oEPA
            UnflM states
            Enyironmsnui Protection
            Office of Ground-Water
            Protection (WH-S50G)
            Washington, DC 20*60
June 1988
            Offio of w«t«r
Guidelines for
Ground-Water
Classification Under
the EPA Ground-Water
Protection Strategy

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  GUIDELINES FOR GROUND-WATER CLASSIFICATION
UNDER THE EPA GROUND-WATER PROTECTION STRATEGY
                  JUNE 1988
      OFFICE OF GROUND-WATER PROTECTION
     U.S.  Environmental Protection Agency
              401 M Street. S.W.
           Washington, D.c.  20460

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                       ACKNOWLEDGEMENTS

     These Guidelines  were  prepared  by  the Office of Ground-
Water Protection  under the  overall guidance of the Director,
Marian  Mlay.    The  project  aanger was  Ron  Hoffer,  with
additional  technical  support  provided  by  Joee  Valdes  and
Donna Fletcher.   Assistance in developing  the socioeconomic
and ecological  aspect of the system was provided by Brendan
Doyle and Arthur  Koines of  the Office of Policy Planning and
Evaluation.   Joyce  Edwards  of  OGWP helped  in the secretarial
and logistical aspects of this document from the inception of
the project.   The  efforts  of the Classification Guidelines
Work  Group  in   the  development  of   the  Final   Draft
Classification  Guidelines  (December,   1986)  are  especially
appreciated.

     Technical consultants  played a significant  role  in the
preparation  of  these  guidelines.    The  primary  technical
consultant was  Geraghty  &  Miller,  Inc.  (G&M),  Dr.  William
Doucette, project manger.   Other members  of the  G&M support
team  included Don  Lundy,  Michele Ruth  and  Laurie  Haines.
Shirley Reeder and Xaren Kotschenreuther at G&M performed the
majority  of  word processing.    Subcontract  assistance  was
provided  by  ICF,  Inc., Peter   Linguiti  and Paul  Bailey,
project  managers.    Other   ZCF   support  team members  were
Richard Norton and Joseph Karam.

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                         DISCLAIMER
     These Ground-water  Classification  Guidelines are  meant
to assist  the U.S.  Environmental Protection  Agency as  the
Agency  moves  forward   in  ground-water  protection.     The
Guidelines   do  not   create  any  rights  or  obligations,
substantive or  procedural,  enforceable  by  any  party in  an
administrative,  civil,  or criminal proceeding.
                            6-27

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                        TABLE OF CONTENTS

                                                             PAGE

ACKNOWLEDGEMENTS


TABLE OF CONTENTS	   i


LIST OF FIGURES	   v


LIST OF TABLES...	   vii


EXECUTIVE SUMMARY	   E-l


CHAPTER ONE:   INTRODUCTION	   1-1

   1.1   EPA's Ground-Water Protection Strategy.	   l-l

   1.2   Purpose of the Classification Guidelines	   1-2

   1.3   Guideline Development	   1-2

   1.4   Organization of Guidelines Document...	   1-3
CHAPTER TWO:   OVERVIEW OF THE GROUND-WATER
               CLASSIFICATION SYSTEM AND PROCESS	   2-1

   2.1   Ground-Water Classes	   2-2

      2.1.1    Class I - Special Ground Waters	   2-2
      2.1.2    Class II - Current and Potential Sources
               of Drinking Water and Water Having other
               Beneficial Uses.	   2-2
      2.1.3    Class III - Ground Water Not a Potential
               Source of Drinking Water and of Limited
               Beneficial Use	   2-4

   2.2   General Classification Procedures	   2-5

   2.3   Collection of Basic Information	   2-8

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                       TABLE OF CONTENTS  (CONT.)


CHAPTER THREE:  THE  CLASSIFICATION REVIEW AREA	   3-1

   3.1   Purpose of  the Classification Review Area	   3-1

   3.2   Determining the Classification Review Area........   3-2

      3.2.1    Introduction	   3-2

   3.3   Expansion of the Classification Review Area	   3-4

      3.3.1    Introduction	   3-4
      3.3.2    Determining Whether Expansion is Warrant ad...   3-5

   3.4   Subdivision of the Classification Review Ar«a	   3-10

      3.4.1    Introduction	. .*.	   3-10
      3.4.2    Concepts of Ground-Water Units and
               Interconnection	   3-12

   3.5   Characterizing the Classification Review Area	   3-14

   3.6   Location of the Classification Review Area
         Boundary Relative to the Facility/Activity
         Boundary	   3-19
CHAPTER FOUR:  CLASSIFICATION CRITERIA FOR CLASS I
               GROUND WATER	   4-1

   4.1   Overview of the Decision Process	   4-1

      4.1.1    Definitions	 •  4-1
      4.1.2    General Procedures	   4-2

   4.2   Procedures for Determining "Irreplaceable
         Source for • Substantial Population"	• • • •   4-8

      4.2.L   Step 1:  Determination of Substantial
               Population	   4-10
      4.2.2    step 2:  Screening Tests to Make Preliminary
               Determinations	   4-11
      4.2.3    step 3:  Use of Qualitative criteria for
               Final Irreplaceability Decisions	   4-28

   4.3   Procedures for Determining Ecologically Vital
         Areas	   4-30
                                ii

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                       TABLE OF CONTENTS (CONT.)


4.4   Procedures for Determining Highly Vulnerable
         Areas	.,	„	    4-32

      4.4.1    Factors Related to Vulnerability	    4-33
      4.4.2    Evaluation Aids for Assessing Vulnerability.    4-40
CHAPTER FIVE:  CLASSIFICATION CRITERIA FOR CLASS II
               GROUND WATER	,	   5-1

   5.1   Overview, of the Decision Process	   5-1

      5.1.1    Subclass IIA:  Current Source of Drinking
               Water	   5-1
      5.1.2    Subclass IIB:  Potential Source of Drinking
               Water	   5-4

   5.2   Classification Procedures	   5-5
CHAPTER SIX:    CLASSIFICATION CRITERIA FOR CLASS III
               GROUND WATER	    6-1


   6.1   Overview of the Decision Process	    6-1

      6.1.1    Definition of Class III	    6.1
      6.1.2    Purpose of and Policies Related to
               Class III	    6-1
      6.1.3    General Procedures	    6-2

   6.2   Class III Designation Based on Insufficient
         Yield	    6-4

   6.3   Class III Designation Based on Ground water
         Quality and Treatability	    6-6

      6*3.1    Areal Extent of contamination	    6-6
      6.3.2    Standards and Criteria for Treatment	    6-10
      6.3.3    Overview of Class III Treatability Test,....    6-11
      6.3.4-    Reference Technology "Screening Test1*..	    6-11
      6.3.5    Economic Untreatability Test	    6-22

   6.4   Subclasses of Class III	    6-25

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                        TABLE  OF CONTENTS  (CONT.)


BIBLIOGRAPHY	   B-l


GLOSSARY	   G-l


APPENDIX A:   Supplemental  Information:  Classification
              Review Area	   A-l


APPENDIX B:   Supplemental  Information:  Class I
              Procedures	   B-l


APPENDIX C:   Supplemental  Information:  Class III
              Procedures	_	   c-i


APPENDIX D:   Supplemental  Information:  Class I and
              Class  III  Economic Tests	:	   D-l
                                iv

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LIST OF FIGURES
2-1.
2-2.

3-1.


3-2.
3-3.
3-4.
3-5.
3-6.
4-1.

4-2.

4-3.
4-4.


4-5.

4-6

4-7.
5-1.

5-2.
6-1.
6-2.

6-3.

Summary of Ground-Water Classes 	
Schematic Chart of General Classification
Procedures 	 	
Hypothetical Classification Review Area
Shoving Potential Class Determining
Factors 	
Ground Water Regions of the U.S 	
Large Facility 	 	 	 	 	
Large, Multiple-Activity/Facility 	
Small, Multiple-Activity/Facility. 	 	 	
Long, Irregularly Shaped Facility 	
General Procedure for Class I

Suggested Method for Determining Irreplace-
ability to Substantial Populations 	
Potential Institutional Constraints 	
Outline of Procedure for Analyzing Potential
Institutional Constraints to the Use of an

Ninetieth Percentile Economic Thresholds by
System Size 	 	
Ninetieth Percentile Economic Thresholds by

Illustration of Drastic Mapping 	
. Example Class IZ - Current Source of
Drinking Water 	


Example of Contamination that Should Not

Example of Contamination that May Qualify
For Class III Designation 	
2-3

2-6


3-3
3-7
3-20
3-21
3-22
3-22

4-3

4-9
4-17


4-18

4-26

4-27
4-47

5-3
5-6
6-3

6-8

6-9

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                        LIST OF FIGURES (CONT.
6-4.    Alluvial Aquifar Separated Into Two Ground-
        Water Units with High Interconnection to
        a River	    6-27

6-5.    Cloned Basin/Arid Cliaatie Setting Containing
        a Classification Rtvisv Area with a Singl«
        Ground-wat«r unit	    6-28

6-6.    Exaapla of Probabl* Class IZB Ground Water..    6-30
                                vi

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                             LIST  OF  TABLES
4-1.    Generally Applicable Uncommon Pipeline
        Distances	   4-15

4-2.    Factors Relevant to Judging Vulnerability
        to Contamination	   4-34

4-3.    Ranges and Ratings for Depth to Water as
        Used in the Numerical Rating System
        DRASTIC	.	   4-49

4-4.    Generalized Site Grade Based on Critical
        Hydrogeologic Parameters	   4-52

6-1.    Reported Typically Achievable Contaminant
        Removal Efficiencies	   6-13

6-2.    Description of Treatment Process	   6-14

6-3.    Effluent Quality Working Table from Sample
        Problem	   6-21
                               vii

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                      EXECUTIVE SUMMARY

Introduction

     In August 1984, the U.S. Environmental Protection Agency
(EPA)  issued  a  Ground-Water Protection Strategy, setting out
the  Agency's  plans  for  enhancing  ground-water  protection
efforts  by EPA  and the  states.   A  central feature  of the
Strategy  is  a   policy  framework  for EPA's programs  which
accords differing  levels  of protection to ground water based
on the resource's use, value to society,  and vulnerability to
contamination.   A three-tiered ground-water  classification
system was  established  in the Strategy  as a key operational
tool to help implement this policy.

     The classification system recognizes that special ground
water exists  due to its high vulnerability to  contamination
and high value  for drinking-water  purposes or its importance
to a unique ecological habitat  (Class  I).   The  vast majority
of the nation's  ground  water  falls  within Class  II  which
encompasses all  non-Class  I current or  potential  sources of
drinking water.   Class III  ground water  is not a potential
source   of  drinking  water  primarily  due to  levels  of
contamination either  from naturally occurring  conditions or
the  effects  of  broad-scale  human activity  that cannot  be
feasibly cleaned up.

     These  Final  Guidelines for  classifying  ground  water
augment the Ground-Water Protection Strategy by

     e    Further defining the key terms and concepts of the
          classification system,  and

     e    Describing  procedures  and  data  requirements  to
          assist in classifying ground water.

     The procedures in  the Final  Guidelines  are  generally
intended for  site-specific ground-water  classification based
on a  review  of  the  segment of ground  water  in  relatively
close  proximity  to  a  particular  source.    Although  the
specific procedures are not designed specifically for broader
aquifer classification,  many of the concepts and procedures
developed for site-by-site classification will also be useful
in such classification efforts.

     The manner  and extent  to which  the Guidelines  will be
incorporated  into  EPA regulatory,  permitting,   and  planning
decisions  are  addressed  in a  supplemental  Implementation
Policy   statement  being   issued  concurrently  with  the
Guidelines.

     The  key  criteria   for  each   class  and  procedural
approaches for determining whether the criteria are  met are
outlined as follows:

                             E-l

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Classification Review Area

     The  first step in  making a classification decision is
defining the area around the source that should be  evaluated.
Once  this Classification  Review Area  has been determined,
information regarding public and private wells,  demographics,
hydrogeology, and surface water and wetlands is collected and
a classification  decision  is made based on the criteria for
each class as described below.

     The Guidelines  specify  an initial  Classification Review
Area  as  the area within a 2-mile radius of the boundary of
the  facility  or  activity  under  review.    Under  certain
hydrogeologic   conditions   an   expanded   or  reduced
Classification Review Area is allowed.

     It  should be emphasized  that the  Classification Review
Area  defines  a study area as one necessary »-j evaluate the
appropriate ground-water class in connection with  a specific
site  analysis  and  does  not  imply  that action needs  to be
taken relative to other facilities within the area.

Class 1 - Special Ground Water

     Class  I  ground  waters  are defined as  resources  of
particularly high value.   They are hicthlv vulnerable and are
either  an  irreplaceable  source  of drinking  water  for   a
substantial population or ecologically vital.

     e    Hiohlv vulnerable  ground water is characterized by
          a  relatively high potential  for contaminants to
          enter and/or be transported within the ground-water
          flow  system.     The  Guidelines   provide  both
          quantitative  and  qualitative  decision  aids  for
          determining  vulnerability  based on  hydrogeologic
          factors.

     •    An  irreplaceable  source  of  drinking water  for  a
          •ubstantial  population   is   ground water  yhose
          replacement  by  water  of   comparable  quality  and
          quantity from alternative source* in the  area would
          be   economically   infe&sible  or  precluded  by
          institutional  barriers.    The  determination  of
          irreplaceability is  based on  a  three-step process
          that  includes  identifying   the presence  of   a
          substantial  population,  applying screening tests
          designed  to produce a preliminary  determination,
          and  reviewing  relevant  qualitative  criteria  in
          order to produce a final determination.

     e    Ecologically  vital  ground water  supplies   a
          sensitive  ecological system  located  in  a ground-
          water   discharge   area  that  supports  a  unique

                             E-2

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          habitat.    Unique  habitats  include  habitats  for
          endangered  species listed or proposed  for listing
          under the Endangered Species Act as veil as certain
          Federally managed  and protected lands.


C?.ass  II - Current  and Potential Sources of  Drinking
and Ground Water Having Other Beneficial Uses

     Class  II ground waters include all non-Class  I ground
water   that   is   currently  being  used  or  is  potentially
available for drinking water or other beneficial use.

     Subclass IIA  is a  current source  of drinking water.
     Ground   water   is   classified   as  IIA  if  within  the
     Classification  Review Area  there  is either  (1)  one or
     more operating drinking-water wells or springs, or (2) a
     water-supply reservoir  watershed (or portion of it) that
     is  designated  for water-quality protection  by either a
     State or a locality.

     Subclass IIB  is a  potential source of drinking water.
     This  ground water  (1)  can be  obtained   in sufficient
     quantity to meet the minimum needs of an average family;
     (2) has  total dissolved solids (TOS) of less than 10,000
     milligrams  per liter  (mg/L) ;  and  (3)  is of  a quality
     that  can  be  used without  treatment  or that can  be
     treated  using  methods  reasonably  employed  by public-
     water systems.


Class  III -  Ground  Water Not a  Potential Source  of Drinking
Water and/or  Limited Beneficial Use

     Class  III  drinking  waters  have  either  (1)  a  TDS
concentration equal  to  or greater  than 10,000 mg/L;  or  (2)
contamination  by naturally  occurring conditions  or by  the
effects of broad-scale  human activity that  cannot be cleaned
up using treatment  methods reasonably  employed   in public-
water  systems.    A  two-step teat,  based on  technical  and
economic feasibility, is  presented  in the Guidelines.  Class
III also encompasses  those  rare conditions where (3)  yields
are  insufficient to  meet the  minimum needs  of   an average
household.     Subdivisions   within   Class  III  include  the
following:

     Subclass IIIA around water has an intermediate decree of
     interconnection with  adjacent  ground-water units and/or
     are interconnected with surface waters.

     •Subclass  TUB  ground  water  has  a  low   degree   of
     interconnection with adjacent ground-water units.
                             E-3

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                         CHAPTER ONE

                         INTRODUCTION
1.1         EPA'8  Ground-Hater  Protection Strategy
     EPA currently administers more than eight statutes which
direct the  Agency toward reducing.or  eliminating  threats  to
ground water from  a  large  number  and  variety of  sources..
This is a far-from-simple task and one which commands a major
part of the Agency's budget and personnel resources.   Changes
in  statutes and  resulting  regulations have occurred  in  the
past, and  will  continue to  occur in the  future,  to further
manage these pollution  sources.    Through EPA's  long-range
planning efforts and, more recently, an Agency-wide direction
toward overall  risk  management, ground-water  protection on a
cross-media basis is receiving increased attention.

     An important tool in this cross-program phase  was made
available in August  1984 when EPA  released  its Ground-Water
Protection  Strategy.   The  Strategy consists  of  four  major
elements:

     •    Strengthen State  Institutions  — through technical
          assistance and State Grants.

     •    Cope with Contamination Sources of National Concern
          — through source-specific protection programs.

     •    Zaprov« consistency in  Ground-water  protection
          decision*   —  through  the   establishment  and
          implementation of protection policies.

     •.   Strengthen  EPA   Institutions  —  through  the
          establishment  of  coordinating  functions  within the
          Offices of Ground-Water Protection  at Headquarters
          and in the Regions.

     Pursuant to the  third  element,  the  Agency  adopted  a
differential protection policy which acknowledges that ground
waters vary  in  terms of  their current  use, relative value to
society,  and vulnerability  to contamination.   Ground-water
classification was introduced in  the Strategy as an approach
for  setting priorities  for  regulatory  action  and  resource
management within this framework.

                             1.1

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1.2        Purpose of the Classification Guidelines
     This  document  provides  technical  guidelines  for  the
classification   system  established   in   the   Ground-Water
Protection  Strategy.     When  the  procedures   and  methods
outlined in this document are followed, ground water  that may
be affected  by a facility or  activity under  EPA review will
be placed within  a  relevant  class or classes  which represent
an implied hierarchy of protection.   This  document should be
viewed  essentially  as  a  set  of technical  guidelines  for
ground-water  evaluation via  classification.    The issue  of
implementation  of   the  Classification  Guidelines  by  EPA
programs  is   addressed in a  separate Implementation  Policy
Statement.

     It  is  important  to  note  that these Guidelines are  not
designed specifically  for classifying large segments  of land,
aquifers,   etc.,   in   advance  of  any   specific decision.
Instead,  the  system,  focuses  on  the  classification of  the
ground water  around specific sites or areas where a  decision
related to a  permit, degree  of clean up or regulation,  etc.,
is to be made.   The methods  and techniques in the Guidelines
will, however, provide useful information  for State  or local
governments   that   choose  to  review  or  implement  broader
classification systems.
1.3                 Guidelines Development
     The?^development  of  these  Guidelines  began  in  August
1984, an*consisted of three phases: definition, testing,  and
review.   Throughput the process, the  Office of Ground-Water
Protection  (OGWP)  worked  closely with  representatives  from
several states, EPA regions, other EPA programs,'and the U.S.
Geological Survey.

     In the  definition  phase,  key terms and concepts related
to the  classification scheme described  in  the  strategy were
analyzed  in  detail.  These key terms  and  concepts  included
irreplaceable  source  of  drinking  water  to  a  substantial
population,   ecologically  vital,   highly  vulnerable,   and
current   source  of  drinking  water.    Several  alternative
options for defining each  term were drawn up, along with data
requirements and  methodologies  for employing each.  Many  of

                             1-2       .

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the  alternative  options  were derived from approaches used by
other  EPA,  State, and local programs to address  similar or
related concepts.  Each approach was examined with respect to
the  following:

     •         Adaptability  with  statutes,  other  programs,
               and with the overall intent of the Strategy;

     •         Flexibility  for   accommodating  State-  and
               region-specific characteristics or concerns;

     •         Arbitrariness; and

     •         Potential   difficulties   or   complexities  in
               implementation.

     The next phase involved the preparation of detailed test
case studies.   The information acquired  from  this phase led
to refinements of the classification procedures.

     Finally, the  project focused on review and revision of
several  drafts.    A  Final  Draft  was   released for  public
comment in  December 1986.   The public comments received were
considered  in developing these Final Guidelines.
1.4          Organization of Guidelines Document
     Chapter  One  introduces EPA's  Ground-Water  Protection
Strategy  and discusses  the  purpose and development  of  the
classification Guidelines.   Chapter  Two provides an overview
of  the  classification  system  and  general  classification
procedures.    The  remaining chapters   focus  on  individual
aspects of the classification system.  Chapter Three contains
information  about  the Classification Review Area,  including
its  purpose,  the  determination  of  the basic 2-mile  radius
review area,  and the factors pertaining to  its  expansion or
subdivision.   Chapters  Four, Five, and  Six  focus  on Classes
I, II, and III respectively.  Each  chapter  contains a basic
review-of  the class  definition,  as  well as a discussion of
key terms  and concepts pertinent  to  the class.   In each case
the  classification  decision   process  is  presented  and
discussed  in detail.   In addition,  various techniques  and
background information that  nay  be helpful  in arriving at a
classification decision are also presented*

     A glossary  and  a  series of appendices follow Chapter
Six.   Appendix A contains information supplemental to Chapter
Three,  including the technical basis  for the 2-mile  radius
Classification Review Area as well as detailed procedures for

                             1-3

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determining  expanded or  subdivided review  area  dimensions.
Appendices B  and C provide supplemental  information  for the
non-economic  aspects  of class I and  Class  II (Chapters Four
and  Six).    Appendix D provides  guidance  for applying the
common aspects of the Class I and Class II economic tests.
                             1-4

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                            CHAPTER TWO

OVERVIEW OF  THE  GROUND-WATER CLASSIFICATION SYSTEM AND PROCESS
     The  three basic ground-water classes established in the
 1984 EPA  Ground-Water Protection Strategy, which represent a
 hierarchy of ground-water resource value  to  society,  are as
 follows:

     •  Class I -  Special Ground Waters

     •  Class II - Current and Potential  Sources of Drinkinqr
        Water and  Water Having Other Beneficial Uses

     e  Class III  -  Ground Water  Not a  Potential  Source of
        Drinking Water and of Limited  Beneficial Use


     The  classification  system is, in general,  based on the
 principle that drinking water is  the highest beneficial use
 of  the resource.   All  drinking-water  sources would  fall
within  Class I or Class II.

     Ground  water is used in  other beneficial applications,
 such as manufacturing, electric-power  generation,  livestock
production,  irrigation,  and ecosystem  support.   Class  I or
Class II  ground waters are compatible with such applications,
 in that water of  a quality suitable for drinking will also be
of suitable  quality to serve as  a raw-water  source for most
other beneficial  uses.   Class I  does include a  special non-
drinking-water component for ecologically vital ground water.
Class III ground  waters,  although not potential  sources of
drinking water, may be of limited beneficial use, such as for
industrial process cooling water.

     Some)  ground-water  classification  systems,   generally
termed  anticipatory  classification systems,  classify and map
aquifer*  or  aquifer portions  in  advance of management or
 remediation  decisions.  Although the criteria and concepts in
EPA's system can  be used for such anticipatory classifica-
tion, EPA's  system is primarily designed for classifying the
ground  water  in  the vicinity  of  a  particular facility or
 activity  as  appropriate within  a  given  regulatory program.
 In   this  site-by-site   classification  approach,   the
classification criteria are  applied on the basis of informa-
tion collected in a review area,  referred to  as  -the Clas-
sification Review Area, around the site or activity.

     This  chapter provides  an overview  of the EPA ground-
water  classification  system,   each  component  of  which  is
discussed in more  detail in subsequent chapters.

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2 .1    Ground-Water Classes
     As   previously   mentioned,   the  EPA   Ground-Water
Classification  System  consists  of three major classes.  Two
of  these  classes are further differentiated  into  subclasses,
allowing  for the  refinement  in the hierarchy of  recognized
resource  values (Figure 2-1).   Key  terms  and concepts  define
the classes and subclasses.
2.1.1   Class I - Special Ground Waters	


       Class  I ground waters  are defined  as  resources  of
unusually  high value.   They are  highly vulnerable to  con-
tamination  and  are  (1)  irreplaceable  sources  of  drinking
water  to  substantial  populations and/or  (2)   ecologically
vital.     Ground   water  that   is  highly  vulnerable  to
contamination is characterized by a relatively high potential
for contaminants to enter and/or to be transported within the
ground-water flow system.  The number of Class I  designations
is expected to be small.

     Ground  water  may  be  considered  irreplaceable   to  a
substantial population if alternative water-supply sources of
comparable  quality  and  quantity  are  beyond  a  reasonable
transport  distance,  would  be  economically infeasible  to
develop,  or are precluded  from delivery  (or would be  very
difficult to deliver) because of institutional constraints.

     Ground water may be considered ecologically vital  if it
supplies a  sensitive ecological system located  in  a ground-
water  discharge area that  supports  a  unique   habitat.    A
unique habitat  is defined to include habitats for endangered
or  threatened  species that  are listed or  formally proposed
for  listing  pursuant  to  the   Endangered  Species  Act  (as
amended  in  1982),  as  well as  certain types  of  Federally
managed and protected lands.

       A  more  detailed  explanation of Class I  concepts and
procedures is provided in Chapter Four.

2.1.2Class II - Current and Potential sources  of Drinking
       Water and Water Having other Beneficial Uses	
     All non-Class  I ground water currently used,  or poten-
tially available, as a source of drinking water and for other
beneficial use  is included in this  category,  whether or not

                               2-2

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                    FIGURE  2-1

      SUMMARY OF GROUND-WATER  CLASSES
CLASS
          KEY TERMS
                     HIGHLY VULNERABLE
                        AND EITHER
                     IRREPLACEABLE TO
                 SUBSTANTIAL POPULATIONS
                           SB.
                    ECOLOGICALLY VITAL
 IIA
       CURRENT SOURCE Of
        DRINKING WATER
 I1B
     POTENTIAL SOURCE OF
        DRINKING WATER
 IIIA
              NOT A SOURCE OF DftlNKINO WATER
            INT—MEDIATE TO HIGH INTERCONNECTION
            A*   OPOOMG/L TDS OR UNTREATA3LE
                  . SOURCE OF DRINKING WATER
                  E TO INSUFFICIENT YIELD
UIB
NOT A SOURCE OF DRINKING WATER
     LOW INTERCONNECTION
     MGA. TOS OR UNTREATABLE

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it  is  particularly vulnerable to  contamination.   This class
is  divided  into two subclasses:   current sources of drinking
water  (Subclass IIA), and potential sources of drinking water
(Subclass IIB).

     The  concept of  a current  source  of drinking water  is
rather broad  by intent.  Only a portion  of  the ground water
in  the Classification Review Area must supply drinking water.
Ground water  is considered a current source of drinking water
under  two conditions:   (1)  one or more  operating drinking-
water  wells  (or springs used as sources  of  drinking  water);
or  (2)  a water-supply  reservoir watershed (or portion  of  a
water-supply  reservoir watershed),  designated  for  water-
quality protection  by either state or local  government, oust
be  present  within  the  Classification  Review Area.   In some
circumstances,  intakes on  surface water  (used  for drinking
water supply) may also  warrant a Class IIA determination.

     A potential  source of drinking water ie .one capable of
yielding  a  quantity  of drinking water  to a well  or spring
sufficient for  the  minimum needs of an average-size family.
Drinking  water is  defined  as water with a  tptal-dissolved-
solids (TDS)  concentration of less than 10,000 milligrams per
liter  (mg/L)  that can  be used  for drinking  purposes without
first being treated,  or that can be rendered drinkable after
being  treated  by  methods  reasonably employed in a public
water-supply  system.   All around waters are  presumed to meet
both  the  yield  and   quality   criteria  for  a  current  or
potential source  of drinking water unless a successful Claas
III demonstration is performed.

     Class  II ground  waters constitute the majority of the
nation's ground-water resources  that may be affected by human
activity.  Class  II ground waters will generally receive the
very high level  of protection  that represents the baseline
degree of protection which is the standard for EPA programs.
The  procedures  for  making  a  Class  II determination  are
discussed in  greater detail  in Chapter Five.
2.1.3  CXlM III - Ground Water Not a Potential Source of
	Drinking Water and of Limited Beneficial Use	


     Ground waters that are saline, or otherwise contaminated
beyond  levels  that  would permit  their  use for  drinking or
other beneficial purposes,  are in this class.   These include
ground waters which  (1)  have & TDS concentration equal to or
greater  than 10,000 mg/L,  or  (2)  are  so contaminated by
naturally occurring  conditions,  or by the  effects of broad-
scale human activity (unrelated to a specific activity) that
they cannot be  cleaned up using treatment methods reasonably
employed in public water-supply systems.  In addition, Class

                               2-4

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 Ill encompasses  ground  waters in  those rare  settings   (3)
 where  yields are  insufficient  to meet the minimum needs of an
 average household.

     Two tests are  provided to assist  in determining Class
 III treatability.    The  first  test,  referred  to  as  the
 reference  technology test,  is  a screening tool which compares
 the treatment  scheme  needed   to  treat  contaminated  ground
 water   in  the  area   surrounding a  facility, . to  a list  of
 technologies which  appear* relevant  for  public water-supply
 treatment.   If  none  is  appropriate,  then  the ground water may
 be  technically untreatable,  pending  economic  analysis.  The
 second  treatability  test,   referred  to  as  the  economic
 untreatability  test,   is  applied  to  determine   whether
 treatment  of the water  for a  hypothetical  user population
 would  be  economically feasible.    Both  of these  tests  are
 described  in more detail  in  Chapter  Six.

     Class  III is subcategorized  primarily on  the basis of
 the degree  of  interconnection with adjacent  ground-water
 units  or surface  waters.  Subclass IIIA ground waters  have an
 intermediate degree   of interconnection  to  adjacent  ground-
 water  units  and/or  are interconnected with  surface  waters.
 As  a  result, they may  be contributing to the degradation of
 the adjacent waters.  Class  IIIA ground waters may be  managed
 at  a level similar to a level  at which Class II ground waters
 are managed,  depending  upon  the  potential   for  producing
 adverse effects on  the quality of  adjacent waters.   In ad-
 dition,  Subclass  IIIA encompasses all ground waters  from low-
 yield  settings  unless Class I  or Class II criteria have been
 demonstrated.

     Subclass IIIB ground waters are characterized by a low
 degree  of  interconnection  to  adjacent   ground-water units
 within  the  Classification Review Area.   These  ground waters
 are naturally isolated  from  sources  of drinking water  in such
 a way that there  is  little potential for  producing additional
 adverse  effects on  human health and  the environment.  They
 have  low  resource   values  outside  of mining,  oil and  gas
 recovery* or waste disposal.

     Detailed information concerning Class III determinations
 as  well as hypothetical examples are provided in Chapter Six.
2.2    General Classification Procedures



    'This  section  provides   guidance  for  initiating  the
classification process.  An outline of general classification
procedures  is given  in Figure  2-2.    A likely  sequence  of
classification  steps,  as well  as alternative  sequences  are

                               2-5

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                                                   FIGURE 2-2

                           SCHEMATIC  CHART OF GENERAL CLASSIFICATION PROCEDURES
                                                    DELINEATION OF
                                              CLASSIFICATION REVIEW AREA
                                                BASIC DATA COLLECTION
                               •
           SOURCE OF OMINKINO WATCH OR ECOLOGICALLY VITAL AREAS
I
Ot





CLAS<
MIONLV
VULNERABLE
ECOLOGICALLY
VITAL AREAS



I 1 »
/--
^


t
1
•ROCE
-"N
^


s
OURC
HIONLY
VULNERABLE
IRREPLACEABLE
SOURCE OF
ORINNINO WATER
TO A SUBSTAN-
TIAL POPULATION









	 NO-*-




CLASS II
PROCEDURES


YES
                                                                                  o
                                                                                         NOT A  S
     >URCE OF
                                                                                          DRINKINO WATE'ft
                                                                                                1
 CLASS  111
PROCEDURES
                                                                                                VI

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 discussed  in this  section,    cross  references  are  made to
 those  chapters  that  contain  more  detail  on  a  specific
 classification  procedure.   Sources  of infornation  and data
 needed   for   classification   are   discussed,   generally,  in
 Section  2.3.

     The first  step  in  EPA's  site-by-site  classification
 procedure is  to  draw a 2-mile radius around the  sit* that is
 to  be  classified  —  this  is the   standard  Classification
 Review Area.  The second step is to collect basic information
 about  the  classification  Review Area concerning demography/
 local use of  ground  water,  general hydrogeologic conditions,
 and  the presence  of  ecologically vital  areas  and  surface
 waters.  The  information  collected may indicate that expan-
 sion   or  subdivision  of   the   standard  2-mile   radius
 Classification  Review  Area  would be appropriate.    If the
 Classification Review Area is expanded, additional  data about
 the expanded portion is normally gathered.  If subdivision is
 contemplated,   the   classifier   will   typically   collect
 additional hydrogeologic information to support a subdivision
 demonstration.   Detailed procedures  for  determining the size
 and  configuration  of  the  Classification Review  Area,
 including expansion and subdivision,  are discussed  in Chapter
 Three.

     The third  step in the  classification procedure  is to
 assign the ground  water to a particular  class,  based on the
 data  collected.    A  classifier   beginning this  step  will
 typically face  two  choices:   (1) to assess  the  likelihood
 that the ground water  is a source  of  drinking water or
 ecologically  vital  (Class I  or II),  or  (2)  to  assess the
 likelihood that  the ground water is  not a source of drinking
water (Class  III).   (This procedure  is illustrated in Figure
 2-3.)   Preliminary  information should indicate  which of the
two choices  is  most likely.   If  the classifier  chooses to
begin the analysis with an initial look at the likelihood of
 a  Class  III  determination,  it   is  still necessary  to
 demonstrate  that  the   ground water  is   not  a current  or
potential source of drinking water  or  ecologically vital.
 For  example,  while   the  ground  water   may be   initially
 considered  contaminated  and  untreatable,   if  a  private
 drinking water well is present in the review area,  the ground
 water should  be  assigned to Class  II. Most classifiers will
 find it  aost efficient to  begin with  an  analysis  of the
 likelihood of a  Class I determination,  and then  review the
 possibility of  a  Class III  determination if there  are no
wells,  drinking-water reservoirs or  springs,  and no ecologi-
 cally vital areas within the Classification Review Area.

     The classification procedure is an  iterative  process,
with each  iteration building upon  the   previous  one.   For
example,  if the  classifier  has gone  through  the classifica-
tion process  and determined  that  the ground  water will most
likely  be Class  I, it  may  be necessary to go  back to Step 2

                               2-7

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and  collect additional  information  to ensure that  the most
appropriate  class  decision is  made.    This process can  be
repeated until  an accurate and appropriate classification is
obtained.
2.3            Collection of Basic Information
     Basic  inforaational  needs   for  classification  are
outlined  in  this  section.    More  detailed information  is
provided  in Chapter Three  (The  Classification  Review Area),
as well as in subsequent chapters,  which discuss each of the
classes  in turn.    The collection  of basic information  is
meant  to  reflect  an approach to classification  that begins
simply and directly.   It  will typically include  a  well and
reservoir   survey,  demographic   information,   basic  water-
quality data, and  identification of ecologically vital areas.
Regional  and  local  hydrogeologic  data  will  normally  be
gathered   if   an  interconnection  analysis  is  undertaken.
Otherwise,  a general  description  of  the  regional  geology,
ge©morphology,   and  hydrogeology  would  normally  suffice.
Again, the emphasis is on available  information rather than
on detailed in-field analyses.  A more rigorous analysis is,
in general, necessary to support a Class III determination.

     Well information may be obtained from water authorities,
utilities,  public-health  agencies,  regulatory  agencies
permitting  well  drilling, well  drillers,  or other  State  or
local  entities.    Basic  water-quality  information is usually
available  from local health agencies,  other State and local
agencies,  and national data bases  such as  STORET.   In some
cases, university  research departments may be able to supply
needed data.   Assistance  in  identifying  ecologically vital
areas  may  be  obtained  from  the  U.S.  Fish  and  Wildlife
Service.   Regional  and/or local hydrogeologic  and geologic
information may  be available from county/regional reports of
the U.S. "iiB& State geologic surveys.  Demographic information
can be obtained  from the U.S.  Census Bureau.
                               2-8

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                        CHAPTER THREE

                THE CLASSIFICATION- REVIEW AREA
3.1       Purpose of the classification Review Area
     Classifying  ground water  involves  applying the  clas-
sification  system's  criteria to  a  segment of  ground water.
In some systems, generally termed anticipatory classification
systems, criteria are applied on a regional or aquifer basis,
and  class  determinations are mapped in  advance  of specific
management  decisions.   Although  the  criteria  and concepts in
EPA's  system can be  used for such  anticipatory classifica-
tion,  EPA's system  is primarily  designed for  classifying the
ground  water in  the vicinity  of a particular  facility or
activity as appropriate within  a given  regulatory program.
Thus,  this  first step  in EFA's  site-by-site classification
procedure is  to determine the size  and  configuration of the
Classification  Review  Area  around  the  site  to which  the
classification criteria will be  applied.

     EPA believes that  it is appropriate to  look at a broad
area  for  characterizing  the  ground  water  which  may  be
affected by the activity(ies) at a  particular  site.   Within
the  Classification   Review  Area,  basic  information  is
collected concerning  hydrogeologic conditions,  public-supply
wells,  populated areas not served by public supply, wetlands,
and  surfaeet waters,  as  described   in  Section  3.5 of  this
chapter.  Through applying the use,  value,  and vulnerability
criteria, a ground-water class  determination is  aade  which
may  be  used  as  a  factor  in  determining   what  specific
regulatory  action  or decision is appropriate for the  site.
However', it should be  noted that a  classification decision
will apply  only to the  specific  facility or site in question
and for which the Classification Review Area was drawn.

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3.2       Determining the Classification Review Area
3.2.1     Introduction
     As  a  first step, an 'initial  Classification  Review  Area
will most often be determined by drawing a 2-mile radius  from
the facility or activity for which the class determination is
being  made.    Some  EPA  programs  utilize  a  somewhat  larger
review  area,  the  use   of  which   is   covered  by   the
Implementation Policy Statement.

     A Classification Review Area with a 2-mile radius around
a proposed facility  is shown  on Figure 3-1.   The site of the
facility  is  approximately  500  feet  in  dimeter.    Water
supplies in  the Classification Review Area  i.-";lude  a public
water-supply  system  well  and  a  densely  settled  area  of
private  wells.    A  river with a  wetland runs  through  the
review area.  Each of these facts may bear on the decision of
the class of ground water.

     EPA selected 2-miles as  a typically  appropriate radius
size  for the  Classification Review  Area  after  analysis of
three  sources  of  data that provided  insight into the length
of the  flow  path over which  high degrees  of interconnection
occur and  indicated  distances contaminants could be expected
to move in problem concentrations should they be accidentally
introduced into the ground-water system.  The sources of data
examined were as  follows:


     •  A survey  of contaminant plumes from investigations of
        existing  spills, leaXs, and discharges.

     •  A  survey  of  the distances to  downgradient surface
        waters from hazardous-waste facilities.

     e  calculations  of  the  distances from which  pumping
        walls draw ground water under different hydrogeologic
        .conditions.                             .
Analyses  of  the  data .indicate that  in  95  percent of  the
cases, the lengths and distances of contaminated ground-water
plumes  from  hazardous   waste  facilities  to  downgradient
surface  waters likely  to  be  discharge points  for shallow
ground water are less than 2 miles.  A detailed discussion of
these data  and  their interpretation  is  provided in Appendix
A.

                             3-2

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                                             FIGURE 3-1

                              HYPOTHETICAL CLASSIFICATION REVIEW AREA
                           SHOWING POTENTIAL CLASS DETERMINING  FACTORS
LJ
I

     —vvirvvirirviri^Jiririrwiririririr



-------
     Under  certain hydrogeoiogic conditions, however,  expan-
sion  or  subdivision  of  the  2-nile  radius  Classification
Review Area may be appropriate.  Sections 3.3 and  3.4 provide
guidance  on  the  types  of  situations  where   expansion or
subdivision  of   the   Classification  Review  Area  nay  be
warranted,   as   well  as   procedures  for  making  these
adjustments.   Basic data  needs for the characterization of
the  Classification Review Area  prior  to application of the
classification   criteria  are  discussed  in  Section   3.5.
Guidance  for  drawing  the   Classification  Review  Area
boundaries  from  various  sized,  regularly  and  irregularly
shaped facilities  is given in Section 3.6.
3.3     Expansion of the Classification Review Area
3.3.1   Introduct ion	


     As  mentioned  previously,   under  some   hydrogeoiogic
conditions,  a  2-mile radius review area may be insufficient
for characterizing  the ground water that may potentially  be
affected  by  a  facility.    In  areas  of  very  high  flow
velocities  that occur  over distances  greater  than 2  miles,
there  is a potential  for activity-related contaminants  to
move beyond a 2-mile radius in a relatively short time  frame,
especially  under the  influence  of large-scale  ground-water
withdrawals.     -hough it is expected  that the  2-mile  review
area  will   be  . :ficient in extent to accommodate the  vast
majority of classification decisions,   this  section presents
guidance  for identifying  those  unusual situations where  an
expanded  review  area  nay  be  appropriate.    In  addition,
general procedures  are suggested to establish the dimensions
of the expanded Classification Review Area based on available
informatiflto concerning hydrogeoiogic characteristics.  . (Note
that semi-SPA programs  routinely use • somewhat  larger  review
area; this* section  addresses situations where a still  larger
area might  be  warranted due to hydrogeoiogic conditions.)   A
detailed discussion of Classification  Review Area expansion
is presented in Appendix A.2.
                             3-4

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 3.3.2    Determining Whether Expansion  Is Warranted          J


     Deciding  whether  to expand  the  Classification Review
 Area  is a judgment of the classifier, made on a case-by-case
 basis.   As  a general'rule-of-thumb, expansion is intended for
 those   situations  likely  to  result   in  the  transport  of
 contaminants  beyond  2 miles during a  period of  10 years or
 less.   This translates to cases where  ground-water velocities
 exceeding 1,000 feet/year (ft/yr) over a substantial distance
 are  prob-able.   Ten  years  is  assumed to  be a  reasonably
 conservative tine period for controlling contaminant.(s) after
 the contaminants have been detected.   Very few settings have
 ground-water migration exceeding a distance of 2 miles within
 a  10-year  period;  therefore,  Classification  Review  Area
 expansion is likely to be the exception rather than the rule.


     It   is not   necessary  to  have  precise  ground-water
 velocity  data  for  the  review area  in order  to  decide  if
 expansion is  appropriate; however where possible,  such data
 should  be examined.    It is anticipated  that investigations
 pertaining  to  RCRA   land-disposal  facilities  or  Superfund
 ground-water contamination sites will, as a  routine matter,
 already  incorporate  the  information   necessary to  determine
 ground-water velocities.

     Other  situations  will  likely  not  be   investigated  in
 sufficient  detail  to gauge ground-water velocity;  a general
 screening procedure  can  be  employed  in  the  absence  of
velocity  information.  """ This  procedure  involves  matching
hydrogeologic conditions 'in the 2-mile review area to generic
hydrogeologic  settings, where  high  velocities  are  very
commonly  found.  The  following sections provide a discussion
of  high-velocity  settings  for  the  classifier's  reference.
Note that there may  be specific high-velocity settings known
to regional or State authorities that  are not discussed here.

High-Velocity Hvdroaeoloav

     Hydrogeologic settings can  generally  be classified into
 two  type*  of  ground-water  flow regimes,  Darcian and  non-
 Dare ian.  The identification of the dominant flow regime at a
 specific  site  can be  useful  in evaluating the need to expand
the Classification Review Area.

     Darcian  flow refers to  the  movement   of  water  under
conditions  where  Darcy's law  applies.    Typically,  these
conditions  involve   intergranular,   laminar  flow,  without
turbulence.   Darcy's law states that the velocity of flow, v,
 is equal  to the product of a  factor called hydraulic conduc-
tivity,  X,  and the  hydraulic  gradient (e.g.,  slope  of  the
water table in  an unconfined aquifer)  divided by the aquifer

                             3-5

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porosity.   (These terss are  defined  in  the  glossary.)   When
turbulent  flow  occurs,  as  in water moving in a pipe,  Darcy's
law  does not  apply for determining  flow velocities.   Gen-
erally, the non-Darcian flow  settings have higher velocities,
due  to the pipe-like  flow,  than Darcian  flow  settings  and,
for this reason,  are strong candidates for an expanded review
area.

     Non-Darcian   flow  occurs  in  geologic  settings  where
secondary  porosity dominates the ground-water  flow  regime.
Secondary  porosity  refers  to relatively large  continuous
openings,  fractures,  or  tunnels  (i.e.,  the pipe-like  .fea-
tures)  that  transport  water.    Intergranular  flow  moving
according  to   Darcy's   law  contributes  a  proportionately
insignificant volume  of flow in these settings.   Examples of
non-Darcian  flow  settings include  mature karst,  fractured
rock,  and  extrusive  igneous rocks  (basaltic  lava).    For
hydrogeologic  settings  with  predominantly non-Darcian flow,
it  is  likely  that  the  flow velocity  is  so great  that
Classification Review Area expansion is appropriate.

     In  Darcian  settings,  it will  be  unlikely  that  flow
velocities as  high as  1 mile a year will occur except over
very short distances  not representative of flow throughout a
ground-water unit.  However,  velocities in the range of 1,000
ft/yr, although rare, can be  expected and would be supportive
of an  expanded Classification Review Area.   Settings where
Darcian  flow  predominates  and  high  velocities  frequently
occur  include  alluvial basins,   other  alluvial  materials,
coastal  plains,   and  glacial  outwash  settings,  that  is,
aquifers  that  are primarily composed  of  coarse  sand  and
gravel.

     Descriptions  of high-velocity hydrogeologic  settings,
Darcian and non-Darcian, and where these settings are likely
to occur are  provided  in the  following subsections.   The
likelihood of encountering high-velocity flow regimes can.be
roughly associated with selected ground-water regions.  Heath
(1984) developed  a map of ground-water  regions  (Figure 3-2)
and  summarized  the  hydrogeologic characteristics  of  each
region.  .The) general  hydrogeologic conditions characteristic
of each  cj£ the  regions  can be used to preliminarily evaluate
the  likelihood  of encountering a high-velocity ground-water
regime at  a- specific  site.  Information from the review area
should .be  relied on  for   the  final  judgment  concerning
expansion.

Non-Dareian Settings.    Non-Darcian settings can be  grouped
into three general categories:   karst,  fractured  rock,  and
extrusive igneous rocks (e.g., basalts).  These settings are
very common in some regions and are expected to  account for a
significant,  but not  dominant,  portion of   hydrogeologic
settings.  For judging review area expansion, it is important
to   determine   if  the   subject  ground-water  unit  is

                              3-6

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                  FIGURE 3-2




GROUND WATER REGIONS OF THE U.S. (Heath 1984)

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predominately   non-Darcian   flow.     If   non-Darcian   flow
contributes  to  a  minor  part  of the  flow  in  the  subject
ground-water unit,  the setting should be treated as a Oarcian
flow setting with respect to review area expansion.

     Karst  settings that are  most likely candidates for  an
expanded  Classification  Review  Area  are  those  where the
subject ground  water is  relatively shallow  (
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Jcr vn  to be  high  yielding and  are primarily used  for non-
ce,--unity domestic supply.

     Fractured-rock  settings  are   most  prevalent   in  the
following ground-water regions (Heath, 1984):

         Northeast and Superior Uplands.
         Piedmont and Blue Ridges.
         Western Mountain Ranges.
         Columbia Lava Plateau.
         Colorado Plateau and Wyoming Basin.
         Non-Glaciated Central Region.
         Glaciated Central Region.


     Extrusive  igneous  rocks  (s.g.,  basalts)  will  usually
have zones of high transmissivities and velocities.   They are
often  found  in  association  with sedimentary  rocks in  the
Columbia Lava Plateau Region.   These aquifers are composed of
sequences   of  basaltic  lava   flows   that  have  developed
extensive secondary porosity.   A lava  flow cools rapidly at
the surface.  As a result, brittle  crust forms  and  is broken
into   angular  fragments  by   the   continued   movement  of
underlying lava.   These  lava flows may  also have lava  tubes
that act like large-diameter pipes.   In addition,   the lava
flows  are  subject  to fracturing,  as  lava  cools,  and  the
formation of bedding joints.   The result is an earth material
with considerable  secondary  porosity  that,  when saturated,
may have a very high transmissivity.  These settings are very
common in the following ground-water regions  (Heath  1984):

     e   Columbia Lava Plateau.
     e   Hawaiian Islands.


Darcian  Settings.    Darcian-type  flow  settings where  high
ground-water flow velocities can be expected are rare and are
restricted  to  aquifers  with   relatively  high  hydraulic
conductivities  or  transmissivities.     Such  settings  are
predominated  by  coarse grain size, e.g.,  sand  and gravel,
with very  minor  inclusions  of  silt  and  clay.    Hydraulic
conductivities in  coarse-grained materials  can  sometimes be
greater  than  500   gallons  per  day  per  square   feet
(gal/day/ft2) and  have  ground-water velocities  greater than
1,000  ft/yr.    Such Darcian  settings  aay be  found in  any
region of the country.   Generally, they are found in alluvial
basins, other alluvial materials, coastal plains, and glacial
outwash settings.
                             3-9

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3.4    .   Subdivision  of  the Classification Review Area
3.4.1	Introduction	


     For  most classification determinations,  the  assumption
is that all the ground water within the Classification Review
Area  is  highly interconnected and,  therefore,  is  classified
as one unit.   Sometimes, however,  the classifier may wish to
subdivide  the  Classification   Review  Area  into  separate
ground-water  units, as  there  may  be  naturally   occurring
ground-water  bodies of  significantly different use and value
within  the   Classification  Review  Area  that  need  to  be
considered  as part of   the  decision-making  process  for  the
activity or facility involved.   These ground-water units may
be adjacent laterally  and/or vertically to one another.   The
principal  technical issue is  to what  degree the  adjacent
units are  interconnected,  that  is,  to what extent  would an
adverse  effect  on  water  quality  in  one  unit  produce  an
adverse change in  water  quality  in  the adjacent unit.   A low
degree  of  interconnection  suggests  little 'potential  for
ground-water  migration;  a high  degree suggests the  need to
consider the  impact of potential migration between  units.

     The concepts  of ground-water units and the interconnec-
tion  between adjacent  ground-water  units  are  especially
important  in Class  III  determinations,  where  degree  of
interconnection distinguishes the  subclasses  IIIA  and  IIIB
(see Chapter  Six).  Subdivision of  the  review area  may also
be appropriate  in  determining whether there is discharge to
ecologically vital  areas  for  Class  I  determinations.
Finally,   the  classifier   may  wish   to  subdivide   the
Classification  Review Area  to  permit a  more sophisticated
hydrogeologic analysis of  the potential impacts of  a facility
or activity as  a  step in determining the specific  prevention
measures or remedial action to be employed at a site.

     Subdivision   of  the  Classification  Review  Area  will
generally be  necessary  to demonstrate the  existence  of the
following types of conditions:

     •  Relative to a  specific  site, deep ground-water units
        with  Class IIIB  water are overlain at a shallow depth
        by ground-water  units with Class r or II water.

     e  The  ground-water  unit  associated  with ah  activity
        does  not  discharge  to  an  ecologically  vital  area
        present in the Classification Review Area.
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      •  Relative  to a specific site, a shallow, ground-water
        unit  with Class IIB ground  water (i.e.,  a potential
        source  of  drinking  water)  is underlain by  a deeper
        ground-water  unit with Class IIA  ground water (i.e. a
        current source  of drinking water).


      Hydrogeologists  routinely  assess   the  interconnection
between bodies of ground water for such purposes as designing
water-supply  systems,  monitoring  systems,  and  corrective
actions  to address  contaminated  water.    Where ground-water
bodies are  shown  to have low interconnection,  it is possible
to consider them separately  in assessing  their use and value.
Waters within a  ground-water unit are inferred to be highly
interconnected and,  therefore,  a  common  use and value can be
determined.

      Prevention or  cleanup  decisions for a ground-water unit
with  low  interconnection  to adjacent ground water or surface
water can be  expected to  have  no,  or very limited, impact on
the quality of the  adjacent waters.   Conversely, where there
is high  interconnection to adjacent ground  water  or surface
water, the classifier's decision should take into account the
potential impact that contamination  of one ground-water unit
(which may not itself be  of great value)  may have on higher-
quality ground-water units.

     The identification of  ground-water  units  and the evalu-
ation of  interconnection between ground-water  units  may,  in
critical  cases,  require  a  rigorous  hydrogeologic analysis.
The analysis  may be  dependent upon data collected  off-site
that  is  not part of  the readily available  information nor-
mally used  in a classification decision.   For these reasons,
subdivision is  expected -to  be  on an exception basis rather
than  a  routine  part of  classification;  EPA  will,   in most
cases, assume a  high degree  of  interconnection  within  the
Classification Review Area.

     Once ground-water units within the Classification Review
Area  have been identified,  each unit that say be affected by
an activity/facility under  review  is reviewed  according  to
the criteria  or methods  in these Guidelines.   Note  that in
the relationship between subdivision and classification:

     • -All ground  water within  a  ground-water unit  has  a
        single class designation with respect to the facility
        being considered.

     e  Boundaries  separating  waters of different  classes
        must coincide with boundaries of ground-water units.
                             3-11

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     •  Boundaries  of  the Classification Review Area do  not
        constitute  ground-water  unit boundaries unless  they
        meet the conditions for subdivision boundary (Type 1,
        2, 3, or 4 boundaries).

     •If  a   subdivision  boundary  cannot  be   acceptably
        demonstrated, then the existence of a single  ground-
        water unit should be assumed.
3.4.2	Concepts of Ground-Water Units and Interconnection


     Ground-water  units  are components  of the  ground-water
regime, which is defined as the sum total of all ground water
and  surrounding geologic media  (e.g.,  sediment and  rocks).
The  top of  the ground-water regime  would be the  uppermost
surface of  the  zone of saturation while the bottom would  be
the  base  of  significant  ground-water circulation.    Tempor-
arily  perched  water  tables within  the  vadose  zone  (see
Glossary)  would generally not  qualify as  the upper boundary
of the  regime.   The  Agency recognizes that upper  and lower
boundaries  are  sometimes  difficult  to  define  and  their
location  must  be  established based  on  the best  available
information and professional judgment.

     The ground-water  regime/ encompassed  by the Classifica-
tion 'Review Area,  can be  subdivided into mappable,  three-
dimensional, ground-water units.   These are defined as bodies
of ground water  that are  determined on  the  basis of  four
types of boundaries as described below,

     Type l:    Permanent ground-water  flow divides.   These
                flow  divides  should  be  stable  under  all
                reasonably  foreseeable  conditions,  including
                planned   manipulation  of   the   ground-water
                regime.

     Typex 2:    Extensive,   low-permeability  (non-aquifer)
                geologic units (e.g.,  thick, laterally exten-
                sive   confining  beds),  especially • where
                characterized  by  favorable  hydraulic  head
                relationships across  them  (i.e., the  direc-
                tion  and  magnitude of flow through the low-
                permeability  unit).     The  most  favorable
                hydraulic head relationship  is where  flow is
                toward .the ground-water unit to be classified
                and  the  magnitude of   the  head  difference
                 (hydraulic  gradient)   is  sufficient  to
                maintain  this* direction of  flow  under  all
                foreseeable conditions.   The integrity of the
                low-permeability  unit should  not  be  inter-
                rupted by improperly constructed or abandoned

                             3-12

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                wells,  extensive,  interconnected  fractures,
                nine tunnels, or other apertures.

     Type 3:    Permanent  fresh-water/saline-water  contacts
                (saline waters being  defined  as those waters
                with greater than 10,000 mg/L of IDS).  These
                contacts   should   be  stable  under   all
                reasonably  foreseeable  conditions,  including
                planned  manipulation  of   the  ground-water
                system.

     Type 4:    Hydraulic gradient-based boundaries  separat-
                ing  permanent  upgradient  from  permanent
                downgradient parts  of a shallow ground-water
                unit,  (uppermost  aquifer).   These  boundaries
                must   be  simulated  assuming  worst-case
                withdrawal rates in the  upgradient region.

     The  type  of  boundary  separating  ground-water  units
reflects the  degree  of interconnection between  those units.
Adjacent  ground-water  units  demarcated  on  the  basis  of
boundary  Type 2  are  considered to  have  a  low  degree  of
interconnection.   A  low  degree of  interconnection  implies  a
low  potential for  an adverse  water-quality  change in  one
ground-water  unit  to  cause  a similar  adverse change in an
adjacent   ground-water   unit  due  to  the  migration  of
contaminants.   A low degree of interconnection is expected to
be permanent,  unless  improper management  (e.g., presence of
significant  numbers   of  improperly  installed  or  abandoned
wells)   causes  the  low-permeability  flow  boundary  to  be
breached.   The lowest  degree  of  interconnection occurs where
a  Type 2  boundary separates  naturally saline  waters in  a
deeper ground-water  unit from overlying  fresh waters  (less
than  10,000   mg/L  TDS),   and the  hydraulic  gradient  (flow
direction)  across  the confining  layer  (Type 2  boundary)  is
toward the saline waters.

     Type 2  boundary  conditions  are particularly  important
for distinguishing Subclass IIIB ground-water units.   In this
regard, the Type  2  boundary criteria encompass, but are not
limited to, the vertical  interconnection criteria for Class I
injection veils pursuant  to the Underground Injection Control
program.

     Adjacent, ground-water  units  demarcated on the  basis of
boundary Type 1  (ground-water flow divide),  Type 3 (fresh-
water/saline water contact), and  Type 4  (gradient  based)  are
considered to have an intermediate degree of interconnection.
An  intermediate  degree  of  interconnection  also  implies  a
relatively low potential  for adverse water-quality changes in
one ground-water unit due to migration of contaminated waters.
from an adjacent ground-water unit.
                            3-13

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     A  high degree  of interconnection is  inferred  when the
conditions  for  a  lower  degree  of interconnection are not
demonstrated.    High  interconnection  of  ground  waters  is
assumed  to  occur within a ground-water unit and where ground
water discharges into  adjacent surface waters.  A high degree
of interconnection  implies a significant potential for cross-
contamination of waters if a component part of these settings
becomes  polluted.

     The degree  of interconnection across the boundary types
defined  here depends  on  selected  key physical  and chemical
processes governing movement of water and dissolved solute in
the   subsurface.     Under  steady-state  ground-water  flow
conditions,  the principal  mechanisms  affecting  potential
contaminant movement  across  Type 1, 3,  or 4 boundaries would
be mechanical dispersion  and chemical diffusion.  These con-
ditions  are considered by  EPA to  represent  an intermediate
degree  of  interconnection.   Under  transient  flow conditions
caused  by  pumpage  or accelerated  recharge of  fluids  within
the Classification Review Area, the potential exists to spat-
ially  displace  any of  these  three  boundari-ts;    For  this
reason   EPA  believes  that  foreseeable  changes in  aquifer
stresses and increased ground-water use in the Classification
Review  Area should  be considered  in determining  the perma-
nence (i.e., location  over time)  of such boundaries.

     The primary mechanism for contaminant transport across a
Type 2 boundary  is the physical movement of ground water into
or  from  the low-permeability  geologic  unit.   The  Agency
recognizes  that the  physical  and chemical  processes  that
control  fluid  and solute  transport through low-permeability
non-aquifers is  not as well understood as it is  for aquifers.
However, for the purposes of assessing  the degree of inter-
connection, it is assumed that the  flow rate of  water through
the  non-aquifer  is very  small  relative  to the  flow rates
through  adjacent aquifers.

     Appendix A.2 presents further guidance  and examples on
how boundaries between ground-water units are identified.
3.5       Characterizing the classification Review Area
     After  the  Classification Review  Area  dimensions  have
been determined,   the  first  step in making a classification
decision  involves  collecting  basic  information about  the
Classification  Review  Area.     This  basic  information  on
demography,  the  presence of  ecologically vital  areas,  the
local  use   of   ground  water  for  water  supply,  and  the
hydrogeology  will  serve as  the   starting  point  for  the

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 classification   process,  pointing  the  way  to  where  more
 detailed  data collection or analysis nay be needed to arrive
 at a class determination.   At this stage,  the emphasis is on
 collecting the  most  current,  best  data that  is  readily
 available.

      The  basic data needs are keyed to the principal distinc-
 tions between  the  ground-water  classes.   Use  and  value
 distinctions  are based  on  the  extent  to which the  ground
 water is  now or could be  used in the future as  a  source of
 drinking-water  supply,   and  if  contamination  of the  ground
 water could affect  ecologically  vital areas.   Other distinc-
 tions between classes are based on hydrogeologic considera-
 tions,  such as  vulnerability  and degree  of  interconnection
 with  adjacent ground water and surface water.

      Collection  of the btsic data needed to characterize the
 Classification  Review Area  is  discussed  below,  along  with
 suggestions  for possible  sources of data.   For some  deci-
 sions, the level of detail  at this  stage  will  be sufficient
 to make a class  determination;  for other decisions,  or where
 readily  available  information  is  inadequate  for  making  a
 class distinction, more detailed data collection and analysis
 may  be needed.    Subsequent chapters  discuss  each of  the
 classes and provide further guidance on informational  needs
 related to each respective class.

      It is recommended  that the sources  of  all  information
 collected be recorded for future reference.  When information
 is not readily available,  noting this fact in the file along
 with  what avenues were pursued,  may avoid retracing steps at
 a later time.

 Well  Survey

     A  well  survey  to  identify  the presence of  drinking
 water-supply wells, public and/or private, in the Classifica-
 tion  Review Area  is  needed to  determine  local  use of  the
 ground water.

      Public water-supply systems are defined under  the  Safe
 Drinking  Water. Act  a* those serving more  than  25 person* or
 with  more than  15 service connections.  In the well survey,
 the  location  of any  existing  public water-supply wells  'and
 their puapage capacity should  be identified.   Information on
 well  depth and  screened  intervals may  also  prove  useful,
 particularly  if  more  detailed hydrogeologic analysis of  the
 area  is to be undertaken*

     A detailed inventory of private residential wells is not
necessary.  One  method  for  estimating the number of private
wells  is   to  obtain  census  data  regarding the  density  of
 settlement  in the  area.   The  area  served by public-water
 systems (surface or ground)  is delineated  and  it is assumed

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that  the  remaining  hones  have  private  wells.    General
characteristics  of  private  veils,  such as depth and screened
intervals, nay also be useful, if available.

     Well information may be obtained from water authorities,
public-health  agencies,  regulatory agencies  permitting  well
drilling, well drillers, or other State or local entities.

Water-Supply Reservoirs and Surface Water Intakes

     Water-supply reservoir watersheds  designated for water-
quality protection are specifically recognized in the ground-
water  classification  system  and  should  be identified  and
described if any are located within the Classification Review
Area.   The  location of  surface-water  intakes  for drinking
supply   purposes   will  also   be   relevant  under  certain
conditions.   Again,  State and local  agencies should be  able
to  provide  the information.    A  more detailed  discussion
concerning   the  identification   of  protected  water-supply
reservoirs is presented in Chapter Five.

Demography

     Information on  populations  served  by public and private
wells  will  be   needed  if  it  is  apparent  that substantial
populations may  be  involved,  a  finding that could  lead  to a
Class  I decision.    A first-cut  approximation  for public-
supply veils  in the area can  be made by  dividing  the total
pumpage capacity by  the typical  per capita consumption rates
for the region.  Estimates  of  the number of private wells  in
densely settled  areas within the Classification Review  Area
will also be necessary.  Densely settled areas can be located
on U.S. Census  Bureau maps.   Detailed  procedures for deter-
mination of  substantial population are provided in Chapter
Four.

Ecologically Vital Areas

     Ecologically vital arsas are  also recognized  by EPA's
classification  system  and are defined  as  those ground-water
discharge^ areas that  provide  habitat  for  threatened  or
endangers** species  (pursuant  to the  Endangered Species  Act)
or discBivge areas  that are Federally managed for ecological
value.  It any  areas that provide  habitat for threatened  or
endangered  species  are  located within  the  Classification
Review  Area,  candidate  discharge  areas   such- as  springs,
streams,  caves, lakes,  wetlands,  estuaries,  coastlines,
embayments,  and piayas,  should be identified.    (Further
analysis of  the hydrogeology may be needed  to prove actual
ground-water  discharge;  see  Chapter Four.)    The Regional
Office of  the U.S.  Fish  and wildlife.  Service  and  the State
Endangered Species  coordinator  or  Heritage Program adminis-
trator  are  two  sources for  information  regarding  unique
habitats and/or  endangered or threatened species.  A detailed

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 discuss!   on methods  to  identify ecologically vital areas is
 presents  in  Section  4.3.    Information  about  Federal lands
 may alsc ce  obtained  from  Federal land-management agencies,
 such as che  National  Park  Service,  U.S.  Forest Service,  and
 Bureau of  Land Management.   The presence of Federal lands is
 indicated  on most  State  and  county  road maps  and  U.S.
 Geological Survey quadrangle  sheets.

 Hydrocreologic Data

      Information  on the  hydrogeology in  the ' Classification
 Review Area  is pertinent  to  class  distinctions  based  on
 vulnerability (Class  I)  and degree  of  interconnection  to
 adjacent ground water or  surface water  (Class  III).    In
 characterizing the  hydrogeology,  for these purposes,  general
 data needs may include the  following:


      e   Regional geology  (e.g., surficial geologic maps).

      e   Depth to water/thickness of vadose zone.

      e   Regional ground-water recharge rates.

      e   Aquifer and ground-water flow system
          characteristics.

      e   Soil and vadose zone characteristics.

      e   Topography (slope).

      •   Landscape position/land form.

      •   Location of surface-water features.
      This  information  may  likely   be  obtained   from
county/regional  reports and  also State  geologic  surveys or
the  U.S.  Geological Survey.   The best available  sources of
published  hydrologic/geologic   information  are   the  U.S.
Geological  Survey  publications,  State   geological  surveys,
scientific books and journals, and U.S.  Department of Agri-
culture county soil surveys.  Data supporting facility permit
application*,  (e.g.,  for  RCRA-related  activities),  Clean
Water  Act  Section 208  studies,  as  well   as  Environmental
Impact Statements,  nay also be  useful.   The U.S.  Geological
Survey District offices are a primary source of area-specific
data and information.

     The U.S.  Geological Survey has two- subdivisions  which
nay  supply useful  information.   These  are the  Rydrelogie
Information Unit  and  the  Geologic Inquiries Group.   They are
described below.
                             3-17

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      1.  The Hvdroloeric Information Unit

      The  Hydrologic  Information  Unit answers  general  ques-
tions on  hydrology,  water as  a  resource,  and  hydrologic
mapping,  as well as  on the products,  projects, and services
of the Water Resource Division.  Inquiries should be directed
to the following:

               The Hydrologic Inquiries Group
               United States Geological Survey
               419 National Center
               Reston, VA   22092
                (703)  648-6818
     2,  The Geologic  Inquiries Group

     The Geologic  Inquiries Group is the primary information
group of the geologic  division of the U.S. Geological Survey.
The geologic Inquiries Group provides information and answers
inquiries  on  the  activities  and products  of the  geologic
division.   Questions concerning all  aspects of geology, such
as geology of specific  areas,  geochemistry,  geophysics,  and
other  geoscientific  disciplines,  as  well  as geologic  map
coverage should be directed to the following:

               Geologic  Inquiries Group
               United  States Geological Survey
               907 National Center
               Reston, VA  22092
               (703) 648-4383


     The  hydrogeologic  information  collected  during  this
characterization  phase  may  suggest  that  there  could  be
potential  impacts  in  an area  larger  than the usual  2-mile
radius  (or  other program-specific radius) of the Classifica-
tion Review Area.    Section 3.3.2 of this  chapter describes
those  unique; hydrogeologic  conditions  of very high ground-
water flair-velocities  where an expanded Classification Review
Area mayf.tfc warranted and provides guidance  on  determining
the size o* the expansion.

     Similarly, this review may indicate a  need  to evaluate
the  interconnection of  ground water  with  adjacent ground-
water units and with surface water,  such as when a Class III
determination  is  considered possible or when subdivision of
the  Classification  Review  Area  into  ground-water  units is
planned   (e.g.,  to  address  multiple,  layered  aquifers).
Section 3.4.2 of this  chapter describes the information needs
and considerations involved in assessing interconnection to
adjacent water and  in subdividing the Classification Review
Area into ground-water units.

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3.6       Location of the Classification Review Area Boundary
          Relative to the Facility/Activity Boundary
     The  facilities  and  activities subject  to  EPA  actions
range in  surface area from very small  (under  1 acre)  to  very
large (over 40 acres).  In some cases,  there  say be-multiple
activities located at  the sane facility  for  which a  single
class  determination   is  desired.    There  may  also  be  an
unusually shaped unit or  condition, such  as a pipeline or  an
elongated  plume.   Drawing the  limits of  a Classification
Review Area  a given distance  away from  a  facility/activity
boundary obviously requires that the boundary be established
first.

     Because the Classification Review Area  is intended to  be
a  simple  approximation of the zone where  ground  water may
most  likely  be affected by  a  facility/activity,   precise
location of this boundary is not necessary*   In general, the
facility/activity boundary should  encompass  all potentially
polluting activities  related to the Federal action  for which
the classification decision is  needed.

     In some  cases,  it may be appropriate  to use the legal
boundaries of the facility/activity.   Because classification
will be in  response  to a Federal  (e.g.,  regulatory)  action,
the definition of facility/activity boundary  for the  purpose
of drawing  the  Classification Review  Area  limits  should  be
consistent  with   regulatory  definitions  of  the
facility/activity,  where applicable.

     Figures 3-3 through  3-6 are provided as  generic  aids  to
assist  in delineating  the  Classification  Review  Area  for
large multiple-activities or unusually-shaped facilities for
which the classifier deems  that  a simple circle  from the
center of the activity/facility is  inappropriate.
                            3-19

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                    FIGURE 3-3.  IARGE FACILITY
 Approach 1:'  Draw circle encoapassing entire facility.  Draw
              radius  froa center of circle.
Approach  1:   Draw radius froa facility boundary (solid line).

Approach  2:   Draw circle encompassing entire facility.  Draw
              radius froa boundary of circle (dashed line).
                                             I MILE
                                             2 MILES
                               3-20

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          FIGURE 3-4.  tfABCE. MULTIPLE-ACTIVITY/FACILITY
        (e.g., activities separated by more than 1/4 mile)


 Approach 1:   Draw radius from facility boundary.
Approach  2:  Draw  individual  radii from each activity.
Approach 3:  Draw circle encompassing all  activities,
             Orav radius from boundary of  circle.
                                  2 MILES
                               3-21

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          FIGURE  3-5.   SMALL. MOLTIPIJ>AeriVITY/FftfiTT|TTY
                       (e.g., under  40  acres)
 Approach 1:   Draw circle encompassing entire facility.   Draw
              radius  froa center of circle.
          FIGURE 3-6.    LONG,  IRREGULARLY SHAPED FACILITY
Approach 1:   Draw radius froa facility boundary  (solid line).

Approach 2:   Draw circle encoapassing entire facility.  Draw
              radius froa boundary of circle (dashed line).
                                             I MILE
                                             2 MILES
                               3-22

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                         CHAPTER FOUR

       CLASSIFICATION CRITERIA FOR CLASS  I  GROUND WATER
4.1       overview of the Decision Process
4.1.1     Definitions
     In EPA's classification  system,  Class I ground water is
ground water of unusually  high value.   Class I ground waters
are defined as highly vulnerable to contamination and are (1)
irreplaceable sources  of drinking water  and/or (2)  ecologi-
cally vital.  The  definitions and procedures for identifying
Class  I  ground water  are  designed   to  distinguish  these
special ground waters  from the vast majority of other ground
waters.

     Ground  water   is  considered   irreplaceable   to  a
substantial population if it would be economically infeasible
to develop  an  alternative water-supply source of comparable
quality  and quantity  in the  area,  or  if delivery  from an
already  existing  alternate source  is  precluded  by institu-
tional constraint* or transport  distance.   Ground  water is
considered  Class   I  -  Ecologically  Vital  primarily  if  it
supplies a sensitive ecological system that supports a unique
habitat.  Such ground waters will generally have an unusually
high  value  due to either  the potential  risk to  the  large
number of people dependent upon the ground water as a source
of  drinking water or the risk  of further  endangerment to
endangered  or  threatened  species  that depend  on the unique
habitat  supported  by  that ground-water  resource.   Certain
Congressionally-designated  Federal land  management  areas,
managed.for the purpose of ecological protection, may also be
considered unique habitats in some cases.

     Chapter Four provides definitions and discussions of key
words  and  concepts  important to  a  Class  Z decision  and
discusses  in detail  the  procedures  for  making  a  Class  I
determination.   This chapter  covers the possible sequence of
classification steps, corresponding data needs, and technical
methods  for each   step  in  the  decision process.   The  clas-
sification  procedure  ultimately  relies on  the professional
judgment of the classifier.   The procedures presented here

                             4-1

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may  help to simplify  and  clarify  the classification process
and  to  promote consistency between classification decisions.
Supplemental  information  about the  Class  I  classification
process  is provided in Appendices B and D.
4.1.2	General  Procedures     	


     The,  Class Z  decision process will  generally begin with
either a  determination of irreplaceability or the identifica-
tion of ecologically vital areas, followed by a determination
of ground-water vulnerability.  Preliminary data may Indicate
that one  of the  Class I criteria can be  more  easily demon-
strated  than  another.   If  so,  the  classification  process
should  begin  with  the criterion that  can  be  most  easily
demonstrated.   It is  important  to  note  that, the order  in
which  Class I  steps are performed  is not fixed.  The sim-
plest,  least  expensive,  and  most  appropriate  method  of
arriving  at the classification decision should be applied in
any  given  situation.    It  will be  up to the  classifier  to
determine  the  order  in  which  a  Class  I  procedure  is
performed.

     The  general   procedures  that  are followed in a  Class I
decision  are illustrated in  Figure  4-1.   The steps involved
in each  general procedure,  as well  as  basic data needs and
techniques  that   may  be  used  to  evaluate each step  are
discussed below.

Determine Presence of  Drinking-water Wells

     The  presence  of  drinking water wells within the Clas-
sification  Review  Area may  indicate  to the classifier the
possibility of a  Class  I -  Irreplaceable Source of Drinking
Water decision.

     Basic  data collection within the review area will most
likely include a  general survey of wells used for drinking
water.    W*ll  surveys commonly  include location, use,  and
pumpage  capacity  of existing  public water-supply wells  or
fields within the Classification Review  Area.   A  detailed
inventory of private residential wells would be valuable, but
should not  be considered necessary.   As a preliminary step,
the delineation of areas not served by public-water supplies
and the approximate number of homes  in the review area can be
evaluated.   Census data can also ba  used to  estimate the
nuabar  of  privata  veils vithin  the  Classification Ravisv
Area.  The  classifier may wish to summarize the well data to
estimate  the  number  of public  and private wells  present.
Other  general  characteristics  of   aquifers  used  in  the
Classification Review  Area  may  also  provide   information
concerning  vulnerability to contamination.

                              4-2

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                               FIGURE 4-1

           GENERAL PROCEDURE  FOR  CLASS  I DETERMINATION
                          CLASSIFICATION REVIEW  AREA
                                  DELINEATION
                            •ASIC DATA COLLECTION
 IS GROUNDWATER
IRREPLACEABLE TO
 A SUBSTANTIAL
   POPULATION
-NO—
ARE ECOLOGICALLY
VITAL AREAS
PRESENT
1
f
                           YES
IS GROUNOWATER
IRREPLACEABLE TO
A SUBSTANTIAL
POPULATION
\
i
                                           -NO-
                  ARC ECOLOGICALLY
                    VITAL AREAS
                      PRESENT
                                 YES
             IS  GROUND WATER HIGHLY  VULNERABLE TO  CONTAMINATION
                            \ <
                           YES
     GO TO
   CLASS It
  PROCEDURES
          CLAM  I
          DECISION
            SEQUENCE A
                                  i >

                                 YES
CLASS I
DECISION
  00 TO
 CLASS  II
PROCEDURES
                                                        SEQUENCE B
                                  4-3

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     Wall information nay be obtained from water authorities,
public-health  agencies,  regulatory  agencies  that permit  well
drilling, well drillers,  or other state  and local  agencies.
If wells  do not exist within the Classification Review Area,
the  classifier  will  go  to procedures  for determining  the
presence  of ecological  vital areas  within the Classification
Review Area.   A detailed discussion  of  information needs is
presented in Chapter Three.

Determine Irreolaceabilitv to a Substantial Population

     A ground-water source may be classified as irreplaceable
if it  serves a  substantial population and  if  creation of an
alternate supply source would be economically infeasible or
if  reliable  delivery  of  water  of  comparable quality  and
quantity  from  already  existing alternative sources  in  the
region  is precluded  by transport distance  or institutional
constraints.    It  is  important  to  emphasize that  the irre-
placeability criterion  is a relative test in that its goal is
to  identify  those ground  waters of  relatively high value
(compared to  others).   As a result,  these  may deserve to be
treated as  unique  or special.

     The  first step  in the evaluation of irreplaeeability to
a  substantial  population  involves  determining whether  the
user population is substantial.  In general, user populations
of 500 persons or  more may be considered substantial for the
purpose  of  these  classification Guidelines.    Ground water
serving  populations  of less than  500  persons also  may be
considered  irreplaceable in some cases, based  upon factors
discussed later in this section.

     The Agency has adopted the 500-person value as a general
substantial   population   threshold.     Population  size
considerations  are important given  that, from a risk-related
perspective, it is intended that the identification of Class
I ground water be  associated with the greater aggregate  risk
•nd potential  economic damage  faced by  larger populations.
The  500-person number  also  has  the   advantage  of  making
implementation  reasonable  as it is  the  level  at which  many
States apply well registration.

     If   the  ground   water  under  review  does   serve  a
substantial  population,   then  the  second   step  of   the
determination  of irreplaeeability  is  to make  a preliminary
determination by applying a number of screening tests. These
screening tests,  designed  to demonstrate   irreplaeeability,
include the following:
                             4-4

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     •    Uncommon pipeline distance.
     •    Institutional constraints.
     •    Comparable quality.
     e    Comparable quantity.
     •    Economic irreplaceability.


     Each  test is discussed briefly  here;  a  more detailed
discussion  is  presented in  the  next section;   The order in
which the  tests are  presented is  according  to  the  relative
cost  and effort  involved  in collecting  and  applying  each
test, with  the less  costly tests discussed first*  The tests
may be  applied in a  different order,  however,  depending on
site-specific situations.

     Screening  Test   1;    Uncommon  Pipeline  Distance.   The
concept of an uncommon pipeline distance provides a means for
estimating  the limits  of  the area within  which potential
alternative water sources  may be  located.   without  such  a
boundary, any water source in the country might be considered
a  replacement  for any  other  water  source, making the irre-
placeability concept unworkable.  If there are no replacement
sources within  a  distance  smaller than the uncommon pipeline
distance, then the preliminary  determination would  be  that
the ground water under review is irreplaceable.

     Screening  Test  2;    Institutional  Constraints.    For
purposes of the classification Guidelines, institutional con-
straints are defined  as legal or administrative restrictions
that  preclude, or  make  very  difficult,  replacement water
delivery and that may not be  alleviated through administra-
tive procedures  or  market  transactions.    Such constraints
limit access  to  alternative water  sources  and  may involve
legal,  administrative, or other controls over water use.   The
existence of  institutional constraints  can  eliminate one or
more possible  alternative  sources  from consideration (and,
likewise, indicate which alternate  supplies  are more viable
than others)   and,  therefore,  can  result  in  a preliminary
determination of  irreplaceability.

     Screening  Test  3;    Comparable  Quality.    Comparable
quality is defined in terms  of the quality of raw sources of
drinking water used  in the area,  considering  in  a general
way, both  the  types of  contaminants  that  are  present  and
their relative  concentrations.   The  intent  is  to make rough
order-of-magnitude  comparisons   to  determine  whether   the
potential alternative is  of the same  general quality as the
source and  as  other water  used for drinking  in the region,
without  conducting  a  specific,   parameter-by-pmraa«tsr
comparison.   If none  of the potential replacement sources is
comparable   in  quality   to  the  current source or  typical
sources  within the region,  then the preliminary determination
for the  current  source  would be  that it is irreplaceable.
This test is considered  a true "screening approach" since the

                             4-5

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utility  of  an  alternative  water  source based  on  quality
considerations  is more  completely  assessed  by the  economic
irreplaceability test.

     Screening  Test  4;    Comparable  Quantity.    Comparable
quantity  means  that  the  alternative  source  or  sources,
whether  surface  or ground water, is/are  capable  of  reliably
supplying  vater  in  quantities  sufficient to meet the year-
round needs of the population served by the ground water.  If
none  of  the  potential  replacement  sources can  provide a
comparable  quantity of  ground water,  then the  preliminary
determination  for the  current source  would be  that it is
irreplaceable.

     Screening  Test  5;    Economic  Irreolaeeability.    The
Agency   has   defined   economic  irreplaceability  of  an
alternative water  source principally in terms  of total water
supply costs  per household.   This does not  in  anv way imply
that the  Agency  expects that communities will  be required to
replace water  supplies  or pay for such replacements.  Again,
this is  a relative measure to  determine  the extent  to which
ground waters potentially affected by a facility/activity  are
truly special.   The economic infeasibility  test  is  designed
to  identify situations  where the  cost of replacing  a water
supply would  place an unusually high  economic  burden on  the
population  served  if the ground water  now being used became
unusable.   If  the cost  of replacing the current source would
be   economically  unreasonable,   then the.  preliminary
determination   for   that  source   would   be   that  it  is
irreplaceable.

     The third and final step  for  completing  the determina-
tion of  irreplaceability following  the application of any of
the  five  screening tests, or if the user population is  not
substantial, is  to review site-specific,  qualitative condi-
tions and make a final determination (i.e., either irreplace-
able  or  not  irreplaceable).    The  following  qualitative
factors have  been compiled  by EPA  for  consideration during
this steps   the  presence of transient populations; projected
trends  ia population  size,   economic  conditions, and water
development  projects;  and  the use  of unreliable transport
mechanism*.   These factors are discussed in more detail in
Section 4.2.3.

Determine Presence of Ecologically Vital Areas

     Ecologically  vital  areas  are  primarily  defined  as
ground-water  discharge  areas  that  serve  as  habitats   for
species  that  are  listed,   or  proposed  for  listing,  as
endangered or  threatened (pursuant  to the Endangered Species
Act as amended in 1982).  The location of proposed endangered
or threatened  species  habitats, or any Federal lands managed
for  ecological values within the  Classification Review Area
should be  identified.    The Regional  Office  of  the U.S. Fish

                              4-6

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 and   Wildlife   Service   and  the  State  Endangered  Species
 coordinator or Heritage Program administrator are two sources
 of information regarding unique habitats and/or endangered or
 threatened species.  Information about Federal lands nay also
 be  obtained from  Federal  land-management agencies,  such as
 the National Park  Service, U.S. Forest Service, and Bureau of
 Land  Management.   The  presence of Federal lands is indicated
 on  most State  and county road  maps  and on  U.S.  Geological
 Survey  quadrangle  sheets.

      For  the  ground  water  to be  considered  ecologically
 vital,  the ground  water must discharge to a unique habitat as
 defined above.   Another step in this  determination, then, is
 locating discharge areas  that may affect the unique habitat.
 Such  areas  may   include  springs,  streams,  caves,  lakes,
 wetlands,  estuaries,  coastlines,  embayments,  and  playas.
 Discharge  areas can be  located using  topographic  maps  or
 Federal and  State  Water  Resource   reports.    Section  4.3
 provides  detailed  information  on identifying  Ecologically
 Vital Areas.

 Determine Vulnerability

     The determination that a setting is highly vulnerable to
 contamination  is  based  on  a  best  professional  judgment
 approach.    When  attempting  to evaluate  vulnerability,  a
 classifier should  select the most appropriate vulnerability
 assessment tools for a given situation.  The selection should
 be  based   on  factors  such   as regional   hydrogeologic
 conditions, availability of data, and  professional experience
 of the  classifier  or support staff.    It  is  recommended that
 the classifier examine  multiple  lines of evidence to support
 a  vulnerability  determination.    Such  an  approach  might
 include an  evaluation  of  hydrogeologic factors relevant  to
vulnerability,  matching the  subject hydrogeologic  setting to
 a  highly   vulnerable   descriptive/qualitative  setting  as
provided in this  guidance,  and/or   employing one or  more
technical evaluation aids.

     In Section 4.4.1,  guidance is  provided regarding  the
hydrogeologic  factors   to consider  for  evaluating  vulner-
ability.   Selected  vulnerability evaluation  aids are  also
presented.     Where  appropriate,  benchmarks  indicative  of
highly vulnerable hydrogeology are provided.
                             4-7

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4.2       Procedures for Determining Irreplaceable scures for
          a Substantial Population
     The  purpose   of   evaluating  the  irreplaceability  of
ground-water  supplies  for  substantial  populations  is  to
identify  those waters  of relatively  high value.   For  the
purposes  of  classification,  this  is  not  meant to  require
extremely rigorous  or costly analyses.   On the  other  hand;
these  Guidelines  are designed  to ensure that truly  special
ground  waters,  due  to  their use and  irreplaoeability,  are
identified and addressed appropriately.

     The  determination  of irreplaceability process  outlined
here involves a three-step approach that is intended  to be
straightforward and  to  rely on readily  available data.   The
purpose of  this process  is to  determine whether the  ground
water within  the  Classification Review Area is irreplaceable
to  a  substantial  population.   In  the  first  two  steps,  a
preliminary determination of  irreplaceability is made  based
on the  population size  and a  series of screening tests.  The
third   step,  in  turn,   produces  a  iinal  irreplaceability
determination that  reflects consideration of several factors
that may warrant adjustment of the initial determination.

     In brief, the first step involves estimating the size of
the  ground-water  user  population  and  determining  if  the
population should be considered substantial for the purposes
of  classification.    It  the population  is  not considered
substantial,  then  the  site  in  question may   be  given  a
preliminary  not-irreplaceable  determination  and  the
classifier  may proceed to the  third step  of   the  process
(i.e.,   a  qualitative review).   if, on the other hand,  the
population is deemed substantial, then the second step of the
determination of, irreplaceability may be applied.  The second
step  involves  applying  five  screening  tests  related  to
population  size and irreplaceability  that  are  designed to
yield a preliminary determination (i.e., either irreplaceable
or  not-irreplaceable).    These  screening  tests include an
uncommon pipeline distance test, an institutional constraints
test, a comparable  quality test,  a comparable quantity test,
and  an  economic  irreplaceability  test.    Having  made  a
preliminary  determination  in  Steps   l  or  2   (e.g.,  not
irreplaceable), based  either  on  the population  size or the
outcome of the screening tests,  the classifier may then apply
a number  of qualitative criteria  designed to .recognize site-
specific  factors  that may  warrant making a  different  final
determination  (e.g., irreplaceable).   The end result of this
third   step,   therefore,  is   the   final  determination  of
irreplaceability.    Figure 4-2 presents a flow-chart designed
to illustrate how a classifier might move through this three-

                             4-8

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                                                   FIGURE 4-2

                                      SUGGESTED  METHOD  FOR  DETERMINING
                           IRREPLACEA8ILITY  TO  SUBSTANTIAL  POPULATIONS
                                        START HERE
                                                 IS THERE A
                                                 SUBSTANTIAL
                                                 POPULATION
  REPLACEMENT
SOURCES WITHIN
      OF
PIPELINE 03STANC
  AND OUTSI
      CRA
   STITUTI
  CONSTRAINTS
PRECLUDE USE OF
  REPLACEMENT
    SOURCES
   USE OF
REPLACEMENT
 SOURCE  IS
ECONOMICALLY
 INFEAS1BLE
 REPLACEMENT
 SOURCES ARE
OF COMPARABLE
   QUANTITY
 REPLACEMENT
 SOURCES ARE
OF COMPARABI i
   QUANTITY
                   PRELIMINARY DETERMINATION
                          IRREPLACEABLE
                                         PRELIMINARY DETERMINATION
                                             NOT  IRREPLACEABLE
                  QUALITATIVE
                                                          QUALITATIVE
                                             FINAL DETERMINATION:
                                                 IRREPLACEABLE
                                             FINAL DETERMINATION:
                                               NOT IRREPLACEABLE
                                         CONSIDER  OTHER SCREENING TESTS
                                                  IF NECESSARY
           ••  A clMflMcr **) apply lht«» criteria  in • different order,  if warranted bf elle-epecillc condlllont

-------
step  method  in order  to make a  ground-water classification
decision.

     Hot* that  each of the five  screening tests is designed
to  demonstrate  that a ground-water supply is irreplaceable.
Moreover, none  of  the  tests can  be used in and of itself to
demonstrate that a ground-water  supply  is  not irreplaceable.
Therefore,   if  any  single  screening   test  demonstrates
irreplaceability  and  is - consistent  with the  appropriate
qualitative  criteria,  the  ground  water  would  then  be
considered irreplaceable and the  classifier would not need to
perform any further  analysis.  On the other hand,  if a given
screening   test  cannot  be  used   to   demonstrate
irreplaceability,  then the next test should be applied.  Only
if  none  of  the   five   screening  tests,  along  with  the
qualitative review,  demonstrates  irreplaceability should the
classifier   conclude  that  the  ground  water   is  not
irreplaceable.

     The  three  steps  for  determining  irreplaceability to a
substantial population are described in  detail below.
4.2.1     Step 1:  Determination of Substantial  Population
     The first  step of the determination of irreplaceability
involves  assessing  whether the  user  population  should be
considered  substantial.   This step  entails estimating the
actual size  of  the user population  first and then making the
substantial  size   determination  itself.    Both  .of  these
decisions  involve  judgment by  the  classifier.   A  suggested
process  for  making  this  estimation  and  determination is
presented below.

     For  the purposes of  estimating  the  size  of  the user
population,  persons   using  the  ground  water  in  question
generally: include those individuals served by the following:


     •    Public  water-supply well(s)  within  the  Clas-
          sification  Review   Area  (or   appropriate  sub-
          division) i or

     •    Private veils within the Classification Review Area
          or appropriate  subdivision for persons living in a
          densely settled area  (i.e.,  census definition based
          on  1,000  persons per  square  mile,  see Appendix
          B.I); or

     e    A combination of the above.
                             4-10

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     This definition of a user population is based largely on
 concepts  already used by the Census  Bureau.   The population
 data  necessary  to  make  these  determinations  are  widely
 accessible and sufficiently up-to-date.

     In  most instances,  making these  population determina-
 tions  should be straightforward.    If the  well(s)  in  the
 Classification Review Area or appropriate subdivision serve a
 public-water  system,  then an estimate  of the number of user
 households multiplied  by the  average number  of  persons  per
 household  (2.75  on a national basis,  although each State or
 locality  may be  somewhat  different)  should  approximate  the
 total population served; if the population is served by other
 water sources, these should be accounted for proportionately.
 water  supplied  for  industrial  and  agricultural  purposes
 should not be included.   For private well users,  it will be
 necessary both to  estimate  the  population in the Classifica-
 tion Review  Area not served  by public-water  systems and to
 calculate the population  density.   The EPA  maintains a data
 system called GEMS (Graphical Exposure Modeling System)  which
 can  be  used to  estimate  both  population  and  population
 densities for a variety of areas around a point (see Appendix
 B.2 for details).  The  degree of  uncertainty associated with
 making  these  estimates  for   a   particular  situation  may
 necessitate  greater  or  lesser  reliance on  reasonable  and
 conservative assumptions.

     Once  the  population  size   has  been   estimated,  the
 classifier  should   decide  whether  the   population   is
 substantial.   User populations of  500 persons or more may be
 considered  substantial   for  the  purpose   of  this
 classification.   Likewise, populations  less  than 500 persons
may  warrant   a  preliminary  not-irreplaceable  determination
 immediately (i.e., skipping the second step of the determina-
 tion of  irreplacaability),  with the  possibility  of shifting
 to a final  irreplaceable  determination based  on  a  review of
 site-specific conditions (i.e., the third step).   Population
 estimate*  close  to  500  persons  in  size  will require best
 professional judgment.
4.2.2     Step 2:  Screening Tests to Make Preliminary Deter-
	minations	


     The second step of the determination of irreplaceability
involves applying  five  separate screening tests in  order  to
make a  preliminary determination.   Each of the five  tests
reflects the size  of  the user population or  some measure  of
the ground water's irreplaceability or both.  The tests are
designed to  identify  ground waters that are truly  special.

                            4-11

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The test*  are  presented in  a  suggested order that attempts to
minimize  the  level of  effort  and cost associated  vith  the
determination.    Specific  situations, however,  may  indicate
applying the tests in  a different  order.

     The  five screening tests for making  preliminary  clas-
sification decisions are as follows:


     1.  Uncommon or unreasonable  pipeline distance.

     2.  Institutional constraints.

     3.  comparable quality.

     4.  Comparable quantity.

     5.  Economic irreplaceability.


The  following sections  describe  methods for  applying  these
screening  tests.    Each section also  identifies and charac-
terizes data  sources  that  are relevant to the tests.   The
data sources  are generally available  from  Federal and  State
agencies or other easily accessible sources.

Screening Test 1;   Uncommon or Unreasonable Pipeline Distance

     If there  is no indication that  a different test should
be  applied  first  (e.g.,  the  classifier  knows  that  all
potential  replacement  sources will  be  unavailable due  to
institutional   constraints),  then  the  uncommon  pipeline
distance test  will probably  be the most appropriate test to
apply  first when making a preliminary  determination.   This
test sets  a  hypothetical  outer  radial  boundary around  the
site being classified which, in  conjunction  with the  inner
boundary  set   by  the  Classification   Review  Area,   or
subdivision  thereof,   establishes the   zone  within  which
alternative  water  supplies  can   reasonably  be  considered
(i.e., tft« zone between the two boundaries).   In other words,
the  te«ftf  restricts the number  of alternative  sources that
need be considered  in the  irreplaceability determination by
excluding  those sources that  are unreasonably  far away.

     In  theory,   an  uncommon  pipeline  distance  could  be
defined  as the  typical maximum distance water is  currently
piped  from the  raw-water source  to  the distribution system
for  each  population   category  within  a  given  geographic
region..   Given  this  definition;  currant  pipeline  distances
may vary,  considerably within a .region due  to a number of
factors.    For  example, regions  with  diverse topographic,
geologic,  hydrologic,  or seismic  characteristics may have a
wide variation in pipeline distances and,  therefore, may not
have a  single  typical pipeline distance.  Moreover,  pipeline

                             4-12

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distances  nay vary greatly  in length due  to  other factors,
such  as  the availability of developed water resources  (e.g.,
lakes, reservoirs,  etc.),  institutional  constraints on water
development,  water demand,  and  economic  resources,  all of
which  may  vary  within a  region.      This variability in
pipeline  distance  is  especially  apparent when  considered
across  regions.   In  the semi-arid regions  of  the West,  for
example,  water may  be  conveyed  50 miles  or  more  from  the
source to  the distribution system.   On the other hand, water
is  typically piped  5 miles or less in the  East due to other
factors  such as greater annual rainfall,  a different set of
property  rights,  and different  levels  of  urbanization  and
population  density.    Finally,  piping  distances  can range
considerably  even among  neighboring states.

     If  sufficient data exist  in a  specific  situation to
determine an  uncommon pipeline distance for the population in
question,  then the  classifier  may choose to  use a value
derived  from that data.   In  doing  so,  the classifier should
ascertain a consistent  uncommon  pipeline distance based on a
reasonably  defined  geographic region  (e.g.,  statewide)  and
populations similar in size to the population in question.

     If, on the other hand,  sufficient  data are unavailable
or pipeline distances vary widely for populations that are in
the same region and are of similar size  to the population in
question, then  it may not  be practical  to define an uncommon
distance in this manner.  Therefore, a second approach can be
used in applying this test.  This second approach is based on
the observation that, due to economies of scale, water-supply
systems  serving  larger  populations  can  afford  to  pipe
alternative   sources  of  water   from   increasingly  farther
distances.   In other  words,  for  a given  level  of economic
burden  (i.e.,  the  maximum  affordable  cost  of  piping  a
replacement  water supply  as  a  percent of average  annual
household income), larger  populations will  have larger areas
within which they  can  consider  alternative sources  (i.e.,
longer uncommon pipeline distances).

     In the  absence of  an  exhaustive survey of pipeline dis-
tances, the threshold distances presented in these Guidelines
are based on information provided by EPA's research labora-
tories and  the  Federal Reporting Data System  (FRDS)  managed
by EPA»s Office of Drinking  Water.   More specifically, data
from EPA's Cincinnati water-quality laboratories were used to
estimate  the costs  of  transporting various  quantities of
water  over  various  distances.     Using  this  information,
information  concerning  the   water  requirements  of  various
population  sizes, and household income  data,  a relationship
between population size and uncommon distance was defined.

     There  are  two  benefits to  using this  approach  for
defining uncommon pipeline distances.    First,  this approach
allows a reasonable and consistent method for delineating the

                             4-13

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area  within  which  classifiers  aight  cr-*ider  alternative
sources.   Second,  this approach allows  .  fairly definitive
measure  of irr«.placeability t±~sd on  the  economic  burden cf
transporting water  as  it relates to population size.

     Table 4-1 can be used to assess  whether  a  preliminary
irreplaceable  determination  is appropriate.   The  pipeline
distances  can be used as  lower limits  of  uncommon pipeline
distances.   For  example,  if the user  population  is between
500  and  5,000 persons, then  pipeline  distances greater than
25  miles  could  be   considered  uncommon  or  unreasonable.
Therefore, if  there are no alternative water supplies within
25   miles  of   the  site   under  review  and  outside  the
Classification Review  Area, then the ground water in question
would   be  considered  irreplaceable   for  the  preliminary
determination.

     After  the  appropriate  pipeline  distance  has  been
established, the  final step of the preliminary determination
is  to  ascertain  whether potential  replacement water-supply
sources  are  in   fact  present  within  the  uncommon  pipeline
distance  and   beyond  the   Classification   Review  Area.
Potential  sources may  include both surface or ground water
outside  of  the  ground-water  unit under  review.    Common
examples   of  surface  water  that  can  be  considered as  a
replacement  source are  rivers, streams, natural  lakes,  and
impoundments.     Alternative  ground-water  sources  nay  be
located  in the same  aquifer,  or in another nearby aquifer,
horizontally or vertically  separated from the source aquifer.

     If  a  preliminary irreplaceable determination is made on
the  basis  of the uncommon  pipeline test and if there are no
relevant qualitative criteria  that would warrant a final not-
irreplaceable  determination  (as  described  in  Step  3),  then
the final  determination would  be irreplaceable.  Note that if
an  alternative   source  falls  within  close  range  of  the
uncommon pipeline boundary, then a best professional judgment
should be  made by  the classifier  as  to whether  the source
could  b«  considered.     Note  also  that  if   the  final
determination  is based  on this  test   (i.e.,  no  alternative
sources^ exist within an uncommon pipeline distance bound*ry),
no further analysis need be  done.   It a final irreplaceable
determination  is not  warranted -Mt this  point, however,  the
classifier should continue  to  the next screening test.


Screening  Test 2;  Institutional Constraints

     The second* screening test  to be applied when determining
the  irreplaceability  of  a ground-water  supply   is whether
institutional constraints exist which sight preclude, or make
very difficult,  the delivery of an alternative supply.  This
section defines institutional  constraints, provides a process
                             4-14

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                                TABLE 4-1*
                    GENERALLY  APPLICABLE UNCOMMON
                           PIPELINE  DISTANCES
                                              Uncommon
             Population Size           Pipeline  Distance

               500   -   5,000                25 miles
             5,000   -  10,000                35 Biles
            10,000   -  25,000                70 miles
            25,000   - 100,000               100 miles
                     > 100,000               150 miles
*Note:    In developing this uitminim pipeline distance function (i.e.,
population size versus unocnmon pipeline distance), a  1 percent economic
threshold was used consistently across all population size
order to make the distance calculations as described above.  This single
ries in
threshold level differs from the economic infeasibility screening test,
•toffiTrlfr^ below,  which uses an absolute dollar economic burden threshold
that varies based on  population size.   These two tests differ for thro
reasons.    Firstf use of a  single economic  threshold  simplifies  the
calculation of mmauuui pipeline distances.   Second, even in situations
where  replacement  water supplies  are deemed  to be  within  a cannon
pipeline  distance  using  the   1  percent  threshold,   the   economic
irreplacability test will still  be used to assess irreplaceability based
on  the size-dependent,  absolute dollar  threshold.   There  is  no need,
therefore,   to calculate  ui minium  pipeline  distances  using   variable
economic burden thresholds.
                                    4-15

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for   categorizing  institutional  constraints,  and  provides
guidance  for applying the  screening test itself.

      Institutional  constraints  involve legal, administrative,
and  other similar forms  of control over access to water.   For
purposes  of  these   Guidelines,  the  Agency  has adopted  the
following definition of  institutional constraint:

      An institutional constraint is a situation in which,  as
a  result of  a  legal or  administrative restriction,  delivery
of   replacement  water may  not  be  assured through  simple
administrative  procedures  or market transactions.

      Note that this definition applies to  situations  where
replacement,  even though not strictly precluded, is made very
difficult by institutional constraints.

      While  a detailed examination of legal and institutional
issues  is  rarely  called  for,   a preliminary 'review  should
indicate  whether  an institutional constraint is present.   The
following  discussion presents  a   breakdown  of  potential
institutional  constraints and a  general  procedure   for
determining whether  a  binding  institutional  constraint  is
present  in a particular situation.    Appendix B.3  provides a
more detailed description  of  constraints,  as well as sources
of information.

      The  Agency  has  identified  various  kinds  of  potential
constraints and determined which are probably binding,.which
may  be  binding  in  some  cases or possibly  binding,  and  which
are   unlikely  to   be  binding.     For  a  straightforward
assessment,  corcarison  of  the  constraints  affecting   a
particular  source  of water,  as presented  in Figure  4-3,
should  suffice.  In  those cases where a detailed assessment
is   warranted,  the  procedure  outlined  in  Figure  4-4  is
suggested.    The  case study presented in the  next  section,
illustrating a  somewhat  complicated institutional constraint
situation,   may  also  prove   useful  when  making  less-
straightforward assessments.

      Institutional  Constraint Case Study.  A potential source
of  replacement water (e.g.,  the Rio  Grande River) may-  be
subject  to  an  international  treaty  (e.g.,  the  1944  Treaty
between* the United  States and  Mexico on  Utilization of the
Waters  of  the  Colorado and  Tijuana Rivers  and of the Rio
Grande) limiting  the amount of water  that may be withdrawn by
users in  the  United States,  and  to an  Interstate Compact
limiting  the  amount  of  water  that  may  be  used  within a
particular  state.    In  addition, that portion  of  the  rivsr
flow assigned  to  a  particular  state  may  already  be  fully
taken up  by other  users.   Finally,  the  use  for  which the
water is  being considered  as a potential  alternative source
may  be situated  some distance  from  the river and require a
right-of-way in order to get access to the water.

                             4-16

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                          FIGURE 4-3
              POTENTIAL INSTITUTIONAL CONSTRAINTS
 Probably  Binding  Constraints

      0     Water is  subject to international treaty.

      •     Water is  subject  to interstate water apportionment
           compact of litigation among states.

      •     Water   is  subject to  Federal  or  Indian reserved
           right.

 Possibly  Binding  Constraints

      •     Water is  allocated by litigation among persons.

      •     Water is  allocated by permit.

      •     Water   is  allocated  by  local water  district  or
           another local authority.

      •   Amount of water that may be used is limited:
            By public trust doctrine.
            By instream flow protection requirements.
            By state law.
            By permit.
            By local management authority.
            By  prior   appropriation(s)   that  are  all  for
            highest beneficial use.
         -  By Federal navigational servitude.

     •   Place of use of water is limited:
         -  By state law.
            By permit.
            By local authority.

Constraints Unlikely to be Binding*

     •   Water is subject to  prior appropriation  (unless for
         highest  beneficial use).

     •   Water is subject to riparian right.

     «   Physical access to property is restricted:

         -*  By  property  rights  of other  persons  limiting
            rights-of-way for pipes, ditches, conduits, etc.
         -  By Federal  or State  statutes requiring environ-
            mental  impacts  assessment or establishing other
            procedural requirements.

*  Upon application of  simple  administrative procedures  or
   market transactions.

                            4-17

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                             FIGURE 4-4

OUTLINE OF  PROCEDURE FOR ANALYZING  POTENTIAL  INSTITUTIONAL
  CONSTRAINTS  TO THE USE OF AN ALTERNATIVE SOURCE OF WATER
                      INSTITUTIONAL COTUTIAIKTS
                        •CLATCO TO IOVHCC
OC1
or
CONSTRAINT*
                                         itt
                            ACE or
                            U*C
                         •CITKICTIC
                           ACCIIS
                         •CtTHICTfO
            H**«fT
Mwnet
AITCIUTIVC  tt

 •MJCCT TO *

      1TMMT
                                            AMIIHIVTMTIVC
                            4-18

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     In  this situation, the  treaty,  the interstate compact,
the water-allocation system,  and the property rights of other
persons,  are all potential  institutional  constraints.   Each
should be considered separately.   The treaty and the inter-
state  compact may be  impossible to avoid  or change through
simple  administrative  procedures.   A telephone  call  to the
State  office in  charge of  water  allocation  would probably
indicate  that  the  water  allocation  could  potentially  be
revised  by  a simple administrative procedure  or that market
transactions  can  be  used to change the current allocation of
water.    Similarly,  informal contact  with a  State Attorney
Generalfs office  should indicate that  the  problem of access
could potentially be resolved through purchase of an easement
or  right-of-way,  or  that   the  administrative  process  of
eminent domain could potentially be used to provide access to
the  water.    In  such  situations,  a  binding  institutional
constraint   probably  would  not  be  present,  despite  the
potential constraints that were identified.

     Once the institutional constraints for a classification
decision  have been categorized  in terms  of  their potential
for  being  binding,   the  screening  test  itself  should  be
applied.  That is, if the institutional constraints affecting
the  delivery of  alternative sources  are  considered to  be
sufficiently  binding,  then the  classifier  may conclude that
the  user population's  current  ground-water  supply is irre-
placeable for the preliminary determination.   Note that the
classifier  should  make  a   best  professional  judgment  if
several alternative sources with varying levels of  constraint
are available.   If,  upon review  of the relevant qualitative
criteria  (Step  3),  the  final determination is  also irre-
placeable,  then  no further  analysis  need be performed.   If
application  of  this screening  test in  conjunction with the
appropriate   qualitative  criteria  does  not  result  in  an
irreplaceable  determination,  however,  then  the  classifier
should apply  the next screening test.

Screening Test 3;  Comparable Quality Analysis

     One* m  potential  alternative source(s)  has been located
within  the  boundary  of  an  uncommon  pipeline  distanca  and
outside the Classification Review Area and the classifier has
determined that no institutional constraints exist that would
preclude, or  make very difficult,  delivery of water frca the
alternative source, the next  step is to determine whether the
source offers water of quality and quantity comparable to the
user population's  current ground-water supply.   This section
describes the comparable  quality  screening  test  while  the
next section describes the  comparable quantity  test.   Note
that the  comparable  quality  test  need not be applied before
the  comparable  quantity  test.     If  the   situation  and
availability  of data suggest  that the quantity test should be


                             4-19

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 applied  first (and followed by the quality test if need be) ,
 then  the tests may be applied  in that order.

      The term comparable quality  is defined  as the level of
 water quality that is not substantially poorer than other raw
 drinking-water  resources in the region.   To be considered of
 comparable  quality,  the quality  of  the  alternative  water
 resource should  be (within an order-of-magnitude)  as good as
 or better than existing  drinking-water resources, taking into
 account  the precision of the  measurement  of  each parameter.
 For example,  an existing water source  may have an average of
 93  ag/L  IDS, with a  range of  75  mg/L  to  100  mg/L.    An
 alternative water source may be considered not of comparable
 quality  if  it has an average TDS  of  930  mg/L  with a range of
 750  mg/L to  1,000 mg/L.    For some  parameters of  concern
 (e.g.,  taste,  color,  odor),  the evaluation  may be  highly
 subjective.   Again,   the  test  is meant  to  be a  relative
 evaluation  which  considers  a  few  general   categories  of
 parameters  (e.g.,  TDS,  organic  compounds,   heavy  metals,
 radionuclides,   and  other  secondary   physical/chemical
 properties).

      The  rationale for  incorporating  this test is  to  allow
 for   quick  and   inexpensive  appraisals   of the  utility  of
 alternative water sources.  More comprehensive assessments of
 irreplaceability  can  be   obtained   through  the  economic
 irreplaceability  analysis outlined in Screening Test 5.   This
 test  does include a water treatment component.

      Existing information on  water  quality should  be  used,
 given the  very  high cost  of new  series of  sampling  and
 analysis.   The   comparison  is intended  to be  relative  and
 subject  to professional judgment.   At  the  Federal  level,
three important  sources  for water-quality information may be
 consulted:   EPA,  the  Army  Corps  of Engineers,  and  the  U.S.
Geological Survey.   Each of these agencies has conducted, or
continues  to conduct,  comprehensive  surveys that  describe
water resources   in the  United States.   Although  not always
designed  specifically  to provide detailed water-quality data,
 these studies provide information sufficient  to  facilitate
 the  comparable   quality  considerations  of the  ground-water
 classification system.

      EPA  has  funded comprehensive studies  of Regional  water
 quality   to  determine  the  principal  point  and  non-point
 sources of pollution.  These studies, conducted under Section
 208  of  the  Clean  Water Act,  for  example,   give  a  broad
overview  of water quality (USEPA,   1980b).  They are generally
obtainable  through  the state  and  local  agencies  which
received  the  funding.   The  Army  Corps  of Engineers conducts
similar  regional water-resource studies  in order  to examine
water  supply and  demand  within  specified  river  and  lake
basins in the United  States.   The most  useful  data resource
 from  the U.S.  Geologic Survey will  often be  the  published

                             4-20

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 basin-vide   investigations   of  ground-  and  surface-water
 resources.    The  U.S.  Geological  Survey also  maintains the
 National  Water Data Exchange  (NAWDEX),  which  is  designed to
 assist users  in the identification, location, and acquisition
 of  information on water resources.   The National Water Well
 Association  (NWWA), Dublin,  Ohio,  maintains a library of all
 U.S.  and  state Geological  Survey information on water supply
 and  quality.    Using  automated searching  capabilities,  the
 NWWA  can  identify and  list  all  publications concerning  a
 specific  geographic area.

      On  a more  local  level,   regional  planning boards  and
 government  councils also may  have information on  potential
 drinking-water supplies  and  river, lake, and  stream quality
 in  their  regions.   State  agencies that administer environ-
 mental  protection,  land-use  planning,  agricultural,  geo-
 logical   survey,  public  health,  and  water  programs,  are
 excellent  sources  of  information.   state universities (par-
 ticularly  land-grant  universities)  may  sometimes   serve  as
 repositories  of  information concerning ground-  and surface
water supplies.

 Screening Test 4;  Comparable Quantity

     The  fourth  screening  test  that  may  be  applied  to
 determine the  irreplaceability of  a user population's ground
water supply  is  the comparable quantity test.   As noted in
 the  comparable  quality test   discussion,  the  quality  and
quantity  tests  can be applied in  either order depending on
the situation  or  availability  of data.   Regardless of.which
test  is   applied  first,  however,  the  second  test  would be
 applied  if the  first  test  does  not  demonstrate   that  the
ground-water source is  irreplaceable.   The  remainder of this
section describes how the  comparable  quantity  test should be
applied.

     The  term comparable quantity  is  defined as the level of
water  quantity that  is essentially  equal  to the quantity
 supplied  by  the  current ground-water  source.   Determining
whether   the  alternative  source,  or  sources,   can  yield
 adequate quantity requires three analytical steps:


      ,e    Determine  current  supply  needs  of
            water users.

       e    Characterize  potential  sustainable
            water yield  of the alternative  water
            supply.                     '

       e    compare alternative  water supply and
            existing water demand.
                            4-21

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       Step  1;    Determine  Current  Supply  Neefls  of  Water
Users.    If  the  ground water  to  be  classified supplies  a
public-water  system,  current supply  needs will be  known by
the  water utility.   If  the ground  water to  be  classified
serves a  substantial  population using private wells, current
water  needs  must  be  estimated using  population  figures and
assumptions concerning typical water use.  For the purpose of
this  exercise, the  Agency  recommends using  the  assumption
that the  average  household uses 100,000 gallons of water per
year and  consists  of 2.75 persons.

       St»p  2:    Characterize   Potential  Sustainable  'Water
Yield  of  Mhe  Alternative  Water Supply.   The  second step of
this screening test  is to estimate the potential sustainable
yield  of alternative   water  supplies.    The  information
necessary to  make this estimate  is  best obtained  from the
published studies  discussed  in  Chapter 6  (Insufficient Yield
Test)  of   these  Guidelines.   When making the  estimate,  the
classifier  should note  that  routine  water- shortages  in
communities  currently  served  by  an  alternative source may
indicate  that  the alternative  source  would  be theoretically
unable  to  provide  water   for  an  additional  population
increment.   Rapidly  falling ground-water levels over time
also may   indicate that an  alternative source would  not be
capable  of  consistently  providing  sufficient yield  year-
round.     Finally,  even  if  levels  are  not  falling,  the
alternative source may be unavailable for additional usage if
proper  resource  management  techniques are  maximizing  the
yield while holding the water level constant.  In cases where
the ability of an  alternative source to meet the needs of the
substantial  population  is   unclear,   a  more  quantitative
analysis may be necessary*

       Step 3;  Compare Alternative Water Supply and Existing
Water  Demand.   The final  step  of this  screening tes'-  is to
compare the  potential  yield of the  alternative water supply
with current water needs.   For  this step,  water needs may be
considered on an annual or monthly basis.  In cases where the
alternative  source  is   located  in  a  water-rich  area,  the
comparison of  user needs and source yield may  be done on an
annual  basis.    The  comparison  should  be  conducted  on  a
monthly basis,  however,  if the. alternative  source  is ground
water  under  existing  or  potential  stress  or   if  the
alternative  source  is  a  surface water  with  considerable
month-to-month  variability in  flow.    Important  sources for
water-quantity  information  include  local water  utilities,
State water agencies, and the U.S. Geological Survey.

       Once the user needs and replacement source yields have
been  derived  and  compared, the  comparable  quantity  test
itself should be applied.  That is, the  classifier should use
professional  judgment to  determine whether  the replacement
source  could  adequately  supply  the  user  population  with
sufficient quantities  of water.    If  the  replacement source

                             4-22

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 cannot  supply essentially all of the user population's water
 requirements,  then the current ground-water source should be
 considered  irreplaceable for  the  preliminary determination.
 If  this  determination is  made and  review of the  relevant
 qualitative   criteria  does  not warrant  a  different  final
 classification,   then  the  final  determination  would  be
 irreplaceable and  no further  analysis need  be  done.    If
 application   of   the  comparable   quantity  test  does  not
 demonstrate   that  the  current   ground-water   supply  is
 irreplaceable,  on the  other  hand, then the  final screening
 test can  be applied.

 Screening Test 5;  Economic Irreplaeeability

       Having  determined   the  location  of   acceptable
 replacement water sources that are institutionally available
 and of  comparable quality and  quantity, the  final screening
 test  to  be  applied  is  the economic  irreplaceability test.
 The remainder of  this section discusses the rationale behind
 the economic  irreplaceability test, methods of estimating the
 cost  of  replacement  water  supplies,  and the  application of
 the test  itself.

       The Agency has defined economic irreplaceability of an
 alternative  water source  principally in terms  of cost per
 household of  using the alternative water source.   This does
 not in anv way imply that the Agency expects that communities
 will be required  to  replace  water supplies or pay  for such
 replacements.   Rather, this relative measure  is  designed to
 determine the  extent  to  which  ground  waters  potentially
 affected  by  a facility  or  activity are truly special.   The
 economic  irreplaceability test itself is  designed to balance
 different levels  of replacement water  affordability  against
 various population sizes.  Again,  this approach  is  based on
 the concept that  larger populations potentially face greater
 aggregate health   risks  and adverse economic  impacts should
 ground-water  contamination   occur.     Further,   the  test
 recognizes that  smaller  populations  generally pay a higher
 per unit  price for water than do larger populations due to
 economies of  scale.    Therefore,  the  test  is  designed  to
 identify  ground waters that  are truly special by comparing
 economic  burden of replacement to systems of similar size.
 Based on  this  rationale, the  economic test presented  here
 gives general guidance on when the costs of replacement for a
 given population  size should  be  sufficient to  warrant  a
preliminary irreplaceable determination.

       In order to apply the economic irreplaceability test,
 the classifier will have to  estimate the total  cost of the
user population's  replacement water-supply system  (i.e., once
the affected  systsm  components, or the entire system,  h«v«
been replaced)  in terms of cost per  household.   Having made
this estimate,  the classifier  can then compare the  cost of
the replacement  system against  an economic irreplaceability

                             4-23

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 threshold  in order to  determine  whether  or not the economic
 burden   of  replacing   the  existing   supply  would   be
 unreasonable.   The  economic  irreplaceability test, therefore,
 consists  of  three steps,  including the  estimation of  the
 replacement  supply   costs,  the  determination  of   the
 appropriate   economic   irreplaceability  threshold,  and  the
 application   of  the  test  itself.    These  three steps  are
 discussed  in  more detail below.

       step  1.   Estimate  the Replacement  Water-Supply  Cost.
 The  cost  estimate  for the replacement of  a user population's
 water  supply should  reflect the annual  costs of the  total
 system  once  the   potentially  affected  components  of  the
 existing  system  have  been  replaced.    For  example,   the
 existing system may consist  of public water supply  wells,  a
 treatment  plant,   and   a  distribution   system.     Further,
 conversion to a replacement water supply,  in this case,  might
 consist of sinking new wells in an aquifer outside of  the
 Classification  Review Area.   The total annualized  cost  for
 the replacement water-supply  system, therefore, would include
 current annual  costs  for treatment  and distribution  plus  the
 annualized costs  for the  new wells and transmission of  the
 new  water  to  the  existing  system.   If  the' current user
 population consists entirely of private wells, on the  other
hand,  then  the replacement system may  consist of  a  new
 source, a new treatment plant, a new distribution system,  and
 service costs associated  with  a  water-supply utility.    The
 replacement costs in this situation, therefore, would consist
 of the  annualized  total  costs  for  creating an entirely  new
public water-supply system.

       Appendix D  provides detailed guidance  for estimating
the per household  costs of replacement water-supply systems.
Once the  classifier has  determined which components of  the
user population's existing water-supply system would require
replacement,  the  annualized  cost per household  for the  new
system should be calculated  using  the methodology presented
 in Appendix D.

       Step   2.	Calculate  the  Economic  Irreplaceabilitv
Threshold.  The second  step of the  economic irreplaceability
test  is  to  calculate  the  irreplaceability threshold for  a
 replacement  water-supply  system  comparable in  size to  the
 system . under review.    The  approach  used  for  establishing
economic irreplaceability  thresholds for  these Guideline* is
based   on  three   primary   observations.     These  primary
observations  are as follows:


       1.    Due to  a  wide range of  site-specific
            factors, the cost of water to typical
            household users  varies  significantly
            throughout the country.


                             4-24

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        2.   Due   to  the   economies  of   scale
            associated  with  delivery  of  water
            supplies,   however,   large   user
            populations  tend  to  pay less,  on  a
            per  capita  basis,   for  their  water
            than  do individuals  receiving water
            from  a small  system.   Nonetheless,
            even  for  systems of the same size,
            water costs may vary widely.

        3.   A  threshold value  that  defines  the
            maximum feasible  cost of a  replace-
            ment  water source  can  be  developed
            for  various water   system  sizes  by
            specifying  the  replacement  water-
            supply cost that exceeds  a reasonable
            economic   burden   (e.g,  observable
            extreme water  system  costs).    This
            threshold will vary  as a function of
            system size.


       Given these  observations,  the Agency determined  that,
for  a  given population size,  the per household  water-supply
cost  (i.e.,  system costs  such  as operation  and maintenance
costs,  capital costs,  and  interest payments) below which  90
percent  of the  households in  a  user  population  typically
face, can reasonably be used as  the economic irreplaceability
threshold.   In other  words,  if  a  replacement  water  supply
would  cost as  much  or more  than  the per household  cost
observed by only  10 percent of  households,  then the  current
ground-water  source   is   irreplaceable.     Therefore,  the
economic  irreplaceability  threshold  for a  replacement  water
supply  can be  calculated  as  the ninetieth percentile per
household  water-supply cost  for water-supply systems  of  a
given size (i.e.,  user population).

       Using  the  best  available data  on  community  water
supply   system  costs,   the  Agency  derived   an  equation
describing ninetieth  percentile,  per household  water-supply
costs as  a function of system   size.   Using this  equation,
classifiers   can  calculate   the   appropriate  economic
irreplaceability   threshold.     Appendix   D presents  the
derivation of  this cost  function and  the methodology  that
should -be  used  to calculate  irreplaceability   thresholds.
Figures 4-5 and  4-6 present two representations of the  cost
function used to  calculate  threshold  values; the  first figure
covers system sizes between 500  and  1,000,000 persons,  while
the second focuses on  systems  between 500 and 10,000 persons.

       Classifiers should  note  that  the full  implementation
of the  Amendments  to  the  Safe  Drinking  Water Act passed  in
1986 will undoubtedly lead to higher costs for water-supply.
In  response  to this  statute,   the  Agency  is conducting  an

                            4-25

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I
M
O\
                $1.200
                $1.100  -
                $1.000 -
                  $900 -
            I  «  $800 -
            M  11

            *  1
            H  •  $700 -\
            •  3
            5  °
            £  v.  $eoo -
            •  M

            c
            z
$500 -



$400 -



$300 -



$200 -



$10O -



  $0
                                                 riCURE  4 - s

                              Ninetieth Percentile Economic Thresholds by System Size
                               T	1	

                                    200,000
                                 	1	

                                  400,000
	1	
 600.000
	1	

 aoo.ooo
1.000.000
                                                          System Size
                                                      (User Population Served)
                Source:
             Incorporated Analytic  of Data  Collected  by  Imertan <1987)

                               Date:   1968

-------
                                                  CURE  4-6
I
10
vj
                 $860
                 $aoo -
                 $750 -
              «  $700 -

•  g

I  s.
.  «
C  *
•  1
$600 -
                  $550  -
                  $500 -
                  $450
                  $400
                              Ninetieth Percentile Economic Thresholds by System Size
                                     	1	
                                     2,000
                                        	1	
                                        4.000
                                                 	1	
                                                  6.000
                                                         System Size
                                                     (User Population Served)
	1	T
 e.ooo
10.000
                Source:   ICf  incorporated Analysts of  D•ta CoItected  by I«mer••n (1987)
                                                 0 n t e :    1 VB8

-------
 extensive  review  of   community  water-supply  system
 affordability.     once  published  and  available,   these
 conclusions  and  criteria  may lead to changes in the approach
 for  calculating  economic  irreplaceability presented here.

        Step  3.   Apply the Economic  Jrreplaceabilitv  Test.
 Having  estimated the  total cost  of the  replacement  water-
 supply  system  for  the  user  population  under  review  and
 calculated the  appropriate ninetieth percentile  threshold,
 the  classifier  should  determine  whether  the per  household
 cost  of  the  replacement  supply  would  be  economically
 unreasonable.     If  the  replacement  supply  cost   is
 significantly  higher than  the threshold,  then the  economic
 burden  of the replacement  supply would be  unreasonable  and
 the  existing water supply  should  be considered economically
 irreplaceable  for  the preliminary  determination.    If  the
 replacement  supply cost is  relatively close to the threshold,
 especially  if   it  is  less  than  the threshold,  then  the
 classifier should consider the variability  intrinsic in  the
 threshold  cost function and use best professional judgment to
 make  a  determination.   Finally,  if the replacement cost is
 significantly  less  than  the  threshold,   then the  economic
 burden  of  the  replacement  system  would not  be unreasonable,
 and the existing source should not be considered economically
 irreplaceable  for the preliminary determination.

       Following any of these preliminary determinations,  the
 classifier should consider  the relevant  qualitative  criteria
 and, if this test is the  last  of  the five  screening  tests to
be applied or  if the test demonstrates irreplaceability, make
a final determination  of  irreplaceability.   Likewise, if  the
economic  test  is not  the  last test  and  the test does  not
demonstrate  irreplaceability,  then  the  remaining  screening
tests should be applied.
4.2.3       Step  3:   Use  of Qualitative Criteria for  Final
  '     	Irreplaceability Decisions	


       The third and final step for completing the determina-
tion of.irreplaceability for any of the five screening tests,
or  if  the user population is not substantial, is to review
relevant  qualitative criteria  that  either substantiate  the
preliminary determination  or warrant  changing the determina-
tion.    Therefore,  as  discussed  throughout  this  section,
review  of  these  criteria  in  conjunction   with  a  given
screening  test can  result in  (1)  substantiation of a  pre-
liminary  irreplaceable  determination  based  on that test;  (2)
an indication that the next screening test should be  applied;.
or  (3)  if all five screening tests have  been applied or  the


                             4-28

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population  is not substantial, a  final irreplaceable or not
irreplaceable determination.

       A  list  of qualitative  criteria  compiled  by  EPA is
given  below.   Although  the  discussion for  each criterion
indicates  whether the criterion  can suggest a determination
of   irreplaceable  or  not-irreplaceable,  the  decision  of
whether  the criterion is applicable  and how much importance
the  criterion should be  given is  left to the judgment of the
classifier.

Presence of Transient Populations

       This   criterion  could  be   applied  to  recognize  the
presence of  large transient populations or transient popula-
tions  residing for relatively long  periods of time for whom
replacement  water might be  required.   one  approach  to such
situations would  be  to  weight the transient population based
on the duration of their residence.   For example,  a resident
using ground  water from within the Classification Review Area
for 3 months  out of the year would be assigned one-quarter of
the weight  given  a  permanent  resident.  If the preliminary
determination was  not  clear,  this  criteria  could  favor
changing a  preliminary  not-irreplaceable determination  to a
final irreplaceable determination.

Projected  Trends   (Population.  Economic,  and  Water Develop-
ment)

These  criteria address  situations  of  projected  growth  or
decline  in  user  population size,  economic  conditions,  or
water-development projects  or  use.   If these projections are
based on demonstrably likely events  (e.g.,  a  subdivision is
under  construction), reflect  changes  expected  in the  near
future (i.e.,  town has  issued bids for construction of a new
water-supply  well to be constructed within  2 to 3 years), and
are  significantly different  from current  conditions (e.g.,
substantially larger or smaller population to be dependent on
the supply),  then the classifier may be justified in Baking a
determination according  to  the projections.  Therefore, this
criteria could favor shifting a preliminary determination in
either an  upward  or downward  manner,  depending on  how the
relevant conditions were projected to change.

Unreliable Transport Mechanism

       This  criterion recognizes  that although a pipeline or
some other mechanism to transport an alternative water supply
(e.g., use  of a  barge  to bring  water  to  an  island)  may be
economically  feasible,   the aechanism  may  also be  subject
periodically  to  severely   inclement weather  or  some  other
risk.  If  this risk were unacceptably  high, thus  making the
ground water  in   question  less  replaceable,  then  a  final


                             4-29

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irreplaceable  determination  could  be  favored  over a  not-
irreplaceable decision.
4.3         Procedures  for  Determining  Ecologically  Vital
            Areas
       Ground  water may be  considered  ecologically vital  if
it  supplies  a  sensitive  ecological  system  located  in  a
ground-water  discharge area that supports a unique  habitat.
A unique  habitat is  defined to include habitats  for  endan-
gered  or  threatened  species  that  are listed  or  formally
proposed  for  listing pursuant to the Endangered  Species  Act
(as amended  in 1982}, as well  as certain  types  of Federally
managed and protected  lands.

       In  the above  definition  are two terms which  require
explanation.  A sensitive ecological system is.interpreted in
these  Guidelines  as  an  aquatic   or  terrestrial  ecosystem
located   in  a  ground-water   discharge   area.    A  unique
terrestrial  or  aquatic  habitat  is primarily defined as  a
habitat for a species that is listed or proposed for listing
as  endangered  or  threatened,   pursuant  to  the  Endangered
Species Act   (as amended in 1982).   In some cases,  certain
Federal land management  areas, Congressionally  designated and
managed for the purpose  of ecological protection, may also be
considered  unique   habitats  for  ground-water   protection,
regardless  of  the  presence  of  endangered  or  threatened
species per  se.   Among  those most  likely  to be  included are
the following:


       •    Portions of  National Parks.
       •    National wilderness Areas.
       •    National wildlife Refuges.
       •    National Research Natural Areas.


       A  discharge  area is  an area  of  land through which
there  is  a net  annual transfer of  water  from the saturated
zone to  a surface-water body,  the  land surface,  or  the root
zone.   The  net  discharge  is  physically manifested  by  an
increase  of hydraulic heads with depth (i.e.,  upward ground-
water  flow).    These  zones may  be associated  with  natural
areas  of  discharge,  such as seeps,  springs,  caves, w*tlands,
streams, bays, or playas.

       Ground-water  discharge  to surface-water  bodies  occurs
in many hydrogeologic settings  and is the dominant condition
in  high  rainfall   areas.    Where  poor-quality  ground-water

                             4-30

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 discharges  to  surface  water,  a  potential  to  impact  the
 quality of those surface waters exists.

       The   procedures  for   locating  the  presence  of  a
 Federally protected endangered or  threatened  species or the
 habitat of an endangered or threatened species is as follows:


       1.   Locate  the  appropriate  (by  state) U.S.  Fish and
            wildlife  Service,  Office  of Endangered Species,
            Field Office.

       2.   Submit  to the Field  Office a  letter describing
            the  area  of  interest,   including   a  nap  if
            possible, and  the nature  of the present habitat
             (e.g., cultivated field or mature woodland).  The
            letter  should  request  information  on endangered
            or threatened  species  and  their habitats located
            in the area.

       3.   The office will usually respond within 30 days.
       The U.S.  Fish  and wildlife Service  is  required under
the  Endangered  species  Act  to provide  information  about
endangered  or  threatened  species.    Section  7  of  the
Endangered  Species Act provides a consultative  process  for
considering any  action  authorized,  funded,  or carried out by
a Federal  agency that is likely to  jeopardize the continued
existence of  any endangered or  threatened  species or result
in  the destruction or  adverse  modification of  the  species
habitat.  The U.S. Fish and Wildlife Service's, field offices
are responsible  for providing  this information upon request.
A list of regional and field offices is presented in Appendix
B.

       In  addition to  the  U.S.  Fish  and wildlife Service,
individual states  also  maintain agencies that  keep track of
endangered  or  threatened   species,  particularly,  those
candidate endangered  species and rare species  not Federally
listed.   In  most cases  State-specific  information  can  be
obtained  through  the  Natural  Heritage  Program  (a list  of
program offices  is presented  in Appendix  B) or  through  the
non-game  program  within  the  various State Departments  of
Natural   Resources.     EPA  offices   such   as   the  Marine,
Estuarine, and Wetlands Programs, may also  have information
regarding important ecological habitats.

       Information about  Federal lands may  also be obtained
from Federal  land management  agencies such as  the National
Park Service,  and Bureau of Land Management.   The presence of
Federal lands is  indicated on most State and county road maps
and U.S.  Geological Survey quadrangle sheets.

                             4-31

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4.4  Procedures for Determining Highly Vulnerable Area*
       In  addition  to  being  an  irreplaceable  eource  of
drinking   water   to  a  substantial  population  and/or
ecologically vital,  Class  I  ground  water oust  also be highly
vulnerable to  contamination,  i.e.,  the ground water must be
determined  to  be highly  vulnerable in order  for a Class  I
designation  to  apply.    Highly vulnerable  ground water is
characterized by a relatively high potential for contaminants
to  enter and  be  transported within  the  ground-water flow
system.     Thus,   vulnerability  encompasses   the  leaching
potential of the soil and/or vadose zone and  the ability of
the saturated  flow system to move  contaminants  over a  large
geographic  area   (not  just  beneath  any   given  site).
Vulnerability to contamination occurs across a continuum from
very high to very  low just as leaching potential and ground-
water velocities occur  in  a  continuum  from  high to low.  For
classification purposes, only situations at the higher end of
the continuum are of concern.

       The concept of ground-water vulnerability focuses only
on  the  inherent   hydroqeological   characteristics of the
Classification Review Area.  The determination that a setting
is highly vulnerable to contamination is based  primarily on
the best professional judgment of the classifier or technical
support staff.   This approach provides the  flexibility needed
to  address  the  wide variation  in  hydrogeologic  conditions
that occur across the nation.

       When  attempting  to   evaluate  vulnerability,   a
classifier should  select the most  appropriate vulnerability
assessment tools based on  consideration of factors such as
regional hydrogeologic  conditions,  availability  of data, and
professional experience of the classifier or  support staff.
Classifiers  are  encouraged  to  examine  multiple  lines  of
evidence to support a vulnerability determination.  Such an
approach might include an evaluation of hydrogeologic factors
relevant to vulnerability, matching the subject hydrogeologic
setting  to  a  highly  vulnerable  descriptive/  qualitative
setting as provided in this guidance, and/or employing one or
more technical evaluation aids.

       In  the  following  subsections,   guidance is  provided
regarding the  hydrogeologic  factors to consider  for evalu-
ating vulnerability.  Selected  vulnerability evaluation aids
are also presented.  Where appropriate, benchmarks indicative
of highly vulnerable hydrogeology are provided.


                             4-32

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4.4.1  Factors Related to Vulnerability
       A   large  number   of  factors   may  influence  the
vulnerability  of  a  specific  setting  to  ground-water  con-
tamination.   Table 4-2 provides  a  comprehensive,  though not
exhaustive,  list of these factors.  The relative influence of
any  one  factor on the  degree  of vulnerability to contamina-
tion varies  from region to  region  and  may vary from setting
to setting within a  region.   For example, recharge rate may
be more important in  arid regions than in  humid regions.  The
factors  are  also  highly  interrelated.    A  change in  the
magnitude  of one  factor  may  result  in changes  in the mag-
nitude of  other factors.  The  factors presented are to assist
in  the  following  discussion  and  not  to  be  taken  as  a
checklist  for each classification decision.

       The classifier will  need to select a  set  of the most
appropriate  factors   for  evaluation  based  on  a knowledge of
the  regional hydrogeology and  the interrelationships between
factors.   No  single  factor will  be likely  to  distinguish
highly  vulnerable  from less  vulnerable  hydrogeologic  set-
tings.     A  combination  of   factors  should  be  evaluated.
Several of the vulnerability  evaluation aids  described in a
subsequent section incorporate subsets of  these hydrogeologic
factors.   The following discussion is intended to provide an
overview  of  each  factor  and  its  importance  to evaluating
vulnerability.   The discussion and list are  not  meant  to be
binding.   In some settings, only a few  factors will need to
be  assessed.   Rarely  will all  or  nearly all  need to  be
reviewed in  detail.
Regional Recharge

       Recharge  of precipitation  is  the principal means  by
which  a  contaminant  released at  or  near the  surface  is
leached  and transported  through  the vadose  zone to  ground
water.   Met  recharge rate  is considered by many  hydrogeo-
logists  to  be one of the most important factors  to consider
in a  vulnerability assessment.  Nst  recharge can be thought
of as the  quantity of precipitation that is  available  for
transport,  dispersion,  and  dilution  of  a pollutant  from  a
specific point/area of introduction.
                             4-33

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                     Table 4*2
             Factors Relevant to Judging
           Vulnerability to Contamination
           (Not. Listed in Specific Order)


•  Regional  Ground-Water Recharge Rate

      Natural  recharge
   -  Artificial  recharge

e  Topography

      Slope

e  Landscape Position/Land form

   -  Recharge/discharge area location
   -  Proximity to water bodies, discharge areas
      Geomorphic  position  or  land  form  (e.g.,  river
      terraces, alluvial fans)

e  Soil/Vadose-Zone Characteristics

   -  Depth to water/thickness of vadose zone
         Depth to the seasonal-high water table
         Depth to the zone of saturation
         Thickness of the unsaturation zone
   -  Soil texture/clay content
   -  Clay mineralogy
      Infiltration capacity
   -  Porosity (primary and macro/secondary)
   -  Hydraulic conductivity/permeability
   -  Attenuative capacity
         filtration
         biodegradation
         •orption
         fixation/precipitation
         volatilization
   -  Vadose-zone media
         silt/clay; shale;  limestone;  sandstone; bedded
         limestone, sandstone,  shales;  sand  and gravel
         with   silt  and   clay;  metamorphic/igneous;
         basalt; karst limestone

e  Aquifer and Ground-Water Flow System Characteristics:

   -  Hydraulic conductivity
   -  Effective porosity (primary and secondary)
   -  Hydraulic gradient (horizontal and vertical)
   -  Ground-water flow velocity

                        4-34

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Attenuativc capacity
.  path length/media contact time
.  sorption properties
.  ion-exchange capacity
.  conditions conducive to chemical demobilization
Aquifer media
.  rock  type  (shale,  sandstone,   limestone,
  metamorphic  and   igneous  rocks,   karst
  limestone)
.  mineralogy
.  grain-size distribution
.  organic carbon content
Sequence of aquifers and non-aquifers
Degree of confinement
                 4-35

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        In general, the higher the recharge rate, the greater
 the potential  for ground-water pollution where  a  source is
 present.   In areas where there is  little precipitation/ there
 is  correspondingly little  rech&rge.   For  this reason,  areas
 of  low  precipitation  will tend  to  be  considered  as less
 vulnerable to contaaination than areas of high precipitation.


        The amount of precipitation that ultimately recharges
 is  dependent  on  a   number  of  site-specific  parameters,
 including  slope  (topography)   and   soil/vadose  conditions.
 Slope  of  the  land  is an indicator  of  the proportion  of
 precipitation that  runs off.   Steeper slopes  usually mean
 more runoff and  less  recharge.   Soils that develop on steep
 slopes  are  generally thinner and  less mature  (i.e.,  lower
 subsoil  clay content)  than those  that develop on less steep
 slopes.   The  attenuation  capacity of  the  steep  slope soils
 is, as  a  result,  lower.   Areas with  low-permeability soils
 (e.g.,  clayey  textured soils with  low macro-porosity) also
 tend to have  lower recharge rates and higher runoff rates.

       Recharge rates  and,  thus, the  potential for pollution,
 can  be  augmented by  artificial   recharge  and  irrigation.
Artificial  recharge is  defined  as any process by  which man
 fosters  the transfer of surface water into the ground-water
 system  (Freeze and Cherry, 1979).   In  some areas, artificial
 recharge  and irrigation are considerable  and should, there-
 fore,  be factored into  the  vulnerability evaluation.

Topooraohv

       Topography (or  slope)  influences the likelihood that a
pollutant  will  run off or recharge  the  ground  water.   In
general, the  flatter the slope,  the more likely recharge will
occur and  contaminants will  infiltrate to  the ground water.
A steeper  slope implies a  greater  proportion of runoff than
recharge   and,   therefore,  less  contaminant  infiltration.
Slopes  greater  than  18 percent  have  the greatest runoff
capacity  (Aller et al.,  1985).

       Soil/vadose zone conditions also influence the propor-
tion of  runoff and  recharge (see  below).    Sandy textured
 soils generally  allow  for more recharge  than clayey  soils.
For  this   reason,  both  topography   and  soil/vadose  zone
conditions  must  be considered  together.   Note that in the
alluvial basins in southwestern states, most recharge  occurs
 in the steep  alluvial  fans  at the base of the mountains.

       water-table gradients  may  be  related  to topography.
Areas with steep slopes are more likely to have high ground-
water flow velocities  due to the  generally steeper ground-
water gradients.   The ground-water flow velocity influences
potential  for  attenuation in aquifer media.    High ground-
water flow velocities  usually result  in lower attenuation due

                             4-36

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to  the  shorter contact time between  the  contaminant  and  the
soil and aquifer media.

       The classifier should be aware that topography may  not
be very relevant to a vulnerability evaluation if significant
artificial changes  to control runoff  (e.g.,  storm drains  or
drainage ditching) have occurred.

Landscape Position/Land Form

       The  position  of  a  potential  contamination  source
within  the  landscape or geomorphic  landform can be  used  to
screen ground-water vulnerability  because of certain associ-
ated  hydrogeologic  conditions.    For example,   recharge  and
discharge  areas   are  commonly   inferred  from  landscape
positions.    Because  recharge  is  the  primary   mechanism  by
which  contaminants   are  leached  and  transported to  ground
water,   contamination  is  more   likely   to   occur  if  a
facility/activity is located in a ground-water recharge area.
On  the  other  hand,  discharge areas  are  less vulnerable  to
contamination because  recharge is  minimal.   The  net  movement
of  water  is  to  the surface  in  these areas  and recharge  is
less  likely  to  penetrate  to an  appreciable depth,  except
under  some unusual  conditions  of  highly  induced  head  or
geochemical density effects.

       The  position of  a  facility/activity within  certain
geomorphic units or landforms can  also be used to screen  for
ground-water  vulnerability.   The topography  and  physical
characteristics  of  certain  geomorphic units/ landforms  are
sufficiently  predictable   in   some   regions to generally
determine their  hydrologic behavior.    For  example,  alluvial
fans and glacial outwash plains are commonly characterized by
coarse-grained material which generally implies  high hydrau-
lic conductivities and ground-water  flow  velocities,  both of
which tend to increase vulnerability.  Glacial  moraines,  on
the other hand, may be composed  of clayey till in some areas
and be  judged to be  less  vulnerable due to generally lower
hydraulic conductivities.

Soil/Vadose-Zone Characteristics

       Soil and vadose-zone characteristics influence ground-
water vulnerability  with  respect  to  the  amount  and  rate  of
recharge and  attenuation of  infiltering  contaminants.   The
pollution mitigating potential  of the  soil/vadose-zon«  is
dependent  on  the  grain   size   (texture)  and  physical  and
chemical  characteristics  of  the  soil/vadose   zone  media.
Attenuation  mechanisms   include  mechanical   filtration,
volatilization,  dispersion,  chemical alternations  (e.g.,
fixation   and  precipitation) ,   neutralization,  oxidation-
reduction,  ion-exchange,   and   biological   (biodegradation)
processes.


                             4-37

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        Soil/vadose-zone  media  characteristics,  including
 grain  size/texture,   shrink/swell  potential  of  the  clay,
 porosity  (primary  and  macro/secondary),  and  permeability,
 control the amount  and  rate of recharge that  occurs.   Soil
 texture includes considerations  of the  amount and  size  of
 various particle sizes (i.e.,  sand,  silt,  and clay).   A soil
 with a high clay content or lov secondary/macro-porosity,  in
 general,  allows less infiltration than a soil with high sand
 content or  high secondary/macro-porosity.  '  In general,  a
 soil/vadose  zone with a large grain size and/or large macro-
 porosity has a  high pollution potential.

        A  longer path  length  and contaminant  travel  time
 through the  soil/vadose zone allows for  the maximization  of
 attenuative  processes.   The depth-to-water/thickness  of the
 vadose  zone, in part, controls the path length and,  thus, the
 time it takes  for  a contaminant  to  reach  the aquifer.   As
 path  length   and   travel  time   increase,   the  time  the
 contaminant  is  in  contact  with  oxygen  or  the  surrounding
 media  increases. The attenuation processes of ion-exchange,
 adsorption,  oxidation/reduction, bio-degradation, filtration,
 and  Volatilization  are more likely to occur  if  the depth  to
 water is great  because contact time with surrounding media  is
 increased.

        Chemical  attenuation  processes  include  adsorption
 (e.g.,   ion-exchange   and  surface  complexation)  and
precipitation  reactions.   The  degree  of  attenuation  that
oc   rs  due to adsorption processes is primarily a function  of
mi   ralogy   (i.e.,  iron  and  manganese  oxides  and  organic
me   ar  content).  A high clay content generally increases the
at   -mation  capacity  of the soil/vadose zone because  of the
ic   exchange and complexation  reactions  that occur at highly
c!r   ged surfaces on clay particles.  The presence of iron and
m.-: ganese oxy-hydroxides enhances the adsorption of inorganic
contaminants,  particularly cationic metals,  due to  surface
bonding and  coprecipitation.   The fraction  of organic matter
within  the  soil  strongly  influences  the  attenuation  of
organic contaminants because organic molecules preferentially
partition  to   organic  substances   rather  than  inorganic
mineral* or water.  Precipitation reactions are a function of
 redox  conditions and pH.  Oxidation and reduction processes
are  controlled  by the presence of oxygen in the soil media.
Redox  -reactions  may  decrease   the  solubility  of  some
contaminants.    For  example,  heavy-metal  contaminants  are
 likely  to  precipitate in oxygen-rich environments because  of
the  formation  of insoluble  metal  oxides and hydroxides.   A
high carbonate  content tends to raise the pH of soil water,
also causing   heavy  metals  to  precipitate.    Contaminant
concentrations  are  thus reduced due to  precipitation of the
contaminant  from solution.

        Mechanical  attenuation  processes include  dispersion
and  filtration.  Dispersion of contaminants results from flow

                             4-38

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 around  particles and  across pore  spaces.   This  causes the
 contaminant  to spread or disperse  so as to gradually occupy
 an  increasing  volume.  The greater  the heterogenity, the more
 dispersion  of  contamination.   Mechanical filtration removes
 contaminants which  are larger  than pore spaces  of the host
 medium  (Aller  et al.,  1985).   Thus, fine-grained materials
 such  as  clay  and  silt,  tend   to  remove  contaminants  with
 greater efficiency than a more  coarse-grained media.

 Aquifer and Ground-Water Flow System  Characteristics

       Aquifer and  ground-water  flow system characteristics
 govern the  attenuation capacity of the ground-water environ-
 ment  and  the ability  of  this   environment  to  transport
 contaminants.   Ground-water  velocity, which is a function of
 hydraulic  conductivity,  hydraulic  gradient,   and  porosity,
 controls  the  time  available   for  attenuation processes  to
 occur.  Low permeability  and small gradient will result in a
 slow  ground-water  velocity.    Compared  to hugher velocity
 settings, the  contaminant remains in  contact with the aquifer
 medium for  longer periods of time.   This allows the attenu-
 ation  processes,  such  as adsorption and  precipitation,  to
 occur to a  much  greater extent  than if the ground water were
 moving at a faster velocity.

       Aquifer media  characteristics, such as  clay and iron
 and manganese  oxide content,  mineralogy  (e.g., carbonate con-
 tent) , and  organic carbon content,  also affect  the attenu-
 ation  capacity  of  an aquifer.    The  discussion  on  these
 attenuation  processes  as presented in the  previous section
 concerning the soil/vadose zone also  applies to the saturated
 zone.

       Aquifer porosity and  hydraulic conductivity are  con-
trolled,  in  part, by  media  type.   In granular  and clastic
rocks,  water travels primarily through primary, intergranular
pore  spaces (although  these rock types  can  have fracture
permeability as well).  In nonclastic and nongranular rocks,
water  travels  primarily  through   fractures   and  solution
openings.   A larger grain size  or  an abundance of fractures
and solution openings  within the aquifer usually indicate a
relatively high hydraulic conductivity  or transmissivity and
a relatively  low attenuation capacity and, consequently,  a
greater pollution potential.

       Mechanical attenuation  processes  include  dispersion
and  filtration.    Dispersion  of  contaminants results  from
ground-water flow velocity  variations  around  particles and
across pore spaces.   This causes the contaminant to spread or
disperse so  as to gradually occupy an  increasing  volume  of
the  flow  system  (Aller  et   al.,   1985).    The greater the
heterogenity,  the more ground-water flow variations possible,
thus,  more  dispersion  of contamination.   Mechanical filtra-
tion removes   contaminants which  are larger  than the  pore

                             4-39

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•paces of  the  host medium (Aller et al.,  1985).   Thus,  fine-
grained  materials,  such  as  clay and  silt,  tend to  remove
contaminants  with  greater efficiency  than  a more  coarse-
grained media.
4.4.2	Evaluation Aids for Assessing vulnerability	


       In   this  section,   selected   evaluation   aids   are
presented  as  tools  which  may  be  used  to  assist  in  a
vulnerability   assessment.     After  selecting   the  most
appropriate hydrogeologic  factors,  the classifier  may choose
to employ  one  or more of these quantitative evaluation aids.
The aids provide  a framework for examining the importance and
interrelationships  between  factors.    Each type  of aid  is
described  and general procedures for use in the vulnerability
evaluation are   provided.    Vulnerability  evaluation  aids
include the following:

     e  Descriptive/Qualitative Aids

        -  Historical Evidence
        -  Descriptions of General Hydrogeologic Scenarios

     e  Quantitative Evaluation Aids

        -  Multiple Factor Methods
        -  Numerical Ranking Systems
        -  Zntegrative Methods


     The choice  of which evaluation tool to use is dependent
on the  quantity  and  quality of available  data.   If limited
data are available,  then it is best to use the descriptive/-
qualitative tools.  The quantitative approaches are generally
dependent  on  detailed  information  for the  Classification
Review Area.

     Descriptive/qualitative evaluation aids nay be  used as
part of a  screening process which would help determine if-the
ground   waters   are  likely   to  be  classified  as  highly
vulnerable.   In some cases, the vulnerability of  the ground
water to contamination  may be readily apparent solely on the
basis  of  descriptive/qualitative  aids.   The  quantitative
evaluation  aids,  along with available benchmarks  indicating
relative   ;lnerability,  could be  used when vulnerability is
less appaxant  and more detailed sraa^spscific information 1*
available.
                             4-40

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 Descriptive/Qualitative Aids

      Two  descriptive/qualitative  aids nay be considered at a
 screening  level,   historical  evidence  and  vulnerability
 scenarios.    These  aids  generally  require  a  minimum  of
 information  about the  hydrogeology of the  review area.   The
 historical  evidence approach  is  meant  to  be  a  "quick-and-
 dirty"  assessment  where  information  on  water  quality  is
 available.   It  is not  meant  to be an analysis that can stand
 alone.    The vulnerability  scenarios are  intended  to  help
 identify  those  areas where vulnerability is readily apparent.


      Historical  evidence  of  a number of serious ground-water
 contamination   incidents   in the  ground-water  unit  or
 Classification  Review  Area  is generally  a  good indication
 that  an area is  highly vulnerable to  contamination.  The lack
 of  contamination does  not necessarily mean that  the area is
 not highly vulnerable,  especially  if  no  source activities
 have  been present.   On the other  hand,  a lack of significant
 contamination in areas with significant source activities may
 suggest  a lower level of vulnerability  or  initiate  a  more
 detailed  review.

      Information about  existing   water quality  is  usually
 available through State  and  local  health  departments,  the
 U.S.  Geological  Survey   Water  Resources   Division,  State
 geological surveys,  and  the  EPA.   Information about historic
 land-use  activities  can be gained from  tax assessment maps,
 zoning maps, land deeds, air photos,  facility permit applica-
 tions,  Environmental  Impact Statements, and  interviews  with
 people familiar  with the area.

      Historical  evidence is best used as one line of evidence
 indicative  of  vulnerability.   The hydrogeologic  factors as
 well  as other evaluation aids  should be examined.

      A second qualitative approach is to compare a setting to
 vulnerability  scenarios representing highly vulnerable  and
 not highly vulnerable  conditions.   The general procedure for
 implementation  is to  match  a  real,  candidate setting to  a
 conceptual vulnerability scenario.

      The  regional hydrogeologic data necessary . to implement
 this  procedure  may be  available from U.S.  Geological Survey
 reports,   State geological   surveys,   U.S.   Department  of
 Agriculture  (USDA)  Soil  Conservation Service  soil  surveys,
 scientific  books  and   journals,  county/  regional  reports,
 facility  permit  applications,  Clean Water Act  Section  208
 studies,  Environmental  Impact statements,  and  Safe  Drinking
Water Act Sole Source Aquifer  (SSA) studies.

      Scenarios  that are  more likely  to  be judged  highly
vulnerable include the following hydrogeologic settings:

                             4-41

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      •  Shallow  unconfined  sand  and  gravel  aquifers  with
         •andy soils/vadose zones.

      •  Karstic aquifer systems exhibiting conduit flow where
         this  aquifer  is exposed at  the land  surface  or is
         covered by highly permeable  surficial  deposits vith
         shallow depth to water.

      •  Shallow,  basaltic,   volcanic  rock  aquifers  with
         extensive fractures, lava tubes, weathered zones, and
         large  secondary porosity  where  such  aquifers  are
         overlain by highly permeable  soils or soils developed
         in volcanic materials.

      •  Islands  comprised  of porous,   sandy  soils with  an
         unconfined, fresh-water aquifer.

      •  Shallow coastal plain  aquifers composed primarily of
         coarse   sand   and   gravel,   over  semiconsolidated
         carbonate rocks or fine-grained  aquitards.

      •  Other areas  with thin, highly permeable unsaturated
         zones and/or  saturated zones with rapid ground-water
         velocities (e.g., fractured bedrock areas).


      Scenarios  that  are less likely  to  be  judged  highly
vulnerable include the following hydrogeologic  settings:


      •  Confined aquifers overlain  by a very thick confining
         unit  of low permeability.

      •  A  buried  valley aquifer overlain by  thick,  clayey
         deposits.

      •  Vary  low  permeability stratigraphic units  in close
         proximity to  ground  surface  (s*g.,   clay,  shales,
         unfractured crystalline or metamorphic  rocks).

      •  Oischarg* areas or  other  areas with  extremely low
       •  recharge.

Quantitative  Evaluation Systems

      Three   general   types   of  technical  evaluations  are
available: multiple-factor criteria listing,- msmnrical rating
systems, and  integrative analyses.   Multiple factor criteria
listing  evaluations  tend to require  lower  levels of sophis-
tication and  data, numerical  rating  systems require greater
levels,  and integrative analyses  require the highest levels.
Benchmarks indicative  of highly vulnerable are provided only

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 for   selected   numerical   rating  systems  and  integrative
 analyses.

     Multiple-factor Criteria Listing

     A  common  method  for  evaluating  vulnerability  is  the
 Multiple-Factor  Criteria  Listing Approach.    This  type  of
 measure   requires  the   selection  of  specific,   measurable
 hydrogeologic factors  (e.g.,  depth to water)  and a criterion
 for  each  factor against which a real, highly vulnerable type
 of setting will be compared (e.g., less than 10 feet depth to
 water).   The criterion for  each hydrogeologic  factor  will
 commonly  be selected  based  on a  knowledge  of  the  natural
 range of  that factor  in the region.   Criteria selection must
 consider  the interrelationships  between  factors, such  that
 mutually  exclusive criteria are not selected.  For example, a
 low-hydraulic conductivity  soil,  a thick vadose  zone,  and a
 high  recharge  rate,   are  usually  mutually  exclusive.
 Assessing compliance  to  the  criteria,  however,  typically
 assumes that the factors are independent.

     It is  essential  to establish decision rules for judging
 if a setting is highly vulnerable.  For example, the decision
 rules  could require  that  a  setting  be  considered  highly
 vulnerable  if any  single factor meets  the highly vulnerable
 criterion.   Alternatively,  it  may  be decided  that  it  is
 necessary for  all, or  perhaps  a  subset,  of the  factors  to
 meet the  highly vulnerable criteria  in order  to  establish a
 setting as highly vulnerable.

     The  principal problem  with the Multiple Factor Criteria
 Listing Approach is  that interrelationships between  factors
 are  typically ignored when establishing the decision  rules.
 Ignoring  the interrelationships between factors  can lead  to
 erroneous vulnerability  decisions,  as well  as  inflexibility
 in considering  unusual  circumstances or compensating  factor
values.    For instance, for a given hydrogeologic setting,  the
trade-off between a slightly  below criterion,  depth to water
 table measure and  an  above criterion, aquifer transmissivity
measure   Might  not  be  considered   in   a  multiple-factor
 criteria-listing approach.    A  more  sophisticated  aid  for
 evaluation may  be  needed   to  fully   represent  such
 relationships.    As a result, the  multiple-factor,  criteria-
 listing measure  can  be somewhat  inflexible  when  considering
 compensating hydrogeologic characteristics  if the  decision
 rules are inflexible.

     One  criteria-listing  approach  that  will  allow  more
 flexibility  is  to use  a  classification  system  composed  of
 three or more classes for each factor.  One class is reserved
 for the true highly vulnerable  conditions  that are judged to
be beyond compensation.  Another class is  established for the
 ideal  true,  not  highly  vulnerable  conditions.     The
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 intermediate   class  is   designed  for   consideration  of
 compensating factors.

      The  most troublesome aspect of multiple-factor criteria
 listing   concerns  the  selection  of  a  highly  vulnerable
 criterion for  each  factor.  Typically, the  criterion  value
 indicating a highly vulnerable setting may simply  be chosen
 from  the  infrequently occurring values  within the  natural
 range  of   factor  values.    Alternatively,   the  selected
 criterion may   be  a  surrogate  for  a  more  sophisticated
 analysis,  such  as  time  of  travel or  risk.   Zn  general,
 assigning a highly  vulnerable  cutoff value to  a  particular
 factor  is  a  matter  of  best  professional  judgment.    For
 example,  it  is  difficult to find a cut-off value for depth to
 water such that a setting with a depth to water slightly less
 than  the  cutoff will  always  be  considered  highly  vulnerable
 and a setting with a depth  to water slightly greater than the
 cut-off  value  will  always   be   considered  not  highly
 vulnerable.   The  selection of a  highly  vulnerable criterion
 for depth to water has no one correct value.

      The   multiple-factor,  criteria-listing  approach  is
 exceptionally  easy  to implement  where the factors selected
 are easy  to  measure  or estimate.  Any number  of factors  can
 be considered.  Few  single  factors  or  criteria,  though,  will
 be appropriate  at a  regional  or national  scale;  and a set of
 factors  and  criteria  developed  for  one region may not  be
 identical  to a  set of  factors developed for another region.

      It  is  recommanded  that at  least three  hydrogeologic
 factors listed  in the numerical rating system referred to as
 DRASTIC  (see the  next section) be  considered.   At the State
 level,  it  may  be  possible  to compare  highly  vulnerable
 criteria  to  the criteria for siting hazardous-waste disposal
 facilities.   An acceptable  site under such  criteria  would
 likely  be considered  not  highly vulnerable.    According  to
 Monnig  (1984),   a majority of  states have established  such
 criteria.

                Ranking Svstemfs^
     The)   numerical  rating  type  of  assessment  tool,  in
addition  to establishing factors, assigns hierarchial ranges
to each 'factor.   The range for each factor is subdivided and
assigned  a relative numerical rating indicating the relative
importance of  that  range  interval to  vulnerability.   For
example,  the factor depth to  water could be subdivided into
seven  categories,  as  shown in Table  4-3   (see  page 4-49).
Each category  would be given a rating from  1  to  10,  with 1C
being  the  most  vulnerable.   In  this way,  a vulnerability
continuum  is established.  The numerical  factor  ratings can
also  be  multiplied  by  a  weight  in  order  to  reflect the
relative  importance of the  factors.   For example, depth to
water  may be  a  factor considered twice as  important as the

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 slope of land.   Therefore,  the depth-to-water factor  rating
 would ba multiplied by .a weighting factor of 2.   Finally,  the
 factor ratings,  or weighted  factor ratings,  are added to give
 a total vulnerability score.

      A number  of numerical rating  systems have been  developed
 for various purposes.   Those  most appropriate for  assisting
 in a  vulnerability  assessment generally meet the  following
 criteria:


      •  Should not be  activity specific  (i.e., only relevant
         for one  very specific  contamination  source).

      •  Should consider only  hydrogeologic factors or  the
         hydrogeologic  section  should  be  separable  from  the
         rest of  the calculations.

      •  Should consider  only  a  ground-water, contamination
         pathway.

      •  Should be suitable  for the  setting in  which  it is
         being  applied.


      Two numerical ranking systems are presented  as  generally
consistent with this vulnerability concept:


      •   DRASTIC  (Aller et al., 1984)

      •   LeGrand  System for  Evaluating  Water-Disposal   Sites
         (LeGrand, 1980)


This  list  is   not intended  to be  exhaustive.   Other systems
may  meet  the criteria  listed  above   and may be  deemed
appropriate.

      In  preparing this list,  a number  of  numerical rating
systemmsjiwre examined,   other  systems were not listed because
they  eaioBpass other contamination pathways (direct contact,
surface^water, or air)  and/or source and contaminant charac-
teristic*  which  were   found  to  ba  inconsistent  with  the
concept  of vulnerability.     For  come  rating systems,  the
hydrogeologic  portions  could  not  be   isolated   and  used
separately  as  indicators of  vulnerability.    In  some cases,
the  rating systems  are  too  data  intensive, too  activity
specific, or employ one of the systems listed above.

     For each  numerical  ranking system  listed,  a bench mark
score  has  been  suggested that signals   if an   area may be
classified  as  vulnerable.     For   example,   in   the DRASTIC
system,  a score  of around  15C  or greater generally  indicates

                             4-45

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 that a  review area  is highly vulnerable  for high rainfall
 areas.

      The degree  of confidence in  a  numerical rating syste*
 •core is,  in  part,  a  function  of  the reliability  of the
 hydrogeologic information  uaed  to rate  each  factor and the
 experience of the rater.   In settings where the hydrogeologic
 information  is  veil  established,  due  to  localised  ground
 water and geologic studies, for example, the score will have
 a  narrow  confidence band.    As  in any procedure  involving
 professional  judgment,  a  more experienced  or better trained
 evaluator will provide a  more accurate  portrayal of ground-
 water vulnerability to  contamination.

      A numerical  rating system can be applied to the Classi-
 fication Review  Area  using one of two  approaches.   In the
 most general  approach,  the actual range  of each hydrogeologic
 factor  can  be estimated   from  available information  and  a
 single  score generated  for the entire  Classification Review
 Area.   The  average rating for  each factor  would be chosen
 where the range in the values of factor  parameters  spans two
 or more  ratings.    For  example,  if  the depth to water across
 the  Classification Review Area ranged from 5 to 30  feet, and
 this range covered  two range categories (e.g.,  the 5 to 10
 foot category and the  10  to 30 foot  category),  an average
 rating would  be chosen.  This approach does not allow for the
 differentiation  between  contrasting  hydrogeologic settings
 within the  Classification  Review Area where the vulnerability
 •core is  distinctly different.

      The  second  approach  is to  map out  the major  hydro-
 geologic  settings that  have  significantly  different  vul-
 nerabilities  within  the Classification  Review  Area.   Dif-
 ferences  in numerical rating  scores of  10  to 20 percent are
 generally considered significant,   where vulnerability units
 are  mapped  out,   an area  -weighted,  average  score  can  be
 computed.  However,  if  the activity occupies any portion of a
 highly vulnerable map unit, a judgment that the ground water
 is highly vulnerable; is  appropriate.

      As An  illustration  of the mapping approach, consider the
 proposed  activity shown in Figure 4-7.  Within the  Classifi-
 cation Review Area,  three hydrogeologic settings  have been
mapped and labeled using the  DRASTIC numerical rating system.
The  DRASTIC index for each hydrogeologic setting labeled A,
 B,  and  C  is   180,  140, and  100,  respectively.    The areal
proportion of the  review area  for each setting is 20 percent,
 45 percent,  and   35 percent,  respectively.   The weighted
average DRASTIC index is calculated as follows:
                             4-46

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                          FIGURE  4-7

              ILLUSTRATION OF DRASTIC  MAPPING
                    MAP UNIT B
                    DRASTIC *I4O
                               MAP UNIT A
                               DRASTIC'ISO
                                           MAP UNIT B
                                           DRASTIC «I4O
                                MAP UNIT C
                                DRASTIC* 100
EXPLANATION
        . •
       fCtASSIFICATION REVIEW AREA BOUNDARY
t MILCS
                               4-47

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                                         Area*
           Map     DRASTIC   Proportion   Weighted
           Unit   •  Index      of Area     Index

           A        180        0.20          36

           B        140        0.45          63

           C        100        0.35          35


                         Weighted Index   134


     * DRASTIC index multiplied by the proportion of area.
     For   this  illustration,   the  nap-unit,   area-weighted
DRASTIC index  of 134 is  less  than the recommended benchmark
highly  vulnerable criterion  of 150.    If  the  activity had
occurred  in  map unit A, the designation of highly vulnerable
would have been justified.

     Each  of  the  recommended  numerical  ranking  systems is
reviewed  in  turn.   A brief  discussion comparing the various
system follows the review.

     DRASTIC  Methodology.   DRASTIC is  a  numerical ranking
system  developed  by  the  National  Water  Well  Association
(Aller  et al.,  1985)   under  contract  to EPA.    The DRASTIC
methodology can be performed using readily available informa-
tion.  It yields  a single numerical  value referred to as the
DRASTIC index.   DRASTIC was prepared using a Delphi approach
(a consensus building  approach)  on a panel of highly experi-
enced, practicing  professional hydrogeologists familiar with
the  potential  for  ground-water  contamination  across  the
county.   It builds  on  earlier systems such as  those  of the
LeGrand System (LeGrand,  1980)  and the  Surface Impoundment
Assessment  system   (Silka  and  Sweringer,  1978).    It  is
applicable: en  a regional level  (i.e.,  several square miles)
on par.with the size of  the  Classification Review Area.  It
was designed to overcome problems  of more simplistic methods
that may  ignore relevant factors  or  the relative importance
of a factor compared to other factors.

     DRASTIC is an acronym representing  seven key hydrogeo-
iogic  factors  correlated  to  the  potential  for ground-water
contamination  listed below:
                             4-48

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      D  - fiepth to the water table

      R  - Net Berharge to ground  water

      A  - Aquifer media

      S  - £oil media

      T  - Topography  (slope of the land)

      I  - Impact of the vadose zone

      C  - Hydraulic Conductivity  of the subject
         ground-water flow system


     The  DRASTIC  methodology   consists  of  several  steps
leading toward a  single DRASTIC index number.   In the first
step, each factor is given a  rating between 1 and 10 (except
for net recharge, which is rated between  1 and 9) depending
upon  the  range of  parameter values within  a  hydrogeologic
setting.   Consider  the range  of values for  depth to water,
and  corresponding  ratings,  shown  in Table  4-3.    A setting
with a depth to water of 28 feet would be rated as a 7.
                          TABLE 4.3
            RANGES AND RATINGS FOR DEPTH TO WATER
       AS USED IN THE NUMERICAL RATING  SYSTEM DRASTIC
                     (ALLER ET AL. 1985)
                       Depth to Water
                            (feet)

               Rang*                    Rating
               0-5                      10
               5-15                      9
              15-30                      7
              30-50                      5
              50-75                      3
              75 - 100                     2
                100*                       1
                         Weight:  5
                            4-49

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      In  the second step, each factor rating is multiplied by
a  factor weight  to give a factor  index.   For instance,  the
weight for  depth  to water  is  5 and, thus, if the rating is 7,
the  factor  index  is 35 (7  times 5).  For the final step,  the
individual  factor indices  are added together to arrive at the
DRASTIC  index.

      DRASTIC  has  been designed to  account for a  number of
different  conditions, among  which  are  multiple aquifers  and
confined aquifers.   The DRASTIC methodology allows  for  the
depth-to-water  rating to  be  adjusted  for confined aquifers.
With  this  technique,  different aquifers  within   the  Clas-
sification  Review  Area could   receive  a  different  DRASTIC
index.   If the aquifers are  believed  to be highly intercon-
nected as  defined Chapter  3 then the most vulnerable aquifer
should be evaluated.

      The  focus   of  the  DRASTIC  system  in   assessing
vulnerability is  the uppermost  aquifer.  Where the uppermost
aquifer  is  found to  be vulnerable, all ground water with  a
high  degree of interconnection to the uppermost aquifer is to
be considered highly  vulnerable.   Confined aquifers with  a
low-to-intermediate interconnection  to the  uppermost aquifer
are considered less vulnerable.

      The  DRASTIC  method  also   establishes a  separate  and
different set of  factor weights for agricultural activities.
Because  the Agency has decided  to  consider vulnerability as
independent of activity, only the regular factor weights will
be applied.

     A   two-tier   DRASTIC   highly  vulnerable   benchmark   is
suggested.  The tiers are  distinguished according  to hydro-
logic regions.   In regions where  estimated annual potential
evapotranspiration  exceeds  mean  annual precipitation,  the
DRASTIC  benchmark  for  highly vulnerable is suggested  to be
120.     In   regions  where   estimated  annual   potential
evupotranspiration  does not exceed mean  annual precipitation,
the  DRASTIC benchmark for highly vulnerable is suggested to
be 150.

      LeGrand System.   The  LeGrand method (LeGrand,   1980) is a
numerical rating  system designed to evaluate the potential of
ground-water  contamination from waste-disposal sites.    The
evaluation  is divided into four stages which  are   subdivided
into  ten steps.  The first stage.-  n hydrogeologic analysis.
is developed  in the  first seven steps,  contaminant charac-
teristics are not  considered in the  first  stage.   Stages 2,
        Note  there are three versions of the LeGrand System.
        Only  the  most  recent version  is referenced here.

                             4-50

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 3,  and  4  develop descriptions,  ratings,  and grades  that
 consider  both site and contaminant characteristics.

     Because  EPA has decided  that  a classification decision
 should  be independent of activity and contaminant considera-
 tions,  only  Stage  1  of  the  Le Grand  system is  directly
 applicable  to a vulnerability  assessment.

     The  hydrogeologic  evaluation  is  based  on  four  key
 parameters:

     •  The distance on  the  ground from  a source  of con-
        tamination to the  nearest  well,  surface  stream,  or
        property boundary.

     e  The depth of  water table  below  the waste  or con-
        tamination source.

     e  The approximate  slope  of the water table  and direc-
        tion of ground-water flow.

     e  The  character of   earth  materials  through which  a
        contaminant is likely  to pass,  expressed in terms of
        permeability and sorption.


     The  first  four  steps  in  Stage  l  involve  estimating
values  for  each  of  the four  key hydrogeologic  parameters.
Steps  5  and  6  provide  for  the  addition  of letters  that
identify  special  features with respect  to the site.   In Step
7, the  site numerical description is completed by adding the
four values obtained in Steps 1 through  4, to get  a total
point value for the site.

     The  following is an example  of  a LeGrand site numerical
description.
                       18 - 1539AA WQ

                    Step               Source

                     1        Distance to nearest water
                              supply
                     2        Depth to water table
                     3        Water-table gradient
                     4        Permeability sorption
                     5        Confidence in accuracy of
                              ratings
         H,Q         6        Miscellaneous site identifiers
         18          7        Total point value, sum of Steps
                              1 to 4


     The  lower  the total point value  the  less vulnerable  a
site; however,  the  total   point  value  cannot be relied  on

                             4-51

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•olely.    A  site  nay  have  a  favorable  rating  for  three
parameters  and be  exceptionally unfavorable  for the fourth.
For  example,  at  site may be  ideal in all respects except for *
high water  table.    The  total  point  value  is,  therefore,
followed  by the  values of the individual  parameters.   This
allows  both  the  weak  and  strong  features of a site  to be
graphically  recorded (LeGrand, 1980}.

      The  total  point value has been divided into five ranges
(see Table 4-4).  These five ranges are assigned grades which
evaluate  a  site  as  to  its ground-water pollution potential.
The  total number of points possible is 32.   The higher the
point value,  the more vulnerable a site is to contamination.
A  site  with  a total point value  >20 is assigned a grade of E
or F which  indicates it is a poor  to very poor place to site
a  waste-disposal  unit.   This implies that the ground water is
highly  vulnerable to contamination.  A total point value of
around  20 can,  therefore, generally be considered indicative
of a highly vulnerable  setting for the LeGrand rating system.
                  TABLE 4-4.  (LeGrand,  1980)

               GENERALIZED SITE GRADE BASED ON
              CRITICAL HYDROGEOLOGIC PARAMETERS

                                           Total
                     Grade                 Points

           A.  Excellent                     <10
           B.  Very Good                    11-14
           C.  Good                         15-17
           D.  Fair                         18-20
           E or F. Poor to Very Poor         >20
     A classifier  attempting  to stay within a narrow defini-
tion of  vulnerability will most likely  ignore Step 1 of the
analysis^ (i.e., Measuring the distance from the contamination
source   to  the   nearest  water   supply  or  boundary)  as
consideration of well distance blends a use measure into what
is  intended  to  be  essentially a hydrogeologically  based
determination.  If Step l is ignored, the total maximum point
value is  23  points.   In this case,  a  benchmark of 15 may be
generally considered to be indicative of a highly vulnerable
setting.

     For  a more detailed discussion of the LeGrand methodol-
ogy, including  parameter ranking values and examples, see "A
Standardized  System  for  Evaluating  Waste  Disposal  Sites"
(LeGrand, 1980).

                             4-52

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      Intearative Methodology

      Integrative methodologies are often considered the most
 sophisticated  evaluation aids because they can represent the
 interaction  and relative importance of the various hydrogeo-
 logic factors.  The most common type of integrative method is
 a flow calculation based on  the hydraulics  of  the ground-
 water flow system.   There  are  two calculations available-
 velocity  and time  of travel.   The tiae-of-travel measure is
 used  to  establish  an acceptable  time of travel  within the
 ground-water  flow  system; the velocity must  be  known and a
 specified point, or a specified distance, must be given.

      Flow calculations  can  be made  for aqueous transport
 (i.e.,  movement of water  molecules  only)  or  for specific
 constituents  where  a  reliable  retardation  factor  can  be
 determined.     Because   vulnerability  is  not  constituent-
 specific  by  definition,  only  the  aqueous  transport flow
 calculations should be considered.

      The  principal  advantage of a  flow calculation measure is
 that  it provides a more  direct  measurement  of hydrogeologic
 system behavior.   This  type of measure uses factors directly
 related to ground-water  flow,  according to their theoretical
 relationship.   For aqueous  transport,  travel  velocity and
 travel time are calculated as  follows:

                                 distance
                time of travel - 	
                     velocity -


     where:

             K • hydraulic conductivity

             Z - hydraulic gradient, and

               • effective porosity.
The velocity measure can be reliably derived using analytical
data generated from  hydrogeologic investigations and time of
travel.

     The difficulties  of this type of  measure are in selec-
ting  a defensible  travel  distance  or  exposure point  and
selecting the  time  of travel  criterion.    Both these values
will  be  somewhat  arbitrary  and  difficult  to justify  on
technical merit alone.   Flow calculation measures,  in order

                             4-53

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to be accurate,  also  raguire considerable data for th« entire
Clarification Ravi aw Araa and, therefore, can laad to rathar
high coats  for a vulnerability assessment.

     The  Office  of   Solid  Waste has  instituted a  time-of-
travel  (TOT)  criterion as part of RCRA vulnerability assess-
ments.     Vulnerable  settings   in  the  area  immediately
contiguous  to the facility are defined to have a TOT of less
than  100  years  to travel 100 feet.   In  addition/ the high-
level radioactive vast*  (HLW) program within the Department
of Energy has also established  a time-to-exposure criterion
as  a site-evaluation criterion.    Ten  thousand years  from
point of  release to  a potential exposure is  the HLW travel
time criterion.

     Due  to the  high  cost and data needs for performing flow
calculations,  it is  not  expected that such evaluation aids
will be used  routinely.   The two programs mentioned above use
such  approaches a*  well  as  stringent  threshold  values,
because  of  the  high  risk to  human  health  from unexpected
contaminant releases  from such facilities.
                             4-54

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                         CHAPTER FIVE

      CLASSIFICATION CRITERIA FOR CLASS II GROUND WATER
 5.1       Overview of the Decision Process
     A Class  II  designation  is provided  for all ground  water
that  is  currently  or  may be  used as a  source  of  drinking
water  regardless  of  its  degree  of vulnerability.    The
majority  of  ground  water classification  decisions  are
expected to  fall within  Class  II.   Class  II ground waters
generally  receive  the  very high level   of  protection  that
represents the "baseline" of EPA  programs designed to ensure
ground-water quality for present and future generations.

     All non-Class  I ground  water that is currently used  or
is  potentially  available as a source of drinking water  is
included  in  Class  II,  whether  or  not   it  is particularly
vulnerable to contamination.  This class  is divided  into two
subclasses; current sources of drinking water  (Subclass  IIA),
and potential sources  of drinking water  (Subclass IIB).   It
is assumed that  any ground water  which is currently  used for
drinking water  will fall in  Subclass  IIA,   unless  Class  I
criteria  apply.     A  detailed  discussion  of  the  decision
process  for  the  identification  of Class I ground water  is
presented   in  Chapter  Four.     other   ground  waters  are
considered potentially usable as  a source of  drinking water,
both  from  quality  and   yield  standpoints  (Subclass   IIB),
unless a lower resource value is demonstrated.

     The relatively shorter  length of this section  reflects
the  complementary   interrelationship   between  the
classification criteria  for  Class II and those  for Class  I
and III Aground water.    The other relevant  sections of the
document should be consulted as indicated.
5.1.1     subclass IIA;  Current Source of Drinking Water.


     Ground water is  considered  a  current source  of drinking
water  under  two conditions.    The  first and  most  common
condition is  the presence  of  one or more operating drinking-

                             5-1

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 water veils  (or springs)  within the  Classification  Review
 Area.  The second condition occurs in the absence of wells or
 springs,   and  includes  ground-water discharge  to a  water-
 supply reservoir (see Figure 5-1).

      The  concept of a  current  source of  drinking water is
 rather broad by  intent.   only a portion of the ground water
 in  the Classification Review Area must supply drinking water
 to  wells  or springs  or to  water-supply reservoirs.  It should
 also  be noted that a current source of drinking water, which
 meets the irreplaceable/highly vulnerable criteria,  is Class
 I.

      Ground waters that discharge to a water-supply reservoir
 or   portion  of  the  reservoir  watershed  within   the
 Classification Review Area are also classified as Class IIA,
 a current source of  drinking water,  if the  reservoir has been
 designated by State or  local  government  for water-quality
 protection.   Water-quality protection can be shown  by  the
 following:


      a.   Specific measures providing more  stringent  protec-
          tion within the  watershed  than  in adjoining areas.
          The protective measures may include the following:


          e  Sediment-control  regulations  that may consist of
            limiting the impervious  surface area and encour-
            aging the use  of  infiltration and wet ponds.

          e  Lot-size restrictions.

          e  Regulations for best-management practices.

          e  Limiting waste disposal  and working  with waste-
            treatment plants to try  and  upgrade  discharge
            standards.

          •  Restrictions  on  land-use  activities within  the
            watershed (e.g.,  mining, logging, certain recrea-
            tional practices).


     b.   Legislation or a  memorandum of understanding with a
       •   general  policy   statement   that  indicates  that
          watershed lands are to be  protected so that reser-
          voir water  quality will be maintained or protected.
A protected  watershed could also  include lands purchased by
the  water-supply  utility  and  managed  to  preserve  water
quality and yield.

                             5-2

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                      FIGURE 5-1

EXAMPLE  CLASS II  -  CURRENT SOURCE OF DRINKING WATER
       *
/
    I
    i
     *
       \
            DRINKING WATER
                WELL
         \
                        UNPROTECTED
                        WATERSHED
                     FACILITY
                      PROTECTED
                      WATERSHED
                  DRINKING WATER
                  SUPPLY RESERVOIR
                         5-3

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      There also  may be  circumstances  where  a  water-supply
 intake on  a  stream  or  other surface-water body  is  located
 within or  adjoining the Classification Review  Area.    The
 classifier may have  evidence to indicate  that  such  surface
 waters receive  significant discharge of ground water from the
 Classification  Review Area and these surface waters might be
 reasonably expected  to  be contaminated if  the  ground  water
 were  impacted.    In  such cases, best  professional  judgment
 should  be  exercised  to  ascertain  whether  a  Class  IIA
 designation is  warranted.
5.1.2	Subclass IIB:   Potential Source of drinking water


     A potential source of drinXing water in the Classifica-
tion   Review Area  is  one  that  is  capable  of yielding  a
quantity of drinking water to a well or spring sufficient for
the minimum needs of an average  family.   It is assumed that
all ground-water units are capable of supplying a yield suf-
ficient to  meet the minimum  needs  of  an  average  family,
unless an insufficient  yield can  be demonstrated as part of a
Class  III determination  (see  Chapter 6 for  a discussion of
the insufficient yield concept).  Water  is considered to be
suitable for drinking if it has  total-dissolved-solids (TDS)
concentration of less than 10,000 mg/L and either can be used
without first  being treated  or can  be  rendered  drinkable
after  being  treated  by  methods reasonably  employed in  a
public water-supply  system.   All  around  water should  be
presumed to meet this  standard  for  drinking  water,  unless
demonstrated otherwise  according  to a Class III demonstration
described  in Chapter Six.

     An uppermost limit  of 10,000 mg/L  TDS was chosen  for
several reasons.  Many State and Federal programs  currently
use 10,000 mg/L TDS to distinguish  potable from nonpotable
water.    Some States  set  lover  limits because  the  TDS  of
drinking water  is usually  wall below  10,000 mg/L.   A survey
of rural water  supplies (EPA,  I984a), for which ground water
was the1 principal source,  found a maximum TDS level of 5,949
mg/L.   lighty-five percent of rural water-supply systems used
sources 'of  water that contained less than  500 mg/L  TDS.
Given   th* rang*  of  TDS   values,  10,000  mg/L provide  the
flexibility needed   in   a  nationwide  program.     This
concentration  also  ensures that other  beneficial uses  of
ground water will be encompassed  in Class II determinations.
                              5-4

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 5.2      Classification  Procedures
     Assigning  a  Class   II  designation  is,  perhaps,  the
 simplest of all the classification procedures.  It is assumed
 that all  ground waters currently used  for drinking water or
 other  beneficial  uses will  fall into  Subclass  IIA unless
 Class  I criteria  apply.   All  other ground  waters  are con-
 sidered potentially usable as a source of drinking water (or
 water  for other  beneficial uses),  both  from a 'quality and
 yield standpoint, and  are  thus Subclass IIB, unless Class ill
 criteria are demonstrated.

     The   general  Class   II  classification  procedure  is
 outlined in  Figure 5-2.   If  wells and/or springs used  as  a
 source  of  drinking   water  are  present,  or  ground-water
 discharge to a water-supply reservoir occurs, then the ground
 water is  considered  Subclass IIA.   All other  ground waters
 would  be  considered   Subclass   IIB,   unless  a  Class  III
 demonstration is made.

     Specific classification  procedures and data needs for
water-quality  testing  and   water-yield   testing  were  not
 established as  part  of the Class II criteria.   The general
 rule is to presume, in the absence of  data,  that the quality
and yield  of  a ground-water  resource  is  sufficient  to  meet
the criteria for a potential source of drinking water.  Where
the ground water  can  be demonstrated to fail  the quality or
yield criteria, the result could be  a  Class III designation.
The  classifier  is referred  to  Chapter  6  for  a  detailed
discussion of  the decision processes  for Class  III ground-
water identification.
                             5-5

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                                                    FIGURE 5-2

                                     FLOW CHART FOR CLASS II  PROCEDURES
  CLASS  I
 PROCEDURES
CHAPTER FOUR
—MO
   IS A
PROTECTED
WATERSHED
PRESENT
                                                                                  YES*
 CLASS  III
PROCEDURES
CHAPTER SIX
ui
 I
                             YES
                                          YES
                                                                                  NO
                                                                              CLASS II  B
                                                                           POTENTIAL SOURCE
                                                                              OF DRINKING
                                                                                WATER
                                        * OR MATER-SUPPLY INTAKE UNDER CERTAIN CIRCUMSTANCES
                                      ** ASSUME CLASS III CRITERIA ARE

                                      NOT MET UNLESS DEMONSTRATED  OTHERWISE.

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                           CHAPTER SIX

      CLASSIFICATION CRITERIA FOR CLASS  III GROUND WATER
 6.1       overview of the Decision Process
6.1.1     Definition of Class III
     Class III ground waters are those that are not potential
sources  of  drinking water  because of  one or  more of  the
following reasons:

     1.  Salinity  (i.e., greater than or equal to 10,000 mg/L
         TDS.

     2.  Contamination,  either by  natural  processes or  by
         broad-scale human activity (unrelated to a specific
         pollution incident), that cannot be cleaned up using
         treatment  methods  reasonably  employed  in  public
         water-supply systems.

     3.  Insufficient yield  at any depth to provide for the
         minimum needs of an average-size household.
     Subclasses are differentiated primarily  on the basis of
degree  of  interconnection  to  adjacent  ground  waters  and
surface water*.
6.1.2    Background of Class III   	:	.


     In EPA's  ground-water classification system,  class III
is reserved  for  ground water that has virtually no potential
as a sourcs  of drinking  water.   Because of  the  very low
likelihood that  Class  III  ground water would  be  used  as a
drinking-water source  and  thus  pose  a risk to humans, it may
be   appropriate  in   some   situations  to  manage  existing
contamination  differently  or  take  different  preventative
measures than would be taken for Class I and II ground waters
                             6-1

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where there is a greater possibility that contamination could
result in human exposure.

     Several  of  the following key  technical  points relative
to the Classification procedures support this policy:


     e   All  ground water  is presumed to be a  current  or
         potential  source of  drinking water (Class I or II),
         unless  a  successful  demonstration is  made that the
         ground water meets the criteria for Class III.

     •   A  contamination plume  is  not, per  se,  evidence  of
         widespread  contamination;  the term  untreatable  is
         intended to describe general ground-water quality in
         the  Classification Review Area.

     •   Ground  water  will  not be  considered Class III when
         contamination  is  due to  an action  or in-action  on
         the  part of the facility in question.
6.1.3    General Procedures	


     The first step in the  Class  IZI procedure is to decide
whether  to pursue a  Class  III  determination based  on the
insufficient  yield criteria  or the  water-quality criteria.
Preliminary data  may  indicate that evidence of one determin-
ing  criteria  will be less  difficult  to demonstrate  than
another.  It is important to note, however, that the order in
which   Class  III  steps  are   performed  is  left  to  the
classifier.

     Figure  6-1   illustrates  the  general  steps  that  are
followed in  the Class III procedure.  In most cases,  it is
probably easiest  to address  the yield criteria first, unless
data  indicate otherwise.    A demonstration  of insufficient
yield automatically results in a Class IIIA designation.

     The sufficient yield criterion is discussed in detail in
Section 0.2 of this chapter.  In general, a ground-water unit
is considered  capable of producing a sufficient yield if it
can  protfttee> enough water to  meet the  minimum needs  of an
averagej-ttise  family.   If  the  ground-water  regime  is not
capable  of  meeting  the  minimum  needs  of  an average-size
family,  it  is automatically Class IZZA:   Insufficient Yield
unless .Class I or  Class II criteria have  been demonstrated.

     Ground-water  quality and treatability  in the Classifi-
cation Review Area or unit  of interest  can  also  be used as
criteria for  a Class  III  designation.  Ground  water that has
a IDS  concentration of greater than or equal to 10,000 parts

                              6-2

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                                                         FIGURE 6-t

                                              STEPS IN THE CLASS 111 PROCEDURE
                          ESTABLISH CLASSIFICATION REVIEW AREA AND COLLECT BASIC INFORMATION
O»
I
            DOES THE CLASSIFICATION
            REVIEW AREA INTERCEPT
            AN ECOLOM6ALiV VITAL ,
            AREA OR CONTAIN WELL(S)
            OR PROTECTCO WATERSHEDS 7
             IS THERE AN AQUIFER
             IN THE CLASSIFICATION
             REVIEW AREA THAT HAS
             SUFFICIENT YIELD f
             IS THE WATE* QUALITY
             EITHER GREATER THAN OR
             EQUAL TO 10,000 MO/L
             OR UNTREATA8l£
              IS THE INTERCONNECTION
              TO ADJACENT GROUND OR
              SURFACE WATERS LOW ?
  ECOLOGICALLY
  VITAL.  WELLS
  OR PROTECTED
   WATERSHEDS
   SUFFICIENT
      YIELD
210,000 MG/L TDS
   UNTREATABLE
       LOW
 INTERCONNECTION
                                                    CLASS 11 IB
                                               LOW  INTERCONNECTION
YES
PROCEED TO CLASS I OR

  CLASS n PROCEDURES
                          NO
                    CLASS IIIA
                INSUFFICIENT YIELD
                           NO
                      CLASS  II
                 POTENTIAL  SOURCE
                 OF DRINKING WATER
                           NO
                     CLASS IIIA
                HIGH INTERCONNECTION

-------
 per million (ppm)  is Class III unless criteria for Class x or
 Class II are met.   Ground water that has  less than 10,000 ppm
 TDS, but  can be  shown to  be untreatable according  to the
 definition  in these  Guidelines,  is  also Class  III.   The
 subclass  designation  A  or B  is  assigned on  the  basis  of
 degree of interconnection to  adjacent ground-water units and
 surface-water.

      Two  treatability   tests  are  presented  in   these
 Guidelines.    The . first  is  referred to  as the  reference
 technology test and is used as a screening step to identify
 various kinds of treatment methods needed to attain relevant
 health  standards.    If  none  of the treatment  technologies
 currently employed  to treat  drinking water  can adequately
 treat the ground water under review, then that ground water
 is   initially  considered  technically  untreatable,  to  be
 confirmed or denied by further economic analysis.  If one or
 more currently available  treatment technologies could be used
 to  treat the water to  the relevant quality standard, however,
 then the water is initially  considered technically treatable
 (i.e.,  Class II).   In  this situation,  the second treatability
 test,  referred to as  the  economic untreatability test, could
 be  applied  if further analysis is  warranted.   The economic
 untreatability test   is  designed to determine  whether the
 costs  of  treating  the   ground  water  would be  reasonably
 expensive  for a hypothetical  user population.   If the costs
 are  deemed   unreasonable,  then the ground  water  may  be
 considered Class III, untreatable.   If the costs fall below
 the threshold,  on  the  other  hand,  then  the  ground water
 should be  considered a potential drinking-water supply  (i.e.,
 Class II) .  Treatability  and water  quality are discussed in
 greater detail in  Section 6.3.

      Subclassification of Class III  is based on the degree of
 interconnection  of  ground-water units.    For  a  Class IIIB
 determination, a   low degree  of   interconnection  must  be
 demonstrated;  otherwise,  the ground-water unit is designated
 as  Class IIIA.  A detailed discussion of the interconnection
 criteria has been  provided in Chapter Three.
6.2    Class  III  Designation Based  on  Insufficient Yield
     One  of the three  criteria  that  can be used to define a
ground-water  unit as Class III  is insufficient yield.  Yield
is defined as the quantity of water that can be extracted or
produced  from the ground-water regime.   In  order for yield to
be considered insufficient,  it must be  practically infeasible
to produce a  sufficient supply of ground  water to meet the
minimum  needs of  an average-size household.   Agricultural,

                              6-4

-------
 industrial,   or municipal  uses  of  these marginal,  water-
 bearing areas would require significantly higher yields than
 a domestic well.  The insufficient yield criterion is based,
 therefore,  on a conservatively low yield,  below which it is
 generally considered unlikely or impractical to support basic
 household needs.  The insufficient yield concept is that all
 ground-water units  within  the  Classification  Review  Area
 (regardless   of the potential  for  subdivision),  must  be
 evaluated,   if  one such ground-water unit  is found to provide
 sufficient  yield,   then  a  Class  III  A-Insufficient  Yield
 designation  should not apply.

      A determination of  insufficient  yield will  be made on a
 case-by-case basis  at  the  discretion  of  the  classifier
 considering  the factors listed below:


      •   Water  needs of an average family.
      •   Sustainability of yield.
      e   Number of wells per household.
      e   Minimum pumping rates.
      e   Use of storage.


      The  minimum  water  needs  of  an  average  person  are
 estimated to  be  approximately  50  to  70  gallons-per-day
 (USEPA, 1975).   However,  most  values  reported in the litera-
 ture  are  greater than  50  gallons-per-person-per-day,  which
 can   likely  be  attributed  to non-essential  uses  such  as
 irrigation of lawns  and gardens.  Hater  needs also vary for
 different  regions  of  the  country.    Determination of  this
value  is,  therefore, left to the  judgment of  the classifier
whose  decision will  be based on available data and considera-
tion  of other factors.

     One  factor that must  be considered is that  water is not
used  at a constant  rate  throughout the day; there  are peak
periods when demand is high and low periods when  demand is
not as great.  A low-yielding well may be capable  if it is
possible  to  create  adequate storage  during low-use periods
 for use during high-use periods.

      Barring   more   detailed   information,   a  value  of
approximately ISO  gallons-per-day  (gpd)  per household  is a
generally acceptable yield threshold.   This value is based on
EPA's   water-supply  guidelines   that  indicate   per  capita
residential water minimum needs range from 50 to 75 gpd  (EPA,
 1975)  for  a  single-family residence.   Waste  flows  from
single-family dwellings  using  septic systems average  45 gpd
per capita (EPA, 1980, page  51).   Based on an average family
size  of 2.75 persona, therefore,  and  a  per capita water need
of  approximately  50 gpd,   a  value  of  about  150  gpd  was
obtained.
                             6-5

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      Classifiers should  not* that  a per  capita  water need
 value of approximately 100 gpd  (or  100,000 per household per
 year)  is used for the Class  I economic  irreplaceability test
 and the Class III economic untreatability  test (see Appendix
 D) .  The  Agency believes that  this  higher 100  gpd value is
 more appropriate for sizing  hypothetical public-water supply
 systems because  such systems   usually  meet needs  over and
 above basic household consumption  requirements.

      A  sufficient yield threshold should be sustainable over
 time without  temporary  (e.g.,  seasonal)  depletion  of the
 resource.   The yield can  be obtained from any number and type
 of  household wells,  including  drilled  wells, dug wells,  or
 any other  type of well available.

      Readily available hydrogeologic information exists that
 may assist a classifier in determining if a ground-water unit
 (or units)  has  a lithology  capable of meeting  the minimum
 yield  requirements.    This  information  can be  obtained from
 U.S.  Geological  and State  Geological Survey  water resource
 publications.  Logs  and specific yield tests may be available
 for wells  drilled in the  area.   Additional  information can be
 obtained from university  research  publications and scientific
 journals.   However,  in  some  cases,  the classifier may need
 more site-specific   aquifer   test  data   to  determine  the
 hydraulic  properties of a particular ground-water unit.  It
 is  important to  note  that  if an active water-supply well is
 present and in  use,  the ground-water unit is  considered to
 have a  sufficient yield and should be designated Class II.
6.3      Class  III Designation Based on Ground Water Quality
         and Treatability
6.3.1  Areal Extent of  Contamination	


     A Class  III designation can be assigned to those ground
waters that are naturally  saline,  or otherwise contaminated
beyond  levels that  would permit  their use  for drinking or
most  other beneficial  purposes.   In  order to be Class  III,
the  ground waters  oust  be  so  contaminated  by naturally
occurring  conditions,  or by the  effect of broad-scale human
activity  (that  is  unrelated to  a specific activity),   that
they cannot be cleaned up using treatment  methods reasonably
employed in public water-supply systems.

     The determination that ground-water contamination  is a
result  of broad-scale  human  activity   is  left   to   best
professional judgment.   The following lines of evidence  are

                             6-6

-------
 suggested  for  assessing if  ground-water contamination from
 broad-scale human activity is present:


      e History of multiple contamination incidents.
      e Nature and extent of contamination.
      e Adequacy of water^quality data base.


      An area that has been affected by  a number of industrial
 and other potentially polluting activities over a long period
 of time  in some  cases  may meet the concept of broad-scale
 human activity.   Candidate  areas will likely  be identified by
 the presence  of a  large number and variety of potentially
 polluting sources that have  been in operation over a number
 of years.   In some cases, all or a  portion of the sources may
 no longer  be in  existence,  however,  residual contamination
 remains.     In  any  case,  the  contamination  should not  be
 traceable to a  single source.

      It is  critical  to recognize  the  difference  between  an
 untreeitable plume,  a concept  irrelevant  to classification,
 and untreatable  ground  water which receives  the  plume,  a
 relevant  classification  factor.     An   example   of   a
 contamination plume  that can  be  traced back to  a specific
 activity  is shown  in Figure 6-2.   The ambient  ground water
 is,  however, potable.    Under these conditions a  Class III
 designation should  not  apply.   Figure  6-3 shows another
 contamination plume,  however,  in  which  extensive  regional
 contamination is found that  is technically  and economically
 infeasible to  treat with  public-water-system technologies.
 In  the  latter   case,   a   Class  III   designation  may  be
 appropriate.

      In general,  ground-water  contamination due to  broad-
 scale  human   activity  is  characterized  by   multiple
 constituents.  Both constituent  concentrations and  the suite
 of constituents will also  vary from point to point.  Water-
 quality data  would  be  expected  to  show  the  presence  of
 relatively  high concentrations  of a  few  ubiquitous compounds,
 together  with  lover concentrations of  a  larger number  of
 other   constituent*.    The  most   commonly   reported  (i.e.,
 ubiquitous)  ground-water  pollutants  include  chlorinated
 solventsi  pesticide*;  miscellaneous hydrocarbons,  such  as
 gasolin«* metal*;  salinity; and radionuclides (USEPA, I985a).
 The  entire ground-water  unit being   classified  does  not
 necessarily have  to meet Class III  untreatable criteria, but
 a  major  volume  portion  would.    The  definition  of  such
 significant portion is left to  the best  professional judgment
 of the  classifier.

     The water-quality data base, collected in support of the
 Class  III  determination,  should  reflect the  full spatial
variability  of  the various constituents, both vertically and

                              6-7

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                      FIGURE 6-2


EXAMPLE OF  CONTAMINATION THAT  SHOULD NOT QUALIFY
             FOR CLASS III  DESIGNATION
                              CONTAMINATION
                              PLUME FROM
                              ACTIVITY
                                        CLASSIFICATION REVIEW AREA
                                               BOUNDARY
          FACILITY  / ACTIVITY


          OftOUMO WATER UNTREATABLE  USINO METHODS  REASONABLY
          EMPLOYED IN PUBLIC WATER SUPPLY SYSTEMS..CONTAMINATION
          DIRECTLY RELATED TO ACTIVITY.
                          6-8

-------
                FIGURE  6-3

EXAMPLE OF CONTAMINATION THAT MAV
        FOR CLASS  III DE8zS£Tx55
                                                 AREA
FACILfTV /  ACTIVITY

               6-9

-------
horizontally.     The  Boat  useful  monitoring  network  for
determining   ambient  conditions   would  employ   a  sampling
pattern  that minimized  interdependence between  samples.    A
monitoring  network  intended  to  determine  a  specific  plume
geometry  will   rarely   suffice   to  provide  full  spatial
representation across  the ground-water unit.

     The degree  of uniformity of the sampling pattern can be
measured using the  statistical methods of  quadrant analysis
and   nearest-neighbor  analysis.     Quadrant  analysis   is
performed  by dividing the area  under consideration  into  a
number  of   equal-sized  subareas,  such  that  each  subarea
contains a number of sampling points.  If the data points  are
distributed  uniformly, each subarea  should  contain the same
number  of  points.   The  alternative to  quadrant  analysis  is
nearest-neighbor  analysis which is performed on the distances
between  sampling  points.  For a  more detailed discussion of
statistics  used  to  analyze  uniformity, see  "Statistics  and
Data Analysis in  Geology,1* (Davis, 1973).


6.3.2    Standards and Criteria for Treatment


     Both tests  for defining Class III based on treatability
imply  that  analyses  of treatment  methods  should consider
relevant standard* and criteria  for long-term drinking-water
use.    No  one  set  of  numbers  is  available and  thus some
professional judgment  may be required.

     EPA has issued National Interim Primary Drinking Water
Regulations   (NIPDWR)  under  the  Safe  Drinking  Water Act.
These regulations  set  maximum contaminant levels  (MCLs) for a
number  of   inorganic,   organic,   and   microbiological
contaminants  in  drinking water.   These values are based on
both health factors  and  technical/economical  feasibility.

     In  addition  to MCLs,  which are  enforceable standards,
maximum contaminant  levels goals  (MCLGs) are set, reflecting
EPA's goal of no  known or anticipated adverse health effects.
Both MCLG and MCL values are updated periodically.  EPA also
provides drinking-water  suppliers with additional guidance.
Under the  authority of  the  Safe Drinking Water  Act,  EPA is
now  in  the  process  of  developing  MCLGs  for  additional
contaminants  to   serve  as  guidance   for  establishing  new
drinking-water MCLs.  The Agency is accelerating the pace of
both MCLG and MCL issuance.   For current MCL and MCLG values
contact- the Agency at  the following address:

     The U.S. Environmental Protection  Agency
     Criteria and Standards Division
     Office of Drinking  Water (WH-550D)
     401 M Street, S.W.
     Washington,  DC  20460

                             6-10

-------
      Other constituents may be  intermittently  encountered in
 a water system, and are believed to pose a risk, yet are not
 currently the subject of any MCL or MCLG.  some  of  these are
 addressed  in the  form of  Health  Advisories.   The Health
 Advisories are  not mandatory  for  public-water  systems, but
 provide  information  for  emergency  situations.    They are
 calculated at  three exposure  levels:    1 day,  7 or 10  days,
 and longer  term  (1 to 2  years).   A  margin of  safety is
 factored  in  to protect  the  most  sensitive  members  of the
 general  population  (EPA,  1985b;  Federal   Register,  1985).
 They are  also  available  at the Office  of  Drinking Hater at
 the address .above.

      Finally, the RCRA program  in  developing  its corrective-
 action regulations  and in responding  to the  land-disposal-
 bans portion  of the RCRA amendments of  1984,  is examining the
 applicability of  other sets  of criteria and standards for
 both carcinogenic  and noncarcinogenic  contaminants.    These
 will likely be  useful  for addressing the large number of con-
 taminants without current MCLs, MCLGs,  or Health Advisories.
 Moreover,  to the  extent that EPA  develops  other  standards
 related  to  ground-water  or   drinking-water   quality,  such
 standards should be given appropriate consideration.
6.3.3  Overview of  Class  III  Treatability Tests

     The  first of two tests  presented  in  these Guidelines is
a  reference  technology  test, which  is a screening tool to
determine  if  techniques  commonly employed to  treat water
supplies  are  adequate   to  achieve  Federal  criteria  or
Guidelines  relevant to the contamination  found in  the ground
water.    This test  employs  a  relatively  simple decision
framework that does not involve detailed  engineering or cost
analyses.

     The  second test is an economic untreatability test. The
purpose  of this  test is  to  augment  the  screening tool by
assessing  whether  such technologies  would be economically
feasible.   This two-tiered technical and  economic  feasiblity
approach is discussed  in the  following  sections.
6.3.4	Reference Technology Screening Test	


     Water-treatment  technologies can  be categorized at any
point in time to  fall  into  one of three categories:
                             6-11

-------
     •  Methods  then in common use in public water-treatment
        systems.

     e  Methods  than known to be  in  use  in  a  limited  number
        of  cases  or under  special  circumstances in  public
        water-treatment systems.

     •  Methods  not  then  in  use  in  public  water-treatment
        systems.


     At this time, methods in the first category (common use)
are as follows:

     e  Aeration                 e  Chlorination
     e  Air Stripping           e  Flotation
     e  Carbon Adsorption        e  Fluoridation
     e  Chemical Precipitation   e  Granular Media Filtration
     Methods  in  the second category, known to be used  under
special circumstances at this time include:


     e  Desalination (e.g., reverse osmosis,  ultrafiltration,
        and electrodialysis).

     e  Ion exchange.

     •  Ozonation.

     •  Granular  Media  and  other  simple  point-of-use  and
        point-of-entry technologies  made  available  typically
        by water utilities on a short-term basis to a limited
        number of consumers.
When considering the application of  these  technologies,  the
classifier  should also  consider the  treatment  efficiencies
given  in  Table  6-1  and  the treatment descriptions given in
Table   6-2.     Soae  technologies,   for   example,   may   be
appropriate  for  minor  concentrations of  contaminants  and
inappropriate   for  larger   concentrations  of  the  same
contaminants.

     Treatment  methods  not now  believed   to  be  in  use  by
public water-treatment systems include distillation and wet-
air  oxidation.    These methods  are  considered new to water
treatment,  although  they  have  been  applied  for industrial
purposes in the  past.
                             6-12

-------
                                                                              IABIE 6-I
                                                 tCPGRKO TVPICAUV ACHIEVEA81E CONTAMINANT REMOVAL EFFICIENCIES   •. b
i
i
Arsenic . :
Bariu* :
ieruene • :
Cadaiue :
Carbon Tatrachloride
Chlordarw
Chrosriiai Ml
1.1-Dichtorocthylene
1.2c Dlchloroethylene
1,2t Dichloroethylone
Dich lor one than*
2.40
p-Dioxane
Endrin
Ethyl en* plycol
flow-ids
Formaldehyde
n Hexane
lead
lindsne
Mercury
Methyl Ethyl Ketone
Nitrate
PCI
Selenius
Silver
TetrechlcToethylene
Toluene
loxaptiew
1 , 1 . 1 • Tnchloroetherae
f r i ch 1 or aethy 1 ene
2.4.5-TP
Trihaloettthanes
Xylenes •
Air Stripping
Ml Aeration
Oc
0 c
98
0 c
96
Good d
Oc
98
97
n
80
Poor •
0 c
0 c
Good d

Good d
99
0 c
Oc
0 c
99

0 c
0 c
0 c
98
9$
Good d
ao
90
Poor d
75
99
Carbon
Adtorpt ion
50
30
75
as
Moderate d
Good d
95
97
70
95
70
Good d

99
Good d
0


95
95
90

15
IS
10
25
99
75
99
99
Poor d
Good d
99

CheBJcal
Precipitation
65
M
70
90
95
'
98
98

30
60
Good d



75


65
Good d
80

96

70
70
95
75

50
60

95
90
Desalination
95
95
75
60


90



15







60
65
90

70

97
40
80
SO

98

Good d
AO
80
flotation
45


60
75

50



40







98
85
75


97

45
30
40



Good d
80
97
GranuUr Media
Filtration
60
70
40
70
90
40
50
55
90

40




30


SO
50
55

10
20
60
20
0
65

97


60
75
Ion
Exchange
99
95

99


9o











97



90

98
99






SO

Ottmetion

o
97










Moderate d




30



SO

99

40







a  Data represent the percent of contaminant which can be expected to be removed tram solution using treatment sysicn tlailar to those currently inttalled  in
   full scale or pilot scale uater treatment operations.  Percent reaoval is oeneraled from available literature e* listed at the end of this section,  and are
   rounded to the nearest 5 percent (below 95 percent).  These maters are representative of achievable efficiencies,  and are not absolute indicators of specif
   system treatawnt efficiencies.
b  Blanks indicate that no data were reported in the available literature.
c  Although reported data were unavailable, the physical nature of those contaminants precludes effective removal via air stripping.
d  Only qualitative data were available in the literature.
1C

-------
          Tabl. 6.2
OEscximoH or TUATWTT raoczss

: ADVANTAGES
: Low Optra 1 and OUt
; High raeoval *fflclanclas tor tomm
: eencanlnanti
: Pracraacoant I* generally not
: required for (round water
: Cqulpcent purcha*ed off the (half


ADVANTAGES
Low eneriy requlreaMnti
High r«movtl *fflclencle* for *
vide rant* of contaalnant* ov«r
• broad concentration range


ADVANTAGES
Equipment t» readily available and
•a»y to operate
Low energy requlrieMnia
: Low capital and OUt eoiti


ADVAHTACtS
Ejce«H«ot tmmaml or nh«raa«l
anloa* and eattoo*
Goad r«*ovat. at high •nlarttaT
wal^ht orcanie*
Effactlv* trcauwnt far raawral
of dii»olw«d (Oiida
Air Strtpplac/Aaratlon
OISADVAVTACES
T««p«iratur« tan«lclv« (cold)
rnnraalniim
Ma7 raault la air pollur'an ar a na
na«d for billion Control

Carboa Adaorpcloo
DISADVAFTACB1
Mana««ta«nt of *p«nt carbon can ba
•xpanjLva and problaaatle
-Racanaratlon
-Dlspoaal
-Raplaca*ant
ai»h capital and ooaraetn« eo«t*

Chaaileal Praelplcatlon
OISADVAJITACIS
Q«n«var*« oaaoil*. ultraf llcraclon
DISADVARACXI
•l«b anaur roqulraaxnt*
l«qulc** aartaxuton pilot aa*lr»ai
for aa*h afttaa
Il«hl7 e«phl»tloatad Ina-truBanta-
tlon and control
C«o«racaia • eoneantratod brlna
which m*j r«qulro craataant
Pratraatawnt alaoat alway* raquir«d
Bltn capital and 04M ee«t»

LIMITATIONS
Riaav«f only volatile eontaalnanta
Su»p«idad aollda in Influant aaf
laad to raaoval ttfieitner It,**
dua to biological growth
(air atrtpplnc only).


LIMITATIOHS
For organic* ranoval whara eaneantra-
tlooi ara high, fraquant carbon
raganaration naeanary
Su*pandad tollt should not ajicaad
SO a«/U
Oil and graaaa ahould net axeaad 10 mg/L
Kaqulraa icaady hydraulic loading!


LIMITATIONS
Fraquant laboratory taatlng If raqulrad
to Balntaln high afflelanela*
pB dapandant
Ho eonoantratlon llalt

:
.
!
LIMITATIONS
:
: Suapamdatf aallda amiat ba low to pravant
foul la*
: OpacatiA* taagt«ratur«« mat ba batwaan
: 43 and «3 F
;
:
:
:
:
                 6-14

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       Table 6.2 (Cone.)
DESCRIPTION or TREATMENT mociss

ADVANTAGES
Highly reliable
Relatively *Lta>lei easy to oparata
•ad control
Multiple oadla can be uaed to laprove
«£f lcl*nele»


ADVANTAGES
Synthetic realm can tolerate • vlda
range of temperature and pi
Can reaove a variety of cat tonic and
aalonlc Inorganic and organic
eontaaloanta
Low aaargy reo^ilreaMnti .


ADVANTAGES
Reduce* chaalcal raalduala |«earatad
(particularly trlttalrmarhanaa)
No dl»««lv»d «olld» •«o«ratl bchaaf*
DI5ADVAHTACIS
Hl|h !**•! of training nac««hould not
ascaad 200 o«/L
Pratraataant «ay IM raoulrad If
*oap«n4ad tellda axcaad 100 o«/L


LIMITATIONS
Influant concent ratlaoi «houid aot
•«c««tl 4,000 ag/L
OK ihould not aieaad 10 mg/L
Influant should not contain chamlcaL
ojildaata (a.g., osona)
filtration la required aa pretraataant
If auapandad aalldt encaad 20 ag/L
In tha Influant


LIMITATIONS
Traaea only eontaailnanti which can ba
i»ldl»ad
Ooaa not raanva Iron-eyanlda cooplaxea


LIMITATIONS
Harrow ranca af raaoval - e.g., not
affactlva for aontaalnants vlth
daaalty greater than that of watac
t
        6-15

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      The  technologies currently used for treating surface and
 ground  water that serve as public drinJcing-water supplies can
 be  classed  into  five general categories:


      •  Volatile organic chemical removal.

      •  Non-volatile organic chemical removal.

      •  Metals removal.

      •  Non-metallic inorganic chemicals removal,

      •  Disinfection.


 Some  technologies are  effective in reducing only a few types
 of  contaminants, while other* may  efficiently treat several
 contaminant classes  simultaneously.   Although most processes
 are designed  to treat a  single class  of  contaminants,  many
 will  remove other types  of contaminants.   Brief descriptions
 of  several  generic  treatment  technologies and  the applica-
 tions are provided in Appendix C-l.

     Although most of  the  reference technologies noted above
 are   currently  in   use  at  public  water-supply  systems
 throughout  the   country,  not all  necessarily  remove  toxins
 (e.g.,  carbon adsorption  is  sometimes used in taste and odor
 applications and not  for  removal of volatile organics).   The
 exceptions  are   desalination,  ion  exchange,   and  ozonation;
 these  treatment technologies  may  be  considered  reasonably
 employed  in certain circumstances,  as  noted  above.    Air
 stripping, which is  most often used  for  removal of volatile
 organic solvents from  ground waters,  should  b«  considered
 available for Claas  III  analyses,  despite its limited use in
public water-supply systems.

     Distillation  techniques  have  long   been employed  for
treating  industrial  process  water,   for  example,  but  are
generally reserved for areas such as  islands, where potable
water is  scarce.  Biological treatment techniques have been
used  for  in-situ  cleanup of  ground  waters  rather than to
 treat  supplies  for  general  water  distribution.  Wet  air
 oxidation techniques are currently used primarily in industry
 for removal of organic* from process wastewater.

     A  partial  bibliography of  resources  and references to
 assist in treatability analyses is given in Appendix C.2.

Treatment Efficiencies

     Evaluation  of  treatment   efficiencies  for  a  single
contaminant or group of contaminants requires the  evaluation
of  interferences and interactions  of contaminants.  General

                             6-16

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 background data on  treatment  performance indicate ranges of
 values  for efficiency.    For  example,  EPA's Treatability
 Manual  for   Priority  Pollutants   (EPA,  1980a),  presents
 examples  of  typically  achievable,  contaminant-removal  ef-
 ficiencies for a range of  contaminants  and technologies.

      More  precise  determination  requires pilot  testing or
 comparison by  experts with '-'•her similar  waste streams.  The
 general  level  of success  the  various treatment technologies
 have with  frequently encountered contaminants  is indicated in
 Table 6-1.   Removal  efficiencies are  not reported  in the
 literature for all  contaminants, as  experience using certain
 treatment  technologies for  removal  of  some  contaminants is
 limited.

      Contaminant  concentration,  physical conditions   (e.g.,
 pH,  temperature),   solution  chemistry,   and  the  presence of
 competing  or  interfering  contaminants  can all contribute to
 the   large variations   in  removal  efficiencies  that  are
 reflected  in the literature.   For situations in which a more
 accurate assessment  of treatment  efficiencies  is desired, the
 user of  these Guidelines  may  wish to  consult the reference
 sources listed in Appendix C.2.

      Some   of   the   major  advantages,  disadvantages,  and
 limitations associated with each  treatment process are listed
 in Table 6-2.   It is  important to know the composition of the
 ground  water  to  be treated  in  order  to  develop  process
 configurations.     Evaluation   of  potential  interference
problems and matrix effects is  critical for  some scenarios.
 If a system uses both granular media  filtration  for solids
removal  and ion  exchange  for  softening,  for example,  the
 filtration  stage  should precede the ion-exchange stage in
order  to  assure  that  potential  resin-fouling  solids  are
eliminated from suspension.  As another example,  plants with
solvent  contamination will  commonly use  air stripping or
carbon adsorption to remove the  organics  prior to chlorina-
tioh  to prevent the formation  of halogenated organics,  which
are  less efficiently removed.   The examples  discussed  above
are  only  two  of a  very large number  of  potential  chemical
interactions that  may  interfere  with   the  removal  of  con-
taminants and affect the treatment process configuration for
a given condition.   These  factors must  be considered and are
likely to  require professional judgment to properly evaluate
the potential  for treatment of contaminated ground water.

Example   Procedures  for  Conducting   Reference  Screening
Technology Tests
     One approach  which can be  used in  this  screening test
involves five steps:


                             6-17

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      1.  Describe the contamination problem.

      2.  Determine the desired  effluent quality.

      3.  Define and assess process configurations.

      4.  Evaluate treated water quality.

      5.  Determine if desired water quality is met.

 Each  of  these  steps is described in detail below.

      Step  l;   Describe the Contamination Problem

      A description of the contamination probl »r might include
 data  on  the natural  or background  water quality, the extent
 of  contamination, and  the physical  factors  influencing both
 ground water and treatment.  The natural quality of a ground
 water may  be  inferred  from historical  data  or by comparison
 to background  ground waters in the site vicinity.

      Contaminants in the ground  water of concern  will then
 typically be specified and the range in concentrations noted.
 In particular, if the  type and  concentration  of contaminant
 vary  spatially,  this may be indicated,  as this variance has
 design  implications  for  treatment  configurations.
 Presentations  of analyses used and  the range of sampling and
 measurement  errors  included  would  assist  the  reviewer  in
 understanding  the degree of certainty of  contamination.   It
 is important to address the areal extent of contamination to
 be sure  it meets  the basic notion  that contamination is not
 related to an  individual facility or activity.

     The physical  parameters  of concern  include  flow pat-
 terns, climatology,  and other  site-specific  issues.  Many of
 the treatment  processes  are highly  sensitive  to temperature
 fluctuations.    Ambient  temperature  ranges,  therefore,  are
 important  in  selecting appropriate technologies or  housing
 requirements.   The climate in  the area of concern,  including
data  on  the  freeze/thaw cycles,  and any storm  or wind events
that  nay affect  the  treatment processes,  must also  be con-
sidered.  Other  site-specific   considerations  may  become
 important, on a case-by-case basis.
     To determine the  desired quality of  the  treated water
following completion of all  .reatment processes,  acceptable
target concentrations are established for  each contaminant.
Relevant  Federal  criteria include  the MCL,  the MCLG,  the
longest-term  Health Advisory  for each contaminant,  and any
other  appropriate  standards  or criteria  developed  by EPA
relating to ground-water or drinking-water  quality.

                             6-18

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           3? - Define and Assess Available Process  Configura-
     tions

     The classifier then typically defines a set of treatment
process  configurations  that  may  be   used  to  remove
contaminants  from   the  ground  water.    These  process
configurations  would   be  developed  considering  efficient
contaminant  removal   to  the  minimum  level required.    The
technologies selected  would  then be assessed based on  their
current and projected near-term future availability.

     Step 4;  Evaluate Treated Water Quality

     To evaluate  typically achieved water  quality using any
given  treatment  process configuration, the  concentration  of
specific contaminants in the ground wacer/ influent, levels  of
background water-quality  parameters  (pH,  TDS, etc.)/ and the
removal efficiencies of each contaminant using each treatment
process should ideally be known.

     Background data and/or manuals on treatability developed
by  EPA can  be consulted  for  initial guidance  on treatment
(e.g.,  EPA 's  Treatabilitv Manual  for Priority  Pollutants.
        Contaminant removal efficiencies for common treatment
technologies are  presented in Table 6-2.  A qualified  water
treatment  engineer  could  also   determine  the   relative
contaminant  removal  effectiveness  due/  for   example,   to
interference effects.

     step 5:  Determine If Desired Water Quality Is  Met

     Once  the  approximate  effluent concentration  of  each
contaminant has been evaluated for a given treatment process,
these  can  be  compared  to  the  appropriate  water-quality
standard.   If  ail effluent concentrations are  less  than the
desired  water  quality, the  ground  water  can be cleaned  up
using treatment methods reasonably  employed  in  public water-
supply systems.  Thus, a Class II determination  is warranted:
If  some  effluent contaminant concentrations exceed desired
water quality,  the  treatment process configuration  does  not
adequately  clean  the  ground   water,   and   an  alternative
configuration   should   be  evaluated  for   contaminant
treatability.  Zf all available  treatment process configura-
tions do not  remove contaminants  to the levels that  meet
desired vater quality, the ground water  cannot  be cleaned up
using treatment methods reasonably  employed  in  public water-
supply systems; these units will then be candidates  for  Class
III.  •

     Hypothetical Example

     The following example is illustrative  in  nature and is
not meant to represent conditions at any specific facility.

                             6-19

-------
      A permit, applicant has asked to site a facility and has
 made the claim that the site location will only affect Class
 III  ground water.   The chemical contaminants  in  the ground
 water,   listed  in  Table  6-3,  are  apparently  from  multiple
 sources and occur throughout  the Classification Review Area.

      For trichloroethylene,  carbon tetrachloride,  cadmium,
 and   selenium,  the  applicant  defines the  desired  maximum
 effluent contaminant concentrations to be equal to  the MCLs
 for  those constituents.  For  tetrachloroethylene, a long-term
 Health Advisory was  used.

      The  treatment  processes  that   most  readily  remove
 volatile   organics,  such   as  carbon  tetrachloride  and
 tetrachloroethylene,   include   carbon adsorption  and  air
 stripping.    Metals, such  as cadmium  and  selenium, can  be
 removed using chemical precipitation, desalination,  and ion
 exchange.     Granular  media  filtration  would  probably  be
 considered  for   removal   of  residual particulate  matter,
 following  a  chemical  precipitation  step,  particularly  if
 desalination,  carbon adsorption, or ion exchange processes
 followed.   All of these processes  are currently in use  in
 public  water-supply  systems.

     Achievable effluent  quality must be evaluated  for each
 treatment process configuration  to determine if  the ground
 water  can be  treated to meet desirable levels.   Process and
 contaminant specific removal  efficiencies  are  provided for
 all  five contaminants.   (Please note:  these  values are  to
 illustrate  the process  and  are not  intended  to be actual
 efficiencies.)    As  indicated by calculated WQO  values and
 comparing them with  WQ^ values  (Table 6-3), treatment process
 configuration A  can result  in  removal of trichloroethylene,
 tetrachloroethylene,  and  carbon  tetrachloride,  such  that
 acceptable  levels are achieved.  However,  levels  of cadmium
 and  selenium, following treatment using process configuration
A  cannot meet  the  desired water  quality.   Therefore,  the
 applicant  must   consider  an additional  treatment  process
 configuration.

     Removal  efficiencies  for  the  process configuration  B
 including air stripping,  chemical precipitation, filtration,
 and  desalination  can achieve acceptable water-quality levels
 for  all contaminants.   Thus, according to  this methodology,
 this  ground  water is  technically treatable  using treatment
method* reasonably employed  in  public water-supply systems.
 In  this  situation,  therefore,  the economic  untreatability
 test   should   be   applied  to  determine  whether  treatment
configuration B would be economically feasible.
                             6-20

-------
                                                                               TABLE 6-3

                                                          EFFLUENT QUALITY WORKING TABLE FROM SAMPLE PROBLEM
Conta»inant
Process Conf inure! ion A
Trlchloraethylcmi
Tetrachloroethylene
Carbon Tutrachlorlde
CadMiUH
Seleniuat
Process Configuration B
Tr ichlorcethy lene
Tetrachlcroethylene
Carbon Tetrachloride
Cadmus
Seleniuai
«%»
0.6
150.0
40.0
0.5
2.0
0.6
150.0
40.0
0.5
2.0
«tf
0.005*
1.9
0.005*
0.01
0.01
0.005«
1.9
0.005*
0.01
0.01
Treatment Process Reaoval Ef t ictenciesc
Process A Process B Process C Process 0 Process E Process f
Air Stripping Cheatcal Prectp. Filtration
98 60 7
98 95 0
98 95 90
0 90 70
t
0 70 60
Air Stripping Cheaical Precip. Filtration' Desalination
98 60 77
98 95 0 80
98 95 90 7
0 90 70 60
0 70 60 97
wQ0d
0.004
O.IS
0.004
0.015
0.24
0.004
0.01
0.004
0.006
0.007
Desired Water
Quality Achieved?
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
I
N>
        " WQj - the Influent conta»inant concentration, in •*/!


        b WQd « the desired iMiisjua effluent contaminant concentration, in


        c BesM>wal efficiencies report  in percent


        d WQ0 * the calculated effluent contaminant concentration,  in mg/1


        e These MCLs are effective January 9.  1989

-------
 6.3.5    Economic Untreatability Test
      The economic test has been developed to identify ground-
water sources that have particularly  low economic value under
present or foreseeable  future conditions.   Water sources of
low value are defined as those where  future treatment and use
of  such  ground waters  for drinking purposes would  be very
costly and  thus highly  unlikely.    This  definition  implies
that  ground waters may be considered to be of low value even
though there may. be  technical procedures available to render
these water sources drinkable  (i.e.,  procedures identified in
the   reference  technology  test) .     Ground  waters  with
particularly   low  value  nay  warrant  a  lower  level  of
protection than other ground waters.

      As with  the  econoaic irreplaceability  test used  for
class I determinations,  the economic untreatability  tes.t is
based  on  t -pical  per  household  costs  of  drinking-water
supplies.     Total  water-supply  system  costs  are  again
estimated for  a user  population  and  then  compared  against
threshold values to gauge economic feasibility.   The process
for applying the economic untreatability test, therefore, is
generally  consistent  with  the  economic  irreplaceability
methodology.

      The  Class  III  economic  untreatability  test,  however,
differs   from   the  economic irreplaceability  test  in  two
respects.   First, the  economic untreatability test is based
on a  hypothetical drinking-water system because  a Class III
candidate  ground water by  definition is  not currently used.
Second,  the  Class  III untreatability test  is  designed to
emphasize  the  ground-water treatment costs  of  the  supply
system  while the  Class I test considers all  types of costs
equally.  The  Class  III test is constructed in this manner to
ensure  that ground water that  meets both the technically and
economically   feasible   treatment   criteria  will  not  be
classified  as  Class  III.

      Because   of  these  dissimilarities  with  the  class  I
economic  irreplaceability test, the  economic untreatability
test*   involves  four  steps  rather  than  three,  with  the
addition*!  step being  the  estimation of  a hypothetical user
population size.

      Thsv four steps for applying the economic untreatability
test  arc  as follows:


      1. Estimate the hypothetical user population  size.
      2. Estimate the hypothetical system cost.
      3. Calculate the economic untreatability  thresholds.
      4. Apply  the economic untreadability test.

                             6-22

-------
 Each of these step* la described  in detail below.
 step 1;   Estimate t;ha Hypothetical User Population Size

      The first step in the economic untreatability test is to
 estimate the  size of  the  hypothetical user population that
 could potentially  use the  ground  water  as  a  source  of
 drinking water.   The size  of the hypothetical user population
 should be determined  as the population  that could be served
 by the maximum sustained yield of the aquifer in question.

      A number  of data sources are  available . for estimating
 the yield of  an  aquifer.   The U.S.  Geological Survey office
 (e.g., District Office) in the State or the State geological
 or water surveys will  often have hydrogeological information
 (e.g., maps,  reports, and surveys)  on most aquifers within a
 state.  Consultation with  these sources and other individuals
 with  local  expertise  and experience can likely provide  a
 reasonable  estimate  of an aquifer's  sustained yield.   For
 more  detailed  assessments,  a   review  of  boring  logs,
 geotechnical   evaluations   or  other  data sources  will  be
 needed.   Field assessments and ground-water monitoring also
 may be needed to  assess not only  aquifer yield, but quality
 parameters as  well.

      Once  the  sustained  yield  is  estimated,  a  population
 equivalent can be determined based on a per capita water use
 of 100 gallons per day, which  is  roughly equivalent to a per
 household  water   use  of  100,000  gallons  per year.    For
 example,  geotechnical and  hydrogeological data may indicate
 that a ground-water  source that  is being classified  has an
 estimated  sustainable yield of  50 gpm or 72,000 gpd,   The
 population equivalent that could be served  by this  yield is
 720  (72,000 gpd divided by  100 gpd/person).

 Step 2;  Estimate  the  Hypothetical System  Cost

      The  second step of the economic untreatability test is
 to  estimate)  the cost  of the ground-water supply system that
 could serve)  the  hypothetical  user population  determined in
 Step 1.    This test  is  structured  around  the four  major
 component* of water-system costs:    acquisition,  treatment,
 distribution,   and  service.     As  with  the   economic
 irreplaceability  test methodology, Appendix D  presents  the
 cost-estimating  methodology to  assist   in  conducting  such
 analyses.

      Note that because the primary focus  of this test is the
treatability of the ground water  under review, site-specific
treatment costs  should be  used in  all  cases when estimating
the  total  system  cost.   Moraovsr,  the treatment  costs used

                            6-23

-------
 should be  based on  the  least expensive of  all technically
 feasible  treatment trains.   With regard to appropriate costs
 for the remaining  components,  the  default  (i.e., nationally
 typical)  values presented  in Appendix  0  for  acquisition,
 delivery, and service are provided  for assistance.  Even if a
 typical regional cost estimate  is used in lieu of the typical
 national  costs   given in  Appendix  D,  extreme  costs  for
 acquisition,  delivery, and  service generally should  not  be
 used  in  ordar to ensure that tti« results of the treatability
 test  primarily reflect the costs of treatment rather than the
 costs of other system components.

 Step  3.  Calculate  the Economic ffntreatability Threshold

      The third step of the economic untreatability test is to
 calculate  the  threshold  against   which  the annualized  pejr
 household water-supply system cost  will be compared.  As with
 the Class  I  economic irreplaceability  test,   and for  the
 rationale noted  in  the  economic  irreplaceability discussion
 in  Chapter  4, the  threshold that should  be  used for  a given
 classification  is   the   ninetieth  percentile  of  household
 water-supply   cost   for   water  systems  serving  populations
 similar  in  size to  the  hypothetical user population.   The
 methodology  for  calculating  this   threshold  is  presented  in
 Appendix  D.   For reference,  Figures  4-5  and 4-6 (in Chapter
 4)  graphically illustrate this  cost function  for system sizes
 ranging  froa  500  to 1,000,000 persons  and  500  to  10,000
 persons, respectively.

     As noted in Chapter  4, the Agency is currently reviewing
 the question of  community water-supply  system affordability
 which  may  lead  to  future   changes  in  the way  Class  III
 assessments are  performed.

 Step  4.  Apply the  Economic Untreatabilitv Test

     Having   estimated the  size  of the hypothetical  user
 population,  the  annualized total cost of providing water to
 that  population  given site-specific  treatment requirements,
 and the appropriate ninetieth percentile threshold, the final
 step  of  the  economic untreatability  test is to compare the
 estimated cost  of  the water-supply  system  to  the threshold
value  to   determine  whether  the  ground  water  could  be
 economically  treated and  provided to  a user population.

     If~ the  cost   of   the  hypothetical  water   supply
 significantly exceeds the  ninetieth percentile threshold,
then  th«  classifier nay  conclude that  the costs of treating
the ground water would make  the viable use of that water for
drinking  purposes   highly  unlikely.    The  ground  water,
therefore,  is not  a potential source of drinking water and
should be classified as Class III - Economically Untreatable.
Further, the  classifier should  proceed to the next  section of


                             6-24

-------
 this  chapter  in  order  to  determine   in  which  Class  III
 subclass the ground water belongs.

      If  the   cost  of  the  hypothetical  water  supply  is
 significantly  less  than the  threshold, then the  cost  of
 treating the  ground water would not make the  total  costs of
 using  the  water  for  drinking  purposes   economically
 infeasible.  Because the ground water is capable of providing
 a  sufficient  yield and is both  technically and economically
 treatable,  it, therefore, represents a potential source of
 drinking water and should be classified as Class IIB.

      Finally,  if  the cost of the water supply is relatively
 close to the  threshold, then the classifier should  consider
 the variability intrinsic in  the function used to derive the
 ninetieth  percentile  thresholds   and  make  a   final
 determination  based on best professional judgment.
6.4     Subclasses of Class III
     The subclasses  of  Class III ground water are  differen-
tiated  in  part  by  the relative  degree of  interconnection
between these waters and those in adjacent ground-water units
and/or  surface  waters.   A discussion of ground-water units
and the concept of degrees of interconnection are provided in
Chapter Three.   The  subdivision of Class III  into A  and  B
designations  provides  further  definition  of  the  relative
potential for contaainant  release  incidents  to  significantly
reduce the quality and value of a valuable water resource.

     Subclass IZIA  ground-water units are defined  as  having
an intermediate degree: of interconnection to  adjacent ground-
water  units  and/or are  interconnected to  surface  waters.
Subclass IIIA is  also  associated with shallow,  naturally
saline ground water within a single ground-water unit that is
continuous throughout  the  Classification  Review Area.  Note
that all Class  ZZZ  designations based on  insufficient yield
are considered Class ZZZA regardless of interconnection.

     As  mentioned   in  Chapter  Three,  a   high  degree  of
interconnection is  inferred when the conditions  for a lower
degree  of  interconnection   (low:   Type  2   boundary  or
intermediate: Types  1,  3,  and  4)  are  not demonstrated.  High
interconnection  of  waters  is  assumed to  occur  within  a
ground-water  unit  and  where  ground  water  discharges  into
adjacent  surface-water  bodies.    The  latter  situation  is
especially  relevant  in  identifying  Subclass  IZZA  ground
waters.
                             6-25

-------
     Subclass  IllB ground-water units are defined as having a
low  degree of interconnection to ground-water  units  within
the  Classification  Review  Area.    Generally, Subclass  IIIB
excludes  (1)  unconfined and  eemiconfined  ground-water units
as well  ae (2) extensively confined ground-water units under
natural  conditions  where  substantial  numbers of improperly
cased  and/or   sealed  wells   significantly  compromise  such
confinement.    Note  that the  low degree  of interconnection
criteria  includes, but is  not limited to the interconnection
criteria  for  Class  I  injection wells  as regulated under the
Safe Drinking  Water  Act.

Examples  of Class IIIA Ground  Water

     Two  examples of  Class IIIA  ground-water conditions are
provided.   The first  example concerns an area  with ground-
water  contaminated  due  to  broad-scale human activity.   The
second concerns shallow, naturally  saline  (TDS  greater than
or  equal  to   10,000 mg/L)  ground  water.    Note  that these
examples   are   extrapolated  from  a  knowledge  of  similar
settings, but  do not represent any specific  location or site.

     The  first example  of  Subclass IIIA  is associated with
shallow,  unconfined, aquifers that have been contaminated to
untreatable levels via broad-scale human activity.  Figure 6-
4 shows a hydrogeologic  setting with an urban/industrial area
located near a major surface  water and overlying an alluvial
aquifer with  a relatively shallow depth to  water.  The area
contains  numerous  diffuse  sources of contamination that have
degraded  ground-water  quality.  As shown,  the degraded water
comprises the  major  volume  of  the ground-water  unit that
discharges to  the local surface-water body.  A ground-water
unit  boundary was  identified  coincident  with  the  river,
thereby allowing subdivision.

     A  second  example of  Subclass  IIIA is associated with
shallow naturally saline ground water within a single ground-
water unit that is  continuous throughout  the Classification
Review Area.    In some  hydrogeologic  settings,   such  as the
closed basin/arid climatic setting illustrated in  Figure 6-5,
it is  possible that the extent  of  the  saline ground waters
could  be  very  large  compared  to  the  review  area.   The
Classification Review Area in Figure 6-5 represents  only a
small  portion  of  the  total extent  of  the saline  ground
waters.   By definition, the  saline  ground-water unit within
the Classification Review Area would be highly interconnected
to other  ground water  both within and outside the  review area
boundaries.    Under  the conditions  described,  the shallow,
saline, unconfined to  samiconfined ground water would  receive
a Subclass IIIA designation.
                             6-26

-------
                                               FIGURE 6-4


                       ALLUVIAL AQUIFER SEPARATED INTO TWO GROUND-WATER UNITS

                                 WITH HIGH  INTERCONNECTION TO A  RIVER
                                          CLASSIFICATION  REVIEW AREA
I
to
                          BEDROCK
                                EXPLANATION
                           71g|    UNTREATABLE WATER


                           	*.    GROUND-WATER FLOW DIRECTION


                           2._    WATER TABLE

-------
                                                   FIGURE 6-5


                              CLOSED BASIN/ARID CLIMATIC SETTING CONTAINING  A
                        CLASSIFICATION REVIEW AREA WITH A SINGLE  GROUND-WATER UNIT
Ok
i
KJ
-   GROUND-WATER FLOW DIRECTION


                             CRA    CLASSIFICATION REVIEW AREA

-------
 Example  of  Class IIIB Ground Water

     An  example of a Class  IIIB ground-water unit  within  a
 sedimentary basin  is shown in Figure 6-6.  Sedimentary basins
 commonly   contain  multiple   fresh-water   aquifers,   each
 separated  by  a   regionally   extensive  low-permeability
 confining  unit  (Type   2  boundary)  overlying deeper  saline
 water.    Figure 6-6  is  an  example  of such  a basin  where
 ultimate discharge of the deep fresh water through overlying
 low-permeability confining units  (flow barriers)  is to local
 steams/  the atmosphere,  and  the ocean.  Deeper ground waters
 in  these basins will be  characterized by  TDS concentrations
 that may be much greater than the 10,000 mg/L limit for Class
 III  ground  waters, and  interconnection is considered  to  be
 low, even though hydraulic gradients are in the direction  of
 less saline water.

     The  deep  saline  water  unit can be  considered to  be
 naturally isolated from overlying fresh ground-water units.
 The  reasons  for  the low degree  of interconnection are  as
 follows:

     •  The  flow  of  water  through  the  confining  units  is
        exceedingly small.

     e  Travel time through the confining unit is very great.

     e  There are  no significant  breaches  of confinement due
        to  improperly cased or sealed wells.
     Deep,  confined,  saline  ground-water units  with  a  low
degree  of  interconnection  to  overlying fresh  ground-water
units  are currently the  primary hydrogeologic setting into
which wells can be permitted to inject hazardous wastes under
present  EPA and  State Underground  Injection Control  (UIC)
regulations.  These waters  are encompassed  within Class III,
Subclass B ground water.
                             6-29

-------
                                                       FIGURE 6-6
                                    EXAMPLE  OF PROBABLE  CLASS  IIIB  GROUND  WATERS
I
ut
o
            „ CfttlTALLMC
          /  ,  •ASCMCNT
                *<*"  I
  INJCCTION     . ' - \ /
S  *Ul   \   /         \
               EXPLANATION
                     HIGHLY SALINE GROUND WATER
                     DIFFUSION ZONE
               S	WATER TABLE
                ——  GROUND-WATER FLOW DIRECTION
                CRA  CLASSIFICATION REVIEW AREA
                                                                                               GROUND-WATER UNIT A
                                                                                               GROUND-WATER UNIT 8
                                                                                               DIFFUSION ZONE
                                                                                               TYPE 3 BOUNDARY
                                                                                               GROUND-WATER UNIT C

-------
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     Liner Location Risk and Cost Analysis Model, Appendix C.
     Office   of  Solid  Waste,  Economic  Analysis Branch,
     Washington, D.C.

U.S. Geological  Survey, 1984.   National  Water Summary 1984.
     Water Supply Paper  2275.    United  States  Government
     Printing Office, Washington,  D.C.
                             B-3

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                          APPENDICES
     Three groups of supplemental informational materials are
appended for  the classifier's use.   The technical basis for
the  initial 2-mile  radius of the  Classification Review Area
is   discussed   in   Appendix  A.     Derailed  procedures  for
expanding or  subdividing the Classification  Review Area are
also provided.   Supplemental materials  for the non-economic
aspects of Class I  and Class III determinations are provided
in Appendix  B  and  Appendix  C,  respectively.   Supplemental
guidance for  applying  the common aspects of  the Class I and
Class III economic tests is provided in Appendix 0.

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                         APPENDICES
APPENDIX A:  SUPPLEMENTAL INFORMATION: CLASSIFICATION REVIEW
             AREA
APPENDIX B:   SUPPLEMENTAL INFORMATION FOR CLASS I PROCEDURES


APPENDIX C:   SUPPLEMENTAL INFORMATION FOR CLASS III
             PROCEDURES
APPENDIX D:   SUPPLEMENTAL INFORMATION FOR CLASS I AND CLASS
             III ECONOMIC TESTS

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                           GLOSSARY  *
 AQUIFER  - A geologic  formation, group of geologic formations,
     or  part of a geologic formation that yields significant
     quantities  of vater  to veils and springs.

 AQUIFER  SYSTEM - A heterogeneous body of intercalated perme-
     able  and less permeable material that  acts as a water-
     yielding hydraulic unit of regional extent.

 AQUITARO -  A confining bed that retards, but does not prevent
     the flow of water  to or  from an  adjacent aquifer; it
     does not readily yield water to wells or springs.

 CONE  OP  DEPRESSION  -  A depression  in the  POTENTIOMETRIC
     SURFACE of  a body of ground water that has the shape of
     an  inverted cone and develops around a pumped well.

 CONFINED  CONDITIONS  -  Exists  when an  aquifer  is  confined
     between two layers  of much less pervious material.  The
     pressure  condition   of  such a  system  is such  that the
     water  level in a well penetrating  the  confined aquifer
     usually rises above  the top of the aquifer.

CONTAMINANT  PLUME  -  Irregular volume  occupied by a  body of
     dissolved or suspended pollutants in ground water.

CRA - Abbreviation of Classification Review Area.

DISCHARGE AREA - A discharge area  is an  area of land beneath
     which  there is  a net annual transfer of  water from the
     saturated zone to a  surface-water body, the land surface
     or  the  root  zone.    The  net  discharge is  physically
     manifested by an increase  of hydraulic heads with depth
     (i.e.,  upward  ground-water  flow to  the water table).
     These*  zones may be  associated with  natural  areas of
     discharge  such  as  seeps,  springs,  caves,  wetlands,
     streams, bays,  or playas.

ECOLOGICAL  SYSTEM  (ECOSYSTEM)  -  An  ecological  community
     together with its physical environment.
     *  For general  information only — not  to be viewed as
suggested or mandatory language for regulatory purposes.

                             G-l

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 ECOLOGY - The science of the relationships between organisms
      and their environment.

 ECOSYSTEM - See ECOLOGICAL  SYSTEM.

 FLOW NET  -  A graphical presentation of  ground-water f ? ow
      lines and lines of  equal pressure head.

 GEOLOGIC FORMATION - A body of  rock that can be distinguished
      on the basis of  characteristic lithologic features such
      as chemical composition, structures, textures, or fossil
      content.

 GROUND-WATER -  Subsurface  water within the  zone of satura-
      tion.

 GROUND-WATER BASIN  - (a)  A subsurface  structure having the
      character of  a basin  with respect to  the collection,
      retention,   and outflow of water,  (b)  An  aquifer,  or
      system of  aquifers,  whether  or  not  basin-shaped, that
      has reasonably  well-defined  hydrologic  boundaries and,
      more or less,  definite areas  of  recharge and discharge.

 GROUND-WATER  FLOW  DIVIDE  - An  imaginary  plane  (or curved
      surface)  distinguished by the  limiting flow  lines of
      adjacent flow  systems.   Conceptually there  is no flow
      across this plane between  the flow systems.

 GROUND-WATER FLOW REGIME - The sum total of all ground water
      (water  within  the  saturated   zone)   and  surrounding
      geologic media  (e.g.,   sediment and rocks).   The top of
      the ground-water regime  is  the  water table  while the
      bottom would  be the  base of. significant ground-water
      circulation*   Temporarily  perched waters within  the
      vadose zone would generally  not  qualify as part of the
      ground-water regime.

GROUND-WATER FLOW SYSTEM  (GROUND-WATER SYSTEM) - A body of
      circulating ground  water  having  a   water-table  upper
      boundary and ground-water  flow divide boundaries along
      all other  sides.   These  boundaries  encompass distinct
      recharge and discharge areas  unique to the  flow system.

GROUND-WATER SYSTEM - See GROUND-WATER FLOW SYSTEM.

HYDRAULIC CONDUCTIVITY - The capacity of  earth materials to
      transmit water.

HYDRAULIC  GRADIENT  -  The change in STATIC HEAD per-unit-of-
      distance in a given direction.

HYDPAULIC  HEAD GRADIENT  - See HYDRAULIC GRADIENT.

PIEZOMETRIC SURFACE - See POTENTIOMETRIC SURFACE.

                             G-2

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 POTABLE WATER  - Water that  is safe and palatable  for  hunan
      use;  concentrations of  pathogenic organisms  and  dis-
      solved  toxic  constituents  have  been  reduced to  safe
      levels, and  it has been  treated  so as to  be  tolerably
      low in objectionable taste,  odor,  color, or turbidity,

 POTENTIOMETRIC SURFACE  (PIEZOMETRIC SURFACE) -  An  imaginary
      surface representing the STATIC HEAD of ground  water and
      defined by the level to which water will rise in a  well.
      The WATER TABLE is  a particular potentiometrie surface.

 RECHARGE AREA  -  A recharge area  is an area of  land  beneath
      which there  is a  net annual  transfer of water  through
      the vadose zor.a into the ground-water  regime.   The net
      recharge is manifested by a  decrease  in hydraulic  heads
      with depth  (i.e.,  downward  ground-water  flow from  the
      water table).

 SATURATED ZONE  - A subsurface zone in which all  the  voids are
      filled with  water  under pressure  greater  than that of
      the atmosphere.  This  zone  is separated from  the  over-
      lying zone of  aeration  (unsaturated zone)  by  the  WATER
      TABLE.

 STATIC  HEAD (HYDRAULIC HEAD)  - The height above  a datum  plane
      of the surface of a  column of water (or liquid) that can
      be supported by the  static pressure at a given  point.

 STRESS  (PUMPING STRESS)  - Drawdown  of water level and change
      in HYDRAULIC GRADIENT induced by pumping ground water.

 SURFACE-WATER DIVIDE  -  The   line  of  separation,  or ridge,
      summit,  or  narrow  tract of  high  ground,  marking  the
      boundary  between   two  adjacent   drainage   basins,  or
      dividing the surface waters  that  flow naturally in  one
      direction  from those that flow in the opposite direc-
      tion.

 TOTAL DISSOLVED  SOLIDS  (TDS)  -  The  quantity  of  dissolved
      material in a sample of  water determined either from the
      residue on  evaporation  by  drying at 180°C,  or,  for
      waters containing more  than  1,000 parts  per  million,
      fresjr the sum of determined constituents.
UNCONFIMED  CONDITIONS -  Exists when the  upper limit of  the
     aquifer  is defined  by the water  table itself.  At  the
     water  table,  water  in the aquifer  pores is at  atomos-
     pheric pressure.

UNSATURATED ZONE - See VADOSE  ZONE.
                              G-3

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VADOSE ZONE  (ZONE OF AERATION) - A subsurface zone containing
     water under pressure less than that  of the atmosphere,
     including water held by capillarity,  and containing air
     or gases generally under atmospheric pressure.

WATER  TABLE  -  The  surface  of a  body of  unconfirmed  ground
     water at which the pressure  is  equal  to  that  of the
     atmosphere.

WATER-TABLE  GRADIENT - The change in  elevation  of the water
     table per unit  of horizontal distance.
                             G-4

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                      TABT.E QF CONTENTS

                                                          Page


 APPENDIX A:  SUPPLEMENTAL  INFORMATION:   CLASSIFICATION
             REVIEW AREA	   A-l
  A.I   Technical  Basis  for Initial 2-Mile  Radius
        of the Classification Review Area	   A-l
     A. 1.1   Plume Survey	;	   A-2
     A.1.2   Distance to Dovngradient Surface  Waters...   A-4
     A. 1.3   Pumping Well  capture zones	   A-4
  A.2   Determining Expanded Review Area Dimensions....   A-8
  A.3   Subdividing the Classification Review  Area	   A-16
     A.3.1   Identifying Ground-Water Units and
             Analyzing Interconnection	   A-16
     A.3.2   Example of Subdividing a Classification
             Review Area	   A-35
  A. 4   Appendix A References	   A-40


APPENDIX B:  SUPPLEMENTAL  INFORMATION FOR CLASS I
             PROCEDURES	   B-l

  B. 1   Densely Settled Criterion	   B-l
  B.2   Use of GEMS System for Estimating
        well Density	   B-2
  B.3   General Background Information on
        Institutional Constraints	   B-3
  B.4   List of Offices of Endangered Species,
        U.S. Fish  and wildlife Services	   B-8
  B.5   List of State Natural Heritage
        Program Offices  (October 1985)	   B-14
  B. 6   Appendix B References	   B-2o


APPENDIX C:  SUPPLEMENTAL  INFORMATION FOR
             CLASS ZII PROCEDURES	   C-l

  C. 1   Overview of Treatment Technologies	   C-l
  C.2   Partial Bibliography of References
        evaluating Water Treatment Technologies	   c-7

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                  TABLE OF CONTENTS (CONTINUED)


APPENDIX D: SUPPLEMENTAL INFORMATION FOR CLASS I
            AND CLASS III ECONOMIC TESTS	   D-l
  D. 1   Components and Types of Costs	   D-l
     D.I.2   Cost Components	   D-3
     D.I.2   Types of Cost	   D-4
  D. 2   General cost Estimation Procedures	   D-5
     D. 2 .1   overview of Cost Estimation 	   D-6
     D.2.2   Methods for Estimating Costs	   D-7
     D.2.3   Final Cost Estimate	   D-12
  D.3   Cost Estimation for the Class I - Economic
        Irreplaceability Test	   D-l5
     D.3.1   Class I Cost Estimating Procedure.........   D-l5
     D.3.2   Hypothetical Example of Class I Cost
                Estimation.	   D-17
  D.4   Cost Estimating for the Class III Economic
        Untreatability Test	   D-18
     D.4.1   Class  III  Cost  Estimating
             Procedure	   D-18
     D.4.2   Hypothetical Example of Class III Cost
             Estimation	   D-19
  D.5   Derivation and Calculation of Economic
        Thresholds	 D-21
     D. 5.1   Derivation of Economic Thresholds	 D-21
     D.5.2   Methodology for  Calculating Econoaic
             Thresholds	 D-2 2
     D.5.3   Illustrative Applications  of Econoaic
             Thresholds	   D-2 4
  D.6   Appendix D References.	   D-26
                                ii

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                        LIST OF FIGURES



APPENDIX A
A-l.
A-2.
A-3.
A-4.

A-5.

A-6

A-7.

A-8.

A-9.

A-10.
A-ll.
A-12.

A-13.

A-14.

A-15.


A-16.

A-17.
Plume Length Distribution 	 	
Dovngradient Distance to Surface Water 	
Well Capture Zone 	 	
Hypothetical Karat Terrain with 2 -Mile Review
Area 	 	
Generalized Grose Section of a Karat
Hydrogeologic Setting 	
Example of Overflow Across Ground-Water
Basins 	
Hypothetical Xarst Terrain with Expanded

Hypothetical Example of Review- Area Expansion
in a Fractured Rock Setting 	
Hydrogeologic Sections Showing Flow Systems of
Increasing complexity with Type 1 Boundaries..
Example of Type 1 Flow Divide Boundary... 	
Example of Type 2 Boundary 	
Example of Type 3 Boundary Through an
Unconf ined Aquifer in a Coastal Setting 	
Example of Type 3 Boundary in an Evaporite/
Saline Water Setting 	
Example of Type 3 Boundary Through Basin Fill
in a Closed Basin/Arid Climatic Setting 	
Sacample of a Type 4 Gradient-Based Boundary
Defined on the Basis of Simulated Ground-Water
Plow Patterns 	
• Hypothetical Setting for Demonstrating the
Subdivision of a Classification Review Area..
Hypothetical Classification Review Area 	
A-3
A-5
A-6

A-10

A-ll

A-12

A-14

A-15

A-18
A-20
A-2 4

A-2 8

A-29

A-31


A-34

A-3 6
A-37
                               iii

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                    LIST OF FIGURES  ICOKT.)
A-18.    Subdivision of a Hypothetical Classification
         Review Area into the  Ground-Water Units	    A-38
APPENDIX D
D-l.     Ninetieth Percentile  Economic Threshold by
         System Size	    0-23
                        LIST OF TABLE?
APPENDIX A
A-l.    Lateral and  Dovngradient Well Capture
        Distance	    A-7
A-2.    Range of Values of Hydraulic Conductivity
        and Permeability	    A-26
APPENDIX D
0-1.    Components and Types of Water Supply System
        COBtS	    0-2
0-2.    Water Supply System Cost Worksheet	    0-8
0-3.    Typical Components of Selected Treatment
        Technologies	..    0-10
0-4.    Annualized Costs of Typical Treatment
        Components for Four Plant Sizes	    D-li
O-5.    Typical Water Supply system Costs	    0-13
D-6.    Component Costs as Percentage of Total
        Water Supply System Costs	    D-14
                                iv

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        APPENDIX A
SUPPLEMENTAL INFORMATION:
CLASSIFICATION REVIEW AREA

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                          APPENDIX A

    SUPPLEMENTAL INFORMATION:  CLASSIFICATION REVIEW AREA
A.I       Technical  Basis for Initial  2-Mil* Radius of  the
          Classification Review Area
     The EPA  classification  system utilizes ths concept of a
Classification  Review  Area  around  a  specific facility  or
activity.     EPA   has  deterained  that  in  general   a
Classification  Review  Area  2-miles  in  radius  is  a  good
starting point  for  this  analysis.  A larger  radius may  be
appropriate  in  certain hydrogeologic  conditions  or  in
accordance with specific program practice.

     The EPA  examined three  sources  of data as the basis for
identifying 2-miles as a generally appropriate Classification
Review  Area  radius.    The  data  provided  insight into  the
length   of  the  flow  path over  which  high  degrees  of
interconnection  occur.    In  addition,  the  data  indicate
distances contaminants  could be expected to  move  in  problem
concentrations  should they  be  accidentally  introduced into
the ground-water  system.   The  three  sources  of  information
examined were as follows:

     •    A survey of existing  contaminant plumes documented
          through investigations  of spills, leaks, and dis-
          charges .

     •    A survey  of the distances to  downgradient  surface
          waters from hazardous-waste facilities.

     •    Calculations  of the  distances from  which  pumping
          wells  draw  ground water  under  different  hydro-
          geologic settings.


These sources are described below.
                             A-l

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A. 1.1	Plume  Survey
     A survey of contaminant plume geometries (i.e.,  length,
width  and  depth)  was prepared  in connection with the develop-
ment  of a stochastic  model  of  corrective action costs  at
hazardous-waste   management  facilities  (Geraghty t  Miller,
Inc.,  1984).    The  plume  survey was  updated by  Geraghty &
Miller,  Inc.,  in  1987.  The  plume survey provides generalized
information on the distances contaminants have been known to
migrate  regardless  of time,  source type,  or hydrogeologic
setting.   This  information indicated  the area that may  be
affected if contaminants  were accidentally released from the
site.

     The  data  base  for  the  survey   included  ground-water
quality   investigations,   consultant  reports,   and  other
publicly  available  literature (e.g.,   scientific  journals).
The  availability  of data  was limited by  the  confidential
nature of  many privately  funded contamination investigations
and  the relatively  small  number of off-site investigations
conducted  by  the  government prior to  the implementation  of
the Superfund program.

     The   survey   found  74   contaminant  plumes  containing
inorganic  and  organic contaminants.     Hydrocarbon  plumes
consisted   of  dissolved   and  liquid  phase  (undissolved)
materials.   The sources of the plumes were spills/ leaks, and
discharges from  diverse  sources  including  municipal  and
industrial sites,   transportation   accidents,  and  unknown
sources.    Plume  boundaries  were  generally defined  as  a
detectable increase above background quality.

     The survey  showed that the median plume length was 1700
feet.   Ninety-five  per cent  of  the  plumes were  less than
miles in length.  A histogram  of plume  lengths is provided in
Figure A-l.

     The  data  were  too  limited  to  determine whether  the
plumes  in  this  survey had  reached their  maximum  lengths.
Theoretically,  if a  contamination  source  is  continuous and
the contaminant  is not degraded,  transformed, or immobilized
in route,  the plume  length will eventually  be  equal to the
distance to  •  dovngradient  discharge  point.   other factors
that   could   prevent  plumes  froa  reaching  their  natural
discharge)  points  include  insufficient  time since the contam-
inant  release,   and  the  implementation  of  an  effective
remedial program.  In some cases a steady-state condition may
be  reached  between  contaminant  input  by  the   source  and
dilution due  to recharge.   Although it is not known whether
the plumes in this survey had reached  equilibrium, it  is not
likely  that  any  one  of  the  above  factors had  any
       of  influence  on  the results.

                             A-2

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                                                     figure  A-l
I
Ul
                            00*0.9   IO-L9   2.0-£9  36-34  4.0-49  5.0-3.9  tO-03 TO-T9  AO-6.9 9.0-9.9  10.0-109  >ILO
                                                PLUME  LENGHMh Ihowor* «f fM,)

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A. 1.2      Distance  to  Downqradient Surface-Watera Survey


     ICF,  Incorporated,  conducted a survey of 117 hazardous-
waste management  facilities  for development of the EPA Liner/
Location  Model  (USEPA,   1985).    For each  site,  the  down-
gradient  distance  to  surface waters  (e.g.,  lakes,  streams,
ocean,  bay,  or marsh) was  calculated providing insight into
the distance at which  a  flow boundary for the shallow ground-
water system  is  likely to be encountered,  thus, limiting the
area potentially  impacted by a facility.

     Some  of  the facilities in  the  survey were  included  in
EPA's site visit  facility survey.  Other sites were selected
from among available Part B Permits.   A site was included in
the  survey only  if it  provided information  sufficient  to
operate  the  liner/location   model  (e.g.,  comprehensive
facility  design  parameters  and  hydrogeologic  information).
Facility  sites  were   located   on  U.S. Geological  Survey
topographic maps using latitude and longitude data.  Geraghty
& Millar assisted ZCF by  identifying the general direction of
ground-water flow from the site  on the topographic map.  The
frequency distribution histogram  for distance to downgradient
surface waters  is shown  on  Figure  A-2.   Ninety-five percent
of these distances  are less  than  2 miles.
A. 1.3	Pumping Well Capture Zones Survey	


     One of  the  criteria for establishing the typical radius
of the Classification Review Area was to identify the zone of
influence supplying  water to the pumping well.   In examining
the   relationship   between   a  2-mile   radius  and   the
identification  of water-supply wells  capturing water  from
under  a  site, a  formula (Todd, 1976) was  used to determine
the  generalized  dimensions  of  well-capture   zones  under
different hydrogeologic  conditions.  The formula, illustrated
in  Figure   A-3,  provides  a  calculation  of  the  maximum
downgradient  extent  of well  capture  (XL)  and  the  lateral
distance) (YL) (perpendicular to nonpumping, ground-water flow
gradient*).   Lateral and downgradient capture distances were
calculate*  for a range of  transmissivities  and water-table
gradient* under  pumping condition* of 0.5 to 3.0 millions of
gallons  per day  (mgd).    Incompatible  well  yields  and
transmissivities vere not used.  The governing equations and
the results  of the  calculations are shown in Table A-l.  The
well yields  were selected  to represent the  common range of
pumping  rates for water-supply wells.   With the exceptions
noted below/ water-supply wells are generally smaller than  2
mgd.  The largest»lateral capture distance  for a  2 mgd supply
well  for  the  transmissivities  and  gradients  examined  is

                             A-4

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                                                              FIGURE  A-2
                                               OOWNCRADIENT DISTANCI TO SURFACE WATER
                                                         (SOUHCEi  EPA.  1985)
IN
       IS
        K>
               II
                                                                         TOTAL till SITCS
                                                                            0.5 • 1700 It
                                                                           0.93.10,00011.
                                                                            mot • 20,000 ft.
1000    2000    3000   4000    9000    6000    7000    6000    9000
                                             DISTANCE (Ft)
                                                                                                12000   14000   MOOO    1(000   20000

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                                 FIGURE A-3

                         WELL CAPTURE ZONE (Todd, 1976)
                                      REGIONAL FLOW LINE
     WATER-TABLE CONTOURS
r
  DOWNGRAOIENT
  CAPTURE DISTANCE
                                        LATERAL
                                        CAPTURE DISTANCE

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                               TABLE A-l.
           LATERAL AND DOWNGRADIENT WELL CAPTURE DISTANCE (infect)
                           (after Todd, 1976)
                       Transmissivity/Gradient  (ft/mi)
                       10,000/30-50     50,000/10-30     100,000/5-10
  0.5 MGD  Lateral        4400-2640
          Dovngradiant   1400-840
  2640-880
   840-280
                                                         2640-1320
                                                          840-420
1.0 MGD  Lateral          N.A.
         Dovngradient     N.A.
                                          5280-1760
                                          1680-560
                  528C-2640
                  1680-840
2.0 MGD  Lateral          N.A.
         Dovngradient     N.A.
                                        10,560-3520
                                           3360-1120
                10,560-5280
                  3360-1680
 3.0 MGD  Lateral          N.A.
          Dovngradient     N.A.
15,840-5280
  5040-1680
                                                       15,840-7920
                                                         5040-2520
Governing Equations

Lateral Distance         YL • Q/2T1
Dovngradient Distance    XL - Q/2Tf Ti

YL  - ft
XL  - ft
Q   • flov rate
T   - transmissivity
i   - Hydraulic Gradient
N.A. - Not applicable.
                                  A-7

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 miles.   Thus, the  2-mil* radius would identify the majority
 of individual water-supply wells that could be drawing water
 from under a  proposed facility or  site  in directions other
 than the downgradient direction.

      NOTE:    Sxceptions  include the basalt aquifers  of the
      Columbia Plateau and Hawaii, where common well sizes are
      up to 4  mgd  and SOB* may exceed IB  cgd;  the Florida
      aquifer  in Florida  and  Georgia where common yields are
      up to  7  mgd and may exceed 8 mgd; and  the Chicot aquifer
      of the Lake Charles  Formation  in Louisiana where common
      yields  up  to 3.5  agd  are  found.    Other regionally
      extensive high-yielding aquifers where wells may exceed
      2  mgd include  the Texas Edwards aquifer,  thick members
      of the Atlantic  and Gulf  Coastal  Plains,  alluvium and
      older  sedimentary  basins in California and the 'Sparta
      Sands  in Arkansas.

      In summary, the plume survey and survey of distances to
 discharge   boundaries  support  the  2-mile  typical  radius
 concept.    The plume  data  indicate  the  distance  that
 contaminants  are known to migrate in problem concentrations,
 and  the  distance   to discharge  points  data  indicate  the
 likelihood  that  a flow boundary will be intercepted.  Pumping
 well  capture  distances  provide  the  basis  for  including
 lateral  and upgradient  areas in the review area.   Thus,  2-
 miles  is  a  reasonable  distance  to  use  for  initially
 identifying potentially  highly  interconnected  ground waters
 related to  a site under classification.
A. 2    Determining  Expanded Review Area  Dimensions for Non-
       Dare ian Settings
     This  appendix  provides  guidance  for determining  the
dimensions  of the expanded  review area.   In  general,  the
dimensions  of  the)  expanded  review  area  are   governed  by
hydrogeologic  conditions,  particularly ground-water  flow-
system boundaries, flow directions,  and  flow velocities.  The
cases betlov illustrate various conditions and  suggest methods
for arriving  at  appropriate expanded  review area dimensions.

     For  non-Darcian  flow settings,  the  dimensions  of the
expanded review area can generally be  based on the boundaries
of  the  ground-water  basin.     A basin includes  all  areas
extending  from flow  divides  at the  boundaries of recharge
areas to  the  major perennial  stream where  discharge occurs.
When the  information base is too  small  to  fully define these
boundaries,  the   classifier  can  use  the  distance to  the

                             A-a

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           LATERAL AND OOWNGRA
                            (af
                        Transm:
                        10,000,

  0.5 MGD  Lateral        4400-
           Dovngradiant   1400-
  1.0 MGD  Lateral
           Dovngradient
  2.0  MGD   Lateral
           Dovngradient
  3.0 MGD  Lateral           N.A
          Dovngradient      N.A
Governing Equations

Lateral Distance
Dovngradient Distance

YL  - ft
XL  - ft
Q   - flov rate
T   - transaissivity
i   - Hydraulic Gradient
N.A. - Not applicable,

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 nearest downgradient,  perennial stream/  where  ground water
 from the activity  area is likely to discharge, to establish
 the expanded review-area dimension.

 Karat Setting^

      In karat  hydrogeologic settings,  the boundaries  of a
 ground-water basin may vary considerably  depending on water-
 level stage in the  cave-stream  complex.  A hypothetical karst
 terrain,  characterized by  sinkholes,  sparsity  of  surface
 streams and  an  integrated  system  of  subsurface  drainage
 conduits  within  a  carbonate  bedrock  complex  is shown on
 Figure A-4.  Directly west of the activity, streams drain an
 upland area, flowing eastward to the sinkhole plain,   on the
 plain,  the  streams intersect sinkholes, and surface water is
 diverted  to the  underground  network  of  solution  conduits
 within the  karst bedrock.   This zone where surface water is
 rerouted  to the subsurface represents the  termination of the
 eastwardly  extent of the  more  resistant sandstone formation
 overlying  limestone  and dolomites.   Without  the resistant
 sandstone,  surface water has reworked  the carbonate bedrock
 into  a network of  vertical  and horizontal solution cavities
 and conduits that  drain the sinkhole plain  eastward  to the
 Little  Blue  River.   A  cross-section  of  this hypothetical
 terrain is  shown  on Figure A-5.

      In a  karst  terrain,  ground-water  circulation  occurs
 through a  system of  conduits having a variety of shape* and
 capacities.    The ground-water  flow system  undergoes major
 changes depending  upon  the  magnitude  of  a  precipitation
 recharge  event.   For  example,  in  the  hypothetical  example
 during  periods  of lov flow  (little or  no precipitation),
 surface, water recharges the carbonate aquifer at the sinkhole
 plain and  travels  through  a series  of  solution cavities to
 the ground-water  Basin B  trunk  conduit   (Figure A-6 [A]).
 Under these conditions,  each ground-water  basin hydraulically
 operates as a separate  entity.   The  general direction of  flow
 in  Basin B  (although  tortuous) is toward the  Little  Blue
 River.

      As shown in Figure A-6 (B), recharge  to the aquifer via
 sinkholes  and  swallets  during   peak  rainfall  events,  causes
 ground-water levels  within  the Basin  B  trunk  conduit to
 increase, to the point where upper cavity  transverse conduits
 are Intersected  and ground  water  migrates  into the trunk
 conduit* of Basins A and C.  This process is termed ground-
 water piracy.  During high-intensity recharge events, ground
 water  from  Basin  B,  which  could  potentially  contain
 contaminants from  the   activity,  will  travel  to all three
 ground-water basins.

     Xarst  basins  can  be  mapped using  dye-tracing studies
 field  mapping, spelunking,  geochemical  reconnaissance,  and
water-level  maps.    However,   due   to  the expense  of   such

                             A-9

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                             FIGURE A-4

       HYPOTHETICAL KARST TERRAIN WITH 2-MILE REVIEW  AREA
  EXPLANATION
   •    PROPOSED
 	CLASSIFICATION REVIEW AREA BOUNDARY
   o~   SPRING/SEEP
 —v—-  FLOW ROUTE
-*	H^M-IXVEL OUTFLOW ROUTE
——  OHdOND-YttTCT BASIN SOONOARY
 ^^-•  SWttUET OF SINKING STREAM
                                A-10

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                                  FIGURE A-5

             GENERALIZED CROSS SECTION OF A KARST HYDROGEOLOGIC SETTING
   WEST
SANOSTO
                             FACIUTY
                                                                LITTLE BLUE
                                                                   RIVER
                                                            GROUND-WATER
                                                            FLOW CONDUITS
          •"n-"-i
EAST

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                      FIGURE A-6


  EXAMPLE OF OVERFLOW ACROSS  GROUND-WATER BASINS
  80-



  60-



  40-



  20-



  0-



 -2O-



-40-
ta
         BASH C
BASH B
SAStN A
                    BASE FLOW CONOmONS

                              (A)
80
6O-



40-



2O-
       SAStN C
                          BASIN B
                       FLOW ORECTONS
                    BASIN A
                                                ECOLOGKALUr
                                                VITAC AREA
              HIGH INTEf^SJTY H-GW
                           (B)
                        A-12

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 studies,  few basins have been mapped.   As a surrogate, it is
 recommended that the  distance to  the  nearest downgradient,
 perennial   streaa  be   eaployed  to  establish  the  expanded
 review-area   dimensions   as  illustrated  in  Figure  A-7.
 Generally,  the appropriate perennial stream segment will be
 spring fed  (i.e.,   cave-stream  discharge  springs)   and  not
 subject to  disappearance into cave-stream flow  (i.e., sinking
 stream).

      The  classifier is cautioned  that  the nearest perennial
 stream may  not  be  downgradient  and,  therefore,  not  the
 discharge point for the subject ground-water basin.   Such an
 error can be minimized by locating the topographic high  (the
 water-shed  divide)  between the nearest perennial streaa and
 adjacent streams.   The correct perennial streaa to employ in
 this  suggested methodology is generally  on  the saae side of
 the topographic high as the activity.   The ground-water basin
 of  interest will generally be discharging  to the perennial
 stream on  the  same   side  of the topographic  high  as  the
 activity/facility.   In rare  cases, the activity or facility
 is  located  in  the  vicinity of the topographic high between
 perennial streaas.   In such a case, the expanded review area
 should extend  to the nearest  perennial  streaa on all sides of
 the  topographic high,  unless site-specific  data concerning
 ground-water flow direction are available.

 Other settings

      The  expansion  of  review area dimensions  for fractured
 rock  and extrusive  igneous (basaltic lava) settings can also
 be based on ground-water basin boundaries.  In these types of
 settings, there is  a  strong  potsntial  for  flow  to  be pref-
 erentially  channeled  through  fracture  zones  at high veloci-
 ties.    Bedrock  fractures  are  often  expressed in  surface
 features, such ass streaas  and other surface depressions, and
 can often be  identified through aerial  photography and other
 forms  of fracture  trace  analysis.   The identification of
 thess  fracture zones  can  be  very useful in  predicting the
direction  and  extent  of   non-Darcian,  high-velocity  flow.
This  information  can  then  be  employed to  establish  the
expanded review-area  dimensions.   A hypothetical example is
shown in Figure A-8.  Similar to its use in the evaluation of
karst  settings,  topography can be utilized  to help identify
the likaly  discharge  points  for ground watsr  originating at
the facility.
                             A-13

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                           FIGURE A-7
     HYPOTHETICAL KARST TERRAIN WITH EXPANDED REVIEW AREA
 EXPLANATION
  •    PROPOSED FACILITY
	CLASSIFICATION REVIEW AREA BOUNDARY
•: *•;•: I  EXPANDED CLASSIFICATION REVIEW AREA
  •    3MMG HOUSE FOR DOMESTIC USE
  »-   90UNO/SEEP
       ROADWAY
                             A-14

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                            A-8
HYPOTHETICAL  EXAMPLE OF REVIEW-AREA EXPANSION
          IN A FRACTURED Rrvv ctWT»~  PANSION
FRACTURED ROCK SETTING
        EXPLANATION



  [||i|  UMNOCO KVICW ANCA



  Hj  FACO.ITY ACTIVITY



  V   OSTAMCC TO NCAUCST B<«CHA«Oe POINT
                    A-15

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 A.3      Subdividing the Classification Review Area
A.3.1    Identifying   Ground-WaterUnits  and   Analyzing
	I n t a rconnect ion	


     Subdivision of the ground-water regime .into ground-water
unite  generally  involves  collacting  and avaluating informa-
tion related  to geology, hydrology, and  management  of ground-
water  resources  (controls on withdrawals/recharge, properly
abandoning deep wells,  etc.).  The description of the ground-
water  regime  and  any  potential  subdivisions  should  be as
quantitative  as  possible.   The  Agency recognizes that the
degree  of  accuracy with which the Classification Review Area
can be  subdivided is limited by the abundance and  quality of
available  data.   Supplementing  the existing data  base with
field and laboratory investigations both on-site and off-site
nay be needed to accurately confirm the  existence of subdivi-
sions.   The  following  discussion will  serve  to  guide the
types  of  data  needed  to  justify  the  subdivision of  the
Classification  Review Area.

     Background   information  on  geologic  formations  and
occurrence/movement of  ground  water  can be  obtained  at  a
regional scale  of accuracy  from State and Federal agencies.
Topographic maps published by the U.S. Geological Survey are
now available at useful  scales for most  of the nation.  These
can  help  identify  ground-water  flow  directions  and  flow
divides  for the uppermost aquifer.   Data on the distribution
and  characteristics  of soils  are available  from the U.S.
Department of Agriculture  Soil Conservation Service.  General
information on precipitation, run-off, and recharge rates can
be  obtained   from  the  U.S.  Geological  Service  and can  be
supplemented  by  climatic  data  from weather  stations around
the country.    Ground-water pumpage and locations/depths of
wells  can  generally be  obtained from  State agencies that
issue well permits or  from local  public-health  agencies and
water districts.

     Thev first  step is to identify  all  aquifers occurring
within the ground-water regime of  the Classification Review
Area.   In  areas that have  been well-studied, these will be
recognized and  documented in government agency  reports.   In
poorly studied  areas, proper recognition  of  aquifers can be
inferred from litholbgic descriptions  of geologic formations,
structural features of  the area  (if  flov  is mainly through
fractured rock),  and  the  depth  and  design  of  wells.   The
areal and vertical extent  of hydrogeologic  units within the
ground-water  regime can be shown in  a  series  of  cross-aec-

                             A-16

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 tions and saps.   For  most  hydrogeologic  settings,  it  will  be
 moat useful to interpolate between location* where conditions
 are  known  (i.e.,  walla,  outcrops,   excavations,  etc.) and
 present variationa  in thicknaaa and  elevations  of important
 unita with contour maps prepared at a common scale.

      Aftar the. identification and graphical representation  of
 the geologic  framework,  it  is  possible  to  identify  ground-
 water units within the ground-water regime using the guidance
 provided in subsequent sections.

 Type 1 Boundaries?  Ground-Water Flow Divides

      The concepts  of  ground-water  flow  systems  may  not  be
 faailiar to  some  readers  and,  therefore,  may need  to  b«
 reviewed so  that the  reader can understand  the concept  of
 flow-divide  boundaries between ground-water units.   Figure  A-
 9  shows  in  vertical  cross  section  a  series  of  adjacent,
 shallow, ground-water  flow  systems  for a  single-layer, water-
 table  aquifer.   The  systems are bounded  at the  base  by a
 physical   impermeable  boundary.    As  is  typical  in  humid
 regions, the water-table profile conforms  to the topographic
 profile.

     The  flow net in  Figure  A-9 (a)   shows that  ground-water
 flow occurs from  the  recharge area  in the highlands to the
 discharge  areas  in  the lowlands  (i.e.,  valleys).  Vertical
 line segments  AB  and  CD beneath  the  valleys  and  ridges
 constitute  ground-water  flow divides,  i.e.,  imaginary im-
 permeable  boundaries across which there  is no flow.  In the
 figure,  these  grou 1-water  flow divides  separate adjacent
 flow systems ABCD  and ABFE which, for purposes of subdivi-
 sion,  correspond to ground-water units  separated by  Type i
 boundaries.

     In  simplified, symmetrical  systems,  such  as those il-
 lustrated  in Figure A-9 (a),  ground-water  flow divides  coin-
 cide exactly with surface-water divides and extend vertically
 to the base  of the aquifer.  In more  complex topographic and
 hydrogeologic settings, these properties  may diverge substan-
 tially from the situation illustrated.

     A ecsjparison of Figures  A-9  (a)  and  (b)  reveals how flow
 pattern* and divides are altered when the  undulations in the
 water  table  are superimposed   on   the   regional  hydraulic
 gradient towards  a more regional stream  and discharge  area.
 Ground-water  flow divides  in Figure  A»9 (b) extend  through
 the  full  thickness of the  aquifer  only at either end of the
 entire flow regime.   The full dimension of the  flow regime
may  or may  not  be  encompassed  by  the. 2-mile  radius.   The
total length,  S,  in the  figures, can range from hundreds  to
thousands of feet.

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                               FIGURE A-9



           HYDROGEOLOGIC SECTIONS SHOWING FLOW SYSTEMS  OP

            INCREASING COMPLEXITY WITH TYPE 1 BOUNDARIES
                     TYPE I BOUNDARIES
 0.2 S
       OUCHANM TO
       MMIOMAI. STMCAM
       AMO WITLANDS
                                                                   —TYPE I

                                                                    BOUNDARY
         01S   0.2 S   03S  04 S   05S   0.65  07S  08S   0.9S
0.2 S
                                                                   —TYPE I

                                                                    BOUNDARY
         OIS   025   03S   0.4S   05S   0.65  0.7S   0-8S  0.9S
                                  A-18

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      Figure  A-9  (c)  is an example of more complex conditions
 in which the flow patterns  and flow systeas are affected by
 both  topography  and  regional .variations in hydraulic conduc-
 tivity  of layered earth materials.   Given adequate data, com-
 puterized models of  real sites can  provide approximations of
 ground-water flow patterns.   In general, the level of sophis-
 tication employed to  demonstrate the  presence of  a  Type 1
 boundary should  be  commensurate  with  the  complexity  of the
 hydrogeologic setting.

      The spatial location of the water-table and ground-water
 flow  divides may be  stable under natural flow conditions but
 can be  modified by man-made  hydraulic  stresses,  such  as
 large-scale  ground-water withdrawals  or recharge.   In some
 case* it will be necessary to estimate the permanence  (i.e.,
 location with time)  and position of  ground-water flow divides
 under  stressed  conditions   from  available  hydrologic  and
 geologic data and foreseeable changes in water use.

      A  good  example  of ground-water  units separated  by a Type
 1  flow  divide boundary is  shown in Figure A-10,  The setting
 illustrated  consists of  two alluvial valleys with high-yield
 wells completed  in  sand and gravel deposits,  separated by
 sandstone bedrock that can  only provide  limited supplies to
 domestic wells.  Ground water in the alluvium is derived from
 precipitation and from  the bedrock and  discharges  to the
 river under  natural  conditions.   Under  pumping conditions,
 the water pumped by  the high-yield  wells is derived largely
 from  the  river,  from  local  precipitation,   and  from  the
 bedrock.  Near the  wells in the  western valley, flow-system
 boundaries are affected by  ground-water  withdrawals and are
 stable  as  long  as  the well  discharges  are  steady.    The
 ground-water  flow divide separating the  two valley aquifers
 is  not   affected by  pumpage,  and  provides  the   essential
 characteristic that  allows  the delineation  of ground-water
 units A and B.

 Flow Analysis.  In order to provide  a defensible ground-water
 flow-divide delineation,  a limited flow analysis is generally
 necessary.    An  acceptable  approach is  to prepare a  water
budget   for   the  ground-water  unit  in  order  to  show  a
 reasonable* order-of-aagnitude balance on flow into and out of
the system.   This water  budget could involve the preparation
of a  ground-water flow net  (see Glossary for definition) for
the uppermost aquifer  with  accompanying estimates of volume-
 tric flow into and out of the unit.  The flow net can be gen-
 eralized and need not be rigorously  correct in a quantitative
 sense.'   The  analysis should  be carried out even though part
 of  the   ground-water system continues  outside the Classi-
 fication Review  Area,  that  is, if  part  or all of  the dis-
charge  or recharge  area  of the  unit  extends  beyond  the
Classification Review Area.
                             A-19

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                                     FIGURE A-10
                     EXAMPLE OF TYPE 1  FLOW DIVIDE BOUNDARY
                                                        ^
                                 GEOLOGIC MAP
                                                                          2 MILES
                                HYDROGEOLOGIC CROSS SECTION
                                      GftOtMHMTCR FLOW DIVIDE
       A(WtSt)
40OFT
ZOO FT
ALLUVIAL AQUFER
SANDSTONE  AQUIFER
GENERAL FLOW DRECTION
                                               Acrnvc
                                             MUNICIPAL
                                            SUPPLY WELL
         '/'/ '   BASE OF ORCULATION
                                                  !   CLASSIFICATION  REVIEW

                                                     AREA BOUNDARY
                                        A-20

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      The semiquantitative  flow  net of the,,uppermost  aquifer
 should  be  supplemented  by  a  vertical  hydrogeologic  cross
 section  and  supporting  data  shoving  that  the   uppermost
 aquifer is,  in  fact,  underlain by an extensive aquitard or
 crystalline rock non-aquifer within the Classification Review
 Area.    The flow net  can be  based on  available water-table
 elevation data,  as interpreted  from water  levels  in  rela-
 tively shallow wells, as  well as  on  locations/elevations of
 springs, wetlands,  and  perennial  streams,  and supplemented
 with topographic  elevations.    The rates  and  directions of
 flow  can  be  estimated  in  plan   view  given  a water-table
 contour map and estimates of  aquifer  thickness  and  hydraulic
 conductivity.    The  conductivity   can  be obtained  from the
 area-specific reports,  field or  laboratory  tests,   or by
 estimating  a  range  from the  scientific  literature  based on
 earth  material type.  Flow patterns inferred from these  data
 must  also   consider  significant  spatial  and directional
 variations  in conductivity   in  areas  having   more  complex
 stratlgraphie  and structural  geologic  conditions.

     At the beginning of the  flow analysis,  it is  important
 to  determine  whether  the ground-water  flow  system is in a
 state  of steady or  transient flow.   Areas that are  charac-
 terized by  a lack of  ground-water development  and usage can
 generally  be  assumed to  be  in  steady state.   This will
 simplify the  analysis  because  the estimate  of system dis-
 charge  can  be equated to  recharge.  If the natural recharge
 rate compares  favorably  with a reasonable percentage  of mean
 annual  precipitation,  the  ground-water flow divides  can be
 considered  reliable.   The applicant  can go to the  ground-
 water  literature  to obtain  reasonable estimates to recharge
 in  any geographic/ground-water  region of  the  United   States
 (e.g.,  see USGS Water-Supply Paper  4 by R.C. Heath,  1984).

     In areas characterized  by large-scale  withdrawals of
 ground  water  from shallow or  deep aquifers,  the flow regime
 is  more prone to  be  in  a  transient  state.    Evidence of
 transient conditions are as follows:

     e  Declining ground-water  levels.
     e  Depletion of ground-water storage.
     e  Movement of flow divides.


When suafc evidence  of transient conditions exists, it may be
necessary to  estimate the  ultimate steady-state position of
the  flow divides  assuming  conservatively large withdrawal
rates and saall water-flow and storage properties.

Type 2  Boundaries;  Low-Permeability Geologic Units

     The  Agency  would  generally  assign  a  low degree of
interconnection  across  the  low-permeability  geologic  unit
 (Type  boundary)  if the following conditions can be  shown:

                             A-21

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     • The   low-permeability   geologic   unit  is  laterally
       continuous  beneath the entire area "and/or limits  the
       lateral  continuity  of-  the  more  permeable  geologic
       unit.

     e There  are  no known wells, mine shaft*,  etc.  that  are
       improperly  abandoned  or  unsealed  through the geologic
       unit.

     • The geologic unit has a small permeability relative to
       both adjacent  geologic units  and  to geologic media in
       general.

     • The  flow of water through the geologic  unit per unit
       area  is insignificant relative to the  flow  of water
       pc~ unit area  through adjacent strata.


     Low-permeability geologic  units  include  fine-grained
sediments and sedimentary rocks, such as clays and shales, as
well as  crystalline igneous and metamorphic  rocks that have
few interconnecting  fractures.   Because  these materials have
small  permeabilities,  small quantities  of water  will  be
transmitted through  them  in response to hydraulic gradients.
Such  favorable head  relationships   further  ensure  that  the
direction of  ground-water movement  at the boundary serves to
inhibit  the  migration of contaminants into  and  across this
type of boundary into the adjacent ground-water unit.

     In selected  environments,  such  as deep geologic basins,
it  may  be possible  to  show  that  the  flow  of fluids  is
negligibly  small  through the  low-permeability  unit.   The
actual cut-off values of  key variables such as permeability,
thickness, and hydraulic  gradient are not specified in these
Guidelines and are left to professional judgments.

     A  setting where the  presence  of  a thick,  regionally
extensive   aquitard  establishes  a   low   degree   of
interconnection  between  a  shallow  ground-water  unit  and  a
deeper underlying ground-water  unit  (aquifer)  is  shown in
Figure A-ll.   This  configuration is common  in the Atlantic
and Gulf  coastal  plain settings where the  lower aquifer is
the  principal  regional  aquifer and is  a  source  of water
supply.   It  is overlain  by  an  extensive confining clay that
may be tan* of feet thick.   The shallow ground-water aquifer
system supplies only limited amounts of  water to wells.  The
reasons for the low interconnection  between aquifers in this
setting* are as follows:

     • The flow of water  through the aquitard is exceedingly
       small.

     • Water  travel time through the aquitard is very great.


                             A-22

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                                   FIGURE A-ll



                          EXAMPLE OF  TYPE 2  BOUNDARY
                               CLASSIFICATION  REVIEW AREA




                            2-MILES              	2-MILES
MSL
    10
                     ALLUVIAL AQUIFER

                     (UPPER GROUND-WATER

                     UNIT}
                                       FACILITY
   SO
                                        AQUI7ARO
85
o
   4O
  6O
                                     AOOFER

                             (LOWER GROUND-WATER UNIT)
  TO  *-
                                       A-23

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      In general,  the demonstration  of  the  existence of a Type
 boundary   requires  that  the  laterally "continuous,  low-
 permeability non-aquifer  that conotitutee  the  boundary  be
 identified and characterized.  The following factors should
 be considered in  making this  demonstration:


      e stratigraphic setting  a.iJ lithologic characteristics.

      e Structural  setting  and joint/fracture/fault  charac-
        teristics.

      • Hydrogeologic setting  and  hydraulic  head/fluid flow
        characteristics.


      The first  distinction should be between whether the non-
 aquifer is of sedimentary or igneous/metamorphic origin.  If
 it is sedimentary in origin,  an identification of the envir-
 onment of  deposition will permit  inferences about  the ex-
 pected  geometry,  thickness,   and  continuity of individual
 strata.    These  inferences  should be  defended with geologic
 sections  including  data  from  well  logs  and/or  measured
 sections.   The age of the unit, the  degree of  cementation,
 and degree  of  compaction are  all  qualitatively related  to
 water-bearing  characteristics  (hydraulic conductivity  and
 porosity).

      If the  unit  is an  igneous  or  metamorphic  rock,  the
 continuity and thickness can usually be  inferred from geo-
 logic maps and reports for the region in which the Classifi-
 cation Review Area exists.    Identification  of igneous rocks
 that  have  tabular geometries  such as volcanic  flows, ash-fall
 deposits,  or intrusive sills  and dikes will allow inferences
 about thickness and continuity.   These may serve as aquifers
 or  aquitards  within  a   sequence  of  sedimentary  rocks.
 Crystalline basement rocks  of igneous and metamorphic origin
 underlie the  entire North American continent.  In areas where
 these rocks are  fractured  and exposed  at or near  the land
 surface,  they  generally  serve  as poor-yielding  aquifers.
However,   significant  circulation   can  be  assumed  to  be
 restricted  to  the  upper   few  hundred  feet   because  the
 fracture* tend to close with depth.   In  other areas, where
these recks) are buried by younger  rocks,  they can generally
be assuaset to represent the base of active circulation unless
there i» evidence to the contrary.   In these situations the
Type  2 boundary  is  equivalent  to the bottom  of the ground-
water regime  (see Glossary).

      A general  knowledge of  the tectonic  setting and struc-
tural  geologic history  of  the region will  provide insight
into  the types and  frequency of  geologic structures  to  be
found in  the classification Review  Area.    Numerous field
studies  have  shown  that  significant  ground-water  flow  in

                            A-24

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 consolidated sedimentary and crystalline rocks  is  controlled
 by  geologic  structures.     These  feature's  include   folds,
 faults,  and associated joints- and fractures in the  rock.

      Major  structures  such  as  fault zones  that  intersect
 consolidated   rock  formations  may  hydraulically  connect
 multiple aquifers into a system of aquifers.   Fault zones in
 consolidated rocks  are known to  collect  water  from  large
 areas and control the locations of ground-water discharge at
 major springs.    in  uneonsolidated   n«dimento  and  in soae
 structural settings,  fault  zones  can have the  opposite effect
 by producing barriers to flow.   Individual joints  and  small
 fractures in consolidated  rocks  and  sediment can be  mapped
 systematically  with  field  studies;  however,  proof of  their
 absence  is  the  more important element  in demonstrating the
 presence of a Type   boundary.

      The  best  evidence  of  low-permeability,  non-aquifer
 conditions  constituting a Type  boundary are those  related to
 the  hydrogeologic setting  and measured hydraulic parameters.
 The  hydraulic  conductivity of  both  sedimentary deposits and
 igneous/metamorphic  rocks  can be  estimated  within  several
 orders-of-magnitude  on the  basis  of lithology alone as  shown
 in Table A-2.   In parts of the United States associated with
 large ground-water usage, there has been a  need  to  understand
 the ground-water  regime, and these areas often will  have been
 studied  by various  government agencies.   Consequently, the
 hydraulic properties  of  aquifers  and aquitards will be known
 in quantitative terns.  In these areas the  thickness,  lateral
 extent,  and hydraulic  conductivity will  be documented.   A
 favorable  condition  would  then  be associated  with a recog-
 nized aquitard  or aquiclude  that is known to be  relatively
 thick, homogeneous,  widespread,  and  poorly permeable.   The
 optimum head condition would  be such that  vertical hydraulic
 gradients are directed upward through the  unit, i.e., across
 the Type  boundary.

Type ? Boundarj.es;  Freshwater/Saline Water Contacts

     Type  3  boundaries between  bodies of  ground  water with
contrasting TDS concentrations most commonly occur within the
 following types of hydrogeologic settings:

     • ar»e-water  intrusion  into  fresh-water  aquifers  in
       coastal regions.

     •Saline waters associated  with  ancient  evaporite de-
       posits in sedimentary basins.

     • Saline  waters  associated  with  closed  topographic
       basins in arid regions.
                             A-2 5

-------
                         TABLE A-2

RANGE OF VALUES  OF HYDRAULIC CONDUCTIVITY^AND PERMEABILITY
              (AFTER FREEZE AND CHERRY, 1979)
Rocks ^nconsol'dof«d K K K K
^ deposits (f MJov) (cm/s) (m/s) (adi/Ae*




\ \
1 |
O "5 T
S £
I
-
1
"3
o
0
„
S 2 o
S « i *
-ST, g
Z o c ,/• .22
SS2ts **•
C5 =S §
Q. S .y- **
c |5 3^
"° ° ° j,*?
•2fJ'|c gl
o£S— — ~~-
^ J'l 1
J 0
CO _
J 1
j «52
i!s if
32 ° i
Ilfl 1
511*?
1*1
1
;

to6
•IO s
!%/

-IO4
-IO 3
-JO2

-10

• f





-10-'

-io-2


- to-3
LtO'4
f
•

•
• 1O"5

to2

-to

-1
• to"
-to-2

- tO"3

-to-4
-to-5

-to-6


-to-7
•to'8
•10'9

•10- l«r*
L1o-7 L,0-»
pi
HO6
-10"

-to-2
-to-3
-to-4

-to-5

-io-6
1C'7

tO'a


to-9
IO"0
to-11

to"2
IO"3



-to5
-to4
-to3
M
•to2
m, ^^^
1 \J
• 1
-1
'irr*
JO

J^^ *
J^J
to-3
to-4
_
to"3

io-7
                           A-26

-------
      • Saline  brines  in deep geologic basins.
                                          •*
      • Geothermal  fluids  in tectonically active regions.
      In  the above  settings,  the IDS  of naturally occurring
 saline  water nay  be 3 to  10 times greater  than the 10,000
 mg/L  criterion.   Owing to natural concentration gradients, a
 zone  of  diffusion is normally  observable  between the saline
 and  fresh  ground waters.    The 10,000  mg/L  TDS isometric
 surface  will  generally be situated within the diffusion zone
 separating  the waters of contrasting salinities.

     Figure A-12  illustrates how a  wedge of  sea water that
 has  intruded  into an  unconfined aquifer is  identified  as a
 separate  ground-water unit  of  higher salinity  and density
 relative  to  an  adjacent  ground-water  unit,  in the  same
 aquifer,  that  contains fresh water.   In this setting, there
 exists  a zone  of diffusion  between  two flow  systems  that
 contain  fresh water and  sea water.   The  type  3  salinity
 boundary  would occur  along  the 10,000  mg/L  TDS isometric
 surface.

     A  second hydrogeologic  setting  characterized  by  the
 presence of near-surface  evaporite  deposits  overlying deeper
 bedrock units  is  shown in Figure A-13.   Salts are dissolved
 from the  evaporite  units  by the circulating ground waters,
 and  a shallow  zone  of saline  waters  coexists  with  fresh
 ground waters within the same flow system.  However, based on
the delineation of a Type  3  boundary, two  distinct ground-
water units can be identified.

     Although the  saline  water is primarily  confined  to the
 low-permeability evaporite  formation,  this water leaks  into
 the underlying aquifer creating  a  zone of  diffusion within
the underlying  aquifer.   The boundary  between the.  two ad-
 jacent ground-water  units would be drawn  along  the  10,000
mg/L TDS  isometric surface within  the diffusion  zone.   The
diffusion zone would be a  stable feature assuming  the  flow
 system is in both hydraulic  and geochemical  steady state.
The degree  of interconnection between  these adjacent ground-
water units) is  defined  to  be  intermediate.   The  type  of
 setting illustrated  in Figure A-13  is not as common i» the
 coastal intrusion  setting illustrated  in Figure  A-l,  but it
 is known to exist in selected parts of the United States.

     In the above two  settings, the  intermediate degree of
 interconnection between  ground-water  units   is  due  to the
 limited potential  for the  exchange  of  waters across a Type 3
boundary within a  diffusion  zone.   In  the first setting, the
 salt water and fresh water are in separate, but adjacent flow
 systems.    In the  second  case,  the diffusion zone  is  more
 extensive and may  or may  not  be within a single flow system.

                            A-27

-------
                                   FIGURE A-12
                     EXAMPLE OF TYPE  3  BOUNDARY  THROUGH AN
                    UNCONFINED AQUIFER-IN A COASTAL SETTING
                        (GROUND-WATER UNIT)
                           TYPE 3
                          BOUNDARY
                                               m& SALINE WATER :8^$8W3
                                               >:::*£•:: (GROUND-WATER UNITj SW&ra&W&S
BASE OF AQUIFER

            EXPLANATION
           - a. -
>30,000mg/l TOS WATER
DIFFUSION ZONE
GROUND-WATER FLOW  DIRECTION
WATER TABLE
CLASSIFICATION REVIEW AREA
tO.OOOmf/l TOS ISOCONCENTRATION LINE
                                       A-28

-------
                                        FIGURE A-13


        EXAMPLE OF  TYPE  3 BOUNDARY IN AN EVAPORITE/SALINE WATER SETTING
                                                                         UPPER
                                                                    BEDROCK AQUIFER
                                                                (JJPPER GROUND-WATER UNIT
                                                                                 ALLUVIAL
                                                                                 AQUIFER
                                                                                            ZONE OF
                                                                                           DIFFUSION
                                                                           TYPE 3
                                                                          BOUNDARY
                                                                       10,000 MG/L IDS
EXPLANATION
EJlJilllf   HIGHLY SALINE WATER

I     J   DIFFUSION ZONE

_a_   WATER TABLE

	^   GROUND-WATER FLOW DIRECTION

 CRA    CLASSIFICATION REVIEW AREA

-------
A  third case involves a single regional flow system with the
diffusion  zona  in  tha deapar and more downgradient and of the
system.

     Tha third  aatting  include* naturally aaline ground vatar
contained  within   topographically-closed  structural  basins
within  arid  parts of  the  western United States  (e.g.,  the
Great Salt Lake Desert).   An example of such a setting wh«re
the  water  is  recharged  froa  runoff  froa  mountain  ranges
adjoining  the basin, circulates  to the center of  the basin
and  discharges  to playa lakes and the atmosphere is shown in
Figure  A-14.   These  settings are  known to have brine waters
whose  salinity  greatly exceeds  the 10,000  mg/L  Class  III
criteria within the discharge area to depths as great as 000
feet below land surface.

     Distinct ground-water units  can be  delineated based on
the  identification of Type  3 boundaries as shown in Figure A-
14.   Under  natural  conditions,  the diffusion  zones encom-
passing these boundaries are stable, and ground-water units A
and  B  can be identified  as shown.   Large-scale withdrawals
from upgradient  fresh ground  water or  injection  into  the
saline  ground  water  can   laterally  displace  the  diffusion
zone.  The pumped  wells may eventually yield saline water and
will cease  to  be  sources of drinking water.    Thus,  the
potential  to cause  adverse water-quality effects  may result
from improper resource  management.

     Type  3  boundaries are equivalent to the 10,000 mg/L TDS
isometric  surface  through  the ground-water regime.   These
boundaries can  then easily be recognized and mapped when TDS
data are available for ground waters froa various depths and
locations  in  the Classification Review Ares.  The elevations
at which ground-water TDS  is equal to or greater than 10,000
mg/L has  been  mapped and  published for  selected  basins and
regions.   The  principal sources  for such data are the U.S.
Geological Survey  and State geological surveys, especially in
states  having abundant oil and gas resources.  In areas of
known sea-water intrusion,  or upcoming of salt water due to
pumpage, published data are occasionally available that will
show in vertical section or plan view the extent of the salt-
water wedge.   This may be  conservatively taken as the 10,000
ag/L TO*  boundary  where   more specific TDS  data are  not
available.    In areas  of   known  high-temperature  geothermal
resource** published data  are available to  estimate the Type
3 boundary location.   Because  these  areas are few in number
and  are limited in areal extent,  fev will be co-located with
potential  Classification  Review Areas.   Equally limited are
data bases for  saline-water settings associated with soluble
evaporite  deposits.  At specific sites in  these  areas,  the
relationship  between  water  quality,  soluble  strata,  and
ground-water  flow  directions can be established and the Type
3  boundary mapped.   This  relationship can  be  assuimd in
adjacent areas,  where the  stratigraphy and  flow patterns are

                             A-30

-------
                      FIGURE  A-14


  EXAMPLE  OF TYPE 3  BOUNDARY THROUGH  BASIN  FILL
      IN A  CLOSED BASIN/ARID CLIMATIC  SETTING
IMPERMEABLE
CRYSTAL tNE
BEDROCK
                                      TYPE 3
                                      BOUNDARY
    EXPLANATION


    lliljliiljjjl  HIGHLY SALINE WATER


    [ ___]  DIFFUSION ZONE


    __f __  WATER TABLE


     	—  GROUND-WATER FLOW DIRECTION


     CRA   CLASSIHCATION REVIEW AREA

-------
 known,  in order to  extrapolate  the Type 3 boundary to other
 parts of the Classification Review  Area.   ^


 Tvoe 4  Boundaries?   Gradient-Based  Boundaries

      A  Classification Review Area  can  also  be subdivided on
 the  basis of ground-water flow  relationships  under certain
 specific  conditions  such   as,  if   the   region  of  the
 Classification Review Area that will always remain upgradient
 of  the  facility or activity can  be  identified  as another
 ground-water unit.   The boundary  separating  the upgradient
 and  downgradient regions is termed a  Type 4, gradient-based
 boundary.

      The demonstration  of a gradient->ased boundary must show
 that the section of  the Classification  Review Area upgradient
 from  the   facility/activity  in  question  will  not  be
 significantly  affected  by   any  releases  from  such  a
 facility/activity,  even under worst-case  conditions.   These
 conditions  would  include  the  maximum  sustainable  level  of
 hydraulic stresses associated with  waste releases and ground-
 water withdrawals  that cause the greatest change in ground-
 water flow pattern.   If it can be shown that a section of the
 Classification Review Area would still  remain far enough away
 in   an   upgradient   or  cross-gradient  position  from  the
 facility/activity to preclude  ground-water movement from the
 facility/activity to that section,  EPA  may recognize a Type 4
 boundary separating  these two sections.

     The gradient-based boundary would generally be associ-
 ated  with  a  shallow  uppermost aquifer  that has a relatively
 small water-transmitting  capacity  (i.e.,  transmissivity)  by
 virtue  of  its  low-to-noderate hydraulic conductivity and/or
 small saturated thickness.   When the transmissivity is small
 relative to the ground-water withdrawal  rate at a well field,
 a  steep  and  areally  limited  cone  of depression  develops
 around the well field.  Ground-water flow pattern alterations
would tend to be smaller and more restricted to the proximity
 of the area in  which  water is being added or withdrawn.

     Thet maximum sustainable stress scenario for a worst-case
 analysis! would  assume two conditions:


     • Ground-water   withdrawal  rates   in  the  non-affected
      . upgradient  areas  would  be at the  maximum  steady
       sustainable yield of the aquifer.

     • Leachate release rates  at the facility/activity would
       be at a  maximum  steady rate  given any excess hydraulic
       head  at the  facility/activity as well as the vertical
       hydraulic conductivity  of earth materials beneath the
       facility/activity.

                             A-32

-------
 These  stresses  and  the  resulting steady-state ground-water
 flow regime within the ground-water unit can be simulated in
 order  to   define  the  gradient-based  boundary.    Numerous
 computerized flow models are now commercially available to
 make this  simulation.  This type  of hydrologic modeling will
 involve  special skills  and professional judgment, but would
 not   necessarily  consume  more   resources  than   simulation
 modeling needed to  support identification  of Type  1  and 3
 boundaries.

     The modeling  effort would generally proceed through the
 following  steps:


     e Characterize  the  key hydraulic  parameters governing
       flow within  the  region  to be  simulated   (hydraulic
       conductivities,  thicknesses,  and  flow or hydraulic
       head conditions along boundaries  of the region).

     e Determine  the  areal  distribution  and magnitude  of
       pumpage   that  would  permanently  draw  ground-water
       levels down hear the base of the  aquifer.

     e Simulate  the  steady-state   drawdown  and ground-water
       levels (heads)  across the region  and  superimpose these
       on  the  pre-existing  potentiometric  surface  of  the
       aquifer in question.

     e Infer the ground-water flow pattern from the simulated
       worst-case potentiometric surface.

     e Identify  the  gradient-based boundary on the basis of
       flow patterns.


     The Type  4 boundary can  be  recognized as  the flowline
that delimits a set of  flowline*  terminating at  the ground-
water withdrawal point* in  the upgradient region.    An example
of such  a  limiting  flowline is illustrated in  Figure A-15.
On the upgradient side of thin flowline, all ground water is
ultimately  contained  by  maximum  sustained withdrawals  at
hypothetical valla.    on the  downgradient  side,  all ground
water continues)  flowing  around and away from the  withdrawal
area.  This ground water  eventually flows beneath or near the
facility depending on the magnitude of volumetric releases at
the facility.  Significant  releases can  cause mounding of the
water table and  a  local  reversal of ground-water movement in
an upgradient  direction.   In  the particular hypothetical
situation depicted  in Figure A-15, this hydraulic stress is
seen to  be snail relative  to  the  withdrawal stresses in the
upgradient region.


                             A-23

-------
                                  FIGURE A-15


                 *     A TYPE 4  GRADIENT-BASED BOUNDARY DEFINED
        ON THE BASIS  OF SIMULATED- GROUND-WATER FLOW PATTERNS
  NON-Aff«cttd
  Upgrodient Region
Potentially Affected
Downgradient Region
                                                                C R A  Boundary
                                                                  Type 4
                                                                  Gradient-Based
                                                                  Boundary
                         EXPLANATION


                          Fociity / Activity

                          Hypothetical center of pumping

                          Generalized flow direction

                          Limiting f lowtine / Type 4 Boundary


                     •V-   Stagnation Point

                    CRA  Classification Review Area
                                    A-34

-------
     Under  the worst-case  flow pattern scenario,  no ground
 water  from  the  facility/activity  can cross  the  limiting
 flowline  and enter the upgradlent region.  The only mechanism
 for  contaminants  to enter  the  upgradient  region  would be by
 chemical  diffusion  and  mechanical  dispersion  across  the
 flowline.   Because these mechanisms  may be  operable under a
 worst-case  scenario,  the Agency  considers Type  4 boundaries
 to   offer  an  intermediate   rather  than   low  degree  of
 interconnection.
A.3.2	Example of Subdividing a Classification Review Area


     Figures  A-16 through A-18 illustrate how a hypothetical
Classification  Review Area  is subdivided  into ground-water
units.    It  should  be emphasized  that  for  purposes  of  an
actual  classification  decision  not  all  the  subdivisions
illustrated  here would  be  necessary,  as  only the  ground-
water relevant  to the facility in  question would  be classi-
fied.

     The  geology of the  Classification Review Area consists
of essentially  flat-lying sedimentary formations overlying a
crystalline  basement composed of  undifferentiated granitic
and metamorphic rocks.    Three local aquifers  and  two aqui-
tards are  recognized in the area.   The uppermost aquifer is a.
water-table aquifer  defined as the  saturated  part  of a sand
and gravel deposit  overlying a low-permeability shale forma-
tion.   This  aquifer  is  recharged  by the infiltration  of
precipitation  and  discharges primarily  to the stream  and
wetland  areas.    It  is  locally  used  for  water   supply  by
domestic wells in a nearby residential development.

     Figure  A-16  shows  a  deeper  middle  aquifer that  is
interbedded  between  two  regionally extensive  shales  that
serve as  aquitard  confining beds.   Ground water  is pumped
from the  middle aquifer at  a municipal  well  that supplies
water to a nearby city.   The city also receives water pumped
from deeper well* in the lower aquifer; however, these wells
are located on  the  other side of the city  off the  left edge
of Figurer A-16.   Pumpage  from these wells  has caused  sea
water tot  intrude  into  the  lowest  aquifer froa   the  ocean
(located  off the  right  edge of  Figure  A-16).    The  lower
aquifer  is underlain  by  crystalline rocks which have  low
permeabilities and are not used as an aquifer in the area.

     Figure A-17 illustrates  the cylinder-shaped  volume  of
earth material that underlies the Classification Review Area.
The  ground-water regime  is  defined to  include all grcur.d
water and earth materials  between the  water tabla  in  the
uppermost  aquifer and the contact between  the lower aquifer
and the basement rocks.  Figure A-18 shows how the regime can

                             A-35

-------
                                                       FIGURE  A-16



         HYPOTHETICAL SETTING FOR DEMONSTRATING THE SUBDIVISION OF A CLASSIFICATION  REVIEW AREA
                                                                  City
i
u>
(ft
       iJvirirLTLTirirLriTrLriJiririJiririrvir
rt^tj^-T^-K-!^-T^*^7^^r^Tr^r^iir«L*^-^j^jtL^_*^L**-*^-^ ** ™*-"^TT "*_

                                                ^"iTiTirxiririrvirtriTirirvLrLriiJVirir'ir^

-------
               FIGURE A-17


HYPOTHETICAL CLASSIFICATION REVIEW AREA
                                                     Mlddl*
                                                     Low«r
                                                     Aquifer
                A-37

-------
                           FIGURE A-18

    SUBDIVISION OF A HYPOTHETICAL CLASSIFICATION
               AREA  INTO THE GROUND-WATER UNITS
                                               TYPE  I
                                               BOUNDARY
UNlT I
                                                          UNIT 2
                                                           TYPE 2
                                                           BOUNDARY

                                                           UNIT 3
                                                           TYPE 2
                                                           BOUNDARY
                                                        TYPE 3
                                                        BOUNDARY
                                                             UNJT

-------
 be subdivided into five ground-water unit*.  For purposes of
 an actual  classification decision,  only the"ground-water unit
 that could potentially  be  affected by the facility would be
 pertinent.

      Ground-water units 1 and 2  are subdivided  along a Type l
 ground-water flow divide bourclary beneath the  sinuous peren-
 nial river.   This boundary is inferred from a  napping of the
 flow pattern  within  the uppermost  aquifer.    The aquitard
 beneath  the aquifer  exhibits no evidence of discontinuities
 within the Classification Review Area.  It is  present in all
 deep wells in the area  and consistently shows  large vertical
 gradients  across it.   Even so,  the  estiaate of the rate of
 ground-water flow per  unit  area through the unit  (based on
 these gradients and  hydraulic conductivities)  is no greater
 than 10'6  cm/sec,  which is negligibly  small  relative  to
 ground-water flow rates in adjacent  aquifers.   Based on these
 characteristics,   the  aquitard  constitutes  a Type  2  low
 hydraulic  conductivity, non-aquifer  boundary.   The vertical
 extent of  ground-water  units 1  and  2  is  thus  delineated by
 the  existence of  this physical boundary.

      Ground  water within the middle aquifer is identified as
 a  third  ground-water unit with  the overlying and underlying
 aquitards constituting  Type 2 boundaries.  In addition to the
 characteristics  described above for  the uppermost aquitard,
 long-term aquifer tests have been performed on the municipal
wells completed in the  middle and lower aquifer.  These tests
 indicate that  less than  10 percent  of water pumped from the
 aquifers is  derived  from the leaking  aquitards,  thus their
designation as Type 2 boundaries is justified.

     Ground  water  within  the  lower  aquifer   is  generally
moving towards  a major pumping center located outside of the
Classification Review Area.   A significant part of the water
 in  this  aquifer  has  been replaced  by sea  water having IDS
concentrations  in excess  of 30,000  mg/L.   The  problem has
been  studied by  the U.S.  Geological Survey  in cooperation
with  the city.   The  movement of the interface between fresh
and  saline water  is  being monitored with a few deep wells
 (not  shown  in the illustrations).   The approximate location
of the interface at the time  of subdivision was approximately
known and, lacking specific TDS  data, is taken as the 10,000
mg/L  TO* Type) 3 boundary separating ground-water units 4 and
 5  on Figur*  A-18.     Because the  actual  10,000 mg/L TDS
boundary is probably  several  hundred  feet further towards the
wej.1  field,   use of  the  interface  as  this boundary makes
ground-water  unit 4 larger and  unit 5 smaller than they may
actually be.   However,  lacking  specific data,  such  use of
reasonable  and  conservative  assumptions  is  necessary and
appropriate.
                             A-39

-------
A. 4         Appendix A References
Freeze,  R.A.  and J.A.  Cherry,  1979.   Groundwater. Prentice-
     Hall, Inc.   Englewood Cliffs, NJ.


Geraghty fc  Killer, Inc.,  1984.   Stochastic Model of Correc-
     tive Action costs at Hazardous Waste Management Facili-
     ties.   Final Report prepared for USEPA, office of Solid
     Waste; Annapolis,  Maryland.

Heath,   R.C.,  1984.    Ground-Water  Regions  of  the  United
     States.  U.S.  Geological Survey Paper 4, U.S. Government
     Printing Office, Washington, DC.


Todd,  David  X.,   1976,  Ground Water Hydrology,  John  Wiley 6
     Sons, Inc.,  New YorJc.


U.S. Environmental Protection Agency,  1985.   Draft Report-
     Liner Location Risk and Cost Analysis  Model.  Appendix
     c.   Office  of Solid  Waste,  Economic  Analysis  Branch;
     Washington,  DC
                             A-40

-------
       APPENDIX B
SUPPLEMENTAL INFORMATION
  FOR CLASS I PROCEDURES

-------
                          APPENDIX B

       SUPPLEMENTAL INFORMATION FOR CLASS I PROCEDURES
B.I  Densely Settled Criterion
     The determination of a substantial population is related
to private  wells in a densely  settled  area (i.e.,  a census-
designated densely settled area).  Urbanized areas and Census
Designated  Places  (CDPs)   also  by  definition  are  densely
settled.    The  latter  are  unincorporated  places  with  a
population density of  at least 1,000 persons per square mile
(e.g.,  500  persons located within a 0.5  square  mile area).
They are outlined on Census tract naps for metropolitan areas
and on block-numbering area maps in non-metropolitan areas of
less than 10,000 people.

     Key terms used by the Census Bureau are as follows:


     e    Metropolitan statistical area (MSA):  (a)  a city of
          at least 50,000 population, or (b) a Census Bureau-
          defined urbanized  area  of  at least 50,000  with a
          total  metropolitan  population of  at  least 100,000
          (75,000 in New England).  There are 277 HSAs (as of
          June 30, 1984).  Every  state  has at least one MSA.


     •    Urbanized area (UA):  a  population concentration of
          50,000 or more,  generally  consisting of  a central
          city together with  its  surrounding densely settled
          contiguous territory or suburbs  (the urban fringe).
          There are about 420 UAs.

     e    Prban place;  any population living within urbanized
          areas; or places of  2,500 or more  people outside
          urbanized areas.

     e    Densely nettled  area; not  an  official  statistical
          division, but used by the Census Bureau to indicate
          an area with a population density of at least 1,000
          persons per square mile within an urbanized area or
          Census Designated Place  (CDP).


                             B-l

-------
      Urbanized Areas nay include areas which  do  not qualify
 as  densely settled  (e.g., leas than 1,000 persons per square
 mile)  but  are  included within  such  geographic  boundaries
 because  of one of the following reasons:


      e     Eliminate  enclaves  of less  than  5 square  miles
           which are surrounded by built-up areas.

      •     Close  indentations  in the  boundaries   of densely
           settled areas that are no more  than 1  mile across
           the  open  end  and  encompass  no more  than  5 square
           miles.

      •     Link outlying areas of qualifying density, provided
           that the outlying  areas are as follows:

           Connected by road to, and are not  more  than 1 1/2
           miles from, the main body of the urbanized area.

           Separated from the main body of the urbanized area
           by water or other  undevelopable area, are connected
           by road to the main body of the urbanized area, and
           are  not more than  5 miles from the main body of the
           urbanized area.

      e     Are  nonresidential  urban  areas  (e.g.,  industrial
           parks,  office areas, or major airports), which have
           at least one-quarter of their boundaries contiguous
           to an urbanized area.


     MS As  and  their components are listed in the i960 census
 of  Population  -Supplementary  Report;   Metropolitan Statis-
 tical  Areas   and  are  mapped  on  State  MSA  outline  maps.
 Urbanized  area   (UA)  outline  maps  are generally contained
 within MSA publications.
B.2  Use of 6EXS System for Estimating Well Density
     Onsj  Beans  of estimating  private well  usage  in areas
where no  local information on  private  wells  is available is
to  use* population data for  the area  of  interest available
through  the  Graphical  Exposure  Modeling  System   (GEMS)
maintained  by EPA's office  of Toxic Substances  (OTS),  or a
private census data service.

     Information  on  the GEMS system  is available from EPA's
OTS  modeling team.   Using  the GEMS  Census  Data  (CO)  pro-

                              B-2

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 cedure,  it is  possible to  retrieve population  and housing
 count  data from the  1980  Census for circular areas around a
 point,  which  can be  designated  using latitude and  longitude
 coordinates  or the  ZIP code  of  the location.    The system
 provides  information  within defined concentric rings ranging
 from  0.1  to 10,000 km  in  radii.   It is necessary to supply
 the  number of sectors  into  which the rings are divided; the
 procedure  allows  from 1 to  16.   Sectors are numbered clock-
 vise  with the  first  sector centered  at  zero  degrees   (the
 north  compass point  direction).   The program tabulates total
 population and housing  counts by ring distance and sector.  A
 simple  mathematical  conversion can be  used to transform the
 population counts into density.

     The manner in which population data are recorded by the
 Bureau  of the  Census  and  reported  by  GEMS  can  result in
 reports  of no  population  for   some  areas where  people are
 living.   This  information can  be verified or  corrected by
 consulting local  officials.   It  is unlikely that such areas
 would satisfy the densely settled test, however.
B.3  General  Background  Information  on Institutional  Con-
     straints
     Institutional constraints  on the  availability of water
can arise  from  at least six general  sources.   Each of these
is discussed below.

State Law

     State law creates basic rights to the withdrawal and use
of  surface and ground  water.   For  example,  State  law may
regulate the rights to or ownership of water; the withdrawal,
uses, and allocation of water; conjunctive use of surface and
ground  water;  protection  of in-stream users;  and measures
required to  protect  ground water.   The law in most states,
however, does  not create a  right  to unlimited  amounts of
water, and may restrict  where the water may be used  (Council
of  State  Governments,  1983).    The  States  have  created
different  methods  for  establishing  rights  to   water  and
resolving  conflict*  over rights  to withdraw  and use water.
There are  three major systems  of regulation  of water with-
drawal and use:


     •  The Eastern  (common  law)  doctrine,  used in about 3?
        states, provides that ownership of land carries with
        it a right to water in adjacent lakes or watercourses
        (a riparian  right)  and to  water beneath  the  land.

                             B-3

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        The  use  of the  water,  however,  nay  be restricted.
        Under  the absolute  use doctrine,  itT is possible for a
        landowner  to  withdraw  unlimited amounts  of  water,
        without liability for damage to other landowners, and
        to  transport  the  water off  the  land.    Under  the
        reasonable-use doctrine, it is  possible to withdraw
        an amount of water  necessary for  the use or enjoyment
        of the overlying  land, but the water may not be tran-
        sported away from that  land.  Under the correlative-
        rights doctrine,  the right  to withdraw ground water
        is based on the relationship between the size of the
        aquifer and the area of  the overlying land.

     e  The  Western (appropriation)  doctrine, used in about
        13 states, provides that water is a public resource,
        and  right* to  water may be acquired  by actual use.
        Conflicts in priority of use  are ordinarily settled
        by the principle  of "first in time, first in right."
        Hierarchies of use, however, may  also be established.

     e  Permit systems, used in about 31 states, may be used
        in conjunction with the common law or appropriation
        doctrines, and may be   applied to  surface and/or to
        ground water.   Rights to water under a permit system
        are  acquired by  application to a regulatory author-
        ity.    If the  authority determines that no superior
        claim   exists  to  the  water,  it  records  the  claim,
        issues a permit for use, and polices the actual use.
        Permit systems may  co-exist with  other forms of water
        regulation, such  as designated ground-water protec-
        tion zones or management areas.  Many permit systems
        specify priorities  for  different  types of  uses of
        water   (beneficial  uses),  generally  making domestic
        use, such  as  drinking water,  the highest  beneficial
        use  and  Baking  other   uses,  such as  commercial or
        industrial use and  irrigation,  lower beneficial uses.


     Conflicts among  users,  or prospective users,  of water
are resolved by most states in  three ways:  the conflict may
be  decided  by  the  administrative   organization  that  ad-
ministers the  water rights system in the State, particularly
if water use; permits are required; special organizations may
be crea&stf to  resolve water disputes; and the State or local
courts  Wj&-  resolve; disputes.    State  lav in certain circum-
stances My  allow the  use  of  eminent domain powers to shift
water from one use to  another, or to allow physical access to
water, ' and  State  law  may grant  the  use of eminent domain to
the  Federal government  for  certain purposes.    Frequently,
when  insufficient  water  exists  for all  claimed uses, lower
beneficial uses may give  way to  higher beneficial  uses.

     Some  states  have  attempted  by law ,to   restrict or
preclude the export of water to  users  in  other states,  either

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 by  requiring  legislative  approval  of  water  exports,   by
 requiring reciprocity  agreement* with  the' states  receiving
 the water, or  by absolute prohibitions.  All  of  these  forms
 of restriction have recently been subject to legal challenge.

      A number of states,  particularly in the  West,  designate
 ground-water protection  zone*  or management areas, and  seek
 to  coordinate   surface-   and  ground-water  use  (conjunctive
 management).   Measures of conjunctive management  may  include
 restrictions   on  punping  ground  water,   requirements   for
 aquifer recharge, and well spacing requirements.   Some states
 (e.g.,  Texas,  Nebraska)  delegate aquifer protection authority
 to local administrative  bodies.

 Federal Law

      As a user of  water, the  Federal  government  generally
 defers  to state regulation  of  water.    Federal  laws  often
 pertain to Federal  and  Indian reserved  rights to water  and
 Federal activities  affecting  water.   In common  law  states,
 Federal rights  to water  are  linked to  ownership or control of
 land.    In prior appropriation  and permit states,  Federal
 agencies (e.g.,  the  Bureau of Reclamation)  register claims to
 water.    The  Federal  government may,  however, have  special
 access  to water  in certain circumstances.   Statutes  (e.g.,
 the  Oil  and  Gas  Well Conversion Act)   or executive  orders
 (e.g.,  the Executive  Order of  April  17,  1926)  may  reserve
 water rights on  Federal public  lands for particular purposes.

     For  certain categories of  Federal  lands  withdrawn  from
 the  public domain  and  reserved  for  such  uses  as national
 forests, wildlife refuges, and parks, Federal  reserved rights
 doctrine  can  provide  access to  water  irrespective of state
 law.    The  courts  have   created  this  doctrine,  which holds
 generally  that  reservation of  public  domain  lands  for a
 particular purpose  carries with it an implied  reservation of
 sufficient water to satisfy the  purposes for which the  land
 was  reserved.    The  right  is  not  created by use  or  lost
 through  non-use.   Therefore, in certain circumstances, even
 if the  water is  being used  by another  person,  the  Federal
 government can obtain  water  for its own use.  The purpose of
 the watar i»  determined  as  of  the time  the land  reservation
 was  created,   and  the reserved  right  is  limited to that
 purpose.   (For  exaaple,   if the reservation  was  created  to
provida  agricultural  land,   reserved  rights   to   irrigation
water nay exist, but  there  are  no  reserved rights to water
 for industrial purposes.)

     An   Indian-reserved right,  similar  to  the   Federal
reserved  right,  has also been  created by  the courts.  This
doctrine  is  apparently   based  on the  presumption that  in
creating an Indian  reservation ths resident and/or Congress
 intended to reserve sufficient water for  the use of the  land.
 Indians  may  hold superior  rights  to  water  connected  with

                             B-5

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 reservation lands.    Apparently,  such  rights  may be  sold,
 although it  is  unclear whether  only  the  amount of  water
 actually being  used  or the. entire  potential  right may  be
 transferred.     in  addition  to reserved  rights,   in  a  few
 instances Indians  also hold  special  water rights based  on
 treaties (e.g.,  Treaty of Guadalupe Hidalgo).

      Federal  water  resource  agencies,  such as the Corps  of
 Engineers,  the  Bureau of Reclamation,  and  the  Soil  Conser-
 vation  Service,  as well as such Federally chartered agencies
 as  the  Tennessee Valley Authority and  the Bonneville  Power
 Authority,  can affect water availability,  either through the
 water  rights  that  they  hold  or  through their  decisions
 concerning  water management  (Congressional Budget  Office,
 1983).   Numerous other  Federal  agencies and laws  can affect
 water-resource  decisions   indirectly.     Examples of   such
 agencies or laws include the Forest Service and  Bureau  of
 Land  Management  (right-of-way  decisions),  the   Fish  and
 Wildlife Service  (requirements  under the  Fish  and wildlife
 Coordination   Act),  the  National  Environmental  Policy  Act
 (Environmental Impact Assessment  requirements), Clean  Water
 Act  (dredge and  fill  permit  requirements),  and  the Wild and
 Scenic   Rivers  Act  and  National  Wilderness  Preservation
 requirements.

 Interstate  Compacts

      Conflicts  among  two  or more  states  or  the  Federal
 government  concerning rights  to water  in streams generally
 are  resolved  either through  interstate compacts  or  through
 litigation  (Clyde, 1982, 1984;  Schwartz,  1985;  Sporhase vs.
 Nebraska,  1984).   The  result in either  case is  usually a
 decision allocating  the  in-stream  flow  among  the  states
 claiming the water.   In a few  cases,  ground water has also
 been  allocated  among  states by interstate compact or  court
 decision.

      Interstate  compacts  are  agreements  among states  that
 have  been ratified by the  legislatures of the participating
 states  and  the U.S. Congress.  The compact creates a binding
 law  within the  participating states and  a binding contract
 among the states.   In certain cases, the  Federal government
 also  joins  the compact, and the compact is then also binding
 on  they  Federal  government.    The  members   and powers of the
 compacts* currently in existence vary widely, from bilateral
 agrecMifts)   (e.g.,  Snake  River  Compact  between  Idaho  and
Wyoming} to  agreements  affecting  large  numbers  of  states
 (e.g.,  Colorado  River  Compact),  and  from compacts exclusively
devoted to. allocating  river water  (e.g., Arkansas  River
Compact of  1949)  to  compacts  establishing regional  multi-
purpose water resources  management  (e.g., Delaware  River
Basin  Compact).     Approximately  25  interstate  compacts
currently are  in operation.


                              B-6

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      In the  absence of  a resolution  of  Conflicting claims
 through an interstate compact,  litigation  among states before
 the U.S. Supreme Court may  be  the only means to resolve the
 conflict.    in  deciding  such  cases,  the  Court  ordinarily
 attempts to  carry  out "an  equitable  apportionment  of the
 interstate  stream.    Because the Court has  been called upon
 less frequently to resolve disputes among states over ground
 water,  the  standard  used  in  such cases  is  less clear.

 Local Regulations

     Local   administrative  bodies  with  jurisdiction  over
 sources of  water in  particular  areas may exercise powers such
 as  well  spacing  and  pumping  rates  that  affect  the avail-
 ability of water.   As previously  nottd,  State legislatures
 may delegate  power to local  bodies to administer  particular
 aspects of  the water  allocation or  water protection system in
 the state.   Examples  of  such  local  agencies include under-
 ground   water   conservation   districts  (Texas),   which  are
 empowered  to  provide  for spacing  of  wells  and  to regulate
 well pumping  in order to  minimize  the drawdown  of the water
 table;  ground-water  management  districts  (California), which
 are authorized  to manage  ground-water withdrawals; and water
 conservation  districts (Nebraska),  which  are authorized  to
 regulate  ground-water use.  Other  special purpose districts
 may also  affect  water  availability.    The Texas  Harris-
 Galveston   coastal   subsidence   district,   for  example,  is
 authorized to regulate withdrawal of ground water in order to
 limit land subsidence.

 Treaties and International Laws

     Treaties  between the United  States  and its  neighbors,
 Mexico  and Canada,  allocate  the  waters  of  rivers  flowing
 between the countries.  The 1944 Treaty of Utilization of the
 Waters  of  the Colorado   and  Tijuana   Rivers  and  the Rio
 Grande,   for example,  apportions  the waters  of  those rivers
 between  the  two  countries  and   creates  an  International
 Boundary and Water Commission  (IBWC)  to apply the  treaty and
 settle  disputes.   Although  ground water  use is  not  fully
 covered  by  the  treaty,  the IBWC has attempted to address the
 management of International ground-water resources.

     In addition  to  treaties  signed  by the United States,
 certain international law proposals  being developed  by the
 United  Nation* and   the   International  Law  Association may
 sometime  in the future establish general  principles for the
 allocation  of ground  and surface  waters  between  two  coun-
 tries.

 Property Law

     State  lav  governs the  ownership and  use of  land.  In
particular, property law  affects  physical   access  to  water

                             3-7

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 supplies through  restrictions on rights of way and easements,
 or defining powers of eminent  domain.   State and local lavs
 generally regulate land use and access to land by persons who
 are not. landowners.  Access to water, including the location
 of pipes, storage, pumping,  treatment, and other facilities,
 can be  delayed  or  restricted by  the  property rights  of
 persons  whose  land  must  be  crossed  or  used  for  such
 facilities.   Special procedures,  such as easements,  eminent
 domain, and condemnation, may be required to obtain necessary
 rights-of-way.   Special  procedures vary from state to state.
 B.4   List  of  offices  of Endangered  Species,  U.S.  Fish and
      Wildlife  Services
     The  Fish  and  wildlife  Service,  a  unit  of the  U.S.
Department  of  the  Interior,  has  been  delegated the  main
responsibility  for  coordinating national  and international
efforts on behalf  of Endangered  Species.

In  the case  of marine species, however, actions are taken in
cooperation  with  the  Secretary  of  Commerce,  through  the
Director  of  the  National Marine  Fisheries Service.   simi-
larly,  in the  area  of import/export  enforcement  for Endan-
gered  plants,  the Department of Interior cooperates with and
is  assisted by the  Department of Agriculture through  the
Animal and Plant Health Inspection  Service.


PROGRAM MANAGER—ENDANGERED SPECIES
Associate Director-Federal Assistance
U.S. Fish and Wildlife Service
U.S. Department of the> Interior
Washington, D.C.  20240
  Telephone:  202/343-4646

CATEGORY COORDINATOR—ENDANGERED SPECIES
Deputy Associate Director—Federal Assistance
U.S. Fish and Wildlife Service
w.s. Department of the Interior
Washington, D.C.  20240
  Telephone:  202/343-4646

Office of Prograa Development and Administration
U.S. Fish and Wildlife Service
1000 North Glebe Road, Room 629
Arlington, Virginia
  Telephone:  703/235-1726, 7, 8
                             B-8

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      Mailing Address for Office  of  Program Development
      and Administration

      U.S.  Fish and wildlife  Service
      Washington,  D.C.   20240
 Office  of  Endangered Species
 U.S.  Fish  and  Wildlife  Species
 1000  North Glebe  Road,  Suite  500
 Arlington,  Virginia
  Telephones   703/235-2771, 2

      Mailing Address for Office of Endangered Species

      U.S.  Fish and wildlife Service
      Washington,  O.C.   20240
Branch of Biological Support
Telephone:  703/235-1975, 6, 7

Branch of Management Operations
Telephone:  703/235-2760, 1, 2
Federal Wildlife Permit Office
U.S. Fish and Wildlife Service
1000 North Glebe Road, suite 600
Arlington, Virginia
  Telephone:  703/235-1937, 8, 9

     Mailing Address for Federal Wildlife Permit Office

     U.S. Fish and Wildlife Service
     Washington, O.C.  20240
Division of Lav Enforcement
U.S. Fish and Wildlife Service
1735 K Street, NW., Third Floor
Washington,  D.C.
  Telephone!  202/343-9242
     P.O. Box 28006
     Washington, O.C.  20005


Sp«cial~Ag«nt-in-Charge, Branch of Investigations
  Telephone:  202/343-9242

                             B-9

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Office of the Scientific Authority
U.S. Fish and Wildlife Service
1717 H Street, NW. , Room 536
Washington, D.C.
  Telephone:  202/653-594-8, 49, 50
     Mailing Address  for Office of the Scientific Authority

     U.S. Fish and. Wildlife Service
     Washington, O.C.  20240


Regional Endangered Species Coordinators

The  U.S.  Fish  and wildlife  Service  is  comprised of  seven
Regional Offices.   Each  office has a senior official  who has
been designated as a  Regional Endangered Species Coordinator.
Additionally, each of the regions has several Field Offices.
Problems  of  a  local nature  should  be  referred to  these
offices.


Region 1  Regional Director
          U.S. Fish and Wildlife Service
          Suite 1692, Lloyd 500 Building
          500 NE. Multnomah Street
          Portland, Oregon  97232
            Telephone:  503/231-6131    (FTS:  8/429-6131)


Field Offices

        California
        1230 "N" Street, 14th Floor
        Sacramento, California  95814
          Telephone:  916/440-2791     (FTS:  8/448-2791)

        Idaho
        4696 Overland Road, Room 566
        Boise, Idaho  83705
          Telephone:  208/334-1806     (FTS:  8/554-1806)
       Great Bavin Complex
       4«*0 Kietzke Lane, Building C
       Reno, Nevada   89502
         Telephone:   702/784-5227     (FTS:  8/470-5227 or
       •                                        5228)

       Washington/Oregon
       Building-3, 2625 ParJcmont Lane
       Olympia, Washington   98502
       Telephone:  206/733-9444       (FTS:  8/434-9444)
                             B-10

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        Pacific Islands  Administrator
        300 Ala Moana  Boulevard, Room 5302  "
        P.O.  BOX 50167
        Honolulu,  Hawaii  96850
          Telephone:   808/546-5608  '   (FTS:   8/546-5608)


 Region  2   Regional Director
          Endangered Species Specialist
          U.S.  Fish and  Wildlife Service
          500 Gold Avenue, SW.
          P.O.  Box 1306  -
          Albuquerque, New Mexico  87103
           Telephone:   505/766-3972    (FTS:  8/474-3972)


 Field Offices

        Arizona
        2934 West Fairmont Avenue
        Phoenix,  Arizona   85017
          Telephone:  602/241-2493    (FTS:  8/261-2493)

        New Mexico
        P.O. BOX  4487
        Albuquerque, New Mexico  87196
          Telephone:  505/766-3966    (FTS:  8/474-3966)

        Oklahoma/Texas
        222 South Houston, Suite A
        Tulsa, Oklahoma  74127
          Telephone:  918/581-7458    (FTS:  8/736-7458)

        Texas
        C/o CCSU, Box 338
        6300 Ocean Drive
        Corpus Christ!, Texas  78411
          Telephone:  512/888-3346    (FTS:  8/734-3346)

        Fritz Lanham Building, Room 9A33
        819 Taylor Street
        Port Worth, Texas  76102
          Telephone:  817/334-2961    (FTS:  8/334-2961)

Region j  Regional Director
         Endangered Species Specialist
      •   U.S. Fish and  wildlife Service
         Federal  Building, Fort Snelling
         Twin Cities, Minnesota  55111
           Telephone:  612/725-3276    (FTS:  8/725-3276)
                            B-ll

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 Region 4   Regional Director               „
          Endangered Species Specialist
          U.S.  Fish and wildlife Service
          The Richard B.  Russell Federal Building
          75 Spring Street SW.
          Atlanta,  Georgia  30303
           Telephone:   404/221-3583     (FTS:  8/242-3583)

 Field  Offices
        Alabaroa/Arkansaa/Louisiana/Misaissippi
        Jackson Mall Office Center
        300 Woodrow Wilson Avenue, Suite 3185
        Jackson, Mississippi 39213
          Telephone:   601/960-4900     (FTS:  8/490-4900)

        Florida/Georgia
        2747 Art Museum Drive
        Jacksonville,  Florida 32207
          Telephone:   904/791-2580     (FTS:  8/946-2580)

        Kentucky/North  Carolina/South  Carolina/Tennessee
        Plateau Building,  Room A-5
        50 South French Broad Avenue
        Asheville,  North  Carolina 28801
         Telephone:   704/258-2850 ext. 382
                      (FTS:   8/672-0321)

        Puerto RicoZVirqin Islands
        P.O. Box 3005
       Marina Station
       Mayaguez, Puerto  Rico 00709
         Telephone:   809/833-5760     (FTS:  8/967-1221)


Region  5  Regional Director
         U.S.  Fish and wildlife Service
         Suite 700, On*  Gateway Center
         Newton Corner,  Massachusetts 02158
           Telephone:   617/965-5100 ext. 316
                        (FTS:  8/829-9316, 7, 8)

Field Office*

        Cfltuietcticut/Mainc/Varmont/Massachusetts/New
            Hpup^htt^/Rhode Island
        P.O. BOX 1518
       •Concord, New Haapshire   03301
         Telephone:   603/224-9558, 9    (FTS:  8/834-4726)

       District of Colufflfrjaypelaware/Marvland
         Virginia/West Virginia
        1825 Virginia Street
       Annapolis,  Maryland   21401
         Telephone:  301/269-6324     (FTS:  8/922-4197)

                             B-12

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        New Jersey/Pennsylvania             ^
        112 West Foster Avenue -
        State College, Pennsylvania   16801
          Telephone:  814/234-4090     (FTS:   8/727-4621)
        New York
        100 Grange  Place
        Cortland, Naw York   13045
          Telephone:  607/753-9334     (FTS:   8/882-4246)

Region  6   Regional Director
          U.S. Fish and Wildlife Service
          P.O. Box 25486, Denver Federal Center
          Denver, Colorado   80225
            Telephone:  303/234-2496     (FTS:  8/234-2496)

Field Offices

        Colorado/Utah
        Room 1406, Federal Building
        125  S. State Street
        Salt Lake City, Utah   84138
          Telephone:  801/524-4430     (FTS:   8/588-4430)

        Kansas/Nebraska/North  Dakota/South Dakota
        223  Federal Building
        P.O.  Box 250
        Pierre, South Dakota   57501
         Telephone:  605/224-8692     (FTS:   8/782-5226)

       Montana/Wyoming
        Federal Building,  Rooa 3035
        316 North 26th Street
        Billings, Montana  59101
         Telephone:  406/657-6059 or  6062
                     (FTS:  8/657-6059)

Region  7  Regional Director
         1011 E. Tudor Road
         Anchorage, Alaska  99503
         Telephone:  907/786-3435
                        (FTS:  8/907/786-3435)
                             B-13

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B.5  List  of  State Natural Heritage Program Offices  (October
     1985)
Nongame Branch
ARIZONA HERITAGE PROGRAM
Arizona Game & Fish Department
2222 W. Greenway Road
Phoenix, Arizona  85023
  Telephone:  602/942-3000 ext. 245

ARKANSAS NATURAL HERITAGE INVENTORY
225 E. Markham, Suite 200
Little Rock, Arkansas  72201
  Telephone:  501/371-1706

CALIFORNIA NATURAL DIVERSITY DATABASE
c/o CA Department of Fish 6 Game
1416 9th Street
Sacramento, California  95814
  Telephone:  916/322-2493

COLORADO NATURAL HERITAGE INVENTORY
Department of Natural Resources
1313 Sherman Street, Room 718
Denver, Colorado  80203
  Telephone:  303/266-3311

CONNECTICUT NATURAL DIVERSITY DATABASE
Natural Resource center
Department of Environmental Protection
State Office Building, Room 553
165 Capitol Avenue
Hartford, Connecticut  06106
  Telephone:  203/566-3540

FLORIDA NATURAL AREAS INVENTORY
254 E. 6th Avenue
Tallahassee, Florida  32302
  Telephone:  904/224-8207

HAWAII HERITAGE
1116 Smitt* Street, #201
Honolulu, Hawaii  96817
  Telephone:  808/537-4508

IDAHO NATURAL HERITAGE PROGRAM
4696 overland Road, Suite 518
Boise, Idaho  83705
  Telephone:  208/334-3402 or 3649
                             B-14

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 INDIANA HERITAGE PROGRAM
 Division of Nature Preserves,  IN DNR
 612 State Office Building
 Indianapolis, Indiana  46204
   Telephone:  317/232-4078

 IOWA NATURAL AREAS INVENTORY
 State Conservation Commission
 Wallace State Office Building
 Des Moines,  Iowa  50319
   Telephone:  515/281-8524

 KENTUCKY HERITAGE PROGRAM
 Kentucky Nature Preserves commission
 407 Broadway
 Frankfort,  Kentucky  40601
   Telephone:  502/564-2866

 LOUISIANA NATURAL HERITAGE PROGRAM
 Department of Natural Resources
 Coastal Management Division
 P.O.  BOX 44124
 Baton Rouge,  Louisiana  70804-4124
   Telephone:   504/342-4602

 MAINE NATURAL HERITAGE PROGRAM
 Maine Chapter
 122 Main Street
 Topsham,  Maine  04086
   Telephone:   207/729-5161

MARYLAND NATURAL HERITAGE AND ENVIRONMENTAL REVIEW
 Department of Natural  Resources
 C-3,  Taves state Gfflce  Building
Annapolis, Maryland   21401
  Telephone:   261-1402,  3656 or 269-3656

MODEL NATURAL HERITAGE PROGRAM
The Nature Conservancy
 1800  N.  Kent  Street,  suite  800
Arlington, Virginia   22209
  Telephone:   703/841-5307

MASSACHUSETTS  HERITAGE PROGRAM
Division of  Fisheries and Wildlife
100 Cambridge Street
Boston-,  Massachusetts  02202
  Telephone:   517/727-9194

MICHIGAN NATURAL FEATURES INVENTORY
Mason Building,  5th floor
Box 30028
Lansing, Michigan  48909
  Telephone:   517/373-1552

                             B-15

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 MINNESOTA NATURAL HERITAGE  PROGRAM
 Department of Natural Resources
 Box 6
 St.  Paul,  Minnesota  55155
   Telephone:   612/296-4284

 MISSISSIPPI NATURAL HERITAGE PROGRAM
 111 N.  Jefferson street
 Jackson,  Mississippi  39202
   Telephone:   601/354-7226

 MISSOURI  NATURAL HERITAGE INVENTORY
 Missouri  Department of Conservation
 P.O.  Box  180
 Jefferson City,  Missouri  65102
   Telephone:   314/751-4115

 MONTANA NATURAL  HERITAGE PROGRAM
 State Library Building
 1515  E. 6th Avenue
 Helena, Montana   59620
   Telephone:   406/444-3009

 NAVAJO  NATURAL HERITAGE PROGRAM
 Box 2429
 Window  Rock,  Arizona  86515-2429
   Telephone:   602/871-6453  or 5449

 NEVADA  NATURAL HERITAGE PROGRAM
 Department of Conservation  and Natural Resources
 c/o Division  of  State Parks
 Capitol Complex,  Nye Building
 201 S.  Fall Street
 Carson  City,  Nevada  89710
  Telephone:   702/885-4360

NEW HAMPSHIRE NATURAL HERITAGE PROGRAM
c/o Society for  the Protection of N.H. Forests
54 Portsmouth Street
Concord, New  Hampshire 03301
  Telephone:  603/224-8945

NEW JERSW NATURAL HERITAGE PROGRAM
Office oft natural Land* Management
 109 w. S«ate  street
Trenton, Sttv  Jersey  08625
  Telephones  609/984-1339  or 1170

NEW MEXICO NATURAL RESOURCES SURVEY SECTION
Villagra Building
Santa Fe,  New Mexico  87503
  Telephone:  505/827-7862
                             B-16

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 NEW YORK NATURAL HERITAGE  PROGRAM
 Wildlife Resources Center
 Delmar,  New YorJc 12054-9767  .
   Telephone:   518/439-8014 ext.  203

 NORTH CAROLINA NATURAL HE'RITAGE
 Jepartment  of  Natural and  Economic Restoration
 Division of State Parks
 Box 27687
 Raleigh,  North Carolina  27611
   Telephone:   919/733-7795

 NORTH DAKOTA NATURAL HERITAGE INVENTORY
 North Dakota Game and Fish Department
 100 N. Bismarck  Expressway
 Bismarck, North  Dakota  58501
   Telephone:   701/221-6310

 OHIO NATURAL HERITAGE PROGRAM
 Ohio DNR, Division of Natural Areas  and  Preservation
 Fountain Square, Building  F
 Columbus, Ohio  43224
   Telephone:   614/265-6453

 OKLAHOMA NATURAL HERITAGE  PROGRAM
 Oklahoma Tourism and Recreation  Department
 500 will Rogers  Building
 Oklahoma City, Oklahoma  73105
   Telephone:   405/521-2973

 OREGON NATURAL HERITAGE PROGRAM
 Oregon Field Office
 1234  NW  25th Avenue
 Portland, Oregon 97210
   Telephone:   503/228-9550

 PENNSYLVANIA NATURAL DIVERSITY INVENTORY
 Bureau of Forestry
 Department of  Environmental Resources
 34 Airport Road
Middletown, Pennsylvania   17057
  Telephone:   717/783-1712

PROGRAMA PRO-PATRIMONIC NATURAL
Apartado 5887
Puerta de Tierra, Puerto Rico  00906
  Telephone:   809/724-0960

RHODE ISLAND HERITAGE PROGRAM
Department of  Environmental Management
Division of Planning and Development
22 Hayes Street
Providence, Rhode Island   02903
  Telephone:   401/277-2776

                             B-17

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 SOUTH CAROLINA HERITAGE TRUST
 S.C.  Wildlife and Marine Resources Department
 P.O.  BOX 167
 Columbia,  South Carolina  29202
   Telephone:   803/756-0014

 SOUTH DAKOTA NATURAL HERITAGE
 South Dakota Department of Game, Fish & Parks
 Division of Parks and Recreation
 Sigurd Anderson Building,  3-114
 Pierre,  South Dakota  57501
   Telephone:   605/773-4226

 TENNESSEE  HERITAGE PROGRAM
 ECOLOGICAL SERVICES DIVISION
 Tennessee  Department of Conservation
 701 Broadway
 Nashville,  Tennessee  37203
   Telephone:   615/742-6545

 TEXAS  NATURAL HERITAGE PROGRAM
 General  Land  Office
 Stephen  F.  Austin Building
 Austin,  Texas  78701
   Telephone:   512/475-0660, 0661, 0621,  0800

 TVA REGIONAL  HERITAGE
 Office of Natural Resources
 Morris,  Tennessee  37828
  Telephone:   615/494-5600

 VERMONT  NATURAL HERITAGE PROGRAM
 Vermont  Field Office
 138 Main Street
 Montpelier, Vermont  05602
  Telephone:   802/229-4425

WASHINGTON  NATURAL HERITAGE PROGRAM
 Department  of Natural Resources
Mail Stop EX-13
 Olympia, Washington  98504
  Telephone:   206/753-2448

WEST VUHZVZA WILDLIFE/HERITAGE DATABASE
wildlifar Resources Division
 DNR Operations Center
P.O. BOX 07
Elkins, West Virginia  26241
  Telephone:   304/636-1767
                             B-18

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 WISCONSIN NATURAL HERITAGE PROGRAM
 Endangered Resources/4
 Department of Natural Resources
 101 S. Webster Street, Box 7921
 Madison, Wisconsin  53707
   Telephone:   608/266-0924

 WYOMING NATURAL HERITAGE PROGRAM
 1603 Capitol  Avenue,  Rooa 323
 Cheyenne,  Wyoming  82001
   Telephone:   303/860-9142

 NATIONAL OFFICE HERITAGE TASK  FORCE

 Vice President,  Science           841-^320
 Director,  Heritage                841-5325
 Assistant  Director                841-5367
 Director,  PS&D                    841-5322
 Budget Specialist                 841-5368
 National Ecologist            217/367-8770
 Classification Ecologist      217/367-8770
 Director,  National Database        841-5361
 National Databases Associate       841-5360
 National Information Manager       841-5360
 Microcomputer  Analyst              841-5355
 Microcomputer  Specialist          841-5355
 Senior Programmer/Analyst          841-5356
 Administrative Assistant,HFA       841-5354
 Part-time  Secretary, HFA          841-5354
 Executive  Secretary, Science       841-5321

 REGIONAL

 EASTERN  HERITAGE  TASK  FORCE
 The Nature Conservancy
 294 Washington Street
 Boston,  Massachusetts   02108
  Telephone:   617/542-1908
           r,
MIDWEST  HERITAGE  TASK  FORCE
Midwest  Regional  Office
The Nature Conservancy
 1313 Fifth Street,  SE
Minneapolis, Minnesota  55414
  Telephone:   612/379-2207

ROCKY MOUNTAIN HERITAGE TASK FORCE
The Nature Conservancy
 1370 Pennsylvania  Street, Suit* 190
 Denver,  Colorado   60203
  Telephone:   303/860-9142
                             B-19

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B.6       Appendix B References
Council   of  State   Governments,   Interstate  Compacts  and
     Agencies.  1933,  provides  annual listing  of names  and
     phone  numbers  of commissioners  of  interstate  compacts
     and  compact administrators and  citations  to state  and
     Federal legislature enactments of components.

U.S. Bureau  of  Census,  statistical Abstract  of  the  US:  1986
     (107th edition), Washington, DC 1986.
                             B-20

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        APPENDIX C
SUPPLEMENTAL INFORMATION
 FOR CLASS III PROCEDURES

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                          APPENDIX C

       SUPPLEMENTAL  INFORMATION FOR  CLASS III PROCEDURES
C.I  Overview of Treatment Technologies
     The  following  discussions  of  treataent  technologies
indicate  the  typical area of  application  and limitations of
particular  significance and  the potential  problems  encoun-
tered  when treating water  that contains  multiple contami-
nants.   A series of references  that  can be used for general
background  data  is  included.   Many   treatment  processes,
particularly  those used  in  water polishing,  develop  reduc-
tions  in treataent  efficiencies in  the presence  of  inter-
fering  contaminants, so that  pretreatment is  required.   In
existing  water-treatment  facilities,  pretreatment  require-
ments  are net  by employing successive processes  —  in an
order that progressively removes various interferences.  For
example, a facility  that receives a water with high levels of
adsorbable  organics  and  high  suspended  solids  may  use
granular  media  filtration prior to  carbon  adsorption  in an
effort  to minimize  the  levels of solids  in  the influent to
the carbon  adsorption; the load  of  solids to the adsorption
column will disrupt  this process.

     If  several  processes in  a  treatment  configuration have
disruptive interference  problems, the particular combination
of  processes cannot  be reasonably  employed  to  treat  the
water.   This  situation might  occur  if an influent contained
high  levels  of  dissolved  organics  and  inorganic chemical
oxidants, and the treataent configuration under consideration
was  a  combination  of  desalination   and  ion exchange.   The
dissolved organics,  which would  be  removed by desalination,
could aavarely  disrupt the  ion  exchange efficiencies,  while
the  chemical  oxidants  (removable  by  ion  exchange)  could
disrupt th« desalination process.  This particular treatment
configuration would,  in this  instance, be  eliminated from
further  consideration because additional  pretreatoent would
be required to manage the chemical interferences.
                             c-l

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 Air Stripping/Aeration

      Air stripping and  aeration  can be used for  removal  of
 volatile contaminants  from  ground  water,  as  well  as  for
 introduction of oxygen to  the water.   Air is passed through
 the water  or  the water  is  finely sprayed into the  air,
 enhancing transfer of dissolved gases  from  the water to the
 air,  which  may be treated  further or  discharged.    Cost-
 effective and  efficient  treatment   requires  continuous  or
 semicontinuous  flow.   The  process has  been  used  for ammonia
 removal,  hydrogen sulfide  removal,  and  volatile  organic
 carbon   removal  in  both  water  and  wastewater  treatment
 operations.    The  treatment  efficiencies and  design are  a
 function of  the contaminant loading  to the air,  water ratio,
 the  length  of contact  time,  contaminant  volatility,  and
 temperature.    Removal  efficiencies  of  volatile  organics
 ranging  from 10  percent to  greater than 99.0 percent  have
 been  reported in the literature.

     Although   air stripping is  a  relatively  inexpensive
 technology for  removal of  volatile  contaminants,  its use  in
 public   water-supply   systems  to  date  has been  somewhat
 limited.  Its  limited  use  is  due  primarily to a lack of need
 for the  technology, which  is in  widespread  use in Super fund
 remedial  action   and  wastewater  treatment  operations.
 Traditional  aeration,  which  is  in common use  among public-
 water  utilities,  has typically  been  installed  to  provide
 oxygenation  of  waters,  and  the  removal of volatile  con-
 taminants is merely a beneficial side-effect.

     Temperature  limitations  in regions  experiencing severe
 winters may be  such that air  stripping and aeration processes
 must  be  housed  indoors or in thermally protected facilities.
 If  the treated  water contains high levels of suspended solids
 (unlikely to occur with ground waters),  some  pretreatment,
 such as filtration or pH adjustment, may be required prior to
 air stripping.

     Aeration and  air  stripping pose potential  air pollution
problems  if  large amounts of  volatile contaminants  in  the
treated  waters are transferred to  the air.   If this  is  a
problem*  emission  control  devices  are required.   Most ground
water*, However, are  not likely to contain concentrations of
volatile contaminants sufficiantly large to warrant such con-
trols.

Carbon- Adsorption

     Carbon  adsorption  treatment  of  ground waters  entails
contacting the water  with activated carbon, which adsorbs
contaminants  and   removes  them  from  solution.•   Granular
activated  carbon,  used  in  beds  or  columns,  is the  most
commonly  used  form, although powdered activated  carbon has
been  used  in some  wastewater  treatment  applications.

                              C-2

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 Treatment  processes can  use both  batch and continuous-feed
 operations.   Activated carbon- adsorption effectively removes
 many  organic  and  inorganic  contaminants  from  solution.
 Treatment  efficiencies are a function  of the type of carbon
 used,  the  concentration and  type of contaminants present, the
 length of  contact  time   for  each  unit of  water,  and t'*e
 interval between carbon regeneration or replacement.  Removal
 efficiencies  ranging from  0  to greater  than 99.9 percent have
 been reported in the literature.

     Although activated  carbon adsorption  theoretically can
 provide  limitless  removal of contaminants,  in reality there
 are  economic  limitations  to the applicability  of activated
 carbon treatment.   Removal of high concentrations of contam-
 inants may require overly frequent carbon replacement, while
 hard to  remove contaminants may require enormous treatment
 facilities  with   several   carbon  contact  systems:    both
 situations  may  incur  excessive  expense,  and  though  tech-
 nically feasible would be  effectively unavailable.

     Influent to  the  carbon  adsorption  process  must  be
 relatively free of suspended solids and oil/grease to prevent
 clogging of  the adsorption  beds.   Suspended  solids  of less
 than 50  mg/L and oil/grease of less than 10 mg/L are recom-
 mended concentrations  to  avoid  interferences.    Biological
 activity  in  the carbon  beds may become a problem  in some
 instances, causing clogging and taste or odor generation.

     Removal  efficiencies in carbon adsorption  systems are
 affected by  changes in  influent flow  and  influent chemical
 composition.   The presence  of multiple contaminants  in the
 influent may  reduce adsorption efficiency  for  some  of the
 constituents,  although  in  some  instances  where  multiple
 contaminants  are  involved,   increased  removal  efficiencies
 have been  noted.   For any given  water to be  treated, the
 selection  of the  appropriate  carbon  and  system  design
 requires  laboratory  testing   to   determine  the  specific
 adsorption efficiencies and  interferences for that influent.

 Chemical Precipitation

     Cheaical  precipitation,  coagulation,  flocculation.  and
 sedimentation are  all interrelated processes that  arc most
 often  us«d   to  remove  metals  and  certain  organics  from
 solution.   For waters containing  dissolved solids,  a pre-
 cipitant is added which reacts with th« contaminant to form a
 solid,  or to  shift solution  chemistry  in such a way that the
 contaminant  solubility is reduced.    The  precipitated con-
 taminant can  then be removed  by  gravity  sedimentation  or
mechanical  solids  removal  processes.   ' commonly. used pre-
 cipitanta  include  lia«,  caustic,  soda  ash,  iron salts, and
phosphate  salts.    Some  waters  contain colloidal suspended
 solids which  cannot be  readily  removed  using  conventional
 sedimentation.   Treatment of  these contaminants,  which are

                             C-3

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 usually  organic  in nature,  entails addition  of  a coagulant
 (usually  alum,  cuprous  sulfate,  or  ferrous  sulfate)  that
 forces  the  suspended  solids  to  agglomerate  into  larger
 particles,  which  can  then  be removed  using  gravity  sedi-
 mentation.     Some  facilities  add  polymeric  coagulant  or
 precipitation aids, which have been shown to enhance removal
 efficiencies  in some cases,  chemical precipitation processes
 can be run  as batch or continuous-flow operations.  Treatment
 efficiencies  depend  upon the  contaminant  type  and  concen-
 tration   present,   the  solution   pH  and  temperature,   the
 precipitants  added, time and degree of  mixing,  and the  time
 allowed for sedimentation.

     Precipitation of metals from solution  can be inhibited
 by the  presence of chelating  agents in the  waters,  such as
 humic materials (naturally occurring organic acids) or other
 organic compounds.  This problem can be eliminated by using
 precipitants  with  stronger affinities  for the metal than the
 complexion  agent  or by using  pH  adjustment to  disrupt  the
 metal complex.

     Use  of  chemical  precipitation processes  generates  a
 sludge  that  must  be  disposed  of  appropriately.    Sludges
 containing  heavy metals or certain organics may be considered
 to be  hazardous  wastes and as such should be  disposed in
 RCRA-regulated  facilities.

 Desalination   ;

     Desalination   processes  remove  contaminants  from  the
 influent  using membranes  to  separate  an  enriched  stream
 (high-contaminant   concentration)  from  a  depleted  stream.
 Reverse   osmosis  and  ultrafiltration   use  a  pressure
 differential  to drive  the  separation, while electrodialysis
 depends on  an electric  field.  The  concentrated or enriched
 stream  frequently  requires  further  treatment,  while  the
 depleted  stream is  usually potable.   Desalination processes
 have been used to purify waters to drinking-water quality in
 certain regions of the country where fresh water is in short
 supply.     The  processes  are  in more  widespread use  for
 treatment of  industrial  process  waters  which  must be  of
 extremely  high  quality.     Treatment  efficiencies  are  a
 function  of   the  molecular  size  and  concentration  of
 contaminant*,   strength of  the  separation  driving  force,
 membraner  type,   and  system  configuration.     Removal
 efficiencies of greater than 90 percent have been reported in
 the literature.

     Desalination  processes are  highly  sensitive to  vari-
 ability in  the influent, and drastic changes in pK, tempera-
ture, or  suspended solids.  Any  of  these factors can effec-
tively reduce treatment efficiencies and  the membrane life.
The  suspended  solids  in a  desalination influent  should be
minimized to  particle  sizes 10 microns  or  less  in order to

                             C-4

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 prevent membrane  fouling.   Biological activity can severely
 impair  the  process  efficiency,   and  disinfection  may  be
 required prior to desalination.   The presence  of chlorine may
 also disrupt  efficient  desalination,  dechlorination or. non-
 chlorine disinfection processes  may be desired.

      Desalination processes  are very  expensive  and energy-
 intensive.   Because  of  this,  desalination is not  frequently
 used for removal  of contaminants that  are readily removed via
 other treatment processes.  However,  for high IDS  waters and
 waters with  large dissolved molecules,  these processes may
 provide cost-effective contaminant  removal.

 Flotation

      Flotation is used to remove oil  %nd grease or suspended
 particles  from  the  aqueous phase.    The process involves
 introduction  of a  gas (usually  air)  into  the solution,  and
 subsequent  attachment of  the  gas  bubbles   to  particulate
 matter,  which  then  floats  to  the surface.   The floating
 particulates  can  be  skimmed and  removed  for disposal  or
 further   treatment.    Surfactants  and  pH-modifications  are
 often  used  to  improve process performance.  Flotation is used
 in many  public-water utilities across the nation for removal
 of organic  matter  from  surface  waters, but the  most common
 use  of the  process is removal of oils and grease from indus-
 trial  petroleum  wastewaters.   Removal  efficiencies are  a
 function  of concentration,  size, mass of contaminant partic-
 les,   air-loading  rate,   types   of  chemical additives  used,
 hydraulic-loading  rate,  and  skimmer design.  Removal effici-
 encies  over 95 percent have been reported in the literature.

     Flotation  is effective  for contaminants  with densities
 less  than  or  near  to   that of  water,  but   is   relatively
 ineffective for contaminants denser  than water.    It  is not
 particularly  effective for  removing dissolved contaminants,
 although  chemical  additives can  be  used  to  decrease  con-
 taminant  solubility.   If  volatile contaminants are  present in
 the  influent,  flotation  may result in simultaneous stripping
 of these  contaminants from solution.

 Granular Media Filtration

     Granular  media  filtration  is  widely used  to separate
 solids  from aqueous  streams.   Water  is  fed  (via gravity or
 applied pressure)  through a bed  of granular media, which may
 consist of  sand,  gravel,  coke,  or combinations of  the three.
 Periodically  the  filter  is backwashed,  which  removes  the
 filtered  particles into a relatively  ssall volume of vaste-
water which must be disposed of  or  treated  further.  Granular
media  filtration  is commonly used in water utilities follow-
 ing chemical precipitation to ensure that turbidity standards
are met.  Filtration performance depends upon the  solubility
of the contaminant*,  the strength and size  of  contaminant

                             C-5

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particles,  the  type of  granular  aadia used,  the hydraulic
loading rate,  and the interval between backwashings.  Removal
to   suspended   solid  levels  less  than  to  mg/L  has  been
reported.

ion  Exchange

      Ion exchange processes,  like carbon adsorption, operate
by removing contaminants from solution onto a receptor.  The
ion  exchange  process uses a chemically reactive  resin that
exchanges  innocuous  ions  for the contaminant  ions in solu-
tion.   The  reaction is reversible, which allows a facility to
regenerate  the ion exchange resin and reuse it.  Ion exchange
processes  are  most  commonly used to  generate high-quality
industrial, processes  waters, but  recent  applications have
also  included  wastewater treatment  and  ion  exchange water
softening to remove hardness  in drinking-water supplies.  Ion
exchange can  be  used for removal  of almost  any  ion from
solution,  but  is  not very effective  for  removing uncharged
contaminant species.   Removal efficiencies,  which have been
reported in excess  of 99.9  percent,  are dependent upon the
ionic  charge  of the  contaminants, contaminant concentration,
type  of resin  used,  hydraulic loading,  and interval between
resin  regeneration.

     Although  almost  any ionic  contaminant  can  be removed
using   ion  exchange processes,   the   specific ion exchange
resins  used are usually specific to certain types  of contam-
inants.  Resin selectivity is based on the type (positive, or
negative)  and  degree  of  charge on the contaminant ions.  If
several   types  of  contaminants  with  varying  charge  are
present,  efficient  ion  exchange  treatment  may   require  a
series  of different resins.

     Changes  in pH  or the presence of organic and inorganic
complexing  agents  may cause certain  ionic species  to form
uncharged or differently  charged chemical complexes, which in
turn  can reduce: the  efficiency  of ion  exchange   treatment.
These problems are often  overcome by adjusting pH so that the
desired  ionic  species are  present,   or  by  pretreating the
influent to remove complexing agents.  Pratreatment may also
be  required  if  the  influent to the  ion  exchange process
contains excessive suspended solids which  will  clog the bed
or foul  the resin.

Qzonatlon

     Ogonation is a  chemical oxidation process in which the
influent stream is contacted  with  ozone, which breaks refrac-
tory   (nonbiodegradable)   organic  compounds  into smaller,
treatable  or  nontoxic compounds.    Used   alone  or  in con-
junction with  ultraviolet radiation, it is  a highly effective
means  of treating dilute concentrations  of organics.   The
process  can achieve both effective disinfection and up to 99

                              C-6

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 percent  removal  of  certain  organic  compounds,   including
 pesticides,  chlorinated  hydrocarbons,  alcohols,  chlorinated
 aromatics,  and cyanides.

      The efficiency of contaminant  removal using ozonation  is
 dependent upon the retention time of the process reactor, the
 ozone dose  rate,  the  ultraviolet  light dcse  rate,  and t^e
 conLaminant  type   and loading.    Treatability studies are
 required prior  to  installation of ozonation  processes  to
 treat specific influent streams.

      ozonation is  currently used by only  a  few public-water
 supply systems,  primarily as a  disinfection  process.   It  is
 an  expensive  process which  is  readily  replaceable  with
 chlorination for  disinfection,  but  which  has  been gaining
 acceptance  for use in public water-supply systems because  it
 does not cause any byproduct trihalomethane formation.  Lack
 of use of ozonation in public water-supply treatment systems
 may be due to economic constraints and limited need for the
 technology.

 Disinfection and Fluoridatipr^

      Two  water-treatment  processes  that  are  universally
 available  are  chlorine   disinfection  and   fluoridation.
 Chlorine disinfection  is the  most  commonly  used  means  of
 destroying bacteria in public-water supplies.   Fluoridation
 of water supplies  is used to prevent dental health problems.
 The processes  do not  remove chemical contamination from the
 wastestream; they  serve instead as preventive measures  taken
 to control disease  and to maintain  public health.
C.2       Partial Bibliography of References Evaluating Water
          Treatment Technologies
American  Water Works  Association.   Research  Foundation and
     Keuringsinstituut  voor  Waterleidingartikelen   (Coopera-
     tive  Report).    "Occurrence  and Removal  of  Volatile
     Organic  Chemicals from  Drinking Water.1*    Denver,  CO.
     1983.

American  Water Works Association.   Water Quality Treatment.
     Denver, CO.  1971.

Argo,  D.6.,  "Control  of  Organic  Chemical Contaminants  in
     Drinking  Water.1*   U.S.  Environmental  Protection Agency
     Seminar, 1978.
                             c-7

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 Argo,  D.R.,  "Use of Lime clarification and -Reverse osmosis in
     Water Reclamation."    Journal  Water  Pollution Control
     federation 56:1238-1246.   December,  1984.

 Gulp,  R.L.,  C.M. Wesner,  and G.L.  Culp.   Handbook of Advanced
     Wastewater  Treatment.     2nd  Edition.    Van  Nostrand
     Reinhold,  New York,  New York.   1978.

 Environmental  Science and Engineering, Inc., Malcolm Pirnie,
     Inc.   "Fort  Lauderdale  Water  Quality  and   Treatment
     Study.1*    Prepared  for  the  City  of  Fort  Lauderdale,
     Florida.   1981.

 Ferguson,  T.L.  "Pollution  Control  Technology  for  Pesticide
     Formula tore and Packagers.**  Prepared for U.S. Environ-
     mental  Protection Agency, Office of Water and  Hazardous
     Material*  Programs.  January, 1975.  EPA-660/2-74-094.

 Glaze,  W.H.,  et  al.   "Oxidation  of Water Supply Refractory
     species  by  Ozone With Ultraviolet  Radiation."    U.S.
     Environmental  Protection  Agency.    EPA-570/9-74-020.
     1974.

 Gummerman,  R.C.,  R.L.  Culp,  and  S.P. Hansen.   "Estimating
     Water Treatment Costs.   Volume 1.   Summary.11  Prepared
     for  U.S.   Environmental   Protection Agency  Office  of
     Research  and  Development.   Cincinnati,  OH.   August,
     1972.  EOA-600/2-79-162a.

 Hoigne, J.,  and H. Bader.   "Ozone Requirements and  Oxidation
     Competition  Values  of  Various  Types  of  Water  for
     oxidation   of  Trace  Impurities.1*   U.S.  Environmental
     Protection Agency.   EPA-570/9-74-020.   Washington, D.c.
     1979.

Joyce,  M.    "Smyrna,  Delaware Solves  a  Water  Problem."
     Jpurpa.1 of Environmental  Healtft 42 (2): 72-74.  September/
     October 1979.

 Kim, N.K.,  and D.W.  Stone.   "Organic Chemicals and Drinking
     Water."  NYS Department of Health, Albany, N.Y. 1981.

Larson,  C.D.     "Tetrachloroethylene  Leached  from  Lined
     AsJpgsjtQtt  Cement Pipe into Drinking Water.*1   Journal of

     April 1983.

Mackison,  F.W.,  R.s.  Stricoff, and  L.J.  Partridge,  Jr., eds.
     "Occupational Health Guidelines  for Chemical  Hazards."
     U.S.  Department  of  Health and Human  Services and U.S.
     Department of Labor.   NIOSH/  OSHA.   Washington, D.c.
     January, 1981.   DHHS (NIOSH)  81-123.
                             C-8

-------
 Malarkey,  A.T.,  W.P. Lambert, J.w.  Hammond,  and P.J. Marks.
      "Installation  Restoration  General  Environmental  Tech-
      nology  Department.   Final Report.  Task 1.  Solvent and
      Heavy Metals Removal from Groundwater."  Roy F. Weston,
      Inc., West Chester,  PA.   Prepared  for  U.S.  Army Toxic
      and Hazardous Materials Agency.   January, 1983.

 McBride, K.K.   "Decontamination of Ground Water for Volatile
      Organic  Chemicals:    Select Studies  in Nev  Jersey"  in
      Aquifer Restoration  and Ground Water Rehabilitation — A
      Light at the  End of the Tunnel.   Proceedings  of  2nd
      National  Symposium  on Aquifer  Restoration  and Ground
      water .Monitoring.    David Nielsen,  ed.    Columbus,  OH.
      pp. 105-113.  May 26-28,  1982.

 Mccarty,   "Volatile   Organic   Contaminants  Removal  by  Air
      Stripping.H    Proceedings,   AWWA  Seminar,  99th  Annual
      National  AWWA  Conference,   San   Francisco,  CA.   June,
      1979.

Metcalf  and  Eddy,  Inc.    "Volatile   Organic  Removal:    Two
      Ground Water Supply Case Histories."   Presented at the
     Nev York Section AWWA.  1980.

Nabolsine,  Kohlman,   Ruggiero Engineers,   P.C.    "Technical
     Memorandum:  Well  Water  Supply  Testing  for the Removal
     of Organic  Contaminants."   Office  of the Mayor,  Glen
     Cover, New York.  1978.

O'Brien, R.P., et al.  "Trace Organics Removal from Contam-
     inated Ground  Waters  with  Granular  Activated Carbon."
     Presented  at   the   National   ACS  meeting,   Atlantic,
     Georgia.  1981.

Plimmes, J.R., ed.   Pesticide Chemistry in the 20th Century.
     ACS Symposium,   Division  of Pesticide Chemistry.   Nev
     York,  N.Y.  April, 1976.

Schvinn, D.E.,  D.F.   storrier, R.J.  Moore and  w.s.  carter.
      "PCB Removal by Carbon Adsorption.11    Pollution Engin-
     eering- 16m!2Q-21.   1984.

Shukle, R.J.   "Rocky Mountain Arsenal Ground-Water Reclama-
     tion  Program11  in Aquifer Restoration and  Ground Water
     p^ft^frf,! Itatiori—A  Light  at  the End  of  the  Tunnel.
     Proceedings  of 2nd National  symposium  on  Aquifer
     Restoration and Ground Water Monitoring.  David Nielsen,
     ed.  Columbus, OH.  May 26-28, 1982.  pp. 367-374.

Singley, J.E., et al.  "Use  of  Powered Activated Carbon for
     Removal  of Specific  organic Compounds."  Proceedings,

             AWWA Seminar,  99th  Annual AWWA Conference.  San
     Francisco, California.  June 1979.

                             C-9

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       APPENDIX D
SUPPLEMENTAL INFORMATION
  FOR CLASS I AND CLASS III
     ECONOMIC TESTS

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                          APPENDIX D

           SUPPLEMENTAL INFORMATION  FOR  CLASS  I AND
                   CLASS III ECONOMIC TESTS
     This   appendix  provides  background  material  on  the
economic  tests  of  irreplaceability  (for Class  I candidate
sites) and  untreatability  (for Class III  candidate sites) and
is  organized into  five  sections.   Section  D.I presents the
components  and types of water-supply  system costs.   Section
D.2 describes  general procedures for estimating the costs of
water-supply systems.   Sections D.3 and  D.4 emphasize cost-
estimation  procedures for  Class I  and  Class  III candidate
sites,  respectively,   and  present  illustrative  examples.
Section D.5 explains the derivation of the economic threshold
against which  water-supply costs are  compared and continues
the examples started in Sections  D.3  and D.4.   Section D.6
provides references used in developing Class I and Class III
economic tests.
D.I  Components and Types of Costs
     Water-supply  system costs can be  broken down into four
major components:

          1.   Acquisition.

          2.   Treatment.

          3.   Distribution and transmission.

          4.   Support services,


These 'cost  components are describsd in  more detail  in Section
D.I.I.     For  each  of  the  four  components,   costs  are
distributed  between two types of  costs:   (1) capital costs,
and  (2)  operation and maintenance (O&M) costs.   Furthermore,
capital  costs  and O&M costs  can  be combined to  derive total
annualized  costs.   Section D.I.2 describes the various types
of costs with an  emphasis on how to derive  total  annualized
costs.   The composition of water-supply-system costs by cost
component and type of cost is illustrated  in  Table  D-l.

                              D-l

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                                TABLE D-l

          COMPONENTS AND TYPES OF WATER SUPPLY SYSTEM COSTS A/
                                              Type  of  Coat
Cost  Component                Capital Costs                  O&M Costs
Acquisition              Land                          Labor
                          Right»-of-way                 Materials
                          Dams/reservoirs               Utilities
                          Well field                    Recurring
payments  for
                                                         water  rights

Treatment                Land                          Labor
                          Facilities                    Materials
                          Equipment                      Utilities
                                                        Parts and
inventory

Distribution and          Rights-of-way                 Labor
  Transmission            Distribution network           Materials
                          Pumping stations               Utilities

Support Services          Building                      Administration
a/  List of capital  and O&M cost  items  is provided for  illustrative
    purposes and  is  not meant  to  be  comprehensive.
                                   D-2

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 D.I.I  Cost Coaponenta
      Acquisition  costs  are   the   costs  of  producing  or
 acquiring vater and can be thought of as the costs of getting
 the  water  from  the source  to the  treatment point.   These
 costs include the capital and O&M costs of veils,  reservoirs,
 and  aqueducts, and payments to suppliers for purchased water.
 Treatment  costs include  the costs  of  treatment  plants  and
 equipment,  and  the  costs of chemicals that are added to the
 water.   Distribution  and transmission costs are the  costs of
 pumping  the water from  the  treatment  points  to  the service
 population  and  incorporate  the capital  and O&M costs of the
 piping  network.     Support   services   are  the costs  of
 administrative  and  customer services that are not  directly
 related to the physical process of delivering  water.

      Acquisition

      Acquisition   costs  depend  primarily   on   the
 characteristics of  the water sources for  the system and the
 distance from  the water  source  to  the  treatment  point.   At
 one  extreme,  these  costs may be  very  low  where  reliable
 natural  sources are  sufficient  to  meet  the needs of  the
 system.  For example,  the Culpepper, Virginia,  water utility
 acquired all of its water in 1976 from  a free-flowing stream
 that  fed directly into its treatment plant.   The  flow of the
 stream was  regulated  by  upstream reservoirs constructed to
 control flooding using Federal  funds.   Therefore  the utility
 had  .no  acquisition  costs.     Other  systems  benefit  from
 proximity to natural surface-water bodies, or  reliable stream
 or   river   sources.     In these  cases,   acquisition  costs
 typically  are   limited to  pumping  water from  the  natural
 source to the  treatment plant, although  payments for rights
 to use the water may be required.    In  general,  acquisition
 costs may be incurred  in the construction and maintenance of
 dams  and  reservoirs to collect  and  store surface water,  in
 the  development and   operation  of  well   fields  to  utilize
 ground-water sources,  and in pumping water from the  source to
 treatment plants.
     Treatment  costs depend  on  the  quality  of  the  water
source:     The  physical,  chemical,   and  bacteriological
characteristics  of  surface water can  vary on  a daily  and
seasonal  basis, depending on  rainfall,  temperature,  flow
rate, and the  character  of materials deposited over  the run-
off  area  or  discharged  upstream.    Daily  monitoring  and
adjustment  of  the  treatment   process   may  therefore   be
necessary.   On the  other hand,  for some New England water

                             D-3

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 controlled,  and  the  water may  undergo  natural  filtration
 during run-off  and  consequently require  no  treatment,  or
 merely a  small volume  of chemicals  added directly  to the
 reservoir.   Similarly, ground water may require only limited
 treatment.   Treatment costs typically  range  from  0  to 300
 dollars  per million gallons, but  in  extreme cases nay be as
 much  as  three times greater.   Costs  are likely to  increase,
 however,  in  the  full implementation of  the  Safe  Drinking
 Water Act,  as  amended  in  1986.

      Distribution  and  Transmission

      Distribution  *nd  transmission costs depend primarily on
 the distance from  creatment points to the service population,
 the   altitude  of   the population  served   relative  to  the
 treatment  points,  and  the density of the service population.
As the distance or height that water must  be  pumped  to the
 service population increases,  the unit costs of distribution
 and transmission increase.   Similarly,  increased dispersion
of the service population raises costs.   This component of
cost  is  a  substantial  fraction  of  total  costs  for  water-
 supply utilities and typically ranges between  $200  and $500
per million gallons supplied.

      Support Service*

      The  unit  costs  of  support services are  essentially
independent  of the physical  characteristics of  the system.
These costs are primarily admin.strative and customer service
costs . and  therefore depend primarily  on the characteristics
of the service population and the level of  service chosen by
the  utility;  however  they  are  typically about  $200  per
million gallons.
D.I.2  Types of Cost	


     capital costs are expenditures for  items  such as land,
buildings, and equipment that have a long economic life.  O&M
costs  ars  recurring  expenses  for  items  such  as  labor,
materials, and utilities.  Capital costs  and O&M costs can be
combine* to derive total annualized costs using the following
formula?

          TAG - f  CC  + CMC                             (1)


where: TAG ars total  annualized costs  ($  per year);

       f is the annualization factor;
       CC  are capital costs: and
       CMC  ars the  operation and  maintenance costs  ($ per
               ysar).

                             D-4

-------
 Because capital expenditures generally are for investments in
 capital  goods that  have  a relatively  long  life expectancy,
 capital costs are in units of dollars over many years.

     The  annual ization  .factor  is derived  to  obtain equal
 annual payments of capital costs  in constant dollars.  It can
 be derived using the following  formula:


          f - r / (1 - l/(l+r)n)                          (2)


 where:    r is the real discount  rate; and
          n is the life expectancy of the capital investment.


 This formula is the  same as the one used to obtain a total of
 n equal annual payments for a fixed mortgage in real dollars,
 where  r  is the real interest  rate  for the mortgage.   As  a
 first approximation, an annualization factor equal to  0.1 may
 be used.

     The choice of real discount  rate depends on the costs of
 available  financing  for the  water-supply system.   The U.S.
 Office of  Management and  Budget  (OMB)  recommends  that  a 10
 percent  rate  (i.e.,  r -  0.1)  be used to  discount  capital
 costs  in  the  analysis of  regulatory options.   Therefore,  a
 discount  rate  of  10  percent  may  be  used  to derive  the
 annualization factor.  Alternatively,  real interest rates on
 tax-exempt bonds  used  to finance  water projects can be used
 in the  analysis.    For a  real  discount rate  of 10 percent,
 Equation  (2)  suggests annualization  factor values  of 0.131
 and  0.106  for  Jife  expectancies n  of  15  and 30  years,
 respectively.   For a real discount rate of 5 percent (i.e., r
 • 0.05),  the annualization factor  is equal to 0.096 and 0.065
 for life expectancies of 15 and 30 years, respectively.
D.2  General Cost Estimation Procedures
     This  section  is  organized  in  three  subsections  as
follows:   Section 0.2.1 presents  a general  overview of the
cost-estimation techniques  and assumptions  for the  economic
tests.   Section  O.2.2 discusses three  general approaches to
cost  estimation,  and Section  0.2.3  shows how  to derive the
final cost estimate for either of the two economic tests used
in these Guidelines.
                             0-5

-------
 D.2.1  Overview of Cost Estimation
      The   economic  tests  of   irreplaceability   and
untreatability  are   intended  to  tost  whether total  water-
supply costs  after  replacement or treatment would  exceed  a
given economic  threshold.   For Class I  candidate  sites,  if
total costs   after   replacement  would exceed  the  economic
threshold,  then the  ground water underlying the site is class
I-irreplaceable.  For Class  III  candidate  sites,   if  total
costs after treatment would exceed the  economic  threshold,
then  the  ground  water underlying the  site  is  Class  III-
untreatable.   The economic tests  therefore can be  written as
follows:
          TAG  >  TACtfc                                   (3)
where TAG is the total annual ized costs for the system
      (S/yr/hh) ; and

      TACth is  th* threshold cost  for the economic  tests
      (§/yr/hh).


Cost estimates  in  Equation  (3)  are  in units  of  dollars  per
year per household.   For unit conversions, the classifier may
assume 100,000  gallons per year per household.

     Total annual ized costs  for a water-supply system can be
calculated as the  sun of total annualized costs over the four
cost components identified in Section D.I:


          TAC - TACa + TACt + TAC
-------
 where:    TACa   are   the   total   annualized  costs   for  the
               acquisition component;
          f  is the annualization factor;
          cca are capital costs of acquisition;  and
          OMCa   are  operation   and maintenance   costs   of
               acquisition.
 D.2.2  Methods for Estimating Costs
     There are  several  approaches  to  estimating the  costs  of
water-supply systems/ including the following:


     1.   Engineering cost estimates,  i.e.,  estimates derived
          assuming   certain   design,  construction,  and
          operation specifications;

     2.   Existing  system  costs,   i.e.,  costs  currently
          incurred by specific water-supply  systems;  and

     3.   Typical   system  costs,   i.e.,  costs  typically
          incurred by water-supply systems in the nation.


Other  approaches  include combinations of the  three  methods
mentioned above.   Regardless of the cost  estimation  approach
used, the matrix-form worksheet in Table D-2  can be  used  to
estimate the cost  of  a  water-supply system.    This worksheet
breaks  down  water-supply  system  costs  by cost  component
(e.g., acquisition) and type of cost (e.g.,  capital costs).

Engineering Cost Estimates

     Engineering  cost  estimates  begin  with  a   thorough
inventory of  items or activities resulting  in costs.   Table
D-l  illustrates  a  sample of these cost  items  for each cost
component broken down between capital  costs  and OSM costs.

     Except  for  a  site-specific  analysis of  engineering
costs, cost estimates can  be  derived  using  engineering-based
cost equations  for the various  capital  and 0&M cost items.
These   cost  equations  are   available  in  the  published
literature  for  a  number  of  possible  water-supply  system
designs.    For  example,   EPAs  Gulp   et  al.   report  (1978)
presents  capital  and O&M  cost  curves and cost  tables  for
construction.   Another  useful  source  of  data for acquisition
costs is the NWWA  Nationwide Water Well  Drilling Cost Survey
(NWWA, 1979).   The results of  this survey  are summarized  in
the  form of tables  giving drilling  and casing costs as a
function of the well  diameter,  hydrogeologic conditions,  and

                             D-7

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                             TABLE D-2

                 WATER SUPPLY SYSTEM COST WORKSHEET
                                                           Total
                           	Type of Cost	     Annualized
     Cost Component        Capital Costs   O4M Costs       Costs
Acquisition


Treatment


Distribution and
    Transaission

Support Services


     TOTAL
                               0-8

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 other factors.   Although  this  survey dates back to 1979, it
 provides  useful  information on costs which must be escalated
 to  account  for inflation.

      Zn addition,  several reports have been published by EPA
 on  the costs of water treatment,  including the following:

      e    Estimating Water Treatment Costs. Gummerman, Gulp,
          and Hansen, EPA  600/2-79-162a.

      •    Treatabilitv   Manual.  Technologies  for  the
          Control  Removal of Pollutants.  EPA 600/2-82-
          001C

      e    Estimation of Small  System  Water Treatment Costs.
          EPA 600/2-84-184a.

When  using published cost  curves, it  is important to identify
the system  components included  in the cost curve.  Table 0-3
lists  the  system  components  typically  required  for  each
treatment technology.   Table D-4 indicates engineering-based
annual ized  cost  estimates for  typical  treatment components
for four typical plant  sizes.

      Cost data provided in  the sources mentioned previously
must  be  updated  to account  for inflation  and geographical
variations  (e.g.,  in  costs  of  labor  and  energy).    The
Engineering News Record publishes cost indices for such items
as  materials,  energy,  and  labor.    Also,  updated  cost
assessments will  likely be  available from EPA  or  the water
utility industry under  the public water-supply provisions of
the Safe Drinking Water Act.         •.-?. ••    :   ..- -;^

      If engineering cost  estimates are used for a given cost
component, then estimates  of capital costs and O&M costs must
be  entered  into  the worksheet  for  this component.   Total
annual ized  costs  for this component then  are calculated as
the   sum  of  O&M  costs   and   annualized  capital  costs  as
indicated in Equation (5) .

                     Costs
     As  an alternative  to  engineering cost  estimates, the
costs  of an  existing water-supply  system can  be estimated
rather  accurately  if  detailed  accounts  («.g«,  financial
statements)  are  available  from  the  water  utility  that
owns/operates the system.   Not all  water-supply systems may
be willing to share detailed  cost  data with the classifier.
In the absence  of such detailed  accounts,  it is possible to
use  rates charged  by  the utility  as  an  indicator  of the
system costs.   However, rates charged and true system  costs
may differ for a number of  reasons.
                             D-9

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                            TABLE D-3

      TYPICAL COMPONENTS OP SELECTED TREATMENT TECHNOLOGIES
Aeration/Air  stripping

     Aeration tower
     In-plant pumping
Filtration
     Granular media  filtration
       beds
     Granular media
     Backwash pumping
     Washwater sewage .basin
Activated Carbon

     Carbon columns
     Backwash pumping
     Washwater  surge basin
Ion Exchange
     Pressure ion exchange
       system
Chemical Precipitation

     Line  feed  system
     contact clarifier
     Sludge pumping
     Sludge drying beds
     Sludge hauling
Flotation
     Dissolved air flotation
     Sludge pumping
     Sludge drying beds
     Sludge hauling
Desalination
     Reverse osmosis
     In-plant pumping
Ozonation

     Ozonation system
Ancillary Operations

     Administrative
     RMMflster pumping
     Polished water pumping
     Clearwell storage
                             D-10

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                   TABLE D-4

          ANNUALIZED COSTS OF TYPICAL
   TREATMENT COMPONENTS FOR FOUR PLANT SIZES
Treatment
Component
Aeration/
User Peculation Size
500
$16,500
2,500
$20,700
5,000
$28,000
25, COO
$70,200
Air Stripping
Activated
Carbon
Chemical
$18,600

$35,200
$27,000

$51,500
$33,900

$62,700
$113,900

$127,700
Precipitation
Desalination
Flotation
Filtration
Ion Exchange
ozonation
Ancillary
$43,900
$30,100
$56,200
$10,100
$6,000
$25,900
$109,500
$37,300
$61,400
$26,400
$7,000
$24,000
$171,500
$48,900
$69,100
$38,900
$9,300
$46,200
$595,600
$109,800
$107,700
$74,800
$19,200
$110,900
All figures in  1982 dollars.
                   D-ll

-------
     The  utility may not  set  rate*  on  the basis of economic
coats  of  supply  or the utility may not  face the true economic
costs.   The utility may  charge  different rates to different
types  of users  in such a way that  one type of  user (e.g.,
industrial  users)  implicitly subsidizes other types of users
(e.g., households).  Also; some  systems may receive subsidies
from the  Federal government  or other public agencies; in such
a sitution  the rates charged by  the system would be less than
true economic costs.

     Typical System Costs

     Finally,  it  may  also be possible to determine typical
costs   based  on   survey  data   drawn   from  water  systems
throughout  the  country-   Typical  system costs  ar« defined
here as  the median (i.e., 50th percentile) cost of all water
supply systems  of equivalent  size in the nation.  Estimates
of typical  water-supply system costs are provided in Table D-
5 for  each  of seven user population size ranges.

     If   typical   estimates  are used  for  a  given  cost
component,  then  total  annualized   costs  can  be  entered
directly   for   this  cost   component.    Typically,  total
annualized  costs for a given component  are equal to a certain
fraction  of the total  annualized costs of  the whole system
(i.e., SUB  over all components of total annualized costs for
each component).   Table  D-6  indicates this  fraction of the
total  system cost-by-cost  component and  system  size range.
For  example,  the  typical cost  of acquisition  for  a water-
supply system  serving a population of 5,000 persons is equal
to roughly  $40 per household  (i.e., the  product of $180 per
household from  Table 0-5 multiplied by the 22 percent value
from .Table  D-6) .
D.2.3  Final Cost Estimate
     The  total  annualized  costs  for  a  given  water-supply
system  are  reported  in  the  lower  right  cell  of the  cost
estimation worksheet in Table  D-2.  As indicated earlier, the
total  annual ized  costs   for the  system can  be derived  by
sunning op total annualized costs for  each of the four cost
components  (Equation  4).    Section  D.2.2  explained  several
possible  methods for estimating total  annualized  costs for
each component.   As discussed in the following two sections,
the choice  of cost estimation method depends on the economic
test considered.
                             D-12

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                          TABLE D-5

              TYPICAL WATER SUPPLY SYSTEM COSTS
          User Population     Median Annual Cost
               Size            ($/household)
          101-500                   240
          1,001-3,300               190
          3,301-10,000              180
          10,001-25,000             130
          25,001-50,000             12u
          50,001-500,000            100
          500,001+                   70
     Total  annualized  costs,  i.e., annualized  capital costs
(debt  service  of  capital  expenditures)  plus  O&M  costs.
Depreciation costs  are not included.   Costs are  rounded to
the nearest ten dollars.
     Source:    Data   collected  by  the  Research  Triangle
Institute  (Inmennan,  1987)  and analyzed by  Cadmus,  Inc. and
ICF Incorporated.
                             D-13

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                          TABLE D-6
              COMPONENT COSTS AS A PERCENTAGE OF
                TOTAL WATER SUPPLY SYSTEM COSTS
                            User  Population Size
          Coat Component    300-75,000    75,001+

          Acquisition         22%          19%
          Treatment           18%          13%
          Delivery            43%          38%
          Service             17%          30%
     Total annualized cost* of a component as a percentage of
total annualized costs for the system.

     Source:  ACT Systems, Inc.,  1979.
                             D-14

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 D.3       COST  ESTIMATION  FOR  THE  CLASS  I  -  ECONOMIC
           IRREPLACEABILITY TEST
      Given  the   general  procedures  described  above  for
 estimating the cost of a water-supply system, the procedures
 used for  a  specific Class  I  or Class  III classification
 should   reflect  the  intent  and  design  of  the  economic
 irreplaceability  test or the economic  untreatability test,
 respectively.   This section provides guidance for estimating
 costs   in  keeping  with   specific   Class  I,   economic
 irreplaceability  requirements  while Section 0.4 explains the
 cost estimation procedure for  Class III.
D.3.1   Class  I  Cost  Estimating  Procedure
     As   noted  in   the  discussion  of   the  economic
irreplaceability  test  for Class  I  sites  (Chapter  4) ,  the
purpose  of this  test is  to  determine whether  the economic
burden of  replacing an existing ground-water supply would be
unreasonable.   If the burden  of the replacement costs would
be  unreasonable,  then  the  ground  water  is  Class  I  —
economically irreplaceable.

     In order to apply this test, the annualized total system
cost after the affected component(s) of  the existing system
has  been  replaced  must  be  calculated.    The  replacement
process may  range  from simply sinking a new well (or tapping
a surface-water source)  to creating  an entirely new public-
supply  system  for  households  previously  served by private
wells.    Therefore,   the   classifier  should first  establish
which components will remain unaffected and which  will need
replacement  in  the  event  that  the  ground  water  in  the
Classification  Review Area  becomes unusable.     Once  this
division  is  established,  the  classifier can  compile  the
various cost estimates to  yield  a total system cost.

     in  general,  the classifier  should  rely  on  readily
available; cost information and use best professional judgment
to  determine which  data   sources  are most  appropriate when
making-a cost estimate.  The classifier should note, however,
that  the  Agency  believes  that  some  data  sources   (e.g.,
existing  system  costs)   are  more  accurate  and  therefore
preferable to other data sources.
                             D-15

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     For  system components that will not require replacement
 (e.g.,  the  distribution  network  for  an existing  system),
 current annual costs for those components represent the most
 accurate  source  of  data  and  should be  preferred.    If  the
 water-supply  system(s)  in question will not make these costs
 available,  then  engineering costs  as  described  in section
 O.2.2  are probably  the  next best source  of  accurate costs.
 Costs  for the relevant components of similarly sized existing
 systems  in the same geographic region as the  ground water
 under  consideration Bay  also  provide  reasonably  accurate
 information.    If   the  total  costs  for the  system(s)  in
 question  are  available  but not broken down into component
 costs, these  aggregate cpsts could be disaggregated using the
 component proportions provided  in Table D-6.

     As a final  source  of data, the typical cost estimates
 for  specific  components  can be developed by combining  the
 information  in Tables 0-5  and D-6.   In  using these typical
 costs, however, the  classifier  should verify that the cost of
 the  component  at a  particular site  is  unlikely  to differ
 significantly from the  median cost across the country of the
 system component.   Classifiers should  be aware that if  the
 typical cost  values  presented  in Table 0-5,  which represent
 national  median values, are  used in all cases, then the total
 system  cost   estimate   will   never  exceed the  ninetieth
 percentile threshold values  demonstrating irreplaceability.

     For  system  components that  will require  replacement,
 costs that are  drawn directly or imputed from existing system
 components  very  similar  to  the  anticipated   replacement
 components  should be preferred.    If  these costs  are  not
 available  or  are not disaggregated among  cost  components,
 then engineering  costs are preferable.  Likewise, costs drawn
 or  imputed  from existing  system  components of  comparable
 systems in the  same  geographic  region may be useful.

     If only the  total costs of the system (s) in question are
available, then the  classifier may be able  to  disaggregate
total costs using the proportional values presented in Table
D-6.  In doing  so, the classifier should recognize that these
proportions  represent entire   components  (e.g.,   the entire
acquisition system).  If only a part of the component (e.g.,
 a singles, vail) is being  replaced,  therefore, the classifier
 should correct  the  calculations  accordingly  to  avoid
 overestisfefeion  of costs.

     Finally,  if  no  other  sources of  data are  available and
 the classifier  can verify that  the replaced component (s) will
 not  differ   significantly  in  cost  from  the  typical
 component (s) throughout the  country, then the typical cost of
 the replaced  component(s) can  be  estimated  by  combining the
data provided  in  Tables 0-5  and D-6»
                             D-16

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      One* the classifier  has compiled the  appropriate cost
 estimate* for  both unaffected  and  replacement  components,
 these costs  should be converted  into annual household costs
 using the  methodology  presented  in  Section 0.2.1.    The
 following  section  presents   a  hypothetical  example  to
 illustrate this process.
 D.3.2  Hypothetical Example of Class I Cost Estimation
     This  section provides  an  Illustrative example  of cost
estimation procedures  for a Class  I  candidate  site.   Within
the Classification Review Area,  there are 500 private wells,
each  serving a  single household and one public  well  field
serving  a public-water  system  of  2,475  persons.   Given  an
average of 2.75 persons per household, there are estimated to
be 3,850  persons using water from  within the Classification
Review Area  (i.e., 1,375 private well users plus 2,475 public
system users).   The  classifier  determines that, in the event
that  the ground water  becomes unusable,  the public  water
system   will  develop  a   new  well   field  outside  the
Classification Review  Area and  the private well  users will
require connection to the public-water system.

     The annualized  per-household cost after  replacement  of
the ground  water is estimated  as  the  sum of  the four cost
components.   First,  total  annualized  acquisition  cost  is
estimated at $142 baaed  on the technical  specifications  of
the new well field  and the distance  from the  new well field
to the  existing treatment  plant.   Second,  total  annualized
treatment costs  are  assumed to remain constant at $118 on a
per-household  basis  because  the  water  quality  of  the
replacement  is comparable  to ground-water quality within the
Classification Review  Area and  the addition of  the  private
well  users  does   not  increase  the   total  system  size
significantly.   Third, total  annualized costs for delivery
are increased to $248 to  reflect extension of the existing
delivery  system  to  the  private well users.   Finally, per-
household support service  costs  are  assumed  to  remain the
same at  $92.  In this example, total costs are estimated at
$600 per household per year.
                             D-17

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D.4       COST  ESTIMATING   FOR  THE  CLASS   III   ECONOMIC
          UNTREATABILITY TEST
     As with the Class I economic irreplaceability test,  the
general  procedures  for  estimating water-system  costs,   as
presented  above,  should reflect the intent and design of  the
economic  untreatability  test  when  performing a  Class  III
determination.  This section provides guidance for estimating
costs   in   keeping  with   specific  Class  III  economic
untreatability requirements.
D.4.1	Class  III  Cost Estimating Procedure	


     A«  noted in  the discussion of  the Class  III  economic
untreatability in  Chapter 6, the purpose of this test  is  to
determine whether the costs of treating a ground-water source
would  sake the  total system cost  of a hypothetical  water-
supply  system unreasonably  expensive.   If the  total  system
cost would   exceed  the applicable  economic threshold  due  to
excessive treatment  costs, then the ground water would not  be
considered a potential source of drinking water.

     In  order   to   apply  this  test,   the  annualized per
household cost  of a hypothetical ground-water supply  system
must be  estimated.   Because the cost estimate is based on a
hypothetical  system, the total cost  estimate should include
costs  for  each system  component,  including  acquisition,
treatment, delivery, and services.

     In  order to ensure  that the test focuses  on  treatment
costs  rather than   on  costs for  the remaining components,
typical cost values  derived from the information presented  in
Tables D-5 and D-6 are provided as a source of default values
for  acquisition,   delivery,   and  services.      In   some
circumstances, the classifier may chose to use cost estimates
for nontraatment components that are based on costs typical
of similsjrlysized systems  in  the same geographic  region  as
th« groundt water under review  if these costs are clearly and
substantially different from the national median costs.

     In  all  cases/  the  cost  estimate  derived  for  the
treatment  component  of  the hypothetical  system  should  be
based  strictly   on  site-specific  treatment costs and  njo£  on
default  or  typical  national costs.    Moreover, in applying
this test,  the  classifier should ensure that  the treatment
csaponant  cost   used  is  based  on  the  least  expensive,
technically  feasible   treatment  train.     While  the

                             D-18

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 identification of  the  least expensive treatment train may not
 be possible  until  all  feasible  train*  are  reviewed,  some
 trains  may  be disregarded  immediately.    For example,  any
 treatment  train  (e.g., aeration and flotation) that includes
 other technically  effective treatment trains  (e.g., aeration)
 clearly will  be less cost  effective and nay be disregarded.

     In estimating the cost o£ a feasible treatment train, a
 detailed  site-specific engineering  cost  estimate  should  be
 compiled  if possible.     If  such  detailed   costs  are
 unavailable,  then  the  classifier can compute costs using the
 methods given in Section  D.2.2, which  presents  a discussion
 of engineering cost sources,  typical components of potential
 treatment  trains,   and annualized  costs  for  those treatment
 trains.    Site-specific  treatment  costs  may  be  calculated,
 therefore,   by  applying  the  engineering  cost-estimation
 information  presented  in  Section  D.2.2 to the site-specific
 treatment  trains  available   for  the site  under  review  and
 choosing the  least  expensive  treatment train.  This treatment
 cost, prepared  as  an  annualized per household  cost,  should
 then  be   added  to  the  cost  estimates  for  acquisition,
 delivery,  and services  in order  to produce  a total  system
 cost estimate.

     The  following  section   illustrates  how  a  hypothetical
 water-supply  system cost  may be estimated using typical cost
 estimates  for acquisition, delivery, and services and site-
 specific engineering cost  estimates for treatment.
D.4.2	Hypothetical Example of Class III Cost Estimation
     This  hypothetical example  is based  on  a ground-water
source  that  is   contaminated  by  trichloroethylene,
tetrachloroethylene,   carbon  tetrachlor ide,   cadmium,   and
selenium  at  levels that  are  above relevant water-quality
standards.    The  ground  water,  therefore,  would  require
treatment before  it  could be  usable for  drinking purposes.
Based on information provided by the U.S.  Geological Survey,
it is estimated that the  aquifer could sustain a daily yield
of 440,000 gallons.   Assuming  a daily per capita  need  of
roughly 100 gallons,   the  hypothetical user population  that
could be  supplied by  this  well would be  4,400 persons,  or,
assuming 2.75 persons per household, 1,600 households.

     Using this hypothetical  population  size,  the annualized
household  cost   for   a  water  system  that  would  include
treatment  technologies  necessary  to  treat  the  water  to
relevant standards  could be  calculated using the following
steps.


                            D-19

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      First,  the  default values  for acquisition, delivery, and
service can be calculated using the information presented in
Table*  D-5  and  D-6.   According  to  Table  D-5,  the  median
annual  household cost  for a  total water-supply system serving
a  population of 4,400 people would be $180.   Likewise,  Table
0-6  indicates that,  for a system of 4,400 people, acquisition
is typically 22  percent of the  total system cost; delivery is
typically  43  percent;  and service is  typically 17 percent.
Based on these  values,   therefore, the  default  values  would
equal:


            Acquisition - $39.60      (180 x .22),

                     Delivery   •  $77.40      (180 x .43),

                     Service     -  $30.60      (180 x .17).


      Second,  the reference  technology  test  identified  three
possible  treatment  trains that  could adequately  treat the
ground  water to  appropriate  standards.    These  treatment
trains  include the following:


          1.   Air stripping and chemical precipitation.

          2.   Chemical precipitation and filtration.

          3.   Chemical precipitation,  filtration,  and
               desalination.


Because  the  third  treatment   train  would  add  a  treatment
component to  the  second treatment train that is not necessary
to meet relevant standards,  the third treatment train may be
disregarded.   The) costs of the  remaining two treatment trains
may  be  estimated  using  the  engineering  cost  information
provided in Table D-4.   According to  Table  D-4,  the cost of
air  stripping for a system size  of 4,400  (rounding  off to
5,000)   is   $28,000.      Likewise,   the  cost  of  chemical
precipitation is  $62,700 while  the  cost  of filtration is
$69,100*   Inflating these figures from 1982 to 1986 dollars
(i.e.,  that year  used  to  calculate  the ninetieth percentile
threshold  function)  using  the  Construction  Cost  Producer
Price Index  (i.e.,  an 8.1 percent  increase)  yields $30,300,
$67,800,  and $74,700  respectively.    The  first  treatment
train,•  therefore,   would  cost  $98,100  while  the  second
treatment train would  cost $142,500.  The first train is  thus
the  least  expensive.  Because these costs are for the entire
system,  the  cost  of $98,100 should  be divided  by 1,600 in
order to yield the cost per  household  of about $61.  Finally,
this  treatment  cost  can be   added  to  the  default  values
                             D-20

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 calculated above  to yield an annualized total system cost per
 household  of  $209.
 D.5   Derivation  and Calculation of Economic Thresholds	


      Economic  thresholds are used  for  both the  Class  I and
 Class III  economic tests.  For the economic irreplaceability
 test  (Class I) ,  the  threshold  is used to  determine whether
 the cost of a  replacement water-supply system would impose an
 economically  unreasonable  burden  on the  user  population,
 hence making  the  existing  source irreplaceable.    For the
 economic untreatability test (Class I±I),   the threshold is
 used  to determine  whether the cost of  a water-supply system
 to a  hypothetical  user population would be made unreasonably
 burdensome  by  the need to  treat the ground-water  source in
 question, hence  making that ground-water source economically
 untrcatable.   In both  cases, the Agency  has determined that
 if  the  annualized   total   costs of   the  replacement  or
 hypothetical  water-supply  systems would  exceed the  costs
 faced by  90 percent of community water-supply system users,
 then  the   replacement  or   hypothetical   systems  would  be
 economically  unreasonable.    The thresholds  used  for  both
 tests,  therefore,  are the ninetieth percentile per household
 costs  for  community  water-supply systems.    This  section
 briefly describes the derivation  of the cost function used to
 calculate  threshold  values  and  then  presents  the  actual
 methodology for  making calculations.     Two examples  of the
 use of  the thresholds are also presented.
D.5.1     Derivation of Economic Thresholds
     As  described   in  section  D.2.2,   water-supply  rates
charged  to  residential  users  often do not  reflect  true
economic costs.   The costs used  to develop  threshold values
for these  Guidelines,  therefore, are  community water-supply
system costs  and not  water  rates.   Using data collected by
the  Research  Triangle  Institute  for  the  EPA  Office  of
Drinking  Water  report  "Final  Descriptive  Summary:    1986
Survey   of  Community  Water   Systems"  (Zmmerman,  1987),
ninetieth  percentile  water-system  costs  were  calculated.
Becauser the  thresholds  are  to be  applied  as  a  function of
system size (i.e., user population), for reasons noted in the
economic irreplaceability  test discussion of Chapter 4,  the
ninetieth  percentile  values  were  derived  for each  of  the
twelve size categories employed in  the 6DW  report.  Finally,
based on  the  assumption  that the  average household water
usage is 100,000  gallons per year,  the data  from the report,

                             D-21

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 given  as cants per  1,000  gallons,  war* converted to dollars
 per household  per year.

     In  order  to Bake  the  twelve observations  (i.e.,  the
 ninetieth  pereentile  cost  for each  of  the twelve  system
 sizes)  from the OOW survey  usable  for a continuous range of
 system sizes,  a linear regression  was performed with system
 size as the independent variable  and cost per  household as
 the dependent  variable.   The purpose  of a linear regression
 analysis is to Mathematically define the function which best
 describes  the  relationship  between   two  variables.    After
 adjusting   the  scale  of  systea   size  with  a  logarithmic
 transformation, the  following equation was developed:
   THRESHOLD-  (-200.255  X  LOG (SIZE))  -I-  1248.727

               R2 -  .712
               Standard error of Y estimate » 179.44
               N • 12  (i.e., the  number of systsm sizs
                         categories)

where,    THRESHOLD • threshold cost in dollars per household
                         per year, and
               SIZE - user population  (individuals).


Figure D-l presents this function graphically, along with the
twelve observations used to define the function.


     As  the  analysis results indicate,  the equation appears
to approximate  the relationship between cost and system size
fairly well,  explaining roughly 71 percent of the variation
in costs around different  systea sizes.  Note, however, that
the standard error of the estimate, which can be taken as the
range above or below the estimate within which the true value
will  fall soae  67 percent of  the time,  is  somewhat large.
The   classifier  should   use   best  professional  judgment,
therefor*, when making a  determination  of irreplaceability
based on these threshold values;  especially if  the  cost of
the  replacement  water systea  falls  very  close  to  the
threshold value.
D.5.2  Methodology for Calculating Econoaic Thresholds	


     In  order  to  calculate  the  ninetieth   pereentile
thresholds  for  either   the  economic  irreplaceability  or
untreatability  tests,   the   classifier  should  take  the
following three steps.


                             D-22

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                                              Figure D-l
O
                            Ninetieth Percentile Economic Thresholds by System Size
                                  200.000
400.000
600.000
aoc.ooo
1.000.000
                                                       System Size
                                                   (User Population Served)
                       SOURCE: ICF  Incorporated Analysis of  Data  Collected by Immerman  (1987)
                       DATE:   1988

-------
      First,  the classifier  should determine  the  number of
 individuals  served  by  the  water  system.     For  Class  I
 candidate  sites,  this  number  should  have  been   estimated
 already for  the substantial population analysis.   For Class
 III situations,  this number should be  based on the maximum
 sustained yield  of the aquifer  in question  as explained in
 Chapter 6.   If the available size data  is for  households
 only,  the classifier should convert households to individuals
 by assuming an average of 2.75 persons per household.

     Second,  the classifier should take the  logarithm (base
 10)  value of the user population  size.  This transformation
 is necessary in order to manipulate the size  variable in the
 proper  scale.    Most  hand  calculators  have  function  keys
 allowing the  easy log transformation of numbers.

     Finally,  the classifier should solve  the equation given
 above  by multiplying the log  value of size  by -200.255 and
 adding this value to 1248.272.   The solution  of  this  equation
 is the  ninetieth percentile  economic threshold for a  user
 population  the  size of the  system under review.

     As an  illustration  of   this  methodology, consider  a
 replacement water-supply  system  which would serve  a  user
 population  of 4,500  persons  and which is under review for a
 Class  I determination.  The cost  function  for estimating the
 ninetieth percentile economic  infeasibility threshold should
 be applied  as follows:


          THRESHOLD  -   (-200.255 X LOG(4,500)J  + 1248.728

                              -  (-200.255 X 3.653)  +  1248.728

                              -  -731.532 *  1248.728

                         -  $ 517.20.


     If the  annualized total cost  per  household of  the
 replacement water-supply systea would  be greater than roughly
 $517,  then  the coat  of that systea would be  an unreasonable
 economic: burden on the  user population and the current
 ground-water  supply could be considered irreplaceable.
D.5.3  Illustrative Applications of Econoalc Thresholds	


     This section  extends  the examples  related to Class I and
Class  III  procedures  provided  in  Sections  Do3.2  and D.4.2,
respectively, to demonstrate the use of economic thresholds.


                             D-24

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      Claaa I Example

      Section  0.3.2   presented   an   example  of  a  Class  I
 candidate  sits.    In  the  example,  a  system  with a  user
 population  of 3,850  parsons  was determined  to face a par-
 household cost of  $600  in the event that the ground water in
 the Classification Review Area became unusable.  .By using the
 equation  described   in  Section  D.5.2  above, - an  economic
 threshold of  $530 . for  a  system of this  size is calculated.
 Because  $600  exceeds  $530,   the  ground  water  cannot  be
 replaced  at  reasonable  cost.    Accordingly,   the  site  is
 classified as Class I - irreplaceable.

      Class III Example

      Section D.4.2 illustrated the estimation of total system
 costs  that  reflected treatment of  contaminated ground  water
 at  a  Class  III  candidate  site.    Based on the  maximum
 sustainable  yield   of  the  aquifer   in  question,   the
hypothetical water  system was determined  to  have a  size of
4,400 persons.   Moreover, per household costs were estimated
at $209.  For a system of this  size, the economic threshold
is estimated at $519.  The total costs of $209 fall below the
threshold of $519; the site is not Class III and is instead a
Class IIB - potential source of drinking water.
                             D-25

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D.6     APPENDIX 0 REFERENCES
ACT,  Syataaa,  Inc.  1979.   Voluaaa  I *  II,   Managing Small
  Water  Syataaa:   A Coat  Study Praparad for U.S. EPA, watar
  Supply Raaaarch  Diviaion.  Hunicipal Environmental Raaaarch
  Laba,  XERL.


Gulp,  R.L.,  6.X.  Weaner,  and 6.L. Gulp,  197t.   Handbook of
  Advancad  Haatavatar Treatment.  2nd Edition.  Van Noatrand
  Rainhold, Nav York, Nav  York.


Immerman,  Fradriek  W.,   1987.    Final  Daacriptiva Summary:
  1986 Survay  of  Community Watar Systems).   Praparad by tha
  Raaaareh Triangla  Inatituta,  Raaaarch Triangla Park, North
  Carolina, for tha Offica of Drinking Watar, USEPA.


National Watar  Wall  Association,  1979.   Watar Wall Drilling
  Coat Survay.  NWWA, Worthington, Ohio.


Traatability Manual. Taehnolocriaa for tha Contra?. Ram oval of
  Pollutants. EPA  600/2-82-001C.


Eatimatien of Small  Syataa Watar Traataant Coal^a. EPA 600/2-
  84-184a.
                             D-26

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o  o
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