United States Office of Water EPA 570/9-91-023
Environmental Protection (WH-550) October 1991
Agency
MAN AGING GROUND
WATER CONTAMINATION
SOURCES IN WELLHEAD
PROTECTION AREAS: A
PRIORITY SETTING APPROACH
Printed on Recycled Paper
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MANAGING GROUND WATER CONTAMINATION SOURCES
IN WELLHEAD PROTECTION AREAS:
A PRIORITY SETTING APPROACH
Office of Water
U.S. Environmental Protection Agency
October 1991
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ACKNOWLEDGEMENTS
This document was prepared by the U.S.
Environmental Protection Agency, Office of Ground
Water and Drinking Water under contract No. 68-
CO-003. Erin K. Flanagan served as the task
manager for this project, with assistance from Janette
E. Hansen and Dr: Norbert Dee. "
We would like to give special thanks to the
following people for field testing the system during
the peer review process:
Gary E. Beck, Olean, New York
Ron Disrud, Rolla, North Dakota
Jennifer Fais, Prattsburg, New York
Bob Lowe and Mark Jensen, Salt Lake City,
Utah
Katie Luther, Bismark, North Dakota.
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EXECUTIVE SUMMARY
The 1986 Amendments to the Safe Drinking Water Act established a new Wellhead
Protection Program for ground waters that supply drinking water to public systems. Managing
Ground Water Contamination Sources in Wellhead Protection Areas: A Priority Setting
Approach is one of a series of technical assistance documents designed by the U.S.
Environmental Protection Agency to help local governments and public water suppliers protect
their wells and implement their state and local Wellhead Protection Programs.
This Priority Setting Approach provides a risk screening tool that helps users to assess and
rank the relative threats to ground-water supplies posed by specific potential contamination
sources that fall into any of the following major source categories: Agrichemical Application,
Container Storage and Material Transfer, Injection Wells: Deep Wells (Classes I, II, and III),
Injection Wells: Shallow Wells (Class V), Land Treatment, Landfills, Material Transport,
Pipelines, Septic Tank Systems, Storage Piles, Surface Impoundments, and Tanks.
This Approach allows the estimation of the human health risks posed by a contamination
source. The user calculates a risk score for each potential contaminant by multiplying two
components of risk:
»• Likelihood of Well Contamination: the probability that the contaminant will be
released from the source and will reach the well within a user-specified planning
period. This is a function of two risk elements: Likelihood of Release at the Source
(how likely is it that the contaminant will be released from the source into the soil
underlying the source) and Likelihood of Reaching the Well (if the contaminant is
released, how likely is it to reach the well within the planning period?).
K Severity of Well Contamination:. For a given contaminant at.a given source, the
Severity of Well Contamination is the carcinogenic or non-carcinogenic risk to an
individual drinking water from the well in the event contaminants are released and
reach the well. This is a function of three risk elements: Quantity released at the
source (what is the amount of contaminant expected to be released from the source?),
Attenuation due to transport (what fraction of the contaminant released will reach the
well and at what concentration?) and Toxicity (how toxic is the contaminant? For
carcinogens, the lower the concentration of a chemical resulting hi a 10"5 lifetime risk,
the higher the toxicity of that chemical. For non-carcinogens, the lower the
concentration threshold of a chemical (the point above which adverse health effects are
exhibited), the higher the toxicity of that chemical.
This Approach allows the user to compare the Likelihood and Severity of well
contamination from one source, as well as the Likelihood and Severity of well contamination
from different sources. The overall risk score for a given source is the highest of the risk
scores associated with all contaminants present at the source.
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CONTENTS
Chapter 1: Introduction 1
About This Manual 2
What Is the Priority Setting Approach? 2
Who Is This Manual Intended For? " . - - -2-
How Can It Help You? 2
What Will It Do? 3
What Won't It Do? 3
What Is Needed to Use This Manual? 3
What Does the Priority Setting Approach Assume? 4
How Does the Priority Setting Approach Work? 5
How Can the Results Be Used? . 8
The Organization of This Manual 9
Chapter 2: User's Guide 11
Using the Priority Setting Approach 12'
Tasks You Need to Perform . 12
Using the Datasheets and Worksheets 13
Using Defaults ,, 17
General Guidance for Each Task 19
Task I: Characterize Your WHPA 21
Task II: Identify and Characterize Potential Sources of Well Contamination 23
Task III: Perform Source Calculations 29
Task IV: Perform Transport Calculations 30
TaskV: Estimate Risks and Rank Sources 31
Using the Risk Matrix: An Example 35
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CONTENTS _ • _ iy
Hypothetical Example of Using the Priority Setting Approach 39
The Scenario 30,
Task I: Characterize Your WHPA 39
Task II: Identify and Characterize Potential Sources of Well Contamination 41
Task III: Perform Source Calculations 43
Task IV: Perform Transport Calculations 44
TaskV: Estimate Risks and Rank Sources 45
Chapter 3: Master Scoresheet, Wellhead Datasheet, Risk Matrix, ^ .
and Contaminant Forms 95
Master Scoresheet 97
Wellhead Datasheet '99
Risk Matrix JQC
Contaminant Forms 1Q7
Contaminant Form SI
Contaminant Form S2
Chapter 4: Source Datasheets, Source Worksheets, and Transport Worksheet 141
Agrichemical Application 143\
Container Storage and Material Transfer 151
Injection Wells: Deep Wells (Classes I, II, and III) . 159
Injection Wells: Shallow Wells (Class V) .
Land Treatment
Landfills
Material Transport
Pipelines 203
Septic Tank Systems 211
Storage Piles 219
Surface Impoundments . 229
Tanks 237
Transport Worksheet 247
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CONTENTS
Technical Appendix A: Systern Assumptions and Limitations of
The Priority Setting Approach 257
Technical Appendix B: Conceptual Overview of the
Priority Setting Approach 265
Bibliography 273
Acronyms, Symbols, and Definitions 281
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CHAPTER!: INTRODUCTION
Managing Ground Water Contamination Sources in Wellhead Protection Areas: A Priority
Setting Approach is one of a series of technical assistance documents designed to help local
governments and public water suppliers protect their wells and implement their state and local
Wellhead Protection Programs. The purpose of this Approach is to assess the relative threats to
ground-water supplies from different contamination sources.
The 1986 Amendments to the Safe Drinking Water Act (SOWA) established a new
Wellhead Protection Program to protect ground waters that supply drinking water to public
water supply systems. This program requires the participation of all levels of government.
The federal government is responsible for approving state Wellhead Protection Programs
and for providing technical support to state and local governments. States must develop and
implement programs that meet the requirements of the SOW A Amendments. At a minimum, a
state's Wellhead Protection Program must:
>• specify the roles of the state and local entities with wellhead protection duties
+ delineate the wellhead protection area (WHPA)* for each well
»• develop management approaches to protect each WHPA
>• develop contingency plans to respond to well or wellfield contamination
>• site new wells properly to minimize potential contamination
>• ensure public participation in the program.
Because localities are often in the best position to implement measures to ensure that individual
wells and wellfields are properly protected from contamination, the U.S. Environmental
Protection Agency has prepared this manual for use at the local level.
This manual can help local users evaluate and rank the risk to their public water supply
from potential contamination sources in their wellhead protection areas. While it is important
to manage all sources within a WHPA, it is sometimes necessary for communities to prioritize
their activities. In addition to providing an approach to risk screening, this manual can be
helpful in making siting decisions, in evaluating the relative risk of different design factors, and
in assessing the general vulnerability of a WHPA.
* A wellhead protection area is defined as "the surface and subsurface area surrounding a
water well or wellfield, supplying a public water system through which contaminants are likely
to move toward and reach such well or wellfield" (ref. 47). The extent of the protection area is
determined by state guidelines in states with approved programs.
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INTRODUCTION
ABOUT THIS MANUAL
What Is the Priority Setting Approach?
This Approach is a risk screening tool that will enable you to assess the risks posed by
specific potential sources of contamination. Risk screening is a simplified form of risk
assessment that uses limited data to yield a relative expression of risk. Using this Approach,
you will be able to assess potential sources of contamination that fall into any of the following
major source categories:
1. Agrichemical Application - " "
2. Container Storage and Material Transfer
3. Injection Wells: Deep Wells (Classes I, II, and III)
4. Injection Wells: Shallow Wells (Class V)
5. Land Treatment
6. Landfills
7. Material Transport
8. Pipelines
9. Septic Tank Systems
10. Storage Piles
11. Surface Impoundments
12. Tanks.
Who Is This Manual Intended For?
This manual is designed to be used by local managers such as city planners, water supply
superintendents, and local health and environment department officials. You do not need
computer or modeling experience, nor will you require extensive training or study before you
can use this manual.
How Can It Help You?
When managers are assessing the threats to public water supply, it is often difficult to
determine which of the many potential contamination sources poses the greatest risk to a well.
Although it is possible to conduct detailed risk assessments of all the potential sources, such
assessments require a large amount of information and extensive resources that are not
generally available to managers at the local level.
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INTRODUCTION
This manual addresses these concerns by allowing you to screen potential contamination
sources on the basis of risk, using readily available information. It thus helps local managers to
prioritize their management efforts as well as explain their actions to the public.
What Will It Do?
This manual will help you determine a risk score for each potential source of
contamination. Based on the risk scores, you will be able to:
>• Rank sources (assess whether one source poses a greater risk than another
source)
>• Screen sources (determine whether a given source poses a high, medium, or
low level of risk). •
What Won't It Dp?
There are limits to the rankling and screening capabilities of this Approach which need to
be kept in mind. It is not:
> a substitute for site-specific, detailed risk assessments
> a comprehensive screening system for all possible contamination sources or
contaminants, or all possible routes of exposure to contaminants (ingestion is
the only route considered)
> a technique for analyzing management approaches.
What Is Needed to Use This Manual?
To use this manual, you will need to have on hand, or have access to, basic information
about the location of the well, the WHPA, and the potential contamination sources; the WHPA
hydrogeology; and the characteristics of the potential sources of contamination. The following
chart summarizes the information needed to use this manual.
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INTRODUCTION
Major Information Needs
Locations!
Information
Hydrogeology and
Well Information
Source-Specific
Information
> map showing the
wellhead protection area
boundaries
»• map showing the
location of potential
contamination sources
»• depth to the aquifer
>• aquifer thickness
+ type of soil above the
,- water table (e.g., silt or
sand) and aquifer
material (e.g., sand or
gravel)
»• basic design features
(e.g., type of landfill
liner)
* distance from well
»• contaminants present
(defaults provided)
What Does the Priority Setting Approach Assume?
As you use this manual, you need to ensure that your WHPA and your sources satisfy the
assumptions built into this Approach; if they differ substantially from these assumptions, you
will not be able to use this manual for screening and ranking sources in your WHPA. Some of
the major assumptions and limitations built into this Approach are summarized below:
> Hydrogeologic Characteristics. The hydrogeologic characteristics in the
WHPA are assumed to be relatively homogeneous and isotropic. In other
words, it is assumed here that you can characterize the WHPA by one average
value for each of the following parameters: depth to aquifer, aquifer thickness,
hydraulic conductivity in the unsaturated zone, and ground-water velocity. If
the hydrogeologic characteristics vary significantly within your WHPA, you
cannot use this manual to rank and screen potential contamination sources.
For example, if the depth to the aquifer is 10-^feet under source A and 150 feet
under source B, then you cannot use this Approach as it is currently configured
because it assumes one average value for depth to aquifer.
»• Hydrogeologic Setting. One of four basic hydrogeologic settings is assumed:
— surface source overlying a water table aquifer
deep source (Class I, II, and III injection wells) with accidental releases
in a confined aquifer
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INTRODUCTION
— surface source in a recharge area of a confined aquifer
surface source overlying a confined aquifer.
>• Zone of Contribution. It is assumed that the contaminants released from each
source inside the WHPA can reach the well. This Approach does not
distinguish explicitly between sources that are upgradient from the well and
sources that are downgradient from the well. Thus, this Approach may
overestimate risks posed by sources that are downgradient from the well
because these contaminants can be expected to flow away from the well.
* Carcinogenic and Non-Carcinogenic Risks. You can use this manual to
screen and rank sources based on carcinogenic and non-carcinogenic risks,
either together (only one risk score for each source) or separately (two risk
scores for each source). It has a built-in formula so that it is not necessary to
consider carcinogenic and non-carcinogenic sources separately. Specifically,
this Approach equates a 10'5 (1 in 100,000) cancer risk with a lifetime exposure
to the reference dose for non-carcinogens. Other environmental programs use
different levels of acceptable cancer risk. Most commonly, they range from 1
in 10,000 (10-4) to 1 in 1,000,000 (Itf6). For information on how to modify
this assumption, see Technical Appendix A.
> Human Exposure. This manual assumes that human populations will be
exposed to the contaminants released by potential sources only through the
consumption of contaminated drinking water. It does not consider exposure to
contaminants through any other pathways such as inhalation or dermal contact.
For a more detailed discussion of the assumptions and limitations, and the hydrogeological
settings used in this manual, please refer to Technical Appendix A.
How Does the Priority Setting Approach Work?
As a risk screening tool, this Approach relies on the general principles of risk assessment,
but requires less data and provides a less rigorous analysis than a formal risk assessment. It
integrates information from several EPA data bases and models such as the IRIS data base for
toxicity information, the RCRA Risk-Cost Analysis Model (or WET model), the Liner Location
Model, and the Hazardous Waste Tank Failure model for information on the potential for
contaminant release.
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INTRODUCTION
This Approach allows you to estimate the human health risks posed by a contamination.
source. You obtain the risk score by multiplying two risk components:*
»• Likelihood of Well Contamination and
> Severity of Well Contamination in the event contaminants are released and
reach the well. .
For a given contaminant at a given source, the Likelihood of Well Contamination is the
probability that the contaminant will be released from the source and will reach the well within
the planning period you specify (e.g.-, 10 years). The Likelihood of Well Contamination (L) is
a fimction of two risk elements:
1. Likelihood of Release at the Source (LI), that is, how likely is it that the
contaminant will be released from the source into the soil underlying the
source?
2. Likelihood of Reaching the Well (LJ, that is, if the contaminant is released,
how likely is it to reach the well within the planning period of interest?
For a given contaminant at a given source, the Severity of Well Contamination is the
carcinogenic or non-carcinogenic risk to an individual drinking water from the well. The
Severity of Well Contamination (S) is a function of three risk elements:
1. Quantity released at the source (Q), that is, what is the amount of contaminant
expected to be released from the source?
2. Attenuation due to transport (A), that is, what fraction of the contaminant
released will reach the well and at what concentration?
3. Toxicity (T), that is, how toxic is the contaminant? For carcinogens, the lower
the concentration of a chemical resulting in a 10"5 lifetime risk, the higher the
toxicity of that chemical. For non-carcinogens, the lower the concentration
threshold of a chemical (the point above which adverse health effects are
exhibited), the higher the toxicity of that chemical.
The scores for each of these risk components can be plotted on a conceptual diagram of
the Risk Matrix shown in Exhibit 1. This exhibit enables you to visualize the relationship
* For a further explanation of this equation, see "A Note on Negative Scores" on page 29.
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Exhibit 1
Conceptual Diagram of the Risk Matrix
Likelihood
of
Release
Likelihood
of Reaching
the Well
Likelihood
+ of Well
Contamination
Quantity
1
Toxicity
!
Attenuation
1
T
Severity of Well Contamination
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INTRODUCTION
between the Likelihood and Severity of Well contamination from one source, as well as to
compare the Likelihood and Severity of Well contamination from different sources.
The overall risk score for a given source is the highest of the risk scores associated with all
contaminants present at the source. Technical Appendix B provides a conceptual overview of
this process.
How Can the Results Be Used?
You can use the results.of this .Approach to assist in management activities, including:
»• prioritizing source management efforts (e.g., site inspection, monitoring,
enforcement, education, data collection)
*• planning and zoning aimed at controlling the siting of new potential
contamination sources
>• conducting vulnerability assessments under the Public Water Supply
Supervision Program.
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INTRODUCTION
THE ORGANIZATION OF TfflS MANUAL
This manual contains all of the guidance, datasheets, and worksheets necessary to
systematically perform a site-specific risk screening and ranking of contamination sources in 12
major source categories. The remainder of this manual is organized as follows:
Chapter 2: User's Guide
This chapter provides you with general guidance on completing five major tasks necessary
to characterize the risk posed by the contamination sources. These tasks are to: (1)
characterize the WHPA, (2) characterize the potential contamination sources, (3) perform
source-specific calculations, (4) perform transport calculations, and (5) estimate risks and rank
sources. You complete these tasks by filling out the datasheets, worksheets, master scoresheet,
and risk matrix contained in Chapters 3 and 4 of this manual. This chapter also presents a
hypothetical example of the applying this Approach.
Chapter 3: Master Scoresheet, Risk Matrix, Wellhead Datasheet, and Contaminant
Forms
This chapter contains the sheets that you will fill out to assess the WHPA. Also contained
in this chapter are the contaminant forms. These forms provide information you will need for
scoring the toxicity, mobility, and persistence of the contaminants associated with each source
category.
Chapter 4: Source Datasheets, Source Worksheets, and Transport Worksheet
4
This chapter contains the datasheets and worksheets that you will fill out for each source
that is evaluated. Datasheets and worksheets are included for the following major
contamination source categories, listed in alphabetical order:
1. Agrichemical Application
2. Container Storage and Material Transfer
3. Injection Wells: Deep Wells (Classes I, II, and III)
4. Injection Wells: Shallow Wells (Class V)
5. Land Treatment
6. Landfills
7. Material Transport
8. Pipelines
9. Septic Tank Systems
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INTRODUCTION 10
10. Storage Piles
11. Surface Impoundments
12. Tanks.
This chapter also contains the Transport Worksheet. This worksheet must be
completed once for each source in order to evaluate the fate and transport of contaminants
released by that source.
Appendices
The remainder of this manual contains two technical appendices, references, and a
glossary. Technical Appendix A presents a detailed discussion of the assumptions and
limitations of the Priority Setting Approach, and Technical Appendix B provides a conceptual
overview of this Approach and its risk scoring system. The glossary of technical terms can
assist readers who may not be familiar with all of the terms used in this manual.
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11
CHAPTER 2: USER'S GUIDE
This chapter describes the basics of this Priority Setting Approach. The introductory
section presents an overview of this Approach's five tasks, and describes how to use the
datasheets and worksheets. It also describes the default values provided for certain parameters
in the datasheets and worksheets. You can use these average values when site-specific values
are difficult to obtain. The next section provides general guidance on how to complete each of
the five tasks and the specific steps to be taken under each task. The last section presents a
hypothetical example of how to apply this Approach. - -
This manual is organized in chapters that can be removed from this binder to permit easier
access to the data contained in other sheets. You should read this chapter (the User's Guide) at
least once to familiarize yourself with this Approach before you begin completing the sheets in
Chapters 3 and 4.
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USER'S GUIDE
USING THE PRIORITY SETTING APPROACH
This Priority Setting Approach contains five major tasks; within these tasks are 12 specific
steps. When working through the tasks, you will complete a wellhead datasheet, source
datasheets and worksheets, and transport worksheets. These datasheets and worksheets, in
turn, will be used to complete a master scoresheet and finally, the risk matrix.
Tasks You Need to Perform
This manual helps you to evaluate the risks posed by potential sources of well
contamination By guiding you through the following tasks:
Task! Characterize Your WHPA
Task H Identify and Characterize Potential Sources of Wellhead Contamination in
Your WHPA
Task III Perform Source Calculations
Task IV Perform Transport Calculations
Task V Estimate Risks and Rank Sources
In Task I, you will locate your WHPA on a map and characterize its hydrogeology In
Task II, you will identify all potential sources of wellhead contamination (e.g., landfill, storage
pile) in your WHPA and characterize each source by a number of elements including its design,
age, distance from the well, and contaminants or contaminant mixtures present (including
toxicity). In Tasks III and IV, you will estimate the following risk elements for each
contaminant or contaminant mixture .present at each potential source:
> the likelihood of the contaminant/mixture being released and the quantity of
contaminant/mixture released (Task III)
* the likelihood that the contaminant/mixture will reach the well if it is
released, and its attenuation (the fraction of the contaminant/mixture that will
reach the well after dilution and/or chemical breakdown) (Task IV).
In Task V, you will estimate the risk posed by each potential source of well contamination by
aggregating the contaminant-specific elements of risk estimated in Tasks III and IV. This will
allow you to rank and screen the potential sources of well contamination in your WHPA on the
basis of risk.
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USER'S GUIDE 13
Using the Datasheets and Worksheets
To perform the five tasks, it is necessary to complete datasheets, worksheets, a master
scoresheet, and a risk matrix. In addition, contaminant forms are provided to help you fill out
the datasheets.
»• Datasheets. Two types of datasheets are provided. The Wellhead Datasheet
is used to characterize the hydrogeology within your WHPA (Task I) and as a
reference in completing Tasks III and IV. A Source Datasheet is provided
for each of the 12 source categories. It is used to characterize the source
(Task II) and as a reference-in Tasks III and IV.
>• Contaminant Forms. These forms provide contaminant-specific information
necessary to complete the contaminant data tables contained in all of the
Source Datasheets. They do not need to be filled out; rather, they are used
as a reference in completing the datasheets in Task II.
>• Worksheets. Two types of worksheets are provided. One Source
Worksheet, like the Source Datasheet, is provided for each source category.
It is used to determine the likelihood that a contaminant/mixture will be
released and (he expected quantity released (Task III). The Transport
Worksheet is used to determine the likelihood that the contamination will
reach the well and the attenuation of the contaminant (Task IV).
> Master Scoresheet. This scoresheet compiles the information gathered in
Tasks II through IV in order to estimate risks and rank the sources.
-> Risk Matrix., This matrix allows you to estimate the human health risks
posed by the contaminants at each source (Task V). You will complete the
Risk Matrix using the information in the Master Scoresheet to plot the
likelihood of well contamination against the severity of well contamination.
Exhibit 2 illustrates the use of these sheets by task. An example of how to use these sheets is
given on page 15.
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14
Exhibit 2
Using the Datasheets and Worksheets by Task
Task I: Characterize
YourWHPA
Wellhead
Datasheet
Task II: Identify and
Characterize Potential
Sources of Well
Contamination
Source
Datasheet
Task III: Perform
Source Calculations
Source
Worksheet
Task IV: Perform
Transport Calculations
Transport
Worksheet
TaskV: Estimate
Risks and Rank
Source
Master
Scoresheet
J
Risk
Matrix
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USER'S GUIDE 15
Example of Using Datasheets and Worksheets
Assume that you are estimating the risk posed by a landfill located within your
WHPA. You will first complete the Wellhead Datasheet to characterize the
hydrogeology of your WHPA (Task I). Note that you will need to perform this
first task only once, regardless of how many sources you have in your WHPA.
You will then report the name of your landfill and assign it an identification
number in Block I of the Master Scoresheet, and characterize the landfill by
completing the Landfill Datasheet (Task II). To complete this datasheet, you will
refer to the contaminant forms. Next, you will complete the Landfill Worksheet
(Task III) and the Transport Worksheet (Task IV) for your landfill, and report the
estimates of the risk elements in Block II of the Master Scoresheet. Finally, you
will estimate the risk posed by your landfill by completing Block III of the Master
Scoresheet, and plot the risk scores of the landfill on the Risk Matrix (Task V).
For a complete illustration of how to use these sheets, see the example provided in
the last section of this chapter.
Exhibit 3 summarizes the sheets used in each task and the chapters in which they are
located. It highlights the sheets that need to be completed in each task (task sheets) and the
sheets that you need to refer to in each task (reference sheets).
As this exhibit shows, you will often use Chapters 3 and 4 simultaneously. In Task IV, for
example, you will need information from the Wellhead Datasheet, which is contained in
Chapter 3, and the Source Datasheet, which is contained in Chapter 4. These will be used to
complete the Transport Worksheet, which is also contained in Chapter 4. In addition, you will
sometimes need to move back and forth between sheets. For example, as you complete the
Transport Worksheet for one source, you will need information from the corresponding Source
Datasheet, both of which are contained in Chapter 4.
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USER'S GUIDE
16
Exhibits
Tasks and Their Associated Sheets and Locations
^"•^^•^•^••^•••^•H
Task
I. Characterize Your
WHPA
II. Identify and
Characterize
Potential Sources of
Well Contamination
III. Perform Source
Calculations
IV. Perform Transport
Calculations
V. Estimate Risks and
Rank Sources
*———mmi^
•••^^•HMMWIM
Reference Sheets
(provide information to
perform the task)
Name
—
Contaminant Forms
Wellhead Datasheet
Source Datasheets
Wellhead Datasheet
Source Datasheet
^^•^•MlMiMM
Location
—
Chapter 3
Chapter 3
Chapter 4
Chapter 3
Chapter 4
MMMMMI
———nm-mm—m^n
Task Sheets
(sheets completed in order to
perform the task)
Name
Wellhead Datasheet
Master Scoresheet
Source Datasheets
Source Worksheets
Master Scoresheet
Transport Worksheet
Master Scoresheet
Master Scoresheet
Risk Matrix
MMBMIMil^HMHMI
Location
Chapter 3
Chapter 3
Chapter 4
Chapter 4
Chapter 3
Chapter 4
Chapter 3
Chapter 3
Chapter 3
^•^••^•^•i
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USER'S GUIDE 17
A NOTE ON COPYING THE DATASHEETS AND WORKSHEETS
Before you fill out these sheets, you should make as many photocopies of them as you need
in order to evaluate all of your sources.
+ Wellhead Datasheets. Make one copy for each WHPA.
> Transport Worksheets. Make as many copies of these worksheets as there are
sources in your WHPA.
> Source Datasheets and Source Worksheets. For each source category (e.g.,
landfills and septic tanks), have as many copies of these sheets as there are sources
in that source category. Thus, if your WHPA has three septic tanks systems and
one landfill, you will need three Source Datasheet/Worksheet sets for septic tanks
and one set for the landfills. If you can group clusters of the same sources (e.g.,.a
block of houses using septic tank systems), you will need to copy only one set for
that source.
i» Master Scoresheet. Make as many copies as you need to list all of your sources in
allofyourWHPAs.
You do not need to make additional copies of the other sheets.
Using Defaults , .
The datasheets and worksheefs provide default values for certain parameters. Default
values are average values that you may use if site-specific data are difficult to obtain.
Depending on the situation, the difference between a default value and the actual, site-specific
data can be significant. Thus, whenever possible, you should gather site-specific data rather
than use default values; this will ensure that you are developing a more accurate representation
of your sources.
If you are not sure which default value to use in a range of possible values, it is wise to
choose the value that will result in a higher Likelihood or Severity score in order to err on the
side of over-estimating risk. In this way, you will ensure that you have protected the public
from the greatest risks potentially posed by a source. If you choose a default value that errs on
the side of over-estimating risk and that source finishes with a medium or high Risk score,
however, you should check the sensitivity of the risk result to that parameter. To do this, redo
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USER'S GUIDE
18
all the calculations for that source by replacing the conservative default value with a median,
default value. If the final ranking of the source changes dramatically (for example, if the
source moves from a medium or high risk to a low risk), then you should make every effort to
gather more accurate, site-specific data for that parameter in order to determine a better risk
estimate for that source.
Last, if the datasheets and worksheets do not provide a default value for a given parameter
and no site-specific data are available for that parameter, you may want to consult with other
officials or industry representatives who may have that information. If you are still unable to
obtain a range of possible values for that parameter, then you cannot use the Priority Setting
Approach. .
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USER'S GUIDE 19
GENERAL GUIDANCE FOR EACH TASK
Within each of the five tasks are two or three steps that you must perform in sequence in
order to complete the task. There are a total of 12 steps for the five tasks. Exhibit 4 provides
an overview the tasks and steps contained, in this Approach.
This section provides general guidance on how to complete the Priority Setting Approach.
The guidance given here is not comprehensive. Instead, it is intended to give basic
instructions, to help you with those steps requiring decisions and judgment, and to provide you
with sources of additional information. More specific instructions on how to complete each
step are contained in the datasheets and worksheets in Chapters 3 and 4. The hypothetical
example of using this Approach, which is presented in the next section, will also assist you in
completing this Approach.
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I: Characterize Your WHPA
Exhibit 4
Overview of the Priority Setting Approach
1: Map WHPA boundaries
2: Characterize WHPA
hydrogeology
"F"| Wellhead Datasheet |
20
—'—•""••'•-•-•l^«H^••••^^•
II. Identify and Characterize
Potential Sources of Well Contamination
4: List sources by
category and name
5: Characterize potential
contamination sources
I III: Perform Source Calculations
6: Assess contaminant
releases from the source
7: Transfer scores to
Master Scoresheet
IV: Perform Transport Calculations
8: Assess contaminant
transport
9: Transfer scores to
Master Scoresheet
V: Estimate Risks and Rank Sources
10: Determine contaminant-
-specjiic risk scores
11: .Determine source-
specific overall risk scores
I 12; Plot each source |
3: Identify and locate all sources
^ Source Datasheet [
•fr I Source Datasheet
*
^ Transport Datasheet [
Master
Scoresheet
Block!
Block n
Block n
-i--
Block HI
Block m
Risk Matrix
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USER'S GUIDE
21
Task I: Characterize Your WHPA
Steps
Name and Location of
Data Entry Sheets
1. Map WHPA boundaries
2. Characterize WHPA hydrogeology
Wellhead Datasheet (Chap. 3)
Step 1 Guidance: Map WHPA Boundaries
> Identify the boundaries of your WHPA on a map. It is assumed here that all contaminants
introduced within the boundaries of the WHPA could reach the well. For more
information on delineating WHPAs, see: U.S. Environmental Protection Agency, Office
of Ground-Water Protection, Guidelines for Delineation of Wellhead Protection Areas,
Washington, D.C., 1987. Before determining which delineation method to use for your
WHPA, check witfi your suite environmental protection agency for recommended methods
or thresholds.
Step 2 Guidance: Characterize WHPA Hydrogeology
The Approach assumes that hydrogeologic features of the WHPA are relatively
homogeneous and that the WHPA is inside the zone of contribution to the well (the area
surrounding the well that supplies groundwater to the well). If actual conditions vary
significantly from these assumptions, then you cannot use this manual to rank and screen
potential contamination sources (for more details on this, see "What Does the Priority Setting
Approach Assume" in Chapter 1).
»- Photocopy one Wellhead Datasheet (Chapter 3) for each WHPA for which you will apply
this Priority Setting Approach.
> Characterize the hydrogeology of the WHPA by completing the Wellhead Datasheet. You
will only need to complete this datasheet once for each WHPA. You will use the data
from the Wellhead Datasheet to complete the Transport Worksheet in Task IV (this
datasheet is sometimes used in Task III as well).
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USER'S GUIDE 22
> For the Planning Period (parameter WDl on the Wellhead Datasheet), enter the number of
years, from now into the future, over which you are concerned with the possibility of
contamination of the wellhead. You may select a short-term planning period (e.g., 10
years) or a long-term planning period (e.g., 100 years). The Planning Period should be no
less than the expected life of the wellfield in which the well is located. The Planning
Period affects the calculation of the Likelihood of Reaching the Well (Lj, see Transport
Worksheet, Task IV). Other things being equal, the longer the planning period, the higher
the likelihood that contaminants released at the source will reach the well within the
Planning Period considered.
» If the WHPA is located in a confined aquifer, then you will measure the depth to the -
aquifer from the source to the top of the confined aquifer, and not to the potentiometric
surface. (For more details on this, see Technical Appendix A, "Hydrogeologic Setting.")
> You can determine the unsaturated zone Hydraulic Conductivity Score (WD5) in either of
two ways. If you know the hydraulic conductivity of the unsaturated zone, then refer to
Table W.2. If you do not know the hydraulic conductivity, then use Table W.3 to
determine it as a function of the type of material in the unsaturated zone. If you use Table
W.3, do not choose Clay or Karst unless these materials comprise at least 70 percent of
the entire unsaturated zone. If clay or karst do not comprise at least 70 percent of the
material in the unsaturated zone, then choose the most appropriate material type from the
following three categories: Clayey-Silt or Silt, Silty-Sand or Sand, or Sandy-Gravel or
Gravel. Select the category that represents the most prevalent mix of materials throughout
the unsaturated zone. For example, loam soils, a prevalent soil class, typically contain
approximately 7 to 27 percent clay, 28 to 50 percent silt, and less than 52 percent sand
(see reference 3 in the bibliography). Therefore, if your unsaturated zone consists of
loam soils, then the material type is either Clayey-Silt or Silt, or Silty-Sand or Sand. The
material type will be Clayey-Silt or Silt if clay and silt make up more than 50 percent of
the entire unsaturated zone. Conversely, the unsaturated zone material type will be Silty-
Sand or Sand if it consists primarily (i.e., more than 50 percent) of silt and sand.
• One very good source of information on the type of material in the unsaturated zone is a
soil survey map, which is available from your county Soil Conservation Service office.
These maps diagram the various soil types that exist in a particular county and can be used
to project the type of materials that exist in the unsaturated zone.
Another source of information is well drillers' logs. A driller's log is prepared by a well
drilling crew and describes the geologic material encountered while digging the well.
However, the information in a driller's log is often unreliable and should be used only to
refine data from soil survey maps.
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USER'S GUIDE 23
Task II: Identify and Characterize Potential Sources of Well Contamination
Steps Name and Location of
Data Entry Sheets
3. Identify and locate all sources :;
4. Identify and list all sources by source category and name Block I of fine Master
Scoresheet (Chap. 3)
5. Characterize potential contaminants v-
Source Datasheets
(Chap. 4)
Step 3 Guidance: Identify and Locate All Sources
> Identify the potential sources of ground-water contamination (see Exhibit 5) that are within
the boundaries of the WHPA. You may also include sources located beyond the limits of
your WHPA if you have any reason to believe that contaminants released from those
sources could reach the well. For more assistance on how to identify sources of potential
contamination, see: U.S. Environmental Protection Agency, Office of Ground Water and
Drinking Water, A Guide for Conducting Contamination Source Inventories for Public
Drinking Water Supply Protection Programs, Washington, D.C., 1991.
>• When identifying sources, keep in mind that one facility may have many different sources.
For example, a gasoline/service station may have an underground storage tank and a
shallow injection well (e.g., an automobile service station disposal well). In such cases,
you need to identify and analyze each different source separately. You may, however,
want to group similar sources and analyze them as one source, as discussed next.
> To help you visualize the location of potential sources of contamination relative to the
well, it is helpful to locate these sources on a map.
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Exhibits
Sources and Source Categories
24
Sources (in alphabetical order)
Aboveground storage tanks:
hazardous and non-hazardous waste treatment
hazardous and non-hazardous waste storage
hazardous and non-hazardous material storage
Source Categories
Tanks
Animal feedlots
Surface Impoundments
Containers:
hazardous and non-hazardous waste storage
hazardous and non-hazardous material storage
Container Storage and Material
Transfer
Deep injection wells:
wastewater disposal wells
oil and gas activity disposal wells
mineral extraction disposal wells
Injection Wells: Deep Wells
(Classes I, H, and
De-icing salts storage piles
Storage Piles *
Fertilizer applications
Agrichemical Application
Graveyards
NA
Ground water/surface water cross contamination
NA
Irrigation practices (return flow)
NA
Land application:
wastewater application (spray irrigation)
wastewater byproduct (sludge) application
petroleum refining waste application
hazardous and non-hazardous waste application
Land Treatment
Landfills:
industrial hazardous and non-hazardous landfill
municipal sanitary landfill
Landfills
Material transfer operations:
hazardous and non-hazardous waste transfers
hazardous and non-iazardous material transfers
Container Storage and Material
Transfer
Materials stockpiles:
hazardous and non-hazardous material
Container Storage and Material
Transfer
Mining and mine drainage
NA
Natural leaching
NA
NA
* .
. (continued on next page)
The Priority Setting Approach is not designed to rank this source
Use of this Approach's Source Category for this source is only an approximation
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Exhibit 5 (continued)
Sources and Source Categories
25
Sources (in alphabetical order)
Open dumps
Pesticide applications
Pipelines:
hazardous and non-hazardous waste (sewers)
hazardous and non-hazardous material
Radioactive disposal sites
Salt-water intrusion
Septic tanks:
houses -
apartments
small businesses
Shallow injection wells:
agricultural drainage wells
automobile service station disposal wells
industrial process water disposal wells
Storm water drainage wells
Surface impoundments:
hazardous and non-hazardous waste
cesspools, ponds, lagoons, and other
impoundments
Transportation of materials:
hazardous and non-hazardous waste
hazardous and non-hazardous material
Underground storage tanks:
hazardous and .non-hazardous waste
treatment
hazardous and non-hazardous waste storage
hazardous and non-hazardous 'material
storage
Urban runoff
Waste tailings:
heap leaching piles
non-heap leaching piles
Waste piles:
hazardous and non-hazardous waste piles
Source Categories
Landfills*
Agrichemical Application
Pipelines
NA
NA
Septic Tank Systems
Injection Wells: Shallow Wells
(Class V)
Surface Impoundments
Surface Impoundments
Material Transport
Tanks
Surface Impoundments *
Storage Piles
Storage Piles
NA = The Priority Setting Approach is not designed to rank this source
* = Use of this Approach's Source Category for this source is only an approximation
Source: Based on data provided by the Office of Technology Assessment, U.S. Congress
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USER'S GUIDE 26
Step 4 Guidance: List Sources by Category and Name
»• For each WHPA, make as many copies of the Master Scoresheet (Chapter 3) as you need
so that you can list all your sources at all your WHPAs. The instructions below will help
you determine how many copies to make.
>• In some cases, it is more appropriate to apply the Priority Setting Approach to a group of
sources within the same source category than to consider each source individually (i.e.,
rather than complete one datasheet/worksheet pair for each individual source separately).
The source categories that allow you to group sources are Deep Injection Wells, Shallow
Injection Wells, Septic Tank Systems, and Tanks. You may group individual sources that
Jail under these source categories if the individual sources meet all of the^following three -
conditions:
(1) The individual sources must share similar design parameters (e.g., shallow
injection wells of comparable type and age).
(2) The individual sources must all be located within one of the following distance
ranges: less than one-eighth mile, one-eighth to one-quarter mile, one-quarter -
to one-half mile, one-half to one mile, one to three miles, .or three to five miles.
For example, if several product and waste storage tanks are all located between
one-quarter and one-half mile, then you may be able to cluster these tanks.
(3) The individual sources must dispose of the same or similar contaminants (e.g.,
two Class I deep injection wells that are used to dispose of both chromium and
sulfuric acid wastes).
* Use Exhibit 5 to find the source category that applies to each of your sources. For
example, Exhibit 5 directs you to use the Agrichemical Application source category if your
source is fertilizer applications. Note, that you will not be able to rank and screen certain
types of sources using this Approach. Exhibit 5 denotes these sources with an "NA" in the
second column. An asterisk (*) in Exhibit 5 denotes sources for which the source category
recommended is only an approximation. For stormwater drainage wells, for example, the
Surface Impoundments source category is only an approximation because this source '
category was specifically designed for traditional surface impoundments such as lagoons
and ponds. Although storm water drainage wells technically are Class V injection wells,
the Surface Impoundments source category comes the closest to modeling the risks posed
by this type of Class V well.
• If your sources include abandoned oil and gas wells, you may want to consider using the
following publication for a more detailed assessment of these sources: U.S.
Environmental Protection Agency, Underground Injection Control Branch, Office of
Water and Drinking Water, Revised Risk Assessment for Abandoned Oil and Gas Wells
forthcoming, 1992.
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USER'S GUIDE 27
Write the source category'ancl name of each source on Block I of the Master Scoresheet in
Chapters.
The Master Scoresheet provides space for you to evaluate risks for up to three
contaminants or contaminant mixtures per source. If you think you will need to evaluate
more contaminants or contaminant mixtures for a given source, skip as many groups of
three rows as you will need in the Master Scoresheet now.
Number your sources in sequence in the first column of the Master Scoresheet. Use this
number to identify each source as you proceed.
Step 5 Guidance: Characterize Potential Contaminants
»• In Chapter 4, you will find one blank Source Datasheet/Worksheet pair for each source
category. Photocopy the appropriate pair of sheets for each source or group of sources
within your WHPA(s). For example, if you have two hazardous landfills and one sanitary
landfill in your WHPA, you will need to make three copies of the Landfills Datasheet and
three copies of the Landfills Worksheet.
»> At the top of each Source Datasheet, record the Source Number, Source Name, and
Source Location. Use the same Source Number and Source Name as in Block I of the
Master Scoresheet.
»• For each source listed in Block I of the Master Scoresheet, you will need to specify the
following on each Source Datasheet:
— source age and design parameters
— distance from the well
— contaminants or contaminant mixtures present. .
»• Each Source Datasheet has; a question that asks you: "Does the source discharge directly
to a conduit system (e.g., pipes or utility chase) that could transport contaminants directly
to the well?" The concern here is that a conduit (e.g., a gravel-filled trench that carries a
water main) could convey contaminants from a source to the well. To convey
contaminants, the conduit must run between a potential source of contamination and the
well, and thus provide a shortcut for contaminants around the unsaturated and saturated
zones. If the source does discharge directly to a conduit system that could transport
contaminants, then the Transport Worksheet (Task IV) will guide you to set the Likelihood
that contaminants will reach the well to 0 (i.e., a 100 percent chance of reaching the well).
»• For some parameters, the datasheets provide default values. While site-specific data are
always preferred, you may use the default values if specific information is not readily
available. For more details on the use of defaults, please refer to the "Using Defaults"
discussion earlier in this chapter.
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USER'S GUIDE
28
Choose up to three contaminants or contaminant mixtures associated with the source and
list them in the Contaminant Data Table of the Source Datasheet. If you choose more than
three contaminants, you can write the additional contaminant names and corresponding
scores in the available space on the source datasheets and worksheets. You will need to
use Contaminant Forms S.I and/or S.2 in Chapter 3 to complete the Contaminant Data
Table.
— If you know the contaminants present at the source and the concentration of each
contaminant, then
(1) use Form S.I to obtain the persistence, mobility, and toxicity of those
contaminants,, and -- =
(2) convert the concentration value (in ppm or mg/1) into a concentration score
using the Contaminant Concentration Scoring Graph that follows Form S.I.
For Agrichemical Application sources, use the application rate in kg/hectare/yr
instead of concentration.
- If you do not know the contaminants present at the source or their concentrations,
then use Form S.2 to identify characteristic contaminants and to obtain default scores
for persistence, mobility, toxicity, and concentration by source category and
subcategory.
For more information on how to use Forms S.I, S.2, and the Contaminant Concentration
Scoring Graph, see the introduction to Contaminant Forms S.I and S.2 in Chapter 3.
If you group sources, you will complete one datasheet/worksheet pair for each group of
sources. For a block of homes that use septic tank systems, for example, you will begin
by completing one datasheet. To do this, you will need to determine the average age of
the group of septic tank systems (step SD1), estimate the aggregate amount of sewage
throughput of all the septic tank systems (step SD2), and determine the distance range for
all the septic tank systems from the well (step SD3). Using these data from the datasheet,
you can then complete one worksheet for this group of septic tank systems. For an
illustration of how to group sources, refer to the hypothetical example in the next section.
Make a note on the contaminant data table of whether your source contains potential dense
non-aqueous phase liquids (DNAPLs) or potential light non-aqueous phase liquids
(LNAPLs), as identified in Form S.I under the column heading "Type." DNAPLs, also
known as sinkers, are contaminants with densities greater than water and are relatively
insoluble in water. LNAPLs, also known as floaters, are contaminants with densities less
than water and are relatively insoluble in water. Potential DNAPLs and LNAPLs will act
as true DNAPLs or LNAPLs if they are released in great enough quantities. The guidance
under Task III, Step 6 will help you determine whether a potential DNAPL or LNAPL
will act as a true DNAPL or LNAPL. For a more detailed discussion of Ihe special risks
posed by DNAPLs and LNAPLs, see Technical Appendix A.
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USER'S GUIDE 29
A NOTE ON NEGATIVE SCORES
Human health risk assessments are calculated by multiplying variable factors (such as
toxicity or potency of a substance and the frequency and duration of exposure) to derive
a numerical risk assessment based on the probability of an expected outcome, such as
one in one million cancer deaths from prolonged exposure to asbestos, etc.
For this Approach, the natural numbers in the scoring system have been converted to
decimal logarithms for use in the equation: Risk = Likelihood -f Severity. Thus,
when users are adding the variables in this Approach, the variables are in effect being
multiplied, as in the calculation of human health risk assessments.
As you complete the Source Datasheets and all other sheets of this manual, you
will find that many scores are negative numbers. The reason these scores are
negative is because the scoring system here is based on the decimal logarithmic
conversion of natural units. For example, if there is a 50 percent chance
contaminants will be released from a given source, then the Likelihood of Release
score for that contaminant at that source is -0.3 (logw (0.5)). Be careful to precede
all numbers with the correct sign (+ or -) as you copy scores from one sheet to
another. Also keep in mind the meaning of the sign as you compare scores; that
is, a score of (-2) is greater than a score of (-3).
Task III: Perform Source Calculations
Steps* Name and Location of
• • - -'....=•••• Data Entry Sheets
6. Using data from the Wellhead and Source Datasheets, Source Worksheet (Chap. 4)
assess contaminants released from the source
7. Transfer scores Lt> <& and; T to the Master Scoresheet Block H of the Master
• - ' Scoresheet (Chap. 3)
Step 6 Guidance: Assess Contaminants Released from the Source
*• In Chapter 4, you will find one blank Source Datasheet/Worksheet pair for each source
category. If you have not done so already, photocopy as many copies of the appropriate
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USER'S GUIDE
30
Source Worksheets as there are corresponding sources or groups of sources within your
WHPA(s).
> For each source, work through all of the steps in the corresponding Source Worksheet
found in Chapter 4. You will be estimating two source-related elements of risk:
— Lt Likelihood of Release at the Source
— Q Quantity Released at the Source
In order to complete the steps in the Source Worksheet, you will need to look up data in
the corresponding Source Datasheet and in some cases, the Wellhead Datasheet (Chapter
•3). . ' - - - -
*• Each source will have only one Lt score because LI does not depend on the contaminant or
contaminant mixture analyzed. However, there will be one O score for each contaminant
or contaminant mixture at the source.
>• If the Quantity score for a potential DNAPL or LNAPL (identified under the guidance for
Task II, Step 5 and on Contaminant Form S.I) is greater than or equal to 3, then the .- •
contaminant is a true DNAPL or LNAPL. In this case, this Approach may overestimate
or underestimate the risks posed by that contaminant. For a more detailed discussion of
DNAPLs and LNAPLs, see Technical Appendix A.
Step 7 Guidance: Transfer Scores to Master Scoresheet
»• Copy the L! and Q scores from the Source Worksheet, and the Toxicity scores (T) from
the corresponding Source Datasheet, onto Block II of the Master Scoresheet (Chapter 3).
Task IV: Perform Transport Calculations
Steps
Name and Location of
Data Entry Sheets
8. Using data from the Wellhead and Source
Datasheets, assess contaminant transport
9. Transfer the L? and A scores to the Master
Scoresheet
Transport Worksheet (Chap. 4)
Block II of the Master
Scoresheet (Chap. 3)
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USER'S GUIDE ___ 31
Step 8 Guidance: Assess Contaminant Transport
* Photocopy one Transport Worksheet for each source within your WHPA(s).
+ You will estimate two transport-related elements of risk for each contaminant or
contaminant mixture:
LZ Likelihood of Reaching the Well
A Attenuation Due to Transport.
You will need to use data from the Wellhead Datasheet (Chapter 3) and the corresponding
Source Datasheet (Chapter 4) to complete this step.
Step 9 Guidance: Transfer Scores to Master Scoresheet
» rnpy thft T- and A scores for each contaminant or contaminant mixture to Block II of the
Master Scoresheet (Chapter 3).
TaskV: Estimate Risks and Rank Sources
Steps Name and Location of
Data Entry Sheets
10. Determine contaminant-specific L, S, and Risk Block IH of Master Scoresheet
Scores (Chap. 3)
11. Determine source-specific Risk, Rank, and Risk Block HI of Master Scoresheet
Level (Chap. 3)
12. Plot each source on the Risk Matrix Risk Matrix (Chap. 3)
Step 10 Guidance: Determine Contaminant-Specific Risk Scores
»> Working directly from the Master Scoresheet, determine the Likelihood of Well
Contamination (L) and Severity of Well Contamination (S) scores for each contaminant or
contaminant mixture at each source as follows:
L = L, + LZ
S =Q + A +.T- . .
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USER'S GUIDE 32
> Compute the Risk Score for each contaminant or contaminant mixture at each source as the
sum of the Likelihood of Well Contamination (L) and the Severity of Well Contamination
(S):
Risk score = L + S
— For example, if a contaminant or contaminant mixture has a Likelihood of Well
Contamination (L) of-1.5 and a Severity of Well Contamination (S) of 0.5, then this
contaminant or contaminant mixture has a Risk score of -1 (i.e., -1.5 + 0.5).
+ The Priority Setting Approach may overestimate or underestimate the risks posed by true
DNAPLs or LNAPLs (see Task III, Step £ for guidance on identifying DNAPLs and
LNAPLs). Because of the complexity of the transport phenomena involved, this Approach
does not provide guidance on whether the risk scores will be overestimated or
underestimated in the case of DNAPLs or LNAPLs. Therefore, this Approach may not be
applied for potential DNAPLs or LNAPLs with a Quantity score of 3 or more. For a
more detailed discussion of DNAPLs and LNAPLs, see Technical Appendix A.
>• Note that the L+S formula assumes that you place equal weights, on the Likelihood and
Severity of Well Contamination posed by a given contaminant or contaminant mixture. If
you value one of these risk factors more than the other, you may want to determine the
Risk score differently (see the discussion on "Using the Risk Matrix" at ihe end of this
task). The Risk score always increases as either Likelihood or Severity of Well
Contamination increases, as long as the other score does not decrease.
* This Approach equates a 10"5 lifetime cancer risk to a lifetime exposure to the reference
dose (RfD) for non-carcinogens. You can alter this assumption to reflect different
policies. For more discussion on how to do this, see Technical Appendix A.
Step 11 Guidance: Determine Source-Specific Overall Risk Scores
> At this point, you may choose to track carcinogenic risks and non-carcinogenic risks either
together or separately. You can determine whether a contaminant is a carcinogen or a
non-carcinogen from Contaminant Forms S. 1 and S.2 (Chapter 3). If you distinguish
between these risks, you will end up with two separate source rankings: one ranking for
carcinogenic risks and one ranking for non-carcinogenic risks. When deciding whether to
distinguish between carcinogenic and non-carcinogenic risks, it may be helpful to consider
the end use of your results. For an explanation of the difference between these two types
of risk and the assumptions built into this Approach for comparing them, refer to
Technical Appendix A.
If you choose not to distinguish between carcinogenic and non-carcinogenic risks:
>• Determine the Overall Risk score for each source by selecting the maximum contaminant-
specific Risk score obtained in Step 10.
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USER'S GUIDE 33
— For example, if a given source has three contaminants or contaminant mixtures with
Risk scores equal to -2013, -2.1, and -0.5, then this source has an Overall Risk score
equal to -0.5 (i.e., the maximum of-200, -2.1, and -0.5).
Write the Overall Risk for each source in the corresponding column of Block III of the
Master Scoresheet. Note mat the higher the Overall Risk score, the higher the risk to the
well posed by a given source.
Rank your sources on the basis of the Overall Risk scores, giving the source with the
highest Overall Risk score a Rank of 1.
— For example, if your WHPA has two sources A and B with Overall Risk scores equal. -
to -2.5 and -0.7, respectively, then source B poses a greater risk to the well than
source A. Therefore, source B would be assigned a Rank of 1 and source A a Rank of
2.
Write the Rank for each source in the Rank column of the Master Scoresheet (Block III).
Based on the Overall Risk Scores, determine the Risk Level (i.e., Low, Medium, or High)
for each source using the following table:
Overall Risk Risk Level
Less than -4 Low
Between -4 and 0, inclusive Medium
Greater than 0 High
— For example, if a given s6urce has an Overall Risk score equal to -6, then this source
poses a Low risk of well contamination. Alternatively, a source with an Overall Risk
score of 0.5 is a High risk source.
Write the Risk Level for each source in the last column of Block III of the Master
Scoresheet.
If you choose to track carcinogenic and non-carcinogenic risks separately:
Determine a Carcinogenic Overall Risk score and a Non-Carcinogenic Overall Risk score
for each source. The Carcinogenic Overall Risk score is the maximum of the
contaminant-specific Risk scores for all carcinogens at the source. Likewise, the Non-
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USER'S GUIDE 34
Carcinogenic Overall Risk score is the maximum of all non-carcinogenic contaminant-
specific Risk scores.
You will generate two rankings of all sources: one ranking based on the Carcinogenic
Risk scores and one ranking based on the Non-Carcinogenic Risk scores. You will also
determine two Risk Levels for each source: one Carcinogenic Risk Level and one Non-
Carcinogenic Risk Level.
Step 12 Guidance: Plot Each Source on the Risk Matrix
+ Photocopy one Risk Matrix (Chapter 3) for each WHPA for which you will apply the
Priority Setting Approach.
»• Plot each source on the Risk Matrix based on the Likelihood of Well Contamination (L)
and Severity of Well Contamination (S) scores for the contaminant or contaminant mixture
with the highest Risk score. The Risk Matrix allows you to visualize the relationship
between these two components of risk by the most "problematic" contaminant or
contaminant mixture present at the source.
* The Likelihood of Well Contamination (L) is on the vertical axis and varies from -7 to 0.
Note that a Likelihood (L) score of 0 corresponds to the log to the base 10 of a probability
of well contamination of 1, i.e., a 100 percent likelihood of contamination. If the L score
is less than -7 (e.g., -8), then plot that source in the * "row" of the Risk Matrix, meaning
that there is a negligible likelihood of well contamination.
> The Severity of Well Contamination (S) is on the horizontal axis and varies from -5 to +5.
For carcinogens, a Severity (S) score of 0 corresponds very roughly to an individual
lifetime risk of 10"5. For non-carcinogens, a Severity score of 0 corresponds very roughly
to an exposure dose equal to the Reference Dose. For a more detailed discussion of these
scores, refer to Technical Appendix A. If the S score is less than -5 (e.g:, -6), then plot
that source in the * "column" of the Risk Matrix, meaning the severity of contamination is
negligible.
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USER'S GUIDE
35
Using the Risk Matrix: An Example
To illustrate the final risk calculations and the use of the Risk Matrix, assume a WHPA
with only two sources: A and B. Source A has one contaminant (nitrates), while source B has
two contaminants (chloroform 2nd 1,1,1-trichloroethane). A complete application of this
Priority Setting Approach for these two hypothetical sources is provided in the next section.
Assume the following risk scores:
Source
'A
B
Contaminant/Mixture
Nitrates
Chloroform
1,1,1 -trichloroethane
L
0
-2.3
-2.4
S
-1.8
-0.3
0
Risk
-1.8
-2.6
-2.4
Overall
Risk
-1.8
-2.4
Rank
• " • 1
2
Risk Level
Medium
Medium
As explained under the guidance for Step 10, the Risk score for each contaminant or
contaminant mixture is the sum of L and S; hence the contaminant-specific Risk scores in the
table above. Following the Step 11 Guidance, the Overall Risk score for each source is the
maximum of all contaminant-specific Risk scores (if one does not distinguish between
carcinogens and non-carcinogens). Thus, source A has an Overall Risk score of -1.8 and
source B an Overall Risk score of -2.4. Based on the Overall Risk scores of sources A and B,
source A gets a Rank of 1 (i.e., it poses the highest relative risk of contaminating the well),
while source B gets a Rank of 2 (-2.4 is less than -1.8). Both sources, however, pose a
Medium Risk Level (both-1.8 and-2.4 are between-4 and 0).
Now plot sources A and B on the Risk Matrix (Step 12). As illustrated in Exhibit 6,
source B is plotted based on the L and S scores for 1,1,1-trichloroethane, the contaminant or.
contaminant mixture with the highest Risk score (-2.4 for 1,1,1-trichloroethane versus -2.6 for
chloroform). The plot for source A uses the L and S values for nitrates, the only contaminant
analyzed. Note the following:
(1) The Overall Risk score for source A (-1.8) is greater than the Overall Risk
score for source B (-2.4) because you have given equal weight to the
Likelihood and Severity of well contamination.
(2) Although source A has a greater Likelihood of contaminating the well than
source B, source A has a smaller potential Severity of well contamination.
Therefore, if you are more concerned with the Severity than the Likelihood of
well contamination, then you may give greater weight to Severity and rank
source B as a greater risk than source A.
-------
Exhibit 6
Risk Matrix - Hypothetical Example
SEVERITY OF WELL CONTAMINATION, S
i i i
o
I
1
8
ft
I
-------
USER'S GUIDE 37
For Modified Use of this Approach
»• If you do weigh Likelihood and Severity unequally, you may want to ignore the L+S
formula in the Step 10 guidance and instead determine the contaminant-specific Risk
scores by plotting each contaminant or contaminant mixture at each source on the Risk
Matrix. This will provide a more detailed picture of the Likelihood and Severity
components of the risk from the source, rather than a picture based on a single "worst-
case" contaminant or contaminant mixture. However, no "formula" is provided here for
aggregating the separate risks from these contaminants.
*• You may also wish to draw your own shaded areas on the Risk Matrix for different risk
levels that reflect your own value judgments on. the management of risks posed by
different combinations of Likelihood and Severity (e.g., by enlarging the high-risk area
and decreasing the low-risk area).
+ The type of situation where you might most want to consider giving a greater weight to
Severity is in the case of a source that has a very high Severity score, but a low Likelihood
score. For example, a massive tank rupture or a highly toxic release very close to the •
water supply would pose a high Severity of contaminating a well, but the Likelihood of
this happening may be low. This is in contrast to events that are very likely to occur, but
have a low Severity associated with them, such as low-level nitrate contamination from
low-density septic systems. On the other hand, you may believe that it is not worth
expending limited resources on high-Severity but low-Likelihood events and, therefore,
you may place less weight on Severity.
These are two of the many value judgments that you as a manager should consider in your
final site rankings and prioritization. However, these value judgments and risk
management choices involve issues that are beyond the scope of this User's Guide.
-------
-------
USER'S GUIDE 39
HYPOTHETICAL EXAMPLE OF USING THE PRIORITY SETTING APPROACH
This section presents a hypothetical example of how to use this Approach. It begins with a
brief scenario to set the stage for the example, and then presents a hypothetical application of
this Approach for each of the Approach's tasks and steps. The completed sheets for each task
are presented at the end of this section.
The Scenario
Ms. Amy Prudent, manager for the city of Anypolis, Tennessee WHPA, has just identified
a number of potential sources of contamination within the city's WHPA. To determine her
source management priorities, she decided to use this manual to help rank and screen these
sources. This example focuses on how Ms. Prudent applies this Priority Setting Approach to
two sources: a group of septic systems and an underground storage tank.
Exhibit 7 presents the flow diagram for the tasks Ms. Prudent performs. Ms. Prudent will
complete one Wellhead Datasheet, the Source Datasheet and Worksheet for Septic Tank
Systems, the Source Datasheet and Worksheet for Tanks, and two Transport Worksheets (one
for each source). As she completes these datasheets and worksheets, she transfers data to the
first two blocks in Master Scoresheet. Finally, she will complete the third and last block of the
Master Scoresheet and plot the two sources on the Risk Matrix.
Task I: Characterize Your WHPA
Steps Name and Location of
Data Entry Sheets
1. Map WHPA boundaries
2. Characterize WHPA hydrogeology Wellhead Datasheet (Chap. 3)
Step 1: Map WHPA Boundaries
Ms. Prudent identifies the boundaries of the WHPA with assistance from the following
guidance document: U.S. Environmental Protection Agency, Office of Ground-Water
Protection, Guidelines for Delineation of Wellhead Protection Areas, Washington, D.C., 1987.
-------
Exhibit?
Flow Diagram for the Hypothetical Example
Wellhead
Datasheet
Septic
System
Datasheet
tanks
Datasheet
Septic
System
Worksheet
Transport
Worksheet
for Septic
System
Master Scoresheet
Tanks
Worksheet
Transport
-^Worksheet
for Tanks
Risk
Matrix
-------
USER'S GUIDE 41
Step 2: Characterize WHPA Hydrogeology
Using local soils maps, available well logs, and other data, Ms. Prudent determines that
the WHPA has the following hydrogeologic characteristics and enters them on the Wellhead
Datasheet:
»• the depth to the aquifer is 35 feet
»• the aquifer thickness is 10 feet
»• The net infiltration is 20 inches
>• the unsaturated zone hydraulic conductivity is between 10~5 and
10"4 centimeters per second
> the saturated zone material is sand
»• the pumping rate is approximately 48 million gallons per day.
In addition, Ms. Prudent is concerned about potential contamination within the wellfield
for several generations into the future. Therefore, she enters 150 years for the Planning Period
in parameter WD1 on the Wellhead Datasheet. Based on all of this information, Ms. Prudent
completes the Wellhead Datasheet as presented at the end of this section (see Completed Sheets
from Task I: Wellhead Datasheet).
Task II: Identify and Characterize Potential Sources of Well Contamination
Steps Name and Location of
Data Entry Sheets
3. Identify and locate all sources
4. Identify and list all sources by source category and Block I of the Master
name Scoresheet (Chap. 3)
5. Characterize potential contaminants Source Datasheet (Chap. 4)
-------
USER'S GUIDE
Step 3: Identify and Locate All Sources
After conducting a comprehensive survey of current land uses within the WHPA, Ms. .
Prudent identifies the following activities as potential sources of contamination:
> 165 houses, 70 apartment units, and 25 small businesses that use septic systems
+ one underground hazardous waste storage tank at Widgets-R-Us Inc.
Step 4: List Sources by Category and Name
.Using Exhibit 5, Ms. Prudent identifies the Source Categories .she will use to characterize-
the sources and completes Block I of the Master Scoresheet For the septic systems and the
hazardous waste underground storage tank, Ms. Prudent uses the Septic Tank Systems and
Tanks source categories, respectively.
Because the septic systems are all located within the same distance range to the well, as
defined by the Distance Scoring Form in the Septic Tank Systems Datasheet, Ms. Prudent
groups these septic systems into a single source.
Step 5: Characterize Sources
Ms. Prudent completes the Septic Tank Systems Datasheet using the following data on the
group of septic systems:
> The average age of the septic systems is approximately 30 years.
»• The throughput is 40,191 thousand gallons per year.
+ The houses, apartments, and small businesses are all between
one-eighth and one-quarter of a mile from the wellhead.
> No underground conduit system extends between the septic tanks
and the well.
> Ms. Prudent does not know what contaminants the septic systems release, so she
uses Contaminant Form S.2 (Chapter 3) to complete the Contaminant Data Table
in the datasheet. According to Form S.2, the contaminant associated with septic
systems is nitrates. The form provides default values for toxicity, mobility and
persistence for this contaminant.
At this point, Ms. Prudent turns to the Tanks Datasheet and begins completing it.
Alternately, she could have proceeded to Task III to complete the Septic Tank Systems
Worksheet. If she had chosen to proceed to Task III, she ultimately would have had to return
-------
USER'S GUIDE
43
to Task II to complete the Tanks Datasheet. Ms. Prudent completes the Tank Datasheet using
the following data:
»> The tank has a capacity of 25,000 gallons.
>• It is a below-ground, fiber-reinforced plastic tank.
ft- The tank is one-year old.
>• The tank is approximately 2,000 feet from the wellhead
>• No underground conduit system extends between the tank and the well.
>• After talking to the manager of the Widgets-R-Us, Ms. Prudent learns
that the tank contains the contaminants chloroform, at a concentration of
10,000 mg/1, and 1,1,1-tri.chloroethane, at a concentration of 35,000 .
mg/1.
Ms. Prudent uses Contaminant Form S.I (Chapter 3) to enter the Toxicity, Mobility, and
Persistence scores for chlorofonn and 1,1,1-trichloroethane onto the Contaminant Data Table in
the datasheet. To determine the Concentration score for these contaminants, she uses the
Contaminant Concentration Scoring Graph provided at the end of Contaminant Form S.I
(Chapter 3). At concentrations of 10,000 mg/l and 35,000 mg/1, the Concentration scores for
chloroform and 1,1,1-trichloroemane are 1.0 and 1.5, respectively.
Task III: Perform Source Calculations
Steps
Name and Location of
Data Entry Sheets
6. Using data from the Wellhead and Source Datasheets,
assess contaminant releases from the source
7. Transfer Lj.Q, and T scores to the Master Scoresheet
Source Worksheets (Chap. 4)
Block II of the Master
Scoresheet (Chap. 3)
-------
USER'S GUIDE
44
Step 6: Assess Contaminant Releases from the Source
Ms. Prudent completes the Septic Tank Systems Worksheet using data from the Septic
Tanks Systems Datasheet. Note that the Likelihood of Release (L,) score is equal to zero
(which is equivalent to a likelihood of 100 percent) because septic systems are designed to
release to the unsaturated and saturated zones. Ms. Prudent then completes the Tanks
Worksheet using data from the Tanks Datasheet.
Step?: Transfer Scores to the Master Scoresheet
Ms. Prudent transfers the following scores onto Block II of the Master Scoresheet: the
Toxicity (T) score from step SD5 in the Septic Tank Systems Datasheet and the Likelihood of
Release (L,) and Quantity (Q) scores from steps 1 and 3, respectively, in the Septic Tank
Systems Worksheet. Likewise, she transfers the T, Lt, and Q scores from the Tanks Datasheet
and Worksheet onto Block II of the Master Scoresheet for each contaminant.
Task IV: Perform Transport Calculations
Steps
Name and Location of
Data Entry Sheets
8. Using data from the Wellhead and Source
Datasheets, assess contaminant transport
9. Transfer the LZ and A scores to the Master
Scoresheet
Transport Worksheets (Chap. 4)
Block II of the Master Scoresheet
(Chap. 3)
Step 8: Assess Contaminant Transport
Ms. Prudent completes the Transport Worksheet for the septic systems using data from the
Wellhead Datasheet and th£.Septic Tank Systems Datasheet. Likewise, she completes a
Transport Worksheet for the underground storage tank using data from the Wellhead Datasheet
and the Tanks Datasheet.
Step
-------
USER'S GUIDE 45
for each contaminant, she transfers the 1^ and A scores from the Transport Worksheet for the
tank onto Block II of the Master Scoresheet.
Task V: Estimate Risks and Rank Sources
Steps Name and Location of
Data Entry Sheets
10. Determine contaminant-specific L, S, and Risk Block III of Master Scoresheet
Scores (Chap. 3)
11. Determine source-specific Risk, Rank, and Risk Block HI of Master Scoresheet
Level (Chap. 3)
12. Plot each source on the Risk Matrix Risk Matrix (Chap. 3)
Step 10: Determine Contaminant-Specific Risk Scores
Next, Ms. Prudent determines the Likelihood of Well Contamination (L), the Severity of
Well Contamination (S), and the Risk score for the septic systems using the following formulas:
' L = L, + La
S = Q + A + T
Risk score = L + S.
-4
She enters the L, S, and Risk scores for the septic systems onto Block III of the Master
Scoresheet. Likewise, she enters the L, S, and Risk scores for each contaminant present at the
underground storage tank onto Block III of the Master Scoresheet. For the purposes of this
example, Ms. Prudent recognizes and accepts the equal weight that this Approach places on L
and S based on the formula for determining the Risk score.
Step 11: Determine Source-Specific Overall Risk Scores.
Ms. Prudent determines the Overall Risk score for each source as the highest contaminant-
specific Risk score present at each source. Because nitrate is the only contaminant of concern
for the septic systems, the Overall Risk score for this source is the Risk score for nitrates, or
-O. Ms. Prudent chooses not to distinguish between the carcinogenic and non-carcinogenic
risks presented by the underground storage tank. Therefore, she determines the Overall Risk
-------
USER'S GUIDE 46
for the tank as the maximum between the Risk score for chloroform (i.e., -2.6) and the Risk
score for 1,1,1-trichloroethane (U., -2.4). Because -2.4 is greater than -2.6, Ms. Prudent
determines that the Overall Risk score for the underground storage tank is -2.4. She enters
these scores in the "Overall Risk" column of Block III of the Master Scoresheet.
Ms. Prudent ranks the sources on the basis of the Overall Risk scores, where the source
with the higher Overall Risk score is assigned a higher rank. Ms. Prudent ranks the septic
systems first (i.e., it poses a relatively greater risk of contaminating the well) and she ranks the
underground storage tank second because the Overall Risk score for the septic systems (-1.8) is
higher than the Overall Risk score for the underground storage tank (-2.4). She enters these
scores in the "Rank" column of the Master Scoresheet.
Ms. Prudent then assigns the septic systems a Risk Level based its Overall Risk score.
Likewise, she assigns the underground storage tank a Risk Level based on its Overall Risk
score. The Risk Level for both sources is Medium. She then enters these scores in the "Risk
Level" column of the Master Scoresheet.
Step 12: Plot Each Source on Risk Matrix
Finally, Ms. Prudent plots the septic system on the Risk Matrix based on its L score (i.e.,
0) and its S score (i.e., -1.8). For the underground storage tank, she plots the risk scores for
the contaminant with the highest Risk score (i.e., 1,1,1-trichloroethane). Therefore, for the
underground storage tank she plots its L score as -2.4 and its S score as 0. Ms. Prudent sees
that she plotted both sources in the Medium risk range, which corresponds to each source's
Risk Level.
(In this case, had Ms. Prudent chosen to differentiate between the carcinogenic and non-
carcinogenic risks, it would not have changed the overall ranking of the sources or their
position in the matrix. If the overall ranking had changed, Ms. Prudent would have had to
incorporate this additional consideration into her decision making process.)
The interpretation of the risk matrix is largely up to the user. Please refer to the
discussion on the risk matrix in this chapter for a more thorough discussion of the different
ways to interpret the matrix.
-------
47
COMPLETED SHEETS FROM TASK I:
WELLHEAD DATASHEET
-------
48
Step 2
WELLHEAD DATASHEET
Author: R.
Date:
PARAMETER
INSTRUCTIONS
SCORE
WD1 Planning Period
WD2 Depth to Aquifer
Score
WD3 Aquifer Thickness
Score
WD4 Net Infiltration
Enter the number of years over which you
are concerned with the possibility of
contamination of the well. Other things
-being equal, the longer the planning
period, the higher the likelihood that
contaminants released at the source will
reach the well within the Planning Period
considered.
Use Table W.I to convert the depth to the
aquifer in the wellhead protection area
(WHPA) into a Depth to Aquifer Score. For
example, if the depth to the aquifer is
between 50 feet and 150 feet, then the
Depth to Aquifer Score is equal to 1.5.
Note: If you have a confined aquifer,
please refer to Setting 4 hi Technical
Appendix A under the heading "Aquifer
Physical Properties."
Use Table W.I to convert the thickness of
the aquifer in the WHPA into an Aquifer
Thickness Score. For example, if the
aquifer thickness is between 3.6 meters
and 1.5 meters, then the Aquifer Thickness
Score is equal to 1.0. Note that you are
using the same table for determining the
Depth to Aquifer Score and the Aquifer
Thickness Score.
Enter the annual net infiltration in inches
for the WHPA. If this is not known, use
the net infiltration map (Figure W.I) to
determine the Net Infiltration given the
geographic location of the WHPA. For example,
if the WHPA is hi New York State, then the
Net Infiltration is equal to 20.
ISO
2.0
-------
49
Table W.I
Depth to Aquifer
or Aquifer
Thickness
(m)
(ft)
Depth to Aquifer Score or
Aquifer Thickness Score
0-3.6
0-12
0.3
3.6-15
12-50
1.0
. 15-45
50-150
1.5
45-260
150-850
2.2
Table W 3
Hydraulic Conductivity
(cm/s)
Unsaturated Zone
Hydraulic Conductivity
Score
lo-9 - io-7
1
io-7-io-s
2
lo-'-io-3
3
io-3-io-1
4
io-1 - iol
5
Table W3
Unsaturated Zone
Material
Unsaturated Zone Hydraulic
Conductivity Score
Clay
1
Clayey-Silt
or Silt
2
Silty-Sand
or Sand
3
Sandy-Gravel
or Gravel
4
Karst
5
Figure W.I. Net Infiltration
(Ref.47)
-------
WELLHEAD DATASHEET (continued)
50
PARAMETER
INSTRUCTIONS
SCORE
WD5 Unsaturated Zone
Hydraulic
Score
WD6 Saturated Zone
Material
WD7 Ground-Water Velocity
Score
If you know the hydraulic conductivity of
the unsaturated zone, then use Table W.2 to
determine the Unsaturated Zone Conductivity
Score. For example, if the conductivity of
the unsaturated zone is between 10"7
centimeters/second and 10* centimeters/second,
then the Unsaturated Zone Conductivity Score
is equal to 2.
If you do not know the conductivity of the
Unsaturated zone, then use Table W.3 to
determine the Unsaturated Zone Hydraulic
Score as a function of the type of material
in the unsaturated zone. For example, if
the type of material in the unsaturated zone
is sand, then the Unsaturated Zone Hydraulic
Conductivity Score is equal to 3.
Either Silt, Sand, Gravel, or Karst as the
Saturated Zone Material. Note that the
Saturated Zone Material cannot be Clay.
If you know the average ground-water velocity
in the WHPA that takes into account the effects
of pumping, then use Table W.4 to detennine the
Ground-Water Velocity Score. For example, if
the average ground-water velocity in the WHPA
is between 10 meters/year and Iff meters/year,
then the Ground-Water Velocity Score is equal
to 3.
If you do not know the ground-water velocity in
the WHPA, then use Table W.5 to detennine the
Ground-Water Velocity Score as a function of the
type of material in the saturated zone. For example,
if the type of material in the saturated zone is
Gravel, then the Ground-Water Velocity Score is
equal to 5. Note that if the Saturated Zone
Material is Sand, then the Ground-Water Velocity
Score depends on the pumping rate at the Wellhead.
If the Saturated Zone material is Sand and the
pumping rate is less than 45 million gallons/day
-------
WELLHEAD DATASHEET (continued)
51
PARAMETER
INSTRUCTIONS
SCORE
(30,000 gallons/minute), then the Ground-Water
Velocity Score is equal to 3. If the Saturated Zone
material is Sand and the pumping rate at the wellhead
is greater than or equal to 45 million gallons/day
(30,000 gallons/minute), then the Ground-Water
Velocity Score is equal to 4.
Table W.4
Ground-
Water
Velocity
(m/yr)
(ft/yr)
Ground-Water
Velocity Score
10-1 - 101
0.3 - 3.3
2
101 - 103
3.3 x 10l -
3.3 x 103
3
103 - 10s
3.3 x 103 -
3.3 x 10s
4
10s - 107
3.3 x 10s-
3.3 xlO7
5
Table W.5
Saturated Zone
Material
Ground-Water
Velocity Score
Silt
2
Sand
3 or 4*
Gravel
5
Karst
5
3 if the wellhead pumping rate is less than 45 million gallons/day
4 if the wellhead pumping rate is greater than or equal to 45 million gallons/day
-------
-------
53
COMPLETED SHEETS FROM TASK II:
BLOCK I OF THE MASTER SCORESHEET,
SEPTIC TANKS SYSTEM DATASHEET,
AND TANKS DATASHEET
-------
Master Scoresheet
BLOCK 1
*
1
4
TASK2: IDENTFlf SOURCES
Category
SEPTIC
systems
T/WKS
Name
(rRobPof
SEITlc ^t^TC/hS
u/ll)C4TS-ft-u5
1.,, Likelihood of Release
Q- Quantity of Contaminant Released
T - Toxtdty ot Contaminant
BLOCK II
CONTAMINANT/
MIXTURE
CARCINOGEN/
NON-
CARCINOGEN
Lg > Likelihood of Reaching the Wen
A - Attenuation Due to Transport
TASK 3:
SOURCE ELEMENTS
S
Q
T
TASK 4; TRANS-
PORT ELEMENTS
S,
A
.1
L = Likelihood. L1+L2
S- Severity - Q + T + A
Rtek - L 4- S '
Overall Risk - Maximum Risk
BLOCK III
—
TASKS: ESTIMATE RISKS AND RANK SOURCES
L
S
Bisk Leva
Low
Medium
High
Risk
••- l
Overa*
Rfek
Rank
Overall RMc
Lees than -4
itwaen-4andO
3f eater than 0
Rtak
Level
i
£
!
-------
55
Source #:
SOURCE, DATASHEET - SEPTIC TANK SYSTEMS
Author:
Date:
Source Name: fifOUp tf| Sc|ptfc S
-------
SOURCE DATASHEET - SEPTIC TANK SYSTEMS (continued)
56
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD3 Distance Score
Use the table below to determine the Distance
Score as a function of the distance from the
source to the well (or to an abandoned well if
one exists between the source and the well)..
Use the shortest distance from any one unit using
3. septic system to the well. For example, if
the shortest distance between any one unit using
a septic system and the well is 1,000 feet, then
the Distance Score is equal to 2.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
0-.12
0-635
O-j.93
1
.25-.5
1320 - 2640
402 - 805
.5 -1.0
2640 - 5280
805 -1610
1.0-3.0
5280 - 15,840
1610-4829
3.0 - 5.0
15,840 - 26,400
4829 - 8040
SD4 Does the source discharge
directly to a conduit system
(e.g., pipes or utility
chase) that could transport
contaminants directly to
the well?
Yes or No
A/Q
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - SEPTIC TANK SYSTEMS (continued)
.57
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD5 Contaminant Data
Use Contaminant Forms S.I or S.2 to complete
the Contaminant Data Table below. Refer
to Task 2 of the User's Guide for additional
guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Alttratcs
Toxicity
Score
-i.5
Concentration
Score
-0.7
Mobility
Score
H
Persistence
Score
L.
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
Source #:
Source Name:
Location: O&K St .
58
SOURCE DATASHEET - TANKS Step 5
Author: n -
Date: 6/H/1f
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 "Number of Tanks
SD2 Tank Size
SD3 Tank Design
You may want to group tanks containing similar
contaminants and of similar size, design, age
and distance from the wellhead. You need
not determine the exact number of tanks;
rather, determine if the number of tanks is
within one of the following ranges: 1,2-5,
6-25, 26-75, or > 75.
Enter Small, Medium, or Large for the size of
each tank or group.
Small = < 5,000 gallons each
Medium = 5,000 - 30,000 gallons each
Large = > 30,000 gallons each
Enter the tank number using the information
in the table on the next page (Refs. 12 and 25).
Ifled.
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - TANKS (continued)
59
PARAMETER
INSTRUCTIONS*
VALUE
Tank Design
Design
Description
A. Hazardous Waste, Chemical, and Petroleum Storage Tanks
1
2
3
4
5
6
O
Above-ground bare steel tank resting on cradles on a concrete pad with curbing.
The tank capacity is less than or equal to 30,000 gallons (small or medium).
Above-ground bare steel tank resting on-grade on a concrete pad with curbing.
The tank capacity is greater than or equal to 30,000 gallons (large).
In-ground concrete tank with an open top at ground level.
Below-ground bare steel tank.
Below-ground double-walled steel tank with interstitial monitoring.
Below-ground STiP3 tank (cathodically protected).
Below-ground fiber-reinforced plastic (FRP) tank.
B. Hazardous Waste and Wastewater Treatment Tanks
8
9
10
Above-ground bare steel tank resting on cradles on a concrete pad with curbing.
The tank capacity is less than or equal to 30,000 gallons (small or medium).
Above-ground bare steel tank resting on-grade on a concrete pad with curbing.
The tank capacity is greater than or equal to 30,000 gallons (large).
In-ground concrete tank with an open top at ground level.
C. Hazardous Waste Small Quantity Generator and Farm Storage Tanks
11
12
Above-ground bare steel tank resting on cradles.
Below-ground bare steel tank.
For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - TANKS (continued)
60
PARAMETER
INSTRUCTIONS*
VA1LUE
SD4 Tank Age
HYDROGEOLOGIC SETTINGS
SD5 Distance Score
Enter the age of the tank or the average
age of the tanks hi the group.
Use the table below to determine the Distance
Score as a function of the shortest distance
from the~t$nk(s) to the well-(or to the
abandoned well if one exists between the tank(s)
and the well). For example, if the
shortest distance between the tank(s) and the
well is between 1/2 and 1 mile, then the
Distance Score is equal to 4.
±
year(s)
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
0-.12
0-635
0-193
Distance Scoring Form
.12-.25
635 - 1320
193-402
402-805
.5 - 1.0
2640-5280
805 - 1610
1.0 - 3.0
5280 -15,840
1610 - 4829
3.0 - 5.0
15,840 - 26,400
4829 - 8040
Distance Score
SD6 Does the source discharge
directly to a conduit
system (e.g., pipes or
utility chase) that could
transport contaminants
directly to the well?
Yes or No
A/Q
For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - TANKS (continued)
61
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD7 Contaminant Data
Use Contaminant Forms S.I or S.2 to complete
the Contaminant Data Table below. Refer
to Task 2 of the User's Guide for additional
guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Chloro-fbrm
iJ.i-Trichknetha
Toxicity
Score
•U
nt -0.5
Concentration
Score
1.0
1.5
Mobility
Score
H
m
Persistence
Score
W
m
For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide.
(Chapter 2).
-------
-------
63
COMPLETED SHEETS FROM TASK III:
SEPTIC TANKS SYSTEM WORKSHEET,
TANKS WORKSHEET, AND
THE FIRST PART OF BLOCK II OF THE MASTER SCORESHEET
-------
64
Step 6
SOURCE #
SOURCE WORKSHEET - SEPTIC TANK SYSTEMS
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Likelihood of Release (L,),Score
Set L, = 0.
QUANTITY (Q)
Step 2 Determine the Volume Score
Likelihood of Release (L,) Score = 0
Use the graph below to determine
the Volume Score as a fimction of
the Total Sewage Throughput (SD2)
and the Septic System Age (SD1).
Volume Score by Total Sewage Throughput and Septic System Age
•a- Age 0-20 Years
"•• Age > 20 Years
100
1000
10000
100000
Total
1000000
S«mg« Throughput (Thousand Gallom/Year)
Volume Score: S
(Ref. 26)
-------
65
SOURCE WORKSHEET » SEPTIC TANK SYSTEMS (continued)
STEP INSTRUCTIONS SCORE
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Volume Score (Step 2)
+ Concentration Score (SD5)
Contaminant or Contaminant Mixture Quantity Score (Q)
m A/if rites *J3
(2)
-------
SOURCE WORKSHEET - TANKS
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Likelihood of Release (L,) Score
Use the graphs on the next page to determine the
Likelihood of Release Score (L,) as a function
of Tank Design (SD3) and Tank Age (SD4). For
Designs 1-3, use the first graph; for Designs 4-7,
use the second graph; for Designs 8-10, use the
third graph; and for Designs 11-12, use the fourth
graph. Note that if your Tank Design is 3 or 10,
Lj = 0. If Tank Age is greater than 40 years, set
the Likelihood of Release Score to 0.
Likelihood of Release (L,) Score = "3.3
(R3f. 25)
QSAPH1:
EASE SCOAC Km ABOVE-OftOUND AND M-QAOUND STORAGE TANKS
2 4 6 • 10 12 14 13 II 20 22 24 2« 2> 30
-------
67
SOURCE WORKSHEET - TANKS (continued)
STEP
INSTRUCTIONS
SCORE
j
GRAPH2: DESIGNS 4-7
UKEUHOOO OF RELEASE SCORE FOR 1H.OW-QHOUHD STORAGE TANKS
468
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
TankAg«(Y
-------
SOURCE WORKSHEET - TANKS (continued)
68
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2 Compute the Volume Score
Use the graph below to determine
the Volume Score as a function of
the Number of Tanks (SD1), Tank Size
,-(SD2), aniTank Design (SD3).
Volume Score for Storage and Treatment Tanks
Tank
Design
1
2
3
4
5
6
7
8
9
10
11
12
1
Tint Size
S
-0.2
-
-0.7
03
-1.2
0.9
. 0.4
-1
-
-0.1
-0.7
-13
=
M
-0.1
-
-0.6
0.4
-1
1
(3
-0.8
-
-0.1
-
=
L
-
0.9
-0.4
-
-
-
0.6
-
0.2
0.1
-
==;
• Number of Tanks -' " ' ' •••••,•;•••>'• • •;..'.. . .'••.' :; .' .'•.'•
2-5
Tank Size
S
0.2
-
-0.2
0.7
-0.7
1.4
0.9
-0.5
-
0.3
-0.3
-0.9
=^=:
M
0.3
-
-0.1
0.8
-0.5
1.5
1
•0.3
-
•03
-
—
L
-
1.3
0.1
-
-
-
1.1
-
0.7
0.5
-
^==
6-25
Tank Size
S
1.4
-
1
1.9
0.5
2.6
2.1
0.7
-
1.5
0.9
0.9
M
1.5
-
1.1
2
0.7
2.7
2.2
0.9
-
1.5
-
-
L
-
2.5
1.3
-
-
-
2.3
-
1.9
1.7
-
-
26-75
S
1.9
-
1.5
2.4
1
3.1
2.6
1.2
-
2
1.4
0.8
M
2
-
1.6
2.5
1.2
3.2
2.7
1.4
-
2
-
:^==
L
-
3
1.8
-
-
-
2.8
-
2.4
2.2
-
— — —
>75
S
2.2
-
1.8
2.7
1.3
3.4
2.9
1.5
.
2.3
1.7
1.1
M
2.3
-
1.9
2.8
1.5
3.5
3
1.7.
.
2.3
.
-
L
_
3.3
2.1
_
.
.
3.1
_
2.7
2.5
.
-
- Indicates not applicable
S. = Small, M = Medium, L = Large
Volume Score: O.S
(Ref. 25)
-------
69
SOURCE WORKSHEET - TANKS (continued)
STEP INSTRUCTIONS SCORE
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration Score (SD7)
.+ Volume Score (Step 2)
Contaminant or Contaminant Mixture Quantity Score (Q)
(i) Chloroform 1.5
(2) i, i j- Tn*eh loreethane. 3.0
(3)
-------
Master Scoresheet
BLOCK 1
TASK 2: IDENTIFY SOURCES
*
1
a
Categ
-------
71
COMPLETED SHEETS FROM TASK IV:
TRANSPORT WORKSHEET FOR SEPTIC SYSTEMS,
TRANSPORT WORKSHEET FOR TANKS, AND
THE SECOND PART OF BLOCK II OF THE MASTER SCORESHEET
-------
TRANSPORT WORKSHEET
STEP INSTRUCTIONS SCORE
This worksheet* provides guidance for determining scores for each step in the transport
calculations. In this guidance, the labels in parentheses refer to three sources of scores:
>• scores from a step in the Wellhead Datasheet, e.g., (WD2)
>• scores from the Source Datasheet, i.e.,~(SD>
>• scores from a step in this Transport Worksheet, e.g., (Step 5).
Step 1 Compute Timeframe
Timeframe (years) = Age of Source (SD)
+ Planning Period (WD1)
Timeframe = ISO
CONTAMINANT-SPECIFIC STEPS
Steps 2 through 8 will help you calculate two risk elements for each contaminant or
contaminant/mixture at the source: Likelihood of Reaching the Well (L^) and Attenuation Due to
Transport (A). For a given source, Lj and A vary only with the contaminant's mobility and
persistence. Therefore, you need only recompute 1^ and A by completing Steps 2 through 8 for
contaminants with different values of mobility and/or persistence.
Step 2 Determine Hydraulic Conductivity and Velocity Scores
Use the following table to determine the Hydraulic
Conductivity and Velocity Scores as a function of
the Contaminant Mobility (SD) and either the
Unsaturated Zone Hydraulic Conductivity score
(WD5) or the Ground-Water Velocity score (WD7),
respectively. For example, if Contaminant Mobility
. is Medium and the Unsaturated Zone Hydraulic
Conductivity score is 4, then the Hydraulic
Conductivity Score is equal to 3.
References 17, 43, 57, and 73 were used to develop this worksheet.
-------
TRANSPORT WORKSHEET (continued)
73
STEP
INSTRUCTIONS
SCORE
Adjusted Hydraulic Conductivity and Velocity Scores
Unsaturated Zone
Hydraulic Conductivity
Score or Ground-Water
Velocity Score
1
2 - ' "•
5
Contaminant Mobility
L
1
1
1
2
3
M
1
1
2
3
4
ou
\~S
i
2 '
8\
5
Hydraulic Conductivity Score =
Velocity Score =
CONTAMINANT
1 23
Quick Exit
If the source discharges directly to a conduit
system that could transport contaminants directly
„ to the well (SD), then for each contaminant
. at the source:
Skip Steps 3 and 4, set the Likelihood of
Reaching the Well (Lj) in Step 5 equal to 0,
and go to Step 6.
-------
74
TRANSPORT WORKSHEET (continued)
STEP
INSTRUCTIONS
SCORE
Step 3 Determine Unsaturated Zone and Saturated Zone Time of Travel (TOT) Categories
Use the following table to determine
the Unsaturated Zone TOT Category as a
function of the Depth to Aquifer score (WD2)
and the Hydraulic Conductivity score (Step 2).
For example, if the Depth to Aquifer score is
1^5 and the Hydraulic Conductivity Score isr2,
then the Unsaturated Zone TOT Category is D.
Unsaturated Zone Time of Travel Category
Depth to
rtijuiicr
Score
0.3
©
1.5
2.2
Hydraulic Conductivity
1
E
F
F
F
2
B
C
D
D
©
A
©
B
B
Score
4
A
A
A
A
5
A
A
A
A
Unsaturated Zone TOT Category =
CONTAMINANT
1 2 3
-------
TRANSPORT WORKSHEET (continued)
75
STEP
INSTRUCTIONS
SCORE
Likewise, use the following table to determine
the Saturated Zone TOT Category as a function
of the Distance score (SD) and Velocity Score
(Step 2).
Saturated Zone Time of Travel Categories
Distance
Score
1
(D
3
4
5
6
Velocity Score
2
D
D
E
F
F
F
3
B
B
B
C
C
C
©
A
©
A
A
A
A
5
A
A
.A
A
A
A
Note: If the Velocity Score is 1, then the Saturated Zone Time of Travel
Category is Equal to F
CONTAMINANT
Saturated Zone TOT Category = n
-------
76
TRANSPORT WORKSHEET (continued)
STEP
INSTRUCTIONS
SCORE
Step 4 Determine Unsaturated Zone and Saturated Zone Ijkelihoods (Lu) and
Use the following table to find the
Unsaturated Zone Likelihood (Lu) as
a function of the Unsaturated Zone TOT
Category (Step 3) and Timeframe (Step 1).
Unsaturated and Saturated .Zone Likelihood Scores (L,, and
, Time of
Travel
Category
©
B
C
D
E
F
Timeframe (Years)
1-10
0
-0.3
-3
-100
-100
-100
11-100
0
0
-0.3
-0.9
-100
-100
101-500
©
0
-0.1
-0,3
-0.3
-100
501-1000
0
0
0
-0.1
-0.3
-100
CONTAMINANT
12 3
.Unsaturated Zone Likelihood (L^) = _Q_
Use the same table to determine the Saturated
Zone Likelihood (Ls) as a function of the
Saturated Zone TOT Category (Step 3) and
Timeframe (Step 1).
Saturated Zone Likelihood (Lj) = &
-------
77
TRANSPORT WORKSHEET (continued)
STEP INSTRUCTIONS SCORE
StepS Compute Likelihood of Reaching the Well (Li)
Set
\^ = LU (Step 4) + Ls (Step 4)
Note: As the Likelihood of Reaching the Well
(Lj) score becomes very low (i.e., less than
-10), the estimated risk approaches a negligible
value.
CONTAMINANT
1 23
Likelihood of Reaching the Well (L^) = Q
Step 6 Determine Unsaturated Zone Attenuation (Ac)
Use the following table to determine the Unsaturated
Zone Attenuation (A0) as a function of the Depth to
Aquifer score (WD2), the Hydraulic Conductivity score
(Step 2), and Contaminant Persistence (SD). For
example, if the Depth to Aquifer Score is 1.5, the
Hydraulic Conductivity score is 2, and the Contaminant
4 Persistence is High, then the Unsaturated Zone Attenuation
is equal to 0.
-------
TRANSPORT WORKSHEET (continued)
78
STEP
INSTRUCTIONS
SCORE
Unsaturated Zone Attenuation Scores
Hydraulic
Conductivity
Score
1
2
©
4
ssssrrrsss-sss—
Contaminant
Persistence
L
M
H
L
M
H
©
M
H
L
M
H
Depth to Aquifer Score
0.3
-100
-6
-0.2
-100
-0.1
0
-0.2
0
0
0
0
0
CL2/
-100
-31.2
-1.2 .
-100
-0.3
0
©
0
0
0
0
0
1.5
-100
-94.8
-3.6
-100
--0.9
0
-3.6
0
0
0
0
0
2.2
-100
-100
-12.0
-100
-3.1
-0.1
-12.0
0
0
-0.1
0
0
Note: If the Hydraulic Conductivity Score is 5, then At, is equal to 0 (regardless of the
contaminant persistence and depth to aquifer scores).
CONTAMINANT
1 23
Unsaturated Zone Attenuation (Au) = -|.
-------
79
TRANSPORT WORKSHEET (continued)
STEP INSTRUCTIONS SCORE
Step 7 Compute Saturated Zone Attenuation (As)
Use the table on the next page to determine the
Unadjusted score as a function of the Saturated
Zone Material (WD6), the Distance score (SD),
the Velocity score (Step 2), and Contaminant
Persistence (SD). For example, if the Saturated
- Zone Material is Sand, the Design score is 2, the
Velocity score is 3, and the Contaminant Persistence
is High, then the Unadjusted score is equal to -0.6.
Then set
As = Unadjusted score (from table)* 3.1 ~ 0.3 * "*•*
- Aquifer Thickness score (WD3).
You must subtract the Aquifer Thickness score from the
Unadjusted score to determine AS.
CONTAMINANT
123
Saturated Zone Attenuation (As) = *3tH _ _ \_
Step 8 Compute Attenuation Due to Transport (A)
Set
-1.3 * -3.1 * ~H.t,
A = AU (Step 6) -}- As (Step 7).
Note: Low values of the Attenuation Due to
Transport score (A) generally cause the Potential
Severity of Well Contamination to be relatively
small. For a value less than -1.0, the potential
Severity of Well Contamination
generally is negligible.
CONTAMINANT
Attenuation due to Transport (A) =
-------
Unadjusted Saturated Zone Attenuation Scores
Saturated Zone Material
CP
L
M
H
L
M
H
M
H
L
M
H
SILT
sssssss
Distance Score
1
-100 -100 -100 -100 -100 -100
-2.0 -10.0 -22.0 -45.8 -100 -100
1.8 1.3 0.7 -0.3 -3.3 -8.0
-15.1 -45.7 -91.5 -100 -100 -100
0.0 -0.3 -0.6 -1.0 -1.9 -3.3
0.0 -0.2 -0.4 -0.5 -0.8 -1.0
-2.1 -2.7 -3.3 -4.3 -7.3 -11.9
-2.0 -2.2 -2.4 -2.5 -2.7 -2.9
-2.0 -2.2 -2.4 -2.5 -2.7 -2.9
-4.0 -4.2 -4.4 -4.5 -4.8 -5.0
-4.0 -4.2 -4.4 -4.5 -4.7 -4.9
-4.0 -4.2 -4.4 -4.5 -4.7 -4.9
SAND
^-
Distance Score
1
-100 -100 -100 -100 -100 -100
-2.3 -10.2 -22.3 -46.1 -100 -100
1.6 0.9 0.4 -0.7 -3.7 -8.3
-15.4 -46.0 -91.8 -100 -100 -100
-0.3 -0.7 -0.9 -1.4 -2.3 -3.6
-0.3 -0.6 -0.7 -0.9 -1.2 -1.3
-2.3 A3Tl}-3.6 -4.7 -7.7 -12.2
-2.3 -2.6 -2.7 -2.9 -3.1 -3.2
-2.3 -2.6 -2.7 -2.9 -3.1 -3.2
-4.3 -4.5 -4.7 -4.9 -5.2 -5.3
-4.3 -4.6 -4.7 -4.9 -5.1 -5.2
-4.3 -4.6 -4.7 -4.9 -5.1 -5.2
GRAVEL
—-
Distance Score
1
-100 -100 -100 -100 -100 -100
-2.7 -10.6-22.6 -46.4-100.7100
1.2 0.6 0.0 -1.0 -4.0 -8.7
-15.7 -46.3 -92.6 -100 -100 ,-100
-0.7 -1.0 -1.3 -1.7 -2.6 'M.O
-0.7 -0.9 -1.1 -1.2 -1.5 -1.7
-2.7 -3.4 -4.0 -5.0 -8.0 -12.5
-2.7 -2.9 -3.1 -3.2 -3.4 -3.6
-2.7 -2.9 -3.1 -3.2 -3.4 • -3.6
-4.7 -4.9 -5.1 -5.2 -5.5 -5.7
-4.7 -4.9 -5.1 -5.2 -5.4 -5.6
•4.1 -4.9 -5.1 -5.2 -5.4 -5.6
KARST
—
Distance Score
1
-100 -100 -100 -100 -100 -100
-3.8 -11.9-23.9 -47.7-100 -100
0.0 -0.5 -1.1 -2.1 -8.1 -9.8 "
-1.8 -15.0-47.6 -93.4-100 -100
-1.8 -2.1 -2.4 -2.8 -3.7 -5.1
-1.8 -2.0 -2.2 -2.3 -2.6 -2.8
-3.8 -4.5 -5.1 -8.1 -891 -13.7
-3.8 -4.0 -4.2 -4.3 -4.5 -4.7
-3.8 -4.0 -4.2 -4.3 -4.5 -4.7
-5.8 -€.0 -6.2 -6.3 -6.6 -6.8
-5.8 -6.0 -6.2 -6.3 -6.5 -6.7
-5.8 -6.0 -6.2 -6.3 -6.5 -6.7
Note: VS = Velocity Score, CP = Contaminant Persistence
i
If the velocity score is 1, then the Unadjusted Saturated Zone Attenuation Score is equal to -100 (regardless of contaminant persistence, saturated
zone material and distance score). "»«"«*
-------
TRANSPORT WORKSHEET
STEP INSTRUCTIONS SCORE
This worksheet* provides guidance for determining scores for each step hi the transport
calculations. In this guidance, the labels in parentheses refer to three sources of scores:
>• scores from a step in the Wellhead Datasheet, e.g., (WD2)
> scores from the Source Datasheet, i.e., (SD) - -
>• scores from a step in this Transport Worksheet, e.g., (Step 5).
Step 1 Compute Timeframe
Timeframe (years) = Age of Source (SD)
+ Planning Period (WD1)
Timeframe = |5j
CONTAMINANT-SPECIFIC STEPS
Steps 2 through 8 will help you calculate two risk elements for each contaminant or
contaminant/mixture at the source: Likelihood of Reaching the Well (Lj) and Attenuation Due to
Transport (A). For a given source, Lj and A vary only with the contaminant's mobility and
persistence. Therefore, you need only recompute Lj and A by completing Steps 2 through 8 for
contaminants with different values of mobility and/or persistence. -
Step 2 Determine Hydraulic Conductivity and Velocity Scores
Use the following table to determine the Hydraulic
Conductivity and Velocity Scores as a function of
the Contaminant Mobility (SD) and either the
Unsaturated Zone Hydraulic Conductivity score
(WD5) or the Ground-Water Velocity score (WD7),
respectively. For example, if Contaminant Mobility
is Medium and the Unsaturated Zone Hydraulic
Conductivity score is 4, then the Hydraulic
Conductivity Score is equal to 3.
References 17, 43, 57, and 73 were used to develop this worksheet.
-------
-------
TRANSPORT WORKSHEET (continued)
82
STEP
INSTRUCTIONS
SCORE
Adjusted Hydraulic Conductivity and Velocity Scores
Unsaturated Zone
Hydraulic Conductivity
Score or Ground-Water
Velocity Score
1
2 :
5
Contaminant Mobility
L
1
1
1
2
3
1
1
2"
3"
4
H
1
2
3>
4/
5
Hydraulic Conductivity Score =
Velocity Score =
CONTAMINANT
1 23
Quick Exit
If the source discharges directly to a conduit
system that could transport contaminants directly
to the well (SD), then for each contaminant
at the source:
Skip Steps 3 and 4, set the Likelihood of
Reaching the Well (Lj) in Step 5 equal to 0,
and go to Step 6.
-------
83
TRANSPORT WORKSHEET (continued)
STEP
INSTRUCTIONS
SCORE
Step 3 Determine Unsaturated Zone and Saturated Zone Time of Travel (TOT) Categories
Use the following table to determine
the Unsaturated Zone TOT Category as a
function of the Depth to Aquifer score (WD2)
and the Hydraulic Conductivity score (Step 2).
For example, if the Depth to Aquifer score is
-1.5 and the-Hydraulic Conductivity Score is 2,
then the Unsaturated Zone TOT Category is D. "~
Unsaturated Zone Time of Travel Category
Depth to
Aquifer
Score
0.3
©
1.5
2.2
Hydraulic Conductivity
1
E
F
F
F
B
c'l
D
D
.
A
A/
B
B
Score
4
A
A
A
A
5
A
A
A
A
Unsaturated Zone TOT Category =
CONTAMINANT
1 23
«__£
-------
TRANSPORT WORKSHEET (continued)
STEP
INSTRUCTIONS
SCORE
Likewise, use the following table to determine
the Saturated Zone TOT Category as a function
of the Distance score (SD) and Velocity Score
(Step 2).
Saturated Zone Time of Travel Categories
Distance
Score
1
2
(D
4
5
6
Velocity Score
2
D
D
E
F
F
F
(D
B
B
B//
C
. C
C
©
A
A
A/
A
A
A
5
A
A
A
A
A
A
Note: If the Velocity Score is 1, then the Saturated Zone Time of Travel
Category is Equal to F
CONTAMINANT
1 2 3
Saturated Zone TOT Category =
-------
TRANSPORT WORKSHEET (continued)
85
STEP
INSTRUCTIONS
Time of
Travel
Category
M ©S
B S
U
-------
86
TRANSPORT WORKSHEET (continued)
STEP INSTRUCTIONS SCORE
StepS Compute Likelihood of Reaching the Well
Set
L2 = Ln (Step 4) + Ls (Step 4)
Note: As the Likelihood of Reaching the Well
(L-j) score becomes very low (i.e., less than
-10), the estimated risk approaches a negligible
value.
Likelihood of Reaching the Well
Step 6 Determine Unsaturated Zone Attenuation (Av)
Use the following table to determine the Unsaturated
Zone Attenuation (An) as a function of the Depth to
Aquifer score (WD2), the Hydraulic Conductivity score
(Step 2), and Contaminant Persistence (SD). For
example, if the Depth to Aquifer Score is 1.5, the
Hydraulic Conductivity score is 2, and the Contaminant
Persistence is High, then the Unsaturated Zone Attenuation (An)
is equal to 0.
-------
TRANSPORT WORKSHEET (continued)
87
STEP
INSTRUCTIONS
SCORE
Unsaturated Zone Attenuation Scores (Av)
Hydraulic /
Conductivity
Score
1
©
©
4
Contaminant
Persistence
L
M
H
L
©
H
L
©
H
L
M
H
Depth to Aquifer Score
0.3
-100
-6
-0.2
-100
-0.1
0
-0.2
o.
0
0
0
0
©
-100
-31.2
-1.2
-100
X>.3//
0
-1.2
O/
0
0
0
0
1.5
-100
-94.8
-3.6
-100
-0.9
0
-3.6
0
0
0
0
0
2.2
-100
-100
-12.0
-100
-3.1
-0.1
-12.0
0
0
-0.1
0
0
Note: If the Hydraulic Conductivity Score is 5, then A^ is equal to 0 (regardless of the
contaminant persistence and depth to aquifer scores).
CONTAMINANT
1 23
Unsaturated Zone Attenuation (Au) = Q -0.3
-------
88
TRANSPORT WORKSHEET (continued)
STEP INSTRUCTIONS SCORE
Step 7 Compute Saturated Zone Attenuation (As)
Use the table on the next page to determine the
Unadjusted score as a function of the Saturated
Zone Material (WD6), the Distance score (SD),
the Velocity score (Step 2), and Contaminant
Persistence (SD). For example, if the Saturated
Zone Material is Sand, the Design score is 2, the
Velocity score is 3, and the Contaminant Persistence
is High, then the Unadjusted score is equal to -0.6. - "
Then set - 3.7- 0.3 s "3
As = Unadjusted score (from table) "0.^-0.3* ~ '*
- Aquifer Thickness score (WD3).
You must subtract the Aquifer Thickness score from the
Unadjusted score to determine AS.
CONTAMINANT
123
Saturated Zone Attenuation (As) = *3 "^2
Step 8 Compute Attenuation Due to Transport (A) •
Set .
•*
A = AU (Step 6) + As (Step 7).
Note: Low values of the Attenuation Due to
Transport score (A) generally cause the Potential
Severity of Well Contamination to be relatively
small. For a valueless than-1.0, the potential
Severity of Well Contamination
generally is negligible.
CONTAMINANT
1 2 3
Attenuation due to Transport (A) = ~3 "*I.S
-------
89
Unadjusted Saturated Zone Attenuation Scores
Saturated Zone Material
SILT
— —"J | •' | - •!'•' -1111 L I.J.! _.-__-!_ _ •—-—
vs
2
©
O
5
•
CP
L
M
H
L
©
H
L
(H)
H
L
M
H
==
Distance Score
1
-100
-2.0
1.8
-15.1
0.0
0.0
-2.1
-2.0
-2.0
-4.0
-4.0
-4.0
==
2
-100
3
-100
4
5
6
-100 -100 -100
-10.0 -22.0 -45.8 -100
1.3
0.7
-45.7 -91.5
-0.3
-0.2
-2.7
-2.2
-2.2
-4.2
-4.2
-4.2
-0.6
-0.4
-3.3
-2.4
-2.4
-4.4
-4.4
-4.4
-0.3
-100
-1.0
-0.5
-4.3
-2.5
-2.5
-4.5
^.5
-4.5
-3.3
-100
-1.9
-0.8
-7.3
-2.7
-2.7
-4.8
-4.7
-4.7
-100
-8.0
-100 .
-3.3
-1.0
-11.9
-2.9
-2.9
-5.0
-4.9
-4.9
(SAND)
Distance Score
1
-100
-2.3
2
3
-100 -100
-10.2 -22.3
1.6 0.9 0.4
-15.4 -46.0-91.8
-0.3 -0.7 (
0.91
*****
-0.3 -0.6 -0.7
-2.3 -3.1 -3.6
-2.3 -2.6^2/7}
-2.3 -2.6 -2.7
-4.3 -4.5 -4.7
4
-100
-46.1
-0.7
-100
-1.4
-0.9
5 1 6
-100 -100
-100 -100
-3.7 -8.3
-100 -100
-2.3 -3.6
-1.2 -1.3
-4.7 -7.7 -12.2
-2.9 -3.1 -3.2
-2.9 -3.1 -3.2
-4.9 -5.2 -5.3
-4.3 -4.6 -4.7 -4.9 -5.1 -5.2
-4.3 -4.6 -4.7 -4.9 -5.1 -5.2
GRAVEL
Distance Score
1
-100
-2.7
1.2
?.
-100
3
-100
-10.6 -22.6
0.6
-15.7 -46.3
-0.7
-0.7
-2.7
-2.7
-2.7
-4.7
-4.7
•4.7
-1.0
-0.9
-3.4
-2.9
-2.9
-4.9
-4.9
-4.9
0.0
-92.6
-1.3
-1.1
-4.0
-3.1
-3.1
-5.1
-5.1
-5.1
4
-100
-46.4
-1.0
-100
-1.7
-1.2
-5.0
-3.2
-3.2
-5.2
-5.2
-5.2
5
-100
-100
-4.6
-100
-216.
-1.5
-8.0
-3.4
-3.4
-5.5
-5.4
-5.4
6
-100
-100
-8.7
-100
-4.0
-1.7
-12.5
-3.6
-3.6
-5.7
-5.6
-5.6
KARST
Distance Score
1
-100
-3.8
0.0
-1.8
-1.8
-1.8
-3.8
-3.8
-3.8
-5.8
-5.8
-5.8
2
1
4
5
6
-100 -100 -100 -100 -100
-11.9-23.9 -47.7-100 -100
-0.5
-1.1
-2.
1 -8.
1 -9.8
-15.0 -47.6 -93.4 -100 -100
-2.1
-2.0
-4.5
-4.0
-4.0
-6.0
-6.0
-6.0
-2.4
-2.2
-5.1
-4.2
-4.2
-6.2
-6.2
-6.2
-2.8 -3.7 -5.1
-2.3 -2.6 -2.8
-8.1 -891 -13.7
-4.3 -4.5 -4.7
-4.3 -4.5 -4.7
-6.3 -6.6 -6.8
-6.3 -6.5 -6.7
-6.3 -6.5 -6.7
Note: VS = Velocity Score, CP = Contaminant Persistence
If the velocity score is 1, then the Unadjusted Saturated Zone Attenuation Score is equal to -100 (regardless of contaminant persistence, saturated
zone material and distance score).
-------
Master Scoresheet
BLOCK 1
TASK 2: IDENTIFY SOURCES
*
1
a
Category
septic
systems
-
TfllMS
Name
Gftoup OF
sefnt svsTfcmy
Iirit>ef7s-f?-u?
BLOCK II
CONTAMINANT/
MIXTURE
f/llrt^TES
ejliefiprirn
ltl,l-T4A
CARCINOGEN/
NON-
CARCINOGEN
iJori^Mutt
cnitCiiv
tfttl-ttMtoti
TASK 3:
SOURCE ELEMENTS
S
0
-33
o
4x3L
5.5
-*-
T
»l K
!•£
-*.<
TASK 4: TRANS-
PORT ELEMENTS
s.
-°-
U
.9.)
A
^^
*5
»«.5
!
BLOCK III
TASKS: ESTIMATE RISKS AND RANK SOURCES
L
S
Rbk
Overall
Risk
Rank
Risk
Level
L, - Likelihood of Release
Q - Quantity of Contaminant Released
T - Toxldty of Contaminant
L. * Likelihood of Reaching the Well
A - Attenuation Due to Transport
L-Likelihood
S- Severity - Q + T + A
RIsk-L + S
Overall Rtek - Maximum Risk
Risk Level Overall Risk
Low •• •• LeB8than-4
Medium Between -4 and 0
High :••;•• Greater than 0
CM
ff
"O
-------
91
COMPLETED SHEETS FROM TASK V:
BLOCK HI OF THE MASTER SCORESHEET
AND THE RISK MATRIX
-------
Master Scoresheet
BLOCK 1
TASK 2: IDENTIFY SOURCES
*
1
a
Category
septic
sysrems
1MB
Name
Gftottp of
vwcn-it-itf
U, , Likelihood of Release
Q - Quantity of Contaminant Released
T - Toxtelty of Contaminant
4.
BLOCK II
CONTAMINANT/
MIXTURE
l/ltltrtTtl
$Hli£oftfj(l
1 '
CARCINOGEN/
NON-
CARCINOGEN
lJO»l -CAW//Y
, _C. * "*j.fff -.,
jvtffv* £A£ff JP
TASK 3:
SOURCE ELEMENTS
L1
0
•w
Q
H3_
A5^_
T
-1.5
•0,5
TASK 4: TRANS-
PORT ELEMENTS
L2
0
•£r
A
*M«^
•3
-1.5
L. = Likelihood of Reaching the Well
A = Attenuation Due to Transport
•
L- Ukellhood «11+L2
S - Severity - Q 4 T + A
Risk - L -f S
Overall Risk - Maximum Rtsk '
BLOCK III
TASKS. ESTIMATE RISKS AND RANK SOURCES
L
J2_
^
* 3.
3
M.
S
-lift
•0.3
O
Risk
-1.8
*J.6
-M
.Overall
Risk
-1.8
•11
Rank
1
J.
Rl3H_Lev!
Low
Medium
High
>)
Overall Rjah
Less than -4
etween -4 and 0
Greater th«n 0
Rtsk
Level
*IO
m
S
I
y*
!
-------
O
8
u.
O
Q
O
O
I
Risk Matrix
SEVERITY OF WELL CONTAMINATION, S
00
I
-------
-------
95
CHAPTERS:
MASTER SCORESHEET,
WELLHEAD DATASHEET,
RISK MATRIX, AND
CONTAMINANT FORMS
-------
-------
97
MASTER SCORESHEET
-------
Master Scoresheet
BLOCK 1
TASK 2: IDENTIFY SOURCES
*
Category
Name
L, . Likelihood ol Release
Q - Quantity of Contaminant Released
I - Toxlclty ol Contaminant
BLOCK II
CONTAMINANT/
MIXTURE
CARCINOGEN/
NON-
CARCINOGEN
TASK 3:
SOURCE ELEMENTS
L1
f
•
Q
,
T
TASK 4: TRANS-
PORT ELEMENTS
L2
A
'
1
Lj = Ukelihood of Reaching the Well
A - Attenuation Due to Transport
•
L = Likelihood -^tLj
S- Severity - Q + T + A
Risk - L 4 S
Overall Risk - Maximum Risk
BLOCK III
TASKS: ESTIMATE RISKS AND RANK SOURCES
L
S
Risk
Overall
RMc
•
Rank
%
RjsK'Levi
Low
Medium
High
*
Overall Rjsk
Leas than -4
letwaan -4 and 0
Greater (dan 0
Risk
Level
-------
99
WELLHEAD DATASHEET
-------
100
Step 2
WELLHEAD DATASHEET
Author:
Date:
PARAMETER
INSTRUCTIONS
SCORE
WD1 Planning Period
WD2 Depth to Aquifer
Score
WD3 Aquifer Thickness
Score
WD4 Net Infiltration
Enter the number of years over which you
are concerned with the possibility of
contamination of the well. Other things
being equal, the longer the planning
period, the higher the likelihood that
contaminants released at the source will
reach the well within the Planning Period
considered.
Use Table W.I to convert the depth to the
aquifer in the wellhead protection area
(WHPA) into a Depth to Aquifer Score. For
example, if the depth to the aquifer is
between SO feet and ISO feet, then the
Depth to Aquifer Score is equal to 1.5.
Note: If you have a confined aquifer,
please refer to Setting 4 in Technical
Appendix A under the heading "Aquifer
Physical Properties."
Use Table W.I to convert the thickness of
the aquifer in the WHPA into an Aquifer
Thickness Score. For example, if the
aquifer thickness is between 3.6 meters
1 and 1.5 meters, then the Aquifer Thickness
Score is equal to 1.0. Note that you are
using the same table for determining the
Depth to Aquifer Score and the Aquifer
Thickness Score.
Enter the annual net infiltration hi inches
for the WHPA. If this is not known, use
the net infiltration map (Figure W.I) to
determine the Net Infiltration given the
geographic location of the WHPA. For example,
if the WHPA is in New York State, then the
Net Infiltration is equal to 20.
-------
Table W.I
101
Depth to Aquifer
or Aquifer
Thickness
(m)
(ft)
Depth to Aquifer Score or
Aquifer Thickness Score
0-3.6
0-12
0.3
3.6-15
12-50
1.0
15-15
50-150
1.5
45-260
150-850
2.2
Table W.2
Hydraulic Conductivity
(cm/s)
Unsaturated Zone
Hydraulic Conductivity
Score
10-9 - 10-7
1
io-7- io-5
2
io-3-io-3
3
io-3 - io-1
4
io-1 - io1
5
Table W J
1 Unsaturated Zone
Material
Unsaturated Zone Hydraulic
Conductivity Score
Clay
1
Clayey-Silt
or Silt
2
Silty-Sand
or Sand
3 .
Sandy-Gravel
or Gravel
4
Karst
5
Figure W.l. Net Infiltration
(Ref. 47)
-------
WELLHEAD DATASHEET (continued)
102
PARAMETER
INSTRUCTIONS
SCORE
WD5 Unsaturated Zone
Hydraulic
Score
WD6 . Saturated Zone
Material
WD7 Ground-Water Velocity
Score
If you know the hydraulic conductivity of
the unsaturated zone, then use Table W.2 to
determine the Unsaturated Zone Conductivity
Score. For example, if the conductivity of
the unsaturated zone is between 10~7
centimeters/second and 10"5 centimeters/second,
then.the Unsaturated Zone Conductivity Score
is equal to 2.
If you do not know the conductivity of the
Unsaturated zone, then use Table W3 to
determine the Unsaturated Zone Hydraulic
Score as a function of the type of material
in the unsaturated zone. For example, if
the type of material in the unsaturated zone
is sand, then the Unsaturated Zone Hydraulic
Conductivity Score is equal to 3.
Either Silt, Sand, Gravel, or Karst as the
Saturated Zone Material. Note that the
Saturated Zone Material cannot be Clay.
If you know the average ground-water velocity
in the WHPA that takes into account the effects
of pumping, then use Table W.4 to determine the
Ground-Water Velocity Score. For'example, if
the average ground-water velocity in the WHPA
is between 10 meters/year and 103 meters/year,
then the Ground-Water Velocity Score is equal
to 3.
If you do not know the ground-water velocity in
the WHPA, then use Table W.5 to determine the
Ground-Water Velocity Score as a function of the
type of material in the saturated zone. For example,
if the type of material in the saturated zone is
Gravel, then the Ground-Water Velocity Score is
equal to 5. Note that if the Saturated Zone
Material is Sand, then the Ground-Water Velocity
Score depends on the pumping rate at the Wellhead.
If the Saturated Zone material is Sand and the
pumping rate is less than 45 million gallons/day
-------
WELLHEAD DATASHEET (continued)
103
PARAMETER
INSTRUCTIONS
SCORE
(30,000 gallons/minute), then the Ground-Water
Velocity Score is equal to 3. If the Saturated Zone
material is Sand and the pumping rate at the wellhead
is greater than or equal to 45 million gallons/day
(30,000 gallons/minute), then the Ground-Water
Velocity Score is equal to 4.
Table W.4
Ground-
Water
Velocity
(m/yr)
(ft/yr)
Ground-Water
Velocity Score
10-1 - 101
0.3 - 3.3
2
101 - 103
3.3 x 101 -
3.3 x 103
3
HP-IO5
3.3 x 103 -
3.3 x 10s
4
105 - 107
3.3 x 105 -
3.3 x 107
5
Table W.5
Saturated Zone
Material
Silt
Sand
Gravel
Karst
Ground-Water
Velocity Score
3 if the wellhead pumping rate is less than 45 million gallons/day
4 if the wellhead pumping rate is greater than or equal to 45 million gallons/day
-------
-------
105
RISK MATRIX
-------
Risk Matrix
SEVERITY OF WELL CONTAMINATION, S
iii i i
z
o
o
o
111
u.
O
Q
O
O
-1
-2
-------
107
CONTAMINANT FORMS
-------
108
CONTAMINANT FORMS
USING THE CONTAMINANT FORMS
The contaminant forms (S.I and S.2) provide contaminant-specific scores necessary to
complete the contaminant data tables contained hi all of the Source Datasheets (see Chapter 2, Step
5 Guidance). These forms help you determine the Toxicity, Mobility, Persistence, and
Concentration scores for each contaminant or contaminant mixture present at a given source. You
should use Form S. 1 if you know what contaminants are present at a source and the concentration of
each contaminant. Otherwise, you need to use Form S.2, which provides default values.
Form S.I
You should use Form S.I if you already know both the contaminants present at a particular
source and the concentration of those contaminants. Form S.I contains one table and one graph.
The table provides the following information for each contaminant:
»• contaminant name
>• "type" of contaminant
»• Toxicity, Mobility, and Persistence scores
*• references for these scores.
The graph will help you determine the Concentration score for each contaminant as a function of the
contaminant's concentration at a given source.
Contaminant Name .'*.•••
Under the column titled "Contaminant," the table in Form S.I lists in alphabetical order over
60 potential ground-water contaminants. To use this table, find each contaminant present at a
source and copy its name onto the contaminant data table in the Source Datasheet. If Form S.I lists
some, but not all of the contaminants that you know are present at a given source, supplement the
information from Form S.I with default values from Form S.2. If Form S.I does not list any of the
contaminants that you know are present at a given source, then you must use Form S.2 to obtain
default values.
-------
USING THE CONTAMINANT FORMS 109
Type of Contaminant
Under the column titled "Type," the table in Form S. 1 indicates whether a particular
contaminant is (1) a carcinogen or a non-carcinogen, and (2) a potential dense non-aqueous phase
liquid (DNAPL), also known as a sinker, or a potential light non-aqueous phase liquid (LNAPL),
also known as a floater. If a contaminant is a potential DNAPL (or a potential LNAPL
respectively) and the quantity that is released annually is very high, the contaminant will behave like
a DNAPL (or LNAPL, respectively) and the final risk score may over-estimate or wider-estimate
the risk to the wellhead. This is because it is assumed here that all contaminants are dissolved in the
water, whereas DNAPLs or LNAPLs do not dissolve as readily and may migrate vertically If the
Quantity score for a potential DNAPL or LNAPL is greater than or equal to 3, then the contaminant
is a true DNAPL or LNAPL, and the Risk score for that contaminant rould be over-estimated or '-
under-estimated (see Chapter 2, Steps 5 and 6, and Technical Appendix A).
Toxicity
The Toxicity score for each contaminant is presented as a real number. Copy the
corresponding Toxicity score for each contaminant present at a given source onto the contaminant'" -
data table in the Source Datasheet.
Mobility
The Mobility score for each contaminant is presented as either an "L" for low mobility "M"
for medium mobility, or "H" for high mobility. Copy the corresponding Mobility score for 'each
contaminant present at a given source onto the contaminant data table. The Mobility score is based
on the retardation factor of each contaminant. The retardation factor is a unitless factor defined as
the ratio of the ground-water velocity to the contaminant Velocity in .the saturated zone.
Persistence
„ ^ke«±Q Mobilitv score> to6 Persistence score for each contaminant is expressed as either an
"L," "M,H or "H." Copy the corresponding Persistence score for each contaminant present at a
given source onto the contaminant data table. The Persistence score is based on the degradation rate
of each contaminant. The degradation rate is the annual exponential rate of-decomposition of the
contaminant due to chemical breakdown by bacterial action and other environmental factors
-------
USING THE CONTAMINANT FORMS 110
Contaminant Concentration Scoring Graph
The Contaminant Concentration Scoring Graph provided at the end of Form S.I allows you to
determine the Concentration score for each contaminant present at a given source. To obtain the
Concentration score for a contaminant present in any source category except Agrichemical
Application, you need to know the concentration of the contaminant at the source (in milligrams per
liter (mg/1) or parts per million (ppm); 1 mg/1 = 1 ppm). To use the Contaminant Concentration
Scoring Graph, find the concentration of the contaminant on the horizontal axis, which uses a
decimal logarithmic scale. Read up from this concentration until you hit the solid diagonal line.
Mark that point on the solid diagonal line. Next, find the Concentration score on the vertical axis
that corresponds to the point you marked on the solid diagonal line. Copy that Concentration score
onto the contaminant data table. For example, if you know the concentration, of a contaminant is.
0.3 mg/1, then the Concentration score for that contaminant is approximately -3.5.
To obtain a Concentration score for a contaminant used hi Agrichemical Applications, first
obtain the application rate of the contaminant expressed hi units of kilograms per hectare per year
(kg/hectares/yr). Then, following the instructions above but replacing kg/hectare/yr for mg/1, find
the corresponding Concentration score from the vertical axis of the scoring graph. Next add 3 to
that score to arrive at the final Concentration score. For example, if a fanner applies the pesticide
Dicamba at a rate of 40 kg/hectare/yr, then the final Concentration score for Dicamba is
approximately -1.2 + 3, or 1.8. See the hypothetical example hi Chapter 2 for another illustration
of how to use the scoring graph.
-------
USING THE CONTAMINANT FORMS
111
Form S.2
You need to use Form S.2 to complete the contaminant data table for a given source (1) if you
do not know the contaminants present at that source and their concentrations, or (2) if you know the
contaminants, but they are not listed in Form S.I. Form S.2 contains default Toxicity,
Concentration, Mobility, and Persistence scores for selected default contaminants and contaminant
mixtures for each source category. Form S.2 is organized by source categories and within each
category by different types of sources. For example, the source category for surface impoundments
(Exhibits in Chapter 2) lists different types of surface impoundments including hazardous waste
(Subtitle C) impoundments, non-hazardous waste impoundments, ponds, and lagoons.
To use Form S.-2, find the correct source-category for your source (see Chapter 2y Step 4
Guidance). The source categories are noted in the heading of each page of Form S.2; they are
arranged alphabetically, with each source category starting on a new page. Form S.2 also lists
different types of sources that fall within a given source category.
After you find the correct source category and type of source within that category, copy the
default Toxicity, Concentration, Mobility, and Persistence scores for the default contaminants listed
onto the contaminant data table in the Source Datasheet. You may decide, however, not to include
one or more of the default contaminants in the contaminant data table. For example, you may know
that a particular default contaminant listed is not present at your source; therefore, you may decide
not to list that contaminant in the contaminant data table.
To illustrate how to use Form S.2, assume you have identified the on-site waste disposal
operations at a service station within your WHPA as a potential source of contamination, but you do
not know what contaminants the station's personnel dispose. Using the guidance provided in Step 4
(Chapter 2), you determine that the appropriate source category for this source is Injection Wells:
Shallow Wells (Class V). To determine default contaminants for this source, you need to find this
source category in.Form S.2. You then read down the first column to find the most appropriate
type of source that corresponds to your source. You determine the Automobile Service Station
Disposal Wells - Service and Repair best matches your source. The default contaminants for this
source are Arsenic, Chromium, and a Metals Mix. You thus copy these contaminant names and
their corresponding default Toxicity, Concentration, Mobility, and Persistence scores onto the
contaminant data table in the Source Datasheet for that source.
-------
-------
Form S.1
i oxjciiy. Mobility and Persistence Scores by Contaminant
•...-.•*:•..• . ' . t i. it* *p' " it AJf u l i v
Contaminant
a ^— — _____
1 1,1,1-Trichloroethane
i 1,1,2,2-TetrachIoroethane
| 1 ,2-Dichlorobenzene
1 1 ,2-Trahs-Dichloroethylene
I 2,4,5-TP Silvex
2,4,6-Trichloropheno!
2,4-D
I Acetic Acid
{Acetone
| Alachior
|] Aldicarb
1 Antimony
Arsenic
—
1 Atrazine
|] Barium
1 Bentazon
| Benzene
1 Beryllium
1 Bis(2-ethylhexyl)phthalate
| Boron
1 Butylate
1 Cadmium
j — — . —
J Carbon Tetrachloride
Chloride
1 Chloroform
Type'
N, D
C, D
N, D
N, D
C
c, b
N
N
N
N
N
N
C
N
N
N
C, L
N
C, D
N
N, L
N
C, D
N
C
Toxicity
SCOT."
-0.5
2.8
-0.5
0.2
2.1
1.8
0.5
-1.5
-0.5
0.5
1.3
1.9
3.7
0.8
-0.3
1.1
2.0
0.8
1.5
-0.5
-0.3
1.7
2.5
-2.4
1.2
R«f«r«nc»*
IRIS
IRIS
HEAST
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS
HEAST
IRIS
MCL
IRIS
1
Mobility
SCOT*'
M
M
M
H "
M
M
M
H
H
M
H
L
H
M
H
M
M
M
L
M
M
M
M
H
H
R*f«r«nca*
31
31
31
31 "
47
47
37
BEJ
31
BEJ
31
31
47
31
31
BEJ
31
BEJ
31
BEJ
47
31
31
31
31
Persistence
SCOT*'
M
L
L
L
M
M
L
L
L
M
M
H
H
M
H
M
L
M
H
H
M
H
L
H
M
R«f*r«nc«*
47,27
47
47,27
27 -
66
59
37
BEJ I
BEJ I
BEJ 1L
47 ff
~^~i
47
37
47
BEJ
27
BEJ
47
47
BEJ
47
47,27
BEJ
— — — 0
27 L
-------
114
* ^ " <..-.'
Form S.1 ; /
Toxicity, Mobility and Persistence Scores by Contaminant !
Contaminant
Chromium
Cresol
Cyanazine
Cyanide
Dicamba
Dichloroethane
Dichloromethane
Dinitro-butyl phthalate
Endrin
. EPTC +
Ethylbenzene
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclopentadiene
iron
Lead
Lindane
Manganese
Mercury
Methanol
Methyl ethylketone
Methoxychlor
Metolachor
Metribuzin
M-xylene
Type'
N
N
N
N
N
C,D
C, D
N, D
N
N, L
N, L
C, D
C, D
N, D
N
N
C
N
N, D
N
N, L
N
N
M
• N, L
Toxicity
Score*
0.7
-0.2
1.2
0.2
0.0
2.4
1.3
-0.5
2.5
0.1
-0.5
3.7
2.3
0.6
0.5
1.3
3.6
-0.8
2.0
-1.2
-0.2
2.3
-0.5
0.1
-0.8
R«f«r«nc«*
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
HEAST
IRIS
IRIS
IRIS
IRIS'**
IRIS
IRIS
MCL
MCL
HEAST
HEAST
HEAST
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Mobility
SCOT*'
H
L
M
H
M
H
H
M
L
M
M
M
L
M
M
M
M
H
M
H
H
L
M
M
M
fUforanc**
31
47
BEJ
31
37
31
31
BEJ
BEJ
47
31
47
47
47
BEJ
31
47
BEJ
31
31
31
47
31
BEJ
31
Persistence
SCOT*'
H
M
M
M
L
L
L
L
M
M
L
M
L
M
H
H
L
H
H
H
L
M
M
M
L
R«f«r«nc»*
47
BEJ
BEJ
47
37
47,27
47,27
BEJ
BEJ
37
47
47,59
27
31,
47
47
47
47
47
47
27
BEJ
31
BEJ
BEJ
-------
115
• ' • •-•• •••-'•;-: -•• <• - - 1
Form S.1 "
v*sv > i, H « H, 1!
Toxlcity, Mobility and Persistence Scores by Contaminant
"* J "* j !• KI
-------
116
eVvtO NotOS'^:--^:^ ^^^^S^^&
.:'••• '. '-.J-:.:•:•••'•: ",,.'• '- ''''^ >:.':x:-K:-':' V.--''.^^1^^^^^.1':':';^'^-^;'^^:^
. •'"•' . :';' "'• ••"•'•'''• ::''.• j--- • ':::•"'' '':^:&W-^?-Y^A^-^
C = Carcinogen
N = Non Carcinogen
D = Dense Non-Aqueous Phase Liquid
L = Light Non-Aqueous Phase Liquid
Toxicity score (T) is the Logorithm of the inverse of the Critical Concentration (CC).
For carcinogens, CC is defined as the contaminant concentration in drinking water equivalent to
a 10'6 individual health risk (assuming 70 kg body weight and 2l/d average water consumption):
* 2 Id
where q* is the carcinogenic potency factor.
For non-carcinogens, the critical concentration is equal to the oral reference dose.
IRIS Integrated Risk Information System, Office of Research and Developement, U.S.
EPA. IRIS is EPA's authoritative interpretation of chemical health effects data.
HEAST Health Effects Assessment Summary Tables, ORD RD-689, April 1989. Office
of Research and Development/Office of Emergency and Remedial Response,
U.S. EPA. HEAST references are used for contaminants not listed in IRIS.
MCL Maximum Contaminant Level, National Drinking Water Standard.
Mobility score is based on the "Retardation Factor," as follows:
Low Retardation Factor greater than 1,000
Medium Retardation Factor between 10 and 1,000
High Retardation Factor less than 10
Reference refers to citations listed in the Bibliography at the end of this manual
Persistence score is based on the "Degradation Rate" as follows:
Low Degradation Rate greater than 19/yr.
Medium Degradation Rate between 0.0069/yr and 19/yr.
High Degradation Rate less than 0.0069/yr.
BEJ Best Engineering Judgment
This entry has been approved; IRIS input is pending (HEAST document).
-------
Concentration Score
ST
?• 8
O
o
I
I
o
o
o
m
5
O
CO
O
o
1
o
33
I
III
-------
119
Form S.2
Toxicity, Concentration, Mobility and Persistence Scores ;-
by Contaminant/Mixture and Source Category
Source Category: Agrichemical Application
Com Crop - Pesticides
Non-carcinogens:
Com Crop - Fertilizers
Non-carcinogens:
Soybean Crop - Pesticides
Carcinogens:
Non-carcinogens:
Soybean Crop - Fertilizers
Non-carcinogens:
Cotton Crop - Pesticides
Non-carcinogens:
Cotton Crop - Fertilizers
Non-carcinogens:
Wheat Crop - Pesticides
Non-carcinogens:
Wheat Crop - Fertilizers
Non-carcinogens:
Other Crops - Pesticides
Non-carcinogens:
Contaminant
dicamba
other pesticides
nitrate-nitrogen
trifluralin
other pesticides
— -- - -
nitrate-nitrogen
aldicarb1
aldicarb2
nitrate-nitrogen
aldicarb1
aldicarb2
nitrate-nitrogen
aldicarb1
aldicarb2
NOTES:
1 High irrigation, any soil type
2 Medium irrigation, loamy sandy soil, or
REFERENCES:
Pesticides: 9,31,32,
Fertilizers: 1 , 6, 26
49, 70
Toxicity
Score
0.0
-0.1
-1.5
1.3
-0.2
-1.5
1.3
1 .3
-1.5
1.3
1.3
-1.5
1.3
1:3
sandier
Cone.
Score
-1.2
0.6
1.5
-0.6
0.1.
-0.2
0.3
-0.6
1.1
0.3
-0.6
0.9
0.3
-0.6
Mobility
H
M
H
L
M
H
H
H
H
H
H
H
H
H
Persistence
M
M
M
M
M
•
M
M
M
M
M
M
L
M
M
-------
Form S.2 ^ ' ,\:(_1, , -
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category: Container Storage and Material Transfer
Toxicity
Contaminant Score
Cone.
Score
il
^ V
i ~*|
1
Mobility Persistence
HAZARDOUS WASTE/ACCUMULATION
I D001
I
D002
F001:
F003:
|_.
RCRA
D001:
F003:
X500:
: Ignitable Wastes
Carcinogens:
Non-carcinogens:
: Corrosive Wastes
Non-carcinogens:
•
- benzene - i
methanol
organics mix1
methanol
toluene
2.0
-1.2
-0.4
-1.2
-1.0
2.1
2.0
2.5
1.6
1.6
M -
H
H
H
M
L
H
L
H
L
Spent, Halogenated Solvents Used For Degreasing
Carcinogens:
Non-carcinogens:
chloroform
carbon tetrachloride
organics mix2
1.2
2.5
-0.3
2.0
2.0
2.5
H
M
M
M
M
L
Spent. Non-Halogenated Solvents
Carcinogens:
Non-carcinogens:
PERMITTED STORAGE
Ignitable Wastes
Carcinogens:
Non-carcinogens:
Spent, Non-Halogenated
Carcinogens:
Non-carcinogens:
benzene
methyl ethyl ketone
• benzene
methanol
organics mix1
Solvents
benzene
methyl ethyl ketone
2.0
-0.2
2.0
-1.2
-0.4
2.0
-0.2
2.0
2.0
2.1
2.0
2.5
2.0
2.0
M
H
M
H
H
M
H
L
L
L
H
L
»
L
L
Ignitable Waste Mixtures
Carcinogens:
Non-carcinogens:
benzene
organics mix1
2.0
-0.4
2.0
2.4
M
H
L
L
-------
121
Form S.2
Toxicity, Concentration, Mobility and Persistence Scores
by .Contaminant/Mixture and Source Category
' 1 J ^ •? f S < ** "*
Source Category; Container Storage and Material Transfer
Toxicity Cone.
Contaminant Score Score Mobility Persistence
X501: Corrosive Waste Mixtures
Non-carcinogens: chromium mix3
lead
X504: Toxic Waste Mixtures
Carcinogens: chloroform
carbon tetrachloride
Non-carcinogens:
organics mix4
-1.2
1.3
1.2
2.5
-0.2
1.6 H
-1.0 M
H
H
2.0 H M
2.0 M L
2.3 M M
HAZARDOUS MATERIALS/PRODUCTS
Petroleum (gasoline)
Carcinogens: benzene
Petroleum (diesel)
Carcinogens: benzene
Chemical/Cleaning Liquids (corrosive)
Non-carcinogens:
Sulfuric Acid
Non-carcinogens:
Paint Dryer (flammable)
Carcinogens:
Non-carcinogens:
acetic acid
sulfuric acid
benzene
organics mix 1B
organics mix 2*
2.0
2.0
-1.5
-1.2
2.0
-0.2
-0.4
-2.7
-2.7
2.4
3.3
2.9
3.2
3.3
M
M
H
H
M
H
M
H
L
L
NOTES:
1 acetone and methylethyl ketone
2 1,2-dichlorobenzene
3 chromium and methanol
4 1,1,1-trichloroethane
6 methyl ethyl ketone, cresol and acetone
8 xylene, napthalene, toluene and 1,1,1-trichloroethane
REFERENCES:
Hazardous Waste Treatment, Hazardous Waste Storage: 25
Product Storage:
Petroleum: 12
Chemical: 25, 40
-------
122
;-- •- ^ ^ "i^;?^, t^4^i:v'-"'^
Tpxlcity, Concentration, Mob Hity and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category: Injection Wells/Deep Wells {Classes 1, II, and
Toxicity Cone.
Contaminant Score Score Mobility
Class 1: Wastewater Disposal
Carcinogens: benzene 2.0 -1.8 M
Non-carcinogens: chromium mix1 -1 .2 1 .6 H
cyanide 0.2 -0.4 H
Class II: Oil and Gas Activity
Carcinogens: arsenic 3.7 -4.7 H
benzene 2.0 -3.3" M
Non-carcinogens: boron -0.5 -2.0 M
Class III: Mineral Extraction - Metals Mining
Carcinogens: arsenic 3.7 -2.6 H
Non-carcinogens: metals mix 1 3 -0.8 -0.3 H
metals mix 23 0.3 0.3 M
NOTES:
1 chromium and sulfuric acid
2 chromium, manganese and barium
3 nickel, vanadium, mercury, iron, cadmium, zinc, berylium, silver and lead
REFERENCES:
Class 1: 54
Class II: 63
Class III: 9
^
V>- *>
• ;
Persistence
L
H
L
H
L
H
H
H
H
-------
123
, , ,JFotmS.Z ',
Toxicity, Concentration, Mobility and Persistence Scores
*by Contaminant/Mixture and Source Category
Source Category: Injection Wells/Shallow Wells (Class V)
Toxicfty
Contaminant Score
Cone.
Score
Mobility
Persistence
AGRICULTURAL DRAINAGE WELLS
Com Crop
Non-carcinogens:
Soybean Crop
Carcinogens:
Non-carcinogens:
Other Crops
Non-carcinogens:
-
dicamba
other pesticides
nitrate-nitrogen
trifluraiin
other pesticides
nitrate-nitrogen
aldicarb
nitrate-nitrogen
0.0
-0.1
-1.5
1.3
-0.2
-1.5
1.3
-1.5
-4.9
-3.1
-2.2
-4.3
-3.6
-4.3
-3.6
-2.6
H
M
H
L
M
H
H
H
M
M
M
M
M
M
M
M
AUTOMOBILE SERVICE STATION DISPOSAL WELLS
Service and Repair
Carcinogens:
Non-carcinogens:
Body Shops
Non-carcinogens:
Car Washing
Carcinogens:
Non-carcinogens:
arsenic
chromium
metals mix1
chromium
metals mix1
arsenic
chromium
metals mix1
3.7
0.7
1.3
0.7
1.5
3.7
0.7
1.3
-4.0
-3.4
-1.5
-1.6
-2.8
I. ».»«.;«.... .,.,»»»,
-4.9
-4.8
-4.0
H
H
M
H
M
H
H
M
H
H
H
H
H
H
H
H
INDUSTRIAL PROCESS WATER DISPOSAL WELLS
Low Throughput (less than 2.6 million gallons/year)
Non-carcinogens:
methanol
cyanide mix2
metals mix3
-1.2
-1.0
-0.2
-2.9
-2.6
-2.5
H
H
M
H
L
H
-------
124
f _
Toxicity, Concentration, Mobility and Persistence Scores
y & > x — <:
by Contaminant/Mixture and Source Category
Source Category: injection Weils/Shallow Wells (Class V)
Toxidty Cone.
Contaminant Score Score
Mobility Persistence
Medium Throughput (between 2.6 and 31.2 million gallons/year)
Inorganic Chemical Manufacture
Non-carcinogens:
chromium
cyanide
metals mix4
0.7
0.1
-0.4
Laundry and Cleaning Services
Non-carcinogens: tetrachloroethylen
0.5
-4.0
-3.7
-2JI
-1.3
High Throughput (more than 31.2 million gallons/year)
Electroplating
Non-carcinogens:
chromium
cyanide
metals mix6
0.7
0.1
-0.3
Cooling waters
Non-carcinogens:
chromium
0.7
-4.0
-3.7
-2.0
-3.7
H
H
M
M
H
M
M
H
H
Ml
H
H
M
H
H
NOTES:
1 cadmium and lead
2 cyanide, phenol and acetone
3 iron, boron and silver
4 nickel, mercury, zinc and lead
6 nickel, zinc, iron, silver, cadmium and lead
REFERENCES:
Agricultural Drainage Wells:
Pesticides: 70,49
Fertilizers 70, 9
Automobile Service Station Disposal Wells:
Service and repair, body shops, and car washing:
Industrial Process Water Disposal Wells:
Low throughput: 25, 52
Medium throughput: 25, 50
High throughput: 25,51,53
14
-------
125
y^lgl^ipiy^^^^^:..^ FormS.2
£1 ? M 1 S IMfcity? Cbnce^iij'atibn, Mobility and Persistence Scores
Si :::5:xfelrS PlllbV-Co'ntaifilnant/IVIixture and Source Category
,- v.v' '•:'•. ;.",:''.;" .;-.". ... -. v;.v. , /, ;. :X'*':'";:'.:! .. •':-:••••: .•'•"'>---:::::S:-:':::v!-:
ia f|- ?> ^|;::|1 :i:; plPlfflif - r - '
f;;-;-; :?y;;:-t. <^^^--f^., : ^:F" Source Category: Land Treatment
Contaminant
Petroleum Refining:
Carcinogens: arsenic
benzene
Non-carcinogens: metals mix 1 1
metals mix 22
Inorganic Chemicals:
Non-carcinogens: chromium {total)
metals mix3
Organic Chemicals:
Non-carcinogens: chromium (total)
metals mix4
NOTES:
1 chromium and barium
2 lead, vanadium, nickel and zinc
3 chromium, zinc and nickel
4 lead, zinc and cadmium
Toxicrty Cone.
Score Score Mobility
3.7 -1.5 H
2.0 -0.9 M
0.4 -0.6 H
0.8 -0.6 M
0.8 -0.9 H
-0.5 -2.0 M
0.8 -1.8 H
0.0 -1.6 M
Persistence
H
L
H
H
H
H
H
H
REFERENCES:
Petroleum refining, inorganic chemicals, and organic chemicals: 22, 23
-------
126
•1 Mi iffv,
Form S.2 ^ t ^ ^ ^
Toxlcity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category: Landfills
Toxicfty Cone.
Contaminant Score Score Mobility Persistence
Hazardous Waste ("Subtitle C" Sites) and Municipal Waste ("Subtitle D" Sites) pre-1976
Carcinogens: arsenic 3.7 -2.6 H H
benzene 2.0 -2.4 M L
Non-carcinogens: chromium 0.7 -2.0 H H
Municipal Waste ("Subtitle D" Sites) post-1976
Carcinogens:
Non-carcinogens:
arsenic
organics mix1
iron
3.7
3.4
0.5
-5.0
-3.5
-1.2
H
H
M
H
L
H
NOTES:
1 vinyl chloride and dichloromethane
REFERENCES:
Hazardous Waste/Municipal Waste (pre-1976):
Municipal Waste:
21,60
42
-------
127
Form'S.2
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
f -f.f -J- s
Source Category: Material Transport
Toxicity
Contaminant Score
Cone.
Score
Mobility
A
Persistence
HAZARDOUS WASTE TREATMENT
D001:
D002:
F001:
Ignitable Wastes
Carcinogens:
Non-carcinogens:
Corrosive Wastes
Non-carcinogens:
benzene
methanol
organics mix1
methanol
toluene
2.0
-1.2
-0.4
-1.2
-1.0
2.1
2.0
2.5
1.6
.1.6
M
H
H
H
M
L
H
L
H ..
L
Spent, Halogenated Solvents Used for Degreasing
Carcinogens:
chloroform
carbon tetrachloride
F003:
Non-carcinogens:
Spent, Non-Halogenated
Carcinogens:
organics mix2
Solvents
benzene
Non-carcinogens: methyl ethyl ketone
RCRA
D001:
F003:
PERMITTED STORAGE
Ignitable Wastes
Carcinogens:
Non-carcinogens:
Spent, Non-Halogenated
Carcinogens:
benzene
methanol
organics mix1
Solvents
benzene
Non-carcinogens: methyl ethyl ketone
X500:
Ignitable Waste Mixtures
Carcinogens:
Non-carcinogens:
benzene
organics mix1
1.2
2.5
-0.3
2.0
-0.2
2.0
-1.2
-0.4
2.0
-0.2
2.0
-0.4
2.0
2.0
2.5
2.0
2.0
2.1
2.0
2.5
2.0
2.0
2.0
2.4
H
M
M
M
H
M
H
H
M
H
M
H
M
L
M
L
' L
,
L
H
L
L
L
L
t
-------
128
""'•~ ' •'"' ' lForrnS-2, * * J^?*?'',' ;"'%",V«fc - "'
Toxicity, Concentration, Mobility and Persistence Scores ^s
'by' Contaminant/Mixture and Source Category ' " ' * T •••"
Source Category: Material Transport
Toxicity Cone.
Contaminant . Score Score
X501 : Corrosive Waste Mixtures
Non-carcinogens: chromium mix3 -1 .2 1 .6
lead 1 .3 -1 .0
X504: Toxic Waste Mixtures
Carcinogens: chloroform 1.2 2.0
carbon tetrachloride 2.5 2.0
Non-carcinogens: organics mix* -0.2 2.3
HAZARDOUS MATERIALS/PRODUCTS
Petroleum (gasoline)
Carcinogens: benzene 2.0 -2.7
Petroleum (diesel)
Carcinogens: benzene 2.0 -2.7
Chemical/Cleaning Liquids (corrosive)
Non-carcinogens: acetic acid -1 .5 2.4
Sulfuric Acid
Non-carcinogens: sulfuric acid -1.2 3.3
Paint Dryer (flammable)
Carcinogens: benzene 2.0 2.9
Non-carcinogens: organics mix 1 6 -0.2 3.2
organics mix 28 -0.4 3.3
NOTES:
1 acetone and methyl ethyl ketone
2 1 ,2-dichlorobenzene
3 chromium and methanol
4 1,1,1 -trichloroethane
6 methyl ethyl ketone, cresol and acetone
a xylene, napthalene, toluene and 1,1,1-trichloroethane
REFERENCES:
Hazardous Waste Treatment, Hazardous Waste Storage: 25
'Product Storage:
Petroleum: 1 2
Chemical: 25, 40
' ' '%>*\ i
-:
Mobility Persistence
H H
M H
H M
M L
M M
M L
M L
H L
HLJ
rl
M L
H L
M L
-------
129
Form S.2
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category: Pipelines
Contaminant
Sewer
Carcinogens: chloroform
benzene
bis(2-ethylhexyl)phthalate
Non-carcinogens: chromium
Other (Includes Petroleum)
Carcinogens benzene
Toxicfty
Score
1.2
2.0
1.5
0.7
2.0
Cone.
Score
-4.8
-4.7
-4.3
-3.8
-2.3
Mobility Persistence
H M
M L
L H
H H
M L
REFERENCES:
Other: 69
-------
130
Form S.2
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
«*. 1 * "CM. •$&}•*> 4 ** *
Source Category: Septic Tank Systems
Toxicity Cone.
Contaminant Score Score Mobility Persistence
Septic Tank Systems
Non-carcinogens:
nitrates
-1.5
-0.7
H
REFERENCES: 21
-------
131
Form S,2 ' ' "" 7
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category: Storage Piles
Toxicity
Contaminant . Score
HEAP LEACHING PILES
Carcinogens:
Non-carcinogens:
arsenic
metals mix 1 1
metals mix 22
3.7
-0.8
0.3
NON-HEAP LEACHING PILES/HAZARDOUS WASTE PILES"
D002 & DOO6: Corrosive Materials Waste & Cadmium
Carcinogens: arsenic 3.7
Non-carcinogens: sulfuric acid -1 .2
metals mix3 -1 .3
D008: Lead Waste
Non-carcinogens:
F001 : Spent Halogenated
Carcinogens:
Non-carcinogens:
lead
Solvents Used in Degreasing
dichloroethane
1,1,1 -trichloroethane
1.3
2.4
-0.5
Cone.
Score Mobility .Persistence
-2.6
-0.3
0.3
1.6
2.7
4.3
-1.0
2.3
2.3
F006: Waste water Treatment Sludges from Electroplating, Except Aluminum,
Non-carcinogens: metals mix 1* 0.6 -0.1
cyanide 0.2 -1.1
metals mix 2B 0.4 -0.6
F019: Waste from the Chemical Converson Coating of Aluminum
Non-carcinogens: metals mix 14 -0.1 -1.5
cyanide 0.2 -0.3
metals mix 2s -0.8 -1.7
K048. K049, K050. K051
Carcinogens:
Non-carcinogens:
: Sludges from the Petroleum
arsenic
benzene
metals mix 1*
metals mix 27
Refining
3.7
2.0
0.3
0.8
Industry
-2.2
-1.2
-0.6
-0.6
H
H
M
H
H
M
M
H
M
Tin or Zinc
H
H
M
H
H
M
H
M
H
M
H
H
H
H
H
H
H
L
M
H
M
H
H
M
H
H
L
H
H
-------
132
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category:
Contaminant
A1\ \£f "'$fJ>J.V,'$&ft,
Storage
Toxicity
Score
tples^f
Cone.
Score
Mobility
„ jtot ^i
Persistence
K061 : Emission Control Dust/Sludges from Steel Production
Carcinogens:
Non-carcinogens:
NONHAZARDOUS WASTE
Non-carcinogens:
MATERIAL STOCKPILES
Carcinogens:
Non-carcinogens:
MINE WASTE PILES
Copper Sector
Carcinogens:
Non-carcinogens:
Lead Sector
Carcinogens:
Non-carcinogens:
Zinc/Zinc Oxide
Carcinogens:
Non-carcinogens:
Aluminum Sector
Carcinogens:
arsenic
chromium (VI)
metals mix6
PILES
chromium
metals mix8
arsenic
metals mix 1 *
metals mix 210
arsenic
metals mix11
arsenic
metals mix11
arsenic
manganese
metals mix11
arsenic
3.7
0.8
0.6
0.7
0.6
3.7
-0.8
0.4
3.7
1.4
3.7
1.3
3.7
-0.8
1.6
3.7
-1.3
0.0
-0.8
-0.4
-0.8
-5.5
-1.7
-3.2
-5.4
-3.9
-5.5
-1.8
-5.2
-4.0
-2.3
-4.5
H
H
M
H
M
H
H
M
hi
M
H
M
H
H
M
M
H
H
H
H
t-
H
H
H
H
H
H
H
H
H
H
H
-------
133
Form S.2
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
- Source Category: Storage Piles
NOTES:
1
2
3
4
5
9
7
8
9
10
11
chromium, manganese and barium
nickel, vanadium, mercury, iron, cadmium, zinc, beryiium, silver and lead
tin and lead
chromium and barium
nickel, lead, zinc and cadmium
nickel and zinc
cyanide, vanadium, lead and zinc
chromium, nickel, cadmium, zinc and lead
chromium and manganese
lead, nickel, beryiium, cadmium, iron and mercury
cadmium and lead
REFERENCES:
Heap Leaching Piles:
Hazardous Waste Piles:
Nonhazardous Waste Piles:
Material Stockpiles:
Mine Waste Piles:
29
15,22,23, 24,62
27
49
61
-------
134
Form S.2 - < . *
Toxicity, Concentration, Mobility and Persistence Scores
by Contamianant/Mixture and Source Category
*«*,'*„**• , S v
v ' „„ C^'-<^& '**
Source Category: Surface impoundments
Contaminant Toxicfty
Score
Hazardous Waste ("Subtitle
Carcinogens:
Non-carcinogens:
C")
arsenic
benzene
chromium
metals mix1
3.7
2.0
0.7
1.3
Cone.
Score
-1.8
-0.3
-1.3
-1.0
Mobility
H
M
H
M
Persistence
H
L
H
H
Industrial Waste ("Subtitle D")
Carcinogens:
Non-carcinogens
Municipal Waste Treatment
Carcinogens:
Non-carcinogens:
ANIMAL FEEDLOTS
Dirt Lot Runoff:
Non-carcinogens:
Paved Lot:
Non-carcinogens:
MINE TAILING PONDS
Copper Sector:
Carcinogens:
Non-carcinogens:
Lead Sector:
Carcinogens:
Non-carcinogens:
chloroform
organics mix2
nitrobenzene
Ponds ("Subtitle D")
chloroform
benzene
chromium
nitrate
nitrate
arsenic
manganese
metals mix3
arsenic
metals mix3
1.2
1.8
1.8
1.2
2.0
0.7
-1.5
-1.5
3.7
-0.8
1.7
3.7
1.6
-3.6
-3.2
-3.6
-4.8
-4.7
-3.8
-1.5
-0.4
-1.8
-1.7
-1.6
-4.5
-2.4
H
M
H
H
M
H
H
H
H
H
M
H
M
M
L
L
M
M
H
M
M
H
H
H
H
H
-------
135
Form S.2
Toxicity, Concentration, Mobility and Persistence Scores
by Contamianant/Mixture and Source Category
Source Category; Surface Impoundments
Contaminant Toxicity Cone.
•_ Score Score Mobility Persistence
Zinc/Zinc Oxide:
Carcinogens: arsenic 3.7 -5.2 H H
Non-carcinogens: metals mix3 1.5 -3.1 M H
Aluminium Sector:
Carcinogens: arsenic 3.7 -3.0 H H
Urban Stormwater Retention Ponds
Carcinogens: arsenic 3.7 1.4 H H
Non-carcinogens: chromium 0.7 2.0 H H
._ metals mix4 0.2 2.0 M H
NOTES:
1 cyanide, cadmium and lead
2 benzene, and 2,4,6 trichlorophenol
3 cadmium and lead
4 zinc, lead, cadmium and nickel
REFERENCES:
Hazardous Waste (Subtitle C): 21
Industrial Waste (Subtitle D): 21
Municipal Waste Treatment Ponds (Subtitle D): 28 . .
Animal Feedlots: 48
Mine Tailing Ponds: 61
Urban Stormwater Retention Ponds: 70
-------
136
• -"" - -'- FormS.2 " ' ^
Toxicity, Concentration, Mobility .and Persistence Scores
by Contaminant/Mixture, and Source Category
Source Category: Tanks - ^
Toxicity
Contaminant Score
HAZARDOUS WASTE TREATMENT/DISTILLATION
D001: Ignhable Wastes
Carcinogens: benzene
Non-carcinogens: methanol
organics mix1
F003: Spent, Non-Halogenated Solvents
Carcinogens: benzene
Non-carcinogens: methyl ethyl ketone
organics mix2
X907: Chlorinated Pesticide Production Wastes
Carcinogens: chloroform
hexachlorobenzene
Non-carcinogens: hexachloro-
cyclopentadiene
OXIDATION/REDUCTION PRECIPITATION
D007: Chromium Waste
Non-carcinogens: chromium
FOQ6: Wastewater Treatment Sludges from Electroplating
Non-carcinogens: chromium
metals mix3
2.0
-1.2
-0.4
2.0
-0.2
-0.8
1.2
3.7
0.6
0.7
0.7
0.2
K048: Dissolved Air Flotation Waste From the Petroleum Refining
Non-carcinogens: chromium
lead
HAZARDOUS WASTE STORAGE/ACCUMULATION
D001: Ignhable Wastes
Carcinogens: •• benzene
Non-carcinogens: methanol
organics mix1
0.7
1.3
2.0
-1.2
-0.4
Cone.
Score
2.1
2.0
2.5
2.0
2.0
2.3
2.0
2.0
2.0
-0.3
0.8
0.6
Industry
-2.4
-1.6
2.1
2.0
2.5
Mobility
M
H
H
M
H
M
H
M
M
H
H
M
H
M
M
H
H
\ ~-
Persistence
L
H
L
L
L
L
M
M
M
H
H
H
H
H
L
H
L
-------
137
, Form S.2
- _ Toxicity , Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category: Tanks
Toxicity
Contaminant Score
D002: Corrosive Wastes
Non-carcinogens: methanol
toluene
F001: Spent, Halogenated Solvents Used for Degreasing
Carcinogens: chloroform
carbon tetrachloride
Non-carcinogens: organics mix*
F003: Spent, Non-Halogenated Solvents
Carcinogens: benzene
Non-carcinogens: methyl ethyl ketone
RCRA PERMITTED STORAGE
D001: Ignhable Wastes
Carcinogens: benzene
Non-carcinogens: methanol
organics mix1
F003: Spent, Non-halogenated Solvents
Carcinogens: benzene
Non-carcinogens: methyl ethyl ketone
X500: Ignitable Waste Mixtures
Carcinogens: benzene
Non-carcinogens: organics mix'
X501 : Corrosive Waste Mixtures
Non-carcinogens: chromium mix6
lead
X504: Toxic Waste Mixtures
Carcinogens: chloroform
carbon tetrachloride
Non-carcinogens: organics mix6
-1.2
-1.0
1.2
2.5
-0.3
2.0
-0.2
2.0
-1.2
-0.4
2.0
-0.2
2.0
-0.4
-1.2
1.3
1.2
2.5
-0.2
Cone.
Score
1.6
1.6
2.0
2.0
2.5
2.0
2.0
2.1
2.0
2.5
2.0
2.0
2.0
2.4
1.6
-1.0
2.0
2.0
2.3
Mobility
H
M
H
M
M
M
H
M
H
H
M
H
M
H
H
M
H
M
M
Persistence
H
L
M
L
M
L
L
L
H
M
L
L
L
L
H
H
M
L
M
-------
138
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
Source Category: Tanks
Contaminant
Toxicity Cone.
Score Score Mobility Persistence
SMALL QUANTITY GENERATORS
Above Ground Tanks
Stream 1: Hoigenated Spent Solvents and Ignitable Wastes
Carcinogens: chloroform 1.2 2.0 H
carbon tetrachloride 2.5 2.0 M
Non-carcinogens: 1,1,1-trichloroethane -0.5 2.0 M
Stream 2: Non-Halogenated Spent Solvents and Ignitable Wastes
Carcinogens: benzene 2.0 2.0 M
Non-carcinogens: organics mix1 -0.4 2.4 H
Stream 3: Strong Acid or Alkaline Waste
Non-carcinogens: lead 1.3 -0.3 M
M
L
M
L
L
H
Below Ground Tanks
Stream 1: Halogenated Spent Solvents and Ignitable Wastes
Carcinogens: chloroform 1.2 2.0 H
carbon tetrachloride 2.5 2.0 M
Non-carcinogens: 1,1,1-trichloroethane -0.5 2.0 M
Stream 2: Non-halogenated Spent Solvents and Ignitable Wastes
Carcinogens: benzene 2.0 2.0 M
Non-carcinogens: organics mix1 -0.4 0.5 H
Stream 3: Strong Acid or Alkaline Waste
Non-carcinogens: lead 1.3 -0.3 M
M
L
M
L
L
H
PRODUCT STORAGE
Petroleum (gasoline)
benzene
Carcinogens:
Petroleum (diesel)
Carcinogens: benzene
Chemical/Cleaning Liquids (corrosive)
Non-carcinogens: . acetic acid
2.0
2.0
-1.5
-2.7
-2.7
2.4
M
M
H
-------
139
Form S»2
Toxicity, Concentration, Mobility and Persistence Scores
by Contaminant/Mixture and Source Category
v "> r f ^ : f
- Source Category: Tanks
Contaminant
Toxicity Cone.
Score Score Mobility Persistence
Sulfuric Acid
Non-carcinogens:
Paint Dryer (flammable)
Carcinogens:
Non-carcinogens:
sulfuric acid
benzene
organics mix 17
organics mix 2s
-1.2
2.0
-0.2
-0.4
3.3
2.9
3.2
3.3
H
M
H
M
H
L
L
L
MUNICIPAL ("SUBTITLE D") WASTEWATERS
Carcinogens: chloroform 1.2 -4.8 H
benzene 2.0 -4.7 M
bis(2-ethylhexyl)phtalate 1.5 -4.3 L
Non-carcinogens: chromium 0.7 -3.8 H
M
L
H
H
NOTES:
1 acetone and methyl ethyl ketone
2 xylene and toluene
3 cadmium, lead and nickel
4 1,2-dichlorobenzene
8 chromium and methanol
6. 1,1,1 -trichloroethane
7 methyl ethyl ketone, cresol and acetone
8 xylene, napthalene, toluene and 1,1,1 -trichloroethane
REFERENCES:
Hazardous Waste Treatrnent, Hazardous Waste Storage and Small Quantity Generators:
Product Storage:
Petroleum: 12
Chemical: 25, 40
Municipal Waste waters: 28
25
-------
-------
141
CHAPTER 4:
SOURCE DATASHEETS,
SOURCE WORKSHHEETS,
AND TRANSPORT WORKSHEET
-------
-------
SOURCE DATASHEET - AGRICHEMICAL APPLICATION
Source #: Author: _
Source Name: Date:
Location:
143
StepS
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Age of Source
SD2 Area of Application
Indicate the number of years
agrichemicals have been applied
to the crop land
Indicate the number of acres
within the WHPA to which agri-
chemicals are applied.
years
acres
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
144
SOURCE DATASHEET - AGRICHEMICAL APPLICATION (continued)
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD3 Distance Score
Use the tattle below to determine
the Distance Score as a function
of the shortest distance from the
area of agrichemical application to
the well (or to an abandoned well if
one exists between the area of agri-
chemical application and the well). For
example, if the shortest distance between
the area of agrichemical application
and the well is 1,000 feet, then the
Distance Score is equal to 2.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320 - 2640
402-805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0-3.0
5280 - 15,840
1610-4829
5
3.0-5.0
15,840 - 26,400
4829 - 8040
6
SD4 Does the source discharge
directly to a conduit
system (e.g., pipes'or
utility chase) that could
transport contaminants
directly to the well?
Yes or No
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2). • '
-------
145
SOURCE DATASHEET - AGRICHEMICAL APPLICATION (continued)
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD5 Contaminant Data
Complete the Contaminant Data Table
below for all pesticides and fertilizers
that are applied to crop land. If you
know the pesticides and fertilizers that
are applied as well as their application
rates (expressed in units of kilograms/hectare/
year), then use Contaminant Form S.I. Since
a particular agrichemical may be used
sporadically, multiply its application rate by
the percentage of time that it is used. For
example, if the pesticide Metolachor has been
applied for three years on a a farm that has
used agrichemicals for 15 years, then multiply
the application rate of Metolachor by 0.2 (i.e.,
the percentage of tune that Metolachor has been
used, or 3 divided by 15). If you do not know
which pesticides and fertilizers are applied,
then use Contaminant Form S.2. Form S.2
provides default pesticides and fertilizers and
their contaminant scores by various crop types.
Keeping in mind that crops may be rotated, enter
onto the Contaminant Data Table below all pesticides
and fertilizers that are applied to the crop land.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
•'
Persistence
Score
For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
-------
147
SOURCE WORKSHEET
AGRICHEMICAL APPLICATION
-------
148
Step 6
SOURCE #
SOURCE WORKSHEET - AGRICHEMICAL APPLICATION
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Likelihood of Release (L,) Score
Set L, = 0.
QUANTITY (Q)
Step 2 Determine the Area Score
Likelihood of Release (L^ Score = 0
Use the graph below to determine
the Area Score as a function of
the Area of Application (SD2).
Area Score by Application Area
10
100 1000
AFM of Application (Acrac)
10000
100000
Area Score:
-------
149
SOURCE WORKSHEET - AGRICHEMICAL APPUCATION (continued)
STEP INSTRUCTIONS SCORE
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration Score
(SD5) + Area Score (Step 2)
Contaminant or Contaminant Mixture Quantity Score (Q)
(1)
(2)
(3) ;
-------
-------
151
SOURCE DATASHEET - CONTAINER STORAGE AND MATERIAL TRANSFER Step 5
Source #: Author:
Source Name: Date:
Location:
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Throughput Cateogry
Enter 1, 2, 3,4, or 5 to indicate
the number of 55-gallon drums
passing through the storage and/or
transfer facilities hi one year, where:
1 = 1-10 Drums
2 = 11-100 Drums
3 == 101-500 Drums
4 = 501-1000 Drums
5 = 1000+Drums
SD2 Duration of Storage
Enter Low, Medium, or High for the
average duration of storage of the
55-gallon drums where:
Low = < 30 days
Medium = 31 days - 1 year; or
High = 1 year*
If materials are just transferred and
not stored, enter Low.
SD3 Storage Area Design
SD4 Container Storage and/
or Material Transfer
Age
Indicate whether the storage area is
padded or unpadded.
Enter the number of years that
hazardous materials have been
stored and/or transferred within
the WHPA.
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
152
SOURCE DATASHEET - CONTAINER STORAGE AND MATERIAL TRANSFER (continued)
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD5 Distance Score
Use Contaminant Form S. 1
to determine the Distance Score
as a function of the distance
from the container storage area
to the well (or to an abandoned
well if one exists between the
source and the well). For
example, if the distance between
the source and the well is 175
meters, then the Distance Score
is equal to 1.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320 - 2640
402 - 805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0 - 3.0
5280 - 15,840
1610 - 4829
5
3.0-5.0
15,840-26,400
4829 - 8040
6
SD6 Does the source discharge
. directly to a conduit
system (e.g., pipes or
utility chase) that could
transport contaminants
directly to the well?
Yes or No
* Fpr additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - CONTAINER STORAGE AND MATERIAL TRANSFER (continued)
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD7 Contaminant Data
Use Contaminant Forms S.I or S.2
to complete the Contaminant Data
Table below. Refer to Task 2 of
the User's Guide for additional
guidance. ;
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
-------
155
SOURCE WORKSHEET
CONTAINER STORAGE AND
MATERIAL TRANSFER
-------
156
Step 6
SOURCE #
SOURCE WORKSHEET - CONTAINER STORAGE AND MATERIAL TRANSFER
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Determine the Likelihood of Release (Lt) Score
Use the table below to determine the
Likelihood of Release (L,) Score as a
function of the Throughput Category (SD1),
Duration of Storage (SD2), and Storage Area
Design (SD3).
Likelihood of Release Score by Throughput Category,
Duration of Storage, and Storage .Area Design
Duration
of
Storage
Low
Medium
High
Storage
Area
Design
Not Applicable
Unpadded
Padded
Unpadded
Padded
Throughput Category
1
-2.8
-2.1
-2.6
-1.3
-2.3
2 '•
-1.8
-1.6
-2.1
-1.3
-2.3
3
-1.1
-1.2
-1.7
-L3
-2.3
4
-0.7
-1.0
-1.5
• -1.3
• -2.3
5
-0.4
-0.9
-1.4
-1.3
-2.3
Likelihood of Release (L,) Score =
-------
157
SOURCE WORKSHEET - CONTAINER STORAGE AND MATERIAL TRANSFER (continued)
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2 Determine the Volume Score
Use the table below to determine
the Volume Score as a function of
the Throughput Category (SD1) and
Duration of Storage (SD2). i
Volume Score by Throughput Category and Duration of Storage
Duration
of Storage
Low
Medium
High
Throughput Category
1
-0.7
-0.7
-0.7
2
-0.7
-0.2
0.3
3
-0.7
0.2
1.0
4
-0.7
0.3
1.3
5
-0.7
0.8
2.3
Volume Score:
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration Score
(SD7) + Volume Score (Step 2)
Contaminant or Contaminant Mixture
(1)
(2)
(3) ___
Quantity Score (Q)
-------
-------
159
SOURCE DATASHEET - DEEP INJECTION WELLS (CLASSES I, H, HI) . Step 5
Source #: -Author:
Source Name: Date:
Location: _.
PARAMETER INSTRUCTIONS* VALUE
This datasheet covers Injection Wells falling into one of the following classes:
Class I: Wastewater disposal
Class II: Oil and gas activity
Class HI: Mineral extraction
Class IV Wells have been banned and are not covered hi this manual. However, if you have a Class IV
well in the WHPA, you should consider it a high risk and should investigate further. Class V wells are
covered in the "Shallow Injection/Drainage Well" source category.
DESIGN PARAMETERS
SD1 Well Age
years
SD2 Throughput Rate Determine the amount of liquid
injected into the well annually mgy
Typical default values for each well
class are: .
Class I: 20.7 million gallons/year (Ref. 54)
Class II: 5.3 million gallons/year (Ref. 63)
Class III: 19.4 million gallons/year (Refs. 13 and 71)
A typical default value for the number
of wells in a Class m mining operation
is 110. Therefore, the Throughput Rate
for a 110-well mining operation is 2,139
million gallons/year (Ref. 71).
For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
160
SOURCE DATASHEET - DEEP INJECTION WELLS (CLASSES I, H, HI) (continued)
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD3 Distance Score
Use the table below to determine
the Distance Score as a function
of the shortest distance from the
injection well to the well (or to an
abandoned well if one exists between
the injection well and the well).
For example, if the shortest distance
between the injection well and the well
is between 1/4 and 1/2 mile, men the
Distance Score is equal to 3.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320-2640
402-805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0 - 3.0
5280-15,840
1610 - 4829
5
3.0 - 5.0
15,840 - 26,400
4829 - 8040
6
SIM Does the source discharge
directly to a conduit
system (e.g., pipes or
utility chase) that could
transport contaminants
directly to the well?
Yes or No
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
161
SOURCE DATASHEET - DEEP INJECTION WELLS (CLASSES I, II, HI) (continued)
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD5 Contaminant Data
Use Contaminant Forms S.I or S.2 to
complete the Contaminant Data Table
below. Refer to Task 2 of the User's
Guide for additional guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
-------
163
SOURCE WORKSHEET
INJECTION WELLS: DEEP WELLS
(CLASSES I, H, AND HI)
-------
164
Step 6
SOURCE #
SOURCE WORKSHEET -!
INJECTION WELLS
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Determine the IJkelihood of Release (L,) Score
6
g
CC
"o
•g
•0.8
•0.9
•1.0
•1.1
-1.2
-1.3
-1.4
-1.5
-1.6
-1.7
-1.8
-1.9
-2.0
•2.1
-2.2
-2.3-
•2.4-
-2.5
Use the graph below to determine the
Likelihood of Release (L,) Score as a
function of Well Age (SD1).
Likelihood of Release Score by Well Age
10 15 20 25 30 35 40
Well Ag* (Y*ar«)
Likelihood of Release (It-,) Score =
(Ref. 21)
-------
165
SOURCE WORKSHEET - DEEP INJECTION WELLS (continued)
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2
Determine the Volume Score
Determine the Volume Score for the
well based on Throughput Rate (SD2).
If you are using default values for
the Throughput Rate, the corresponding
default values for the Volume Score
are as follows:
Class I: 3.8 (Refs. 21 and 54)
Class H: 3.2 (Refs. 21 and 63)
Class ni: 3.8 for a single well in a mining operation
5.8 for a 110-well mining operation
(Refs. 21,13, and 71)
If you are using a site-specific rate, use
the graph below to determine the Volume Score.
Volume Score by Throughput Rate
I 4
I 3
o
2-
.1
10 100 1000
Throughput Rat* (Million Gallons/Yaw)
1000C
Volume Score:
-------
166
SOURCE WORKSHEET - DEEP INJECTION WELLS (continued)
STEP
INSTRUCTIONS
SCORE
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration Score
(SD5) + Volume Score (Step 2)
Contaminant or Contaminant Mixture
(1)
(2)
(3).
Quantity Score (Q)
Step 4 Set LU and A^ in Transport Worksheet Equal to 0
Steps 4 and 6 of the Transport Worksheet
provide guidance for determining LU and Av
for each contaminant/mixture at each
source. For Deep Injection Wells, override
the LU and Ay calculations in those steps
and set LU and AU equal to 0 for each
contaminant/mixture.
-------
'•*£.'
167
SOURCE DATASHEET - INJECTION WELLS: SHALLOW WELLS (CLASS V) Step 5
Source #: Author:
Source Name: Date:
Location: .
PARAMETER INSTRUCTIONS* VALUE
This datasheet covers a wide variety of drainage wells that fall under the category of Class V Injection
Wells. Specifically, in this datasheet,, you can evaluate:
1. Automobile Service Station Disposal Wells (5X28)
2. Industrial Process Water and Water Disposal Wells (5W20)
3. Agricultural Drainage Wells (5F01).
Note that Injection Wells falling into Classes I-m are covered in the "Deep Injection Well" source
category. Also, Class IV wells have been banned and are not covered in this manual. However, if you
have Class IV wells in the WHPAS you should consider them as high risk and investigate them further.
Class V Storm Water Drainage Wells (5DO2) are covered in the "Surface Impoundment" source
category.
DESIGN PARAMETERS
SD1 Well Age
years
SD2 Throughput Rate Determine the amount of liquid
drained or injected into the well million
: annually. Default Volume Scores gallons/year
are provided below. If wells are
clustered at the source, add all
the throughput rates to get an
aggregate Throughput Rate.
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
168
SOURCE DATASHEET - INJECTION WELLS; SHALLOW WELLS (CLASS V) (continued)
PARAMETER INSTRUCTIONS* VALUE
1. Automobile Service Station Disposal Wells: A typical default value is 0.6 million gallons/year
(Ref. 69).
Use for the following industries: car washes, auto body repair shops, car dealerships, and
specialty repair shops (transmission, muffler, etc.).
2. Industrial Process Water and Water Disposal Wells: Industrial drainage throughput can vary
significantly from facility to facility, so it is important to try to get the actual drainage
throughput for the facility in your area. However, if that information is not available, you can
select one of the following default values, based on facility type:
Low Throughput (< 2.6 million gallons per year): 0.6 million gallons/year
Use for the following industries: Measuring, Analyzing, and Controlling Instruments;
Photographic, Medical and Optical Goods.
Medium Throughput (2.6 - 31.2 million gallons per year): 9.4 million gallons/year
Use for the following industries: Industrial Inorganic Chemicals; Laundry, Cleaning, and
Garment Services.
High Throughput (> 31.2 million gallons per year): 54.6 million gallons/year.
Use for the following industries: Engraving and Allied Services - Electroplating Manufacturing
Industries; NEC; Electric, Gas and Sanitary Services (Ref. 69).
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
169
SOURCE DATASHEET - INJECTION WELLS: SHALLOW WELLS (CLASS V) (continued)
PARAMETER
INSTRUCTIONS*
VALUE
3. Agricultural Drainage Wells: For agricultural drainage wells, determine the total area being
drained in acres.
Area:
acres
With this information and with the net infiltration rate parameter (WD4) from the Wellhead
Datasheet, use the following table to determine the Throughput Rate for the drainage well.
Assume a Net Infiltration of > 15 inches if the agricultural well is irrigated.
Agricultural Drainage Well Throughput Rate
by Area and Net Infiltration (Million Gallons/Year) (Ref. 70)
Area::(Acres) 7
<10
10-100
101 - 1,000
1,001 - 10,000
10,001 - 100,000
> 100,000
Net Infiltration (Inches)
t;.C:-<'0.6-'. .;;
0.0068
0.068
0.68
6.8
68
680
Otf-6
0.027
.0.27
2.7
27
270
2,700
$-15
0.27
2.7
27
270
2,700
27,000
>15
0.54
5:4
54
540
5,400
54,000
For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
170
SOURCE DATASHEET - INJECTION WELLS: SHALLOW WELLS (CLASS V) (continued)
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD3 Distance Score
You will need to look up the Distance
Score on Form S.I, as a function
of the shortest distance from the
injection well to the well (or to an
abandoned well if one exists between
the injection well and the well).
For example, if the shortest distance
between the injection well and the well
is between 1/4 and 1/2 mile, then the
Distance Score is equal to 3.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320-2640
402 - 805
3
.5 - 1.0
2640-5280
805 - 1610
4
1.0-3.0
5280-15,840
1610 - 4829
5
3.0-5.0
15,840-26,400
4829 - 8040
6
SD4 Does the source discharge
directly to a conduit system
(e.g., pipes or utility
chase) that could transport
contaminants directly to the
well?
Yes or No
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
171
SOURCE DATASHEET - INJECTION WELLS: SHALLOW WELLS (CLASS V) (continued)
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETER!;
SD5 Contaminant Data
Use Contaminant Form S.I or S.2 to
complete the Contaminant Data Table
below. Refer to Task 2 of the User's
Guide for additional guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
-
Persistence
Score
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
-------
173
SOURCE WORKSHEET
INJECTION WELLS: SHALLOW WELLS
(CLASS V)
-------
174
Step 6
SOURCE#
SOURCE WORKSHEET - INJECTION WELLS: SHALLOW WELLS
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Determine the Likelihood of Release (Lz) Score
The Likelihood of Release (LJ Score is 0
for all Shallow Injection/Drainage Wells.
Likelihood of Release (L,) Score =
QUANTITY (Q)
Step 2 Determine the Volume Score
Use the graph below to determine the
Volume Score for the well or cluster of
wells based on the Throughput Rate (SD2).
Volume Score by Throughput Rate
.001
Throughput Rat* (Million Galtons/YMr)
Volume Score:
-------
175
SOURCE WORKSHEET - INJECTION WELLS: SHALLOW WELLS (continued)
STEP INSTRUCTIONS SCORE
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration Score
(SD5) + Volume Score (Step 2)
Contaminant or Contaminant Mixture Quantity Score (Q)
(1) ' -.
(2) __
(3)
-------
-------
Source #:
Source Nape:
Location:
SOURCE DATASHEET -LAND TREATMENT
Author:
Date:
177
StepS
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Unit Age
Indicate the age of the land
treatment unit in years.
years
SD2 Land Treatment Area
Provide the number of acres
within the WHPA to which wastes
are applied. A typical land
treatment unit has an area of 15
acres (Ref. 10).
acres
SD3 Waste Application Score
Obtain the Waste Application Score
as a function of the average waste
application rate as follows:
0-10 wet tons/acre, enter 1
11-100 wet tons/acre, enter 2
101-500 wet tons/acre, enter 3
501-1000 wet tons/acre, enter 4
> 1000 wet tons/acre, enter 5
For inactive land treatment units,
assume a Waste Application Score of 1.
A typical Waste Application Score
for the petroleum refining and inorganic
chemical industries is 2. A typical
Waste Application Score for the organic
chemical industry is 1 (Ref. 11).
* For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - LAND TREATMENT (continued)
178
PARAMETER
INSTRUCTIONS*
VALUE
IIYDROGEOLOGIC SETTINGS
SD4 Distance Score
Use the table below to determine the
Distance Score as a function of the
shortest distance from the land treat-
ment unit area to the well (or to an
abandoned well if one exists between
the land treatment unit and the well).
For example, if the shortest distance
between the land treatment area and the
well is between 1/4 and 1/2 mile, then
the Distance Score is equal to 3.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
' 1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320 - 2640
402 - 805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0 - 3.0
5280 - 15,840
1610 - 4829
5
3.0-5.0
15,840 - 26,400
4829 - 8040
6
SD4 Does the source discharge
directly to a conduit
system (e.g., pipes or
utility chase) that could
transport contaminants
directly to the well?
Yes or No
* For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - LAND TREATMENT (continued)
179
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD6 Contaminant Data
Use Contaminant Form S.I or S.2 to
complete the Contaminant Data Table
below. Refer to Task 2 of the User's
Guide for additional guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
* .For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
-------
181
SOURCE WORKSHEET
LAND TREATMENT
-------
182
Step 6
SOURCE #
SOURCE WORKSHEET - LAND TREATMENT
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Likelihood of Release (L,) Score
Set L! = 0.
QUANTITY (Q)
Step 2 Determine the Area Score
Likelihood of Release (Lj) Score = 0
Use the graph below to determine the
Area Score as a function of Land
Treatment Area (SD2).
Area Score by Land Treatment Area
100
Land TrMrtment ArM (Act**)
1000
10000
Area Score:
-------
SOURCE WORKSHEET - LAND TREATMENT (continued)
153
STEP
INSTRUCTIONS
SCORE
Step 3 Determine the Release Score
Use the table below to determine the
Release Score as a function of the
Waste Application Score (SD3) and
Net Infiltration (WD4).
Release Score by Waste Application Score and Net Infiltration
'..""'-."•>Wasfe-:-':''-;-.i
Application
Score
1
2
3
4
5
Net Infiltration (Inches)
:..•:-'- *°-6 • •••?
-2.2
-1.9
-1.4
-1.1
-0.8
0.6-6
-1.6
-1.5
-1.2
-1.0
-0.7
6-15
-0.6
-0.6
-0.5
-0.5
-0.4
St 15
-0.3
-0.3
-0.3
-0.2
-0.2
Release Score:
(Ref. 70)
Step 4 Compute the Volume Score
Volume Score = Release Score (Step 3)
+ Area Score (Step 2)
Volume Score:
Step 5 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Volume Score (Step 4)
+ Concentration Score (SD6)
Contaminant or Contaminant Mixture Quantity Score (Q)
(1)
(3).
-------
-------
185
SOURCE DATASHEET - LANDFILLS Step 5
Source #: __. Author:
Source Name: Date:
Location:
PARAMETER INSTRUCTIONS* VALUE
LANDFILL DESIGN PARAMETERS
SD1 Landfill Design Enter 1, 2, 3, 4, or 5 for the
design of the landfill where:
1 =: Unlined vegetative cover
2 -• Clay-lined vegetative cover
3 = Synthetic liner + synthetic
cover + leachate collection
system
4 = Unlined + clay and synthetic
cover
5 = Clay and synthetic liner +
clay and synthetic cover +
leachate collection system
If the landfill design is unknown:
Select" 1" for all municipal waste
landfills and hazardous (industrial)
waste landfills with a last year of
active operation prior to 1976; or
select "5" for hazardous waste landfills
: : with a last year of active operation
after 1976 (Ref. 59).
The table on the next page will help to
determine the landfill design in Step SD1.
* For additional guidance, especially for contaminant-specific data (SD8), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - LANDFILLS (continued)
186
PARAMETER
INSTRUCTIONS*
VALUE
Landfill Design Options by Last Year of Active
Operation and Waste Type Managed
• ::Lasf::Year:df-;'""':'::"';
Active Operation
Prior to 1976
Post 1976
Waste Type
Managed*
All Types
Hazardous Waste
Municipal Waste
Landfill
Design Options
1,2,3
4,5
1, 2, 3, 4, 5
* A landfill that receives hazardous waste is referred to as a "Subtitle C" landfill
by current Federal regulations and a landfill that receives municipal waste is referred
to as a "Subtitle D" landfill
SD2 Landfill Status
Enter 1, 2, or 3 for the status of
of the landfill where:
1 = Active. •
2 = Post-closure care
3 = Abandoned or post-care
SD3 Default Assumptions
Do you use a default assumption
for either landfill design or land-
fill status? Circle either "yes"
or "no."
Yes No
SD4 Landfill Age
Indicate the age of the landfill.
years
SD5 Landfill Area
Estimate the landfill area, in acres.
For landfills over 100 acres, round
to the nearest 100 acres.
acres
For additional guidance, especially for contaminant-specific data (SD8), refer to the User's Guide
(Chapter 2).
-------
SOURCE;DATASHEET -LANDFILLS (continued)
187
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD6 Distance Score
Use the table below to determine die
Distance Score as a function of the
shortest distance from the landfill
to the well (or abandoned well if one
exists between the landfill and the
well). For example, if the shortest
distance between the landfill and the well
is between 1/4 and 1/2 mile, then the
Distance Score is equal to 3.
Distance Scoring Form
Distance
from .
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320 - 2640
402 - 805
3
.5 - 1.0
2640-5280
805 - 1610
4
1.0-3.0
5280-15,840
1610 - 4829
5
3.0-5.0
15,840-26,400
4829 - 8040
6
SD7 Does the source discharge
directly to a conduit system
(e.g., pipes or utility
chase) that could transport
contaminants directly to
the well?
Circle either "Yes" or "No"
Yes No
For additional guidance, especially for contaminant-specific data (SD8), refer to the User's Guide
(Chapter 2).
-------
188
SOURCE DATASHEET - LANDFILLS (continued)
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD8 Contaminant Data
Use Contaminant Form S.I to complete the Contaminant
Data Table below with site-specific information.
If no site-specific information is available, use
default contaminants provided in Tables 1 or 2 below.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
Table 1. Contaminant Data Table for Subtitle D (Municipal) Landfills Opened After 1976
1
2
3
Contaminant/Mixture
Score
Arsenic
Dichloromethane
Iron
Toxicity
Score
3.7
3.4
0.5
Concentration
. Score
-5
-3.5
-1.2
Mobility
Score
H
H
M
Persistence
Score
H
H
H
Table 2. Contaminant Data Table for Subtitle D (Municipal) Landfills Operating Before 1976,
and AH Subtitle C (Hazardous Waste) Landfills
1
2
3
Contaminant/Mixture
Score
Arsenic
Chromium and
cyanide
Other metals
Toxicity
Score
3.7
0.8
1.4
Concentration
Score
-1
-3.6
-3.3
Mobility
Score
H
H
M
Persistence
Score
H
H
H
For additional guidance, especially for contaminant-specific data (SD8), refer to the User's Guide
(Chapter 2).
-------
189
SOURCE WORKSHEET
LANDFILLS
-------
SOURCE WORKSHEET - LANDFILLS
190
Step 6
SOURCE*
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Determine the Likelihood of Release (Lj) Score
Use the table below to determine Lj
as a function of Landfill Design (SD1),
Landfill Status (SD2), and Landfill
Age (SD4).
Likelihood of Release Score by Landfill Design,
Landfill Status, and Landfill Age
Landfill
Design (SD1)
1 - Unlined and vegetative cover
2 - Clay-lined and synthetic cover
3 - Synthetic liner, synthetic cover,
and leachate collection system
4 - Unlined, and clay and synthetic
cover
5 - Clay and synthetic liner, clay
and synthetic cover, and
leachate collection system
Landfill Status (SD2) and Landfill Age (SD4)
•• . r
Active
1-5 years
0
-2.0
-0.3
0
*
> 5 years
0
-1.7
0
0
*
2
Post-Closure
Care
0
-0.5
0
0
-1.5
3
Abandoned
or Post-Care
0
0
0
0
0
Likelihood of Release (L,) Score =
(Ref. 59)
-------
SOURCE WORKSHEET - LANDFILLS (continued)
191
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2
Determine the Area Score
Read the Area Score from the
following graph as a function of
the Landfill Area (SD5).
7.0
3.0
Area Score by Landfill Area
Landfill Ara» (Aerve)
Area Score:
-------
192
SOURCE WORKSHEET - LANDFILLS (continued)
STEP
INSTRUCTIONS
SCORE
Step 3 Determine the Release Score
You will need the following information:
»• the net infiltration parameter that was identified on the Wellhead Datasheet (WD4)
> the landfill design (SD1)
»• the landfill status (SD2).
First select the table that corresponds
to your landfill status. Then, determine
the Release Score based on landfill
design and net infiltration. If the
table indicates a value of*," set Release
Score, Volume Score (Step 4), and the
Quantity Scores (Step 5) all equal to "*."
Release Score by Landfill Status, Landfill Design, and Net Infiltration
Landfill Status = 1 (Active)
Landfill
Design (SD1)
land 4
2
3
5
Net Infiltration (Inches)
0-0.6
-2.5
-4.0
*
*
0.6-6
-1.7
-3.0
*
*
6-15
-1.0
-1.5
-2.0
*
£15
-0.7
-1.2—
-1.6
*
Landfill Status = 2 (Post-Closure Care)
Landfill
Design (SD1)
1
2
3
4
5
Net Infiltration (Inches)
0-0.6
-2.2
-2.4
-2.8
-2.5
-3.1
0.6-6
-1.7
-1.9
-2.0
-1.9
-3.1
6-15
-0.7
-1.0
-1.4
-1.2
-1.8
fclS
-0.3
-0.5
-1.4
-1.0
-1.8
-------
SOURCE WORKSHEET - LANDFILLS (continued)
193
STEP
INSTRUCTIONS
SCORE
Landfill Status = 3 (Abandoned or Post-Care)
Landfill
Design (SD1)
All Designs
Net Infiltration (Inches)
0-0.6
-2.2
0.6-6
-1.7
6-15
4.7
2rI5
-0.3
Release Score:
(Ref. 59)
Step 4 Compute the Volume Score
Volume Score = Area Score (Step 2)
+ Release Score (Step 3)
(Note: If Release Score is "*," then
enter a Volume Score of "*.")
Step 5 Compute the Quantity Score (Q) for Each Contaminant
Volume Score:
Quantity Score (Q) = Volume Score (Step 4)
+ Concentration Score (SD8)
(Note: If Volume Score is"*," then
enter a Quantity Score (Q) of "*" for
all contaminants.)
(1)
(2)
(3)
Contaminant or
Contaminant Mixture
Concentration
Score (SD8)
Volume
Score
Quantity
Score (Q)
-------
-------
Source #:
Source Name:
Location:
SOURCE DATASHEET - MATERIAL TRANSPORT
. Author:
Date:
195
StepS
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Road Density
Enter Low, Medium, or High for the
density of roads within the WHPA that
are used to transport hazardous materials
where:
Low =1-10 miles of roads
Medium = 11-100 miles
High = > 100 miles
SD2 Frequency of Shipments
Enter Low, Medium, or High for the
frequency of hazardous material shipments
per year where:
Low = 1 -10 shipments/year
Medium = 11 - 100 shipments/year
High = > 100 shipments/year
If you do not know the number of shipments
per year, use the following:
Low = WHPA is in a non-urban area* and is
not intersected by an interstate
Medium = WHPA is hi a non-urban area and
is intersected by an interstate, or is
hi an urban area and is not intersected
by an interstate
High = WHPA is hi an urban area and is
intersected by an interstate.
* Note: an urban area is defined as a central
city or central core that has a population of
at least 50,000 people.
For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
196
SOURCE DATASHEET - MATERIAL TRANSPORT (continued)
PARAMETER
INSTRUCTIONS*
VALUE
SD3 Age
Enter the estimated number of years
that hazardous materials have been
transported through the WHPA.
years
HYDROGEOLOGIC SETTINGS
SD4 Distance Score
Use the table below to determine
the Distance Score as a function
of the distance from the source to
the well (or to an abandoned well if
one exists between the source and the
well). Use the distance between
the wellhead and the section of road
(used to transport hazardous materials)
that is nearest to the wellhead.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 - .25
635 - 1320
193-402
2
.25 -.5
1320 - 2640
402 - 805
3
.5 - 1.0
2640 - 5280
805 - 1610
4 -
1.0 - 3.0
5280-15,840
1610 - 4829
5 ••
3.0 - 5.0
15,840 - 26,400
4829-8040 -
6
SDS Does the source discharge Yes or No
directly to a conduit system
(e.g., pipes or utility
chase) that could transport
contaminants directly to
the well?
* For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - MATERIAL TRANSPORT (continued)
197
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD6 Contaminant Data
Use Contaminant Forms S.I or S.2 to
complete the Contaminant Data Table
below. Refer to Task 2 of the User's
Guide for additional guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
* For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
-------
199
SOURCE WORKSHEET
MATERIAL TRANSPORT
-------
SOURCE WORKSHEET - MATERIAL TRANSPORT
200
Step 6
SOURCE #
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE
Step 1 Determine the Likelihood of Release (Lt) Score
Read Lt from the table below as a function
of Road Density (SD1) and Frequency of
Shipments (SD2).
Likelihood of Release Score by Frequency of
Shipments and Road Density
Frequency of
Shipments
Low
Medium
High
Road Density
Low
-5.0
-4.0
-3.0
Medium
-4.0
-3.0
-2.0
High
-3.0
-2.0
-1.0
Likelihood of Release (Lj) Score =
(Ref. 20)
-------
201
SOURCE WORKSHEET- MATERIAL TRANSPORT (continued)
STEP INSTRUCTIONS SCORE
QUANTITY (Q)
Step 2 Compute the Quantity Score (Q)
for Each Contaminant
For each contaminant that is
transported within the WHPA, determine
a separate Quantity Score as a function
of the Contaminant Concentration Score
and a constant Release Score of 1.1
(Ref. 20).
Quantity Score (Q) = Concentration
Score (SD6) + 1.1
Contaminant or Contaminant Mixture Quantity Score (Q)
(2)
(3)
-------
-------
203
SOURCE DATASHEET - PIPELINES
Source #:
Source Name:
Location:
StepS
Author:
Date:
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Pipeline Type
Choose one of the following types
of pipelines: Sewer or Other
(includes Petroleum).
SD2 Age of Pipeline
Enter the age of the pipeline system.
years
SD3 Annual Throughput
Obtain values for throughput from
sewage treatment plant or pipeline
company officials. If the total annual
sewage throughput through the WHPA
is unknown, assume an annual throughput
per person of 27,375 gallons. If the
sewage treatment plant is located within
the WHPA, multiply this value by the
city population to determine the Annual
Throughput. Otherwise, multiply this
value by the number of people living
in the WHPA to determine the Annual
Throughput.
million
gallons/year
(Ref. 8)
SD4 Pipeline Length
Indicate the length, hi miles, of
pipeline within the WHPA for Other
(Petroleum) pipelines only.
miles
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
204
SOURCE DATASHEET - PIPELINES (continued)
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD5 Distance Score
Use the table below to determine the Distance
Score as a function of the shortest distance
from the pipeline to the well (or to an abandoned
well if one exists between the source and the
well). For example, if the shortest distance
between the pipeline and the well is 1,000 feet,
then the Distance Score is equal to 2.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320 - 2640
402 - 805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0 - 3.0
5280 - 15,840
1610 - 4829
5
3.0-5.0
15,840 - 26,400
4829 - 8040
6
SD6 Does the source discharge Yes or No
directly to a conduit system
(e.g., pipes or utility
chase) that could transport
contaminants directly to
the well?
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
.(Chapter 2).
-------
SOURCE DATASHEET - PIPELINES (continued)
205
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD7 Contaminant Data
Use Contaminant Forms S.I or S.2 to
complete the Contaminant Data Table
below. Refer to Task 2 of the User's
Guide for additional guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
, Score
-
Persistence
Score
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
-------
207
SOURCE WORKSHEET
PIPELINES
-------
SOURCE WORKSHEET - PIPELINES
208
Step 6
SOURCE #
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE
Step 1 Determine the Likelihood of Release (Lt) Score
For Sewer Pipelines, set Lt = 0.
For Other Pipelines (e.g., petroleum),
use the table below to determine the
Likelihood of Release Score as a function
of the Pipeline Length (SD4) and the Age
of Pipeline (SD2).
Likelihood of Release Scores for Other (e.g., Petroleum)
Pipelines by Age and Pipeline Length
Pipeline
Length
(Miles)
1-10
11-20
> 20
Age (Years) "
< 10
-0.6
-0.3
0:0 .
10-20
-0.3
0.0
0.0
>20
0.0
0.0
0.0
Likelihood of Release (L,) Score =
(Ref. 39)
-------
SOURCE WORKSHEET - PIPELINES (continued)
209
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2
Determine the Volume Score (Q)
Use the graph below to determine the
Volume Score as a function of Pipeline
Type (SD1) and Annual Throughput (SD3).
6 H
Volume Score by Annual Throughput and Pipeline Type
-&• Sewer Lines
•*• Other Pipelines
10 100 1000
Annual Throughput (Million Gallons/Year)
10000
Volume Score:
(Ref. 26)
Step 3 Compute the Quantity Score
Quantity Score (Q) = Concentration
Score (SD7) + Volume Score (Step 2)
Contaminant or Contaminant Mixture
(1)
(2)
(3)
Quantity Score (Q)
-------
-------
211
Source #:
Source Name:
Location:
SOURCE DATASHEET - SEPTIC TANK SYSTEMS
Author:
Date:
StepS
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Septic System Age
SD2 Total Sewage Throughput See Note below.
Estimate the average age of the septic
systems in question
years
thousand gallons/year
(ref. 37)
Annual Sewage Throughput by Number and Type of Units Using Septic Systems
(Thousands of Gallons per Year)
Septic
System
Type
Houses
Apartments
Small Businesses
- ' Number of Units** ' -.- "
1-20
1,095
438
241
21-50
3,504
1,402
771
, 51-150
10,950
4,380
2,409
151-500
35,040
10,402
7,709
501 *
109,500
43,800
24,090
**
For houses, the number of units is the number of houses.
For apartments, the number of units is the number of individual apartments.
For small businesses, the number of units is the number of individual small retailers such as gift
and novelty stores and sporting goods stores.
Note: Use the table above to calculate the Total Sewage Throughput as a function of the number and
type (house, apartment, or small business) of units using septic systems. For apartments, the number
of units is the number of individual apartments using septic systems. For small businesses, include
retailers whose throughput would include sanitary wastes only, such as gift and novelty stores and
sporting goods stores. For example, if there is a cluster of about 25 houses, 60 apartments, and 20
small businesses that use septic systems, then the Total Sewage Throughput would equal 3,504 +
4,380 + 241, i.e., 8,125 thousand gallons/year.
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - SEPTIC TANK SYSTEMS (continued)
212
PARAMETER
INSTRUCTIONS*
VALVE
IIYDROGEOLOGIC SETTINGS
SD3 Distance Score
Use the table below to determine the Distance
Score as a function of the distance from the
source to the well (or to an abandoned well if
one exists between the source and the well).
Use the shortest distance from any one unit using"
a septic system to the well. For example, if
the shortest distance between any one unit using
a septic system and the well is 1,000 feet, then
the Distance Score is equal to 2.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 -.5
1320 - 2640
402-805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0 - 3.0
5280 - 15,840
1610 - 4829
5
3.0-5.0
15,840 - 26,400
4829 - 8040
6
SD4 Does the source discharge Yes or No
directly to a conduit system
(e.g., pipes or utility
chase) that could transport
contaminants directly to
the well?
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - SEPTIC TANK SYSTEMS (continued)
213
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD5 Contaminant Data
Use Contaminant Forms S.I or S.2 to complete
the Contaminant Data Table below. Refer
to Task 2 of the User's Guide for additional
guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide
(Chapter 2).
-------
-------
215
SOURCE WORKSHEET
SEPTIC TANK SYSTEMS
-------
216
Step 6
SOURCE #
SOURCE WORKSHEET - SEPTIC TANK SYSTEMS
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Likelihood of Release (L,) Score
Set Lj = 0.
QUANTITY (Q)
Step 2 Determine the Volume Score
Likelihood of Release (Lj) Score = 0
Use the graph below to determine '
the Volume Score as a function of
the Total Sewage Throughput (SD2)
and the Septic System Age (SD1).
Volume Score by Total Sewage Throughput and Septic System Age
10 100 1000 10000 100000 1000000
Total Smng* Throughput (Thousand GaUona/Yaar)
Volume Score:
(Ref. 26)
-------
217
SOURCE WORKSHEET - SEPTIC TANK SYSTEMS (continued)
STEP INSTRUCTIONS SCORE
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Volume Score (Step 2)
+ Concentration Score (SD5)
Contaminant or Contaminant Mixture Quantity Score (Q)
(1) .
(2)
(3) ' • '
-------
-------
219
Source #:
Source Name:
Location:
SOURCE DATASHEET - STORAGE PILES
Author:
Date:
Step 5
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Storage Pile Type
Circle the appropriate storage pile
type: "Non-Heap Leaching" or "Heap
Leaching." "Heap-Leaching" storage
piles are associated with metals mining.
All other storage piles are "Non-Heap
Leaching."
Non-Heap Leaching
Heap Leaching
SD2 Storage Pile Design
Enter 1, 2, or 3 for the Storage Pile
Design, where:
1 = No liner or pile
2 = Clay, concrete, or asphalt pad
3 = Single synthetic liner with
leachate collection system.
SD3 Storage Pile Area
Estimate the area of the Storage Pile,
in acres.
acres
SD4 Storage Pile Age
Indicate the age of the Storage Pile.
years
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2). .
-------
SOURCE DATASHEET - STORAGE PILES (continued)
220
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD5 Distance Score
Use the table below to determine the Distance
Score as a function of the shortest distance
from the storage pile to the well (or to an
abandoned well if one exists between the
storage pile and the well). For example,
if the shortest distance between the storage
pile and the well is between 1/4 and 1/2 mile,
then the Distance Score is equal to 3.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25-5
1320 - 2640
402 - 805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0-3.0
5280 - 15,840
1610-4829
5
3.0 - 5.0
15,840 - 26,400
4829 - 8040
6
SD6 Does the source discharge
directly to a conduit
system (e.g., pipes or
utility chase) that could
transport contaminants
directly to the well?
Yes or No
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide.
(Chapter 2).
-------
SOURCE DATASHEET - STORAGE PILES (continued)
221
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD7 Contaminant Data
Use Contaminant Forms S.I or S.2 to complete
the Contaminant Data Table below. Refer
to Task 2 of the User's Guide for additional
guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
.For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide.
(Chapter 2).
-------
-------
224
Step 6
SOURCE#
SOURCE WORKSHEET - STORAGE PILES
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE
Step 1 Determine the Likelihood of Release (Lt) Score
Use the table below to determine the
Likelihood of Release Score (L,) as a
function of Storage Pile Design (SD2).
The Likelihood of Release Score accounts
for failure of the pad or synthetic liner.
Design No.
1 — No Liner or Pad
2 - Clay, Concrete, or Asphalt Pad
3 — Single Synthetic Liner with Leachate
Collection System (LCS)
Likelihood of Release Score
0
-1.0
-2.0
Likelihood of Release (LJ Score =
(Refs. 5, 16, and 59)
-------
if*
223
SOURCE WORKSHEET
STORAGE PILES
-------
SOURCE WORKSHEET - STORAGE PILES (continued)
225
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2
Determine the Area Score
Use the graph below to determine the
Area Score as a function of Storage
Pile Area (SD3).
Area Score by Storage Pile Area
100
Storage Pile Area (Acres)
1000
10000
Area Score:
-------
226
SOURCE WORKSHEET - STORAGE PILES (continued)
STEP
INSTRUCTIONS
SCORE
Step 3 Determine the Release Score
Depending on the Storage Pile Type
(SD1), use one of the two tables below
to determine the Release Score. If the
Storage Pile is Non-Heap Leaching, then
use the table below to determine the
Release Score based on the Storage Pile
Design (SD2) and the net infiltration
rate determined in the Wellhead Datasheet
(WD4).
Non-Heap Leaching Storage Pile Release Score
by Storage Pile Design and Net Infiltration
Storage
Pile Design
(SD2)
1
2
3
Net Difiitrathm (Inches)
0-0.6
-2.2
-2.7
-3.2
0.6-6
-1.6
-2.1
-2.6
«-15
-0.6
-1.1
-1.6
>1S
-0.3
-0.-7
-1.3
(Refs. 19 and 59)
If the storage pile is Heap-Leaching,
then use the table below to determine
the Release Score based on the Storage
Pile Design (SD2).
Heap-Leaching Storage Pile Release
Score by Storage Pile Design
Storage Pile Design
1
2
3
— No Liner or Pad
- Clay, Concrete, or Asphalt Pad
- Single Synthetic Liner with LCS
Release Score
-0.1
-0.5
-1.2
(Refs. 19, 35, and 59)
-------
227
SOURCE WORKSHEET - STORAGE PILES (continued)
STEP INSTRUCTIONS SCORE
Step 4 Determine the Volume Score
Volume Score = Area Score (Step 2)
+ Release Score (Step 3)
Volume Score:
Step 5 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration
Score (SD7) + Volume Score (Step 3)
Contaminant or Contaminant Mixture Quantity Score (Q)
(1) __ '
-------
-------
Source #:
Source Name:
Location:
SOURCE DATASHEET - SURFACE IMPOUNDMENTS
•• • Author:
Date:
229
StepS
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Surface Impoundment
Design
Enter 1, 2, or 3 for the design
of the Surface Impoundment, where:
1 = No liner
2 = Clay liner
3 = Clay and synthetic liner
(Ref. 41)
SD2 Surface Impoundment
Area
Estimate the area of the Surface
Impoundment, in acres.
acres
SD3 Surface Impoundment
Age
Indicate the age of the impoundment.
years
* For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
230
SOURCE DATASHEET - SURFACE IMPOUNDMENT (continued)
PARAMETER
INSTRUCTIONS*
VALUE
HYDROGEOLOGIC SETTINGS
SD4 Distance Score
Use the table below to determine the
Distance Score as a function of the
shortest distance from the surface
impoundment to the well (or to an
abandoned well if one exists between
the surface impoundment and the well).
For example, if the shortest distance
between the surface impoundment and the
well is between 1/2 and 1 mile, then the
Distance Score is equal to 4.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25-5
1320 - 2640
402 - 805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0-3.0
5280 - 15,840
1610 - 4829
5
3.0-5.0
15,840 - 26,400
4829 - 8040
6
SDS Does the source discharge Yes or No
directly to a conduit system
(e.g., pipes or utility
chase) that could transport
contaminants directly to
the well?
For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - SURFACE IMPOUNDMENT (continued)
231
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD6 Contaminant Data
Use Contaminant Forms S.I or S.2
to complete the Contaminant Data
Table below. Refer to Task 2 of the
User's Guide for additional guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
* For additional guidance, especially for contaminant-specific data (SD6), refer to the User's Guide
(Chapter 2).
-------
(1
-------
233
SOURCE WORKSHEET
SURFACE IMPOUNDMENTS
-------
234
Step 6
SOURCE #
SOURCE WORKSHEET - SURFACE IMPOUNDMENTS
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (L,)
Step 1 Determine the Likelihood of Release (LJ Score
Use the table below to determine the
Likelihood of Release Score (Lt) as a
function of Impoundment Design (SD1).
The Likelihood of Release Score accounts
for liner failure over a twenty-year
active life.
Design No.
1 — No Liner
2 — Clay Liner
3 — Clay and Synthetic Liner
Likelihood of Release Score
0
0
-1.5
Likelihood of Release (L,j) Score =
(Ref. 59)
-------
235
SOURCE WORKSHEET - SURFACE IMPOUNDMENTS (continued)
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2 Compute the Volume Score
Use the graph below to determine the
Volume Score as a function of Surface
Impoundment Area (SD2).
I
i
Volume Score by Surface Impoundment Area
1 . 10 100
ATM of Surfao* ImpeundiMNt (*•!»•)
1000
Volume Scorer;
Step 3 Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration
Score (SD6) + Volume Score (Step 2)
(Refs. 19 and 59)
Contaminant or Contaminant Mixture
(1)
(2)
(3)
Quantity Score (Q)
-------
-------
Source #:
Source Name:
Location:
SOURCE DATASHEET - TANKS
Author:
Date:
237
StepS
PARAMETER
INSTRUCTIONS*
VALUE
DESIGN PARAMETERS
SD1 Number of Tanks
SD2 Tank Size
SD3 Tank Design
You may want to group tanks containing similar
contaminants and of similar size, design, age
and distance from the wellhead. You need
not determine the exact number of tanks;
rather, determine if the number of tanks is
within one of the following ranges: 1, 2-5,
6-25, 26-75, or > 75.
Enter Small, Medium, or Large for the size of
each tank or group.
Small = < 5,000 gallons each
Medium = 5,000 - 30,000 gallons each
Large = > 30,000 gallons each
Enter the tank number using the information
hi the table on the next page (Refe. 12 and 25).
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - TANKS (continued)
238
PARAMETER
INSTRUCTIONS*
VALUE.
Tank Design
Design
Description - -'" - \",lxl"- " ''^VJ^;./. "- ""'l: ,„" ^ -;*
A. Hazardous Waste, Chemical, and Petroleum Storage Tanks
1
2
3
4
5
6
7
Above-ground bare steel tank resting on cradles on a concrete pad with curbing.
The tank capacity is less than or equal to 30,000 gallons (small or medium).
Above-ground bare steel tank resting on-grade on a concrete pad with curbing.
The tank capacity is greater than or equal to 30,000 gallons (large).
In-ground concrete tank with an open top at ground level.
Below-ground bare steel tank.
Below-ground double-walled steel tank with interstitial monitoring.
Below-ground STiP3 tank (cathodically protected).
Below-ground fiber-reinforced plastic (FRP) tank.
B. Hazardous Waste and Wastewater Treatment Tanks
8
9
10
Above-ground bare steel tank resting on cradles on a concrete pad with curbing.
The tank capacity is less than or equal to 30,000 gallons (small or medium).
Above-ground bare steel tank resting on-grade on a concrete pad with curbing.
The tank capacity is greater than or equal to 30,000 gallons (large).
In-ground concrete tank with an open top at ground level.
C. Hazardous Waste Small Quantity Generator and Farm Storage Tanks
11
12
Above-ground bare steel tank resting on cradles.
Below-ground bare steel tank.
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - TANKS (continued)
239
PARAMETER
INSTRUCTIONS*
VALUE
SD4 Tank Age
Enter the age of the tank or the average
age of the tanks in the group.
year(s)
HYDROGEOLOGIC SETTINGS
SD5 Distance Score
Use the table below to determine the Distance
Score as a function of the shortest distance
from the tank(s) to the well (or to the
abandoned well if one exists between the tank(s)
and the well). For example, if the
shortest distance between the tank(s) and the
well is between 1/2 and 1 mile, then the
Distance Score is equal to 4.
Distance Scoring Form
Distance
from
Source
to Well
(Miles)
(Feet)
(Meters)
Distance Score
0-.12
0-635
0-193
1
.12 -.25
635 - 1320
193-402
2
.25 - .5
1320-2640
402 - 805
3
.5 - 1.0
2640 - 5280
805 - 1610
4
1.0-3.0
5280 - 15,840
1610-4829
5
3.0 - 5.0
15,840 - 26,400
4829 - 8040
6
SD6 Does the source discharge
directly to a conduit
system (e.g., pipes or
utility chase) that could
transport contaminants
directly to the well?
Yes or No
* For additional guidance, especially for contaminant-specific data (SD7), refer to the User's Guide
(Chapter 2).
-------
SOURCE DATASHEET - TANKS (continued)
240
PARAMETER
INSTRUCTIONS*
VALUE
CONTAMINANT PARAMETERS
SD7 Contaminant Data
Use Contaminant Forms S.I or S.2 to complete
the Contaminant Data Table below. Refer
to Task 2 of the User's Guide for additional
guidance.
Contaminant Data Table
1
2
3
Contaminant/Mixture
Score
Toxicity
Score
Concentration
Score
Mobility
Score
Persistence
Score
* For additional guidance, especially for contaminant-specific data (SD5), refer to the User's Guide.
(Chapter 2).
-------
241
SOURCE WORKSHEET
TANKS
-------
242
Step 6
SOURCE #
SOURCE WORKSHEET - TANKS
STEP
INSTRUCTIONS
SCORE
LIKELIHOOD OF RELEASE (LJ
Step 1 Likelihood of Release (La) Score
Use the graphs on the next page to determine the
Likelihood of Release Score (L,) as a function
of Tank Design (SD3) and Tank Age (SD4). For
Designs 1-3, use the first graph; for Designs 4-7,
use the second graph; for Designs 8-10, use the
third graph; and for Designs 11-12, use the fourth
graph. Note that if your Tank Design is 3 or 10,
L! = 0. If Tank Age is greater than 40 years, set
the Likelihood of Release Score to 0.
Likelihood of Release (Li) Score =
(Ref. 25)
GRAPH 1: DESIGNS 1-3
UKEUHOOO OF RELEASE SCORE FOR ABOVE-GROUND AND IN-GROUND STORAGE TANKS
0.0
•0.2
•0.4
-0.6
•0.8
-1.0
•1.2
-1.4'
-1.6'
-1.8'
•iO
•22-
•2.4 •
D«sign3
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 30 38 40
TmkAg»(YMi»)
-------
243
SOURCE WORKSHEET - TANKS (continued)
STEP
INSTRUCTIONS
SCORE
I
•
I
"a
I
•5
•5
1
GRAPH2: DESIGNS4-7
UKEUHOOD OF RELEASE SCORE FOR BELOW-GROUND STORAGE TANKS
101214 16 18 20 22 24 26 28 30 32 34 36 38 40
TankAg«(Y<
GRAPH 3: DESIGNS 8-10
UKEUHOOD OF RELEASE SCORE FOR TREATMENT TANKS
2 4 8 I) 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Tank Ag* (Yaars)
GRAPH 4: DESIGNS 11 .12
UKEUHOOO OF RELEASE SCORE FOR SQG AND FARM STORAGE TANKS
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
-------
SOURCE WORKSHEET - TANKS (continued)
"•'«'£-
.-fl--;w
•••'•'!*,.
244
STEP
INSTRUCTIONS
SCORE
QUANTITY (Q)
Step 2 Compute the Volume Score
Use the graph below to determine
the Volume Score as a function of
the Number of Tanks (SD1), Tank Size
(SD2), and Tank Design (SD3).
Volume Score for Storage and Treatment Tanks
Tank
Deiign
1
2
3
4
5
6
7
8
9
10
11
12
* f JtfA '"fr f f "• j ••••
• ' Number of Tanks , •• •>
1
Tint Size
S
•0.2
-
-0.7
' 03
-1.2
0.9
0.4
-1
-
-0.1
-0.7
-1.3
M
-0.1
-
-0.6
0.4
-1
1
0.5
-0.8
-
-0.1
-
-
L
-
0.9
-0.4
-
-
-
0.6
-
0.2
0.1
-
-
2-5
Tank Size
S
0.2
-
-0.2
0.7
-0.7
1.4
0.9
-0.5
-
0.3
-03
-0.9
M
0.3
-
-0.1
0.8
-0.5
1.5
1
-0.3
-
-0.3
-
-
L
-
1.3
0.1
-
-
-
1.1
-
0.7
0.5
-
-
6-25
Tank Size ' r
S
1.4
-
1
1.9
0.5
2.6
2.1
0.7
-
1.5
0.9
0.9
M
1.5
-
1.1
2
0.7
2.7
2.2
0.9
-
1.5
-
-
L
-
2.5
1.3
-
-
-
2.3
-
1.9
1.7
-
-
26-75
Tank Size
S
1.9
-
1.5
2.4
1
3.1
2.6
1.2
-
2
1.4
0.8
M
2
-
1.6
2.5
1.2
.3.2
2.7
1.4
-
2
-
-
L
-
3
1.8
-
-
-
2.8
-
2.4
2.2
-
-
>75
Tank. Size
S
2.2
-
1.8
2.7
1.3
3.4
2.9
1.5
-
2.3
1.7
1.1
M
2.3
-
1.9
2.8
1.5
3.5
3
1.7
-
2.3
-
-
L
-
3.3
2.1
-
-
-
3.1
-
2.7
2.5
-
-
— Indicates not applicable
S = Small, M = Medium, L = Large
Volume Score:
(Ref. 25)
-------
245
SOURCE WORKSHEET - TANKS (continued)
STEP INSTRUCTIONS SCORE
StepS Compute the Quantity Score (Q) for Each Contaminant
Quantity Score (Q) = Concentration Score (SD7)
+ Volume Score (Step 2)
Contaminant or Contaminant Mixture Quantity Score (Q)
(1) ___^_
(2)
(3)
-------
-------
TRANSPORT WORKSHEET
STEP; INSTRUCTIONS SCORE
This worksheet* provides guidance for determining scores for each step in the transport
calculations. In this guidance, the labels in parentheses refer to three sources of scores:
> scores from a step in the Wellhead Datasheet, e.g., (WD2)
>• scores from the Source Datasheet, i.e., (SD)
>• scores from a step in this Transport Worksheet, e.g., (Step 5).
Step 1 Compute Timeframe
Timeframe (years) = Age of Source (SD)
+ Planning Period (WD1)
Timeframe = _
CONTAMINANT-SPECIFIC STEPS
Steps 2 through 8 will help you calculate two risk elements for each contaminant or
contaminant/mixture at the source: Likelihood of Reaching the Well (Lj) and Attenuation Due to
Transport (A). For a given source, Lj and A vary only with the contaminant's mobility and
persistence. Therefore, you need only recompute Lj and A by completing Steps 2 through 8 for
contaminants with different values of mobility and/or persistence.
Step 2 Determine Hydraulic Conductivity and Velocity Scores
Use the following table to determine the Hydraulic
Conductivity and Velocity Scores as a function of
the Contaminant Mobility (SD) and either the
Unsaturated Zone Hydraulic Conductivity score
(WDS) or the Ground-Water Velocity score (WD7),
respectively. For example, if Contaminant Mobility
is Medium and the Unsaturated Zone Hydraulic
Conductivity score is 4, then the Hydraulic
Conductivity Score is equal to 3.
References 17, 43, 57, and 73 were used to develop this worksheet.
-------
TRANSPORT WORKSHEET (continued)
248
STEP
INSTRUCTIONS
SCORE
Adjusted Hydraulic Conductivity and Velocity Scores
Unsaturated Zone
Hydraulic Conductivity
Score or Ground-Water
Velocity Score
1
2
3
4
5
Contaminant Mobility
L
1
1
- 1
2
3
M
1
1
2
3
4 -
H
1
2
3
4
5
Hydraulic Conductivity Score =
Velocity Score =
CONTAMINANT
1 23
Quick Exit
If the source discharges directly to a conduit
system that could transport contaminants directly
to the well (SD), then for each contaminant
at the source:
Skip Steps 3 and 4, set the Likelihood of
Reaching the Well (Lj) in Step 5 equal to 0,
and go to Step 6.
-------
249
TRANSPORT WORKSHEET (continued)
STEP
INSTRUCTIONS
SCORE
Step 3 Determine Unsaturated Zone and Saturated Zone Time of Travel (TOT) Categories
Use the following table to determine
the Unsaturated Zone TOT Category as a
function of the Depth to Aquifer score (WD2)
and die Hydraulic Conductivity score (Step 2).
For example, if the Depth to Aquifer score is
1.5 and the Hydraulic Conductivity Score' is 2,
then the Unsaturated Zone TOT Category is D.
Unsaturated Zone Time of Travel Category
Depth to
Aquifer
Score
0.3
1
1.5
2.2
Hydraulic Conductivity Score
1
E
F
F
F
2
B
C
D
D
3
A
A
B
B
4
A
A
A
A
5
A
A
A
A
Unsaturated Zone TOT Category =
CONTAMINANT
1 2 3
-------
TRANSPORT WORKSHEET (continued)
250
STEP
INSTRUCTIONS
SCORE
Likewise, use the following table to determine
the Saturated Zone TOT Category as a function
of the Distance score (SD) and Velocity Score
(Step 2).
Saturated Zone Time of Travel Categories
Distance
Score
1
2
3
4
5
6
Velocity Score
2
D
D
E
F
F
F
3
B
B
B
C
C
C
4
A
A
A
A
A
A
5
A
A
A
A
A
A
Note: If the Velocity Score is 1, then the Saturated Zone Time of Travel
Category is Equal to F
CONTAMINANT
12 3
Saturated Zone TOT Category =
-------
TRANSPORT WORKSHEET (continued)
251
STEP
INSTRUCTIONS
SCORE
Step 4 Determine Unsaturated Zone and Saturated Zone Likelihoods (L^) and
Use the following table to find the
Unsaturated Zone Likelihood (Lu) as
a function of the Unsaturated Zone TOT
Category (Step 3) and Timeframe (Step 1).
Unsaturated and Saturated Zone Likelihood Scores (L^ and
Time of
Travel
Category
A
B
C
D
E
F
Timeframe (Years)
1-10
0
••0.3
-3
-100
-100
-100
11-100
0
0
-0.3
-0.9
-100
-100
101-500
0
0
-0.1
-0.3
-0.3
-100
501-1000
0
0
0
-0.1
-0.3
-100
Unsaturated Zone Likelihood
CONTAMINANT
1 .2 3
Use the same table to determine the Saturated
Zone Likelihood (Ls) as a function of the
Saturated Zone TOT Category (Step 3) and
Timeframe (Step 1).
Saturated Zone Likelihood (Ls) =
-------
252
TRANSPORT WORKSHEET (continued)
STEP INSTRUCTIONS SCORE
Step 5 Compute Likelihood of Reaching the Well (L,)
Set
LZ = LU (Step 4) + Ls (Step 4)
Note: As the Likelihood of Reaching the Well
(Lj) score becomes very low (i.e., less than
-10), the estimated risk approaches a negligible
value.
CONTAMINANT
1 23
Likelihood of Reaching the Well (LJ =
Step 6 Determine Unsaturated Zone Attenuation (A^
Use the following table to determine the Unsaturated
Zone Attenuation (A0) as a function of the Depth to
Aquifer score (WD2), the Hydraulic Conductivity score
(Step 2), and Contaminant Persistence (SD). For
example, if the Depth to Aquifer Score is 1.5, the ,
Hydraulic Conductivity score is 2, and the Contaminant
Persistence is High, then the Unsaturated Zone Attenuation (Au)
is equal to 0.
-------
TRANSPORT WORKSHEET (continued)
253
STEP
INSTRUCTIONS
SCORE
Unsaturated Zone Attenuation Scores (A,,)
Hydraulic
Conductivity
Score
1
2
3
4
Contaminant
Persistence
L
M
H
L
M
H
L
M
H
L
M
H
Depth to Aquifer Score
0.3
-100
-6
-0.2
-100
-0.1
0
-0.2
0
0
0
0
0
1.0
-100
-31.2
-1.2
-100
-0.3
0
-1.2
0
0
0
0
o
1.5
-100
-94.8
-3.6
-100
-0.9
0
-3.6
0
0
0
0
0
2.2
-100
-100
-12.0
-100
-3.1
-0. 1
-12.0
0
0
-0.1
0
0
Note: If the Hydraulic Conductivity Score is 5, then Av is equal to 0 (regardless of the
contaminant persistence and depth to aquifer scores).
CONTAMINANT
1 2 3
Unsaturated Zone Attenuation (Aw) =
-------
254
TRANSPORT WORKSHEET (continued)
STEP INSTRUCTIONS SCORE
Step 7 Compute Saturated Zone Attenuation (As)
Use the table on the next page to determine the
Unadjusted score as a function of the Saturated
Zone Material (WD6), the Distance score (SD),
the Velocity score (Step 2), and Contaminant
Persistence (SD). For example, if the Saturated
Zone Material is Sand, the Design score is 2, the
Velocity score is 3, and the Contaminant Persistence
is High, then the Unadjusted score is equal to -0.6.
Then set
As = Unadjusted score (from table)
- Aquifer Thickness score (WD3).
You must subtract the Aquifer Thickness score from the
Unadjusted score to determine A8.
CONTAMINANT
123
Saturated Zone Attenuation (As) =
Step 8 Compute Attenuation Due to Transport (A)
Set
A = AU (Step 6) + As (Step 7).
Note: Low values of the Attenuation Due to
Transport score (A) generally cause the Potential
Severity of Well Contamination to be relatively
small. For a value less than -1.0, the potential
Severity of Well Contamination
generally is negligible.
CONTAMINANT
1 2 3
Attenuation due to Transport (A) =
-------
255
Unadjusted Saturated Zone Attenuation Scores
Saturated Zone Material
SILT
SAND
GRAVEL
KARST
vs
CP
Distance Score
1
Distance Score
1
Distance Score
1
Distance Score
1
L
M
H
-100 -100 -100 -100 -100 -100
-2.0 -10.0 -22.0 -45.8 -100 -100
1.8 1.3 0.7 -0.3 -3.3 -8.0
-100 -100 -100 -100 -100 -100
-2.3 -10.2 -22.3 -46.1 -100 -100
1.6 0.9 0.4 -0.7 -3.7 -8.3
-100 -100 -100 -100 -100 -100
-2.7 -10.6 -22.6 -46.4 -100 -100
1.2 0.6 0.0 -1.0 -4.0 -8.7
-100 -100 -100 -100 -100 -100
-3.8 -11.9-23.9 -47.7-100 -100
0.0 -0.5 -1.1 -2.1 -8.1 -9.8
L
M
H
-15.1 -45.7 -91.5 -100 -100 -100
0.0 -0.3 -0.6 -1.0 -1.9 -3.3
0.0 -0.2 -0.4 -0.5 -0.8 -1.0
-15.4 -46.0 -91.8 -100 -100 -100
-0.3 -0.7 -0.9 -1.4 -2.3 -3.6
-0.3 -0.6 -0.7 -0.9 -1.2 -1.3
-15.7 -46.3 -92.6 -100 -100 -100
-0.7 -1.0 -1.3 -1.7 -2.6 -4.0
-0.7 -0.9 -1.1 -1.2 -1.5 -1.7
-1.8 -15.0-47.6 -93.4-100 -100
-1.8 -2.1 -2.4 -2.8 -3.7 -5.1
-1.8 -2.0 -2.2 -2.3 -2.6 -2.8
L
M
H
-2.1 -2.7 -3.3 -4.3 -7.3 -11.9
-2.0 -2.2 -2.4 -2.5 -2.7 -2.9
-2.0 -2.2 -2.4 -2.5 -2.7 -2.9
-2.3 -3.1 -3.6 -4.7 -7.7 -12.2
-2.3 -2.6 -2.7 -2.9 -3.1 -3.2
-2.3 -2.6 -2.7 -2.9 -3.1 -3.2
-2.7 -3.4 -4.0 -5.0 -8.0 -12.5
-2.7 -2.9 -3.1 -3.2 -3.4 -3.6
-2.7 -2.9 -3.1 -3.2 -3.4 -3.6
-3.8 -4.5 -5.1 -8.1 -891 -13.7
-3.8 -4.0 -4.2 -4.3 -4.5 -4.7
-3.8 -4.0 -4.2 -4.3 -4.5 -4.7
L
M
H
-4.0 -4.2 -4.4 -4.5 -4.8 -5.0
-4.0 -4.2 -4.4 -4.5 -4.7 -4.9
-4.0 -4.2 -4.4 -4.5 -4.7 -4.9
-4.3 -4.5 -4.7 -4.9 -5.2 -5.3
-4.3 -4.6 -4.7 -4.9 -5.1 -5.2
-4.3 -4.6 -4.7 -4.9 -5.1 -5.2
-4.7 -4.9 -5.1 -5.2 -5.5 -5.7
-4.7 -4.9 -5.1 -5.2 -5.4 -5.6
-4.7 -4.9 -5.1 -5.2 -5.4 -5.6
-5.8 -6.0 -6.2 -6.3 -6.6 -6.8
-5.8 -6.0 -6.2 -6.3 -6.5 -6.7
-5.8 -60 -6.2 -6.3 -6.5 -6.7
Note: VS = Velocity Score, CP = Contaminant Persistence
If the velocity score is 1, then the Unadjusted Saturated Zone Attenuation Score is equal to -100 (regardless of contaminant persistence, saturated
zone material and distance score).
-------
-------
257
TECHNICAL APPENDIX A:
ASSUMPTIONS AND LIMITATIONS OF THE
PRIORITY SETTING APPROACH
The Priority Setting Approach incorporates many assumptions. This appendix
discusses the major assumptions regarding aquifer physical properties, zone of contribution,
potential contamination sources, toxicity of contaminants or contaminant mixtures, and dense
and light non-aqueous phase liquids. It also provides a summary of the effects on the risk
scores if these assumptions vary from actual field settings.
Aquifer Physical Properties
The theoretical basis of this Approach's transport component includes two elements:
(1) the Darcy flow law to describe the movement of contaminants from the source to the .aquifer,
in the unsaturated zone and (2) an analytical two-dimensional transport model (developed by
Wilson and Miller) to describe the movement of contaminairts in the saturated zone from
directly below the source to the wellhead.
Several basic hydrogeologic settings can be reasonably evaluated using the Priority
Setting Approach, as presented in Exhibit A-l. In Setting 1, contamination from the source is
released into an unconfined (water table) aquifer and is intercepted by a well in the same
aquifer. In Setting 2, contamination results from the failure in a confined aquifer of the casing
of a Class I, II, or III injection well. This contamination .is then intercepted by a well drawing .,
water from the same confined aquifer. Setting 3 involves a contamination source in a recharge
zone for a confined aquifer that is in direct hydraulic connection with the ground surface. This
situation occurs if the confining.layer is relatively thin or absent in the recharge zone. In
Setting 4, the aquifer is overlain by a fine-grained clay that serves as a confining layer. In
wells that penetrate the confining layer into the aquifer, the water level rises above the aquifer.
This water level reflects the potentiometric surface of the aquifer. In this case, users should be
careful to use the distance from the source to the top of the confined aquifer, and not to the
potentiometric surface, as the depth to aquifer when completing the Wellhead Datasheet.
This Approach is designed to evaluate potential sources of contamination in a single
aquifer-single well system. To evaluate a composite hydrogeologic setting using this Approach,
each aquifer and its associated contamination sources must be considered separately.
-------
Exhibit A-l
258
Hydrogeologic Settings that Can Be .
Evaluated with the Priority Setting Approach
Setting 1. Surface Contamination Source-
Unconfined (Water Table) Aquifer
Setting!. Deep Source-
Confined Aquifer
/11 /1111111111111
Illlllllllll/lltl
Settings. Surface
Source in Recharge
Area- Confined Aquifer
cxx/xxxxxxxx/x./'y
Setting 4. Surface Source-
Confined Aquifer.
/11 //'/"/ n /1 n ///
7/777/////
-------
ASSUMPTIONS AND LIMITATIONS OF THE PRIORITY SETTING APPROACH 259
This Approach assumes homogeneity and isotropy of the hydrogeologic system within the
WHPA. In particular, it assumes that the hydrogeologic parameters are uniform throughout the
WHPA,1 that uniform and steady flow prevails, and that the aquifer is of infinite extent. This
implies that the thickness and flow rate in the unsaturated and saturated zones are constant.
Moreover, the flow velocity in the aquifer is assumed to reflect both the effects of the regional
hydraulic gradient and pumping stresses, and is set to an average constant for the entire
WHPA.
This Approach provides default hydraulic conductivity values as a function of the type
of material (e.g., sand or clay); these defaults do not vary between the saturated and
unsaturated zones. Default flow velocities are based upon a unit hydraulic gradient and an
average porosity of 0.3. This requires mat the effect of drawdown near the well in an
unconfmed aquifer be relatively small compared to the saturated thickness. Consequently, it is
assumed that pumping rates are not so excessive so as to completely dewater even a fine-
grained aquifer. If the user does not know the pumping rate hi an aquifer consisting primarily
of sand, then he or she should select the appropriate ground-water velocity score from Table
W.4. Finally, it is assumed that wells fully penetrate the aquifer.
Zone of Contribution
WHPAs can be delineated using a variety of techniques ranging from simple, somewhat
arbitrary graphical techniques to complicated methods based upon analytic or numerical
modeling. In practice, the WHPA boundary may coincide with a ground-water divide,
lithologic boundary, or even a jurisdictional border. This Approach assumes that the
boundaries of a WHPA are contained within the zone of contribution, as described hi the Office
of Ground Water and Drinking Water's "Delineation of Wellhead Protection Areas. ?.-
Depending on how the WHPA has been delineated, there may exist contamination sources in
the zone of contribution that are not located inside the WHPA. If you know of such sources,
you may want to evaluate them In addition to sources located inside the WHPA.
The Darcy flow law and Wilson and Miller model consider the following major parameters: vertical
distance from the contamination source to the top of the aquifer, unsaturated hydraulic conductivity,
longitudinal distance from the contamination source to the wellhead, aquifer flow velocity, porosity, and
transverse dispersivity (a measure of how fast contamination spreads in the direction perpendicular to the
prevailing ground-water direction).
-------
ASSUMPTIONS AND LIMITATIONS OF THE PRIORITY SETTING APPROACH 2m
Contamination Sources
The Priority Setting Approach also makes assumptions about the physical and chemical
. characteristics of the sources of potential contamination. For example, it is assumed that the
contamination is in the form of an aqueous solution having the same density and viscosity as
water. It is further assumed that constituent concentrations do not vary with time. The
transport model considers each source as a point source and assumes that concentrations do not
vary in the vertical dimension. Retardation coefficients and biodegradation rates are also
assumed to be constants that are not affected by concentration or by mixture with other
constituents. Leakage from a contamination source is assumed to influence neither the shape of
the water table nor the prevailing ground-water velocity. Finally, this Approach assumes that
the contamination at the wellhead is not diluted from capture of "clean water" during pumping.
Toxicity of the Contaminant • •
Toxicity of the contaminant indicates the potential health hazard posed by ingesting the -
contaminant. The Toxicity scores are based on established dose-response relationships obtained
from EPA's Integrated Risk Information System (IRIS) or from the RASH database (only for a
few contaminants). Using these dose-response relationships, a "critical dose" is defined for
each contaminant, which represents the dose at which health risks become of concern.
Because carcinogens and non-carcinogens act differently on the body, the critical dose
is defined differently for each of them (note that the Priority Setting Approach does not address
microbiological contaminants). For non-carcinogens, the critical dose is defined as the EPA-
defined oral reference dose (RfD), which is the threshold exposure level at which health effects
begin to occur. For carcinogens, it is generally assumed that no threshold levels exist because
any level can cause cancer. Therefore, for carcinogens, the critical dose is defined as the dose
that increases the risk of cancer by 10"5 over background levels; i.e., an excess cancer risk of 1
in 100,000. This Approach converts these critical doses into critical concentrations (in
milligrams per liter of drinking water) using standard Office of Ground Water and Drinking
Water assumptions (i.e., two liters consumed per day over a 70-year lifetime exposure period).
Toxicity of the contaminant is defined as the decimal logarithm of the inverse of the
critical concentration in mg/1. Thus, the Toxicity Score T has units of Iog10(l/(mg/l)). You
read the Toxicity score T directly from a concentration scoring graph (end of Form S.I) or a
table (Form S.2).
Because the health risks posed by carcinogens and non-carcinogens are very different,
as are the methods used to. define these risks, many users may prefer to track mem separately.
If you choose to produce only one screening and ranking of all .sources, then you can consider
both carcinogens and non-carcinogens together. In this case, the Priority Setting Approach has
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ASSUMPTIONS AND LIMITATIONS OF THE PRIORITY SETTING APPROACH 261
a built-in formula for comparing carcinogenic and non-carcinogenic risks. As discussed
previously, this Approach implicitly equates a 10"5 lifetime cancer risk to a lifetime exposure to
the reference dose (RfD) for non-carcinogens. You can alter this assumption to reflect different
policy calls. For example, you can choose to equate a 10"6 lifetime cancer risk to a lifetime
exposure to the reference dose (RfD) for non-carcinogens, In this case, you should add a 1 to
all the risk scores for carcinogenic contaminants as computed in Task V, Step 1. If you choose
to equate a 10"4 lifetime cancer risk to a lifetime exposure to the reference dose (RfD) for non-
carcinogens, then you should subtract a 1 from all the risk scores for carcinogenic
contaminants.
Dense and Light Non-Aqueous Phase Liquids (DNAPLs and LNAPLs)
Dense non-aqueous phase liquids (DNAPLs), also known as sinkers, and light non-.
aqueous phase liquids (LNAPLs), also known as floaters, are ground-water contaminants that
are relatively insoluble in water and have densities greater than and less than water,
respectively. Due to their density and limited solubility hi water, DNAPLs and LNAPLs can
pose special risks to ground-water quality. If released in large quantities, these liquids can ~; ;
migrate vertically under the influence of gravity (i.e., sink to the bottom of the saturated zone if
a DNAPL or float on the water table if an LNAPL) and act as a highly concentrated, long-term
source of contamination.
The Priority Setting Approach allows you to recognize DNAPLs and LNAPLs in two
stages. First, contaminant Form S.I notes those contaminants that are potential DNAPLs or
LNAPLs (see Task II, Step 5). Second, this Approach provides a rule of thumb for
determining whether a potential DNAPL or LNAPL will act as a true DNAPL or LNAPL
based on the quantity of the contaminant released. Specifically, a potential DNAPL or LNAPL.
will act as a true DNAPL or LNAPL if the Quantity score for that contaminant is greater than
or equal to 3; that is, if the contaminant is released at an annual rate of 1,000 kg per year or
more (see Task III, Step 6).
The Transport Worksheet does not model the fate and transport phenomena specific to
DNAPLs and LNAPLs. These liquids follow different transport patterns from other common
contaminants because they are denser or lighter and more or less viscous than water. As a
result, they tend to sink to the impervious base.of the saturated zone (for DNAPLs) or float on
top of the water table (for LNAPLs). For example, because DNAPLs tend to move along
impervious layers of soils or rock, they will move away from a drinking water well if the
impervious layer is tilted away from the well. In this case, the Priority Setting Approach will
overestimate the risk posed by a DNAPL. Because of the complexity of the transport
phenomena involved, however, this Approach does not provide guidance on whether the Risk
scores will be over-estimated or under-estimated in the case of DNAPLs or LNAPLs.
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ASSUMPTIONS AND LIMITATIONS OF THE PRIORITY SETTING APPROACH 262
Therefore, this Approach does not apply to potential DNAPLs or LNAPLs with a Quantity
score of 3 or more.
NOTE: DNAPLS and LNAPLs can be a serious threat to wellheads and are extremely
difficult to remove from the water supply once contamination occurs. If you believe a DNAPL
or LNAPL is present in the water supply or threatens a wellhead, you should pay special
consideration to this threat.
Validity of the Risk Estimates Under Field Conditions that Diverge from the Priority
Setting Approach Assumptions
Exhibit A-2 presents a summary explanation of the effects on the accuracy of the Risk
scores if you diverge from the assumptions summarized hi this appendix. The first column lists
field conditions that differ from the conditions assumed in this Approach. The second column
notes the effects on the risk estimates as a result of diverging from the model conditions.
For example, this Approach assumes that contaminants flow in a straight line between a
source and a well. If a source is not directly upgradient, the contaminant flow path will most
likely not be a straight line. In this Approach, such sources are called "off-center" sources.
The Priority Setting Approach over-estimates the risks posed by an off-center source because it
underestimates the travel time of the contaminants from such sources. Note that in some
instances, it is not possible to say whether the Priority Setting Approach will overestimate or
underestimate risks. For example, for DNAPLs or LNAPLs, it may overestimate or
underestimate risks depending on a number of factors not modeled in this Approach (see the
discussion above on DNAPLs and LNAPLs).
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ASSUMPTIONS AND LIMITATIONS OF THE PRIORITY SETTING APPROACH 263
Exhibit A-2
Validity of the Risk Estimates Under
Field Conditions that Diverge from the Priority Setting Approach's Assumptions
Field Condition
Effect of Field Condition Upon Accuracy
of Risk Estimate
Non-uniform aquifer thickness
Spike release at source
Seasonal pumping cycle
Areal source
Dense non-aqueous phase liquids
(DNAPLs)
Light non-aqueous phase liquids
(LNAPLs)
Partial penetration of well
Contaminant dispersion in
unsaturated zone
Dilution at wellhead
Off-center source
Anisotropy
Overestimate/Underestimate - depends on downgradient
trend
Overestimate/Underestimate - depends on distance to
source and flow velocity
Overestimate
Overestimate/Underestimate - depends on relative
proximity of source to wellhead
Overestimate/Underestimate - depends on density,
viscosity, quantity, and surface tension of contaminant
Overestimate/Underestimate - depends on density,
viscosity, quantity, and surface tension of contaminant
Overestimate
Overestimate
Overestimate
Overestimate
Overestimate/Underestimate - depends on relative
position of source and well
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265
TECHNICAL APPENDIX B:
CONCEPTUAL OVERVIEW OF THE
PRIORITY SETTING APPROACH
The Priority Setting Approach is a simple tool that allows the manager of a WHPA to assess
the risks posed by potential sources of wellhead contamination. This appendix presents a general
overview of the Approach's framework, describes the two components of risk in this Approach, and
reviews how risk is computed as a function of these two risk components.
Overview of the Priority Setting Approach's Framework
The Priority Setting Approach is applied through a set of step-by-step worksheets. The user 4s*
led through a series of simple computations to calculate the risk posed by each potential
contamination source within a WHPA. This section describes how this Approach emulates a human
health risk assessment using simple, yet meaningful additive risk scores.
The Priority Setting Approach Emulates,, a Conventional Human Health Risk Assessment
The Priority Setting Approaich is based on a simplified version of a conventional human health
risk assessment. A conventional human health risk assessment generally answers two basic
questions: (1) what is the frequency/duration of the exposure to a substance? and (2) what is the
degree of toxicity of the substance? For the purposes of this Approach, the exposure and toxicity
coefficients equate to: (1) What is the probability that something will go wrong?.and (2) What are
the consequences in the event something does go wrong?
This Approach considers two components of risk. For a given contaminant or contaminant
mixture present at a potential contamination source, the user estimates a Risk score as the sum of
two risk components:
(1) Likelihood of well contamination; that is, the likelihood that the contaminant
will be released from that source and will reach the well within a specified
period of tune.
(2) Severity of well contamination; that is, the potential health hazard from
drinking water drawn from the well that has been polluted by that
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CONCEPTUAL OVERVIEW OF THE PRIORITY SETTING APPROACH 266
contaminant, taking into account contaminant dilution and dispersion between
the source and the wellhead.
The Overall Risk score for a given source of potential contamination is the highest of the Risk
scores'associated with each contaminant or'contaminant mixture present at the source.
Scoring Is Based on Logarithmic Conversion of Natural Units
The algorithms used in this Approach reflect the "natural units" of each risk parameter. For
example, contaminant releases are expressed as mass released per unit of time (kg/yr), while
contaminant concentrations are measured as mass unit per unit volume of water (kg/m3). In
addition, the risk parameters are functionally related within this Approach hi the same manner that
they are in a conventional human health risk assessment. The reliance on natural units of
measurement and natural functional relationships ensures that the scores are non-arbitrary. That is,
each variable is assigned its natural "weight" in terms of its contribution to the final Risk score.
The functional products of a conventional risk assessment are generally derived by multiplying
several individual parameters to determine risk assessments. To ensure relative ease of use of this '
Approach without compromising on the rigor of a conventional risk assessment, the Priority Setting
Approach assumes a conversion of the basic product (derived risk values) using the decimal
logarithmic function. As a result, individual parameters generally are summed rather than
multiplied to obtain risk scores.
The implicit use of decimal logarithmic conversion is best illustrated by the following example.
The quantity of contaminant released annually (in kg/yr) is equal to the product of the volume of
"waste" released annually (in m3/yr = 1,000 1/yr) times the contaminant concentration in waste (in
kg/m3 = 1,000 ppm = 1,000 mg/1). Using the decimal logarithmic conversion, the Quantity score
flog10(kg/yr)) is computed as the sum of the Volume score (Iog10(m3/yr)) plus the Concentration
score (in logwOcg/m3)). That is, if 1 million liters of a solution containing benzene at a
concentration of 1,000 ppm are released annually, then the Quantity score is equal to 3: i.e., 3 for
the Volume score (i.e., Iog10(l,000 m3/yr)) plus 0 for the Concentration score (i.e., Iog10(lkg/m3)),
which means that 1,000 kilograms of benzene are released annually).
Likelihood of Well Contamination
Likelihood of well contamination gives the probability that a source contaminant will reach the
well within a user-specified time horizon, referred to as the Planning Period. As described hi this
section, for a given contaminant or contaminant mixture at a given source of potential
contamination, Likelihood of well contamination is the sum of two partial risk scores: the
Likelihood of release at the source and the Likelihood that the contaminant will reach the well.
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CONCEPTUAL OVERVIEW OF THE PRIORITY SETTING APPROACH 267
Likelihood of Release at the Source (L,)
Likelihood of release at the source (L,) reflects the likelihood of an average-sized release of a
contaminant from a source. Lt is a function of the source type and is based on engineering failure
analyses that account for the type of potential contamination source (e.g., landfills versus tanks) It
is also a function of design characteristics (e.g., number and type of liners at a landfill) and
operating status (e.g., age), as appropriate. For example, the Lt values for tanks are a function of
tank design (one of 12 designs hi the Priority Setting Approach) and tank age, and are derived from
the Hazardous Tank Failure Model (ref. 12).
To derive the 1^ score, refer to the tables hi the Source Worksheets, which provide the 1^
score as a function of input parameters such as the age, design, and status of a specific source.
Higher values of Lj indicate a greater likelihood of release. For example, an L! score of 0
corresponds to a probability of 1 (i.e., 100 percent chance of release), while an 1^ score of -3.5
corresponds to a lower probability of 0.0032.
Likelihood that the Contarainant Released Will Reach the Well
This partial risk score reflects the probability that the contaminant will reach the well within
the Planning Period, assuming that the contaminant is released from the source starting from day
one in the source's lifetime. The Transport Worksheet derives the Likelihood of reaching the well
(Lj) by comparing (1) the time of travel of the contaminant from the source to the well, to (2) the
sum of the source age plus the Planning Period. '
For simplification, the L, score is approximated as the sum of two scores: L0 for the
unsaturated zone and Ls for the saturated zone. The LU score is based on the tune of travel of the
contaminant through the unsaturated zone in comparison to the Planning Period. Likewise, the LS
score is based on the time of travel through the saturated zone to the well hi comparison to'the
Planning Period.
For a given contaminant, the time of travel through the unsaturated zone (TOTu) is given by
Darcy's law as a function of the depth to the aquifer, the hydraulic conductivity of the unsaturated
zone, and the contaminant mobility. If all parameters could be estimated with precision, the
question "will the released contaminant cross the unsaturated zone within the Planning Period?"
could be answered simply "yes" or "no." That is, the probability that the contaminant will cross the
unsaturated zone within the Planning Period is either zero (i.e., LU = -oo) if TOTu is less than the
Planning Period, or one (i.e., LU = 0) if TOTu is greater than or equal to the Planning Period. In
this Approach, however, input parameters are estimated within ranges, and functional relationships
are only approximations of the fate and transport phenomena taking place. Due to this uncertainty,
this Approach computes a probability that is between zero and one, that is, a likelihood L0 that is '
between -oo and 0.
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• '•f,
CONCEPTUAL OVERVIEW OF THE PRIORITY SETTING APPROACH 26S
Likewise, for a given contaminant, the tune of travel through the saturated zone (TOTS) is a
function of the distance from the source to the well, ground-water velocity, and the contaminant
mobility. Because of the uncertainty and variability of these input parameters and, therefore, of the
functional relationship to compute TOTS, this Approach computes a probability between zero and
one (i.e., likelihood Lg between -co and 0) that the contaminant will cross the saturated zone to the
well within the Planning Period.
You read the values of LU and LS from tables as a function of the above-mentioned input
parameters. Then compute the Likelihood that the contaminant will reach the well (Lj) by summing
LU and LS. Bypass the calculations of LU and Ls and set the L, score equal to 0 if the source
discharges directly to a conduit system (e.g., abandoned utility network) that provides a short-cut to
the well for the released contaminant. L, values are less than or equal to 0, with higher values
(approaching zero) indicating higher probabilities that the contaminant will reach the well if
released.
Deriving the Likelihood of Well Contamination (L)
For a given contaminant present at a given source, the well will be contaminated within the'
Planning Period if and only if the contaminant is released from the source and reaches the well
within the Planning Period. Thus, the probability of well contamination is equal to the probability
of release from the source multiplied by the probability that the contaminant will reach the well
within the Planning Period. Talcing the decimal logarithm of these probabilities, the Likelihood of
well contamination (L) is the sum of the Likelihood of release of the contaminant at the source (L,)
plus the Likelihood that the contaminant will reach the well within the planning period (Lj):
Likelihood of well = Likelihood of + Likelihood of reaching
contamination score (L) release score (Lt) the well score
The Likelihood of well contamination (L) is less than or equal to 0. The higher the value of L (i.e.,
the closer L is to 0), the higher the likelihood that the contaminant will be released and reach the
well within the specified Planning Period.
Severity of Well Contamination
For a given contaminant or contaminant mixture at a potential source of contamination,
Severity of well contamination (S) reflects the potential health hazard from drinking water from a
well that has been polluted by that contaminant. As discussed hi this section, Severity of well
contamination (S) is the sum of three partial risk scores: the Quantity (Q) of contaminant released
annually at the source, Attenuation (A) due to transport from the source to the well, and the
Toxicity (I) of the contaminant.
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CONCEPTUAL OVERVIEW OF THE PRIORITY SETTING APPROACH 269
Quantity Released at the Source (Q) , -
Quantity released at the source (Q) is the expected mass of contaminant or contaminant mixture
released annually from a given source of potential contamination. The expected quantity of
contaminant released annually (in kg/yr) is equal to the product of the annual expected volume of
"waste" released (m3/yr) times the contaminant concentration hi the waste (in kg/m3). Applying the
logarithmic conversion, you compute the Quantity released score (Q) (in Iog10(kg/yr)) by adding the
Volume score (represents the volume of "waste" released, in Iogw(m3/yr)) and the Concentration
score (represents the contaminant concentration hi waste, in log^^g/m3)).1
The Source Worksheets provide tables for determining the Volume score as a function of input
parameters such as facility type and size, as appropriate. You either determine the Concentration
score from a graph provided in Contaminant Form S. 1 as a function of the contaminant
concentration (if known), or read the default, contaminant-specific Concentration score applicable to
the source from Form S.2.2 The resulting scores for Q generally range from -1 to 5, with the latter
representing the largest theoretical contaminant mass release.
Attenuation Due to Transport (A)
Attenuation due to transport (A) reflects the dilution and decay of the contaminant released due
to transport from the source to the well. Attenuation is defined as the contaminant concentration at
the wellhead per unit of contaminant released annually at the source. Therefore, Attenuation due to
transport has units of Iog10((mg/l)/(kg/yr)). Note that the Attenuation score actually reflects the lack
of attenuation of the contaminant; i.e., the higher the Attenuation score, the lesser the dilution and
decay of the contaminant.
The Transport Worksheet calculates the Attenuation score (A) as the sum of two Attenuation
scores: one for the unsaturated zone, Av, and one for the saturated zone, As. The unsaturated zone
attenuation score (A0) is a function of the unsaturated zone hydraulic conductivity, the contaminant
persistence and mobility (as provided in the contaminant forms), and the depth to aquifer. It
measures the ratio of the quantity of contaminant leaving the unsaturated zone to enter the saturated
zone divided by the quantity of contaminant entering the unsaturated zone after being released from
the source. Thus, the unsaturated zone attenuation score (Au) has units of Iogi0((kg/yr)/(kg/yr));
i.e., it is dimensionless.
1 This is true for all sources except agrichemical applications, where the "Volume" score is in log,0
(hectares) and the "Concentration" score is hi Iog10 (kg/hectare/yr).
2 The Contaminant Concentration Scoring Graph in Form S.I simply converts the contaminant
concentration from kg/m3 to a Concentration score in decimal logarithm.
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CONCEPTUAL OVERVIEW OF THE PRIORITY SETTING APPROACH 270
The saturated zone Attenuation score (As) is a function of ground-water velocity, the
contaminant persistence and mobility, the type of material in the saturated zone, and the distance
from the source to the well. Using the Wilson and Miller equation to model the fate and transport
of contaminants in the saturated zone, this Approach provides the saturated zone Attenuation score
(As) inunits of log,0((mg/l)/(kg/yr)).
You derive the Attenuation score (A) by working through a series of tables that factor in the
relevant parameters described above. The resulting Attenuation score is generally less than 0, with
higher values of the Attenuation score indicating higher contaminant concentration at the well per
unit of mass released at the source. The Attenuation score thus reflects the lack of attenuation from
the source to wellhead.
Toxicity of the Contaminant (T)
Toxicity of the contaminant (T) indicates the potential health hazard posed by ingesting the
contaminant. The Toxicity scores (T) are based on established dose-response relationships obtained
from EPA's Integrated Risk Information System (IRIS) or from the RASH database (only for a few
contaminants). Using these dose-response relationships, the Priority Setting Approach defines a '
"critical dose" for each contaminant. The critical dose is defined as the oral reference dose (RfD)
for non-carcinogens and the dose corresponding to an excess lifetime risk of 10"5 (1 hi 100,000) for
carcinogens. This Approach converts these critical doses into critical concentrations (hi mg/liter of
drinking water) using standard Office of Ground Water and Drinking Water assumptions (i.e., two
liters consumed per day over a 70-year lifetime exposure period).
Toxicity of the contaminant (T) is defined as the decimal logarithm of the inverse of the critical
concentration. Thus, Toxicity (T) has units of Iog10(l/(mg/l)). You read the Toxicity score (T)
directly from a simple table (hi either Contaminant Form S.I or hi Form S.2). Toxicity scores (T)
range from -2.4 to 3.8, with higher scores (e.g., 3.8) indicating more toxic contaminants.
Deriving the Severity of Well Contamination (S)
For a given contaminant or contaminant mixture at a given source of potential contamination,
Severity of well contamination (S) is the sum of Quantity released at the source (Q), Attenuation due
to transport (A), and Toxicity of the contaminant (T):
Severity = Quantity + Attenuation + Toxicity
score (S) score (Q) score (A) score (I)
where
S is Severity of well contamination score, dimensionless
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CONCEPTUAL OVERVIEW OF THE PRIORITY SETTING APPROACH 271
™Q is Quantity released at the source, in Iog10(kg/yr) , : : ;,.
A is Attenuation due to transport, hi Iog10[(mg/l)/(kg/yr)]
T is Toxicity of the contaminant in Iog10[l/(mg/l)]. -
? >' - • •„ ' . -- . • ; •
The term (Q+A) represents the contaminant concentration at the well. Adding the term T to the
term (Q+A) is equivalent to dividing the contaminant concentration at the well by the contaminant's
critical concentration hi drinking water. Thus, the Severity of well contamination score (S)
indicates the estimated number of times the contaminant concentration at the well will vary from the
contaminant's critical concentration in drinking water. For example, a Severity of well
contamination score (S) of 0 means that the contaminant concentration at the well is estimated to be
equal to the critical concentration. If the Severity score (S) is equal to 1, the contaminant
concentration at the well is one order of magnitude (i.e., ten tunes) higher than the critical
concentration. Conversely, a Severity score (S) of -1 indicates a contaminant concentration at the
well that is one order of magnitude less than the critical concentration. The Severity scores (S)
derived from the calculations can be either negative or positive, with higher values indicating
greater contamination severity.
Risk of Well Contamination
This section describes how the Likelihood score (L) and Severity score (S) of well
contamination are combined to derive a Risk score (R) of well contamination for each contaminant
or contaminant mixture present at a given source. It then describes how the contaminant-specific
Risk scores are aggregated to derive an Overall Risk score for each potential source of
contamination. The difference between the Risk score (R) and the Overall Risk score is that the
Overall Risk score is source-specific, whereas the Risk score is contaminant-specific.
Risk of Well Contamination Posed by a Contaminant (R)
For a given source of potential contamination, the Risk of well contamination (R) posed by a
given contaminant or contaminant mixture is equal to the sum of the Likelihood of well
contamination (L) and the Severity of well contamination (S):
Risk score (R) = Likelihood score (L) + Severity score (S)
In natural units, the risk of well contamination posed by a given contaminant is the product of the
probability of well contamination, times the severity of well contamination. For example, if a
contaminant at a potential source has a Risk score of -1, then this contaminant is expected to
contaminate the well at a concentration equal to one tenth its critical concentration in drinking
water.
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CONCEPTUAL OVERVIEW OF THE PRIORITY SETTING APPROACH 272
Risk of Well Contamination Posed by a Source
The Overall Risk of well contamination posed by a given source is equal to the highest of the
Risk scores (R) of well contamination posed by individual contaminant mixtures present at the
source. For example, if a source has two contaminants A. and B with individual Risk scores equal
to -2 and -0.5, then this source has an Overall Risk score of -0.5.
You can also determine the Risk Level (i.e., Low, Medium, or High) posed by a potential
source of contamination as a function of its Overall Risk score. If the Overall Risk score is less
than -4, then the source poses a Low level of risk. If the Overall Risk score is greater than 0, then
the source poses a High risk level. If the source has an Overall Risk score between -4 and 0, then it
poses a Medium risk of well contamination. In this case, the contaminant is expected to
contaminate the well with a concentration of between 1/10,000* its critical concentration and its
critical concentration.
Plotting Contaminants and Sources on the Risk Matrix
The Risk Matrix allows you to visualize the risks posed by either individual contaminants or •
contaminant mixtures at a source or the Overall Risks posed by individual sources within the
WHPA. You will plot individual contaminants and the sources based on their Likelihood (L) and
Severity (S) scores. Sources of contamination are plotted based on the Likelihood (L) and Severity
(S) scores of the contaminant with the highest Risk score (R).
The Risk Matrix is divided into three regions corresponding to the three Risk Levels: Low,
Medium, and High. The lines separating two adjacent regions in the matrix represent equal Risk
scores (as the Likelihood score (L) goes down, the Severity score (S) goes up by an equal amount to
maintain the Risk score (Risk = L + S)).
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273
BIBLIOGRAPHY
The references cited below can provide useful information on the Source Datasheets,
Source Worksheets, Wellhead Datasheet, and Contaminant Forms. The following table points
you to references for these sheets.
Sheet
Source Datasheets and
Source Worksheets
Wellhead Datasheet
Contaminant Forms
Reference Number *
5, 8, 10-13, 16, 19-21, 25, 26,
54, 59, 63
35,37,39,41,
59
1,9,12,14,15,21-29,31-33,
54, 59-63, 70, 72
40,42,46,48-
1. Bouwer, H., "Effect of Irrigated Agriculture on Ground Water," Journal of Irrigation and
Drainage Engineering, vol. 113, no. 1, February 1987.
2. Brady, Nyle C., The Nature and Properties of Soils, 8th edition, MacMillan Publishing
Company, New York, 1974.
3. Camp Scott Furphy Pty. Ltd., Waste Disposal Facilities Hazard Assessment,
Environmental Protection Authority of Victoria, Australia, March 1985.
4. Canter, L.W. and R.C. Knox, Septic Tank System Effects on Ground Water Quality,
Lewis Publishers, Incorporated, 1985.
5. 40 CFR Parts 264.251 and 265.253.
6. 40 CFR Parts 264.280 and 265.280.
7. 70 CFR Section 144.6.
8. Clark, J.W., W. Viessman, Jr., and M.J. Hammer, Water Supply and Pollution Control,
third edition, Harper & Row, Publishers, 1977.
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BIBLIOGRAPHY 274
9. Council for Agricultural Science and Technology, Agriculture and Groundwater Quality,
report no. 103, May 1985.
10. DPRA Incorporated (formerly Pope-Reid Associates, Incorporated), Engineering Costs
Documentation for Baseline and Proposed Double Liner Rule, Leak Detection System
Rule, and CQA Program Costs for Landfills, Surface Impoundments, Waste Piles, and
Land Treatment, Office of Solid Waste, U.S. Environmental Protection Agency, March
1987.
11. DPRA Incorporated (formerly Pope-Reid Associates, Incorporated), Hazardous Waste
Land Treatment Computer Cost Model, Office of Solid Waste, U.S. Environmental
Protection Agency, March 1986.
12. DPRA Incorporated (formerly Pope-Reid Associates, Incorporated), Underground Storage
Tank Model, Office of Underground Storage Tanks, U.S. Environmental Protection
Agency, June 1987.
13. Driscoll, Fletcher G., Groundwater and Wells, 2nd edition, published by Johnson
Division, St. Paul, Minnesota, 1986.
14. Engineering Enterprises, Inc., Report of Class V Task Force on Trial Implementation of
Analytical Process: Motor Vehicle Repair and Maintenance Waste Disposal Wells,
prepared for U.S. Environmental Protection Agency, Office of Drinking Water - Class V
Injection Well Task Force, revised August 1989.
15. Environ Corporation, Characterization of Waste Streams Listed in 40 CFR Section 261,
Waste Profiles, volume I, undated. .
16. Federal Register, "Proposed Rule," May 29, 1987.
17. Fetter, C.W., Jr., Applied Hydrogeology, Charles E. Merrill Publishing Co., Columbus,
1980.
18. Freeze, R. Allen and John A. Cherry, Groundwater, Prentice Hall, New Jersey, 1979.
19. Holtz, R.D. and W.D. Kovacs, An Introduction to Geotechnical Engineering, Prentice-
Hall, Incorporated, 1981.
20. ICF Incorporated, Assessing the Releases and Costs Associated with Truck Transport of
Hazardous Wastes, Office of Solid Waste, U.S. Environmental Protection Agency, 1984.
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BIBLIOGRAPHY 275
21; IGF Incorporated (with DPRA Incorporated -formerly Pope-Reid Associates,
Incorporated), The RCRA Risk-Cost Analysis Model, Phase Iff Report, Appendices, Office
of Solid Waste, U.S. Environmental Protection Agency, January 13, 1984.
22. ICF mcoiporated (wim DPRA mcoiporated), /tegwtaoj^//^^
Disposal Restrictions of First Third Wastes, August 1988.
23. ICF Incorporated, Waste Stream Characterizations and Detailed Risk Data from the
Regulatory Impact Analysis of Restrictions on Land Disposal of California List Wastes,
February 13, 1987.
24. ICF Incorporated, Clement Associates, Incorporated, and SCS Engineering, Incorporated,
RCRA/Cost Policy Model Project Phase 2 Report, Office of Solid Waste, U.S.
Environmental Protection Agency, June 15, 1982.
25. ICF Incorporated and DPRA Incorporated (formerly Pope-Reid Associates, Incorporated),
Hazardous Waste Tanks Risk Analysis, U.S. Environmental Protection Agency, March
1986.
26. Industrial Economics, Incorporated (with DPRA Incorporated - formerly Pope-Reid
Associates, Incorporated), Region 10 Comparative Risk Project, March 4, 1988.
27. JRB Associates, Assessment of the Impacts of Industrial Discharges on Publicly Owned
Treatment Works, Office of Water Enforcement, U.S. Environmental Protection Agency,
November 1981.
28. JRB Associates, Assessment of the Impacts of Industrial Discharges on Publicly Owned -
Treatment Works, Appendices, U.S. Environmental Protection Agency, November 16,
1981.
29. Kroutch, G. Bryant, ICF Technology Incorporated, Richland, Washington, January 24,
1989 (data segment on copper leaching).
30. Leopold, L.B., Hydrology for Urban Land Planning, U.S. Geological Survey, Circular
544, 1968..
31. Lopez-Avila, V., P. Hirata, S. Kraska, M. Flanagan, J.H. Taylor, Jr., S.C. Hern, S.
Melancon, and J. Pollard, "Movement of Selected Pesticides and Herbicides through
Columns of Sandy Loam," in Garner, W.Y., R.C. Honeycutt, and H.N. Nigg, editors,
American Chemical Society Symposium Series 315, Evaluation of Pesticides in Ground
4fe Water, Miami Beach, Florida, April 28 - May 3 1985, pp. 311-327.
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BIBLIOGRAPHY 276
32. Lorber, M.N., and C.K. Offutt, "A Method for the Assessment of Ground Water
Contamination Potential: Using a Pesticide Root Zone Model (PRZM) for the Unsaturated
Zone," in Garner, W.Y., R.C. Honeycutt, and H.N. Nigg, editors, American Chemical
Society Symposium Series 315, Evaluation of Pesticides in Ground Water, Miami Beach,
Florida, April 28 - May 3 1985, pp. 342-365.
33. Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt, Handbook of Chemical Property.
Estimation Methods, McGraw-Hill Company, 1982.
, ,34. Mark's Standard Handbook for Mechanical Engineers, eighth edition, McGraw-Hill Book
Company, 1978, pp. 7-16.
35. Memorandum from Brian A. Ross, DPRA Incorporated (formerly Pope-Reid Associates,
Incorporated), to Ken Rock, ICF Incorporated, summarizing Draft Run Results of
Modeling Failures and Releases for Heap Leaching Operations, May 14,1987.
36. Metcalf & Eddy, Incorporated, Wastewater Engineering: Treatment/Disposal/Reuse,
second edition, McGraw-Hill Book Company, 1979.
37. Minnesota Pollution Control Agency, Proposed Permanent Rules Relating to Individual
Sewage Treatment Systems Design Criteria, July 28,1988.
38. RIA Mail Survey, 1982.
39. Rusin, Michael and Evi Sawides-Gellersun, The Safety of Interstate Liquid Pipelines: An
Evaluation of Present Levels and Proposals for Change, American Petroleum Institute,
research study # 040, July 1987.
40. Sax, N.I.,.editor, Hazardous Chemicals Information Annual, no. 1, Van Nostrand
Reinhold Information Services, 1986.
41. Sobotka & Company, Incorporated, Comparative Impact Analysis of Source of Ground-
Water Contamination, Phase III, Draft Report, January 29,1987.
42. Temple, Barker & Sloane, Incorporated, ICF Incorporated, DPRA Incorporated (formerly
Pope-Reid Associates, Incorporated), and America Management Systems, Incorporated,
Draft Regulatory Impact Analysis of Proposed Revisions to Subtitle D Criteria for
Municipal Solid Waste Landfills, Office of Solid Waste, U.S. Environmental Protection
Agency, August 5,1988.
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BIBLIOGRAPHY 277
43. University of Minnesota, Department of Civil Mineral Engineering, notes from a short
course entitled, "Computer Modelling of Regional Ground-Water Flow and Transport,"
undated.
44. U.S. Department of Agriculture, Results from a 1982 Pesticide Usage Survey, 1982.
45. U.S. Department of Interior, U.S. Geological Survey, Federal Glossary of Selected
Terms: Subsurface Water Flow and Solute Transport, Reston, Virginia, 1989.
46. U.S. Department of Transportation, Office of Hazardous Materials Transportation, Spill
Incident Data from the Hazardous Materials Information System, 1983-1987 data.
47. U.S. Environmental Protection Agency, Guidance for Applicants for Wellhead Protection
Program Assistance Funds Under the Safe Water Drinking Act, 1987.
48. U.S. Environmental Protection Agency, Effluent Guidelines Division, Development
Document for Effluent Limitations Guidelines and New Source Performance Standards for
the Feedlots Point Source Category, January 1974.
49. U.S. Environmental Protection Agency, Effluent Guidelines Division, Development
Document for Effluent Limitations Guidelines and Standards for the Coal Mining Point
Source Category, January 1981.
50. U.S. Environmental Protection Agency, Effluent Guidelines Division, Development
Document for Effluent Limitations Guidelines and Standards for the Inorganic Chemicals
Manufacturing Point Source Category, June 1982.
51. U.S. Environmental Protection Agency, Effluent Guidelines Division, Development
Document for Effluent Limitations Guidelines and Standards and Pretreatment Standards
for the Steam Electric Point Source Category, November 1982.
52. U.S. Environmental Protection Agency, Effluent Guidelines Division, Development
Document for Interim Final Effluent Limitations Guidelines and Proposed New Source
Performance Standards for the Photographic Processing Subcategory of the Photographic
Point Source Category, July 1987.
53. U.S. Environmental Protection Agency, Effluent Guidelines Division, Development
Document for Proposed Existing Source Pretreatment Standards for the Electroplating
Point Source Category, February 1978. ,
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BIBLIOGRAPHY 278
54. U.S. Environmental Protection Agency, Office of Drinking Water, Report to Congress on
Injection of Hazardous Waste, third printing, August 1985.
55. U.S. Environmental Protection Agency, Office of Ground Water and Drinking Water, A
Guide for Conducting Contamination Source Inventories for Public Drinking Water Supply
Protection Programs, 1991.
56. U.S. Environmental Protection Agency, Office of Ground-Water Protection, EPA
Activities Related to Sources of Ground-Water Contamination, February 1987.
57. U.S. Environmental Protection Agency, Office of Ground-Water Protection, Guidelines
for Delineation of Wellhead Protection Areas, June 22,1987.
58. U.S. Environmental Protection Agency, Office of Policy Analysis, Manual for Onsite
Wastewater Treatment and Disposal Systems, undated. '
59. U.S. Environmental Protection Agency, Office of Solid Waste, Draft Report: Liner
Location Risk and Cost Analysis Model, January 1985.
60. U.S. Environmental Protection Agency, Office of Solid Waste, Management of Hazardous
Waste Leachate, September 1982.
61. U.S. Environmental Protection Agency; Office of Solid Waste, Report to Congress on
Solid Waste from Selected Metallic Ore Processing Operations, draft report, December 14,
1987.
62. U.S. Environmental Protection Agency, Office of Solid Waste, Results from the 1987
National Survey of Hazardous Waste Treatment, Storage, Disposal and Recycling
Facilities, 1987.
63. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response,
Report to Congress: Management of Wastes from the Exploration, Development, and
Production of Crude Oil, Natural Gas, and Geothermal Energy, Volume 1 of 3, Oil and
Gas, December 1987.
64. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response,
Report to Congress: Management of Wastes from the Exploration, Development, and
Production of Crude Oil, Natural Gas, and'Geothermal Energy, Volume 2 of 3,
Geothermal Energy, December 1987.
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BIBLIOGRAPHY 279
65. U.S. Environmental Protection Agency, Office of Technology Transfer, Process Design
Manual for Nitrogen Control, October 1975.
66. U.S. Environmental Protection Agency, Office of Waste Programs Enforcement, RCRA
Ground-Water Monitoring Technical Enforcement Guidance Document, Washington
D.C., 1986.
67. U.S. Environmental Protection Agency, Office of Water Programs Operations, Evaluation
of Sludge Management Systems, February 1980.
68. U.S. Environmental Protection Agency, Underground Injection Control Branch, Office of
Water and Drinking Water, Revised Risk Assessment for Abandoned Oil and Gas Wells,
forthcoming, 1992.
69. U.S. Environmental Protection Agency, Region II, New York, Listing of Industrial
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70. U.S. Environmental Protection Agency, Water Planning Division, Results of the
Nationwide Urban Run-off Program, volume I, December1983.
71. U.S. Environmental Protection Agency and Underground Injection Practices Council,
Injection Wells: An Introduction to Their Use, Operation, and Regulation, undated.
72. Verschueren, Karel, Handbook of Environmental Data on Organic Chemicals, second
edition, Van Nostrand Reinhold Company, New York, 1983.
73. Wilson, John L. and Paul J., Miller, "Two Dimensional Plume in Uniform Ground-Water
," ASCE Journal of Hydraulics, Wf4, April 1978, pp. 503-514. .
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ll
V.
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281
ACRONYMS, SYMBOLS, AND
DEFINITIONS
DNAPL
mis
LNAPL
SWDA
TOT
WD
WHPA
ACRONYMS
dense non-aqueous phase liquid
Integrated Risk Information System (an EPA toxicity database)
light non-aqueous phase liquid
Safe Water Drinking Act
time-of-travel (of a chemical released in the wellhead area)
used in this manual to mean the Wellhead Datasheet
Wellhead Protection Area
A
As
Q
S
T.
SYMBOLS
Attenuation of the contaminant due to transport
Attenuation of the contaminant in the saturated zone
Attenuation of the contaminant in the unsaturated zone
Likelihood of well contamination
Likelihood of contaminant release at the source
Likelihood of reaching the well if contaminant release occurs
Likelihood of transport through the saturated zone
Likelihood of transport through the unsaturated zone to the saturated zone
Quantity of contaminant expected to be released at the source
Severity of potential well contamination
Toxicity of the contaminant
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-if-
ACRONYMS, SYMBOLS, AND DEFINITIONS 282
DEFINITIONS1
Anisotropy - the condition of having different properties when measured along axes in different
directions. See its antonym - Isotropy.
Aquifer - a formation, group of formations, or part of a formation that contains sufficient
saturated permeable material to yield significant quantities of water to wells and springs.
Attenuation - to reduce, .weaken, dilute, or lessen in severity, value, or amount such as the
attenuation of contaminants as they migrate from a particular source. In the context of the
Priority Setting Approach, the Attenuation score actually reflects the lack of attenuation of the
contaminant; i.e., the higher the Attenuation score, the lesser the dilution and decay of the
contaminant-
Cone of Depression - A depression of the potentiometric surface in the shape of an inverted
cone that develops around a well which is being pumped.
Confined aquifer - an aquifer bounded above and below by confining units of distinctly lower
permeability than that of the aquifer itself.
Contaminant - an undesirable substance not normally present or an unusually high
concentration of a naturally occurring substance in water or soil.
Contamination - the addition to water of contaminants, preventing the use or reducing the
usability of the water. Sometimes considered synonymous with pollution.
Darcy's law - an empirical law that states that the velocity of flow through a porous medium is
directly proportional to the hydraulic gradient under certain assumptions.
Drainage well - a well installed to drain surface water, storm water, or treated waste water into
underground strata.
Flow, steady - a characteristics of a flow system where the magnitude and direction of specific
discharge are constant in time at any point.
1 Terms and definitions from (1) U.S. Department of Interior, U.S. Geological Survey, Federal
Glossary of Selected Terms: Subsurface Water Flow and Solute Transport, Reston, Virginia, 1989, (2)
U.S. Environmental Protection Agency, Office of Emergency Response, RCRA Ground-Water Monitoring
Technical Enforcement Guidance Document, Washington, D.C., 1986, (3) U.S. Environmental Protection
Agency, Guidance for Applicants for Wellhead Protection Program Assistance Funds under the Safe Water
Drinking Act, 1987, and (4) 40 CFR Section 144.6.
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ACRONYMS, SYMBOLS, AND DEFINITIONS 283
Flow, unsteady - a characteristics of a flow system where the magnitude and/or direction of
specific discharge changes with time.
Ground water - that part of the subsurface water that is in the saturated zone.
• : _ r
Ground-water flow - the movement of water in the zone of saturation.
Ground-water recharge - the process of water addition to the unsaturated zone or the volume
of water added by this process.
Ground-water velocity - see velocity, interstitial.
Heterogeneity - a characteristics of a medium in which material properties vary from point to
point.
Homogeneity - a characteristic of a medium in which material properties are identical
everywhere. •
Hydraulic conductivity - the volume of water that will move through a medium in a unit of
time under a unit hydraulic gradient through a unit area measured perpendicular to the direction
of flow. See also unsaturated flow.
Hydraulic gradient - slope of the water table or potentiometric surface.
Hydrogeology - the science dealing with the occurrence of groundwater, its utilization, and its
functions.
Hydrologic properties - those properties of a rock that govern the entrance of water and the
capacity to hold, transmit, and deliver water, such as porosity, effective porosity, specific
retention, permeability, and the directions of maximum and minimum permeabilities.
Impermeable - a characteristic of some geologic material that limits its ability to transmit
significant quantities of water under the head differences ordinarily found in the subsurface.
Infiltration - the downward entry of water into the soil or rock. Net infiltration - the amount
of rain, melting snow, or surface water, minus evaporation and plant transpiration, that enters
into the soil or rock.
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i JII'V'
ACRONYMS, SYMBOLS, AND DEFINITIONS 284
Injection well - a well into which fluids are being injected. The different kinds of injection
wells are:
Class I: Wells used to inject liquid hazardous wastes or dispose of industrial and
municipal waste waters beneath the lower-most underground source of drinking
water (USDW).
Class II: Wells used to dispose of fluids associated with the production of oil and
natural gas (hydrocarbons), to inject fluids for enhanced oil recovery, or for the
storage of liquid hydrocarbons.
Class III: Wells used to inject fluids for the extraction of minerals (i.e., solution
mining).
Class IV: Wells used to dispose of hazardous or radioactive wastes into or above a
USDW. The USEPA has banned the use of these wells.
Class V: Wells not included in the other classes and generally used to inject
nonhazardous fluid into or above a USDW.
Isotropy - the condition in which the property or properties of interest are the same when
measured along axes in any direction.
Non-point source - a source originating over broad areas, such as areas of fertilizer and
pesticide application and leaking sewer systems, rather than from discrete points.
Permeability - the property of a porous medium to transmit fluids under an hydraulic gradient.
Point source - any discernable, confined, or discrete conveyance from which contaminants are
or may be discharged, including, but not limited to, any pipe, ditch, channel, tunnel, conduit,
well, container, rolling stock, or concentrated animal feeding operation.
Porosity, effective - the ratio, usually expressed as a percentage, of the total volume of voids
available for fluid transmission to the total volume of the porous medium.
Potentiometric surface - an imaginary surface representing the static head of groundwater and
defined by the level to which water will rise in a tightly cased well.
Pumping rate - the rate at which ground water is pumped from an aquifer.
Recharge area - an area in which water reaches the zone of saturation by surface infiltration.
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ACRONYMS, SYMBOLS, AND DEFINITIONS 285
Reference dose - for non-carcinogens, the exposure threshold above which health effects begin
to occur.
Retardation factor - the ratio of the average linear velocity of ground water to the velocity of
the retarded constituent.
Saturated zone - that part of the earth's crust beneath the regional water table in which all
voids, large and small, are filled with water under pressure greater than atmospheric.
Solubility - the total amount of solute species that will remain indefinitely in a solution
maintained at constant temperature and pressure in contact with the solid crystals from which
the solutes were derived.
Transport - conveyance of solutes and particulates in the unsaturated or saturated zone.
Unconfined aquifer - an aquifer that has a water table.
Unconfined ground water - water in an aquifer that has a water table.
• Unsaturated flow - the movement of water in a porous medium in which the pore spaces are
not filled to capacity with water.
Unsaturated zone - the zone between the land surface and the regional water table. Generally,
water in this zone is under less than atmospheric pressure, and some of the voids may contain '
air or other gases at atmospheric pressure.
Utility chase - a trench or channel used to house water, gas, electricity, or sewer lines, or- other
such underground utility lines.
Velocity, average interstitial - the average rate of ground-water flow in interstices expressed
as the product of hydraulic conductivity and hydraulic gradient .divided by the effective
porosity.
Water table - upper surface of a zone of saturation, where the body of ground water is not
confined by an overlying impermeable zone.
Well - a bored, drilled, or driven shaft, or a dug hole, whose depth is greater man the largest
surface dimension.
Wellfleld - one or more wells in the same general area containing a distribution system.
. . . - . . .. '. -.
Wellhead - the portion of a well that extends above ground.
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ACRONYMS, SYMBOLS, AND DEFINITIONS 286
Wellhead Protection Area - the surface and subsurface area surrounding a water well or
wellfield, supplying a public water system through which contaminants are likely to move
toward arid reach such well or wellfield.
Zone of contribution - all areas that recharge or contribute water to a well or well field.
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