PB94-964210
                                 EPA/ROD/R06-94/087
                                 February 1995
EPA  Superfund
       Record of Decision:

       Double Eagle Refinery Site
       (O.U. 2), Oklahoma City, OK
       4/19/1994

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          RECORD OF DECISION
         DOUBLE EAGLE REFINERY SITE
         GROUNDWATER OPERABLE UNIT
          OKLAHOMA CITY, OKLAHOMA
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                 APRIL 1994

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        CONCURRENCE DOCUMENTATION

                     FOR THE

 DOUBLE EAGLE GROUND WATER OPERABLE UNIT
              RECORD OF DECISION
                   Lis4 Price
        Peer RevieV ^Committee' Chairper_son
                 Phj&ip H. Allen
          Site Remedial Project Manager
                 "Mel McFarland
            Office of Regional Counsel
                  Regional Counsel
Barbara Greenfield, •tariUMMf Chief#  Superfund Branch
         Office of4»Real$nal Counsel   6C-W
                !arT lldlund,  Chief
         Superfund Programs Branch   6H-S
            Button - Acting Regional Counsel
         Office of Regional  Counsel  6C
            Allyn M. nDavis ,  Director
     Hazardous Waste Management Division  6H

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                            DECLARATION
                    DOUBLE EAGLE REFINERY SITE
                     GROUNDWATER OPERABLE UNIT

                       Statutory Preference for Treatment
                           as a Principal Element
                                is not
                      Met and Five-Year Review is Required
 SITE  NAME  AND LOCATION

 Double  Eagle  Refinery Site
 Oklahoma City,  Oklahoma
STATEMENT OF  BASIS AND PURPOSE

This  decision document presents the  selected remedial action  for
the  Double Eagle Refinery  Site  (DER site) ,  in  Oklahoma City,
Oklahoma, for the Ground Water Operable Unit.  The Source  Control
Operable Unit Record of Decision  (ROD) for this site was completed
and signed on September 28, 1992.  The remedy for the DER site  was
chosen in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA),  as amended by  the
Superfund Amendments and Reauthorization Act of  1986 (SARA), and,
to the  extent practicable, the National Contingency  Plan  (NCP).
This decision is based on the Administrative  Record for this site.

The State of  Oklahoma  concurs  with the selected  remedy.
ASSESSMENT OF THE SITE

Actual or  threatened releases  of hazardous substances  from this
site, if not addressed by implementing the response action selected
in this Record of Decision, may  present an imminent and substantial
endangerment to public health,  welfare,  or the environment.

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DESCRIPTION OF THE SELECTED REMEDY

This Record of Decision (ROD)  addresses  the contamination in the
groundwater.  Principal threat wastes include "pools" of dense non-
aqueous phase liquids  (DNAPLs)  submerged beneath the ground water
or  in  fractured bedrock.   Although  there  was  no free  phase
contamination  noted  during drilling  operations   at  the  site,
certain chemicals were detected  that are contaminants associated
with DNAPLs.  This Ground Water Operable Unit (GOU) addresses the
principal  threat at the site  by monitoring the ground  water to
ensure that the  contaminant levels are reduced with time due to
natural attenuation, once the surface contamination is addressed,
so that the surface contamination will no longer provide a source
of contamination to the ground water.

Past oil production activities have rendered the upper ground water
zone non-useable  (Class III aquifer) due  to the  presence of high
Total Dissolved Solids. The data also suggests the possibility of
an offsite source of contamination.  Therefore,  implementation of
a ground  water recovery and treatment system is  not considered
appropriate  at  tftis  time.    Plowever,  a  potential exists  for
contaminants to  migrate vertically  to  a  potential  drinking water
aquifer.  Therefore, monitoring to ensure that migration does not
occur is appropriate.

This action is the second and final operable unit for the DER site.
This second operable unit is also referred to as the "Ground Water
Operable Unit" (GOU).  The  first operable unit for the  DER site,
termed the Source Control  Operable Unit  (SCOU),   addressed  the
source of  contamination both  onsite and  offsite,  which included
surface  sludges,  contaminated surface water  and   sediment,  and
contaminated soil and debris.

The major components of the selected remedy include:

     •    Installation of additional ground water monitoring wells.

     •    Establishment of  a  routine monitoring and maintenance
          program  for ground  water sampling and modeling,  to
          evaluate contaminant level reductions, upon removal of
          the surface contaminant source materials.

     •    To  the  extent that  site  access  is  available,  new
          monitoring wells  will  be placed to determine whether
          there is an off site source of contamination.

     •    A five-year  review to analyze the  data  obtained  and
          computer modeling to  determine  if  contaminant  level
          reductions are  being  achieved  as  expected,   once  the
          surface source of contamination is stabilized.
                      •
     •    Contingency  action  that  could  be  implemented if  the
          contaminant concentrations increase or the contaminant
          plume migrates horizontally  or vertically to  a usable
          water supply.

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STATUTORY DETERMINATIONS

The  selected  remedy  is  protective  of  human health  and the
environment, complies with Federal and State requirements that are
legally  applicable or relevant  and appropriate to the  remedial
action,  and is cost-effective.   This remedy  utilizes  permanent
solutions to the maximum extent practicable  for the conditions  at
the site.  However, treatment of  the hazardous  constituents in the
ground water was found to be inpracticable.

Because this remedy will result in hazardous substances  remaining
on  site  above health-based levels,  a  review will  be  conducted
within five years after commencement of remedial action  to  ensure
that the remedy continues to provide adequate protection of  public
health, welfare, and the environment.
 ani N.' Saginaw                              Date
  jional Administrator
Region 6

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                         DECISION SUMMARY
                              FOR THE
                    DOUBLE EAGLE REFINERY SITE
                    GROUNDWATER OPERABLE UNIT
                      OKLAHOMA CITY,  OKLAHOMA
I.  SITE NAME. LOCATION. AND DESCRIPTION

The Double Eagle Refinery Site ("DER site", or "the site")  occupies
the Southeast  Quarter (SE 1/4) of Section 35, Township 12  North,
Range  3 West,  Indian Meridian, Oklahoma  City,  Oklahoma County,
Oklahoma.  Located at 1900 NE First Street, the site is bounded to
the north by the Union Pacific Railroad tracks (also referred to as
the ATSF-Santa Fe railroad),  and to the west and south by  vacant
lots zoned for industrial land use.  Martin Luther King Boulevard
lies on the east side of the site as an overpass to the  railroad
tracks.  The DER site  is fenced and extends over approximately 12
acres.

The Fourth Street Refinery Superfund Site  ("FSR site") lies about
500 feet  northeast of the DER site,  just north  of the  railroad
tracks  and just east  of  Martin Luther King (MLK)  Boulevard.   The
DER and FSR sites  are separated  only by the MLK overpass,  and
contain very similar waste material since both sites recycled used
oils.    Due  to  the  fact  that these  sites  are  in  such   close
proximity, and migration of contaminants in certain cases  overlap,
this Record of Decision  (ROD)  will make reference to the  FSR site
as necessary. The FSR site was addressed in a separate ROD.  Figure
1 provides'a general location map.  Figure 2 provides a schematic
of both the DER and FSR Superfund sites,  and shows the  location of
each site  in relation to  the  other.   Figure 3 provides a site
layout for the DER site.

Although industrial areas immediately surround the site,  the land
use within a 1 mile radius of the DER site  is mixed industrial  and
residential.  One residence is located to the north of the  railroad
tracks and to the east of Martin Luther King Boulevard, adjacent to
the FSR site.   A small neighborhood  is located about 1/4 mile to
the north,  on the other side  of the industrial complex adjacent to
the railroad tracks which border the  site. Four  schools  (Douglas
High School, Dunbar School,  Bath School,  and Edwards School)  are
located within a 1 mile radius of the  site.  Recreational  areas
close  to the  site include the Douglas  Community  Center,  Douglas
Community Park,  and Washington Park.  Drug Recovery, Inc.  is  the
only medical facility located within a 1 mile radius of the site.

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                                                      OKLAHOMA
                                     I  FOURTH STREET SITE
               NORTHEAST FDURW STOEET
NOT TO SCALE
                                          Figure  1   Site 'Location Map

                                        DOUBLE EAGLE AND FOURTH STREET
                                                SUPESFUNO SITES.
                                            OKLAHOMA CITY. OKLAHOMA
                                                                           R.UOR DANIEL

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The  DER site has contributed to offsite contamination at  offsite
areas  called the "Radio  Towet  area" and  "Parcel  H".   The Radio
Tower  area is  located just south  of the Double  Eagle  site  and
Parcel  H is located just south of the Fourth  Street site.   The
North  Canadian  River  is  located just  south  of  Interstate  35,
approximately  one  half  mile  south  of  the  site.    Although no
endangered species have been identified in these areas,  wildlife in
the  area  includes migratory  fowl  and  small mammals.


II. SITE HISTORY AND ENFORCEMENT ACTIVITIES

Site History

The  Double  Eagle Refinery collected,  stored, and re-refined used
oils and distributed the recycled product.  The refinery was active
as early  as 1929 with  historical aerial photographs available as
early  as  1941.    Generally,  early refining  was conducted  on the
western portion of the  site and expanded toward the eastern  portion
as the operations increased.

The  DER recycled approximately 500,000 to 600,000 gallons  of used
motor oil per month into  finished lubricating oil.  The recycling
process consisted of the  addition of  sulfuric acid, settling, and
filtration with bleaching  clays via a filter press.  This  process
generated approximately 80,000  gallons  of oily sludge per month.
Sludges were initially sent to an off-site disposal facility, now
the  Hardage Criner Superfund Site located in Criner,  Oklahoma.
Later, sludges were disposed  of in onsite impoundments and a sludge
lagoon until the late 1960's to early 1970's.

Onsite  and  offsite visual   inspections,  by  the  Environmental
Protection Agency (EPA) Field Investigations Team in May of 1985,
indicated  that  a  preliminary  sampling  inspection  should  be
conducted.   An  Expanded  Site Inspection was  conducted by  EPA in
1987-88  which  confirmed   that  the  site  should  be  ranked  for
inclusion on the National  Priorities  List (NPL).  . In March 1989,
the  DER site was added to the NPL, pursuant to Section 105 of the
Comprehensive Environmental Response, Compensation, and Liability
Act  (CERCLA), 42 U.S.C. Section 9605, as amended.

The  Remedial Investigation/Feasibility  Study   (RI/FS)  for  the
Groundwater Operable Unit  (GOU)  was  initiated in June 1992  for the
DER site; and the RI and FS were both  completed  in July 1993.  Due
to the close proximity of the DER and FSR sites,  and due  to the
similar types of  wastes present at both  sites,  EPA assigned one
contractor to conduct the  RI/FS projects concurrently.  Therefore,
distinguishable   characteristics of   each  site  could be  easily
identified,  and  mobilization and remedial alternative development
efforts would not be duplicated for the overall study area.

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 In  conjunction with the site  investigations and related  studies
 performed  by  the  EPA,  the  U.S.  Fish   and  Wildlife  Service
 (Department  of  Interior  -DOI)  conducted   a  Preliminary  Natural
 Resource Survey (PNRS)  for the  DER site.  Technical information was
 gathered  from  site visits, National Wetland Inventory  maps, EPA
 analytical  data, and  personal communications  with the Oklahoma
 Department  of  Wildlife Conservation  (ODWC) and  EPA.    The  study
 revealed that  the  DER  site  is  upgradient of a  small "oxbow  lake"
 (created  by damming natural  drainage)  which lies  south  of the
 Parcel H area.  The site is also upgradient of  the  North Canadian
 River.  The  varied habitat  adjacent to the Parcel H ponds,  oxbow
 lake, and the  North Canadian River is capable of supporting good
 populations  of common urban fish and wildlife species.   According
 to  the  PNRS report, a dead opossum  and a ring-billed gull was
 recovered from the  concrete vat  (basin), and a dead opossum were
 noted in one of  the lagoons on site during the site visit by the
 DOI.

 As  a result  of the site investigation performed by the  DOI  (U.S.
 Fish  and Wildlife) the  EPA  prepared  an  "Action Memo"  dated
 September 13, 1993,  which was signed by the Director, Environmental
 Services Division.  The Action Memo authorizes the EPA  to expend
 funds to install protective netting over an approximate 2.5 acre
 sludge lagoon to  preclude access by wildlife, and provide a  barrier
 to  the  highly toxic  and  acidic  contamination  present  at the
 surface.  The PRPs have  been offered the opportunity to conduct the
 planned action at the site.

EPA Enforcement Activities

 In  December  1988 EPA  issued"  an Unilateral Administrative  Order
 (UAO) to the site owner, requesting that the north side of the site
 be  fenced to prevent people and animals from coming into direct
 contact with the hazardous  substances.  The owner complied with the
AO and completed the fencing in February  1989, which mitigated the
 immediate risk to public health.

 Prior to initiating the RI/FS for the Source Control Operable Unit
 (SCOU)  in Hay  1990,   EPA  conducted  a search  for  Potentially
Responsible Parties (PRPs).  EPA sent Special Notice letters  to 17
 PRP's  identified   in   the  search.     The  letters  included  a
 notification of potential liability under  Section 107  of CERCLA.
The letters also included a demand  for  reimbursement of EPA's past
 costs as well  as an offer  affording the PRPs  an opportunity to
perform the  RI/FS.  None  of  the  parties  receiving the Special
Notice made  a good  faith offer to  conduct  the RI/FS, nor did any
parties  offer to reimburse the EPA for the past costs incurred.

 EPA  conducted  the  RI/FS  for   the  SCOU  as  a Fund  lead project.
 Simultaneously with the performance of  the RI/FS,  EPA proceeded to
pursue leads regarding other unidentified PRPs.  In October  1992,
 several  previously undiscovered boxes of  manifests were located at
the Oklahoma State  Department  of Health  (OSDH)  archives, now the

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 Oklahoma  Department  of  Environmental  Quality   (ODEQ),  which
 contained records of shipments  of  waste oil and other  hazardous
 wastes to the DER facility.   These manifests were from  the time
 period of 1980-1982.  From these records 46 Special  Notice letters
 were issued on December 16,  1992.  A PRP group  formed in January
 1993,  and the EPA met with the group on February 11, 1993.  At this
 meeting the EPA provided the PRPs the liability information linking
 the PRPs to the site and past cost documentation for funds expended
 by the EPA.   A group of 22 PRPs made a good  faith  offer  to "cash
 out" on March  31,  1993.   EPA  anticipates future  negotiations with
 respect to the SCOU.

 EPA conducted  the RI/FS for  the GOU as a Fund lead project also;
 however,  the  newly  identified  PRP's were  sent  General Notice
 letters on February  9,  1993, affording them the  opportunity to
 participate  in  the  GOU  Remedial  Design/Remedial  Action,  and
 informing them of GOU RI/FS activities.

 Negotiations with the EPA and the PRPs, pertaining  to all aspects
 of enforcement activities are ongoing.

 State Enforcement Activities

 During 1977 and 1978  numerous  inspections conducted by the Oklahoma
 Water  Resources Board (OWRB)  indicated that un-permitted  releases
 of hazardous waste occurred  both onsite and  offsite.  Subsequent
 inspections  conducted  by OWRB  revealed that  the  Double Eagle
 facility continued to discharge  hazardous substances  in violation
 of the facility permit.  As a  result of the unpermitted releases of
 hazardous waste, OWRB referred this case  to  their General  Counsel,
 seeking a Cease and  Desist Order on September 14, 1985.

 III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
           /
 This decision  document  presents  the selected remedial action for
 the GOU for the DER  Superfund site,  in  Oklahoma City,  Oklahoma.
 This action is chosen in accoidance with  CERCLA,  as  amended by the
 Superfund Amendments and Reauthorization Act (SARA)  and, to the *
 extent practicable,  the National Contingency Plan  (NCP), 40 CFR
 Part  300.     The decision   for  this   site  is  based  on  the
 administrative record.  An index for the administrative record is
 included as Attachment A to this document.

 The public   participation  requirements   of  CERCLA,    sections
 113 (k) (2) (B) (i-v)  and 117, were met  during the  remedy selection
process.   The Remedial  Investigation and  the  Feasibility Study
 reports  and the Proposed Plan were released  on August  5, 1993, and
were all made  available to the public in both the  administrative
record  and  information  repositories.     The  repositories  are
maintained at  the  Ralph Ellison  Branch  Library,  the ODEQ Central
Office in Oklahoma City, Oklahoma, and the EPA Region 6 Office in
Dallas,  Texas.   The notice of  availability for these documents was
published  in The Black Chroniclef on August 5, 1993.

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 The  EPA and ODEQ  held an Open House in Oklahoma City on February
 18,  1993, to explain the Superfund process and to notify the public
 that RI activities for the GOU had begun.  The RI fieldwork for the
 GOU  was discussed and general  information about the site as well as
 new  developments pertaining to the SCOU were provided to the public
 by the  EPA.

 A  30-day public comment  period was held from  August 5,  1993 to
 September 4, 1993.  On August 16, 1993,  the EPA  received a request
 for  a  thirty-day  extension in accordance with  40  CFR §  300.430,
 from one of the PRP representatives  on behalf  of the participating
 PRPs.    On  August  27,  1993,  the'  EPA responded  to  the  PRP
 representative  granting  the  30-day  extension  request,  which
 extended the public comment period until October 7, 1993  (due to a
 holiday  weekend within this period).  Two  commenters  submitted
 written comments during the public comment period.

 A public meeting was held in Oklahoma City on  August  12, 1993.  At
 this meeting, representatives from the EPA presented information on
 the  RI, Risk Assessment and FS.  EPA and ODE'Q answered questions
 about the site,  the remedial alternatives under  consideration, and
 the  Proposed Plan  of Action.  Responses to the  comments received at
 this meeting, as well as the comments received in writing during
 the  public  comment  period,  are included in the  Responsiveness
 Summary, which is included in this ROD as Attachment B.
IV. SCOPE AND ROLE OF OPERABLE UNIT 2 WITHIN THE SITE STRATEGY

During the RI/FS project for the  SCOU for the DER site, the issues
related  to  ground water beneath the  site were acknowledged  as
complex in comparison to those obvious with respect to the surface
contamination, consisting  of the sludges  and  tar mats,  and the
contaminated  soil,  sediment  and surface water.    During  the
investigations required  for ranking the site for inclusion on the
NPL,  the  resulting reports  indicated that  there was a continuous
shale layer acting as an  "aquitard" beneath the  site, since this is
generally  the  regional  geology.    However,  during  the  field
investigations conducted as part  of the RI  for the SCOU, the shale
layer was not present beneath the site.  Shallow and deep alluvial
wells were installed around the perimeter of both the DER and FSR
sites, but the determination of vertical and lateral migration of
ground water contaminants required further study.  Therefore, the
site was separated into two Operable Units to address the surface
contamination and  the ground  water  problems individually.   The
impact  of the  migration  of  contaminants  in  ground water  and
possibly to the North Canadian River is addressed in this ROD for
Operable Unit 2 (Ground water Operable  Unit - GOU).

Principal threat wastes are those source materials considered to be
highly toxic  or highly  mobile that generally cannot  be  reliably
contained or would present a  significant risk  to human health  or
the environment should exposure  occur.  The  principal threats  at

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 the DER site pertaining to the surface contamination are the acidic
 sludges  within the sludge  lagoon  and  contaminated ponds.   These
 were addressed in the SCOU ROD which was signed  on  September 28,
 1992.

 Low-level threat  wastes are those  source materials that generally
 can be reliably contained and that  would present only a low risk in
 the event of a release.  The low-level threats at the site are the
 contaminated  surface  soils and tar  matrices.   These  low-level
 threat wastes  were also addressed in the SCOU ROD.   The Remedial
 Design for the SCOU was initiated  on June 21,  1993.

 Principal threat  wastes pertaining to ground water are  defined as
 "pools"  of dense non-aqueous  phase  liquids  (DNAPLs)   submerged
 beneath  ground water or  in fractured  bedrock.   The  contaminated
 ground water in the immediate area of the site is classified as a
 Class  III aquifer  by  EPA,   and the  ODEQ  agrees  with  this
 classification." Class III aquifers are considered unusable  due to
 the presence of Total Dissolved Solids (TDS)  in  excess  of  10,000
 parts per million (ppm).  The average and maximum concentrations of
 TDS in  the alluvial  aquifer  were 2,460  ppm   and  13,100  ppm,
 respectively;  and in the  upper portion  of the Garber-Wellington
 (bedrock)  aquifer  the  TDS  were  34,680  ppm  and  110,000  ppa,
 respectively,  for  the wells  installed  at  the  DER site.    The
 remedial  objectives of  the GOU  are to minimize potential exposure
 by  direct contact (which includes  accidental ingestion  and  dermal
 contact)  or inhalation,  and to  reduce the potential  for migration
 of  contaminants into  the surface waters  and useable ground  water
 supplies.

 V. SUMMARY OF SITE CHARACTERISTICS

 General Overview
           s
 The DER site and offsite^areas (Parcel  H and the Radio Tower area)
 are not  located in the 100 year floodplain.  Generally,  the  local
 surface  drainage  flows  to  the  south and  east of the  DER  site.
 Prior to  construction of Interstate  35, the North Canadian  River
 meandered  through the -adjacent  FSR site.   During construction  of
 the highway, the river was diverted to  the south side of 1-35,  and
 is  now located approximately one half-mile to the  south  of the DER
 site.

 Ponds on the DER  site and portions of the Parcel  H Area  appear  on
 the National Wetlands  Inventory Haps (NWI)  (U.S. Dept.  of Interior,
 Fish  and  Wildlife Service,  1989).    These  maps are   based  on
 interpretation  of  aeprial  photographs  and  not  on   actual  site
 surveys..   The  NWI maps  are prepared by review of the aerial
photographs and do not distinguish between  pristine  ponds and
 sludge lagoons covered with surface water, or other types of waste
water  treatment   ponds.    Migratory  fowl   have   no  way   of
discriminating  between  clean  and  contaminated   surface waters,
therefore, the  DER site  is  considered a  wetland area  until the

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remedial action for the SCOU is complete.   Once the SCOU remedy  is
implemented, no ponds will remain, and the site will essentially  be
left as a dry field.  Therefore, the DER site will  no longer be a
wetland after the Remedial Action.

The North Canadian  River is located just south of  Interstate 35,
approximately  one-half  mile south  of the site.   Although  no
endangered species have been identified for these areas, wildlife
in the area includes migratory fowl and small mammals.

Nine alluvial  monitoring wells  were  installed at  the  DER site.
Five of the alluvial monitoring wells were installed in the shallow
alluvium with the top  of 5 foot screens placed at  depths varying
from  10 to  19 feet.    The  remaining  four alluvial wells were
installed with the top of five foot screens placed between 28 to  34
feet below  ground surface.  Six "bedrock" monitoring wells were
installed around the perimeter of both the  DER  and  FSR  sites with
the top of 10 feet screens placed about 5  feet  into the  top  of the
Garber sandstone.  The top of the Garber sandstone  varies from  25
to  57   feet below  ground  surface across the DER  site.    The
monitoring  well locations  are  shown  on  Figure  4.    The  terms
"bedrock" or "upper bedrock" used  in this ROD shall refer to the
uppermost portion of the  Garber-Wellington  aquifer, and the terms
may be used interchangeably.

General Geology and Hydrogeology Characterization

The DER  site is situated on Quaternary  alluvial  deposits  which
represent recent  deposition by  the nearby North Canadian River.
The floodplain  deposits typically consist  of  unconsolidated and
interfingering  lenses  of  sand,  silt,  clay,  and gravel.   These
alluvial  sediments   are  predicted  to   have  relatively  high
permeabilities and  porosities.   The alluvium  in Oklahoma County
ranges in thickness from several inches to 90 feet below ground
surface along the river basin.

Directly below the alluvial deposits are the Garber  and  Wellington
formations.  Regionally, these bedrock  formations  (i.e.,  lithified
strata below  the alluvial channel  fill)  have  a  gentle westward
homoclinal dip of 30 to 40 feet per mile.  However,  the DER site  is
located on  the northeast flank of the  Oklahoma city  oil  field
surface  anticline.    Beneath the  site,  the   dip  of the  Garber
sandstone  is  to  the east-northeast,  which is opposite of  the
regional dip.  The  bedrock formation beneath  the DER site begins
approximately   25   to   57  feet   below   the   ground   surface.
Collectively, the  Garber-Wellington consists  of  massive,  cross-
bedded  sandstones  irregularly   interbedded with  siltstones  and
shales.  The  "red bed"  sandstones  and shales  of  the  Garber and
Wellington  Formations  are  similar  in  lithology and  conform
gradationally.  Therefore, these formations are commonly mapped  as
a single lithologic unit  and classified as a  single aquifer (the
Garber-Wellington aquifer). Cross section  locations  and  a Geologic
Cross Section are shown on Figures 5 and 6, respectively.

                                10

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The Garber-Wellington aquifer constitutes the most important source
of ground water in Oklahoma County.  Wells drilled into the water
bearing  zone  may penetrate as much  as 200 to  300  feet of water
bearing  sandstone.   Artesian conditions exist  below  200  feet in
areas in which the aquifer is overlain by the Hennessey Group.  The
depths of municipal, institutional, and industrial wells screened
in the Garber-Wellington range from 100 to approximately 1,000 feet
in Oklahoma County.  Yields of wells  less than 250 feet deep range
from  5  to  115  gallons  per  minute  (gpm)  and  average 35  gpm.
Reported yields of wells more than 250 feet deep range from 70 to
475 gpm  and average 240  gpm.    The  principal  hydrologic factor
controlling the development of the aquifer for fresh water supply
is the presence of high Total Dissolved Solids  (TDS) in the ground
water.   Shallow ground water (water encountered  at  a depth less
than 100 feet) in the area is not used as a  water supply due to TDS
levels in excess of 10,000 ppm.  The high TDS content in the ground
water is attributed  to past oil  and  gas production activities in
the area.

No drinking water wells currently exist within a 1 mile radius of
the site.   Residents  and industries  in  the area utilize water
obtained  from  reservoirs surrounding the city.   Results  from
sampling the  alluvial  ground water beneath the DER site revealed
that the TDS ranged  from 310 ppm to 13,100 ppm with an average of
about  2,500  ppm  for the  nine  alluvial  wells  at the  DER site.
Results from sampling the upper bedrock monitoring wells  (installed
with a 10  feet screen  placed approximately 5 feet below  top of
Garber sandstone) indicate TDS from 5,200 ppm to 110,000 ppm with
an  average of about  35,000 ppm  for  the  three bedrock  wells
installed around the perimeter of the DER site (BMW #1,  #2 and #6).
Therefore, this zone is considered a Class III aquifer due to the
high TDS, which would prohibit use of the shallow ground water for
domestic purposes.   Class III  aquifers are  characterized  by TDS
concentrations greater than 10,000 parts per million (ppm) .  Figure
7 shows the degree of contamination with respect to the TDS, based
on data  obtained  from  sampling  from  the  upper bedrock monitoring
wells.


Site Hydrogeologic  Conditions


The site is  underlain  by unconsolidated  deposits  of alluvium
material consisting of about 1 to 3 feet of topsoil, beneath which
is a mixture of mostly sandy material  mixed with silt and clayey
gravel.  The thickness of the alluvium varies from about 25 to 57
feet below the ground surface.  Underlying these alluvial deposits
is the bedrock material.   The uppermost  bedrock formation is the
Garber Sandstone.
                                14

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15

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The  Hennessey Group formation, predominantly reddish-brown shale
containing  some layers of  siltstone  and fine-grained sandstone,
overlies the  Garber-Wellington Formation in parts of the region.
However, this shale layer was  not  encountered above the Garber-
Wellington  aquifer  (as  originally anticipated)  in  the deeper
borings drilled at both the DER and  FSR sites in March of 1992,
indicating that the shale has been completely removed by erosion in
the area of the site prior to the deposition of the alluvium by  the
North  Canadian River system.   This shale material was originally
believed to have been a continuous layer beneath the site, which
acted  as an  "aquitard" that separated the upper and lower ground
water  aquifers.  However, the more recent studies revealed that no
Hennessey shale  is present beneath the site,  concluding that there
is no aquitard between the upper alluvial material and the bedrock.
Therefore,   the  upper   and   lower  water   bearing  zones   are
hydraulically connected.  Due to the absence of the Hennessey Shale
beneath the  site,  this Operable Unit was initiated to assess  the
vertical migration and potential impact of site contaminants on  the
deeper Garber-Wellington  aquifer.

In addition,  the lateral migration and  potential impact of site
contaminants in  the ground water on the  nearby Canadian River  has
been investigated, and the results presented herein.  Although  the
Garber-Wellington  aquifer is  the most important source of ground
water  in the Oklahoma  City  area,  the City  of Oklahoma  City
currently receives its public water supply from lakes in the area.

During drilling  operations   at  the  site,  ground  water   was
encountered at varying depths that  ranged from 7 to  20 feet below
ground surface.  Subsequent ground water  monitoring indicates that
the ground water levels range from about 7  to 17 feet below  the
ground surface.     The  ground  water  levels  were  determined
periodically and exhibited  moderate seasonal fluctuations due to
seasonal variations in rainfall.
Nature and Extent of Contamination

The  Groundwater RI/FS  was  focused to  provide  information for
discrete areas of concern and subsequent migration pathways.
From all the chemicals  detected in the ground water at the  site,
certain chemicals  were  identified as potential  Contaminants of
Concern (COC) based on the COCs from the SCOU.  The RI/FS revealed
that numerous contaminants similar to those found in the sludges,
sediments,  and  soils onsite, were detected in the  ground  water
sampled from the alluvial and upper bedrock monitoring wells.  The
contaminants  found were  primarily  organic  chemicals  and  heavy
metals related to the  refinery  process.   The most commonly  found
organic  chemicals  were  Chlorinated  Hydrocarbons  and  Benzene
compounds.   Lead was the primary metal  contaminant found in ground
water  samples taken  during  the  investigation.    The COCs are
discussed in detail in Section VI - Summary of Site Risks.
                                16

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 Other   chemicals   detected  .  consisted   of    Dichloroethane,
 Trichloroethane,  and  Dichlorobenzene.     Some  or  all  of  the
 contaminants identified in this section are "hazardous substances"
 as defined in Section 101(14) of CERCLA, 42 U.S.C.  § 9601(14),  and
 40 C.F.R. § 302.4.  Although there was no free phase contamination
 noted  during   drilling   operations,   these  chlorinated  benzene
 compounds are contaminants associated with Dense Non-Aqueous Phase
 Liquids (DNAPLs), and suggest the presence of DNAPLS  at  the site.

 A summary of the  ground water sampling data is presented in Table
 1.   The maximum,  minimum, and mean concentrations  of  contaminants
 were calculated for all  samples collected at all screen  depths.
 This data represents the contamination encountered in the alluvial
 and  upper portion  of the  Garber-Wellington  (bedrock)   aquifer.
 Ground  water  samples taken at the  site  also   contained high
 concentrations  of Total  Dissolved  Solids  (TDS).  All three  upper
 bedrock monitoring  wells have  shown  concentrations  equal to or
 greater than 10,000 ppm,  indicating that the  upper  portion of  the
 Garber-Wellington (bedrock) aquifer in the vicinity of the site is
 a  Class  III  aquifer   according  to  the   EPA  Ground   Water
 Classification  System.

 Samples were collected from both the  alluvial  and upper portion of
 the  Garber Wellington (bedrock)  aquifers,  to identify the level of
 contamination in the ground water.  Data obtained from the bedrock
 monitoring wells represented the current level of contamination at
 a depth (60  feet) of the assumed  future  residential well.  Data
 obtained from the upper aquifer were  used  in ground  water modeling
 to predict the concentration in the lower aquifer at a future date
 and  to  determine  exposure  point  concentrations  for  the risk
 calculations.

 The  results of  the  ground water samples were used in a model to
 predict worst-case  contamination levels in an imaginary  drinking
 water well located  in  the top of the  bedrock aquifer at the  DER
 site boundary.   The  model was also used to  predict the impact that
 a contaminant plume in the alluvial aquifer may have on the North
 Canadian River. In  developing the model,  it was assumed that the
 regional ground water gradient is to the southeast.  Modeling was
 also performed  to estimate the extent of contamination in the upper
 portion of the  Garber-Wellington (bedrock)  aquifer.  These results
were used to estimate the risk  from  potential use of the bedrock
 aquifer as a drinking water supply.

Contaminant Migration in the Alluvial Aquifer

The  water  level measurements  taken  in  conjunction with  the  RI
reveal  that a downward ground water  gradient  exists at the site;
however, any mounding effect, due to  standing water on the ponds.
and  lagoon,  beneath the DER   site   is  considered  negligible.
Regionally,  the  ground  water in the alluvium flows  towards the
North Canadian River (southeast).  The average ground water flow
rate for the DER site was estimated to be 20 ft/year for the


                               17

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                                  Table  1
          Monitoring Well Statistical  Data Summary
 PARAMETER
                                      NO. OF
                                     DETECTS
       MAXIMUM
        (UG/U
        MINIMUM
        (UG/l)
                                MEAN
        (UQJD
Ahiinlnutn
                                          23/36
         67900 JO
           152 JO
                                 1080238
Atmnwoy
            14.70
                       1470
                                    1435
Amnfc
                                          25/36
           149.00
                                                                  52)
                        1484
Barium
                                          3936
                                          14/30
          1790.00
             4 JO
           116X0
            1JO
           53180
                         1.13
Cadmium
                                           1/38
             1.30
                        1JO
                         1.65
Ctfckim
                                          36/36
       1190000.00
                     77400 JO
                     29292222
Chroinhin
17)36
71.90
                        2 JO
            1143
Cobrt
                                          1506
            29.40
            5.70
             638
 GOBBflf
 *^*rt^^_
 8/38
22J60
                         7.35
Iran
31/36
                                                   55600.00
                                                               1710 M
                      16295/16
                                          27/36
            73120
            1.70
            1404
                                          36/36
        375000.00
                     12700 JO
                     77936.11
                                          36/36
          5350 JO
           310X0
          165942
metal
11/86
                                                     54.10
            7.40
            13J7
                                          86/36
         24200 JC
           630JC
          941040
                                                     12JO
                        2.10
                         2J2
                                          35/36
       3130000JO
                      120JO
                     395531.11
                                          30/36
           160X0
                        3JO
                        43JB3
ano
2S86
                                                    214 JO
                        7^40
                        8408
VaytCMortda
 «M
27JO

                                          13/38
            12.00
                                                                  1JO
                                          1(V36
           380JO
            4 JO
            2341
CvbonOtaAto
             »JO
            »M
1.1
 1/86
 2JO
2JU
1.1
 7/86
12JO
2JO
13-00110
           29JO
            3J»
             SJB
                                                     36JO
                       22JO
                        8JBB
                                          2/38
                        7JO
1.1.1-TOtiJoiD^htlM
 1/B6
 4JO
                        4JB
                                                     1100
                                                                 2JB
                                                                              4JZ
                                          11AJ8
          240X0
            2J>
                                   12.19
                                          2O6
           88X0
                                          1/B6
                                          5/38
          200X0
           10X9
                                          406
          170X0
                        HUB
                                          886
                        IXO
                                                      OJO
                        OJO
                                                      8X0
                        txo
                                                                              8.14
                                          8/96
           87X0
            1X0
                                          1/B8
            8X0
                                          1/B8
            2X0
            2X0

                                                      7X0
                        2X0
                        5.11
                                                     35X0
                                                      OJD
                                          1M
                                    5.H
                                          3/36
                       &BO
                                                      1X0
                                          1/n
            oxo
            0/40
                                         12/96
            2X0
            OJ90
                                                                             4.11
                                          108
                                                                             5.18
                                         14/38
          200X0
            050
                                          1/18
                       0X0
                                                                             4J7
                                          1g7
            0.11
                       0.11
                                                                             OJN
                                          2B7
                                          18
            0X7
            0X8

-------
 contaminant  transport model.    The major  source areas  for the
 alluvial  aquifer were  assumed  to  occur  at areas  where sludge
 material was placed in the past, and standing water was observed.
 Dispersion  represents  an  important  mechanism  for  contaminant
 migration, and  results  in the spreading of the contaminant plume
 and also causes the reduction of maximum concentrations.   Figure 8
 shows the predicted benzene plume in the alluvial  aquifer  based on
 the most conservative values used for dispersivity.  Based on the
 results of the model, contaminant concentrations will decrease over
 time.  Maximum  Contaminant Levels for the contaminants of concern
 should be attained in 30  to over 150 years.  This is discussed in
 more detail in  Section VI - Summary of Site Risks (Risk Summary).
 It is important to note  that contaminant mass loading rates were
 estimated to provide an estimation of contaminant concentrations at
 the  current  well locations.    Although  the  modelling  results
 successfully approximate  the  maximum concentrations of COCs from
 four  sampling  events,  seasonal and analytical  variability was
 observed.

 Contaminant Migration in  the Bedrock Aquifer

 The water  level measurements  from  the  upper  bedrock monitoring
 wells indicate that the flow direction in the upper portion of the
 Garber-Wellington aquifer is generally to the south.  The average
 flow  rate  for  the  upper bedrock  aquifer was  assumed to be  10
 ft/year for the  contaminant transport model.  The major source area
 was  assumed to be  the  contamination  present  in  the   alluvial
 aquifer, since the surface contamination was assumed to have been
 removed.   Dispersivity  values  for the  bedrock modelling  were
 considered to be the same  as the alluvial aquifer of  50 and 20 feet
 for the  longitudinal  and transverse  dispersivity,  respectively.
 Figure 9 shows the predicted current benzene plume in the bedrock
 aquifer based on the aforementioned assumptions.  Table 2 shows a
 comparison  of  model  predicted contaminant concentrations  and
 analytical 'results  for the  samples from the  bedrock  monitoring
wells.  Also, Figure  10  is provided to  show the  current benzene
plume at 20 ppm, with the respective level of TDS contamination.

 Impact on the North Canadian River

The receptor point for the alluvial aquifer was assumed to be the
North Canadian  River  (River).    Figure 11  shows the  predicted
benzene plume,  when  the  peak  concentration is predicted in the
alluvial aquifer  just before discharging  to the North  Canadian
River.  For predicting the impact on the North Canadian River, the
observed contamination in the monitoring wells  was  attributed  to
the DER site.

Table 4  shows the maximum concentration predicted by the model  in
the alluvial  aquifer just  before the ground water is discharged to
the river.   The background  data in Table  4 are the  results  of
sampling directly from the river, and indicates that mixing of
                               19

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 ground water  with   the  surface  water  in  the  river  reduces
 contaminant  concentrations   significantly.     This  results   in
 concentrations  significantly  below  the ambient  water  quality
 criteria for the river  as shown in Table 5.
YL SUMMARY OF SITE RISKS

Human Health Risks

As part of the Remedial Investigation for the 6OU at the DER site,
a  quantitative risk  assessment  was performed to  estimate human
health  risks  posed by  the migration of  contaminants  within the
groundwater,  and  lateral  migration  of  contaminants  to  surface
waters from the DER site.  The methods used in the development of
the  risk  assessment  are  based  on the  following EPA  guidance
documents: Risk Assessment Guidance for Superfund.  Vol. I:  Human
Health  Evaluation Manual  (Part  A).  1989. also  known  as "RAGS".
Exposure Factors  Handbook (1989bl. Risk  Assessment  Guidance for
Superfund: Volume  I;  Human Health Evaluation Manual. Part B  (EPA
1991).  Risk   Assessment   Guidance  for   Superfund.   Volume  lit
Environmental  Evaluation Manual  (EPA.  1989c).  Superfund Exposure
Assessment Manual  (EPA.  1988) .  Health Effects  Assessment Summary
Tables  (EPA.  1990c). and  the National  Contingency  Plan.   This
section  presents  a summary of  the  Baseline  Human Health  Risk
Assessment for exposure of humans to contaminants existing within
the groundwater that  are attributable to the site.   The baseline
risk assessment provides the basis for taking action and indicates
i-iie exposure pathways that need to be addressed by  the remedial
action.   It serves as  the baseline indicating  what risks could
exist if no action were  taken at the site. This section of the ROD
reports the results of the baseline risk assessment conducted for
this site.

The purpose of this risk assessment was  to compile  and evaluate
information  collected  in  the  site  investigation in order  to
estimate the upper limit of potential health  risk which  may be
present  at the  site with  respect  to  ground  water.   In  the
evaluation of potential human exposure scenarios, on-site sampling
and  analytical results  were used in conjunction with  current
federal and state guidance  documents and professional judgement to
estimate the potential  human health risk attributable to ground
water contamination resulting from past site-related operations.
The  "risk"  values  generated  within  this human  health  risk
assessment will reflect the  plausible upper limit to  the actual
risk of  cancer posed by  the site  under the  exposure scenarios
evaluated.   These estimates were  compared to the EPA's target risk
range of  1 X  10'4  to 1 X  10'6  (1  in 10,000  to l in 1,000,000
respectively)   excess  cancer  risks  for hazardous  waste  site
remediations.   The NCP stipulates a 1 X 10"6 risk level as a point
of departure  in risk management.   When evaluating ground water
contamination,  EPA  also considers  the Maximum  Contaminant Levels
(MCLs)  in the Safe Drinking Water Act as  appropriate remedial

                               26

-------
s

           •8
                   I
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                                         (S
                                                   i
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                                                - «4 *i «>> «••>•«
                           27

-------
targets.  Such estimates, however,  do not necessarily represent an
actual  prediction  of the  risk.    Non-carcinogenic impacts are
quantified  by  the "Hazard  Index" which  is the  ratio  of site
concentrations  of  a contaminant  of  concern  to  a  reference
concentration  that  causes  a  non-carcinogenic  impact.    EPA's
remedial goal  is  to reduce the "Hazard  Index" at  a site to less
than 1.0.

The risk assessment was  performed  based on the assumption that a
residential well was installed at the site  boundary to be utilized
for domestic use.   This imaginary well was  assumed  to be installed
at a depth  of  60  feet, which is assumed to  be about five to ten
feet into the top  of the Carter-Wellington (bedrock) aquifer.  This
assumption  is  considered  the "worst case scenario".    Also,  in
predicting the  exposure  point concentrations it  was assumed that
the surface contamination at the site has been removed and will not
contribute to further ground water contamination.

The calculated  risks  are based on a  well  being  installed in the
most shallow useable  water-bearing  zone.    Ground water  in the
alluvial and upper Garber-Wellington  (bedrock) zones is considered
unusable due to TDS concentrations  in excess  of 10,000 ppm.  Since
there are no private wells  installed in the vicinity of the site at
the present time,  no complete pathway exists for current exposure
to contaminated ground water.   However,  ground water beneath the
upper portion  of  the Garber Wellington  (bedrock)  aquifer (at an
approximate  depth of  100  feet)  could potentially be  used  as  a
domestic supply.  The risk assessment was conducted  to estimate the
impact on public  health should the  pathway be  completed  in the
future.  The risk assessment is based on  the establishment of a
future pathway by  the installation  of an  immaginary drinking water
well at the  boundary  of  the site at  a depth of  60  feet below the
ground surface. This is the depth  at which a well may be screened
in a water supply with relatively  low TDS.  Calculating the risk
based on a' well installed  at this  point is the most conservative
method, and results in the  most protective  risk assessment values.

The values which are calculated in this assessment are considered
representative  of  the cancer  risk   posed by the ground  water
contamination at the site only in that they represent estimates of
the plausible upper bound limit of what is most probably the risk
range.   The true risk within the range of the upper limit and zero
is indeterminable.  What is estimated is the projected reasonable
maximum potential  additional lifetime cancer risk  and potential for
adverse health effects.  The reasonable maximum potential risk is
calculated in order to be  health protective ("health protective"
assumptions are also referred to as "conservative"  assumptions in
risk assessment terminology).

It should be noted that the risk  is an additional risk  -  it is
present  in  addition  to the baseline.   The national risk,  or
probability, that  an  individual  may develop  some  form  of cancer
from everyday sources, over a 70-year life span is  estimated at a


                               28

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 baseline of three in ten.  Activities such as too much exposure to
 the sun,  occupational exposures,  or dietary  or  smoking habits
 contribute to this high  risk.   This three  in  ten probability is
 considered the "natural incidence" of cancer in the United States.
 To protect human health,  the EPA has set the range from one in ten
 thousand to  one in one  million excess  cancer incidents  as the
 remedial goal for Superfund sites.  A risk  of  one in one million
 means  that  one  person out  of  one million  people might develop
 cancer as a result of  a lifetime exposure to the site.   This risk
 is above and beyond the "natural incidence"  of three in ten.

 Identification of Chemicals of Concern

 Contaminants of concern  (COCs)  are  those contaminants  which are
 most likely to contribute significant cancer risks or  non-cancer
 health effects.    Fifteen  COCs  were originally  considered  for
 performance of the risk assessment, since these chemicals provided
 an excess risk from the Source.Control Operable Unit (SCOU) -  These
 contaminants were arsenic,  barium, beryllium,  cadmium,  chromium,
 lead,   nickel,   vanadium,  vinyl  chloride,  1,2-dichloroethane,
 trichloroethane,  benzene, chlorobenzene,  bis(2-chloroethyl)ether,
 and 1,4-dichlorobenzene.

 In order to  ensure compliance  with published  EPA guidance  and
 verify that contaminants with  potential toxic  effects  were  not
 overlooked,  the  list  of COCs  was reanalyzed  using a  screening
 process.  Initially, the data set for the bedrock monitoring wells
 was  evaluated   to  identify   potential   COCs   since   current
 contamination is assumed to represent steady-state conditions,  and
 the source of  contamination  was assumed  to be  removed.   Under
 steady-state  conditions,  the contaminant mass  currently in  the
 alluvial aquifer  would  continue to contribute to contamination in
 the bedrock aquifer. The data obtained from the bedrock monitoring
 wells represented the current level of contamination  at  the depth
 of  the "assumed"  future residential well.  Data obtained from the
 alluvial aquifer were used in ground water modeling to predict the
 concentration  in the bedrock aquifer,  and  potential risk, at a
 future date.  This "assumed" future residential well is considered
 the worst-case scenario.  It is  highly improbable that anyone will
 use the  ground water at  this depth due to  the presence of high
 Total Dissolved Solids  (TDS).

As a result of the risk calculations for individual contaminants,
the list of potential COCs was further reduced by eliminating those
contaminants that presented  a cancer risk less than 1 in 10,000,000
and a Hazard Index less than 0.1.  A summary of the determination
of final COCs for this risk assessment is given in Table  6.

Toxicity Assessment

The objective  of the toxicity  assessment is to  weigh available
evidence regarding  the  potential for particular  contaminants to
cause  adverse effects in exposed individuals.  Also, the  toxicity

                                29

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                                         Table   6
                               Determination of Final COCs
                                    Double Eagle Site
Contaminants of Concern
Risk
Criterion
Calculated Risk
Exposure Pathway and Receptor
Dermal
Child/Adult
Inhalation
Child/Adult
CARCINOGENS
Aldrin2
Arsenic1
Benzene'
BeryUium'
Bisp-ChloroelhyOEthei1
Chlordane
Chloroform2
4,4-DDE i
1 ,4-^cblorobenzene1
"l ,2-DTcSoroelnane'
l.T-DTchioroelhen?
Heptachlor
Heptachlor Epoxid?
Methylene CUoridi?
Trichloroethene1
Vinyl Chloride1
1E-7
1E-7
1E-7
"ll"7
1E-7
1E-7
1E-7
1E-7
1E-7
1E~7 1
1E-7 J
1E-7
1E-7
1E-7
1E-7
1E-7
NA3
NAT
2.1E-5/4.9E-5
[ NA?
NA3
5.8E-8/1.4E-7
2.0E-7/4.7E-7
1.7E-6/4.0E-6
6.3E-8/1.5E-7
NAT
8.6E-7/2.0E-6
2.4E-6/5.7E-6
NA5
NAT
3.6E-6/8.4E-*
NA3
NA"
"NA*
1.2E^/2.9E-4
- - NA" ~
6.3E-5/1.6E-4
NA"
8.4E-6/2.1E-5
~ ~~NA' '" '
NA4
5.0E-4/1.3E-3
S.2E-5/1.3E-4
" ^NA4
NA4
4.6E-8/1.2E-7
3.0E-6/7.5E-6
1.5E-4/3.8E-4
Ingestion
Child/Adult

1.1E-4/1.8E-4
1.6E-5/3.5E-5
4.7E-5/7.8E-5
OA?
2.5E-5/4.2E-5
6.6E-7/1.1E-6
2.5E-7/4.2E-7
2.9E4)7/4.8E-7
1.4E-7/2.3E-7
2.0E-4/3.3E-4
1.0E-5/1.7E-5
1.9E-5/3.2E-5
5.6E-6/9.4E-6
8.7E-8/1.4E-7
2.2E-6/3.7E-6
3.8E-4/6.3E-4
NON-CARCINOGENS
Acetone2
Aldrin
Arsenic1
Barium"
BayUjumT
2-Butanonr
Cadmium'
CUorobenzene1
vjinQiiiimn
1,1-DTcbloToethane^
trans fi^-Dichloroethene2
Endosul&i?
Ketones2
l>rt'
Manganese^
"Methylene chloride5"
2-Memyl-4-Pentknon?
Nickel1
"Phenol2
2,43>Ln>etnyi Phenof
fhailiun?
Toluene2
Vanadium1
fXylene
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
~NA«
"IE"!
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
1E-1
NAJ
NA5
NA?
NA5
	 NA1 	
NA?
NAT" ""
2.1E-3/4.8E-3
NAT
NA?"" "
2.3E-3/5.4E-3
NAy
"' NA' 	
NAT
~ "NAT" ""
NA*
NAT
NAT
"NAT" "
NAT
N^
9.8E-l/2.3E-fO
•"". "NAT" '-
4.6E-3/9.8E-3
NA'
NA4
	 NA4" ' "
NA4
NA4
NA6
" " NA4
13E-1/6.8E-2
— w 	
1.7E-1/8.4E-2
NA4
NA4
9.5E-1/5.4E-1
' — Ny "
' 	 NA4 	
3.9E-4/2.0E-4
NAf
JNA4
NA4
NAr
NA*
4.8E+0/2.4E+0
'" " NA4 . .'
2.9E+0/1.5E-J-0
1.1E+0/3.7E-1
2.5E+0/8.2E-1
3.5E+0/1.5E+0
1.0E+1/3.3E+0
~" "0.0s"" ""
1.7E-1/5.4E-2
2.0E-1/8.8E-2
1.3E-2/4.5E-3
0/C?
6.7E-2^.3E-2
2.2E-1/6.7E-2
6.0E-1/2.0E-1
~" "NA1" "
NA»"
7.7E+2^.6E+2
1.2E+0/9.9E-2
8.0E"+l72.6E+l
OA?"
3.9E+0/1.3E+0
2.4E-2/8.1E-3
L5E+1/7.3E+6
9.7E-01/3.2E-1
OAF
5.2E02/1.7BQ2
COC from list provided by Remedial Project Manager (Allen 1993).
COC determined by initial screening process described in Section 5.2.2 of this report.
Pathway not applicable to contaminant due to low permeability coefficient. See Section 5.2.4.2 of this report.
Pathway not applicable to contaminant due to low Henry's Law Constant and/or molecular weight  See Section
5.2.4.2 of this report.
Contaminant not detected in bedrock wells.  No significant change expected.
Ketones evaluated as a group only for the inhalation pathway.
Toxicity values not available for lead.
                                        30

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 assessment  provides,   where  possible,   an   estimate  of   the
 relationship between the extent of exposure to  a  contaminant and
 the increased likelihood and/or severity  of adverse  effects.  The
 types of  toxicity   information   considered  in this  assessment
 include the reference dose (RfD)  used to evaluate  noncarcinogenic
 effects and the slope factor to evaluate  carcinogenic  potential.
 RfDs have been developed by EPA for  indicating  the potential for
 adverse health effects  from  exposure to  contaminants  of  concern
 exhibiting noncarcinogenic effects.   RfDs, which are  expressed in
 units of  mg/kg-day,  are estimates of acceptable lifetime daily
 exposure  levels   for humans,  including  sensitive  individuals.
 Estimated intakes of contaminants  of concern from environmental
 media (e.g., the amount of a contaminated drinking water) can be
 compared to the RfD.   RfDs are  derived from human  epidemiological
 studies or animal studies to which uncertainty  factors have  been
 applied (e.g., to account  for  the use of  animal data  to predict
 effects on  humans and  to protect sensitive  subpopulations)  to
 ensure that  it  is unlikely  to underestimate the potential  for
 adverse noncarcinogenic  effects to occur.   The purpose  of the RfD
 is  to provide  a benchmark against which the sum of  the other doses
 (i.e.  those projected from human exposure to various environmental
 conditions)  might be compared.  Doses that are significantly higher
 than the RfD may indicate that an inadequate margin of  safety could
 exist for exposure to that substance  and that an adverse health
 effect could occur.

 No  RfD or  slope  factors are available for the dermal route  of
 exposure.  In some cases, however, noncarcinogenic  or  carcinogenic
 risks associated  with dermal exposure  can be  evaluated using  an
 oral RfD or an oral slope  factor.  Exposures via the  dermal route
 generally  are  calculated and  expressed as absorbed doses.  These
 absorbed doses are compared to an oral toxicity value  that is also
 expressed   as  an absorbed dose.  Toxicity  information used in  the
 toxicity assessment for  the Site was obtained from the  Integrated
 Risk Information System  (IRIS).   If values were not available from
 IRIS,  the Health Effects Assessment  Summary Tables   (HEAST)  were
 consulted.

 For  chemicals that   exhibit  noncarcinogenic  health  effects,
 authorities  consider  organisms  to have repair  and detoxification
 capabilities that must be exceeded by some critical concentration
 (threshold) before the health  is adversely affected.   For example,
 an  organ can have a large number of cells  performing the same  or
 similar functions.  To lose organ function, a significant number of
 those  cells must be  depleted or  impacted.  This  threshold  view
 holds  that  exposure to some amount of a contaminant is tolerated
without an appreciable risk of adverse effects.

Health criteria for chemicals exhibiting noncarcinogenic effects
 for use in risk assessment are generally developed using  EPA's RfDs
developed by the Reference Dose/Reference Concentration ("RfD/RfC")
Work Group and included in the IRIS.
                                31

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 For  chemicals that exhibit carcinogenic effects, most authorities
 recognize that one or more molecular events can evoke changes in a
 single  cell or a  small number of  cells  that can  lead to tumor
 formation.   This  is  the non-threshold theory  of carcinogenesis
 which  purports  that  any level of  exposure to  a  carcinogen  can
 result  in some finite possibility of generating the disease.


 EPA's Carcinogenic Risk Assessment Verification Endeavor  (CRAVE)
 has  developed  slope factors  (i.e.,  dose-response values)   for
 estimating  excess  lifetime cancer  risks  associated with various
 levels  of lifetime exposure  to potential  human carcinogens.   The
 carcinogenic slope  factors  can be  used to  estimate the lifetime
 excess  cancer   risk associated with exposure  to a  potential
 carcinogen.  Risks estimated using slope factors  are considered
 unlikely to underestimate actual risks, but they may overestimate
 actual  risks.    Excess  lifetime  cancer  risks  are  generally
 expressed in scientific notation and are probabilities.  An excess
 lifetime cancer risk of 1 x 10"6 (one in one million), for example,
 represents  the  probability that  one additional individual  in  a
 population  of  one million  will  develop  cancer as a  result of
 exposure to a carcinogenic chemical over a 70-year lifetime under
 specific exposure conditions.

 Slope  factors  (SFs)  have been  developed for estimating  excess
 lifetime  cancer risks  associated  with  exposure to  potentially
 carcinogenic contaminants of concern.   SFs, which are expressed in
 units of (mg/kg-day) "1 ,  are multiplied by the estimated intake of
 a potential  carcinogen,  in mg/kg-day, to provide  an upper-bound
 estimate  of the  excess  lifetime  cancer  risk  associated  with
 exposure at that intake level.  The term "upper bound" reflects the
 conservative estimate of the risks calculated  from the SF.  Use of
 this approach  makes  underestimation of  the  actual cancer  risk
highly  unlikely.   Slope factors are derived  from the  results of
human epidemiological studies or  chronic animal bioassays to which
 animal-to-human extrapolation  and uncertainty factors  have been
 applied( e.g., to  account for the use of animal data  to predict
 effects on humans).

There are varying degrees of confidence in the weight of evidence
 for carcinogenicity of a given chemical.   The EPA system involves
 characterizing the  overall  weight  of  evidence for a  chemical's
 carcinogenicity based on the availability of animal,  human,  and
other supportive data. The weight-of-evidence  classification is an
attempt to  determine the likelihood that the agent  is a human
 carcinogen,  and thus, qualitatively affects  the estimation   of
potential health risks.   Three  major  factors are  considered in
 characterizing the  overall weight of evidence for carcinogenicity:
 (1)  the quality  of  evidence from human  studies; (2) the quality of
evidence  from  animal   studies,   which  are  combined  into  a
characterization of   the  overall weight  of  evidence   for  human
carcinogenicity; and  (3)  other  supportive  information which is
assessed to determine  whether the overall  weight of  evidence


                               32

-------
 should be modified.  EPA uses the weight of evidence classification
 system to categorize carcinogenicity of contamination as one of the
 following  five groups:

      Group A - Human Carcinogen: This category indicates that there
      is sufficient evidence from epidemiological studies to support
      a causal  association between an agent and cancer.

      Group B - Probable Human Carcinogen:  This category  generally
      indicates that  there  is at  least  limited  evidence  from
      epidemiological  studies of carcinogenicity to  humans (Group
      Bl) or that, in the absence of adequate data on humans,  there
      is sufficient  evidence of carcinogenicity in  animals (Group
      B2)

      Group C - Possible Human Carcinogen :  This category  indicates
      that  there is  limited evidence of carcinogenicity in animals
      in the absence of  data on humans.

      Group D  - Not Classified: This category indicates  that  the
      evidence  for carcinogenicity  in animals  is  inadequate.

      Group E  -  No  Evidence  of  Carcinogenicity  to Humans; This
      category   indicates   that   there   is   no   evidence   for
      carcinogenicity  in  at least  two adequate  animal  tests  in
      different  species,  or in both  epidemiological  and animal
      studies.

 Several of the initial chemicals of concern have been classified as
 potential  carcinogens  by EPA.    Each of  these  also have been
 assigned a carcinogenicity weight-of-evidence category.    These
 chemicals  are presented  in Table 7 with the respective Referenced
 Doses  and  Potency Factors.

Human Risk Characterization

 The purpose of the human risk characterization is to estimate  and
 characterize  the potential human cancer  risks  and non-cancer
 adverse health effects associated with  exposure to contaminants
released from the site into the ground water.

Exposure pathways evaluated in this risk assessment included dermal
contact,  inhalation, and ingestion of contaminants in the ground
water  to   offsite  residents.   The  pathways were  based  on  the
assumption that a residential  well will be installed at the site
boundary.

The risk assessment was based on Reasonable Maximum Exposure  (RME)
factors as required by EPA guidance (Longest II 1992).  Use of  the
RME factors provided  a calculation of the highest exposure that
could  reasonably  be expected  for the pathways  analyzed.   This
conservative calculation is intended to account for uncertainties
in contaminant concentration and variability in exposure parame-

                               33

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                                         Table 7
               Reference Doses and Slope Factors for Contaminants of Concern
                                     Double Eagle Site
Contaminant of Concern
Acetone
Aldrin
Arsenic
Barium
Benzene
|Bu(2-chloioethyl)Ether
2-Butanone
fTpHmtiim
Chlordane
Chlorobenzene
Chlorofonn
4,4-DDE
1,2-DJchloroethane
1 ,4-Dichlorobenzene
1,1-Dichloroetbane
1,1-Dicbloroethene
trans 1,2-Dichloroethene
Endosulfan

Heptachlor
Heptachlor Expoxide
Ketones3
Manganese
Methylene Chloride
2-Methyl-4-Pentanone
Phenol
Thallium
Toluene
TricUoroethene
Vinyl Chloride
Xytene
RfD(O)
ing/kg/day
l.OE-014
3.0E-O5
3.0E-04
7.0E-02
-
_i
6.0E-017
5.0E-04
6.0E-05
2.0E-02
l.OE-02
_i
_i
— '
9.0E-03
9.3E-03
2.0E-O2
5.0E-05
5.0E-04
1.3E-05
NA4
5.0E-03
6.0E-02
5.0E-27
6.0E-01
8.0E-05
2.0E-01
-'
_i
2.0E+00
RfD(I)
rng/kg/day
-l
-'
_i
_i
_i
_i
2.9E-01
_i
_i
5.0E-03
_i
_i
-'
[_ 2.0E-01
l.OE-01
_ i
-'
_i
_j
-'
2.9E-01*
l.OE-04
8.6E-01
_i
_i
__i
l.OE-01
_i
-1
9.0E-02
SF(O)
mg/kg/day
NA2
1.7E+01
1.8E+00
NA2
2.9E-02
1.1E+00
NA2
_i
1.3E+00
NA2
6.1E-03
3.4E-01
9.1E-02
2.4E-02
NA2
6.0E-01
NA2
NA2
4.5E+00
9.1E+00
NA4
NA2
7.5EO3
NA2
j
NA2
-'
1.1E-02*
1.9E+00
_i
SF(I)
mg/kg/day
NA2
1.7E+01
5.0E+01
NA2
2.9E-02
1.1E+00
NA2
6.3E+00
_i
NAZ
8.1E-02
_i
9.1E-02
-'
NA2
1.2E+007
NA2 .
NA2
4.5E+00
9.1E+00
_ i
NAZ
1.6E-03
NA2
_J
NA2
^Ji
6.0E-036
3.0E-01
_'
RfD(O) =       Oral reference dose for non-carcinogenic effects
RfD(I) =        Inhalation reference dose for son-carcinogenic effects
SF(O) —        Oral slope factor for carcinogenic effects
SF(I) =         Inhalation slope factor for carcinogenic effects

- indicates data were not available from IRIS (1993) or HEAST (1992).
NA indicates contaminant hi1* not been dB>pnf"tnted to exhibit carcinogenic effects in
Ketones include acetone, 2-butanooe, 2-hexanone and 2-methyl-4-pentmoae,
Ketones evaluated individually for oral pathway.
RfD for 2-butanone,
Toxiciry factors provided by EPA Region 6 (Rancher 1993a).
Toxicity factors provided by EPA Region 6 (Raucher I993b)
                                        34

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 ters.    An estimate  of  average exposure  is calculated  by using
 average  or  central  tendency  factors  (Central  Tendencies  are
 discussed below).

 The exposure  point  concentrations  were  based  on  groundwater
 modeling performed in the RI. Exposure concentrations were modeled
 for five year  time  intervals.   The highest  concentration occurs
 atyear 0.  Risk calculations fcr child exposure  are based on the
 assumption that the  exposure point concentration remains unchanged
 over the  six-year exposure duration.   The  highest risk  would,
 therefore,  occur using  the exposure concentrations from year 0.
 Risk calculations  for adult exposure are completed  for five year
 intervals  and added  to  account  for  a  30-year  exposure  to
 contamination in the bedrock water supply system.  The highest risk
 would,  therefore,  occur from year 0 through year 29.

 Central Tendencies

 Based on a February 26, 1992, memorandum from Deputy Administrator
 F.  Henry Habicht, EPA is  required  to  evaluate both  "reasonable
 maximum exposure"  (RME)  and  "central  tendency"   in the  risk
 assessment at Superfund sites.  The exposure assumptions associated
 with the RME have been used to  estimate  the baseline risks  and
 ultimately  the remedial action  goals  at  sites.   The  "central
 tendency"  scenario represents  the risk from more of an "average"
 exposure, compared to a  "reasonable maximum"  exposure.

 A comparison of the differences in the risk assumptions between the
 RME  and central tendency is shown in Table  8.

 Risk Summary

 Potential exposures to contaminants in the ground water at the DER
 site have been evaluated and the resultant potential for adverse
 health  effects has   been  estimated.    Exposure  scenarios were
 developed based on the assumptions that the source of  contamination
 will be removed, and a residential well will be installed  at  the
 site boundary.  The only  populations exposed would be the adult and
 child residents using the  assumed  future well.   However, it  is
 highly  unlikely that anyone would  use  the ground  water at this
 depth (60 feet) for domestic purposes.

 Thirty  contaminants  were  identified  as   COCs  based  on risks
 presented by dermal contact, inhalation  exposure,  and ingestion of
 ground water  contaminated by the DER site.

A summary of the risks calculated using RME factors is presented in
Table 9.  Cancer risks for both adult and child receptors are above
the EPA goal of 1 in  1,000,000 for all exposure pathways.   Cancer
risks for inhalation  and ingestion are above the 1 in 10,000 upper
 end  of  acceptability.   The total cancer risks from residential
ground water exposure were 36 in 10,000  (3.6E-03) and 17 in  10,000
 (1.7E-03) for adults  and children, respectively.

                               35

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                               Table 8
Exposure Assumptions for Reasonable Maximum Exposure and Central Tendency
          Dermal Contact, Ingestion and Inhalation of Groundwater
                   Off-site Resident Future Use Scenario
                           Double Eagle Site

DERMAL
Age Group (years)
Days Exposed (per year)
Years Exposed (per 70 year life)
Body Weight (kg)
Surface Area Exposed (cm2)
Hours Exposed per Day (or/day)
Event Frequency (I/day)
INGESTION
Age Group (years)
Days Exposed (per year)
Years Exposed (per 70 year life)
Body Weight,(kg)
Intake Rate (L/day)
Reasonable
Maximum
Exposure
Child

1-6
350
6
15
7200
0.2
1
Adult

18-70
350
30
70
20,000
0.2
1
Central
Tendency
Child

1-6
350
6
15
7200
0.2
1
Adult

18-70
350
9
70
20,000
0:2
1

1-6
350
6
15
1
18-70
350
30
70
2
INHALATION
Age Group (years)
Days Exposed (per year)
Years Exposed (per 70 year life)
Body Weight (kg)
Intake Rate (mVday)
Volatilization Factor (Lfar)
1-6
350
6
15
5
0.5
18-70
350
30
70
15
0.5
1-6
350
6
15
0.7

1-6
350
6
15
5
0.5
18-70
350
9
70
1.4

18-70
350
9
70
15
0.5
                            36

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              Table 9
Risk Summary for Groundwater Exposure
           Double Eagle Site
Cancer Risk
Hazard Index (HI)
Pathway
Dermal
Inhalation
Ingestion
Total Risk
Dermal
Inhalation
Ingestion
Total HI
Child
3.0E05
8.9E-04
8.1E-04
1.7E-03
9.8E-01
9.0E+00
8.9E+02
9.0E+02
Adult
7.0E-05
2.2E-03
1.4E-03
3.7E-03
2.3E+00
4.6E+00
3.0E+02
3.1E+02
          37

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The Hazard  Indices  for both adult and child receptors were above
the EPA goal of 1.0  for the ingest ion and inhalation pathways.  The
total Hazard Index  representing residential ground water exposure
is  310  (3.1E+02)   for adults and 900  (9.0E+02)  for children.
Results of the risk  calculations indicated that adults and children
are at hazard  from  exposure to contamination in the ground water
for potential  carcinogenic and toxic effects.

A summary of the risks  calculated using average exposure factors is
presented in Table 10.  Although use of these factors decreased the
risks  for  the adult  receptors  for  the  dermal  and  inhalation
pathways  and  for  adult and child receptors for the ingestion
pathway, the changes were  not  significant enough to  change the
conclusions  of this  assessment.    The  total cancer  risks  from
residential ground water exposure were reduced to 13 in 10,000 and
15 in  10,000  for adults and children, respectively.   The total
Hazard Index representing ground water exposure was reduced to 81
for adults and 630  for children.

Site-specific maximum contaminant levels were compared  against the
drinking water Maximum Contaminant Levels (MCLs) in Table 11.  As
part of the modeling effort, the estimated time for contaminants to
attain MCLs through natural  attenuation was  calculated.   These
calculations were made assuming that the  surface contamination was
removed,  and  would   not   contribute  as  a  future  source  of
contamination  in the ground water.  The MCLs were exceeded for four
metals including barium, cadmium, manganese and thallium.  Barium
is expected to reach the MCL by year 65, based on computer modeling
conducted as part of the RI.   Manganese is not expected to reach
the MCL level  in the next 150 years.  Since the concentrations of
cadmium and thallium were not expected to change significantly over
time, no estimate was made as to how long it would take to achieve
MCL  levels.    Barium,  cadmium,  manganese and thallium are  not
expected to  reach  acceptable health risk levels in the  next 150
years.

Lead was detected in the alluvial wells and was a contaminant of
concern during the SCOU.   However, lead was not modelled as part
of the GOU RI because lead was not detected during the first round
of sampling of the upper Garber-Wellington  (bedrock)  monitoring
wells.    Subsequent to the  modeling  effort  however, lead  was
detected during the second  round of  sampling.    Three  "bedrock
monitoring wells'* (BMWs) are installed around the perimeter of the
DER site.  BMW-i and BMW-6 revealed lead at 193 parts per billion
(ppb) and 83.6 ppb respectively.   BMW-2 revealed  lead at less than
5 ppb,  which is below the final cleanup level of 15 ppb considered
protective for ground water usable for drinking water.   Therefore,
modeling will be conducted to determine the threat to human health
and the environment posed by lead present in the ground water, as
part of  the Remedial  Design (RD)  for the GOU,  when the RD is
initiated.
                               38

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              Table  10
Risk Summary for Groundwater Exposure
       Average Exposure Factors
           Double Eagle Site
Cancer Risk
Hazard Index (HI)
Pathway
Dermal
Inhalation
Ingestion
Total Risk
Dermal
Inhalation
Ingestion
Total HI
Quid
3.2E-05
8.9E-04
5.8E-04
1.5E-03
9.8E-01
9.4E+00
6.2E+02
6.3E+02
Adult
2.8E-05
8.6E-04
3.7E-04
1.3E-03
8.8E-01
1.8E-01
8.0E+01
8.1E+01
         39

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                                         Table  11
                           Comparison of Contaminant Concentrations
                    With Drinking Water Maximum Contaminant Levels (MCL)
                                      Double Eagle Site
Contaminant of Concern
Maximum Modelled Concentration
mg/L
MCLs
mg/L
CARCINOGENS
Aldrin
Arsenic
Benzene
Beryllium
Bis(2-chloroethyl)Rher
Chlordane
Chlorofbnn
4,4-DDE
1 ,4-Dichlorobenzene
1 ,2-Dichloroethane
1,1-Dichloroethene
Heptacblor
Heptachlor Epoxide
MeJhylene Chloride
TricbJoroetbene
Vinyl Chloride
1.2E-03
1.7E02
3.0E-01
O.OE+00
4.2E-03
7.6E-05
7.6E-03
1.6E-04
1.1E03
4.0E-01
3.2E-03
7.8E-04
1.1E-04
2.1E-03
3.6E-02
3.6E-02
NON-CARCINOGENS
Acetone
Barium
2-Butanone
fadnnhim
Chlorobenzene
l,l-Dichk>ne%ane
trans 1,2-Dichloroethene
Endosulfai

Ketooes
Lead
Manganese
2-Memyl-4-Pentaoone
Mercury
Nickel
Phenol
Selenium
Thallium
Toluene
Xylsae
1.7E+00
1.1E+01
1.6E-KX)
1.6E-03
4.2E-03
1.1EO1
7.0E-02
4.7E-04
1.7E+00
O.OE+00
6.0E+01
6.3E+01
5.9E-05
O.OE+00
3.7E+01
O.OE+00
1.9E-02
3.0E+00
1.6E+00
NA
5.0E-02
5.0E-03
4.0E-03
NA
NA
l.OE-01
NA
7.5E-02
5.0E-03
7.0E-03
4.0E-04
2.0E-04
NA
5.0E-03
2.0E-03

NA
2.0E+00
NA
5.0E-03
NA
NA
l.OE-01
NA
NA
1.5E-02
5.0E-02
NA
2.0E-03
5.0BO1
NA
5.0E-O2
2.0E-03
l.OE+00
l.OE+01
MCL
Excursion

NA
—
/•
—
NA
NA
—
NA
—
/
—
y
—
NA
W
/

NA
/
NA
—
NA
NA
-
NA
NA
—
/
NA
—
—
NA
—
/
J
—
NA = MCL not promnlpatfrd tor this contaminant.
- = Maximum concentration did not exceed the MCL.
     Maximum concentration exceeded me MCL.
                                         40

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 The MCLs were  exceeded  by five organics including  benzene,  1,2-
 dichloroethane, heptachlor, trichloroethane, and  vinyl chloride.
 These five contaminants were  also the major contributors  to the
 cancer risks  calculated  for  the  exposure  pathways.   Based  on
 groundwater modeling, benzene is expected to  reach  the MCL level by
 year 145.  1,2-Dichloroethane is expected to  reach  the MCL level by
 year 155.   Heptachlor is expected to reach  the MCL  level  by year
 30.  Trichloroethane is expected to reach the MCL level by year 70.
 Vinyl chloride is  expected to reach the MCL  level by  year  105.
 Benzene,  heptachlor,  trichloroethane,  vinyl  chloride and  1,2-
 dichloroethane will take more than 150 years to achieve acceptable
 concentrations from a human health risk standpoint.

 Contaminants  in the groundwater present a hazard  for all exposure
 pathways.   Contaminant concentrations will  continue to decrease;
 however, some of  the contaminant concentrations will remain above
 acceptable  levels  150  years  from now  both from a  risk and  a
 regulatory  standpoint.


 Uncertainties Associated with the Human Health Risk Calculations

 Within the  Superfund process,  baseline quantitative risk  assess-
 ments are performed in order to assess  the potential human health
 impacts of a given site under currently existing conditions.  They
 are performed in  order  to provide risk managers with  a numerical
 representation of the severity of contamination  present  at the
 site,  as  well  as  to  provide an  indication  of  the potential for
 adverse  public health effects.   There  are  inherent and  imposed
 uncertainties  in  the risk  assessment methodologies.

 This section addresses potential sources of uncertainty in the  risk
 estimates; possible impacts of the various sources  of uncertainty;
 and potential bias in the risk estimates.  This discussion provides
 a context in which the significance and limitations of the various
 results can be better understood to evaluate  the overall potential
 health impacts  of the DER  site.

 Site Characterization

 This assessment addresses only  the risks due to exposures to ground
 water from a  future residential well  assumed to be placed  at the
 point  of   highest  contamination  at   the   facility   boundary.
 Analytical results from only one bedrock ground water  well sampling
 event  were  available during the  preparation of  this assessment.
 Results from  additional  sampling events are  required to consider
 the effects of seasonal variations and analytical variability.  All
 analytical  results are  understood to  exist within a  range of
 potential  error  due simply to  the  state of  the  science of
 analytical  chemistry.     However  EPA's  analytical  results  are
 consistent with acceptable standards  within the U.S.  Science of
Analytical Chemistry Community.

                                41

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Estimation of Exposure Point Concentrations

The ground water modeling utilized to estimate the exposure point
concentration is  discussed in the RI.   The COCs which  were not
modeled    were    evaluated    by   considering   a    consistent
dilution/attenuation factor for the modeled parameters.

Some of the contaminants identified as COCs originally in the SCOU
were not detected in the bedrock wells and based on modeling were
not expected  to move down significantly from  the  upper aquifer.
These contaminants were not evaluated in the risk assessment.
Evaluation of Toxicitv and Associated Constants

The estimation of potential human health impacts due to exposure to
site-related  contamination utilizes  various  toxicity  constants
derived by the EPA or approved by  EPA  for use in human health risk
assessments.  These  constants are developed based on information
derived  from direct  exposure (animal)  or  human  epidemiological
studies.  Intersex and interspecies extrapolations of toxicological
information require that one accept assumptions including metabo-
lism, detoxification  ability,  neoplastic disease  initiation,  DNA
repair mechanisms, etc.   These extrapolations  result in inherent
errors which  increase the uncertainty in estimates  of potential
effect.   Modifying  factors and uncertainty  factors  are inserted
which intentionally increase the risk  estimates in order to ensure
*-.*-& protection of human
The interpretation of the results of the animal studies upon which
the  initial toxicity  evaluation  is founded  can be  difficult.
Ambiguous or questionable results may produce a number of equally
valid,  but  conflicting  interpretations.    Guidelines  for  the
interpretation  of laboratory  (toxicological)  results demand  an
extremely conservative  interpretation of available  results.   The
uncertainty which  this  builds into the estimates of  toxicity is
acknowledged, but  this  conservative approach provides  a  level of
protection for the potentially exposed individuals.

The toxicity factors for some contaminants are  not  available or
have been withdrawn pending further study.  To allow for evaluation
of  these  contaminants,  they have been  grouped  with  similar
chemicals   and   are  evaluated   using   toxicity   factors   from
contaminants within  the group.   The contaminants grouped in this
assessment  are  ketones  which  include  2-butanone,  2-hexanone,
acetone, and 2-methyl-4-pentanone.

Exposure Assumptions

The  exposure  assumptions used   in a  risk  assessment  require
professional judgement.  Often conservative default assumptions are
used.  The issues regarding determination of appropriate exposure
assumptions are:


                               42

-------
      The frequency  and duration of exposure.

      The transfer of material from environmental media  to  target
      organs.   That  is, the  adsorption across  skin,  the absorption
      by the gut,  the absorption  by  the lungs;  and  finally  the
      transfer  from  the blood  to the target  organ.

      The quantity of material presented to  the body.   That  is  the
      ingestion rate, the inhalation rate,  the surface area exposed
      and the body weight.

 The  default assumptions used for this risk  assessment were  the
 Reasonable Maximum Exposure (RME) factors.  The risk calculations,
 therefore, represent the highest exposure that could reasonably be
 expected for the  given pathways.

 An  estimate of average  exposure is calculated using average or
 central  tendency  factors.  Use of the average  factors affected  the
 risk calculations for adult exposure  in all'three pathways  since
 the  exposure  time was reduced  to nine years.   Exposure through
 ingestion of  ground water was  also affected  since the  ingestion
 rates  for adults  and children were reduced to 1.4  L/day and  0.7
 L/day,   respectively.    To  simplify  the  calculation  for   adult
 exposure the contaminant concentration was assumed to be  unchanged
 during the nine year exposure period.

 Use  of the central tendency factors decreased  the calculated  risk,
 but  did  not significantly affect the status of  the COCs.

 Risk Characterization

 A number of  assumptions were also made in estimating the outcome of
 potential human exposures to  site-related compounds.   Carcinogens
 in combination are  presumed to  exert their effect in  an additive
 fashion,  whereas  synergism  or antagonism may be present in some
 cases.   Non-carcinogens  are also presumed  to act in  an additive
 fashion; however, this approach does not take  into consideration
 that different contaminants  target different organs  and   organ
 systems.  Particularly  sensitive populations or individuals may
 exist, which may not become obvious until after exposure.

Assumptions  regarding  exposure  are  often  very  conservative.
Uncertainties entering into the  analysis from  the  initial measure-
ment  of  dose and animal weight  in the  first lab  study to the
 interpretation of lab results to extrapolation  between species to
the modeling of environmental dispersion,  as well as other issues
have a compounding (multiplicative) effect on the final  uncertainty •
of the risk estimate.
                                43

-------
Effects seen at high doses  (such as the doses to which laboratory
animals are often exposed) are often not seen at low dose exposures
such as those typically experienced in environmental contamination.
In  order  to be conservative, it is  commonly assumed that cancer
incidence varies with dose in a  linear or semi-linear fashion even
at  extremely low dose levels, but the validity of  this assumption
is  currently an issue of considerable debate.

Ecological Risks

The Ecological Risk Assessment  (ERA) is an  integral  part of the
RI/FS  for  the  Double Eagle  site.   The  purpose of the  ERA is to
determine current and/or potential baseline impacts on ecological
receptors that are  attributable to toxicological stress from the
unremediated Double Eagle site.   Specific  objectives  within the
overall purpose include:

     Identification  of  current/potential   toxicant and  habitat
     stressors;

     Identification of representative floral and faunal receptors
     in the aquatic setting;

     Assessment of endpoints;

     Characterization of biotic receptors;

     Assessment of  relationships between toxicant stressors and
     adverse affects;

-    Assessment of  exposure using ecological  and toxicological
     stressor components; and

     Integration of all  above-noted components for  ecological risk
     estimation and description of sources  of uncertainty.


Toxicant Stressors

Concentrations of seven  (7)  organic  and eight (8)  inorganic COCs
were predicted for  surface water  in the  North  Canadian River
adjacent  to the  Double  Eagle  site  from  ground  water  inflow.
Further  model predictions   were   used  to  estimate  contaminant
concentrations   in   river-borne   suspended   sediment  and   in
interstitial water of vadose zone.  Table 12 presents the predicted
concentrations of the COCs by media and the estimated arrival time
for  those  contaminants.     For  the  purpose  of  this  ERA,  all
contaminant  concentrations  used  were  based  on  a  worst-case
scenario.   The worst-case scenario was developed by choosing the
                                44

-------
                                            Table   12
                               Predicted Concentrations of Contaminants
                               of Concern for the North Canadian River
                                     near the Double Eagle Site
Contaminant of Concern
Organics
Vinyl Chloride
1,2-Dichloroethane
Trichloroethane
Benzene
Chlorobeazene
1 ,4-Dichlorobeozene
bis(2-chloroethyl)ether
Inorganics
Arsenic
Barium
Beryllium
Cadmium
{ --ftpftffm^ n^
IffA
Nickel
Vanadium
Predicted Concentration by Media
Surface
Water1
(ug/L)
•
3.40E-02
1.40E-02
1.40E-02
9.60E-02
3.50E-02
4.00E-03
l.OOE-03

1.85E-01
1.49E+02
5.00E-03
2.00E-03
8.90E-02
2.69E+00
6.30E-02
7.81E+00
Interstitial
Water1
(ug/L)

3.40E-02
1.40E-02
1.40E-02
9.60E-02
3.50E-02
4.00E-03
l.OOE-03

I.85E-OI
1.49E+02
5.00E-03
2.00E-03
8.90E-02
2.69E+00
6.30E-02
7.81E+00
Suspended
Solids'
(ug/Kg)

0
0
0
0
0
0
0

7.56E+01
0
1.4SE02
8.00E-04
6.67E-01
7.08E+01
6.92E-02
1.09E+01
Estimated
Arrival Time1
(Years)

115
115
115
115
115
115
115

1250
115
2000
1150
115
15000
2800
900
J-   Frani Chapter 4.0 of
2. Assumed equal to surface water
3. Determined by the equation:
|tion Report  dated  July 1993.
   Cone. Suspended Solids = Cone. Surface Water x distribution coefficient (Kd)
                                        45

-------
most conservative assumptions as follows:  1)  The average saturated
thickness of the alluvial aquifer was assumed to be 20 feet.  2) The
low flow rate for seven  (7) consecutive days for a 10-year  period
reported by  the USGS was used to show the maximum impact  on the
river.  3)  The background concentrations  in the river for organics
was assumed  to  be zero,  and for the metals was assumed to  be the
same as for the alluvial aquifer.

Conceptual Ecological Model

For the  purpose of  this  ERA,  a conceptual  ecological  model was
developed which depicts those species  of flora and fauna, typical
of the central  Oklahoma  area,   that  may  experience stress from
habitat alteration  or toxicant  exposure.   The  model describes a
contiguous ecosystem which includes riverine benthic and surface
water communities of the North Canadian River.  Toxicant movements
in the aquatic system may be described by  the following pathways:

•    Uptake by vegetation from the vadose  (interstitial) zone and
     directly from the water column;

•    Uptake by water column invertebrates;

•    Uptake  by lower  food chain  (omnivorous)  vertebrates from
     vegetation, invertebrates and incidental suspended sediment;
     and,

•    liptake by upper food chain (piscivorus) vertebrates from lower
     food chain vertebrates and invertebrates.

Generally,  toxicants are translocated  throughout the ecosystem by
the specified pathways  where they become  available  to  flora and
fauna through  bioconcentration  and bioaccumulation.   In aquatic
systems,  the effects of toxicants can be noticeable because  of the
uptake and  bioaccumulation in the  food  web.  In  the conceptual
model, phytolankton  (green algae) and rooted vascular macrophytes
(milfoil) concentrate  toxicants from  surface water  and sediment
interstitial  water,  respectively.    Through  bioconcentration,
toxicant levels will increase at the base of the food chain.  For
many toxicants,  subsequent depuration or biological transformation
may occur; hence, there is no further translocation through the
food web.  For  the  purposes of  this ERA,  all toxicant  uptake is
considered cumulative with no  direct losses  due to mitigative
factors.

The conceptual model also includes direct uptake (bioconcentration)
by cladocerans  (water  flea)  from the  water  column.    Aquatic
vegetation (in the form of detritus), invertebrates and incidental
suspended sediment are then consumed by  omnivorous fish (Fathead
Minnow) which in turn are consumed by piscivorous fish (Largemouth
Bass).  Contaminant  uptake routes  for each  ecological  class are
summarized in Table 13.
                               46

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           Table    13
General Contaminant Uptake Routes
    Conceptual Ecological Model
    Ecological Risk Assessment
Ecological Class
Vegetation
Phytoplankton
(Green Algae)
Macrophytes
(Water Milfoil)
Invertebrates
dsdoceran
(Water Flea)
Vertebrates
ierbivorc
Fathead Minnow)
•"iscivor?
Largemoutb Bass)
Bioconcentration
Surface
Water

/


/

/
/
Interstitial
Water


/





Bioaccumulation
Suspended
Solids






/

Vegetation




/

y

Invertebrate






/
/
Fish







/
     47

-------
 Risk Characterization

 The  potential for acute and chronic toxicity due to contaminants in
 the  water column were evaluated against algae, daphnids,  fathead
 minnows and largemouth bass.  The potential for acute  and  chronic
 toxicity due to the sediment pore water COC were evaluated  against
 water milfoil.  Hazard quotients were calculated for fathead minnow
 and  largemouth  bass  considering  their trophic  levels  in this
 conceptualized   chain  of  the  food   web which  accounts   for
 bioconcentration  and bioaccumulation.   The predicted  results  for
 total potential toxic effects and hazard to the aquatic  vertebrates
 as based on  contaminant data and published  or  derived toxicity  and
 concentration/accumulation factors for the conceptualized model  are
 summarized  in Tables 14 and 15.   Essentially, neither the metals
 nor  the organics  suite  of contaminants posed  a   significant
 potential for toxicity or hazard via trophic transfer in  this food
 chain.   At the base  of  the  food  chain,  heavy metals  [beryllium,
 lead,  nickel and vanadium]  appeared to:   (1)  present potential
 chronic  toxic  effects  to aquatic  vegetation  and  (2)  present
 potential  acute  and chronic  effects  to  the  daphnids.    No
 significant  ecological risk, as defined by the hazard  quotient of
 greater than or equal to one (1), was predicted for the minnow or
 largemouth bass for any  of the toxicant stressors.  Likewise, the
 cumulative hazard quotient for both fish was less than one (1).
The methods used in this predictive ecological assessment indicated
that  ecological  receptors  at  the  base  of  the  food  web  may
experience potential risk from exposure to the toxicant stressors.
Organics  did not  present a significant  risk to  any ecological
compartment while heavy metal concentrations may potentially elicit
acute and chronic toxicity.  The  aquatic  ecosystem demonstrated
predicted impacts due to direct contact with contaminants and not
because  of  the  influence  of  bioconcentration/bioaccumulation
dynamics at the lower trophic levels.  A summary of potential acute
and  chronic toxicity  for  each ecological  compartment for  the
contaminants of concern is provided in Table 16.


Sources of Uncertainty
The model constructed for this  evaluation of ecological risk and
the semiquantitative, predictive methodologies used resulted in a
very conservative (i.e.,  over-predictive)  approach.  This approach
was  selected because  of the  a  priori decision  to weight  the
evaluation process qualitatively.   Uncertainties and assumptions
present in this evaluation included:
                               48

-------
IX)
II]
           *o
          8
                                     S
                                     Ui
                                    8
                                          o\
                                               ia
                                                    8
                                                        B)
                                                                         i

-------
                           «n
                                                                       3
                                                                       o

                                                                             g

                                                                             i
                                                                             O


                                                                             u
                                                                             en
                                                              III
u
w

oo

l-^
I
                                                                             S

                                                                             III
        e*»

          ^.
          v>
       >  -
                              50

-------
              Table 16
 Summary of Potential Acute and Chronic
Toricity for Each Ecological Compartment
    For the Contaminants of Concern
       Ecological Risk Assessment
           Double Eagle Site
Ecological Compartment
Freshwater Aquatic life .
Most Sensitive Species
Aquatic Vegetation . . :. . •
Green Algae
Water Milfoil
Aquatic Invertebrate . •
Water Flea
Aquatic Vertebrate .
Fathead Minnow (direct)
Fathead Minnow (via food chain)
Fathead Minnow (mmiilartve hazard)
T "vemouth Bass (direct)

Largemouth Bass (via food chain)
Largemouth Bass (cumulative hazard)
Potential Toricity
Acute
' : -. :.: •
-
• ' : .,--:-:":.'.'.--' :•"•:
-
-

Vanadium

-
-
-
-
-
-
Chronic

—

Vanadium
Vanadium

Vanadium

—
—
—
—
—
—
               51

-------
     No  corrections were  made  for biological modification of the
     contaminants  via detoxification,  depuration  or  other such
     biological    processes    that    can    mitigate    against
     concentration/accumulation and magnification;

     No  corrections were made for physicochemical factors such as
     partitioning/mobilization  dynamics,   pH,   percent  organic
     carbon,  etc.  that control presentation of  toxicant dose to
     organisms;

     All toxicant stressors (i.e., COCs by media) were assumed to
     be  100  percent  bioavailable  and  fully   retained in  the
     organisms;

     All  toxicant  stressors  were  assumed  to  be  transferred
     completely  from  the  abiotic  compartments  (water,  sediment,
     soil) through the food chain;

     Heavy  metal  (cadmium,  chromium,  lead,  nickel)  toxicity
     calculations were based on a water hardness of 50 mg/£ CaCO3
     and total metals analyses;

     Contributory  risk  from   background  concentrations of  the
     toxicant stressors  was not  removed from  the overall  risk
     summary;

     Ti.ne  frame  constraints   for  the  predicted   arrival   of
     contaminants  were not  considered and maximum  contaminant
     concentrations were used as a worst-case scenario; and,

     For  freshwater  species,  little  data was available  for  the
     toxic effects and bioconcentration of  vanadium; therefore, the
     criteria used were  based on  lowest value known  toxic  to
     aquatic life.


VII. REMEDIAL ACTION GOALS

Based on the review of the ground water sampling data from both the
alluvial wells and the bedrock  monitoring  wells at the DER and the
FSR sites, EPA has determined  the alluvial  aquifer and the upper
portion  of the Garber-Wellington  (bedrock)  aquifer to be a Class
III  aquifer  in   the  immediate  vicinity of the  sites.    This
classification is due to the high  TDS concentrations from past oil
and gas  production activities in  the area.    Contaminants  of
concern  detected in  the  upper portion of  the  Garber-Wellington
(bedrock) aquifer were discussed previously in Section VI, and were
provided in Table 6.   Concentrations of these contaminants exceed
the Maximum Concentration Limits  (MCLs)  and pose a 36  in 10,000
excess cancer risk to  adults that may use these zones as a drinking
water supply.
                               52

-------
 To  be classified as a  Class  III  aquifer (Guidelines for  Ground-
 Water  Classification   under  the  EPA  Ground-Water  Protection
 Strategy, EPA, 1986) , an'aquifer must have a total dissolved solids
 concentration greater than 10,000  parts per million (ppm)  and/or an
 aquifer yield of  less  than  150  gallons per day.   Although  the
 subject aquifers  yield  adequate  flow  rates  to  be  considered
 useable, the TDS of the alluvial  and upper portion  of the  Garber-
 Wellington aquifers are much  higher than 10,000  ppm.  The  average
 and maximum concentrations of  TDS in the  alluvial aquifer were
 2,460 ppm and 13,100 ppm,  respectively; and in the upper portion of
 the Garber-Wellington (bedrock)  aquifer the TDS were 34,680  ppm  and
 110,000 ppm, respectively, for the wells installed at the  DER site.

 Two remedial action objectives  have been developed  for this site:

      1)   Ensure that future  potential users of  the lower  Garber-
          Wellington aquifer  are  not exposed to  contaminants from
          the site (The lower  Garber-Wellington aquifer has  the
          potential to  be used  for  domestic purposes);

      2)   Ensure that the North Canadian River is not impacted by
          contaminants  from the site.

 Based on the results  of  the risk  assessment and  review  of  the
 ARARs,  the  affected media  is  the  upper portion of the Garber-
 Wellington  (bedrock) Aquifer.   Transport of contaminants through
 the alluvial aquifer to the river was investigated as a migration
 pathway, however,  the  resultant. contaminant levels in  the river
 were  below  levels  that warrant establishment of remedial  action
 goals (i.e., below risk-based  levels and potential  ARARs).    See
 Table 4.   Therefore,  the goals  applicable to  the contaminated
 ground  water are  the Chemical-Specific ARARs identified for  the
 upper Garber-Wellington (bedrock)  aquifer  and   the  health based
 levels for COCs necessary for protection from consumption  of ground
 water.

 Table 17 provides  a list  of the  goals  (mcls) that  the  potential
 remedial action technologies  must achieve  if  the ground  water  is
 used  as a public  drinking water source.    These  standards   are
 applicable  to  the  upper Garber-Wellington  aquifer at  a down-
 gradient well located at  the site boundary and  at  a depth of  60
 feet.

Although contaminants in the alluvial aquifer and  the upper portion
 of  the  Garber-Wellington  aquifer  are  above MCLs  for  several
chemicals, restoration  is  not  warranted since the subject portions
of the ground water is  categorized as a Class III aquifer.   Based
on the classification of these aquifers, no  further action would be
required.  However, there is  no confining  "aquitard" between the
upper and lower water bearing zones and there is still concern that
downward migration of contaminants to a deeper useable  zone could
occur.
                               53

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       Table 17
Remedial Action Goals
Analyte
Arsenic
Barium
Beryllium
Cadmium
Chromium
Lead
Manganese
Nickel
Thallium
Vanadium
Aldrin
Benzene
Bis(2- chtoroethvl) ether
Chiorobenzene
Ci orodane
C i oroform
D 3-4.4 -
Dknlorobenzene1r4-

L/IU UUIUVIT
>C1
DicW
oroet
broet
KUIO Iff.
ienel.1 -
Heneds- \2
>Sc iHoroethene tens - 1,2
Endosutfan


leplac uw
f
Heptachlor Epoxide
?eoi
- A
- H
- B
- 4
les
ceton
exaru
utono
-Me
Methytene
e
sne2-
ne 2 - (Methyl Ethyl Ketone)
ithyl - 2 - Pentanone
Chloride
Phenol
Toluene
Trichbroethene

Vinyl

Chloride
Xvlene
Goal
(mq/I)
4.7E- 6
2E+0
1.1E-1
N/A
N/A
N/A
N/A
7.8E-3
N/A
2E-3
1.3E-4
N/A
5.0E-7
5E-3
7.8E-5
2.1 E-6
3.1 E- 3
1.8 E-6
2.8E-5
3.0E-6
3.5 r-4
5E-3
2.5E-5
1.9E-8
7E-2
3.15E-2
7.85-5
1.9E-6
9.4E-7
1.8E-1
3.1 E- 2
9.4E-1
7.8E-2
1.1 E-3
9.4 E-1
6.3E-2
5E-3
3.4E-4
4.SE-6
5.6E-2
      54

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 Because  the alluvial and  upper portion of the  Garber-Wellington
 aquifers  are  Class  III  aquifers,  these  goals  are not applicable.

 VIII. DESCRIPTION OF ALTERNATIVES

 A Feasibility Study was conducted to develop and evaluate remedial
 alternatives  for the DER site for the GOU. Remedial alternatives
 were assembled from applicable remedial technology process options
 and were  initially evaluated for effectiveness,  implementability
 and cost based on engineering judgement.  The alternatives selected
 for detailed analysis  were evaluated  and compared to the  nine
 criteria  required by the NCP. As  a part of the evaluation, the NCP
 requires  that a no-action alternative be considered at every site.
 The no-action alternative  serves  as  a point of  comparison for the
 other  alternatives.

 Remedial Action Alternatives

 Four remedial alternatives were  initially considered for  ground
 water  remedial action in the Feasibility Study for the Double Eagle
 site.  These alternatives are: 1)  No Action,  2)  Limited Action,  3)
 Precipitation of Metals  and Activated Carbon  Treatment of Organic
 Contaminants,  and  4)  Precipitation  of  Metals  and  Biological
 Treatment of  Organics.   During the  initial  development of  these
 alternatives, Alternative  4 was considered inappropriate and was
 eliminated.   The cost of  Alternative  4 was significantly  higher
 than Alternative 3, yet  it did not provide an additional  level  of
 risk reduction.  The  following alternatives to address the  ground
 water  contamination at the DER site were evaluated:

 1.   No Action

 The "No Action"  alternative is  required for consideration by the
 National  Contingency Plan  and  represents  a  continuation of the
 current situation.   This  alternative establishes a baseline for
 comparison with the other alternatives.   This  alternative  does not
 provide a means of monitoring of the ground water to determine  if
 contaminant  releases  are  continuing.    Under  the  "No  Action"
 alternative,  no  activities to address  the  risks posed  by the
 contaminated  ground  water  at  the  site  would  be implemented.
 Inclusion of this alternative is required by the  Superfund law and
 is  the basis  for evaluating other alternatives.

 There are no costs associated with Alternative 1.

 2.   Limited Action

Major Components  of the Limited Action Alternative;   Components  of
this  alternative  include:  institutional  controls  to  control'
exposure to contaminated ground water, and continued ground water
monitoring  to assess changes  in  the  potential  for exposure.
 Installation  of warning  signs is included in  the alternative  to
require notification prior to drilling in the  area.   A  deed notice

                                55

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would  be  filed to  notify  future land  owners  of the  hazards
associated with the  contaminated ground water in the area of the
site.  A deed restriction was considered,  but was not pursued since
the  State of  Oklahoma does not have the  authority to  place a
restriction  in  the deed.

This alternative includes the installation  of additional ground
water monitoring wells and establishment  of a routine monitoring
and maintenance program for ground water sampling and modeling to
evaluate contaminant level reductions following removal of the
contaminant  source.  The  new wells will be installed in a deeper
zone of the Garber-Wellington than the wells presently installed at
the site, at an approximate depth of at least 100 feet below ground
surface.  The deepest wells present at the DER site are at about 60
feet deep.  The installation of additional deeper monitoring wells
further  down-gradient will  allow  the  EPA  to   ensure  that
contaminants  do not migrate deeper,  or  to any receptor  point
offsite,  and determine  if  an   offsite  source  of  contamination
exists.  Also,  these deeper wells will allow the EPA to determine
if  the ground  water  beneath  60 feet  is useable,  or has  been
previously contaminated by past oil and gas production activities
(contains high  TDS).

Modeling  conducted during  the   RI  indicates  that  MCLs will  be
achieved through attenuation in 60 to 150 years.  An  aspect of this
alternative  is  to allow  natural  attenuation  to  reduce  these
contaminant  levels  over time.  Natural attenuation  relies  on the
ground  water's  natural  ability  to  lower   the  contaminant
concentrations over time through physical,  chemical,  and biological
processes.  Routine inspections would  also be included in a formal
monitoring and  maintenance plan  to  ensure  that public  use of the
upper zone (less than  60  feet in depth) of the Garber-Wellington
aquifer does not occur prior to attainment of the remedial action
objectives.

The "Limited Action" alternative would also include monitoring of
the existing monitoring wells.  The ground water monitoring will be
conducted to determine  if  current conditions  improve through time,
remain  constant, or worsen.   The  ground water monitoring  well
sampling will be conducted on a  quarterly  schedule  for the first
two  years and   then  semi-annually until the first  "five-year
review".  After the  five-year  review, the EPA will evaluate all
data and determine  if the  sampling should be conducted annually or
less frequently.  The  site would also be  re-evaluated  every five
years ("five-year review"), to determine if further actions need to
be taken with regard to the ground water.   The five-year review
will analyze  the data  obtained and include  computer modeling  to
determine if  contaminant  level  reductions are  being achieved  as
expected, once the surface source of contamination is stabilized.

If  the  ground water  monitoring   indicates   that  detectable
concentrations  of site contaminants are found below the affected
upper  portion  of  the  Garber-Wellington  aquifer,  or  if  the


                               56

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 contaminated  portions  of the ground water show an  increase  of  30
 percent for any contaminant in any of the alluvial or upper Garber-
 Wellington  monitoring wells;  the need  for contingency  measures
 (including  active  treatment)  will  be  evaluated.    Contingency
 measures can  include one or  all of the following  elements:

          Installation of additional monitoring wells to determine
          if  the  contamination is increasing in  concentration  or
          migrating.

      •    Increasing  the frequency of sampling  to assure that a
          complete exposure  pathway does not develop.

      •    Construction of a  containment  measure such as  a slurry
          wall.

      •    Implementation of a remedial action plan for extraction,
          treatment, and disposal of contaminated ground  water.

 Although this alternative does not meet the Superfund  preference
 for  treatment  of contaminants,  EPA's  evaluation  of the  site
 specific data indicates  that  active treatment of  the  ground  water
 contamination is not warranted at this time.  Active  treatment  is
 not warranted because   l)  the contaminated ground water  aquifers
 are  Class  III  aquifers,  and 2)  the  ground water  modeling data
 showed that by the time the  ground water  contaminants reach the
 North Canadian River,  the concentrations  would be  sufficiently low
 and will not  adversely impact the river.

 General components: The  estimated time to implement this remedy  is
 12  months.     The  estimated  cost  associated  with  implementing
 Alternative 2 are: Capital  Costs:  $158,000; Annual Operation and
 Maintenance Costs: $74,880;  Total Present  Net Worth:  $1,463,056.
    \

 3.   Inorganic  Precipitation and Activated Carbon  Treatment for
     Organic  Contaminants

 Major Components of the Remedial Alternative.  The major  features
 of  alternative 3  consists  of the  following  key elements:   1)
 installation of a  ground water recovery system, 2) construction of
 an  on site   ground  water  treatment  and   discharge   system,  3)
 discharge of the treated ground water either to the North  Canadian
 River, to a Publically  Owned Treatment Works (POTW) ,  or reinjection
 to the alluvial aquifer, and 4)  implementation  of an  operation,
monitoring,  and maintenance program.

 Components of the Recovery System:   The components of  the ground
water recovery system  include installation of  additional ground
water recovery  wells  in  the area of the ground  water plume with
sufficient overlap of the  radii of  influence  to  recover the
contaminant plume.  A system of pipes from the recovery wells would
be used to convey the recovered ground water from each  well to an


                                57

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 equalization  tank for subsequent treatment.

 Implementation  of the proposed ground water recovery system will
 contain  the contaminant plume  and  reduce the contaminant  levels
 more  quickly than  natural  attenuation.   Using  the ground water
 recovery system described above, a period of approximately 25 years
 would be required  for contaminant levels to  reach the  remedial
 action  goals.      Additionally,  the  contaminant  plume  will
 theoretically be  contained thereby  mitigating  further offsite
 migration of  the  plume.

 Components of the Treatment System:  The chemical treatment  system
 that would be employed under this alternative consists of chemical
 and polymer addition  followed by filtration  to remove flocculated
 inorganic constituents.   Chemical treatment is performed using a
 reagent, such as  lime,  to increase the pH and thereby reduce the
 solubility  of  the  inorganic  constituents.    The decrease  in
 solubility  will cause  the  inorganic constituents  to  form metal
 hydroxides.  The effectiveness of the removal of flocculated  solids
 can be enhanced through  the  use of a polymer, based flocculent.
 Filtration can  then be used to  remove the flocculated solids from
 the treated water.

 After  the filtration  unit,  the  water would be treated through an
 activated carbon  unit to remove  organic  COCs  followed by direct
 discharge to the  River or discharge  to a  POTW.   Treatment of
 wastewaters using activated carbon adsorption typically occurs in
 packed-bed columns piped in series.  The activated  carbon adsorbs
 the organic based hazardous constituents by  surface attraction in
 which organic molecules are attracted to the  internal pores  of the
 carbon granules.   Very high organic removal efficiencies can be
 achieved using this process.

 Components  of the Discharge System:   The decision to discharge
 directly to the river or to a POTW is considered  a  design aspect.
 The decision would be  based on consideration of waste treatability,
 local  standards,  and  a detailed cost analysis.   This alternative
 would  have  to  meet all applicable  (Clean  Water Act)  statutory
 requirements  contained  in  a  National   Pollutant   Discharge
 Elimination  System (NPDES) permit,  and  would require  an  NPDES
 permit for an off-site discharge directly to the river.

 Components of the operation and Maintenance Program:   Since the
 ground   water  recovery  and   treatment   system  will   require
 approximately  1  year  to  install  and  25  years  to  complete
 remediation, it will be necessary to establish site access controls
 and an operation, monitoring, and maintenance program similar to
 the  program  described  under  the  Limited Action  Alternative
 (Alternative 2).

 In  addition  to  the  elements  included  in the Limited  Action
monitoring  and  maintenance  program  (site  warning signs,  deed
 notice,  sampling  and  analysis  program,  etc.),   operation  and


                                58

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 maintenance of the recovery and treatment system will be required
 under this alternative.  Operation and maintenance of the recovery
 and treatment system includes  equipment  replacement,  maintaining
 treatment reagent supplies,  operation of the treatment system, and
 disposal of residues (inorganic precipitate residues, spent carbon,
 etc.)  from the  treatment  of  contaminated  ground water.    The
 treatment residues may be  characterized as a RCRA waste due to the
 characteristic of toxicity.  Disposal of the residues would be done
 based on  the results  of  a  leachability test  conducted on  the
 residue.   Residues  that fail the Toxicity Characteristics Leaching
 Procedure (TCLP) test would require further treatment to remove the
 characteristic prior  to  disposal.    If  this  alternative  were
 implemented,  the transportation of  the  treatment residues  would
 have to meet all applicable requirements of the U.S.  Department of
 Transportation;   and  the  disposal   of  these  residues  would  be
 performed in  accordance with all requirements  contained in 40 CFR
 Part 268  - Land Disposal Restrictions.

 General Components:  The estimated time to implement this remedy is
 12  months, and approximately 25 to 40 years to complete  (to meet
 the Remedial  Action Goals).   The estimated costs associated with
 implementing  Alternative  3  are:  Total Capital Costs:  $775,000;
 Annual Operation and Maintenance Cost: $354,200; and  Total Present
 Net Worth:  $5,996,331.

 K. SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES

 The EPA uses nine criteria to evaluate alternatives for addressing
 a Superfund site.  These  nine criteria are categorized  into  three
 groups: threshold, primary balancing, and modifying.   The threshold
 criteria must be met in order for an alternative to be eligible for
 selection.  The primary balancing criteria are used to weigh  major
 tradeoffs  among alternatives.  The  modifying  criteria are  taken
 into account  after state  and public comment  is  received on the
 Proposed Plan of Action.

Nine Criteria

 The nine criteria used in evaluating all of the alternatives are as
 follows:

     a) Threshold Criteria

Overall Protection  of Hwiaa  Health and  the Environment addresses
the way in which an alternative would reduce, eliminate,  or control
the  risks  posed by  the site  to human health and the environment.
The methods used  to achieve  an adequate  level of protection vary
but  may  include  treatment   and  engineering  controls.    Total
elimination of  risk is  often impossible to achieve.   However, a
remedy must minimize  risks to  assure that human health and the
environment are protected.
                                59

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Compliance with ARARs.  or  "applicable  or  relevant  and  appropriate
requirements", assures  that an alternative will meet  all  related
federal, state, and local  requirements.

     b) Primary Balancing Criteria

Long-term Effectiveness and Permanence addresses the ability of an
alternative  to reliably provide long-term  protection for  human
health  and the environment after the remediation goals have been
accompl ished.


Treatment assesses how effectively an alternative will  address the
contamination at a site.  Factors considered include the nature of
the treatment process; the amount of hazardous materials that will
be destroyed by the treatment process;  how effectively  the  process
reduces the  toxicity, mobility,  or volume of waste; and the type
and quantity of contamination that will remain after treatment.

Short-term Effectiveness  addresses the time  it  takes  for remedy
implementation.  A potential remedy is evaluated  for the length of
time required for implementation and the potential  impact on human
health  and the environment during implementation.


Implementability addresses the ease with  which an alternative can
be accomplished.   Factors such  as  availability  or materials  and
services are considered.

Cost (including capital  costs and projected long-term operation and
maintenance costs)  is considered and compared  to the benefit that
will result from implementing the alternative.

     c)  Modifying Criteria

State Acceptance allows the state to review the proposed plan and
offer comments to the EPA.  A state may agree with,  oppose,  or have
no comment on the proposed remedy.

Community  Acceptance allows  for  a  public  comment  period  for
interested persons  or organizations  to  comment on the proposed
remedy. EPA  considers these comments  in  making  its final remedy
selection.   The  comments  are   addressed in  the  responsiveness
summary which is a part of this  ROD.

Comparative Analysis

This comparative analysis presents an analysis of each  alternative
in relation to each  other using the nine criteria.  The  analysis is
used to identify the relative  advantages of one alternative versus
another alternative.
                                60

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 Overall  Protection of Human Health  and  the Environment

 Alternative 1  does not achieve the  remedial action  objectives  and
 does not provide protection to human health and the  environment.
 Although contaminant  concentrations should decrease over time upon
 removal  of  the source material, Alternative 1  does  not provide  for
 monitoring  of  the  contaminant plume.

 Alternative 2  provides adequate protection of  human health and  the
 environment.   Because the  alluvial  and  upper bedrock  aquifers  are
 Class III aquifers, they will not likely be used as water supplies.
 Ground  water  monitoring  will  alert  EPA to  any  potential  for
 movement of  site  contaminants  to a  potential  drinking water
 aquifer.    This  alternative  will also  provide information about
 changes  in  contaminant concentrations upon removal  of the  surface
 source  of  contamination.   Upon  removal  of  the  surface source
 material, contaminant concentrations would be  expected to decrease
 due  to  natural  attenuation.   If contaminants  migrate below  the
 bedrock  portion  of the  aquifer or  towards the river,  or if  the
 contaminant levels   are  not  reduced  as expected;   contingency
 measures will be taken to ensure protection of  human health and  the
 environment.  Federal drinking water standards would be attained in
 approximately  60 -  150 years.

 Alternative 3 would provide the greatest protection  of  human health
 and  the  environment from exposure to contaminants  from the site;
 however,  active  remediation is not  warranted  at this time, since
 removal  of  site contaminants would not restore the  alluvial  or
 upper bedrock aquifers to be usable aquifers due to the presence of
 high TDS.

 comliance  with
The  individual discussions of  compliance with ARARs  within the
Feasibility Study indicated that each alternative will meet their
appropriate location-specific and action-specific ARARs.  Action-
specific  ARARs  are  listed  in Table   18.    Implementation  of
Alternative 3  is expected to  achieve the remedial  action goals
listed in Table 17 in approximately 25 years.  Alternatives 2 and
3 provide the information necessary to determine achievement of the
ground water ARARs.   Alternative 1 would not provide sufficient
information to assess  lateral  or vertical contaminant migration.
Thus, EPA would not  be able  to evaluate potentially unacceptable
risks  from exposure  to site  contaminants  either  in  the North
Canadian River or future use of the lower Garber-Wellington aquifer
as a water supply.

Long—term Effectiveness and Permanence

Alternative  3  provides  the   greatest  degree  of   long-term
effectiveness  and permanence  because the  contaminant  levels are
reduced more quickly than Alternatives  1 or  2.   Treatment of the
contaminants present in the recovered ground  water also provides a


                                61

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      n
      oc
G)

S
75


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               DC
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                                            62

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 greater degree of long-term effectiveness and permanence because
 the contaminants are  either degraded,  absorbed,  or altered to  a
 more  stable  form.     Treatment  residues   associated  with  the
 Alternative 3  are manageable and will be disposed in a manner that
 minimizes the  long-term potential  for cross  media impacts.

 However,  the success of Alternative 3 at removing the contamination
 from the alluvial and the upper portion of  the  Garber-Wellington
 aquifers is highly questionable since A) there is a possibility of
 an off site source of contamination, B) the  subject water bearing
 zones are Class III aquifers, and C) the success  of remediation of
 sites with DNAPL  contamination is suspect.  Consequently,  although
 Alternative 3  may reduce contaminant  levels  in the short term, it
 may not be significantly more effective in the long term for  the
 protection of  human health and the environment.   Contaminants from
 other  sources and  dissolved solids  from  past  oil production
 activities  would continue to  impose  a risk  to  human  health.
 Therefore,  Alternative 3 may not achieve a significant reduction in
 overall risk.

 Alternative   2   can    effectively  monitor   the    contaminant
 concentrations in  the  alluvial,   and  upper  and  lower  Garber-
 Wellington aquifers.   The reduction  in concentrations  of site
 contaminants,  upon  removal  of  the  surface  contamination,  is
 expected  to be permanent. With the source stabilized, minimal site
 contaminants will leach into  the ground water.   The reduction in
 leachate  contaminating  the ground water  beneath  the  site  is
 considered permanent.  Therefore, the reduction in. risk from site
 contaminants will also be permanent.
Alternatives  1 and  2 do  not provide  a reduction  in toxicity,
mobility, or volume through treatment.  Alternative 3  satisfies the
preference for treatment as a principal element in the alternative,
uses  treatment to reduce  contaminant levels  in recovered ground
water, and reduces the potential for transfer of the contaminants
from  the alluvial and upper bedrock aquifers to the  lower Garber-
Wellington.    However,  the   overall  reduction attributable  to
Alternative 3  is questionable, because of the presence of another
source not related to the DER site.  The  precipitation of inorganic
contaminants,  and the carbon  absorption under Alternative  3  is
considered  an  irreversible  process,  and  provides  a  permanent
reduction in toxicity and mobility.  However, the overall reduction
in toxicity may not be significant due to other potential sources
of organic contamination in the area.


Short-term Effectiveness

The short-term risk associated with Alternative 1 is a continuation
of the risk currently associated with the site.   In the short-term,


                               63

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 the risk from contaminated ground water is minimal since use of the
 ground water as a drinking water source is considered a future use
 exposure  scenario.    Over  the  short  term,   implementation of
 Alternatives 2 and 3 would not significantly increase the  risk to
 the community or site workers.  The additional risk associated with
 construction  of  a  monitoring  system  or  a  recovery   system
 (Alternative 3) can  be managed by application of engineering and
 short-term access controls.

 Transportation of treatment residues associated with Alternative 3
 can  potentially cause exposure to the  general public  and the
 environment should a mishap occur during transportation.  However,
 transportation of wastewater treatment residues  is a common and
 well managed practice in the industry and is not expected to cause
 a significant increase in the short-term risk.   The  transportation
 of these residues would have to be conducted in compliance with all
 applicable requirements of the U.S. Department  of Transportation.


 Implementability

 Alternative 1 is the easiest to implement.   Alternative 2 involves
 installation of a  ground water monitoring  system which does not
 require significant construction activity.   Alternative 3 requires
 the same elements of Alternative 2  with the  addition of a recovery
 and treatment system.  If the treated  ground water were discharged
 directly to the river, an NPDES permit would  be required.   This
 could delay implementation.   The construction  of  a ground water
 monitoring and/or recovery and treatment  system with operation,
 monitoring, maintenance, and residual  material disposal activities
 are standard practices in the industry and are readily available.
 Adequately trained  and  experienced  personnel  are  also  readily
 available for the implementation of the system.

 No free phase  contamination was encountered  during the drilling
 operations at the DER site, but some of the chemicals  detected in
 the ground  water beneath the DER  site such  as dichloroethane,
 trichloroethane and dichlorobenzene  are  associated  with DNAPL
 contamination.  Past experience with ground  water recovery systems
 indicates a high degree of difficulty  in restoring ground water at
 sites that contain chemicals associated with DNAPL contamination.
 Therefore,  Alternative  3 may  be  implementable,   but based on
historical  data,  the  efficiency  of  remediating  this  type of
 contamination is questionable.

 Coat

Alternative 2 at a cost of $1.5 million, provides the  same amount
 of information as Alternative 3  (approximate cost $6 million) with
 respect  to characterization of  contaminant   level  reductions.
Alternative 2  does not  achieve reductions in contaminant levels in
the  same  time frame   as the  recovery  and  treatment  of  the
 contaminant plume under Alternative 3.  Alternative 2 can be


                               64

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implemented  for  a  significantly  reduced cost  and provide  the
flexibility  to continue  assessment  of ground  water contaminant
levels.

State Acceptance

The State of Oklahoma believes that ground water monitoring is the
appropriate  alternative for this  site.  Attachment C is a letter
from the ODEQ to the EPA stating that the State of Oklahoma concurs
with the Limited Action alternative.
Community Acceptance

Comments received during  the  public comment period indicate that
much  of  the community questioned  whether the Proposed  Remedy -
Limited Action, was protective of human health and the environment.
One commenter provided written opposition to the proposed remedy,
and   suggested  the   use  of   a   specific   technology  termed
"bioremediation  and  metals extraction".   All comments  received
during the  public  comment period,  and EPA responses are  in the
attached Responsiveness Summary (Attachment B).


X. THE SELECTED REMEDY

Based  upon  consideration of  the  requirements  of  CERCLA,  the
detailed analysis of the alternatives using the nine criteria, and
public comments,  the  EPA has  determined that  Alternative 2  -
Limited Action  is the most appropriate  alternative for remediating
the  ground  water  beneath  the Double Eagle  site.    The  major
components of this remedy include:

     Installation of warning signs to require notification prior to
     drilling in the area.

     A deed notice  filed to notify future land  owners of  the
     hazards associated with the contaminated ground water in the
     area of the site.

•     Installation of  additional  deeper monitoring wells further
     down-gradient to ensure  that contaminants do not migrate
     deeper, or to a receptor point off site,  and to determine if an
     offsite source of contamination exists.

•     Establishment of a routine (quarterly sampling for the first
     two  years, then semi-annually for  the following three years)
     monitoring and maintenance program for ground  water  sampling
     and   modeling  to  evaluate   contaminant  level  reductions
     following removal of  the contaminant source.

     Routine inspections   to ensure that public use of the  upper
     zone of the Garber-Wellington  Aquifer does not occur prior to

                               65

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     attainment of the remedial action objectives.

     Five-Year review of the site to determine if further actions
     need to be taken with regard to the ground water.  As part of
     the 5-year review, data analysis and ground water modeling is
     included  to  assess  the  adequacy  of  the  monitoring  and
     maintenance plan.

     Contingency measures (which include active treatment) that can
     be  implemented  if the ground  water monitoring indicates an
     increase in contaminant concentrations (either vertically or
     horizontally).  The contingency measures are described below.

EPA  believes that  the  Limited Action alternative is the  most
appropriate alternative for the following reasons:

1)  The ground water in the vicinity of the site is not used as a
water supply;

2)  The extremely high concentration of Total Dissolved Solids make
the ground water undesirable as a water supply source;

3)  Efforts to remove site-related contaminants in the ground water
would not improve its over all quality, and;

4)  The North Canadian River is not threatened at the present time,
nor will it be threatened in the future by site contaminants.

The primary threat posed by  the contaminated  ground water is the
possibility  of  migration  of the  contamination  downward  into  a
useable drinking water zone,  or lateral migration into a surface
water  body which  is  the  North Canadian river.    EPA  considers
Alternative 2 the most prudent remedy in light  of the fact that the
upper portion of  the Garber Wellington aquifer and the alluvial
aquifer are considered  Class III aquifers.  Also, the data obtained
during  the  investigation  stage  of the  project  suggests  the
possibility  of  an offsite,  upgradient source of  contamination.
Since the Total Dissolved Solids in the ground water are so high,
and there is a possibility of an offsite source  of contamination,
even  if  a  pump  and  treat  alternative  (Alternative  3)   was
implemented at a  much  higher cost, the ground water  would still
remain non-useable.

The  goal  of  the  remedial  action is  to prevent  migration  of
contaminants from the shallow aquifer to the  deeper aquifer,  thus
maintaining the deeper aquifer  for its beneficial use.   Based on
information obtained during the remedial investigation and analysis
of  all  remedial  alternatives,  EPA  believes  that  the  preferred
remedy is the most appropriate  alternative to achieve this goal.
If monitoring does not indicate a reduction in the concentration of
ground water contamination or if the ground water plumes continue
to expand based on sampling of the specified monitoring points, the
contingency measures described below may be implemented.


                                66

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 The  preferred  remedy  is protective  of  human  health  and  the
 environment, complies with Federal and State requirements that are
 legally  applicable or  relevant  and appropriate  to the  remedial
 action,   and  is  cost-effective.     Because  treatment  of  the
 contaminated ground water was not  found to be warranted at this
 time,  this remedy does not  satisfy the  statutory preference  for
 treatment as a principal  element of the remedy.

 Because   the preferred  alternative" will   result   in  hazardous
 substances remaining on-site  above health based  levels (in  the
 shallow ground water, including the alluvial and upper portion of
 the Garber-Wellington aquifers),  a review will  be conducted within
 five years after commencement of remedial action to ensure that the
 remedy continues to provide adequate protection of human health and
 the  environment.   All  work  to be performed at the site will be
 conducted pursuant  to 29  CFR Part 1910 (Worker health and Safety
 Plan).


 Contingency measures;

 The  preferred  alternative  provides for  natural  attenuation to
 reduce contamination levels in the  alluvial aquifer and the  upper
 portion of the  Garber-Wellington  aquifer, and to prevent migration
 of contaminants from the alluvial aquifer and the upper portion of
 the Garber-Wellington aquifer to  the deeper  portion  of the Garber-
 Wellington  aquifer.   The  alternative  also  provides  for ongoing
 monitoring  of  all  existing  site wells  to determine  1)  whether
 natural attenuation is working to reduce the contamination level in
 the ground water aquifers,  and 2)  whether  the contamination has
 migrated vertically or horizontally.

 If  during  the  monitoring,   detectable  concentrations  of  site
 contaminants are found  below  the  affected upper portion of the
 Garber-Wellington aquifer, or if the contaminated portions of the
 ground water show an increase of  30  percent  for any contaminant in
 any of the alluvial  or  upper Garber-Wellington monitoring wells;
 the  well   which  showed  the   increase  in  concentration  will  be
 resampled immediately.   If the second analysis confirms that there
 has been  a 30  percent  increase in  contaminant concentration, or
 resampling  of  the  deeper  Garber-Wellington  aquifer  confirms
 detection, EPA  will  evaluate  1) the  impacts  of any offsite sources
 of contamination, and 2) the need for additional remedial action to
 address site related contaminants.  Based on  these evaluations, EPA
may require implementation of  any or all of the  following actions:

     •    Installation of additional monitoring wells to determine
          if the contamination is increasing in  concentration or
          migrating.

          Increasing the  frequency  of  sampling to  assure that a
          complete exposure pathway does  not develop.
                               67

-------
      •     Construction  of a containment measure such as a slurry
           wall.

      •     Implementation  of a remedial action plan for extraction,
           treatment,  and  disposal of  contaminated  ground water.

The decision to implement contingency measures may be outlined in
an  Explanation  of  Significant Difference,  that  will be  made
available  to the public in the Administrative Record.

Alternative  2  will  provide protection  to  human  health  and the
environment by allowing  the  EPA to monitor the  ground water to
confirm  contaminant level reductions  (as predicted),  and ensure
that  contaminant migration does  not reach a receptor point.

Alternative 1  is not  considered  appropriate since  the "No-Action"
alternative  will  not allow  monitoring of  the ground  water to
provide  protection to human health and the environment.

Since the  data suggests the possibility of  an  offsite source of
contamination,  and  the  industrialized  nature  of the adjacent
properties, an investigation is currently being  conducted by other
programs within both the State and the EPA which have authority to
address  a  health threat posed by petroleum  products  from active
facilities  that   are  exempt  under   Superfund.     A  Resource
Conservation   and  Recovery  Act  (RCRA)   inspection  of  active
facilities in  the  area  is underway.   If it  is discovered that an
unauthorized  release has occurred,  appropriate  action will be
taken.

XL THE STATUTORY DETERMINATIONS

EPA's primary  responsibility  at Superfund  sites  is  to  select
remedial actions  that  are protective  of human  health and the
environnent. Section 121  of CERCLA also requires that the selected
remedial action for the  site comply with applicable or relevant and
appropriate environmental  standards established under Federal and
State environmental laws,  unless  a waiver is granted.  The selected
remedy  must also  be cost-effective  and utilize treatment  or
resource recovery technologies to the maximum extent practicable.
The statute also contains a preference for  remedies that include
treatment as a principal element.  The following sections discuss
how the  selected remedy for contaminated ground water at the DER
site meets the statutory requirements.

Protection of Human Health and the Environment

The future use scenario  is  the  only complete  pathway  for human
exposure to the contaminant plume.   Exposure under this scenario
would be completed  if  a 60-foot deep public drinking water well was
installed  at  the  site boundary  and  within  the area  of  the
contaminant plume.  Alternative 2 provides control of this exposure
route by reducing the  likelihood that a drinking  water well will be

                                68

-------
 installed prior to attainment of the  remedial  action objectives.
 Based on the worst-case  natural attenuation modeling  results,  a
 period of 60 to  150  years is expected before  contaminant levels
 will attenuate  to within the remedial action objectives.  However,
 based on levels of TDS at the exposure point,  it is unlikely that
 the upper portion of  the  bedrock aquifer  will  be used as a public
 drinking water  source.

 The monitoring  and maintenance program will be used to demonstrate
 attenuation   of   contaminant  levels  and  provide   sufficient
 information to  conduct regular ground water modeling.  Based on the
 results  of routine monitoring and ground water modeling results,
 the site controls  and monitoring and  maintenance plan would  be
 revised  as necessary.

 A minimum degree of  cross-media  impacts  or short-term  risks  are
 associated with this  alternative  since additional exposure to  the
 contaminated media is minimized.   Therefore, to the extent that  the
 upper portion  of the bedrock  aquifer is  not used  as a  public
 drinking water  source,  this alternative provides a high degree of
 protection to human health and the environment.   Through  natural
 attenuation,  contaminant  levels  are  expected  to  be within  the
 remedial action objectives at a future time.  If the  ground water
 is  used  as a  public drinking water source, this  alternative does
 not eliminate the risk  to  human health and  the  environment during
 the period that natural attenuation of contaminant levels  occurs
 and contaminant levels  exceed the remedial  action objectives.

 Compliance with ASARs

 The ground water  at the exposure  point  is not currently  used as a
 public drinking water source due to the high total dissolved solids
 from past oil production  activities.   Continued monitoring will
 monitor  the  attenuation  of  contaminant  levels to MCLs.    Since
 modeling results indicate that  the contaminant  plume  will not
 impact the river, the potential ARARs associated with surface water
 standards  will  be  achieved.    Additional  action-specific  ARARs
 associated  with   implementation   of  this  alternative   include
 standards  for  installation of  additional wells  and  disposal  of
 miscellaneous wastes associated with the monitoring program such as
 sampling equipment and  produced water.    Those wastes  will  be
 properly disposed of in an appropriate  facility  in compliance with
 the  EPA's offsite disposal policy.  Compliance with the action-
 specific ARARs is not expected to present a significant obstacle to
 implementation of this remedial alterative.  Action-specific ARARs
 are  listed in Table 18.

Cost-Effectiveness

The selected remedy is considered cost effective since it is much
less expensive than Alternative 3, yet provides adequate protection
to human health and the environment.   The "No-Action" alternative
                                69

-------
is  not considered acceptable  since it provides  no protection to
human  health  and  the environment.

Utilization of Permanent Solutions and Treatment or Resource Recovery Technologies to the
Maximum Extent Practicable

Alternative 2 is not considered permanent because this alternative
will not actively remove the contamination within the aquifer and
restore the  ground water to MCLs.   Alternative 2  does  not use a
treatment technology or a resource recovery technology as an aspect
of  this remedy.   However, it is  considered the  most  practical
solution since this alternative will allow continued monitoring, to
confirm whether an off site source of contamination exists, and that
the  classification  of  the aquifer  as a  Class III  zone  remains
appropriate.

Alternative 2 is  considered permanent in the sense that the five-
year review  will allow ground water  sampling and analysis,  and
modeling to confirm  contaminant  level reductions; and if a future
threat to human  health and  the  environment becomes  apparent,
Alternative  3 or a  comparable  pump and  treat operation  can be
implemented at that  time.

Preference for Treatment as a Principal Element

Treatment is not a principal element of alternative 2; however, it
is  considered  the  best  alternative  considering the  specific
conditions and circumstances at  the site.


XII. DOCUMENTATION OF SIGNIFICANT CHANGES;

The  overall   remedy  selected  in this  ROD  is not significantly
different  from  the  alternative  proposed  for  public  comment.
However,  a  contingency  plan  for  future  evaluation  of  active
remediation, should the lower Garber-Wellington aquifer be impacted
by contaminants from the DER site,  has been included.
                                70

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ADMINISTRATIVE RECORD INDEX
           FINAL
SITE NAME:    DOUBLE EAGLE REFINERY SITE
SITE NUMBER:  OKD 980696470
INDEX DATE:   03/03/94

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*****************************************************************************
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*****************************************************************************
*                           I. CHRONOLOGICAL LISTING                          *
                                                                            t**
                                                                            Ir**
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                  ADMINISTRATIVE RECORD INDEX
                             FINAL
SITE NAME:
SITE NUMBER:
DOUBLE EAGLE REFINERY SITE
OKD 980696470
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005598 - 005625
10/27/92
028
Staff Consultants
Fluor Daniel, Inc.
U.S. EPA Region 6 Site Files
Final Project Work Plan
"Final Project Work Plan for the Groundwater Operable Unit
Remedial Investigation/Feasibility Study  (RI/FS)  - Volume 1'
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005626 - 005851
01/01/93
226
Staff Consultants
Fluor Daniel, Inc.
U.S. EPA Region 6 Site Files
Final Work Plan
"Final RI/FS Work Plan for Groundwater Operable Unit"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:

COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005852 - 005867
01/12/93
016
Robert K. Franke, ARCS Project Manager and Mark L. deLorimier,
P.E., ARCS Program Manager
Fluor Daniel, Inc.
Philip Allen, Remedial Project Manager, U.S. EPA Region 6
Correspondence and Attachment
"Responses to Region 6's and Oklahoma State Department of
Health's comments regarding the Final RI/FS Work Plan"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005868 - 005868
02/18/93
001
EPA Staff
U.S. EPA Region 6
U.S. EPA Region 6 Site Files
Open House Invitation
"Invitation to the public to attend the 02/18/93 open house to
learn more about Superfund activities at the Double
Eagle/Fourth Street Superfund Sites"

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                  ADMINISTRATIVE RECORD INDEX

                             FINAL
SITE NAME:
SITE NOMBER:
DOUBLE EAGLE REFINERY SITE
OKD 980696470
DOCUMENT NOMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:

COMPANY/AGENCY:
RECIPIENT:

DOCUMENT TYPE:
DOCUMENT TITLE:
005869 - 005879
12/24/92
Oil
Robert K. Franke, ARCS Project Manager and Mark L. deLorimier,
P.E., ARCS Program Manager
Fluor Daniel, Inc.
Philip H. Allen, Remedial Project Manager (RPM),  U.S. EPA
Region 6
Correspondence and Attachments
"Bedrock Monitoring Well Data - Double Eagle and Fourth Street
Refinery Sites"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005880 - 005880
02/03/93
001
Philip H. Allen, P.E., RPM
U.S. EPA Region 6
Robert K. Franke, ARCS Project Manager, Fluor Daniel, Inc.
Correspondence
"Modelling Assumptions for the Risk Assessment for the Ground
Water Operable Unit at the Double Eagle and Fourth Street
Refinery Sites"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005881 - 005886
02/23/93
006
Philip H. Allen, P.E., RPM
U.S. EPA Region 6
Robert K. Franke, ARCS Project Manager, Fluor Daniel, Inc.
Correspondence and Attachments
"Guidance for the Risk Assessment and the Remedial
Investigation/Feasibility Study  for the Ground Water Operable
Unit - Double Eagle and Fourth Street Refinery Sites"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:

COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005887 - 005890
02/26/93
004
Robert K. Franke, ARCS Project Manager and Mark L. deLorimier,
P. E., ARCS Program Manager
Fluor Daniel, Inc.
Philip H. Allen, RPM, U.S. EPA Region 6
Correspondence and Attachments
"Updated Project Schedule - Double Eagle and Fourth Street
Refinery Sites"

-------
                  ADMINISTRATIVE RECORD INDEX
                              FINAL
 SITE NAME:
 SITE NUMBER:
DOUBLE EAGLE REFINERY SITE
OKD 980696470
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
005891  -  006450
07/27/93
560
Staff Consultants
Flour Daniels, Inc.
U.S. EPA  Region 6 Site Files
Final Remedial Investigation Report
"Ground Water Operable Unit Final Remedial Investigation
Report  -  Double Eagle Superfund Site"  (Includes Appendixes
A-K)
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
006451  -  006917
07/27/93
467
Staff Consultants
Fluor Daniel, Inc.
U.S. EPA  Region 6 Site Files
Final Feasibility Study Report
"Ground Water Operable Unit Final Feasibility Study Report
Double Eagle Superfund Site"  (Included Appendixes A-E)
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:'
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
006918  - 006932
08/05/93
015
EPA Staff
U.S. EPA Region 6
General Public
Proposed Plan of Action
"EPA Announces Proposed Plan of Action"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
006933 - 006933
03/31/89

Office of Emergency and Remedial Response
U.S. EPA - Washington, D.C.
U.S. EPA Region 6 Site Files
Guidance Document
"Risk Assessment Guidance for Superfund: Volume 2 -
Environmental Evaluation Manual  (Interim Final)".
EPA/540/1-89/001, March 1989.   (See "For Your Information")

-------
                  ADMINISTRATIVE RECORD INDEX
                             FINAL
SITE NAME:
SITE NUMBER:
DOUBLE EAGLE REFINERY SITE
OKD 980696470
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
006934 - 006934
12/31/89

Office of Emergency and Remedial Response
U.S. EPA - Washington, D.C.
U.S. EPA Region 6 Site Files
Guidance Document
"Risk Assessment Guidance for Superfund: Volume 1  - Human
Health Evaluation Manual (Part A)  (Interim Final)".
EPA/540/1-89/002, December 1989.   (See "For Your Information")
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
006935 - 006935
12/31/91

Office of Emergency and Remedial Response
U.S. EPA - Washington, D.C.
U.S. EPA Region 6 Site Files
Guidance Document
"Risk Assessment Guidance for Superfund: Volume 1-Human Health
Evaluation Manual (P^rt B, Development Risk-based Preliminary
Remediation Goals (Interim)".  Publication 9285.7-01B, Dec.
1991.  (See "For Your Information")
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
006936 - 006936
12/31/91

Office of Emergency and Remedial Response
U.S. EPA - Washington, D.C.
U.S. EPA Region 6 Site Files
Guidance Document
"Risk Assessment Guidance for Superfund: Volume 1  - Human
Health Evaluation Manual (Part C, Risk Evaluation  of  Remedial
Alternatives) (Interim)".  Publication 9285.7-01C, December
1991. (See "For Your Information")
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
006937 - 006967
02/28/92
035
Office of Emergency and Remedial Response
U.S. EPA Headquarters - Washington, D.C.
U.S. EPA Region 6 Site Files
Summary Report - Volume 1
"Evaluation of Ground-Water Extraction Remedies:  Phase II1

-------
                  ADMINISTRATIVE RECORD INDEX
                             FINAL
SITE NAME:
SITE NUMBER:

DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
DOUBLE EAGLE REFINERY SITE
OKD 980696470

006968 - 007417
02/28/92
450
Office of Emergency and Remedial Response
U.S. EPA Headquarters, Washington, D.C.
U.S. EPA Region 6 Site Files
Case Studies and Updates  - Volume 2
"Evaluation of Ground-Water Extraction Remedies: Phase II'
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
         TITLE:
007418 - 007547
06/30/92
130
Staff Consultants
Fluor Daniel, Inc.
U.S. EPA Region 6 Site Files
Draft Remedial Investigation
"Draft Remedial T-vnstigation Phase III Report"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
007548 - 007589
03/29/93
042
Unspecified
U.S. EPA Region 9
U.S. EPA Region 6 Site Files
Compendium of Guidance Documents Index
"Compendium of CERCLA Response Selection Guidance Documents
Index"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
007590 - 007628
08/12/93
039
Lena Pierce, Court Reporter
National Records Service of Dallas
U.S. EPA Region 6 Site Files
Public Meeting Transcript
"Transcript of public hearing held on 08/12/93 at 7:00 p.m.,
YWCA, McFarland Branch Auditorium, Oklahoma City, OK"

-------
                  ADMINISTRATIVE RECORD INDEX
                             FINAL
SITE NAME:
SITE NUMBER:

DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
DOUBLE EAGLE REFINERY SITE
OKD 980696470

007629 - 007634
09/03/93
006
Matthew Biddle, Department of Geography
University of Oklahoma - Norman, OK
Melanie Ontiveros, D.S. EPA Region 6
Public Comment Letter
"Comments on the proposed plan"
DOCUMENT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:
COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
007635 - 007653
09/04/93
019
Phillip Reeves, President
Enviro-Energy
Melanie Ontiveros, U.S. EPA Region 6
Public Comment Letter and Enclosures
"Comments on the proposed plan"
DOCUMECT NUMBER:
DOCUMENT DATE:
NUMBER OF PAGES:
AUTHOR:

COMPANY/AGENCY:
RECIPIENT:
DOCUMENT TYPE:
DOCUMENT TITLE:
007654 - 007656
10/04/93
003
LeAnne Burnett, Attorney representing the Double Eagle PRP
Group
Crowe & Donlevy
Philip Allen, RPM, U.S. EPA Region 6
Public Comment Letter
"Comments regarding the Record of Decision for Operable Unit
2"

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                          ATTACHMENT B
                   THE RESPONSIVENESS SUMMARY

 The  Responsiveness Summary has been prepared to provide  written
 responses  to comments  submitted  regarding the Proposed  Plan  of
 Action  at  the Double  Eagle Refinery  (DER)  Superfund site.   The
 summary is divided into two sections.

 Section I: Background  of  Community  Involvement and  Concerns.  This
 section provides a brief history of community interest and concerns
 raised during the  remedial  planning activities at the DER  site.

 Section II: Summary of Ma~ior Comments Received. The  comments (both
 oral and written)  are  summarized and EPA's  responses  provided.

 7. Background of Community Involvement and Concerns

 Interest  in  the  DER  site  on the  part  of the residents,  local
 government officials,  and potentially responsible parties (PRPs)
 has been moderate.  Community relations activities were  initiated
 in 1989 when the  site  was proposed for inclusion on  the National
 Priorities List.   A Community Relations Plan (CRP) was developed in
 Dec. 1989, and the final  published and released to the  public  on
 Jan.  26,  1990.   The  CRP was prepared  to identify  and  address
 community concerns raised during the original  RI/FS for  the SCOU.
 Copies of the CRP  are located in the information repositories. The
 CRP  identified that the  primary interest  in the  DER site  lies
 mostly with the residents who live near the site.  Also,  several
 PRPs have come  forward  concerning the DER site as discussed  in this
 Record of Decision.

//. Summary of Major Comments Received

 Public notice announcing the public comment  period and opportunity
 for a public meeting was printed in The Black  Chronicle  on August
 5, 1993. The proposed plan  fact sheet was also distributed to the
 site mailing list on August 5, 1993, and a reminder was  published
 on August  12,  1993 in The Black Chronicle.   An open house was
 conducted the  evening  of August  12, 1993,  to inform the  public
 about the Remedial Investigation and Feasibility Study Reports and
 the Proposed  Plan  of Action.  The comment period began on  August 5,
 1993, and was scheduled to end on September  4,  1993.   An  extension
 to the  public  comment  period was  granted  (per  the  PRP  group's
 request)  which extended the comment period until October 7,  1993.
At the meeting, EPA and ODEQ officials discussed the contamination
problems  associated  with  the  ground  water  beneath the site,
presented the various remedial alternatives that were  considered,
and presented the preferred  alternative to address the  ground water
contamination at the DER site.

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Approximately 20  people were  in  attendance at the meeting.
The  public was  given the  opportunity  to  make comments  or  ask
questions.  Seven people made comments or asked  questions.  A full
account  of the public meeting can be found in the public meeting
transcript which  is documented in the DER Administrative Record.

      a)  Verbal Comments

The comments/questions received orally during the public meeting on
August 12,  1993 are as follows:

Comment:

The  commenter asked  if she could obtain copies  of the overhead
transparencies that  were used  during  the  presentation  at  the
beginning  of  the  Public meeting.

Response:

The commenter was provided copies of the transparencies at the end
of the meeting the night  of August 12,  1993.

Comment:

The  commenter  stated that she  missed  the  introduction  of  the
speaker  that presented information at the beginning  of  the meeting
and would  like to know whom he was.

Response:

The speaker was Philip Allen,  the Remedial Project Manager for the
Double Eagle  site.

Comment:

The commenter stated  that five other NPL sites are present in the
area; and that EPA investigates these sites separately.   Since all
of these sites are located above the Garber Wellington aquifer,  the
commenter expressed concern of migration of contaminants from all
the sites into the aquifer.  The  commenter further stated that the
sites need to treated as  a  Regional  problem,  with respect to  the
overall effect in the  long term of all these sites on the.aquifer.

Response:

The EPA  has conducted investigations at all  NPL sites within  the
Oklahoma City area.   The results of these investigations indicate
that there is no  overlap  of the contaminant plumes; therefore no
cumulative effects which would result in additional  risk to human
health and the environment  are  evident.  It  should be noted that
the  Double  Eagle  and Fourth   Street   sites  were  investigated
simultaneously due to their proximity to each other.

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 Comment:

 The commenter expressed  concern that the Proposed  Plans  for the
 Double Eagle and Fourth Street were almost identical, and asked if
 the sites were similar enough to produce two documents so similar.

 Response:

 The Double Eagle and Fourth Street sites are very  similar.   The
 types of  operations conducted at the sites, the type of waste, and
 the contaminants  found in the waste  are all so  similar that the
 documents are also very  similar.  These  facts  coupled with the
 close proximity  of the sites resulted in the EPA using the  same
 contractor  to conduct the  investigations,  and allowed  a  cost
 savings to  the  Government,  since  duplication  of  efforts  were
 minimized.

 Comment:

 The commenter asked what  long term effect will these sites have on
 the North Canadian River  and future use of the  river.

 Response:

 The results of the Remedial Investigation indicate that there will
 be  no adverse impact on the North Canadian River as a result of any
 migration of  contaminants from the  Double  Eagle site.

 Comment:

 The commenter asked what was  anticipated for the future land use of
 the sites once the remedial action was complete for the source.

Response:

When  the remedial  action  is complete for  the  Source  Control
 Operable  Unit,  the  land  use  is anticipated  to continue to  be
 industrial use.   There will also be  a deed notice placed on the
deed to notify any potential  future land owners of the ground water
contamination.

Comment:

The commenter asked if there are any viable PRPs  on  the  sites.

Response:

There are several viable  PRPs for the  DER site, and  a group of 22
participating PRPs  have  made a settlement offer;  however,   the
negotiations are ongoing,  and the PRP  search is continuing.

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     b)  Written  Comments

The comments  received  in writing during the public comment period
are as  follows:

Comment:

The commenter wrote  that there was  no North arrow or scale on the
map provided  in the Proposed Plan;  and that the abbreviations were
confusing.

Response:

The direction North  would be pointing straight up on the page and
the map is not to exact scale.  Additional maps are provided in the
Record of Decision with North arrows and scales.  The abbreviation
"IH" implies  Interstate Highway.

Comment:

The Proposed Plan on page 1 identifies the railroad adjacent to the
site as "Union  Pacific" while  the map on page  3  uses Santa  Fe
(ATSF) .

Response:

The railroad  lines are  essentially  identical,  and ATSF  stands for
Atchinson, Topeka and Santa Fe Railroad.

Comment:

The commenter wrote  that it is not  clear how or why EPA considers
lead the "major" contaminant of concern.

Response:

Lead is  the  contaminant that provided  the greatest risk  for the
Source Control Operable Unit.

Comment:

The commenter wrote that the EPA fails to provide justification for
the choice of Alternative 2 in the  Proposed Plan.

Response:

The EPA proposed the Limited Action  alternative (Alternative 2)  in
the Proposed Plan on August 5, 1993.  The Proposed Plan is intended
to be  a brief outline  of  the rationale for proposing  a  remedy.
Further discussion of the rationale and justification is provided
in the  Record of Decision.  EPA believes that  the Limited  Action

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 alternative  is  the most appropriate alternative for the following
 reasons:

 1)   The ground  water in the vicinity of the site is not used as a
 water supply;

 2)  The extremely high concentration of Total Dissolved Solids make
 the ground water undesirable as a  water supply source;

 3)  Efforts to remove site-related  contaminants in the ground water
 would not improve its over all  quality,  and;

 4)  The North Canadian River is  not threatened at the present time,
 nor will it  be  threatened in the future by  site contaminants.

 Comment:

 The  commenter  wrote  that  the  section  in  the  Proposed  Plan
 discussing ARARs is "vague and ambiguous",  and  "does not  clearly
 indicate if  the chosen alternative actually does comply with Safe
 Drinking Water  Act or Clean Water  Act provisions".

 Response:

 The ground water at the exposure point  is not  currently used as a
 public drinking water source due to the high total dissolved solids
 from past  oil production  activities.   Continued monitoring  will
 monitor the  attenuation  of contaminant levels to  MCLs.    Since
 modeling  results  indicate that the contaminant plume will not
 impact the river, the potential  ARARs associated with surface water
 standards  will  be achieved.   Additional  action-specific ARARs
 associated   with  implementation  of  this  alternative   include
 standards  for installation  of  additional  wells  and disposal  of
 miscellaneous wastes associated with the monitoring program such  as
 sampling  equipment  and produced  water.    Those wastes  will  be
 properly disposed of in an appropriate facility in compliance with
 the EPA's  offsite disposal policy.   Compliance with the  action-
 specific ARARs is not expected to present a significant obstacle  to
 implementation of  this  remedial  alterative.

 Comment:

 The commenter wrote that it appears that the EPA's position is that
 a primary advantage of Alternative 2 is that it can be implemented
 quickly.

Response:

 EPA disagrees with the comment.  The  "Limited Action" alternative
 is  consistent   with Superfund  guidance regarding  ground water
remedies in  areas of high Total Dissolved  Solids.   EPA believes
that the ground water in the area  of the Double Eagle site would

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remain unusable  after the removal  of  site  related contaminants.
Although  time  to implement  a remedy  is  a consideration  in the
selection process,  the  effectiveness of  restoring a ground water
resource is also considered.

Comment:

The commenter stated that Alternative 2 is a low cost approach, and
cost is not the primary criteria.  The commenter requested that the
EPA consider "bioremediation and metals extraction" and requested
an opportunity to present his technology.

Response:

Cost  is  only  one  of  nine criteria  considered  in  the  remedy
selection  process,   and  is  not considered  one  of the  primary
criteria.  Effectiveness in  reducing risk,  however,  is a primary
criterion.  Because the  more costly "pump and treat" alternative
would not be any more; effective  in the  long term than attenuation,
in  reducing the  risk from  use of the  upper Garber-Wellington
(bedrock) aquifer,  EPA does not  believe that Alternative  #3  is
cost-effective.  Since a "pump and treat"  system is not considered
a prudent remedy at  the DER site  for the contamination  in the
ground water,  a  demonstration of the  "bioremediation  and metals
extraction" technology is not being considered at this time.

Comment:

The commenter  wrote  that  the  EPA did  not give  the public  an
adequate  opportunity to review essential  information  regarding
Operable Unit 2 prior to the Public meeting on August 12, 1993; and
the  RI/FS  reports  were  not  available  at  the  information
repositories prior to the meeting.

Response:

The public was given ample time to review the RI/FS reports prior
to the public meeting, and was given an extension to the normal 30
days.   The EPA  extended the comment period which allowed the public
a total of 64 calendar days to review all documents pertaining to
the site and  submit written  comments.    Attachment  1 to  this
Responsiveness   Summary    includes   2    Document   Transmittal
Acknowledgement Forms.  One  of  the  Acknowledgement forms  is from
the Ralph Ellison Branch library and the other  is from the Oklahoma
State Department of Health.

Comment:

The commenter wrote that no specific monitoring requirements are
proposed  under the remedial action  plan, and that  a list  of
monitoring  requirements  should be made available  for  public
comment.

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 Response:

 The major components of  the selected remedy are outlined  in the
 Record of  Decision.   The  Limited  Action alternative  includes
 quarterly ground water  monitoring for the first two years,  and
 semi-annually monitoring for  the following  three years.    The
 specific  contaminants that will be analyzed for during monitoring
 will be determined during Remedial Design.

 Comment:

 The commenter wrote that data  from the ground water RI/FS  study
 show that the  Double Eagle  site is hydraulically  lower and  is
 impacted  by polluted ground  water from upgradient of the  Double
 Eagle site;  and remediation of any ground water  contamination
 coming from  upgradient of the Double  Eagle  site should not  be the
 responsibility  of  the Double Eagle PRPs.

 Response:

 The RI/FS states that there is a possibility of an off-site  source
 of  contamination but was  not conclusive.  The contamination  in the
 ground water beneath  the  Double Eagle site  is attributable to the
 surface  contamination,   for which  the  PRPs   are  responsible.
 Therefore, the  PRPs are responsible for the ground water Remedial
 Design and  Remedial  Action  for the  Selected Remedy  - Limited
 Action.

 Comment:

 The commenter wrote  that part  of  the  proposed  Operable  Unit 2
 remedial design for the Double Eagle and Fourth Street sites  is to
 install 11  ground  water  monitoring wells;  and  that there was no
 clear  indication if  this means 11 wells total or  11  per  site.
 Regardless, since the ground water is impacted by ground water from
 upgradient  of  the site,  no responsibility for installing and
 maintaining  monitoring wells on or around  the  Double Eagle  site
 should be placed on the Double  Eagle PRPs.

 Response:

 The Feasibility Studies for the  subject sites estimated 11 wells to
 be installed during remedial action per  site. However, the amount
 of  wells  actually  necessary  to ensure  that no  future  threat to
human  health and  the environment  is  posed by  the contaminated
 ground water, is a design consideration and the final determination
will be made during remedial design.   Since the installation of
these  wells   and  the subsequent monitoring and maintenance is
necessary  due  to  the  activities  at  the  site,  the  PRPs are
 responsible for this aspect of the site remediation.

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 Comment:

 The  commenter wrote  that lead  levels in  the ground  water  are
 already  below the clean up goals;  and EPA  should provide to  the
 public not only clean up goals for the contaminants of concern,  but
 also the current levels of contaminants in the ground water.   By
 providing only the list of  contaminants of  concern and  cleanup
 levels,  EPA infers that each of those contaminants is above  the
 cleanup  level.  This  is  not the case.

 Response:

 The Proposed  Plan  contained the original contaminants of concern.
 The final contaminants of concern and the Remedial Action Goals  are
 provided in the ROD.

 Comment:

 The commenter wrote that manganese  is  not a "hazardous substance"
 as set  forth  in Sections 101(14)  and  102 (a)  of CERCLA or 40  CFR
 Part 302; consequently, EPA does not have jurisdiction under CERCLA
 to designate  this  compound as  a  "constituent of concern" at this
 site, and thus EPA has no authority to establish cleanup goals in
 the Proposed  Plan  for this substance.

Response:

Manganese is  not a hazardous substance as  set forth in Sections
 101(14)  and 102(a) of CERCLA or 40  CFR Part  302.  However, Section
 104(a)(l)(B)  states   that  "Whenever  there  is  a  release   or
 substantial threat of release into the environment of any pollutant
 or contaminant which may present an imminent and substantial danger
to the public health or welfare, the President is authorized to  act
consistent with the national contingency plan, to remove or arrange
 for the  removal  of, and provide for  remedial action relating to
 such hazardous substance, pollutant, or contaminant at any time..."
Therefore, manganese is still considered a contaminant of concern.

Comment:

The commenter wrote that Heptachlor and Aldrin,  among others, have
been listed as contaminants of  concern. Heptachlor and Aldrin  are
not,  however,  typical  ground water contaminants from oil recycling.

Response:

Heptachlor and. Aldrin are  contaminants encountered in the ground
water  at the site  and pose  a  risk to  human  health and   the
environment,  and are therefore contaminants of concern.  However,
Heptachlor and Aldrin are not normally expected to be encountered
as contaminants of concern at oil recycling sites.
                                 8

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 Comment:

 The  conunenter wrote that  all  cleanup levels for  contaminants  of
 concern  are  inconsistent with  the  MCLs.

 Response:

 The  remedial goals  that were  listed in the  Proposed Plan  were
 tentative  goals  based  on information  from the  Source  Control
 Operable Unit.  The final Remedial Action Goals, if a ground water
 restoration system were implemented, are listed  in the ROD in Table
 17.  However, because the alluvial  and upper portion of the Garber-
 Wellington aquifers  are Class  III  aquifers,  these goals  are not
 applicable.

 Comment:

 The commenter wrote that in light  of  the low contaminant  level  in
 the ground water, the  low  quality  of  the area's ground water, and
 the  plans  to remove  the sources of  contamination at the  Double
 Eagle Site,  "no  action" is a more appropriate  and cost effective
 remedial option than EPA's selected "limited action"  remedy.

Response:

 The quality of shallow ground water beneath the Double Eagle  site
has been affected by past oil and gas  production activities in the
area, and the alluvial and upper bedrock aquifers are considered a
Class III zone.   However, in order  to  ensure  to  the public that  no
future threat is posed  by  potential migration of the  site related
contaminants, continued monitoring  and analyses are included in the
Limited Action remedy.  EPA considers  the Limited Action remedy  to
be the most appropriate and prudent action at the  site.

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                                Attachment 1
                      Document Transmittal Acknowledgment
From:
U.S. EPA Region 6
Sent by:     Mava Davis
To:
      of
Ms. Denyvetta Davis
Ralph Ellison Branch Library
2000 N.E. 23rd Street
Oklahoma City, OK 73111
(405) 424-1437
                   _, acknowledge that on this
                                                          ft
                                                             day
            _, 1993,1 received from U.S. EPA Region 6, the second submittal
                                             it'
                                                                                         !
      of the administrative record for the Double Eagle Refinery Superfund Site - Ground

      Water Operable Unit
      [Documents included in the second submittal Ground Water Operable Unit AR
      the July 27,1993 Remedial Investigation, the July 27,
      August 5,1993 Proposed Plan of Action]
                                                                           ;:-:S  -V$&&^:'
                                                                         ^f^^.r^f,^^--
                                                                         /~\ -\1K. S&'rC.,0-..»i-;^,

                                                      ^W/;vW  '* ^&^%^^ftv
      Please return this form to:   Mava Davis, (6H-MQ
                               U.S. EPA Region 6
                               1445 Ross Avenue, Ste. 1000
                               Dailas,TX 75202-2733
                               (214) 655-6484 :
                                                                        •''-?-a?'.-1
     YDPRA File 3732. sos

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                              Document Transmittal Acknowledgment
        From:       U.S. EPA Region 6                    Sent by:      Mava Davis
        To:         Mr. Scott Thompson 0206
                    Oklahoma State Department of Health
                    1000 N.E. 10th Street
                    Oklahoma City, OK 73117-1299
                    (405) 271-7159
. acknowledge that on this  h    day
                                                            is _£	
              of  fvy^j'r     1993, 1 received from U.S. EPA Region 6, the second submittal
                     O
                                                                                    • ",
              of the administrative record for the Double Eagle Refinery Superfund Site - Ground
                                                                                 '.•'.''
              Water Operable Unit                                                .'V-
              [Documents included in the second submittal Ground Water Operable Unit AR are
              the July 27,1993 Remedial Investigation, the July 27,1993 Feasibility Study, and the
              August 5,1993 Proposed Plan of Action]                              |: 4
              Please return this form to:   Mava Davis, (6H-MQ
                                       U.S. EPA Region 6
                                       1445 Ross Avenue, Ste. 1000
                                       Dallas, TX 75202-2733
                                       (214) 655-6484
-•s^A
        cc:    DPRA File 3732. 803

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     AITftCHMENT "C"


MARK S. COLEMAN              W^^S^            DAVID WALTERS
Executive Director                ^3£J;Ji&:      ,        Governor


                          ' State of Oklahoma

             DEPARTMENT OF ENVIRONMENTAL QUALITY


 November  15,  1993

                                                            <=%  g  rn

 Don Williams, Chief                                       "$1  "^ -3
 Oklahoma/Texas  Remedial Section (6H-SR)                    c:  ^
 United  States Environmental Protection Agency              S  _g
 1445 Ross Avenue,  Suite 1200                                02 r£
 Dallas, TX  '/5202-2733                                      ;£  fS
                                                              ^  en
 RE:  Double Eagle  Superfund Site,  Oklahoma City, Oklahoma   Q  &"


 Dear Mr.  Williams:

 My staff and I have reviewed the draft Record of Decision (ROD) for
 the Ground Water Operable Unit for the Double Eagle Superfund Site
 that was  received  by our office on October 25, 1993.  Although  we
 concur with the selected remedy that is  described in the ROD,  we
 cannot  completely  concur with  the site  characterization, ground
 water modeling,  and risk assessment  sections.  The  DEQ does not
'-. believe that the hydrological setting or the extent and degree  of
 ground  water   contamination  has  been   adequately  determined.
 However,  DEQ  does  believe  that enough site  characterization has
 been achieved to choose  the  appropriate remedy for  the site and
 expects the characterization  inadequacies to be solved during the
 Remedial Design.


 Sincerely,
^ Dennis Hrebec, Ph.D., Director
 Superfund Division
                   1000 KorthMM Tenth Stnrt, OkUlxma City. OUahaai 73117-1212

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