v>EPA
United States
Environmental Protection
Agency
Office of
Water Program Operations
(WH-546)
Washington, D.C. 20460
Reprint of
North Central Research
Publication 235
March 1978
Applications of Sludges
and Wastewaters
on Agricultural Land:
A Planning and
Educational Guide
-------
Disclaimer Statement
This report has been reviewed by the Environmental Protection Agency 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.
Notes
To order this publication, "Application of Sludges and Wastewaters on
Agricultural Land: A Planning and Educational Guide" (MCD-35), from EPA
write to:
General Services Administration (8FFS)
Centralized Mailing List Services
Bldg. 41, Denver Federal Center
Denver, CO 80225
Please indicate the MCD number and title of publication.
Multiple copies may be purchased from:
National Technical Information Service
Springfield, VA 22151
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March 1978
APPLICATION OF SLUDGES
AND WASTEWATERS
ON AGRICULTURAL LAND:
A Planning and Educational Guide
Edited by
Bernard D. Knezek and Robert H. Miller
Sponsored by North Central Regional Committee NC-118, Utilization and Disposal of Municipal,
Industrial, and Agricultural Processing Wastes on Land.
in cooperation with
Western Regional Committee W-124, Soil as a Waste Treatment System
Reprinted by
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER PROGRAM OPERATIONS
MUNICIPAL CONSTRUCTION DIVISION
WASHINGTON, D.C. 20460
MCD-35
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EPA Comment
This bulletin was selected for reprinting by the U.S. EPA Office of
Water Program Operations as one of a series of reports to help supply
detailed information for use in selecting, developing, designing, and
operating municipal wastewater treatment and sludge management systems.
The series will provide in-depth presentations of available information
on topics of major interest and concern related to municipal wastewater
treatment and sludge management. An effort will be made to provide the
most current state-of-the-art information available concerning sewage
sludge processing and disposal/utilization alternatives, as well as
costs, transport, and environmental and health impacts.
These reports are not a statement of Agency policy or regulatory
requirements. They are being published to assist EPA Regional Adminis-
trators in evaluating grant applications for constrution of publicly
owned treatment works under Section 203(a) of the Federal Water Pollution
Control Act as amended. They also will provide planners, designers,
municipal engineers, environmentalists and others with detailed
information on municipal wastewater treatment and sludge management
options.
Harold P. Cahill, Jr., Director
Municipal Construction Division
Office of Water Program Operations
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ABSTRACT
This bulletin was originally prepared under the sponsorship of two
regional committees representing the North Central and Western State
Agricultural Experiment Stations and cooperating elements of the U.S.
Department of Agriculture (the North Central Regional Committee NC-118,
Utilization and Disposal of Municipal, Industrial, and Agricultural
Processing Wastes on Land in cooperation with the Western Regional
Committee W-124, Soil as a Waste Treatment System). The report addresses
the application of agricultural processing wastes, industrial and municipal
wastes (i.e., sludges and wastewaters) on agricultural land as both a
waste management and resource recovery and reuse practice. The document
emphasizes the "treatment" and beneficial utilization of sludge and
wastewater as opposed to waste disposal. These objectives are achieved
through incorporation into well-designed and operated agricultural
production systems in ways that are compatible with maintaining the
soil's normal viability and productivity. Application of waste materials
to forested land, greenbelts, parks or golf courses, and land reclamation
projects are not specifically addressed, although many of the principles
discussed concerning their application to agricultural land would apply
to these situations as well.
Waste characterization, crop selection and management, site selection,
management and monitoring are addressed in a manner designed to lead
readers logically through the decision making process. Sample problems,
procedures, calculations and diagrams are incorporated into most sections.
In addition, public health and nuisance concerns, as well as public
acceptance, legal and economic considerations are discussed from a
cautious, though informative, point of view that also offers ideas for
dealing with such matters based upon experience gained from recent
projects.
The document does not provide in-depth design criteria and is not a
comprehensive design manual which could be used to design and manage a
land application system. It is, however, a useful planning tool, educational
guide, and information source for those who desire basic information
concerning land application systems. For more detailed and complete
design information and procedures, the reader should consult such sources
as the EPA Process Design Manuals, "Land Treatment of Municipal Wastewater"
(EPA 625/1-77-008; October 1977) and "Sludge Treatment and Disposal"
(EPA 625/1-74-006; October 1974 - currently being updated), the EPA
Technical Bulletin, "Municipal Sludge Management: Environmental Factors"
(EPA 430/9-77-004; October 1977), and the EPA Technology Transfer Design
Seminar publications on sludge and wastewater management available from
EPA/Technology Transfer, 26 West St. Clair, Cincinnati, Ohio 45268.
Robert K. Bastian
Municipal Construction Division
Office of Water Program Operations
U.S. Environmental Protection Agency
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North Central Regional Research Publication 235
October 1976
Application of Sludges and Wastewaters
on Agricultural Land:
A Planning and Educational Guide
Edited by
BERNARD D. KNEZEK and ROBERT H. MILLER
Sponsored by North Central Regional Committee NC-118, Utilization and
Disposal of Municipal, Industrial, and Agricultural Processing Wastes on
Land
in cooperation with
Western Regional Committee W-124, Soil as a Waste Treatment System
Agricultural Experiment Stations of Alas-
ka, Illinois, Indiana, Iowa, Kansas, Mich-
igan, Minnesota, Missouri, Nebraska,
North Dakota, Ohio, South Dakota, and
Wisconsin, and the U. S. Department of
Agriculture cooperating.
OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER
Wooiter, Ohio Research Bulletin 1090
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CONTENTS
Section
INTRODUCTION for Application of Sludges and Wastewaters
on Agricultural Land, by Bernard D. Knezek and Robert H. Miller 1
SITE SELECTION CONSIDERATIONS for Sludge and Wastewater
Application on Agricultural Land,
by George F. Hall, Larry P. Wilding, and A. Earl Erickson 2
ANALYSES AND THEIR INTERPRETATION for Sludge Application
to Agricultural Land, by Lee E. Sommers and Darrell W. Nelson 3
CROP AND SYSTEM MANAGEMENT for Sludge Application
to Agricultural Land, by Robert H. Miller 4
SELECTION OF THE SYSTEM for Sludge Application
on Agricultural Land, by Richard K. White 5
ANALYSES AND THEIR INTERPRETATION for Wastewater
Application on Agricultural Land, by Boyd G. Ellis 6
CROP AND SYSTEM MANAGEMENT for Wastewater Application
to Agricultural Land, by Arthur R. Wolcott and Ray L. Cook 7
SELECTION OF THE SYSTEM for Wastewater Application
on Agricultural Land, by Ernest H. Kidder 8
PUBLIC HEALTH AND NUISANCE CONSIDERATIONS for Sludge and Wastewater
Application to Agricultural Land, by Thomas P. Wasbotten 9
PUBLIC ACCEPTABILITY AND LEGAL CONSIDERATIONS for Sludge and
Wastewater Application on Agricultural Land, by Terry F. Glover 10
SITE MONITORING CONSIDERATIONS for Sludge and Wastewater
Application to Agricultural Land, by Paul A. Blakeslee 11
SELECTED BIBLIOGRAPHY 12
GLOSSARY OF TERMS 13
APPENDICES 14
Appendix A — Double Ring Infiltrometer Method
for Measuring Soil Infiltration Rates
Robert Taft Sanitary Engineering Center Percolation Test
Appendix B -- Sample Calculations to Determine Sludge
Application Rates on Agricultural Land
Appendix C -- Some Useful Factors and Conversions
Appendix D — PUBLICATIONS PERTINENT TO Application of Sewage
Sludge and Wastewater to Agricultural Land
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CONTRIBUTORS
Paul A. Blakeslee
Ray L. Cook
Boyd G. Ellis
A. Earl Erickson
Terry F. Glover
George F. Hall
Ernest H. Kidder
Bernard D. Knezek
Robert H. Miller
DarreH W. Nelson
Lee E. Sommers
Thomas P. Wasbotten
Richard K. White
Larry P. Wilding
Arthur R. Wolcott
Regional Sanitary Engineer, Municipal Wastewater Division,
Michigan Department of Natural Resources, Mason Building,
Lansing, Michigan 48926
Professor and Chairman Emeritus, Department of Crop and Soil
Sciences, Michigan State University, East Lansing, Mich. 48824
Professor of Soil Chemistry, Department of Crop and Soil
Sciences, Michigan State University, East Lansing, Mich. 48824
Professor of Soil Physics, Department of Crop and Soil
Sciences, Michigan State University, East Lansing, Mich. 48824
Associate Professor, Department of Agricultural Economics,
Utah State University, Logan, Utah 48322
Associate Professor, Department of Agronomy, The Ohio State
University and Ohio Agricultural Research and Development
Center, Columbus, Ohio 43210
Professor of Agricultural Engineering, Department of Agricul-
tural Engineering, Michigan State University, East Lansing,
Mich. 48824
Professor and Associate Chairman, Department of Crop and Soil
Sciences, Michigan State University, East Lansing, Mich. 48824
Professor, Department of Agronomy, The Ohio State University
and Ohio Agricultural Research and Development Center, Columbus,
Ohio 43210
Associate Professor, Department of Agronomy, Purdue University,
West Lafayette, Indiana 47907
Associate Professor, Department of Agronomy, Purdue University,
West Lafayette, Indiana 47907
Sanitary Engineer, Municipal Wastewater Division, Michigan
Department of Natural Resources, Mason Building, Lansing,
Mich. 48926
Associate Professor, Department of Agricultural Engineering,
The Ohio State University and Ohio Agricultural Research and
Development Center, Columbus, Ohio 43210
Professor, Department of Agronomy, The Ohio State University
and Ohio Agricultural Research and Development Center, Columbus,
Ohio 43210
Professor of Soil Science, Department of Crop and Soil Sciences,
Michigan State University, East Lansing, Mich. 48824
ii
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North Central Regional Committee NC-118
Utilization and Disposal of Municipal, Industrial,
and Agricultural Processing Wastes on Land
State Agricultural Experiment Stations
F. J. Wooding Alaska
S. W. Melsted Illinois
L. E. Sommers Indiana
J. J. Hanway (until June 30, 1976) Iowa
M. A. Tabatabai (since July 1, 1976) Iowa
R. Ellis, Jr Kansas
B. D. Knezek (until June 30, 1976) Michigan
L. W. Jacobs (since July 1, 1976) Michigan
R. G. Gast Minnesota
D. Sievers Missouri
M. Baker Nebraska
L. A. Douglas New Jersey
G. L. Pratt North Dakota
R. H. Miller Ohio
L. 0. Fine South Dakota
D. R. Keeney (until June 30, 1976) Wisconsin
L. M. Walsh (since July 1, 1976) Wisconsin
U. S. Department of Agriculture
D. H. Urie Forest Service
T. M. McCalla Agricultural Research Service (Nebraska)
J. F. Parr, Jr Agricultural Research Service
A. S. Newman Cooperative State Research Service
U. S. Environmental Protection Agency
C. Enfield
J. Ryan
Administrative Advisors
R. W. Kleis (until June 30, 1976) Nebraska
S. R. Aldrich (since July 1, 1976) Illinois
iii
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Western Regional Committee W-124
Soil as a Waste Treatment System
State Agricultural Experiment Stations
W. H. Fuller Arizona
A. L. Page, P. F. Pratt, and J. E. Vlamis California
B. R. Sabey Colorado
Y. Kanehiro Hawai i
S. M. Beck Idaho
J. R. Sims » Montana
L. Chesnin Nebraska
R. A. Young Nevada
V. V. Volk Oregon
R. W. Miller Utah
D. F. Bezdicek and D. 0. Turner Washington
H. W. Hough Wyoming
D. R. Keeney Wisconsin
U. S. Department of Agriculture
R. E. Luebs, B. D. Meek, and 0. H. Smith Agricultural Research Service
D. K. Nettleton Soil Conservation Service
A. S. Newman Cooperative State Research Service
U. S. Environmental Protection Agency
R. E. Thomas
Administrative Advisor
R. J. Miller Idaho
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Section 1
INTRODUCTION
for Application of Sludges and Wastewaters
on Agricultural Land
(A Planning and Educational Guide)
Bernard D. Knezek and Robert H. Miller
Under the Federal Water Pollution Control Amendments of 1972, land application
is recognized as an alternative method for effecting stages of wastewater treatment
and for ultimate disposal of solid wastes. For certification and shared-cost funding
under this legislation, a waste treatment proposal must include evidence that the
plan is based on "the best practicable technology" and "the most cost effective
method(s) over the life of the works." Requirements for compliance are phased over
periods of years and advance by stages toward the goal of "eliminating discharge of
all pollutants into navigable surface waters by 1985."
The idealized goal of "zero discharge" is neither practical nor wholly desirable.
Nevertheless, it is to be expected that the quality and permissible uses of waters
originating in waste treatment operations will come under increasing regulation at
all levels of government. Discharge standards ultimately adopted will vary with
background levels in natural waters from one locality or region to another and will
be subject to periodic revision as new technologies evolve for assessing environmen-
tal impact and for effecting rational control.
The capacity of soils to receive wastewater and sludges and to inactivate con-
taminants varies greatly, depending upon a variety of soil, plant, and climatic fac-
tors. Generally, most well-aerated soils are quite efficient in organic matter
conversion so that BOD loading is not a direct problem. Certain nutrients (such as
nitrate) which are produced by organic breakdown may become a problem at high loading
rates. Soils with high water infiltration capacity, which would allow large water
loading rates, may be ineffective in trapping nutrients even though BOD elimination is
rapid. Therefore, the soil selected for waste application on land must be chosen on
the basis of waste characteristics, operation and management aspects, cropping sys-
tems, and other factors which make each decision an individual undertaking. Usually,
the best soil for waste application is dictated by a necessary balance between poten-
tial soil loading rates and potential environmental contamination.
Emphasis in this document is directed toward utilization of agricultural proces-
sing, industrial, and municipal wastes through application on agricultural land.
Animal wastes are covered in a separate document. (21)
Several basic points need to be clarified to establish the context within which
all of the contributions of this document have been developed.
1. Land is a valuable natural resource and the viability and productivity
must not be endangered during application of wastes.
2. The system must be managed so that normal agricultural production can
be maintained without sacrificing crop quality or yield.
3. A balanced system must be established so that the finite limits of the
regeneration processes of the soil are not exceeded.
1.1
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4. Primary emphasis Is upon utilization of the usable resources in the waste
constituents rather than providing a disposal site.
Who will be the primary users of the information provided by the numerous pro-
fessionals who have contributed to this document? Throughout its compilation, the
editors have considered a broad potential audience. Personal experiences of both
have shown that a broad spectrum of individuals and professions naturally become in-
volved when a municipality makes a decision to consider land application of waste-
waters and/or sludges; e.g., municipal officials, other community leaders, health
officials, sanitary engineers, consulting engineers, farmers, extension agents, soil
conservation personnel, mass media representatives, teachers, and local citizens with
a desire to be better informed.
This document is not intended to provide final design criteria and information
.which could be used to totally design and manage a land application system. Rather,
it is to be used as a planning tool by people who must plan, as an educational tool
for those who must educate, and as an information vehicle for those who desire infor-
mation. For this reason, the individual contributions have been organized in a
manner which it is hoped will lead interested people logically through the decision-
making or educational processes. A loose-leaf format was selected to allow for up-
dating of various sections as more information becomes available without the need
to reprint the entire document. This will undoubtedly happen frequently in the next
5 years in the area of heavy metals and nitrogen reactions, where considerable
research is rapidly reaching fruition.
Application of these same wastes to forested land, greenbelts, parks, golf
courses, or land reclamation areas is not considered specifically. Yet, the prin-
ciples involved and discussed can often be applied to these locations as well.
Bernard D. Knezek is Professor and Associate Chairman, Department of Crop and
Soil Sciences, Michigan State University, East Lansing, Mich. 48824.
Robert H. Miller is Professor, Department of Agronomy, The Ohio State University
and Ohio Agricultural Research and Development Center, Columbus, Ohio 43210
-1-.-2-
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Section 2
SITE SELECTION CONSIDERATIONS
for Sludge and Wastewater
Application on Agricultural Land
George F. Hall, Larry P. Wilding, and A. Earl Erickson
Site selection criteria consider those characteristics of the soil and land-
scape which will lead to the renovation of sludge and wastewater solids without
creating environmental problems outside the site perimeter. The basic objective
is to apply sludge and/or wastewater to the soil in such a manner that the soil can
assimilate the wastes and prevent the wastes and harmful by-products from moving on-
to adjacent land, into flowing water, or into the groundwater beneath the land.
The site selection criteria for wastewater renovation are in many ways very
similar to those for sludges. There are, however, some very important differences.
Three basic interrelated parameters will be discussed relative to the best possible
site selection. These parameters include landscape features, soil parent material
including geologic characteristics, and properties of the soil. It must be empha-
sized that soils and landscapes are very complex and the principles given here are
only guidelines for the selection of a sludge and/or wastewater application site.
On-site evaluation of soil and landscape conditions is essential prior to final site
selection. These on-site investigations should be made by qualified soil scientists
and supplemented in some cases by specialists such as geologists, hydrologists, engi-
neers, etc. Assistance can be obtained from a number of organizations in each state,
including:
• U.S. Department of Agriculture, Soil Conservation Service
State Departments of Natural Resources or comparable agencies
• State Agricultural Experiment Stations, or Colleges and Universities with
Departments of Agronomy or Soil Science
Cooperative Extension Service
Professional consultants with training and experience in the field of
agronomic soil science
U. S. Geological Survey.
Site Selection
An ideal site for sludge and wastewater utilization would have the following
landscape, parent material, and soil characteristics. Keep in mind, however, that
less than ideal sites may sometime be usable with proper design and management.
Landscape
• A closed or modified closed drainage system (Fig. 2.1)
• Slopes less than 4%; steeper gradients may be acceptable on coarse-textured
•soils or where management practices (see Sections 4 and 7) or application
methods (see Sections 5 and 8) reduce erosion hazards.
2.1
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FIG. 2.1.--Diagrammatic representation of open and closed drainage systems.
GLACIAL TILL OR
IMPERMEABLE
BEDROCK
Plowpan
B horizon
Fragipan
Cemented hard pan
FIG. 2.2.--Diagrammatic cross-section of a sloping landscape showing the position
of various restrictive layers.
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Parent Material
Medium-textured materials; finer-textured or high bulk density materials
are suitable for sludges if managed properly and may be suitable for waste-
waters if overland flow is used.
High pH's and/or free carbonates (lime).
Bedrock and unconsolidated substrata, when present, should be free of coarse
conducting layers or conduits, and should always be at least 3 or 4 feet
below the soil surface.
Soils
• High surface infiltration capacity and moderate subsoil permeability. (See
Appendix A for methodology.)
• A soil thickness of at least 3 feet without restrictive layers.
• Well or moderately well-drained soil conditions to provide oxidizing con-
ditions throughout most of the year; less well-drained soils if adequately
tiled.
• Moderate to high moisture supplying capacity (15 to 20 percent by volume).
• Soil pH values ranging from 6.5 to 8.2.
• Medium and high levels of organic matter in the surface horizon.
A more detailed discussion of these site selection criteria is contained in the
following paragraphs.
Landscape Position
Position on the landscape is of major importance because it asserts a major
influence on surface and subsurface water movement (hydrology of area); it influences
the amount of soil erosion and therefore the amount of sludge, wastewater, and by-
products which may move off the site; and it asserts a secondary influence through
its control on the kinds of soils found in the watershed.
Two general landscape drainage systems exist; the open and the closed system
(Fig. 2.1). The open drainage system of most humid and subhumid areas permits the
movement of sediment and soluble material from a given site to the watercourse and
then to the major sediment loads in streams and rivers.
In contrast, the closed drainage system of some arid and semiarid areas is a
landscape where essentially all products derived within the perimeter are trapped
within the system and are not transmitted to major streams or underground water
supplies. Excess water is ponded and evaporates or filters for short distances
through the soils in these areas. These systems contribute little to the pollution
of the environments outside their perimeter.
In the selection of a site for sludge utilization, a landscape consisting of or
approaching a closed drainage system is most desirable. Containment of the sludge
and its by-products is necessary until the risk from potential environmental contami-
nants has been removed by physical, chemical, or biological reactions of the soil.
Z.3.
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A modified closed system can easily be developed on a nearly level landscape by the
erection of small ridges across the outlet of the drainage basin.
A site for wastewater application should be a modified open system where pro-
visions are made for the interception and removal of water after renovation.
In most landscapes, the surface soil is underlain by horizons or strata which
are less permeable (Fig. 2.2) and which restrict water movement and renovative cap-
abilities. Examples of less permeable subsurface and subsoil horizons are:
finer textured B horizons (claypans)
compaction pans (plowpans)
fragipans (silt pans)
dispersed subsoils (chemical pans)
• dense glacial till, shale, siltstone, and residuum overlying limestone
duripans (silica-cemented hardpans)
petrocalcic horizons (caliche or lime cemented hardpan)
ironstone sheets.
Where these layers occur, much of the water moves down to the less permeable
layer and then laterally downslope. Where slopes become more concave, or where the
less permeable layer comes closer to the surface, seeps occur (Fig. 2.2).
Shaping of landscapes may cause some of the above conditions. At any proposed
site requiring major shaping, the characteristics of the subsoil horizons should
be carefully evaluated to determine the types of chemical and physical character-
istics which may be exposed or brought closer to the surface during the shaping
operation.
Soils on convex landscape positions or on steep slopes usually are well drained,
well oxidized, thinner, and subject to erosion. Soils on concave landscape positions
and on broad flats are often more poorly drained, less well oxidized, and deeper.
Water and sediment from higher positions move to these low-lying landscape areas.
Soil and Parent Material
On land used for sludge and/or wastewater applications, the soil functions as a
natural filter and as a medium for the biological and chemical reactions which result
in renovation of these waste materials. The suitability of a site is therefore a
function of the physical, chemical, and mineralogical characteristics of the soil.
These are discussed in detail below:
Texture
Texture of the soil and parent geologic material is one of the most important
aspects of site selection because it influences infiltration rate, subsoil percola-
tion rate, moisture holding capacity, and adsorption reactions for waste components.
2.4
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Fine textured soils include clay, sandy clay, silty clay, clay loam, and silty
clay loam. Medium textured soils are silt, silt loam, loam, and sandy clay loam.
Coarse textured soils include sand, loamy sand, and sandy clay loam. Definitions
of textural terms can be found in the U.S.D.A. Soil Survey Manual (25).
In most soils, the clay fraction represents only about 10 to 40% of the total
soil, but because clays are plate-shaped and have high surface areas, this component,
along with organic matter, governs most physical and chemical reactions in the soil.
These electrically charged particles have structures and properties which permit
their large surface areas to hold various nutrients (including phosphates), heavy
metals, and pesticides. Nitrate, on the other hand, is not held to these surfaces
and is mobile.
Infiltration and Permeability
Fine textured soils often have as much pore space as coarse textured soils but
pores in fine textured soils are very small and transmit water very slowly. As a
result, most water movement in fine textured soils is along the surfaces of the soil
aggregates and cracks rather than through the entire soil volume. When fine textured
surface materials are wetted and the large transmitting channels closed, the infiltra-
tion rate becomes very slow. Percolation rate in the subsoil follows a similar pat-
tern in medium and fine textured materials. Swelling of the clay fraction, particu-
larly high shrink-swell clay minerals, effectively seals the soil against further
downward movement of water. This sealing causes the water to pond on top of the sub-
soil which in turn favors runoff and erosion from the landscape. One should be cau-
tious in evaluating a site for sludge application on fine textured soil to assure
that the amount of water added will infiltrate. Failure to achieve rapid infiltra-
tion could result in temporary anaerobic conditions and increased risk of odors.
If poorly and imperfectly drained soils are to be used for renovation of waste-
water by spray irrigation, drainage systems will be needed. These drainage systems
should be placed at greater depths and at more frequent intervals than in normal
agricultural drainage design. This will insure several feet of aerobic soil for
normal crop growth and adequate wastewater renovation. If artificial drainage is
provided, monitoring of drainage water should be undertaken for the first season to
insure that the treatment system is performing as designed.
Recently there has been considerable interest in utilizing overland flow for
wastewater renovation on fine textured soils where topography is favorable (see
Section 8). Design criteria for determining both the percent and length of slope
for proper renovation are still being developed.
In contrast to the fine textured soils, coarse textured soils have many large
interconnecting pores which allow water to move rapidly through the soil. Unless
the coarse textured material is underlain by a finer textured zone (such as a finer
textured subsoil, pan, or parent material), water carrying suspended soluble compo-
nents from sludges and wastewaters can move downward to the aquifer and may cause
contamination of a public or private water supply.
If only coarse textured soils are available, improved renovation can be achieved
by limiting the quantity of wastewater applied at any one time. This allows more
time for plant uptake of nutrients and for the soil chemical and biological reactions
important for renovation to occur. Under intensive management and proper conditions,
wastewater renovation has also been achieved in coarse textured soils by the rapid
infiltration-percolation method (5).
2.5
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Infiltration and permeability rates tend to increase with increased organic
matter content. Organic matter improves soil aggregation and porosity and allows
water to be transmitted more rapidly. In addition, organic material in the surface
helps prevent crusting, particularly in silty soils.
Biotic factors also contribute to variability in permeability. In areas which
are forested or which have recently been cleared, old root channels permit water
and potential pollutants to move through the surface soil more rapidly. Burrowing
insects and animals also create channels. Following a heavy rainfall, water may
move through the soils in these biotic channels rather than through the soil profile.
This effectively reduces the renovative capacity of the soil.
Moisture Holding Capacity
Soil texture and bulk density (soil weight per unit volume) of the soil are
important factors in determining the available moisture holding capacity. This capac-
ity is a measure of the moisture a soil can hold for plant use. It also gives an
index to the amount of moisture a soil can absorb. Medium textured soils with bulk
densities of less than 95 lb./ft.3 have available moisture holding capacities of 15
to 20%. Such soils, when dry enough that plants permanently wilt, will absorb 9 to
12 inches of water from sludge, wastewater, or rainfall in the upper 60 inches be-
fore transmitting water to the underlying aquifer. Finer and coarser textured soils
have lower moisture holding capacities and thus would not retain as much water.
Bulk Density
In all soils, the moisture holding capacity and percolation rate decrease as
bulk density increases. Additionally, plant root growth is limited in soils with
high bulk densities. Bulk densities greater than 100 lb./ft.3 are restrictive to
moisture movement and plant root growth. Two common situations where these high
bulk density values may occur are in fragipans and in unweathered glacial till.
Often in the spring of the year, these very dense zones will limit vertical water
movement to such an extent that water will be ponded above these horizons and a
perched water table situation develops. Dense zones or horizons limit the thickness
of the soil as a renovation medium, and favor anaerobic conditions above the pan
when waterlogging occurs. Soil compaction and ^increased bulk densities may occur
when sludge application equipment is used on excessively wet soils (see Section 5).
Soil Reaction
The glacial till and loess from which most of the soils of the North Central
Region are developed were calcareous when deposited. As a result of leaching and
soil development, carbonates have been removed from the surface. Soil reactions
near neutral (pH values 6.5-7.5) are important for the immobilization of heavy metals
and phosphates which occur in sludges and wastewaters. Most soils of the Western
United States, since they have soil reactions near neutral, have suitable soil re-
actions to immobilize heavy metals and phosphates. Soils with low pH's (<6.5) must
be amended with lime prior to applications of sludge to raise the pH. Medium tex-
tured soils with free carbonates at less than 4 or 5 feet are very effective in im-
mobilizing heavy metals and phosphates which might move downward, particularly in a
closed drainage system.
Restrictive Layers
Soils are not uniform either vertically or horizontally. In cross-section, the
soil can be seen as a series of layers of differing permeability. A number of these
layers in different soils are restrictive to water movement.
2.6
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The most common restrictive layer is the horizon of clay accumulation (clay pan)
which occurs in most upland soils. A second restrictive layer is the plowpan, or
traffic pan, which may form 6 to 10 inches below the surface as a result of traffic
of heavy equipment (either farm or construction) over the surface. Fragipans (silt
pans) are a third type of restrictive zone resulting from natural soil-forming proces-
ses in silty or loamy materials. These compact pans start at depths of 15 to 40
inches and have bulk densities ranging from 95 to 125 lb./ft.3.
A fourth type of restrictive zone is the dispersed subsoil situation or chemical
pans. These restrictive layers result from the dispersion of individual soil parti-
cles so that the soil mass has lost most of its structural characteristics and water
conducting channels. The main chemical responsible for the dispersion is sodium.
Most soils with a major clay component of montmorillonite and a significant amount
of sodium have restrictive layers.
A fifth type of restrictive layer is the result of dense parent material or
bedrock such as glacial till, shale, siltstone, etc. Rock-like layers can also form
as the result of precipitation of silica (duripans), carbonate (petrocalcic and cal-
cic horizons), or iron (ironstone layers).
Soil Variability
In selecting any site for sludge and/or wastewater renovation, it is important
to consider soil variability. Soils developed from loessial (wind-blown silt) mate-
rials are most uniform, while those derived from glacial outwash or interstratified
bedrock materials are most variable. Glacial till may also be quite variable, parti-
cularly when in close proximity to glacial outwash deposits. The magnitude and type
of soil variability may determine the suitability of an area for sludge and/or waste-
water application and are important in determining the pattern and extent of sam-
pling for site evaluation. On-site investigation of a proposed site is essential to
determine the magnitude of soil variability. Failure to do so could result in some
unexpected environmental or management problems.
Sampling
Within every soil series there is a given range in physical, chemical, and
mineralogical properties. Soil analyses in Soil Survey Reports represent the central
concept of the soil, but soils at a proposed site may have somewhat different charac-
teristics. Therefore, it is highly recommended that analyses be made of the soils
found at the site. Useful laboratory analyses include particle size, organic matter,
pH, cation exchange capacity, moisture holding capacity, and bulk density. On-site
evaluation should include the measurement of percolation, permeability, and water
table levels at various times of the year. If clay mineralogy of the soils is not
well documented, this analysis should also be made. In most of the Western United
States and in the central and western portion of the North Central Region where high
sodium levels are commonly found in the soils, electrical conductivity of the samples
should also be determined. Soil samples from the actual site also provide base line
data from which soil changes may be evaluated after sludge and wastewater application.
Available Resource Material
The preceding discussion has outlined a number of properties of the landscape,
soils, and soil parent materials which are important in evaluating a site for sewage
sludge and/or wastewater application. This discussion is not sufficient for making
a final decision on site location. Many other resources of published material and
2,7
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personnel are available and should be consulted before a final decision is made.
Some sources of qualified personnel were discussed on page 2.1.
Published reports on soils, geology, topography, and hydrology are available
;for most areas in the country. Emphasis is being placed on publication of more re-
ports for areas undergoing urban expansion. Among the most useful standard reports
available are the Soil Survey Reports produced by the National Cooperative Soil Survey
and published by the U.S. Dept. of Agriculture. Each report contains a detailed map
showing the areal distribution of soils in the area, along with physical, chemical,
and mineralogical data and/or estimates for all the soils. In many areas, maps may
be available even though the final report has not been printed. Often an interim
report containing soil descriptions and data is available prior to the final report.
A soils map is developed by soil scientists examining the entire area, and is useful
for general planning purposes. It is not, however, detailed enough so that it can
be used without on-site inspection by qualified personnel. In areas where a soil
survey is not available, a soils map can be requested by contacting the local Soil
Conservation Service office.
In some areas, geologic reports on a quadrangle base are available. These re-
ports give details on the geologic strata in the area, including a map and discussion
of surficial deposits. Some chemical and physical data on the various strata are
also included in most of these reports. These reports are particularly useful in
identifying aquifers and thus areas where sands, gravel, limestone, and other rapid
conductors of water are located. Topographic maps of the 7-1/2 minute quadrangle
series are available from the U.S. or State Geological Survey for most of the country.
These maps show contour lines and cultural features, including roads, houses, and
lakes. In many areas, special reports have been made on groundwater hydrology by the
U.S. or State Geological Survey or by local groups interested in knowing the ground-
water potential.
On-site inspection by trained professionals is a must for all sludge and waste-
water application sites. The qualified soil scientist can provide the user with more
detailed information on the limitations of the soils at the site and can identify
areas of soils that differ from those delineated on a standard soils map accompanying
Soil Survey Reports. Qualified soil scientists may be available at the local Soil
Conservation Service office, the State Department of Natural Resources, the State
Agricultural Experiment Station, or at local professional consulting firms. The
Cooperative Extension Service usually has personnel in the county who can assist in
determining suitable sites. Geologists should also be consulted in cases where in-
stallations are to be made to depths greater than 5-6 feet, or where there may be
questions concerning a shallow or complex aquifer. Help from geologic consultants
is available from the U.S. or State Geological Survey and professional engineering
consulting forms.
George F. Hall is Associate Professor, Department of Agronomy, The Ohio State
University and Ohio Agricultural Research and Development Center, Columbus, Ohio
43210.
Larry P. Wilding is Professor, Department of Agronomy, The Ohio State University
and Ohio Agricultural Research and Development Center, Columbus, Ohio 43210.
A. Earl Erickson is Professor of Soil Science, Department of Crop and Soil
Sciences, Michigan State University, East Lansing, Mich. 48824.
2.8
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Section 3
ANALYSES AND THEIR INTERPRETATION
for Sludge Application to Agricultural Land
L. E. Sommers and Barrel 1 W. Nelson
Sewage sludge is a general term used to describe a variety of materials, com-
monly a suspension containing 1 to 10% solids, produced during treatment of
wastewater. Sludges generated during the secondary stage of wastewater treatment
are normally "activated sludges." Solids separated from the wastewater during
primary treatment (primary sludge) are subjected to anaerobic digestion, producing
what is generally referred to as "sewage sludge" or "anaerobically digested sludge".
In some treatment systems, both the primary and secondary sludges are digested
anaerobically. In addition, wet-air oxidation processes or lime (CaO) treatment
are being used in some treatment plants as alternative methods for stabilization
of primary and/or secondary sludges. In accordance with recent policies of
U.S. EPA, the recommendations discussed herein refer to application of stabilized
sludges on land. The principal reason for requiring stabilization of sludges is
the potential threat of dispersing pathogens contained in "raw" sludges. Additional
types of sludges will require consideration in the future, such as tertiary
sludges resulting from lime or alum treatment of secondary wastewater.
In general, the majority of sludge applied to land will be either anaerobically
or aerobically digested sewage sludge. After digestion, sewage sludge may be
further processed to reduce the water content by vacuum filtration or centrifugation,
resulting in a sludge "cake" containing 30-40% solids. In many cases, sewage sludge
will be applied to land as a suspension containing from 1 to 10% solids (i.e.
the form exiting the digester or settling tank). The dewatering of sludge not only
influences the economics"of sludge disposal but it also alters the chemical composition
of the sludge and thus the rate of application on agricultural land.
It should be realized that sewage sludge is a very heterogenous material, vary-
ing in composition from city to city and from day to day in the same city. Thus,
before a serious attempt is made to develop plans for sludge application on agri-
cultural land, considerable thought should be given to obtaining representative
samples and making arrangements for accurate chemical analysis of the sludge.
Sludge Analyses
Sample Collection
Preliminary analyses can be made from a single grab sample, but more detailed
sampling is needed. For calculation of application rates, separate samples of the
sludge should be collected once per 2-3 months for a period of 6 to 12 months in
order to obtain a representative analysis of the material to be considered for land
application. The most desirable sampling scheme involves obtaining samples based
on flow so that the flow-weighted average chemical composition can be determined.
3.1
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One liter (or qt.) of sample should be stored in a plastic or glass container so
that evaporation of water is prevented. If dry sludge is used, these precautions
are not necessary and a plastic bag will suffice for sample storage and transportation
Samples should be subjected to chemical analysis as soon as possible. If storage
is required, it is recommended that samples be frozen or stored at 33-36 F. If
more than 1 day will elapse between sample collection and cold storage, enough
hydrochloric acid should be added to slurry samples to bring the pH value to
between 0 and 1.
Sludge Analysis
Sewage sludges contain a wide variety of materials, including plant nutrients,
organic materials, oils, greases, and trace metals. The metal content of sludge is
especially important because many metals are essential for plant growth at small
concentrations, but are toxic at high concentrations. A complete analysis of
sewage sludge is a very involved process requiring considerable effort. Fortunately,
a complete analysis is not required to make a recommendation for rates of sludge
application to agricultural lands. The sludge analysis recommendations which
follow should be considered tentative since future information may indicate that
additional elements should be included or that some of the elements included need
not be determined.
Necessary Analyses
Analyses required of all sludge samples and the suggested analytical methods
are shown in Table 3.1. Since the solids content of sludges varies from batch to
batch, all composition data must be expressed on an oven-dry solids basis. The
following parameters must be determined to develop recommendations for application
rates on agricultural soils.
TABLE 3.1 Methods for Sludge Analysis .
Parameter
Suggested Method
Percent solids
Total N (nitrogen)
NHt-N (ammonium)
N03-N (nitrate)
Total P (phosphorus)
Total K (potassium)
Copper (Cu, zinc (Zn), nickel (NT)
lead (Pb,) and cadmium (Cd)
Drying at 105°C for 16 hrs.
Micro-Kjeldahl and S.D.f
Extraction with potassium chloride and
S.D.
Extraction with potassium chloride and
S.D. after reduction
Nitric acid-perchloric acid digestion
and colorimetry
Nitric acid-perchloric acid digestion
and flame photometry
Nitric acid-perchloric acid digestion
and atomic absorption *•
* References (4,11,20)
t S.D., steam distillation and titration of distillate with standard sulfuric acid.
Colorimetric methods may be used for ammonium and nitrate.
t Background correction (e.g., deuterium or hydrogen lamp) may be needed for
cadmium, nickel and lead.
3.2
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Additional Analysis
The following elements may be of concern in special instances, but in most
sewage sludges which are encountered they will not influence the rate of applica-
tion of sludge to land: selenium, cobalt, chromium, arsenic, boron, iron, aluminum,
mercury, silver, barium, sulfur, calcium, magnesium, sodium, molybdenum,
inorganic carbon, and organic carbon. (Refer to Section 11 for information
qualifying the above list of elements). With the exception of sulfur, carbon,
and boron, all analyses listed above can be accomplished with atomic absorption
spectrophotometry provided the sludge contains significant amounts of the element.
In most cases the elements arsenic, selenium, boron, chromium, and mercury are of
greatest importance in industrial wastes; however, some municipal sludges may
contain elevated levels of these metals if industrial wastes are added to the sew-
age system. In these cases the industrial wastewater should be exajnined and based
on this information a decision should be made as to which sludge parameter is of
greatest concern. Even though some of the above elements may be present in high
concentrations in sludge, they do not appear to limit crop growth to the extent
of the elements listed under Necessary Analyses.
Considerations for Applying Sewage Sludge on Agricultural Land
The following information is needed prior to calculating the rate of sludge
application:
Sludge composition (see Table 3.1)
Soil pH, cation exchange capacity, and lime requirement to adjust soil
to pH 6.5
Soil test for available P and K; P and K fertilizer recommendation for crop
to be grown.
Crops to be grown.
The rate of sludge application to land is based on the nitrogen requirement
of the crop grown and the metal content of the sludge. If the sludge being
applied has a low metal content, then it is possible to use sludge as a nitrogen
fertilizer material. However, if the sludge contains high concentrations of Cd
then the sludge may be used as a supplemental nitrogen source only. In either
case it may be necessary to use commercial fertilizer materials to furnish potassium
for crop growth. The ranges of nitrogen, phosphorus, and potassium contents
typically found in anaerobically digested sewage sludges are shown in Table 3.^.
TABLE 3.2 Composition of Representative Anaerobic Sewage Sludges.
Component
Range
Lb/Ton'
Organic nitrogen
Ammonium nitrogen
Total phosphorus
Total potassium
1% - 5%
1% - 3%
1.5% - 5%
0.2% - 0.8%
20 -
20 -
30 -
4 -
100
60
100
6
* Percent of oven-dry solids
t Lb./ton dry sludge
3,3
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After addition to soil, sewage sludge is slowly decomposed, resulting in re-
lease of nitrogen available for plant growth. Available data suggest that 20%
of the organic nitrogen is converted to plant available forms the first year and
that 3% of the remaining organic nitrogen is released each year for at least three
subsequent years. Thus, plant available nitrogen is released for several years
after sludge has been added to soils. For example, decomposition of a sludge con-
taining 3% organic nitrogen applied at 10 tons/acre/year for 3 years will release
41 Ib. of nitrogen the fourth year. Thus, sludge application rates are based on
the quantity of readily available nitrogen in sludge (i.e., NHj and NO.) and on
the amount of nitrogen released during sludge decomposition in soil. The data
presented in Table 3.3 is based upon N mineralization rates of 20, 3, 3, and 3%
for years 1, 2, 3, and 4 after sludge application. The exact percentages used for
organic N mineralization in sludge treated soils are undoubtedly a function of
sludge, soil and climatic conditions. In more temperate climates, the percentages
are likely greater than those used herein. Nevertheless, a decay series for
organic N mineralization should be employed for calculating sludge application
rates based on N required for crop growth. An additional consideration in sludge
application rates is the method of application. For surface applications of
sludge, approximately 50% of the NHt-N applied will be volatilized as NH~, re-
sulting in increased application rates. If sludge is incorporated immediate!v
(e.g., injected), then available N applied in sludge should equal the fertile
N recommendation. When sludges are added to soils at N utilization rates, the
amount of P added exceeds that required for crop growth. Excess available P in
soils may be related to decreased soybean yields encountered in some experiments.
Based on the limited data available, the level of available phosphorus in soils
receiving sludge should be checked and serious consideration given to discontinu-
ing sludge applications if available phosphorus exceeds 1500 Ib/acre.
The criteria used to prevent metal injury from sludge application on land
are based upon the total amount of Pb, Cu, Zn, Ni, and Cd added in sludges.
Whereas nitrogen commonly limits the annual application rate of sludge, metals
in sludge will determine the length of time a given acreage can receive sludge.
The upper limit for metal addition is given in Table 3.3 The current version of
Table 3.3 differs from the first edition of this paper in that the limits for
Ni have been increased by a factor 2.5. This increase in Ni limits reflects
recent research data indicating that Ni toxicity to crops will not be a problem
in soils maintained at pH > 6.5, as required for soils receiving sewage sludges.
The limits for Pb are not based on potential toxicity of Pb to plants but rather
to protect both animals and humans from Pb exposure through direct ingestion of
soil receiving sludge. In addition to the maximum accumulation of Cd shown in
Table 3.3, the rates of sludge application should result in no more than 2 Ib.
of Cd per acre being applied on an annual basis. It must be emphasized that
soil pH must be maintained at pH > 6.5 after sludge applications are discontinued.
If sludge applications are limited by Zn, Cu or Ni, metal toxicities to plants
could result if the soil is allowed to become acid in the future.
The use of CEC in Table 3.3 does not imply that metals added to soils in
sludge are present as exchangeable cations. Rather, the ability of a soil to
maintain added metals in a form unavailable for plant uptake is related to the
organic matter, clay and hydrous oxide content of the soil. As these soil para-
meters increase in concentration, increases in CEC result. Thus, CEC was chosen
as a single, easily measured soil property which is proportional to the ability
of a soil to minimize metal effects on crops.
3.4
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TABLE 3.3 Total Amount of Sludge Metals Allowed on Agricultural Land.
Metal
Pb
Zn
Cu
Ni
Cd
Soil
0 - 5
500
250
125
125
5
Cation Exchange Capacity
5-15
Maximum Amount of Metal
1000
500
250
250
10
(meq/100 g)*
> 15
(Lb/Acre)
2000
1000
500
500
20
Determined by the pH 7 ammonium acetate procedure.
The values in Table 3.3 are the total amounts of metals which can be added
to soils. With metal contaminated sludges, one of the above criteria may be
met with a single application, whereas 5, 10 or 20 applications may be needed for
"clean" domestic sludges. Furthermore, when the metal limits are reached, sludge
application must be terminated. A soil pH > 6.5 must be maintained in all sites
after sludge is applied to reduce the solubility and plant uptake of potentially
toxic heavy metals.
Calculation of Annual Application Rate
Step 1. Obtain N requirement for the crop grown from Table 3.4 or obtain
N fertilizer recommendation from Cooperative Extension Service
or soil analysis laboratory.
Step 2. Calculate tons of sludge needed to meet crop's N requirement.
a. Available N in sludge
% Inorganic N (1^) = (% NH4-N) + (% N03-N)
% Organic N (NQ) = ( % total N ) - ( % inorganic N )
i) Surface applied sludge
Lb available N/ton sludge = (% NH4-N X 10) + {% N03.-N..X 20)
+ (.% N X 4)
ii) Incorporated sludge °
Lb available N/ton sludge = ( % NH4-N X 20) + (* NO-j-N X 20)
b. Residual sludge N in soil °
If the soil has received sludge in the past 3 years, calculate
residual N from Table 3.5.
c. Annual application rate
. , . . crop N requirement - residual N
i) Tons sludge/acre = Lb\ available N/ton sludge
..« _ , . , 2 Ib. Cd/acre
n) Tons sludge/acre = ppm cd x .002
iii) The lower of the two amounts is applied.
3.5
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Table 3.4.-- Annual Nitrogen, Phosphorus, and Potassium Utilization by Selected
Crops.*
Crop
Yield Nitrogen
Phosphorus
Potassium
Lb. per Acre
Corn
Corn silage
Soybeans
Grain sorghum
Wheat
Oats
Barley
Alfalfa
Orchard grass
Brome grass
Tall fescue
Bluegrass
150 bu.
180 bu.
32 tons
50 bu.
60 bu.
8,000 Ib.
60 bu.
80 bu.
100 bu.
100 bu.
8 tons
6 tons
5 tons
3.5 tons
3 tons
185
240
200
257t
336t
250
125
186
150
150
450+
300
166
135
200
35
44
35
21
29
40
22
24
24
24
35
44
29
29
24
178
199
203
100
120
166
91
134
125
125
398
311
211
154
149
Values reported above are from reports by the Potash Institute of America and
are for the total above-ground portion of the plants. Where only grain is re-
moved from the field, a significant proportion of the nutrients is left in the
residues. However, since most of these nutrients are temporarily tied up in the
residues, they are not readily available for crop use. Therefore, for the purpose
of estimating nutrient requirements for any particular crop year, complete crop
removal can be assumed.
^Legumes get most of their nitrogen from the air, so additional nitrogen sources
are not normally needed.
Table 3.5.--Release of Residual Nitrogen During Sludge Decomposition in Soil
Years After
Sludge Application
Organic N Content of Sludge, %
2.0
2.5
3.0
3.5
4.0 4.5
5.0
1
2
3
Lb. N Released per Ton Sludge Added
1.0
0.9
0.9
1.2
1.2
1.1
1.4
1.4
1.3
1.7
1.6
1.5
1.9
1.8
1.7
2.2
2.1
2.0
2.4
2.3
2.2
3.6
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Step 3. Calculate total amount of sludge allowable.
a. Obtain maximum amounts of Pb, Zn, Cu, Ni, and Cd allowed for
CEC of the soil from Table 3.3 in Ib./acre.
b. Calculate amount of sludge needed to exceed Pb, Zn, Cu, Ni, and
Cd limits, using sludge analysis data.
Metal
Pb: Tons sludge/acre =
Zn: Tons sludge/acre -
Cu: Tons sludge/acre »
Ni: Tons sludge/acre •
Cd: Tons sludge/acre -
(Note: Sludge metals should be expressed on a dry-weight ppm
mg/kg basis).
The lowest value is chosen from the above five calculations as
the maximum tons of sludge per acre which can be applied.
Step 4. Calculate amount of P and K added in sludge.
Tons of sludge x % P in sludge x 20 = Ib. of P added
Tons of sludge x % K in sludge x 20 = Ib. of K added
Step 5. Calculate amount of P and K fertilizer needed.
(Ib. P recommended for crop)* - (Ib. P in sludge) = Ib. P fertilizer
needed
(1 Ib, K recommended for crop)* - (Ib. K in sludge) = Ib. K fertilize
needed
A sample calculation may be found in Appendix B.
*P and K recommendations based on soil tests for available P and K. Fertilizer
recommendations can be obtained from Cooperative Extension Service or soil analysis
laboratory.
Lee E. Sommers and Darrell W. Nelson are Associate Professor and Professor, re-
spectively, Agronomy Department, Purdue University, West Lafayette, IN 47907
3.7
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Section 4
CROP AND SYSTEM MANAGEMENT
for Sludge Application to Agricultural Land
Robert H. Miller
The primary emphasis of this document has been the application of sludge to
agricultural lands in a manner which will assure that no permanent damage is done
to the land or to the environment. This is particularly important if the land
receiving the wastes is leased rather than purchased and the farmer applies the
sludge to his land as an alternate source of nutrients. If this approach is followed,
the annual application rate will usually be based on nitrogen sufficiency for crop
growth (see Section 3) and usually will be under 10 tons/acre. The long-term quan-
tity of sludge applied to any one site will be based on the type and quantity of
metals present in the sludge (see Section 3).
This section contains a number of considerations important for managing the
farming operation when sludge is applied to land. As with so many other aspects of
waste application to land, no one proposal can be recommended for all situations.
The design and management of each site will be unique and require the coordinated
efforts of the farmer and/or farm manager, the treatment plant operator, and agri-
cultural engineers.
Management Considerations
Soil Management-Site Selection
Proper site selection prior to sludge application greatly simplifies soil man-
agement. These factors have been discussed previously in Section 2 and will be re-
peated only briefly before going on to other considerations.
Of primary importance to the success of the system is the establishment and
maintenance of a pH >6.5. Most metals are less soluble at pH 6.5 than at lower pH
values, and a pH >6.5 will restrict plant uptake and accumulation of metals as well
as their downward mobility in the soil. Soils should be selected which have the
desired pH or be limed until a pH of 6.5 or greater is attained. After sewage
sludges are applied, soil pH should be evaluated annually to insure that the pH
remains at or near pH 6.5. Oxidation of excess nitrogen to nitrate or sludge sulfur
to sulfate could lower the soil pH. Other soil properties influencing the chemistry
and availability of metals in soils include the cation exchange capacity (see Sec-
tion 3 and the influence of cation exchange capacity on maximum total sludge applica-
tion rate), the soil organic matter content, the presence of hydrous oxides of iron,
aluminum, and manganese, and the phosphorus content.
Soil drainage characteristics, which are influenced by a myriad of factors
(Section 2), are also important because they influence the timing and method of
sludge application, as well as tillage, planting, and harvesting operations after
sludge additions.
Soil Management-Fertility Considerations
The nitrogen in anaerobically digested sewage sludge usually consists of about
one-third ammonium. Other sewage sludges also contain significant concentrations of
ammonium nitrogen. The most commonly employed method of sludge application is on
4.1
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the soil surface, after which it may or may not be incorporated. If the sludge is
allowed to dry on the soil surface, considerable ammonia is volatilized into the
atmosphere. The actual amount lost will depend on the nature of the soil, soil water
content, quantity of sludge applied, and the sludge itself. It has been estimated
that 25-50% of the ammonium will be lost if sludge is applied on the surface. If
the sludge is injected directly into the soil or incorporated into the soil immmedi-
ately after surface application, most of the ammonium will be retained.
Sewage sludges generally contain considerably more phosphorus relative to the
nitrogen needs of most crops. Sludge applications based on the nitrogen requirements
of the crop may often over-fertilize with respect to phosphorus. Unless very high
amounts of sludge are applied, however, the soil will immobilize excess phosphorus
rapidly and over-fertilization should not present problems for many years. However,
in one experiment in Illinois, the application of a very high amount of sewage
sludge in a single year resulted in phosphorus toxicity to soybeans.
Sewage sludges are usually very low in potassium, a value of about 10 Ib. of
potassium per ton of dry sludge being common. Other cations in the sludge will often
compete with potassium in the soil solution and restrict potassium uptake by plants.
Thus, no credit should be given to even the low amount of potassium in sludges and
the soil should be fertilized with potassium according to the results and recommenda-
tions of soil tests.
Soil Management-Runoff Control
Sewage sludge applied to the surface of the soil without immediate incorpora-
tion can be transported in runoff waters and result in contaminated surface waters.
The potential danger of runoff increases greatly on sloping land in regions of high
rainfall and is the reason that soils to be used for sludge application should be
restricted to those with less than 6% slopes wherever possible. (See Section 2.)
The dangers are most severe if an intense rain occurs soon after liquid sludge is
spread on sloping land. Methods of application other than surface application must
be considered where sloping land is employed. Diversions or earthern barriers may
also be necessary to contain runoff temporarily, and prevent sludge from reaching
water courses. These latter considerations are all facets of engineering design.
Regardless of slope, certain conservation practices can be adopted which will
minimize runoff from sludge-treated soils. Such practices include reduced tillage
systems, terraces, strip cropping, and retention of crop residues on the soil surface
wherever possible.
Crop Selection
Crop selection is not an important management consideration in systems where
the sludge application rate is based on nutrient needs, or restricted to minimize
potential damage by heavy metals. The farmer or farm manager has available almost
all of the common agronomic crops.
With no limitations in the selection of plant species, it is usually advanta-
geous to maintain or utilize the normal cropping patterns found in the community.
These patterns have usually evolved because of favorable soil, climatic, or eco-
nomic reasons and will probably maintain certain advantages in the sludge applica-
tion system as well. One possible exception could occur if the cropping pattern of
the area is restricted largely to a single crop. Here there could be advantages in
employing an additional crop or crops to increase the opportunity of applying sludge
during a variety of seasons. A simple example would be a corn monoculture system
4.2
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vs. a corn and grass forage rotation. In the latter system, sludge can be applied
to corn land and incorporated prior to planting and after harvest. Additional sur-
face applications could be made on some soils of the North Central Region through-
out the winter months, subject to local or state regulations, when not frozen or
covered with ice or snow. The forage component would allow sludge applications to
land at those times when the corn land would be inaccessible, e.g., when too wet for
trafficability.
Timing of Operations
Timing of sludge applications to land as well as all the farming operations of
the system are dependent on climate, soil properties, the crop, and the tillage,
planting, and harvesting procedures employed.
Climate has a major influence on management of soils and crop systems receiving
sludge. Temperature has a direct influence on application of sludge in areas where
frozen soils or snow cover make sludge applications impractical or environmentally
unsound. In northern areas of the U.S., winter storage facilities for wastes are
required and increase the operation costs for the municipality. Temperature also
influences the growing season of plants and the rate of decomposition of sludge
organics in soil. Both of these factors influence the renovative capability of the
soil. The mean length of the freeze-free period in days (growing season) varies
greatly within the North Central Region from about 100 days along the Canadian border
to about 200 days in the southernmost states of the region. The freeze-free period
varies from 150 to 180 days in most of the Corn Belt. Useful temperature data for
the North Central Region can be found in N.C. Regional Publication No. 174 (9).
Rainfall has an influence on all management decisions involving sludge applica-
tion, tillage, planting, and harvesting. Care must be exercised to assure that
sludge is not applied to wet soils with heavy equipment. Such applications would
result in compaction and reduction in crop yields. Rainfall distribution also in-
fluences the amount of sludge storage required by a municipality. If the soils are
too wet for sludge application at the planned or desired time, the farmer may not
be able to accept the sludge as planned. Storage would thus be required until con-
ditions are again favorable for applications to continue.
Soil properties are extremely important to scheduling sludge application as
well as determining the ease and timeliness of all tillage, planting, and harvesting
operations. Applying sludge to land by almost all methods is an additional opera-
tion of concern to the farmer as well as the treatment plant. Delays for the farmer
may mean a disruption of his normal tillage and planting operations, and may be
economically unacceptable. Unfavorable soil properties, e.g., high water table,
saturated soils, etc., also mean that sludge cannot be applied in the Spring of the
year and reduce the acceptability of land application for a municipality which must
have the capability for all-season application. Likewise, delays in harvesting
because of wet soils might limit Fall application of sludge with the same result.
Thus it is very important that soils be chosen which are well enough drained to pro-
duce a minimum delay for all important operational procedures of the system.
The choice of crop or crops provides a means by which the farmer^as well as the
treatment plant operator can vary the time periods during which sludge can be applied
to land. These aspects have been discussed briefly under Crop Selection. Some flexi-
bility in sludge application can also be provided by altering the maturity dates of
small grains, corn, or sorghum cultivars so that harvesting, tillage, and planting
operations can more nearly fit the climatic or soil limitations on sludge applica-
tion discussed previously:,
4.3-
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Other Management Considerations^
There are some data showing that sludge can retard seed germination and early
plant growth. Most of these cases have occurred at sludge application rates higher
than those recommended here. The retardation is thought to be caused by a high con-
centration of soluble salts and/or high ammonia contents. These problems can be
further reduced by applying the sludge 2 to 3 weeks before planting, by thorough
mixing of the sludge in the tilled soil layer, or by a thorough irrigation prior to
planting. In the humid regions of the U.S., the problem will be potentially less
severe than in the more arid non-irrigated regions.
Herbicide applications for weed control on soils receiving sludge should be the
same as those normally used for a particular crop or soil. Weed control is espe-
cially important because of a desire to maximize crop yields and nutrient removal.
An additional weed problem may arise because tomato seeds survive waste treatment
and grow profusely in sludge-treated soils.
In general, the use of other pesticides on sludge-treated soils will not be
altered from the normal procedure recommended for untreated soils.
Sewage sludges should not usually be applied directly on leaves of growing
plants unless the sludge solids can be subsequently washed off by irrigation water.
Liquid sludge when applied on leaves of plants will dry and coat the leaves, reduc-
ing photosynthetic activity. Observations from studies in Illinois have indicated
that corn yields will be reduced if the leaves are coated with sludge repeatedly
during the growing season. If desired, liquid sludge can be applied to row crops
during the growing season by gravity irrigation techniques, by tank wagons, or by
overhead irrigation systems equipped with drop hoses between rows.
Sludges can be applied to forage crops during the season if applied prior to
spring growth, after dormancy, or immediately after cutting and before significant
new growth has begun.
Robert H. Miller is a Professor, Department of Agronomy, The Ohio State
university and Ohio Agricultural Research and Development Center, Columbus, Ohio
43210.
4.4
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Section 5
SELECTION OF THE SYSTEM
for Sludge Application on Agricultural Land
Richard K. White
System and equipment considerations are the major engineering inputs to a work-
able operation of renovating municipal sludges by land application. What are the
criteria which need to be considered in designing an acceptable system? The criteria
should meet the following: no detrimental impact on the environment (air, water, or
soil), while using the best available equipment to handle and apply the sludge on
the land, in an economical manner, with good management practices such as uniform
application and minimum nuisance.
Three phases in the handling of sludges for land disposal are interdependent:
treatment (storage), transport, and application. The degree of treatment will affect
the mode of transportation, e.g., vacuum filtered sludge will need to be hauled as
a solid. Partially stabilized sludge will need to be incorporated into the soil to
avoid nuisance. A vital part of the total handling system is storage to allow for
periods when application to the soil may not be possible, e.g., freezing weather or
soft ground.
Once the decision is made that the sludge will be handled as a slurry (liquid),
semi-solid, or solid (cake), the type of transportation and application equipment
can be selected. Table 5.1 indicates a range of solids content and handling charac-
teristics. In the following sections on Transport and Application, systems and equip-
ment will consider both liquid and semi-solid or solid sludges. One additional con-
sideration, without respect to the sludge being in the liquid, semi-solid, or solid
form, is whether soil incorporation is needed to prevent odor nuisance or surface
runoff.
Transport
The selection of the transportation systems and equipment should consider the
sludge production rate; i.e., quantity, distance to site, proximity of application
area to waterway, railway, or highway, whether application will be seasonal or year-
TABLE 5.1.—Sludge Solids Content and Handling Characteristics.
Solids
Type Content Handling Methods
Liquid 1-10% Gravity flow, pump,
tank transport
Semi-Solid 8-30% Conveyor, auger, truck
("wet" solids) transport (water-tight
box)
Solid 25-80% Conveyor, bucket, truck
("dry" solids) transport (box)
5.1
-------
round, and the life of the application area.
transport for both liquid and solid sludges.
Table 5.2 lists alternate modes of
For large cities, i.e., large quantities of sludge, the use of a pipeline,
barge, or rail tank car may be the best choice from an economical and management
viewpoint. The use of a truck which provides flexibility often is the best choice
for a smaller community. If hauling distances are long, it may be best to use tank
trucks for hauling over the highway and transfer to either a high flotation tank
truck or tank wagon for field spreading. If year-round application by truck or tank
wagon is selected, the use of flotation tires is necessary to allow field travel
over soft ground. The use of tank trucks provides flexibility in locating land
application areas, scheduling hauling, and enabling direct application, soil condi-
tions permitting.
TABLE 5.2.—Transport Modes for Sludges.
Type
Characteristics
LIQUID SLUDGE
Rail Tank Car
Pipeline
Vehicles
Tank Truck
Farm Tank Wagon
and Tractor
100 wet tons (24,000 gal.) capacity; sus-
pended solids will settle while in
transit.
Capacity determined by waterway; Chicago
has used 1,200 wet tons (290,000 gal.)
barges.
Need minimum velocity of 1 fps to keep
solids in suspension; friction decreases
as pipe diameter increases (to the fifth
power); buried pipeline suitable for
year-round use.
Capacity—up to maximum load allowed on
road. Can have gravity or pressurized
discharge. Field trafficability can be
improved by using flotation tires.
Capacity--800 to 3,000 gallons. Prin-
cipal use would be for field application.
SEMI-SOLID OR SOLID SLUDGE
Rail Hopper Car
Truck
Need special unloading site and equipment
for field application.
Commercial equipment available to unload
and spread on ground; need to level
sludge piles if dump truck is used.
5.2
-------
Commercial tank trucks are available from companies handling equipment for sew-
age and sludge handling and for livestock manure handling. Gravity discharge from
the tank truck is most common. The rate of discharge and the area of application
can be increased by using a pressurized tank or a pumped discharge.
Storage
At some point in the system for handling sludge, storage will need to be pro-
vided. It can occur at the treatment facility or at the land application site.
Except for large cities which may have limited space at the treatment facility, it
would normally be best to provide storage at the treatment facility. This storage
is necessary so that the transportation will not be hindered by fluctuations in the
sludge output. Storage is also necessary if a breakdown occurs in the transporta-
tion, or weather and soil conditions at the application area prevent immediate appli-
cation. Storage may be provided in the digester or aeration tanks for a short time.
For longer term storage, a tank or lagoon is normally used. Public acceptance of
storage tanks or lagoons at the treatment site is better than at the application
site.
Settling of suspended solids has been a problem in sludge storage units and in
tanks when hauling liquid sludge over long distances. The agitation of sludge in
storage units is necessary before transporting. It is best to minimize the number
of storage events in the handling system.
Application
The criteria for selection of application systems and equipment are dependent
upon several factors: the form of the sludge (liquid, semi-solid, or solid), the
quantity, the areal application rate, whether a yearly application to the same area
or one application in several years, whether seasonal or year-round application,
topography of the area, and time of year. To prevent runoff, some states may require
berms and/or diversions to be formed, requiring land shaping.
Two modes of application are surface or subsurface (soil incorporation). The
latter may be required to control odors of partially digested sludge. If large quan-
tities of digested sludge are being applied, soil incorporation may be necessary for
a good public image. Table 5.3 indicates methods and equipment which can be used
for surface or subsurface application of liquid and semi-solid sludges.
Surface application may be done by two general methods--irrigation or tank vehi-
cle. Experience has indicated that a fixed irrigation system, in lieu of using port-
able pipe, is easier to manage. Because of this, irrigation will be better suited
to a system which applies sludge regularly. It is possible to include sludge with a
treated wastewater irrigation application system. An irrigation engineer (agricul-
tural engineer) should be consulted to design the irrigation system.
Communities of 10,000 to 15,000 population have utilized tank trucks to apply
their sludge on farmland. The tank truck provides flexibility in when to haul and
where to apply the sludge. Year-round application can be performed by selecting
sodded fields for application during wet conditions. The use of a pumped discharge
on the tank (commercially available) will allow discharge over a wider area or from
a roadway, which may be important in an emergency.
If there is the possibility of public nuisance from sludge application, and for
greater nitrogen use efficiency, soil incorporation should be designed into the
application-systenw For.special conditions or at particular seasons of the year,
-------
TABLE 5.3.—Application Methods and Equipment for Liquid and Some Semi-sol id
Sludges.
Method
Characteristics
Topographical and
Seasonal Suitability
SURFACE APPLICATION
Irrigation
Spray (Sprinkler)
Ridge and furrow
Overland flow
Tank Truck
Farm Tank Wagon and
Tractor
Large orifice required
on nozzle; large power
and lower labor require-
ment; wide selection of
commercial equipment
available; sludge must
be flushed from pipes
when irrigation com-
pleted.
Land preparation needed;
lower power require-
ments than spray.
Used on sloping ground
with vegetation with no
runoff permitted; suit-
able for emergency
operation; difficult to
get uniform areal appli-
cation.
Capacity 500 to more
than 2,000 gallons;
larger volume trucks
will require flotation
tires; can use with
temporary irrigation
set-up; with pump dis-
charge can spray from
roadway onto field.
Capacity, 500 to 3,000
gallons; larger volume
will require flotation
tires; can use with
temporary irrigation
set-up; with pump dis-
charge can spray from
roadway onto field.
Can be used on sloping
land; can be used year-
round if the pipe is
drained in winter; not
suitable for application
to some crops during
growing season; odor
(aerosol) nuisance may
occur.
Between 0.5 and 1.5%
slope depending on
percent solids; can
be used between rows
of crops.
Can be applied from
ridge roads.
Tillable land; not usable
with row crops or on soft
ground.
Tillable land; not usable
with row crops or on soft
ground.
5.4
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TABLE 5.3.(continued)—Application Methods and Equipment for Liquid and Some
Semi-solid Sludges.
Method
Characteristics
Topographical and
Seasonal Suitability
SURFACE APPLICATION
Flexible irrigation hose
with plow furrow or_ disc
cover
Tank truck with plow
furrow cover
Farm tank wagon and
tractor
Plow furrow cover
Subsurface injection
Use with pipeline or
tank truck with pres-
sure discharge; hose
connected to manifold
discharge on plow or
disc.
500-gallon commercial
equipment available;
sludge discharged in
furrow ahead of plow
mounted on rear of
4-wheel-drive truck.
Sludge discharged into
furrow ahead of plow
mounted on tank trailer-
application of 170 to
225 wet tons/acre; or
sludge spread in narrow
band on ground surface
and immediately plowed
under—application of
50 to 125 wet tons/acre.
Sludge discharged into
channel opened by a
tillable tool mounted
on tank trailer; appli-
cation rate 25 to 50
wet tons/acre; vehicles
should not traverse
injected area for
several days.
Tillable land; not
usable on wet or frozen
ground.
Tillable land; not
usable on wet or
frozen ground.
Tillable land; not
usable on wet or frozen
ground
Tillable land; not
usable on wet or frozen
ground.
5.5
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TABLE 5.4—Methods and Equipment for Application of Semi-solid and Solid
Sludges.
Method Characteristics
Spreading Truck-mounted or tractor-powered box spreader
(commercially available); sludge spread evenly
on ground; application rate controlled by over-
the-ground speed; can be incorporated by disc-
ing or plowing.
Piles or windrows Normally hauled by dump truck; spreading and
leveling by bulldozer or grader needed to give
uniform application; 4 to 6-inch layer can be
incorporated by plowing.
Reslurry and handle Suitable for long hauls by rail transportation.
as in Table 5.3
soil incorporation can be omitted; e.g., cold weather or land areas located far from
residences. Soil incorporation will require a larger power unit to perform both till-
age and application simultaneously.
Where equipment is currently available at the waste treatment facility to de-
water the sludge into a cake, land application in a solid form may be the best option.
If the sludge has to be transported a long distance, economics may dictate dewatering.
Table 5.4 presents methods and equipment for applying sludge to the soil in the solid
form. The spreading method would generally be preferred over the piling or windrow-
ing so that normal farm tillage operations and cropping can follow.
It is important to consider the land application of sludges as part of the total
treatment system. This means that not only is the selection and use of suitable
equipment important, but also management of the total land application system once
it is operative. In fact, without good management the system will not function.
A review of the methods and equipment noted in this article will give a basis
for selection of land application system components as well as specific types of
equipment.
Richard K. White is Associate Professor, Department of Agricultural Engineering,
The Ohio State University and Ohio Agricultural Research and Development Center,
Columbus, Ohio 43210.
5.6
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Section 6
ANALYSES AND THEIR INTERPRETATION
for Wastewater Application on Agricultural Land
Boyd G. Ellis
Wastewaters may be generated by municipal, agricultural, or industrial waste
treatment facilities. Because of the nature of their origin, wastewaters are quite
variable and as such offer a great challenge to the analyst. Variation in data may
occur because of the method utilized in obtaining the sample or from laboratory to
laboratory due to the use of different procedures. Recommendations made here should
be considered as the procedure(s) that will produce the most uniformity in data and
not as the only method possible or even the best method in some cases.
Sample Collection
The most critical stage in analysis of wastewaters is generally in obtaining a
representative sample. Individual analyses require one liter (or qt.) or less
which represents a very small part of the total flow into or out of a waste treat-
ment facility. For this reason, it is recommended that the minimum be 10 equal vol-
ume grab samples obtained over a 2-day period and composited to give a single sample
for analyses. The ideal and common system involves automatic samplers which take
samples in proportion to flow for longer periods of time. More detail on sampling
is contained in North Central Regional Publication No. 230 (20).
Preservation of samples without some change in chemistry is almost impossible;
consequently, analyses should be completed as soon as possible after t"he sample is
obtained. To keep changes in the sample to a minimum during storage, the guidelines
by the U.S. Environmental Protection Agency (11) or American Public Health Associa-
tion (1) should be followed. It is important to note that a single method of pre-
serving samples is not adequate for all analyses.
Wastewater Analyses
Analyses which are recommended in all oases prior to application of wastewater
to land are given in Table 6.1. Other analyses should be made if the presence of
certain materials (i.e., heavy metals) is suspected in the particular wastewater.
Generally, a knowledge of the source of the wastewater is sufficient to identify
the analyses that should be made. Many of the procedures recommended are published
in Methods for Chemical Analysis of Water and Waste (11). Other alternative methods
are found in Guidelines for Planning and Conducting Water.Quality Experiments, a
joint report of NC-12 and NC-98 (19) and Sampling and Analysis of Soils, Plants,
Waste Waters and Sludges: Suggested Standardization and Methodology, a publication
of NC-118 (20).
As in all analyses, analytical procedures should be constantly checked in each
laboratory by the use of carefully prepared standards which match the matrices of
the samples being analyzed and by cross-checking with standard samples exchanged be-
tween laboratories.
Interpretation of Data
Any of the parameters listed in Table 6.1 may limit the quantity of wastewater
that may be applied to a particular site. In general, the parameters most likely
-6U-
-------
TABLE 6.1—Recommended Analyses and Procedures for Wastewaters to be Used in
Wastewater Application to Agricultural Land.
Parameter
Recommended
for Analysis
References
BOD5
COD
.% total solids
Conductivity
PH
Total N (nitrogen)
NOj-N (nitrate)
NC-2-N (nitrite)
NH*-N (ammonium)
Total P (phosphorus)
Soluble orthophosphate
CT (chloride)
K+ (potassium)
Ca2+ (calcium)
Mg2+ (magnesium)
Na+ (sodium)
Heavy metals
B (boron)
Pesticides
Industrial organics
Yes
Yes
If suspected to be high
If high soluble salts are suspected
Yes
Yes
Yes
Yes
Yes
Yes
If total P is high
If conductivity exceeds 250 ym/cm
at 25° C.
If conductivity exceeds 250 ym/cm
at 25° C.
If conductivity exceeds 250 ym/cm
at 25° C.
If conductivity exceeds 250 ym/cm
at 25° C.
If conductivity exceeds 250 ym/cm
at 25° C.
If source of wastewater includes
heavy metals
Municipal effluents and if suspected
in others
If suspected
If suspected
EPA (11)
EPA (11)
EPA (11)
EPA (11); USDA Hand-
book 60
EPA (11)
EPA (11); Black (4)
EPA (11)*
EPA (11)
EPA (11); Black (4)
EPA (11)
EPA (11)*
EPA (11); Black (4)
EPA (11)
EPA (11)
EPA (11)
EPA (11)
FWCPM"1" (1975)
EPA (22)
Electrode methods may be used if the quantity is greater than 10 ppm N as N0~
or 10 ppm Cl~.
fFederal Working Group on Pest Management. 1975. Guidelines on Analytical
Methodology for Pesticide Residue Monitoring, Pesticides Monitoring Journal. U.S.
Government Printing Office.
6.2
-------
to influence the short-term performance of a land application system are water, sus-
pended solids, readily decomposed organics (BOD5), nitrogen, and total salt. Para-
meters which may be critical in limiting the numbers of years a particular system
may be used include phosphorus, heavy metals, and industrial organics. A discussion
of individual parameters follows.
Water
Water is a natural resource which may be utilized for crop needs (i.e., applied
at low rates, less than 20 inches per year) or it may be renovated by its association
with the soil and the biological environment at considerably higher rates (i.e., 60
or more inches per year). The soil may pose definite limitations upon the quantity
of water which may be applied. (For a discussion of this aspect, see Sections 2 and
7.)
Suspended Solids and BOD
Suspended solids and BOD are generally low in secondary effluents but may"be
quite high in wastewaters from canneries or other industries which process agricul-
tural or forest products. Infiltration capacity can be lost by sedimentation and
slime formation if suspended solids and BOD loadings exceed the respiratory capacity
of microbial populations which decompose organics filtered out at or near the soil
surface. If the soil system is overloaded with BOD, anaerobic conditions will
develop, and severe odor and insect problems can result. At moderate rates of ap-
plication, the readily decomposed organics which give rise to BOD can augment the
vegetative cover in supplying energy for denitrification and structural carbon for
immobilizing nitrogen and other pollutants.
Nitrogen
Nitrogen in the nitrate form is the critical form of nitrogen because of its
solubility and mobility in water, its stability in groundwaters, and its implica-
tions for eutrophication and for human and animal health. The other mineral forms
of nitrogen are ammonium and nitrite. All three are readily taken up by plants.
Ammonium and nitrite are converted (nitrified) quickly to nitrate in moderately
well-aerated soil. Under poorly aerated conditions and in the presence of rapidly
decomposing organic matter, nitrate and nitrite are reduced (denitrified) to gaseous
forms which recycle back into the atmosphere. Both nitrification and denitrifica-
tion are biological processes carried out by microorganisms which are not very active
at temperatures below 50° F.
As much as one-third of the organic nitrogen applied in wastewater may be re-
leased (mineralized) as ammonium and nitrified to nitrate the first year. The re-
mainder will be retained (immobilized) in residual humus. The humus will continue
to decompose and release mineral forms of nitrogen and other nutrients in subsequent
years, but at very much reduced rates. The rates of initial and residual release
are reduced in the presence of rapidly decomposing carbonaceous materials (BOD)
which may be added as wastes or supplied by roots and surface trash from the vegeta-
tive cover.
In overland flow systems, nitrogen may not be a critical loading parameter
since the objective, frequently, will be to obtain partially renovated water for
intermediate use rather than for discharge. In low rate irrigation systems, inputs
of nitrogen should not exceed the capacity of the vegetation to take it up, plus
some allowance for denitrification and immobilization. If no crop is to be har-
6.3
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vested, some arbitrary limit--perhaps no more than 50 Ib. per acre per year--should
be set initially and adjusted as indicated by monitoring experience.
If crops are harvested, annual inputs of nitrogen should not exceed by more than
50% the anticipated harvest removal at yield goals which past experience indicates
can be attained on similar soils with good management (see Section 7). This quantity
is a function of both concentration and rate of application. An example calculation
is given below:
Problem: Wastewater with 12 ppm N as NH£ and 8 ppm N as N0~ is to be applied to a
corn crop with an expected yield of ISO bu./acre.
Question: How many acre inches of wastewater may be applied during the growing
season?
Calculation: 150 bu. of corn will remove approximately 125 Ib./acre of N; there-
fore, no more than 125 x 1.5 = 187.5 Ib. of N may be applied.
1 acre inch = 226,512 Ib. of water.
Therefore, -f2^i5^ . x 20 ppm N = 4.53 Ib. N/acre inch.
i } \f vv }
187.5 Ib. N
4.53 Ib. N/acre inch
=41.4 acre inches of wastewater maximum.
Little nitrate removal is expected during periods when actively growing vegeta-
tion is not present. Consequently, any level of nitrate exceeding 10 ppm nitrogen
would be considered a serious hazard in wastewaters applied to barren land. The use
of cover crops might well extend the successful application season on many treatment
sites.
High Rate
Nitrogen application rates for high rate infiltration percolation systems are
dependent upon the magnitude of denitrification and dilution within the aquifer.
These parameters uriH to highly site dependent and cannot be discussed in a gener-
alized manner.
Phosphorus
Phosphorus may be a key element for the success of a land treatment system when
viewed over the long term. It can be utilized by crops and adsorbed or precipitated
by the soil. Both total phosphorus and soluble orthophosphate determinations are
necessary for proper interpretation of data from wastewaters which are to be applied
to land. Within a few days (or weeks), all of the applied inorganic condensed
phosphates should be converted to soluble orthophosphate. Organic phosphorus may
be mineralized more slowly, but should be retained by the soil until converted to
orthophosphate. If the conversion to soluble orthophosphate occurs, wastewater may
be applied even without an actively growing crop with little danger of immediate
loss to the drainage water. The phosphorus will be adsorbed by the soil and a por-
tion of it will subsequently be removed by cropping. Soils from each particular
site should be examined with respect to their ability to adsorb phosphorus.
Due to limited contact between wastewater and soil in overland flow systems,
phosphate is inefficiently removed and runoff may not be of a quality that can be
directly discharged into surface waters.
6.4
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TABLE 6.2--Maximum Rates of Wastewater Application Related to Soil
Texture and the Ability of the Soil to Adsorb Phosphorus.*
Soil Textural Group Rate of Application
acre inches/year
Silty clay to clay 60
Clay loam 55
Loam 53
Sandy loam 40
Loamy sand 45
Sand 40
Assume 7 ppm total phosphorus in the wastewater and a crop removal
of 25 Ib. phosphorus/acre/year, with a 50-year expected life of the
system. Data from Michigan soils.
Soluble Salts
Soluble salts generally will not accumulate in the soils of the North Central
Region since precipitation surpluses in Fall, Winter, and Spring will remove salts
by leaching. This is not true in the arid or semi-arid areas of the United States.
In local situations, salts from special industries or from use on city streets may
give rise to abnormal concentrations in sewage or storm waters. Further concentra-
tion of salts occurs in soils by evapotranspiration. In soils which do not transmit
rainfall and irrigation water rapidly enough to keep salts moving downward through
the root zone, salt injury to sensitive crops can occur if wastewater containing
more than 1250 ppm dissolved solids (electrical conductivity about 2.0 mmhos/cm) is
applied regularly during the summer months.
Sodium Adsorption Ratio (SAR)
Sodium adsorption ratio (SAR) may be an important consideration in the use of
wastewaters even though Na (sodium), K (potassium), Ca (calcium) and Mg (magnesium)
are not frequently a problem in wastewaters. A calculation of SAR values should be
made according to the following equation:
Na
SAR = J Ca_+_McL
An example of this calculation for a typical wastewater is shown below:
Problem: A wastewater is found to have 150 ppm Na, 75 ppm Ca, and 20 ppm Mg.
6-.-5
-------
Question: What is the SAR for this effluent?
Calculation:
150 mg Na/1
23 mg/me Na
/
^/
"
75 mg Ca/1 + 20 mg Mg/1
20 mg/meCa 12 mg/me Mg
Wastewaters with SAR values greater than 15 should be avoided because of their
detrimental effect on soil structure and ultimate reduction in the infiltration rate
of the soils. Sodium adsorption ratio values from 5 to 15 can, over a period of years,
lead to loss of structure in soil horizons containing more than 10 or 20% clay (loam
or finer texture) . Lower values are generally satisfactory, although long term de-
clines in infiltration and percolation capacities have been observed in moderately
fine-textured soils when irrigated with water having SAR ratios as low as 3.
Afi cron u tri ents
Micronutrients and metals are expected to accumulate in the sludge and not in the
wastewater. Boron is a notable exception to this. It is likely to remain in the
wastewater and move with the soil water. The toxicity of boron is related to plant
species, with the most sensitive crops showing toxicity at 0.5 mg. B/l. Semi-tolerant
crops may show toxicity for levels of 1 mg. B/l. or greater. In some soil situations,
plants may actually benefit from low concentrations of boron in wastewater. The
same may be true for iron, manganese, and zinc.
Organic Compounds
Organic compounds are found in wastewaters. Pretreated wastewaters contain
natural products of partial decomposition and resistant synthetic compounds which
have detergent or chelating properties and can enhance the mobility of potentially
toxic trace organics and metals. Known organic toxicants which persist in waste-
waters from conventional sewage treatment include a number of pesticides, chlorin-
ated plasticizers, fire retardants, and other industrial chemicals. Most are strongly
adsorbed by soils and are subject to slow decomposition or alteration to harmless
products. They may pose an environmental hazard in special situations, particularly
if water is allowed to percolate too rapidly through the soil. Sources of such
chemicals should be identified and regulated to avoid excessive concentrations in
wastewater that is to be applied on land where discharge into streams or lakes might
occur.
Boyd G. Ellis is Professor of Soil Chemistry, Department of Crop and Soil
Sciences, Michigan State University, East Lansing, Mich. 48824.
6,6
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Section 7
CROP AND SYSTEM MANAGEMENT
for Wastewater Application to Agricultural Land
Arthur R. Wolcott and Ray L. Cook
Land application may be viewed as an alternative treatment method or as an
intermediate use for wastewater at a stage of renovation which cannot be discharged
directly into surface streams or lakes. The two views do not oppose but support
each other. The need to remove nitrogen and phosphorus from wastewater presents the
opportunity to use these and other waste nutrients to upgrade natural landscapes or
to support production of economic crops. In turn, beneficial responses of vegeta-
tion to added water or nutrients can contribute to the cost effectiveness of treat-
ment.
The choice of land application as a method for treating wastewater will be in-
fluenced by public policies and attitudes, funding incentives, and regulatory con-
straints which are described in other sections in this publication. Considerations
in site selection and system design also are dealt with in other sections. In this
section, factors which should be considered in selecting vegetative covers and
principles for management of wastewater application sites are discussed.
Selection of Vegetative Cover
The selection of vegetation to receive wastewaters cannot be considered inde-
pendently of the selection of site or design approach. Consideration must be given
to the hydraulic capabilities of soils and terrain in relation to natural hydrologic
systems or to hydrologic systems which can be imposed on the site by engineering.
Climate will influence decisions regarding site, design approach, and vegetative cover.
Economic or other advantages associated with a given type of vegetation or a given
resource management system must be considered as well.
Influence of Water Application Method
The widest latitude in choice of vegetative cover is afforded by low-rate irriga-
tion (2 to 8 ft. per year). Low-rate irrigation on moderately permeable soils and
slopes of 0 to 6% has the greatest potential for environmental benefit and economic
return of any design approach. Options for vegetative cover and resource management
systems range from public and private landscaping, greenbelts, wildlife habitats, or
commercial forest plantings to agricultural and horticultural crops. Perennial or
annual species can be considered, including intertilled crops.
In the case of crops grown for food or feed, the application of wastewaters
which originate in livestock operations or municipal sewage systems will be closely
regulated by state health authorities and marketing agencies. Restrictions on use
of wastewater will vary with the crop and from state to state.
For effective renovation by low-rate irrigation, the wastewater must enter and
percolate through 3 to 4 ft. of the soil profile. This approach may not be feasible
on slowly permeable soils which will not accept and transmit at least 2 ft. of water
per year. On such soils, substantially renovated water can be obtained by overland
flow.
7.1
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With suitable engineering, numerous crops can be grown in overland flow systems.
On grass or forest cover, as much as 20 ft. or more of wastewater can be applied
annually.
Vigorous, water-tolerant grasses which form dense sods are ideal for high rates
of application. Reed canary grass (Phalaris arundinaceae L.) and tall fescue
(Festuca elatior L., var. arundinaceae) appear most promising under climatic condi-
tions in the North Central Region. Reed canary is slow to establish itself from
seed. An established grass in old fields in many cutover areas is quackgrass (Agro-
pyron repens L.). Quackgrass rivals reed canary in production of tough, interlacing
rhizomes to bind the soil and carry heavy equipment.
All three of these grasses are highly productive under continuously moist con-
ditions. However, they lose palatability rapidly as they approach maturity and must
be cut two to four times a year to produce hay or silage acceptable to livestock.
A more palatable grass adapted to moist conditions is timothy (Phleum pratense
L.). This is a bunchgrass, not a sod former. Improved strains are highly produc-
tive and are readily established from seed. Timothy, seeded alone or with water-
tolerant legumes such as ladino clover (Trifolium repens L.) or birdsfoot trefoil
(Lotus corniculatus), can be used to provide productive ground cover quickly. Reed
canary drilled at the same time in widely spaced rows (3 to 4 ft.) will normally
spread, over a period of years, to dominate the stand.
In areas of the Western Region where humid conditions and diseases associated
with high humidity are not a problem, forage legumes such as alfalfa may provide pro-
ductive cover.
Influence of Wastewater Analysis
In most localities, municipal wastewater will be required to approach standards
for secondary treatment before it is applied on land. Standards for wastewaters
from wood products or food processing will be less strict, although primary treat-
ment may be necessary to remove grease or coarse solids which might clog distribution
lines or sprinklers.
Often the concentration of nitrogen left after these treatments will determine
the rate of wastewater application. The nature of the vegetative cover will be a
critical consideration, since the important processes which can remove nitrogen de-
pend on plant activities and plant products.
The fate of phosphorus is less dependent on vegetative effects. Nevertheless,
removal of phosphorus by plants will help to extend the useful life of soil minerals
which adsorb or precipitate phosphate. Other nutrients in wastewater are of concern
mainly in terms of the balance of nutrients needed for vigorous plant growth. In
special cases wastewater loadings may be limited by constituents which are toxic to
plants, livestock, or humans.
Nutrient Removal Capabilities
If wastewater is applied on vegetation which is not to be harvested, relatively
large acreages may be required to provide adequate renovative capacity. Under con-
tinuously moist conditions, accumulating masses of dead and dying vegetation can
intercept oxygen needed for normal root function. The excessive demand for oxygen
can lead to loss of infiltration capacity. Odors and insect problems also may be
aggravated. Grasses and other succulent vegetation should be clipped two or three
7,2
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TABLE 7.1.--Harvested Removal of Nutrients for Selected Crops and Yield Goals.*
Crop Yields and Nutrients Harvested. Lb./Acre
Nutrient
Yield
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Corn
Grain
150 bu.
125
22
28
3
10
Corn
Silage
25 T.
165
30
150
45
30
Wheat
Grain
60 bu.
72
13
14
2
4
Soybeans
35 bu.
120
12
36
5
6
Alfalfa-
Brome
5 T.
220
30
166
90
37
Reed Hardwood Forest7
Canary (Annual Uptake,
Grass* Lb./Acre)
5.5 T.
408
56
247
44
40
84
8
26
22
5
*Ellis, B. G. et al. (10)
Copper, W. E. (26)
times a season to stimulate new growth and avoid excessive accumulations of vegeta-
tive debris.
Nutrients which are not removed from the site by harvest of vegetation or plant
products will tend to accumulate in the system. Some nitrogen will be lost through
denitrification, perhaps 15 to 50% if inputs do not greatly exceed the nitrogen re-
quired for optimum plant growth. Nitrogen and phosphorus which are retained in a
standing crop, detritus, and residual humus must be reckoned with as potential sources
of soluble nitrate and phosphate at some time in the future.
The effective life of a system can be extended by removing some of the applied
nitrogen and phosphorus in harvested crops. Frequently the first consideration will
be to optimize harvest of nitrogen (Table 7.1).
In general, agricultural crops produce more harvestable dry matter with higher
nutrient content than tree species grown for "timber. Large harvest removals can be
achieved with perennial legumes and grasses if they are cut frequently at early
growth stages when their nutrient content is high. It should be recognized that
legumes can fix all of the nitrogen they need from the air, but they are active
scavengers for nitrate if it is present, as well as for phosphate.
The potential for harvesting nutrients with annual crops is generally less than
with perennials since annuals utilize only part of the available growing season for
growth and active uptake.
Design estimates of harvest removal should be based on yield goals which local
experience indicates can be achieved with good management on similar soils. Esti-
mates of nitrogen removal can be extended to allow for effects of roots and surface
trash left in the field after harvest. Unharvested residues retard the release of
soluble nitrogen during periods when no actively growing crop is present. They also
supply energy to support denitrification.
For design purposes, the overall capacity of a crop to remove nitrogen can be
estimated at 1-1/2 times the expected removal by harvest. If vegetation or plant
7.3
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products are not harvested, some arbitrarily lower figure will need to be used.
Actual removals will vary with many factors of site and management and can only be
determined by monitoring in the operational system.
Potential Toxicities
Normally, micronutrient imbalances or metal toxicities will not be a problem
with wastewater. In fact, low concentrations of boron, iron, manganese, or zinc may
be beneficial to plants on some soils. Increased uptake of cobalt, copper, molyb-
denum, or zinc into forage may benefit livestock.
Boron toxicity can occur in some situations since this element tends to remain
in solution through sedimentation, filtration, and biological treatment. If the
wastewater contains more than 0.5 ppm of boron, local agricultural authorities should
be consulted regarding tolerant crops which might be grown. If the concentration
exceeds 1.0 ppm, it may be necessary to identify and regulate sources of boron in
the waste collection system.
Unusual concentrations of organic toxicants (pesticides, industrial chemicals)
also will need to be regulated at their source.
Certain hazards are associated with ensiling or with indistriminate feeding of
forages maintained at excessively high levels of nitrogen nutrition. Abnormally high
concentrations of nitrate can build up in corn, sorghum, and succulent annual grasses
if growth is slowed suddenly by drouth, cold, or extended periods of cool, cloudy
weather. Nitrate poisoning can result if such roughages are used as the principal
ration for livestock. In the silo, nitrate can be reduced to nitrous oxide, a poi-
sonous gas which can pose a serious hazard to personnel for several weeks after silo
filling.
Grass tetany (magnesium deficiency) and fat necrosis (intestinal tumors) may be
encountered where cattle are pastured on grass receiving high rates of nitrogen.
Grass tetany is associated with high inputs of potassium relative to magnesium. Fat
necrosis has been found only on heavily manured fescue pastures.
Excessive nitrogen can cause lodging of cereal grains and reduce the process-
ing quality of crops such as sugar beets and potatoes. No toxicities are involved,
but such effects must be considered if these crops are to be grown and marketed
successfully.
Susceptibility to Disease or Insect Pests
A number of plant diseases and insects which attack plants are favored by moist
soils or by atmospheric humidity associated with frequent irrigation. The geographic
range and host plant specificity of these pests vary greatly. Frequently resistance
to a given pest can be enhanced by selective breeding. State and federal experiment
stations and other local authorities should be consulted to determine what pest prob-
lems might be anticipated and to identify plant species and varieties which are use-
fully resistant.
Climate, Soils, Topography
Native plant species or crops whose culture is well established in the general
area of the land application site are the most likely choices for vegetative cover
since their adaptation to local climate and soils is known. With adequate water and
nutrients on well-drained soils, any crop can be grown which is climatically adapted.
The availability of water will permit economically valuable species to be grown on
7.4
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FIG. 7.1.--Scrub oak and sparse native grasses on drouthy, cutover land in north-
ern Michigan, replaced (see Fig. 7.2) by corn irrigated with municipal wastewater.
Photo by R. L. Cook.
* . ' - .
FIG. 7.2.--Corn is a good candidate for irrigation with wastewater. Adapted hy-
brids with tolerance to important disease and insect pests are available for most
areas in the North Central Region. Photo by R. L. Cook.
7.5
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drouthy soils, so submarginal areas can be upgraded for more intensive uses (Figs.
7.1 and 7.2).
If it is necessary to apply wastewater frequently on slowly permeable soils, the
choice of cover may be narrowed to grasses or forest species. On rolling land sub-
ject to erosion, year-round protection should be provided through use of perennial
species or by fall-planted winter covers and trash mulch systems of management where
cultivated annual crops are grown.
Cropping Patterns
Operational efficiencies can be realized through specializing in the production
of a single crop for which there is a ready local market, or two or three crops which
require similar field equipment and handling facilities. Corn and sorghums are can-
didates for single cropping because available hybrids cover a wide range of climatic
adaptation and tolerance to disease and insect pests.
Monoculture promotes the build-up of specific diseases and insects. Many crops
cannot be grown in successive years in the same field for this reason. Rotation of
crops interrupts the normal life cycles of host-specific pests and helps to keep
their numbers low.
Rotation of crops offers benefits in addition to pest control. Rotations in-
volving cultivated and sod crops will help to maintain or improve soil structure and
the infiltration, aeration, and adsorptive capacities of the soil. On soils with
tight subsoils, improvements in internal drainage can often be achieved by growing
a deep-rooted legume like alfalfa or sweet clover from time to time. Irrigation may
need to be discontinued for a season to permit such crops to develop their character-
istically deep root systems.
Double cropping—soybeans or silage corn after winter wheat or barley, for
example—may be feasible where the growing season is long enough. The accessibility
of irrigation water helps to assure quick germination and rapid seedling development.
These are essential if two crops are to be harvested the same season. With suitable
short-season varieties and good management, the potential for harvest removal of
nutrients and for economic return is substantially greater than with more productive
long-season varieties which produce only one harvest a year. The system also pro-
vides year-round soil protection by vegetation and decomposing crop residues.
Other Considerations
Numerous other factors must be considered in selecting vegetative covers for
land application systems. Since large acreages may be involved, the established
agriculture of the area and available skills, equipment, storage, handling, trans-
port, and processing facilities are of prime importance, as well as the market
potential for crops which might be grown.
Regulations of state or local agencies may determine the quality of water or
the schedule of irrigations which can be used on crops for human or livestock con-
sumption. Availability of land or considerations of cost may dictate high irriga-
tion rates and the selection of water-tolerant crops or other vegetation, or these
same considerations may lead to selection of native vegetation on submarginal land
where wastewater can be applied at low rates or at sporadic intervals.
7.6
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Management of Wastewater Application Sites
Under provisions of the 1972 amendments to the Federal Water Pollution Control
Act, areas used for land application of wastes will be regulated as "non-point"
sources of pollution. For this reason, they must be managed as an integral part of
the total waste renovation system. The primary objective must be to produce reno-
vated water meeting federal and state standards for surface discharge, groundwater
recharge, or special intermediate uses. An important but secondary objective is to
realize economic or other benefits which can be credited against the cost of treatment.
Timing and Rate of Wastewater Application
Water suitable for groundwater recharge or for surface discharge of underdrain-
age can be obtained by low-rate irrigation. Application rates should not exceed the
soil's capacity to accept water without runoff or without ponding for more than an
hour or two. Instantaneous rates on intertilled crops should not exceed 0.5 inch
per hour on loamy sands or 0.1 inch per hour on clay loams. Somewhat higher inten-
sities may be feasible on grass or forest vegetation. To avoid excessively rapid
transit through the soil, the total application should not exceed 1.5 to 2 inches in
a 24-hour period--even on soils which will accept more water.
Weekly loadings and irrigation schedules should allow sufficient residence time
for waste constituents to interact with soil systems and plant roots. On permeable
soils, up to 4 inches of water per week (including rainfall) may be feasible during
summer and early fall when evapotranspiration is high. At other times, treatment-
effective loadings will be much less because of precipitation surpluses and reduced
biological activity. Wastewater containing high concentrations of nitrate should
not be applied on cold soils (below 50° F.) when vegetation is dormant and denitri
fication occurs slowly or not at all.
Winter irrigation of cultivated cropland should not be considered in the north-
ern tier of states in the North Central and Western Regions. On grass or forest
vegetation, winter irrigation with low nitrate water at reduced rates may be feasible,
except during very cold weather or when soils are frozen.
Irrigation schedules should allow for resting periods between applications for
drainage and aeration of the root zone. This is commonly achieved by irrigating
every 2 to 10 days. Longer intervals are required during cold weather than at nor-
mal growing season temperatures. Oxidizable organics (BOD) applied with wastewater
can build up in surface soil to the extent that infiltration and aeration are inter-
fered with and anaerobic conditions develop which are conducive to odors. This is
frequently the factor which determines how often processing wastes high in BOD can
be applied in low-rate irrigation systems. In cold weather it also can be a factor
with wastewater pretreated to reduce BOD.
Rapid infiltration is not essential for treatment of wastewater by overland
flow. Some deep percolation can occur, depending on slope and soil type. However,
the main flow of water is downslope--over the surface or by seepage through upper
soil layers. Suspended solids are filtered out on vegetation, litter, and soil.
Thus, they are distributed over a very large surface area exposed to the air. BOD
is dissipated rapidly, even at near-freezing temperatures. Effective residence times
can be achieved on uniform slopes of 0 to 6% with downslope exposures of 150 to 200
feet. Daily applications can be made, except during rainy weather. During cold
weather, applications may need to be less frequent or discontinued if soil and litter
are frozen.
7.7
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Nitrogen can be removed effectively by overland flow. At temperatures below
50° F., however, nitrate in the wastewater may pass through the system unaltered since
very little will be taken up by the vegetation or removed by denitrification. Much
of the ammonium and organic nitrogen filtered out from winter applications may be
released rapidly as nitrate when biological activity resumes in the spring. Phos-
phorus is removed less effectively than nitrogen. Runoff from overland flow may
not meet standards for discharge and may need to be diverted for low-rate irrigation
on other land areas or for permitted uses in industry.
In both overland flow and low-rate irrigation systems, water applications must
be discontinued well in advance of field operations so soils can drain and stabilize
to carry tillage or harvest equipment without serious impairment of soil structure.
Applications should not be made on bare soil except as needed to promote germination
and rapid development of a newly planted crop.
Tillage and Residue Management
Tillage operations which expose bare soil should be kept to a minimum. Conven-
tional plowing (8 to 10 inches) and preparation of a seedbed free of weeds and trash
are necessary for most vegetables and root crops. Many field crops, however, can be
planted directly in sod or trash from a previous crop or after partial incorporation
of residues by shallow discing. On some soils, it may be necessary at some time to
plow very deep (2 ft. or more) to mix impermeable subsoil strata with more permeable
surface materials. More often, impermeable pans formed by vehicular traffic or by
natural processes can be broken up by subsoiling equipment which leaves the surface
protected by vegetation or stubble and trash.
Minimum tillage and no-till methods conserve fuel, reduce labor costs, and mini-
mize compaction of soils by heavy equipment. Crop residues left on the surface or
partially incorporated to a depth of 3 or 4 inches provide protection against runoff
and erosion during intervals between crops. The decomposition of residues on or near
the soil surface helps to maintain a friable, open condition conducive to good aera-
tion and rapid infiltration of water.
Local soil conservation district personnel should be consulted regarding till-
age practices appropriate for specific crops, soils, and terrain.
Vegetative covers should be managed to promote both a high rate of nutrient
harvest and frequent return of unharvested residues. Return of residues is particu-
larly important where wastewaters have been treated to reduce BOD. The residues
serve to restore an effective balance of energy and structural carbon relative to
nutrients and toxicants. The cycling of nitrogen and phosphorus through decay organ-
isms and their products helps to regulate the release of soluble nitrate and phos-
phate. Actively decomposing organic matter also helps to reduce the concentration
of other soluble pollutants and can hasten the conversion of toxic organics, like
pesticides, to less toxic products. Carbonaceous solid wastes or wastewaters high
in BOD, from canneries or wood processing industries, can be used to augment pro-
duction of organic matter by on-site vegetation. Minimum tillage or no-till methods
will reduce decomposition rates and help to maintain or increase the level of cycling
organic matter in the soil.
Another approach for restoring the carbon balance in pretreated wastewaters is
to manage lagoons and holding ponds so as to promote growth of aquatic plants. These
can be harvested for feed or for application on land.
7^8
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Nutrient Imbalances, Toxicants, and pH Control
Wastewater applications in a given situation may be limited by one or a combina-
tion of several loading parameters: water, suspended solids, BOD, phosphorus, solu-
ble salts, sodium, or in special cases by certain micronutrients, metals, or toxic
trace organics. In any case, nitrogen loadings should not exceed 1-1/2 times the
anticipated removal of nitrogen by harvest except as justified by actual monitoring
experience on the site.
At this level of nitrogen input, many wastewaters will supply other essential
nutrients in quantities adequate for optimum production of crops. Nutrient imbal-
ances may occur, however. These must be corrected since vigorous growth and high
yields are essential to assure efficient removal of eutrophying nutrients by harvest
and maximum benefits from living vegetation and decomposing residues.
Nutrient imbalances can be identified by visual symptoms and quick tissue tests
in the field. Field diagnoses can be confirmed by detailed analysis of plant tissue
sampled at a critical stage of growth. Often, developing deficiencies or toxicities
can be detected, before serious imbalances occur, by testing soils systematically
every year or two for available nutrients and pH.
The balance among major and secondary nutrients is of primary concern. Analy-
tical determinations should be made for phosphorus, potassium, calcium, and magnesium,
using methods of known diagnostic value for soil or for tissue, as the case may be.
Total nitrogen (Kjeldahl N) can be useful, but the level of nitrate (NOg) in tissue
or soil is a more sensitive indicator of the nutritional status of plants with
respect to nitrogen. Nitrate also should be determined in forages or leafy vege-
tables if there is reason to suspect concentrations which might be toxic to livestock
or humans.
Imbalances involving micronutrients and other metals will be determined mainly
by soil pH rather than by their concentrations in the wastewater. Toxicities are
most likely under acid conditions and may develop simply because of the increased
availability of native soil sources. Deficiencies of essential micronutrients are
more likely under alkaline conditions. Molybdenum and selenium are exceptions, and
forage contents toxic to animals have been associated with soils above pH 7.0.
Problems of deficiency or toxicity will be minimized if surface soils are main-
tained at pH 6.5 to 7.0. This can be done by adding lime to acid soils or sources
of acidity (alum, sulfur, iron sulfate) to alkaline soils, as indicated by soil tests
made every 2 or 3 years. If the wastewater is very acid (pH 4.8 or lower) or very
alkaline CpH 8.3 or higher), these extremes will need to be neutralized before the
water is applied on living vegetation.
Supplemental nutrients to correct deficiencies can be applied through the irriga-
tion system or by suitable attachments to tillage or planting equipment. Supplemental
fertilization should be gauged to actual needs and regulated as indicated by visual
symptoms or by changes in soil or tissue tests.
Abnormal tissue analyses and visual symptoms can be caused by conditions, such
as high salt concentration or poor soil aeration, which impair root functions. Salt
concentrations in certain processing wastewaters may be high enough to cause direct
injury to plants unless salt tolerant species are grown. More often, injurious salt
concentrations build up during the growing season in soils which do not transmit
water fast enough to assure leaching. Wastewaters with unusual salt content (high
7.9
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electrical conductance) should not be used for low-rate irrigation on slowly per-
meable soils unless means can be found to improve internal drainage.
Loss of soil permeability may result from effects of waste constituents such as
clay or sodium. If sodium is responsible, it may be necessary to increase the cal-
cium content of the wastewater or to amend the soil with sources of calcium (gypsum,
slag, lime). Deep tillage or the installation of additional tile for underdrainage
may be needed to assure rapid movement of salts and sodium through the soil. Improve-
ments in internal drainage also will improve soil aeration.
Pest Control
Problems with weeds, insects, and plant diseases are aggravated under conditions
of frequent irrigation, particularly when a single crop is grown year after year or
when no-till practices are used. Most pests can be controlled by selecting resis-
tant or tolerant varieties and by using pesticides in combination with appropriate
cultural practices. State and local experts should be consulted in developing an
overall pest control program for a given situation.
Harvesting
Most crops require a period of dry weather before harvest to mature and reach a
moisture content compatible with harvesting equipment. Additional drying by artifi-
cial means may be necessary for safe storage or to meet market standards. Soil
moisture at harvest time should be low enough to minimize compaction by harvesting
equipment. For these reasons, irrigations must be discontinued well in advance of
harvest.
To minimize disruption of irrigation schedules, harvesting and any tillage or
planting operations which follow must be carried out expeditiously. Adequate power,
labor, and equipment must be provided for this, allowing for inevitable delays due
to weather (Fig. 7.3). Poorly drained areas in a field can lead to expensive delays
(Fig. 7.4). Operations in such areas should be avoided until adequate improvements
in drainage can be effected.
Personnel
A wide range of managerial and technical skills may be needed to coordinate
land application with the collection, pretreatment, and storage of wastewater in a
total waste treatment system. A central core of professional expertise in sanitation
and irrigation engineering as well as the agronomic sciences is essential for a well-
managed land application site. Analytical capabilities for the monitoring required
by state agencies must be provided within the organization or by contract with inde-
pendent laboratories. These, plus necessary administrative and clerical personnel,
technicians, and labor, may suffice if wastewater is applied on submarginal land with
minimum management.
If there is concern for upgrading land use or for realizing economic return from
application of wastewater, other competencies will be required. Specific skills will
depend upon the proposed use of the land—whether for wildlife, recreation, forestry,
or agriculture. Managers for such areas should have professional training or unique
interests and experience appropriate for the type of management required. Technical
and mechanical skills will vary with the nature of the resource. Semiskilled labor
may perform many tasks, but well-trained personnel are needed to train and supervise
them.
7.10
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t
-v
• * / *- *-^*J^*
FIG. 7.3.--Timeliness in field operations requires heavy equipment and personnel
skilled in its use and maintenance. Soils must be allowed to drain and stabilize
before such operations. Photo by R. L. Cook.
»
FIG. 7.4.--Poorly drained spots in a field will be unproductive and can cause
expensive delays. Additional tile are needed here. Deep tillage may be needed
to repair damage to soil structure. Photo by R. L. Cook.
7.11
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In some situations it may be feasible to distribute wastewater to independent
operators. Such arrangements should be contractual. Legal counsel should be sought
in drawing up agreements which are mutually advantageous and yet retain rights of
access for monitoring purposes and provide for courses of action in the event that
water quality standards for discharge or groundwater recharge are not met. Personnel
and organization must be provided to administer such contracts.
Key individuals should have responsibilities for liaison with regulatory agen-
cies and for informational and educational exchange within the organization and with
the general public.
Arthur R. Wolcott is Professor of Soil Biochemistry, Department of Crop and
Soil Sciences, Michigan State University, East Lansing, Mich. 48824.
Ray L. Cook is Professor Emeritus of Soil Science and Chairman (Retired),
Department of Soil Sciences, Michigan State University, East Lansing, Mich. 48824.
7.12
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Section 8
SELECTION OF THE SYSTEM
for Wastewater Application on Agricultural Land
Ernest H. Kidder
Three methods of wastewater application to land are considered. They are
sprinkler irrigation, surface irrigation, and overland flow. Infiltration-percola-
tion systems are not discussed.
In the Western states, including those in the western part of the North Central
Region, both surface and sprinkler irrigation methods may be used. In the Eastern
states, the amount of land leveling and the resulting damage to the soil profile
would in most instances eliminate surface irrigation. The injection of wastewater
into the soil by knifing does not appear to be practical because of the disturbance
to the crop and to the soil which would result from weekly applications, and because
of the high cost of operating the application equipment. A renovation and utiliza-
tion concept of wastewater application is emphasized.
Water Management Strategies
Certifiable waste treatment plans may include cycles of re-use for purposes
which do not require water of the quality specified for terminal discharge. Uses
which generate revenue will contribute directly to the cost effectiveness of a system.
Such uses are to be found in industry, agriculture, forestry, and aquaculture.
There are beneficial uses of partially renovated water which may produce little
or no revenue but which can influence the quality of life and, indirectly, the eco-
nomic and social goals of communities and regions. These include irrigation of
public and private landscaping, greenbelts, and wildlife habitats, and containment
and control of surface flows for recreational and aesthetic purposes. Land applica-
tion and surface containment of wastewaters can lead to increased recharge and stor-
age in local groundwaters, with increased efficiencies in water use. Increased re-
tention of water in local reservoirs (holding basins, cyclic re-use systems, soils,
groundwaters) can contribute significantly to moderation of seasonal and long-term
fluctuations in stream flows and lake levels.
An essential objective in total design must be to provide for containment, moni-
toring, and control of wastewater flows until water of the desired discharge quality
is achieved. Seasonal and cyclic fluctuations in wastewater and storm water flows
originating within the system, and in natural flows entering from outside, must be
anticipated in the initial design. Probable increases in volume or changes in
quality of flows requiring treatment must be allowed for initially, or anticipated
in contingency plans for expansion or for adoption of new treatment technologies,
as needed, over the projected life of the system.
Design and management options for application of wastewaters will vary with the
hydraulic capabilities of available soils and terrain and their relation to natural
and engineered hydrologic systems (Table 8.1).
The renovative capabilities of soils and vegetation are utilized most effec-
tively with low rate irrigation systems (Fig. 8.1). With appropriate management,
drainage water suitable for surface discharge or percolate suitable for groundwater
recharge can he obtained.. Economic benefits from increased efficiencies in produc-
-------
TABLE 8.1—Comparative Characteristics of Low-rate Irrigation, Overland Flow,
and Infiltration-Percolation Systems.*
Design Approach
Factor
Low-rate
Irrigation
Overland
Flow
Infiltration-
Percolation
Liquid loading rate
Annual application
Land needed per 1 mgd
Soils
Slopes
Removal of suspended
solids and BOD
Removal of nitrogen
Removal of phosphorus
Fate of wastewater
0.5 to 4 in./wk.f
2-8 ft./yr.
140 to 560 acres
plus buffer zones
Moderately permeable
loamy sands to clay
loams
Cultivated crops:
0-6%. Forages and
forest species:
0-15%
90 to 99%
80 to 100%
(may exceed 100%)
95% to 100%
(may exceed 100%)
Evapotranspi ration
and deep percolation
for groundwater
recharge, discharge
into surface waters,
or recovery and re-
use. Runoff con-
trolled
2 to 5.5 in./wk.
8 to 24 ft./yr.
46 to 140 acres
plus buffer zones
Slowly permeable
silt loams to
clays
2-6%
4 to 120 in./wk.
18 to 500 ft./yr.
2 to 62 acres
plus buffer zones
Rapidly permeable
sandy loams to
sands
Less than 2%
90 to 99%
70 to 90%
50 to 60%
Runoff maximized
for recovery and
re-use. Relatively
little evapotrans-
piration or deep
percolation.
90 to 99%
0 to 80%
70 to 95%
Deep percolation
maximized for
groundwater
recharge, recovery
and re-use. Runoff
not allowed.
Negligible evapo-
transpiration.
Adapted from R. E. Thomas and C. C. Harlin, Jr. (28) and C. E. Pound and
R. W. Crites (23). EPA-660/2-73/006a.
Irrigation at 4 in./wk. would be seasonal. An 8 ft./yr. application would
average 2-1/2 in./wk. over a 40-week irrigation period.
8.2
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IRRIGATION SYSTEM
EVAPORATION
SPRAY OR
SURFACE
APPLICATION
ROOT ZONE
SUBSOIL
'SLOPE
• VARIABLE
PERCOLATION
FIG. 8.1.—Diagrammatic representation of the low-rate irrigation system
for wastewater renovation.
tion or increased yields of crops will compensate for increased costs for trans-
mission and distribution of partially treated wastewater and the need to extend
managerial control over relatively large acreages. In most cases, municipal efflu-
ents to be applied through low-rate irrigation systems will be required to meet stand-
ards for secondary treatment with regard to BOD, suspended solids, fecal coliforms,
and pH.
The permeability of fine-textured loams and clays is too low to accept and trans-
mit significant quantities of water in excess of normal precipitation in the humid
areas (see Section 2). On such soils, substantially renovated water for re-use can
be obtained by controlled overland flow. Other descriptive terms for this approach
are "hillside irrigation" and "grass filtration." The filtering action of vegetation
and associated organisms at or near the soil surface can remove suspended solids
and organics as effectively as conventional primary plus secondary treatment.
Sprinkler Irrigation
Sprinkler irrigation involves spraying water out through the air. The water
normally infiltrates the soil at the point where it falls. During recent years, a
number of mechanical systems have been developed for use on large areas. These
systems generally work quite well and a minimum of labor input is needed for their
operation (Fig. 8.2).
SPRINKLER IRRIGATION
RAIN DROP
ACTION
FIG. 8.2.—Diagrammatic representation of a sprin-
kler irrigation system for applying wastewater to
land.
8.3
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TABLE 8.2.—Range of Infiltration Rates for
Various Soil Textures.
Soil Infiltration Rates
in./hr.
Coarse sand 0.50 to 1.00
Fine sand 0.30 to 0.80
Sandy loam 0.25 to 0.50
Silt loam 0.25 to 0.40
Clay loam 0.20 to 0.30
Clay 0.10 to 0.25
Sprinkler irrigation is used extensively for the application of wastewater.
Rotary sprinklers, which range in capacity from 0.5 to 1,200 gallons per minute, make
possible a wide range of application rates. The soil texture, structure, and vegeta-
tive cover largely dictate the maximum water intake rate. Approximate infiltration
rates based on soil texture are given in Table 8.2.
It must be pointed out that the infiltration and percolation rates are a func-
tion of time, cropping practice, quality of water, permeability of deeper soil lay-
ers, and antecedent moisture in addition to the soil texture. It is strongly recom-
mended that infiltration and percolation tests be made at intervals along a radius
line on the specific soil (for methodology, see Appendix A). Observations during
these tests will provide the initial estimate of the application rate.
Because the water from the rotating sprinkler is projected through the air,
there is concern about the drift of tiny droplets (aerosols). Hence, isolation from
public roads and private property must be prescribed when sprinkling wastewater.
Some testing is being carried out with sprayer type nozzles and other applicator
devices at crop level in an attempt to reduce droplet drift by directing the spray
downward, decreasing the opportunity for droplets to become airborne.
The type of equipment used to apply the wastewater will vary depending on the
land area involved, available labor, economic and climatic factors.
Solid set type systems have been used, consisting of permanent buried or quick
coupling portable pipe laterals using properly spaced rotary sprinklers. Several
mechanized systems also are available. The side roll lateral in which the pipe be-
comes the axle to turn the supporting wheels is suited to low-growing crops. It
requires about an hour's labor every few hours to roll the lateral to a new setting.
The central pivot system, as the name implies, uses a lateral line supported
by towers to rotate about a pivot point. Great flexibility is available both in
application rates and rotation speeds. The system is powered by water hydraulics,
oil hydraulics, electric motors, air pressure, or mechanical cable. A rotation
period of one revolution in 8 hours makes three rotations in 24 hours possible.
A third type of system is a giant or boom sprinkler pulled through the field
by a winch. This traveling unit is supplied by a drag, high pressure, flexible hose.
Both its speed of travel and application rate can be adjusted. .It takes about an
hour's time to reposition the applicator unit, drag hose, etc., after each trip
through a field. This unit is commonly used in 40-acre fields and irrigates about
8.4
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10 acres with each trip through the field. However, giant sprinklers project water
high into the air and result in aerosol drift for a greater distance than smaller
sprinklers.
Surface Irrigation
Surface irrigation includes all systems which allow water to flow over the soil
surface and continually infiltrate as it flows. The land must be rather flat with
no excessive slopes for this system to be feasible (Fig. 8.3).
Generally, some land shaping is necessary to level the surface to a sloping
plane for efficient irrigation. The depth of top soil present should be considered
in planning for land leveling. Surface irrigation has not been extensively studied
for use in renovation of wastewaters, but is likely to be used in cases where aerosol
effects limit sprinkler irrigation. The various surface irrigation systems are
described and evaluated regarding their potential use for land application.
In one system, a ditch or a pipe distribute the water to the high end of the
field where it is discharged onto the surface. If a ditch system is used, various
structures are required to assure that water in the supply ditch is at the proper
SURFACE IRRIGATION
COMPLETELY
FLOODED
fff^Tl U I H U U U f* 7T~
FLOODING
RIDGE AND FURROW
FIG. 8.3.--Diagrammatic representation of two surface irrigation
methods for applying wastewater to land.
8,5
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elevation. Pipe systems may be either buried pipes with risers which bring the
water to the surface or may be gated pipes placed on the surface of the soil. Where
surface irrigation is used, a ditch system is required for collecting and handling
excess water which runs off the lower end of the field. This runoff could be applied
to a lower field, pumped back to its original supply ditch and applied again to the
same or other fields, or returned to storage.
In another system, the entire surface of the soil may be inundated or small
channels may be formed to carry the flow over only a part of the surface. The par-
tial flooding systems are called furrow irrigation if a row crop is involved.
Smaller channels similar to furrows used for a cover crop are generally spaced closer
and are called corrugations. Ridge and furrow irrigation involves the use of large
channels with crops planted on ridges between furrows. These large furrows may be
flat, forming long narrow basins which are filled and allowed to set while water
infiltrates from them.
Any of the partial flooding systems should be applicable to wastewater irriga-
tion. When water contains some suspended solids, the surface of the furrows may
tend to seal after they have been wet for several hours, but a period of rest during
which the soil surface is allowed to dry should restore the infiltration rate.
Bendixen, et al. (3) report satisfactory operation of a ridge and furrow system in
which effluent from a two-stage trickling filter was applied to a silt loam soil.
In some cases occasional tillage of the furrow may be necessary to fully restore the
infiltration rate.
Land prepared for furrow irrigation also provides good surface drainage for
handling runoff from heavy precipitation. Furrow systems would be advantageous for
wastewater application because water does not contact the plant foliage and hence
wastewater residues are not deposited on the plant.
For surface irrigation where the entire surface is flooded, an earth structure
is required to guide the flow. For conventional border irrigation, small levees
guide the flow down the slope. Contour borders with dikes along the contours, or
contour ditches which distribute the flow across the slope and allow water to flow
from one ditch to the next one down the slope, also are used.
Border irrigation appears to be the surface irrigation system with the most
potential for use in wastewater renovation. It has been studied rather extensively
and rational design criteria have been developed. Border widths usually range from
30 to 60 feet and slopes down the border are between 0.1 and 1%. Length of runs
ranges from 300 to 1320 feet. Slope across the border must be nearly zero.
The border irrigation system can be adapted to most soil types and can be
designed to work well even on sandy soils by using higher application rates. This
type of irrigation is generally used for grain and forage crops. Furrows may be
formed in border strips to irrigate row crops.
The development of automatic control systems for surface irrigation has been
slow. They are not totally perfected, but several ideas show promise and have been
successful in limited field use. Automation of a surface irrigation system requires
control of gates or checks in the supply system to provide for delivery of water to
the proper field location, and sequencing the opening and closing of turnouts which
deliver the water from the supply to the field. The devices which have been developed
to control the flow of water in supply ditches are checks and drop gates which may
be timer-controlled or operated by remotely controlled hydraulic cylinders. By
8.6
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OVERLAND FLOW IRRIGATION
EVAPORATION
SPRAY APPLICA TION -
SLOPE 2-6%
GRASS AND VEGETATIVE UTTER
RUNOFF
COLLECTION
OVERLAND FLOW
FIG. 8.4.--Diagrammatic representation of the overland flow method of apply-
ing wastewater to land.
setting time clocks prior to the beginning of an irrigation, water can be advanced
from point to point along a ditch by removing checks at set time intervals.
Overland Flow Irrigation
Overland flow (Table 8.1, Fig. 8.4) has been used successfully for renovating
food processing wastewaters and is presently being studied for renovating municipal
wastewaters as well [Carlson et al. (6), Hoeppel et al. (17)] If feasibility can be
demonstrated, overland flow might be used to renovate wastewaters from communities
in areas with soils of low permeability. Land-formed smooth slopes and a length of
run compatible with the soil texture are necessary to assure even distribution,
effective detention times, and containment and recovery of runoff. In effect, over-
land flow irrigation is a form of surface irrigation known as border check. The
emphasis is on "cleaning up" the large volume of water which flows down the slope
to be collected at the base of the slope for other use (Table 8.1).
None of the points mentioned previously will allow for the complete design of
a wastewater application system. The final choice and design of a wastewater appli-
cation method involves the input of a competent engineer, soil scientist, crop scien-
tist, and economist, as well as consideration of the regulations of local, state,
and federal agencies.
Ernest H. Kidder is Professor of Agricultural Engineering, Department of
Agricultural Engineering, Michigan State University, East Lansing, Mich. 48824. The
assistance of Dr. T. L. Loudon in the preparation of this section is acknowledged.
The figures used in this section are reproduced with the permission of C. E.
Pound of Metcalf £ Eddy, Inc. They first appeared in Pound and Crites (23).
-------
Section 9
PUBLIC HEALTH AND NUISANCE CONSIDERATIONS
for Sludge and Wastewater Application to Agricultural Land
Thomas P. Wasbotten
Plans for any proposed sludge and/or wastewater application project should be
reviewed with the local unit of government where the project is located for com-
pliance with local ordinances. Local, county, or district health departments should
also be contacted to obtain pertinent information on health regulations. The state
water pollution control agency should be contacted and they should be able to pro-
vide direction on any requirements of other state agencies. Assistance can also be
provided by the U.S. Environmental Protection Agency, the U.S. Department of Agri-
culture, Cooperative Extension Service, and the Food and Drug Administration.
In evaluating overall environmental impacts of any land application of waste-
water effluent or sludge system, consideration must necessarily be given to potential
public health hazards and offensive odor nuisances. Effects that must be considered
include groundwater quality, aerosols, contact with the wastewater or sludge by the
public and employees operating the facilities, insects and rodents, isolation from
the public, stormwater runoff from the site, and contamination of the crops.
Odor Control
Since state and federal government regulatory agencies require that sufficient
level of preliminary treatment be provided for wastewater systems (usually the equiv-
alent of secondary treatment), odor nuisance conditions should not be experienced
in the actual application of wastewater to the land. Experience with industrial
wastewater where offensive odor nuisance conditions have existed generally shows the
cause to be the result of inadequate treatment prior to land application, often com-
pounded by excessive ponding on the irrigation site. A more likely location for the
correction of offensive odors is at the source of the putrescible wastewater consti-
tuents .
Sludge applications to the land pose a much more serious potential for offensive
odor nuisances if not properly managed. Odor problems can begin at the point of
initial sludge handling and the odor potential can extend for a significant period
of time after the actual application of sludges to the land. Since sludges produced
from wastewater treatment facilities vary greatly in liquid or solid consistency,
chemical composition including chemicals which may be added for sludge conditioning,
and type and degree of preliminary treatment (very important with respect to odor
generation), a case-by-case evaluation is usually necessary.
Plans for land application should include provisions for soil incorporation of
sludge prior to rewetting of the sludge by the next significant rainstorm. Liquid
sludge application methods employing subsurface injection and liquid manure spread-
ing followed by plowing and discing have been cited in the literature as being suc-
cessful. Other treatment and odor control methods for sludge have included heat
treatment followed by sludge dewatering, composting, chemical treatment with high
concentrations of lime and chlorine, and pressure filtration of sludge cake. The
application of well-digested drying bed sludge to land has been successful for many
years and is still probably the most economical and normally odor-free method for
smaller facilities.
9.1
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The often employed method of applying liquid digested sludge to farmland has
not always been an odor-free method, but has been tolerated at isolated locations
because of the lack of frequency, duration, and intensity of the odors generated from
the application area in small installations. Many of these operations are faced with
citizen complaints and litigation as the frequency of application increases due to
greater volumes of sludge generated at the wastewater treatment plant and with
adjacent land use changes (i.e., a new residential type house in the country; the
adjacent farmer stopping his livestock operation and growing crops, thus eliminating
the manure handling operation, etc.)- However, with proper sludge digester opera-
tion, sludge handling techniques, and land management at the application site, these
odor problems can be kept to a minimum. Better management procedures should be
planned for new sludge application systems rather than just duplicating so-called
"successful systems" in a neighboring community.
Pathogens
The most serious question raised in land application systems for wastewaters and
sludges from a public health aspect is the potential for the transmission of patho-
gens, including both bacteria and viruses. Transmission can potentially occur via
the groundwater, via man coming into physical contact with either the wastewater
or sludge, via the food chain or handling of the crop grown on the land, and via
aerosols. In general, control methods have consisted of multiple barrier restric-
tions imposed by health regulatory agencies, including such techniques as immuniza-
tion of employees of wastewater treatment systems, requirements for the disinfection
of wastewater, the degree of digestion of sludges required before application, and
isolation of wastewater and sludge handling facilities from the public.
Although the soil is generally agreed to be an excellent filter and inactivator
of bacteria and viruses, the literature cites a number of cases where both viruses
and bacteria have traveled significant distances through the soil mantle. Of compar-
able concern, from a public health standpoint,-is the protection of the groundwater
aquifer from contamination by other wastewater or sludge constituents including
nitrate nitrogen. Many states require that the minimum U.S. Public Health Service
drinking water standards not be exceeded for any existing wells in the vicinity of
the project. Others require no measurable degradation to water quality from existing
wells or from future wells as a result of the project.
Aerosols are microscopic droplets which could conceivably be inhaled into the
throat and lungs. Aerosol travel and pathogen survival are dependent on factors such
as wind, temperature, humidity, vegetative screens, distance, etc. Little is actually
known about the survival of pathogens in aerosols, but research projects are underway
to evaluate this potential hazard. Current methods employed to reduce this potential
problem include isolation distances, vegetative screening, effluent and sludge appli-
cation techniques reducing aerosolation, i.e., low pressure, large droplet spray irri-
gation equipment, stopping of spraying during high winds, and disinfection prior to
application.
Parasites
The ova of intestinal parasitic worms are excreted in the feces of infected
individuals and are regularly present in raw sewage. Of particular concern have
been ova of Ascaris lumbricoides. These ova are generally resistant to adverse
environmental conditions and are still present in both treated wastewaters and sew-
age sludges. Concern with food chain transfer by the sludge-miIk-human route has
prompted at least one State Health Department (Ohio) to restrict sludge application
to dairy pastures. This is an area requiring an immediate, intensive research effort.
9.-2
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Insects and Rodents
The control of insects and rodents on a land application site is more critical
than for either other agricultural land or irrigated agricultural land because of the
possible transmission of bacteria and viruses from the wastewater or sludges. Wetter
conditions and increased vegetative cover also increase the potential for the number
of insects and rodents; however, conventional methods of control can normally be
utilized to control these pests. Mosquito propagation could be severe on wastewater
application sites unless the facility is properly designed and managed to eliminate
ponded water and allow for sufficient drying periods between applications of waste-
water.
Isolation from the Public
A number of constraints may be placed on wastewater and sludge land application
sites by local, state, or federal regulatory agencies that have current authority to
isolate the site from the public and from potential odor nuisance and health hazards.
Sites utilized exclusively for wastewater or sludge management systems must often
be suitably fenced and posted to inform the general public of the use of the site.
Isolation distances should be provided proportional to the degree of potential
health risk of aerosols from wastewater irrigation sites and risk of odor nuisance
from sludge application sites. Minimum distances may be imposed from residences,
water supplies, surface waters, roads, parks, playgrounds, etc. Public access should
only be on a regulated basis with due consideration given to the additional health
hazards associated with wastewater or sludge.
Stormwater Runoff from the Site
Along with the need to protect surface water quality, surface runoff from waste-
water and sludge application sites must be managed to protect adjacent landowners.
Commonly, berms and dikes are used to eliminate surface runoff from wastewater irri-
gation sites. Grass filtration wastewater irrigation systems should have collection
systems with additional treatment and disinfection to assure the resultant discharge
to surface water meets discharge requirements. Surface runoff from sludge applica-
tion sites can usually be controlled by conventional agricultural soil erosion con-
trol methods. With high rates of liquid sludge application, additional precautions
may be necessary to control surface runoff to reduce potential health hazards and
nuisance problems.
Contamination of the Crops
Almost all states either prohibit or tightly regulate the growth of crops direct-
ly consumed by man where sludges or wastewater effluent are applied. Of recent con-
cern are the largely unknown health effects of heavy metals, PCB's, mercury, and
other potential toxicants which may enter the food chain. Common practices to reduce
this potential involve control or elimination of the discharge of these toxic chemi-
cals at the industrial wastewater source. A prohibition of application of these
wastewaters and sludges to the land where agricultural crops or livestock operations
would cause a potential food chain problem could be applied by governmental regulatory
agencies.
Thomas P. Wasbotten is a Sanitary Engineer^ Municipal Wastewater Division,
Michigan Department of Natural Resources, Mason Building, Lansing, Mich. 48926
9,3
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Section 10
PUBLIC ACCEPTABILITY AND LEGAL CONSIDERATIONS
for Sludge and Wastewater Application on Agricultural Land
Terry F. Glover
Renovation of municipal wastewater and sludges on land is not particularly a
new concept, but it has undergone a recent revival because of water quality and
economic concerns. Such systems of renovation, if properly implemented, can greatly
reduce nutrient build-up in water courses and place the nutrients on land where they
can be used beneficially. Applying wastewater and sludge to the land is often a
more cost-effective waste treatment alternative than conventional renovative and dis-
posal techniques. However, municipal authorities and the public must recognize that
certain problems may arise when they consider the land renovation alternative. Among
these problems are concerns and procedures for acquiring the needed land for such a
system and the general acceptance by the public of the land treatment concept,
Legal and Economic Arrangements
Land Arrangements
Land treatment of municipal wastewater and sludges is an alternative that should
be evaluated after considering specific community conditions and goals. Once a deci-
sion is made to employ land treatment, a variety of land acquisition options can be
used. Each will have different impacts on landholders and the goals of municipal
authorities. The variety of the options used reflects varying capacities of commu-
nities to impose costs on landowners.
Fee simple acquisition of land (outright purchase) provides better control of
the renovation system by municipalities. It enables the municipality to pursue its
own goals within state, federal, and local law. However, the municipality is gener-
ally required to pay high land costs for the fee interest property rights and, in
addition, is required to add another function (agricultural production and management)
to its existing service activities. Land purchase is also more disruptive to farmers
and local agricultural economics relative to other types of land acquisition arrange-
ments.
In the North Central Region, municipalities will currently have to pay in the
range of $650 to $1,800 per acre for agricultural land which is suitable for renova-
tion of wastewater and sewage sludges. To purchase a farm unit and relocate the
family under condemnation procedures would currently cost in the range of $18,000 to
$26,000 for the farm headquarters buildings, plus approximately $8,000 in relocation
costs in addition to the land costs. This assumes the average tract of land to be a
160-acre unit.
Easements or use rights (other than fee interest) on suitable land can be
obtained without acquiring full property rights if mutual gains for the municipality
and farmer(s) exist. Such use rights could run the gamut of permanent easement to
seasonal land use agreements. Use-right arrangements reduce the control of the treat-
ment system by municipalities but lower the land cost and are less disruptive to the
local economy.
Acquiring the use of land via use-right arrangements usually meets with better
public acceptance than land acquired by fee simple acquisition. Further improvements
10.1
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in acceptability occur if all risks and unknowns of the renovation system are mini-
mized, fertilizer nutrients to farmers a.re made available economically with no incon-
veniences, and farmers' costs are reduced as a result of the arrangement.
One example of an inconvenience and unknown is excess water. Excess water is a
problem in most of the North Central states. Thus, application of wastewater to
land will be met with skepticism by farmers since they require nutrients as inputs
to their production activities but do not require greater water use. Excess water
imposes drainage costs in addition to the costs of irrigation. Such costs will have
to be borne by the municipality before they can negotiate for use rights to apply
wastewater to land (7, 16). In contrast, the water may be a distinct asset which
will attract use-right arrangements in more arid states of the United States.
Negotiations between municipal authorities and farmers to apply municipal
sludges to land will not meet with these problems since the quantity of water applied
with sludges is insignificant. However, farmers who apply sludges must be assured
that their soils or crops will not be temporarily or permanently damaged by factors
such as excess heavy metals or soluble salts.
Payments to the farmers or landowners for any use-right arrangement will cer-
tainly be involved if uncertainties with respect to the application of wastewater
and sludge to the land exist; e.g., unknown heavy metals, harmful salts, unknown
irrigation rates, etc. These payments by the municipality to farmers will probably
amount to approximately the existing net agricultural land rents in the area since
farmers stand to lose at least that much money if problems arise. For corn-soybean
land in the Corn Belt, such rents currently run in the range of $35 to $60 per acre.
If drainage is required, current tile and drain structure costs range from $200 to
$550 per acre, depending on local soil and topographic conditions. This figure
assumes 10% of the total drainage structure is already in place.
Land may also be acquired for use from wastewater or sludge farming cooperatives.
In such case, an agreement is made between the municipality and a group of landholders
organized into a cooperative for the purpose of receiving and using given amounts of
wastewater or sludge generated by the municipality. The application rate and timing
of wastewater or sludge applications to the land is largely determined by the members
of the cooperative. Some studies in Michigan and Ohio suggest that even under this
arrangement, most additional irrigation and drainage costs would have to be borne by
the municipality in the form of a payment to the cooperative. Negotiations often
break down if farmers' inputs are altered greatly because of additional capital for
modified drainage or irrigation systems.
Investment costs of sludge application equipment may be spread among farmers in
a cooperative arrangement. Operating costs may be included in the cost of sludge
delivered to the individual farm unit. Data for sludge analysis (nutrients and other
elements) would have to be provided to members of the cooperative before agreements
for land use and sludge delivery could be negotiated to insure a potential positive
economic return with minimal problems.
Governmental Agencies and Regulation
Recently special provisions in federal legislation under Public Law 92-500
(Water Pollution Control Act Amendments of 1972) have made land treatment of waste-
water a significant alternative which municipalities should consider because of reno-
vation capabilities and cost effectiveness. The law is a combination of coercive
legislation and incentive funding to achieve the objective of eliminating the dis-
charge of pollutants into navigable waters by 1985. The law also calls for public
10.2
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owned treatment plants to upgrade to at least secondary treatment processes by mid-
1977. The U.S. Environmental Protection Agency is the federal agency charged with
the responsibility of executing the law and allocating matching grant funds to the
states enabled by the law and appropriated by the U. S. Congress.
Grants to state and local agencies now encourage renovation of wastewater and
sludges on land as provided under subsection 20(d) of the 1972 Amendments. Encourage-
ment of wastewater treatment management that results in the construction of revenue
producing systems and recycling of wastewater and sludges through agricultural produc-
tion processes which are not harmful to the environment is now part of the grant pro-
visions of the Act (15). The grant program is designed to assist municipalities with
75% federal grant funds, leaving 25% as the local share of investment.
Acquisition of land sites which are an integral part of the treatment system
{excluding land used for sanitation buildings and treatment plants) is authorized
by other sections of the Amendments and is included in cost sharing. Federally
funded grants are available for all secondary and tertiary treatment systems provid-
ing such systems are the most practical from an operational viewpoint and subject to
demonstrations that such systems are most cost effective as outlined by section
212(2)(c) of the 1972 Amendments (12).
Municipal officials have to be aware of state agencies and regulations as well
as federal provisions. Indeed, it is the state agency with which municipal officials
will work most directly to initiate and implement land treatment systems. Generally
a specific water quality, pollution control, or intergovernmental relations division
of these agencies is set up to work directly with community officials on matters per-
taining to wastewater treatment.
Traditionally state agencies maintain control of water resources which are not
under the navigable waters control powers belonging to federal jurisdiction. How-
ever, very few states in the North Central Region have specific statutes and .regula-
tions pertaining to the application of wastewater and sludge on land, although this
status is changing rapidly. Some states have informal guidelines for wastewater
treatment in general, while others approve of various systems in compliance with
the federal regulations as reviewed by the state agencies. Currently, it is the best
practicable criterion (operational practicality and most cost-effective) interpreta-
tion of subsections 201(d) and 212(2)(c) of Public Law 92-500 which have moved
municipalities and state agencies to consider the land treatment alternative.
Other legal restraints with which municipalities should be familiar are regula-
tions restricting the use of condemnation powers, acquiring easements, and contrac-
tual agreements. Municipalities must have the authority or work in cooperation with
the appropriate governmental agency to acquire interest in land outside their juris-
dictions. Such authority or interest is usually restricted by state law. Authority
may be changed if a municipality is included in a sanitary district; i.e., extra com-
munity powers are enjoyed by such authorities. This is the case in Illinois, Michigan,
Ohio, and Wisconsin.
Public Acceptability
Acceptance or rejection of the land treatment concept by a particular community
and/or extra-community involved is based primarily on two elements of concern:
economy and health. Economic concerns are based upon the perception by landholders
or their neighbors of outside factors which might result in positive or negative
economic effects when wastewater and sludges are renovated within their community.
10.3
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Such outside factors may include loss of property values, loss of community tax base,
fear of odors, and others.
Health concerns are basic to everyone and can arouse even those individuals who
are otherwise indifferent to normal community affairs. It is easy for even small
groups of opponents to cause public controversy by raising doubts, founded or un-
founded, about the operation of a land treatment system and its impact on human
health. Such doubts are often resolved in favor of existing or conventional treat-
ment systems which are sometimes much more expensive and sometimes provide even less
protection of health. Negotiations within a community will surely break down if
current agricultural production systems are greatly altered at a higher cost and in-
formation about potential health problems remains vague.
Important Factors Influencing Public Acceptability
A number of factors are of particular importance in destroying the opportunity
for favorable public acceptance of a land treatment system.
• Implementing a land treatment project without presenting the known facts to
everyone concerned about the operation of the system (economics, health, or risk of
nuisances) is inviting failure. It should also be noted that providing such informa-
tion will not insure acceptability. However, previous social research and experiences
in the water resource development area suggest that perception of the rationale for
the proposed project is an important factor in determining the reaction of indivi-
duals to both the project and municipal officials and agencies involved.
• The magnitude of community resistance varies directly with the magnitude of
economic disruption and population relocation. This suggests that land acquisition
by outright purchase should seek very large tracts from a minimal number of rural
landholders. However, this works against minimizing economic disruption because such
an action imposes serious income redistribution in rural areas between landholders
and others receiving income from rural enterprises.
• Localized neighborhood resistance at the site other than from the landowners
will most generally exist either for economic or health reasons. Such attitudes will
often generate widespread public controversy and must be counteracted by accurate
information and community education.
• Renovation of a municipality's wastewater and/or sludge involving land in
another political jurisdiction may present additional problems. First, voter indif-
ference in these jurisdictions may delay the decision-making process. Second, the
concerns with economic health or nuisance problems may be magnified in these juris-
dictions and result in outright rejection of the idea of land treatment.
• If farming practices are to be changed greatly and/or profits reduced by
applying wastewater or sludges to land, there will often be no basis for mutual nego-
tiations between farmers and municipal officials. In the Corn Belt, for example, a
change from an intensive corn-soybean enterprise to a grassland-beef enterprise would
mean reduced profits under current economic conditions and would not be acceptable.
However, some farmers may choose to cease intensive production activities and find
that engaging solely in the supply of use rights to municipalities is a profitable
and desirable alternative.
• Generally large land application projects are more likely to fail because
they are more difficult to control physically or economically.
10.4
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• Excess water is a problem in all but the Western North Central states and
limits farmer acceptability of the quantities of wastewater deemed economical and
necessary by the municipality. These differences in opinion should be reconciled
before plans are made.
Initial Approaches to Obtain Acceptability
The concerns and restraints mentioned above make it imperative that municipali-
ties purposely plan steps to gain public acceptability in the initial stages of devel-
opment of a land treatment system. A number of important steps are discussed below.
It is important to inform farmers, their representatives, other governmental
agencies, the press, and homeowners about the known effects of land treatment, both
beneficial and detrimental, including legal information about land acquisition.
• Municipalities must work out the details of legal restraints within which
land treatment can be operative.
• Municipalities should avoid the negative reactions associated with premature
announcements that large acreages are proposed to be used for treatment prior to
announcements about the sewage problem and the land treatment alternatives. Farmers
and other groups should be informed about the operation of the system and its land
requirement given the sewage load of the municipality.
• If the decision has been made to purchase the necessary land, do not sched-
ule to purchase or obtain use-right arrangements immediately. Rather, a schedule
of land acquisition should be set up over 2 to 5 years. A contract arrangement with
one or two farmers in the initial year could be made (or a farm unit purchased) and
the unit could be set up as a demonstration and monitoring site for public view and
to work on minimizing the uncertainities before pushing ahead with larger acreages'.
• Municipalities should consider operation of land treatment systems with a
wide variety of land acquisition arrangements, ranging from purchase of tracts
offered for sale over time, use-right arrangements with a fee, use of land other
than agriculture to direct opposite negotiations; i.e., bid by farmers to acquire
wastewater and sludge on their farms. The systems should be flexible with respect
to wastewater and sludge application rates and terms of contract, which might re-
quire planning for increased storage at the treatment plant or at some station point
near land sites. Operation agreements should also be flexible in order to stimulate
new technology with lower costs of operation.
• The municipality should be certain that net costs not be transferred from
the sewage generating region to the recipient region. If this occurs, a form of
compensation will have to be paid in addition to the use-right fee.
• Different community decision-making units may have to either be brought to-
gether (county, municipality, and farmers) or re-arranged so that representatives
of the agricultural sector, homeowners, county and municipal officials all have
participation in the decisions involving land treatment. This is a form of inter-
nalizing the public acceptance problem. In such cases each voter has some stake in
the decision and bargaining positions can be expressed and made known to municipal
officials.
• Land purchase or the "city farm" arrangement is often desirable for a munici-
pality because it allows better control of the system. However, the arrangement is
often viewed negatively by the public and results in land being taken from the tax
10.5
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Tolls, Use-right arrangements, or better still, bidding by fanners to receive the
nutrients are better arrangements for public acceptability, but result in weakened
municipal control and contract terms.
Continual conversion of uncertainties of the system into known facts aids
decision making, lowers costs, and increases acceptability. Acceptability is also
enhanced if knowledge of this conversion is widespread among various groups who must
interact on public service delivery decisions, including farmers and others inter-
ested; in the rural scene.
Terry F. Glover is Associate Professor, Department of Economics, Utah State
University, Logan, Utah 83422.
10.6
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Section 11
SITE MONITORING CONSIDERATIONS
for Sludge and Wastewater Application to Agricultural Land
Paul A. Blakeslee
Monitoring in the broad context includes observation of system performance,
checking the quality of affected natural systems, and observing and recording envi-
ronmental impacts as quality changes occur. The role of monitoring in land applica-
tion systems should be that of confirming the predictions and judgements made during
the project development and design stage with respect to these systems. It should
be employed as a tool in expanding understanding of system performance, not as a
substitute for the fullest reasonable understanding of the many interrelated physical,
chemical, and hydrologic factors within any project prior to implementation.
The project designer must consider the impact of three basic factors on the
natural system when developing a wastewater or sludge application proposal in order
to predict project success. The factors for prime consideration are:
• Public health impact through disease transmission
• Toxic materials and their impact
Nitrogen compounds and their impact on ground and surface water sources.
The objectives of system monitoring can be fulfilled by developing a monitoring
program which considers:
• Applied wastewater and/or sludge characteristics
Soil characteristics
• Groundwater and surface water quality
Quality of vegetation produced.
The costs of an effective monitoring program should be incorporated into the
routine and ongoing costs of operation of the unit generating the wastewater or
sludge to be treated or used in an on-land application program. It may be possible
to develop a full monitoring program including all sampling and testing capability
within the normal operations of the generating unit where a large scale operation
is involved. For smaller projects, the specialized testing methods to be employed
may require the use of Cooperative Extension Service and/or commercial testing
services.
Wastewater and/or Sludge Characteristics
The wastewater or sludge to be applied at a site is like the raw material in a
manufacturing process. To be assured of an acceptable end product, i.&., crop, en-
riched soil, or other benefit to the system,, the raw material must be of consistent,
known, and acceptable quality. The recommended analyses have been covered in Sec-
tions 3 and 6.
11.1
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Soil Characteristics
The characteristics of the soil system employed for treatment should have been
fully established during project design and the monitoring program developed should
identify changes in these characteristics to avoid permanent or irreversible soil
system damage. Samples of the untreated soil should be collected and retained for
future testing. The concentration of applied trace elements in the soil and where
possible the available chemical form of such materials should be routinely determined.
The frequency of such determinations may vary from project to project, with the
monitoring frequency being adjusted to the rate of change observed and project scope.
In cases where domestic wastewater or sludge with little industrial waste present is
applied, annual sampling may be sufficient.
Common groupings of elements which should be considered for soil monitoring
can be determined from the composition of the waste material. These may include:
Cadmium, chromium, copper, lead, nickel, and zinc
• Mercury, arsenic, chromium, and boron.
If other potentially harmful metals or organics are present in the wastewater
or sludge, the testing program should be expanded to include them.
Groundwater Monitoring
Monitoring wells must be designed and located to meet the specific geologic and
hydrologic conditions at each site. Consideration must be given to the following:
• Geological soil and rock formations existing at the specific site
Depth to an impervious layer
Direction of flow of groundwater and anticipated rate of movement
• Depth of seasonal high water table and an indication of seasonal varia-
tions in groundwater depth and direction of movement
• Nature, extent-, and consequences of mounding of groundwater which can be
anticipated to occur above the naturally occurring water table
Location of nearby streams and swamps
Potable and non-potable water supply wells
Other data as appropriate.
It may be necessary to establish site groundwater conditions through instal-
lation of a series of simple observation wells prior to the actual selection of
locations and depths for permanent monitoring wells. Groundwater quality should be
monitored immediately below the water table surface near the site. As distance
from the site increases, the depth of sample withdrawal from within the groundwater
system may need to be increased or sampling at multiple depths may be required to
assure interception of affected groundwater. Monitoring wells must be located so
as to detect any influence of wastewater application on the groundwater resources.
11-.2
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Water level measurements should be accurate to 0.01 feet (1/8 inch) and refer-
enced to a permanent reference point, preferably U.S. Geological Survey datum.
Measurements should be made under static water level conditions prior to any pumping
for sample collection. All monitoring wells should be securely capped and locked
when not in use to avoid contamination.
To establish a suitable data base for reference to background conditions, a
minimum of three monthly samples should be collected from each monitoring well prior
to placing the on-land application system in operation. In cases where background
water quality adjacent to the site may be influenced by prior waste applications,
provision of monitoring wells or analysis of water quality from existing wells in
the same aquifer beyond the area of influence will be necessary.
Samples should be collected monthly during the first 2 years of operation.
After the accumulation of a minimum of 2 years of groundwater monitoring information,
modification of the frequency of sampling may be considered. The following sampling
procedures should be employed:
A measured amount of water equal to or greater than three times the amount
of water in the well and/or gravel pack should be exhausted from the well
before taking a sample for analysis. In the case of very low permeability
soils, the well may have to be exhausted and allowed to refill before a
sample is collected.
Pumping equipment should be thoroughly rinsed before use in each monitoring
well.
Water pumped from each monitoring well should be discharged to the ground
surface away from the wells to avoid recycling of flow in high permeability
soil areas.
Samples must be collected, stored, and transported to the laboratory in a
manner to avoid contamination or interference with subsequent analyses.
(See Section 6.)
Sample Analysis
Water samples collected for background water quality at wastewater application
sites should be analyzed for the following: (Note: Parameters for groundwater
monitoring at sludge application or industrial waste application sites are similar.
Additional analyses may be necessary and should be determined on an individual basis
depending on the composition of the wastes applied.)
Chloride
Specific conductance
• pH
Total hardness
Alkalinity
Ammonia nitrogen
Nitrate nitrogen
11.3
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TABLE 11.1--Probable Available Form, the Average Composition Range for
Selected Agronomic Crops, and Suggested Tolerance Levels of Heavy Metals in
Agronomic Crops When Used for Monitoring Purposes.
Probable
Available
Form
Common Average
Composition
Range*
ppm
Suggested
Tolerance
Level
ppm
Cations
Barium
Cadmium
Cobalt
Copper
Iron
Manganese
Mercury
Lithium
Nickel
Lead
Strontium
Zinc
Ba-H-
Cd++
Co-n-
Cu-n-
Fe++
Pb++
Sr++
Zn++
10-100
0.05-0.20
0.01-0.30
3-40
20-300
15-150
0.001-0.01
0.2-1.0
0.1-1.0
0.1-5.0
10-30
15-150
Anions
200
3
5
150
750
300
0.04
5
3
10
50
300
Arsenic
Boron
Chromium
Fluorine
Iodine
Molybdenum
Selenium
Vanadium
AsOi;
HBOi
CrO3"
F~
I-
MoO;
SeOjT
VO-3
0.01-1.0
7-75
0.1-0.5
1-5
0.1-0.5
0.2-1.0
0.05-2.0
0.1-1.0
2
150
2
10
1
3
3
2
Average values for corn, soybeans, alfalfa, red clover, wheat, oats,
barley, and grasses grown under normal soil conditions. Greenhouse, both soil
and solution, values are omitted.
Values are for corn leaves at or opposite and below ear leaf at tassel
stage; soybeans, the youngest mature leaves and petioles on the plant after
first pod formation; legumes, upper stem cuttings in early flower stage; cereals,
the whole plants at boot stage; and grasses, whole plants at early hay cutting
stage.
11.4
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Nitrite nitrogen
Total phosphorus
Methylene blue active substances
Chemical oxygen demand
•
• Any heavy metals or toxic substances found in the applied wastes.
After adequate background water quality information has been obtained, a mini-
mum of one sample per year, obtained at the end of the irrigation season in the case
of seasonal operations, should be collected from each well and analyzed for the
above constituents.
All other water samples should be analyzed for chlorides and specific conduc-
tance as indicators of changes in groundwater quality resulting from the waste
applied. If significant changes are noted in chloride and/or specific conductance
levels, samples should immediately be analyzed for the other parameters listed
above to determine the extent of water quality deviation from background levels.
Vegetation Monitoring
The vegetation produced on a wastewater or sludge application site may be the
most sensitive and meaningful monitor of the impact of materials applied to the site.
Uniform analytical procedures should be used. Similarly, uniform selection of the
portion of the plant to be analyzed should be used so that the information obtained
from a given site is readily comparable with other systems. (See footnote to Table
11.1.) The values in Table 11.1 have been suggested (18) as common average composi-
tion and suggested tolerance levels for monitoring purposes.
The tolerance levels suggested in Table 11.1 for agronomic crops are generalized
concentrations averaged over many crops. They are one-half less than the values
which are: toxic to animals, plant levels at which appreciable transfer of the
element from the vegetative portion of the plant to the grain occurs, and/or the
level known to be toxic to the plant itself. Therefore, the tolerance levels allow
for some elemental increases in the vegetative portion of plants without significant
increases in seed grain or immediate food chain hazards. Levels are intended only
for grain crops or hay for animals. Vegetable crops are excluded. The tolerance
levels do not apply to crops where the vegetative portion of the plant may be con-
sumed by humans.
Sampling and Analysis Methods
To permit effective comparison of monitoring data obtained over a period of
time at a wastewater or sludge application site, or to permit the comparison of data
from one site with another, it is essential to use uniform sampling and analysis
techniques wherever possible. A bulletin entitled Sampling and Analysis of Soils,
Plants, Wastewater and Sludges: Suggested Standardization and Methodology, NC-118,
North Central Regional Publication No. 230 (20), has been developed for this purpose.
Paul A. Blakeslee is Regional Sanitary Engineer, Municipal Wastewater Division,
Michigan Department of Natural Resources, Mason Building, Lansing, Mich. 48926.
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Section 12
SELECTED BIBLIOGRAPHY
I. American Public Health Association. 1971. Standard Methods for the Examination
of Waste and Wastewater. 13th ed.
2. Anonymous. 1970. Glossary of Soil Science Terms. Soil Science Society of
America, Madison, Wis.
3. Bendixen, T. W., R. P. Hill, W. A. Schwartz, and G. G. Robeck. 1968. Ridge and
Furrow Liquid Waste Disposal in a Northern Latitude. J. San. Eng. Div.,
Proc. ASCE, 94 (SA1): 147-157.
4. Black, C, A. (ed.) 1965. Methods of Soil Analysis. Part 2. Chemical and Micro-
biological Properties. Agronomy No. 9. Amer. Soc. Agron., Madison, Wis.
5. Bouwer, H. 1973. Land Treatment of Liquid Waste: The Hydrologic System. In
Proceedings of Joint Conf. on Recycling Municipal Sludges and Effluents
on Land, July 1973, Champaign, 111.
6. Carlson, C. A., P. G. Hunt, and T. B. Delaney, Jr. 1974. Wastewater Treatment
on Soils of Low Permeability. U. S. Army Engineers Waterways Exp. Sta.,
Vicksburg, Miss.
7. Christensen, L. E. 1975. An Economic and Institutional Analysis of Land Treat-
ment as a Wastewater Management Alternative for Southeastern Michigan.
Ph.D. Dissertation, Mich. State Univ.
8. Committee on Water Quality Criteria. 1972. Water Quality Criteria 1972.
Report of a joint committee of the National Academy of Sciences and the
National Academy of Engineering. U.S. GPO Stock No. 550100520.
9. Decker, W. L. 1967. Temperatures Critical to Agriculture. Univ. of Missouri
Agri. Exp. Sta., N. C. Regional Research Publication No. 174.
10. Ellis, B. G., A. E. Erickson, B. D. Knezek, R. J. Kunze, I. F. Schneider, E. P.
Whiteside, and A. R. Wolcott. 1973. Land Treatment of Wastewater in South-
eastern Michigan. Report to U.S. Army Corps of Engineers. Contract Nos.
DACW35-73-C-0163 to 0170.
11. Environmental Protection Agency. 1974. Methods for Chemical Analysis of Water
and Wastes. National Environmental Research Center, Cincinnati, Ohio.
12. Federal Register. Vol. 38, No. 174, Monday, Sept. 10, 1973.
13. Federal Water Pollution Control Act Amendments of 1972. Oct. 1972. Public Law
92-500, 92nd Congress, 5.2770.
14. Foth, H. D. and L. M. Turk. 1972. Fundamentals of Soil Science. John Wiley
and Sons, Inc.
15. Glover, T. F. 1974. Reflections on the EPA Interpretation of Best Practicable
Treatment. Dept. of Agri. Econ. and Rural Soc., The Ohio State Univ., ESO
No. 214.
12.1
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16. Glover, T. F. 1975. Land Treatment of Wastewater and Sludges. Mimeo., Dept.
of Econ. , Utah State Univ.
17. Hoeppel, R. E., P. G. Hunt, and T. B. Delaney, Jr. 1974. Wastewater Treatment
on Soils of Low Permeability. U.S. Army Engineers Waterways Exp. Sta.,
Vicksburg, Miss.
18. Melsted, S. W. 1973. Soil Plant Relationships (Some Practical Considerations
in Waste Management). In Proceedings of Joint Conf. on Recycling Municipal
Sludges and Effluents on Land, July 1973, Champaign, 111.
19. NC-12--NC-98. 1973. Guidelines for Planning and Conducting Water Quality Ex-
periments. Regional Publication.
20. NC-118. 1975. Sampling and Analysis of Soils, Plants, Waste Waters and Sludges:
Suggested Standardization and Methodology. N. C. Regional Publication 230.
21. NC-124. 1975. Guidelines for Manure Use and Disposal in the Western Region,
USA. Washington State Univ., College of Agr., Res. Center Bull. 814.
22. Page, A. L. 1973. Fate and Effects of Trace Elements in Sewage Sludge when
Applied to Agricultural Land. Environmental Protection Agency.
23. Pound, C, D. and R. W. Crites. 1973. Wastewater Treatment and Re-use by Land
Application. Report by Metcalf and Eddy, Inc. to U.S.E.P.A., Vols. I and
II. EPA-66/2-73-006a and b. U.S. GPO.
24. Proceedings of the Joint Conference on Recycling Municipal Sludges and Effluents
on Land. 1973. Sponsored by U.S.E.P.A., U.S.D.A., and the Nat. Assoc. of
State Universities and Land Grant Colleges. Library of Congress Cat. No.
73-88570.
25. Soil Survey Staff. 1951. Soil Survey Manual, U. S. Dept. of Agriculture Hand-
book No. 18.
26. Sopper, W. E. 1973. Crop Selection and Management Alternatives -- Perennials.
Jn Proceedings of Joint Conf. on Recycling Municipal Sludges and Effluents
on Land, July 1973, Champaign, 111.
27. Sullivan, R, H., M. M. Conn, and S. S. Baxter. 1973. Survey of Facilities Us-
ing Land Application of Wastewater. Report of the American Public Works
Association to U.S.E.P.A., EPA-430/9-73-006.
28. Thomas, R. E. and C. C. Harlen, Jr. 1972. Experiences with Land Spreading of
Municipal Effluents, First Annual IFAS Workshop on Land Renovation of
Wastewater, Tampa, Fla. (June 1972).
29. U.S. Environmental Protection Agency. 1975. Water Quality Strategy Paper.
Third ed. Planning Assistance and Policy Branch, East-Room 815, 401 M St.,
S.W., Washington, D.C. 20460, Mail code WH-554.
30. White, R. K,, M. Y. Hamdy, and T. H. Short. 1974. Systems and Equipment for
Disposal of Organic Wastes on Soil. Ohio Agri. Res. and Dev. Center, Woos-
ter, Res. Circ. 197.
12.2
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Section 13
GLOSSARY OF TERMS
Acre inches/year -- The amount (inches) of water or effluent spread on 1 acre of
land in 1 year.
Activated sludges -- Sludge floe produced in raw or settled wastewater by the growth
of zoogleal bacteria and other organisms in the presence of dissolved oxygen
and accumulated in sufficient concentration by returning floe previously formed.
Product is waste-activated sludge.
Adsorbed - adsorption -- The attraction of ions or compounds to the surface of a
solid. Soil colloids adsorb large amounts of ions and water.
Aeration -- The process by which air in the soil is replaced by air from the atmos-
phere .
Aerobic -- (i) Having molecular oxygen as a part of the environment. (ii) Growing
only in the presence of molecular oxygen.
Aerobic sludge digestion -- Digestion of organic waste solids by means of aeration.
Aerosols -- Microscopic droplets dispersed in the atmosphere.
Agronomic -- Crops having economic importance in agriculture.
Alkalinity -- A soil or material with pH of 8.5 or higher, or with a high exchange-
able sodium content (15% or more of the exchange capacity).
Anaerobic -- The absence of molecular oxygen. Living or functioning in the absence
of air or free oxygen.
Anaerobic digested sludge -- The stabilization of organic waste solids brought about
through the action of microorganisms in the absence of elemental oxygen.
Annual crop -- A crop which completes its entire life cycle and dies within 1 year
or less; i.e., corn, beans.
Aquifer -- Stratum below the surface capable of holding water.
Arid -- Dry; limited moisture.
Available moisture -- The portion of the soil water readily available for plant use.
Basin irrigation -- An efficient system of irrigating in which a field or orchard
is divided into basins which are filled with water.
Best practicable treatment -- Referring to sewage treatment as the most operational
treatment system given local conditions and wastewater content.
Biological treatment -- Forms of wastewater-treatment in which bacterial or biochem-
ical action is intensified to stabilize, oxidize, and nitrify the unstable or-
ganic matter present. Intermittent sand filters, contact beds, trickling fil-
ters, and activated sludge processes are examples.
13.1
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BOD — Biochemical Oxygen Demand. A standard test used in assessing wastewater
strength. The quantity of oxygen used in the biochemical oxidation of organic
matter in a specified time, at a specified temperature, and under specified
conditions.
BOD5 -- 5-day Biochemical Oxygen Demand. The quantity of oxygen used in the biochem-
ical oxidation of organic matter after 5 days, at a specified temperature, and
under specified conditions.
Bulk density — The mass of dry soil per unit bulk volume including the air space.
The bulk volume is determined before drying to constant weight at 105° C.
Bunchgrass — Bunchgrasses lack stolons and form thick bunches such as fescue and
wheat grass.
Calcareous — Soil containing sufficient calcium carbonate to effervesce visibly
when treated with cold 0.1 N hydrochloric acid.
_fy
Carbonate — A compound containing the radical COj *•.
Cation exchange capacity -- The sum total of exchangeable cations a soil can adsorb.
Expressed in milliequivalents per 100 grams of soil or other adsorbing material
such as clay.
Central pivot system -- An irrigation system in which a lateral line supported by
towers rotates about a pivot point.
Chelating properties — The property of certain chemical compounds in which a metal-
lic ion is firmly combined with the compound by means of multiple chemical bonds.
Clay — Soil particles less than 0.002 mm in diameter.
Closed drainage system -- A landscape where essentially all the products derived
within the perimeter are trapped within the system and are not transmitted to
streams or water supplies.
COD -- Chemical Oxygen Demand. The oxygen consumed by the chemical oxidation of
material in water.
Composite --To make up a sample of distinct portions so the sample is representa-
tive of the total material being sampled rather than any single portion.
Conducting layers -- Layers of soil which contain the property of enabling water
and fluids to pass through with little resistance.
Cost effectiveness -- The least cost project or means to achieving a specific goal.
Cover crop -- A crop grown between periods of regular crops for adding organic mat-
ter to soil, and/or protection against erosion.
Denitrification — The biochemical reduction of nitrate or nitrite to gaseous nitro-
gen either as molecular nitrogen or as an oxide of nitrogen.
Detritus -- Any disintegrated material resulting from a larger material being rubbed
or worn away; debris.
13.2
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Drilled -- Those seeds or crops which have been planted in rows by means of a drill.
Basement, use right -- A right afforded a party to make limited use of another par-
ty's real property.
Effluent -- The liquid substance, predominately water, containing inorganic and
organic molecules of those substances which do not precipitate by gravity.
Electrical conductivity -- An expression of the readiness with which an electrical
impulse (generated by ionic activity) flows through a water or soil system.
Electrode method -- A method of analysis by use of electrodes for measuring various
substances.
Ensiling -- The process of placing green plant material in a silo, pit, trench, or
stack for fermentation and storage.
EPA -- Environmental Protection Agency.
Eutrophication -- The process in which the rate of plant growth is faster (due to
the presence of an- abundant supply of nutrients) than the rate of decomposition.
Evapotranspiration -- The combined loss of water from a given area, and during a
specified period of time, by evaporation from the soil surface and by trans-
piration from plants.
External force -- In the economic sense, a force externally imposed by one economic
agent on other economic agents. Such forces involve costs and/or benefits and
are sometimes referred to as externalities or spillover effects.
Fecal coliforms -- A type of facultative, anaerobic, Gram-negative, rod-shaped cells
of nonspore-forming bacteria originating from fecal material.
Fee simple -- An estate in land having unqualified ownership and power of disposition.
Fescue pastures -- Pastures or tracts of land used for grazing which consist of the
species of grass of the genus Festuca, family Gramineae.
Forage crop -- A crop such as hay, pasture grass, legumes, etc. which is grown pri-
marily as forage or feed for livestock.
Friable condition -- A soil with aggregates which can be readily ruptured and crushed
with application of moderate force. Easily pulverized or reduced to crumb or
granular structure.
Furrow irrigation -- A method of irrigating in which water is run in small ditches,
furrows, or corrugations, usually spaced close enough together to afford lat-
eral penetration between them.
Geologic -- Related to or based on geology or the properties of the earth surface
and subsurface soil and rock formations.
Glacial outwash -- Stratified glacial drift which is water built. The material is
arranged in layers of material of different texture.
13.3
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Glacial till -- The unconsolidated, heterogeneous mass of clay, sand, pebbles, and
boulders deposited by receding ice sheets.
Grab sample -- A sample obtained randomly at one time. This may or may not be rep-
resentative of an entire composite of samples.
Groundwater quality -- The degree of purity of the water obtained from the zone of
saturation (well water, subsurface or underground water).
Groundwater recharge -- Return of surface water to groundwater aquifers.
Heavy metals -- Generally, those elements in the periodic table of elements which
belong to the transition elements. They may include essential micronutrients
and other nonessential elements.
Holding basin (storage lagoon) -- A natural or artificially created space which has
the shape and character of confining material enabling it to hold water. It
may contain raw or partially treated wastewater in which aerobic or anaerobic
stabilization occurs.
Host-specific pest -- A parasite or pest which can live in only one host, to which
it is therefore said to be specific.
Humid areas -- Geographic areas where the climate has sufficient precipitation to
support a forest vegetation. Precipitation may range from 20-60 inches annually.
Humus (residual humus) -- Organic matter in the soil which has reached an advanced
stage of decomposition and has become colloidal in nature. It is usually char-
acterized by a dark color, a considerable nitrogen content, and chemical prop-
erties such as a high base-exchange capacity.
Hydraulic capabilities -- Fluids, usually water, which are moving or at rest under
forces of gravity or pressure.
Hydrologic -- Relating to the properties and movement of water within a soil system
and the underlying rock formations.
Immobilized -- The action or reaction by which a substance (element) is rendered
immovable; fixed, as by organic matter or clay.
Impermeable pans -- Zones within the soil which restrict the movement of gases, li-
quids, and roots.
Impervious -- Resistant to penetration by fluids or by roots.
Industrial organics -- Materials such as pesticides, chlorinated plasticizers, fire
retardants, etc.
Infiltration capacity — The maximum rate at which a soil, in a given condition at
a given time, can absorb water, commonly expressed in inches of depth per hour.
Interlacing rhizomes -- The crossing and interwoven stems which grow partly or en-
tirely beneath the surface of the ground, often having scale-like leaves.
Interstratified bedrock — Alternating layers of different bedrock; layers occurring
between beds of different material.
13.4
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Knifing -- The injection of a substance below the soil surface.
Leaching -- The removal of soluble constituents from soils or other materials by
percolating water.
Loading parameter -- Variables such as water, metals, soluble salts, suspended
solids, nitrogen, or phosphorus which may limit wastewater or sludge application.
Lodging -- Pertaining to field crops --to break, bend over, or lie flat on the
ground, sometimes forming a tangle. Lodging may be caused by high nitrogen
levels in the soil, lush growth, wind and heavy rain, and plant diseases.
Loess -- A massive deposit of silt (tan or buff colored), with particles typically
angular and uniform in size. It is usually calcareous, often contains concre-
tions of calcium carbonate and shows lamination or bedding.
Major nutrient (macronutrient) -- A chemical element necessary in large amounts
(usually > 1 ppm in the plant) for the growth of plants; i.e., nitrogen,
phosphorus, potassium.
Matrices — That which gives origin or form to a thing, or serves to enclose it.
Metal toxicities -- Toxicities arising from too high levels of metals in the soil.
These could be due to cadmium, nickel, zinc, copper, etc. at such levels that
they cause stunted or reduced growth and micronutrient imbalances within the
plant.
Methylene blue active substances -- A measure of the amount of anionic surfactants
(detergents) present in water.
MOD -- Millions of gallons per day.
Micronutrient -- A chemical element necessary in only extremely small amounts
(< 1 ppm in the plant) for growth of plants; i.e., B, Cl, Fe, Mn, Mo, Zn, Cu.
Microorganism --An organism so small it cannot be seen clearly without the use of
a microscope.
Mineralized — The conversion of an element in organic combination to its inorganic
form as a result of microbial decomposition.
Monoculture -- Cultivation of a single crop, such as wheat or cotton, to the exclu-
sion of other possible uses of the land.
Mulch -- Soil, straw, peat, or any other loose material placed on the ground to
conserve soil moisture, or prevent undesirable plant growth or soil erosion.
NC-98 -- North Central Regional Committee of the State Agricultural Experiment Sta-
tions and Cooperative State Research Service titled "Environmental Accumulation
of Nutrients as Affected by Soil and Crop Management."
NC-118 — North Central Regional Committee of the State Agricultural Experiment Sta-
tions and Cooperative State Research Service titled "Utilization and Disposal
of Municipal, Industrial and Agricultural Processing Wastes on Land."
Ponding -- The accumulation of free water on the soil surface.
13.5
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Potable -- Water suitable for drinking.
Precipitated -- To separate out in solid form from a solution.
Precipitation surpluses -- Excessive rainfall.
Primary sludge (raw sludge) -- Sludge obtained from a primary settling tank, which
is the first settling tank for removal of settleable soils through which waste-
water is passed in a treatment work.
Putrescible wastewater constituents -- Microbially decomposed in the absence of
oxygen.
Renovation - renovated water — Water which has undergone treatment through chem-
ical or biological means whereby impurities have been removed, thus making it
more desirable for a particular use.
Risk statement — A statement of probability with reference to the probability of
occurrence, impact, and duration of an event.
Row crop -- A crop such as corn, beans, sugar beets, cotton, etc., usually grown
or cultivated in rows.
Runoff — That portion of total precipitation finding its way into drainage chan-
nels. It consists of ever varying proportions of both surface runoff and
groundwater runoff.
Sand -- Soil particles between 2 and 0.005 mm in diameter.
Secondary treatment — The treatment of wastewater by biological methods after pri-
mary treatment by sedimentation.
Sedimentation -- Deposit of sediment by natural or mechanical means.
Seeps — A spot where water oozes out slowly from the soil and gathers in a pool
or produces merely a wet place, usually on a hillside as a hill base.
Selective breeding -- The breeding of selective plants or animals chosen because of
certain desirable qualities or fitness, as contrasted to random or chance
breeding.
Semi-arid -- The climate, characteristic of the regions intermediate between the
true deserts and subhumid areas, under which precipitation effectiveness is
such that a vegetation of scattered short grasses, bunchgrasses, or shrubs
prevails.
Shallow discing — The process by which debris is chopped into pieces and put under
the soil by use of a disk, normally less than 5 inches.
Shrink-swell potential -- The potential of a soil material to change volume as a
result of wetting or drying.
Side roll laterals -- Laterals used in irrigating low-growing row crops and forages.
They are mounted on wheels with the pipeline as the axle. A length of flexible
hose is used to make the connection to the main line.
13.6
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Silt -- Soil particles between 0.05 and 0.002 mm in diameter.
Soil compaction — The process by which soil grains are rearranged to decrease void
space and bring them into closer contact with each other, thereby increasing
the weight or bulk material per cubic foot.
Soil horizon -- A layer of soil approximately parallel to the land surface and dif-
fering from adjacent genetically related layers.
Soil profile — A vertical section of the soil from the surface through all its
horizons, including C horizons.
Soil structure -- The combination or arrangement of primary soil particles into
secondary particles, units, or peds.
Sod former -- Any crop or vegetative cover which quickly forms a heavy, close-knit,
top growth over the surface of the soil and a root system which binds the soil
particles together, thus forming a sod, such as white clover or bluegrass.
Specific conductance -- A measure of the capacity of water to convey an electrical
current. This property is related to the total concentration of ionized sub-
stances in a water and changes in the specific conductance at a given monitor-
ing well location give an indication of a change in groundwater quality.
Sprinkler irrigation (spray irrigation) -- Irrigation by means of above-ground ap-
plicators which project water outward through the air, making it reach the
soil in droplet form.
Static water level -- Equilibrium water level reached in an observation or monitor-
ing well after an extended period.
Strata -- Layers or beds of rock.
Structural carbon -- Structural forms of most organic molecules are made up of a
carbon skeleton with other elements bonded to it.
Submarginal land -- Land incapable of sustaining a certain use or ownership status
economically.
Substratum -- The C horizon of a soil.
Surface irrigation — Irrigation distribution of water over the soil surface by
flooding or in furrows for storage in the soil for plant use.
Suspended solids -- Solid particles which do not precipitate out of solution or do
not easily filter out. They may be colloidal in nature.
Texture (soil texture) -- The relative proportion in a soil of the various size
groups of individual soil grains (sand, silt, and clay).
Tight subsoil -- A subsoil which is very compact and permits only very slow move-
ment of water.
Tillage operations -- Working the soil to bring about more favorable conditions for
plant growth.
13.7
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Tolerance level — The highest level an organism can resist or endure before becom-
ing affected.
Toxic trace organics -- See industrial organics.
Trickling filter — A bed of crushed stone, gravel, or cinders of relatively large
size and usually about 5 feet or more thick. Sewage is applied at the surface
and the solids precipitate out during their descent through the bed. Aerobic
bacteria decompose the solids.
Uncertainty — Usually refers to an event about which nothing is known with respect
to impact, duration, and probability of occurrence.
Underdrainage — That drainage consisting of drain tiles placed in trenches deep
enough to allow the covering soil to be cultivated and the profile adequately
drained.
uptake — The process by which plants take elements from the soil. The uptake of
a certain element by a plant is calculated by multiplying the dry weight by
the concentration of the element.
U.S.G.S. datura — Elevation relative to mean sea level established by the United
States Geological Survey. United States Geodetic Survey.
vacuum filtration — Separation of substances by use of a filtering system with
the aid of a vacuum.
Volatilization - vaporization — The conversion of a liquid or solid into vapors.
W-124 — Western Regional Committee of the State Agricultural Experiment Stations
and Cooperative State Research Service titled "Soil as a Waste Treatment
System."
Water table — The upper surface of groundwater or that level below which the soil
is saturated with water; locus of points in soil water at which the hydraulic
pressure is equal to the atmospheric pressure.
Wastewater loadings — The amount of wastewater applied per acre per unit of time.
Watershed — The total runoff from a region which supplies the water of a river or
lake; a catchment area or drainage basin.
yield goals — The highest anticipated or expected yield a field should produce.
13.8
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Section 14
APPENDICES
Appendix A
Double Ring Infiltrometer Method for Measuring Soil Infiltration Rates
Ref. : Bertrand, A. R. 1965. Rate of Water Intake in the Field. In Methods of
Soil Analysis, Part 1, Monograph No. 9, American Society of Agronomy, Madi-
son, Wis.
Needed equipment and supplies:
1. Metal cylinders: Prepare three to preferably five cylinders for use in a single
test, using smooth, cold-rolled steel or galvanized steel of thickness not to
exceed 0.08 inch (approximately 14 gauge) unless a sharpened cutting edge is pro-
vided. Make the length at least 10 inches and preferably 12 to 14 inches. Make
the inside diameter at least 12 inches and preferably more, making the diameters
such that the cylinders will nest inside each other if desired. Butt-weld the
longitudinal seams, and grind them to a reasonably smooth finish. If a set of
buffer cylinders is to be used instead of an earthen dam to provide a buffer com-
partment, make these cylinders in the manner described above; but use 10-gauge
or heavier metal, use a length of 8 inches, use a diameter at least 8 inches lar-
ger than the measuring cylinders, and weld a reinforcing strip around the top.
2. Driving plate: Use a piece of steel plate at least 1/2 inch thick and from 2
to 4 inches larger than the diameter of the largest measuring cylinder. Weld
lugs to the lower face to keep the plate approximately centered on the cylin-
ders. If desired for greater ease in carrying the plate, weld a handle of
steel rod 1/2 inch in diameter to one edge.
3. Driving hammer: A 16-lb. sledge hammer, used with a tamping blow rather than
a swinging blow, is adequate for many soils. To make a heavier and better ham-
mer, attach a handle to one edge of a steel block weighing about 30 Ib. (this
weight is provided by a block having dimensions about 8 by 2 inches). Alter-
natively, attach a 1-1/4 inch by 3 inch, banded, malleable-iron reducer to a
4-foot length of standard 1-1/4 inch galvanized pipe, and fill the reducer and
pipe with 15 to 20 Ib. of lead.
4. Water supply: Use 50-gallon steel drums, 10-gallon milk cans, or other suit-
able containers for transporting water to the site of the measurements. Use
one or more buckets of 10 to 12-quart capacity to convey water to the cylinder.
Employ water suitable for irrigation.
5. Puddling protection device.- Use a piece of folded burlap, cloth, heavy paper,
or loosely fitting 1/4-inch board inside the central cylinder to protect the
soil surface from puddling when water is first applied.
6. Timing device: Use a watch or other timepiece which can be read to 1 minute
or less.
7. Hook gauge: Grind a 16-inch length of welding rod to a fine point at one end,
and bend this end through 180° to form a hook in which the pointed end is paral-
lel with the long axis of the rod. Solder a flat piece of brass about 3/4 by
14.1
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1/4 by 1/16 inch in size to the welding rod about 3 inches from the end oppo-
site the hook, placing the long dimension of the brass piece perpendicular to
the axis of the welding rod. Use this assembly in connection with a triangu-
lar engineer's scale to measure the distance of the water surface in the cyl-
inder below a reference point. Alternatively, use the manometer described
below in 8 or the constant-head device in 9.
8. Manometer: As an alternative to the hook gauge for measuring the level of
water inside the central cylinder, prepare a manometer in the following manner.
Secure a graduated pipette of perhaps 30 cm. length and several millimeters in-
side diameter, and cut off the lower restricted end. Then cut a piece of 2 by
12-inch board in the shape of a right triangle with one angle of about 30° and
and with the hypotenuse of a length slightly greater than that of the graduated
pipette. Fasten the pipette to the edge of the triangle which forms the hypot-
enuse, and fasten the side which forms the other leg of the 30° angle to a tri-
angular piece of 1/4-inch steel plate which is set on three leveling pins and
is placed outside the infiltrometer. Before each use, carefully level the plat-
form. Before adding water to start the infiltration run, attach one end of a
piece of flexible tubing to the bottom of the pipette, and lead the other end
over the top of the two cylinders to the bottom of the inner cylinder. Immedi-
ately following addition of water to the inner cylinder, suck on the top of the
pipette to cause water to fill the flexible tube. Then read the position of
the meniscus on the pipette scale, and multiply the values by the appropriate
factor to obtain readings of vertical movements of the water surface in inches
or centimeters as desired. The conversion factor will remain the same as long
as the platform is accurately leveled.
9. Constant-head device: If a constant head is to be maintained in the cylinder,
connect the main water supply tank to a float valve attached to the side of the
measuring cylinder (or to a stake if the furrow or basin method is used). Use
a siphon tube of sufficient size (usually 1/2-inch diameter) to make the connec-
tion.
Procedure;
Select a general area that is representative for the purpose of the measurement.
Examine and describe the soil profile conditions of texture, structure, water con-
tent, and adsorbed sodium, with particular reference to the first foot. Secure sam-
ples for measuring the adsorbed sodium content (where sodium may be a problem) and
the water content. Record the kind of crop and the stage of growth, and describe
any surface litter or mulch and the condition of the soil surface -- freshly culti-
vated, cloddy, crusted, cracked, etc. Make note of any other condition observed
which might have an influence on rate of water intake.
To provide for concurrent measurements on three or more sites, select the exact
sites for the measurements within a limited area, normally 1/2 acre or less. Unless
the objective is to make measurements of special conditions, avoid areas which may
be affected by unusual surface disturbance, animal burrows, stones which might dam-
age the cylinder, animal traffic, or machine traffic.
Set a cylinder in place and press it firmly into the soil. For cylinders less
than 24 inches in diameter, place the driving plate on the cylinder, stand on the
plate, and drive the cylinder into the soil by tamping the plate with the driving
hammer. Drive the cylinder in vertically, using a carpenter's level as needed. Do
not drive the cylinder into the soil irregularly so that first one side and then the
other goes down. This procedure^ produces a poor bond between the cylinder wall and
14.2
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the soil, and it disturbs the soil core within the cylinder. If the cylinder should
enter the soil at an angle, remove it and reset it in another location. Drive the
cylinder into the soil to a depth of approximately 4 inches.
Around the measuring cylinder, place a buffer cylinder having a diameter at
least 8 inches greater. Drive this cylinder into the soil to a depth of 2 to 4
inches by tamping it around the circumference with the driving hammer. Strictly
vertical movement of this cylinder into the soil is not particularly important. As
an alternative to the buffer cylinder, construct a buffer pond by throwing up a low
(3 to 6 inches) dike around the cylinder, avoiding disturbance of the soil inside
the dike, and keeping the inside toe of the dike at least 6 inches from the cylinder.
Place burlap or other puddling protection device on the soil within the central
cylinder. Then fill the buffer pond on the outside with water to a depth of about
2 inches, and maintain approximately the same depth throughout the period of obser-
vation. (The depth of water in the buffer pond is not critical as long as a supply
of water is always available for infiltration into the soil.) Immediately after
adding water to the buffer pond, fill the central cylinder with water to the desired
depth (usually 1 to 3 inches), remove the puddling protection device, and make a
measurement of the water surface elevation by a hook gauge (or manometer if desired).
Use the cylinder edge for the reference level, and mark the cylinder so that all sub-
sequent measurements can be made at the same point on the cylinder. Alternatively,
if the basin or furrow method is used, employ a stake to provide a reference level.
Record the hook gauge reading and the time at which the observation was made. Carry
out these operations quickly, so that errors from intake during the operations will
be small.
Make additional hook gauge measurements at intervals, and record the water level
and the time. For most soils, observations at the end of 1, 3, 5, 10, 20, 30, 45,
60, 90, and 120 minutes, and hourly thereafter, will provide adequate information.
Make observations more frequently as needed on soils having a high rate of intake.
As a general rule, the intake between measurements should not exceed 1 inch. Con-
tinue measurements until the rate of intake is almost constant.
When the water level has dropped 1 or 2 inches in the cylinder, add sufficient
water to return the water surface approximately to its initial elevation. Record
the level and time just before filling and-the level after filling. Keep the in-
terval between these two readings as short as possible to avoid errors caused by
intake during the refilling period. (In analyzing the results, the assumption is
made that the refilling is instantaneous.)
If a constant water level in the cylinder or basin is maintained by a float
valve, measure the rate of depletion of water in the supply tank by a hook gauge,
manometer, or automatic water-stage recorder.
14.3
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Robert Taft Sanitary Engineering Center Percolation Test
Ref.: U. S. Dept. of Health, Education and Welfare. 1967. Manual of Septic-Tank
Practice. Public Health Service Publication No. 526, pp. 4-8.
Procedure:
1. Number and location of tests: Six or more tests shall be made in separate test
holes spaced uniformly over the proposed absorption field site.
2. Type of test hole: Dig or bore a hole, with horizontal dimensions of 4 to 12
inches and vertical sides to the desired depth. To save time, labor, and vol-
ume of water required per test, the holes can be bored with a 4-inch auger.
3. Preparation of test hole: Carefully scratch the bottom and sides of the hole
with a knife blade or sharp-pointed instrument, to remove any smeared soil sur-
faces and to provide a natural soil interface into which water may percolate.
Remove all loose material from the hole. Add 2 inches of coarse sand or fine
gravel to protect the bottom from scouring and sediment.
4. Saturation and swelling of the soil: It is important to distinguish between
saturation and swelling. Saturation means that the void spaces between soil
particles are full of water. This can be accomplished in a short period of
time. Swelling is caused by intrusion of water into the individual soil par-
ticles. This is a slow process, especially in clay-type soil, and is the rea-
son for requiring a prolonged soaking period.
In the conduct of the test, carefully fill the hole with clear water to a mini-
mum depth of 12 inches over the gravel. In most soils, it is necessary to re-
fill the hole by supplying a surplus reservoir of water, possibly by means of
an automatic syphon, to keep water in the hole for at least 4 hours and pref-
erably overnight. Determine the percolation rate 24 hours after water is first
added to the hole. This procedure is to insure that the soil is given ample
opportunity to swell and to approach the condition it will be in during the
wettest season of the year. Thus, the test will give comparable results in
the same soil, whether made in a dry or a wet season. In sandy soils contain-
ing little or no clay, the swelling procedure is not essential, and the test
may be made as described under 5C, after the water from one filling of the hole
has completely seeped away.
5. Percolation rate measurement: With the exception of sandy soils, percolation
rate measurements should be made on the day following the procedure described
under 4, above.
A. If water remains in the test hole after the overnight swelling period, adjust
the depth to approximately 6 inches over the gravel. From a fixed reference
point, measure the drop in water level over a 30-minute period. This drop is
used to calculate the percolation rate.
B. If no water remains in the hole after the overnight swelling period, add
clear water to bring the depth of water in the hole to approximately 6 inches
over the gravel. From a fixed reference point, measure the drop in water level
at approximately 30-minute intervals for 4 hours, refilling 6 inches over the
gravel as necessary. The drop which occurs during the final 30-minute period
is used to calculate the percolation rate. The drops during prior periods pro-
14.4
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vide information for possible modification of the procedure to suit local cir-
cumstances.
C. In sandy soils (or other soils in which the first 6 inches of water seeps
away in less than 30 minutes, after the overnight swelling period), the time
interval between measurements should be taken as 10 minutes and the test run
for 1 hour. The drop which occurs during the final 10 minutes is used to cal-
culate the percolation rate.
14.5
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Appendix B
Sample Calculations to Determine Sludge Application Rates
on Agricultural Land (Section 3}
Sludge: 2% NH4-N, 0% N03-N, 5% total N, 2% P, 0.2% K
Zn, 10,000 ppm; Cu, 1,000 ppm; Ni, 50 ppm; Pb, 5,000 ppm; Cd, 10 ppm
Soil: Silt loam, CEC = 20 meq/100 g; fertilizer recommendations from soil tests
are 25 Ib. of P per acre and 100 Ib. of K per acre.
Previous applications: 10 tons/acre for 2 previous years
From Table 3.4: 180 bu. corn — 240 Ib. N, 44 Ib. P, 199 Ib. K
A. Calculate annual rate based on N and Cd
1. Available N in sludge
2% NH4-N + 0% N03-N = 2% 1^
5% total N = 2% N1 = 3% NQ
Incorporated sludge application
Lb. available N/ton sludge = 20 x 2% + 4 x 3%
= 40 + 12
= 52
52 Ib. available N/ton sludge
2. Residual N
From Table 3.5 for 3% organic N
a) Sludge added 1 year earlier
10 tons/acre x 1.4 Ib. N/ton = 14 Ib. N
b) Sludge added 2 years earlier
10 tons/acre x 1.4 Ib. N/ton = 14 Ib. N
c) Residual N = 28 Ib.
3. Sludge application Rate
a) 240 Ib. needed - 28 Ib. residual = 212 Ib. from sludge
b> 5221lb.1Nb;ton sludge = 8.7 tons/acre
c) Calculate application rate for 2 Ib. Cd/acre
" tons/acre • 10° tons/acre
14.6
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4. The lower amount is applied =8.7 tons sludge/acre
B. Calculate total sludge amount which may be applied
Based on Table 3.3, maximum amounts are calculated as follows:
1)
2)
3)
4)
5)
Metal
Maximum
Amount
Ib./acre
Pb 2000
Zn 1000
Cu 500
Ni 500
Cd 20
The lowest amount
limited by Zn at
Cone.
in
Sludge
Tons of
Sludge/ Acre
Ppm
5000 200
10,000 5£
1000 250
50 5000
10 1000
is from equation 2. Thus,
50 tons/acre.
Calculation
2000 Ib. Pb/acre
5000 ppm Pb x .002
_ 1000 Ib. Zn/acre
10,000 ppm Zn x .002
500 Ib. Cu/acre
1000 ppm Cu x .002
500 Ib. Ni/acre
50 ppm Ni x .002
20 Ib. Cd/acre
10 ppm Cd x .002
sludge application is
C. Calculate fertilizer needed
1. P fertilizer
8.7 tons/acre x 2% P x 20 = 358 Ib. P/acre
Fertilizer recommendation is 25 Ib. P/acre
No fertilizer P needed
2. K fertilizer
8.7 tons/acre x 0.2% K x 20 = 34.8 Ib. K/acre
Fertilizer recommendation is 100 Ib. K/acre
Fertilizer K needed = 65 Ib./acre
14.7
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Appendix C
Some Useful Factors and Conversions
1. 1 acre-inch of liquid = 27,154 gallons = 3,630 ft.3 = 102,787 liters
2. 1 cm-hectare of liquid = 100,000 liters = 100 m.3
3. 1 metric ton = 1,000 kg. = 2,205 Ib.
4. Cubic feet per second x 5.39 x mg./liter = Ib./day
5. Million gallons per day x 8.34 x mg./liter = Ib./day
6. 1 acre = 4,840 yards2 = 43,560 feet2 = 4,047 meters2 = 0.4047 hectare
7. Acre-inches x 0.226 x mg./liter = Ib./acre
8. ha-cm x 0.1 x mg./liter = kg./hectare
9. English-metric conversions
a. acre-inch x 102.8 = meter3
b. quart x 0.946 = liter
c. English ton x 0.907 = metric ton
d. English tons/acre x 2.242 = metric tons/hectare
e. Ib./acre x 1.121 = kg./hectare
f. 1 ft.3 = 7.48 gallons = 28.3 liters = 62.4 Ib. water
g. 1 Ib. = 0.454 kg.
14.8
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Appendix D
PUBLICATIONS PERTINENT TO
Application of Sewage Sludge and Wastewater to Agricultural Land
A. Proceedings of Conferences and Symposia
1. Recycling Treated Municipal Wastewater and Sludge Through Forest and Crop Land.
Edited by W. E. Sopper and L. T. Kardos. Symposium held August 21-24, 1972.
The Pennsylvania State University Press, University Park, Pa,
2. Recycling Municipal Sludges and Effluents on Land. Joint conference held July
9-13, 1973, Champaign, 111. National Association of State Universities and
Land-Grant Colleges, Washington, D.C.
3. Ultimate Disposal of Wastewaters and Their Residuals. Symposium held April
26-27, 1973, Durham, N.C. North Carolina Water Resources Research Institute,
Raleigh, N.C.
4. Land for Waste Management. Conference held Oct. 1-3, 1973, in Ottawa, Ontario.
The Agricultural Institute of Canada, Ottawa, Ont.
5. Land Disposal of Municipal Effluents and Sludges. Conference held March 12-13,
1973, at Rutgers Univ., New Brunswick, N.J. EPA-902/9-73-001.
6. Wastewater Use in the Production of Food and Fiber--Proceedings. Conference held
March 5-7, 1974, at Oklahoma City, Okla. EPA-660/2-74-041, June 1974.
7. Municipal Sludge Management. Conference held June 11-13, 1974, in Pittsburgh,
Pa. Information Transfer, Inc., Washington, D.C.
8. Municipal Sludge Management and Disposal. Conference held August 18-20, 1975,
in Anaheim, Calif. Information Transfer, Inc., Rockville, Md.
9. Virus Survival in Water and Wastewater Systems. Edited by J. F. Malina, Jr.
and B. P. Sagik. Symposium held in April 1974 at the University of Texas-
Austin. Center for Research in Water Resources, University of Texas, Austin,
Texas.
B. EPA Reports — Sewage Wastewaters and Sludge
1. Survey of Facilities Using Land Application of Wastewater, by R. H, Sullivan,
M. M. Cohn, S. S. Baxter. EPA-430/9-73-006, July 1973.
2. Wastewater Treatment and Reuse by Land Application - Volume I - Summary, by
C. E. Pound and R. W. Crites. EPA-660/2-73-006a, August 1973.
3. Wastewater Treatment and Reuse by Land Application - Volume II, by C. E. Pound
and R. W, Crites. EPA/660-2-73-006b, August 1973.
4. Renovation of Secondary Effluent for Reuse as a Water Resource, by L. T. Kardos,
W. E. Sopper, E. A. Myers, R. R. Parizek, and J. B. Nesbitt. EPA-660/2-74-016,
Feb. 1974.
14.9
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5. Feasibility of Overland Flow for Treatment of Raw Domestic Wastewater, by R. E.
Thomas, K. Jackson, and L. Penrod. EPA-660/2-74-087, Dec. 1974.
6. Evaluation of Land Application Systems, by C. E. Pound, R. W. Crites, D. A.
Griffes. EPA-430/9-75-001, March 1975.
7. A Guide to the Selection of Cost-Effective Wastewater Treatment Systems, by
R. H. Van Note, P. V. Hebert, R. M. Patel, C. Chupek, and L. Feldman. EPA-430/
9-75-002, July 1975.
8. Costs of Wastewater Treatment by Land Application, by C. E. Pound, R. W. Crites,
and D. A. Griffes. EPA-430/9-75-003, June 1975.
9, Land Application of Sewage Effluents and Sludges: Selected Abstracts, by Water
Quality Control Branch, Robert S. Kerr Environmental Research Laboratory, Ada,
Okla. EPA-660/2-74-042, June 1974.
10. Fate and Effects of Trace Elements in Sewage Sludge When Applied to Agricultural
Lands, by A. L. Page. EPA-670/2-74-005, Jan. 1974.
11. Process Design Manual for Sludge Treatment and Disposal, Office of Technology
Transfer, USEPA. EPA-625/1-74-006, Oct. 1974.
12. Review of Landspreading of Liquid Municipal Sewage Sludge, by T. E. Carroll,
D. L. Maase, J. M. Genco, and C. N. Ifeadi. EPA-670/2-75-049, June 1975.
13. Trench Incorporation of Sewage Sludge in Marginal Agricultural Land, by J. M.
Walker, W. D. Burge, R. L. Chaney, E. Epstein, and J. D. Menzies. EPA-600/2-
75-034, Sept. 1975.
C. EPA Reports — Food Processing Wastes
1. Proceedings Fifth National Symposium on Food Processing Wastes, held April 17-19,
1974, in Monterey, Calif. EPA-660/2-74-058, June 1974.*
2. Wastewater Characterization for the Specialty Food Industry, by C. J. Schmidt,
J. Farquhar, and E. V. Clements, III. EPA-660/2-74-075, Dec. 1974.
3. Proceedings Third National Symposium on Food Processing Wastes, held March 28-30,
1972, in New Orleans, La. EPA-R2-72-018, Nov. 1972.*
4. Waste Control and Abatement in the Processing of Sweet Potatoes, by C. Small-
wood, Jr., R. S. Whitaker, and N. V. Colston. EPA-660/2-73-021, Dec. 1974.
5. Egg Breaking and Processing Waste Control and Treatment, by W. J. Jewell, H. R.
Davis, D. F. Johndrew, Jr., R. C. Loehr, W. Siderewicz, and R. R. Zall. EPA-
660/2-75-019, June 1975.
6. Aerated Lagoon Treatment of Food Processing Wastes, by K. A. Dostal. Water
Pollution Control Research Series 12060--03/68, March 1968.
7. Upgrading Lagoons. EPA Technology Transfer Seminar Publication, August 1973.
Some papers in the Proceedings of First, Second, Fourth, and following National
Symposia may be pertinent to land application.
14.10
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8. Waste Treatment, Upgrading Meat Packing Facilities to Reduce Pollution. EPA
Technology Transfer Seminar Publication, Oct. 1973.
9. Waste Treatment, Upgrading Poultry-Processing Facilities to Reduce Pollution.
EPA Technology Transfer Seminar Publication, July 1973.
10. Meatpacking Wastewater Treatment by Spray Runoff Irrigation, by J. L. Witherow
and M. L. Rowe. PNERL Working Paper No. 15, May 1975, Pacific Northwest Envi-
ronmental Research Laboratory, EPA, Corvallis, Ore.
11. Effluent Variability in the Meat-Packing and Poultry Processing Industries
J. F. Scaief. PNERL Working Paper No. 16, June 1975, Pacific Northwest Envi-
ronmental Research Laboratory, EPA, Corvallis, Ore.
12. Effectiveness of Spray Irrigation as a Method for the Disposal of Dairy Plant
Wastes, by G. W. Lawton, L. E. Engelbert, G. A. Rohlich, and N. Porges. Agri.
Exp. Sta. Res. Report No. 6, Univ. of Wisconsin, Madison, Wis.
13. The Development, Evaluation and Content of a Pilot Program in Dairy Utilization,
Dairy Waste Disposal and Whey Processing, by W. S. Arbuckle and L. F. Blanton.
Coop. Ext. Serv. and Dept. of Dairy Sci., Univ. of Maryland, College Park, Md.
14, An Evaluation of Cannery Waste Disposal by Overland Flow Spray Irrigation.
C. W. Thornthwaite Associates, Publications in Climatology Vol. 22, No. 2, Sept.
1969, Laboratory of Climatology, Elmer, N. J.
D. U. S. Army Corps of Engineers Reports
I. Assessment of the Effectiveness and Effects of Land Disposal Methodologies of
Wastewater Management, by C. H. Driver, B. F. Hrutfiord, D. E. Spyridakis, E. B.
Welch, and D. D. Wooldridge. Wastewater Management Report 72-1, Jan. 1972.
2. Wastewater Management by Disposal on the Land, S. C. Reed, Coordinator. Cold
Regions Research and Engineering Laboratory, Spec. Report 171, May 1972, Hanover,
N. H.
3. Reactions of Heavy Metals with Soils with Special Regard to Their Application in
Sewage Wastes, by G. W. Leeper, Nov. 1972.
4. Selected Chemical Characteristics of Soils, Forages, and Drainage Water from the
Sewage Farm Serving Melbourne, Australia, by R. D. Johnson, R. L. Jones, T. D.
Hinesly, and D. J. David, Jan. 1974.
5. Wastewater Treatment on Soils of Low Permeability, by R. E. Hoeppel, P. G. Hunt,
and T. B. Delaney, Jr. Misc. Paper Y-74-2, July 1974.
6. Land Application of astewate: The Fate of Viruses, Bacteria and Heavy Metals
at a Rapid Infiltration Site, by S. A. Schaub, E. P. Meier, J. R. Kolmer, and
C. A. Sorber. Report TR 7504, May 1975, U.S. Army Medical Bioengineering
Research and Development Laboratory, Fort Detrick, Frederick, Md.
7. An Evaluation of Land Treatment of Municipal Wastewater and Physical Siding of
Facility Installations, by W. J. Hartman, Jr. May 16, 1975.
14.11
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E. Miscellaneous Publications
1. Factors Involved in Land Application of Agricultural and Municipal Wastes.
Agri. Res. Serv., U.S. Dept. of Agriculture, Beltsville, Md., July 1974.
2. Treatment and Disposal of Wastewater Sludges, by P. A. Vesilind. Ann Arbor
Science Publishers, Ann Arbor, Mich., 1974.
3. Land Treatment and Disposal of Municipal and Industrial Wastewater, edited by
R. L. Sanks and T. Asano. Ann Arbor Science Publishers, Ann Arbor, Mich., 1976.
4. Soil Limitations for Disposal of Municipal Wastewaters, by I. F. Schneider and
A. E. Erickson. Research Report 195, Dept. of Crop and Soil Sciences, MSU.
5. Land Treatment of Wastewater in Southeastern Michigan, by B. G. Ellis, A. E.
Erickson, B. D. Knezek, R. J. Kunze, I. F. Schneider, E. P. Whiteside, A. R.
Wolcott, and R. L. Cook. June 1973, Dept. of Crop and Soil Sciences, MSU.
6. Impact of Wastewater on Soils, by B. G. Ellis, A. E. Erickson, B. D. Knezek,
and A. R. Wolcott. Inst. of Water Res. Tech. Report No. 30, Oct. 1972, Inst.
of Water Res., MSU.
7. Sampling and Analysis of Soils, Plants, Wastewaters, and Sludge — Suggested
Standardization and Methodology. North Central Regional Pub. 230, Dec. 1975,
Agri. Exp. Sta., MSU.
F. Publications to be Available Within 6-12 Months
1. Soils for Management and Utilization of Organic Wastes and Wastewaters. Pro-
ceedings of Symposium held March 11-13, 1975, at Tennessee Valley Authority,
Muscle Shoals, Ala. Published by Soil Science Society of America, Madison, Wis.
2. Land Application of Waste Materials. Proceedings of National Conference held
March 15-18, 1976, Des Moines, Iowa. Published by the Soil Conservation Society
of America, Ankeny, Iowa.
3. Land as a Waste Management Alternative. Eighth Annual Cornell University Waste
Management Conference held april 28-30, 1976, Rochester, N. Y. Published by
Cornell University, Ithaca, N. Y.
4. Virus Aspects of Applying Municipal Wastes to Land. Symposium held June 28-29,
1976, at University of Florida, Gainesville, Fla.
5. Utilizing Municipal Sewage Effluents and Sludges on Land for Agricultural Pro-
duction. Edited by L. W. Jacobs, 1976. To be published as a North Central
Regional Extension Bulletin.
6. Utilizing Sewage Sludges on Agricultural Soils. I. General Description and
Considerations; II. Factors for Determining Rates of Application, by L. W.
Jacobs, 1976. To be published as a two bulletin series, Coop. Ext. Serv.,
Mich. State Univ.
14.12
U. S. GOVERNMENT PRINTING OFFICE 1978 - 777-066/1121 Reg. 8
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