f/EPA
          United States        Office of
          Environmental Protection   Emergency and
          Agency           Remedial Response
             Superfund
             Record of Decision:
                                            SEP 191994

                                           EPA/ROD/R06-93/085
                                           September 1993
                                           PB94-964204
>
^

b
             Tinker AFB (Soldier Creek/
             Building 3001), OK

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                   CONCURRENCE DOCUMENTATION

                              FOR THE

      TINKER AFB, SOLDIER CREEK SURFACE WATER AND SEDIMENT
                        RECORD OF DECISION
^  //u
lial Proiei
                                   , i  •	JL
                                   'A  '7/J
                                   / V^.J>C/f y
                          Remedial Project Manager
                             Susan Webster
                             of Regional Counsel
                             Site Attorney
                              enee Holmes
                          sam Becker, Chief
                   Superfund Enforcement Branch (6H-E)
  yn M. Davis, Director
Hazardous Waste Management
Division (6H)
           George Alexander, Jr.
           Regional Counsel (6C)

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                 FINAL
         RECORD OF DECISION
     TINKER AFB - SOLDIER CREEK
    SEDIMENT AND SURFACE WATER
            OPERABLE UNIT
               Prepared for:
         TINKER AIR FORCE BASE
                through
   TULSA DISTRICT CORPS OF ENGINEERS
      CONTRACT NO. DACA56-89-C-0062
               Prepared by:
B&V WASTE SCIENCE AND TECHNOLOGY CORP.
         KANSAS CITY, MISSOURI
            PROJECT NO. 40054
             AUGUST 11, 1993
             Prepared under:
   INSTALLATION RESTORATION PROGRAM
    TINKER PROJECT NO. WWYK89-0196B
         SITE LD. NO. TINKER OT03

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                       RECORD OF DECISION
                            DECLARATION
SITE NAME AND LOCATION
Soldier Creek Sediment and Surface Water Operable Unit
Tinker Air Force Base (AFB)
Oklahoma County, Oklahoma

STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) presents the selected remedial action for the
Soldier Creek Sediment and Surface Water Operable Unit of the Tinker AFB
(Soldier Creek/Building 3001) Site, in Oklahoma County, Oklahoma, 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  is consistent, to the extent practicable,
with the National Oil and Hazardous Substances Pollution Contingency Plan
(NCP).  This decision is based on the Administrative Record file for the operable
unit.

The State of Oklahoma concurs on  the selected remedy. A letter of concurrence
from the State of Oklahoma is presented in Appendix B.

ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this operable unit, if
not addressed by implementing the response selected in this ROD, may potentially
present an endangerment to public health,  welfare, or the environment.  However,
the baseline risk assessment, including a  qualitative environmental assessment,
conducted for the operable unit concluded  that Soldier Creek sediment and
surface water do not pose a risk to human  health or the environment in excess of
the acceptable risk-based exposure levels established by the U.S. Environmental
Protection Agency (EPA).

DESCRIPTION OF SELECTED REMEDY
Soldier Creek Sediment and Surface Water is an operable unit at the Tinker AFB
Site. This ROD addresses the sediment  and surface water contamination
associated with on-base and off-base portions of Soldier Creek.  The first ROD
addressed the Building 3001 Operable Unit and consisted of identifying the
sources of groundwater contamination and  the threat posed by the migration of
this contamination to the groundwater below Building 3001. The first ROD also
addressed Pit Q-51, the North Tank Area, and Water Wells 18 and 19. A
subsequent ROD will address potential groundwater contamination associated with
the Soldier Creek Groundwater Operable Unit.

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A limited action remedy has been selected for the Soldier Creek Sediment and
Surface Water Operable Unit based on the Administrative Record.  The baseline
risk assessment determined that Soldier Creek sediment and surface water do not
pose a risk to human health and the environment in excess of the acceptable
risk-based exposure levels established by EPA.  The remedy selected for the
operable unit incorporates the following components:

     •    Five-year monitoring program of Soldier Creek sediment and surface
          water at on-base and off-base locations.
     •    Ecological investigation (quantitative and qualitative) of Soldier Creek
          sediment and surface water to further define the risk to the
          environment.
     •    Yearly monitoring report.
     •    Five-year review.

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 and alternative treatment technologies to the maximum
extent  practicable for this  operable unit. CERCLA provides a statutory
preference for remedies which use treatment as a principle element of the
remedy. However, as it has been determined that treatment is not necessary, it
will not be used at this operable unit.

This remedy will not result in hazardous substances remaining in the creek
sediment or surface water at concentrations greater than the health-based levels.
A review will be conducted after five years to ensure that the remedy continues to
provide adequate protection of human health and the environment.
Deputy Assistant Secretary of the Air                  Date
Force (Environment, Safety, and
Occupational Health)
Assistant Administrator/Regional Administrator,         Date
U.S. Environmental Protection Agency, Region 6

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A limited action remedy has been selected for the Soldier Creek Sediment and
Surface Water Operable Unit based on the Administrative Record.  The baseline
risk assessment determined that Soldier Creek sediment and surface water do not
pose a risk to human health and the environment in excess of the acceptable
risk-based exposure levels established by EPA. The remedy selected for the
operable unit incorporates the following components:

     •     Five-year monitoring program of Soldier Creek sediment and surface
           water at on-base and off-base locations.
     •     Ecological investigation (quantitative and qualitative) of Soldier Creek
           sediment and surface water to further define the risk to the
           environment.
           Yearly monitoring report.
     •     Five-year review.

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 and alternative treatment technologies to the maximum
extent practicable for this  operable unit.  CERCLA provides a statutory
preference for remedies which use treatment as a principle element of the
remedy. However, as it has been determined that treatment is not necessary, it
will not be  used at this operable  unit.

This remedy will not result in hazardous substances remaining in the creek
sediment or surface water at concentrations greater than  the health-based levels.
A review will be conducted after five years to ensure that the remedy continues to
provide adequate protection of human health and the environment.
  XLAN p.  BABBITT                               Date
  Deputy  for Hazardous Materials
     and Waste
  Deputy  Assistant  Secretary
     of the Air  Force
   (Environment,  Safety and
                    Health)

Assi^nFAdrmnistratr/Regional AdmmistratorjJ        Date
U.S. Environmental Protection Agency, Region 6

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                 TINKER AFB - SOLDIER CREEK
                              FINAL
                     RECORD OF DECISION
                     TABLE OF CONTENTS
DECLARATION	1

ACRONYMS AND ABBREVIATIONS .	 i

1.0  SITE NAME, LOCATION, AND DESCRIPTION	  1-1
    1.1 Site Location and Description  	  1-1
    1.2 Site Demography and Land Use  	  1-1
    1.3 Climatology	  1-4
    1.4 Water Resources	  1-4

2.0  SITE HISTORY	  2-1
    2.1 Previous Investigations and Remedial Activities	  2-1
    2.2 Current Remedial Activities	  2-2
    2.3 Enforcement Activities 	  2-2

3.0  COMMUNITY PARTICIPATION  	  3-1

4.0  SCOPE AND ROLE OF OPERABLE UNIT 	  4-1

5.0  SITE CHARACTERISTICS 	  5-1
    5.1 Sources of Contamination	  5-1
    5.2 Location and Extent of Sediment Contamination	  5-2
       5.2.1  Volatile Organic Contamination  	  5-2
       5.2.2  Semi-Volatile Organic Contamination	  5-6
       5.2.3  Inorganic Contamination	  5-6
    5.3 Location and Extent of Surface Water Contamination 	  5-8
       5.3.1  Volatile Organic Contamination  	  5-8

Tinker AFB - Soldier Creek
Record of Decision               TOC-1

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                  TINKER AFB - SOLDIER CREEK
                                FINAL
                      RECORD OF DECISION
                TABLE OF CONTENTS (Continued)
       5.3.2 Semi-Volatile Organic Contamination	  5-8
       5.3.3 Inorganic Contamination	  5-11
   5.4 Contaminant Characteristics  	  5-11
   5.5 Potential Routes of Migration  	  5-11

6.0 SUMMARY OF SITE RISKS	  6-1
   6.1 Overview of Baseline Risk Assessment	  6-1
   6.2 Contaminants of Potential Concern 	  6-1
   6.3 Toxicity Assessment	  6-2
   6.4 Exposure Assessment  	  6-2
   6.5 Risk Characterization  	  6-9
       6.5.1 Noncarcinogenic Risk	  6-13
       6.5.2 Carcinogenic Risk	  6-13
       6.5.3 Environmental Evaluation	  6-16
       6.5.4 Uncertainties  	  6-19
       6.5.5 Cleanup Goals	  6-20
       6.5.6 Conclusion	  6-20

7.0 DESCRIPTION OF ALTERNATIVES	  7-1
   7.1 SSW Alternative 1-No Action	  7-1
   7.2 SSW Alternative 2-Limited Action 	  7-2
   7.3 SSW Alternative 3-Capping  	  7-3
   7.4 SSW Alternative 4—Sediment  Excavation and Off-Base Landfill
       Disposal  	  7-5
Tinker AFB - Soldier Creek
Record of Decision                TOC-2

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                 TINKER AFB - SOLDIER CREEK
                               FINAL
                      RECORD OF DECISION
               TABLE OF CONTENTS (Continued)
                                                               Page
    7.5 SSW Alternative 5-Sediment Excavation, Stabilization, and Off-Base
       Landfill Disposal	 7-6
    7.6 SSW Alternative 6--Sediment Excavation and Soil Washing  	 7-6

8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES . 8-1
    8.1 Overall Protection of Human Health and Environment  	 8-1
    8.2 Compliance with ARARs	 8-2
    8.3 Long-Term Effectiveness and Permanence	 8-2
    8.4 Reduction of Toxicity, Mobility, or Volume Through Treatment .... 8-3
    8.5 Short-Term Effectiveness	 8-3
    8.6 Implementability	 8-4
    8.7 Cost 	 8-4
    8.8 State Acceptance	 8-5
    8.9 Community Acceptance	 8-5

9.0 SELECTED REMEDY	 9-1

10.0 STATUTORY DETERMINATIONS	  10-1
    10.1  Protection of Human Health and Environment	  10-1
    10.2  Compliance with ARARs	  10-2
    10.3  Cost-Effectiveness	  10-2
    10.4  Utilization of Permanent Solutions and Alternative Treatments . ..  10-3
    10.5  Preference for Treatment  	  10-3

11.0 DOCUMENTATION OF SIGNIFICANT CHANGES	  11-1
Tinker AFB - Soldier Creek
Record of Decision               TOC-3

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              TINKER AFB - SOLDIER CREEK
                         FINAL
                 RECORD OF DECISION
             TABLE OF CONTENTS (Continued)
                                                    Page
APPENDIX A  RESPONSIVENESS SUMMARY
APPENDIX B  STATE LETTER OF ACCEPTANCE
                     LIST OF TABLES

TABLE 2-1   SUMMARY OF PREVIOUS INVESTIGATIONS AND
           ACTIVTrES                                  2-3

TABLE 5-1   CONTAMINANTS DETECTED IN SOLDIER CREEK
           SEDIMENT                                  5-4

TABLE 5-2   TYPICAL BACKGROUND SOIL CONCENTRATIONS    5-7

TABLE 5-3   CONTAMINANTS DETECTED IN SOLDIER CREEK
           SURFACE WATER                            5-9

TABLE 5-4   CHARACTERISTICS OF SELECTED CONTAMINANTS
           OF CONCERN                               5-12

TABLE 6-1   CHEMICAL-SPECIFIC TOXICITY VALUES USED IN
           RISK ASSESSMENT                            6-3

TABLE 6-2   EXPOSURE ASSUMPTIONS                     6-10
Tinker AFB - Soldier Creek
Record of Decision            TOC-4

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              TINKER AFB - SOLDIER CREEK
                         FINAL
                 RECORD OF DECISION
            TABLE OF CONTENTS (Continued)
                                                   Page
TABLE 6-3   SUMMARY OF TOTAL CARCINOGENIC AND
           NONCARCINOGENIC RISKS FOR EACH
           CONTAMINANT OF CONCERN
                           6-11
TABLE 6-4   SUMMARY OF NONCARCINOGENIC RISKS,
           CURRENT LAND USE SURFACE WATER AND
           SEDIMENT EXPOSURES
                          6-14
TABLE 6-5   SUMMARY OF NONCARCINOGENIC RISKS,
           FUTURE LAND USE SURFACE WATER AND
           SEDIMENT EXPOSURES
                          6-15
TABLE 6-6   SUMMARY OF CARCINOGENIC RISKS, CURRENT
           LAND USE SURFACE WATER AND SEDIMENT
           EXPOSURES                               6-17

TABLE 6-7   SUMMARY OF CARCINOGENIC RISKS, FUTURE
           LAND USE SURFACE WATER AND SEDIMENT
           EXPOSURES                               6-18

TABLE 9-1   SELECTED REMEDY COST ESTIMATE             9-5
Tinker AFB - Soldier Creek
Record of Decision
TOC-5

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              TINKER AFB - SOLDIER CREEK
                         FINAL
                  RECORD OF DECISION
             TABLE OF CONTENTS (Continued)
Tinker AFB - Soldier Creek
Record of Decision            TOC-6
                     LIST OF FIGURES

FIGURE 1-1  SITE VICINITY                                1-2

FIGURE 1-2  SITE LOCATION                               1-3

FIGURE 5-1  PHASE I AND II SAMPLING LOCATIONS            5-3

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                ACRONYMS AND ABBREVIATIONS

AFB        Air Force Base
ARAR      Applicable or Relevant and Appropriate Requirement
AWQC     Ambient Water Quality Criteria
CERCLA   Comprehensive Environmental Response, Compensation,
            and Liability Act of 1980
cm2         Square centimeter
cm/hr       Centimeter/hour
COC        Contaminant of concern
EPA        U.S. Environmental Protection Agency
FFA        Federal Facility Agreement
FS         Feasibility Study
HI         Hazard Index
HQ         Hazard Quotient
IWTP       Industrial Wastewater Treatment Plant
kg          Kilogram
L/day       Liter per day
L/kg-day    Liter per kilogram per day
LDR        Land Disposal Restriction
mg/cm2     Milligram per square centimeter
mg/kg       Milligram per kilogram
mg/kg-day   Milligram per kilogram per day
mg/L        Milligram per liter
NAAQS     National Ambient Air Quality Standards
NCP        National Oil and Hazardous Substances Pollution Contingency
            Plan
NA         Not Available
ND         Not Detected
NPL        National Priorities List
O&M       Operation and maintenance
OSHA      Occupational Safety and Health Act
OSDH      Oklahoma State Department of Health
PAH        Polynuclear Aromatic Hydrocarbon
PCB        Polychlorinated biphenyl
ppm        Parts per million
RCRA      Resource Conservation and Recovery Act
RfD        Reference Dose
RI          Remedial Investigation
RME        Reasonable Maximum Exposure
ROD        Record of Decision
SARA       Superfund Amendments and Reauthorization Act of 1986
SSW        Sediment and surface water

Tinker AFB - Soldier Creek
Record of Decision                  j

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ug/L         Microgram per liter
ug/kg        Microgram per kilogram
WQS        Water Quality Standards
Tinker AFB - Soldier Creek
Record of Decision                    ii

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                        DECISION SUMMARY

         1.0  SITE NAME, LOCATION, AND DESCRIPTION
The Tinker Air Force Base (AFB) Site has been divided into three operable units,
Building 3001, which includes the groundwater below Building 3001, the North Tank
Area, Pit Q-51,  and Water Wells 18 and  19; Soldier Creek sediment and surface
water; and Soldier Creek groundwater. This Record of Decision (ROD) addresses
the Soldier Creek Sediment and Surface Water Operable Unit. The Soldier Creek
Sediment and Surface Water Operable Unit is referenced in previous documents as
the Soldier Creek  Site.  A comprehensive discussion  of the site background is
provided in the Remedial Investigation (RI) report.  The RI is  available in the
Administrative Record file at the Midwest City Public Library.

1.1  Site Location and Description
Tinker AFB is southeast of the Oklahoma City metropolitan area, bordering on Del
City and Midwest City in Oklahoma County.  The Base is bounded by Sooner Road
to the west, Interstate 40 to the north, Douglas Boulevard to the east, and Southeast
74th Street to the  south, as illustrated  on Figure  1-1 (page 1-2).  The property
boundaries of Tinker AFB are shown on Figure 1-2 (page 1-3).  The main portion
of Soldier Creek is to the east of Tinker AFB;  however, two unnamed tributaries
(East and West  Soldier Creeks) originate on the Base.  Soldier Creek flows to the
north from its headwaters near Southeast 59th Street to its confluence with Crutcho
Creek approximately  six miles downstream.  According  to the Federal Facility
Agreement  (FFA) for the Base, the Soldier Creek  Operable Unit  includes Soldier
Creek, its tributaries, and any area underlying or adjacent to the waterway that may
be  contaminated   by  the migration  of hazardous  substances,  pollutants,  or
contaminants  from Tinker AFB.  The primary study area for this operable unit
consisted of the tributaries that directly receive discharges or runoff from Tinker AFB
(West and  East Soldier  Creeks) and the main stem of Soldier  Creek from  its
headwaters downstream to East Reno Avenue, as illustrated on Figure 1-2 (page 1-3).

1.2 Site Demography and Land Use
Approximately 20,000 individuals work at Tinker AFB, of which 8,000 work at the
Building 3001  complex. Tinker AFB accommodates 530 family housing units and 7
dormitories.  Oklahoma County has a population of approximately 629,000.  The
populations of Oklahoma City, Midwest City, and  Del City, which border Tinker
AFB, are approximately 407,000, 58,000, and 33,000, respectively.
Tinker AFB - Soldier Creek
Record of Decision                  1-1

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                                                                   N
                                                  SOLDIER CREEK


                                                          N.E. 23RD  STREET
WILL ROGERS
WORLD AIRPORT
                           1-2
FIGURE 1-1
SITE VICINITY
TINKER flFB-SOLDIER CREEK OPERflBLE UNIT
RECORD OF  DECISION

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          Soldier Creek and its branches are bordered mainly by recreational and residential
          areas with some areas supporting commercial and industrial uses.  The areas east of
          the Base are primarily used for agriculture.   On-base areas of the Soldier Creek
          Sediment and Surface Water Operable Unit are adjacent to the eastern-most runway
          area, the Building 3001 complex, and the Industrial Wastewater Treatment  Plant
          (IWTP).   Off-base portions  of the Soldier Creek Sediment  and Surface Water
          Operable Unit are in the 100-year floodplain, but the floodplain is limited in extent.
          The on-base portions of East and West Soldier Creeks are not  included in the 100-
          year floodplain.

          1.3  Climatology
          The climate at Tinker AFB is typically characterized by long, dry, hot summers. The
          average annual temperature  is approximately  60 to 62  degrees Fahrenheit.   The
          highest average monthly precipitation occurs in May.  Precipitation decreases in June,
          setting the stage for hot, dry summers. June, July, and August are the hottest months
          of the year. Precipitation is also high in autumn, but tapers off with January  being
          a dry month. The average annual precipitation for Tinker AFB is approximately 40
          inches.  The average annual  precipitation for the  entire Oklahoma City area is
          approximately 32 inches.  The prevailing wind direction is from  the south-southeast.

          1.4  Water Resources
          Soldier Creek is classified by the State of Oklahoma as  an unlisted  surface water.
          The State of Oklahoma designates unlisted surface waters as suitable for agriculture,
~~^        industrial  and  municipal  process  and  cooling water,  secondary body-contact
          recreation, limited  fishery, and aesthetics.  Soldier Creek is primarily used  for
          aesthetics and limited recreation.

          The Soldier Creek Sediment and Surface Water Operable Unit  lies within the  limits
          of the Garber-Wellington Groundwater Aquifer  Basin, also known as  the Central
          Oklahoma Aquifer. Regionally, the Garber-Wellington is the single, most important
          source of potable groundwater in the Oklahoma City metropolitan area; however, it
          is not  considered a sole source aquifer. The four aquifer zones present in the area
          of the operable unit from shallowest to deepest are the perched aquifer where
          present, the top of  regional  aquifer zone, the regional aquifer zone, and the
          producing zone. The perched  aquifer is not a source of drinking water. The top of
          regional and regional aquifer zones may be potential sources of drinking water. The
          producing zone is a source of drinking water for the  area. The top of regional, the
          regional, and the producing aquifer zones are part of the Garber-Wellington aquifer.
          A comprehensive  discussion  of the  regional  and  site-specific  geology  and
          hydrogeology is presented in the RI report, which is available in the Administrative
          Record file.
          Tinker AFB - Soldier Creek
          Record of Decision                   1-4

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                                    2.0  SITE HISTORY
          This section of the ROD presents a summary of the site history, including previous
          and current investigations, remedial activities conducted at the operable unit, and
          enforcement activities.

          Tinker AFB is a major industrial complex for overhauling, modifying, and repairing
          military aircraft, aircraft engines, and accessory  items.  Industrial operations at the
          Base began in 1942.

          2.1 Previous Investigations and Remedial Activities
          As part of the overall Air Force Installation Restoration Program, Tinker AFB began
          environmental  investigations  of previously used waste  disposal sites in  1981.  A
          basewide sampling program was conducted  in 1983. Because of  the presence of
          trichloroethene and  chromium in  the groundwater, portions of Tinker AFB were
          added to the National Priorities List (NPL) on July 22, 1987.  The  site was divided
          into three  operable  units, Building 3001, which includes the groundwater  below
          Building 3001, the North Tank Area, Pit Q-51, and Water Wells 18 and 19; Soldier
          Creek sediment and  surface water; and Soldier Creek groundwater.  As previously
          stated, this ROD addresses the Soldier Creek Sediment and Surface  Water Operable
          Unit.

-;.        Numerous  activities have been conducted to identify and eliminate potential sources
          of contamination to  Soldier Creek. In 1986, excavation activities  were conducted
          along  East and  West  Soldier  Creeks.   Approximately 7,500  cubic  yards  of
          contaminated sediment  were removed.   In  addition, more  than  14 underground
          storage tanks and solvent pits  were  excavated and removed or filled and abandoned
          in place in  the vicinity of Soldier Creek over  the last three years.

          In 1989, a  survey to  identify possible old industrial waste cross-connections in the
          Building 3001 area was performed.  Based on this study, in 1990 and 1991, several
          industrial cross-connections that  may have been contaminating the Soldier Creek
          storm-water system with industrial wastes were identified and  eliminated.

          In 1990, a complete overhaul  of the Plating Shop Facility inside Building 3001 was
          initiated. This overhaul included replacing all of  the process equipment and coating
          the basement floor with a material resistant  to chromic acid, which is used in the
          Plating Shop operations. By replacing potentially leaking equipment and preventing
          contaminants from entering the concrete and soil in the area, chromium and other
          contaminants used in the Plating Shop operations may be prevented from reaching
          the groundwater and West Soldier Creek.
         Tinker AFB - Soldier Creek
         Record of Decision                  2-1

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Since Tinker AFB was added to the NPL, a remedial investigation/feasibility study
(RI/FS) of the Soldier Creek Sediment and Surface Water Operable Unit has been
conducted.  Fieldwork was conducted in July 1990 (Phase I) and June 1991 (Phase
II). The results of the RI, the baseline risk assessment, and the FS conducted for the
Soldier Creek Sediment and Surface Water Operable Unit are summarized in
subsequent sections of this ROD. Table 2-1 (page 2-3) presents a brief summary of
previous  activities conducted at Tinker AFB under the Installation Restoration
Program  at or in the vicinity of Soldier Creek.

2.2  Current  Remedial Activities
Remedial activities are currently underway at the Building 3001 Operable Unit at
Tinker AFB.  This operable unit comprises the groundwater  contamination that
underlies Building 3001 itself and West Soldier Creek, the North Tank area, Pit Q-51,
and Water Wells 18 and 19. The Building 3001 ROD was signed on August 16,1990.
The remedy selected for the remediation of the contaminated groundwater includes
extraction and  treatment.   The  groundwater treatment  process  uses  chemical
precipitation  and air stripping to remove inorganic and  organic contaminants,
respectively, from extracted groundwater.  Performance testing is ongoing, and trial
operation has begun. The treated water is to be reused at the Base in its industrial
operations. Remedies also included  removing and disposing of contaminated pit
contents at Q-51, and removing and disposing of contaminated subsurface soil in the
North Tank Area.  Water Wells 18 and 19 were plugged in 1986.

2,3  Enforcement Activities
On December 9, 1988, the U.S. Environmental Protection Agency (EPA) Region 6,
the Oklahoma State Department of Health (OSDH), and the U.S. Department of the
Air  Force,  Tinker AFB  signed  an  FFA (Administrative  Docket  Number
NPL-U3-2-27) under the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980 (CERCLA) Section 120 as amended by  the Superfund
Amendments  and  Reauthorization  Act of  1986  (SARA).   The  intent of this
agreement is to ensure that the  past and present activities at the Tinker AFB NPL
Site are thoroughly investigated and appropriately remediated to protect the public
health, welfare, and environment.  The FFA establishes requirements for  the
performance  of RI/FSs at  the operable units in accordance with CERCLA.   In
addition,  the FFA establishes procedures and schedules for developing, implementing,
monitoring, documenting, and approving response actions at both the Building 3001
and Soldier Creek Sediment and Surface Water Operable Units, in accordance with
CERCLA, the National Oil and Hazardous Substances  Pollution Contingency Plan
(NCP), and Superfund guidance and policy.  The agreement sets procedures for
remedial  actions and specifies that Tinker AFB will establish and maintain an
Tinker AFB - Soldier Creek
Record of Decision                  2-2

-------
                    TABLE2-1
SUMMARY OF PREVIOUS INVESTIGATIONS AND ACTIVITIES
              TINKER AFB - SOLDIER CREEK
                 RECORD OF DECISION
INVESTIGATION/ACnvrrY
Installation Restoration Program Phase II
Confirmation/ Quantification Stage 2
Investigation
Sediment and Surface Water Sampling
Sediment Sampling and Dredging
North Tank Area
Water Wells IS and 19
Surface Water Sampling
Sediment and Surface Water Sampling
NPDES Surface Water Sampling
Building 3001 Remedial Investigation
Quarterly Groundwaicr Sampling
Final Storm Sewer Investigation
For Soldier Creek
Industrial Wastewater Treatment
Plant Remedial Investigation
Soldier Creek Remedial Investigation,
Phase I and II
Pit Q-51
Remedial Design of Bunding 3001
Groundwater Treatment System
Construction of Building 3001
Groundwater Treatment System
INVESTIGATOR
Radian
Corporation
EPA
[iarry Keith
fc Sons, Inc.
Tinker AFB
Tinker AFB
linker AFB
Oklahoma Slate
^cpanmcni of Health
linker AFB
Tulsa COE
TulsaCOE
NUS
Corporation
ruUaCOE
3iV Waste Science
ind Technology Corp.
linker AFB
3£V Waste Science
ind Technology Corp.
3&V Waste Science
nd Technology Corp.
!
DATES
5/84 - 7/S4
10/84, 11/84
110/85
1/86 & 5/86
1%5-Prescm
L986
V37 - 9/87
5/37
VS6 - 7/S7
PURPOSE !
Determine if solvent storage and waste
disposal resulted in environmental
untamination at Tinker AFB.
Evaluate the effects of wastewater
Jiscbarge from Tinker AFB on water
quality of Crutcho and Soldier Creeks.
Evaluate magnitude of contamination in
East and West Soldier Creeks. Dredging of
unknown volume of sediment from on- base
portions of East and West Soldier Creeks.
Remove fuel contamination in the
groundwater north of Building 3001.
Plugged and abandoned contaminated
water wells inside of Building 3001.
Sample I* i h and Sanitary Treatment Plant
surface water discharges.
Sample sediment and surface water from
East Soldier Creek.
Determine surface water concentrations
downstream of IWTP effluent discharge
ocation.
5/S6 - *'87 Determine groundwater contamination in
1/68 - 6789 be area of Building 3001 and the IWTP.
12/S7 - 3R9
VB8. 10/88
10/89
yss - 9/90
July 1990
lane 1991
Sample groundwater in the area of
Building 3001, the IWTP, and East and
West Soldier Creeks.
Sample surface water to identify
contaminant release from Building 3001
storm severs 10 East and West Soldier
Creeks.
Sample groundwater in the vicinity of the
rWTP to assess groundwater contamination
Kneath the rWTP.
Determine the extent of sediment and
surface water contamination along East.
vlain, and West Soldier Creeks.
1991 (Cleaned and abandoned old solvent pit
inside of Buildine 3001.
991 Design of treatment system to remediate
groundwaier contamination associated with
pe Building 3001 Operable Unit that
underlies West Soldier Creek.
952
Construction of treatment system to
cmcdiatc groundwater contamination
issociated with the Building 3001 Operable
Jnit that underlies West Soldier Creek.
Startup of treatment system estimated to be
Q1993.
                      2-3

-------
Administrative Record  that will include all documents that form the basis for the
selection of a response action at both the Building 3001 and Soldier Creek Sediment
and Surface Water Operable Units at the Tinker AFB Site.  An Administrative
Record for the Soldier Creek Groundwater Operable Unit at Tinker AFB will also
be established.
Tinker AFB - Soldier Creek
Record of Decision                   2-4

-------
                           3.0  COMMUNITY PARTICIPATION


         The Administrative Record and the Proposed Plan for the Soldier Creek Operable
         Unit were released to the public for comment in April 1993.  The RI, FS, Risk
         Assessment, Environmental Assessment, and FS Initial Screening of Alternatives
         reports, and the Proposed Plan are contained in the Administrative Record file and
         are available to the public at four locations: the Midwest City Public Library, Tinker
         AFB, the OSDH offices in Oklahoma City, Oklahoma, and the EPA Region 6 offices
         in Dallas, Texas.  The notice of availability of these documents was published in a
         newspaper announcement on April 16, 1993.

         Tinker AFB solicited input from the community on the proposed remedy for this
         operable unit.  A public comment period was held from April 16, 1993, to June 17,
         1993, to encourage public participation in the remedial process.  Both the public
         comment period and the public meeting were initially announced to the public in the
         Daify Oklahoman, a large local newspaper of general circulation on April 16,  1993.
         A fact  sheet was prepared and sent  to individuals on the mailing list on April 23,
         1993.  The public meeting was held in Midwest City on April 27,  1993. At this
         meeting, representatives  of  Tinker AFB presented information and  answered
         questions about the Soldier Creek Sediment and Surface Water Operable Unit and
         the remedial alternatives under consideration.  Representatives of the  EPA and
         OSDH were present at the meeting. Tinker AFB provided notice of the public
-*r       meeting through  a newspaper announcement on  April 26,  1993,  and a press
s?       conference held on April 26,1993.  During this meeting, the public comment period
         was extended for 30 days. A public notice was placed in the community section of
         the Daify Oklahoman for three days notifying the public of this extension.  On May
         17, 1993, the Base newspaper also ran a story detailing cleanup alternatives and the
         extension date. A transcript of the public meeting is available in the Administrative
         Record file.  Responses to the comments received during the public comment period
         are included in the Responsiveness Summary in Appendix A of this ROD.  The
         decision for this  operable unit is  based  on  the  information contained in the
         Administrative Record file.
         Tinker AFB - Soldier Creek
         Record of Decision                  3-1

-------
            4.0 SCOPE AND ROLE OF OPERABLE UNIT
The Tinker AFB NPL Site comprises three operable units:
    •    Building 3001, which includes the groundwater below Building 3001, the
        North Tank Area, Pit Q-51, and Water Wells 18 and 19.
    •    Soldier Creek Sediment and Surface Water.
    •    Soldier Creek Groundwater.

Remedies for the Building 3001  Operable  Unit have  already  been selected.
Contaminated groundwater is the principle threat at this operable unit. The remedy
includes the extraction and treatment of groundwater below Building 3001.  As
discussed in Section 2.2 of this ROD, treatment system trial operations have begun.
The remedies also included removing and disposing of contaminated pit contents
from Pit Q-51, and removing and disposing of fuel products in the subsurface soil at
the North Tank Area. Water Wells 18 and 19 were plugged in September 1986.

This ROD addresses the Soldier Creek Sediment and Surface Water Operable Unit.
The purpose  of this response action is to address the risks to the public and the
environment from direct contact with Soldier Creek sediment and surface water and
the threat of migration of contaminants from the stream to the groundwater below
Soldier  Creek.  The overall objective  is to prevent exposure to and migration of
contaminants with concentrations greater than the final remediation goals. These
goals are based on the baseline risk assessment conducted for the operable unit and
are presented in Section 6.0 of the ROD.

The groundwater associated with Soldier Creek was investigated during the RI for the
Soldier Creek Sediment and Surface Water Operable Unit. However, because of the
complexity  of potential groundwater interactions  between the operable units at
Tinker AFB and because not enough  data have been collected to determine the
nature of the vertical and  horizontal extent  of contamination, the groundwater
associated with Soldier Creek is to be addressed as a separate operable unit under
CERCLA and the FFA,
Tinker AFB - Soldier Creek
Record of Decision                  4-1

-------
                     5.0 SITE CHARACTERISTICS
This section provides a summary of the nature and extent of sediment and surface
water contamination at the Soldier  Creek Sediment and Surface Water Operable
Unit. This summary is based on the data generated by the work performed pursuant
to the RI/FS.  A comprehensive discussion of the operable unit characteristics is
presented in the RI report.

5.1  Sources of Contamination
Several possible past sources of contamination to Soldier Creek from Tinker AFB
have been identified. These  may have been indirect sources of chemicals to Soldier
Creek through  surface water runoff or from possible  perched  aquifer zone
groundwater discharge to the  creek.  These  past sources include Building 3001,
underground storage tanks in the north and southwest tank areas, abandoned solvent
pits, and a storm drain outfall south of the IWTP. However, as discussed in Section
2.1, these  sources have been eliminated through  remedial activities implemented at
the Base.  The approximate locations of these former possible sources are shown on
Figure 1-2 (page 1-3).

A total of 12  industrial outfalls  and storm drains are known to have discharged
directly to East and West Soldier Creeks on the Base. All of the cross-connections
between the outfalls and the industrial waste lines were closed by 1990.  The storm
drains are still active.  All industrial  waste is now transported to the IWTP through
underground lines. Off-base industrial outfalls and storm drains, located downstream
on East and West Soldier Creeks and upstream and downstream along the main
stream, discharge flows into  Soldier  Creek and its tributaries.  These possible past
on-base and  current off-base point  sources could  have discharged hazardous
substances and other contaminants directly into the creeks.

Accidental spills of chemical substances may have  occurred at on-base or off-base
locations within the Soldier Creek drainage system.  Such spills may have resulted in
contaminant transport to  Soldier  Creek by surface  runoff or  to  underlying
groundwater by leaching and percolation from the soil.

Several potential off-base contamination sources may exist, including but not limited
to underground gasoline storage tanks associated with service stations, a salvage yard,
an auto repair shop, a paint shop, a vacant lot north of Tinker AFB that contains
dumped materials, and other industrial service and manufacturing facilities in  the
vicinity of  Soldier Creek.  The paint shop and vacant lot are no longer considered off-
base because Tinker AFB purchased the property that was formerly the site of these
potential sources in 1992.  These potential sources are shown on Figure 1-2 (page
1-3).

Tinker AFB - Soldier Creek
Record of Decision                  5-1

-------
5.2  Location and Extent of Sediment Contamination
The extent of sediment contamination in Soldier Creek was assessed by collecting
hand-augered samples to a depth of 5 feet below the stream bed. Fourteen volatile
organics, 29 semi-volatile organics, and 20  inorganics were detected  in sediment
samples collected from Soldier Creek and its tributaries.  The sample locations for
both phases of the  RI are shown on  Figure 5-1 (page  5-3).

Table 5-1 (pages 5-4 and 5-5) presents the volatile organics, semi-volatile organics,
and inorganics detected in Soldier Creek sediment during each phase of the RI. The
table also presents the frequency of detection, the concentration range detected, and
the background  concentrations.   Background sediment sampling locations were
selected so as not to be influenced by potential sources of contamination; therefore,
the background sample locations were sited on private property along east tributaries
of Soldier Creek. The following subsections summarize the extent of contamination
in the sediment.

5.2.7  Volatile Organic  Contamination
Methylene  chloride,  acetone, chloroform, tetrachloroethene, toluene,  and  xylene
(total)  were  the  most  frequently  detected   compounds.     Chloroethane,
1,2-dichloroethene, ethylbenzene, and trichlorothene were detected at only on-base
sample locations. Vinyl acetate and benzene were detected at only off-base sample
locations. Compared to  all volatile organics detected during Phase I of the RI, the
contaminants detected at the highest concentrations during Phase I of the RI were
methylene  chloride and 1,2-dichloroethene.  Compared to all volatile organics
detected during  Phase II  of the RI, the contaminants detected at the  highest
concentrations during Phase II  of the RI were methylene  chloride and acetone.
Acetone, chloroform, methylene chloride, tetrachloroethene, toluene,  and  xylene
(total) were detected at background sample locations.  Several compounds detected
during Phase I of the RI [1,2-dichloroethene (total), trichloroethene, Chloroethane,
ethylbenzene, and  vinyl  acetate]  were  not  detected  during Phase II  of the  RI.
Benzene was only detected during Phase II of the RI. In general, there appeared to
be higher  volatile  organic concentrations on-base and at depths greater  than 6
inches.  Building 3001 outfalls have been identified as past sources of chloroform,
Chloroethane,  1,1,1-trichloroethane,  trichloroethene,  tetrachloroethene, benzene,
toluene, and xylene (total) contamination.  Building 3001 is no longer a source of
contamination to  Soldier  Creek because the industrial cross-connections were
removed.  While the off-base  locations where contaminants were  detected  are
downstream of the Building 3001 outfalls, these locations range from one half to one
mile downstream of the Building 3001 outfalls and  receive surface runoff from
numerous off-base potential sources of contamination.  The overall concentration of
volatile organics detected in the sediment was higher in Phase I than Phase II of the
RI. The lower concentrations detected during Phase II of the RI may be the result
of natural attenuation, degradation, or migration of the contaminants.

Tinker AFB - Soldier Creek
Record of Decision                  5-2

-------
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-------
                   TABLE 5-1
CONTAMINANTS DETECTED IN SOLDIER CREEK SEDIMENT
             TINKER AFB - SOLDIER CREEK
                RECORD OF DECISION
CHEMICAL
Acetone
Benzene
Carbon Disulfide
Chlorobenzene
Chloroe thane
Chloroform
1,2-Dichloroethene (Total)
Ethylbenzene
Methylene Chloride
Tetrachloroethene
Toluene
Trichloroethene
Vinyl Acetate
Xylene (Total)
Acenaphthene
Anthracene
BenzoCA)anthracene
BenzoCB)fluoranthene
BenzofKWuorantbene
Benzo(G,H,I)perylene
Benzo(A)pyrene
Bis(2-ethylhocyl)phthalate
Butylbenzylphthalate
2 - Chloronaphthalene
Chrysene
Dibenz(A^i)anthracene
Dibenzofuran
1,2-Dichlorobeiuene
13-DichIoroben2ene
FREQUENCY OF
RI PHASE DETECTION (1)
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase I
Phase I
Phase I
Phase!
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
32/41
:3/n
0/41
1/17
1/41
2/17
4/41
1/17
1/41
0/17
41/41
5/17
2/41
0/37
1/41
0/17
41/41
12/17
2/41
5/17
12/41
4/17
1/41
0/17
1/41
0/17
3/41
7/17
12/41
17/41
19/41
17/41
14/41
11/41
18/41
41/41
5/41
4/41
20/41
2/41
7/41
4/41
4/41
RANGE OF SAMPLE
QUANTITATION
LIMITS (2)
fug/tetfJ)
2.0 to 10.0
10.0 to 12.0
ND
1.0 to 6.0
6.0 to 10.0
0.9 to 6.0
6.0tolO.O
6.0
12.0
ND
1.0 to 10.0
0.6to6.0
6.0 to 10.0
ND
3.0 to 10.0
ND
1.0 to 10.0
1.0 to 6.0
1.0 to 10.0
2.0 to 6.0
1.0 to 10.0
0.9 to 6.0
6.0 to 10.0
ND
0.9 to 10.0
ND
4.0tolO.O
0.7to6.0
17.0 to 3,300.0
10.0 to 3300.0
38.0 to 3,300.0
39.0 to 3300.0
41.0 to 3300.0
120.0103300.0
27.0to3300.0
60.0 to 3300.0
29.0 to 3300.0
220.0 to 3300.0
63.0 to 3300.0
48.0to3300.0
35.0 to 3300.0
30.0 to 3300.0
31.0 to 3300.0
RANGE
OF DETECTED
CONCENTRATIONS
(us/kg)f3)
ND to 1,700.0
ND to 51.0
ND
ND to 1.0
ND to 36.0
ND102.0
ND to 78,000.0
ND to 10.0
ND to 86.0
ND
ND to 9,200.0
NDto2.0
ND to 180,000.0
ND
ND104.0
ND
ND to 140,000.0
ND to 51.0
ND to 83,000.0
NDtoIl.O
ND to 980.0
NDto6.0
ND to 4,100.0
ND
NDloO.9
ND
ND to 1,000.0
NDto6.0
ND to 1,100.0
ND to 1,500.0
ND to 4,800.0
ND to 9,200.0
ND to 5300.0
ND to 4,100.0
ND to 4,400.0
ND to 46,000.0
ND to 720.0
ND to 1,600.0
ND to 7,100.0
ND to 110.0
ND to 480.0
ND to 3,100.0
ND to 280.0
BACKGROUND
LEVELS
(ug/kg)f3)
NDW9.0
ND to 51.0
ND
ND
ND
ND
ND
ND
ND
ND
5.0
NDto2.0
ND
ND
ND
ND
9.0 to 10.0
ND to 30.0
ND
ND to 11.0
ND
NDto6.0
ND
ND
ND
ND
ND
NDio6.0
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
                      5-4

-------
                                         TABLE 5-1 (Continued)
CONTAMINANTS DETECTED IN SOLDIER CREEK SEDIMENT
TINKER AFB - SOLDIER CREEK
RECORD OF DECISION
CHEMICAL
1,4-Dichlorobenzene
33— Dichlorobcnzidine
2,4— Dimethylphenol
Di-n-butylphthalate
Di-n— octylphthalate
Fluoranthene
Fluorene
Indeno(l,23-CD)pyrene
2-Melhylnaphlhalene
2-Meihylphenol
4-Methylphenol
Naphthalene
Phenanthrene
Pyrene
Aluminum
Arsenic
Barium
Cadmium
Calcium
Chromium
Cobalt
Copper
Cyanide
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Vanadium
Zinc
FREQUENCY OF
RI PHASE DETECTION fl)
Phase I
Phase I
Phase I
Phase 1
Phase I
Phase I
Phase I
Phase I
Phase!
Phase!
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase!
Phase I
Phase II
Phase I
Phase I
Phase 11
Phase!
Phase!
Phase!
Phase II
Phase!
Phase!
Phase II
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase!
Phase 1
5/41
1/41
1/41
20/41
16/41
24/41
9/41
11/41
10/41
1/41
1/41
11/41
20/41
21/41
41/41
39/41
41/41
31/41
15/17
41/41
41/41
17/17
41/41
40/41
2/41
0/17
41/41
41/41
17/17
41/41
41/41
13/41
41/41
41/41
14/41
27/41
41/41
41/41
RANGE OF SAMPLE
QUANTITATION
LIMITS (2)
(ug/kgXS)
52.0 to 3300.0
1,600.00 to 3300.0
160.0to3300.0
11.0 to 3300.0
14.0 to 3300.0
3.0to3300.0
57.0 to 3300.0
109K) to 3300.0
14.0 to 3300.0
68.0 to 3300.0
98.0 to 3300.0
44.0 to 3300.0
9.0 to 3300.0
18.0 to 3300.0
423.0(020,000.0
0.97 to 1,000.0
3.21020,000.0
0.55 to 500.0
0.9 to 500.0
348.0 to 500,000.0
2.40 to 1,000.0
4.6 to 1,000.0
1.8 to 5,000.0
4.8 to 2,500.0
230 to 1,000.0
230
827.0 to 10,000.0
22 to 300.0
4.0 to 300.0
83.610500,000.0
42 to 1,500.0
0.12tolOO.O
2.8 to 4,000.0
99.310500,000.0
0.56 to 500.0
0.49 to 1,000.0
1.4 to 5,000.0
3 JO to 2,000.0
RANGE
OF DETECTED
CONCENTRATIONS
(ug/kgY3)
ND to 4,400.0
ND to 1,700.0
ND to 160.0
ND to 2,200.0
ND to 540.0
ND to 11,000.0
ND to 880.0
ND to 3,800.0
ND to 1,900.0
ND to 68.0
ND to 98.0
ND to 690.0
ND to 6,700.0
ND to 10,000.0
423.0 to 42,300.0
ND to 15.7
63.0102,910.0
ND to 428.0
ND to 15.7
653.0to72,500.0
4.9 to 2,020.0
ND to 186.0
ND to 52.1
ND to 600.0
ND to 6.5
ND
827.0 to 41,200.0
2.2 to 586.0
ND to 152.0
179.0 to 20,400.0
8.8 to 1,490.0
NDto2.6
2.8to2270.0
ND to 2300.0
ND to 10.2
ND to 112.0
1.4to52.9
3.5 to 640.0
i'1""
BACKGROUND
LEVELS
(ug/kgK3)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
4,050.0104,060.0
1.6
64.410762
ND
ND to 2.08 j^,,
775.0 to 4,070.^^
8.0108.4 ^""^
NDto9.6
2.5to3.1
14.8 to 36.6
ND
ND
5,780.0 to 10,700.0
6.7 to 7.7
ND to 54.3
734.0 to 1,160.0
56.4 to 100.0
ND
8.0 to 8.6
495.0 to 552.0
ND
0.53 to 0.91
8.8 to 9.4
10.2 to 13.9
Legend:
ND-Not Detected
Note:
(1) Number of samples in which the chemical was positively detected over the number of samples available.
(2) The maximum limit is the contract required quantitalion limit.
(3) The units of concentration for inorganic constituents are mg/kg.

                                                     5-5

-------
5.2.2 Semi-Volatile Organic Contamination
Di-n-butylphthalate,  fluoranthene, bis-(2-ethylhexyl)phthalate, and di-n-octyl-phthalate
were the most frequently detected semi-volatile organic compounds.  Most of the
semi-volatile contaminants detected were found on-base, immediately off-base, or in
stream segments upstream of the  Base.  However, the  maximum  concentrations
detected were all on-base and downstream of Outfall G, which is known to have
discharged semi-volatile organics to East Soldier Creek in the past.  The source of
this contamination in Outfall G was probably Building 3001; however,  this source was
eliminated when the industrial  cross-connections were removed.   The maximum
concentrations were detected primarily in the 0 to 6-inch sampling interval.  The
location of Outfall G is shown on Figure 1-2 (page 1-3).  Samples for semi-volatile
analysis were primarily collected  during Phase I of the RI. Only one sample for semi-
volatile analysis was collected during Phase II of the RI. However, no semi-volatile
organics were detected in the sample. Three samples were collected along Outfall
G in September 1992.   One type  of polychlorinated biphenyl  (PCB-1254) was
detected at all three  sampling  locations.   No  other PCBs were detected.   The
concentrations of the PCB detected were 9.3 parts per million (ppm) at the upstream
sampling location, 1.9 ppm at the middle location, and 0.5 ppm at the  downstream
sample location. PCBs were not analyzed for during the RI because historical data
indicated that PCBs were not present along on-base portions of East Soldier Creek
at significant concentrations (less than one part per billion).  It is possible that the
source of the PCB contamination is from the Outfall G discharge. Although there
are no known industrial processes within Building 3001 that use PCBs, old electrical
transformers were known to have oil that contained PCBs.  All transformers with
PCB-containing oil were replaced in 1989; however, it is possible that before this time
a minor spill of transformer oil containing PCBs could have occurred and entered the
storm drain system.

5.2.3 Inorganic Contamination
Many inorganics were detected at on-base and off-base sample locations; however,
the maximum concentrations detected were generally found on-base.  The maximum
concentrations were detected primarily in the shallow sediment sampling intervals (0
to 2 feet). Cadmium and chromium were detected above background  concentrations
at on-base and off-base locations within East, Main, and West  Soldier  Creeks. All
of the inorganics shown in Table  5-1 (pages 5-4 and 5-5) were analyzed during Phase
I of the RI, however, cadmium, chromium, cyanide, and lead were the only inorganic
analytes analyzed during Phase II of the RI based on the results of a preliminary risk
assessment performed after completion of Phase I of the  RI.  Sources  of inorganic
contaminants in Soldier Creek  may  include Building 3001 and off-base sources.
These  potential  off-base  sources  include  underground gasoline  storage tanks
containing  leaded fuel, salvage  yards, paint shops using leaded paint, and other
facilities associated with auto repair and metal plating. Many of the inorganics may
also be naturally occurring analytes  in the sediment.  Table 5-2 (page 5-7) presents
Tinker AFB - Soldier Creek
Record of Decision                   5.5

-------
                                     TABLE 5-2
                   TYPICAL BACKGROUND SOIL CONCENTRATIONS
                             TINKER AFB-SOLDIER CREEK
                                  RECORD OF DECISION
Constituent
Aluminum
Arsenic
Barium
Cadmium
Calcium
Chromium
Cobalt
Copper
Cyanide
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Vanadium
Zinc
Native U.S. Surface
Soil Concentration
(ppm)m
50,000
6.5
500
MA
3,500-7,900
1.0-70
7
15
NA
1.5
<10-15
5,000-7,000
200-300
0.032
10-20
1.6
0.3
NA
70
<5.0-17
Oklahoma Surface
Soil Concentration
(ppm)(2)
10,000-300,000
1.0-40
100-3,500
0.01-7.0
100,000-400,000
5.0-3,000
1.0-40
2.0-100
NA
7,000-550,000
2.0-200
600-6,000
100-4,000
0.01-0.08
5.0-1,000
400-30,000
0.1-2.0
0.1-5.0
20-500
10-300
Soldier Creek
Background
Concentration (ppm)
4,050-4,060
1.6
64.4-76.2
ND-2.08
775-4,070
8.0-9.6
2.5-3.1
14.8-36.6
ND
5,780-10,700
6.7-54.3
734-1,160
56.4-100
ND
8.0-8.6
495-552
ND
0.53-0.91
8.8-9.4
10.2-13.9
Legend:
NA-Not Available
ND-Not Detected
Notes:
(1) Shacklette, Hansford T., and Josephine G. Boerngen, "Element Concentrations in Soils and
Other Surficial Materials of the Conterminous United States," U.S. Geological Survey
Professional Paper 1270, 1984.

(2) Dragun, James, Ph.D, The Soil Chemistry of Hazardous Materials," Hazardous
Materials Control Research Institute, Silver Spring, Maryland, 1988.
                                        5-7

-------
typical background soil concentrations for inorganic  analytes detected  in Soldier
Creek sediment.  The table shows that the analytes occur in surface materials.  In
general, the metals were detected in samples from the same stream segments during
both phases of the RI.  A more complete analysis of the chemical results can be
found in the RI report.

5.3 Location and  Extent of Surface Water Contamination
The extent of surface  water  contamination  was determined  during  the  RI by
collecting samples at the same locations as the sediment samples.  Fifteen volatile
organics, 5 semi-volatile organics, and 21 inorganics were detected in surface  water
samples collected from Soldier Creek and its tributaries.

Table 5-3 (pages 5-9 and 5-10) presents the volatile organics, semi-volatile organics,
and inorganics detected in  Soldier Creek surface water during each phase of the RI.
The table also presents the frequency of detection, the concentration range detected,
and the background concentrations. The following subsections summarize the extent
of contamination in the surface water.

5.3.1 Volatile  Organic Contamination
Methylene chloride, acetone, chloroform, and 1,1,1-trichloroethane were the most
frequently detected volatile organic compounds.  1,2-Dichloroethene was  only
detected at on-base sample locations.  Benzene, chlorobenzene, and xylene (total)
were  only  detected  at  off-base sample locations.    Bromodichloromethane,
chlorobenzene, chloroform, and methylene chloride were detected at background
sample locations in addition to other upstream locations.  During both phases of the
RI, methylene  chloride was the compound detected at  the highest concentration.
Several compounds were detected only during  Phase II  of  the RI  [benzene,
chlorobenzene,   trichloroethene,   carbon   disulfide,    and   xylene   (total)].
Dibromochloromethane was detected only during Phase I of the RI. There is no
evidence  indicating Tinker AFB has  used chlorobenzene, carbon disulfide, or
dibromochloromethane.   Higher volatile  organic concentrations  were  detected
on-base along  East Soldier Creek and downstream  of outfalls that have  been
documented to  have discharged volatiles into Soldier Creek in the past. The general
trend for West Soldier Creek appears to be relatively higher volatile organic
concentrations on-base than off-base. Building 3001 was eliminated as a source of
contamination to Soldier Creek when the industrial cross-connections were removed.

5.3.2 Semi-Volatile Organic Contamination
Benzo(G,H,I)perylene, benzoic acid,  chrysene, fluoranthene,  and pyrene  were
detected at low concentrations at on-base sample locations, except for benzoic acid
which was only detected off-base.  No general trends or sources of contamination for
surface water semi-volatile organic analytical results could be established.
Tinker AFB - Soldier Creek
Record of Decision                  5-8

-------
                      TABLE 5-3
CONTAMINANTS DETECTED IN SOLDIER CREEK SURFACE WATER
               TINKER AFB - SOLDIER CREEK
                   RECORD OF DECISION
CHEMICAL
Acetone
Benzene
Bromodichloromethane
Bromoform
Carbon Disulfide
Chlorobenzene
Chloroform
Dibromocholorome thane
1 2 - Dichloroethene(Touil)
Methylene Chloride
Tetrachloroethene
Toluene
1,1,1 -TrichJoroetbane
Trichloroethenc
Xylene (Total)
BenzofG,H,I)peryIene
BcnzoicAcid
Chrysene
Fluoranthene
Pyrene
Aluminum
Arsenic
Barium
Beryllium
Cadmium
FREQUENCY OF
RI PHASE DETECTION (1)
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase II
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase I
Phase II
1/35
6/17
0/35
2/17
3/35
1/17
1/35
2/17
0/35
4/17
0/35
2/17
15/35
1/17
3/35
0/17
1/35
1/17
12/35
12/17
3/35
2/17
1/35
4A7
1/35
5/17
0/35
2/17
0/35
1/17
1/35
2/35
1/35
1/35
1/35
31/35
7/35
31/35
1/35
2/35
1/17
RANGE OF SAMPLE
QUANTITATION
LIMITS (2)
fug/LyS)
5.0 to 10.0
4.0 to 32.0
5.0
1.0 to 5.0
3.0 to 5.0
0.9 to 5.0
4.0 to 5.0
5.0
5.0
0,7 to 5.0
5.0
1.0 to 5.0
0.70 to 5.0
5.0
4.0 to 5.0
5.0
5.0
5.0
2.0 to 5.0
0.8 to 5.0
3.0 to 5.0
1.0 to 5.0
1.0 to 5.0
4.0 to 5.0
2.0 to 5.0
1.0 to 5.0
5.0
2.0 to 5.0
5.0
2.0 to 5.0
6.0 to 10.0
0.40 to 10.0
5.0 to 10.0
1.0 to 10.0
1.0 to 10.0
56.9 to 200.0
4.0 to 10.0
2.0 to 200.0
1.0 lo 5.0
3.0 to 5.0
0.94 to 5.0
RANGE
OF DETECTED
CONCENTRATIONS
(uf/LY3)
NDtoS.O
ND to 60.0
ND
NDto2.0
NDlo6.0
ND to 0.9
NDlo4.0
ND to 15.0
ND
ND to 1.0
ND
NDto2.0
NDto6.0
ND to 9.0
NDloS.0
ND
NDtoS.O
ND to 14.0
ND to 14.0
ND to 620.0
NDtoS.O
ND:o6.0
NDtol.0
NDtoS.O
NDto2.0
NDtoS.O
ND
NDto2.0
ND
NDto2.0
NDto6.0
NDtoO.4
NDtoS.O
NDtol.0
ND to 1.0
56.9to7,430.0
NDto9.8
8.1 to 1,900.0
ND to 1.0
ND TO 56.9
ND to 9.4
BACKGROUND
LEVELS
(ug/LV3)
ND
ND
ND
ND
ND
NDtoO.9
ND
ND
ND
ND
ND
ND to 1.0
ND
ND to 9.0
ND
ND
ND ^
ND |r-;
ND \^
NDtoO.8
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
907.0
ND
350.0
ND
ND
ND
                        5-9

-------
                                      TABLE 5-3 (Continued)
CONTAMINANTS DETECTED IN SOLDIER CREEK SURFACE WATER
TINKER AFB - SOLDIER CREEK
RECORD OF DECISION
CHEMICAL
Calcium
Chromium
Cobalt
Copper
Cyanide
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Selenium
Silver
Sodium
Vanadium
Zinc
RI PHASE
Phase!
Phasel
Phase II
Phase!
Phasel
Phasel
Phase II
Phasel
Phasel
Phase II
Phasel
Phasel
Phasel
Phasel
Phasel
Phasel
Phasel
Phasel
Phase!
FREQUENCY OF
DETECTION (I)
31/35
29/35
10/17
11/35
27/35
2/35
1/17
31/35
29/35
13/17
31/35
31/35
17/35
31/35
19/35
2/35
31/35
20/35
31/35
RANGE OF SAMPLE
QUANTITATION
LIMITS (2)
(ug/LV3)
50.8 to 5,000.0
2.0 to 10.0
7.0 to 10.0
3.0 to 50.0
16.01025.0
10.0
22 to 10.0
66.9 to 100.0
1.0 to 3.0
2.0 to 3.0
20.0 to 5,000.0
1.0 to 15.0
9.0 to 40.0
345.0 to 5,000.0
22 to 5.0
2.0tolO.O
504.00 to 5,000.0
2.0 to 50.0
4.5 to 50.0
RANGE
OF DETECTED
CONCENTRATIONS
(UK/LY3)
31,200.0 to 11 7,000.0
ND to 628.0
ND to 36.9
ND to 324.0
ND to 985.0
ND to 18.0
ND to 10.1
66.9 to 4,550.0
ND to 325.0
ND to 34.5
16,400.0 to 40300.0
11.7 to 3,060.0
ND to 3^60.0
921.0to6,680.0
ND to 20.9
ND to 13.1
15,100.0 to 130,000.0
ND to 67.0
4.5 to 2,400.0
BACKGROUND
LEVELS
(ue/LVS)
» 64,300.0
3.8
ND
4.9
ND
ND
ND
1,730.0
3.9
1.4 to 6.0
21,600.0
1,000.0
ND
921.0
ND
ND
21,400.0
2.6
24.5
Legend:
ND - Not Detected.
Note:
(1) Number of samples in which the chemical was positively detected over the number of samples available.
(2) The maximum limit is the contract required quantitation limit.
(3) The units of concentration for inorganic constituents are mg/L.
                                                 5-10

-------
5.3.3  Inorganic Contamination
Many inorganics were detected; however, the maximum concentrations were generally
found on-base. All of the inorganics shown in Table 5-3 (pages 5-9 and 5-10) were
analyzed during Phase I of the RI; however, cadmium, chromium, cyanide, and lead
were the only inorganics analyzed during Phase II of the RI based on a preliminary
risk assessment performed after Phase I of the RI was completed. Cyanide was only
detected at off-base locations W07 and M13 during Phase I and off-base location
M09 during Phase II of the RI.  Cadmium was detected  only  at on-base sample
locations during Phase I of the RI. Cadmium was detected only  at off-base sample
locations during Phase  II of the RI.  Chromium and lead were detected at both
off-base and on-base locations; however, the maximum concentrations were detected
on-base.  Chromium and lead were also detected at background sample locations.
Building 3001 and, potentially, the off-base sources mentioned in Section 5.2.3 are the
origin of inorganics in Soldier Creek. Many of the inorganics  may also naturally
occur in the sediment and surface water.

5.4  Contaminant Characteristics
Acetone, chloroform, methylene chloride, tetrachloroethene, toluene, xylene (total),
cadmium, chromium, and lead are the primary sediment contaminants of potential
concern based on the frequency of detection and maximum  concentrations detected.
Acetone,  chloroform,  methylene  chloride,  tetrachloroethene,  toluene,  1,1,1-
trichloroethene, cadmium,  chromium, and  lead are  the  primary surface  water
contaminants of potential concern. Table 5-4 (page 5-12) summarizes the mobility
of the primary contaminants of concern and states whether the contaminant poses a
carcinogenic or noncarcinogenic health risk to exposed populations.

5.5  Potential Routes  of Migration
The potential routes of migration at the Soldier Creek Sediment and Surface Water
Operable  Unit include infiltration  and direct migration through  surface and
subsurface soil, sediment, and bedrock; groundwater transport; erosion and runoff;
and interactions between site  aquifers and Soldier Creek.
Tinker AFB - Soldier Creek
Record of Decision                  5-H

-------
                          TABLE5-4
    CHARACTERISTICS OF SELECTED CONTAMINANTS OF CONCERN
                    TINKER AFB - SOLDIER CREEK
                       RECORD OF DECISION
CHEMICAL
OF CONCERN
Acetone
Chloroform
Methylene Chloride
Tetrachloroethene
Toluene
1,1,1 -Trichloroethene
Xylene (total)
Cadmium
Chromium
Lead
MEDIA OF
CONCERN
Sediment
Surface Water
Sediment
Surface Water
Sediment
Surface Water
Sediment
Surface Water
Sediment
Surface Water
Sediment
Surface Water
Sediment
Sediment
Surface Water
Sediment
Surface Water
Sediment
Surface Water
MOBILITY
Very Mobile
Very Mobile
Extremely Mobile
Very Mobile
Very Mobile
Very Mobile
Very Mobile
N/A
N/A
N/A
TYPE OF
HEALTH RISK
Noncarcinogenic
Probable Carcinogenic
Carcinogenic
Carcinogenic
Noncarcinogenic
Noncarcinogenic
Noncarcinogenic
Noncarcinogenic
Noncarcinogenic
Noncarcinogenic
Legend:
N/A - Not Applicable
                             5-12

-------
                    6.0 SUMMARY OF SITE RISKS

This section summarizes the findings of the baseline risk assessment conducted for
the Soldier Creek Sediment and Surface Water Operable Unit.  The complete risk
assessment is presented in  the Risk Assessment report, which is included in  the
Administrative Record file.

6.1   Overview of Baseline Risk Assessment
A baseline risk assessment was conducted as required under CERCLA to evaluate
potential impacts to human health and the environment posed by site contaminants
absent a remedial action (i.e., if the operable unit was not cleaned up). Both current
and future land use scenarios were evaluated. The risk assessment consisted of the
identification of chemicals of potential  concern,  an  exposure assessment, a toxicity
assessment, a risk characterization, and an environmental assessment.

6.2   Contaminants of Potential  Concern
Contaminants of potential concern (COCs) are contaminants that have been detected
at the Soldier Creek Sediment and Surface Water Operable Unit.  Sixty-three
sediment and 41 surface water chemicals were identified as COCs for this Soldier
Creek operable  unit.  Toxicity information for all of the  COCs was evaluated
including, where applicable, slope factors and criteria for noncarcinogenic effects.
The COCs detected within the media of concern are listed in Tables 5-1 (pages 5-4
and 5-5) and 5-2 (pages 5-8 and 5-9).  Twenty-two of these compounds are potential
or probable human carcinogens.

For determining risk assessment concentrations, either central tendency or reasonable
maximum exposure (RME) calculations are used.  Central  tendency assumes an
average or mean value for the concentrations used in the risk assessment. The RME
value is based on the highest exposure that is expected to occur at a site.  Risk
assessments that use RME values are more  conservative than those using central
tendency values.  The risk assessment for the Soldier Creek Sediment and Surface
Water Operable Unit used RME values.

Because of the uncertainty associated with any estimate of exposure concentrations,
the 95 percent upper one-sided confidence limit on the arithmetic mean was used as
the concentration of the COCs in the risk assessment. This means that, 95 percent
of the time, the real mean will not exceed the number that has been chosen as the
concentration. For contaminant concentrations reported as "Not Detected" ("ND")
in the RI, one half the detection limit was used as the risk assessment concentration.
Tinker AFB - Soldier Creek
Record of Decision

-------
6.3  Toxicity Assessment
The  toxicity assessment characterized available human health and environmental
criteria for the COCs and qualitatively related potential chemical exposures (dose)
to expected adverse health effects (response).  Included in this assessment are the
pertinent standards, criteria, advisories, and guidelines developed for the protection
of human health and the environment. An explanation of how these values were
derived and how they apply is presented below.

Slope factors have been developed by EPA's Carcinogenic Assessment Group for
estimating  excess  lifetime cancer  risks associated with exposure to potentially
carcinogenic chemicals. Slope factors, 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 upperbound estimate of the excess  lifetime cancer risk associated with
exposure at that  intake level.  The term "upperbound" reflects the conservative
estimate of the risks calculated from the slope factor.  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.
Slope factors for the COCs at the operable unit are presented in Table 6-1 (pages
6-3 and 6-4).  The sources of the slope factors are primarily EPA publications and
data bases. Specific references are given in Table 6-1 (pages 6-3 and 6-4).

Reference doses (RfDs) have been developed by EPA for indicating the potential for
adverse effects from exposure to chemicals exhibiting noncarcinogenic effects. RfDs,
which are expressed in  units  of mg/kg-day, are estimates of lifetime daily exposure
levels for humans, including  sensitive individuals, that are likely to be without an
appreciable risk of adverse health effects.  Estimated intakes of chemicals from
environmental media (e.g., the amount of a chemical ingested from contaminated
water) can be  compared  with  the RfD.   RfDs   are  derived  from  human
epidemiological 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).

These uncertainty factors help  ensure that  the RfDs will  not underestimate the
potential for adverse noncarcinogenic effects to  occur.  RfDs for the COCs are also
presented in Table 6-1  (pages 6-3 and 6-4). The sources of the RfDs are primarily
EPA publications  and  data bases.   Specific references are given  in Table 6-1
(pages 6-3 and 6-4).

6.4  Exposure Assessment
The exposure assessment identified potential pathways and routes for COCs to reach
receptors and the estimated  contaminant concentration at the points of exposure.
A receptor is a human  population or any living organism other than a human that
may  be exposed to contaminants in site media. Exposure pathways by which humans

Tinker AFB - Soldier Creek
Record of Decision                  6-2

-------
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could be exposed to COCs were identified based on reasonable assumptions about
current and  future uses of the operable unit.  Risks  associated with incidental
ingestion and dermal contact with sediment and surface water were  evaluated for
both adult workers and recreational users (child combined with adult) because these
exposure pathways represent both current and future land uses.  The adult workers
are considered  potentially exposed on-base populations,  and the recreational users
are considered  potentially exposed off-base populations.

For each potentially significant  exposure pathway at  Soldier Creek,  exposure
assumptions  were made for RMEs.  A RME represents a situation that is more
conservative  than an average case but is not a worst-case scenario.  The  RME
scenario is developed to reflect the types and extent of exposures  that could occur
based on the likely  or expected use of the operable unit in the  future.  Ten  RME
scenarios were examined for the on-base and off-base Soldier Creek stream segments,
for both current and future risks:

Off-Base Residents-Current Land Use
    •   Incidental ingestion and dermal contact with contaminants in surface water
        while swimming.
    •   Incidental ingestion and dermal contact with contaminants in surface  water
        while wading.
    •   Incidental ingestion  and  dermal contact  with  contaminants  in surface
        sediment (0 to 6 inches) while swimming or wading.

On-Base Workers-Current Land Use
    •   Incidental ingestion and dermal contact with contaminants in surface water
        while performing construction or repair.
    •   Incidental ingestion  and  dermal contact  with  contaminants  in surface
        sediment (0 to 6 inches) while performing construction or  repair.

Off-Base Residents-Future Land Use
    •   Incidental ingestion and dermal contact with contaminants in surface water
        while wading.
    •   Incidental ingestion and dermal contact with contaminants in surface water
        while swimming.
    •   Incidental ingestion  and   dermal contact  with  contaminants  in deeper
        sediment (0 to 5 feet) while swimming or wading.

On-Base Workers-Future Land Use
    •   Incidental ingestion and dermal contact with contaminants  in surface water
        while performing construction or repair.
    •    Incidental ingestion  and   dermal contact  with  contaminants  in deeper
        sediment (0 to 5 feet) while performing construction or repair.

Tinker AFB - Soldier Creek
Record of Decision                    6-5

-------
Sediment, surface water, and groundwater exposure pathways were considered during
the risk assessment process. However, only the sediment and surface water exposure
pathways are addressed in this discussion because the horizontal and vertical extent
of groundwater  contamination is not known and because  of the complexity of
potential groundwater interactions between the operable units at Tinker AFB. The
groundwater associated with Soldier Creek will be addressed as a separate operable
unit in accordance with the FFA and CERCLA.

The exposure frequency and duration assumptions, as well as the other assumed
factors used to calculate the intake and dose absorbed values used in turn to develop
the human health risks, depend on the exposure population, exposure pathway, and
type of contaminant. The equations used to calculate intakes and absorbed doses for
each COC at the Soldier Creek Sediment and Surface Water Operable Unit are as
follows:

Residential Exposure: Ingestion of Chemicals in Surface Water While Swimming or
Wadin  CCurrent and Future Exosures')
                        HIF =           x
                                 BW x AT x 365
                    Intake  (mg/kg-day)  = HIF x CW
where,
    CW = Chemical Concentration in Water (mg/L)
    HIF = Human Intake Factor (L/kg-day)
    CR = Contact Rate (liters/hour)
    ET = Exposure Time (hours/event)
    EF = Exposure Frequency (events/year)
    ED = Exposure Duration (years)
    BW = Body Weight (kg)
    AT = Averaging Time (period over which exposure is averaged in years)
Tinker AFB - Soldier Creek
Record of Decision                  6-6

-------
 Construction Worker Exposure:  Ingestion of Chemicals in Surface Water ^Current
 and Future Exposures')

                                          X ED
                                    x AT X 365
                    Intake  (mg/kg-day) = HIF x CW
where,
    CW = Chemical Concentration in Water (mg/L)
    HIF = Human Intake Factor (L/kg-day)
    IR = Ingestion Rate (L/day)
    ED = Exposure Duration (years)
    EF = Exposure Frequency (events/year)
    BW = Body Weight (kg)
    AT = Averaging Time (years)

Residential Exposure:   Ingestion of Chemicals in Sediment While Swimming and
Wading (Current and Future Exposures!

                     HIF  = IR x CF x FI x EF x ED
                                 BW x AT x 365
                    Intake (mg/kg-day)  = HIF x CS
where,
    HIF = Human Intake Factor (L/kg-day)
    CS = Chemical Concentration in Soil (mg/kg)
    IR = Ingestion Rate (mg soil/day)
    CF = Conversion Factor (10"6 kg/mg)
    FI = Fraction Ingested from Contaminated Source (unitless)
    EF = Exposure Frequency (days/year)
    ED = Exposure Duration (years)
    BW = Body Weight (kg)
    AT = Averaging Time (years)
Tinker AFB - Soldier Creek
Record of Decision                  6-7

-------
Residential Exposure:   Dermal Contact of Chemicals in Surface Water While
Swimming or Wadin  Current and Future Exosures')
                  HTF ~         "      X EF X ED X CF
                                 BW x AT X 365
               Absorbed Dose (mg/kg-day)  = HIF x CW
where,
    HIF = Human Intake Factor (L/kg-day)
    CW = Chemical Concentration in Water (mg/L)
    SA = Skin Surface Area Available for Contact (cm2)
    PC = Chemical-specific Dermal Permeability Constant (cm/hr)
    ET = Exposure Time (hours/day)
    EF = Exposure Frequency (daystyear)
    ED = Exposure Duration (years)
    CF = Volumetric Conversion Factor for Water (1 L/1000 cm3)
    BW = Body Weight (kg)
    AT = Averaging Time (years)

Construction Worker Exposure: Dermal Contact with Chemicals in Surface Water
TCurrent and Future Exposures')

                     VJF -  SA x ET x EF x ED x CF
                                BW x AT x 365
             Absorbed Dose (mg/kg-day)  = HIF x PC x CW
where,
    HIF = Human Intake Factor (L/kg-day)
    CW = Chemical Concentration in Water (mg/L)
    PC = Chemical-specific Permeability Constant (cm/hr)
    SA = Skin Surface Area Available for Adult Contact (cm2)
    EF = Exposure Frequency (events/year)
    ET = Exposure Time (hours/event)
    ED = Exposure Duration (years)
    BW = Body Weight (kg)
    AT = Averaging Time (years)
    CF = Conversion Factor of 1 L/1000 cm2

Tinker AFB - Soldier Creek
Record of Decision                  6-8

-------
 Residential and Construction Worker Exposure: Dermal Contact With Chemicals in
 Sediment While Swimming and Wading (Current and Future Exposures')

                  HIF =  CF x SA x AF x ABS x EF x ED
                                  BW X AT X 365
                Absorbed Dose (mg/kg-day) =  CS x HIF
where,
    CW = Chemical Concentration in Water (mg/kg)
    CF = Conversion Factor (10"6 kg/mg)
    HIF  = Human Intake Factor (L/kg-day)
    SA = Skin Surface Area Available for Contact (cm2/event)
    AF = Soil to Skin Adherence Factor (mg/cm2)
    ABS = Absorption Factor (unitless)
    EF = Exposure Frequency (events/year)
    ED = Exposure Duration (years)
    BW = Body Weight (kg)
    AT = Averaging Time (years)

The exposure assumptions used in the baseline risk assessment for the Soldier Creek
Sediment and Surface Water Operable Unit are presented in Table 6-2 (page 6-10).
Intakes and absorbed dose values were calculated for each chemical of concern under
each exposure pathway and risk segment. Because of the large number of calculated
values, they are not presented in the ROD.  However, this information  is presented
in Appendix C of the Risk Assessment report, which is available in the Administrative
Record file.

6.5 Risk Characterization
The risk characterization quantifies present or potential future risks to human health
that may result from  exposure to the COCs found at  the operable unit. The site-
specific risk values were estimated by incorporating information from the toxicity and
exposure assessments.   When sufficient  data  are  available,  two  quantitative
evaluations are made: the incremental risk to the individual resulting from exposure
to a carcinogen; or, for  noncarcinogens, a numerical index or ratio of the exposure
dose level to an acceptable reference dose. Table 6-3 (pages 6-11 and 6-12) presents
the  total carcinogenic and noncarcinogenic risk associated with each COC.

For every segment [as shown on Figure 1-2 (page  1-3)] and each exposure pathway,
a risk was calculated. The risks associated with each pathway were summed to obtain
an  overall  noncarcinogenic and carcinogenic risk for each  segment.   A back

Tinker AFB - Soldier Creek
Record of Decision                  6-9

-------
                                             TABLE 6-2
                                    EXPOSURE ASSUMPTIONS
                                    TINKER AFB - SOLDIER CREEK
                                        RECORD OF DECISION
EXPOSURE
ASSUMPTION
Absorption Factor
Volatile Organics
Semivolatile Organics
Metal Inorganics
Averaging Time (years)
Carcinogenic
Carcinogenic (Adult Worker)
Noncarcinogenic
Body Weight (kg)
Adult Worker
Adult
Child
Contact Rate (L/hr)
Swimming
Wading
Exposure Duration (years)
Adult
Child
Exposure Frequency (day/year)
Adult Worker
Adult
Child
Exposure Time (hours/day)
Adult Worker
Adult
Child
Fraction Ingested
Ingestion Rate (mg/day)
Adult Worker
Adult
Child
Skin Surface Available for Contact
(sqcm)
Adult Worker
Adult
Child
Soil to Skin Adherence
Factor (rng/sqcnO
INGESTION OF
SEDIMENT
NA
NA
NA
70
25
30
70
57.1
15.1
NA
NA
25
5
1
4
17
NA
NA
NA
1
50
100
200
NA
NA
NA
NA
INGESTION OF
SURFACE WATER
NA
NA
NA
70
25
30
70
57.1
15.1
0.05
0.005
25
5
1
4
17
NA
2
6
NA
0.005 Uday
NA
NA
NA
NA
NA
NA
DERMAL CONTACT
WITH SEDIMENT
0.25
0.1
0.01
70
25
30
70
57.1
15.1
NA
NA
25
5
1
4
17
NA
NA
NA
NA
NA
NA
NA
9800
8620
7200
1.45
DERMAL CONTACT
WITH SURFACE WATER
NA
NA
NA
70
25
30
70
57.1
15.1
NA
NA
25
5
1
4
17
8
I-
NA %
NA
NA
NA
9800
18200
7200
NA
Legend:
NA-Not Applicable.

Notes:
(1) Exposure assumptions are for current and future exposures from swimming and wading (adult and child) or construction work (adult worker).
   If adult, child, or adult worker receptor designation is not listed, exposure assumptions are the same for each receptor.
                                                 6-10

-------
                     TABLE 6-3
SUMMARY OF TOTAL CARCINOGENIC AND NONCARCINOGENIC
       RISKS FOR EACH CONTAMINANT OF CONCERN
               TINKER AFB - SOLDIER CREEK
                  RECORD OF DECISION
Non- Carcinogenic Carcinogenic
Risk Total carcinogenic Cleanup Cleanup
Assessment Non- Total Cleanup Level Level
Concentration carcinogenic Carcinogenic Level (mg/kg) (mg/kg)
ANALYTE(a) (me/ke) Risk(b) Risk(c) ftng/keVd) fl.OOE-6)(e) (1.00E-4)(f)
SEDIMENT
ACETONE
BENZENE
CARBON D1SULFIDE
CHLOROBENZENE
CHLOROETHANE
CHLOROFORM
1 2- DICHLOROETHENE (TOTAL)
ETHYLBENZENE
METHYLENE CHLORIDE
TETRACHLOROETHENE
TRICHLOROETHENE
TOLUENE
VINYL ACETATE
XYLENE (TOTAL)
ACENAPHTHENE
ANTHRACENE
BENZO(A)ANTHRACEN;E
BENZO(A)PYRENE
BENZO(B)FLUORANTHENE
BENZO(K)FLUORANTHENE
BIS(2- ETHYLHEXYL)PHTHALATE
BENZO(GJ1J)PERYLENE
BUTYLBENZYLPHTHALATE
2-CHLORONAPHTHALENE
CHRYSENE
DIBENZ(AJ1)ANTHRACENE
DIBENZOFURAN
U-DICHLOROBENZENE
1.4-DICHLOROBENZENE
U-DICHLOROBENZENE
3.3--DICHLOR OBENZIDINE
DI-N-BUTYLPHTHALATE
DI-N-OCTYLPHTHALATE
FLUORANTHENE
FLUORENE
2-METHYLNAPHTHALENE
2-METHYLPHENOL
4-METHYLPHENOL
2.4- DIMETHYLPHENOL
INDENO(U,3-CD)PYRENE
NAPHTHALENE
PHENANTHRENE
PYRENE
ALUMINUM
ARSENIC
BARIUM
CADMIUM
CALCIUM
CHROMIUM
COBALT
COPPER
CYANIDE
IRON
LEAD
1.7E+00
5.0E-03
2.1E-02
6.1E-03
1.3E-02
2.8E-02
1.8E+01
5.0E-03
l.OE-01
5.0E-03
4.2E-01
5.0E-03
5.0E-03
5.2E-03
1.7E-01
1.7E-01
1.7E-01
2.5E-01
1.9E-01
1.8E-01
4.2E+00
1.2E+00
1.7E-01
5.0E-01
2.0E-01
1.7E-01
2.4E-01
I.8E-01
7.1E-01
5.4E-01
4.9E-01
1.7E-01
1.7E-01
3.8E-01
1.7E-01
UE+00
1.7E-01
1.7E-01
1.7E-01
1.2E+00
1.7E-01
2.6E-01
4.7E-01
1.4E+04
3.9E+00
9.JE+02
1.6E+01
43E+04
3.4E+02
2.1E+01
1.4E+02
1.8E+00
UE+04
13E+02
4.1 E- 05
3.6E-08
7.4E-07

6.8E-06
3.2E-04
8.8E-09
4.0E-06
1.2E-06

6.0E-08
l.OE-06
6.3E-09
4.4E-06
8.8E-07




3JE-04

UE-06






6.8E-07

2.6E-06
1.3E-05
1.5E-05
6.6E-06

3.7E-07
3.7E-07
9JE-07

6.6E-05

2.5E-05

1.9E-03
6.4E-03
1.5E-02

3.3E-02


2.7E-06


WE-10

L8E-10


7.8E-10
2.7E-10
2.9E-10





l.OE-07
1.5E-07
1.1E-07
1.1E-07
4.0E-08



1.2E-07
1.4E-09


6.9E-10

9.0E-09








9.6E-09














4.1E+04
5.7E+05
8.3E+03

4.1E+03
5.7E+04
5.7E+05
2.5E+04
4.1E+03

83E+04
l.OE+06
8.3E+05
3.8E+04
1.9E+05




13E+04

1.3E+05






7.9E+05

6.3E+04
1.3E+04
2.5E+04
2.5E+04

4.4E+05
4.4E+05
1.8E+05

2.5E+03

1.9E+04

2.1E+03
1.4E+05
l.OE+03

l.OE+04


6.7E+05


3.3E+01

1.6E+02


1.3E+02
1.9E+01
1.4E+03





1.6E+00
1.6E+00
1.6E+00
1.6E+00
l.OE+02



1.6E+00
1.2E+02


l.OE+03

5^E+OI








1.2E+02














3.3E+03

1.6E+04


1.3E+04
1.9E+03
1.4E+05





1.6E+02
1.6E+02
1.6E+02
1.6E+02
l.OE+04



1.6E+02
1.2E+04


l.OE+05

5.5E+03








1.2E+04














                       6-11

-------
                 TABLE 6-3 (Continued)
SUMMARY OF TOTAL CARCINOGENIC AND NONCARCINOGENIC
       RISKS FOR EACH CONTAMINANT OF CONCERN
               TINKER AFB - SOLDIER CREEK
                  RECORD OF DECISION
Risk Total
Assessment Non— Total
Concentration carcinogenic Carcinogenic
ANALYTEfa1) fme/ke) Riskfb) Riskfc)
MAGNESIUM 13E+04
MANGANESE 55E+02 2.7E-03
MERCURY 22E+QQ 3.6E-03
NICKEL 4.9E+01 1.2E-03
POTASSIUM 1.3E+03
SELENIUM 3.3E+00
SILVER 4.3E+00 6.9E-04
VANADIUM 2.6E+01 1.8E-03
ZINC 1.3E+02 3.2E-04
SURFACE WATER (&
ACBTONE 5.1E-02 l.OE-04
BENZENE 5.0E-03
BROMODICHLOROMETHANE 5.2E-03 6.2E-06
BROMOFORM 7.1E-03 3.8E-06
CARBON DISULFIDE 5.0E-03 9.4E-04
CHLOROBENZENE 5.0E-03 4.0E-04
CHLOROFORM 5.0E-03 2.5E-04
DIBROMOCHLOROMETHANE 5.0E-03 4.0E-06
U-DICHLOROETHENE (TOTAL) 8.6E-03 5.6E-05
METHYLENE CHLORIDE 5.2E-OI 3.0E-03
TETRACHLOROETHENE 5.0E-03 8.7E-05
1,1,1 -TRICHLOROETHANE 5.0E-03 4.4E-05
TRICHLOROETHENE 5.0E-03
TOLUENE 5.0E-03 8.9E-04
XYLENE(TOTAL) 5.0E-03 4.7E-07
BENZO(G,HJ)PERYLENE 5.2E-03
BENZOICAaD 5.0E-03 5.0E-05
CHRYSENE 5.0E-03
FLUORANTHENE 5.0E-03 2.3E-04
PYRENE 5.0E-03 8.5E-07
ALUMINUM 4.1E-01
ARSENIC 7.4E-03 9.2E-04
BARIUM 2.8E-01 1.1E-03
BERYLLIUM 2.5E-03 1.7E-05
CADMIUM 8JE-03 4.0E-03
CALCIUM 4.8E+01
CHROMIUM 3.5E-02 3.3E-03
COBALT 2.1 E- 01
COPPER 6.2E-01
CYANIDE 1.6E-02 3.2E-04
IRON 3.5E-01
LEAD 2.0E-02
MAGNESIUM 2.2E+01
MANGANESE 3.0E-01 8.4E-04
NICKEL 1.8E-02 3.0E-CM
POTASSIUM 63E+00
SELENIUM 6.7E-03
SILVER l.OE-02 2.8E-05
SODIUM UE+02
VANADIUM 5.0E-02 8.9E-05
ZINC 1.5E+00 1.2E-04









2.5E-07
3.0E-09
2.1E-10


6.6E-09
2.5E-09
5.9E-07
1.6E-08

1.8E-08


4.2E-09





1.3E-07

















Non- Carcinogenic Carcinogenic
carcinogenic Cleanup Cleanup
Cleanup Level Level
Level (mg/kg) (mg/kg)
(ms/kzYd) (1.00E-6He) (1.00E-4)ff)

2.1E+05
6.2E+02
4.1E+04


6.2E+03
1.4E+04
4.1E+05
5.0E+02
2.0E-02
8.4E+02 1.7E+00
1.9E+03 3.3E+01
5JE+00
1JE+01
2.0E+01 7.6E-01
1.3E+03 2.0E+00
1.5E+02
1.7E+02 8.9E-01
5.7E+01 3.1E-01
1.1E+02
2.8E-01
5.6E+00
1.1E+04
l.OE+02
1.2E+00
2.2E+01
5.9E+03

8.1E+00
2.5E+02
1.5E+02 2.0E-02
2.1E+00

1.1E+01


4.9E+01



3.5E+02
6.2E+01


3.5E+02

5.6E+02
1.3E+04









2.0E+00
1.7E+02
33E+03


7.6E+01
2.0E+02
8.9E+01
3.1E+01
,-'
2.8E+Q|


1.2E+02





2.0E+00

















a) Analytes are evaluated using the most conservative scenario for each analyte.
b) Total noncarcinogenic risks are the summation of two exposure pathways. Incidental Ingestion and Dermal Contact.
c) Total carcinogenic risks are the summation of two exposure pathways. Incidental Ingestion and Dermal Contact.
d) Cleanup Level = (Risk Assessment Concentration/nskVHI) where HI =1.0 '
e) Cleanup Level = (Risk Assessment Concentration/riskxl.OOE-6)
f) Cleanup Level = (Risk Assessment Concentration/risk)(1.00E-4)
g) Units of concentration for surface water constituents are mg/L.
6-12

-------
calculation was  performed  using the risk calculated from the most conservative
exposure scenario and the contaminant concentration to determine the risk-based
cleanup goal for each contaminant.  These cleanup levels are presented in Table 6-3
(pages 6-11 and 6-12).

6.5.1 Noncarcinogenic Risk
The EPA has developed standards, guidelines, and criteria that provide levels of
intakes  considered to protect human populations  from  possible adverse effects
resulting from chemical exposures. The ratio of the estimated chemical intake to the
RfD provides a numerical measure of the potential for adverse effects. This ratio is
referred to as the chronic hazard quotient (HQ). In the absence of federal standards,
the HQ is compared with the  most  applicable criteria or guideline for intakes.

The estimated chronic chemical intake, in mg/kg-day, is estimated using the exposure
assumptions and the actual site data. The chemical intake is then compared with the
RfD to  determine if chronic exposure to the contaminated medium presents a risk.
Because certain standards are derived for protection against either subchrom'c or
chronic exposures, chemical intakes for noncarcinogens are developed for subchronic
and chronic exposures, and the associated risks are  assessed as appropriate.

All of the HQ values for the chemicals within each exposure pathway are added
together to yield the hazard index (HI). The HI provides a useful reference point
for gauging the potential significance of multiple contaminant exposures within a
single medium or across media. A HI value of less  than 1.0 indicates little concern
for noncarcinogenic effects, and a HI value greater than or equal to 1.0 indicates an
increased level of concern.

Indices were calculated for all of the COCs at the operable unit. The results indicate
that His for all current and future human health exposures associated with Soldier
Creek  surface water and  sediment  are  less  than  1.0.    Summaries of  the
noncarcinogenic risks associated with current and future  land use of the Soldier
Creek Sediment and Surface Water Operable Unit are presented in Tables  6-4 (page
6-14) and 6-5 (page 6-15), respectively.

6.5.2  Carcinogenic Risk
For carcinogens or suspected carcinogens, a quantitative risk assessment involves
calculating risk levels considered to represent the probability or range of probabilities
of developing  additional incidence of cancer  under  the   prescribed  exposure
conditions.  Carcinogenic risk estimates, expressed as additional incidence of cancer,
are determined by multiplying  the slope factor by the projected exposure dose level.
It is the slope factor, expressed in (mg/kg-day)'1, that converts the estimated exposure
dose level, expressed in mg/kg-day, to incremental risk. These risks are probabilities
that are generally expressed in scientific notation (e.g., 1E-06). An excess lifetime

Tinker AFB - Soldier Creek
Record  of Decision                  6-13

-------
                                     TABLE 6-4
         SUMMARY OF NONCARCINOGENIC RISKS, CURRENT LAND USE
                  SURFACE WATER AND SEDIMENT EXPOSURES
                             TINKER AFB - SOLDIER CREEK
                                 RECORD OF DECISION
POPULATION
          MEDIUM
EXPOSURE PATHWAY
RISK (HI)
OFF-BASE
RESIDENTS
ON-BASE
WORKERS
SURFACE WATER - SEGMENT A

SHALLOW SEDIMENT - SEGMENT A



SURFACE WATER - SEGMENTS

SHALLOW SEDIMENT - SEGMENTS



SURFACE WATER - SEGMENTM1

SHALLOW SEDIMENT - SEGMENTM1



SURFACE WATER - SEGMENTM2

SHALLOW SEDIMENT - SEGMENTM2



SURFACE WATER - SEGMENTM3

SHALLOW SEDIMENT - SEGMENTM3



SURFACE WATER - SEGMENTE2

SHALLOW SEDIMENT - SEGMENTE2



SURFACE WATER - SEGMENTW2

SHALLOW SEDIMENT - SEGMENTW2



SURFACE WATER - SEGMENTEl

SHALLOW SEDIMENT - SEGMENTEl



SURFACE WATER - SEGMENTW1

SHALLOW SEDIMENT - SEGMENTW1
INCIDENTAL INGESTION- WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION                l.OOE-03
DERMAL CONTACT	      4.00E-03
SEGMENT A RISK (HI):                 5.00E-03

INCIDENTAL INGESTION-WADING        l.OOE-04
DERMAL CONTACT-WADING            8.00E-04
INCIDENTAL INGEST1ON                4.00E-03
DERMAL CONTACT	      l.OOE-02
SEGMENTS RISK (HI):                 2.00E-02

INaDENTALINGESTION-WADING        4.60E-04
DERMAL CONTACT-WADING            3.20E-03
WaDENTAL INGESTION                2.00E-02
DERMAL CONTACT	      6.00E-02
SEGMENTMIRISK(HI):                8J7E-02

INaDENTALINGESTION-SWIMMING       2.37E-03
DERMAL CONTACT-SWIMMING          4.93E-03
INCIDENTAL INGESTION                3.00E-03
DERMAL CONTACT	      9.00E-03
SEGMENTM2RISK(HI):                1.93E-02

INaDENTALINGESTION-SWIMMING       1.41E-02
DERMAL CONTACT-SWIMMING          2.75E-03
INaDENTAL INGESTION                l.OOE-03
DERMAL CONTACT	      4.00B-03
SEGMENTM3RISK(HI):                2.19E-02

INaDENTAL INGESTION-SWIMMING       6.77E-03
DERMAL CONTACT-SWIMMING          6.77E-03
INaDENTAL INGESTION                3.00E-03
DERMAL CONTACT	      l.OOE-02
SEGMENTE2 RISK (HI):                2.6SE-02

INODENTALINGESTION-SWIMMING       1.06E-03
DERMAL CONTACT-SWIMMING          1.83E-03
INODENTAL INGESTION                ZOOE-02
DERMAL CONTACT	      5.00E-02
SEGMENTW2 RISK (HI):                7.29E-02

maDENTAL INGESTION-SWIMMING       5.00E-06
DERMAL CONTACT-SWIMMING          7.00E-04
INaDENTAL INGESTION                2.00E-Q5
DERMAL CONTACT	      l.OOE-02
SEGMENTEl R1SK(HI):                1.07E-02

INaDENTAL INGESTION-SWIMMING       4.00E-Q5
DERMAL CONTACT-SWIMMING          4.00E-03
INaDENTAL INGESTION                aOOE-04
DERMAL CONTACT	      tOOE-02
SEGMENTWIRISK(HI):                2.00E-02
Legend:
— Indicates that a HI could not be calculated for the pathway because the stream was dry on the sampling date.
                                         6-14

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                                   TABLE 6-5
       SUMMARY OF NONCARCINOGEN1C RISKS, FUTURE LAND USE
                SURFACE WATER AND SEDIMENT EXPOSURES
                           TINKER AFB - SOLDIER CREEK
                               RECORD OF DECISION
POPULATION
         MEDIUM
EXPOSURE PATHWAY
RISK (HI)
OFF-BASE
RESIDENTS
ON-BASE
WORKERS
SURFACE WATER - SEGMENTA

DEEP SEDIMENT - SEGMENTA



SURFACE WATER - SEGMENTB

DEEP SEDIMENT - SEGMENTB



SURFACE WATER - SEGMENT Ml

DEEP SEDIMENT - SEGMENTM1



SURFACE WATER - SEGMENT M2

DEEP SEDIMENT- SEGMENTM2



SURFACE WATER - SEGMENTM3

DEEP SEDIMENT - SEGMENTM3



SURFACE WATER - SEGMENTE2

DEEP SEDIMENT- SEGMENTE2



SURFACE WATER - SEGMENTW2

DEEP SEDIMENT - SEGMENTW2



SURFACE WATER - SEGMENTEl

DEEP SEDIMENT - SEGMENTEl



SURFACE WATER - SEGMENTW1

DEEP SEDIMENT - SEGMENT Wl
INCIDENTAL INGESTJON -WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION
DERMAL CONTACT	          —
SEGMENTA RISK (HI):

INCIDENTAL INGESTION -WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION
DERMAL CONTACT	          --
SEGMENT B RISK (HI):

INaDENTAL INGESTTON-WADING         4.60E-04
DERMAL CONTACT-WADING             3.20E-Q3
INCIDENTAL INGESTION                 1.30E-02
DERMAL CONTACT	      4.00E-02
SEGMENTM1 RISK (HI):                 5.67E-02

maDENTAL INGESTION-SWIMMING       237E-03
DERMAL CONTACT-SWIMMING           4.93E-03
INaDENTAL INGESTION                 5.20E-03
DERMAL CONTACT	      2.00E-02
SEGMENTM2 RISK (HI):                 3.2SE-02

INaDENTAL INGESTTON-SWIMMING       1.41E-Q2
DERMAL CONTACT-SWIMMING           2.75E-03
INCIDENTAL INGESTION                 7.KE-04
DERMAL CONTACT	      2.00E-03
SEGMENTM3 RISK (HI):                 1.96E-02

INQDENTALINGESTION-SWIMMING       6.77E-03
DERMAL CONTACT-SWIMMING           6.49E-03
INaDENTAL INGESTION                 3.50E-03
DERMAL CONTACT	      l.OOE-02
SEGMENTE2RISK(HI):                 2.68E-02

maDENTALINGESTION-SWlMMING       1.06E-03
DERMAL CONTACT-SWIMMING           1.83E-03
INaDENTAL INGESTION                 1.20E-02
DERMAL CONTACT	      4.00E-02
SEGMENTW2 RISK (HI):                 5.49E-02

INODENTAL INGESTION-SWIMMING       5.00E-06
DERMAL CONTACT-SWIMMING           7.00E-04
maDENTAL INGESTION                 5.00E-04
DERMAL CONTACT	      7.00E-03
SEGMENTEl RISK (HI):                 8.21E-03

INaDENTAL mOESTION-SWIMMING       4.00E-05
DERMAL CONTACT-SWIMMING           4.00E-03
maDENTAL INGESTION                 3.00E-04
DERMAL CONTACT	       5.00E-03
SEGMENTWIRISK(HI):                 l.OOE-02
Legend
- - Indicates that a HI could not be calculated for the pathway because the stream was dry on the sampling date.
                                      6-15

-------
cancer risk of 1E-06 indicates that, as a plausible upper bound, one additional case
of cancer per one  million population occurs as a result of site-related  exposure
conditions.   The 1E-06 risk  is used as  a point of departure  for  determining
remediation goals for alternatives when ARARs are not available or sufficiently
protective because  of the presence of multiple contaminants at a site or multiple
pathways of exposure.  EPA has determined that remedial actions should  minimize
the risk at a site so that it falls within a range of 1E-04 (one additional case  of cancer
per ten thousand) to  1E-06.  This is considered to be a generally acceptable risk
range.  The  risk assessment for the Soldier Creek Sediment and Surface Water
Operable Unit indicated that the carcinogenic risks for all current  and  future RME
exposures associated with the surface water and sediment are within this  specified
risk range in  the absence of conducting an intrusive remedial action at  the operable
unit. Summaries of the carcinogenic risks associated with current and future land use
of the Soldier Creek Sediment and Surface Water Operable Unit  are  presented in
Tables 6-6 (page 6-17) and 6-7 (page 6-18), respectively.

6.5.3 Environmental Evaluation
The qualitative environmental assessment conducted  as a part of  the  baseline risk
assessment   included  selecting  COCs,  exposure   characterization, and  risk
characterization.  Because detailed field  surveys and  toxicity testing were not
conducted during the RI, it was difficult to estimate the risk of site contaminants to
aquatic and terrestrial species that inhabit the Soldier Creek Sediment and Surface
Water Operable Unit ecosystem. The assessment focused on the effect  of the COCs
on general populations of species that are typically found in the operable unit area.
The COCs were selected on the basis of positive identification in samples  collected
during the RI with  special consideration for those chemicals that have the greatest
potential for injury  to environmental receptors or that are toxic to animals.  The
exposure characterization identified potential receptors and exposure  pathways  of
contaminant  migration  to  these receptors.  Receptors identified included  birds,
mammals, amphibians, reptiles, and plants  documented or expected to  occur in the
area of the Soldier  Creek Sediment and Surface Water Operable Unit.  Exposure
pathways for each  type of receptor were identified and included dermal contact,
ingestion, inhalation, and respiration.  The qualitative risk characterization evaluated
the potential risks to aquatic and terrestrial species.  The presence of  some metals
in Soldier Creek may present an environmental concern to aquatic species;  however,
this cannot be fully evaluated without conducting a quantitative ecological assessment.
More information is also needed to fully define the risk to terrestrial inhabitants.  A
more detailed discussion of the  environmental  evaluation is presented in the risk
assessment report, which is available in the Administrative Record file.
Tinker AFB - Soldier Creek
Record of Decision                  6-16

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                                        TABLE 6-6
             SUMMARY OF CARCINOGENIC RISKS, CURRENT LAND USE
                    SURFACE WATER AND SEDIMENT EXPOSURES
                               TINKER AFB - SOLDIER CREEK
                                   RECORD OF DECISION
POPULATION
           MEDIUM
EXPOSURE PATHWAY
RISK
OFF-BASE
RESIDENTS
ON-BASE
WORKERS
SURFACE WATER - SEGMENTA

SHALLOW SEDIMENT - SEGMENTA



SURFACE WATER - SEGMENTS

SHALLOW SEDIMENT - SEGMENTS



SURFACE WATER - SEGMENT Ml

SHALLOW SEDIMENT - SEGMENT Ml



SURFACE WATER - SEGMENT M2

SHALLOW SEDIMENT - SEGMENTM2



SURFACE WATER - SEGMENTM3

SHALLOW SEDIMENT- SEGMENT M3



SURFACE WATER - SEGMENTE2

SHALLOW SEDIMENT- SEGMENTE2



SURFACE WATER - SEGMENTW2

SHALLOW SEDIMENT- SEGMENT W2



SURFACE WATER - SEGMENTE1

SHALLOW SEDIMENT - SEGMENTE1



SURFACE WATER - SEGMENT Wl

SHALLOW SEDIMENT - SEGMENT Wl
INCIDENTAL INGESTION- WADING
DERMAL CONTACT-WADING
INCIDENTAL INGEST1ON                    4.60E-07
DERMAL CONTACT	      5.00E-09
SEGMENTA RISK:                         4.65E-07

INCIDENTAL INGESTION -WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION                    4.80E-10
DERMAL CONTACT	      7.00E-09
SEGMENTS RISK:                         7.48E-09

INCIDENTAL INGESTION -WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION                    3.60E-10
DERMAL CONTACT	      4.00E-09
SEGMENTM1 RISK:                        4.36E-09

INCIDENTAL INGESTION -SWIMMING           1.50E-OS
DERMALCONTACT-SWIMMING               2JOE-07
INCIDENTAL INGESTION                    2.00E-07
DERMAL CONTACT	      6.0aE-09
SEGMENTM2 RISK:                        4.71E-07

mCIDENTALINGESnON-SWIMMING           Z20E-09
DERMALCONTACT-SWIMMING               4.37E-09
INCIDENTAL INGESTION                    2.70E-10
DERMAL CONTACT	      4.00E-P9
SEGMENTM3 RISK:                        1.08E-08

INCIDENTAL INGESTION -SWIMMING           3.00E-07
DERMALCONTACT-SWIMMING               5.40E-07
INCIDENTAL INGESTION                    4.90E-10
DERMAL CONTACT	      6.00E-09
SEGMENTE2RISK:                         8.46E-07

INCIDENTAL INGESTION-SW1MMING
DERMALCONTACT-SWIMMING
INCIDENTAL INGESTION                    5.60E-07
DERMAL CONTACT	      4.00E-08
SEGMENTW2 RISK:                        6.00E-07

INCIDENTAL INGESTION                    4.00E-09
DERMAL CONTACT                        2.0QE-08
INCIDENTAL INGESTION                    8.00E-08
DERMAL CONTACT	      9.00E-08
SEGMENTE1 RISK:                         1.94E-07

INCIDENTAL INGESTION                    8.00E-10
DERMAL CONTACT                        l.OOE-07
INCIDENTAL INGESTION                    l.OCE-07
DERMAL CONTACT	     3.00E-08
SEGMENTW1 RISK:                        3.00E-07
Legend:
— Indicates that a risk could not be calculated for the pathway because the stream was dry on the sampling date or (hat the contaminants
  detected in the segment do not pose a carcinogenic health risk.
                                           6-17

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                                        TABLE 6-7
               SUMMARY OF CARCINOGENIC RISKS, FUTURE LAND USE
                     SURFACE WATER AND SEDIMENT EXPOSURES
                                TINKER AFB - SO1JDIER CREEK
                                    RECORD OF DECISION
POPULATION   MEDIUM
                                EXPOSURE PATHWAY
                                    RISK
OFF-BASE
RESIDENTS
ON-BASE
WORKERS
SURFACE WATER - SEGMENTA

DEEP SEDIMENT - SEGMENTA



SURFACE WATER - SEGMENTS

DEEP SEDIMENT - SEGMENTS



SURFACE WATER - SEGMENTM1

DEEP SEDIMENT- SEGMENT Ml



SURFACE WATER - SEGMENT M2

DEEP SEDIMENT - SEGMENTM2



SURFACE WATER - SEGMENTM3

DEEP SEDIMENT- SEGMENTM3



SURFACE WATER - SEGMENTE2

DEEP SEDIMENT - SEGMENTE2



SURFACE WATER - SEGMENTW2

DEEP SEDIMENT - SEGMENTW2



SURFACE WATER - SEGMENTE1

DEEP SEDIMENT - SEGMENTE1



SURFACE WATER - SEGMENTW1

DEEP SEDIMENT - SEGMENTW1
INCIDENTAL INGESTION-WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION
DERMAL CONTACT	          --
SEGMENTA RISK:

INCIDENTAL INGESTION-WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION
DERMAL CONTACT   .	          —
SEGMENTS RISK:

INCIDENTAL INGESTION-WADING
DERMAL CONTACT-WADING
INCIDENTAL INGESTION                    3.47E-10
DERMAL CONTACT	      4.00E-09
SEGMENTM1 RISK:                        435E-09

INCIDENTAL INGESTION-SWIMMING          1.68E-08
DERMAL CONTACT-SWIMMING              2^8E-07
INCIDENTAL INGESTION                    1.51E-07
DERMAL CONTACT	      5.00EjHQ9
SEGMENTM2 RISK:                        431El

INaDENTAL INGESTION-SWIMMING          2.22E-
DERMALCONTACT-SWIMMING              4J7E-09
INQDENTAL INGESTION                    4.87E -10
DERMAL CONTACT	      6.00E-09
SEGMENTM3RISK:                        131E-08

INQDENTAL INGESTION-SWIMMING          2.9SE-G7
DERMAL CONTACT-SWIMMING              5.40E-07
INQDENTAL INGESTION                    4.57E-10
DERMAL CONTACT	      6.00E-09
SEGMENTE2 RISK:                        8.41E-07

INCIDENTAL INGESTION-SWIMMING
DERMAL CONTACT-SWIMMING
INaDENTAL INGESTION                    S.31E-07
DERMAL CONTACT	      4.00E-06
SEGMENTW2RISK:                        5.91E-07

INQDENTAL INGESTION                    4.00E-09
DERMAL CONTACT                        2.00E-08
INaDENTAL INGESTION                    5.00E-08
DERMAL CONTACT	      4.00E-08
SEGMENTE1 RISK:                        1.14E-07

INQDENTAL INGESTION                    8.OE-10
DERMAL CONTACT                        l.OQE-07
INODENTAL INGESTION                    8.00E-08
DERMAL CONTACT	      2.00E-08
SEGMENTW1 RISK:                        2.01E-07
Legend:
— Indicates that a risk could not be calculated for the pathway becuase the stream was dry on the sampling dale or that the contaminants detected,^•
   in the segment do not pose a carcinogenic health risk.                                                      r'
                                            6-18

-------
 The  environmental assessment  also  identified the  potentially  threatened  or
 endangered species that are likely to inhabit, or are known to inhabit, the area of
 Tinker AFB and the Soldier Creek Sediment and Surface Water Operable Unit.
 These include the Oklahoma beardtongue, Ozark poverty grass, the Prairie mole
 cricket, Swainson's hawk, and the Texas horned lizard.

 One jurisdictional wetland exists along East Soldier Creek in the  area of the IWTP.
 The wetland is the result of a manmade structure and is not considered by the State
 of Oklahoma to be an official wetland area.

 6.5.4 Uncertainties
 Regardless of the type of risk estimate developed, it should be emphasized that all
 estimates of risk are based upon numerous assumptions and uncertainties.   The
 factors  that contribute  uncertainty include  the  estimates  of   the  exposure
 concentrations,  daily intakes,  and toxicity information.  These factors  include
 chemicals not  included in  the assessment,  exposure pathways not  considered,
 derivation of exposure point concentrations, intake uncertainty, lexicological dose-
 response  and  toxicity  value   uncertainty,  and  synergistic  effects of  multiple
 contaminants.

 The quantitative risk characterization processes that were identified as contributing
 uncertainty to the risk assessment include  the fact that the slope factors used to
 calculate oral carcinogenic risks for carcinogenic polynuclear aromatic hydrocarbons
 (PAH) compounds were based on benzo(a)pyrene.  There are  also uncertainties
 associated with summing cancer risks or hazard indices for different chemicals. This
 assumption  of  dose additivity  ignores  possible  synergism or antagonism among
 chemicals and differences in mechanisms of action and metabolism. It is not known
 what effects these uncertainties have on  the total risk estimation.

 Another  important uncertainty concerns the fact that  risk calculations for dermal
 exposure to carcinogenic PAHs were not performed. It is likely that risk for exposure
 to carcinogenic PAHs is underestimated. However, because carcinogenic PAHs are
 not one  of  the primary contributors to carcinogenic  risk at the Soldier Creek
 Sediment and  Surface  Water  Operable  Unit,  these  factors are  relatively  less
 important in the overall view of risk levels. These uncertainties and the uncertainties
 discussed in  previous sections need to be considered when evaluating the results of
 the risk assessment and when making risk management decisions for the operable
 unit.

 EPA risk assessments are  required to consider a "central tendency exposure" and
 "high end exposure." The central tendency exposure is the average exposure that is
 expected to  occur at the  site.  The CERCLA  RME  is considered a  "high end
 exposure." The RME exposure is the maximum exposure that is reasonably expected

Tinker AFB - Soldier Creek
Record of Decision                  6-19

-------
to occur at a site.  The  central tendency exposure provides an indication of the
degree of uncertainty in the risk assessment.

Use RME exposure assumptions in the baseline risk assessment resulted in excess
cancer risks of less than one excess cancer in one million individuals (1E-06). The
EPA acceptable risk range specified in the NCP is one excess cancer in ten thousand
individuals  (1E-04).   Using central  tendency exposure assumptions in the risk
assessment would result in even lower risk estimates by approximately a factor of
four.  Therefore, the risk assessment using either exposure regime would result in
excess cancer risks less than one excess cancer in one million individuals (1E-06), the
lower end of EPA acceptable risk range.

6.5.5 Cleanup Goals
The cleanup, or remediation, goals presented in Table 6-3 (pages 6-11 and 6-12) are
the risk-based levels that determine the extent of site media requiring remediation.
For example, sediment that exceeded the 1E-04 carcinogenic cleanup level or the
noncarcinogenic cleanup level would require some form of remediation. The 1E-06
carcinogenic cleanup level is the point of departure for determining if remediation
is  required at  a site.  For values that fall within  the range of 1E-04 and  1E-06,
cleanup may be necessary depending upon site and contaminant characteristics, such
as frequency of detections above the cleanup goals.  None of the sediment or surface
water at the Soldier  Creek  Sediment and Surface Water Operable Unit have
contaminant concentrations exceeding these cleanup goals (1E-04 cleanup level).

The general cleanup level for PCBs in soil in an unrestricted access area is 10 ppm
and in a restricted access area is 25 ppm. Although Tinker AFB could be classified
as a restricted access area, the sample results were less  than the criterion for an
unrestricted access area (i.e., 10 ppm). Because the concentrations of PCB-1254 are
below the general cleanup levels for an unrestricted access area, including PCBs as
a sampling parameter within the selected alternative would be an adequate means
of protecting human health and the  environment.  The general cleanup level for
PCBs in sediment, if found, would be determined by an ecological risk assessment
considering food chain effects.

6.5.6 Conclusion
None of the sediment or surface water contaminants detected in Soldier Creek during
Phase I and II of the RI were detected at concentrations that exceeded the allowable
carcinogenic risk range (1E-04 to 1E-06) or the noncarcinogenic HI of 1.0.

Because concentrations  of  several  organic  and inorganics  were detected at
background sampling locations, a "background" cancer risk is present for Soldier
Creek sediment and surface water. However, because the values do not exceed the
Tinker AFB - Soldier Creek
Record of Decision                  6-20

-------
 1E-06 cancer risk level, the sediment and surface water do not present a threat to
 human health or the environment.

 Actual or threatened migration  of hazardous substances  from  the Soldier Creek
 Sediment and Surface Water Operable Unit, if not addressed by implementing the
 response action selected in this ROD, may potentially present an endangerment to
 public health, welfare, or the environment. The proposed response action will insure
 that any  migration  of  contaminants from the operable  unit  at concentrations
 exceeding the risk-based cleanup levels established by EPA will be addressed through
 remedial action.
Tinker AFB - Soldier Creek
Record of Decision                  6-21

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               7.0  DESCRIPTION  OF ALTERNATIVES

The six sediment and surface water (SSW) alternatives that were evaluated in detail
in the FS report are described below. This discussion identifies engineering and
treatment  components,  institutional  controls,   quantities  of  waste  handled,
implementation requirements, risk reduction, the estimated  implementation time
frame, and the primary applicable  or  relevant and  appropriate  requirements
(ARARs) associated with each option. A detailed discussion of the alternatives is
found in the FS report, which is part of the Administrative Record file.

Inherently, the removal, containment, or treatment of site media would offer the
greatest protection to human  health and the environment;  however, the action
alternatives that disturb the creek's environment could damage the aquatic ecosystem
in Soldier Creek.  Based on the qualitative environmental assessment conducted as
a part of the baseline risk assessment and because the concentrations of the sediment
and surface water COCs are not above the risk-based levels, an unacceptable risk to
human health and the environment from site media in its existing condition does not
exist.

7.1  SSW Alternative 1-No Action
    •   Capital Cost:  Not Applicable.
    •   O
-------
7.2  SSW Alternative 2-Limited Action
   •   Capital Cost: Not Applicable.
   •   O&M  Cost: $175,800 (years  1 and 2); $84,100 (years 3-5).
   •   Present Worth:  $534,800.
   •   Implementation Time: Five Years (minimum).

This alternative would consist of implementing a five-year environmental monitoring
program of Soldier Creek sediment and surface water.  Sediment and surface water
samples would  be collected along East and West Soldier Creeks.  Sampling would be
conducted on  a  quarterly basis  during  the  first two  years of monitoring and
semiannually during the last three years of monitoring. An ecological investigation
of Soldier Creek sediment and surface water would also  be conducted as a part of
the environmental monitoring program to fully determine the effects of contaminant
concentrations  on the biological environment of the creek.  The investigative activities
of the monitoring program would be used  to determine if a risk to human health or
the environment develops at the operable unit.

Statutorily required five-year reviews  would be conducted  to ensure  that no
unacceptable exposures occur as specified  in the NCP.  If an unacceptable exposure
develops at the operable unit, one of the other alternatives for remediation would be
implemented at the operable unit.

The selected remedy would be implemented to comply with the federal and state
action-specific  ARARs for the operable unit. These ARARs include the following:
   •   Resource Conservation and Recovery Act (RCRA).
           Hazardous Waste Management Systems General (Part 260).
           Identification and Listing of Hazardous Waste (Part 261).
           Standards Applicable to the Generators of Hazardous Waste (Part 262).
           Standards Applicable to Transporters of Hazardous Waste (Part 263).
           Standards Applicable to  Owners and Operators of Hazardous Waste
           Treatment, Storage, and Disposal  Facilities (Part 264).
           Land Disposal  Restrictions (Part 268).
           Hazardous Waste Permit Program (Part 270).
   •   Hazardous Materials Transportation Act.
   •   Oklahoma Controlled Industrial Waste Disposal  Act.
   •   Oklahoma Pollution Control Coordinating Act of 1968.
   •   Occupational Safety and Health Act (OSHA).

The contaminant-specific ARARs for the operable unit include  the following:
   •   Risk-Based Cleanup Levels.
   •   RCRA-Identification and Listing of Hazardous Waste (Part 261).
   •   Oklahoma Water Quality Standards (WQS).
   •   Ambient Water Quality Criteria (AWQC).

Tinker AFB - Soldier Creek
Record of Decision                  7-2

-------
Several surface water constituents exceeded the Oklahoma WQS and the AWQC
during Phases I and II of the RI. However, sediment and surface water monitoring
would be adequate to determine if an unacceptable risk develops at the operable unit
and if the surface water constituents continue to exceed the Oklahoma WQS and the
AWQC. Currently, there are no location-specific ARARs for the Soldier  Creek
Sediment and Surface Water Operable Unit. The location-specific ARARs would be
reviewed throughout the remedial process and the status changed if data indicate a
potential problem.

The estimated implementation time of this alternative is five years. No reduction in
the risk associated with site media would result from implementing this alternative;
however, an  unacceptable risk does not exist for the operable unit in its present
condition. A detailed description of this alternative, the selected remedy, is presented
in Section 9.0.

7.3  SSW Alternative 3-Capping
    •    Capital Cost:  $1,985,200.
    •    O&MCost:  $48,100.
    •    Present Worth:  $2,193,400.
    •    Implementation Time:  Nine months.

SSW  Alternative 3 would involve the construction of a concrete-lined channel over
on-base portions of East and West Soldier Creeks to minimize contaminant migration
between the sediment, surface water, and groundwater at the operable unit. Surface
water would be removed from Soldier Creek before the channel was constructed.

Temporary berms and pumps would be used to capture the surface water. The water
would be  transferred  to  a  mobile,  on-base treatment  system for treatment.
Treatment  residuals would be disposed of as  hazardous waste. After meeting the
discharge standards, the treated surface water could be discharged to Soldier Creek
downstream of the construction area or put  to  beneficial use at the Base.  The
discharge standards would be the Oklahoma WQS. Approximately 655,000 gallons
of surface water would be treated during construction of the concrete-lined channel.

After completion of the concrete-lined channel and restoration of Soldier Creek to
its original flow path, Soldier Creek surface water would be periodically monitored
to determine the effectiveness of the capping system.  Surface water monitoring
would be conducted on an annual basis for a five-year period in the areas where the
channel was  constructed.   Sediment and surface water monitoring would be
performed at off-base locations. The final selection of these sampling locations would
be agreed upon by Tinker AFB, the EPA, and the OSDH, and would be made during
remedial design.  The results of the  monitoring program would also be reviewed to
Tinker AFB - Soldier Creek
Record of Decision                   7.3

-------
determine  potential  interrelationships  between  sediment,  surface water,  and
groundwater constituents.

This action-specific ARARs for the operable unit include the following:
    •   RCRA.
           Criteria for the Classification of Solid Waste Disposal and Facilities and
           Practices (Part 257).
           Hazardous Waste Management Systems Genera] (Part 260).
           Identification and Listing of Hazardous Waste (Part 261).
           Standards Applicable to the Generators of Hazardous Waste (Part 263).
           Standards Applicable to  Owners and  Operators of Hazardous Waste
           Treatment, Storage,  and Disposal Facilities (Part 264).
       -   Land Disposal Restrictions (LDRs) (Part 268).
           Hazardous Waste Permit Program (Part 270).
    •   Hazardous Materials Transportation Act.
    •   Oklahoma  Controlled Industrial Waste Disposal Act.
    •   Clean Water Act—National Pollutant Discharge Elimination System.
    •   Oklahoma  Water Pollution Control Laws.
    •   Oklahoma  Pollution control Coordinating Act of 1968.
    •   Clean Air Act National Ambient Air Quality Standards (NAAQS).
    •   Oklahoma  Clean Air Act.
    •   OSHA.

The following are the federal and state contaminant-specific ARARs that pertain to
SSW Alternative 3:
    •   Oklahoma  Water Quality Standards.
    •   Risk-based Cleanup Levels.
    •   RCRA (Parts 261 and 268).
    •   Oklahoma  Controlled Industrial Waste Disposal Act.
    •   Clean Air Act - NAAQS; Regulations on National Emission Standards for
       Hazardous Air Pollutants.
    •   Oklahoma  Clean Air Act/Oklahoma Air Pollution Regulations.
    •   EPA Designation, Reportable Quantities, and Notification.

This alternative would meet all of the state and federal contaminant-specific ARARs
and would be implemented in a manner that would not cause  the action-specific
ARARs to be violated.  There are no location-specific ARARs for the Soldier Creek
Sediment and Surface Water Operable Unit. The location-specific ARARs would be
reviewed throughout the remedial process and the status changed if data indicate a
potential problem.

The estimated implementation time of this alternative is nine months.  Capping the
on-base portions of Soldier Creek would lower the risk associated with operable unit

Tinker AFB - Soldier Creek
Record of Decision                   7.4

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media; however, an unacceptable risk does not exist for the operable unit in its
present condition.

7.4   SSW  Alternative  4-Sediment Excavation and  Off-Base
Landfill Disposal
    •  Capital Cost: $2,542,300.
    •  O&MCost: $47,600.
    •  Present Worth: $2,748,400.
    •  Implementation Time:  Nine months.

SSW Alternative 4 would involve the excavation of sediment in on-base portions of
East and West Soldier Creeks. Excavated sediment would be transported to an off-
base RCRA hazardous waste landfill for disposal.

Surface water would be removed from Soldier Creek before sediment excavation.
The water would be removed and treated as described under the capping alternative.
Approximately 530,000 gallons of surface water  would require treatment during
alternative implementation. Approximately 5,630 cubic yards of sediment would be
excavated from East and West Soldier Creeks. Soldier Creek sediment and surface
water would be  monitored  annually for a  five-year period to determine  the
effectiveness of the remedial action.  Samples would be collected and analyzed, and
a five-year review would be performed, as described under the capping alternative.

The contaminant-specific and action-specific ARARs would be the same as for SSW
Alternative 3.   Compliance with the LDRs  should be achieved in  the sediment
without treatment because of the low concentrations of contaminants in the medium.
After treatment, the surface water treatment residuals should not exceed the LDR
requirements.   If the LDR levels  were exceeded,  the sediment and treatment
residuals  would undergo further treatment before disposal. This alternative would
meet all of the state and  federal  contaminant-specific ARARs and  would be
implemented in a manner that would not cause the  action-specific ARARs to be
violated.  There are no location-specific ARARs for the Soldier Creek Sediment and
Surface Water Operable Unit.  The location-specific ARARs would  be reviewed
throughout the remedial process and the status changed if data indicate a potential
problem.

The estimated implementation time of this alternative is nine months.  Removal of
sediment from the on-base portions of Soldier Creek would reduce or eliminate the
risk associated with site media; however, an unacceptable risk does not exist for the
operable  unit in its present condition.
Tinker AFB - Soldier Creek
Record of Decision                  7-5

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7.5  SSW Alternative 5-Sediment Excavation, Stabilization,  and
Off-Base Landfill  Disposal
   •   Capital Cost:  $5,708,600.
   •   O&MCost:  $47,600.
   •   Present Worth:  $5,914,700.
   •   Implementation Time: Ten months.

SSW Alternative 5 would be the same as SSW Alternative 4 except that under this
alternative, the sediment would be stabilized before it is transported to an off-base
RCRA hazardous waste landfill for disposal.

The stabilization process consists of mixing the sediment with water and compounds
that immobilize the contaminants in the sediment matrix. A treatability study would
be conducted before the remedial action is implemented to determine operational
parameters.  A treatment and curing area and an area for stockpiling reagents and
contaminated sediment would be required to implement this alternative. Samples of
the cured, stabilized mass would undergo tests to evaluate the long-term stability of
the material. The stabilization process would increase the volume approximately 5
to 60 percent, depending upon  the additives and amount of water used.   For
estimating the cost of this alternative, it was assumed that the stabilization process
would increase the excavated sediment volume by 20 percent.

The contaminant-specific and action-specific ARARs would be the same as for SSW
Alternative 3. This alternative would meet all of the state and federal contaminant-
specific ARARs and would be implemented in a manner that would not cause the
action-specific ARARs to be violated. There are no location-specific ARARs for the
Soldier Creek Sediment and Surface Water Operable Unit. The location-specific
ARARs would be reviewed throughout the remedial process and the status changed
if data  indicate a potential problem.

The estimated implementation time of this alternative is ten months. Removal of
sediment from the on-base portions of Soldier Creek would reduce or eliminate the
risk associated with site media; however, an unacceptable risk does not exist for the
operable  unit in its present condition.

7.6  SSW Alternative 6--Sediment Excavation  and Soil Washing
   •   Capital Cost:  $6,371,600.
   •   O&MCost:  $47,600.
   •   Present Worth:  $6,577,700.
   •   Implementation Time: Fourteen months.
Tinker AFB - Soldier Creek
Record of Decision                  7-6

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SSW Alternative 6 would be the same as SSW Alternative 4 except that soil washing
would be used to remediate the excavated sediment before it is transported to an off-
base RCRA hazardous waste landfill for disposal.

The soil washing process involves removing contaminants from the sediment particles
in a mobile treatment unit using water, surfactants, and other additives, if necessary.
A treatability study would be performed before implementation  to determine the
effectiveness of the soil washing process on the sediment  and to determine any
additives required to treat the sediment.  A staging area would be required for
treatment.  The treatment residuals would be  disposed of at  an off-base  RCRA
hazardous waste landfill.  Treatment process water remaining after the soil  wash
process is completed would be treated in the mobile, on-base treatment system. Soil
washing is an innovative treatment technology whose reliability is not entirely proven.

The contaminant-specific and action-specific ARARs would be the same as for SSW
Alternative 3. This alternative would meet all of the state and federal contaminant-
specific ARARs and would be  implemented in a manner that would not cause the
action-specific ARARs to be violated.  There are no location-specific ARARs for the
Soldier Creek Sediment and Surface  Water Operable Unit.  The location-specific
ARARs would be reviewed throughout the remedial process and the status changed
if data indicate  a potential problem.

The estimated implementation time of this alternative is fourteen months. Removal
of sediment from the on-base portions of Soldier Creek would reduce or eliminate
the risk associated with site media; however, an unacceptable risk does not exist for
the operable unit in its present condition.
Tinker AFB - Soldier Creek
Record of Decision                   7.7

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8.0  SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

 The NCP has established nine  evaluation criteria to address CERCLA statutory
 requirements and the technical, cost, and institutional considerations associated with
 a remedial alternative that the EPA has  determined appropriate.  The evaluation
 criteria are the basis for conducting the detailed alternative analysis in the FS report
 and for selecting the final remedy for the operable unit.  The results of comparing
 the preferred alternative and the other remedial alternatives with the following nine
 evaluation criteria are addressed in this section:
    •   Overall protection of human health and the environment.
    •   Compliance with ARARs.
    •   Long-term effectiveness and permanence.
    •   Reduction of toxicity, mobility, or volume through treatment.
    •   Short-term effectiveness.
    •   Implementability.
        Cost.
    •   State acceptance.
    •   Community acceptance.

 The first two criteria  are  threshold criteria.  These criteria must be met for an
 alternative to be considered a remedy for  a operable unit. The next five criteria are
 considered  balancing criteria. Tradeoffs are made among alternatives with respect
 to these criteria. The last two criteria are considered modifying criteria and are used
 to identify the preferred alternative after  the public comment period.

 8.1   Overall Protection of Human Health and Environment
 The selected remedy for the operable unit will not involve the remediation of Soldier
 Creek sediment and surface water as is proposed under SSW Alternatives 3,4,5, and
 6.  Inherently,  the removal, containment, or treatment of site media offers the
 greatest protection to  human health and  the environment; however,  based on the
 qualitative  environmental  assessment  conducted as a  part  of the  baseline  risk
 assessment and because the concentrations of  the sediment  and  surface water
 chemicals of concern are not above the risk-based cleanup goals established by EPA,
 an unacceptable risk to human health  and the environment from site media in its
 present condition does  not  exist.  Therefore, remediation of this  media  is not
 necessary at this time. The selected remedy will provide monitoring (quarterly for
 the first two years and semi-annually for the next three years of monitoring) of site
 media to determine if an unacceptable sediment or surface water risk develops at the
 operable unit and, therefore, will be more protective  of human health and the
 environment than SSW  Alternative  1, the  no action alternative.  In addition, a
 quantitative environmental assessment will be conducted to fully determine the affect
 of site contaminants on the Soldier Creek biological environment. The short-term


 Tinker AFB - Soldier Creek
 Record of Decision                   8-1

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effects to the public residing in the vicinity of the operable unit, Base employees, the
sediment and surface water sampling team, and the environment from implementing
the preferred alternative will be insignificant compared with the potential short-term
impacts associated with implementing an intrusive remedy at the operable unit.

8.2  Compliance with ARARs
Several surface water constituents exceeded the Oklahoma WQS and the  AWQC
during Phases I and II of the RI. However, sediment and surface water monitoring
will be adequate to determine if an unacceptable risk develops  at the operable unit
and if the surface water constituents continue to exceed the Oklahoma WQS and the
AWQC.  Sediment and surface water monitoring will be adequate to determine if a
significant risk develops at the operable unit. SSW Alternative 2 will be implemented
to comply with all of the federal and state action-specific ARARs for the operable
unit.  There are  no location-specific ARARs for the  Soldier Creek Sediment and
Surface Water Operable unit; however, these ARARs will be reviewed throughout
the remedial process and the status changed if necessary.  All of the alternatives
involving intrusive remediation would comply with the contaminant-specific ARARs
and would be conducted to comply with their associated action-specific ARARs. The
LDRs would be applicable to any alternative that involved the treatment of sediment
or surface water (SSW Alternatives 3, 4, 5, and  6) because listed wastes were found
at the Soldier Creek Sediment and Surface Water Operable Unit, or if treatment
residuals  exhibit any of the RCRA characteristics. A listed waste is a waste that is
hazardous because it is named on one of three lists developed by EPA (non-specific
source wastes, specific source  wastes, and commercial chemical products).   A
characteristic waste is  one that  exhibits the properties of ignitability, corrosivity,
reactivity, or toxicity as defined by EPA,  and is therefore considered a hazardous
waste. The treatment residuals should not exceed the LDR requirements; however,
if the residuals do exceed the LDRs, the residuals would require further treatment
before land disposal.

8.3  Long-Term Effectiveness and Permanence
There will be no long-term unacceptable risk to human health or the environment
from Soldier Creek sediment or surface water  from implementing the selected
remedy as long as the concentrations of the chemicals of concern in the operable unit
media do not exceed the risk-based cleanup levels. The risk to the environment will
be fully evaluated by conducting an ecological investigation of Soldier Creek.  SSW
Alternative  2 will provide  long-term effectiveness by detecting any increases in
contaminant concentration  and  risk.   Ideally, the alternatives that  involve  the
containment or treatment of sediment  and the treatment of surface water (SSW
Alternatives 3,  4, 5, and 6) afford a greater amount of long-term effectiveness and
permanence; however,  based on the current conditions in Soldier Creek, this is not
required for the sediment and surface water in the stream.  SSW Alternative 3, which
involves the capping of on-base portions of Soldier Creek, would not be as

Tinker AFB - Soldier Creek
Record of Decision                   8-2

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permanent as the other intrusive alternatives because  sediment would  not  be
removed from the creek and treated or disposed of. The selected remedy will be
more protective  of the public and the environment than  the no action alternative
because  monitoring will indicate  if a significant  sediment or surface water risk
develops at the operable unit and will determine the migration or persistence of the
chemicals of concern in these media.  Changes in the condition of Soldier Creek
sediment and surface water could not be determined under the no action alternative
because the statutory five-year review does not include sampling of operable unit
media. If a risk to human health and the environment develops in the operable unit
media during the remediation period, additional remedial  action may be necessary.

8.4 Reduction of Toxicity, Mobility, or Volume Through Treatment
Variable reductions in  the toxiciry, mobility, and  volume of operable unit  media
would be achieved by implementing SSW Alternatives 5 or 6. The  selected remedy
does not involve any treatment methods to reduce the toxicity, mobility, or volume
associated with the chemicals of concern detected in Soldier  Creek sediment and
surface water. Implementation  of the no action alternative would not reduce the
toxicity, mobility, or volume of operable unit media by treatment methods. However,
because an immediate  risk  to human  health or the environment  is not posed  by
existing contaminant concentrations in the sediment or surface water, treatment of
these media to meet the cleanup goals is not warranted.

8.5 Short-Term Effectiveness
No short-term risks would  be associated with the no action alternative.  SSW
Alternative 2 will provide short-term effectiveness because there are currently no
unacceptable risks associated with Soldier Creek sediment and surface water. The
short-term risks associated with the selected remedy include exposure of the sampling
team  to operable unit media and the temporary disturbance of the Soldier Creek
ecosystem during sampling.  These impacts will be minimal because no immediate
risk exists for the sediment and surface water and  the proper sampling procedures
will be followed.   No  impacts would be encountered by off-base  residents living
adjacent  to the creek during implementation of SSW Alternative 2. The potential
risks to the site workers, off-base residents, and the environment from implementing
alternatives involving intrusive remediation activities (SSW Alternatives 3, 4, 5, and
6) would be greater than those for the preferred alternative. Cap construction and
sediment excavation would alter the physical condition and the vegetation and wildlife
in and along Soldier Creek.  Site workers and off-base residents would  be exposed
to fugitive dust emissions and surface runoff may  occur during implementation.
These  potential  exposures would be minimized  by compliance with  OSHA
requirements, by  requiring workers to wear  the appropriate personal protective
equipment, and by implementing engineering controls such as using dust suppressants,
constructing berms, and conducting air monitoring  during remediation.
Tinker AFB - Soldier Creek
Record of Decision                   8-3

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In conjunction with the FS report, an Environmental Assessment report addressing
the effects of the proposed  alternatives on human health and the environment was
prepared.  This  report  concluded that  the  impact to  the  environment  from
implementing an intrusive alternative at the operable unit would be great compared
with the limited action alternative. The construction and excavation activities that are
a part of these alternatives would severely damage or destroy the Soldier Creek
ecosystem during  implementation.  Areas downstream of the Base may also be
temporarily affected by alternative implementation. Remedial activities may alter the
creek ecosystem in a  manner  that would not allow certain species to survive.
However, over time, the ecosystem of the creek would eventually return. Through
proper engineering controls, implementation of an intrusive remedial action would
not have an  adverse  effect  on  the public  or operable  unit  workers.    The
Environmental Assessment  report summarizes the effects of each of the proposed
alternatives in greater detail.

The alternatives involving intrusive activities would take approximately one year to
construct. SSW Alternatives 2, 3, 4, 5, and 6 would involve monitoring activities to
be implemented over a five-year period. After five years, a statutory review would
be conducted to determine  the success of the alternatives.

8.6  Implementability
The no action alternative would be the simplest alternative to implement because it
only involves the completion of a five-year review at the operable unit. The selected
remedy is implementable using conventional  methods  that are established  and
reliable. The specialists, equipment, and services required to implement the selected
alternative are readily available. The alternative is much simpler to implement than
SSW  Alternatives 3,  4, 5,  and  6 because  of the  activities  involved during
implementation.   Even though  the majority of the  techniques to be used in the
intrusive alternatives are conventional and readily available, these alternatives would
involve a great deal more coordination and would be labor-intensive to implement.

8.7 Cost
The present worth cost of the no action alternative is approximately $12,000.  The
present worth cost of the selected remedy has the second lowest cost (approximately
$535,000) of all of the proposed alternatives. The approximate present worth costs
of SSW Alternatives 3,4, 5, and 6 are $2.2 million,  $2.7 million, $5.9 million, and $6.6
million, respectively.
Tinker AFB - Soldier Creek
Record of Decision                  8-4

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8.8  State Acceptance
The OSDH concurs with the selected remedy for the sediment and surface water
media at the Soldier Creek Sediment and Surface Water Operable Unit. Acceptance
of the limited action remedy, in letter form, when received from OSDH will be
included in the ROD as Appendix B.

8.9  Community Acceptance
Community acceptance is specifically addressed in the Responsiveness Summary
which is  presented in  Appendix A.  The Responsiveness Summary  provides a
thorough review of the public comments on the RI/FS, baseline risk assessment, and
Proposed Plan, and Tinker AFB's responses to the comments.  The individuals who
made verbal comments at the public meeting did not express strong support for the
selected remedy; however, no written comments were received during the public
comment period.
Tinker AFB - Soldier Creek
Record of Decision                 8-5

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                       9.0  SELECTED REMEDY

 Based on the quantitative and qualitative results of the baseline risk assessment, it
 has been determined that the sediment  and  surface water contamination at  the
 Soldier Creek Sediment and Surface Water  Operable Unit does not  present a
 significant threat to  human  health  or the  environment and,  therefore, the only
 response actions at this  time are those specified in  SSW Alternative 2, the limited
 action alternative.  Soldier Creek sediment and surface water do not pose a risk to
 human health and the environment  based on the baseline risk assessment and  the
 qualitative environmental  assessment conducted as a  part of the baseline risk
 assessment, and because remedial action objectives are met without implementing an
 intrusive response action at the operable unit. The remedial action objectives for the
 operable unit are as follows:
    •    Prevent the ingestion of or direct contact with Soldier Creek sediment and
        surface water  with  contaminant concentrations  greater  than  the final
        remediation goals.
    •    Prevent the migration of contaminants, with  concentrations greater than  the
        final remediation goals, to the groundwater that would result in groundwater
        contamination.  However, existing or potential groundwater contamination
        will be addressed under the Soldier  Creek Groundwater Operable Unit.

 Contaminant concentrations in these media do not exceed the remediation goals  for
 the operable unit.  These goals are based on the risk calculations conducted as part
 of the baseline risk assessment and are presented in Table 6-3 (pages 6-11 and 6-12).
 The investigative activities of the monitoring program and the ecological investigation
 will be used to determine if a risk to human health develops and to quantitatively
 evaluate the environmental  risk, if any,  that  exists at the operable unit.  The
 environmental assessment conducted as a part of the baseline risk assessment was
 only qualitative in nature and cannot be used to fully determine the ecological risk.

 The selected remedy consists of implementing a five-year environmental monitoring
 program of Soldier Creek sediment and surface water. Sediment and surface water
 samples will be collected along East and West Soldier Creeks. The final selection of
 these  sampling locations will  be  agreed upon by Tinker AFB, OSDH,  and EPA
 during remedial design.

 Sampling will be conducted on  a  quarterly basis  during  the first two years  of
 monitoring and semiannually during the last three years of monitoring. The sediment
 and surface water samples will be analyzed for contaminants of concern.  Volumetric
 stream flow  and the pH, conductivity, and dissolved oxygen content of the surface
 water will be measured in the  field at the time of the surface water sample collection.
Tinker AFB - Soldier Creek
Record of Decision                   9-1

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A workplan for the monitoring program will be developed during remedial design.
The workplan will be approved by all parties of the FFA, and will be the final
authority for tasks to be completed under the selected remedy. The workplan will
accomplish the following tasks, at a minimum:
    •   Establish sampling boundaries along East and West Soldier Creeks.
    •   Divide the stream into sampling segments based on visual inspection, stream
        morphology, flow characteristics, and stream use.
    •   Determine  sampling locations by dividing  each sampling  segment into
        quarters. During each quarterly sampling event, a different quarter of each
        sampling segment will be sampled.  This procedure will allow the samples
        collected over a year of monitoring to be more representative of the stream.
    •   Determine contaminants of concern.
    •   Determine and describe sediment and surface water sampling methods.
    •   Determine and describe the extent of data analysis to be conducted.
    •   Define  response if  a  sample  concentration  exceeds an  unacceptable
        exposure.  This will likely involve resampling, identifying  the  source  if
        possible, and taking the appropriate remedial action if necessary.
    •   Provide  for modifications to the monitoring program, such as expanding the
        sampling regime and boundaries if necessary.

The workplan will include all of the tasks to  be performed under the monitoring
program and during the ecological investigation.

The ecological investigation of Soldier Creek sediment and surface water conducted
as a part of the  environmental monitoring program will be used to determine the
effects of existing contaminant concentrations on the biological environment of the
creek.  An ecological assessment of the aquatic plants, aquatic invertebrates, and fish
that inhabit Soldier Creek will be  performed.   The  assessment  will  include  a
biological survey  of both on-base and off-base portions of Soldier Creek to determine
the number, identity, and approximate population size of the species living within the
Soldier Creek Sediment and Surface Water Operable Unit area. Aquatic plants will
be identified in the field, fish will be sampled with a seine and identified in the field,
and benthic samples will be collected and analyzed in a laboratory to identify aquatic
invertebrates.  The investigation will include all living organisms other than humans
and domesticated animals that may come into contact with Soldier Creek sediment
or surface water. The assessment will also be quantitative and include an exposure
assessment to identify potential contaminant pathways, a toxicity  assessment  to
identify contaminants of concern to aquatic organisms, and a risk characterization to
quantify the overall potential or actual effects of the contaminants on the plants and
animals that inhabit Soldier Creek.  The ecological assessment will also address any
existing or potential risk to the environment from PCBs.
Tinker AFB - Soldier Creek
Record of Decision                  9-2

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 Information from the Building 3001 groundwater monitoring program at Tinker AFB
 and from the investigation of the Soldier Creek Groundwater Operable Unit will be
 reviewed yearly to monitor the condition of the groundwater and to note potential
 interrelationships between sediment, surface water, and groundwater constituents.
 A yearly monitoring report will be completed to summarize the sediment, surface
 water, and groundwater analytical results and to compare the results with previously
 obtained data.  The yearly monitoring reports will be placed in the Soldier Creek
 Administrative  Record.  The monitoring  report will also be  added to the new
 Groundwater Operable Unit Administrative Record.

 During the five-year review, the results of the annual reports and other information,
 including operable unit conditions, will be evaluated. If, upon completion of the five-
 year review, the Air Force, EPA, and OSDH determine  that the Soldier Creek
 Sediment and Surface Water Operable Unit does not present a potential threat to
 human health or the environment, the sediment and surface water monitoring will be
 terminated. Statutorily required  five-year reviews will be conducted to ensure that
 no unacceptable exposures occur as specified in the NCP.

 As a part of the annual monitoring report, the quarterly and semiannual monitoring
 results will be evaluated and compared with existing data and applied to criteria to
 determine if any unacceptable exposures occur. The following criteria will be used
 to designate an unacceptable exposure:
    •   Contaminant concentrations in sediment or surface water exceeding health
        based levels based on an excess lifetime cancer risk of 1E-04.  Contaminant
        concentrations detected within the  1E-04 to 1E-06 range  may potentially
        indicate an unacceptable exposure and will be evaluated to determine if the
        exposure was unacceptable and remediation, therefore, necessary.

    •   Contaminant   concentrations  in   sediment  or  surface  water  with
        noncarcinogenic His greater than 1.0.

    •   Contaminant concentrations in sediment or surface water that  present an
        unacceptable ecological risk.

 If contaminant concentrations increase to levels where there exists an unacceptable
 exposure, then another  alternative  for remediation will be  evaluated and,  if
 appropriate, will be implemented upon consensus by the EPA, OSDH, and Tinker
 AFB.  If another  treatment alternative  is  necessary,  either an  explanation  of
 significant difference or an amendment to  the ROD pursuant to the NCP will be
 issued.
Tinker AFB - Soldier Creek
Record of Decision                   9.3

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The detailed summary of the operation and maintenance (O&M) costs associated
with the implementation of the selected remedy is presented in Table 9-1 (page 9-5).
There are no  capital costs  associated with this  alternative.   The  O&M  costs
associated with implementing this alternative consist of the sampling and analysis of
Soldier Creek sediment and surface water, an ecological assessment, disposal of
sampling-derived waste, review of the Base-wide groundwater results for wells in the
vicinity of the stream, preparation of an annual monitoring report, and  the five-year
review. The cost of the five-year review does not involve a site visit. The annual cost
for years 1 and 2 is estimated to be $175,800. The annual cost for years 3 through
5 is estimated to be $84,100.  The total present worth of the selected remedy is
estimated to  be $534,800.
Tinker AFB - Soldier Creek
Record of Decision                   9.4

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                                       TABLE 9-1
                      SELECTED REMEDY COST ESTIMATE
                             TINKER AFB - SOLDIER CREEK
                                  RECORD OF DECISION
ALTERNATIVE
COMPONENTS QUANTITY UN
IT UNIT COST COST(l)
Environmental Sample Collection (2)
Year 1-2 4 EVENT 22.000 $88.000
Year 3-5 2 EVENT 22.000 $44,000
Surface Water Analysis (3)
Year 1-2 72 SAMPLE 395 $28,400
Year 3-5 36 SAMPLE 395 $14500
Sediment Analysis (3)
Year 1-2 72 SAMPLE 375 $27,000
Year3-5 36 SAMPLE 375 $13,500
Ecological Assessment (4) 1 EVENT 20,000 $20,000
Environmental Monitoring
Program Report
Year 1-5 1 DELIVERABLE 10,000 $10,000
Five- Year Review (5)
Year 1-5 at 5 Percent

Discount Rate 1 EACH 13,000 $2.400
CAPITAL COST
O&M COST SUMMARY
Year 1-2
Year 3-5
TOTAL PRESENT WORTH
Assuming a 5 Percent Discount Rate for 5 Years
$0

$175,800
$84.100

$534300
(1) All costs rounded to the nearest hundred.
(2) Sample collection is assumed to require 3 people over a period of 7 days. Sampling-derived waste would be
   disposed of at a nonhazardous waste landfill.
(3) Analyses consist of contaminants of concern.
(4) Ecological assessment is assumed to require 2 people over a period of 6 days for the biological field survey
   and 1 person over a period of 2 weeks to prepare an exposure assessment, a toxiciry assessment, and a risk
   characterization.
(5) The future cost of the review is converted to an annual cost. A site visit would not be required as part of
   the five-year review.
                                            9-5

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                10.0  STATUTORY DETERMINATIONS


Tinker AFB's primary  responsibility at the Soldier Creek Sediment and Surface
Water Operable Unit is to undertake a remedial action that achieves adequate
protection of human health and the environment.  In addition, the selected remedy
must satisfy the statutory requirements of Section 121(b) of CERCLA.  This section
states that the selected  remedy must accomplish the following:
    •    Be protective of human health and the environment.
    •    Comply with federal and state ARARs upon completion of alternative or
        attain a waiver.
    •    Be cost-effective.
    •    Utilize permanent solutions and alternative treatment or resource recovery
        technologies to the maximum  extent practicable and  satisfy the statutory
        preference for treatment as a principle element, or justify not meeting the
        preference.

10.1   Protection of Human Health and Environment
The selected remedy is protective of human health and the environment because
monitoring of the  concentrations  of the chemicals of concern in Soldier Creek
sediment and surface water will be conducted and an ecological investigation will be
performed.  Continued monitoring will determine if a human health risk develops
from these media at the operable unit. Implementation of the selected remedy does
not pose any unacceptable short-term risks or cross-media impacts.

Because carcinogenic risk levels are within the acceptable risk range (1E-04 to 1E-06)
and the His for noncarcinogens are less than 1.0, the sediment and surface water
contamination at the Soldier Creek Sediment and Surface Water Operable Unit does
not present  a significant  threat to human health.   Based on  the  qualitative
environmental assessment conducted as a part of the  baseline risk assessment, a
significant threat to the environment does not exist. Therefore, the only response
action required at this time is that specified  in the selected remedy. The continued
monitoring of Soldier Creek sediment  and  surface water at on-base and off-base
sampling locations will be adequate to address operable unit contamination because
the concentrations  of the sediment and surface water COCs do not exceed the
remediation goals (risk-based cleanup levels) established for the operable unit. The
ecological assessment to be conducted will determine the effects of contaminant
concentrations on the biological environment of Soldier Creek.  Yearly and at the
time of the five-year review, the results of the monitoring program will be evaluated
to determine if a remedial action needs to be implemented or additional monitoring
needs to be conducted at the operable unit.
Tinker AFB - Soldier Creek
Record of Decision                  10-1

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10.2 Compliance with ARARs
The selected remedy complies with the federal and state action-specific ARARs for
the operable unit. These ARARs include the following:
   •   RCRA.
           Hazardous Waste Management Systems General (Part 260).
           Identification and Listing of Hazardous Waste (Part 261).
           Standards Applicable to the Generators of Hazardous Waste (Part 262).
           Standards Applicable to Transporters of Hazardous Waste (Part 263).
           Standards Applicable to  Owners and Operators of Hazardous Waste
         .  Treatment, Storage, and Disposal Facilities (Part 264).
           Land Disposal Restrictions (Part 268).
       -   Hazardous Waste Permit Program (Part 270).
   •   Hazardous Materials Transportation Act.
   •   Oklahoma Controlled Industrial Waste Disposal Act.
   •   Oklahoma Pollution Control Coordinating Act of 1968.
   •   OSHA.

The contaminant-specific ARARs for the operable unit include the following:
   •   Risk-based Cleanup Levels.
   •   RCRA-Identification and Listing of Hazardous Waste (Part 261).
   •   Oklahoma WQS.
   •   AWQC.

Several surface water constituents exceeded the Oklahoma  WQS and the  AWQC
during Phases I and II of the RI. However, sediment  and surface water monitoring
will be adequate to determine if an unacceptable risk  develops at the operable unit
and if the surface water constituents continue to exceed the Oklahoma WQS and the
AWQC.  There are currently no location-specific ARARs  for the Soldier Creek
Sediment and Surface  Water  Operable Unit; however, these ARARs  will be
reevaluated throughout the remedial process and the  status changed if necessary.

10.3 Cost-Effectiveness
The selected remedy is  cost effective because it has been determined  to  provide
overall effectiveness proportional to its cost. The net present value of the remedy
is approximately $535,000.  Because the baseline risk assessment determined that the
Soldier Creek Sediment and Surface Water Operable Unit in its current condition
does  not pose a significant threat to human health and the environment, an intrusive
response action is not necessary at this time. Therefore, the selected remedy is the
least  costly of remedies that are sufficiently protective of human health and the
environment.
Tinker AFB - Soldier Creek
Record of Decision                  10-2

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 10.4 Utilization of Permanent Solutions and Alternative Treatments
 The selected remedy utilizes permanent solutions and treatment technologies to the
 maximum extent practicable.   However, based on the results of the baseline risk
 assessment, meeting this criterion does not currently require the involvement of
 permanent treatment solutions.  Because remediation is not necessary at the Soldier
 Creek Sediment and Surface Water Operable Unit, the selected remedy offers long-
 term effectiveness and permanence in the protection of human health  and the
 environment.   Although no  reduction  of toxicity,  mobility, or  volume  of  site
 contaminants through  treatment will occur as a result of implementing the selected
 remedy, the proposed monitoring program will provide short-term effectiveness. The
 potential short-term risks to site workers,  the community, and  the Soldier Creek
 ecosystem during implementation are minimal compared to the risks associated with
 an intrusive remedy. The selected remedy is easily implementable, and the cost is
 low compared to the costs of implementing an intrusive remedy.

 If, over the five-year period before the statutory review, monitoring indicates  an
 increase in contaminant concentrations to the point where the sediment or surface
 water consistently exceeds the risk-based cleanup levels, implementation of another
 site remedy will be evaluated.  If one of the other treatment alternatives is necessary
 at the operable unit, either an explanation of significant differences or an amendment
 to the ROD pursuant to the NCP will be issued.

 10.5  Preference for Treatment
 CERCLA provides  a  statutory  preference for remedies  that use treatment as a
 principle element of a  remedy. However, as it  has been determined that treatment
 is not necessary, it will not be used at this operable unit. Treatment of Soldier Creek
 sediment and  surface  water is not practicable because the concentrations of site
 contaminants of concern do not exceed the acceptable range of carcinogenic risk
 values and noncarcinogenic HI values developed in the baseline risk assessment.
 Because the values are not exceeded, there is no basis on which to calculate areas to
 be remediated.
Tinker AFB - Soldier Creek
Record of Decision                  10-3

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       11.0  DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for the Soldier Creek Operable  Unit was released for public
comment on April 15, 1993. The public comment period ended on June 17, 1993.
It identified  the preferred alternative to be the  limited action alternative, which
involves continued monitoring of Soldier Creek sediment and surface water and an
ecological assessment to be conducted at the operable unit. No significant changes
will be made to the proposed remedy as a result of the public comment period.

Tinker AFB-Soldier Creek
Record of Decision                 11-1

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      APPENDIX A



RESPONSIVENESS SUMMARY

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A.1  INTRODUCTION
The purpose of this responsiveness summary is to present the significant comments
received during the public comment period on the RI/FS and the Proposed Plan and
to respond to those comments and how they affected the ROD.

The Proposed Plan and the Administrative Record file were made available to the
public in April 1993 in the Midwest City Public Library, Tinker AFB, the OSDH (as
of July 1, 1993,  this  division of OSDH became part of the new Department of
Environmental Quality) offices in Tulsa, Oklahoma, and the EPA Region 6 offices
in Dallas, Texas.  The public comment period was scheduled to be open between
April 16,1993 and May 17,1993. A public meeting was scheduled and held on April
27, 1993. Both the public comment period and the public meeting were initially
announced to the public in the Daify Oklahoman, which is a large local newspaper
of general circulation, on April 16, 1993.  Another newspaper announcement was
placed in the community section of the Daify Oklahoman on April 26,1993. A press
conference was also held the same day to announce  the public meeting.  At the
public meeting, a request was received to extend  the public  comment period.
Accordingly, the public comment period was extended to  June 17, 1993.  A notice
was placed  in the Daify Oklahoma for three  days  notifying  the public  of this
extension.

A.2  SOURCE OF COMMENTS
Public comments were received verbally during the public meeting.  No written
comments were received during the public comment period.

A copy of the transcript of the public meeting  is available in the Administrative
Record file.  The  content of the verbal comments and  Tinker AFB's comments are
contained in this summary.

A.3  SUMMARY OF COMMENTS FROM  THE PUBLIC  HEARING
AND TINKER AFB'S RESPONSE
The following is a summary of the comments  received during the public meeting.
After each comment is a summary of the Tinker AFB response provided at the
meeting. The comments and responses are presented in the order that they were
addressed during the public meeting.

Commentator 1
1. Comment:
   Is Tinker AFB aware of the Good Neighbor Agreement made between Tinker
   AFB and the Citizens for a Clean Environment  a few years back? A free
   exchange of information and data to the group is to be provided upon request,
   as long as the information is not  classified.  Approximately one  year ago, I
   requested the field study of risk assessment data and I was refused on the
                                 A-l

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    grounds that it was raw data and it had not been compiled and extrapolated.  I
    feel that this is potentially a violation of the Good Neighbor Agreement.

    Tinker AFB's Response:
    Tinker AFB is aware of the Good Neighbor Agreement between the Base and
    the Citizens for a Clean Environment. To Tinker AFB's knowledge, everything
    asked for by the group has been provided, from community awareness to the
    chemicals on the Base. We have given your organization tours of the Base. At
    the time of the request for the raw data, nothing was available to give the group.
    This data is now available in the Administrative Record file, which is available
    at the Midwest City Public Library.

2.   Comment:
    Why did the group not receive notice of the public comment period before April
    16, 1993?  Tinker AFB may have fulfilled their legal obligation by placing the
    notice in  the back of the Journal Record, but if Tinker AFB knew that there
    was an interested group that represented a great number of people, why was the
    group not notified earlier? I had made earlier inquiries before as to when this
    information would be made available but I was never given notice that it is now
    available to the public. Tinker AFB knows of the group's existence and has our
    mailing address and phone number.

    Tinker AFB's Response:
    Tinker AFB had no intention of slighting any citizen or group on the availability
    of the Administrative Record file and the notice of the public comment period
    and meeting.  The public notice was placed in the Daily Oklahoman; however,
    Tinker AFB has no control over where in the newspaper the notice is placed.
    Tinker AFB apologizes that your group took offense to the fact that the notice
    was not sent to you directly. A notice was also sent out to the mailing addresses.
    At that time, 30 days were remaining in the public comment period.

3.   Comment:
    I received a notice in the mail that was postmarked April 23, 1993. I received
    it on April 24, 1993. This is quite a few days after the public comment period
    began. The citizens were slighted on the public comment period and the notice.
    It will take a while to  look over this information to either agree with it or to
    identify opposing experts.

    Tinker AFB's Response:
    The information that you received on April 24, 1993 was the Fact Sheet.
                                   A-2

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4.  Comment:
    In the  Soldier Creek investigation, was any  consideration given  to  soil,
    groundwater, or air quality contamination in other areas that will impact the
    creek or was it looked at as a single entity?

    Tinker AFB's Response:
    The remedial investigation was specifically conducted on Soldier Creek sediment
    and surface water at on-base and off-base locations.  The investigation focused
    on specific chemicals in the creek sediment and surface water to determine the
    nature and extent of contamination.  Identification of the chemicals does  not
    necessarily determine the source of the contamination. In addition to sediment
    and surface water data, the RI report summarizes groundwater data collected in
    the vicinity of Soldier Creek. A baseline risk assessment was prepared to address
    exposure to all three of these media.  However, only the sediment and surface
    water were addressed in subsequent documents (FS, Proposed Plan, and ROD)
    because the groundwater data was not adequate to fully determine the horizontal
    and vertical extent of contamination and the hydrogeology in the area of Soldier
    Creek is complex.  It was determined that the groundwater contamination could
    be more thoroughly and properly evaluated by conducting additional investigation
    and by establishing a Soldier Creek groundwater operable unit at the Tinker
    AFB  Site.   All  of the   aforementioned documents are available  in   the
    Administrative Record file.

5.  Comment:
    Was there any potential for backwash of contaminants from the main portions
    of Soldier Creek  that originate on the Base into the "C" and "D" tributary
    segments of Soldier Creek used as background locations?

    Tinker AFB's Response:
    The background locations were selected far enough downstream of Tinker AFB
    and at distance from the confluence of the tributaries with the main portion of
    Soldier Creek to avoid a "backwashing" of contaminants from Tinker AFB into
    these tributaries.  In addition, the background locations were placed on private
    property so as to avoid potential sources of off-base contamination.

6.  Comment:
    Were  any contaminants found in the area of segment M3?

    Tinker AFB's Response:
    Bis(2-ethylhexyl)phthalate (3 out of 4 samples) and barium (4 out of 4 samples)
    were detected in the 0-6 inch sediment sampling interval (Phase I of the RI).
    Chlorobenzene (one out of 8 samples),  bis(2-ethylhexyl)phthalate  (7 out of 8
    samples), and barium (8 out of 8 samples) were detected in the 0-5 foot sediment
    sampling interval (Phase II of the RI).  Chloroform (2 out of 4 samples); cyanide


                                    A-3

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    (one out of 4 samples); and chromium, potassium, selenium, and sodium (4 out
    of 4 samples) were detected in the surface water (Phase I of the RI).

7.   Comment:
    Does Tinker AFB agree that Soldier  Creek is a recharge site  of the Garber-
    Wellington Aquifer?

    Tinker AFB's Response:
    Along the length and breadth of the stream, Soldier Creek is a recharge site.  It
    is either recharged by the groundwater or recharges the groundwater along its
    length. In the  immediate area surrounding Tinker AFB, preliminary data has
    indicated that the  groundwater recharges the creek system, but the creek does
    not recharge the groundwater. Investigations are currently being conducted to
    more fully evaluate the interactions between Soldier Creek and the  Garber-
    Wellington Aquifer. Flow measuring devices have been placed in the creek and
    the permeability of the creek sediment is being measured.

8.   Comment:
    For risk assessment exposures, did the sampling team go door to door in the
    neighborhood just south and northeast of 10th Street and interview any of the
    neighbors. Many of the children in this neighborhood play in the creek and catch
    crawfish.  There are some fish large enough in the creek for the kids  to catch
    and take home to  eat.  In addition, many metals are bioaccumulative.

    Tinker AFB's Response:
    Exposure scenarios used  in the baseline risk assessment  did  not necessarily
    consider a specific individual but a type of receptor that may be exposed to the
    creek system.  The exposure scenarios are independent of who lives along the
    creek because a risk is estimated for each individual segment.   The risks were
    evaluated for more broad-based receptors  (e.g., adult worker, child or adult
    playing in creek).  The Agency for Toxic Substances and Disease Registry is the
    agency responsible for conducting door to door interviews and other  types of
    inquiries of this nature.  Such an assessment was  conducted in May 1993.

    It is correct that many metals bioaccumulate. The effect of such metals, if any,
    on  the Soldier Creek ecosystem will be  fully evaluated during the ecological
    investigation to be conducted as a part of the selected remedy.

9.   Comment:
    It was stated that some of the chemicals in one of the surface water grab samples
    exceeded the water standard.  Were any of these samples collected during a
    period when Tinker AFB was in violation of its NPDES permit?
                                    A-4

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    Tinker AFB's Response:
    Phase I and II of the RI samples were not collected during a period of NPDES
    permit violation.  However, on June  18, 1990, the discharges  from the Base
    exceeded permit requirements for pH.  On June 7,1991, the discharges from the
    Base exceeded permit requirements for total suspended solids.  Both of these
    permit violations occurred before the sediment and surface water was sampled.

10.  Comment:
    Water quality varies from day to day in Soldier Creek depending upon what is
    discharged from the Base. If a sample was taken on a day of minimal discharges
    as opposed to a day of discharges that resulted in permit violations, it  would
    make a considerable difference in  the concentrations of the sample collected,
    especially in making any kind of health risk assessment.

    Tinker AFB's Response:
    That is correct. For this reason, surface water samples were collected during two
    sampling  events, Phase I (July 1990) and  Phase II (June 1991) of the remedial
    investigation.
Commentator 2
11.  Comment:
    I would like to begin by going on the record asking for an extension of the public
    comment period. There has not been enough time allowed for anyone to study
    the situation adequately.  I just received the notice yesterday, so  I need more
    time to respond.

    Tinker AFB's Response:
    The public comment period has been extended until June 17, 1993.

12.  Comment:
    In regards to the recharge of the creek, I have done hydrogeological studies that
    show that the shallow aquifer of the alluvium recharges Soldier Creek and that
    Soldier Creek  recharges  the  Garber-Wellington Aquifer.  Therefore, I  am
    concerned about this charge and recharge of the stream.  It is known that the
    alluvium is contaminated with  trichloroethene and chromium; therefore, it  can
    be expected that these contaminants will enter the surface water and ultimately
    seep down.   My concern is that during this particular study, the focus was on
    sediment and surface water.   I assume that the reason you focused on these
    media was because it is the first pathway to human exposure.  However,  the
    selected remedy of a five-year study including groundwater and ecological studies,
    should already have been occurring before it got to this point. My concern is,
    with the recharge issue, it appears that you are chasing your tail in making a
    decision before going further into remediating the site.


                                    A-5

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    Tinker AFB's Response:
    In  the answer to  the previous question  concerning recharge, it was not the
    intention to give  an indication of where  Tinker AFB is at in the overall
    investigation and study process at the Base, but to answer a direct question about
    recharge in the area of Soldier Creek.

    Under CERCLA,  as amended by SARA, there is a set procedure to follow in
    performing remedial investigations and  feasibility studies.   Tinker AFB  is
    required by the EPA to follow these procedures.  Perhaps  things could be
    conducted to expedite the process, but the process that Tinker AFB executed to
    get to this point was explained during the public meeting presentation.

    The groundwater associated with Soldier Creek is not going to be addressed in
    the five-year program of the selected remedy because not enough data exists to
    determine the horizontal and vertical extent of groundwater contamination and
    the hydrogeology in the area of Soldier Creek is complex.  The groundwater will
    be addressed as a separate operable unit entitled the Soldier Creek Groundwater
    Operable Unit.  The objective of the flow measuring devices installed in Soldier
    Creek was not to support the existing study (Soldier Creek Sediment and Surface
    Water Operable Unit), but to get a head start on the groundwater operable unit
    investigation.

13.  Comment:
    When can we expect results on the groundwater?

    Tinker AFB's Response:
    Tinker AFB actively monitors groundwater monitoring wells in the area of
    Soldier Creek as a part of the basewide groundwater monitoring program.  In
    addition, Tinker AFB will  be going through the same type  of process in
    addressing the groundwater as it did to address the sediment and surface water.
    We will be developing  a workplan and a sampling and analysis plan before
    beginning the actual investigation. These activities will begin within the next
    couple of months,  as soon as a complete schedule is set.

14.  Comment:
    Was bioremediation considered as part of the plan?

    Tinker AFB's Response:
    Bioremediation was considered during the initial technology screening process
    conducted during the feasibility study and as presented in the FS Initial Screening
    of Alternatives Report.
                                    A-6

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15. Comment:
    Why was bioremediation not included in this plan?

    Tinker AFB's Response:
    Bioremediation was not included for several reasons.  First of all, both organic
    contaminants and  metals are present in the sediment  and  surface water.
    Bioremediation is appropriate only for remediating organic contaminants that are
    biodegradable.  In  addition, some metals, such as  chromium and cyanide, are
    toxic to the biological treatment process.  Chlorinated organic  compounds can
    also  be toxic to the process at high  concentrations.   To  effectively  sustain
    biological treatment, a relatively high concentration of organic contamination
    must be  present in the medium to be remediated.  Biodegradable organic
    contaminants are present at low concentrations in Soldier  Creek sediment and
    surface water.

16. Comment:
    I  would like  to be on the record for asking  that SSW  Alternative 4 using
    bioremediation to  protect public health and the environment  in the area of
    Soldier Creek be implemented at the site. I would like Tinker AFB, OSDH, and
    the City of Midwest City to put up health warning signs along the creek warning
    children not to play there, not to eat the fish, and not to play with  the aquatic
    life, in order to protect the health and safety of the residents of Midwest City.

    Tinker AFB's Response:
    The baseline risk assessment conducted for Soldier Creek sediment and surface
    water indicates that no unacceptable risk exists. Because the concentrations of
    contaminants in the sediment and surface water do not exceed values determined
    in  the baseline risk assessment  to be a  threat  to  human  health or  the
    environment, it is impossible to determine the areas or volumes of media that
    would be remediated. Existing data does not indicate that  a remedy should be
    selected.  An ecological investigation and assessment will be conducted as a part
    of the selected remedy to more fully define the risk to the  environment.

    As stated in the response to the previous question, if remediation were necessary
    for Soldier Creek sediment or surface water, bioremediation would not be an
    appropriate treatment technology to select.

17. Comment:
    I understand that is Tinker AFB's position.  However, these  chemicals were
    found in the surface water and sediment in the areas where children play. I am
    saying this without the benefit of looking at the values put in the risk assessment
    formula.  I feel there is a concern with  direct exposure.
                                    A-7

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    Tinker AFB's Comment:
    The assumptions and exposure scenarios used in the baseline risk assessment         (
    were conservative and the assessment was conducted following approved EPA
    guidelines. The baseline risk assessment concluded that an unacceptable risk to
    children, adults, and adult workers does not exist from Soldier Creek sediment
    and surface water. An ecological investigation and assessment will be conducted
    as a part of the selected remedy to more fully define the risk to the environment.

Commentator 1
18.  Comment:
    I would like to make a comment about the fact that there is no risk. Earlier I
    asked if sampling was conducted during periods of NPDES permit violation. If
    samples were collected on a day when there were no contaminants discharged
    to the creek, there would be no risk.  But on a day a child might be playing in
    the creek and a permit violation is occurring, a health risk would certainly exist
    on that day.

    Tinker AFB's Response:
    Discharge from the  IWTP,  and  any  risks  associated  with  releases  of
    contaminants, is covered under Tinker AFB's NPDES permit.  The sampling
    conducted as a part of the remedial investigation was to define the extent of
    sediment and surface water contamination in Soldier Creek.  The releases that
    you are referring to  are incidental and infrequent occurrences, and  are  not
    considered exposures when conducting a risk assessment. The releases represent
    an incidental exposure that does not represent an overall, long-term risk from
    Soldier Creek sediment and surface water. The long-term risk to human health
    and the environment is represented by the contaminants that are present in the
    sediment and provide a source of contaminants that feed the surface water. This
    type  of risk, if it existed, would have been determined by the baseline risk
    assessment.

Commentator 3
19.  Comment:
    My family lives across  from Building 3001.  Nothing has been said of  the
    chemicals that are absorbed through  the  skin  during showering.   We  drink
    bottled water, but we are still taking showers.

    Tinker AFB's Response:
    We understand your concern. This investigation addresses sediment and surface
    water contamination associated with Soldier Creek. Groundwater contamination
    in the area of Building 3001 is currently being addressed through remediation.
    The groundwater in the area of Soldier Creek will be further investigated under
    the Soldier Creek Groundwater Operable Unit.
                                   A-8

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20. My children also play in Soldier Creek.  How do you determine the effects of
    contaminants on skin?

    Tinker AFB's Response:
    During the baseline risk assessment, exposures scenarios were  evaluated for
    dermal, or skin, contact from Soldier Creek sediment and surface water. Studies
    are conducted to determine the absorption rate of contaminants for both children
    and adults. The absorption rate data used in the baseline risk assessment was
    obtained from established and EPA-approved data bases.

Commentator 4
21. Comment:
    My primary concern is how long Landfill 6 has been in use.  Were there any
    chemicals or industrial waste from that landfill detected in the samples collected
    during the RI.

    Tinker AFB's Response:
    There were sampling locations along the length of Soldier Creek  in the area of
    Landfill 6. If contaminants were coming from Landfill 6 they would have been
    detected during the investigation. However, the focus of the RI was the sediment
    and surface water in Soldier Creek, not Landfill 6.

22. Comment:
    Does Landfill 6  have a sufficient containment system for early detection?

    Tinker AFB's Response:
    A cap was constructed on Landfill 6.  The cap was  built according to RCRA
    standards when  designed and constructed.  Landfill 6 is also surrounded  by a
    monitoring well  system that will enable detection of contaminant  migration.
                                   A-9

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        APPENDIX B



STATE LETTER OF ACCEPTANCE

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09/09/93   16:24
  MASK S. COUGMAN
  Executive Director
                                          OC-ALC/EM
                                                         -»-»-» EPA.CERCLE BRANC  12 001/001
                                                            DAVID WALTERS
                                                            Governor
                                 State of Oklahoma
                 DEPARTMENT OF ENVIRONMENTAL QUALITY
                                         Post-
                                              -It" h'°"^ fa* transmittal memo 767t |ffo«P»9«« »  f_
  September 2, 1993
  Joe D. Winkle
  Regional Administrator, Acting
  EPA Region VI
  1445 Ross Ave.
  Dallas, TX 75202
                                                              ..'«.' :"-;iV  ^iitSifc- '"'•''- """'' •''
                                                                   -.' -',;-'-• -"St'i'-.-'-i^.''-''^ ' '
                                                                 •".u' . -^-'' ^Jr^Hv; ' ." -  ••,
  Subject:     Soldier Creek Sediment and Surface Water Record of Decision

  Dear Mr. Winkle:
                                         - :•   •       ••  .•-.
  The Department of Environmental Quality (DEQ) has revjewedlw
  Surface Water Administrative Record and expressly, :
  Decision.  The baseline risk assessment estabttsjies ^^
  water do not pose a significant risk to human h6all
  concurs with the selection of the limited action' remedy as
  Creek sediment and surface water contamination.        *
                                                     • '* -i- '.  
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