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
-------
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)
-------
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
-------
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.
-------
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
-------
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
-------
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
-------
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 4Sediment Excavation and Off-Base Landfill
Disposal 7-5
Tinker AFB - Soldier Creek
Record of Decision TOC-2
-------
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
-------
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
-------
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
-------
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
-------
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
-------
ug/L Microgram per liter
ug/kg Microgram per kilogram
WQS Water Quality Standards
Tinker AFB - Soldier Creek
Record of Decision ii
-------
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
-------
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
-------
,=,
ii on g x i i
n i- s a i §
rii i
I s i\ 3 V--8 ; ii "
iiiiilmiiiiiiiimiEJiiimmimiiiiiiic.liuiiiiiiiiiiiiiiiiiit.i iimmiiimiimiiEniiiMm miMmmiiiimgiiiiNiiiiiiiiiiiiiuiimimiimi
JIN
S'""i!
= 55
iiiiiiiuiiiiiiiiiiiiiiii!iiiiiiii{iiiiiniiiiiiiiiii»iniiiiiiiiiiiiiiiiiiiiiiin>iii>iiiiiiiiiiiiii§iiiiiirauiinii«iuiiii
^11
\l /
M/
s
Ul
m
a:
ct
UJ
a.
a
UJ
ui
a:
u
o o
Z_i »-
._ o tn
O co .-.
(\J
I U
Q
u. u.
et O
i iimiiiiiiiiiatHiiiiiiiiiiiniiHtwiiuiMiHtiiiiiniiunniiuMiiHiHiiiinMiiiitiiiHiiiHiiuitiiiiitJiigiiiniiiiiiHiiiiiuiiiiiiiiiriHiitii
ilmiiiiiiiiiiiiiiiiioi'tiiiHiiiiiriiiiuiiiiHiiintiiuiiiiKiifiiitiiiiiHiiiiiiiiuriiiitiiiiiiiiiuiiiiiiMiiiiiiiMuii Mfiiiiiii
I /
o =
51
"1
=
i
|
2
=
~
I
>-
^
i
en
u
Q
2
/£
/*
: tf.
Je
/ A
/ *
/ ^
/ ^3
/ ^
=
=
I
i
t ^
tn =
i
=
§
1
j
*
*
i
IO)
o
i i
i-
a:
o
a.
a
a:
Lul
NX
z
£c/>
a:
U_CQ
:u z
u
uiiuniimii ....... rginnnin ...... i ...... "' ........ nil ......... aimmiii ..... iiiwimiwimini ..... IB,,. ...... iliiiin ......... i»ii|im.i CC OZ UJ
8 7
I o ao: QL.
I ICQ UO
i I Q
I (Qi ZL.
I il- DO QQ«C
UJH-
Qt-O
_
uaa.
i-3
-------
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
-------
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
-------
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
-------
iiiiimiiiHiiifiimimitimiiiiiiii
,
;
1
i
K
& \
s N
ii
11
II
=£
11
if
s I!
0 ii
> i:
H
\ i
i ==
CREEK
K
UJ
5
d
CO
d
o
I
u
tf
;:s
i
§
s
E
E
i
i
E
=
fill
^
L
?
C
L
C
c
C
lU
=
svnsnoo ' I nanoo
\ m
mm uniiiimiiiiiiMiiiitiiiiffli imiiiiiiiimmiimiiniim iiiiiiiiiiiiiinimimiiiliMiiiiiiiiiinimiM uiipii umiipiiii
= 0211 /
ii
U
Q
§
Z
= y
I 5
i 3
i L
| 3
iniiiiiiwmiiiiniiiiiiiiiiiiniliuiiiiinuuiiiiiniiiuiiiniitiiniiiiiiniiiiiiiiiiiuiiimiiinuiiiiiiirainiiiiiiiiiniiMiiniiiiimuiiiiii
>- O
^^ I ^Mrf
^^ «J ^^
-I Z t-
Z O ec
O O
z. o
Z O _l
O >-i
t- O
t- ec Z
ec 0 -i
U O _l
O _j Q.
_J S
O eC
CS Z CO
Z -
O
o
o
I'
CM
O
o
o
CM
II
liJ
i-cn
eC
O
o
o
o
CM
i
iiiiiiiiiiiiiniigui
I
i
o
Ul
>-u
eCO
QU.
_J CL
Q- S
Z ec Q
eC U) Z
O» eC
No-
| 30 ~^
i
Ul I.I 111
CO CO CO
s s ?
Q- Q. CL
5-3
-------
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
-------
00
8
CO
CO
S
2
HH
Q
W
oo
ll
W <
J >
^
0
u
u
B; ^
w «
s ^J
Q W
o£
7s
£§
< o
S 8
8
u
E
D
CO
J
0
H^
S
a
jf
TJ
g i
^o
r. 2 s
>.
o a
gB i
a £
1
5
c
uj n i
65 I
^J < 7
SS
1
85
8
SS
1
SS
88
888
11
22
ii
88
83
fc S
fep
8
88
*
Q
«
!
i
88888
6-3
-------
CO
g
s
o
to
LU
tr
D
&
ui
o
h-
<
I
BILITY
ANT
SLOPE
FACTOR
kg-day/m
ET
AN
EM
£& 5
CHEMI
OF POTE
CONC
lph
gg
SS
i i
gg
ID in
I
l
gg
g
g
6-4
-------
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
-------
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
-------
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
-------
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
-------
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 ActNational 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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
APPENDIX A
RESPONSIVENESS SUMMARY
-------
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
-------
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
-------
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
-------
(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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
APPENDIX B
STATE LETTER OF ACCEPTANCE
-------
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- '.
------- |