United States Office of Water 816-R-00-016
Environmental Protection Agency Washington, D.C. 20460 November 2000
v>EPA Technical Assistance
Document (TAD) for
Delineating "Other Sensitive
Ground Water Areas"
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Table of Contents
I. Introduction
LA. Purpose of this TAD 1
IB. Background 1
I.C. Linkages Between Class V Wells and Ground Water Protection Areas 2
I.D. Identifying and Delineating OSGWAs 3
I.E. Submission of Plans for Identifying and Delineating OSGWAs 3
I.F. Coordination with Other Programs and the Public 4
I.F.I. Completion of Source Water Assessments 4
I.F.2. Delineation of OSGWAs 5
I.G. Extensions for Delineating OSGWAs 5
I.H. Where to Go for More Information 5
II. Developing a Plan to Identify and Delineate OSGWAs 6
III. Delineating "Other Sensitive Ground Water Areas" 7
III.A. Areas Relative to Underground Sources of Drinking Water (USDWs) 7
III.A.l. AquiferAreas 7
III.A. La. Mitigating Factors: Hydrogeologic 9
III.A. l.b. Mitigating Factors: Land Use 9
III.A.2. Sole Source Aquifers (SSAs) 9
III.A.2.a. Mitigating Factors: Hydrogeologic 9
III.A.2.b. Mitigating Factors: Land Use 9
III.A.3. Aquifer Recharge Areas 10
III.A.S.a. Mitigating Factors 10
III.B. Areas Associated with Transient Non-Community (TNC) Public Water Supply Wells or
Domestic Water Supply Wells 10
III.B.l. Transient Non-Community PWS Wells 10
III.B.La. Mitigating Factors 10
III.B.2. Areas of Domestic Wells 11
III.B.2.a. Mitigating Factors 11
III.B.2.b. Individual Domestic Wells 11
III.C. Areas Supplying Ground Water Discharge to Surface Water Supplies of Drinking Water 11
III.D. Process for Identifying OSGWAs 13
III.E. Examples of the OSGWA Identification Process 14
Case Study: Hypothetical State A 15
Case Study: Hypothetical State B 17
Case Study: Hypothetical State C 19
IV. Time Line and Compliance Schedule for Delineating Other Sensitive
Ground Water Areas 21
Compliance Dates for Existing Motor Vehicle Disposal Wells in Other Sensitive Ground Water Areas 22
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I. Introduction
LA. Purpose of this Technical Assistance Document
This Technical Assistance Document (TAD) provides guidance to EPA Regions and States
with primary enforcement responsibility under the Safe Drinking Water Act (SDWA)
regarding EPAs interpretation of the requirement to delineate "other sensitive ground
water areas" (OSGWAs), as related to the Revisions to the Underground Injection Control
Regulations for Class V Injection Wells (40 CFR 145.23(f)(12)). The guidance is
designed to implement national policy on this issue in a consistent fashion.
The SDWA provisions and EPA regulations described in this document contain legally-
binding requirements. This document does not substitute for those provisions or regula-
tions, nor is it a regulation itself. Therefore, this document does not impose legally-bind-
ing requirements on EPA, States, or the regulated community, and it may not apply to a
particular situation based upon the circumstances. EPA and State decisionmakers retain
the discretion to adopt approaches on a case-by-case basis that differ from this guidance
where appropriate. Any decisions regarding a particular facility will be made based on
the applicable statutes and regulations. Interested parties are therefore free to raise ques-
tions and objections about the appropriateness of the application of this guidance to a par-
ticular situation, and EPA will consider whether or not the recommendations or interpreta-
tions in the guidance are appropriate in that situation. EPA may change this guidance in
the future.
This TAD provides Underground Injection Control (UIC) Programs with guidance on how
to identify and delineate OSGWAs. Exercising the option to identify and incorporate
these OSGWAs can be of great benefit in targeting a State's resources and strengthening
the overall approach to comprehensive drinking water source protection.
EPA recommends that persons using this TAD familiarize themselves with both the Class
V rule requirements applicable to motor vehicle waste disposal wells, as well as the provi-
sions of the EPA-approved Source Water Assessment and Protection (SWAP) Program for
their respective State.
IB. Background
The Revisions to the Underground Injection Control Regulations for Class V Injection
Wells (hereinafter referred to as "the Class V Rule") bans existing motor vehicle waste dis-
posal wells in areas critical for the protection of ground water. Owners or operators of
existing motor vehicle waste disposal wells may seek a waiver from the ban and obtain a
permit (40 CFR 144.88(b)(l)). (Note: The reader is referred to Chapter 5 of EPAs State
Implementation Guide for the Class V Rule [EPA 816-R-00-008] for an expanded discus-
sion of these permitting and closure requirements).
The new Class V Rule requirements apply only to owners and operators of existing motor
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vehicle waste disposal wells in two areas:
(1) ground water protection areas assessed under the State Source Water Assessment and
Protection (SWAP) Programs (40 CFR 144.88(b)(l)(i)), and
(2) other sensitive ground water areas (OSGWAs) as delineated by the UIC Program
(40 CFR 144.88(b)(l)(ii)).
Initially, the Class V Rule requirements for existing motor vehicle waste disposal wells
apply to wells in ground water protection areas that are local assessment areas for commu-
nity and non-transient non-community water systems that use ground water as a source
(40 CFR 144.87(b)(i)). States must then delineate OSGWAs where the rule will apply
next (40 CFR 144.87(c)). States may, as an option, apply the rule statewide without delin-
eating OSGWAs (40 CFR 144.87(f)). These OSGWAs are critical in the protection of
underground sources of drinking water (USDW) from contamination by Class V wells,
but are not designated as ground water protection areas. These areas may include highly
productive aquifers that supply transient non-community water systems (i.e., delineated as
part of the State SWAP Programs) or private wells, areas overlying sole-source aquifers,
aquifer recharge areas, karst aquifers, or other hydrogeologically vulnerable areas (40
CFR 144.86(g)).
1C. Linkages Between Class V Wells and Ground Water Protection Areas
A ground water protection area is a geographic area near and/or surrounding community
and non-transient non-community water systems that use ground water as a source of
drinking water. These areas receive priority for the protection of drinking water supplies.
Section 1453 of the SDWA requires States to delineate and assess these areas as part of
their State SWAP Programs. An assessment requires three main components:
delineation of source water protection areas,
inventory of potential contaminant sources in the delineated protection areas, and
determination of susceptibility of the water systems to contamination.
Upon completion of these steps, the results of a source water assessment must be made
available to the public A local source water assessment is considered completed when
the results of the assessment are made available to the public.
A detailed description of the delineation approach for ground water protection areas is
presented in each State's EPA-approved SWAP Program. In many States, the delineation
approaches for these areas are the same as their approved approaches for delineating well-
head protection areas. In cases where the State delineated zones or areas representing var-
ious levels of protection, the State will need to determine which areas correspond to
ground water protection areas for the purpose of the Class V Rule.
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As a part of the State SWAP Program, each State is required to complete assessments of
all transient non-community water systems in addition to community and non-transient
non-community water systems. The Class V Rule does not include source water assess-
ment areas of transient non-community water systems that use ground water as a source;
however, a State may include these areas as OSGWAs, if determined to be appropriate.
ID. Identifying and Delineating OSGWAs
In the Class V Rule, the requirements for motor vehicle waste disposal wells are expanded
beyond ground water protection areas to include OSGWAs as designated by the States, or in
the case of direct implementation (DI) programs, the EPA Regional Offices. Expanding the
rule to OSGWAs will give UIC Programs the flexibility to identify critical areas, in addition
to ground water protection areas, that require additional protection. The addition of these
areas in the rule gives the UIC Program authority (if it does not exist in current State statute
or regulation) to protect other important aquifers from potential damage by motor vehicle
waste disposal wells located in areas outside of ground water protection areas.
If determined to be unnecessary, a State has the flexibility not to delineate OSGWAs (40 CFR
144.87(f)). The State should be aware that if the decision is made not to delineate OSGWAs,
all motor vehicle waste disposal wells (except those wells located in ground water protection
areas) will be required to close or seek a waiver from the ban and obtain a permit by January
1, 2007 (40 CFR 144.87(f)). States should notify the EPA by December 29, 2000 of their
decision not to delineate OSGWA (as part of the UIC primacy revision packages) and apply
the rule statewide by January 1, 2007 (40 CFR 145.23(f)(12)). A State may decide not to
delineate additional sensitive ground water areas for a variety of reasons that include:
existing statewide ban of motor vehicle waste disposal wells,
new statewide ban of motor vehicle waste disposal wells (through revised rules),
absence of motor vehicle waste disposal wells across the State, and
the entire State consists of sensitive ground water areas.
I.E. Submission of Plans for Identifying and Delineating OSGWAs
The UIC Programs in Primacy States and EPA Regions (for DI States and Indian Tribes)
will be responsible for completing the delineation of OSGWAs. Primacy States must first
develop a plan for identifying OSGWAs (40 CFR 145.23(f)(12)).
In the case of DI Programs, the EPA Regions will work with their States and Tribes to com-
plete their plans for delineating OSGWAs and make them available for public comments by
December 29, 2000. This date was selected to correspond with the deadline established for
Primacy States. Public notice will be given regarding the plans availability. EPA may pro-
vide technical assistance to the States and Tribes and/or enter into a Memorandum of
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Understanding with them in developing the plans for delineating OSGWAs.
Upon approval by EPA, the States will have until January 1, 2004 to complete the delin-
eation process. If a State is making reasonable progress in completing the delineations
but needs additional time, the State may apply to EPA for an extension of up to one year
to complete its delineations (40 CFR 144.87(c)).
In the case of DI Programs, the EPA Regions will work with the States and Tribes to com-
plete the delineations by the January 1, 2004 deadline. EPA may provide technical assis-
tance to the States and Tribes and/or enter into a Memorandum of Understanding with
them in conducting the delineations of OSGWAs.
IF. Coordination with Other Programs and the Public
I.F.I. Completion of Source Water Assessments
Information exchange between the UIC and SWAP Programs is essential to the imple-
mentation of the Class V Rule.
For States with Primacy in both the Class V UIC and Drinking Water Programs, the
two Programs should work closely to ensure that the results of local assessments are
made known to the UIC Program and available to the public.
For States with Primacy in the Class V UIC Program but not the Drinking Water
Program, the State UIC Program should coordinate with EPA to ensure that the
results of local source water assessments are made known to the State UIC Program
and the public in a timely manner.
For States with Primacy in the Drinking Water Program but not the Class V UIC
Program, the EPA Regional Office will need to work closely with the State SWAP
Program to ensure that the results of local assessments are made available to EPA
and the public in a timely manner.
The results of local source water assessments will be made available to the general pub-
lic under the SWAP Program. However, the affected motor vehicle waste disposal well
owners and operators may not be aware that their wells are located in regulated areas
and are subject to the new requirements. Therefore, upon the completion of a local
source water assessment for a ground water protection area, the UIC Program is encour-
aged to notify owners and operators of motor vehicle waste disposal wells that have
submitted an inventory to the UIC program regarding their responsibilities in meeting
the Class V Rule requirements. In addition, outreach programs through trade organiza-
tions, building and plumbing inspectors, and local watershed associations can be used to
make well owners and operators aware of their compliance requirements.
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I.F.2. Delineation ofOSGWAs
For States with Primacy in the Class V UIC Program, the UIC Program should work
with other appropriate State agencies (e.g., State Geological Surveys and State Drinking
Water Programs) to develop the plans for delineating OSGWAs (i.e., assuming the UIC
program and the drinking water programs are in separate agencies or offices). It is also
important to consider experiences from the process of susceptibility determination (a
part of the source water assessment process) to develop the delineation approach for
sensitive ground water areas.
For DI Programs, EPA will work with the States and Tribes to develop plans for delin-
eating sensitive ground water areas. EPA may provide technical assistance to the States
and Tribes and/or enter into a Memorandum of Understanding with them in developing
the plans and conducting the delineations.
Upon the completion of the delineation ofOSGWAs, the UIC programs must make the
delineation results available to the public (40 CFR 145.23(f)(12)). The results should be
made public as soon as available but in any case no later than the completion date (i.e.,
January 1, 2004). Outreach efforts should be targeted to affected well owners and oper-
ators regarding their responsibilities in meeting the Class V Rule requirements. In addi-
tion, outreach programs through trade organizations, building and plumbing inspectors,
and local watershed associations can be used to make well owners and operators aware
of their compliance requirements.
I.G. Extensions for Delineating OSGWAs
EPA believes that all States will complete their delineation ofOSGWAs by the given
deadline. If a State requires more time to complete the delineation, it may apply for an
extension of up to one year (i.e., up to January 1, 2005). Such an extension will only be
granted if a State has made reasonable progress in completing its delineation but requires
more time to complete the task. A State must complete and submit the extension request
to EPA by June 1, 2003 (40 CFR 144.87(c)).
I.H. Where to Go for More Information
HOTLINE: EPA operates the Safe Drinking Water Hotline [1-800-426-4791] which can
answer questions about the regulations and programs developed under the Safe Drinking
Water Act, and provide federal and State contacts for specific information. It can also
provide information on drinking water publications.
INTERNET: EPAs Drinking Water Web site [www.epa.gov/safewater/] provides
information on EPA's implementation of SDWA, the contaminants regulated under
SDWA, educational activities and publications on drinking water, and links to other
drinking water web sites.
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II. Developing a Plan to Identify and Delineate OSGWAs
40 CFR 145.23(f)(12) provides items that States are expected to consider in developing their
other sensitive ground water area plan, including:
geologic and hydrogeologic settings,
ground water flow and occurrence,
topographic and geographic features,
depth to ground water,
significance as a drinking water source,
prevailing land use practices, and
any other existing information relating to the susceptibility of ground water to
contamination from Class V injection wells.
The following describes the plan elements:
Identify Sensitive Geologic Conditions This section of the plan should include methods
you will use to identify geographic areas in which Class V wells may penetrate or
otherwise impact aquifers in areas such as karst, fractured bedrock or other
shallow/unconsolidated aquifers.
Identify Legal Designations This portion of the plan should discuss the criteria you will
use in identifying aquifers or portions thereof that would be legally designated in your
State, including sole source aquifers.
Criteria used for Exclusion/Considerations for Final Designation of Other Sensitive
Ground Water Areas - A variety of factors could influence your decisions to include or
exclude an area. A State may want to consider factors such as: the depth to ground water;
the likelihood of use of the ground water resource; and the presence or absence of
confining layers that may protect the USDW.
Public Participation - As part of the primacy revision package, a State's plan for
designating OSGWAs is subject to public participation requirements. Public participation
may include stakeholder meetings, statewide publication with opportunity to comment,
public meetings, or other means.
Plan for Making Designations Known to the Public Once the delineations are
completed, it is critical that the public be aware of the delineations. A State can use a
similar approach to that developed by the State's SWAP Program.
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The rule (40 CFR 145.23(f)(12)) specifically states that a State's OSGWA delineation plan must
include a commitment from the State to:
complete all delineations of OSGWAs by January 1, 2004,
make the delineations available to the public after they are complete, and
implement the new Class V regulations in the delineated sensitive ground water areas by
January 1, 2007.
A primacy revision package that does not include a plan for the delineation of OSGWAs will be
considered incomplete unless the State indicates in the application that it does not intend to
delineate OSGWAs. If a State does not delineate OSGWAs, the motor vehicle waste disposal
well requirements of the Federal rule will then apply statewide to all owners and operators on
January 1, 2004, and they will be required to fully comply with the rule by January 1, 2007 (40
CFR 144.87(f)).
III. Delineating "Other Sensitive Ground Water Areas"
OSGWAs are areas that are hydrogeologically sensitive, and areas where maintaining the high
quality of ground water is critical. These latter areas could include: all or portions of sole-
source aquifer areas; areas with transient non-community water wells and/or clusters of domes-
tic wells; and areas that contribute baseflow to streams or reservoirs that supply, or may in the
future supply, public drinking water.
Designation of OSGWAs is described below. For the purpose of discussion, OSGWAs are cate-
gorized into three broad types: areas relative to USDWs, areas with transient non-community or
domestic drinking-water wells, and areas supplying ground water to surface water supplies of
public drinking water.
III. A. Areas Relative to Underground Sources of Drinking Water (USDWs')
Contamination of a USDW can occur when motor vehicle wastes percolate to a USDW, or
when wastes, already in a USDW, expand laterally within it. This TAD addresses only
downward percolation of motor vehicle waste to a USDW1.
III.A.l. Aquifer Areas
The identification of sensitive aquifers is perhaps the most critical concept in this TAD.
Some areas are prone to contamination by Class V wells, solely as a result of the nature
of the underlying aquifer.
1 In the very rare instances of deep Class V wells, States are directed to the document "Regional Assessment of Aquifer
Vulnerability and Sensitivity in the Coterminous United States" [EPA/600/2-91/043] for State maps showing aquifers and portions
of aquifers whose transmissivity makes them sensitive/vulnerable. States may also find EPA/600/2-91/043 helpful in identifying
areas where existing contaminants are most likely to spread laterally.
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Highly permeable aquifers are particularly at risk of contamination. This risk results
from the ease with which contaminant-laden water can percolate downward from the
motor vehicle waste disposal well to the saturated zone. Contamination is therefore
caused by vertical movement of water and contaminants from the waste disposal well to
the saturated zone. Large conduits such as well-developed fractures or karst features, or
large and well-sorted sediments, can provide rapid pathways for contaminants to reach
the saturated zone of an aquifer (Figure 1).
Pore space between
sediments in
unconsolidated
sedimentary
deposits
Rubble zone
and cooling
fractures in
extrusive
igneous rocks
Caverns in
limestone and
dolomite
Fractures in
intrusive igneous
rocks
Figure 1. Types of Openings in Selected Water-Bearing Rocks
States delineating OSGWAs may choose to begin by identifying aquifer areas. The Class V
Rule lists karst, fractured volcanics, and unconsolidated sedimentary aquifers, such as gla-
cial outwash deposits and eolian sands, as examples of aquifer types. The EPA urges States
to consider all aquifer types that, based on their inherent characteristics, are likely to be
moderately to highly sensitive. Such aquifer types are those that potentially have high per-
meability, such as fractured aquifers; porous media aquifers with a grain-size of sand or
larger, including not only unconsolidated aquifers, but sandstone as well; and karst aquifers.
State implementing agencies will need to discuss the selection of sensitive aquifer types
with their technical staff and/or professionals at such agencies as the State or Federal geo-
logical surveys.
State and Federal geological surveys have numerous geological maps and technical reports
that can be helpful in the identification of areas of sensitive aquifers. University geology
and earth science departments and consulting company reports may also have helpful infor-
mation. Because most States maps are likely to depict very generalized hydrogeologic
information, probably the best place for the Class V implementing agency to begin obtain-
ing information is the generalized geologic maps available for many States2. Consultation
with hydrogeologists or geologists at the State and Federal geological surveys can help
2 The U. S. Geological Survey (USGS), as part of its ongoing Regional Aquifer-System Analysis (RASA) and National Water
Quality Assessment programs produces maps showing basic hydrogeologic data at various scales. The RASA program is system-
atically studying 28 major aquifer systems across the country. A Ground Water Atlas for the United States is being developed.
Most of the 13 planned multi-State atlas sections have been published. More detailed maps are available from the USGS and
from State geological surveys.
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interpret and refine the geological maps, especially to identify areas where mitigating fac-
tors reduce the permeability of aquifers (see "Mitigating Factors" section below).
III.A.I.a. Mitigating Factors: Hydrogeologic
Any factors that prevent contaminated waste water from a motor vehicle waste dispos-
al well from entering a USDW could potentially serve as a mitigating factor. Although
all aquifer types have the potential to become contaminated by motor vehicle waste
disposal wells, mitigating factors such as a confining unit above the aquifer may exist
that reduce the likelihood of such contamination. Other factors include great depth to
ground water; poorly developed and/or connected geologic formations; formations
with very fine fractures or small grain size; and formations with poor sediment-size
sorting and/or high silt/clay content.
It is important to recognize that the threshold values for the effectiveness of mitigating
factors (e.g., thickness of a confining unit or depth to ground water) are generally
unknown. Additionally, threshold values will vary from location to location. For
example, an unsaturated zone "x" feet thick may be protective of the aquifer in some
settings, but not in others. State agencies implementing the Class V Rule will likely
need to confer with technical professionals while selecting mitigating factors and
threshold values.
III.A. 1 .b. Mitigating Factors: Land Use
A State may choose to delete a portion of a sensitive aquifer from consideration as
an OSGWA based on other criteria such as population density in different areas of
the aquifer or potential commercial/industrial development, etc.
III.A. 2. Sole Source Aquifers (SSAs)
Some States may choose to designate a Sole Source Aquifers (SSAs) as sensitive. By
definition, a SSA contains highly valued ground water. If a State chooses to designate
only a portion of the SSA, the State will need to select the criteria by which to identify
the non-sensitive portion of the SSA.
III.A.2.a. Mitigating Factors: Hydrogeologic
If a State chooses to identify only portions of the SSA that are hydrogeologically
sensitive, the approach used should be similar to the discussion of highly permeable
aquifers (see Section III.A.I.a. above).
III.A.2.b. Mitigating Factors: Land Use
If a State chooses to designate a portion of a SSA based on other-than-hydrogeologic
criteria, the criteria that could be used include population density in different areas
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of the aquifer or potential commercial/industrial development.
III. A. 3. Aquifer Recharge Areas
Identification of recharge areas of confined aquifers will require technical consultation.
Aquifer recharge areas of unconfined aquifers may be difficult to distinguish from
aquifer discharge areas. Where this difficulty exists, it may be necessary to undertake
hydrogeologic studies or consultation with technical experts on staff or in the State or
Federal geological surveys.
III.A.S.a. Mitigating Factors
In most cases, recharge areas of confined aquifers are sensitive. States may, however,
be able to identify factors that support the State's decision to not designate a recharge
area as an OSGWA. These factors might be hydrogeologic in nature, for example, low
productivity of the aquifer, or very long ground water travel time to any area likely to
have, or to develop, drinking water wells. Factors may also be based on land use, for
example, very low population density, or land uses that preclude development of drink-
ing water wells.
III.B. Areas Associated With Transient Non-Community (TNC) Public Water Supply (PWS^
Wells or Domestic Water Supply Wells
The Class V Rule does not define source water assessment areas of transient non-commu-
nity (TNC) public water system (PWS) wells and the area of ground water contribution to
domestic drinking water wells as sensitive. However, States may want to designate the
source water contribution area for such wells.
III.B. 1. Transient Non-Community Public Water System Wells
The source water assessment area of TNC wells will be delineated as part of a State's SWAP
Program. Additionally, the 1997 SWAP Program Guidance gives States the option of desig-
nating "area-wide source water protection areas," which are delineated areas from which
more than one PWS receive water. For the purpose of the Class V Rule, States could, in an
analogous fashion, identify as sensitive, individual TNC wells and/or those areas with
numerous TNC wells in the same hydrogeologic setting.
III.B. 1.a. Mitigating Factors
If States choose to refine the initial area-wide assessments for TNC PWSs, hydrogeo-
logic mitigating factors could be applied. The factors could include those discussed
above in Section III.A.I.a. Additionally, a State might wish to fine-tune by considering
other-than-hydrogeologic factors, such as those discussed above in Section IH.A.l.b.
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III.B.2. Areas of Domestic Wells
Some States may want to identify areas of domestic wells, in a manner analogous to
area-wide delineations for TNC PWS wells. A State could define areas containing
numerous domestic wells as OSGWAs. Because the discharge of domestic wells is low,
the boundary of such an OSGWA might only be tens of feet from the outermost domes-
tic wells in the cluster.
III.B.2.a. Mitigating Factors
Hydrogeologic mitigating factors could include those discussed above in Section
III.A.I.a. Additionally, a State might wish to consider other factors, such as those
discussed above in Section III.A.l.b.
III.B.2.b. Individual Domestic Wells
States also have the option of designating as an OSGWA, the contribution area about
an individual domestic well. However, the small size of the ground water contribu-
tion area combined with the lack, or imprecision of, locational information for these
wells, would likely render the mapping of these OSGWAs of little protective value.
III.C. Areas Supplying Ground Water Discharge to Surface Water Supplies of Drinking Water.
The areas of ground water contribu-
tion to hydraulically connected sur-
face water underlie and border rivers,
lakes and reservoirs. Protection of
PWS surface-water intakes should
recognize that ground water, via
baseflow to streams, is generally a
component, possibly a major one
(and during some parts of the year,
possibly the only component), of
streamflow (Figure 2).
Figure 2. Ground Water Entering Stream Via
Baseflow
As a result of the relationship between ground water and surface water, States may be con-
cerned about the quality of ground water that discharges to streams or reservoirs that supply,
or may in the future supply, water to PWS intakes. States may choose to designate all, or
some portion of, the ground water discharge area as an OSGWA. The difficulty that accom-
panies the identification of the boundary between recharge and discharge areas may confound
the designation of discharge areas as OSGWAs in the absence of hydrogeologic studies.
However, numerous options exist for a "managerial" decision regarding the area to be so des-
ignated. These options are identified in the EPA document "Delineation of Source Water
Protection Areas, A Discussion for Managers, Part 1: A Conjunctive Approach for Ground
Water and Surface Water" [EPA 816-R-97-012] published in October 1997 and they include:
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Floodplain boundary setback for perhaps the 20-, 50-, or 100-year flood. However, the
extent of the floodplain is not related to the areas through which ground water contributes
to surface water.
Hyporheic zone boundary setback that may be defined by specific biological or physical
parameters. The boundary of this zone can vary, depending on the defining parameter
used. The size of the zone can vary seasonally and in response to droughts; where biolog-
ical parameters are used, the extent of the zone may depend on how rapidly the microor-
ganisms recolonize.
5-Year distance
from stream -
1
Stream reach
\
2-Year ground water travel
time distance from stream
Figure 3. Two and Five Year Ground Water Travel Times to Reach Stream
Ground water travel time (Figure 3) and fixed distance setbacks rely on the ability of soil
and rock to improve water quality with time and ground water travel distance. Given the
current level of knowledge, specific distances needed for sufficient in-situ remediation are
generally unknown. These approaches are analogous to the travel-time and fixed-dis-
tance approaches used in the SWAP and Wellhead Protection (WHP) programs for wells.
Ground water basin boundary that marks the furthest locations from which ground water
will flow to a stream or other drain. The position of the boundary may vary seasonally
and with climatic changes. The position of the boundary is often assumed to coincide
with the position of the watershed boundary. While this assumption is not always true, it
may be a sufficiently reasonable assumption for the purposes of the Class V Rule for most
settings except karst.
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HID. Process for Identifying OSGWAs
This subsection provides a process that States can use for identifying OSGWAs. This process
can be stopped at any step. Additional steps will provide smaller, more fine-tuned OSGWAs.
Step One: Selecting Criteria to Identify Inherently Sensitive Areas
States decide which types of hydrogeologic and/or land use features would make an area
inherently sensitive. It is these features that, when mapped, will constitute the broad, first-
round delineation of OSGWAs.
Hydrogeologic Features:
States may identify the aquifer types within their boarders that are inherently sensitive.
States should consider including sandstone aquifers, karstic aquifers, fractured aquifers,
and unconsolidated aquifers (except those of very fine grain materials). States should also
consider identifying highly productive aquifers as sensitive.
Land Use:
States may identify the land uses that are considered inherently sensitive. Land uses may
include areas of highly valued water, areas of high-population density, etc., that could be
adversely impacted by the presence of motor vehicle waste disposal wells. For example,
many States will likely include SSAs in their list of inherently sensitive features.
Step 2: Delineation of Broad Inherently Sensitive OSGWAs
States map the selected features identified in Step 1; that is, the boundaries of all inherently
sensitive areas are drawn on a base map. Statewide geologic or hydrogeologic maps exist
for many States and are available from the State or Federal geological surveys. Using a
geological map as the base map will likely be easier than transferring geologic information
to another base map.
Identification of inherently sensitive hydrogeologic features on geologic or hydrogeologic
maps will likely require the assistance of staff professionals or geological survey professionals.
All SSAs have been mapped. Delineation of other land use features, such as areas of high
population density, will likely need the cooperation of sister agencies.
Step 3: Selection of Mitigation Factors
States, in consultation with experts in such fields as city planning, resource management,
and hydrogeology, identify the critical factors that will allow the fine-tuning of the broad
OSGWAs developed in Step 2. Among the criteria most likely to be considered are:
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Technical
confining units above the aquifer,
depth to ground water,
area is/is not an aquifer recharge area,
area is/is not a source of ground water discharging to a surface water
body that supplies, or in the future may supply, a PWS intake, and
aquifer productivity.
Non-technical
land use,
likelihood of commercial/residential/industrial development,
low population density, and
significance of the aquifer as an existing or future drinking water source
in the area.
Step 4: Second-Round Delineation ofOSGWAs
Consideration of the mitigating factors selected in Step 3 may result in portions of the initial
OSGWAs no longer being considered sensitive. These areas are deleted from the base map.
Step 5: Decision to Continue the Refinement Process
States evaluate the second-round OSGWAmap and decides if the second-round map pro-
vides appropriately protective areas. The States have two choices:
The map provides appropriately protective OSGWAs. The OSGWA
selection process ends.
The State identifies additional mitigating factors, repeats steps 3 and 4 to
further refine OSGWAs.
III.E. Examples of the OSGWA-Identification Process
Attached are the case studies of hypothetical States applying the OSGWA-identification
process described above.
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CASE STUDY: HYPOTHETICAL STATE A
Introduction
State A (Map A) consists of six "sensitivity features." These have been identified by technical
experts in the Class V implementing agency, in consultation with the U.S. Geological Survey.
There is no statewide geologic map for the State and therefore the State will transfer informa-
tion from existing maps and "fill in" generalized aquifer boundaries, where needed, through
consultation with the State and Federal geologic surveys.
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B River
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Map A
Zone A consists of a vertical sequence of poorly fractured, low productivity aquifers, the
shallowest of which has a deep water table.
Zone B is an SSA consisting of moderately karstified limestone.
Zone C is a highly productive, confined aquifer of alluvial sand and gravel.
Zone D is the outcropping recharge area for the sand and gravel aquifer of zone C.
Zone E is hydrogeologically the same as Zone D, but is a state park with primitive
camping only, virtually no development and a very low population density.
Zone F is alluvial sediments associated with the modern river that flows north-south
through the center of the State. The river has cut through the confining layer of Zone D
and most of the river's alluvium rests directly on the underlying aquifer. Only the edges
of the alluvium lie on the confining unit.
The State has chosen to not separately delineate the area of ground-water recharge to the river.
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Process
Step 1: The implementing agency selected the features that it considered sensitive: SSAs,
karstic aquifers, and coarse-, or moderately coarse-grained unconsolidated aquifers.
Step 2: The State will then select mitigating factors.
Step 3: Mitigating factors - the State identified confinement and the presence of a deep water
table as the two primary factors that remove features from consideration as an
OSGWA.
Step 4: After discussion with, and assistance from, technical professionals, the State put together
an OSGWA map, based on the mitigating factors selected in Step 2. This revised
OSGWA map contains Zones B, D, E, and F. These zones cover about 30% of the State,
however, the state park accounts for about one third of this area, and it has only two
motor vehicle waste disposal wells that the State is already in the process of closing.
Step 5: The State decides that the OSGWAs identified in Step 4 will be the final OSGWAs to
satisfy the requirement of the Class V Rule.
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CASE STUDY: HYPOTHETICAL STATE B
Introduction
State B (Map B) consists of seven hydrogeologic settings. These settings were identified
through discussions with the State geological survey. A 1:250,000 geologic map is available for
State B. This scale allows the identification of major geologic features only. However, these
major features are sufficient for the implementation of the Class V Rule.
\
r
/
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D
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River
Map B
Zone A is an outcrop area of consolidated sandstone. The water table is shallow.
Zone B is a finely fractured, low productivity aquifer. The area is one of rugged
mountains and the population density is, and will most likely continue to be, quite low.
Zone C consists of a highly productive, tightly confined sand and gravel aquifer. It is
part of the SSAthat includes Zones D and E.
Zone D is part of the SSA and is hydrogeologically similar to Zone C, except that the
confining layer is leaky. Ground water discharges from the aquifer to the stream
throughout most of this zone.
Zone E is the recharge area for the SSA and is included in the designated SSA.
Zone F consists of unconsolidated sand and is essentially the 50-year floodplain of the
modern river.
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Process
Step 1: After discussions with the State and Federal geological surveys and with resource
managers, the State selects the criteria for identifying sensitive areas. The State will
use hydrogeologic criteria and land use criteria:
Hydrogeologic criteria - fractured rocks, unconsolidated sediments and sandstones are
considered inherently sensitive.
Land use criteria - SSAs are considered inherently sensitive.
Step 2: The State maps the broad, first-round OSGWAs and determines that, based on the
criteria selected in Step 1, the entire State is an OSGWA.
Step 3: The State selects mitigating factors that will reduce the size of the OSGWAs. The
State selects hydrogeologic factors and land use factors:
Hydrogeologic areas that are highly confined are not sensitive.
Land use - areas with very low population density are not sensitive.
Step 4: Second-round delineation of OSGWAs. Based on the mitigating criteria selected in
Step 3, the second-round OSGWAs consist of Zones A, D, E, and F. The OSGWA
map shows that approximately half of the State is an OSGWA.
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CASE STUDY: HYPOTHETICAL STATE C
Introduction
State C (Map C) consists of five sensitivity areas:
Western Central
River River
Map C
Zone A consists of a highly productive, unconfmed volcanic aquifer with a moderately deep
water table. The topography is one of rolling hills. Over the last decade the population has
been gradually increasing and the area is undergoing residential and commercial development.
Zone B consists of a low productivity sequence of confined silty sand layers. The
population density is about the mean for the State.
Zone C consists of a low productivity sequence of unconfmed silty sand layers. The
population density is very low.
Zone D is fairly flat, with a shallow water table. The aquifer is a highly productive sand
and gravel. Zone D historically has had a very low population density and was almost
entirely agricultural. However, the southeastern portion (D') is slowly undergoing urban
sprawl; its population is growing and agriculture is giving way to development.
Zone E is underlain by unconfmed, coarse, alluvial sediments deposited by the river that
flows through the central part of the State. The aquifer is highly productive and has a shal
low water table. As is often the case, there is considerable development along the river and
the population density is high. (Note that the alluvial valley of the western river is deep and
too narrow to be shown on the map.)
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Sub zone F consists of the area where aquifers contribute ground water to the western river.
(Note that Subzone F is part of, and superimposed on other zones.) The position of the
boundary of the area of ground water contribution to the river, was based on the position of
a roughly calculated 10-year ground water-travel time to the stream (i.e., the same standard
used in the WFtP and the SWAP Programs). (Note: The 10-year travel time zone is not
shown for the central river; this is because the 10-year zone is totally contained in the allu-
vial valley and will be incorporated into the floodplain area's designation as an OSGWA, as
described below.)
No State geologic map exists. Map C is composed of the very generalized geologic boundary
information pieced together from numerous maps. The geologic boundaries shown on Map C are
only approximate, because the generalized nature and the scale of this map.
Process
Step 1: After discussions with the State and Federal geological surveys and with resource man-
agers, the State selected hydrogeologic criteria for identifying sensitive areas as follows:
areas with a coarse- or moderately coarse-grained, unconsoli dated aquifer, areas with a
fractured volcanic aquifer, and areas of ground water discharge to surface water sources
of public drinking water. There are no karst aquifers or fractured aquifers, other than vol-
canic, in the State.
Step 2: The State mapped the broad OSGWAs that met the selection criteria in Step 1. The
OSGWA map consists of Zones A, D, E, and F. In total, the OSGWA areas cover about
60% of the State.
Step 3: The State then selected mitigation criteria. The mitigating factor chosen to modify the
initial OSGWA map was the presence of a deep water table.
Step 4: Upon applying the mitigating factors in Step 3 to the first-round OSGWA map, the areas
that remained OSGWAs are Zone D, Zone E, and the southern half of Subzone F, a total
area of about 25% of the State.
The State was concerned that any further fine-tuning would result in underprotection. However,
they did want to further prioritize area to be protected against motor vehicle waste disposal wells.
Upon discussion of options with technical experts and resource managers, the State decided to
carefully craft an additional mitigating factor. That is, the State decided to continue the process by
returning to Step 3.
Step 3: The State applied a final mitigating factor, very low population density (except for areas
discharging ground water to streams supplying PWSs).
Step 4: The OSGWA map was revised to reflect the additional mitigating factor. The remaining
OSGWAs (Zones D', E, and the southern half of F) appeared to be protective and, occu-
pying about 10% of the State, will facilitate implementation of the Class V Rule.
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IV. Time Line and Compliance Schedule for Delineating Other Sensitive Ground Water
Areas
A summary of the time line for States to delineate OSGWAs is presented in the following table (40
CFR 144.87(c) and 40 CFR 145.23(f)(12)).
Time Line for States to Delineate Other Sensitive Ground Water Areas
Action Item
Requirement Date
Submission of Delineation Plan by Primacy State
(with the Primacy Revision Package)
December 29, 2000
Application for Extending the Deadline to Delineate
Other Sensitive Ground Water Areas by States (if needed)
June 1, 2003
Completion of the Delineation of Other Sensitive Ground
Water Areas by States (without the one-year extension
granted by EPA)
January 1, 2004
Completion of the Delineation of Other Sensitive Ground
Water Areas by States (with up to a one-year extension
granted by EPA)
Up to January 1, 2005
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Compliance Dates for Existing Motor Vehicle Disposal Wells
in Other Sensitive Ground Water Areas
A State must complete the delineation of other sensitive ground water
areas by January 1, 2004 unless it is granted a one-year extension to
complete the delineation by no later than January 1, 2005.
A well owner and
operator has a motor
vehicle waste disposal
well (according to 40
CFR 144.85) that is
located in a sensitive
ground water area.
The State completed the
delineation of other sensitive
ground water areas by
January 1,2004.
The State applied for and
recieved up to a one year
extension to complete the
delineation by no later
than January 1, 2005.
A well owner or operator has
until January 1, 2007 to close the
well or operate under permit conditions.*
V J
A well owner or operator has
until January 1, 2008 to close the
well or operate under permit conditions.
*The well owner or operator can apply for a one-year extension if his or
her compliance option is connection to a sanitary sewer or installation of
new treatment technologies. On a case by case basis, the State and EPA
UIC Program will consider review the application for approval. This one-
year extension, however, does not apply to the permit application deadline.
In addition, this one-year extension is not available when a State is
granted a one-year extension to complete its delineation of other sensitive
ground water areas.
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