EPA-430/9-75-001
TECHNICAL BULLETIN
EVALUATION OF LAND
APPLICATION SYSTE
MARCH 1975
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Water Program Operations
Washington, D.C. 20460
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NOTE
Methods of estimating costs and evaluating the
costs effectiveness of land-application systems
are being developed in a separate document,
entitled, Technical Bulletin, Costs of Wastewater
Treatment by Land Application Systems, No.
EPA-430/9-75-003, which will become available
later in 1975
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EPA-430/9-75-001
TECHNICAL BULLETIN
EVALUATION OF LAND
EVALUATION CHECKLIST AND SUPPORTING COMMENTARY
f
MARCH 1975
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Water Program Operations
Washington, D. C. 20460
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ABSTRACT
Procedures are set forth to assist EPA personnel in evaluating treatment
systems that employ land application of municipal wastewater. In addition,
information and assistance is provided which may be of value to other federal,
state, and local agencies, the wastewater industry, consultants and designers.
However, it is not intended that the bulletin be used as a comprehensive
design manual.
The bulletin consists of an Evaluation Checklist and parallel background
information and is divided into three major parts dealing with: (1) facilities
plans, (2) design plans and specifications, and (3) operation and maintenance
manuals.
The focus of Part I is on the thorough evaluation of land-application alterna-
tives and the preparation of a detailed facilities plan. A number of interrelated
considerations are addressed, including: evaluation of potential sites,
evaluation of land-application alternatives, design considerations, and
environmental factors.
Procedures for evaluating design plans and specifications are described in
Part II, with emphasis being placed on agreement with the facilities plans
and the requirement for basing the review of the design on conditions present
at the particular site. Sample design criteria listings are included in the
appendix.
In Part III, extensive reference is made to the EPA publication Considerations
for Preparation of Operation and Maintenance Manuals. Special considerations
for land-application systems are presented with respect to operating procedures,
monitoring requirements, and impact control.
This report is submitted in partial fulfillment of Contract 68-01-0966 by
Metcalf & Eddy, Inc. , Western Regional Office, under the sponsorship of the
Environmental Protection Agency. Work was completed as of September 1974.
11
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TECHNICAL BULLETIN EPA-430/9-75-001
FOREWORD
This technical bulletin is published pursuant to certain sections of the Federal Water Pollution
Control Act Amendments of 1972, Public Law 92-500, enacted on October 18, 1972. The 1972
Amendments require the publication of information that will encourage waste treatment manage-
ment which results in facilities for (1) the recycling of potential sewage pollutants through the
production of agricultural, silvicultural, or aquacultural products; (2) the reclamation of waste-
water; and (3) the elimination of the discharge of pollutants. The Amendments also require the
consideration of alternative waste management techniques that provide the best practicable
waste treatment technology over the life of the treatment works.
The three principal waste management alternatives are (1) conventional treatment and discharge,
(2) conventional treatment and direct reuse, and (3) land treatment with discharges to surface
and/or groundwaters. Treatment by land application of wastewater is a viable waste manage-
ment alternative and is practiced successfully and extensively both in the United States and
throughout the world. This publication is concerned solely with land application for wastewater
treatment and is intended to encourage its use where it is cost-effective.
This bulletin is not a comprehensive design manual; primarily, it provides information and
program guidance to EPA Regional Offices for analyzing and evaluating municipal applications
for federal grants for the construction of publicly owned treatment works using land-application
methods. It also provides information and assistance to other federal agencies, to interstate
organizations, to state water pdLution control agencies, to the wastewater industry, and to
consultants and designers of land-application systems.
Admittedly, there is insufficient knowledge about certain aspects of the treatment of sewage
effluents by conventional secondary treatment as well as by land treatment to evaluate adequately
all of the ramifications of the potential health hazards by any method of treating wastewater.
EPA is proceeding with all deliberate speed, with its own resources and jointly with other insti-
tutions and agencies, to research these areas of insufficient knowledge. However, the success-
ful and extensive use of the land treatment technique over a long period of time throughout the
world justifies serious consideration of this method of treatment, even though, for example, it
is not possible at this time to specify acceptable levels of contaminants in the soil from land
application of wastewater. It must be demonstrated, however, that land treatment is the most
cost-effective alternative, is consistent with the environmental assessment, and in other
respects satisfies applicable tests.
As new aspects of land-application technology are developed through experience, additional
information will become available, and this publication will be revised. All users are encour-
aged to submit suggested revisions and pertinent information to the Director, Municipal Con-
struction Division, Office of Water Program Operations, U.S. Environmental Protection
Agency, Washington, D.C. 20460.
James L. Agee
Assistant Administrator for
Water and Hazardous Materials
111
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STATUTORY AND SUB-STATUTORY BASIS
The Federal Water Pollution Control Act Amendments of 1972 (Public Law
92-500), the legislative history of the Act, and the regulations which have
been issued in accordance with the provisions of the Act, provide the statu-
tory basis for consideration and funding of land-application systems in the
treatment of municipal wastewater.
LEGISLATION
The rationale and goals within which land-application systems are to be
considered are contained in the following sections of the Act:
Section 208 - Areawide Waste Treatment Management
Section 201 - Facilities Planning
Section 304 - Best Practicable Treatment Technology (BPT)
Section 212 - Cost Effectiveness Analysis
Concerning land application of municipal wastewater, the portions of these
sections that are most important are reproduced here:
Section 208
"SEC. 208. (a) For the purpose of encouraging and facilitating the
development and implementation of areawide waste treatment man-
agement plans
"(1) The Administrator,
after consultation with appropriate
Federal, State, and local authorities, shall by regulation publish
guidelines for the identification of those areas which, as a result
of urban-industrial concentrations or other factors, have sub-
stantial water quality control problems.
" (by(l) Xot later than one year after the date of designation of any
organization under subsection (a) of this section such organization
shall have in operation a continuing areawide waste treatment man-
agement planning process consistent with section 201 of this Act. Plans
prepared in accordance with this process shall contain alternatives for
waste treatment management, and be applicable to all wastes gen-
erated within the area involved. The initial plan prepared in accord-
ance witli such process shall be certified by the Governor and submitted
to the Administrator not later than two years after the planning proc-
ess is in operation.
' (2) Any plan prepared under such process shall include, but not be
limited to
"(A) the identification of treatment works necessary to meet
the anticipated municipal and industrial waste treatment needs of
the area over a twenty-year period, annually updated (including
fin analysis of alternative waste treatment systems), including
any requirements for the acquisition of land for treatment nur-
poses; the necessary waste water collection and urban storm water
runoff systems; and a program to provide the necessary financial
arrangements for the development of such treatment works;
IV
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"(B) the establishment of construction priorities for such treat-
ment works and time schedules for the initiation and completion
of all treatment works;
"(C) the establishment of a regulatory program to
"(i) implement the waste treatment management require-
ments of section 201 (c),
"(ii) regulate the location, modification, and construction
of any facilities within such area which may result in any
discharge in such area, and
"(iii) assure that any industrial or commercial wastes dis-
charged into any treatment works in such area meet applicable
pretreatment requirements;
" (D) the identification of those agencies necessary to construct,
operate, and maintain all facilities required by the plan and
otherwise to carry out the plan;
"(E) the identification of the measures necessary to carry out
the plan (including financing), the period of time necessary to
carry out the plan, the costs of carrying out the plan within such
time, and the economic, social, and environmental impact of
carrying out the plan within such time;
"(F) a process to (i) identify, if appropriate, agriculturally
and silviculturally related nonpoint sources of pollution, includ-
ing runoff from manure disposal areas, and from land used for
livestock and crop production, and (ii) set forth procedures
and methods (including land use requirements) to control to the
extent feasible such sources;
"(K) a process to control the disposal of pollutants on land or
in subsurface excavations within such urea to protect ground nnd
surfacci water quality.
Section 201
"SEC. 201. (a) It is the purpose of this title to require and to assist
the development and implementation of waste treatment management
plans and practices which will achieve the goals of this Act.
"(b) Waste treatment management plans and practices shall provide
for the application of the best practicable waste treatment technology
before any discharge into receiving waters, including reclaiming and
recycling of water, and confined disposal of pollutants so they wfll not
migrate to cause water or other environmental pollution and shall pro-
vide for consideration of advanced waste treatment techniques.
" (c) To the extent practicable, waste treatment management shall be
on an area wide basis and provide control or treatment of all point and
nonpoint sources of pollution, including in place or accumulated pol-
lution sources.
"(d) The Administrator shall encourage waste treatment manage-
ment which results in the construction of revenue producing facilities
providing for
:'(1) the recycling of potential sewage pollutants through the
production of agriculture, silviculture, or aquaculture products, or
any combination thereof;
"(2) the confined and contained disposal of pollutants not
recycled;
''(3) the reclamation of wastewater; and
;'(4) the, ultimate disposal of sludge in a manner that will not
result in environmental hazards.
"(e) The Administrator shall encourage waste treatment manage-
ment which results in integrating facilities for sewage treatment and
recycling with facilities to treat, dispose of, or utilize other industrial
and municipal wastes, including but not limited to solid waste and
waste heat and thermal discharges. Such integrated facilities shall be
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designed and operated to produce revenues in excess of capital and
operation and maintenance costs and such revenues shall be used by
the designated regional management agency to aid in financing other
environmental improvement programs.
'(f) The Administrator shall encourage waste treatment manage-
ment which combines 'open space' and recreational considerations with
such management.
"(g)(l) The Administrator is authorized to make grants to any
State, municipality, or inter municipal or interstate agency for the
construction of publicly owned treatment works.
"(2) The Administrator shall not make grants from funds author-
ised for any fiscal year beginning after June 30, 1974, to any State,
municipality, or intermunicipal or interstate agency for the erection,
building, acquisition, alteration, remodeling, improvement, or exten-
sion of treatment works unless the grant applicant has satisfactorily
demonstrated to the Administrator that
" (A) alternative waste management techniques have been stud-
ied and evaluated and the works proposed for grant assistance
will provide for the application of the best practicable waste
treatment technology over the life of the works consistent with the
purposes of this title; and
"(B) as appropriate, the works proposed for grant assistance
will take into account and allow to the extent practicable the
application of technology at a later date which will provide for
the reclaiming or recycling of water or otherwise eliminate the
discharge of pollutants.
Section 304
Section 212
'(d)(i>) The Administrator, after consultation with appropriate Fed-
fi-fll ;;nd State Hgencies ;>.nd other interested persons, shall publish
within nine months f\ft<-r tho date of enactment of this title (and from
time to time, thereafter) information on alternative waste, treatment
manafioment techniques isncl systems available to implement section
201 of this Act,.
"SEC. 212. As used in this title
"(1) The term 'construction' means any one or more of the follow-
ing : preliminary planning to determine the feasibility of treatment
works, engineering, architectural, legal, fiscal, or economic investiga-
tions or studies, surveys, designs, plans, working drawings, specifica-
tions, procedures, or other necessary actions, erection, building,
acquisition, alteration, remodeling, improvement, or extension of
treatment works, or the inspection or supervision of any of the
foregoing items.
''(2) (A) The term 'treatment works' means any devices and systems
used in the storage, treatment, recycling, and reclamation of municipal
sewage or industrial wastes of a liquid nature to implement section
201 of this Act, or necessary to recycle or reuse water at the most eco-
nomical cost over the estimated life of the works, including intercept-
ing seweis, outfall sewers, sewage collection systems, pumping, power,
and other equipment, and their appurtenances; extensions, improve-
ments, remodeling, additions, and alterations thereof; elements essen-
tial to provide a reliable recycled supply such as standby treatment
units and clear well facilities; and any works, including site acquisition
of the land that will be an integral part of the treatment process or is
used for ultimate disposal of residues resulting from such treatment.
"(B) In addition to the definition contained in subparagraph (A)
of this paragraph, 'treatment works' means any other method or sys-
tem for preventing, abating, reducing, storing, treating, separating,
or disposing of municipal waste, including storm water runoff, or
industrial waste, including waste in combined storm water and sani-
tary sewer systems. Any application for construction grants which
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includes wholly or in part such methods or systems shall, in accordance
with guidelines published by the Administrator pursuant to subpara-
graph (C) of this paragraph, contain adequate data and analysis
demonstrating such proposal to be, over the life of such works, the
most, cost efficient alternative to comply with sections 301 or 302 of
this Act, or the requirements of section 201 of this Act.
REGULATIONS
In addition to the legislation itself, regulations have been issued that
pertain to land application. The following regulations represent a portion
of the EPA program to implement requirements of Title II of the Act.
Areawide Waste Treatment Management (Section 208)
The regulatory basis for Section 208 areawide waste treatment management
planning pertaining to land-application systems is contained in 40 CFR 35,
subpart F, published in the Federal Register May 13, 1974. The planning
for areawide waste treatment management consists of two interrelated con-
siderations: analysis and implementation. Analysis serves to identify
important factors. Implementation involves practical aspects for realizing
alternatives that can improve water quality. Under the Section 208 Interim
Grant Regulation, implementation alternatives must consider all policy
variables that can be adjusted to produce improvement of water quality.
As one policy variable, land-application systems can play a significant
role in development of areawide planning management alternatives.
Disposition of residual wastes and control of disposal of pollutants must
be considered in formulation of areawide waste treatment management
plans. Again, the consideration of land-application systems is a means
for achieving this.
Grants for Construction of Treatment Works (Section 201)
The Title n regulations set forth, in general, the procedures and condi-
tions for award of grant assistance. Section 917 of these regulations
specifies the facilities planning requirements, and Appendix A of these
regulations gives the cost-effectiveness analysis guidelines. Both guide-
lines include mention of land application as alternative waste management
systems.
Guidance for Facilities Planning - The publication, Guidance for Facilities
Planning, March 1974, provides supplemental guidance and information
regarding planning and evaluation of various alternatives for publicly-
owned waste treatment works. Basically, facilities planning includes
(1) a statement of the problems; (2) an inventory of existing systems;
(3) a projection of future conditions; (4) setting of goals and objectives;
(5) an evaluation of alternatives, which may variously include land treat-
ment or reuse of wastewater, flow reduction measures (including the
correction of excessive infiltration/flows, alternative system configura-
tions , phased development of facilities, or improvements in operation and
maintenance) to meet those goals and objectives; and (6) an assessment of
the environmental impacts of the alternatives. Such planning provides for
cost-effective and environmentally sound treatment works which will meet
applicable effluent limitations.
vii
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Cost-Effectiveness Analysis Guidelines - Regulations for the cost-effectiveness
analysis (40 CFR 35 Appendix A), published in the Federal Register on
September 10, 1973, provide information for determining the most cost-
effective waste treatment management system or the most cost-effective
component part of any waste treatment management system, including
the identification, selection, and screening of alternative waste management
systems. These alternatives should include systems discharging to receiving
waters, systems using land or subsurface disposal techniques, and systems
employing the reuse of wastewater. A complete text of the guidelines is
included herein as Appendix G.
Secondary Treatment Information (Section 304 (d) (1))
Information on secondary treatment (40CFR 133) was published in the
Federal Register on August 17, 1973. Land-application systems with point
source discharges must comply with these minimum standards.
Alternative Waste Management Techniques for Best Practicable Waste
Treatment (Section 304 (d) (2))
This publication provides information on best practicable treatment technology
(BPT) and contains information and criteria for waste management techniques
involving land application. The proposed BPT criteria for a land-application
system where the effluent results in permanent groundwater are based on
protection of groundwater for drinking water supply purposes. The proposed
version, dated March 1974, is now being finalized.
viii
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CONTENTS
Part Page
ABSTRACT ii
FOREWORD iii
STATUTORY AND SUB-STATUTORY BASIS iv
FIGURES xi
TABLES xi
PARTICIPANTS xii
INTRODUCTION 1
EVALUATION CHECKLIST
Part I - Facilities Plan 5
Part II - Design Plans and Specifications 15
Part ni - Operation and Maintenance Manual 19
I WASTEWATER MANAGEMENT PLAN
A. Project Objectives 21
B. Evaluation of Wastewater Characteristics 23
C. Evaluation of Potential Sites 31
D. Consideration of Land-Application Alternatives 41
E. Design Considerations 51
F. Environmental Assessment 83
G. Implementation Program 89
II DESIGN PLANS AND SPECIFICATIONS
A. Agreement with Facilities Plan 93
B. Site Characteristics 95
C. Design Criteria 101
D. Expected Treatment Performance 113
III OPERATION AND MAINTENANCE MANUAL
A. EPA Considerations for Preparation of
Operation and Maintenance Manuals 117
B. Operating Procedures 123
C. Monitoring 127
D. Impact Control 131
IX
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CONTENTS (Continued)
Part Page
IV APPENDIXES
A. References 133
B. Selected Annotated Bibliography 149
C. Glossary of Terms, Abbreviations, Symbols,
and Conversion Factors 155
D. Typical Summary of Design Criteria for
Land-Application Systems 163
E. Proposed California Regulations 167
F. Sources of Data 179
G. Cost-Effectiveness Analysis Guidelines 181
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FIGURES
No. Page
1 Planning Sequence for Land-Application Alternatives 2
2 Typical Frequency Analysis for Total Annual Precipitation 33
3 Methods of Land Application 42
4 Irrigation Techniques 46
TABLES
1 General Guidelines for Salinity in Irrigation Water 25
2 Water-Quality Guidelines 27
3 Recommended Maximum Concentrations of Trace
Elements in Irrigation Waters 29
4 Comparison of Irrigation, Overland Flow, and
Infiltration-Percolation of Municipal Wastewater 41
5 Water Balance for Example No. 1 54
6 Typical Values of Crop Uptakes of Nitrogen 57
7 Yield Decrement to be Expected for Field Crops Due
to Salinity of Irrigation Water When Common Surface
Methods are Used 68
8 Yield Decrement to be Expected for Forage Crops
Due to Salinity of Irrigation Water 69
9 Calculation of Storage Volume Requirements per Acre
of Field Area for Example No. 3 72
10 Estimated Annual Manhour Requirements for Land-
Application Alternatives with a Design Flow of 1. 0 mgd 76
11 Suggested Service Life for Components of an
Irrigation System 79
12 Removal Efficiencies of Major Constituents for
Municipal Land-Application Systems 113
D-l Irrigation 163
D-2 Infiltration-Percolation 164
D-3 Overland Flow 165
XI
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PARTICIPANTS
EPA PROJECT OFFICER: Mr. Belford L. Seabrook
TECHNICAL REVIEW: Inter-Agency Soil Treatment Systems Work Group
EPA Members
RichardE. Thomas, OR&D (Chairman)
Kerr Water Research Center, Ada, Oklahoma
Belford L. Seabrook, Office of Water Program Operations,
Washington, B.C.
Darwin R. Wright, OR&D
Municipal Pollution Control Division, Washington, D.C.
G. Kenneth Dotson, National Environmental Research Center
Cincinnati, Ohio
Stuart C. Peterson, Region I, Boston
Daniel J. Kraft, Region n, New York
W. L. Carter, J. Potosnak, Region HI, Philadelphia
J. David Ariail, Region IV, Atlanta
Eugene I. Chaiken, Region V, Chicago
Jerry W. Smith and Richard G. Hoppers, Region VI, Dallas
Jay Zimmerman, Region Vn, Kansas City
R. Hagen and Roger Dean, Region VIII, Denver
Lewis G. Porteous, Region DC, San Francisco
Norman Sievertson, Region X, Seattle
Other Members
Charles E. Pound Eliot Epstein, USDA
Metcalf & Eddy, Inc. Beltsville, Maryland
Palo Alto, California
George L. Braude, FDA
Sherwood C. Reed, CRREL Washington, D.C.
U.S. Army Corps of Engineers
Hanover, New Hampshire Jack C. Taylor, FDA
Rockville, Maryland
William E. Larson, USDA
University of Minnesota
St. Paul, Minnesota
CONTRACTOR: Metcalf & Eddy, Inc., Palo Alto, California
Supervision: Franklin L. Burton, Chief Engineer
Authors: Charles E. Pound, Project Manager
Ronald W. Crites, Project Engineer
Douglas A. Griffes
Consultant: Dr. George Tchobanoglous, University of California,
Davis
xii
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INTRODUCTION
The purpose of this publication is to suggest procedures for the evaluation and
review of municipal wastewater treatment system alternatives that employ
the land application of effluent. It is not intended to be used as a design guide.
An Evaluation Checklist and background information are provided, and procedures
are given for evaluating alternatives dealing with irrigation, infiltration-
percolation, overland flow, or combinations of these land-application approaches.
Systems involving injection wells, sealed evaporation ponds, or septic-tank leach
fields for wastewater disposal are excluded, as are systems in which sludge is
applied to the land. .
To properly evaluate each step involved in planning, design, and operation of soil
systems, the Evaluation Checklist is divided into three major parts dealing with:
(1) facilities plans, (2) design plans and specifications, and (3) operation and
maintenance manuals. Organization of the text containing the background informa-
tion parallels the Evaluation Checklist and is keyed to it by appropriate symbols
in the headings.
FACILITIES PLAN (PART I)
The recommended wastewater management plan should be based on the apparent
best alternative as derived from a detailed evaluation of the various treatment
alternatives. These alternatives should include systems using land-application
as required in the cost-effectiveness analysis guidelines (40 CFR 35, Appendix A)
and the best practicable treatment (BPT) document [3] . When BPT is referred
to throughout this bulletin, it refers to reference [3], which was in proposed form
at the time of publication, and any future revisions to that document.
The focus of Part I is on the thorough evaluation of land-application alternatives,
and the preparation of a detailed facilities plan. It should be used in conjunction
with Guidance for Facilities Planning [62]. The result should be definitive
regarding design criteria, so that design plans and specifications may easily
follow. An attempt has been made to avoid restrictive or dogmatic standards
because most design criteria are site-specific. Instead, important considerations
are discussed and reasonable ranges suggested. Key elements to consider are:
(1) Did the engineer consider appropriate land-application approaches or combina-
tions and modifications thereof, and (2) What was the basis for screening the
land-application alternatives?
Emphasis is placed on long-range planning and environmental factors. Are
the alternatives compatible with local and regional planning goals and objectives?
With regard to environmental factors, a careful assessment must be made of
the completeness and detail of the investigation and the overall design considera-
tions provided to minimize any adverse impacts.
The normal sequence and interrelationship of steps in the preparation of a
wastewater management plan are presented in Figure 1. For the most part,
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EVALUATION OF
IASTEIATER
CHARACTERISTICS
PREAKPLICATION
TREATMENT
DESI9N
EVALUATION OF
POTENTIAL SITES
LAND APPLICATION
ALTERNATIVES
SITE
CHARACTERISTICS
DESIGN
CONSIDERATIONS
OVERLOAD
ENVIRONMENTAL
ASSESSMENT
ADVERSE
IMPACTS
REVIEW AND
REEVALUATE
PLAN SELECTION
IMPLEMENTATION
PROGRAM
Figure 1. Planning sequence for land-application alternatives
these steps correspond directly in title and sequence to the sections in Part I.
ig process involves repeating the sequence of steps until the implex
v%f\ w\ -i in -Pi *»*» I -i rr s\n
these steps correspond directly in title and sequence t
The planning process involves repeating the sequence
tation program is finalized.
DESIGN PLANS AND SPECIFICATIONS (PART II)
lemen-
The design plans and specifications should be a logical extension of the facilities
plan. Details of the wastewater management plan are presented in the plans and
specifications for implementation and construction purposes. A complete listing
of site characteristics and major design criteria should accompany or be included
in the plans and specifications for ease in evaluation. Important considerations
in design are discussed in Part II with stress placed on the continuity between
recommendations in the facilities plan and features of the design.
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OPERATION AND MAINTENANCE MANUAL (PART III)
The Operation and Maintenance Manual is a tool of fundamental importance for
management of the treatment system. The design concepts should be clearly
explained and procedures for operating and maintaining the facilities must be
delineated. The manual is intended to be a guide for the operators of the treat-
ment facilities and will help to ensure that they understand the key design features
and the objectives for which the system was designed. The manual should include
maintenance schedules, monitoring programs, and recommendations for man-
power utilization. Additionally, potential problem areas, symptoms of process
malfunction, and methods of control of adverse impacts should be described.
Special considerations, such as agricultural practices for irrigation systems,
should also be included.
Extensive reference is made to Considerations for the Preparation of Operation
and Maintenance Manuals [61] throughout Part III, and Section A is devoted en-
tirely to a discussion of the use of this reference. In the remaining three
sections, additional considerations particular to operation and maintenance
manuals for land-application systems are presented.
CONSIDERATION OF SYSTEM SIZE
The scope of the Evaluation Checklist is aimed at moderate-to-large sized land-
application systems. The extent to which planning and design of small systems
(say 0. 5 mgd or less) should adhere to all points in the checklist is left to the
discretion of the evaluator.
SOURCES OF DATA
Throughout this report, major sources of information on each subject are cited
for easy references. These sources should not be viewed as the only ones avail -
able; when appropriate, other interested agencies, such as the USDA and FDA,
or local government, university, or independent consultants should be sought out
for pertinent data. References cited by bracketed numbers in the text are listed
in alphabetical order in Appendix A. A short annotated bibliography of the
major reports on land application of wastewater is included as Appendix B.
PUBLIC ACCEPTANCE
In many cases, public acceptance may be the primary limiting factor in the
implementation of land-application projects. At each step in the review process,
the evaluator should ensure that areas of public concern have been identified,
and that these concerns are reflected in the facilities plan, plans and specifica-
tions, and operation and maintenance manual.
One source of public concern is often the relative uncertainty over various health
effects. With regard to this concern, the evaluator should pay particular atten-
tion to such items as the degree of preapplication treatment, types of crops that
may be grown, and the degree of public contact with the effluent.
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EVALUATION CHECKLIST FOR TREATMENT
ALTERNATIVES EMPLOYING LAND APPLICATION OF WASTEWATER
The purpose of this checklist is to provide reviewers with the pertinent factors
to be considered in the planning, design, and operation of systems employing
land application of municipal effluents. The format of the checklist has been
selected to enable the reviewer to enter a check mark or comment to the right
of each item. Items are arranged so that the more important ones appear first.
Those items for which a dashed checkline appears are desirable but not essential
considerations. The notation and headings used are generally the same as those
used in the background information text.
Part I FACILITIES PLAN
A. Project Objectives
Objectives and goals relevant to water quality,
protection of groundwater aquifer, the need for
augmenting existing water resources, and any
other desired effects should be considered
initially.
B. Evaluation of Wastewater Characteristics
1. Flowrates
Present, projected, and peak flow
2. Existing treatment
a. Description
b. Adequacy for intended project
3. Existing effluent disposal facilities
a. Description
b. Consideration of water rights
4. Composition of effluent to be applied
a. Total dissolved solids
b. Suspended solids
c. Organic matter (BOD, COD, TOC)
d. Nitrogen forms (all)
e. Phosphorus
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I-B.4. (continued)
f. Inorganic ions
(1) Heavy metals and trace elements
(2) Exchangeable cations (SAR)
(3) Boron
g. Bacteriological quality
h. Projected changes in characteristics
i. Are industrial wastewater components
considered?
j. BPT constituents
C. Evaluation of Potential Sites
All potential sites should be considered on the
basis of the criteria listed in this section, and
should be reevaluated in the light of design
considerations and environmental assessment.
1. General description
a. Location
(1) Distance from collection area or
treatment plant
(2) Elevation relative to collection
area
b. Compatibility with overall land-
use plan
(1) Current use
(2) Proposed future use
(3) Zoning and adjacent land use
(4) Proximity to current and
planned developed areas
(5) Is there room for future
expansion?
c. Proximity to surface water
d. Number and size of available land
parcels
2. Description of environmental characteristics
a. Climate
(1) Precipitation analysis and seasonal
distribution
(2) Storm intensities
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I-C.2.a. (continued)
(3) Temperature, with seasonal
variations
(4) Evapotranspiration
(5) Wind velocities and direction
b. Topography
(1) Ground slope
(2) Description of adjacent land
(3) Erosion potential
(4) Flood potential
(5) Extent of clearing and field
preparation necessary
c. Soil characteristics
(1) Type and description
(2) Infiltration and percolation potential
(3) Soil profile
(4) Evaluation by soil specialists
d. Geologic formations
(1) Type and description
(2) Evaluation by geologist
(3) Depth of formations
(4) Earthquake potential
e. Groundwater
(1) Depth to groundwater
(2) Groundwater flow
(3) Depth and extent of any perched
water
(4) Quality compared to requirements
(5) Current and planned use
(6) Location of existing wells
(a) On site
(b) Adjacent to site
f. Receiving water (other than groundwater)
(1) Type of body
-------
I-C.2.L (continued)
(2) Current use
(3) Existing quality
(4) Is it water-quality limited?
(5) Is it effluent limited?
(6) Water rights
3. Methods of land acquisition or control
a. Purchase
b. Lease
c. Purchase and lease back to farmer
d. Contract with users
e. Other
D. Consideration of Land-Application Alternatives
Based on the project objectives and characteristics
of the selected potential sites, appropriate methods
of land application should be considered.
I. Irrigation
a. Purpose
(1) Optimization of crop yields
(2) Maximization of effluent application
(3) Landscape irrigation
b. Application techniques
(1) Spraying
(2) Ridge and furrow
(3) Flooding
2. Infiltration-percolation
a. Purpose
(1) Groundwater recharge
(2) Pumped withdrawal or underdrains
(3) Interception by surface water
b. Application techniques
(1) Spreading
(2) Spraying
-------
I-D. (continued)
3. Overland flow (spray-runoff)
a. Purpose
(1) Discharge to surface waters
(2) Reuse of collected runoff
b. Application techniques
(1) Spraying
(2) Flooding
4. Combinations of treatment techniques
a. Combinations of land-application
techniques at the same or different
sites
b. Combinations of land-application
with in-plant treatment and receiving
water discharge
5. Compatibility with site characteristics
E. Design Considerations
1. Loading rates
a. Liquid loading/water balance
(1) Design precipitation
(2) Effluent application
(3) Evapotranspiration
(4) Percolation
(5) Runoff (for overland flow systems)
b. Nitrogen mass balance
(1) Total annual load
(2) Total annual crop uptake
(3) Denitrification and volatilization
(4) Addition to groundwater or
surface water
c. Phosphorus mass balance
d. Organic loading rate (BOD)
(1) Daily loading
(2) Resting-drying period for oxidation
e. Loadings of other constituents
-------
I-E. (continued)
2. Land requirements
a. Field area requirement
b. Buffer zone allowance
c. Land for storage
d. Land for buildings, roads and ditches
e. Land for future expansion or
emergencies
3. Crop selection
a. Relationship to critical loading
parameter
b. Public health regulations
c. Ease of cultivation and harvesting
d. Length of growing season
e. Landscape requirements
f. Forestland
4. Storage requirements
a. Related to length of operating
season and climate
b. For system backup
c. For flow equalization
d. Secondary uses of stored wastewater
5. Preapplication treatment requirements
a. Public health considerations
b. Relationship to loading rate
c. Relationship to effectiveness of
physical equipment
6. Management considerations
a. System control and maintenance
b. Manpower requirements
c. Monitoring requirements
d. Emergency procedures
7. Cost-effectiveness analysis
a. Capital cost considerations
(1) Construction or other cost index
(2) Service life of equipment
(3) Land cost
10
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I-E.7. (continued)
b. Fixed annual costs
(1) Labor
(2) Maintenance
(3) Monitoring
c. Flow-related annual costs
(1) Power
(2) Crop sale or disposal
d. Nonmonetary factors
8. Flexibility of alternative
a. With regard to changes in treatment
requirements
b. With regard to changes in wastewater
characteristics
c. For ease of expansion
d. With regard to changing land
utilization
e. With regard to technological advances
9. Reliability
a. To meet or exceed discharge
requirements
b. Failure rate due to operational
breakdown
c. Vulnerability to natural disasters
d. Adequate supply of required resources
e. Factors -of-safety
1 0. Best practicable waste treatment technology (BPT)
a. Requirements for groundwater quality
b. Requirements for treatment and discharge
F. Environmental Assessment
The impact of the project on the environment,
including public health, social, and economic
aspects must be assessed for each land-
application alternative.
1. Environmental impact
a. On soil and vegetation
b. On groundwater
(1) Quality
11
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I-F.l.b. (continued)
(2) Levels and flow direction
c. On surface water
(1) Quality
(2) Influence on flow
d. On animal and insect life
e. On air quality
f. On local climate
2. Public health effects
a. Groundwater quality
b. Insects and rodents
c. Runoff from site
d. Aerosols
e. Contamination of crops
3. Social impact
a. Relocation of residents
b. Effects on greenbelts and open space
c. Effect on recreational activities
d. Effect on community growth
4. Economic impact
a. On overall local economy
b. Tax considerations (land)
c. Conservation of resources and energy
G. Implementation Program
The ability to implement the project must be
assessed in light of the overall impact, the
effectiveness of the tentative design, and with
regard to public opinion.
1. Public information program
a. Approaches to public presentation
(1) Local officials
(2) Public hearings
(3) Mass media
12
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I-G.I. a. (continued)
(4) Local residents and land owners
(5) Communication with special-
interest groups
b. Public opinion
(1) Engineer's response
(2) Review of problem areas
2. Legal considerations
3. Reevaluation of ability to implement project
4. Implementation schedule
a. Construction schedule
b. Long-range management plan
13
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EVALUATION CHECKLIST FOR TREATMENT SYSTEMS
EMPLOYING LAND APPLICATION OF WASTEWATER
Part H DESIGN PLANS AND SPECIFICATIONS
The purpose of this part is to ensure completeness of the engineering design
considerations and to assess the compatibility of the design with the facilities
plan.
A. Agreement with Facilities Plan
1. Modifications
a. Have modifications affected other
design criteria?
b. Is supporting material included?
c. Were pilot studies recommended in
the report?
2. Reevaluation of facilities plan
a. With regard to changes in the interim
period
(1) In federal or state regulations
(2) In basin planning
b. With regard to findings of pilot
studies
B. Site Characteristics
1. Topography
a. Site plan
b. Effects of adjacent topography
(1) Will it add storm runoff?
(2) Will it back up water onto site ?
(3) Will -it provide relief for drainage ?
c. Erosion-prevention considerations
d. Earthwork required
(1) For field preparation
(2) For transmission, storage, and roads
15
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n-B.l. (continued)
e. Method of disposal of trees, brush,
and debris
2. Soil
a. Soil maps
b. Soil profiles
(1) Location
(2) Physical and chemical analysis
3. Geohydrology
a. Map of important geologic formations
b. Analysis of geologic discontinuities
c. Groundwater analysis
C. Design Criteria
1. Climatic factors
a. Precipitation
(1) Total annual precipitation
(2) Record maximum and minimum
annual
(3) Monthly distribution
(4) Storm intensities
(5) Effects of snow
b. Temperature
(1) Monthly or seasonal averages and
variation
(2) Length of growing season
(3) Period of freezing conditions
c. Wind
2. Infiltration and percolation rates
a. Design rates
b. Basis of determination
(1) Agriculture extension service or
soil specialists
(2) From soil borings and profiles
(3) From analysis of SCS soil surveys
16
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II-C.2.b. (continued)
(4) From farming experience
(5) From results of pilot studies
3. Loading rates
a. List of loading rates
b. Critical loading rate
4. Land requirements
a. Application area
(1) Wetted area
(2) Field area
b. For buffer zones
c. For storage
d. For preapplication treatment, buildings,
and roads
e. For future or emergency needs
5. Application rates and cycle
a. Annual liquid loading rate
b. Length of operating season
c. Application cycle
(I) Application period and rate
(2) Weekly application rate
(3) Resting or drying period
(4) Rotation of plots or basins
6. Crops/vegetation
a. Compatibility with site characteristics
and loading rates
b. Nutrient uptake
c. Cultivation and harvesting requirements
d. Suitability for meeting health criteria
7. System components
a. Preapplication treatment facilities
b. Transmission facilities
c. Storage facilities
d. Distribution system
-------
II-C.7. (continued)
e. Recovery system
f. Monitoring system
8. Design flexibility
a. Provisions for system expansion
b. Provisions for system modification
c. Interconnections and partial isolation
9. Reliability
a. Factors-of-safety
b. Backup systems
c. Contingency provisions
(1) Equipment or unit failure
(2) Natural disasters
(3) Severe weather
(4) Unexpected peak flows
D. Expected Treatment Performance
1. Removal efficiencies for major
constituents
2. Remaining concentrations in renovated
water
18
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EVALUATION CHECKLIST FOR TREATMENT SYSTEMS
EMPLOYING LAND APPLICATION OF WASTEWATER
Part III OPERATION AND MAINTENANCE MANUAL
The operation and maintenance manual should be prepared in accordance with
EPA guidelines that deal specifically with the subject; however, special consider-
ations for land-application systems are presented.
A. EPA Considerations for Preparation of Operation
and Maintenance Manuals
1. Introduction
2. Permits and standards
3. Description, operation, and control of
wastewater treatment facilities
4. Description, operation, and control of
sludge-handling facilities
5. Personnel
6. Laboratory testing
7. Records
8. Maintenance
9. Emergency operating and response program
10. Safety
11. Utilities
12. Electrical system
13. Appendixes
B. Operating Procedures
1. Application of effluent
a. Distribution system
b. Schedule of application
2. Agricultural practices
a. Purpose of crop
b. Description of crop requirements
c. Planting, cultivation, and harvesting
19
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in-B. (continued)
3. Recovery of renovated water
4. Storage
5. Special problems and emergency
conditions
C. Monitoring
1. Parameters to be monitored
2. Monitoring procedures
a. Location of sampling points
b. Schedule of sampling
«
3. Interpretation of results
4. Surveillance and reporting
D. Impact Control
I. Description of possible adverse effects
a. Environmental
b. Public health
c. Social
d. Economic
2. Indexes of critical effects
3. Methods of control
4. Methods of remedial action
20
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PART I
WASTE WATER
MANAGEMENT PLAN
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Section A
PROJECT OBJECTIVES
Proper evaluation of land application of wastewater as a treatment alternative
requires that a clear set of project goals and objectives be established. The
success of the project will depend to a large degree upon the careful formulation
of these objectives. Some of the major questions that should be answered are:
What are the immediate and long-term water-quality objectives?
Is there potential for meeting the BPT requirements for protecting
groundwater?
Is there a need to consider wastewater as a means of augmenting exist-
ing water resources?
What are the areal plans and policies for land use?
Is there a need to minimize land requirements?
Is there a need to minimize use of resources (or energy)?
Immediate and long-term water-quality objectives should be determined for both
surface waters and groundwater in order that treatment requirements may be
assessed for potential systems. These objectives should be related to both the
basin water quality management plan (40 CFR 131), and the areawide waste
treatment plan (40 CFR 35.1050). Critical parameters and constituents, and
special water-quality problems of a particular area should be identified.
The BPT requirements [3] establish a need to protect all groundwater to
some level. As stated in the BPT document, "land application practices should
not further degrade the air, land, or navigable waters; should not interfere
with the attainment or maintenance of public health, state, or local land use
policies; and should insure the protection of public water supplies, agricultural
and industrial water uses, propagation of a balanced population of aquatic and
land flora and fuana, and recreational activities in the area." The water-quality
criteria for drinking water supplies are the most thoroughly defined of the above
objectives, and may often be adequate alone. However, there may be instances
where more stringent quality criteria may be required to protect beneficial uses
other than drinking water. A determination should be made of the potential for
meeting the BPT requirements for protecting groundwater based on the effluent
quality to be applied (I-B.4), the site and groundwater characteristics (I-C.2),
the type of land-application system (I-D), and design loading rates (I-E.l).
The overall water-use plan should be evaluated to determine the value of using
wastewater to augment existing water resources. For many areas, the reuse of
wastewater may offer new water-use possibilities, or may relieve requirements
for fresh water. Irrigation, groundwater recharge, and water-based recreation
are water-use possibilities that could be investigated.
21
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Land-use trends and plans should be evaluated to determine if a land-application
system would be compatible with other land uses, and if land exists that may
benefit from land application of effluent. The need for land for other purposes,
such as industrial, commercial, or residential expansion should be determined,
as should beneficial effects, such as development of agricultural land, parks, or
greenbelts.
The availability of land may be limited or land costs may be high in many
densely populated or developed areas. The need to minimize land requirements
will then become an important consideration in which high-rate application sys-
tems, such as infiltration-percolation and overland flow, are emphasized.
Resources necessary for various treatment alternatives that must be conserved
should be noted. Materials and chemicals required for certain treatment pro-
cesses, and energy are among those resources that may be limited in supply and
must be conserved.
22
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Section B
EVALUATION OF WASTEWATER CHARACTERISTICS
A necessary preliminary step when planning for a land-application system, as
with any other treatment system, is a detailed evaluation of the wastewater
characteristics. The characteristics will, to some degree, affect the treatment
method whether irrigation, overland flow, or infiltration-percolation and will
directly affect the system design. Evaluation of the wastewater characteristics
should include: (1) flowrates, (2) quality changes resulting from existing
treatment, (3) existing effluent disposal practices, and (4) composition of
effluent.
B. 1. FLOWRATES
The quantity of effluent to be treated by the land-application system should be
estimated as closely as possible. Clearly, the success of the project will de-
pend to a large degree on the accuracy of estimating flowrates. Flowrates
which should be estimated include:
Present or initial flow
Present sustained peak flow
Projected future flow
Projected sustained peak flow
Instantaneous peaks (less than 1 hour in duration) will have little effect on most
designs; however, sustained peaks for 3 or 4 hours or more may require special
design features in pumping, preapplication treatment, or storage. In some cases,
industrial flows, such as from canneries, may result in seasonal peaks lasting
for several months. In such cases, special provisions must be made, such as
using additional land.
Stormwater must be considered for combined sewer systems and an infiltration/
inflow analysis must be conducted on sanitary sewer systems to determine the
extent of groundwater or stormwater infiltration. The EPA publication on urban
stormwater management and technology [79] will be a useful reference for as-
sessing the magnitude of stormwater flows and the problems that may be en-
countered. Infiltration/inflow analysis should be conducted in accordance with
Federal Regulation 35.927 [59] and the EPA publication entitled, Guidance for
Sewer System Evaluation [63] . Where large sustained peaking factors exist
as a result of infiltration/inflow or industrial/commercial activity, considera-
tion may be given to storage for flow equalization.
23
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B. 2. EXISTING TREATMENT
Where land application is to be used, varying degrees of preapplication treat-
ment, ranging from primary screening to secondary treatment with advanced
treatment for certain constituents may be required. The degree of preapplica-
tion treatment necessary will depend upon a number of factors, including the
land-application method, the effluent limitations established, the groundwater-
quality criteria established in the BPT document [_3\, and the design features
of the system (see I-E. 5). In most cases where land application is to be an
additional step, existing treatment facilities may partially fulfill preapplica-
tion treatment requirements. The existing facilities should be evaluated for
capacity, degree of treatment, and adaptability for land-application alternatives
B. 3. EXISTING EFFLUENT DISPOSAL FACILITIES
Existing effluent disposal practices should be described as they relate to the
overall basin hydrology. Existing and proposed effluent or water-quality stand-
ards should be specified, and the record of effluent quality should be reviewed.
The two should be compared and any discrepancies should be explained. Exist-
ing water rights should be investigated if a change is anticipated in disposal
practice. In the western states, where water rights are generally of greater
concern, it may be helpful to consult with the state agency involved in water
rights.
B. 4. C OMPOSITION O F E FF LUENT
The composition of the effluent to be applied to the land should be evaluated with
respect to the constituents in the following discussion. The constituents of
importance in an individual case will depend upon the effluent limitations,
groundwater protection criteria from the BPT document, and guidelines for
irrigation water quality. The concentrations determined should be related to
existing pre application treatment practices and to additional preapplication
treatment requirements as discussed in Section E. The degree to which the
list is adhered to is dependent upon the type and size of the project, and the
sources of wastewater. Where high constituent concentrations are suspected,
they should be evaluated more thoroughly. Because the acceptability of
wastewater characteristics for land application will depend heavily upon site
characteristics, type and purpose of system, and loading rates, the evaluation
cannot be completed until these interactions are considered.
B.4.a. Total Dissolved Solids
The aggregate of the dissolved compounds is the TDS (total dissolved solids).
The TDS content, which is related to the EC (electrical conductivity), is gen-
erally more important than the concentration of any specific ion. High TDS
(total dissolved solids) wastewater can cause a salinity hazard to crops,
expecially where annual evapotranspiration exceeds annual precipitation.
A general classification as to salinity hazard by TDS content and electrical
conductivity is given in Table 1. It should be noted that these values were
developed primarily for the arid and semiarid parts of the country. The
24
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effects of high TDS on crop yields are discussed in Section E (I-E. 3. a.).
High-TDS wastewater may also create problems if allowed to percolate to
the permanent groundwater.
Table 1. GENERAL GUIDELINES FOR SALINITY IN
IRRIGATION WATERa [110]
Classification^
TDS, mg/1 EC, mmhos/cm
Water for which no detrimental
effects are usually noticed
Water that can have detrimental
effects on sensitive crops
Water that can have adverse
effects on many crops, re-
quiring careful management
practices
Water that can be used for
tolerant plants on permeable
soils with careful management
practices
500
0.75
500-1,000 0.75-1.50
1,000-2,000 1.50-3.00
2,000-5,000 3.00-7.50
a. Normally only of concern in arid and semiarid parts of the country.
b. Crops vary greatly in their tolerance to salinity (TDS or EC). Crop
tolerances are given in Section E.
B.4.b. Suspended Solids
Suspended solids in applied effluents are important because they have a
tendency to clog sprinkler nozzles and soil pores and to coat the land
surface. A large percentage of the suspended solids can be removed easily
by sedimentation. When applied to the land at acceptable loading rates,
almost complete removal can be expected from the percolate.
B. 4. c. Organic Matter
Organic matter, as measured by BOD, COD, and TOG, is present in the
dissolved form as well as in the form of suspended and colloidal solids.
Ordinarily, concentrations are low enough not to cause any short-term effects
on the soil or vegetation. Organic compounds, such as phenols, surfactants,
and pesticides, are usually not a problem but in high concentrations they can
be toxic to microorganisms.
25
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BOD applied is removed from the wastewater very efficiently by each land-
application method. The loading applied, however, will greatly influence the
resting period for soil reaeration and may influence liquid loading rates
(I.E.l.d.).
For groundwater quality protection, the organic forms to be considered include
carbon chloroform extractable and carbon alcohol extractable compounds as
well as pesticides and foaming agents. There are few data on removal of
these compounds by soils from applied municipal effluents.
B. 4. d Nitrogen Forms
Nitrogen contained in wastewater may be present as: ammonium, organic,
nitrate, and nitrite; with ammonium and organic usually being the principal
forms. In a nitrified effluent, however, nitrate nitrogen will be the major
form. Relationships between these forms and renovation mechanisms for land-
application treatment systems are explained in references [125, 130, 1411.
Because nitrogen removal is sensitive to a variety of environmental conditions,
monitoring of nitrogen concentrations is usually required. To avoid confusion,
concentrations of each form should be expressed as nitrogen.
Nitrogen is important because when it is converted to the nitrate form, it is
mobile and can pass through the soil matrix with the percolate. In ground-
water, nitrates are limited to 10 mg/1 by the proposed BPT criteria, while
in surface waters nitrates may also aggravate problems of eutrophication.
Nitrogen loadings and removal mechanisms are discussed in Section E
(I-E.l.b.).
B. 4. e. Phosphorus
Phosphorus contained in wastewater occurs mainly as inorganic compounds,
primarily phosphates, and is normally expressed as total phosphorus. 4 Phos-
phorus removal is accomplished through plant uptake and by fixation in the soil
matrix. The long-term loadings of phosphorus are important because the fixa-
tion capability of some soils may be limited over the normal expected lifespan of
the system (I-E. 1. c.). Phosphorus that reaches surface waters as a result of
surface runoff or interception of groundwater flow may aggravate problems of
eutrophication. Detailed discussions of phosphorus reactions in soil are con-
tained in Bailey [9] and Reed[l30].
B.4.f. Inorganic Ions
Inorganic chemical constituents in wastewater can present problems to land-
application systems, through the effect of specific ions on the soil, plants, and
groundwater. Irrigation requirements for chlorides, sulfates, boron, and car-
bonates are detailed in Water Quality Criteria [110, 176]. Concentrations of
TDS, boron, sodium, chlorides, and carbonates that could cause various dele-
terious effects on plants are listed in Table 2. In most cases, the concentra-
tions present in municipal wastewater are within these limits; however, a
complete mineral analysis of the wastewater should be conducted. Problems
encountered from high boron concentrations and high sodium adsorption ratios
26
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Table 2. WATER-QUALITY GUIDELINES [7]
Problem and related constituent
No problem
Guideline values
Increasing
problems
Severe
Salinity
EC of irrigation water, in millimhos/cm
Permeability
EC of irrigation water, in mmho/cm
SAR (Sodium adsorption ratio)
Specific ion toxicityb
From root absorption
Sodium (evaluate by SAR)
Chloride, me/1
Chloride, mg/1
Boron, mg/1
From foliar absorption (sprinklers)
Sodium, me/1
Sodium, mg/1
Chloride, me/1
Chloride, mg/1
Miscellaneous
NH.-N
NO
^ N-}~
sensitive crops
<0.75
>0.5
<6. 0
<3
<4
<142
<0.5
<3.0
<69
<3.0
<106
<5
0.75-3.0
<0.5
6.0-9.0
3.0-9.0
4.0-10
142-355
0.5-2.0
>3.0
>69
>3.0
>106
5-30
>3.0
<0.2
>9. 0
>9.0
>10
>355
2.0-10.0
>30
HCO , me/1
HCO^, mg/1
pH
["only with overhead"!
[sprinklers J
<1. 5
<90
Normal range =
1.5-8.5
90-520
6.5-8.4
>8.5
>520
a.
b.
d.
Assumes water for crop plus needed water for leaching requirement (LR) will be applied. Crops
vary in tolerance to salinity. Refer to tables for crop tolerance and LR. mmho/cm x 640 =
approximate total dissolved solids (TDS) in mg/1 or ppm; mmho x 1,000 = micromhos.
Most tree crops and woody ornamentals are sensitive to sodium and chloride (use values shown).
Most annual crops are not sensitive (use salinity tolerance tables).
Leaf areas wet by sprinklers (rotating heads) may show a leaf burn due to sodium or chloride
absorption under low-humidity, high-evaporation conditions. (Evaporation increases ion
concentration in water films on leaves between rotations of sprinkler heads.)
Excess N may affect production or quality of certain crops, e.g., sugar beets, citrus, grapes,
avocados, apricots, etc. (1 mg/1 NO3-N = 2. 72 Ib N/acre-ft of applied water.)' ECO^ with
overhead sprinkler irrigation may cause a white carbonate deposit to form on fruit and leaves.
Note: Interpretations are based on possible effects of constituents on crops and/or soils. Guidelines
are flexible and should be modified when warranted by local experience or special conditions of
crop, soil, and method of irrigation.
27
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are perhaps the most common; however, heavy metals and trace elements can
also cause problems. Recommended maximum concentrations for trace ele-
ments in irrigation waters are given in Table 3. For groundwater quality
protection, the constituents included in the BPT criteria are of importance.
B. 4. f. 1. Heavy Metals and Trace Elements - Although some heavy metals
are essential in varying degrees for plant growth, most are toxic, at varying
levels, to both plant life and microorganisms. The major risk to land treat-
ment systems from heavy metals is in the long-term accumulation in the soil,
because they are retained in the soil matrix by adsorption, chemical precipita-
tion, and ion exchange. Retention capabilities are generally good for most
metals in most soils especially for pH values above 1, Page [113], Chapman
[27], and Mortvedt [107] have reviewed and discussed the fate and effects of
heavy metals in soils.
Generally, zinc, copper, and nickel make the largest contributions to the total
heavy metal content. Zinc is used as a standard for plant toxicity, with copper
being twice as toxic and nickel being eight times as toxic [63]. A "zinc equiva-
lent" can thus be determined for these two metals. Research is continuing in
an attempt to determine the relative phytotoxicities of other metals. For
infiltration-percolation systems the effects of heavy metals reaching the ground-
water must be considered (see I-C. 2. e.).
B. 4. f. 2. Exchangeable Cations - The effect of concentrations of sodium,
calcium, and magnesium ions deserves special consideration. They are
related by the sodium adsorption ratio (SAR), defined as [37]:
SAR = Na (1)
Ca + Mg
2
where Na, Ca, and Mg are the concentrations of the respective ions in milli-
equivalents per liter of water. High SAR (greater than 9) values may adversely
affect the permeability of soils [7]. Other exchangeable cations, such as
ammonium and potassium, may also react with soils. High sodium concentra-
tions in soils can also be toxic to plants, although the effects on permeability
will generally occur first [110].
B.40f. 3. Boron Boron is an essential plant micronutrient but is toxic to
many plants at 1 to 2 mg/1 [96]. In addition to the limited plant uptake, boron
can be removed from solution by adsorption and fixation in the soil in the
presence of iron and aluminum oxides [20], but only to a limited extent [130],
Relative tolerances of various plants to boron are presented in references [27,
37, 1761.
28
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Table 3. RECOMMENDED MAXIMUM CONCENTRATIONS OF
TRACE ELEMENTS IN IRRIGATION WATERS [llO]a
For use up to 20 years
For waters used continuously on fine-textured soils
on all soil, of pH 6. 0 to 8. 5,
Element mg/1 mg/1
Aluminum 5.0 20.0
Arsenic 0. 10 2.0
Beryllium 0.10 0.50
Boron 0.75 2.0-10.0
Cadmium 0.010 0.050
Chromium 0. 10 1.0
Cobalt 0.050 5.0
Copper 0.20 5.0
Fluoride 1.0 15.0
Iron 5.0 20.0
Lead 5.0 10.0
Lithium 2.5b 2.5b
Manganese 0.20 10.0
Molybdenum 0.010 0.050C
Nickel 0.20 2.0
Selenium 0.020 0.020
Zinc 2.0 10.0
a. These levels will normally not adversely affect plants or soils. No data are available for
mercury, silver, tin, titanium, tungsten.
b. Recommended maximum concentration for irrigating citrus is 0.075 mg/1.
c. For only acid fine-textured soils or acid soils with relatively high iron oxide contents.
29
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B. 4. g. Bacteriological Quality
Microorganisms, primarily bacteria, are normally present in large quantities
in wastewater. The bulk of these microorganisms can be removed by conven-
tional treatment, and the soil mantle is quite efficient in the removal of bacteria
and probably viruses through the processes of filtration and adsorption [40, 43,
44, 77, 78, 143]. Problems may arise, however, in the actual application pro-
cess, especially in spraying, where aerosols could present a health hazard
(I-F. 2. d.). High degrees of preapplication treatment, including disinfection,
may be necessary, particularly in cases in which public access to the applica-
tion area is allowed.
B.4.h. Projected Changes
The possibility of changes in wastewater characteristics should be investigated,
both from the standpoint of projected future permanent changes and seasonal
variations. Changes in characteristics may reflect those in water supply and
local industries. Seasonal variations may be the result of variations in water-
supply characteristics, domestic use, industrial use, and population fluctuations.
Adverse changes in wastewater mineral quality may require selection of alter-
nate crops or changes in loading rates.
B.4.L Industrial Components
Industrial components often present in municipal wastewater normally require
special consideration because of the occurrence of abnormal concentrations of
certain constituents and their influence on the overall wastewater characteris-
tics. Industries that discharge wastewater into municipal systems should be
studied on the basis of: existing concentrations, seasonal variations, and ex-
pected changes in the plant process which might affect wastewater characteris-
tics. Industrial wastewater ordinances, generally designed to prevent discharge
to sewers of elements and compounds in concentrations toxic to microorganisms,
should be analyzed with regard to limiting the discharge of materials such as
sodium or boron which may be toxic to plants. Reference should be made to the
Pretreatment Standards (40 CFR 128).
B. 4. j. B PT C onstituents
The proposed BPT document [3] presents information and criteria on waste
management alternatives for achieving best practicable treatment including
land application, treatment and discharge, and reuse systems. Where land
application systems discharge to surface waters, the discharge quality criteria
are the same as for the conventional methods. Where land-application effluents
result in permanent groundwater, the BPT document sets forth guidelines for
protection of the groundwater quality which include chemical, pesticide, and
bacteriological constituents. These guidelines should be consulted for limitations
on any constituents not discussed previously in this section.
30
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Section C
EVALUATION OF POTENTIAL SITES
The process of site selection for land-application systems should include an
initial evaluation on the basis of criteria presented in this section. The environ-
mental setting should be described and the individual site characteristics should
be analyzed. Each site should then be reevaluated in light of considerations of
treatment methods, design, and expected impacts.
C.I. GENERAL DESCRIPTION
A preliminary step in site evaluation should be a general description of the land
involved. The environmental setting should be described witn emphasis on:
The location of the site
The relationship to the overall land-use plan
The proximity to surface water
The number and size of available land parcels
Location and use of any existing potable wells (I-C. 2. e. 6).
C.I, a. Location
The descriptio i of site location should include both the distance and elevation
difference from the treatment plant or wastewater collection area. Both will
affect the feasibility and economics of the transmission of the wastewater to the
site. Any significant obstructions to transmission, such as rivers, freeways,
or developed residential areas, should be noted.
C. l.b. Compatibility with Overall Land-Use Plan
Of significant importance in site selection is the compatibility of the intended
use with regional land-use plans. The regional planners or the planning com-
mission should be consulted as to the future use of potential sites.
During a visit to the site, the current use, adjacent land use, and proximity to
areas developed for residential, commercial, or recreational activities can be
ascertained. On the basis of a review of master plans or discussions with local
planners, the oroposed future use, zoning, and proposed development of the ad-
jacent area cau be determined.
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C. 1. c. Proximity to Surfac e Water
In many cases, the proximity of the potential site to a surface-water body may
be of significance. For overland flow systems, and systems with underdrains
or pumped withdrawal, discharge of renovated water to a surface-water body
may be necessary. In such a case, the feasibility and cost of transmission may
become important considerations. The relationship of surface water to the
overall hydrology of the area, and particularly to the groundwater, should be
evaluated. Water-quality aspects and site drainage are considered later in this
section.
C. l.d. Number and Size of Available Land Parcels
The relative availability of land at potential sites, together with the probable
price per acre, must be defined early in the evaluation. The number and size
of available parcels will be of significance, especially in relation to the com-
plexity of land acquisition and control a subject that is discussed at the end of
this section.
C.2. DESCRIPTION OF ENVIRONMENTAL CHARACTERISTICS
The environmental characteristics of a potential site that may affect the future
selection of a land-application method and the subsequent design of the treat-
ment system include: climate, topography, soil characteristics, geologic for-
mations, groundwater, and receiving water. The degree of detail required for
the evaluation of any one particular characteristic is highly variable and depend-
ent upon the size of the project and the severity of local conditions. This dis-
cussion cannot cover all conceivable aspects, but the major environmental
factors will be discussed.
C.2.a. Climate
Local climatic conditions will affect a large number of design decisions including:
the method of land application, storage requirements, total land requirements,
and loading rates. The National Weather Service, local airports, and univer-
sities are potential sources of climatological data. The data base should en-
compass a long enough period of time so that long-term averages and frequencies
of extreme conditions can be established. Each of the climatic factors is dis-
cussed in the following paragraphs.
C. 2. a. 1. Precipitation Analysis of rainfall data should be conducted with
respect to both quantities and seasonal distribution. Quantities should be ex-
pressed in terms of averages, maximums, and minimums for the period of
record. A frequency analysis should be made to determine the design annual
precipitation, which will normally be the maximum precipitation values having
a return period of a given number of years (the wettest year in a given number
32
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of years). The plot of precipitation against return period on probability paper,
a method commonly used to display the results of the frequency analysis, is
illustrated in Figure 2. Different return periods may often be used for the
determination of liquid loading rates (I-E. 1. a) and the determination of storage
capacity (I-E. 4.).
In cold regions, an analysis of the snow conditions with respect to depth and
period of snow cover may also be required. In most cases, except for some
infiltration-percolation systems, periods of snow cover will necessitate storage
of the effluent for later application.
C.2.a.2. Storm Intensities An investigation of storm data for the period of
record should be included in the precipitation study, A frequency analysis
25
20
10
1.10 2.0 10 50 100
RETURN PERIOD IN YEARS
500
Figure 2. Typical frequency analysis for total annual precipitation
33
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should be performed to determine the relationship between storm intensity,
duration, and frequencies or return periods. The design storm event can then
be analyzed for the amount of runoff it would produce and the need for any
runoff control features can be determined.
C.2.a.3. Temperature - Temperature analysis should include the range of
temperatures during the various seasons. Maximum periods, of freezing con-
ditions, particularly periods in which the ground is frozen, are of special interest
in determining periods of inoperation. The effects of temperature are of impor-
tance in the selection of a land-application method, the design of the loading
schedule, and in the determination of storage requirements. For irrigation of
annual crops, the probable early and late season frost dates need to be
determined.
C.2.a.4. Evapotranspiration - Evapotranspiration is the evaporation of water
from the soil surface and vegetation plus the transpiration of water by plants.
Evapotranspiration rates are dependent upon a number of factors, including
humidity, temperature, and wind, and will significantly affect the water balance
in almost all cases. Typical monthly totals are available in most areas from
the National Weather Service, nearby reservoirs, the Agricultural Extension
Service, or Agricultural Experiment Stations.
C. 2. a. 5o Wind Analysis of wind velocity and direction may be required, and
should contain seasonal variations and frequency of windy conditions. Wind
analysis is of importance primarily for spray application systems, where windy
conditions may require large buffer zones or temporary cessation of application.
C.2.b. Topography
The topography of the site and adjacent land is critical to the design of land-
application systems. Normally, a detailed topographic map of the area will be
necessary for site selection and the subsequent system design. Topographic
maps are available from the U.S. Geological Survey. Information to be gained
from an analysis of the topography is listed in the following discussion.
C. 2.b. 1. Ground Slope - Ground slope, usually expressed as a percentage, is
an important site characteristic for the determination of the land treatment
method and application technique. For example, the success of an overland
flow system is highly dependent upon ground slope, and irrigation by flooding
normally requires slopes of less than 1 percent. Foliated hillsides with slopes
of up to 40 percent have been sprayed successfully with effluent [140, 142].
Ranges of values for successful operation are given in Section D.
C. 2.b. 2. Description of Adjacent Land The topography of land adjacent to the
potential site should be included in the topographic evaluation. Of primary con-
cern are the effects of storm runoff, both from adjacent land onto the site and
34
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from the site onto adjacent lands and surface water bodies. Also of concern will
be areas downslope from the site where seeps may occur as a result of increased
groundwater levels.
Co 2.b. 3. Erosion Potential The erosion potential of the site and adjacent land
should be predicted, and any required corrective action outlined. Both waste-
water application rates and storm runoff should be considered. The typical Soil
Conservation Service (SCS) evaluation of soils includes an analysis of erosion
potential, which is valuable in determing the possible extent of the problem.
C. 2.b. 4, Flood Potential The site topography should be evaluated and histori-
cal data reviewed to determine the possibility of flooding on the site or adjacent
areas. Sites prone to flooding, such as flood plains, may still be suitable for
land application but normally only if the physical equipment is protected and off-
site storage is provided.
C. 2.b. 5. Extent of Clearing and Field Preparation Necessary The extent of
clearing and field preparation is largely dependent upon the selection of land-
application method, the application technique, and the existing vegetation. In-
cluded in the evaluation should be:
The extent of clearing of existing vegetation (if necessary)
Disposition of cleared material
Necessary replanting
Earthwork required
Some of this information would be developed in detail in the environmental
assessment.
C.2.C. Soil Char act eristic s
Soil characteristics are often the most important factors in selection of both the
site and the land-application method. Definite requirements for soil character-
istics exist for each of the method alternatives, with overland flow and
infiltration-percolation having the strictest requirements. Information on soil
characteristics can be obtained from the Soil Conservation Service, many uni-
versities, and the Agricultural Extension Service.
C. 2. c. 1. Type and Description The soil at the potential site should be de-
scribed in terms of its physical and chemical characteristics. Important physi-
cal characteristics include texture and structure, which are largely influenced
by the relative percentages of the mechanical, or particle-size, classes (gravel,
sand, silt, and clay). Chemical characteristics which may be of importance
are: pH, salinity, nutrient levels, and adsorption and fixation capabilities for
various inorganic ions. The following series of tests is suggested:
35
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pH
Salinity or electrical conductivity
Organic matter
Total exchangeable cations
Levels of nitrogen, phosphorus, potassium, magnesium, calcium,
and sodium
Percent of the base exchange capacity occupied by sodium, potassium,
magnesium, calcium, and hydrogen
Reference is suggested to the University of California manual for analysis of
soils, plants, and waters [26].
C. 2. c. 2. Infiltration and Percolation Potential - The potential of the soil for
both infiltration and percolation is of great importance in the site selection and
selection of application method. Infiltration, the entry of water into the soil,
is normally expressed as a rate in inches per hour. The rate generally de-
creases with wetting time and previous moisture content of the soil; conse-
quently, it should be determined under conditions similar to those expected
during operation. Percolation is the movement of water beneath the ground
surface both vertically and horizontally, but above the water table. It is normally,
dependent upon several factors, including soil type; constraints to movement,
such as lenses of clay, hardpan, or rock; and degree of soil saturation. The
limiting rate (either infiltration or percolation) must be determined and reported
in inch/day (cm/day) or inch/week (cm/week).
The standard percolation test is not recommended for determination of infil-
tration or percolation rates. The test results are not reproducible by different
fieldmen [182] and are affected by hole width, gravel packing of holes, depth of
water in holes, and the method of digging the holes. More importantly, if sub-
surface lenses exist, the water in the test hole will move laterally, with the
result being a fairly high percolation rate. Designing a liquid loading rate on
that basis would be disasterous because, when the entire field is loaded, the
only area for flow is the few feet of depth to the lens times the field perimeter.
Instead of using the percolation test, it is suggested that several or more of the
following approaches be used as a basis of determining infiltration and perco-
lation rates: (1) consultation with Agriculture Extension Service agents, state
or local government soil scientists, or independent soil specialists; (2) engineer-
ing analysis of several soil borings and soil classifications; (3) engineering
analysis of soil profiles supplied by the Soil Conservation Service (SCS); (4) con-
sultation with county agents, agronomists, or persons having farming experience
with the same, similar, or nearby soils; and (5) experience from pilot studies
on parts of the field to be used.
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C.2.C.3. Soil Profile The soil profile, or relation of soil characteristics to
depth, will normally be required for all site evaluations. Generally, the pro-
file should be determined to depths of 2 to 5 feet (0. 61 to 1. 52 m) for overland
flow, at least 5 feet (1. 52 m) for irrigation, and at least 10 feet (3. 05 m) for
infiltration-percolation. The underlying soil layers should be evaluated princi-
pally for their renovation and percolation potentials. Lenses or constraints to
flow below these levels should be located.
C. 2. c 4. Evaluation by Soil Specialists In most cases, an evaluation by soil
specialists will be necessary to determine the overall suitability of the soil
characteristics for the intended use. SCS representatives, soil scientists,
agronomists, and Agricultural Extension Service representatives are possible
sources to be consulted.
C.2.d. Geologic Formations
A basic description of the geologic conditions present and their effects should be
required for all site evaluations. Infiltration-percolation sites and sites with
suspected adverse geological conditions will require a relatively detailed analy-
sis, while considerably less is required for most overland flow sites and many
irrigation systems. Data on geological formations are available from the U.S.
Geological Survey, state geology agencies, and occasionally from SCS or U.S.
Bureau of Reclamation publications.
C.2.d. 1. Type and Description The geologic formations should be considered
in terms of: the structure of the bedrock, the depth to bedrock, the lithology,
degree of weathering, and the presence of any special conditions, such as glacial
deposits. The presence of any discontinuities, such as sink holes, fractures or
faults, which may provide short circuits to the groundwater, should be noted and
thoroughly investigated. In addition, an evaluation of the potential of the area
for earthquakes and their probable severity will often be of importance to the
future design of the system.
C. 2.d. 2. Evaluation by Geologists -In many situations, an evaluation by a
geologist or geohydrologist will be necessary. The geologist will be of value
both in the investigation of the geologic conditions and in the evaluation of their
effects. Of primary importance in the evaluation are the effects of the geology
on the percolation of applied wastewater and the movement of groundwater.
C. 2 o e. Gr oundw at er
An investigation of groundwater must be conducted for each site, with particular
detail for potential infiltration-percolation and irrigation sites. Evaluations
should be made by the engineer to determine both the effect of groundwater levels
on renovation ca abilities and the effects of the applied wastewater on ground-
water movement and quality with respect to the BPT requirements.
37
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C. 2. e. 1. Depth to Groundwater - The depth to groundwater should be determined
at each site, along with variations throughout the site, and seasonal variations.
Depth to groundwater is important because it is a measure of the aeration zone
in which renovation of applied wastewater takes place. Generally, the ground-
water depth requirements are:
0 Overland flow - sufficient depth not to interfere with plant growth
Irrigation at least 5 feet (1.52 m)
Infiltration-percolation - preferably 15 feet (4.57 m) or more
Lesser depths may be acceptable where underdrains or pumped withdrawal
systems are utilized.
When several layers of groundwater underlie a particular site, depths should be
determined to each, unless they are separated by a continuous impervious
stratum. The quality and current and planned use of each layer should also
be determined.
C. 2.e.2. Groundwater Flow In most cases, the groundwater should be evalu-
ated for direction and rate of flow and for the permeability of the aquifer. This
evaluation may be unnecessary when percolation is minimal, as with an over-
land flow and some irrigation systems. For systems designed for high perco-
lation rates, effects on the groundwater flow must be predicted.
Additionally, data on aquifer permeability may be evaluated, together with
groundwater depth data, to predict the extent of the recharge mound. The di-
rection of flow is important to the design of the monitoring system and should be
traced to determine whether the groundwater will come to the surface, be inter-
cepted by a surface water, or join another aquifer.
C. 2. e. 3. Perched Water Perched water tables are the result of impermeable
or semipermeable layers of rock, clay, or hardpan above the normal water table
and may be seasonal or permanent. Perched water can cause problems for land-
application systems by reducing the effective renovative depth. Sites should be
investigated both for existing perched water tables and for the potential for de-
velopment of new ones resulting from percolating wastewater. The effect of
perched water tables should be evaluated, and the possibility of using under-
drains investigated. A distinction should be made between permanent ground-
water protected by impermeable strata and perched groundwater above such
strata.
C. 2. e. 4. Quality Compared to Requirements The quality of the groundwater
is of great interest, especially in cases in which it is used for beneficial purposes
or differs substantially from the expected quality of the renovated wastewater.
The existing quality should be determined and compared to quality requirements
for its current or intended use. The proposed requirements for BPT[3J include
limitations for chemical constituents, pesticide levels, and bacteriological
quality as discussed in I-B.4.
38
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C. 2. e. 5. Current and Planned Use Both current and planned use of the ground-
water should be determined, and the quality requirements for the various uses
detailed. The distance from the site to the use areas may also be of importance,
because further renovation may occur during lateral movement.
C. 2. e. 6. Location of Existing Wells Much of the data required for ground-
water evaluation may be determined through use of existing wells. Wells that
could be used for monitoring should be listed and their relative location described.
Historical data on quality, water levels, and quantities pumped that may be
available from the operation of existing wells may be of value. Such data might
include seasonal groundwater-level variations, as well as variations over a
period of years. Logs containing soil data may be available from the drillers
of these wells, and this information could augment data from soil borings or
geological maps. It should be noted that much information on private wells can
be obtained only with the owner's consent. Determining ownership and locating
owners can be difficult and time-consuming.
C.2.f. Receiving Water (Other than Groundwater)
Land-application systems in which renovated water is recovered, particularly
overland flow systems, may require discharge into a receiving surface water
body. Such a discharge would require a permit under the National Pollution
Discharge Elimination System (NPDES). If the receiving water is designated
as effluent limited, the requirements for secondary treatment apply. If the
receiving water is designated as water-quality limited, pursuant to Section 303
of P.L. 92-500, treatment must be provided consistent with the established
water-quality standards. Included in the evaluation should be descriptions of:
the type of body (lake, stream, etc.), its current use and water qualitys pre-
scribed water-quality standards and effluent limitations, and water-rights
considerations. Special water-quality requirements and other considerations
may exist when the potential receiving water is an intermittent stream. The
current use of the water, together with its prescribed water-quality standards,
will determine the degree of treatment necessary by the land-application system.
Water-rights considerations may require that certain quantities of renovated
water be returned to a particular water body, particularly in the western states.
In cases in which a change in method of disposal or point of discharge is contem-
plated, the state agency of other cognizant authority should be contacted, and
the status of all existing water rights thoroughly investigated.
C. 3. METHODS OF LAND ACQUISITION OR CONTROL
After potential sites have been selected, alternative methods of land acquisition
or control should be assessed. Alternative methods include: (1) outright pur-
chase of land with direct control, (2) appropriate lease of land with direct control,
(3) purchase of land with lease back to farmer for the purpose of land application,
and (4) contract with user of wastewater. An appropriate lease would be one in
which the investment of funds for construction of the land-application system
would be protected and direct control of the effluent application would be retained
by the municipality or district.
39
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The selection of an acquisition and control method is highly dependent on the
selected method of application. Infiltration-percolation and overland flow sys-
tems normally require a high degree of control and may often be suitable only
if outright purchase of the land is possible. Because land control requirements
are more flexible for irrigation systems, the leasing of land to agricultural
users may be possible. Leasing of required land is often best suited to pilot
studies and temporary systems.
Grant eligibility has not been considered in the discussion of these methods.
For land acquisition to be eligible for a construction grant, under P. L. 92-500,
the land must be an integral part of the treatment process or is to be used
for ultimate disposal of residues resulting from such treatment.
40
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Section D
CONSIDERATION OF LAND-APPLICATION ALTERNATIVES
On the basis of the project objectives and the characteristics of the selected
potential sites, various methods of land application should be considered.
Alternatives can be classified into three main groups: irrigation, infiltration-
percolation, and overland flow or spray-runoff. These alternatives differ
considerably, with respect to both use for different objectives and require-
ments for site characteristics. Each method is shown schematically in Figure
3. The various possible uses for land-application approaches following some
initial treatment are compared in Table 4. These objectives should then be
related to the project objectives (I-A). Site characteristics discussed in the
previous section that affect alternative selection will be briefly related to
each of the three alternatives in the following presentation.
Table 4. COMPARISON OF IRRIGATION, OVERLAND FLOW,
AND INFILTRATION-PERCOLATION OF MUNICIPAL WASTEWATER
Objective
Use as a treatment process with
a recovery of renovated watera
Irrigation
0-70%
recovery
Type of approach
Overland flow
50 to 80%
recovery
Infiltration-
percolation
Up to 97%
recovery
Use for treatment beyond
secondary:
1. For BODg and suspended
solids removal
85-99%
2. For nitrogen removal
3. For phosphorus removal
Use to grow crops for sale
Use as direct recycle to the
land
Use to recharge groundwater
Use in cold climates
85+%
80-99%
Excellent
Complete
0-70%
Fair0
70-90%
40-80%
Fair
Partial
0-10%
_d
0-50%
60-95%
Poor
Complete
Up to 97%
Excellent
a. Percentage of applied water recovered depends upon recovery technique and the
climate.
b. Dependent upon crop uptake.
c. Conflicting datawoods irrigation acceptable, cropland irrigation marginal.
d. Insufficient data.
41
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SPRAY OR-
SURFACE
APPLICATION-
ROOT ZONE
SUBSOIL
EVAPORATION
'N
/ V
\fi
-CROP
V.V,^
v<
A
J V
/v
f- \
(a) IRRIGATION
SLOPE
VARIABLE
-DEEP
PERCOLATION
EVAPORATION
SPRAY APPLICATION
SLOPE 2-4%
GRASS AND VEGETATIVE LITTER
RUNOFF
COLLECTION
(b) OVERLAND FLOW
EVAPORATION
INFILTRATION
ZONE OF AERATION
AND TREATMENT
SPRAY OR
SURFACE APPLICATION
PERCOLATION THR0USH
UNSATUBATfcB ZONE
RECHARGE MOUND ^-^ ^
___ «^.-"T^-T^!>^'1^v'!>^<;/;vvvv'!'!';A'X'>!vT^t;^v-!v-^.>?1?^ »-^ »4«
YMiMiM'IvC'iisiI'M'M'M'M'I'
. ^. . . . .... ..T^^T.". .'.....
\>>*B«*****« I »«v^»
*.'\»'''''.'.'.''''''' «"T*7*
(c) INFILTRATION-PERCOLATION
/
Figure 3. Methods of land application
OLD WATER TABLE-
42
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D. 1. IRRIGATION
The most common method of treatment by land application is irrigation. It is
the controlled discharge of effluent, by spraying or surface spreading, onto
land to support plant growth. The wastewater is "lost" to plant uptake, to
air by evapotranspiration, and to groundwater by percolation. Liquid loading
rates up to 4 inches (10. 2 cm) per week on a seasonal basis and 8 feet (2.44 m)
per year on an annual basis are in this category. Systems with liquid loading
rates exceeding these (other than overland flow) are normally considered to be
of the infiltration-percolation type.
The range of suitable site characteristics for irrigation systems is wide. The
major criteria generally considered preferable are as follows:
Climate warm-to-arid climates are preferable, but more severe
climates are acceptable if adequate storage is provided for wet or
freezing conditions.
Topography slopes up to 15 percent for crop irrigation are accept-
able provided runoff or erosion is controlled.
« Soil type loamy soils are preferable, but most soils from sandy
loams to clay loams are suitable.
Soil drainage well-drained soil is preferable, however, more
poorly drained soils may be suitable if drainage features are included
in the design.
Soil depth uniformly 5 to 6 feet (1. 52 to 1. 83 m) or more through-
out sites is preferred for root development and wastewater renovation.
Geologic formations lack of major discontinuities that provide short
circuits to the groundwater is necessary.
Groundwater minimum depth of 5 feet (1. 52 m) to groundwater is
normally necessary to maintain aerobic conditions, provide necessary
renovation, and prevent surface waterlogging. May be obtained by under-
drains or groundwater pumping.
D. 1. a. Purpose of Irrigation
The suitability of a particular site, a particular effluent, and the future design
of the system will depend, to a large degree, on the intended purpose of irriga-
tion. Three distinct purposes have been identified.
43
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Optimization of crop yields
Maximization of effluent application
Landscape irrigation
Each purpose is defined and major design considerations are introduced in the
material that follows:
D. 1. a. 1. Optimization of Crop Yields - Irrigation systems designed for this
purpose are often used in situations in which effluent is offered to farmers for
their own use. The application rate for the effluent is based only on the needs
of the crop; normally, no more effluent is applied than is necessary for opti-
mum crop yield. Relatively wide variations in application rates usually occur
as a result of seasonal variations in crop moisture demand and seasonal
precipitation. Consequently, total land and storage requirements may be
relatively high. Operation without purchase of land for irrigation may be
possible through contracts with users of the wastewater.
D. 1. a. 2. Maximization of Effluent Application - In irrigation systems designed
for maximum effluent application, considerably higher loading rates may be
used than are required for crop growth. Crops of lesser economic value may
be chosen on the basis of their water tolerance, nutrient uptake, or tolerance
to certain wastewater constituents. Greater amounts of percolation may also
be planned for, as design liquid loading rates will exceed the plant
requirements.
Forestland irrigation systems can also be designed for maximum effluent
application. The greater suitability of forestland to cold-weather operation
may result in a more evenly distributed loading schedule and can reduce
storage requirements. However, the long-range nutrient removal capabilities
of forest systems are generally less than for most field crops.
Forestland irrigation can result in the succession of water-tolerance species in
place of naturally occurring vegetation. This occurrence should be considered
in the environmental assessment.
D. 1. a. 3. Landscape Irrigation - Irrigation of turf, especially in recreational
areas, such as parks and golf courses, requires special consideration. The
condition of the turf is normally of primary importance, and application rates
must be adjusted for this purpose. Public health considerations are also of
great importance, with high degrees of treatment prior to application, includ-
ing disinfection, normally being required. Additional measures, such as
irrigation during off-hours, are often necessary.
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D. l.b. Application Techniques
Three application techniques are employed in irrigation systems (Figure 4):
Spraying
Ridge and furrow
Flooding
Topography, soil conditions, weather conditions, agricultural practice, and
economics are factors to be considered in technique selection. General
design features for each technique are described in reference [125, 184].
D. 1. b. 1. Spraying Spraying involves the application of effluent above the
ground either through nozzles or sprinkler heads. Other elements of the
system include: pumps or a source of pressure, supply mains, laterals, and
risers. Design of a system can be quite variable; it can be portable or per-
manent, moving or stationary. Spray systems are the most efficient for
uniform flow distribution, but such systems are also generally the most expen-
sive. High wind, a problem common to spray irrigation systems, adversely
affects efficiency of distribution and can also spread aerosol mists. Hydraulic
design factors for spraying systems are included in references [114, 115, 155].
D. l.b. 2 Ridge and Furrow Ridge and furrow irrigation is accomplished by
gravity flow of effluent through furrows, from which it seeps into the ground.
Utilization of this technique is generally restricted to relatively flat land, and
extensive preparation of the ground is required. The operating cost is rela-
tively low, and the technique is well suited to certain row crops. Uniformity
of distribution, however, is fairly difficult to maintain unless the grading of
the land is nearly perfect [184].
D. 1. b. 3. Flooding - Irrigation by flooding is accomplished by inundation of the
land with several inches of effluent. Descriptions of the various flooding
techniques are contained in Wastewater Treatment and Reuse by Land Applica-
tion [125]. The choice of crop is critical because it must be able to withstand
periods of inundation with the technique. The depth of applied effluent and
period of flooding are dependent upon the characteristics of the soil and the
crop grown.
D. 2. INFILTRATION-PERCOLATION
In this form of treatment, wastewater may be applied to the soil by spreading
or spraying. Renovation is achieved as the effluent travels through the soil
matrix by natural physical, chemical, and biological processes. Effluent is
allowed to infiltrate at a relatively high rate, and consequently less land is
required for the same volume than for the two other alternatives. The major
45
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RAIN DROP ACTION-
Ji J I J I ! I II I I'l 1 JF
(a) SPRINKLER
COMPLETELY FLOODED-
TT
(h) FLOODING
(c) RIDGE AND FURROW
Figure 4. Irrigation techniques
46
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portion of the wastewater percolates to the groundwater, while most of the
remainder is lost through evaporation.
Important criteria for site selection include: geologic conditions, soil con-
ditions, and groundwater depth and movement. Because of the high rates of
loading, the geologic conditions and status of the groundwater are relatively
more important than in irrigation or overland flow systems.
Thomas recommends that a depth of 15 feet (4. 55 m) from the surface to the
natural groundwater be considered a minimum [l66J , and Bouwer recommends
that the groundwater recharge mound should not be allowed to rise closer to
the soil surface than a distance of about 4 feet (1.22 m) [l9]. Lesser depths
may be suitable under special conditions; however, a lesser degree of reno-
vation becomes much more probable. The use of an artificial drainage system,
such as pumped withdrawal, should be considered as a means for increasing
groundwater depths.
Well-drained soil is critical to the success of an infiltration-percolation sys-
tem. Acceptable soils include sand, sandy loams, loamy sands, and gravels.
Very coarse sand and gravel are not ideal because they allow wastewater to
pass too rapidly through the first few feet where the major biological and
chemical action takes place [125], Consideration should be given to the infil-
tration surface, which may be planted, overlain with graded sand or gravel, or
left plain. Seasonal variations in temperature and precipitation should also be
considered in determining application rates.
D. 2. a. Purpose of Infiltration-Percolation
Wastewater treatment systems employing infiltration-percolation may be de-
signed for three purposes: groundwater recharge; recovery of renovated water,
using wells or underdrains; and interception of renovated water by a surface
water body.
D.2.a. 1. Groundwater Recharge In systems designed for this purpose, all of
the infiltrated wastewater is allowed to percolate directly to the groundwater.
A mound in the water table will be created under the infiltration area, conse-
quently reducing the renovative distance. Groundwater recharge may be used
for improving poor groundwater quality, for limiting salt-water intrusion, or
merely as an efficient method for treatment and disposal of wastewater.
For the renovated water, the quality requirements for groundwater are given
in the BPT document [3]. The potential for meeting these guidelines depends
upon the soil characteristics, loading rates and cycles, management techniques,
and wastewater characteristics (I-B.4).
D. 2. a. 2. Pumped Withdrawal In cases in which the BPT requirements
cannot be met or the groundwater is of poor quality, renovated water may be
directly withdrawn from the zone of saturation for reuse. Additionally,
pumping from wells, or a system of underdrains, can be used to reduce the
extent of the recharge mound in the water table, thereby increasing renovation
distance.
47
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P. 2. a. 3. Interception by Surface Water - Infiltration-percolation systems may
be designed for situations in which the renovated water moves vertically and
laterally and is subsequently intercepted by a surface water body. This consti-
tutes an indirect discharge to the surface water body.
D. 2. b. Application Techniques
Spreading and spraying are two application techniques that are suitable for
infiltration-percolation. Factors which should be considered in the selection of
the application technique include: soil conditions, topography, climate, and
economics.
D. 2.b. 1. Spreading - Infiltration-percolation by means of spreading is perhaps
the simplest of the land-application techniques. It is also the technique least
affected by cold or wet weather. Several basins are normally used and periods
of flooding are alternated with periods of drying. Application using the ridge
and furrow technique has also been accomplished [125].
D. 2.b. 2. Spraying - Application of effluent at high rates employing spraying
has been accomplished. High-rate spray irrigation systems, where the loading
rate exceeds 4 inches (10. 2 cm) per week, are included in this category. Nor-
mally, vegetation is necessary to protect the surface of the soil and to preclude
runoff. Hydrophytic or water-tolerant grasses are usually chosen. Spraying
of forestland may also be considered for infiltration-percolation.
D. 3. OVERLAND FLOW
Wastewater treatment by this method has been practiced primarily by food-
processing industries, but it appears quite suitable, under certain conditions,
for municipal wastewater. It is nevertheless still in the experimental stage
with regard to municipal systems in this country at this time.
Renovation is accomplished by physical, chemical, and biological means as
wastewater flows through vegetation on a sloped surface. Wastewater is
sprayed over the upper reaches of the slopes and a high percentage of the
treated water is collected as runoff at the bottom of the slope, with the remain-
der being lost to evapotranspiration and percolation. Important criteria for site
selection include: soil conditions, topography, and climate; with the most im-
portant being soil conditions. Soils with minimal infiltration capacity, such as
heavy clays, clay loams, or soils underlain by impermeable lenses, are re-
quired for this method to be effective. Soils with good drainage characteristics
are best suited for other land-application methods [125].
A mantle of 6 to 8 inches (15. 2 to 20. 3 cm) of good topsoil is recommended
[130]. A sloping terrain is necessary to allow the applied wastewater to flow
slowly over the soil surface to the runoff collection system. Slope distance is
a function of the spray diameter, loading rate, and degree of renovation
48
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required. The degree of slope depends on the existing topography and the eco-
nomics of earthwork; however, slopes of 2 to 4 percent are preferred.
D. 3. a. Purpose of Overland Flow
The purpose of the overland flow system, and the intended disposition of its
renovated water, will affect both the site selection and the design of the system.
D. 3. a. 1. Discharge to Surface Waters Collected runoff from most overland
flow systems is discharged to surface waters. Renovated water is collected at
the toe of the slope in cutoff ditches or by similar means and channeled to a
monitoring point before being discharged. The proximity of the site to a re-
ceiving water body and the method of transmission of renovated water to the
discharge point should be considered in the design of such a system.
For a surface water discharge the renovated water must meet the minimum of
secondary treatment requirements or effluent limitations based on water-quality
standards. As shown in Tables 4 and 12 (II-D), the system is capable of a high
degree of treatment. To meet the fecal coliform standards, however, disinfec-
tion of the collected water may be necessary.
D. 3. a. 2. Reuse of Collected Runoff Although largely untried, treated water
from overland flow may be utilized by industry for irrigation or in recreational
impoundments. Storage may be necessary if continuous use is not possible.
Overland flow systems designed for this purpose may be desirable in certain
water-short areas and at sites where transmission of runoff to a receiving
surface water body is impractical or uneconomical.
D. 3. b. Application Techniques
Spraying is the application technique used most commonly for overland flow
systems. Flooding between borders has been used in Melbourne, Australia [76]
but only for 6 months of the year. Factors that should be considered in the
selection of the application technique include: topography, suspended solids
in the wastewater, agricultural practices, and economics.
D. 3.b. 1. Spraying Spraying is the only application technique presently prac-
ticed in this country. Wastewater is applied on the upper reaches of the slope
and is allowed to flow downhill. Spraying may be accomplished by means of
fixed sprinklers or rotating boom-type sprays.
D.3.b.2. Flooding Application by flooding or other surface techniques in
overland flow systems has not been demonstrated in this country, but it has
been practiced successfully in Melbourne, Australia. If high concentrations of
suspended solids are present, settling in the upper reaches may cause an odor
problem. Because uniform distribution is critical, flooding may not be suc-
cessful unless care is taken to produce an extremely smooth terrace with no
cross slope.
49
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D.4. COMBINATIONS OF TREATMENT TECHNIQUES
Wastewater treatment systems must often be designed to meet a wide variety
of demands under an equally wide variety of conditions. Land application
offers possibilities of various combinations of techniques that may be useful in
the solution of a particular treatment problem. Combinations may include
either several land-application techniques or land application together with
in-plant treatment. Increased felxibility of the overall system and increased
complexity of operation are side effects of treatment combinations which
should be considered.
D.4.a. Combinations of Land-Application Techniques
Combinations of land-application techniques may be desirable when dealing
with problems of differences in site characteristics (either within one large
site or between a number of sites), seasonal weather variations, or impact
minimization on a particular area. They may also be useful in adapting land
application to present land use; for instance, using a portion of the wastewater
to irrigate an existing golf course.
D.4.b. Combinations with Ih-Plant Treatment
Combinations of land application with in-plant treatment and receiving water
discharge may be advantageous in certain situations, especially if operating
costs of in-plant treatment are high. The most obvious advantages of this
type of combination can be seen in cold-weather regions where large storage
requirements may make land application an undesirable alternative. Partial
in-plant treatment could be used prior to land application in summer months,
with full in-plant treatment and surface water discharge used in the winter
months [l30j. Combinations for other purposes may be worth investigating.
Stormwater storage or treatment systems may also be integrated into
combined wastewater management systems.
D. 5. COMPATIBILITY WITH SITE CHARACTERISTICS
The success of a land-application system will depend upon the compatibility of
the selected treatment alternative to the project objectives, climate, and site
characteristics. To ensure compatibility, it is necessary to reevaluate the
alternative selection by proceeding stepwise through the flow chart. (Figure 1
in the Introduction), reviewing each consideration.
50
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Section E
DESIGN CONSIDERATIONS
Design considerations will differ greatly depending on whether irrigation,
infiltration-percolation, or overland flow is selected. The major considerations,
which are discussed in this section, include:
Loading rates
Land requirements
Crop selection
Storage requirements
Preapplication treatment requirements
Management considerations
Flexibility
Design reliability
The key issues involved in delineation of these design factors are identified and
discussed.
E. 1. LOADING RATES
To determine what characteristics of the wastewater will be limiting, balances
should be made for water, nitrogen, phosphorus, organic matter, or other con-
stituents of abnormally high concentration (as determined under I-B.4). On
the basis of those balances, a loading rate can be established for each parameter.
Each loading rate should then be used in calculating the required land area and
the critical loading rate is the one requiring the largest field area.
E. 1. a. Liquid Loading/Water Balance
The elements considered in a water balance are:
Effluent applied
Precipitation
Evapotranspi ration
51
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Percolation
Runoff
The interrelationships between the elements of the water balance for irrigation,
infiltration-percolation, and overland flow are discussed in the following
subsections.
Irrigation For irrigation systems, the amount of effluent applied plus precipita
tion should equal the evapotranspiration plus a limited amount of percolation. In
most cases, surface runoff from fields irrigated with municipal effluent will not
be allowed or must be controlled. The water balance will be:
Station + = Evapotranspiration + Percolation (2)
Seasonal variations in each of the above values should be taken into account. It is
suggested that this be done by means of evaluating the water balance for each
month as well as the annual balance. This method is illustrated in Example No. 1.
The value for design precipitation should be determined on the basis of a frequency
analysis of wetter than normal years (I-C. 2. a. 1.). The wettest year in 10 is sug-
gested as reasonable in most cases; however, it is prudent to check the water
balance using the range of precipitation amounts that may be encountered. For
purposes of evaluating monthly water balances, the design annual precipitation
can often be distributed over the year by means of the average distribution, which
is the average percentage of the total annual precipitation that occurs in each
month. Again, the range of monthly values that may be encountered should be
analyzed, especially for the months when the storage reservoir is full.
Evapotranspiration will also vary from month to month, however, the total for the
year should be relatively constant. The amount of water lost to evapotranspiration
each month should be entered in Equation 2.
Percolation includes that portion of the water, which after infiltration into the
soil, flows through the root zone and eventually becomes part of the groundwater.
The percolation rate used in the design should be determined on the basis of a
number cf factors (I-C. 2. c. 2.) including: soil characteristics, underlying geo-
logic conditions, groundwater conditions, and the length of drying period required
for satisfactory crop growth and wastewater renovation. The actual percolation
rate w?ll vary with soil temperature throughout the year; however, for design
purposes, it is often possible to assume a constant rate.
When irrigating in arid climates, it is necessary to remove the salts that accumu-
late in the root zone as a result of evaporation. Some amount of percolation is
necessary to accomplish this leaching. Ayers [7] has calculated the leaching
requirements for various crops, depending upon crop tolerances (I-E.3.) and
52
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total dissolved solids in the effluent. King and Hanks [75] have investigated the
possibility of controlling the quality of return flows by varying the timing of irri-
gation applications and have developed a mathematical model that may prove
valuable for situations in which TDS control is necessary.
EXAMPLE No. 1 - Determine the water balance for an
irrigation system.
Assumptions
1. The design precipitation is for the wettest year in 10, with average
monthly distribution.
2. Average monthly evapotranspiration rates are used; these are derived
from the Agricultural Extension Service.
3. The site is mostly flat and level.
4. The soil is a deep sandy loam.
5. The crop is coastal Bermuda grass.
6. Storage will be provided for a portion of the flow during the winter.
7. Runoff, if any, will be collected and stored for reapplication.
Solution Computations and results are presented in Table 5.
1. From a curve similar to Figure 2, the design annual precipitation for
the wettest year in 10 is found to be 13 in. (33. 0 cm). The precipita-
tion is distributed over the year on the basis of average distribution and
entered into Column 5 in Table 5 .
2. Average monthly evapotranspiration rates are entered into Table 5 in
Column 2.
3. On the basis of soil and geological evaluations, the design percolation
rate is determined to be 10 in. /mo (25 cm/mo) and entered into Col-
umn 3. The total water losses are determined by adding Columns 2 and
3 and entering the sum in Column 4.
4. Using Equation 2, the design precipitation is subtracted from the total
water losses to determine the amount of effluent to be applied (Column 6).
53
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Table 5. WATER BALANCE FOR EXAMPLE NO. 1
Water losses
Evapo-
transpiration,
Month in.
(1) (2)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Total
annual
0.7
1.5
3.1
3.9
5.2
6.5
7.0
6.5
4.4
3.9
1.5
0.8
45.0
Percolation,
in.
(3)
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
10.0
120.0
Total,
in.
(2) + (3) =
(4)
10.7
11.5
13.1
13.9
15.2
16.5
17.0
16.5
14.4
13.9
11.5
, 10.8
165.0
Water applied
Precipitation,
in.
(5)
2.3
2.3
2. 1
1.6
0.4
0.2
0.1
Trace
0.2
0.6
1.0
2.2
13.0
Effluent
applied,
in.
(4) - (5) =
(6)
8.4
9.2
11.0
12.3
14.8
16.3
16.9
16.5
14.2
13.3
10.5
8.6
152.0
Total,
in.
(5) >(6) =
(7)
10.7
11.5
13.1
13.9
15.2
16.5
17.0
16.5
14.4
13.9
11.5
10.8
165.0
Note: 1 inch = 2.54 cm
Comments
1. The maximum application of effluent will be less than 4 in./wk (io cm/wk)
and will occur in July.
2. If the effluent available equals effluent applied on a yearly basis, then
152 in. /yr divided by 12 months/yr equals 12. 7 inches of effluent would be
available each month (see Example No. 3).
3. Storage would be required for a portion of the flow for each month in which
the effluent available exceeded the effluent applied. In this case, storage
would be required from approximately mid November to mid April.
4. The annual liquid loading of 152 inches (386 cm) would place this land-
application system above the normal loading range for irrigation of 24 to
96 in. /yr (61 to 244 cm/yr).
5. The results obtained from this process would be utilized in the determi-
nation of .land requirements (I-E.2.) and storage requirements (I-E.4.).
54
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Infiltration-Percolation The elements of the water balance for infiltration-
percolation systems are the same as for irrigation (see Equation 2). Direct
runoff is not designed into such systems.
For low-rate applications involving evaporation-percolation ponds, evaporation
from the pond surface will be a significant factor. For these systems, the applied
effluent should balance the net evaporation (total evaporation minus precipitation)
plus the estimated percolation rate under saturated conditions. Saturated condi-
tions should be used because normally the soil surface is constantly inundated,
and the infiltration rate becomes significantly reduced over time. This reduced
infiltration rate subsequently limits the movement of water through the soil.
For higher rate systems and systems with intermittent applications, percolation
is the major factor, with evaporation accounting for 10 percent or less of the
effluent applied. Precipitation is significant in humid climates and is analyzed in
the same manner as irrigation, using a frequency analysis of the available data.
In arid climates, the precipitation should not be omitted, because it often all oc-
curs in a few winter months.
Overland Flow Typical loading rates range from 0.25 to 0.7 in./day
(0.64 to 1.78 cm/day) [125J. For year-round operation, the corresponding
amount of effluent applied would range from 8 to 20 ft/yr (2.44 m to 6.10 m/yr).
The water balance should be made mainly to determine the amount of runoff to
be expected. The water balance equation for overland flow is:
Design + Effluent = Evapo- + Percolation + R^^ (3)
precipitation applied transpiration
Design precipitation and evapotranspiration values are determined in the same
manner as for irrigation systems. Losses to percolation will generally be in the
order of 0.1 in. /day (0.3 cm/day) or less. Percolation rates should be estimated
under saturated or nearly saturated conditions. The runoff rate can be deter-
mined as the known values are entered into Equation 3. A typical range of runoff
values is from 40 percent (of the applied effluent plus precipitation) in the summer
to 80 percent in the winter [32, 56, 85].
E. l.b. Nitrogen Mass Balance
A total nitrogen balance is almost as important as a water balance, because
nitrate ions are mobile in the soil and can affect the quality of the receiving
water. On an annual basis, the applied nitrogen must be accounted for in crop
uptake, denitrification, volatilization, addition to groundwater or surface water,
or storage in the soil.
55
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E. l.b. 1. Total Annual Load - The total nitrogen load is necessary because all
forms organic, ammonia, nitrate, and nitrite interact in the soil. The
total nitrogen loading will be:
N = 2.7CL
(4)
where
N = annual nitrogen loading, Ib/acre/yr
C = total nitrogen concentration, mg/1
L = annual liquid loading, ft/yr
or:
N = 0.1CL (5)
where
N = annual nitrogen loading kg/ha/yr
C = total nitrogen concentration, mg/1
L = annual liquid loading, cm/yr
E. l.b. 2. Total Annual Crop Uptake - The nitrogen uptake of most crops has been
determined from greenhouse and field studies using fresh water for irrigation.
Typical uptake values are given in Table 6. It should be noted that nitrogen up-
take values may be higher when wastewater is applied instead of fresh water only
because more nitrogen is available.
For land-application systems, few nitrogen uptake values for crops currently
exist. It is expected that definitive values will be established in the near future.
Nitrogen uptakes for plants not listed in Table 6 can generally be obtained from
Agricultural Extension Service agents.
When more than one crop per year is grown on one field, the total nitrogen uptake
for the entire year should be determined. Nitrogen removal by crop uptake is a
function of crop yield and requires the harvesting and physical removal of the
crop to be effective.
E. l.b.3. Denitrification and Volatilization The extent of denitrification and
volatilization depends on the loading rate and characteristics of the wastewater to
be applied, and the microbiological conditions in the active zones of the soil.
Volatilization of ammonia will not be significant for effluents with a pH less than
7 or for nitrified effluents. For irrigation systems, denitrification is generally
56
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Table 6. TYPICAL VALUES OF CROP UPTAKES OF NITROGEN
Crop
Alfalfa
Red clover
Sweet clover
Coastal Bermuda grass
Corn
Cotton
Fescue
Milo maize
Reed canary grass
Soybeans
Wheat
Nitrogen
uptake,
Ib/acre/yr
155-220
77-126
158
480-600
155
66-100
275
81
226-359
94-113
50-76
References
54
54,
1
127
54
1
1, 30
1
1
32,
54,
54,
1
1
1
Note: 1 Ib/acre/yr = 1. 12 kg/ha/yr
of minor importance, depending upon the soil, the application rate, and the crop.
Hunt [67] suggests that denitrification may be a significant nitrogen removal
mechanism for overland flow systems because observed removals cannot be
accounted for solely by crop uptake.
For high-rate infiltration-percolation systems, denitrification is the only signifi-
cant mechanism of nitrogen removal from the system. By managing the hydraulic
loading cycle to create alternately anaerobic and aerobic conditions, Bouwer [20]
obtained up to 80-percent nitrogen removal as a combined result of ammonia
adsorption and denitrification during most of the period of inundation. Over a
4-year period the calculated removal was 30 percent at a loading rate of
21,000 Ib/acre/yr (23,450 kg/ha/yr). Without special management techniques,
overall nitrogen removal may only be 10 percent or less [82, 97].
E.l.b.4. Addition to Groundwater or Surface Water The soil mantle cannot
hold nitrogen indefinitely, although organic nitrogen can be stored in the soil
to a certain extent. The ammonium and organic nitrogen is ultimately converted
to nitrate nitrogen, which can leach out of the soil. Unless nitrogen is taken
up by crops and physically removed by harvesting, or the nitrates are converted
to nitrogen gas by denitrification, the nitrogen will appear eventually in the
runoff or percolate.
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E. 1. c. Phosphorus Mass Balance
Phosphorus is removed from percolating wastewater by fixation and chemical
precipitation. For irrigation, the phosphorus loading will usually be well below
the capacity of the soil to fix and precipitate the phosphorus. Typically, less
than 20 percent of the phosphorus applied is utilized by the crop and the remainder
stays in the topsoil [130]. Soil column tests are frequently conducted to deter-
mine the fixation capacities of the soil; however, the results of these tests should
be used with caution because long-term behavior and the effects of time cannot be
duplicated in a short-term test.
For overland flow systems, the removal mechanisms for phosphorus are crop
uptake, microbial uptake, and fixation by the soil. Because only a small portion
of the effluent applied infiltrates into the soil and crop uptake is small, removal
efficiencies are generally low, ranging reportedly from 35 percent at Melbourne,
Australia [76], to 50 percent at Ada, Oklahoma [1641. For infiltration-
percolation systems, fixation and chemical precipitation in the soil are respon-
sible for phosphorus removal. As with irrigation, the capacity of the soil to
remove phosphorus can be estimated from laboratory tests. This capacity can be
quite high even for sandy soils with relatively low fixation capacities. Bouwer
[21] reports 95 percent removal after 200 feet (61.0 m) of travel at a loading of
21,000 Ib/acre/yr (23,450 kg/ha/yr).
E. l.d. Organic Loading Rates
The average daily organic loading rate should be calculated from the liquid loading
rate and the BOD concentration of the applied effluent. Thomas [163, 165] has
estimated that between 10 and 25 Ib/acre/day (11.2 and 28.0 kg/ha/day) are
needed to maintain a static organic-matter content in the soil. Additions of
organic matter at these rates help to maintain the tilth of the soil, replenish the
carbon oxidized by microorganisms, and would not be expected to pose problems
of soil clogging. Higher loading rates can be managed, depending upon the type of
system and the resting period.
Irrigation - Using the range of 10 to 25 Ib/acre/day (11. 2 to 28. 0 kg/ha/day) of
BOD as a reference, the addition of 2 Ib/acre/day (2. 2 kg/ha/day) or less from
a typical secondary effluent applied for irrigation will certainly not pose a prob-
lem of organic buildup in the soil. When primary effluent is used, organic load-
ing rates may exceed 20 Ib/acre/day (22.4 kg/ha/day) without causing problems
[125J.
Resting periods are standard with most irrigation techniques. These periods
give soil bacteria time to break down organic matter and allow the water to drain
from the top few inches. Aerobic conditions are thus restored as air penetrates
into the soil. Resting periods for spray irrigation may range from less than a
day to 14 days, with 5 to 10 days being common [65]. The resting period for sur-
face irrigation can be as long as 6 weeks but is usually between 6 and 14 days
[130] . The resting period depends upon the crop, the number of individual plots
in the rotation cycle, and management considerations.
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Infiltration-Percolation Organic loading is an important criterion for infiltration
systems, because it is related to the development of anaerobic conditions. To
meet the oxygen demand created by the decomposing organic and nitrogenous
material, an intermittent loading schedule is required. This allows air to pene-
trate the soil and supplies oxygen to the bacteria that oxidize the organic matter
and ammonium.
Bouwer [20] reports BOD loadings of 45 Ib/acre/day (50.4 kg/ha/day) using sec-
ondary effluent and a liquid loading of 300 ft/yr (91. 4 m/yr). The application
cycle consisted of loading for 14 days, followed by 10 days of resting in the sum-
mer and 20 days of resting in the winter. Additional information on loading rates
and resting periods may be found in Wastewater Treatment and Reuse by Land
Application [125].
Industrial wastes have been loaded successfully on infiltration-percolation sys-
tems at 150 Ib/acre/day (168. 1 kg/ha/day) of BOD [125]. Thomas [165] reports
BOD loadings of 166 Ib/acre/day (186. 1 kg/ha/day) of septic tank effluent with
organic residues in the soil of less than 16 Ib/acre/day (17. 9 kg/ha/day). He
reports that this high loading can be used on sandy soils for extended periods
without resulting in the detrimental accumulation of organic residues in the soil,
and that during a 10-year period of operation, organic residues in the soil would
increase by no more than 3 percent of the weight of the top 6 inches (15. 2 cm) of
good mineral soil.
Overland Flow The limits of organic loading for the overland flow method are at
present undefined. High-strength organic wastes have been treated at BOD load-
ings of 40 to 100 Ib/acre/day (44. 8 to 112 kg/ha/day) [125]. Kirby [76] reports
that the grass filtration system at Melbourne, Australia, is loaded at 68 lb/acre/
day (76. 2 kg/ha/day) of BOD with a 96-percent removal efficiency. Thomas [164]
reports 92- to 95-percent removal of BOD at loadings of 14 to 18 Ib/acre/day
(15. 7 to 20. 2 kg/ha/day) with higher removals observed at the higher organic and
liquid loading rates. Higher organic loading rates can probably be used.
Because the organic matter is filtered out by the grass, litter, and topsoil, and
is reduced by biological oxidation, the organic content of the soil is not affected
substantially.
However, high organic loadings may limit treatment efficiency as a result of the
combination of effects of BOD and liquid loading on the creation of anaerobic con-
ditions. Because overland flow functions in a manner similar to a trickling filter,
intermittent dosing has been used successfully with 6 to 8 hours on and 6 to 18
hours off [125]. In Australia, continuous dosing has been used for up to 6 months
with the remaining 6 months for resting [76]. Provisions should be made to vary
the resting period, depending on climatic conditions, harvesting requirements,
and insect control considerations.
59
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E. 1. e. Loadings of Other Constituents Suspended and dissolved solids are the
two major types of remaining constituents of interest for land-application sys-
tems. Effects of these constituents vary with the type of system.
Large concentrations of suspended solids can clog the components of the distri-
bution system and reduce the infiltration rate into the soil. As a result, pre-
application treatment for suspended solids reduction may be necessary (see
I-E. 5). The organic fraction of the suspended solids when applied to the land is
degraded as described previously for BOD. The inorganic or mineral fraction of
the suspended solids is filtered out and becomes incorporated into the soil.
Dissolved solids in wastewater may be classified by the extent of their movement
through the soil. Chlorides, sulfates, nitrates, and bicarbonates move relatively
easily through most soils with the percolating water. These compounds can
therefore be leached with applications of wastewater or with rainfall.
Other dissolved solids, such as sodium, potassium, calcium, and magnesium,
are exchangeable and react within the soil so that their concentrations in the per-
colating water will change with depth. Other constituents, such as heavy metals,
boron, fluoride, and other trace elements or pesticides, may or may not be re-
moved by the soil matrix, depending upon such factors as clay content, soil pH,
and soil chemical balance. On the basis of the analysis of wastewater character-
istics (I.E.4) and the BPT requirements for groundwater protection, any
constituent suspected of having a limiting loading rate should be identified.
The loading rate of that constituent should then be calculated, and the resulting
land requirement (as discussed next under I-E.2.a.) should be compared to
the areas calculated for liquid or nitrogen loadings.
Irrigation Different wastewater constituents may be limiting in irrigation design,
depending on the objectives, crops, and climate involved. If crop yield or land-
scape enhancement is the major objective, Water Quality Criteria [176] and
Chapman [27] should be consulted to determine the optimum levels of various
elements for the particular plant and the possible effects of levels other than
optimum on plant quality and yield. Local farm advisers and Agricultural Exten-
sion Service agents may be contacted for evaluation of aniticipated special
problems.
When maximum effluent application is practiced, the crop selected should be able
to tolerate the particular wastewater at the loadings intended. The concentrations
of wastewater components will not usually limit the design loadings. provided there
is no probability of groundwater contamination by the percolate. If such a danger
exists, provisions such as underdrains should be considered,
Infiltration-Percolation Because of the high liquid loadings involved, the load-
ings of constituents in even low concentrations can be considerable. Soils used
for infiltration-percolation usually have little capacity to retain soluble salts and
may retain only portions of the heavy metals and phosphorus. The concentrations
of constituents, such as sodium, chloride, or sulfate, allowable in the renovated
water may affect the design by requiring special controls on the use of the reno-
vated water.
60
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The TDS and hardness of the percolating water may increase as a result of a
lowering of the pH of the water. Reid [132] reports a TDS increase of 11 percent
and a hardness increase of 30 percent at the 8-foot (2. 4-m) depth at Whittier
Narrows, California. It has been suggested that the pH drop from about 7. 0 to
approximately 6. 6 has been caused by nitrification [132]. Bouwer [20] reports
only a 4 percent increase in TDS, which he related to evaporation (3 percent) and
pH drop (1 percent). A pH drop, whether caused by nitrification or carbon dioxide
generated during BOD oxidation, can result in dissolution of calcium carbonate,
resulting in an increase in hardness and TDS.
Overland Flow Because a discharge of effluent that must meet or exceed treat-
ment criteria is usually involved in an overland flow system, the removal of vari-
ous wastewater constituents is important. The grass and litter in an overland
flow system serve to filter out suspended solids but have little effect on dissolved
solids. The loadings of most inorganic constituents will not limit the design of
overland flow systems, although some increase in TDS may occur if evapotranspi-
ration exceeds precipitation.
E. 2. LAND REQUIREMENTS
The total land area required includes allowances for treatment; buffer zones;
storage, if necessary; sites for buildings, roads, and ditches; and land for emer-
gencies or future expansion. If any on-site preapplication treatment, such as
screening, sedimentation, biological or chemical treatment, or disinfection, is
required, an allowance must be made for the land needed for these facilities. The
computation of land requirements is illustrated in Example 2.
E. 2. a. Field Area Requirement The field area is that portion of the land-
application site in which the treatment process actually takes place. It is deter-
mined by comparing the areas and is calculated on the basis of acceptable loading
rates for each different loading parameter (liquid, nitrogen, phosphorus, organic,
or others, based on BPT requirements for groundwater protection) and then
selecting the largest area. The loading parameter that corresponds to the
largest field area requirement would then be the critical loading parameter.
The field area requirement based on the liquid loading rate is calculated by:
Field Area (acres) =
where
Q = flowrate, mgd
L = annual liquid loading, ft/yr
61
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or:
_. ., , ... 315.6Q i<7\
Field Area (ha) = r^ \''
where
Q = flowrate, 1/s
L = annual liquid loading, cm/yr
For loadings of constituents such as nitrogen the field area requirement is
calculated by:
Field Area (acres) =
(8)
where
C = concentration of constituent, mg/1
Q = flowrate, mgd
L - loading rate of constituent, Ib/acre/yr
C
Field Area (ha) = 2±£Q (9)
where
C = concentration of constituent, mg/1
Q = flowrate, 1/s
L = loading rate of constituent, kg/ha/yr
C
Once the field area has been determined and the critical loading rate has been
identified, the resulting new loading rates for the other loading parameters should
be computed.
A distinction should be made between field area and wetted area. Field area
represents the area of the treatment system. The term wetted area refers to the
area to which liquid is directly applied, either the area covered by the diameter
of the spray or the area inundated by surface application. The significance of
this difference varies with the treatment method.
62
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Irrigation For spray irrigation, the wetted area may vary from 75 to 100
percent of the field area [131] . The percentage will depend upon the shapes of
the fields, the sprinkler discharge patterns, and the degree of spray overlap.
The highest ratio of wetted area to field area (0. 95-0. 99) occurs with flood and
ridge and furrow systems.
Infiltration-Percolation The wetted area should be nearly equal to the field
area for most infiltration-percolation systems. For constructed spreading
basins, considerable land may be lost in side slopes of the basin levees.
Overland Flow Terminology for overland flow hydraulic loadings and acreages
has not been standardized. Loadings are most often reported in inches per day
applied to the total field area. Field area represents the sum of the area under
sprays and the runoff area. The wetted area (area under sprays) is significantly
less than the field area for current designs using spray application.
Thomas [164] reports a wetted area of 25 percent of the field area, while wetted
areas of 40 to 45 percent of field areas have been reported for industrial
systems [125] . It should be noted that more than 25 percent of the land in
the Paris, Texas, overland flow system does not function as either wetted
area or runoff area but is undeveloped [56].
The length of the downhill slope beyond the spray perimeter will vary with the
climate, degree of treatment required, and the wastewater characteristics.
Thomas [164] reports 88 feet for comminuted domestic wastewater in Ada,
Oklahoma, with corresponding BOD removal efficiencies of 92 to 95 percent.
Gilde [56] reports that 95 feet (29.0 m) is adequate and 50 feet (15.2 m) is the
minimum for cannery wastewater with BOD removal efficiencies greater than
99 percent. A typical range would be one to two spray diameters beyond the
spray perimeter.
E. 2.b. Buffer Zone Allowance
Although there is little actual data concerning aerosols, there is considerable
concern about the effects of aerosol-borne pathogens. Therefore, application
of effluent by spraying may require buffer zones or other measures to ensure
that aerosols are contained on the site. Buffer zones ranging from 50 to
200 feet (15.2 to 61.0 m) wide have been reported [125], although requirements
for even larger buffer zones may exist. The size of the buffer zone that may be
required is dependent on a number of factors, and will generally be controlled by
the cognizant public health authority (I-F.2.d).
E. 2. c. Land for Storage
Irrigation and overland flow systems will generally require off-season or winter
storage. Storage may also be useful to equalize flowrates or to provide emer-
gency backup. The land required for storage lagoons or ponds may be consider-
able, especially in the northern states. Even in semiarid Abilene, Texas,
18 percent of the 2,019 acre (81? ha) irrigation farm is used for storage ponds [125]
63
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Infiltration-percolation systems incorporating spreading basins can usually
operate throughout the year, if the limiting loading rate was established for
winter conditions.
E. 2. e. Land for Future Expansion or Emergencies
Area for potential future expansion of a land-application system should be con-
sidered in the planning stage. If it is known that the adjacent land is planned
for development and will be unavailable for future use, the system should not
be referred to as a long-term solution. Often, it is prudent to obtain excess
land for emergency use. Such things as excessive rainfall, breakdown of pre-
application treatment operations, or natural disasters would constitute
emergencies.
EXAMPLE No. 2 - Calculate the land requirements for a
one mgd (43. 8 1/s) irrigation system.
Assumptions
1. The design liquid loading rate is 152 in./yr (386 cm/yr) from
Example No. 1, or 12. 67 ft/yr (3. 86 m/yr).
2. On the basis of the nitrogen balance, the nitrogen loading rate is
determined to be 650 Ib/acre/yr (740 kg/ha/yr). The average total
nitrogen concentration in the effluent from preapplication treatment
is 18 mg/1.
3. Concentrations of TDS and boron, and the SAR, are within an accept-
able range.
4. A buffer zone of 150 feet (45. 7 m) is required around the perimeter of
the site.
5. A 145 acre-foot (179, 000 cu m) storage reservoir (from Example
No. 3) of 10 feet (3. 05 m) average depth is included on the site. A
dike of 50 feet (15. 2 m) average width surrounds the reservoir.
6. A total of 4 acres (1.6 ha) is required for buildings, roads, ditches,
and other miscellaneous items.
7. Preapplication treatment facilities exist off-site.
Solution
1. The field area required, based on the liquid loading rate is computed
from Equation 6:
Field area = ft = 88. 3 acres' (35. 7 ha)
64
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2. The field area required, based on the nitrogen loading rate, is computed
from Equation 8:
. 84., acres ,34.Oh,,
A comparison of the two field area requirements shows that the liquid
loading rate is controlling; therefore the actual field area required is
88.3 acres (35.7 ha).
3. The area required for storage is:
14 *5 flCTf* "ft
Area of reservoir = IQ ft = 14-5 acres (5. 9 ha)
Assuming that the reservoir is rectangular with sides of 1, 000 and
650 feet (305 and 198 m), the area required for the dike is approximately
4 acres (1. 6 ha). The total area required for storage is then 18. 5
acres (7.5 ha).
4. The subtotal of the area required is:
Total Field Area 88.3
Storage 18.5
Buildings, roads, ditches, etc. 4.0
110. 8 acres (44.8 ha)
Assuming that this area is rectangular with sides of 3, 000 and 1, 600
feet (914 and 488 m), the area required for the buffer zone is approxi-
mately 34 acres (13. 8 ha). The total area required for the system is
then approximately 145 acres (59 ha).
Comments
1. The result of this process is only an approximation of the total land
requirements. A more detailed analysis would require that a prelimi-
nary layout or site plan be made so that topographic irregularities and
irregularities in the shape of the land parcel could be taken into account.
2. In this example, a factor of safety was not applied to the calculation
of field area, nor was extra land included for future expansion or
emergencies.
65
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E.3. CROP SELECTION
Proper crop selection is of great importance in the design of irrigation systems,
and to a lesser degree, of overland flow systems. It may also be of importance
for infiltration-percolation systems in which vegetation is grown on the infiltra-
tion surface.' Factors that should be considered include: (1) relationship to
critical loading parameter, (2) public health regulatious, («.
-------
Nutrient Requirements, Tolerances, and Removal Capabilities - Frequently, a
crop may be selected because of its removal capacity for essential nutrients,
particularly nitrogen and phosphorus. Although nutrient removal through crop
uptake and subsequent harvesting is most effective in irrigation systems, it is
also of significance in overland flow systems. If required, removal capacities
for many specific elements, such as boron, zinc, and copper, may be found in
Reed [130] for agricultural crops and Sopper [148, 150] for trees. Typical crop
uptake values of nitrogen are shown for a number of selected crops in Table 6.
Potential adverse effects on crops from high concentrations of nutrients should
also be considered, particularly when the quality of the crop is of great impor-
tance. Excess nitrogen, for example, may cause excessive plant height, late
maturation of fruit, and other problems in plants such as grapes [130]. Con-
sultation by the engineer with agronomists or Agricultural Extension Service
representatives may be necessary to determine nutrient requirements and toler-
ances, including seasonal variations.
Sensitivity to Inorganic Ions Crop selection must often be based on tolerance
to the various inorganic ions present in the applied wastewater or to those ions
that may build up in the soil after a number of years. Toxic levels of boron and
high salinity are the most common problems. The long-term buildup of various
heavy metals to toxic levels should be considered. The reduced response in
terms of percent yield decrement for various crops in arid and semiarid climates
to conductivity levels is shown in Tables 7 and 8. Additional data on tolerances
of various crops to certain elements and descriptions of toxic effects may be
found in Chapman [27] and references [1, 110, 125, 130, 176]. Suggested toler-
ance levels for heavy metals for various crops may be found in Melsted [99].
E. 3. b. Public Health Regulations
Various state public health regulations exist with regard to: (1) the types of
crops that may be irrigated with wastewater; (2) the degree of preapplication
treatment required for certain types of crops; and (3) the methods of applica-
tion that may be employed. As of 1972, at least 17 states had such regulations
[156], which vary widely in several respects. Generally, however, most states
prohibit the use of untreated sewage or primary effluent on vegetables grown
for human consumption, while some states allow irrigation of vegetables with
highly treated, oxidized, and disinfected effluent [125], Contradicting regulations
exist for the irrigation of pasturelands, recreational lands, and other areas
[160], State public health officials or other applicable authorities such as the
FDA should be consulted for existing regulations and guidelines. The literature
review of public health effects by Sepp [143] may be helpful to the engineer, par-
ticularly in states in which regulations are incomplete or do not exist.
E. 3. c. Ease of Cultivation and Harvesting
The ease of cultivation and harvesting of the selected crop may be of importance,
particularly for systems in which operation is to remain as simple as possible.
67
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Table 7. YIELD DECREMEMT TO BE EXPECTED FOR
FIELD CROPS DUE TO SALINITY OF IRRIGA-
TION WATER WHEN COMMON SURFACE
METHODS ARE USEDa
Crop
Barley
Sugarbeets
Cotton
Safflower
Wheat
Sorghum
Soybean
Sesbania
Rice (paddy)
Corn
Broadbean
Flax
Beans (field)
KCeb
e
6.7d
6.7
5.3
4.7d
4
3.7
2.7
3.3
3.3
2.3
2
1
0%
ECwb
5.3
4.5
4.5
3.5
3.1
2.7
2.5
1.8
2.2
2.2
1.5
1.3
.7
TDSb
3,392
2.880
2,880
2,240
1,984
1,728
1,600
1,152
1,408
1,408
960
832
448
ECe,
12
iod
10
8
7d
6
5.5
4
5
5
3.5
3
1.5
10%
ECw
8
6.7
6.7
5.3
4.7
4
3.7
2.7
3.3
3.3
2.3
2
1
TDS
5,120
4,288
4,288
3,392
3,008
2,560
2,368
1,728
2,112
2,112
1,472
1,280
640
ECe
16
13
12
11
10
9
7
5.5
6
6
4.5
4.5
2
25%
ECw
10.7
8.7
8
7.3
6.7
6
4.7
3.7
4
4.
3
3
1.3
TDS
6,848
5,568
5,120
4,672
4,288
3,840
3,088
2,368
2,560
2,560
1,920
1,920
832
ECe
18
16
16
14
14
12
9
9
8
7
6.5
6.5
3.5
50%
ECw
12
10.7
10.7
8
9.3
8
6
6
5.3
4.7
4. 3-
4.3
2.3
TDS
7,680
6,848
6,848
5,120
5,952
5,120
3,840
3,840
3,392
3,008
2,752
2,752
1,472
Maximum,
ECdw°
44
42
42
28
40
36
26
26
24
18
18
18
12
a. From Reference [7].
b. ECe means electrical conductivity of saturation extract in millimhos per centimeter (mmho/cm);
ECw means electrical conductivity of irrigation water (in mmho/cm). TDS in mg/L = ECw x 640.
c. ECdw shows maximum concentration of salts in drainage water permissible for growth. Use to calculate leaching
requirement (LR = ECw/ECdw x 100 %) to maintain needed ECe in active root area; Leaching Requirement (LR)
means that fraction of the irrigation water that must be leached through the active root zone to control soil salinity
at a specified level.
NOTE: Conversion from ECe to ECw assumes a three-fold concentration of salinity in soil solution (ECsw) in the
more active part of the root zone due to evapotranspiration. ECw x 3 = ECsw; ECsw + 2 = ECe.
d. Tolerance during germination (beets) or early seedling stage (wheat, barley) is limited to ECe about 4 mmho/cm.
Because the soil may often be saturated, the operation of farm machinery may;
be difficult or may cause excessive soil compaction, necessitating the selection
of a crop requiring little field maintenance. Selection of a perennial crop,Qyer>
an annual crop to avoid annual field preparation and planting may be worth ex-
amining.
E. 3. d. Length of Growing Season
The length of the growing season should be considered for potential crops, along
with seasonal variations in water requirements, and nutrient uptake. Storage
68
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Table 8. YIELD DECREMENT TO BE EXPECTED FOR FORAGE
CROPS DUE TO SALINITY OF IRRIGATION WATER&
Crop
Bermuda Grass
Tall Wheat Grass
Crested Wh. Grass
Tall Fescue
Barley (hay)
Perennial Rye
Harding Grass
Birdsfoot Trefoil
Beardless Wild Rye
Alfalfa
Orchard Gra&s
Meadow Foxtail
Clover
ECeb
8.7
7.3
4
4.7
5.3
5.3
5.3
4
2.7
2
1.7
1.3
1.3
0%
ECw
5.8
4.9
2.7
3.1
3.5
3.5
3.5
2.7
1.8
1.3
1.1
.9
.9
TDS
3,712
3,136
1,728
1,984
2,240
2,240
2,240
1,728
1,152
832
704
576
576
ECe
13
11
6
7
8
8
8
6
4
3
2.5
2
2
10%
ZCw
8.7
7.3
4
4.7
5.3
5.3
5.3
4
2.7
2
1.7
1.3
1.3
TDS
5,568
4,672
2,560
3,008
3,392
3,392
3,392
2,560
1,728
1,280
1,088
832
832
ECe
16
15
11
10.5
11
10
10
8
7
5
4.5
3.5
2.5
25%
ECw
10.7
10
7.3
7
7.3
6.7
6/7
5.3
4.7
3.3
3
2.3
1.7
TDS
6,840
6,400
4,672
4,480
4,672
4,288
4,288
3,392
3,008
2,112
1.920
1,472
1,088
ECe
18
18
18
14.5
13.5
13
13
10
11
8
8
6.5
4
50%
ECw
12
12
12
9.7
9
8.7
8.7
6.7
7.3
5.3
5.3
4.3
2.7
TDS
7 680
7,680
7,680
7,208
5,760
5,568
5,568
4,288
4,672
3,392
3,392
2,752
1,728
Maximum
ECdw
44
44
44
40
36
36
36
28
28
28
26
24
14
a. From Reference [7].
b. For explanation of abbreviations, see Table 7.
requirements and renovation efficiency at certain times of the year will be af-
fected by the choice. The advantages of perennials, which have fully developed
root systems at the beginning of the growing season, should be compared to the
advantages of annual crops that may have higher yields or economic return.
Cultivation of more than one annual crop per year may be possible.
E. 3. e. Landscape Requirements
The irrigation of landscape vegetation is a special case in which the vegetation
may already exist, or the choice may be limited to a few species of a particular
type. The most common type of vegetation is grass, especially for parks and
golf courses, where the condition of the turf is usually more important than the
renovation of wastewater. In cases in which landscape vegetation is among the
crop options, the reduction in the use of potable water and aesthetic and recre-
ational advantages should be balanced against the potential increased preappli-
cation treatment requirements and loading rate restrictions.
E.3.f. Forestland
Forests offer another crop option that requires special consideration. Most
commonly, existing forestlands can be used; however, new forest areas may be
69
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established, with species selected on the basis of their suitability to land appli-
cation. General information on the use of forestlands for land application is
contained in Cunningham [31] and Kazlowski [74]. Information on nutrient up-
take, growth responses, and general suitability is available for a limited num-
ber of tree species in references [1, 130, 148].
E.4. STORAGE REQUIREMENTS
In almost all land-application systems, storage facilities will be required. Re-
quired capacities may range from less than one day's storage to 6 months'.
The primary considerations in determining storage capacity are the local cli-
mate and the design period of operation; however, storage for system backup
and flow equalization should also be considered. The possibility of a secondary
use of the stored wastewater should be investigated.
E.4.a. Length of Operating Season and Climate
Most often, the storage requirements will be based on the period of operation
and the climate. Three different conditions can be encountered that necessitate
storage:
Winter weather requiring cessation of operation
Precipitation requiring the temporary reduction or cessation of
application
Winter weather requiring reduction of winter application rates
Generally, the most convenient method of determining the storage requirement
is by means of an extension of the monthly water balance (I. E. 1. a.). This
method is illustrated in Example 3 for a hypothetical system in which a portion
of the flow must be stored during the winter months when application rates are
reduced.
When cessation of operation resulting from winter weather is expected, storage
requirements should be based on the maximum expected period of nonoperatton.
The maximum period should be based on a frequency analysis of historical win-
ter weather data. Frost dates, periods of frozen ground conditions, and snow
cover should also be considered.
Temporary storage of wastewater may often be necessary when large amounts of
precipitation prohibit normal application rates, because of the danger of un-
wanted runoff, or the effects of hydraulic overloading on crops and renovation
efficiencies. The system should be evaluated to determine if excessive precipi-
tation can be retained on the fields or if application should be ceased. Precipi-
tation data should then be analyzed to determine the frequency of conditions
requiring temporary reduction or cessation of wastewater application and subse-
quent storage requirements.
70
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In cases where reduced application rates are necessary for the winter season,
an economic trade-off can be made between partial storage in winter versus
acquiring more land for winter application. For infiltration -percolation sys-
tems, cold weather may require only a reduction in the application rate
(I-E.2.C.).
In calculations of storage requirements, it may often be necessary to assume a
greater amount of precipitation than was assumed for the liquid loading evalu-
ation (I-E. 1. ). The amount of precipitation that must be assumed will depend to
a large extent on the degree of reliability required for the particular system
and the potential effects of reaching or exceeding the storage capacity in any
given year. In some cases, it may be prudent to apply a factor -of -safety to
the storage capacity (I-E. 9. e. ).
EXAMPLE No. 3 - Calculate the storage capacity requirements for
a one mgd (43. 8 1/s) irrigation system.
Assumptions
1. The design precipitation is the wettest year in 50, with average
monthly distribution.
2. The total monthly water losses, including evapotranspiration and de-
sign percolation are the same as in Example No. 1.
3. The actual field area is 88. 3 acres (35. 7 ha) (from Example No. 2).
4. The design year begins in October, at which time the storage reser-
voir is empty.
5. The flow of 1 mgd (43. 8 1/s) is constant throughout the year.
Solution The calculation of storage requirements per acre of field area
is shown in Table 9.
1. The effluent available per month is:
x 30. 4 day/mo x 36. 8 acre-in. /rag
88. 3 acre - ~
,, = 12. 7 in. /mo (32.3 cm/mo)
which is entered into Column 2 of Table 9.
2. From a curve similar to Figure 2, the design annual precipitation for
the wettest year in 50 is found to be 17. 0 in. (43. 2 cm). The precip-
itation is distributed over the year on the basis of average distribution
and entered into Column 3.
-, -, .. , ,
Eff. available = - - 88. 3 acre
71
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Table 9. CALCULATION OF STORAGE VOLUME REQUIREMENTS PER
ACRE OF FIELD AREA FOR EXAMPLE NO. 3
Month
(1)
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Effluent
available,
in.
(2)
12.7
12.7
12.7
12.7
12.7
12.7
12.7
12.7
12.7
12.7
12.7
12.7
12.7
Precipitation,
in.
(3)
0.8
1.3
2.9
3.0
3.0
2.7
2.1
0.5
0.3
0.1
Trace
0.3
0.8
Total,
in.
(2) + (3) =
(4)
13.5
14.0
15.6
15.7
15.7
15.4
14.8
13.2
13.0
12.8
12.7
13.0
13.5
Water
losses,
in.
(5)
13.9
11.5
10.8
10.7
11.5
13.1
13.9
15.2
16.5
17.0
16.5
14.4
13.9
AStorage,
in.
(4) - (5) =
(6)
-0.4
2.5
4.8
5.0
4.2
2.3
0.9
-2.0
-3.5
-4.2
-3. .8
-1.4
-0.4
Total
storage,
in.
(7)
0
2.5
7.3
12.3
16.5
18.8
19.7
17.7
14.2
10.0
6.2
4.8
4.4
Note: 1 inch = 2.54cm.
3. The total monthly water losses are taken from Column 4 of Table 5 and
entered into Column 5 of Table 9.
4. The monthly change in storage volume (Column 6 of Table 9) is com-
puted by subtracting Column 5 from Column 4.
5. The total accumulated storage (Column 7) is computed by summing the
monthly change in storage. ;.<
6. The maximum storage requirement is found to be 19. 7 in. (50. 0 cm) J
occurring in the month of April. This is converted to total storage
volume by:
Storage vol = 19' 7 ^ 83 acre = 145 acre ft (179,000 cu m)
TT
72
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Comments
1. In this example, it was assumed that the reservoir was empty at the
beginning of the winter season. In actual practice, this may often not
be the case. Consequently, it may be wise to assume an initial amount
of storage, or to assume back-to-back wetter^than-normal years if
storage volume is critical.
2. In some cases, it may be possible to ensure that the stored water is
completely withdrawn during the summer season for the storage design
year. This may be possible if design application rates are chosen con-
servatively or if extra land is included for emergencies.
3. For example purposes, the calculation of storage requirements was
conducted separately from the calculation of the water balance (Exam-
ple No. 1). It may often be convenient to combine these calculations.
4. In this example, a factor of safety was not applied to the total storage
volume.
E. 4,b. For System Backup
Storage requirements may be necessary for system backup or to preclude by-
passing of wastewater during periods of mechanical failure, maintenance, power
failure, or other problems. Storage for this purpose will add to the reliability
and flexibility of the system. For systems in which storage requirements are
otherwise small, requirements for system backup may be of significance. Con-
sideration should be-given to provision for gravity flow to storage backup facil-
ities under conditions of power failure. For additional considerations, the
technical bulletin on reliability [35] should be consulted.
E.4.C. ForFlowEqualization
Storage of wastewater for flow equalization may be necessary if daily fluctua-
tions in flow are significant and hinder the proper application of wastewater.
The sustained peak flow (I-B.l.) should be analyzed to determine the required
storage. Consideration of storage requirements for this purpose is normally
necessary only for systems for which no other storage requirements exist. In
most other cases, daily fluctuations in flow are easily absorbed in the larger
storage capacities required for other purposes.
E. 4. d. Secondary Uses of Stored Wastewater
After storage requirements have been determined, the possibility of secondary
use of the stored wastewater (prior to land application) should be investigated.
The areas of potential use are highly dependent on the quality of the stored waste-
water and the degree of preapplication treatment it has received. Perhaps the
most noteworthy of the potential uses is as industrial cooling water.
73
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E. 5. PREAPPLICATION TREATMENT REQUIREMENTS
The degree of treatment required prior to land application will depend upon a
number of factors, including: (1) public health regulations, (2) the loading
rate with respect to critical wastewater characteristics, and (3) the desired
effectiveness and dependability of the physical equipment. It is conceivable for
a system in which long-term winter storage is required that the degree of treat-
ment determined from the preceding considerations will not be adequate to pre-
vent odors from developing in the storage ponds. In such cases, costs for
increased treatment may be weighed against designing the storage ponds as
stabilization ponds to prevent odor generation.
Existing treatment facilities should also be evaluated, and other design criteria
particularly loading rates and crop selection should be reconsidered in light
of the preapplication treatment requirements.
E. 5. a. Public Health Considerations
Public health considerations, and regulations (in states where they exist), are
normally the most important factors in determining the required degree of pre-
application treatment. Factors that should be considered include:
Type of crop grown
Intended use of the crop
Degree of contact of the public with the effluent
Intended secondary use of the application area
Method of application
State regulations for treatment prior to irrigation differ considerably. For ex-
ample, the irrigation of certain crops to be eaten raw by humans may require
either secondary treatment with disinfection or advanced wastewater treatment
with disinfection, or it may be prohibited altogether [156]. State public health
officials should be consulted for existing regulations and guidelines. As an
illustrative example, the regulations for California are included in Appendix E.
In addition, it may also be helpful to contact the FDA or other appropriate agen-
cies, particularly when state guidance is lacking or not complete.
E. 5.b. Relationship to Loading Rate
The degree of preapplication treatment given the wastewater prior to application
will often have a considerable effect on the loading rate, and the final quality of
the renovated water. Of concern are those wastewater constituents that may tend
to limit the application rate, or for which the degree of renovation by land
74
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application is insufficient. Concentrations of suspended solids must often be
reduced to prevent soil clogging and land surface coating at design liquid loading
rates. Concentrations of other constituents - such as BOD, nitrogen, phosphor-
us, and various inorganic ions may need to be reduced to prevent the effects
of overloading and to ensure the required quality of the renovated water. In
many cases, liquid loading rates may be increased with no adverse effects on
the renovated water quality, if the concentrations of various constituents are
reduced.
E. 5. c. Relationship to Effectiveness of Physical Equipment
The effectiveness and dependability of the pumping and distribution system will
be largely affected by the degree of preapplication treatment, especially with
respect to reduction of suspended solids. High concentrations of grit and sus-
pended solids may cause: (1) the clogging of sprinkler nozzles, (2) the scoring
of pump parts, and (3) sedimentation in pipes and conduits. High-pressure
spray irrigation systems are normally the most susceptible to damage. Grease
and oil can also cause maintenance problems in valves, pipelines, and sprink-
lers.
E.G. MANAGEMENT CONSIDERATIONS
Management considerations should be kept in mind throughout the planning stage
of the project. Factors that should be considered include: (1) system control
and maintenance, (2) manpower requirements for operation and maintenance,
(3) monitoring requirements, and (4) emergency procedures and safeguards.
Detailed procedures should be incorporated into the Operation and Maintenance
Manual, which is discussed in Part m.
E. 6. a. System Control and Maintenance
The method and degree of system control and maintenance requirements should
be evaluated for each of the prospective land-application alternatives. System
control may be manual or partially automatic, depending on the complexity of
the system and the degree of variation expected in operating conditions. Most
systems will require direct control; however, for irrigation systems in which
effluent is supplied to independent farmers, control in possible only through
contract agreements. Maintenance requirements should be realistically assessed,
with emphasis on dependability of the system.
E. 6. b. Manpower Requirements
Manpower requirements are related directly to the methods of system control
and the maintenance requirements. The approximate number of personnel re-
quired should be determined, along with some indication of the necessary per-
sonnel qualifications and training requirements. Tchobanoglous [162], as shown
in Table 10, has estimated annual manhour requirements for hypothetical 1-mgd
75
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(43. 8 1/s) land treatment systems. Staffing requirements are also discussed
in references [49, 120].
Table 10. ESTIMATED ANNUAL MANHOUR REQUIREMENTS FOR
LAND-APPLICATION ALTERNATIVES WITH A DESIGN
FLOW OF 1.0 MGDa [162]b
Annual manhours
Category
Supervisory
Clerical
Laboratory
Yard
Operation
Maintenance
Total
Irrigation
416
104
416
208
1,040
1,248
3,432
Overland
flow
416
104
416
208
832
1,040
3,016
Infiltration-
percolation
416
104
416
208
520
416
2,080
a. 1 mgd = 43. 8 1/s
b. Labor requirements for preapplication treatment
are not included.
c. Includes preparation of reports.
E. 6. c. Monitoring R equirements
The system must be evaluated to determine monitoring requirements necessary
to ensure that proper renovation of wastewater is occurring and that environ-
mental degradation is not. In many states, monthly self-monitoring reports must
be submitted to the agency responsible for water pollution control. In addition,
monitoring may also be conducted for design refinement or research purposes.'
Generally, water-quality monitoring is important for each stage of the treatment
process, including the groundwater and any renovated water that is recovered
for reuse or discharge.
For many land-application systems, particularly those with significant deep
percolation rates, the monitoring requirement of primary importance in the
76
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planning stage will be that of groundwater. A network of monitoring wells, or
other monitoring devices, both on and off the site will often be necessary and
will require significant planning. Special agreements may need to be formulated
to drill and maintain access to off-site wells. Hydrogeologic considerations
pertaining to groundwater flow and the proper placement of monitoring wells
are discussed by Parizek [117].
E.6.d. Ernergency Procedure s
Emergency operating procedures should be considered at this point if serious
environmental damage could result from equipment breakdown, severe weather,
or power loss. An analysis should be made of the detrimental results that would
occur if power service were interrupted for various lengths of time.
E.7. COST-EFFECTIVENESS ANALYSIS
To properly select the best wastewater treatment alternative, a cost-
effectiveness analysis must be performed. To conduct such an analysis, de-
tailed cost estimates must be prepared. The cost estimates for each alternative
must be compared on an equivalent basis in terms of total present worth or
annual cost. For example, the total annual cost of an alternative would include
costs for operation, maintenance, and supervision and the amortized capital
cost.
Federal regulations on Cost-Effectiveness Analysis (40 CFR 35) should be con-
sulted, along with applicable state regulations for the proper methods of
conducting the analysis. Capital and operating cost considerations of importance
for land-application systems are discussed in the following subsections, while
social and environmental costs are discussed in the following section on
Environmental Assessment.
E.7.a. Capital Cost Considerations
Capital costs of importance for land-application systems include: acquisition of
land, easements, water rights procurement and rights-of-way; relocation of
buildings and residents; materials and construction costs for preapplication
treatment facilities, earthwork, transmission, distribution, collection (for over-
land flow and underdrained systems), and monitoring facilities; administrative,
legal, and engineering fees; startup costs; and interest during construction.
Special considerations for capital cost estimations for land-application systems -
including construction cost indexes, service life of equipment, and land costs
are discussed in the following subsections.
E. 7.a. 1. Construction or Other Cost Index Because costs are changing and
vary geographically, cost indexes published periodically are most useful in
determining current local costs. An estimate of the cost of construction of an
item can be made at one date and referenced to a cost index. To determine the
comparable present cost, the current index is located and the cost is updated
by multiplying by the ratio of the two indexes.
77
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A common index in the construction industry is the Engineering News Record
Construction Cost (ENRCC) index, which is weighted toward building and
heavy construction. For conventional treatment plants, a more appropriate
index is the EPA Sewage Treatment Plant index. For pipelines and drainage
systems, the EPA Sewer Construction Cost index can be used. All three indexes
are published in Engineering News Record.
E. 7. a. 2. Service Life of Equipment The service life of much of the equipment
used in land-application systems is highly variable. Standard service lives
for conventional treatment processes are presented in the Federal Regulations on
Cost-Effectiveness Analysis (40 CFR 35). Special service lives contained in
Table 11 have been suggested by the Sprinkler Irrigation Association [155], and
the University of Missouri Extension Division [l]. It should be noted that these
service lives are for standard irrigation equipment used typically for periodic
use during 4 to 6 months of the year. If irrigation machines are specially
designed for wastewater operations, they can be expected to attain similar
service lives. Therefore, factors particular to the system under consideration
that may affect the expected service life include the annual period of operation,
frequency of application, and wastewater characteristics.
E.7.a.3. Land Costs Costs for land can be a considerable part of the initial
capital cost, particularly for irrigation systems and for systems in relatively
developed areas. Alternative methods of acquisition, as discussed in the
previous section, should be compared on a cost-effective basis when praticable.
Costs related to land acquisition, such as the acquisition of easements and
rights-of-way and the relocation of residents, should also be included. In the
cost-effectiveness analysis, land shall have a salvage value at the end of the
planning period equal to its prevailing market value at the time of the analysis.
E. 7. b. Fixed Annual Costs
Annual costs for operation and maintenance should be included in the cost
analysis through the planning period (20 years). Fixed annual costs include
labor, maintenance, supplies, and monitoring. Inflation of wages and prices
should not be included unless significant changes in the relative prices of
certain items are anticipated (40 CFR 35).
E. 7. c. Flow-Related Annual Costs
Power is the major annual cost that depends on the annual quantity of wastewater
treated. Economic returns, such as those from the sale of crops and/or
renovated water, should also be considered., Costs of disposal should be
included if the crop or vegetation is not marketable.
E. 7. d. Nonmonetary Factors
Social and environmental factors and economic impacts are discussed in
Section F.
78
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Table 11. SUGGESTED SERVICE LIFE FOR
COMPONENTS OF AN IRRIGATION SYSTEM [155] and [l]
Component
Well and casing
Pump plant housing
Pump, turbine:
Bowl (about 50% of cost of pump unit)
Column, etc.
Pump, centrifugal
Power transmission:
Gear head
V-belt
Flat belt, rubber and fabric
Flat belt, leather
Power units:
Electric motor
Diesel engine
Gasoline or distillate:
Air-cooled
Water-cooled
Propane engine
Open farm ditches (permanent)
Concrete structures
Concrete pipe systems
Wood flumes
Pipe, surface, gated
Pipe, water works class
Pipe, steel, coated, underground
Pipe, aluminum, sprinkler use
Pipe, steel, coated, surface use only
Pipe, steel galvanized, surface only
Pipe, wood buried
Sprinkler heads
Solid set sprinkler system
Center pivot sprinkler system
Side roll traveling system
Traveling gun sprinkler system
Traveling gun hose system
Land grading"
Reservoirs0
Hours
16,000
32,000
32,000
30,000
6,000
10,000
20,000
50,000
28,000
8,000
18,000
28,000
Service life
or
or
or
or
or
or
or
or
or
or
or
or
or
Years
20
20
8
16
16
15
3
5
10
25
14
4
9
14
20
20
20
8
10
40
20
15
10
15
20
8
20
10-14
15-20
10
4
None
None
a. These hours may be used for year-round operations. The comparable period in years was
based upon a seasonal use of 2, 000 hr per year.
b. Some sources depreciate land .leveling in 7-15 years. However, if proper annual maintenance
is practiced: figure only interest on the leveling costs. Use interest on capital invested in
water right purchase.
c. Except where silting from watershed above will fill reservoir in an estimated period of years.
79
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E. 8. FLEXIBILITY OF ALTERNATIVE
Items that allow flexibility should be included in each element of the design.
Flexibility in the design of the system should generally be considered with
respect to: (1) changes in treatment requirements, (2) changes in waste-
water characteristics, (3) ease of expansion, (4) changes in land utilization,
and (5) technological advances.
E. 8. a. Changes in Treatment Requirements
The alternative plan should include provisions to upgrade water qualify to
meet more stringent treatment requirements. Various methods of upgrading
could include increased preapplication treatment and reduction of application
rates.
E.S.b. Changes in Wastewater Characteristics
In some cases, changes in wastewater characteristics may result from
changes in the water supply, new industries, or changes in the effluent
characteristics of existing industries. An assessment should be made of
the ability of the system to handle these potential changes, particularly in-
creases in certain critical wastewater constituents. Compensating modifica-
tions to the system, such as increased preapplication treatment or reduced
loading rates, should be identified.
E. 8. c. Ease of Expansion
Careful consideration should be given to the design capacity of the land-
application system and to the ease with which the system can be expanded.
Both planned stages of expansion and the need for expansion that might result
from unforeseen circumstances should be considered. All components of the
system that will be affected by expansion should be considered including:
Amount of land available
Storage capacity
Preapplication treatment capacity
Transmission facilities
The environmental impact of potential expansions should also be evaluated.
80
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E. 8. d. Changing Land Use
Future modifications to a land treatment system may be necessary because
of changes in adjacent land use. For example, a treatment system originally
situated in an agricultural or undeveloped area may, after a number of years,
become surrounded by residential, commercial, or industrial developments.
Requirements for odor control and aesthetics may become more strict and
unforeseen health concerns may arise. Modifications to the system, such as
additional buffer zones and stricter control procedures, may be necessary.
Treatment alternatives should be evaluated for effects that vary with different
uses of the surrounding land.
E. 8. e. Technological Advances
Future system modifications resulting from technological advances may be
possible. Wastewater treatment by land application is presently the subject
of a great deal of study and research. As a result, many new guidelines and
new techniques are anticipated. Advances may be possible in preapplication
treatment, application techniques, system monitoring, and in the knowledge
of soil-water-plant relationships.
E.9. RELIABILITY
The reliability and dependability of the system are critical, particularly if the
adverse effects of an operational breakdown or a poorly operating system
may be great. Areas of susceptibility, such as nozzle clogging, lack of
standby equipment, or lack of storage, should be identified and sufficient
safeguards employed whenever possible. A number of reliability features,
including factors-of-safety, backup systems, and contingency provisions,
should be included in the design of land-application systems (II-C. 9.). In
most cases, the requirement for these features should also be addressed in
the preliminary plan. For additional considerations, the EPA technical
bulletin on reliability [35] should be consulted.
E. 9.a. To Meet or Exceed Discharge Requirements
The reliability of the system should be assessed with respect to its ability
to meet or exceed present and future discharge requirements consistently.
This reliability should be assessed under both normal operating and potential
abnormal conditions.
E. 9.b. Failure Rate Due to Operational Breakdown
The possibility of system failure resulting from operational breakdown of
various components should be evaluated. The breakdown of the physical
equipment and preapplication treatment facilities and the temporary inability
of the soil to accept further application represent system failures. The con-
sequences'of system failure should be evaluated and additional safeguards,
including the use of backup systems, should be considered.
81
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E. 9. c. Vulnerability to Natural Disasters
The vulnerability of the system to natural disasters, such as earthquakes,
hurricanes, tornadoes, and floods, should be assessed. The probable conse-
quences should be considered, and safeguards, when they are feasible, should
be employed. Possible courses of action to deal with such events should be
included in the operation and maintenance manual.
E. 9. d. Adequate Supply of Required Resources
The reliability of the system should be evaluated with respect to the adequacy
of both the present and the anticipated future supply of required resources.
Resources that may require evaluation include: power, material for soil
additions, manpower, and chemicals required for preapplication treatment.
E. 9. e. Factors -of-Safety
One of the more significant reliability features that should be addressed in the
preliminary planning stage is the inclusion of factors-of-safety in the design
of various system components, such as flow capacities, field area require-
ments , and storage capacities. It is usually prudent to view the entire system
when evaluating the need for factors-of-safety, because the reliability of one
particular component often affects the degree of reliability necessary for
other components.
82
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Section F
ENVIRONMENTAL ASSESSMENT
The impact of the project on the environment, including public health, social,
and economic aspects must be assessed for each land-application alternative.
Environmental assessments are required for all federally funded projects,
and similar reports are required by many state and local governments. This
section is not intended to replace existing guidelines (40 CFR 6) for the prep-
aration of environmental assessments, but instead is designed to highlight
some of the important considerations particular to land application.
In accordance with existing guidelines, environmental assessment will gen-
erally consist of:
Description of the environmental setting
Determination of components affected
Evaluation of possible methods of mitigation of adverse effects
Determination of unavoidable adverse effects
Evaluation of overall and long-term effects
Environmental component interactions should be considered and measurable
parameters identified if possible.
F.I. ENVIRONMENTAL IMPACT
Environmental components that may be affected by land-application systems
include: (1) soil and vegetation, (2) groundwater, (3) surface water,
(4) animal and insect life, (5) air quality, and (6) local climate. Effects
on the soil, vegetation, and groundwater are normally the most critical, with
the effects on surface water being critical at times.
F. 1. a. Soil and Vegetation
The effects of land application on the soil and vegetation can be either bene-
ficial or adverse, with the overall effect most often being mixed. Effects on
surrounding land and vegetation may be brought about by changes in various
conditions, such as groundwater levels, drainage areas, and microclimates.
83
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Soil conditions, including drainage characteristics and levels of chemical
constituents, may be affected by land application. Infiltration and percolation
capacities may decrease as a result of clogging by suspended solids, although
proper management techniques including resting periods and soil surface
raking may help to mitigate this condition. Rates may also increase or
decrease as a result of changing chemical conditions, such as the pH and
sodium content of the soil. Long-term effects on the soil chemistry, such as
the buildup of certain constituents to toxic levels, may be critical in land-
application systems, Effects on soil conditions should be predicted initially,
and appropriate monitoring requirements should be defined. Various refer-
ences, particularly Thomas and Law [167]', may be helpful in predicting soil
effects.
The effects on vegetation are usually beneficial for a well-operated system.
Virtually all essential plant nutrients are found in wastewater and should
stimulate plant growth. Toxic levels of certain constituents in the soil, which
may reduce growth or render crops unsuitable for the intended use must be
evaluated [27]. Excess hydraulic loadings or poor soil aeration may also be
harmful to plant growth.
F. 1. b. Groundwater
The groundwater quality and level will be affected-by most land-application
systems. Exceptions would be many overland flow, underdrained, and
pumped withdrawal systems. Wastewater constituents that are not used by
the plants, degraded by microorganisms, or fixed in the soil may leach to the
groundwater. Nitrate nitrogen is the constituent of most concern; however,
heavy metals, phosphorus, organics, total dissolved solids, and other
elements discussed in I-B.4 may also be of significance.
Groundwater levels may be affected by land application, particulary for
infiltration-percolation systems. In turn, groundwater flow may be affected
with respect to both rate and direction of movement. The direction and effects
of the altered groundwater flow must be predicted, and appropriate monitoring
requirements defined.
F. 1. c. Surface Water
Surface waters may be affected directly by (1) discharge from an overland
flow, underdrained, or pumped withdrawal system, (2) interception of seep-
age from an infiltration-percolation system, or (3) undesired surface runoff
from the site. Both surface water quality and rate of flow may be influenced.
Changes in water quality will be regulated by federal, state, or regional
standards. Effects on surface water flow should be investigated both with
respect to possible increased and decreased rates of flow. Wastewater reuse
84
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systems, used to replace systems previously discharging to a surface water,
will result in decreased flows with possible adverse consequences to previous
downstream users, or existing fisheries.
F. 1. d. Animal and Insect Life
Treatment by land application may result in changes in conditions, either
favorably or adversly affecting certain indigenous terrestrial or aquatic
species. Beneficial effects, such as the increased nutritive value of animal
forage, should be compared to possible adverse effects, such as the disrup-
tion of natural habitat, for each species of concern. Little information exists
on this subject, but Sopper [148] reports some initial findings. The possi-
bility of insects or rodents acting as disease vectors is discussed separately
under Public Health Effects (I-F.2.b.).
F.l.e. Air Quality
Air quality may possibly be affected through the formation of aerosols from
spray systems and through odors. With aerosols, the primary concern is
with transmission of pathogens, which will be discussed further under
Public Health Effects. Odors are caused principally by anaerobic conditions
at the site or in the applied wastewater. Correction of these conditions is the
only permanent cure.
F.l.f. Climate
Land-application systems, particularly large irrigation or overland flow
systems, may have a limited but noticeable effect on the local climate. Air
passing over a site will pick up moisture and be cooled, resulting in a local-
ized reduction in temperature. Original conditions are normally regained
within a short distance from the site [125].
F.2. PUBLIC HEALTH EFFECTS
When evaluating the overall environmental impact of an alternative, special
consideration should be given to those effects that relate directly to the
public health. In many cases, state health regulations and guidelines serve
to protect against many of the effects. Public health effects that should be
considered include: groundwater quality, insects and rodents, runoff from
site, aerosols, and contamination of crops. Overviews of public health
effects that may be helpful are contained in references [13, 130, 143, 152].
F. 2. a. Groundwater Quality
The quality of the groundwater will be of major concern when it is to be used
as a potable water supply, particularly when an infiltration-percolation
system is planned. A sufficient degree of renovation will be required to
85
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meet the BPT requirements for groundwater protection. Nitrates are the
most common problem, but other constituents, including stable organics,
dissolved salts, trace elements, and pathogens should be considered.
Extensive monitoring and control practices must be planned.
F. 2. b. Insects and Rodents
Because of the possibility of contamination from pathogens in the wastewater,
the control of insects and rodents on a land-application site is more critical
than on a conventional irrigation site. Conventional methods of control will
normally be required for most pests.
Mosquitoes are a special problem because they will propagate in water stand-
ing for only a few days. Elimination of unnecessary standing water and
sufficient drying periods between applications are the most effective methods
of control.
F. 2. c. Runoff from Site
Applied effluent should not be allowed to run off the site except in systems
designed for surface ruroff (e.g., overland flow). The extent to which
runoff from storm events must be controlled depends upon the water quality
objectives of the surface water and the possible effects of such runoff on
water quality. Few data are available to assess storm runoff effects from
land-application sites.
F. 2. d. Aerosols
Generally, the danger of aerosols lies in their potential for the transmission
of pathogens. Aerosols are microscopic droplets that conceivably could be
inhaled into the throat and lungs. Aerosol travel and pathogen survival rate
are dependent on several factors, including wind, temperature, humidity,
vegetative screens, and other factors. Methods of reduction should be
employed to ensure that transmission of aerosols is minimized, with probable
travel under normal conditions being limited to an acceptable area. This
area should be determined on the basis of the proximity of public access.
Sorber [152] and Sepp [143] present discussions of this issue and discuss the
research on the subject.
Safeguard measures that may be employed against aerosol transmission
include:
Buffer zones around the field area
Sprinklers that spray laterally or downward with low nozzle
pressure
86
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Rows of trees or shrubs
Cessation of spraying or spraying only interior plots during high
winds
Combinations of the enumerated measures with adequate disinfection
F. 2. e. Contamination of Crops
The effect of effluent irrigation on crops, with regard to safety for consump-
tion, is a matter of some concern. Many states have regulations dealing
with the types of crops that may be irrigated with wastewater, degrees of
preapplication treatment required for various crops, and purposes for which
the crops may be used. The proposed California regulations are included in
Appendix E, and are offered as an example. Individual state health depart-
ments should be consulted, since regulations vary widely from state to state.
Additional information on the contamination of crops may be found in Sepp
[143], Rudolfs [135], and Bernarde [13], or by contacting the FDA or other
applicable agencies.
F.3. SOCIAL IMPACT
The overall effects of the proposed system should be evaluated in light of their
impact on the sociological aspects of the community. Included in the evalua-
tion should be considerations of: relocation of residents, effects on green-
belts and open space, effects on recreational activities, effects on community
growth, and effects on the quality of life.
F. 3. a. Relocation of Residents
The requirement for large quantities of land, particularly for irrigation and
overland flow systems, often necessitates the purchase of land and possibly
the relocation of residents. For federally funded projects, the acquisition
of land and relocation of residents must be conducted in accordance with the
Uniform Relocation Assistance and Land Acquisition Policies Act of 1970.
In such cases, the advantages of the proposed treatment system must be
weighed against the inconvenience caused affected residents, and then com-
pared with other alternatives.
F.3.b. Greenbelts and Open Spaces
Proposed treatment systems should be evaluated from an aesthetic point of
view and with respect to the creation or destruction of greenbelts and open
spaces. Disruption of the local scenic character is often unnecessary and
undesirable, while through proper design and planning, the beauty of the
landscape can often be enhanced. Reforestation and reclamation of disturbed
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areas, such as those resulting from strip mining operations, are possible
beneficial effects.
F. 3. c. Recreational Activities
The net result of the treatment system on recreational facilities should be
considered. Existing open space or parks may be disrupted; however, other
recreational areas may be created or upgraded. Irrigation of new parks or
golf courses and recreational use of renovated water are possibilities for
increasing the overall value of a proposed treatment system.
F. 3. d. Community Growth
The effects of a new treatment system may stimulate or discourage the growth
of a community, both in terms of economics and population. Often, improved
wastewater treatment service may allow new construction or expansion in the
service area. Such growth may consequently tax other existing community
services. The potential of the treatment system for affecting community
growth should be evaluated, and the subsequent effects on other aspects of the
community documented.
F.4. ECONOMIC IMPACT
An evaluation of the economic impact should include an analysis of all economic
factors directly and indirectly affected by the treatment system. Many factors
common to conventional systems apply; however, additional factors may be
applicable to various land-application systems. Possible additional factors
include:
Change in value of the land used and adjacent lands
Loss of tax revenues as a result of governmental purchase
Conservation of resources and energy
Change in quality of ground or surface waters
Availability of an inexpensive source of water for irrigation
The effect of the treatment system on the overall local economy should then
be appraised, especially with respect to financing and the availability of funds
for the long-term operation and maintenance of the system.
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Section G
IMPLEMENTATION PROGRAM
Selection of the best alternative must be based on an assessment of the cost-
effectiveness and the overall impact of the alternatives for wastewater
management. To ensure that the best system is selected by the decision
makers, all aspects of the alternatives should be made available for public
review and evaluation, including the engineer's recommendation. Re-
evaluation and modification of the plans may be necessary before a system
is selected and general acceptance is received. A long-range wastewater
management plan should be included with the implementation schedule.
G.I. PUBLIC INFORMATION PROGRAM
The establishment of an extensive public information program at the earliest
possible time is wise, especially when alternatives under consideration
may be controversial. Public.involvement to the maximum possible extent
should be sought, with feedback to planners and decision makers.
G.I.a. Approaches to Public Presentation
In many cases, public opposition to proposed land-application systems can be
related to lack of knowledge or understanding of the fundamentals involved.
Consequently, a well-planned information and education program is highly
desirable, and hi many cases, required. Effective presentation will usually
entail a combination of some or all of the following approaches.
G. 1. a. 1. Local Officials Close liasion should be maintained with all local
officials who may be directly or indirectly concerned with the project or its
effects. The maximum amount of useful information should be passed on to
these officials at the earliest possible time to ensure their thorough under-
standing and continuing support. Properly informed officials may in turn
become useful and integral members of the public information program
through public addresses and contacts with various citizen and special-
interest groups.
G. 1. a. 2. Public Hearings - Public hearings, which are required for most
projects, allow individuals and representatives of groups to speak and
present written statements of their viewpoints. These hearings should be
conducted in accordance with Public Participation hi Water Pollution Programs
(40 CFR 105).
Notification of the hearing should be extensive and in addition to advertise-
ments in the mass media should include notification by mail to all groups,
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agencies, and individuals who may have an interest. To ensure that key
decision makers are present, personal telephone invitations may be necessary.
The hearing should be recorded and should be followed up by resolution of
disagreements, corrections of deficiencies, additional hearings, or any
other measures that may be necessary.
G.I.a.3. Mass Media- The mass media, including local newspapers, radio,
and television may be helpful in dissemination of general information through
articles, special features, and interviews, Additionally, the mass media
should be utilized for notification and advertisement of hearings and other
public meetings.
G. 1. a. 4. Local Residents and Landowners - Local residents and landowners,
who may be displaced by the project, and those who are to be its neighbors
must be kept informed of current planning. Special information programs,
through letters, special meetings, and other means, are often necessary to
minimize opposition and to preclude possible legal conflicts that may result
from unwarranted assumptions and fears.
G. 1. a. 5. Special-Interest Groups - A wide variety of special-interest
groups - including sportsmen's clubs, conservation groups, and taxpayer
organizations - may be concerned with the project and its effects. Areas
of concern will be widely varied, but every effort should be made to anticipate
them and to address them at the earliest possible stage. Many well-informed
special-interest groups can be expected to add their support to the intended
project and may be valuable in helping to continue the public information
program.
G.l.b. Public Opinion
Public opinion may be expressed by various means, including: reaction at
public hearings, statements of various groups, letters, polls, and elections.
Expression of public opinion should be encouraged at an early stage so that
adequate consideration and response may be given to areas of concern.
Every effort should be made to ensure that all areas of concern are met with
reasonable responses based on a review of the project plans. Responses
may be either explanations and justifications or modifications to the portions
of the plan in question.
G. 2. LEGAL CONSIDERATIONS
Legal conflicts may sometimes be unavoidable in the implementation of land-
application systems, particularly in the areas of land acquisition and water
rights. To avoid later problems legal counsel may be desirable early in the
planning stage to outline legal constraints and ensure the overall legality of
the project. Possible areas of conflict should be anticipated and settled as
quickly as possible.
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G.3. REE VALUATION OF ABILITY TO IMPLEMENT PROJECT
Prior to the submission of the facilities plan, the entire project should be
reviewed and reevaluated. Considerations, such as public opinion, legal
conflicts, and method of financing including the possible need for bond elec-
tions, should be weighed against alternative concepts. The overall effect of
these considerations on the ability to implement the project should be assessed.
G.4. IMPLEMENTATION SCHEDULE
An implementation schedule is necessary to ensure orderly progress toward
completion of the project and to set up a long-range management plan. The
long-range plan must be formulated to ensure that the recommended courses
of action for wastewater management are carried out in an orderly manner
throughout the planning period. It is also imperative that the management plan
be designed so that technical and operational changes can be incorporated as
necessary during the planning period.
For construction purposes, the schedule should include goals for both begin-
ning and completion dates for various stages of the project. All key dates and
project stage sequences should be shown graphically for ease in understanding.
The implementation program should also document the steps in financing of
the system costs. Users charges and industrial cost recovery are required
for all projects receiving federal funds (40 CFR 35 regulations in the Federal
Register, August 21, 1973, and February 11, 1974). Costs that are eligible
for grant funding must be identified. Costs to be borne by the community
should be indicated on a per capita basis, with repayment and cost-sharing
by industries included. These are crucial issues in which the public will be
most interested.
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PART II
DESIGN PLANS
AND SPECIFICATIONS
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Section A
AGREEMENT WITH FACILITIES PLAN
When reviewing the design plans and specifications, the evaluator should have
a clear understanding of the facilities plan and its relationship to the design.
The engineer should include a statement with the design package concerning
agreement with the facilities plan especially with regard to:
Area for application
Critical loading rate
Degree of treatment
Storage volume
The design should conform as closely as possible to the facilities plan; however,
modifications may be necessary or desirable as the project is studied further,
and more data become available. Reevaluation of the plan, in whole or in part,
may also be necessary.
A.I. MODIFICATIONS
Modifications and refinement of the facilities plan are often necessary and can
occur for a variety of reasons. They may be the result of a pilot study, further
detailed site investigations, or a change in project goals.
Modifications to any one system component should be evaluated relative to their
effects on the entire system and on the other components. For example, a
decision to change the type of crop grown in an irrigation system may be based
on preapplication treatment considerations. The change in crops will, in turn,
^necessitate a reevaluation of such factors as loading rates, nutrient removals,
storage requirements, manpower requirements, and economic considerations.
To demonstrate expected treatment results in special cases, such as for overland
flow, pilot studies may be necessary. This should be a relatively rare occur-
rence for land-application approaches such as irrigation or infiltration-percolation
The extra cost of a pilot study and the subsequent delay of project implementation
must be well justified.
If pilot studies have been conducted, summaries of results should be required
either as a supplement to the facilities plan or as supporting material for the
design plans and specifications. These results may form the basis of modifica-
tions or support to the facilities plan.
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When departures from the original concept have been made for any reason,
justifications, new data, and computations should be required. This informa-
tion should be included in either a supplement to the facilities plan or as
supporting material with the plans and specifications, and should be reviewed
with respect to the applicable considerations from Parts I and II of this publi-
cation.
A. 2. RE EVALUATION OF FACILITIES PLAN
In some cases, a complete reevaluation of the facilities plan may be necessary
when changing conditions, new information, or unanticipated problems create
doubts as to the suitability of the system. Further modifications or reconsidera-
tion of previously eliminated treatment alternatives may be required. Areas
of primary concern include: changes in conditions and treatment requirements
that have occurred during the interim period and results from any pilot studies.
Changes in conditions and treatment requirements may be the result of new
federal or state regulations or changes in basin water-quality management plans
(40 CFR 131) or areawide wastewater treatment plans (40 CFR 35. 1050).
Areas that may be affected include: (1) both groundwater and surface-water
discharge requirements, (2) public health regulations with regard to pre-
application, crop selection, or application techniques, and (3) land-use or
zoning regulations.
Major problems with the proposed system may be identified during pilot
studies. Solution of these problems may be possible by changing design
criteria, process equipment, or management techniques. On the other hand,
the entire facilities plan may have to be reevaluated and another alternative
pursued.
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Section B
SITE CHARACTERISTICS
In this section, details concerning site characteristics that should be considered
when reviewing the plans and specifications are discussed with respect to topog-
raphy, soils, and geohydrology. In most cases, a considerable amount of data
on site characteristics will have been collected and analyzed during the planning
stage of the project and will have been included in the facilities plan (I-C.).
Frequently, the scope and degree of detail of this information is sufficient for
design purposes and it does not need to be repeated in material supplied to the
evaluator. In other cases, additional information and more detailed analyses
may be required. When this additional information is used as a basis for design,
its submission in the form of either a supplement to the facilities plan or as
supporting material with the plans and specifications should be required. Eval-
uation of this additional material should be with respect to considerations addressed
in both this section and in Section I-C.
B. 1. TOPOGRAPHY
A fairly detailed analysis of the topography of the site and adjacent land will have
been conducted during the planning stage. In the design stage, however, addi-
tional information may be required as plans are developed. Use of aerial or
ground surveys may be required to produce detailed plans for earthwork and site
preparation. The site topography, as altered by construction, earthwork, and
field preparation, should be analyzed for drainage patterns and erosion potential.
B. 1. a. Site Plan
In almost all cases, a set of large-scale site plans will be required. The scale of
the drawings will vary with the size and complexity of the project; however,
1 inch = 50 feet, with 2-foot contour intervals is considered reasonable for most
projects. Features that should be included are:
Topography of the site
Property boundaries
Application areas
Transmission and distribution systems
Buffer zones
Drainage systems and surface water bodies
Storage areas
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Preapplication treatment facilities
Monitoring points, wells, and springs
Roads, buildings, pumping stations, etc.
Additional plans may be necessary to show greater detail of certain features or a
greater amount of surrounding land. They will often be required for drainage
studies and for the exact location of transmission lines.
B. l.b. Effects of Adjacent Topography
The adjacent topography should be evaluated for its effects on the site, particu-
larly with respect to drainage. Adjacent land characteristics that may potentially
(1) add stormwater runoff to the site, (2) back up water onto the site, (3) provide
relief drainage, or (4) cause appearance of groundwater seeps, should be identified.
In most cases, the first two conditions are highly undesirable, and corrective
measures, such as interceptor ditches or drainage systems, must be employed.
B. 1. c. Erosion Prevention
The topography of the site and adjacent land should be evaluated for areas of poten-
tial erosion, and the plans should be checked for provisions for erosion control.
The effects of both applied wastewater and storm runoff should be considered.
Special consideration should be given to the period of construction and system
startup, when vegetative cover may be lacking or not fully developed. Erosion
control procedures are documented in a recent report for EPA [128].
B. 1. d. Earthwork Required
Earthwork details should be presented for both (1) field preparation, and (2) facil-
ities, such as transmission lines, storage, and roads. Earthwork required for
field preparation may include:
Clearing of existing vegetation and debris
Leveling, sloping, or grading of application area
Spreading or storage basin construction
Construction of dikes, levees, etc.
Drainage and collection ditches, and erosion-control measures
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The amount of earthwork required will be highly varied and will be dependent on
the type of system and the existing topography. For many systems, particularly
those employing overland flow, earthwork may be one of the largest construction
cost components. Where topsoil is shallow, it may be necessary to stockpile
topsoil for redistribution after the grading of underlying soil has been completed.
B. 1. e. Disposal of Trees, Brush, and Debris
A special consideration during construction and field preparation is the method of
disposal for trees, brush, debris, and other cleared material. This may present
a significant problem, particularly for projects in which large amounts of pre-
viously unused or uncultivated land are to be used. The most important concern
is that of the environmental impact, especially if disposal is to be accomplished
by burning. An acceptable method of disposal should be included in the
specifications.
B.2. SOIL
For some land-application systems, the analysis of soil characteristics conducted
during the planning stage will be sufficient for design purposes and reported mate-
rial need not be repeated with the design package. Additional information that may
be required for design is discussed in following subsections. Infiltration and per-
colation rates are discussed separately in the section on Design Criteria (II-C).
B. 2. a. Soil Maps
Soil maps should be included with design plans for land-application systems, un-
less previously submitted in the facilities plan. Although the generalized SCS soil
maps contain a large amount of useful data on soils, they may not be detailed or
specific enough for design purposes. The use of soil maps for the presentation of
soil data may be extremely helpful, particularly where soil characteristics are
varied over the site. Existing soil maps may be used, or maps can be prepared
showing variations in characteristics such as: (1) soil type, (2) infiltration and
percolation potentials, (3) physical and chemical characteristics, and (4) soil
depths.
B.2.b. Soil Profiles
A detailed description and analysis of the soil profile will frequently be necessary
for design purposes, particularly if a large amount of percolation is planned, and
where the effects of lower soil layers are of concern. Minimum soil profile
depths to be evaluated by the designer, as suggested earlier (I-C) are:
2 to 5 feet (0. 61 to 1. 52 m) for overland flow
At least 5 feet (1. 52 m) for irrigation
At least 10 feet (3.05 m) for infiltration-percolation
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The required data may be obtained from SCS soil surveys, borings or test pits,
or well-driller logs. If obtained from SCS surveys, the descriptions of the soil
profiles will generally include: (1) the location on the site where the profile was
determined, (2) mechanical classification, pH, salinity, and percent sodium for
each layer of soil encountered, (3) the depth of each layer, and (4) the percolation
rate expected. Additional soil analyses from the series of tests suggested in
I-C. 2. c. 1 may also be required. In many cases, soil profiles must be deter-
mined at a number of locations, particularly where soil characteristics are
varied over the site. Analysis of the underlying soil should be conducted pri-
marily with respect to those properties affecting renovation capabilities and
percolation potential (permeability for those soil layers that are to be saturated).
The need for soil amendments such as lime or fertilizer in the topsoil should be
determined.
B. 3. GEOHYDROLOGY
The extent to which geohydrologic conditions should be considered during design
will be dependent on the method of application to be employed and the type and
severity of conditions known to exist. Generally, a detailed analysis of the site
geology and groundwater conditions will be necessary for infiltration-percolation
and high-rate irrigation systems, where large amounts of percolating water may
greatly affect the groundwater. When potentially adverse conditions, such as
geologic discontinuities, perched water, and seasonally high water tables, are
indicated during the preliminary site investigation, additional analysis and con-
sideration may be necessary during design.
B. 3. a. Map of Important Geologic Formations
A map of the important geologic formations underlying the site will be necessary
where the formations may possibly affect the renovation of the percolating waste-
water or the groundwater flow. Formations and features that should be shown on the
maps or drawings that accompany the design package, when of significance, include:
Depth to bedrock
Lithology of bedrock
Outcrops
Glacial deposits
« Discontinuities, such as faults, joints, fractures, and sinkholes
When the underlying geologic conditions are relatively uniform, or when they are
of little significance a map will usually not be necessary.
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B.3.b. Analysis of Geologic Discontinuities
The presence of geologic discontinuities, such as faults, joints, fractures, and
sinkholes, is cause for special concern because short-circuiting of the percolating
wastewater may occur. In most cases, sites where geological formations contain
severe discontinuities should have been eliminated from consideration during the
preliminary site investigation; however, acceptable land-application systems may
be possible where: (1) short-circuiting of the percolate to the groundwater occurs
after sufficient renovation, and (2) the condition of the discontinuity is not expected
to worsen. The first condition can usually be met if a sufficient soil horizon
exists above the discontinuity. Suggested minimum depths of the soil horizon
above discontinuities are:
2 feet (0.61 m) for overland flow
5 feet (1.52 m) for irrigation
15 feet (4.57 m) for infiltration -percolation systems
With regard to the second condition, the probability that discontinuities will not be
aggravated as a result of the land-application system must be assessed. When the
site is underlain with limestone, discontinuities may well be aggravated. Existing
sinkholes may be enlarged and new ones created as a result of the percolating
wastewater.
B. 3. c. Groundwater Analysis
A detailed groundwater analysis will be necessary for design purposes, particularly
for infiltration-percolation and high-rate irrigation systems. Factors that should
be considered include: (1) existing quality of the groundwater and required quality
of the percolate with respect to the BPT requirements for groundwater protection [3],
(2) the extent of the recharge mound, (3) the need for underdrainage or pumped
withdrawal, (4) the probability of the groundwater reaching levels that may interfere
with efficient renovation (see I-C. 2. e. 1), (5) the effects of the system on direction
and rate of groundwater flow and, (6) the degree of monitoring required. Potential
adverse effects on the groundwater identified in the planning stage (I-F) should be
reviewed, and means of control employed in the design.
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Section C
DESIGN CRITERIA
The following factors should be considered in the design of a land-application
system:
Climatic factors
Infiltration and percolation rates
Loading rates
Land requirements
Application rates and cycle
Crops
System components
Flexibility
Reliability
It must be reemphasized that land-application system designs are site-specific
and that design criteria must be based on the conditions of the particular site.
In evaluating a design, the following points should be considered:
The validity of design assumptions
Compatibility with site conditions
Completeness and degree of detail
Ability to meet project objectives
In most cases, design criteria used as a basis for the plans and specifications
will have been included in the facilities plan (E-E); however, greater detail, re-
finements, and modifications will often be necessary. Submission of supporting
material for these refinements and modifications either along with the plans
and specifications or by means of a supplement to the facilities plan should be
required. This supporting material should be reviewed with respect to consid-
erations addressed in this section and Section I-E. , and then used as a basis
for evaluating the plans and specifications. Sample listings of design criteria
for irrigation, infiltration-percolation, and overland flow systems are included
in Appendix D.
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C. 1. CLIMATIC FACTORS
Design assumptions must be reviewed with regard to each climatic factor. For
example, if a particular system is to be designed so that no runoff from the site
results from a 5-year storm, the intensity of that storm should have been de-
termined and used as a basis for design. Climatic conditions must usually be
considered with respect to precipitation, temperature, and wind.
C. 1. a. Precipitation
Precipitation, including rainfall, snow, and hail, will affect a number of design
components such as: (1) liquid loading rates, (2) storage requirements, and
(3) drainage system requirements. Precipitation data that will normally be
required for design include:
Total annual precipitation
Maximum and minimum annual precipitation
Monthly distribution of precipitation
Storm intensities
Effects of snow
C. 1. a. 1. Total Annual Precipitation - The total annual precipitation used for
design purposes should normally be estimated from a frequency analysis of
precipitation data over the period of record (I-C.2.a). In most cases, precipi-
tation from a wetter-than-normal year must be assumed, particularly where
liquid overloading of the system may be a potential problem. The total annual
precipitation for the wettest year in 10 is suggested as reasonable for most
systems, although the wettest year in 50 or higher may be desirable for estimat-
ing storage requirements.
C. l.a.2. Maximum and Minimum Annual Precipitation In many cases, the
maximum and minimum annual precipitation on record will be of significance.
For example, a considerable difference between the design precipitation and the
maximum precipitation on record may require that special provisions for drain-
age be made. Minimum amounts of precipitation may be of interest for certain |
irrigation systems, where design liquid loadings are low and the applied waste-
water alone would not be sufficient for optimum vegetation growth. In such-, | n,
cases, a plan for reduced crop acreage or for supplemental irrigation water
should be included.
C. 1. a. 3. Monthly Distribution of Precipitation - The distribution of precipita-
tion over the year should be expressed as the amount of precipitation per month
for the design year. Seasonal variations in application rates and storage re-
quirements will be based on an analysis of the monthly distribution.
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C. 1.a.4. Storm Intensities Storm intensities, normally expressed in inches/
hour, must be estimated for the design of drainage and runoff collection sys-
tems. This estimation will normally be made on the basis of a frequency analy-
sis and a design storm event will be selected and analyzed for the amount of
runoff.
C. 1. a. 5. Effects of Snow In regions where accumulation of snow is probable,
the effect of snow conditions must be evaluated. Important data that may be re-
quired include: (1) total amount of snowfall, (2) maximum expected depth,
and (3) the period of snow cover.
C. 1. b. Temperature
Temperature, through its influence on various renovation mechanisms and on
plant growth, will affect liquid loading rates and the period of operation. Tem-
perature data that may be necessary for design include:
Monthly or seasonal averages and variations
Length of growing season
Period of freezing conditions
C. l.b. 1. Monthly Averages and Variations The range of temperatures that
prevail at the site should be expressed in terms of monthly or seasonal averages
and variations. In many cases, where cold weather may require a reduction or
cessation of application, design temperatures should be based on a frequency
analysis of colder-than-normal conditions.
C. l.b. 2. Length of Growing Season An estimation of the length of the growing
season will be necessary for irrigation and overland flow systems and for those
infiltration-percolation systems with vegetated basin surfaces. Because the
length of the season will vary with the crop, the Agricultural Extension Service
should be consulted.
C. l.b. 3. Period of Freezing Conditions The period when application 01 waste-
water must be reduced or ceased as a result of freezing conditions must be
estimated. Freezing conditions may include the period when the ground is
frozen or the period between the first and last frosts of the season.
C. 1. c'; Wind
For spray application systems, an analysis of the wind will be necessary for
design. Wind conditions that require a reduction or temporary cessation of
application should be determined with respect to velocity and direction. The
frequency and duration of those conditions should then be estimated by means
of a frequency analysis.
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C. 2. INFILTRATION AND PERCOLATION RATES
Infiltration and percolation rates are included in this section rather than the
previous one (Site Characteristics) because of their direct relationship to the
design of the system. Design rates must be determined for use in subsequent
design calculations such as application rates and drainage system requirements.
C.2.a. Design Rates
Design infiltration and percolation rates should be determined from data ob-
tained in the preliminary site investigation ([-C.2. c. 2) and from additional
studies where required. Other soil characteristics (II-B. 2) and geohydrologic
factors (II-B.3) must be evaluated for their effects on percolation rates. Con-
ditions that may be expected to periodically inhibit infiltration or percolation,
such as cold weather or prolonged periods of soil wetting, should be assumed
in the determination of design rates. Requirements for periodic drying or rest-
ing periods should be included.
C.2.b. Basis of Determination
The basis used to determine the design infiltration and percolation rates, and
the results of any studies or analyses involved, should be evaluated. Design
rates should be based on at least one or more of the following analyses or con-
sultation services:
Analysis by Agricultural Extension Service or soil specialists
Analysis of soil borings and profiles
Analysis of SCS soil surveys
From farming experience
From results of pilot studies
C.3. LOADING RATES
Loading rates for the liquid applied and the major constituents of the waste-
water will form the basis for the design determination of land requirements,
application rates, and crop selection (for irrigation and overland flow). Load-
ing rates computed in the preliminary planning stage (I-E. 1) should be reviewed
and possibly revised to reflect changes, in the wastewater characteristics or in
the application rates.
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C. 3. a. List of Loading Rates
Loading rates that form the basis of the design are to be included in the design
criteria (see Appendix D) for the specific land-application system.
Elements or constituents of concern should include any which may potentially
cause short- or long-term problems for the specific system, or whose concen-
trations in the renovated water may reach or exceed water-quality standards.
C.S.b. Critical Loading Rate
The loading rate identified in the planning stage as being critical (I-E. 2. a.) will
be used in the determination of the application area and other design factors,
such as crop selection. The critical loading rate should be highlighted with an
asterisk on the design criteria listings (Appendix D).
C. 4. LAND REQUIREMENTS
Land requirements must be identified for each of the following components:
Application area
Buffer zones
Storage
Preapplication treatment, buildings, and roads
Future and emergency needs
Land for each component should be designated on the site plan. Additionally,
methods of determination and calculations should generally be reviewed,
particularly those for the application area.
The land required for the direct application and treatment of the wastewater
will be calculated from the design critical loading rate as described in para-
graph I-E. 2. a. A distinction should be made between the wetted and field
acres where the distinction is significant, as is the case for all overland flow
and some irrigation systems. Individual plots or basins that are to be operated
as units in a rotation cycle should be identified and numbered.
C. 5. APPLICATION RATES AND CYCLE
The design application rates and the schedule of application periods should be
reviewed and related to the determination of land and storage requirements and
to the design of the distribution system (L-C. 7. d.). Factors and considerations
relating to their derivation are discussed below.
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C. 5. a. Annual Liquid Loading Rate
The design annual liquid loading rate (ft/yr) should be identified (H-C. 3.). All
application rates with respect to smaller units of time (e.g., in./wk) should be
derived from or be compatible with the annual loading.
C. 5.b. Length of Operating Season
The length of the operating system may vary from year-round for many
infiltration-percolation systems to as little as 5 or 6 months for some irriga-
tion systems.
C.S.c. Application Cycle
The application cycle, or the combination of application and resting periods,
should be defined in the form of an operating schedule. The length of the cycle
and the ratio of wetting to drying depends on site-specific factors (C-E. l.d.)
and may include seasonal variations. Common cycle lengths are:
1 week for irrigation, with a range from 2 days to 6 weeks
1 day for overland flow, with a range from 12 hours to 2 days
3 weeks for infiltration-percolation, with a range from a few days to
a month
C. 5. c. 1. Application Period and Rates- The application or wetting period of
the cycle should be listed along with the rate of application. Application rates
should normally be expressed in terms of quantity of wastewater applied per
cycle, and for spray applications the hourly rate should be listed. The latter
rate is particularly important for spray systems because high applications may
be damaging to the soil surface.
C. 5. c. 2. Weekly Application Rates When the application cycle is other than
one week, the additional inclusion of the average weekly rate may be helpful for
evaluation. Weekly rates are often used as standards for comparison of similar
systems and frequently appear in the literature.
C. 5. c. 3. Resting or Drying Period Resting or drying periods are necessary
to reestablish aerobic conditions. They should be included as an integral part
of the application cycle. Optimum resting periods range from one day or less
for some irrigation and overland flow systems up to 20 days for some
infiltration-percolation systems. In many cases, longer resting periods are
required during the winter months.
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C. 5. c. 4. Rotation of Plots or Basins To maintain continuous operation and
a steady usage of effluent, it is usually advisable to subdivide the application
area into a number of independent plots or basins. Wastewater can then be
applied to a portion of the area while the remainder is rested or dried. Pro-
vision for plot or basin rotation should be included in the plans.
C. 6. CROPS/VEGETATION
A description of the crops or vegetation to be grown will be required in the
facilities plan for all systems in which vegetation is to be an integral part of
the treatment system. This includes all irrigation and overland flow systems,
and those infiltration-percolation systems in which the infiltration surfaces are
to be vegetated. Evaluations of potential crops that were conducted during the
planning stage (I-E. 3.) should be reviewed, and important crop characteristics
and requirements that were used as a basis for design should be noted. When
applicable, the following items should be considered:
Compatibility of the crop with site characteristics and design loading
rates
Nutrient uptake
Cultivation and harvesting requirements
Suitability for meeting health criteria
C. 7. SYSTEM COMPONENTS
A large portion of the plans and specifications will be devoted to the system
components, such as:
Preapplication treatment facilities
Transmission facilities
Storage facilities
Distribution system
Recovery system
Monitoring system
Design considerations and parameters developed in the planning stage should be
reviewed when applicable. Detailed plans for each component will be required
and should be evaluated with respect to the considerations listed at the beginning
of this section.
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C. 7. a. Preapplication Treatment Facilities
Detailed plans of the preapplication treatment facilities will be necessary in
almost all cases, except those few in which preapplication treatment is not re-
quired or existing facilities have been determined to be adequate. In many
cases, plans for additions or modifications to existing facilities may be all that
are required. In all cases, the expected treatment performance of the facilities
must be evaluated in light of the requirements established in the planning stage
(I-E.5.).
C.7.b. Transmission Facilities
Detailed plans of the transmission facilities to the site, including piping and
pumping facilities, will be required. They should be designed and reviewed in
accordance with conventional engineering standards, because they will rarely
differ from transmission facilities designed for conventional treatment systems.
Consideration must be given to factors such as adequate cover over the pipe for
protection, and provisions for flexible joints where the pipe is attached to rigid
structures. In addition, consideration must also be given to the purchase and
control of easements.
C. 7.c. Storage Facilities
In almost all cases, some sort-of storage facilities will be necessary, and de-
tailed plans for them will be required. If storage is to be provided for winter
flows and storage requirements are high, construction of storage facilities will
often be one of the major design components. The design volume should be
based on the storage requirements determined during the planning stage
([-E.4.). The plans should be evaluated with respect to capacity and control of
potential problems, such as the growth of unwanted aquatic life, odors resulting
from anaerobic conditions, and with respect to structural considerations, such
as embankment slope stability. Storage facilities must include pump-back pro-
visions and adequate freeboard, and-it may possibly be necessary to seal them
to prevent percolation, depending upon groundwater conditions.
C. 7. d. Distribution System
The distribution system may vary in complexity from systems employing simply
gravity flow to infiltration basins to highly complex fixed spray irrigation sys-
tems. Standard texts on irrigation [155, 184] provide much information on the
design of all types of distribution systems, which may be useful to the reviewer.
Potential problems, such as the clogging of nozzles with suspended solids and
the susceptibility of above-ground piping to damage by farm machinery, should
be anticipated, and mitigation provisions reviewed.
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Spray Systems Distribution for spraying is through pressure pipes or laterals
that run from the transmission main into the field. Spray distribution systems
may be solid set, buried; solid set, portable; mechanically-moved laterals,
such as the side-roll wheel or end-tow type; or continuously moving units such
as center pivot systems [114]. Sprinkler irrigation handbooks [114, 115, 155]
should be consulted for hydraulic design information. Special emphasis should
be given to the potential problems associated with risers, which are often sus-
ceptible to damage from a number of causes.
Surface Distribution Systems For flood or ridge and furrow systems, distri-
bution may be by means of open ditches, buried pipe with riser outlets, or
gated pipe. More detailed information may be found in Zimmerman [184].
Drainage of Lines Drain valves are necessary for most distribution systems
to prevent (1) anaerobic conditions from occurring during nonapplication
periods, and (2) freezing and breaking of pipes in cold climates. Drain
valves should be located at all low points in the system with gravel or tile
drains to accept the draining water.
System Controls A schematic diagram of system controls including piping,
pumping, valves, timers, and alarms is necessary. Valve operation and con-
trol may be automatic or manual or provisions may be made to operate under
either type of control.
C.7.e. Recovery System
Detailed plans should be submitted of any recovery system that is to be em-
ployed, such as: underdrainage, pumped withdrawal, or collection of runoff
from overland flow systems. It should be evaluated with respect to recovery
objectives, site characteristics, and liquid loading rates. Much useful infor-
mation on the design of recovery systems may be found in Drainage of Agri-
cultural Land [38], and in Bouwer [18, 19] .
In cases in which natural drainage channels traverse the site some runoff
control features may be required. For irrigation systems these features would
be designed for system protection and realiability. Features could entail small
dams, reservoirs, or diversion structures to collect or divert partially treated
effluent and prevent it from entering surface waters. The extent to which
runoff resulting from storms must be retained depends upon the water quality
objectives for the surface water, nonpoint source discharge control practices
in the hydrologic basin, and the nature and magnitude of the environmental
degradation that might result from the discharge.
CL7.f. Monitoring System
Some form of monitoring system will be required in all cases and should be
described in detail in the Operation and Maintenance Manual. Plans for physical
facilities, such as monitoring wells, sampling taps, and metering equipment,
however, should be included in the design and should reflect the monitoring re-
quirements specified in the preliminary plans (I-E. 6. c.).
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C. 8. DESIGN FLEXIBILITY
The design plans and specifications should be evaluated for flexibility with
respect to:
Provisions for system expansion
Provisions for system modification
Interconnections and partial isolation
Specific flexibility features identified in the wastewater management plan
(I-E. 8.) should be incorporated in the design.
C. 8. a. Provisions for System Expansion
Provisions for both planned and unplanned expansion should be incorporated in
the design. Staged construction will often be employed over the life of the sys-
tem to provide for planned expansion. In other cases and for unplanned expan-
sion, components may be designed for additional capacities or so that their
capacities may be easily increased. Special consideration should be given to
critical components such as: land availability; and storage, preapplication
treatment, and transmission capacities -which maybe easily expandable only
up to a certain limit.
C. 8.b. Provision for System Modification
Various modifications to the system can usually be expected to occur during the
life of the system and if possible, should be anticipated in the design. Gener-
ally, these modifications will be the result of:
Knowledge gained through operating experience
Changes in conditions or treatment requirements
Technological advances
Design factors, such as loading rates, and physical equipment, such as pre-
application treatment and distribution facilities, are among the items that may
be subject to modification.
C. 8. c. Interconnections and Partial Isolation
Features, such as interconnections and partial isolation systems, that may add
to the flexibility of operation should be included in the design when practicable.
Various interconnections within and between the transmission system, pre-
application treatment facilities, storage facilities, and distribution system are
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necessary so that components can be isolated for repair or maintenance. The
design should also include provisions to allow the operator to modify operating
procedures for special conditions, and apply effluent to certain areas only.
C. 9. RELIABILITY
The Technical Bulletin on Design Criteria for Mechanical, Electrical, and
Fluid Systems and Component Reliability [35] establishes minimum standards
of reliability for three classes of wastewater treatment works. The classes
are related to the consequences of degradation of the effluent quality on the re-
ceiving navigable waters. Class I involves discharge to navigable waters that
could be permanently or unacceptably damaged by effluent that was degraded in
quality for only a few hours. Reliability measures for this class include backup
requirements for most unit processes. Class II relates to navigable waters
that would not be permanently or unacceptably damaged by short-term effluent
quality degradations, but could be damaged by continued (on the order of several
days) degradation. Class III involves navigable waters not otherwise classified
as Reliability Class I or II [35].
Land-application systems that produce an effluent with a point-source discharge
would have to attain a reliability commensurate to that of conventional treat-
ment and discharge systems discharging to Class I, II, or III navigable waters.
The degree of reliability required of land-application systems will depend on the
severity and consequences of environmental degradation or health effects
(I-F. 1 and F.2). The California standards (Appendix E) relate reliability
measures for irrigation systems to the degree of public contact with the treated
effluent and the nature of the crop grown.
Various means of ensuring the reliability of the system, including factors of
safety, backup systems, and contingency provisions, are discussed in the fol-
lowing paragraphs. An important additional reliability factor is the proper
operation and maintenance of the system, which is discussed in Part HI. Gen-
eral reliability requirements for all treatment systems are included in Fe'deral
Guidelines for Design, Operation and Maintenance of Waste Water Treatment
Facilities [50].
C. 9. a. Factors-of-Safety
Reasonable factors-of-safety must be included in design components whose
normal operation limits, if exceeded, might result in serious adverse effects
or impairment of system efficiency. Components that may require factors-
of-safety in their design include: loading and application rates, and the capaci-
ties for storage, transmission, and preapplication treatment. The magnitude
of the factors-of-safety to be employed will vary with the system and will depend
on a number of factors, such as: the severity of potential adverse effects, and
degree of certainty of design assumptions. When employed, they should be
indicated and justified by the engineer.
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C. 9.b. Backup Systems
Backup systems or standby units must be provided for critical elements of the
system to preclude system failure resulting from:
Loss of power supply
Equipment failure
Failure of a preapplication treatment unit
Maintenance requirements
Elements that should be provided with backup systems include power sources,
pumping facilities, and preapplication treatment units (particularly chlorina-
tors). Interconnections and flexibility of pumping and piping to permit re-
routing of flows will often be necessary also.
C. 9. c. Contingency Provisions
Provisions must be made in the design for specific, unusual, or emergency
conditions that may occur at the site, such as:
Equipment or unit failure
Natural disasters (floods, earthquakes, etc.)
Severe weather
Unexpected peak flows
The system must be evaluated to determine whether it can be operated satis-
factorily under these conditions. Provisions should be included to allow the
resumption of normal operation, such as emergency pumping or additional
storage capacity.
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Section D
EXPECTED TREATMENT PERFORMANCE
The expected treatment performance must be evaluated with respect to both
(1) removal efficiencies for major constituents, and (2) remaining concen-
trations in the renovated water. It should be predicted realistically based on
the method of application, degree of preapplication treatment, site character-
istics, and design parameters. Fluctuations in performance during loading
cycles or as a result of seasonal climatic variations, should be considered.
D. 1. REMOVAL EFFICIENCIES FOR MAJOR CONSTITUENTS
The removal efficiencies, or the percentage reduction in concentration of each
of the major wastewater constituents must be estimated. Removal efficiencies,
based on data derived from operating systems, that may be expected for well-
designed and properly maintained, irrigation, overland flow, and infiltration-
percolation systems are given in Table 12. Predicted efficiencies should be
estimated for each constituent, and a description of the removal mechanism,
particularly for constituents such as nitrogen, where removal efficiencies are
highly variable, should be included either in the project report or a supplement.
The values in Table 12 are presented for evaluation, not design purposes. De-
sign values must be developed on a case-by-case basis. Factors such as chang-
ing climatic conditions or changing operating procedures that may cause fluc-
tuations or permanent changes in the removal efficiencies should be identified.
Expected long-range changes, such as those resulting from exhaustion of the
ion-exchange capacity of the soil, should be identified and provisions made for
soil amendment additions, upgrading or preapplication treatment, or cessation
of application.
Table 12. REMOVAL EFFICIENCIES OF MAJOR
CONSTITUENTS FOR MUNICIPAL LAND-APPLICATION SYSTEMS
Removal efficiency, %
Application method
Constituent
BOD
COD
Suspended solids
Nitrogen (total as N)
Phosphorus (total as P)
Metals
Microorganisms
Irrigation
98+
95+
98+
85+
80-99
95+
98+
Overland
How
92+
80+
92+
70-90
40-80
50+
98+
Infiltration-
percolation
85-99
50+
98+
0-50
60-95
50-95
98+
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Expected removal efficiencies must be determined for each individual case
based on the wastewater characteristics, site characteristics, and specific
design features. For example, consider phosphorus removal for an overland
flow system. Assuming that the total concentration after preapplication treat-
ment is known, what removal efficiency can be expected ? Without pilot work
to serve as a basis for estimation, a review of the literature must be used.
Representative reports dealing with phosphorus removal include those by Law
[84], Kirby [76], Thomas [164], and Hunt [67]. To properly assess the ex-
pected removal, comparisons must be made of the systems described in the
literature with the system in question on the following points:
Total concentration applied to the land
Total annual loading, Ib/acre/yr
Percentage of applied wastewater appearing as runoff
Soil type
Evapotranspiration
Amount of percolation
Crop type and uptake of phosphorus
Was the crop removed from the field ?
Application cycle
Length of the runoff slope
Amount of rainfall during period of measurement
Obviously, few of the conditions will be comparable so that some engineering
judgment will be required. Each removal mechanism (EI-E. 1. c.), such as
crop uptake, microbial uptake, and fixation by the soil, must be investigated
and the expected removals estimated.
The process of determining expected removal efficiencies can often be complex.
The degree of detail expected in deriving these estimates will depend on the im-
pact of the constituent on the environment and the concentration required in the
renovated water.
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D.2. REMAINING CONCENTRATIONS IN RENOVATED WATER
The remaining concentrations of the major constituents in the renovated water
should be determined from concentrations of the wastewater applied and the
predicted removal efficiencies. They should be compared to the concentra-
tions required for the receiving waters, either groundwater or surface water,
or to requirements for further reuse. Generally, to be acceptable, the con-
centrations should be well within the limits of stated requirements.
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PART III
OPERATION AND
MAINTENANCE MANUAL
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Section A
EPA - CONSIDERATIONS FOR PREPARATION OF QPEEATION
AND MAINTENANCE MANUALS
Operation and maintenance manuals should generally be prepared in accord-
ance with the suggested guidelines presented in the EPA publication Consider-
ations for Preparation of Operation and Maintenance ManualsJ 61], which is
hereafter referred to as the "Considerations Manual. " ThejTshould be
reviewed and evaluated by means of the checklist included in the Considerations
Manual, and with regard to special considerations for land-application sys-
tems presented in this and the following sections.
Discussion of the information that should be included in operations and
maintenance manuals for land-application systems is presented in the follow-
ing subsections by suggested chapter titles. Detailed discussion of information
concerning operating procedures, monitoring, and impact control is con-
tained in Sections B, C, and D. The format suggested herein and in the
Considerations Manual is intended to be flexible and may be modified to fit
the particular system at hand. The uniqueness of many land-application
systems must be reflected in the operation and maintenance manuals, and
greater-than-normal emphasis must be placed on their preparation, especi-
ally in the explanation of the unique aspects.
A.I. INTRODUC TION
The introduction to an operation and maintenance manual should include:
A manual user guide
« Summaries of operation and managerial responsibilities
Description of the treatment concept employed and treatment
requirements
Explanation of flow patterns
A discussion of the contents of the introductory chapter and examples showing
the scope of information that should be included is contained in the Consider-
ations Manual.
The description of treatment requirements should highlight requirements
with respect to groundwater including meeting requirements of BPT for
groundwater protection, as well as effluent limitations for that portion of
the renovated water that may be recovered.
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In many cases, a brief summary of basic land-application principles may be
helpful, particularly for users of the manual who have had experience only
with conventional treatment systems.
A. 2. PERMITS AND STANDARDS
The chapter on permits and standards should include:
Discharge permit and permit requirements (for point-source
discharges)
Reporting procedures for spills of raw or inadequately treated
sewage
Water-quality standards
The suggested contents of the chapter are discussed in the Considerations
Manual and are applicable, at least in part, to most land-application systems.
Special consideration must be given to standards relating to the groundwater.
A.3. DESCRIPTION, OPERATION AND CONTROL OF WASTEWATER
TREATMENT FACILITIES
This chapter will be the heart of the operation and maintenance manual in
which each component of the land-application system is described, and the
operation and control procedures are detailed. The chapter should be sub-
divided by components, with the following subdivisions suggested for land-
application systems in place of those suggested on page 56 of the Considerations
Manual:
Preapplication treatment facilities
Transmission system
Storage facilities
Application of effluent
Soils and plants
Recovery systems
The major system components should be subdivided into units to allow a
thorough description and to aid in understanding the interactions of the
various units.
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Information that should be presented for each individual component includes:
Description of component and major subcomponents
Relationship to adjacent components
Methods of control
Startup
Normal operation
Common operating problems
Alternate operation
Emergency operations and failsafe procedures
Monitoring and laboratory controls
The preceding list has been slightly modified from the one suggested in the
Considerations Manual; however, the discussion and examples contained there-
in are generally applicable for land-application systems. It is expected that
further modification will be necessary or desirable for various components of
many systems.
Additional considerations pertinent to the content of this chapter are discussed
in Sections B, C, and D.
A.4. DESCRIPTION, OPERATION AND CONTROL OF SLUDGE-
HANDLING FACILITIES
Sludge-handling facilities should be described and operating and control proce-
dures should be outlined in this chapter. The extent and significance of the
chapter will be highly variable and will depend upon the method and degree of
preapplication treatment to be employed. In many cases, the entire chapter
may be unnecessary if sludge-handling facilities are not complex and are
included in the previous chapter (ffl-A.3.).
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A. 5. PERSONNEL
Personnel requirements should be discussed with respect to:
Manpower requirements/staff
Qualifications
Certification
Consideration must be given to special skills and qualifications necessary for
land-application systems, such as those relating to agricultural practices and
groundwater monitoring. In all other respects, the discussion in the Consid-
erations Manual is generally applicable to land-application systems.
A. 6. LABORATORY TESTING
The material to be presented on the laboratory testing program should
generally include:
* The purpose of the sampling program
The sampling schedule
The list of operation/laboratory references
Interpretation of laboratory tests
Sample laboratory worksheets
The suggested format and discussion of the laboratory testing program con-
tained in the Considerations Manual are applicable in most respects to most
land-application systems; however, a wider range of tests, such as those to
determine the uptake of certain constituents by crops, and various soils tests
are often necessary. Additional specific considerations for land-application
systems are discussed later in Section C.
A. 7-A. 13. REMAINING MANUAL CHAPTERS
The remaining chapters to be included in the operation and maintenance manual
will normally deal with:
A.7. Records
A. 8. Maintenance
A. 9. Emergency Operating and Response Program
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A. 10. Safety
A. 11. Utilities
A. 12. Electrical System
A. 13. Appendixes
Each is discussed in detail in the Considerations Manual, and is generally
applicable to all wastewater treatment systems, including those employing
land application. Modification of the suggested format may be necessary or
desirable in many cases so that the manual may be tailored to fit each
system.
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Section B
OPERATING PROCEDURES
A number of special topics concerning operating procedures for land-appli-
cation systems are discussed in this section, including:
Application of effluent
Agricultural practices
Recovery of renovated water
Storage
Special problems and emergency conditions
Operating procedures for system components that are generally common to
conventional systems, such as those for preapplication treatment facilities,
are not discussed.
B. 1. APPLICATION OF EFFLUENT
The procedures for the application of effluent to the land must be clearly
defined because many distribution systems will be unique and the operators
must be able to vary the application in response to environmental changes.
Descriptions of the application system and the operating procedure should be
included in Chapter 3 of the operation and maintenance manual. Considera-
tions relating to both the distribution system and the schedule of application
are discussed in the following paragraphs.
B.I.a. Distribution System
The distribution system should be described and the operating and control
procedures outlined in a manner similar to the other components, as described
previously in Subsection m-A.3. For most systems, including those for
overland flow and infiltration-percolation facilities, operating procedures
will be based primarily on standard irrigation practices. Standard references
on irrigation [115, 155, 184] should be consulted along with manufacturer's
operating instructions. Valve sequences, operating pressures, startup and
shutdown procedures should be detailed. Solution of typical problems that
may be encountered with the distribution of wastewater, such as the clogging
of nozzles with suspended solids, should be included.
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B. 1 . b Schedule of Application
Because this portion of the manual will be referred to frequently, it is
imperative that application schedule details be presented clearly. Effluent
application schedules should be presented in terms of the rates , periods of
application and resting, and seasonal variations as developed in the design
(II-C.6.). Also included should be the sequence of rotation of plots or basins,
seasonal variations in rotation, and descriptions of conditions that may require
temporary cessation of application. The range of acceptable application rates
and ratios of resting to wetting should be included as a guide to assist oper-
ators in making necessary operational changes.
B. 2. AGRICULTURAL PRACTICES
Operating procedures relating to agriculture will play a major role in the
operation of irrigation systems, and a lesser but still significant role for
overland flow and infiltration-percolation systems. Procedures regarding
agricultural practices should normally be described under "soils and plants"
in Chapter 3 of the manual (III-A.3.). Factors relating to agriculture that
are discussed in this section include:
« Purpose of the crop
Description of crop requirements
Planting, cultivation, and harvesting
B. 2. a. Purpose of the Crop
The purpose for which vegetation is to be grown should be stated clearly in
the manual so that the system may be operated to best achieve that goal. The
primary consideration of importance to the operator is whether optimization
of crop yields or maximization of renovation and effluent application is to be
emphasized. Other desired results, such as increased infiltration rates,
and combinations of desired results should also be described.
B. 2. b. Description of Crop Requirements
Crop requirements should be specified with respect to:
Water requirements and tolerance
Nutrient requirements
Necessary soil amendments
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Climatic conditions
Public health requirements
Methods for evaluating crop performance with respect to these requirements
and operating procedures to ensure that the requirements are met should be
described.
B. 2.c. Planting, Harvesting, and Cultivation
Procedures should be described for all aspects of crop management, including:
planting, harvesting, and cultivation. A general schedule for crop manage-
ment should be included, and methods of determining optimum dates for
planting, harvesting, and cultivation should be explained. Related events and
requirements, such as the requirement for ceasing application a certain
number of days prior to harvesting, should also be described.
B.3. RECOVERY OF RENOVATED WATER
Operating procedures for the recovery of renovated water should be described
for all systems which employ: (1) pumped withdrawal, (2) tile drainage, or
(3) collection of runoff from overland flow. Detailed considerations for the
operation and maintenance of recovery systems are presented in various
references, most notably in Drainage of Agricultural Land [38] . Standard
procedures, operating parameters, and methods of control should be listed
for both normal flow conditions and peak flows. Quality monitoring and dis-
charge requirements should also be listed. Any point source municipal dis-
charge requires a permit under the NPDES program. Systems built with EPA
construction grant funds are controlled by conditions of the construction grant.
Special procedures for unusual or emergency conditions, such as the collection
and storage of contaminated storm runoff for later application, should be
described.
B.4. STORAGE
Storage of effluent to be applied will often present special problems for land-
application systems, in that large volumes of water must frequency be stored
for long periods of time. For this reason, procedures for the operation of
the effluent storage facilities should be described in detail. If the potential
for special problems, such as odors resulting from anaerobic conditions
or the growth of unwanted aquatic life exists, special procedures and methods
of control should be included.
B.5. SPECIAL PROBLEMS AND EMERGENCY CONDITIONS
Operating procedures for special problems and emergency conditions should
be described in Chapter 9 of the manual. Design features with respect to
flexibility (II-C.8.) and reliability (II-C.9.) will form the basis for any
special operating procedures that may be required.
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Section C
MONITORING
The monitoring requirements of a land-application system must receive
special consideration, because of the wide variety and complexity of para-
meters and effects that should be analyzed. Requirements should be
described with respect to each system component in Chapter 3 of the
Operations and Maintenance Manual and with respect to laboratory testing in
Chapter 6. If the monitoring requirements are complex, it may be appropriate
to devote an entire chapter to the monitoring program or to expand Chapter 6
(Laboratory Testing) to include a description of the entire program.
In the following subsections, monitoring considerations that should be included
in the operation and maintenance manual are discussed with respect to:
Parameters to be monitored
Monitoring procedures
Interpretation of results
C.I. PARAMETERS TO BE MONITORED
As in most conventional treatment facilities, concentrations of certain constitu-
ents should be monitored at various stages in the treatment process. Gener-
ally, for land-application systems, water quality should be analyzed at the
following stages:
Influent into the system
Following preapplication treatment
Following storage
Groundwater
Recovered water (from pumped withdrawal, underdrains,
or collected runoff from overland flow)
Water-quality parameters that must be analyzed at each of these stages, will
vary. Monitoring at the first three stages will be primarily for system control
and optimization purposes. Consequently, the parameters to be analyzed will
be those identified as indexes of previous treatment efficiency, and those that
may indicate the requirement for operational adjustments during subsequent
treatment processes.
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Water quality parameters that should be analyzed in the groundwater are those:
(1) given in the proposed Criteria for Water Quality [29], or any revisions
thereof, (2) required by state or local agencies, (3) given in the report on
Alternative Waste Treatment Management Techniques for Best Practicable
Waste Treatment [31 and any revisions thereof, and (4) necessary for system
control. Monitoring requirements for recovered water will depend upon the
disposition of that water. If the water is to be discharged, the parameters
to be analyzed must include those required in the NPDES permit. If the water
is to be reused, analysis of additional parameters may be required by cogni-
zant public health agencies.
In addition, a variety of other system effects, in some cases, should also be
monitored both at the site and in the surrounding area. These include:
Groundwater levels and direction of flow (I-C. 2. e.)
Physical and chemical soil characteristics (I-C. 2. c. 1)
Growth and production characteristics of crops or vegetation
Various environmental effects (on adjacent land, animal and insect
lives, etc.)
C. 2. MONITORING PROCEDURE
Detailed procedures for monitoring must be described for each aspect of the
monitoring program, including the location of sampling points, and the fre-
quency of sampling. Descriptions of the appropriate laboratory tests, where
the test is to be performed, and by whom, should be included in Chapter 6 for
each parameter that is to be monitored. The type of scope of information
that is being sought should be described. Blakeslee [14] presents some sug-
gested procedures for groundwater monitoring.
C. 3. INTERPRETATION OF RESULTS
Charts, graphs, ranges of satisfactory values, and upper limits requiring
remedial action must.be included for each major parameter where applicable.
A range of results that are to be expected during normal operation should be
indicated, along with those results that may be an indication of a malfunction
in the system.' Whenever possible, indications of malfunctions should be re-
lated to appropriate measures of control and corrective procedures (III-D.3).
During the initial years of operation, monitoring results should be analyzed
and reviewed with the designer or various specialists. For example, inter-
pretation of groundwater data by a geohydrologist may be necessary ' Results
that should be referred to personnel outside the normal operating staff should
be identified.
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C. 4. SURVEILLANCE AND REPORTING
Those results which relate directly to NPDES permits or other requirements
should be specifically noted, as should results which come under the surveil-
lance of various agencies such as state or local water resource boards or
public health agencies.
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Section D
IMPACT CONTROL
An important consideration in the review of the operation and maintenance
manual is whether the control of potential adverse effects has been adequately
addressed. Each potential adverse effect that was identified in the facilities
plan and environmental assessment (I-F.) should be considered. Aspects
of impact control that should be included are:
Description of possible adverse effects
Indexes of critical effects
Methods of control
Methods of remedial action
D. 1. DESCRIPTION OF POSSIBLE ADVERSE EFFECTS
All possible adverse effects of the system, including environmental, public
health, social, and economic effects that were previously identified in either
the planning or design stage should be identified and described. The intro-
ductory section of Chapter 3 of the manual is suggested as a reasonable place
to present this information. In addition, possible adverse effects that may
result from any one particular component of the system should be discussed
in Chapter 9.
D. 2. INDEXES OF CRITICAL EFFECTS
Critical effects of a treatment system are those adverse impacts that must be
controlled. Whenever possible, these indexes or first indications of critical
effects should be described. They should be related to:
Results of monitoring program
Unusual or emergency conditions at the site
Malfunction of various system components
General observations of the operator
Provisions should be made so that the overall effects of the system based on
all available information can be routinely monitored.
131
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D. 3. METHODS OF CONTROL
Methods of control should be described with respect to both normal operating
controls and procedures, and adjustments or modifications to those procedures
for each possible adverse effect. For example, elimination of standing water
on the application area will normally be a standard procedure for most sys-
tems; however, it is also a method of control for mosquito breeding. Gener-
ally, each method of control should be described by component in Chapter 3
of the manual (m-A. 3.) and should be specifically related to the effect it
controls (IH-D. 1.), and to the indication of that effect (ffl-D. 2.).
A convenient way of relating indications of critical effects to the appropriate
methods of control is through the inclusion of a section on troubleshooting.
Provisions should be included for the periodic reevaluation of control methods,
particularly for the control of long-range effects. It should, however, be
emphasized that land application is a dynamic process and that monitoring
results will often be variable. Consequently, control measures that take
trends into account should be employed.
D.4. METHODS OF REMEDIAL ACTION
Remedial actions should be described for the various adverse effects that may
result from system or component failure, accidents, and other unusual or
emergency conditions. The objectives of these actions should be to prevent
or minimize the adverse effects when emergency conditions are encountered,
or to correct the situation once damage has been done. Depending on the
system, necessary remedial actions may generally be described in Chapter 9
of the manual, Emergency Operating and Response Program (DI-A).
132
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APPENDIXES
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Appendix A
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142. Sepp, E. Survey of Sewage Disposal by Hillside Sprays. Bureau of
Sanitary Engineering. California State Department of Public Health,
Berkeley. March 1965.
144
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143. Sepp, E. The Use of £ewage for Irrigation A Literature Review.
Bureau of Sanitary Engineering. California State Department of Public
Health, Berkeley. 197.L.
144. Skulte, B. P. Agricultural Values of Sewage. Sewage & Industrial
Wastes, 25, No. 11, pp 1297-1303. 1953.
145. Skulte, B. P. Irrigation with Sewage Efflueits. Sewage & Industrial
Wastes, 28, No. 1, pp 'J6-43. 1956.
146. Smith, R. Cost of Conventional and Advanced Treatment of Wastewater.
Journal WPCF, 40, No. 9, pp 1546-1574. 1968.
147. Soil-Plant-Water Relationships. Irrigation, Chapter 1. SCS National
Engineering Handbook, Section 15. Soil Conservation Service, U.S.
Department of Agriculture. March 1964.
148. Sopper, W. E. Crop Selection and Management Alternatives-Perennials.
Proceedings of the Joint Conference on Recycling Municipal Sludges and
Effluents on Land, Champaign, University of Illinois. July 1973. pp 143-154.
149. Sopper, W. E. and L. T. Kardos, (ed.). Recycling Treated Municipal
Wastewater and Sludge through Forest and Cropland. University Park,
The Pennsylvania State University Press. 1973.
150. Sopper, W. E. and L. T. Kardos. Vegetation Responses to Irrigation
with Treated Municipal Wastewater. In: Recycling Treated Municipal
Wastewater and Sludge through Forest and Cropland, Sopper, W. E. and
L. T. Kardos, (ed.). University Park, The Pennsylvania State
University Press. 1973. pp 271-294.
151. Sopper, W. E. and J. Sagmuller. Forest Vegetation Growth Responses
to Irrigation with Municipal Sewage Effluent. Reprint Series No. 23.
Institute for Research on Land and Water Resource. University Park,
The Pennsylvania State University. March 1971.
152. Sorber, C. A. Problem Definition Study: Evaluation of Health and
Hygiene Aspects of Land Disposal of Wastewater at Military Installations.
U.S. Army Medical Environmental Engineering Research Unit.
USAMEERU Report No. 73-02. Edgewood Arsenal, Maryland. August
1972.
153. Sorber, C. A. Protection of Public Health. Proceedings of the Confer-
ence on Land Disposal of Municipal Effluents and Sludges. New Brunswick,
Rutgers University. March 12-13, 1973. pp 201-209.
154. Spray Irrigation Manual. Publication No. 31. Bureau of Water Quality
Management. Pennsylvania Department of Environmental Resources.
Harrisburg, Pennsylvania. 1972.
145
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155. Sprinkler Irrigation. Irrigation, Chapter 11. SCS National Engineering
Handbook, Section 15. Soil Conservation Service. U.S. Department of
Agriculture. July 1968.
156. Stevens, R. M. Green Land Clean Streams: The Beneficial Use of
Waste Water through Land Treatment. Center for the Study of
Federalism. Philadelphia, Temple University. 1972.
157. Studies in Water Reclamation. Sanitary Engineering Research Laboratory.
Technical Bulletin No. 13. Berkeley, University of California.
July 1955.
158. Sullivan, D. Wastewater for Golf Course Irrigation. Water & Sewage
Works, 117, No. 5, pp 153-159. 1970.
159. Sullivan, R. H. Federal and State Legislative History and Provisions
for Land Treatment of Municipal Wastewater Effluents and Sludges.
Proceedings of the Joint Conference on Recycling Municipal Sludges and
Effluents on Land, Champaign, University of Illinois. July 1973. pp 1-8.
160. Sullivan, R. H., et al. Survey of Facilities using Land Application of
Wastewater. Office of Water Program Operations. Environmental
Protection Agency. July 1973.
161. Tchobanoglous, G. Physical and Chemical Processes for Nitrogen
Removal Theory and Application. Proceedings of the 12th Sanitary
Engineering Conference. Urbana, University of Illinois. 1970.
162. Tchobanoglous, G. Wastewater Treatment for Small Communities.
Presented at the Conference on Rural Environmental Engineering.
Warren, Vermont. September 26-28, 1973.
163. Thomas, R. E. Fate of Materials Applied. Conference on Land Disposal
of Wastewaters. Michigan State University. December 1972.
164. Thomas, R. E. Spray-Runoff to Treat Raw Domestic Wastewater.
International Conference on Land for Waste Management. Ottawa,
Canada. October 1973.
165. Thomas, R. E. and T. W. Bendixen. Degradation of Wastewater
Organics in Soil. Journal WPCF, 41, No. 5, Part 1, pp 808-813. 1969.
166. Thomas, R. E. and C. C. Harlin, Jr. Experiences with Land Spreading
of Municipal Effluents. Presented at the First Annual IFAS Workshop
on Land Renovation of Waste Water in Florida, Tampa. June 1972.
146
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167. Thomas, R. E. and J. P. Law, Jr. Soil Response to Sewage Effluent
Irrigation. Proceedings of the Symposium on Municipal Sewage Effluent
for Irrigation. Louisiana Polytechnic Institution. July 30, 1968.
168o Thomas, R. E., W. A. Schwartz, and T. W. Bendixen. Soil Chemical
Changes and Infiltration Rate Reduction Under Sewage Spreading. Soil
Science Society of America, Proceedings, 30, pp 641-646. 1966.
169. Thornthwaite, C. W. An Approach Toward a Rational Classification of
Climates. Geographical Review, 38, No. 1, pp 55-94. 1948.
170. Thornthwaite, C. W. and J. R. Mather. The Water Balance. Publica-
tions in Climatology, 8, No. 1. Laboratory of Climatology. 1955.
171. Urie, D. H. Phosphorus and Nitrate Levels in Groundwater as Related
to Irrigation of Jack Pine with Sewage Effluent. In: Recycling Treated
Municipal Wastewater and Sludge through Forest and Cropland.
Sopper, W. E. and L. T. Kardos, (ed.). University Park, The
Pennsylvania State University Press. 1973. pp 176-183.
172. van der Goot, H. A. Water Reclamation Experiments at Hyperion.
Sewage & Industrial Wastes, 29, No. 10, pp 1139-1144. 1957.
173. Van Note, R. H., P. V. Hebert, and R. M. Patel. A Guide to the
Selection of Cost-Effective Wastewater Treatment Systems. Municipal
Wastewater Systems Division, Engineering and Design Branch. Environ-
mental Protection Agency. 1974.
174. Waste into Wealth. Melbourne and Metropolitan Board of Works.
Melbourne, Australia. 1971.
175. Waste Water Reclamation. California State Department of Public Health,
Bureau of Sanitary Engineering. California State Water Quality Control
Board. November 1967.
176. Water Quality Criteria. National Technical Advisory Committee.
FWPCA. Washington, D. C. 1968.
177. Wells, D. M. Groundwater Recharge with Treated Municipal Effluent.
Proceedings of the Symposium on Municipal Sewage Effluent for Irrigation.
Louisiana Polytechnic Institution. July 30, 1968.
178. Wentink, G. R. and J. E. Etzel. Removal of Metal Ions by Soil. Journal
WPCF, 44, No. 8, pp 1561-1574. 1972.
179. Wesner, G. M. and D. C. Baier. Injection of Reclaimed Wastewater into
Confined Aquifers. Journal AWWA, 62, No. 3, pp 203-210. 1970.
147
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180. Whetstone, G. A., H. W. Parker, and D. M. Wells. Study of Current and
Proposed Practices in Animal Waste Management. Office of Air and Water
Programs, Environmental Protection Agency. January 1974.
181. Williams, T. C. Utilization of Spray Irrigation for Wastewater Disposal in
Small Residential Developments. In: Recycling Treated Municipal Waste-
water and Sludge through Forest and Cropland, Sopper, W. E. and
L. T. Kardos, (ed.). University Park, The Pennsylvania State University
Press. 1973. pp 385-395.
182. Winneberger, J. T. and J. W. Klock. Current and Recommended Prac-
tices for Subsurface Waste Water Disposal Systems in Arizona. Engineer-
ing Research Center, Arizona State University. July 1973.
183. Woodley, R. A. Spray Irrigation of Organic Chemical Wastes. Proceed-
ings of the 23rd Industrial Waste Conference. Lafayette, Purdue Univer-
sity. 1968. pp 251-261.
184. Younger, V. B. Ecological and Physiological Implications of Greenbelt
Irrigation with Reclaimed Water. In: Recycling Treated Municipal
Wastewater and Sludge through Forest and Cropland, Sopper, W. E. and
L. T. Kardos, (ed.). University Park, The Pennsylvania State Univer-
sity Press. 1973. pp 396-407.
185. Zimmerman, J. P. Irrigation. New York, John Wiley & Sons, Inc.
1966.
148
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Appendix B
SELECTED ANNOTATED BIBLIOGRAPHY
In this appendix, 17 references that may be of value to the reviewer are listed
and briefly described. The first three references provide an assessment of the
state-of-the-art of land application and the fourth is an extensive annotated bibli-
ography. Following the existing guidelines for operation and maintenance
manuals are a group of three proceedings from recent conferences, each with a
number of papers by various authors, in which a wide range of different topics
are addressed. The remaining references include technical handbooks and indi-
vidual papers which address a number of specific topics.
1. Pound, C. E. and R. W. Crites. Wastewater Treatment and Reuse by Land
Application, Volumes I and II. Office of Research and Development,
Environmental Protection Agency. August 1973.
In the summary report (Volume I), the results of a nationwide study conducted on
the current knowledge and techniques of land application are given. Factors in-
volved in system design and operation are discussed for irrigation, overland
flow, and infiltration-percolation methods. In addition, evaluations are made of
environmental effects, public health considerations, and costs.
In Volume II, detailed examinations are made of the literature and the selected
sites visited. The relationship between climate and land application is examined.
The state-of-the-art of land application of industrial wastewater is also reported.
In addition, sections on cost evaluation, and land-application potential, and his-
tories of several cases of irrigation abandonment are included.
2. Sullivan, R. H., et al. Survey of Facilities using Land Application of Waste-
water. Office of Water Program Operations, Environmental Protection
Agency. July 1973.
The results of a field survey of 63 municipal and 19 industrial systems in 1972
using irrigation with wastewater are presented in this report. The data col-
lected are analyzed statistically using five climatic zones for the U. S. Abstracts
from foreign experience and a state-by-state summary of health regulations are
included. The appendix material is quite valuable since it includes all the raw
data from the visits plus narratives and results of a parallel mail survey of 78
municipalities and 36 industries. Also appended are two excellent papers by
Richard E. Thomas, soil scientist with the EPA.
149
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3. Reed, S. C. Wastewater Management by Disposal on the Land. Special
Report 171. Cold Regions Research and Engineering Laboratory.
U.S. Army Corps of Engineers. May 1972.
This state-of-the-art review considers three land disposal techniques: spray
irrigation, overland runoff, and rapid infiltration. Each technique is considered
in detail, including such aspects as wastewater characteristics, water-quality
goals, site conditions, operational criteria, and ecosystem response. The con-
cept of renovative capacity is introduced in which the assumption is that there is
a finite depth of soil in which major renovation occurs. The report was pre-
pared by a multidisciplined team including hydrologists, geologists, climatol-
ogists, soil scientists, and sanitary engineers. The emphasis is on environ-
mental responses to land application, but design components are discussed.
4. Land Application of Sewage Effluents and Sludges: Selected Abstracts.
Office of Research and Development, Environmental Protection Agency.
1974.
This document is a combined annotated bibliography of a wide range of subject-
matter related to application of sewage effluents and sludges to the land. Using
the EPA document, Agricultural Utilization of Sewage Effluent and Sludge (pre-
pared by Dr. Law) as a basis, inputs were received from (1) the state-of-the-
art study by Pound and Crites [125], (2) the literature survey by Sullivan [160],
(3) the Joint Conference at the University of Illinois (see No. 8), and (4) the
state-of-the-art assessment of sludge spreading conducted by Battelle Columbus.
These selected abstracts have been indexed by author, title, and location (for
case studies). A strict division has been made between abstracts dealing with
effluents and those dealing with sludges.
5. Green, R. L., G. L. Page, Jr., and W. M. Johnson. Considerations for
Preparation of Operation and Maintenance Manuals. Office of Water Pro-
gram Operations, Environmental Protection Agency.
In these guidelines, general considerations for the preparation of operation and
maintenance manuals are presented, and a format for the manual is suggested.
Each of the twelve chapters from the suggested format is then described in
detail with respect to content, scope, and useful references. Checklists are
included for evaluating the operation and maintenance manuals for both munici-
pal wastewater treatment facilities, and for pumping station and/or pipelines.
In addition, guidelines for estimating manual preparation costs are included.
150
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6. Sopper, W. E. and L. T. Kardos, (ed.). Recycling Treated Municipal
Wastewater and Sludge through Forest and Cropland. University Park,
Pennsylvania. The Pennsylvania State University Press. 1973.
The proceedings of a symposium co-sponsored by the Pennyslvania State
University, the U.S. Department of Agriculture (Forest Service), and the
Environmental Protection Agency, and held in 1972 are presented in this book.
Thirty-two separate papers are included, with topics ranging from the funda-
mentals of soil treatment systems to research needs. Wastewater quality
changes during recycling, and responses of the soil, vegetation, and other ele-
ments of the ecosystem are discussed. Examples of several operating and pro-
posed systems are reported, and the status of guidelines for land disposal of
wastewater are discussed.
7. Proceedings of Conference on Land Disposal of Municipal Effluents and
Sludges. Rutgers University. March 1973.
Current research and studies on land application of municipal effluents and
sludges are reported in nineteen separate papers. Overviews of land treatment
are presented from the viewpoint of the Environmental Protection Agency, an
environmentalist, and a state regulatory director. Topics relating to the current
knowledge of wastewater characteristics, fate of materials applied, and public
health effects are addressed. Preliminary results of Environmental Protection
Agency research and state-of-the-art studies are also given.
8. Proceedings of the Joint Conference on Recycling Municipal Sludges and
Effluents on Land. Champaign, Illinois. July 1973.
This document includes information gathered at the Research Needs Workshop,
sponsored by the ad-hoc subcommittee of EPA-USDA-Universities representa-
tives. In addition to reports of the ten workshop sessions, twenty-four individual
papers on aspects of soil treatment ranging from inorganic reactions in the soil
to public acceptance of new systems are presented. Soil-plant relationships, and
crop and food chain effects are described. Some of the capabilities of the Soil
Conservation Service and the Agricultural Extension Service are outlined and
some informal opinions on the outlook of the Food and Drug Administration are
given.
9. Pair, C. H. (ed.). Sprinkler-Irrigation. 3rd Edition and Supplement.
Silver Spring. Sprinkler Irrigation Association. 1969 and 1973.
In this book, all aspects of spray irrigation design from pumping plants to distri-
bution systems are discussed. Besides crop irrigation, uses of sprinklers such
as for environmental control (frost and heat control), fertilizer, and chemical
applications, waste disposal, and fire protection are delineated. Soil-plant-
water relations are explained with all current techniques for management of
irrigation. Irrigation water requirements for many crops are included along
151
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with methods for determining water demands. The text is especially useful in
the hydraulic design of sprinkler systems.
The supplement, published in 1973, consists of an additional four chapters
including (1) turf irrigation, (2) continuously moving mechanical sprinkler sys-
tems, (3) land application of liquid wastes (good design advice), and (4) thermo-
plastic pipe.
10. Zimmerman, J. P. Irrigation. John Wiley & Sons, Inc. New York. 1966.
In this book, Zimmerman presents a comprehensive engineering approach to the
design of irrigation systems. All aspects of the system are discussed, and a
wide range of design elements is described for each of the irrigation methods
(corrugation and furrow, border strip, sprinkling, flush flood spreading, and
subirrigation). Other elements that are related to the system, such as reser-
voirs, canals, pumping, piping, and measuring devices, are also described.
11. Drainage of Agricultural Land. Soil Conservation Service, U. S. Depart-
ment of Agriculture. Water Information Center, Inc. 1973.
This handbook, which was reproduced from the SCS National Engineering Hand-
book, presents a complete discussion of drainage principles as well as detailed
descriptions of design features. Both surface and subsurface drainage are con-
sidered. In addition, sections on dikes, drainage pumping, drainage of organic
soils, and drainage of tidal lands are included.
12. Chapman, H. D., (ed.). Diagnostic Criteria for Plants and Soils. Abilene,
Quality Printing Company, Inc. 1965.
In this comprehensive reference, the effects of a large number of elements on
plants and soils are described. Methods for diagnosing the existing status (defi-
ciencies or toxic levels) and control provisions are described for each element.
The effects of alkali and saline soils, and organic soil toxins are also consid-
ered. In addition, an extensive table is included, which shows levels of various
elements (ranging from deficient to toxic levels) for a large number of plants.
13. Thomas, R. E. and C. C. Harlin, Jr. Experiences with Land Spreading of
Municipal Effluents. First Annual IF AS Workshop on Land Renovation of
Wastewater in Florida. Tampa, Florida. June 1972.
An overview of the use of land application as a treatment process is presented,
in which the three major methods (infiltration-percolation, cropland irrigation,
and spray-runoff) are defined. The general applicability and potential of each
method are discussed, and Environmental Protection Agency-sponsored research
projects are described.
152
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14. Thomas, R. E. Spray-Runoff to Treat Raw Domestic Wastewater.
International Conference on Land for Waste Management. Ottawa,
Canada. October 1973.
Field studies conducted by the Environmental Protection Agency at Ada,
Oklahoma, in which the capabilities of a spray-runoff (overland flow) system
were evaluated, are described. During the 18-month study period, com-
minuted raw wastewater was applied to three experimental plots at varying
loading rates. Results of the study are discussed, with removal efficiencies
being reported for: COD, BOD, TOC, nitrogen, phosphorus, and suspended
solids.
15. Bouwer, H., R. C. Rice, andE.D. Escarcega. Renovating Secondary
Sewage by Ground Water Recharge with Infiltration Basins. Office of
Research and Monitoring, Environmental Protection Agency. March 1972.
A five year infiltration-percolation demonstration project at Flushing Meadows,
Arizona, is detailed in this report. The feasibility of renovating activated sludge
effluent was studied using six parallel basins in loamy sand. The wide variety
of application schedules that were tried are described in the report, and results
of the groundwater analyses are given with respect to: suspended solids, BOD,
fecal coliform, nitrogen, phosphorus, fluorides, boron, and heavy metals.
Special emphasis is given to nitrogen removal.
16. Law, J. P. , R. E. Thomas, and L. H. Myers. Cannery Wastewater Treat-
ment by High-Rate Spray on Grassland. Journal WPCF, 42, No. 9,
pp 1621-1631. 1970.
A one-year study of an industrial spray-runoff (overland flow) system in Paris,
Texas, is described in this report. Four separate plots of varying slopes,
lengths, soil conditions, and periods of operation were studied. Summaries of
quality analyses are presented for the wastewater applied, system effluent, and
soil water. Removal efficiencies are presented with respect to: BOD, COD,
suspended solids, nitrogen, and phosphorus.
17. Kirby, C. F. Sewage Treatment Farms. Department of Civil Engineering.
University of Melbourne. 1971.
In this paper, the three methods of treating wastewater from the City of
Melbourne land filtration, grass filtration, and lagooning are discussed. The
land filtration process consists of pasture irrigation with grazing by cattle and
sheep. Grass filtration, known in the United States as overland flow, is notable
because it is the only known full-scale system using municipal wastewater. Also
of note is the fact that in this system wastewater is applied by flooding, as op-
posed to spraying, which is the only application method presently employed by
U. S. industries. Loadings and removals of various wastewater constituents are
included in the paper.
153
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Appendix C
GLOSSARY OF TERMS, ABBREVIATIONS, SYMBOLS,
AND CONVERSION FACTORS
TERMS
Adsorption A process in which soluble substances are attracted to and held at
the surface of soil particles.
Aerosol A suspension of fine solid or liquid particles in air or gas.
Alkali soil A soil with a high degree of alkalinity (pH of 8.5 or higher) or with
a high exchangeable sodium content (15 percent or more of the exchange capac-
ity), or both.
Application rate The rate at which a liquid is dosed to the land (in./hr, ft/yr,
etc.).
Aquifer A geologic formation or stratum that contains water and transmits it
from one point to another in quantities sufficient to permit economic development,
Border strip method Application of water over the surface of the soil. Water
is applied at the upper end of the long, relatively narrow strip.
Conductivity Quality or capability of transmitting and receiving. Normally
used with respect to electrical conductivity (EC).
Consumptive use Synonymous with evapotranspiration.
Contour check method Surface application by flooding. Dikes constructed at
contour intervals to hold the water.
Conventional wastewater treatment Reduction of pollutant concentrations in
wastewater by physical, chemical, or biological means.
Drain ability Ability of the soil system to accept and transmit water by infil-
tration and percolation.
Evapotranspiration The unit amount of water used on a given area in trans-
piration, building of plant tissue, and evaporation from adjacent soil, snow, or
intercepted precipitation in any specified time.
155
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Field area Total area of treatment for a land-application system including the
wetted area.
Fixation A combination of physical and chemical mechanisms in the soil that
act to retain wastewater constituents within the soil, including adsorption,
chemical precipitation, and ion exchange.
Flooding A method of surface application of water which includes border strip,
contour check, and spreading methods.
Grass filtration See overland flow.
Groundwater - The body of water that is retained in the saturated zone which
tends to move by hydraulic gradient to lower levels.
Groundwater table - The free surface elevation of the groundwater; this level
will rise and fall with additions or withdrawals.
Infiltration - The entrance of applied water into the soil through the soil-water
interface.
Infiltration-per eolation An approach to land application in which large volumes
of wastewater are applied to the land, infiltrate the surface, and percolate
through the soil pores.
Irrigation Application of water to the land to meet the growth needs of plants.
Land application The discharge of wastewater onto the soil for treatment or
reuse.
Lithology The study of rocks; primarily mineral composition.
Loading rate The average amount of liquid or solids applied to the land over a
fixed time period, taking into account periodic resting.
Lysimeter A device for measuring percolation and leaching losses from a
column of soil. Also a device for collecting soil water in the field.
Micronutrient A chemical element necessary in only small amounts (less than
1 mg/1) for microorganism and plant growth.
Mineralization - The conversion of an element from an organic form to an
inorganic form as a result of microbial decomposition.
Overland flow Wastewater treatment by spray-runoff (also known as "grass
filtration" and "spray runoff") in which wastewater is sprayed onto gently slop-
ing, relatively impermeable soil that has been planted to vegetation. Biological
oxidation occurs as the wastewater flows over the ground and contacts the biota
in the vegetative litter.
156
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Pathogenic organisms Microorganisms that can transmit diseases.
Percolation The movement of water beneath the ground surface both vertically
and horizontally, but above the groundwater table.
Permeability - The ability of a substance (soil) to allow appreciable movement
of water through it when saturated and actuated by a hydrostatic pressure.
Phytotoxic Toxic to plants.
Primary effluent Wastewater that has been treated by screening and
sedimentation.
Ridge and furrow method The surface application of water to the land through
formed furrows; wastewater flows down the furrows and plants may be grown
on the ridges.
Saline soil A nonalkali soil containing sufficient soluble salts to impair its
productivity.
Secondary treatment Treatment of wastewater which meets the standards set
forth in 40 CFR 133.
Sewage farming Originally involved the transporting of sewage to rural areas
for land disposal. Later practice included reusing the water for irrigation and
fertilization of crops.
Soil texture The relative proportions of the various soil separates sand,
silt, and clay.
Soil water - That water present in the soil pores in an unsaturated zone above
the groundwater table.
Spraying - Application of water to the land by means of stationary or moving
sprinklers.
Spray-runoff See overland flow.
Tilth - The physical condition of a soil as related to its ease of cultivation.
Transpiration - The net quantity of water absorbed through plant roots that is
used directly in building plant tissue, or given off to the atmosphere.
Viruses Submicroscopic biological structures containing all the information
necessary for their own reproduction.
Wetted area - Area within the spray diameter of the sprinklers.
157
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ABBREVIATIONS
acre-ft acre-foot
BOD biochemical oxygen demand
BPT - best practicable treatment technology
cm centimeter
COD chemical oxygen demand
cu. m cubic meter
deg C degree Centigrade
deg F degree Fahrenheit
EC electrical conductivity
ECdw - maximum EC of drainage water permissible for plant growth
ECe EC of saturation extract (from soil)
ECw EC of irrigation water
ENRCC Engineering News-Record construction cost (index)
FDA - Food and Drug Administration
fps feet per second
ft - foot
gal. gallon
gpm gallons per minute
ha hectare
hr hour
in. inch
kg kilogram
1 - liter
158
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Ib pound
m meter
max maximum
mgd million gallons per day
mg/1 milligrams per liter
min minute
ml milliliter
mm millimeter
mmho/cm millimhos per centimeter
MPN most probable number
ppm parts per million
psi pounds per square inch
SAR sodium adsorption ratio
SCS Soil Conservation Service
sec second
sq ft square foot
SS suspended solids
STPCC sewage treatment plant construction cost (index)
TOC total organic carbon
TDS -total dissolved solids
USDA U. S. Department of Agriculture
USGS - U. S. Geological Survey
wk week
yr year
159
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SYMBOLS
B boron
Ca calcium
Cu copper
K potassium
Fe iron
Mg magnesium
Mn manganese
N nitrogen
Na sodium
NH ammonia
o
NO nitrate
o
P phosphorus
S sulfur
Zn zinc
> greater than
< less than
M micro
CONVERSION FACTORS
million gallons x 3.06 = acre-feet
acre-inch x 27,154 = gallons
mg/1 x ft/yr x 2. 7 = Ib/acre/yr
mgd x 43.814 = 1/s
million gallons x 3785 = cu. m
160
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acre x 0.4047 = ha
acre-feet x 1234 - cu. m
Ib/acre x 1.121 = kg/ha
inch x 2. 540 = cm
ft x 30.48 = cm
161
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Appendix D
TYPICAL SUMMARY OF DESIGN CRITERIA FOR
LAND-APPLICATION SYSTEMS
Table D-l. IRRIGATION
Unita
Item
Flow
Design flow, avg annual
Design peak flow
Field area
Water balance
Design total annual precipitation
Relurn period
Design evapotranspiration
Design .percolation rate
Effluent application rate0
Nitrogen (as N) loading rate0
Other constituent loading rate0
Effluent water quality
TDS
Sodium adsorption ratio
Application rates
Length of operating season
Hourly rate (spray application)
Application period
Application cycle
Avg weekly rate
Max weekly rate6
Storage capacity
Rate of recovery of renovated water
English
mgd
mgd
acres
in. /yr
yr
in. /yr
in. /yr
in. /yr
Ib/acre/yr
Ib/acre/yr
mg/1
SAR
wk/yr
in. /hr
hr
day
in. /wk
in. /wk
mg
mgd
Metric Value
1/s
1/s
pm/yj-
y
pm/yr
pm/yr
kg/ha/yr r
kg/ha /yr
mp/1
SAR
p.m/hr
hr
day
pm/wk
1/s
a. Typical units are given with a choice between English and Metric systems.
b. When design values of different return periods are used for determining liquid loading rates and
storage capacities, both values should be shown.
c. If critical, indicate with an asterisk.
d. Combination of one application period and one drying period.
e. Includes additional flow from storage withdrawal.
163
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Table D-2. INFILTRATION-PERCOLATION
Unit"
Item
Flow
Design flow, avg annual
Design peak flow
Field area
Water balance
Design total annual precipitation
Return period
Design evapotranspiration
Design percolation rate
Effluent application rate0
Design runoff rate
Organic (BOD) loading ratec
Nitrogen (as N) loading rate0
- n
Phosphorus loading rate
Other constituent loading ratec
Application rates
Length of operating season
Avg weekly rate
Max weekly rate
Application period
Resting period
Storage
Rate or recovery of renovated water
English
mgd
mgd
acres
in. /yr
yr
in. /yr
in. /yr
in. /yr
in. /yr
Ib/acre/yr
Ib/acre/yr
Ib/acre/yr
Ib/acre/yr
wk/yr
in. /wk
in. /wk
hr
hr
mg
mgd
Metric Value
I/s
l/«
hfiptpres
Om/yr
yr
cm /vr
-------
Table D-3. OVERLAND FLOW
Unita
Item
Flow
Design flow, avg annual
Design peak flow
Field area
No. of basins or plots
Total area
Water balance
Design total annual precipitation
Return period
Design evapotranspiration
Design percolation rate
Effluent application rate0
Organic (BOD) loading rate0
Nitrogen (as N) loading rate0
ft
Phosphorus loading rate
Other constituent loading rate
Application rates
Length of operating season
Application period
Rated
Drying or resting period
Storage capacity
Rate of recovery of renovated water
English
mgd
mgd
acres
in. /yr
yr
in. /yr
ft/yr
ft/yr
Ib/acre/yr
Ib/acre/yr
Ib/acre/yr
Ib/acre/yr
wk/yr
day
in. /day
day
mg
mgd
Metric Value
1/s
1/s
Tnf.t4.arKR
nm/yr
yr
nm/yr
m/yr
m/yr
kg/ha/yr
kg/ha/yr
kg/ha/yr
kg/ha/yr
wlr/yr
Hay
p.m/Hay
rtav
r>n m
1/s
a. Typical units are given with a choice between English and Metric systems.
b. When design values of different return periods are used for determining liquid loading rates and
storage capacities, both values should be shown.
c. Indicate critical loading rate by means of asterisk.
d. Include ranges of periods and rates if significant seasonal variations exist.
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Appendix E
PROPOSED CALIFORNIA REGULATIONS
The following is a set of regulations that has been proposed to replace existing
California regulations. It is offered only as an example.
STATEWIDE RECLAMATION CRITERIA FOR USE OF RECLAIMED WATER FOR
IRRIGATION AND RECREATIONAL IMPOUNDMENTS
California Administrative Code, Title 17, Chapter 5, Subchapter 1, Group 12
Article 1. Definitions
8025. Definitions, (a) Reclaimed Water. Reclaimed water means water
which, as a result of treatment of waste, is suitable for a direct beneficial use
or a controlled use that would not otherwise occur.
(b) Reclamation Plant. Reclamation plant means an arrangement of de-
vices, structures, equipment, processes and controls which produce a reclaimed
water suitable for the intended reuse.
(c) Regulatory Agency. Regulatory agency means the California Regional
Water Quality Control Board in whose jurisdication the reclamation plant is
located.
(d) Direct Beneficial Use. Direct beneficial use means the use of re-
claimed water which has been transported from the point of production to the
point of use without an intervening discharge to waters of the State.
(e) Food Crops. Food crops mean any crops intended for human
consumption.
(f) Spray Irrigation. Spray irrigation means application of reclaimed
water to crops by spraying it from orifices in piping.
(g) Surface Irrigation. Surface irrigation means application of reclaimed
water by means other than spraying such that contact between the edible portion
of any food crop and reclaimed water is prevented.
(h) Restricted Recreational Impoundment. A restricted recreational im-
poundment is a body of reclaimed water in which recreation is limited to fishing,
boating, and other non-body-contact water recreation activities.
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(i) Non-Restricted Recreational Impoundment. A non-restricted
recreational impoundment is an impoundment of reclaimed water in which no
limitations are imposed on body-contact water sport activities.
(j) Landscape Impoundment. A landscape impoundment is a body of re-
claimed water which is used for aesthetic enjoyment or which otherwise serves
a function intended to exclude public contact.
(k) Approved Laboratory Methods. Approved laboratory methods are
those specified in the latest edition of "Standard Methods for the Examination of
Water and Wastewater, " prepared and .published jointly by the American Public
Health Association, the .American Water Works Association, and the Water Pol-
lution Control Federation, and which are conducted in laboratories approved by
the State Department of Health.
(1) Unit Process. Unit process means an individual stage in the waste-
water treatment sequence which performs a major single operation.
(m) Primary Effluent. Primary effluent is the effluent from a sewage
treatment process which provides partial removal of sewage solids by physical
methods so that it contains not more than 0.5 milliliter per liter per hour of
settleable solids as determined by an approved laboratory method.
(n) Oxidized Wastewater. Oxidized wastewater means wastewater in which
the organic matter has been stabilized, is nonputrescible, and contains dissolved
oxygen.
(o) Biological Treatment. Biological treatment means methods of waste-
water treatment in which bacterial or biochemical action is intensified as a
means of producing an oxidized wastewater as defined in (n).
(p) Secondary Sedimentation. Secondary sedimentation means the removal
by gravity of settleable solids remaining in the effluent after the biological treat-
ment process.
(q) Coagulated Wastewater. Coagulated wastewater means oxidized waste-
water in. which colloidal and finely divided suspended matter has been destabilized
and agglomerated by the addition of suitable floe-forming chemicals or by an
equally effective method.
(r) Filtered Wastewater. Filtered wastewater means an oxidized coagu-
lated wastewater which has been passed through natural undisturbed soils or
filter media, such as sand or diatomaceous earth, so that the turbidity as deter-
mined by an approved laboratory method does not exceed an average operating
turbidity of 2 turbidity units and does not exceed 5 turbidity units more than
5 percent of the time during any 24-hour period.
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(s) Disinfected Wastewater. Disinfected wastewater means wastewater in
which the pathogenic organisms have been destroyed by chemical, physical, or
biological means.
(t) Multiple Units. Multiple units mean two or more units of a treatment
process which operate in parallel and serve the same function.
(u) Standby Unit Process. A standby unit process is an alternate unit
process which is maintained in operable condition and which is capable of pro-
viding comparable treatment for the entire design flow in the event that the unit
for which it is a substitute becomes inoperative.
(v) Power Source. Power source means a source of supplying energy to
operate unit processes.
(w) Standby Power Source. Standby power source means an alternate
energy source such as an engine driven generator, maintained in immediately
operable condition and of sufficient capacity to provide necessary service during
failure of the normal power supply.
(x) Alarm. Alarm means an instrument or device which continuously
monitors a specific function of a treatment process and automatically gives
warning of an unsafe or undesirable condition by means of visual and audible
signals.
(y) Person. Person also includes any city, county, district, the State or
any department or agency thereof.
Article 2. Irrigation of Food Crops
8030. Spray Irrigation. Reclaimed water used for the spray irrigation
of food crops shall be at all times an adequately disinfected, oxidized, coagu-
lated, filtered wastewater. The wastewater shall be considered adequately dis-
infected if at some location in the treatment process the median number of
coliform organisms does not exceed 2. 2 per 100 milliliters and the number of
coliform organisms in any sample does not exceed 23 per 100 milliliters. The
median value shall be determined from the bacteriological results of the last 7
days for which analyses have been completed.
8031. Surface Irrigation, (a) Reclaimed water used for surface irriga-
tion of food crops shall be at all times an adequately disinfected, oxidized
wastewater. The wastewater shall be considered adequately disinfected if at
some location in the treatment process the median number of coliform orga-
nisms does not exceed 2. 2 per 100 milliliters, as determined from the bacteri-
ological results of the last 7 days for which analyses have been completed.
169
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(b) Orchards and vineyards may be surface irrigated with reclaimed water
that has the quality at least equivalent to that of primary effluent provided that no
fruit is harvested that has come in contact with the irrigating water or the ground.
8032. Exceptions. Exceptions to the quality requirements for reclaimed
water used for irrigation of food crops may be considered by the State Depart-
ment of Health on an individual case basis where the reclaimed water is to be
used to irrigate'a food crop which must undergo extensive commercial, physical,
or chemical processing sufficient to destroy pathogenic agents before it is suit-
able for human consumption.
Article 3. Irrigation of Fodder, Fiber, and Seed Crops
8035. Fodder, Fiber, and Seed Crops. Reclaimed water used for the
surface or spray irrigation of fodder, fiber, and seed crops shall have a level of
quality no less than that of primary effluent.
8036. Pasture for Milking Animals. Reclaimed water used for the irriga-
tion of pasture to which milking cows or goats have access shall be at all times
an adequately disinfected, oxidized wastewater. The wastewater shall be con-
sidered adequately disinfected if at some location in the treatment process the
median number of coliform organisms does not exceed 23 per 100 milliliters, as
determined from the bacteriological results of the last 7 days for which analyses
have been completed.
Article 4. Landscape Irrigation
8039. Landscape Irrigation. Reclaimed water used for the irrigation of
golf courses, cemeteries, lawns, parks, playgrounds, freeway landscapes, and
landscapes in other areas where the public has access shall be at all times an
adequately disinfected, oxidized wastewater. The wastewater shall be considered
adequately disinfected if at some location in the treatment process the median
number of coliform organisms does not exceed 23 per 100 milliliters, as deter-
mined from the bacteriological results of the last 7 days for which analyses have
been completed.
Article 5. Recreational Impoundments
8042. Non-Restricted Recreational Impoundment. Reclaimed water used
as a source of supply in a non-restricted recreational impoundment shall be at
all times an adequately disinfected, oxidized, coagulated, filtered wastewater.
The wastewater shall be considered adequately disinfected if at some location in
the treatment process the median number of coliform organisms does not exceed
170
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2. 2 per 100 milliliters and the number of coliform organisms in any sample does
not exceed 23 per 100 milliliters. The median value shall be determined from the
bacteriological results of the last 7 days for which analyses have been completed.
8043. Restricted Recreational Impoundment. Reclaimed water used as a
source of supply in a restricted recreational impoundment shall be at all times
an adequately disinfected, oxidized wastewater. The wastewater shall be con-
sidered adequately disinfected if at some location in the treatment process the
median number of coliform organisms does not exceed 2. 2 per 100 milliliters,
as determined from the bacteriological results of the last 7 days for which anal-
yses have been completed.
8044. Landscape Impoundment. Reclaimed water used as a source of sup-
ply in a landscape impoundment shall be at all times an adequately disinfected,
oxidized wastewater. The wastewater shall be considered adequately disinfected
if at some location in the treatment process the median number of coliform
organisms does not exceed 23 per 100 milliliters, as determined from the bac-
teriological results of the last 7 days for which analyses have been completed.
Article 6, Sampling and Analysis
8047. Sampling and Analysis, (a) Samples for settleable solids and coli-
form bacteria, where required, shall be collected at least daily and at a time
when wastewater characteristics (highest organic and hydraulic mass loading)
are most demanding on the treatment facilities and disinfection procedures.
Turbidity analysis, where required, shall be performed by a continuous record-
ing turbidimeter.
(b) For uses requiring a level of quality no less than that of primary efflu-
ent, samples shall be analyzed by an approved laboratory method for settleable
solids.
(c) For uses requiring an adequately disinfected, oxidized wastewater,
samples shall be analyzed by an approved laboratory method for coliform bac-
teria content.
(d) For uses requiring an adequately disinfected, oxidized, coagulated,
filtered wastewater, samples shall be analyzed by approved laboratory methods
for turbidity and coliform bacteria content.
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Article 7. Engineering Report and Operational Requirements
8050. Engineering Report, (a) No person shall produce or supply
reclaimed water as defined in Section 13050 (n) of the Water Code for direct
reuse from a proposed water reclamation plant unless he files an engineering
report in accordance with Water Code Section 13522.5.
(b) The report shall be prepared by a civil engineer registered in California
and experienced in the field of wastewater treatment, and shall contain a descrip-
tion of the design of the proposed reclamation system. The report shall clearly
indicate the means for compliance with these regulations and any other features
specified by the regulatory agency.
8051. Personnel, (a) Each reclamation plant shall be provided with suf-
ficient number of qualified personnel to operate the facility effectively so as to
achieve the required level of treatment at all times.
(b) Qualified personnel shall be those meeting requirements established
pursuant to Chapter 9 (commencing with Section 13625) of the Water Code.
8052. Maintenance. An equipment maintenance program shall be pro-
vided at each reclamation plant to ensure that all equipment is kept in a highly
reliable operating condition.
8053. Operational Records and Reports, (a) Operating records shall be
maintained at the reclamation plant or a centralized depository within the oper-
ating agency. These shall include all analyses specified in the reclamation
criteria and records of operational problems, plant and equipment breakdowns,
diversions to emergency storage or disposal, and all corrective or preventive
action taken.
(b) Process or equipment failures triggering an alarm shall be recorded
and maintained as a separate record file. The recorded information shall in-
clude the time and cause of failure and corrective action taken.
(c) A monthly summary of operating records as specified under (a) and
(b) in this section shall be filed monthly with the regulatory agency.
(d) Any discharge of untreated or partially treated wastewater to the use
area, and the cessation of same, shall be reported by telephone to the regula-
tory agency, the State Department of Health, and the local health officer.
8054. Bypass. There shall be no bypassing of untreated or partially
treated wastewater from the reclamation plant or any intermediate unit pro-
cesses to the point of use.
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Article 8. General Requirements of Design
8057. Flexibility of Design. The design of process piping, equipment
arrangement,, and unit structures in the reclamation plant must allow for effi-
ciency and convenience in operation and maintenance and provide flexibility of
operation to permit the highest possible degree of treatment to be obtained under
varying circumstances.
8058. Alarms, (a) Alarm devices required for various unit processes as
specified in other sections of these regulations shall be installed to provide warn-
ing of at least the following process failures:
(1) Loss of power from normal power supply,
(2) Loss of air supply or any other event which may result in failure
of a biological treatment process.
(3) Loss of chlorine supply, low chlorine residual, failure of injector
water supply, and any other event which may result in failure of a
disinfection process.
(4) Loss of coagulant feed and any other event which may result in
failure of a coagulation process.
(5) Excessive headloss, excessive turbidity, and any other event or
parameter which may result in failure of a filtration process.
(6) Any other specific process failure for which warning is required
by the regulatory agency.
(b) All required alarm devices shall be independent of the main power sup-
ply of the reclamation plant.
(c) The person to be warned shall be the plant operator, superintendent, or
any other responsible person designated by the management of the reclamation
plant and capable of taking prompt corrective action.
(d) Individual alarm devices may be connected to a master alarm to sound
at a location where it can be conveniently observed by the attendant. In case the
reclamation plant is not attended full time, alarm(s) shall be connected to sound
at a police station, fire station or other full time service unit with which arrange-
ments have been made to alert the person in charge at times that the reclama-
tion plant is unattended.
8059. Power Supply. Provisions shall be made for substitute power in the
event of failure of the normal power supply including one of the following relia-
bility features:
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(a) Alarm and standby power source, including automatic switchover to
self-starting standby power source if the plant will not be attended continuously.
(b) Alarm and automatically actuated short-term retention provisions for
untreated wastewater as specified in Section 8064.
(c) Automatically actuated long-term emergency storage or disposal pro-
visions for untreated wastewater as specified in Section 8064.
Article 9. Alternative Reliability Requirements for
Uses Permitting Primary Effluent
8061. Primary Treatment. Reclamation plants producing reclaimed water
exclusively for uses for which primary effluent is permitted shall be provided
with one of the following reliability features:
(a) Multiple or standby primary treatment units, as specified in Section
8064, capable of providing essentially unimpaired treatment when one unit is
taken out of service.
(b) Long-term emergency storage or disposal provisions as specified in
Section 8064.
Article 10. Alternative Reliability Requirements for Uses
Requiring Oxidized, Disinfected Wastewater or
Oxidized, Coagulated, Filtered, Disinfected
Wastewater
8064. Definitions Relating to Reliability Requirements, (a) Multiple
biological treatment units mean multiple tanks and multiple units of all critical
process equipment such as blowers, aerators, and recirculation pumps.
(b) Standby replacement equipment means reserve parts and equipment
such as pumps, valves, controls, and instruments to replace broken-down or
worn-out units which can be assembled and placed in operation within a 24-hour
period.
(c) Uninterrupted coagulant feed means all of the following mandatory
features: standby feeders, adequate chemical storage and conveyance facilities,
adequate reserve chemical supply, automatic dosage control, and alarms to warn
of equipment breakdown.
(d) Uninterrupted chlorine feed means the following mandatory features:
standby chlorine supply, manifold systems to connect chlorine cylinder scales;
alarms to warn of malfunctions, automatic devices for switching over to full
174
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chlorine cylinders, and in addition may require automatic residual control of
chlorine dosage, automatic measuring and recording of chlorine residual, and
hydraulic performance studies.
(e) A standby chlorinator means a duplicate chlorinator for reclamation
plants having one chlorinator; duplicate of the largest unit for plants having mul-
tiple chlorinator units. All standby equipment shall be maintained in immediate
operable condition.
(f) Multiple point chlorination means that chlorine will be applied simul-
taneously at the reclamation plant and at subsequent chlorination stations located
at the use area and/or some intermediate point. It does not include chlorine
application for odor control purposes.
(g) Where short-term retention is provided as a reliability feature, it
shall consist of facilities reserved for the purpose of storing or disposing of
untreated or partially treated wastewater for at least a 24-hour period. The
facilities shall include all the necessary diversion devices, provisions for odor
control, conduits and pumping and pump back equipment, and shall be either
independent of normal power or provided with a standby power source.
(h) Where long-term emergency storage or disposal provisions are used as
a reliability feature, these shall consist of ponds, reservoirs, percolation areas,
downstream sewers leading to other treatment or disposal facilities or any other
facilities reserved for the purpose of emergency storage or disposal of untreated
or partially treated wastewater. These facilities shall be of sufficient capacity
to provide disposal or storage of wastewater for at least 20 days, and shall
include all the necessary diversion works, provisions for odor and nuisance con-
trol, conduits and pumping and pump back equipment. The emergency equipment
shall be either independent of normal power or provided with a standby power
source.
(1) Diversion to a less demanding reuse is an acceptable alternative
to emergency disposal of partially treated wastewater provided that the
quality of the partially treated wastewater is suitable for the less demanding
reuse.
(2) Subject to prior approval by the regulatory agency, diversion to a
discharge point which requires lesser quality of wastewater is an acceptable
alternative to emergency disposal of partially treated wastewater.
(3) Automatically actuated long-term emergency storage or disposal
provisions shall include, in addition to provisions of part (h) of this section,
or parts (1) or (2) of this subsection, all the necessary sensors, instru-
ments, valves and other devices to enable fully automatic diversion of un-
treated or partially treated wastewater to approved emergency storage or
disposal in the event of failure of a treatment process, and a manual reset
to prevent automatic restart until the failure is corrected.
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(i) Multiple or standby primary treatment units mean multiple or standby
tanks and multiple or standby units of all critical process equipment such as
sludge transfer facilities.
8065. Primary Effluent. All primary treatment unit processes shall be
provided with one of the following reliability features:
(a) Multiple units to enable partial treatment of wastewater with one unit
not in operation.
(b) Standby primary treatment unit process.
(c) Long-term emergency storage or disposal provisions.
8066. Biological Treatment. All biological treatment unit processes shall
be provided with one of the following reliability features:
(a) Alarm and multiple biological treatment units capable of producing
oxidized, wastewater with one unit not in operation.
(b) Alarm, short-term retention provisions, and standby replacement
equipment.
(c) Alarm and long-term emergency storage or disposal provisions.
(d) Automatically actuated long-term emergency storage or disposal
provisions.
8067. Secondary Sedimentation. All secondary sedimentation unit pro-
cesses shall be provided with one of the following reliability features:
(a) Multiple sedimentation units capable of providing essentially unimpaired
treatment when one unit is taken out of service.
(b) Standby sedimentation unit process.
(c) Long-term emergency storage or disposal provisions.
8068. Coagulation. All coagulation unit processes shall be provided with
special provisions for uninterrupted coagulant feed and one of the following reli-
ability features:
(&) Alarm and multiple coagulation units capable of treating the entire flow
with one unit not in operation.
(b) Alarms short-term retention provisions and standby replacement
equipment.
176
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(c) Alarm and long-term emergency storage or disposal provisions.
(d) Automatically actuated long-term emergency storage or disposal
provisions.
(e) Alarm and standby coagulation unit process.
8069. Filtration. All filtration unit processes shall be provided with one
of the following reliability features:
(a) Alarm and multiple filter units capable of treating the entire flow with
one unit not in operation.
(b) Alarm, short-term retention provisions and standby replacement
equipment.
(c) Alarm and long-term emergency storage or disposal provisions.
(d) Automatically actuated long-term emergency storage or disposal
provisions.
(e) Alarm and standby filtration unit process.
8070. Disinfection. All disinfection unit processes where chlorine is used
as the disinfectant shall be provided with features for uninterrupted chlorine feed
and one of the following reliability features:
(a) Alarm and standby chlorinator.
(b) Alarm, short-term retention provisions and standby replacement
equipment.
(c) Alarm and long-term emergency storage or disposal provisions.
(d) Automatically actuated long-term emergency storage or disposal
provisions.
(e) Alarm and multiple point chlorination, each with independent power
source, separate chlorinator, and separate chlorine supply.
8071. Other Alternatives to Reliability Requirements. Other alternatives
to reliability requirements set forth in Articles 8 to 10 may be accepted if the
applicant demonstrates to the satisfaction of the regulatory agency that the pro-
posed alternative will assure an equal degree of reliability.
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Article 11. Other Methods of Treatment
8072. Other Methods of Treatment. Methods of treatment other than those
included in this chapter and their reliability features will be evaluated by the
regulatory agency on a case-by-case basis.
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Appendix F
SOURCES OF DATA
To assist the evaluator and engineer in data-gathering and evaluation, some
major sources of data are listed for climate, topography, soil characteristics,
geologic formations, groundwater, and receiving water. It must be stressed
that these do not represent all the possible sources of data.
CLIMATE
Information on precipitation, temperature, humidity, and winds maybe obtained
from the following sources:
National Weather Service, local offices
Climatological Data, published by the National Weather Service,
Department of Commerce
Airports
Universities
Military installations
The National Oceanographic and Atmospheric Administration is preparing a
report for EPA on weather parameters that influence winter operations of land-
application systems. This report, when available in early 1975, should be an
excellent source of climatological data.
Additionally, data on evapotranspiration can usually be obtained from the follow-
ing sources:
Agricultural Extension Service
Agricultural Experiment Stations
Agencies managing large water reservoirs
TOPOGRAPHY
Topographic maps and aerial photographs can provide much of the information
needed to analyze the topography. Topographic maps are most widely available
from the U. S. Geological Survey in 7. 5- and 15-minute quadrangles. Aerial
photographs, when they exist, may be located by contacting the following sources:
179
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U.S. Department of Agriculture, Commodity Stabilization program
Local or county planning departments
U.S. Corps of Engineers offices
Private photogrammetry and mapping companies
SOIL CHARACTERISTICS
Consultation with the Soil Conservation Service (U. S. Department of
Agriculture) to obtain information on soil characteristics is highly recom-
mended. SCS offices exist in most counties; however, each county office does
not necessarily have a soil scientist. The state soil scientists should therefore
be contacted. Additionally, SCS has published many soil maps with descriptions
of soil characteristics to a depth of 5 feet. These descriptions include ground-
slopes, existing land use, erosion potential, and surface drainage, which are also
important considerations. Agricultural Extension Service representatives, con-
sulting soil scientists, or agronomists may have additional information on soil
characteristics.
GEOLOGIC FORMATIONS
The U.S. Geological Service is the primary source of data on geological forma-
tions. Geologic maps and investigative reports are available for many areas.
State mine and geology agencies may also have information on geologic forma-
tions in terms of maps or reports.
GROUNDWATER
Data on groundwater may come from a number of different sources, such as
state water resource agencies, the U.S. Geological Service, local or county
water conservation districts, and users of groundwater (municipalities, water
companies, and individuals).
RECEIVING WATER
The U. S. Geological Service has monitoring gages on most large streams and
many small ones. In addition to this flow data, data on temperature and mineral
quality are collected. The EPA has a computer storage system (called STORET)
that contains a great deal of water-quality data from one-time studies and con-
tinuous monitoring by federal, state, and local agencies. STORET output can
be obtained at Regional EPA offices.
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Appendix G
COST-EFFECTIVENESS ANALYSIS GUIDELINES
(40 CFR 35 - Appendix A)
Title 40Protection of the Environment
CHAPTER IENVIRONMENTAL
PROTECTION AGENCY
SUBCHAPTER DGRANTS
PART 35STATE AND LOCAL
ASSISTANCE
Appendix ACost-Effectiveness Analysis
On July 3, 1973, notice was published
in the FEDERAL REGISTER that the En-
vironmental Protection Agency was pro-
posing guidelines on cost-effectiveness
analysis pursuant to section 212(2) (c) of
the Federal Water Pollution Act Amend-
ments of 1972 (the Act) to be published
as' appendix A to 40 CFR part 35.
Written comments on the proposed
rulemaking were invited and received
from interested parties. The Environ-
mental Protection Agency has carefully
considered all comments received. No
changes were made in the guidelines as
earlier proposed. All written comments
are on file with the agency.
Effective date.These regulations shall
become effective October 10, 1973.
Dated September 4, 1973.
JOHN QTJARLES,
Acting Administrator.
APPENDIX A
COST EFFECTIVENESS ANALYSIS GUIDELINES
a. Purpose.These guidelines provide a
basic methodology for determining the most
cost-effective waste treatment management
system or the most cost-effective component
part of any waste treatment management
system.
b. Authority.The guidelines contained
herein are provided pursuant to section 212
(2) (C) of the Federal Water Pollution Con-
trol Act Amendments of 1972 (the Act).
c. Applicability.These guidelines apply
to- the development of plans for and the
selection of component parts of a waste
treatment management system for which a
Federal grant is awarded under 40 CFR,
Part 35.
d. Definitions.Definitions of terms used
in these guidelines are as follows:
(1) Waste treatment management sys-
tem.A system used to restore the integrity
of the Nation's waters. Waste treatment
management system is used synonymously
with "treatment works" as defined in 40
CFR, Part 35.905-15.
(2) Cost-effectiveness analysis.An analy-
sis performed to determine which waste
treatment management system or compo-
nent part thereof will result in the minimum
total resources costs over time to meet the
Federal, State or local requirements.
(3) Planning period.The period over
which a waste treatment management sys-
tem is evaluated for cost-effectiveness. The
planning period commences with the initial
operation of the system.
(4) Service life.The period of time dur-
ing which a component of a waste treat-
ment management system will be capable of
performing a function.
(5) Use/ul life.The period of time dur-
ing which a component of a waste treat-
181
ment management system will be required to
perform a function which Is necessary to
the system's operation.
e. Identification, selection and screening
of alternatives(1) Identification of alter-
natives.All feasible alternative waste man-
agement systems shall be Initially identified.
These alternatives should include systems
discharging to receiving waters, systems
using land or subsurface disposal techniques,
and systems employing the reuse of waste-
water. In identifying alternatives, the possi-
bility of staged development of the system
shall be considered.
(2) Screening of alternatives.The iden-
tified alternatives shall be systematically
screened to define those capable of meeting
the applicable Federal, State, and local
criteria.
(3) Selection of alternatives.The
screened alternatives shall be initially ana-
lyzed to determine which systems have cost-
effective potential and which should be fully
evaluated according to the cost-effectiveness
analysis procedures established in these
guidelines.
(4) Extent of effort.The extent of effort
and the level of sophistication used in the
cost-effectiveness analysis should reflect the
size and importance of the project.
f. Cost-Effective analysis procedures(1)
Method of Analysis.The resources costs
shall be evaluated through the use of oppor-
tunity costs. For those resources that can be
expressed in monetary terms, the interest
(discount) rate established in section (f) (5)
will be used. Monetary costs shall be calcu-
lated in terms of present worth values or
equivalent annual values over the planning
period as denned in section (f) (2). Non-
monetary factors (e.g., social and environ-
mental) shall be accounted for descriptively
in the analysis in order to determine their
significance and impact.
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The most cost-effective alternative shall be
the waste treatment management system
determined from the analysis to have the
lowest present worth and/or equivalent an-
nual value without overriding adverse non-
monetary costs and to realize at least identi-
cal minimum benefits in terms of applicable
Federal, State, and local standards for ef-
fluent quality, water quality, water reuse
and/or land and subsurface disposal.
(2) Planning period.The planning period
for the cost-effectiveness analysis shall be 20
years.
(3) Elements of cost.The costs to be
considered shall Include the total values of
the resources attributable to the waste treat-
ment management system or to one of Its
component parts. To determine these values,
all monies necessary for capital construction
costs and operation and maintenance costs
shall be Identified.
Capital construction costs used in a cost-
effectiveness analysis shall include all con-
tractors' costs of construction including over-
head and profit; costs of land, relocation, and
right-of-way and easement acquisition;
design engineering, field exploration, and en-
gineering services during construction; ad-
ministrative and legal services including
costs of bond sales; startup costs such as op-
erator training; and interest during con-
struction. Contingency allowances consistent
with the level of complexity and detail of the
cost estimates shall be Included.
Annual costs for operation and mainte-
nance (including routine replacement of
equipment and equipment parts) shall be
Included in the cost-effectiveness analysis.
These costs shall be adequate to ensure ef-
fective and dependable operation during the
planning period for the system. Annual costs
shall be divided between fixed annual costs
and costs which would be dependent on the
annual quantity of wastewater collected and
treated.
(4) Prices.The various components of
cost shall be calculated on the basis of mar-
ket prices prevailing at the time of the cost-
effectiveness analysis. Inflation of wages and
prices shall not be considered in the analysis.
The implied assumption is that all prices
involved will tend to change over time by
approximately the same percentage. Thus,
the results of the cost effectiveness analysis
will not be affected by changes in the gen-
eral level of prices.
Exceptions to the foregoing can be made
If their is Justification for expecting signifi-
cant changes in the relative prices of certain
items during the planning period. If such
cases are identified, the expected change in
these prices should be made to reflect their
future relative deviation from the general
price level.
(5) Interest (discount) rate.A rate of 7
percent per year will be used for the cost-
effectiveness analysis until the promulgation
of the Water Resources Council's "Proposed
Principles and Standards for Planning Water
and Related Land Resources." After promul-
gation of the above regulation, the rate
established for water resource projects shall
be used for the cost-effectiveness analysis.
(6) Interest during construction.In cases
where capital expenditures can be expected
to be fairly uniform during the construction
period, interest during construction may be
calculated as IX % PXC where:
I=the interest (discount) rate in. Section
P=the construction period in years.
C=the total capital expenditures.
In cases when expenditures will not be
uniform, or when the construction period
will be greater than three years, Interest dur-
ing construction shall be calculated on a
year-by-year basis.
(7) Service life. The service life of treat-
ment works for a cost-effectiveness analysis
shall be as follows:
Land _________________________ Permanent
Structures ____________________ 30-60 yeaA
(Includes plant buildings,
concrete process tankage,
basins, etc.; sewage collec-
tion and conveyance pipe-
lines; lift station struc-
tures; tunnels; outfalls)
Process equipment _____________ 16-30 years
(includes major process
equipment such as clarlfler
mechanism, vacuum niters,
etc.; steel process tankage
and chemical storage facili-
ties; electrical generating
facilities on standby service
only).
Auxiliary equipment ___________ 10-15 years
(Includes instruments and
control facilities; sewage
pumps and electric motors;
mechanical equipment such
as compressors, aeration sys-
tems, centrifuges, chlori-
nators, etc.; electrical gen-
erating facilities on regular
service) .
Other service life periods will be acceptable
when sufficient Justification can be provided.
Where a system or a component Is for
interim service and the anticipated useful
life is less than the service life, the useful
life shall be substituted for the service life of
the facility in the analysis.
(8) Salvage value. Land for treatment
works, Including land used as part of the
treatment process or for ultimate disposal of
residues, shall be assumed to have a salvage
value at the end of the planning period equal
to its prevailing market value at the time of
the analysis. Right-of-way easements shall
be considered to have a salvage value not
greater than the prevailing market value at
the time of the analysis.
Structures will be assumed to have a
salvage value if there is a use for such struc-
tures at the end of the planning period. In
this case, salvage value shall be estimated
using straightline depreciation during the
service life of the treatment works.
For phased additions of process equipment
and auxiliary equipment, salvage value at the
end of the planning period may be estimated
under the same conditions and on the same
basis as described above for structures.
When the anticipated useful life of a facil-
ity Is less than 20 years (for analysis of in-
terim facilities) , salvage value can be claimed
for equipment where It can be dearly dem-
onstrated that a specific market or reuse
opportunity will exist.
[FR Doc.73-I9104 Piled 9-7-73:8:45 am]
FEDERAL REGISTER, VOL. 38, NO. 174MONDAY, SEPTEMBER 10, 1973
182
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