at
each outlet so that the distribution pattern is uniform. A
lack of uniformity will cause wet spots and dry spots.
The design of laterals should begin at the most distant
lateral and progress backward to the transmission main.
The design flow is added at each outlet, and the friction
losses are computed back to the main.
Some of the factors that affect sprinkler performance are:
nozzle design, pressure, jet angle, sprinkler rotation,
overlap of sprinkler patterns, wind, riser height, and ap-
plication rate. All of these factors have to be considered
when a sprinkler system is designed, and more detailed in-
formation is available [89, 118].
The sprinkler spacing can vary from 20 to 120 feet depend-
ing on the pressure and flow rate. The sprinklers for
permanent systems are usually placed on a square or rectan-
gular pattern. Moving systems have a spacing only along
the lateral, and the movement of the lateral eliminates the
other dimension.
The control of systems can vary from hand operated valves,
such as sluice gates, to electrically or pneumatically oper-
ated types. Most systems use hand operated controls as the
sophistication of remote-controlled equipment is generally
not warranted.
A clock timer may be employed to switch the use of laterals,
and flow measuring devices are also used for more accurate
applications. The usual economy-oriented design is used in
municipal work where man-hours are balanced against equip-
ment costs.
For flooding and ridge and furrow irrigation systems distri-
bution may consist of open ditches, buried pipe with riser
outlets, or gated pipe. A low velocity is preferred to
prevent erosion.
Seasonal Changes
Provisions for seasonal changes must be considered in the
design of a system. If the crop is harvested, a winter
49
-------
cover crop should be planted if possible. Systems cur-
rently in operation, such as the one at Bakersfield,
California, continue through the winter months even though
crop production is low. A year-round crop, such as perma-
nent pasture, is used at Bakersfield to receive most of the
wintertime flow. At sites where freezing is a problem,
continuous operation results in a coating of ice on
everything. This may not adversely affect trees [90], but
it will reduce the degree of wastewater renovation. Annual
rainfall and storm intensities should also be considered in
the design, particularly with regard to confinement of
runoff.
Storage of wastewater is required in areas where the freez-
ing temperatures do not permit winter operation and may be
needed in other areas for periods of harvesting and planting
The storage space must be planned for at the beginning
of operation if no other disposal method is available. In
climatic Zone E (see Figure 10 in Section VII), it is esti-
mated that 3 to 6 months' storage may be required. In
climatic Zone D only 10 to 60 days' storage may be required.
The storage must be great enough to handle the future
as well as present flows. When the operation begins in
the spring, the stored volume must be applied to the land
in addition to the daily occurring flow. Where land is
at a premium, storage may be a limiting parameter.
MANAGEMENT AND OPERATION
The management of an irrigation system is as important as
the site selection and system design. It is vital that
management personnel have a working knowledge of farming
practices as well as principles of wastewater treatment.
Important items in management include seasonal (often
weekly) variation in operation, monitoring to establish re-
moval efficiencies and to forecast buildups of toxic com-
pounds, and ongoing observation of the system to avoid
problems of ponding, runoff, or mechanical breakdowns.
Seasonal Variation in Operation
The operation of a crop irrigation system must adjust to
the changing demands of the crops. Examples of water demand
for corn and alfalfa throughout the growing season are shown
on Figure 7. As shown, the rate of evapotranspiration in-
creases as the plants grow until a peak is reached. The
rate then begins to drop until the crop is harvested. At
this point an alternate plot of land must be irrigated until
harvesting and land preparation are complete and a second
crop is planted. In climates that are warm enough, some
crops can be grown throughout the year. In cooler climates
50
-------
Cu.
CONSUMPTIVE USE FOR YEAR 1953 WITH CORN, FOLLOWED BY WINTER WHEAT
;
CONSUMPTIVE USE FOR YEAR 1955 WITH IRRIGATED
FIRST YEAR MEADOW OF ALFALFA. RED CLOVER. TIMOTHY
FIGURE 7
AVERAGE DAILY CONSUMPTIVE USE FOR IRRIGATED
CORN AND MEADOW AT COSHOCTON, OHIO. [115]
51
-------
\vhere crops will not grow in winter, the wastewater must be
either stored or applied to the bare ground and allowed to
percolate into the ground.
The nutrients available from the wastewater are fairly con-
stant throughout the year; however, crop demands can vary.
A crop such as grass has a fairly uniform nutrient require-
ment during the growing season; however, corn and cotton
need nutrients only at certain times. Since nearly constant
amounts of nutrients are added to the soil, nutrients
can build up and lead to future groundwate'r contamination
when there is little or no crop uptake.
Solids buildup is another potential problem area for site
irrigation. Application of wastewater with high solids
content to the soil in winter when soil bacteria are less
active may lead to a buildup of solids on the surface.
When warmer weather occurs and the ground thaws the greatly
increased microbial activity can result in a temporary
odor problem.
Operational Problems
Problems that have occurred in operating land disposal sites
are of two types: mechanical breakdown, and weather or
climatic. The mechanical problems include pump breakdowns,
sprinkler nozzle plugging, power loss, and piping breaks.
Some piping breaks have been due to freezing of the liquid
in the pipe. Installation of drains will eliminate this
problem if the drains function properly. Other climatic
problems are functions of the eccentricities of nature--a
wet or dry season, hot or cold spells. They must be ex-
pected and dealt with as they occur.
No matter how well designed an irrigation system is it will
not function well without proper management. Even with
automated systems there should be an observer present daily
to ensure a smooth operation. With manual systems, full-
time operators are required. If municipalities are oper-
ating the systems, the operators must be knowledgeable in
agricultural management practices. The need for competent
farm management cannot be overstressed.
Monitoring
Monitoring of the variables involved in the operation of a
wastewate irrigation site should be conducted periodically
to ensure reliable operation. These variables are climate,
soil, soil water, groundwater, and crops.
52
-------
The climatological data are available from the U.S. Weather
Bureau for any area; however, local conditions may vary
from the Weather Bureau data if the measuring station is
very distant from the irrigation site. A local station
measuring rainfall, temperature, and wind data would be
helpful to augment the government data.
On the basis of this study it is concluded that the soil
and soil water should be sampled at least twice a year
to determine needed nutrients or disclose a buildup of
any substance that would be harmful to crop production.
Samples should be taken from several parts and depths of
the site to get a representative sample of the soil
conditions.
The groundwater should be monitored by sample wells through-
out the year. A well should be placed in each possible
direction of groundwater movement [18] . A sampling site
must be established where the groundwater enters the site
so that a comparison can be made or contamination discovered
Samples of the crops should be taken during the growing
season to determine if there are any deficiencies in the
crop uptake. Instruments are available to measure the
moisture deficit of crops in place by electronic means.
Tests for specific elements require the removal of leaves
and stems for laboratory analysis.
Analysis The climatological data should be analyzed to
obtain weather patterns so that the most efficient crop
operation can be established. High amounts of rainfall may
require lower wastewater application rates in order that
the soil does not become waterlogged. Temperature patterns
can be used to determine statistically when killing frost
first occurs and when planting can be done with relative
safety. Also, the length of the growing season can be de-
termined from the data, and the best selection of crop or
combination of crops can be made for that length of time.
Wind patterns will affect spray distribution and, at times,
will prohibit spraying altogether.
On the basis of this study it is suggested that the minimum
parameters to be analyzed should include pH, nitrogen,
potassium, phosphorus, and conductivity of the soil and
soil water. The SAR should be checked annually. Levels
of plant-harming elements, such as boron, should also be
analyzed periodically. The constituents of the wastewater
will indicate which elements to test for to avoid a buildup
of any harmful substances.
53
-------
The groundwater should be monitored and analyzed for bac-
teria, nitrogen, and IDS increases. A comparison between
the groundwater quality above and below the site will
give the best indication of contamination.
The crops need to be analyzed only when a deficiency or
problem appears in the growth. Since the irrigation is
done on a regular schedule, there should be no problem
with low water content.
Reporting At the present time, very few states require a
report of monitoring results. In California, this require-
ment resides with the Regional Water Quality Control Boards.
A report is required if the quantity or quality or the mode
of operation is changed from the originally approved method.
Periodic reporting is required only if the Regional Board
so states at the time the application for a disposal site
is processed and approved.
As the process of land application becomes more widespread,
more regulations will be made to control it and require-
ments for increased reporting of monitoring results will
result. The results of tests discussed in this section
should be the minimum required for reporting.
Treatment Efficiency
The treatment efficiency of a crop irrigation site is the
highest of all the types of land application. The major
reasons are the removal of nutrients by the crop and the
relatively low application rates. The removal of organic
matter will be satisfactory as long as the infiltration
rate is maintained and the soil does not become clogged.
As shown in Table 10, the removal of BOD is 95 percent or
more and the removal of suspended solids under proper
operation should be 97 percent or more.
The nutrient uptake efficiency will vary with the crop
growth. As the crop develops, the use of nutrients will
increase; if the application of nutrients is not as high as
the uptake, the nutrients will be taken up from the soil or
a deficiency will result. A balance must be established
between the amount of nutrients applied or in the soil and
the uptake of the crop. Values of crop uptake for various
elements in pounds per acre are given in Table 11. In
Arizona, crop uptake accounted for 75 percent of the applied
nitrogen, 90 percent of the applied phosphorus, and 60 per-
cent of the applied potassium [112].
Enteric organisms are almost completely removed by the soil
[40, 41, 138] provided that aerobic conditions are
maintained. The removal efficiency for E. Coli is reported
54
-------
Table 10. Removal Efficiency at Selected Sites
Loading Removal efficiency , %
T* 1 t'P - - .
Location in./wk BOD SS N P E. Coli
Lake Tahoe, ,
Cali£orniaa 13.4 -- -- 56 91 96
Cincinnati, Ohio
(sand) 11.2 95 -- 20 30
Cincinnati, Ohioc
(silt loam) 11.2 95 -- 50 96
Cincinnati, Ohioc 11.2 -- -- 85 99
Pennsylvania ,
State University0 4.0 38 99 91 99 99
Melbourne ,
Australia0 1.3 98 97 90 80 98
Reference
36
10
10
106
90
51
a. Data on runoff during 1964; operation ceased in 1968.
b. Removal from chlorinated secondary effluent.
c. Experimental outdoor lysimeters 6 ft deep at Taft Sanitary
Engineering Center.
d. Removals from secondary effluent at 3-ft depth.
e. Removals from raw wastewater at 4- to 6-ft depth.
Table 11. Plant Uptake of Selected Elements [133]
Uptake of elements,
Plant
Alfalfa
Corn
Potatoes
Red clover
Rood canary
grass
Soybeans
Khcat
N
220
155
200
126
226
110
76
P
21
25
16
13
36
18
14
S
16
18
10
9
--
10
11
B
0.6
0.4
--
0.2
9.4
0.1
0.3
K
110
52
220
81
--
48
42
Ca
150
21
52
92
69
26
12
Ib/acre/yr
Xa
3
7
3
4
64
--
1
Mg
15
23
4
22
3.8
16
8
Fe
0.9
1.4
--
1.0
17
0.6
0.7
Mn
0.5
1.4
--
0.6
--
0.2
0.5
Zn Cu
0.3 0.1
0.6 0.1
--
0.3 0.1
-.
0.03
0.2 0.03
55
-------
to be between 98 and 99 percent. Bacteria travel only
a few feet in the unsaturated soil zone [53, 55, 104], but
they can travel a few hundred feet in groundwater flow
[108].
As most irrigation soils are loamy, they have a consider-
able capacity for retention of metals by ion exchange and
adsorption. Most toxic substances are applied in very
small quantities so that the soil can remove them
efficiently. Continuous sampling of both the wastewater
and the soil \\rill alert the operator of the site to any
buildup problems.
ENVIRONMENTAL EFFECTS
Effects on the physical environment from wastewater irriga-
tion include those on the climate, soil, vegetation, ground-
water, and air. Effects on human and animal life are
described under "Public Health Considerations."
Climate
As will be shown in a later section (VII), the effects of
irrigation on the climate are limited to extreme local
conditions. Air passing over the site will pick up mois-
ture and will be cooled or warmed, but within a few hundred
feet downwind from the site, original conditions will exist.
Studies were made on large (1-million acre) lakes in Russia,
and the data collected over 25 years show very localized
effects [132].
Soil
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
or friability 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 percolate into it at moderate rates.
Soils used in irrigation have considerable organic and clay
contents so that retention of phosphorus, fluoride, metals,
nondegradable organics, bacteria, and viruses takes place
to a great extent. Also, irrigation depends upon evapora-
tion for removal of a considerable portion of the applied
wastewater, and this process concentrates the constituents
that remain in the water. As a consequence plant toxicity
56
-------
that is due to buildup of metals and TDS can develop.
Phytotoxic 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 [125].
Phytotoxic levels of TDS can be remedied by leaching (adding
excess irrigation water).
Vegetation
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. Measurements made at Pennsylvania State
University [49, 90] show that the crop yield increases
when wastewater rather than ordinary water is used for
irrigation. Hay yields increased as much as 300 percent,
corn grain increased 50 percent. The increased yields of
crops under varying application rates of municipal waste-
water are given in Table 12.
The nutrients derived from wastewater are-nitrogen, phos-
phorus, potassium, lime, trace elements, and humus.
Nitrates can be utilized by growing plants. By applying
wastewater intermittently, nitrogen will be converted to
the nitrate form and will be fully available to crops dur-
ing the growing season.
Calcium in the form of lime is an indirect fertilizer that
neutralizes acidity and checks some plant diseases. Soils
high in organic matter, such as muck and peat, are gener-
ally deficient in calcium as are clayey soils. Calcium
in sewage exists in the form of carbonate, which is favor-
able to important soil organisms. Trace elements in waste-
water are sulfur, magnesium, iron, iodine, sodium, boron,
manganese, copper, and zinc. These elements can be helpful
in plant development; however, in high concentrations, they
can be toxic.
Toxic elements can be toxic either to the plants or to the
animal that consumes the crop. Analysis of the soil and of
the crop itself will give the levels of concentration of
any toxic elements so that proper crops can be selected.
Certain crops have a higher tolerance for toxic substances
than others. An example is oats and flax with respect to
nickel. Oats have a high tolerance at 100 mg/L, while flax
has a low tolerance at 0.5 mg/L [133].
The uptake of a toxic substance, like lead, into the edible
portions of the plant has been studied to determine soil
concentrations necessary to create toxic conditions.
57
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Table 12. Crop Yields at Various Levels of
Wastewater Application [49]
Crop
1963
Wheat
Corn
Alfalfa
Red clover
1964
Red clover
Corn
Corn stover
Oats
1965
Alfalfa
Corn
Corn silage
Oats
Reed canary grass
1966
Alfalfa
Corn
Corn silage
Reed canary grass
1967
Corn
Corn silage
Reed canary grass
Unit
bu/acre
bu/acre
tons/acre
tons /acre
tons /acre
bu/acre
tons /acre
bu/acre
tons/acre
bu/acre
tons /acre
bu/acre
tons /acre
tons/acre
bu/acre
tons /acre
tons /acre
bu/acre
tons/acre
tons/acre
0 in./wk
48
73
2.18
2.48
1.76
81
3. 58
82
2.27
63
3.11
45
--
1.95
18a 33b
2.7S3 2.47b
,-
93C 87d
4.67C --
--
1 in./wk
45
103
3.73
4.90
5.30
121
7.29
124
4.67
114
3.93
80
--
3.86
1153 98b
9.023 4.4Sb
--
96C 79d
4.47C
--
2 in./wk
54
105
5.12
4.59
5.12
116
8.48
97
S.42
111
4.32
73
6.13
4.38
140a 115b
7.53a 5.68b
4.32a -
116C 80d
4.42C
7.03° -
a. 19-in. row.
b. 38-in. row.
c. 20-in. row.
d. 40-in. row.
58
-------
Bromegrass grown in soil with as high as 680 mg/L of lead
had only 34.5 mg/L of lead in the leaves [133]. This is
well below the 150 mg/L level of toxicity to cattle and
horses and caused no detrimental effects on the plants
[133].
The plants will not be harmed by pathogenic organisms but
animals that consume the plants could be harmed. Organisms
can enter plants through bruises or cuts but generally they
are not adsorbed by the plants.
Groundwater
Nutrients that are not used by plants or fixed in the soil
can leach down to groundwater and cause contamination. The
major element of concern is nitrogen. Nitrogen in the
nitrate form is used by plants for the growth process.
Nitrates that are not utilized are highly mobile and will
leach down to the groundwater. If concentrations are high
enough, the groundwater can become contaminated and unsuit-
able for domestic consumption. The U.S. Public Health
Service Drinking Water Standards recommend a concentration
limit of 10 mg/L for nitrate nitrogen.
Phosphorus in the wastewater may also leach to the ground-
water if it is not used by the crop or fixed by the soil;
however, this occurrence is rare in irrigation practice.
Soils with appreciable organic or clay contents adsorb
practically all of the phosphorus applied by wastewater
irrigation.
Organics can appear in groundwater when there is a high
application rate of wastewater or when there is an open soil,
such as sand or gravel, with a high percolation rate.
Organics are usually broken down by microorganisms and used
by plants. Even phenols and other hydrocarbons are acted
upon by bacteria at slow rates. With open soils, the water
carries the organics through the soil too fast for the bac-
terial action to take place. High concentrations of phenols
can be toxic to the bacteria and therefore no removal will
take place.
Toxic compounds can be changed by the chemical reaction of
cation exchange and can be rendered nontoxic by bacteria
under cometabolism [82] . 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.
Enteric organisms usually do not reach the groundwater
because they are removed or die out before the groundwater
59
-------
level is reached [53, 55]. Where crops are grown, the
groundwater is usually kept low enough so that the organisms
are eliminated from the percolating water before it reaches
the groundwater.
The IDS 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 occurred at Ventura in
Southern California. The applied irrigation water had a
TDS concentration of 1,702 mg/L and the test wells had con-
centrations of up to 8,128 mg/L [120].
Air
Spray irrigation has the inherent problem of aerosol travel
of water. The higher the pressure at the nozzle, the finer
the droplet and hence the longer the travel distance.
Airborne pathogens are a matter of concern and study [110,
117] and will be discussed further under "Aerosols." Some
irrigation sites have 50- to 200-foot buffer zones or rows
of trees around the irrigation area so that the travel of
the airborne droplets is limited within the site.
Odors caused by anaerobically decomposing organics can be
troublesome. The positive solution to the problem is to
eliminate the cause of the odors. An examination of the
operating procedures may indicate an overloading of the
soil, or an examination of the ground may indicate that the
surface is sealed. Corrective action of extensive drying
or surface scarifying to eliminate the cause of odors must
be taken to avoid complaints.
PUBLIC HEALTH CONSIDERATIONS
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) the chemical compounds present in waste -
water that can cause health problems, and (3) the propaga-
tion of insects that could be vectors in disease
transmission.
The passing of the Federal Water Pollution Control Act
Amendments of 1971 and 1972 has drawn attention to the use
of wastewater for irrigation. Stricter laws and regulations
on water pollution and land application will undoubtedly be
passed in the future.
60
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Regulations by State Agencies
.Each state has the legal power to protect the public health
of its people. Each state can act separately and independ-
ently in making laws; however, the state legislatures do
not generally have the time or technical competence to en-
force the laws, so they delegate the authority to the state
boards of health [23] .
There is no uniform pattern to the regulations in the United
States. In 1968, Coerver [23] indicated that 11 states had
a specific policy toward sewage irrigation, while in 1972
at least 17 states had specific regulations [21] . 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 disin-
fected sewage on fruits and vegetables which are eaten raw.
Other states ban the use of any sewage effluent for irriga-
tion 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
[111].
Most states have no specific regulations covering irriga-
tion of crops with effluent. States with long histories of
irrigation, such as Arizona and California, have recognized
the need for this resource and have passed regulations con-
trolling the use of effluents. Other states, with plentiful
water supplies and no need for irrigation, have ignored
irrigation of crops with effluent altogether [21] . The
individual State Health Department should be contacted for
specific land application regulations.
Survival of Pathogens
The survival of pathogenic bacteria and viruses on and in
soil, in sprayed aerosol droplets, and on vegetables ha.,
received considerable attention. It is important to realize
that any connection between pathogens spread on land during
irrigation and the contraction of disease in animals or man
would take a long and complex path of epidemiological
events. Nevertheless, questions have been raised, concern
exists, and precautions should be taken in dealing with the
possible disease transmission.
Pathogens in Soil 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. A list-
ing of organisms and their reported survival times in soil,
on crops, or in water is included in Table 13.
61
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Table 13. Survival Times of Organisms [111]
Organism
Media
Survival
time
Anthrax bacteria
Ascaris eggs
B.dysenteriae
flexner
B.typhosa
Cholera vibrios
Coliform
Entamoeba
histolytica
Enteroviruses
Hookworm larvae
Leptospira
Liver fluke cysts
Poliovirus
In water and sewage
On vegetables
On irrigated soil
In soil
In water containing humus
In water
In soil
On vegetables
On spinach, lettuce
On cucumbers
On nonacid vegetables
On onions, garlic,
oranges, lemons,
lentils, grapes ,
rice and dates
On grass
On clover leaves
On clover at 40-601
humidity
On lucerne
On vegetables (tomatoes)
On surface of soil
At -17 deg C
On vegetables
In water
On roots of bean plants
In soil
On tomato and pea roots
In soil
In river water
In sewage
In drainage water
In dry hay
In improperly dried hay
In polluted water at
20 deg C
19 days
27-35 days
2-3 years
6 years
160 days
7-30 days
29-70 days
31 days
22-29 days
7 days
2 days
Hours to 3 days
14 days
12-14 days
6 days
34 days
35 days
38 days
46-73 days
3 days
Months
At least 4 days
12 days
4-6 days
6 weeks
8 days
30 days
32 days
Few weeks
Over a year
20 days
62
-------
Table 13. (Continued)
Organism
Salmonella
Schistosoma ova
Shigella
Streptococci
S. typhi
Tubercle bacteria
Typhoid bacilli
Vibrio comma
Media
On grass (raw sewage)
On clover (settled sewage)
On vegetables
On beet leaves
On grass
On surface of soil and
potatoes
On carrots
On cabbage and gooseberries
In sandy soil - sterilized
In sandy soil - unsterilized
On surface of soil (raw'
sewage)
In lower layers of soil
On surface of soils (stored
sewage)
In air dried, digested sludge
In digestion tanks
In sludge at 60-75 deg F (dry)
In septic tank
On grass (raw sewage)
On vegetables
In soil
On surface of soil
In water containing humus
On grass
In soil
In water
In loam and sand
In muck
In river water
In sewage
Survival
time
6 weeks*
12 days
7-40 days
3 weeks
Over winter
40 days+
10 days*
5 days*
24 weeks
5-12 weeks
46 days
70 days
15-23 days
17 weeks*
3 months
3 weeks
2-3 weeks
6 weeks
7 days
35-63 days
38 days
87-104 days
10-14 days
6 months*
1-3 months
7-17 days
40 days
32 days
5 days
63
-------
In relation to the survival of coliform organisms, some
bacteria do survive for a longer time. Although the sur-
vival of viruses in soil has been essentially unexplored>
there is evidence of their inactivation in soil [28, 33].
Aerosols The travel time and distance of bacteria in air
has been studied in the United States and in Europe. In
the study reported by Merz [79] it is concluded that the
bacterial travel is limited to the distance of travel
of the mist from sprinklers. Sepp [111] 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.
Low trajectory nozzles and screens of trees and shrubs can
be used to limit bacterial travel. The traveling rig
sprinklers designed for Muskegon, Michigan, have been modi-
fied to direct the spray trajectory downward. Studies of
aerosol drift are being planned for the Muskegon operation
[117].
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 [94],
Sorber [117] indicates that a 50-micron water droplet will
evaporate in 0.31 second in air, with 50 percent relative
humidity and a temperature of 22 deg C. Thus, dessication
is a major factor in bacterial die-off.
Pathogens on Vegetables In general, bacteria will not
enter healthy, unbroken vegetables; however, broken,
bruised, or unhealthy plants and vegetables are easily sus-
ceptible to attack by bacteria. The cleaning of vegetables
with plain water, or detergents is ineffective as a means
of bacteriological decontamination. Germicidal rinses of
chlorine and its compounds are superior to water and deter-
gents, but are unreliable. The only reliable method of
decontamination is pasteurization at 60 deg C for 5 minutes
[103].
Chemical Compounds
If certain chemical compounds reach the groundwater, they
may present a health hazard should the groundwater be used
as a potable water supply. Compounds that may reach the
groundwater as a result of land application of wastewater
include nitrates, TDS, and trace organics.
64
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Nitrate nitrogen has been demonstrated to be the causative
agent of methemoglobinemia in children. Ingested nitrate
is reduced to nitrite in the digestive tract. The nitrites
are then adsorbed into the bloodstream, ultimately causing
suffocation of the child by reducing the ability of the
blood to carry oxygen [133] .
Irrigation with \\rastewater will normally increase the IDS
content of the percolating water. In drinking water, high
IDS levels can be harmful to people with cardiac, viral,
or circulatory diseases [117] .
Finally, the toxicity of certain constituents of the COD,
often called trace organics, is of concern. The possi-
bility of such compounds reaching the groundwater, however,
is slight.
Insect and Rodent Control
The control of insects and rodents on a wastewater irriga-
tion site is more critical than on a conventional irrigation
site because of the possibility of contamination by bacteria
from the wastewater. A three-year study at Pennsylvania
State University revealed that the use of wastewater to
irrigate the forested land had no adverse effect on the
wildlife population. Gophers and muskrats can be a problem
for flood irrigation or ridge and furrow sites by burrowing
in the dikes. Such problems have been reported at Woodland,
California, and Westby, Wisconsin. Trapping and other con-
ventional methods of removal have arrested the problem. In
the Pennsylvania State study, it was reported that mosquitoes
increased in population mainly because of the wetter environ-
ment and the availability of standing puddles for breeding
[90].
Mosquitoes will propagate in tepid water standing only a
few days, which enforces the point about the necessity for
drying periods between wastewater applications. Although
mosquitoes may be controlled by use of insecticides, such
practices may involve some degree of environmental degrada-
tion and usually serve only as a temporary solution.
IRRIGATION ABANDONMENT
In this assessment of the current state-of-the-art, an in-
vestigation was made into reasons for abandoning irrigation
at selected sites. Selection was made of 24 sites in
California and Texas and a number of interesting reasons
were found for abandonment. Generally, the irrigation
practice was abandoned when the city expanded its sewage
65
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treatment facilities and either changed plant locations or
had inadequate land available to expand the irrigation
system. A complete description of each case is given in
Appendix B.
Irrigation with municipal wastewater was abandoned at
many locations because of a variety of often interrelated
reasons. Sometimes a single event, such as the death or
retirement of a "key manager, or the receipt of a complaint,
will result in disenchantment of the city officials with
irrigation as a disposal method. Limits of liquid, organic,
and nitrogen loadings, land use changes, political and
environmental changes, and improper management will be
discussed as reasons for irrigation abandonment.
Limits of Loading
The soil system may become overloaded with water, organics,
nitrogen, or toxic substances. A survey conducted in 1934
and again in 1937 found that in the interim six cities had
abandoned irrigation: two because of inadequate infiltra-
tion rates; two because of insufficient land; one because
of high alkali in the soil; and one because of high salt in
the wastewater [47].
Liquid Loading The upper limits of loadings depend upon
the soil type and crop requirements or tolerances. As indi-
cated under "Design Criteria," 4 in./wk is the dividing line
between the classifications of irrigation and infiltration-
percolation. At Quincy, Washington, a rate of 7.2 in./wk
is being applied to corn and wheat. This rate results in
occasional drowning of the crops and the City plans to ex-
pand its acreage. An irrigation rate of 4.3 in./wk on
loamy soil at Orland, California, was excessive and the re-
sult was irrigation abandonment in 1964.
Organic Loading^ The upper limits of organic loadings are
rarely approached in wastewater irrigation practice. A
figure of 30 tons/acre/yr has been found to be a satisfac-
tory loading for septic tank effluent [123]. The highest
loading determined from this study for municipal effluent
was 15.9 tons of BOD/acre/yr at Fresno, California; how-
ever, odor problems have resulted. The upper limits of
organic loadings will more likely be tested by land appli-
cation of sludge or industrial wastewater.
Nitrogen Loading Despite the low hydraulic loading at
Lubbock" Texas, the nitrogen loading of only 310 Ib/acre/yr
has resulted in a fourfold buildup of nitrates in the
groundwater over 40 years [136]. In a northern Michigan
forested area, liquid applications of 2.5 in./wk in loamy
66
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sand have been satisfactory", except for a high nitrogen
buildup. The buildup occurred with a nitrogen loading of
170 Ib/acre/yr after one year of operation [129]. At
South Lake Tahoe, California, the runoff of approximately
50 percent of the influent nitrogen was a significant
factor in abandonment of land application.
Toxic Buildup - Buildup of IDS, sodium, and heavy metals in
the soilcancause site abandonment. Leaching, or the
addition of soil amendments, may alleviate the toxicity; in
the case of TDS or boron, a more salt tolerant crop may be
found. At Kingsburg, California, the presence of cannery
lye peeler waste has led to irrigation abandonment. It has
been reported that, in France, phytotoxic levels of copper
and zinc have built up in the soil, but it has taken over
100 years for this to occur [125].
Land Use Changes
Changes in land use patterns can have a serious effect on
irrigation projects. Increased population around the sewage
treatment plant at Pasadena, California, led to odor com-
plaints and the abandonment of the plant. In the case of
the Talbert Valley Water District in Southern California
where over 2,800 acres were being irrigated in 1957, the
land use changed so rapidly from agricultural to residential
that the District was out of business by 1964.
A form of urbanization that can cause the abandonment of a
site is the change of location of the treatment plant.
Many towns as they grow find that the existing treatment
plant is too small and the treatment is inadequate. Often,
when a new plant is constructed, a new location is selected
and the existing irrigation system is eliminated. The town
of St. Helena, California, built a new treatment plant and
ended a wastewater irrigation system that had been in oper-
ation for over 60 years. The town of Ukiah, California,
also built a new treatment plant at a new location, thus
terminating the irrigation practice.
Political and Environmental Changes
The regulations passed in most states against irrigation
with untreated sewage caused the abandonment of many sewage
farms. Requirements for increased levels of treatment prior
to land application may also lead to irrigation abandonment.
An environmental change that could cause abandonment is
groundwater degradation. The buildup of nitrates or salts
in the groundwater can make -it unsuitable for consumption.
If requirements are imposed on wastewater irrigation which
67
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define groundwater pollution as the increase in any con-
stituent above the U.S. Public Health Service limits for
drinking water, increased monitoring and groundwater table
control will be necessary.
Where water is scarce, the application of treated effluent
to the land, with subsequent loss to evaporation and the
groundwater, serves to reduce summer stream floivs. In
streams where treatment plant effluent represents a major
portion of the summer flow, other water uses, such as fish
propagation and recreation, may be augmented by stream dis-
charge instead of land application. At Childress, Texas,
discharge to a dry creek in the summer was a satisfactory
method until one farmer periodically withdrew the wastewater
for irrigation. The resultant ponding and odor complaints
led to discharge to a different creek.
Lack of Management
The lack of competent management has resulted in the aban-
donment of many irrigation systems. In Augusta, Maine, the
death of the chief operator ended the use of irrigation.
Similarly, in Stamford, Texas, it was the retirement of the
chief operator that ended the use of irrigation. It is not
clear whether other systems, abandoned for various reasons,
could have remained viable under competent and forceful
management.
The lack of a satisfactory arrangement between owner and
lessee has resulted in system abandonment [47] . It appears
that a voluntary system at Woodland, California, where
the farmer calls for the irrigation water when he needs
it, works well. The system at Woodland has the flexibility
of discharging to percolation basins, duck ponds, or hold-
ing ponds when the lessee is not irrigating. On the other
hand, voluntary irrigation has been a failure at Fresno,
California.
68
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SECTION V
INFILTRATION-PERCOLATION OF MUNICIPAL WASTEWATER
Land application of municipal wastewater by infiltration-
percolation is often referred to as groundwater recharge
because the major portion of the wastewater applied infil-
trates the soil surface, percolates through the soil matrix,
and eventually reaches the native groundwater. The waste -
water is renovated as it travels through the soil matrix by
natural physical, chemical, and biological processes.
Depending upon its final quality, the recharged water may
be recovered and used for irrigation, recreation, or munici-
pal or industrial supply.
The feasibility of this approach has been demonstrated by
systems operating at Hemet, California [119], Phoenix
(Flushing Meadows), Arizona [100], Whittier Narrows,
California [69], and Santee, California [77], These sys-
tems, which have been well studied, represent examples of
planned land treatment and recovery. Other systems, such
as those at Lake George, New York [6], Vineland, New
Jersey, Marysville, California, and Westby, Wisconsin [10],
represent examples of direct recycling of effluent to the
land by infiltration-percolation. The scope of this section
includes both types of systems, but major emphasis is
placed on engineered systems involving groundwater recharge.
The purpose of the discussion is to identify and evaluate
approaches currently used for the location, planning,
design, and operation of such systems.- As in Section
IV, the major topics covered include (1) system design,
(2) management and operation, (3) environmental effects,
(4) public health requirements, and (5) analysis of system
failures.
SYSTEM DESIGN
The elements of system design include site selection and
criteria for wastewater pretreatment, loading rates, type
of basin surface, and recovery.
69
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SjLte Selection
The most important factors in site selection are soil drain-
ability and the movement, level, and quality of groundwater.
Other related selection factors include soil type and depth,
underlying geologic formations, and surface topography.
Soil Charac_terisjtics Soils with infiltration rates on the
order of 4 to^LTTrT./day or more are necessary for success-
ful use of the infiltration-percolation approach.
Acceptable soil types include sand, sandy loams, and 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. A silt loam soil has been
utilized with some success in Westby, Wisconsin, with an
annual loading of up to 45 feet (10.4 in./wk) [124].
Recently, loadings have been reduced to 8.4 in./wk but pro-
longed rains have continued the overloaded conditions.
Of equal importance to infiltration rates of the topsoil
are the percolation rates of lower soil layers. Permea-
bility, either horizontal movement or vertical percolation,
must equal or exceed infiltration rates.
The depth of soil layers and the permeability of each layer
will affect the overall percolation rate. The system may
be limited by the presence of a shallow clay layer between
two sandy layers. The high permeability of the lower layer
will be effectively negated by the presence of such a clay
lens. Soil borings must be taken at a site to obtain
the soil profile. A site with extensive clay layers, or
other impermeable formations near the surface, should be
rejected as a possible site.
Hydrologic Conditions The depth, movement, and quality of
groundwater are the most important hydrologic factors in
site selection. Wastewater percolating through soil will
create a mound or pseudo-water table as shown on Figure 1
in Section III. If the normal water table were less than
10 feet from the surface, the recharge mound would likely
intersect the surface with resultant ponding. A depth of
15 feet from surface to groundwater is considered a minimum
for maintenance of long term liquid loading rates and
effective renovation [124] . The movement of groundwater
will be discussed along with aquifers under "Geologic
Conditions."
The quality of the groundwater is critical, whether it
is excellent or brackish. If it is of high quality, the
recharge may degrade it, but if it is brackish, recharging
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could improve its quality. For example, the groundwater
recharge operations at Hemet and Los Angeles (Hyperion),
California, are effectively limiting salt water intrusion
into the groundwater from the ocean. On the other hand,
at Phoenix, where native groundwater quality is also poor,
the recharge system is attempting to recover the renovated
water before it mixes with, and is degraded by, the native
groundwater.
Precipitation will add to the liquid loading, both directly
as it falls and indirectly by increasing adjacent stream
flows which leads to a general rise in the water table. At
Hemet, heavy and prolonged rains led to ponding and tempo-
rary abandonment of recharging [124].
Geologic Conditions The parent material of a soil is the
original material, usually erodible rock such as soft sedi-
mentary rock, from which the soil was created. The parent
material will give the soil its chemical and mechanical
properties. Knowledge of parent material and existing rock
formations is important in assessing the water holding
characteristics and transmissibility of a soil system.
The ability of a soil to transmit groundwater determines
its suitability to act as an aquifer. An aquifer by defi-
nition is a geologic formation which contains water and
transmits it from one point to another in quantities suffi-
cient to permit economic development. In contrast, ""an
aquiclude is a formation which contains water but cannot
transmit it rapidly enough to furnish a significant supply
to a well or spring.
A soil with high porosity does not necessarily make a good
aquifer. Porosity is the ratio of pore or void volume to
the total volume. The more accurate measure of the poten-
tial of a soil type is the specific yield. The specific
yield is the ratio of water that will drain freely from
the material to the total volume of the material. Soil
types and their hydraulic characteristics as aquifers
are given in Table 14. Most of the productive aquifers
in the United States are of the sand and gravel type.
Minimization of the spread of renovated v^ater into an out-
side aquifer can be accomplished by surrounding the system
with wells or drains to interrupt the flow. Evaluating the
hydraulics of groundwater flow is an area of increased com-
puter use and modeling. At Flushing Meadows, the hori-
zontal and vertical conductivities were calculated by use
of an electrical resistance network analog [14].
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Table 14. Soil Types and Hydraulic
Characteristics [60]
Porosity, Specific yield, Permeability,
Material I I gpd/sq
Clay
Sand
Gravel
Gravel and sand
Sandstone
Dense limestone
Granite
45
35
25
20
15
5
1
3
25
22
16
8
2
0.5
1
800
5,000
2,000
700
1
0.1.
a. The permeability shown is the discharge in gallons per
day through an area of 1 sq ft under a gradient of
1 ft/ft at 60 deg F [60].
Topography The site topography can be adapted to suit
infiltration-percolation site requirements. Since high
rate disposal is desired, ponding or flooding the basin is
the usual mode of application. A site should be flat or
gently sloping so that it can be diked into basins. Too
much slope would create lateral percolation which could
affect the percolation rates of the lower basins. At
Westby, Wisconsin, basins have been terraced into a 5 per-
cent sloping hillside, but there is some effect of lateral
percolation.
Design Criteria
In the design of an infiltration-percolation system, the
important criteria are (1) wastewater quality and pretreat-
ment requirements, (2) liquid and organic loading rates,
(3) type of basin surface, (4) distribution system,
(5) provisions for seasonal changes, and (6] renovated
water recovery.
Wastewater Quality and Pretreatment Requirements The
quality of wastewater to be applied to a spreading basin is
considered a design parameter because it directly affects
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the land area required and the operation and management of
an infiltration-percolation system. The principal concern
is.the determination of the quality of wastewater that may
be used without seriously reducing natural infiltration
capacity and without degrading groundwater quality.
The major quality factors affecting the infiltration capac-
ity of a system are the concentration of suspended solids
and organic material. These wastewater constituents hasten
the clogging of the soil surface through several complex
mechanisms. Surface pore space is reduced by deposition of
suspended solids and bacterial growth associated with the
presence of organic material. As a result, the diffusion
of oxygen into the soil is reduced. Unless the pore space
is reopened and aerobic conditions are maintained in the
soil through periodic drying of the spreading basin, anaer-
obic bacterial activity will begin. This activity, with
its insoluble slimes as byproducts, is the major cause of
severe soil clogging [65], The result of the clogging
phenomena associated with suspended solids and soluble or-
ganic material is that the quality of the water in terms of
these constituents will dictate the length of the applica-
tion and drying periods required to sustain the infiltration
rates of spreading basins. This application scheduling de-
termines the hydraulic loading of the basin and hence the
land area required for the system. In essence, the better
the quality of wastewater in terms of suspended solids and
organic matter, the smaller the area required for
infiltration-percolation. This statement must be qualified,
because it has been found that a certain amount of organic
material has a beneficial effect on the infiltration capac-
ity of a soil by acting as a granulating agent in soils
during drying [65].
The degree of pretreatment required for an infiltration-
percolation system to maintain infiltration capacity depends
on the primary objective of the system. If the objective
is to maximize the hydraulic acceptance of the system so as
to minimize the land area required for spreading, then a
high degree of pretreatment (secondary treatment or better)
is justified. On the other hand, if the objective of the
system is to use the soil matrix as a treatment system,
then a lesser degree of pretreatment may be justified if
proven operationally feasible by in situ pilot studies.
Primary sedimentation should be considered the minimum form
of pretreatment to avoid operating and nuisance problems
associated with coarse sewage solids. The feasibility of
using primary effluent for infiltration-percolation has
been demonstrated in the laboratory [26] and in the field
[40]. Use of primary effluent will create a higher risk
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of operating problems due to severe clogging, especially at
low temperatures [26]. The major long term impact of pri-
mary effluent will be to shorten the useful life of a sys-
tem because of more rapid accumulation of nondegradable
material in the soil.
It has been suggested that secondary biological treatment
be the minimum degree of pretreatment for municipal
infiltration-percolation systems to avoid the risk of fre-
quent clogging [133]. Secondary effluent in this case
refers to effluents with BOD and suspended solids concen-
tration in the range from 10 to 30 mg/L [133]. All high
rate systems in the United States reported in the litera-
ture provide a secondary treatment prior to spreading [6,
69, 77, 100, 119]. For the many moderate rate systems,
primary, intermediate, and secondary effluents have been
used successfully.
The presence of algae in applied wastewater has contributed
to soil clogging problems at the groundwater recharge site
in Hemet, California [119]. Researchers have found that
algal growth in holding ponds has resulted in a tenfold in-
crease in suspended solids concentration in secondary efflu-
ent to be applied to spreading basins. The algal solids
hastened clogging and forced adoption of a longer drying
cycle. This experience indicates that pretreatment to con-
trol algae growth may be necessary for systems with condi-
tions that are conducive to algae growth.
The degree of pretreatment required to protect the ground-
water quality depends on (1) the characteristics of the
wastewater, (2) the renovative efficiency of the soil sys-
tem, and (3] the beneficial use intended for the renovated
water.
It has been well established that natural soil systems suit-
able for infiltration-percolation are highly efficient
biological filters that are capable of almost complete re-
moval of organic material, suspended solids, enteric bac-
teria, and viruses within the first few feet of percolation
[3, 10, 15, 40, 41, 104]. These constituents are therefore
not of general concern with respect to groundwater quality
protection provided that the infiltration-percolation
system is properly operated.
Other wastewater constituents which could affect groundwater
quality include phosphorus, metals, boron, nitrogen, and
dissolved solids. Because of the nature of the removal
processes, soil systems have a finite capacity to remove
phosphorus and constituents such as metals which depend on
adsorption as the primary removal mechanism. In many cases,
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however, this capacity is quite large. If the presence of
phosphorus in the final renovated water is undesirable for
the beneficial use intended, as in the case of recreational
lakes, then pretreatment to remove phosphorus may be re-
quired if the removal efficiency of the soil system is
inadequate or the retention capacity is reached.
The heavy metals are present in municipal wastewaters in
trace amounts. These metals are removed from solution by
the adsorptive process and by precipitation and ion exchange
in the soil. Accumulation of metals in the soil due to
adsorption presents the risk of metal toxicity to plants and
microorganisms in the soil. At present it is not economical
to remove trace .quantities of metals in conventional treat-
ment plants. Therefore, in soil systems, as in receiving
waters, the presence of some of the trace metals will be of
concern. It has been suggested that it might be possible to
restore the metal removal capacity of a saturated soil sys-
tem by lowering the pH of the soil, leaching out the re-
tained metals, and collecting and treating the leachate
[133].
It is apparent that further research is required on the
effects of inorganic materials on the operating life of a
soil system and on restorative measures to offset these
effects.
Boron is removed in the soil matrix by adsorption on soil
particles containing aluminum oxides and iron. These mate-
rials are essentially absent in sandy soils that are suit-
able for infiltration-percolation; therefore, boron is
generally passed on to the groundwater. If the recharged
groundwater is to be used for irrigation, the concentration
of boron is of concern. This concentration in municipal
wastewater may increase in the future because of increased
use of detergents containing borax or perborate [100] .
However, boron is not expected to restrict the use of
infiltration-percolation, except in areas having a high con-
centration of natural boron in the muncipal water supply
which is. then transferred to the wastewater. Pretreatment
to remove boron alone is not considered economically
feasible.
Nitrogen contained in municipal wastewaters applied to
infiltration-percolation sites may take any of the pathways
described in Section III under the nitrogen cycle. In con-
trast to irrigation systems, however, uptake of nitrogen
by plants is not a significant removal mechanism for
infiltration-percolation systems, even those with vegetated
75
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spreading basins. This is due to the relatively high vol-
ume of wastewater applied per unit of soil for these
systems [56]. In addition, the lower clay and organic
content of soils suitable for infiltration-percolation re-
sults in lower fixation capacity for ammonium ions. These
conditions can lead to a significant loss of nitrogen to
the groundwater as nitrate which can contaminate groundwater
used for potable water supply or accelerate eutrophication
in lakes and streams receiving recharged water. The presence
of nitrates in groundwater used exclusively for crop irri-
gation is of less concern because plant uptake will remove
significant quantities of nitrogen.
The loss of nitrates to the groundwater may be reduced
either by pretreatment or by operating techniques which
promote nitrogen removal by the other soil removal
mechanisms. These operating techniques are discussed later
in this section. In-plant pretreatment methods to remove
nitrogen prior to land application include biological
nitrification-denitrification, break point chlorination,
ammonia stripping, and selective ion exchange. Another
technique which can be considered pretreatment is dilution
of the wastewater with low nitrate water prior to spreading.
This form of pretreatment is successfully practiced at
the Whittier Narrows, California, recharge site [69].
Dilution of recharged water by blending with in. situ ground-
water has been suggested as a means of mitigating the ef-
fects of high concentrations of nitrate in the percolate
[69]. Blending of groundwaters, however, is a slow process
requiring long detention times and long distances of hori-
zontal travel by the recharged water. The feasibility of
this practice therefore depends on the characteristics of
the aquifer in the vicinity of the recharge area. If
blending of natural and recharged groundwater is to be
allowed, the natural groundwater should be receiving ade-
quate additional replenishment with low nitrate waters
to avoid a long term accumulation of nitrates.
It has been suggested that wastewater should be treated to
convert all nitrogen to nitrate prior to infiltration-
percolation to avoid adverse effects associated with nitri-
fication in the soil [50]. The possible effects include:
(1) reduction in the BOD removal efficiency of the soil and
reduction in the length of time aerobic conditions can be
maintained in the soil due to the high oxygen demand of the
nitrification process [69] ; (2) increased mineralization ,
of groundwaters due to release of hydrogen ions during
nitrification and subsequent dissolving of calcerous rock
[50] ; and (3) limitation of nitrogen removal by biological
denitrification in the soil [133]. These effects, however,
have not been specifically documented by field experience.
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Further research to provide such documentation is warranted
to provide a basis for determining pretreatment requirements.
In fact, the coupling of the theory of environmental re-
sponses of the soil matrix, such as the nitrogen cycle, to
practical field experience is generally lacking at this
point. Research in this area is needed to optimize the
application of in-plant treatment in conjunction with land
application systems, especially infiltration-percolation
systems.
Liquid Loading Rates Infiltration-percolation systems
have liquid loadings ranging from 18 to 500 ft/yr or, on a
weekly basis, 0.3 to 10 ft/wk. Two of the most publicized
sites, Whittier Narrows, California, and Flushing Meadows,
Arizona, have operated at liquid loading rates as high as
10 ft/wk and 8 ft/wk, respectively [69, 100].
The design rate must be determined on the basis of pilot
work. The percolation rate determined from this work
should be used for loading rate design provided that it is
not significantly greater than the infiltration rate.
During actual operation the infiltration rate may become
limiting because of clogging; however, with proper manage-
ment the initial rates can be restored.
In the course of operation the liquid loading rate will
undoubtedly change in response to climate, wastewater char-
acteristics, or groundwater levels. The rates may also be
modified in an attempt to improve the renovation in terms
of nitrogen or phosphorus.
Organic Loading Rates Organic loading rates depend upon
the wastewater characteristics, the treatment system objec-
tives, and the liquid loading rates. Suggested loading
rates reported in the literature range from 7,400 lb/acre/
yr for silt loam soil to 60,000 Ib/acre/yr for sandy soil
[123]. These loadings are based on the 5-day BOD. Actual
BOD loadings in pounds per acre per year for operating sys-
tems are listed in Table 15. It should be noted that
although the liquid loading rates in Table 15 are on the
order of 50 to 100 times as large as those for irrigation
sites, the organic loading rates are only about 5 times as
large.
The BODs should not be the only criterion in organic
loadings. Total oxygen demand must also be considered. In
the case of Whittier Narrows, subsurface anaerobic condi-
tions have developed as a result of the nitrification of
about 20 mg/L of ammonia nitrogen and long term carbonaceous
oxygen demand. Although the effluent BODs was about 5 mg/L,
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Table 15. Existing Organic and Liquid
Loading Rates for Infiltration-Percolation
Organic loading, Liquid loading,
Location Ib/acre/yr ft/yr Reference
Hyperion,
California
Santee,
California
Flushing Meadows,
Arizona
Westby,
Wisconsin
Whittier Narrows,
California
Lake George,
New York
34,000
21,000
10,900
9,700
7,100
6,800
365
270
400
36
520
65
58
77
100
--
69
--
the ultimate oxygen demand, including that from nitrifica-
tion, was about 150 mg/L [69].
Type of Basin Surface The surface of an infiltration-
percolation basin should be designed to disperse the
clogging material applied [65] . The two principal methods
of accomplishing this dispersion are: (1) growing vegeta-
tion on infiltrative surfaces, thus providing root channels
with attendant soil expansion, and (2) covering surfaces
with graded sand or gravel, thus encouraging clogging action
in a matrix having larger pore spaces than the soil. On the
basis of the literature there is no general agreement on
the best type of basin surface. What has proved successful
at one location has worked poorly at others. Selection of
the type of basin surface should be based on comparative
pilot studies at the infiltration site. Consideration
should be given to renovative capacity and maintenance re-
quired in addition to infiltration capacity. The relative
merits of the two types of basin surface are presented in
the following discussion.
78
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The effect of vegetated surfaces is illustrated at Flushing
Meadows. In 1969 a comparison of the six basins was
performed. Four were vegetated, one was left bare, and one
was covered with gravel. The infiltration rate for the
vegetated basins was 25 percent greater than those for the
bare basin, and the bare basin showed greater infiltration
rates than the gravel covered one [16, 134].
The advantages of vegetation include: (1) protection of
soil from the impact of water droplets in areas of high
rainfall, (2) additional nutrient removal if the vegetation
is harvested (usually less than 5 percent) and (3) possible
promotion of denitrification. Further research is required
to substantiate the thesis that increased soil carbon
around roots promotes increased denitrification.
The disadvantages of vegetation include increased main-
tenance and lower recharge depths. Loading cycles must be
adjusted to promote plant growth in the early growing sea-
son and to permit harvesting. At Flushing Meadows the
water depth, which was found to be directly proportional to
infiltration rates, was restricted to avoid complete
submergence. Giant bermuda grass proved to be the most
suitable vegetation although rice and sudan grass were also
tried [100] .
The effect of nonvegetated surfaces is illustrated at the
Whittier Narrows test basin, where 6 inches of pea gravel
was spread over the bare soil to eliminate plant growth and
decrease maintenance [69] . It was concluded that this
layer was a major contributing factor to higher infiltra-
tion rates. On the other hand, studies with gravel layers
at the Hemet and the Flushing Meadows recharge sites indi-
cated that a gravel cover was not particularly effective in
maintaining infiltration capacity [100, 119]. Researchers
at Flushing Meadows hypothesized that the negative effect
of the gravel layer on infiltration was due to a mulching
action of the gravel layer and resulting poor drying of the
underlying soil.
When using a gravel cover it has been suggested that abrupt
changes in particle size should be avoided between the sur-
face cover material and the soil at the infiltrative surface
[65]. This precaution will prevent loss of infiltrative
surface area as a result of blinding by large particles and
will promote dispersion of clogging solids.
Distribution System The distribution system consists of
facilities to transfer wastewater to the site, outlet facil-
ities, and hydraulic controls.
79
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The transmission to the site can be by gravity or by
pumping. For some of the intermittent dosage systems, the
equivalent of 1 foot of water is applied in 30 minutes. The
flow rate would be about 5,000 gpm for an area of 0.5 acre
[131]. For long application periods, such as those at
Flushing Meadows, the application is by gravity. Most sites
simply have a single pipe from the source of wastewater to
the site. Measurement is by flowmeter for pumped systems
or by flume for gravity systems.
The outlet facilities usually consist of a single riser
pipe in each basin. At Detroit Lakes, Minnesota, the appli-
cation is bysprinklers [57]. Since most sites use the
flooding technique, however, no special equipment is needed.
Where velocities in one pipe are too high, a diffuser system
of two or three outlets can be used. The lower the water
velocity, the less erosion will occur at the outlet. A con-
crete splash pad is recommended at the outlet to distribute
the flow.
The hydraulic controls of an infiltration-percolation sys-
tem are not as sophisticated as for an irrigation system
because the higher hydraulic loading rates do not require
the fine control of an irrigation system. The infiltration
rates are higher and there is little concern for ponding or
vegetation damage. Since most sites are visited on a daily
basis, the operation of two valves or slide gates per day
requires minimum effort.
Provisions for Seasonal Chan ges The uncertainty of weather
patterns may require a. factor of safety in the amount of
land used or storage required. The climate will influence
the operation of the site, especially where freezing tem-
peratures are encountered for long periods of time. At
Lake George, New York, the drying period is doubled in the
winter to allow for the slower percolation rate. At this
site, the winter flow is about one-quarter of the summer
flow so the need for additional area does not occur.
At Hemet, California, three additional beds were constructed
for use when other beds are out of operation because of
maintenance requirements or emergency situations. The extra
beds add 43 percent more area to the system [119] .
The abnormal rainfall at Westby, Wisconsin, during the
winter of 1972-1973 has created problems with the
infiltration-percolation system. The extra water has taxed
the system to the limit, and the operation has had to
be altered to cope with the extra water. With little
storage and no extra beds for emergencies, the ridge and
furrow system has evolved into a series of holding ponds.
80
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For design purposes, a certain percentage of the design
area should be allotted for emergency situations. A reason-
able range for general use would be 10 to 25 percent with
20 percent as typical. This will depend on conditions
such as weather, available land, and the hazard involved
should emergencies occur.
Recovery of Renovated Water Recovery of renovated water
is being carried out at a number of sites. At Whittier
Narrows, the renovated water is pumped from the groundwater
by individual wells. At Flushing Meadows, it is planned
that the renovated water will be pumped to an irrigation
canal for unrestricted reuse [134]. At Santee, California,
the renovated water fills a series of four ponds that are
used for recreational purposes. Swimming, boating, and
fishing are some of the activities that take place on the
lakes [77] .
Recovery of renovated water can be an integral part of the
system design, as at Flushing Meadows and Santee [77, 100],
or it can be incidental with the normal withdrawal from the
groundwater basin as at Whittier Narrows and Hemet [69,
119].
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, contamination
can be prevented, especially with regard to nitrates. In
addition, renovated water recovered in this manner could
receive additional treatment or could be used exclusively
for purposes best suited to its quality, such as irrigation
or recreational lakes. Design of this type of recovery
system, however, requires a detailed knowledge of the sub-
surface geologic conditions and aquifer characteristics. A
sufficient detention time and distance of underground travel
must be allowed the percolated wastewater to permit renova-
tion to be complete.
MANAGEMENT AND OPERATION
Important aspects of infiltration-percolation system manage-
ment include (1) hydraulic loading cycles, (2) basin surface
management, (3) operational problems, (4) monitoring, and
(5) treatment efficiency.
Hydraulic Loading Cycles
It has been established that a schedule of intermittent
application of wastewater is required to maintain reasonable
infiltration rates and renovative capacities. At Hyperion
81
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and Flushing Meadows, continuous applications have been
attempted which showed a constant drop in infiltration rates
and a reduction of renovative capacity.
Optimum loading cycles will depend on the primary objective
of the system. For instance, an application cycle which
maximizes infiltration rates may minimize nitrogen removal
by denitrification. It is therefore impossible to predict
the optimum loading cycle for any one system [65]. The
variation in reported loading cycles for existing systems,
as shown in Table 16, illustrates this point. Experimenta-
tion is required to determine the best loading cycles con-
sistent 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. This activity helps break up the
clogging layer and free ammonium adsorption sites on clay
and humus materials. In addition, prevention of severe
anaerobic conditions through intermittent loading will
avoid the possibility of leaching degradable organics into
the groundwater.
Application frequency may affect the renovation that results
from adsorption, by changing the detention time of the
wastewater constituents in the soil matrix. The longer
the detention time, the higher the probability of contact
between wastewater constituent and adsorption site and
the greater the overall renovation. Resting periods may
also allow adsorbed ions to diffuse into interstices of
the adsorbent particles which frees the external adsorption
site. Further research is required to determine, in actual
field operation, the relationship between adsorption effec-
tiveness and application frequency.
Basin Surface Management
Where bare soil or gravel surfaces are used, they should be
scarified or raked when solids accumulate. The frequency
will depend upon the quality of the wastewater. More fre-
quent raking is needed when water with high solids content
is used. Operational experience will indicate the fre-
quency; a typical frequency is once a year. The methods
used have included shaving or sweeping [100], and disking,
scarifying, and rototilling [119].
For vegetated surfaces the need is for careful operation of
the loading cycle in the spring until the vegetation is
82
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Table 16. Existing Hydraulic Loading Cycles
Location
Flushing Meadows, Arizona
Maximum infiltration
Summer
Winter
Hyperion, California
Lake George, New York
Summer
Winter
Tel Aviv, Israel
Vineland, New Jersey
Nestby, Wisconsin
Whittier Narrows , California
Loading
objective
Increase
ammonium
adsorption
capacity
Maxinize
nitrogen
removal
Maximize
nitrogen
removal
Maximize
infiltration
rates
Maximize
infiltration
rates
Maximize
infiltration
rates
Maximize
renovation
Maximize
infiltration
rates
Maximize
infiltration
rates
Maximize
infiltration
rates
Application
period
2 days
2 wk
2 wk
Continuous3
0.5 hr
9 hr
9 hr
5-6 days
1-2 days
2 wk
9 hr
Resting
period
S days
10 days
20 days
23.5 hr
4-5 days
5-10 days
10-12 days
7-10 days
2 wk
15 hr
Reference
100
100
100
58
131
"
6
3
~ ""
10
69
a. Abandoned after 6 months.
83
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well established. The surface may be harrowed on an annual
basis to break up any solids buildup.
Operational Problems
Problems developed with infiltration-percolation systems
are generally related to the woather, mechanical breakdowns,
or. wastewater characteristics. At Hemet. and Westby, severe
prolonged rains have caused serious problems. At Hemet the
solution was temporary abandonment of the system, while at
Westby the rain and an overloaded plant may lead to perma-
nent abandonment. At Lake George the snow and ice do not
present serious problems. As the basins are flooded with
effluent the ice is merely floated up 7 to 8 inches and
serves to insulate the soil surface from further lowering
of the temperature.
Mechanical breakdowns can be minimized by preventive main-
tenance; however, standby pumps and excess spreading basins
are advisable.
At nearly all operating sites, problems relating to waste-
water characteristics, primarily clogging, have occurred
when abnormally high solids content water is applied to the.
land. At Whittier Narrows, the basin was taken out of
service until the plant effluent quality was stabilized.
At Flushing Meadows, the upper portions of the spreading
basins were converted to settling basins to reduce the sus-
pended solids content [15].
Monitoring
Monitoring is needed to maintain successful operation and
to avoid conditions leading to significant environmental
degradation. Flow meters or measuring flumes are necessary
to measure the wastewater application rate. Infiltration
rates will vary throughout the application period. For
example, at Flushing Meadows the infiltration rate de-
creases linearly with time from 2.5 ft/day to 1.5 ft/day
over the inundation period of 10 days. Should the infil-
tration rate, as monitored by flow recorders and/or level
recorders, decline more rapidly than usual or fail to
attain its original value after resting, measures must
be taken to remedy the situation.
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 a less frequent interval.
84
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Groundwater or percolate water quality should be sampled
for the same types of characteristics. The percolate water
sampling arrangement used at Whittier Narrows is shown on
Figure 8. For larger systems, sampling lysimeters have
been used [90] . A modified lysimeter called a suction
probe, which has been used by the Agricultural Extension
Service in California, is illustrated on Figure 9.
Sampling and recording wells should be established around
the spreading basin on the basis of the site selection
geological data. Samples should also be taken from pumped
recovery wells to determine final removal efficiencies.
Treatment Efficiency
Removal efficiencies for infiltration-percolation systems
are not as high as for irrigation systems because of higher
loading rates, coarser textured soils , and lower clay con-
tent of soils. Removal of some constituents, such as sus-
pended solids and bacteria, will be quite comparable to
that of irrigation systems. Removal efficiencies at
selected sites are listed on Table 17.
Removals of BOD are high but not as high as removals of
suspended solids. The lower percentage removals of BOD for
infiltration-percolation as compared to irrigation also re-
flect the higher quality of effluent applied to the land.
For example, the effluent at Whittier Narrows averaged
5 mg/L of BOD. Other organics, such as detergents, are
reduced by 90 percent [69] .
At Flushing Meadows nitrogen removals were as high as 80
percent after the high nitrate peak was flushed into the
groundwater. This high removal is mainly the result of
biological denitrification. At Whittier Narrows, however,
the short frequent loading leads to excellent nitrification
but essentially no denitrification and therefore no nitrogen
removal.
Because infiltration-percolation system soils are not fine
textured, there is less opportunity for removal of phos-
phorus and metals by adsorption. Nevertheless, phosphorus
retention in sandy soils is significant. Only at Lake
George, New York, where the system has been operating
for 37 years, are there signs of phosphorus saturation of
part of the available soil volume [6].
Generally, enteric coliforms and viruses are almost com-
pletely removed [16, 41, 77, 100]. The major exception
is at Whittier Narrows, where coliforms tend to regrow
in the soil. Extensive testing has shown sizable
85
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PONDED WATER
1-1/2 IN. PIPE
CONNECTING PAN '
TO CENTRAL WELL '
' SAMPLE BOTTLED
3ROUND SURFACE
.:""/:". "'. ' 'SATURATED 20NE ' '
2-FT DIAM. 14-GAGE SHEET
METAL SAMPLING PAN. 9 IN.DEEP.
PACKED WITH SAND AND GRAVEL
CENTRAL WELL 4-FT DIAM
CORRUGATED METAL PIPE
WATER TABLE
SCHEMATIC CROSS SECTION
LEVEE ON FOUR SIDES
OF BASIN
WALKWAY
CENTRAL WELL
SAMPLING PAN
PLAN VIEW
FIGURE 8
SCHEMATIC OF SAMPLING PAN WELL
AT WHITTIER NARROWS, CALIFORNIA [69]
86
-------
FLEXIBLE VACUUM TUBING
SAMPLE COLLECTION
BOTTLE
EVACUATED
CONTA INER
APPROXIMATELY II 2 IN.
OUTSIDE DIAM THICK
WALLED PLASTIC PIPE
POROUS CUP
FIGURE 9
SUCTION PROBE FOR SOIL WATER SAMPLING
87
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Table 17. Removal Efficiency at
Selected Infiltration-Percolation Sites
Location
Flushing Meadows,
Arizona
Hyperion,
California
Lake George,
New York
Santeu ,
California
Westby, Wisconsin
Whittier Narrows,
Depth
ft
30
7
10
2003
3
8
RemoVal efficiency, 1
BOD SS N
98 100 30-80
90
96 100 43-51
88 -- 50
88 -- 70
- - Ob
P E. Coli
60-70 100
98
8-61 99.3
93 99
93
96 Oc
Reference
15
58
6
77
10
69
California
a. Lateral flow.
b. Short frequent loading promotes nitrification but not denitrification.
c. Coliforms regrow in the soil.
concentrations of coliforms at the 8-foot depth, but an
almost complete absence of fecal coliforms [69] . Virus
testing at Whittier Narrows in February 1963 showed 250
units of enteric virus per liter in the effluent, but
no measurable concentration in the percolate at the 2-foot
depth. More extensive tests at Santee have yielded the
same results [77].
ENVIRONMENTAL EFFECTS
The main effects of infiltration-percolation systems are on
the groundwater, soil, and vegetation. The effects on air,
surface water, and wildlife are generally negligible.
Groundwater
Groundwater is affected in terms of quantity and quality.
Groundwater recharge must either reverse or slow the drop
in the groundwater levels, or it must repel the intrusion
of salt water into fresh water aquifers. The latter is the
case at Hemet and Whittier Narrows, California, where the
intruding sea water has been repelled by recharge. At
Whittier Narrows and the nearby Rio Hondo spreading basins,
88
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Colorado River water and storm water have been spread along
with secondary effluent.
The effects on groundwater quality are mainly due to nitro-
gen, phosphorus, organics, toxic elements, and IDS. The
movement and effects of pathogens in groundwater will be
discussed under "Public Health Considerations."
Nitrogen Nitrogen in the form of nitrates is passed into
thegroundwater in significant quantities at nearly every
infiltration-percolation site. The only systems where sig-
nificant removals occur are Flushing Meadows and Westby,
Wisconsin. Both operated with long flooding and drying
periods which promoted denitrification. The effects of
nitrates on eutrophication and public health have been dis-
cussed in Section IV.
Phosphorus Because of the use of granular soils, the re-
moval of phosphorus may be limited. Phosphorus reaching
the groundwater may be a problem if the recovered water
is used in recreational lakes such as at Santee, or if
the recharged water reaches a surface body'of water such
as at Lake George. The problem is the increased eutrophi-
cation of the water bodies.
Organics If organic matter, particularly refractory
organic matter, reaches the groundwater, it may pose a
health hazard when the water is recovered for reuse. At
present existing installations there is evidence that little
organic matter reaches the groundwater [69,100]. The effects
of refractory organics in groundwater is a subject currently
requiring further research. Degradable organics can also
impart taste and odor to groundwater and deplete the
dissolved oxygen.
Trace Elements Trace element retention in soils of
infiltration-percolation may be limited because of the
granular nature of the soil. The buildup of organic humus
in the soil will tend to offset this deficiency, however,
and long term retention may occur. After passage through
30 feet of soil at Flushing Meadows, the renovated water
contained 2 to 2.5 mg/L of fluoride, 0.2 mg/L copper, 0.1
mg/L zinc., 0.07 mg/L lead, and 0.007 mg/L cadmium [15].
These concentrations represent only slight reductions (about
10 percent), in most cases, from the concentrations in
the applied effluent.
Total Dissolved Solids - The public health aspects of TDS
buildup have been discussed in Section IV. Although rapid
infiltration of wastewater minimizes salinity increases due
to evaporation losses, the continuous recycle of water
89
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through consumptive use, recharge, and reuse, will lead
to an increase in TDS. In relatively small, closed hydro-
logic basins this will occur more rapidly than in uncon-
fined basins. For example, at Santee, California, where
annual evaporation is far greater than rainfall, it may
be necessary to demineralize a portion of the water as
it passes through the reuse cycle.
Soil and Vegetation
The effects of land application of wasteivater on soil and
vegetation have been detailed in Section IV. The major
effect of infiltration-percolation on vegetation which dif-
fers from the effects already discussed, is that of
overwatering. At Westby, Wisconsin, the Reed canary grass
planted in 1971 and 1972 did not grow because excess waste-
water had to be applied to the basins. At Detroit Lakes,
Minnesota, as mentioned previously, and at Seabrook Farms
(see Section VI), the native trees were killed by the heavy
applications of water [57].
PUBLIC HEALTH CONSIDERATIONS
State regulations may have an effect on infiltration-
percolation systems. Other public health considerations
involve the movement of bacteria and viruses, movement of
toxic compounds, and insect and rodent problems.
State Regulations
Regulations concerning infiltration-percolation systems
deal mainly with control of groundwater quality. Proof, in
the form of monitoring data, that the groundwater is not
being polluted is often required. At Vineland, New Jersey,
primary effluent is applied to sandy soil without under-
drains, and no monitoring of groundwater quality is
practiced. To meet new state and federal regulations, sec-
ondary treatment is being designated prior to land
application. The Landis Sewerage Authority (Vineland)
has resolved to reduce organic and nitrogen loadings so
that groundwater withdrawn 500 feet away in any direction
from the site will meet New Jersey potable water standards.
Pretreatment of industrial-commercial wastes will be re-
quired by the Authority to eliminate all toxic substances
and reduce nitrate nitrogen to a maximum of 10 mg/L.
Although practical considerations, such as clogging, neces-
sitate pretreatment at least to primary effluent, few
regulations require pretreatment levels. At Nantucket,
Massachusetts, as discovered in the APWA survey,
90
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infiltration-percolation is practiced with untreated
wastewater.
Movement of Bacteria and Viruses
The spread of pathogens is of concern because of the possi-
bility of disease transmission. Bacteria and viruses can
be spread by insects or by the percolating water. At
Flushing Meadows, mosquitoes are not a problem despite the
20-day inundation period.
The movement of bacteria and viruses with the percolating
water is not likely to cause a threat to health. Numerous
studies at existing sites and in laboratory experiments in-
dicate that most bacteria and viruses are removed after
passage through a few feet of soil [15, 28, 33, 41, 53,
54, 55, 69, 138]. At Santee , California, viruses
injected into the percolating water were completely removed
in 200 feet of horizontal and vertical travel [77].
Movement of Toxic Compounds
Toxic compounds are generally more difficult to remove by
infiltration-percolation than are bacteria. Studies have
indicated that chemicals travel 2 to 30 times as far through
soil as bacteria [104]. Examples of both chemical and bac-
terial travel through soil and groundwater are listed in
Table 18. Where known toxicants are present in wastewater
applied to the land, an intensive monitoring and control
program should be maintained to preclude contamination of
the groundwater.
SYSTEM FAILURES
An infiltration-percolation site can be abandoned for any
number of reasons, ranging from public complaints to degra-
dation of the groundwater supply. The reasons that are
discussed here are overloading and groundwater degradation,
Limits of Loading
Systems can be overloaded by liquids, organics, or
nutrients. Any of these forms can saturate a soil and
sharply reduce its usefulness as a treatment and disposal
medium.
Liquid Loading When a soil becomes saturated with waste-
water, anaerobic conditions will soon prevail, and the soil
will become sealed. Without an adequate drying period,
aerobic conditions will not return and the system will fail.
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Table 18. Summary of Distances of Travel of Pollution
in Soil and Groundwater [104]
Nature of pollution
Sewage polluted trenches
intersecting groundwater
Polluted trenches
intersecting groundwater
River water in
abandoned wells
Sewage in bored latrines
intersecting groundwater
Sewage in bored latrines
lined with fine soil
Sewage in bored latrines
intersecting groundwater
Observed distance Time of
Pollutant of travel3 travel
Coliform bacteria
Chemicals
Coliform bacteria
Uranin
Intest. pathogens
Tracer salts
Coliforra bacteria
Anaerobic bacteria
Chemicals
Coliform bacteria
Coliform bacteria
Chemicals
65 ft
115 ft
232 ft
450 ft
800 ft
800 ft
10 ft
SO ft
300 ft
10 ft
35 ft
90 ft
27 wk
17 hr
17 hr
Sewage in bored latrines
intersecting groundwater
Coliforra organisms
introduced into soil
Coliform bacteria 80 ft; regressed
to 20 ft
Coliform bacteria
50 m
37 days
Sewage effluents on
percolation beds
Sewage effluents on
percolation beds
Sewage polluted
groundwater
Introduced bacteria
Chlorinated sewage
Industrial wastes
Industrial wastes
Industrial wastes in
cooling ponds
Chemical wastes
Industrial wastes
Weed killer wastes
Coliform bacteria
Ammonia
Bacteria
Bacteria
Bacillus
prodigiosus
Phenols, fungi
Dye
Tar residues
Picric acid
Picric acid
Mn, Fe, hardness
Miscellaneous
chemicals
Chromatc
Phenol
Phenol
Chemical
400 ft
1.400 ft
150 ft
a few meters
69 ft
300 ft
300 ft
197 ft
several miles
3 mi
2,000 ft
3-5 mi
1,000 ft
1,800 ft
ISO ft
20 mi
9 days
24 hr
4-6 yr
3 yr
6 mo
a. For bacteria, the distance observed was the extent of travel; for
some chemicals the observations were taken along paths of unknown
extent.
92
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An example is Westby, Wisconsin, where the infiltration
beds have become holding ponds.
Organic Loading - As stated in the previous section, the
organic loading limit of 30 tons/acre/yr will not usually
be reached except in the disposal of sludge. At Marysville,
California, the percolation ponds were plugging too rapidly,
so the pretreatment was increased from primary to secondary.
This is a case of management recognizing an overloading
condition and taking necessary corrective action.
Nutrient Loading. There are no known systems that have
failed solely because of nitrogen. The South Lake Tahoe
system was removing only 50 percent of the influent nitro-
gen which contributed to its abandonment [36] . Systems
such as Whittier Narrows have not been abandoned despite
the fact that the nitrogen applied is not removed, merely
changed to the nitrate form.
Infiltration-percolation systems tend to have limited ex-
change capacities for removal of phosphorus. At Lake
George, New York, some percolation beds appear to be satu-
rated with phosphorus because little renovation is occur-
ring at the 10-foot depth [6].
Groundwater Degradation
Groundwater degradation is closely tied to overloading and
mismanagement. Extensive monitoring and control practices
should be maintained to forecast and prevent degradation
from occurring. Because infiltration-percolation will cer-
tainly affect the groundwater to some extent, it is impor-
tant to manage the groundwater and maintain control of its
movement.
93
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SECTION VI
LAND APPLICATION OF INDUSTRIAL WASTEWATER
BACKGROUND
Application of industrial wastewater to the land for treat-
ment and disposal has been a relatively recent development
in the history of land application of wastewaters. Reports
of land application operations specifically for industrial
wastes did not appear in the literature until the 1940s
[61]. Since that time, however, there has been a dramatic
increase in the number of industrial wastewater land appli-
cation sites. A 1965 survey indicated that over one-third
of all land application sites in the United States were
serving the food processing industry alone [9].
Several factors are responsible for the increased interest.
The principal driving force is the intensified effort
to reduce pollutional loads on the nation's surface waters.
Land application of wastewaters is a means by which discharge
to surface waters can be eliminated, and it has also proven
to be an economic alternative to conventional treatment
methods at several sites where effluent is discharged.
Most land treatment and disposal techniques avoid the
problems of system startup associated with conventional
treatment facilities used for seasonal industries.
Extensive use of land application has been restricted pri-
marily to three industries--namely, the food processing
industry, which accounts for the majority of applications;
the pulp and paper industry; and the dairy industry. Two
reasons for the development of land wastewater application
in these industries are: (1) the location of process
operations in rural areas with close access to suitable
land, and (2) the nature of their wastewaters, which are
generally nontoxic and easily biodegradable.
The methods of land application described earlier for munic-
ipal wastewater are applicable to industrial wastewaters;
however, the systems must be designed and operated to
94
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account for the differences in wastewater characteristics.
The purpose of this section is to discuss those considera-
tions which must be given to the design and operation of
land treatment and disposal systems receiving industrial
wastewaters.
WASTEWATER QUALITY AND PRETREATMENT REQUIREMENTS
Consideration must first be given to the quality of the
wastewater to be applied to the land. This requires a com-
plete characterization of the wastewater with regard to
constituents that may affect or interact with the soil or
groundwater. The presence of constituents which may ad-
versely and irreversibly affect the soil and groundwater
environment can preclude the use of a land application
system unless they can be economically removed from the
wastewater prior to application. Pretreatment may
also be required to remove constituents that impair the
efficient operation of the system, but are not necessarily
damaging to the terrain ecosystem.
Wastewater Characteristics
Industrial wastewaters contain many of the constituents
found in municipal wastewaters as described in Section IV.
The characteristics of industrial wastewaters vary widely
not only by industry but also by product. Moreover, even
when plants are similar, their wastewater characteristics
may vary according to the processing technique used. Con-
sequently, there is no such thing as a typical industrial
wastewater unless the various processes generating the
wastewater are well defined. There is no attempt in this
report to typify the myriad industrial wastewaters. Rather,
those wastewater constituents that should be considered in
connection with land application systems are identified,
and their potential impact is discussed. The more impor-
tant constituents are listed in Table 19 along with ranges
or upper limits of concentrations which have been success-
fully applied to the land as reported in the literature.
This list is not intended to be exhaustive, but it illus-
trates the types of industrial wastewaters that are amenable
to land application. Important characteristics are BOD and
COD, suspended solids, total fixed dissolved solids, nitro-
gen, pH, temperature, color, heavy metals, and the SAR.
BOD and COD - The COD is a measure of the total organic con-
tent of a waste, while the BOD indicates what portion of
those organics are biodegradable in a specified period of
time. The ratio between COD and BOD is therefore a useful
parameter in determining the degradability of a wastewater.
Easily degradable wastewaters, such as those from the
95
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Table 19. Characteristics of Various
Industrial Wastewaters Applied to the Land
Food
Constituent processing Pulp and paper Dairy
BOD, rag/L 200-4,000 60-50,000 4,000
COD, ms/L 300-10,000
Suspended solids, mg/L 200-3,000 200-100,000
Total fixed
dissolved solids, mg/L 1,800 2,000 1,500
Total nitrogen, mg/L 10-50 -- 90-410
PH 4.0-12 6-11 5-7
Temperature, deg F 145 195
industries listed in Table 19, are well suited to land
application because the soil mantle is a highly efficient
biological treatment system. There are limits, of course,
to the amount of degradable material that can be placed
on the land without stressing the terrain ecosystem.
Permissible organic loading rates will be discussed later
in this section. Organics in the form of sugars are more
readily degradable than starchy or fibrous material.
Consequently, those wastewaters which contain predominantly
sugars, such as food processing wastes, may be applied
at a generally higher organic rate than wastewaters from
the pulp and paper industry which often contain starchy
or fibrous material. Industrial wastewaters containing
significant concentrations of nondegradable or resistant
organics in solution are generally not suitable for land
application, because these materials can cause severe
soil clogging." Also, they are likely to enter the ground-
water and impart undesirable tastes and odors.
Suspended Solids Suspended solids may include coarse
solids,such as peelings and chips, or fine solids, such as
silt and small organic particles. Cannery wastewaters often
contain large amounts of silt which is washed off fruits and
vegetables. The presence of high concentrations of solids
in a wastewater does not restrict its application to a land
treatment system because solids can normally be separated
96
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quite simply by pretreatment. Failure to provide adequate
solids removal, however, can impair the operation of the
system by clogging of the soil or sprinkler nozzles.
Total Fixed Dissolved Solids The importance of the mineral
content of a wastewater applied to the land has been dis-
cussed in detail in Sections IV and V. The major problem
associated with dissolved solids is that the soil mantle
does not provide mechanisms to remove them permanently from
solution. Consequently, mineral salts either build up
their concentration in the soil solution or are leached to
the groundwater. Industrial wastewaters with very high
total fixed dissolved solids are therefore not generally
suitable for land application unless special provisions are
made to collect soil drainage.
Nitrogen The nitrogen content of many industrial ivaste-
waters is usually of less concern than that in municipal
wastewaters. The reason is that the carbon to nitrogen
ratios found in most industrial wastewaters permit a larger
portion of nitrogen to be removed by bacterial assimilation
and incorporation into cellular material. Notable excep-
tions are feed-lot, dairy, and meat packing wastes. The
latter have been found to contribute a significant nitrate
load to groundwaters [50].
pji The pH of industrial wastewaters varies over a wide
range, even in the wastewater from one plant. This is
especially true of cannery wastewaters that include wash-
water from lye peeling operations. Waters having a pH be-
tween 6.5 and 9.5 are generally suitable for application to
most crops and soils [12]. Wastewaters with a pH below
6.5 have been successfully applied to soils that have a
large buffering capacity. However, wastewaters having ex-
cessive acidity or hydroxide alkalinity must normally be
neutralized to be suitable for land application.
Temperature The high temperatures of some industrial
wastewaters, such as spent cooking liquors from pulping
operations, can sterilize the soil, thus precluding the
growth of vegetation and reducing the renovative capacity
of the soil mantle [43] . High temperature wastewaters
should, therefore, be cooled prior to land application.
Color - The color in most industrial wastewaters is associ-
ated with degradable organic material and is effectively
removed as the wastewater percolates through the soil
mantle. However, some wastewaters--for example, spent
sulfite liquor--contain colors associated with relatively
inert components such as lignins. It has been observed
that this color is not only transmitted through the soil
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but also intensified by the formation of organic complexes
[12]. Groundwater contamination with this type of waste-
water is difficult to avoid. This fact must be considered
carefully when evaluating land application of such
wastewaters.
Heavy Metals Industrial wastewaters containing signifi-
cant concentrations of heavy metals generally are not
suitable for application to most soils. However, success-
ful operations with such wastewaters have been reported. A
paper processing plant in Vicksburg, Michigan, applies high
concentrations of lead, vanadium, and cadmium to a peat-type
soil. The high organic content of the soil provides a
large heavy metal retention capacity, although this capacity
is expected to be exhausted within 20 years. For such
wastewaters the response of the soil at a proposed site to
the wastewater to be applied should be studied carefully
prior to full-scale operation.
Sodium Adsorption Ratio It is preferable that the SAR
(defined in Section III) of wastewaters applied to the land
be less than 8 to prevent deflocculation of clay soils.
This property is less critical with sandy soils. Industrial
wastewaters with extremely high SAR's must be applied
using special soil management procedures to compensate
for the effect of the sodium. A pulping operation in
Terre Haute, Indiana, applies 0.2-mgd sodium base cooking
liquor containing 16.4 percent sodium (percent of dry
solids) to a land disposal site, but once the soil structure
is destroyed, the site must be rested for several years,
and a source of calcium must be added to the soil to replace
the sodium [43].
Pretreatment Requirements
In contrast to municipalities, industry has viewed land
application more as an alternative to conventional treat-
ment methods than as an advanced stage of treatment.
Consequently, industrial systems rely more on the renova-
tive capacity of the soil mantle, and pretreatment is
generally minimized. Pretreatment is required in most
cases to eliminate frequent operating difficulties and, in
some cases, to avoid adverse effects on the terrain
environment.
Screening Screening with rotary or vibrating screens has
been almost universally employed as a form of pretreatment
to separate coarse solids from industrial wastewaters.
Coarse solids can cause serious problems with distribution
of the wastewater, particularly if spraying is used. Fine
screens at pump inlets or in-line screens in the discharge
98
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piping may also be employed as an added precaution against
spray nozzle clogging. Experimental work has been conducted
on pea processing wastewater to determine the feasibility
of comminuting solids and including them in wastewater
applied to the land by sprinklers [20]. The study indi-
cated that this approach did not adversely affect the soil
or vegetation; however, insufficient disintegration of fi-
brous solids by comminutors resulted in sprinkler clogging
problems. Use of this system on other types of wastewaters
must be evaluated for the wastewater in question.
Lagooning The use of lagoons or settling ponds prior to
land application of industrial wastewaters has been
prevalent. Such lagoons serve to remove silt and other
suspended particles which may contribute to clogging of the
distribution system as well as hasten the clogging of soil
pore space. The BOD of the wastewater can be reduced sub-
stantially in lagoons depending on the detention times.
Lagoons also serve to equalize wastewater flows and strength
and thereby provide more flexibility to the operation of the
system and prevent shockloading. Lagoons,, however, are not
without their problems. The generation of odors resulting
from anaerobic conditions is the principal drawback re-
ported in the literature. Odors reached objectionable
levels at several systems that sprayed lagooned wastewater
[27]. The odor problem was eliminated by bypassing the
lagoon and spraying fresh wastewater. Odor control by the
addition of sodium nitrate to eliminate anaerobic condi-
tions is possible but not always practical because of
dosage requirements. Additionally lagoons must be con-
stantly maintained to prevent propagation of insects,
and accumulated solids must be removed periodically.
At many industrial sites, lagoons were not designed as part
of the land application system but were remnants of previ-
ous treatment facilities included in the new system. The
decision to provide lagooning prior to land application
should be based on considerations of odor production poten-
tial, desirability of equalization, the effect of solids on
the application system, and economics.
pH Adjustment Industrial wastewaters with sustained flows
outside the pH range of 6 to 9.5 should be neutralized prior
to land application if the site is to be vegetated. Waste-
waters with widely fluctuating flows can be self-
neutralizing if an equalization basin is provided prior to
land application. In other cases a continuous pH control
system may be necessary. This type of pH control may be
accomplished in a pipeline or in neutralization basins.
99
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The use of neutralization basins is normally preferred be-
cause less sophisticated equipment is required to obtain
adequate control.
Cooling For wastewaters below 150 deg F, application by
sprinkling normally provides sufficient cooling to protect
vegetation and soil. Such cooling may be enhanced by the
use of sprinklers that produce small spray droplets or that
have large spray diameters. Wastewaters with temperatures
much above 150 deg F generally should be cooled prior to
spraying if vegetation is desired.
TREATMENT BY OVERLAND FLOW
Treatment of wastewater by overland flow consists of the
filtering action of vegetation as the wastewater flows over
the sloped land surface. Bacteria present on the grass and
vegetative litter act to decompose the solids and organics.
The process has been well developed in this country for
treatment of food processing wastewaters.
The overland flow method was developed to take advantage of
the low permeability properties of heavy soils. The prop-:
erties of clay soils are discussed under "Soil
Characteristics" in Section IV. The technique was pioneered
in this country at the Campbell Soup Company plant at
Napoleon, Ohio, in 1954 [109]. It was discovered that run-
off from spray application traveling down the relatively
steep slopes was receiving a high degree of treatment.
This principle of grass filtration has been refined through
experience at several other overland flow or spray-runoff
installations.
Overland flow differs from spray irrigation primarily in
that a substantial portion of the wastewater applied is de-
signed to run off and must be collected and discharged to
receiving waters, or in certain cases where wastewater is
produced only during part of the year, stored for deferred
application. An overland flow system, therefore, functions
more as a land treatment system than a land disposal system.
The design and operation of overland flow systems are dis-
cussed in the following paragraphs.
System Design
The design of an overland flow system entails; (1) selec-
tion of a site with proper conditions of soil type, topog-
raphy, and climate; (2) determination of the land area
required to accept the wastewater; (3) selection of a suit-
able cover crop; and (4) layout of the distribution and
collection system.
100
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Site Conditions and Land Preparation The most important
criterion to be"used in selecting a site for overland flow
is the structure of the soil. Soils with minimal infiltra-
tion capacity, such as heavy clays or clay loams, are re-
quired for this technique to be effective. Soils with good
drainage characteristics are better suited to irrigation or
infiltration-percolation techniques.
A sloping terrain is necessary to allow the applied waste-
water to flow slowly over the soil surface to the runoff
collection system. The slopes must be steep enough to pre-
vent ponding of the runoff, yet mild enough to prevent
erosion and provide sufficient detention time for the waste-
water on the slopes. Experimental work at Paris, Texas,
has indicated that best results are obtained with slopes
between 2 and 6 percent [24] . Slopes must be uniform in
cross slope and free from gullies to prevent erosion and
allow uniform flow over the slopes.
A slope length of 175 feet was found at Paris, Texas, to
provide a sufficient detention time to achieve effective
treatment of the wastewater. The wastewater at the Paris
facilities is a highly degradable food processing waste-
water with an average BOD concentration of 500 mg/L.
Longer slopes may be necessary for higher strength or less
easily degradable wastewaters or for colder climates. This
would have to be evaluated for the individual wastewater
and location.
The network of slopes and terraces that make up an overland
flow system may be adapted to natural rolling terrain, as
has been done at Napoleon, Ohio [9]. The use of this
type of terrain will minimize land preparation costs. The
overland flow system has been adapted to severely eroded
land at Paris, Texas, and to relatively flat land at Davis,
California, by substantially reshaping the terrain. Where
such reshaping is required, the finished grading must be
done to close tolerances to prevent erosion. Care must
also be taken to reestablish topsoil on the constructed
slopes to provide an adequate seed bed for the cover crop.
The system at Davis, California, consists of a series of
slopes and terraces constructed in a sawtooth pattern [85].
Experience with this system indicates that an undular pat-
tern of opposite facing slopes with collection ditches be-
tween would provide greater operating flexibility under
changing wind conditions.
The overland flow system may be adapted to almost any cli-
mate, although a warm semiarid climate is preferable. There
are no systems identified in this study that operate under
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prolonged freezing conditions. This is an area that requires
further field research.
If it is not possible to reuse the runoff from the overland
flow system, then a waterway or drainage system must be in
the vicinity to transport the effluent from the site.
Requirements set by state agencies for discharge into re-
ceiving waters are often quite stringent, and the treatment
efficiency of the overland flow system must be sufficient
to meet any such requirements.
Since infiltration into the soil is minimal in overland
flow, the effects of the system on groundwater and, con-
versely, the effects of groundwater on the system are not
as critical as with other application methods. The depth
of groundwater below the soil surface is the point of major
concern. This depth must be sufficient so as not to affect
the growth of the cover crop. This condition is discussed
in Section IV.
Loading Rates The area of land selected for an overland
flow system will set the overall loading rates on the sys-
tem with regard to wastewater volume, organic material,
solids, and nutrients. Loading rates differ from applica-
tion rates or application frequency in that they refer to
the long term average conditions for the entire site, while
the others refer to short term operating conditions.
Application rates and frequency are discussed under system
operations.
Liquid loading rates are normally reported in units of gal-
lons per acre per day or inches per day and are calculated
by dividing the field area of the site by the average
daily wastewater flow. The field area is the acreage of
the terraced treatment system. The term "wetted" acres
refers to the area covered by the spray diameters and is
less than the "field" acres. The liquid loading rates
used during peak production periods at existing overland
flow facilities are listed in Table 20 along with the aver-
age daily flow rates. Loadings will vary with the produc-
tion of wastewater at the processing plant. Those shown in
Table 20 are for peak season conditions.
Organic and suspended solids loadings are also indicated in
Table 20. These are based on the average BOD and suspended
solids concentration of the applied wastewater. Although
all of the systems to date have been designed using hy-
draulic loading as the primary sizing criterion, there has
been no information reported correlating the BOD loading
with treatment efficiency. For higher strength wastewaters
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Table 20. Peak Season Loading
Rates of Overland Flow Treatment Systems
Suspended
Liquid solids
Average Field loading Organic loading loading
flow, area, rate, rate, rate,
Site location mgd acres in./day Ib BOD/acre/day Ib/acre/day
Napoleon, Ohio
Paris ,
Texas
Chestertown, Maryland
Davis ,
California
4
3
0
3
.oa
.5b
.7b
.25°
335
385
70
250
0.
0.
0.
0.
45
35
4
5
40
37
67
100
36
IS
29
56
a. 10-month operating season.
b. Year-round operation.
c. 3-month operation season.
this parameter may well govern.
ther research is necessary.
This is an area where fur-
Nutrient loading rates were not used as a design parameter
for the current systems. However, nutrients undoubtedly
are important to the performance of a system, since over-
land flow is essentially a biological treatment system.
Further study is therefore warranted to determine the
effects of nutrient loading on system performance.
Cover Crop Selection The cover crop is one of the essen-
tial components of an overland flow system. It acts to
prevent soil erosion, provides removal of nutrients through
uptake, and, most importantly, serves as media for the
microbial population whose metabolic activity provides the
wastewater treatment. The grass serves in a manner similar
to rock or plastic media in a conventional trickling filter
Thus, overland flow has also been referred to as grass
filtration. In addition, when the crop is harvested, it
may be removed and sold for cattle feed.
Perennial grasses with long growing seasons, high moisture
resistance (hydrophytic), and extensive root formation are
best suited to the application. Comparative field studies
at Paris, Texas, indicated that Reed canary grass was the
superior grass at that location. It demonstrated a very
high nutrient uptake capacity and yielded a high quality
103
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hay upon harvest [24]. Hauling the crop away during har-
vest provides positive removal of the nutrients taken up
during plant growth. The amounts of nutrients taken up by
crops are listed in Tables 5 and 11 in Section IV.
Tall fescue has also been used as a cover crop and, under
laboratory conditions, was found to be superior to Reed
canary grass [12]. However, the Paris field studies indi-
cated that the semidormant behavior of tall fescue after
harvest allowed the intrusion of undesirable native grasses.
Reed canary grass is a slow starting grass and therefore
should be planted with a nurse crop, such as rye grass or
tall fescue. The experience at Paris, Texas, with tall
fescue indicates that rye grass would be a better selection,
However, moderate irrigation of the system would be re-
quired until the Reed canary was established because the
rye grass has a lower moisture resistance.
The suitability of Reed canary grass under various climatic
conditions has yet to be established. The crop selection
for the facility at Davis, California, was made with this
in mind. A combination of Reed canary, fescue, trefoil,
and Italian rye grass was planted. Reed canary has emerged
but after 2 seasons has yet to become the dominant species.
Further study is warranted to determine the best cover
crop for the overland flow process under various climatic
conditions. Other species, such as bermuda grass, may
also be suitable.
Distribution and Collection System Distribution of the
wasTewater in an overland flow system is accomplished by
sprinklers. Spraying is necessary to distribute the or-
ganic and solids load over a wide area to avoid over-
stressing any one portion of the system. The discussion
presented in Section IV on the design of sprinkler instal-
lations also applies to overland flow systems. However,
there are some particular considerations which must be
given to the design of an overland flow sprinkler system.
The principle of overland flow requires the wastewater to
be distributed along the top of a slope and allowed to flow
down to the collection system. Sprinklers are therefore
placed so their spray diameter covers approximately the
upper one-third to two-thirds of the slope. The sprinkler
setting must allow for overlap to provide efficient area
coverage. More overlap is necessary where high winds
are expected. As an example, the system at Davis,
California, was designed with a sprinkler spacing of 100
feet, a sprinkler discharge of 25 gpm at 60 psi, and a
104
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spray diameter of 150 feet. The sprinklers were placed
65 feet from the top of each slope.
Buried, permanently set sprinkler systems have been found
preferable to portable aluminum systems. The major cost
advantage in portable systems is lost when used for over-
land flow because the short cycle periods make hand moiling
of laterals impractical. In addition, experience at Paris,
Texas, with portable systems has shown that leakage from
high pressure portable mains can result in severe erosion
of the slopes. Portable laterals also pose a barrier to
the downslope runoff, which can adversely effect distribu-
tion and cause ponding on the slopes.
Individual sprinkler risers should be provided with iso-
lating valves to allow malfunctioning sprinklers to be shut
off under pressure. This provision will protect the slope
from erosion caused by heavy streams of water which may
occur during breakdown. Lateral lines should be provided
with cleanouts to allow removal of solids that may build
up in the line.
Automatic or centralized remote controls are recommended
for systems to reduce the risk of human error and manpower
requirements. Such controls have proven reliable and
will generally result in lower operating costs. The pneu-
matic controls employed at existing installations have
provided the systems with excellent operating flexibility.
A network of ditches must be constructed to intercept the
runoff and channel it to the point of discharge or storage.
The interception ditches are normally not lined. They must
be graded to prevent erosion, yet, at the same time, they
must have sufficient slope to prevent ponding in low spots.
The collection system must be designed to accept the added
flow from rainfall runoff. This is particularly important
if the effluent is to be pumped.
For some summer seasonal operations it may be possible to
store runoff from the system and reuse it in the following
spring to meet the irrigation demands of the cover crop.
Provision would have to be made for handling storm water
runoff in excess of storage capacity.
Operation and Management
As with any land application process, conscientious manage-
ment is critical .for effective performance. Ideally a
system should be operated by personnel with agricultural
experience, although this is not essential. A well de-
signed system should perform properly if it is not
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neglected. The major tasks involved in operating an over-
land flow system include (1) maintaining the proper appli-
cation rate and application frequency or hydraulic loading
cycle, (2) managing the soil and cover crop, and (3) moni-
toring the performance of the system.
Hydraulic Loading Cycle Cycling of the wastewater appli-
cation must be programmed to keep the microorganisms on the
soil surface active. Once again, the principle is similar
to a conventional trickling filter with intermittent dosing
The application period should be controlled 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 exist-
ing systems indicates that optimum cycles range from 6 to
8 hours on and 6 to 18 hours off, depending on the time of
the year. Application periods may be extended during the
summer months to allow portions of the system to be taken
out of service for crop harvesting. Application rates or
discharge rates are normally held constant and are deter-
mined by the sprinkler selection. The rates on existing
systems surveyed range from 0.05 in./hr to 0.1 in./hr,
using sprinklers with a discharge of 15 to 30 gpm.
Cover Crop and Soil iManagement Just as equipment in con-
ventional treatment facilities must be maintained, the
cover crop and soil in overland flow systems must receive
attention in the form of soil amendments, fertilization,
pest control, and harvesting. The most important of these
tasks is harvesting. Removal of the crop is necessary to
realize the removal of the nutrients and minerals which
have been taken up by the plants and to renew the plants'
capacity to accomplish this uptake as well as 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. Experimental work conducted at Paris,
Texas, indicated that it is possible to predict the time of
year and stage of growth when hay of the highest value can
be harvested [38, 24]. This is important in order to
maximize crop value and nutrient removal capacity. In
addition, it was found that a late fall harvesting not only
resulted in a crop of less nutritional value, but also had
adverse effects on the uptake capacities the folloxving
spring. This is an important consideration for year-round
operations. Overharvesting can also reduce the removal
potential of the cover crop. Further study is necessary
to better define the effects of harvesting on performance.
-------
Consultation with local farm advisers or agricultural ex-
tension service representatives can be helpful in planning
a harvesting schedule. As mentioned previously, wastewater
application schedules must be adjusted to permit harvesting.
Scheduling of harvest can be complicated by rainfall in
areas of the country that receive year-round precipitation.
Harvesting must be done with care. The field must be
allowed to dry sufficiently to prevent damage to the slope
by harvesting equipment. Use of equipment with high flota-
tion tires is helpful in this regard.
The use of soil amendments or fertilizers has not been nec-
essary for the existing overland flow systems which are all
treating cannery wastewaters. Application of the method to
other types of wastewaters, which may be nutrient deficient,
may require the periodic application of agricultural fer-
tilizers to meet the needs of plants as well as the micro-
organisms in the soil. Application of high sodium
wastewaters may necessitate the use of special management
techniques to reduce the sodium concentration in the soil.
Protection of the cover crop from insect or other pests may
require the use of pesticides. Experience at Paris, Texas,
indicated that application of insecticides to control
snails and army worms had no perceptible effect on the
microbial population in the soil or on the performance of
the system [38].
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. Parameters of interest have
been discussed earlier in this section under water quality
considerations. These will, of course, vary in importance
with the wastewater in question. If the runoff water is
being discharged into a receiving water, regulatory agencies
may require a specific monitoring program. Flow measurement
and sampling equipment should be an integral part of the
system design.
Monitoring of the groundwater is normally not required for
an overland flow system because infiltration is minimal.
The presence of a specific contaminant, however, may war-
rant such a monitoring program.
Treatment Efficiency The performance of existing systems
in terms of treatment efficiency has been impressive al-
though only cannery wastewaters have been treated thus far.
Effluent quality equals or exceeds that from conventional
tertiary treatment processes. Removal efficiencies for
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several pertinent parameters are shown for the existing
systems in Table 21. The facility at Paris, Texas, has
been studied extensively in comparison with the others. On
the other hand, the system at Davis, California, has com-
pleted its second season of operation and, although it is
functioning well, definitive data have not been developed
as yet.
The Paris studies confirmed that microorganisms normally
fo-und in the soil were responsible for oxidation of organic
material. They also revealed that the removal efficiency
did not decrease during the winter months. Decreased meta-
bolic activity was compensated for by an increase in micro-
bial population. In addition, it was found that drying of
the slopes reduced the microbial population and thus the
treatment efficiency, but recovery when spraying began
again was normally quite rapid.
A portion of the nutrients are removed from the wastewater
through luxury uptake by the cover crop and subsequent
harvesting. This was evidenced by a phosphorus and nitrogen
content in the harvested crop that was nearly double normal
values [24]. Plant uptake alone, however, does not account
for all the nitrogen removal, and volatilization and de-
nitrification are probably occurring to some extent. The
system also exhibited a large buffering capacity as in-
dicated by the range of pH values in Table 21.
Operational Problems Problems of existing installations
have been primarily mechanical in nature and have been
traced to design deficiencies. Some of the more notable
problems are described here.
Table 21. Removal Efficiencies on a
Concentration Basis for Overland Flow Facilities
BOB, tg/L Suspended solids ,»i/i '.utal nitrogen, «c/L Total phosphorus .aj/L pil (ranjcj
Site In- Ef- % In- EC- » In- Ef- I In- Ef- I In- tf-
location fluent fluent kcnoval fluent fluent Removal fluent fluent Reiuval fluent fluent Rcnovil fluent fluent
l*ar i 1,
T*«« 490 I 91 245 24 90 19.0 5.0 «5* 8.5 4.0 55* 5.1-9.3 6.J-8.0
N-ipcleon,
Chio 400 19 95 358 21 92
Chcitcrtown,
Maryland 100 S 99* 348 28 92
a. 90 percent renoval was reported on nass basis.
b. Up to 60 percent reaoval vas reported on a aass basis.
108
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At the Paris installation, numerous leaks developed in the
air tubing connecting the automatic valves with the control
panel. These leaks were difficult to locate because junc-
tions were not marked. This problem was avoided in later
installations by encasing all tube in conduits and locating
all tubing junctions within a junction box [38].
Experience with control valves at the Paris facility demon-
strated that butterfly valves did not seat tightly, result-
ing in continuous leakage from sprinkler heads. Inclusion
of a magnetic brake on electric motor operators will elimi-
nate this problem. The use of diaphragm valves in later
installations avoided this problem.
The major nonmechanical problem, as with most other agri-
cultural operations, has been the weather--specifically,
rainfall at harvest times. This is less of a problem in
areas such as California where the spring and summer are
essentially free of rain. At the Paris installation, how-
ever, rainfall has resulted in several late harvests, the
consequences of which were discussed previously.
LAND APPLICATION BY IRRIGATION AND INFILTRATION-PERCOLATION
Soils with fair to excellent drainage characteristics are
more suitable for irrigation or infiltration-percolation
than for overland flow. The distinction in loading rates
between irrigation and infiltration-percolation will not be
made here for industrial wastewaters. Current practice
with these two methods ranges from light loadings with irri-
gation specifically for crop production to heavy loadings
and the use of nonvegetated infiltration basins. Most sys-
tems operate well between these extremes, and the design
and operating aspects of the various systems do not differ
substantially.
System Design and Construction
There are no formulas by which a land application system
may be designed. Each design requires participation of an
engineer with extensive background knowledge of land appli-
cation systems, a soil scientist, and an agronomist. Other
specialists, such as hydrologists or geologists, may also
be necessary [65]. Consequently, the discussion here is
not aimed at establishing rigid standards, but rather at
presenting important factors and related experience in
design.
The major components of system design and construction in-
clude the following: (1) selection and preparation of a
109
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site with suitable drainage characteristics and sufficient
area to accept the wastewater; (2) selection of design load-
ing rates; (3) the design and installation of a wastewater
distribution system and, where applicable, an effluent col-
lection system; and (4) selection of suitable vegetative
cover if one is feasible.
Site Selection and Preparation - Four basic site conditions
must be considered when selecting an area for land applica-
tion of wastewaters by irrigation or infiltration-
percolation. These are: (1) the characteristics of the
soil; (2) the subsurface hydrologic and geologic conditions;
(3) the surface topography; and (4) the climate. The
effects of these conditions on design and operation of
municipal wastewater land application systems have been dis-
cussed in detail in Sections IV and V, and are equally valid
in the case of industrial wastewaters. Therefore, the dis-
cussion here will be limited to considerations which apply
specifically to industrial wastewaters.
As discussed in Section III, soils vary in their ability to
remove or retain certain wastewater constituents. The in-
dustrial wastewater applied to a given soil must be com-
patible with the renovative capabilities of the soil. For
instance, industrial wastewaters containing significant
refractory organic, heavy metal, nutrient, or color concen-
trations should be applied to soils with high adsorptive
capacities, such as loams, peats, or clay loams. Failure
to match the soil to the wastewater can result in ground-
water contamination, as has occurred at some installations
where spent sulfite liquor has been applied to the land
[12].
It has been demonstrated that removal of degradable organic
material by a land application system is essentially inde-
pendent of the soil type. Therefore, industrial wastewaters
that are free of nondegradable contaminants can be and have
been successfully applied to all soil types.
The use of underdrain systems to adapt to adverse subsur-
face geologic or hydrologic conditions, such as a high
groundwater table or impervious subsoils, has been common
for industrial systems. An example of the successful use
of underdrains is the irrigation facility for poultry
processing wastewater at Sumter, South Carolina (see
Appendix A). Perforated drainage pipe was installed to
allow utilization of the full depth of a highly permeable
sand layer which was underlain by a relatively impervious
sand-clay layer. Underdrainage also successfully solved
the problem of limited lateral movement of water underground
110
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due to high water tables at board mill installations at
L'Anse, Michigan, and Largo, Indiana.
Although underdrains may prove helpful in some cases, the
consequences of their use should be considered. Use of
underdrains will result in an effluent that must be col-
lected and discharged. In addition, their use may reduce
the removal efficiency of the system if sufficient deten-
tion time in the soil matrix is not provided.
Loading Rates The land required for a system is deter-
jiined from the flow rate of wastewater and the use of the
loading rate that requires the largest acreage. Controlling
loading rates may be (1) liquid or hydraulic, (2) organic,
or (3) nutrient or other inorganic chemical. Most systems,
according to reported information, are governed by the hy-
draulic loading rate, which is a direct function of the
soil drainability. The wide variation in hydraulic loading
rates used by current systems is illustrated in Table 22
for several selected installations. Operators of many in-
dustrial wastewater systems have determined the permissible
hydraulic loading of a site through a series of trial and
error stepwise expansions. From a planning standpoint this
is not a desirable method. Operation of test plots is the
preferred method of determining design loading rates although
it is time-consuming and costly to do so.
The soil mantle has a limited capacity to adsorb and stabi-
lize degradable organic material, without having detrimental
effects on the terrain ecosystem. When this capacity is
approached by the application of the wastewater, the organic
loading rate becomes the limiting design factor. In gen-
eral, organic loading will be limiting only for systems
handling very high BOD wastewaters (greater than 10,000
mg/L). Defining the limiting organic loading rate for a
system must be done on an individual basis. However, rule-
of-thumb rates which can serve as a design guide have been
developed. Extensive laboratory studies with various pulp
mill effluents on four representative soil types indicated
that a maximum BOD loading rate of 200 Ib/acre/day could be
used without detriment to vegetation or soil permeability,
and a high degree of treatment could still be maintained
[12]. There are, of course, substantially higher loading
rates being used with success at several installations, as
evidenced by some of the rates listed in Table 22. It
should be noted, however, that these are seasonal rather
than year-round operations. As mentioned previously, the
nature of the organic material in the wastewater will affect
the limiting organic loading. Wastewaters containing a
high percentage of sugars, for instance, can be applied at
a higher organic loading rate than wastewaters containing
mostly starchy or fibrous material [93] .
Ill
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Table 22. Organic and Hydraulic Loading Rates
of Selected Industrial Wastewater Land Application Sites
Site location
or reference
Seabrook,
Xcw Jersey
[<>1]
[122]
Bridgeton,
New Jersey
[08]
Suntcr,
South Carolina
L'Anse,
Michigan [93]
14]
Ac t on ,
Canada [91]
Firth, Idaho
Fremont ,
Michisan [3SJ
Fairmont,
Minnesota
l)/""-'re/day
Vegetable 16 -- 12
processing
Cannery -- -- ft . 4 -10
Corn -- -- 3.4 8 fa (I
process ing
Tomato J -- 2.5
processing
Kraft mill 1 1 ,000 1.8 -120
Poultry J.75 520 0.9 110
process ing
Board mill O.d 1,200 0.55 138
Citrus O.S2 '3,300''* 0.45 350
process in)*
Tannery 1.2S SOO 0.45 50 (600)11
Potato 0.63 1,200 0.3 78
processing
rood o.s i.oon 0.3 74
processing
Food 1.5 1.500 0.1 47
processing
a. Estimated from COD measurements.
b. Loading during spring.
Loading rates for nutrients or other chemical constituents
normally are not limiting factors for industrial waste-
waters suitable for land application. Exceptions to this
on an industrywide basis are wastewaters from the dairy and
meatpacking industries. Total nitrogen concentration due to
milk spillage has been reported as high as 300 mg/L [59].
Application of this concentration of nitrogen at normal hy-
draulic loading rates would far exceed the nutrient uptake
capacity of a cover crop and would undoubtedly result in
leaching of significant quantities of nitrates into the
groundwater. There will, of course, be individual pro-
cessing plants with high levels of nutrients or chemicals
112
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in their wastewater as a result of specialized processing
operations. In such cases, the possibility of loading
limitation because of these constituents must be considered.
In some cases, pulp and paper installations in particular,
nutrients may be deficient, and supplementary fertilizers
must be added with the wastewater to promote cover crop
growth and maintain biological activity in the soil. The
soil must be tested initially and routinely to determine
if sufficient nutrients are being supplied. Nutrient addi-
tion will be discussed further under "Operation and
Management."
Distribution and Collection System The major method of
application of industrial wastewater has been with
sprinklers. The ridge and furrow method has found limited
application and flood irrigation even less. Spraying has
become the predominant form of application for several
reasons. Most importantly, sprinklers distribute the or-
ganic and solids load of the wastewater more uniformly over
the site. This is important with relatively high strength
wastewaters because it prevents portions of the site from
becoming overloaded. Sprinkler systems .are more readily
adaptable to the widely varying wastewater flows \vhich
often occur in industrial processing. Additionally, there
is less land preparation required with sprinkler
application. The design of sprinkler systems has been dis-
cussed in detail in Section IV. It should be mentioned
here, however, that the selection of the type of sprinkler
system, permanent versus portable, etc., is a matter of
economics and will depend on the operating season of the
processing plant.
The ridge and furrow distribution method is best suited to
smaller systems where close control of large volumes of
wastewater is not required [84]. This method has also
been applied to several systems where the wastewater is
apparently toxic to vegetation [105, 91]. Level or very
gently sloping land is required for ridge and furrow dis-
tribution to be effective. Additionally, the system should
have relatively permeable soil to reduce the amount of sur-
face clogging that may occur because of the deposition of
solids.
The use of border strip irrigation with industrial waste-
waters has limited applicability when a cover crop is used.
Suspended solids contained in most industrial wastewaters
are deposited at the head end of the strip or basin, over-
loading that area and choking out the vegetation. The
method has been applied with limited success at a potato
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processing plant in Lewisville, Idaho, and at a tomato can-
nery in Thornton, California. It is better suited to sys-
tems which are operated as infiltration basins without
vegetated surfaces. This system has been used effectively
in the wine industry for disposal of stillage wastewaters
[22].
The use of large seepage or percolation ponds, such as
those used for groundwater recharge with municipal waste -
waters, has not been feasible with industrial wastewaters.
The relatively high BOD and suspended solids concentrations
make aerobic conditions difficult to maintain in the upper
soil layers. A method combining the principles of the
ridge and furrow method and spread basins has been used to
infiltrate citrus wastewaters. The method, referred to as
back-furrowing, uses a system of interconnected furrows to
spread the wastewater evenly over an area. The ridges be-
tween the furrows allow air to enter the soil and maintain
aerobic conditions during spreading. Odors were thus elimi
nated, and infiltration rates were maintained at a much
higher level than with seepage basins [4, 62].
If underdrain piping is employed, then effluent collection
and discharge facilities must be included in the design.
These items are covered under the discussion on the over-
land flow method .
Surface Vegetation Systems5 that use sprinklers for waste-
water application require some type of vegetative ground
cover to prevent soil erosion and sealing of the infiltra-
tive surface due to the action of water droplets [61].
There is one system reported that sprays very high strength
sulfite liquor wastewaters onto nonvegetated fields, but
not on a continuous basis. Between applications, the
fields are rejuvenated by treating with gypsum and growing
a cover crop.
The objective of most industrial wastewater land applica-
tion systems is to maximize hydraulic loadings, thereby
minimizing land area requirements. Experience at most in-
dustrial installations indicates that a cover crop is bene-
ficial in helping to increase and maintain infiltration
rates. The root structure tends to expand the soil and
promote dispersion of clogging material [65]. Vegetation
also increases the hydraulic capacity of the system through
removal of soil water by evapotranspiration. This water
consumption can be.a significant portion of the applied
wastewater for systems with low permeability soils. An ex-
cellent example of this is the food processing facility at
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Fairmont, Minnesota, where essentially all of the waste-
water applied is lost to the atmosphere by evapotranspira-
tion and any runoff is collected and resprayed. Only for
very permeable soil conditions is a cover crop not of sig-
nificant benefit [105]. At some installations the indus-
trial wastewater has proven toxic to vegetation. As
mentioned previously, the ridge and furrow method of appli-
cation has often been employed in such cases.
When maximum hydraulic loading is the objective of the sys-
tem, the cover crop should be selected with this in mind.
As mentioned under "Treatment by Overland Flow," hydro -
phytic, perennial grasses are the most suitable crop.
These grasses have also proven to be more tolerant to the
high organic loadings often used in industrial systems.
Reed canary grass is the species that has been applied with
widest success, although it normally requires considerable
time to become completely established.
Some systems have applied wastewater to naturally vegetated
areas and have relied on natural ecological succession to
establish a suitable vegetative cover. 'The most notable
examples of this approach are the food processing installa-
tions at Seabrook Farms, New Jersey, and Bridgeton, New
Jersey, where wastewaters are loaded at very high rates on
naturally wooded areas. However, for most systems, espe-
cially those with low or moderately permeable soils, it
would be preferable to hasten the maturing of a system by
the purposeful establishment of a hydrophytic species.
Cash crops, such as alfalfa, corn, and peanuts, have been
successfully used as cover vegetation, but in many cases,
attempts to maximize hydraulic loading at the site has re-
sulted in overwatering and killing of the crop [32] . When
such crops are grown, standard practices of irrigation must
be used. Consultation with local farm advisers or agricul-
tural extension service representatives on the subject of
crop selection and suitable irrigation practice can be
helpful.
Other Considerations The design of a system must consider
the climatic effects, such as rainfall and temperature
variation, on the system. Designing for seasonal changes
has been discussed at length in previous sections on munic-
ipal wastewaters. It is interesting to note here, however,
the apparent disagreement in the literature on the feasi-
bility of winter operation of industrial land application
systems. Some systems, notably the Seabrook Farms and the
Fremont, Michigan, facilities [35], provide continuous
spraying of wastewater through the winter without adverse
effects on the vegetative cover. At other systems, such as
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the tannery wastewater facility in Acton, Canada [91], it
has been -demonstrated that the buildup of ice on the soil
is injurious to the vegetation. On the basis of this con-
flicting experience, it appears that the feasibility of
cold weather application of industrial waste must be deter-
mined for each individual case.
Operation and Management
The operation and management of irrigation and infiltration-
percolation systems has been discussed under the respective
sections for municipal wastewaters. The reader is referred
to those sections for a more detailed discussion on the
subject. Specific considerations for industrial wastewater
systems will be discussed here.
Loading Cycles The cycling of wastewater application must
be adjusted to avoid ponding of the wastewater on the field
which results in prolonged anaerobic conditions in the soil
mantle. The optimum loading cycle must be determined
through experience for each individual system. Operating
schedules reported in the literature commonly call for one
day of application followed by several days of drying. An
extreme case occurs for a system in Terre Haute, Indiana,
which handles very high sodium pulping liquors. The system
is operated until ponding begins to occur; then it is
rested for several years [43].
Adjustment of the loading cycle will be required to compen-
sate for changing weather conditions. The winter operation
at the Fremont, Michigan, and the Seabrook, New Jersey,
facilities entails continuous spraying from a few sprink-
lers to prevent freezing [35]. Odor problems have arisen
at the Beardmore site in Canada as a result of the spraying
of anaerobic wastewater which had been stored during the
winter. The problem was minimized by loading the stored
waste onto the land at a rate several times the normal oper-
ating rate [91].
As mentioned previously, growing of cash crops requires that
normal irrigation practice be followed. In this regard it
is often helpful to have experienced farm personnel operate
the system.
Field Management Field management activities include:
(1) maintaining the infiltrative capacity of the soil sur-
face; (2) harvesting of cover crops or otherwise controlling
the vegetative cover if used; and (3) supplementing the soil
with fertilizers or soil amendments as necessary.
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Properly loaded systems with vegetative cover do not nor-
mally require mechanical assistance in maintaining infil-
tration rates. Systems without ground cover, however, do
require disking or other tilling normally after each
application to reopen soil pores and restore the infiltra-
tive capacity of the system. The frequency of such opera-
tion must be determined individually for the system in
question.
Harvesting of a cover crop is definitely required if nutri-
ent removal is an objective of the system, and is obviously
necessary if a cash benefit is to be realized. Scheduling
the harvest for maximum crop value should be considered, as
discussed under overland flow treatment.
Many systems report cutting but not harvesting of the vege-
tative cover. This procedure may be of benefit for systems
that handle nutrient deficient wastewaters, as often found
in the pulp and paper industry. The decay of cut vegeta-
tion will provide a recycle of plant nutrients, thus mini-
mizing the need for supplemental fertilizers. Vegetative
litter may also prove beneficial by providing additional
media for microorganisms. A good example,, of this situation
has occurred at the system in L'Anse, Michigan, which
handles hardboard mill wastewater. There is a danger in
generating too much vegetative litter, which can exert a
substantial BOD loading of its own on the system and thus
limit its renovative capacity. Matting of tall cut grass
on the soil surface can hinder drying of the soil surface
and thus promote anaerobic conditions. This situation was
encountered at the tannery wastewater facility in Acton,
Canada, and was remedied by cutting the grass at frequent
intervals [91]. It is generally recommended that the
ground cover not be allowed to grow too tall even if it is
to be harvested. Tall vegetation can interfere with the
operation of the distribution system, hinder soil drying,
and promote the propagation of insects if ponding does
occur.
The use of irrigated fields for cattle grazing has been
attempted; however, it was found to require excessive land
areas in order to prevent severe soil compaction as a re-
sult of cattle traffic [84]. Cattle also tend to brush
and rub against the risers which results in breakage [44].
It is concluded that grazing is generally not compatible
with most industrial wastewater land application systems.
Supplemental fertilizers may be required for systems
handling nutrient deficient wastewaters. The frequency of
fertilizer application should be determined through moni-
toring for soil nutrients. Lime or gypsum may be required
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for soils receiving high sodium waters, or waters with very
high or very low pH values.
Monitoring Monitoring of applied wastewater flow rates
and quality, even if not specifically required by regula-
tory agencies, is good operating practice. Monitoring
results provide a basis for process control and any future
design. Monitoring is especially important if there is a
potential for groundwater contamination as a result of
applying specific pollutants to the land. In addition, the
results gathered from monitoring programs provide the basis
on which decisions regarding changes in loading rates or
operational practices can be made.
Treatment Efficiency It has been reported that the
soil mantle is capable of removing essentially all degrad-
able organic matter and most of the suspended solids from
wastewaters even when loaded at rates up to 200 Ib BOD/
acre/day [12] . Successful operation has been reported for
substantially higher loading rates when applied on a sea-
sonal basis [4] . This excellent removal efficiency has
been found to be independent of the soil type [12] . In an
effort to maximize loadings, however, several cases of
groundwater pollution have resulted, as discussed under
"Environmental Effects."
An example of the organic and solids removal efficiencies
for underdrained irrigation is shown on Table 23. The
wastewater is from a poultry processing plant in Sumter,
South Carolina. The hydraulic and organic loading rates,
shown in Table 22 for this system, are moderate and typical
of many installations. The effluent quality was determined
after the wastewater had passed through 5 feet of sandy
soil and was collected by the underdrains.
The removal efficiency of land systems with regard to re-
fractory organics, such as lignins and pesticides, and
inorganic chemicals, such as heavy metals and nutrients,
is dependent on the soil structure. Generally, the higher
the clay and organic content of a soil, the higher the re-
moval capacity. Although the theory of the removal mecha-
nisms is known, the practical application of the theory to
actual installations has generally been lacking. There is
a paucity of quantitative information in the literature on
the removal efficiencies of soil systems with regard to the
above constituents. This is an area requiring further
study.
For systems using cover vegetation and moderate hydraulic
loadings, nutrient removal is primarily a function of plant
uptake. Clay soils will retain nutrients in the root zone
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Table 23. Characteristics
of Sumter Plant Wastewater
Characteristic
Raw
wastewater
Treated .
effluent'
BOD, mg/L
Suspended solids, mg/L
Total solids, mg/L
COD, mg/L
pH
518
233
475
708
6.6
4
74
224
36
6.8
a. After passage through 5 feet of sandy soil.
longer than sandy soils, thereby providing a greater oppor-
tunity for removal. Aside from the extensive studies per-
formed at Paris, Texas, for the overland flow system, very
little has been reported in the literature on the nutrient
removal efficiency of in situ cover vegetation.
Operating Problems Operating problems can be placed in
three general categories: (1) those related to system
mechanical design and equipment failures; (2) those related
to system loading and management; and (3) those related to
natural phenomena. Problems encountered in the first cate-
gory related to design are discussed under the overland
flow method. A common problem reported in the literature
for industrial installations is clogging of sprinkler
nozzles that is due to failure in the pretreatment screen-
ing operations. Careful inspection and maintenance proce-
dures are necessary to minimize this type of problem. Using
too small a nozzle size has resulted in frequent nozzle
clogging at some installations [44].
Under the second category, the most common problem encoun-
tered is odor production from storage or settling ponds.
This problem and its remedies are discussed under the
section on pretreatment. Damage to cover vegetation caused
by hydraulic and organic overloads has also been a common
occurrence. Avoiding this problem is a matter of knowing
the capacity of the system and operating within that
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capacity. Haphazard operating procedures are an invitation
to problems.
Problems in the third category include primarily those re-
sulting from the weather, although vandalism should also be
mentioned. Rainfall can disrupt harvesting operations and
unusually intense rainfall can overload and damage the
system. An adequate safety factor must be used in the sys-
tem to deal with such design occurrences. There are, of
course, problems associated with operation during freezing
weather. The major ones include pipe freezing, vegetation
damage caused by ice buildup, and loss of treatment
efficiency. Operating procedures to mitigate such problems
have been discussed previously.
ENVIRONMENTAL EFFECTS
The effects of land application of wastewater on the soil
ecosystem have been identified in previous sections and are
discussed to some extent under pretreatment requirements in
this section. The discussion here will be limited to im-
portant environmental effects particular to industrial
wastewater land application systems.
Organic Overloading
Organic overloading can have a marked effect on the soil
vegetation and groundwater. Laboratory studies conducted
on pulp and paper wastewaters indicated that when the or-
ganic capacity of the system is exceeded, vegetation is
damaged or killed completely, anaerobic conditions develop
which lead to severe clogging of the soil, and undegraded
organic matter is leached through the soil and can enter
the groundwater [12] . These effects were confirmed in the
field at an experimental system in L'Anse, Michigan [107].
The system was loaded at a rate of 2,000 Ib BOD/acre/day.
The vegetation was quickly killed, and the soil permeability
was reduced substantially.
Sodium Effects on Soil
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 recover. Sodium effects on
overland flow systems are less critical because the infil-
tration rates of the soils are already quite low.
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IDS Effects
The effects of dissolved salts on the vegetation and ground
water is of primary concern to industries which produce
high TDS wastewaters. A good example of the situation that
can develop is the tannery system at Acton, Canada. The
wastewater there has a salt concentration reaching
3,000 mg/L. Leaching of this salt through the soil has
substantially raised the salt concentration of the ground-
water in the area. Although concentrations have not
reached U.S. Public Health limits, complaints by local
residents are threatening the existence of the plant [91].
Effect of Mosquito Propagation
At several California installations the major adverse en-
vironmental effect has been the propagation of mosquitoes
due to hydraulic overloading of the spray fields. At
Hunt-Wesson, Davis, California, the problem was antici-
pated, and mosquito fish or gambusia were planted in the
runoff collection sump. For spray irrigation, ample drying
must be scheduled in the operation to prevent massive mos-
quito propagation.
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SECTION VII
CLIMATIC CONSTRAINTS ON LAND APPLICATION
Climatic constraints on land application and the effects of
systems on the climate have been discussed individually in
Sections IV, V, and VI for irrigation, infiltration-
percolation, and overland flow. The intent of this section
is to present a comprehensive discussion of (1) climatic
classifications within the United States as they affect
land application systems, and (2) local climatic effects
from operation of large land application systems.
CLIMATIC CLASSIFICATION FOR LAND APPLICATION SYSTEMS
Climates can be studied, analyzed, and finally classified
in many different ways depending on the purposes for which
the classification is to be used. A climatic classification
for agricultural purposes is quite different from one for
human comfort, or for water resources. Thus, any considera-
tion of the climatic constraints to land application tech-
niques leading to a division of the climates of conterminous
United States into large and fairly homogeneous regions,
on the basis of their influence on the type of operation
of land application systems, may result in a classification
entirely unlike those achieved for other purposes.
Before one can begin to discuss the geographic variations
in land application techniques imposed by climate, it is
first necessary to understand how climate may influence the
operation of a land application facility and what climatic
factors can be considered truly "active" in terms of con-
trolling the success or failure of a treatment system. It
is clear that important climatic factors must involve ele-
ments of heat and moisture. In irrigation and overland
flow systems, the vegetation cover is certainly a major
contributor to the success of the systems. Vegetation re-
quires moisture and both the rate of growth of vegetation
and of decomposition of many solids in the effluent are
regulated in large part by the energy available. Thus,
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climatic factors, such as "effective precipitation" (that
part of the precipitation which enters the soil and is
useful for plant growth and development) and net radiation
(the balance between the incoming and outgoing radiation,
or the usable energy at the earth's surface), are much
more important and deterministic than are the standard
degrees of temperature or inches of precipitation.
Thornthwaite [127], Thornthwaite and Mather [128], and
Mather and Yoshioka [75] have all identified the active
factors of climate for vegetation growth and development
as potential and actual evapotranspiration, the moisture
index (made up of indices of humidity and aridity) thermal
efficiency, and precipitation effectiveness. These some-
what complex sounding terms and indices all involve ways
of expressing the influence of the energy and moisture
factors in climate on the growth and well-being of vegeta-
tion or on the progress of biologic activity.
Energy Constraints
The major climatic constraint to the operation of a land
treatment facility clearly involves the energy necessary
for plant growth and the continuation of biologic
decomposition. Energy receipts are directly related to
latitude since the sun ultimately is the source of the
energy received by the earth's surface. In winter, both
daylength and the sun's angle decrease northward. Less
intensity of energy is received for a shorter period of
time so total receipts of energy decrease rapidly northward;
the intensity of cold conditions increases markedly. In
summer, daylength increases to the north while the angle
of the sun's rays still decreases northward. The oppor-
tunity to receive energy for a longer period of time some-
what balances the decreasing intensity of radiation as
one goes northward so that total receipts of energy are
much less variable latitudinally in summer than in winter.
This seasonal difference in energy receipts is reflected
in latitudinal differences in air temperatures. July
temperatures at Des Moines, Iowa, average 77.4 deg F
while temperatures average 81.1 deg F in the same month in
New Orleans, less than a 4 deg F difference. In January,
the average Des Moines temperature is 22.6 deg F while at
New Orleans it is 54.1 deg F, a difference of over 51 deg F.
Thus, clearly, in defining climatic constraints to land ap-
plication, one would expect a strong latitudinal variation
because of the significantly different energy receipts
especially in the winter season of the year, or because of
the strong dependence of annual temperature range (differ-
ence between highest and lowest temperatures for the year)
on latitude.
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Moisture Constraints
Moisture constraints to efficient operation of land applica-
tion systems also exist. Here, the problem is twofold.
First, climates differ appreciably across the United States
in both total annual amount of precipitation and in seasonal
distribution. In general, in eastern and central United
States, precipitation is fairly well distributed throughout
the year although it decreases in total amount to the north
because of the general decrease in air temperature. Cold
air holds less moisture at saturation than warm air. A
similar degree of cooling of saturated cold and warm air
will release more moisture from the warm air than from the
cold air. Total precipitation amounts decrease westward
across eastern and central United States because of in-
creasing distance from one major source of moisture, the
Gulf of Mexico. North Dakota has the lowest total precipi-
tation of any state east of the Rocky Mountains.
In the western United States, there are areas like the
deserts and steppes of the Great Basin area or the south-
western states with little or no precipitation at any
time of the year, while the more coastal areas of California
experience marked seasonal patterns in rainfall. In the
so-called Mediterranean climates of California, there
is a clearly defined winter wet season and a summer dry
season. Thus, the climates of California are quite distinct
from those of Arizona and New Mexico, and both of these
are quite different from the fairly well distributed patterns
of precipitation found throughout most of eastern and
central United States. While other patterns of precipitation
exist in the United States, these three major subtypes,
on the basis of total amount and seasonal distribution,
appear to be most influential in terms of land application
operations.
The second moisture problem relates to the intensity of
storm precipitation. If the month's rainfall is well
spaced through the month, a larger proportion of the pre-
cipitation will be able to infiltrate and to be lost from
the upper soil layers by evapotranspiration and deep
percolation. There should be little effect on the land
application system. If, however, the month's precipitation
comes as a result of one or two intense storms, all of the
water will not infiltrate, there will be runoff, ponding in
low areas, erosion, and the opportunity for effluent in the
land application area to be washed into the surface water-
courses and out of the treatment area without adequate
decomposition. Greater care has to be taken in areas of
possibly intense precipitation to prevent surface runoff
124
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from developing. While all areas of conterminous United
States can experience intense short-period storm rainfall,
it is clear that lower latitude areas where intense thunder-
shower activity, hurricanes, and squalls are most frequent,
are the areas of prime concern in this regard.
Heat and Moisture Effects
Heat and moisture factors influence the operation of a land
application system in several important ways. First, in
all such systems, there is the need to have the land area
adequately covered by vegetation not only to prevent erosion
but also to serve as the habitat for the microorganisms
that ultimately break down and digest any solids removed
from the effluent. For vegetation development, energy com-
bined with adequate amounts of moisture are prerequisites.
Most places in conterminous United States have sufficient
energy for the development of a good ground cover of vegeta-
tion (although the composition of this cover may change
from one region to another). Adequate amounts of moisture
during the growing season are not found in all areas and
so in some areas (or in nearly all areas at some time) fresh
water supplies for irrigation purposes may be necessary dur-
ing the period of development of the vegetation cover or to
keep vegetation healthy during periods when use of the sys-
tem is not contemplated.
Second, energy is required in the process of breakdown of
the organic material removed from the effluent. The rate
of microbial activity is directly related to the available
energy as expressed by the temperature. It has been ob-
served that bacterial reaction rates double with every 18
deg F rise in temperature until some limiting temperature
is reached [80] . According to the temperature range in
which they function best, bacteria may be classified as psy-
chrophic (54 to 64 deg F), mesophilic (72 to 104 deg F) , cr
thermophilic (131 to 149 deg F) [80] . Most soil tempera-
tures are suitable for the development of mesophilic bac-
teria which can survive at temperatures up to 113 deg F.
At temperatures above this maximum, the rate of oxidation
of solids again slows. Since in a land application system
adequate moisture should always be present to maintain
evaporative cooling of the surface layers, this maximum tem-
perature is seldom reached.
Third, energy receipts are directly related to
evapotranspiration. While most land application systems
are not primarily designed to dispose of all effluent by
evapotranspiration, such a water loss must certainly be con-
sidered in any overall water balance of the treatment area.
125
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During periods of high temperatures (> 75 deg F mean daily
temperatures) more than 0.2 in./day of evapotranspiration
can occur. This is equivalent to over 27,000 gal. of water
loss per acre every 5 days. In periods without rain,
this appreciable loss from the system results in less water
infiltrating or running off over the surface. Annual values
of evapotranspiration from an always moist surface vary
from over 40 inches across Florida, southern Alabama,
Mississippi, Louisiana, Texas, and the lower-lying areas of
southern California and Arizona to less than 25 inches
through New England, New York, Michigan, Wisconsin,
Minnesota, the Dakotas, and most of the Rocky Mountain
states. Since summer temperatures are not that different,
as has been noted, it is the total length of the period of
evapotranspiration that results in these significant differ-
ences from south to north across the country.
Fourth, the length of the below freezing winter period is
quite important in the selection of the land application
system. Land application is possible at low temperatures
as long as the effluent does not freeze in the distribution
laterals or in the spraying equipment. However, little
purification occurs at temperatures near or below freezing
and the effluent may freeze into big mounds of ice around
the places where it is being applied to the land, possibly
harming the vegetation. Most systems must be designed to
store effluent or to utilize other means of treatment
during such low temperature periods. A nationwide mapping
of soil temperatures as related to ambient air temperatures
would be helpful in planning land application facilities.
Fifth, as has been mentioned previously, adequate moisture
is necessary not only for the development of the vegetation
cover but also for the survival and well-being of the micro-
organisms that serve to break down the solids removed from
the effluent. This is usually not a problem in a land
application system since adequate effluent is usually avail-
able to prevent undue drying of the surface soil layers.
Sixth, the type of system employed must consider not only
the daily anticipated loading of effluent but also any
possible overloads resulting from heavy rainstorms. While
the additional rainwater will dilute the effluent already
applied to the land, this is. of little value if that efflu-
ent is already very heavily loaded with solids and with a
high BOD. Possibly more critical are the effects of the
additional rain from long duration, low intensity storms.
These storms provide little dilution and yet greatly affect
the moisture balance. Some leeway must be incorporated
into the design of land application systems in anticipation
126
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of both intense short period rainfall occurrences and long
duration, low intensity rainfall.
CLIMATIC ZONES FOR LAND APPLICATION
On the basis of the foregoing plimatic analysis, it is
possible to subdivide conterminous United States into a
relatively small number of zones or areas in which climatic
conditions pose quite similar constraints to the operation
of land application systems. Of course, microclimatic dif-
ferences or local soil, vegetation, or slope conditions
within these broad areas might outweigh the general cli-
matic considerations in the selection of the type of system.
Still, within the large areas depicted, the major climatic
factors of energy and moisture are similar enough to sug-
gest similar methods of land application although local
considerations must be carefully analyzed before any final
decision is achieved.
In preparing a map (Figure 10) showing five general climatic
zones in conterminous United States for land application
purposes, the user and his understanding of climate has been
kept carefully in mind. Thus, the map is not intended for
the climatologist but rather for the engineer, the state or
local official, or others who are concerned with land appli-
cation but who do not have a great deal of knowledge about
climate and its variation from place to place. The first
effort has been to use state borders to outline the climatic
zones if at all possible. Climates do not, of course,
change abruptly at state boundaries but since such bounda-
ries are simple to utilize for descriptive or regulatory
purposes, their use was dictated here.
The map has two major features. First, there is a general
east-west zonation, east of the Rocky Mountain area which
represents the general decrease in temperature as one goes
northward across the United States. Second, there is also
some slight north-south zonation, especially across the
western United States, representing the general change in
precipitation amounts and seasonal distribution found in
this area. Average monthly temperature and precipitation
values for representative stations in each of the five cli-
matic zones are listed in Table 24.
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. This area has essentially no rainfall in
the summer months and a precipitation maximum in winter.
Average annual precipitation is about 15 to 25 inches con-
fined generally to the 6 months from November to April;
127
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I .
00
CLIMATIC ZONES
MEDITERRANEAN CLIMATE -
DRY SUMMER - MILD, WET WINTER
ARID CLIMATE - HOT, DRY
HUMID SUBTROPICAL - MILO WINTER
(WASHINGTON, OREGON AREA MILO
HUMID CONTINENTAL
HUMID CONTINENTAL
SHORT WINTER
HOT. WET SUMMER
MOIST SUMMER)
HOT SUMMER
LONG WINTER. WARM SUMMER
FIGURE 10
GENERALIZED CLIMATIC ZONES FOR LAND APPLICATION
-------
Table 24. Average Monthly Temperature and Precipitation
Values at Representative Stations in Each
of the Five Climatic Zones
ts»
VO
Zone
A
A
B
«
C
C
C
1)
0
u
i:
£
Location
Sacramento, Calif.
lot Angeles, Calif.
Midland, Tex.
Phoenix, Ariz.
Macon, Ga.
Little Rock, Ark.
Portland, Ore.
Columbus, Ohio
Omaha, Neb.
Spokane, Wash.
Albany, N. Y.
Huron, S. 0.
Th
I>b
T
P
T
P
T
P
T
P
T
l>
T
P
T
P
T
P
T
P
T
P
T
P
Jan
46.2
3.19
5S.8
3.07
44.1
0.79
SO. 7
0.75
49.3
3.39
40.6
i /4
38.5
S.3S
31.6
2.91
22.3
0.83
2S.3
2.44
25.7
2. 52
12.6
0.47
Fe1>
SO. 2
2.99
57.0
3. 35
48.4
0.59
54.5
0.87
51.1
4.25
44.4
4.33
42.1
4.21
32,7
2.20
26.4
O.D4
30.0
1.85
26.8
2.24
16,5
0.59
Mar
54.3
2.36
59.4
2.24
55.2
0.35
60.4
0.67
56.8
4.92
51.8
4.80
46.0
3.82
40.5
2.87
36.9
1.46
38.1
1.50
35. 8
2.87
28.8
1.10
Apr
59.9
1.42
61.9
1.18
64.9
0.83
68.7
0.31
65.7
3.74
62.4
.4.92
51.8
2.09
52.0
3.35
51.6
2. 56
47.3
0.91
48.4
2.91
45.0
1.85
May
66.0
0.59
64.8
0.16
73.4
2.09
77.0
0.12
73.9
3.31
70.5
5.28
57.4
2.01
63.1
3.46
63.0
3.46
55.8
1.22
59.9
3.62
57.6
2.36
June
72. S
0.12
68.0
0.08
81.1
1.61
85.6
0.08
80.8
3.35
79.0
3.62
62. -1
1.6S
72.7
3.78
73.0
4.53
61.3
1.50
69.1
3.74
67.6
3. IS
July
7.7 . 4
Trace
73.0
Trace
.82.9
1.89
91.2
0.79
81.9
5.63
81.9
3.3S
67.3
0.39
76.5
X3.66
78.4
3.39
69.4
0.39
73.9
4.29
75.0
1.81
Aug
76.1
0.04
73.0
0.04
82.2
1.50
89.1
1 .10
81.3
4.17
81.3
2.83
66.6
0.67
74.8
2.80
76.3
3.98
67.5
0.39
71.8
3.31
72.9
2,09
Sept
73.6
0.20
72.0
0.24
7S.4
1.77
84.4
0. 75
76.5
2.76
74.3
3.23
62.2
1.61
67.8
2.32
66.9
2.64
59.9
0.75
63.7
4.02
61.9
1.54
Oct
64.9
0.79
67.5
0.39
65.8
1.65
72.1
0.47
66.2
2.01
63.1
2.87
54.1
3.62
56.5
1.89
55.8
1.73
48.6
1.57
53.1
2.83
48.7
1,14
Nov
54, J
1.46
62.8
1.06
52.5
0.47
59.2
0.47
55. 4
2.44
49.5
4.13
45.1
S.31
43.3
2.24
38.8
1 .26
35.2
2.24
41.7
2.91
31.3
0.67
Dec
47.5
3.23
58.3
2.87
45.9
0.67
52.5
0.87
48.9
4.06
41,9
4.09
41.4
6.38
33.4
2.24
28.2
0.79
29,7
2.44
29.5
2.72
18.9
0.55
Annual
61.9
16.30
64.4
14.69
64.2
14.25
70. S
7.20
65,7
44.09
61.7
48.66
S2.9
37.17
S3. 8
33.74
SI. 4
27.56
47.3
17.20
49.8
37.95
44.8
17.32
a. Temperature, dcg F.
b. Precipitation, in.
-------
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 sea-
sons for some plant growth. Storage of effluent due to
freezing will not be necessary but may be desirable because
winter crop needs will usually be lower than those in
summer. Data for Sacramento and Los Angeles in Table 24
are typical of conditions in Zone A.
Zone B covers the area of Nevada, Utah, Arizona, and New
Mexico, as well as the eastern portion of California and
the western portion of Oklahoma and Texas. This zone rep-
resents the very hot arid climates of conterminous United
States. They experience large receipts of energy in most
seasons of the year. Winter storage of effluent should not
be a concern although there are cases, such as at Portales,
New Mexico, where winter storage is used. There may also be
problems of salt in the soil if groundwater or brackish
water is used in irrigation or constitutes a significant
portion of the effluent. Clearly these climatic conditions
do not describe the mountainous areas where, because of
elevation and orographic effects, temperatures are consid-
erably cooler and precipitation more adequate. Thus care
must be exercised in designing land application systems in
Zone B because of great local variations in climatic
conditions. However, the general climate of the region can
be fairly well represented by conditions at Phoenix,
Arizona, and Midland, Texas.
Zone C covers primarily the states identified as the Mid-
and Deep South. This means all states south of and in-
cluding Oklahoma, Arkansas, Tennessee, Virginia, Maryland,
and Delaware, except for the panhandle areas of Oklahoma
and Maryland. In addition, the western portions of
Washington and Oregon are included in this zone. This is
classified as a generally humid subtropical type of climate
with precipitation fairly well distributed through the year
(with the possible exception of western Oklahoma and Texas) ,
and with hot, muggy summers and fairly mild winters. In
general, precipitation varies from 40 to 60 inches during
the year, and temperature ranges from the low 40s in winter
to the low 80s in summer. These ranges do not hold for the
Washington-Oregon area which experiences mild winters as
well as mild summers. This latter area is included within
Zone C because it has sufficient moisture from precipita-
tion through the year (the Washington-Oregon area will have
low precipitation in mid-summer for about 2 months) for
the growth of vegetation and the temperatures are mild
enough to eliminate any real danger from winter freezing.
Twelve-month operation of a land application system is pos-
sible in most areas of Zone C as it is in Zones A and B.
130
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Little Rock, Arkansas, Macon, Georgia, and Portland, Oregon,
provide typical climatic data for Zone C stations.
Zone D covers eastern Oregon and Washington as well as the
central tier of states running in a band eastward from
Colorado through Missouri and Illinois to Pennsylvania and
New Jersey and into southern New England, including
Massachusetts and southern New York. The climate can be
described as humid continental, having moderately cold win-
ters (temperatures in the 20s and low 30s) , hot summers
(temperatures in the mid-70s), and precipitation well dis-
tributed through the year. The precipitation is entirely
adequate in the eastern portion but it is on the low side
in the western portion (Colorado, Nebraska, Kansas, as well
as Washington and Oregon). In general, there is sufficient
moisture to start vegetation on a land application area or
to keep it thriving if the system is unused for a while but
small amounts of irrigation might be needed in the western
portion. Winter temperatures are cold enough that storage
of effluent for a month or two might be necessary. Data
from Omaha, Nebraska, Columbus, Ohio, and Spokane,
Washington, represent climatic conditions existing in
Zone D.
Zone E covers the northernmost tier of states from Idaho
eastward across the Dakotas to Iowa, Wisconsin, Michigan,
and northern New England. These might also be called humid
continental climates but with very cold winters. Precipi-
tation occurs in all months of the year and averages 20 to
40 inches per year. Summer energy receipts are also suffi-
cient for the development of a good vegetation cover.
Winter operations are quite limited because the bitterly
cold \\rinter temperatures, with ice and snow, require the
storage of effluent for anywhere from 2 to 6 months. The
cold period is fairly continuous so that essentially no
periods exist during the winter months in which irrigation
is possible. Data from Huron, South Dakota, and Albany,
New York, might well represent conditions in this area.
The five broad zones illustrated in Figure 10 provide a
fairly simple and general classification of climates in
conterminous United States for the purposes of land appli-
cation operations. They should be considered only as
approximate, and climatic data from the immediate vicinity
of any proposed land application operation should be
studied in detail before any final decision concerning type
of system is made.
131
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LOCAL CLIMATIC EFFECTS FROM OPERATION OF LAND APPLICATION
SYSTEMS
Any discussion of the influence that large land application
systems might have on local climates must clearly focus on
energy and moisture factors. While man's influence on his
environment already has been great, his influence on the
climate has so far been of rather local consequence. The
cities he builds, the swamps he drains, or the reservoirs
he creates have changed the factors of the heat and mois-
ture balance over rather limited areas. The reason for
this lies mainly in the relative magnitudes of heat and
moisture involved in man's activities as compared with
those already available in nature. For example, Huff and
his associates [46] calculated an evaporation rate of
29,400 gpm or 2.2 tons/second from cooling towers used with
a 2,200-megawatt nuclear power plant. At the same time
they showed that the water flux into a medium-sized thunder-
storm might be of the order of 8.3 tons/second, nearly 4
times the amount of water being evaporated in the cooling
towers. Computations on a large-sized cumulonimbus--a thun-
derstorm with hail--provided a value of 1,650 tons/second
of moisture flux through the base and into the cloud. These
values found in nature are some 75 times larger than those
produced by man through the operation of very large cooling
towers.
The same authors provided one further comparison by calcu-
lating the flux of atmospheric water vapor through a ver-
tical section of the atmosphere 1 kilometer high and 10
kilometers wide (about equal to 4 square miles) with air of
specific humidity of 10 grams/cubic meter and a wind veloc-
ity of 10 meters/second (23 mph) . The moisture conditions
specified are quite realistic, being equivalent to saturated
air at 57 deg F or air at 50 percent relative humidity at a
temperature of about 77 deg F. Using such figures, it can
be shown that some 1,100 tons/second of moisture would pass
through the vertical section or about 500 times the moisture
flux from the cooling towers. Such computations can be re-
peated many times; they continue to show that the quantities
of heat or moisture involved as a result of man's action are
usually quite insignificant when compared with the quanti-
ties of heat or moisture already present in the environment.
The operation of a large land application system for waste -
water can be considered to be similar to a large irrigated
tract or even to a large water body (reservoir or lake).
The extensive moist surface will modify atmospheric condi-
tions in several distinct ways. First, air over large
water bodies always experiences smaller diurnal and sea-
sonal changes in temperature than air over nonirrigated or
132
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drier surfaces. Water has a higher specific heat than soil
so that it will take a greater input of heat to cause a
water surface or moist soil to warm, say, 5 deg F than it
will a dry soil surface. With a greater heat capacity, the
moist surface will not cool as rapidly at night so that the
diurnal swings of temperature at the surface and in the air
above it will be less than over a dry surface. The same
argument applies to the annual ranges of temperature; the
effect of a large lake or moist tract is to reduce the sum-
mer peaks of temperature as well as to prevent the winter
extremes of cold temperature.
The second influence of large moist tracts or lakes would
be to increase the moisture content of the air over the
tract and downwind from the tract itself. Because of the
significant evaporation of moisture into any air mass
passing over the moist area, the air should be brought close
to saturation; atmospheric humidities downwind of the moist
tract should be appreciably higher than they are upwind from
the tract. To condense moisture out of air, it is necessary
to cool the air below its dew point temperature (the satu-
ration point). Thus, if air, after moving "off the moist
tract or lake moves upward over a rising land surface or is
cooled in contact with a snow surface, some condensation of
moisture may occur in terms of fog, clouds, or possibly
precipitation.
While the foregoing indicates the types of changes that
will occur as a result of the operation of a land applica-
tion system, the actual magnitudes of the changes that
result are still in question. Very few actual measurements
around such systems, under different climatic conditions,
exist. It is possible, of course, to obtain some informa-
tion by considering the types of changes that have occurred
around lakes and reservoirs or, in a few instances, around
large irrigation enterprises where observations have been
made. The following paragraphs describe a few results that
might serve to put the type of changes from a land applica-
tion system into proper perspective.
Effects on Climate Resulting From the Creation of Reservoirs
Rybinsk reservoir, located in northern Russia, somewhat
north and east of a line between Moscow and Leningrad,
covers about 4,570 square kilometers in area (about 1
million acres) . It is a fairly large but shallow body of
water in a humid continental climate (equivalent to Zone E
on the climatic map of conterminous United States). The
reservoir has been filled for more than 25 years so that it
has been possible to study conditions at many stations
133
-------
around the reservoir, both those influenced by the presence
of the reservoir as well as those far enough away to be un-
influenced by its presence.
Vendrov and Malik [132] , summarizing some of the results
achieved by others, indicate that the climatic change pro-
duced by the reservoir seems to be limited almost entirely
to the water area of the reservoir itself and to a narrow
shoreline zone several hundred yards wide. For example,
some investigators report diurnal temperature ranges just
0.6 mile inland from the reservoir shore were identical to
ranges found at much greater distances inland from the
reservoir. Other investigators have found this zone to be
slightly wider than 0.6 mile.
By comparing data at stations in existence before and after
filling of the reservoir, Vendrov and Malik conclude that
the change in local climate is actually noticeable in a
zone about 6 miles inland from the reservoir. In fact,
they established two zones of influence of the reservoir:
(1) a 6-mile wide zone of permanent active influence, and
(2) a zone running some 18 to 30 miles inland from the
shore in the downwind direction (and smaller distances in
other directions) in which episodes of influence are inter-
spersed with other periods of no influence. These authors
found that:
At the beginning of the warm season, the reser-
voir has a cooling influence, and in the second
half of the warm season a warming influence on
the surrounding region. Judging from the mean
daily temperatures, the cooling influence makes
way for a warming influence in the second or
third decade of July. The transformation of day
and night temperatures differs in character.
For the greater part of the warm season (in-
cluding August), the reservoir cools its sur-
roundings substantially in the day, and then
warms them very slightly in September and
October. Most of the warming effect of the res-
ervoir is at night '[132] .
The same authors find that the diurnal temmperature range
decreases within the entire zone of active influence, the
decrease being largest in summer and less significant in
autumn. More than 6 miles from the reservoir surface, some
change in diurnal temperature can be found in some years
(usually those with very warm summers) but not in others.
Along the southern border of the reservoir a decrease in
134
-------
maximum temperatures and an increase in minimum tempera-
tures can be found as far inland as 30 miles.
The effect of the reservoir on relative humidity
is limited to a relatively narrow belt up to 10
km [6 miles] wide. On the northern shore, the
width of the belt is apparently 5-6 km [3-4 miles]
and changes in relative humidity at points 10 km
inland can be traced only in the daytime in warm-
summer years [132] .
Vendrov and Malik list the following quantitative changes
within the zone of active influence of the reservoir. The
diurnal temperature range was decreased by as much as 2.9
deg C. The monthly maximum temperatures were reduced as
much as 3.5 deg C and the monthly minimum temperatures i^ere
raised as much as 4.6 deg C. Also, in the zone of influ-
ence the relative humidity increased as much as 18 percent
[132],
The results from the Rybinsk reservoir are similar to those
found elsewhere. For example, Borushko [13] indicated
that the 8-mile wide Tsimlyansk reservoir influenced air
temperature and relative humidity conditions over a 2- to
3-mile distance inland from the shore. Kolobov and
Vereshchagin [52] found that the width of the active in-
fluence zone was 4 to 6 miles around both the Kuybyshev and
the Volgograd reservoirs. Dubrovin [29] suggested the in-
fluence of the Kuybyshev reservoir on absolute humidity
extended 3 to 4 miles inland and this conclusion has been
substantiated by other investigators.
Effect of Large-Scale Irrigation on Climate
Sokolik [116] made a detailed study of the effect of an
irrigation enterprise in an arid region of Russia on the
heat regime of the surrounding area. Because of the rapid
evaporation of moisture into the air at the upwind edge,
there is a marked decrease in air temperature in the first
3,000 feet of movement across the irrigated tract. Further
movement across the irrigated tract results in only a small
further decrease in temperature. Moving out of the irri-
gated tract and over dry land again, the air very rapidly
increases in temperature due to turbulent mixing. Half of
the temperature drop is regained within the first 600 feet
of movement over the dry area while the remainder of the
temperature change is regained within another 3,000 feet;
some 3,600 feet inland from the downwind edge of the irri-
gated tract the temperature is the same as it was upwind of
the tract. The results, included schematically in
135
-------
Figure 11, emphasize the relatively small influence of an
irrigated tract on local climatic conditions.
Effect of Evaporation From Irrigation Sprats
Mather [74] investigated the evaporation of water being
sprayed from fixed overhead irrigation pipes and by large
rotating sprinklers. While the rate of evaporation is
about the same in both cases, the percentage of the applied
water that actually evaporated was considerably less in the
case of the rotating sprinklers since these sprinklers
applied a much greater volume of water per hour. The re-
sults of a few evaporation tests are summed in Table 25.
The figures show that as the distance downwind in the irri-
gated tract increases, the rate of evaporation into the air
becomes less. The greatest increase in the moisture con-
tent in the air occurs in the first few meters within the
irrigated area. Thereafter, the moisture increment becomes
smaller with increasing distance and will finally drop to
I ^> WIND MOVEMENT
3.000 FT
15.000 FT
600 FT
3 000 FT
FIGURE 11
TEMPERATURE CHANGE OVER AN IRRIGATED TRACT [116]
136
-------
Table 25. Dew-Point Temperature, Wind, Weather, and
Evaporation Observations in Fields Irrigated
by Overhead Irrigation Lines
Irrigation rate
Wind velocity
Sky
Crop
Dew-point
observed, deg C
7 metersc
3 meters
0.5 meters
Evaporation,
percent*1
Evaporation
increment,
percent6
a. Observation
b. Observation
Aug. 19, 1949
0.09 in./hr
6.5 mph
Scattered clouds
Broccoli
Downwind Downwind
Upwind 40 m 60 ra
17.0 17.0 16.8
17.5 18.0 18.1
17.8 18.7 18.5
28 21
3
Aug. 20, 1949 Aug. 27, 1949
0.09 in./hr 0.09 in./hr
4 mph 5 mph
Scattered clouds Clear
Broccoli Broccoli
Downwind Downwind Downwind Downwind
Upwind 40 m 80 m 120 m Upwind 45 m
10.1 10.6 10.5 10.3 23.0 23.0
10.4 10.6 10.7 10.8 23. J 23.6
11.3 12.0 11.9 11.9 23.5 24.0
14 7 4 17
00 9
Downwind
100 m
23.0
23.8
24.6
14
taken upwind outside irrigated area.
downwind. Distance downwind within irrigated area indicated in meters below.
c. Height of observation above ground.
d. Indicates evaporation as percentage of application from upwind to that observation point.
e. Indicates evaporation as percentage of application between indicated observation points within irrigated area.
-------
almost zero when the air nears saturation. The width of
this border area of rapid increase in moisture content of
the air depends on meteorological conditions as well as on
the amount of irrigation. Analysis of the figures in
Table 25 suggests that only in the first 40 meters within
the irrigated area is there much gain in moisture content
in the air. Clearly, less water is lost by evaporation in
an irrigation project if the size of the field irrigated is
made as large as possible.
Climatic Influences of Cooling Towers
To put the climatic effects of large land application sys-
tems into perspective, a comparison is drawn with large
cooling towers. Conditions around a cooling tower are not
entirely comparable to conditions around a land application
system since the tower releases vast amounts of heated air
along with the moisture evaporated. The land application
system will put moisture into the air but will not release
significant amounts of hot air to the atmosphere at the
same time. In the case of the cooling tower, the moisture
is inserted at essentially a point source while in the land
application site the source may be a square mile in extent.
These differences would suggest that conditions doivnwind
from the cooling towers should be changed to a greater, de-
gree than they would be downwind from a land application
system. Yet, investigators minimize the downwind effects
of cooling towers on atmospheric conditions. Thus, down-
wind effects of land application operations should also be
minimal.
Lacking quantitative information on the environmental in-
fluence of cooling towers, most researchers feel that some
changes in frequency or severity of fog, icing, clouds, pre-
cipitation, and possibly severe weather such as thunder-
storms may result. Increased frequency of fog and icing
conditions appear to be more likely to develop from the use
of short cooling towers while taller-type towers may result
in plumes that do not sink to the ground so that only
clouds develop. With the shorter (75- to 100-foot) towers,
McVehil [71] suggests that, at Zion, Illinois, on the
shores of Lake Michigan, there might be about 90 hours per
year of tower-produced fog at the highest frequency point
located 1.5 to 2.5 miles north of the towers as compared
with the present 160 to 260 hours per year of natural fog.
Maximum occurrence for tower-produced fog would be between
3 a.m. and 9 a.m. in the winter season. With winter tem-
peratures often below freezing, icing would be likely to
accompany the fog. Aynsley [7] indicates that humidity
increases can be found many miles downwind of cooling
towers.
138
-------
It must be pointed out that cooling towers should have
quite a different effect on the atmosphere than large land
application systems. While the volume of water evaporated
may be similar, the great amounts of heat available from
the towers, leading to possible cloud and thunderstorm
development, would not be present with land application
systems. Higher humidities certainly will occur downwind
of land application systems but since the moisture source
is much larger, the humidities will probably not be as high
and will exist over a wider but shallower band. Some icing
might accompany the operation of the system during below-
freezing conditions but since these conditions usually dic-
tate storage of effluent, the opportunities for icing
downwind of the system are greatly restricted. This is not
the case with cooling towers.
Precipitation Influences of Large Lake Areas
McDonald [64] has well illustrated the relatively negli-
gible effect of large water bodies on surrounding climates
by calculating the influence of "Lake Fallacy," an imaginary
lake 380 miles long and 50 miles wide stretching across the
southern border of Arizona. This lake would be slightly
larger than the combined areas of Lake Erie and Lake
Ontario. McDonald calculates that such a lake would be
necessary if one wished to augment the present July water
vapor flux into the state of Arizona of some 2 million
acre-feet per day by just 10 percent. He carefully points
out, however, that increasing the water vapor influx by 10
percent is no guarantee that precipitation will increase by
10 percent because the average residence time of water
vapor in the air is about 10 days. Using normal wind
speeds and trajectories, it is clear that most of the added
water vapor will be far from Arizona before it falls again
as precipitation. McDonald suggests that the only way to
create more local precipitation would be to pile up all the
dirt excavated in creating Lake Fallacy to form a 10,000-
foot mountain just downwind of the lake. Orographic cool-
ing of the air (whether augmented by additional moisture
evaporated from the lake or not) would then increase the
precipitation locally. As a final argument, McDonald points
to the very dry conditions existing around the Caspian Sea,
evaporating some 400 to 500 million acre-feet annually.
Only on the south where mountains squeeze moisture out of
the air is the precipitation appreciable. Around the rest
of the lake, arid and semiarid conditions point up the very
small influence that such a large wet surface has on local
atmospheric conditions.
139
-------
Conclusions
The climatic changes that accompany irrigation enterprises
are relatively local in magnitude. Air moving over an irri
gated tract will rapidly pick up moisture. 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 moistened area, turbulent mixing will
rapidly reduce the moisture content to its original low
value.
140
-------
SECTION VIII
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 waste-
water whenever possible.
IRRIGATION
The capital and operating costs for irrigation will be
evaluated in the following discussion. Also included is a
discussion of the economic benefits arising out of
irrigation.
Capital Costs
Capital costs for irrigation have been grouped into costs
for land, pretreatment, and for transmission and
distribution.
Land Costs for land can be a large part of the initial
capital cost. The flow and loading rate to be used will
determine the land requirements. The cost of land for 16
recently designed and completed systems in Michigan ranged
from $225 to $500 per acre [139]. The area required for
these systems varied from 38.5 to 400 acres.
A survey taken by the APWA of 69 municipal sites in the
United States showed that land costs ranged from $5 per acre
141
-------
in 1947 in Washington to $5,000 per acre in 1965 in
California. The median was about $500 per acre. In some
cases the land was already owned by the municipality, so
there was no charge for land made to the project. For the
six irrigation sites visited for this study, land costs
ranged from $100 per acre at Woodland, California, to
$800 per acre for the Idaho Supreme Company at Firth, Idaho.
One of the previous problems with purchasing land was that
there was no federal funding to help pay for it. Land
costs were not eligible for grants; consequently, the cost
had to be borne by a bond issue or similar funding. Under
the new federal law, land costs are eligible for grants if
the land is an integral part of the treatment system; if it
is not, they \^ill have to be paid for wholly by the oper-
ating municipality or industry. It may also be possible to
lease land as an alternative to outright purchase, or to
contract with local farmers or agricultural enterprises.
Pretreatment Pretreatment costs vary considerably with
the geographical area and the type of treatment. Smith
[114] investigated costs in June 1967 for conventional and
advanced treatment of wastewater. At that time, the
national average ENRCC (Engineering News-Record Construction
Cost) index was 675, and the STPCC (Sewage Treatment Plant
Construction Cost) index was 119.1 Because the STPCC index
better reflects the changing costs of treatment, it was
chosen to update Smith's costs to 1973 conditions. Pre-
treatment costs for a 1-mgd plant have been updated to an
STPCC index of 192.8 for January 1973 and are listed on
Table 26. Construction costs have been amortized over
25 years at 7 percent interest.
Capital costs for screening of industrial wastewater for
canneries are reported to be 0.14 to 0.29<£ per case of
product [61]. Vibrating 40-mesh screens, conveyors, and
hoppers in 1968 cost $19,000 per mgd for a 0.5-mgd instal-
lation, $12,300 per mgd for a 1-mgd installation, and
$8,700 per mgd for a 4-mgd installation [135]. For a
10-year life at 7 percent interest and 250 days of opera-
tion, this cost amounts to 0.7
-------
Table 26. Typical Costs of
Pretreatment for 1-mgd Plants [114]
January 1973 STPCC Index 192.8
Capital
cost ,
Type of
-------
Nesbitt and Allender [2, 87] reported amortized spray irri-
gation capital costs in 1967 dollars for a 1-mgd system
at 10^/1,000 gal. Key assumptions included: (1) secondary
quality effluent, (2) 40 days' equalizing storage, (3) solid
set sprinklers at 98-foot by 70-foot settings, and (4) trans-
mission for 1 mile by pumping against 200 feet of head.
The capital costs were amortized over 20 years at 6 percent
interest. Discounting the land cost of $140 per acre,
the estimated capital cost for transmission and distribu-
tion amounted to $2,700 per acre.
For spray sites visited the costs were: $800 per acre (in
1968) for the solid set system at Idaho Supreme; $1,500 per
acre (in 1966) for golf course irrigation at Moulton-Niguel
in California; and $140 per acre (in 1968) for a center
pivot rig at Portales, New Mexico.
The cost of increased pumping head must be compared with
the cost of different pipe sizes to obtain the most econom-
ical solution for the design flow. The costs of pumping
stations versus flow for an ENRCC index of 1860 (March 1973)
are shown on Figure 12. These costs are general in nature;
local manufacturers should be contacted for more exact
costs.
The cost of piping for transmission to the site will vary
with the amount of pipe ordered, type of pipe, and shipping
distance. As with the pump costs, local manufacturers
should be contacted for price information.
Distribution piping costs versus effective distribution
diameter for square, rectangular, and triangular settings
are shown on Figure 13. Effective distribution diameter is
the wetted diameter for a single sprinkler. Again, these
costs are for 1967 in Pennsylvania, and local contacts
should be made for pipe prices. Sprinkler heads vary
from $3 to $15 each, depending on the type and complexity.
Reported costs for construction of ridge and furrow systems
and flood irrigation systems are sparse. They are gener-
ally much lower than spray irrigation costs except when
extensive earthwork is involved. At Westby, Wisconsin, a
ridge and furrow system was carved into a 5 percent slope
using four terraces. The cost, including earthwork, piping,
and pumping, was about $2,500 per acre. On the other hand,
when the flow is by gravity, the costs can be very low.
Reported costs for .the ridge and furrow system at Mount
Vernon Sanitary District, California, in 1956 were $75 per
acre, which included leveling, preparation, and fertilizing
of the 1,000 acres [78]. Schraufnagel [105] reported
144
-------
ENRCC INDEX = 1860
600
400
o 200
100
-
2C
0. I
0 2
-PACKAGE PUMPING
STATION «AX
HEAD 150 FT
CONCRETE PUMPING
STATIONS. MAX
HEAD 150 FT
0.4 06081 2
DESIGN CAPACITY MGO
6 BIO
FIGURE 12
CONSTRUCTION COST OF SEWAGE PUMPING STATIONS
145
-------
2200
1900 -
1600 -
o
t
in
1300 -
1000 -
700 -
400
STPCC INDEX =118
JUNE 1967
SPRINKLER SPACING:
RECTANGULAR
5-IN. DIAM LATERALS
4-IN DIAM LATERALS
3-IN DIAM LATERALS
70 90 110
EFFECTIVE DISTRIBUTION DIAMETER. FT
130
FIGURE 13
DISTRIBUTION PIPE COSTS FOR SPRAY IRRIGATION [ 2 ]
146
-------
ridge and furrow costs of $300 per acre for a Minnesota
creamery in 1950, and $2,000 per acre for a Wisconsin
creamery in 1954.
Operation and Maintenance Costs
Costs for operating and maintaining irrigation systems
depend upon the type and size of the system and the geo-
graphical location. Operating and maintenance costs are
evaluated here for spray, ridge and furrow, and flood irri-
gation systems. Annual budgets for several cities and
industries, gathered in part by APWA, are listed in
Table 27. Annual budgets include operating and maintenance
costs for pretreatment as well as irrigation. The higher
costs for industries are due, in part, to the seasonal
nature of the operation and also to the fact that all in-
dustries listed in Table 27 use spray irrigation. For
example, the Green Giant Company operation at Montgomery,
Minnesota, lasts 100 days, and many other canneries operate
only 60 days per year.
Spray Irrigation For municipalities, operating and main-
tenance costs may range from 2.7 to 11.6^/1,000 gal., as
shown in Table 27. Included are costs for labor, replace-
ment materials, and power.
For industries the literature offers a long and varied list
of costs, reported in various units such as cents per case.
In Minnesota the operating and maintenance cost for a spray
irrigation system in 1953 was 0.6<£ per case [86] . This
waste was from the canning of peas and corn with a waste
flow of 65 gal. per case. Converted to the more general
unit of cents per 1,000 gallons, the cost in 1951 was
9.3(^/1,000 gal. Because canning waste flows vary tremen-
dously within the industry, it is difficult to convert the
other reported costs in the 1950s which ranged from 1 to
5
-------
Table 27. Annual Costs of Operation and
Maintenance for Municipal and Industrial Irrigation Systems
Location
Municipalities
Oceanside, California
St. Charles, Maryland
PleasantOn, California
Colorado Springs, Colorado
Hphrata, Washington
ankarsficld, California
Ely, Nevada
San Aufiislo, Texas
Calabisas, California
Flow
rate,
ngd
1.
0.
1.
5.
0.
12.
1.
S.
3.
5
S
3
5
4
3
5
0
0
Pre-
trcatjj Type of
ment application
S
0
S
T
0
P
S
P
S
Spraying
Spraying
Spraying
Spraying
Spraying
Ridge and
furrow
Flooding
Flooding
Spraying
Annual budget,
$
63
15
35
137
5
216
22
54
30
,700
,500
,000
,700
,000
,000
,000
,000
,000
Annual cost,
tf/1,000 gal.
11
S
7
6
6
-------
and $2,100 for consulting services. Irrigation with waste-
water was done only prior to the growing season; well water
was used during the growing season. The crop produced an
income of $20,000 to help offset the costs [62].
For municipalities, Bakersfield, California, has an oper-
ating cost of 4.8
-------
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
discussion.
Capital Costs
Capital cost items include land, earthwork, pretreatment,
transmission, distribution, and collection.
Land Land costs for an overland flow site could be cheaper
because sloping land can be utilized. As mentioned under
"Irrigation," the cost of land is strictly dependent on
local conditions. Land slopes up to 12 percent have been
used at Paris, Texas. Land costs for the 500-acre site
at Paris varied from $50 to $600 per acre [21] .
Earthwork The amount of land grooming will vary from site,
to site. The land should have a uniform slope with no low
spots for ponding. Collection ditches can be placed trav-
ersing the sloping land to carry off the surface water.
Construction costs for Paris, Texas, were $1,006 per acre:
$362 for clearing land, $108 for grass cover, $348 for the
piping system, and $188 for miscellaneous work [21].
About one-half of the construction cost of the Hunt-Wesson
system at Davis, California, was for earthwork. This
amounted to approximately $1,500 per acre because the land
was nearly flat prior to construction.
Pretreatment The pretreatment required by the overland
flow system at Paris, Texas, consists of fine screening and
grease removal. The sprinkler system must be protected
from clogging, or maintenance costs will increase.
Transmission and Distribution The requirement for sloping
ground with sprinklers necessitates pumping of the effluent.
The piping for the overland flow system will be basically
the same as for a spray irrigation site. Figure 12 may be
consulted for cost data.
The piping system for Paris, Texas, cost $348 per acre to
install [21] . The cost for piping at the Hunt-Wesson plant
at Davis, California, was about 40 percent of the total
construction cost.
Collection The collection of surface runoff should be in-
cluded in the earthwork costs. Ditches are constructed
150
-------
across the slope to intercept the surface flow. For sites
that require little earthwork, the ditches will be a major
part of the earthwork cost. For the Hunt-Wesson plant at
Davis, the collection ditches were about 10 percent of the
earthwork cost, or about $50,000 for 320 acres.
Operation and Maintenance Costs
Data on overland flow facilities are scarce because of the
limited number of overland flow sites in operation. At the
Paris, Texas, site of the Campbell Soup Company plant, the
annual operational cost is 5^/1,000 gal. The operational
cost is reduced slightly by the income of 0.4^/1,000 gal.
from crops produced on the site. For Hunt-Wesson at Davis,
California, the annual cost is approximately 5 to
10{/1,000 gal.
Management Management costs will vary with the size of
the operation. A small site may require only part-time
labor, while a larger site, such as at Hunt-Wesson, Davis,
will require a full-time operator and maintenance man plus
part-time help. Salaries for operators typically range
from $3.50 to $7.00 per hour. The amount.charged for part-
time operation will be in direct relation to the actual
amount of time spent at the site. Labor costs may amount
to about 50 percent of the annual operating cost.
Additional costs will be laboratory fees for analyses made
on water samples. The extent of the monitoring program
will dictate the laboratory fees.
Maintenance Sprinklers and pumps will require routine
maintenance, and the ground must be checked for erosion.
Hay, which requires cutting, is grown at the Paris, Texas,
site. In 1968, three cuttings were made and the hay was
sold to local cattlemen [21].
Typical costs for maintenance may range from 1 to 2^/1,000
gal. This covers routine maintenance of pumps, distribution
systems, and ground or field cleanup. Costs for replacement
of worn out or broken items of equipment will be in addition
to those for daily maintenance.
Power Power costs for sites will be set by the rate ob-
tained from local power companies. Better rates can be
obtained for an industrial or municipal site than for a
small, private operation.
The power costs for a spray distribution system with pumps
supplying the pressure will run 10 percent to 25 percent of
the total annual cost. The cost will vary with the flow
151
-------
quantity and discharge pressure required. Costs reported
in the literature vary from 1.3 to 2.0<|:/hp-hr of operation.
The approximate cost of power can be calculated from the
pump efficiency, pump horsepower, and local power rates.
Additional power requirements for lighting and other needs
will be small in comparison with those for pumping.
INFILTRATION-PERCOLATION
Capital and operating costs for infiltration-percolation
systems will generally be less than those for irrigation or
overland flow because smaller areas of land are used and
distribution is usually by gravity flow. For high rate
systems, however, pretreatment needs are substantially
greater for infiltration-percolation than for irrigation or
overland flow.
Capital Costs
Capital cost items include land, earthwork, pretreatment,
transmission, distribution, and recovery. Pretreatment and
recovery will generally involve the largest costs.
Land Land for infiltration-percolation sites is generally
in sand and gravel areas, in or near river flood plains.
The largest area found in use was the 40 acres at Hemet,
California. At Westby, Wisconsin, the land cost $750 per
acre in 1958. At Phoenix, Arizona, land for expansion of
the 2-acre Flushing Meadows project might cost as much as
$2,000 per acre.
Earthwork Earthwork required at an infiltration-
percolation site will include construction of the basins
and grading of the beds. Some sites have placed 6 inches
of pea gravel over the beds to retard plant growth, and
this will cost an additional amount to spread. The dikes
generally involve the bulk of the earthwork.
The earthwork costs for the basins at Flushing Meadows were
about $1,500 per basin. The total construction costs per
basin were about $1,800. It should be noted that these
were experimental basins and therefore costs were relatively
high.
Pretreatment The wastewater spread on an infiltration
basin should be fairly free of solids that would clog the
surface and reduce the infiltration rate. At Flushing
Meadows a sedimentation basin was constructed to capture
solids present in the activated sludge effluent.
152
-------
At Whittier Narrows, an activated sludge treatment plant
was built to pretreat the wastewater. Costs of conventional
treatment are listed in Table 26.
Treatment and Distribution - At Flushing Meadows, Arizona,
and Whittier Narrows, California, transmission and distri-
bution are by gravity flow. At Santee, California, the
wastewater is pumped to the site and distributed by gravity
flow.
Transmission pipe costs can be taken from Figure 12. The
distribution canals for Flushing Meadows cost $98,000 but
were concrete lined. The lining accounts for 98 percent of
the cost of the canals. The cost of the transmission and
distribution systems was about 50 percent of the construc-
tion cost.
Recovery A recovery system may or may not be a part of an
infiltration-percolation site. The groundi^ater recharge
systems at Long Island, New York, and at Hemet, California,
are used to create a hydraulic barrier to salt water
intrusion.
Sites at Whittier Narrows and Santee have recovery systems
to reclaim the water. The recovery systems consist of wells
which pump a mixture of reclaimed water and groundwater to
where it is used. At Santee the water is used for recrea-
tion facilities; at Whittier Narrows, the reclaimed water
is sold to groundwater users.
The cost of wells is shown on Figure 14. This is a gen-
eralized graph and not an illustration of absolute figures.
The cost of wells planned at Flushing Meadows is $35 per
foot. Eight are to be constructed 200 feet deep for a cost
of $56,000. Pumps for the wells are estimated to be $17,500
each, or $140,000. The total cost is estimated to be
$196,000 [19].
A recovery system is not necessary for the recharge
facility. Existing privately owned wells nearby could
benefit from the recharge operation and pay for the water
pumped.
Operation and Maintenance Costs
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
-------
600
500 -
1QO-FT
DEPTH
STPCC INDEX =119
JUNE 1367
400 -
300
200
ISO
1000
2000 3000
COST, DOLLARS
4000
5000
FIGURE 14
COSTS FOR RECOVERY WELLS [2]
154
-------
Labor requirements at Flushing Meadows are 80 man-hours per
week for an 0.5-mgd system, but again this reflects the re-
search that was being conducted. At Westby, Wisconsin,
with a flow rate of 0.2 mgd, labor is less than 20 man-
hours per week.
Simpson Lee Paper Company operates two pulp and paper waste
disposal systems by infiltration-percolation. At Kalamazoo,
Michigan, 7 in./day is applied by spraying and at Vicksburg,
Michigan, 1 in./day is applied by spraying. At Kalamazoo
the operating cost is 2.6
-------
Table 28. Comparison of Capital
and Operating Costs for 1-mgd Spray Irrigation,
Overland Flow, and Infiltration-Percolation Systems
Cost item
Liquid loading rate, in./wTc
Land used, acres
Land required, acres
Capital costs
Land 3 SSOO/acre
Earthwork
Pumping station
Transmission
Distribution
Collection
Total capital costs
Capital cost per
purchased acre
Amortized costc
Capital cost,
-------
Land
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
typical.
Earthwork
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 $1,000 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
From Figure 12, a 1-mgd package pumping, station would cost
$50,000 for both the spray irrigation and overland flow
cases. It was assumed that the wastewater could be trans-
mitted to the site by gravity flow; therefore, no pumping
stations for distribution were included for infiltration-
percolation.
Transmission
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.
Distribution
For spray irrigation use was made of Figure 13. An effec-
tive diameter of 100 feet for square spacing was chosen
using 4-inch laterals. The resultant cost per acre of
$850 was increased from STPCC index 118 to 192, and the
cost per acre in 1973 dollars is $1,400.
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.
157
-------
Collection
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 $3,000
each for 1967 conditions. Updating the well costs to 1973
dollars and adding $15,000 for recovery pumps, the cost for
collection became $30,000.
Operation and Maintenance
Labor requirements were expected to be one man, full-time,
for spray irrigation and overland flow. A single man oper-
ating three-fourths of the time was necessary for
infiltration-pereolation.
Maintenance costs were calculated as 10 percent of the
capital costs of pumping stations, distribution, and
collection. Power costs \vere variable, but were expected
to be 2
-------
SECTION IX
LAND APPLICATION POTENTIAL
Many benefits as well as limitations involved in land appli-
cation have been discussed in this report. In this section
the intent is to place both limitations and positive aspects
of land application in perspective and to attempt to analyze
the future potential of the various methods. The first
part of the discussion deals with municipal wastewater;
the second part deals with industrial wastewater.
MUNICIPAL WASTEWATER
Land application of municipal wastewater in this country
has been done mainly by irrigation, to a lesser extent by
infiltration-percolation, and not at all by overland flow.
The limitations and benefits of each approach are different
and will be discussed separately.
In comparing the three approaches to land application it is
helpful to define the objectives to be achieved with treated
wastewater and to observe the response of each approach
in realizing those objectives. In Table 29 a list of
objectives has been assembled and the ability of each
approach to realize those objectives is tabulated. As
can be seen, each approach has several potentialities as
well as limitations. In addition to considerations of man-
agement objectives, an analysis of land application must
include considerations of the Federal Water Pollution
Control Act Amendments of 1972.
Federal Amendments of 1972
Land application was given a substantial role in the Federal
Amendments of 1972 to implement the "national goal that dis-
charge of pollutants into navigable waters be eliminated
by 1985." Section 201 (b) of the Act stipulates that:
(b) Waste treatment management plans and prac-
tices shall provide for the application of
159
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Table 29. Comparison of Irrigation, Overland
Flow, and Infiltration-Percolation for
Municipal Wastewater
Objective
Use as a treatment process with
a recovery of renovated water
Use for treatment beyond
secondary:
1. For BOD and suspended
solids removal
2. For nitrogen removal
3. For phosphorus removal
Use to grow crops for sale
Use as direct recycle to
the land
Use to recharge grounduater
Use in cold climates
Irri gat ion
Impractical
90-9'.)°.
Up to 90ta
80-991
Excellent
Complete
0--30',
Fair b
Type of approach
Overland t'low
SO to 60',
recovery
90 -;)
-------
Thus, land application must be considered as an alternative
to conventional and advanced wastewater treatment in the
prevention of surface water pollution.
Irrigation
The benefits of irrigation are many: economic return on
the sale of crops; saving of potable water supplies through
exchange by irrigating landscapes, golf courses, parks, and
highway medians with wastewater; fire protection by hill-
side spraying (especially in California [141]); and serving
as a positive and reliable alternative to advanced waste
treatment and/or surface water discharge. The latter
benefit applies to most land application methods.
As shown in Section VIII, economic benefits from the sale
of crops have been substantial in some cases. Operating
costs are low due to the relative simplicity of operation.
Irrigation with municipal wastewater may be allied with the
need for open space and green belts in urban and suburban
areas. The Golden Gate Park wastewater reclamation plant
in San Francisco, California, has been-producing 1 mgd
of water for this purpose for the last 40 years [70, 48,
73]. Irrigated lands have also been leased for recreational
purposes such as duck hunting in the fall. In Section
201(f) of the 1972 Federal Amendments it is stipulated that
"waste treatment management which combines open space and
recreational considerations with such management" shall be
encouraged.
Several limitations to irrigation have been mentioned in
this report. The principal ones are the considerable
land area required, its relatively high cost, and its
relatively long distance away from large urban sources of
wastewater. In climatic Zones A and B in moderate-sized
cities near agricultural areas, the practice is quite
feasible, and many cities have followed this approach. In
climatic Zones C, D, and E the need for irrigation water is
less and agricultural land has considerable value without
irrigation; therefore, the practice requires other
motivations. At Muskegon, Michigan, where nearly 10,000
acres will be irrigated, the need was for an economic
and feasible alternative to surface water disposal [34].
Limitations to spray irrigation for health reasons are less
severe. Adequately disinfected wastewater should pose no
danger to health when it is sprayed. Aerosols for spraying
should be kept from traveling as heavy mist outside of the
irrigation tract by rows of trees or buffer zones. Any
aerosolizing of inadequately disinfected municipal
161
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wastewater, be it in an activated sludge plant, a river
outfall, or in a spray field, produces some risk to human
health, and these risks should all be minimized. Sprinklers
that spray downward or horizontally, especially with low
nozzle pressure, adequate disinfection, and buffer zones
all function to increase the safeguards.
Overland Flow
Overland flow is subject to the same types of limitations
as irrigation, but it can be done with a relatively im-
permeable soil and a gently sloping terrain. These latter
two factors may combine to yield a land site of moderate
cost. In general, suitable sites will be as difficult
to find within economic transmission distances of cities
as they are for irrigation.
Overland flow has considerable potential for treatment of
municipal wastewater. At Ada, Oklahoma, comminuted munici-
pal wastewater has been sprayed at low pressures in an ex-
perimental system at a loading rate of about 4 in./wk.
The results show an effluent 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 climates.
Overland flow has the advantages of avoiding groundwater
degradation, of providing economic return through the growth
and sale of hay, and providing a high quality effluent suit-
able for many additional reuse applications. As indicated
in Table 29, it cannot be used as a complete direct recycle
of wastewater to the land. However, the runoff will be of
high quality and can be directly recycled by any other land
application approach.
Infiltration-Percolation
Benefits from infiltration-percolation of municipal waste-
water include (1) an economic alternative to surface water
discharge, (2) a treatment system with nearly complete re-
covery of renovated water possible, and (3) 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.
162
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The major limitations of the process are in connection with
groundwater effects. The fact that influent nitrogen is
converted to the nitrate form, which is leached to the
groundwater, is of major concern. If the groundwater zone
becomes anaerobic, conversion of sulfates to hydrogen sul-
fide may also be a problem.
Nitrates can be a problem (1) if the groundwater is reused
for potable supply, (2) if the groundwater is reused for
recreation lakes, and (3) if the groundwater is reused for
unrestricted irrigation.
These problems are (in the order mentioned) related to
(1) causing methemoglobinemia in children, (2) eutrophica-
tion, and (3) overstimulation of crops, such as grapes, in
which nitrate nitrogen concentrations above 30 mg/L are
reported to cause abundant growths of foliage at the ex-
pense of fruit production.
At Flushing Meadows, Arizona, research and operational
changes have been aimed at increasing the nitrogen removal
of their high rate system. Further research needs to be
conducted on this subject.
Less critical limitations include the following: (1) phos-
phorus retention 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 renovation; and (3) the groundwater aquifer re-
ceiving the water needs to be monitored and controlled
for high rate systems to prevent groundwater degradation.
INDUSTRIAL WASTEWATER
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 utilized land application ex-
tensively, such diverse industries as tanneries [91] and
chemical plants [140] have used land application
successfully. In general, for plants located in rural or
semirural areas that produce wastewaters with mainly organic
contents, land application offers great potential. For
industries producing toxic or high inorganic content waste-
waters, land application probably offers small promise.
There are so-many modifications and combinations of land
application methods that could be used for any given indus-
trial wastewater, that no sweeping limitations can be
stated solely on the basis of a type of industry.
163
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In general, industries are more able than municipalities to
include new technology in their wastewater management plans,
which partially explains their use of the overland flow
approach. Industries have allowed the soil matrix to pro-
vide a greater amount of treatment than have municipalities
and have tended to search out the limits of loading for
soil systems. With this approach it is likely that new
improvements or modifications to the common methods will
continue to come from industries as well as from soil
scientists and researchers.
164
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SECTION X
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103. Rudolfs, W. , Falk, L.L., and Ragotzkie, R.A., "Contam-
ination of Vegetables Grown in Polluted Soil: VI.
Application of Results," Sewage 5 Industrial Wastes,
23, pp 992-1000 (1951) .
173
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104. Sanitary Engineering Research Laboratory, "Studies in
Water Reclamation," Technical Bulletin No. 13, Univer-
sity of California, Berkeley (July 1955).
105. Schraufnagel, F.H., "Ridge-and-Furrow Irrigation for.
Industrial Wastes Disposal," Jour. WPCF, 34, No. 11,
pp 1117-1132 (1962).
106. 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).
107. Scott, R.H., "Disposal of High Organic Content Wastes
on Land," Jour. WPCF, 3_4, No. 9, pp 932-950 (1962).
108. Sepp, E., "Disposal of Domestic Wastewater by Hillside
Sprays," ASCE Env. Engr. Div. , 9£, No. EE2, pp 109-121
(1973).
109. Sepp, E., "Nitrogen Cycle in Groundwater," Bureau of
Sanitary Engineering, Calif. State Dept. of Public
Health, Berkeley (1970).
110. Sepp, E., "Survey of Sewage Disposal by Hillside
Sprays," Bureau of Sanitary Engineering, Calif. State
Dept. of Public Health, Berkeley (March 1965).
111. Sepp, E., "The Use of Sewage for IrrigationA
Literature Review," Bureau of Sanitary Engineering,
Calif. State Dept. of Public Health (1971).
112. Skulte, B.P., "Agricultural Values of Sewage,"
Sewage S Industrial Wastes, 25_, No. 11, pp 1297-1303
(1953).
113. Skulte, B.P., "Irrigation with Sewage Effluents,"
Sewage § Industrial Wastes, 2£, No. 1, pp 36-43 (1956).
114. Smith, R., "Cost of Conventional and Advanced Treatment
of Wastewater," Jour. WPCF, 40., No. 9, pp 1546-1574
(1968).
115. "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) .
116. Sokolik, N.I., "The Effect of Irrigation on the Heat
Regime of Surrounding Areas," Glavn. Geofizich.
Observatorii Im. A.I. Voeikova: Trudy, vypusk 77,
pp 34-42 (1958), Translated by G.S. Mitchell, Office
of Climatology, U.S. Army Elect. Prov. Gd., Ft.
Huachuca (1961) .
174
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117." 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).
118. "Sprinkler Irrigation," Chapter 11 in Irrigation,
Section 15 of SCS National Engineering Handbook, Soil
Conservation Service, U.S. Dept. of Agriculture (July
1968).
119. "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) .
120. Sullivan, D., "Wastewater for Golf Course Irrigation,"
Water 5 Sewage Works, 117, No. 5, pp 153-159 (1970).
121. Tchobanoglous, G., "Physical and Chemical Processes
for Nitrogen Removal - Theory and Application,"
Proceedings of the 12th Sanitary Engineering Con-
ference, University of Illinois, Urbana,Illinois
(1970) .
122. "The Cost of Clean Water, Vol. Ill, Industrial Waste
Profiles No. 6 - Canned and Frozen Fruits and Vege-
tables," FWPCA, U.S. Dept. of the Interior, Contract
No. 14-12-101 (September 1967).
123. Thomas, R.E., and Bendixen, T.W., "Degradation of
Wastewater Organics in Soil," Jour. WPCF, 41, No. 5,
Part 1, pp 808-813 (1969) .
124. 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).
125. 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).
126. Thomas, R.E., Schwartz, W.A., and Bendixen, T.W.,
"Soil Chemical Changes and Infiltration Rate Reduction
Under Sewage Spreading," Soil Science Society of
America, Proceedings , 50, pp 641-646 (1966) .
127. Thornthwaite, C.W., "An Approach Toward a Rational
Classification of Climates," Geographical Review,
38_f No. 1, pp 55-94 (1948) .
175
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128. Thornthwaite, C.W., and Mather, J.R., "The Water
Balance," Publications in Climatology, Laboratory of
Climatology, 8^ No. 1 (1955).
129. Urie, D.H., "Phosphorus and Nitrate Levels in Ground-
water as Related to Irrigation of Jack Pine with
Sewage Effluent," 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).
130. U.S. Salinity Laboratory, Diagnosis and Improvement
of Saline and Alkali Soils, Agriculture Handbook No.
60, U.S. Dept. of Agriculture (1963).
131. van der Goot, H.A., "Water Reclamation Experiments at
Hyperion," Sewage § Industrial Wastes, 29, No. 10,
pp 1139-1144 (1957).
132. Vendrov, S.L., and Malik, L.K., "An Attempt to Determine
the Influence of Large Reservoirs on Local Climates,"
Soviet Geography: Review and Translation, 6_, No. 10,
pp 25-40 (1965).
133. "Wastewater Management by Disposal on the Land," Corps
of Engineers, U.S. Army, Special Report 171, Cold
Regions Research and Engineering Laboratory, Hanover,
N.H. (May 1972) .
134. "Waste-water Renovation by Spreading Treated Sewage for
Ground-water Recharge--Abstracted from the Annual
Report," U.S. Water Conservation Laboratory, U.S.
Dept. of Agriculture, Phoenix, Arizona (1971).
135. Water Resources Engineers, Inc., "Cannery Waste Treat-
ment, Utilization, and Disposal," California State Water
Resources Control Board, Publication No. 39 (1968).
136. Wells, D,M., "Groundwater Recharge with Treated Muni-
cipal Effluent," Proceedings of the Symposium on
Municipal Sewage Effluent for Irrigation, Louisiana
Polytechnic Institution (July 1968).
137. Wentink, G.R., and Etzel, J.E., "Removal of Metal Ions
by Soil," Jour. WPCF, 44_, No. 8, pp 1561-1574 (1972).
138. Wesner, G.M., and Baier, D.C., "Injection of Reclaimed
Wastewater into Confined Aquifers," Jour. AWWA, 62,
No. 3, pp 203-210 (1970).
176
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139. 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).
140. Woodley, R.A., "Spray Irrigation of Organic Chemical
Wastes," Proceedings of the 23rd Industrial Waste
Conference^Purdue University, Lafayette, Indiana,
pp 251-261 (1968) .
141. Younger, V.B., "Ecological and Physiological Implica-
tions of Greenbelt Irrigation with Reclaimed Water,"
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).
142. Zimmerman, J.P., Irrigation, John Wiley $ Sons, Inc.,
New York (1966).
177
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SECTION XI
PUBLICATIONS
1. Pound, C.E., and Crites, R.W., "Nationwide Ex-
periences 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
1973).
178
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SECTION XII
GLOSSARY OF TERMS, ABBREVIATIONS, SYMBOLS,
AND CONVERSION FACTORS
TERMS
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 b~F selected constituents present in
wastewater after secondary treatment.
Alkali soil--A soil with a high degree of alkalinity (pH of
W,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~Trahsmits it from one point to another in quantities
sufficient to permit economic development.
Border strip method--Application of water over the surface
of the soil.Water is applied at the upper end of the long,
relatively narrow strip.
Consumptive use--Synonymous with eyapotranspiration.
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.
179
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Effective precipitation--Precipitation that enters the soil
and is useful for plant growth.
Evapotranspiration--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 areaTotal 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.
FloodingA 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-
urated zone 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
withdrawals.
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.
Irrigation--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
applied 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.
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Micronutrient--A chemical element necessary in only small
amounts (less than 1 mg/L) for microorganism and plant
growth.
Mineralization--The conversion of an element from an or-
ganic form to an inorganic form as a result of microbial
decomposition.
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
diseases.
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^oi^- -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.
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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
allthe information necessary for their own reproduction.
Wetted area--Area within the spray diameter of the
sprinklers.
ABBREVIATIONS
acre-ft--acre-foot
BOD --biochemical oxygen demand
BODS --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
1S2
-------
hr --hour
hp-hr --horsepower-hour
in --inch
kw --kilowatt
Ib --pound
m --meter
max --maximum
mgd --million gallons per day
rag/L --milligrams per liter
mi --mile
min --minute
ml --milliliter
mm --millimeter
mo --month
mph --miles per hour
MPN --most probable numbet
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)
IDS --total dissolved solids
wk --week
yr --year
183
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SYMBOLS
B --boron
Ca --calcium
Cu --copper
K --potassium
Fe --iron
Mg --magnesium
Mn --manganese
N --nitrogen
Na --sodium
NH- --ammonia
NO., --nitrate
P --phosphorus
S --sulfur
Zn --zinc
> --greater than
< --less than
y --micro
CONVERSION FACTORS
million gallons x 3.06 = acre-feet
acre-inch x 27,154 = gallons
mg/L x ft/yr x 2.7 = Ib/acre/yr
184
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SECTION XIII
APPENDICES
APPENDIX A. SITE VISIT SUMMARIES
Sites Visited During Study
Abilene, Texas
Moulton- Miguel Water District,
California
Portales, New Mexico
San Francisco, California
Woodland, California
Lake George, New York
Phoenix, Arizona
Westby, Wisconsin
Idaho Supreme Potato Company,
Firth, Idaho
Beardmore § Co, Limited,
Acton, Ontario, Canada
Sites Visited Prior to Study
Hakersf ield, California
Mount Vernon Sanitary District,
California
Campbell Soup Company,
Chestertown, Maryland
Campbell Soup Company,
Napoleon, Ohio
Campbell Soup Company,
Paris, Texas
Hunt-Wesson Foods, Inc.,
Davis, California
California Canners 5 Growers,
Thornton, California
Campbell Soup Company,
Sumter> South Carolina
Seabrook Farms Company,
Seabrook, New Jersey
Sebastopol, California
Tri/Valley Growers, Stockton,
California
Sites Visited by APWA
APPENDIX B. HISTORICAL CASES OF IRRIGATION
ABANDONMENT
Inquiry Design
Inquiry Results
California Sites
Texas Sites
185
185
185
188
189
190
192
193
195
198
199
200
217
217
218
218
219
221
224
225
226
227
232
232
233
242
242
242
242
247
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APPENDIX A
SITE VISIT SUMMARIES
Data from many existing sites were used in the preparation
of this report. Visits were made to 9 selected sites in
the United States and 1 in Canada. Data from 11 sites
were collected during previous studies for specific clients.
In addition, through cooperation with APWA, data from 63
cities and 19 industries were analyzed. Besides visiting
sites APWA conducted a mail survey which netted infor-
mation on an additional 78 cities and 36 industries.
SITES VISITED DURING STUDY
The 9 sites visited in the United States were: (1) Abilene,
Texas; (2) Moulton-Niguel Water District, California;
(3) Portales, New Mexico; (4) San Francisco, California;
(5) Woodland, California; (6) Lake George, New York;
(7) Phoenix, Arizona; (8) Westby, Wisconsin; and (9) Idaho
Supreme Potato Company at Firth, Idaho. The first 5 sites
involve irrigation with treated municipal wastewater;
sites 6 through 8 involve infiltration-percolation with
treated municipal wastewater; and site 9 involves spray
irrigation of treated industrial wastewater. A spray irri-
gation site for industrial wastewater was also visited at
Acton, Ontario. The descriptions of these visits are pre-
sented in this appendix in the sequence listed. Following
the descriptions are the tabulations showing the actual
data (Table 30).
Abi_lene, Texas
Effluent from a 9.0-mgd activated sludge plant is used for
summer irrigation. Approximately 4.5 mgd is applied at a
rate of about 3 in./wk by border strip irrigation.
History In the early 1920s when the city of Abilene was
quite small, the sewage disposal system was composed of a
septic tank and subsurface drainage field. As the city
grew, oxidation ponds were added to take care of excess
185
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liquids until 1926, when the system was moved to a new loca-
tion about 5 miles northeast of the existing city. Six
hundred and forty acres of land were purchased at that time,
and more land was purchased in 1927, bringing the total
acreage to 1,224 acres. Oxidation ponds and lagoons were
constructed at the new location to provide some treatment.
The effluent from the oxidation ponds was released to
farmers in the immediate area to be used for irrigation
purposes. This lagoon system remained in use until 1958.
As the system was located on Lake Fort Phantom Hill water-
shed, the City could not qualify for State-approved water
until the sewage irrigation system was moved. The City
found a new location some 4 miles northeast of the old dis-
posal area completely off the Phantom Hill watershed. Lake
Fort Phantom Hill is Abilene's main source of water supply,
having a capacity of 73,000 acre-feet.
In 1960 the City purchased 2,019 acres of land for the
treatment plant and irrigation system. Features of that
primary plant included grit removal, sedimentation, oxida-
tion ponds, sludge digestion, and holding ponds. There are
40 acres of oxidation ponds and 375 acres of holding ponds
with a capacity of 600 million gallons. The new sewer plant
is located in Jones and Shackelford counties, in the Hamby
Flat area, which is some of the best farming land in the
Abilene area. Naturally, the thought of locating a treat-
ment plant in that area was very unpopular with the farmers
in the surrounding area. Actually, the Hamby area was
about the only location that could be found that would be
suitable for a disposal plant and still be located off the
Abilene lake's watershed.
Lawsuits The plant had been in operation only a short
time when numerous complaints and protests were made by
citizens from the immediate area about the creation of
odors, mosquitoes, the seepage from the farm, and the crea-
tion of a general nuisance. From January 15, 1960, through
June 12, 1963, 30 suits were filed against the City of
Abilene, amounting to $1,500,000. The first five suits
amounted to $164,800. These suits were tried by jury, and
the plaintiffs were awarded $147,165. All of the suits
were tried in out-of-county courts, but all of the suits
were appealed to a higher court. While the lawsuits were
going on, the City forces were busy correcting things that
could be corrected, and improving where improvements were
feasible. The years of 1960 and 1961 were very wet years,
and there was a limited area (1,620 acres) on which to dis-
pose of the sewage effluent. At times the whole farm was
one large lake. Seepage from the farm was water-logging
farmers in the surrounding areas. More than 4 million gal-
lons of seepage water was entering Deadman Creek each day.
186
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Deadman Creek flows around the farm and the farm is on the
Deadman Creek watershed. Odors were bad in the area around
the farm, because of the high load of BOD in the oxidation
ponds and lagoons. The raw sewage entering the plant had
an average BOD of 650 ppm in 1961. Also, because of the
long distance the sewage had to travel to reach the plant,
it became very septic. At that time, the City of Abilene
did not have an Industrial Waste Ordinance, and a strong
inorganic substance in the sewage was killing the algae
growth in the oxidation ponds, which in turn increased the
odors. Since the Industrial Waste Ordinance was passed in
1961, the BOD load has decreased from 650 ppm to about
250 ppm in 1964.
Many things were done to reduce odors and improve condi-
tions in the farm area. The raw sewage was chlorinated
about midway from town to the treatment plant. A perimeter
ditch was dug around the farm to intercept sewage that was
seeping from the farm and discharge it to Deadman Creek.
At the present time, all the lawsuits have been settled.
The $1,500,000 in lawsuits were settled for $200,000. While
the laivsuits were being tried the citizens of Abilene voted
bonds to build a complete secondary sewage treatment plant.
It is now in operation discharging 4.5 mgd in the summertime
to Deadman Creek.
New Sewage Treatment Plant In 1963, the City built a
12-mgd activated sludge plant. The aeration system is by
submerged diffusers which are tapered from the head end to
the discharge end of the plug flow tanks. The effluent is
chlorinated with approximately 7 ppm to maintain a residua^
of 2 ppm in the effluent after 1 hour. The effluent can bo
discharged to Deadman Creek, the holding ponds, or to the
irrigation system.
Irrigation System The system consists of buried pipeline
to the various user farms. In the settlement of several of
the suits in the early 1960s, contracts were signed to
supply 2,640 acre-feet of water annually to 5 different
users. In additon, 1,554 acres of the original farm are
leased to farmers and supplied with 24 acre-inches per acre
annually. Mr. Martinez leases 1,400 acres for $17,000 per
year or about $12 per acre. Land cost is about $300 per
acre.
Since the average rainfall is 23 inches per year, the farm-
ers only need irrigation water at certain times from May to
September. A typical application rate is 6 in./day flooded
on by border strip irrigation followed by 10 to 14 days of
resting. The soil is a drainable loam underlain by pockets
187
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of sand and gravel but generally underlain by caliche
(hardpan). The caliche and gravel are underlain by
limestone. Groundwater reaching the pockets of sand and
gravel will move laterally and emerge as seepage water.
Crops grown include maize, cotton, wheat, and coastal ber-
muda grass. Cattle are grazed on the fields after harvest-
ing of the maize. There are also three houses on the City's
farm.
The treatment and disposal operations appear to be going
smoothly. Mean annual effluent BOD is about 11 mg/L which
is well below the discharge requirement of 20 mg/L. The
operator indicated that his main problem in the effluent
has been grease (discharged from packing houses). The cost
for treatment of the wastewater prior to irrigation is
7^/1,000 gal.
Moulton-Niguel Water District, California
This water district operates 3 wastewater reclamation plants
in Orange County, in southern California. Reclaimed waste -
water is used for golf course irrigation. All 3 plants
have activated sludge treatment.
Plant No. 1A -. This 400,000-gpd plant produces irrigation
water for the 160-acre El Niguel Golf Course. The applica-
tion rate is light at 1 in./wk, although the bermuda grass
fairways need as much as 2 in./wk during the months of July
through September. In November the flow from the plant is
bypassed to the South Laguna sewage treatment plant as only
the greens are irrigated over the winter months.
The soil of the golf course fairways is an adobe clay while
the material for the greens is imported sandy loam. The
course has a rolling terrain and a large proportion of the
irrigated water runs off into small creeks and ultimately
to Salt Creek and the ocean. The groundwater does not
interfere with the operation.
After being treated by the activated sludge process, the
effluent is discharged to 4 ponds in series. The first
pond is aerated by three floating aerators while the other
3 ponds (1 acre each) are polishing ponds. The effluent
is chlorinated and pumped to the golf course. Effluent re-
quirements are: BOD and suspended solids, less than 30
mg/L; coliform organisms, MPN less than 2.2 per 100 ml; and
incremental increase in TDS less than 300 mg/L.
The golf course management contracts for 350 acre-feet per
year from Moulton-Niguel Water District at $1 per acre-foot.
188
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It supplements this reclaimed water with MWD (Metropolitan
Water District of Los Angeles) water which costs $52 per
acre-foot. The annual cost of water to El Niguel Golf
Course is $26,000.
Plant No. 2A - This 250,000-gpd plant discharges to 3 ponds
presently used for percolation and evaporation. Future
plans are to build recreational lakes and fill them with
effluent.
Plant No. 5A - The largest of the 3 plants, this activated
sludge plant has a capacity of 0.75 mgd, but normally pro-
duces 0.4 to 0.5 mgd for the irrigation of the 160-acre
Mission Viejo Golf Course. In a manner similar to El Niguel
Golf Course, Mission Viejo appropriates water from the
Moulton-Niguel Water District at $1 acre-foot and from MWD
at $52 per acre-foot. The annual cost of water for Mission
Viejo is $14,000. This is nearly half of what El Niguel
pays because the Moulton-Niguel Water District can supply
the full 350 acre-feet per year to the golf course.
Secondary effluent is piped 0.9 mile under the San Diego
Freeway to a holding pond. When effluent BOD exceeds 30
mg/L, the rapid sand filters are used as tertiary treatment
prior to chlorination. A second chlorination station is at
the effluent pumps from the holding pond. A combined
residual of greater than 1.0 mg/L is maintained at the
pumps so that a trace residual can be held at the farthest
point in the spray system to prevent odors of sewage. In
addition to maintaining a coliform count of less than 2.2
per 100 ml, a regulation restricts watering within 50 feet
of public buildings with reclaimed water.
In the summer the golf course uses up to 1.25 mgd of water
and in the winter as little as 0.1 mgd. When fairway irri-
gation is discontinued, the wastewater from the Moulton-
Niguel plants goes to the South Laguna sewage treatment
plant.
Portales, New Mexico
Effluent from a trickling filter plant is used to irrigate
alfalfa and cotton. Spray, ridge and furrow, and border
strip irrigation methods are used to apply the 1-mgd flow
to the land.
History - Portales had a sewage farm in the 1930s. Regula-
tions against irrigation with raw sewage forced the con-
struction of an Imhoff tank in 1935. In 1942 a primary
plant was built and upgraded with trickling filters in 1952.
189
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In the 1950s the City's farm was converted to a sanitary
landfill. A ditch was constructed several miles to a
marshy area known as a "salt lake." A farmer along the
route, Mr. Gonzales, began diverting summer flows for irri-
gation of cotton and alfalfa in about 1962. In 1968,
Roger Patterson and Gordon Hatch built a 35 acre-foot hold-
ing pond, installed a pump, and began to spray irrigate 120
acres of alfalfa. The City does not own any of the land
presently irrigated.
Operation The trickling filters are overloaded and conse-
quently the influent BOD of 280 mg/L is reduced to only
about 100 mg/L. The holding pond is serving as an anaerobic
lagoon and there is no chlorination of effluent. The spray
irrigation system has priority over the 1.0 mgd of effluent,
and sprinkling takes place at a rate of 2 in./day, one day
per week for the 8-month growing season. The excess efflu-
ent is used by Mr. Gonzales as it flows by gravity past his
property. He flood irrigates his 20 acres of alfalfa using
the border strip method and irrigates 20 acres of cotton by
the ridge and furrow method. The soil on both farms is a
sandy loam with some alkali. The Patterson farm is so
sandy that previously the land was not irrigated. The sys-
tem now used is a center pivot rig, about 1,320 feet long
with iron wheels. The cost in 1968 was approximately
$17,000. The system operates automatically with a low pres-
sure shutoff and seems to be a successful application.
Because water is scarce the application rate is only in-
tended to meet the needs of the crops.
Future Plans An aerated lagoon followed by polishing
ponds and sand filters for a flow of 2.0 mgd is being de-
signed by Ralph Vail of Santa Fe. The plant will replace
the existing works and provide effluent to meet the State
requirement on effluent of 125 mg/L COD, 30 mg/L BOD, and
0.05 ml/L settleable solids. No standards have been set on
effluent coliform levels. No changes in effluent disposal
are anticipated.
San Francisco, California
The Golden Gate Park Water Reclamation plant in San
Francisco produces up to 1 mgd of reclaimed water to irri-
gate park lawns and shrubbery. The activated sludge plant
effluent is chlorinated and mixed with well water prior to
application by sprinkling.
History When the park was built in the 1870s,. under the
direction of Mr. McLaren, there was no adequate water sup-
ply source» He developed two well fields and diverted
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untreated sewage from the Lincoln Avenue sewer to a septic
tank. He used the combined well water and septic tank
effluent to irrigate the western half of the park.
In 1931 a suit was brought that forced the abandonment of
the septic tank. A 1-mgd activated sludge plant was de-
signed by Gilman Hyde for the McQueen Sewage Treatment
Company and built near Elk Glen Lake. The effluent served
as irrigation water, along with the well water, for the
western part of the park until 1947. At that time a pump-
ing plant was built at Elk Glen Lake to serve the eastern
part of the park also,
Water Reclamation Plant - The water reclamation plant, put
into operation in 1932, is a conventional activated sludge
plant without sludge treatment. Wastewater is diverted
from the Lincoln Avenue sewer, through a sand trap, a bar
screen, a flash aeration basin, and into a rectangular pri-
mary sedimentation tank. Primary sludge, grit, and screen-
ings are returned to the sewer that connects to the
Richmond-Sunset plant. Primary effluent is aerated by
diffused aeration in tanks that are 10 feet deep. The
tanks are compartmentalized by vertical baffles into 10
bays. Because the aeration diffusers are at a depth of 3.'5
feet, spiral flow throughout the depth is not accomplished.
After 5 bays, the mixed liquor is transferred to the second
bank of 5 bays, but the connection is near the water sur-
face and consequently most of the solids are retained in
the first 5 bays. The effluent from the No. 10 bay flows
into the secondary settling tanks from which all the sludge
is recirculated. The effluent is chlorinated at a dosage
of 18 to 28 mg/L with a chlorine contact time of 1.5 hours.
The operation is completely manual and requires 3 men during
the day and 1 man at night. Wasting of mixed liquor is
from the aeration tank, and the decision to waste and the
volume wasted is determined daily from experience, taking
into account flow, mixed liquor suspended solids, dissolved
oxygen content in the No. 10 bay, and the form of effluent
nitrogen. The air supplied to the second 5 bays is half of
.that supplied to the first 5 bays so that there is tapered
aeration.
The final effluent quality is surprisingly good with sus-
pended solids around 10 mg/L and coliform organisms, MPN
less than 2.2/100 ml. The effluent form of nitrogen is
mostly ammonia although nitrification occurs periodically.
In early 1972 the effluent suspended solids began to in-
crease, and the mixed liquor suspended solids were reduced
from 1,200 mg/L to 200 to 300 mg/L. The chief operator
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suspects that the composition of the sewage is changing be-
cause of the activity of several research hospitals in the
area.
Irrigation System About 800 acres of the park are irri-
gated by fixed sprinklers supplemented by hand sprinkling.
Irrigation is usually required from April to October, but
in some years irrigation has been required until December.
The water reclamation plant generally operates from mid-
February until November and produces about one-third of the
water for irrigation of the 800 acres. Irrigation usually
lasts for 1.5 to 3 hours with an application of about 1
inch of water. The resting period is usually 6 days. The
calculated loading rate for this sandy soil is 3,750 gad
or about 1 in./wk.
The groundwater does not interfere with the irrigation
practice, and no test wells have been drilled. The well
field in the western part of the park is declining with
only 3 of the original 7 wells still producing.
Woodland, Cali f o r n i a
The municipal and industrial wastewater treatment ponds at
Woodland produce up to 8.7 mgd for crop irrigation.
History Sewage farming in Woodland began in 1889 with the
irrigation of hay and pasture land east of town. In 1905
the resultant odors led to a lawsuit that forced the sewage
farm to be moved. From 1905 to 1930 farming with sewage
continued in a larger tract east of the original plot. The
City has purchased additional land over the years so that
it now owns over 1,400 acres.
In 1948 a primary sewage treatment plant was constructed on
Beamer Street, and the effluent is used for irrigation.
The City has built numerous ponds since that time, and now
all treatment except coarse screening is accomplished in
oxidation ponds.
The present municipal waste flow is 4.2 mgd, and the sepa-
rate tomato canning waste averages 4.5 mgd from mid-July to
October. Near the abandoned primary plant a series of ponds
provides the equivalent of primary plus secondary treatment
for 0.3 mgd which is then percolated into the ground. The
remainder of the wastewater is treated in ponds and is made
available for irrigation.
Irrigation System - The irrigation ditch runs eastward to a
site near Tule Canal in the flood plain of the Yolo bypass.
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The City owns 430 acres which is presently leased to
Mr. C. W. Plumb. Mr. Plumb owns and irrigates 240 acres of
milo north of the City's land. This year he raised saf-
flower (a nonirrigated crop) on the City's 430 acres. He
pays the City $10,000 per year for the land and has the
right to the treated effluent when he needs it. On the 240
acres of milo he applied 30 inches of water per season at a
rate of about 1.5 in./wk. The water is applied by flooding
and the runoff is collected in a drainage ditch which dis-
charges into Tule Canal.
The Regional Water Quality Control Board's requirements for
discharge to Tule Canal are a minimum of 60 days' detention
prior to discharge and a dissolved oxygen content of 5.0
mg/L in Tule Canal. When water is not needed for irriga-
tion, the 430 acres are flooded and leased as a duck hunt-
ing area. Parts of the 320 acres of industrial waste
treatment ponds are also leased for duck hunting.
Mr. Hiatt, the Public Works Director, has a good deal of
experience with wastewater ponds, and the result is a well
operated system. The system is flexible enough to handle
breakdowns at any critical point by overflowing to another
treatment pond.
Lake George, New York
The Village of Lake George disposes of trickling filter
effluent by infiltration-percolation. The treatment plant
is located 1 mile from the south shore of Lake George, which
is 36 miles long and from 1 to 3 miles wide.
Lake George Village Sewage Treatment Plant - The Village
sewage treatment plant receives wastewater from 5 pumping
stations, including 2 located in the Town of Lake George.
The winter flow rate 'is 0.3 mgd, and the summer flow rate
averages 1.2 mgd. Primary treatment is provided by 2 cir-
cular Clarigesters (similar to Imhoff tanks) built in 1965
and an Imhoff tank built in 1936, all operating in parallel.
During winter the Imhoff tank is taken off line. The pri-
mary effluent passes over 2 trickling filters built in 1939
and receives secondary settling. Clarified secondary efflu-
ent is piped to 21 separate percolation beds. There are no
chlorination facilities. Sludge from the secondary settling
tanks is returned to the Clarigesters, and digested sludge
.is disposed of on sand drying beds. The plant capacity is
1.75 mgd. The only problem with the operation is the peak
flow delivered from the Town, which overloads the Clari-
gesters and results in solids carryover. An equalization
basin is planned to remedy this problem.
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Percolation Beds There are 21 percolation beds, each with
an area of 0.5 acre. The beds have 3- to 5-foot dikes
around them, and each bed has a control valve for individ-
ual flooding. Each morning the valve is opened on a new
bed, which is flooded with 8 to 10 inches of effluent over
the next 9 hours. When the operators leave in the evening
the next bed is put on line.
During winter the liquid loading ranges from 7 to 15 in./wk.
After the 9-hour flooding the beds are rested for 5 to 10
days. When the solids on the surface are dried out, they
are scraped off and the bed is ready for the next
application. When ice forms on the surface, it is not re-
moved but merely floated by the next application of
effluent.
In the summer, more than 2 beds are flooded each day, but
4 to 5 days are still allowed for resting. The average
loading is 15 in./wk. The material in the beds ranges from
coarse to fine sand, with a few beds having some clay
content. Wells have been driven down 56 feet without
running into bedrock or the permanent water table. No vege-
tation grows in the beds because of the weekly scraping of
the surface. There have been no serious problems with the
operation of the percolation beds.
Environmental Effects Mr. Harold Gordon, the Plant Super-
intendent, indicated that the State of New York was con-
cerned about phosphorus buildup at the south end of Lake
George due, in part, to the leaching of phosphorus through
the beds and into the lake. Dr. Donald B. Aulenbach of the
Environmental Engineering Division at Rensselaer Polytechnic
Institute has conducted several studies in regard to en-
vironmental effects of the Lake George Village percolation
beds. The results of his studies have shown a buildup of
nitrates at the 10-foot depth in the beds from an initial
2 mg/L to 8 mg/L, and a phosphorus increase, in one bed,
from an initial 25 to 27 mg/L. In a second, less-used bed,
the phosphorus removal was 60 percent in 10 feet. Ten feet
of sand were found to remove 100 percent of the organic
nitrogen, 99 percent of the coliforms, and 96 percent of
the BOD. Total nitrogen removal was about 40 percent.
Dr. Aulenbach also found that a mound of water was created
by the percolation operation. After dosing one bed (No.
11)' continuously for 2 weeks, the bed was saturated with
water to a depth of 10 feet, but was no longer saturated at
15 feet. This bed was considered a "fast bed" in that the
water percolated away in a day or two. Bed No. 13, which
showed a 72 percent phosphorus removal in 5 feet, was only
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slightly used because its control valve was located in a
manhole that is difficult to reach.
Dr. Aulenbach is currently planning field studies to verify
the movement of effluent through the sand and ultimately
into the lake. Resistivity studies have indicated a nat-
ural pathway from the beds to the lake which he plans to
verify by drilling wells and sampling the groundwater. A
student under Dr. Aulenbach has run effluent through sand
in the laboratory, under conditions 'similar to those in
the field, until the phsophorus uptake capacity was reached.
When this occurred, he dosed the columns with distilled
water, simulating rainfall, which leached the phosphorus
from the sand. The results and conclusions of this study
have not been published.
Ph p en i x , Ajr i z on a
The Flushing Meadows project near Phoenix, Arizona, is a
pilot infiltration-percolation system for wastewater
renovation. It is conducted under the direction of Dr.
Herman Bouwer, Director of the U.S. Water Conservation
Laboratory. IVastewater for the study is activated sludge
effluent from the 91st Avenue plant.
History In the Phoenix area, one-third of the agricultural
water comes from groundwater. The remaining two-thirds of
the irrigation water and the municipal supplies are obtained
from surface reservoirs on the Salt and Verde rivers. In
recent years the groundwater table in the Phoenix area has
been dropping 10 ft/yr. In 1971 the water table dropped
20 feet. The depth to groundwater varies from 400 feet in
the Mesa area to 50 feet near the Salt River in the Phoenix
area.
Fl_ush_injT Meadows Project In 1967 the Flushing Meadows
Project was begun. THe~~ob j ectives were to study the treat-
ment of sewage effluent by rapid infiltration and determine
infiltration rates. Specifically, the removals of BOD,
suspended solids, nitrogen, fluoride, and pathogenic orga-
nisms were important. It was desired to obtain renovated
water of a quality sufficiently high to permit unrestricted
irrigation.
A site was located west of Phoenix within the flood plain
of the Salt River. The 2-acre site was divided into 6
basins that are 20 feet wide and 700 feet long. The soil
is a sandy loam made up of 2 to 3 percent clay, 50 percent
silt, and 47 percent sand. Infiltration rates of 1 ft/day,
or 350 ft/yr, are regularly achieved by flooding for 14 days
and resting 10 to 20 days. During the 2 weeks of inundation
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(surcharge is about 1 foot) the infiltration rate drops
from 2.5 ft/day to 1.5 ft/day, with an average of 2 ft/day
During the summer, 10 days are sufficient for drying, re-
aeration, and biological oxidation which restores the
infiltration capacity, but winter operation requires 20
days.
Four of the beds are planted with grass. (Sudan grass,
common and Giant bermuda grass, and rice have been used.)
One bed is natural soil and one has been covered with
4 inches of 3/8-inch gravel overlying a 2-inch layer of
coarse sand. At both ends of each bed is a critical
depth flume and a liquid level recorder. The difference
between the two recorders indicates the infiltration rate
in the basin. At the outfall end of each basin a level
control device maintains a predetermined depth of water
and permits rapid drainage of the water when necessary.
Numerous test wells are located within the treatment
area, two are 100 feet away from the area, one is 250
feet away, and a final one is 300 feet away. Most wells
are 20 feet deep, but one is 30, one is 100, and one is
250 feet deep. After 3 years of operation, treated
water had not reached the well that is 300 feet away.
Treated water is identified from native groundwater by its
low salt content.
The permeability of the soil using well water is 4 ft/day.
The groundwater table is at a depth of 10 feet. Removals
were: BOD, fecal coliform, and suspended solids, essen-
tially complete; phosphorus and fluoride, 70 percent;
nitrogen, 30 percent; and boron, lead, and cadmium, essen-
tially zero.
23rd Avenue Project The City of Phoenix has been awarded
a grant from the EPA for a project near the 23rd Avenue
sewage treatment plant. This project would involve rapid
infiltration of 15 mgd on 40 acres, followed by pumping
of the renovated water into a nearby irrigation canal.
The wastewater would have secondary treatment with acti-
vated sludge at the 23rd Avenue plant. Because the efflu-
ent suspended solids concentration is above 50 mg/L, a
holding reservoir for sedimentation will be provided prior
to infiltration. The existing 40-acre oxidation pond will
be drained and divided into 4 parallel basins, with wells
along the central median to recover the renovated water.
The water table at this location is at a depth of 50 feet.
If this project proves successful, a third stage project
would be built utilizing secondary effluent from the 91st
Avenue wastewater treatment plant. This plant has a capac
ity of 60 mgd and is presently treating 72 mgd, or 80,000
acre-ft/yr. . The City of Phoenix has an agreement with the
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Buckeye Irrigation District that the City will allow, Buckeye
to use 28,000 acre-ft/yr of effluent. In exchange, Buckeye
will not press claims to an equivalent volume of water it
claims was lost to the District because of upstream opera-
tions by the City,
The secondary effluent flows in a channel westward past the
Flushing Meadows Project (where 0.6 mgd is used as influent)
and on 20 miles to the Buckeye Irrigation District. The
average water use for irrigation in the area is 4.5 acre-
ft/acre/yr. Because of the agreement between the City and
Buckeye, the District does not publicly admit irrigating
with sewage effluent, and Dr. Bouwer felt that a contact
with Buckeye Irrigation District would be fruitless.
Rio Salado Project This is another reclamation project
proposed for the Mesa-Tempe area. The effluent from Mesa's
5-mgd trickling filter plant flows into the dry Salt River
bed and infiltrates within a half-mile of the plant. The
project would involve drilling a well to recover the water,
building a flood control channel, and establishing a green-
belt area along the Salt River.
Nitrogen Studies In addition to the' field studies con-
ducted by the Water Conservation Laboratory, laboratory
studies have been conducted specifically aimed at determin-
ing nitrogen removal mechanisms. These studies have been
conducted primarily by Dr. J. Clarence Lance. Dr. Lance
discussed his studies and supplied copies of his publica-
tions on the subject.
It has been found that ammonia nitrogen in the sewage efflu-
ent is absorbed in the soil within the top 3 feet during
inundation. During resting periods the bacteria in the
soil oxidize ammonia to nitrate which frees the absorption
sites. When inundation begins again, anaerobic conditions
quickly prevail and some denitrification occurs; however,
because of the high rate of infiltration, a slug of nitrate
is flushed into the groundwater. Using the laboratory soil
columns, Dr. Lance has determined that a 30 percent reduc-
tion of total nitrogen occurs. If the slug of high nitrate
can be recycled, the overall nitrogen removal would be
80 percent.
After a long period of 14 days on, 10 days off, the ability
of the soil to absorb ammonia decreases. At this point a
change in cycle to 2 days on and 5 days off stimulates the
nitrifiers and rejuvenates the ability of the soil to absorb
ammonia. During this cycle denitrification essentially
ceases.
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Westby, Wisconsin
The system at Westby is a ridge and furrow infiltration-
percolation operation. Trickling filter effluent from an
0.2-mgd plant is pumped up to the basins for disposal.
Physical System The system consists of 8 terraced basins
covering 6 acres. The basins are 70 feet wide and 460 feet
long, and they have been cut into a natural hillside having
a slope of about 5 percent. The furrows are approximately
16 inches wide and 9 inches deep. The ridges are 35 inches
wide and planted to Reed canary grass. The grass is not
cut, but is burned each spring before new growth starts.
The system was built in 1959 with an area of 3.7 acres.
The silt loam soil is underlain by limestone rock at 14 to
18 feet. A comprehensive study in 1964 noted that percola-
tion rates in the virgin soil were on the order of 10
ft/day, but that the system had lost a major part of its
original infiltration capacity. The loading rate in 1964
was 11.2 in./wk, and the present loading is 8.4 in./wk.
The last 2 basins were added in 1971, but the infiltration
rate in them is low because of the presence of limestone
and the lack of a cover crop. Since 1970 the system has
been overloaded. The grass planted in the last 2 basins
did not grow because the basins had to be placed into ser-
vice too soon. The past 12 months (March 1972 to March
1973) have been extremely wet, and it is likely that all of
the grass has been drowned out. In March 1973, all basins
were standing in 1 to 3 feet of water.
Wastewater Characteristics A two-stage trickling filter
Ts used to treat approximately 0.2 mgd of primarily domes-
tic wastewater. A locker plant and a small butter packing
plant are in the municipal system, but the large Westby
Cooperative Creamery has a separate waste disposal system.
The removal efficiency of the plant in terms of BOD is 72
percent at a loading of about 4,000 Ib/acre-ft/day.
Although both filters are being overloaded there are no
odor problems. There are summertime problems with filter
flies, but use of an insecticide controls the propagation.
There are no chlorination facilities. Under peak flow con-
ditions or during times of mechanical breakdown, the waste-
water can be bypassed into'a dry drainage ditch. Originally
(1947 to 1959), effluent was discharged to this ditch, but
threatened,litigation from landowners because of the odors
produced ended this practice and led to the irrigation
system.
Operation The normal operation of the ridge and furrow
system in the mid-1960s was to apply wastewater to 2 basins
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for a week and then dry for a week. During periods of high
flow this drying period was reduced. In March 1973 the
entire flow went to one basin per day with a resting period
of 6 to 7 days. As a result of heavy rains over the past
18 months and increased wastewater flows, however, this
resting period is inadequate and water stands in each basin,
In the summer months mosquitoes may propagate in standing
water; however, the insecticide used to control filter
flies seems to control mosquitoes in the fields also. Dur-
ing winter the flow continues to the basins as there is no
separate storage. Observations in some winters indicate
that a bridge of ice supported by the ridges would develop
over the furrows and that a channel for flow of wastewater
was maintained in the furrows. In more severe winters the
entire mass of water will freeze causing random channeling
of the applied wastewater across the basin. It should be
mentioned that grading of the basins was far from perfect,
resulting in imperfect distribution.
Future Plans A new contact stabilization activated sludge
plant with a capacity of 0.325 mgd has been designed for
Westby by Davy Engineering Co. of La Crosse, Wisconsin.
Although the City owns 40 acres of land, in addition to the
8 acres presently used for treatment and disposal, the
plans call for effluent discharge to a polishing pond and
thence to the drainage ditch. According to percolation
tests on the 40 acres, an application rate of 10,000 gad
would be excessive. Apparently the depth of soil cover
over the limestone is as shallow as 2 feet in some areas.
Idaho Supreme Potato Company, Fi/rth, Idaho
This potato processing wastewater is spray irrigated for
treatment and disposal. Dr. Jay Smith, of the U.S. Depart-
ment of Agriculture, is conducting a 3-year study on
environmental effects. The average flow is 630,000 gpd
which is applied to 80 acres by spraying at a rate of 0.29
in./day or 2 in./wk. Another 110 acres of land are avail-
able for flood irrigation. In 1971, with 50 acres of spray
field, the application rate averaged 3.25 in./wk, and odor
complaints were received.
The spray system, installed at a cost of $800 per acre,
consists of solid set sprinklers spaced on 80-foot squares
discharging at 80 to 100 psi. Nozzle sizes for the rocker
jet sprinklers are 9/32 inch by 5/32 inch. All distribu-
tion piping is made of polyvinylchloride.
The soil is silty loam from the Snake River flood plain,
underlain by sand and gravel. Because of the operation and
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nearby irrigation canals, the groundwater rises from below
20 feet to within 2 or 3 feet of the surface. In areas
where this interferes with the sprinkling, the manager re-
duces the length of the normally 12-hour sprinkling period
or skips that 5-1/2 acre plot for an irrigation cycle. The
average rest period for each plot is 16 to 18 days in win-
ter, when the sprinkling period is 24 hours, and 8 to 9
days in summer.
Two waste\vater streams come from the processing plant:
"silt water" from potato washing, and "white water" from
potato peeling and cutting. Vacuum filters are used on
silt water with the mud going to a lagoon and the filtrate
to the spray field. Rotating drum screens are used on the
white water with the solids reclaimed for cattle feed and
the screened wastewater settled, combined with the filtrate,
and pumped to the spray field.
Dr. Smith will monitor the quality changes in the soil and
groundwater over the next 3 years as at Idaho Fresh Pak.
Preliminary samples from a 4-foot depth collected by Jerry
Hastings, Plant Manager, indicate complete removals of COD
and suspended solids and 70 percent removal of total
nitrogen.
The fields were planted to a mixture of Reed canary grass,
meadow foxtail, and alta fescue, but the fescue has not
done well. The yield of hay is 5 tons/acre. Total precipi-
tation is 7 in./yr (rain and snow). Normal irrigation in
the area is 6.5 feet in 110 days of growing season versus
8 feet in 330 days at Idaho Supreme.
Beardmore § Co., Limited, Acton, Ontario, Canada
Tannery wastewater is applied to the land by spray and
ridge and furrow methods for infiltration-percolation.
History Beardmore § Co., Limited, is old and stately.
Their offices and grounds reflect a long history of profit-
able business, as well as a deep appreciation of quiet
conservatism. With this in mind it is not surprising that
their land treatment system dates back to 1951 when virtu-
ally nothing of value had been published. It is also
characteristic that they would select a very capable engi-
neer, Mr. R. R. Parker (now retired), to apply himself to
the problem with only his own ingenuity to draw upon. As
a result, the Beardmore system differs from other systems
in a number of ways. At the outset Parker's only reference
was a breezy article in Newsweek which described the
"Bottomless Forest" at Seabrook Farms.
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The Beardmore effluent is tannery waste which ranges in pH
from 4.5 to 10.5. It is notable that the high pH is from
calcium hydroxide rather than sodium, but since the hides
from the abattoir are packed in salt, chlorides have now
become a problem. The BOD loading, which is largely of
vegetable origin, ranges between 800 and 3,000 mg/L while
the water volume averages 1.25 mgd.
At the outset Mr. Parker was also confused by the then pop-
ular concept that water, instead of solids, was the problem
and he set about to evaporate it by spraying. Unfortu-
nately, there are no records, but the venture failed anyway.
He next tried woods irrigation in an attempt to emulate
Thornthwaite's success at Seabrook. Here he achieved a
partial success but became alarmed when the trees began to
die and abandoned the project. This he attributed to
toxicity of the effluent, but it is more likely that the
exclusion of oxygen from the aeration zone of the roots was
the actual cause. He then moved his giant sprinklers
(250 gpm) to a grass covered area and again had problems.
Apparently the line pressure supplying the sprinklers was
not consistent, and the impact upon the soil of the un-
broken stream of water caused severe-erosion damage.
Although Mr. Parker continued to favor the use of large
nozzles for the obvious reasons of simplicity and economy,
he was forced to abandon them and the eventual system began
to emerge at this point. The nozzle now in use is very
small--about 4.5 gpm.
For many years prior to the irrigation era, wastewater was
stored in' large lagoons for settling before being dis-
charged to the receiving stream. No one knows for certain,
but it is believed that this practice has been going on for
50 years or more. As a result, sediment has built up in
the large lagoons to a depth of about 30 feet. Disposal
of these solids was another problem which confronted
Mr. Parker and more recently Mr. Greifeneder--his successor.
The Present Situation - The effluent from the Beardmore
plant is now segregated into two waste streams, one with
high BOD and low pH (3,000 mg/L and 4.5, respectively) and
the other with low BOD (800 mg/L) and high pH. After
screening, both streams are stored in winter but the second
stream is aerated before storage. Both streams go directly
to treatment in summer with the low concentration going to
spray irrigation and the "black water" to a ridge and furrow
treatment area. The low pH of the black water is caused by
organic acids while the high pH of the larger stream is
caused by calcium hydroxide, part of which converts to
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calcium carbonate. This stream also contains most of the
salt.
There are roughly 200 acres in the whole operation, about
half of which are in the spray field, but the company is
running out of land for storage. Accordingly, there is a
massive operation underway to clean the storage lagoons of
accumulated sludge. The sludge has been dewatered by de-
hydration to the point where it will support a man's weight
on the surface, but underneath it is still soft. To compli-
cate matters further, the stumps of large trees which once
grew on the bottom of the lagoons were not removed and now
impede the cleaning operation.
The ridge and furrow installation is not unusual, but the
flume to distribute the water is. A watertight trough
about 1 square foot in cross section extends along the
top of the field. The flume has gates in the bottom which
can be opened to direct water into the various furrow
channels. It is believed that this ridge and furrow system
is a carryover from Mr. Parker's early experience when he
discovered that trees were killed by the heavily loaded
effluent. In any event, there is no attempt to grow vege-
tation on this field, and the land is disked and reshaped
every year. Apparently there have been no runoff or ground-
water problems which would lead to the suspicion that the
material is not toxic at all.
In the spray system, surface piping is used--polyethylene,
rather than aluminum. Sprinklers are spaced at 30 feet,
and the field is covered in a solid set pattern. The
attachment of the sprinklers is unique. Instead of a tee,
a bronze tapped saddle is used to tap the lateral line.
On the bottom of the saddle an 8-inch spike has been brazed
to the clamp, and the threaded outlet faces upward. Thus,
when the spike is pushed into the ground, the sprinkler is
automatically vertical. The sprinklers are screwed into
the saddle without a riser.
During the first few years of operation there were odor
complaints when the water in the lagoon went septic follow-
ing the spring turnover. At first, masking agents were
used, but later the stored water was sprayed first and in
high volume, at a rate of 2 in./day and 360 Ib BOD/acre/day,
Spraying is begun as soon as the grass begins to green and
continues nonstop until all of the stored water is
distributed. Later the application is reduced to 0.46
in./day and 83 Ib BOD/acre/day. During some of his early
experience Mr. Parker applied up to 600 Ib BOD/day for 30
days continuously without adverse effect.
202
-------
Grass management by Beardmore is unique and effective. The
company learned early that legumes--clover and alfalfa--
could not survive and, with the advice of the Canadian
Department of Agriculture, they worked out a mixture of
hydrophytic species. These survived for a few years but
were gradually replaced by Twitch Grass--normally consid-
ered a weed. Although the fields produced hay of good
quality, the cost of harvest and disposal did not justify
the return. After many false starts, a hammer mill type
mower was selected, and weekly mowing now keeps the grass
to a height of 2 to 5 inches. The cuttings are not col-
lected, and there has been no detrimental effect, except
that each field is out of service for about 30 days per
year. With so much reserve capacity, however, this is not
a problem. The Beardmore installation is the only known
system to maintain such close control of grass.
The cost of the Beardmore system is high, and the operating
cost is even higher. Mr. Parker reported a capital cost of
$2,000 per acre about the same as a solid set buried sys-
tem with automatic controls. The operating cost is more
than double that of Seabrook Farms, which handles ten times
the gallonage. It should be pointed''out that such figures
are seldom reliable since no two companies use the same
cost accounting system. For example, Beardmore may be
redistributing executive management cost to all operations
while Seabrook does not.
The experience of Beardmore with winter operation parallels
that of many other companies and contradicts as many more.
They believe that whenever the temperature drops to 20
deg F for several days, the spraying season is over. They
avoid the buildup of ice on the soil in the belief that
vegetation is injured, and storage for 5 months in lagoons
is provided. By contrast, at Seabrook, ice mounds are
created deliberately during freezing weather in order to
store water. There has never been damage to the vegetation
Throughout northern United States, managers of spray sys-
tems argue this point endlessly with neither side giving
ground.
Another unique experience at Beardmore is noteworthy. As
mentioned above, the installation relies upon infiltration
and percolation, and will handle a very respectable
2 in./day. However, the exaggerated claims for Seabrook in
t}ie Newsweek article made it appear that 2 inches was not
sufficient. In order to improve the percolation rate,
underdrains were installed in a 1/2-acre plot at a depth of
6 feet. The discharge from these pipes was erratic in
quality, ranging from 10 to 300 mg/L BOD. Quite obviously
203
-------
there was a short-circuit somewhere, but they were never
able to find it and the project was abandoned.
Recently the company has encountered stiff opposition from
the pollution control authorities who object to the chloride
discharge. As mentioned previously, the hides have been
salted at the abattoir when received, and this salt is re-
moved during tanning. At times the salt content of the
water reaches 3,300 mg/L--500 mg/L is usually accepted as
the threshold of taste. There was considerable concern
originally that the high SAR--30--would cause "puddling" of
the soil (i.e., dispersion of the crumb structure as sodium
replaced calcium on the soil micelles). However, these
reactions are always on a mass balance basis, and when a
sufficient number of calcium ions are present the exchange
does not take place. In this case about 1 ton of calcium
carbonate per acre per year is normally contained in the
wastewater, and this is sufficient to keep the sodium moving
along as sodium chloride.
While this leaching process is great for the spray fields
it is not so good for the groundwater, and there has been
much pother because of increased chlorides in water wells.
Chlorides are always a problem for industries which use
salt in their process because there is no easy way to re-
move them from wastewater. For a small company like
Beardmore the only practical solution for handling chlorides
is by dilution, and this they have done by locating the
spray field far away from dwellings and water wells. Re-
cently, ho\*ever, a developer constructed homes close to the
Beardmore property, and the residents complained about the
chloride content of the drinking water. To put this into
perspective one must be aware that the U.S. Public Health
limitation for drinking water is 250 mg/L, while the water
from the wells in question was only 120 mg/L. Nevertheless,
Beardmore was forced to give up 30 acres that were formerly
used and to construct a 2-mile pipeline to supply the resi-
dents with city water.
This problem appears to have no end, and the existence of
the company is threatened. Within the regulatory group are
a number of young idealists who have allegedly produced
medical evidence that chlorides produce heart disease. The
residents involved are led to believe that if they drink
the water they will die. There appears to be no way to
stop this scare-mongering and to put the problem in proper
perspective. However, a practical limit to future restric-
tions may be established by the fact that the city sewerage
system discharges 100 mg/L of chlorides, a major portion of
which is present in the fresh water supply. The city,
incidentally, is a bedroom community with no large industry
except Beardmore.
204
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Table 30. Detailed Data on Land
Application Sites Visited for This Study
Facility name
Abilene, Texas
Moul ton -Miguel
Type of
wastewater
Municipal
Municipal
Pretreatment
Activated sludge,
effluent chlori-
nation
Activated sludge ,
Average
flow, mgd
4.5
O.S
Year
started
1920
1966
WD, California
Portales,
Mew Mexico
San Francisco,
Cali fornia
Woodland,
Cali fornia
Lake George,
New York
Phoenix,
Ari zona
Westby,
Wi scons in
Idaho Supreme
Potato Co.,
Tirth, Idaho
Beardmore 5 Co.
Ltd., Acton,
Ontario,
Canada
tertiary filtra-
tion, effluent
chlorination
Municipal Trickling filters 1-0
Municipal Activated sludge, 1.0
effluent chlori-
nation
50°s municipal Oxidation ponds
50 °0 canning
8.7
Municipal
Municipal
Municipal
Potato
processing
Tannery
Trickling filters 1. 2r
0.3°
Activated sludge 0.67
Trickling filters
Screens
0.63
Screens, aeration 1.25
1935
1932
1889
1936
1967
1959
1969
1951
a. Summer.
H. Winter
205
-------
Table 30 (Continued)
Facility name
Abilene, Texas
Mo ul ton-Ni guel
WI), California
Port. -lies ,
New Mexico
San Francisco,
C;i 1 i fornia
IVoocll and ,
Ca 1 i fornia
Lake George ,
New York
Phoenix ,
Ari zona
Wcstby ,
Wi scons in
Idalio Supreme
Used
2,019
163
160
1,000
1,400
10.5
2
6
80
Area, acres
Irrigation Buffer Unused
1,550
160 50 ft 14
160
800 -- 200
240
. .
_ _
6
80 -- 110
Storage
400
3
3
1.2
120
Potato Co.,
Firth, Idaho
Beardmore § Co.
Ltd., Acton
On tario,
Canada
400
100
35
200
25
206
-------
Table 30 (Continued)
Facility name
Abilene, Texas
Moulton-Niguel
WD, California
Portales ,
New Mexico
San Francisco,
Call fornia
Woodland ,
Call fornia
Lake George ,
New York
Phoenix,
Arizona
Westby ,
Wisconsin
Idaho Supreme
Months
used
5
7
8
7
6
12
12
12
12
Volume of
storage, Method of
acre-ft application
1 ,850 Border strip
25 Spray
35 Spray, ridge
and furrow,
flooding
6 Sp r ay
1 ,660 Flooding ,
ridge and
furrow
Spreading
Spreading
Ridge and
furrow
Spray
Application
rate ,
in. /day
6
1
2
1
3
8-10a
8b
24
1.2
5
Potato Co.,
birth, Idaho
Beardmorc $ Co.
Ltd., Acton,
Ontario,
Canada
300
Spray , ridge 0.5
and furrow
a. Summer.
b, Winter.
207
-------
Table 30 (Continued)
Facility name
Idaho Supreme
Potato Co.,
Firth, Idaho
Bcardmore 5 Co.
Ltd., Acton,
Ontari o,
Canada
Organic Nitrogen
Liquid Annual loading loading
Drying loading liquid rate, rate,
period, rate, load, Ib BOD/ Ib NY
days in./wk ft/yr acre/yr acre/yr
Abilene, Texas
Moult on - N'i gue 1
U'P, California
Portalcs ,
New Mexico
San Francisco,
Cal i fornia
Woodland ,
Ca li fornia
Lake George,
New York
Phoenix ,
Arizona
V.'c.s thy ,
V.'i scons in
10-14
1-2
6
6
12
4- 5a,
5-10b
10-20
14 of
28
3
2
2
1
1.5
30a
7b
84
8.3
2.0
5.0
5.8
2.5
2.5
65
400
36
92
405
1,565
51
284
6,800
10,800
3,200
65
108
337
72
2,950
23,800
3,080
16-18
3.5
8.7
11.4 25,000
2,900
a. Summer.
b. Winter.
208
-------
Table 30 (Continued)
Facility name
Abilene, Texas
Moulton-Niguel
V.'D, California
Portales ,
New Mexico
San Francisco,
California
Woodland ,
California
Lake George,
New York
Phoenix,
Ari zona
U'cstby ,
Wisconsin
Soil type
Clay loam
Clay
Sandy loam
Sand
Clay loam
Sand
Sandy loam
Silt loam
Crop
Cotton,
maize ,
coastal
bermuda
grass
Bermuda
grass
Alfalfa,
cotton 3
wheat
Grass
Milo
--
Reed
canary
grass
Geology
Depth to Depth to
impervious ground- Slope
layer, ft water, ft \
<100 14-16 <2
>2
<6
<2
Variable Variable <2
-- 80 < 2
50 40 <2
250 10 <2
14-18 >200 >2
< ft
Tdaho Supreme
Potato Co. ,
Firth , Idaho
Bcardmore 5 Co,
Ltd., Acton,
Ontario,
Canada
Silt loam Grass
Clay loam Grass
3-10
< 2
Variable > 2
< 6
209
-------
Table 30 (Continued)
Facility name
Land,
$/acre
Costs
Annual Year for Annual
operations System capital return,
budget, $ cost, $ costs $
Abilene, Texas
Moulton-Niguel
WD, California
Portales,
New Mexico
San Francisco,
California
Woodland,
California
Lake George,
New York
Phoenix,
Arizona
Westby,
Wiscons in
Idaho Supreme
Potato Co.,
Firth, Idaho
Beardmore § Co.
Ltd., Acton,
Ontario,
Canada
300
221,000
240,000 1966
17,000 1968
<95,000 52,875 1932
100-500 50,000
750
600-800
34,000
10,000 1959
64,000 1969
17,000
350
675
10,000
210
-------
Table 30 (Continued)
Facility name
Abi lene , Texas
Moulton-Niguel
U'D, California
Portales ,
New Mexico
San Francisco,
Cal if ornia
Woodland,
Cal if orn ia
Lake George,
New York
Phoenix ,
Ari zona
W cs tby ,
W is cons in
Climate
Zonec
B
A
B
A
A
E
B
E
BOD, mg/L
To
To ground
land water
17
30
100
5-10
42
30-46 1.5
10-20 0-1
33 4
COD, mg/L
To
To ground
land water
84
79
- -
_ .
30-60 10-20
118 42
Idaho Supreme
Potato Co.,
Fi rth, Idaho
Bcardmorc Fj Co.
Ltd., Acton,
Omar i o,
Canada
1,300-2,800 0
800-3,000
c. As defined in Figure 10.
211
-------
Table 30 (Continued)
Facility name
Abilene, Texas
Moulton-Niguel
WD, California
Portales ,
New Mexico
San Francisco,
California
Woodland,
California
Lake George,
New York
Phoenix,
Arizona
Westby ,
Wisconsin
SS, mg/L pH
To To
To ground To ground
land water land -water
12 -- 7.1
19 -- 7.7
--
5-15
88 -- 9.8
__
50-100 0 7.7-8.1 6.9-7.2
85 -- 7.2
Idaho Supreme
Potato Co.,
Firth, Idaho
Beardmore § Co.
Ltd., Acton
Ontario,
Canada
500
6.8
4.5-10.5
212
-------
Table 30 (Continued)
E.Coli
To
To ground
Facility name land water
Abilene, Texas
Moulton-Niguel 2.2 MPN
WD, California
Portales ,
New Mexico
S;in Francisco, <2.2 MPN
Cali fornia
Woodland, 1.3xl05
Call fornia
Lake George, 970 8
New York
Phoenix, 105-106 0-100
Arizona
Wcstby,
IV is cons in
Total P, mg/L
To
To ground
land water
29
1-10
7.9
25.4 27.5
7-12 4-8
29.5 2
Idaho Supreme
Potato Co.,
Firth, Idaho
Bcardmore § Co.
Ltd., Acton,
Ontario,
Canada
213
-------
Table 30 (Continued)
Facility name
Total N, mg/L
To
To ground
land water
TDS, mg/L
To
land
To
ground
water
Abilene, Texas
Moulton-Niguel
WD, California
Portales,
New Mexico
San Francisco,
California
Woodland,
Callfornia
Lake George,
New York
Phoenj x,
Arizona
Kcstby,
V.'is cons in
12
8
750
1,046
40-60
10.6
16.7 10.5
22-47 S.8-70.7 1,000-1,200 1,000-1,200
31.6 9.4
480
Idaho Supreme
Potato Co.,
Tirth, Idaho
Bcardmore § Co.
Ltd., Acton,
Ontario,
Canada
123
38
3,500-6,000
214
-------
Table 30 (Continued)
Faci1ity name
Alkalinity, mg/L
To
To ground
land water
Sodium, mg/L
To
To ground
land water
AbiJcnc, Texas
Moulton-Niguel
WD, California
Port ales,
New Mexico
San Francisco,
Cali fornia
U'ood 1 and,
Cn 1 i fornia
Lake George,
N'cw York
Phoen ix,
Ari zona
Wcsthy ,
K is irons in
Idaho Supreme
Potato Co.,
I;irth, Idaho
Bcardmore 5 Co.
Ltd. , Acton,
Ontario,
Canada
196
209
192
192
695
200
74
215
-------
Table 30. (Concluded)
Facility name
Abilene, Texas
Moulton-Niguel
WD, California
Portales ,
New Mexico
San Francisco,
California
Woodland ,
California
Lake George,
New York
Phoenix ,
Ar i zona
IVcstby,
Wisconsin
Calcium, mg/L Magnesium, mg/L Potassium, rag/L
To To To
To ground To ground To ground
land water land water land water
17 -- 44 -- 36
99 -- 22 -- 15
82 -- 36 -- 8 --
36 -- 26
Idaho Supreme
Potato Co.,
Firth, Idaho
Beardmore § Co.
Ltd., Acton,
Out ario,
Canada
216
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SITES VISITED PRIOR TO STUDY
In addition to the nine sites in the United States and the
one in Canada visited as a key part of the data collection
activity, 11 sites were visited prior to and apart from the
study. Information on these sites, two of which are munici-
pal and nine of which are industrial, is included here.
The municipal sites, which use irrigation, are Bakersfield,
California, and Mount Vernon Sanitary District, California.
The industrial sites include four overland flow systems and
five spray irrigation systems. The overland flow sites in-
clude three installations for the Campbell Soup Company at
Chestertown, Maryland, Napoleon, Ohio, and Paris, Texas;
and one installation for Hunt-Wesson Foods, Inc., at Davis,
California. The five spray irrigation systems are for
California Canners § Growers, Thornton, California; Campbell
Soup Company, Sumter, South Carolina; Seabrook Farms
Company, Seabrook, New Jersey; Sebastopol, California; and
Tri/Valley Growers, Stockton, California.
Bakersfield, California
Municipal wastewater has been used to irrigate cropland at
Bakersfield since 1912. The City has two primary treatment
plants. Plant No. 1 was built in 1939 and has a capacity
of 5.5 mgd, while Plant No. 2, built in 1952, has a capacity
of 16.0 mgd. The effluent from the plants is blended and
is not disinfected.
The effluent is transmitted to the irrigation site by grav-
ity, and irrigation is primarily by the ridge and furrow
method with some flood irrigation. The present flow of
11.3 mgd is used to irrigate approximately 2,400 acres of
crops, including cotton, corn, barley, alfalfa, and pasture.
The land is leased to a local farmer who controls the plant-
ing and irrigation scheduling. Soil types vary but the
primary type is clay loam. Liquid loading rates average
1.2 in./wk.
There are no provisions for storage of excess effluent.
Consequently, a significant amount of water in excess of
irrigation requirements must be applied to the land during
the winter months. This excess is normally applied to pas-
ture land which is least affected by excessive irrigation.
Water not consumed by the crop is lost to deep seepage and
runoff to low-lying areas south of the site. The water
lost to runoff floods these low lands and stands until it
is ultimately lost to deep seepage and evaporation.
Conversely, the summer irrigation requirements are in ex-
cess of the sewage flow, and groundwater must be pumped to
make up the difference.
217
-------
Mount Vernon Sanitary District, California
Effluent from the Mount Vernon trickling filter plant
(3.6 mgd) is discharged onto approximately 1,000 acres of
irrigated land adjacent to the City of Bakersfield irriga-
tion site. During fiscal year 1970-1971, however, only
650 acres were cultivated. The crops grown on the Mount
Vernon farm during 1970-1971 include alfalfa, pasture, and
barley. These crops are flood irrigated at a loading of
1.4 in./wk. The clay loam soil, when irrigation began in
1948, was alkaline in nature. The alkaline condition has
been amended by leaching with excess irrigation water and
the addition of gypsum. Originally, the land cost $65 per
acre and its present value is about $1,000 per acre. As at
the Bakersfield farm, excess effluent is applied to pasture
land during winter months with runoff collecting on low-
lying areas to the south. This imbalance is magnified at
times because the Mount Vernon plant does not have suffi-
cient equalizing reservoir capacity that would allow con-
stant application rates of irrigation water.
Campbell Soup Company, Chestertown, Maryland
The Chestertown plant is also a poultry processing operation
that does not include killing and eviscerating. Production
began early in 1960. A new concept of wastewater irriga-
tion, one known as the "bubbling orifice" principle, was
attempted. In this concept, the raw wastewater, after
screening, is distributed to the irrigation fields by a net-
work of underground gravity-flow pipes. At regularly spaced
'intervals, 1-inch riser pipes extend up from the distribu-
tion pipe to just above the ground surface. Little or no
attempt was made to change the contour of the existing land.
As the wastewater "bubbled11 out onto the ground, it followed
the normal contours of the land, and eventually the major
volume of water percolated into the soil.
The bubbling orifice system was found to have several seri-
ous shortcomings. Since all of the flow was by gravity,
the distribution of wastewater onto the land was poor.
Also, because of gravity flow, solids and grease had a tend-
ency to settle out and coat the piping distribution system,
sometimes to the point where lines would become entirely
blocked. Finally, poor land utilization resulted in severe
limitations to the treatment capacity. Because of the poor
efficiency of the bubbling orifice system, the plant em-
barked on a program of replacing the bubbler system with a
high pressure spray irrigation system.
The soils at Chestertown are unique in that some are sandy
while others contain a high percentage of clay. Therefore,
218
-------
a combination of both infiltration-percolation and overland
flow systems was created. Roughly 80 acres of clay soil
were graded and reshaped to form a series of slopes and
runoff terraces, discharging into a receiving stream. An
additional 20 acres of sandy soil was utilized for
infiltration-percolation. To improve the infiltration ca-
pacity of these sandy soils, perforated drainage pipe was
installed at a 5-foot depth with its discharge routed to
the receiving stream.
The wastewater pretreatment operation consists of screening
and gravity grease removal. Sanitary sewage is treated
separately. The high pressure pumps transfer the waste-
water to the spray fields via an asbestos-cement force main,
In the overland flow portion of the fields, the water is
distributed onto the slopes through surface aluminum pipe
and sprinklers. The slopes range from 175 to 250 feet in
width, with sprinklers spaced 80 feet apart along each line,
In the infiltration section of the system, the lateral pip-
ing is underground polyvinylchloride pipe, with sprinklers
spaced on a 100- by 80-foot grid. All of the treated efflu-
ent from both parts of the system, with the exception of
that which escapes into the groundwater, is collected and
chlorinated before being discharged to the stream.
The control system at Chestertown is identical to those at
the other Campbell operations in Paris, Sumter, and
Napoleon. Reed canary grass is also utilized, and the same
microbiological activity exists throughout the system.
The quantity of wastewater discharged to the treatment sys-
tem is approximately 700,000 gpd. Although the total area
involved is approximately 100 acres, only about 70 of these
can be considered wetted acres. This results in an averag-r
rate of about 0.4 in./day.
The treatment efficiency of the Chestertown system averages
more than 99 percent BOD removal. The BOD of the raw and
treated wastewater average 800 mg/L and 5 mg/L, respec-
tively, while the suspended solids average 348 mg/L and
28 mg/L.
Campbell Soup Company, Napoleon, Ohio
The overland flow technique was pioneered at this soup pro-
duction plant in 1954. A 300-acre site adjacent to the
plant was selected to provide treatment for peak wastewater
loads generated by increased processing activity during
tomato season, when the daily average wastewater volume is
nearly doubled and too great in quantity for the conven-
tional trickling filter system, which normally accommodates
219
-------
processing water for 10 months a year. Therefore, all flows
above the design capacity of the conventional system are
routed to the overland flow system.
The soils of Napoleon are silt and clay and were originally
deposited during the ablation period of the Wisconsin gla-
cier when Lake Maumee covered a vast area in northwestern
Ohio. Therefore, with the exception of a sandy ridge across
the property (which was formerly a beach), the soils are
characterized by low infiltration and low permeability.
This established a severe limitation on the quantity of
water that would infiltrate into the soil as normally occurs
in conventional spray irrigation systems. In an effort to
overcome this, the natural terrain of the land was utilized,
and irrigation pipe was located near the top of individual
slopes. This pipe distributed the water along the crest of
the slopes from whence it flowed downhill slowly over the
soil surface and became purified enroute. Little emphasis
was placed on the quantity of water that actually infil-
trated into the soil mantle.
It was found that, if operated correctly, this system of
"overland flow" achieved excellent wastewater treatment
efficiency. Although the original installation was success-
ful, it was soon evident that better land use efficiency
would have greatly reduced the installation cost.
Nevertheless, it provided an excellent background for the
establishment of other systems, particularly those in Paris,
Texas, and Chestertown, Maryland. Experience with these
systems led to even further design refinements, and the
Napoleon installation is presently undergoing a program of
redevelopment. Utilizing the information gained from opera-
tions in Paris, the original slopes are being regraded for
better land utilization and greater treatment capacity.
The Napoleon plant processes canned food consisting chiefly
of vegetables". The pretreatment facilities consist of
screening and gravity grease separation. The high pressure
pumping system discharges into an underground force main
which delivers the wastewater to the spray fields. The
newly developed slopes range in width from 175 to 200 feet,
with polyvinylchloride pipe buried along the top of each.
Sprinklers are spaced at 80-foot intervals along each lat-
eral pipeline. In the older areas where the land has not
been regraded, the slope lengths vary widely, and portable
aluminum pipe is connected to the force main system and
laid along the surface of the ground. There are close to
700 sprinklers in the total system. The automatic control
system is similar to that of the other company systems and
will be described in the Paris, Texas, section.
220
-------
As mentioned previously, the main purpose of the Napoleon
spray irrigation system is to protect its conventional
wastewater treatment system from overloads, particularly
during tomato season. Therefore, the spray system receives
its heaviest use during the late summer months. It is also
used to a limited extent in the spring and early summer,
but not during the winter months, although it could be used
in winter if that became necessary.
The grass on the fields is primarily Reed canary and Alta
fescue. It is harvested at least once a year and utilized
in the growing of mushrooms.
During the late summer months, approximately 4 mgd of waste-
water flows to the spray irrigation system. About 250 wetted
acres are presently being used, resulting in an application
rate of 0.6 in./day. The land use efficiency is about
75 percent, i.e., 335 field acres. The average BOD and sus-
pended solids of the applied wastewater are 400 mg/L and
358 mg/L, respectively. The BOD of the treated effluent
averages 19 mg/L, while the suspended solids average
28 mg/L.
Campbell Soup Company, Paris, Texas
The wastewater treatment system at Campbell's plant in
Paris, Texas, was designed to treat all of the wastewater
generated by the food processing operation. The Paris
facility is also a soup plant. The only wastewater not
treated by the company's spray irrigation system is the
sanitary sewage. This rather small portion of the total
water usage is directed to a municipal wastewater treatment
system operated by the City of Paris.
The development of the Paris plant overland flow system
was complicated by several factors. The land available for
spray irrigation had been a victim of extremely poor farm-
ing and soil conservation practices during the cotton boom
of the early 1900s, which resulted in severe soil erosion
over most of the acreage. Around 1940 the land was aban-
doned until purchased by the company in 1960. By this time,
most of the topsoil had disappeared and deep erosion gullies
scarred the land.
The local soils are red clay overlaid by a gray clay loam.
The infiltration capacity is very low about 0.10 in./day--
which precludes the use of the standard infiltration-type
of spray application. Based on the early experience gained
at Napoleon, Ohio, a plan was advanced for the development
of an overland flow spray system. Unlike the Napoleon sys-
tem, where gently rolling topography made it relatively
221
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easy to construct an overland flow system, the devastated
land at Paris necessitated a complete overhaul. Using heavy
earthmoving equipment, approximately 500 acres of land were
transformed into a network of slopes and terraces. The en-
tire area was seeded, fertilized, and irrigated with fresh
water, to establish a good growth of sod prior to the appli-
cation of wastewater.
Before being discharged into the spray irrigation system,
the food processing wastewater is routed through a gravity
grease separator complete with mechanical grease skimming
and bottom sludge removal, and then through a series of
rotary drum screens. The screened water is then pumped into
the spray system by high pressure pumps. An asbestos cement
force main system distributes the wastewater to 123 auto-
matic valves located on each of the individual slopes, from
whence it is applied to land via aluminum surface piping
and sprinklers. After 10 years of experience the worn
aluminum piping is being slowly replaced by buried poly-
vinylchloride piping. There are more than 700 sprinklers
in the system with discharge varying between 14 and 30 gpm.
Most of the sprinklers are spaced 80 feet apart on each
line, while the individual slopes are all some\diere between
200 and 300 feet wide. The pitch of the slopes varies be-
tween 1 and 12 percent, and this was more or less dictated
by the existing topography and the balance of cuts and fills
in the earthmoving operation. The slopes vary in length
from 350 to 1,300 feet.
The entire system is automatically controlled, utilizing
pneumatic valves in the field. The pumping system is con-
trolled by a standard liquid level control system located
in the pump reservoir. These controls are electrically
connected to four modified golf course type clock timers.
When the level control system activates an individual pump,
the pump starting circuit energizes a clock timer. The
timer is connected to the individual field valves by a net-
work of underground polyethylene tubing which supplies com-
pressed air to close the valves. A plug board used for
grouping and regrouping the various sprinkler lines is in-
tegrated with the clock timers. Activation of the clock
timers by the pumping system results in the opening of a
set of valves which had been prescheduled by the plug board
arrangement. The timer keeps that particular set of valves
open for a predetermined period of time and then automati-
cally closes that set and opens another, and so on.
After the wastewater is distributed along the top of the
slope, it trickles downward across each slope to the ter-
races at the bottom. These terraces run together to form
larger waterways, and eventually all the waterways flow
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into a small stream which runs through and away from the
plant property. The wastewater is purified in this process
by several means. The major treatment mechanism is the bio-
logical activity of the microorganisms present on the soil
and in the vegetative growth. These organisms convert the
organic compounds contained in the waste back into the harm-
less basic elements. The grass also captures the nutrients
contained in the water and utilizes them for growth.
Once a set of sprinkler lines is activated, it is programmed
to run for 6 to 8 hours continuously. A rest period of at
least twice the length of the operating cycle is also pro-
grammed into the controller. Grass cutting and harvesting
cause alterations to this schedule, but only about twice a
year.
Since the Paris system is built on clay soil, little infil-
tration occurs. In fact, only about 20 percent of the
applied volume of wastewater finds its way into the soil,
while an additional 20 percent is lost through evapotrans-
piration, and the remaining 60 percent flows into the water-
ways and away from the property.
The treatment facility was originally expected to be capable
of treating approximately 3.5 mgd. Although the 500 acres
of irrigation land were reshaped specifically for treatment
purposes, experience has shown that land utilization at
Paris is only fair. For example, effective treatment can
be achieved with slopes of only 175 feet in width rather
than the 200- to 300-foot slopes. Also, the optimum pitch
of the individual slopes has been found to be 2 and
6 percent. The original design of the spray system assumed
application rates of 0.25 in./day and 0.50 in./day in winter
and summer, respectively. This was based on an estimated
wetted area coverage of about 75 percent. The actual appli-
cation, however, resulted in a wetted area coverage of less
than anticipated and, therefore, an application rate aver-
aging approximately 0.60 in./day.
The treatment efficiency of the system has continuously
been extremely high, as witnessed by the data in Table 31.
For example, the BOD removal averages greater than 98
percent. One other aspect of the system that merits com-
ment, and that can also be seen in the same table, is the
tremendous buffering capacity of the system. Although the
quality of the applied wastewater varies quite widely
(notice the range of pH and conductivity) during a typical
24-hour period, the quality of treated effluent remains
quite constant.
223
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Table 31. Wastewater Characteristics of Plant
at Paris, Texas
Characteristic Raw v:astewater Treated effluent
BOD, mg/L 490 8
Suspended solids, mg/L 245 24
Total solids, mg/L 500 262
COD, mg/L 740 33
pH, range 5.1-9.3 6.2-8.0
Conductivity,
micromhos, range 330-800 400-530
A byproduct of the system is the grass which is grown
on the fields. Reed canary grass has been found to be
especially well suited to the spray application, and has
yielded large quantities of high quality hay. Based on
actual nutritional analyses, this hay is equal to most
high quality alfalfa, and when sold as a cash crop, returns
at least 5 percent of the operating cost of the system.
Production increases during the past few years have gener-
ated larger quantities of wastewater to be treated. Present
volumes exceed 4 mgd at times. Therefore, an additional
140 acres of land were added to the original system and were
put into use during January 1973.
Hunt-Wesson Foods, Inc., Davis, California
This tomato canning plant produces up to 4 mgd of waste -
water which is treated by overland flow. Screened waste-
water is pumped to the field and sprayed onto 2.5 percent
slopes. Total site area is 320 acres although approximately
250 are field acres. The system was put into operation in
1971.
A series of 28 benches were built in a sawtooth manner.
Each bench is 175 feet wide and 2,400 feet long. In addi-
tion to commercial fertilizer, gypsum was added to the clay
soil at 12 tons/acre to promote grass growth. The field
was planted to a mixture of Reed canary, fescue, trefoil,
224
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and Italian rye grasses. Reed canary grass has emerged but
has not become the dominant species after 2 years of
operation.
The sprinkler system has buried laterals. Sprinklers are
spaced every 100 feet along the 2,400-foot bench, and they
are 65 feet from the top of the 175-foot slope. Individual
sprinklers discharge 25 gpm at 60 psi for an effective
diameter of 130 feet.
Capital costs in 1970-1971 were about $1 million, and oper-
ating costs range from $20,000 to $40,000 depending on the
hay crop. The first cutting in 1971 yielded 1 ton/acre,
while the cutting in 1972 yielded 1.5 ton/acre.
Runoff water is collected in a concrete pond for monitoring
prior to discharge to the adjacent drainage channel.
Monitoring is for pH in the wastewater and dissolved oxygen
in the channel.
California Gartners 5 Growers , Thornton, California
This cannery in northern San Joaquin County processes toma-
toes and produces 2.5 to 3.0 mgd of wastewater. Operation
generally runs from mid-July to October. Wastewater is
applied to the land by spraying on about 60 acres and by
flooding on about 65 acres.
The average loading rate is 0.7 in./day on a very fine sandy
loam soil. This rate is excessive, and by late September
approximately 40 percent of the applied water appears as
runoff. This water is collected in a common sump and dis-
charged to the Mokelumne River.
Approximately 20 acres of ponds are available for pretreat-
ment; however, only one pond was used in 1972 as a settling
basin prior to the wastewater pumping station. The waste-
water is pumped to the spray field for 30 minutes on each
of 8 sprinkler settings. The wastewater then goes to the
flood field for 4 hours, where it is distributed by gated
pipe.
As a consequence of the heavy liquid loading, mosquito and
psychodid propagation has occurred. The frequent applica-
tions maintain an excellent habitat for these insects in
the nut grass. In response to these problems and some odor
complaints, the company is purchasing additional land for
flood irrigation.
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Campbell Soup Company, Sumter, South Carolina
Campbell's plant at Sumter, South Carolina, is a large
poultry processing facility which went into operation dur-
ing 1965. A spray irrigation system was designed to treat
the entire plant wastewater on a year-round basis. Sani-
tary sewage is treated separately.
The land available was nearly flat, and the soils contained
a high percentage of medium sand with extremely high infil-
tration capacity--on the order of 10 in./hr surface
infiltration. Although this situation seemed to lend it-
self perfectly to the conventional infiltration type of
spray irrigation, the sandy clay understructure seriously
limited the downward percolation of water.
To overcome this barrier, which was located about 6 feet
below the surface, perforated drainage pipe was installed
in a network which covered approximately 150 acres of land
at a depth of 5 feet. _ This allowed full use of the high
infiltration sand layer above the drainage pipes and pro-
vided a route of escape for the purified water that could
not penetrate the sandy clay subsoil.
Scattered throughout the Sumter region are shallow depres-
sions in the soil which are believed to have been caused by
a meteor shower. These depressions, which are known as
"Carolina Bays," are usually 6 to 8 feet deep and range in
size from 1 to 100 acres. A 57-acre "bay," which had been
artificially drained, lay in the path of the natural drain-
age from the treatment area, and since there was no way to
avoid it, the company decided to dam the outlet and convert
the bay into a lake. After a couple years of ecological
adjustment, the lake has now become a beautiful wildlife
preserve, which is literally teeming with fish, reptiles,
and water fowl in perfect ecological balance.
Because of the nature of the processing operation, a large
amount of solids and grease are generated. Feathers and
offal are collected in separate screening systems, each con
sisting of rotary drum screens. Grease is separated from
the wastewater in a vacuum flotation system. All solids
collected in the pretreatment system are sold to a render-
ing operation.
The wastewater is distributed to the spray irrigation sys-
tem by high pressure pumps and a control system with clock
timers and pneumatic valves similar to the arrangement at
Paris, Texas. All of the pipe in the Sumter system is
buried. The force main from the pumps to the individual
valves is asbestos-cement pipe, while the smaller lateral
226
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lines are polyvinylchloride. There are over 600 sprinklers
in the system which discharge between 20 and 30 gpm each.
The field system consists of two separate areas. The older
original network is approximately 100 acres, while the newer
section is roughly 50 acres. The piping layout in the first
section is such that the sprinklers are located on a
120-foot triangular spacing pattern. Experience has shown
that better land utilization could have been achieved with
no lessening of treatment efficiency by reducing this
spacing. Therefore, the newer 50-acre portion of the field,
which went into full-scale operation in 1971, utilizes a
grid pattern of 80 by 100 feet for sprinkler spacing.
Since the spray irrigation principle at Sumter is infiltra-
tion, only minor changes to the existing topography were
needed. As the wastewater is applied to the land it soaks
directly into the soil. Part of the water percolates
through the sand-clay strata and into the groundwater re-
serve; the remainder is picked up by the perforated drainage
pipe. Reed canary grass is the dominant species in the
Sumter system. The operational schedule consists of 6 hours
of continuous spraying on any particular cycle and 12 or
more hours of rest.
The Sumter system treats an average of 3.5 to 4.0 mgd of
wastewater. Spread over 150 acres, this amounts to an ap-
plication rate of approximately 0.9 in./day. Treatment
efficiency is excellent, with BOD reduction averaging above
99 percent. The raw and treated wastewater characteristics
were given in Table 23 in Section VI.
Seabrook Farms Company, Seabrook, New Jersey
The spray irrigation system of Seabrook Farms Company has
been in continuous operation since June 1950 , receiving an
annual application of 1.25 billion gallons of wastewater
distributed over an area of 310 gross acres. The waste-
water, which originates from processing of vegetables,
ranges in BOD from about 200 mg/L to around 2,000 mg/L de-
pending upon the product being processed. (All sanitary
waste is treated separately, and the treated water is not
mixed with industrial waste stream.) The quantity of water
is also highly variable, ranging from a few hundred thousand
gallons per day in winter to 16.0 mgd at the height of the
packing season.
The problem of stream pollution was recognized during the
late 1930s, but because of the wartime shortage of construc-
tion materials, little pollution control was attempted--
save the construction of some lagoons which by 1946 were
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totally inadequate. During the next 2 years engineering
studies led to no feasible means of pollution control that
was within the company's financial capability. Finally,
the company asked Dr. C. Warren Thornthwaite to investigate
the possibility of disposal by irrigation.
Effluent of the quality produced by Seabrook Farms is en-
tirely suitable for crop irrigation and indeed had been
used for this purpose for many years. However, crop de-
mands for water do not coincide seasonally with the harvest
schedule. In fact, during the asparagus season in spring
and again during spinach harvest in the fall, excess mois-
ture from rainfall is always a threat and often a problem.
Therefore, Thornthwaite's first task was to locate fields
within piping distance of the factory which would be in
cover crop during high rainfall periods and to discover by
trial just how much water these fields could be expected to
absorb. It is, perhaps, fortunate that the irrigation ex-
periments at Pennsylvania State University were to come 15
years later. That is, if Thornthwaite had been constrained
by the concept of 2 in./wk, he would have abandoned the
project before it got started, since the 1,800 acres needed
to handle 14.0 mgd were simply unavailable.
During periods of drought in the humid East, farmers nor-
mally apply 1 inch of irrigation water about once a week.
Therefore, it was necessary to learn how much more water
the land would accept. To achieve this, Thornthwaite set
up a single giant sprinkler in a sandy field with a vigor-
ously growing cover crop of crimson clover. The results
were disappointing. After the application of 2 inches, the
soil was waterlogged and became waterlogged again with the
application of only a fraction of an inch on successive
days. Clearly, something was impeding the movement of
water through the soil--probably plow sole which had been
formed during 100 years of tillage.
Thornthwaite then moved the sprinkler 200 yards northward
into a wooded area which had not been farmed for many years
and was astonished when the area did not flood after 8 in-
ches of application. The application was repeated daily
for several days with the same result. Finally, after 48
hours of continuous irrigation at the rate of 1 in./hr,
ponding "occurred, but the ponds disappeared after a few
hours' resting.
During the winter and spring of 1950, the Seabrook system
was constructed to occupy wooded areas adjacent to the ex-
perimental tract. Initially, there were 72 sprinkler
locations --each designed to receive 8 in./day. Each sprink-
ler covered a little over an acre, and water was applied at
228
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approximately 300 gpm. Later 12 more sprinkler locations
were added when some areas did not perform as well as
expected.
At the outset 76 test wells were installed and monitored
for groundwater pollution. It soon became evident that the
water quality was well within the United States Public
Health Standards. Nitrate, for example, was never higher
than 10 mg/L (2.2 as N). The monitoring program was discon-
tinued after about 3 years. The test wells also enable in-
vestigators to plot the movement of groundwater and led to
the publication of several papers oh groundwater hydrology.
For at least 8 years and probably longer, the original de-
sign concepts were followed, i.e., 8 in./day during periods
of stress and lesser quantities when factory production
diminished. Meanwhile, a rigorous water economy program
reduced the peak flow from 14.0 mgd to about 12.0 mgd.
The soils of the Seabrook treatment site lie within the
Sassafras soil formation and are generally sandy in
character. However, within the spray area, the silt and
clay content is extremely low, resulting in a very low
water retention capacity. Therefore, the land has low
agricultural value and for this reason was abandoned to
forest many years ago.
In 1950 the trees were largely oaks with a few cedars, iron-
wood, gum, and dogwood scattered amongst them. The growth
was sparse and scrawny with large trees only in the low
areas where water was available. Clearly this vegetation
was thoroughly acclimated to the poor soil and was able to
survive long periods of severe drought. It just barely
missed becoming a grassland area similar to the Quinipiac
Valley in Connecticut where glacial outwash deposited sev-
eral feet of sterile sand. It was obvious from the outset
that these deep rooted upland oaks could not survive the
application of large quantities of water which drowned the
zone of aeration. Surprisingly, however, the trees have
survived in areas immediately adjacent to the sprinkler
circle, indicating very little lateral movement of water
near the soil surface.
Nothing has ever been done at Seabrook to alter the natural
ecological succession, and observations over the years in-
dicate that the flora and fauna have now stabilized in their
new environment. During the first few years while the trees
were dying, a weed known as Lambs Quarters grew to gigantic
proportions. Gradually, this growth was replaced by smart
weed, chick weed, blackberries, wild currant, and wild
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roses. The dominant species now is marsh grass of a vari-
ety that grows to a height of 10 feet or more in the low
lands of New Jersey--very decidedly a foreigner to these
upland soils of the spray area. It is also noted that the
vegetative litter on the soil surface has ceased to accumu-
late, indicating that the rate of production is now matched
by the rate of degradation.
The water for the Seabrook factory is pumped from 14 deep
(150-foot) wells, all located within an area of less than
one-half section. After being.discharged from the factory,
the water flows by gravity to a screening station where
small pieces of vegetables are removed on vibrating screens,
From there the water flows to a lift station and thence
into a canal which conveys it 1.7 miles to the disposal
site. The capacity ,of the canal is 3.0 million gallons and
provides the treatment system with adequate surge capacity.
Located along the canal are two major pumping stations
which remove water during the summer for the irrigation of
vegetable crops. (Since there is zero input of pathogens
or residue of an animal nature, there is no constraint upon
the use .of this water for this purpose.) Downstream from
the field irrigation pumping stations are seven 100-hp .
pumps which supply the treatment area. These discharge
into 8-inch steel force mains which, in turn, break down to
4-inch laterals to supply each nozzle.
Hydrological studies during the early 1950s showed that the
water applied to the treatment area flowed underground in a
general southwesterly direction. It probably emerges as
springs and seeps in the watershed of the Cohansey River.
Because of this southwesterly flow, it is highly unlikely
that any of the treated water finds its way northeasterly
to the well field that supplies the factory. Therefore,
the only reuse that can be claimed is the relatively small
quantity withdrawn from the canal for crop irrigation.
In the early 1950s there was a complete shutdown of the fac-
tory during winter and the treatment area received no water,
Around 1953 the winter processing of potatoes made it neces-
sary to operate the system during weather that occasionally
dropped to below zero. At first there was apprehension
that the surface piping could not survive under these ex-
treme conditions and that wastewater would flow into the
streams over the frozen sqil if there was a sudden thaw.
The problem was solved by disconnecting all but three
sprinklers on each operating line and operating these con-
tinuously as long as the weather remained cold. This tech-
nique caused the formation of huge blocks of ice within the
sprinkler pattern. When warm weather returned the ice
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melted slowly from the bottom up and gradually percolated
into the soil. No overland runoff has been experienced.
Aside from the continuing high performance which many pre-
dicted would be exhausted by now, the most significant
change in the system has been an alteration of the soil
structure. One can only speculate as to what has happened,
but it is very evident that the soil has become even more
permeable than it was in 1950.
As mentioned previously, standard operation initially called
for the application of 8 in./day at the rate of 1.0 in./hr
during peak flow periods. Careful scheduling was maintained
during periods of less than peak flow so that each area was
given opportunity to rest and recover to be ready to accept
the next increment of heavy flow. In 1973 the operating
time has been extended to 12 hr/day, and even more impor-
tant, there is no attempt to distribute the flow evenly
throughout the tract. That is, when production falls off
the areas most distant from the control house are not used,
and the nearby sprinklers continue to receive the 12 inches
per application. Thus, in theory, a single sprinkler might
receive as much as 350 acre-ft/yr which closely approaches
the loading rate of percolation beds at Flushing Meadows,
Arizona. Quite obviously this change in operation has
brought about a substantial saving in labor.
The piping and sprinkler arrangement has not been signifi-
cantly altered in 20 years, and there has been no attempt
to automate the controls. In fact, the labor cost of oper-
ation is so low that automatic controls would only be a
convenience and could not be justified by a savings in
labor.
The annual operating cost is on the order of $60,000 which
reduces to 4.8^/1,000 gal. It should be pointed out, how-
ever, that because of the seasonal nature of the Seabrook
operation, the flow from the factory on a year-round basis
is only 30 percent of the designed capacity of the treat-
ment system. That is, if the flow were a uniform 10 or
12 mgd', the cost of treatment would be significantly less.
Three or four years ago a rumor was being circulated among
local residents that Seabrook was responsible for the eutro-
phication of a downstream lake. And there was suspicion
that the phosphorus adsorption capacity of the Seabrook
treatment system had been finally exhausted. Accordingly,
10 new test wells were installed and samples were collected.
Although the specific results of sample analysis are not
available, the company has let it be known that the phos-
phorus removal is nearly complete, and that there has been
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no change in the groundwater quality since the sampling pro-
gram of 20 years ago.
The waste treatment system of Seabrook Farms Company, after
23 years of operation, continues to achieve a very high
degree of water purification. Quite contrary to early pre-
dictions the system has lost none of its treatment effi-
ciency and has, in fact, improved. The original vegetation
within the sprinkler pattern has been replaced by species
that are ideally adapted to the environment. The Seabrook
system has become an outstanding example of perfection in
ecological succession.
Sevastopol, C_aJ_iforn_ia.
Industrial wastewater from five relatively small canneries
processing apples and cherries is applied to the land by
spray irrigation. The average flow is 0.3 mgd.
The soil in the 54-acre site is a clay loam. The applica-
tion rate is 1.2 in./day, with 7 days of resting or an
average loading rate of about 1.2 in./wk. Pretreatment
consists of screening through a 10-mesh rotary drum screen.
Sprinklers are spaced in a rectangular 50- by 60-foot grid.
The 3/16-inch nozzles with nylon openings discharge 7.8 gpm
at 60 psi. Laterals are 2-inch polyvinylchloride.
The wastewater characteristics are BOD, 1,800 to 3,000 mg/L;
suspended solids, 75 to 160 mg/L; and pH 4 to 6.
The operation began in July 1972 without the drum screen in
place. The screen had a capital cost of $6,500. The 54
acres cost $44,150 with site preparation of $2,700. Trans-
mission for 15,000 feet with a crossing of Laguna de Santa
Rosa cost $46,900, and distribution cost $32,000. Operation
cost is estimated at $3,400 per year.
Tri/Valley Growers, Stockton, California
The Tri/Valley plant north of Stockton is a cannery that
processes tomatoes, asparagus, carrots, and brine cherries
on a seasonal basis. Approximately 3 mgd of wastewater is
spray irrigated on 90 acres of heavy clay loam. The load-
ing rate of 1.2 in./day is excessive, and a mosquito propa-
gation problem, similar to the one at California Canners §
Growers, has occurred.
The sprinkler systems consist of portable aluminum, 16-inch
diameter mains and 4-inch diameter laterals. Screening of
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the wastewater is done within the plant, and the pump dis-
charge lines are equipped with in-line screens. The waste -
water is applied successively to each of nine 10-acre
sections for 3 hours at a time. As indicated, the applica-
tion is excessive and ponding occurs. Runoff flows back to
the holding pond. It is repumped into the pond and even-
tually resprayed onto the fields.
As with California Canners § Growers, Tri/Valley intends to
expand its system for 1973. An additional 75 acres has
been purchased for expansion.
SITES VISITED BY APWA
The American Public Works Association in 1972 conducted a
field survey of 100 facilities using land application of
municipal and industrial wastewaters. Interviews could not
be held at some facilities; however, there were 82 facili-
ties to which on-site visits were made, and the data were
presented in APWA's "Survey of Facilities Using Land
Application of Wastewater,11 published by the EPA in 1973.
The 82 sites are listed in Table 32. Ten other sites were
visited, but the data were not included in APWA's report.
These 10 sites are listed in Table 33.
Additional data were gathered by APWA for many existing
facilities by means of a mail survey. In response to this
survey 78 cities and 36 industries, listed in Table 34,
provided data to APWA.
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Table 32. Land Application Facilities
On-Site Visits by APWA
No.
Agency and State
No.
Agency and State
A. MUNICIPAL
ARIZONA
1
2
3
4
5
6
7
8
9
10
11
12
13
City of Casa Grande
Lake Havasu San.
District, Lake Havasu
City of Mesa
City of Prescott
City of Tucson
CALIFORNIA
Las Virgenes
Municipal V.'ater
District, Los
Angeles
Camarillo San.
District, Camnrillo
City of Colton
City of Dinuba
City of Font an a
City of Fresno
City of Hanford
Volley Sanitation
17
18
19
20
21
22
23
24
25
26
27
28
29
Irvine Ranch Water
Dist . , Irvine
City of Oceans ide
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
COLORADO
City of Colorado Springs
FLORIDA
Walt Disney World
Oskaloosa County Water
and Seiver District
District
14 Ronsraoor Sanitation,
Inc. jl.aguna Hills
15 City of Livcriiiore
16 City of Lodi
Eglin Air Force Rase
30 City of St.Petersburg
31 City of Tallahassee
MARYLAND
32 St. Charles Utilities,
Inc., St. diaries
234
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Table 32. (Continued)
No. Agency and State
No. Agency and State
NEW JPRSP.Y
33 Tors gale Sanitation,
Inc. , Cranbury
34 City of Vineland
NEW NEXT CO
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 Pe
Airport Road Plant
NEVADA
41 Clark County
42 City of Ely
43 Incline Village
44 City of Las Vegas
OKLAHOMA
45 City of Duncan
OREGON
46 Unified Sewerage
Agency, J-nre?t Grove
47 City of Hillsboro
48 City of Milton-Freewater
PENNSYLVANIA
49 Pennsylvania State U.
State College-University
Park
TEXAS
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
WASHINGTON
57 City of Ephrata
58 Town of Quincy
59 City of Walla Walla
WYOMING
60 City of Cheyenne
61 City of Rawlins
MEXICO
62 Mexico City , dry
weather flow, treated
63 Mexico City, dry
weather flow, raw
235
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Table 32. (Concluded)
No. Name, City, and State
No. Name, City, and State
B. INDUSTRIAL
li Green Giant Company
Buhl, Idaho
2i Western Fanners Assoc.
Aberdeen, Idaho
3i Celotex Corporation
Largo, Indiana
4i Commercial Solvents
Terre Haute, Indiana
5i Chesapeake Foods
Cordova, Maryland
6i Celotex Corporation
L'Anse, Michigan
7i Gerber Products Co.
Fremont, Michigan
8i Michigan Milk Producers
Assoc., Ovid, Michigan
9i Simpson Lee Paper Co.
Vi ckshurp.. M> rhj ;*an
lOi Grucn Giant Company
Montgomery, Minnesota
Hi Stokcly Van Camp
Fairmont, Minnesota
12i II.J.Heinz Company
Salen, Ncv.' Jersey
13i Hunt-Wesson Foods, Inc.
Bridgeton, New Jersey
14i U. S. Gypsum Company
Pilot Rock, Oregon
15i Weyerhauser Company
Springfield, Oregon
16i Pet Milk Company
Bigler;rille, Pennsylvania
17i Howes Leather Company
Frank, West Virginia
18i American Stores Dairy
Company, Fairwater,
Wisconsin
19i Libby, McNeill 't, Libby
Janesville, Wisconsin
236
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Table 33. Facilities Visited
by APWA, Data Not Tabulated
No.
1
Name
Barstow, California
Re as on
Irrigate only sewage treatment
2 Madera, California
3 Porterville, California
4 Visalia, California
5. Whittier Narrows,
California
6 Yuba City, California
7 Nantucket , Massachusetts
8 Scituate, Massachusetts
9 Gallup, New Mexico
10 Hobbs, New Mexico
plant grounds
Infiltration-percolation
Infiltration-percolation
Flow discharged to ditch
All flow used by abutting property
owner
Infiltration-pereolation
Infiltration-percolation
Infiltration-percolation
Infiltration-pereolation
Facility abandoned
Facility abandoned
237
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Table 34. Responses to Mail Survey by APWA
No.
Agency and State
No. Agency and State .
2
3
4
5
6
7
9
10
11
12
13
14
15
1C
ARIZONA
City of Wins low,
WW Plant
CALIFORNIA
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 Flsinore
Dept.of Parks f, Rec.
San Diego
Eastern Mun. Water
Dist., San Jacinto
City of Escalon
Falibrock Sanitary
District
City of Greenfield
City of Gridley
A. MUNICIPAL
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
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
District
City of Paso Robles
City of Reedley
City of Ripon
City of Riverbank
City of Riverside
San Bernardino County
Special Districts Div.
San Juan Bautista
City of Santa Paula
City of Santa Rosa
City of Solcdnd
238
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Table 34. (Continued)
No. Agency and State
No. Agency and State
CAI, T FOUNT A
37
38
Strathnore
Util. Dir.t.
Terra
Bella
Pub.
Sever
53 Village of Middleville
54 Ottaw
Road
MHVT A
a County, Co.
Commission
M A
Main. Hist.
39 City of Tipton
40 City of Tulare
41 City of Tuolumne
42 Valley Center Munic.
Water District
43 Waterford Comm.Serv,
District
44 Kcstwood Cornm. Serv.
District
45 Kheatland Dept. of
Public IVorks
46 City of Woodland
KANSAS
47 City of Scott City
48 City of Sublette
MICHIGAN'
49 Village of Cassopolis
50 City of East Jordan
51 Harbor Springs Area,
Sewage Disposal Auth.
52 City of Harrison
55
56
57
58
59
60
61
62
63
64
65
66
City of Helena
City of West Yellowstone
NEBRASKA
City of Grant
NEVADA
City of Winnemucca
NEW MEXICO
City of Lovington
NORTH DAKOTA
City of Dickinson
OKLAHOMA
Boise City
OREGON
City of Bend
TEXAS
City of Cotulla
City of Coleman
City of Comanche
City of Dalhart
239
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Table 34. (Continued)
No. Agency and State
No. Agency and State
TEXAS
67 City of Denver City
68 City of Els a
69 City of Goldthwaite
70 City of Idalou
71 City of Morton
72 City of Munday
73 City of Rails
74 City of San Saba
75 City of Seagraves
76 City of Van Horn
77 City of Winters
WASHINGTON
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
(Princeville-Peoria)
Illinois
4 Joan of Arc Company
(Hoopeston-Vermilion)
Illinois
5 Green Giant Company
Belvidere, Illinois
6 Campbell Soup Company
Saratoga, Indiana
7 Popejoy Poultry
Logansport, Indiana
8 Kcston Paper § Mfg.Co.
Terre Haute, Indiana
9 Albany Cheese, Inc.
Grayson, Kentucky
10 Duffy-Mott Co., Inc.
Hartford, Michigan
11
12
13
14
15
16
17
18
19
20
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 5 Sons,Inc.
Dunn, North Carolina
The Beckman § Cast Co.
Mercer, Ohio
Crown Zellcrbach
Baltimore, Ohio
Deeds Bros.Dairy, Inc.
Lancaster, Ohio
Libby, McNeill § Libby
Liepsic, Ohio
240
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Table 34. (Concluded)
No. Name, City, and State
No. Name, City, and State
21 Sharp Canning, Inc.
Rock ford, Ohio
22 Campbell Soup Co.
Paris, Texas
23 Tooele Ci ty Corp.
Tooelc, Utah
24 Lamb-Weston
Div. of Amfac
Connell, Washington
25 Alto Coop Creamery
Astico, Wisconsin
26 Cohb Canning Co.
Cobb , Wisconsin
27 Frigo Cheese Corp.
Wyocena, Wisconsin
28 Green Giant Co.
Fox Lake, Wisconsin
29 Green Giant Co.
Ripon, Wisconsin
30 Green Giant Co.
Rosendale, Wisconsin
31 Hoffman Corners
Coop Creamery
Kendall, Wisconsin
32 Kansas City Star Co.
Park Falls, Wisconsin
33 Kimberley Clark
Niagara, Wisconsin
34 Loyal Canning Co.
Loyal, Wisconsin
35 Mammoth Spring Canning
Oak field, Wisconsin
36 Oconomowoc Canning Co.
Sun Prairie, Wisconsin
241
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APPENDIX B
HISTORICAL CASES OF IRRIGATION ABANDONMENT
To assess the state-of-the-art of land application, an
analysis of reasons for abandonment of systems may add some
insights. As irrigation has been practiced throughout the
country for nearly 100 years, irrigation abandonment was
chosen as a subject for selective inquiries.
INQUIRY DESIGN
On the basis of a 1934 survey by Hutchins [47] which he
updated in 1937, a list was compiled of 121 cities in 15
western states that use irrigation. The list included 68
cities in California and Texas where wastewater used for
irrigation was taken directly from outfalls or treatment
plants, or where effluent was discharged to a stream chan-
nel and later diverted for irrigation. This list of 68
cities was compared to the 1972 Municipal Wastewater
Treatment Plant Inventory compiled by EPA, and a list of
24 cities that had apparently ceased irrigating was
compiled. This list formed the basis for inquiries as to
the time, conditions, and reasons involved in irrigation
abandonment.
INQUIRY RESULTS
Results of inquiries are given in narrative form for the
cities which had actually ended the practice of wastewater
irrigation. Of the total of 24 checked, it was found that
2 in California, Pomona and Susanville, and 2 in Texas,
Canyon and Plainview, were actually continuing their
operations.
California Sites
In general the 13 systems in California were abandoned be-
cause of the tremendous population growth over the inter-
vening 35 years. Treatment plants became overloaded and
had to be expanded and, in many instances, also relocated.
242
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Agricultural lands near the cities were absorbed into the
growing suburbs. In 1949 the State Public Health Depart-
ment [99] promulgated regulations abolishing the practice
of irrigation with untreated sewage and defining the qual-
ity of effluent acceptable for irrigation of various types
of crops. This action led to upgraded pretreatment in most
cases but abandonment of irrigation in others.
Cloverdale, California A sewage farm was being operated
at Cloverdale in 1933 with 2.5 acres of pears, 3.5 acres
of vineyards, and 1.5 acres of fodder corn under irrigation.
In 1949, because of the odors produced and the fact that
untreated sewage irrigation was then declared illegal, the
farm was abandoned. A residential area has since been
developed on the site and a new treatment plant has been
built.
Hemet, California Crops grown at Hemet in 1933 included
100 acres of alfalfa, 30 acres of beet seed, and 10 acres
of hay. Other crops irrigated over the years included milo,
safflower, grain, and apricots, but the largest acreage was
usually planted to alfalfa. Crops were irrigated by spray-
ing and flooding with secondary effluent.
In 1966 the 0.6-mgd activated sludge plant, loaded at a
rate of 0.85 mgd, was abandoned. The sewage from Hemet was
discharged to the Eastern Municipal Water District for
treatment. The effluent from the District is being re-
charged to groundwater, in part, and it is also being sold
to farmers for irrigation water. At the time the plant was
abandoned, 70 acres of City-owned land and 120 acres owned
by an adjacent farmer were being irrigated successfully.
Kingsburg, California - Although not listed as a sewage
farm in 1933, Hutchins reported (1937) that the wastewater
at Kingsburg was being used to irrigate a vineyard. Appar-
ently becauuse of the lye peeling wastewater discharged by
Del Monte, the wastewater was deemed toxic as an irrigation
water and the practice ceased. Presently, 0.5 mgd is being
percolated on 110 acres of sandy soil. With the addition
of the canning wastewater during the summer, the flow rates
range from 2.2 mgd to 2.8 mgd.
Marysville, California Until 1949, the sewage treatment
at Marysville consisted of spreading untreated sewage on
river bottom land. The silt-gravel percolation beds would
be scarified every 3 to 4 days to keep the land from
clogging. In 1933, 25 acres of dry beans were raised on
the sewage farm. In 1949 the State Public Health Permit
243
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System required at least primary treatment for all dis-
charges into the Feather River and, in the case of
Marysville, it prohibited direct discharge to the Feather
River. The sewage treatment plant built in 1949 consisted
of primary sedimentation followed by discharge to percola-
tion ponds. Because the percolation ponds suffered from
undue plugging, secondary treatment was installed in 1963.
There are presently 40 acres of percolation ponds receiving
a flow of approximately 1.7 mgd for an application rate of
11 in./wk.
Modesto, California The history of sewage farming at
Modesto has not been fully documented. Imhoff tanks were
built in 1912, and the effluent was discharged to the
Tuolumne River. In 1933, 78 acres of alfalfa, 60 acres of
vineyards, and 20 acres of hay were being irrigated. In
the mid-1940s this practice was replaced by oxidation ponds
in series. The final pond served as a polishing pond for
discharge to the river.
Two other entities, the Empire Sanitary District and the
Beard Industrial Tract, used the land for wastewater irri-
gation in the 1940s and 1950s. The Beard Industrial Tract
was expanded to nearly 500 acres in 1960. Both of these
dischargers are now handled by the Modesto plant. Cur-
rently, treated effluent is piped 7 miles to some 1,000
acres of ponds on the San Joaquin River.
Orland, California The City of Orland abandoned sewage
irrigation in 1964. The old land disposal site consisted
of 30 acres of pastureland. The reasons for abandonment
were that the land was too close to the center of town and
that the odors generated in the fields were obnoxious. The
loading on the old land disposal site was 0.6 in./day or
4.3 in./wk. The present system consists of 60 acres of
gravel beds for percolation and 60 acres of oxidation and
storage ponds. This land is located 1.5 miles from town
and is receiving an average of 0.5 mgd for an application
rate of 2.1 in./wk. No attempt has been made to raise a
crop on the 60 acres of percolation ponds at this time.
Pasadena, California - Pasadena operated one of the first
sewage irrigation farms in the United States beginning in
1887. Originally, 300 acres were purchased at $125 per
acre and, by 1914, 518 acres were owned. A septic tank was
constructed in 1910, and concrete pipes were laid to dis-
tribute the sewage about the farm. The effluent was not
allowed to run on any area of open ground longer than 4 to
10 days and, as soon as the land was dry, it was thoroughly
cultivated and occasionally plowed. In 1914 the average
244
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application rate was about 1.0 in./wk, and the crops in-
cluded alfalfa, walnuts, "oranges, oats, field corn, pump-
kins, sweet corn, and Kaffir corn. Growth of population
in the farm vicinity led to complaints, and an activated
sludge plant was built in 1924 [81]. In 1933, 75 acres of
oranges, 125 acres of dry beans, and the remaining acre of
grass, were being irrigated successfully.
The post-war urbanization in Los Angeles County forced
changes in land use from agriculture to industry and subur-
ban housing areas. In 1946, because of odor problems at
the Tri-Cities Plant, Pasadena, South Pasadena, Alhambra,
and San Marino joined the Los Angeles County Sanitation
Districts. In 1948 the Tri-Cities Plant was demolished and
the sewage was diverted to a District 16-trunk sewer [98].
Pomona, California Sewage treatment at Pomona in 1930
consisted of an Imhoff tank followed by activated sludge.
The effluent was being sold to the Northside Water Company
for irrigation at $2.50 per acre-foot in winter and $5 per
acre-foot in summer. During 1928-1929 the return from the
sale of effluent was $4,669; the return from the sale of
sludge, $414. The cost of operating the plant was $9,112,
including $1,000 for chlorination [81].
In 1951 Pomona joined the Los Angeles County Sanitation
Districts and the treatment plant was remodeled. Presently,
about 12 percent of the effluent from the plant is pur-
chased from LACSD by the City of Pomona for $7 per acre-foot.
The City resells the effluent to various users for $5 to
$22 per acre-foot. About 500 acres of citrus and forage
crops are being irrigated.
St. Helena, California The sewage treatment works at St.
Helena from the turn of the century until 1967 consisted of
septic tanks followed by discharge to ponds. Sewage irri-
gation was being practiced by nearby orchardists who could
request an intermittent supply of effluent for irrigation.
In 1933, 3 acres of sudan grass, 2 acres of prunes, and a
1-acre nursery were being irrigated. In 1967 the outdated
sewage treatment plant was abandoned and a new site was de-
veloped south of the city. The new plant consisted of pri-
mary sedimentation followed by oxidation ponds with
intermittent discharge to the Napa River. Sewage irrigation
has ceased because of the change in location. No adverse
environmental effects resulted from the sewage irrigation.
Susanville, California - The effluent from the Susanville
sewage treatment plant is discharged to a ditch which runs
approximately one-half mile before it is intercepted by
irrigation ditches that supply wastewater to 5 ranchers.
245
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There has been no abandonment of sewage irrigation during
the summertime. Oxidation pond effluent is being used to
raise hay, to irrigate pasturelands, and to water the stock
The plant flow is 0.8 mgd and between 500 and 600 acres of
land are being irrigated. Currently, the rancher who is
located nearest to the plant is complaining of the odors
prevalent in the ditch which passes his land, and he has
requested that a pipeline replace the ditch. During the
wintertime the flow from the plant is discharged to the
Susan River.
Ukiah, California The effluent from the Ukiah sewage
treatment plant was used to irrigate pear orchards until
1957. In that year, a new plant was built 4 miles from the
original site. The pear growers merely shifted the source
of their supply to the Russian River. In doing this, they
avoided the requirement to halt irrigation within 30 days
before harvesting. Presently, the effluent from the Ukiah
sewage treatment plant is discharged to the Russian River.
Previous crops irrigated at Ukiah included alfalfa and hops
Vacaville, California As reported in 1928 by Gillespie
[39] , septic tank effluent was being irrigated on 8 acres
of grassland. The soil was tight, and 10 percent of the
30 million gallons applied over the summer at the rate of
0.125 mgd accumulated in ponds [81]. The slope Avas about
1.0 percent so that a form of overland flow was actually
being used.
In 1933 the effluent was being used to irrigate an addi-
tional 36 acres of peaches, prunes, pears, and apricots.
Around 1950 the practice was abandoned with the construc-
tion of the Brown Street sewage treatment plant. Today
5 mgd of wastewater receives secondary treatment prior to
discharge to Cache Slough.
Whittier, California The effluent from the Whittier treat-
ment plant was used to irrigate 75 acres of alfalfa in 1933,
A number of farmers and cattle ranchers used the treated
water for pasture irrigation, in addition to alfalfa irri-
gation, and the water came at no expense. When the City of
Whittier joined the Los Angeles County Sanitary Districts
in 1948, Chief Engineer A. M. Rawn negotiated with these
users in an attempt to sell the effluent and offset some of
the costs for increased levels of treatment. The users re-
fused to pay for the water and the sewage treatment plant
was abandoned. The wastewater was incorporated into the
District 18 treatment system [98] .
246
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Texas Sites
In Texas, the population increase has not influenced aban-
donment as heavily as it has in California. Reasons of
nuisance, odors, plant relocation, management changes, and
alternate sources of irrigation water were given for the 9
sites that were abandoned.
Baird, Texas The wastewater from the Imhoff tank at Baird
was used tcT irrigate a small garden area near the treatment
plant until 1967. At that time a new trickling filter
plant was built on the site of the garden. The City owns
no more land in the area and discharges the 0.086 mgd of
treated effluent, after chlorination, into a creek that is
tributary to the Brazos River.
Breckenridge, Texas The trickling filters built in 1922
have been upgraded to treat 0.3 mgd but need further
enlargement. No information was received on when or why
irrigation was abandoned.
Canyon, Texas - Primary effluent was being used for irriga-
tion at Canyon until the 1950s. When a new sewage treatment
plant was built, the old farm was abandoned and is now used
as a city park. A trickling filter plant, followed by
oxidation ponds, was built at a different location. During
the summer months approximately two-thirds of the 1.2-mgd
effluent is sold to a farmer for irrigation of 850 acres.
During the other months of the year the effluent is dis-
charged to a Tierra Blanca tributary stream. There has
been no abandonment of wastewater irrigation although the
original farm has been abandoned.
Childress, Texas Irrigation with Imhoff tank effluent
began at Childress around 1925. The effluent would flow in
an open ditch until it was pumped out for irrigation on
150 acres by a nearby farmer. When the farmer was not
irrigating, the flow in the ditch continued downstream and
served as a source of drinking water for cattle. This
periodic withdrawal led to stagnant ponds in the ditch and
numerous odor complaints. In 1952 the practice of dis-
charging to this dry channel was discontinued because of
the odor complaints. Presently, the trickling filter efflu-
ent, amounting to 0.58 mgd, is discharged to Trosbecks
Creek.
Georgetown, Texas - Irrigation of a pecan orchard near the
city of Georgetown with primary effluent was discontinued
in 1965. Reasons given for the abandonment were odor pro-
duction and mosquito propagation. The loading rate"at the
time of abandonment was 7,000 gad. At present the 0.45 mgd
247
-------
is receiving activated sludge treatment with river
discharge.
Mission, Texas Mission is located in southern Texas about
4 miles from the Rio Grande. An Imhoff tank built in 1926
served as the treatment works with discharge to a floodway
drainage ditch. In 1938 a farmer began pumping the efflu-
ent out of the ditch to irrigate small grain for cattle
feed. After 2 years of operation a flood washed out the
pump intake pool and created a new channel a considerable
distance away. Because the effluent contained 600 to
700 mg/L of TDS, and there seemed to be abundance of irri-
gation water in the Rio Grande valley, the practice of
sewage irrigation was never continued.
Plainview, Texas There has been no abandonment of waste -
water irrigation at Plainview. The practice began in the
early 1930s when Imhoff tank effluent was discharged down a
dry channel. Farmers adjacent to the channel would pump
the effluent and use it for irrigation on a voluntary basis.
When no users pump out the water it travels 6 to 8 miles
before it finally infiltrates into the ground. The prac-
tice has not changed today although the plant now consists
of trickling filters.
Robstown, Texas Presently, Robstown discharges 0.7 mgd of
activated sludge effluent to Ogo Creek. As recently as
1970 a portion of the effluent was used to irrigate turf
grass. No reasons for abandonment were given.
San Marcos, Texas Effluent from the treatment works at
San Marcos has never been used for irrigation. The use
referred to by Hutchins was a temporary application with
liquid sludge for fertilizer. The sludge drying beds were
overloaded, and the excess sludge was applied to the land
until about 1950.
The effluent disposal system for 1.2 mgd from the larger of
the two treatment plants is designed so that the effluent
can be bypassed to irrigate adjacent property. Presently,
the owner of the property feels that the flow is too small
for him to consider converting his irrigation system.
Stamford, Texas Effluent from the treatment works at
Stamford was used to irrigate grain sorghum until 1945.
The City Superintendent of Water and Sewers leased 15 acres
from the City and operated the farm. When he retired in
1945 the practice was abandoned. Presently, an oxidation
ditch is being constructed at Stamford, and the planned use
of the effluent is for irrigation.
248
-------
StephejrLvilie_, Texas Presently, 0.5 mgd of stabilization
ponalTf fluent is be ing discharged to the Bosque River. No
reasons for irrigation abandonment were given although
abandonment probably occurred prior to 1950.
uiJ.S. GOVMNMENT PRINTING OFFICE: 1973 546-31Z/157 1-3
249
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Rei. 't Ko.
w
WASTEWATER TREATMENT AND REUSE
BY LAND APPLICATION- VOLUME II
Pound, C. E., and Crites, R. W.
Metcalf § Eddy, Inc.
Palo Alto, California
1?. Spotr-oring O"jan'??.'--on
Environmental Protection Agency report number,
EPA-660/2-73-006b, August 1973.
P "j,
X. -ti
68-01-0741
;-V in.. .1. ---j , ,
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 tre ii la-
filtration-percolation is also a feasible method of land applical on,
Criteria for site selection, groundwater control, and managemer.'
techniques for high rate systems need further development.
i7a.
*Irrigation systems, *Design criteria, *Wastewater treatment, *Co?::: ,
*Groundwater recharge, *Public health, *Environmental effects, *b^.ag
treatment, *Industrial wastes, Climatic zones, Reclaimed water, Wastewater
disposal, Soil treatment, History, Crops, Percolation
05D, 04B, 02A
- J.9.. Si'-xttrity- f:'ass.
(Report)
2G. Security Class.
Page*
22. Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENTOFTHE INTERIOR
WASHINGTON. D. C. 2O24O
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