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.
                                               8

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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

                                         9

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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:

                                            13

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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.
/ill
lğl
B River
\
\
\ D
1;
                                         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.
                                           15

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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.
                                           16

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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
                                                      /
                          \
                         D
                             \
                                \
                                  \
                       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.
                                           17

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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.
                                           18

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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.)
                                            19

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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.

                                            20

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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
                                         21

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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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