EPA-600/9-76-014
July 1976
AREAWIDE ASSESSMENT
PROCEDURES MANUAL
VOLUME I
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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MANUAL DISTRIBUTION RECORD
The Areawide Assessment Procedures Manual is prepared as one of a number
of information documents developed to support the Agency's 208 areawide
waste treatment management and planning effort. The complete Manual is
presented in a three volume format to facilitate its use. Because the
Manual is being prepared and distributed in separate mailings, and because
it is anticipated that some chapters or appendices will be revised in the
future, it is necessary that the recipient of this portion of the Manual
enter a "Register of Manual Users."
In order for your name to be entered into the Register and therefore be
placed on the mailing list for future Manual additions and/or revisions,
the accompanying form, EPA-291(Gin)(7/76), must be filled out. The correct
information must be entered into the following blocks of the Form:
TITLE (Dr., Mr., Ms., etc.), LAST NAME (Omit professional titles), FIRST
NAME, I (i.e., middle initial), COMPANY NAME, ADDRESS LINES ONE, TWO, THREE
(i.e., company address), CITY, ST (acceptable 2-character state abbreviation),
and ZIP, (must be entered).
The completed form should then be sent to:
Computer Services Systems Division
U. S. Environmental Protection Agency
26 West St. Clair Street
Cincinnati, Ohio 45268
Attn: Ms. Brenda Wagner, Rm. 308
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
TO: User of the Areawide Assessment Procedures Manual
With the completion of this mailing of the Areawide Assessment Procedures
Manual, it is appropriate to review the contents of the three volumes
which comprise a complete Manual. By so doing, we can reconcile what was
originally proposed in Chapter 1 as the tentative contents of the Manual
with the chapters and appendixes which you actually received.
The discussion of the Manual's content in Chapter 1 was prepared at
that point in time when details for the preparation of following
sections of the Manual had not been finalized. Subsequently, as the
later chapters and appendixes were being drafted, modifications to
the proposed contents were deemed expedient and the final product is
a slightly different but uncompromised version of the Manual that
was originally and tentatively outlined. The changes, in fact, have
facilitated the continuity of content, data presentation, and format.
The contents of the Areawide Assessment Procedures Manual, specified
as to placement in volume I, II, or III, and the chapter or appendix
"\, title are as follows:
J
Volume Title
I (Preface material)
I Chapter 1 - Introduction
I Chapter 2 - Preliminary Problem Assessment
I Chapter 3 - Procedures for Assessment of Urban Pollutant
Sources and Loadings
I Chapter 4 - Assessment of Nonurban, Non-point Pollutant
Sources and Loadings
I Chapter 5 - Analysis of Stream Impacts for Urban and
Nonurban Sources
I Chapter 6 - Evaluation and Selection of Control Alternatives
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Volume Title
II Appendix A - Model Applicability Summary
II Appendix C - Land Use Data Collection and Analysis
II . Appendix D - Monitoring Requirements, Methods, and Cost
Appendix D, Part II - Parameter Handbook
II Appendix E - Documentation for Synoptic Rainfall Data
Analysis Program - SYNOP
III Appendix G, Part I - Urban Stormwater Management Techniques:
Performance and Cost
Appendix G, Part II - "Storm Water Management Model"
Report No. EPA-600/2-77-083
III Appendix H - Point Source Control Alternatives: Performance
and Cost
III Appendix I - Bibliography
III Appendix J - Glossary
Chapter 7, Examples of Assessment Methodology for Urban and Non-Urban Areas;
Appendix B, Water Quality Data Bases; and Appendix E, Water Quality Standards,
which were first described in Chapter 1 have been deleted from the contents of
the Manual. Due to'the increased pressure of the time frame required by the
planning cycle, and the reevaluation of priorities which was made as work on
other parts of the Manual progressed, the decision was made to concentrate
on the most critical remaining sections. As a result, the three sections
specified above were not prepared, nor will they be in the immediate future.
Therefore, the Areawide Assessment Procedures Manual, as described above by
volume and text title, is complete.
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DISCLAIMER
This manual has been reviewed by the Office of Research and Development
(Municipal Environmental Research Laboratory - Cincinnati, and Environmental
Research Laboratory - Athens) and by the Office of Water and Hazardous
Materials (Water Planning Division) and is approved for publication.
In approving the first edition of this manual both the Office of Water and
Hazardous Materials and the Office of Research and Development emphasize
that the information contained herein represents a summarization of selected
state-of-the-art assessment procedures and impact analysis techniques that
are considered useful and supportive of the objectives of the areawide
wastewater planning and management programs.
The contents of the manual are intended to be informative rather than
prescriptive in nature and in no way should be considered mandatory. Approval
does not signify that the contents necessarily reflect the views of the
Environmental Protection Agency nor does mention of trade names or propriety
approaches constitute endorsement or recommendation for use.
ii
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\
18 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
TO: Users of the Areawide Assessment Procedures Manual
The implementation of State and areawide planning under Section 208 of
P.L. 92-500 has created a demand for sound technical analyses within a
relatively short period of time. As new information becomes available
from research efforts, it is important that it be applied where possible
to our environmental management efforts. This manual was produced as a
joint effort between EPA's Office of Research and Development and the
Office of Water Planning and Standards. It provides a statement of
procedures available for water quality management, with particular
emphasis on urban stormwater. This publication contains the first
sections of a manual that will be mailed in three parts. This first
mailing includes a description of some of the basic procedures which
could be utilized during the early stages of a study to determine whether
more complex analyses are warranted.
As point sources are abated, an increased concern has developed on the
need for controlling nonpoint sources of pollution. For effective water
quality management, it is often necessary to analyze the relative contribution
of different pollution sources so that coordinated structural and non-
structural control programs can be proposed. This manual suggests
procedures which should lead to practical decisions, based on the assumption
that the simplest techniques can often produce the necessary information
that is to be used. Thus the manual describes several techniques which
are representative of different levels of sophistication which may be
required for both problem assessment and the evaluation of alternatives.
The implementation of environmental programs requires both a sound
technical justification as well as local political support; therefore,
the desirable plan may not necessarily represent the optimal solution in
the strictest sense, but rather a pragmatic solution which will be
inip^ented and result in improved or preserved water quality.
'Beck Thomas Murphy (
Deputy Assistant Administrator Deputy Assistant Administrator
for Water Planning & Standards for Air, Land, and Water Use
111
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ABSTRACT
This manual summarizes and presents in condensed form a range of available
procedures and methodologies that are available for identifying and-
estimating pollutant load generation and transport from major sources
within water quality management planning areas. Although an annotated
chapter is provided for the assessment of non-urban pollutant loads, the
major emphasis of the manual is directed toward the assessment of
problems and selection of alternatives in urban areas, with particular
concern for stormwater related problems. Also included in the manual are
methodologies for assessing the present and future water quality impacts
from major sources as well as summaries of available information and
techniques for analysis and selection of structural and non-structural
control alternatives.
This manual is structured to present problem assessment and impact analysis
approaches for several levels of planning sophistication. Simple procedures
are recommended for initial analysis to develop the insight and problem
understanding to guide the application of more complex techniques where
required.
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FOREWORD
The enactment of Public Law 92-500 marked a new era of environmental
awareness in the United States. A vital part of this legislation is the
provision for areawide waste treatment management planning under Section 208.
The Congressional intent of Section 208 was to establish a planning frame-
work necessary to meet the 1983 National Water Quality Goals in highly
urbanized areas or non-urban environments where complex water quality
problems exist.
In establishing an overall wastewater management plan, state and areawide
planning agencies must examine the wide variety of pollutant sources and
corresponding receiving water impacts in the planning area in light of
the necessity and feasibility of their control. The most successful
approach will likely be one that integrates ongoing and projected point
source pollution control measures with cost-effective combinations of
management and structural alternatives for nonpoint source pollution control.
This Areawide Assessment Procedures Manual, produced jointly by EPA's Water
Planning Division and Office of Research and Development, is one of a
number of guidance and information documents developed to support the Agency's
208 areawide waste treatment management and planning effort. The manual
summarizes selected state-of-the-art problem assessment methodologies and
approaches that are useful in achieving the goals and objectives of state
and areawide water quality management and planning. Future editions of this
manual are planned as new areawide assessment procedures and methodologies
are further developed and verified.
Francis T. Mayo
Director
Municipal Environmental Research
Laboratory
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ACKNOWLEDGEMENTS
This manual has been prepared by the Environmental Protection Agency,
Office of Research and Development, Municipal Environmental Research
Laboratory, Cincinnati, in collaboration with the Office of Water and
Hazardous Materials, Water Planning Division. Significant technical
contribution and direction has been provided by the following EPA programs:
- Environmental Research Laboratory, Office of Air, Land and Water
Use, Athens, Georgia.
- Environmental Monitoring and Support Laboratory, Office of
Monitoring and Technical Support, Las Vegas, Nevada.
In addition to EPA staff contributions, portions of this manual have also
been prepared in whole or in part by the organizations listed below:
- Hydroscience, Inc., Westwood, New Jersey.
- Battelle Columbus Laboratories, Columbus, Ohio.
- Roy F. Weston, Inc., West Chester, Pennsylvania.
- EG§G Washington Analytical Services Center, Inc., Rockville, Maryland.
- Metcalf $ Eddy, Inc., Palo Alto, California.
vi
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CHAPTER 1
INTRODUCTION
1.1 Purpose of the Manual
When Congress passed the Federal Water Pollution Control Act Amendments of
1972 (the Act), it was recognized that a number of water pollution control
problems in the United States are so complex that they cannot be solved by
traditional engineering evaluation and technology application alone. In most
cases, these problems involve urban areas where population and industry are
concentrated and where inter-relationships exist between receiving water
quality, point source discharges, intermittent point loads from combined sewer
overflows, and urban stormwater runoff. The situation may be further compli-
cated and sometimes dominated by nonpoint source contaminant contributions from
rural areas outside of the urban fringe, or by the receiving water impacts of
construction activities, mining, or residuals management practices.
Section 208 of the Act provides a mechanism for the planning and management
necessary to achieve the 1983 goals in these complex regional situations. The
purpose of Section 208 is to facilitate the development and implementation of
areawide waste management plans at the local level in designated areas and by
the state outside such areas. As of September 1976, Federal assistance funds
have been provided at 75 to 100 percent of eligible project costs to 176 des-
ignated planning agencies for the preparation of initial areawide plans ad-
dressing the complex issues.
Early in the water quality management planning program, which began with the
award of the first grants in the Spring of 1974, a strong need developed at
the designated agency level for technical assistance in the assessment of
pollutant loads, receiving water impacts and control alternatives, particularly
with regard to nonpoint and intermittent point source loads in the urban en-
vironment. As more planning agencies have entered the 208 program, this need
has increased even more, in spite of the experience gained by early groups.
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To a large degree, the need results from the hydrologic and pollutant
generation complexity of urban areas. Each situation is unique, requiring
a range of analytic approaches which cannot necessarily be transported
from one study area to another. But the major problem has been the fact
that there is no established technical framework for analysis of
complicated urban wastewater problems. A wide range of methodologies
from many sources exists, but many of these are inappropriately applied in
planning programs at the sacrifice of time, expense, manpower and plan
accuracy.
The objective of this Areawide Assessment Procedures Manual is to provide
a unified technical framework for the analysis of complex areawide waste-
water problems. A range of useful assessment approaches is evaluated and
arrayed within this framework. To the greatest extent possible, an
attempt has been made to consolidate selected state-of-the-art information
into a single guide. The document stresses approaches to urban problems,
but also discusses assessment methodologies for non-urban, nonpoint source
pollution problems to the extent needed to put these problems into
relative perspective in the overall areawide waste treatment plan. Methods
for evaluating the receiving water impact and economic feasibility of
alternative pollution control strategies, including non-structural management
practices for urban stormwater control, are also provided.
It is especially important to understand that the Areawide Assessment
Procedures Manual does not present a required methodology or suggest
administrative planning procedures which must be followed. It is a
technical assistance and reference document intended for use by designated
local planning agencies, state planning bodies and planning and engineering
firms involved in areawide waste treatment management planning. It will
also be useful to municipal agencies concerned with stormwater management.
The discussion and evaluation of selected present day pollution assessment
methods, models, etc., here does not mean that other techniques are not
equally useful. The manual will be regularly updated as new techniques
are developed and as the results of practical application become available.
It is -also important to recognize that the document does not specifically
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concern itself with the institutional, political or legal aspects of area-
wide waste management planning. These are the subject of other assistance
documents soon to be published by the EPA Water Planning Division, Office
of Water and Hazardous Materials.
1.2 Relationship of the Manual to Agency Policy, Legal and Regulatory
Requirements and Guidance Documents
In assuming its responsibilities for the implementation of the Act, the
Environmental Protection Agency has published regulationsj policies and
guidance documents on water pollution abatement for use by individuals
in the private sector and by responsible public officials. While the
Areawide Assessment Procedures Manual is not an administrative policy or
regulations document, it is important for those who will use it in area-
wide water quality management planning to understand its relationship to
the requirements of such documents. This is particularly true in regard
to the question of urban stormwater management policy, which may be less
well understood by state and local planners than the more familiar require-
ments for point source control, effluent limitations, or funding requirements
for state and local 208 grants. Several recent developments regarding this
policy are discussed briefly below, with special emphasis upon those
policies affecting the potential need for application of the assessment
procedures of this manual.
1.2.2 Stormwater Management Policy
As the Nation's point source pollution control program nears the end of
its first stage, it is becoming more apparent that trade-offs must be made
between more advanced treatment of continuous point sources and control of
nonpoint source pollution. Among diffuse sources of pollution, stormwater
runoff has been identified as one of the major contributors to water
pollution in urban areas. Although treatment technology is available for
managing the stormwater problem, estimated National costs for implementation
of such treatment are prohibitive, ranging from $153 billion to $600 billion.
There is little doubt that there may be substantial inaccuracy in these
figures. This results from the variability of costing approaches and
treatment efficiency assumptions used, and the fact that, in spite of a
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variety of past assessment studies, the total relationship between urban
runoff and receiving water quality is not clearly understood. Nonetheless,
it is clear that alternatives other than traditional forms of treatment
should be considered.
A more effective approach for stormwater pollution abatement in urban areas
is the implementation of nonstructural stormwater management practices in
coordination with only the most cost-effective structural control options.
This approach may offer pollution abatement potential similar to the
various treatment alternatives available, but at a significantly reduced
cost.
Stormwater management practices, often termed Best Management Practices
(BMPs) fall into two groups: those most useful for existing or developed
areas and those more applicable to new or developing areas. In the former
instance, BMP embodies "reduction" techniques such as street sweeping,
improved waste collection and improved sewer maintenance practices and
sewer system management practices to reduce or attenuate stormwater flows
to receiving waters. A preventative concept best applies to developing
urban areas where the objective should be to manage new development in
order to contain or attenuate runoff flows and limit the potential for
unnatural pollutant contribution to receiving waters. Techniques in
these areas include improved construction site management; provision for
groundwater recharge; construction of detention basins; and playground,
parking lot, or rooftop storage of stormwater.
1.2.3 Funding and Legal Requirements
The need for the thorough development of comprehensive urban/areawide
wastewater management plans has been amplified by a recent court action
and by the Agency's further interpretation of stormwater regulations.
As a result of a June 10, 1975, decision of the Federal District Court
for the District of Columbia (NRDC versus Train) the Agency is required
to apply the National Pollutant Discharge Elimination System (NPDES)
permit program to separate storm sewers. Regulations for implementing this
decision were finalized in December 1975 (40 FR 56932). In accordance with
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these regulations certain storm sewers that were once exempt due to nonpoint
source status are now considered point sources, for which general permits
will be issued. In addition, respective permitting authorities may on
a case-by-case basis require the owner-operator of any separate storm
sewer to obtain a conventional NPDES permit.
Under these new regulations it has become increasingly important that urban
runoff from separate storm sewers be adequately included as a part of the
areawide planning process. It is also important for planners to realize
that the regulations have expanded the definition of a "separate storm
sewer" to mean "a conveyance or system of conveyances (including but not
limited to pipes, conduits, ditches and channels) located in an urbanized
area and primarily operated for the purpose of collecting and conveying
stormwater runoff." (Title 40, Chapter 1, Part 124, Part 125, Federal
Register, Vol. 41, No. 54, May 18, 1976).
The Agency has also provided policy direction regarding the use of
construction grants for providing treatment and control of combined
sewer overflows and stormwater discharges during wet-weather conditions.
This policy has significant implications upon the degree of stormwater
analysis conducted in 208 planning and upon the nature of stormwater
control alternatives proposed in the final water quality plan.
Construction grant funds may be approved for the control of pollution from
combined sewer overflows, but only after thorough, detailed wastewater
treatment planning for the 20-year planning interval has been completed
and has adequately considered the following:
(1) the effectiveness of alternative control techniques or management
practices,
(2) the costs of achieving various levels of pollution control with
each feasible technique,
(3) the benefits to the receiving waters of a range of levels of
pollution control during wet-weather conditions, and
(4) the costs and benefits resulting from the addition of advanced
waste treatment processes to dry-weather flows in that area.
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Where detailed areawide planning has been completed, treatment or control
of wet-weather overflows and by-passes may be given priority for construction
grant funds only after provision has been made for secondary treatment of
dry-weather flows in the area. For control or treatment of separate
discharges of stormwater, however, the Agency's current policy is that
construction grants shall not be available except under unusual conditions
where a project situation has clearly been shown to meet the detailed
planning and evaluation criteria for combined sewer overflow grants.
Projects with multiple purposes in addition to pollution control, such as
flood control and recreation, may be eligible for grant amounts not to
exceed the cost of the most cost-effective single pollution abatement
system.
1.2.4 Relationship to Other Technical Guidance Documents for
Areawide Planning
This Areawide Assessment Procedures Manual is one of several publications
issued or in preparation to assist the Water Planning Division of the
EPA Office of Water and Hazardous Materials to provide technological
guidance and information to those involved in areawide water quality
management planning.
A distinguishing feature of this manual is that it is more comprehensive
in scope than many of the previously issued assistance documents. It
represents the first of a series of information documents to be issued
for use in technical 208 planning efforts which will also include management
practice guidelines and pollution assessment methods for mining activities,
non-irrigated agriculture, silviculture, hydrographic modifications,
construction activities, and residuals management practices. These documents
are currently in preparation.
1.3 Guide for Use of the Manual
1.3.1 Intended Users
The Areawide Assessment Procedures Manual is intended 1:o be used as a
comprehensive technical reference and planning assistance document for use-
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by a wide range of individuals involved with various stages of the 208
planning process. The potential user community includes: administrators,
planning directors and technical planners at designated 208 agencies; state
environmental quality officials and individuals responsible for statewide
208 plans; private firms providing consulting services to 208 planning
efforts; Federal and state officials responsible for the review and
evaluation of areawide plans; and other public institutions responsible
for the management of urban drainage systems.
This is not to imply that the ..entire manual will be equally useful to all
people. Various portions will be useful to each of these groups at various
stages of the planning cycle. The manual does not have to be read from
cover to cover to be of use in the planning process.
For those designated local agencies in the formative stages of their
planning program, the preliminary assessment concepts, technical reference
material and cost information throughout the document will be very helpful.
Planning directors or administrators will probably find the preliminary
problem assessment sections of greatest use, especially in the sense that
problem identification in the early project stages will help clarify
staffing needs, suggest more efficient allocation of limited resources
among highest priority problems, and assist in the generation of an
effective work approach. Technical planners, engineers and consultants
on the other hand will have a greater interest in the assessment methods,
evaluation sections, and the Appendix information.
It is fully recognized that the utility of the manual will also vary from one
planning organization to another depending upon its stage in the planning
process and its regional environmental planning approach. Overall, the
manual will have the greatest impact upon those groups who are still
developing their approach to assessing urban/areawide water quality
problems. Organizations nearing completion of their 208 plans, or those
with well established comprehensive regional assessment approaches will
make greater use of the sections dealing with advanced assessment methods,
the evaluation of alternative control strategies, and management practices
for urban stormwater control. For those designated agencies already
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contractually committed to a particular planning direction the information
throughout the manual will enable more effective technical communication
with and direction of their consulting organizations.
1.4 Organization of the Manual
1.4.1 Rationale of Approach
An acknowledged fact of areawide planning is that the problems and needs
of no two planning areas are exactly the same. Similarly, problems within
a planning area have varying degrees of priority and complexity. Conse-
quently, there is no universally applicable assessment tool for the
analysis and solution of these problems. Rather, there are a variety
of useful methods of varying cost, accuracy and sophistication which
planners must apply in a successful assessment program.
This manual recognizes this fact by establishing a sequential assessment
approach beginning with a gross, first-cut analysis designed to determine
the relative magnitudes, and spatial and temporal distribution of major
pollution problems in an area. These analyses are intended to rely only
upon existing or readily available data bases and are designed to help
the planner avoid overly sophisticated, expensive and often unnecessary
efforts in areas where certain problems are not critical. Once the
planner has identified the critical parameters and problem areas for his
region, he may then refer to the appropriate higher order analyses which
are presented in subsequent sections of the manual.
1.4.2 Chapter Content
The content of each of the respective chapters of this manual is outlined
below:
Chapter 1 - "Introduction"
Chapter 2 - "Data Base Inventory and Preliminary Problem Identification":
indicates basic data requirements and procedures necessary for
preliminary problem identification and assessment in order to
define those additional technical steps necessary for development
of an effective areawide plan. Techniques are presented to
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assess the magnitude and impact of various classes of waste
sources, urban and non-urban, on water quality under various
seasonal and hydrologic conditions.
Chapter 3 - "Procedures for Urban Assessment of Pollutant Sources and
Loadings": provides illustrative alternative procedures
which are available to assess, in additional detail, the
magnitude of urban wastewater loads. Procedures are discussed
for definition of continuous municipal and industrial point
source loads, intermittent rainfall related combined sewer
overflows and stormwater discharges and generalized nonpoint
source urban runoff. Two alternative technical approaches
are discussed for estimation of stormwater related waste
flow and quality.
Chapter 4 - "Procedures for Non-Urban Assessment of Pollutant Sources
and Loadings": describes more detailed procedures to determine
the quantity and quality of non-urban nonpoint sources.
Methods of estimating seasonal variations in the flow and
quality of runoff originating from agricultural and forrested
areas are discussed. In addition, nonpoint source loadings
from other diverse activities including construction, residuals
disposal, mining and irrigated return flows are described.
Chapter 5 - "Analysis of Stream Impacts for Urban and Non-Urban Sources":
summarizes methods of analysis which are available to determine
the impact of urban and non-urban wastewater sources on the
quality of receiving waters. Different types of receiving
water bodies are described along with time and space scales
of water quality problems. Steady state and time varying
water quality modeling approaches are discussed as well as
single and multi-dimensional analytical networks. Data
requirements, parameter evaluation, calibration and
verification techniques are described. The use of the various
techniques is related to the urban and non-urban loading
assessment methodology discussed in Chapters 3 and 4.
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Chapter 6 - "Evaluation and Selection of Control Alternatives": a matrix
of controllable and uncontrollable sources for critical
pollutants from urban and non-urban areas is presented along
with methods of ranking structural and nonstructural
alternatives for load reduction. .Procedures to develop a
least cost mix of structural and nonstructural solutions
to meet desired water quality goals are identified.
Chapter 7 - "Examples of Assessment Methodology for Urban and Non-urban
Areas": a data base inventory and problem identification
for urban and non-urban assessments with comparative
evaluations of mass pollutant loadings and stream impacts
are provided. Additionally, a summary presentation and
selection of control alternatives is given.
1.4.3 Use and Content of Appendices
The ten appendices are intended to be supportive of the information
presented in the Chapters. However, each appendix is written for
separate identifiable subjects and may also be used independent of the
text of the manual.
The following briefly describes the content of each appendix.
Appendix A - "Model Applicability Summary": this appendix contains a summary
of computer-based mathematical tools available to areawide
water quality planners. In addition, an explanation and
data input needed for each model is presented in order to
help in the evaluation and selection of the most effective
model.
Appendix B - "Water Quality Data Bases": the availability and value of
various water quality data bases are discussed in terms of
their use in the areawide water quality planning process.
Appendix C - '.'Land Use Data Bases and Methods": a range of specific
techniques and qualitative methods for land use data
collection, management and analysis in areawide water
quality management planning is described. A descriptive survey
of alternative approaches to the land use element of the 208
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planning process, from relatively simple techniques to complex
ones, is provided.
Appendix D - "Monitoring Requirements, Methods and Costs": the best available
technical information for the design, management, and execution
of water pollution control monitoring of interest to 208
planning agencies is organized and packaged in readily useable
form. Descriptions of the manpower, equipment, and technical
methodology requirements and associated costs are also presented.
Appendix E - "Statistical .Analysis Procedures and Methods": compatible
methods for the statistical analysis of climatic data, stream
flow, pollutant accumulation and rainfall events are described.
Appendix F - "Water Quality Standards": a summary of current water quality
standards is presented along with information and problems for
interpretation and incorporation of these standards into
receiving water quality analysis.
Appendix G - "Best Management Practices": currently available performance
and cost data for urban stormwater management practices is
summarized and evaluated in light of its applicability in the
development of an areawide stormwater abatement program.
Appendix H - "Structural Cost Analysis Models and Procedures": a concise and
definitive summary of the capital and 0§M costs of all
available structural solutions to waste management problems.
This appendix also presents a step"by-step methodology for
identification, evaluation, and selection of the most cost-
effective combination of structural and non-structural control
alternatives in urban areas. This Appendix appears as Volume
III of this manual.
Appendix I - "Bibliography": an annotated bibliography of publications
frequently useful in areawide water quality management planning
is presented.
Appendix J - "Glossary of Terms": the glossary is intended to provide a
definition of technical terms used throughout the Areawide
Assessment Procedures Manual which might not be readily known
by the wide user community anticipated.
1-11
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1.5. Schedule of Mailings
The need for the Areawide Assessment Procedures Manual is an immediate
one. Because of the magnitude of the effort, it would be untimely to
withhold distribution of critical portions of the manual until the entire
document is completed. Consequently, those portions of the manual which
the Agency believes are most essential to the majority of designated
agencies at this point in the planning cycle (September 1976) will be
distributed first. Table 1-1 describes the anticipated contents and
timing of subsequent distributions aimed at completing the manual by
January 1977.
1-12
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TABLE 1-1
SCHEDULE,OF MAILINGS FOR THE
AREAWIDE ASSESSMENT PROCEDURES MANUAL
Mailing Number 1 - September 1976
Volume I: Chapter 1 - Introduction
Volume II:
Chapter 2 - Preliminary Problem Assessment
Chapter 3 - Procedures for the Assessment of Urban
Pollutant Sources and Loads
Appendix A - Model Applicability Summary
Appendix C - Land Use Data Collection and Analysis
Mailing Number 2 - December 1976
Volume I: Chapter 4 - Procedures for the Assessment of Non-Urban
Pollutant Sources and Loadings
Chapter 5 - Analysis of Receiving Water Impacts of Urban
and Non-Urban Sources
Volume II: Appendix B - Water Quality Data Bases
Appendix D - Monitoring Requirements, Methods, and Costs
Appendix E - Statistical Analysis Procedures and Methods
Appendix F - Water Quality Standards
Appendix G - Best Management Practices
Appendix I - Bibliography
Appendix J - Glossary of Terms
Mailing Number 5 - January 1977
Volume I: Chapter 6 - Evaluation and Selection of Control Alternatives
Chapter 7 - Examples of Assessment Methodology for Urban
and Non-Urban Areas
Volume II: Appendix H - Structural Cost Analysis Models and Procedures
1-13
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CHAPTER 2
PRELIMINARY PROBLEM ASSESSMENT
2.1 Introduction
In the past, many wastewater and water quality management studies have
been concerned with readily identifiable and controllable point sources
of wastewater discharge, principally of municipal and industrial origin.
The underlying assumption in many of these studies was that the most
severe water quality problems, particularly dissolved oxygen effects,
were likely to occur during relatively dry, low flow periods where
municipal and industrial treatment plant discharges would have a
predominant influence on receiving water quality. In most circumstances,
water quality effects which could not be directly related to the point
sources under study were considered as natural or background effects to
be considered as baseline water quality conditions. Wastewater management
activities were then concentrated on readily identifiable and controllable
point sources to improve water quality to the extent practical. As a
result, many of these studies resulted in the development of waste load
allocations for municipal and industrial point sources for water quality
control during periods of specified low river flow and background water
quality.
In certain cases, the results of this type of analysis are satisfactory
for effective water quality management. It is recognized, however, that
in many areas, overall long term water quality improvement requires
consideration of other factors in addition to municipal and industrial
point sources control. Even under low flow conditions, the background
water quality used as a baseline in the development of point source (
waste load allocations may be subject to improvement if the sources
which control background water quality can be identified and controlled
2-1
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in a cost-effective manner. Further, during periods of the year other
than low stream flow, water quality may be impaired by wastewater contri-
butions from a variety of sources in addition to municipal and industrial
effects. Discharges from intermittent point sources such as combined
sewer overflows, stormwater drainage, urban runoff, and numerous non-
urban non-point sources may all contribute to the degradation of a
number of water quality variables in the receiving water in differing
proportions at various times due .to the yearly hydrological cycle. The
analysis and planning problem is compounded by future development activities
which are likely to xtccur which may reduce the effect of some water
quality influences and/or intensify and redistribute others.
Under Section 208 of Public Law 92-500 support is provided for the
engineering and planning evaluation of such problems in complex urban
and" industrial settings. The principal purpose of 208 studies is the
local development of cost-effective areawide wastewater management plans
for initial and longer term water quality control in a framework suitable
for modification in a continuing planning process. A broad scale of
water quality control options are to be considered with specific evaluation
. of the effects of municipal and industrial waste, combined sewer overflow
and stormwater runoff, and non-point sources from various land usage
categories. The wastewater management plan is to be cost-effective and
practical; it must focus on principal problems first, provide a procedure
to resolve remaining problems in time; and it should include non-
structural controls where possible.
In order to produce a quality plan in a complex 208 area, the array
of tasks facing the planner can be formidable. A variety of water
quality variables and goals may have to be considered throughout
a yearly cycle. Numerous point source wastewater discharges, intermittent
sources, and non-point sources may have to be assessed, in many cases
with little or no direct data. A multiplicity of techniques are available
by which to estimate intermittent and non-point source pollutional
discharges, each with specific advantages and disadvantages. Receiving
waters can differ markedly in complexity from relatively simple streams
and rivers to more complex estuaries, embayments, lakes, and coastal
2-2
-------
zones, each requiring specific methodologies for analysis. The water
quality problems may have differing time and space scales from localized
short term bacterial problems, to large spatial scale, seasonal time
scales characteristic of eutrophication of receiving waters. A wide
variety of engineering and management control options may be available
for consideration, each with unique levels of effectiveness, cost, and
operational reliability. Therefore, the immediate problem facing the
208 planner is to define the appropriate technical steps and procedures
which are to be considered in order to evaluate a multiplicity of problems
within the time and resources available and yet which will provide
adequate technical information for wastewater management planning.
The initial step in the development of a 208 water quality management
plan is associated with preliminary problem identification and assessment.
The purpose is to provide the 208 planner in the initial phase of the
project as broad a view as possible of the water quality problems, the
relative magnitude of various waste sources, and the probable impact of
the various sources on water quality. With this perspective, appropriate
technical procedures can then be selected to focus on the most important
waste sources and water quality problems, and the specific additional
data needs can be defined. The more detailed technical procedures which
are appropriate for further analysis of those waste load sources)which
are important in a planning area, are described in Chapter 3 for urban
areas, and in Chapter 4 for non-urban areas.
Chapter 2 illustrates the basic data and procedures necessary to perform
a preliminary problem assessment. The chapter will provide:
1. An identification and description of the basic data and data
sources necessary for the preliminary assessment.
2. Methods to identify and estimate the magnitude of urban and
non-urban waste sources on an annual average basis, and during
selected critical periods.
3. A method of ranking the importance of the various wastewater
sources during different points in the hydrologic cycle by an
2-3
-------
analysis of the impact on receiving water quality for a number of
key variables.
Chapter 2 is structured into several technical subsections as follows:
Water Quality Problems and Standards *• The definition of various water
quality problems which may be encountered in local areas and common
characteristics of water quality standards which will be relevant.
Characteristics of the Planning Area *• A description of the fundamental
information necessary for preliminary problem assessment including
quantification of point source waste discharges, land use categorization,
hydrology and receiving water characteristics.
Water Quality Data Base - A description of the types and sources of water
quality data which may be useful to identify water quality problems and
determine waste load impacts.
Waste Source Identification and Evaluation - A discussion of the procedures
to define or estimate the magnitude of various waste sources including
continuous municipal and industrial point sources, intermittent
urban loadings from combined sewer overflows and storm drainage,
and non-urban non-point source for a variety of land uses.
Receiving Water Analysis - The categories and a discussion of various
types of receiving waters including streams and rivers, estuaries,
coastal embayments, and lakes and the general characteristics of
mathematical water quality modeling techniques useful for determination
of water quality impacts.
Illustration and Interpretation of Impact Analysis - A presentation of a
simplified technique, by use of an example, to illustrate how existing
or potential water quality problems can be identified in streams or
rivers and how various waste sources can be ranked in order of importance
for specific periods in the hydrologic cycle by determination of water
quality impact. The guidance is presented for the proper interpretation
of the results of preliminary problem '
2-4
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assessments so that appropriate methodologies and procedures can be
selected for inclusion in the detailed work plan.
Much of the data and procedures discussed in Chapter 2 are of a general
character and will be applicable to many local problem settings.
However, in order to further explain the utility of this information, an
example problem is included in several of the subsections to illustrate
the practical application for a particular problem setting. The "importance
of this sample problem should not be minimized. It is designed both to
instruct and to illustrate the preliminary assessment methodology in
sufficient detail to enable the reader to perform the analysis for his
specific problem area.
2.2 Water Quality Problems and Standards
The water quality of natural water bodies which receive waste loads from
point and non-point sources can be degraded resulting in the impairment
of beneficial uses. Point and non-point pollution can interfere with
man's uses of the water body for recreation and for water supply. In
addition, pollution can upset the natural biology of the system. In
general, problems encountered in natural water bodies can be classified
into the following major catagories: dissolved oxygen depletion; public
health risks, eutrophication, and a general category which combines
other water use interferences, including siltation and aesthetic
considerations.
2.2.1 Water Quality Problems
2.2.1.1 Dissolved Oxygen Depletion
The quantity of dissolved oxygen present provides an overall measure of
the general well-being of a receiving water. Non-polluted streams are
characterized by dissolved oxygen levels near the atmospheric saturation
concentration and exhibit healthy and diverse biological communities.
In areas of a water body adjacent to wastewater outfalls of point and non-
point waste discharges, less desirable scavanging organisms increase in
number while dissolved oxygen is reduced below saturation or may even be
2-5
-------
completely exhausted. Sedimentation of the suspended portion of the
organic matter results in bottom deposits which continue to degrade and
thereby remove dissolved oxygen from the overlying waters. Excessive
nutrient enrichment of the waters may result in the development of
substantial algal or macrophyte biomass with their associated large
diurnal fluctuations in the dissolved oxygen.
These effects of point and non-point sources combine to affect the
dissolved oxygen content of the receiving water. Thus, the dissolved
oxygen concentration of a water body is a valuable indicator of the
state of the receiving water.
2.2.1.2 Public Health
There are many aspects to the relationship between waste loads, receiving
water quality and public health considerations. For the purposes of
this assessment manual, a limited set of potential contributors to
public health problems have been considered.
The presence of infectious organisms and toxic substances creates potential
health hazards which can severely limit the intended uses of the receiving
water. Potable water supply, recreational uses and shellfish beds are
among the beneficial uses which may be affected.
Coliform bacteria are generally used as indicator organisms for the
possible presence of pathogens. Total and fecal coliform bacteria are
the most commonly used indicators. Of the two indicators, fecal coliforms
are the more reliable, since they originate in warm-blooded mammals.
While less common in data bases than total coliform counts, fecal coliform
data should be used whenever possible.
Although the presence of coliforms in receiving waters is the dominant
public health concern in the preliminary analysis, it should also be
recognized that heavy metals, pesticides and refractory materials may
enter the receiving water from municipal and industrial pollution sources
or from urban runoff. Pesticides may also originate from application to
crops in agricultural areas. These materials may accumulate to harmful
2 - 6
-------
levels in the food chain, and should be considered in the context of
areawide water quality analyses.
2.2.1.3 Eutrophication
The combination of excessive nutrients, suitable water temperature and
adequate sunlight may cause excessive production of algae and higher
plant life in natural waters. Problems associated with excessive algal
growth may include objectionable taste and odors in water supplies and
interference with water treatment operations. In addition, excessive
growth of water weeds may reduce the hydraulic capacity of natural
conduits, cause flooding of lowlands, and generally obstruct desired
uses. They may interfere with recreation by creating conditions which
interfere with the attractiveness or usefulness of a water body. As
pointed out previously, large diurnal fluctuations in dissolved oxygen
may occur as the photosynthetic or respiratory activity dominates.
2.2.1.4 Other Water Use Interferences
The more important contaminants included in this category are suspended,
floatable, and dissolved solids and solid particulates whose presence
may be harmful in themselves or serve as a transport mechanism for
sorbed pollutants. Suspended solids borne by the water may settle out
in impoundments and reduce storage capacity. Excessive levels may cause
destruction of fish life or benthic organisms. Stream flow used for
irrigation may build up high concentrations of total dissolved solids.
This results in an economic burden on downstream agricultural areas
where crop yields may be severely reduced. Finally, floatable solids
are undesirable in any natural watercourse.
In addition to the above, in some situations other parameters such as
temperature, pH, oil and grease, and specific ions in excessive concentration
sodium, chloride, etc., may also have to be considered.
For this preliminary analysis, the suspended solids are chosen since
waste source and receiving water data are generally available and the
-------
analysis framework is simple. Total dissolved solids analyses are more
complex and are treated in a subsequent chapter.
2.2.2 Water Quality Standards
Both the water quality constituents regulated by the standards and the
allowable concentration of those constituents are not the same from
state to state. In addition, some local agencies may impose water
quality regulations .which are more stringent than those imposed by the
State governments. However, the physical properties and chemical
parameters regulated by water quality standards are established for
their relationship to the well-being of the water body and the beneficial
uses which can be derived from its use.
The water quality standards are' obtained at the start of the planning
study directly from the state agencies. Usually, the state agency
publishes a document which defines the water quality criteria and
classifies each surface water body.
After the water quality classification for each water body in the 208
study area is obtained from the State, the classifications for the
particular water bodies can then be superimposed on a study area map.
For example, the 97 miles of the Black River in New York State are shown
in Figure 2-1 along with the water quality classifications. Figure 2-1
shows that the Black River and Black River Bay are divided into 6 water.
quality segments. The water quality classifications that apply to these
segments are A, C, C-trout, and D. Water usage in these stream reaches
is intended for water supply [Class A), fishing (Class C), fishing-trout
(Class C-trout), and secondary contact recreation (Class D),
Quantitative standards for these classifications are given for pH,
dissolved oxygen, dissolved solids and coliform bacteria. The standards
are listed in Table 2-1 for Class A, B, C and D waters. In addition to
the above water quality standards, New York State policy for the Lake
Ontario basin requires wastewater dischargers of 1.0 MGD or larger to
reduce effluent phosphorus to 1.0 rog/1 or less.
2-8
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> DEFERIET
to
SOURCE: (')
WATER POLLUTION INVESTIGATION!
BLACK RIVER OF NEW YORK, HYOROSCIENCE, INC.
EPA- 901/9-74-000
SCALE: MILES
•r-w^*"
02468
FIGURE 2-1
WATER QUALITY CLASSIFICATIONS OF THE BLACK RIVER
-------
NJ
I
O
TABLE 2-1
NEW YORK STATE WATER QUALITY STANDARDS
Constituent
PH
Dissolved Oxygen - mg/1
[Minimum Daily Avg)
Dissolved Solids - mg/1
Class A
6.5 - 8.5
5.0
500
Class B
6.5 - 8.5
5.0
500
Class C
6.5 - 8.5
5.0
6.0 [Trout)
500
Class D
6.0 - 9.5
Never less
than 3.0
-
[Maximum)
Total Coliform - No./lOO ml Monthly. Median Monthly Median Monthly Geom.
5,000 2,400 Mean - 10,000
Fecal Coliform - No./lOO ml Monthly Geom. Monthly Geom. Monthly Geom.
Mean - 200 Mean - 200 Mean - 2,000
Phenolic Compounds - mg/1 0.005
Source(1)
-------
The standards for dissolved oxygen and coliform bacteria presented in
Table 2-1 are for average conditions. For dissolved oxygen, the minimum
daily average is reported. For the A, B and C classifications the
specifications further stipulate that at no time shall the dissolved
oxygen concentration be less than 4.0 mg/1 for non-trout waters and no
less than 5.0 mg/1 for trout waters. In addition to specifying average
conditions, the total and fecal coliform standards also include the
minimum number of analyses required plus the maximum total coliform
counts permitted in 20 percent of the samples.
The water quality classifications and standards can also be shown on the
spatial water quality plots to assist in data interpretation. Figure 2-
2 shows the spatial dissolved oxygen data observed on August 14, 1973 in
the Black River and two of its tributaries. The dissolved oxygen standards
are shown on each of the water quality plots. The extent of the six water
quality segments and the dissolved oxygen standard for each segment can
be readily compared to the observed data in this figure. It is evident
from Figure 2-2, that during August of 1973, the dissolved oxygen
concentrations were depressed below the standards for 25 miles of the
Black River. In the two tributaries, the observed dissolved oxygen
levels were well above the dissolved oxygen standards. Similar plots
for the other water quality substances showed that acceptable levels of
the constituents were present in August.
Figure 2-3, is an example for the Jordan River in Utah, which indicates
a violation of the total coliform water quality standard. These data are
average values of all the STORET summer total coliform data. The total
coliform standard is 5,000/100 ml for the entire 52 miles of the river.
The comparison of the observed data to the total coliform standard shows
that the coliform standard is violated on an average basis for more than
30 miles of the Jordan River.
2-11
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BLACK RIVER
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12
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i
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n
FLOW AT WATERTOWN = 1 700 cfs
TEMPERATURE = I8-5°C - 26.5°C
1 _ _„ 0.0. SATURATION
I 2 M 2Q Qt
§s WATER QUALITY T °
* * 0jAriDnD~7 4
* » o 5 fi 5 • I
" _ °n° i
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P 0.0. SATURATION
2 a 5
2
WATER QUALITY
STANDARD — 7
1 1
3 /
2
(£
U
<
UJ
a
1 1 1 1 1 1 1
6,
0
MILES ABOVE MOUTH
10 8 6 4 2 0
MILES ABOVE MOUTH
{
MAXIMUM
MEAN
MINIMUM
sot/ace:
AUGUST 14, 1973
FIGURE 2-2
DISSOLVED OXYGEN DATA AND STANDARDS
(BLACK RIVER,N.Y.)
2-12
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10'
10*
LCOCHO:
T-MAXIMUM
OCEOM UEAN) OBSERVED DATA
-"-MINIMUM
—————
SOOO/IOO ml
M
\ I I
I
j I
!
i
I I f
50
40 30 20 10
DISTANCE FROM GREAT SALT LAKE-JORDAN RIVER MILES
FIGURE 2-3
INSTREAM TOTAL COLIFORM DATA
(JORDAN RIVER, UTAH)
2-13
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2.3 Characteristics of the Planning Area
2.3.1 General Description
The 208 planning area study limits are defined at the start of the
project and generally conform to political boundaries. However, in the
evaluation of all factors that affect water quality within the designated
208 planning area, it may be necessary to look beyond the political
boundaries. For example, water quality in rivers is directly related to
land use in the entire river basin which might not be entirely incorporated
within the designated 208 planning area. In estuaries, water quality at
a particular location is also affected by conditions a considerable
distance downstream because of tidally induced mixing. Therefore,
wastewater loads downstream of a 208 study area might significantly
affect upstream water quality.
In the discussions which follow, Figure 2-4 presents a map of the
hypothetical 208 planning area for the illustrative problem. The 208
study area boundary is indicated by the dashed line and the drainage
basin boundary is defined by the solid line. As shown, the section of
the South River within the 208 study area receives runoff from land
outside the 208 boundaries. At the upstream end of the study area,
near Route 80, the South River water quality is related to point and
non-point source loads that enter the river between the headwaters and
Route 80. From this example, it can be seen that the general description
of the study area should be expanded beyond the limits defined by the
designated 208 planning area. It should be emphasized that the only
purpose for expanding the extent of the original study area is to better
understand those factors that influence water quality within the original
designated 208 area.
2.3.2 Land Use
The type and quantity of non-point source loads depend on land use.
Land use can be divided into urban and non-urban areas. Generally,
the urban land uses are subdivided into residential, industrial, commercial
and open areas. The non-urban land uses are divided into areas of
2-14
-------
I
>-•
in
DRAINAGE BASIN BOUNDARY
NORTH
308 STUDY AREA BOUNDARY
SCALE:
0 I Z 3 4
MILES
LEGEND:
© — MUNICIPAL STP
H — INDUSTRIAL DISCHARGE
Q —USGS GAGE STATION
FIGURE 2-4
MAP OF HYPOTHETICAL PLANNING AREA
SOUTH RIVER>USA
-------
agriculture, forest, silviculture, mining, and feedlots. In addition,
construction and highway activities in both the urban and non-urban
areas generate non-point source (NFS) loads. Residual management practices,
such as waste disposal in sanitary landfills, may also be substantial
sources of non-point source pollution. In addition to classifying a
general land use pattern within the study area, further details concerning
land use may be required for the estimation of non-point source loads.
For example, soil type and other factors affecting erosion are used in
some empirical formulas to compute non-point source loads from open
areas. In urban areas, population density can be used in some estimating
techniques for calculating storm runoff. In addition, maps detailing
pervious and impervious areas, together with handbook relationships can
also be useful.
If land use management controls are not practiced, each land use activity
has the potential of adding to the degradation of the local and distant
waterways. In order to estimate the NFS loads for each major constituent,
it is first necessary to determine the distribution of the land use
activities in the study area and the areal extent of each land use
activity.
Land use data in any 208 study area is available from many sources.
These are described in Appendix C of this manual, Land Use Data Collection
and Analysis. In general, however, the list would include:
a. Local planning agencies
b. State planning agencies
c. Standard Metropolitan Statistical Area CSMSA) Data
d. H.U.D.
e. Previous basin plans or facilities plans
f.. Soil Conservation Service
The calculation of NFS loadings from land use activity and population
density will be discussed in more detail in Chapters 3 and 4. As a
first step in preliminary problem identification, the definition of
general land use patterns is sufficient.
2-16
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Figure 2-5 presents the general land use pattern for the hypothetical South
River 208 study area. As indicated, most of the land bordering the river is
agricultural. Forested lands are located at the northern boundary of the
drainage area and at the southeast and southwest corners. The urban areas,
Jefferson City, is located in the middle of the study area.
The drainage area distribution by land use at five points along the South
River is summarized in Table 2-2 and graphically presented in Figure 2-6.
At Milepoint 0, the Route 80 Bridge, the drainage area is 500 square miles.
For the 208 study, the land use of the upstream point and non-point source
loads is defined by water quality measurements at Milepoint 0. At Milepoint
5, the runoff from the Beaver River drainage basin (250 square miles} enters
the South River. As with the upstream drainage area, the impact of loads
within the Beaver River basin is defined from water quality measurements at
the mouth of Beaver River. The increase in drainage area between Milepoints
5 and 33 is agriculture plus forest land with 20 square miles of urban
drainage area between Milepoints 15 and 20. Since the flow in Block Creek
is minor, the drainage area of the creek is included in the analysis as part
of the NFS forest area.
The graphical presentation of the drainage area distribution clearly
demonstrates that areas outside of the 208 study area boundaries may
significantly influence water quality within the 208 study area. Most
of the drainage basin of the Beaver River and all of the upstream drainage
area are outside of the 208 study area yet they compose approximately
60% of the total drainage area at Milepoint 33. Figure 206 also graphically
shows that the urban area is a relatively small component of the total
drainage area.
An analysis of the land use similar to the above should be performed by
the 208 planning agency.
2.3.3 Hydrological Data Bases
s
The local hydrological cycle affects water quality in the drainage
basin. The runoff, which depends on the geophysical characteristics of
2-17
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-------
TABLE 2-2
DRAINAGE AREA DISTRIBUTION BY LAND USE
(SQUARE MILES)
FOR SOUTH RIVER HYPOTHETICAL EXAMPLE
Milepoint Upstream Agriculture Forest Tributary Urban
0
5
15
20
33
500
500
500
500
500
0
30
160
210
280
0
40
65
75
150
0
250
250
250
250
0
0
0
20
20
2-19
-------
1400
1200
. 1000
o
-------
the drainage basin, the land uses and control practices, and the amount,
frequency, and intensity of rainfall, may improve or degrade water
quality.
In order to assess the impact of point and NFS loads on a water body, it
is important to know the stream flow and the stream flow patterns. In
any one drainage basin, stream flow will vary over the year depending on
the rainfall and/or snowmelt. Figure 2-7 shows average monthly
distribution of runoff as percent of total runoff over the year for 16
river basins in the country. It is interesting to note that in the
Kissimmee River Basin in Florida, the stream flow is relatively constant
over the year. However, in the Yellowstone River Basin, Montana, the
maximum monthly stream flows are about 10 times as great as the minimum
monthly stream flows. In addition, the Yellowstone River has a minimum
stream flow which occurs in the month of February by contrast to the
majority of streams in the country, in which low flow occurs in late
summer or early fall.
Because of the variation in runoff across the country, it is necessary to
collect the site specific stream flow data. In general, there will be
one or more flow gaging stations within the 208 planning boundaries.
These records are published as annual surface water reports by the
U.S.G.S.. Table 2-3(a) is a sample data, sheet from the U.S.G.S. surface
water records. The data sheet summarizes drainage area, daily flows for
the year, monthly average flows, and monthly maximum and minimum flows at a
gaging station.
For the preliminary analysis, stream flow data is reduced to monthly
average flows for the number of years of record available. The annual
average stream flow is calculated in addition to the minimum average 7-
consecutive-day, one-in-ten-year low flow. All tributaries of significant
size are located with respect to the main channel. If flow information
is not available for the tributaries, then estimates of the annual
average flow and the seasonal patterns are made by assigning the same
runoff yield (cfs/sq. mile) as the major drainage basin as discussed
subsequently. After the stream flow data in the main stem and the
2-21
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to
to
Normal Distribution
of
Surface-Water Runoff
<•> OCCURS IN EACH MONTH
'6 OF THE YEAR.
FIGURE 2-7
NORMAL DISTRIBUTION OF SURFACE-WATER RUNOFF
-------
STCLUIS TRIBUTARY TO LAKE OSTAXIO
04260500 BUCK RIVER AT HATERTOWN, N.Y.
LOCATION.—Lat 43*59*08", long 75*55*30", Jefferson County, on downstream Bide of right abutaent of Vandutee Street Bridge At Vatertovn.
3.5 ol (5.6 kn) upstreaa fron Phlloael Creek.
DRAINAGE AREA.—1,876 alj (4.859 k»J).
PERIOD 07 RECORD.—July 1920 to current year.
CACE,—Uaterrstage recorder. Datum of gage U 374.88 ft (114.263 a) above scan sea level. Prior to Sept. 3, 1921, nonrecordlng gage at
sane site and datua.
AVERAGE DISCHARGE.— 54 years, 3,891 ft'/a (110.2 »V»).
EXTREMES.—Current year: Haxioiuo dlBcharge, 19,400 ftVs (549 n'/s) Mar. 8, Apr. 7; aaxiaua gag* height, 8.13 ft (2.478 •) Har. 8; mini-
nun. 116 ft'/a (3.28 n'/s) July 21 (gage height, 0.27 ft or 0.823 a); Blnlaun dally, 1,080 ft1/* (30.6 a'/s) Aug. 25.
Period of record: HaxlDua discharge, 36,700 ftVs (1,040 m>/o) Apr. 5, 1963 (gage height. 11.57 ft or 3.527 a); minimus. 10 ftVs
(0.28 m'/s) Sept. 2, 1934 (gage height, -0.19 ft or -0.058 m)j minimum dally, 137 ftVs (3.88 a'/s) Sept. 4. 1939.
Haximua discharge known, about 39,700 ft'/s (1,120 aj/s) Apr. 23, 1869 (froa New York State Huseum Bulletin 85).
REMARKS.—Records fair. Plow regulated by Stlllwater P.eservoir (sec station 04256500),' Fulton Chain of Lakes (see station 04253500), and
other reservoirs. Extensive diurnal fluctuation ac low and aedlum flow caused by ni}ls and powcrplants in and above Vatertovn. During
canal aeason, water le diverted out of basin through Porestport feeder and Black River Canal (flowing south), see station 04252000.
Uater-quallty recorda for the current year are published In Part 2 of thla report.
REVISIONS.—WSP 759: Drainage area.
DISCHARGE, IN CUBIC FEET PEP SECOND. HATEH rEAH OCTOBER 1973 TO SEPTEH8ER 1974
NOV DEC JAN FEB MAR APR MAT JUN JUL
PEAK DISCHARGE (BASE. 17,000 CF£'
DATE
12-29
3-08
TIME
2200
0430
G. H.
8.03
8.13
DISCHARGE
19,000
19,400
DATE
4-07
TIME G. H. DISCHARGE
0400 8.12 ' 19,400
SEP
1
2
3
0
S
6
7
8
9
10
11
12
13
IS
16
17
18
19
20
21
22
23
20
25
26
27
28
29
30
31
TOTAL
HEAN
HAX
HIN
CAL TS
VTR YR
1,010 2.020
1.520 3.890
l.t>20 5.310
2.200 5.490
2.320 Si 170
2.070 4,470
2.710 3.760
2.750 3.300
2.o80 3.010
2.180 2.850
1.730 2.560
1.8SO 2.480
1.850 2.530
1.930 2.580
1.990 2,530
1,880 0,360
1,950 5,770
1,860 6,150
I«o60 6,100
2,070 5,560
1,990 4,490
2,050 3.560
2,050 3,480
1,910 3.500
1,780 3>!>40
1,520 0,360
1.600 4,640
1.600 0,800
1,600 5,790
1,700 6,580
60,650 124,530
1,956 0,151
2.7SO 6,580
1.010 2.020
6.870
6.070
5.530
0.600
4.600
5.000
6.730
7,930
8,790
10.800
11,000
11,000
10,200
8,650
6,9VO
S.SIO
3,890
2,760
3.580
3,820
0.820
5.890
6,580
8,290
8,990
10.600
13,500
15.300
1 7 *bOO
1 7*600
259,010
8.355
17,600
2,780
11.900
9.840
8.160
6.930
6,200
5,580
4,780
4,470
4,490
4.450
4.510
0,620
0,300
3,700
3,170
3,420
3,700
3,760
3.480
3.320
2,890
3,120
0,450
5,600
6,050
6,250
7.050
9,380
9« 380
9 1 700
9* 770
178.540
5.759
11.900
2,890
1973 TOTAL 1.865,359 HEAN 5.111
1970 TOTAL 1.825
,850 HEAN 5,002
8.890
B.290
6 I BOO
5.790
4,780
4,490
3.7oo
3,580
3.520
3,300
3,120
3,070
3,070
3,100
3,250
2.990
2.710
2.700
2.870
2,760
3,300
3,500
6,130
6,250
6,670
'6.990
7,100
6,730
129,610
0,629
8,690
2,700
' 6.130
5.720
5.100
5.720
9.910
11.300
16,700
18,700
15,000
12,800
10,000
8.750
7.020
5.680
5.220
4.570
4.OOO
0.220
0,370
4,240
0,900
3,660
3,780
3,660
4,150
3,460
3,720
3,200
To n
0,000
207,800
6.705
18.700
3.200
HA* 18,600 MIN
HA* 20
,000 HIN
4,090
4.620
T.S20
16.700
15,700
13,900
20,000
15,600
12,600
11,200
9,030
8,250
8,890
8,000
11.700
13.700
17.200
13.900
12,000
10,000
9.070
8,530
9,380
8.600
9.800
9,000
8.610
7,580
L 1 gft
324,870
10,830
20,400
4,090
859
1,080
6.230
6.600
6.600
6.400
6.180
5.860
6.150
6,650
7,000
8,670
10,200
12.200
13.300
10,000
15,300
13.700
12.000
10,000
9.100
8,390
7,520
6,620
5.760
5.270
5.100
S.080
0.880
0.570
o , 1 30
3,880
3,780
202,000
7.806
15.300
3,780
3,600
3.500
3. bOO
3.500
3,280
3,020
2,800
2.270
2.140
2.030
3.040
0,530
4,400
3,720
3,160
3,100
3,800
4,310
3,760
3,260
2,960
2.690
2,500
2,080
2.5BO
2.530
2.500
2.800
2,530
2 , 160
92,580
3«o8c<
0,530
2,080
2.080
2.620
2.020
3.940
0,260
0,020
0,130
3,280
2,660
2,930
2,690
3,000
2.530
1.900
1.860
1.860
1.370
1.330
1.000
1,380
1.260
1,760
1,660
1.630
1.653
I. 000
1.520
1.920
2.580
3.560
0.000
75.080
2.022
0.020
1.260
0,350
3,880
2,960
2,560
3,960
5.570
5.760
5,240
0.070
2.890
2.050
.630
.920
.710
.050
.320
.3JO
.280
1.710
2.130
1.810
1,000
1,250
,180
,060
,170
.360
.210
,300
1 ,570
1 ,800
73.380
2.367
5.760
1.080
1.870
1.420
1.780
1.890
2*710
2*610
2.190
2.130
2,220
1,360
1,220
1,130
1,100
1,160
1.730
1.710
1*510
1.360
1.680
1.920
1.700
2.050
3.060
3.240
2,540
2,240
2.180
2.080
1 *890
2.080
S7.760
1.925
3.240
1.100
SOURCE: uses, SURFACE WATER RECORD,NEW YORK STATE, 1974 VOL.I
TABLE2-3(a)
SAMPLE U.S.G.S. SURFACE WATER RECORD DATA SHEET
2-23
-------
tributaries are established, these data are plotted with respect to
river miles. This information will be used in the preliminary water
quality assessment to estimate the dilution and transport of the
wastewaters which enter the stream.
For example, the hypothetical South River average monthly flows are
plotted in Figure 2-8 for gaging stations at the upstream and the
downstream end of the study area. The spatial increase in flow between
the Route 80 Bridge gage and Little Falls gage is represented by the
difference between the solid and dashed lines in the hydrograph. The
freshwater flow originating in the Beaver River drainage basin is also
shown in Figure 2-8.
The spatial distribution of the freshwater flow in the South River
drainage basin is presented in Figure 2-9 . The average annual, summer
and low flow profiles are also plotted in this figure. At Milepoints _
5 and 10, the flow is incremented by the Beaver River and Black Creek,
respectively. The linear increase in flow between Milepoints 0.0 and 33
is due to the surface and groundwater return flows along the length of
the river. The above example illustrates the presentation and reduction
of the hydrological data for 208 planning areas.
In addition to computing flow statistics and spatial flow distributions,
the total stream flow can be broken down into its components which are
the flow inputs,from groundwater, tributaries, surface returns, continuous
point sources such as wastewater treatment plants, and sewer wet and dry
weather overflows. Tributary flow data will generally be available from
the U.S.G.S. or it can be generated from local runoff rates and the
tributary drainage area as subsequently discussed. Wastewater treatment
plant flows and other continuous point sources are available from the
treatment plant records, the 201 and 303 (e) basin plans and the city
drawings. An average estimate of the groundwater input can be obtained
from the annual hydrograph. For example, Figure 2-10 shows the hydrograph
over 4 years of record for Big Cottonwood Creek in Salt Lake County, ,
Utah. On the hydrograph, the groundwater flow is estimated as the flow
occurring during periods of little rainfall or snowmelt. Tile surface
2-24
-------
I
2800
2400
2000 _
1SOO _
1200 _
800 _
400
_ SOUTH RIVER
_ YEARS OF RECORD; 1945-197
1 1
1
1 1
1
••
^
-
—
-
JAN
FEB
MAR
APR
LEGEND: FLOW-CFS
s LITTLE FALLS 12IO
r-
i 1 , 1
i i r
i i t
, , r »
r -• • • j i
1 ' j i
I ! L
MAY JUN JUL AUG SEP OCT NOV DEC
1600
1200
5
i 800
cs
i^
400
0
_ BEAVER RIVER AVO. ANNUAL FLOW-ZOO CFS
_ YEARS OFRECORD: 1952-1975
—
-
JAN
FES
MAR
APR MAY JUN JUL AUG SEP OCT NOV DEC
FIGURE 2-8
AVERAGE MONTHLY FLOW, DATA
(HYPOTHETICAL SOUTH AND BEAVER RIVER, U.S.A.)
2-- 25
-------
1600
1200 -
S
Q!
800 -
400 -
8 12 16 20 24 28 32
MILES BELOW RT. SO BRIDGE
3200
S 2400
1600
* 800
§
12
8 12 16 20 24 28
MILES BELOW RT. 8O BRIDGE
8 12 16 20 24 28 32
MILES BELOW RT. SO BRIDGE
36
. NOTE:
DATA <
AVO. A.
QUO
-
, ,
OLLECTED AT
4NUAL FLOW
,/— AVO. ANNUAL
f O O n
0°o°oo0 ° w
V
^V— LOW FLOW
1 1 1 t 1 I t
6 °o 0 UQ
o
3
1 i i t I i
i
(b)
32 36
n Or
J r 0 U
i i
y— AVO. ANNUAL _
X « «°
0 0," 0 0
-------
80.
70-
60-
u>
o 50-1
o 4O-
30-
20-
10-
-TOTAU FLOW
^—ESTIMATED GROUND
WATER FLOW
J F MAM J JA.S
1965
ONDJFUAMJJAS
1966
•OHDJFUAUJJAS
1967
ONDJ FUAMJJA
1968
WATER YEAR
SOURCE: i
FIGURE 2-10
TOTAL FLOW AND ESTIMATED GROUND WATER FLOW
BIG COTTONWOOD CREEK.UTAH
2-27
-------
runoff is the remaining unknown and it can be assigned as the difference
between the total flow and the known components.
The components of the flow at many locations in the river can be assembled
into a spatial flow distribution. In Figure 2-11, the component flows
are developed for the Jordan River during a typical summer flow period.
The flow in the Jordan River is a combination Utah Lake water, groundwater,
tributary flow, agricultural surface returns, and wastewater flow.
For some streams U.S.G.S. gaging records do not exist. In order to
determine the stream flow for a refined and definitive impact analysis,
stream flow monitoring may have to be instituted. However, crude estimates
of average stream flows can be made in order to continue the preliminary
impact analysis. Average runoff yields can be used and applied to the
specific drainage areas to estimate average stream flows. Figure 2-12(a)
shows the average annual runoff yield distribution for the entire country.
Preliminary high and low flow runoff estimates can be made with the use
of the monthly runoff distribution presented in Figure 2-7 and Figure 2-12(a)
In tidal rivers and estuaries, the freshwater flow at any location can
be estimated by adding the freshwater flows orginating from tributaries,
municipal and industrial point sources, surface inflow and groundwater
inflow. The freshwater flow in tidal rivers and estuaries produces a
freshwater velocity as it does in streams. However, the freshwater
velocity in tidal waters is generally small compared to the tidal velocity.
Tidal velocity information is available from the National Ocean Survey
which is a branch of the National Oceanic and Atmospheric Administration.
Tidal velocity information is used to calculate the atmospheric reaeration
coefficient and the average tidal translation which will be important
parts of the water quality impact analysis (Chapter 5),
2.3.4 Topography
The topography of the study area is the slope and elevation of the land.
This information is readily obtained from maps published by the U.S.G.S..
For local areas, city and state agencies can provide additional maps.
In addition to providing an overall representation of the land contours
within the study area, topographical maps may also be used to define the
2-28
-------
N)
I
N)
TRIBUTARIES
AND
DIVERSIONS
WASTE
DISCHARGES
12
o
I
800
700
600
500
O 400
U.
300
200
100
3i i "-L *
zf * -jf 5'
aT T s[ a
II -|i III* L- ol
« KO = 1- z. M
•T *T" 3TT" T" "T
Si;
IS
LEGEHOi
\ | UTAH LAKE WATER
CROUNO WATER
-I-I-) TRIBUTARIES
SURFACE RETURNS
WASTE WATER TREATMENT
PLANTS
50 40 ' 30 20
DISTANCE FROM GREAT SALT LAKE - JORDAN RIVER MILE
SOURCE: 121
FIGURE 2-11
COMPONENTS OF A TYPICAL SUMMER FLOW DISTRIBUTION
(JORDAN RIVER, UTAH)
-------
LEGEND:
RUNOFF IN
CFS/SQ. MILE
<.08
.08 to .4
.4 to .8
.8 to 1.6
1.6 to 3.1
3.1 to 6.2
R£F. U.S.DEPT. OF INTERIOR
FIGURE 2-l2(a)
ANNUAL RUNOFF YIELDS IN THE COTERMINOUS UNITED STATES
2-30
-------
drainage area of the entire river basin and also the drainage area of
major tributaries. For many rivers, the U.S.G.S. reports the drainage
area with their annual flow record publications. In the preliminary
;analysis, drainage area and runoff information can be used to estimate
river flows as discussed subsequently.
Topographic data can also provide insight into the quantity and quality
of surface runoff within the study area. Areas of high elevation generally
have more rainfall than valley regions, due to orographic effects on the
windward side'. Hence, more rainfall can be expected from mountainous
areas of the study area. Land slope also affects the relationship
between runoff and rainfall. Steeper slopes produce more runoff per
unit intensity of rainfall. Land areas with steeper slopes also have
higher erosion rates and, consequently, higher suspended solids and
associated pollutants in surface runoff. Appendix C provides a detailed
discussion of the available maps and other information.
2.3.5 Geomorphological Information
Stream channel depth and cross-sectional area data are required for the
main receiving water body. This information may be available from the
U.S.G.S., State agencies, EPA, Coast and Geodetic Survey or previous
studies. If no depth or cross-sectional area data are available, it is
usually necessary to make in-stream measurements during the 208 study.
In some study areas, time of passage (travel time) information will be
available from the U.S.G.S. or from previous studies. Time of passage
data along with stream cross-sectional area and depth data is used in
the impact analysis for computing average velocity. The time of passage
data and the channel cross-sectional area data should be related to the
stream's flow. If enough data are not available to establish these
relationships, then equations (2-1) to (2-4) can be used to estimate the
changes in river characteristics for a different flow regime. They
relate the changes in these characteristics to changes in the flow ratio
'to a power less than one:
2-31
-------
Reference: (6)
A2 ^205
^ _ r *"\ \J* -J
H2 Q2 0 4
V2 ^2 0 5
" (n2-) (2-3)
Time of Travel-
_ £
Time of Travel1
where Q is the flow rate, A is the cross-sectional area, H is the mean
stream depth, and V is the average velocity.
It should be recognized that these relationships are true only for free
flowing rivers and that the exponents may vary by 50% for any river.
Therefore, if possible, the exponents should be established from available
data. However, if there is not enough information available to establish
the exponents, then equations (2-1) to (2-4) can be used with caution.
The hypothetical South River cross-sectional area and depth data are
presented in Figures 2-9, plots (b) .and (c) . These data were collected at a
river flow approximately equal to the annual average flow. Area and
depth measurements for this flow regime are available for every mile
along the watercourse.
For ease of calculations, the river was divided into 3 areas of approximate
equal physical characteristics. Between Milepoints 0 and 5 the river
was characterized as having a cross-sectional area of 800 sq. ft. and a
depth of 3 ft. For Milepoints 5 to 20 and 20 to 33, the cross-sectional
area averaged 1,400 sq. ft. and 2,200 sq. ft. while the depth average 5
ft. and 6 ft. respectively. Equations (2-1) and (2-2) were used to
2-32
-------
determine the cross-sectional areas and depths of the three river segments
at summer flow and low flow. Table 2-3(b) summarizes the hypothetical
geometry for the South River example.
Figure 2-9, plot (d), presents the time of travel information for the South
River between the Route 80 Bridge and Little Falls. The time of passage
through the system is calculated from the freshwater flow and the
cross-sectional area in each river section: velocity = flow/cross-
sectional area and Travel Time = distance/velocity.
2.3.6 Climatological Data
Climatological data is available for many locations throughout the
country. The data is available from the National Oceanic and
Atmospheric Administration which is a section of the U.S. Department of
Commerce. Climatological data sheets contain information on air
temperature, precipitation, wind, sunshine and sky cover, visibility and
humidity. An example is shown in Figure 2-12(b). All data are daily
data except precipitation which are hourly data. Data are compiled from
records on file at the National Weather Records Center, Asheville, North
Carolina and are available from the U.S. Printing Office, Washington,
D.C. For the preliminary impact analysis, precipitation data (water
equivalents) should be reduced to average monthly and annual average
rainfall data. These data are used subsequently to provide preliminary
estimates of the combined and separate sewer overflow mass discharge
rates. Rainfall data are used in Chapters 3 and 4 to provide more
refined mass discharge estimates.
2.4 Water Quality Data Base
River water quality data are necessary for a preliminary problem
identification and also for the preliminary impact analysis. A review
of existing river water quality data might reveal existing water quality
problems. If existing water quality data are not sufficient in spatial
and temporal detail, existing water quality problems may not be obvious.
For example, dry weather water quality data does not identify the direct
impact of stormwater runoff during the storm event.
2, - 33
-------
TABLE 2-3(b)
HYPOTHETICAL SOUTH RIVER
RIVER FLOW, GEOMETRY, AND TRAVEL TIME
(AVERAGE ANNUAL, SUMMER, AND LOW FLOW)
Cross-
Milepoint Flow Condition
0-5 Avg. Annual
Summer
Low Flow
5-20 Avg. Annual
Summer
Low Flow
20-33 Avg. Annual
Summer
Low Flow .
(a)A ~0.5
JA a Q
H a Q
Cc) T ^ i +.• d-iist.
velocity
Flow
cfs
535
268
54
943
472
95
1,158
569
114
Sectional ^ J
Area
sq.ft.
800
566
253
1,400
990
443
2,200
1,555
696
dist.
Depth*- '
ft.
3.0
2.3
1.2
5.0
3.8
2.0
6.0
4.5
2.4
Travel.
days
0.46
0.65
1.45
1.39
1.97
4.40
1.56
2.20
4.93
flow/X-Sect.A
2-34
-------
I
en
I—I LOCAL CLIMATOLOGICAL DATA
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FIGURE 2-l2(b)
SAMPLE LOCAL CLIMATOLOGICAL DATA SHEET
-------
In order to establish the relationship between mass discharges and
receiving water quality, a water quality model of the receiving water is
needed. In addition, the model is used in the development of cost-
effective pollution abatement alternatives through an understanding of
the cause and effect relationship between the point and non-point source
loads and the receiving water quality. Since the reliability of water
quality models is directly dependent on the extent and reliability of
the 'water quality data that are used for calibration, a sound water
quality data base is essential for a successful 208 study.
A first step in assembling water quality data is to obtain a STORET
retrieval of water quality at stations within the general study area
limits. "STORET" is the acronym used to identify the computer oriented
U.S.E.P.A. management information system for STOrage and RETrieval of
water quality, streamflow, municipal waste facility inventory, fish
kill, and other related data (Reference: 8). Water quality data may be
.retrieved from STORET in statistically analyzed form or in raw form and
graphical displays.
The amount of data available from STORET may be quite sparse, or very
extensive. Data handling and analysis is often more effectively accomplished
if an initial step of identifying what is available is first performed. Next,
the actual data is secured and compiled in an orderly fashion. Indiscriminate
requests for data retrievals can literally inundate you with paper, and
complicate the task of organizing and evaluating it. A more effective
approach is to make a series of sequential retrievals and thus have
much of the sorting and organizing accomplished by the computer system.
Data should provide an initial sense of what is going on — the general
levels of concentration of specific parameters for comparison with
standards or objectives. Data should further indicate where things are
happening, that is where in the stream changes occur, or whether problems
tend to occur in certain locations. Since there are seasonal changes in
stream flow, temperature, rainfall, and activity (construction, irrigation,
recreation, for example) data should indicate when certain quality
levels occur or problems manifest themselves.
2-36
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To access stations and data, the analyst must know the station numbers
or follow a program which searches selected geographical areas. A
procedure is available to retrieve data for 208 areas using a keyword.
EPA is presently involved in a program which will result in the publication
of a simple STORET users manual. Generally, the 208 agencies can contact
EPA and or the states to determine the availability of STORET information
that can be retrieved. Table 2-4 lists the names, addresses and telephone
numbers of the persons to contact for information and assistance concerning
the STORET retrieval system.
Since the preliminary impact analysis is made on an average annual basis,
an EPA STORET inventory retrieval is a valuable initial data base. An
inventory provides the user with a statistical evaluation of all the
available data for each station within the geographical search limits.
A total inventory of all variables is not necessary, since many of the
parameters listed in a total inventory will be of little use in the
preliminary impact analysis. However, the water quality parameters are
obtained at all stations on the main stem of the river and at all tributary
stations.
In addition, raw data retrievals will be necessary to obtain water
quality data during times of low river flows or during the rainy seasons
if they exist. A raw data retrieval provides the user with the individual
data that went into the statistical summary of the inventory. Special
programs are available to plot stream data profiles, and to perform seasonal
analysis and regressions.
As an aid in retrieving and assembling data, Table 2-5 presents a list
of river water quality variables that' are generally useful in analyzing
dissolved oxygen, eutrophication and coliform problems. For river
dissolved oxygen analyses, the minimum data requirements are dissolved
oxygen, water temperature, and BOD . In saline waters, chloride or
O
salinity measurements are required to determine the reduction in the
dissolved oxygen saturation level associated with the salinity. It is
recommended that pH data be reviewed to identify river segments with
extreme pH values. Long-term BOD tests measure ultimate oxygen demand
which is the driving force in the oxidation of BOD. Long-term BOD tests
2-37
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TABLE 2-4
STORE! POINTS OF CONTACT
Region I
Region II
Region III
Region IV
Region V
Region VI
Region VII
Lfser Assistance
Louis Gitto
Jack Sweeney
(212) 264-4750
Ted Standish
(215) 597-8046
Point of Contact
Louis Gitto, Chief
Systems Analysis Branch
John F. Kennedy Federal Bldg.
Boston, Massachusetts 02203
Herbert Barrack, Director
Management Division
26 Federal Plaza
New York, New York 10007
(212) 264-2520
Larry Miller, Chief
Water Quality Monitoring Office
Surveillance § Analysis Division
Curtis Building
6th § Walnut Streets
Philadelphia, PA 19106
(215) 597-9823
John Marlar, Chief
Technical Support Branch
1421 Peachtree Street N.E.
Atlanta, Georgia 30309
(404) 526-3012
Christopher Timm, Director
Surveillance § Analysis Division
230 S. Dearborn Street
Chicago, Illinois 60604
(312) 353-6738
David White, Chief David White
Technical § Administration Systems Branch
1600 Patterson Street
Suite 1100
Dallas, Texas 75201
(214) 749-1176
Dan Barber
(404) 526-5989
Stu Ross
(312) 353-2061
Walter Robohn, Federal Regional
Council Representative
1735 Baltimore Avenue
Kansas City, Missouri 64108
(816) 374-5495
Dennis Degner
(816) 374-2018
758-2018
2-38
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TABLE 2-4
(Continued)
STORET POINTS OF CONTACT
Point of Contact User Assistance
Region VIII Keith Schwab, Director Tom Entzminger
Surveillance & Analysis Division (303) 837-4985
1860 Lincoln Street FTS 327-4985
Suite 900
Denver, Colorado 80203
(303) 837-4935
-Region IX Clyde Eller, Director William Lewis
Surveillance § Analysis Division (415) 556-7550
100 California Street
San Francisco, California 94111
(415) 556-7858
Region X Dr. Gary O'Neal, Director Claudia Rock
Surveillance § Analysis Division (206) 399-1580
1200 6th Avenue
Seattle, Washington 98101
2-39
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TABLE 2-5
STORET CODES FOR VARIABLES USED IN PRELIMINARY IMPACT ANALYSIS
Problem
STORET
Code No.
00300
00301
00010
00400
00525
00530
00310
00319
00320
00605
00610
00615
00620
00665
00660
31507
31509.
31515
31516
00060
Variable
Dissolved Oyxgen
Percent D.O. Saturation
Temperature
PH
SS
TDS
BOD.
3
Long -Term BOD
Long -Term BOD with
Nitrification Inhibitor
Organic Nitrogen
NH3-N (a)
N02-N
N03-N
Total Phosphorus
Ortho Phosphorus
Total Coliform
Fecal Coliform
Stream Flow^ ^
BOD-
Dissolved
Oxygen
X
X
X
-
X
X
X
X
X
X
X
Eutro-
phication
X
X
X
X
X
X
X
X
X
Public
Health Other
X
X X
X
X
X
X
X
X
X
00
Un-ionized ammonia can be computed from pH, temperature and NH_-N
If flow is retrieved, stream loadings can be calculated
2-40
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performed with and without a nitrification inhibitor measure the carbonaceous
and'total BOD respectively. The nitrogenous BOD is computed as the
total ,BOD minus the carbonaceous BOD. Organic nitrogen, ammonia, nitrite,
and nitrate serve as indicators of nitrification in a river because
organic and ammonia nitrogen are oxidized to nitrite and nitrate.
Total coliform bacteria measurements are generally sufficient to identify
contaminated sections of receiving waters. However, it is recommended
that, when available, fecal coliform data also be analyzed to further
define the fecal component of the coliform group.
Other potential water quality problems such as suspended solids, total
dissolved solids, heavy metals, toxic organic compounds and pesticides
should also be investigated by comparing existing water quality data to
standards.
State agencies are required by Section 305 of Public Law 92-500 to
conduct water quality surveys and to submit to the regional administrator
a water quality inventory describing the water quality of all navigable
waterways in ^he state on a yearly basis. Generally, the state,monitoring
programs vary from the measurement of flow and dissolved oxygen to the
collection of the parameters shown in Table 2-6. Theoretically this
data, along with U.S.G.S. data and other water quality data, is contained
in STORET. However, normal time lags and general inefficiencies may
prevent this from happening. Therefore, it is important to contact the
individual states to obtain the most recent available water quality
data. Table 2-7 lists an agency contact in each of 39 states. Additional
sources of water quality data are listed in Table 2-8.
The first priority in reviewing the STORET data retrieval, or data from
other sources, is to construct spatial water quality distributions for
various time periods. For example, a review of STORET data for ten
stations on a river might show seven of the stations were sampled on the
same day, or during the same week or month. Extracting these data and
plotting spatial distributions for as many constituents as possible is
essential since these plots provide a "picture" of river water quality
at a certain period in time.
2-41
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TABLE 2-6
WATER QUALITY PARAMETERS COMMONLY MONITORED BY STATES*
Parameter Number of States
Flow 47
Dissolved Oxygen 47
Coliform bacteria 45
Nitrogen (any form) 39
Phosphorus (any form) 35
pH 35
BOD/COD/TOC 27
Water temperature 29
Turbidity 26
Solids (any type) 27
Metals (any type) 17
Chlorides 19
Alkalinity . 15
Conductivity 16
Color 11
Sulfate 14
*0nly parameters specifically mentioned as being part of the
State's monitoring program are counted. Only parameters
listed by at least 10 States are included.
2-42
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TABLE 2-7
STATE WATER QUALITY AGENCY
Point of Contact
Alabama Ann Cummings
Water Improvement Commission
State Office Building
Montgomery, AL 36104
(205) 269-7971
Arizona Phyllis Woolscy
Water Quality Control Board
17-10 West Adams
Phoenix, AZ 85007
(602) 271-5453
Arkansas R. C. Wilson
Control and Ecology
8001 National Drive
Little Rock AR 72209
(501) 371-1701
California Phil Mendes
State Water Res. Control Board
1416 9th Street
Sacramento, CA 95814
(916) 322-2416
Colorado John Ilinton
P.O. Box 138
Delta, CO 81416
(303) 874-4411
Connecticut Charles Nula
Department of Environmental Protection
Water Compliance Unit
State Office Building (Room 126)
Hartford, CT 06115
(302) 678-4771
D.C. James Otto
Water Quality Control Division
614 I! Street N.W.
Washington, D.C. 20001
(202) 629-2538
Florida H. Duanc Mitchell
Department of Pollution Control
2562 Executive Control Circle East
Tallahassc, HL 32301
(904) 488-8626
Georgia Michael Moss
Department of Natural Resources
270 Washington Street
Room 820
Atlanta, Georgia
(404) 6SC- 4988
Idaho Gene Ralston
Department of Health and Welfare
State House
Boise, ID 83720
(208) 964-2390
Illinois Don Goodwin
Illinois Environmental Protection Agency
2200 Church Hill Road
Springfield, IL 62706
(217) 525-3362
Indiana T.P. Chang
Indiana Stream Pollution Control Board
1330 West Michigan
Indianapolis, Indiana
Point of Contact
Iowa Jim Strieker
Iowa Department of Environmental Quality
8920 Delaware Avenue *
P.O. Box 3326
DCS Moin.es, IA 50316
(SIS) 265-8134
Kansas Gerry Stoltenbcrg
State Department of Health
Water Quality and Point Source Data Division
740 Forbes AFB
Topcka, Kansas
(913) 296-3825
Kentucky Douglas C. Griffin
Division of Water Resources
Department of Natural Resources and
Environmental Protection
6th Floor-Capital Plaza Tower
Room 626
Frankfort, KY 40601
(502) 564-3980
Louisiana David Bruce
Bureau of Environmental Health
State Office Building
P.O.,Box 60630
New Orleans, LA 70160
(504) 527-5124
Maryland Wayne Overman
Tawcs State Office Building
Maryland Environmental Service
Annapolis, MD 21401
Massachusetts Russ Isaac
Massachusetts Division of Hater Control
100 Cambridge Street (Room 1901)
Boston, Mass.
(617) 727-3855
Michigan Bruce Chaffin
Michigan Water Resources Commission
Steven T. Mason Building - 8th Floor
Lansing, MI 48926
(517) 373-2867
Minnesota Bob Pope
Pollution Control Agency
1935 W. County Road
Roscvillc, MN
(612) 296-7222
Mississippi Earl Lemastcr
Mississippi Air and Water Pollution Control
P.O. Box 827
Jackson, Mississippi
(601) 354-6783
Missouri Maureen Mueller
Department of Natural Resources
Clean Water Commission
P.O. Box 176
Jefferson City, MO 6S101
(315) 751-3241
Nebraska Judy Ncwkirk
Department of Environmental Control
Lincoln, NE 68509
(402) 471-2186
2-43
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TABLE 2-7
STATE WATER QUALITY AGENCY
Point of Contact
New Jersey John Ruggcro
N. J. Dcpt. of Environmental Protection
P.O. Box 2809
Trenton, MJ
(609^ 292-7493
New Mexico Mike Snavcly
Water Quality Section
Pore Building
P.O. Box 2348
(SOS) 827-2948
New York Phil Ohy
Department of Environmental Conservation
SO Volt Road
Albany, NY
(SIS) 4S7-S73-!
North Carolina Sue Gardner
Dcpt. of National Economic Resources
P.O. Box 27687
Raleigh, NC 27611
(919) 829-4740
North Dakota Gerald Knudscn
North Dakota State Department of Health
State Capital
Bismark, NO S8S01
(701) 244-237S
Ohio Diana Rccil
Environmental Protection Agency
361 East Broad Street
Columbus, Ohio 43216
(615) 466-5760
Oklahoma Jesse Strawbridgc
Water Quality Surv.
P.O. Box S35S1
Oklahoma City, Okla.
(405) 271-5240
Oregon Van Kollias
Department of Environmental Quality
Beau-Hill
Portland, Oregon
(503) 229-5983
Point of Contact
Pennsyvania John Kitch
State of Pcnn.
Management Services Division
P.O. Box 2063
Fulton National Bldg.
3rd and Locust Streets
Harrisburg, PA 17120
(717) 787-9640
South Carolina Jay Sylvester
South Carolina Health and
Environmental Control (Room 488)
Annex 2600 Bull Street
Columbia, SC 29201
(303) 758-5165
Texas Randy Meridath
h'atcr Quality Board
P.O. Box 13246
Austin, TX
(S12) 475-S8S1
Vermont Dick Canbio
Vermont State Department of Water Resources
Water Quality Division State Office Bldg.
Montpclicr, XT 05602
(802) 828-2763
Virginia Clyde Coodin •
Virginia State Water Control Board
2111 N. Hamilton Street
P.O. Box 1143
Richmond, VA 23230
(BO'I) 770-2111
Washington Robert James
Dept. of Ecology State of Washington
7272 Clean Water Lane
P.O. Box 829
Olympia, Washington 98501
West Virginia Lcs Schnlz
Department of Natural Resources
1201 Crcnbicr Street
Charleston, West Virginia
(3u'-l) 348-2837
Wisconsin Lyman Wible
Wisconsin Dcpt. of Natural Resources
P.O. Box 450
Madison, Wisconsin S3701
(608) 266-8107
2-44
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TABLE 2-8
SUMMARY OF SOURCES OF WATER QUALITY
1, Bureau of Reclamation (Dept. of Interior)
2. U.S. Army Corps of Engineers
3. Environmental Protection Agency (Regional Offices)
4. U.S, Forest Service (Dept. of Agriculture)
5. Fish and Wildlife Service (Dept. of Interior)
6. U.S. Geological Survey (Dept. of Interior)
7. National Weather Service (Dept. of Commerce)
8. National Water Quality Surveillance System (EPA)
9. State, County and City Health Departments
10. Local University Biology, or Environmental Engineering Departments
11. Engineering Reports (such as 303-E Basin Plans and 201
Facilities Plans)
(a)
-'See Appendix D for details for water quality data sources
2-45
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Spatial water quality profiles should be developed for various river
flow and seasonal conditions. Summer low flow conditions are generally
critical with regard to dissolved oxygen. High river suspended solid
levels occur during periods of peak surface runoff. Wet weather spatial
surveys reveal stormwater runoff effects.
Water quality data with sufficient spatial detail is not likely to come
from a STORET data retrieval. Detailed spatial water quality is generally
the result of a special water quality study. In some instances the data
collected during these studies are stored in STORET. Consequently,
state governmental environmental agencies can be a source o'f extensive
river quality data that is not a part of STORET, For example Figure 2-
13, presents three spatial dissolved oxygen distributions in the Black
River, New York measured between 1969 and 1973. Plots (a), (b), and (c)
in Figure 2-13 represent data obtained from STORET, N.Y. State
Department of Environmental Conservation, and an EPA sponsored study of
the Black River respectively. A review of the STORET data does not
reveal a dissolved oxygen problem. The State data shows two river
dissolved oxygen measurements less than the standard. Finally, the data
collected during the special study provides a detailed spatial dissolved
oxygen distribution of the Black River which clearly shows a 25 mile
reach of river where the standards were not met.
Although the primary goal of a preliminary water quality inventory is to
produce spatial distributions of various constituents, it is also
advisable to isolate some temporal water quality data. Temporal dissolved
oxygen data may indicate that algal photosynthesis and respiration
significantly affect river dissolved oxygen. Data for six stations on
the Truckee River is shown in Figure 2-14. The diurnal dissolved oxygen
data for Station 4 shows that the peak afternoon dissolved oxygen
concentration of 10 mg/1 decreases to a minimum nighttime concentration
of 4 mg/1, representing a dissolved oxygen change of 6 mg/1 over the
day.
Should insufficient river water quality data exist, it is still appropriate
to proceed with the preliminary analysis in order to locate regions of
2-46
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(a)
DISSOLVED QXYGEN-(mg/l ) DISSOLVED OXYGEN -(mg /I)
i> _ O .(* » i3 5! o 4* CD N o>
j N CO XT O~"
ft/6ui)-M39j(xo 03A70SSIO
STORET DATA
SEPTEMBER 1969- MAY 1973 T
• T ,,
-------
16
12
or
STA. I
OGOO 1200 1800 2400
TIME-HR
16
8
CS
STA.2
0600 1200 1800 2400
TIME-HR
16
12
STA.3
0600 1200 1800 2400
TIME-HR
16
12
STA. 4
- • * •
0600 1200 1800 2400
TIME-HR
16
STA. 5
12
16
12
STA. 6
0600 1200 1800 2400
TIME-HR
06OO 1200 1800 2400
FIGURE 2-14
DIURNAL DISSOLVED OXYGEN VARIATIONS
(TRUCKEE RIVER,NEVADA)
2-48
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probable water quality problems. The impact analysis can be performed
using estimates and empirical relationships as discussed subsequently.
Visual observations of the study area during dry and wet weather is an
additional source of data. Field trips can provide the analyst with
increased understanding of the 208 study area and its complex problems.
Inspections provide information on the exact location of point wastewater
discharges, the location of NFS runoff inflow, areal extent of instream
weed growths, and the extent of the lateral mixing zones below wastewater
discharges or tributary inflows. In addition, field trips usually bring
the analyst in contact with local residents who prove to be invaluable
sources of qualitative data with respect to water use and misuse.
A field trip made during a storm event can provide data on the location
of stormwater overflow points. Wet weather observations also lead to
qualitative identification of instream water quality problems such as
excess suspended solids or floatables. Finally, visual inspections of
the 208 study area can pinpoint the location of NFS sediment sources.
Such sources, as abandoned open cuts or construction activity, can be
discovered on field trips.
2.5 Waste Source Identification and Evaluation
The procedures to be used for the preliminary problem assessment are
based on a mass balance analysis of the receiving water. The need for
reasonable estimates of the mass emission rates or loads is, therefore,
apparent. The characterization of the various types of discharges is
based on their origin and their variability. The minimal characterization
is an estimate of the long term average mass discharge rate, typically
in units of pounds/day. For certain classes of discharges, it may be
necessary to have an estimate of the seasonal variation of the mass
discharge rate over the year, if this variation is significant. For
preliminary analysis, a significant variation is a monthly average
variation factor of three times greater than the long term mean. This
judgement is based on the probable accuracy of the estimating procedures
used for other sources of mass for which measurements are usually not
2-49
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available. A three-fold variation appears to be the range of the
uncertainty in these estimates and this uncertainty sets the relative
accuracy of the entire analysis.
To understand this choice of criteria, it is necessary to realize that
for a given planning area the estimates recommended for use in the
preliminary assessment, in lieu of actual site-specific data, are the
averages of the long term average concentrations from the runoff of many
cities, agricultural lands, etc.. It is also necessary to consider these
data as a statistical sampling problem from a set of random variables. As
an example, for the urban combined sewer overflow concentration of
suspended solids from many cities, an estimate is needed of how far in
error the use of the mean suspended solids concentration from this set
of random variables is from the actual concentrations. A guide is that
for sets of random variables with a coefficient of variation of approximately
one, a greater than three-fold variation has a probability of less than
10%. The 10% probability appears to be a reasonable bound and is the
basis for the selection of a three-fold variation.
This probable variability sets the level of uncertainty in the overall
preliminary assessment. If the seasonal variation of a source is less
than this three-fold variation, its inclusion is not warranted since it
is a refinement above the probable level of accuracy of the overall
preliminary assessment.
2.5.1 Continuous Point Source Evaluation
Point sources effluent water quality data are available for both municipal
and industrial sources of wastewater. Other point sources of pollution
include continuous discharges from: faulty sewerage systems; inadequate
or filled interceptors; faulty regulators; exfiltration; or continuous
overflows at treatment works. It is likely that loading data will not
be available for these other point sources. However, municipal wastewater
effluent quality data can be obtained from EPA, state, and local regulatory
agencies. One of the best sources of these data are 303(e) basin and 201
facility plans. Industrial point source effluent water quality data can
be obtained from EPA, state, and local regulatory agencies and from the
2-50
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industries themselves. An additional source of effluent discharge data
for the industry of interest is the NPDES and State permits. These are
available either from the EPA region, or responsible state agency, or
the industries themselves. The Surveillance and Analysis (S£A) division
of the EPA region have measured effluent data for many industries.
Effluent water quality data exists as flow and associated concentration.
From the flow and concentration data, average annual mass discharge rates
for the continuous point sources are calculated for the variables in
Table 2-9.
TABLE 2-9
VARIABLES USED IN PRELIMINARY PROBLEM ASSESSMENT
Problem Category Variables
Dissolved Oxygen BOD,, and Total Kjeldahl
Nitrogen
Public Health Total Coliform Bacteria
Eutrophication Total Nitrogen
Total Phosphorus
Other Water Use Interferences Total Suspended Solids
For total coliforms, the average of the logarithms of the counts is used
to calculate the average. Since coliform data are generally log-
normally distributed, the arithmetic average is not a suitable measure
of the central tendency of the data.. Arithmetic averages overweight the
few very large measurements.
If adequate data is not available, municipal point source mass discharges
can be calculated based on population (see Simplified Mathematical
Modeling of Water Quality(6)) and industrial mass discharges can be
estimated from the literature based on production rates (9).
The annual average point source loads are tabulated and located with
respect to a river mileage coordinate system. Some of the sources can
be eliminated from further analysis if the loads they discharge to the
river are considered insignificant when compared to the other point
2-51
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source loads at or near that location. This may not be the case for the
analysis of projected conditions where certain sources are controllable
and others are less so.
The mass discharge rates 'for the point sources in the hypothetical South
River 208 study area are presented in Table 2-10. Loading rates are
presented for total nitrogen, total phosphorus, total suspended solids,
BOD,, and total coliform bacteria. Data are given for the upstream river
quality, the Beaver River quality, Brown Pulp and Paper (industry),
Jefferson Municipal Sewage Treatment Plant and the American Paper Company
(industry).
In Table 2-10, the nitrogen, phosphorus and coliform loading rates from
the two industries are considered insignificant and are not included in
the preliminary impact analysis. This is a judgement based on the
extremely small magnitude of the industrial loading rate when compared
the other point sources.
2.5.2 Tributary Sources
Tributaries to the main receiving water and the quality of the farthest
upstream point of the region being considered are also evaluated. These
sources are treated as continuous point sources to the main reach of the
receiving water. The evaluation of the magnitude of their contribution
is also required for the analysis. In some cases, water quality data
exists and the average concentrations can be obtained from measurements.
This is assumed to be the case for the illustrative problem. If this is
not the case, preliminary analyses of the tributary and upstream drainage
basins are required. The methods to be used are identical to those to
be presented for the main reach. The analysis is done for the portions
of the drainage area for which there are insufficient measurements.
Seasonal variations are considered if the measured concentrations show a
regular annual trend and the magnitude of the seasonal variation from the
annual mean is three-fold or greater.
The variation of concentration with river flow is also of interest.
Substances associated with point sources show a dilution effect whereas
2-52
-------
TABLE 2-10
SUMMARY OF POINT LOADS
FOR HYPOTHETICAL SOUTH RIVER EXAMPLE
Source
Upstream Q.
Beaver R.
Brown P § P
Jeff. STP
Amer. Pap.
Flow
(cfs)
500^
250^
1.6
19,8
0.8
Total
rag/1
0.2
0.5
0,
20
0
Nitrogen
Ibs/day
540 (b)
675
0
2138
. 0
Total Phosphorus
mg/1 Ibs/day
0.05 135 ^
0.10 135 ^
0 . 0
10 1069
0 0
Source
Upstream Qt
Beaver R.
Brown P § P
Jeff. STP
Amer. Pap.
Flow
Ccfs)
500^
250^
1.6
19.8
0.8
Total SS
mg/1
10
20
50
30
200
Ibs/day mg/1
27,000Cb) 1.0
27,000^ 1.5
432 50
3, 208 30
864 500
5
Ibs/day
2,700Cb)
2,025Cb)
432
, 3,208
2,160
Total Coliform
No. 100/ml No. /Day
500
1,000
0
10,000
0
6.1xl012^
6.1xl012^
0
12
4.8x10
0
(a)
(b)
Average annual flow
Loads at other flow regimes are computed proportional to flow
2-53
-------
sources associated with surface runoff and groundwater flow interact in
more complex ways. This issue is beyond the scope of a preliminary
analysis but is addressed in subsequent chapters.
2.5.3 Intermittent Urban Point Sources
The principal concern is the overflows and bypasses of the sewerage
system during rainfall events. The precise and detailed evaluation of
the mass discharges from a complex metropolitan region is a task which
can occupy the entire efforts of a planning study. It is of interest,
therefore, to estimate the importance of these mass discharges in
comparison to all other mass sources. A method is required that can
give approximate results which are suitable for comparative purposes.
Methods for estimating sewer overflow quantity and quality have been
developed in recent years. The result is a series of estimating techniques
and computer-based models which span a level of complexity from minute-
to-minute simulations that consider the detailed hydraulics and mass
transport in the urban watershed and sewerage system, to less complex
models that process hourly rainfall data and associated pollutant
concentrations in the resulting runoff. Appendix A identifies and
describes a number of such models. From the point of view .of a preliminary
analysis, it appears that many of these methods are too detailed and
cumbersome if what is required is an estimate of the significance of
urban sewer overflow relative to the other sources of mass being considered.
Examples of these methodologies are given in References 10 and 11. In
this Manual, a simple and direct method is suggested which is based on
estimating the average mass discharge rate as the product of the average
concentration in the runoff, and the average quantity of runoff. That
is, if W is the long term average mass discharge rate from an overflow
point, then
WQ = c Cy IT_A (2.5)
2-54
-------
where:
c is the average concentration (mg/1)
C is the average runoff coefficient (unitless)
IT is the average rainfall divided by the period of
averaging, T (in/hr).
A is the drainage area (acres).
This equation assumes that the random variables c, C , and I , are
uncorrelated. Recent analyses of available data (10) indicate that this
assumption is reasonable, especially if a large drainage area is served
by a single rain gage.
Treating the runoff coefficient as a random variable appears, at first
glance, to be unnecessary since, in principle, it is deterministically
related to the processes of rainfall and flow over catchments of definable
properties. However, the rainfall itself has properties which are not
definable from normally available rainfall records. The critical
element is the spatial extent of the rainfall represented by the measurement
at a point rain gage. It is this component of the actual runoff which
is behaving randomly. Therefore, it appears reasonable to treat the
overall runoff coefficient, as a random variable. An analysis of runoff
coefficients given in Figure 2-15 indicates that a relationship exists
using population density as a measure of the degree of imperviousness.
For low and medium population densities, a mean of 0.3 +_ 0.15 seems
reasonable, and results in approximately a two-fold uncertainty.
Similiar arguments can be made for treating the runoff concentration as
a random variable. Although, in principle, the mass in the runoff is
related to the accumulations of mass in the catchment and sewerage
system, it is a difficult task to formulate the relationships in a way
that is broadly applicable. All models that attempt this calculation
require extensive calibration data on a number of events in order to
give reasonable results. In lieu of such an effort, it appears justified
2 - 55
-------
1.0
0.8
•COEFFICIENT RELATED TO RESIDENTIAL AREAS ONLY
01
0\
LAND USE
AUSTIN, TEXAS
DALLAS ; RESIDENTIAL
DALLAS; R,C,I,INST. AND H'WAYS.
TULSA ; RESIDENTIAL
TULSA ; R,C,I,INST. AND H'WAYS.
MILWAUKEE
DES MOINES; RESIDENTIAL
SELBY, SAN FRANCISCO; CITY
LACUNA, SAN FRANCISCO; CITY
10,11,IS ROANOKE; RESIDENTIAL HIGH % OPEN
is DURHAM; R,C,I,INST.
14 ROSCOE ST., CHICAGO; CITY
IS CINCINNATI ; RESIDENTIAL CET.
16 MADISON,WISCONSIN; RESIDENTIAL
30
40
50
60
HIGH RESIDENTIAL
CITY
POPULATION DENSITY—PERSONS/ACRE
SOURCE: 02)
FIGURE 2-15
RUNOFF COEFFICIENT RELATED TO POPULATION DENSITY
-------
to regard the concentration as varying randomly and require only that
its statistical properties be estimated.
For the preliminary analysis the average concentration of the constituents
of interest are required. Table 2-11 summarizes the average and standard
deviation of the long term average concentrations for the parameters of
interest for selected U.S. cities. For BOD and suspended solids, the
upper 90th percentile is approximately three times the mean so that for
a given city these concentrations can be regarded as being known to
within a three-fold uncertainty.
The method is applied in the following way: available data for both
quality and quantity of urban stormwater are used if available. Site
specific data are aggregated into annual average mass discharge rates
(Ibs/day) for the preliminary analysis. If available, mass discharge
rates are tabulated for total nitrogen, total phosphorus, BOD (5 day),
total coliform bacteria and total suspended solids. In addition, the
major sewer overflow discharges are located with respect to the river
mileage coordinate system. Minor overflow discharge rates should be
combined if they are closely spaced. For example, five 0.05 MGD combined
sewer overflows within 1 mile of each other may be added together to
form a 0.25 MGD overflow at one location.
If site specific separate and combined sewer quality and quantity data
are not available, then steps 1 through 9 give a method to estimate the
mass discharge rates for the preliminary analysis.
1. Locate major overflows and determine if they are combined or
separate sewers
2. Locate and group minor overflows
3. Associate a drainage area (A) (acres) with each overflow
4. From the demographic inventory, estimate a population density
(persons/acre) for each urban drainage area. Estimate a mean
runoff coefficient C for each urban drainage area. Figure
2-15 or alternate techniques may be used.
5. Obtain the average annual rainfall from the weather bureau
2-57
-------
TABLE 2-11
SUMMARY OF STORMWATER POLLUTANT CONCENTRATIONS'
FOR SELECTED U.S. CITIEStaj
Stormwater Overflow Concentrations
00
Pollutant
BOD5
Suspended Solids
Total Coliforms
Total Nitrogen (as N)
Mean
27
608
3x10
2.
Separate Sewers
Standard
Deviation v
25 0
616 1
5
3 1.4 0
(c)
(e)
.9
.0
.6
Combined Sewers
Mean
108 .
372
6xl06
9
Standard
Deviation
36
275
-
6
(d)
(e)
v*- J
0.3
0.7
0.7
Total Phosphorus (as P) 0.5 0.4 0.8 2.8
2.9 1.0
(a)
00
Reference (12)
All units mg/1, except coliforms, MPN/100 ml
Summary of the averages of twenty cities
^ ^Summary of the averages of twenty-five cities
^v = coefficient of variation = Standard Deviation * Mean
. v describes the relative variability of the average concentration of
pollutants in runoff; as v increases, this indicates that the pollutant
concentration is becoming more variable. E.g., v > 1 highly variable,
v < 0.2 not very variable.
2-58
-------
6. Convert average annual rainfall, v, to average hourly intensity,
I,,,. I_ (inches/hour) = V (inches annual rainfall) T T (hours in
•i i i
averaging period), i.e., ! = V/T.
7. Calculate average annual runoff, Q (cfs) = I,,, (in/hr)
C A (acres).
8. Using the average concentrations given in Table 2-11 for
combined and separate sewer overflow, estimate the average
annual mass discharge rate, WQ, for each discharge. WQ (Ibs/day)
5.4 C (rog/1) QQ (cfs).
The average annual effect of the urban stormwater runoff on the water
quality of the hypothetical South River is estimated using this procedure.
The annual rainfall in the South River Basin is 40 inches/year so that
!„ = 0.00457 inches/hr. Approximately ten square miles (6400 acres) of
the total 20 square mile area of Jefferson City is sewered with combined
sewers. The remaining area is unsewered. The example further makes the
simplifying assumption that in Jefferson City there is no provision at
the municipal sewage treatment plant for the acceptance of any stormwater.
Therefore, the total untreated load flows directly to the South River.
The population density of the combined sewer area is 20 persons per
acre. From Figure 2-15 the runoff coefficient at 20 persons per acre is
C = 0.42. The average intensity and average runoff coefficient gives
an average stormwater overflow from Jefferson City of Q =12.3 cfs.
Since the combined sewers in Jefferson City are evenly spaced over the
entire 5 miles of city, the loads are expressed as Ibs. per day of a
constituent per river mile. The sewer overflows are combined with the
pollutant concentrations in Table 2-11 to yield non-point source mass
discharge rates. These rates are included in the summary table of non-
point sources in Section 2.5.2.2.
The major difficulty with a long term average analysis of transient
stormwater discharges is that the discharge occurs only during a rainfall
and this can cause water quality problems during the transient discharge.
Even if the average mass discharge rate is small, it is necessary to
perform an approximate analysis of the probable effect during such an
2-59
-------
event. Consider the impact of a continuous rainfall and runoff lasting
3 to 5 days. During this type of storm the rainfall intensity can be 5
to 10 times greater than the average annual intensity. In addition, the
base river flow can increase 2 to 5 times the average flow preceeding
the storm. This combination of rainfall and runoff can be caused by the
slowly moving frontal storms which take 3 to 5 days to pass over the
drainage basin. Although it is difficult to assess in a preliminary way
the probability of occurrence of such an event, this type of storm
provides a rough basis for analysis of a critical but not very improbable
event. An alternate possibility is a localized storm which does not
appreciably change stream flow.
For the South River Basin, rainfall records indicated that a 3^day storm
intensity of 7 times the annual average rainfall intensity is not uncommon
in the summer. In addition, the base river flow increases to 3.2 times
the annual average flow during these storms, as shown by an inspection
of the stream hydrograph. Therefore, for the preliminary impact analysis,
the storm load is assumed to be 7 times the annual average mass discharge
rate.
The seasonal variation of the average urban stormwater mass discharge is
due primarily to the seasonal variation in rainfall volume and storm
frequency. Seasonal rainfall variations can be quite substantial,
in some cases exceeding a three-fold change. Some typical seasonal
rainfall variations in intensity are illustrated in Figure 2-16.
2.5.4 Non-Point Sources (NPS)
Non-point source pollution is defined as pollution which enters a water
body from diffuse origins on the watershed and does not result from
discernible, confined or discrete conveyances. The contribution of non-
point sources can be a substantial and significant portion of the total
sources that impact the receiving waters being considered. As a consequence,
an estimate of their magnitude and receiving water impact is required
for rational preliminary analysis. The available methodology for making
quantitative estimates of the magnitude of non-point source loading
rates is analogous to that available for stormwater related urBan point
2-60
-------
.0060
.O060
-0040
.0020
OAKLAND
I I I I T*''Q^^t_^>—Ot"< [
J FMAMJJ ASON.D
MONTH
.OIOO
.0080
.0060
,.0040
.0020
BOSTON
J'FMAMJJASONO
.uia;
.0100
.0080
.0060
.O040
.O020
n
&
• TAMPA f \
\
/ \
4 \
/ ;
. /s /
V J K
»*
i i i i i i i i i i i
J'FMAMJJASONO
FIGURE 2-16
AVERAGE MONTHLY RAINFALL INTENSITY
2-61
-------
sources. Complex computer models which attempt a deterministic and
detailed calculation on short time scales are being developed But, as in
the case of the urban stormwater models, their application, if warranted,
requires extensive field data and detailed verification analysis. The
models cannot be applied without such an effort since they are not
predictive without suitable calibrations.
A class of methods being developed are based on soil erosion and sediment
transport as the principal source of the non-point source mass reaching
the receiving water. The erosion rate is computed using the Universal
Soil Loss equation which relates the sediment yield of an area to a
rainfall factor (rainfall erosion potential), soil credibility factor
(topographic slope and steepness factor), cropping management factor
(related to extent of vegetation cover), and erosion control practice
factor. The ratio of sediment generated in the region of analysis to
that reaching the receiving water is used to account for the sediment
transport. In order to compute the mass discharge rate of nutrients and
BOD, it is further assumed that these constituents are a fixed multiple
of the sediment mass reaching the receiving water. Since several of
these factors can be uncertain up to an order of magnitude, the estimate
of sediment loading to the receiving water can have a substantial uncertainty
associated with it. A more detailed exposition and evaluation of this
method is contained in Chapter 4.
Therefore, the method that is recommended for the preliminary analysis
is, as in the case of the stormwater evaluation, a simple estimate based
on the average annual yields of drainage basins of various categories.
For the purposes of the preliminary analysis, sources of non-point loads
are separated into the following land use types: agriculture, feed-
lots, forest, and non-sewered urban. The choice of the long term scale
(annual) and large spatial scale (drainage basin wide) is consistent
with the temporal and spatial scale of the preliminary impact analysis.
Although seasonal effects are addressed in an approximate way, the
uncertainty of the annual estimates may exceed the variations due to
seasonal effects.
2-62
-------
The available literature on non-point source nutrient yield, which are
presented in units of pounds/square mile/day, are based on yearly
averages reported in the literature. A wide variability in the data is
encountered within specific land use patterns. Significantly different
nutrient loads are also observed according to the monitoring procedures
used to obtain the data. Therefore, the data are chosen in terms of the
spatial and temporal scales appropriate for the application. Non-point
source load estimates are segregated according to the three basic
monitoring procedures generally used to obtain the data. These three
procedures are:
1. Seepage Study - These include lysimeter studies and sampling of
tile drainage effluent. The water being analyzed has percolated
through the soil profile and, thus, may contain significant quantities
of leached nutrients.
2. Runoff Study - These studies typically involve very small tracts of
land devoted to a single and specific land use. Samples are collected
only during runoff events. Water sampled in these studies includes
significant quantities of particulate matter with which most of the
nutrients are associated.
3. Drainage Area Study - These studies involve continuously flowing
streams which drain a particular land type. Flow is usually monitored
continuously and samples are periodically collected for nutrient
analysis.
Only the results of drainage area study are used for the preliminary
analysis since the spatial scale is most appropriate. In addition, it
is quite difficult to translate small temporal and spatial scale mass
loadings to the quantity which eventually enters the receiving water.
For example, if agricultural lands are considered, a large range in
yield is possible for both total and inorganic nitrogen and phosphorus
depending on the spatial scale to which the data apply. Table 2-12
presents a summary of available data for the three spatial scales.
Seepage and runoff studies exhibit a range of at least two orders of
magnitude for all nutrient forms reported. The range in the results of
2-63
-------
TABLE 2-12
AGRICULTURAL NUTRIENT YIELDS, POUNDS/SQUARE MILE/DAY
1. Seepage Studies - Tile Drainage or Lysimeter Studies
_ Nitrogen Yield _ _ Phosphorus Yield
(SL) fal
Number^ J Mean Range Number^ J Mean Range
Total 15 44.0 0.5-172. 9 1.82 0.08-12.1
Inorganic 28 30.4 0.5-128. 6 0.83 0.02- 3.9
2. Runoff Studies- Surface Runoff From Small Test Plots
_ Nitrogen Yield _ Phosphorus Yield _
Number^ * Mean Range Number^ * Mean Range
Total 25 48.2 1.41-414. 16 9.23 0.17-47.0
Inorganic 14 1.23 0.02-7.2 -
5. Drainage Area Studies - Stream Sampling
Nitrogen Yield _ Phosphorus Yield _
Number ^ Mean Range Number ^ Mean Range
Total 23 15. 1.9 -58.0 35 0.73 0.05-3.9
Inorganic 17 12. 1.72-32.8 9 0.23 0.05-0.91
4. Comparison of Mean Yields
Nitrogen _ Phosphorus
Total Inorganic Total Inorganic
Seepage Studies 44 30.4 1.82 0.83
Runoff Studies 48 1.2 9.23
Drainage Area 15 12. 0.73 0.23
Indicates number of studies .
Source: Reference (13)
2-64
-------
drainage area studies is somewhat smaller, especially for total nitrogen
where the minimum and maximum value differ by about an order of magnitude.
As shown at the bottom of Table 2-12, the different monitoring procedures
yield significantly different results. The seepage studies indicate
very high nitrogen yields with a high percentage of inorganic or soluble
nitrogen being leached from the soil. Similarly, runoff studies indicate
similarly high yields for total nitrogen; however,. most of this is in
the particulate form. Phosphorus yields are higher in the runoff studies
than in seepage studies, reflecting the ability of many soils to retain
this element. Nutrient yields reported from drainage area studies are
significantly lower than seepage or runoff studies. Furthermore, the
nitrogen measured in drainage area studies is predominantly in the
inorganic form. Apparently, much of the particulate matter observed in
runoff events from small plots of land is not transported to perennial
stream channels.
Thus, drainage area studies appear to have the widest and most direct
application for estimation of nutrient loads to receiving waters.
Runoff studies would have application in evaluation of the impact of
specific land management practices, e.g., plowing techniques, crop
rotations, and fertilizer applications. However, these runoff studies
would have to be conducted in conjunction with drainage area studies, in
order to quantitatively establish the link between the two. The physical
transport and the chemical mechanisms involved in this link may be quite
complex, and a substantial technical and financial commitment would be
required to establish, calibrate, and verify a quantitative framework
for the analysis.
A summary of the drainage basin yields for the various categories of
land use are shown in Table 2-13. This table is used for the preliminary
assessment of non-point source loading.
Seasonal variations of non-point source loads can be substantial,
particularly if the sources are from agricultural lands. It is likely
that the variability of the seasonal distribution is a cause of the
2-65
-------
TABLE 2-13
RUNOFF AREAL LOADING RATE - POUNDS/SQUARE MILE/DAY^
(Average Range)
Total Total
Land Use Nitrogen Phosphorus
15 1.0
(1.9-58) (0.05-3.9)
4 0.25
(1.3-16) (0.01-1.4)
8 0.5
(3.9-13.3)(0.4-1.0)
1,700 370
(1,080-2,290)(200-610)
BOD
Agriculture
Forest
Pasture
Feedlots
40
(6.3-57)
8
(6.3-11)
17
(9.4-27)
Landfill
Urban
1,250^
(50-2,500)
8
(3.3-28)
1.3
(0.4-7.9)
15,000
(80-33,100)
70
(20-129)
References 14-38
^ ^Runoff concentration in mg/1
fc")
*• J Runoff concentration in numbers/100 ml
TSS
Total
Coliform
2,500
(449-6,594)
400
(71-620)
670
(19-1,320)
3,400
1,000
(c)
(306-7,526)(1,000-24,000)
2-66
-------
variability of the estimates in Table 2-13. A method for estimating
this variability is discussed in Chapter 4.
2.5.4.1 Urban Non-Point Runoff - Application
The sources of urban runoff considered in this analysis are areas of the
city which are not sewered by either combined or separate storm sewers
and the runoff from sanitary landfill areas. .The non-sewered urban area
should be located with respect to the river and its drainage area (square
miles) determined. If mass loading rates are available from previous
studies, they are used in the impact analysis. Generally, site specific
loading rates will not be available and the literature values presented
in Table 2-13 should be used to estimate the mass loading rates for
total nitrogen, total phosphorus, BOD,., total coliform bacteria, and
D
total suspended solids.
The sewered urban area of the hypothetical example city, Jefferson City,
is 10 square miles. The non-sewered runoff loads, as calculated from the
information in Table 2-13, are presented along with the other non-point
source loads in Table 2-15. As with the combined sewer-overflows, the
non-sewered urban runoff occurs only between Milepoints 15 and 20 and is
treated as a linearly distributed mass discharge.
2.5.4.2 Rural NFS Runoff - Application
For the preliminary analysis, rural NFS runoff is assumed to originate
from forests, agricultural areas, feedlots, pastures, and undisturbed
natural areas. If site specific mass discharge rates for total nitrogen,
total phosphorus, BOD,., total coliforms, and total suspended solids are
available, they are used in the impact analysis.
If mass discharge data is not available, estimates are made based on
land use and total land area. To do this, it is necessary to sub-divide
the drainage basin into major land use types. The major land uses are
aggregated along the length of the river. For example, agricultural
areas may represent ten square miles per linear mile of river in a
certain river basin. The mass discharge rate for land uses other than
2 - 67 .
-------
the undisturbed lands is estimated using the drainage areas and the
areal loading rates shown in Table 2-13.
Background water quality concentrations are usually available for most
drainage basins. In general, background water quality is affected by
land uses and .water use practices in drainage basins upstream of 208
drainage areas. Therefore, water quality variables will be at
concentrations in excess of undisturbed background water quality. If no
data is available, background water originating from relatively undisturbed
drainage areas can be estimated using the values in Table 2-14.
The cumulative drainage area distribution associated with each land use
in the hypothetical South River drainage basin is presented in Table 2-2
and Figure 2-6. In summary, the drainage areas are: upstream, 500
square miles; tributary, 250 square miles; agriculture, 280 square
miles; forest, 150 square miles; urban, 40 square miles. In each river
reach, the change in drainage area for the agricultural areas and forest
are determined and associated with an areal loading rate from Table 2-
13. These loading rates are presented in Table 2-15 as linear mass
discharge rates (Ibs/mi/day). The upstream and tributary mass discharge
rates are assumed to be based on observed data and are not calculated
from the data in the loading Tables.
2.5.5 Summary Analysis of Mass Discharges
The results of the preliminary loading estimates for each reach of the
hypothetical South River are shown in Figure 2-17(a). The distributed
sources (Ibs/mi/day) are aggregated into the total mass discharge entering
the reach of river being considered in order that a comparison to the
point loading can be made. Such a comparison can be quite useful in
assessing the relative importance of each type of loading. However,
until some form of receiving water analysis is performed it is unclear
if these loads are producing significant water quality problems.
For the hypothetical South River, the agricultural loads for nitrogen
predominate in the upstream reaches; point and combined sewer overflow
loads predominate, in the downstream reach. The point source for phosphorus
2-68
-------
TABLE 2-14
SUMMARY OF BACKGROUND CONCENTRATIONS^ J FROM VIRGIN LAND
(a)
Parameter
Nitrogen (inorganic)
Concentration
Range
Qng/1)
Comments
0.05-0.50 highest concentrations: Iowa, Illinois,
Indiana
Phosphorus (total)
lowest concentrations: South, East West
coasts
0.0 -0.20 highest concentrations: Iowa, Nebraska,
Dakotas
BODn
Coliform (total)
(b)
Sediment (TSS)
lowest concentrations: South, East,
West coasts
0.50-3.0 highest concentrations: Iowa, Illinois
lowest concentrations: South, East
West coasts
100-2,000 highest concentrations: west of
Mississippi River
lowest concentrations: Northeast,
Southwest
2-100 highest concentrations: Montana, South
Dakota, Nebraska
lowest concentrations: East, West
coasts
(a)
(b)
See Midwest Research Institute (39) for iso-concentration maps
of virgin land runoff concentrations
Number/100 ml
2-69
-------
TABLE 2-15
SUMMARY OF NON-POINT SOURCE AND COMBINED SEWER LOADS
FOR HYPOTHETICAL SOUTH RIVER BASIN
Is)
River
Segment
(Mile-
Points^
0-5
5-15
15 - 20
20 - 33
Pollutant
Source
Agriculture
Forest
Urban Runoff
Comb. Sewer
Agriculture
Forest
Urban Runoff
Comb . Sewer
Agriculture
Forest
Urban Runoff
Comb . Sewer
Agriculture
Forest
Urban Runoff
Comb. Sewer
Total
Nitrogen-N
Ibs/mi/day
90
32
-
-
195
10
-
-
150
8
16
120
81
23
-
_
Total
Phosphorus
' Ibs/mi/day
6
2
-
-
13
0.6
-
-
10
0.5
2.6
38
5.4
1.4
-
_
TSS
Ibs/mi/day
15,000
3,200
-
-
32,500
1,000
-
-
25,000
800
6,800
4,940
13,460
2,300
-
-
BOD5
Ibs/mi/day
240
64
-
-
520
20
-
-
400
16
140
1,435
215
46
-
-
Total
Coliform
mi x 10
37
10
-
-
79
3
-
-
61
2
49
36,000
33
7
-
-
-------
I
§s
3000
2000
1000
1500
1000
500
300,000
^200,000
&> 100,000
15,000,
10,000
§* . 5,000
«a
I
A-AGRICULTURE I
F-FOREST I
B-UPSTREAM CONDITIONS
T- TRIBUTARY I
U-URBAN RUNOFF I
C-COM8INEO SEWER
P- POINT LOAD I
10
15
20
A T
BJL a
10
20
10
15
20
10
15
20
10 15
MILES BELOW RT. SO BRIDGE
20
p
|
fl
f
33
33
33
33
33
FIGURE 2-l7(a)
COMPARISON OF POINT SOURCE AND NONPOINT SOURCE
LOADS PER RIVER SEGMENT
(ANNUAL AVERAGE)
HYPOTHETICAL SOUTH RIVER EXAMPLE
2-71
-------
predominates over all other sources, whereas the agricultural source for
suspended solids predominates. Substantial quantities of BOD are derived
from agricultural, point, and combined sewer overflow, whereas combined
overflow dominates the coliform discharge by more than two orders of
magnitude.
?
It is important to realize that the estimates used in this presentation
can have a probable three-fold uncertainty due to the uncertainty in the
quantities used in the estimates. However, most conclusions reached
from an inspection of this figure are not substantially changed.
Agricultural, point and combined sewer sources contribute the majority
of the load for some or all constituents, whereas forest, upstream
inflows, and tributary sources are small in comparison.
In summary, Figure 2-17(a) allows the analyst to put in perspective the
relative importance of the point and non-point source pollutional loadings.
At this point, the analyst might make a preliminary estimate as to which
of the sources of pollution can be omitted from further analysis. What
the analysis does not illustrate is the affect that each of the loads
has on the instream water quality. Therefore, it is necessary to continue
the preliminary analysis in order to determine the impact of these loads
on receiving water quality.
2.6 Receiving Water Analysis
The analysis of the water quality of receiving waters is an integral
part of a preliminary assessment for a planning study. By establishing
the cause and effect relationship between the mass discharges and the
resulting concentrations, a rational assessment can be made of the
importance of the various sources being considered in terms of their
affect on receiving water.
From the point of view of water quality control and management, it is
desirable to examine water quality problems in terms of specific constituents,
or groups of constituents, which are discharged as a result of man's
activities and natural phenomena. One of the initial steps in the
planning effort is the identification of the water quality problems
2-72
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presently observed and those projected under future conditions of
population growth and development. Having identified the significant
present and future water quality problems, it is then necessary to
select the constituents which are discharged to the environment, from
natural and man-made activities, that are responsible for water quality
problems. It is then appropriate to consider a meaningful engineering
framework, usually a mathematical model, for analysis of the cause and
effect relationships and the methods available for improving and managing
the system. The factors which are included in the mathematical analysis
are the hydrology and the climatology of the area. From this data, the
water balances, the hydraulic circulation, the temperature structures,
the assimilation mechanisms and reactions that are involved in the
specific water quality problem are developed. Within this framework,
each specific water quality problem may be viewed from a characteristic
time and space scale which sets the degree of simplicity or complexity
of the required mathematical model.
What follows is a discussion of the general principles of water quality
analysis in receiving waters. Although the preliminary assessment
methodology is restricted to the impact on streams and rivers, the
general principles and discussions will form the basis for the subsequent
discussions in Chapter 5 that apply to more complex situations and put
into perspective the data previously assembled.
2.6.1.1 Time and Space Scales
Certain problems can be attacked relatively quickly, employing the simpler
conceptual hydraulic and quality models associated with analysis of
long-term phenomena, that is, phenomena associated with a large time
scale. The type of problem which is properly addressed in this context
is related to the long-term patterns of substances which are conservative,
such as dissolved solids or those substances which change at such slow
rates that they may be regarded as conservative.
A second scale of time which is appropriate in the investigation of
water quality problems is the annual cycle in which the time unit is a
week, month, or season. At this intermediate time scale, it may Be
2-73
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necessary to account for lateral arid vertical spatial variation in water
quality. The eutrophication problem is amenable to analysis utilizing
this intermediate time scale.
A third time scale is one in which the time unit is hours extending over
an interval of one day to possibly one week's period. This time scale
establishes a comparable spatial dimension. The spatial scale may,
therefore, involve two and possibly three dimensional analyses. Typical
problems addressed in this respect would be transient algae blooms,
unexpected spills or discharge's of pollutant mass from combined sewer
overflows.
A wide variety of planning problems can be analyzed using steady state
mathematical models which can provide the necessary spatial detail for
important water quality variables. Certain phenomena can achieve
steady state conditions within a short time interval and as such, can be
modeled with relative ease. Examples of the phenomena which can be
modeled on a steady state basis are the distribution of bacteria,
dissolved oxygen concentrations, and nutrient distributions. These
steady state representations are particularly useful because of the ease
of model operation and ability to respond rapidly and relatively
inexpensively to specific planning questions.
2.6.1.2 Hydrology and Climatology
The hydrology of the basin or metropolitan region, in particular the
freshwater flow, is of considerable importance in mathematical modeling.
This parameter determines not only the dilution which the sources of
mass receive, but also the velocity at which they move downstream. The
flow.also affects some of the reaction coefficients.
The determination of the water temperature characteristics of the river
sets the level of the reaction coefficients in any model related to
bacterial or higher order biological activity and the saturation
concentration of dissolved oxygen.
2-74
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2.6.1.3 Hydrodynamics
The hydrodynamic properties of a body of water, for example, velocity,
tidal characteristics, and turbulent diffusion, form the basic transport
mechanisms which classify the body of water into one of several generic
categories to be discussed below. The degree of detailed hydrodynamic
information that is required is strongly dependent on the time and space
scale of the problem under consideration.
River velocities can often be related to river flows by an exponential
relationship (see section 2.3.5). If information is available which
correlates velocity with flow (or depth with flow), this information can
form a basis for predicting the velocity (or depth profile) regime in a
river under different flow conditions.
Tidal velocities can often be obtained from the U.S. Coast and Geodetic
Survey Tide and Current Tables, or from direct measurement. The net
river flow in estuarine analysis also forms an important input into the
mathematical model of estuarine systems. Flow records are often available
for estuarine tributaries that would allow one to construct the net
river flow regime at the head end of an estuary and downstream along its
length. Flows due to incremental drainage area accretions can be readily
estimated with data from upstream reaches, using the approach discussed
in Section 2.3.3.
For large lakes and coastal waters, the hydrodynamic situation becomes
increasingly more complex. Density stratification further adds to the
difficulty of specifying the hydrodynamic circulation. For large and
complex circulation patterns as in lakes, the hydrodynamic equations
must be considered in determining water movements and subsequent pollutant
distributions. However, some simplified techniques are available and
are discussed in Chapter 5.<
2.6.2 Model Classification of Natural Systems
The classification of natural water systems for water quality analysis
is based primarily on the number of spatial dimensions which must be
considered and on the mixing characteristics of the body of water.,
2-75
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2.6.2.1 Streams and Rivers
The simplest situation is a one-dimensional flowing stream or river
where the mixing characteristics are such that the dispersion of the
mass of material can be neglected in comparison to the flow. In this
case, the river flow is the major mass transport mechanism. This
simplification is significant in terms of computational complexity and
the amount of information required for water quality analysis. The
fundamental equation that governs the transport of material in a non-
dispersive system for steady state and constant parameters is:
X — Vf a. * fo f^\
A dx" - "KL A (2~ ^
where:
c = concentration of substance of interest (mg/1)
t = time (days)
x = distance downstream (miles)
A = cross-sectional area (sq.ft.)
Q = river flow (cfs)
K = first-order decay coefficient (I/day)
w = distributed source of mass (Ibs/day/mile)
For a complete specification, the initial concentration, the reaction
rate, and the river flow and cross-sectional areas are required. For
some variables, there may be a coupling effect where the solution of one
equation feeds forward into a second equation and acts as-an input. For
example, the interaction between the biochemical oxygen demand and dissolved
oxygen is represented by a coupled set of equations. For more complex
reactants three, four or more equations may be required, all of which
interact through reaction kinetics.
2.6.2.2 Estuaries
An estuary is defined here as that portion of a coastal river where the
tidal action from the ocean' is a significant hydrodynamic parameter.
There are two broad sections of estuaries, the tidal river portion where
2-76
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the water body ebbs and floods but is entirely freshwater; and the lower
estuarine portion where, in addition.to the ebbing and flooding of the
tide, a significant intrusion of sea salts occurs. One or two spatial
dimensions, (e.g., the longitudinal and vertical dimensions) may be of
importance in estuaries. The primary difference between estuaries and
the one-dimensional river flow situation is the dispersive mass transport
due to the tidal mixing occasioned by tidal flow reversals. This forms
an important transport phenomena in addition to the net freshwater flow
through the estuary and, as such, must be included specifically in the
analysis.
Several methods are available to directly evaluate the dispersion
coefficient (see Chapter 5).
2.6.2.3 Lakes and Reservoirs
Lakes and reservoirs can involve either two or three spatial dimensions.
The flow regime in these bodies of water can be quite complex since
there is usually no dominant mechanisms which determines the advective
flow and mixing in contrast to the case of estuaries and rivers. The
stratification which can occur due to the absence of intense advective
or mixing forces, complicates the distribution of water quality
constituents in a vertical direction. Thus, lakes and reservoirs can
encompass a broad spectrum of complexity, ranging from completely mixed
water bodies to highly stratified water bodies.
A number of attempts have been made to define the hydrodynamic regime
associated with lakes, reservoirs and impoundments. In general, the
mixing, turbulence and advection are due to winds, seiches, and density
differences. From a practical planning standpoint, two options are open
to modeling lakes and impoundments. It may be possible to apply some of
the refined mathematical techniques which have been developed to evaluate
the hydraulic regime as discussed in Chapter 5 and Appendix A.
Alternatively, it may be possible and practical, depending on the water
quality problem being addressed, to employ observed data and field
measurements as an adequate assessment for the hydrodynamic circulations.
As an example, it is possible to obtain data on the thermal stratification
2-77
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within the lake or impoundment and accept this as the basis for
segmentation of a model of the lake. In addition, it is possible to
inject dye into various areas of the lake and determine dispersion,
mixing, and circulation patterns from an observation of the transport of
dye within the lake.
2.6.2.4 Coastal Waters
Coastal waters encompassing tidal embayments and near shore coastal
waters can require two or three-dimensional analyses. The techniques
available for evaluation of the hydraulic regime in terms of circulation
pattern, dispersional coefficients, etc., are essentially similar to
those available for evaluation of these phenomena in lakes and in
estuaries. Once again, the particular water quality problem being
addressed will dictate the most effective method of developing an adequate
understanding of the hydraulic circulation and mixing patterns.
For the preliminary impact analysis which follows, one-dimensional
streams are used for illustration purposes. Streams are discussed in
the following sections because of their ease of analysis. The calculations
for a simple stream can be performed on a desk top calculator or a slide
rule. It is understood that many of the 208 study areas include estuaries,
lakes and coastal waters. For these more complex water bodies, the
analyst will have to rely in the loading estimates and the modeling
techniques presented and discussed in Chapter 5 and Appendix A. The
solutions of the equations in estuary, lake and coastal modeling are
much more complex and generally require computer solution techniques,
2.6.3. Stream Impact Analysis
The least complex receiving water body in terms of calculating the
impact of wastewater discharges is a stream or river. The essentially
one-dimensional character of the transport, together with the
characteristically short time to reach equilibrium make possible the
simplifying assumptions of one important spatial dimension and temporal
steady state. The additional complexity of spatially varying hydraulic
and geometric characteristics are approximated by analyzing the receiving
2-78
-------
water as a sequence of segments within which it is assumed that the
hydraulic and geometric parameters are constants.
In a preliminary analysis, it is recommended that the stream be segmented
into a maximum of five reaches. The purpose of segmenting the stream
is to simplify the number of calculations required in the impact analysis
and to keep the level of detail of the impact analysis consistent with
accuracy of the load estimation. In general, stream segments are constructed
for areas of approximately constant flow, cross-sectional areas, depths,
and velocities. Additional segments are formed at the location of
important point source load inputs. If less than five stream segments
are required for the particular basin, then the analysis is more manageable.
For the hypothetical example, the South River is segmented into five
stream segments as shown in Figure 2-17(b). The reaches are between
Milepoints 0 and 5, 5 and 15, 15 and 20, 20 and 24, 24 and 33. Stream
divisions are made at Milepoints 5 and 15 for geometry and flow changes.
The divisions at Milepoint 20 and 24 are created for the municipal point
source load input and the industrial point source load input.
The average geometry is previously summarized in Table 2-3 and the
average flows are summarized in Table 2-16. In order to simplify the
equations used in the preliminary stream impact analysis which follows,
the average stream flow within the segment is used. This is an
approximation of the actual flow which increases linearly from the
beginning to the end of the stream reach. The average stream flow is
defined as the flow at the beginning of the section plus the flow at the
end of the section divided by two.
It should be noted that for the example summer storm analysis, the flow
was defined as being constant throughout the study area. This
simplification was made because of the large base flow and the variability
of the rainfall and runoff coefficient during a short duration storm.
Chapters 3 and 4 will provide details necessary to increment the stream
flow runoff during a storm event.
2-79
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BROWN PULP AND
PAPER COMPANY
JEFFERSON CITY WASTE]
TREATMENT PLANT
(AMERICAN PAPER
COMPANY
IK-
05 15 20
©
©
©
t
24 33
©
©
BEAVER
RIVER
LEGEND:
(7)-MODEL SEGMENT NUMBER
SOUTH RIVER
LITTLE
FALLS
FIGURE 2-l7(b)
MATHEMATICAL MODEL SEGMENTATION FOR
THE HYPOTHETICAL SOUTH RIVER
2-80
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TABLE 2-16
HYPOTHETICAL EXAMPLE
SUMMARY OF SOUTH RIVER FLOWS BY MODEL SEGMENT
Annual Average Summer Summer Low Summer Storm
Segment Milepoint Flow (cfs) Flow (cfs) Flow (cfs) Flow (cfs)
1
2
3
4 •
5
0
4.99
5.0
14.99
15.0
19.99
20.0
23.99
24.0
33.0
500,(535)
570
820 (903)
985
985 (1025)
1065
1065 (1088)
1110
1110(1160)
1210
25°(268)
285
41°(451)
492
492 (513)
533
^33
"(544)
555
555 (580)
605
50 (54)
57
82 (91)
99
Q9
yy(103)
107
107 (109)
111
111 (116)
121
(1625)
(1625)
(1625)
(1625)
(1625)
( ) = average flow in segment
2-81
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2.6.3.1. Method of Analysis
For the preliminary analysis, all in-stream concentrations are calculated
from equations based on the principle of conservation of mass under
steady state conditions. Critical seasonal effects are estimated by
assuming constant waste and stream characteristics for the particular
season. Concentrations will be assumed to be constant throughout the
depth and across the width of the receiving water. The receiving water
geometry is, therefore, approximated by a series of constant geometry
and constant flow segments. The governing differential equations for
the receiving water concentrations are linear so that the effects of the
individual waste sources (point, agricultural, forest, etc.) can be
calculated separately and, at a given location, added together to give
the total in-stream concentration. In summary, a spatial one-dimensional
steady state analysis is performed in order to calculate the distributions
of a receiving water constituent throughout the length of the stream in
the 208 study area. Constituents to be analyzed are grouped into three
categories: conservative, single reactant and coupled sequential reactants. •
2.6.3.2. Conservative Constituents
Conservative constituents are those that are not subject to reactive change
and remain dissolved or suspended in the stream. For the present, it is
assumed in subsequent analyses that total nitrogen, total phosphorus and total
suspended solids fall into this category on an annual average basis.
The solutions to the governing linear differential equation for both
point and distributed sources are shown in Table 2-17. Note that the
spatial coordinate x is in the direction of flow and that it is reset to
x = 0 at the upstream end of each segment. The constant Co is the in-
stream concentration at x = 0 due to waste sources entering segments of
the river upstream of the segment under consideration. It is calculated
by summing up all upstream waste inputs and dividing the sum by the flow
at x =0. Incremental increases in concentrations due to wastes entering
the segment being analyzed are evaluated by the term W/Q for the point
sources and wx/Q for the distributed sources where W is the point source
mass discharge rate (pounds/day) and w is the distributed mass discharge
2-82
-------
N)
00
Conservative
C
Reactive
L
Coupled
0
POINT SOURCE
Wl
L seqment length
i
/ .
*" £
C = C0 + W/Q
-KX/U -KX/U
-K X/U
K -K X/U
K -K X/U
+ (w/Q) • K _K [e -e
a r
NOTE,
O FLOW
X DISTANCE
C CONSERVATIVE SUBSTANCE CONCENTRATION
L REACTIVE SUBSTANCE CONCENTRATION ( BOO)
0 COUPLED SUBSTANCE CONCENTRATION (D.O. DEFICIT)
U VELOCITY
A CROSS -SECTIONAL AREA
-K X/U
-K X/U
DISTRIBUTED SOURCE
W
1 MM II M MM II
-^
C = CQ + WX/Q
-K X/U -K X/U
T T, n r I W M n r • ,
L V ' A.Kr (1 C • J
-K X/U
D = DQe a
K, -K X/U -K X/U
Q p 3T 5k .
i LO . Kr '^K"" • ie ~° J
K, K -K X/U -K X/U K - K
.w d r a ' r'^a r.
' AK ' K -K LK =
r a r a
Kr « BOD REMOVAL COEFFICIENT
Kd c BOD OXIDATION COEFFICIENT
Kg " 0,0. REAERATION COEFFICIENT
•w « NON-POINT SOURCE LOADING RATE
K '
a
TABLE 2-17
SUMMARY OF SOLUTIONS FOR POLLUTANT CONCENTRATIONS IN THE RECEIVING WATERS
-------
rate (pounds/mile/day) and x is distance (miles)., Concentrations within
the segment increase linearly due to distributed sources.
\
Since there are no removal or growth mechanisms involved, the analysis
of conservative substances reduces to a simple additive calculation of
accumulating waste loads, by source (point, agriculture, etc.) and
dividing the cumulative source total by the appropriate flow. This
procedure is illustrated in Table 2-18 for calculating total nitrogen
concentrations due to agricultural sources. Repeating this procedure
for all sources results in the estimate of the annual average
concentrations of a conservative substance in the river. The technique
for calculating the total nitrogen concentrations for all sources is
illustrated in Figure 2-18. Annual flow is.plotted. Then, cumulative
waste loadings by source are generated and receiving water concentrations
are determined as the quotient of the load and flow. For example, the
cumulative total nitrogen loading entering model segment 4 at Milepoint
20 is approximately 7,500 Ibs/day. Dividing this by the flow of 1,065
cfs and a conversion factor of 5.4 results in a concentration of 1.35
mg/1, as plotted in the Figure 2-18. Of this total, agricultural sources
contribute 0.57 mg/1 due to cumulative loads of 3,150 Ibs/day and the
effluent from the municipal sewage treatment plant (2,135 Ibs/day)
contributes 0.38 mg/1.
2.6.3.3. Reactive Constituents
Reactive constituents are subject to change within the receiving water
due to physical, chemical and biological reactions. The variables
included in the preliminary analysis framework that fall into this
category are BOD, coliform bacteria and nutrients. For reactive substances,
the critical season is usually the low flow, high temperature period of
the year. Therefore, the analysis is performed for that period. Although
total nitrogen and phosphorus are treated as conservative on an annual
average basis, they are considered reactive during the summer low flow
period due to algal uptake of the nutrients and subsequent removal by
settling.
2-84
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TABLE 2-18
HYPOTHETICAL EXAMPLE
EXAMPLE CONSERVATIVE SUBSTANCE IMPACT CALCULATION TABLE
AGRICULTURAL NON-POINT SOURCE LOADS
Total
Section
Number
1
2
3
4
5
River
Mile-
Point
0
4.99
5.0
14.99
15.0
19.99
20.00
23.99
24.0
33.0
T-NW
added
(Ibs/day)
0
450
0
1950
0
750
0
324
0
729
T-N
Cummulative
(Ibs/day)
0
450
450
2400
2400
3150
3150
3474
3474
4203
, Q^
Cummulative
(cfs)
500
570
820
985
985
1065
1065
1110
1110
1210
Nitrogen
Concentration
(mg/1)
0
0.15
0.10
0.46
0.46
0.57
0.57
0.59
0.59
0.65
(a)T-N added = T-N (Ibs/day/mi) x length(mi)
^ ^Annual average flows
2-85
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1500
10 15 2O
MfLSS BELOW RT. SO BfffDGE
SOUTH RIVER
30
33
FIGURE 2-18
INSTREAM TOTAL NITROGEN CALCULATION
{ANNUAL AVERAGE FLOW)
HYPOTHETICAL EXAMPLE
2-86
-------
Decay mechanisms occur for each of these constituents and first order
kinetics are assumed to be applicable; Representative reaction rates
for these constituents are indicated in Table 2-19. The BOD reaction
rates are particularly applicable to the carbonaceous fraction but, in
the preliminary analysis, the rate is also considered appropriate for
the nitrogenous oxygen demand. The nutrient removal rates are generally
applicable to conversion to other nutrient forms, but the lower range
also applies to estimated first order algal settling.
TABLE 2-19
RANGE OF VALUES OF REACTION COEFFICIENTS IN STREAMS
(REF. 6)
K (per day)(a)
Substance
Coliform Bacteria 1 - 3
BOD5 ' 0.2-2.0
Nutrients 0.1 - 1.0
Ca)Base e, 20°C
The coefficients in Table 2-19 are for water temperatures near 20°C.
For preliminary estimates, temperature corrections can generally be
ignored. Where appropriate conversion to other temperatures can be made
by:
Kr(T) = Kr(20)(1.047)T " 20 (2_7)
where K (T) is the reaction coefficient at temperature, T(°C), and
K (20) is the reaction coefficient at 20°C.
In this preliminary analysis, the BOD reaction coefficient (K ) accounts
o 3T
for both the oxidation and the settling of BOD . In the dissolved
O
oxygen analysis which follows, the BOD oxidation rate is assumed as
being equal to the BOD removal rate. Therefore, there is no settling
of BOD,.. An estimate of the BOD,, oxidation rate can be made using the
information in Figure 2-19(a). This Figure relates the oxidation rate
to the stream depth and is based on data collected during many stream
studies.
2 - 87
-------
4.O
O
o
O
CJ
@
I.O
O.I
0.05
-Stobl«,Rocky Bed
Moderate Treatment
Some Ammonia
Unjtoble.Sondy Channel
Highly TreaUd Effluent
with Nitrification
A
A
1.0
10.
DEPTH IN FEET
100.
LEGEND
©Shallow Streams (1-3 Ft.)
B Medium Streams (3-I5FO
A Deep Rivers (> 15 Ft)
SOURCE:
-------
Receiving water concentrations caused by point and distributed sources
are calculated from the solutions cited in Table 2-17 for reactive
substances. The form of the solution is similar to that for conservative
constituents where the first term represents the effects of upstream
loads and the second term represents the impact of point or distributed
sources entering the segment being analyzed. In the first term, the
constant L represents the residual concentration at x = 0 due to all
upstream sources and the exponential accounts for decay of L throughout
the segment being analyzed. The symbol e is the base of natural logarithms
(2.718). K is the decay rate at the summer water temperatures and U is
the average low flow water velocity in the segment (U=Q/A = average flow/
cross-sectional area). In some cases, time of travel data will be
available and should be used for the calculation of freshwater velocity.
Measured time of travel data provides the analyst with accurate stream
transport information and should be used instead of the calculated
freshwater velocity (Q/A). In this preliminary analysis, the reaction
rate for each constituent is assumed constant for all waste sources and
for all segments. Refinements to this procedure are discussed in subsequent
chapters. The second term of the reactive point source solution is
similar in behavior to the first term, with W/Q analogous to L . The •
maximum effect occurs at x = 0 and then decreases in the downstream
direction. For distributed reactive waste inputs, there is no stream
impact at x = 0 and a build-up of concentration occurs downstream, with
a maximum possible value to w/(A.K ), as x approaches infinity.
Sample calculations for five-day BOD are contained in Table 2-20 for the
summer low flow period. As indicated in the Table, the average flow,
cross-sectional area and stream velocity are first determined together
with the appropriate temperature-adjusted reaction rate. The initial
concentration due to upstream sources (L ) is then calculated from a
mass balance at x = 0. Aggregated point and distributed sources are
then entered. Substitution of the above data into the solutions presented
in Table 2-17, results in a spatial distribution of five-day BOD within
the segment being analyzed. Similar computations follow for subsequent
segments.
2-89
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TABLE 2-20
REACTIVE CONSTITUENT (BODj) SAMPLE IMPACT CALCULATION
HYPOTHETICAL EXAMPLE
TUENT (BODS) SAMPLE 1M
SUMMER LOW FLOW ANALYSIS
SEGMENT 1 - MILEPOINTS 0.0 to 5.0
Q = 268 cfs - LQ = UPSTR. BODg = 1.0 mg/1
A = 566 sq. ft. LO = (LQ) . (Qo/Qp = (1.0) . (250/268)
= 0.933mg/l
U = (Q/A) . (16.36) = 7. 75 mi/day W = 0
Kr = 0.3 Q 20°C 5 0.377/day 6 25°C w = 304 Ib/mi-day (AG + FOR)
Rewriting Equations of Table 2-17 with conversion factors for units:
-K x/U -K x/U -K x/U
L(X) = LQe r + (H/5.39Q) e r + (3.04 . w/(A.Kr)) . (1 - e r )
for x = 1 mi ,
= 0.933 e-0.377(l)/7.75 + Q + ( J()4 _ , _Q4/ (sfi6 ,_„,„ _ (1 . o-0.377(l)/7.7S,
L(l) = 0.889 + 0 + 0.201 = 1.09 mg/1
for x = 5" mi,
L(4.99) = 1.667 mg/1
SEGMENT 2 - MILErOINTS 5.0 to 15.0
Q = 4S1 cfs LQ = (1.667) . (268/451) = 0.991 mg/1
A = 990 sq. ft. W = 1444 Ib/day (trib. S indust)
U = 7.45 mi/day w = 540 Ib/rai-day (AG 6 FOR)
K = 0. 377/day
r __ __________•«— — _ ~ «— - -. .-- _ « .M. « _ _ .- _ — — — — ~- — — - — — — — • ^ — — — — — — — — — ~~
for MP 5, X . 0; L(0) - 0.991 e-0-377(0)/7.45 + (MM/(4S1) . (5.39)) -0.377(0)/7.45
* (540) . (3.04/(990x0.377))(l-e-0-377(0)/7-45))
L(0) = 0.991 + 0.594 + 0.00 = 1.59 mg/1
L(14.99) = 2.703 mg/1
Procedure repeated for segments 3, 4, and 5.
2-90
-------
The procedure is suitable for an ultimate BOD analysis (carbonaceous and
nitrogenous) as well as for coliform bacteria and summer nutrient analyses.
Relative effects of each point source and each distributed source (by
land use type) are easily determined by substitution of the single
source of interest in the appropriate segment(s). The procedure can be
tedious and use of a programmable calculator is recommended.
2.6.3.4 Sequentially Reacting Constituents
Sequential reactants occur if the growth or removal of the initial
constituent causes changes in a second constituent. For the preliminary
analysis, the initial substance being considered is ultimate oxygen
demand (UOD) and dissolved oxygen deficit is the second substance.
Thus, the removal of UOD causes an uptake of oxygen and an increase in
the DO deficit of the stream. The deficit itself is reduced through
reaeration. Stream dissolved oxygen concentrations are calculated by
deducting the DO deficits from the temperature-dependent saturation
concentration. Since saturation levels are lowest during the summer
high temperature periods, and reaction rates are highest, analyses for
dissolved oxygen will be carried out for summer low flow, drought flow
and storm flow conditions. Curves of dissolved oxygen saturation
concentrations versus temperature are shown in Figure 2-19(b).
As mentioned above, the ultimate oxygen demand from waste sources
(carbonaceous and nitrogenous BOD) will be considered as the source of
DO deficit. A single reaction rate will be used for both components and
confirmatory analyses to determine whether nitrification occurs will be
discussed in Chapter 5. For the preliminary analysis, the removal rate
of UOD (K ) will be set equal to the uptake rate of oxygen CKjl, which
assumes that settling of the BOD is insignificant, Reaeration coefficients
CK ) will be calculated from the O'Connor-Dobbins formulation (Reference
3.
40)
K =12.96 U1/2/H3/2 8 20°C
a (2-8)
2-91
-------
15.0
14.0
I
«3
I I I I I I I I I I I I I I I I I 1 I I lilt I I I I I I I I till I III
TEMPERATURE-C
FIGURE 2-19 (b)
D.O. SATURATION-TEMPERATURE-CHLORIDE RELATIONSHIP
-------
where U is the average stream velocity in ft/sec and H is the water
depth in feet. When necessary, temperature corrections can be made
using:
Ka(T) = KJ20) (1.024)T-2° (2_9)
Figure 2-20 is an alternate method useful for estimating the reaeration
coefficient where K = KT/H and K is the surface transfer rate (ft/day).
a L L
This Figure shows the range of measured values together with the curves
representing the theoretical formula.
The effect of benthal demands and the daily averaged algal effect are
not included and should be included in a more refined analysis if appropriate.
Dissolved oxygen deficits in the stream are calculated from the equations
in Table 2-17 which contain the reaction rates K , K and K, discussed
a r d
above. The symbol D represents the deficit, D is the deficit at x = 0
due to all upstream sources of UOD, and L is the residual concentration
of UOD at x = 0 due to the upstream sources. The third terms of the
equation, beginning with W/Q and w/A.K , represent the effects of the
point and distributed sources of UOD entering the segment under analysis.
Sample calculations for the dissolved oxygen analysis under summer low
flow conditions are contained in Table 2-21. For the first segment,
average geometry and flow information (Q, A, H) for the segment is
entered, and the average velocity is calculated. The assumed reaction
rate of the UOD is temperature corrected to 25°C. The reaeration rate
is then calculated for the velocity and depth of the segment and adjusted
for the temperature of 25 C. Initial deficit from upstream sources is
flow-adjusted to D = 0.93 mg/1. For carbonaceous BOD, the initial in-
stream concentration (L ) is calculated and the magnitudes of the BOD
point and distributed loads entered. Similar entries are made for the
nitrogenous BOD constituent. Note that the agricultural and forest
nitrogen loads are considered to be non-reactive since much of this
input is either ,slowly reacting or in the inorganic (nitrate) form. The
initial BOD^ concentration and loadings are then expressed as UOD by
scaling the 600^ by 1.5 (an estimate of the ratio of ultimate carbonaceous
2-93
-------
1
UJ
0.
UJ
UJ
U.
I
H-
Z
UJ
o
ti.
u.
UJ
o
o
UJ
U.
6 8 1.0
LEGEND-VELOCITY (FPS)
< 0.5
2 4 6 8 10.
DEPTH IN FEET
a loo.
A 1.0-2.5
O 2.5-3.5
S7 >3.5
SOURCE- (6)
FIGURE 2-20
TRANSFER COEFFICIENT (KL) AS A FUNCTION OF DEPTH
-------
TABLE 2-21
COUPLED (BOD - DO) SAMPLE IMPACT CALCULATION
SUMMER FLOW ANALYSIS •
HYPOTHETICAL SOUTH RIVER EXAMPLE
Q
A
H
U
K =
r
Def :
CBOD :
268 cfs
566 sq. ft.
2.3 ft.
(Q/A) . 16.
0.3 @ 20°C
Do ' "V "
Lo • ^ •
SEGMENT 1 - MUEPOINTS 0
K, =
d
K3 =
36 = 7.75 mi/day Ka =
5 0.377 ? 25°C
0,,,/Qj = (1.0) . 250/268 = 0.932 mg/1
0^/O.j = (1.0) . 250/268 = 0.932 mg/1
.0 to 5.0
Kr = 0.377 ? 25°C
12.96 u Ji(ft/sec)/H3/2(ft) 6
12. 96(0. 473^/2. 33/2) = 2.555
2.555 ( 1.02425"20) 6 25°C =
20°C
I/day
2.877 I/day
W = 0
w = 304 Ib/mi-day (AG f, FOR)
NBOD : LQ = 0
W = 0
w = 0 (AG 5 FOR assuming non-reactive)
UOD : LQ = (0.932) . 1.5 + (0) . 4.57 = 1.40 mg/1
W = 0
w = (304) . l.S + (0) . 4.57 = 456 Ib/mi-day
Rewriting equations of Table 2-17 with conversion factors for units:
-K X/U K, -K x/u -K x/U K. -K x/U -K x/U
a + L . ~~ (c r -c a ) + (K/Q . 5.39) . -- . (e -e )
D(x) = Do e . _
0 "a "r
K. K -K x/U -K x/U K - K
-4- . 3.04 . (T£ e a -e r * a v r
A.Kr
for x = 1 mi,
0.932 e-2.8(lV7.75 + ^ _0^77_ Co-0.377(1)/7.75.e-2.877(l)/7.75)
r °-377 ^ ^n4 f0-57? -2.877(1)/7.7S -0.377(l)/7.75
' 1 - J ' ' 7 c
••566 . 0.377 ' "-2.877-0.377-' ' ' V2.877
2.877 - 0.577
2.877
D(l) = 0.643 + 0.056 + 0 + .003 = 0.702 mg/1
DO = Cs - D(l) = 8.17 - 0.702 = 7.15 mg/1
D(4.99) = 0.38 mg/1
DO = 7.79 mg/1
2-95
-------
TABLE 2-21
(Continued)
COUPLED (BOD - DO) SAMPLE IMPACT CALCULATION
SUMMER FLOW ANALYSIS
SEGMENT 2 - MII.EPOINTS 5.0 - IS.O
Procedure repeated for Segment 2
D(S.OO) = 0.50 me/;
DO = 7.67 mg/1
0(14.99) = 0.92 mg/1
DO = 7.24 mg/1
Q2 = 451 cfs
L(14.99) = 2.70 mg/1
SEGMENT 3 - MILEPOIN1S 15.0 - 20.0
Q = 513 cfs
A = 990 cfs
H = 3.8 ft
U = (Q/A) . 16.35 = 8.48 mi/day
Kd = 0.3 8 20 C = 0.377 0 25 C
12.96 (.518) !V(3.8)3/2 = 1.26 8 20°C
1.40 I/day @ 2S°C
CBOD:
NBOD:
UOD:
DEF: D
upstream BOD = (2.70) . ||i = 2.97 mg/1
0
1991 Ibs/mi-day
upstream oxidizable nitrogen = 0
0
136 Ibs/mi-day
(2.37) . 1.5 = 3.56 mg/1
(1991) . 1.5 + (156) . 4.57 = 3608 Ibs/mi-day
0
CO. 92) . i= 0.31 rag/1
At siilc 15 x = 0, D
0.81
At mile 17 x = 2, D(2) = 0.31 e^'42'2''8'48 + (3.56) . ^
3608
^990 . 0.377
1.42-0.377 .
0.377
C1.42-0.377) '
D(2) = 0.59 + 0.25 + 0 + 0.11 = 0.95 mg/1
DO = 8.17 - 0.9S,= 7.22 mg/1
0(19.99) = 1.35 mg/1, D.O = 6.82 mg/1
Procedure repeated for Segment 4, and 5
(e-0.377(2)/8.48.e-] .42(21/8.48^ + „
0.377 -1.42(2)/8.48 -0.377(2)/8.48
° "C
2-96
-------
BOD to BOD ). The ratio of ultimate CBOD to BOD is not always equal to
1.5 and the ratio varies depending on the components in the wastewater.
Therefore, if a measured value is available for the different waste
loads in the-system, this ratio should be used in the preliminary input
analysis. The nitrogenous oxygen demand can be approximated by multiplying
the reduced nitrogenous constituents (organic nitrogen and ammonia) by
4.57, which is the mass of oxygen in pounds required to completely
oxidize one pound of ammonia. Total kjeldahl nitrogen measures both
ammonia-N and organic-N. The organic-N fraction is assumed to oxidize
as ammonia does.
Substitution of the above data into the equation for coupled constituents
(Table 2-17), allows calculation of dissolved oxygen deficits at any
location in segment 1. Subtraction of the deficits from the saturation
concentration of 8.17 mg/1 at 25 C (Figure 2-21) results in the predicted
dissolved oxygen concentrations. This procedure is then repeated for
downstream segments, as illustrated for segment 3 in Table 2-21.
Effects of individual waste sources on the dissolved oxygen deficit are
then determined by inputting each source into the equations and calculating
resulting deficit concentration profiles. Programmable calculators are
quite helpful to reduce the time required for these calculations.
2.7 Illustration and Interpretation of Preliminary Impact Analysis
The simple methodology presented in the impact analysis section of this
chapter is applied to total nitrogen, total phosphorus, dissolved oxygen,
total coliform bacteria and total suspended solids. Spatial distributions
of these constituents are calculated using the available data and the
cited literature estimates. Since the preliminary impact analysis is
performed using estimated loading information, it should be recognized
that the analysis is as accurate as the estimated numbers used in the
analysis. Three-fold or more changes in computed concentrations in the
receiving water can result if either significant loads or receiving
water characteristics (e.g., reaction rates) are in error. However,
this uncertainty is inherent in any preliminary assessment which relies
2-97
-------
12
10
(a)
.
I.
I,
TEMPERATURE*Z5°C
SATURATION=8.l7mg
10 15 20
MILES BELOW RT. 8O BRIDGE
25
30
CONTRIBUTIONS BY MUNICIPAL a INDUSTRIAL
CONTINUOUS SOURCES
2) CONTRIBUTIONS BY COMBINED SEWER OVERFLOWS.
CONTRIBUTIONS BY AGRICULTURAL RUNOFF.
CONTRIBUTIONS 8Y UPSTREAM AND TRIBUTARY
FLOWS AND FOREST RUNOFF.
30
MILES BELOW RT. 8O BRIDGE
SOUTH RIVZR
FIGURE 2-21
COMPUTED ESTIMATES OF DISSOLVED OXYGEN DISTRIBUTIONS
(SUMMER AVG. FLOW) AND COMPONENT D.O. DEFICIT DISTRIBUTIONS
HYPOTHETICAL EXAMPLE
2-98
-------
on average conditions and rule-of-thumb estimates. Its utility is not
diminished by these uncertainties, rather the results of the calculations
should be interpreted with the limitation clearly in mind. For each
type of analysis, a suggested set of rules is given in order to place
the calculations in proper perspective. Available water quality data
can also be used to assess the accuracy of the analysis and to correct
gross inconsistencies.
\
2.7.1 Dissolved Oxygen Analysis
2.7.1.1 Summer Average Flow
Summer is generally the critical period for stream dissolved oxygen
levels. Low river flows reduce the dilution of point and non-point
source loads and high river temperatures increase reaction rates and
reduce the dissolved oxygen saturation level thereby lessening the
assimilation capacity of the river. Impact analyses are presented for
average summer flow conditions and the minimum average 7-consecutive-day,
one-in-ten-year, low flow.
First, if there is sufficient data, the observed dissolved oxygen data is
compared with the stream standards to determine if there is a problem at
summer flows and drought flows. This preliminary comparison is performed
before the impact analysis. If the observed dissolved oxygen levels are
well above the standards Cn° violations), then the impact analysis for
dissolved oxygen is not performed. However, if the observed data is
marginal with respect to the standards or violates the standards or if
no pertinent data is available, then the impact analysis is necessary.
The interpretation of the preliminary analysis is based on an assessment
of the reliability of the calculation and is shown in Table 2-22.
2-99
-------
TABLE 2-22
DISSOLVED OXYGEN ANALYSIS
If Calculated
Dissolved Oxygen
Deficit is: Probability of a P.O. Problem
Less than 0.2 Improbable
0.2 to 2.0 ~ Possible
2.0 to 10.0 Probable
greater than 10.0 Highly Probable
For the latter categories further analysis is required.
Figure 2-21(a) shows the calculated dissolved oxygen distribution for
the hypothetical South River during the month of July 1975. The solid
line in this figure is the calculated dissolved oxygen profile. During
July 1975, the flow at the Route 80 Bridge was 250 cfs and the average
stream temperature was 25 C. The UOD oxidation rate of 0.3/day is
temperature corrected to 25°C and used along with the annual average
point and non-point source loads to calculate the dissolved oxygen
profile. Figure 2-21(b) shows the component dissolved oxygen deficit
responses to all point and non-point source -loads. The point sources
loads (municipal and industrial), the combined sewer overflows and the
agricultural runoff loads each produce about 1.0 mg/1 of dissolved
oxygen deficit between Milepoints 25 and 33. The contribution of the
upstream deficit, tributary deficit, and forest runoff at the point of
maximum deficit (Milepoints 25 to 33) is 0.25 mg/1. Based on this
analysis, the net effect of all load sources is in the order of 3 mg/1
dissolved oxygen deficit. It is, therefore, probable that a DO problem
exists in the South River. Data collection efforts and further analysis -
should be directed towards definition of the oxygen demanding materials
originating from the municipal and industrial loads, the combined sewer
overflows, and the agricultural runoff. Instream, water quality data
collection should be instituted in the region of calculated low dissolved
oxygen concentration.
2 - 100
-------
2.7.1.2 Summer Storm Flow
In the preliminary summer storm flow analysis, the combined sewer
overflows, urban runoff, and municipal waste treatment plant loads are
the major loads. Any increase in loads during storm events, such as a
change in upstream water quality and agricultural runoff, cause only
minor dissolved oxygen depressions because of the high stream flow rate.
For the hypothetical South River drainage basin, the review of the
hydrological data, as discussed in Section 2.3.3, shows the long duration
storm selected raised the stream flow by a factor of 3.2 times the
annual average flow. This results from a 3 to 5-day storm event with
rainfall of 7 times the annual average rainfall. Therefore, the annual
average combined sewer loads are increased by a factor of 7 to reflect
the increase in intensity when compared to I . The dissolved oxygen
deficit response to the combined sewer overflows, urban runoff and waste
treatment plant is presented in Figure 2-22.
The maximum deficit produced by the combined sewer overflows and urban
runoff is 3.8 mg/1 which indicates a probable problem. The combined
overflows are the largest contributors of oxygen demanding material to
the South River, therefore, additional efforts should be directed towards
the collection of site specific data and refining the loading contribution
of the combined sewer overflows during this type of storm event.
2.7.1.3 Drought Flow
The drought flow dissolved oxygen profile can be computed as well.
Since surface runoff is responsible for the transport of the non-point
source loads and since surface runoff is minor during a drought period,
only the point sources are used in the impact analysis.
For the hypothetical South River 208 study, the point source loads, both
municipal and industrial and the upstream BOD and oxygen deficit, are the only
oxygen demanding materials reaching the South River. The summer drought
flow is 50 cfs at the Rt. 80 bridge and the stream temperature is 25 C.
The deficit response (Figure 2-23(b)shows that oxidation of the UOD
2 - 101
-------
16
c»
§ 8
I4
Qo = l625cfs
TEMPERATURE =
MAX. DEFICIT.3.3 mj/l
AT rap. 38 /
10 15 20
MILES BELOW RT. 8O BRIDGE
SOUTH RIVER
25
30
LESENDi
DEFICIT DUE TO COMBINED
SEWER AND URBAN RUNOFF
DEFICIT DUE TO
0.0. DEFICIT IN S.TR EFFLUENT
FIGURE 2-22
COMPONENT D.O. DEFICIT DISTRIBUTIONS (SUMMER STORM FLOW)
HYPOTHETICAL EXAMPLE
2 - 102
-------
(a)
I"
- 10
s
2 8
2 *
{ 7day,10yrlow!low)
TEHPERATURE=2S°C
•0.0. SATURATION
•20
10
15
I
25
I
30
33
O
C
§
o
Q
Ul
O
w
5
10
MILES BELOW RT.80 BRIDGE
SOUTH RIVER
FIGURE 2-23
COMPUTED OXYGEN (DROUGHT FLOW) AND
COMPONENT D.O. DEFICIT DISTRIBUTIONS
HYPOTHETICAL EXAMPLE
2 - 103
-------
discharge from the municipal Jefferson City STP is responsible for all of the
deficit at the point of maximum deficit.
Therefore, based on a preliminary analysis, there is a probable dissolved
oxygen violation in the South River at the 7-day, 1-in-10-year low
flow.
Because of the probable problem, it is necessary to refine the analysis
to increase the confidence level. Recommended areas of refinement are
definition of the BOD reaction rate, the NBOD reaction rate, the river
geometry at low flow, the benthic oxygen demand and any photosynthetic
oxygen production or utilization. These refinements are discussed in
Chapter 5.
2.7.2 Public Health
In a preliminary impact analysis, total coliform bacteria are considered
as an indicator of the potential for health problems which arise from
direct contact with the water. Since direct human contact with water
usually occurs during the summer months, an annual average impact analysis
is improper in most areas and only summer average on storm event analyses
are performed.
For the interpretation of the results of a preliminary coliform analysis
Table 2-23 can be used for guidance. In addition, a recent study by
Johns Hopkins University (41), which relates total coliform bacteria to
water-borne disease causing organisms, may aid in the interpretation of
results.
TABLE 2-23
TOTAL COLIFORM ANALYSIS
If the Calculated Probability of
Concentration Is: a Coliform Problem
less than 100/100 ml .Improbable
less'than 1000/100 ml Possible
more than 1000/100 ml Probable
more than 10,000/100 ml Highly Probable
2-104
-------
2.7.2.1 Summer Average Flows
The hypothetical South River coliform loading data has been presented in
Table 2-15. In the impact analysis, the coliform decay rate is 1.0/day
at 20 C. Treating the coliform bacteria decay as a first order reactive
substance, using a summer average flow of 250 cfs, and the average
annual loads; the profile shown in Figure 2-24(a) is computed. As shown
in this figure, the computed profile greatly exceeds the total coliform
levels indicative of a highly probable problem. The combined
sewer overflows are indicated to exert the predominant influence on the
instream coliform concentrations. The other sources of pollution are.
calculated to contribute less than 700/100 ml of coliform bacteria. The
conclusion to be drawn from this preliminary impact analysis is that any
future efforts with respect to public health problems in the hypothetical
208 study should be directed to further quantification of the combined
sewer overflow coliform loads.
2.7.2.2 Summer Storm Flow
An estimate of the instream coliform concentrations during a typical
summer storm is presented in Figure 2-24(b) for the hypothetical example.
A typical summer storm for the South River study area is characterized
by an increase in stream flow to 3.2 times the annual average flow which
results from 2 to 5 day steady rainfall of 7 times the annual average
rainfall. As described in Section 2.5.3 the sewer overflow loading
rates increase to 7 times the annual average loading rates during this
storm period.
The instream coliform concentrations resulting from the combined sewer
overflows during the storm is the major source of coliform pollution as
is shown in this Figure. The preliminary analysis calculates instream
coliform levels to reach a maximum of 250,000/100 ml. This concentration
and the concentration for the entire river downstream of the city further
substantiates the highly probable existence of. a problem.
The direction to be followed for further coliform analysis should provide
more information on the quantity and quality of the combined sewer
2-105 .
-------
lopoopoo
Q ipoopoo
1
§ loopoo
lOpOO
lopoopoo
ipoopoo
t
loppoo
5
IOPOO
(a)
00=250 Cf»
TEMPERATURE: 35 °C
SUMMER AVERAGE CONDITIONS
10 15 20
MILES BELOW RT. 80 BRIDGE
25
30
(b)
00=I625 cf*
TEMPERATURE:25° C
SUMMER STORM CONDITIONS
10 15 20
MILES BELOW RT. SO BRIDGE
SOUTH RIVER
25
30
FIGURE 2-24
TOTAL COLIFORM DISTRIBUTIONS
(SUMMER AVERAGE FLOWS,SUMMER STORM FLOWS)
HYPOTHETICAL SOUTH RIVER EXAMPLE
2 - 106
-------
overflow. This would require that instream coliform data and combined
sewer overflow data be collected during both average conditions and
during a long duration summer storm.
2.7.3 Eutrophication
The preliminary analysis of eutrophication is based on the following
reasoning. If excessive quantities of both nitrogen and phosphorus
exist, it is likely that, given the proper environment, algae will grow.
Since the precise determination of these conditions is beyond the scope
of a preliminary analysis, it is assumed that, in the absence of any
contradictory data, conditions will be favorable for growth. Therefore,
if the concentrations of both nutrients are in excess of growth
requirements, a potential eutrophication problem exists. The
interpretation of the calculated concentration of total nitrogen CTN)>
and total phosphorus (TP) nutrients in the receiving water is shown in
Table 2-24.
TABLE 2-24
EUTROPHICATION ANALYSIS
If the Calculated
Concentration is: Probability of a Problem
TN less than 0.01 mg/1
or_ Improbable
TP less than 0.001 mg/1
TN more than 0.1 mg/1
and Potential
TP more than 0.01 mg/1
TN more than 1.0
and Probable
TP more than 0.10 mg/1
It is recognized that these concentrations are quite low and there are
situations for which these concentrations are exceeded and no substantial
biomass develops. Environmental factors, such as climate, geomorphology
of the receiving water, turbidity, etc., are as important in determining
whether a problem will develop as are the concentrations of available
2 - 107
-------
nutrients. Thus, these factors must be considered in modifying the
conclusions drawn from the preliminary analysis.
The impact analysis for total nitrogen and total phosphorus is performed
for an annual average and summer flow. For the summer or warm weather
periods when plant growth is occurring, there is uptake of the nutrients
by rooted plants or an uptake by planktonic forms which results in
removal of the total nutrients by the algal synthesis and subsequent
settling. In addition, phosphorus can be adsorbed to particles which
settle. Thus, a removal rate is specified for the summer average condition.
On an average annual basis, the nutrients that settled out during the
summer can be returned to the flow during the scouring that occurs at
high flows. If this occurs the annual average behavior is that of a
conservative substance.
2.7.3.1 Annual Average Flow
The methodology presented in Section 2.6.3 is used to calculate preliminary
nutrient concentrations in the sample drainage basin. The average
annual stream flow of 500 cfs provides dilution of the total nitrogen
and total phosphorus loads which are presented in Table 2-15. The
calculated total nitrogen profile is presented in Figure 2-25(a). The
total nitrogen concentration downstream of Milepoint 20 is 1.3 mg/1. . It
should also be noted that on a preliminary basis the municipal wastewater
treatment plant and agricultural runoff are responsible for the majority
of the nitrogen discharged to the South River.
Figure 2-25(b) presents the calculated total phosphorus profile. The
municipal wastewater discharge provides about 70% of the instream phosphorus.
2.7.3.2 Summer Average Flow
Total nutrients are estimated by assuming nutrient removal is occurring
during the algal growth period. For a preliminary analysis, total nutrients
are removed at a rate of O.I/day. When the dilution (upstream) flow is
reduced to 250 cfs, and the point and NFS loading rates remain the same,
the profiles presented in Figure 2-26 are computed. In general, the
2-108
-------
0.35
10
15 20
MILES BELOW RT.8O BRIDGE
SOUTH RIVER
25
30
33
FIGURE 2-25
TOTAL NUTRIENT DISTRIBUTIONS
(ANNUAL AVERAGE FLOW)
HYPOTHETICAL EXAMPLE
2 - 109
-------
s
^_^ (o)
Q0=250cfs
LEGEND:
©-CONTRIBUTIONS BY MUNICIPAL STP.
©-CONTRIBUTIONS BY AGRICULTURAL RUNOFF
©-CONTRIBUTIONS 3Y ALL OTHER SOURCES.
©
to 15 I ao
MILES BELOW RT.8O BRIDGE
25
30
[^CONTRIBUTIONS BY MUNICIPAL STf.
©-CONTRIBUTIONS BY AGRICULTURAL RUNOFF.
CONTRIBUTIONS BY ALL OTHER SOURCES.
10 15 | 20
MILES BELOW RT BO BRIDGE
SOUTH RIVER
FIGURE 2-2G
TOTAL NUTRIENT DISTRIBUTIONS
(SUMMER AVERAGE FLOW)
HYPOTHETICAL EXAMPLE
2 - 110
-------
stream concentrations of total nutrients approximately double. Also,
as shown for the annual average flow, the agricultural NFS nitrogen and
municipal nitrogen loads are responsible for the majority of the calculated
instream nitrogen. The municipal wastewater treatment plant effluent
contributes by far the majority, of the phosphorus to the South River.
Based on a preliminary analysis, the potential for a eutrophication
problem is indicated for the South River. Nutrient concentrations are
greatly in excess of that required for substantial algal biomass.
However, two factors may mitigate against its development. The travel
time through the stream is ten days or less • (Figure 2-9) and relatively
high suspended solids concentration are calculated in Section 2.7.4,.
which would limit light penetration. Hence, it is clear that further
analysis is necessary before a definitive assessment can be made.
. 2.7.4 Other Water Quality Interferences '
The other water quality interferences can be caused by substances that
are either conservative, reactive or sequentially reactive. For example
purposes, total suspended solids are evaluated for the hypothetical
South River 208 study. For an approximate analysis, the total suspended
solids are considered to be conservative.
The interpretation of total suspended solids concentrations, TSS, are
tentatively based on the levels indicated in Table 2-25.
TABLE 2-25
TOTAL SUSPENDED SOLIDS
If Calculated Concentration is: Probability of a Problem
Less than 10 mg/1 Improbable
Less than 100 mg/1 Potential
More than 100 mg/1 Probable
2 - 111
-------
2.7.4.1 Annual Average Flow
The estimated TSS NFS loads and known point source loads previously
discussed are used as the input data for the impact analysis. The
calculated instream TSS concentrations are shown in Figure 2-27(a) using
the annual average stream flow for dilution of the loads. The computed
unit responses for each land use show the agricultural NFS TSS loads
account for over 90% of the instream suspended solids.
2.7.4.2 Summer Storm Flow
As discussed in Section 2.5.3, a summer storm in the sample South River
Basin has been defined as having 7 times the average annual rainfall
intensity over a 2 to 5 day period. This increased rainfall results in
an increase in the stream flow to 3.2 times the average flow. During
this type of storm, the impact of urban sources are evaluated. The
calculated total suspended solids profile for these conditions is presented
in Figure 2-27(b).
Total suspended solids increase over existing conditions is 50 mg/1.
Therefore, the urban point and intermittent point sources create a
potential total suspended solids problem in the South River during a
long duration summer storm. Hence, a more detailed analysis is required
together with a data gathering program.
2.7.5 Summary of Results of the Impact Analysis
The preliminary assessment of the hypothetical South River planning area
indicates that problems in all the categories analyzed are either probable
or highly probable. However, the causes of these problems have been
restricted to only certain of the sources of mass within the drainage
area. Table 2-26 presents the results in a compact form. It is clear
from this compilation that agriculture, and point sources are each
important in assessing dissolved oxygen and eutrophication problems.
Further, coliforms are dominated by urban combined sewers while suspended
solids are dominated by agriculture and urban combined sewers.
2 - 112
-------
150
(a)
200
150
50
(b)
Q0=l625cfs
I
URBAN SOURCES ONLY
COMBINED SEWERS +
URBAN RUNOFF + S.T. P.
y URBAN RUNOFF + S.T.P.
10 15 20
MILES BELOW RT. 80 BRIDGE
SOUTH RIVER
25
30
33
FIGURE 2-27
TOTAL SUSPENDED SOLIDS DISTRIBUTIONS
(ANNUAL AVERAGE FLOW, SUMMER STORM FLOW)
HYPOTHETICAL EXAMPLE
2 - 113
-------
TABLE 2-26
SIGNIFICANT SOURCES OF SOUTH RIVER POTENTIAL WATER QUALITY PROBLEMS
(HYPOTHETICAL EXAMPLE)
Sources
to
l
Agriculture
Forest
Upstream conditions
Tributaries
Urban NFS
Urban combined sewers
Point Sources
Dissolved Oxygen
significant contributor to
probable problem at summer
flow
Public Health
Eutrophication
Suspended Solids
significant contributor to predominate contributor to
public porblem at annual and potential problem at annual
summer flow and summer flow
Not likely to be a significant contributor to any of the listed problems
Further analysis required
Further analysis required
Not likely to be a significant contributor to any of the listed problems
significant contributor to
p.obablc problem at summer flow
and predominate contributor at
stormflow
Significant contributor to
piobable problem at summer flow
and predominate contributor at
drought flow
Predominate contributor to Further analysis required
a highly probable problem
at summer and storm flow
Significant contributor to
probable problem at annual
and summer flow
Predominate contributor to
probable problem at storm
flow
-------
Two sources, the runoff from the forested areas and urban runoff from
non-sewered areas, can be eliminated from further considerations.
In summary, the preliminary impact analysis methodology and the load
estimate generation procedure presented previously is given as a suggested
procedure. It is realized that there are and will be some areas of the
technique which are subject to question. However, the procedure presented
can, in many cases, put a proper perspective on the problem. The preliminary
analysis might identify specific areas for additional analysis or it
might identify areas which warrant additional data collection. In some
instances the analysis will account for the total extent of the mathematical
modeling analysis which is needed for the 208 project.
If pollution sources, such as combined sewer overflows, are identified
as being responsible for affecting water quality then further analysis
might be in order. Chapter 3 and Chapter 4 can aid the analyst in a
proper direction to take for the additional analysis. If the water body .
is more complicated than a stream, then both the preliminary data collection
and the load generation should help the analyst put a better perspective
on the sources of pollution. In addition, Chapter 5 will help by introducing
higher level modeling techniques which are available for water quality
impact analyses.
2.8 References
1. Hydroscience, Water Pollution Investigations: Black River of New York,
Environmental Protection Agency, Publication EPA-905/9-74-009
(December 1974).
2. Hydroscience, Salt Lake County 208 Project (In Progress)
3. Geraghty, Miller, Var Der Leeden, Troise, Water Atlas of the United
States, A Water Information Center Publication (1973).
4. United States Geological Survey, Surface Water Records of New York
State, (1971).
2 - 115
-------
5. Hely, Mower, Harr, Water Resources of Salt Lake County3 Utah, State
of Utah, Department of Natural Resource, Tech. Pub. No. 31 (1971).
6. Hydroscience, Simplified Mathematical Modeling of Water Quality,
Environmental Protection Agency Publication (March 1971).
7. Environmental Science Services Administration, Local Climatological
Data3 Salt Lake City3 Utah (January 1971), United States Department
of Commerce.
8. Training Manual, Storage and Retrieval of Water Quality Data,
Environmental Protection Agency Publication.
9. Eckenfelder, Water Quality Engineering for Practicing Engineers3
Barnes and Noble Publishers.
10. Heaney, Huber, Mix (University of Florida), Stormwater Management
Model, Level I, Preliminary Screening Procedures, Environmental
Protection Agency Publication.
11. Lager, Didriksson, Otte, (Metcalf and Eddy, Inc.), Development and
Application of a Simplified Stormwater Management Model, Environmental
Protection Agency Publication.
12. Hydroscience, Storm Water Management Model (In Progress).
13. .Hydroscience, Methodology for Lake Livingston Eutrophication
Quantitative Analysis, (May 1975) .
14. Influence of Land Use on Stream Nutrient Levels, Environmental
Protection Agency Publication EPA-600/3-76-014.
15. Aubertin, Smith, Patric, Quantity and Quality of Stream Flow
After Urea Fertilization on a Forested Watershed: First Year
Results, Forest Service Gen. Tech. Rep. NE-3, (1973).
2-116
-------
16. Borman, et. al., Nutrient Loss Accelerated by Clearcutting Of A
Forest Ecosystem, Science, 159:882-4 (1968).
17. Clark, Guide, Pheiffer, Nutrient Transport and Accountability In
The Lower Susquehanna River Basin, Environmental Protection Agency
(Annapolis Field Office), Tech. Rep. 60 (October 1974).
18. Cleveland, Ramsey, Walters, Storm Water Pollution From Urban Land
Activity, Federal Water Quality Administration, 11024-06/70
(June 1970).
19. Harms, Dornbush, Anderson, Physical and Chemical Quality of
Agricultural Runoff, Journal Water Pollution Control Federation
Vol. 46, No. 11 (November 1974).
v
20. Hetling, Sykes, Sources of Nutrients in Canadanago Lake, Journal
Water Pollution Control Federation, Vol. 45, No. 1 (January 1973).
21. Hydroscience, Time Variable Water Quality Analysis and Related
Studies of the Upper Delaware River, For Delaware River Basin
Commission (January 1975).
22. Hydroscience, Water Quality Analysis of the West Branch of the
Delaware River, Por the New York State Department of Environmental
Conservation (April 1975).
23. Jaworski, Nutrients in the Potomac River Basin, Chesapeake
Technical Support Laboratory (May 1969).
24. Likens, Water and Nutrient Budgets for Cayuga Lake, New York,
Cornell University Water Resources Center (March 1974).
25. Loehr, Characteristics and Comparitive Magnitude of Non-Point
Sources, Journal Water Pollution Control Federatipn, Vol. 46,
No. 8 (August 1974).
2 - 117
-------
26. Owens, Garland, Hart, Wood, Nutrient Budgets in Rivers, Symp.
Zool. Soc. Land. No. 29 (1972).
27. Uttermaak, Chapin, Green, Estimating Nutrient Loadings of Lakes
From Non-Point Sources,, Environmental Protection Agency Publication
EPA-660/3-74-020 (August 1974).
28. Hydroscience, Preliminary Investigation of the Effects of Forest
Management Operations on Apalachicola Bay3 Florida, (March 1975).
29. Palmer, Non-Point Source Pollution in the Potomac River Basin,
(1975).
30. Sylvester, (1960).
31. Neil, (1967).
32. Hydroscience, Water Quality Analysis of the Potomac .River,
(July 1976).
33. ,Wanielista, Non-Point Source Effects, (January 1967).
34. Jaworski, Clark, Feignor, Water Resources and Water Supply
Study of the Potomac Estuary.
35. Process, Procedures and Methods to Control Pollution Resulting
from Silvercultural Activity, Environmental Protection Agency
Publication 430/9-73-010.
36. Proceedings of the 3rd Federal Interagency Sedimentation
Conference (1976).
37. Analysis of Non-Point Source Pollutants in the Missouri Basin
Region, Environmental Protection Agency Publication 600/S-75-004
(March 1975).
2 - 118
-------
38. Sawyer, (1947).
39. McElroy, Chiu, Nebgen, Aleti, Bennet, Loading Functions For
Assessment of Water Pollution From Non-Point Sources, Environmental
Protection Agency Publication 600/2-76-151 (May 1976).
40. O'Connor, Dobbins, The Mechanism of Reaeration in Natural Streams,
Transactions American Society of Civil Engineers, Vol. 123 (1956).
41. Johns Hopkins University, Coliform Bacteria Study (In Progress).
2 - 119
-------
CHAPTER 3
PROCEDURES FOR ASSESSMENT OF URBAN POLLUTANT SOURCES AND LOADINGS
3.1 Introduction
This chapter discusses procedures for the assessment of waste loads
generated in urban areas at a higher level of refinement and detail than
employed in the preliminary analysis described in Chapter 2. Since the
assessment methodology for continuous point sources, at the higher level
of refinement, is very similar to procedures presented in Chapter 2,
Chapter 3 emphasizes procedures for those urban loads which enter receiving
waters as intermittent point sources, and provides a limited discussion
of the applicability of these procedures for estimating the impact of
non-point source urban loads. A more complete discussion of the assessment
methodologies for nonpoint source non-urban loads is presented in detail
in Chapter 4.
3.2 Identification of Level of Sophistication Required
The output from a preliminary assessment as discussed in Chapter 2, is a
broad identification of major pollutant sources within an urban area
along with a perspective on the relative magnitude of the pollutant
loads generated, the temporal and spatial distribution of these loads,
and a preliminary assessment of the impact of these loads on water
quality problems within the planning area.
Once the major pollutant loads have been identified and can be attributed
to sources for which control measures are possible, assessment procedures
with higher levels of sophistication should be employed to refine the
previous loading and impact estimates. At higher levels of refinement,
it is appropriate to consider the changes in the temporal and spatial
distribution and magnitude of loads from sewered and non-sewered urban
3-1
-------
areas. This allows the planners to further differentiate mass pollutant
loadings as modified by the nature and extent of storm and combined
sewer conveyence, retention and treatment facilities.
Although predictive methodologies and analytical approaches with a high
level of sophistication and detail are described in Appendix A of this
manual, the procedures recommended for the level of assessment in this
chapter are the simplest of the available techniques that will allow
estimation of pollutant loadings and impacts necessary to support the
decisions that must be made. While it is generally accepted that higher
levels of sophistication will permit more accurate or reliable pollutant
load quantification and impact analyses, the decision to use highly
sophisticated procedures for problem assessment must be tempered with an
understanding of the inherent weaknesses and limitations of the overall
analysis. These limitations stem from measurement errors in rainfall
related pollutant loadings, from the complex nature of pollutant transport
mechanisms within urban drainage areas and from the wide range of physical
and chemical transformations that occur in the receiving waters.
Another point that must be considered in this second level of refinement
in the analysis is the choice between very precise and accurate estimates
of the loads from a small number of events or a less refined analysis of
longer term loading histories. This choice often depends on such factors
as the availability of historical rainfall and stream flow data, the
physical characteristics of the drainage area and the water quality
standards of the receiving water.
The justification for detailed analysis at higher levels of sophistication
is related to the environmental and economic risks involved in decisions
made from analyses with lower levels of precision and refinement. These
risks should be balanced against the cost for data collection and analysis
associated with the sophisticated procedures. "Balanced analytical
frameworks and data collection activities should be developed for the
major loading components and associated receiving water responses.
3-2
-------
3.2.1 Identification of Appropriate Time Scale
Pollutant loadings from urban areas may be separated into two categories:
those which are related to storm events and those which are not. Storm
events are highly variable in magnitude and transient in nature, occurring
randomly in time. Combined and separate storm sewer overflows and
surface runoff through natural channels are generated by storm events,
and therefore have similar characteristics, though different in magnitude.
The component of rainfall which is lost to soil infiltration may also
generate loads, via the transport or leaching of soluble pollutants.
The characteristics of loads entering a stream from groundwater are
quite different from the loads associated with surface runoff. All or
part of these percolating loads may remain as groundwater, or infiltrate
sewer lines. That portion which does enter the receiving water could
tend to do so over an extended period of time and over an extended area.
Thus, storm events can generate highly-variable transient loads which
are discharged directly to the receiving water as well as diffuse
indirect loads which enter the receiving water through groundwater
inflow attenuated beyond the actual rain event.
Urban loadings not associated with storm events include the typical
point source discharges from municipal and industrial treatment plants,
continuous discharges of raw sewage from faulty regulators, inadequate
or partially filled interceptors, treatment plant bypasses, and groundwater
inflow pollutant loadings from sources such as improperly functioning
septic tank leach fields and improperly designed or operated landfills.
Such loadings are more or less continuous, except for the diurnal activity
of municipal and industrial sources and seasonal activities from specific
industries. Urban pollutant loadings, therefore, are time dependent to
varying degrees.
Waste loads with a low order of time dependence may be characterized on
a yearly basis (pounds/year), and prorated linearly down to some time
interval of interest (pounds/month, pounds/day). Except for cases where
significant seasonal changes occur, such as population movement in
vacation areas or seasonal industrial activity, such prorated daily or
3-3
-------
monthly loading rates will be fairly representative of the actual loading
rates from the source during these periods.
For transient storm generated loads, this is not the case. A yearly
stormwater loading rate represents the sum of all individual storm loads
which have occurred throughout the year. If such annual loads are
prorated down to monthly or daily loading rates, the resulting loads are'
artificial, since the distribution of rainfall is not uniform. In the
characterization of storm loads, an average annual loading rate may be
used as a measure of the relative impact of storm runoff. For example
in a case where sediment deposits in the receiving water are a primary
concern, the cumulative effect of all storm overflows is more significant
than that of an individual event or a specific period within an event.
For this case, it is unimportant whether a prorated daily or monthly
loading rate reflects the instantaneous rate during that period, as long
as the cumulative load calculated by using these rates is representative
of the long term loading to the receiving water. Long term loading
characterizations are appropriate where the impacts of storm overflows
are not confined to occurrences during individual storm events. Impacts
may be observed at any time, and possibly become most severe only during
non-storm periods.
Where water quality impacts from stormwater overflows are as transient
as the occurrence of the overflows, the long term average loading
becomes much less important, and represents only the first step in the
characterization of storm runoff. Coliform organisms, which are present
in storm overflows and have relatively rapid die-off rates in natural
waters, may be used to illustrate this point. If a coliform load enters
a receiving water during a 6-hour storm event, the peak concentration
observed in the receiving water would generally be restricted to that
order of time. Based on the magnitude of the load, the transport
characteristics of the drainage area and receiving water, and the die-
off rate of the coliforms, the total impact will often be dissipated
before the next storm occurs. In this case, yearly or monthly average
loading rates do not adequately indicate the actual load during a storm.
Further, they do not provide information on whether the resulting receiving
3-4
-------
water concentrations are objectionable, or how often concentrations in
excess of stream standards or water quality objectives may be observed.
These average loads for pollutants with short-term transient impacts
can be useful for identifying the significance of a particular source or
the magnitude of a problem. Reliable assessment, however, requires a
greater level of detail in the definition of such loads.
Figure 3-1 illustrates various levels of refinement which might be
employed in the definition of transient stormwater loads. It represents
the transition from a relatively simple average yearly loading to a
quite detailed representation of storm runoff accomplished by introducing
additional temporal detail. The level of refinement proceeds as follows:
Level 1. Average yearly storm load
Level 2. Actual event distribution
Level 3. Variation within events
Level 1 uses the average annual stormwater loading rate, W , as was used in
Chapter 2. W is calculated by determining the total storm load during
the year (pounds), and assuming that it occurs continuously (during both
rain and non-rain periods). Confidence in the value of W would require
the monitoring of all storm loads over a period of several years. This
is impractical within the 208 planning and assessment time frame. Most
storm analysis techniques must rely, at least initially, on estimates of
such values extrapolated from other studies or projected from data
secured from limited areas and limited time periods.
Level 2 considers the actual temporal distribution of stormwater events. It
indicates the variability of the pollutant load from event to event. It does
not, however, indicate how the load varies within each event. The variation
of runoff load per event is due primarily to the amount of rainfall occurring
during each event. It is also due to the variation in time between storms
which affect surface debris inventory, and to seasonal changes in debris
accumulation in the drainage basin (e.g., leaf fall, spring fertilization,
etc.).
Level 3 describes the actual runoff loading rate for all storm and for any
time within each storm, whether it be hour by hour or minute by minute
3-5
-------
DRAINAGE
BASIN
COMBINE
OVERFLOWS =f (RAIN EVENTS)
SEPARATE STORM
SEWER
DISCHARGES
DRY WEATHER
TREATMENT SYSTEM
POINT
SOURCE
LOAD
(CONTINUOUS
LOAD)
TOTAL YEARLY Wo
STORM LOAD - LBS/HR
(COMPARABLE TO A]
LOADJ
to
1
3
-J
ft: LBS/HR
fc
§
1
<0
LBS/HR
ACTUAL EVENT DISTRIBUTION
OF'LOAD
..—n—.iC
AV6. LOAD PER EVENT, W
nnn
'lriTrt
H fl FT
r~\ Pi TT
ACTUAL DISTRIBUTION OF
LOAD WITHIN EVENT (IST. FLUSH, ETC.)
-AV6.'LOAD PER EVENT, WR
A--
/ YEAR
FIGURE 3-1
VARIOUS LEVELS OF DETAIL IN
STORMWATER LOAD CHARACTERIZATION
3-6
-------
characterization. This level indicates the "first flush" effects,
varying storm patterns, and varying intensity within the storms.
When it becomes inappropriate to use the long term average pollutant
loading rate, W , in an impact analysis, then some higher level of
stormwater loading definition must be provided. Selection of an
appropriate level of detail in definition of storm loads is best dictated
in assessment studies by receiving water impacts. Pollutants discharged
to receiving waters have characteristic time and space scales associated
with the impacts they cause. These scales are illustrated by Figures 3-
2 and 3-3, and can be used to provide guidance in determining the time
scale of the averaging which is appropriate.
Thus, while suspended solids loads may, in most cases, be characterized
on an annual basis, more reactive contaminants Ccoliform organisms,
oxygen consuming materials) will usually require definition on a scale
in the range of hours. Note that waste load definition on a scale finer
in detail than one to several hours (approximately the scale of storm
events) is not necessary for the evaluation of transient water quality
impacts. Assessment studies will, therefore, not normally require load
definition in greater detail than that represented by Level 2 in Figure
3-1.
Urban areas generate both continuous and intermittent point source
wastewater loadings. The continuous point source loads will now be
discussed. The intermittent point source loads are discussed in Section
3.4.
3.3 Characterization of Continuous Urban Point Source Loads
The methodology for characterizing continuous point source loads described
in Chapter 2 remains appropriate at the higher levels of refinement
discussed in this chapter. The data should be sufficient to allow for a
reliable estimate of continuous point source loads. These loads are the
most obvious in an urban area, they are usually important, and information
will usually be available for adequate characterization.
3-7
-------
SECONDS
10'
10s
10°
10'
10°
10'
FLOATABLES
BACTERIA
DISSOLVED OXYGEN
SUSPENDED SOLIDS
NUTRIENTS
ACUTE TOXIC EFFECTS
DISSOLVED SOLIDS
LONG TERM
TOXIC EFFECT
I
HOUR
DAY
MONTH
YEAR
WEEK
SEASON
DECADE
FIGURE 3-2
TIME SCALES
STORM RUNOFF WATER QUALITY PROBLEMS
3-8
-------
HYDRAULIC DESIGN
FLOATABLES
BACTERIA
SUSPENDED SOLIDS
DISSOLVED OXYGEN
NUTRIENTS
TOXIC EFFECTS
DISSOLVED SOLIDS
10"
10"
I 9 FT) (SOFT)
10''
(SCO FT)
10'
EFFECTIVE DISTANCE-MILES
10*
IOJ
-LOCAL -
-REGION-
-BASIN-
FIGURE 3-3
SPACE SCALES
STORM RUNOFF WATER QUALITY PROBLEMS
3-9
-------
The assessment of waste loads from an urban area seeks to identify the
relative significance of loads from different sources. Since many of
the urban loads (intermittent point sources, non-point loads) will
require characterization by estimating techniques, the overall assessment
will be strengthened by accurately characterizing those loads for which
an adequate data base exists. Municipal and industrial point source
discharges usually fall into this category.
3.3.1 Municipal Continuous Point Loads
As described in Chapter 2, waste loads from municipal treatment facilities
should be well quantified and documented. Sources of such data accessible
to the 208 Agency include treatment plant records, state or local
regulatory agency records, EPA NPDES (National Pollution Discharge
Elimination System) permit data or monitoring reports. An additional
source of data on municipal and other point source loads may be found in
study reports for 201 Facilities Plans and for 303-(e) Basin Plans,
where these have been completed in the area. The Regional EPA offices
maintain lists of completed basin plans for their region. These plans
will normally contain, in addition to data on point source loads,
information on water quality standards and objectives and on allocations
of waste loads from point sources.
There is a class of municipal continuous waste loads which will not
normally be documented or easily identified, but which may be significant
sources of load in some areas. Many cities with combined sewer systems
discharge unmonitored waste loads continuously as a result of defective
or improperly operated regulators and bypasses, partially filled
interceptors, or interceptors whose capacity is exceeded by normal dry
weather flows during some period of the day. Dry weather overflow data
for these discharges will not normally be available but it may be
possible to estimate them. Public works or sewer maintenance departments
or regulator and interceptor maintenance crews are sources of information.
Urban areas with separate sewer systems may also have significant
discharges from the sanitary sewer systems. During periods when the
groundwater tables are high, significant groundwater infiltration often
3-10
-------
occurs and excess flow from the sanitary sewers may be bypassed at the
plant or at upstream locations, thereby producing an often overlooked
pollutant load to the receiving stream. In addition, separate sewered
areas may have continuous discharges from storm sewers caused by
unauthorized connections.
3.3.2 Industrial Continuous Point Loads
With the enactment of the Water Pollution Control Act Amendments of 1972
>.
(PL 92-500) the NPDES program was established (1). With this program,
the Federal .Government established long term goals for industry to
achieve increased abatement of pollutants discharged to the nation's
waterways. As discussed in Chapter 2, all industries are required by
law to obtain a discharge permit, and to continually report to the state
and/or federal agency the quality of the discharge to the receiving
water. The permit indicates the effluent limit for discharges to the
receiving water. The compliance monitoring programs mandated by NPDES
report regularly on the actual discharges.
As with the municipal point source loads, there should be a sufficient
amount of data available to allow for a determination of existing
industrial loadings. Discharge permit requirements or results of
monitoring programs can be obtained from the EPA Regional Office, the
state regulatory agency, or possibly from the specific industrial
dischargers. Most of the present effluent limits are interim in nature,
and the Federal Government has set a specific time table during which
.certain effluent requirements must be met. Current regulations require
that all industries achieve Best Practicable Treatment (BPT) by 1977 and
Best Available Treatment (BAT) by 1983. To provide the 208 planner with
a basis for making estimates of these future industrial loadings,
effluent concentrations for some typical industries are provided.
Each industry is assigned a code number by the Department of Commerce,
depending on the specific products which it produces. The first two
digits of the Standard Industrial Classification (SIC) Codes for a few
sample industries are as follows:
3-11
-------
SIC Type Industry
20 Food and Kindered Products
22 Textile Mill Products
26 Paper and Allied Products
28 Chemical and Allied Products
29 Petroleum and Coal Products
33 Primary Metal Products
The effluent pollutant concentrations to be expected under the different
levels of removal for each SIC Industry type for both BPT and BAT are
presented in Tables 3-1 and 3-2, respectively. It must be emphasized
that the mean effluent characteristics shown in these tables represent
only approximately the average discharges for each industry. The actual
pollutant discharges will vary widely from one sub-category to another
within a given industry. There can be a number of different types of
plants within a specific industry with differing manufacturing processes
and products. An additional factor is the varying water usage per unit
of production from plant to plant. Therefore, these estimates should {
not be taken as characteristic of an entire industry. They provide only
a rough estimate of the mean effluent pollutant concentration. Additional
guidance for estimating such effluent concentration can be obtained from
the EPA Development Document for a specific industry which describes the
basis on which the discharge limitations were established (2 thru 14).
It should be noted that all of the effluent guidelines are not finalized
and that many industries are in negotiations with EPA concerning the
validity of the current effluent limits. Therefore, the effluent
concentrations in Tables 3-1 and 3-2 should only be used if no other
information is available.
In instances where the receiving stream which receives the industrial
discharge is classified as "water quality limited", the EPA must make effluent
allocations for each industry on a case by case basis. Generally, such
allocations will differ from the values discussed above, and will be
written into the permit along with a compliance schedule for meeting the
allocation.
3-12
-------
TABLE 3-1
TYPICAL INDUSTRIAL EFFLUENT CONCENTRATIONS
BPT - "1977"
APPROXIMATE MEAN EFFLUENT CHARACTERISTICS
(in mg/1)
(a)
Parameter
TSS
BODC
5
COD
TDS
Cl
Total-P
Total-N
Lead
Zinc
Cadmium
Oil
20
Food
40(b)
29Cb)
135
-
565
17
50
—
—
_
10(b)
22
Textiles
49(b:i
22(b)
225^
700
25
2
2
.03
5
.005
10
26
Paper
ro(b)
DO
39(b:>
156
3785
135
-
_
_
—
_
_
28 29
Chemicals .Petroleum
40 ^ lO00
30 15
1400 (^ 102 (b)
4350
-
5
20 70
2(b)
0.25
0.225^
Tr(b) ,Cb)
JLO O
33
Metals
20 Cb)
38Ub)
-
-
-
.50
62 ^
.25^
.25^
,15Cb)
'500
fal
^ "^Represents an approximate estimate of the mean effluent concentrations
for each industry. The pollutant concentration could vary widely within
an industry as a result of varying water usages.
^ ^Concentrations developed from effluent guidelines which exist for these
parameters, other concentrations were obtained from any existing treatment
plant data found in the Development Documents (2-14).
3-13
-------
TABLE 3-2
TYPICAL INDUSTRIAL EFFLUENT CONCENTRATIONS
BAT - "1983"
APPROXIMATE MEAN EFFLUENT CHARACTERISTICS
(in rag/1)
la)
Parameter
TSS
BOD5
COD
TDS
Cl
Total-P
Total-N
Lead
Zinc
Cadmium
Oil
20
Food
10 CO)
•7 00
/
48
-
565
1.2
9 ^)
-
_
_
10 ^)
22
Textiles
8 ^)
11 CO)-
7200
700
25
2
2
.03
5
.005
10
26
Paper
9*00
Zo
22^*0
88
3785
135
—
_
-
_
_
«
28
Chemicals
i ?(b)
lo
15
460^
4350
-
3
3
x(b)
oc 00
. Zo
.05 ^)
3
29
Petroleum
5 ^)
5 ^)
26 ^)
-
-
_
28
-
_
_
1.35 »)
33
Metals
5 CO)
4Cb)
-
-
0
5 ^)
0(b)
0(b)
0Cb)
s CO)
(a)
(b)
Represents an approximate estimate of the mean effluent concentrations
for each industry. The pollutant concentration could vary widely within
an industry as a result of varying water usages.
Concentrations developed from effluent guidelines which exist for these
parameters, other concentrations were obtained from any existing treatment
plant data found in the Development Documents (2-14).
3-14
-------
3.3.3 Need for Monitoring
Specific monitoring efforts for point source continuous discharges may
be adviseable or necessary during an assessment study. Although, as
indicated earlier, it is likely that a fairly comprehensive data base on
such loads is available, efforts to provide supplementary data by means
of a monitoring program may be indicated for a number of reasons. Some
of the more often encountered reasons are:
1. Need to verify data reported from municipal and industrial
sources
2« Need to develop temporal and special data for complex situations
where ongoing stream surveys are being performed.
3. Need to quantify impacts from previously unidentified sources,
such as overflows caused by severe infiltration of separate
sanitary collection systems, faulty regulator, operations in
combined sewer systems, partially filled interceptors, or
unauthorized connections to storm sewers
4. Need to obtain specific contaminant information for cases
where appropriate sources were monitored but contaminants of
interest were not included.
3.4 Characterization of Intermittent Point Source Loads
Because of their variability, intermittent point source loads require
the use of unique estimating procedures for adequate quantification.
Extensive data on storm runoff loadings have been obtained in recent
years and have been reported in the literature (15-19). These
provide an immediate source of information, but are not a substitute for
local data and analysis. Unless reported data have been collected in
the study area, local data must be collected and used in developing
estimates of storm loads. The need for adequate local data is based
upon the following factors:
1. Differences in rainfall frequency, intensity, and duration
along with drainage area characteristics significantly influence
storm loads.
3-15
-------
2. Significant variations in loads from individual storms are
observed in the same area.
3. Studies which develop loading data generally cover relatively
short periods of time compared with the long term patterns of
rainfall in any area.
The most important factor in the generation of intermittent (storm)
loads is rainfall. Rainfall data for an area should be among the first
set of local data obtained and analyzed. All of the load estimating
methods employ rainfall as the fundamental data input.
Hourly rainfall records for U.S. Weather Bureau stations in the study
area may be obtained from the National Weather Records Center, Asheville,
North Carolina, either on magnetic tape or on punched cards. For a long
term period, the cost of such records is approximately $100 per gage.
In addition, data from local rain gages may be obtained from sources
within the study area, reduced to an hourly record and utilized in a
similar fashion. Data from the U.S. Weather Bureau stations should
always be analyzed, because the data are reliable and will generally
cover the longest historical record. Data from local gages are often an
important source of more area-specific information and should be analyzed
whenever available. The actual use of the data depends upon the
methodology employed, and is described further in Sections 3.4.3 and
3.4.4.
Other data inputs required are the drainage basin and land use
characteristics of the study area. For urban areas, this can
be initally summarized (as illustrated in Figure 3-4) by the relative
distribution of land use classifications (residential, industrial,
commercial, open, etc.) served by basic conveyance systems (combined
sewers, separate storm sewers, natural conveyances). Appendix C and the
Nationwide Evaluation of Combined Sewer Overflows and Urban Stormwater
Discharges, Vol. II: Cost Assessment and Impacts (16) describe in
detail the available sources of this information and the procedures for
its use.
3-16
-------
NATURAL TRIBUTARY
DRAINAGE AREA
TREATMENT PLANT —7
LATOR V
\1 ""V rf
!_—^Lcbci
INDUSTRIAL
COMPLEX
(1-4)
LAND USE
BREAKDOWN
RESIDENTIAL LO. OENS.
MED. DENS.
HI. OENS.
COMMERICAL
INDUSTRIAL
RESIDUALS DISPOSAL
OPEN
% OF AREA
COMBINED
SEWERS
•
SEPARATE
STORM
SEWERS
NATURAL
CONVEYANCE
TOTAL AREA.
FIGURE 3-4
DRAINAGE BASIN CHARACTERISTICS
3-17
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The amount of runoff from storms and the pollutant loads associated
with this runoff are determined by three basic elements:
1. Rainfall
2. Land use
3. The extent and type of stormwater collection and conveyance
systems.
Each methodology described in this chapter employs a procedure to calculate
flow and loads based on these inputs. The more sophisticated the
methodology, the greater the detail required for the characterization of
the drainage area. Any methodology may use initial estimates for
relationships which convert rainfall and land use data into runoff flows
and loads. Specific local data are needed to confirm or refine these
relationships.
3.4.1 Identification of Appropriate Methodology
In general, there is no single methodology which is uniquely appropriate
for the assessment of urban storm pollutant loadings in all 208 areas.
The utility of each method is dictated by many factors, some of which
include:
1. Local conditions
a. land use
b. conveyance system
c. seasonal variation of rainfall
2. Availability of local data
a. water quality data
b. hydraulic data
c. raingage data
d. demographic data
3. Type of receiving water
a. stream
b. estuary
c. lake
d. coastal water
3-18
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4. Water quality problems
a. dissolved oxygen
b. public health
c. eutrophi cation
d. other (IDS, TSS, etc.)
5. Time scale of water quality problems
a. transient (hour, days)
b. longer term (month, season, year)
6. Decisions involved
a. feasibility of control
b. economic risk
c. environmental risk
7. Study constraints
a. time
b. cost
Specific methodologies which employ various levels of detail are used as
part of the framework in which an urban loading assessment is .performed.
Examples of appropriate methodologies for storm loads are presented and
described later in this chapter. The transient storm loads generated by
these methodologies, together with the continuous point loads, are then
used to assess receiving water impacts, as described in Chapter 5.
3.4.1.1 Selection of Suitable Estimation Procedures
The methods which are available to characterize and quantify stormwater
loads all include the following essential elements:
1. Rainfall
2. Drainage basin characterization
3. Runoff quality and flow characterization
A major difference between the available methods lies in the detail in
which the elements are represented. High levels of detail in the analysis
require more definition of the drainage basin along with an associated
increase in input data requirements. All of the methods attempt to
describe the relationship between the runoff load and the various elements
which influence it. A partial list of these elements includes:
3-19
-------
1. Separate or combined sewer system
2. Collection system characteristics
3. Areal variability of rainfall
4. Rainfall intensity
5. Rainfall duration
6. Time between storms
7. Degree of imperviousness of drainage area
8. Drainage basin slope
9. Soil type, vegetative cover, erosion control practices
10. Land use: commercial, industrial, residential, open space,
etc.
11. Population density
12. Surface pollutant accumulation and decay rate
13. Street cleaning frequency
Some of the simpler methods use empirical coefficients which aggregate
many of the above influences. Other more sophisticated methods attempt
to provide refined loading estimates by incorporating cause-effect
relationships for the above elements.
Examples of more sophisticated simulation models which have been applied
to estimate stormwater loads include: NFS Model, STORM, SWMM (continuous
version). These and other applicable models are included in a discussion
presented in Appendix A (NFS Model is discussed in Chapter 4) which describes
the salient features of each model and its applicability for estimation
of storm loads and receiving water impact.
The notable aspect of each of the models listed above is that they are
continuous simulators. That is, they re-enact the stormwater process
Cthe sequence of storm events over some extended period of time). They
do not concentrate on single storm events. It is a knowledge of this
event sequence and its impact, which often provides the best information
and perspective for assessment studies.
Any method requires calibration before it can be used reliably. That
is, samples of the runoff must be collected for a sufficient number of
runoff events covering a variety of conditions so that consistent cause-
3-20
-------
effect relationships can be established. Once calibrated and verified,
the methods can be used to make estimates of loads beyond the limited
data set used in the calibration-verification procedure.
Where local data needed to calibrate the above models is lacking, estimates
or default values for essential parameters can be used for the
characterization of the cause-effect relationships in the models. It is
well to recognize, however, that the default values were developed based
on experience in a particular study area and are not universally
applicable. Local effects and conditions have a significant influence,
and without at least some local data for comparison, high degrees of
confidence in calculated results may not be warranted.
Two simplified approaches to the characterization of storm loads are
described in detail in this chapter. One is a simulation approach which
represents loadings by storm events. The other estimating procedure
presents a purely statistical method for the assessment of runoff and
treatment. Each incorporates a level of detail which is appropriate for
assessment studies, and permits the examination of long term
characteristics. While both permit estimates to be made without local
data, the use of such data for calibration to local rainfall, runoff
and quality characteristics will produce load estimates with a higher
degree of confidence.
3.4.1.2 Levels of Accuracy Required in Storm Load Characterization
At each level of detail in the stormwater load characterization (e.g.
yearly, seasonally, monthly, event by event, etc.) described in Figure
3-1, there is a certain level of accuracy provided by the various
calculation techniques. Two types of accuracy can be considered in
applying available techniques: (a) event accuracy and (b) statistical
accuracy for a long term sequence of events.
Many simulator models attempt to correctly relate phenomena in the
drainage area to their associated effect on stormwater loads. They
require calibration to define a consistent set of coefficients which
establish the magnitude of the parameters in the cause-effect
3-21
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relationships. In order to estimate these parameters, a sufficient
number of stormwater overflow events are monitored. Then the model
coefficients are estimated and adjusted until there is a good agreement
between the predicted load distributions within individual events and
the actual observed values. The simulator is then considered calibrated.
If other events with different rainfall properties agree equally well
with observed data, the simulator can be considered to be verified. A
good calibration requires comparison with a number of significantly
different storm events, such that there is a reasonable agreement between
actual and calculated distributions of loads for events which cover a
wide range of relevant magnitudes. This calibration may be quite difficult
in that it requires substantial amounts of data on drainage area
characteristics, storm flow, and quality; all for a sufficiently large
number of events. Where the calibration is accomplished for only a few
events, the confidence in the prediction would be high only for conditions
similar to those used in the calibration. For significantly different
event conditions, such as more or less intense storms, differing durations,
longer or shorter periods between storms, etc., there would be less
confidence in the prediction.
Event accuracy reflects a very high level of definition of virtually
all of the significant cause and effect relationships which influence
stormwater loads. Both data requirements and the analytical effort
required to achieve a satisfactory degree of event accuracy are high.
Statistical process accuracy is directed toward the accurate statistical
representation of stormwater loads over extended time periods. Individual
storm events may be either underestimated or overestimated, however when
the statistical summary of the long term sequence of events can be
appropriately characterized for a period of interest, the model output
can be considered to have statistical accuracy.
Load characterizations of this type are often appropriate in the second
level of problem assessment since at this level of analysis it is not
always necessary to have an accurate and complete understanding of the
mechanisms which actually determine storm loads. Statistical summaries,
which include the mean, the coefficient of variation, and the frequency
3-22
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distribution of the load are sufficient information for a reasonable and
complete assessment of present conditions, and also for an estimate of
the effect of certain control measures.
In some cases, the areal variability of rainfall and the insufficient
number and distribution of rain gages introduce errors in storm event
calibration. Such errors become less important, however, when the
models are directed toward reproduction of the longer term process
statistics rather than toward individual events. The "continuous"
versions of some of the available simulator models are intended to
stress the longer term effects rather than the detail of single events.
Figure 3-5 illustrates a manner in which loads from a long term sequence
of storm events may be analyzed to summarize those features of the storm
process which are significant for an assessment study. Pollutant loads
generated by individual storm events are estimated on the basis of the
properties of- the storm event causing the runoff. The magnitude and
time of occurrence are determined as illustrated by Figure 3-5(a).
Statistical procedures may be used to develop a probability density
function representing the frequency of occurrence of loads of various
magnitude, as illustrated by Figure 3-5(b). Providing the period of
record used for analysis is long enough to yield statistically significant
results, this analysis may be made for annual periods, specific seasons
of the year or individual months of interest. Additional discussion on
the development of these probability density functions is provided in
Sections 3.4.3 and 3.4.4.
3.4.1.3 Levels of Spatial Detail Required in Storm Load
Characterization
Another important aspect of stormwater load characterization is the
spatial detail with which loads are defined. There are situations where
either the event accuracy or the statistical process accuracy will be
reduced because the load estimating methodology does not adequately
describe the spatial distribution of stormwater loads from an area.
Included among the conditions which will require increased levels of
detail in the definition of waste load input locations are the following:
3-23
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(a) SINGLE EVENT DISTRIBUTION
I<
03
vl
A
TIME
(b) STATISTICAL REPRESENTATION OF LOADING FROM SEVERAL EVENTS
-J 100
I
I
I
LOAD LBS/HR
FIGURE 3-5
REPRESENTATIONS OF A LONG TERM SEQUENCE
OF STORM POLLUTANT LOADS
5-24
-------
1. Aggregating smaller sub-catchments into a single large drainage
area may be difficult for a combined sewer collection system
with multiple overflow locations. The estimation of an "average"
interceptor capacity representative of the entire drainage
area will introduce error in the load estimates for some
areas.
2. Storms in an area may be highly localized and result in
significant areal variability of rainfall. The delineation of
smaller sub-catchments will be necessary to increase the
accuracy of load estimates in .some cases.
3. For some receiving waters, it will be necessary to characterize
storm loads according to their actual point of discharge, in
order to make an accurate assessment of the impact of these
multiple loads on receiving water quality.
There are, however, conditions under which it is appropriate to ignore
such spatial detail without introducing unacceptable error into the
estimation of storm loadings. This is particularly true for analyses
being performed at an assessment level of detail and, for water quality
analyses where longer term statistical process accuracy is the objective
and where the assumption that the rainfall occurs uniformly throughout
the entire study area is reasonable.
Due to the areal distribution of rainfall, different sub-catchments of a
drainage basin may have considerably different runoff loads during a
particular storm. The longer term frequency distributions of the rainfall
on each of the subcatchments, however, are more likely to be similar,
and a larger area may be aggregated when determining long term runoff
flows and loads. Caution must be used, however, when aggregating different
subcatchments for the purpose of determining runoff flows and loads
during storms. The assumption that the rainfall is falling uniformly
and simultaneously throughout the area may cause a large overestimation
of the runoff flow and load that occurs during storms.
For impacts which are long term in nature, or for receiving waters
(tidal estuaries, for example) where significant mixing takes place, it
3-25
-------
is often adequate to ignore some of the spatial detail, even for analyses
with higher levels of refinement.
Figure 3-6 illustrates schematically the type of spatial aggregation of
individual loads which can often be made in assessment studies utilizing
the level of refinement discussed in this chapter. The loads from sub-
catchment sections one through five may be aggregated and assumed to
enter the receiving water at a single location-.
3.4.2 Characterization of Rainfall-Runoff Relationship and Runoff
Quality
The key element in making reliable storm load estimates with any of the
available methodologies is the determination of appropriate relationships
for the study area which describe the amount of rainfall which will
leave the area as runoff and the pollutant concentrations associated
with the runoff.
Both the statistical method and the simulator method later described in
this chapter require estimates of runoff quantity and quality. Techniques
for determining both an average runoff coefficient and representative
pollutant concentrations in storm flows for use in both these methods
are presented in this section.
3.4.2.1 Estimation of Runoff Coefficient
The volumetric runoff coefficient, C , measures the fraction of the
storm volume which reaches the conveyance system as runoff. Because the
use of a volumetric runoff coefficient aggregates the combined effects
of variable storm properties and drainage basin characteristics, it is
not treated as a constant, but as a random variable. The purpose of
this section is to determine an average value, GV, which may be employed
in storm load assessments.
It is preferable to estimate Cv by comparing raingage data to runoff
monitored during corresponding storms. Flow measurements should be
taken within the sewer system and/or the natural conveyance channels.
Flow data that are developed can include faulty data because of measuring
3-26
-------
AGGREGATED
STORMWATER LOAD
©
STORM 'SEV.'ER -v
V
m
//
i
7j
7
'/.
I
'/
/
y.
//
h
/
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~i« ~i
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i
i
i
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i
!
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1
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y-.STORM SEWER
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"v-v '; -';' ''"• '•- '"'-
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STORM AND /
COMBINED /I"
SEWER / L
OVERFLOWS-/
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<• •• C 4*' ",' "
rr**~~
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-------
equipment and maintenance weaknesses, therefore data and maintenance
records should be screened carefully to identify such occurences. It is
incorrect to assume that, because two significantly different
runoff volumes are recorded for similar rainfall events, the equipment
is necessarily faulty. The two storms may have occured with different
antecedent soil conditions or with a different areal extent and spatial
distribution of rainfall with respect to the raingage recording the
events.
A sufficiently large number of observations of runoff quantity for at
least one representative location for which drainage area characteristics
5
are well known would be required to develop a representative value for
the average runoff coefficient, C . In a statistical evaluation of
rain events performed by the National Oceanographic and Atmospheric
Administration (NOAA), one of the findings was that there is a 90 percent
confidence level in the expectation that 85 percent of the various
intensity and duration rain events for a given location will be experienced
within a 2.8 year period (20). It would therefore be a rather long term
and costly project to study even most of the possible rainfall events.
Some decision must be made on how long a study period should last and
how many events should be monitored.
From statistical sampling theory, the Central Limit Theorem states that
the distribution of sampled averages tends to become normal as the
number of samples increases, no matter what the distribution of the
variable being sampled (21). This property may be used to estimate the
number of storms necessary for an adequate estimate. This number is
dependent upon the variation of the parameter being measured (in this
case the runoff coefficient), the maximum desired error in the estimate
of the,average, and the confidence that one has that the sampled average
falls within the particular range. Figure 3-7 shows the relationship
between the number of storms monitored and the resulting level of accuracy.
The curves presented are based on a coefficient of variation of 0.75 for
the runoff coefficient, which appears to be a reasonably conservative
estimate based on observed data (22). In general, 20 to 40 storms will
provide adequate representation.-
3-28
-------
100
90
80
o5 70
UJ
UJ
50
50
O
UJ 40
2
OT 3°
UJ
20
10
NOTE:
= .75 FOR BOTH CURVES
90% CONFIDENCE LEVEL
58% CONFIDENCE LEVEL
10 20 30 40
N=NUMBER OF STORMS MONITORED
50
FIGURE 3-7
ERROR IN ESTIMATE OF AVERAGE
VERSUS NUMBER OF STORMS MONITORED
3-29
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When extensive monitoring is not feasible for a study
data is not available at the time an analysis is made, estimates may be
made from land use and drainage basin characteristics. The greater the
percentage of impervious surfaces in a watershed, the greater will be
the runoff for a given size storm. This is due to the reduction in the
amount of rainfall lost to infilitration. Relationships between the
percent impervious area and the runoff coefficient have been developed
from the analysis of published data and-are shown in Figure 3-8. These
include results averaged from eight cities (22) (the solid curves in
Figure 3-8) and the equation developed for use in the STORM simulation
model (24,25). The volumetric runoff coefficient, C ; is the ratio of
the runoff volume to the volume of the rainfall, and therefore accounts
for depression storage as well as infiltration. The equation in the STORM
simulation model, uses an average instantaneous runoff coefficient
and does not account for depression storage. In this model, a separate
adjustment is made to account for depression storage, as follows (15):
Land Use Depression Storage (in)
Impervious 0.0625
Pervious 0.25
For a given land use, the area weighted depression storage, (DS), in
inches, is:
DS = 0.25 - 0.1875 (Percent Impervious Area/100) (3-1)
When using the STORM equation, the depression storage should be subtracted
from the rainfall volume before multiplying by the runoff coefficient.
However, the depression storage correction may be too refined at this
level of analysis due to the variation in the data upon which both the
estimates of the volumetric and the instantaneous runoff coefficients
are based.
The percentage of impervious area in a drainage basin may be determined
by examining aerial photgraphs or detailed land use plans. This may be
a long and tedious task, however, particularly for large drainage areas.
Estimates may also be made on the basis of the general fraction of land
in different land use categories. Specific land use classifications are
3-30
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1.0
0.9
o.e
> 0.7
u
I °-6
o
li.
fc 0,6
O
o
t o-4
o
o: 0.3
O.2
O.I
LIMIT OF RUNOFF COEFFICIENT
TIGHT SOIL OR STEEP LAND
•STORM MODEL EQUATION
(24.25)
LOOSE SOILS OR FLAT LAND (22)
100% OPEN; TIGHT SOILS OR STEEP LAND
100% OPENjLOOSE SOILS OR FLAT LAND
1
10 • 20 30 40 50 60 70 80 90 100
PERCENT IMPERVIOUS AREA
FIGURE 3-8
RUNOFF COEFFICIENT DETERMINATION
FROM LAND COVER INFORMATION
3.31
-------
assigned an average percent impervious area as shown below. The indicated
values or other handbook estimates (26) may be modified or refined on
the basis of local information, past experience or field inspection
surveys.
Land Use Category Percent Impervious Area
Residential
Low Density 20
Medium Density 40
High Density 60
Commercial 80
Industrial 70
Institutional, Public 30
Open, Undeveloped 0
The percent impervious area for the entire drainage area is calculated
by taking a weighted average of the individual components of the area.
For example, assume an area has the following land use characteristics:
Low Density Residential 30%
• Medium Density Residential 20%
Comercial 10%
Industrial 10%
Institutional, Public 5%
Open, Undeveloped 25%
Total 100%
The overall percent impervious area would be:
Percent Impervious Area = (0.30) . (20) + (0.20) . (40)
+ (0.10) . (80) + (0.10) . (70)
+ (0.05) . (30) + (0.25) . (0)
= 30.5%
This value would be used in Figure 3-8 to determine the average runoff
coefficient, C .
3-32
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If information on the land use categories cannot be obtained, the percent
imperviousness in developed areas may be estimated from the population
density. Graham et_ al. (Washington, DC) (23), the American Public Works
Association (18) and Stankowski (New Jersey) (27) have developed equations
to predict imperviousness as a function.of population density. The
imperviousness is to be estimated for the developed portion of the
urbanized area only. The weighted average imperviousness and population
density were also calculated for nine Ontario cities(28). These results
are plotted on Figure 3-9 along with the three estimating curves (15).
If the New Jersey data, which is based on 567 municipalities, is selected
as a reasonable guideline, the equation used to estimate imperviousness
is:
Percent Impervious Area = 9.6 PD, CO.573-0.0391 log1QPDd) ^^
where:
PD, = population density in developed portion of the urbanized
area (persons/acre).
The percent impervious area is used to obtain the runoff coefficient,
Cy, from Figure 3-8.
Note that individual estimates of the runoff coefficient should be made
for areas served by combined sewers, separate sewers or natural
conveyance. This is because significant differences in pollutant
concentrations are found in the storm flows which enter receiving waters
from such areas.
The final component of flow which may be of interest in combined sewer
systems is the dry weather flow. This may be estimated as 100 gallons
per person-day, when more area specific data is not available.
3.4.2.2 Estimation of Runoff Pollutant Concentrations
The most reliable estimates of runoff pollutant concentrations are
obtained from extensive local monitoring programs. The most comprehensive
quality data from a monitoring program would reflect the changes in
concentration during various storm events for each overflow location.
3-33
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too
90
80
70
!j= 60
1
^ 50
40
30
20
10
PERSONS/HECTARE
10 20 30 40 50 60 TO 80
I I I I I T
I
I
I
LEGEND:
A WASHINGTON, O.C.
D ONTARIO
I
5 10 15 20 25 30
DEVELOPED POPULATION DENSITY, PDd, persons/acre
35
REFERENCE (IS)
FIGURE 3-9
IMPERVIOUSNESS AS A FUNCTION OF
DEVELOPED POPULATION DENSITY
3-34
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Information on variations in quality within a storm event will help to
identify the magnitude of the first-flush phenomenon. The measurement
of quality for each separate area would reflect the impact of the mix of
various land uses on the wastewater loads discharged.
The use of composite or grab samples from overflows may be substituted
in an assessment study for the complete time-history measurements which
would be costly and time consuming. This may cause a distortion in the
results, because the first-flush phenomenon, if it occurs, is not
acknowledged. The occurrence of a first-flush phenomenon is dependent
upon the size and characteristics of a catchment area and storm
characteristics. Grab or composite sampling will provide an insight
into the quality of the overflow only on an event averaged basis.
A sufficient number of storms must be monitored to adequately characterize
pollutant concentrations. The guidelines presented in Section 3.4.2.1
on the runoff coefficient may be used to determine the number of storms
to be monitored for quality estimates for specific catchments. Since
observed data (22) suggests that a reasonable estimate of the variation
of runoff concentrations between storms in a specific catchment is also
on the order of 0.75, Figure 3-7 can be used to estimate a general
requirement for sampling 20 to 40 storms.
A sufficiently large series of measurements at a few overflow locations,
representative of different land uses or degrees of imperviousness, can
then be used to synthesize results for the remaining catchments.
When time and budget constraints make an extensive monitoring program
infeasible, estimating procedures may be used to establish representative
concentrations of pollutants of interest. The most direct estimates of
the average runoff concentration, c, may be made from Table 3-3 (previously
presented in Chapter 2). Runoff concentrations of six major pollutants
were monitored for a number of cities with either separate or combined
sewers, and the averages of these concentrations reported for each city
(22). The mean and standard deviation of these site-specific average
concentrations are found in Table 3-3. The standard deviation listed in
Table 3-3 reflects differences between cities and should not be used to
3-35
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TABLE 3-3
SUMMARY OF STORMWATER POLLUTANT CONCENTRATIONS(22)
STORMWATER OVERFLOW CONCENTRATIONS
POLLUTANT ^
BOD5
COD
S.S.
Total Coliforms ^
Total Nitrogen
(as N)
Total Phosphorus
(as P)
SEPARATE
MEAN
27
205
608
3xl05
2.3
0.5
DRAINAGE AREAS ^a
STANDARD
DEVIATION
25
118
616
-
1.4
0.4
^ COMBINED
MEAN
108
284
372
6xl06
9
2.8
AREAS ^0
STANDARD
DEVIATION
36
110 ,
275
-
6
2.9
(a) Summary of 20 cities, storm sewers and unsewered areas
(b) Summary of 25 cities, combined sewer areas
(c) All unites mg/1 except coliforms, MPN/100 ml
(d) Geometric mean
3-36
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estimate v the variation of the pollutant concentrations in the runoff
\f
from different storms in a given study area. It should be used only as
a guide for estimating the mean runoff concentration, c. One may choose
c equal to the mean for the many cities, or for a more conservative
estimate of c, the mean plus one standard deviation. For example, a
value for Total Nitrogen for a combined sewered area may be chosen as
c = 9 mg/1 (as N), or more conservatively as c = 15 mg/1 (as N).
Many attempts have been made to relate stormwater loads to land use as
an alternative or possible refinement to the basis for estimating
runoff quality summarized by Table 3-3. These have been somewhat
.successful, but there is usually a very high average error of estimate
in the prediction; that is, for a given land use pattern, the runoff
quality still varies greatly. Despite this limitation, the ability to
relate runoff pollutant concentrations to land use provides the ability
to predict the magnitude of future runoff load changes due to changes in
land use. A general procedure for predicting runoff quality from land
use and population density, developed on a nationwide basis, is outlined
as follows. This procedure is based on load estimates developed in
reports for the Environmental Protection Agency (15,16). In these
studies, loads were determined as follows:
Ms = a(i,j) . R . PI (PDd) . Y (3-3)
MC = 3(i,j) . R . px (PDd) . Y (3-4)
where:
M = pound of pollutant (j) from land use (i) with separate
O
and unsewered conveyance (Ibs/acre-yr)
M = pound of pollutant (j) from land use (i) with combined
sewer conveyance (Ibs/acre-yr)
(i,j) = constant for pollutant (j) and land use (i) with separate
and unsewered conveyance (Ibs/acre-in)
(i,j) = constant for pollutant (j) and land use (i) with combined
sewer conveyance - (Ibs/acre-in)
R = annual precipitation (in/yr)
I = population function
3-37
-------
PD = population density (persons/acre)
Y = street sweeping effectiveness factor
Equations (3-3) and (3-4) permit an estimate of BOD SS, VS, PO and
N loads as a function of land use, type of sewer system, population
density, and street sweeping frequency.
Table 3-4 shows the land use categories and pollutants.
TABLE 3-4
LAND USE AND POLLUTANTS
Land Uses Pollutants
1=1 Residential 3=1 BODs> Total
i = 2 Commercial 3 = 2 Suspended Solids (SS)
i = 3 Industrial j = 3 Volatile Solids, Total (VS)
i = 4 Other Developed Areas j = 4 Total PO (as PO )
j = 5 Total N (as N)
The runoff load from residential areas will increase with increasing
population density. The population function is shown below.
o R4
for i = 1 (Residential): P1(PD(j) = 0.142 + 0.218 (PDd)u- ^ (3-5)
for i = 2 or 3 (Commercial or Industrial): p (PD.) =1.0 (3-6)
for i = 4 (Other Developed Areas): p (PD,) = 0.142 (3-7)
The intercept for residential areas (0.142) was determined based on data
for open space. The exponent (0.54) is based on the exponent of the
STORM imperviousness equation at a population density of 8 persons per
acre. Lastly, the coefficient (0.218) is based on an average of data
points with PD, ranging from 5 to 15 persons per acre to yield a p.. (PD,)
of 0.895 at 10 persons per acre.
The street sweeping effectiveness factor, y» was derived by making
numerous runs of STORM with varying street sweeping frequencies (15).
The factor is a function of the street sweeping interval, N (days) and
is defined by equation (3-8).
3-38
-------
N
Y = 2^ if 0 ^ Ng ^ 20 days
Y = 1.0 if NS >. 20 days t3'8)
Table 3-5 lists a and g factors that are used in quations (3-3) and
(3-4) for the loading analysis. The methodology thus far presented is for
the determination of yearly stormwater loads. Both estimating procedures
presented in this Chapter require average runoff concentrations. To
provide this Equations (3-3) and (3-4) for the runoff load were converted
to estimate the runoff concentration.
The resulting equations are:
Es = a(i,j) . Px(PDd) . y (3-9)
cc = b(i,j) . Px(PDd) . Y (3-10)
where:
c = concentration of pollutant (j) from land use (i) with
o
separate and unsewered conveyance (mg/1)
c = concentration of pollutant (j) from land use (i) with
combined sewer conveyance (mg/1)
a(i,j) = constant for pollutant (j) and land use (i) with
separate and unsewered conveyance (mg/1)
b(i,j) = constant for pollutant (j) and land use (i) with combined
tt
sewer conveyance (mg/1)
v The factors a and b were determined from the following conversion:
a(i,j) = (a(ij) • F)/Cy(i) (3-11)
b(i,j) = (3(i,j) • F)/Cy(i) (3-12)
where:
F = 4.42, a constant (mg/l)/(lb/acre-in)
C (i)= runoff coefficient for land use (i)
C (i) was estimated from the percent imperviousness generally associated
with each land use, as described in Section 3.4.2.
for i = 1 (Residential) GV(!) = 0.30
for i = 2 (Commercial) C (2) = 0.70
3-39
-------
TABLE 3-5
AND g^ FACTORS'
Pollutant
i=l
i=2
i=3
i=4
i=l
i=2
i=3
i=4
Land Use
Residential (a)
Commerical (a)
Industrial (a)
Other Developed Areas C«)
Residential (B)
Commerical (3)
Industrial CB)
Other Developed Areas (3)
BO
CJ
0.
3.
1.
0.
3.
13.
5.
0.
'D5
=D
799
20
21
113
29
2
00
467
SS
(3=2
16.
22.
29,
2.
67.
91.
120.
11.
)
3
2
1
70
2
8
0
1
VS
9.
14.
14.
2.
38.
57.
59.
10.
3)
45
0
3
6.
9
9
2
8
(
0.
0.
0.
0.
0.
0.
0.
0.
P°4
3=4)
0336
0757
0705
00994
139
312
291
0411
U
0.
0.
0.
0.
0.
1.
1.
0.
N
=5)
\
131
296
277
0605
540
22
14
250
(a)
Applies to separate and unsewered drainage areas
^ ^Applied to combined drainage areas
(c)
Units are Ib/acre-in
3-40
-------
for i = 3 (Industrial) C (3) = 0.60
for i = 4 (Other Developed) C (4) = 0.10
Table 3-6 lists the converted a and b factors that are used in equations
(3-9) and (3-10) for the determination of runoff concentrations. The a
and b factors of Table 3-6 were calculated with the assumed runoff
coefficient for each land use, C (i) and may be adjusted according to
equations (3-11) and (3-12) if it is felt that a different runoff
coefficient is appropriate for the particular land use in the given
study area.
To illustrate the use of this methodology, assume that an area has combined
sewers and portions of the area are residential (with PD, = 20), commercial,
and industrial. If the street sweeping interval is greater than 20 days,
the BOD pollutant concentration for each area may be calculated as follows:
n ^4
Residential: pjCPDj) = 0.142 + 0.218 (20)
Pl(PDd) =1.24
c = (48.6) . (1.24) = 60.3 mg/1 BOD
L* ' O
Commercial:~ c = 83.2 . (1) = 83.2 mg/1 BOD
C 3
Industrial: c = 36.7 . (1) = 36.7 mg/1 BOD,.
C o
Other: c = 20.6 . (.142) =2.9 mg/1 BOD,.
C 3
The concentration calculated for each land use category may then be
assigned to the corresponding runoff flow from that area.
Note that the values obtained from this methodology represent averages
of widely scattered data, and one should not be surprised if the actual
monitored runoff concentrations for a particular area differ noticeably
from those calculated. The concentrations calculated with the EPA
land use-population density approach differ from the results summarized
in Table 3-3. For example, in the land use approach all combined sewer v
concentrations are assumed to be 4.12 times greater than the separate
sewer concentrations, while Table 3-3 indicates higher SS concentrations
in separate sewer areas.
3-41
-------
1=1
1=2
1=3
i=4
1=1
i=2
1=3
i=4
a^ AND b(b-
Land Use
Residential (a)
Commerical (a)
Industrial (a)
Other Developed Areas (a)
Residential (b)
Commerical (b)
Industrial (b)
Other Developed Areas (b)
TABLE 3-6
1 FACTORS ^
C (i)
vv •*
0.
0.
0.
0.
0.
0.
0.
0.
30
70
60
10
30
70
60
10
FOR GIVEN Cv(i)
Pollutant
BOD5
iJzli
11.8
20.
8.
5.
48.
83.
36.
20.
2
9
0
6
2
7
6
SS
240
140
214
119
989
578
883
492
VS
139
88
105
115
574
364
434
473
P04
0.50
0
0
0
2
1
2
1
.48
.52
.44
.04
.97
.14
.81
N
1.9
1.
2.
2.
8.
7.
8.
11.
9
0
7
0
7
4
0
fa")
v Applies to separate and unsewered drainage areas
^ ^
Applied to combined drainage areas
Units are mg/1
3-42
-------
The method presented for relating runoff concentrations to land use and
drainage basin characteristics was developed with correlations to
nationwide data. These estimates may be further refined with local
runoff quality data. Regression technqiues have been used to relate
runoff concentrations to local land use characteristics and storm
parameters with varying degrees of success (29,30,31). Note that unless
statistically significant correlations are obtained, regression equations
will provide no more accuracy than the simpler techniques presented.
The estimations thus far introduced are for the mean runoff concentration,
c. The other value of interest is the variation of the runoff
concentration (between storms), v . Preliminary analyses have indicated
v ranging from 0.50 to 1.00. For an initial estimation, a conservative
value of v =1.00 may be selected (22). ,
Once representative estimates of the runoff coefficient and the pollutant
concentrations have been determined, the storm loading assessment may
proceed. Two particular approaches, a statistical method and a simulator
method will now be presented.
3.4.3 A Statistical Method for the Assessment of Storm Loads
A simplified statistical approach to stormwater loading problems is
described in this section. The statistical method for the assessment of
runoff and treatment (22) is a flexible tool for the initial analysis of
stormwater loads, their impacts, and alternative control strategies. It
is a methodology, rather than a specific computer model with fixed
inputs, algorithms, and results. The basic statistical attributes of
the rainfall-runoff process are used to provide simple initial estimates
of the quantities pertinent to stormwater assessments. The statistical
method may be applied initially without extensive data requirements and
sophisticated urban runoff models. More complex models may be subsequently
incorporated if more refined estimates are needed.
The statistical method begins with an analysis of rainfall, the basic
driving force in the generation of stormwater loads. Raingage data is
analyzed to provide a statistical summary of the rainfall process. The
3-43
-------
characteristics of the drainage area are then used to determine the
runoff flow and associated pollutant load. This load may be modified by
treatment or storage; either by the existing conveyance system, or by
special stormwater control facilities. The stormwater loads thus developed
are subsequently applied to the receiving water to determine the severity
of their impacts (Chapter 5).
Initial storm load assessments require a broad summary of the rainfall-
runoff process. The statistical method performs this summary by
determining the statistical properties of the relevant storm
characteristics. The simulator method presented in Section 3.4.4 operates
directly on the actual rainfall record to perform the assessment. Both
methods determine the expected frequency of various storm load magnitudes.
If the probability distribution functions of the storm characteristics
are well represented by the theory of the statistical method, the results
of the statistical and simulator methods will be similar. The statistical
method provides a more general initial summary,.while the simulator
method allows for more specific analyses of temporal and spatial detail.
The statistical method is outlined in Figure 3-10, and specific procedures
for employing the methodology will now be presented.
3.4.3.1 Statistical Rainfall Characterization
Hourly rainfall data is obtained for a minimum of five years of record
to provide sufficient confidence in the rainfall characterization.
Longer term records covering many years are preferable and are usually
available for U.S. Weather Bureau Stations.
The hourly data are then summarized into storm events, each with an
associated unit volume (v, in), duration (d, hr), average intensity
(i = v/d, in/hr), and time since the previous storm (6, hr), measured
from the midpoint of the successive storms. A storm definition must be
established to determine when in the hourly record a storm begins and
ends. Additional refinements may be added to include such things as
snowfall, trace storms, or whatever appears appropriate for the study
area (22). A computer program is available which reads hourly rainfall
records, defines the end of a storm by a fixed number of consecutive
3-44
-------
I
•f*
Ul
Inputs
Rain Gage Data (Hourly)
a) U.S. Weather Bureau
b) Local Gages
a) Monitored Runoff Data
or
b) Land Use Data
c) Population Density
d) Rain Gage Density
"a)Monitored Quality Data
or
b) Land Use
c) Combined or Separate Sewers
Treatment Specifications:
b) Storage Capacity
c) Concentration Reduction
Receiving Water Characteristics:
a) Advection
b) Dispersion
c) Reaction
d) Background Concentrations
vo re:
<0> DEFER TO CHAPTER 9.
\
Procedure
I. STATISTICAL
RAINFALL
CHARACTERIZATION
II. DETERMINE RUNOFF
IV. MODIFY LOADS
V. RECEIVING WATER1"1
QUALITY IMPACT
ANALYSIS
Results
Mean and Variation of:
a) Storm Intensity
b) Duration
c) Volume
d) Time Interval Between Storms ^X
Mean and Variation of:
a) Runoff Coefficient
b) Resultant Runoff Volumes
and Flows _/
^ ,
Mean and Variation of:
b) Resultant Runoff Loads
and Loading Rates J
1 t
Mean and Variation of:
and Loading Rates __^/
i*"
Mean and Variation of:
a) Transient Pollutant Concentrations
(During Storms)
b) Long Term Pollutant Concentrations
c) Resultant Violations of Standards^/
FIGURE 3-10
STATISTICAL METHOD FOR THE ASSESSMENT OF R-JNOFF
-------
hours without precipitation, includes all forms of precipitation and
determines the relevant individual storm characteristics. This program
is outlined in Appendix E which will be included in this manual at a
later date.
The statistics of the storm parameters are then computed. The mean and
the coefficient of variation of each parameter are determined: the mean
is the arithmetic average; the coefficient of variation is defined as
the standard deviation divided by the mean. The required statistics are
summarized below.
Coefficient of
Parameter For Each Storm Mean Variation
Storm Intensity i I v.
Duration d . D v
d
Unit Volume v V v
v
Time Between Storms 6 A v
Note that if storm intensities and durations are independent, the mean
storm volume, V, will equal ID. In many areas, they are not independent;
for example, long less-intense storms tend to occur in the winter, and
short more-intense storms tend to occur in the summer. In such cases,
V will not equal ID. To avoid this potential error, the rainfall analysis
program determines V for the individual storm volumes. If a particular
season or period is considered critical due to adverse receiving water
characteristics or greater pollutant accumulation rates, the representative
summary may simply be made on the long term record of storms occurring
during the selected season. The rainfall analysis program described in
Appendix E provides monthly summaries which can be used to indicate and
analyze seasonal characteristics.
Once the mean and the coefficient of variation of the rainfall
characteristics have been determined, the cumulative density function
may be developed. This is done by assuming that the rainfall parameters,
storm intensity, i, duration, d, and time between storms, 6, are gamma
distributed. Storm volume, v, would then have a distribution determined
by the product of two gamma distributed random variables (i and d).
3-46
-------
In practice, storm volumes have also been found to be fairly well
represented by a gamma distribution.
The cumulative density function for a gamma distribution is shown in
Figure 3-11. A number of graphs have been used because of the confusing
manner in which the curves intersect. For example, if the variation of
storm intensities determined from the statistical rainfall analysis is:
v. = 1.00, from Figure 3-11(a) the 90th percentile intensity would then
be 2.3 times the mean intensity, I. In other words, ten percent of
the storms have average intensities greater than 2.3(1). Interpolation
may be used for intermediate values of variation.
The expected number of storms greater than a given value may then be
calculated. The average number of storms occuring during a given period
is first calculated:
Average number of storms = Length^of Period (3_13)
Then, for example, if the period of interest is one year and the
statistical analysis indicates that the average time between storms, A, is
70 hours:
Average Number of Storms . l P*"^ g60 hr/year = 125
The expected number of storms greater than a given value is then the
fraction of storms greater than the given value times the average number
of storms. From the previous example, there will be (on the average)
(0.10) . 125 = 12.5 storms per year with average intensities greater
than 2.3(1).
3.4.3.2 Determination of Runoff
The rainfall parameters are next converted into runoff. The approach
for initial assessments uses the average volumetric runoff coefficient,
C . The runoff coefficient indicates the fraction of the storm volume
which reaches the conveyance system:
VR = 3630 . CyVA (3-14)
3-47
-------
I
*>
OO
99
98
97
95
94
93
92
91
90
80
s 70
5
5: eo
50
40
30
20
10
V 10.90
*• 0.75
§
01234
MULTIPLES OF THE MEAN
99
98
97
96
95
94
93
92
91
90
80
70
60
50
40
30
20
10
0
Vtl.OO
I
234
MULTIPLES OF THE MEAN
FIGURE 3-11 (a)
CUMULATIVE DENSITY FUNCTION FOR
GAMMA DISTRIBUTION
-------
2345
MULTIPLES OF THE MEAN
34567
MULTIPLES OF THE MEAN
10
FIGURE 3-ll(b)
CUMULATIVE DENSITY FUNCTION FOR GAMMA DISTRIBUTION
-------
where:
VD = mean runoff volume (ft3)
K
V = mean unit rainfall volume (in)
A = drainage area (acres)
3630 = conversion factor to make units consistent (ft /acre-in).
The runoff coefficient may also be used to estimate the flow rate:
QR = CVIA "(3-15)
where:
QR = mean runoff flow (cfs)
I = mean rainfall intensity (in/hr).
Depending upon the size and characteristics of the drainage basin, this
may not acurately represent the attenuation of runoff beyond the end of
a rain event. The value of Q will be overestimated for a large catchment
K
area with a long time of concentration (the time it takes runoff from
the farthest portion of the drainage area to reach a particular point in
the receiving water). The estimate of Q_ may be tood conservative even
~" K
for an initial assessment. Unit hydrograph analysis (32) may provide
guidance for evaluating or correcting the overestimation of Q . In some
K
cases, however, more sophisticated models employing the time routing of
flows may l>e required.
The best way to determine the runoff coefficient for a particular study
area is to compare raingage data with the runoff monitored during
corresponding storms. Sufficient data of this type is often not available,
and in such cases estimates must be made based upon land use
characteristics, either from land use surveys of the drainage area, or
inferred from the population density. Procedures for estimating the
average runoff coefficient, Cv, are presented in Section 3.4.2.1..
The fraction of the storm volume that is measured as runoff is not
fixed. There is some variation in the runoff coefficient due to
differences in soil moisture, soil infiltration rates or the available
depression storage due to the influence of individual storm conditions
and the length of time since the previous storm. There is also a variation
3-50
-------
in the measure of the runoff coefficient resulting from the variation
from storm to storm in the amount of rainfall recorded at a point
(raingage) versus the amount that actually falls over the entire catchment
area.
Studies dealing with the relationship between point rainfall data and the
areal distribution of rainfall (33-38) indicate that for many areas,
point rain data will be representative of very large areas, when evaluated
on a long term basis (e.g. annual rainfall volume). Characterizing
runoff during individual storm events from a large drainage area with a
limited number of raingages, however, is a separate consideration.
Significant variation in the measured runoff coefficient has been observed.
Studies are now underway (22) to quantify a relationship between the
raingage density, the type of storm patterns typical for an area, and
the variation in the runoff coefficient. Preliminary results suggest
that the variation in volumetric runoff coefficient can become substantial
if the raingage density is less than one per square mile (22). When
completed, the information gained from these studies will permit the
variation of the runoff coefficient to be incorporated into the estimate
of the variation of the runoff volume, v and the variation of the
VR
runoff flow, v • Until then, the estimate of runoff variation may be
based solely upon the variation of the measured rainfall parameters:
vvR = vy (3-16)
vq = v± (3-17)
Runoff flows and volumes have also been observed to be well represented
by a gamma distribution. The cumulative density functions of Figure 3-11
may then be used to predict the fraction of storms and the expected
number of times per year, month, or season that a given flow or volume
is exceeded.
3.4.3.3 Determination of Loads
Runoff flows may be translated into stormwater loads by multiplying the
runoff flows by the appropriate pollutant concentration, c (mg/i). if
storm runoff flows and concentrations are independent, the mean runoff
3-51
-------
loading rate, (W Ibs/day), will simply equal the product of the mean
concentration, (c, mg/1), and the mean runoff flow, (Q_, cfs).
K
WR = 5.4 . c" QR (3-18)
It is best to begin by assuming c and Q are independent. If data
collected for specific pollutants indicates they are not, the following
refinement may be employed:
WR = 5.4 . 5QR (1 + vcvqPcq) (3-19)
where:
v£ = the variation of the pollutant concentration (between
storms)
v = the. variation of the runoff flow (between storms)
"
P = the linear correlation coefficient between the pollutant
concentration and the storm runoff flow (ranging from -1
to +1)
Positive correlation between the pollutant concentration and the storm
runoff flow will yield a higher average loading rate, while negative
correlation will yield a lower average loading rate. Note that the
correlation between flow and concentration is not the first flush effect,
which relates the concentration within storms to the time or volume
since the beginning of the storm (to be dealt with in the section on
storage/treatment in Chapter 6). The correlation dealt with here relates
to storm event averages of the flow and concentration. Procedures for
estimating pollutant concentrations in stormwater are presented in
Section 3.4.2.2.
The variation of the runoff loading rate is due to the variation of the
concentration and the flow. Assuming the flow and concentration are
independent, the variation of the runoff loading rate, v , may be
determined as follows:
v = v v /I + 1/v 2 + 1/v 2 (3-20)
wqcv q c
The calculation of the variation of the runoff loading rate, v , when
flow and concentration are not independent has 'not yet been fully
3-52
-------
developed. Until the method (22) for determining the variation of the
runoff loading rate, v , is developed for the case where flows and
concentrations are not independent, the assumption that flows and
concentrations are independent must be made, and Equation (3-20) used
for a first estimate.
The actual cumulative density function for storm loading rates has not
yet been determined. It is formed by the product of two gamma distributed
random variables (c and q). As a first estimate, the loading rate is
assumed to be gamma distributed as well, as is the case when a constant
"typical''1 value is assigned to the runoff concentration. The cumulative
density function of Figure 3-11 may again be used to predict the fraction
of storms and the expected number of times per year, month, or season
that a given storm loading rate is exceeded, as outlined in the section
on rainfall characterization.
The average loading rate, W is representative of stormwater loads
R
during storm periods. The long term average mass discharge rate, W , is
calculated by determining the total storm load during the year (pounds),
and assuming that it occurs continuously (during both rain and non-rain
periods). If the period of interest is a particular month or season,
rather than the entire year, W may be calculated by determining the
total storm load during the particular month or season, and by assuming
that the storm load occurs continuously. W may also be calculated from
the storm statistics for the year, month, or season of interest as
follows:
WQ = WR D/A (3-21)
where:
D = average storm duration (hr)
A = average time between storms (hr)
W is the loading rate which is used to assess the cumulative long term
stormwater effects and may be compared with the continuous municipal and
industrial point source loadings to determine the relative magnitude of
each source. As suggested in Section 3.4.3.1, at least five years of
raingage data, either for the entire year, or during the particular
3-53
-------
month or season of interest, should be used to provide adequate confidence
in W .
o
For pollutants which impact the receiving water in a transient fashion,
such as coliforms or BOD_, the long term loading rate, W , may not fully
^ . O
indicate the severity of the problem. For example, stormwater loads may
contribute only a small part of the total yearly BOD load entering a
O
receiving water in a particular area, but the occurrance of this load only
during storm periods may lead to violations of dissolved oxygen standards
during or immediately following a number of rain events. It is for
such cases that the actual mean loading rate during storms, W and the
K
variation, v , become the important indicators of stormwater loadings.
The relative impact of long term and transient storm loads on receiving
water quality is discussed in Chapter 5.
3.4.3.4 Modification of Loads by Existing System
Stormwater loads may be reduced by employing end of pipe control
techniques, including interception and storage for eventual treatment
(to be analyzed in detail in Chapter 6). Control measures may also
include management practices, such as street sweeping. Where appropriate,
the effect of these practices can be incorporated in the determination
of the mean runoff concentration, c, as discussed in Section 3.4.2.2.
If existing systems already contain some level of treatment or control,
this must be incorporated in the determination of current stormwater
loads. For urban areas with combined sewer systems, the interceptor
will prevent a portion of the runoff from reaching receiving waters as
storm overflows. A basis is available with the statistical methodology for
analyzing the effect of combined s'ewer interceptors which have a capacity
,in excess of dry weather flows (DWF).
The conveyance system may be characterized by an excess interceptor
capacity, QT, which is the available capacity'in the interceptor for
stormwater runoff. In a combined sewer system, QT is the total capacity
minus the dry weather flow (determined by regulator operation). The
fraction of the long term runoff load, f-., which is captured by an
interceptor with excess capacity, Q , has been calculated and is shown
3-54
-------
in Figure 3-12. The performance is a function of the ratio of the
excess capacity to the mean runoff flow, Q , and the variation of the
K
runoff flow, v . Note that the greater the variation in runoff flow,
the more poorly the interceptor will perform on average. The reduction
of the long term runoff load corresponds to a reduction in the mean
runoff loading rate, W for storm events. The fraction not captured is
K
fT = W/Wn (where W is the load bypassed or overflowed).
JL K
Conveyance systems also provide a degree of in-system storage, Vn, both
jj
in the pipe themselves and due to the layout of diversion structures.
The storage capacity effectively retains runoff until the storm subsides,
when the stored stormwater may then be fed to the treatment system or
directly to the stream. The long term performance of a storage device
is a function of the ratio of the effective storage capacity to the mean
runoff volume, Vn, and the variation of the runoff volume, v Note
K VK
that the volume utilized by the dry weather flow should be subtracted
from the total internal storage to determine the effective storage
capacity. The long term performance curves are shown in Figure 3-13.
The fraction of the load not captured is £. = W/WR. These curves were
drawn assuming there is no first flush effect. When a first flush
effect does exist, a disproportionately high fraction of the runoff load
will be captured by the storage device. The improvement in long term
storage device performance due to the first flush effect is depicted in
Figure 3-14. When the first flush exists, Figure 3-14 may be used to
redraw the performance curve obtained from Figure 3-13, with the
corresponding new values of f . The fraction of the load not captured
by the combined effect of interception and storage, f „, may be
approximated by the product of the individual fractions not captured:
fIV = £IfV
Assuming that the load captured by the conveyance system receives treatment
such that there is a fractional removal, r, the resultant mean runoff
loading rate, W *, will be:
' V = fIVWR + (1-fiv) V1-30 C
3-55
-------
o:
EXCESS INTERCEPTOR CAPACITY
MEAN RUNOFF FLOW I
FIGURE 3-12
DETERMINATION OF LONG TERM INTERCEPTOR PERFORMANCE
3-56
-------
0.5 J.O
1.5 2.O 2.5 3.0 3.5 40
EFFECTIVE STORAGE CAPACITY
MEAN RUNOFF VOLUME
4.5
5.0
FIGURE 3-13
DETERMINATION OF LONG TERM STORAGE DEVICE PERFORMANCE
3-57
-------
10
OS
0.7
Q.6
Q5
O.4
0.3
02.
O.I
UASNITUDE OF flRST FLUSH EFFECT:
NONE •
SHALL
MODERATE •
LARGE•
0.1
Q2
0.3
0.4
0.5
0.6
0.7
OB
0.9
1.0
/„ (NO FIRST FLUSH)
VFRACTION OF LOAD NOT CAPTURED]
\jfASSUME NO FIRST FLUSH EFFECT)\
FIGURE 3-14
IMPROVEMENT IN LONG TERM STORAGE DEVICE PERFOMANCE
DUE TO FIRST FLUSH EFFECT
3-58
-------
In a combined sewer system, r would represent the treatment received at
the municipal treatment plant. The curves relating the impact of
interception and storage on the variation of the runoff load are currently
being developed (22).
3.4.3.5 Receiving Water Quality Impact Analysis
Once the stormwater loads have been determined, they are applied to the
receiving water. The statistical nature of the resulting loads, together
with the receiving water characteristics, determine the statistical
properties of pollutant concentrations in the receiving water. Factors
such as advection, dispersion, reaction, and background concentrations
in the receiving water will determine the resulting water quality impact.
Statistical analyses may be necessary for both transient and long term
concentrations. Methods for performing these analyses will be presented
in Chapter 5. The final output of the methodology is the predicted
frequency with which relevent water quality standards and guidelines are
violated.
3.4.3.6 Example Application of the Statistical Method
To illustrate the use of the statistical method, an example will be
presented for a hypothetical drainage area, using rainfall records from
the City of Denver, Colorado.
Statistical Rainfall Characterization
Twenty-five years (1949 through 1973) of hourly rainfall data for U.S.
Weather Bureau Station 052220 were analyzed. The resulting storm
statistics were calculated for each month and are shown in Figure 3-15.
Seasonal patterns are evident in the data, with shorter, more frequent
and more intense storms occurring in the summer. Assuming that critical
water quality conditions occur during the summer, from June through
September, the relevant storm characteristics should be taken from this
period. These are summarized below.
3-59
-------
MEAN VARIATION
.060
tE
X
2 .040
H
.020
0
_STORM INTENSITY*
%
- ' .
, •
- • •
. • »
i 1 i 1 1 t 1 1 1 i i -1 .
123456789 10 II 12
1.50
_, 1.00
0.50
0
MONTH
^ ^ ** *""">
8.0'
6.0
2?
5 4.0
o
2.0
0
DURATION
- • • - * .
• . ,
•
»
*
t i t t I i 1 I t 1 1 1
1 2 3 4 5 6 7 8 9 10 II 12
1.50
•o 1.00
•^
.50
0
• - - - - MONTH
n * f, 9 Kn
0.40
030
!§ 0.20
>
0.10
0
VOLUME
-
• .
* * •
1 1 1 1 ' 1 ! 1 1 1 1 1 1
1 2 3 4 5 6 7 8 9 10 II 12
2.00
J. 1.50
^
1.00
0.50
MONTH
200
ISO
|ioo
50
0
TIME BETWEEN STORMS
-
.
* •
1 I i i I I I 1 l 1 1 1
J 2 3 45 678 9 10 II 12
i-.W
1.50
^ 1.00
0.50
0
. * " •
"
•
"
• • * •
—
i i 1 1 1 t I 1 1 1 1 1
123 45 6789 10 11 12
MONTH
* . .
, • *
— • • * *
-
i I i I 1 1 1 1 1 1 1 1
1 2345 6 7 8 9 10 II 12
MONTH
—
_ . * •
* . « . . •'
i i i i i i i i r i i i
1234 56 78 9 10 II 12
MONTH
"• • • •
' " ' * "
-
1 t 1 1 1 1 I 1 1 1 1 1
J 2 3 4 5 6 7 8 9 10 II 12
MONTH MONTH,
FIGURE 3-15
MONTHLY STATISTICAL RAINFALL CHARACTERIZATION
DENVER, COLORADO
STATION 052220
3-60
-------
APPROXIMATE SUMMER STORM CHARACTERISTICS FOR DENVER
(JUNE THROUGH SEPTEMBER)
Characteristics Mean Variation
Storm Intensity I = 0.055 in/hr v. = 1.55
Duration D = 3.0 hr v = 1.15
Q
Volume V = 0.18 in v = 1.90
Time Between Storms A = 80 hr v. = 1.15
o
Determination of Runoff
The hypothetical drainage area is estimated as 1875 acres with an imper-
viousness of a little over 30 percent. Assume that 70 percent of the area is
served by separate sewers or natural conveyance, and 30 percent is served by
combined sewers. Given this assumption, the separate or unsewered area is
1310 acres, and the combined sewer area is 565 acres. In the example
calculation it is assumed that the percent imperviousness is the same in both
subareas. The runoff coefficient, GV, for both subareas, is estimated
from Figure 3-8, to be 0.35. One should note, however, that the population
density in combined sewered areas is generally greater than that of separate
sewered areas. Thus the percent imperviousness as shown in Equation 3.2 and
consequently the runoff coefficient is usually higher in combined sewered
areas.
The mean runoff flow and volume during summer months is calculated from the
approximate summer storm characteristics, the runoff coefficient, and the
drainage areas.
Separate or Unsewered Area
VD = 3630 . C..VA
K V
3630(ft3/acre-in) : (0.35) . (0.18 in) . (1310 acre)
3 x 105 ft3
% = CVIA
(0.35) . (0.055 in/hr) . (1310 acre) . (1 cfs/(acre-in/hr))
25 cfs
3-61
-------
Combined Sewer Area
VR = 3630 (ft3/acre-in) . (0.35) . (0.18 in) . (565 acre)
1.3 X io5 ft3
QR = (0.35) . (0.055 in/hr) . (565 acre) . (1 c£s/(acre-in/hr))
11 cfs
The variation of the runoff volume and flow in both subareas may be
estimated from the variations calculated for the corresponding rainfall
values:
VvR = vv = ^
vq = v.=1.55
Determination of Loads
For this example, BOD will be used as the variable of interest. From
o
Table 3-3, the BOD concentration of the runoff from the separate and
unsewered area, c , is estimated to be 27 mg/1, and the BOD concentration
S o
of the runoff from the combined sewer area, c , is estimated to be 108
mg/1. The resulting loading rate, WD, during summer storms is calculated
K
as follows:
Separate or Unsewered Area
WR = '5.4 . csQR
(5.4 lb/day/cfs-mg/1) . (27 mg/1) . (25 cfs)
3600 Ib/day BOD5
Combined Sewer Area
WR = 5.4 . ccQR
(5.4 lb/day/cfs-mg/1) . (108 mg/1) . (11 cfs)
6400 Ib/day BOD5
The variation of the BOD loading rate for each subarea, v , is estimated
using Equation (3-20). The variation of the flows, v , has been estimated
as 1.55, and the variation of the BOD concentration, v , may be
o c
3-62
-------
conservatively estimated as 1.00, because local data is not available.
The calculation of v follows:
w
; = V V /1 + -=7T- + —
w q c/ .. 2
v - v 2
c q
= (1.55) . (1.00) /I
(LOO)2 (1.55)2
= 2.41
The long term summer loading rate, including the non storm periods, will
be:
Separate or Unsewered Area
w~ = WDD/A = C3600 lb/day) . (3.0 hr/80.0 hr) = 135 Ib/day BODC
O K il o
Combined Sewer Area
W = (6400 lb/day) . (3.0 hr/80.0 hr) = 240 lb/day BOD
O O
The total average loading rate from both the separate or unsewered and
combined sewer areas may be calculated by adding the loads from each:
Total Drainage Area (Hypothetical)
WR = (3600 + 6400) = 10,000 lb/day BOD5
W = (135 + 240) = 375 lb/day BOD
O o
The simplified assumption that storm loads are gamma distributed may now
be used to estimate the frequency of occurrence of different loading
rates from the total drainage area. Given that v =2.41, Figure 3-
11(b) indicates the cumulative density function for storm loads in
multiples of the average load, Wn = 10,000 lb/day BOD-. The average
K 5
number of storms per summer will be:
3-63
-------
Average number of storms =
Length of Period
A
- 122 day (June-Sept.) .
80 hr
(24 hr/day)
= 36.6
The number of storms per summer exceeding a given average loading rate
is then the fraction exceeding that rate times the average number of
storms. The calculations for various loading rates are summarized
below:
FREQUENCY OF STORM LOADS FOR HYPOTHETICAL
DRAINAGE AREA
w
(Ib/day
BOD5)
10,000
20,000
30,000
40,000
50,000
W/WR
1.0
2.0
3.0
4.0
5.0
Percent less
than or Equal
to W
79
86
89
92.5
94.5
Fraction
Greater
than W
0.21
0.14
0.11
0.075
0.055
Number of
Storms Per Summer
Greater than W
7.7
5.1
4.0
2.7
2.0
WR = Avg. Summer Runoff Load = 10,000 Ib/day BOD5
Modification of Loads By Existing System
The stormwater loads for the hypothetical drainage area have been calcu-
lated by assuming 70 percent of the area is served by separate or unsewered
conveyances, and 30 percent of the area is served by combined sewers. Exist-
ing separate sewer systems generally convey runoff loads to the receiving
water without modification. The combined sewer load/ however, will be
modified by the interceptor system. Assume that the combined sewer
area interceptors have an excess capacity of 11 cfs, equal to the mean
5 3
runoff flow (QT/QD =1.0), and an internal storage of 0.65 x 10 ft ,
I R
or one half the mean runoff volume (VE/VR =0.50). For Qj/QR of 1.0, and
v of 1.55, Figure 3-12 indicates the fraction not captured by the
3-64
-------
interceptor, fj is 0.53. For VE/VR of 0.50, VVR of 1.90, and a moderate
first flush effect, Figure 3-13 and 3-14 are used to determine the
fraction not captured by storage, f of 0.68. Therefore, the fraction of
runoff not captured due to both interception and storage, f is ,-Q 53-,
(0.68) or 0.36. Assuming the captured runoff is treated with forty
percent removal (r = 0.40), the modified average summer storm load, W *
K
from the combined sewer area is:
Combined Sewer Area
V = £IVWR + (l-'Wrt
(0.36) . (6400) + (0.64) (6400) (0.60)
4760 Ib/day BOD
O
with a long term modified summer mass discharge rate, W *:
W * = 180 Ib/day BOD
o o
Therefore the total modified storm load from the drainage area, including
both the spearate or unsewered area, and the combined sewer area is:
Total Drainage Area
W* = (3600 + 4760) = 8360 Ib/day BOD
K i>
W * = (135 + 180) = 315 Ib/day BOD
O o
As the purpose of this chapter is to demonstrate methods for stormwater
load estimation, example receiving water calculations will not be shown
here, but will appear in Chapter 5.
3.4.4 A Simulation Method for the Assessment of
Storm Loads
In addition to the statistical method, storm loads in urban areas may
also be estimated by the use of simulation techniques. Simulators can
be particularly useful in the examination of storm loads, the problems
they cause, and their control measures, because of the detailed representation
3-65
-------
of the sequence of individual events, both in space and time, which they
provide.
A review of Appendix A will indicate that available simulators represent
a wide range of sophistication and level of detail. Most operate from
an input of hourly rainfall data, and, based on physical characteristics
and properties assigned to the drainage area, they calculate the loads
generated on the same time scale as the rainfall input. The simulators
which can be utilized to the best advantage in the assessment stage in
208 planning, are those which at the sacrifice of detail for individual
storm events, are able to process relatively long periods of rainfall
records and thus simulate a broad range of individual events.
A simulator which is considered to be particularly suitable for use in
assessment studies is described below. The description is intended to
provide information on the basic methodology employed by simulators in
general, and to illustrate how a simulator can be utilized in the
estimation of urban stormwater loads. The model which will be discussed
is a simplified stormwater management simulator, developed by Metcalf
and Eddy and used during a stormwater assessment study for Rochester,
New York (29). It was developed as a screening technique for the planning
and preliminary sizing of control facilities, and is more suitable for
use in assessment studies than the more complex simulators for which it
was substituted. The simulator can be used for the estimation of loads
from combined, separate or unsewered systems.
Use of the simplified stormwater simulator for estimating storm loads
includes the following tasks:
1. Rainfall Characterization
2. Data Preparation
3. Storage - Treatment Balance
4. Overflow-Quality Assessment
These are a series of interrelated tasks that" can be performed either
individually or together, and are composed of small computer programs and
hand computations. The storage-treatment balance is the component which uses
3-66
-------
the computer simulator. The simulator generates a continuous record of over-
flows from a stormwater collection system by reproducing the drainage area
characteristics and calculating responses to rainfall.
The other tasks listed are either required as support for the simulator
(data preparation and overflow-quality assessment) or provide additional
input in the overall stormwa.ter assessment study (rainfall characterization).
It will become apparent in discussing the tasks how each fits into the
assessment.
Rainfall characterization is a part of the approach incorporated into
this simplified simulator to provide insight into the characteristics of
rainfall and therefore runoff, occurring in an area. This characterization
is similar to that employed in the statistical method previously described
in that it characterizes the relative frequency of rain events or ithe
properties of rain events, e.g. duration, total rainfall per storm,
maximum intensity, etc. Examples of frequency curves presented in
Figure 3-16 indicate the number of occurrences per year for storm
volume and storm duration. Procedures for generating these characteristics
from rainfall records are provided in the referenced report (29).
The methodology provided in this report will give information on the
following items: .
1. The total number of storms.
2. The number of storms having a total volume of less than 0.1
inch (approximate depression storage value).
3. The number of storms having durations greater than 24 hours.
4. The average number of days between storms.
The characteristics defined by this rainfall analysis are not used directly
in the simulator, but as background information to aid in the evaluation
and interpretation of results.
Data preparation is an important step in the modeling process. In
addition to rainfall data, information on drainage area and collection
system characteristics must be secured in order to provide the required
input for the operation of .the simplified simulator.
3-67
-------
10
8
La
r u
^ °
^ x
2 w
z a:
5 °
a: a
. UJ
I
0.8
0.6
0.4
0.2
O.I
O.I
I I I I I I II I
25 YEARS OF RECORD
ROCHESTER AIRPORT GAGE
I I I I I III I
I III
0.2
0.4 0.6 I
6 8 10
20
40 6080100
10
8
6
UJ 4
.. Q
CO UJ
S UJ
H UJ
w o:
u. o
0 Q I
O J °'8
H ^ 0.6
rj w 0.4
Q CO
Q
0.2
O.I
O.I
I I I 11 I III
25 YEARS OF RECORD
ROCHESTER AIRPORT GAGE
1 I 1 I I III!
I I I I I II I
0.2 0.4 0.6 I 2 4 6 8 10 20
OCCURRENCES PER YEAR
40 60 80 100
REFERENCE(29)
FIGURE 3-16
FREQUENCY OF STORM OCCURRENCES
3-68
-------
Simplified simulator operation is illustrated conceptually by Figure 3-
17. In the program, rainfall is converted into runoff, by using a K
factor which is a volumetric runoff coefficient similar to the C that
is used in the statistical method presented earlier. The runoff is
stored in a specific storage volume, which represents the volumetric
capacity of the storm and combined sewer system. Runoff which enters
the system is removed by a specific "treatment rate" which represents
the hydraulic capacity of the interceptor downstream of the overflow
point. For combined sewers, both the storage volume and the interceptor
capacity ("treatment rate") used in the simulator are previously calculated
"net" values, which account for volume and flow capacity utilized by dry
weather sanitary sewage flow (DWF). The schematic thus illustrates a
combined sewer system. Separate storm sewer systems or natural conveyances
in unsewered areas would be accomodated simply by equating DWF to zero,
and the interceptor capacity to zero. Thus, the only flow in the system
is storm runoff, and all of it "overflows".
s
When runoff exceeds the storage capacity with a continuous flow greater
than the "treatment flow rate" during the time interval analyzed, an
overflow occurs. The simulator can function on either a daily or hourly
time step. A daily time step is suggested for analysis initially in
order to make analysis of an entire period of record (often 20 years or
more) practical. Examination of this output is used to identify critical
periods for further examination. For specific periods of interest,
including critical storms, the analysis may be performed on the hourly
time step.
The simplified simulator calculates runoff from a drainage area
and the net amount which enters the receiving water.- through
overflows from the collection system. When suitable pollutant
concentations are assigned to the runoff or overflow volumes, storm
generated pollutant loads are calculated as the product of volume and
concentration.
The critical elements which determine the accuracy of the waste loads
calculated by the simulator are the relationships established for:
3-69
-------
CONCEPTUAL
SCHEMATIC
(INTERCEPTOR CAPACITY)
EFFLUENT
REFERENCE (29)
(B)
RAIN
INTERCEPTOR CAR4CITY
("TREATMENT RATE"
OF INTERCEPTOR )„
DRY WEATHER FLOW
(SANITARY SEWAGE)
IN SYSTEM
STORAGE
NON SEWERED
AREA
RUNOFF
\OVERFUOW
FIGURE 3-17
CONCEPT OF STORAGE-TREATMENT PROGRAM
3-70
-------
1. Defining the component of rainfall which will leave the drainage
area as runoff. This is the volumetric runoff coefficient, C ,
(or K, depending on the reference used).
2. Defining the pollutant concentrations associated with the
runoff.
The output from the simulator is a record of the time and volume of
runoff and overflows, and the waste loads associated with them, together
with a summation of these parameters. The summation is terminated at
the end of each year for the daily analysis, and at the end of each
month for the hourly analysis.
The simulator operates on actual rainfall records, and therefore it
internally accounts for the synergistic effect of storms coming close
together with overlapping demands on storage capacities. If the rainfall
record covers many years, then the runoff, overflow volumes and durations
can be filed and ranked, and a statistically significant frequency of
occurence curves can be generated.
3.4.4.1 Example Application of the Simplified Simulator
The simulator can be applied, utilizing a range of levels of spatial
detail. In its simplest form, it would operate on a single aggregated
drainage area in the same manner the statistical method was applied in
the previous example. The addition of spatial detail may be employed
when appropriate, while still utilizing the basic rain-runoff-quality
calculations which are employed at the simplest level.
For the simplest case, use of the simulator would involve the following
steps:
1. Secure rainfall records. They may be analyzed to determine the
statistical properties for aid in evaluating simulator output.
Hourly rainfall data is used in the simulator.
2. Characterize the Drainage Area
a. Determine total area, area served by combined sewers, and
separate and unsewered area.
3-71
-------
b. Determine percent impervious area, using guidelines or
estimating relationships previously presented. >
c. Estimate runoff coefficient (called K factor in this
I
reference), using either available data or basing estimate on
imperviousness. "*
d. Estimate or measure average dry weather sewage flow.
3. Estimate or determine internal storage in sewer system, and a
"typical" interceptor capacity for combined sewers which is
representative of sewers in the area. Separate storm sewers
or natural conveyances would have both internal storage and
"interceptor capacity" set at zero, since all storm runoff
reaching such systems will "overflow". For combined sewers,
net interceptor capcity is established as the difference
between the hydraulic capacity of the sewer line and that part
of the capacity utilized by dry weather flow.
To operate the simulator, each of the above parameters which are
characteristic of the study area are incorporated into the program as
constants. A record of hourly rainfall data is then read as program
input. Output will consist of a tabulation of the runoff and overflow
volumes to the receiving water for the period of record analyzed.
This tabulation may then be summarized, averaged or analyzed statistically
to characterize the volumetric storm overflows.
Storm loads may be determined by assigning a pollutant concentration to
the simulated volumes and calculating a load. In the absence of local
data, relationships previously presented may be employed for estimates of
typical concentrations.
Additional insight into the use of the simulator at any level of spatial
detail will be provided by examination of the subsequent example application.
The example presented below illustrates a more detailed application of
the simplified simulator. It describes the estimation of storm runoff
loads from the Rochester, N.Y. urban area (29), which has both separate
and combined sewer systems.
3-72
-------
System schematic diagrams which show the overflows, drainage areas
associated with the overflows and the pertinent interceptor capacities
for the combined sewers are required to identify the characteristics of
the sewer system and its existing overflow points. An essential first
step in developing these data is to acquire the best and most recent
sewer and storm drainage maps for the region under investigation.
Overflows are defined as any point on the collection and interceptor
system specifically designed to permit excess flows to bypass the routing
to the treatment plant. Some of the important characteristics of the
overflows which should be identified in the system schematic are:
1. Location of the overflows on the interceptor system
2. The hydraulic capacity of the overflows and/or regulating
structures that control the overflows
3. The capacity of any restrictions within the interceptor system
that restrict flow to the overflow
4. The drainage area served by the overflow point.
Drainage areas or subareas are defined by delineating the sewered area
that is tributary to a particular overflow structure (one overflow for
each subarea). These drainage subareas subdivide the entire sewered
area. The signficant characteristics of each drainage subarea are:
1. The total surface area
2. Percent of the subarea that is impervious
3. Percent distribution of the industrial, commercial, and
residential (single-family and multifamily) and other significant
land uses
4. Average slope of the ground
5. Average dry-weather flow.
The interceptor system described in the schematic should include the
following information:
1. The components that connect each subarea to the treatment
plant
2. The maximum capacity of these components
3-73
-------
3. The capacity of components that are particularly restrictive
in the system near an overflow
4. The available in-system storage.
The maximum capacities of the interceptor system are often calculated
using Manning's equation assuming unsurcharged open channel flow. If
the system can surcharge, significantly higher flow rates can occur and
appropriate values for maximum interceptor capacity should be calculated.
In-system storage should be identified where it provides significant
volumes in trunk lines or in interceptors. The effort required to
define both existing and any unrealized potential for in-system storage
is worthwhile, since in some cases storage volume in such existing lines
may be increased dramatically by low cost modifications (e.g. weirs,
dams), and provide a cost effective control technique.
An example of a system schematic prepared 'for the Rochester, New York
study is shown by Figures 3-18, 3-19 and 3-20. These figures illustrate
the sequential development and consolidation of pertinent data utilized
in the operation of the simplified simulator.
On a map of the urban area, all significant overflows are located.
Then, using sewer and storm drainage system maps, the drainage sub-
catchment area which contributes flow to the system at each overflow
point is delineated (Figure 3-18).
A schematic of the collection system is then prepared (Figure 3-19)
which indicates clearly the routing, interconnections and other features
of the system. The location of the input to the system from each of the
sub-areas is shown. The hydraulic capacity of the lines between each of
the sub-area inflow points and each overflow point are determined and
recorded.
Figure 3-20 represents a final condensation of the salient features of
the collection-overflow system. It summarizes and illustrates the
physical and spatial characteristics of the drainage area which will be
structured into the simplified simulator. It defines the routing of the
3-74
-------
SUBAREA BOUNDARY
SUBAREA NUMBER
OVERFLOW NUMBER
OVERFLOW LOCATION
SUBAREA WITH SEPARATE
STORM SEWERS
REFERENCE (29)
FIGURE 3-18
ROCHESTER SUB-DRAIN AGE AREA AND OVERFLOW LOCATIONS
3-75
-------
_ LEGEND:
LAKE ONTARIO S £X 0 SUBAREA NUHBER
A >*" " ~ ^J. *"*"'"^ 51 OVERFLOW NUMBER
CHARLOTTE | 1 , .
PUMPING 1 1 VANLARE
STATION 1 1 TREATMENT PLANT Q MONITORING LOCATION
Dw 'V
FLOW ONLY V.N.
'MAPLEWOOD PARK \
PUMPING STATION
^ (,T
01 \
I (10)
•~o««
2. (184)
21
0(234) ^
(9) ** KX"
O(439) (26 ) — r
WEST SIDE 1 [(SsT
TRUNK 1 n_ \
SEWER u~~ t/^t \
(90)
®(200) |(36)
(123)
(416)
6ENESEE VALLEY .
CANAL SEWER -v.C
©(27)
®(2S)
(200) ' \ (200) 1
\
\\
X
INTERCEPTOR >X >
SEWER Af,
(193) ©
J NORTON- DENSk
SCREENING AND CHLORINAT
(173)
EAST SIDE
(81) TRUNK SEWER
J (116) . (107) (451)
(85) (ze)
1 ^>*\ vt3'
(47)
<409)
X/C (54)
^-O" 2?.
-Ol
©(43)
Ol
L I
' (75) f
11. | '
— O-
NTERCEPTOR
:APACITY, MGD
\
\
«ORE >y
ON STATION |
^DRY
WEATHER
FLOW ONLY4
TYRON PARK
PUMPING
STATION
i 1 5 )
L-^ ~~\
IRONDEQUOITBAY >^
(
C5°)
-rO—
31
>
(291) JL
vso)
RUNOFF
FROM
SUB-AREA
NO. 50
^^ S^. /^*\ f-Ll ELMWOOD AVENUE
18 C20 VL!/ * * PUMPING STATION
REFERENCE (29)
FIGURE 3-19
COLLECTION SYSTEM LAYOUT
3-76
-------
VANLARE
TREATMENT PLANT
0.0 | (100)
_JL
6.8
(9CX7)
LEBEND:
(7T) SUBAREA NUMBER
<=> OVERFLOW
linnl INTERCEPTOR
(ZOO) CAPACITY, M60
n STORAGE VOLUME
MIL GAL
(200)
(aoo)
(75)
REFERENCE (29)
FIGURE 3-20
SUMMARY OF COLLECTION SYSTEM
3-77
-------
storm flows and loads which will be generated for each of the indicated
sub-areas by the load generating methodology employed in the simulator.
Storm loads are generated by the simplified simulator on the basis of
rainfall and the characteristics of each of the sub-catchments. The
significant features of the drainage area are determined, and summarized
as illustrated in Table 3-7. Procedures for developing land use data
bases are described in Appendix C. For the Rochester, New York study
illustrated by this example, aerial photographs supported by field
observations were used to define the distribution of the total area into
the various land use categories. Area determinations were made by
planimeter measurements from maps and photographs. Slopes were determined
by a field survey, and the imperviousness was estimated on the basis of
aerial photographs supported by field observations. The average dry
weather sewage flow (DWF) in the combined sewers was estimated using the
contributing population for each sub-area factored by a per-capita rate
of flow.
Table 3-8 illustrates the procedure used to calculate the available wet
weather capacity of the interceptor system. This is determined for each
limiting segment downstream of an overflow point, as the difference
between (a) hydraulic capacity of the interceptor which is based on
diameter and slope, and (b) the cumulative dry weather sewage flow in
the line at that point.
Figure 3-21 illustrates the results of a statistical analysis performed
on the simulator output for long term rainfall records for the Rochester,
New York example. Both runoff volume, and overflow from the combined
sewer collection system were analyzed and the plot indicates graphically
the estimated amount of total storm runoff retained by the existing
system of interceptors. As a long term average, the data may be
interpreted to indicate that approximately 70 percent of runoff is inter-
cepted and contained by" the existing system. For the larger storm events,
which occur less frequently, this retention efficiency can be expected
to be less than 50 percent. Waste loads would be estimated by assigning
an appropriate concentration, obtained from Section 3.4.2.2, to these
volumes.
3-78
-------
w
TABLE 3-7
EXAMPLE OF DRAINAGE SUBAREA CHARACTERISTICS
Land Use, %
Sub-
area
No.
6(a)
7
8
9
16
17
18
21
22
25
25W(a:)
26
28
29
31
50^
Total
area,
acres
1,277
715
984
2,603
826
235
541
821
569
348
1,390
554
778
1,430
1,592
1,720
fa")
v ^Serviced by
Residential
Single-
family
19.3
83.9
34.5
52.5
50.0
83.8
93.7
79.4
59.8
30.0
50.0
30.0
65.0
65.0
50.0
65.0
separate
Multi-
family
1.3
1.0
2.2
0
9.4
3.8
0.6
0
25.3
9.9
10.0
9.9
10.0
10.0
10.0
20.0
storm sewers
Commer-
cial
1.9
7.3
47.0
4.1
33.8
2.1
3.8
9.0
6.7
44.9
20.0
44.9
10.0
10.0
20.0
5.0
Indus-
trial
65.8
0.2
3.2
37.1
1.1
0
0
6.8
4.9
5.0
10.0
5.2
4.9
5.0
15.0
5.0
Open
11.8
5.5
13.2
6.4
5.7
10.2
2.2
4.9
3.3
10.2
10.0
9.9
10.0
10.0
5.0
5.0
Average
slope,
ft/ft
0.0074
0.0118
0.0066
0.0060
0.0070
0.0067
0.0073
0.0065
0.0070
0.0080
0.0150
0.0100
0.0100
0.0100
0.0100
0.0150
Imper-
vious
Area, %
55.0
50.0
45.0
50.0
55.0
40.0
40.0
35.0
50.0
80.0
35.0
65.0
50.0
55.0
47.0
40.0
DWF
(maximum
avg), MGD
7.06
3.21 ,
6.36
14.00
5.78
1.33
2.60
4.60
3.41
4.50
6.01
5.91
4.36
7.86
10.13
11.90
Reference (29)
-------
TABLE 3-8
EXAMPLE OF CALCULATION OF WET-WEATHER
>LOW CAPACITY, MGD
Subarea
Number
West Side System
17 and 18
25
16
8 and 9
22
21
7
6
East Side System
26
31
28 and 29
DWFW
maximum
average
(1)
3.9
4.5
5.8
20.4
3.4
44.7^
3.2
' 7.0
Sum of
DWF
(2)
3.9
8.4
14.2
34.6
38.0
82.7
85.9
92.9
Maximum
interceptor
capacity
(3)
416
123
47
35
84.7
173.4
10.0
184
Available
wet -weather
capacity
(4)
412.1
114.6
32.8
14.6^
46.7
90.7
6.8^
100.0
5.9
22.0
12.2
5.9
27.9
40.1
(d)
200
200
200
200
^ -^
*• '
= (Average) Dry Weather Flow
The limiting segment is not on the main interceptor
Of this amount, 4.6 MGD is from Subarea 21; 40.1 MGD is from the
East Side trunk sewer
The equivalent of DWF is carried by the east side trunk sewer
Reference (29)
3-80
-------
300
00
LEGEND:
TOTAL RUNOFF
EXISTING OVERFLOW VOLUME
(%) OF RUNOFF CONTAINED BY EXISTING
-(48%) INTERCEPTOR SYSTEM
<7Z%)
I
I
I
I
I
I
I
234 56 78 9 10
FREQUENCY OF OCCURRENCE OF RUNOFF OR OVERFLOW, EVENTS PER YEAR
I i I |
40
0.50 0.40
0.20
0.10
RECURRENCE INTERVAL, YEARS
REFERENCE
FIGURE 3-21
FREQUENCY OF OCCURRENCE OF RUNOFF AND OVERFLOW
-------
3.4.5 Alternate Source Generation and Transport Prediction Methods
Each of the methods to estimate stormwater loads, discussed previously in
this chapter, characterize the concentration of various pollutants in
stormwater runoff. Estimates of- concentration are empirical and are
based on one or more of the following:
1. Collection system type (combined or separate)
2. Land use
3. Rainfall characterisitcs (intensity, duration, interval
between storms).
Appropriate concentrations are assigned to runoff or overflow volumes
for the calculation of storm loads. These stormwater load
characterizations estimate "end-of-pipe" loads which will discharge
either to receiving waters or to control devices. Chapter 5 describes
procedures for estimating water quality impacts in receiving waters for
the storm loads. Chapter 6 describes procedures for assessing the
effect of various control measures on these loads. The characterization
of end-of-pipe storm loads, developed by the methodologies described in
this chapter,provide information in a form which can be utilized directly
in these subsequent analyses.
Other techniques for estimating storm loads have been developed and are
employed in some of the methodologies presented in Appendix A. Instead
of utilizing empirically determined values or relationships for pollutant
concentrations, descriptive models of the mechanisms by which pollutant
loads are generated on land surfaces and transported to receiving waters
are formulated and incorporated into the load estimating procedure.
Figure 3-22 illustrates the characterization of a drainage basin for use
with models which employ source generation and transport. A drainage
area is composed of pervious and impervious surfaces, and a distinct
mechanism of pollutant generation and transport by storms is used for
each land surface type. Sediment and sediment-like material is used as
the indicator for pollutants because it is considered the major constituent
of pollution from the land surface.
3-82
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PERVIOUS AREA
(OPEN SPACE, PARK, LAWNS
. ETC.)/
I EROSION
{UNIVERSAL SOIL LOSS EQUATION I
OR
TIME BETWEEN
STORMS OR STREET
SWEEPINGS
OVERFLOW LOAD= IMPERVIOUS AREA (DIRT AND DUST)+
PERVIOUS AREA (EROSION)
FIGURE 3-22
CHARACTERIZATION OF URBAN STORMWATER LOADS
ACCORDING TO THEIR SOURCE (INSITU) GENERATION
3-83
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It has been stated that the most important contributor of pollutants
observed in urban runoff-overflows is the debris on the land surface
(17,39). This occurs primarily as deposits in streets, gutters and
other impervious areas draining to the street or storm sewers. Pollutants
tend to accumulate on the land surface in many ways. Some of the most
common accumulations occur as debris dropped or scattered by individuals,
sidewalk sweepings, wastes and dirt from construction or renovation,
remnants of household refuse dropped during collection or scattered by
animals or winds, transportation residuals, and the fallout of particulate
matter from the air. Regardless of the way in which pollutants tend to
accumulate on the urban watershed, they can be generally classified into
one of the following categories of street litter: rags, paper, dust and
dirt, vegetation and inorganics. Based on street litter samples taken
during a study in Chicago (17), the most significant category is dust
and dirt except during the fall of the year when vegetation becomes the
dominant component. It has been supposed that nearly all of the pollutants
found in urban runoff can be associated with the dirt and dust component
of street litter. However, the direct link between street dust and dirt
accumulations and urban runoff quality is controversial (40}. Competing
contaminant sources contributing to runoff loads not accounted for by
dirt and dust include:
1. Illicit and cross connections
2. Residuals scoured from pipe and channel networks
3. Neighborhood refuse and refuse management practices
4. Construction and erosion related activities
5. Air carried and deposited pollutants
6. "Natural" background loadings.
In addition, for combined sewer systems, storm overflows would carry
contaminants contributed by raw sewage.
Significant monitoring efforts would be required to calibrate internal
source generation and transport processes, so that they accurately
represent local conditions. It has been suggested that 3 to 5 years of
runoff data would be optimal in order to evaluate.parameters under a
variety of climatic,, soil moisture, seasonal, and water quality conditions
3-84
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(41). This is a significantly higher degree of effort than required in
either the statistical method or the simplified stormwater simulator.
Although estimates or default values are also available for use with
these source generation techniques, they are much less readily checked
and adjusted for local conditions by limited monitoring programs. In
addition, there is a marked scarcity of data for use with these methods
when compared with the amount of data available for the estimation of
pollutant concentrations. For these reasons, methodologies which utilize
source generation and transport mechanisms have not been included in the
procedures recommended in this chapter for the estimation of urban storm
loads. A suitable estimation of loads from non-urban areas, which
provides a more detailed analysis than that outlined in Chapter 2, does
require the use of these techniques. They are accordingly discussed
further in Chapter 4 of this manual which addresses the estimation of
non-urban loads.
3.5 References
1. U.S. Congress, An Act to Amend the Federal Water Pollution Control
Aat3 Public Law 92-500, 92nd Congress, (October 18, 1972).
2. Development Document for Effluent Guidelines and New Source
Performance Standards for the "Textile Mills", US Environmental
Protection Agency, EPA-440/l-74-002-a, June 1974.
3. Development Document for Effluent Guidelines and flew Source
Performance Standards for the "Major Organic Products" Segment of
Organic Chemicals Manufacturing^ US Environmental Protection Agency,
EPA-440/l-74-009-a, April 1974.
4. Development Document for Effluent Guidelines and New Source
Performance Standards for "Inorganic Chemicals Manufacturing"3
Interim Effluent Guidelines3 US Environmental Protection Agency
EPA-440/1-75/037, May 1975.
5. Development Document for Effluent Guidelines and New Source
Performance Standards for the "Unbleached Kraft and Semichemical
Pulp" Segment of Pulp3 Paper and Paperboard Mills3 US Environmental
Protection Agency, EPA-440/l-74-025-a, May 1974.
3-85
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6. Development Document for Interim Final Effluent Limitation Guidelines
and Proposed New Source Performance Standards for "Raw Cane
Sugar Processing", US Environmental Protection Agency, EPA-440/1-75/044,
February 1975.
7. Development Document for Effluent Guidelines and New Sdurce.
Performance Standards for "Dairy Product Processing"., US
Environmental Protection Agency, EPA-440/1-73/021, January 1974.
8. Development Document for Effluent Guidelines and New Source
Performance Standards for the "Red Meat Processing" Segment of the
Meat Product and Rendering Processing., US Environmental Protection
Agency, EPA 440/1-73-012, January 1973.
9. Development Document for Effluent Guidelines and New Source
Performance Standards for the "Poultry" Segment of Meat Product and
Rendering Processing, US Environmental Protection Agency,
EPA 440/1-75/031-b, April 1975.
10. Development Document for Effluent Guidelines and New Source
Performance Standards for the "Citrus, Apple and Potatoes" Segment
of Canned and Preserved Fruits and Vegetables Processing, US
Environmental Protection Agency, EPA 440/1-73/027, November 1973.
11. Development Document for Interim Final Effluent Limitation Guidelines
and Proposed New Source Performance Standards for "Metal Finishing-
Electroplating", US Environmental Protection Agency, EPA-440/1-75/090,
April 1975.
12. Development Document for Interim Final Effluent Limitation Guidelines
and Proposed New Source Performance Standards for the3 "Common and
Precious Metals"3 US Environmental Protection Agency, EPA 440/1-75/042,
April 1975.
13. Development Document for Effluent Guidelines and New Source Performance
Standards for the "Steel Making" Segment of Iron and Steel Industry.,
US Environmental Protection Agency, EPA 440/1-74/024-a, June 1974.
14. Development Document for Effluent Guidelines and New Source Performance
Standards for "Petroleum Refining", US Environmental Protection
Agency, EPA 440/1-74-014-a, April 1974.
3-86
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15. Heany, Huber, Nix, (University of Florida), Storm Water Management
Model, Level I3 Preliminary Screening Procedures, US Environmental
Protection Agency Publication, (At Press 1976).
16. Heany, Huber, Medina, Murphy, Nix, (University of Florida), Nationwide
Evaluation of Combined Sewer Overflows and Urban Stormwater Discharges,
Volume II: Cost Assessment and Impacts, US Environmental Protection
Agency Publication, (At Press 1976).
17. American Public Works Association, Federal Water Pollution Control
Administration, Water Pollution Aspects of Urban Runoff, 11030
DNS 01/69, January 1969.
18. American Public Works Association, Nationwide Evaluation of Combined
Sewer Overflows and Urban Stormwater Discharges, Volume III:
Characterization, US Environmental Protection Agency Publication,
(At Press 1976).
19. Sartor, Boyd, Water Pollution Aspects of Street Surface Contaminants,
Municipal Pollution Control Branch, 11034 FUJ, Environmental Protection
Agency, November 1972.
20. Marsalek, J., Instrumentation For Field Studies of Urban Runoff,
Environmental Management Service, Canada Center for Inland Waters,
Burlington, Ontario, Project 73-3-12.
21. Au, Shane, Hoel, Fundamentals of System Engineering, Probabilistic
Models, Addison-Wesley Publishing Company, Reading, Massachusetts,
1972.
22. Hydroscience, Storm Water Management Model, (In Progress).
23. Graham, Costello, Mallon, "Estimation of Imperviousness and Specific
Curb Length for Forecasting Stormwater Quality and Quantity", Journal
Water Pollution Control Federation, Vol. 46, No. 4, April 1974.
24, Hydrologic Engineering Center, Corps of Engineers, Urban Storm
Water Runoff: STORM, Generalized Computer Program 723-58-L2520,
May 1975.
25. Roesner, et al., A Model For Evaluating Runoff-Quality in Metropolitan
Master Planning, American Society of Civil Engineers, Urban Water
Resources Research Program, Tech. Memo. No 23, April 1974.
3-87
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26. Reiner, Franzini, "Urbanizations Drainage Consequence," Journal
of the Urban Planning and Development Division, American Society
of Civil Engineers, Vol. 1, December 1971.
27. Stankowski, S.J., Magnitude and Frequency of Floods In New Jersey
with Effects of Urbanisation., Special Report 38, US Geological Survey,
Water Resources Division, Trenton, New Jersey, 1974.
28. American Public Works Association and University of Florida,
Evaluation of the Magnitude and Significance of Pollution Loading
From Urban Stormwater Runoff3 Ontario., Department of Environment,
Toronto, 1976.
29. Lager, Didrikson, Otte, (Metcalf and Eddy, Inc.), Development and
Application of a Simplified Stormwater Management Model3 US
Environmental Protection Agency, (At Press, 1976).
30. Colston, Characterisation and Treatment of Urban Land Runoff3
University of North Carolina Water Resources Research Institute,
US Environmental Protection Agency Publication, EPA-670/2-74-096, 1974.
31. Darby, Duvernoy, Management of Urban Watersheds: An Assessment
For Regulatory Action., Allegheny County Health Department and
Carnegie-Mellon University, September 1973.
32. Brater, Sherrill, Rainfall-Runoff Relations on Urban and Rural Areas.,
University of Michigan, Environmental Protection Agency Publication
1975.
33. Court, "Area-Depth Rainfall Formulas", Journal of Geophysical Research,
Vol. 66, No. 6, June 1961.
34. McGuinness, "Accuracy of Estimating Watershed Mean Rainfall",
Journal of Geophysical Research., Vol. 68, No. 16, August 1963.
35. Huff, "Sampling Errors in Measurement of Mean Precipitation",
Journal of Applied Meteorology3 Vol. 9, February 1970.
36. Johanson, Precipitation Network Requirements for Streamflow Estimation.,
Stanford University, Department of Civil Engineering, Technical Report
No. 147, August 1971.
37. Rodriguez-Iturbe, Mejia, "The Design of Rainfall Networks in Time
and Space", Water Resources Research^ Vol. 10, No. 4, August 1974.
3-88
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38. Rodriguex-Iturbe, Mejia, "On the Transformation of Point Rainfall to
Areal Rainfall," Water Resources Research, Vol. 10, No. 4, August 1974.
39. Hydrologic Engineering Center, U.S. Army Corps of Engineers, Urban
Stormxiter Runoff: STORM, August 1975.
40. Field and Lager, "Urban Runoff Pollution Control State-of-the-Art",
Journal of Environmental Engineering Division, American Society
,'of Civil Engineers, Vol. 102, August 1976.
41. Donigan, Crawford, Modeling Non-Point Pollution From the Land
Surface, US Environmental Protection Agency Publication.
3-89
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CHAPTER 4
• ASSESSMENT OF NONURBAN, NONPOINT
POLLUTANT SOURCES AND LOADINGS
4.1 Introduction
Areas requiring comprehensive planning for management of water quality almost
always consist of a series of complex watersheds having a variety of land uses
and hydrologic configurations. In many cases a relatively small percentage of
the total land area is urban with the remaining nonurban areas a mixture of
forested, agricultural, mining, or open lands. Assessment of nonpoint source
pollutants (type and loadings) generated from urban areas was discussed in
Chapter 3 of this manual and included consideration of both intermittent point
sources (stormwater sewers) and diffuse sources (watershed drainage to surface
waters). The following sections are intended to provide guidance in
determining the type and magnitude of pollutants generated from various
nonurban land uses.
Quantitative evaluation of the magnitude and impact of nonurban, nonpoint
source pollutants is currently more art than science. Recently developed
techniques, largely computer simulation models, describing watershed
processes generating stream flow and associated water quality, are briefly
described in Appendix A and will be slightly embellished in a later section
but will not be discussed in detail. Application of any assessment
methodology, simple or complex, should be attempted only with understanding of
the important features of hydrology, soils, sediment transport, and land use.
Equally important are the data bases required to evaluate the problem at
various levels of resolution; The following sections will describe the
general nature of nonpoint pollutant source, types, and loadings; and
discuss the tools available to assess the magnitude and timing of loadings,
and present in detail (with examples) a simplified approach for estimating
loads based on the Universal Soil Loss Equation (1). Finally a
4-1
-------
concise summary of currently available specific information for each non-
point source is presented.
4.2 General Characteristics of Nonpoint Source Loads
Essentially all nonurban, nonpoint source loads enter surface or groundwater
through the overland or subsurface flow paths of the hydrologic cycle.
Notable exceptions include man-made diversions and sewers for highway drainage
or other specific hydraulic structures. NFS problems must be evaluated with
these facts in mind. Stated simply, nonpoint source pollutants result from
the interactions of the hydrologic cycle and land use. Land use and the
associated environmental conditions determine the type, form, concentration,
location, quantity, and time distribution of pollutants within a given
watershed. These factors in turn determine the availability of each pollutant
for transport to surface or groundwater via the hydrologic cycle. Finally,
the energy and space-time distribution of each flow component (surface and
subsurface) determine the amount of available pollutants reaching areas where
water quality impacts are important.
Before numerical estimates of NFS loads are attempted or representative data
presented, two qualitative relationships must be established: (1) the impact
of land use on pollutant type and (2) the impact of the hydrologic cycle on
pollutant transport.
4.2.1 Qualitative Relationship Between Land Use and Potential Pollutants
Land use can be conveniently defined at. two levels for the purpose of relating
man's activities to pollutants. The broad categories of agriculture, forests,
mines, construction sites, waste disposal sites, and hydrologic modification
areas define general land uses from which specific pollutants are emitted.
Each of these land uses may have a wide array of specific activities of
interest. For example, row-crop agriculture undergoes tillage, chemical
application, harvest, and fallow periods during which specific pollutant
loadings may occur.
The quality of water draining nonurban areas is also influenced by watershed
properties that are independent of land use. The geological formations of an
area influence the ionic constituents of both surface and groundwater.
Similarly, untouched "wilderness" areas are subject to the same erosive and
4-2
-------
leaching processes acting on intensively managed areas. Usually, water
coming from these areas is of high quality and need only be considered in
estimating total loads to the system. Exceptions, no doubt, exist so hard
and fast rules cannot be established.
4.2.1.1 Land Use Category - Pollutant Matrix
Most planning areas have ready access to broadly-defined land use data for
initial analysis of NFS problems. For purposes of this manual, land use
categories are defined as follows:
Construction—lands used'for the construction of temporary or permanent
facilities which axe not directly linked to the watershed hydraulic
network (see hydrologic modification).
Agriculture—lands used for production of crops or livestock in areas where
water is supplied by rainfall.
Silviculture—lands used for production of timber or other forest products.
Residuals management lands used for utilization or disposal of waste
residuals from either public of private sources.
Hydrologic modification—lands used as sites for operations which modify
the hydraulic network of the watershed.
Mining—lands used for the extraction of minerals from the earth and for
on-site materials-handling roadway network.
In addition to these categories, others have been defined but have not been
included here. The most notable is irrigated agriculture. The major problem
associated with irrigated agriculture is quality of the return flow. How-
ever, in areas where pollution problems result from the practice of irrigated
agriculture, other nonurban NFS problems are usually of little concern.
Also, management options available for control of return flows are unlike
those proposed for other sources.
The relationship of the above land use categories to potential pollutants is
given in Table 4-1. The noted relationships do not imply that water quality
problems automatically follow - it only shows those pollutants which have a
known potential for becoming a water quality problem as a result of the land
use.
4-3
-------
TABLE 4-1
NONURBAN NONPOINT SOURCE POLLUTION MATRIX
Pollutants
Source
Construction
Agriculture
Silviculture
Residuals
management
Hydro logic
modification
Mining
Sediment
X
X
' X
X
X
X
Nutrients Pesticides
X . X
X X
X X
X
X
X X
Organic
Salinity matter
X
X X
X
X
X
Micro- Trace
organisms metals
X X
X X
X
X X
X
X
-------
4.2.1.2 Land Use Activity - Pollutant Matrix
Within each land use category,an array of human activity can be defined and
presented as a matrix showing relationships between those activities and
their potential for pollution. While a complete review of activity for
each land use would be too lengthy for presentation here, it is useful to
separate each land use category into the next level of resolution. There-
fore, an activity-pollutant matrix for each category is provided for easy
reference.
Construction: Usually, at any one time, only a small percentage of a watershed
is experiencing construction activity. Because many construction activities
are locally intensive, their sites relative to surface waters become very
important, and the pollutant generating potential is best determined by
site-specific analysis. If water quality impacts are to be either monitored
or predicted, however, the scheduling of such activities must anticipate and
reflect the short-term duration of active construction activities. For
purposes of this manual, construction activities are elaborated as follows:
Clearing, grubbing, pest control initial activities associated with site
surveys, equipment and materials transport, removal of undesired
vegetation, etc.
Rough grading—preparation of land surface for location and desired
elevations of planned facilities.
Facility construction—actual construction.
Site restoration—final landscaping, clean-up, excess material removal, etc.
The relationship of these activities to potential pollutants is given in
Table 4-2.
Agriculture: Agriculture is one of the two major land uses in the United
States (forestry is the other). Nationally, over half of the total land
area is classified as agricultural and is grossly divided into cropland,
pastures, and open rangelands. Activity within this land use category in-
cludes the infinite array of operations performed during intense manage-
ment of each agricultural enterprise. The major activities and associated
pollutants resulting from crop and animal production are shown in Table 4-3.
4-5
-------
TABLE 4-2
. SUMMARY OF CONSTRUCTION ACTIVITIES AND ASSOCIATED POLLUTANTS
Pollutant
Sanitary Petroleum Other Metals,
Activity Sediment Nutrients Pesticides wastes products chemicals Trash Cement trace
Clearing,
grubbing, XXX X
pest control
Rough grading X X XX
Facility x x X ' X XXX
construction
olte Y Y Y
restoration
-------
TABLE 4-3
SUMMARY OF AGRICULTURAL ACTIVITIES AND ASSOCIATED POLLUTANTS
Pollutant
Organic Micro-
Activity Sediment Nutrients Pesticides material organisms Salts
Crop Production
Seed bed preparation X
Chemical application XXX
Cultivation X
Harvesting X X
Animal Production
Concentrated feeding XX XXX
Grazing - normal X X
- overgrazing X X
- along streams X XX
-------
These activities remain quite broad and can be divided into considerably more
operations. For example, there are a number of ways to prepare a seedbed
which, in turn, may impact the quantity of pollutants available for movement
by runoff or percolation. The kinds of pollutants should remain essentially
the same, however. A complete discussion of various management systems within
these categories is given in a recently published EPA-USDA report (2).
The common practice of land-spreading animal wastes has been omitted because
it is included in the Residuals Management section.
Silviculture: Silviculture is defined as the cultivation of trees. For
purposes of nonpoint source planning and control (and this manual), the
definition is broadened to include all operations associated with the
production, harvesting, and regeneration of timber. These operations are
defined as follows:
Access those activities required to access standing timber and transport
harvested products (roads and trails).
Harvesting—those activities required to cut, transport, and collect logs for
removal via the access system.
Reforestation—those activities required to prepare sites for reseeding or
species conversion.
Intermediate growing practices—those activities required to control
undesirable species, prevent fires, or otherwise promote growth.
Silvicultural operations are different from agricultural operations in two key
ways: (1) rotations occur over 20 to 60 years, during which many of the above
operations occur only for short time intervals, and (2) during any one time
interval, only a portion of the total forested area is subject to the
activities. These facts tend to mitigate nonpoint source pollutant loads, but
significant problems may exist in some cases.
The relationship of silvicultural activities to potential pollutants is given
in Table 4-4.
4-!8
-------
TABLE 4-4
SUMMARY OF SILVICULTURE ACTIVITIES AND ASSOCIATED POLLUTANTS
Pollutants
Sediments Nutrients
(Organic, (Fertilizers, Thermal
Activity inorganic) fire retardants) Pesticide pollution
Access X
Harvesting X XXX
Reforestation X XX
Intermediate Growing .. ..
Practices
4-9
-------
Residuals Management: Residuals management practices are usually part of a
complete waste management system. However, the primary concern of removing
pollutants from waste streams often fosters neglect of the problems associated
with disposal of the resulting residuals. Residuals include water and waste-
water treatment sludges, septage effluent, municipal refuse, industrial
wastewater treatment sludges, combustion and air pollution control residuals,
dredge spoils, mining spoils, and animal wastes from confined feeding.
General statements about the nature and magnitude of the nonpoint source
problems are difficult because the design and maintenance of each system
varies significantly. For example, the practice of temporary dairy manure
storage followed by land spreading on snow or frozen ground results in
vastly different nonpoint loads than year-round spreading in the warmer areas
of the country. Usually, however, two different problems arise - leaching of
pollutants from buried or injected wastes and runoff or surface applied
or incorporated wastes.
Residuals and their associated potential pollutants are given in Table 4-5.
Hydrologic Modifications: Hydrologic modifications in the truest sense would
include all activities that alter the pathways of the hydrologic cycle. All
construction activities and most other agricultural or silvicultural opera-
tions modify the hydrologic system in some way. For purposes of this manual,
a more narrow definition is proposed: modifications occurring "in-stream" or
"near-stream" such that there are direct links between the activity and water
bodies. These activities include construction of dams and impoundments,
channelization, dredging, and other in-water construction (bridges, docks,
etc.).
The construction phases of hydrologic modifications result in essentially the
same nonpoint source problems as other construction activities. Post-
construction and maintenance may be more significant, however, because of
the direct contact of the facility with the water body. For example, the
impact of boat docking facility construction may be relatively short-term
but subsequent waste oil, refuse, etc., from its use may be a continuous
long-term source of pollutants. .
4-10
-------
TABLE 4-5
SUMMARY OF RESIDUAL WASTES AND ASSOCIATED POLLUTANTS
Activity
Organic Heavy Micro- Suspended Fly
Nutrients material metals organisms TDS solids Alkalinity Acidity ash Other Odors
Wastewater sludge
Septage residual
Water treatment
sludge
Municipal refuse
X
X
X
X
X
X
X
X
X
X
X ' X
X
X • X X X
X
X
Combustion and
air pollution
control residual
Industrial waste
sludge
Feedlot manure
Mining waste
Dredge soil
X
X
X
X
X
X
-------
The major hydrologic modification activities and their potential pollutants
are given in Table 4-6.
Mining: Mining operations in certain regions of the country are the most
significant watershed activity. The current and projected energy and mineral
resource demands suggest a rapid growth of new mining and intensification of
existing activities. The nonpoint source loads can be significant because of
the dramatic change in the landscape and the characteristics of the newly
exposed soils now subjected to erosion and leaching. Above and below ground
mining result in somewhat different problems but both have certain activities
in common that can be conveniently separated by their potential to yield non-
point source pollutants. These activities are shown-in Table 4-7,
Mine drainage is considered the most significant problem. In addition to
sediments transported to streams by runoff, mineral constituents like acids,
heavy metals, nutrients, and radionuclides have been measured in drainage
water. Many of these pollutants result in acute toxicity problems for
receiving waters as well as the common problems of nutrient enrichment,
sedimentation, dissolved oxygen, etc.'
4.2.2 Qualitative Relationship Between the Hydrologic Cycle and
Pollutant Transport
The hydrologic cycle in large part determines the timing,- volume, frequency,
and quality of nonpoint source loadings. The land use activities described
in previous sections determine the location and form of the various pollutants
but any assessment or estimate of actual loadings must be made with proper
recognition of the role of the watershed hydrologic response.
The watershed is best viewed as a system which yields outputs (including
nonpoint source pollutants) in response to a series of inputs. Yevjevich
(3) described this concept nicely when he wrote "Continental surfaces,
underground acquifers, inland bodies of water, plants, and soils are
environments with complex water inputs, environmental compositions, responses,
and outputs. This environmental trinity, input-response-output, in combi-
nations, mutual dependences, and feedbacks is defined as the hydrologic
system." A systems description of agricultural watersheds is given by Stewart,
4-12
-------
TABLE 4-6
SUMMARY OF HYDROLOGIC MODIFICATIONS AND ASSOCIATED POLLUTANTS
Pollutant
Activity
Channel
modification
Impoundments
Dredging
Maintenance
facilities
Organic
Sediment Nutrients Pesticides compounds
X
X X
XX X
X X
Other
chemicals
Trace Thermal (silica,
metals pollution sulfide)
X
XXX
X X
-------
TABLE 4-7
SUMMARY OF MINING ACTIVITIES AND ASSOCIATED POLLUTANTS
Pollutant
I
(-•
4^
Activity
Exploration
Access and support
facility construction
Mineral extraction
Mineral processing
Mine closure
Radio-
Nutrients Sanitary Heavy Acid active
Sediment (fertilizers) Pesticides TDS wastes metals wastes materials
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
et al. (4) which can be generalized to describe any nonurban system.
Figure 4-1 demonstrates the idea.
The nature of the inputs and outputs of the system in Figure 4-1 have
important characteristics that must be understood before a complete assessment
of nonpoint loadings can be made. Indeed, successful NFS control can only be
achieved by knowing where the system is amenable to treatment and the
magnitude and frequency of specific system inputs, properties, and outputs.
Successful monitoring to determine the magnitude of NFS problems or the
effectiveness of in-place controls is also keyed to the factors shown in
Figure 4-1.
Precipitation inputs drive the system and, in large part, determine the total
volume and time-distribution of runoff. In addition to their uncontrollable
nature, precipitation and solar radiation are stochastic and spatially
variable. The impact of these features on calibrating certain rainfall-runoff
models was briefly discussed in Chapter 3. Precipitation measurement via
raingage networks is a well-established science and historical records are
available for many areas of the country. Statistical and mathematical
techniques referred to earlier in Chapter 3 are also available to areally
distribute measured point-rainfall data (5, 6, 7, 8, 9). Significant
quantities of pollutants can enter the watershed via solution-stripping
by precipitation. Typical pollutant types and loadings are given in section
4.2.3.
System inputs classified in Figure 4-1 as controllable are those sub-
stances or activities introduced by man. The land use activities described in
the previous sections summarize these inputs. Location of inputs are variable
but can be part of the controls introduced for reduction of nonpoint source
loads. Indeed, it is only through this set of inputs that water quality
improvements can be made.
As watershed system inputs are transmuted to system outputs, the system
properties described in Figure 4-1 modify their behavior. Some of these
properties, like soil type and topography, are for the most part fixed in both
time and space. Others, like vegetative cover and drainage networks, are
subject to change by the set of controllable inputs. Techniques to measure
4-15
-------
UN CONTROL LABLE INPUTS
PRECIPITATION
la) RAIN
(b) SNOW
SOLAR RADIATION
POLLUTANT RA1NOUT
SYSTEM PROPERTIES
SOILS
TOPOGRAPHY
VEGETATION
DRAINAGE NETWORK
CONTROLLABLE INPUTS
ENERGY
AGRICULTURAL CHEMICALS
WASTE RESIDUALS
LAND USE MANAGEMENT
STRUCTURES
PARTIALLY CONTROLLABLE OUTPUTS
STREAM FLOW
SURFACE RUNOFF SUBSURFACE FLOW
SEDIMENT NITRATES
ORGANIC- N SALTS
AMMONIA-N
PHOSPHORUS
PESTICIDES
PATHOGENS
ORGANICS
METALS
FIGURE 4-1
WATERSHED SYSTEM NON-POINT SOURCE POLLUTANT
LOAD RESPONSE TO HYDROLOGY AND LAND USE
4-16
-------
and specify these properties include interpretation of aerial photos, soils
maps, topographical maps, and other data bases as described in Appendix C.
System outputs are described as partially controllable. This is an important
point to consider when a control program is contemplated. Quantification of
the degree of controlability possible is no trivial task and is directly
related to the uncontrollable and stochastic nature of the system inputs.
Obviously, an absolute standard or goal is impossible to achieve without
violations for certain time periods, however small.
Another important feature of the system outputs of Figure 4-1 is the division
between surface runoff and subsurface flow. The relative distribution of
these flow components varies as a function of surface conditions, watershed
size, and geological formations. In general, as a watershed increases in
size, a greater proportion of the streamflow is determined by subsurface
sources. Estimates of relative magnitudes are important to the correct
interpretation of measured water quality data and the allocation of measured
loads to their respective sources. Some of the NFS models described in
section 4.3.4 are capable of predicting this relative distribution
(10, 11). Other empirical hydrograph analysis techniques for
this purpose are also available as described by Chow (12).
Resolution of watershed drainage into surface runoff or subsurface flow is
important because most pollutants are transported in much greater quantities
in one component of flow than in the other. The outputs shown in Figure 4-1
classify the major pollutants by their major modes of transport. There are,
as always, exceptions to these rules as in those areas where extremely
permeable (e.g., sandy) soil profiles exist or where large areas are
impermeable. NFS controls also must be planned in recognition of flow
distribution b.ecause many candidate practices (e.g., soil conservation
practices) result in a shift in the relative distribution of flows and,
subsequently, a new set of NFS pollutant loads must be analyzed. Interaction
i
of surface and subsurface processes is a major consideration in the decision-
tree analysis for selection of agricultural nonpoint source controls developed
by Stewart et al. (2)
4.-17
-------
The impact of the hydrologic system is important in any attempt to measure
the nature and extent of NFS loads through field sampling. Intensive, con-
tinuous sampling over short periods of time may measure little of the total
extent of the problem. Runoff itself is stochastic as is the time between
runoff events which, in turn, influences the quantity of pollutants available
for transport. Of equal concern are the limitations inherent in grab sampling
over longer periods in that peak loads may be missed entirely. A detailed
presentation of monitoring methods and procedures is given in Appendix D
of this manual.
4.2.3 Representative Nonurban Nonpoint Source Loading Data
Data from studies which attempt to measure nonpoint source loads vary over
several orders of magnitude. This is not at all surprising when viewed
in light of the possible variations in land use activities and the features
of the hydrologic system acting on these activities. Indeed, the wide
variation in data alone should serve as caution against relying heavily on
extrapolation for assessment decisions.
Generally, there are three types of data bases available. They are (1) lysi-
meter or soil column studies, (2) small plot or individual field scale
studies, and (3) drainage basin studies. Interpretation of data from these
studies should be modified by the types of land use they represent, their
location relative to the watershed system depicted in Figure 4-1, and the
time period over which they were developed.
One other nonpoint source - load not included in any of these is precipita-
tion. In areas where surface waters constitute large areas, pollutant
inputs via precipitation can account for a significant portion of the total
load. Typical precipitation loading to land areas is given in Table 4-8.
Each of the three study types represents different components of the water-
shed system. Soil column or lysimeter studies represent only vertical move-
ment of pollutants and effects of surface runoff, groundwater (shallow or
deep) flow, or interflow (subsurface flow returns to surface runoff) are not
included. Small plot or field scale studies represent direct surface runoff
of pollutants and effects of groundwater flow, vertical movement, down-slope
deposition, and different land uses, are not included. Portions of the
4-18
-------
TABLE 4-8
NONPOINT SOURCE POLLUTANT LOADINGS FROM PRECIPITATION*1
Pollutant Range
Type of Loading Total Nitrogen Total Phosphorus Acids, pH
Areal loading 4i4_8>9 0.045-0.055
Ib/ac/yr
Concentration 0>1_12>g 0.005-0.10 4.3-5.6
aSource: (15, 24-29)
4-19
-------
interflow effect may be observed. Drainage area studies include the effects
of all flow components and different land uses. Drainage studies, depending
upon the size of the basin they represent, may also reflect the effects of
stream assimilation capacity. Also, larger drainage basins may be subject
to groundwater export to or import from adjacent basins, making NFS pollutant
mass balance calculations difficult.
Results of typical soil column studies are given in Table 4-9. Extrapolation
of these data to NFS loads would result in overestimation of groundwater
loads, especially for nitrogen. Such studies are very helpful, however,
when investigating the impact of waste residuals, spoil materials, chemicals,
etc., on the soil-plant-water complex. For example, the potential problems
of heavy metal or pathogen leaching from areas (where runoff is controlled)
on which municipal or industrial sludges are spread can be evaluated by
analysis of similar data.
Small plot and field scale (small watershed) studies dominate the literature
available on nonurban, nonpoint source loading. Such studies are very use-
ful because they represent the relative impact of different land uses and
land use activities (including management practices recommended for controls),
and because they provide an estimate of direct surface runoff water quality.
Generally, the larger the area included in the study, the more realistic the
extrapolation of the data because more components of the hydrologic system
are included.
Data from typical studies representing various land uses and pollutants are
included in Tables 4-10 through 4-13. Comparison of the areal contribution
data from these studies with similar data from the soil column studies
illustrate the moderation provided in small watershed studies by the
increased geographical scale and the inclusion of more watershed processes
over those provided by soil column studies.
Data collected during drainage basin studies are usually considered to be
most meaningful in evaluating the water quality impact of nonpoint source
.loads. Two conditions are necessary to make such studies suitable for water
quality impact assessment. First, the measured water quality must be
determined primarily by processes occurring in or on the land surface and
4-20
-------
TABLE 4-9
AGRICULTURAL NONPOINT SOURCE LOADING FROM SOIL COLUMN STUDIES2
Nitrogen yield, lb/ac/yr Phosphorus Yield, Ib/ac/yr
Total
Inorganic
Number
15
28
Mean
25
17
Range
0.3-98
0.3-73
Number
9
6
Mean
1.04
0.47
Range
0.05-6.9
0.01-2.2
Extracted from Chapter 2, Table 2-12
3Number of studies.
4-21
-------
TABLE 4-10
AGRICULTURAL NONPOINT SOURCE LOADING DATA FROM SMALL PLOTS (0.02-0.80 ACRESf
Pollutant Loss, Ib/ac/yr
Crop
Corn
Beans
Soybeans
Wheat
Management: System
Return residue § rye as
cover crop
Return residue § rye as
cover crop
Residue burned, no cover
crop
Residue burned, no cover
crop
No-till
Conventional
Continuous - silage
Continuous corn silage
cover crop
Return residue
Residue removed
Continuous field
cultivator
No-till
Return residue plus rye
grass § alfalfa cover
crop
Return residue plus rye
grass § alfalfa cover
crop
Residue burned, no cover
crop
Residue burned, no cover
N03-N
1.25
0.35
, 2.19
0.35
10.
9.
7.
8.
1.30
26.0
7.
4.
0.83
0.44
1.01
0.53
NH4-N
0.29
0.12
0.88
0.18
K
99
64^
51
37b
0.36
0.44
81b
0.37
1.15
0.32
0.13
Inorganic P
0.115
0.04
0.436
0.14
1.44
0.20
0.48
0.53
0.16
0.33
0.44
1.84
0.15
0.18
0.28
0.07
crop
Meadow
aSource: (27,30)
bContains N0~ + NH*-N.
1.40L
0.43
4-22
-------
TABLE 4-11
TYPICAL PESTICIDE LOADINGS MEASURED ON SMALL PLOTS (44-5700 FT2)'
Pesticide
Aldrin
Atrazine
•
Dicamba
Dichlobenil
Dieldrin
Diuron
2,4-D-Amine
2,4-D-Butylether
2,4-D-[soocryl
Endosulfan
Endrin
Fenac
GS 14254
Linuron
Methoxychlor
Picloram
Prometryne
Toxaphene
Trifluralin
2,4,5-T
Amount
applied
(Ib/ac)
1.3
3.0
1.5
2.7
2.0
4.0
2.0
0.18-1.09
6.0
1.3
0.75
2.0
2.0
2.0
0.9
0.9
0.65
1.3
1.3
0.27
0.36
3.0
2.0
4.0
2.0
22.0
0.5
0.25
0.9-1.8
2.5
24.6
1.25
0.5
10.0
0.9-1.8
Type of
application
SR
Inc. SR
Inc. SR
SR
S
S
SR
SR
Inc. SR
SR
S Ponded
SR
SR
SR
S
S
S
S
S
S .
S
S
S
S
S Ponded
SR
F
S
SR
S
F
Inc.
F
SR
SR
b Crop
Cultivated
Fallow
Fallow
Fallow
Corn
Corn
Corn
Fallow Sod
Fallow
Cultivated
Cotton
Cultivated
Cultivated
Cultivated
Cont. Potatoes
Rot. Potatoes
Oats
Cont. Potatoes
Rot. Potatoes
Sugarcane
Sugarcane
Sugarcane
Alfalfa
Alfalfa
Cotton
Grass
Grass
Range
Fallow Sod
Cotton
Cotton
Cotton ft
Soybeans
Grass
Grass
Fallow Sod
Pesticide loss
in runoff
(Ib/ac)
0.068
0.0741 sediment
0.278 water
0.031 sediment
0.111 water
0.176
0.1
0.19
0.05
0.013
0.117 sediment
0.270 water
0.061
0.0004
0.047
0.7
0.8
0.003
0.002
0.00007
0.012
0.008
0.003
0.001
0.086
0.0004
0,0012
0.0006
0.09
-
0.053
0.013
0.089
0.0005
0.005
0.03
Range of pesticide
loss in runoff
increments
5-138 pg/g
SOO-11,000 pg/1
4-15 pg/g
50-600 ppb
100-10,340 pg/1 water
100-200 pg/1
0.5-10 pg/g
100-3800 pg/1
0.5-4 mg/g
50-2000 pg/1
0-4800 pg/1
4-37 pg/g
100-900 pg/1
1.6-14 pg/g sediment
1-4 pg/1
640 pg/1
1380 pg/1
1.0-19 pg/1
Trace-18 pg/1
Trace-3 pg/1
1.0-49 pg/1
Trace-48 pg/1
<0. 01-2. 07 pg/1
0.15-5.0 pg/1
1-310 pg/1
100-3800 pg/1
0.5-10 pg/g
100-2000 pg/1
0.75-10 pg/1
2-124 pg/1
0.1-8.8 pg/1
349-838 ppb
17 ppb
15-560 pg/1
-60 PE/1
0.2-1.9 pg/1
495-769 ppb
1-380 pg/1
7-3300 pg/1
aSource: f311
bS=Surfacc; Inc.incorporated; F=Foliar; SR=Simulated Rainfall
4-23
-------
TABLE 4-12
AGRICULTURAL NONPOINT SOURCE LOADING DATA FROM SMALL WATERSHEDS
(0.7-150 ACRES)a
Pollutant Loss, Ib/ac/yr
Management
Crop System 3
, Suspended
NH4-N Kjeldahl N P Solids
COD
Corn
Brome
Grass
Pasture
Contour
Contour
Contour
Contour0
Contour6
Contour0
Terraced0
Terraced c
Terraced c
Corn § Oats
rotated
Rotation/-
grazing
Rot at i on/ -
grazing
Rotation/-
grazing
Hay/ grazing
Grazing
1.29
0.47
0.84
2.05
1.30
1.17
0.21
0.13
0.14
0.33
1.02
0.15
0.84
0.21
0.36
0.85
0.31
1.30
1.38
0.37
1.88
0.11
0.03
0.52
-
0.59
0.08
0.38
-
-
2.96
22.46
41.35
5.23
31.02
61.66
0.28
0.46
6.28
0.81
0.46
0.19
2.58
0.65
1.00
0.26
0.52
1.15
0.442
0.923
1.900
0.08
0.018
0.257
0.27 255
0.224
0.072
0.456
0.09 3.6
0.22 10.5
43
12
25
Source: (32,33)
Total loss values represent the inorganic P of the solution and the NaHCO_-
extractable P of the sediment. ,
2.5 times recommended rate applied.
4-24
-------
TABLE 4-13
TYPICAL PESTICIDE LOADINGS MEASURED ON SMALL WATERSHEDS
Pesticide
Atrazine
Dieldrin
•f^
i
N)
Cn
Picloram
Propachlor
Toxaphene
Trifluralin
2,4,5-T
Amount
applied
(Ib/ac)
3.0
5.0
5.0
2.5
6.0
9.0
0.98
2.5
Type of c
application15 Lrop
S
Inc.
Inc.
F
S
F
Inc.
F
Corn
Primarily
Corn
Primarily
Corn
Grass
(Corn Surface)
Cont. Cotton
Cont. Cotton
Grass
Plot
size,
ac
1.7-3.8
1.7
2.7
3.0
1.7-3.8
38.5
38.5
3.0
Pesticide loss
in runott
(Ib/ac)
0.48
0.00035 water
0.11 sediment
0.035
0.00005
0.138
0.0864
0.00176
0.0005
Range of pesticide
loss in runoff
increments
1.77-735 yg/g sediment
1.9-20 yg/1 water
1.6-14 yg/g sediment
0.4-4.1 yg/1
7-12 ppb
117-491 yg/1 water
<10-28 yg/1
7-26 ppb
Source: (31.34)
3S=Surface; Inc. = Incorporated; F = Foliar
-------
not in the stream. In other words, the data should reflect pollutant load-
ings only, rather than a combination of loading and stream processes. (If
all pollutants were conservative this would not be a problem.) Second,
the measured output should be from a "hydrologically closed" watershed. That
is, interbasin transfer of water (and pollutants) should be minimum or at
least measurable.
Ideally, a number of basins having only one land use should be studied.
However, basin studies tend to lump the effects of land use. A recent EPA
study (13) analyzed a number of drainage basins and attempted to correlate
general land use to measured water quality. Results from this and other
studies are summarized in Tables 4-14 and 4-15.
4.3 General Characteristics of Nonpoint Source Load Estimation Methods
The previous section discussed the various kinds of loading data available
and evaluated their usefulness in assessment studies. The importance of
data interpretation within the hydrologic system framework was stressed.
For assessment studies there are various approaches available for estimating
nonurban, nonpoint source loads. The evaluation of these techniques must
also be made within the hydrologic system framework and associated land use
configurations. The following section includes a general discussion of
the basic properties common to most loading methods (models), followed by a
more detailed description of key models now available for application to
assessment studies.
Mathematical modeling of complex phenomena is a rapidly growing science for
which few widely recognized standards or definitions exist. At the risk of
violating the sensibilities of a few modeling practitioners (perhaps even
more than a few), the following definitions are offered:
Empirical methods—calculation procedures based on analysis of data or a
certain known relationship among variables.
Deterministic methods models based on a rigorous representation of known
relationships (physical or mathematical).
Stochastic methods—models based on the concepts of probability theory and
the idea that future events are determined by random processes.
4-26
-------
TABLE 4-14
GEOLOGIC CLASSIFICATION AND MEAN VALUES FOR STREAM NUTRIENT CONCENTRATIONS AND EXPORTS
,a
Land use
Forest
Mostly Forest
I
Is)
Agriculture
FROM 223 SUBDRAINAGE AREAS IN THE EASTERN UNITED STATES
Geologic classification subdrainage
and grouping code(s) areas
Concentrations, mg/1
Export, kg/km /yr
Sedimentary; some or all limestone (10)
Sedimentary; without limestone (20)
Sedimentary; all (10, 20)
Predominantly sedimentary (10, 14, 20)
Igneous; volcanic origin (30)
Metamorphic (40)
Igneous; plutonic origin (50)
Igneous and metamorphic (40, 45)
Predominantly igneous and metamorphic (40,
41, 42, 45)
Sedimentary; some or all limestone (10)
Sedimentary; without limestone (20)
Sedimentary; all (10, 20)
Predominantly sedimentary (10, 14, 20, 23,
24, 25)
Igneous; volcanic origin (30)
Igneous; volcanic origin (Present but not
dominant) (23, 43)
Metamorphic (40)
Igneous; plutonic origin (50)
Predominantly igneous; plutonic origin (50,
52, 54)
Igneous and metamorphic (40, 43, 45, 50,
54) '
Predominantly igneous and metamorphic (40,
41, 42, 43, 45, 50, 52, 54)
Sedimentary; some or all limestone (10)
Sedimentary; without limestone (20)
Sedimentary; all (10, 20)
53
11
30
31
0
16
0
18
22
170
~5T
48
103
118
0
4
32
1
40
52
91
91
T-P
0.011
0.014
0.012
0.012
0.017
0.017
0.016
0.037
0.035
0.036
0.036
0.038
0.035
0.026
0.032
0.036
0.035
0.136
0.123
0.135
0-P
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
006
007
006
006
007
007
007
015
014
014
014
018
014
010
013
014
014
059
055
058
T-N
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
0
4
3
4
.860
.766
.825
.818
.520
.533
.625
.056
.817
.945
.930
.975
.762
.951
.049
.798
.827
.315
.497
.225
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
2
3
I-N
.287
.337
.306
.302
.103
.119
.135
.488
.288
.395
.374
.328
.277
.138
.317
.269
.284
.296
.335
.190
T-P
6.4
9.0
7.4
7.3
10.3
10.3
9.7
16.3
18.0
17.1
17.1
13.1
20.7
7.4
13.6
19.2
18.2
30.5
23.6
29.7
0-P
3.6
4.5
3.9
3.9
4.6
4.6
4.3
6.3
.6.9
6.5
6.2
8.2
2.8
9.1
8.2
8.1
12.4
10.3
12.2
T-N
498
467
487
482
337
342
380
472
441
458
456
332
452
269
476
427
433
996
865
982
.7
.6
.3
.3
.4
.1
.7
.1
.8
.0
.5
.2
.0
.5
.2
.7
.1
.8
.4
.3
I-N
159.6
192.2
171.5
169.1
65.2
74.6
80.7
233.2
161.2
194.3
186.7
115.5
166.0
39.1
134.6
149.8
152.3
748.3
660.1
738.6
Abbreviations: T-P = Total Phosphorus; 0-P = Orthophosphorus ; T-N = Total Nitrogen; I-N = Inorganic Nitrogen
aSource: (13)
-------
TABLE 4-15
RUNOFF AREAL LOADING RATE - POUNDS/SQUARE MILE/DAYa
(Average Range)
Land Use
Agriculture
Forest
Pasture
Feedlots
Total
Nitrogen
15
(1.9-58)
4
(1.3-16)
8
(3.9-13.3)
1700
(1080-2290)
Total
Phosphorus
1.0
(0.05-3.9)
0.25
' (0.01-1.4)
0.5
(0.4-1.0)
370
(200-610)
BOD,.
*5
40
(6.3-57)
8
(6.3-11)
17
(9.4-27)
-
TSS
2500
(449-6594)
400
(71-620)
670
(19-1320)
-
Extracted from Chapter 2, Table 2-13
4-28
-------
Simulation methods—models containing components of each of the above methods
which attempt to simulate the behavior of processes known to influence
the variable of interest.
Regression equations like the Universal Soil Loss Equation and the urban
runoff equations used in Chapter 3 are examples of empirical approaches.
The data bases upon which empirical models are built determine their ability
to satisfy the needs of any given task. Use of such methods in solving
problems outside the range of the original data base is risky and should be
done only with full recognition of the possible errors.
Deterministic models are most elegant in their treatment of any problem.
However, for NFS load assessment studies, the current lack of understanding
of nonurban watershed dynamics and the apparent inability to measure all the
necessary parameters make such models alraost impossible to use. Some
associated specific problems can be solved in this manner. Pipe and rigid-
boundary, open-channel flow are amenable to deterministic modeling.
Stochastic models are becoming popular tools in water resource problem-
solving (14). These methods require large amounts (in space and time) of
data generally not available for water quality assessment studies. But when
prediction of pfe'cipitation and streamflow is needed, and data for long
periods of record are available, such techniques can be effectively applied.
Simulation models are especially attractive for use in nonpoint source
assessment because they permit application of the state-of-the-art for each
process of interest. For example, erosion modeling is still largely an
empirical science, while overland flow can be treated deterministically.
Simulation can combine both approaches to estimate sediment transport.
Another key feature of simulation models is their ability to predict system
responses from system changes - an obvious need when evaluating alternative
future policies.
Application of any of the above models to estimation of NFS loads requires
calibration and testing (some prefer the term verification). For some
empirical models, like regression equations, both are trivial tasks because
the exact form of the model is determined by the available data. The test
for "accuracy" is inherent and is reflected in the statistical measures of
4-29
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correlation. Other empirical models like the urban loading method presented
in Chapter 3 are calibrated by applying the model to the measured data and
calculating the parameters and coefficients which appear as unknowns in the
equations. Empirical models will yield better results when tested against
data from areas having the same properties as those associated with the
calibration data set. Indeed, the major weakness of empirical approaches is
their inability to accoraodate changes in the watershed. Calibration of
deterministic models consists of estimating the physical constants applicable
to the system under study. Testing is inherent because deterministic
formulations are developed from well-understood, thoroughly-tested theory.
Simulation models require calibration through trial and error or least-squares
fitting procedures. The deterministic features of simulation models require
inputs that are independent of time-varying, measured data (e.g., flow, water
That
is, part of the data set is used for calibration to adjust model parameters
and the remaining data are simulated to determine how well the model.predicts
"future" loadings.
Nonurban, nonpoint source models can also be evaluated by comparing their
properties to the watershed-hydrologic system described in section 4.2.2.
This can be done for all models regardless of their classification among
empirical, deterministic, stochastic, or simulation. Three fundamental
properties can be listed: (1) spacial resolution, (2) temporal resolution,
and (3) transport assumptions. Any NFS loading method or model can be
evaluated by separation according to these properties. The resulting
information is useful in determining the appropriate model for application to
any given problem. The following sections describe these properties.
4-3*1 Spatial Resolution
Data are used during the development of most loading models and the resulting
model spatial scale is directly related to the spatial scale of the data
sources. Spatial scales for NFS assessment models are almost the same as
those for the data described in section 4.2.3 with one exception. Models for
conditions at a point, corresponding to the soil column studies, have limited
application to NFS loading estimation and are not included here. Such models
may be useful in studying leaching -problems from residuals disposal areas or
4-30
-------
for investigating the impact of certain practices on the soil-plant-water
complex but these are not normally a part of a general NFS assessment study.
NFS loading models have been developed for field scale or small plot areas,
first-order watersheds, and complex drainage basins. Figure 4-2 illustrates
these three levels of spatial resolution.
Field Scale: The field scale unit is the basic building block for the larger
area models. The "field" varies in size from a few to a few hundred acres.
Runoff loads calculated from such areas are limited to direct surface runoff
and a small portion of the shallow, subsurface flow (interflow). Only single
land uses are represented but these models are ideally suited for evaluating
the relative effectiveness of alternative management practices. For example,
all soil conservation farm planning is based on techniques developed for field
size areas.
Models having only a field scale spatial resolution are subject to the same
caveats as the concomitant data bases. Only a portion of the hydrologic
system is represented and certain attenuating processes (sediment deposition,
adsorption during subsurface flow, etc.) are not included. As a result, the
sum of field loadings for a large basin usually exceed measured water quality
at a point downstream in the same basin.
First-Order Watershed: A first-order watershed is Hydrologically defined as
any watershed which is drained by a stream having no tributaries
above its confluence. For purposes of this manual, a modification to that
definition is proposed - a first-order watershed is any watershed whose water
quality is not influenced by in-stream processes (chemical, biological, etc.).
The size of such watersheds varies for different regions but is generally
limited to less than^two square miles. Several land uses are possible at this
scale, so the models should have the capability for predicting multi-land use
loadings. All components of the hydrologic cycle can be observed in first-
order watersheds so that models should (not all do) predict loadings in both
surface and subsurface flows.
Complex Drainage Basin: Estimating NFS loading at some point "downstream" in
a large watershed having varying land use and a complex hydraulic drainage
network cannot be accomplished unless in-stream water quality changes are
4-31
-------
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31dl/\IVX3 HVOI13H10dAH
CVSTI 'y3Aiy Hinos)
-n
-rfVt'.'.t'-
vXv.sv/.'.v.v.v
* . , + t t t + + t*tTtt+;
%% t t t t t T * t * * *-t*^
,/T T T + + * t t T T i + T t^
feaiJ* 0£ dw t + * T.1r t ^
31VOS NISV8
Nisva
(M
to
I
-------
included as part of the model. For this reason, no generalized "loading only"
model has been developed and tested. Indeed, testing might well prove
impossible. Empirical models and regression equations can be developed with
data collected at any downstream point but the result is an equation that
lumps together land use and water quality impacts. The additional set of
factors included in the model make accurate extrapolation almost impossible.
It is possible, however, to construct models based on first-order watershed
scale calculations which may provide good estimates of loads with the
accompanying assumption that such loads are conservative. Although these
models are difficult to verify, their outputs can be useful in evaluating the
relative benefits of various control alternatives applied to large areas.
4.3.2 Temporal Resolution
The second fundamental property of NFS loading models is the time period over
which they predict loads. Again, comparison of these time intervals with the
behavior of the watershed system response described in section 4.2.2 provides
insight into the most appropriate choice of analysis methodology. Three
approaches representing different time intervals are available as follows: (1)
single event, (2) annual average, and (3) continuous simulation over any
specified time interval. Figure 4-3 illustrates the output of each approach.
Each time interval will now be examined in more detail.
Event Models: Event models are predicated on the assumption that a "design"
load can be estimated and its water quality impact determined. This "worst
case" analysis has been popular in hydraulic structure design but its use in
nonurban, NFS loading estimation is currently quite limited. The major
difficulty with this approach is estimation of the antecedent conditions,
especially those related to pollutant availability for transport by runoff.
Recall from the earlier discussion of land use that land use activities and
their timing combine with various environmental conditions to determine the
concentration, form, and location of pollutants for subsequent transport via
the hydrologic cycle. Since these processes occur between individual events,
their results must be established as boundary conditions for each model run.
Annual Average Models: The major water quality impact of some pollutants is
exerted over long time periods. For example, nutrient loads to a large
impoundment may be adequately described by the total annual load. If sediment
4-33
-------
SINGLE EVENT
U- O
u. x
O V.
Z U)
D Id
K X
O
EVENT '
TIME
TIME
TIME
ANNUAL AVERAGE OF ALL EVENTS
RUNOFF
NCHES/HOUR
n
-fl-n-n-nR R---H---'-
-
/-TOTAL VEARLY
/ (COMPARABLE TOA
/ CONTINUOUS EVENT)
•« • TIMF »J
CONTINUOUS DISTRIBUTION OF RUNOFF EVENT
RUNOFF
INCHES/HOUR
|
\K
Ur\ K
A
L
* TIMF •.
FIGURE 4-3
TEMPORAL RESOLUTION OF RUNOFF PROCESS
4-34
-------
deposition is the problem, the total annual load may suffice for an assessment
decision. For these situations (and for others not so well suited) models
have been developed that predict annual average loadings. In some cases,
total water yield is estimated as the transporting medium, while in others,
sediment yield is used as the transport medium. Most notable among these
models are those based on erosion prediction by the Universal Soil Loss
Equation (15). Annual average loading can be distributed on a daily basis
as was done in the examples of Chapters 2 and 3.
Continuous Simulation Models: The most complete description of the watershed
response is provided by models that attempt to predict all loadings by contin-
uously simulating the hydrologic cycle and its interaction with land use
activities. Such techniques require more data inputs and calculation time.
The need to predict loadings in this manner may depend on the pollutants of
interest and their anticipated impact. For example, pollutants like pesti-
cides that exhibit a short-term water quality impact from peak loading can
hardly be predicted by annual average techniques or event models that require
a_ priori specification of the timing of peaks in pollutant availability on the
watershed. An added advantage of continuous simulation is the ability to
predict event or annual average loadings. It is, of course, possible to
construct a continuous model from single event models by addition of the
between-event processes.
4.3.3 Transport Assumptions
The hydrologic cycle provides the pathways and energy to transport pollutants
to surface or groundwater. Pollutants will be transported with the sediment
carried by overland flow or dissolved in both overland and sub-surface flow.
The physical-chemical processes that determine the relative distribution of
pollutants between particulate and dissolved forms are poorly understood and
even more difficult to describe mathematically to the point where the theory
can be incorporated into NFS loading models. A recognition of the partition-
ing phenomenon must be made, however, in both interpreting measured data and
predicting loads via models. Models have been designed that assume all
pollutants are attached to (or behave as) sediment while others attempt to
partition pollutants between the two transporting media.
4-35
-------
4.3.3.1 Sediment-Based Transport
Sediment-based transport models assume pollutant loads are proportional to
sediment loads. Loads are calculated by predicting sediment loss and applying
the proportionality relationships for each pollutant. Because sediment is
transported by direct surface runoff, sediment-based models are more useful in
predicting pollutants associated with soil surface conditions. Dissolved
constituents ~are not necessarily ignored, however. Sediment transport is also
proportional to runoff volumes and if the relative distribution between water
and sediment does not change, total pollutant losses can be estimated. That
is, if the relationship between pollutants and sediment is determined by
measurements taken for the total runoff (water and sediment) it may be
possible to estimate total loads by only predicting sediment losses.
Two problems arise from the sediment-transport assumption. First, much larger
quantities of water than sediment appear in the drainage from watersheds. If
dissolved constituents are ignored, significant NFS loads will also be
ignored. The fact that subsurface flow accounts for a higher percentage of
the total runoff as the watershed size increases further highlights this
problem. Nitrate loading estimates are not included in sediment-based models.
The second problem arises from the interaction of pollutants and sediment
particles. Sorption is a function of surface area which in turn is determined
by the particle size. Relationships of surface area to textural classes have
been developed by Frere et al. (11). Using a three-level distribution,
the specific surface area can be calculated by:
SS = 200 (%C1) + 40 (%Si) +0.5 (%Sa) (4-1)
2
where SS = specific surface area, m /g
' %C1 = clay content of soil, fraction of total
%Si = silt content of soil, fraction of total
%Sa = sand content of soil, fraction of total
Equation(4-1)shows that the clay content of soil largely determines the
surface area available for interaction with pollutants.
The impact of equation(4-1)on sediment-based loading models results from the
mechanics of the erosion process. Analysis of eroded and in_ situ soil samples
for a given area show that erosion is a selective process resulting in a
4-36
-------
greater percentage of finer material (clays, silts) in the eroded soil than in
the original material. The net result is a different relationship between
pollutants and sediment in runoff than in the soil profile. Most erosion
models predict only gross soil movement. That is, no distinction is made
among soil particles sizes. To accommodate this problem, an "enrichment ratio"
is often applied to predicted loads to increase the concentration of
pollutants in or on eroded soil. Numerical estimates of the enrichment ratio
are included-in section 4.4.5.
Sediment-based transport models can also estimate loadings for pollutants that
behave like inorganic sediment during transport. Organic matter (plant
residues, animal wastes, etc.) and crystalline or precipitated chemicals may
not be sorbed to soil particles but may be part of the total suspended solids
measured in runoff water. If such materials have specific gravities less than
inorganic sediments, their presence will increase the measured enrichment
ratio because of preferential movement by runoff water.
4.3.3.2 Partitioned-Based Transport
Land use activities combined with environmental conditions within a watershed
determine the type, form, and distribution of pollutants. A whole series of
complex processes combine to determine for any given pollutant the relative
distribution between dissolved and particulate forms. In some cases the
distribution is a simple one-way shift from particulate to dissolved as a
result of decay or leaching. Usually, however, equilibrium is reached with
shifts dependent on pollutant concentration and environmental conditions.
If partitioning processes are included in loading models, the dissolved and
particulate loads can be calculated. For example, ammonium (NH.) is
transported in both runoff water and adsorbed on sediment. If partitioning
constants for NH. are known for a given soil, loads in water and sediment can
be estimated. Currently available models assume adsorption reaches
instantaneous equilibrium and represent the process by a variation of the
Freundlich equation. The Freundlich equation is:
C = KC1/n (4-2)
cL
4-37
-------
where C = pollutant adsorbed per unit weight of soil
3.
K, n = empirical constants
C = pollutant concentration in dissolved phase
Note that when n = 1, equation (4-2)reduces to the linear case and a simple
partitioning coefficient, K, characterizes the process.
The addition of partitioning capability to NFS loading models obviously
enhances their ability to yield reliable results. Unfortunately, the data
requirements, model sophistication, and computer run-time requirements also
increase. Considerable thought should be given to design of the study plan if
such models are chosen for assessment studies so that the most efficient model
use can be achieved. Optimum strategies are impossible to specify now because
so little experience is available to draw upon.
4.3.4 Classification of NFS Models
Nonpoint source models should be evaluated in t?he same manner that measured
runoff data are analyzed. Namely, how do model properties and capabilities
compare with the behavior of the watershed system depicted by Figure 4-1. A
complete analysis of each available model along with sample runs, etc., is
beyond the scope of this manual, but it is possible to classify the key models
or techniques according to the fundamental properties (spatial, temporal, and
transport) of importance. Table 4-16 shows the classification of selected NFS
loading models.
Appendix A, Model Applicability Summary, presents a brief summary of major
stormwater and water quality models and includes some discussion related to
two of the models shown in Table 4-16 (AGRUN and ARM). For those models not
included in Appendix A, a similar analysis is provided in the following
sections.
NFS: The Nonpoint Source Pollutant Loading Model (NFS) was developed by
Hydrocomp, Inc., for EPA. The model was specifically designed for use in
planning studies and is compatible with existing water quality impact models.
The model is comprised of subprograms to represent the hydrologic processes in
a watershed, including snow accumulation and melt, and the processes of
pollutant accumulation, generation, and washoff from the land surface. The
hydrologic components, derived from the Stanford Watershed Model, have been
4-38
-------
TABLE 4-16
SELECTED CHARACTERISTICS OF NONURBAN
NONPOINT SOURCE MODELS
Model
Characteristic
Spatial Resolution
Field scale
First-order watershed
Basin
Temporal Resolution
Runoff event
Annual average
Continuous
Transport Assumption
Sediment
Partitioned
NPS
X
X
X
X
X
AGRUN
X
X
X
ACTMO
X
X
X
X
X
ARM
X
X
X
X
X
MRI
X
X
X
X
Reference
20
35
11
10
15
4-39
-------
previously tested and verified on numerous watersheds across the country. The
sediment and pollutant transport components have been tested on several urban
and rural watersheds for selected pollutants and are currently undergoing
additional testing. The simulation of pollutants is based on sediment as an
indicator. Erosion processes are simulated and' the resulting loads are
converted to pollutant loads by user-specified "potency factors" that indicate
the pollutant strength of the sediment for each pollutant simulated.
The NFS model can simulate loads from a maximum of five different land uses in
a single production run. In addition to runoff, water temperature, dissolved
oxygen, and sediment, the NFS model can simulate up to five user-specified
pollutants from each land use category.
Documentation of the model, complete with a user manual and program listing,
is available from EPA in a report entitled "Modeling Nonpoint Pollution From
the Land Surface," EPA-600/3-76-083,(July 1976).
ACTMO; The Agricultural Chemical and Transport Model (ACTMO) was developed by
the Agricultural Research Service, U.S. Department of Agriculture. The model
consists of three components simulating hydrology, erosion and sedimentation,
and interactions of agricultural chemicals (fertilizers and pesticides) with
the soil-water-plant system. The USDAHL-74 model (16) was used
for the hydrologic component and the Universal Soil Loss equation was modified
to generate erosion/sedimentation. ACTMO is one of two models (ARM is the
other) that simulates the partitioning of pollutants between water and
sediment. The hydrologic model has been tested on several watersheds, the
sediment model has been tested in two locations and the chemical transport
model is essentially untested. Current status of model development is
unknown.
Documentation of the model is available from ARS-USDA in a report entitled,
"ACTMO - An Agricultural Chemical Transport Model," ARS-H-3, (June 1975).
MRI; The Midwest Research Institute (MRI) developed for EPA a series of load-
ing functions for assessment of water pollution from nonpoint sources. These
loading functions assume the form of algebraic equations that can be solved
analytically without the aid of computers. Functions for essentially all
nonpoint sources and pollutants are included. For most cases, modifications
4-40
-------
of the USLE are used. Daily loads are calculated from annual average
estimates. In addition, a methodology is proposed for estimating the maximum
and minimum thirty-day loads. This set of functions is consistent with the
loading models for urban areas in Chapter 3 and will be further expanded via
examples in section 4.5.
Documentation of each loading function complete with supporting data and
references is included in the EPA report entitled "Loading Functions for
Assessment of Water Pollution From flonpoint Sources," EPA-600/2-76-151, (May
1976).
4.4 Nonpoint Source Loading Methods Based on the Universal Soil Loss
Equation
Most nonpoint source models estimate pollutant loads by relating pollutants to
sediment. The problem is thus reduced to calculating erosion and sedi-
mentation. The Universal Soil Loss Equation (USLE) is an entrenched analyti-
cal tool used for the purpose of soil conservation planning. Because of its
wide-spread use and successful testing over the years, many NPS loading models
have been built around it. Both desk-top analyses like the MRI loading
functions and computer simulation models like STORM, AGRUN, and ACTMO, make
use of the equation in one way or another. Future development of NPS loading
models will likely continue inclusion of USLE variations. For these reasons,
the basic equation, its limitations, extensions, and associated data bases are
included in the following sections. The descriptions are somewhat abbreviated
to avoid needless repetition of excellent references on the subject
Cl, 2, 17).
4.4.1 The Equation
The equation is:
A = RKLSCP (4-3)
where A = average annual soil loss in tons/acre
R = rainfall and runoff erosivity index
K = soil erodability factor
LS = dimensionless topographic factor representing the
combined effects of slope length and steepness
4-41
-------
C = the cover and management factor
P = factor for supporting practices
Note that equation (4-3} includes factors for precipitation (and to a lesser
extent, runoff), soil type, topography, vegetative cover, and structural
controls. Although the form of equation (4-3) is often argued, most of the
erosion processes are included. The influence of runoff on erosion is only
partially implicit in R because of the way in which the data were correlated.
That is, R is calculated directly from rainfall but field data against which R
was correlated included the lumped effects of rainfall and runoff. A major
weakness still prevails if the size of the area expands beyond a field of a
few acres. The influence of runoff in channels on erosion and deposition is
not included. When the equation is used for calculating annual average loads
at a given location, R, K, and LS are fixed, areal properties and yearly
variations in sediment loads result solely from changes in management or
structural controls.
Perhaps the most attractive feature of the USLE, in addition to its ease of
use, is the data base available to aid the user in estimating the equation
factors. The U.S. Department of Agriculture's Soil Conservation Serivce uses
the equation on a nation-wide basis and considerable effort has been devoted
to determination of factors for a wide array of geographical locations, soil
types, cropping systems, topographical configurations, and tillage operations.
Detailed guidance on selection of the most appropriate numerical values for
each factor is included in several of the references given in the list of
references for this chapter (for example; (1, 2, 17, IS}].Under no
circumstances should equation 4-3 be used in assessment studies before
carefully reading these references.
The USLE Data Base; The data base for the USLE has been reduced to a series
of maps, nomographs, and tables. These data are reproduced in subsequent
sections for easy reference. A more detailed description of each factor is
given, below to aid in parameter selection.
R - The rainfall factor is included in equation @-3)to represent the influence
of precipitation on erosion. R is numerically defined as the number of El
units (erosivity index) for'the specified time period. El is calculated as
the product of two rainstorm parameters: kinetic energy of the storm in
4-42
-------
hundreds of foot-tons per acre times its maximum 30-minute intensity in inches
per hour. Data from weather stations having 22 years or longer of recording-
raingage records were analyzed to determine the long-term, annual average R
values for various locations (18). Results are shown in Figure 4-4. Note
that for use in locations within the shaded portions of Figure 4-4
adjustments to accomodate the influence of snowmelt runoff are required.
Procedures for correction, along with specific recommendations for certain
areas, are available from the Soil Conservation Service Regional Technical
Center, Portland, Oregon. The data were further analyzed to determine the
yearly distribution of R for each region. Curves for each geographical region
have been generated (1, 2). The R value can be estimated by
interpolation between isolines of Figure 4-4 or by analysis of local rainfall
data. For local data, the kinetic energy can be estimated by the following
equation (18):
E = 916 + 331 log X (4-4)
where E = kinetic energy, foot-tons/acre
X = rainfall intensity, inches/hour
The product El is then determined by multiplication of E by the maximum 30-
minute rainfall intensity observed for each storm from which X was abstracted.
K - The soil erodability factor reflects soil properties and is a measure of
the susceptibility to erosion. Numerical estimates for certain soils were
determined by measurements of soil loss per unit of R for a standard set of
conditions established on small plots. A generalized procedure for factor
estimation was then developed as a function of standard, measurable soil
properties. Results are included in Table 4-17 and the nomograph of Figure 4-
5. State and local offices of the Soil Conservation Service also have K
values tabulated for specific soils and should be consulted for advice.
LS - The steepness and length of slope for a given area impact on erosion
rates. The LS factor represents the combined effect of these two variables
and numerical estimates have been determined by analysis of experimental data
(1). Results are shown by the solid lines in Figure 4-6. Two important
features of these data should be noted. First, the data. were, taken from
studies involving slopes with a specific range of steepness and length (refer
4-43
-------
REFERENCE: (2)
FIGURE 4-4
AVERAGE ANNUAL VALUES OF THE RAINFALL-EROSIVITY FACTOR, R
-------
TABLE 4-17
INDICATIONS OF THE GENERAL MAGNITUDE OF THE ,
SOIL-ERODIBILITY FACTOR, K&
Soil Erodibility Factor, Kb
Organic Matter Content
Texture Class 0.05% 2% 4%
Sand
Fine sand
Very fine sand
Loamy sand
Loamy fine sand
Loamy very fine sand
Sandy loam
Fine sandy loam
Very fine sandy loam
Loam
Silt loam
Silt
Sandy clay loam
Clay loam
Silty clay loam
Sandy clay
Silty clay
Clay
0.05
0.16
0.42
0.12
0.24
0.44
0.27
0.35
0.47
0.38
0.48
0.60
0.27
0.28
0.37
0.14
0.25
0.03
0.14
0.36
0.10
0.20
0.38
0.24
0.30
0.41
0.34
0.42
0.52
0.25
0.25
0.32
0.13
0.23
0.13-0.29
0.02
0.10
0.28
0.08
0.16
0.30
0.19
0.24
0.33
0.29 '
0.33
0.42
0.21
0.21
0.26
0.12
0.19
_
Source: (2)
The values shown are estimated averages of broad
ranges of specific-soil values. When a texture is
near the borderline of two texture classes, use the
average of the two K values. For specific soils, use
of Figure 4-5 or Soil Conservation Service K-value
tables will provide much greater accuracy.
4-45
-------
I
•p>
ON
I- vtry tint granular
2-tint granular
3-m«d or coarst granular
4-blacky, ploty, or motsivt
* SOIL STRUCTURE
PERMEABILITY
PERCENT SAND
(0.10-2.Omm)
5- slow
4- slow to mod.
3- modtrott
2-mod. la rapid
I- rapid
PROCEDURE; With ipproprlite dat«. enter se«1e It left and proceed to potntl representing
the soli's I s*nd (0.10-2.0 im), I organic mitter, structure, ind permeability. In that sequence
Interpolate betMeen plotted curves. The dotted Kne Illustrates procedure for a soli having:
Ki, sand 51, OK 2.61, structure ?. per«at><1tty 4. Solution:* K • 0.31.
REFERENCE: (2)
FIGURE 4-5
SOIL-ERODIBILITY FACTOR (K) NOMOGRAPH FOR U.S. MAINLAND SOILS
-------
20.0
3.5 6.0 10
Slope Length, Meters
20 40 60 100
200
400 600
10 20 40 60 100 200 400 600 1000 2000
Slope Length, Feet
REFERENCE: (15)
NOTE:
THE DASHED LINES REPRESENT ESTIMATES FOR SLOPE DIMENSIONS BEYOND
THE RANGE OF LENGTHS AND STEEPNESSES FOR WHICH DATA ARE AVAILABLE.
FIGURE 4-6
SAMPLE PLOT OF TOPOGRAPHIC FACTOR (LS)
VERSUS SLOPE AND SLOPE LENGTH
4-47
-------
to note on Figure 4-6). Second, the factors apply to uniform sopes only.
Although procedures to correct for the effects of nonuniform slopes have
been developed (15), the impact of slope concavity or convexity is not re-
flected here. The dashed lines of Figure 4-6 represent the extrapolation of
the relationship beyond the data base. Validity of this extension is
currently unknown.
C - Crop cover and management factors act to mitigate erosion rates. While
an annual average C value is often used in the USLE, estimated values, re-
flecting crop growth stages can also be used. Values range from 0.001 for
undisturbed forests to 1.0 for tilled continuous fallow (open, continuously
plowed areas). Tables 4-18 through 4-20 summarize appropriate C values for
agricultural and silvicultural systems. In cases where the USLE is applied
to other land use activities, the C value is approximated by a comparison of
the cover conditions to similar cover conditions for agricultural situations.
For example, construction activities result in bare, exposed, and disturbed
soil surfaces and a C value of 1.0 should be used.
P - Certain other structural or management options related to the landscape
serve to mitigate erosion. Such practices are collectively known as support-
ing practices and include contouring, terracing, strip cropping, etc. The
impact of these practices on erosion are estimated through P, with values
ranging from 0.25 to 1.0. Table 4-21 summarizes the various P values
appropriate for each supporting practice.
4.4.2 A Few Words of Caution
Statistical analyses of the USLE's predictive capability have been performed
and a recent paper by the equation's developer summarized these results along
with important words of caution for users (17). These precautions are
especially noteworthy for those who expand the USLE to aid in estimation of
NPS pollutant loads.
The accuracy of the equation was determined by comparing its average annual
prediction with measured data from 189 field plots scattered across the
country. The overall measured mean soil loss was 11.3 tons per acre. The
average prediction error was 1.4 tons with 84%.of the predictions within 2
4-48
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TABLE 4-18
GENERALIZED VALUES OF THE COVER AND MANAGEMENT FACTOR, C, IN THE 37 STATES
„ K
EAST OF THE ROCKY MOUNTAINS '
Line
number
Productivity
Level
High Moderate
Crop, Rotation, and Management
Base value: continuous fallow, tilled up and down slope
Corn
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Cotton
27
28
Meadow
29
30
31
C, RdR, fall TP, conv (1)
C, RdR, spring TP, conv (1)
C, RdL, fall TP, conv (1)
C, RdR, we seeding, spring TP, conv (1)
C, RdL, , standing, spring TP, conv (1)
C, fall shred stalks, spring TP, conv (1)
C (silage) -W(RdL, fall TP) (2)
C, RdL, fall chisel, spring disk, 40-30% re (1)
C (silage, W we seeding, no-till pi in c-k W (1)
C (RdL) -W (RdL, spring TP) (2)
C, fall shred stalks, chisel pi, 40-30% re (1)
C-OC-W-M, RdL, TP for C, disk for W (5)
C, RdL, strip till row zones, 55-40% re (1)
C-C-C-W-M-M, RdL, TP for C, disk for W (6)
C-C-W-M, RdL, TP for C, disk for W (4)
C, fall shred, no-till pi, 70-50% re (1)
C-C-W-M-M, RdL, TP for C, disk for W (5)
C-C-C-W-M, RdL, no-till pi 2d § 3rd C (5)
C-C-W-M, RdL, no-till pi 2d C (4)
C, no-till pi in c-k wheat, 90-70% re (1)
C-C-W-M-M, no-till pi 2d & 3rd C (6)
C-W-M, RdL, TP for C, disk for W (3)
C-C-W-M-M, RdL, no-till pi 2d C (5)
C-W-M-M, RdL, TP for C, disk for W (4)
C-W-M-M-M, RdL, TP for C, disk for W (5)
C, no-till pi in .c-k sod, 95-80% re (1)
e
Cot, conv (Western Plains) (1)
Cot, conv (South) (1)
Grass $ Legume mix
Algalga, lespedeza or Sericia
Sweet clove-r
C Value
1.00
0.54
0.50
0.42
0.40
0.38
0.35
0.31
0.24
0.20
0.20
0.19
0.17
0.16
0.14
0.12
0.11
0.087
0.076
0.068
0.062
0.061
0.055
0.051
0.039
0.032
0.017
0.42
0.34
0.004
0.020
0.025
1.00
0.62
0.59
0.52
0.49
0.48
0.44
0.35
0.30
0.24
0.28
0.26
0.23
0.24
0.20
0.17
0.18
0.14
0.13
0.11
0'.14
0.11
0.095
0.094
0.074
0.061
0.053
0.49
0.40
0.01
4-49
-------
Line
number
TABLE 4-18
(Continued)
Crop, Rotation, and Management
Productivity Level
High Moderate
C Value
1.00
Base value; continuous fallow, tilled up and down slope
e
Sorghum, Grain (Western Plains)
32 RdL, spring TP, conv (1) 0.43
33 No-till pi in shredded 70-50% re 0.11
e
Soybeans
34 B, RdL, spring TP, conv '(1) 0.48
35 C-B, TP annually, conv (2) 0.43
36 B, no-till pi 0.22
37 C-B, no-till pi, fall shred C stalks (2) 0.18
1.00
0.53
0.18
0.54
0.51
0.28
0.22
W-F, fall TP after W (2)
W-F, stubble mulch, 500 Ibs re (2)
W-F, stubble mulch, 1000 Ibs re (2)
Spring W, RdL, Sept TP, conv (N § S Dak) (1)
Winter W, RdL, Aug TP, conv (Kans) (1)
Spring W, stubble mulch, 750 Ibs re (1)
Spring W, stubble mulch, 1250 Ibs re (1)
Winter W, stubble mulch, 750 Ibs re (1)
Winter W, stubble mulch, 1250 Ibs re (1)
W-M, conv (2)
W-M-M, conv (3)
W-M-M-M, conv (4)
0.38
0.32
0.21
0.23
0.19
0.15
0.12
0.11
0.10
0.054
0.026
0.021
Source: (2)
This table is for illustrative purposes only and is not a complete list of
cropping systems or potential practices. Values of C differ with rainfall
pattern and planting dates. These generalized values show approximately the
relative erosion-reducing effectiveness of various crop systems, but
locationally derived C values should be used for conservation planning at
the field level. Tables of local values are available from the Soil
Conservation Service.
High level is exemplified by long-term yield averages greater than 75 bu.
corn or 3 tons grass-and-legume hay; or cotton management that regularly
provides good stands and growth.
wimbers in parentheses indicate number of years in the rotation cycle.
Number (1) designates a continuous one-crop system.
4-50
-------
TABLE 4-18
(Continued)
e
Grain sorghum soybeans, or cotton may be substituted for corn in lines 12,
14, 15, 17-19, 21-25, to estimate C values for sod-based rotations.
Abbreviations defined: B = soybeans
C = corn
c-k e chemically killed
conv = conventional
cot = cotton
F = fallow
M = grass § legume hay
pi = plant
W, = wheat
we = winter cover
Ibs re = pounds of crop residue per acre
remaining on surface after new crop
seeding
% re = percentage of soil surface covered by
residue mulch after new crop seeding
70-50% rc= 70% cover for C values in first column;
50% for second column
RdR = residues (corn stover, straw, etc)
removed or burned
RdL = all residues left on field (on surface
or incorporated)
TP = turn plowed (upper 5 or more inches of
soil inverted, covering residues)
4-51
-------
TABLE 4-19
C FACTORS FOR PASTURE, RANGELAND, AND IDLE LAND
a,b
Vegetative Canopy
Type and Height of
Raised Canopy
No appreciable canopy
Canopy of tall weeds
or short brush CO-5 m
fall height)
Appreciable brush or
bushes (2 m fall
height)
Trees but no appreci-
able low brush (4 m
fall height)
Canopy
Cover,
% Type6
25
50
75
25
50
75
25
50
75
Cover that Contacts the Surface
Percent Ground Cover
20
40
60
80
95-100
G
W
G
W
G
W
G
W
G
W
G
W
G
W
G
W
G
W
G
W
0.45
0.45
0.36
0.36
0.26
0.26
0.17
0.17
0.40
0.40
0.34
0.34
0.28
0.28
0.42
0.42
0.39
0.39
0.36
0.36
0.20
0.24
0.17
0.20
0.13
0.16
0.10
0.12
0.18
0.22
0.16
0.19
0.14
0.17
0.19
0.23 '
0.18
0.21
0.17
0.20
0.10
0.15
0.09
0.13
0.07
0.11
0.06
0.09
0.09
0.14
0.085
0.13
0.08
0.12
0.10
0.14
0.09
0.14
0.09
0.13
0.042
0.090
0.038
0.082
0.035
0.075
0.031
0.067
0.040
0.085
0.038
0.081
0.036
0.077
0.041
0.087
0.040
0.085
0.039
0.083
0.013
0.043
0.012
0.041
0.012
0.039
0.011
0.038
0.013
0.042
0.012
0.041
0.012
0.040
0.013
0.042
0.013
0.042
0.012
0.041
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
aSource: (15)
All values shown assume: 1) random distribution of mulch or vegetation, and
2) mulch of appreciable, depth where it exists.
cAverage fall height of waterdrops from canopy to soil surface, m = meters.
Portion of total-area surface that would be hidden from view by canopy in a
vertical projection (a bird's-eye view).
A
G = Cover at surface is grass, grass-like plants, decaying compacted duff,
or litter at least 5 cm (2 in.) deep.
W = Cover at surface is mostly broadleaf herbaceous plants (as weeds) with
little lateral-root network near the surface and/or undecayed residue.
4-52
-------
TABLE 4-20
C FACTORS FOR WOODLANDa
Stand Condition
Well stocked
Medium stocked
Poorly stocked
Forest
b c
Tree Canopy Litter
Percent, of Percent of
Area Area
Undergrowth
C Factor
100-75
70-40
35-20
100-90 Managed6 -
Unmanaged6
85-75 Managed
Unmanaged
70-40 Managed
Unmanaged
0.001
0.003-0.011
0.002-0.004
0.01-0.04
0.003-0.009
0.02-0.09
Source: (15)
When tree canopy is less than 20%, the area will be considered as grass-
land or cropland for estimating soil loss.
°Forest litter is assumed to be at least 2 inches deep over the percent
ground surface area covered.
Undergrowth is\defined as shrubs, weeds, grasses, vines, etc., on the
surface area not protected by forest litter, Usually found under
canopy openings.
Managed = grazing and fires are controlled.
Unmanaged = stands that are overgrazed or subjected to repeated burning.
For unmanaged woodland with litter cover of less than 75%, C values
should be derived by taking 0.7 of the appropriate values in Table 4-19
The factor of 0.7 adjusts for the much higher soil organic matter on
permanent woodland.
4-53
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TABLE 4-21
P VALUES FOR EROSION CONTROL PRACTICES ON CROPLANDS'
Erosion Control Practice
Range of
Slope
2.0-7
7.1-12
12.1-18
18.1-24
Up and
Down Hill
1.0
1.0 '
1.0
1.0
Cross-Slope
Farming
Without Strips
0.75
0.80
0.90
0.95
Contour
Farming
0.50
0.60
0.80
0.90
Cross-Slope
Farming
With Strips
0.37
0.45
0.60
0.67
Contour
Strip -
Cropping
0.25
0.30
0.40
0.45
Source: (1)
4-54
-------
tons of the"measured losses. Further analysis also showed that larger errors
were associated with measured data collected over shorter time periods than
the 22-year cycle chosen for the R data base.
Considerable error can result if the equation factors are estimated
incorrectly for large areas where watershed sediment yield is the objective.
The author states..."Applying the equation to a complex watershed by using
overall averages of slope length and gradient with estimated watershed-average
value for factors K and C would be incorrect. To use the equation correctly,
the combination of selected factor values must reflect the manner in which the
parameters are associated in each subarea....Perhaps the greatest potential
source of prediction error is superficiality in selecting factor values....If
the selected values do not truly represent the conditions to be evaluated,
neither will the computed soil loss." (17).
4.4.3 Sediment Delivered to the Stream
Gross erosion as predicted by the USLE suffers the same limitation as pollu-
tant loss data collected at the outlet of plots or small fields - the load to
the stream is significantly less than these values because other components of
the hydrologic system act to attenuate their magnitude. For sediment,this
attenuation is a function of many variables including soil characteristics,
watershed area, slopes, slope length, relief/length ratio, and drainage
density. Erosion from gullies or the stream channel itself is a contributor
to downstream sediment load but is not included in the USLE predictions.
Correction for the efficiency of a watershed system to yield eroded sediments
to a point downstream is made by application of a sediment delivery ratio
(SDR). The SDR is defined as the ratio of sediment delivered at a location in
the stream system to the gross erosion from the drainage area above that
point.
Ideally, one could structure a model using sediment transport theory and route
both water and sediment through the system. Failing that, most investigators
have chosen to develop empirical relationships (based on data) for sediment
delivery including one or more of the variables listed above. The results of
a recent development for use with NFS loading functions are given in Figure
4-7. Drainage density in Figure 4-7 is defined as the ratio of total channel-
4-55
-------
I
tn
I/Drainage Density, Kilometers /Kilometer
1.0 10 . 100 *XpO 500
Silty Clay
Predominantly Silt
REFERENCE: (15)
I I I I I I II I I I I t I M1 I I I i I I i i I I t
I I I I I I
0.02
1.0 10
1/lDrainage Density, Miles2/Mile
FIGURE 4-7
SEDIMENT DELIVERY RATIO FOR RELATIVELY HOMOGENEOUS BASINS
400
-------
segment lengths to the basin area. Note also the different relationship for
each soil particle size class. This distinction is made to accommodate the
greater ease with which finer materials are transported.
Application of the SDR to the USLE enables the analyst to estimate loads to a
specific point in the stream. A sediment yield equation is thus given by:
Y(S) = A(RKLSCP)Sd (4-5)
where Y(S) = sediment loading to stream, tons/yr
A = area, ac
RKLSCP = factors of USLE
S, = sediment delivery ratio
If data are available for the area of interest, S, should be validated, if
possible, by analysis of the data. Usually, reservoir sedimentation rates
are the most commonly available data sources.
4.4.4 A Few More Words of Caution
The USLE does not estimate erosion from gullies, stream banks, or head cuts.
Delivery ratios based on locally measured data may include the lumped effects
of these sources as well as the sources estimated by the USLE. The most
appropriate value is given by:
SY
Sd = SH + GU + CH C4"6)
where SY = sediment yield at point of interest
SH = USLE related erosion
GU = gully erosion
CH = channel erosion
Note that if S, is determined from measured data that accounts for only SH in
the denominator of equation 4-6, the resulting ratio will be too high when
applied to new values of SH for prediction of SY. To illustrate this possible
source of error, data from a recent paper on sediment yield from two water-
sheds in the Mississippi Delta were analyzed (19) > The study
reported estimates of each source of erosion (sheet, gully, and channel) and
the total watershed sediment yield. Calculated 15-year mean sediment delivery
ratios were 0.28 and 0.57, respectively. Calculation of similar values, but
4-57
-------
based on estimates for sheet erosion only (per USLE), yielded ratios of 0.42
and 0.80, respectively. Use of these uncorrected delivery ratios in NFS
assessment studies would result in the estimated values being 150% and 14n% of
the actual loads.
4.4.5 MRI Loading Functions
The final step in developing a series of pollutant loading functions based on
.sediment delivered to the stream is correlation of pollutants to sediments.
Two options are available. A direct ratio of pollutants to sediment can be
determined by field sampling followed by calibration of equation (4-5). A
similar procedure is recommended for models like the NFS (20) and
STORM (21). The other option is a correlation between pollutants
and in_ situ soil along with a factor to correct for the enrichment process
discussed in section 4.3.3. Midwest Research Institute (15) used
this approach and developed a series of loading functions having the form:
Y(P)E = aY(S)E Cs(P)rp (4-7)
where Y(P)R = pollutant, P, load to streams
Ci
a = dimensional constant
Y(S)E = sediment loading to stream (using equation (4-5))
C (P) = concentration of pollutant, P, in soil profile
s f
r = enrichment ratio for pollutant, P
The enrichment ratio, r , corrects for the observed phenomena that pollutants
in eroded sediments are somewhat more concentrated than the same pollutants in
the watershed soil profile.. Numerical values are simply the ratio of the two
concentrations. The need for such a ratio is not surprising in view of the
surface area differences among soil fractions. That is, the much greater
surface area associated with the finer, more erodable particles (see equation
(4-1))..
Equation(4-7)is further modified for certain pollutants to account for the
"unavailability'-' of portions of the load. For example, if equation(4-7)were
used to estimate only total phosphorus loadings, determining,the water quality
impact would be difficult because it is only the biologically available phos-
phorus that exerts the impact. This correction is made by simply multiplying
4-58
-------
equation (4-7)by an availability factor (percent of load that is immediately
available for use by plants or animals).
A summary of the MRI loading functions is given in Tables 4-22 and 4-23.
Details of their development and additional information is included in the EPA
report entitled "Loading Functions for Assessment of Water Pollution From
Nonpoint Sources," EPA-600/2-76-151,(May 1976).
The most accurate results from equation (4-7)can be expected when the long-term
average annual loads are estimated. The temporal distribution of the annual
loads is important in water quality impacts, however, especially for those
pollutants exerting short-term impacts. To accommodate the necessity to esti- .
mate peak loads over a one-year period,two methods are proposed.
First, if one assumes that the only variation in the USLE factors for a given
area is that attributed to rainfall, then, it is possible to distribute the
loads according to the distribution of R. That is, all factors in the USLE
are considered fixed except for R. The variation in R is determined by
cumulative distribution curves developed by the Soil Conservation Service
(1) and reproduced by MRI (15). Figure 4-8 generated (15) from the cumulative
distribution curves, is expressed in units of percent of gross
surface erosion expressed on a daily basis. The percent of the annual erosion
for each time period is easily determined by multiplying each data point (for
each month) by the number of days in the month. The shape of the curve will
obviously remain the same.
The assumption that all factors of the USLE will remain the same throughout
the year is unlikely for land uses subject to operations like agriculture.
For these situations, the curve is further modified by the C factor. Periods
for which the C factors are different are determined and the product RC is
used to distribute the loads. Results for continuous corn in central Indiana
is given in Figure 4-9. Note the synergistic effects of both the high R
values and high C values for the mid-June to mid-July period resulting in
maximum loadings for the year.
The MRI Loading Functions Data Base: The MRI document repeatedly stresses the
value of obtaining locally derived data inputs from knowledgeable sources.
This advice is indeed appropriate, and typical sources are listed in Appendix C
as well as the MRI report (15). In cases where local data are
4-59
-------
ON
O
TABLE 4-22
LOADING FUNCTIONS SUMMARY21
Loading Type
or Source ' Loading Function Description
Sediment n
(Agriculture) Y(S)£ . ^ (A-R-K-L-S-C-P-S^
Nitrogen Y(NT) • a-Y(S) -C (NT) T
v c c S ni
Y(NA) = Y(NT) • f + Y(N)
c en rt
0 f OR1)
Y(NA) = Y(NT)E • fN * Y(N)pr
Phosphorus Y(PT) = a • 1f(S)E • CS(PT) • rpT
Y(PA) = Y(PT) • fp
Organic Matter Y(OM)E « a • Y(S)£ • Cs(OM) • rom
Pesticides VCHTB^ = n' . r CHTBI . vrsi . ,.
(Herbicides, Y(HIF) a CS(HIF) YCS>E rHIF
Insecticides, vrmri = • r n r „
Fungicides) Yt"IF' i5lQi i
Salinity Y(TDS)TD., = a • A • C(TDS)-U • (IRR + Pr-CU)
IKr on
Y(TDS)IRF = a-CQ(str)B-C(TDS)B-Q(str)A.C(TDS)A)
- Y(TDS)B(, - Y(TDS)pT
Y(TDS)TD_ = (TDS)ID_ • A
IKr IKr
Sediment n
1) Silviculture Y(S) « .J-CA-R-K-L'S-C-P.M-S.)
2) Construction
3) Surface Mining
Acid Mine Y(AMD) = NIKa-CI^+Ijy+I^+Ijgj-Kb-QCR) ^(AUK)^]
Drainage y(AMD) _ B.A.QCR).(CCS04)-CCS04)B(,-C(S04)pT)
Y(AMD) - a-Q(str)-(C(S04)-C(S04)BG-C(S04)pT)
Heavy Metals/ vrHMl = .r niMl • vfsi
Radioactivity Js " a ^ sl " JE
Y(HM) = a i|1Qn • C(HM)n
Y(IW) « a • A • Q(R) (C(HM) - C(HM)B(.)
Y(IIM) - a • Q(str) (C(I1M) - C(IIM)BG)
Feedlots Y(i)pL • a • Q(FL) • C(i)pL • FLd • A
Terrestrial v/•^ t*r*\ nnv\ TT? A
Disposal YWLF " a ' C(l)LF ' Q(LF) ' LFd ' A
Applicable to agricultural land; may he modified with multipliers to represent
silviculture, construction, surface mining
The first loading function represents total nitrogen yield from sediment. The
second loading function represents total available nitrogen in sediment. The
third function represents the precipitation borne nitrogen loading that is
transported via overland flow. The last function is total available nitrogen.
The first loading function represents total phosphorus yield. The second loading
function represents total availabel phosphorus. There is no phosphorus in
precipitation.
Can be used to estimate BOD loadings.
Based on average pesticide residual (nonpeak loads). Used for insoluble
pesticide, if average soil concentration known.
Used for water soluble and insoluble pesticide loadings
Source-to-stream methodology
Stream-to-source methodology
Requires areal salt loading rates based upon accumulated results of strean
monitoring program.
M is a multiplier indicating the effect of different types of disturbances.
Nutrient loads are assumed to be only inorganic.
The appropriate equation to be used for calculating acid nine drainage depends
upon the region of the county. The first two loading functions reflect a source-
to-stream approach; the next two reflect a stream-to-source estimating procedure.
Estimating procedure for heavy metals and radioactivity loads are identical '
except that heavy metals go in as "ppb" and radioactivity as "picocuries/liter"
Overland runoff approach; not related to sediment
Subsurface/groundwater return flow, in the form of Icachatc
fa\ /* •! P* ^
1 •'These loading functions are derived and explained by MRI in Reference l.-1-Jj
-------
TABLE 4-23
LIST OF SYMBOLS USED IN TABLE 4-22
i
o\
A
AMD
AS; AU
BG
C
C (i)
DD
E
HM
I
IRF
IRR
IS; IU
K
L
LF; LF,
LS d
HA
OM
OR
P
P
Pr
PA
PD
PT
Q;J Q
QtFL)
Q(LF)
Source area, ha
Acid mine drainage
Active surface or underground mine
Background source
Cover management factor
Concentration of pollutant i in sediment
Concentration, C of pollutant i in source
Concentration of background alkalinity, mg/liter
Overland distance between erosion site and receptor water, ft
Drainage density, km"
Annual average erosion rate, Ml'/ha/year
Ratio of NA:NT in eroded sediment
Ratio of PA:PT in eroded sediment
Small feedlot source
Feedlot delivery ratio
Herbicide, hisecticide, Fungicide; and pesticide
Heavy metals or radioactivity
Load index for acid mine drainage
Irrigation return flow
Irrigated water added annually to crop root zone, cm/year
Inactive surface or underground mine
Soil erodibility factor
Slope length factor
Landfill, landfill delivery ratio
Topographic factor
Available (or mineralised) nitrogen
Nitrogen yield rate per unit area from precipitation, kg/ha/year
Sum of nitrogen of all chemical forms
Organic matter
Overland runoff
Percolation rate, cm/year
Conservation practice factor
Annual average precipitation, cm/year, storm precipitation, cm
Available phosphorus
Population density, number/ha
Total phosphorus; also point source
Runoff due to a storm event, cm
Feedlot runoff, cm/year
Landfill leachate flow rate, cm/year
Q(OR)
Q(P)
Q(Perc)
QOO
Q(Str)
Q(t)
R
'NT
'OM
TDS
U
Y(AMD)
Y(HIF)
Y(HM)
"'"?LF
. »)U
Y(NA?r
Y(NT)
Y(OM)p
Y(PA)11
Y(PT)
Y(RAD)
Y(S)E
Y(S)U
Y(TDH)
Y(TDS)
Overland runoff, cm/year
Total precipitation flow rate, cm/year
Percolation flow rate, cm/year
Direct runoff, cm/year
Streaii flow rate, liters/sec
Runoff over a period of time, t
Rainfall erosivity factor
Rainfall erosivity fu;tor due to rainfall
Rainfall erosivity factor due to snowaelt
Enrichment ratio for nitrogen (ratio of concentration of
nitrogen in sediment to that in soil)
Enrichment ratio for organic matter (ratio of concentration
of organic matter in sediment to that in soil)
Enrichment ratio for phosphorus (ratio of concentration
of phosphorus in sediment to that in soil)
Slope gradient factor; also sediment
Sediment delivery ratio (ratio of the anount of sediment
delivered to a stream to the amount of on-site erosion)
Total dissolved solids
Composite topographic factor for irregular slopes
Acid mine drainage loading, kg/year
Total pesticide loading, kg/year
Heavy metal loading, kg/year
Loading of pollutant i from small feedlots, kg/year
Loading of pollutant i from landfills, kg/year
Loading of pollutant i from urban areas, kg/year
Nitrogen loading from precipitation runoff, kg/year
Available nitrogen loading, kg/year
Total nitrogen loading from erosion, kg/year
Organic matter loading, kg/year
Available phosphorus loading, kg/year
Total phosphorus loading, kg/year
Loading of radioactive substances, microcuries/year
Sediment loading from surface erosion, MT/year
Loading of street solids from urban areas, kg/year
Salinity (TDS) load from background, kg/year
Salinity (TDS) load in irrigation return flow, kg/year
Salinity (TDS) load from point sources, kg/year
Yield of pollutant i from background, kg/year
-------
<
o
01
UJ
a.
z
o
tn
o
a:
ID
UJ
o
<
U.
cc
Z)
OT
OT
O
CD
U.
O
z
UJ
o
QL
UJ
a.
O.8
0.7 -
0.6 -
O.5 -
JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. JAN.
TIME OF YEAR
REFERENCE: (15)
FIGURE 4-8
PROJECTED VARIATION OF SOIL EROSION
4-62
-------
<
a
QL
UJ
a.
z
o
CO
g
UJ
UJ
o
<
tl_
a:
3
CO
CO
CO
o
u.
o
UJ
o
a:
UJ
a.
F- TURN PLOWING
Cl- SEEDING
C2- ESTABLISHMENT
C3- GROWING CROP
C4-HARV EST AND STUBBLE
JAN, FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC. JAN.
TIME OF YEAR
REFERENCE: (15)
FIGURE 4-9
PROJECTED VARIATION OF SOIL EROSION
4-63
-------
unavailable or where only a first-cut analysis is desired, procedures are
proposed for parameter estimation. Factors associated with sediment loading
were discussed in sections 4.4.1, 4.4.2, and 4.4.3. The following data apply
to the pollutant associated parameters of selected loading functions.
Soil-Pollutant Concentrations - Cs(P) of equation (4-7) - Soil sampling data is
the most reliable and current data available for estimation of Cs(P). Failing
that, however, one can use the maps given in Figures 4-10 and 4-11 for soil
nitrogen and phosphorus content. Organic matter estimates are made by
multiplying the nitrogen values by 20. An alternative method for estimating
nitrogen concentrations is also included in the MRI document (15) but will
not be repeated here.
Enrichment Ratios - (r in equation(4-7))- Estimation of enrichment ratios
without the benefit of locally derived data requires extrapolation at its best
(or worst). Only a few experimental studies have reported measured values and
no theoretical approaches to prediction have been attempted. Table 4-24 gives
typical values for nitrogen and phosphorus. MRI used values of 2.0 and 1.5
for nitrogen and phosphorus, respectively, in solution of example problems.
No experimentally determined values for organic matter are reported, but MRI
suggested a range of from 1.0 to 5.0 and used a value of 2.5 for the completed
example.
Availability Factors - The fraction of total pollutants that are available for
immediate use by aquatic plants, etc., is also difficult to estimate with
certainty. For nitrogen, MRI suggested an upper limit of 15%, reported a
l
value of 8% and used 6% in their completed example. For phosphorus, values of
5% and 10% were reported and 10% was chosen for use in their completed
example. No availability factors were given for organic matter, but the
fraction of organic matter exerting BOD is important from a water quality
impact perspective. Locally determined BOD values for surface soil organic
matter should provide useful information.
4.5 Methodology for Preliminary Assessment of Nonurban Nonpoint Source
Loadings
The techniques and data bases discussed in the previous sections can be used
to assess the nature, magnitude, and extent of nonpoint source pollutant
4-64
-------
•fc.
I
tn
Highly Diverse
Insufficient Data
REFERENCE: (15)
FIGURE 4-IO
PERCENT NITROGEN (N) IN SURFACE FOOT OF SOIL
-------
0.20-0.30
TOTAL P = 0.22XPgOs
REFERENCE: (15)
FIGURE 4-I I
PERCENT PHOSPHORUS { P) IN SURFACE FOOT OF SOIL
-------
TABLE 4-24
SUMMARY OF EXPERIMENTALLY DETERMINED ENRICHMENT RATIOSa
Ratio
Land use
Fallow
Rye winter cover crop
Manure spreading
Agricultural
Nitrogen
3.88
4.08
4.28
3.35
2.0
2.7
Phosphorus
1.59
1.56
1.47
1.47
-
aSource:
No specific activity reported.
4-67
-------
loading. Assessment can be preliminary or comprehensive, depending on the
choice of the methdology and the resources available for analysis. Whatever
the approach taken, interpretation of the data base (both measured and
abstracted from previous studies), and loading predictions should only be made
with due consideration for the hydrologic-watershed system described in
section 4.2.2.
The approach chosen for presentation in the following sections can result in
at best a preliminary assessment and was designed to be consistent with the
analysis for urban loadings presented in Chapter 3. The general approach,
however, is useful as a guide for assessment regardless of the particular set
of tools (models) chosen for use. The methodology is limited to a problem
assessment only - evaluation of alternative control strategies, selection of
controls, and economic analyses are not included.
4.5.1 Statement of the Problem and the Solution Methodology
The Problem: As part of a water quality impact assessment study in a planning
area, a specific (typical) watershed is chosen to evaluate the nature, extent,
and magnitude of NPS loads. Subsequently, an analysis of the water quality
impacts for the water quality limited stream segment into which the watershed
drains will be made. The pollutant types, magnitude, and timing are desired.
The Methodology: The assessment procedure has been divided into six steps, as
shown in Figure 4-12. Each step consists of an activity requiring input
information of the type described. Completion of the activity results in a
series of outputs that are, in turn, available for inputs to the next step or
for decision-making. For steps II, III, IV, and VI, references to previous
sections are given to indicate the location of necessary or useful infor-
mation. To illustrate the methodology each step in Figure 4-12 will be
completed for a hypothetical example consistent with the problem stated above.
Data for step I will be abstracted from a report by the Ohio River Basin
Sanitation Commission (Reference: 22). Steps II through .VI will be completed
using information contained in previous sections of this chapter and certain
other assumptions (hopefully reasonable) that are necessary to complete the
example.
4-68
-------
STEP I
STEP H
STEP IH
STEP IE
STEP:S:
STEP3ZT
INPUTS AND LAND USE SURVEY SECTION 4.2.1 SECTION 4.3
INFORMATION SOILS MAP SECTION 4.4
SOURCES TOPO MAP
NEEDED: DRAINAGE DETERMINATION
=" APPENDIX C LOCAL MATRIX QUALITY DATA APPENDIX A
SECTION 4.4
APPENDIX C
STREAM FLOW
PROPERTIES
SECTION 4.4
ACTIVITY:
CHARACTERIZE
WATERSHED
PROPERTIES
DETERMINE
INTEREST
SELECT
LDADIN9 MODEL(S)
ESTIMATE
PARAMETERS
CALCULATE
LOADS
EVALUATE LOADS
RELATIVE TO
HYDROL08IC
PARAMETERS
OUTPUTS
DESIRED:
LAND USE AREA
SLOPES
SLOPE LEN9THS
DRAINAGE DENSITY
SOIL TYPE
LAND USE ACTIVITIES
LAND USE/ACTIVITY
POLLUTANT MATRIX
MODEL(S)
LIST OF
MODEL
PARAMETERS
LAND USE/ACTIVITY
POLLUTANT LOAD
MATRIX
QUALITATIVE
ANALYSIS
TO WATER QUALITY IMPACT.
PROCEDURES
FIGURE 4-12
SCHEMATIC REPRESENTATION OF NPS LOAD ASSESSMENT METHODOLOGY
-------
4.5.2 Example Case Study
The methodology shown in Figure 4-12 will now- be illustrated such that the
"problem" defined above can be solved. Each step will be considered
separately.
Step I: The study area chosen is a hypothetical watershed located in central
Indiana, cleverly referred to as Indiana Creek Watershed. A schematic of the
watershed, complete with land uses noted, is given in Figure 4-13. Vital
statistics were obtained from the county and state Soil Conservation Service,
a recent land use survey, and standard USGS topographical maps. Analysis of
these data resulted in Table 4-25. Note that the slopes and soil types are
amazingly uniform.
Step II: The objective of step II is a listing of the potential pollutants
arising from the land uses and land use activities on the watershed. From
Tables 4-1 through 4-7, a new matrix was developed for Indiana Creek as shown
in Table 4-26. Additional information from water quality surveys suggests
nutrients and organics (BODj.) are the most serious problems .
D
Step III; Normally, specific loading models should only be selected after
careful consideration of the known water quality problems , analysis of the
available resources, and the importance (economic or political) of the
decision to be made with the resulting information. Such an effort should
never be taken lightly. Fortunately, the task in this case is straight-
forward. Loading functions developed by MRI which are based on equation (4-5)
will be used. Utilization of this approach permits desk-top calculations.
Equations- for each pollutant of interest in Table 4-26 are listed below.
Sediment, tons /year
3
Y(S)' = ZA.(RKLSCP). S, (4-8)
E i=1 i i d
Total Nitrogen, pounds/year
3
Y(NT) = Z a • Y(S) C (NT), r (4-9)
i=1 ti s IN
Available nitrogen, pounds/year
Y(NA) = f Y(NT) (4-10)
4-70
-------
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-------
TABLE 4-25
SUMMARY OF INDIANA CREEK WATERSHED PROPERTIES
Watershed Properties
Area, ac
Predominant slopes, \
Predominant slope
length, ft
Soil type
Total stream segment
length, mi
Land use activities
Cropland
280
6
300
Fayette silt
loam, 4%
organic matter
^.
Continuous
corn, contour
Land Use
Forest
450
15
120
Silt loam
-
Medium
stocked, 50%
1 Pasture
270
8
200
Fayette silt
loam, 4%
organic matter
-
80% ground
cover
Totals
1000
-
_
~
1.0
plowing,
conventional
tillage, yield
80-90 bu/ac,
residue left
tree canopy
cover, 80%
litter cover,
managed
undergrowth
TABLE 4-26
SUMMARY OF POTENTIAL POLLUTANTS
IN INDIANA CREEK DRAINAGE
Potential Pollutants
Land Use Activity
Cropland
Pasture
Forests
Sediment
X
X
X
Nitrogen
X
X
X
Phosphorus
X
X
X »
Organics
(BOD5)
X
X
X
Pesticides
X
4-72
-------
Total phosphorus, pounds/year
3
Y(PT) = E a • Y(S)E C (PT) rp
i=l i
Available phosphorus, pounds/year
Y(PA) = £p Y(PT)
Organic matter, pounds/year
3
Y(OM)
E a • Y (S)c C (OM) . rOM
= E s 1
BOD_, pounds/year
Y(BOD5) = £B Y(OM)
(4-11)
(4-12)
(4-13)
(4-14)
where
i
A
RKLSCP
N
>fP
V rP
rOM
CS(N),
cs(P),
CS(OM)
land use: cropland = 1, pasture = 2, forest = 3
land area for land use i, acres
factors of USLE, see equation (4-3)
sediment delivery ratio
availability constants for nitrogen, phosphorus, and
organic matter, expressed as fraction of total that is
available
enrichment ratios for nitrogen, phosphorus, and organic
matter
soil profile concentrations of nitrogen, phosphorus, and
organic matter, gin/100 gms
20
Of the pollutants listed in Table 4-26 for Indiana Creek, only pesticides were
omitted in the above list of loading functions. This in no way implies
pesticides are of no real concern and should be omitted. Rather, it reflects
current inability to adequately assess 'pesticides except at a rather detailed
level quite beyond the scope of this manual and, in particular, this example.
Also, none of the water quality impact analyses given in this manual include
pesticides. A more qualitative analysis of the pesticide problem will be
given in step VI.
4-73
-------
Step IV: Equations (4-8)through(4-14)contain a number of parameters that must
be estimated. Some represent properties of the entire watershed while others
are land use or pollutant specific. Each set of parameters will be selected
based on the material given in previous sections.
Sediment - The sediment delivery ratio is determined from Figure 4-7. Note
from Table 4-25 that the watershed has an area of 1000 acres (1.56 square
miles) and a stream length of 1.0 miles, yielding a drainage density of 0.64.
The inverse drainage density is 1.56. The soil type is silt loam which is
predominately silt. The resulting S, value from Figure 4-7 is 0.50. The R
value in equation(4-8)is common to the entire watershed and is estimated to be
175 as interpolated from Figure 4-4. The K value is also assumed constant for
the watershed since each land use has the same soil type and from Table 4-17
is estimated to be 0.33.
The remaining sediment-related parameters are land-use specific and are
estimated as follows:
Topographic factors from Figure 4-6:
Cropland - LS = 1.2
Pasture - LS = 1.4
Forest - LS = 2.8
Cover and Management factors, from Tables 4-18, 4-19, 4-20:
Cropland - C = 0.38
Pasture C = 0.013
Forest - C = 0.003
Erosion Control factors, from Table 4-21:
Cropland - P = 0.50
Pasture - P = 1.0
Forest - P = 1.0
Pollutants - The parameters associated with pollutants other than sediment are
included in equations (4-9) through (4-14). Assuming no local soil surveys,
appropriate values are abstracted from Figures 4-10 and 4-11, and Tables 4-24
and 4-25.
From Figures 4-10 and 4-11, the concentrations
-------
CS(NT)
Cs(PT)
CS(OM)
0.145% (mid-point of range)
0.032% (mid-point of range)
4.0% (from Table 4-25)
Note that C (OM) is based on the given soil characteristics and exceeds the
o
suggested value based on C (NT). A value of 20 times C (NT), or 2.9, would
^ o
result from the guidance in section 4.4.5
From section 4.4.5
N
0.06
0.10
No guidance was given on the relationship of BOD to organic matter so a value
of f = 0.06 was arbitrarily chosen.
B
From section 4.4.5
r,T = 2.0
OM
1.5
2.5
The summary of the selected model parameters for the Indiana Creek Watershed
is given in Table 4-27.
Step V: Calculation of loads require application of the parameters of Table
4-27 to equations (4-8 through 4-14)'. Calculations by land use are illustrated
as follows:
Cropland -
Y(NT)
Y(NA)
280 • 175 • 0.33 • 1.20 • 0.38 • 0.5 • 0.5
1843 tons/year
10,100 pounds/day, sediment
20 • 1843 • 0.145 • 2.0
10,689 pounds/year
29.3 pounds/day, total nitrogen
0.06 • 29.3
1.76 pounds/day, available nitrogen
4-75
-------
Parameter
Sd
R
K
LS
C
P
r
N
r
P
rOM
£
N
£
P
£B
TABLE 4-27
SUMMARY OF LOADING FUNCTION PARAMETERS
FOR INDIANA CREEK WATERSHED
Land Use
Cropland
0.5
175
0.33
1.20
, 0.38
0.50
0.145
0.032
4.0
2.0
1.5
2.5
0.06
0.10
0.06
Pasture
0.5
175
0.33
1.40
0.013
1.0
0.145
0.032
4.0
2.0
1.5
2.5
0.06
0.10
0.06
Forest
0.5
175
0.33
2.80
0.003
1.0
0.145
0.032
4.0
2.0
1.5
2.5
0.06
0.10
0.06
4-76
-------
Y(PT) = 20 • 1843 • 0.032* 1.5
= 1769 pounds/year
= 4.85 pounds/day, total phosphorus
Y(PA) =0.10 • 4.85
= 0.49 pounds/day, available phosphorus
Y(OM) = 20 ' 1843 * 4.0 ' 2.5
= 368,600 pounds/year
= 1010 pounds/day, organic matter
Y(BOD5) = 0.06 • 1010
=60.6 pounds/day, BOD_
Pastures - Similar calculations for pastures yield:
777 pounds/day
Y(NT) = 2.3 pounds/day
Y(NA) = 0.14 pounds/day
Y(PT) = 0.4 pounds/day
Y(PA) = 0.04 pounds /day
Y(OM) = 78 pounds/day
4.7 pounds/day
Forests - Finally for forests:
Y(S)E = 598 pounds/day
Y(NT) = 1.7 pounds/day
Y(NA) = 0.1 pounds/day
Y(PT) = 0.29 pounds/day
Y(PA) = 0.03 pounds/day
Y(OM) = 60 pounds/day
Y(BOD ) = 3.6 pounds/day
A summary of the results of the loading calculations are given in Table 4-28
using the land use-pollutant matrix format.
Step VI: The most meaningful way to predict NFS loads includes prediction of
runoff as the . transporting medium. The USLE-based loading functions only
implicitly include hydrology through the R value. Expansion of the assess-
ment procedure in this chapter to include a quantitative representation of
4-77
-------
TABLE 4-28
SUMMARY OF POLLUTANT LOADINGS
FOR INDIANA CREEK WATERSHED
Pollutants, Ib/day
Land Use Activity
Cropland
Pasture
Forest
Total Loading
Organic
Nitrogen Phosphorus Mattej^_
Total Available Total Available Total BODr
Sediment
10,100 29.3
777 2.3
598 1.7
ll',475 33.3
1.76
0.14
0.10
2.00
4.9
0.4
0.3
5.6
0.49 1010 60.6
0.04 78 4.7
0.03 60 3.6
0.56 1148 68.9
4-78
-------
the watershed hydrology would require a quantum jump in both effort and
sophistication. Such an effort is recommended as a mandatory step in any
comprehensive analysis, but is not included here.
A qualitative analysis of the watershed hydrology can be accomplished within
the ground rules assumed by this manual and is helpful in evaluating the
timing and potential impacts of selected pollutants. Recall from section
4.4.5 that the MRI loading functions can be used to predict the time-distri-
buted load by one of two methods. First, assume all equation factors remain
constant except for R and the loads are linearly distributed in time as a
function of R. Second, allow the R value to be weighted according to the
time-varying cover conditions represented by C. The R-distributed and
the RC-distributed curves are given in Figures 4-8 and 4-9, respectivelyt
The superposition of time-varying land use activities, watershed system
inputs, and streamflow characteristics on Figure 4-9 provides a qualitative
assessment of the interaction of the major system components including the
hydrology. Such an analysis for purposes of general "enlightenment" of
planning agency personnel has been proposed (23) and will be
included here.
A stream-gaging station downstream of Indiana Creek Watershed was selected to
represent the hydrologic characteristics of the area. Long-term flow records
were abstracted from published flow data and plotted as the annual average
monthly distribution in percent of total annual value as shown by curve Q in
Figure 4-14. Curve RC is the same as that of Figure 4-9 but expressed as
percent of total annual. That is, each monthly value has been multiplied by
the number of days in that month. The Q curve requires some further
explanation. If the curve was generated from data taken in Indiana Creek,
the response would more directly trace the rainfall events imbedded in the RC
curves. Downstream, however,- the curves can interact as shown because of the
areal variability of rainfall and the extraction of water via evapotrans-
piration. Plotted beneath the two curves are the time "windows" during which
certain land use activities and man-dnduced inputs to the watershed occur.
Only the cropland system is represented because the RC curve was calculated
4-79
-------
3 40
_)
$ 35
_)
g 30
< 25
_1
^ 20
O *5
£ .0
It)
O
£ ^
Q.
CORK
I I I I I I I I I I I
JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC JAN
r r
TP PL CULT
L EGEND:
TP - TURN PLOWING
PL - PLANT
CULT - CULTIVATION
HAR - HARVEST
P - PESTICIDE APPLICATION
F - FERTILIZER APPLICATION
FIGURE 4-14
INTERRELATION OF NON-POINT SOURCE
LAND USE AND HYDROLOGIC TRENDS
4-80
-------
using the cropland data. If forestry activities were included a longer
time period would be more appropriate.
Note from Figure 4-14 that during the period from May 15 to August 15
several watershed operations occur that can interact to produce nonpoint
source loads. The soil surface is essentially bare during a time of highly
erosive rainstorms (denoted by RC curve) and relativey low stream flow.
Also, the addition of potential pollutants (fertilizers and pesticides)
occurs during the same time period. In addition to an evaluation of
potential loads, Figure 4-14 suggests time during which field measurements
of stream water quality will be most meaningful.
4.6 Specific Nonurban, Nonpoint Source Category Information
As discussed in earlier sections, nonpoint sources of pollutants include
nonurban land use activities such as construction, agriculture (including
irrigation return flows), silviculture, hydrologic modifications, mining,
and residual management practices. In this section of the manual, these
specific source categories are discussed individually. The primary
intent is to familiarize the planner with the nature of the NFS load-
generating potential of each category, the types of pollutants which can
be anticipated, and with control measures or management practices which
have been identified to be appropriate and which may be considered in
the planning process.
The discussion covers each of the categories broadly, and identifies
specific documents or publications which may be referred to by the planner
to develop the in-depth information and guidance which will be required
to address those NFS problems which are important in his planning area.
The primary reference publications for each NFS category include a series
of EPA documents, either published or to be released in the near future.
These include:
(a) EPA Office of Research § Development Reports - These are guideline
manuals which provide technical information relating to specific
land use categories or types of activity.
(b) EPA 304(e) Documents - These provide general information and
4-81
-------
background on identification of NPS pollution and on potential
control measures.
(c) EPA Water Planning Division - This set of documents is presently
being issued. Separate manuals for each NPS category address the
Best Management Practices (BMP) which have been identified as
pertinent to that category. They are designed to assist the planner
interface effectively with technical specialists in identifying and
assessing the significance of NPS problems from various categories.
BMP documents will cover agriculture, silviculture, construction,
hydrologic modifications, mining and residuals management.
These sources of information, along with numerous other reported studies,
yield a valuable data base for continuing analysis and implementation of
control programs. The discussion provided in the balance of this chapter,
together with both the cited references and the secondary references which
can be developed from their review, can provide the planner with a starting
point and the framework for a planning effort appropriate to his study
area, for addressing NPS pollutants that are significant in his area.
4.6.1 Agriculture (Excluding Irrigated Agriculture)
Nonpoint source pollutant problems resulting from agricultural activities are
difficult to reduce to a simple set of specific sources, loads, controls, and
implementation. Problems arise because of the pervasiveness of activities
within watersheds; the almost infinite array of activities/practices
possible; the changes in practices which can usually occur annually; and
the diversity of chemicals, application rates, and methods available to
individual producers. The conjunctive use of agricultural lands for crop
production and disposal (or utilization) of animal wastes is yet another
spectrum of activities having potential for loadings which require a specific
set of controls. These'factors exist, unfortunately, in addition to the
normal variations associated with the hydrologic system described in Section
4.2.2
4.6.1.1 Activities and Practices
The control of nonpoint source pollutant loadings is different from control
of point sources in one key way - control is obtained only through source
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management and cannot be achieved by only knowledge of effluents (runoff).
This fact requires the analyst to become familiar with each land use
activity before any realistic problem assessment or subsequent control pro-
gram can be developed. Comprehensive analysis requires a definition of
activities more detailed than those in Table 4-3. No complete description
of each activity for each crop and for every part of the country exists.
Several reports are available, however, that describe cultural systems for
specific crops (36-39). These references, in addition to local information
available from state universities, provide excellent overviews of the
mechanics for specific agricultural crop production. For example, references
on wheat production describe the nature and timing of field operations,
fertilizer and pesticide application recommendations, compatible rotations,
etc., in use where.wheat is grown.
4.6.1.2 Pollutants
The knowledge of the use and scheduling of these activities permits an
evaluation of pollutant-generating practices, the delineation of pollutants,
and most importantly, an insight into feasible management practices for
control. The advantages of having a general knowledge of agricultural
production are considerable when implementation of controls is desired.
Certain activities are common to all crops and can be considered collectively.
Most notable among these (related to nonpoint source pollutants) is the
application of fertilizers and pesticides. Several references are available
that give detailed descriptions of pesticide properties, intended use,
toxicity data, persistence, and relative mobility in soils (40).
Similarly, fertilizer technology and evnironmental behavior has been reviewed
in recent publications (41, 42). Some of these references are production-
oriented, but the basic data give useful insights to potential problems
and their control.
Data for the distribution of various crops throughout the country and the
associated planting and harvesting dates have been compiled and reported
in-a USDA Handbook (43). Listings by crop and geographical areas are
included. The resulting time "windows" for planting and harvesting also
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suggest times when chemical applications are made and pollutant-loading
analyses, similar to that illustrated by Figure 4-14, can be completed.
More comprehensive analyses (e.g., via ARM, ACTMO) also require information
of this type.
In addition to crop production management, agricultural waste management is
an activity which is requiring more attention as semi-confined and concentra-
ted livestock and poultry feeding increases. In some situations these waste
sources are technically (and legally) considered to be point sources of
pollution and, therefore, subject to the appropriate point source discharge
permit regulations. Point source controls notwithstanding agricultural
lands remain the ultimate recipient of solid and liquid wastes and nonpoint
source load potentials must be evaluated. Two key EPA reports, now in
preparation and soon to be published, describe livestock operations, wastes
generated, and available controls (44, 45). -
4.6.1.3 Control Practices
Chapter 4 has thus far been devoted to a discussion of NPS loading assessment.
However, the specification of needed controls is the ultimate objective of
a loading assessment. One of the most complete and useful source of
information currently available for the selection of agricultural pollution
controls is the two-volume report jointly prepared by the USDA and EPA
referred to several times previously (2, 4). This manual points out controls
available for erosion, runoff, nutrients, and pesticides. A methodology
for selection of control practices, complete with flow charts and examples,
is given in Volume I. A detailed interpretive review of existing literature
is given in Volume II. These volumes are complete, have been designed
specifically for use in development of nonpoint source control plans, and
represent the state-of-the-art for agricultural sources. They are recommend-
ed for use in the development of water quality management planning.
Similarly, the manuals for agricultural waste management, which are being
prepared (44, 45) have been specifically designed to facilitate their use
in environmental planning and decision-making.
Additional references (11, 13, 14, 15, 16, 20, 27, 32, 35) potentially use-
ful in problem assessment, selection of controls, and implementation of plans
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have been previously discussed and will not be addressed here.
4.6.2 Silviculture
The major differences between agricultural and silvicultural activities are
their frequency and areal extent within a given watershed. An agricultural
rotation can extend from one to five years, while silviculture cycles
are keyed to tree growth and extend from 20 to 80 years. Land use activi-
ties impacting nonpoint source loading, therefore, occur over relatively
short time periods followed by a much longer recovery period. For example,
clear-cutting to remove vegetation is a drastic change in the watershed,
but recovery (if proper management steps are taken) is relatively rapid.
4.6.2.1 Activities and Practices
The broad categories suggested in Section 4.2.1.2 apply to silvicultural
systems nation-wide. The U.S. Forest Service has further defined these
activities in a joint Forest Service-EPA report (46). The major activities
are categorized and defined as follows:
1. Vegetative manipulation by mechanical means: Any activity (excluding
timber harvest and road construction) that uses mechanized equipment
to alter or remove vegetation is included in this category. Mechani-
cal site preparation for reforestation after timber harvest or for
species type conversion is the most significant operation. Because
such practices are somewhat limited by ground slopes, the most wide-
spread use of these techniques is in the 'lower elevations common to
the southern and southeastern United States. Dissmeyer (47) has
described several treatments including chopping; chopping and burning;
chopping, burning, and bedding; KG-blading; windrowing and burning;
KG-blading, windrowing, burning, and bedding; and bulldozing, wind-
rowing and burning. The area subjected to these treatments varies
widely and depends on the size of cut or extent of type conversion
desired.
2. Road and trail construction and maintenance: Access systems are a
necessary part of any timber harvest system and include a variety of
permanent roads, spur roads, skid trails, and landings. Some are
continually maintained, while others are returned to natural vegetation
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after harvest is complete. The pollutants most characteristic of silvi-
culture activities are those associated with road construction and mainte-
nance. The EPA-FS report cited previously (46) is an excellent overview.
3. Fire: Fire management systems include the use of fires for undergrowth
control, slash disposal, and wildifire control. Wildfire itself can
expose vast areas to erosive and leaching processes.
4. Grazing: Although not a silvicultural activity, grazing may constitute a
major land use within timber areas. The pollutants are similar to those
in agricultural activities.
5. Timber harvest: Only those activities directly associated with cutting
and removal of trees are considered here. Access roads and reforestation*
integral parts of harvesting operations, have been discussed separately.
Various harvesting systems, extent of areal disturbance, and pollutants
have been described (48, 49).
6. Recreation: Multiple use of forest lands is a common practice on public
lands. Camping, recreational travel, fishing, and hunting can result in
problems ranging from waste disposal to site maintenance.
7. Chemical use: Intensive timber management often includes applications of
fertilizers and pesticides. Forest fertilization of established tree
stands is a growing practice in northwest and southwest. Although less is
known about pesticide usage, both insecticides and herbicides are used.
A recent review of silviculture chemicals usage in the northwest is
available (50).
4.6.2.2 Pollutants
The major impact exerted on the forested watershed results from the exposure
of soil surface to erosive and leaching processes. The major pollutant (by
volume) is sediment. Some operations, particularly timber harvest, increase
water yield, accelerate oxidation of organic matter, and result in increased
levels of plant nutrient discharge. The most comprehensive review of these
problems and a description of the available data for each is included in the
EPA-FS report (46).
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4.6.2.3 Control Practices
Control of pollutants generated by silviculture is achieved through source
management. A comprehensive selection methodology for controls is being
developed. Several reports (46, 48, 51) describe control measures and
further elaborate on specific activities listed above.
4.6.3 Construction
Construction activity is estimated to influence about 1 million acres (some-
what less than 0.2% of the total land area of the U.S.) at any one time.
This includes construction for housing, highways, dams, and the like. The
major pollutant resulting from construction is sediment. Although gross
yields are relatively small compared with other NFS categories because of the
smaller area .affected, site-specific loads can be high and localized adverse
impacts often result.
Several elements make control or reduction of pollutants from construction
activity more practical than from other NFS activities. This results from
(a) the relatively localized nature of the activity, (b) the on-site
concentration of men, facilities and equipment during the construction
process and (c) the ability to plan or modify specific activities in order
to minimize pollution potential.
Because the occurrence of runoff is a function of the local climatic events
which can be highly variable, pollutants from construction sites can change
drastically and unpredictably. Also, the nature and quantity of pollutants
depend upon the project phase, soil characteristics, local topography, and
geologic conditions, the magnitude of people and equipment involved, extent
of protective vegetative covering on the site, and other factors.
Control measures for this category will be directed at (a) minimizing
the generation of pollutants, and (b) minimizing the runoff at those which
are generated.
4.6.3.1 Activities and Practices
In analyzing the potential for the generation of pollutants from this
NFS category, it is useful to make a distinction between construction
activities, and construction practices. Activities are characterized in
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such a way that a distinction is made among (a) transportation and
communication networks, (b) housing, (c) energy networks (power plants
and transmission lines), (d) water resource development (dams, canals),
and (e) recreational developments (parks, ski slopes). Generally, all
will give rise to nonpoint pollution. However, basic differences in
area affected, proximity to water sources, and predominant construction
practices employed make it likely that specific problems and controls
will be more or less consistent within an activity and different from
other activities.
Construction practices may be defined as specific categories of job
operations - for example, clearing and grubbing, grading, construction
of facility, and site restoration. For any type of activity, each of
the practices have a particular potential for the generation of pollutants.
The potential for both the type of pollutant and the magnitude of the
load differ with the particular practice, so that this characterization
provides a useful frame of reference within which to assess pollutant
loads and control measures.
Construction practices refer to the individual jobs performed in a
construction project over a period of time. Each practice has a different
potential to produce pollutants.
Clearing, grubbing, and pest control are construction practices typical
in the first stage of a construction activity. During these operations
unwanted vegetation including trees, bushes and sod is removed from the
original site. In addition, herbicides may be applied to remove unwanted
vegetation from the area.
Rough grading is the next step in most construction projects. During
this phase the soil is moved from one place to another to obtain desired
surface elevations. Grading may involve cutting and filling of slopes
for highway projects, excavating or filling for buildings, or excavating
for pipeline or canal installations. Heavy machinery used in this
.practice can be responsible for creating substantial amounts of petroleum
waste products. In addition, the effects of moving and disturbing soils
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and subsoils can alter their physical characteristics to make them
easily eroded when impacted by rainfall.
Rough grading is followed by final grading and facility construction.
The constructed facility is different for transmission structures,
highways, buildings and dams, but it is at this time that all construction
sites encounter much physical activity. Equipment and machinery are in
use, products and materials are on the site and workers are the most
active. Pollutants generated during facility construction include
chemicals, trash, sanitary wastes, cement and trace metals.
The final construction practice is that of site restoration. This
includes cleanup of the site, final grading in some areas, tilling,
establishment of permanent vegetation, removal of temporary structures
and any other activities that restore the site to a balanced landscape.
It is principally at this time that fertilizers are applied and nutrient
runoff can be generated.
4.6.3.2 Pollutants
Sediment is the principal pollutant by weight that can result from
construction. During a precipitation event, soil particles are eroded,
transported, and deposited at other locations. Sediment may be deposited
on'land at the bottom of steep slopes or transported to a water body.
Once in the water body, the soil particles may be further transported to
areas of deposition where the stream velocity is less than that required
to keep the sediment particles in suspension.
Pesticides are another type of nonpoint source pollutant. They include
insecticides, herbicides, and rodenticides; These chemical compounds
may adhere to the soil particles or dissolve in the runoff water and be
transported off the construction site during runoff events.
Other nonpoint pollutants include petroleum products such as gasoline,
diesel fuel, oil, grease and solvents. Some oils are used for dust
control which requires that they be applied directly to the soil. These
products become pollutants through their general use and misuse on the
construction site.
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Other chemicals may be used on the construction project for site preparation,
facility construction, or for site restoration. Chemicals used to
develop desirable soil properties are lime, fly ash, asphalt, phosphoric
acid, salt and calcium chloride. Additional chemicals used during
construction include pastes, oils, paints, solvents, dying compounds,
cleaning compounds, and concrete curing compounds.
In addition, the construction site usually contains an excess of damaged
building products, packaging and other miscellaneous garbage. Garbage
can take the form of food containers, cans, coffee containers, empty
cigarette packs, and general refuse. 'If they are not collected, they
may eventually be transported to the nearest stream or water body.
Sanitary wastes are generated on construction sites by the work force.
This type of pollution is generally controlled by using portable facilities.
However, sanitary wastes may still reach the water bodies and be a
source of pathogenic organisms.
Metals are used extensively for most types of construction projects.
When pipes, beams, wire mesh etc., are left exposed to weather conditions,
they eventually oxidize. During precipiation events, surface runoff may
transport these oxides off the construction site to the stream.
Cement can become another source of water pollution if loose materials
are not stored in a dry location out of the weather. The most common
source of pollution from cement results from the washing of cement
transporting vehicles or batching facilities. This washing is generally
done in a batching plant area or where cement.is to be placed often
without regard for closeness to a stream.
Nitrogen and phosphorus compounds are used at construction sites for
fertilizers. Some of these compounds may adhere to soils-and can be
washed to adjacent streams during runoff events. In addition, nutrients
can dissolve in water and pollute both surface waters and groundwater.
4.6.3.3 Control Practices
Best Management Practices on a construction site are measures to control
erosion, sediment and stormwater runoff. Each method is designed to
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minimize the pollutants being transported off the site as a result of a
runoff event.
Erosion control measures prevent the transport of soil particles. These
practices reduce both energy and velocity of the runoff thereby reducing
its erosive powers. Erosion controls minimize soil exposure, control
runoff, shield the soil and bind the soil.
A method to reduce erosion is surface roughing of slopes. Roughing
includes tracking and scarification of slopes to slow the movement of
runoff. Diversion structures such as soil or stone dikes, ditches,
terraces and benches may also be used to control runoff by diverting
runoff from sensitive areas. When diversion structures are used they
may be used in conjunction with disposal structures which transport the
diverted runoff without causing further pollution. Disposal structures
include flexible downdrains, sectional downdrains, flumes, and level
spreaders.
Vegetation can also be used to reduce erosion by protecting the ground
surface from rainfall impact, binding the soil particles in place, and
filtering out sediment which may be transported. Temporary stabilization
is attained by planting fast growing annual and perennial plants, and
provides short-term protection during construction delays or until
permanent vegetation has become established. Permanent stabilization
involves the planting of permanent vegetative materials such as grasses,
legumes, vines, shrubs, native herbaceous plants, and trees.
Soil stabilization on a temporary and or permanent basis can also be
attained through the use of nonvegetative controls. Nonvegetative
temporary stabilization practices include the use of mulches, nettings
and chemical binders which hold the soil in place or protect it from
rainfall energy. More permanent controls include gravel slopes, retaining
structures, bank protection, and instream grade stabilization structures.
Control of pollution from construction sites also involves sediment
control. Sediment controls prevent sediment transport off the constuction
site. These controls include both filtering and ponding of runoff.
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Filtering of surface runoff can be effected by vegetation. Common
vegetative filters include natural buffer strips, installed buffer
strips, center strips, and soil inlet filters. These filters remove
sediment and debris from the runoff. The filters also slow the runoff
thereby reducing its erosive capability.
Structural devices often are used in sediment control to intercept and
detain runoff allowing the sediment to settle out, and to remove large
debris. Structural devices are designed for the lifetime of the construction
project or may be permanent and continue to operate after construction
is complete. These devices include gravel inlet filters, sediment
traps, and wet and dry sedimentation basins.
Although sediment is the major pollutant by weight generated as a
result of construction activity, the other pollutants discussed earlier
in the section must also be controlled. Partial control would be
accomplished through the use of sediment control practices identified in
this section. However, total removal of all other pollutants could be
attained only by appropriate wastewater treatment, and would be expensive.
The best methods to control these other pollutants are good housekeeping
practices. These practices are not expensive to implement, however,
they do require care and awareness by the workers, supervisors, engineers
and planners. These practices are discussed in detail in the literature
(16).
Good housekeeping practices involve the proper application of materials
such as nutrients and pesticides when necessary. They also include
proper disposal of solid and sanitary wastes. Finally, the construction
activity should use the most effective type and amount of materials and
properly dispose of the unused materials along with the other solid
wastes.
Although the need for controlling runoff from a construction site has
gained a degree of recognition, that of controlling excess runoff after
development has not been fully recognized. Replacing natural open
spaces by paved areas and buildings lowers the overall water infiltration
capacity of a site which, in turn, leads to increased stormwater runoff.
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When stormwater enters directly into a stream, the increased velocity
may cause accelerated erosion of the stream channel. Where this runoff
enters existing sewer systems, the .system capacity may not be adequate
to treat the increased flow and this could result in the discharge of
poorly treated or untreated wastewater to the stream.
Stormwater management methods provide means to controlling runoff,
reducing stream channel erosion and sediment discharge, and the release
of pollutants contained in the stormwater runoff. Among those methods
is the temporary storage and regulated release of runoff from small
storms.
The following is a list of typical stormwater management practices which
have been used in urban areas or on construction sites in non-urban
areas:
1. Roof Top Ponding
2. Parking Lot Ponding
3. Diversion Structures
4. Ponds
5. Retention Basins
6. Porous 'Pavement
7. Holding Tanks
8. Infiltration Systems
9. Stream Channel Storage and Control
10. In-Line Sewer Storage
The best water pollution abatement plan is one which minimizes or
prevents erosion, sediment and runoff damages. No one single management
practice can fulfill this task. An adequate water pollution abatement
plan will contain many of the control practices discussed in this section.
In addition, the best plans are based on a site inspection of the area
and a data evaluation. If evaluated early enough, a construction activity
or project may be adjusted or relocated depending on the sensitivity of
the area. Any plan evolved should include feedback to allow for adjustments
depending on the field activities.
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4.6.3.4 Annotated Bibliography
1. "Methods for Identifying and Evaluating the Nature and Extent
of Nonpoint Source Pollution," Environmental Protection Agency
Publication 430/9-73-014 (October 1973) (52).
This report includes a discussion of construction activities as one of
the major nonpoint sources of pollution significantly influenced by the
commercial activities of man.
Estimates are presented of the land area influenced and erosion rates
for construction relative to agriculture, silviculture and mining.
Significant pollutants likely to be contributed by each source are
discussed.
Approximately 30 pages, devoted to the discussion of construction as a
source of nonpoint pollution, provide a concise summary of types of
activities and types of practices which can influence the potential for
generating NPS loads, th'e type of pollutants and methods of pollutant
transport. The report distinguishes between construction activity and
construction practice. It characterizes five general classes of activity,
each of which could be expected to influence NPS load generation in a
different manner and possibly dictate different broad approaches to
problems. For any of the types of activity (e.g. housing, dams and
canals, etc.), a series of construction practices are identified and
their relation to NPS load generation are discussed. Potential pollutants
which could be generated from construction activities are identified and
their source and potential significance are discussed.
The section of this report dealing with construction can provide the 208
planner with a good overview and perspective on the potential for pollution
from construction activities.
2. "Processes, Procedures, and Methods to Control Pollution Resulting
from All Construction Activity," Environmental Protection Agency
Publication 430/9-73-007 (October 1973) (53).
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This report presents information on processes, procedures and methods
for controlling sediment, stormwater, and pollutants other than sediment
which result from construction activities. The processes examined
include site planning, preliminary site evaluation and design, use of
planning tools, and structural and vegetative design' considerations.
The procedures examined include relative processes at Federal, State and
local levels necessary to control land disturbing activities. Methods
discussed include on-site erosion sediment and stormwater management
control structures, as well as soil stabilization practices.
This report emphasizes planning as an essential element in the control
of nonpoint pollution originating from construction sites. A pollution
control plan should be an integral part of the project and should start
as early as the site selection. In addition, control of pollution as
well as the other engineering factors should control the timing of
certain construction activities. The project design should also include
plans to protect the environment, such as the installation of temporary
stream crossing structures prior to construction, proper disposal of
petroleum wastes, etc.
The major section of the text discusses the on-site methods which are
available for the control of erosion, sediment, and stormwater. Structural,
nonstructural and vegetative control techniques are addressed. Sketches
and photographs of a variety of pollution control devices are provided
although detailed design considerations are not covered. It provides a
useful introduction to the devices which are available and discusses how
these devices are*useful in the control of nonpoint pollution.
For the planner, this report will be useful for obtaining background
information on the processes and methods available to control nonpoint
pollution originating from construction activities. For an engineer, it
emphasizes the importance of the total site evaluation and planning
ideology, and can be used as a source of references to the more technical
manuals which are available.
3. EPA, Nonpoint Source Pollution Control Guidance Construction
Activity, (in Progress) (54).
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The objectives of this report, presently in draft form, are to identify
management practices which will reduce or control generation of pollutants
from construction activities, and to provide guidance to 208 planner in
evaluation or selecting measures which may be appropriate in this area.
The document contains four chapters. Chapter 1 discusses approaches to
identifying and assessing the existence of problems. The discussion is
general in nature and describes possible approaches. The approaches
discussed include:
(a) making a general survey of existing and recently completed
construction projects to determine the extent of pollution.
(b) examining water quality data (coincident with the construction
activity) to determine if the activity was harmful to the
waterbody.
This chapter also discusses the various physical observations which
should be made to help indicate whether significant erosion has taken
place. In addition, methods for making gross estimates of the quantity
of eroded soils are presented in this chapter.
Chapter 2 discusses the procedures which may be helpful to make an
analysis of the construction activity and its effect on the surrounding
water bodies. The section is brief and very general and primarily
identifies types of data which may be useful in the evaluation of nonpoint
runoff and control and the sources from which it may be procured.
Discussion of control approaches provides a broad overview, and essentially
identifies the principles to be considered.
Chapter 3 discusses several of the techniques available for the control
of erosion, sediment and stormwater. Erosion control practices include
both vegetative and structural devices. Vegetative control practices
are described in general terms while the engineering details are contained
in cited literature. As a guide for the design of erosion, sediment,
and stormwater control structures, some preliminary information and
sketches are given. In addition, the references necessary for a more
detailed examination and design of the control devices are presented in
the text. Using the Universal Soil Loss equation to estimate sediment
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runoff, the final section in this chapter estimates the amount of
sediment generated on a construction site after control devices have
been added. Also, estimates of the changes in the input parameters of
the soil loss equation with changes in control devices are made.
The thrust of Chapter 4 is a presentation of a methodology for the
assessment of potential pollution problems and their magnitude. Sediment
is the major pollutant addressed. Using the Universal Soil Loss Equation,
sediment losses from areas without control devices are estimated.
Charts and tables are presented to enable the users to calculate the
USLE input parameters. Finally, references are given throughout the
chapter directing the reader to more detailed information on the methodology.
This manual will assist both a nontechnical planner and an engineer in
assessing and evaluating pollutants which result from construction
activities. However, for a complete design or evaluation, it may be
necessary to augment this information with data that is presented in the
cited references.
4. "Comparative Costs for Erosion and Sediment Control, Construction
Activities," Environmental Protection Agency Report 430/9-73-016
(July 1973) (55).
This report presents installation costs for certain erosion and sediment
control,devices which may be used to minimize nonpoint runoff from
construction activities. This information is documented for more than
25 pollution control practices in current use in both the eastern and
western United States. Most of the data presented were obtained from
the Walnut Creek Watershed in central California and the Occoquan Watershed
in Virginia.
The report describes erosion and sediment control structures. It includes
photographs and sketches of the control structure being discussed.
Detailed installation cost data is provided for the particular control
devices.
Cost data is provided for the removal of sediment which originates at
construction sites and which has been translocated to a deposition point
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by rainfall runoff. Removal methods examined include excavation and
dredging. Limited data are presented for the cost of removing sediment
from runoff by water treatment.
The text also discusses the USLE as a method of estimating sediment
loss. All graphs and charts that are necessary to make quantitive
estimates of soil losses using the USLE are presented. The USLE is also
used to analyze the effectiveness of erosion and sediment structural and
nonstructural control measures.
The text includes a cost evaluation example problem which developed from
information presented in previous sections. The example problem gives
additional insight to the chapter since it shows the reader exactly what
input data is needed, how it is handled and processed and how the data
can be used to make performance-and cost effectiveness estimates.
The material presented in this report aids either an engineer or a
planner who knows what the NFS problem is and which control solutions
are available. This report will then help the engineer calculate the
cost and effectiveness of the given control structures or techniques.
An actual cost figure would require, an adjustment of the estimate through
one of the acceptable indices.
5. "Standards and Specifications for Soil Erosion and Sediment Control
in Developing Areas," U.S. Dept. of Agriculture, Soil Conservation
Service (56).
The report presents specifications for the design of erosion and sediment
control structures. The standards and specifications were prepared by
the Soil Conservation Service while providing technical assistance
through the Soil Conservation Districts in Maryland. A general background
to erosion phenomena and sediment control is presented in the report.
However, this presentation is short and should not replace the background
information on erosion, sediment and the respective control techniques
and procedures which are presented in other references discussed earlier.
The first section of the report is concerned with temporary structural
practices. The text defines the structural practices, gives the purpose,
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describes the condition where the practice applies, and lists the design
criteria and construction specifications. In addition, each structure
is illustrated with a standard engineering drawing which includes a copy
of the construction specifications. The drawing with the specifications
is useful in that it contains all the information necessary for a field
engineer or supervisor. The text also gives any of the mathematical
equations which are necessary for the structural design. If graphs or
nomographs are needed to solve the design equations, then they are also
presented.
The report then describes the standards and specifications for permanent
structural practices. Because these are permanent structures, their
design and their specifications receive more attention than did the
temporary structures. For most of the structures detailed hydraulic
considerations are included in the design. However, all equations,
nomographs and illustrations are included.
Vegetative control practices are discussed next and on the same level of
detail as both temporary and permanent structures. When applicable,
vegetative seeding procedures and the installation dates for certain
vegetative covers are given, as well as fertilizer application dates and
application rates.
Finally, standards and specifications for other nonstructural practices
as discussed. These activities include bank stabilization, topsoiling,
tree protection and other miscellaneous topics not covered in the earlier
sections.
It should be recognized that this is a highly technical manual, and is
less useful than some of the others cited in the planning stages of a
water pollution control project. In these early stages, the other more
general background literature, cost literature and effectiveness of
control literature should be consulted. The information in this manual
will be most useful when the proper control structure has been selected
and it is time to design the site specific structures and implement
their construction.
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4.6.4 Hydrologic Modification
Hydrologic modifications result from activities that alter the natural
flow patterns of surface and groundwater. Water quality impacts may be
realized from hydrologic modifications both during facility construction
and after the project is operational. The pollutant problems resulting
from the construction phase of the project are discussed in the section
on construction activities, Section 4.6.3, while the problems resulting
from the completed hydrologic modification are discussed below.
The various types of hydrologic moficiations which may already exist, or
may be proposed for a 208 planning area are identified and discussed in
this section. The different types of pollutants which may affect the
study area are presented, and various control strategies are analyzed.
An"annotated bibliography is also provided to> indicate more detailed
sources of information for the assessment of hydrologic modifications.
4.6.4.1 Activities and Practices
Hydrologic modifications can be grouped into channel modifications,
impoundments and reservoirs, dredging and other resource recovery operations
and water use systems. Channel modifications are generally for flood
control or for improved drainage, and they provide an increased channel
capacity. This allows for the passage of a greater volume of flow.
Flood control modifications include channel clearing and snagging,
channel excavations and channel realignment. Other modifications are
sometimes made to tributaries of the main channel for flood and stormwater
control. These include the construction of retarding basins and debris
basins. Modifications of the drainage pattern may be accomplished with
drainage ditches and surface or groundwater pumping.
A general result of channel modifications is an increase in stream
velocity. The velocity increase is caused by a decrease in the stream
roughness or by the straightening of the channel. However, the increased
velocity may sometimes exceed the channel stability velocity and will
cause bottom scour and bank erosion. In addition, when work is performed
in the stream channel, the stream shoreline is usually disturbed by the
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movement of equipment. During these construction activities, shoreline
vegetation may be removed or killed. The destruction of vegetation can
result in an increase in the incident solar radiation. This, in turn,
can result in an increase in stream temperature.
Hydrologic modifications which result in the depletion or lowering of
groundwaters can impair quality in both surface and subsurface waters.
Fish and wildlife habitats may be reduced from the increased infiltration
of stream waters, seasonal water temperature patterns may be modified,
and seawater intrusion may occur in coastal areas.
Impoundments are constructed for power generation, flood control and
water supply. Those impoundments used only for power generation are
known as run-of-the-river impoundments. Run-of-the-river impoundments
have a time of flow passage of approximately a few days or less and,
therefore, do not confine a large volume of water. Another type of
impoundment is a reservoir storage impoundment which can have a time of
flow passage of many months. These are the large reservoirs which are
used for water supply and flood control. These storage reservoirs often
result in significant water quality problems.
The depth of the large reservoirs combined with the incident solar
radiation usually creates thermal stratification of the water impounded
on the upstream side of the dam. The more common pollutional problems
downstream of the dam are caused by the release of water which is warmer
or colder than the downstream water temperature and the release of water
which is low in dissolved oxygen and supersaturated with nitrogen.
Instream resource recovery operations such as dredging are another type
of channel modification. These operations can cause nonpoint source
pollution when the extraction of the materials from the streambed is
taking place. If the benthos contains settled sewage or other waste
products, these pollutants may become resuspended during the dredging
operations. Additional problems can occur from the changes in bottom
substrates and biological habitats and alterations in water velocity and
current patterns.
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4.6.4.2 Pollutants
Sediment is normally generated during the construction of hydrologic
modifications. After the completion of the channel modifications it is
possible that an increased stream sediment content will also persist
because of the higher stream velocities that are present in the stream.
Sediment deposition may also be a problem at the upstream end of
impoundments: as the water flows into the impounded area, stream velocities
decrease and the suspended sediment may settle to the stream bed.
Instream water temperatures are affected by incident solar radiation
which reaches the stream if channel modifications remove or reduce the
natural vegetative covers. In addition, thermally stratified water
layers are created in reservoirs because of the incident solar radiation
and the depth of the water. Depending on the outlet point of the reservoir,
the thermal increases or decreases can occur in the downstream water
temperatures.
Other pollutants such as nutrients, herbicides, insecticides, trace
metals, other chemicals and soluble organic compounds, may exist in the
benthic muds. When the muds are disturbed, such as in dredging or other
channel alterations, these pollutants can be resuspended. In the case
of impoundments, the natural leaching processes can transport these
pollutants from the benthos to the water column.
4.6.4.3 Control Practices
Control practices to be followed during the construction phase of hydrologic
modifications are the same as those discussed in Section 4.6.3.3 for
general construction activity. Best management practices for channel
modifications attempt to reduce the erosive force of the stream flow.
Site preparation and reduction of thermal stratification are practices
which reduce the nonpoint source pollution for impoundments.
Best management practices for control of nonpoint source pollution
originating from channel modifications reduce the stream velocity and,
therefore, reduce its erosive forces. The velocity reduction may be
obtained by increasing the channel roughness or decreasing the channel
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slope. Rocks and stones (of local origin whenever possible) can be used
to increase channel roughness and/or stabilize banks. Riffle and pool
areas can also be built into the channel modifications to dissipate
energy and, additionally, provide areas of stream reaeration. If the
channel cross-sectional area is increased for flood control, a low-flow
channel should be provided within the new channel. This low-flow
channel can be constructed with the same physical characteristics as the
original channel. When major channel modifications are performed, the
bends in the river should be designed to prevent erosion of the banks.
The usual method for this is to have steep outside banks and shallow
inside banks. In addition, stones can be used on the outside banks to
protect them from erosion.
Temperature increases can be controlled by the proper planning of vegetative
cover. Whenever possible, natural vegetation should be left undisturbed
during construction. In addition, permanent vegetation should be planted
upon project completion to provide soil stabilization and shade cover
conditions similar to those which existed before construction.
Control of spoils removed from the channel is an additional measure
necessary to control nonpoint source pollution. These spoils are
usually placed along the side of the stream. They should be prevented
from returning to the river through erosion and runoff. This can be
accomplished through proper sloping and immediate revegetation. In
addition, spoils should be placed so they do not harm the natural vegetation.
Best management practices for control of nonpoint source pollution
originating from impoundments include proper site preparation, control
of release waters, minimization of stratification, and temporary algal
and weed controls. Soil areas within the impoundment should be prepared
for flooding. Lumber, stumps, and man-made debris should be removed
from the impoundment area. Grass, shrubs, organic mulches, and rich
topsoils should also be removed. Finally, the bed should be covered by
two inches or more of sand to prevent the leaching of materials out of
the soil.
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Outlets located at several levels can be used selectively to release
waters in which the temperature and dissolved oxygen are consistent with
downstream water quality. Conversely, thermal stratification in deep
reservoirs could be avoided by mixing the impounded water via diffusers or
other mechnaical means. Also, release waters could be reaerated mechanically
or by outfall design in order to prevent the discharge of water having a
dissolved oxygen deficiency.
In large impoundments, eutrophication may be a problem. The only control
practice which provides long-term results for eutrophication control is
to limit the nutrients entering the reservoir. Proper site preparation
will aid in nutrient reduction. However, the amount of nutrients reaching
the stream from upstream point and nonpoint sources can provide enough
nutrients to eutrophy an impounded area. These sources should be
controlled by point source nutrient removal processes and nonpoint
source nutrient control practices.
Temporary solutions to eutrophication problems are often used when long-
term solutions are not possible. Temporary solutions include harvesting
of algae, cutting and removal of aquatic weeds, drowning of aquatic
weeds and the use of herbicides.
4.6.4.4 Annotated Bibliography
1. "The Control of Pollution From Hydrographic Modifications,"
Environmental Protection Agency Publication -- EPA 430/9-73-017 (57).
This report presents a broad, general description of the environmental
effects of hydrographic modifications. (Note that the term "hydrographic
modification" is used instead of "hydrologic modification", although
their meanings are the same.) The preparation of the report was mandated
by Section 304(e) (1) and (2) part (F) of the Federal Water Pollution
Control Act Amendments of 1972, Public Law 92-500. Qualitative guidance
is provided for identifying and evaluating pollution problems and possible
control measures. Although quantitative, predictive methods are referenced,
none are described in the report. In this respect, "The Control of
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Pollution From Hydrographic Modifications" is well suited for an introductory
overview of the wide range of possible problems and solutions.
The report discusses four general types of hydrographic modifications.
These include:
1. Channel modification projects.
2. Impoundments and reservoirs.
3. Effects of urbanization.
4. Dredging operations.
For each type of project the current level of government involvement is
discussed, including the activities of Federal, State and local agencies.
Current practices are identified, as are the sources and types of pollutants
which may affect the modified waterway. Methods of pollutant transport
in stream channels and impoundments are examined, and water quality
modeling and data collection are briefly described. The mechanics of
groundwater pollution, such as that which occurs from seawater intrusion,
is also discussed.
Methods, processes and procedures to control the pollution impact of
projects are presented. Examples of these include design modifications
to minimize adverse channelization impacts, structural, and nonstructural
alternatives to channelization, aeration and destratification of reservoirs,
land use control, and productive uses of dredge spoil.
2. "Impact of Hydrologic Modifications on Water Quality," Environmental
Protection Agency Publication — EPA 600/2-75-007(1975) (58).
This report describes the scope and magnitude of water pollution problems
caused by hydrologic modification activities that disturb natural flow
patterns of surface water and groundwater. Although no new field
measurements were made, a large body of available data is analyzed and
presented.
The study has two principal purposes. The first is a description of the
magnitude of water quality problems caused by the following hydrologic
modifications:
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1. Construction
2. Dams and impoundments
3. Channelization
4. Dredging
5.^ Land reclamation activities.
Quantitative estimates are made of the amount of sediment that enters
the Nation's surface waters as a result of highway and urban construction.
This section has the format of a nationwide assessment, and is primarily
intended for use in EPA's program planning process. This analysis is
supplemented by an Appendix with numerous case studies from each of the
five categories of hydrologic modifications from around the United
States. These summaries constitute a useful and concise compilation of
extensive information and data.
The second purpose of the report is to develop "source loading functions!'
for predicting the quantities of water pollutants released by out-of-
stream construction activities. These loading functions can be used by
technical investigators to estimate the amount of sediment entering a
watercourse from construction sites of known size and locations. The
loading functions, which are adaptations of the USLE, are based on
measurements of sediment yields and other parameters at ten construction
sites. The accuracy and limitations of the functions are analyzed.
The report also includes a brief discussion of methods for controlling
pollution from hydrologic modifications, including out-of-stream and
instream approaches.
3. "EPA Nonpoint Pollution Control Guidance, Hydrologic Modifications,"
(in progress), Environmental Protection Agency, Water Planning
Division (59).
This document presents the information needed by a water quality management
or planning group in developing the management practices to minimize
water pollution due to hydrologic modifications. The report is directed
towards activities which modify the hydrology of an area, such as
channelization, dams, dredging, and instream construction; as well as
activities which unintentionally impact hydrologic characteristics, such
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as the land development which accompanies rapid urbanization. The
information is qualitative, and specifications for technical design are
not included.
The report describes approaches for assessing water quality problems
from existing hydrologic modifications. The different types of modifications
and the various pollutants which may effect them are discussed. These
pollutants include:
1. Sediment
2. Nutrients
3. Thermal effects
4. Pesticides and other chemicals.
5. Biological microorganisms.
Possible sources for available information are identified and survey
techniques for expanding the information are discussed.
Methods for the analysis and selection of control alternatives are also
presented. Data needs are described, including climatic, geologic and
topographic information. Selected practices for the control of water
quality problems associated with hydrologic modifications are discussed
in more detail.
The report includes a section on identifying potential problems from
proposed projects. Analyses were made of primary problems such as
flooding and landslides which could result from poor planning and
design and secondary problems such as sediment control during construction.
The Appendix of the report presents some of the pertinent rules and
regulations of the United States Army Corps of Engineers and the
Environmental Protection Agency related to hydrologic modifications.
They are reproduced from the Federal Register and include:
1. U.S. Army Corps of Engineers, "Permits for Activities in Navigable
Waters or Ocean Waters"
2. Environmental Protection Agency, "Navigable Water, Discharge
of Dredged or Fill Material"
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The Appendix is useful for determining the legal considerations that may
be involved in planning decisions.
4. "Report on Channel Modifications - The President's Council on
Environmental Quality, United States Government Printing Office,"
(March, 1972) (60).
This report, prepared for the Council on Environmental Quality discusses
forty-two selected channelization projects performed by the United
States Army Corps of Engineers, Soil Conservation Service, Tennessee
Valley Authority, and the Bureau of Reclamation. An assessment is made
of the environmental, economic, and engineering aspects of the channel
modifications. The methodology used in preparing this report is a good
guide for those evaluating additional projects.
The projects chosen for discussion represent a variety of climatic and
topographical conditions, soil type, aquatic and habitat systems, rural
and urban locale, and a range of project purposes and sizes. Each site
evaluation conducted by the study group consisted of a general project
briefing session, a field survey of the area, and a concluding session
with public participation.
Professional observations serve as a basis for evaluating the physical
effects of wetland drainage and land use changes, cutoff of oxbows and
meanders, watertable changes and stream recharge, erosion, sedimentation,
and channel maintenance. The results of extensive biological investigations
conducted by the Philadelphia Academy of Natural Sciences are presented.
These are integrated into a useful format for evaluating the effects of
channel modifications on fish and wildlife resources, habitat, species
diversity, and productivity. Although there is little quantitative
information presented based upon measurements of water quality or hydraulic
parameters, the assessment procedures derived from professional observation
and biological studies may be useful to the planner of additional projects.
5. "Planning and Design of Open Channels," United States Department
of Agriculture, Soil Conservation Service, Technical Release
No. 25, December, 1964, Revised March, 1973(61).
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This technical release is presented as a guide for use by field personnel
in the evaluation, planning, and design of open channels. The material
is directed toward the more complex type of channel work done by the
Soil Conservation Service. This includes floodways and drainage-type
channels in which channel degradation and bank erosion are of primary
concern.
The report discusses general planning considerations such as the adequacy
of outlets, legal requirements, and the rights-of-way. Guidance is
provided for the preliminary survey, drawings, strip maps, and profiles.
Examples of drawings are included.
Site investigations are described to evaluate the resistance of the
soils in the bed and banks of the channel to erosion forces, to evaluate
the sediment transport relationships, to determine slope stability
against sloughing and sliding, to estimate earth loads that may act on
structural members, and to determine the rate of water movement through
the soils. Information for identifying and analyzing stratigraphic
units (layers of soil) is presented, and procedures for sampling and
testing the channel bed and slope are suggested.
The report presents a methodology for determining channel capacity and
relating this to design discharges. Designs for special transition
structures in waterways are examined. Criteria for slope stability are
analyzed, and methods for improving channel slope stability are suggested.
The revised version of the report includes a section on environmental
considerations in channel design, installation, and maintenance. Although
no definitive criteria or standards are established for SCS projects,
useful guidance is provided for the planner. Issues of aesthetic quality,
fish, and recreation resources are addressed. Methods are presented for
protecting these beneficial uses through design and during construction.
The section on environmental considerations includes appendices with
approaches and charts for rating the recreational and environmental
quality of a project. The report provides useful technical information
for the actual design and implementation of channelization projects.
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6. "Water Quality Management Planning Methodology for Hydrographic
Modification Activities," Texas Water Quality Board, (December, 1976)(62).
This report, prepared for the Texas Water Quality Board, develops a
methodology for the evaluation of hydrographic modifications, the pollutant
loads generated by associated activities, impacts on receiving water
bodies, and pertinent control strategies. Although portions of the
report pertain specifically to conditions in Texas, the approach and
techniques presented are useful to planners seeking a straightforward
analysis framework for evaluating hydrographic modifications.
The effects of hydrographic modifications are outlined by examining
typical contaminants and relating them to instream impacts. These
impacts include:
1. Aesthetic value
2. Dissolved oxygen depletion
3. Sediments and deposits
4. Excessive aquatic growth
5. Public health threats
6. Improved recreation value
7. Ecological damage
8. Reduced commercial value.
Water quality problems common in impoundments and reservoirs are identified
and quantitative estimating techniques are presented. Issues of temperature,
density, stratification, evaporation, and eutrophication are addressed.
Solutions are given for pollutant concentrations in run-of-the-river
impoundments, large vertically mixed and vertically stratified reservoirs,
and two dimensional near-field effects. Simple, empirical methods for
relating the eutrophic status of a lake to the nutrient loads are discussed.
Example problems are included to demonstrate the techniques.
The pollution impact of channel modifications and dredging operations
are also presented. Some of the issues addressed are the relationship
between bank vegetation and water temperature, the effect on reactions,
reaeration and the assimilative capacity of the stream, and the physical,
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chemical, and biological characteristics of dredged material. Relevant
data needs and sources of information are discussed.
The report includes an analysis of pollution control methods for each
type of hydrographic modification activity. Examples of those presented
are site preparation, control of loads, selected withdrawals from reservoirs,
aeration and destratification, control of nuisance organisms, reclamation
of disturbed areas, and disposal site controls.
7. Reports from the United States Army Corps of Engineers.
A number of studies related to hydrologic modifcations have been conducted
by the U.S. Army Engineer Waterways Experiment Station in Vicksburg,
Mississippi. A few of the available reports are summarized below.
a. "Mathematical Simulation of the Turbidity Structure Within an
Impoundment," Research Report H-73-2 (63).
In this report, the thermal and turbidity structures of an impoundment
are simulated with a mathematical model. The model was verified with
observed data from the Hills Creek Reservoir in Oregon and used to
predict the turbidity structure of a proposed impoundment. The effectiveness
of selective withdrawal, in particular, a low-level outlet for controlling
turbidity is examined. Examples of input and output from the computer
program used for the analysis are presented.
•
b. "Selective Withdrawal from Man-Made Lakes," Technical Report
H-73-4 (64).
This report presents the results of laboratory investigations to determine
the withdrawal-zone characteristics created in a density-stratified
impoundment by releasing flow through a submerged orifice, over a free
and submerged weir, or through a combination of the above. Density
stratification from differentials in both temperature and salinity are
examined. Generalized relationships for describing the vertical limits
of the withdrawal zone and the vertical velocity distribution within the
zone are developed. This flow rate distribution can then be applied as
a weighting function to the reservoir profile of water quality parameters
to determine their,concentrations in the reservoir release.
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c. "Ecological Evaluation of Proposed Discharge of Dredged or Fill
Material into Navigable Waters," Miscellaneous Paper D-76-17 (65).
This document is intended to provide interim guidance for the evaluation
of discharges of dredged material as mandated in Section 404 (b) of
Public Law 92-500. The selection and interpretation of appropriate
tests for dredging sites and dredged material are discussed. General
approaches for technical evaluation are partitioned into physical effects,
chemical-biological interactive effects, and procedures for site comparison.
The report presents detailed stepwise procedures for conducting an
elutriation test (to simulate the release of dissolved solids from
dredged material), estimating a mixing zone, performing bioassays, conducting
total sediment analyses, and evaluating biological community structure.
d. "Techniques for Reducing Turbidity Associated with Present
Dredging Procedures and Operations," Contract Report 0-76-4(66).
The reduction of turbidity from present dredging procedures is examined
by analyzing the following operations: Cutter performance, ladder,
suction, hull, pipeline, connections, barges, tenders, personnel, inspection,
contracts, plans, and specifications. The suggested techniques consist
principally of good dredging procedures already known, but not always
followed by dredging contractors and their personnel.
e. "B. Everett Jordon Lake Water Quality Study," Technical Report
H-76-3(67).
This report is an example of a study on a large impoundment. Physical
and mathematical models are used to investigate the hydrodynamics of
stratified flow within the lake, to predict the temperature and dissolved
oxygen regimes of the lake immediately upstream of the dam, and to
estimate the temperatures and dissolved oxygen content of the release.
The report provides an interesting example of applications of different
modeling techniques used by the Army Corps of Engineers.
4.6.5 Mining
Mining refers to the extraction, transport, processing and storage of
minerals and disposal of mineral wastes. Mining activities impact more
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than ten million acres of land in the United States. The types and
quantities of pollutants generated from these mining operations are
dependent on the substance being mined, rock type, climate, topography,
geologic structure, method of mining, and hydrologic characteristics of
the site. The detrimental effects of mining activities can be prevented,
reduced, or eliminated by preventing the formation of pollutants at the
mine site, containing the pollutants within the mining area once they
are generated, and controlling pollutant contributions emanating from
mining operation areas.
4.6.5.1 Activities and Practices
The extraction of mineral deposits from the earth is accomplished by
surface mining, underground mining, well extraction, and a number of
lesser methods including in-situ leaching.
Surface mining takes several forms such as strip, open pit, dredging,
and hydraulic mining. Strip mining involves the removal of overburden
to expose an underlying deposit for extraction. Open pit mining is a
similar procedure for areas with little overburden. Open pit mines
contribute minimal spoil, but result in deep open holes. Dredging is
underwater mineral recovery. The material may be removed from artificial
impoundments or natural bodies of water. Hydraulic mining incorporates
the use of a high velocity water jet directed at unconsolidated deposits.
Underground mining is directed at the extraction of minerals deep in the
earth. Shafts are sunk to gain access to the deposit. Surface mining
generally creates a more visible defacement and disturbance of the
earth's surface than does underground mining. The placement and distribution
of the mineral deposit determines the size, depth and method of the
mining operation.
A mining operation progresses along a number stages of development
including exploration; access and support facility construction; mineral
extraction and processing; mine closure; mineral storage; and waste
disposal.
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4.6.5.2 Pollutants
Both surface and groundwaters can be adversely affected by active and
inactive or abandoned mining operations. Pollution arises because
hydrologic characteristics of surface or subsurface runoff may be altered
when the earth is disturbed to gain access to mineral deposits. The
degree of alteration and pollution generated depends upon the size,
depth, and method of the disturbance and also on the chemical and physical
properties of the disturbed material.
The major forms of water, pollution resulting from mining operations
include physical, chemical, and hydrologic changes. Most chemical
pollution results from the oxidation of sulfide minerals. In the presence
of water and an increased amount of oxygen due to exposure, accelerated
oxidation of the ore may produce, acid and salts, particularly iron salts
and sulfuric acid. When these solutions contact mineral and soil formations,
the acid may in turn selectively extract heavy metals.
Refuse waste materials that result from mining activities can be significant
sources of pollution when surface or groundwater percolation is intercepted
and produces a contaminated leachate. In addition, mineral wastes which
contain pyrite will oxidize and form soluble iron salts and sulfuric
acid. These may be flushed into nearb^ surface waters or percolate into
groundwaters during a precipitation event.
Radioactivity arising from mining activities is primarily a concern in
the western United States with regard to seepage of uranium and radium
at sites where uranium ores are mined and processed. The effects of
very long term exposure to low levels of radioactivity are of concern
and are being studied.
The most common form of physical pollution is sediment. Surface mining
creates large areas of disturbed land which are often highly credible.
The processing of raw minerals to concentrate ore creates vast piles of
fine grained waste materials which are a potential source of sediment
pollution. During contour strip mining operations, the practice of
placing overburden on the downslope side of the outcrop can result in
excessive siltation in water courses.
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In summary, the most serious pollutants associated with mining and
mineral operations are mine drainage contaminants and sediment.- Mine
drainage contaminants may include such constituents as acids, alkalis,
iron, aluminum, manganese, zinc, cobalt, lead, mercury, cyanide, fluoride,
copper, arsenic, cadmium, nickel, phosphate, sulfate, chloride, and
radioactive mineral contaminants.
4.6.5.3 Control Practices
Mine water pollution control is generally achieved by preventing pollution
production or containing pollutants on the mine site and controlling
pollutant delivery to the receiving water. For both surface and underground
mining, effective pollution control pre-planning can prevent, reduce or
eliminate pollution from active mining areas and pollution that may
occur after completion of mining. Such site characteristics as geology
and ground water patterns, climate, soil and slope stability, chemical/
physical nature of the overburden, past mining history and characteristics
of receiving waters should thoroughly be investigated to determine the
proper choice of mining methods and pollution control techniques.
4.6.5.3.1 Surface Mining - On-site Abatement
a. Controlled Mining Procedures: Certain mining procedures provide
better control of water pollution than other techniques. The adaptation
of one or more of the techniques is governed by the specific type of
mining operation. Some of the controlled mining procedures are discussed
below.
Overburden can be separated by type. Some overburden materials are
conducive to plant life, while others are sterile or have the potential
for polluting. The purpose of overburden segregation is to keep these
classes of material separated during mining so they can be effectively
utilized during later regrading.
Longwall strip mining is being researched as an alternative to conventional
strip mining as a procedure which may reduce the pollution potential of
the mining operations. A vertical trench is cut into a hill perpendicular
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to the mineral outcrop and the deposit is extracted with automatic
mining equipment. There is little surface disturbance required when
using this technique and most of the sediment related problems of strip
mining are eliminated.
Other mining techniques in use are modified block cut, head-of-hollow
fill, box-cut mining, area mining, auger mining, and selective mineral
extraction. Any of these mining operations may result in more or less
noripoint pollution, depending on the characteristics of the particular
site.
b. Water Infiltration Control: Infiltration results from subsurface
water movements, or downward percolation of surface waters from rainfall.
Pollution from water infiltration can be avoided by decreasing surface
permeability, using impermeable barriers between the water source and
the pollution forming material, diversion of water around the mine site,
and underdrain utilization.
c. Handling Pollution-Forming Materials: Pollution-forming mining
wastes discarded on the land surface may be exposed to oxidation, weathering,
erosion and leaching. Mine backfilling and sealing, relocation of
wastes to a more suitable hydrologic location, and flooding of underground
mines to eliminate oxidation are several methods of controlling pollution
from these materials.
Another technique is the utilization of mine wastes as saleable products.
Reprocessing mine wastes for secondary extraction can eliminate or
reduce waste piles.
d. Regrading: Regrading is the mass movement of earth to achieve a
more desirable topography. The main purpose of regrading is to provide
a suitable base for revegetation, burial of wastes, and reduction of
erosion. The techniques will vary according to the topography of the
final land surface.
e. Erosion Control: Erosion control is accomplished by several basic
methods. One of these is the protection of erodible surfaces from
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movement by water. This is accomplished by water diversion and by
covering procedures. Chemical stabilization, revegetation, mulching,
slope control, and concentrated flow handling are methods of decreasing
erosion potential at mine sites. Revegetation, specifically, is one of
the most effective erosion control techniques. A dense ground cover
stabilizes the surface with its root system, shields the surface from
rainfall, and reduces velocity of surface runoff.
4.6.5.3.2 Underground Mining - On-site Abatement
a. Controlled Mining Procedures: For underground mining, water pollutants
are generated after mining is completed by oxidation of the mined materials.
Air circulating through an abandoned mine can therefore continue to
oxidize susceptible materials. Flooding of a mine to exclude air is the
only practical method of eliminating this source of oxygen under present
technology. However, if a mine is flooded, the flooded water must be
contained within the mine or it can itself become a source of pollution.
Most of the water entering underground mines passes vertically through
the mine roof from overlying strata. Collapse of a mine roof is sometimes
responsible for increased vertical flow. The chance of the collapse of
overlying strata can be reduced by employing one or a combination of the
following: pillars, roof support, limiting the width of openings, and
by backfilling the voids.
b. Water Infiltration Control: These techniques are designed to reduce
the amount of water entering underground mines, and subsequently to
reduce the amount of drainage leaving the mine. Choice of techniques
and extent of their use will depend on hydrologic conditions in the area
and cost effectiveness of each technique. Infiltration generally occurs
as a result of rainfall recharge to the ground water reservoir. Rock
fracture zones and faults have strong influence on ground water flow
patterns. Infiltration can usually be reduced by avoiding these zones
during mining. Boreholes and other fractures can be sealed up to reduce
the movement of water.
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Filling surface depressions, smoothing overlying areas, or other surface
regrading techniques can be used to decrease water infiltration.
c. Mine Sealing: This practice is usually employed to promote inundation
of underground mine workings in order to reduce oxidation of pyritic
materials. Mine sealing involves construction of a physical barrier in
a mine opening to prevent passage of air and water. A mine seal can be
constructed in many ways, using many different types of material. A
mine seal must have internal strength capable of withstanding water
pressure, and it must be tied into the floor, roof, and sides of a mine
opening. Some seal types and methods which have been successfully
demonstrated include double bulkheads, gunite, grout curtains, clay and
air seals.
4.6.5.4 Annotated Bibliography (Mining Activity)
1. U.S. Environmental Protection Agency, "Methods for Identifying and
Evaluating the Nature and Extent of Nonpoint Sources of Pollutants,"
EPA 430/9-73-014 Washington, D.C., (October 1973) (68).
This report provides documentation of presently available knowledge in
four areas of nonpoint sources of discharge, namely, agriculture,
silviculture, mining and construction. In the seventy-page chapter on
mining, the nature and extent of pollution from mining activities is
discussed, data interpretation aids are given and prediction methods
pertaining to pollution sources from mining are presented.
The report discusses the nature of the sources, the type and relative
importance of pollutants from each source, and the pollution loads
related to natural and operational factors. General discussions on acid
mine drainage, sediment, leachate, and radioactivity are included.
Discussions are given on groundwater pollution and subsidence from
abandoned underground mines. Details of some coal mine drainage pollution
problems are presented. Pollution sources 'from other mining activities
discussed in less detail include the mining of hard rock minerals;
stone, sand and gravel; noncoal sedimentary materials; and oil and gas.
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Statistical information on inactive and abandoned mines, and sources of
current statistics on active mining operations are also provided.
The empirical aids for mine drainage data interpretation that are presented
in the report consist of nomographs which permit a check of the anion-
cation balance of a sample. The use of the nomographs and interpretation
of the results obtained from them are discussed, as is the conversion of
raw water quality data into useful form. Trends (correlations) that
were observed for stream quality data in mine drainage areas are also
presented. A discussion of sampling techniques and procedures, and
analytical methods that are usually performed for mining-related wastewater,
is presented. Brief descriptions of models that have been developed for
predicting pollution quantities are also presented together with indications
of their applicability and success. These include models to determine
flow and chemical characteristics of mine drainage, limestone requirements
for pyritic spoils and overburden, infiltration of water into spoil
banks, leachate quantities from spoil banks, pollution potential from
spent oil shale, mine drainage volumes in localized areas, and sediment
loadings.
This report presents a general overview of information to identify and
evaluate the extent of nonpoint sources of pollutants stemming from
mining activities. The reader may use this information as a guide to
more elaborate and comprehensive discussions of the previously mentioned
i
topics relating to mining activities. A list of seventy references are
presented at the end of the raining section of this report and are footnoted
in appropriate sections of the text.
2. U.S. Environmental Protection Agency, "Processes, Procedures and
Methods to Control Pollution from Mining Activities," EPA-430/9-73-
011, Washington, D.C.,(October 1972) (69).
This report provides information that identifies and evaluates available
technology for control of water pollution from mining activities.
Information is presented on techniques of at-source water pollution
control applicable to the mining industry, whose practicability and
feasibility have been demonstrated, or strongly indicated by the results
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of research. The control methods included in this manual are identified
and described by way of brief text, generalized illustrations, and unit
cost indications where possible.
The manual is divided into three major components, namely, surface
mining, underground mining, and treatment of mine drainage. Discussions
of various controlled mining procedures, methods to control water
infiltration, and techniques used to handle polluted mine waters are
presented for surface mining and underground mining operations. The
section on surface mining also contains methods of handling pollution
forming materials, discussions of various types of regra'ding, erosion
control procedures, and revegetation techniques. Numerous methods of
mine sealing underground mines are also presented. The treatment section
of the report discusses neutralization of mine drainage utilizing various
limestone and lime processes. Subsections under treatment of mine
drainage include discussions on sludge disposal, evaporation processes,
reverse osmosis, electrodialysis, ion exchange processes, freezing
(crystallization), and iron oxidation.
The manual serves to acquaint the reader with the many available techniques
to control pollution from mining activities. It does not provide the
degree of detail that would be needed for it to be used alone as a
pollution control reference. However, the manual may be used to guide
the reader to the appropriate reference or references for specific,
detailed, comprehensive information on how to apply a particular technique.
3. EPA Technology Transfer Seminar Publication, "Erosion and Sediment
Control, Surface Mining in the Eastern U.S.," Volume I: Planning,
Volume II: Design, EPA-625/3-76-006,(October 1976} (70).
This manual consists of two volumes. Volume I covers the basic concepts
of erosion and sediment control and implementation of the control plan.
Volume II discusses design and construction considerations, erosion
control materials, and provides a sample of an erosion and sediment
control plan.
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The mechanics of soil erosion and sedimentation and the physical factors
which determine the nature and extent of these processes are discussed
in Volume I. Included are presentations of the methods of erosion and
sediment control and maintenance of control practices. The various
aspects of an erosion and sediment control plan and implementation of
this plan are also discussed.
Volume II of this manual discusses the design procedures and construction
specifications for selected control structures. Included are diversion
structures, sediment traps, downdrain structures, level spreaders,
grassed waterways, ripraps, check dams and sediment basins. Erosion
control products and materials, such as chemical binders, mulches, and
other stabilization materials are also discussed. A sample of an erosion
and sediment control plan, selected state mining laws, and reclamation
information are also presented.
This manual contains comprehensive discussions of various aspects of
erosion and sediment control. Volume I provides numerous figures and
photographs which aid the reader in obtaining a thorough explanation of
the need for control, basic control principles, available technology for
erosion and sediment control, and procedures for preparing and implementing
a control plan. -Similarly, Volume II is a detailed design manual,
containing numerous tables and figures of design parameters and construction
specifications for various control structures. Example problems and a
sediment basin design example are also included. The manual provides
lists of references after various sections, as well as a glossary. It
should be noted that the control information presented is directed
primarily toward preventing excessive soil loss and resulting damage
associated with coal surface mining operations in the eastern portion of
the United States, specifically the Appalachian, eastern interior, and
western interior coal regions. However, much of the material and certainly
all of the basic erosion and sediment control philosophy are applicable
to all categories of surface mining in all regions of the country.
4. "EPA Guidance for Identification and Assessment of Mining Nonpoint
Pollution Problems" (in Progress)(71).
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The problem assessment procedures that are presented in this document
are intended to help state and areawide 208 agencies to better understand
and carry out their planning responsibilities specifically related to
mining nonpoint sources under Public Law 92-500. This guidance presents
a simplified approach for planners to use in making an initial identification
of mining nonpoint source problems and suggests alternative judgements
and decision points that are involved in the definition of mining planning
requirements. The document suggests a task outline for identification
and assessment of mining nonpoint sources and provides procedures for
chosing the location and description of mining pollution, interpretation
of water quality data, existing pollution load description, quantitative
load characterization, and mining pollution load analysis.
5. Bituminous Coal Research, Inc., Mine Drainage Abstracts (72).
These abstracts are an important information source regarding what has
been published in the area of mine drainage research and in treatment
and control technology. Annual supplements published each year contain
information received that year pertaining to all aspects of mine drainage.
The bibliography and supplements are available at a nominal cost from
the Library, Bituminous Coal Research, Inc., 350 Hochberg Road, Monroeville,
Pennsylvania 15146.
4.6.6 Residuals Management Practices
Residuals management practices deal with the disposal of residual waste
materials. Residual waste materials are generally considered to be but
are not limited to wastewater treatment plant sludges, septage effluent
and pumpage, water treatment sludges, municipal refuse, combustion and
air pollution control residuals, industrial waste sludges, feedlot
manure, mining wastes, and dredge spoils. The residuals management
practices vary widely depending on the residuals and the land area.
4.6.6.1 Activities and Practices
Residual management can be separated into utilization practices and
disposal practices. The utilization practices are designed to reduce
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the amount of residual by conversion to a resource. Disposal practices
are strictly designed to dispose of the residual waste products.
Residual utilizations differ for each of the types of residuals. Wastewater
and water treatment plant sludges can be used for fertilizers and soil
conditioners after they are stabilized and dewatered. In addition, the
lime and alum can be removed from these sludges and reused. Municipal
refuse may be either recycled, or incinerated for use as an energy
source. A common use of combustion and air pollution control residuals
is for coarse aggregate material used in roadbed construction. There
are numerous recovery methods and uses for industrial waste sludges.
Each reuse depends directly on the characteristics of the sludge and
therefore on the industrial product. Finally, mining wastes can be used
for road construction materials or for incinerator combustion materials.
Disposal practices for residual wastes are diverse and in some cases,
complex. Each practice generally includes the operations of site selection,
evaluation, disposal, control and monitoring. The disposal operations
are categorized as land reclamation, land spreading, sanitary landfills,
ocean disposal, and trench disposal< Any single disposal method can not
normally be used for all of the previously cited residuals.
Land reclamation includes the reuse of strip mines and marginal lands,
and the creation of wildlife habitats. In each of these practices,
residuals are deposited on land through spray irrigation, pipeline
slurries, and hopper scows. These practices are generally used for the
residuals listed below.
1. Wastewater sludge
2. Septage
3. Water treatment sludge
4. Feedlot wastes
5. Dredge spoils
A second residual disposal practice is land spreading. Land spreading
is normally accomplished by spray irrigation, ridge and furrow application,
plow-furrow-cover application, plow-injection application, subsoil
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injection, truck application and manure spreading. These operations are
used for the liquid slurry residuals listed below.
1. Wastewater sludge
2. Septage
3. Feedlot wastes
4. Dredge spoils
Another residual disposal practice is sanitary landfilling. In sanitary
landfill operations, residuals are applied to the land, compacted,
covered with soil and compacted again. This process is repeated until
the landfill is completed. The landfill is closely monitored to insure
that both the groundwater and surface water are not contaminated by
leachate. Generally, municipal refuse comprises the largest fraction of
residual in a sanitary landfill. A landfill can accept sewage, septage
and water treatment sludges if proper pretreatment and dewatering is
practiced. Sanitary landfills are often used for disposal of combustion
air pollution control residuals and incineration residuals. Industrial
wastes and sludges are usually deposited in separate areas of the sanitary
landfill, while mixing, feedlot and dredging residuals are not normally
disposed of in sanitary landfills.
Ocean disposal is another residual management practice although operations
of this type are being significantly restricted. This practice has been
utilized extensively in the past for disposal of all types of residuals.
However, recent legeslation limits the mixed concentration of the residual
and water to 0.01 of the concentration which is detrimental to the
appropriate sensitive marine organisms. This will tend to eliminate
ocean disposal of all residuals except dredge spoils.
Trench disposal is another land application method. Residual wastes are
placed in trenches approximately two feet deep. The trench is then
immediately covered with soil to prevent odor escape and surface water
contamination. The only residuals which have normally been disposed of
in this manner are digested and raw dewatered sludges. Trench disposal
is not a commonly used method, since the period required for stabilization
may be as long as five years.
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4.6.6.2 Pollutants
Pollutants generated from residual management practices vary according
to the practice employed and the residual itself. The pollutants have
been listed in Table 4-5 according to the residual waste product.
Nitrogen and phosphorus are potential pollutants which originate in
wastewater sludge, septage, and feedlot manure. Organic materials are
generally derived from septage, water treatment, municipal refuse,
feedlot and dredge spoil residuals. Potential sources of heavy metals
are wastewater sludge, septage, water treatment sludge and municipal
refuse. Micro-organisms originate from all biological residuals.
To assess the pollutants from these residual management practices, the
planner must examine the residual. Next, he must examine the method of
disposal. Finally, he must examine the control practices used in the
site to monitor the possible pollution of surface and groundwater. It
is not likely that the quality or the quantity of the pollutants can be
assessed without site specific water quality data. However, these data
normally exist for some of the residuals management practices in the
planning area.
4.6.6.3 Control Practices
Residuals managment is practiced to dispose of residual waste materials
while at the same time eliminating and minimizing one of the nonpoint
sources of pollution.
The first step in a management plan is to minimize the volume of waste
material for disposal. A second requirement is the treatment of the
residual to the state-of-the-art treatment "level available. Such treatment
methods include stabilization, dewatering, neutralizing, etc.
Examination of the disposal site is required. The site should be chosen
so that the residual waste does not become a source of pollution upon
disposal. For example, an industrial sludge containing heavy metals
should not be used to fertilize a corn field. Likewise, salt water
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dredge spoils should not be applied to land as fertilizers due to their
high salt content.
It is during the site planning that the meteorologic, geologic, and
hydrologic characteristics of the disposal site should be examined. In
developing a disposal plan, disposal site conditions should be compatible
with the properties of the residual in order to give maximum protection
to both the ground water and surface water.
For a sanitary landfill, pollution control practices should include the
installation of proper drainage systems to divert surface water away
from the fill area. An impermeable liner can also be installed to
protect the groundwater. Additional control measures depend largely
upon the specific waste under consideration.
Other general management practices for pollution control of residuals
will depend on the residual and the conditions of the disposal site.
These methodologies are not described here. However, the many pollution
controls options for the residual management practices are available in
the literature.
4.6.6.4 Annotated Bibliography
1. "Effects of Land Disposal of Solid Wastes on Water Quality,"
Department of Health, Education, and Welfare, SW-Z, Bureau of
Solid Waste Management, Cincinnati,(1968) (73).
This pamphlet is an informative review of current literature which
describes the influence of solid waste disposal practices on water quality.
Definitions, site descriptions, water quality criteria, potential hazards,
case histories, recommendations, and tentative guides are included. The
information is designed to give some insight into the problems that may
occur and the methods for solving them.
A section describing open dumping and sanitary landfill as major land
disposal methods is presented. Included are discussions of infiltration
and percolation, solid wastes decomposition processes, gas production and
movement, leaching, groundwater travel and direct runoff, and the role
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each plays in contributing to surface and groundwater pollution due to
land disposal.
Evidence that physical characteristics, biological quality, and chemical
composition of surrounding waters are affected by quality and quantity
of solid waste conditions is well known. The physical characteristics
of major concern are turbidity, odor, taste, and color. Biological
water quality refers to bacteria present in the water, usually by leaching.
Chemical composition is concerned with mineral and organic substances
present in solid wastes which are capable of causing gross pollution of
underground water supplies. Of major concern are chlorides, organic
matter, hydrogen sulfide, carbon dioxide, methane, ammonia, and nitrates.
Case studies of water quality investigations related to solid waste
disposal operations are presented. These case histories are samples of
past investigations and some present research efforts presented to
clarify the potential pollution problem associated with refuse disposal
sites.
Requirements for proper land disposal are presented. Recommended land
disposal methods for surface water wet areas such as swamps and marshes,
tidal areas, ponds, quarries, and similar depression type areas are
discussed. Actual requirements enforced in several municipalities are
outlined.
In addition to requirements, suggested guides to enable management to
judge the acceptability of a waste disposal site are listed. These
include the areas of study required prior to design and construction of
sanitary landfills. Also included is a listing of guides to good practices
which is essentially a list of "DO's" and "DON'T's" with regard to land
disposal practices.
2. "Residual Management by Land Disposal," Procedings of the Hazardous
Waste Research Symposium, EPA Report No. 600/9-76-015, Cincinnati,
(July 1976) (74)'.
The report contains information on extramural research projects funded
by the Solid and Hazardous Waste Research Division of the U.S. Environmental
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Protection Agency, Municipal Research Laboratory in Cincinnati, Ohio.
The papers presented in the proceedings are separated into five sections,
as 'they were categorized in the symposium.
The first section, "Introduction and Orientation" presents an overview
of Federal research and legislative development programs for hazardous
waste disposal.
The. second section, "Identification of Pollution Potential" deals with
techniques for gathering and interpreting information about problems
with disposal of hazardous wastes. The authors indicate that there is a
need for a program of disposal research. They also describe some of the
methods used to observe the effects of land disposal of hazardous wastes
on environmental quality.
Available techniques for dealing with potential disposal problems are
presented in the third section, entitled "Modification of Disposal Sites
and Waste Streams." Chemical stabilization of the waste or soil and/or
use' of impermeable liners in order to prevent groundwater contamination
• are. .discussed.
The fourth section, "Special Disposal Problems," is a discussion of
problems encountered in disposal of specific types of wastes. The
wastes are highly concentrated and/or highly toxic substances such as
hexachlorobenzene, vinyl chloride, and pesticides.
Movement of contaminants in soil is discussed in the fifth section,
"Predicting Trace Element Migration." The section includes discussions
of predictive and modeling procedures, techniques and problems of detecting
contaminant movement, and determination of the soil properties and
contaminant characteristics which control movement.
3. Solid Waste Management: D. Joseph Hagerty, Joseph L. Pavoni, John
E. Heer, Jr.; Van Nostrand Reinhold Environmental Engineering
Series, (1973) (75).
The book offers a look at the environmental problems and solutions
associated with solid waste collection and disposal. Included are data
which show how future systems for collection, disposal, and recovery
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will have to be designed and selected. In addition, discussions are
included regarding the pros and cons of presently used systems, innovations
in collection equipment, and specialized practices and facilities for
transport and collection of solid waste.
Equipment is described which is capable of being modified to specific
ways of handling almost any type of solid waste. The many types of
compaction and size reduction equipment are discussed. Presentations of
separation techniques and material and energy recovery systems are
included. Ways and means to reduce the volume to be collected while
recovering larger amounts of highly valuable materials are shown.
Recovery of valuable materials is an incentive to the pursuit of
environmental goals.
In its discussion of sanitary landfills, the book includes information
on the design and planning stages, equipment requirments, site selection
considerations, relative costs of landfilling, prevention of resulting
pollutional problems, and use of the completed sanitary landfill.
A discussion of incineration is also included. The basic process principles
are discussed, and information is given regarding the planning, design',
construction, and operation of refuse incinerators and their accessory
apparatus.
The authors outline the economic advantages, environmental aspects, and
other factors involved with the new developments and equipment in the
field of solid waste management. Discussions of high-temperature
incineration, power generation through incineration, pyrolysis of wastes,
new landfill stabilization techniques, and landfill disposal of hazardous
wastes are included. Finally, the text outlines the legal, environmental,
and public relations aspects of solid wastes management.
4. "Management of Hazardous and Toxic Wastes," Paul N. Cheremisinoff,
William F. Holcomb, Pollution Engineering, Vol. 8 No. 4, April
1976, pp. 24-32 (76).
Hazardous wastes continue to be a significant problem, even as air and
water pollution control and solid waste disposal methods progress. The
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authors point out that the generation rate of non-radioactive hazardous
wastes is estimated in excess of 10 million tons annually and increasing,
or about 10 percent of all waste material generated by industry.
Included are several definitions of "hazardous wastes" as given by The
Hazardous 'Materials Transportation Act of 1974, Federal Water Pollution
Control Act Amendments of 1972, and the National Solid Wastes Management
Association. The authors also indicate that .disposal of wastes on land
is essentially unregulated except in the case of radioactive wastes.
The EPA is in favor of a program which would establish a nationwide
Federal and State regulatory program.
An extensive discussion of present disposal practices is included. In
making use of existing technology, hazardous wastes can be generally
dealt with by reduction in quantity generated by process modification or
raw materials changes; by concentration of wastes at the source by
evaporation, precipitation, etc.; by stimulation of waste exchange —
recovered acid, caustic, or solvent wastes may be sold or recycled; by
recovery and recycle of metals, energy content and other useful resources
contained in the wastes; by destruction of some hazardous wastes by
special incineration methods; by detoxification and neutralization for
land disposal; and by construction of specially designed landfills,
insulated from groundwater, and properly monitored and secured.
Finally, a section on "International Disposal Techniques for Other-than-
high-level Solid Radioactive Wastes" is presented. In the section,
disposal methods such as shallow land burial, disposal into mines and
deep geological formations, deep sea disposal, deep well disposal, and
packaging are discussed.
5. "Stop Leachate Problems," Michael Dilaj, John F. Lenard, Water and
Wastes Engineering, Volume 12 No. 10, October 1975, pp 27-40(77).
Controlling leachates is one of the most important aspects of sanitary
landfilling. The degradation of surface and groundwaters as a consequence
of landfill operations remains a problem, especially in humid areas
where precipitation is considerable.
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The authors visualize leaching as a special case of extraction of substances
adsorbed onto solid particles. The transfer of pollutants from the •
refuse to the groundwater is accomplished by vertically or horizontally
moving water which directly passes through, and has intimate contact
with the refuse.
Leaching takes place only if a section of the landfill is at saturation,
or field capacity. Any additional moisture beyond field capacity generates
leachate. Landfills containing large amounts of paper can retain significant
quantities of water without any leachate formation.
The authors discuss the type of information required prior to design of
the landfill. Subsurface characteristics of the site, including geologic
and hydrologic -patterns are required. Well studies, borings, and soil
surveys provide the data for design. From the data, water table contour
maps, cross-sections of the landfill site, groundwater flow patterns,
soil transmissibility, groundwater velocities, and infiltration capabilities
are determined.
Further discussion of each of the aforementioned developments is presented.
Finally, a case history design of a sanitary landfill in Ledyard, Connecticut
is discussed. The methods described in the article were used in the
design.
6. The Report to Congress: Waste Disposal Practices and Their Effects
on Groundwater, Executive Summary, U.S. Environmental Protection
Agency, Office of Water Supply, Office of Solid Waste Management
Programs, April 22, 1976 (78).
The report is a summary of an investigation into (a) disposal of waste
(including residential waste) which may endanger underground water which
supplies, or can reasonably be expected to supply, any public water
systems, and (b) means of control of such waste disposal.
The study covers waste disposal activities which result in the actual
collection and disposal of liquid, semi-solid, and solid wastes. In
addition, resulting contaminants from the disposal practices are defined
and their various routes to the groundwater system are outlined. Some
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of the wastes studied are industrial wastes contained in surface impoundments,
municipal and industrial refuse and sludge, septic tank and cesspool
wastes, municipal sewage, stormwater runoff, waste brine from petroleum
industry, solid and liquid mixing wastes, and animal feedlot wastes.
The report is divided into fifteen sections. The first three sections
are concerned with the importance of groundwater as a resource, its
nature and extent, and the ways in which it becomes contaminated. The
following nine sections of the report are concerned with common waste
disposal practices. The disposal practices are discussed in conjunction
with the types of wastes discussed in the preceding paragraph. The next
section discusses contamination of groundwater due to sources other than
waste disposal practices. The final two sections of the report are
concerned with existing federal legislation with regard to groundwater
contamination and discussions of state and local alternatives for
groundwater quality protection.
7,8. Solid Waste Disposal, Volume 1: Incineration and Landfill and
Volume 2: Reuse/Recycle and Pyrolysis, Baum, B. and Parker, C.,
Ann Arbor Science Publishers, Inc., Ann Arbor, Michigan, Vol. 1
1973, Vol. 2 1974(79).
Volume 1 of this book provides valuable information through a detailed
examination of two methods for the disposition and disposal of solid
wastes. The practice of incineration is treated in terms of its history
and its design criteria for both municipal and industrial wastes, capital .
and operations costs, instrumentation and control of air pollutants.
Landfill practices and the design, construction, administration, and
economics of sanitary landfill operation are discussed.
Volume 2 explores the vital aspects of reuse, recycling and reclamation
of plastic and non-plastic solid waste, with particular emphasis on ways
to preserve our natural resources, reduce pollution, conserve energy and
reduce costs. Finally, the authors analyze government activity and
legislation in this area and project into the future of solid waste
management and utilization, including a discussion of the latest disposal
methods..
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Recovery of solid' waste now represents less than 5% of total solids
disposed of by homes, industry, commerce and government. The importance
of this 2-volume study is that it not only surveys current problems and
methods of solid waste disposal, but also presents solutions that can
play a significant role in protecting and preserving our environment.
9. "Disposal of Sewage Sludge into a Sanitary Landfill," Report No.
SW-71d, U.S. Environmental Protection Agency(1974) (80).
This report describes the results of a three-year investigation of the
environmental and economic effects of disposing liquid sewage sludge and
septic tank pumpings into a sanitary landfill. The objectives of the
study were to determine: (1) the capacity of solid waste to assimilate
the moisture in liquid sewage sludge and septic tank pumpings; (2) the
significant parameters affecting that capacity; (3) the optimum means
for nuisance-free admixture of liquid sludge with solid waste in a
landfill; (4) the effects of combined liquid sludge-solid waste disposal
on the environment, landfill equipment, operating efficiencies, and
personnel performance; (5) the effects of liquid sludge on landfill
compaction and solid waste decomposition; and (6) the most economically
feasible methods for dewatering, transporting, and disposing liquid
sludge.
The three-year study included laboratory evaluations of water absorption
by solid waste, pilot-scale simulation of landfill conditions, full-scale
field test cells for controlled landfill simulation, full-scale demonstration
of liquid sewage sludge disposal into a sanitary landfill, and
characterization of the sewage sludges and solid wastes generated by the
City of Oceanside. A special nationwide survey of the disposal of
sewage sludge and septic tank pumpings into sanitary landfills was made
by contacting responsible State public health authorities and municipal
landfill managers.
10."Residual Waste Best Management Practices: A Water Planner's Guide
to Land Disposal/'Environmental Protection Agency Publication,
EPA-440/9-76-022 (in progress)(81).
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This handbook describes residual wastes from nine most frequently
encountered sources and relates management of these wastes to exhaustive
enumeration of Best Management Practices. The solid waste problem
assessment procedures that are presented in this report will provide the
potential users-planners, engineers, administrators, lawyers, elected
officials, and others with a reference for carrying out their residual
waste management responsibilities under areawide or state water quality
management planning programs and other regional and local activities.
Suggestions are presented, for the identification and assessment of
residual wastes nonpoint sources and methods are given for the location
and description of pollution associated with solid waste disposal. Also
included are methods of interpretation of water quality data and description
and characterization of loads associated with disposal of solid wastes.
4.7 References
1. "Predicting Rainfall Erosion Losses from Cropland East.of the Rocky
Mountains," Wischmeir, Smith, Department of Agriculture Publication
Handbook 282 (1965).
2. "Control of Water Pollution From Cropland - Volume I: A Manual for
Guideline Development," Stewart, Woolhiser, Wischmeir, Caro, Frere',
Environmental Protection Agency Publication EPA-600/2-75-026a
(November 1975).
3. "The Structure of Inputs and Outputs of Hydrologic Systems," Yevjevich,
In: Systems Approach to Hydrology, Water Resources Publications,
Colorado State University, Ft. Collins (1971).
4. "Control of Water Pollution from Cropland-Volume II: An Overview,"
Stewart, Woolhiser, Environmental Protection Agency Publication
EPA-600/2-76-026b (1977, at press).
5. "Precipitation Network Requirements for Streamflow Estimation,"
Johanson, Technical Report No. 147, Department of Civil Engineering,
Stanford University (August 1971).
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6. "Area-Depth Rainfall Formulas," Court, Journal of Geophysical Research,
Vol. 66, No. 6 (June 1961).
7. "Accuracy-of Estimating Watershed Mean Rainfall," McGuinness, Journal
of Geophysical Research, Vol. 68, No. 16 (August 1963).
8. "Sampling Errors in Measurement of Mean Precipitation," Huff, Journal
of Applied Meterology, Vol. 9 (February 1970).
9. "On The Transformation of Point Rainfall to Areal Rainfall," Iturbe-
Rodriguez, Mejia, Water Resources Research, Vol. 10, No. 4 (August 1974)
10. "Modeling Pesticides and Nutrients on Agricultural Lands," Donigian,
Crawford, Environmental Protection Agency Publication EPA-600/2-76-043
(February 1976).
11. "ACTMO, An Agricultural Chemical Transport Model," Frere, Onstad,
Holtan, Department of Agriculture, Agricultural Research Service
Publication ARS-H-3 (June 1975).
12. "Handbook of Applied Hydrology," Chow (editor), McGraw-Hill (1964).
13. "The Influence of Land Use on Stream Nutrient Levels," Omernik,
Environmental Protection Agency Publication EPA-600/3-76-014 (January
1976).
14. "Stochastic Approaches to Water Resources," Shen (editor), Colorado
State University, Ft. Collins (1976).
15. "Loading Functions for Assessment of Water Pollution from Nonpoint
Sources," McElroy, Chiu, Nebgen, Alleti, Bennett, Environmental
Protection Agency Publication EPA-600/2-76-151 (May 1976).
16. "USDAHL-74 Revised Model of Watershed Hydrology," Holtan, Stiltner,
Henson, Lopez, Department of Agriculture, Agricultural Research Service
Tech. Bull. No. 1518 (December 1975).
17. "Use and Misuse of the Universal Soil Loss Equation," Wischmeier,
Journal of Soil and Water Conservation (January/February 1976).
18. "Rainfall Energy and Its Relationship to Soil Loss," Wischmeir, Smith,
Trans. Amer. Geophys.' Union, Vol, 39, No. 2 (1958).
4-135
-------
19. "Effect o:f Land Use on Sediment Delivery Ratios," Mutchler, Bowie,
Proceedings of the Third Federal Inter-Agency Sedimentation Conference,
Water Resources Council (May 1976).
• r r
20. "Modeling Nonpoint;Pollution From the Land Surface," Donigian, Crawford,
Environmental Protection Agency Publication, EPA-600/3-76-083 (July
1976).
21. "Urban Stprm Water Runoff, "STORM"," Hydrologic Engineering Center,
Army Corps of Engineers at Davis (August 1975).
22. "Draft Report on Nonpoint Source Assessment" Ohio River Basin
Sanitation Commission, (1976).
23. "Nonpoint Source Pollution and the 208 Planning Process," Mulkey,
Report to the Environmental Protection Agency's Water Planning Division,
Athens (January 1976).
24. "Chemical Composition of Acid Precipitation in Central Texas," Cooper,
Demo, Lopez, Proceedings of the First International Symposium on Acid
Precipitation and Forest Ecosystem, Department of Agriculture, Forest
Service General Tech. Report NE-23, pp. 281-291.
25. "Nutrient Content of Precipitation Over Iowa," Tabatabai, Laflen,
Proceedings of the First International Symposium on Acid Precipitation
and the Forest Ecosystem, Department of Agriculture, Forest Service
General Tech. Report NE-23, pp. 293-308.
26. "The Chemical Composition of Atmospheric Precipitation From Selected
Stations in Michigan," Richardson, Merva, Proceedings of the First
International Symposium on Acid Precipitation and the Forest Ecosystem,
Department of Agriculture, Forest Service General Tech. Report NE-23,
pp. 321-332.
27. "Surface Runoff Losses of Soluble Nitrogen and Phosphorus Under Two
Systems of Soil Management," Klausner, Zwerman, Ellis, Journal of
Environmental Analysis, 3(1):42-46 (January/March 1974).
28. "The History and Character of Acid Precipitation in Eastern North
America," Cogbill, Proceedings of the First International Symposium
4-136
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on Acid Precipitation and the Forest Ecosystem, Department of Agriculture,
Forest Service General Tech. Report NE-23, pp. 363-370.
29. "The Variability of pH in Convective Storms," Semonin, Proceedings of
the First International Symposium on Acid Precipitation and the Forest
Ecosystem, Department of Agriculture, Forest Service General Tech.
Report NE-23, pp. 349-361.
30. "Losses of Fertilizers and Pesticides From Claypan Soils," Smith, Whitaker,
Heineman, Environmental Protection Agency Publication EPA-660/2-74-068
(1974).
31. "Transport, Detoxification, Fate, and Effects of Pesticides in Soil and
Water Environments," Leonard, Bailey, Swank, Land Application of Waste
Materials, Soil Conservation Society of America, pp. 48-78 (1976).
32. "Quantification of Pollutants in Agricultural Runoff," Dornbush, Anderson,
Harms, Environmental Protection Agency Publication EPA-600/2-74-005
(February 1974).
33. "Physical and Chemical Characteristics of Sediments Originating From
Missouri Valley Loess," Schuman, Piest, Spomer, Proceedings of the Third
Federal Inter-Agency Sedimentation Conference, pp. 3/28-3/40 (1976).
34. "Pesticide Concentration and Yields in Runoff and Sediment From a
Mississippi Delta Watershed," Willis, McDowell, Parr, Murphree, Proceed-
ings of the Third Federal Inter-Agency Sedimentation Conference, pp.
3/53-3/64 (1976).
35. "Agricultural Watershed Runoff Model for the Iowa-Cedar River Basins,"
Roesner, Report for Environmental Protection Agency's Systems Development
Branch (November 1975).
36. "Oats and Oat Improvement," American Society of Agronomy Monograph
8 (1961).
37. "Wheat and Wheat Improvement," American Society of Agronomy Monograph
13,(1967).
38. "Alfalfa Science and Technology," American Society of Agronomy Monograph
15, (1972).
4-137
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39. "Soybeans: Improvement, Production, and Uses," American Society of
Agronomy Monograph 16, (1973).
40. "Pesticides in Soil and Water," American Society of Agronomy Monograph,
16, (1973).
41. "Changing Patterns in Fertilizer Use," Soil Science Society of America,
Proceedings of a Symposium Sponsored by the Soil Science Society of
America, (February 1968).
42. "Fertilizer Technology and Use," Olson, Army, Hanway, Kilmer (editors),
Proceedings of the Symposium on "Fertilizer Technology and Use,"
Sponsored by the Soil Science Society of America,(December 1971).
43. "Usual Planting and Harvesting Dates," Burkhead, Max, Karnes, Reid,
Department of Agriculture, Statistical Reporting Service, Agriculture
Handbook No. 283 (March 1972).
44. "Animal Residue Utilization on Cropland and Pasture - A Manual for
Evaluation and Guideline Development," Environmental Protection Agency
and Department of Agriculture, Agricultural Research Service (In
Preparation).
45. "Evaluation of the Environmental Impact Resulting from Unconfined
Animal Production," Environmental Protection Agency (In preparation).
46. "Non-Point Water Quality Modeling in Wildland Management: A State-of-the-
Art Assessment," U.S. Forest Service, U.S. Environmental Protection
Agency, IAG No. D5-0660 (At press).
47. "Erosion and Sediment from Forest Land Uses, Management Practices, and
Disturbances in the Southeastern United States," Dissmeyer, Proceedings
of the Third Federal Inter-Agency Sedimentation Conference, 1976.
48. "Processes, Procedures, and Methods to Control Pollution Resulting
from Silvicultural Activities," U.S. Environmental Protection Agency,
Washington, D.C. EPA 430/9-73-010,(October 1973).
49. "Forest Harvest, Residue Treatment, Reforestation and Protection of
Water Quality," U.S. Environmental Protection Agency, Region X,
Seattle, Washington, EPA 910/9-76-020,(April 1976).
4-138
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50. "Silvicultural Chemicals and Protection of Water Quality," (Draft)
U.S. Environmental Protection Agency, Region X, Seattle, Washington.
51. "Logging Roads and Protection of Water Quality," U.S. Environmental
Protection Agency, Region X, Seattle, Washington, EPA 910/9-75-007,
(March 1975).
52. "Methods for Identifying and Evaluating the Nature and Extent of Non-
point Source Pollution," Environmental Protection Agency Publication
430/9-73-014 (October 1973).
53. "Processes, Procedures, and Methods to Control Pollution Resulting
from All Construction Activity," Environmental Protection Agency
Publication 430/9-73-007 (October 1973).
54. "Nonpoint Source Pollution Control Guidance, Construction Activity,"
U.S. Environmental Protection Agency, (in progress).
55. "Comparative Costs for Erosion and Sediment Control, Construction
Activities," Environmental Protection Agency Report 430/9-73-016(1973).
56. "Standard and Specifications for Soil Erosion and Sediment Control in
Developing Areas," U.S. Dept. of Agriculture, Soil Conservation Service.
57. "The Control of Pollution from Hydrographic Modifications," U.S.
Environmental Protection Agency, EPA 430/9-73-017 (1973).
58. "Impact of Hydrologic Modifications on Water Quality," U.S. Environmental
Protection Agency, EPA 600/2-75-007 (1975).
59. "EPA Nonpoint Pollution Control Guidance, Hydrologic Modifications,"
Environmental Protection Agency, Water Planning Division, (In preparation)
60. "Report on Channel Modifications," The President's Council on
Environmental Quality, United States Government Printing Office, (March
1973).
61. "Planning and Design of Open Channels," United States Department of
Agriculture, Soil Conservation Service, Technical Release No. 25
(December 1964, Revised March 1973).
62. "Water Quality Management Planning Methodology for Hydrographic Modifi-
cation Activities," Texas Water Quality Board, (December 1976).
4-139
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63. "Mathematical Simulation of the Turbidity Structure Within an Impound-
ment," U.S. Army Corps of Engineers, Research Report H-73-2.
64. "Selective Withdrawal from Man-Made. Lakes," U.S. Army Corps of
Engineers, Technical Report H-73-4.
65. "Ecological Evaluation of Proposed Discharge of Dredged or Fill
Material Into Navigable Waters," U.S. Army Corps of Engineers,
Miscellaneous Paper D-76-17.
66. "Techniques for Reducing Turbidity Associated With Present Dredging
Procedures and Operations," U.S. Army Corps of Engineers, Contract
Report D-76-4.
67. "B. Everett Jordan Lake Water Quality Study," U.S. Army Corps of
Engineers, Technical Report H-76-3.
68. "Methods for Identifying and Evaluating the Nature and Extent of Non-
point Sources of Pollutants," U.S. Environmental Protection Agency
Publication 430/9-73-014, (October 1973).
69. "Processes, Procedures and Methods to Control Pollution from Mining
Activities," U.S. Environmental Protection Agency Publication
430/9-73-011, (October 1973).
70. "Erosion and Sediment Control, Surface Mining in the Eastern U.S.,"
Volume I: Planning, Volume II: Design, EPA Technology Transfer Seminar
Publication, EPA-625/3-76-006, (October 1976).
71. "EPA Guidance for Identification and Assessment of Mining Nonpoint
Pollution Problems," (In progress).
72. Mine Drainage Abstracts, Bituminous Coal Research, Inc. i
73. "Effects of Land Disposal of Solid Wastes on Water Quality," Department
of Health, Education, and Welfare, SW-Z: Bureau of Solid Waste
Management, Cincinnati (1968).
74. "Residual Management by Land Disposal," Proceedings of the Hazardous
Waste Research Symposium, EPA Report No. 600/9-76-015 (July 1976).
4-140
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75. Solid Waste Management, D. Joseph Hagerty, Joseph L. Pavoni, and
John E. Heer, Jr., Van Nostrand Reinhold Environmental Engineering
Series, (1973).
76. "Management of Hazardous and Toxic Wastes," Paul N. Cheremisinoff,
William F. Holcomb, Pollution Engineering, 8_:4, pp. 24-32, (April 1976).
77. "Stop Leachate Problems," Michael Dilaj, John F. Lenard, Water and
Wastes Engineering, 12:10, pp. 27-40 [October 1975).
78. "The Report to Congress: Waste Disposal Practices and Their Effects on
Groundwater," Executive Summary, U.S. Environmental Protection Agency,
(April 22, 1976).
79. Solid Waste Disposal, Volume 1:Incineration and Landfill and Volume 2:
Reuse/Recycle and Pyrolysis, Baum, B. and Parker, C., Ann Arbor
Science Publishers Inc., Ann Arbor, Michigan, (Vol. 1, 1973; Vol. 2,
1974).
80. "Disposal of Sewage Sludge Into a Sanitary Landfill," U.S. Environmental
Protection Agency, Report No. SW-71d, (1974).
81. "Residual Waste Best Management Practices: A. Water Planner's Guide to
Land Disposal," U.S. Environmental Protection Agency, EPA-440/9-76-022
(in progress).
4-141
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CHAPTER 5
ANALYSIS OF STREAM IMPACTS FOR URBAN AND NONURBAN SOURCES
5.1 Introduction
The preliminary assessment methodology presented in Chapter 2 provides
analysis techniques which can be used to identify existing and potential
water quality problem areas. The methods are set in a rather broad
planning context which sacrifices details within the study area in favor
of regional load assessment and problem area identification. In effect,
Chapter 2 provides the 208 planner with planning tools which permit him
to reduce the dimensionality of his problem, that is limit the number of
river miles and water quality variables which should be subjected to
more definitive analysis.
Chapter 5 presents methodologies for more detailed assessments of existing
and potential problem areas identified in the preliminary problem
assessment phase of the 208 program. In this regard, Chapter 5 includes
another level of detail for assessing water quality in streams. Simplified
modeling methods are described for determining receiving water quality
responses to continuous and intermittent loads described in Chapters 3
and 4. The time and space scales of the modeling framework are reduced
from those in Chapter 2. Spatial resolution in the analysis described
in Chapter 5 ranges from local to sub-basin scale. The time scale
permits an evaluation of water quality response characteristics over the
course of a few weeks. This is in contrast to the steady state average
annual water quality responses generated in Chapter 2. The principal
water quality variables considered in these time and space scales are
BOD, dissolved oxygen, suspended solids, total nutrients and coliform
organisms. The principal emphasis in the chapter is on urban loads.
5-1
-------
Special techniques are described for simplifying the structure of the
water quality analysis in streams. These include guidelines for
aggregating loads or for treating local distributed loads as point
sources and simple methods for incorporating dispersion estimates into
the stream analysis. Finally the chapter presents an example stream
analysis which draws on load generation techniques and modeling methods
presented in Chapters 2, 3 and 4. The example proceeds from the
development of the variable loads through model application. Special
sub-sections of the chapter cover model calibration and methods for
developing time dependent results from steady state water quality models.
Lakes, estuaries and coastal areas are also considered in Chapter 5.
The level of detail employed in these analyses is less sophisticated
than that for streams, and is similar in scope to the preliminary
assessment techniques employed in Chapter 2. The reason is that lakes,
estuaries and coastal areas are characterized by complex transport
mechanisms, the analysis of which is not easily structured in the
simplified form which characterizes advective transport in streams.
Furthermore, the nature of water quality problems in these systems
frequently requires multi-dimensional analyses or solutions involving
complex reactions and interactions between variables, and are beyond the
scope of the present manual.
Chapter 5 does, however, present methods for identifying and analysing
existing and potential water quality problem areas in complex water
bodies. In certain cases, these methods will be satisfactory by
themselves. In others, the analysis will point to problems which can
only ,be satisfactorily resolved with numerical modeling techniques.
Criteria for making these distinctions are presented in this chapter.
Finally, Chapter 5 presents guidelines for using numerical computer
models to analyse specific problems which are not amenable to analysis
techniques described in this manual.
Chapter 5 presents a simplified procedure for analysing a set of complex
and very sophisticated water quality problems, those associated with
stormwater. The analysis includes methodologies for assessing storm
5-2
-------
water impacts in streams which can be performed with an electronic
calculator or with relatively simple computer programs which are readily
available. The purpose of this analysis is to reduce the complexity of
the water quality modeling effort to the point where reliable assessments
of storm water impacts and their controls can be made with a minimum
expenditure of resources.
The methods in this manual are not viewed as a replacement for more
sophisticated storm water modeling frameworks. Instead, they are designed
to be part of the 208 planner's library of analysis tools. Until this
time, there has been no reliable storm water evaluation methodology
which could be used to determine storm water control requirements in the
time frame of a few weeks. Most storm water programs require at least
that time to develop the data input for the model. The present method
is designed to satisfy the need for a reliable yet inexpensive evaluation
of storm related problems.
The method employs steady state water quality models of stream systems.
In this regard, the fundamental tools are classical and familiar to most
208 planners. The method, however, yields results which contain a great
deal of time variable information. Consider a stream which is subjected
to pulse loadings from storm events. The water quality response can be
viewed as a series of pulse storm water responses which spread as they
move downstream. The steady state model must be interpreted in a very
specialized way in this case. First, the response represents the worst
water quality condition at each point downstream, as the pulse travels
downstream. Secondly, the model results are attenuated in the downstream
direction, reflecting the natural attenuation of the peak response due
to longitudinal dispersion. Other refinements and modifications to the
steady state model are also included in this chapter. Each of these are
included to maximize the time variable information content developed
from the model.
5.2 Stream Water Quality Analysis Methods (Non-Steady State)
Steady state stream analysis has been generally considered to be of limited
usefulness in evaluating the water quality response due to non-steady
5-3
-------
state loads. The problem centers on the inability of the steady state
model to represent transient water quality responses due to short term
load variations. However, because of the ease with which steady state
water quality models can be developed and applied, they are frequently
used to make estimates of extreme conditions which might result from a
time variable load. For example, it is a common practice to use short
term loading extremes to estimate extreme water quality occurrences. An
analysis of this type is presented in Section 2.7.1.2 (pg. 2-101) where
a steady,state model is employed to evaluate dissolved oxygen response
in the hypothetical South River under an extreme storm event (extreme
high flow, extreme wet weather load). The analysis is reasonable, since
the duration of the loading event is sufficiently long to approach
steady state in the River.
Recent developments, however, have extended the capabilities of simplified
analyses in assessing transient water quality responses. Analysis techniques
presented in this chapter consider the time variable response to continuous
and intermittent loads using modified steady state models. The methods are
consistent with others in this manual in that the analysis techniques can
be performed without the assistance of computerized numerical models'.
Before considering these methods, a brief discussion of model verification
and calibration is presented at this point because it is clear that an
adequate representation of water quality responses can be developed only
if the adequacy of the model can be demonstrated by a comparison against
field data. These models can be computerized numerical models or, as is
used in this chapter, the equations in Table 2-17 (pg. 2-83).
5.2.1 Criteria for Model Verification
Water quality projections have an associated level of reliability which
is related to the models ability to reproduce observed receiving water
responses in the particular study area being considered. That is, if a
model has been developed, its reliability in making forecasts is assessed
by its ability to compute water quality similar to that measured in
field data collection programs. The methods by which reliability is
developed is called model verification analysis.
5-4
-------
There are a number of levels of model verification which can be pursued
ranging from gross comparisons of computed water quality with a single
set of grab samples to a comprehensive verification, which utilizes data
sets collected at many combinations of river flow, seasonal factors
(temperature, rainfall, etc.) and loading.
The degree to which any model should be verified is normally decided on
the basis of:
1. The degree of confidence which must be maintained in the model
proj ections.
2. The potential range of costs which could result from management
decisions that the model outputs will impact.
3. The range of flow, temperature, and loading conditions which
the model will be used to evaluate.
4. Resources available for model development and testing.
Generally the last item, cost, is an overriding concern since model
verification is costly and time consuming. As the model application
proceeds in a continuing planning process, factors 1 through 3 may dictate
additional model verification work to develop more detailed input to the
planning process.
Calibration is a term applied to verification analyses which are limited.
Normally full model verifications require model comparisons with three
to four complete sets of observed data, while calibrations normally rely
on a reduced data base with fewer, or less complete data sets.
Since stream models applying methods contained in this chapter are to be
used in generating step 1 planning guidance, some model calibration is
justified and encouraged. The level of verification required must be
decided on a site specific basis using the four criteria cited above as
guidelines. In most cases because of a lack of extensive historical
data, model calibration against 1 or 2 sets of available data will be a
practical upper limit.
5-5
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5.2.1.1 Model Calibration Analysis
Model calibration consists of four tasks: Data preparation and analysis,
preparation of model input, model application and comparison of model
results with measured water quality data.
Chapter 2 describes possible sources of historic water quality data and
presents some examples of data presentation methods which are appropriate
in a model calibration exercise. For example see Figures 2-2 (pg. 2-
12), 2-3 (pg. 2-13), and 2-13 (pg. 2-47). Normally, companion data are
available to establish the appropriate river flows, Table 2-3(a) (pg. 2-
23), and seasonal temperature, Figure 2-12(b) (pg. 2-35). Chapter 2
provides some guidance in the preparation of loading data. Efforts
should be made wherever possible to gather loading data from measurements
collected during the receiving water quality surveys. Where data
collection is required to develop a data base for model verification,
the Monitoring and Surveillance Appendix to this manual provides guidance
in developing adequate programs.
The data is then assembled in a manner consistent with the input
requirements to the model. Finally, the model results are compared to
measured data and an evaluation is made as to whether the model adequately
reproduces the observations. If not, the model input data (temperature,
flow, load measurements, depths, etc.) should be refined or modifications
made in the model coefficients.
When the calibration is judged to be acceptable, the following criteria
should be satisfied:"
1. Model loads and river flows should be those which were measured.
2. Model coefficients should be within acceptable limits described
in Chapter 2.
3. Model coefficients should be internally consistent and should
not vary indiscriminately from segment to segment.
4. The computed water quality should at least reproduce major
trends in the observations. It is not necessary for the
computed water quality profile to go through every data point.
5-6
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An example of. an acceptable calibration using the South River data is
demonstrated in Figure 5-1. The calibration analysis indicates that the
South River model is only in marginal agreement with the observed suspended
solids concentrations. Additional effort should be directed toward
refining the model loads which were poorly defined in the existing data
base. Calibration of other water quality variables appears to be adequate.
A second calibration analysis would enhance the reliability of the model
considerably.
Section 5.2.1.1 has reviewed the basic elements of model calibration in
general terms, allowing a certain amount of latitude because of the
Phase 1 planning function of models developed in this chapter and the
site specific nature' of water quality problems and verification
requirements. A more definitive description of model calibration and
verification procedures can be found in references (1, 2) and in the
model applicability Appendix.
5.2.2 Time Variable Load Characteristics
5.2.2.1 Continuous Loads
Time variable loads are broadly categorized as continuous and intermittent.
Continuous loads are those which are always or nearly always discharging
within the time scale of the analysis. The magnitude of the loading,
however, can be variable in time. For most applications the non-steady
state characteristics of continuous discharges can be ignored because
the load variability is small relative to the mean loading, at least
within the time scale of the problem. For example, most municipal and
industrial discharges have relatively constant dry weather mass loads.
This is shown schematically in Figure 5-2(a).
Other municipal loads may exhibit large load variations reflecting the
inflow characteristics of combined sewer systems. In such cases, the
load might be treated as constant only during dry weather periods, and
the loading dynamics might have to be incorporated into the receiving
water analysis during wet weather simulations. The degree to which this
distinction has to be made is dependent upon the magnitude of the load
5-7
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U)
e>
X
o —
O v.
Ss
o -'
co
CO
O
CO
cn
E
LEAVER RIVER
BROWN RSR CO.
15
10
5
600
400
200
Kr=.IO/DAY
CO
S S
ce o
o o
10,000
1,000
100
IO
STP*2 AND STP*i AMERICAN
STORM SEWER CSO I PAPER CO.
I mil I
DRY WEATHER PERIOD
TEMPERATURE =2S°C
BASE FLOW = 93CFS
©— OBSERVED
— COMPUTED
IO
15 2O
(b)
25
30
35
SATURATION^ S.l/mg/l
10
15 20
(C)
25
O O
\
I
10
15 20
(d)
25
I
I
_L
I
10 15 20 25
MILES BELOW ROUTE 80
SOUTH RIVER
30
30
30
35
35
35
FIGURE 5-1
HYPOTHETICAL SOUTH RIVER-MODEL CALIBRATION ANALYSIS
5-8
-------
10
'o
OT
O
o
a.
CONTINUOUS LOAD
ex: TREATMENT PLANT
(o)
-9O % CONFIDENCE BANDS
JH^S*^~-I
5678
TIME-DAYS
10 II
12 13
14
10
O
I
>..
OT
O
H
O
a.
678
TIME-DAYS
50
to
'o 40
X
r* so
20
CO
o
5 10
(c)
INTERMITTENT LOAD
ex: STORM SEWER
5678
TIME-DAYS
II 12 13 14
FIGURE 5-2
EXAMPLES OF LOAD TYPES
5-9
-------
variability and must be evaluated on a case by case basis. In general
the hydraulic capacity of the plant and the combined sewer system puts
an upper limit on the load variability.
5.2.2.2 Intermittent Loads
The second category of time variable loads, the intermittent load, is
characterized by an on-off type of behavior. Typical of this type of
load is the loading from a storm water outlet. During dry periods, the
discharge is zero, and during and immediately after the storm, a major
pulse load occurs. Figure 5-2(c) typifies this behavior. Normally
intermittent loads cannot be effectively treated as steady state. The
loading is simply not sustained for a period of time which approaches
the time-to-steady state in the receiving water. A number of water
quality analysis techniques exist for evaluating receiving water responses
to this type of pulse load. Most of these involve detailed time variable
integrations of receiving water equations with detailed loading histories
as inputs.
5.2.2.3 General Classification of Loads
Between the continuous and the intermittent loads is a spectrum of the
time variable loadings which possess characteristics of both types.
Typical of these loads are loadings from wastewater treatment facilities
servicing combined sewer systems and industrial loads having high
volumes of batch production. It is important for the engineer to analyse
the load mix to a receiving water and segregate the various loads into
steady state and time variable categories. Each loading type is treated
differently in the water quality simulation analysis.
5.2.3 Stream Response Characteristics
The water quality response in streams varies depending upon the nature
of the loading function. Stream response to continuous point and
distributed sources is discussed in Chapter 2. Steady state responses
to conservative, reactive and coupled system variables is given in that
chapter. Time variable loads from continuous discharges and other
5-10
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intermittent loadings result in similar water quality responses. However,
in this case, the response has an associated variability which is largely
dependent upon the variability of the loading function.
In order to understand the relationship between load variability and
water quality variations one can view the stream as a purely advective
system, that is a plug flow system. If such a system is loaded with a
series of pulse loads of a conservative tracer as indicated in Figure 5-3(a),
measurements at a downstream point would yield a series of pulse responses
as indicated in Figure 5-3(b). The time between the measured pulses and
their magnitude would be directly related to the characteristics of the
input loading function and the pertinent stream characteristics such as
river flow, channel characteristics, etc.
In natural water systems, there is normally some longitudinal mixing
taking place as the pulses move downstream. The effect of such mixing,
or dispersion as it is commonly called, is to spread the pulses out as
indicated in Figure 5-3(c). Dispersion in stream systems can be neglected
where the time of travel is short. However, in other situations it is a
factor in attenuating the response to discrete pulse loading events.
Analysis of the dispersion problem can be accomplished using the curve
displayed in Figure 5-4. The Figure displays percent attenuation of the
\
peak concentration as a function of travel time in the stream and the
duration of the rainfall event. Steady state model responses can be
adjusted accordingly to account for dispersion effects. A complete
discussion of the theoretical basis for Figure 5-4 is contained in
Reference 3. Computer programs discussed in Appendix A can also be used
to evaluate the problem further. In any event, methods presented in
this manual will yield conservative water quality responses downstream
of the point at which dispersion becomes a relevant factor. Dispersion
in stream systems is included in the present analysis.
Chapter 3 described the statistical characteristics of intermittent load
histories such as that displayed in Figure 5-3. The underlying density
function was shown to be gamma distributed, having a mean, W , and a
coefficient of variation, v . The coefficient of variation is defined
' w
5-11
-------
THOUSAND POUNDS/DAY
— ro w t>
_o o o o o
(a)
PULSE
)
LOAD
A
, 1 ,'
2 3
1
C
1
D
4567
TIME-DAYS
(b)
CONCENTRATION (mg/l)
O — tv> Ol * O
ADVECTIVE STREAM
<&T
= 7 DAYS
(NO DISPERSION)
U=2 MILES /DAY
-
D
1
1 1
C
|
I i
B
1 I
1 i
A
1
56789
DISTANCE-MILES
10 II 12 13 14
ADVECTIVE STREAM
(DISPERSION)
U=2 MILES/DAY
56789
DISTANCE-MILES
FIGURE 5-3
STREAM RESPONSE CHARACTERISTICS TO PULSE LOADS
5-12
-------
1.0
OS
^ 0.8
0.6
0.5
0.4
0.3
0.2
0.1
NOTE:
E • DISPERSION COEFFICIENT (m!2/DAY)
U « STREAM VELOCITY (ml/DAY)
i * DURATION OF STORM (DAYS)
t • TIME SINCE BEGININQ OF STORM (DAYS)
X « U (t-d/2)
' DISTANCE DOWNSTREAM FROM STORM LOAD (ml)
I I I I I I I
I
I I I I I I
O05
ai
0.2
0.5
1.0
DIMENSIONLESS FACTOR =
2JO
2Et
so
10.0
FIGURE 5-4
EFFECT OF DISPERSION ON POLLUTANT
CONCENTRATION AT MIDPOINT OF STORM PULSE
5-13
-------
as the standard deviation divided by the mean. The subscript w denotes
that this is a statistic of the load W(t).
The analysis methods for evaluating in-stream water quality responses
due to intermittent loads utilizes the statistics of receiving water
quality due to that load. The behavior of the system can be thought of
as analogous to the pulse load example presented in Figure 5-3, the
difference being that instead of inputting a time history of discrete
load events, the statistics of the history of those events is input to
the stream model. The model then generates a statistical water quality
response consisting of a mean and a standard deviation at all points
downstream of the load. The frequency distribution of the water quality
response is identical to that of the input load for the case of a single
load or a closely grouped set of similar loads. For cases where there
are numerous loads, all having different undefined density functions,
the Central Limit Theorem suggests that the downstream water quality
frequency distribution approaches a normal distribution. However, in
cases where the spatial extent of the study area is small, and dominated
by storm related loadings the underlying water quality frequency
distribution is best described by that for the loads (i.e., a gamma
distribution).(4)
The concept is shown diagramatically in Figure 5-5. Here two loads are
shown: a continous steady state load and an intermittent load. The
statistics of the loads can be generated using the methods presented in
Chapter 3. The continuous load is characterized completely by its mean,
W, (Chapter 2), the intermittent load is characterized completely by its
mean, W,, its coefficient of variation, v , and its distribution function.
The stream model shown in the Figure is the subject of discussion in the
next section. It consists of the stream characteristics described in
Chapter 2: channel geometry, reaction rates, and transport (
characteristics. Its function is to translate the load statistics from
various sources into a water quality response having a computed mean and
standard deviation. An alternate method for achieving similar results
using empirical relationships is demonstrated in Section 5.3.4.
5-14
-------
I
co
m
90% LOAD
MEAN
LOAD
(O
CD
Q
g
TIME
CWRT/W,GAMMA DISTRIBUTED]
10% LOAD
50% LOAD
90% LOAD
DISTANCE
z
UJ
§
o
LJ
o
CO
CO
90% LOAD
DISTANCE
FIGURE 5-5
WATER QUALITY RESPONSE SIMULATOR
BOD-DISSOLVED OXYGEN EXAMPLE
5-15
-------
5.2.3.1 Time Variable Water Quality Simulator
In Chapter 2 a summary of equations for computing pollutant concentrations
in receiving waters are presented (Table 2-17, pg. 2-83). The reader is
referred to Section 2.6.3.1 through 2.6.3.4 (pg. 2-82 to 2-97) for a
detailed discussion of the coefficients in these equations.
In the special case of constant flow advective systems, the variability
characteristics of the response function as a function of load variability
are well known. In particular, it can be demonstrated that the coefficient
of variation of the water quality response at any location is equal to
the coefficient of variation of the input loads(5). That is:
oc ow /-r i -,
v = — - v = — (5-1)
c — w — ^ J
c w
where: v . v are the coefficients of variation of concentration and load
c w
a , a are the standard deviation of concentration and load
c w
c, w are the mean concentration and mean load.
Thus knowing the mean load and its variability one can compute the mean
response using a steady state water quality model and then calculate the
variability of the water quality response using the above relationships.
This is a valid and recommended approach to analysing variable load
impacts on streams where the constant flow assumption holds.
For example if one knows that a single point source has a mean load of
3 2
10 Ib/day, a standard deviation of 10 lb/day, and a normal probability
density function, it is a trivial problem to determine the mean load
response and superimpose on that response a normal probability distribution
having a coefficient of variation of 0.10. The 68% variability around
the mean response in this case would be: v • c, or 0.1 • c. This
formulation only applies to constant flow systems.
However, in situations where intermittent loads such as storm related
loads exist the impact of the load on the advective flow is often a
major factor. Thus:
5-16
-------
vc vw
and other approaches must be developed. One such approach is presented
in the example problem of Chapter 5. An alternative approach is presented
in Reference (6).
As in Chapter 2, the unit response in water quality due to a single load
to a linear system can be computed independently of all other loads.
This is also true in the time variable simulator. However, a different
set of ground rules must be established for combining the water quality
responses due to a number of intermittent loads.
One base premise can be established: the water quality responses due to
mean loads calculated from equations presented in Table 2-17 (pg. 2-83)
are additive. That is the total mean water quality response is the sum
of responses due to mean loads at all discharge points. However, the
frequency distribution of the response function is normally not known
even if the load frequency distributions are defined. Thus questions
regarding expectations of water quality responses having specified
levels are difficult to answer given the mean loads and their probability
density functions.
The approach taken in this manual is one where the load statistics are
developed in sufficient detail to permit statements regarding the
expectation of various loads. The storm related loads are then interpreted
in terms of the frequency with which they are expected to occur during
wet weather (due to storms) and during longer term periods which include
storms (i,.e., season, year). The storm loads of given frequency and
their associated flow are then used to compute water quality responses
which will occur with approximately the same frequency as those loads.
For example, if one determines that the 60% storm event (that which will
be exceeded by only 40% of the storms) is a loading event which will only
be exceeded 2% of the time, the water quality response due to that load is
expected to occur with roughly the same frequency, 2% of the time. Within
this analysis framework the storm related loads are expected to be
correlated to a relatively high degree. That is, large storms cause
correspondingly large loads at all wet weather discharges in an urban
area.
5-17
-------
The pollutant concentrations developed using this method will generally
be within the accuracy of the level of stream analysis presented in this
chapter. Methods for combining unit responses, discussed in Section
2.6.3.1, are appropriate within the context of Chapter 5.
5.2.3.2 Aggregating Loads for Representation as Point
Sources
In some cases where a number of similar loads are located close to each
other relative to the spatial scale of the water quality problem being
modeled, it is possible, and in most cases desirable, to aggregate loads
into a single point source. This treatment of loads simplifies the
analysis with little effect on the accuracy of the calculated receiving
water quality.
In general loads can be aggregated with ho more than a 5% error in
accuracy if they lie within a distance described by:
x < 0.05 §• (5-2)
— K
where: U = river velocity (miles/day)
K = first order reaction rate (per day)
For example, consider the carbonaceous BOD load distribution shown in
Figure 5-6(a). If the river flow is estimated to be 10 miles/day and
the first order BOD reaction rate is taken as 0.2 per day, the distance
over which loads can be aggregated is 2.5 miles:
x < 0.05 - < 2.5 miles
— u . ^
The resulting aggregated point source loads are shown in Figure 5-6 (b).
The basis for equation (5-2) is a simple computation which evaluates the
equation for a first order reactive substance (Table 2-17 pg. 2-83) at
the point where the discharge occurs and at a downstream point where the
concentration has been reduced by 5%. Equation (5-2) results when the
equations at the two points are subtracted.
5-18
-------
(0)
STORM SEWER SYSTEM
ie
(b)
AGGREGATION
INCLUDES A,B8C
U » IO UILES/OAY
Kr« 0.2 /DAY
= 0.05 —=2.5 MILES
FIGURE 5-6
METHOD FOR AGGREGATING LOADS IN STREAMS
5-19
-------
5.2.4 Application of Stream Impact Analysis Methods
Analysis methods presented thus far are illustrated in this section.
The principal emphasis will be to apply the load generation techniques
from Chapter 3 and the stream impact analysis methods discussed thus far
in Chapter 5 in a typical 208 planning area setting. The hypothetical
Jefferson City study area which was analysed in a preliminary manner in
Chapter 2 is used for this purpose.
Analysis methods demonstrated here are more detailed than those from
Chapter 2. Some of the simplifying assumptions regarding urban land
use, sewerage systems and river characteristics are replaced with detailed
representations more consistent with study area characteristics which
the 208 planner is likely to encounter. In addition, a set of realistic,
but hypothetical, problem constraints are imposed to demonstrate a
broader scope of planning problems and opportunities. While the example
analysis is designed to be instructional in nature, it is site specific
to the Jefferson City study area. Therefore the 208 planner should use
the methodology behind the example as a pattern for structuring a water
quality impact analysis in his specific study area. He should not
simply attempt to reproduce the computations presented in this section
in another study area.
As indicated above, the problem setting is basically "the same as the
Jefferson City-South River problem setting from Chapter 2. The following
modifications are instituted, however, to make the study area more
realistic:
1. The urban area is described in terms of its major land use
classifications.
2. A second treatment plant is included at an upstream location.
3. The major features of the sewer systems are described.
4. A water treatment plant is located above the city.
5. A realistic set of population projections are developed.
These details are presented in Section 5.2.4.1.
5-20
-------
5.2.4.1 Problem Setting
The hypothetical Jefferson City is located on the South River (Figure 2-
5 pg. 2-18). The urban area consists of two sewer districts designated
Sewer District No. 1 and Sewer District No. 2. These are shown in
Figure 5-7. District No. 1 located on the north side of the River has a
20 year old combined sewer system which services an area of 8,000 acres.
A primary wastewater treatment plant having an average daily design
capacity of 9 MGD services the area. The plant is presently operated at
its full design capacity. Present plans are to convert this plant to a
secondary treatment facility within the planning period. Both the
combined sewer system and the plant have a peak hydraulic capacity of 36
MGD. Combined sewer overflow regulators bypass excess flows to the
South River at three locations indicated in the figure.
Projected land use types within sewer District No. 1 at the end of a 20
year planning period are shown in Figure 5-8. The area is an established
urban area having a central commercial district surrounded by light
industry and residential housing. Industrial wastewaters are presently
collected at a central location and pumped untreated to the primary
treatment plant through a force main.
Sewer District No. 2 was constructed 10 years ago to service the rapidly
growing area to the west and south of the central City. Development
style housing and a new commercial district contribute to low to moderate
population density within this area at present. Planning projections
for the area indicate a trend toward more dense residential housing in
the future. Figure 5-8 shows the projected land use patterns. A separate
sanitary sewer system services the district and conveys treated wastewaters
to a secondary treatment plant at the west end of the City. A force
main conveys sanitary wastewaters from the south side of the South River
to the plant which has an average daily design capacity of 12 MGD. The
plant presently treats 11 MGD. A storm sewer system services District
No. 2. Its design capacity is in excess of 900 MGD. Overflows operated
by weir type regulators are activated by excess flows.
5-21
-------
-r
LEGEND:
03 PUMP STATIONS
HI COMBINED SEWER OVERFLOW REGULATORS
(U STORM SEWER OVERFLOW REGULATORS
tWTPl WATER TREATMENT PLANT
IWWTPI WASTE WATER TREATMENT PLANT
—— SANITARY SEWERS
.._—.. COMBINED SEWERS
STORM SEWERS
•—FORCE MAINS
I
SCALE
1/2
HILES
FIGURE 5-7
JEFFERSON CITY STUDY AREA
COLLECTION SYSTEM
5-22
-------
LOW DENSITY RESIDENTIAL
1^"
.LOW DENSITY
/
. .'. RESIDENTIAL .
DOOOOOOOOOOOOOOOO
3OOOOOOOOOOOOOOOO
oooooooa
^oooopoooqoo
AGRICULTURAL AND LOW DENSITY RESIDENTIAL
1/2
MILES
FIGURE 5-8
JEFFERSON CITY STUDY AREA
LAND USE CLASSIFICATION
5-23
-------
A water treatment plant having a design life of 30 years was just
constructed in a rural area west of town to service Jefferson City. The
entire water supply for the City is withdrawn from the South River at
this point.
Continued growth is expected throughout the urban-suburban area. Recent
population studies conducted as part of the water supply plan are displayed
in Figure 5-9. The population figures have been reworked along sewer
district boundaries. In general, District No. 1 is expected to have
only moderate growth during the next 25 years, while District No. 2 is
expected to increase in population by between 35 and 110 percent.
5.2.4.2 Load Estimation
Load estimates for the Jefferson City study area are generated in a
preliminary fashion in Chapter 2. The reader is referred to that chapter
and the load generation techniques in Chapter 3 for specific details
which are not repeated here. Non-urban loads from upstream and surrounding
forest and rural areas are derived from Chapter 2.
The rainfall characteristics in the hypothetical South River Basin are
taken as those for U.S. Weather Bureau Station 052220 displayed in
Figure 3-15 (pg. 3-60). Two periods are considered in this chapter:
the average summer storm condition (June through September), and the
period of peak storm intensity, July. The rainfall characteristics
during these two periods are displayed in Table 5-1.
5-24
-------
350
300
CO 250
Q
CO
O
I
h-
0
200
ISO
100
50
40
POPULATION PROJECTIONS
HYPOTHETICAL JEFFERSON CITY
TOTAL FOR JEFFERSON C.TY
30
20
10
10
PLANNING
PRESENT.
TIME
20
^
FIGURE 5-9
POPULATION PROJECTION
JEFFERSON CITY
5-25
-------
TABLE 5-1
RAINFALL CHARACTERISTICS
HYPOTHETICAL SOUTH RIVER STUDY AREA
(a) SUMMER STORM PERIOD - JUNE THROUGH SEPTEMBER
Characteristic
Mean
Storm Intensity
Duration
Volume
Time Between Storms
Characteristics
Storm Intensity
Duration
Volume
Time Between Storms
I = 0.055 in/hr
D = 3.0 Hrs.
V = 0.18 in
A = 80 Hrs.
(b) JULY STORM PERIOD
Mean
I = 0.062 in/hr.
D = 2.5 Hrs.
V = 0.17 in
A = 70 Hrs.
Variation
v. = 1.55
vd = 1'15
\ = 1-90
v= i-15
Variation
v± = 1.50
v, = 1.00
d
v =1.20
v
v, = 1.20
Projected land use classifications within the two sewer districts for
the 20 year planning period are displayed in Table 5-2. The information
in this table was developed by the 208 study program and indicates
anticipated land use classifications 20 years in the future. The total
land area in District No. 2 is twice that for District No. 1. Both
districts are expected to be dominated by medium density housing.
5-26
-------
TABLE 5-2
/
LAND USE CLASSIFICATION IN THE HYPOTHETICAL JEFFERSON CITY
(Based on Population and Land Use Projections)
S. D. No. 1 S. D. No. 2 Total
Classification
Low Dens. Hous.
Med Dens. Hous.
High Dens. Hous.
Commercial
Institutional
Light Industry
Totals
Area
(Acres)
2,120
2,800
1,600
540
120
800
7,980
%
26.6
35.1
20.0
6.8
1.5
10.0
100.0
Area
(Acres)
2,640
8,800
2,640
940
-
-
15,020
%
17.6
58.6
17.6
6.2
-
_
100.0
Area
(Acres)
4,760
11,600
4,240
1,480
120
800
23,000
%
20.7
50.5
18.4
6.4
0.5
3.5
100.0
Using the methods described on page 3-30 the percent imperviousness of
the urban area within the two sewer districts is computed to be:
Sewer District No. 1 - 40.9% impervious
Sewer District No. 2 - 42.5% impervious
The runoff coefficients for the two Districts developed from Figure 3-8
are:
Sewer District No. 1, C = .45
Sewer District No. 2, C = .47
These are in agreement with the value of 0.42 developed in the preliminary
assessment (pg. 2-59 and Figure 2-15).
Runoff from the study area for the storm periods described in Table 5-1
are computed using methods from Section 3.4.3.2. A sample analysis of
this type is presented on pages 3-59 and 3-60. The anticipated probability
distribution of runoff flows 20 years in the future are presented in
Table 5-3.
5-27
-------
TABLE 5-3
RUNOFF FLOW, Q_ = C.JA
K V
(IN CUBIC FEET PER SECOND)
20 YEARS IN FUTURE
% of
Storms
Less
Than
20
50 (ME AN)
75
90
95
Multiple
of the
mean
Factor
( -10)
(0.4)
(1.4)
(2.7)
(3.9)
S. D.
Summer
Storms
20
79(198)
277
535
772
No. 1
July
Storms
23
93(233)
326
602
870
S. D. No
Summer
Storms
39
155(388)
543
1048
1513
. 2
July
Storms
44
175(437)
611
1180
1704
where: vq = v- = 1.55 for the average summer storm condition;
v- = 1.50 for the peak intensity storm period, July;
The factor is the multiple of the mean from Figure
3-llb for v = 1.55.
( ) = The mean runoff flow in cfs calculated using
Equation 3-15.
The product of the factor and the mean flow yields the runoff flow
having the indicated probability. For example the 75% runoff from Sewer
District No. 1 in July is 1.4 (233) = 326 cfs.
The loads associated with these flows can now be computed using methods
presented in 3.4.3.3 and demonstrated on pages 3-60 through 3-62. In
general pollutant concentration is assumed to be independent of flow, an
adequate assumption in the absence of site specific data. That is, the
mean concentration during storm events is only weakly correlated to the
mean flow during that event. However, best engineering practice is to
obtain measurements of pollutant concentrations at various storm water
flow conditions and verify concentration-flow independence on a site
specific basis. In cases where significant long term correlations do
exist, an appropriate adjustment to the analysis procedure would have
to be made.
5-28
-------
The basic data for computing the storm loads for the hypothetical Jefferson
City urban area are contained in Table 3-3. Without a correlation for the
specific site between the concentration and total runoff flow, the variability
of the flow and concentration cannot both be used as in equation 3-20 to
determine the variability of the load. The correlation between concentration
and runoff flow is not known on the South River. The coefficient of varia-
tion for the loads from the two storm conditions are, therefore, taken as
the coefficients of variation of the runoff flow. That is, it is assumed
that concentration is essentially constant from event to event and:
Average summer storm condition; v =1.55
July storm condition; v =1.50
7 w
The assumption of constant concentration appears to be an acceptable
simplification based on data collected in numerous U.S. cities. However,
an alternative procedure which includes observed variability in
concentration is presented on page 3-62 and can be applied where the
flow-concentration relationships are available from an observed
data base. The loads from intermittent sources in the South River study
area are displayed in Table 5-4.
Point source loads from the two municipal wastewater treatment plants in
Jefferson City are expected to increase during the planning period. The
loadings are developed from the "reasonable" set of population projections
assuming the same treatment as presently exists at expanded treatment
facilities in Sewer District No. 2, and upgrading of the Sewer District
No. 1 plant to at least secondary treatment. The loadings from both
plants are estimated in Tab'le 5-5. For example, in Sewer District No.
1, the total nitrogen load using the reasonable population projections
(Figure 5-9) is computed as: w = 20 mg/1 x 10~ x 8.34 x 1.12 x 10 people
x 150 gpc/day = 2818 Ibs/day. Tributary and industrial loads are those
presented in Chapter 2.
5-29
-------
on
I
W
o
TABLE 5-4
SUMMARY OF STORM RELATED LOADS TO THE HYPOTHETICAL SOUTH RIVER
(1) BOD5 Loads W - (Thousand Pounds/Day) ^ TMal Coli£or]n Loa
-------
TABLE 5-5
MUNICIPAL TREATMENT PLANT LOADS - 20 YEARS IN FUTURE
HYPOTHETICAL JEFFERSON CITY
Total Nitrogen Total Phosphorus Total S.S.
Discharge
S.D. #1 plant
S.D. #2 plant
Discharge
S.D. #1 plant
S.D. #2 plant
Flow
16.9
30.4
Flow
16.9
30.4
rag/1
20
20
B(
rag/1
30
30
lbs/da)
2818
5070
DD5
Ib/day
4228
7606
r mg/1
10
10
Total
No./ 100
1000
1000
Ibs/day rag/1
1409 19.8
2535 19.8
Co li forms
ml No. /day
6.4X1011
l.lxlO12
Ibs/day
2791
5020
5.2.4.3 Stream Impact Analysis Conditions
The first step in the stream impact analysis is to reverify the conclusions
resulting from the preliminary assessment procedures presented in Chapter
2. Those conclusions are summarized in Table 2-26. It is possible that
the reestimation of loadings could significantly change one or more of
these conclusions.
This task is accomplished by simply repeating the analysis for present and
projected loading conditions and verifying that the water quality responses
resulting from the more refined loads and the statistical water quality
analysis methods of Chapter 5 lead to the same conclusions regarding the
probability of potential problems. This of course, assumes that the basic
water quality model has been adequately calibrated to the specific site at
least for steady state conditions as discussed in Section 5.2.1.
Bottom demands are not included in the South River example. It should
be pointed out that many problem cases will have significant dissolved
oxygen water quality impacts because of bottom demands. In these cases
the analysis framework can be extended to include bottom effects by
including bottom demand terms in the equations displayed in Tables 2-17
as discussed in Section 5.5 and illustrated in Table 5-21.
5-31
-------
The procedure for applying the time variable water quality method using
the statistical loads is illustrated in this section. Because of space
limitations a complete set of analyses for the South River will not be
developed. Rather, a selected group of problem cases will be analyzed
to demonstrate techniques in applying the statistical water quality
method and interpreting its outputs. Toward this end, the method application
to reverify the conclusions generated in Chapter 2 is omitted and the
analysis focuses on the specific problem cases outlined in Table 5-6.
TABLE 5-6
CRITICAL WATER QUALITY CONDITIONS
HYPOTHETICAL SOUTH RIVER
Water Quality Indicator
Dissolved Sanitary Eutrophi- Suspended
River Flow Condition Oxygen W.Q. cation Solids
Drought flow X
Average summer flow X
Peak summer storm flows XX X
Table 5-6 indicates flow conditions for which specific water quality
problems-will be analyzed. Dissolved oxygen concentrations in the
Chapter 2 analysis were shown to be critical during drought flow conditions
and during peak storm runoff conditions. The point sources dominated
the drought flow response while combined sewer overflows were a principal
contributor to the low dissolved oxygen during storm periods. Sanitary
water quality problems were maximum during peak storm conditions. The
combined sewer overflows contributed a major portion of the loading in
this case. The preliminary eutrophication analysis indicated probable
water quality problems during long term average loading conditions
indicative of the average summer flow condition. The possible suspended
solids problem case is reanalysed in this chapter during wet weather
periods when urban non-point sources are significant.
The reader should note that the South River study area has been modified
somewhat in Chapter 5 to make the example more illustrative. Therefore,
water quality responses in the River are expected to be different than
5-32
-------
those presented in Chapter 2. In addition, the analyses presented here
represent conditions 20 years in the future. Therefore, land use types,
loadings and river flows developed for future conditions (Sections
5.2.4.1 and 5.2.4.2) are applied in the analysis. Subsequent analysis
in Chapter 6 will deal with load allocation techniques, control practices
and methods for developing minimum cost solutions to the principal water
quality problems.
Existing combined sewer overflow loads from Jefferson City are located
at Milepoints 18.5, 19.0 and 19.5, as shown in Figure 5-7. Rather than
treating these loads as a uniformly distributed load from Milepoint 15
to Milepoint 20, as was done in Chapter 2, it is reasonable to combine
these three discrete point source loads into one point source load
located at Milepoint 19, using the criteria presented in Section 5.2.3.3,
equation (5-2). Assuming it is desired to maintain an accuracy of
approximately 5% when aggregating these loads, it is only necessary to
check that the loads are within a distance x given by: x _<_ 0.05 U/K.
Information contained in Tables 2-3 (pg. 2-34) and 2-16 (pg. 2-81) can
be used to determine the river velocity within segment 3 at the lowest
flow condition for which the combined sewer overflows contribute a
loading to the analysis. The summer average flow satisfies this criteria
in that the time averaged combined sewer overflow load is used in this
analysis. The river velocity for this period is computed to be 8.48
miles per day. Therefore, loads within x ^0.05 (8.48)/0.20 ^ 2.1 miles
can be aggregated in computing BOD-dissolved oxygen responses in the
South River. The BOD decay rate of 0.18 per day developed in the
calibration analysis has been temperature adjusted to 25°C using Equation
(2- 7) (pg. 2-87) in this computation. Hence, it is justifiable to locate
the three CSO loads at Milepoint 19 without causing a significant
change in the results of this analysis. An additional segment beginning
at Milepoint 19 is added -to the stream in order to input the load at this
location. The segment characteristics are the same as those for segment 3.
5-33
-------
The urban runoff load from portions of Jefferson City located within
Sewer District No. 2, which was treated as a uniformly distributed load
in Chapter 2, will also be treated as a point source load in this example,
located at Milepoint 15 as shown in Figure 5-12. The hypothetical South
River example now includes 6 constant parameter segments, bounded at
Milepoints 0, 5, 15, 19, 20, 24 and 33. A summary of the geometry for
the revised model segmentation is developed from Table 2-3(b) (pg. 2-
34).
Another consideration is the impact of increasing populations during the
planning period and the consequent impact on stream flows within the
study area. This effect is minimal in the case of Sewer District No. 2
where the wastewater discharge is immediately below the water intake
point. The only difference in flow in the case is consumptive loss
which can generally be estimated as 10% of the raw water intake flow.
This flow difference is estimated to be 3 cfs.
Qn = .1 (180,000 people) x 110 gallons x 1.54 x 10~6 ^
xloss *• ' v v j person/day gpd
0, = 3.05 cfs
\Loss
The population increase in sewer District No. 1 is estimated to be
19,000 people. Thus the withdrawal flow is estimated to be:
Qcn1 = 19,000 people x 110 gallons 4 -6 cfs
XSD1 ' r r person/day gpd
Qqnl = 3.2 cfs; say 3 cfs
Ninety percent of this flow is reintroduced at Milepoint 20. The resulting
drought flow conditions in the river are summarized in Table 5-7.
5-34
-------
TABLE 5-7
FUTURE DROUGHT FLOW CONDITIONS IN THE HYPOTHETICAL SOUTH RIVER
River Flow
Segment
I
2
3
4
5
6
Milepoints
0- 5
5-15
15-19
19-20
20-24
24-33
Chapter, 2
Flows1 J
54
91
(101)
103
109
116
(cfs)
Change
-
-
-6
-
+3
_
Average Drought
54
91
95
97
106
113
(l)Table 2-16, (pg 2-81)
5.2.4.4 Computing Water Quality Response Frequency
The frequency with which extreme water quality events will occur due to
intermittent loads is generally considered to be a joint probability
function incorporating factors such as rainfall intensity and duration,
storm water flow concentrations, the interval between storms, and a
number of receiving water characteristics such as base flow, temperature,
and background concentration. Simplifying assumptions which are based
in part on observations and in part on intuitive reasoning are developed
in this section to arrive at a best estimate of the relationship between
storm related load frequency and the frequency of extreme water quality
responses.
One can show that the percent of time that rainfall occurs is simply D/A
since Zd./S . is the total duration of all rainfall events divided by
111 ,
the total time over which the record was gathered. Consider the rainfall
characteristics for the South River shown in Table 5-1(a). The percent
of time that rainfall occurs is estimated as:
P (I > 0) = D/A =(3.0/80) «100 = 3.75%
and the period without rain is:
P (I = 0) = 100 - P (I > 0) = 100 - 3.75 = 96.25%
5-35
-------
The probability that a storm related load, Wr, is less than or equal to
a given value is estimated using the following equation.
Pr(Wr £W) = Pr(I = 0) + Pr(I > 0) . Pr(Wr £W) (5-3)
This simply states that the probability that a storm related load is
less than or equal to a value, W, is estimated as the probability of not
experiencing rainfall, plus the joint probability of experiencing rainfall
having a load less than or equal to W. For example, to compute the
probability associated with a load which is only exceeded 1% of the time
in the South River example:
Pr(Wr £ W) = (100% - 1%) = 0.99
P (I = 0) = 0.9625
P (I > 0) = 0.0375
r - 0.0375 '
That is, the 99% load (that which is only exceeded 1% of the time), W,
to the river is the load associated with the 73% storm event. Similarily
the 1.5%, 2% and 3% loads can be shown to be associated with the 60%,
46% and 20% storm loads.
A major difficulty in defining statistical loads occurs when two variables
(flow and concentration) are varying. The dilemma is one in which the
probability of the loading event being exceeded is fixed and the analyst
must determine the associated flow.
Pr(Wr±W) = Pr(crQr ±W) (5-4)
If for example, the probability of a given load being exceeded is 30%,
(P (W <_ W) = . 70) , a wide range of flow-concentration combinations
exist which satisfy equation (5 -4) . The approach to the problem taken in
this manual is to assume the concentration associated with the storm
event constant, and associate all of the load variability with flow.
Therefore, P (W < W) = P (Q < Q) . These methods are intended to be
r r — r r —
for guidance purposes only and can be modified to reflect local conditions
5-36
-------
and site specific observations regarding the relationship between flow
and concentration between storm events.
5.2.4.5 Application to South River Water Quality
Equation (5-1) stated that in cases where the river flow is constant the
coefficient of variation of the response function for a particular load
is a constant for all distances downstream in a river, and is equal to
the coefficient of variation of the point source wastewater input. This
is not, however, the case in the South River where storm related runoff
events have a significant impact on the stream flow.
The 20%, 50% and 75% storm loads are used to illustrate receiving water
responses in this section. These loads are computed to occur 3%, 2% and
1% of the time from Equation(5-3). For the urban runoff loading, which
has a coefficient of variation of between 1.50 and 1.55 (Section 5.2.4.2),
the 75% load is a factor of 1.4 times the mean loading (Table 5-4). The
response due to the 75% load^may therefore be computed by multiplying
the mean load by the constant factor, 1.4, and by performing the analysis as
illustrated in Table 2-20 (pg. 2-90) and 2-21 (pg. 2-95) using this
load.
Table 5-8 presents an example calculations for the BOD response in the
South River during the peak summer storm period using the former technique.
The computation begins at segment 3 and illustrates the manner in which
the 20%, 50%, and 75% profiles due to the variable load and the constant
wastewater treatment plant load may be computed. The average flow,
cross-sectional area and stream velocity are first determined, as well
as the appropriate temperature adjusted reaction rate. The initial
concentration due to the upstream sources (L ) is then calculated from a
mass balance at the beginning of the segment.
The variable storm sewer runoff load and the constant wastewater treatment
plant load is entered at the appropriate probability levels desired,
here, the 20%, 50% and 75% levels for the storm sewer and the average
daily load for the treatment plant. Substitutution of these values into
the solutions presented in Table 2-17 (pg. 2-83), results in a spatial
5-37
-------
TABLE 5-8
REACTIVE CONSTITUENT (BOD5) SAMPLE IMPACT CALCULATION
AVERAGE SUMMER FLOW - HYPOTHETICAL SOUTH RIVER EXAMPLE
Q = 1124.0 cfs = S13 + 611 (Tables 2-16, S-3)
A = 1596.4 sq. ft.
U = (Q/A) . (16.36) = 11.51 mi/day
K = O.-25/day e 25°C
Segment 3 - Milepoints 15.0 - 19.0
L = Upstream BOD,. = 3.03 mg/1
L0 = (L0) • (Qj/Qj) = (3.03) • (451/1124)
=1.21 mg/1 (Upstream Q = 451 cfs (Table 2-16))
Wys = 75% load = 1.4 x mean load = 89200 Ib/day (Table 5-4)
W = 89200 + 7606 = 96806 Ibs/day (Tables 5-4, 5-5)
(Storm) (Point)
w = 416 Ib/mi • day (AG + FOR) (Table 2-15)
Rewriting Equations of Table 2-17 with conversion factors for units,
-Krx/U -Krx/U -Krx/U
L(x) = LQe + (W/5.4Q)e + (3.04 • w/(A • K )) • (1 - e )
for MP 15, X = 0;.' US) = 1.21 e-°-25(°)/ll-51 + (96806/(5.4) • (1124.)) e--25(°)/"-5l
+ (416) • (3.04/1596.4 • 0.25)) • (1 - e-°-25(0)/U.51j
L(15) = 1.21 + 15.95 + 0.00 = 17.16 mg/1
for HP 19", x = 4; L(19) = 1.21 e-°-25C'')/ll-51 + (96806/(5.4) (1124)) e--25(43/H-Sl
+ (416) • (3.04/(1S96.4 • 0.25)) • (1 - e-0.25(4)/11.51j
L(19") = 1.11 + 14.62 + .26 = 15.99 mg/1
Since the storm sewer load is a transient load, 15.99 mg/1 overestimates the expected response at HP 19.
Dispersion will diminish the response-due to the storm sewer load in the manner shown in Figure 5-4.
This effect may be included by considering the response due to the storm sewer load alone, both with
and without dispersion.
In this case,
E = 1 mi2/day
d = 4 hrs = 0.167 days
, 2Et _ 2(1.0) (.431)
dU (.167) (11. Sir
Prom Ficurc ' 4 Concentration wi
irom ligurc . 4, Concentration wi
The response at MP 19 due to the
w -Krx/U 89200 -
5.4Q " 5.4(1124) e
The concentration with dispersion
The difference, 13.5 - 9.45 = 4.0
reduce the response due to the st
dispersion on the transient storm
estimated as 15.99 - 4.05 = 11.94
A similar procedure is carried ou
taken to account for the effects
the SS and CSO loads.
x = 4 mi.
U = 11.51 mi/day
t'= X/u + d/2 = .431 days
3
th dispersion
thout dispersion
storm sewer, without dispersion, is given by:
. 25(4)/11.51
=0.7 (13.5) = 9.45 mg/1.
5 mg/1 is the amount by which dispersion will
orm sewer. Hence, including the effects of
load, the BOD concentration at MP 19 can be
mg/1.
t for segments 4,5 and 6, with care being
3f dispersion on the response due to both
800
BOD
DISPLAY OF STORM LOAD
RESPONSE IN THE
SOUTH RIVER
AT HP IS
/ft ^— »TOa» LOAO RESPONSE
ft/ C,.I5.3.,/I
yy
4HSS.1
-i-i)
AT HP. 19
T r i
I 1 | C,.|J.JUS/I
1 I j C«* t.49 Ml/1
C2/C,=.70
5-33
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TABLE 5-8
(Continued)
COUPLED SYSTEM (BOD-DO) SAMPLE IMPACT CALCULATION
AVERAGE SUMMER FLOW ANALYSIS
HYPOTHETICAL SOUTH RIVER EXAMPLE
Sc|«cnf 3 - Milepoints 15. 0 - 19.0
Q • 1124.0 cfs - 513 « 611 (Tables 2-16. 5-3) Kd * Kr " 0>2S * 25°C
A- 1596.4 sq. ft. lf . 12.96 U1/2 (£t/see)/H3'2(ft)
H « 5.39 ft. « 12.96: 701/2/4.433/J • .869/day I 20°C
U • (Q/A) • 16.36 - 11.51 ni/day ^ - .869 (1.024T"2°) - . 869(1. 024S) • .98/day t 2S°C
*r • 0.25 « 25°C
Def: DO - (D0) • (^/Qj » (.S82) • (451/1124) > .27 ng/1 (0^ « 451. Table 2-16)
CBOD: L0 » U0) • V'l " C3'03) " £451/1124) - 1.21 ag/1 V
V ' 7606 « 89200 * 96806 Ib/dayCPoint Source + Storn Source) (Tables 5-4, S-S1
(Point) (Storm)
U - 416 Ib/al • day (AC * FOR) (Table 2-15)
MEOD: 1 « 0
o
X - 5070 "» 3800 - 8870 lb/day(Point » Stora Source) (Tables 5-4, S-S)
w - 0 (Assuming AC + FOR non-reactive)
UOD: t0 - 1.21 • l.S * (0) • 4.57 » 1.81 mg/1
X • 96806 • l.S * 8870 • 4.S7 - 185,740 Ibs/day
w - (416) • l.S » (0) • 4.S7 - «24 Ibs/mi • day
Rewriting equations of Table 2-17 with conversion factors for units:
-tx/u «, -V/" ""a*/" r. -V/u -
« Do e * 10 • f-$--& ) * (K/Q ' S.39) •
At W IS, x - 0, DO - .27 Dg/1 and D.O. -7.9 og/1
At HP 19", X » 4",
0(4-) - .27 .-9»C«)/».S1 . j.gj ^.25^^ (e-2S(4)/ll.Sl.e-.98(4)/ll,Sl)
(18S740./(1124. . 5.4)) . ^^ (e-.2St4)/II.SI .
3.04 . C . -.98C4)/H.Sl.e-.2S(4)/ll.Sl
D(4") • .192 » .127 * 2.1528 * .016 • 2.49 Bg/1
D.O. - 8.17 - 2.49 > S.68
This D.O. level is somewhat lover than might actually be expected, since the analysis thus far does not
include the effects of dispersion on the transient stom sewer load. The deficit response to the
itora'sever load alone, at HP 19, without the effect of dispersion is determined as follows:
v . 89200 • l.S » 3800 • 4.57 - 150870 Ibs UOD/day
Substituting this value of M into the third tcru of Equation 2-17, the deficit at HP 19 due to the SS
is determined to be 1.75 ng/1
Froa the exanple BOD calculations, previous pace, the expected response with the effects of dispersion
included was shown to be 70\ of the non-dispersive case, or .7(1.75) • 1.22 Bg/1. Hence, the difference
of 1.75-1.22 • .53 »;/l is the amount by which the steady state plug flow analysis overestimates the
expected oxygen deficit. Using this information, the computed deficit at MP 19 becomos:
0(4") • 2.49 - .53 • 1.96 mg/1
D.O. • 8.17 - 1.96 . 6.21 mg/1
Similar calculations arc made for segments 4, 5 and 6. Note that the SS and CSO loads must be
handled Individually to account for the effects of dispersion.
5-39
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distribution of five day BOD within the segment being analyzed. Similar
computations follow for the remaining -segments, with care being taken to
carry the appropriate concentration and flow values for a given probability
level through to the end of the study area. The dissolved oxygen response
has been computed in a similar manner. Care must be taken to attenuate
the effects of the transient storm sewer and combined sewer overflow
loads, so as to account for the effects which dispersion has on them.
The procedure for doing this is described in Section 5.2.3 and illustrated
in the example calculations as well. These computations are illustrated
for one river segment in Table 5-8. The computed dissolved oxygen
concentrations for the South River study area are presented in Figure 5-
10.
5.2.4.5.1 Dissolved Oxygen Concentration - Drought
Flow Periods
Drought flow conditions in the South River study area are found to be 50 cfs
for the 7 consecutive day-10 year low flow at the upstream end of the
study area. During these periods only dry weather discharges
from municipal and industrial sources and tributaries contribute oxygen
demanding substances to the receiving waters.
The projected water quality response in the South River is indicated in
Figure 5-11. Figure 5-11(a) shows the dissolved oxygen concentration
relative to the water quality objectives for the study area at the end
of a 20 year planning period. A highly probable water quality problem
is indicated in the figure. Dissolved oxygen concentrations are expected
to approach 0.0 mg/1 in the region between Milepoints 20 and 25 and the
entire region between Milepoint 17 and 33 is expected to be below the
water quality objective level.
Figure 5-11(b) indicates the impacts due to specific discharges. Municipal
wastewater treatment plant No. 2 is the largest single contributer to
the problem contributing 65% of the total response at the critical
location, Milepoint 23. The industrial discharge and tributary inflow
have a minor impact on the projected dissolved oxygen conditions.
5-40
-------
O>
E
Z
LU
(S
i
Q
tlJ
>
O
12
10
8
6
4
2
(a)
SUMMER STORM PERIODS
TEMPERATURE:25°C
BASE FLOW = 250 CFS
MTURJXTJON ^SJITiitt^l
P.O. STANDARD
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
30
35
o>
E
o
u.
tlJ
a
LJ
to
X
o
o
LJ
O
CO
CO
6W/ 7" RESPONSE ANALYSIS
MEAN STORM LOAD
NOTE:
REPRESENTS DISSOLVED OXYGEN DEFICIT
CONCENTRATION WHICH WILL ONLY BE
EXCEEDED 1.2% OF THE TIME.
COMBINED SEWER
STP.NO.2
..
STP. NO.
BACKGROUND SUPSTREAM
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
SOUTH RIVER
FIGURE 5-10
PROBABILISTIC ANALYSIS OF WET WEATHER DISSOLVED OXYGEN
HYPOTHETICAL SOUTH RIVER
5-41
-------
o>
E
UJ
X
o
o
Ul
o
co
co
Q-5O CFS (7DAY-IO YEAR FLOW)
TEMPERATURE^ 2S°C
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
O
u.
UJ
o
UJ
o
X
o
o
UJ
o
CO
CO
DROUGHT FLOW- UNIT RESPONSE ANALYSIS
NO DISTRIBUTED SOURCES
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
SOUTH RIVER
FIGURE 5-11
DRY WEATHER DISSOLVED OXYGEN ANALYSIS
HYPOTHETICAL SOUTH RIVER
5-42
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5.2.4.5.2 Nutrient Enrichment-Average Summer
Conditions
Nutrient enrichment in the South River study area was noted to be a
potential water quality problem in Chapter 2. Because nutrient impacts
tend to be on a longer time scale, the analysis was made using average
summer flows, the long term average summer storm loads (W ), the point
sources, and upstream and background effects. As indicated in Equation
3-21, W = WDD/A, and D/A = 0.0375 during the summer in the South River
O K
area, that is, it rains only 3.75% of the time. The results developed from
the equations in Table 2-17 are presented in Figures 5-12(a) for total
nitrogen and 5-12(b) for total phosphorus, where the components of the
nutrient response due to various loads within the study area are shown. The
predicted peak concentrations of 3.95 mg N/l and 1.40 mg P/l are considerably
higher than those required to indicate a probable problem.
Figures 5-12(a) and 5-12(b) show that point source loads are expected to
be the largest single source of nutrients to the system at the end of
the 20 year planning period. Therefore, nutrient removal at one or both
of these plants appears to be a potential solution to the problem, if
further analyses of nutrient-phytoplankton dynamics (using methods
described in Appendix A) demonstrate a need for nutrient reductions.
Such an analysis would indicate the nutrient which should be removed as
well as the nutrient levels required to maintain an objective phytoplankton
level.
5.2.4.5.3 Total Suspended Solids-Summer Storm
Periods
Expected total suspended solids concentrations in the South River using the
solids decay rate of O.I/day (pg. 5-8) during the 20%, 50%, mean (68%) and
75% summer storms are shown in Figure 5-13(a). These results indicate a
probable problem during summer storm periods. The smaller (i.e., 20%) storms
have a smaller impact at Milepoint 15, the location of maximum concentration.
The river concentration increases further downstream during these storms,
however, due to the continual inflow and background load, with the smaller
5-43
-------
en
E
AVERAGE SUMMER CONDITION INCLUDING
O.O37S If MEAN SUMMER STORM LOAD
LONG TERM STORM LOADS
BACKGROUND aUPSTREAU
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
(b)
01
E
AVERAGE SUMMER CONDI TION INCLUDING
O. O37S # MEAN SUMMER STORM LOAD
<
O
LONG TERM STORM LOADS,
BACKGROUND 8 UPSTREAM
STP. NO. 2
STP. NO. I
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
SOUTH RIVER
30
35
FIGURE 5-12
LONG TERM TOTAL NUTRIENT IMPACTS
HYPOTHETICAL SOUTH RIVER
5-44
-------
500
400
C 300
^
en
e
CO
CO
en
£
200
100
(a)
SUMMER STORM PERIODS
BASE FLOW'290 CFS
V
\\
\ \
\\
^ V-
-7S% STORM
•MEAN STORM
20% STORM
S0% STORM
1
L
300
250
200
150
too
50
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
(b)
30
MEAN LOADS
_ URBAN SOURCES
COMBINED
SEWER-
STORM SEWER
I
J_
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
SOUTH RIVER
30
35
35
FIGURE 5-13
WET WEATHER TOTAL SUSPENDED SOLIDS IMPACTS
HYPOTHETICAL SOUTH RIVER
5-45
-------
diluting flow in the river. It should be noted' that the storm impacts are
also reduced to compensate for dispersion effects as indicated in Figure 5-4.
The component contributions of the urban sources of total suspended
solids during the mean storm are shown in Figure 5-13(b). The municipal
treatment plant loads have a negligible impact on the total suspended
solids, while the problem is in large part due to storm sewer sources.
Another major contributer to the problem is upstream and background
sources from agricultural lands which contribute 30 percent of the total
observed response at Milepoint 15 during the mean storm. The results
indicate a possible need to evaluate control of both non-urban and urban
non-point sources of total suspended solids to control the problem.
5.2.4.5.4 Total Coliform Concentration-Summer Storm
Periods
Figure 5-14 demonstrates for the coliform die-away rate of 1.26 (pg. 5-8)
the 20 year projections for total coliform concentrations in the South Riv.er
during the 20%, 50%, mean (68%) and 75% storms. Very high concentrations
are predicted at Milepoint 19, the location of the combined sewer area load,
indicating a highly probable problem. The peak concentration during the mean
storm is about 1,200,000 MPN/100 ml. '
The mean storm unit response for total coliform organisms is shown in
Figure 5-15. The combined sewer systems in sewer District No. 1 contribute
heavily to the problem followed by the separate sewer areas. Note that
the logarithmic scale used in Figures 5-14 and 5-15 make comparisons of
different storm responses difficult, with small vertical differences
towards the top of the figures representing large differences in total
coliform concentrations, while larger vertical differences towards the
bottom of the figures represent small actual differences in total coliform
concentrations.
5-46
-------
o
o
0.
2
K.
O
O
O
1,000,000
500,000
1 00,000
50,000
10,000
5,000
1,000
500
100
SUMMER STORM PERIODS
BASE FLOW = 250 CFS
^
•••
y-
v
1t% STORM
75% STORM
\< i\
l/v-J \
STORM
STORM
STORM
5 10 15 20 25 30
MILES BELOW ROUTE 80 BRIDGE
SOUTH RIVER
35
FIGURE 5-14
WET WEATHER TOTAL COLIFORM CONCENTRATIONS
HYPOTHETICAL SOUTH RIVER
5-47
-------
3,000,000
1,000,000
500,000
o
o
OL
u
o
o
_J
o
I 00,000
50,000
10,000
5,000
1,000
500
100
UNIT RESPONSE ANALYSIS
MEAN STORM LOAD
STORM SEWER-
STORM SEWER
COMBINED
SEWER
UPSTREAM ft BACKGROUND
I
I
I
J_
I
10 15 20 25 30
MILES BELOW ROUTE 80 BRIDGE
SOUTH RIVER
35
FIGURE 5-15
UNIT RESPONSE TO MEAN TOTAL COLIFORM STORM LOADS
HYPOTHETICAL SOUTH RIVER
5-48
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5.3 Estuaries
Estuaries are those water bodies in which a significant hydrodynamic
transport mechanism is mixing caused by astronomical tides and other
similar mixing mechanisms. Estuaries normally consist of two sections
which are characterized by the relative magnitude of advective flow to
tidal mixing or dispersion. In purely estuarine systems the downstream
portion is normally dominated by tidal mixing and freshwater advective
flow is less important in transporting physical and chemical
constituents. The upper reaches of the estuary are usually influenced by
tidal action to a lesser degree because of the damping effect of bottom
drag within the estuary, this portion of the estuary is referred to as
a tidal river and is characterized by a significant advective transport
component.
The analysis of water quality in one dimensional estuaries is somewhat
more complicated than in streams principally because of tidal mixing.
Materials that are discharged at one point in the system affect water
quality in both the upstream and downstream direction because of tidal
reversals. The classical method of incorporating this mixing transport
in estuaries, and one which finds wide use in engineering practice
today, is through the use of dispersion coefficients, normally designated
by E. In practice the dispersion coefficient is an estimator of the net
rate at which mass is transported from regions of high concentrations to
regions of low concentrations. The effect of dispersion is to spread
materials discharged to the estuary in the longitudinal direction both
upstream and downstream. Due to this phenomenon, a segmented model of an
estuary requires simultaneous solution for all segments. The simplified
stream analysis, in which upstream concentrations are independent of
downstream effects, is not applicable.
Estuaries also differ from streams in the time scale of their response
to continuous and intermittent loadings. Generally the response time to
loadings is longer in estuaries than in streams. For example, after a
continuous source begins discharging into an estuary, concentrations
will build up for several days to several weeks before a steady state
5-49
-------
value is achieved. This is in contrast to advective systems where the
concentration buildup at the discharge point is immediate, and equal to
the mass balance concentration between the stream and the discharge.
Intermittent loads-are also acted upon differently in estuaries. Pollutant
concentrations due to pulse loads are quickly attenuated because of
longitudinal mixing.
This section of the manual considers methods for evaluating water quality
responses in estuaries and tidal rivers. The analysis is structured for
preliminary assessments similar in design to the preliminary water
quality assessment methods for streams presented in Chapter 2. These
methods are useful to the 208 planner in the initial development steps
of the 208 water quality management plan, and will provide him with a
broad overview of water quality problems, the relative magnitude of
various waste sources, and the probable impact of the various sources on
water quality. From that point the analysis can proceed toward the
selection and implementation of appropriate technical procedures to
analyse waste sources which are important in the planning area. These
technical procedures may be numerical computer models or more refined
extensions of the analysis procedures demonstrated in this manual.
In this Chapter, then, all estuarine analyses will be performed on a
constant parameter simulator of a real system for which analytic solutions
are available. If significant variations in flow, cross-sectional area,
dispersion coefficients and kinetic rates, etc. occur within the study
area, and if the results of this simplified analysis indicates potential
water quality problems, a more sophisticated analysis framework - outstide
the scope of this manual - is required (Appendix A).
The basic equations for calculating waste concentrations in estuaries
and tidal rivers are presented along with guidance for the determination
of model coefficients. Example problems are presented to demonstrate
the analysis methods for point and non-point- sources. Finally Section
5.3.4.1 presents empirical methods for assessing water quality variability.
The examples presented in Section 5.3.4.1 are applicable to many local
problem cases and should be taken as instructive tools illustrative
of techniques which the 208 planner may follow.
5-50
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5.3.1 Description of Model
For purposes of this chapter, a tidal river is defined as that portion
of a water body that is subject to reversals of current direction but
does not include estuaries where the effects of freshwater runoff may be
small. Thus, tidal rivers that may oscillate in velocity and direction
due to causes other than astronomical tides are included in the analysis.
An example of the latter case is the flow oscillations in the tributaries
of the Great Lakes caused by wind produced seiches. Estuaries are those
water bodies that are dominated by tidal dispersion.
The appropriate general steady state solutions for the tidal rivers and
estuaries are presented in Table 5-9 through 5-11 for conservative,
reactive and sequentially reactive system variables (7). The reaction
coefficient, K, is descriptive of the particular substance under consideration.
The velocity, U, is that due to the freshwater discharge. The tidal
velocity is not included in the equations, implying that water quality
conditions are at mean tide.
The coefficient, E, is the longitudinal dispersion coefficient. It is
most significant in the saline portion of the estuary where a number of
factors contribute to the intrusion of the salt into the estuary. The
concentration of other substances, which are of concern in water quality
analyses of estuaries, is affected in a manner similar to that of the
salt. In the tidal, but non-saline sections of the river, the dispersion ~
although not as pronounced as in the saline section -- is still a
significant factor in the analysis of water quality.
As pointed out previously, the equations for calculating receiving water
concentrations (Table 5-9) are applicable to constant parameter estuaries.
For gradually varying areas, flows, etc, averaged values are to be input
to the equations for preliminary problem assessments.
5-51
-------
tn
I
tn
to
TABLE 5-9
STEADY STATE EQUATIONS FOR WASTE CONCENTRATIONS IN TIDAL RIVERS AND ESTURIES DUE TO POINT SOURCE
"long" estuary
_E,A,K. constant
Type Waste
Conservative
Reactive
(System 1)
Sequentially
(System2)
x £ 0
C . Coe«^
gjX
L = V
K., g,x 082X
D 12 T fc * m' e 1
D K2-K Lo tc m2. J
x = 0
CQ = W/Q
LQ = W/CQm,)
n .12. . r n mii
uo " K2-Kj Lo u ' m2J
x >_ 0 ,
C=Co=W/Q /
(
h*
L=LQe ^X
D _ K12 V Bl -i2x.
K2-K1 ov D12
_ _ _fmi 1-niz - U , . c
XC - nW rsT ^ Cmz-mi)
5
^^
0
\^~^
)
DESCRIPTION OF SYMBOLS WITH TYPICAL UNITS
Q = flow (cfs)
U = velocity = S (fps)
A = cross-sectional
area (ft )
Kj = decay rate, system 1 (e.g. BOD) (day )
K2 = reaction rate, system 2 (e.g. reaeration rate)
K,2 = reaction rate between systems 152, (e.g.
deoxygenation rate K.) (day" )
j± = (U/2E) (1-m.)
gi = CU/2E)(1 +m.)
E = dispersion coefficient W = mass discharge rate (Ib/day)
(miVday)
-------
TABLE 5-10
STEADY 'STATE EQUATIONS FOR WASTE CONCENTRATIONS IN TIDAL RIVERS AND ESTUARIES
DUE TO DISTRIBUTED SOURCE
T>pe of waste
Conservative
Reactive
(Systen 1)
Sequentially
Reactive
(Systea 2)
1 1 1 1 1 1 1 1 W (Ib/day/ai) |
...—*- Q | .- x QiEiAfKj wo constants
h a ' a '
C . H S. eu/E(x»a)_eu/E(x-»)
g.(x*a) g.(x-a)
L • ~~ e -e
"Vl
K12 <)f:l(x"1>_eMX-a>
Q Kj-Kj Bjgj^
e -e
V,
„., ..f.^,-.— -.,
Ji(x»a) g.(x-a)
w e1 -le1 -1
,, J,(x»a) g,(x-a)
w K12 e -1 e -1
e 2 -1 e 2 -1
-^
L ' Q^ e
„ H K12 e J "*S -e J * *
D"«V=i Vi
J,(x*a) j,(x-a)
e -e '
V*
Distribution of Estuarlne Haste Concentrations
l-'-j-M
ri 1 i r i~
^^
^-
c
-a2-
-oo+o X
rrri i n
^
tr^-
-• _ "H , x
X,>o/nil,0
-------
TABLE 5-11
LOCATION OF MAXIMUM CONCENTRATION FOR DISTRIBUTED SEQUENTIALLY REACTING WASTE
• (d D/dx)
2ajj 2aj,
SHOWN FOR CA9C X.
e -1 e -1
Value of s
I Positive
II Negative
III Zero
Location of D^
xc>a
xc
-------
5.3.2 Methods of Analysis
5.3.2.1 Conservative Substances
The analysis for conservative substances is identical to that for streams.
The maximum concentration at the point source discharge location is
simply the mass rate of waste discharge divided by the freshwater flow (Table
5-11):
Note that upstream migration of the waste occurs.
Equation (5-5) may be applied to substances such as total dissolved
solids, and other materials which decay at such slow rates that they may
be regarded as conservative.
5.3.2.2 Non- conservative Substances
Many substances decay in accordance with a single reaction or at least
for practical engineering purposes may be assumed to decay in this
fashion. As discussed previously, the reaction is assumed to be first
order with a decay coefficient, K.
It should be noted that the following assumptions have been made:
a) steady state
b) constant coefficients exist, i.e., flow, cross-sectional area,
reaction kinetics and dispersion characteristics are all
constant along the length of the estuary under study.
Since most estuaries vary in cross section along the axis of flow this
area must be estimated as the average over which the profile extends at
mean tide. For highly reactive substances (K _> 2/day) this distance may
be in the order of 10 or 20 miles, while for moderately reacting material
(K _< 0.5/day) it may be as much as 50 miles. The difficulty in assigning
a realistic average area over such distances is evident from a casual
inspection of a geographic map of the coastal areas of the United States.
A common physical feature of the topography not taken into account by
5-55
-------
the above model is the number of tributaries which feed many estuaries
and the delta network which characterizes many estuarine mouths.
Obviously, a more complete mathematical description of the estuarine
structure is required for such situations. In spite of these difficulties,
at least, some engineering approximation may be made and the error
introduced is invariably on the conservative side.
Table 5-12 presents ranges of values for reaction coefficient in tidal
rivers and estuaries for the pertinent substances.
TABLE 5-12
FIRST ORDER RANGE OF VALUES FOR REACTION COEFFICIENTS
. TIDAL RIVERS AND ESTUARIES (8)
Substance K-per day K-per day
Coliform 2-4 1-3
BOD5 0.2 - 0.5 0.2 - 2.0
Nutrients 0.1 - 0.25 0.1 - 1.0
or conservative
(K = 0)
From Table 2-19, for rivers.
5.3.2.3 Dissolved Oxygen Analysis
The analysis for dissolved oxygen is conducted in a .similar manner. The
waste discharge causes a drop in the dissolved oxygen concentration with
a subsequent rise further downstream. The tidal river profile is therefore
similar to that of the stream. Due to the tidal action, however, the
deficit in dissolved oxygen is translated upstream and the associated
dispersion flattens the profile. The tidal river profile is therefore
projected further upstream and downstream in contrast to the stream
profile. The equation of the dissolved oxygen deficit evaluation in
estuaries is shown in Table 5-11. As may be seen from these equations
the dissolved oxygen deficit profile is determined by the ratio, , and
also the parameter n. The following sections relate to a discussion of
these factors.
5-56
-------
5.3.2.4 Reaction Coefficients
As in the case of the freshwater stream, the surface transfer coefficient,
KT , is a fundamental expression of reaeration phenomenon particularly
L
appropriate to estuary analysis. It is related to the volumetric reaeration
coefficient by the depth.
KL
K - - (5-6)
where: K " is the surface transfer coefficient (ft/day) (Figure 2-20)
JLi
H is the average depth at mean tide (ft.)
K is the reaeration coefficient (I/day) .
a
The reaeration coefficient is a function of the velocity and depth of
flow. In the tidal river and estuarine case, the pertinent velocity is
the average tidal current. The ranges of transfer and reaeration
coefficients which may be encountered in estuaries are presented in
Table 5-13.
TABLE 5-13
RANGE OF TRANSFER AND REAERATION COEFFICIENTS
ESTIMATED FOR TIDAL RIVERS AND ESTUARIES (8)
(K, in ft/day, K in I/day)
Jj _ cl
Average Tidal Velocity (fps)
1 1-2 2
Mean Tidal
Depth (ft)
10
10 - 20
20 - 30
30
KL
4
3
2.5
2
K
a
0.5
0.2
0.1
0.06
KL
5.5
4.5
3.5
2.5
Ka
0.6
0.3
0.14
0.08
7
6
5
4
K
a
0.8
0.4
0.2
0.12
The probable range of K is between 3-6 feet/day with limits from 2 to
L
a possible 10 feet per day for a shallow estuary with high tidal velocity.
Anticipating the effect of treatment on the oxidation in the natural
estuarine environment, the range of the deoxygenation or deaeration
5-57
-------
coefficient, K,, may be from 0.2 - 0.5 with a probable average .in the
order of 0.3, (See Table 5-12). This range assumes that the estuary is
no shallower than about 5 feet.
The assimilation ratio, , may readily be tabulated from the above data
and is summarized in Table 5-14 for different conditions.
TABLE 5-14
TABULATION OF ASSIMILATION RATIO -
TIDAL RIVERS AND ESTUARIES (8)
Reaeration Coefficient ,
a *•'•'•'
0.08
0.15
0.30
0.60
K= 0.2
0.4
0.75
1.5
3.0
0.3
0.27
0.50
1.0
2.0
0.4
0.20
0.38
0.75
1.5
0.5
0.16
0.30
0.60
1.2
Tables 5-13 and 5-14 indicate that the deeper main channel estuaries
have 4> values from 0.2 to 0.8, while the shallower tidal tributaries are
in the range 0.8 to 3.0. The lower limit of each of these ranges indicates
the more restricted tidal bodies of lower velocity, higher temperatures,
and effluents from less advanced degrees of treatment, while the upper
limit describes the free flowing, higher velocity estuary, and more
advanced treatment in more moderate temperature regions of the country.
5.3.2.5 Estuarine Number
In addition to the assimilation ratio, 4", the estuarine number, n =
2
KE/U , is the additional specification which characterizes water quality
in tidal rivers and estuaries. The practical range of the dispersion
2
coefficient, E, is from 1 to 20 (mi /day). The upper limit describes
the highly-saline, high-tidal-velocity stretches in the vicinity of the
estuarine mouth, while the lower limit applies to the upstream, non-
saline, low tidal sections of the estuary. If slack water longitudinal
profiles of salinity or chlorides are available, an estimate of the
dispersion coefficient may be obtained. 'This is accomplished by plotting
5-58
-------
the salinity vs. distance on semi-log paper, fitting a straight line to
the data and obtaining E, as described in Reference (7). The dispersion
coefficient, E, with the advective velocity, U, provides sufficient
hydrodynamic definition for each estuary. The advective velocity
associated with the freshwater flow is determined by dividing the
freshwater flow, Q, by the average cross-sectional area, A. The dispersion
coefficient may therefore vary over a wide range due to the number of
geophysical and hydrological factors which affect it, not only within
the estuary itself, but also by the characteristics of the drainage
basin. The advective velocity U, may range from 0.1 - 10 miles per day.
The estuarine number, n, developed from this range of advective velocities
and a practical range of dispersion coefficients is tabulated in Table
5-15 for a reaction rate of 0.3/day. For wastes with higher reaction
rates, the estuary number increases accordingly. Thus, for coliform
bacteria with a decay rate of 3/day, the estuary numbers, n, would be
ten times the values tabulated below.
TABLE 5-15
RANGE OF ESTUARINE NUMBER, n,
FOR TIDAL RIVERS (8}
K = 0.3/day
Advective velocity - mi/day
0.5
1.0
2.0
4.0
Tidal Dispersion
(sq. mi/day)
2
5
10
20
A summary of the above tabulations with approximate physical descriptions
of the types of tidal rivers and estuaries is presented in Table 5-16.
2.4
6.0
12.0
24.0
0.6
1.5
3.0
6.0
0.15
0.38
0.75
1.5
0.04 "
0.10
0.19
0.75 -
= n
5-59
-------
TABLE 5-16
CLASSIFICATION OF TIDAL RIVERS AND ESTUARIES (8)
(K=0.3/DAY)
Description '
Large, deep, main
channel in vicin-
ity of mouth
Moderate naviga-
tion channel, up-
stream from mouth
saline, large ti-
dal tributaries
Minimum naviga-
tion upstream,
smaller saline
or nonsaline ti-
dal tributaries
Tidal tributaries,
shallow and non-
saline
Assimilation
Ratio
KE
2
Estuary Number
'n'
YJ (mi /day"
Average Aver. Aver.
Value Range Value Range Value Range
0.3
0.5
1.0
2.0
0.1-0.5
0.2-1.0
0.5-2.0
1.0-3.0
10 5 -20
2-5
1.5 1-2
.5 .21
15 5-30
2-10
0.5-5
0.2-2
5.3.3 Examples of Estuarine Analyses
Examples of impact evaluations of single point source and multiple waste
sources on estuaries are presented below. All analyses are carried out
using the steady state equations of Table 5-10 for calculating waste
concentrations in estuaries with constant geometry, hydrology and kinetics
and having continuous pollutant inputs. For study areas having
significantly varying geometry, flows or kinetic rates (e.g., reaeration
coefficients), appropriate analyses may be conducted to determine the
sensitivity of the result to the varying parameters. Thus, if the
cross-sectional area varies widely, analyses can be performed for low,
medium and high estimates of the constant area for the entire length
of the estuary. If sufficiently diverse results occur under fhe three
assumptions, and if the interpretation of the differences in water
5-60
-------
quality response show the existence of a water quality problem in one
case and the lack of a potential problem in the estuary in another case,
a more detailed analysis using computerized models is required. On the
other hand, if the impacts vary little and the interpretation of the
water quality results is consistent, relative confidence in the analysis
.results and management decisions may be made based on this simplified-
approach.
Use of the steady state framework will yield accurate results when
reasonably continuous waste sources exist. For intermittent inputs
(e.g. storm overflows}, the calculated.concentrations will generally be
higher than those that would result from a more rigorous time variable
analysis. For short-term inputs (several hours}, the steady state
analysis may significantly overestimate the estuarine impact, whereas
for longer areawide storms of several days duration reasonably accurate
impacts are usually predicted. Since the steady state analysis generates
conservative results, its use as a preliminary screening device for
relative impacts of waste sources is useful. If continuous sources are
cited as the dominant cause of deteriorated water quality, the analysis
may be considered as a valid input to management decisions. In those
cases where problems are attributable to intermittent sources, care must
be exercised in using the results. Where predicted estuarine
concentrations are several orders of magnitude above desired levels (e.g.
coliform bacteria}, the implication of the intermittent source as a problem
may be made with confidence. In marginal cases, time variable analysis is_
required - a topic beyond the scope of this manual.
5.3.3.1 Example of an Estuary Analysis with a Single Point
Source
Table 5-17 contains low flow and summer average flow analyses for a
continuous point source discharge. A secondary municipal STP is assumed
with an effluent flow of 10 cfs and effluent concentrations of total
nitrogen (assumed conservative), total coliform and ultimate oxygen
demand consistent with data in Table 2-10 (pg. 2-53},
5-61
-------
on
i
ON
Actual
Idealized
TA£LE 5-17
EXAMPLE OF ESTUARY WITH SINGLE POINT SOURCE
b) Total Coliform Concentrations (Reactive)
Estuary Number n = KcE/U2 = 2/day x 2 mi2/day * CO-41 mi/day)2
n s 23.8
0, H, A, E, Ki constant
Freshwater Flow (Q)
Low Flow = 50 cfs
Summer Av. = 300 cfs
Mean Water Depth (H) = 10 ft.
BOD-DO:
= 0.25/day
K12 = Kd = Kr
Coli: K,
2/day
1 c
Av. Cross Sect. Area (A) = 2000 sq. ft. Point Source Flow: 10 cfs
Av. Tidal Velocity (U?) = 0.6 knots PS Effl. Cone: 20 mg-TN/1,
Dispersion Coeff. (E) = 2 mi2/day
120 mg-UOD/1,
1000 MPN/100 ml Tot. Coli.
LOW FLOW ANALYSIS
2
Av. Freshwater Velocity = oyA = SO cfs T 2000 ft = 0.025 fps
U = 0.02S fps x 16.4 x 16.4 ml/fdaY = Q.41 mi/day
a) Total Nitrogen Concentrations (Conservative)-
W = 10 cfs x 20 mg/1 x 5.4 W**?/. » 1080 lb/day
Slax = C 8 x = 0, CQ = W/Q
(Table 5-9)
CQ = 1080 lb/day f (SO. cfs x 5.4) = 4.0. mg-TN/1
2
Upstream of Point Source
C . CQ e"*/11 = 4.0 et°-41 mi/day * 2 m"/d0^ * Oni) CTaMe s.gj
C = 4.0 e°-205x, x < 0
m =/l + 4m = /I + 4 x 23.8 = 9.81
j = (U/2E)(l-m) = (0.41/(2x2))Cl-9.81) = -0.903/mile
g = (U/2E)(l+m) = (0.41/(2x2))(l+9.81) = + 1.108/mile
Total Coli. Discharge = Wcoli = 1 cfs x 1,000 MPN/100 ml
Max. T. Coli Cone, is @ x = 0: (Table 5-9)
, _ , _ w/0m _ 10 cfs x 1,000 MPH/100 ml .
W Lo ~ W/Qml 50 cfs x 9.81 20
Upstream of PS, L = LQ egx = 20 e1<108x,.x <_ 0 (Table 5-9)
Downstream of PS, L = L <
.
ml
20 e-°-90at. x > 0
c) Dissolved Oxygen Deficit Concentrations
UT - Av. Tidal Vel = 0.6 (knots = SSH^JSi, x 1.15
MW depth = 10 ft, KL = 4 ft/day;
K =
= KL/H = 4 ft/daX *
0.4/day
0.25 x 2/C0.41) = 2.974; ni = /I + 4 ii = 3.591
n = K E/U2 = 0.4 x 2/C0.41)2 = 4.759; m,
(U/2E)(l-m1)=(0.41/(2x2))(l-3.S91) = -0.266/mile
(U/2E)(l-m2)=(0.41/C2x2))Cl-4.476) = -0.3S6/mile
(U/2E)(l+m1) = C0.41/(2x2))Cl+3.591) = +0.471/mile
CU/2E)(l+m2) = C0.41/(2x2))U+4.476) = +0.561/mile
. = 1.0 fps-
-------
TABLE 5-17
(Continued)
EXAMPLE OF ESTUARY WITH SINGLE POINT SOURCE
tn
I
Ultim. Oxygen Demand Discharged = 10 x 120 x 5.4 = 6480 Ib/day
Max, DO Deficit Occurs 8 x.a
m 1 m "
m. i-ni- ..
T5
(Table 5-9)
xc = 0.07354/0.09071 = 0.811 miles
12
0.25
(e
UOD
Qm,
(Table 5-9)
6480
•(e
-0.266x0.811
0.4-0.25 50x5.4x3.591
11.14 (0.2049) = 2.28 mg-DEF/1
3.591 -0.356x0.811.
4^76 C >
D = 11.14 (e0-471 -0.802 e°-561x), x <. 0 (Table 5-9)
11.14
-0.802 e--), X>0
SWfrER AVERAGE FLOW ANALYSIS
Assume no signif. geometric changes, and same dispersion coeff. ,
kinetic coeff, loads.
U = 300 cfs/2000 ft2 = 0.15 fps = 2.46 mi/day
Using U = 2.46 mi/day, calculations similar to low flow analysis are
performed.
a) Total Nitrogen
C = 1080/(300x5.4) = 0.67 Dig/l
C= 0.67 e2'46x/2= 0.67 e1'33*. x < 0
b) Total Coliform
m = 0.661, m = 1.909, j = -0.559/mi, g = 1.789/mi
LQ = (10 x 1000)/(300 x 1.909) = 17.5 MPN/100 ml
L » 17. S e1>789x, x < 0
.L= 17.5 e-
c) Dissolved Oxygen Deficit
n: a 0.0826, m1 = 1.153, J: = 0.0941/mi, gj = 1.324/mi
n = 0.1322, m = 1.236, J = -0.1451/mi, g = 1.375/mi
6480
300x5.4xl.153
-0.0941x7.13 1.153 -0.1451x7.13,
e * IT236 e 5
Dc = 5.783 (0.1797'J = 1.04 ng-DEF/1
D = 5.783 (e1>324x- 0.933 e1-375x), x <_ 0
D = S.783 (e-"-0941x . „_„, ^0
Comparative plots of resulting concentrations for both flow conditions
appear on Figure 5-16.
-------
Freshwater flows of 50 cfs and 300 cfs are used for the low flow and
summer average condition and these are assumed constant throughout the
estuary. The STP effluent flow of 10 cfs is not included in these
values and appropriate sensitivity runs could be made to assess its
effect. An average tidal velocity of 0.6 knots is used, a value generally
obtainable from annually published NOAA Tidal Current Tables(9). The
2
dispersion coefficient (E) is assumed to be 2 mi /day, a value generally
representative of the more upstream portion of an estuary. Kinetic
rates for the wastes are extracted from Table 5-12.
In the low flow analysis, the maximum total nitrogen concentration is
calculated as 4.0 mg/1 at the point of discharge. With a freshwater
velocity of 0.41 mi/day and an estuary number of 23.8, a maximum total
coliform concentration of 20 MPN/100 ml results at the discharge location,
indicating minimal impact from this source. Using the average tidal
velocity of 0.6 knots (= 1.0 fps) and the average mean water depth of 10
feet, a reaeration coefficient of 0.4/day is generated. The maximum
dissolved oxygen deficit of 2.28 mg/1 occurs approximately 0.8 miles
downstream of the point of discharge. Similar computations are performed
for the summer average flow condition. The comparative plots between
the two flow conditions, displayed in Figure 5-16, give insight into the
behavior of estuaries. The maximum total nitrogen concentrations of 4.0
and 0.67 mg/1 are in inverse proportion to the flow, as in stream analyses.
On the other hand, the peak total coliform concentrations of 20 and 17.5
MPN/100 ml indicates that the freshwater flow has little effect. The
maximum dissolved oxygen deficit of 2.28 mg/1 for the 50 cfs flow is
reduced to 1.04 mg/1 for the flow of 300 cfs showing some reduction to
increased flow but not in proportion to the flows. In general, for the
more reactive substances, the estuary numbers will be higher (n = 23.8,
coliform; n = 2.974, UOD; n = 0, total nitrogen) and the impact of flow
will be less.
5,.3.3.2 Example of Estuary with Multiple Waste Source
Table 5-18 contains analyses for an estuary with a point source
representative of a secondary municipal STP (Table 2-10 pg. 2-53) and a
5-64
-------
C/l
I
in
Q=50CFS
4-
TOTAL NITROGEN
CONCENTRATION (mg/l)
1 1 1 1 1
-10 0 10 20 30 40
X (MILES)
20-
1
TOTAL COL 1 FORM
CONCENTRATION (MPN/IOOml.)
\
\ I 1 1 1
-10 0 10 20 30 40
X (MILES)
DISSOLVED OXYGEN DEFICIT
CONCENTRATION (mg/ 1)
1 till
-10 0 10 20 30 40
X (MILES)
Q= 300 CFS
4-
2-
TOTAL NITROGEN
CONCENTRATION (mg/l)
i 1 1 1 1
-10 0 10 20 30 40
X (MILES)
CCOLIFORM
MTRATION (MPN/IOO ml.)
1 H I I
-10 0 10 20 30 40
X (MILES)
2-
1-
DISSOLVED OXYGEN DEFICIT
CONCENTRATION (mg/l)
/"--—-______
1 1 1 1 1
-10 0 10 20 30 40
X (MILES)
FIGURE 5-16
CONCENTRATION PROFILES FOR ESTUARY WITH SINGLE POINT SOURCE
-------
(Jl
1
^ > Q *
Non-Point Source (x = 0 at MP 54, a = 2 mi)
100 X 3 X 105/4 , 1.980(x+2) _1.980(x-2) „ „. ,
L 900xl.685xl.980 tc "° ' * -
, 100 x 3 x 105/4 ^-0.505(x+2) ,,-0.505(x-2), ,,.„.,,
L " 900 X 1.685 l° ° ' ' ~ ~
100 x 3 x 105/4 , -0.505(x+2) ,-0.505(x-2), Y s ,
L " 900x1. 685(-0. 505) l° ° ' ' -
L^^ occurs at X: = 2/1.685 = 1.187 mi (Table 5-10)
PS NPS Total PS NPS Total
MP XP Cone. x Cone. Cone. MP X£ Cone. x Cone. Cone.
60-8 0-6 1 1 50 2 48 4 3094 3142
58-6 0 - 4 48 48 49 3 29 5 1867 1896
57 - 5 0 - 3 345 345 48 4 18 6 1127 1145
56-4 0-2 2498 2498 47 S 11 7 680 691
55-3 0-1 6375 6375 46 6 68 410 416
54 - 2 3 0 8677 8680 45 7 49 248 252
53 - 1 18 1 9794 9812 44 8 2 10 149 151
52.81 -0.81 26 1.19 9834* 9860* 42 10 1 12 54 55
52 0 132* 2 8495 8627 40 12 0 14 20 20
51 1 80 3 5126 5206 38 14 0 16 7 7
•Max. Cone.
-------
On
l
EXAMPLE OF ESTUARY
DISSOLVED OXYGEN DEFICIT ANALYSIS SUMMER AVERAGE CONDITION
Q = 300 cfs, U = 0.9S4 mi/day, E = 2 mi2/ day, K: = Kf = 0.25/day
K2 = Ka'= 4 ft/day T 10 ft = 0.4/day
me 0 51fi m - 1 7">n a - 0 fi77/mi -i =0 Iftd'Wnn
n2 = 0.826, m2 = 2.075, S2 = 0.756/mi, J2 = -0.264/mi
From Table 5-11, DO DEF are calculated as follows:
Point Source
0.25 17280 °'677xp 1.7SO °'756 *p
0.4-0.25 300x5.4xl.750 l 2.075 J>Ap_u
„ _ 0.25 . 17280 . -0.1845*!, 1>75() -0.264x ^
D ~ 0.4-0.25 300x5.4xl.750 (C 2.075C J'xpi°
V- Inf1'750 i"2-075! • f°-984 r- Q7S 1 7Soil -. ' 37 mi
" ln(2.075 1-1. 7503 ' C 2x2 C<"075 1-7SOJ' n 2'37 **-
c
Non-Point Source
„ 0.25 2160 ,e0.677(xt21.e0.677(x-21.
0.4-0.25 300x5.4 l- 1.750 X 0.677
0.7S6(x+2) Q.765(x-21
. ? "e •) x c ,,•>
2.075 X 0.756 J ' — "
- 0.2S 2160 e-0.1845(x+2).1 e0.677(x-2)
0.4-0.25 300x5.4 U1.750C-0.184S3 1.750x0.677 '
-0.264CX+2) 0.7S6(x-2)
f " "\"\ *<.*<.*
L2.075(-0.264) 2.075x0.756 >>' "--
„ 0.2S 2160 e-0.1845(x+2).e-0.184S(x-2)
0.4-0.25 300x5.4 l 1.750C-0.1S45)
-0.264(x+2) -0.264(x-2)
e ~e .^ K;,-?
2.075x0.756 J >X-
Location of max. deficit (Table 5-_)
2x2(-0.184S) . 2x2(-0.264) ,
- = " ":r+n nifi
1.750 2.075 + U-Ulb
TABLE 5-18
(Continued)
r WITH MULTIPLE WASTE SOURCES
Since s > 0, Xc > a = 2 and xc satisfies (Table 5-9)
-0.1845(x +2) -0.1845(x -2) -0.264(x +2) -0.264(X -2)
e -e e c -e c
1.750 " 2.075
from which X =2.66 miles.
c
PS NPS Total PS NPS Total
MP xp Cone x Cone. Cone HP xp Cone. x Cone Cone.
60 -8 0.02 -6 0,05 0.07 49.63 2.37 1.98* 4.37 0.90 2.88
58 -6 0.08 -4 0.15 0.23 49 3 1.96 S 0.87 2.83
56 -4 0.26 -2 0.40 0.66 48 4 1.88 6 0.80 2.68
55 -3 0.45 -1 0.58 1.03 46 6 1.60 8 0.64 2.24
' 54 -2 0.73 0 0.75 1.48 44 8 1.29 10 0.50 1.79
S3 -1 1.59 2 0.95 2.54 37 15 0.47 17 0.17 0.64
51.34 0.66 1.80 2.66 0.96* 2.76 32 20 0.21 22 0.01 0.22
50 2 1.97 4 0.92 2.89*
*Max. Cone.
Dissolved Oxygen Deficit - Low Flow
Q B 50 cfs, U = 0.164 mi/day,
m: a 18.59, m1 = 8.681, gj = 0.3969/mi, Jk = -0.3149/mi
n, s 29.74, m, B 10.953, g, = 0.4901/mi, j, a 0.4081/mi
Point Source: x « 0,2861 miles, D =2.56 rag/1
c c
Non-point Source: None
-------
distributed intermittent source with characteristics similar to a separate
sewer system (Table 2-11,pg. 2-58). Total coliform concentrations are
calculated for a summer storm condition typical of a major storm system
with a duration of several days. Dissolved oxygen deficits are calculated
for summer average and low flow conditions. Estimates of the non-point
flows are consonant with the municipal area served and detailed calculation
of these values would be performed using methods in Chapter 3.
Using the equations in Table 5-11 for both point and non-point sources,
tabular solutions for given estuarine milepoints are set up. The point
source solutions are generated for the coordinate system x , with origin
at Milepoint 52, and the non-point concentrations use an x - abscissa
with origin at Milepoint 54. Following the detailed equations and
tabular solutions for both total coliform and dissolved oxygen deficit,
plots of the concentration profiles are presented for the combined
impact of both sources and the effect of the point source alone in
Figure 5-17.
The profiles for total coliform indicate that the separate sewer system
is causing over 5,000 MPN/100 ml in the estuary from Milepoint 50 to
Milepoint 56 whereas the peak concentration due to the STP is approximately
130 MPN/100 ml. The results for the intermittent separate sewer discharge
are reasonably accurate since the bacteria are highly reactive and only
require one to several days to approach the equilibrium (steady state)
concentration. Thus, it could be concluded that the sewer system is a
major source of bacterial contamination and further efforts should be
devoted to quantifying its impact on a statistical basis.
The peak dissolved oxygen deficit occurs between Milepoint 49 and
Milepoint 50 for the summer average condition. The STP contributes 2.0
mg/1 and the separate sewer 0.9 mg/1 to the total deficit of 2.9 mg/1.
The deficit of 0.9 mg/1 from the intermittent separate sewer discharges
may be a significant overestimation since the more slowly reactive UOD
may require several days to several weeks to attain a steady state
concentration. In the low flow analysis without separate sewer discharges,
the STP causes a peak deficit of 2.6 mg/1. If one assumes an estuarine
chloride concentration of 7500 mg/1 ( 30% seawater) and a water temperature
5-68
-------
SEPERATE
SEWERS
L
7777
MUNICIPAL S.T.P.
K///////////J
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ipoo
100
56
52
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48 44 40
MILE POINT
36
1
32
POINT AND INTERMITTENT SOURCES
SUMMER STORM CONDITIONS
0= 900 CFS
I I
60 56 52 48 44
MILE POINT
40
36
en
E
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SUMMER AVERAGE CONDITIONS
0= 300 CFS
POINT AND INTERMITTENT SOURCES
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6O
56
52
48 44 40
MILE POINT
36
32
FIGURE 5-17
CONCENTRATION PROFILES-ESTUARY WITH MULTIPLE SOURCES
5-69
-------
of 25 C, the dissolved oxygen saturation concentration is 7.7 rag/1
(Figure 2-19(b)). Therefore, minimum dissolved oxygen concentrations of
4.6 mg/1 and 5.1 mg/1 occur in the estuary for summer average and low
flow conditions respectively. Depending on the water use and
classification, water quality standards may or may not be contravened by
these results. In any case, the dominant cause of the deficit is the
continuous STP discharge 'and solution of any dissolved oxygen problem
would emphasize alternatives involving the STP.
5.3.4 Methods For Estimating Water Quality Variability in Estuaries
The steady state water quality analysis for estuaries described in the
previous sections is appropriate for estimating receiving water responses
for annual average loads, or as shown in Section 5.3.3, for water quality
analyses of average conditions during critical average or high flow
(storm) periods. Another method of evaluating variability in receiving
water response is briefly presented in this section.
In cases where the steady state response can be developed using the
equations in Table 5-11 or a numerical water quality model, it is often
useful to obtain an estimate of the random (at least for purposes of
this discussion) variability of that response. Consider the observed
and computed water quality profiles shown in Figure 5-18. In this case,
the computed response, which adequately represents the mean observed
water quality data, is shown to be within the water quality standard.
However, the observed variability in dissolved oxygen indicates that
frequent measurements are below the standard. ,An important question is:
if mean water quality can be maintained above a standard, as in Figure .
5-18, what is the estimated frequency with which the standard will be
violated due to random variations about the mean?
The task facing the 208 planner is often one of evaluating the frequency
with which water quality objectives will be violated under a wide range
of control options, including the 'no action' alternative, Steady state
mean responses are generally limited in their interpretation within this
context. However, a simple method is presented in this section for
5-70
-------
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Ct'8.0mg/l
LEGEND:
I
OBSERVED'HEAN
AND RANGE
• COMPUTED MEAN
I
3 4
DISTANCE-MILES
FIGURE 5-18
EXAMPLE SUMMARY OF DISSOLVED OXYGEN DATA
SHOWING VARIABILITY
5-71
-------
employing steady state model results in concert with water quality data
to estimate the frequency of compliance with water quality objectives.
5.3.4.1 Method of Analysis
In many receiving waters the variability of a water quality indicator
increases as the stress on the area increases. The greatest variability
around the mean dissolved oxygen response in a stream is expected to
occur in the region of the maximum deficit(10). Similar responses are
observed in estuaries(11). However, the analytical techniques to evaluate
such responses are not straightforward for estuaries.
An empirical approach to analyzing the problem is suggested in Figure 5-
19(a) which presents a cross plot of the long term mean and the standard
deviation of dissolved oxygen deficit concentrations for a number of
sampling stations in South San Francisco Bay. The probability density
function at each station must be known and must be the same at all
stations. The display indicates a trend in this study area toward
increasing variability in deficit concentration in areas of large mean
dissolved oxygen deficit concentrations. In this particular case the
statistics were shown to be associated with normally distributed deficits
at each station.
Figure 5-20 displays a mean computed dissolved oxygen concentration
profile for the study area. Also shown in the figure is the estimated
lower 90 percentile dissolved oxygen concentration computed in the
following manner. ^
a = 0.4 + .25 Def (from Figure 5-19)
Def = 90 percentile deficit = Def + 1.27 (0.4 + .25 (Def)) (5-7)
where:
Def = mean computed dissolved oxygen deficit concentration =
(Cs - DO)
1.27 = 90% ordinate of the normal cumulative probability curve, g
C = Dissolved oxygen saturation
5-72
-------
(A)
(B)
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SOUTH SAN FRANCISCO BAY
O WET WEATHER DATA
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MEAN DEFICIT, D (mg/l)
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OSWEGO Rl VER, N. Y.
WET WEATHER DATA
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MEAN DEFICIT, D (mg/l )
FIGURE 5-19
MEAN VS. STANDARD DEVIATION'OF, DISSOLVED OXYGEN DEFICIT CONCENTRATION
-------
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MAIN BAY TRANSECT
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MEAN DISSOLVED OXYGEN
;•• ;,. ; (COMPUTED)
••• •"•' LOWER 9O PERCENTILE
DISSOLVED OXYGEN(COMPUTED)
.———LOWER 90 PERCENTILE
STANDARD
-•—MINIMUM DISSOLVED OXYGEN
STANDARD: S.Omg/1
I I I I I 1
1
2 3 4 5 6 7 8 9 10 II 12 13
MILES FROM ARTESIAN SLOUGH ON MAIN TRANSECT
14
15
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9.
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SEGMENT
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MILES FROM SJ/SC OUTFALL
I 234567
MILES FROM GAGING STATION
FIGURE 5-20
EXAMPLE OF ESTIMATING VARIABILITY
AROUND STEADY STATE MEAN WATER QUALITY
5-74
-------
DO = mean computed dissolved oxygen concentration
De£_n = 90 percentile deficit concentration
For example, if the mean dissolved oxygen deficit concentration at a
location in the South Bay is computed to be 1.2 mg/1 and saturation is
7.5 mg/1, the lower 90 percentile dissolved oxygen concentration can be
estimated as:
Def = 1.2 mg/1
Defgo= 1.2 + 1.27 • (0.4 + .25(1.2)) = 2.09 mg/1
D09Q = Cs - Defgo = 7.5 - 2.09 = 5.41 mg/1
where:
D0go = 90 percentile dissolved oxygen concentration.
Conversely, if a relevant planning question is to respond to the frequency
with which the 5.0 mg/1 standard is expected to be violated in the above
example, Equation 5-7 can be solved for the ordinate, g, on the normal
cumulative probability curve. The formula for this computation is:
DO - (C - Def)
o - E §
0.4 + 0.25 Def
_ 5.0 - (7.5 - 1.2) _ -1.5 _
3 " .4 + .25(1.2) " 0.7 ~ "1'8b
Cumulative normal distribution tables, found in most statistical texts or
(17) can be used to determine that 1.86 corresponds to a 97% event.
Therefore, 3% of the dissolved oxygen concentrations at that location
might fall below the 5.0 mg/1 standard due to random background factors
not included in the modeling analysis.
Application of this method need not be limited to dissolved oxygen
concentration alone. Relationships similar to those shown in Figure 5-
19 can be used to develop background variabilities in specific water
quality constituents for purposes of making probablistic statements
using steady state water quality model results. Such methods are
particularly useful in estimating the frequency with which standards
might be violated in streams or estuaries. The 208 planner is cautioned
5-75
-------
to pay particular attention to the frequency distribution of the
concentrations (i.e., normal, lognormal, gamma) in applying this analysis
and also to the sample size used to generate each point in a figure such
as Figure 5-19. A sample size greater than 10 observations at each
station should be adequate to indicate reliable trends in the data.
5.4 Coastal Areas
The disposal of wastewaters in open water bodies is frequently an
attractive wastewater discharge alternative because of the large quantities
of available dilution water. The discharge is accomplished using an
underwater outfall conveyance line to the disposal site. Good engineering
practice usually necessitates a multiport diffuser structure at the
terminus of the outfall to facilitate dilution-mixing of the wastewater
in the overlying water column. Diffuser design is expensive and requires
a comprehensive analysis of many water quality constituents. • Caution
must be exercised in final design considerations to justify such a
structure. Analyses of this type consider such factors as: BOD-
dissolved oxygen, nutrients and biostimulation, bioinhibition, sanitary
water quality, and aesthetic concerns.
Analysis of water quality in coastal areas and large open water bodies
is often viewed as a multi-dimensional problem, the principal features
of which are:
1. Plume rise and initial dilution
2. Two dimensional spreading of diluted waste constituents within
a mixing zone
3. Advective transport of dilute wastewater mixtures toward
shorelines and other vulnerable areas.
The analysis proceeds through separate analysis steps which focus on
these three scales of problems (at least until a no effect level of the
pertinent water quality constituents is reached). That is, if the
analysis indicates that the concentration of pertinent water quality
constituents meets objective levels after initial dilution, a conservative
estimate of water quality in the mixing zone or at shoreline areas is
that it also meets the objective levels.
5-76
-------
Section 5.4 presents first approximation analysis techniques and guidelines
which are appropriate for analyzing this class of wastewater discharges.
The methods can be applied using data collected in the study area in
combination with estimated model coefficients which find rather wide
application in engineering practice. The methods are also applicable to
study areas other than coastal areas. For example open water bodies
such as large lakes or large estuaries can be analysed using methods
presented here. Guidelines for these analyses are presented with each
analysis description. Dispersion coefficients in large lakes can
be found in Section 5.5.3.3.
The analysis methods for coastal areas are only for preliminary assessments
of water quality impacts. While the methodologies are useful in making
level 1 decisions they can and in many cases should be supplemented by
more detailed numerical modeling techniques. The 208 planner should
exercise engineering judgement in deciding when an analysis indicates
the existence of water quality problems which warrant detailed analysis
either because of the magnitude of the water quality problem or the
costs to implement controls suggested by the preliminary analysis.
Guidance in this regard is presented in Section 5.6.
5.4.1 Initial Dilution
Initial dilution is the term applied to the ratio of seawater to wastewater
mixed by port discharge of effluent from a diffuser manifold into seawater.
Initial dilution takes place during the rise of the effluent plume
toward the water surface or to some intermediate trapping level.
Momentum of the discharging jet together with the buoyancy associated
with density and temperature differences produce shear stresses resulting
in boundary turbulence as the plume rises toward the surface. This
turbulence facilitates seawater entrainment and dilution of the effluent.
The relationships between buoyancy, shear, and dilution are complex and
are dependent to a large degree on the ambient density structure in the
receiving water. Existence of a moderate salinity gradient or a moderate
thermocline may preclude the effluent plume reaching the water surface.
This specific case will not be discussed in this manual. However the
5-77
-------
user is referred to reference (12) for a detailed discussion of nomographic
methods for analysing the stratified ocean case. In general the effect
of a vertical density gradient is to reduce initial dilution and also
the height of rise of the effluent plume. Some guidance in evaluating
this case is presented later in this section.
The assumption of a uniform density structure implies vertical uniformity
in the receiving water in so far as temperature and salinity are concerned.
In this regard, Rawn, Bowerman, and Brooks (13) using dimensional analysis
reevaluated the earlier work of Rawn and Palmer (14), for hydraulic
model discharges of submerged jets. The result is an empirical correlation
between observed initial dilutions and dimensionless hydraulic parameters
which are appropriate to full scale design. Short term dilution
varies as a function of distance along the centerline of the effluent
plume.
Figure 5-21 schematically shows the effluent plume resulting from a
single port discharge as it rises toward the water surface in a stratified
and non-stratified environment. Assuming no stratification in the water
mass receiving the effluent discharge, S , the initial dilution at the
center of the surfaced plume, is considered a function of five independent
variables: y is the total depth from center of outlet to the surface;
D is the initial diameter of jet (approximated by the port diameter); V
is the jet velocity; g' is the apparent acceleration due to gravity; and
Y is the kinematic viscosity of the sewage. J
g' may be expressed as:
by balancing of forces acting on a buoyed body. In this equation s is
the specific gravity of the wastewater, As the difference in specific
gravity of seawater and wastewater and g the gravitional constant.
It is then possible, to express S as a function of three independent
dimensionless parameters:
5-78
-------
CENTERLINE INITIAL DILUTION
CENTERLINE INITIAL DILUTION ,
Cn
I
MAXIMUM
HEIGHT
OF RISE TRAPPING
LEVEL
BUOYANT PLUME RISE IN A MILDLY
STRATIFIED WATER COLUMN
BUOYANT PLUME RISE IN A HIGHLY
STRATIFIED WATER COLUMN
FIGURE 5-21
BUOYANT PLUME CHARACTERISTICS IN STRATIFIED AND
NON-STRATIFIED ENVIRONMENT
-------
where:
The Froude number, F = ———— and the Reynolds number, R = —.
The magnitude of the Froude number reflects the path of jet discharge
and plume rise as influenced by gravity and by density differences
between seawater and sewage. The Reynolds number is indicative of the
effect of inertia and viscosity as a measure of turbulence. Several
investigators (13, 15) have presented evidence that, for ranges of
turbulent flow, the Reynolds number has little influence on the initial
dilution. Apparently, once significant turbulent flow is developed,
other hydrodynamic forces are of more consequence to dilution.
Eliminating R as a factor once turbulent flow has developed reduces
Equation (5-9)' to:
Y •
SQ = f(-£, F) (5-10)
An illustration of the relationship implied in iequation(S-lO) is presented
graphically with smooth curves in Figure 5-22. This diagram indicates
that for a given Froude number, the initial dilution is directly related
to the depth of water above the discharging port and inversely related
to the diameter of the port. The greater the depth of receiving water
and the smaller the port, the greater is the initial dilution. These
curves, based on observed initial dilution data, agree reasonably with
other theoretical developments, and, with a minor modification (empirical)
consisting of multiplication of S by 1.15 to account for a zone of flow
establishment, are applicable to field conditions. With the above
proviso, the curves indicate the minimum initial surface dilution expected
from a single round buoyant jet for various conditions of submergence,
port diameter, port flow, and density difference.
As an example, assume that the required initial dilution is 50 to 1
(50:1). The question is what water depth is required to achieve this
5-80
-------
Q
<£.
UJ
5
120
DO
80
60
50
40
30
20
o.
UJ
Q
10
8
6
J I
5 6 8 10 2O
FROUDE NUMBER F = ——
30 40
REFERENCE: AFTER RAWN, BOWERMAN AND BROOKS
PROC. SED. ASCE, VOL. 86, NO SA Z, I9GO
FIGURE 5-22
INITIAL DILUTION FOR SUBMERGED HORIZONTAL JET DISCHARGE
5-81
-------
objective using a 500 foot diffuser consisting of 40 three inch ports.
The design flow is 15 MGD.
An assumption regarding the flow distribution through the ports is
required first. A good engineering diffuser design normally distributes
the flow uniformly along the outfall. Therefore, the port discharge can
be approximated by:
The port area is : A = (f^)2 j~ 0.049 ft2;
The density of seawater in coastal areas is normally between 1.020 and
1.040 and depends upon nearness to major freshwater discharges from
rivers and approaches 1.000 from fresh water areas at the upstream end ,
of tidal rivers. Reference (16) presents methods for computing seawater
density from salinity and temperature data. For purposes of the present
example, the density of sewater is selected as 1.025, a typical value in
many coastal areas. The density of the effluent can normally be taken as
1.00 unless data indicates significant concentrations of total dissolved
solids (greater than 1000 ppm) .
The Froude number, F, is therefore computed as:
x /32.2 x 1 ' ^l^'
F - 11.83 x 32.2 x ' ' x .25 = 26.4
Figure 5-22 yields a required Y/D ratio of 70 to accomplish the required
initial dilution. Therefore, the diffuser must be located in 18 feet of
water. At low water slack:
^ = 70 = ^25-; Y = 17.5 feet '
If the outfall discharge rate or effluent quality characteristics are
expected to vary between wet and dry weather conditions as might be
expected if the treatment plant load is from a combined sewer system,
5-82
-------
the analysis should be performed for wet weather conditions. In this
case the anal/sis would be repeated for higher flow conditions (i.e., Q
= 40 MGD) and the required initial dilution would reflect wet weather
effluent quality.
In cases where a non-uniform denisty gradient exists, the foregoing
analysis is not supported by experimental data. In those cases the 208
planner can develop an estimate of the range of initial dilutions to be
expected in one of two ways, both of which require some experimental
data on stable vertical density gradients in the study area. The first
method is a very simplified analysis, but one which is generally acceptable
for preliminary assessment purposes. Assume a maximum height of rise of
the effluent plume by inspecting the vertical density gradients in the
study area. The density gradient shown in Figure 5-21 (b) is typical of
many coastal areas. That is there is a sharp break in the density
structure at an intermediate depth. This depth can be used in Figure 5-
22 to estimate the maximum initial dilution. For most situations this
estimate should not be in error by more than 20 - 30%.
An alternate method for performing more reliable estimates of initial
dilution in uniformly stratified coastal areas is presented in Reference
(12). This solution to a complex set of experimentally derived
relationships yields estimates of the expected height of rise and the
expected initial dilution. The reference presents detailed examples of
the calculation procedure.
5.4.2 Analysis of Far Field Effects
Ocean disposal of treated effluent necessitates consideration of several
factors affecting the final concentrations of contaminants in the nearshore
ocean environment. These include physical, chemical, and biological
factors, each of which contributes to the total dilution achieved by
outfall disposal of wastewaters.
Physical factors include the dilution of effluent constituents with
surrounding seawater and dispersion, which spreads the effluent field.
In the specific case of bacteria, aftergrowth phenomenon and the natural
die-away and predation are additional factors effecting total dilution.
5-83
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The emphasis in Section 5.4.2 is on analyzing the transport and
distribution of coliform bacteria and the consequent impacts on sanitary
water quality. The analysis techniques are however appropriate for
other water quality indicators such as suspended solids, acute and
chronic toxicants, total nutrients and, with some modifications, color.
Bacterial levels are presently the major criteria for evaluating the
acceptability of recreational bathing waters and areas of shellfish
culture. Therefore, a prime concern in the design of ocean outfall and
diffuser systems is the maintenance of coliform objectives at beaches
and shellfish beds. Four basic factors are considered in forecasting
coliform levels from the discharge of treated wastewater effluent in the
marine environment: a) initial concentration in the treated effluent,
b) initial plume dilution, c) physical dilution, and d) bacterial
aftergrowth and dieoff. Initial concentrations are normally developed
from treatment plant effluent records and from land side simulation
techniques similar to those presented in Chapter 3. Initial dilution
was treated in the previous section of this chapter.
5.4.2.1 Physical Dilution
After the initial dilution of the effluent field is completed, tidal
motion and other larger scale phenomenon such as wind and ocean currents
spread the field away from the diffuser zone. Longitudinal and vertical
mixing are generally assumed to be negligible. Therefore, lateral
dispersion is the principal factor responsible for far field dilution
known as physical dilution.
Figure 5-23 exhibits an idealized surface effluent field as it is
translated away from a diffuser device by an ocean current. The diagram
indicates the concentration.distribution of material in the effluent
field as it moves along the longitudinal axis, x,1 from the diffuser
device at current velocity, U. The initial concentration C , in a field
width, b, is almost uniform in the immediate vicinity of the diffuser
structure. However, as the field is translated and is dispersed along
the lateral axis, concentration gradients develop. The maximum
concentration along the centerline of the effluent field decreases and
5-84
-------
OO
Cn
I 1
I S9 |
4 t :•-
^ir
—
g .^a*?*?*^. W-x^
INITIAL DILUTION
PHYSICAL DILUTION
FIGURE 5-23
DIAGRAM OF INITIAL AND PHYSICAL DILUTION
-------
is gradually reduced toward the limits of the effluent field. The
concentration of any effluent material is related therefore, to
longitudinal distance, x, and the lateral spread, y, of the effluent
field.
A mathematical representation of this phenomenon predicts the short-term
steady state concentration of an effluent field produced by discharge
from a multiport diffuser.
The partial differential equation governing this phenomenon is discussed
by Brooks (17). The equation is solved for the case of variable dispersion
coefficients. It is assumed that lateral dispersion, expressed by the
coefficient E , varies with distance along the longitudinal axis of the
effluent field as a function of the field width. Based on empirical
evidence and theoretical development, oceanic dispersion coefficients
have been related to scale by the following expression:
E = eL4/3 (5-11)
where:
E = the lateral dispersion coefficient
L = the width of the effluent field,
e = an empirical constant.
A value of e = 0.01 for cgs units is suitable for surface effluent
fields. No information is presently available in the literature for the
submerged field case; that is, the case in which the effluent plume
remains submerged below the density gradients shown in Figure 5-21(b).
By applying the pertinent boundary conditions, and assuming that the
lateral dispersion coefficient varies with scale according to equation
(5-11) where L is taken as the projected width of the effluent field
normal to the current, the concentration of an effluent constituent at
various distances from the outfall diffuser is:
C = C erf
o
3/2
8E x
,
1/2
(5-12)
u
5-86
-------
in which:
C = concentration along x-axis of the effluent field
direction of current
C = concentration at x = 0.
o
x = distance along x-axis of effluent field
U = current velocity along the x-axis
b = initial width of effluent field above the diffuser and
normal to the current
E = lateral dispersion coefficient at x = ^ as defined by
e'quation (5-11) where L = b
2 Z v2
erf(z)= error function ^j= / e dv
>"-\ *
Once an outfall and diffuser system has been designed on a preliminary
basis from initial dilution considerations, equation (5-12) is normally
used to determine the pattern and concentration of the resultant effluent
field and physical dilution. The lateral dispersion coefficient is
assigned on the basis of diffuser orientation, diffuser length and
initial field width. Current velocity information may be obtained from
Tide and Current Tables and Tidal Current Charts prepared by the National
Oceanographic and Atmospheric Administration. This information can be
obtained by writing to: National Ocean Survey, Rockville, Maryland
20852 or a local sales office (normally located at marinas or marine
supply sales centers).
-• 5.4.2.2 Biological Factors
Discussion to this point has been limited to those physical factors
which affect dilution and dispersion of the effluent. All effluent
constituents are subject to physical dilution phenomena. However,
certain constituents, notably organics and bacteria are subject to
reactions which result in a concentration decay.
Bacterial populations undergo growth and death in a natural environment.
To incorporate this phenomenon into equation (5-12), a first-order
reaction rate, K, is assumed. The resulting equation is:
5-87
-------
—
-kx
C e U erf
o
3/2
8E x
n + ° i3 i
I1 + 9J - J-
U b
1/2
(5-13)
where t is the reaction time, and may be expressed as x/U.
Currently available information on the behavior of bacteria in the
marine environment suggests the possibility of an aftergrowth phenomena
after discharge into a receiving water. The aftergrowth is followed by
a rapid die-away of"the bacteria. Sequential aftergrowth and die-away
have been postulated'"as first-order reactions and are normally included
in bacterial analysis using equation 5-13. There are two methods of
treating aftergrowth phenomenon in equation(5-13). The first is to apply ^
an aftergrowth factor to the initial concentration, C . Thus: C.. = A C ,
where A is the aftergrowth factor expressed as a multiple of the initial
concentration in the effluent field. The magnitude of the aftergrowth
is strongly dependent upon water temperature and incident ultraviolet
solar radiation. Typically aftergrowth factors range between 1.0 and
5.0. The lower end of the range is indicative of warm waters in sunny
conditions such as might occur in the southern portions of the United
States. The higher aftergrowth factors are normal in areas where the
sunlight intensity is low or where water clarity is poor.
A second method of estimating,aftergrowth is through a modification of
equation[5-13)to include both the die-away and aftergrowth processes.
The resulting equation is similar to equation(5-13)and reflects a
separation of the overall reaction rate, K, into its two components: 0
KI, a die-away coefficient, and K2, an aftergrowth coeficient.
C = C e
o
erf
3/2
8E x 3
1/2
(5-14)
Where K., is treated as a constant in time and K2 is a positive aftergrowth
rate in the time interval t = 0 to t = T.. T is defined as the time
required to realize the aftergrowth fraction A as defined above. Thus:
5-88
-------
A = e 2 A; TA = . (5_15)
An aftergrowth factor of 3 in 12 hours is typical of marine systems.
InA 74
Therefore: K = —• = f^- x In (3) = 2.2 per day.
IA 1^
Knowledge of the physical and geometric parameters of the diffuser and.
oceanic systems, along with estimates of the appropriate reaction rates,
allows the calculation of the probable concentration of substances at
any distance from the point of discharge (for various current velocities
and directions) on a short-term basis.
5.4.2.3 Application of Analysis Methods
An example of the methods for evaluating water quality at locations
remote from the diffuser are demonstrated in this section. A diffuser
with characteristics described in Section 5.4.1 is used. In the example,
only sanitary (bacterial) water quality is evaluated. Other parameters
can be evaluated in a similar manner. The basic data is:
Required initial dilution(S. ) = 60:1
Length of Diffuser (1) = 500 feet
Discharge Depth = 18 feet
Mean Current Velocity (U) = 50 fpm (0.83 fps)
Oceanic Diffusion (E ) = 0.01 L ' (cgs units)
4
Effluent coliform cone. (C ) =10 MPN/100 ml
e i
Coliform Die-away rate (K ) = 1.0 day
*• ' i
Coliform Aftergrowth rate (K ) = 2.2 day (12 hours).
The maximum concentration of coliform organisms at a shellfish harvesting
location 10,000 feet away from the diffuser is estimated as follows:
CQ = Ce/So = = 170 MPN/100 ml
2
E = .01 (500 ft x 30.5 cm/ft)4/3 = 3782 — = 4.1
O SGC
t = 10,000/50 = 200 Min = .14 days
5-89
-------
Therefore, aftergrowth is appropriate for the entire spatial interval.
Co (167) -1-0(0.14)e2.2(0.14)
5/2
(1 + 8 (4.1) (10, OOP) 3
0.83(500)2
1/2
C = 197 erf(0.306)
The error function is evaluated using standard error function tables (18)
to be 0.893, and:
C = 176 MPN/100 ml
Therefore, the coliform concentration within the shellfish area is
expected to be 176 MPN/100 ml under the assumed conditions. Conditions
at other current velocities can be similarly computed and compared to
water quality standards for sanitary water quality for shellfishing
within the study area. The computed concentration, 176 MPN/100 ml at
mean current velocities normally indicates a high probability of a
problem in a shellfishing area. Local standards should be consulted
before evaluating the problem further.
5.5 Lakes and Impoundments
Information presented in this section is taken in large part from reference
(19 ). Lakes and impoundments are characterized by physical features which
result in a special class of water quality problems. The relatively
long detention times in these systems permit relatively slow reaction
processes to proceed to completion; response times to changes in loadings
are longer than for river or estuary systems; and transport characteristics
in three-dimensions are frequently required to adequately analyse the
system. The procedures and methods presented in this section are designed
to permit the 208 planner to analyse lake systems in a preliminary
assessment framework. The methods focus on major problems and yield
fundamental relationships between loads and water quality which must be
interpreted prudently. The planner is cautioned to exercise critical
judgement in using Section 5.5, and utilize qualified persons and
5-90
-------
consultants in analysing problem frameworks which are beyond the scope
of these analyses.
Lake systems have historically been analysed in numerous frameworks,
from simple empirical analysis methods to sophisticated numerical
models of transport and kinetic reactions. This section of the manual
deals with lake water quality in terms of the simpler methods and
relatively straight forward numerical methods which can be performed
with an electronic calculator. Stratification in lakes is described in
terms of a dimensionless parameter so that first cut assessments of the
vertical dimension of water quality problems can be determined. Empirical
methods for assessing nutrient loadings are then reviewed to place
eutrophication problems in perspective. Methods suggested by Vollenweider
and Dillon (20>21) are employed for this purpose. Finally, closed-form
solutions to equations for analysing a wide spectrum of special water
quality problem types are presented and demonstrated. Where appropriate,
assumptions and limitations are clearly spelled out.
5.5.1 Stratification in Lakes and Impoundments
A method for classifying lakes as deep stratified systems, weakly
stratified, or vertically mixed is fundamental to defining the vertical
dimension of water quality problems in lakes. The classification system
is based on the ratio of the inflow volume to the storage volume in the
impoundment. Three classes are defined as follows:
a. Deep stratified lake (low flow to volume ratio). Reservoirs
in this class are large and have detention times greater than
one year. They are characterized by periods of strong vertical
stratification.
b. Weakly stratified lakes (medium flow to volume ratio). Large
lakes with detention times in the order of four months to a
year are normally in this class.
c. Vertically mixed (large flow to volume ratio). This class
generally includes run-of-the-river impoundments with detention
times less than four months. Vertical temperature gradients
5-9!
-------
are not present; however, longitudinal temperature variations
may exist.
Determination of the impoundment classification is made by computing its
densimetric Froude number (F ). This number is the ratio of the inertial
force of the horizontal flow to the gravitational forces within the
impoundment. Consequently, it is a measure of the ability of the
horizontal flow to alter the internal density structure of the reservoir
from its static equilibrium condition. The densimetric Froude number is
given by:
F = I& _£ . (5-16']
D DV ge L:> i(Dj
where:
Fn = densimetric Frounde number
L = reservoir length (ft)
D = mean reservoir depth (ft)
Q = flow through the reservoir (cfs)
V = reservoir volume (ft )
2
g = gravitational constant (ft/sec )
_2
e = average normalized vertical density gradient (5.25 x 10
Ibs/ft3-ft)
p = reference density.
Substituting values for the constants g, p, and e, the equation simplifies
to:
FD = 320 L $ (5-17)
The use of this equation is demonstrated in Table 5-19. In a deep lake
where the isotherm is horizontal, the inertia of the longitudinal flow
will be insufficient to disturb the overall gravitational (or density)
static equilibrium state of the lake. Local disturbances may occur at
points near the tributary inflow and the lake outlet. Thus, the FD for
such an impoundment is small. For the vertically mixed reservoir, the
inertia of the inflow is sufficient to completely upset the density
5-92
-------
structure, leaving the impoundment non-stratified. F for reservoirs of
this class is large. Between these .two extremes lies the "gray area"
which includes the weakly-stratified reservoirs. Here the longitudinal
inflow has enough inertia to disrupt the gravitational static equilibrium
configuration but is not sufficient to completely mix the reservoir.
Theoretical and experimental work in stratified flow indicates that flow
separation or stratification occurs in systems having F values in the
order of 1/ir or 0.32. For F values less than 0.32, the water flow will
be longitudinal or stratified, while for F values greater than 0.32,
the water column is more mixed in the vertical direction. A general
rule to follow is:
F values» 0.32 - completely mixed lake
F values« 0.32 - deep, stratified lake
FD values 2. Q.32 - weakly stratified lake.
Table 5-19 presents the Froude number for a selected group of reservoirs
and demonstrates the classification system presented above. The value
of the specific Froude number which would distinguish the transition
from one classification to another has not yet been clearly determined.
5.5.2 Eutrophication Assessment Methods
Assessments of the eutrophication potential in an impoundment is of
concern because of the long detention times of these systems.
Eutrophication is very complex and not easily adapted to simplified
analysis techniques. Various approaches have been used to empirically
evaluate the conditions in impoundments. The most widely used one is
discussed here. Several other techniques are also available. The
applicability of these techniques to a site specific study area must be
determined on an individual impoundment basis. The manual user selecting
such a method should become familiar with the various assumptions involved
in its development and determine if these assumptions are valid for the
impoundment under study.
5-93
-------
TABLE 5-19
CALCULATION OF FROUDE NUMBER FD FOR LAKE CLASSIFICATION
On
r
Reservoir
Lake Roosevelt (Wash)
Priest Rapids (Wash)
Wells (Wash)
Detroit (Wash)
Hungry Horse (Wash)
Lake LBJ (Tx)
Lake Livingston (Tx)
Length
(feet)
2.0 x 105
2.9 x 104
4.6 x 104
1.5 x 104
4.7 x 104
34 x 103
3.8 x 104
Average
Depth
(feet)
70
18
26
56
70
7
6.5
Discharge to
Volume Ratio
(sec'1)
5.0 x 10~7
4.6 x 10"6
6.7 x 10~6
3.5 x 10"8
1.2 x 10~8
3.3 x 10~7
1.0 x 10"7
Froude
Number
FD
0.46
2.4
3.8
0.003
0.0026
0.51
0.51
Class
Weakly Stratified
Vertically Mixed
Vertically Mixed
Deep
Deep
Weakly Stratified
Weakly Stratified
-------
One of the earliest efforts to relate external nutrient loadings to
eutrophication was accomplished by Vollenweider (20). Vollenweider
plotted the phosphorus loading to a number of lakes as a function of the
mean lake depth to provide a basis for classifying the eutrophic status
of the water body. Dillon (21) has expanded this approach to include
the consideration of the effect of hydraulic detention time on nutrient
loadings and nutrient retention. Consideration of the hydraulic detention
time provides an improvement over the Vollenweider approach. This
improvement is realized because two impoundments with the same mean
depth may have considerably different detention times. For example, one
might be a run-of-the-river type impoundment while the other is a storage
reservoir. The eutrophic potential of the run-of-the-river impoundment
will be less due to the higher washout rate of nutrients.
The empirical analysis developed by Vollenweider and expanded upon by
Dillon for impoundment trophic classification assumes steady state and
completely mixed conditions. The equation used to develop the model
relates to the hydraulic flushing time, the phosphorus loading, the
phosphorus retention ratio, the mean depth, and the phosphorus.
concentration of the impoundment as follows :
L(1 " ^ = HP (5-18)
where :
2
L = phosphorus loading (Ibs/ft /yr)
R = fraction of phosphorus retained
p = hydraulic flushing rate (per year)
H = mean height (ft)
P = phosphorus concentration (Ibs/ft ).
The graphical solution is presented as a log-log plot of — ^r — — versus
H. Figure 5-24 (a) is a reproduction of Dillon's work on several lakes
in Canada. Lakes or impoundments which fall above the 20 Vg/1
concentration line tend to be eutrophic while those below the 10 yg/1
concentration line tend to be oligtrophic.
5-95
-------
(a)
(b)
on
I
VD
• •DILLON
O-SCHHOOR AND FKUH
40
8.0
O.B
0.45
o.os
!>0 100
MEAN DEPTH (METERS)
500 1000
i l i i l i i l i i i i i l
GRAPHICAL SOLUTION TO THE DILLON APPROACH
0 01 .02 .03 .04 .05 .06 .07 .08 .09 .10 II .12 .13 .14 .15 .16 .IT
p/SfiAMS-E.1)
^ V SO. METER I
TEST OF. IMPOUNDMENT
STEADY STATE AND COMPLETE MIXING
FIGURE 5-24
RELATIONSHIPS FOR EVALUATING THE STATE OF A LAKE
t
-------
In order to check the assumptions of steady state and complete mixing
made in the Dillon approach, a plot of Hp versus the P concentration
should be developed. This plot, shown in Figure 5-24(b), is for
various impoundments examined by Dillon. If the lake under study plots
near the line shown on Figure 5-24(b) it appears that the assumptions
associated with the Dillon techniques are valid. This indicates that
the phosphorus levels in the impoundment are in equilibrium with the
phosphorus inputs to the system. Satisfaction of this criteria would
support the application of the Dillon technique to estimate the eutrophic
status of the impoundment.
The application of the Dillon equation requires information on the
physical characteristics of the impoundment and observed or calculated
phosphorus loading data. The fraction of the phosphorus retained by an
impoundment can be determined either empirically of theoretically. The
empirical approach involves a mass balance calculation of the total
inflow phosphorus, the total outflow phosphorus and the amount that
remains in the impoundment. This difference may be estimated directly
by collecting sinking material at the bottom of the impoundment and
monitoring the phosphorus in the water column, or indirectly by monitoring
the inflow and outflow phosphorus. This empirical approach requires
data obtained through a comprehensive monitoring program which may not
be feasible within the planning effort.
In general, lakes which appear to be in the eutrophic stage on the basis
of the Vollenweider - Dillon analysis are candidates for more comprehensive
analysis aimed at determining the principal cause of the nutrient
enrichment so that alternative controls strategies can be developed.
Chapters 2, 3 and 4 discuss various methods for determining nutrient
sources in this case.
In situations where the Vollenweider - Dillon analysis would lead to the
classification of the lake as oligotrophic, the analyst should be guided
by other data in drawing conclusions regarding the status of the lake.
Simplified assessments of impoundment water quality conditions such as
this technique provide information having a level of reliability
appropriate only for gaining a perspective of water quality conditions.
5-97
-------
Results from these procedures should not be utilized for the design and
implementation of control strategies.
5.5.3 Analysis Methods for Water Quality Evaluations in Lakes
and Impoundments
An assessment of the expected level of pollutant concentrations in
impoundments using a number of initial estimating techniques are presented
in this section. The applicability and accuracy of these techniques are
dependent upon how closely the characteristics of the actual impoundment
fit the simplifying assumptions of the approach.
Three basic problem cases will be addressed. The first framework is
applicable to run-of-river impoundments having'small detention times.
The system is assumed to be at steady state with one-dimensional plug
flow and no vertical stratification. The second approach is applicable
to large reservoirs and lakes wherein the impoundment is assumed to be
completely mixed in the horizontal plane. Calculations for both vertically
mixed and vertically stratified systems will be presented. The third
set of estimates addresses pollutant concentrations in a two-dimensional,
localized area. These are for impoundment areas where there is
insignificant advective transport due to flow-through, wind currents, or
density gradients, and where there may be significant concentration
gradients around the point of discharge. Water quality estimates for a
cove area adjacent to an impoundment will also be presented. These
latter methods may also be used in analyzing estuaries and tidal rivers
discussed in Section 5.4.2 of this manual.
For each system, analyses will be presented for conservative substances
such as suspended solids, reactive substances such as coliforms and BOD,
and coupled reactions such as BOD-dissolved oxygen deficit.
5.5.3.1 One-Dimensional Plug Flow Systems
With run-of-the-river type impoundments, the same analysis that is used
to examine steady state water quality in free flowing streams and rivers
may be applied to the impounded portion of the river. The basic reactions
5-98
-------
and equations are the same; the major difference is the decreased velocity
and the correspondingly increased detention time in the impoundment.
The water is assumed to enter the impoundment with a flow Q, and
conservative, reactive or coupled pollutant concentrations, C , L , and
D , respectively. A constant loading rate, W, enters the impoundment at
the upstream end and a distributed (nonpoint) load, o>, may enter
throughout the length of the impoundment. For the analysis of the
upstream point source, a constant or an expanding cross-sectional area
may be used to characterize the geometry of the impoundment, whereas the
analysis of the distributed load is limited to a constant cross-
sectional area.
The solutions for pollutant concentrations as a function of distance, X,
in the impoundment are shown in Table 5-20. The reaction rate of the
first system is K , the reaction rate of the second system is K , and
r ' a
the rate describing the interaction between the two systems is K,. For
a BOD-DO deficit system where all of the BOD is removed by oxidation
(rather than settling), K, = K . Typical reaction rates are shown in
Table 2-19.
For the BOD-DO deficit system, K is the reaeration rate of dissolved
a
oxygen in the river. It is best estimated in impoundments by using
equation (5-6). Temperature correction of these values is accomplished
using methods described in Section 2.6.3.4.
For the BOD-DO analysis, the magnitude of the ultimate oxygen demand
(W ) is entered in the BOD system and, as appropriate, the deficit
loading is included in the DO deficit system (W2). The ultimate oxygen
demand is comprised of both carbonaceous and nitrogenous components
which may be estimated to be 1.5 x W(BOD ) and 4.57 x W(NH3-N).
For the point source solutions of Table 5-20, f (x) will depend upon the
distance-area relationship assumed for the impoundment. The relationship
between cross-sectional area and distance downstream may have many
functional forms. The most common for free-flowing streams is the
constant cross-section, particularly when relatively short distances and
small drainage areas are considered. A constant area is designated as
5-99
-------
TABLE 5-20
SUMMARY OF STEADY STATE SOLUTIONS FOR POLLUTANT CONCENTRATIONS
IN A FLOW-THROUGH IMPOUNDMENT
DISTRIBUTED SOURCE
w
Q — <
Conservative
Reactive
Coupled
dam
> — x — - Q
c = c + W/Q
-KrfCx)/UQ -Kr£Cx)/UQ
L = L e + W/Q e
-KafCx)/Uo
D = D e
-KrfCx)/Uo -KafCx)/Uo
i. T . f> r i
' Lo ' K -K C° ° -1
a r
-KrfCx)/Uo -KafCx)/Uo
+ W/n ^ fr- r- ~\
^ ' K -K *- ~
a r
(jd darn
i i i i i i i i i i i i i i ) i
Q — — o — x ^- Q
c = CQ + ^x/Q
-Krx/U -Krx/U
L " V + AJT Cl - e )
-Kax/u
D = D e
K, -V/U -V/U
i T fr r 1
o ' K -K ' C° ° J
a r
K -KaX/U -V/U K-K
+ to d f r a
+ AK ' K -K CK C "C K
r a r a a
en
i
O
o
-------
A . For greater distances, larger drainage areas, or impounded rivers,
the exponential and linear forms may be represented:
A
A(x) = x (5-19)
A(x) = A eaX (5-20)
In these equations, 'A is the cross-sectional area at distance x, which
is measured from the origin of the coordinate system. In equation (5-19)
x is the distance from a hypothetical origin to the location of A . In
equation (5-20 )A is located at x = 0. In both cases, the location of A
may be arbitrarily assigned. Examples of constant, linearly and
exponentially increasing representations of the area are shown in Figure
5-25. The appropriate expression for f (x) for use in Table 5-20 will
depend upon the area-distance relationship assumed and is shown below.
Expression for f(x)
Area-Distance Relationship
Constant Linear Increase Exponential Increase
2 2
x - x ax. ,
e
—sr- ~
o
where: a is an empirically developed constant.
Note that U , the velocity at the beginning of the impoundment, is used
in the solutions presented in Table 5-20 and that for the linearly
expanding case, x = 0 at the location which is? a distance x before the
beginning of the impoundment. To apply the solution equations for a
distributed source, a constant cross-sectional area must be assumed. If
the area varies considerably, the impoundment may be divided into
several constant-area segments and the analysis performed within each
segment.
5-101
-------
DAM
DISTANCE
AREA,A
EXPONENTIAL, A = Aoeox
A0
LINEAR, A = —S- X
X0
CONSTANT, A = A0
DISTANCE, X
FIGURE 5-25
FUNCTIONAL AREA REPRESENTATIONS
5-102
-------
5.5.3.1.1 Dissolved Oxygen Deficit Determination
The solutions for dissolved oxygen deficit obtained from Table 5-20
include only the effects of BOD loads and upstream BOD and DO deficit
concentrations. They do not include the effects of the oxygen demand
imposed on an impoundment by benthic material and algal respiration, and
the input of dissolved oxygen from algal photosynthesis.
The components of the benthic material which exert an oxygen demand
include inflow organic material, settled biomass, and chemical constituents
which undergo oxidation-reduction at the sediment-water interface.
Except for impoundment areas that receive direct discharges of settleable
wastes, the benthal oxygen rate, SD, may be estimated to be on the order
2
of 0.3 to 3.0 gm 02/m /day. Site specific data is normally required to
refine the estimate of SD. The monitoring appendix provides guidance in
D
developing this type of data.
When algae are present in streams, there is a diurnal variation of
dissolved oxygen due to varying photosynthetic oxygen production during
the day. The primary factor that governs the photosynthetic oxygen
production of algae is the quantity of solar radiation the algae receive.
The average relative oxygen production may be estimated as follows:
e a S) (5-21)
rs V1 fp
where:
-KeH
a = e
P is the light saturated rate of oxygen production
o
I is the average light intensity during the daylight portion of
cl
the day
I is the light saturated intensity
o
f is the number of hours of daylight
T equals twenty-four hours
K is the extinction coefficient
6
H is the river depth.
5-103
Pav
P
s
2.718 f ,
~ K H T *•<
Ken *p
-al /I
a s
-------
V
P in equation(5-21)is the average algal oxygen production over the
av -1
entire day. The extinction coefficient ranges from 0.1 - 0.5 m for
very clear impoundments, from 0.5 to 2.5 m for moderately turbid
_-^
waters, and greater than 2.5 m for very turbid waters.
The ability to calculate the absolute oxygen production rate depends
upon the estimation of P , the light saturated rate of oxygen production.
o
A correlation between P and the concentration of chlorophyll "a" taken
o
as a measure of the algae population density may be used to estimate P :
o
P =0.25 Chi (5-22)
s a
where:
P = mg oxygen produced/I/day
o
Chi = Chlorophyll "a" concentration in jig/1.
3-
Thus, by measurement of the chlorophyll "a" concentration, the incident
solar radiation I , the length of daylight f, the extinction coefficient
3-
k and the depth H, the average daily rate of photosynthetic dissolved
6
oxygen production may be estimated.
Although algae produce oxygen by photosynthesis, they also utilize
oxygen for respiration. The respiration rate, R, has also been related
to chlorophyll "a" concentration:
R = r(Chl ) (5-23)
a
where:
R = mg oxygen utilized/1/day
Chi = chlorophyll "a" concentration in vJg/1
3-
r = constant ranging from 0.005 to 0.030 with 0.025 a common
value (22) corresponding to a 10 to 1 ratio of P to R.
5
The respiration rate is known to vary considerably and depends on the
nutrient concentration and age of the culture. Hence the average daily
algae respiration calculated from equation (5-27) is subject to some
degree of uncertainty.
5-104
-------
The estimates of the benthal oxygen demand, algal photosynthesis and
respiration may be incorporated into the estimate of the average DO
deficit by the following equation:
, SD -K f(x)/U
D " IT CIT - pav + R> C1 - e > C
a
This indicates the average in the impoundment, but not the diurnal
variation around the average. The diurnal range of dissolved oxygen, AQ
(mg/1), due to algal effects may be estimated (23) as:
4Q - Pav Cl - f-) CS-25)
EquationC5-25) requires that K be less than about 0.2 day" to be
3-
applicable. This should be true in most impoundments due to their depth
and low velocities.
5.5.3.1.2 Location of Maximum DO Deficit Due to
Point Source
Guidelines have been presented for estimating the steady state, spatial
distribution of dissolved oxygen deficit in a run-of-the-river impoundment.
The DO deficit due to the various sources may be added together and
plotted as a function of distance, x, along the impoundment to determine
the location and magnitude of the maximum DO deficit. A simpler approach
is available for estimating the maximum DO deficit response due to a
single point source. The maximum deficit, D , is:
Krln(Ka/Kr)
°c = rCe > (5'26:)
cl
The determination of the location of the maximum DO deficit, x£, depends
upon the distance-cross-sectional area relationship assumed, and may be
estimated for each as:
U K
x = ° ln(r£), for constant area (5-27)
c VKa Ka
5-105
-------
2U x K
X =
C V
_K -, ln(—), for linearly expanding (5-28)
a' a area
aU K
r.
• r a- a T5-291
x = = , for exponentially l }
expanding area
A graphical estimate of D due to the point source, W, may also be made
\*r
using Figure 5-26 (8). The ultimate oxygen demand load is.input on the
upper right axis and the solution is determined by moving counterclockwise
K
from the flow, to the maximum BOD concentration, to , where = •=-,
Ka
(this analysis assumes K = K,), to the maximum DO deficit. The location
of the maximum deficit should still be calculated, however, to insure
the maximum deficit occurs within the impoundment.
5.5.3.1.3 Determination of DO Concentration
Once the dissolved oxygen deficit has been determined, the DO concentration
may be calculated. The dissolved oxygen saturation concentration, C
s,
may be determined in streams, impoundments and marine systems from Figure
2-19(b) (pg. 2-92). Chloride concentrations may generally be assumed to
be near zero in lakes and impoundments. The DO concentration', C, then
equals C -D. Applications of the foregoing estimating technique are
shown in Table 5-21.
5.5.3.2 Completely Mixed in the Horizontal Dimensions
The second set of impoundment systems analyzed are the large reservoirs
and lakes having long detention times. These impoundments are assumed
to be completely mixed in the horizontal directions. Estimating procedures
are presented for vertically mixed and vertically stratified systems.
The impact of external pollutant loads can only be estimated for
conservative or slowly reacting substances, as more rapidly reacting
constitutents will not have a chance to be mixed throughout the
impoundment. Estimates for dissolved oxygen concentrations are presented
for assumed uniform rates of benthal demand, reaeration, algal
photosynthesis, and respiration throughout the lake. The algal effects
5-106
-------
C/l
I
8765432 I
MAXIMUM DISSOLVED OXYGEN DEFICIT (mg/l)
100
1,000 10,000
ULTIMATE OXYGEN DEMAND (LBS/DAY)
SOURCE^8)
FIGURE 5-26
SIMPLIFIED ASSESSMENT OF DISSOLVED OXYGEN DEFICIT IN IMPOUNDMENTS
AND RIVERS
-------
TABLE 5-21
EXAMPLE OF DO DEFICIT PROBLEM: RUN-OF-THE-RIVER
IMPOUNDMENT AND DOWNSTREAM EFFECTS
U) = 1 OOP. Ib/day /mile UOD
w =
Ao
Y//////-/////////////X
15,000 Ib/day UOD . •«.
— Q = 570 cfs
= 1000 ft2 -~-~- S,
H 1
I- in mi i
T =
Dam C =
Q =
A = 21,000 ft2
20DC
9.0 mg/1
570 cfs
(Fig. 2-19)
LA = 570
ft2
Impoundment
Downstream
Height Water Falls over Dam = H. = 10 ft
Average H = 7 ft = 2.1 m
Average A = 570 ft2
Average U = 1 ft/sec = 16.4 mi/day
Kr = Kd = 0.25 day"1
Ka = 0.75 day"1
Pav = R = SB = 0
Average H = 12.ft = 3.6 m
Average A = 5700 ft2
Average U = 0.1 ft/sec =1.64 mi/day
Kr = Kd = 0.-25 day"1
Ka = 0.16 day"1
Pay = 1.3 mg 02/l/day
f = 14 hr
R = 0.4 mg 02/l/day
SB = 2 g 02/m2/day
Assumed Upstream UOD and DO Deficit = 0
Check Location of Maximum Deficit in Impoundment due to Point Source.
1) Assume Constant Area = 5700 ft (Eq. 5-27)
Xc = (0.25-0.16) ln
-------
TABLE 5-21
(Continued)
EXAMPLE OF DO DEFICIT PROBLEM: RUN-OF-THE-RIVER
IMPOUNDMENT AND DOWNSTREAM EFFECTS
Xc = 8.1 mi
(At location of maximum point source
deficit)
a) Deficit di
See preceding sheet
D= DC = 2.20 mg/1
X = 10 mi
(In impoundment, at dam)
10 to Point Source
See Table 5-20 _Q_25 g w _„_„ x 1Q
15,000 0.25 1.64 1.64 .
" ~ 570 X 5.4 * (0.16 - 0.25) IC C J
=2.16 mg/1
b) Deficit due to Distributed Source (Table 5-20)
x
D =
=
S
DO
Ib/ft mi 0.25
5700 X 0.25 X (0.16 - 0.25)
-0.16 x 8.1 -0.25 X 8.1
0.25 1.64 1.64
0.16 C C
(0.16 - 0.25) ,
c) Deficit due to
-0.16 x 8.1
1 (_?_! fl . e L64 }
0.16 C3.6J C1 6 J
1.9 mg/1
d) Deficit du
-0.16 x 8.1
0.16 t'1-3 ' °'4) C1 ° J
-3.1 mg/1
e) Dissolved Oxygen Conce
= Cs - ED = 9.0 - (2.2 + 0.8 + 1.9)
= 4.1 mg 02/1
1000 X 3.0 0.25
5700 X 0.25 X (0.16 - 0.25)
-0.16 x 10 -0.25 X 10
0.25 1.64 1.64 0.16 - 0.25
X 0.16 C " C ' 0.16
Benthal Demand (Eq. 5-24)
-0.16 x 10
12 1 * 64
0.16 3*6
B to Algae (Eq. 5-24)
-0,16 x 10
1 1 64
" 0.16 l J L J
= -3.5 mg/1
ntrations without Algal Effects
DO = 9.0 - (2.2 + 1.1 * 2.2)
= 3.5 mg 02/1
D0a = 9.0 - (2.2 + 0.8 + 1.9 - 3.1)
f) Dissolved Oxygen Concentrations with Algae
Range of diurnal variation = A0= Pay (1 - f/24) = 1.3 (1 - 14/24) = 0.54 mg/1
f.l) Daily Average Concentration
D0av = 9.0 - (2.2 + 1,1 + 2.2 - 3.5)
=7.0 mg 02/1
f.2) Minimum Daily Concentration
DO = 7.0 - 0.54/2
= 6.7 mg 02/1
(Eq.~ 5-25)
7.2 mg 02/1
D°av - V2 = 7'2 - °'54/2
6.9 mg 02/1
5-109
-------
may be qualitatively related to external nutrient loads using the
Vollenweider and Dillon techniques previously presented.
The first case analyzed is the completely mixed (horizontally and
vertically) lake with a conservative or slowly reacting (in relation to
the detention time) substance. Examples of slowly reacting substances
which may be relevant for this type of analysis include pesticides and
radioactive materials. The equations for the lake concentration are
shown in Table 5-22. A constant pollutant load, W is assumed to enter
the lake. The lake has a volume, V, an outflow, Q, initial conservative
and reactive pollutant concentrations, C and L , and for the reactive
substance, a reaction rate K . If the inflow is estimated from the
upstream drainage area, the net evaporation should be subtracted to
determine Q. The impoundment does not reach a steady state rapidly if
the detention time is long, and the time variable equations of Table 5-
22 may be used to estimate the buildup over time. Also shown is the
lake response to a load increasing or decreasing linearly with time.
Since this loading condition never reaches a constant value, the receiving
water concentrations never reach a steady state concentration. Application
of these equations are shown in Table 5-23.
5.5.3.2.1 Vertical Stratification
Stratification occurs when the flow through an impoundment is insufficient
to overturn the temperature and density gradients discussed in Section 5.5.1,
due to sources and sinks of heat, such as solar radiation, evaporation
and conduction. The temperature patterns in a lake follow a seasonal
pattern, and prediction of the temperature profile requires analysis
techniques beyond the scope of this' manual.
In impoundments with long detention times, concentrations of solids-
associated pollutants vary with depth due to settling. This process may
be characterized for conservative substances by the following equation (24) :
ZV /E
C(Z) = CQe S V (5-30)
5-110
-------
TABLE 5-22
CONCENTRATIONS IN LARGE, COMPLETELY MIXED IMPOUNDMENT
Constant Load
W
W
W = W
Linearly Increasing
or Decreasing Load
W
W
W = W +03t
o—
Conservative
- Concentration
vs.
Time
Coe
W
'if'1
w
W
- Steady State
Slowly Reactive
Note: a = * + K
- Concentration
vs.
Time
Loe
-at
W
W
T -at o ,.. -at.
Loe + ^V C1 ' 6 D
± » (ot + e~<* _
- Steady State
aV
5-111
-------
TABLE 5-23
EXAMPLE, COMPLETELY MIXED IMPOUNDMENT
(See Table 5-22)
Cons ervat ive, TDS
= 108,000 Ib TDS/day
Slow Decaying Pesticide, Trial late
= 1080 Ib Triallate/day
Kr = 0.23 year
"1
= 6.3 x 10~4 day
"1
Q = 100 cfs
Assume constant loads beginning at time t = 0
1) Equilibrium TDS Concentration, G = c
6 Q
c = 108,000 = 200 mg/1
e 100 x 5.4 6/
2) Buildup over time of TDS
detention time
Q/V =
t C
(years) (mg TDS/1)
-1
- e
1 year
-^/V) - 100
0
0.5
1.0
100
139
163
t
(years)
2.0
3.0
+ 200
Qng TDS/1)
187
195
3) Equilibrium Triallate Concentration, L = —rr
a
= (1 + 0.23) = 1.23 year
-1
L = 1080/(1.23 x 3.17 x 10"8 year/sec x 3.15 x 109 x 5.4)
6
= 1.6 mg Triallate/1
5-112
-------
where C(Z) is the concentration at a depth Z, C is the concentration at
the surface, V is the settling rate, and E is the vertical diffusion
coefficient. Settling rates for suspended solids range from 0.1 to 30
in/day depending on the density and particle size (25 ) while E will
2 2 'V
range from 0.1 to 10 m /day with 1 m /day frequently used (26). Examples
of exponentially increasing concentrations with depth are shown for Lake
Livingston, Texas in Figure 5-27.
Large impoundments also tend to be vertically stratified with respect to
dissolved oxygen concentrations, because the lake surface is a source of
oxygen from reaeration, the bottom is a sink of oxygen due to benthal
demand, the production of oxygen from algal photosynthesis varies with
depth due to decreasing light penetration with depth, and there is
limited vertical exchange of oxygen in the water column. If the lake is
considered to have one zone (that is, a constant E ), the dissolved
oxygen deficit profile may be estimated by the following (23):
BT nu T 7
ni-/ 1 - n i L i i Ktl n i L n ^ ~n
^l^J v I1 ' -c J v *- c v1 ~ oijJJ
K. C K. E /rl
L V L V
P f
S
K.K T
L e p
-K H KT . "KeZ -K H
1 r e i L f1 " e -r e 1
v e J
(5-31)
Guidelines for estimating SR, R, P , —, K , and E have been previously
o S 1 6 V
p
presented, and may also be applied here. Note this simplification
Ia
assumes — = 1, (see equation (5-21); and there is some error when it
does not. KT is the oxygen transfer coefficient (KT = HK ) and may be
L La
estimated as follows for the horizontally mixed impoundments (27):
K = 0.362 s 1/2 for s .< 5.5 m/sec
W 9 W f^
K. = 0.0277 s for s > 5.5 m/sec L
L w w —
where K, is measured in m/day and s is the wind speed in m/sec. An
application of this technique is shown in Table 5-24. Note that this is
only recommended for an initial order-of-magnitude estimate, and more
sophisticated time variable models are required for a more accurate
estimate.
5-113
-------
o
LJ
LJ
L-
0.
LJ
Q
O.Z
0.4 0.6 0.8 1.0
NH3-N,TOTAL PHOSPHATE (mg/l)
I
6 8 10
SI , DISSOLVED OXYGEN (mg/l)
12
14
| I I I I I I I I
22 23 24 25 26 27 28 29 30
TEMPERATURE (°C)
FIGURE 5-27
WATER QUALITY VARIATION WITH DEPTH IN LAKE LI VINGSTON.TEX AS
5-114
-------
TABLE 5-24
EXAMPLE HORIZONTALLY MIXED IMPOUNDMENT
DO DEFICIT PROFILE
Wind = sw= 5 m/sec — f = 14 hr Sg = 0.5 g 02/m2/day
T = 24 hr EV = 1.0 m2/day
H = 40 ft Chi = 20 yg/1
H = 12 m K = 0.2 ft"1 = 0.67 nf1
e
T = 20°C (Assume Unif orm) , C =9.0 mg/1
1) Estimate KL (Eq. 5-32)
KL = 0.362 (5)1/2 =0.81 m/day
2) Estimate P (Eq. 5-22)
P =0.25 (20) = 5.0 mg 09/l/day
O £t
3) Estimate R (Eq. 5-23)
R = 0.025 (20) = 0.50 mg 02/l/day
4) Determine DO Deficit at Different Depths (Eq. 5-31)
nry-* - °-5 ft A 0.81 Z^ ^ 0.50 x 12 ,.. 0.81 Z ,, Z ...
D(-Z) ~ OTST C1 + 1.0 J OT~ C1 * 1.0 (1 " 2 x 12-*-1
5.0 x 14 fn -0.67 x 12 0.81 f\ - e"°-67Z -0.67 x
— Q + - rt I rt si ~ "6
O.Slx 0.67 x 24 I" w 1.0
D(Z) = -3.84 + 6.5Z - 0.25Z2 + 6.5e"°'67Z (Z in meters)
Z Def Z Def
(meters) (mg/1) (meters) (mg/1)
0 2.7 3 14.3(anaerobic)
1 5.7 >3 (anaerobic)
2 9.9
^]
5-115
-------
The equation presented for the DO deficit profile assumes one zone in
the lake. Often the stratification becomes so severe that two zones are
formed when a thermocline divides the upper warmer layer and the lower
colder layer of the lake. When this occurs, the lower layer may become
anaerobic, resulting in regeneration of inorganic nitrogen and phosphorus
from the sediment. The DO profile shown for Lake Livingston, Texas, in
Figure 5-27 demonstrates the increasing deficit with depth, leading to
anaerobic conditions in the lower portion of the water column. In the
lake, the thermocline occurs at a depth of approximately 30 feet.
5.5.3.3 Localized Pollutant Concentrations
The third set of problems analyzed deal with the pollutant concentrations
around a localized load to an impoundment. The impoundment is assumed
vertically mixed in the vicinity of the waste source and mass is assumed
to be transported in the impoundment only by dispersion (insignificant
effect from flow-through or currents). The load, W, enters the impoundment
over a width, 2a, and a depth, H, the depth of the impoundment in the
vicinity of the waste source. Figure 5-28 depicts the problem and the
curve (28) for estimating the concentration at the shortline of the
impoundment at the midpoint of the load, C(0,0). The load may be
due to a tributary, a cove where a treatment plant discharges, or a
distributed source such as septic tanks or a marsh area. If the load is
assumed to be distributed, that is equivalent to o)(lb/day/mile) in Table
5-20 for the run-of-the-river impoundment, W may be calculated as W
= o)2a . The dispersion coefficient, E, is for dispersion in the horizontal
4 72
directions. E will range generally from 10 to 10 m /day in lakes, and
the lower values are typical of the near-shore region. Once C(0,0) has
been determined, the concentration at points along the shore may be
estimated from Figure 5-29. The concentration at a given distance
perpendicular to the shore (along the x axis) will be less than the
concentration at the same distance along the shore (along the y axis).
Therefore, Figure 5-29 may also be used for a conservative estimate of
pollutant concentration profiles perpendicular to the shoreline.
5-116
-------
tn
5,0
4,0
3,0
2,0
1,0
0,01
W» WASTE WAD IIDl/doy)
Ei PISPgRSIPN CPEFP,
K » PESAY RATE ( dor1')
H« WATER DEPTH (FT)
I I I I I I I I I I I I I I I I I f t ( t t ( f t
0,05 0,10
,0,5
H
1,0
5,0 10,0
FIGURE 5-28
MAXIMUM ALONGSHORE CONCENTRATION
-------
(J-l
1.0
5.0
y=y/o
NON-DIMENSIONAL ALONGSHORE DISTANCE
10.0
50.0
FIGURE 5-29
ALONGSHORE CONCENTRATION ESTIMATE
-------
To determine the concentration of a coupled substance, such as DO deficit,
the following equation may be used (29):
K,
D = •=-£- (C - C ) (5-33)
a r
where D is the deficit at the point of interest, C.. is the concentration
of BOD calculated at the point of interest using Figures 5-28 and 5-29,
and C2 is the BOD that would be calculated at the point of interest with
K = K . Applications of this technique are shown in Table 5-25.
IT d.
If a wasteload is discharged into a short cove near the interface of the
impoundment, the previous analysis may be used. If the cove is long and
the discharge is far from the impoundment interface, however, significant
reaction may occur in the cove. In this case, the following procedure
should be employed.
The waste load' is assumed to enter the water at the upstream end
of the cove as shown in Table 5-26. The equations for each case for the
reactive and sequentially reactive concentrations in the cove are shown
in the respective Tables. Note that, as before, BOD and DO deficit
loads may both be analyzed. The pollutant is assumed to be transported
within the cove by advection (Q) and dispersion (E). The dispersion
coefficient should be of approximately the same magnitude as within the
4 72
impoundment: E = 10 to 10 m /day with the higher values appropriate
for coves with significant advective flow. The concentration from the
load is assumed to be reduced to nearly zero (5 percent of the maximum
cove concentration) at the cove-impoundment interface, and thus the load
has a negligible effect on the main portion of the impoundment. For
this assumption to be true the cove must be "long", that is, the distance
from the load to the impoundment, b, must be greater than 3/|j,| for the
reactive analysis (j.. is defined in Table 5-26) and b must satisfy the
requirements indicated in Figure 5-30 for the coupled DO deficit analysis.
The reaction rates may be taken from Table 2-18 and the reaeration may
be estimated from the wind speed in equation(5-32)for coves with an
advective velocity (U = §.) less than 0.1 ft/sec, and from quation(5-6)
5-119
-------
On
I
NJ
O
TABLE 5-25
EXAMPLE OF SHORT COVE ANALYSIS
Actual
Short
Cove
I
2a
Idealized
Short cove assumed well mixed
with concentration approxi-
mately equal to that calcu-
lated at (0,0).
a = 100 ft
H = 5 f t
E = 0.1 mi /day.
= 32.3 ft2/sec
Coli: K = I/day
BOD-DO: Kr = Kd = 0.25/day
Reaer:
m/day =2.66 ft/ day (Eq. 5-32)
K, = K./H = 2.66/5 = 0.53/day
3 L
Wind Speed = 5 m/sec, K, = 0.81
Coliform Analysis
Use W = 10 cfs x 100,000 MPN/100 ml
I/day x (100
I
0.1 ml2/day x (528°
= 0.060
A C(0,0)/(W/2HE) = 2.50 (Fig. 5-28)
0(0,0) = C,H = 2.50 x (10 cfs x 100,000 MPN/100 ml) . „,„ MPN ^
"** 2 x 5 ft x 32.3' ftVsec IUU
For a level of 1000 MPN/100 ml,
C(0,Y)/C(0,0) = 1000/7740 = 0.13
$ Y = Y/a = IS ' (Fig. 5-29, for ct = 0.06)
.• Alongshore, beyond approximately Y = jf.1500 ft, coliforra levels
would be less than 1000 MPN/100 ml. In the offshore (x)
direction, coliform concentrations would decrease even more
rapidly than in the y-direction.
se UOD=
"DEF =
At X » 0, Y
Dissolved Oxygen Deficit Analysis
10 cfs x 165 mg-UOD/1 x 5.4 ^1^/1 = 891°
10 cfs x 5 mg-DEF/1 x 5.4 = 270 Ib/day
0: Max UOD concentration is:
a(Kr)='Kra /E s/0.25 x 100 /(O.I X 5280 ) = 0.030
.-. L(0,0)/(WUOD/2HE) = 2.95 (Fig. 5-28)
L(0,0) = 2.95 x 8910/(2 x 5 x 32.3 X 5.4) = 15.1 mg-UOD/1
At x = 0. y = 0:
a] : Max DO Def due to UOD is:
DUOD = CKd/CKa ' V5 ' (LCKr5 " L(Ka)5 (See Eq> 5'33)
As above, L(Kr) = 15.1 mg/1
x 1002/(0.1 X S2802) = 0.044
LfKa)/(WUOD/2HE) = 2'72
(Fig. S-28)
L(Ka) = 2.72 x 8910/(2 x 5 x 32.3 x 5.4) = 13.9 mg/1
DUOD = (°-25/C0.53 - 0.25)) • (15.1 - 13.9) = 1.1 mg DEF/1
b) : Max DO DEF due to DEF Load is:
•• D
= 0.044 as above 6 DDEF/(WDEF/2HE) = 2.72 as above
2.72 x 270/(2 x 5 x 32.3 x 5.4) = 0.4 mg DEF/1
DEF
c) Total DO Def is 1.1 + 0.4 = 1.5 mg/1
At X = 0. y = 1500 ft (Y = 15)
L(K ) = 15.1 x 0~72 = 3.32 mg/1; L(K ) = 13.9 x 0.17 = 2.36 mg/1
T , 3.
DUOD = CO. 25/ (0.53 - 0.25)) • (3.32 - 2.36) = 0.96 mg DEF/1
"DEF
= 0.4 X 0.17 = 0.07 mg DEF/1
Tot. DO DEF is 0.96 + 0.07 = 1.0 mg/1
Note: At y = 15, although coliform cone, have decreased to 13% of its
peak, the DO fief has only decreased to 67% to its peak value.
-------
tn
I
"long"
cove
Reactive
Sequentially
Reactive
b * bMIN
see Fig. 5-30
Q=£low (c£s)
U=velocity =
A=cross-secti
area (£t )
W=mass discha
(lb/day)
TABLE 5-2.6
EQUATIONS FOR LONG COVE ANALYSIS
Actual V Idealization *• ''
y ;
y impoundment * |— h— \
1 \S Y'""'' 's^f
QW^ Q ; • I-
*^>^ """' : ;'"
w iX. w ~" — b " ' A = ^
TV W
r r Jl 1 2
L - 1^ e , where ^ = — . J—
t ^
J«X K1 « JT^ I'HD. Jo" "o •?
n -i n n 4 •*• T nx c •'•^n i.ih^t-i- n —
D o c K,-K ' Lo c " Cl+m -1 c ' whcrc o ' Q ' H-m
1-m 1+m D K,-K ..
Description of symbols with typical units
-1 / 2
K^decay rate, system 1 (e.g. BOD) (day 1 m. =/l + 4K.E/U
D
^ (fps) K_=reaction rate, system 2 (e.g. reaeration rate). }. = (U/2E).(l-m.)
onal K19=reaction rate between systems 1 § 2, (e.g. E = dispersion coeff.
-1 2
deoxygenation rate Kd) (day ) (mi /day)
rge
-------
= 0.05 Dc
X
50
40
30
20
15
10
1IIIIITT
•n?1
I I I I I I I
i i
I 1
0.3 0.5
0.9
K2/K,
2.0 3.0 4.0
FIGURE 30
MINIMUM LENGTH FOR DISSOLVED OXYGEN DEFICIT
ANALYSIS IN "LONG"COVE
5-122
-------
when the advective velocity is greater than 0.1 ft/sec. Applications of
the "long" cove analysis are shown in Table 5-27.
5.5.3.4 Water Quality Downstream of Impoundments
The degree to which impoundment releases impact downstream water quality
depends upon the.quality of the impounded water at the dam and the
characteristics of the downstream channel. The release is assumed to
have one-dimensional plug flow, and the equations for conservative,
reactive and coupled concentrations in Table 2-17 may be applied.
Another consideration in the downstream analysis is the manner of release
from the impoundment. If the water flows over a dam, there will be
reaeration which decreases the dissolved oxygen deficit. This effect
may be estimated by the following equation:
D - D. = 0.037 H,D (5-34)
a b d a
where D is the deficit above the dam (in the impoundment}, D, is the
a D
deficit below the dam, and H, is the height the water falls (ft). This
formulation was developed for the Mohawk River and Barge Canal, and is
valid for dams up to 15 feet high and temperatures in the range of 20
to 25°C. For example, if the deficit concentration above the dam is 2.0
mg/1 and the dam height is 8 feet, the dissolved oxygen deficit
concentration below the dam is estimated to be:
Db = 2.0 - 0.037(8)(2.0)
Db = 1.4 mg/1
If the impoundment release is from the bottom of the dam, other factors
must be considered. As previously indicated, the deeper layer of
impoundments, particularly larger stratified reservoirs, tend to be
colder, lower in dissolved oxygen, higher in solids related pollutants,
and may possibly contain anaerobic by-products. Releases of this type
may result in serious downstream water quality problems, and should be
carefully monitored.
5-123
-------
cn
I
K)
TABLE 5-.2 7
EXAMPLE OF LONG COVE ANALYSIS
////////////_/[
-g—•[ "lout" cove'
I b'-'l'o'm'i'."] Tributary InfloMQ)
I* *| SO cfs » av. summer flow
ig) 10 cfs - design low flow
E • 0.2 nl2/day, *mll • I/day, Kf • Kd > o.25/day, KO . O.S/day
*coll • 1 cfs x 100,000 MPN/100 nl, K^JJ . 2700 Ib/day, HDEF negligible
COIIFORH AHAIYSIS
For Q • 10 cfs
U • 10 cfs/CS ft x 200 ft) • 0.01 ft/sec • 0.1636 mi/day
"2 • /I + 4 X 1 x 0.2/(0.1636)2 . /I * 29.89 • S.558
) ' CU/2B)(l-m) - 0.1636 mi/day (1.5-Ssg, , .
2 x 0.2 miVday
Check: b - 10 Bi >.3/|j| . 3/1.864 . 1.6 ni OK (Fig.S-2«l
Max. cone. « x . 0 . £ . 2 . 1 efs x 100.000 MPN/100 nl 2_
q i » m 10 cfs i « s.:
> 30SO
HPN
101) ml
For Q » 50 cfs Using same procedure as above, U « 0.818 mi/day.
n • 1.432, j - -0.98S7/mi, 3/|j| • 3 mi, max. cone - 1610 HPN/100 ml
DISSOLVED OXYGL1 AK/llYSIS
For Q - 10 cfs
POP: Oj " /I » 4 x 0.2S x 0.2/(0.1636)2 - /I * 7.472 • 2.911
Jj " !0.1636/(2 X 0.2)1 (1-2.911) - -0.7816/ml
Checs: b • 10 mi > 3/0.7816 - 3.3 mi OK
' cfs-mj/1
PO PEF: »
O.S x 0,2/(0,1636)2 • A * 14.94 • 3.99J
• (0.1636/-C2 X 0.2)) (1 - 3.993) - - 1.224
•mcfei^.feHfe
1-2.911 1+3.993J
Check bmln: For HJ • 7.47, Kj/Kj • 2,
,0.1636
0.4619 mi
bnln/Xc • 12 and bmln « 12 X 0.4619 • S.5 mi < 10 mi - OK (Fig-S-30)
I
Max PO PEP cone * X • X
-0.7816 x 0.4619 ,1 * :
-1.224 x 0.4619
• 6.45 Kg- DO Def/1
For Q • 50 cfs Using same procedure is above:
POP! Hj • 0.2989, Bj - 1.140, Jj • -0.2863/ni, 3/0.2863 • 10.4 mi » 10 «i, OK
Max. UOD cone. - 9.34 ng-UOO/1
PO
1,264, J - -0.5399/ni, X - 2.279 mi,
16 Bi.
Since b • 10 ml < b . « 16 ni, "long" cove analysis is inappropriate
and would lead to inaccurate results in the cove. A higher level analysis
is required which incorporates the cove and impoundment simultaneously.
-------
5.6 References
1. Hydroscience, Inc., Water Quality Analysis of the Jackson River, for the
Westvaco Corporation, Covington, Virginia (June 1976).
2. Hydroscience, Inc., Development of a Steady State Water Quality
Model for New York Harbor, for Interstate Sanitation Commission,
(October 1975).
3. Hydroscience, Inc., Effects of Dispersion Upon Storm Pulses in a Stream,
Internal Technical Memorandum, (December 1976).
4. Hydroscience Inc., Storm Water Management Model (In Progress).
5. Hydroscience, Inc., Deterministic-Stochastic Stream Modeling, Internal
Research and Development Report, (June 1976).
6. Bendat, J.S., and A.G. Piersol, Random Data: Analysis and Measurement
Procedures, Wiley-Interscience (Pub), New York, N.Y., (1971).
7. Thomann, R.V., Systems Analysis and Water Quality Management,
Environmental Research and Applications Inc. (Pub.), New York, N.Y.
(1972).
8, Hydroscience, Inc., Simplified Mathematical Modeling of Water Quality,
Environmental Protection Agency Publication (March 1971) .
9. Tide and Current Tables, Published by National Oceanographic and
Atmospheric Administration.
10. Hydroscience, Inc., Technical Review of the Central New York Regional
Planning and Development Board's Phase I Water Quality Studies,
Letter Report, (July 1976).
5-125
-------
11. Hydroscience, Inc., Evaluation of Discharge Alternatives For South
Bay Dischargers, prepared for Bechtel Corp., (December 1975).
12. Fan, L.N., Turbulent Buoyant Jets Into Stratified or Flowing Ambient
Fluids, W.M. Keck.Laboratory of Hydraulics and Water Resources,
Publication No. KH-R-15, (June 1967).
13. Rawn, A.M., F.R. Bowerman, and N.H. Brooks, Diffusers For Disposal
of Sewage in Seawater, Trans. A.S.C.E., Vol. 126, Part III, (1961).
14. Rawn, A.M. and H.K. Palmer, Predetermining the Extent of a Sewage
Field in Seawater, Trans. A.S.C.E., Vol. 94, (1930).
15. Hart, W.E., Jet Discharge Into a Fluid With a Density Gradient., Trans.
A.S.C.E., Vol. 128, Part I, (1963).
16. Tables For Rapid Computation of Density and Electrical Conductivity
of Sea Water, U.S. Navy Hydrographic Office, Oceanographic Branch,
Marine Survey Division, (May 1956).
17. Brooks, N.H., Ocean Disposal, Summer Institute Notes, Environmental
Engineering and Science Division, Manhattan College, (May 1976).
18. Handbook of Mathematical. Functions With Formulas, Graphs, and
Mathematical Tables, U.S. Dept. of Commerce, National Bureau of
Standards, Applied Math. Series, No. 55, (1964).
19. Hydroscience, Inc., Water Quality Management Planning Methodology
for Hydrographic Modification Activities, Prepared for the Texas
Water Quality Board, (1976).
5-126
-------
20. Vollenweider, R.A., Scientific Fundamentals of the Eutrophication of
Lakes and Flowing Waters—With Particular Reference to Nitrogen and
Phosphorus as a Factor in Eutrophication, Organization for Economic
Cooperation and Development, DAS/CSI/68.27, Paris, France, 1968.
21. Dillon, P.J., and F.H. Rigler, A Test of a Simple Nutrient Budget
Model Predicting the Phosphorus Concentrations in Lake Water,
Canada Fishery Research Board Journal, Vol. 31, 1974.
22. Hydroscience, Inc., Water Quality Management Study, Guadalupe
River Basin, Report No, 43 Mathematical Model of the Guadalupe
River, (August 1971).
23. DiToro, D.M., Photosynthetic Production and Diurnal Dissolved Oxygen,
Summer Institute Notes, Environmental Engineering and Science
Division, Manhattan College, (May 1976).
24. O'Connor, D.J., Lakes, Summer Institute Notes, Environmental
Engineering and Science Division, Manhattan College, (May 1976).
25. Conomos, T.J., Process Affecting Suspended Particulate Matter in the
Columbia River - Effluent System, Ph. D. Thesis, U. of Washington,
(1968).
26. Powell, T. and A. Jussby, "The Estimation of Vertical Eddy Diffusivities
Below the Thermocline in Lakes, Water Resources Research, Vol. 10, pg.
191, 1974.
27. Banks, R.B., Some Features of Wind Action on Shallow Lakes, Journal
of Environmental Engineering Division, ASCE, Vol. 101, Oct. 1975.
28. DiToro, D.M., Line Source Distributions in Two Dimensions:
Applications to Water Quality, Water Resources Research, Vol. 8, No. 6,
Dec. 1972.
5-127
-------
29. DiToro, D.M., Recurrence Relations for First Order Sequential
Reactions in Natural Waters3 Water Resources Research, Vol. 8,
No. 1, Feb. 1972.
5-128
-------
Areawide Assessment Procedures Manual
Chapter 6
Evaluation and Selection
of Control Alternatives
Prepared for
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
-------
TABLE OF CONTENTS
Section Page
LIST OF FIGURES
LIST OF TABLES
6 EVALUATION AND SELECTION OF CONTROL ALTERNATIVES 6-1
6.1 Introduction 6-1
6.2 Water Quality Objectives 6-2
6.3 Load-Reduction Analysis 6-4
6.3.1 Sample Problem 6-6
6.3.2 Dry-Weather Allocation Analysis 6-8
6.3.3 Wet-Weather Load Reductions 6-16
6.3.3.1 Dissolved Oxygen 6-17
6.3.3.2 Total Coliform Organisms 6-18
6.3.3.3 Total Suspended Solids 6-19
6.3.3.4 Nitrogen and Phosphorus 6-19
6.4 Methodology for the Development and
Evaluation of Control Alternatives 6-22
6.4.1 Introduction 6-22
6.4.1.1 Role of the Methodology in
the 208 Planning Process 6-22
6.4.1.2 Monetary Cost 6-24
6.4.1.3 Relative Reliability of the
Performance and Cost
Information • 6-26
6.4.1.4 Organization 6-28
6.4.1.5 Methodology Characteristics 6-29
6.4.2 Methodology 6-30
6.4.2.1 Use of the Methodology 6-30
6.4.2.2 Framework Methodology 6-32
6.4.2.3 Treatment Facility Methodology 6-44
6.4.2.4 Land Application Methodology 6-63
6.4.2.5 Land Management Methodology 6-83
6.4.2.6 Collection System Control Methodology 6-92
6.4.2^7 Storage/Treatment Methodology 6-107
6.4.2.8 Wastewater Reuse Methodology 6-140
6.4.2.9 Impact Area Modification Methodology 6-156
' 6.5.2.10 Regional!zation Methodology 6-175
6.4.2.11 Present-Worth Methodology 6-196
6.4.2.12 Residuals Disposal Methodology 6-205
6.4.2.13 Transportation Costs Methodology 6-218
111
-------
TABLE OF CONTENTS
(continued)
Section Page
6.5 Illustrative Example 6-234
6.5.1 Water Quality Objectives 6-234
6.5.2 Load-Reduction Strategies 6-235
6.5.3 Development and Evaluation of
Control Alternatives 6-237
6.6 References 6-364
IV
-------
LIST OF FIGURES
Figure No. Title Page
6-1 Procedure for Determining Water Quality
Improvement Requirements 6-5
6-2 Methodology for Determining Load Reduction
Requirements 6-10
6-3 Effect of Waste Load Reduction on Dry Weather
Dissolved Oxygen Concentration 6-13
6-4 Alternative Allocations at Two Point Sources:
Hypothetical South River Example 6-15
6-5 Relationship of Chapter 6 Methodology to
208 Planning Process 6-23
6-6 Framework Methodology Overview 6-33
6-7 Framework Methodology: Logic Summary 6-36
6-8 Framework Methodology: Flowchart 6-37
6-9 Treatment Facility Methodology: Logic Summary 6-46
6-10 Treatment Facility Methodology: Flowchart 6-47
6-11 Land Application Methodology: Logic Summary 6-65
6-12 Land Application Methodology: Flowchart 6-66
6-13 Total Land Requirement 6-80
6-14 Land Management Methodology: Logic Summary 6-84
6-15 Land Management Methodology: Flowchart 6-85
6-16 Collection System Control Methodology:
Logic Summary 6-94
6-17 Collection System Control Methodology: Flowchart 6-95
6-18 Storage/Treatment Methodology: Logic Summary 6-108
6-19 Storage/Treatment Methodology: Flowchart 6-109
6-20 Typical Mass Diagram 6-137
v
-------
LIST OF FIGURES
Figure No. Title Page
6-21 Wastewater Reuse Methodology: Logic Summary 6-142
6-22 Wastewater Reuse Methodology: Flowchart 6-143
6-23 Impact Area Modifications Methodology:
Logic Summary 6-158
6-24 Impact Area Modification Methodology:
Flowchart 6-159
6-25 Regional!zation Methodology: Logic Summary 6-178
6-26 Regionalization Methodology: Flowchart 6-179
6-27 Present-Worth Methodology: Logic Summary 6-200
6-28 Present-Worth Methodology: Flowchart 6-201
6-29 Residuals Disposal Methodology: Logic Summary 6-206
6-30 Residuals Disposal Methodology: Flowchart 6-207
6-31 Transportation Cost Methodology: Logic Summary 6-219
6-32 Transportation Cost Methodology: Flowchart 6-220
6-33 Size of Circular Drain Flowing Full 6-232
VI
-------
LIST OF TABLES
Table No. . Title Page
6-1 South River Dissolved Oxygen Objectives 6-7
6-2 Hypothetical South River Water Quality Summary
(20 Year Projections) 6-9
6-3 Framework Methodology Worksheet 6-40
6-4 Treatment Facility Methodology Worksheet 6-51
6-5 Land Application Methodology Worksheet 6-69
6-6 Land Management Methodology Worksheet . 6-87
6-7 Listing of Land Management Control Alternatives
Applicable to Different Land Uses and Land
Use Activities 6-91
6-8 Collection System Control Methodology Worksheet 6-97
6-9 Storage/Treatment Methodology Worksheet 6-111
6-10 Wet-Weather Flow Storage/Treatment Control Options 6-129
6-11 Summary of Concentration Reducing Treatment
Alternatives for On-Site Overflow Treatment Devices 6-132
6-12 Wastewater Reuse Methodology Worksheet ' 6-146
6-13 Potential Customers and Applications for Wastewater
Reuse . 6-154
6-14 Impact Area Modification Methodology Worksheet 6-163
6-15 Regional!zation Methodology Worksheet 6-183
6-16 Present-Worth Methodology Worksheet 6-202
6-17 Residuals Disposal Methodology Worksheet 6-210
6-18 Transportation Cost Methodology Worksheet 6-222
6-19 Load Reduction Strategy Matrix 6-236
6-20 Index to Component Methodologies Used in
Illustrative Example 6-238
VII
-------
CHAPTER 6
EVALUATION AND SELECTION OF CONTROL ALTERNATIVES
6.1 Introduction
Chapter 6 provides an approach for develpping cost-effective water quality
management plans for the 208 planning area. This chapter extends the
analysis procedures of Chapter 5 by presenting guidance for establishing
water quality objectives, for developing strategies for waste load reduc-
tions and allocations, and for developing and evaluating alternatives for
controlling pollutant sources. The discussion presented in this chapter is
intended to provide guidance for these activities. However, where other
techniques for load reduction or cost optimization are available to the 208
planner or engineer, they may be substituted in whole or in part for the
methods presented in Chapter 6.
Water quality objectives are defined from consideration of water quality
standards and water use objectives within the 208 planning area. For certain
parameters, it will be difficult to meet desired water quality objectives
through urban source controls because of the contribution of upstream non-
point source loadings, both within and outside•("background") the 208
planning area. In such cases, the 208 planner will have to investigate
combinations of urban and non-point source control practices which achieve
water quality objectives.
Techniques for developing rational load-reduction strategies in the 208
planning area are presented. These include controls for both dry- and wet-
weather water quality problems, through combinations of municipal and in-
dustrial point source controls and storm water controls. Methods are
presented for determining the levels of control required at each source in
order to attain the relevant water quality objectives.
A methodology is provided for developing and evaluating methods for con-
trolling individual pollutant sources in a 208 planning area. For purposes
of this manual, these methods will be referred to as control alternatives.
Examples of control alternatives are: an upgraded wastewater treatment plant
6-1
-------
to handle a point source problem; a storage basin and treatment unit to
reduce loadings from combined sewer overflows; and a street-sweeping pro-
gram to reduce runoff loadings from urbanized areas. (Although not dis-
cussed in detail, control techniques for non-urban sources are mentioned
in Chapter 4.)
In developing methods of control for wastewater sources, the capability of
various control alternatives to achieve specified performance requirements
is considered. Performance requirements are stated in terms of-.percentage
reductions of wastewater source loadings necessary to achieve the identified
water quality objectives for the receiving water. Alternative combinations
of percentage load reductions from the various sources are developed through
the water quality impact analysis procedures in Chapter 5. These alterna-
tive combinations are referred to as load-reduction strategies. Control
alternatives which meet the performance requirements stated in the load-
reduction strategies are then evaluated to determine the monetary cost of
implementing the alternatives.
The monetary cost of control alternatives is only one of the factors upon
which a final selection of an alternative is based. Other important factors
include: technical reliability; economic, social and environmental impact;
implementation feasibility; and public acceptability. In this manual,
however, the evaluation of alternatives is based only on monetary cost; the
other considerations, and the final selection of control alternatives, are
beyond the scope of this manual. Other EPA 208 guidance documents
address the consideration of other factors needed to determine the control
alternatives most desirable from an economic, environmental, and social
point of view.
6.2 Water Quality Objectives
Water quality standards are the water quality objectives most frequently
utilized in wastewater management programs. State agencies establish
standards to satisfy State and Federal water quality objectives. These
standards are generally based on scientific or empirical evidence that
indicate enhancement of water uses when water quality is within prescribed
limits. Information regarding local water quality standards can be ob-
6-2
-------
tained from the State water quality agencies listed in Table 2-7 (pg. 2-43).
Standards are established to achieve objectives which include but are not
limited to:
1. Protection of public health where waters are to be used for recrea-
tion, public water supply, or commercial harvesting of fin and
shell fish.
2. Protection of the integrity and diversity of the aquatic and marine
biology, including valuable commercial and sport fisheries.
3. Insurance of safety to recreational and commercial navigation.
4. Protection of industrial and agricultural water supply.
5. Maintenance of publicly acceptable levels of aesthetic water
quality.
In general, the 208 planner should consider water quality standards specific
to the planning area as the minimum acceptable water quality objectives.
In certain cases, there are no water quality standards for variables which
are at problem levels in a specific study area. For example, local standards
might not prescribe maximum levels of nitrogen and phosphorus to protect
against nuisance algal blooms. In these instances, the 208 planner should
develop target levels of water quality parameters that will insure a desira-
ble level of water quality protection in the study area.
One basis for defining water quality objectives not specifically dealt with
in existing standards is contained in Chapter 2 — Tables 2-22 (pg. 2-100),
2-23 (pg. 2-104), 2-24 (pg. 2-107), and 2-25 (pg. 2-111). These tables,
however, are presented for guidance purposes only and should be modified to
reflect local experience. Additional information which will prove to be
valuable in setting water quality objectives in the absence of specific
standards is contained in reference (1).
Finally, there will be cases where water quality contravenes standards or
other water quality objectives are attributable to upstream effects which
are either outside of the planning agencies jurisdiction or are uncontrolla-
ble using present technology. These cases should be addressed by assigning
6-3
-------
reasonable objectives which involve consideration of opportunities to meet
water quality goals at some future time if upstream controls can be im-
plemented, and which recognize the practical water use benefits of partial
control of existing problems.
6.3 Load-Reduction Analysis
An overall aim of water quality analysis in a 208 plan is to describe waste-
load reductions which result in compliance with water quality objectives.
This aim is achieved through a waste-load allocation analysis which specifies
alternative combinations of allowable loads to satisfy water quality ob-
jectives. This section provides a methodology for development of the required
/
load-reduction strategies.
The procedure for identifying the needs for water quality improvement
(outlined in Figure 6-1) summarizes many of the analyses made in Chapter 5
and provides the receiving-water-oriented basis for making allocations for
waste-load reduction. The methods of Chapters 2, 3, and 5 normally precede
the load-reduction strategy. In particular, the analysis methods of
Chapter 2 provide an initial assessment of water quality problems and their
associated loads. More detailed loads are then generated in Chapter 3 and
applied in detailed water quality analyses using methods presented in
Chapter 5. Chapter 6 then provides a systematic approach to developing
load-reduction strategies to achieve water quality objectives. The method-
ology is described briefly as follows.
Projections are developed for each relevant water quality constituent for
selected river-flow conditions (Section 2.7, pg. 2-97). The summer low
flow (normally described by the 7-consecutive-day/once-in-ten-year low
flow) is usually considered the critical'case for analyzing dissolved
oxygen concentrations, as well as nutrients and other point source pol-
lutants from municipal and industrial sources, and should be examined first
(Section 2.7.1.3, pg. 2-101). Storm-related problems are then examined
during mean or design-storm conditions (Section 2.7.1.2, pg. 2-101).
Pollutants which have longer-term impacts are analyzed on a long-term
average basis (Section 2.7.3, pg. 2-107).
6-4
-------
IDENTIFY/QUANTIFY
POLLUTANT SOURCES
(Chapters 3 § 4)
DEVELOP WATER QUALITY
(EXISTING/PROJECTED)
DURING . . .
T
Summer Low Flow
Dissolved Oxygen
Nutrients
Total Coliforms
Others
Storm Periods
Dissolved Oxygen
Total Coliforms
Total Suspended Solids
Others
Long Term
Nutrients
Dissolved Solids
Others
(Chapters 2
-------
Each of these analyses is employed in identifying water quality impacts of
the waste loads at critical locations in the stream. The results are then
used in determining the degree to which present and projected loads con-
tribute to water quality problems, and, furthermore, the degree of load
reduction required to meet water quality goals. The final element of the
allocation analysis is a stepwise procedure v/hich develops acceptable load-
reduction strategies.
Various water quality problems in the hypothetical South River are identified
and analyzed in Chapter 5. In Chapter 6, combinations of point source, urban
non-point source, storm sewer and combined sewer load reductions necessary
to meet water quality objectives are identified, and control alternatives to
improve water quality to desired levels are analyzed.
6.3.1 Sample Problem
The objectives used for the hypothetical South River are presented in
Table 6-1. Water quality standards set the objective levels for dissolved
oxygen, while objectives for other variables are defined in the 208 planning
process from consideration of background water quality and site-specific
water uses. The Dissolved Oxygen (D.O.) standard indicates that the D.O.
concentration should be above 5 mg/1 from M.P. 0 to M.P. 20, and ab'ove 4 mg/1
from M.P. 20 to M.P. 35. To evaluate this objective effectively, analyses
are demonstrated in Chapter 5. for low-flow conditions and for conditions
during the "average" storm. Figures 5-10 (pg. 5-41) and 5-11 (pg. 5-42)
indicate that the D.O. standards are currently violated under these con-
ditions.
Water quality objectives are also developed for total coliform organisms,
total suspended solids, total nitrogen, and total phosphorus. The objectives
may still result in problematic conditions, but they appear to be reasonable
as initial objectives due to the current level of pollutants from upstream
non-point and background sources. The objectives for total coliform
organisms and for total suspended solids are defined in terms of the con-
centration during the average storm, while the objectives for nitrogen and
phosphorus are defined in terms of the average (long-term) summer con-
centration (including storm and non-storm periods) because of the longer
6-6
-------
TABLE 6-1
SOUTH RIVER
DISSOLVED OXYGEN OBJECTIVES
1.
2.
Dissolved Oxygen - 1
(DO-1)
Dissolved Oxygen - 2
(DO-2)
Dissolved oxygen minimum of 5 mg/1
from MP 0 to MP 20 and Dissolved Oxygen
minimum of 4 mg/1 from MP 20 to MP 35 during
7 day-10 year low flow
Dissolved oxygen of 5 mg/1 from MP 20 and
Dissolved oxygen minimum of 4 mg/1 from MP
20 to MP 35 during mean storm.
Goals For Other Water Quality Variables
Total Coliform Organisms - 1
(TC-1)
Total Suspended Solids - 1
(TSS-1) •
Nitrogen - 1
(N-l)
Phosphorus - 1
(P-l)
Total Coliform Organisms not to exceed
5,000 MPN/100 ml during mean storm
Total suspended solids not to exceed
200 mg/1 during mean storm
Average total Nitrogen not to exceed
2.5 mg/1 as a long term summer average
Average total Phosphorus not to exceed
0.4 mg/1 as a long term summer average
6-7
-------
temporal scale of impacts associated with nutrients. The rationale for de-
scribing these as critical time periods for each water quality variable are
described in Chapter 2 and summarized in Chapter 5 (pg. 5-43).
The water quality constituents of concern in the hypothetical South River
and the locations of the maximum concentrations are summarized in Table 6-2.
Preliminary estimates of the load reductions required to meet water quality
objectives at these locations are also summarized in Table 6-2. In this
regard, the contributions to water quality problems attributable to each
source and the total reductions required to meet the water quality objectives
are estimated in Table 6-2.
Using this data, the allocation proceeds through the steps outlined in
Figure 6-2.. Section (a) of the diagram describes the procedures for de-
veloping waste-load allocations for dry-weather conditions, -and section
(b) describes the procedures for wet-weather conditions. The steps in this
dry-weather allocation analysis are described and illustrated sequentially
in the following paragraphs.
6.3.2 Dry-Weather Allocation Analysis
Figure 5-11(a) (pg. 5-42) indicates two critical locations at which Dissolved
Oxygen concentration is in violation of water quality standards: Milepoints
19.5 and 23.5. The unit response presented in Figure 5-ll(b) suggests that
one alternative which could satisfy the water quality standards while main-
taining a reserve of 0.5 mg/1 of Dissolved Oxygen at the critical location
is treatment at STP #2 alone. This conclusion is developed as follows:
Critical deficit at M.P. 23.5: 8.1 mg/1
Allowable deficit at M.P. 23.5: 8.17 mg/1 (saturation)
-4.00 mg/1 (standard)
4.17 mg/1
-0.50 mg/1 (reserve)
3.67 mg/1 (allowable)
6-8
-------
o»
TABLE 6-2
HYPOTHETICAL SOUTH RIVER WATER QUALITY SUMMARY
(20 YEAR PROJECTIONS)
Constituent:
Flow Condition:
Location of Peak
Concentration
(Milepoint)
Components of
Impact at Critical
.'xication
a) STP I
b) STP II
c) Industry
d) Storm Sewer
Runoff
e) Combined Sewer
Overflow
f) Other Background
Loads
g) Total
Criteria/Ob j ective
Preliminary Estimate
of Required Reduction
Dissolved
Low Flow
19.5
(Critical
Location
in Upper
Reach)
(mg/D
-
5.25
-
-
-
0.05
5.30
DO=S
Cs=8.17
Allowable
DEF=3.17
2.13
+0.50 (Reserve)
2763
Oxygen Deficit
Low Flow
23
(Critical
Location
in Lower
Reach)
(mg/D
3.10
5.00
-
-
-
0.05
8.15
D0=4.0
Cs=8.17
Allowable
DEF=4.17
3.98
+0.50 (Reserve)
4748"
Mean
Summer Flow
33
(mg/D
0.55
1.00
0.15
1.10
2.00
0.50
5.30
D0=4 . 00
Cs=8.17
Allowable
DEF=4.17
1.13
+0.50 (Reserve)
T76Y
Total Coliform
Mean
Summer Flow
19
MPN/100 ml
-
350
-
53,000
1,150,000
330
1,204,000
5,000'
1,199,000
(99.6%)
Total
Suspended
Solids
Mean
Summer Flow
15
Cmg/l)
-
-
-
260
-
110
370
200
170
(46%)
Total
Nitrogen
Average
Summer Flow
24
(mg-N/1)
0.90
1.60
-
-
-
1.45
3.95
2.50
1.45
(37%)
Total
Phosphorus
Average
Summer Flow
24
(mg-P/1)
0.45
0.80
-
-
-
0.15
1.40
0.40
1.90
(72%)
-------
(oX
PICK LEAST
COST ALTERNATIVE
YES-
FOR EACH REI.RVANT WATIiR QUALITY CONSTITUUNT
IDENTIFY COMBINATIONS OF SOURCE REDUCTIONS T1IAT GIVE
REQUIRED TOTAI, REDUCTIONS IN RECEIVING WATER
MEET REQUIRED REDUCTIONS
DURING SUMMER LOW FLOW?
-YES •
NO
TECHNOLOGICALLY
FEASIBLE
ALTERNATIVE?
CONTINUOUS NON-POINT
SOURCE REDUCTION
[EMPHASIZE REDUCTIONS AT .ONE LOCATION
EMPHASIZE REDUCTION OF ONE COMPONENT OF
RESPONSE (I.E., NITROGENOUS FOR DO DEF)
LOOK AT COMBINATION OF LOCATION AND
COMPONENT.REDUCTIONS
PICK LEAST
COST ALTERNATIVE
NO
MEET REQUIRED REDUCTIONS
DURING STORM PERIODS?
I
NO
-YES-
CONTINUOUS POINT SOURCE
REDUCTIONS
INTERMITTENT SOURCE
CONTROL
T
[EMPHASIZE REDUCTIONS TO INTERMITTENT SOURCESj
t
I
CONTINUOUS NON-POINT
SOURCE REDUCTIONS
YES-
| COMBINED SEWER|
STORM SEWER]
EMPHASIZE FURTHER CONTINUOUS POINT OR
NON-POINT SOURCE REDUCTIONS
LOOK AT COMBINATIONS OF INTERMITTENT AND CONTINUOUS
POINT OR NON-POINT SOURCE REDUCTIONS
\ MEET REQUIRED REDUCTION OVER LONG TERM*
-•-YES-
FIGURE 6-2
METHODOLOGY FOR DETERMINING
LOAD REDUCTION REQUIREMENTS
6-10
-------
The total deficit due to STP #1 and the industry is 3.3 mg/1 at Milepoint
23.5. Thus the allowable deficit due to STP #2 at Milepoint 23.5 is:
Allowable Total Deficit (M.P. 23.5) 3.67 mg/1
Deficit (other sources) 3.30 mg/1
Allowable STP #2 deficit (M.P. 23.5 0.37 mg/1
Thus if the deficit from the STP #2 discharge can be reduced to 0.37 mg/1,
\
the D.O. water quality standards can be maintained. The required additional
UOD (Ultimate Oxygen Demand) reduction in the secondary effluent is computed
as follows:
Deficit due to STP #2 (M.P. 23.5) 8.10 mg/1 (total deficit)
3.10 mg/1 (STP #1 Deficit)
5.00 mg/1 (STP #2 Deficit)
Present reduction required = u nl '— =92.6 percent UOD removal
o • UU
The required reduction must be accomplished through a combination of carbon-
aceous and nitrogenous BOD removal which satisfies the 92.6 percent UOD re-
duction criteria.
Clearly, other combinations of treatment at STP #1 and STP #2 can also be-
considered. For example, the minimum treatment above secondary treatment
at STP #2 which satisfies the water quality standards considers reduction in
the UOD load at that plant such that compliance with the standard is achieved
at Milepoint 19.5 (the critical point in the STP #2 D.O. deficit profile).
The computation proceeds as follows:
Total deficit at M.P. 19.5 5.3 mg/1
Allowable deficit at M.P. 19.5 8.17 mg/1 (saturation)
-5.00 mg/1 (standard)
3.17 mg/1
-0.50 mg/1 (reserve)
2.67 mg/1 (allowable)
The percent UOD reduction is computed as:
Total deficit due to STP #2 (M.P. 19.5) 5.3 mg/1
O (L*7
Percent reduction required = ' Q = 50 percent UOD removal
6-11
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Therefore, the minimum additional treatment of the secondary discharge re-
quired at STP #2 is 50 percent reduction of UOD, which can be accomplished
through various combinations of carbonaceous and nitrogenous BOD removal.
The resulting D.O. profile in the South River is illustrated in Figure 6-3.
The figure indicates the need for additional removals of UOD at STP #2.
Computation of this load reduction is accomplished as follows:
Deficit due to STP #1 (M.P. 23.5) 3.3 mg/1
Allowable deficit at M.P. 23.5 8.17 mg/1' (saturation)
-4.00 mg/1 (standard)
4.17 mg/1
-0.50 mg/1 (reserve)
3.67 mg/1 (allowable)
A 50 percent reduction in UOD at STP #2 reduces the deficit due to STP #2
at Milepoint 23.5 from 4.1 mg/1 to 2.05 mg/1 (0.5 x 4.1 = 2.05). The total
deficit at M.P. 23.5 is calculated to be:
Deficit due to STP #1 (M.P. 23.5) 3.30 mg/1 (Figure 5-10)
Deficit due to STP #2 (M.P. 23.5) 2.05_ mg/1 (above)
Total deficit (M.P. 23.5) 5.35 mg/1
and the load reduction at STP #1 is:
Total deficit (M.P. 23.5) 5.35 mg/1
Allowable deficit (M.P. 23.5 5.67 mg/1
Difference 1.68 mg/1
Percent reduction at STP #1 1.68 = 51% UOD removal
3.30
The resulting D.Q. profile based on SO percent UQD removal at STP #2 and 51
percent UOD removal at STP #1 is Shown in Figure 6-3. Note that the final
allocation results in a 0.5 mg/1 reserve to allow for modeling uncertainties
and for future growth. The selection of a reserve capacity is normally
based on a local knowledge of future growth projections and on an under-
standing of uncertainties in the water quality modeling framework. A
reserve of 0.5-1.0 mg/1 is typical.
6-12
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UJ
X
o
Q
UJ
O
V)
V)
12
10
8
6
(a
0-5OCFS(7DAY-IO YEAR FLOW)
TEMPERATURE*Z5°C
D.O. STANDARD
(o) WITH 50% REMOVAL
AT STA. NO.Z
(b)WITH ADDITIONAL 51%
REMOVAL AT STP NO. I
1 I
10 15 20 25
MILES BELOW ROUTE 80 BRIDGE
30
35
en
E
o
u.
UJ
o
UJ
x
o
o
U)
o
V)
to
a
DROUGHT FLOW
NO DISTRIBUTED SOURCES
DEFICIT RESPONSE WITH
50%UOD REDUCTION AT STP NO. 2,
51% UOD REDUCTION AT STP NO. I.
BACKGROUND
UPSTREAM
MILES BELOW ROUTE 80 BRIDGE
SOUTH RIVER
FIGURE 6-3
EFFECT OF WASTE LOAD REDUCTION ON DRY WEATHER
DISSOLVED OXYGEN CONCENTRATION
6-13
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The user should be aware that EPA' guidelines do not provide specific recom-
mendations for how much reserve capacity (if any) should be included in
wasteload allocation for future growth (whether for possible industrial
activities whose wastewaters will not be treated by municipal facilities or
for "ultimate development"). In many cases, there will be strong pressure
for full utilization of stream assimilative capacity in order to hol-d down
treatment costs. In stream segments where assimilative capacity is already
or expected to be constrained during the planning period, local communities
will be faced with difficult wasteload allocation decisions. Such decisions
should be supported by local growth policies, other local policies, and
related regulatory programs (i.e., local ordinances and pricing structures
designed to encourage flow reduction or pretreatment). While discussion of
these non-structural management techniques is beyond the scope of this
manual, the user should be cognizant of their potential application.
The conclusions that can be drawn from the analysis to this point are:
1. Compliance with D.O. water quality standards during critical-
flow, dry-weather conditions requires treatment at least at
STP #2. The upper limit on that treatment is an additional
92.6 percent UOD removal. The lower limit on treatment at
STP #2 requires an additional 50.percent UOD removal at STP
#2 and an additional 51 percent UOD removal at STP #1.
2. There is a continuum of allocations which can be developed
for both plants to attain additional UOD reductions of be-
tween 50 percent and 92.6 percent at STP #2 and between 51
.percent and 0 percent at STP #1.
5. Additional UOD load reductions at either plant can be accom-
plished through carbonaceous and/or nitrogenous removal.
At this point, the analyst is faced with the problem of determining the most
cost-effective treatment option which effects compliance with water quality
objectives. A convenient way of viewing the options is presented in Figure
6-4, which displays combinations of UOD removals at the two treatment plants
which result in satisfactory water quality. For example, 75 percent UOD re-
moval at STP #2 and 20 percent removal at STP #1 also results in compliance
6-14
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100
*
W 90
O
2
0. 60
H
I- 70
<
t
60
o
s
UJ
o:
cj
q
ri
Ul
o
a:
50
30
20
10
O1
_L
J_
I
J_
_L
I
I
I
10 20 30 40 50 6O 70 80 90
PERCENT U.O.D. REMOVAL AT STP NO.I*
100
NO re:
* PERCENT UOD REDUCTIONS REPRESENT
ADDITIONAL REDUCTIONS BEYOND PRESENT TREATMENT.
FIGURE 6-4
ALTERNATIVE ALLOCATIONS AT TWO POINT SOURCES
HYPOTHETICAL SOUTH RIVER EXAMPLE
6-15
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with the water quality standards under critical-flow, dry-weather conditions.
The relationship in Figure 6-4 is not necessarily linear and must be de-
termined by computing several independent allocations. Also, this formu-
lation is not appropriate where the carbonaceous and nitrogenous BOD decay
rates are significantly different. Similar allocation procedures apply to
other water quality variables which contribute to dry-weather water quality
problems.
6.3.3 Wet-Weather Load Reductions
Once the dry weather allocations have been completed for each of those water
quality parameters for which problems are projected to exist, the analysis
proceeds to wet-weather load allocations. The specific techniques presented
here are limited to wet-weather allocations based on treatment of a design-
storm load only. The reason for this restriction is that the state-of-the-
art technology regarding the effect of storm-water-control structures on the
statistical properties of the storm load (probability density function and
coefficient of variation) is limited at present to statements regarding the
mean-load from the control device. As more information regarding the behavioi
of these devices is developed from prototype units, present theories regarding
the relationships between the 'input and output storm-load statistics of con-
trol devices may be verified or modified-such that full characterization of
the frequency distribution of treated storm loads can be made.
In practical terms, this places limitations on the use of a statistical ap-
proach for wet-weather allocations until additional information on the
behavior of storm treatment and control devices becomes available, as
previously described. To further illustrate this limitation, consider
Figure 5-10 (pg.5-41). The figure shows that the mean storm results in a
minimum D.O. deficit of 2.8 mg/1 at Milepoint 34; the standard is 4.0 mg/1
at this point. Therefore, the load reduction developed in this section
considers treatment of the mean load such that the minimum D.O. concentration
during the mean storm is raised from 2.8 mg/1 to 4.0 mg/1. Since further
evaluations using the probability density function or the variability of the
treated load cannot be made, the frequency-distribution of water quality for
treated loads cannot be defined as it was for untreated loads in Chapter 5.
6-16
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It should be noted, however, that if one knows the probability density
function and the variability (coefficient of variation) of the treated load,
the frequency distribution of water quality responses due to treated loads
could be calculated in exactly the same manner as presented in Chapter 5 for
untreated storm loads. Two ways to overcome this problem are under de-
velopment. First, theoretical studies of treatment-device effect on the
probability density function, and of variability around a treated mean storm
load are now in the research stage, and possibly will be developed for
application purposes within a year or two. Second, the statistical properties
of the treated storm load may be empirically determined through the use of
treatment-device simulators on a long sequence of treated storm loads.
The output from such studies can be used to develop the statistics of treated
storm water loads for inclusion in a water quality analysis such as that pre-
sented in Chapter 5. When such work is completed, the planner will be able
to determine storm treatment requirements necessary to prevent violation of
water quality standards a given percentage of the time. Conversely, if a
storm control device is planned for an area, this method of analysis will
permit estimates of the reduced frequency with which standards will be
contravened with the control in operation. In subsequent sections of
Chapter 6, a more generalized load-reduction methodology, which considers
procedures for evaluating various storm water control options, is developed.
6.3.3.1 Dissolved Oxygen
Table 6-2 indicates that the critical location for Dissolved Oxygen during
the mean storm is at Milepoint 33, where a 1.63 mg/1 reduction in the deficit
is required. A portion of this reduction will be met by the 50 percent UOD
removal at STP #1 and STP #2 necessary to meet objectives during low flow.
The average storm deficit response at Milepoint 33 from STP #1 is 0.50 mg/1,
and from STP #2 it is 1.00 mg/1. The 50 percent reduction, therefore, results
in 0.50 (0.55 + 1.00} = 0.77 mg/1 deficit reduction during the average storm.
An additional reduction of 0.86 mg/1 (1.63-0.77) is required to meet standards
under the average storm condition. The average storm deficit response at
Milepoint 33 from the combined sewer overflow is 2.00 mg/1. An effective
load-reduction plan therefore requires a 43 percent (100 x 0.86/2.00) re-
duction in the combined sewer UOD load for the average storm event.
6-17
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The storm sewer runoff load contributes 1.10 mg/1 of deficit at Milepoint 33
during the average storm. If the storm-related UOD reductions are obtained
equally from the combined and storm sewer loads, a 28 percent (0.86/(2.00 +
1.10)) UOD load reduction is needed at both sources.
/
6.3.3.2 Total Coliform Organisms
Allocation of wet-weather loads of total coliform organisms from the urban
area is developed in a manner similar to that for Ultimate Oxygen Demand
(UOD) allocations. Figure 5-14 indicates that the projected total coliform
concentrations in the South River are dominated by storm water loadings. Two
allocations are developed here to illustrate the load-reduction methodology.
The first emphasizes load reduction at the combined sewer system overflow
points. In this regard, a reduction is required in the storm sewer system
to reduce the peak coliform concentrations in the region between Milepoints
14 and 19 to less than the 5>000 MPN/100 ml storm-period objective. The re-
quired storm sewer reduction is:
Percent Reduction (Storm Sewer) = 140 000 ' =96.4 percent
In addition to the 96.4 percent reduction of the storm sewer load, further
reductions in total coliform loads from the combined sewer system are re-
quired to meet the objective in the region below Milepoint 19. Note that
background and point sources are expected to contribute 800 MPN/100 ml to
the water quality condition; the combined sewers will contribute 1.15 x 10
MPN/100 ml. With the previously indicated reduction in the storm sewer load
of 96.4 percent, that source will contribute about 2,500 MPN/100 ml at Mile-
point 19. The reduction in total coliforms from the combined sewer system is
then computed to be:
n * n J • r^orA d-15 X 1Q6 + 800 + 2,500 - 5,000)
Percent Reduction (CSO) = - ^ J -
1.15 x 10
'Percent Reduction (CSO) = 99.85 percent
An alternative load-reduction strategy that involves equal removals at both
storm and combined sewer systems can also be developed. In this case, the
computation is as follows:
6-18
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CSO Impact (M.P. 19) 1.15 x 106 MPN/100 ml
Storm Sewer Impact (M.P. 19) 70,000 MPN/100 ml
Other Sources (M.P. 19) 800 MPN/100 ml _
Total 1.2208 x 106 MPN/100 ml
Objective (Storm Periods) 5,000 MPN/100 ml
Percent Reduction (1.22 x 106 - 5 x 105) = 99.65 percent
(Storm Periods) 1.22 x 10
Therefore, control of storm-related discharges sufficient to achieve 99.65
percent removal at both storm system discharges and combined sewer system
overflows will also meet the required objective.
6.3.3.3 Total Suspended Solids
The water quality objective for suspended solids concentration during summer
storm periods is 200 mg/1; this reflects the high background concentrations
coming from non-point sources upstream of the urban area. The total back-
ground effect (Figure 5-13, pg. 5-45) is expected to be 185 mg/1 at Milepoint
15. The storm sewer system which contributes the largest single component to
the impact downstream of Milepoint 19 contributes an additional 280 mg/1 at
this point. The load reduction for suspended solids control is therefore
applied to the storm sewer load as follows:
Percent Reduction (SS) = C185 *™° " 200^ =94.6 percent
Similarly, an objective of 250 mg/1 of total suspended solids would require
77 percent removal.
Percent Reduction (SS) = C185 * j*f° " 250^ = 77 percent
280
6.3.3.4 Nitrogen and Phosphorus
The nutrient water quality objectives in the South River study area also re-
flect elevated background concentrations. The objectives are set at 2.50
mg of nitrogen per liter and 6.40 mg of phosphorus per liter. Additional
modeling efforts would normally be required to determine the impact of these
target nutrient levels on phytoplankton productivity and weed growth in down-
stream areas. This would normally involve detailed numerical modeling
analyses of nutrient-phytoplankton-zooplankton interactions and/or weed-
6-19
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growth modeling frameworks. Both are sophisticated analytical procedures that
require specialized tools and personnel thoroughly familiar with the technical
issues involved in this type of modeling.
In the absence of such modeling, objectives are normally set merely to reduce
nutrient levels, thereby reducing the probability of existing or potential
problems. Nutrient reductions are not always required for both macronutrient
species, nitrogen and phosphorus. That is, a limitation of either nutrient
will normally limit the productivity of plant systems in the downstream area.
Cost effectiveness of removing one nutrient preferentially over the' other
normally governs the load-reduction analysis in this case. Therefore, in the
South River example both nutrients are allocated, but only one allocation is
ultimately implemented.
The load reduction for nitrogen can be accomplished by requiring nitrogen re-
moval at one or both plants. Figure 5-11 indicates that, if load reduction is
required at only one plant, the allocation must be total (100 percent) removal
at STP #2 (removal of 100 percent of the nitrogen load at STP #1 would not
accomplish the objective).
Combinations of nutrient removal at both plants, however, are feasible. For
example, equal percent removals at both plants is computed to be 55 percent
removal of total nitrogen, a reasonable treatment level which could be
achieved by some flow splitting in both plants. The allocation is computed
as follows for a critical location (Milepoint 20 in Figure 5-12(a), pg.
5-44):
STP #2 Impact = 1.65 mg N/l
STP #1 Impact = £^9£ mg N/l
Total STP Impact = 2.55 mg N/l
Background Impact = 1.35 mg N/l
Objective = 2.50 mg N/l
Percent Reduction (STP 1 and 2) = C2'55 + *'^ " 2'5Q) = 55 percent
Similarly, the phosphorus reduction required to meet the objective (0.40 mg
of phosphorus per liter) can be computed as follows:
6-20
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STP #2 Impact =0.80
STP #1 Impact = 0.50
Total STP Impact =1.30
Background Impact =0.10
Objective =0.40
Percent Reduction (STP 1 and 2) = C1.50 + 0.10 - 0.40) = ?? percent
J. • oU
The load reduction computed in this manner requires 77 percent phosphorus re-
duction at both treatment plants. An alternative scheme would be to remove
90-95 percent of the phosphorus at one plant, with an additional allocation
to remove the remainder of the phosphorus overload from the other plant.
6-21
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6.4 Methodology for the Development and Evaluation of Control Alternatives
6.4.1 Introduction
6.4.1.1 Role of the Methodology in the 208 Planning Process
This Areawide Assessment Procedures Manual provides guidance only for certain
steps of the 208 planning process. Figure 6-5 illustrates how the Chapter 6
methodology and topics addressed in other chapters in this manual fit into
the overall 208 planning process. The steps of the general 208 planning
process are presented as a flow chart at the left, in approximate order of
their occurrence. The right side of Figure 6-5 lists the specif!' Copies
addressed in this manual, with the horizontal position of each manual topic
in this flow chart corresponding to the -position of the step or steps in the
planning process which the topic represents. .The general planning steps
which have no corresponding topics in the manual are covered by other EPA
guidance documents.
Figure 6-5 also shows the relationships among different parts of this manual.
Chapters 1 through 4 cover problem identification and load assessment, Chapter
5 addresses analysis of the water quality impact of the wastewater loads, and
Chapter 6 presents guidance for three key areas: water quality objectives,
load-reduction strategies, and control alternatives. The selection of water
quality objectives forms the basis for determining the type and degree of
wastewater source control. Various load-reduction strategies for meeting
the objectives are formulated, as explained earlier in this chapter. These
.strategies deal with the number and types of sources to be controlled and
the amount of load reduction to be achieved at each source. Finally, control
alternatives are developed on the basis of performance capabilities, and are
evaluated for their monetary costs. The result is an identification of the
cost of control alternatives which can achieve the desired water quality
obj ectives.
The appendixes to the manual support various chapters, as shown in Figure 6-5.
For example, Appendixes G and H contain performance and cost data for the
development and evaluation of control alternatives, which are covered in
Chapter 6. Specifically, Appendix G contains information on urban non-point
source control alternatives, including land management and collection system
6-22
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FIGURE 6-5
RELATIONSHIP OF CHAPTER 6 METHODOLOGY
TO 208 PLANNING PROCESS
208 PLANNING PROCESS
AREAWIDE ASSESSMENT PROCEDURES MANUAL
Planning
Area
Identification
Goals
and
Objectives
Water Quality
Objectives
(Chapter 6)
Data
Collection/
Inventories
Projections
Data Base Inventory and Problem
Identification (Chapters 1,2)
Waste Load
Assessment
(Chapters 2,3,4)
Planning Guides:
Constraints, Criteria,
Priorities
Analysis
Water Quality
and Land Use
Data Bases
and
Monitoring
(Appendixes B,C,D)
Water
Quality
Impact
Analysis
(Chapter 5)
Alternatives
Development
Models and
Statistical Analysis
(Appendixes A,E)
Waste Load Reduction
Strategies (Chapter 6)
Alternatives
Evaluation/
Refinement
Alternatives Development and
Evaluation Methodology
(Chapter 6)
Point and Non-point
Source Control
Alternatives:
Performance and Costs
(Appendixes G,H)
Alternative
Selection
JL
Program Implementation I
Plan Updating
6-23
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controls. Appendix H contains performance data and cost curves for continuous
and intermittent point source control alternatives, including wastewater and
residuals treatment systems, and wet-weather storage and treatment units.
The appendixes may be used as sources of performance and cost data to
support calculations and alternatives evaluation based on methodologies out-
lined in this chapter. Before applying the methodologies, the user should
study carefully the introductions to the appendixes to understand the
assumptions and design basis upon which the cost curves were developed. Only
certain costs have been specifically included in the cost curves. In order
to develop total cost estimates, the user must add allowances for the factors,
such as engineering design and contingencies.
Of course, sources of cost information other than Appendixes G and H may be
utilized for any of the necessary determinations. Here again, the user must
be careful to investigate which factors have been included in the estimate
being used so that it will be consistent with other cost information.
In the Chapter 6 methodology, the performance data are used to determine the
technological feasibility of a particular control alternative and the size or
number of control devices necessary to achieve the required load reduction.
The cost curves or equivalent sources are then utilized to determine the
associated monetary cost.
6.4.1.2 Monetary Cost
The Federal Water Pollution Control Act Amendments of 1972 (P.L. 92-500)
specify cost-effectiveness as the principal .criterion for the planning and
development of wastewater management programs as those programs relate to
municipal treatment works and to the control of combined sewer overflows and
storm sewer discharges. EPA has defined cost-effectiveness analysis as a
systematic comparison of alternatives to identify the solution which minimizes
total costs to society over a defined planning period to meet given goals and
objectives in a reliable manner. Section 208(b)(2)(e) specifies that the
plan, in determining the total cost to society, should document the economic,
social, and environmental costs as well as the capital, operating, admin-
istrative, and maintenance costs of implementing the control alternatives.
These latter costs can usually be quantified in monetary terns, but the
6-24
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economic, social, and environmental costs are more difficult to quantify
and may require description and evaluation using more subjective techniques.
Monetary costs tend to receive most of the planner's attention in cost-
effectiveness analysis. Also, decision-makers tend to be oriented toward
cash outlays and toward the financial aspects of 208 planning implementation;
in fact, many public-advisors and government officials are not at all
accustomed to dealing with and making decisions based on non-monetary cost
factors. Nevertheless, the 208 engineer or planner has the responsibility
to identify and present all significant costs (both monetary and non-monetary)
when considering control alternatives.
Other 208 guidance documents provide guidelines for social, economic, and
environmental impacts and cost analysis. This manual deals only with the
determination of the monetary cost associated with implementing the various
techniques presented. However, this should not be construed, to mean that the
user should orient his cost-effectiveness analysis so closely to monetary
costs that the other cost considerations are overlooked or obscured. Also,
alternatives should not be eliminated from further evaluation solely because
of a high monetary cost relative to other alternatives. The consideration
of non-monetary or non-quantifiable factors may result in a low monetary-cost
alternative actually having a high total cost to society. Conversely,
further analysis may render an alternative with high monetary cost very
attractive because of public sensitivities or other localized factors.
For these reasons, the Chapter 6 methodology is not intended to serve as the
only guide to the user for selecting or eliminating a control alternative from
further consideration.
In some cases, pre-screening of specific applications of a control alternative
will be made on the basis of least monetary cost. For example, the most
promising (least-cost) sites among a number of potential sites will be chosen
in the initial evaluation of land application as a feasible control alterna-
tive. If the land application approach is still attractive after other
factors have been evaluated, a more detailed analysis procedure may be 'em-
ployed to assure that the most cost-effective land application sites have
been identified. As far as this methodology is concerned, all control
6-25
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alternatives which are found to be feasible from a performance point of view
will be evaluated for monetary cost, unless the user chooses not to do so for
other reasons.
6.4.1.3 Relative Reliability of Performance and
Cost information
Monetary-cost comparisons should not be the sole basis for selecting control
alternatives, but at some point in the selection process the relative costs
of various alternatives must be considered. Therefore, it is very important
for the engineer or planner to understand the reliability of the information
upon which the cost figures are based.
The reliability of performance data must also be considered, because this
type of information frequently is the basis for determining the size of
treatment units or other control devices needed for a particular control
alternative. This section covers the use of the performance and cost
information of Appendixes G and H, and provides a method for assuring adequate
consideration of the relative reliability of the various inputs of informa-
tion (performance and cost) involved in comparison of.the cost of various
control alternatives.
The performance data and cost information in Appendixes G and H are utilized
to determine the monetary cost of feasible control alternatives for address-
ing water quality problems in 208 planning areas. Performance data for a
particular control alternative are compared to a required standard to assess
the alternative's capability to meet the standard. Then the monetary costs-
of those alternatives which meet the performance requirements are determined
by utilizing the cost curves. Since performance and cost information for
one alternative may be based on much more extensive data and experience than
the information for another alternative, the reliability -of both the cost in-
formation and the performance information should be taken into account when
considering relative cost and performance capabilities.
The reliability of information is especially important in developing,
evaluating, and selecting control alternatives for areawide water quality
management, because there are highly varying degrees of experience with the
various control alternatives. For example, an abundance of cost figures and
6-26
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estimates are available to substantiate performance and cost curves for an
activated sludge treatment plant. Less data and experience are available
to substantiate performance and cost relationships for street sweeping as
an alternative in control of pollution from urban runoff. Even less data
and experience are available to substantiate performance and cost estimates
for various land management alternatives such as zoning. Although each of
these three alternatives is known to be effective in reducing pollutant
levels, determination of the best combination will require careful delibera-
tion, good judgment, and full recognition of the reliability of each type of
information at the time the decision is made.
The concept of "relative reliability" is presented here to aid the user of
this manual in comparing the monetary cost of control alternatives. Five
levels of relative reliability are used to identify the nature and extent
of the experience and data upon which the cost and performance information
is based:
• Level A indicates estimates based on detailed breakdowns of all
pertinent cost elements and is supported by detailed engineering data.
This level of reliability is always based on site-specific information.
The relative reliability of information in this level is +_ 15%.
For example, facilities-planning estimates (Section 201 of P.L.
92-500) represent Level A information reliability.
• Level B indicates that the data and experience on a particular
control alternative are sufficient only to establish a relationship,
as expressed by a table of data or a single curve or family of
curves. The relative reliability of information at this level
is +_ 30%. For example, general cost curves such as the wastewater
treatment systems curves and process curves presented in Appendix H
represent Level B information reliability.
• Level C indicates that the data and experience are sufficient only to
establish a range of values for cost or performance. The relative
reliability of information at this level is +_ 50%. For example, street
sweeping estimates, such as those in Appendix G, represent Level C
information reliability.
6-27
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• Level D indicates that the data and experience are sufficient only to
establish the relative order of magnitude of the cost and performance
characteristics.
• Level E indicates that the data or experience is insufficient to
establish any level of cost or performance estimate, or that site-
specific factors are so critical to the performance and cost that a
general estimate should not be made.
This manual does not present guidelines on the application of the relative
reliability concept for particular situations. Rather, the application by
the user will be a function of the control alternatives that are being
compared, the closeness of the cost or performance estimates, the background
of the user, the consequences of error, and other factors.
The "relative reliability" concept is introduced to emphasize to the user that
comparisons of cost or performance estimates prepared using this manual are
only as reliable as the lowest level of reliability assigned to the control
alternatives being considered. The concept is particularly well suited to
compare more traditional engineering approaches to load reduction with
"emerging" non-structural control techniques whose costs and relative
effectiveness have not been satisfactorly evaluated or sufficiently
documented.
6.4.1.4 Organization
The methodology consists of: 1) a framework methodology for directing the
user through the methodology operations; and 2) a number of component method-
ologies for investigating specific control alternatives. The framework
methodology guides the user through the entire process of developing and
evaluating control alternatives, including the determination of one or more
feasible alternatives for -controlling each source under each load-reduction
strategy. The component methodologies are designed to facilitate the de-
termination of the feasibility and monetary cost of implementing a particular
control alternative for a wastewater source of concern.
Both the framework and the components are presented in Section 6.4.2. -An ex-
ample illustrating the use of the methodology in a hypothetical planning area
6-28
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is presented in Section 6.5 as a further aid to the user.
6.4.1.5 Methodology Characteristics
In order that the user may better understand and use this methodology, certain
characteristics of the methodology are discussed in the following paragraphs.
The methodology is a logical approach to addressing various pollution
problems. It shows the relationship between various types of pollution
problems and feasible control alternatives, and illustrates a logical
sequence for addressing the problems.
The methodology involves a level of detail which is consistent with the 208
level of analysis. Assumptions and simplifications are made throughout the
methodology to facilitate the development of cost estimates with a minimum
of site-specific data gathering or use of sophisticated analytical tech-
niques and calculations.
The calculations, engineering assumptions, and judgments used in the method-
ology allow the user to arrive at a particular determination or answer.
The methods presented herein should not be interpreted as the only possible
approach. New data, additional information, or advanced techniques may be
substituted at any point for those suggested in the methodology. The function
of the methodology is to illustrate the interfacing and logical timing of de-
terminations, rather than to present a rigid or all inclusive list of control
alternatives. The user should not hesitate-to use other data or techniques
if he has the necessary information and expertise.
The methodology has been designed for ease of understanding and application.
Both the framework methodology and the component methodologies include:
1) logic summary, 2) a detailed operations flowchart, 3) worksheets, and
4) notes on specific operations in order to facilitate understanding and use.
Also, the methodology is designed so that the major determinations can be
accomplished by hand calculations, with a minimal requirement for outside
data or special expertise.
The methodology is comprehensive in that it deals with point (continuous and
intermittent) and non-point sources of pollution, and with structural and
non-structural alternatives for controlling these sources. However, it does
6-29
-------
not provide all the detailed analytical techniques or background information
needed to analyze all aspects of the implementation of a specific control
alternative, such as information on funding, siting, or staging of facilities,
and other detailed engineering determinations. These considerations can be
explored separately if they are found to be critical to the development and
evaluation of alternatives. However, the methodology does suggest where the
considerations should be injected into the analysis and how they relate to
other parts.
The methodology provides for several levels of analysis. Depending on the
complexity of the planning area (i.e., the numbers and types of sources, the
degree and complexity of water quality problems, the size of the area, popu-
lation, etc.), the methodology can be used to identify the most effective
general approaches to the problems, or can be used to perform a more detailed
evaluation of individual sources for a specific water quality problem. For
example, if a number of point sources are in close proximity, their waste-
water loads may be aggregated to simplify both the water quality impact
analysis and the investigation of control alternatives. The methodology may
be used to investigate the necessity for an improvement in the level of
treatment of the aggregated load or the elimination of that load by appli-
cation to the land, or other appropriate alternatives. In addition, the
methodology can be used to refine this analysis by segregating loads and
investigating the treatment prpcess alternatives at a particular site, when
this is of interest. Thus, the methodology is flexible in that the level of
analysis can be adjusted to the level of complexity of the area and to the
particular problems or control alternatives of interest.
6.4.2 Methodology
6.4.2.1 Use of the Methodology
Content
The presentation of the framework and component methodologies includes:
1. Introduction - relates in general terms the objectives of the pro-
cedure or the control alternative.
6-30
-------
2. Logic Summary - summarizes the basic logic on which the procedure
is based, by listing the major steps involved.
3. Flowchart - presents the detailed steps involved in carrying out
the procedure. (These steps are expansions of steps listed in the
foregoing logic summary and include references to the Worksheets.)
4. Worksheet - suggests one of. several methods for recording the de-
terminations, calculations, comparisons, and assumptions called
for in the flowchart. There is a cross-reference between each
flowchart step requiring an operation and the corresponding item
in the worksheet. The Logic Summary and Flowchart can be used with
other types of worksheets or guidelines for calculations. The
Worksheets included herein are a suggested approach to aid the user
in performing the evaluations.
5. Notes - cover assumptions, reference information and sources, and
explanations related to specific flowchart or worksheet items.
The worksheets for each procedure are designed to be copied for repeated use.
They can be filled out and stored as the user proceeds through the framework
and the component methodologies to document the decisions, calculations, and
cost determinations. The FRAMEWORK METHODOLOGY WORKSHEET, Table 6-3, is used
to summarize the monetary cost and reliability information for all control
alternatives considered for each source, and for monitoring progress in con-
sidering load-reduction strategies and sources. Worksheets for the components
should be placed behind the framework worksheet, Table 6-3, in the order in
which they are considered. The illustrative example in Section 6.5 includes
a sample set of worksheets used in the development and evaluation of control
alternatives for the hypothetical South River planning area.
The Logic Summary, Flowchart, and Worksheets offer increasing levels of so-
phistication and detail in the evaluation of control alternatives. The user
should use the level of detail which best fits his particular situation and
needs. In addition, other techniques or approaches to specific operations
within any of the component methodologies should be substituted where the
user desires or has more up-to-date or site-specific information.
6-31
-------
Level of Analysis
/
Difficulties may arise when determining the appropriate level of analysis.
These difficulties arise from the complexity of many planning areas, the
dissimilarity of the alternatives being compared, the various degrees of
detail necessary to adequately characterize various alternatives, and the
variability in the quantity and quality of information available on various
alternatives.
The level of analysis for a particular planning area will be a function of
the complexity of the area, the types of pollution sources, and the amount
of information readily available on these sources. Highly complex areas
will require the use of simplifying assumptions (e.g., aggregation of loads);
this tends to decrease the usefulness of the performance and cost determina-
tions if specific sites or sources are of concern.
However, the objective of the overall process must be kept in mind, i.e., to
obtain a preliminary evaluation of various approaches to areawide problems.
Also, depending on the particular needs and/or background of the planner or
engineer using the manual, the methodology determinations may be based on
site-specific information, actual data in place of assumptions, or more so-
phisticated techniques if these are available. In addition, if the area is
complex and if loads have been aggregated and assumptions made, the method-
ology may be applied a second time in order to examine in more detail the
sources or alternatives of particular interest.
6.4.2.2 Framework Methodology
Discussion
The FRAMEWORK METHODOLOGY is a guide for the entire process of developing and
evaluating control alternatives. Within this framework, the user considers
each source under each load-reduction strategy, and investigates various con-
trol alternatives for that source. The investigation of control alternatives
is accomplished by using component methodologies applicable to the wastewater
sources involved. An overview of the FRAMEWORK METHODOLOGY is presented in
Figure 6-6, which shows the position of the component methodologies in the
framework.
6-32
-------
FIGURE 6-6
FRAMEWORK METHODOLOGY
OVERVIEW
»| Consider a Load-Reduction Strategy. |
Dry-Weather Flow:
Continuous Point
v
TREATMENT
FACILITY
METHODOLOGY
Cpg. 6-44)
1
LAND APPLICATION
METHODOLOGY
(pg. 6-63)
If all sources covered by
have not been considered,
the next source.
f*\ liOnsidcr
a Source. j
/'sourceV Wet-Weather Flow:
Sources ^ \Typef Interm
>,. / Urban
i
wAb 1'tsWA'i
METHO
Cpg.
>
IMPAC
MODIFI
METHO
Cpg.
f
ER REUSE
DOLOGY
6-140)
^
T AREA
PATTnM
DOLOGY
6-156)
1
a strategy I
address / >^
ittent Point and
^Ion-point Sources
i >
LAND MANAGEMENT
METHODOLOGY
Cpg. 6-83)
V
COLLECTION SYSTEM
CONTROL
METHODOLOGY
(pg. 6-92)
*
STORAGE/
k TREATMENT
METHODOLOGY
Cpg. 6-107)
REGIONALIZATION
METHODOLOGY
Cpg. 6-175)
If all load reduction strategies
for the 208 area have not been con-
sidered,.address the next strategy.
6-33
-------
The FRAMEWORK METHODOLOGY logic considers two basic types of sources: wet-
weather sources and dry-weather sources. As shown in Figure 6-6, wet-weather
sources of interest fall into two general categories: 1) intermittent point
sources (such as separate storm and combined sewer overflows); and 2) non-
point sources (such as runoff from construction sites, landfill sites, and
urbanized areas). Dry-weather sources of greatest concern are continuous
point source discharges, such as municipal and industrial wastewater ef-
fluents. Figure 6-6 shows the component methodologies for investigating con-
trol alternatives for the two types of wastewater flows.
Wet-weather wastewater flows can be handled at several points. The LAND
MANAGEMENT METHODOLOGY covers control alternatives which can be used to
reduce the quantity of runoff or the runoff loadings at the source. The
COLLECTION SYSTEM CONTROL METHODOLOGY covers alternatives which can-be
applied to flows after they enter the collection system to reduce the quantity
of flow or pollutant load that reaches the stream as an overflow or bypass.
Finally, the STORAGE/TREATMENT METHODOLOGY covers alternatives to store and
treat overflows at the end of the collection system to reduce the pollutant
loadings.
Dry-weather wastewater flows from continuous point sources are generally
managed by treatment and discharge to a receiving water, or by treatment and
application to the land. The TREATMENT FACILITY METHODOLOGY covers new-plant
construction or plant expansion and upgrading, and the LAND APPLICATION
METHODOLOGY covers application of wastewater to the land after some level of
pretreatment at a facility.
Control alternatives common to both wet- and dry-weather flows are considered
in WASTEWATER REUSE METHODOLOGY, IMPACT AREA MODIFICATION METHODOLOGY, and
REGIONALIZATION METHODOLOGY. Several component methodologies which are
utilized by other of the component methodologies are not shown in Figure 6-6
because they are not employed separately. These are the TRANSPORTATION
METHODOLOGY, RESIDUALS DISPOSAL METHODOLOGY, and PRESENT-WORTH METHODOLOGY.
A component methodology guides the user in determining if the performance
»
capability of a control alternative for a particular source meets the re-
quirements of the load-reduction strategy. Then, the monetary cost of
6-34
-------
implementing the control alternative is determined.
Methodology Logic
A summary of the logic of the FRAMEWORK METHODOLOGY is presented in Figure
6-7. An expanded flowchart, Figure 6-8, lists the steps to be taken in de-
termining performance^ and costs. The worksheets for recording the operations
are presented as Table 6-3. Notes on specific steps or worksheet items are
presented after the worksheets.
6-35
-------
FIGURE 6-7
FRAMEWORK METHODOLOGY
LOGIC SUMMARY
( BEGIN J
I
Identify water quality objectives, load {Step 1
reduction strategies, and sources to be
considered.
For each strategy, identify feasible
control alternatives for each source
based on performance, and determine
monetary cost and relative reliability
of performance and cost information
for each feasible control alternative.
1
Step 2
( END J
6-36
-------
FIGURE 6-8
FRAMEWORK METHODOLOGY
FLOWCHART
Identify
strategy,
water quality
sources to be
(
objectives,
considered.
BEGIN J
^
load reduction
Step la
Consider a load reduction strategy.
i
Consider a source.
Step Ib
r
Step Ic
/TABLE 6-3 /
Item 1 / .
TABLE 6-3
Item 1
TABLE 6-
Item
6-3 /
1 /
No
Determine if constructing a new plant or upgrading
and/or expanding an existing facility is a feasible
control alternative, and determine monetary cost
and relative reliability of performance and cost
information using TREATMENT FACILITY METHODOLOGY.
Step 2a
TABLE 6-3
Item 2
6-37
-------
FIGURE 6-8 (CONTINUED)
FRAMEWORK METHODOLOGY
FLOWCHART
Y
Determine if applying wastewater to the land is
a feasible control alternative, and determine
monetary cost and relative reliability of per-
formance and cost information using LAND
APPLICATION METHODOLOGY.
Step 2b
_>./ TABLE 6-3 /
/ Item 2 /
Determine if control of runoff at the soi
through land management is a. feasible cor
alternative, and determine monetary cost
relative reliability of performance and c
information using LAND MANAGEMENT METHODC
i
i
irce
itrol
and
:ost
)LOGY.
Determine if the reduction of runoff pollu-
tant loads through collection system controls
is a feasible control alternative, and determine
monetary cost and relative reliability of per-
formance and cost information using COLLECTION
SYSTEM CONTROL METHODOLOGY.
i
1
Determine if the reduction of pollutant loadings
from separate storm and combined sewer overflows
through storage and/or treatment is a feasible
control alternative and determine monetary cost
and relative reliability of performance and cost
information using STORAGE/TREATMENT METHODOLOGY.
Step 2c
Step 2d
Step 2e
TABLE 6-3,
Item 2
TABLE 6-3,
Item 2
TABLE 6-3
Item 2 /
6-38
-------
FIGURE 6-8 (CONTINUED)
FRAMEWORK METHODOLOGY
FLOWCHART
Y
Determine if the reduction of wastewater loads
through the reuse of wastewater is a feasible
control alternative and determine monetary cost
and relative reliability of performance and cost
information using WASTEWATER REUSE METHODOLOGY.
Step 2f
TABLE 6-3.
Item 2
Determine if the modification of the impact area
of a wastewater discharge is a feasible control
alternative, and determine monetary cost and
relative reliability of performance and cost
information using IMPACT AREA MODIFICATION
METHODOLOGY.
Step 2g
TABLE 6-2
Item 2 A
No
Have
all sources
been
considered?
Determine if treating wastewaters or sludges at
one site rather than at several sites through
the regionalization of facilities is a feasible
control alternative, and determine monetary cost
and relative reliability of performance and cost
•information using REGIONALIZATION METHODOLOGY.
TABLE 6-3
Item 2 /
No
ave
all
strategies
been
considered?
6-39
-------
TABLE 6-3
FRAMEWORK METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in the flowcharts
and worksheets are for guidance only, and should not be interpreted as the only ap-
proach available (or even as the preferred approach). However, any approaches used
should be consistent with EPA Cost Effectiveness- Analysis Guidelines and all other
EPA, State, and local guidelines and regulations.
Identification of water quality objectives, load reduction strategies, and
sources.
a. Define water quality objectives by number and parameters to be
controlled.
Receiving Water Constituents to be Controlled
Water Total SuspendedTotal
Quality D.O. (Dry D.O. (Wet Solids Total Total Coliforms
Objective # Weather) Weather) (Wet Weather) Nitrogen Phosphorus (Wet Weather)
b. Load reduction strategies represent differing percentage reductions in
load at the various sources of interest for a particular water quality
objective. These strategies are identified by a letter (a, b, c, etc.)
where more than one strategy is proposed for a particular water quality
objective.
c. Identify sources by number:
Source Type
Source fr (Het or Dry) Source Description
By | Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-40
-------
TABLE 6-3 (continued)
FRAMEWORK METHODOLOGY
WORKSHEET
Item 1 1 (continued)
ii. Record of load reduction strategies and sources considered.
• Check (x) the sources to be considered under each load-
reduction strategy.
• Circle the checks in the matrix after all appropriate control
alternatives have been considered for a source.
8 Go to next load reduction strategy when all sources have been
considered for that strategy.
• End when all strategies have been considered.
By
Load Reduction
Strategy
Source Number
1
2
3
4
5
6
Date
Checked by
Date
'
Strategy No.
Source No.
Remarks:
Page
6-41
-------
TABLE 6-3 (continued)
FRAMEWORK METHODOLOGY
WORKSHEET
Item 2]- Feasible Control Alternatives.
i. Record the Present-Worth cost of control alternatives determined using
the component methodologies.
ii. Record the worksheet page number (from lower right corner) where the present
worth is recorded in the appropriate component methodology.
iii. Record the relative .reliability of the performance and cost information for
the control alternative as identified in Appendixes G and H or at the
discretion of the user.
Load Reduction Information Reliability
Strategy Source Control Alternative Present-Worth $ Page Performance Cost
By Date Strategy No.
Checked by Date Source No«
Remarks: Pa9e_
6-42
-------
Notes on Methodology Logic
Step 1 (Item li) - The determination of water quality objectives and the de-
velopment of load-reduction strategies to achieve these objectives should
take place before the development and evaluation of control alternatives.
The water quality constituents to be controlled in order to achieve each
objective are identified in Item li. As explained in the worksheet, a load-
reduction strategy states the degree to which various sources are to be
controlled in order to reduce pollutant loadings. There may be several
strategies for achieving each water quality objective. For this manual,
any reference to a load-reduction strategy should be taken as a reference
to the strategy water quality objective combination. Also, the sources of
interest in the study area are numbered for ease of reference.
Step 1 (Item lii) - The framework methodology is employed as an iterative
technique to investigate feasible control alternatives for each source
within each load-reduction strategy. Step 1 guides the user through the
selection of the particular load-reduction strategy and source that he will
be looking at for any particular iteration. Later steps in the framework
methodology bring the user back to these steps if there is another source
to be considered for one particular load-reduction strategy, or for other
load-reduction strategies to be considered for the planning area.
Also, Item lii of the control methodology worksheet provides a place for
the user to keep track of exactly where he is in the iterations.
The control box just after Step Ic directs the user to the appropriate
steps in the flowchart, depending on whether he is considering a wet-weather
source or a dry-weather source.
Step 2 [Item 2) - This step sends the user to the appropriate component
methodology in order to test the feasibility of the control alternative and
to determine the monetary cost. The cost and information reliability (from
Appendixes G and H) for each control alternative considered is recorded in
Item 2.
6-43
-------
6.4.2.3 Treatment Facility Methodology
Discussion
The purpose of this methodology is to identify the monetary costs incurred in
treating a wastewater to meet a specific effluent quality. This methodology
will identify the cost for constructing new facilities, expanding existing
facilities, upgrading existing facilities, or expanding and upgrading existing
facilities.
The TREATMENT FACILITY METHODOLOGY provides the user with an approach that
will develop the facility costs in the desired detail. It should be noted,
however, that in the 208 planning process, generalized treatment levels such
as those present in the treatment system curves in Appendix H (e.g., secondary
treatment, advanced waste treatment, etc.) will usually be sufficient to pro-
vide ample cost information for making decisions in the overall management
picture. However, in many cases, the user-may have site-specific facility
data (e.g., 201 facilities plans) which will provide cost estimates of a
higher confidence level.
The TREATMENT FACILITY METHODOLOGY facilitates consideration of phased con-
struction for a control alternative capable of meeting the effluent criteria
based on population growth characteristics within the planning area. There-
fore, the facility cost that is being developed will be based on a more real-
istic consideration of the time-value of project costs. The methodology also
encourages and facilitates the evaluation of existing facility utilization.
It should be noted, however, that upgrading and expanding existing facilities
which are old, outmoded, etc., often represents a financial drawback. For
example, upgrading or expanding an existing facility, and working in and
around existing equipment, often requires non-optimal construction techniques.
A correlation is presented in Appendix H, Figure H-l, that shows a relation
between the additional cost associated with expansion as a function of the
expansion flow. This can serve as a rough guide for estimating the increased
capital associated with expansions.
Also, provisions are included to identify the costs for replacing worn-out
equipment at the end of its service life, and also for crediting value 'to
salvageable equipment at the end of the planning period. This should ensure
6-44
-------
that proper consideration has been given to all major factors that influence
economical comparisons of facilities.
While not specifically addressed in the TREATMENT FACILITY METHODOLOGY, the
user should consider other factors such as siting requirements and site char-
acteristics (e.g., flood hazards, surrounding land-uses, utilities, and rail
and highway access) in evaluating treatment alternatives. These factors will
reflect not only differential costs, but also comparative site suitability.
Consideration of these factors should be coordinated with the REGIONALIZATION
METHODOLOGY. For additional guidance in facilities planning, the user should
consult references (12) and (13).
Methodology Logic
A summary of the logic of the TREATMENT FACILITY METHODOLOGY is presented in
Figure 6-9. An expanded flowchart, Figure 6-10, lists the steps to be taken
in determining performance and costs. The worksheets 'for recording the oper-
ations are presented as Table 6-4. Notes concerning the methodology steps
and worksheet items are presented after the worksheets.
6-45
-------
FIGURE 6-9
TREATMENT FACILITY METHODOLOGY
LOGIC SUMMARY
ENTER
Determine project schedule and treatment [ Step 1
requirements. ^"~'~~~~"
Determine existing treatment facility [ Step
costs: Replacement' Cost, or Salvage
Value.
Determine, facility expansion capital cost I Step 3
for each project phase or new facility *————-
cost.
Determine capital cost of upgrading for | Step 4
each project phase.
Determine other costs for each project j Step 5
phase: 0§M Cost, Replacement Cost or
Salvage Value.
{ Determine residuals disposal costs. | Step 6 j
Determine project cost schedule and I Step 7
Present-Worth cost.
f CONTINUE)
6-46
-------
FIGURE 6-10
TREATMENT FACILITY METHODOLOGY
FLOWCHART
f ENTER J
\
f
Determine program construction
phases.
i
Step la
/TABLE 6-4 /
...'»»/ » i /
7 Item 1 /
i
Identify treatment objectives
and existing facility charac-
teristics.
\
Step Ib
r
Determine existing facility
capital value.
>
Step 2a
/TABLE 6-4/
7 item 1 /
/TABLE 6-4 /
7 Item 2 /
f
Determine .existing facility
replacement cost if planning
period is greater than re-
maining service life.
>
Step 2b
r
Determine existing facility
salvage value at end of
planning period, if remaining
service life is greater than
planning period.
>
Step 2c
i
Consider a project phase.
Step 3a
/TABLE 6-4 /
7 Item 2 /
/TABLE 6-4 /
IE/ /
7 Item '2. /
/TABLE 6-4/
Does
this phase include
construction of a new
facility?
6-47
-------
FIGURE 6-10 CCONTINUED)
TREATMENT FACILITY METHODOLOGY
. FLOWCHART
Y
Determine the construction
cost of the new facility.
Step 3b
Continue.
Step 3c
Does
this phase
include a facility
expansion?
Identify expansion require- Step 3d
ment and cost curve.
Determine capital cost of [ Step 3e /TABLE 6-4/
expansion. */ Item 5 y
/TABLE 6-4
Item 3
4/
/
/TABLE 6-4/
~7 Item 3 /
Continue.
Step 4a
6-48
-------
FIGURE 6-10 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
FLOWCHART
Y
Identify level of treai
and cost curves to be \
for upgrading using th<
ment systems matrix in
H or facility cost cun
from unit process cost
Appendix H or elsewher<
i
Determine capital cost
of upgrading.
^
Determine 0§M cost at .
and end of phase.
tment |Step 4b
ised
3 treat -
Appendix
ire synthesized
curves in
* •
(
|step 4c
/TABLE 6-4 /
7 Item 4 /
/TABLE 6-4 /
7 Item 4 /
i
start Step 5 a
/TABLE 6-4 /
7 Item 5 /
Determine the __
replacement cost
for this facility.
/TABLE 6-4/
7 Item 6 /
salvage value at
end of planning period.
6-49
-------
FIGURE 6-10 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
FLOWCHART-
Yes
Determine residuals disposal
cost schedule using the
RESIDUALS DISPOSAL METHODOLOGY
^
>
Record costs on Project
Cost Schedule.
i
t
Determine Present-Worth
costs.
)
i
Record Present-Worth cost
and information-reliability
of treatment facility-construe
in Item 2 of FRAMEWORK METHODO
WORKSHEET, TABLE 6-3.
\
t
Step 6
•
Step 7a
Step 7b
Step 7c
tion
LOGY
^y
V
^J
z.
^jl
-^i
^ynTABLE 6-4
y Item 8
4/
/
/TABLE 6-4/
y Item 10 /
/TABLE 6-3/
•y Item 2 /
CONTINUEIj
6-50
-------
TABLE 6-4
TREATMENT FACILITY METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
[Item 1 - Program Implementation Schedule.
i. Planning Period: 20 years
ii. Construction phases:
Flow Design
Phase Timing Projection (mgd) Flow (mgd)
'Start ' 'End
1*
2
3
4
n
*Existing facility not utilized at full capacity.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-51
-------
TABLE 6-4 (continued)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Phase
Existing
Facility
1
2
3
n
Effluent Quality
Reference
Cost
Curve**
BOD
mg/1
COD
mg/1
TSS
mg/1
T-P
mg/1
NH3-N
mg/1
N03-N
mg/1
T-N
mg/1
T-C
#/100ml
iii. Treatment Objectives.
Note: Dissolved oxygen deficits use ultimate oxygen demand inputs
(Table 6-3). These must be reconverted back to CBOD and NBOD (NH3)
concentrations to determine discharge limitations (See Appendix H
discussion of Treatment Systems Performance Matrix).
**Treatment System curve number (Appendix H, Figures H-2 to H-15) or
reference number for synthesized system cost curve developed from
unit process curves (Appendix H).
iv. Existing Facility Characteristics.
Design Capacity:
Service Life:
mgd
years
Years in Service:
Remaining Service:
years
years
By
Checked by_
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-52
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 2| - Existing Facility Cost.
Note: For the first phase of new facility construction, Items 2i,
2ii, and 2iii will equal zero .since there is no existing
facility.
i. Capital Value (i.e., construction cost plus add-ons).
a. Design Q = mgd
b. Level of Treatment: Reference Cost Curve
Service Life
c. Construction Cost (Curve $)
d. plus Piping - Curve $ x 15%
Electrical - Curve $ x 12%
Instrumentation - Curve $ x 8%
Site Preparation - Curve $ x 5%
Miscellaneous Structures
e. Sub-Total 1, Construction Cost (c+d)
f. plus Sub-Total 1 x Engineering and
Construction 15%
Sub-Total 1 x Contingencies 15%
g. Sub-Total 2: Capital Cost (e+f)
h. CAPITAL VALUE OF ENR (Current)
EXISTING FACILITY = Sub-Total 2 x 2375*=
* ENR = 2475, September, 1976. '
ii. Replacement Cost.
(compute only if planning period is greater than remaining service
life)
/
Replacement Planning Period - Remaining Service Life „ Capital
Cost = Planning Period Value
= at year
iii. Salvage Value.
(compute only if remaining service life is greater than planning
period)
Salvage Value = Remaining Service - Years to Planning End Y Capita]
Remaining Service" Value
= at end of planning period.
By - Date Strategy No.
Checked by__ Date Source No,,
Remarks: . Page
6-53
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Ite
i
m 3 - Expansion Program or New Facility Construction.
Phase Number
Existing Capacity = mgd (previous phase or
cility; zero it ne
ii. Expanded or New
Facility Capacity =» mgd (design capacity
i
i
V
•v
\
\
i
•i-i . T.evel of Treatment: Reference Cost Curve
Service Life
v. Construction cost of expanded or new facility -
enter cost curve at expanded or new facility at
capacity (ii)
Construction cost of existing facility -
enter cost curve at existing facility at
capacity (i)
i. Sub-Total 1: Expanded or New Facility
Construction Cost (iv-v)
di. plus Sub-Total 1 x Piping 15%
Sub-Total 1 x Electrical 12%
Sub-Total 1 x Instrumentation 8%
Sub-Total 1 x Site Preparation 5%
aii. Sub-Total 2: Construction Cost (yi + vii)
x pi, i* Sub-Total 2 x Expansion/Upgrading Factor
Sub-Total 2 x Engineering and
Construction 15%
Sub-Total 2 x Contingencies 15%
t. Sub-Total 3: Capital Cost (viii + ix)
iri . CAPITAL COST OF ENR (Current)
EXPANSION OR OF = Sub-Total 3 x 2475*
existing fa-
w facility)
of next phase)
—
=
s
=
_
_
=
NEW FACILITY
* ENR (Engineering News Record) = 2475, September, 1976.
By
Chet
Date Strategy No.
;ked by Date Source No.
Remarks:
Page
6-54
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 4
i.
ii.
iii.
iv.
V.
vi.
vii.
viii
ix.
X.
xi.
By
Checked
Rema rks
1 - Upgrading Program.
Phase Number
Existing Level of Treatment: Reference Cost Curve
(previous phase or existing "facility)
Required Level of Treatment: Reference Cost Curve
ffor the identified phase) Service Life
Q = mgd (design capacity)
Construction Cost at required level of
treatment - curve from ii
Construction Cost at existing level of
treatment - curve from i
Sub-Total 1: Construction Cost of Upgrading
fiv-v) =
plus Sub-Total 1 x Piping 15% =
Sub- Total 1 x Electrical 12%
Sub-Total 1 x Instrumentation 8% =
Sub-Total 1 x Site Preparation 5% =
Sub-Total 2: Construction Cost Cvi + vii)
plus Sub-Total 2 x Expansion/Upgrading Factor =
Sub-Total 2 x Engineering and
Construction 15% =
Sub-Total 2 x Contingencies 15% =
Sub-Total 3: .Capital Cost fviii + ix)
CAPITAL COST ENR (Current)
OF UPGRADING - Sub-Total 3 x 2475* =
* ENR = 2475, September, 1976.
Date Strategy No.
by Date Source No.
: Page
6-55
-------
TABLE 6-4 CCONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 5 - 0§M Constant and Variable Cost.
Phase
Level of Treatment: Reference Cost Curve
Timing Design Flow 0§M Cost
Start End Start End Start End
(yr.) (yr.} (mgd) (mgd)
$ $.
Item 6 | - Phase Replacement Costs (Upgraded and/or Expanded Portion)
(Compute if planning period is greater than phase service life)
Replacement Cost Schedule.
Expansion Upgrading Total
Year Cost Year Cost Year Cost
Replacement Cost for Phase =
Years from Time of Replacement to End of Planning Period '
: Service Life X Ca?ltal
IItem 7 I - Phase __; Salvage Value at End of Planning Period.
(Compute if phase service life is greater than years to planning
period end)
(Service Life - Years to Planning End) r . ,
Salvage Value = -i Service Life X Capltal
Expansion S.V. = $ ;
Upgrading S.V. = $
Total Phase S.V. $
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-56
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 8| - Residual Disposal Cost, using RESIDUALS DISPOSAL METHODOLOGY.
i. Residual Disposal Technique.
Solids Nature
Residual Type
Disposal Method
Transportation
ii. Residual Disposal Cost Schedule.
Phase
Land
Cost
1
2
3
n
Timing
Yr. to Yr.
Capital
0§M
Start
End
Replacement Cost
Year
Cost
Salvage
Value
By
Checked by_
Rema rks:
Date
Date
Strategy No.
Source No.
Page
6-57
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 9 - Project Cost,Schedule (Summary of costs developed in
TREATMENT FACILITY METHODOLOGY).
Phase Year to Year
Item No.
Capital Start End Variable Salvage
Cost OW 0$M ' 05M Value
3 (Expand/New)
4 (Upgrade
5/6/7
8 (Residual)
Total Phase 1
3 (Expand/New)
4 (Upgrade)
5/6/7
8 (Residuals)
Total Phase 2
3 (Expand/New)
4 Upgrade)
5/6/7
8 (Residuals)
Total Phase 3
n
3 (Expand/New)
4 (Upgrade)
5/6/7
8 (Residuals)
Total Phase n
Replacement Schedule
Year Cost
- Present-Worth Cost, using PRESENT-WORTH METHODOLOGY
Interest
_% (from Water Resources Council
18 CFR 704.39, Discount Rate,
published annually)
Present-Worth Cost $
By
Checked by
Rema rks s
Date
Date
Strategy No.
Source No»
Page
6-58
-------
Notes on Methodology Logic
Step la (Item li) - This step identifies the program implementation schedule.
The flow projection represents the anticipated wastewater flow at the be-
ginning and end of each phase. The design flow, however, represents the
desired treatment facility capacity to be provided for the duration of the
phase. Therefore, facility construction costs are defined by an increase
in the design flow, while the gradual increase of 0§M costs will be identi-
fied by the flow projection.
Step Ib (Item lii) - This step identifies the treatment objectives to be met
during the various phases of construction throughout the planning period.
Included are design flows and effluent characteristics for each of the phases.
Also identified are the cost curves applicable to the identified treatment
levels which can be either the systems curves included in Appendix H, a
special curve synthesized from the unit process cost curves, or other
acceptable cost curves. The condition of the existing facility is identi-
fied in terms of effluent characteristics and useful life (remaining service
life).
Step 2a (Item 2i) - This step determines the value of the existing treatment
facility, using the cost-curve information in Appendix H. This information
is adjusted to reflect installed costs based on the identified percentage
factors or on better information (e.g., site-specific data) the user may
possess. The capital value does not actually represent the Present-Worth of
the existing facility because it is not adjusted for the remaining service
life. However, the capital value does represent the cost to build the
existing facility under present conditions, and is useful in defining the
phase out cost, replacement cost, or salvage value.
Step 2b (Item 2ii) - This step identifies the replacement cost associated
with an existing facility which is utilized in -the project but which -has a
remaining service life shorter than the planning period. This computation
assumes that the replacement cost is a lump sum that occurs at the end of the
service life and has no salvage value at the end of the planning period.
6-59
-------
Step 2c (Item 2iii) - This step identifies the salvage value at the end of the
planning period when the existing facility is utilized and has a remaining
(current) service life that exceeds the planning period. This service life
can be identified using the information presented in Appendix H for the
treatment systems or by another acceptable method.
Step 5a (Item 5) - In this step, a project phase is considered for detailed
cost evaluation. Note that Steps 3a through 5c (Items 3 to 7) will be re-
peated for each project phase.
Step 5b CItern 5) - This step determines the construction cost for a new
facility included in the phase under construction. The times in Worksheet
Item 3 pertaining to the value of existing facilities and the upgrade/
expansion factor are not relevant for new facilities and should be set to
zero.
Step 5c (Item 5) - No discussion.
Step 3d (Item 5j_ - In this step, the phases that include a treatment-plant
expansion are identified by the desired increase in capacity and the level
of treatment for the expansion.
Step 5e (Item 5) - In this step, the construction cost associated with the
expansion is determined using the Appendix H cost curves or an equivalent
synthesized curve and the identified construction factors. The upgrading/
expansion factor in Appendix H, Figure H-l, or equivalent, can be utilized,
when necessary, to refine this cost estimate to reflect the costs associated
with construction which adjoins existing structures.
Step 4a (Item 4) - No discussion.
Step 4b (Item 4) - In this step, the project phases that include upgrading
of a treatment facility are identified by the old (previous phase) treatment
level and the desired (upgraded) treatment level.
Step 4c (Item 4) - In this step, the cost associated with a treatment up-
grading is determined using the cost curves in Appendix H and the identi-
fied construction factors. The upgrading/expansion factor can be included,
6-60
-------
if necessary, to reflect the costs associated with construction which adjoins
existing structures.
Step 5a (Item 5) - In this step, the 0§M costs are identified for the phase.
Since, in general, the wastewater flow will increase during the phase under
consideration, the time pattern of 0§M costs has been approximated by con-
sidering constant and variable 0§M costs. The constant 0§M cost will be
incurred throughout the phase and will be determined by the initial flow
rate. The variable 0§M reflects the flow increase and is computed by
multiplying the average increase in the annual 0§M cost during the phase
Final 0§M Cost - Initial 0§M Cost
Elapsed Years
by the gradient series present-worth factor, which is described in the
PRESENT-WORTH METHODOLOGY. The required 0§M costs are included in the
systems curves in Appendix H or can be developed using the process curves
or their equivalent.
Step 5b (Item 6) - This step is used to identify the replacement cost
schedule for the upgraded or expanded facilities. These values are de-
veloped for facilities having a service life shorter than the years re-
maining in the planning period.
Step 5c (Item 7) - This step identifies the salvage value for the upgraded
or expanded facilities. This is computed for the expansion/upgrading or
new facilities for each phase, with the total project salvage value then
computed from the sum of the salvage values identified for the facilities
constructed during each phase.
Step 6 (Item 8) - This step identifies the residual-disposal technique, in-
volving nature of solids, types of residuals, disposal method, and trans-
portation. This item also includes a residual-disposal cost schedule. It
is important to note that the RESIDUALS DISPOSAL METHODOLOGY and TRANS-
PORTATION COST METHODOLOGY will be used to develop the cost schedule in Item
8.
Step 7 (Item 9) - The project cost schedule for each alternative is sum-
marized in this step. A phase-by-phase schedule allows orderly consolidation
6-61
-------
of the cost values determined throughout this methodology. The item and
number indicated on this schedule correspond to the item numbers of the
TREATMENT FACILITY METHODOLOGY. It will generally be easiest to combine the
identified start and end 0§M costs (e.g., expansion plus residuals) and com-
pute the variable 0§M costs for each phase by the method outlined in Step
5a. The data in this schedule are utilized in the PRESENT-WORTH METHODOLOGY.
Step 9a (Item 10) - This step records the interest rate and the computed
Present-Worth of the alternative. The present worth should also be entered
on the FRAMEWORK METHODOLOGY Worksheet.
6-62
-------
6.4.2.4 Land Application Methodology
Discussion
Although land application of a treated wastewater effluent can take many
forms, this methodology is designed to evaluate two types of systems:
1) the underdrained spray irrigation site which involves a point source dis-
charge of the treated effluent; and 2) the undrained spray irrigation site.
The former would serve as a treatment system and might be evaluated as an
alternative to existing or additional wastewater treatment unit processes.
The latter case would actually describe a disposal technique and might have
the added benefit of groundwater recharge or no discharge of pollutants to
the receiving stream.
Design criteria to be considered when selecting potential sites and, in
particular, when evaluating a specific disposal site, are well documented
in EPA guidance documents on land application systems. See references (14)
through (IS). The criteria for identifying potential sites should be devel-
oped for the specific areas of interest. The following items, while not all
inclusive, should be addressed during site identification:
• Land use patterns (e.g., land use restrictions, buffer zones).
• Socio-economic impacts (e.g., density of dwellings and other structures,
health risks, and traffic patterns).
• Physical characteristics of the site (e.g., soil groups, topography,
geologic conditions, ground-water conditions).
• Restricted areas (e.g., historical sites, sensitive environmental areas).
It is advisable in the identification of potential sites to establish the
evaluation criteria in conjunction with local officials; this will insure that
local concerns are properly considered.
The LAND APPLICATION METHODOLOGY describes the evaluation process for a
particular land-application/point-source combination. Factors that are con-
sidered in this evaluation include the water quality impact of the land dis-
posal alternative, the wastewater transportation cost, and the land appli-
cation site cost. The methodology computes these costs for several alterna-
tive land application sites.
6-63
-------
It is assumed that all wastewater flow from the point source is applied to
the land application site being evaluated. However, the methodology logic
could be readily modified by the user to handle specific situations where
wastewater from one point source is sent to several sites, or where only a
portion of the point source discharge is sent to a land-application site.
Finally, the user should be aware that much of the information, particularly
with respect to potential land-application sites, should be readily available
from earlier evaluations for the planning area. The user should utilize any
such existing data to simplify the evaluation process.
Methodology Logic
A summary of the logic of the LAND APPLICATION METHODOLOGY is presented in
Figure 6-11. An expanded flowchart, Figure 6-12, lists the steps to be
taken in determining performance and costs. The worksheets for recording
the operations are presented as Table 6-5. Notes concerning the method-
ology steps and worksheet items are presented after the worksheets.
6-64
-------
FIGURE 6-11
LAND APPLICATION METHODOLOGY
LOGIC SUMMARY
C ENTER J
Determine treatment requirements for land
application (LA) and for treatment and
discharge at the existing wastewater treat-
ment plant.
i
r
Determine area required for LA of point-
source wastewater.
i
r
Step 1
Step 2
Identify and evaluate potential sites for LA. Step 3
Determine cost for application pretreatment.
Step 4
i.
Determine land cost for LA.
Step 5
Determine transportation cost for LA.
>
Step 6
r
Determine LA site cost and potential revenues.| Step 7
Determine Present-Worth cost of LA.
I
( CONTINUE J
Step 8
6-65
-------
FIGURE 6-12
LAND APPLICATION METHODOLOGY
FLOWCHART
f ENTER ^
1
f
Identify project implementation schedule and
effluent limitation for treatment and discharge
at the treatment plant,,
^
Step la
/TABLE 6-5 /
7 Item 1 /
f
Identify regulatory pretreatment requirements
for land application (LA) of wastewaters.
^
r
Identify the project construction schedule „
i
t
Determine area required for LA considering
the point-source wastewater flow, a typical
weekly application rate for sites in the area,
and non-operating time attributable to environ-
mental constraints „
i
1
Identify potential sites for LA in or near
the planning area, based on site proximity,
land availability, and consultation with
appropriate public and private agencies 0
i
Identify the potential of each site, including
available area, site development, environmental
constraints, and physical configuration.
\
f
Consider a specific potential site. Identify
the level of pretreatment required for LA.
Identify the actual performance characteristics
at the existing treatment facility. Determine
if evaluation is for an undrained or under-
drained system.,
>
f
Step Ib
/TABLE 6-5 /
7 Item 1 /
Step Ic
Step 2
Step 3a
Step 3b
Step 4a
/TABLE 6-5 /
7 Item 1 /
/TABLE 6-5 /
7 Item 2 /
/TABLE 6-5 /
7 Item 3 /
/TABLE 6-5 /
7 Item 4 /
/TABLE 6-5 /
7 Item 5 /
6-66
-------
FIGURE 6-12 (CONTINUED)
LAND APPLICATION METHODOLOGY
FLOWCHART
YeT
Does
existing
facility treat
to at least the level
^identified in Step Ib and will,
it for the duration oi
LA planning
period?
No
Determine the cost to upgrade treatment
flow for LA to level identified in Step
using TREATMENT FACILITY METHODOLOGY.
i
!
of
Ib
Step 4b
Identify the disposal area required at the
site, and determine land cost schedule for
the site.
i
t
Step 5
Determine the cost of transporting the
wastewater to the LA site using TRANSPORTATION
METHODOLOGY.
i
1
Step 6
Determine the land application site cost
schedule and potential revenues (e.g., cropping).
i
r
Step 7
^ /TABLE
y Item
6-5 /
6 /
/TABLE
7 Item
6-5 /
7 /
/TABLE
7 Item
s'V
/TABLE
7 Item
Determine the total cost schedule for LA
at the site.
>
i
Step 8a
/TABLE
7 Item
6-5 /
9 /
6-5 /
10 /
6-67
-------
FIGURE 6-12 (CONTINUED)
LAND APPLICATION METHODOLOGY
FLOWCHART
Have
all poten-
tial sites been
considered?
Go back to
Step 4a
Determine the total Present-Worth cost
potential sites considered.
• - i
Record the Present-Worth cost and infc
tion reliability for LA in Item 2 of t
FRAMEWORK METHODOLOGY WORKSHEET, TABLE
i
. at the | Step 8b
/TABLE 6-5 /
J Item 11 /
r
>rma- Step 8c
.he
, 6-3.
f
/TABLE 6-3 /
7 Item 2 /
C
CONTINUE
6-68
-------
TABLE 6-5
LAND APPLICATION METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approach used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
PROJECT SCHEDULE
Item 1|- Program Implementation Schedule.
io Planning Period: 20 years
Existing Facility Conditions„
11.
111.
Design Capacity:
Years of Service:
Remaining Service:
Treatment Levels.
mgd
years
years
Note: Dissolved oxygen deficits use ultimate oxygen demand inputs
(Table 6-3). These must be reconverted back to CBOD and NBOD
concentrations in order to determine discharge limitations (See
Appendix H discussion of Treatment Systems Performance Ratios).
Level
Existing
Facility
Pretreatmenl
Discharge
Limitations
Reference
Cost
Curve
Parameter Control Levels
BOD
mg/1
COD
mg/1
TSS
mg/1
T-P
mg/1
NH3-N
mg/1
N03-N
mg/1
T-N
mg/1
T-C
#/100ml
IV.
Construction Phases:
Phase
1
2
3
n
Timing
Year to Year
Design Flow (mgd)
Flow Projection
Start
End
Pretreatment
Start
End
Transportation
Site
Start
End
By
Checked by
Rema rks t
Date
Date
Strategy No.
Source No.
Page
6-69
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
GENERAL SITE EVALUATION
- Land Application Ultimate Area Requirement.
Maximum Annual Flow Rate at end of Planning Period = mgd
ii. Application Rate1 = in./week
iii. Non-operating time = weeks/year
i.
iv. Area Required = acres, without buffer zone
(includes area for roads, buildings, etc.)
Gross Area Required (with 200 ft buffer zone)2=
acres
(Use Nomograph "Total Land Requirement", Figure 6-13, or
equivalent)
Items 2ii and 2iii can be used for determining maximum capacity
for potential LA sites in Item 5.
2
Use a more stringent buffer zone limitation if indicated by
applicable Federal, State, or local regulations or site conditions.
By , Date . f Strategy No.
Checked by Date Source No.
Remarks: Page
6-70 '
-------
TABLE 6-5 CCONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
[item 5|- Potential LA Sites - Location.
(Attach USGS Quad Sheet or equivalent with potential sites outlined and
identified.)
By Date |___ Strategy No.
Checked by Date Source No.
Remarks:
6-71
-------
I
~J
K)
•ya r> co
(D — i" *^
3 0>
Q) O
T. jf
I/) Q-
cr
o
o
01 01
rt rt
0>
in
0>
in
O rt
C. -I
T 0)
O rt
0) fl>
(0
o
o
-o
01
\
Item 4
Site
- Potential LA Sites Data Sheet. (Sample of factors to be considered. This
is not an inclusive list; see LA references
for additional considerations.)
Approximate
Available
area
(acres)
Estimated
treatment
capacity
(mgd)
Area
of site
presently
irrigated
(percent)
Distance
from
plant
(feet)
Elevation
difference
from plant
(feet)
Homes
onsite
(No.)
Other
buildings
onsite
(No.)
Roads
onsite
(miles)
Comment s -
Major
problems or
advantages
> DO
T) f
*a m
o n
?o f-
son
m z
o m
a c
en
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
SPECIFIC SITE EVALUATION
SITE
Item 5 |- Site Implementation Schedule.
i. Planning Period: 20 .years
11.
111.
IV.
Construction Phases:
(If different from Project Schedule, then describe.)
Pretreatment Requirements: Reference Cost Curve
(If different from Project Schedule, then describe.)
Performance Characteristics - existing facility: Reference Cost
Curve (From Item liii)
Pre-application Treatment Cost.
Use Treatment Facility Methodology.
Phase
Existing
Facility
1
2
3
n
Timing^
Yr. to Yr.
Capital
OSM
Start
End
Replacement Cost
Year
Cost
Salvage
Value
Item 7 - Land Cost.
Application Rate =
Curve Rate =
Factor = Application Rate/Curve Rate =
_in./week
in./week
Phase
1
2
3
n
Design *
Flow
Adjusted2
Flow
Land Cost
Salvage Value
Design Flow is the desired application site daily capacity addition for
,the project Phase. rr * '
Adjusted Flow = Design Flow x Factor
By
Checked by_
Rema rks:
Date
Date
Strategy No.
Source No.
Page
6-73
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
[Item 8 - Transpc
jrtation Cost.
i. Use Table 6-18, TRANSPORTATION COST METHODOLOGY to complete
following schedule:
Ph
i
ise Capital
1
2
3
a
0§M Salvage
Start End Value
Replacement
Year
[item 9|- Application Site Costs.
i. Use cost curve in A;
Timing^
Phase Yr to Yr
1
2
3
n
Flow Rate, mgd
Start End
ppendix I
Curve Nc
Service
Design,
mgd
Replacement
Year
Adjust curve c
^Develop Salvag
which reflects
^include crop r
By
Checked by
Rema rks :
Schedule
Cost
1, Figure H-16, or equivalent method:
).
Life
Capital 0§M
Cost Start End
Schedule
Cost
ost to reflect installed cost,,
e Value = Service Life - Years to Planning End
Service Life
the remaining Phase value at the planning per
evenues, etc.
Date
Date
Salvage2 Revenue3
Value Start End
• x Capital
iod end.
Strategy No.
Source No.
Page
6-74
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
' WORKSHEET
[Item 101- Monetary Cost Evaluation
Cost Schedule.
i.
Phase
1
Timing
Yr to Yr
Item
#6
#7
#8
#9
TOTAL PHASE 1
#6
#7
#8
#9
TOTAL PHASE 2
#6
#7
#8
#9
TOTAL PHASE 3
Capital Start End Variable Salvage Revenues
Cost 0§M 0§M 0§M Value Start End
By
Checked by_
Rema rks:
Date
Date
Strategy No.
Source No.
Page
6-75
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
Item 10
- Monetary Cost Evaluation (Continued).
Timing Capital Start End Variable Salvage Revenues
Phase Yr to Yr item Cost 0§M 0§M 0§M Value Start End
#6
#7
#8
#9
TOTAL PHASE 4
Replacement Schedule
Item Year Cost
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-76
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
PRESENT-WORTH COST EVALUATION
[item ll|- Present-Worth Cost.
Site Present-Worth Cost Reference Sheet
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-77
-------
Notes on Methodology Logic
Step la (Item li, ii, iii) - The project implementation schedule is developed
by considering the projected wastewater quantity estimates for the planning
area, existing facilities, state and Federal requirements, and local factors.
In many cases, the user will wish to identify a phased program that is
identical to that developed for the wastewater treatment facility evaluation,
since this will allow a direct comparison of the monetary costs associated
with each alternative during each phase. The effluent limitation for treat-
ment and discharge should be available from a previous evaluation; if not,
the user can develop the required control level using the water quality im-
pact analysis techniques described in Chapter 5. The required level of
treatment can then be determined: from the Treatment System Performance
Matrix (Table H-3), from a synthesis of the unit process curves, or their
equivalent.
Step Ib (Item liii, iv) - In this step, the requirements for land-application
pretreatment are defined. The user should identify any regulations con-
cerning the minimum acceptable pretreatment for land application in the plan-
ning area. Where appropriate, the characteristics of the land in the planning
area should be considered in the determination of the required pretreatment
level. In the general case,'secondary treatment or equivalent should be con-
sidered the minimum that will insure adequate site performance.
Step Ic (Item liv) - This step identifies the construction program to be
evaluated for the land application alternative. The various aspects of the
project (pretreatment, transportation, application site) can have different
design flows during the project, since these are evaluated individually.
However, each of the individual project considerations should be keyed to
the same phase timing to facilitate the development of the project schedule.
Step 2 (Item 2) - The purpose of this step is to identify the area require-
ments for a land-application site. The factors that should be considered for
sites in the planning area include the design flow rate of the wastewater
source, the allowable application rate Cin terms of applied inches per week},
and the require.d non-operating time. The design flow rate should be deter-
mined as an average flow, because storage facilities are usually provided
6-78
-------
at the land-application site. The user should identify any Federal, state, or
local regulations concerning allowable application rates at land-application
sites or siting requirements. The user should also consider the allowable
application rate at existing land-application sites in the planning area.
The non-operating time can be determined by considering the climate in the
immediate area.
In addition, the user should identify buffer zone requirements for land ap-
plication sites, as well as the area required for roads, buildings, and so
forth. To assist the user in determining the area required for land appli-
cation of the wastewater, a nomograph, Figure 6-13, has been provided. The
required area, both with and without a buffer zone, should be identified, so
that the user can identify the maximum capacity at a potential land-applica-
tion site.
Step 5a (Item 5) - In this step, potential land-application sites are identi-
fied. There are numerous factors to be considered in identifying the site,
and these are well documented in EPA guidance documents on land application.
Characteristics of the potential sites include proximity to the wastewater
source and adequate land availability, and should be evaluated utilizing the
recommendations of appropriate public and private agencies. The potential
sites should be shown on USGS quad sheets or equivalent topographic maps.
Step 5b (Item 4) - The potential sites identified in the previous step are
further evaluated in this step. The maximum wastewater capacity at each site
is determined using the nomograph "Total Land Requirement" (Figure 6-13) and
the application rate and non-operating time previously identified (Item 2).
However, the user can modify these typical numbers for any sites for which
they would not be applicable. The additional information requested for each
potential site should be available from an accurate topographic map, and
should be useful in identifying the most feasible sites for a particular
wastewater source.
Step 4a (Item 5) - In this step, one of the potential sites is selected for
a cost evaluation. The planning period and project phases are evaluated and
described in detail when they are different from the project schedule pre-
viously identified in Step la (Item 1). The application pretreatment level
6-79
-------
i
CO
o
^
5
CO
fi
c
o
1
'o.
Q.
20 -i
15 -
10 -
9 -
8 -
7 -
6 -
5 -
4 -
3 -
2 -
1 -
X
/
X
X
100 -3
50 - •/
~ /
s*
•n lO-
ta 1 \J
O) - >^
a» "~~
E ^^ 1
0) X" - O
.— 'X >
Q> Q,
0 1^
;
0.5^
~
0.1 J
30,000 -,
20,000 -
10,000-
— 5,000-
w
o 1 ,000 —
»
« 500-
CD
0
^
CO
CD
^ 100-
CO
0
50-
10-
c
- 30,000
— 20,000
- 1 0,000
— 5,000
in
-------
should be identified and the Treatment System Performance Matrix (Table H-3)
or a comparable method utilized to determine required treatment levels. The
user should identify whether an underdrained or undrained site is to be
evaluated based upon the site conditions, results of water quality impact
analysis in Chapter 5, and other site-specific factors. If desired, the
evaluation could be performed for both types of systems.
Step 4b (Item 6) - In this step, the user will identify the cost schedule
for wastewater pretreatment prior to land application, where the existing
facility is currently inadequate or will become inadequate (due to increased
wastewater flow, etc.) during the planning period. The TREATMENT FACILITY
METHODOLOGY should be utilized to develop this cost schedule.
Step 5 (Item 7) - In this step, the user will identify the area required at
the disposal site for each project phase. The cost of land can be determined
by the user on the basis of the average land cost in the area, which, if
necessary, can be obtained from the tax assessor. This step can be eliminated
when the total cost curve of Appendix H, Figure H-16, (which includes land
cost) is used, but only if the assumptions used to develop that curve are
valid for the system.
Step 6 (Item 8) - The cost to relocate the wastewater from the existing dis-
charge point to the proposed land-application site is determined in this step.
This can be determined using the TRANSPORTATION COST METHODOLOGY which will
identify the pipeline and pumping cost for transporting the wastewater.
Step 7 (Item 9) - In this step, the cost schedule for developing and expanding
the land-application site is determined in accordance with the desired project
phasing. When evaluating land application as a control alternative, the cost
associated with the underdrain system should also be developed for the site.
(Note: Figure H-16 in Appendix H is for undrained systems only.) Also,
potential revenues should be identified, including cash crops, etc. Although
the land-application cost curve includes an assumed storage requirement and
land-application rate, the user can modify the capital cost estimate to re-
flect the conditions at a specific site. In general, this adjustment is
proportional to the ratio of the site condition to the design condition. For
example, the cost for a 2.5 inch/week application site would be 2.0/2.5 times
6-81
-------
the cost described in the construction cost curve, which assumes a 2.0 inch/
week rate. The construction cost developed from the curve does not include
estimated costs for piping, electrical, instrumentation, construction, engi-
neering, or contingencies; these are figured separately using assumptions in
the introduction to Appendix H or site-specific data. Typically, the user can
identify these costs using a method similar to that described in the TREAT-
MENT FACILITY METHODOLOGY.
Step 8a (Item 10) - In this step, the cost schedules identified in Steps 4,
5, 6, and 7 (Worksheet Items 6, 7, 8, 9) are combined to represent the proj-
ect cost schedule of the land-application site.
Step 8b (Item 11) - The Present-Worth cost of this site is then determined
using the PRESENT-WORTH METHODOLOGY. Note that revenues represent a negative
cost and should be entered into this calculation as such.
6-82
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6.4.2.5 Land Management Methodology
Discussion
Land management control alternatives have great potential for cost-effective
water pollution control. However, the implementation of these control alter-
natives has been severely hindered because of the lack of information both in
regard to documentation of effective performance and in regard to cost. Fur-
thermore, implementation of land management decisions often has an impact on
or requires close and continuing interface with local institutions and social
customs, and the reactions and/or resistance are difficult to anticipate.
Quantitative data on performance and cost for the few land management control
alternatives for which such information is available are included in Appendix
G. Additional data on these alternatives and data on other alternatives not
currently included in Appendix G will become available when further develop-
ment of the relatively new field of land management will provide better un-
derstanding and documentation of its concepts and applications.
Methodology Logic
A summary of the logic of the LAND MANAGEMENT METHODOLOGY is presented in
Figure 6-14. An expanded flowchart, Figure 6-15, lists the steps to be taken
in determining performance and cost. The worksheets for recording the opera-
tions are presented as Table 6-6. Notes concerning the methodology steps and
worksheet items are presented after the worksheets.
6-83
-------
FIGURE 6-14
LAND MANAGEMENT METHODOLOGY
LOGIC SUMMARY
(
ENTER
Identify land uses or land use [Step
activities of concern.
Identify land management control I Step 2
alternatives capable of meeting
performance requirements.
Determine Present-Worth cost ofIStep
land management control alterna- '
tives.
C
CONTINUE
6-84
-------
FIGURE 6-15
LAND MANAGEMENT METHODOLOGY
FLOWCHART
ENTER
l
f
Identify land uses or activities and pollutant
types and quantities in the subarea of concern
from the load assessment procedures presented
in Chapters 2 and 3.
^
r
Step 1
Determine applicable land management control
alternatives using TABLE 6-7.
)
r
Identify load reduction requirements fr(
Load Reduction Strategy Matrix.
1
r
Step 2a
/TABLE
y Item
6-6 /
1 /
/TABLE
*7 Item
ym the
Step 2b
^ /TABLE
7 Item
Identify performance capability of applicable
land management alternatives, as applied to
land uses and activities of concern, using
performance information in Appendix G or
equivalent methods.
i
Step 2c
i
Identify a land management alternative or
combination of alternatives which will meet
the load reduction requirements.
)
r
Step 2d
Determine the capital and 0§M costs of land
management alternatives which meet perform-
ance requirements, using cost curves in
Appendix G or .equivalent methods.
>
f
/
Step 3a
/TABLE
j Item
6-6 /
1 /
6-6 /
2 /
6-6 /
2 /
^ /TABLE
y item
6-6 /
3 /
/TABLE
7 Item
6-6 /
4 /
6-85
-------
FIGURE 6-15 (CONTINUED)
LAND MANAGEMENT METHODOLOGY
FLOWCHART
Y
Determine Present- Worth cost of land manage- 1 Step 3b
ment alternatives using PRESENT-WORTH —
METHODOLOGY.
V
Identify the least cost land management Step 3c
approach. Record the Present-Worth cost '
and information reliability in Item 2 of
the FRAMEWORK METHODOLOGY WORKSHEET,
TABLE 6-3.
/TABLE 6-6 /
7 Item 5 /
/TABLE 6-3 /
7 Item 2 /.
T
(CONTINUE)
6-86
-------
TABLE 6-6
LAND MANAGEMENT 14ETHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgements presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all other
EPA, State, and local guidelines and regulations.
Land uses and land use activities of concern.
Land Uses and Waste load Applicable Land
Land Use Activities RODsK P TSS TCr Management Alternatives
Percent Reduction
BOD5 _N_ P TSS TC_
i) Load reduction requirements:
ii) Land management alternative performance capability.
Land Uses and Applicable Land Performance Range-Percent Reduction
Land'Use Activities Management Alternative BODs N P TSS TC
-See Table 6-7.
Most probable number/100 ml
By Date Strategy No.
Checked by Date Source No.
Remarks;
6-87
-------
TABLE 6-6 (continued)
LAND MANAGEMENT METHODOLOGY
WORKSHEET
Identification of alternatives which will achieve required reduction.
Land Uses and
Land Use Activities
Land Management Param-
Alternatives eter
. loadJ
[Perform- "JfWaste-
Lance CapaJ |_load Red
"]
.J
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-88
-------
TABLE 6-6 (continued)
LAND MANAGEMENT METHODOLOGY
WORKSHEET
| Item 4 j Capital and OfjH Cost (From Appendix G).
Land
Management Affected Land
Alternative Use/Activity (Acres) Capital Cost Of,?-! Cost
[ Item 5 | Present-Worth cost of land management alternatives.
Land Management Information Reliability
Alternatives Present-Worth Cost Performance Cost
From Appendix G
By Date Strategy No.
Checked hy Date Source No= _.
Remarks: . Page
6-89
-------
Notes on Methodology Logic
Step 1 - The various land uses and land use activities, and the pollutant
loads from these land uses and activities are identified using the Load As-
sessment Methodology of Chapters 2 and 3.
Step 2a - Land Management control alternatives applicable for controlling
land uses and activites of interest are listed in Table 6-7. The pollutants
which are significantly affected by the application of these control alterna-
tives to the land uses and activities listed are also presented in the table.
Further explanation of the nature, effectiveness, etc., of the various tech-
niques is presented in Appendix G, along with performance and cost informa-
tion.
Step 2d (Item 3) - In this step, the actual pollutant reductions which can be
expected by application of Land Management control alternatives to the land
uses and activities of concern are calculated. Based on the load-reduction
requirements recorded in Item 2, the user can identify a land use activity
for potential control. Based on the amount of reduction achieved by the
various Land Management control alternatives applied, if one alternative does
not produce the required reduction for any particular parameter, various com-
binations of alternatives can be considered. A combination which achieves
the required reductions for all parameters specified in the load-reduction
strategy should be selected. If more than one alternative or combination of
alternatives could be used to control a particular parameter or parameters,
both should be carried forward to the cost-determination steps in order to
choose the control alternative that would be most effective on the basis of
monetary cost.
6-90
-------
TABLE 6-7
LISTING OF LAND MANAGEMENT CONTROL ALTERNATIVES
APPLICABLE TO DIFFERENT LAND USES AND LAND USE ACTIVITIES1
Land Use or
Land Use Activity
High Density Residential
Medium Density Residential
Low Density Residential
Other Developed Areas
Commercial Areas
Industrial Sites
Landfill Sites
Hew Development
Applicable
Land Management
Control Alternatives
Street Sweeping
Street Sweeping
Sediment and Erosion
Control
Septic Tank Management
Sediment and Erosion
Control
Septic Tank Management
Sediment and Erosion
Control
Street Sweeping
Site Runoff Controls
Operation Regulations
Design Practices
Sediment and Erosion
Control
Zoning/Subdivision
Regulation
Site Design Restrictions
Principal
Pollutants Affected
BOD5 N_ P_ TSS TC_
X X
X X
X XXX
XXX X
X XXX
XX X
X XXX
X
X
X
X
X
X
XXX
X
X X
X X
X X X X
XXX
Limited to consideration of urban non-point sources.
6-91
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6,4,2,6 Collection System Control Methodology
Discussion
The purpose of investigating collection system control alternatives is to de-
termine whether such controls can reduce the runoff-pollutant load suffi-
ciently to meet the desired water quality objectives. These controls may be
employed to reduce the quantity of storm runoff which overflows to a stream
during a storm event, or to reduce the pollutant loading of this runoff.
Maximizing the use of the existing sewer system for storage of runoff will
reduce the volume of overflow which must be stored or treated external to the
system during the storm event. Also, this will enable the plant to handle
the storm runoff over a longer period of time, and thus reduce the occurrence
of overflows. Increasing the conveyance capability of the collection system
can reduce the frequency of overflows by making the system better able to
handle storm flows. Regular flushing of the sewer system helps to minimize
the accumulation of material which settles out of the dry-weather flow and
then is subject to scouring and discharge during the higher wet-weather
flows.
Existing data show that maximizing in-line storage and conveyance along with
the use of selective sewer flushing are effective techniques in reducing pol-
lution attributable to sewer overflows. In addition, their costs are minimal
compared to other control alternatives, and they should be seriously consid-
ered in situations where control of combined or storm sewer overflows is de-
sirable.
Other collection-system control alternatives are available. In some (e.g.,
catch-basin cleaning, improved sewer design and maintenance, inflow control),
the impact on alleviating overflow pollution is less certain than with the
techniques already mentioned. Others (sewer separation, sewer rehabilitation)
are partially effective, but are also much more costly. Information concern-
ing these control alternatives, as well as on those already discussed, is in-
cluded in Appendix G; both cost and performance data are presented where
available.
The intent of the COLLECTION SYSTEM CONTROL METHODOLOGY is to guide the user
in selecting control alternatives which have the best chance of providing
6-92
-------
significant pollution control at a minimum cost. Much of the cost and per-
formation on these alternatives is still being developed and thus
cannot be presented in this document. Where this is the case, or where as-
sessment or implementation methodologies are presented in current literature,
the highlights of the approach are presented here, and references are made to
specific documents for further information.
Methodology Logic
A summary of the logic of the COLLECTION SYSTEM CONTROL METHODOLOGY is pre-
sented in Figure 6-16. An expanded flowchart, Figure 6-17, lists the steps
to be taken in determining performance and costs. The worksheets for re-
cording the operations are presented as Table 6-8. Notes concerning the
methodology steps and worksheet items are presented after the worksheets.
6-93
-------
FIGURE 6-16
COLLECTION SYSTEM CONTROL METHODOLOGY
LOGIC SUMMARY
ENTER
Identify pertinent physical characteristics
and required pollutant control for sewer
segments causing water pollution problems.
i
Determine cost of utilizing ii
storage.
Step 1
t
i-line
Step 2
I Determine cost of sewer flushing.
j Step
Determine cost of polymer injection and
increased pumping capacity (fox surcharged
interceptors) at the existing plant.
Step 4
±
Consider other collection system controls. | Step 5J
Determine impact on runoff volumes and loads
of feasible collection system controls.
I Step 6
Determine Present-Worth Cost of
collection system controls.
| Step 7
c
CONTINUE
6-94
-------
FIGURE 6-17
COLLECTION SYSTEM CONTROL METHODOLOGY
FLOWCHART
f ENTER )
1
(
Identify existing sewer system characteristics
by drainage subarea (i.e., drainage area
tributary to an outfall).
i
Step la
t
Identify, critical sewer segments and required
control levels of pollutants for each subarea.
\
Step Ib
f
Consider a sewer segment.
i
Step Ic
f
Determine the amount of internal storage
available in the sewer system.
i
Step 2a
^ /TABLE 6-8 /
7 Item 1 /
/TABLE 6-8 /
•w/ , ,, /
J Item 2 J
^/TABLE 6-8 /
7 Item 3 /
f
Determine cost of utilizing available in-line
storage by installing control devices, using
Appendix G or an equivalent method.
i
Step. 2b
f
Identify elements within the sewer system
segment under consideration that may have
deposition problems.
i
Step 3a
f
Determine the impact of sewer flushing on
pollutant concentrations in overflows.
Step 3b
/TABLE 6-8 /
7 Item 4 /
/TABLE 6-8 /
7 item b /
/TABLE 6-8 /
V item 6 /
1
Determine the cost of sewer flushing using
Appendix G or an equivalent method.
\
f
Step 3c
/TABLE 6-8 /
7 Item 7 /
V
6-95
-------
FIGURE 6-17 (CONTINUED)
COLLECTION SYSTEM CONTROL METHODOLOGY
FLOWCHART
Have
all critical
sewer segments
been
considered?
Yes
Determine the cost of polymer inject
and increased pumping capacity (for
sewers) at the wastewater treatment
using Appendix G or an equivalent me
\
Consider other collection system con
as appropriate, using Appendix G or
equivalent method.
ion
surcharged
plant,
thod.
Step 4
f
trols
an
Step 5
^ /TABLE 6-8 /
7 Item 8 /
TABLE 6-8 /
/
7 Item 9 /
Determine the collective effect on r
volumes and loads of all collection
controls found to be feasible.
^
Determine the Present-Worth Cost of
system control using PRESENT-WORTH Ml
>
Record the Present-Worth cost and in
reliability for collection system co
Item 2 of FRAMEWORK METHODOLOGY WORK.
TABLE 6-3.
'
unoff
system
r
collection
ETHODOLOGY.
r
formation
ntrols in
SHEET,
f
Step 6
Step 7a
/TABLE 6-8 /
7 Item 10 /
!
/TABLE 6-8 /
7 Item 11 /
Step 7b
/TABLE 6-3 /
7 Item 2 /
(CONTINUE )
6-96
-------
TABLE 6-8
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not 1)6
interpreted as the .only approach available (or even as the preferred
approach). However, any approaches used should be consistent with
EPA Cost Effectiveness Analysis Guidelines and all other EPA, State
and local guidelines and regulations.
Item 11 Sewer System Characteristics.
Type of Overflow
Outfall Ho. Subarea Location1 Sewer Segment Type^ Control Device3
3
4
Locations should be referenced to a map using outfall and subarea numbers.
Combined sewer, storm sewer or unsewered.
Swirl separator or conventional regulator.
Py Date Strategy No.
Checked by Date Source No0
Remarks: Page
6-97
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Item 2 I Pollutants (BOD5, 'iSS, TC, P, :.'} to be controlled (from Load Reduction
Strategy .iatrix developed iu Chapter C.
Segment No. Pollutant Parameter Required % Reduction
[ Item 3 | In-line storage volume.
Hydraulic Dry Weather Internal
Segment No. Capacity Flow Storage Capacity
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-98
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Cost of utilizing available in-line storage from cost information
information in Appendix G, or an equivalent method.
Type of Construction 0§M Total Present
Segment No. Control1 Costs Cost Worth Costs2
Item 5 I Sewer segments with deposition problems.
Segment No. Extent of Problem Source of Problem3
Weir, gate, etc.
2Using PRESENT-WORTH METHODOLOGY
Obstructions, slack velocity, etc.
By
Checked by
Remarks i
Date
Date
Strategy No.
Source No,,
Page
6-99
-------
TABLE 6-3 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY '
WORKSHEET
I Item 6 Impact of sewer flushing on pollutant concentrations in overflows.
Pollufant Concentration
Outfall No. Segment No. Parameter Before After
Cost of sewer flushing using cost information in Appendix G, or an
equivalent method.
Segment No. OQM Total Present-Worth Costs
By Date Strategy No.
Checked by Date Source No.
Remarks'. Page
6-100
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Item 3 I Cost of measuring conveyance capability using cost curves in
Appendix G or an equivalent method.
i. Polymer injection costs.
Total Present-Worth
Segment No. Construction Costs OtjM Costs Costs
ii. Increased pumping capacity at the wastewater treatment plant where
influent interceptor is surcharged.
Existing Increased Construction OfTH Total Present-Worth
Capacity Capacity Cost Costs Costs ^
1Using PRESENT-WORTH METHODOLOGY
By Date Strategy No.
Checked by Date Source No,
Remarks'. Page
6-101
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Cost of other collection system controls as appropriate, using
Appendix G or an equivalent method.
Segnent No.
Type of
Control
Construction
Costs
OfJM Total Present-
Costs „• Worth Costs1
Using PRESENT-WORTH METHODOLOGY
By
Checked by
Remarks;
Date
Date
Strategy No.
Source No.
Page
6-102
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Iten 10[ Collective effect on runoff volumes and loads of all collection
systen controls found to be feasible.
Load
Control % Runoff Pollutant Reduction
Segment No. Alternative Controlled Parameter Achieved
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-103
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
[ Item llj Summary of feasible collection system control alternatives.
Collection System Control Present-Worth Costs
Total
By Date Strategy No.
Checked by Date Source No,,
Remarks; Page
6-104
-------
Notes on Methodology Logic
Step la (Item 1) - Pertinent sewer-system and drainage subarea character-
^k^™""""^"™^^™"^^^™™**^^^^™^^ *
istics are discussed in Section 3.4.4 (Chapter 3), including presentation of
a simulation technique for the assessment of storm loads and the effect of
control measures. The technique described in Section 3.4.4 is a summary of a
methodology presented in reference (2). The user is referred to this refer-
ence for more information on this simulation technique.
Step lb (Item 2) - Pollutants to be controlled and the degree of reduction re-
quired are specified in the Load-Reduction Strategy Matrix developed in Chap-
ter 6.
Step 2a (Item 5) - It is often possible to use the available internal storage
capacity of sewer systems more effectively by installing flow-regulation de-
vices to retain storm runoff or by routing runoff flows through the sewer sys-
tem so as to maximize detention time. The first step in attempting to reduce
the overflows by using these methods is to determine the hydraulic capacities
of existing sewer interceptors and the magnitude of the dry-weather flow.
The difference between these two values is an indication of the capacity in
the interceptor which might be available for internal storage. The planner
can use this information, along with information on slopes of the sewer lines,
to determine where the control devices could be placed to best utilize the
existing storage capacity. Detailed application of this alternative depends
on the specific area being examined and, thus, this methodology must remain
in general terms. Users are referred to references (2), (3), (4), (5), (6),
(7).
Step 2b (Item 4) - In most cases, the cost of in-line storage will be the
cost of installing regulator devices within the sewer system to utilize ex-
isting available capacity. For sophisticated systems, costs will also in-
clude remote-control instrumentation and automation.
Step 3a (Item 5) - Certain parts of a sewer system may be subject to the
settling of the solids contained in the dry-weather flow. In most cases,
this is because the slope is insufficient to maintain a velocity which will
keep the solids in suspension. These are candidates for a sewer-flushing
program which will remove the deposited material during dry-weather periods.
6-105
-------
This will help prevent later scouring of these solids, which adds to the pol-
lutant loading of the first flush during a storm.
Step 4 (Item 8) - The conveyance capability of a sewer system can be improved
by several methods, including polymer injection and increasing pumping ca-
pacity of the influent pump station where the interceptor to the plant is
surcharged. Polymer injection during storms into sewer segments subject to
surcharging can reduce hydraulic friction thus increasing carrying capacity
and possibly eliminating the surcharge condition. Also, increased pumping
rates at the head of a treatment plant in anticipation of a storm event will
create more capacity within the sewer system for conveyance and storage of
storm flows.
6-106
-------
6.4.2.7 Storage/Treatment Methodology
Discussion
The storage and treatment of combined and storm sewer overflows has received
much attention in recent years. New approaches and new technologies are be-
ing developed on a continuing basis. The feasibility, cost, and performance
of storage/treatment alternatives are in some cases unproven or uncertain,
and usually are highly dependent on site-specific factors, such as location
of overflow points in relation to existing interceptors and treatment facili-
ties, available capacity of wastewater treatment units and sludge handling
facilities, and rainfall and runoff characteristics.
The following methodology is presented: to aid the user in recognizing the
aspects of the problem that must be addressed; to provide available informa-
tion in some of the key factors to be considered; and to suggest alternative
approaches for handling sewer overflow problems by using storage and treat-
ment. Again, the user should keep in mind that the alternatives suggested
are not necessarily the only ones that might prove effective.
Storage/treatment control alternatives are the last resort in controlling
storm overflows. Because they usually involve the construction of facilities,
their cost is higher than the other wet-weather control alternatives. How-
ever, it is often necessary to resort to them, especially in large basins,
because it is difficult to control the large volumes of water and high pol-
lutant loads using land management or collection system controls alone.
For an understanding of the state-of-the-art in urban runoff pollution con-
trol technology and programs currently underway, the user should consult
pertinent EPA documents on urban runoff and urban stormwater management,
including references (8) and (9).
Methodology Logic
A summary of the methodology logic is presented in Figure 6-18. An expanded
flowchart, Figure 6-19, lists the steps to be taken in determining perfor-
mance and costs. The worksheets for recording the operations are presented
as Table 6-9. Notes concerning the methodology steps and work sheet items
are presented after the worksheets.
6-107
-------
FIGURE 6-13
STORAGE/TREATMENT METHODOLOGY
LOGIC SUMMARY
ENTER
Identify pertinent physical character-} Step
istics and pollutant control requirements
for sewer segments causing water pollution
problems through sewer overflows.
Ensure that appropriate col
system controls have been e1
'i
Investigate feasible storag
control alternatives and de
Present -Worth cost.
>
Investigate the potential f
zation of storage/treatment
cilities, and determine the
Worth cost of the regional
^
lection [
yaluated.
f
e/treatment 1
termine their
i
or regional i-1
fa-
Present-
alternatives.
t
Step 2
Step 3
Step 4
CONTINUE
6-108
-------
FIGURE 6-19
STORAGE/TREATMENT METHODOLOGY
FLOWCHART
C ENTER J
\
r
Identify existing sewer system characteristics
by drainage subarea (i.e., drainage area
tributary to an outfall).
\
Step la
t
Identify critical sewer segments and required
control levels of pollutant for each subarea.
i
Step Ib
i
Consider a sewer segment.
i
Step Ic
i
Ensure that appropriate steps have been taken to
maximize in-line storage and conveyance capability
of the sewer segment. If not, utilize the
COLLECTION SYSTEM CONTROL METHODOLOGY to determine
impact on runoff flows and loads.
Step 2
/TABLE 6-9 /
7 Item 1 /
/TABLE 6-9 /
7 Item 2 /
/TABLE 6-9 /
7 Item o /
Has the
load reduction
requirement
been
satisfied?
Identify feasible control options for each
segment based on sewer characteristics and site
specific considerations, using TABLE 6-10 or
other applicable reference information.
Step 3a
V
6-109
-------
FIGURE 6-19 (CONTINUED)
STORAGE/TREATMENT METHODOLOGY
FLOWCHART
Y
Determine Present-Worth Cost for each component
of each feasible option using the appropriate
worksheet Items C4-8) as listed in TABLE 6-10.
Step 3b
/TABLE 6-9 /
-7 Item 4-8 /
Summarize the Present-Worth Costs of storage
treatment components included in each option
and determine total Present-Worth cost for each
option.
Step 3c
Yes
CONTINUE
/TABLE 6-9 /
-y Item 9 /
Determine the potential for regionalization
of facilities, and determine the cost of
regional facilities using the REGIONALIZATION
METHODOLOGY. Record the Present -Worth cost
of these options in Item 10.
i
r
Record the Present Worth costs and informa-
tion reliability for storage/treatment control
alternatives from Items 9 and 10 in Item 2 of
FRAMEWORK METHODOLOGY WORKSHEET, TABLE 6-3.
i
t
Step 4a
Step 4b
•^.y
/
>/
/
/TABLE 6-9
Item 10
7
/TABLE 6-3
Item 2
/
/
6-110
-------
TABLE 6-9
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not
be interpreted as the only approach available (or even as the pre-
ferred approach). However, any approaches used should be consistent
with EPA Cost Effectiveness Analysis Guidelines and all other EPA,
State, and local guidelines and regulations.
Item 1 I Sewer System Characteristics.
t
Outfall Ko. Subarea Location1 Sewer Segment Type" Type of Control Device3 i
^Locations should be referenced to a map using Outfall and Subarea numbers.
^Combined sewer, storm sewer, or'unsewered.
^Swirl separator or conventional regulator.
Ey
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-111
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 2 j Pollutant Parameters (BOP5, TSS, TC, P, N).
Segment No. • Pollutant Parameter Required % Reduction
Item 3 Results of collection system controls.
i. Quantity of design storm runoff volume stored in internal storage of
collection system mg.
ii. Remaining runoff volumes and load:
Volume: mg.
Flow: mgd.
Load: mg/1 BOD,.
mg/1 TSS
mg/1 P
mg/1 N
ff/100 ml
By Date Strategy No.
Checked by Date Source No.
Remarks; Page
6-112
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 4 I i. Cost of Regulator, from information in Appendix G, or equivalent
' method.
Construction Cost $
0$M Cost $
Total Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY)
ii. Cost of swirl separator, using Table 6-11, or equivalent method.
Design flow
Construction Cost $
0$M Cost $
Total Present-Worth Cost S
(using PRESENT-WORTH METHODOLOGY)
Item 5 I Cost of storage tanks, from Table 6-11, or equivalent method.
Type of storage: Settling ^__ Complete mix
Construction Cost $
OSM Cost $
Total Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY)
By Date Strategy No.
Checked by Date Source No,
Remarks: Page
6-113
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 6
i.
Design Storri Characteristics.
Intensity in/hour
Duration hour
Frequency /year
ii.
M
NO'
Inlet hydrograph(s) for design storm (storm runoff entering the
sewer system) .
Method
Sub-are
TIME
rn
By
;a
FLOW
Sub -arc
TIME
;a
FLOW
Sub-are
TIME
;a
FLOW
: Plot hydrographs for each subarea on .separate sheets of graph paper.
Date
Checked by Date
Strategy No.
Source No.
Remarks;
Page
6-114
-------
TABLE 6-9 Ccontinued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
i Item 6 - Continued
iii. Inflow hydrograph to overflow-control structure.
Routing Procedure
TIME
FLOW
iv. Overflow hydrograph from the control structure.
(Attach rating curve for specific structure)
TIME
FLOW
By
Checked by
Remarks;
Date
Date
Strategy No.
Source No*
Page
6-115
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 6 - Continued
v. Mass Curve from Overflow hydrograph.
TIME
INCREMENTAL
VOLUME
CUMULATIVE
VOLUME
NOTE: Plot Mass Curve on separate sheet of standard graph paper.
vi. Storage/Treatment requirements.
% MAXIMUM
TREATMENT RATH
100
75
50
25
0
TREATMENT
RATE
STORAGE
VOLUME
0
By
Checked by
Remarks'.
Date
Date
Strategy No.
Source No,
Page
6-116
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 6 - Continued
vii. Cost of storage, using cost functions from Table 6-11, or equivalent
method, PRESENT-WORTH METHODOLOGY.
Type of storage .
Volume
to be
Stored Construction Cost Of,M Cost Present Worth Cost
NOTE: Plot Volume to be stored and Present Worth Cost.
Volume
By Date Strategy No.
Checked by Date Source No,,
Remarks'. Page
6-117
-------
TABLE 6-9 ([continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 6 ] - Continued
viii. Cost of on-site treatment, using cost functions from Table 6-11, or
equivalent method, and PRESENT-WORTH METHODOLOGY.
Treatment Unit
Treatment Rate Construction Cost
05M Cost
Present-Worth Cost
Treatment Unit
Treatment Rate
Construction Cost
OSM Cost
Present-Worth Cost
Treatment Unit
Treatment Rate
Construction Cost
0§M Cost
Present-Worth Cost
NOTE: Plot a cost curve for each type of treatment unit on the same set
of axes.
Treatment Rate
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-118
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 6 - Continued
ix. Cost of treatment at the existing plant.
a) Cost of discharging effluent to the interceptor and treating at
existing plant,
i. If interceptor is adjacent to overflow control device (as
in combined sewer), no cost is associated with discharge
to the interceptor.
ii. If interceptor is not adjacent to the overflow control device,
the cost to construct a sewer to transport the effluent can
be determined using the TRANSPORTATION COST METHODOLOGY and
PRESENT-WORTH METHODOLOGY.
Flow to be Transported Sewer Construction Present-Worth
and Treated Construction Cost 0§M Cost Cost
By Date Strategy No.
Checked by Date Source No,
Rema rks; Page
6-119
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
[ Item 6 I - Continued
b) Costs of upgrading/expanding existing treatment facility using
TREATMENT FACILITY METHODOLOGY and PRESENT-WORTH METHODOLOGY.
Treatment Construction
Rate Cost 0§M Cost Present-Worth Cost
c) Total Present-Worth cost of treatment at existing facility.
Total Present-Worth Cost of
Treatment Rate Transportation and Treatment
By Date Strategy No.
Checked by Date Source No»
Remarks: page
6-120
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
x. Least-cost combination of storage and treatment.
Treatment Least-cost Present-Worth Storage Present-Worth Total Present-
Rate Treatment Unit Cost of Treatment Volume Cost of Storage Worth Cost
iiOTE: Plot toal Present-Worth cost of storage and treatment versus
treatment rate.
Least-cost combination of storage and treatment.
S
By Date Strategy No.
Checked by Date Source No<>
Remarks'. Page
6-121
-------
TABLE 6-9 Ccontinued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
[item 7|
i. Cost of laying pipe to connect new regulator to existing outfall pipe
(if significant), or cost of laying a new or larger outfall pipe, from
cost' curve in Appendix H, Figure H-84 .
Construction Cost $
0§M Cost $
Total Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY)
ii. Cost of Disinfection (where required) from curve in Appendix H,
Figure 11-26.
Construction Cost $
O&M Cost $
Total Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY)
By Date Strategy No.
Checked by Date Source No»
Remarks: Page
6-122
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 8 | Cost of sludge handling.
On-site sludge handling.
a. Sludge treatment (using cost curves in Appendix II).
1) Organic sludges
Lime stabilization (Figure H-79)
Construction Cost $
0§M Cost $
Vacuum Filtration (Figure H-68)
Construction Cost $
05M Cost $
2) Inorganic sludges
Vacuum Filtration (Figure H-69)
Construction Cost $
0§M Cost $
3) Subtotal $
b. Sludge transport (using cost curves in Appendix H, Figures H-86
through H-90).
Method:
Construction Cost $
0§M Cost $
c. Sludge disposal (using cost curves in Appendix H, Figures H-81
through H-83J.
Method:
Construction Cost $
0§M Cost $
d. Total cost for on-site sludge handling.
Construction Cost $
0§M Cost $
e. Total Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY)
ii. Sludge handling at existing wastewater treatment facility.
a. Sludge transport to existing facility
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-123
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
I Item 8 I - Continued
1) If sewer is storm sewer, determine cost to construct sewer to
connect with sanitary sewer interceptor to treatment plant,
using TRANSPORTATION COST METHODOLOGY.
Construction Cost $
Cost $
2) If sewer is combined, existing interceptor capacity should be
sufficient to transport sludges to the existing wastewater
treatment plant.
b. Sludge treatment.
Determine if there is capacity available in existing sludge handling
facilities to accept additional sludge volumes from the treatment
of storm overflows. If not, determine cost to provide additional
sludge handling capacity at the existing facility, using TREATMENT
FACILITY METHODOLOGY.
Construction Cost $
0§M Cost $
c.. Sludge disposal (using cost curves in Appendix H, Figures H-81,
82, or 83).
• Method:
Construction Cost $
0§M Cost $
d. Total cost for sludge handling at existing wastewater treatment
facilities.
Construction Cost $
0§M Cost $
e. Total Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY)
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No<>
Page
6-124
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 9
Total Present Worth Cost.
Sewer Segment
Sewer Type
i. For each storage/treatment option, record the Present-Worth costs of
each component determined using Items 4-8.
ii. Determine the total Present -Worth cost of each option.
Present -Worth Cost (in $1,000)
*=
§
• H
t->
&
Regulator
i— i
M
•H
3
Storage w/
Settling
Storage w/
mixing
On-site WW
Treatment
Treatment at
Existing Plant
Interceptor
Construction
Disinfection
On-site Sludge
Handling
Sludge Handling
at Existing Plant
Total Present
Worth Cost
By
Date Strategy
No.
Checked by Date Source No0
Remarks;
Page
6-125
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 101 Regionalization of storage/treatment components, using
REGIONALIZATION METHODOLOGY.
Components regionalized:
Regional Facility:
Construction Cost $
0§M Cost $
Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY)
By Date Strategy No.
Checked by ~ Date Source No,
Remarks: Page
6-126
-------
Notes of Methodology Logic
Step la (Item 1) - Pertinent sewer system and drainage area characteristics
are discussed in Section 3.4.4 (Chapter 3), along with the presentation of a
simulation technique for the assessment of storm loads and of the effect of
control measures. The technique described in Section 3.4.4 is a summary of
a methodology presented in the EPA document on Development and Application of
a Simplified Stormwater Management Model (EPA-600/2-76-218). The user should
consult this reference for more information on this simulation technique.
Step. Ib (Item 2) - Pollutants to be controlled and the percentage reductions
required are specified in the Load-Reduction Strategy Matrix (illustrated for
the South River hypothetical example in Table 6-19).
Step 2a (Item 3) - The maximizing of storage and conveyance capability, as
well as other collection system controls such as sewer flushing, was de-
scribed in the COLLECTION SYSTEM CONTROL METHODOLOGY. It is mentioned again
here to emphasize the importance of this alternative in controlling wet-
weather flows. These alternatives are so effective in reducing sewer over-
flows, and have such relatively minor cost, that any consideration of
storing and treating sewer overflows should be considered in conjunction
with these collection-system controls. This step insures that the user
has considered these alternatives, and is using a load which has been modi-
fied to take into account the effect of the collection system. If the total
load-reduction requirement specified in the Load-Reduction Strategy Matrix
has been achieved using the collection system controls, the user need go no
further. If not, the user should continue with the STORAGE/TREATMENT
METHODOLOGY and consider various storage/treatment control alternatives.
Step 3a - The identification of feasible control options for storage and/or
treatment of sewer overflows should be based on the specific situation under
investigation. Choices must be made concerning: the type of regulator to be
used; the type and capacity of the storage device; the type, degree, and
location of treatment required; the type, capacity, and location of sludge-
handling facilities^ and numerous other factors. The following paragraphs
are provided to aid the user in addressing some of these decisions. This
discussion should be viewed as a guide only, and is not intended to be
6-127
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prescriptive in any way. Table 6-10 presents feasible combinations of the
storage/treatment components already mentioned, and lists the worksheet item
number which can be used to obtain a Present-Worth cost of the components
based on the flow and load information from Steps 1 and 2. The user should
consult the following discussion and other applicable references to aid in
determining which control option is applicable to his situation.
Flow Regulation - In determining the type of flow regulation to provide
at a sewer overflow location, it will be necessary first to determine the
types of regulators already in the system. Of course, storm sewers will not
have regulators, because the total flow in a storm sewer is discharged to
the receiving water. Combined sewers, in most cases, will have a conven-
tional type of regulator device of varying degrees of sophistication, rang-
ing from a simple weir to a dynamic device which has moving parts and can be
controlled from remote locations. However, a significant number of unattend-
ed regulators regularly malfunction because parts are frozen in an unde-
sirable position, or pieces are broken off, often allowing a continual dump-
ing of dry-weather flow to the receiving water. Thus, it is probable that a
new regulator device or repair of existing regulators will be necessary in
many cases.
The user may consider installing either a conventional regulator (which will
provide flow regulation alone) or a swirl regulator/separator device (which
will provide flow regulation plus solids removal). The swirl device can be
designed to provide solids separation up to a certain design flow and then
to bypass additional flows.
As far as the subsequent storage or treatment components are concerned, the
basic difference between the swirl separator and the conventional regulator
is that the swirl separator provides both an effluent flow (light fraction)
and a more concentrated underflow, one or both of which may be handled by
the storage/treatment components. The conventional regulator merely by-
passes those flows which are in excess of the hydraulic capacity of the
existing interceptor and/or wastewater treatment plant.
Storage - Off-line storage of the sewer overflow in the vicinity of the
overflow location can be either of two basic types: storage with settling,
6-128
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I
(-»
to
Control '
Storage/Treatment Worksheet ' Options
Components Item No. 1 2 3 4 5 6 7 8 9 10 II 12 13 14 IS • 16 17 18 19 20- 21 22 23 24 25
h
Q) Q>
1 0> X
« H
Regulation
Storage
IVastewater
Treatment
Overflow
Sludge
Handling
Combined
Sewer
Storm Sewer
Conventional
Regulator
Swirl
Separator
Storage with
Settling
Storage with
Complete Mix
On-Site High
Rate Treatment
Interceptor to
Existing Plant
And Treatment
Disinfection**/
Outfall
On-Site
Treatment
Interceptor to
Existing Plant
and Treatment
1
1
4
4
S
5
6
6
7
8
8
XXXXXXXXXX X
xxxxxxxxxxxxxx
xxxxx xxxxx
xxxxxx xxxxxxxxx
Es Es Or Or Ss Es Es Or Or
Es Es Es Or Or Or Ss Es Es Es Es Or Or Or
Em Em Em Em Em Em Et Et Em Em
Em Em Et* Em* Em* Em* ' Em*
Es Et Et Ed Ed Et Et Ed Ed Es Es Es Ed Ed Ed Ed Et Et Ed Ed
Ss, Ss,
St Sd St Sd St Sd Sd Ss St Sd
Ss, Ss, Ss*, Ss*,
Ss St Ss Ss Sd Ss St Sd Ss* Sd* Sd* -Ss* St* Sd*
Or = Regulator Overflow
Es = Swirl Separator Light Fraction
Et = Effluent from Settling Tank
Em = Effluent from Mix Tank
Ed = Effluent from Hi-Rate TCfT Device
Ss = Underflow from Swirl Separator
St = Settled Sludge
Sd i-Sludge from High-Rate Treatment
* May involve ..transportation of effluent or sludge
if storm overflow location is not near a sanitary
sewer interceptor.
** Disinfection is optional based on site specific
requirements.
a
i
i
CD
3
O\
8
o
f
O
2:
en
-------
and storage with complete mix. Any storage of storm overflows without spe-
cific provisions to keep the solids suspended will result in some settling
of the solids in the storage basin. The basin can be designed to remove the
solids and thus act as a primary settling tank. Alternatively, the solids
may be allowed to settle and other means of removing the solids may be em-
ployed, such as washing down the basin after the effluent is pumped out. De-
pending on the load-reduction requirements, storage with settling may provide
treatment sufficient to allow the effluent from the settling tank to be dis-
charged directly to the receiving water, with disinfection as the only other
treatment required. If not, the effluent must receive additional treatment.
Storage with complete mix is usually accomplished through mechanical mixers
or aerators. In most cases, the effluent from the complete-mix tank will
require additional treatment before discharge to the receiving water;
Occasionally the storage tank will need washing down after emptying to
avoid odor and solids-accumulation problems. This will depend in part on
the effectiveness of the mixers.
These two techniques can be used in conjunction. For example, a facility
in Milwaukee, Wisconsin was designed to allow settling during the storm
event, since there was a reasonable chance that the total storm runoff
volume entering the tank would exceed the tank's volumetric capacity.
By allowing settling during the storm flow condition, excessive flow that
might overflow the storage tank at least receives primary treatment by
sedimentation. After the storm, mechanical mixers are used within the
tank to resuspend settled solids as the tank contents are pumped out.
A benefit of having off-line storage facilities for wet-weather flows is
that these facilities may also be used for equalization of dry-weather flows.
Storage volumes provided 'for wet-weather flows will probably be more than
adequate, since only approximately 20 percent of the average dry-weather
flow is needed to provide equalization. The tank could be compartmentalized
to handle the smaller dry-weather storage in order to prevent solids from
this flow from spreading out over the whole tank.
Wastewater Treatment - Effluents from storage tanks may receive further
treatment in facilities provided at the overflow site, or may be transported
6-130
-------
through an interceptor to the existing wastewater treatment plant. The lo-
cation of treatment is selected by determining the least-cost mix of trans-
port and treatment. The tradeoff is between the size of the treatment units
plus cost of transportation, if necessary, and the size of the storage de-
vice. A treatment unit could be provided at the overflow site or at an ex-
isting plant that would treat the full flow expected during the storm event.
A smaller unit could be utilized if storage were also made available. Simi-
larly, the provision of storage capacity on-site might make the available
capacity at the existing plant sufficient to handle the storm flows. A sim-
plified approach to the storage/treatment optimization is provided in work-
sheet Item 6. The user can utilize this approach in the preliminary stages
of planning, but more detailed evaluation should be made as key decision
points are reached.
In determining the optimum mix of storage and treatment from a cost stand-
point, cost functions for both storage and treatment must be utilized.
Storage may be provided in the sewer lines themselves, or in a tank external
to the sewer system. Treatment may be provided at the overflow site by
utilizing a high-rate treatment unit, or at the existing treatment plant by
utilizing existing facilities or by expanding those facilities. The most
attractive combination of these options must be determined for each specific
situation. The cost of these options will depend on the degree of treat-
ment required, the excess capacity at the existing wastewater plant, the
availability of land at the overflow site for the construction of treat-
ment facilities, the availability of land at the existing wastewater treat-
ment plant site for expanding existing facilities, the sludge handling
ability at both sites, the opportunity to build an overflow treatment fa-
cility which would serve more than one outfall, and, in the case of the storm
sewer, the length of the connecting interceptor which must be constructed to
transport storm flows to the sanitary sewer interceptor leading to the exist-
ing plant.
As shown in Table 6-11, the 'swirl separator provides a degree of primary
treatment. The settling efficiency of a subsequent storage tank therefore
will be less for the swirl light fraction than for the overflow from a con-
ventional regulator because of the partial treatment already provided. Other
6-131
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TABLE 6-11
SUMMARY OF CONCENTRATION REDUCING TREATMENT
ALTERNATIVES FOR ON-SITE OVERFLOW TREATMENT DEVICES1'2
Detention Cost Functions-
(Annual Cost;$/yr)
1.
2.
3.
4.
5.
(%) Loading Rate
(gpm/ft.2)
TREATMENT BODq TSS N P FC Range
Microscreens 40-60 70 20
Screening/Dissolved 50-60 80 2.5
Air Flotation
Swirl Separator 25-60 50 60
High-Rate Filtration 60-80 90 24
Disinfection 99.9
Time Amortized Capital (CA)" 0 5 M TOTAL COST (TC)
(min) CA=lTm or CA=lSm OM=pTcl rC=sTz or TC=sS;
Range 1m p q s z
7,343.8 0.76 1,836.0 0.76 9,179.8 0.76
8,161.4 0.84 2,036.7 0.84 10,198.1 0.84
1,971.0 0.70 584.0 0.70 2,555.0 0.70
(See Appendix H, Figure H-26)
STORAGE
Storage with settling 25-40
(i.e., sedimentation)
Storage (high density
areas, 15 persons per acre)
Storage (low density
areas, 5 persons per acre)
55
0.5
Notes: T = Wet-Weather Treatment Rate in mgd; S = Storage Volume in mg.
2
100 mgd. No economies of scale beyond 100 mgd.
3 Reference (9).
Reference (10).
32,634.7 0.70 8,157.8 0.70 40,792.5 0.70
si,ooo.o i.oo
10,200.0 1.00
Amortized at 7% over 20 years.
ENR = 2000. Includes land costs, chlorination, sludge
handling, engineering, and contingencies. Additional COST
information for wet-weather storage and treatment devices
can be found in Appendix H, Figures H-17 through H-27.
-------
high-rate treatment units which may be considered for on-site treatment in-
clude those listed in Table 6-11, which gives ranges of treatment for various
pollutant parameters for each unit. Table 6-11 also includes cost informa-
tion for these high-rate processes or devices. In the case where an exist-
ing plant is to be expanded or upgraded to handle storm flows, the TREATMENT
FACILITY METHODOLOGY may be utilized to cost out the expansions/upgradings.
The on-site treatment units listed in Table 6-11 do not include biological
processes because of the difficulty of maintaining such a system with inter-
mittent flows. However, biological treatment of storm flows by expanding
existing biological plants is feasible, if an arrangement is made to provide
necessary activated sludge from the dry-weather flow units, or by routing
dry-weather flow through standby storm-flow units.
The user should consider providing the capability of increasing the loading
on the primary settling tanks at existing wastewater treatment facilities.
This may involve resetting the hydraulic regulators to allow more flow to
enter the treatment plant, or increasing the pumping capacity at the head
end of the treatment plant. This would accomplish several things. It would
provide the capability of working off the wet-weather flows stored in up-
stream storm flow storage tanks more rapidly. It would also allow the col-
lection system to be drawn down in order to provide more capacity for in-line
storage, as was discussed under the COLLECTION SYSTEM CONTROL METHODOLOGY.
The treatment efficiency of the primary settling tanks would be decreased,
but the overall increase in loading to the stream could be less than if over-
flows were made necessary because of storage capacity (in the lines or in
tanks) that was not available when the storm event occurred. Of course, it
would also be necessary to provide bypasses after the primary tanks in case
the secondary processes could not handle the increased flow.
Overflow - An overflow to the receiving water may come from a swirl
separator, a storage (with settling) tank, or an on-site high-rate treatment
unit. The user will want to make sure that the existing overflow line will
handle the quantity of overflow anticipated. If state or local standards re-
quire disinfection, the cost of providing this disinfection must be included
in the overall cost of the alternative.
6-133
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Sludge Handling - An underflow or sludge is generated at the overflow
site by a swirl separator, by storage with settling, or by on-site storm run-
off treatment. The sludge may be treated on-site or may be transported via
an interceptor to the existing wastewater treatment facility. Several sludge
treatment processes may be used to treat the sludges on-site, as listed in
worksheet Item 8. If this alternative is selected, provision must be made
for transporting the treated sludge to a final disposal site. If the swirl
separator or storage tank wastewater effluents are treated at the existing
plant, then, of course, the sludges will also be handled at the plant.
If the sludges generated on-site are discharged to the interceptor in order
to be treated at an existing wastewater treatment plant, several problems
may arise. The first is related to the transportation of the sludges to the
plant. The solids in storm flows are heavier than those in dry-weather flows,
because the velocity of the stormwater in the sewer is usually greater than
dry-weather velocities and will result in a scouring of previously deposited
heavy solids. These solids will tend to settle out unless sufficient veloc-
ity is maintained in the interceptor to keep them suspended. Therefore,
sections of the interceptor with marginal slopes might be subject to settling
problems. Another potential problem associated with either on-site or at-
plant treatment is the solids-handling capacity at the existing plant. For
example, it has been estimated by EPA that the sludge load at a particular
facility would be approximately doubled if combined sewer overflow sludges
are directed to the plant. Therefore, the alternative of discharging sludges
from sewer overflow storage and treatment components may include expanding
the sludge-handling capacities at the existing treatment facility. The ex-
cess capacity of these units should be investigated when costing out this
alternative. In addition, in the case of storm sewers it may be necessary
to construct an interceptor from the overflow site to the nearest sanitary
sewer interceptor in order to transport the sludges to the treatment plant.
A combination of the on-site and at-plant approaches is also feasible in
some cases. Grit removal can be provided on-site to alleviate, the heavy-
solids transportation problem, and the sludge dewatering and additional treat-
ment can take place at the existing wastewater treatment facility.
6-134
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Step 5b (Item 4) - If the existing regulator in a combined sewer is to be
replaced, or if a control device is to be installed in a storm sewer, the
cost of a conventional regulator or swirl separator is calculated by using
Table 6-11 or an equivalent method, and recorded in Item 4.
Step 5b (Item 5) - If the control option under consideration calls for on-
site storage and direct discharge to the receiving water (without treatment
either on-site or at the existing plant), Item 5 may be used for recording
the cost of settling. If treatment is to be provided, Item 6 should be
utilized in order to determine the least-cost combination of storage and
treatment.
Step 5b (Item 6'i) - Rainfall and stream flow are the driving forces behind
all storm flow investigations. Since storm patterns and rainfall character-
istics vary with geographic location, alternative methods of control must be
considered.
Storms of high intensity and short duration may be controlled effectively by
using storage facilities, whereas storms of low intensity and long duration
may be controlled more effectively through increased treatment capacity or
surface runoff deterrents. Intervals between storms are significant, because
they may dictate dewatering requirements and in turn control treatment rates
in a system clean-up between storms. Therefore, when dealing with storm
events, the important characteristics are the intensity and type of precipi-
tation, and the magnitude, frequency, and duration of the storm. These pa-
rameters may be determined by an investigation of rainfall records in the
area of interest, by utilizing parameters already determined for nearby areas,
or by any other appropriate method (see Chapter 3).
•
In order to determine the optimum (i.e., the least Present-Worth cost) mix of
high-rate treatment and storage of storm flows, it is necessary to develop a
hydrograph for the overflow from the control structure. Development of this
overflow hydrograph involves identification of a design storm frequency, de-
velopment of inlet (to the sewer system) hydrographs for the subarea tribu-
tary to an overflow structure, and use of a routing procedure to develop a
composite hydrograph of the inflow to the control structure.
6-135
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The design storm may be designated by a local drainage ordinance, or it may
be determined by means of an engineering analysis. The choice of a design
storm for a particular study area involves the following considerations:
• Timing of the rainfall and interval between events.
• Source data available.
• Scope and objectives of the investigation.
• Limitations of the physical system.
Engineering judgments relative to the most significant events for planning
purposes can usually be made from available data.
Step 3b (Item 6ii) - Using the design storm event and the physical character-
istics of the drainage area, the user must develop an inlet hydrograph for
runoff from the subarea tributary to each outfall. Numerous hand and com-
puter techniques are available for generating these hydrographs. The actual
method applicable in a specific situation is left to the user's discretion.
Step 5b (Item 6iii) - Having developed individual inlet hydrographs for each
subarea, the user must now route the time-dependent flows to the overflow
control structure in order to obtain a composite inflow hydrograph. During
the routing procedure, the user should take into account available in-line
storage capacity. The location and amount of available in-line storage can
be determined by using the COLLECTION SYSTEM CONTROL METHODOLOGY.
Step 5b (Item 6iv) - Using this inflow hydrograph and a rating curve (i.e.,
head versus discharge) for the structure, the user can generate an overflow
hydrograph.
Step 5b (Item 6v) - Assuming that all the overflow must be treated or stored
for subsequent treatment, the user can identify storage requirements nec-
essary for various treatment rates by using a mass curve developed directly
from the overflow hydrograph. The time-specific flows of the hydrograph are
converted to equivalent time-specific volumes and accumulated over the entire
time span of the hydrograph. The cumulative volume at time T is obtained by
taking the area under the overflow hydrograph to the left of time T. The
cumulative volumes are plotted versus time as shown in Figure 6-20.
6-136
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FIGURE 6-20
TYPICAL MASS DIAGRAM
-H
O -H
-i E
•H
4J T3
OS 0)
IS
1 S
UH
Time (liours)
n
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No«
Page
6-137
-------
Step 5b (Item 6vi) - Using the mass curve, the user can determine the storage
requirements for various treatment rates. The slope of the mass curve at any
time is a measure of the overflow rate. Treatment rates can be represented
by straight lines drawn from the origin. The storage volume required for a
specific treatment rate can be obtained by drawing two tangents to the mass
curve parallel to a desired treatment rate line and then measuring the ver-
tical distance between the two lines.
The peak overflow rate COM) occurs at the inflection point of the mass dia-
gram, which corresponds graphically to the maximum point on the inflow hydro-
graph. A treatment rate equal to the peak overflow rate would require no
storage facilities. This rate is represented by the line with slope TM
(TM = 0M). Lesser treatment rates would require storage of excess flows in
order to prevent overflows. For example, for treatment rate TN (T < TM),
storage SN is required to prevent overflow.
The user can use the mass diagram to determine the storage requirements for
treatment rates ranging from TM to no treatment, in convenient increments.
These combinations of storage and treatment are the bases for identifying
the least cost mix of storage and treatment.
Step 5b (Item 6vii) - The cost of the various levels of storage can be de-
termined using the appropriate equation from Table 6-11, or an equivalent
method. A plot should be made on standard graph paper of the volume to be
stored and of the Present-Worth cost of storing that volume.
Step 5b (Item 6viii) - Table 6-11 can be used to determine the high-rate
treatment units that can achieve the required load reductions. The cost of
these units for the various treatment rates can be calculated by using the
cost functions in Table 6-11. A plot of the cost of each type of unit for
the range of treatment rates should be made on standard graph paper.
Step 3b (Item 6ix) - The user must also determine the costs associated with
using existing wastewater treatment facilities in lieu of construction of
on-site facilities. The various options to consider are discussed under
Step 3a. The costs associated with treatment at the existing facility must
be determined for each rate of treatment, using the TREATMENT FACILITY
6-138
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METHODOLOGY when expansions or upgradings are necessary. The cost of trans-
portation and treatment at each rate of treatment should be plotted on the
same graph with the costs of on-site treatment (.Item 6viii).
Step 5b (Item 6x) - The cost curves plotted in Items 6viii and 6ix can be
used to determine the least-cost combination of storage and treatment rate
in the following manner:
• For each treatment rate, identify the least-cost treatment unit (high-
rate unit or existing plant expansion/upgrading from Item 6viii), and
record the treatment cost.
• Identify the necessary storage volume for each rate of treatment (from
Item 6vi), and1 record the cost of storage (from Item 6vii).
• Determine the total Present-Worth cost of storage and treatment for each
treatment rate.
• Plot total Present-Worth Cost versus Treatment Rate on standard graph
paper.
The minimum point on the curve will be the least-cost combination of storage
and treatment.
Step 4a (Item 10) - The user should investigate the potential advantages of
regionalization of storage/treatment facilities. Overflow locations are of-
ten in reasonably close proximity.
Depending on the specific situation, overflow points may be close enough to
make the use of one large storage tank (or treatment unit, or both) an
economical alternative.
\
6-139
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6.4.2.8 Wastewater Reuse Methodology
Discussion
The purpose of this component methodology,is to identify and evaluate po-
tential wastewater reuse opportunities for a specific point source. The
initial step is to identify whether there is a reuse potential in the plan-
ning area. When reuse seems feasible, the potential reuse candidates and
their water quality requirements are identified. The additional cost to
achieve a treatment level beyond that required for discharge, if necessary,
is evaluated by means of other component methodologies included in this
manual or equivalent methods. The wastewater transportation cost is also
identified, and the total cost for treatment and reuse is determined. The
reuser's cost for the existing water supply or the development cost for a
new supply is then determined and compared with the additional cost incurred
by the reuser for wastewater reuse. This evaluation will indicate if an
economic incentive exists for wastewater reuse, as indicated by a potential
saving to the reuser.
This methodology does not deal with pricing policies for wastewater reuse.
This is a specific consideration for any potential reuse application, and is
complex because of the interaction of supply and demand. However, the deter-
mination of the potential economic incentive for reuse accomplished in this
methodology should be adequate for identifying the potential for wastewater
reuse revenues.
Finally, this methodology can be readily modified to handle the case where
more than one reuser exists for a point source. The 208 planner or engineer
can do this by beginning his evaluation with the potential reuser who has
the most stringent water quality requirement. The wastewater from this alter-
native could then be used by any subsequent reuser in the planning area, so
that only the transportation cost would have to be computed. Another approach
would be to combine several potential reusers for one evaluation. By uti-
lizing these concepts, the 208 planner or engineer can readily develop the
cost associated with several reuse schemes and at the same time minimize his
effort in identifying treatment facility costs.
6-140
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Methodology Logic
A summary of Methodology Logic is presented in Figure 6-21. An expanded flow-
chart, Figure 6-22, lists the steps to be taken in determining performance and
costs. The worksheets for recording the operations are presented as Table
6-12. Notes on specific steps or worksheet items are included after the work-
sheet .
6-141
-------
FIGURE 6-21
WASTEWATER REUSE METHODOLOGY
LOGIC SUMMARY
ENTER
J
Identify the general potential for , j Step 1
wastewater reuse in the planning area. ~~""~~
*
Identify potential wastewater reusers | Step 2
or combinations of reusers.
Determine the Present-Worth costs of | Step
additional treatment associated with
wastewater reuse.
Determine the Present-Worth cost to I Step 4
the reuser of alternate supplies that
could be replaced by treated wastewater.
Identify specific reusers for whom j Step
incentive exists for wastewater reuse
(Present-Worth cost or non-monetary
cost).
(CONTINUE J
6-142
-------
FIGURE 6-22
WASTEWATER REUSE METHODOLOGY
FLOWCHART
C ENTER }
Identify wastewater reuse
planning area.
C "V
V^ CONTINUE J* No
i
r
potential in the Step 1
s' th
"*\. a r
^Xjpotei
Identify all major water users and ot
potential wastewater reusers in the
planning area. -
Consider a potential reuser or reuser
combination.
Identify the point source treatment 1
meet reuser water quality requirement
the effluent quality at the point sou
Identify wastewater treatment upgradi
required to meet reuser quality limit
introduction to Appendix H.)
Determine treatment cost
quality suitable for the
/TABLE 6-12 /
7 Item 1 /
sre ^X.
suse .S
^^
Yes
i
ler Step 2
'
Step 3a
i
eve Is to Step 3b
a.nd
rce.
1
ng Step 3c
(see
'
to upgrade effluent Step 3d
reuser.
•
!'
/TABLE 6-12 /
7 item 2 /
/TABLE 6-12 /
*y Item 3 /
/TABLE 6-12 /
7 Item 6 /
^/TABLE 6-12 /
J Item 4 /
\/
6-143
-------
FIGURE 6-22 (CONTINUED)
WASTEWATER REUSE METHODOLOGY
FLOWCHART
T
Determine the transportation cost to con
wastewater to the reuser,,
i
vey the
Step 3e
/TABLE
y Item
Identify the cost schedule for wastewater reuse
and the Present- Worth cost.
i
i
Determine cost to the reuser of present
supply that can be replaced by treated
wastewater.
i
i
Step 3f
/TABLE
7 Item
water
Step 4a
Identify the relative costs for wastewater
reuse compared to use of existing supplies
and other incentives for wastewater reuse.
t
Step 4b
/TABLE
7 Item
6-12 /
5 /
6-12 /
6 /
6-12 /
7 /
/TABLE
•y Item
6-12 /
8 /
Does a
monetary or
non-monetary in
centive exist
for waste-
ater reuse
Identify the reuser point-source combination
as an alternative for further consideration,,
Step 5a
Continue
Step 5b
/TABLE 6-12 /
-y Item 9 /
6-144
-------
FIGURE 6-22 (CONTINUED)
WASTEWATER REUSE METHODOLOGY
FLOWCHART
Yes
Is
there another
potential
euser?
Record Present-Worth cost and information
reliability for wastewater reuse in Item 2
of FRAMEWORK METHODOLOGY WORKSHEET,
TABLE 6-3.
c
CONTINUE
Step 5c
6-145
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not
be interpreted as the only approach available (or even as the pre-
ferred approach). However, any approach used should be consistent
with EPA Cost Effectiveness Analysis Guidelines and all other EPA,
State, and local guidelines and regulations.
Item l|- General Reuse Criteria.
i. Total municipal 'water demand approaching
existing water supply? YES NO
ii. Existing water supplies unavailable or
insufficient for new uses (e.g., irrigation,
industry)? YES NO
iii. Existing water supply subject to environ-
mental degradation (e.g., salt water
intrusion, aquifer drawdown)? YES NO
iv. Point source wastewater effluent available'
in sufficient quantity to satisfy potential
new needs? YES NO
v. Point source disposal technique involves
unusually high costs? YES NO
vi0 Planning area includes any large uses
of non-potable water? YES NO
vii. Absence of restrictions (riparian rights)
or related water law? YES NO
viii. Expressed interest on the part of
potential wastewater reusers? YES NO
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-146
-------
ON
1
4^
"^
ya o oo
3 (ft
01 O
;r- (B
U)
• o
Q.
O
HI
O
0)
t-t- *-»•
(B
tn
(/» 10
O i-t
C -1
-1 O>
0 rf
(B (D
O
O
Ol
(D
1 Item 2 | - Potential Reuse Source Identification
Potential Present Projected
Water Reuser Water Source/ Water Water Water Quantity Oualitv
Identification Treatment Use Cost Cost Current — n',' n v_ n . *S fr— •• „ ,. ....
^— ^— ^^— ^ ^—~~— — — — — ^uat- — ^-ost ^urrenT Design Yr Desired Minimum Reliability Distance
EXAMPLE:
'' KaMi~hell screened^ ^aJe"8 *°\12/1MO $0'24 »-4 m8d 1.4 mgd 76<>F 84<>F pH complete Smiles,
Plant Engineer ' - III?1,,..,*! Flint
minimum) River
p Farm rivate well, Irriga- $.08/1000 $0.22 400,000 No toxic same low 2 miles
Mr. Tom Young "° "" """^ tl0n pumping (May- lo^dis-
Owner cost Nov) solving
solids.
normal
pll
Albany County Private well, Irriga- $.14/1000 $0.38 300,000 700,000 some low 8 miles
Club no treatment tion gal gpd gpd -
pumping (May- (1!>80)
cost Nov)
1
ii
^ DO
S£
trd
^ & ON
O 1
50 W l-J
X ra NJ
en C
&%?
™g§
H r+
3 ti'
°s
O
*^
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
POTENTIAL REUSER EVALUATION
Reuser:
- Point Source Treatment to Meet Reuse Criteria .
Reuser Water
Quality Requirements
Existing Wastewater
Effluent Quality
Existing Wastewater
Effluent Quality
Control Criteria
Upgrade
Technique
Reference Cost
Curve
N/A
Reuser/Point Source Critical Parameters
Q
BOD
TSS
N
P
T
Identify the cost curve for upgrading each identified parameter to the reuser
criterion; identify the required system under "Reference Cost Curve" from
individual curves.
Item 4 - Treatment Requirement Cost Schedule to Meet Reuser Criteria.
(Use TREATftENT FACILITY METHODOLOGY to define costs for treatment above that
required for discharge)
Phase
Existing
Facility
1
2
3
n
Timing
Yr. to Yr.
Capital
0§M
Start
End
Replacement Cost
Year
Cost
Salvage
Value
By
Checked by
Rema rksi
Date
Date
Strategy No.
Source No.
Page
6-148
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
I Item 5 - Reuse Transportation Cost Schedule.
Phase
Existing
Facility
1
2
3
n
Timing
Yr. to Yr.
Capital
0§M
Start
End
Replacement Cost
Year
Cost
Salvage
Value
Item 6 - Wastewater Reuse Project Costs.
i. Project Cost Schedule.
Timing
Phase Yr to Yr
Capital Start End Variable Salvage
Item Cost OSM Of,M 0§M Value
#4
#5
TOTAL PHASE 1
#4
#5
TOTAL PHASE 2
#4
#5
TOTAL PHASE 3 ,
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No,
Page
6-149
-------
TABLE 6-12
WASTEWATER REUSE METHODOLOGY
WORKSHEET
- Wastevater Reuse Project Costs (continued).
Timing Capital Start "End Variable Salvage
Phase Yr to Yr Item Cost 0§M 0§M 05M Value
n £4
#5
TOTAL PHASE n
Replacement Schedule
Year Cost
ii. Present-Worth Cost (using PRESENT WORTH METHODOLOGY).
Interest %
Present-Worth Cost $
BY
Checked by
Remarks;
Date
Date
Strategy No.
Source No.
Page
6-150
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
[Item 7 | - Reuser Replaceable Water Costs.
(Cost that would be incurred for replaceable water supply without
wastewater recycle)
i.
Cost Schedule.
Phase
1
2
3
n
Timing
Yr to Yr
Recycle Water
Use1, gpd
Start
End
Unit Water
Cost2
$/1000 gal
Annual Water
Cost3, I/year
Start
End
11.
Recycle Water Use represents the portion of total reuser water
-requirement that could be satisfied by treated wastewater.
Unit Water Cost represents projected cost for existing supply if
adequate, or the unit'cost for development and treatment of a new
supply:
Annual Water Cost = (gpd) ($/gal) (365 days/yr)
Reuser Replaceable Water Present-Worth Cost.
(using PRESENT-WORTH METHODOLOGY): $
Item 8 - Wastewater Reuser Relative Costs.
i,, Replaceable Water Cost: $
(Alternative Present-Worth cost for reuser water needs that can be
satisfied during the planning period by treated wastewater;
from Item 7 ii)
ii. Reused Wastewater Cost: $
(Present-Worth cost to utilize treated wastewater; from Item 6 ii)
iii. Other Factors: (describe factors other than cost that will affect
further evaluation)
By
Checked by
Rema rks t
Date
Date
Strategy No.
Source No.
Page
6-151
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
[item 9 | - Potential Reuser/Point-Source Combinations
Point Source Reuser Identified Present-Worth Costs
Wa
ID
Q.mgd
ID
Q.mgd.
Wastewater
Reuse
Replaceable
Water
Non-Monetary
Total Cost Incentive
By
Checked by_
Remarks:
Date
Date
Strategy No.
Source No,
Page
6-152
-------
Notes on Methodology Logic
Step 1 (Item 1) - The purpose of this step is to determine if there is a reuse
potential in the planning area. This might occur where the available water
supply limits current or future water demand, where the existing water supply
will be subject to environmental degradation due to overuse or the impact of
the wastewater discharge, where the wastewater effluent is of a high quality,
or where wastewater disposal is unusually expensive. If any of the situations
identified in Item 1 exist, then the user of this manual should evaluate the
wastewater reuse potential further.
Step 2 (Item 2) - This step will identify the potential reusers in the plan-
ning area and also potential new uses fc... wastewater. A guideline is included
in Table 6-13, which identifies some potential reusers. The information for
each potential reuser is entered in Item 2. The information developed for
reuse of effluent from one point source in the planning area will likely be
applicable for the evaluation of wastewater reuse at other point sources.
Step 5a - No discussion.
Step 5b (Item 5) - The purpose of this step is to identify the required level
of treatment for utilization of the wastewater to supplement or replace the
reuser water supply. The critical water quality parameters for the specific
reuser should be identified in the worksheet as completely as possible. One
source for this information is reference
The existing wastewater discharge quality can be identified using the method
outlined in the TREATMENT FACILITY METHODOLOGY. Any additional treatment re-
quired to meet the reuser1 s needs is identified for each critical parameter.
If the required water quality for the reuser is not greater than that for
wastewater discharge, then there will not be an increased treatment cost.
Step 5c (Item 5) - In this step, the upgrading technique to meet the reuser 's
water quality requirements is determined. The user should incorporate in-
formation in Appendix H (or comparable sources) regarding the effluent char-
acteristics from alternative treatment processes.
Step 3d (Item 4) - This step identifies the treatment cost schedule for the
modification required to meet the reuser1 s water quality requirements. The
6-153
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TABLE 6-13
POTENTIAL CUSTOMERS AND APPLICATIONS
FOR WASTEWATER REUSE
Customer
Municipal
Applications
Irrigation
- Public parks, zoo grounds,
government centers, etc.
- Public golf courses
- School grounds
- Publicly-owned farm lands
- Right-of-way landscaping
- Other
Groundwater recharge
Prevention of salt water intrusion
Recreational lakes
Public utilities
- Cooling water for power plants
Cooling water
Boiler feed water
Process purposes
Irrigation of grounds
Crop irrigation
Salt leaching
Irrigation of
- Golf courses
- Duck clubs
- .Recreational areas, including
artificial lakes
*This list is not all inclusive; the individual planning agency should
develop a similar listing specific to the planning area.
Private Industry
Private Irrigation
6-154
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planner can utilize the TREATMENT FACILITY METHODOLOGY to determine the treat-
ment cost involved in attaining this level of treatment when a general
treatment facility upgrading is required. If only a portion of the wastewater
flow is utilized for reuse or if only one additional treatment operation is
required to upgrade the wastewater quality to meet the reuser's need, then the
capital cost can be developed using the TREATMENT FACILITY METHODOLOGY, or
an equivalent method, with the required adjustments for construction costs.
Step 5e (Item 5) - In this step, the transportation cost schedule for pumping
the required wastewater quantity to the reuser is determined by means of the
TRANSPORTATION COST METHODOLOGY.
Step 5f (Item 6) - In this step, the transportation and reuse treatment costs
schedules are combined to determine the total project cost schedule. The
project present-worth cost can be determined by means of the PRESENT-WORTH
METHODOLOGY.
Step 4a (Item 7) - In this step, the cost to the potential wastewater reuser
for replaceable water during the planning period is determined. The quantity
of replaceable water should represent the portion of the reuser's need that
can be satisfied by treated wastewater. Where the reuser's current supply
will be inadequate for future needs, the unit cost for developing and treating
a new supply should be used.
Step 4b (Item 8) - This step determines if there is an economic incentive for
wastewater reuse. Since a potential reuser would not be willing to pay more
for the treated wastewater than for the water supply currently used, the
maximum revenues from wastewater reuse to the treatment plant control author-
ity will always be less than this current water supply cost. Therefore, the
control authority will not find it cost-effective to pursue treatment and
• reuse where the reuse cost is greater than the current water supply cost,
unless other factors (such as a limited water supply) outweigh the monetary
cost considerations.
Step 5a - This step is a summary of the potentially cost effective point
source/reuser combinations. When the wastewater reuse evaluation has been
completed, this list will be useful in ordering priorities for future in-
vestigations and for assessing the overall potential for reuse.
6-155
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6.4.2.9 Impact Area Modification Methodology
Discussion
An impact area modification involves an alteration of the natural charac-
teristics of the receiving water body, such as in-stream reaeration, low-
flow augmentation, or a change in the physical location of a discharge point.
Reducing the impact of a pollutant discharge is sometimes less expensive than
reducing the pollution load in the discharge. This might also be the only
feasible alternative remaining if all feasible pollutant load reduction alter-
natives have already been implemented. In addition, this alternative may also
be especially applicable in certain streams where flow is highly regulated.
This component methodology will identify the monetary costs associated with
several modification schemes: discharge relocation, in-stream reaeration,
and flow augmentation.
The initial determination in this evaluation is the desired and critical water
quality of the receiving streams. These stream segments are commonly classi-
fied as: 1) Effluent Limited (implying that the control level is based on
the generally accepted treatment level); or 2) Water Quality Limited (which
means that the effluent control level has been based on a waste load alloca-
tion calculated as necessary to maintain the desired water quality). The
IMPACT AREA MODIFICATION METHODOLOGY is generally more often applicable to
Water Quality Limited stream segments, since these tend to have the more
stringent treatment requirements.
Discharge relocation is probably the most feasible of the impact area modifi-
cations in this evaluation procedure. The required procedure involves
identification of alternative discharge sites and evaluation of the points of
relocation. The water quality impact analysis techniques described in
Chapter 5 must be performed for the modified loading pattern to define the .
required treatment level at the proposed new location. Then, the costs of
treatment and transporation are computed.
\
In-stream reaeration will be a feasible technique only when the dissolved
oxygen in the receiving water is a critical water quality parameter and where
aeration is compatible with physical stream characteristics. Chapter 5 tech-
niques are required in this evaluation to redefine the source treatment
6-156
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level. Then, the cost to implement the reaeration system and the cost for
the modified treatment control level are evaluated.
Flow augmentation should be considered when water quality standards are vio-
lated during low-flow conditions, when means for flow augmentation (such
as an upstream reservoir) are available, and when low-flow augmentation
will alleviate one or more critical water quality parameters. The method-
ology guides the user in identifying the flow-augmentation capability in
determining the allowable waste loads with the flow augmented, and finally
in evaluating all project costs including treatment costs and flow-
augmentation costs.
The user should be advised that current EPA policy will not permit use of flow
augmentation as a substitute for "adequate treatment". See reference (19).
Thus, flow augmentation may only be considered where water quality standards
are not met through Best Available Technology (BAT) level of treatment. Even
where flow augmentation is warranted, the user should be aware of potential
institutional difficulties- in securing flow release guarantee agreements with
agencies controlling watercourses. The user should also consider potential
adverse effects of flow augmentation upon other uses of dams and reservoirs
(e.g., water-based recreation, water supply, power generation).
Methodology Logic
A summary of the logic of the IMPACT AREA MODIFICATION METHODOLOGY is pre-
sented in Figure 6-23. An expanded flowchart, Figure 6-24, lists the steps
to be taken in determining performance and costs. The worksheets for re-
cording the operations are presented as Table 6-14. Notes on specific steps
or worksheet items are presented after the worksheets.
6-157
-------
FIGURE 6-23
IMPACT AREA MODIFICATION METHODOLOGY
LOGIC SUMMARY
ENTER
Identify the source and the receiving
stream segment„
Step 1
Determine if Discharge Relocation is a
feasible control alternative.
Step 2
Determine if In-stream Reaeration is a
feasible control alternative.
Step 3
Determine if Flow Augmentation is a
feasible control alternative
Step 4
c
CONTINUE Y
6-158
-------
FIGURE 6-24
IMPACT AREA MODIFICATION METHODOLOGY
FLOWCHART
Consider a source and identify the receiving
stream water quality.
/TABLE 6-14 /
y Item 1 /
Go to Step 2h]No
Is
discharge
relocation
potentially
effective?
(See criteria in
Item 2).
Identify alternate discharge sites.
i
Step 2s
Consider a site.
Determine the level of treatmei
for discharge at the alternate
1
Step 21
it required
site.
Step 2c
/TABLE 6-14 /
*/ Item o /
/TABLE 6-14 /
y Item 4 /
6-159
-------
FIGURE 6-24 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
FLOWCHART
V
Determine transportation cost to relocate the
source discharge to the new site using TRANS-
PORTATION METHODOLOGY. -
Determine the modified treatment cost at
the alternate site using the TREATMENT
FACILITY METHODOLOGY.
Determine the Present-Worth cost of discharge*
relocation and a reduced level of treatment
using PRESENT-WORTH METHODOLOGY.
Continue.
[Step
2d
Step 2e
Step 2f
Is
there
another dis-
charge site for
evaluation?
Step 2g |
^/TABLE 6-14 /
~*lf Item 5 /
/TABLE 6-14 /
-y Item 6 /
/TABLE 6-14
Item
6-14 /
7 /
Continue.
i
Step
t
Identify the receiving body's critical
water quality parameters.
Step
2h
3a
>V
2_
/TABLE 6-14
J Item 8
7
V
6-160
-------
FIGURE 6-24 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
FLOWCHART
Determine the effect on stream DO of
increasing the source loading via the water
quality impact analysis techniques in Chapter 5.
>
Step 3b
i
Determine the cost of increasing stream
DO to the required level using artificial
reaeration.
i
i
Step 3c
Determine the treatment cost at the
reduced level of treatment.
i
Step 3d
/TABLE
7 Item
6-14 /
9 /
/TABLE
•7 Item
6-14 /
10 /
/TABLE
7 Item
Determine the total cost of using artificial
stream reaeration and calculate Present-Worth cost.
>
i
Step 3e
/TABLE
7 Item
Determine if the Water-Quality Limited
wastewater parameter control level is
^
i
Step 4a
/TABLE
7 Item
6-14 /
11 /
6-14 /
12 /
6-14 /
13 /
6-161
-------
FIGURE 6-24 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
FLOWCHART
Do
critical
water quality
conditions occur
at low
flow?
Determine the existing capability for low-flow
augmentation, and identify future capability.
i
'
Determine modified level of treatment for
the discharger, using the Chapter 5 water
quality impact analysis techniques at the
augmented flow condition.
i
Determine the cost to utilize flow
augmentation.
>
Record the Present -Worth cost and inf
reliability for feasible impact area i
tions on the FRAMEWORK METHODOLOGY WO
TABLE 6-3.
i
Step 4b
/TABLE 6-14 /
7 Item 14 /
Step 4c
f
ormation
modifica-
RKSHEET,
i
Step 4d
^/TABLE 6-14 /
7 Item IS /
/TABLE 6-14 /
7 Item 16 /
Step 4e
/TABLE 6-3 /
/ Item 2 /
(CONTINUE)
6-162'
-------
TABLE 6-14
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not be
interpreted as the only approach available (or even as the preferred
approach). However, any approach used should be consistent with EPA
Cost Effectiveness Analysis Guidelines"and all other EPA, State, and
local guidelines and regulations.
Item 1 - Receiving Water Quality.
Source
Water Quality Conditions: (Summary of existing and future water
quality problems by pollutant type for stream segment of interest)
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-163
-------
TABLE 6-14
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Discharge Relocation Evaluation.
Item 2| - General Criteria for Discharge Relocation.
1. Is this source a principal cause of the
critical stream condition? YES NO
2. Are there several significant sources
near this source? YES NO
3. Would relocation be relatively
inexpensive? YES NO
4. Is there a major Cor larger) stream
nearby that could receive the source? • YES NO
Item 5 - Alternate Discharge Site Identification.
(Factors: Less stringent water quality criteria; lower net
source loading; increased dilution due to tributary
flow)
Site Location Distance
a)
b) '
<0
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-164
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Site
Item 4|-
3
Evaluation
Modified Source Level
Level
Existing
Discharge
Site
Alternate
Discharge
Site A
Alternate
Discharge
Site B
Item 5 |-
Phase
Existing
Facility
1
2
3
n
By
.Checked
Remarks
Reference
Cost
Curve
of Treatment (from Impact Analysis, Chapter 5).
Parameter Control Levels
BOD
mg/1
COD
mg/1
TSS
mg/1
T-P
mg/1
NH3-N
mg/1
N03-N
mg/1
T-N
mg/1
T-C
#/ 100ml
Discharge Relocation Transportation Cost Schedule .
(use the TRANSPORTATION COST METHODOLOGY)
Timing
Yr. to Yr.
Capital
0§M
Start
End
Replacement Cost
Year
Cost
Salvage
Value
Date Strategy
b
y
No.
Date Source No.
Page
6-165
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOG?
WORKSHEET
Item 6\-
Phase
Existing
Facility
1
2
3
n
Item 7 |
i.
Phase
Existing
Facility
1
2
3
n
Modified Treatment Level Cost Schedule.
(use TREATMENT FACILITY METHODOLOGY)
Timing
Yr. to Yr.
Capital
dm
Start
End-
Replacement Cost
Year
Cost
Salvage
Value
- Project Cost.
Project Cost Schedule.
Timing
Yr. to Yr.
Capital
0$M
Start
ii. Project Present-Worth Cost: $
(use PRESENT-WORTMETHODOLOGK
By
Checked
Remarks
End
Replacement Cost
Year
Cost
r)
Salvage
Value
Date Strategy No.
hv Date Source No.
. — Page
6-166
-------
TABLE 6-14 (^CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
ARTIFICIAL REAERATION EVALUATION
Item 8\ - Receiving-Body Dissolved Oxygen Requirements.
Condition Dissolved Oxygen, mg/1
Water Quality Limit
Critical Level
Location
Item 9| - Modified Stream Quality at Revised Source Loads .
(developed from Impact Analysis, Chapter 5)
Wastewater Load
A.
B.
Parameter
BOD
TSS
(etc.)
BOD
TSS
(etc.)
Discharge Level
Resulting
Minimum Stream DO
Location
Item 10[- Artificial Reaeration Requirement.
i. Oxygen-Transfer Requirements.
Stream flow rate at critical conditions:
Critical DO level: mg/1
Minimum acceptable DO level:
Oxygen transfer requirement:
cfs
mg/1
Ib/hr for
_hr/yr
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-167
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Item
101
ii.
Phase
1
2
3
n
Item
- Artificial Reaeration Requirement (continued).
Reaeration Project Phasing.
Timing
Yr to Yr
Reaeration
Oxygen Demand, Ib/hr
Start End
ll| - Treatment. Cost Schedule at
Phase
Existing
Facility
1
2
3
n
Item
12|
i.
Phase
Existing
Facility
1
2
3
n
Timing
Yr. to Yr.
Capital
Capital
0$M
Start
End
Replacement Salvage
Cost Value
Moditied Treatment Level.
OW
Start
End
Replacement Cost
Year
Cost
Salvage
Value
- Artificial Reaeration Project Cost.
Project Cost Schedule.
Timing
Yr. to Yr.
Capital
0§M
Start
ii. Project Present-Worth Cost:
By
Checked
Remarks
Date
by Date
•
End
Replacement Cost
Year
$
Cost
Salvage
Value
Strategy No.
Source No.
Page
6-168
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
FLOW AUGMENTATION EVALUATION
[item 13| - General Applicability of Flow Augmentation as a feasible control
alternative.
Do critical water quality conditions occur at low flow?
(Yes or no) Critical Parameters, if yes; ^
Comments: (Special conditions, model assumptions, reference sheets)
[Item 14| - Flow-Augmentation Capability.
i. Existing Reservoir low-flow augmentation capacity:
Duration: days
ii. Proposed Reservoir low-flow augmentation capacity:
Duration: days
cfs
cfs
[Item 15| - Modified Source Load Control with Flow Augmentation.
i. Available Flow for Augmentation for the required
duration cfs
ii. Revised stream low flow
iii. Revised Level of Treatment
a)
b)
Critical Parameter
cfs
Revised Control Level
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-169
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Item 16|
i.
Phase
Existing
Facility
1
2
3
n
- Flow Augmentation Cost
Modified Level of Treatment Cost Schedule.
Timing
Yr. to Yr.
Capital
0§M
Start
End
Replacement Cost
Year
Cost
Salvage
Value
ii. Flow Augmentation Cost Schedule.
Phase
Existing
Facility
1
2
3
n
Timing
Yr. to Yr.
Capital
0§M
Start
End
Replacement Cost
Year
Cost
Salvage
Value
By
Checked
Remarks
Date Strategy No.
h Date Source No.
. y " Page
6-170
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
[Item 16| - Flow Augmentation Cost (continued).
iii. Project Cost Schedule.
Phase Year to Year
Total Phase 1
Total Phase 2
Total Phase 3
Total Phase n
Capital Sfart
Item Cost O&M
161
End
O&M
Variable
O&M
Salvage
Value
161
1611
161
1611
161
1611
Replacement Schedule
Year Cost
iv. Project Present-Worth cost.
Interest
Present-Worth Cost $
By
Checked by
Rema rks:
Date
Date
Strategy No.
Source No.
Page
6-171
-------
Notes on Methodology Logic^
Step 1 (Item 1) - This step of the evaluation will indicate if there might be
a monetary cost advantage for the use of an environmental modification with
the selected control alternatives. This will be indicated by the nature of
the control objective as indicated by the desired versus actual water quality
condition. This decision can be aided by determining whether the source load-
reduction identified for the strategy and for the source under consideration
is determined by the water quality standards of the receiving water (Water
Quality Limited) or treatment standards (Effluent Limited). If the segment
is Water Quality Limited, then modifying the impact of the discharge is more
likely to favorably alter the physical characteristic of the receiving water.
Step 2 (Item 2) - The relocation of the source load discharge point might be
feasible if another stream or other body of water near the discharge site has
less stringent water quality criteria than the proposed receiving water, or
if another location on the existing receiving water has a greater assimilative
capacity than the existing discharge site, etc., as described by general con-
ditions in this item. The user should note that unless there is a reduced
cost associated with treatment, the cost of transporting the treated source
effluent to the new discharge site will make discharge relocation an un-
attractive monetary cost alternative.
Step 2a, b, c (Items 3, 4) - The required level of treatment at the alternate
site should be evaluated utilizing the impact analysis in Chapter 5. If this
level of treatment is confirmed to be less than that required for discharge
at the existing site, then the costs associated with transportation and the
lower treatment level should be evaluated. A regionalized discharge also
could be considered.
Step 2d, e, f, g, h (Items 5, 6, 7) - The monetary cost associated with dis-
charge relocation for each identified alternative site is evaluated using the
appropriate methodologies.
Step 5a (Item 8) - Artificial stream reaeration will be a feasible alternative
when the water quality parameter of concern is the minimum D.O. of the re-
ceiving water. This information should be available from earlier deter-
minations (Item 1).
6-172
-------
Step 3b (Item 9) - Where the receiving water D.O. is the critical water qual-
ity parameter, it will be necessary to run the water quality impact analysis
in Chapter 5 using an increased wastewater source load to the receiving water
to define the effect on stream D.O. (Item 9). The D.O. deficit of the re-
ceiving water should therefore be defined using this modified load.
Step 5c (Item 10) - The monetary cost associated with artificial reaeration of
the receiving water is determined in Item 10. First, the oxygen deficit at
the critical point in the receiving water is calculated on the basis of the
stream flow rate at the model conditions, the minimum (critical) D.O. concen-
tration at the critical point, and the desired D.O. level at that point. The
required oxygen transfer can therefore be defined. In addition, the estimated
time that reaeration will be required should also be estimated. The cost for
artificial reaeration can then be computed utilizing site-specific informa-
tion.
Step 3d, e (Items 11, 12) - The treatment cost for the modified level of
treatment associated with the artificial reaeration evaluation should be
computed using the TREATMENT FACILITY METHODOLOGY. The Present-Worth cost of
the artificial reaeration alternative can then be evaluated using the PRESENT-
WORTH METHODOLOGY.
Step 4a (Item 15) - This step is used to determine if augmentation of the re-
ceiving water flow might be feasible as an alternative to the proposed level
of treatment for-the source. That is, if the source load level of treatment
is defined by the low-flow condition of the receiving water, then it might
be feasible to increase the allowable load of the critical parameters by
increasing the flow rate of the receiving water. Therefore, the first con-
dition that must be satisfied is that the critical parameter in the allow-
able level of discharge is determined by the low-flow condition of the re-
ceiving water (Item 4). This information should be available from the water
quality impact analysis of Chapter 5.
Step 4b, (Item 14) - Where flow augmentation could reduce the level of treat-
ment, the existing capability for low-flow augmentation must be identified.
This evaluation will require information on the available water supply up-
stream of the source discharge that can be used for low-flow augmentation.
6-173
-------
The assigned capacity for low-flow augmentation or the potential capacity for
this use should be identified as to the available rate of discharge and also
the length of time that this discharge can be maintained.
Step 4c (Item 15) - The low-flow rate in the receiving water should be modi-
fied to consider the flow available from the identified water supplies, and
the water quality impact analysis should be used to calculate the revised
level of treatment identified for the critical parameters.
Step 4d, e, f (Items 15, 16) - A revised treatment cost for this identified
level of treatment is developed using the appropriate methodology. The
Present-Worth cost of flow-augmentation alternatives can then be evaluated by
considering the monetary costs associated with utilizing the flow augmentation
capacity of the identified water supply and the treatment cost associated
with the reduced level of treatment.
The scope of this evaluation does not include consideration of the alter-
native of creating a water supply, especially for low-flow augmentation for
a specific wastewater source of interest. This alternative, however, could
be feasible in a specific case. For example, a situation where the natural
topography would lend itself to the creation of a reservoir might be a situ-
ation where a low-flow augmentation water supply could be readily developed.
6-174
-------
6.4.2.10 Regionalization Methodology
Discussion
The purpose of the REGIONALIZATION METHODOLOGY is to identify situations
where the monetary cost associated with a control alternative can be reduced
by handling two or more waste discharges at a common site. This methodology
will direct the user in evaluating regionalization of several wastewater
treatment facilities, as well as the utilization of a common disposal site
for several residual generators. However, the residuals disposal portion of
'this methodology is independent of the treatment portion; therefore, it can
and should be used independently.
The REGIONALIZATION METHODOLOGY guides the user in identifying feasible re-
gionalization combinations for wastewater treatment, and then determining the
cost associated with these combinations. Although generally applicable to
municipal point sources, regional!zation may include joint municipal-
industrial or cooperative-industrial treatment facilities. In the latter
case, the user would not estimate costs, but would be interested in effects
upon wasteload allocations and water quality.
Following the analysis of the wastewater source combinations, the user evalu-
ates the development of a regional residual disposal facility. This sequence
of steps (wastewater regionalization, residuals disposal combination) is
recommended since the residuals generated by a regional plant might differ
from those generated by the initially-identified, point-source control al-
ternatives .
Utilization of the REGIONALIZATION METHODOLOGY will be most effective when
the user is aware of the factors in the specific planning area that would
make a combination of several sources into one facility desirable. In most
cases, these will be both positive and negative effects from regionalization
which the user should consider. Typically, the greatest advantage of a re-
gional facility versus several smaller facilities is the economy of scale
associated with constructing, operating, and managing one large facility
rather than several smaller ones. Larger and more efficient operating budg-
ets, and efficient distribution and use of personnel are also benefits of
concentrating facilities and responsibilities for wastewater management.
6-175
-------
In some cases, however, savings in treatment plant construction may be offset
by increased collection system and operations and maintenance costs. In
evaluating regionalization alternatives, the user should also consider the
following potential effects:
1. Potential higher concentration of pollutants.
2. More pronounced consequences of treatment plant failures.
3. More sophisticated treatment plant which may be beyond local oper-
ating capabilities.
4. Inducement of urban growth along interceptor sewers.
Although many of the concerns are not specifically addressed in the REGIONALI-
ZATION METHODOLOGY, the user is encouraged to assess these effects in a
broader evaluation framework.
Perhaps the most important step in this REGIONALIZATION METHODOLOGY is the
identification of potential regional sites. It is' not the intent of this
manual to limit the user to identifying existing plants or disposal sites as
the only potential regional sites. Any tract of land that would be suitable
for a large wastewater treatment facility or disposal site should be evalu-
ated.
The treatment facilities (referred to as satellite facilities) that are com-
bined with the proposed regional site are important to the effective use of
the REGIONALIZATION METHODLOGY. Typically, the user would want to identify
combinations of regional and satellite facilities with higher individual
costs, since these combinations would have the greatest impact on the overall
alternative cost. However, the user should not limit his evaluation only to
the larger wastewater sources.
A decision step is included in this methodology relative to the identifi-
cation of additional regional/satellite combinations. This is included after
each combination has been evaluated to insure: first, that the user will not
have to identify every potential regional/satellite combination before deter-
mining the impact of these source combinations; and, secondly, to be certain
that the evaluation of regionalization continues until the reasonable combi-
nations have been evaluated. This decision step will require good judgment
6-176
-------
by the user who should utilize the trends apparent from the use of the
previous methodologies to evaluate the potential benefit from further combi-
nations. The user should continue these evaluations until the cost savings
cease.
In certain cases, even with demonstrable economies, regionalization may not
be locally acceptable. Therefore, as part of the evaluation process, the
user should be aware of attitudes concerning regionalization.
Methodology Logic
A summary of the logic of the REGIONALIZATION METHODOLOGY is presented in
Figure 6-25. An exapnded flowchart, Figure 6-26, lists the steps to be taken
in determining performance and costs. The worksheet for recording the oper-
ations is presented as Table 6-15. Notes on specific steps or worksheet items
are presented following the worksheets.
6-177
-------
FIGURE 6-25
REGIONALIZATION METHODOLOGY
LOGIC SUMMARY
C ENTER J
t
Identify potential regional sites for Step 1
wastewater treatment and feasible
regional/satellite combinations.
t
Determine level of treatment for a regional Step 2
facility.
t
Determine treatment cost for a regional Step 3
tacinty.
t
Determine cost to transport wastewater Step 4
from gattiiitt to r&ffionaJ^site.
- •---•--- f
Determine least Present-Worth cost of Step 5
alternatives tor regionalization of wastewater
treatment facilities.
t
Identify all residuals generators. Step 6
!
Identify the appropriate disposal methods Step 7
for each generator.
t
Identify potential regional residuals disposal Step 8
sites and feasible site/ generator combinations.
t
Determine residuals disposal costs. Step 9
¥
Determine Present-Worth cost of alternatives Step 10
for regionalization of residuals disposal sites.
*
( CONTINUE J
6-178
-------
FIGURE 6-26
REGIONALIZATION METHODOLOGY
FLOWCHART
^ ENTER ^
1
Identify ail continuous municipal pc
that are controlled in the load redi
int sources Step la
iction strategy. ™ -•
/TABLE 6-15 /
/ Item 1 /
V
Identify the sites in the planning
are potential regional wastewater f
sites.
area that Step Ib
reatment
\r
Identify potential regional site/sa
facility combinations.
bellite Step Ic
1 1
Consider a specific Regional/Satell.
combination.
ite Step 2a
i r
Determine the modified level of tre;
the Regional site based on the wate:
impact analysis techniques discusset
Chapter 5.
itment at Step 2b
r quality
i in
v
Determine treatment cost schedule fc
regional facility at the required It
control.
>r the Step 3
ivel of
> '
Determine the transportation cost sc
Regional! zation using the TRANSPORT;
METHODOLOGY.
:hedule for Step 4
VTION
1 1
Identify the project cost schedule •<
Present-Worth cost associated with 1
Regional/Satellite combination.
md Step 5a
:he
V
s
/TABLE 6-15 /
— / Item 2 /
/TABLE 6-15 /
/ Item 3 /
/TABLE 6-15 /
/ Item 4 /
/TABLE 6-15 /
— / Item 5 /
/TABLE 6-15 /
/ Item 6 /
/TABLE 6-15 /
/ Item 7 /
V
6-179
-------
FIGURE 6-26 (CONTINUED)
REGIONALIZATION METHODOLOGY
FLOWCHART
Record the Regional! zation project cost and
separate-source control cost for Regional/
Satellite combinations.
Step 5b
/TABLE 6-15 /
*j Item 8 f
Does this
evaluati on
suggest another
satellite combination
for this regional
site?
Is there
another
regional/satellite
combination that has bee
identified but not
evaluated?
Identify one or more attractive Regional/
Satellite combinations and reuse the Present-
Worth cost of these alternatives in Item 2 of
FRAMEWORK METHODOLOGY WORKSHEET, TABLE 6-3.
Identify all original residuals generators.
/TABLE 6-3
>/ Item 2
7
Step 6
/TABLE 6-
/ Item 9
y
\s
6-180
-------
FIGURE 6-26 (CONTINUED)
REGIONALIZATION METHODOLOGY
FLOWCHART
Identify
technique
Y
the residual quantity and dispc
for each generator.
Identify potential regional residual
methods and sites.
Identify
Consider
i
sal
Step 7
/TABLE
*y Item
disposal
1
t
Step 8a
/TABLE
regional site/generator combinations.
i
•
f
Step 8b
a regional site/generator combination.
i
t
Step 9a
Determine the Present-Worth cost for the
regional site/generator combination using
RESIDUALS DISPOSAL METHODOLOGY.
Identify
ated with
i
t
the residual disposal costs ass
the non- regional alternative „
Step 9b
oci-
Step lOa
/TABLE
•7 I Lem
6-15 /
9 /
6-15 /
10 /
6-15 /
H /
/TABLE
^7 Item
6-15 /
12 /
/TABLE
*1 Item
6-15 /
12 /
Does this
evaluation
suggest another
generator combination
for this regional
site?
6-181
-------
FIGURE 6-26 (CONTINUED)
REGIONALIZATION METHODOLOGY
FLOWCHART
Is there
another
regional site/
generator combination
that has been
identified but
ot evaluated?.
Identify one or more attractive regional/
satellite combinations and record the Present-
Worth cost and information reliability for
these alternatives in Item 2 of FRAMEWORK
METHODOLOGY WORKSHEET, TABLE 6-3.
Step lOb
/TABLE 6-3 /
-*/ Item 2 /
C
CONTINUE
6-182
-------
TABLE 6-15
REGIONALIZATION METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not be
interpreted as the only approach available (or even as the preferred
approach). However, any approach used should be consistent with EPA
Cost Effectiveness Analysis Guidelines and all other EPA, State, and
local guidelines and regulations.
Wastewater Treatment Regional Site Evaluation
- Source Identification.
(Attach topographic map with sources located)
Level of Control/
Source/Location Flow Critical Parameters
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
D
m)
n)
By Date Strategy No.
Checked by Date Source No.
Remarks: Pa9e_
6-183
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
jltem 2\- Regional Site Identification.
(Attach topographic map with sources located)
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
D
m)
n)
Available Estimated
Area Max. Flow
Site/Location (acres) "(mgd) Existing Condition
By Date Strategy No.
Checked by .Date Source No-
Remarks; Pa9e_
6-184
-------
TABLE 6-15 (continued)
REGIONA.LIZATION METHODOLOGY
WORKSHEET
Item 3 - Potential Regional Site/Source Combinations.
Combination
I.D. No.
1
2
3
Source 1
I.D.
Q (mgd)
Source 2
I.D.
Q Cmgd)
•
Regional Site
I.D.
Max
Site Q (mgd)
Max
Design Q Ogd)
By Date
Checked by Date
Rema rks :
Strategy No
Source No<>
•
Page
6-185
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
REGIONAL SITE EVALUATION
Regional Combination No.
|Item 4|- Level of Treatment at Regionalization Site.
Parameter Raw Wastewater Discharge Level
a)
b)
Level of Treatment
Level of Treatment:
|item 5|- Regional Site Wastewater Treatment Cost Schedule.
(Use the TREATMENT FACILITY METHODOLOGY)
Phase
Existing
Facility
1
2
3
n
Timing
Yr. to Yr.
Capital
OW
Start
End
Replacement Cost
Year
Cost
Salvage
Value
Item 6| - Wastewater Transportation Cost Schedule.
(Use the TRANSPORTATION COST JETHODOLOGY)
Phase
Existing
Facility
1
2
3
n
Timing
Yr. to Yr.
Capital
0§M
Start
End
Replacement Cost
Year
Cost
Salvage
Value
By
Checked by
Rema rks:
Date
Date
Strategy No.
Source No«
Page
6-186
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
I Item 71- Regional!zation Cost Evaluation.
i. Cost Schedule (Regional Combination No.
Phase
Timing
Yr to Yr
Item
# 5
# 6
Capital
Cost
Start
O&M
End
O&M
Variable
O&M
Salvage
Value
TOTAL PHASE 1
# 5
# 6
TOTAL PHASE 2
# 5
# 6
TOTAL PHASE 3
TOTAL PHASE 4
Replacement Schedule
Item Year Cost
ii. Present-Worth Project Cost: $
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-187
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TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
|Item 8 |- Present-Worth Cost.
Separate
Regional Source I.D. Treatment Costs Regional
Site I.D. No. 1 No. 2 Source 1 Source 2 Treatment Cost
By - Date Strategy No.
Checked by Date Source No.
Remarks: Pa9e_
6-188
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TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
Residuals Disposal Regional Site Evaluation
Item 9| - Residuals Generator Source Identification.
Residual Disposal Residual Characteristics
Source/Location Flow (mgd) Method Quality Type
a) :
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
1)
m)
n)
By Date Strategy No.
Checked by Date t Source No.
Remarks: Pa9e.
6-189
-------
TABLE 6-15 Continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
jltem 10] - Potential Residual Disposal Sites.
Available
Area Estimated
Site/Location (acres) Capacity Existing Condition
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
1)
m)
n)
By Date Strategy No.
Checked by Date Source No.
Remarks: : Pa9e_
6-190
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
Item 111- Potential Regional Site/Generator Combinations.
Regional Site Generator
Site I.D. Capacity I.D. Location Quantity
a.
b.
Item 12]- Regional Site/Generator Combined Present Worth Costs.
(Using the RESIDUALS DISPOSAL METHODOLOGY)
Combination Present Worth Cost
Generator I.D. at Combination Present Worth Cost Separate
a.
TOTAL
b.
TOTAL
By
Checked by
Rema rks :
Date
Date
Strategy No.
Source No.
Page
6-191
-------
Notes on Methodology Logic
Step la (Item 1) - The purpose of this step is to identify the wastewater
sources that are controlled in the strategy under consideration. The infor-
mation developed in this step should be useful in identifying the desired
source combinations for the separate regional facilitiy evaluations.
Step Ib (Item 2) - The potential regional sites are identified in this step.
There are numerous factors that will indicate a potential regional site in
the particular planning area. For the general condition, any existing waste-
water treatment site is a potential regional site, especially if there is
adequate room for expansion. However, it is not the intent to limit po-
tential regional sites to existing facilities; the user should attempt to
identify any suitable location in the planning area that satisfies the basic
requirements for a wastewater treatment facility. References should be con-
sulted for more information concerning facilities siting. For example, a
large undeveloped area lying in the proximity of several small treatment
sites might be identified as a potential regional site if it were at a lower
elevation than these sites. The information identified for the potential re-
gional sites should be recorded on the worksheet (Item 2) and should include:
the location of the site, the available area, the estimated maximum treatment
capacity (flow), and the existing condition of the site (e.g., existing
structures, utilities, roads, vegetation, etc.).
Step Ic (Item 5) - In identifying the source combinations for further study,
the proposed regional site is designated as the regional site, and the source
or sources that are to be relocated to the regional site are identified as
satellite sources. The worksheet is designed to evaluate two wastewater
sources combined at a regional treatment site, where the regional site can be
considered as one of the existing sources when desired. The user can evalu-
ate more complex situations by an iterative procedure utilizing these work-
sheets and by considering a regional site combination as one of the sources.
There is an opportunity later in the methodology to identify additional
regional/satellite combinations based on the results of the evaluation.
Step 2a - This step selects one of the combinations identified in Step Ic
(Item 3) for a detailed monetary cost evaluation.
6-192
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Step 2b (Item 4) - The water quality impact analysis techniques in Chapter 5
used to define the level of treatment required for each source must be modi-
fied to reflect the exclusion of the loads from the sources that have been
relocated to the regional site. The level of treatment required at the re-
gional site is then identified to maintain an acceptable water quality for
the receiving stream. When regionalization does not cause a significant
change in the pollutant loading pattern to the receiving body, the control
level for the regional facilities will be the same as that required at the
separate sources.
Step 5 (Item 5) - This step identifies the treatment cost schedule for the
regional facility. Several alternative treatment methods can be evaluated as
desired using the TREATMENT FACILITY and LAND APPLICATION METHODOLOGIES. The
worksheet is designed to present a summary of the selected treatment system
cost schedule.
Step 4 (Item 6) - This step identifies the wastewater transportation cost
schedule for the regionalization project. This can be developed using the
TRANSPORTATION COST METHODOLOGY and summarized in the Regionalization Work-
sheet.
Step 5a (Item 7) - This step presents the total project cost schedule. This
will include treatment costs (Item 5), transportation costs (Item 6), and
other special costs identified for the project. The PRESENT-WORTH METHOD-
OLOGY is used in this step to develop the Project Present-Worth cost.
Step 5b (Item 8) - This step summarizes the costs developed for the various
regionalization evaluations. The user can utilize Item 8 in identifying
control alternatives for further (non-monetary cost) evaluation. Following
the summarization of a regional cost, the user should determine if another
combination is suggested. This might involve the combination of two pre-
viously identified regional facilities into another larger regional facility.
This can be accomplished in Step Ic by identifying these regional facilities
as the satellite sites.
Step 6 (Item 9) - The purpose of this step is to inventory the residual
generators in the planning area. This identification should also include the
residuals generated in the wastewater regionalization evaluation. The
6-193
-------
characteristics of each residual should include the nature of the sludge
[biological or chemical) and the condition of the sludge (wet, cake, or ash)
as identified in the treatment system cost curves, as well as the general
area and disposal options available.
Step 7 (Item 9) - The purpose of this step is to identify the proposed dis-
posal methods for each of the residual generators as either land spreading or
landfilling. The usefulness of this inventory will be in later identifying
potential combinations for a specific regional disposal site. The quantity
of residuals from each generator should also be identified in this step.
Step 8a (Item 10) - In this step the potential regional residual disposal
sites are identified. This list, of course, should include all sites identi-
fied for the disposal of the individual point-source residuals. However,
this list should also include future sites that could be developed for a re-
gional residual disposal site; this is particularly important in evaluating
the regionalization of residual disposal sites since the capacity at the ex-
isting sites might limit regionalization potential. The characteristic of
the potential residual disposal sites should specifically address any con-
dition at the site that would enhance or limit its applicability for residual
disposal.
Step 8b (Item 11) - In this step the potential regional site/residual gener-
ator combinations are identified. In the first analysis of regionalization,
the user should identify the combinations that would have the most signifi-
cant impact on the monetary costs of the control strategy; typically, this
would indicate the larger quantities of residuals and those residuals with a
significant disposal cost. In addition, the user may wish to consider a
combination of a potential regional site with several residual generators.
This would allow the user to identify a common disposal site cost and the
individual residual transportation cost in one analysis, thereby saving
computational effort. The user should rely upon the experience obtained in
performing the individual residual disposal evaluations to identify these
combinations, as well as any local situation that would impact on a regional
residual disposal site.
6-194
-------
Step 9a - In this step the user selects a residual disposal combination for
the Present-Worth evaluation.
Step 9b (Item 12) - The Present Worth cost for the regional disposal site/
generator combination is evaluated in this step. This cost is developed
using the Residual Disposal Methodology and the combined residual charac-
teristics. The costs associated with the regional disposal site include the
site cost and the transportation cost for each residual to the site.
Step IQa (Item 12) - This step identifies the residual disposal costs deter-
mined when the separate disposal evaluations were performed. The regional
disposal cost can then be compared to the separate disposal cost to identify
relative monetary costs. This might suggest further residual combinations
for evaluation.
Step IQb - In this step the user identifies the least Present-Worth cost
residual disposal technique from the information summarized in Item 12.
6-195
-------
6.4.2.11 Present-Worth Methodology
Discussion
The purpose of this methodology is to determine the Present-Worth cost of an
alternative. The worksheet is designed to evaluate project cost schedules
developed by the evaluation procedures for each control alternative; it can
handle projects with up to four construction phases, but could readily be
modified to include more. The costs identified in the worksheet include
construction cost, constant and variable operation and maintenance (0 § M)
costs, existing facility phase out costs, facility replacement costs, and
facility salvage value. This procedure converts these costs over the project
life into an equivalent cost that represents the current investment that
would be required to satisfy all of the identified project costs for the
planning period. For a more detailed discussion, the user may consult any
standard engineering economy text, including reference(20).
The construction costs incurred by the project represent single-payment costs
that occur at certain times throughout the planning period. The single-
payment present-worth factor (sppwf) is used to determine the Present-Worth
cost, and is determined by the following formula:
s?Pwf = (i I i)n ' C6-1)
where:
i is the interest
n is the number of interest periods
The operation and maintenance (0 § M) cost includes both constant and vari-
able costs. The constant 0 § M cost is based on the flow rate at the be-
ginning of the planning period. The variable 0 § M cost represents the
difference between the 0 § M cost at the flow rate in the final year of the
planning period and the constant 0 £ M cost identified by the flow rate at
the beginning of the planning period.
6-196
-------
The uni form- series present-worth factor (uspwf) is used to convert the con-
stant annual 0 § M cost to a Present-Worth cost by the formula:
t C6-2)
where :
i is the interest rate
n is the number of interest periods
For cases where the constant payment is for a period that does not start at
the beginning of the planning period (Phase 2 constant 0 § M costs), the
uniform-series factor must be adjusted by multiplying it by the single- '
payment present -worth factor for the number of years from the beginning of
the planning period to the time that the constant payment begins, as in the
following:
(uspwf*1) x (sppwft2) - (6-3)
where:
tl is the number of years that the constant payment will be made
t2 is the number of years from the beginning of the planning period
to the time that the constant payment begins
The variable operation and maintenance costs are assumed to vary linearly
through the planning period and are multiplied by the gradient-series present
worth factor for the same number of years that the corresponding constant
operation and maintenance is paid (gspwfa-years) . This value is computed as:
[d * i)n - 1 1 -n[ 1 1
_Li (1 + i)" J 1(1 + i)"J
gspwf = *- " ^ ^ ^ •- ^ • -; j (6-4)
where:
i is the interest rate
n is the number of interest periods that the series is in effect
When using this term for computing the Present-Worth of a variable 0 § M cost,
care must be exercised to insure that the gradient 0 § M is used (i.e., the
annual average increase in 0 § M costs during the phase.
6-197
-------
If the gradient series does not start at the beginning of the planning period,
it must be adjusted by multiplying it by the single-payment present-worth
factor as follows:
(gspwf ) x Csppwf ) (6-5)
where:
tl is the period in which the gradient series is in effect
t2 is the number of years from the beginning of the planning period
to the time the variable payment is started
In practice, the user will find it more convenient to consult appropriate
tables in an engineering economy text; if tables are not available, the
preceding formulas will provide comparable results.
The facility replacement cost identifies the cost required to extend the use-
ful life of equipment to the end of the planning period. This is computed
when a cpaital item has a service life less than the remaining years in the
planning period, and is computed by:
_. .. . „ . Planning 'Period - Remaining Service Life „ . . w .
Replacement Cost = * Service Life x CaPltal Val"e,,
{.6-6J
where Capital Value represents the capital that would be required today to
completely replace the facility. This is a single-payment cost, with Present
Worth computed using the factor sppwf.
Finally, the salvage valve represents the value remaining for all capital at
the end of the planning period, and is computed by:
_ , „ , Service Life - Years to Planning End . ,, „
Salvage Value = Service Life * X Capltal (6-7)
where Capital (or Capital Value) represents the initial investment (or cost
to replace today). This is a negative cost, with the Present-Worth value
computed using the factor sppwf.
6-198
-------
Methodology Logic
A summary of the logic of the Present-Worth Methodology is presented in
Figure 6-27. An expanded flowchart, Figure 6-28, lists the steps to be taken
in determining performance and costs. The worksheet for recording the oper-
ations is presented as Table 6-16. Notes on specific steps or worksheet
items are presented following the worksheets.
6-199
-------
FIGURE 6-27
PRESENT-WORTH METHODOLOGY
LOGIC SUMMARY
ENTER
i.
j Identify basis for calculation.
Step 1
Identify capital cost components,
Step 2
Identify replacement costs.
Step 3
Identify project salvage value. Step 4
IIdentify 0 § M cost components
CONTINUE
)
| Step 5 {
Determine project
>
f
Present -Worth cost. Step 6~
>
t
6-200
-------
FIGURE 6-28
PRESENT-WORTH METHODOLOGY
FLOWCHART
ENTER
L
Identify interest rate Step 1
for calculation. "" """
V
Identify capital cost | Step 2
for each facility phase.
•^ i
*/
/TABLE 6-16
Items 1,2,3,4
I Determine replacement costs.
I Step 3 I /TABLE 6-16 /
/ Items 5"9 /
Determine salvage value at
end of planning period.
| Step 4 / TABLE 6-16 /
/ Item 10 /
Determine constant 0 § M
costs for each phase.
Determine variable 0 § M
associated with the increment
in flow during, each phase.
I Step 5a I / TABLE 6-16~7
I—*/ Items 11,13,15,17 /
/TABLE 6-16 7
-y Items 12,14,16,18 /
Step 5b
Determine Present-Worth for
component costs using the
appropriate Present-Worth
factors.
Step 6a
/TABLE 6-16 /
-*/ Items 2-18 /
Determine total Present-Worth Step 6b
cost by summing component Present-
Worth costs.
/ TABLE 6-16 /
"*/ Item 19 /
c
CONTINUE
6-201
-------
TABLE 6-16
PRESENT-WORTH METHODOLOGY -
WORKSHEET
The procedures, calculations, assumptions, and judgements presented
in the flowcharts and worksheets are for guidance only, and should
1 not be interpreted as the only approach-available (or even as the
preferred approach) . However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and
Items 1-10 | Present -Worth
Planning Period 20 years
Item (Reference Page)
1. Phase 1 Capital
(Pg. )
2. Phase 2 Capital
(pg. )
3. Phase 3 Capital
(pg. )
4. Phase n Capital
(Pg. )
5. Replacement year (h)
(Pg. )
6. Replacement year (i)
(pg. )
7. Replacement year (j)
(Pg. )
8. Replacement year (k)
(pg. )
9. Replacement year (1]
(pg. )
10. Salvage Value
(Negative Cost)
(pg. )
By
Checked by
Remarks:
local guidelines and regulations.
Calculation.
Interest %
Amount Present-Worth
x 1.0
(Yr 1)
x (sppwfa)
(Yr )
x (sppwf )
(Yr )
x (sppwfc)
(Yr )
x (sppwf11)
(Yr )
x (sppwf1)
(Yr )
x (sppwf j)
(Yr )
x (sppwf )
(Yr )
x (sppwf1)
(Yr )
x (sppwf2')
(Yr )
Date Strategy No.
Date Source No.
Page
6-202
-------
TABLE 6-16 (continued)
PRESENT-WORTH METHODOLOGY
WORKSHEET
Item 11-19 Present-Worth
Planning Period 20 years
Item (Reference Page)
11. 0§M Phase 1 Constant
(Pg- )
12. 0§M Phase 1 Variable
(Pg. )
13. 0§M Phase 2 Constant
(PS- D
14. 05M Phase 2 Variable
(Pg. )
15. 0§M Phase 3 Constant
(pg. D
16. OSM Phase 3 Variable
(pg. D
17. 0§M Phase n Constant
(Pg. )
18. 0§M Phase n Variable
(Pg. )
19.
By , Date
Checked by Date
Remarks:
Calculation.,
Interest %
Amount Present-Worth
x (uspwfd) x 1.0
(#Yrs jYr 1)
x (gspwf ) x 1.0
(#Yrs ;Yr 1)
x (uspwfe x sppwf8)
(#Yrs ;Yr )
x (gspwf6 x sppwfa)
(#Yrs ;Yr )
x (uspwf x sppwf )
(#Yrs ;Yr )
x (gspwf x sppwf )
(#Yrs ;Yr )
x (uspwf^ x sppwf0)
(#Yrs ;Yr ~)
x ( gspwf g x sppwf0)
(#Yrs ;Yr )
TOTAL PRESENT-WORTH $
Strategy No.
Source No.
Page
6-203
-------
Notes on Methodology Logic
Step 1 - The rate of interest should be selected to realistically reflect the
prevailing interest rates and inflationary trends. The actual interest rate
which must be used is published annually by the U.S. Water Resources Council
18 CFR 704.39, Discount Rate, Federal Register published annually. The
interest rate selected should be the same for each alternative.
Step 2 (Items 1, 2, 3, 4) - The capital cost for each phase will be available
from the project cost schedule. The timing for each capital investment and
all other costs should be recorded on the worksheet in (Yr ), with the
page number of the calculation recorded in (pg. ). The superscripts (a,
b, c, etc.) are for reference purposes to aid in identifying the factors that
are identical.
Step 3 (Items 5, 6, 1, 8, 9) - The replacement cost schedule will be available
from the project cost schedule.
Step 4 (Item 10) - The project salvage value for all capital expenditure will
be available from the project cost schedule, and represents a negative cost at
the end of the period.
Step 5a (Items 11, 13, 15, 17) - The constant 0 § M costs will be available
from the project cost schedule.
Step 5b (Items 12, 14, 16, 18) - The variable 0 § M costs will be available
from the project cost schedule or can be computed using:
Variable 0 £ M _ Constant 0 § M (Phase 2) - Constant 0 5 M (Phase I)
(Phase 1) Years in Phase 1
Step 6a (Items 2 to 18) - The required Present-Worth factors will generally be
available from standard tables. If the required interest rate is not identi-
fied in the tables, these factors can be computed using the formulas described
in the general discussion section.
I
Step 6b (Item 19) - The Present-Worth is determined by adding the separate
Present-Worth costs and subtracting the Present-Worth of the salvage value.
6-204
-------
6.4.2.12 Residuals Disposal Methodology
Discussion
The purpose of this methodology is to identify costs associated with disposing
of the residuals generated by a wastewater treatment process. The TREATMENT
FACILITY METHODOLOGY identifies residual handling and treatment costs as well
as the wastewater treatment costs; therefore, this methodology will identify
only the costs associated with transporting the treated residuals to the dis-
posal site and with disposing of the residuals at the site.
This methodology includes two ultimate disposal alternatives for wastewater
treatment residues: land spreading or landfilling. These disposal techniques
are similar in their transportation requirements and are the most widely used
techniques at this time. However, there is no intent to limit the user to
evaluation of these alternatives only. For discussion of other residuals
handling techniques, the user should consult references(21-24). There may be
opportunities for cost-effective disposal of wastes that would apply only to
a specific locality, such as an abandoned mine. The user is encouraged to
seek a local solution to his disposal problem. Even if the alternatives
other than the two suggested above are considered, parts of this methodology
can serve as guidance in determining costs. Evaluation of residuals disposal
practices must include consideration of local attitudes, potential socio-
economic effects, and public health implications.
Methodology Logic
A summary of the logic of the RESIDUAL DISPOSAL METHODOLOGY is presented in
Figure 6-29. An expanded flowchart, Figure 6-30, lists the steps to be taken
in determining performance and costs. The worksheet for recording the oper-
ations is presented in Table 6-17. Notes on specific steps and worksheet
items are included after the worksheets.
6-205
-------
FIGURE 6-29
RESIDUALS DISPOSAL METHODOLOGY
LOGIC SUMMARY
f ENTER ^
i
f
Determine the appropriate residual
disposal alternative.
i
r
Identify disposal site.
i
f
Determine cost for disposal site.
>
f
Determine disposal costs.
1
Determine transportation costs.
1
Determine Present-Worth cost
of residual disposal.
^
r
( CONTINUE J
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
6-206
-------
FIGURE 6-30
RESIDUALS DISPOSAL METHODOLOGY
FLOWCHART
ENTER
Identify the type of residual according to the
wastewater treatment process.
Step la
/TABLE 6-17 /
-y Item 1 /
Determine the disposal method.
I Step Ib /TABLE 6-17 /
J '—y Item 1 /
Determine the quantity of residual for
disposal.
Step Ic
I Identify existing disposal sites.
/TABLE 6-17 /
-y Item 1 /
{ Step 2aj /TABLE 6-17
V Item 2
/
/
Identify potential new disposal sites.
| Step 2b | /TABLE 6-17 /
7 Item 2 /
I Determine the capacity of the disposal sites. I Step 2c I /TABLE 6-17 /
1 ] ' ' 7 Item 2 /
Consider a disposal site.
Step 3a
6-207
-------
FIGURE 6-30 (continued)
RESIDUALS DISPOSAL METHODOLOGY
FLOWCHART
Determine the cost for developing this
to dispose of the residual using the a
propriate cost curve from Appendix H:
Sludge Landfilling, Land Application o
Sludge, or an equivalent method.
\
Go to Step 5
site
ip-
f
Step 3b
V
Determine the residual disposal cost f
the user charge for the existing site.
i
rom
Step 4
/TABLE 6-17 /
*y Item o /
/TABLE 6-17 /
j Item 4 /
/
Determine the residual transportation cost
schedule of utilizing the disposal site using
appropriate cost curves in Appendix H or
their equivalent.
Step 5
/TABLE 6-17 /
•y Item o j
Determine the Present-Worth cost of the
disposal site using PRESENT-WORTH
METHODOLOGY.
Step 6a
/TABLE 6-17 /
-y Item 6 /
6-208
-------
FIGURE 6-30 (continued)
RESIDUALS DISPOSAL METHODOLOGY
FLOWCHART
No
Summarize the Present -Worth cost of all Step 6b
residual disposal site/generator
combinations .
»
Identify the cost schedule for the Step 6c
disposal scheme and transfer the cost to
the appropriate methodology (i.e., the
component methodology for which the
residual disposal cost is being deter-
mined for the source under consideration) .
•^j
/
/TABLE 6-17 /
y Item 7 /
CONTINUE
)
6-209
-------
TABLE 6-17
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as" the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
Item 1|- Residual.Characteristics.
i. Residual generator method of treatment:
ii. Residual description:
iii. Feasible disposal techniques:
IV. Residual quantity: (ultimate)
Design Year Flow Rate mgd
Residual Generation Ib/mgd (dry basis)
Disposal Quantity Ib/day (dry basis)
Item 2| - Residual Disposal Sites.
i. Site characteristics summary.
Distance Estimated
from Useful
Site Location Generator Capacity Comments
a) Existing Land
Spreading Sites.
b) Existing Landfill
Sites.
c) Potential Sites.
i) Landfill.
ii) -Land Spreading.
By
Checked by
Rema rks :
Date
Date
Strategy .No.
Source No»
Page
6-210
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
Item 2[- continued
iii. Site capacity evaluation - existing site
a) Useful life at existing disposal rate: years
b) Existing disposal rate: Ib/day or ton/day or
cu yd/day
C) Proposed disposal rate: (same units as above)
(use average rate for entire planning period)
d) Useful life at proposed disposal rate = (a) x -^- =
By Date Strategy No.
Checked by Date Source No.
Remarks:
6-211
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
Item 3
i
ii
Land
2Land
- Cost for Development of Residual Disposal Site.
. Program Schedule.
Phase Timing Design Flows (mgd)
1
2
3
n
Yr to Y£
to
to
to
to
Start End
Site Development Schedule.
Design 1 2
Phase Flow Land Required ' Land Cost
1
2
3
n
Required =
Cost = $
(mgd) (acre)
acre/mgd
/acre
iii. Project Cost Schedule - Disposal Site.
Phase
Land
Cost
1
2
3
n
Timing
Yr to Yr
, 0§M
Capital Start End
Replacement Cost Salvage
Year Cost Value2
Capital computed as described for TREATMENT FACILITY METHODOLOGY; includes con-
struction add on's to reflect installed capital. Capital = curve $ x (1.0 +
Construction Add on's.)
Cost computed as described for TREATMENT FACILITY METHODOLOGY; attach appro-
priate computations.
By
Check
Remar
ed by
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
Item i
• - Residual Disposal Cost
for Existing 'Site.
Program Costs
Timing Design Flow (mgd) Residual Quantity1 Disposal Cost2
Phase Yr
1
2
3
n
1Dete
2Dete
Item I
'•> - P
A
i.
to Yr Start
rmined using
rmined using ($
End
Start End Start End
Ib/mg
/lb disposal cost) x (Residual
Quantity Ib/yr)
.esidual Transportation Cost (using appropriate cost curves in
ppendix H, Figures H-86 to H-90, or equivalent.
Transportation Method:
Residual Characteristics: Type Solids
Phase
1
2
3
n
ii.
Transportation Cost Schedule.
Timing
Yr to Yr
Capital1
os
Start
H
End
Design
Start
Flow Replacement C
End Year Cos
Develop capital estimate based on end design flow for each
include construction add on's to reflect installed cost.
2
Develop 0§M estimate (start and end) for each phase.
By
Date
Checked by
Rema rks :
Date
Strategy No.
Source No.
ost Salvage
t Value
phase ;
Page
6-213
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
Item 6)- Residual Disposal Site Present-Worth Cost
i. Alternative Characteristics:
Residual
Solids .
Transportation Method
Disposal Method
ii. Present-Worth Cost
(from PRESENT-WORTH METHODOLOGY)
Reference Sheets
Item 7|- Site Alternatives Summary - Residuals Disposal
Site Location Present-Worth Cost
By Date Strategy No.
Checked by Date Source No.
Remarks: _. Page_
6-214
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Notes on Methodology Logic
Step la (Item li, ii) - This step of the evaluation will identify the nature
of the residual generated by the wastewater treatment facility, referred to
as the generator. The residual will be identified as either biological or
chemical, depending on the nature of the treatment at the point source. In
addition, the solids content of the residual should be estimated by con-
sidering the residual treatment process utilized at the treatment facility.
In many instances where more complex treatment processes are required, more
than one type of sludge might be identified.
Step Ib (Item liii) - The feasible disposal techniques are identified in this
step. The table below describes a classification for selecting these tech-
niques that might be useful in identifying the general potential for a
particular residual. However, many local, state, and federal regulations
exist concerning pathogens, solids content, etc; the user is advised to
modify this table to reflect the local condition.
Residual Type
Biological Chemical
Wet Cake Ash Cake Ash
Land Spreading X X -
Landfill X X XX
A wet residual represents a thickened or unthickened residual (solids at 1
to 10 percent). A cake represents a dewatered condition (solids at 15 to
50 percent), and an ash represents the product from an incinerator. The
user should determine the type of residual generated by the treatment
process under consideration. (Although not addressed in thisv methodology,
the user should also consider other residuals handling techniques such as
incineration or composting.)
Step Ic (Item liv) - In this step, the quantity of residual generated by the
source control method is estimated. This information can be developed by
the user for special cases. _The treatment systems curves in Appendix H
indicate an estimate for typical wastewater treatment processes.
Step 2a (Item 2i) - The identification of existing disposal sites is de-
scribed in this step. The sites identified for a specific residual might
6-215
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include any existing residual disposal sites, but more typically would in-
clude the site currently utilized for disposing the existing residual.
-Step 2b (Item 2i) - The identification of potential new disposal sites is de-
scribed in this step, primarily to insure that the user gives some consider-
ation to the site-specific factors associated with development of a new
disposal site. In general, the local authorities will favor utilizing an
acceptable existing site due to the adverse social and environmental impacts
of disposal site development.
Step 2c [Item 2iii) - This step evaluates the remaining disposal capacity at
an existing site. This capacity is most easily identified in terms of the
useful life of the site while operating at the increased disposal rate.
Step 5a - No discussion.
Step 5b (Item 5) - This step is utilized if a new site is being developed or
if the existing site is being expanded because of insufficient capacity. The
site development/expansion schedule should be prepared considering the pro-
ject design flows and anticipated residual generation. The project cost
schedule can then be developed using the cost curves in Appendix H or an
equivalent method. The user should modify any cost curve capital estimate
to reflect total construction cost (e.g., engineering design and construction
contingency) as is done in the TREATMENT FACILITY METHODOLOGY (Table 6-4,
Item 3) using reasonable construction estimates.
Step 4 (Item 4) - This step is utilized only when the disposal site has suf-
ficient capacity to accept the residual. In this case, the residual disposal
cost will consist of the user charge for the particular disposal site of in-
terest.
Step 5 (Item 5) - This step identifies the transportation cost for residual
disposal, which can be developed using the cost curves in Appendix H or their
equivalent.
Step 6 (Item 6) - This step identifies the Present-Worth cost of the residual
disposal alternative under consideration. This step will be utilized to com-
pare the Present-Worth cost of two or more disposal alternatives. When only
one alternative is under consideration, this step will not be used.
6-216
-------
Step 6b (Item 7) - This step summarizes the Present-Worth cost of alternative
residual disposal site evaluations when several sites are under consideration.
Note: this step is not required when only one site is being considered be-
cause the site's cost schedule will be transferred to the appropriate project
cost schedule for the Present-Worth determination.
Step 6c - This step involves the transfer of the cost schedule for the
preferred residual disposal site to the project cost schedule for the con-
trol alternative for which the residual disposal cost is being determined,
e.g., treatment plant construction.
6-217
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6.4.2.13 Transportation Cost Methodology
Discussion
The TRANSPORTATION COST METHODOLOGY is intended to guide the user in develop-
ing a reliable cost estimate for a pipeline conveyance system. This pro-
cedure is applicable for wastewater (including land application and reuse)
and liquid sludge transportation. It is used in conjunction with other
methodologies, such as regionalization and discharge relocation, whenever it
is necessary to determine the cost of transporting wastewaters or sludges by
pipeline.
The initial determination in this methodology is the identification of a
suitable transportation route between the contributing source and the re-
ceiving point. The selected route is then divided into segments defined by
breaks in the slope of the pipeline. Each of these segments is then analyzed
to determine if a gravity-flow condition exists. When it is determined that
gravity flow would not be acceptable for the segment of interest, a force
main is assumed. The cost for each segment thus consists of the pipeline and
the pumping costs required for force main segments. Although not included in
this methodology, the user should also consider other factors which will af-
fect costs, such as local soils and other topographic features (e.g., depth
to bedrock, stream crossings) and right-of-way acquisition. The cost as-
sociated with each segment is then combined to obtain the overall transpor-
tation cost for the relocation of the flow from the contributing source to
the receiving point.
Methodology Logic
A summary of the logic of the TRANSPORTATION COST METHODOLOGY is presented in
Figure 6-31. An expanded flowchart, Figure 6-32, lists the steps to be taken
in determining performance and costs. The worksheets for recording the oper-
ations are presented in Table 6-18. Notes on specific steps or worksheet
items are presented after the worksheets.
6-218
-------
FIGURE 6-31
TRANSPORTATION COST METHODOLOGY
LOGIC SUMMARY
Identify the transportation route
between the sources.
Step 1
Determine the condition of the
transportation route: gravity
or force main.
Step 2
Determine the transportation cost
between the sources.
Step 3
( CONTINUE J
6-219
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FIGURE b-32
TRANSPORTATION COST METHODOLOGY
FLOWCHART
f ENTER }
i
Identify the sources that are being
evaluated and the flow for each projec
phase .
f
Step 1
t
/TABLE 6-18 /
7 Item 1 /
I
Determine the transportation route loc
and profile.
'
Identify segments of the transportatio
by the elevation and station data at s
cant changes in the pipe slope.
i
Determine for each segment the flow co
gravity or force main.
ation Step 2a
/TABLE 6-18 /
7 Item 2 /
t
n route Step 2b
ignifi-
i
ndition: Step 2c
/TABLE 6-18 /
*/ Item 3 /
/TABLE 6-18 /
7 Item 3 /
1
Determine the characteristics of the g
flow segments.
\
Determine for each force main segment
pumping head requirement (see notes) .
\
ravity- Step 2d
/TABLE 6-18 /
•7 ILtilll 4 /
r
the Step 2e
/TABLE 6-18 /
7 Item 5 /
f
Consider a project phase. Step 3a
i
Determine the cost associated with gra
sewers, using the appropriate cost cur
Appendix H or an equivalent source.
i
Determine the cost associated with the
main segments, using the appropriate c
curves in Appendix H or an equivalent
\
vity Step 3b
ves in
t
force- Step 3c
source.
f
V
/TABLE 6-18 /
7 Item 6 J
/TABLE 6-18 /
7 1 LtJlll / /
/TABLE 6-18 /
6-220
-------
FIGURE 6-32 Ccontinued)
TRANSPORTATION COST METHODOLOGY
FLOWCHART
Y
Determine the cost associated with pumping,
using the appropriate cost curves in
Appendix H or an equivalent source.
Determine the transportation cost schedule.
CONTINUE
D
Step 3d
/TABLE 6-18 /
-y Item 9 /
Step 3e
/'TABLE e-is /
~7 Item 10 /
6-221
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TABLE 6-18
TRANSPORTATION COST METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
Item 1 - Project/Phase/Source Identification.
Proj ect:
i.
ii.
Source Identification
Source
Elevation
Design Flow (mgd) @ Phase No.
1
2
3
n
Design Yr
Item 2 I- Transportation Route Profile.
(also locate routd on topographic map)
§
LEGEND
Surface Profile
xxxxxx Rock, Impenetrable
Pipe Route
DISTANCE, (
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-222
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
Item 3|- Critical Segments of the Transportation Route.
Flow Rate: Assumed n-value:
a)
b)
c)
Elevation/Station1
Segment E/S(A) to E/S(B) Slope2 Velocity3 Flow Type4
Notes:
1. Define Elevatipn Station Data from upstream E/SCA) to downstream E/S(B).
2 sioBe - ECB) " ECA)
2. Slope -
Units: ft/ft
3. Determine velocity only for positive slope condition; negative slope
indicates force main (see discussion); use the attached nomograph
(Hydraulic Computations).
4. Flow type: Gravity if positive slope and acceptable velocity (2 fps
minimum); force main for other conditions.
Reference calculation sheets:
Item 4|- Gravity Segments.
Flow Rate: mgd
Segment Flow Rate (mgd) Length (ft)
a)
b)
c)
d)
TOTAL
By
Checked by
Rema rks:
Date
Date
Strategy No.
Source No.
Page
6-223
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
Item 5[- Force Main Segments.
Segment Length Static Head1 Dynamic Head2 Pumping Head5
a) -----
c)
Notes: Static head = elevation difference from upstream to downstream.
2
Dynamic head = See Discussion, Step 2 (Item 5).
3
Pumping head = Static head + Dynamic head.
Reference calculation sheets:
By Date Strategy No.
Checked by Date Source No.
Remarks; Page
6-224
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TABLE 6-18
TRANSPORTATION COST METHODOLOGY
WORKSHEET
COST DETERMINATION
Item 6 [- Project/Phase Identification.
Proj ect:
Phase:
I Item 7|- Gravity Sewer Costs.
i. Reference Cost Curve: Figure H-84 (or' equivalent curve)
Service Life: years
Gravity Sewer Length: feet
Design Flow Rate: »
ii. Cost Determination.
Construction Cost: $
(Compute only for Phases that include sewer construction; adjust
curve cost to reflect installed cost.)
0§M Cost - Start: $
0§M Cost - End: $
Replacement Cost: None
Salvage Value (SV)1!
_ (Service Life - Years to Project End) canital
(Service Life) p
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-225
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
Item 8|- Force Main Cost.
i. Phase:
Cost Curve: Figure H-85 Cor equivalent curve)
Service Life: years
Length: [ ft
a) ft @ mgd
b) ft @ mgd
c) e ft @
ii. Cost Determination.
Segment
Capital Cost1
O&M Cost - Start
0§M Cost - End
Replacement Cost
Salvage Value CSV)'
None
None
None
Compute only for Phases that include force main construction; adjust
curve cost to reflect installed cost.
2_.. (Service Life - Years to Project End) .
SV = (Service Life) x CaPltal
By
Checked by
Rema rks:
Date
Date
Strategy No.
Source No.
Page
6-226
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
| Item 9 -
i.
ii.
Notes :
By
Checked
Remarks:
Pump Station/Pumping Cost.
Phase:
Service Life: years
Pumping Head/Flow:
Flow Rate
Segment Total Head Start End
Cost Determination. (Cost curve Figure H-30, or equivalent)
(a) 00 (c)
Segment :
Capital Cost1
0$M Adjustment for head2 ( ) ( ) ( )
0$M - Start3
0§M - End3
Replacement Cost/Year^
Salvage Valll0 CSV)5
Compute only for Phases that include pumping capacity expansion;
adjust curve cost to reflect installed cost.
2
Compute as described by the cost curve.
0§M Cost = Curve Cost + Adjustment
4Rcnlaccmcnt Co-t - YearS RemaininS in Project-Service Life r__.t_.
Replacement Cost •- Service Life x CaPltal
5C,, (Service Life - Years Remaining in Project) n .«. ,
~V (Service Life) x LaPltal
If Salvage Value is negative, enter as 0 and compute
replacement cost.
Date Strategy No.
by Date Source No»
Page
6-227
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
[item 10| - Transportation Cost Summary.
i. Cost Schedule.
Phase Item Capital Cost Start - O&M End - O&M Salvage Value
1 97
99
TOTAL PHASE 1
2 #7
#8
99
TOTAL PHASE 2
3 97
99
TOTAL PHASE 3
n 97
99
TOTAL PHASE n
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-228
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
Item 10| - Transportation Cost Summary (continued).
Replacement Schedule
Item Year Cost
ii. Present-Worth Cost: $
(Compute only when required.)
By Date Strategy No.
Checked by Date Source No.
Remarks:
6-229
-------
Notes on Methodology Logic
Step 1 (Item 1) - This step identifies the conditions for the transportation
cost evaluation. The flow rate for each source at each phase should be
available from previous evaluations.
Step 2a (Item 2) - This step identifies the pipeline route for the cost evalu-
ation. The user should identify the route on available topographic maps
(e.g., USGS Quadrangle Sheets), with general consideration given to the
natural path between the two locations and environmental constraints. Typi-
cally, this would indicate that the transportation route follows a stream or
other relatively low area. The surface profile between the two sources is
then determined and plotted on the transportation route identification graph.
It is also desirable that the underlying condition along the path be identi-
fied if the information is readily available.. The purpose of this deter-
mination is to locate any underground conditions that would constrain the
type of pipeline that could be installed. For example, a shallow rock de-
posit would limit the depth to which a gravity sewer could be installed, so
this should be identified on the transportation route graph. This infor-
mation is entered onto the graph in terms of the station and elevation of
each critical point (i.e., minimum and maximum elevations for any condition).
The pipeline profile can then be developed on this graph, with Source 1
defined as the receiving point and Sources 2, 3, etc., the contributing
points.
Step 2b (Item 5) - In this step the user characterizes the pipeline route in
terms of critical segments that approximate the anticipated condition. These
critical segments should be as short as required to adequately describe the
pipeline condition, but the user should try to identify a minimum of these to
provide a degree of detail consistent with the other methodologies.
Step 2c (Item 5) - Since a gravity sewer is less expensive than a force main,
this step is concerned primarily with identifying the segments that can uti-
lize a gravity sewer. Each segment is defined by its endpoint elevation and
station, working from the upstream to the downstream end of the pipeline.
The slope for each identified segment should be computed. A positive slope
indicates that the upstream end is higher than the downstream end of the
6-230
-------
segment. The flow velocity can be computed using the nomograph (Figure 6-33),
or by any other accepted method. The flow type for each segment is gravity
flow if the slope is positive and the resultant flow velocity is sufficient
(minimum 2 feet per second). Force main segments are those that cannot be
identified as gravity.
Step 2d (Item 4) - This step identifies the peak flow rate (typically 2.5 to
3.0 times the average flow rate at the design-year condition) and the length
of the critical gravity flow segments.
Step 2e (Item 5) - In this step, each force main segment is characterized as
to the energy (pumping head) required to maintain flow through that segment.
The static head refers to the energy required to lift the water from the
downstream point to the upstream point, and can be considered the elevation
difference between these points. The dynamic head represents the energy
losses (dynamic losses) in the pipeline associated with flow through the
pipe. These dynamic losses are a function of the velocity in the pipe and
the pipe characteristics. As a first approximation, the user can define the
dynamic losses to be equal to 20 percent of the static head since, under
the average conditions, the design engineer would limit total dynamic losses
to a number in this range. For the situation where a more accurate estimate
is required, or when there is a long force main/low lifting head situation,
the user should determine this friction loss using standard engineering
methods.
Step 3a (Item 6) - This step identifies the project and phase to which the
calculations in Items 7 to 10 apply.
Step 5b (Item 7) - In this step, the gravity sewer capital cost is determined
for phases that include pipeline construction. The operation and maintenance
cost associated with the gravity sewer should be determined for every project
phase.
Step 5c (Item 8) - In this step, the force main capital cost is determined for
phases that include pipeline construction. The operation and maintenance cost
associated with the force main should be determined for every project phase.
6-231
-------
"o
.c
- 8 /
-7 J? 12~
- 6 ,/
.s 10-
/
-4 8-
-
-3
6-J
.0002-
.0003 -
.0004 -
.0006 -
.0008-
.0010-
m
q .0020-
o
* .0030 -
5 .0040-
S. .0060^-
OT .0080 =
^.0100 =
s*
/ .0200-
^ .0300-
.0400-
_
.0600-
.0800 =
.1000-
-.0001
- .0002
- .0003
-.0004
—
- .0006
- .0008 ^
-.0010 S*
m ^
- .0020 § /
-.0030'' c
^.0040 o
- .0060 §•
- .0080 OT
- .01 00
- .0200
- .0300
— .0400
- .0600
-.0800
= .1000
n = 0.01 3 or 0.01 5
~
.— 1
-
-2
-
-3
1
-4 ™
a
*-
.0)
c
_ c ~
3 >*
1
0)
-6
-7
-8
-9
-10
— 11
-12
-13
-14
-15
-2
- 1
- 0.9
- 0.8
Adapted from Engineering Manual, Department of Defense,
Corps of Engineers, Part XIII, Chapter 1, June 1955.
FIGURE 6-33 SIZE OF CIRCULAR DRAIN FLOWING FULL
6-232
-------
Step 3d (Item 9) - In this step, the various cost items associated with waste-
water pumping are determined. The project schedule should identify the de-
sired pumping capacity during the various phases of the planning period.
After this step, the user is directed to evaluate the next project phase for
the .cost items.
Step 5e (Item 10) - This step summarizes the costs determined in Items 6, 7,
8, and 9 in a Transportation Cost Schedule. This schedule can be transferred
to the appropriate methodology for inclusion in the project cost schedule or
can be used to develop the Present-Worth cost.
6-233
-------
6.5 Illustrative Example
This illustrative example is presented to demonstrate how the approach pre-
sented in Chapter 6 is employed to develop and evaluate control alternatives
for a 208 planning area. The setting for the example is the hypothetical
Jefferson City area on the South River, which has been used throughout this
manual.
The methodology is employed just as it would be in an actual problem setting.
Water quality objectives are defined, load-reduction strategies are developed,
and the FRAMEWORK METHODOLOGY guides the user in utilizing the component
methodologies to evaluate control alternatives for each wastewater source of
interest.
Notes are recorded directly on the worksheets and on separate sheets entitled
"Illustrative Example Supplemental Notes" to give the user additional infor-
mation about the source of a numerical value, the reason for a particular
operation, or other explanations which clarify the procedure. In order to
reduce the volume of the example, the various methodology worksheets are
filled out completely only the first time they are utilized. If a set of
worksheets is needed more than once, a note is included to indicate how the
user would proceed. An assumption is made about the result if it is needed
for further determinations.
6.5.1 Water Quality Objectives
Dissolved Oxygen criteria and suggested objectives for other water quality
parameters for the South River are presented in Table 6-1. As explained
earlier in this chapter, the water quality standards that are in force for a
particular situation do not always address all important water quality param-
eters. A standard often must be considered a minimum objective for an area.
Separate objectives rcay be set to address parameters other than the most
commonly addressed one, i.e., Dissolved Oxygen. Therefore, a range of ob-
jectives is available for an area, for example, from simply meeting the water
quality standard to controlling pollution from storm water runoff also.
Control alternatives to meet these objectives will probably require a wide
range of costs.
6-234
-------
For the South River area, various objectives for control of individual pa-
rameters and combinations of parameters are proposed for further evaluation.
These objectives are recorded in Table 6-19.
6.5.2 Load-Reduction Strategies
As explained earlier in Chapter 6, a load-reduction strategy is a combination
of percentage load reductions at various sources which will meet a given
water quality objective. There may be a number of load-reduction strategies
which will meet any one objective. A combination of a water quality ob-
jective and a strategy is referred to simply as a load-reduction strategy.
For any area, there may be a number of water quality objectives, several
strategies to achieve each objective, and a wide range of costs to implement
the strategies. This suggests that a decision-maker will have to make de-
cisions on two levels. First, he must decide on the water quality objective
which will be sought; then he must decide on the most cost-effective control
alternative to achieve that objective. The first decision generally will
identify the order of magnitude of dollars to be spent to achieve water
quality (however it might be defined). Control of more parameters with fewer
allowable violations usually requires more money, and selection of a partic-
ular control alternative identifies the approach which supposedly will have
the least total cost to society. Since the decision-maker cannot perform
his function without input, the planner or engineer must develop appropri-
ate cost information for all feasible and potentially desirable strategies.
The Load-Reduction Strategy Matrix, Table 6-19, represents a number of
different water quality objectives for the South River area, and several
strategies for achieving these objectives. The strategies were formulated
by using the water quality impact analysis techniques in Chapter 5. Obvi-
ously, in an area which has a number of sources, there is a very large number
of possible combinations of load reductions which will achieve the desired
objective. The strategies formulated for a planning area should include those
combinations which present a choice, by including significantly different
technological solutions to achieve the desired water quality objectives.
The objectives and strategies presented in Table 6-19 range from control of
one water quality parameter and two sources, to control of five parameters
6-235
-------
TABLE 6-19
LOAD REDUCTION STRATEGY MATRIX
Allocation
Designation
la
Ib
Ic
6 =
7 =
3a,
8 =
9 =
4,
Id
2a
2b
2c
3a
3b
4
5a
5b
2a
2a, 3a
4
2a, 3a,
5b
2a, 3a,
5a, 5b
Objective
DO^-1
DO-1
DO-1
DO-1
DO-1, DO- 2
DO-l,DO-2
DO-l,DO-2
TC^-1
TC-1
TSS1'3-'-!
P^-l
DO-l,DO-2
TC-1
DO-1,00-2
TC-1,TSS-1
DO-l,DO-2,
TC-1,N-1,P-1
DO-l,DO-2,
TC-l.TSS-1,
N-l.P-1
STP I
C% Removal)
55% CBOD
55% NBOD
24% CBOD
24% NBOD
83% CBOD
42% NBOD
16% CBOD
75% NBOD
55% CBOD
55% NBOD
55% CBOD
55% NBOD
75% CBOD
75% CBOD
-
58% N
80% P
55% CBOD
55% NBOD
55% CBOD
55% NBOD
55% CBOD
55% NBOD
58% N
80% P
55% CBOD
55% NBOD
58% N
80% P
STP II
(% Removal)
55% CBOD
55% NBOD
75% CBOD
75% NBOD
83% CBOD
42% NBOD
16% CBOD
75% NBOD
55% CBOD
55% NBOD
55% CBOD
55% NBOD
75% CBOD
75% NBOD
-
58% N
80% P
55% CBOD
55% NBOD
55% NBOD
55% NBOD
55% CBOD
55% NBOD
58% N
80% P
55% CBOD
55% NBOD
58% N
80% P
Separate Storm Combined Sewer
Sewer Runoff Overflow
(% Removal) (% Removal) .
-
-
-
25% UOD
95% TC
99.62% TC
65% TSS
-
95% TC
65% TSS
95% TC
95% TC
65% TSS
95% TC
-
-
39% UOD
25% UOD
24% UOD
99.83% TC
99.62% TC
-
39% UOD
99.83% TC
39% UOD
99.83% TC
39% UOD
99.83% TC
39% UOD
99.83% TC
NOTES:
0 = dissolved oxygen
C = total coliform organisms
SS = total suspended solids
= total nitrogen
= total phosphorus
6-236
-------
and four sources. In an actual situation, a user would probably elect to
start his analysis with the simplest case and proceed to the most complex.
Determinations made for the sources under the simplest case very often will
be relevant in evaluating more complex strategies.
6.5.3 Development and Evaluation of Control Alternatives
When the Load-Reduction Strategy Matrix has been developed, the user is
ready to begin the development and evaluation of control alternatives for
his 208 area. He does this by utilizing the FRAMEWORK METHODOLOGY, and the
component methodologies determined to be appropriate for the area involved.
Worksheets from both the framework and the component methodologies are filled
out and filed as illustrated in the pages that follow.
To further aid the user, a list is presented (in Table 6-20) of the method-
ologies employed in this illustrative example; each component methodology
is used at least once. The illustrative example worksheets are numbered in
the lower right corner just as they would be in actual use. The report page
number appears at the bottom center of the page and is prefixed by a "6-".
Page references within the illustrative example mean the illustrative-example
page numbers in the lower right corner.
6-237
-------
TABLE 6-20
INDEX TO COMPONENT METHODOLOGIES USED
IN ILLUSTRATIVE EXAMPLE
Illustrative
Strategy Source Methodology1 Example Page Number
N/A N/A Framework 1
9 1 Treatment Facility 9
Residuals Disposal 19
Present-Worth 27
Land Application 31
Transportation 38
Present-Worth 50
Wastewater Reuse 55
Treatment Facility 58
Impact Area Modification 67
Regionalization 77
9 3 Land Management 87
1 •' !
Collection System Control 91
Storage/Treatment 100
Component methodologies utilized by other component methodologies are included.
6-238
-------
TABLE 6-3
FRAMEWORK METHODOLOGY
WORKSHEET
\ „ *
6 H
I
4 X
it
X
X
X
H
X
K
X X
t!
W
X
X
'Hie procedures, calculations, assumptions, and judgments presented in the flowcharts
and worksheets are for guidance only, and shcfuld not be interpreted as the only ap-
proach available (or even as the preferred approach'). However, any approaches used
should he consistent with liPA Cost Effectiveness Analysis Guidelines and all other
EPA, State, and local guidelines and regulations.
Identification of water quality objectives, load reduction strategies, and
sources.
a. Define water quality objectives by number and parameters to be
controlled.
Receiving Water Constituents to be Controlled
h'ater\ Total Suspended Total
Quality D.O. (Dry D.O. (Wet Solids Total Total Coliforms
Objective # Weather) Weather) (Wet Weather) Nitrogen Phosphorus (Wet Weather)
l *
Z _X_ X
b. Load reduction strategics represent differing percentage reductions in
load at the various sources of interest for a particular water quality
objective. These strategies are identified by a letter (a, b, c, etc.)
where more than one strategy is proposed for a particular water quality
objective.
c. Identify sources by number:
Source f
Source Type
(Wet or Dry)
Source Description
i)
Sbl
VWC
W*X
WtX
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-239
-------
LESSNO;
E PUMP STATIONS
Q] COMBINED SEWER OVERFLOW REGULATORS
B STORM SEWER OVERFLOW REGULATORS
r*TPl WATER TREATMENT PLANT
IwwTPI WASTE WATER TREATMENT PLANT
—— SANITARY SEWERS
-—— COM9INEO SEWERS
——— STORM SEWERS
• • FORCE MAINS
FIGURE 5-7
JEFFERSON CITY STUDY AREA
COLLECTION SYSTEM
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No»
Page
2
6-240
-------
Illustrative Example Supplemental Notes
The water quality objectives defined in Item li are those indicated by
Table 6-1. These numbers will be referenced throughout this example by
"Number-Letter", where the letter refers to the individual strategy that
meets the water quality objective. An objective/strategy combination will
be referred to as a load-reduction strategy or simply as the strategy.
The impact analysis in Chapter 5 deals with the combined sewer overflows
(identified as Sources 3, 6, 7) and separate storm sewer runoff (Sources 4,
5) as aggregated loads.
For this example, the assumption has been made, for illustrative purposes,
that these aggregated loads can be controlled to the desired level by imple-
menting a control program for Sources 1, 2, 3, and 4.
By
Checked by
Rema rks s
Date
Date
Strategy No.
Source No.
MA
A)/4
Page 3
6-241
-------
Illustrative Example Supplemental Notes
The strategies have been formulated and numbered, and the sources numbered.
At this point, the user begins the iterative evaluation of initial alter-
natives for the various strategies and sources defined above, using:
Figure 6-6 as a guide, Item lii (page 5) for keeping track of strategies
and sources considered, and Item 2 (page 7) to record Present-Worth costs
and information reliability for the various control alternatives considered.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
fiJ/A
A///}
Page
U
6-242
-------
TABLE 6-3 (continued)
FRAMEWORK METHODOLOGY
WORKSHEET
Item 1 (continued)
ii. Record of load reduction strategies and sources considered.
• Check (x) the sources to be considered under each load-
reduction strategy.
• Circle the checks in the matrix after all appropriate control
alternatives have been considered for a source.
• Go to next load reduction strategy when all sources have been
considered for that strategy.
• End when all strategies have been considered.
By
Load Reduction
Strategy
ICL
\*r
1C
\d.
2o*
a£
2c
3ft.
3J2-
M
So.
$b-
4
7
?
9
Source Number
1
X
X
X
X
X
X
X
X
X
X
X
X
(*)
2
X
X
X
X
X
X
X
X
X
X
X
X
3
X
X
X
X
X
X
X
to
4
X
X
X
X
X
X
X
X
(*>
5
6
Date
Checked by
Date
Strategy No. *J/A
Source No.
Remarks;
A///?
Page f
6-243
-------
Illustrative Example Supplemental Notes
For the illustrative example, Strategy 9 will be evaluated. This strategy
has been selected because it requires use of all component methodologies.
Actually Strategy 9 is a combination of a number of less comprehensive
strategies (See Table 6-1). Since the example considers only Strategy 9,
only sources for that strategy are circled in Item lii as a record of evalu-
ation. In an actual case, all x's would be circled since all sources for
all strategies would be considered.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No;
N//J
/J/fl
Page
b
6-244
-------
TABLE 6-3 (continued)
FRAMEWORK METHODOLOGY
WORKSHEET
Item 2J- Feasible Control Alternatives.
i.
iii.
Record the Present-Worth cost of control alternatives determined using
the component methodologies.
Record the worksheet page number (from lower right corner) where the present
worth is recorded in the appropriate component methodology.
Record the relative reliability of the performance and cost information for
the control alternative as identified in Appendixes G and H or at the
discretion of the user.
Load Reduction Information Reliability
Strategy Source Control Alternative Present-Worth $ Page Performance Cost
I ft.
o-nJLf
9
9
9
9
9
9
4
9
9
9
2
1
"3
3
3
*U, 700,000 26
* *iZ> '*V°° &
8
B
0
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No»
/V^/fl
A»//)
Page
6-245
-------
Illustrative Example Supplemental Notes
The treatment facility evaluation included in the next few worksheets con-
siders a single-phase project utilizing the existing treatment facility.
Alternatives (not evaluated) would be abandonment of the existing facility
or a multi-phased project. A complete residuals disposal evaluation is in-
cluded in this treatment facility upgrading, involving consideration of a
new landfill site. Transportation of the treatment plant residual (sludge)
is by truck. The Present-Worth cost of the upgrading project is determined.
By _ Date _ Strategy No. tJ/A
Checked by _ Date _ Source No.
Remarks: _ _ _ _ Page _ 8
6-246
-------
TABLE 6-4
TREATMENT FACILITY METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the.only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
- Program Implementation Schedule.
i. Planning Period: 20 years
ii. Construction phases: I
Flow Design
Phase Timing Projection (mgd) -Flow (mgd)
Year to Year Start End
1* Present to 2.O <) \~J q
2 to
3 to
4 to
n to
'Existing facility not utilized at full capacity.
By
Checked by
Rema rks :
Date
Date
Strategy No.
Source No.
1
I
Page f
6-247
-------
TABLE 6-4 (continued)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Phase
Existing
Facility
1
2
3
n
Effluent Quality
Reference
Cost
Curve**
M-i
UWs-'
(.A**.fl**t
BOD
mg/1
•36
•* > 6
COD
mg/1
*0
^ll)
TSS
mg/1
100
T-P
mg/1
<)
Z*
NH3-N
mg/1
20
mg/1
0
T-N
mg/1
20
9"
T-C
#/100ml
_
iii. Treatment Objectives.
Note: Dissolved oxygen deficits use ultimate oxygen demand inputs
(Table 6-3). These must be reconverted back to CBOD and NBOD (N%)
concentrations to determine discharge limitations (See Appendix H
discussion of Treatment Systems Performance Matrix).
**Treatment System curve number (Appendix H, Figures H-2 to H-15) or
reference number for synthesized system cost curve developed from
unit process curves (Appendix H).
iv.
Existing Facility Characteristics.
Design Capacity:
Service Life:
mgd
3V
years
Years in Service:
Remaining Service:
years
1*1
years
By
Checked by
Remarks:
Date
Date
fa
Strategy No.
Source No.
I
Page to
6-248
-------
Illustrative Example Supplemental Notes
The required treatment level suggests that Treatment System H-12 could be
used. However, for purposes of this example, it is assumed that local con-
ditions require that an alternate system be used. Therefore a treatment
system is synthesized using some of the unit process curves in Appendix H
and some hypothetical "local cost estimates". This synthesized system,
referred to as S-l, will provide the required treatment level. System units
and construction and 0 § M costs are summarized, in the table below:
Synthesized System Jost Estimate
Treatment System Units
App H
Curve No,
Construction Cost
(106 $)
0§M Cost
Service
Life
Wastewater Treatment:
Lift Pumps
Preliminary Treatment
Primary Clarifier
Act. Sludge
Second. Clar.
Nitrification
Denitrification
Two Stage Lime
Filtration
Disinfection
Biological Sludge:
Gravity Thick.
Anaerobic Digester
Vacuum Filt.
Chemical Sludge:
Gravity Thick.
Vacuum Filt.
Misc. Structures
Support Personnel
TOTAL
H-30
H-31
Local Cost Est.
H-34
Local Cost Est.
Local Cost Est.
Local Cost Est.
H-53
H-56
H-58
H-64
H-73
Local Cost Est.
H-64
Local Cost Est.
H-29
H-28
1.10
0.27
2.4
2.30
2.3
3.6
2.5
2
2
10
00
0.28
0.15
0.90
1.15
0.15
1.45
0.35
23.00
32,000
38,000
73,000
160,000
120,000
200,000
600,000
400,000
170,000
87,000
6,000
100,000
200,000
6,000
400,000
8,000
100,000
,700,000
15
30
50
40
30
40
30
40
30
15
50
50
20
50
20
50
By
Checked by
Rema rks s
Date
Date
Strategy No.
Source No.
Page i/_
6-249
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 2 I - Existing Facility Cost.
Note: For the first phase of new facility construction, Items- 2i,
2ii, and 2iii will equal zero since there is no existing
facility.
i. Capital Value (i.e., construction cost plus add-ons).
a. Design Q = • mgd
b. Level of Treatment: Reference Cost Curve H-2
Service Life 3*J'
c. Construction Cost (Curve $)
d. plus Piping - Curve $ x 15% = 310,000
Electrical - Curve $ x 12%
Instrumentation - Curve $ x 8% = ZOf.OQQ
Site Preparation - Curve
Miscellaneous Structures
Site Preparation - Curve $ x 5% v = 1 30,OOO
(.Hcr»*>) = o_
e. Sub-Total 1, Construction Cost (c+d) *
f. plus Sub-Total 1 x Engineering and
Construction 15% =
Sub-Total 1 x Contingencies 15% =
g. Sub-Total 2: Capital Cost (e+f)
h. CAPITAL VALUE OF ENR (Current) fa
EXISTING FACILITY = Sub-Total 2 x 2375* = *' /apJ OOQ
* ENR = 2475, September, 1976.
ii. Replacement Cost.
(compute only if planning period is greater than remaining service
life)
Replacement Planning Period - Remaining Service Life x Capital
Cost = Planning Period Value
at year
iii. Salvage Value.
(compute only if remaining service life is greater than planning
period)
c n .. , Remaining Service - Years to Planning End Y Capita
balvage value = Remaining Service" * Value
at end of planning period.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
4
i
Page 12.
6-250
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 3 I - Expansion Program or New Facility Construction.
Phase Number •
mgd (previous phase or existing fa-
cility; zero if new facility)
i.
11,
iii,
iv.
v.
VI,
vii.
vin,
ix.
x.
xi.
Existing Capacity = 2_
Expanded or New
Facility Capacity
/7
_mgd (design capacity of next phase)
Level of Treatment: Reference Cost Curve H-
Service Life 34
Construction cost of expanded or rfew facili'ty -
enter cost curve at expanded or new facility at
capacity (ii)
,900,000
Construction cost of existing facility -
enter cost curve at existing facility at
capacity (i) <\
Sub-Total 1: Expanded or New Facility <|
Construction Cost (iv-v) =
plus Sub-Total 1 x Piping 15% =
Sub-Total 1 x Electrical 12%
Sub-Total 1 x Instrumentation 8% -
Sub-Total 1 x Site Preparation 5% =
Sub-Total 2: Construction Cost (vi + vii)
plus Sub-Total 2 x Expansion/Upgrading Factor &/» =
Sub-Total 2 x Engineering and
Construction 15% =
Sub-Total 2 x Contingencies 15% =
Sub-Total 3: Capital Cost (viii + ix)
9.10)000
) k>S,Ot>0
' /, 3 yo,ooo
HOOP
CAPITAL COST OF ENR (Current)
EXPANSION OR OF = Sub-Total 3 x 2475*
NEW FACILITY
ENR (Engineering News Record) = 2475, September, 1976.
By
Checked by
Rema rks :
Date
Date
Strategy No.
Source No.
I
Page
?
/
13
6-251
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 4j - Upgrading Program.
Phase Number I
i. Existing Level of Treatment: Reference Cost Curve
(previous phase or existing facility)
ii. Required Level of Treatment: Reference Cost Curve
(for the identified phase) Service Life
iii. Q = [7 mgd (design capacity)
iv. Construction Cost at required level of J
treatment - curve from ii i?3tOOO»flOO
v. Construction Cost at existing level of
treatment - curve from i 4)000/000
vi. Sub-Total 1: Construction Cost of Upgrading
(iv-v)
vii. plus Sub-Total 1 x Piping 15%
Sub-Total 1 x Electrical 12%
Sub-Total i x Instrumentation 8% = J, £2.0,000
Sub-Total 1 x Site Preparation 5%
viii. Sub-Total 2: Construction Cost (vi + vii)
ix. plus Sub-Total 2 x Expansion/Upgrading Factor&% =
Sub-Total 2 x Engineering and '
Construction 15% =
Sub-Total 2 x Contingencies 15%- =
x. Sub-Total 3: .Capital Cost (viii + ix) * 3j>"> ^) 0, oe o
xi. CAPITAL COST ENR (Current)
OF UPGRADING = Sub-Total 3 x 2475*
* ENR = 2475, September, 1976.
/te^vtc* *****
of /u»*k/:t&t^/«"^<*c'«4^ H
**H-»
/to
By _, Date Strategy No. \
Checked by Date Source No. i
Remarks: Page
6-252
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
- 0§M Constant and Variable Cost.
Phase _J _
A/afe*
Level of Treatment: Reference Cost Curve
Timing Design Flow 0§M Cost
Start End
(yr.) (yr.)
\ 30
Start
(mgd)
End
(mgd)
17
Start
End
$
_ Phase _j _ Replacement Costs (Upgraded and/or Expanded Portion)
(Compute if planning period is greater than phase service life)
Replacement Cost Schedule.
Kxpansion
Year Cost
Upgrading
Year Cost
Total
Year Cost
Replacement Cost for Phase | =
Years from Time of Replacement to end of Planning Period
Service Life.
Item 7
••/)•• 0 n •
>it^
'
- Phase _l _ Salvage Value at End of Planning Period.
(Compute if phase service life is greater than years to planning
period end)
(Service Life - Years to Planning End)
Salvage Value = - Service Life - -
Expansion S.V. =
Upgrading S.V. =
Total Phase S.V.
^70,000 $ >> 1*0, OOP
700, OOP
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-253
-------
than "one phase fox
evaluation. If so, the sheets with Items 3, 4, 5, 6, and 7 would be re-
peated at this point in the evaluation, once for each project phase.
By Date Strategy No. ;
Checked by Date Source No.
Remarks: . Pa9e_
6-254
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
) (**%,
Item 8[ - Residual Disposal Cost, using RESIDUALS DISPOSAL METHODOLOGY.
i. Residual Disposal Technique.
Solids Nature
Residual Type
Disposal Method
Transportation
ii. Residual Disposal Cost Schedule.
Phase
Land
Cost'
1»*
>*<£
3
n
Timing
Yr. to Yr.
1
1
1
20
10
10
Capital
I?4,0
Mttooo
6£})0oo
OSM
Start
110,000
M0>coo
End
IHOjOOO
vtotooo
Replacement Cost
Year
ItT
s
l\
Cost
H3,ot>o
1)7,000
Salvage
Value
J£V<90
0
d
i.
^
By
Checked by
Rema rks:
Date
Date
Strategy No.
Source No0
Page
6-255
-------
Illustrative Example Supplemental Notes
Pages 19-26 are worksheets for the RESIDUALS DISPOSAL METHODOLOGY, which is
another component methodology utilized by the TREATMENT FACILITY METHODOLOGY
to make a specific determination, the cost of residuals disposal. The use
of component methodologies in this fashion will occur throughout the example.
See Table 6-20 for an overview of which component methodologies are uti-
lized in evaluating control alternatives for the various sources.
By Date , Strategy No.
Checked by Date Source No. /_
Remarks: ——— Page
6-256
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approacli available (or even as the
preferred approach). However, any approaches used should be con-
sistent with UPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
Item 11- Residual Characteristics.
i. Residual generator method of treatment:
rnd^vLuJufn,
ii. Residual description: Q$-wciyi«g-*50 dt**k} CM^At^uM. -ftv Page T£
6-257
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
- continued
iii. Site capacity evaluation - existing site
a) Useful life at existing disposal rate: ^ years
•* fa*'^A^/q-n^-2^* f°°
b) Existing disposal rate:v "rJl "gET/da^ or ton/day or
cu yd/day
c) Proposed disposal rate: 9 3j 600 /k/fsame units as above)
(use average rate for entire planning period)
d) Useful life at proposed disposal rate = (a) x ^r = 0" I
l400J»/fc>/\ =
/7/W s
By Date Strategy No.
Checked by Date Source No.
Remarks: ___ . Pa9e_
6-258
-------
TABLE 6-17
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
Item 3 |- Cos
t for Development of Residual Disposal Site.
i. Program Schedule.
Phase Timing Design Flows (mgd)
Yr to Yr Start End
1 1 to 2O ^ '7
2 to
3 to
n to
ii. Site Development Schedule.
Design ^ . 2
Phase Flow Land Required • Land Cost
]
(mgd) (acre)
2
3
n
i i/AJ^t-M-KcA*^ ^ n . . . . 'L~~*Z&H
^and Required = '" *"' ' ' acre/mgd U#> '' ^^fT^ ~l"~ '
2
Land Cost
* > ooo / -*** "(nr**^ "
= $ •«•» /acre /^A_^ u_ o* *„* u_c-»\
X f Q ^
iii. Project Cost Schedule - Disposal Site.
Tii
Phase Yr 1
Land
Cost 1
l/$000 30,000 W,OOO Mffnt. 0
ZO 20Z>6OO 70,000 )20,600 ^itrttt O
Capital, computed as described for TREATMENT FACILITY METHODOLOGY; includes con-
struction add on's to reflect installed capital. Capital = curve $ x (1.0 +
Construction Add on's.)
Cost computed as described for TREATMENT FACILITY METHODOLOGY; attach appro-
priate computations.
By
Checked by
Remarks :fl?f,
Date Strategy No. ^
Date Source No, /
!W^.(p
-------
r
cL»*e^
= 17
6r«7.)
303.000
By Date Strategy No.
Checked by Date Source .No.
Remarks'. ~~~~~———- Paqe
6-260
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
Item 4|- Residual Disposal Cost
for Existing Site.
Program Costs
Timing Design Flow (mgd) Residual
Phase Yr
1 1$
2 x*t^
3
n
to Yr Start
M>^/nott
tLjtsi /YufT
_&**»*
a
Determined using
2
Determined using ($
Item 5 - Residu
Appenc
i . Tran
End
J&.1
ten^A
Start
faStfajl
<&^t**
# n / J*tl^ A.AA Av*
Design
Start
*e
*
in AM' SiA
&<> Solids Z0%
<&>«n T>0 %
'•*d$t^fOf>/i n%t3$ )<**«>- S?*»
Flow
End
*
*
srtmlllA
Replacement Cost Salvage
Year Cost Value
If U3,00o 6
/i" II 7,000 *.
*JJl. \fff ***** 74
1 *
Develop capital estimate based on end design flow for each phase;
include construction add on's to reflect installed cost.
2
Develop OgM estimate (start and end) for each phase.
Q± f\ CtT&y 6/vC <AM#Jta, /jfa/njvMXCMAa&r&t &0 £XJL4>On&*x
By
Checked by
Remarks:
"
'If/*
Date
Date
Strategy No. J
Source No. /
Page 23
6-261
-------
*.) 1$ft ^^t^xvW^./*«j>1«4*^G
^'ioM'A^fa/c^^
30%. ^
g- 7
0
>0 O^H c^yt L^/^n
100/0(90 s
By Date Strategy No.
Checked by Date Source No.
Remarks; Page
6-262
-------
TABLE 6-17 (continued)
RESIDUALS DISPOSAL METHODOLOGY
WORKSHEET
Item 6J- Residual Disposal Site Present-Worth Cost
i. Alternative Characteristics:
Residual
Solids
Transportation Method 07v
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
- Project Cost Schedule (Summary of- costs developed in
TREATMENT FACILITY METHODOLOGY) .
Capital Start End Variable Salvage
Phase Year to Year Item No. Cost 05M Q{jM OSH Value
3 (Expand/New) ~ ~~
8 (Residual) »>0>4>000 370,600
Total Phase 1 M0,{tf0,0«> .J,97ty>M 3J-JO,WO
3 (Expand/New)
^(Upgrade)
8 (Residuals)
Total Phase 2
3 (Expand/New)
4 Upgrade)
5/6/7
8 (Residuals)
Total Phase 3
n 3 (Expand/New)
4 (Upgrade)
5/6/7
8 (Residuals)
Total Phase n
-1*
Replacement Schedule
Item 10 - Present-Worth Cost, using PRESENT-WORTH METHODOLOGY
Interest / % (from Water Resources Council
18 CFR 704.39, Discount Rate,
published annually)
Present-Worth Cost $ &'
By Date Strategy No.
iy Date ~SO uYce 7 ffo"«
Rema rks;
-------
TABLE 6-16
PRESENT-WORTH METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgements presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and
Items 1-10 Present -Worth
Planning Period 20 years
Item (Reference Page)
1. Phase 1 Capital
(pg. Z& )
2. Phase 2 Capital
(Pg. )
3. Phase 3 Capital
(Pg. )
4. Phase n Capital
(Pg. )
5. Replacement year (h)
(Pg. 26)
6. Replacement year (i]
(pg. %fc )
7. Replacement year (j)
(Pg. )
8. Replacement year (k]
(pg. )
9. Replacement year (1)
(Pg. )
10. Salvage Value
(Negative Cost)
(pg. rtsJ
By
Checked by
Rema rks : "CJU*t /&**& dmtik
f-jtti*. try
local guidelines and regulations.
Calculation.
Interest -7 %
Amount Present-Worth
W0£o>ooex i.o 10,0 $0tot>o
(Yr 1)
x (sppwfa)
(Yr )
x (sppwf )
(Yr )
x (sppwf0)
(Yr )
1,430,080 x £>.«5,00$x O.Zfr (sppwf2) £.4,3*>><»>»
(Yr 10 )
Date Strategy No. 9
Date Source No. /
gp (pK44m^. kAr**/^r>€^i>- •fX£/>'f'/lf A>T Page 2.7
UHfc"niOftouo*v ^
6-265
-------
TABLE 6-16 (continued)
PRESENT-WORTH METHODOLOGY
WORKSHEET
Item 11 - 19 Present-Worth
Planning Period 20 years
Item (Reference Page)
I A
11. 0§M Phase 1 Constant ';"
(Pg. 2fi>)
12. O&M Phase 1 Variable ^
13. 0§M Phase 2 Constant
(Pg. )
14. OSM Phase 2 Variable
(Pg. )
IS. 0§M Phase 3 Constant
(Pg. )
16. OSM Phase 3 Variable
(Pg. )
17. 0§M Phase n Constant
(Pg. )
18. 05M Phase n Variable
(Pg. )
19.
fefe"*"*^
*T^ ' JL
W)0. s*ipfo*n t /a/
... 0 /P _^JfJ(
XT) fcrt^v6*f&4&~* V'™^
By Date
Checked by Date
Remarks:
Calculation.
Interest 7 %
Amount Present-Worth
70,000 x /0.4 (uspyfdj x 1>Q ZOtSSOtOOO
(#Yrs 2*>tfT7 ^flt+ifitit
^^^n^
faybr&bv"'^*) if r***^1^
Strategy No.
-------
Illustrative Example Supplemental Notes
The next evaluation for Source 1, as indicated by the flowchart Figure 6-6,
is land application of the wastewater. A complete evaluation of an un-
drained application site is included in the attached worksheets. Also in-
cluded is a complete cost determination for the wastewater transportation
pipeline from the existing treatment facility site to the application site.
The Present-Worth calculations are also included.
An underdrained system could also be evaluated using these worksheets. In
this case there would still be a discharge to the receiving water.
The pipeline route evaluated for this example includes force main and gravi-
ty segments and the associated pumping costs. Only one route is evaluated,
but if another route were to be considered, the user could determine the
Present-Worth cost for each.
The Present-Worth analysis included in this example includes all expected
construction expenditures and operation and maintenance items. Salvage
values at the end of the project life and replacement costs for equipment
are included. Finally, a negative cost is identified to reflect assumed
revenues from the land application site for marketable crops.
The land application site evaluated for this example was an undrained site;
thus, there would be no direct discharge of wastewater" from Source 1 to the
receiving stream. Therefore, the original load-reduction strategy, which
was based on a discharge from Source 1 and Source 2, could likely be modi-
fied to allow less treatment at Source 2.
In an actual case similar to this situation, the user would utilize the water
quality impact analysis techniques presented in Chapter 5 to reevaluate the
waste load allocations for use in evaluating control alternatives for the
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
?
/
Page 29
6-267
-------
Illustrative Example Supplemental Notes (continued)
other sources if undrained land application jwere to be the selected alter-
native for the source under consideration. Of course, for control alter-
natives other than undrained land application for Source 1, the original
load allocations for all sources would again be used.
For this example, the original load allocations will be used throughout
since the techniques are the same and, thus, serve for illustration.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
*
/
Page "3o
6-268
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach]. However, any approach used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
PROJECT SCHEDULE
|Item l|- Program Implementation Schedule.
i. Planning Period: 20 years
ii. Existing Facility Conditions.
T>ȣ^LjtFnuttuf
Design Capacity: 9
Years of Service: JtQ
Remaining Service: |M
iii. Treatment Levels.
Note: Dissolved oxygen deficits use ultimate oxygen demand inputs
(Table 6-3). These must be reconverted back to CBOD and NBOD (NH3)
concentrations in order to determine discharge limitations (See
Appendix H discussion of Treatment Systems Performance Ratios).
mgd
years
years
Level
Existing
Facility
Pretreatment
Discharge
Limitations
Reference
Cost
Curve
H-2
H-£*°
VM1/
Parameter Control Levels
BOD
mg/1
.3*
ao
S-l
COD
mg/1
3£b
^
TSS
mg/1
too
*0
^k
T-P
mg/1
4
7
2
NH3-N
mg/1
AO
17
N03-N
mg/1
0
|-TMB. -y ,(. —
iv. Construction Phases: 1 _*<_
T-N
mg/1
JO
r
T-C
#/100ml
__
lU4A4e«x*^ar*#4^
Phase
1
2
3
n
Timing
Year to Year
\ — 10
Design Flow (mgd)
Flow Projection
Start
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKS! lEET
GENERAL SITE EVALUATION
Item 2| - Land Application Ultimate Area Requirement.
i. Maximum Annual Flow Rate at end of Planning Period = I "7 mgd
ii. Application Rate1 = 2-*" in. /week
',,-
in. Non-operating time = I 7 weeks/year
iv. Area Required = 3)800 acres, without buffer zone
(includes area for roads, buildings, etc.)
Gross Area Required (with 200 ft buffer zone)2=
acres
(Use Nomograph "Total Land Requirement", Figure 6-13, or
equivalent)
Items 2ii and 2iii can be used for determining maximum capacity
for potential LA sites in Item 5.
2
Use a more stringent buffer zone limitation if indicated by
applicable Federal, State, or local regulations or site conditions.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
I
Page
*
1
32.
6-270
-------
TAB LI: 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
I Item 3[- Potential LA Sites - Location.
(Attach USGS Quad Sheet or equivalent with potential sites outlined and
identified.)
US6S
/H*Ujj.
By t Date Strategy No.
Checked by Date __^_ Source No.
Remarks: j5~
__
«f et^ ^^^Ji . Pa9e_!2_
6-271
-------
1VOI13H10dAH
rvs'n 'H3Am Hinos)
ssn aisi\n
9-3
»-n
153HOJ-|t t|
3snaHv^
tttttttfttt+ttttrtt
ttttttttttttttttttt
tt'ttttttttttttttttttt
tttttttT + ttttttl't
ttttt + tttttt
t t t t t i t t t t
t t t t t t
en
0) CJ
•M O
(D 1-
1- D
J-" o
t/> tfl
(D 0>
o o
T3 W)
0) JC
JC 1-
U TO
a> E
5-..C
co o
CM
1--
CM
I
vD
-------
I
to
n>
O)
-i
i/i
-o
OJ
IQ
O
IT -
-)
x-
ro
a.
a-
•<
o
QJ
r-l-
CO
O
c
0
ro
z
o
ro
<
0
OJ
r-l-
CO
r-l-
-1
QJ
rf
n>
UD
-<
O
•o
Item 4
Site
1
^
3
- Potential LA Sites Data Sheet. (Sample of factors to be considered. This
is not an inclusive list; see LA references
for additional considerations.)
Approximate
Available
area
(acres)
*
7,000
|Z,C>00
Estimated
treatment
capacity
(mgd)
37
73
Area
of site
presently
irrigated
(percent)
0
O
0
Distance
from
plant
(feet)
(o lOO
'°0t*
Elevation
difference
from plant
(feet)
330
i oo
Homes
onsite
(No.)
H
*
Other
buildings
onsite
(No.)
a
Roads
onsite
(miles)
3.7
14
Comments-
Ma j or
problems or
advantages
0 &C0M «*
/ttv6»*
z)tostk'
famJUAtfai
^ fiUfMtotvi
/•***»• J
tri&rirt&L-'
y cJfauJ* **<*')
6rt*«X'W W
ft<^H*^/lufe
f
LAND APPLICATION METHODOLOGY
WORKSHEET
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
Item 5 •
SPECIFIC
SITE
SITE EVALUATION
\
- Site Implementation Schedule.
i. Planning F
ii. Construct]
Clf diffei
iii. Pretreatme
Clf diffei
iv. Performanc
Curve U-2.
Item 6 •
•eriod: 20 years
.on Phases: '
'ent from Project Schedule, then des
;nt Requirements: Reference Cost Cu
•ent from Project Schedule, then des
:e Characteristics - existing facili
_ CFrom Item liii)
- Pre-application Treatment
i. Use Treatment Facility
Phase
Existing
Facility
1
2
3
n
Item 7 -
Timing
Cost.
Methodology.
0§M Replaceme
Yr. to Yr. Capital Start End Year
N»rk
Jfnr'
WJ&
M
• Land
Ap
CL
Fa
••^*^^*»»MJU*3UJ!»9
Ttawhfirt- ftitiuTy M*n,a>ou>*y, -fi
^^JUAtoA«WW«^*i^tf \Jojfo
in. /week 6tf*»V*^'<
in. /week UWtf'
>
cribe.)
rve W~ **
cribe.)
ty: Reference Cost
nt Cost Salvage
Cost Value
^ytf^Wat^"
^6l£ ^-Vi"tt*^
- 1 _L m *
1tr*rtvk.9
Gwff&nt ca&&A*v^
l
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
lltem 8 - Transp
ortation Cost.
i. Use Table 6-18, TRANSPORTATION COST METHODOLOGY to complete
following schedule:
Ph
ase Capital
1 "}} £(oQ 000
2
3
n
0§M
Start En
120,0*0 W/
Replacement
Year
[item 9 - Applic
/&"
ation Site Costs.
i. Use cost curve in Appendix I
Curve N<
Service
Timing
Phase Yr to Yr
1 |-20
2
3
n
Flow Rate, mgd Design,
Start End
* 17
mgd
17
Replacement
Year
Adjust curve c
2Develop Salvag
which reflects
^Include crop i
By
Checked by
Remarks:
Salvage
J~ Value
W 40*000
Schedule
Cost
1)000,000
if Figure H-16, or equivalent method:
3. H-/&
Life 30uxUra^
Capital
Cost
»?o*5"»
0§M
Start End
*?0/»0 &»
Salvage2 Revenue
Value Start End
£{,70/100 i+opao fyofg
V .
Schedule 39- 20 „ /z**Jt*4
Cost
A/(^vA
ost to reflect installed cost.
e Value = Service Life - Years tc
T>o~
» Planning Enc
Service Life
the remaining Phase value at the planning per
evenues, etc. . -4 tin/
/(Jj& &#&*!*».£&***£'' ***** ~~ *
$>Wl s '&>/*
Date
Date
~v
• x Capital
iod end.
a/et« /^^
le*. /tfY'
Strategy No. $
Source No,, /
Page 37
6-275
-------
TABLE 6-18
TRANSPORTATION COST METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
Item 1 - Project/Phase/Source Identification.
£
Project: r^/Yk
i.
ii.
Source Identification
Source
$«*J{QiOffaji£in
^SS?^!
S«u«*_
Elevation
700 'M-SL.
^/r'MSi.
Design Flow (mgd) @ Phase No.
1
-
2
-
3
-
n
-
Design Yr
-
- Transportation Route Profile.
(also locate rojute on topographic map)
1t>0 -
LEGEND
Surface Profile
xxxxxx Rock, Impenetrable
Pipe Route
DISTANCE,
By
Checked b
Remarks i'
Date
Date
•H
Strategy No.
Source No.
Page
6-276
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
Item 3 - Critical Segments of the Transportation Route.
O <«0
Flow Rate: )"7
Segment
Assumed n-value: 0 . O I i
Elevation/Station1
a)
b)
c)
E/S(A) to E/S(B
«r>
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
Item 5|- Force Main Segments.
Segment Lengtli Static Head1 Dynamic Head- Pumping Ilead^
b) VCX VS/ _J
d)
Notes: Static head = elevation difference from upstream to downstream.
Dynamic head = See Discussion, Step 2 (Item 5).
Puriping head = Static head + Dynamic head.
Reference calculation sheets:
By Date Strategy No. "
Checked by Date Source No, /
Remarks; Page_J/£_
6-278
-------
TABLE 6-18 (continued)
TRANSPORTATION COST NETHODOLOGY
WORKSHEET
COST DETERMINATION
Item 6 1- Project/Phase Identification.
Project:
Phase: /
Item 7|- Gravity Sewer Costs.
i. Reference Cost Curve: Figure 11-84 .(or equivalent curve)
Service Life: iTQ years.
Gravity Sewer Length:
Design Flow Rate: l
ii. Cost Determination.
Construction Cost: $
(Compute only for Phases that include sewer construction; adjust
curve cost to reflect installed cost.)
X
0§M Cost - Start: $ _ S OO
0$M Cost - End: $ _ S"O O
Replacement Cost: None
Salvage Value (SV)X$
1SV - (Service Life - Years to Project End) capital
(Service Life) 1
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
°l
1
Page £//
'6-279
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
Item 8
- Force Main Cost.
Phase:
I
Cost Curve: Figure H-85 (or equivalent curve)
Service Life: p 0 years
Length: £>OOO ft
a) O.^iT/fruAo Jg{% I? mgd
b) ft @ mgd
c) ft @ mgd
ii. Cost Determination.
Capital Cost1
0$M Cost - Start
0§M Cost - End
Replacement Cost
10,000
None
Salvage Value (SV)2 310,OOP
Segment
None
None
Compute only for Phases that include force main construction; adjust
curve cost to reflect installed cost.
2 (Service Life - Years to Project End)
SV " (Service Life) X CaPltal
By
Checked by_
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-280
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
1 Item 9 -
i.
CO
M
<0
ii.
Notes:
*£\
By
Checked
Rema rks :
Pump Station/Pumping Cost.
Phase : '
Service Life: 1^ years
Pumping Head/Flow: Q .
&**f*1f-^0 Flow Rate
Segment Total Head Start End
| - -^ 83' 1"*^ rt"^4
4-6 ?fc' 1 "»j/ «7/»-^i
7-9 */*' ?>~Jx '?"-**(
Cost Determination. (Cost curve Figure H-30, or equivalent)
(a) (b) (c)
Secment:
Capital Cost1 1,000,000 1, 000,600 l,O«,o«o
O&M Adjustment for head2 ( ) ( ) ( )
OSM - Start3 U^,0«d t'iyOOQ "i3>OdO
0§M - End3 7^»«>«>«> 70,000 #1,0 00
Replacement Cost/Year4 ^O.DOO/^ 310,t>oo/,f 33^000/^
s»i»flE. value (SV)S "^ A/**»*- A/*n*'
(,8«^vt^^4*- < y^*i°°* * ^3O,«0«
©mln-rmrut fn-t - Years R
-------
"TbT/ji.
CL
12,000
**'
1
43
111,000
= 17
17
M /
17
4 3^
C
MM^
V
17
ntOOi> H,000 W0
"33000 7^000 70,000 53
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No«
Page jjT«T
6-282
-------
Illustrative Example Supplemental Notes
For certain projects, additional phases might be identified to consider the
staging of pump .stations, etc. The appropriate sheets (Items 6, 7, 8, and
9) would be included at this point.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
*
/
Page 4«T
6-283
-------
TABLE 6-18 (continued)
TRANSPORTATION COST METHODOLOGY
WORKSHEET
|ltem 10| - Transportation Cost Summary.
i. Cost Schedule.
Phase Item Capital Cost Start - O&M
1 #7 fgtifOOO 5*OO
#8 t] |0,tf>00 S'OO
#9 ^,000,000 hV<>«
End - O&M Salvage Value
-Too 9 2, ooo
6-284
-------
TABLE 6-18 ( continue $
TRANSPORTATION COST METHODOLOGY
WORKSHEET
[ite-n 10| - Transportation Cost Summary (continued).
Replacement Schedule
Item Year Cost
/, 000,000
ii. Present-Worth Cost: $ , ^_ _ „
37*ft£*
(Compute only when required.)
^a^vrf AfpQ&
\,
By ' Date Strategy No.
Che:ked by Date Source No.
Rerrirks: Page
6-285
-------
TABLE 6-5 CCONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
[item 10
i.
Phase
1
2
3
By
Check
Remar
- Monetary Cost Evaluation
Cost Schedule. ( (M <*>£ „• P * ]° '
Timing Capital Start End Variable Salvage
Yr to Yr Item Cost 05M O&M 0§M Value
I.Zlo 0.J2 0.20 - OAO
17.00 M9 0.9? — g. kl
#9 •"•• "•
-i|.-22 I.OJT l-W 0.03ff* $.5-3
TOTAL PHASE 1 ^ /> + iff J+*«*-J J~' ~J
TOTAL PHASE ?. - -
TOTAL PHASE 3 ^
t, si / aO «\ 0. l1^ "" /i r><-iJ
Vffrfrt^^' ^** ^L Q
Date Strategy No.
ed by Date Source No.
ks: fleZZmli L/J*^t> flP^lC/9T5fl/0 n6H>obot-Qiy Pag
Revenues'"
Start End
0 0
k.
0 O
A0b 0.^
0.0k 0.14
9
/
e— ^^
6-286
-------
TABLE 6-5 (CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
- Monetary Cost Evaluation (Continued).
Timing Capital Start End Variable Salvage Revenues
Phase Yr to Yr Item Cost OP,M 6§M 0§M Value Start End
#6
#7
#8
#9
TOTAL PHASE 4
Replacement Schedule
Item Year Cost ( ? X
By . Date Strategy No. 7
Checked by Date Source No» /
Remarks: Page
6-287
-------
TABLE 6-16
PRESENT-WORTH METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgements presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and
Items 1-10 Present-Worth
Planning Period 20 years
Item (Reference Page)
1. Phase 1 Capital
(pg. MS")
2. Phase 2 Capital
(pg. )
3. Phase 3 Capital
(Pg. )
4. Phase n Capital
(Pg. )
5. Replacement year (h)
(Pg. )
6. Replacement year (i)
(Pg. )
7. Replacement year (j]
(Pg- )
8. Replacement year (k)
(pg. )
9. Replacement year (1]
(Pg. )
10. Salvage Value
(Negative Cost)
By
Checked by
Remarks:
local guidelines and regulations.
Calculation.
Interest 7 %
Amount Present-Worth
"31.220)000 „ •*( 27.0 0(
(Yr 1)
x (sppwfa)
(Yr )
x (sppwf )
(Yr )
x (sppwf0)
9Q
(Yr )
1,000,000 x 0 3t (sppwfhj -$4,0,000
(Yr l:T)
x (sppwf1)
(Yr ) ,
x (sppwf J )
(Yr )
x (sppwf )
(Yr )
x (sppwf1)
(Yr )
-9,J30.0fl0Y 0 26 fsnnwf Z1 — 2^60)00
ft S* U • &• V ^O^J^J Vi J. J f
(Yr 2.0 )
Date Strategy No. ^
Date Source No. 1
Page. £fO
O
6-288
-------
TABLE 6-16 (continued)
PRESENT-WORTH METHODOLOGY
WORKSHEET
Item 11 - 19 Present-Worth Calculation.
Planning Period 20 years
Item (Reference Page) Amount
11. 05M Phase 1 Constant *)0&0)006
(PS- D
12. 0§M Phase 1 Variable 39,000
(PS- )
13. 0§M Phase 2 Constant
(PS- _J
14. 0§M Phase 2 Variable
(pg- )
tl»*£**4tA i
f£*vw** | M nnfi(\
15. •ew- Phase ft Constant -u^uu'/
IPg. )
Wv«»>t*«.* 1 ,i „„ .
16. 9$M Phase fi Variable -4,000
(Pg. )
17. 05M Phase n Constant
(Pg. )
18. OSM Phase n Variable
(Pg. )
19.
JL
fjpfatifae*- C*>*
By Date
Checked by Date
Remarks:
Interest ~? %
'x MM (uspwfd) x 1.0
x 77.i"(gspwfd) x 1.0
(#Yrs 20 ;Yr 1)
x (uspwf6 x sppwfa)
TFTFs ;Yr )
x (gspwf6 x sppwfa)
(#Yrs ;Yr )
Oo.()fJ-4> f b
x (uspwf x sppwf )
(SYrs 10 ;Yr | )
x " (gspwf x sppwf )
(#Yrs 20 jYr 1 )
x (uspwf8 x sppwfc)
(#Yrs ;Yr )
fj A
x (gspwf6 x sppwf )
(#Yrs ;Yr )
TOTAL PRESENT-WORTH
Strategy No.
Source No.
Present -Worth
II-, \oo>ooo
2,9^*0,000
-(,40,000
- 7/0)000
$ W 7, J20, 000
?\
6-289
-------
Illustrative Example Supplemental Notes
In many situations, the user would wish to evaluate another potential land
application site. This would be done by repeating the calculations for
Items 5, 6, 7, 8, 9, and 10 and inserting them at this location. After
evaluating all alternatives, the user would continue to Item 11.
By '
Checked by
Rema rks :
Date
Date
Strategy No.
Sogrce No.
*
1
Page ^*
6-290
-------
TABLF- 6-5 [CONTINUED)
LAND APPLICATION METHODOLOGY
WORKSHEET
PRESENT-WORTH COST EVALUATION
[item ll[- Present-Worth Cost.
_ Site Present-Worth Gost Reference Sheet
\ J\t>\10>000 5-0 t
By Date Strategy No.
Checked by Date Source No.
Remarks: JZZZZZHI__ Page
6-291
-------
Illustrative Example Supplemental Notes
The reuse of the treated wastewater from Source 1 is evaluated in the follow-
ing worksheets. This example is not complete in that Present-Worth costs
are not computed. However, the cost schedules specific to this evaluation
are developed with appropriate commentary.
The potential reusers identified in this example currently use irrigation
water from groundwater wells. For this example, additional treatment of
the treated wastewater is assumed necessary for the reuser's use to demon-
strate the development of the additional treatment cost. Also developed is
a cost schedule for the reuser's alternative wafer cost for the replaceable
portion of their water supply (i.e., the portion that could be replaced by
treated wastewater).
These wastewater reuse cost evaluations develop two Present-Worth costs.
The first is the estimated cost incurred for transportation and treatment
of the wastewater for reuse. The second is the alternative cost of the
reuser utilizing the projected water supply. Comparison of these two costs
indicates which represents the least monetary cost, and thus indicates if
an economic incentive might exist for reuse (i.e., reuse cost less than
projected supply cost).
If reuse appears economically attractive, the user can develop total project
costs for reuse by using the appropriate component methodologies. The
Present-Worth cost of the total project would be carried to the FRAMEWORK
METHODOLOGY WORKSHEET, page 8, to compare with other control alternatives.
By
Checked by
Rema rks :
Date
Date
Strategy No.
Source No.
Page
f
/
<1
6-292
-------
TABLE 6-12
WASTEWATER REUSE METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not
be interpreted as the only approach available (or even as the pre-
ferred approach). However, any approach used should be consistent
with EPA Cost Effectiveness Analysis Guidelines and all other EPA,
State, and local guidelines and regulations.
It<
•
Bv
Cl
R<
;m 1 - General Reuse Criteria.
i. Total municipal water demand approaching X5^
existing water supply? YES l^V
ii. Existing water supplies, unavailable or
insufficient for new uses (e.g., irrigation, ^^.
industry)? YES MM)
iii. Existing water supply subject to environ-
mental degradation (e.g., salt-water __
intrusion, aquifer drawdown)? YES QjO)
iv. Point source wastewater effluent available
in sufficient quantity to satisfy potential /••^•x
new needs? (YES) NO
v. Point source disposal technique involves ,-,
unusually high costs? WE^ NO
vi0 Planning area includes any large uses x-^x.
of non-potable water? (YES) NO
vii. Absence of restrictions (riparian rights) /~*>k
or related water law? yYES) NO
viii. Expressed interest on the part of x"^"N
potential wastewater reusers? (YES/ NO
\
\/^t ** ** f**04rr*&>»A'' TQ fH. /wvMJt. AM t»u (J*'v*/»wv*i'/
&** ^v^x/rueii-;
t Date Strategy No. 9
iccked by Date Source No. /
jmarks: Pa9e 5*4
6-293
-------
0\
rO
fs,
33
n
rj
0)
1
-o
0)
to
n
5-
^
n
n
tt>
Q.
cr
o
QJ
(5
(XI
Q
c
-1
n
ro
o
CD
•<
O
OJ
(B
C/»
-1
01
r-r
(D
id
~*
O
[ It oir. J [ - Potcnti.il Peus^ Source Identification
Potential , I'ri—.ivii Pro ioc toil
rtater l.euser i*atili' SourLiv -,iter i..iteil l.itrr l.hi.unifv "iu.ilitv
Ident i t'icaticn Tre.itnont ll-o Cost Cost Current I'e-ign^ Dei i rod Minimum Rel i.ihi li ty Hist.mcc
I.V.VMPl.r,:
1. Ceor^ia Power nintllnei/ CoolinK SO.l.Vlniui ',i'.-.\ l..|rard l.lr.nd "(>°l' S.|°f-pll complete .1milc«,
Plant, r'.itchell. screened, hater i;al (".d ngd (I^ISS) pi', ~.J 7.0-7.S across
Mr. John Phi 11 ir- -iettled. fi rn Flint
Plant engineer niniraim] KiM'r
J. Dlue Valley Private i*ellf Irrij;a- <;. ON/HUH' S'1.-- 4(1(^,1101) No toxic same lou ^ mi lo<
Pecan l;am. no treatnenf tion j;al i'.pd*~ metals,
Mr Tom ^oun" puppini' ("l.n-- lou t!is-
Otncr i-ost Nnv! sulvinc
norn.tl
' j>!l
Ml.anV County Private v>ol 1, Irric.i- S.IJ/1'"'() 50. '.s iiiii.nnii "in>,i>ro sane loh 8milc>
Clu*' no tre.itnent tion j'.al >;pd ':|sd
punpin:'. l'\n - t P'-Sl1)
cost \'ovl
0 (i J i? 'UP SU MZhjd
A) J(A, '. k«* wW* fst*™^"-* faw* At£< fiw~ff&
f\ O fi
(/ A /) /7 if^™^^* * t^jb *— @*
^i ™* JU^^^^- ^r^f^- •
^
3*
HI_J
^j
m f-
f~ cr"
H m
m
< ?3 G°*
O 1
?3 ?3 I-1
7^, trj ro
co c;
FT; IT; o
m o
H r^; n)
m rt
as-
o c
O C!)
O P-
5\^_^
en .
i""-i
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
POTENTIAL REUSER EVALUATION
Reuser:
Item 3 - Point Source Treatment to Meet Reuse Criteria .
Reuser Water *
Quality Requirements
Existing Wastewater
Effluent Quality
Existing Wastewater
Effluent Quality
Control Criteria
Upgrade
Technique
Reference Cost
Curve
N/A
M-3
M-n.
H-tf)
Reuser/Point Source Critical Parameters
Q
V*
0.7
°).0
1.0
0.7
BOP
rj*
n
loo
r
/IW
TSS
"V*
^t,
*0
s
/^A
^j
-
A/m.
MT-
fr^L
-
H-^?
Identify the cost curve for upgrading each identified parameter to the reuser
criterion; identify the required system under "Reference Cost Curve" from
individual curves.
Item 4 - Treatment Requirement Cost Schedule to Meet Reuser Criteria.
(Use TREATMENT FACILITY METHODOLOGY to define costs for treatment above that
required for discharge)
Phase
Timing
Yr. to Yr.
Capital
Start End
Replacement Cost
Year
Cost
Salvage
Value
Existing
Facility
ZQ
3?) ooo
(3,000
jfaT+f* <•-!*.
0s
**4lfA
*£**
"%frn.
By Date Strategy No. J
Checked by Date Source No.
Remarks: gelfrye*vtt ef^ta£"?*&/ cUA&nlt. t/n& Jff iJj&m V- Page_
6-295
-------
TABLE 6-4
TREATMENT FACILITY METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all
other EPA, State, and local guidelines and regulations.
I Item 1 - Program Implementation Schedule.
i. Planning Period: 20 years
ii. Construction phases: 1
Flow Design
Phase Timing Projection (mgdj Flow (mgd)
Year to Year Start End
- 1* Present to
-2" / I to
3 to
4 to
n to
*Existing facility not utilized at full capacity.
By
Date Strategy No.
Checked by Date ] Source No.
Remarks: ~"~~ Page-
6-296
-------
TABLE 6-4 (continued)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Phase
Existing
Facility
1
2
3
n
Effluent Quality
Reference
Cost
Curve**
Hotb
H-*1
BOD
mg/1
9fk
COD
mg/1
M.
TSS
mg/1
-JL
T-P
mg/1
tffZt*
NH3-N
mg/1
«j'£^£
N03-N
mg/1
•i.i J "•
5£u«*
T-N
mg/1
*&x
T-C
#/100ml
(JA+d^f.
*>o
.
Treatment Objectives.
Note: Dissolved oxygen deficits use ultimate oxygen demand inputs
(Table 6-3). These must be reconverted back to CBOD and NBOD (NH3)
concentrations to determine discharge limitations (See Appendix H
discussion of Treatment Systems Performance Matrix).
**Treatment System curve number (Appendix H, Figures H-2 to H-15) or
reference number for synthesized system cost curve developed from
unit process curves (Appendix H) .
iv. Existing Facility Characteristics.
Design Capacity:
Service Life:
mgd
years
Years in Service:
Remaining Service:
years
years
By
Checked by_
Remarks:
Date
Date
Strategy No.
Source No.
Page £
6-297
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 3 - Expansion Program ornfew Facility Construction^"*^
Phase Number '
i. Existing Capacity = AJffrJl, mgd (previous phase or
existing fa-
cility; zero if new facility)
ii. Expanded or New ^
Facility Capacity =* 1 •* mgd (design capacity of next phase)
iii. Level of Treatment: Reference Cost Curve n-iT^
Service Life /J*u*K
iv. Construction cost of expanded or new facility -
enter cost curve at expanded or new facility at
capacity (ii)
v. Construction cost of existing facility -
enter cost curve at existing facility at
capacity (i)
vi. Sub-Total 1: Expanded or New Facility
Construction Cost (iv-v)
vii. plus Sub-Total 1 x Piping 15%
Sub-Total 1 x Electrical 12%
Sub-Total 1 x Instrumentation 8%
Sub-Total 1 x Site Preparation 5%
viii. Sub-Total 2: Construction Cost (vi + vii)
ix. plus Sub-Total 2 x Expansion/Upgrading factors/ft
Sub-Total 2 x Engineering and
Construction 15%
Sub-Total 2 x Contingencies 15%
x. Sub-Total 3: Capital Cost (viii + ix)
xi. CAPITAL COST OF ENR (Current) awf)
EXPANSION OR OF = Sub-Total 3 x 2475* jj^?>
NEW FACILITY
* Em = 2475, September, 1976.
^ -f.^-*
/VWT1 /V^wwrofl .
* 20,000
=*ao,oo«
= ->>ooo
= n.too
1, ItOO
1, OOO
***tooo
—
= «J>Z06
MjZOO
*-S6,«oo
= *-i7,000
By Date Strategy No. ^
Checked by Date Source No.
/
Remarks'. Page £0
6-298
-------
TABLE 6-4 (CONTINUED)
TREATMENT FACILITY METHODOLOGY
WORKSHEET
Item 5 - 0§M Constant and Variable Cost.
Phase _J
Level of Treatment: Reference Cost Curve
Timing Design Flow 0§M Cost
Start End Start End Start End
(yr.) (yr.) (mgd) (mgd)
1 20 6. "7 I'iT $^000 $ ^tOOO
Item 6 - Phase _ Replacement Costs (Upgraded and/or Expanded Portion)
(Compute if planning period is greater than phase service life)
Replacement Cost Schedule.
Upgrading Total
Year Cost Year Cost Year Cost
If '"2,000
Replacement Cost for Phase 1 =
Years from Time of Replacement to end of Planning Period . n
Service Life X CaPltal
- Phase | Salvage Value at End of Planning Period.
(Compute if phase service life is greater than years to planning
period end)
Salvage Value = (Service "f-fearsto Planning End)
Service Life
S.V. =
Upgrading S.V. =
Total Phase S.V.
By • Date Strategy No. :
Checked by Date Source No.
Remarks; .Page
6-299
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
I Item 5 I - Reuse Transportation Cost Schedule.
Phase
Existing
Facility
1*
2
3
n
Timing
Yr. to Yr.
1
+Cv
10
*£ «/i
Capital
NX a*
3,200,000
<. 4444AWV4
0§M "
Start
_ •
T>&CA/
2.0,000
^L far
End
^C
30,000
* - +
Replacement Cost
Year
if
r9&*> )„«
V
Cost
$0)000
^\*M^O^^J *
I
Salvage
Value
1)200,000
Item 6 - Wastewater Reuse Project Costs.
i. Project Cost Schedule.
Timing
Phase Yr to Yr
1
Capital Start End Variable Salvage
Item Cost OSM 0§M OgM Value
#4 37,000 £,000 4,000 - 0
352,100,000 *0, COO 30,000 - 1,200,000
TOTAL PHASE
: ! 2,2^0)000 Ut600 3^,000 700 ')200,000
#4
#5
TOTAL PHASE 2
#4
#5
TOTAL PHASE 3
By
Checked by
Date
Date
Remarks: flfl
Strategy No.
Source No0
Page
6-300
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
Item 6 |- Wastewater Reuse Project Costs (continued).
Timing Capital
Phase Yr to Yr Item Cost
Start
05M
End
05M
Variable
05M
Salvage
Value
n
#4
#5
TOTAL PHASE n
Replacement Schedule
Year Cost
$0)000
ii. Present-Worth Cost (using PRESENT WORTH METHODOLOGY)
Interest ' %
Present-Worth Cost $
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No,
Page
6-301
-------
TABLE 6-12 (continued)
WASTE WATER REUSE l^ETHODOLOGY
WORKSHEET
Item 7 j - Reuser Replaceable Water Costs.
(Cost that would be incurred for replaceable water supply without
wastewater recycle)
i.
Cost Schedule.
Phase
1
//
3
n
Timing
Yr to Yr
\ *o
ftjU^vi&JLQtM
1 701
AJtU^CC
Recycle Water
Use*, gpd
Start
a 00,000
300,000
End
$06,1)00
7ob,ooo
Unit Water
Cost2
$/1000 gal
S5S< &4
o.ot CM
0.14 0.-3J
Annual Water
Cost3, $/year
Start
6,8-00
?>«ltfO
End
37,000
£7>e»o
11.
Recycle Water Use represents the portion of total reuser water
2requirement that could be satisfied by treated wastewater.
Unit Water Cost represents projected cost for existing supply if
adequate, or the unit cost for development and treatment of a new
-supply.
Annual Water Cost = (gpd) ($/gal) (365 days/yr)
Reuser Replaceable Water Present-Worth Cost.
(using PRESENT-WORTH l^ETHODOLOGY) : $
Item 8
- Wastewater Reuser Relative Costs.
i. Replaceable Water Cost: $
(Alternative Present-Worth cost for reuser water needs that can be
satisfied during the planning period by treated wastewater;
from Item 7 ii)
ii. Reused Wastewater Cost: $
(Present-Worth cost to utilize treated wastewater; from Item 6 ii)
iii. Other Factors: (describe factors other than cost that will affect
further evaluation)
'/lfe«*a**»^
•-tL
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No,
Page
6-302
-------
TABLE 6-12 (continued)
WASTEWATER REUSE METHODOLOGY
WORKSHEET
Item 9 - Potential
Reuser/Point-Source Combinations
Point Source Reuser Identified Present-Worth Costs
ID Q,mgd ID
J)
f\Jcr>\Si. ^0fas>r
AJc£L: iRi
four
0«U»a
By
Checked by
Remarks:
Wastewater Replaceable Non-Monetary
Q,mgd Reuse " Water Total Cost Incentive
__ t j, ^0tfa *
L /u>4ev /VH^Wl fncnryrnJULi ur*J**wJi J&/xJUuM*0>)
TtA***. C^r^U^Ufj O^^^t ^OWl^j G<*^h/»4dl£tiLt~)
Date Strategy No. 3
Date ' Source No. /
Page. f?
-------
Illustrative Example Supplemental Notes
The following worksheets outline the evaluation of Impact Area Modifications
as a control alternative for Source 1. This portion of the example is not
worked to completion because the required cost computations have been pre-
viously demonstrated in the treatment facility and land application control
alternatives evaluations. However, the determinations specific to this
methodology have been utilized.
The general receiving water condition in this example has been defined using
the water quality impact analysis techniques in Chapter 5 of this manual,
which consider all contributing sources and their relative impact. This
information identifies the potential usefulness of the modifications pre-
sented in this example.
If the discharge relocation example had been carried further, the Chapter 5
impact analysis would be utilized to determine the level of treatment at
the proposed discharge site. If a reduced treatment level were indicated,
then a cost reduction for treatment might be realized, depending on the
magnitude of the transportation cost that would also be incurred.
Artificial reaeration is not a viable control alternative for this example
because the critical water quality parameters are nitrogen and phosphorus,
which would not be substantially affected by reaeration. The information
and steps that would be considered for a potential situation are indicated
on the worksheets.
Flow augmentation also is not a viable control alternative for this example
because the critical water quality condition is defined by the long-term
concentration of nitrogen and phosphorus, but this modification is appropri-
ate primarily to relieve a short-term stiuation. The worksheets have been
marked to indicate the appropriate entries to be made when this evaluation
is appropriate.
By Date Strategy No. T_
Checked by Date Source No. /
Remarks5 ' Page
6-304
-------
TABLE 6-14
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not be
interpreted as the only approach available (or even as the preferred
approach). However, any approach used should be consistent with EPA
Cost Effectiveness Analysis Guidelines"and all other EPA, State, and
local guidelines and regulations.
Item l[- Receiving Water Quality.
Source 1J I
Water Quality Conditions:
/VJ/WAfcA to
/^V^J^C^^^ &******+*£*->
By Date • Strategy No. 7
Checked by Date Source No. /
Remarks: ~~~ Pa9e
6-305
-------
TABLE 6-14
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Discharge Relocation Evaluation.
Item 2
«J
- General Criteria for Discharge Relocation.
1. Is this source a principal cause of the ^^
critical stream condition? C^Ey NO
2. Are there several significant sources . ^-x.
near this source? (YES) NO
3. Would relocation be relatively ^
inexpensive? fis NO
4. Is there a major (or larger) stream
nearby that could receive the source? YES (NC
Item 3| - Alternate Discharge Site Identification.
(Factors: Less stringent water quality criteria; lower net
source loading; increased dilution due to tributary
flow)
Site Location Distance
tefeafcr OB**. '°*
b) _ _
c)
>°^ff**;C^
By Date Strategy No.
Checked by Date Source No,
Remarks; Page
6-306
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Site
Evaluation
| Item 4|- Modified Source Level of Treatment (from Impact Analysis, Chapter 5),
Level
Existing
Discharge
Site
Alternate
Discharge
Site A
Alternate
Discharge
Site B
teferenc
Cost
Curve
Item 5|- Discharge Relocation Transportation Cost Schedule .
(use the TRANSPORTATION COST ^ETHODOLOGY)
By
Checked by_
Remarks:
Date
Date
Strategy No,
Source No.
Page
6-307
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Item 6 -
Phase
Existing
Facility
1
2
3
n
Item 7 |
i.
Phase
Existing
Facility
1
2
3
n
Modified Treatment Level Cost Schedule .
(use TREATMENT FACILITY METHODOLOGY)
Timing
Yr. to Yr.
Capital
Y**4 On,
Otfiffa*.
0§M
Start
r/*A<
End -
Ux*
f
Replacement Cost
Year
C^^tfTa-
*trt^*™^( *
Cost
iJ
Salvage
Value
- Project Cost.
Project Cost Schedule .
Timing
Yr. to Yr.
Capital
1/IU»Jve
tJfc^U,
Ut^t^L
i
0§M
Start
£}l> a
j|c*yt.
i±. Project Present-Worth Cost: $
End
n*v»wj"i
V*~
i
Replacement Cost
Year
t
UL myfy /
i
Cost
f)
Salvage
Value
(use PRESENT-WORTH NETHODOLOGY)
By
Checkec
Remarks
Date Strategy No. ^
hy Date Source No. 1
. Page 70
6-308
-------
TABLE 6-14
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
ARTIFICIAL REAERATION EVALUATION
Item 8
Item 9
A.
B.
Item 1C
i.
By
Checl
Rema
- Receiving- Body Dissolved Oxygen Requirements.
Condition Dissolved Oxygen, mg/1 @ Location
o) / /
Water Quality Limit ^&A*}/L /^.u*ev/vru£4 Artfc^^.dU
Ae^ulXcrv* /9*v«» D.o. e^*^/tn<^*u£ut(//C(nu/
A**^ £>rva>p»M}Ti«4 A***- AW^ 6^vfec
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Item
10
ii.
Phase
1
2
3
n
Item
- Artificial Reaeration Requirement (continued).
Reaeration Project Phasing.
Timing
Yr to Yr
11
Phase
Existing
Facility
1
2
3
n
Item
12
i.
Phase
Existing
Facility
1
2
3
n
Reaeration
Oxygen Demand, Ib/hr
Start End Capital
t&* e.rtf/xLeU./^u&fl
/M4t«m / wL -/>(&&(. fa/ /snftr
I v '' I •
th£, "DegflTrtgvr P0ciury
05M
Start End
Jk
A*^
0§M
Start
a
\r 01*44
^WVO>V5
Replacement Cost
Year
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
FLOW AUGMENTATION EVALUATION
1 1 tern 13
Do
(Y
Coi
- General Applicability of Flow Augmentation as a feasible control
alternative.
critical water quality conditions o"ccur at low flow? . v
es or no) Y*4 Critical Parameters, if yes; 0.0. C /0u° 'f?v' ^ ** •-)
mnents: (Special conditions, model assumptions, reference sheets)
Item 14
i.
ii.
Item 15
i.
ii.
iii.
a)
b)
By
'Checke
Remark
- Flow-Augmentation Capability.
<£f9Wi to/VUfS. _
Existing Reservoir low-flow augmentation capacity: &*Mptkt &ffi> cfs
Duration: days
Proposed Reservoir low-flow augmentation capacity i /&OLMntyvi, cfs
Duration: days flU/fer-m/wlt/Ctfw
- Modified Source Load Control with Flow Augmentation.
Available Flow for Augmentation for the required
duration Cyjttwi H) cfs
Revised stream low flow of o -
Revised Level of Treatment < \ f) ' 0 d
$fitf*n (hntp+^Qsrdhp*! (WviutotL'S) ^vfunrinnfd Sv&Xi &>*»
Critical Parameter Revised Control Level ^p"**«*
g^fjftlt . filnJb
ynjWUSWT
/uftue? do^'ttf
/1*vv**Gi*j
/flfr*SS*>) ("yC.V)
Date Strategy No. 9
^ u,v Date Source No. /
5. Page 13
6-311
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
Item 16|
i.
Phase
Existing
Facility
1
2
3
n
- Flow Augmentation Cost
Modified Level of Treatment Cost Schedule.
Timing
Yr. to Yr.
Capital
1^
/M/X/vUr t*
J?J
/ivn^feaJuu
0§M
Start
End
/JVC&JLtJU. /CO
i r«?e
ffT*e«r
Replacement Cost
Year
favJkntx
V
Cost
Jt
iry
Salvage
Value
ii. Flow Augmentation Cost Schedule.
Phase
Existing
Facility
1
2
3
n
Timing
Yr. to Yr.
Capital
"rfUcWx
it Teen
C&fcns*
#^A*Jlr
f
Jlfafcvi ,
0§M
Start
J*t*
nt*tr
G*ewuflit
•wtJ&y)
End
^6^7,
6K»<-ir
>.j^d
*>&i
Replacement- Cost
Year
&M*<&
/yM/l*M
t/^*^ X**j /¥¥
feasvid
^w^v^T^^^Tw*
Cost
i^ J*4*at
jk, ^
«sr*4 CA4
-------
TABLE 6-14 (CONTINUED)
IMPACT AREA MODIFICATION METHODOLOGY
WORKSHEET
[Item 16[ - Flow Augmentation Cost (continued).
iii. Project Cost Schedule.
Phase Year to Year
Capital Start
Item Cost O&M
End Variable Salvage
O&M O&M Value
Total Phase 1
Total Phase 2
Total Phase 3
161
161
1611
161
1611
Total Phase n
Replacement Schedule
Year Cost
iv. Project Present-Worth cost.
Interest
Present-Worth Cost $
By
Checked by
Remarksi
Date
Date
Strategy No.
Source No.
Page 7V
6-313
-------
Illustrative Example Supplemental Notes
The evaluation process of Strategy 9 would normally continue at this point
with an evaluation of the control alternatives for the next source, as in-
dicated by the flow diagram (Figure 6-6). The evaluation of Source 2
control alternatives is identical to that shown for Source 1; therefore,
these calculations have not been included in this example.
Following the evaluation of all sources for each strategy, the evaluation
of regionalized control facilities is investigated. The following work-
sheets demonstrate one approach for regionalization.
Typical information concerning potential site identification and evaluation
has been included in the appropriate worksheet items. However, other
factors may be more significant for the planner's area of interest.
This example demonstrates regionalization of residuals disposal as well as
treatment facilities. Again, only the information concerning site identi-
fication has been indicated since all cost determinations are similar to
those presented in previous methodologies.
By
Checked by
Rema rks :
Date
Date
Strategy No.
Source No.
1 **
Page
f
4 •*•
7t
6-314
-------
TABLE 6-15
REGIONALIZATION METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not be
interpreted as the only approach available (or even as the preferred
approach). However, any approach used should be consistent with EPA
Cost Effectiveness Analysis Guidelines and all other EPA, State, and
local guidelines and regulations.
Wastewater Treatment Regional Site Evaluation
Item II- Source Identification.
(Attach topographic map with sources located)
Level of Control/
Source/Location Flow Critical Parameters
) I /SP*M
b) T. / SD*2 II -» 30
d)
e)
f)
g)
h)
i)
j)
10
1)
m)
n)
By
Date Strategy No.
Checked by ~~~~~~ Date Source No.
Remarks: ,
6-315
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
Item 2 - Regional Site Identification.
(.Attach topographic map with
Available
Area
Site/Location (acres)
a) ST>*1 STp 30
b) st>*zsr? *r
sources located)
Estimated
Max. Flow
- (mgd) Existing Condition
io ^^J f^^t^u VTP
0 U j
?O ^ffM^L ts8vir>nAt»«i ST)9
c) 5, (C^V^^/TH^J I/O ^00 r&t*>»?/Ub'y>4f &***
fa*™&i<*** «*^|
el
fl
El
hi
il
tt^fadffpj,
-
J)
kj
1)
ml
n)
By Date
Checked by Date
Remarks:
Strategy No. 9
Source No. / *>ut Z
Page •?£•
6-316
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
Item 3 - Potential Regional Site/Source Combinations.
Combination
I.D. No.
Source 1
I.D.
SO*/
Q (mgd)
17
n
1-7
Source 2
I.D.
3o
3o
3o
I.D.
src
Regional Site
Max
Site Q (mgd)
fco
to
uoo
Max
Design Q (mgd)
4-7
47
By •
Checked by_
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-317
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
REGIONAL SITE EVALUATION
Regional Combination No.
|Item 4|- Level of Treatment at Regionalization Site.
Parameter Raw Wastewater Discharge Level
.'•> _. «v
a)
b)
Level of Treatment
.
Level of Treats: W- 11
Item 5| - Regional Site Wastewater Treatment Cost Schedule, tf
(Use the TREATHEKT FACILITY METHODOLOGY) '
Phase
Timing
Yr. to Yr.
Capital
0§M
Start End
Replacement Cost
Year
Cost
Salvage
Value
Existing
Facility
fcfiWM*.-
Item 6| - Wastewater Transportation Cost Schedule.
- (Use the TRANSPORTATION COST fETHODOLOGY)
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page s-0
6-318
-------
TABLE 6-15 (continued)
REGIONAL!ZATION METHODOLOGY
WORKSHEET
Ite
ml- Regionalization Cost Evaluation.
i. Cost Schedule (Regional Combination No. )
Timing Capital • Start End Variable
Phase Yr to Yr Item Cost O&M O&M O&M
Salvage
Value
— * 0 . (1 t (\ ftJJ 0 f?tfi.l\~.L
#5
It 6
TOTAL PHASE 1
// 5-
// 6
TOTAL PHASE 2
// 5
// 6
TOTAL PHASE 3
#5
// 6
TOTAL PHASE
Replacement Schedule
Item Year Cost
ii. Present-Worth Project Cost: $_
By
Date Strategy No.
Source No. / ***«.
Checked by Date -p-
Remarks: _ —
6-319
-------
TABLE 6-IS (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
| Item 8 |- Present-Worth Cost.
Separate
Regional Source I.D. Treatment Costs Regional
Site I.D. Ho. 1 No. 2 Source 1 Source 2 Treatment Cost
Ctn^'fc'fcKfc /Wbwn*J2*2£Jl C^A^Lc*ti<)
Wfr/vwrdbrtA C*T)4 /i>yvC£n/6t/C tAu&. ^J^JL/^yJ^
"^LuaTttMu /Jk»J$AsnJhteJlL <** ^tfP** cfa^twUS^y
. /)/) -A • n . /? . Or 7 . /
&ddk&nvdterrj^^
By Date Strategy No.
Checked by Date Source No. >
Remarks: Page_£z._
6-320
-------
TABLE 0-15 (continued)
REGIONAL!ZATION METHODOLOGY
WORKSHEET
Residuals Disposal Regional Site Evaluation
I Item 91 - Residuals Generator Source Identification.
Residual Disposal Residual Characteristics
Source/Location Flow (mgd) Method Quality
a) S.P.* > 12
b) S.E
c)
d)
e)
f)
g)
h)
i)
j)
k)
1)
m)
n)
By Date Strategy No.
Checked by Date Source No.
Remarks: Pa9e_
6-321
-------
TABLE 6-15 (continued)
REGIONALIZATION METHODOLOGY
WORKSHEET
[item 10| - Potential Residual Disposal Sites.
a)
d)
e)
f)
g)
h)
i)
j)
k)
1)'
m)
n)
Site/Location
Available
Area
(acres)
3.00
Estimated
Capacity
Existing Condition
3D. «t 2.
By
Checked by_
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-322
-------
TABLE 6-15 (CONTINUED)
REGIONALIZATION METHODOLOGY
WORKSHEET
Item 11 - Potential Regional Site/Generator Combinations.
Regional Site
Generator
Site I.D.
Capacity
a.
I.D. Location
60 S.D.*i
Quantity
/7/*«y(
S -f
H-17.
b.
Item 12[- Regional Site/Generator Combined Present Worth Costs.
("Using the RESIDUALS DISPOSAL MI-THODOLOGY)
(Using
Combination Present Worth Cost
Generator I.D. at Combination Present Worth Cost Separate
a.
b.
TOTAL
TOTAL
•**
By
Checked by
Remarks:
Date
Date
Strategy No. _ 1
Source No» / »yut IT
__ Pa9e
6-323
-------
Illustrative Example Supplemental Notes
The monetary cost evaluation for achievement of Strategy 9 load reductions
for Sources 1 and 2 is complete at this point. All costs for this evalu-
ation have been entered in Table 6-3, Item 2, as they were generated.
The illustrative example continues at this point with an evaluation of wet
weather, Sources 3 and 4.
The first of the control alternatives to be considered for wet weather
sources is the LAND MANAGEMENT METHODOLOGY. For Source 3, the feasibility
of controlling the TSS and TC loadings through land management is considered.
By Date Strategy No. ?
Checked by Date Source No. 3
Remarks: Page 86
6-324
-------
TABLE 6-6
LAND MANAGEMENT METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgements presented
in the flowcharts and worksheets are for guidance only, and should
not be interpreted as the only approach available (or even as the
preferred approach). However, any approaches used should be con-
sistent with EPA Cost Effectiveness Analysis Guidelines and all other
EPA, State, and local guidelines and regulations.
Item 1 [ Land uses and land use activities of concern.
Land Uses and
Land Use Activities
Wasteload Applicable Land
P TSS' TC2 Management Alternatives
Percent
t Reduction*'*
BODc N P TSS TC
i) Load reduction requirements:
ii) Land management alternative performance capability.
Land Uses and Applicable Land Performance Range-Percent Reduction
Land Use Activities Management Alternative 'BODg N P TSS TC
A^afrjufeg^lt fc-g. ?M> 80S>f/e**^
^ S&tnwJVtJh fa Vu.
*3lM&JL*&f
See Table 6-7.
Most probable number/100 ml
By
Checked by_
Remarks:
Date
Date
Strategy No.
Source No,
Page 97
6-325
-------
TABLE 6-6 (continued)
LAND MANAGEMENT METHODOLOGY
WORKSHEET
Identification of alternatives which will achieve required reduction.
Land Uses and
Land Management Param-
Land Use Activities Alternatives eter
TSS
Waste^
.JLoad.
Lperform- IfWaste- 1
[ance CapajLload Red.J
~Cwi *m0*&w
-------
TABLE 6-6 (continued)
LAND MANAGEMENT METHODOLOGY
WORKSHEET
[ Item 4|Capital and 0§M Cost (From Appendix G).
Land
Management Affected Land
Alternative Use/Activity (Acres) Capital Cost 06M Cost
Item 5 I Present worth cost of land management alternatives.
Land Management Information Reliability^
Alternatives Present Worth Cost Performance Cost
From Appendix G
By Date Strategy No. 9
Checked by Date Source No. 3
Remarks; Page $q
6-327
-------
Illustrative Example Supplemental Notes
The degree of pollutant reduction achievable through land management control
alternatives may or may not be what is required by the load reduction
strategy. Therefore, collection system controls, the next wet-weather con-
trol alternative in the framework (Figure 6-6), may be evaluated as an ad-
ditional control alternative or as an alternate approach. In this example,
collection system controls will be evaluated as a separate control alter-
native.
By Date Strategy No.
Checked by Date Source No.
Remarks: Page
6-328
-------
TABLE 6-8
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not be
interpreted as the only approach available (or even as the preferred
approach). However, any approaches used should be consistent with
EPA Cost Effectiveness Analysis Guidelines and all other EPA, State
and local guidelines and regulations.
[item 1[ Sewer System Characteristics.
Type of Overflow
Outfall No. Subarea Location1 Sewer Segment Type2 Control Device3
1
2
3
4
5
Locations should be referenced to a map using outfall and subarea numbers.
Combined sewer, storm sewer or unsewered.
Swirl separator or conventional regulator.
By Date Strategy No. ff
Checked by Date Source No0 3
Remarks: Page ff/
6-329
-------
TABLE 6-3 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Item 2 I Pollutants (UODs, TSS, TC, P, N) to be controlled (from Load Reduction
Strategy Matrix, Table 6-19).
Segment No.
Pollutant Parameter
Required % Reduction
r
OOP
TC
Item 5 [• In-line storage volume.
Segment No.
Hydraulic
Capacity
Dry Weather
Flow
Internal
Storage Capacity
f0l£ •' Xtfrc'gvfc MAtVArtU&d tfrfettC (v fy*W>v*4%As ^^/^^/^rml^^Mt*-
'kkoi&t^/wntfcwij, toJj*s^»^*JCwt**£^^
M3M*t*/6**JJk*s'*<> fsjym^i, 3-1^ gy>x»MU 3 "74 tff t^Uy/^K^t^^jP. *PK
/7««3w^), fcrrThiQ Ajt^frQufSJlrto *W«T»IJ
-«-•-•--•- *- * • — -- ^"<2W7A*'x«tv
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Cost of utilizing available in-line storage from cost information
information in Appendix-G, or an equivalent method.
Type of Construction 0§M Total Present
Segment No. Control1 Costs Cost Worth Costs2
Item 5 [ Sewer segments with deposition problems.
Segment No.
3
Extent of Problem
Source of Problem^
Weir, gate, etc.
"Using PRESENT-WORTH METHODOLOGY
Obstructions, slack velocity, etc.
By
Checked by_
Remarks:
Date
Date
Strategy No.
Source No.
Page 93
6-331
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Item 6 I Impact of sewer flushing on pollutant concentrations in overflows.
Outfall No.
Segment No.
•3
Pollutant
Parameter
T35
TC
Concentration
BeforeAfter
'jtJLM&Jaf
Cost of sewer flushing using cost information, in Appendix G, or an
equivalent method.
Segment No. O&M
Total Present-Worth Costs
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Page
6-332
-------
TABLE 6-3 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Item 8 Cost of measuring conveyance capability using cost curves in
Appendix G or an equivalent method.
i. Polymer injection costs.
Total Present-Worth
Segment No. Construction Costs 0§M Costs Costs1
*****
ii. Increased Pumping capacity at the wastewater treatment plant where
influent interceptor is surcharged.
Existing Increased Construction -0§M Total Present-Worth
Capacity Capacity Cost Costs Costs •*•
XUsing PRLSiiNT-WORTH METHODOLOGY
By Date Strategy No.
Checked by Date Source No0
Remarks'. Page
6-333
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Cost of other collection system controls as appropriate, using
Appendix G or an equivalent method.
Type of Constructidh 0§M Total Present-
Segment No. Control Costs Costs Worth Costs1
1Using PRLSUNT-WORT11 METHODOLOGY
By
Checked by
Remarks :
Date
Date
Strategy No.
Source No,
4
•3
Page %
6-334
-------
TABLE 6-8 (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Item 10 [ Collective effect on runoff volumes and loads of all collection
system controls found to be feasible.
Segment No.
Control
Alternative
Load
% Runoff Pollutant Reduction
Controlled Parameter Achieved
./TMd
*fc /C* MtmffttdJL
/VClUU&tfVi /fW»7WX>/t6wMU»>t^
V» /) . ST
to /YC&UAJL "fefco
(~>\i ,
V * it '
tofrw/*
* * * j - S)
TSS
VO^pHe^/iwU^C^?/t<»«^^X^pr&v<^ 6<^t^«^U<< L^^JjJLt^t
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
Paged?
6-335
-------
TABLE 6-8 • (continued)
COLLECTION SYSTEM CONTROL METHODOLOGY
WORKSHEET
Item 11 Summary of feasible collection system control alternatives.
Collection System Control Present-Worth Costs
Total
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
9
3
Page qg
6-336
-------
Illustrative Example Supplemental Notes
The investigation of storage/treatment options in this example takes into
account the internal storage achieved in the .collection system. A storage/
treatment option is selected for evaluation which involves storage and
treatment of the storm overflow at the overflow site. Other options are
covered in the discussion.
By Date Strategy No.
Checked by Date Source No,
Remarks: Page
6-337
-------
TABLE 6-9
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
The procedures, calculations, assumptions, and judgments presented in
the flowcharts and worksheets are for guidance only, and should not
be interpreted as the only approach available (or even as the pre-
ferred approach).. However, any approaches used should be consistent
with EPA Cost Effectiveness Analysis Guidelines and all other EPA,
State, and local guidelines and regulations.
Item l| Sewer System Characteristics.
Outfall No. Subarea Location1 Sewer Segment Type2 Type of Control Device3
\
~
^Locations should be referenced to a map using Outfall and Subarea numbers.
^Combined sewer, storm sewer, or unsewered.
Swirl separator or conventional regulator.
By _________ Date Strategy No.
Checked by ~ Date Source No.
Remarks: ~~~~~~~_
6-338
-------
TABLE 6-9 (continued)
STORAGE-/TREATMENT METHODOLOGY
WORKSHEET
Item 2 Pollutant Parameters (BODg, TSS, TC, P, N).
Segment No. Pollutant Parameter Required % Reduction
crss
3 I TC
TS
TC
Item 3 ] Results of collection system controls.
i. Quantity of design storm runoff volume stored in internal storage of
collection system Q.$ mg. £ Jfarn, (Jv«wjA
ii. Remaining runoff volumes and load:
Volume: fe mg.
Flow: &*5
Load: mg/1 BOD5
mg/l TSS
mg/1 N
t/ioo ml J2v»WC<( , A -.
,
^
By Date Strategy No. "j
Checked by Date Source No. 3
Remarks: Page }Q\
6-339
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
i. Cost of Regulator, from information in Appendix G, or equivalent
method.
Construction Cost $
0§M Cost $
Total Present-Worth Cost $
(using PRESENT-WORTH METHODOLOGY) ^
/)*«*£. A*vt*^ /o^p^oriJov ^w,
ii. Cost of swirl separator, using Table 6-11, or equivalent method.
Design flow ft /"KfrU (
Construction Cost $
0§M Cost. $
Total Present-Worth Cost $ *4 1
(using PRESENT- WORTH METHODOLOGY)
| item 5 Cost of storage tanks, from Table 6-11, or equivalent method.
Type of storage: Settling Complete mix
Construction Cost $
O&M Cost $
Total Present-Worth Cost $
fusing PRESENT-WORTH METHODOLOGY) .
' — ' ^t;x£efl>rCVt/WX.
By Date Strategy No.
Checked by Date Source No. 3
Remarks: ~"
6-340
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 6[
i. Design Storm Characteristics.
Intensity in/hour
Duration - .__ hour
Frequency /year
AJ<#L:
ux£*n fAdj*j&#n
ii. Inlet hydrograph(s) for design storm (storm runoff entering the
sewer
Method
Sub-ar
TIMg^
0
\.o
\ if
3-0
3-0
X'.?
t'o
2a I
fa^ro
0^
^^
bQ
MO
9
o
Sub-are
TIME
;a
FLOW
Sub-ar<
TIHE
;a
FLOW
NOTE: Plot hydrographs for each subarea on separate sheets of graph paper.
By
Checked by
Remarksi
Date
Date
Strategy No.
Source No.
9
Page
6-341
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
iii. Inflow hydrograph to overflow control structure,
Routing Procedure
TIME
i.«r
3.0^
M>
o
0.4'
FLOW
fro
MO
21
13
iv.. Overflow hydrograph .from the control structure.
(Attach rating curve for specific structure)
TIME
FLOW
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
*
3
Page / Ql4
6-342
-------
Illustrative Example Supplemental Notes
The user may use any applicable routing procedure to develop the inflow
hydrograph to the overflow control structure. The routing procedure should
take into account the use of in-line storage.
For this illustrative example, the volume retained by in-line storage
(0.8 mg) is deleted from the hydrograph (shown by the shaded area on
Plot A), and the actual inflow hydrograph begins at a time equal to 1.5
hours. The ordinates shown were taken from the inlet hydrograph plot.
The user can determine the overflow hydrograph using the inflow hydrograph
and a rating curve for the particular overflow control device. For this
illustrative example the overflow hydrograph is assumed to be the same as
the inflow hydrograph to the control structure.
By Date Strategy No.
Checked by Date Source No. j
Remarks: Page
6-343
-------
70 r
PLOT A
INLET HYDROGRAPH SUBAREA 1
INFLOW/OVERFLOW HYDROGRAPH SUBAREA 1
Inlet Time
Inflow/Overflow Time
0
1 2
Time (hours)
Inflow/Overflow TIME 012
By
Checked by /
Remarks:
Date
Date
Strategy No.
Source No«
Page \Q(*
6-344
-------
TABLE 6-9 (continued)
STORAGE/TREATMHNT METHODOLOGY
WORKSHEET
Item 6 | - Continued
v. Mass Curve from Overflow hydrograph.
TIME
O
O.I
O.I
o'.
-------
II
o
O
PLOT B
MASS CURVE
25
50
3.1 mg
75 - 47 mgd
31 mgd
[0M = TM = 62.5 mgd
16 'mgd
123
TIME (hours)
By
Checked by_
Rema rks 2
Date
Date
Strategy No.
Source No,
Page
6-346
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
| Item 6 | - Continued
vii. Cost of storage, using cost functions from Table 6-11, or equivalent
method, PRESENT-WORTH METHODOLOGY.
Type of storage j
Stored CuHiiti'ia.Lluu G'ust 05M.Cost Present Worth Cost
00 0
|
. \
000
NOTE: Plot Volume to be stored and Present Worth Cost.
Volume
By Date Strategy No. 3
Checked by Date _ _ Source No. 3
Remarks: . Page |
6-347
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT- METIIODOLOGY
WORKSHEET
Item 6 - Continued
viii. Cost of on-site treatment, using cost functions from Table 6-11, or
equivalent method, and PRESENT-WORTH METHODOLOGY.
Treatment Unit
Treatment Unit
Treatment Unit
Treatment Rate Construction Cost 0§M Cost Present Worth Cost
a.
137,000
I, frl
QOo
1)
, (900
,000
Treatment Rate Construction Cost O&M Cost Present-Worth Cost
r,oop
34.000 I)
Treatment Rate Construction Cost 0§M Cost Present-Worth Cost
NOTE: Plot a cost curve for each type of treatment unit on the same set
of axes.
Treatment Rate
By
Checked by
Remarkst
Date
Date
Strategy No. 9_^
Source No- ?.
Page_MjO
6-348
-------
•H
12
8
r
PLOT C
TOTAL PRESENT WORTH COSTS vs STORAGE VOLUME
3 4
STORAGE VOLUME (mg)
TOTAL PRESENT WORTH COSTS vs TREATMENT RATE
1
DISSOLVED
AIR FLOTATION
MICROSCREENS
10 20 30 40 50 60
TOTAL PRESENT WORTH COSTS (mil $)
70
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No«
Page
q
$
Ul
6-349
-------
, TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 6 - Continued
ix. Cost of treatment at the existing plant.
a) Cost of discharging effluent to the interceptor and treating at
existing plant.
i. If interceptor is adjacent to overflow control device (as
in combined sewer) , no cost is associated with discharge
to the interceptor.
ii. If interceptor is not adjacent to the overflow control device,
the cost to construct a sewer to transport the effluent can
be determined using the TRANSPORTATION COST METHODOLOGY.
PRESENT WORTH METHODOLOGY;
Flow to be Transported _ Sewer Construction _ Present Worth
and Treated _ Construction Cost 0§M Cost Cost
By Date Strategy No. ' ?
Checked by Date ^_^^^^^^^^ Source No. ?
Remarks: Page J ) -
6-350
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
- C-tln-d
b) Costs of upgrading/expanding existing treatment facility using
TREATMENT FACILITY METHODOLOGY and PRESENT-WORTH METHODOLOGY.
Treatment Construction
Rate Cost Of,M Cost Present-Worth Cost
c) Total Present Worth cost of treatment at existing facility.
Total .Present-Worth Cost of
Treatment Rate Transportation and Treatment
By Date Strategy No.
Checked by Date Source No,
Remarkst Page
6-351
-------
TABLE 6-9 (continued)
STORAGE/TREATMF.NT METHODOLOGY
WORKSHEET
x. Least-cost combination of storage and treatment.
Treatment Least-cost Present-Worth Storage Present-Worth , Total Present-
Unit Cost of Treatment Volume Cost of Storage Worth Cost
3« yn*j*n***n »> 334,000 »>g 4-7 "3,
](, tn^xnvKt^ t^^^oo 3.1
NOTE: Plot total Present-Worth cost of storage and treatment versus
treatment rate.
Least-cost combination of storage and treatment.
$
fffth*.
By Date Strategy No. 7
Checked by Date Source No. 3
Remarks.' _IIIIIIIIIIIIIII Page \{tf.
6-352
-------
1
h—I
s
t—l
ea
H O
w •
iH
D. *»•
s
1
OJ
CO
PLOT D
TREATMENT RATE vs TOTAL PRESENT-WORTH COST
I
10
20 30 40
TREATMENT RATE (mgd)
SO
60
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
T
Page )
6-353
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 7
i. Cost of laying pipe to connect new regulator to existing outfall pipe
(if significant), or cost of laying a new or larger outfall pipe, from
cost curve in Appendix H, Figure H-84.
Construction Cost $
05M Cost $
Total Present Worth Cost $
(using PRESENT WORTH METHODOLOGY)
ii. Cost of Disinfection (where required) from curve in Appendix H,
Figure H-26.
Construction Cost $ (»0)OOQ
06M Cost $ <> tQO
Total Present Worth Cost $ "?#) 0°°
(using PRESENT WORTH METHODOLOGY)
_- J .
•--So
too
By Date Strategy No. 7
Checked by Date Source No. *3
Remarks: Page__/_/£_
6-354
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
[ Item 8 | Cost of sludge handling.
i. On-site sludge handling.
a. Sludge treatment (using cost curves in Appendix II).
1) Organic sludges
Lime stabilization (Figure 11-79)
Construction Cost $
O&M Cost $
Vacuum Filtration (Figure H-68J
Construction Cost $
O&M Cost $ _____
2) Inorganic sludges
Vacuum Filtration (Figure H-69)
Construction Cost $
0§M Cost $
3) Subtotal $
b. Sludge transport (using cost curves in Appendix H, Figures H- 86
through H-90).
Method:
Construction Cost $
05M Cost ' $
c. Sludge disposal (using cost curves in Appendix H, Figures H-81
through H-83).
Method: '_
Construction Cost $ ' ~
OSM Cost $
d,, Total cost for on-site sludge handling.
Construction Cost $
OF,M Cost $
e. Total Present Worth Cost $
(using PRESENT WORTH METHODOLOGY)
ii0 Sludge handling at existing wastewater treatment facility,
a. Sludge transport to existing facility
By Date Strategy No. 9
Checked by Date Source No, 3
Remarks; Page 117
6-355
-------
TABLE 6-9'(continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 8
b.
c.
d.
e.
Wa*5/« cA-A'A
ft/y< jfcwvtrMfKj
fjY^Tftifitnv- t3
By
Checked by
Rema rks t
Continued
1) If sewer is storm sewer, determine cost to construct sewer to
connect with sanitary sewer interceptor to treatment plant,
using TRANSPORTATION COST METHODOLOGY.
Construction Cost $
Of,M Cost $
2) If sewer is combined, existing interceptor capacity should be
sufficient to transport sludges to the existing wastewater
treatment plant.
Sludge treatment.
Determine if there is capacity available in existing sludge handling
facilities to accept additional sludge volumes from the treatment
of storm overflows. If not, determine cost to provide additional,
sludge handling capacity at the existing facility, using TREATMENT
FACILITY METHODOLOGY.
Construction Cost $
0$M Cost $ '
Sludge disposal (using cost curves in Appendix H, Figures H-8 1,
82, or 83).
Method:
Construction Cost $
0§M Cost $
Total cost for sludge handling at existing wastewater treatment
facilities.
Construction Cost $
05M Cost $
Total Present Worth Cost $
(using PRESENT WORTH METHODOLOGY) , . . . ., . J^
; fcM~~*A/f*vt**i Ya^(P^'t^^'1^^^'^^6tT*f^/^
.//ALVWI JU ~'A ['it /it /s-f -gin. */44£«M /pltMJf*. &*><( vfaitf /no O^LtUM^n^J tstr&t
l^tir*,v+fi«nG^1>~4tf^
T2T^n._ m . At *j «M A £i { A^.f^rJ? /hf^fPft-ivVTltv rt m+$ SfrLfjTsVmfiffA**} * TAM ^«M f^Xii^t 0 (A*&
•X^WfffAfaefc'™
+**ni /h/Juvt) yt^/vfijlM^VtrvZfl .
Date Strategy No. 9
Date Source No, "3
Page Jiff-
6-356
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 9 [ Total Present Worth Cost.
Sewer Segment
|
Sewer Type (s
to
tO-H
0 -P
P
e
•p e
•H 4->
C/) Oi
1 0
^J
e
p oi
rf rH
Cu
P
C 60
m r*
e -H
p P
Oi U1
2«
E- UJ
p;
fn O
0 -H
P -P
p, Q
m "3
0 f-l
f-l p
0) 10
s §
1-H U
c
o
•H
4J
O
0)
(4-1
p;
-H
•H
Q
-H
60 ><:
•o w
•-< P
CO oi
/Vtf ,
Ctfit
' Total Present -
Worth Cost
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No,,
Page
6-357
-------
TABLE 6-9 (continued)
STORAGE/TREATMENT METHODOLOGY
WORKSHEET
Item 10[ Regional!zation of storage/treatment components, using
REGIONALIZATION METHODOLOGY.
Components regionalized:
Regional Facility:
Construction Cost $
0§M Cost $
Present Worth Cost $ -
(using PRESENT WORTH METHODOLOGY)
By Date , Strategy No. y
Checked by Date Source No. 3
Remarks; Page 12,0
6-358
-------
Illustrative Example Supplemental Notes
The evaluation of control alternatives for wet weather sources also includes
consideration of reuse. This utilizes the same component methodology as for
dry weather sources; therefore, the worksheets are not included in this ex-
ample. The differences in the evaluation procedure will typically include
consideration of storage requirements and reuser reliability requirements.
Bv
Checked by
Remarks: .
Date
Date
Strategy No.
Source NO.
9
3
Page |2-/
6-359
-------
Illustrative Example Supplemental Notes
The potential for Impact Area Modifications to reduce the undesirable ef-
fects of wet weather sources is considered at this point in the load re-
duction strategy evaluation. The use of In-stream Reaeration and Low-Flow
Augmentation are not relevant to the control of a wet weather source. How-
ever, Discharge- Relocation is potentially viable. This evaluation would be.
identical to that for a dry weather source; therefore, the worksheets are
not included here.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
1
3
Page taa
6-360
-------
Illustrative Example Supplemental Notes
The planner would generally continue the analysis of Load Reduction
Strategy 9 at this point by considering £or"Source 4 the various control
alternatives just described for Source 3. The user is referred to the
previous worksheets for illustration of the appropriate methodologies.
By
Checked by
Rema rks :
Date
Date
Strategy No.
Source No.
*
V
Page )
-------
Illustrative Example Supplemental Notes
Following the evaluation of control alternatives for all sources identified
in Load Reduction Strategy 9, the user would consider the effect of region-
alized facilities on total project cost. The worksheets for this evaluation
are not included for this example because all of the component methodologies
have been previously utilized.
The evaluation of regional facilities for this example would include wet
and dry weather sources. In addition, the residual disposal portion of the
REGIONALIZATION METHODOLOGY would be useful in identifying effective alter-
natives.
BY
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
4
/,2j3,*V
Page \i»4
6-362
-------
Illustrative Example Supplemental Notes
At this point, the user will have completed the development and evaluation
of feasible control alternatives for the load reduction strategies of in-
terest. The total monetary cost of each control alternative will have been
developed and expressed as a Present-Worth cost. Also, a relative infor-
mation reliability will have been determined for each control alternative.
The user is now ready to evaluate criteria other than monetary cost, such
as implementability and environmental, social, and economic costs, in order
to determine which load reduction strategy has the least total cost to
society. This part of the evaluation leading to final selection is not
covered by this manual. However, the monetary costs calculated using this
manual are a major input to that determination.
By
Checked by
Remarks:
Date
Date
Strategy No.
Source No.
M/A
*J/A
Page 1-2. A"
6-363
-------
6.6 References
1. Water Quality Criteria, Report of National Technology Advisory Committee
to Secretary of the Interior, F.W.P.C.A., Washington, D.C. (April 1968).
2. Environmental Protection Agency, Development and Application of a
Simplified Stormwater Management Model, EPA-600/2-76-218, August, 1976.
3. Environmental Portection Agency, Dispatching Systems for Control of
Combined Sewer Losses, 11020FAW03/71, March, 1971.
4. Environmental Protection Agency, Maximizing Storage in Combined Sewer
Systems, 11022ELK12/71, December, 1971.
5. Environmental Protection Agency, Combined Sewer Overflow Abatement
Technology, 11024—06/70, June, 1970.
6. Environmental Protection Agency, Computer Management of a Combined
Sewer System, EPA-670/2-74-022, February, 1974.
7. Environmental Protection Agency, Sewerage System Monitoring and Remote
Control, EPA-670/2-75-022, February, 1975.
8. Environmental Protection Agency, Urban Runoff Pollution Control
Technology Overview, Field, R., Talfuri, A.N., and Masters, H.E.,
September, 1976.
9. Environmental Protection Agency, Urban Stormwater Management and
Technology - An Assessment, EPA-670/2-74-040, December, 1974.
10. Environmental Protection Agency, Stormwater Management Model Level I -
Preliminary Screening Procedures, EPA-600/2-76-275, October, 1976.
11. Environmental Protection Agency, Cost-Effectiveness Analysis of Municipal
Wastewater Reuse, WPD-4-76-01, April, 1975.
12. Environmental Protection Agency, Guidance for Preparing a Facility Plan,
• revised May, 1975.
13. Environmental Protection Agency, "Grants for Construction of Treatment
Works, Appendix A of Cost-Effectiveness Analysis Guidelines", draft
regulations, 40 CFR 35, February 4, 1977.
14. Environmental Protection Agency,- Wastewater Treatment and Reuse by
Land Application, 2 volumes, EPA-660/2-73-006, August, 1973.
15. Environmental Protection Agency, Land Applications of Sewage Effluents
and Sludges: Selected Abstracts, EPA-660/2-74-042, June, 1974.
16. Environmental Protection Agency, Evaluation of Land Application Systems,
Technical Bulletin, EPA-430/9-75-001, March, 1975.
6-364
-------
11 ^Bv/
17. Environmental Protection Agency, Costs of Wastewater Treatment by
Land Application, Technical Report, EPA-450/9-75-005, June, 1975.
18. Environmental Protection Agency, Cost-Effective Comparison of Land
Application and Advanced Wastewater Treatment, Technical Report
EPA-430/9-75-016, November, 1975.
19. Environmental Protection Agency, "Use of Low Flow Augmentation by Point
Sources to Meet Water Quality Standards", Memorandum dated November 8,
1976.
20. Grant, Eugene L. and W. Grant Ireson, Principles of Engineering Economy,
Ronald Press, New York, 1970.
21. Environmental Protection Agency, Wastewater Sludge Utilization, Technical
Report, EPA-430/9-75-015, September, 1975.
22. Environmental Protection Agency, Technical Bulletin on Municipal Sludge
Management: Environmental Factors, soon to be published.
23. Environmental Protection Agency, Municipal Sludge Management: EPA
Construction Grants Program, An Overview of the Sludge Management
Situation, EPA-450/9-76-009, MCD-30, April, 1976.
24. Environmental Protection AGency, Application of Sewage Sludge to Crop
land: Appraisal of Potential Hazard of the Heavy Metals to Plants and
Animals, EPA-430/9-76-013, MCD-33, November, 1976.
6-365
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