PB95-964603
                                EPA/ROD/R10-95/108
                                March 1995
EPA  Superfund
       Record of Decision:
       Elmendorf Air Force Base (O.U. 5),
       Greater Anchorage Borough, AK
       12/28/1994

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UNITED STATES AIR FORCE
ELMENDORF AIR FORCE BASE, ALASKA


ENVIRONMENTAL RESTORATION PROGRAM
RECORD OF DECISION
OPERABLE UNITS
FEBRUARY 1995

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                            TABLE OF CONTENTS


                                                                        Page

PART I.     DECLARATION	  1

PART II.    DECISION SUMMARY	1-1

1.0   SITE DESCRIPTION  	1-1

      1.1    Physical Description	1-1
      1.2    Land Use   	'.";'	1-4
      1.3    Hydrogeology and Groundwater Use	1-5

2.0   SITE HISTORY AND ENFORCEMENT ACTIVITIES	2-1

      2.1    Identification of Activities Leading to Current Contamination at OU 5 ... 2-1
      2.2    Regulatory and Enforcement History	2-7
      2.3    Role of Response Action	2-8
      2.4    Community Participation	2-9

3.0   SITE CONTAMINATION, RISKS, AND AREAS REQUIRING RESPONSE
      ACTIONS  	3-1

      3.1    Nature and  Extent of Contamination	-3-1
      3.2    Risk Evaluation	  3-17
      3.3    Established  Final Contaminants of Concern (COCs) and Cleanup Levels   3-24
      3.4    Summary   	  3-24

4.0   REMEDIAL ACTION OBJECTIVES, ALTERNATIVES, AND
      COMPARATIVE ANALYSIS	4-1

      4.1    Remedial Action Objectives  	4-1
      4.2    Alternatives	4-1
      4.3    Summary of Comparative Analysis of Alternatives	4-12
            4.3.1  Threshold Criteria	  4-12
            4.3.2  Primary Balancing Criteria	  4-14
            4.3.3  Modifying Criteria  	  4-16
Hlmendorf AFB OU 5 Record of Decision

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                      TABLE OF CONTENTS (Continued)

                                                                          Page

5.0   SELECTED REMEDY  	5-1

      5.1   Statutory Determinations  	5-5
            5.1.1  Protective of Human Health and the Environment  	5-5
            5.1.2  Applicable or Relevant and Appropriate Requirements (ARARs) .. 5-6
            5.1.3  Cost Effectiveness	  5-11
            5.1.4  Utilization of Permanent Solutions and Alternative Treatment
                  Technologies to the Maximum Extent Practicable	  5-11
            5.1.5  Preference for Treatment as a Principal Element  	  5-13
      5.2   Documentation of Significant Changes	  5-14

PART III.   RESPONSIVENESS SUMMARY	6-1

APPENDIX A: INDEX TO OU 5 DOCUMENTS IN ADMINISTRATIVE RECORD
Elmendorf AFB OU 5 Record of Decision                11

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                                LIST OF FIGURES






                                                                               Page




1-1   Location Map of Elmendorf AFB, Alaska	1-2




1-2   OU 5 Land Uses  	1-3




1-3   Hydrogeologic Conceptual Model  	1-6




2-1   A Schematic of Principal Transport Mechanisms in OU.5	2-2




2-2   Potential Source Areas in OU 5	2-4




2-3   General Locations of Source Areas  	2-6




3-1   Organic Contaminants Detected in Upper Aquifer Groundwater	3-7




3-2   Organic Contaminants Detected in Upper Aquifer Groundwater	3-8




3-3   Organic Constituents Detected in  Surface Water and Sediment  . .  . ;	3-10




3-4   Organic Constituents Detected in  Surface Water and Sediment	  3-11




3-5   Organic Contaminants Detected in Soil	  3-12




3-6   Organic Contaminants Detected in Soil	  3-13




3-7   Inorganic Elements Detected in Soil Above Background Levels  	  3-15




3-8   Inorganic Elements Detected in Soil Above Background Levels  	  3-16




3-9   Human Health Risk in OU 5  	  3-21




4-1   Elmendorf AFB Benzene Concentrations at the Water Table (Present)  	4-3




4-2   Elmendorf AFB TCE Concentrations at  the Water Table (Present)  	4-4




4-3   Elmendorf AFB Benzene Concentrations at the Water Table (10 Years)  	4-5




4-4   Elmendorf AFB TCE Concentrations at  the Water Table (10 Years)  	4-6




5-1   Selected  Remedy  	5-3








Elmcndnrf AFB OU 5 Record of Decision               iii

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                                 LIST OF TABLES


                                                                              Page

3-1    Potential Contaminants .of Concern — Water  	3-2

3-2    Potential Contaminants of Concern — Sediment	3-4

3-3    Potential Contaminants of Concern — Soil .	3-5

3-4    Parameters Used in the Risk Assessment	3-18

3-5    Human Health Risks	;	  3-22

3-6    Final Contaminants of Concern and Cleanup Levels  	  3-25

5-1    Chemical-Specific Applicable or Relevant and Appropriate Requirements  	5-7

5-2    Location-Specific ARARs	5-8

5-3    Action-Specific Federal ARARs	5-9

5-4    Action-Specific State ARARs and TBCs	5-10

5-5    Maximum Allowable Effluent Discharge Based on Background Concentrations
       of Metals in Groundwater	  5-12
Elmcndorf AFB Olj 5 Record of Decision                IV

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                                ACRONYM LIST
AAC
ACM
ADEC
AFB
ARARs
ASWQ
BESG
BTEX
CERCLA

CFR
COC
COE
CPF
CSF
ELCR
ERA
FFA
FS
GMR
HI
HRA
IRIS
IRP
MCC
MCL
MCLG
mg/kg  .
NCP
ND
NFA
NPDES
O&M
OU
PAH
PCB
PCE
RfD
RI
RME
ROD
SARA
Alaska Administrative Code
Alaska Cleanup Matrix for non-Underground Storage Tank soil
Alaska Department of Environmental Conservation
Air Force Base
Applicable or Relevant and Appropriate Requirements
Alaska Surface Water Quality standards
Elmendorf Bioenvironmental Engineering Services Group
Benzene, Toluene, Ethylbenzene, and Xylene
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
Code of Federal Regulations
Contaminant of Concern
Corps of Engineers
Cancer Potency Factor
Cancer Slope Factor
Excess Lifetime Cancer Risks
Environmental Risk Assessment
Federal Facilities Agreement
Feasibility Study
Groundwater Modeling Report
Hazard Index
Health Risk Assessment
Integrated Risk Information System
Installation Restoration Program
Maximum Contaminant Concentration
Maximum Contaminant Level
Maximum Contaminant Level Goal
Milligrams of Contaminant/Kilogram of Medium (soil)
National Oil and Hazardous Substances Pollution Contingency Plan
Not Detected
No Further Action
National Pollution Discharge Elimination System
Operation and Maintenance
Operable Unit
Polycyclic Aromatic Hydrocarbons
Polychlorinated biphenyl
Tetrachloroethene
Reference Dose
Remedial Investigation
Reasonable Maximum Exposure
Record of Decision
Superfund Amendments and Reauthorizauon Act
Elmcndorf AFB OU 5 Record of Decision

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                             ACRONYMS (Continued)
SERA
SQC
SVOC
TBC
TCE
TFH
TOC
TPH
/ig/L
USAF
U.S. EPA
VOC
State/Elmendorf Restoration Agreement
Sediment Quality Criteria
Semivolatile Organic Compound
To be considered; guidance or criteria not promulgated (and therefore
not an ARAR) that is nonetheless "to be considered" in developing
remediation goals
Trichloroethylene
Total Fuel Hydrocarbon
Total Organic Carbon
Total Petroleum Hydrocarbon
Micrograms of Contaminant/Kilogram of Medium (soil)
Micrograms of Contaminant/Liter of Solution (water)
United States Air Force
U.S. Environmental Protection Agency
Volatile Organic Compound
Elmendorf AFB OU 5 Record of Decision
                      VI

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                             PARTI.  DECLARATION
             SITE NAME AND LOCATION
             Elmendorf Air Force Base (AFB)
             Operable Unit (OU) 5
             Elmendorf Air Force Base, Alaska:
             STATEMENT OF BASIS AND PURPOSE

             This Record of Decision (ROD) presents the selected remedial action for OU 5
at Elmendorf AFB. It was developed 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), 42 U.S.C. §9601 et seq..
and, to the extent practicable, in accordance with the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP), 40 CFR §300 et seq. The attached administrative record
index (Appendix A) identifies the documents upon which the selection of the remedial action
is based.

             The selected remedy  includes passive extraction of seep water, natural
attenuation for Upper aquifer and surface water, institutional controls for upper aquifer water,
and sampling of water and sediment.  The U.S. Air Force, the U.S. Environmental
Protection Agency (U.S. EPA), and the State of Alaska, through the Department of
Environmental Conservation (ADEC), concur with the selected remedy.

             ASSESSMENT OF THE SITE

             Actual  or threatened  releases of hazardous substances (fuels  and fuel
constituents) from this OU, if not addressed by implementing the response action selected in
this ROD, may present an imminent or substantial endangerment  to public health, welfare, or

Elmendorf AFB OU 5 Record of Decision                1

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the environment.  Specific hazardous substances include jet fuel, gasoline range organics,
benzene, and trichloroethylene (TCE) (from upgradient sources).


              DESCRIPTION OF THE SELECTED REMEDY


              The selected remedy was chosen from many alternatives as the best method of
treating contaminated soil, sediment, groundwater, and surface water in OU 5.  It will
address the risks to health and the environment caused by the hypothetical exposure of a
future resident to contaminated groundwater and the possible exposure of animals and
transient humans to contaminated water from surface seeps.  The selected remedy  will
address this risk by reducing contamination to below cleanup levels established for OU 5.
Contamination in other OUs will be addressed in additional RODs.


              The major components of the selected remedy include:
              •      Contaminated seep water in the western and middle portions of the OU
                     will be passively drained using horizontally inserted extraction wells in
                     the bluff.  The water will flow to a constructed wetland, currently
                     planned to be built in the snowmelt pond. A layer of material such as
                     gravel will be placed over the sediments which contain PCBs in order
                     to isolate the contamination.

              •      Approximately 3,000 cubic yards of soil contaminated with fuel
                     products will be excavated and treated at an on-base treatment facility
                     to reduce contaminant concentrations below cleanup goals.  The treated
                     soil will be reused on base either to fill  the excavation or for general
                     fill.

              •      Natural attenuation will be relied upon to attain cleanup levels in  the
                     contaminated upper aquifer and surface  water other than seep water,
                     including the beaver pond wetland area.

              •      Institutional controls that prohibit use of the upper aquifer will ensure
                     that people will not be exposed to contaminated groundwater until
                     cleanup goals are achieved.

              •      Groundwater, seep water, and surface water will initially be sampled
                     on a quarterly basis.  Sediment will be sampled annually.  Results of

ElmeixJorf At-'B OU 5 Record of Decision                2

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                    the monitoring program will be assessed annually for at least the first 5
                    years to determine if cleanup levels have been achieved.  If cleanup
                    levels have not been reached, aggressive actions such as air sparging
                    with soil vapor extraction or active extraction with air stripping may be
                    necessary.  Bio venting of soil is an additional option that could treat
                    soil contamination.   If there are any  significant differences between the
                    actions  being taken as part of this ROD, an explanation of significant
                    differences or a ROD amendment will be issued.
              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 remedial action,  and is cost-effective.  This remedy utilizes permanent
solutions and alternative treatment technologies to the maximum extent practicable, and
satisfies the statutory preference for remedies that employ treatment that reduces toxicity,
mobility, or volume as a principal element.  Pursuant to  Executive Order 11990 and the
authority delegated by SAFO 780-1,  and taking into  account the information contained in the
ROD the Air Force finds that there is no practicable alternative to construction in the wetland
area set forth in the selected remedy  and that the selected remedy  includes all measures to
minimize harm to  the wetlands.

              Because the remedy will result in hazardous substances remaining on-site
above health-based levels, a review will be conducted within five years after commencement
of remedial action. The review will  ensure that the remedy continues to provide adequate
protection of human health and the environment.
Elmendorf AFB OU 5 Record of Decision

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                LEAD AND SUPPORT AGENCY ACCEPTANCE
                      OF THE RECORD OF DECISION,
             ELMENDORF AIR FORCE BASE, OPERABLE UNIT 5
This signature sheet documents agreement between the U. S. Air Force and the United States
Environmental Protection Agency on the Record of Decision for Operable Unit 5 at
Elmendorf Air Force Base.  The Alaska Department of Environmental Conservation concurs
with the Record of Decision.
 HN S. F/IRFIELD,  Lt Gen, USAF                    Date
'hairman/ HQ PACAF
nvironrrental Protection  Committee
Elmendorf AF3 Of 5 Record of Decision

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                 LEAD AND SUPPORT AGENCY ACCEPTANCE
                       OF THE RECORD OF DECISION,
              ELMENDORF AIR FORCE BASE, OPERABLE UNIT 5
This signature sheet documents agreement between the U. S. Air Force and the United States
Environmental Protection Agency on the Record of Decision for Operable Unit 5 at
Elmendorf Air Force Base. The Alaska Department of Environmental Conservation concurs
with the Record of Decision.
 ,HUCK CLARKE.                                Date
Regional Administrator
Region X
U.S. Environmental Protection Agency
Elmendorf AFB OU 5 Record of Decision

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                 LEAD AND SUPPORT AGENCY ACCEPTANCE
                       OF THE RECORD OF DECISION,
              ELMENDORF AIR FORCE BASE, OPERABLE UNIT 5
This signature sheet documents agreement between the U. S. Air Force and the United States
Environmental Protection Agency on the Record of Decision for Operable Unit 5 at
Elmendorf Air Force Base.  The Alaska Department of Environmental Conservation concurs
with the Record of Decision.
                        LCX:                     / - 5.
JANICE' AD AIR                                   Date
Regional Administrator
Southcentral Regional Office
Alaska Department of Environmental Conservation
Elmendorf AFB OU 5 Record of Decision

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                          PART II.  DECISION SUMMARY

              This Decision Summary provides an overview of the problems posed by the
contaminants at Elmendorf Air Force Base (AFB) Operable Unit (OU) 5.  It identifies the
areas considered for remedial response, describes the remedial alternatives considered, and
analyzes those alternatives compared to the criteria set forth in the National Contingency Plan
(NCP).  This Decision Summary explains the rationale for selecting the remedy and how  the
remedy satisfies statutory requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA).

1.0           SITE DESCRIPTION

1.1           Physical Description

              Elmendorf AFB is located approximately two miles north of downtown
Anchorage.  The base provides defense for the United States through surveillance, logistics,
and communications support.  OU 5 is located along the southern boundary of Elmendorf
AFB (see Figure 1-1), and covers an area over 7,000 feet long and over 1,200 feet wide.

              OU 5 is geographically diverse.   In the western part of the OU, a steep bluff
gives way to a broad flat area that ends in Ship Creek. In the eastern area, a more gently
sloping bluff leads to a wetland called the beaver pond area (see Figure 1-2). The beaver
pond area is a wetland in the eastern part of OU 5 where there are several shallow connected
water bodies and marsh areas.  The central part of the OU is a transitional area with a bluff
and some surface water features, including the snowmelt pond  and a fish hatchery.  The
snowmelt pond is an elongate shallow water Uxiy measuring approximately 50 x 300 feet and
is located in the center of the OU.  It was formed by beavers backing up natural drainages.
It is called the snowmelt pond because snow is often piled on top of the bluff, in the area
near the  pond.
Elmendorf AFB OU 5 Record of Decision                1-1

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                                MUNICIPALITY OF ANCHORAGE
                    ELMENDORFAFB
              OPERABLE
                UNITS
           Figure 1-1. Location Map of Elmcndorf AFB, Alaska
Elmcndorf AI-'B OU 5 Record of Decision

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 RESIDENTIAL
                      SNOWMELT
                       PONO
SHIP CREEK^ INLETV^^X.J	,/$
           COMPANY  \  ^Sl.777^-^"'

            WELL    ctirrirAn      FISH
                    STEELFAB    HATCHERY
                      WELL

    KEY:


    	 BASL BCJNDARY

    	FUEL PIPELINE

    	 BLUFF  LINE

       @    WELL LOCATION
                                           Figure 1-2.  Land Uses and Well Locations

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              Runoff generally fio^s i^m north to south through the pU towards Shiip •".
Creek.  Drainage ditches facilitate runoff in the western area.  The snowmelt pond is an old
drainage ditch which has backed up and formed a broad, shallow pond.

              Portions of the land at the base of the bluff are in the flood plain of Ship
Creek.  Areas of the golf course can be temporarily flooded in periods of high flow of Ship
Creek.

1,2           Land Use

              Land uses vary across OU 5.  The primary land use throughout most  of the
OU is light industrial.  Diesel fuel, jet fuel, multiproduct fuel lines, and distribution lines are
located in OU 5 on top of the bluff (see Figure 1-2).  An Army Corps of Engineers (COE)
building  is .located near the western side of the OU, above the bluff.  Some military
residential units are located back from the bluff on the eastern and western sides of the OU.
Ship Creek flows from east to west along the southern edge of the base.

              Land uses between the base of the bluff and Ship Creek include designated
open areas, a railroad right of way, Post Road, a picnic area and golf course, and a fish
hatchery. Though there is a diversity of wildlife in OU 5,  there are no reported rare or
endangered species in OU 5.  During the winter, the golf course is used as a cross-country
ski area, and a hill on the eastern side of the OU is a popular sledding area.  A snowmelt
pond  is  located on Alaska Railroad Company land between the base and the  railroad tracks
near the  middle of the  OU.  A commercial/industrial area that is part of the  Municipality of
Anchorage is located just south of OU 5.  There are no known historic buildings or
archaeologic sites in OU 5.
Elmendorf AFB OU 5 Record of Decision                1 -4

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1.3           Hydrogeologv and Groundwater Use

              OU 5 is located in a glacial outwash plain composed predominantly of sand
and gravel.  There are two aquifers—an unconfined upper aquifer and a confined lower
aquifer—hydrologically separated by an impermeable layer called the Bootlegger Cove
Formation (See Figure 1-3).  The water table (upper aquifer) is approximately 30 feet below
the ground surface above the bluff and is composed of sand and gravel and is highly
permeable.  The thickness of the sand and gravel varies, depending on the topography.  On
top of the bluff the sand and gravel is approximately 50- to 80-feet thick.  The saturated
thickness is  approximately 20 to 50 feet.  Near Ship Creek, where the groundwater is
shallow, the formation is as little as 10 feet thick with a 5-foot saturated thickness.
Groundwater flows from north to south, discharging out of the bluff as groundwater seeps in
several locations.  The water table aquifer is not used for any purpose on base. Its future
use, even if there were no impact, is limited because of the higher yield of the lower aquifer.
The aquifer quality is locally degraded by contaminant sources.  More detail on impacts is
provided in Section 3.0.

              Groundwater  in the upper aquifer flows toward Ship Creek.  Results from two
stream gaging stations indicate that Ship Creek gains water along its course most of the year.
Some groundwater flowing toward Ship Creek contributes to creek flow.  Groundwater that
does not discharge as seeps or to the creek becomes underflow.  Sampling during the
remedial investigation indicated  no contamination in Ship Creek

              As indicated above, the Bootlegger Cove Formation is a layer of clay, silt, and
silty clay that separates the upper and lower aquifer.  This formation acts as a hydraulic
aquitard and is from 5- to over 200-feet thick in OU 5.

              The lower aquifer is confined by the Bootlegger Cove  Formation and is up to
550 feet thick. The top of the aquifer is found approximately 150 feet below  the surface.
This aquifer is used as a source  of water but sampling has not indicated any contamination.

Elmcndorf AFB OU 5 Record of Decision                1-5

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      N
s.
c
a,
>
o
c
o
a
     NOT TO SCALE
                      Knik Arm
                                                                                        Groundwater Flow ^
                                        Corps of
                                       Engineers
                        Water Table
                 Typically 5 to 20 feet
                below ground surface


          Bootlegger Cove Formation
          Typically 5 to 200 feet thick
Unconfined Aquifer
(Sand and Gravel)
Typically 10 to 80 feet thick
with a 5- to 50-foot saturated thickness

Confined Aquifer
(Sand) Found 150 to 200 feet
below ground surface
and 550 feet thick
                                      Figure 1-3. Hydrogeologic Conceptual Model
              ELMENM.OnW • 12/7/M • JH . SAC

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The locations of water wells in OU 5 are shown on Figure 1-2.  Four base wells, two of
which are located in OU 5, pump water from the confined lower aquifer, approximately 150
feet below ground surface. Two wells are  located south of the fish hatchery, another above
the bluff line between the snowmelt pond and the COE building, and the fourth below the
bluff, near where a pipeline crosses Ship Creek (see Figure 1-2). Water from the base wells
is used for drinking water. Hatchery wells are used to regulate fish hatchery water
temperature  and quality. Three additional wells  screened in the lower aquifer were identified
in the heavy industrial area southwest of OU 5.  This  industrial area is a part of the city of
Anchorage and is not located on Elmendorf AFB.
Elmendorf AFB OU 5 Record of Decision                1-7

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2.0          SITE HISTORY AND ENFORCEMENT ACTIVITIES

2.1          Identification of Activities Leading to Current Contamination at OU 5

             As part of the ongoing mission at Elmendorf Air Force Base, aircraft are
regularly refueled and many of the fuel lines are located in OU 5. These fuel lines have, at
times, leaked fuel into the soil and groundwater surrounding the pipelines.   Before the leaks
could be detected, fuel product and fuel constituents such as benzene migrated from the leak
to the water table. This migration from source areas is the primary cause of contamination
at OU 5.  A schematic of the principal transport mechanisms are shown on Figure 2-1 and
are discussed below.  Understanding transport is important because the contaminants and
risks are not always associated with the source area, but with the area where an exposure is
possible.  The risk assessment considered the  current and future transport of contaminants to
potential receptors.

             Dissolved aqueous transport.  The principal transport mechanism of solvents
and fuels contamination is by aqueous solution in groundwater and surface water.
Contaminants can dissolve into solution when water passes over contaminated soil.  As
contaminated water migrates, it can deposit contaminants on the soil  through which it passes.
This appears to be the case with the diesel contamination found in soil  and  sediment in the
middle of the OU.

             Volatilization.  Contaminants,  such as volatile organic compounds (VOCs)
and lighter fuel constituents, can become  gases, either volatilizing into  the soil or directly to
the atmosphere.  Concentrations of VOCs in soil gas were detected at relatively  low
concentrations (1 to 10 /ig/L) indicating that volatilization is not a significant migration
pathway.

             Colloid/Particle Transport.  Contaminants adhered to particles in water can
be transported by entrainment  if runoff washes away soil or if surface  water is churned  up.

ElmcmJorf AFB OU 5 Record of Decision                2-1

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                                                                                                               VOLATILIZATION
                                                                                                                                                    UPOFlAOIENT
                                                                                                                                                     SOURCES
                                                                                             INTEnBEODElT LAYERS
                                                                                             OF SILTS AND GRAVELS
                                                                                                         INTERBEDOEO LAYERS
                                                                                                         OF SANDS AND GRAVELS
SHALLOW AQUIFER
                               •.'•/.•.'ALLUVIUM: SANDS. GRAVELS. SILTS
                                                                            GLACIAL OUTWASH:
                                                                            INTERBEODED LAYERS OF
                                                                            SANDS AND GRAVEL
                                                       BOOTLEGGER COVE FORMATION (CONFINING LAYER):
                                                       INTERBEDDED LAYERS OF SILTS. CLAYS. AND SILTY CLAYS
                                                                                                                 GROUNDWATER FLOW
LEGEND                   g SCREEN

UPPER AQUIFER WATER TAOLE

SURFACE/WELL WATER

LEAKING CONTAMINANTS

DISSOLVED CONTAMINANTS

FLOATING CONTAMINANTS LIGHTER THAN WATER (LNAPLS)
IN CONCENTRATIONS GREATER THAN THEIR WATER SOLUOILTTY

DIRECTION OF QROUNDWATER FLOW

CONTAMINANT PATHWAY
                                                       DEEP ARTESIAN AQUIFER
N X X

 N;
                                                                                                   GROUNDWATER FLOW
                                                                                                                                                      NO SCALE
                                 Figure 2-1.   A  Schematic of Principal  Transport Mechanisms in OU  5

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Particle transport is a potential transport mechanism for PCBs in the snowmelt pond if the
sediments are disturbed.

             In OU 5, the discovery of hydrocarbon seeps in the early 1980s was the first
indication of the leaks.  From the leak, fuel migrated in a southerly direction seeping from
the bluff face located along the southern end of OU 5. When leaks were identified they were
repaired and residual hydrocarbon was recovered to the extent possible.  Hydrocarbon was
recovered at the bluff face using absorbents and  skimming any floating product found on
surface water drainages. The remaining hydrocarbon and hydrocarbon constituents are the
primary cause of environmental impact at OU 5.

             Environmental investigations have been conducted at OU 5 since the mid-
1980s.  Several small-scale studies discovered evidence of contamination in various parts of
OU 5. The first investigation to examine contamination throughout the whole area was done
by Black and Veatch in 1988.

             The  Black and Veatch study was followed in 1992 by the remedial
investigation (RI) completed by CH2M Hill.  The RI determined the  nature and extent of
contamination, and the  potential risks to public health and the environment.  The results were
compiled and analyzed  in the RI report.

             Radian Corporation conducted two investigations while completing the
Feasibility Study (FS).  In one study, the extent of PCB contaminants in the snowmelt pond
water and sediment was identified. In the other study, the capacity of the beaver pond
wetland area to naturally attenuate contamination was assessed.  In addition, the Elmendorf
Bioenvironmental Engineering Services Group (BESG) have been collecting groundwater and
surface water samples from throughout Elmendorf AFB since 1987.

             Six CERCLA sites  in the OU  were identified  based on the location of
hydrocarbon seeps  and  known leaks.  The location of the sites is shown on Figure 2-2.

clincnd,--!' AFB OU 5  Refund of Decision                2-3

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CORPS OF
ENGINEERS
  BLDG.
w>
   SHIP CREEK
     LEGEND:


            PETROLEUM POTENTIAL STUDY AREAS
      i-SB-a  SPECIFIC SOURCES  ARE POINT SOURCES
            WITHIN THESE  STUDY AREAS

      	   SEEPS

      	  OASE BOUNDARY
0            1200

  SCALE IN FEET
                                    Figure 2-2.  Potential Source Areas in OU 5

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              Three of the source areas were identified based on leaks in buried tanks and
pipelines.  In the late 1950s at Source ST37, several thousand gallons of diesel fuel leaked
from a fuel line south of the U.S. Army Corps of Engineers (COE) building. Over the
years, thousands of gallons of fuel have been recovered from hydrocarbon seeps using
absorbents at the face of the bluff, immediately south of this site.  The ST38 leak occurred in
the mid-1960s in a JP-4 jet fuel pipeline.  As with ST37, migration led to seepage of fuel
sheens from the bluff, east of the snowmelt pond; no fuel was recovered.  ST46 had a
pipeline leak occur in 1978 when JP-4 jet fuel seeped into the wetlands at the base of the
bluff and  Ship Creek.  After the leaking pipe was repaired, fuel continued to seep from the
bank into the beaver pond.  All leaks have been repaired and the pipelines and tanks are
given annual checks and triannual detailed evaluations to  locate leaks.

              At a fourth site (SS42), an estimated  8,000-gallon, one-time spill of diesel fuel
occurred in March 1976.  Most of the fuel was recovered off the frozen ground.   The final
two source areas are identified as SD40, and SS53 and are directly upgradient of where fuel
seeped from the bluff.  At SD40, oil was reported seeping out of the bank near the railroad
tracks and flowing through a marsh into Ship Creek during the  late-1960s.  (However, the
Remedial  Investigation did not find any residual contamination in Ship Creek.) The source
of this oil could not be  determined.  SS53, another  fuel seep of unknown origin, was
observed during the spring thaw for an unspecified  number of years. The seep flowed into a
drainage ditch parallel to Post Road.  The potential  source area, as shown in Figure 2-2, is
in the middle of the OU along the railroad right of  way.

              Solvent constituents, primarily TCE,  are detected in the upper aquifer
groundwater in OU 5.  The solvent sources are located upgradient of the OU, in areas where
solvent spills 01 ..IL^osal occurred in the past.  Source areas include shop drains (OU 3) and
sanitary landfills (CU 1, OU 2 [ST-20]).  The general locations of source areas are  shown on
Figure 2-3.   Solvents from these upgradient source  areas have migrated toward OU  5 in the
groundwater. Plumes from these source areas are well-defined geographically, and  OU 5 is
Ulmendurf AI-"B OU 5 Record of Decision                2-5

-------
m

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-------
known to capture approximately 90% of the groiindwater flowing from Elmendorf AFB,
including all of the areas shown on Figure 2-3.

             Upgradient source areas are being studied as part of the remedial investigations
of each individual OU and as part of State/Elmendorf Restoration Agreement (SERA) site
studies. However, the impacts of the upgradient sources on OU 5 were evaluated in a
groundwater model.  The results of the model (discussed later) were used to predict future
groundwater quality at OU 5 and to select a remedial action to treat future conditions at
OU 5.

2.2          Regulatory and Enforcement History

             Based on the results of environmental investigations, Elmendorf AFB was
listed on the National Priorities List by the U.S. Environmental Protection Agency (U.S.
EPA) in August 1990.  This listing designated the facility as a federal site subject to the
remedial response requirements of CERCLA, as amended by the Superfund Amendments and
Reauthorization Act of 1986.  On 22 November 1991,  the USAF, U.S. EPA, and the Alaska
Department of Environmental Conservation (ADEC) signed the Federal Facilities Agreement
(FFA) for Elmendorf AFB. The contaminated areas of Elmendorf AFB were divided into
seven OUs, each to be managed as a separate region and investigated according to varying
schedules. There are six RCRA source areas along the upgradient edge of the western and
central portions of OU 5.  All six of these source areas are currently going through RCRA
clean closure.  However,  if contamination has reached the groundwater, it will be addressed
under CERCLA and handled as part of the action at OU 5.

             In accordance with the FrA, a Remedial Investigation (RI) of OU 5 was
conducted in the summer of 1992. The RI determined the nature and extent  of the
contamination, and the potential risks to public health and the environment.  The results were
compiled and.analyzed in the RI report.  The RI concluded that fuel, fuel  constituents, and
low levels of solvents were found  in soil and groundwater in OU 5.  Fuel constituents were

Elmendorf AFB OU 5 Record of Decision               2-7

-------
also detected at relatively low concentrations in surface water ditches and in the beaver pond
wetland area.  The impacts to soil were found in the areas where impacted ground water
seeped from the bluff.  Impacts in the soil at the source areas (location of the leaks) were
low and did not pose a threat to human health or the environment.

             Based on the RI results, No Further Action (NFA) Decision Documents were
prepared, signed, and approved in August 1994  for the soil in the potential source areas in
OU 5 except ST37, the western area diesel leak.  The NFA sites are ST-38, SS-42, SS-53,
SD-40, and ST-46.

             Two investigations were conducted while completing the FS.  One study
investigated the extent of PCB contamination in  the snowmelt pond "water and sediment.  The
other study assessed the capacity of the beaver pond wetland area to naturally attenuate
contamination.  The Final RI/FS was submitted  in March, 1994. A Proposed Plan was
distributed to the public on 6 June 1994, and a public meeting to discuss the plan was held
on 23 June 1994. A Draft OU 5 Groundwater Modeling Report (GMR) was issued on
4 August 1994.

2.3          Role of Response Action

             The CERCLA process described above is intended to identify solutions to
contamination issues where they exist.  The remedial action described in this ROD  addresses
threats to human health and the environment posed by contamination at OU 5.  The RI/FS
and the Groundwater Modeling Reports define these threats as primarily groundwater
contaminants. The OU 5 GMR was used to further document the appropriateness of  the
decisions made in this ROD. At this time, grouncr-ater will  be monitored.  Further response
actions, coordinated with regulatory agencies, could be considered  if monitoring finds
concentrations of contaminants greater than predicted by the GMR.
Elmendorf AFB OU 5 Record of Decision                2-8

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2.4          Community Participation


             Public participation has been an important component of the CERCLA process

at Elmendorf AFB.  Activities aimed at informing and soliciting public input regarding base

environmental programs include:
                    Environmental Update.  Environmental Update is a newsletter
                    distributed to the community and interested parties.  It discusses the
                    progress that has been made on OUs and advises the public about
                    opportunities to provide input concerning decisions to address
                    contaminated areas of the base.  Aspects of the OU 5 CERCLA
                    progress have been published  in this update.

                    Community Relations Plan.  The base environmental personnel
                    maintain and regularly update a Community Relations Plan.  It
                    describes how the base will both inform the public of base
                    environmental issues and solicit public comment on base environmental
                    programs.

                    The Technical Review Committee.  Base personnel meet quarterly
                    with representatives of the community to discuss base environmental
                    programs and solicit their comments.

                    Public Workshops.  On 5 February 1992, approximately 75 people
                    attended a public workshop where base personnel discussed base
                    environmental programs and  encouraged public participation.

                    Videotape.  Base personnel made a videotape describing base
                    environmental activities.  The tape is used with both internal (to the
                    base) and external audiences.

                    Community Council Briefs.  The Air Force regularly  provides briefs
                    to the community council on the progress of the Installation Restoration
                    Program (IRP).  Specific presentations were made regarding the
                    progress at OU 5 and on the planned remediation.

                    Speakers Bureau. The 3rd  Wing Public Affairs Office maintains a
                    speakers bureau capable of providing speakers versed in a variety  of
                    environmental subjects to military and civic groups.
Elm-Jiidorf AF3 Of 5 Record of Decision                2-9

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                    Newspaper Releases.  News releases were published on significant
                    events during the IRP.  News releases were made announcing all public
                    meetings that were held to discuss proposed remedial actions.

                    Information Repositories.  Public access to technical documents was
                    provided through information repositories located at the Bureau of Land
                    Management's Alaska Resources Library and  the University of Alaska
                    at Anchorage's Consortium Library.  The information in the
                    repositories was also maintained in the administrative record.  The
                    remedial action was selected based on the information held in the
                    administrative  record.

                    Display Board.  During public functions, a display board, showing key
                    elements and progress of the Elmendorf IRP,  was used to communicate
                    technical issues to the public.  It was used during both on-base and off-
                    base events.

                    Proposed Plan.  The proposed plan was distributed to the public on 6
                    June 1994, a public meeting was held 23 June 1994, and the public
                    review period  was from 6  June to 6 July 1994. The plan was approved
                    on 7 July 1994.

                    Public Notice. Public notices have been issued prior to all significant
                    decision points in the IRP.   For OU 5, public notice was issued for the
                    proposed plan in the Anchorage Daily News (6/1/94) and the Sourdough
                    Sentinel (6/3/94).

                    Mailing List.  A mailing list of parties  interested in the restoration
                    program is maintained  by the base.  Notices and publications (news
                    releases including the OU  5 proposed plan meeting) was released via
                    the mailing list.

                    Responsiveness Summary. Public comments were received on the
                    proposed plan. The Air Force maintained a record of all comments
                    and has published responses to the comments in this Record of
                    Decision.
All decisions made for OU 5 were based on information contained in the Administrative
Record.
Elmendorf AFB OU 5 Record of Decision               2-10

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3.0          SITE CONTAMINATION, RISKS, AND AREAS REQUIRING
             RESPONSE ACTIONS

             This section identifies the areas which may require remedial action.  These
areas were chosen based on the risk that contaminants pose to human health and the
environment. The basis of this analysis is the data collected during the Remedial
Investigation (RJ) which identified the nature and extent of contamination in OU 5.

3.1          Nature and Extent of Contamination

             During the RI, samples of soil, soil gas, groundwater, sediment, and surface
water were collected and analyzed for organic and inorganic constituents.  Significant levels
of organic contaminants were detected in the soil, sediment, seeps, and groundwater. The
contaminants include:  fuel products (benzene), volatile organic compounds (VOCs),
inorganic compounds, and semivolatile organic compounds (SVOCs). Tables 3-1,  3-2, and
3-3 show the contaminants detected and the frequency of detections. Figures are referenced
below that show the location of detected constituents.

             In the upper aquifer and in some seeps, fuels were the most frequently
detected contaminants in OU 5.  Concentrations of diesel (ranging from not detected  [ND] to
290 ng/L), gasoline (ND to 700 /zg/L) and jet fuel (ND to 760 /zg/L) were found.  VOCs
were also  found in groundwater  samples at the eastern and western portions of the  OU.
Trichloroethylene (TCE) was the most commonly detected VOC (ranging from ND to 52
Mg/L). Figures 3-1 and 3-2 show the distribution of organic compounds in groundwater.
Inorganics were detected in a few groundwater samples above  background. Barium and
manganese were the metals most often detected above background concentrations.  However,
only one manganese detection was significantly above background (one order of magnitude).
The source identification efforts, operational history  of the base, and the RI revealed no
source of manganese contamination in OU 5.  Therefore, the results are thought to be
Elmendorf AFB OU 5 Record of Decision               3- 1

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                                  Table 3-1



                Potential Contaminants of Concern — Water
Contaminant
Maximum
Concentration
MCLs
Frequency
(Detections//?
Samples)
Groundwater (Maximum Concentration and MCLs - pg/L)
1 , 1 , 1-Trichloroethane
1 , 1 ,2,2-Tetrachloroethane
Benzene
Ethylbenzene
JP-4
TFH Diesel
TFHGas
Toluene
Trichloroethylene (TCE)
Xylenes, total
bis(2-ethylhexyl) phthalate
tert-butyl methyl ether
Di-n-butyl phthalate
Diethyl phthalate
N-nitrosodiphenylamine
1,1-Dichloroethane
2-Methylnaphthalene
Aluminum1"
Barium
Calcium"
Chloroethane
Iron"
Manganeseh
Naphthalene
Potassium6
Seleniumh
Vanadium*1
9.4
8
8.5
16
760
290
700
1.4
52
39
20'
0.56
1
1
5
1.3
9
68
103
94,700
1.3
12,600
4,280
13
2,070
2.5
5
200
—
5
700
—
—
—
1,000
5
10,000
6
—
—
—
—
—
—
50-200
2,000
—
—
300
50
—
—
50
—
1/7
1/7
4/16
2/10
4/23
7/28
3/17
2/8
6/14
2/10
5/26
1/7
3/13
3/25
2/15
1/3
1/3
2/3
4/6
1/5
1/3
3/4
3/6
1/3
1/5
2/5
2/5
Elmendorf AFB OU 5 Record of Decision
3-2

-------
                                              Table 3-1

                                            (Continued)
Contaminant
Maximum
Concentration
•;7MCLs."---;;- •
Frequency
(Detections/*
Samples)
Surface Water (Maximum Concentration and MCLs - /ig/L)
1,1,1 -Trichloroethane
1,1-Dichloroethane
1 ,2-Dichloroethane
4-Methylphenbl (p-cresol)
Benzene
Bromomethane
Ethylbenzene
JP-4
Naphthalene
TFH Gas .
Toluene
Trichloroethylene (TCE)
Xylenes, total
trans- 1 ,2-Dichloroethene
1 , 1 ,2,2-Tetrachloroethane
1.9
2.3
2.6
7
1.5
13
12
770
1
400
27
6.6
19
1.9
4.3
200
—
5
—
5
—
700
—
• —
—
1,000
5
10,000
100
—
2/5
1/5
1/5
1/4
2/10
1/5
1/5
1/5
1/3
1/3
3/9
4/10
1/5
1/3
2/5
a  Resampling of groundwater showed no Bis(2-ethylhexyl) phthalate at well OU 5 MW-11, the site of the 20
   detection.
   Only those metals detected above background listed.
Elmendorf AFB OU 5 Record of Decision
5-3

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                                  Table 3-2



              Potential Contaminants of Concern — Sediment
Contaminant ; .
Maximum
Concentration
; Frequency
•/J(Detexiti^fjff:^-
.'.;:.:Samjples)"-"::'v' :";'•'•'
Sediment (Maximum Concentration - pg/kg)
2-Methy 1 naphthalene
4-MethylphenoI (p-cresol)
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Ethylbenzene
Fluoranthene
PCB-1260 (Arochlor 1260)
Phenanthrene
Pyrene
TFH Diesel
TFH Gas
Toluene
Xyleries, total
bis(2-ethylhexyl) phthalate
JP^
Naphthalene
100
89
230
59
91
58
63
120
930
130
1,600
270
150
7,400,000
700,000
26
6,200
240
100,000
69
2/10
1/5
1/5
1/5
1/5
1/5
1/5
2/5
3/10
1/5
4/6
3/10
1/5
2/5
2/3
1/5
2/5
1/5
1/5
1/5
Elmemlorf AFB OU 5 Record of Decision
3-4

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                                   Table 3-3
                  Potential Contaminants of Concern — Soil
"••• : "'•••• -Contairiinant
; Maxim um .•• v :.
• Concentration
Maximum
Background
Concentration8
Frequency
(Detections/;;
# Samples);
Soil (Maximum Concentration - /tg/kg, regardless of depth)
4-Nitrophenol
Diethyl phthalate
Pyrene
Di-n-butyl phthalate
Ethylbenzene
JP-4
TFH Gas
Toluene
Xylenes, total
bis(2-Ethylhexyl) phthalate
Benzo(k)fluoranthene
Fluoranthene
Phenanthrene
TFH Diesel
Benzene
2-Methylnaphthalene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h , i)pery lene
Chrysene
Indeno(l ,2,3-c,d)pyrene
4-Methylphenol (p-cresol)
100
49
280
39
202
14,000
310,000
64
3,940
180
180
300
240
1,160,000
14.9
48
63
200
330
160
100
240
98
51
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
1/5
2/6
3/8
1/1
3/12
2/11
5/18
3/18
4/12
3/3
2/2
2/2
2/2
11/26
2/6
1/1
1/1
1/1
1/1
1/1
1/1
1/1
1/1
1/1
Elniendorf AFB OU 5 Record of Decision
3-5

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                                              Table 3-3




                                             (Continued)
Contaminant :
. Maximum
Concentration
•Maximum
Background
Concentration3
Frequency^: •'.
(Peietxumstt
Samples) ?
Soil (Maximum Concentration - mg/kg) (Continued)
Aluminum
Arsenic
Barium
Beryllium
Calcium
Copper
Cadmium
Chromium (Total)
Lead
Manganese
Mercury
Potassium
Sodium
Selenium
Silver
Thallium
Zinc
19, 100 mg/kg
28.2 mg/kg
3,650 mg/kg
1.3 mg/kg
35,300 mg/kg
38 mg/kg
3.1 mg/kg
64 mg/kg
206 mg/kg
199,000 mg/kg
0.31 mg/kg
1,440 mg/kg
1,430 mg/kg
3.1 mg/kg
22 mg/kg
0.59 mg/kg
159 mg/kg
19,211
9.0
131.4
0.47
4,021
183
1.46
25.5
18.3
459.4
0.11
508.5
364.9
0.37
0.91
NE
49.9
1/38
1/38
10/38
3/38
10/38
4/38
1/38
1/38
21/38
8/38
2/38
1/38
14/38
3/38
1/38
5/26
3/38
a  Background value was 99% confidence limit for the mean for surface soil.



NE = Not established.




—  = Background concentrations provided for inorganic analytes.
ElmencJorf AFB OU 5 Record of Decision
3-6

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    WAST
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                                                                                         CORRIDR
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ORGANIC CONTAMINANTS
   DETECTED IN UPPER
' AQUIFER GROUNDWATER
   o	no	«o	500.
                                                                                                                                                ELWMX3BF Ate
                                                                                                                                               ANCHORAGE. ALASKA

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                                                                                                                                                                                       FIGURE 3-2


                                                                                                                                                                               OftOANIC  CONTAMINANIS

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-------
naturally occurring and are the result of geological variability typical of glacial outwash
plains.

              Surface water (ditch water, the snowmelt pond, and the beaver pond wetlands)
has been impacted by volatile organics.  Seeps are not considered surface water but
discharges from groundwater.  However, most concentrations are low (see Table  3-1) and the
compounds were generally detected in 20% of the samples.  The exception is TCE which
was detected in 4 of 10 samples.  A single detection of JP-4 (770 /ig/L) was found on a
puddle formed by seep water.  The puddle is technically surface water, but is not a body of
water like the  beaver pond wetland area or the snowmelt pond.  Figures 3-3  and  3-4 show
the distribution of organics in surface water.

              Sediment has been impacted in the beaver pond and snowmelt pond.
Semivolatile compounds are found in 20% of the samples tested with anthracene  having the
highest concentration (230 pig/kg) (see Table 3-2).  PCBs were  detected in 4 of 6 sediment
samples taken  at the snowmelt pond with a maximum concentration of 1,600 /ig/kg.  Volatile
organics and fuel hydrocarbons  were also detected with  xylene being the most prevalent VOC
and TFH-diesel being the most prevalent fuel hydrocarbon.  The distribution of organics
found in sediment are shown on Figures 3-3 and 3-4.

              Soil at different depths has been impacted by VOCs, semivolatiles, fuel
hydrocarbons,  and metals (Table 3-3).  The VOCs, toluene, xylene, and ethylbenzene were
detected in approximately 20% to 25% of the samples.  Most of the semivolatile  compounds
are found in a single sample set.  Otherwise semivolatile organics are found  sporadically.
The distribution and depth of organic compounds in soil are shown on Figures 3-5  and 3-6.

              Metals were found above background in soil (see Table 3-3).  Manganese had
the highest concentration at one location. Most  of the metals that exceeded background are
naturally found at high concentrations.  Very few concentrations of contaminants detected at
OU 5 were above background.  Lead and sodium exceeded background the greatest number

Elmendurf AFU OU 5 Record of Decision                3-9

-------
LfGCNO
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             ARE TOTAi UCTALS.
             DATA SHOWN ARE THC HIGHEST OBSfOVEO
             FROM TWO SOUNDS Of SAMPLING.
         FIGURE 3-3

   ORGANIC  CONSTITUENTS
DETECTED  IN SURFACE  WATER
        AND SEDIMENT
                                                                                                                                                                               CLMCM3ORF AfB
                                                                                                                                                                             ANOIOHAOE. ALASKA

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-------
of times.  Figures 3-7 and 3-8 show the distribution of inorganics in soil. Generally, higher
concentrations of the metals were found in organic rich soil.  Organic soils can adsorb and
concentrate metals so it is reasonable to conclude that the elevated concentrations are due to
natural accumulation through adsorption and not through impacts from base operations. This
conclusion is further supported by there being no historical evidence of sources that would
discharge metals.

              Detailed studies were performed at the beaver pond wetland and snowmelt
pond to determine if the impacts identified during the RI were, or could, affect the
environment.  Samples were taken of the sediment and water in the beaver pond and were
tested for microbial potential, adsorption, and chemistry.  The retention time and flow rate in
the wetland also was determined. This study concluded that the beaver pond was currently
treating the contaminant load entering  the wetland via groundwater discharge and has treated
water contamination for many years without a significant degradation of the wetland.   The
study estimated that the pond is 18 times larger than necessary to treat the current
contaminant load by natural processes.

              The snowmelt pond was studied to determine the extent of PCB contamination
in the pond's water and sediment.  PCBs were not detected in any water samples.  Total
organic carbon (TOC) was also measured at sediment sampling locations because PCB
sediment standards vary according to accompanying TOC concentrations.  TOC binds the
PCBs to sediment material,  reducing its ability to migrate. PCB concentrations are below
standards  at three locations but above standards at two locations where TOC is high.  There
was no geographical pattern to the locations where TOC is not sufficient to bind the PCBs
(reflected in lower standards at these locations).
       AFB OU 5 Record of Decision               3-14

-------
                                                                                  CORRIDOR  SP?/80lS'

            ^r.o,               .^^

             -^a' :;"^^:;:-^3^                                      ' A^^
                 '                '      '      '     '      '           "'                                    ~
          POST''ROAD,  CO'RRIDOR"'"^'-1^"^
                                      INDlj^TRIAL  Alfi'A
                                                                                                                                   FIGURE 3-7

                                                                                                                               INORGANIC  ELEMENTS
                                                                                                                              DETECTED IN  SOIL ABOVE
                                                                                                                                BACKGROUND LEVELS
                                                                                                                                o    xo    
-------
           ^•'^m-^m^                             ^RV      ••   x  >wy   :
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-------
3.2          Risk Evaluation


             Based on the concentrations of contaminants detected during the RI, human

health and environmental risk assessments were performed to determine if areas should be

considered for remedial action.  All concentrations of contaminants, including all potential

contaminants of concern, whether exceeding Applicable or Relevant and Appropriate

Requirements (ARARs) (discussed later) or not,  were included in the risk assessments.


             Human  Health Risk Assessment (HRA)


             By determining under what land use conditions people are potentially exposed

to what chemicals, for  how long,  and by what pathways of exposure, the cancer and

noncancer risks were determined in the RI/FS.


             Exposed Populations and Exposure Pathways—Listed below are four possi-

ble exposure pathways  to contamination.  Details on the parameters used in the Health Risk

Assessment are shown  on Table 3-4.
                    Residential (Current and Future Potential). The HRA evaluated
                    exposure of residents to contaminated surface soil through direct
                    contact (incidental ingestion and dermal absorption) and inhalation of
                    dusts.  Their exposure to lower and upper aquifer groundwater through
                    inhalation (showering), ingestion, and dermal contact (showering) was
                    also evaluated.

                    Current and Future Short-Term Workers. The HRA evaluated
                    exposure of workers to contaminated subsurface soil through direct
                    contact (dermal absorption and incidental ingestion) and inhalation of
                    vapors from the soil.

                    Exposure of Current and Future Recreationalists (Children).
                    Exposure of children was evaluated with respect to contaminated
                    sediment (ingestion and dermal absorption) and contaminated surface
                    water (ingestion,  dermal absorption, and inhalation of volatiles from
                    surface water).
ElmiMidorf AFB OU 5 Record of Decision                3-17

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              Table 3-4
Parameters Used in the Risk Assessment

•'"'• • '" • ' '• ''•; . '''•'•••}•••'.'• ''•'•\'^--'^'- \-\ "•'!•:• '•"
:' :y ' -' :"•• -•:•.• '? -vi''-y:-:: "•:":*::••"" ••-• >• '' '••-''. •
' - ' :''-. ' •'•• ••....."-.-- • '.•:;•;•". '•• ^ •.•:$:'#•: 'roS ':'.-•: '::^'.
..;•• |- ^^^:••ExIwsure :Parainet(ew|||^s^;::ia-:
' :.' '.:•;:,;: -.'• •.;•• ; ::"!:'-": ' !:•; •b|ll;;:;:;l|:;s-:C:l>::
Exposed Individual V ".'•*'•• ' f ;:?ll|ill?%?:?-: '
Body Weight (kg)
Soil Ingestion Rate (mg/day)
Exposed Skin Surface Area (cm2)
Adherence to Skin Factor (ing/cm2)
Days/year exposed (Inhalation and Ingestion)
Years exposed
Days/year exposed
Dust inhalation rate (mVday)
Paniculate concentration (/*g/m3)
Water Ingestion Rate (L/day)
Time in Water (min/day)
Sediment Ingestion Rate (mg/day)

^libsurfaci§:-S6ii;l;:-::


'- French -W§!ii|:f::;-
70
480
5,000
1.0
24
5
NA
NA
NA
NA
NA
NA
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iPll!:i:^i^c^
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l:iil^iE:i;:;;iii
IX;2!PI:lResiicSfe
15 (0-6 yr)
70(>6yr)
200 (0-6 yr)
100(>6yr)
5,800
1.0
'350
30
350
20
50,30
NA
NA
NA
Pathway
iiilillp
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;:|;A;yierag||:

70
100
5,000
0.2
275
9
40
20
50, 30
NA
NA
NA

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70
NA
23,000
NA
NA
30
350
15
NA
2
15
NA
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diwaW'lH I

||A^eriij|e 1
||:||i|:||y
lehtf ;-.;;:;||| 1
70
NA
20,000
NA
NA
9
275
15
NA
1.4 '
10
NA

lM:::ttlii:::-,5::
m:?w&trir}
.. - - ;-......;. . :. .-. . .- .... ..; -.-. . .

& Recreational
glSIUlerliy..;--
35
NA
3,900
Sediment
10,000 Water
1.0
NA
5
26
NA
NA
0.05
60
100

-------
                     Exposure of Recreationalists. The HRA evaluated recreationalists'
                     exposure to contaminants through the consumption of fish caught in
                     Ship Creek.
              Exposure Assumptions—Risk can be calculated both for the average exposure
and the reasonable maximum exposure (RME) of the population.  All chemicals detected
during sampling were evaluated as potential sources of cancer and noncancer health risks.  In
the case of metals, risks were only calculated if the metals concentrations exceeded
background concentrations.  Average exposure risks were assessed using the arithmetic
average concentration at the site.  RME risks were assessed using the 95% upper confidence
limit of the arithmetic mean concentration in soil, sediment,  surface water,  or ground water in
subareas such as the beaver pond wetland area.

              Conservative assumptions were used to avoid underestimating risk.  For
example, the HRA assumed that future residents would live where the contaminants are
located and they would  drink and shower with the contaminated, upper aquifer ground water.
This is a highly conservative assumption since the topography of the bluff and wetlands at
the base of the bluff would not allow for construction of residences  along the bluff where
contamination is greatest. In addition, the upper aquifer is unlikely to be used as a water
supply because of its poor yield relative to the lower, confined aquifer.

              Using exposure levels and standard values for the toxicity of contaminants,
excess lifetime cancer risks (ELCRs) and hazard indices (His) were calculated to describe
cancer and noncancer risks, respectively. The ELCR is the additional chance that an
individual exposed to site contamination will develop cancer during  his/her lifetime.  It is
expressed as a probability such as 1 x 10"6 (one in a million).

              The HI estimates the likelihood that exposure  to the contamination  will cause
some negative health effect.  An HI score above one indicates that some people exposed to
the contamination may experience at least one negative health effect.
Elmendorf AFB OU 5 Record of Decision               3-19

-------
              ELCRs and His were calculated using  Reference Doses (RfDs) and Cancer
Slope Factors (CSFs) which represent the relative potential of compounds to cause adverse
noncancer and cancer effects, respectively.

              Two sources of RfDs and CSFs were used for this assessment.  The primary
source was Integrated Risk Information System (IRIS) database, the U.S. EPA repository of
agency-wide verified toxicity values. If a toxicity value was not available through IRIS, then
the latest available quarterly update of the Health Effects Assessment Summary Tables
(HEAST) issued by the U.S. EPA's Office of Research and Development was used as a
secondary source.  For some chemicals detected at OU 5, no toxicity value from IRIS or
HEAST was available, and toxicity values were provided by the U.S.  EPA Region X as
provisional RfDs and cancer slope factors.

              Table 3-5 summarizes the highest human health risks discovered in the HRA.
The risks are based on exposure to soil and groundwater.  Locations where the risk exceeds
10"6 (i.e.,  10"*, 10"5) are shown  on Figure 3-9. At two locations in the central part of the OU
groundwater quality exceeds standards, but risk was less than 10~5.  The only scenario that
generates a noncancer HI value exceeding one, or total excess lifetime  cancer risks greater
than 1  x 10^, is when future residents ingest the upper aquifer groundwater in the western
area of OU 5 for 70 years.  For ingestion of upper aquifer groundwater extracted along the
base of the bluff, the estimated  risks are largely due to arsenic and manganese which are
thought to naturally occur at elevated concentrations.
Elmendorf AFB OU 5 Record of Decision               3-20

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      Western

       Seeps
CORPS OF
ENGINEERS
 BLDG.
                       Groundwpter
   R.SK   o  j-     i.   /Exceeding
 ^pgic  Sediment  ^standards
,•  1 X 10-4     \       W   /
   RISK IN SOIL
     4.7 x 10-5
  Areos Considered for
  Remediol Action Legend:

         @  SOILS
                     Central
RISK IN SOIL
  9 x 10-5
                            Eastern
?SVO
                                                                        RISK IN PLUME
                                                                      ?   4 X 10-5
                                                                  ~'\
                                                    Surface
                                                     Water
                  Soils
        	  SEEP AREA

            GROUNDWATER PLUME
        [77] SURFACE WATER AND/OR SEDIMENTS
           (SNOWWELT AND BEAVER PONDS)

         O GROUNDWATER SAMPLE EXCEEDING STANDARD
                                                                                       (  /•
                                                                                       •\--/;
                                                                               1200
                                                                                  SCALE IN FEET
                             Figure 3-9. Human Health Risk in OU 5

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                            Table 3-5.  Human Health Risks
Media
Soil
Groundwater
Location
Western Area
Central Area
Western
Plume
Eastern
Plume
Cumulative Risk
4.7 x 10* ELCRa, HI < 1
9 x 10'5 ELCRa, HI < 1
1 x 104 ELCRa, HI = 3
4 x 10 5 ELCRb, HI < 1
Chemical(s) Driving the Risk
Arsenic, PAHs
Arsenic
Arsenic, gasoline, manganese, diesel
fuel, and benzene
Gasoline, TCE
a  Excess lifetime cancer risk, assumed future resident, 70 years of exposure by ingest ion.
b  Assumed future resident, 70 years if inhaling vapors while showering.

              The risk was calculated using assumptions regarding exposure pathways and
the time receptors, including humans and animals, were exposed to the contaminants.
Constant exposure was assumed over a lifetime.  This is a conservative approach that may
overestimate the actual risk.  Risk management decisions were made considering the
uncertainty in the assumptions  used in the risk assessment. At OU 5 the shallow
groundwater is not used and is not expected to be used  in the future, so existing risks and
potential risks are significantly less than the worst-case  risk.

              Environmental Risk Assessment (ERA)

              The ERA did not link particular contaminants to specific ecological impacts.
However, it identified potential risks to the environment and environmental receptors which
may have been affected by contaminants.  The  risk is calculated using an equivalency factor
and specific  risk numbers are not calculated. Detected  concentrations  are compared to
critical concentrations published in the literature.

              The ecological risk at the snowmelt pond was determined by comparing PCB
concentrations and associated TOC data with sediment quality criteria  for the protection of
aquatic life.  The  PCB standard is variable, depending on the TOC. The higher the TOC,
the more the PCBs are bound to the sediment,  and are  not available for uptake by receptors.
Elmeixiorf AFB OU 5 Record of Decision
3-22

-------
             The most specific correlation between environmental risk and particular
contamination is at the snowmelt pond.  Waterfowl such as dabblers are the only potential
receptors.  Sediment contaminated with PCBs at 1.16 mg/kg (the highest concentration
found) could pose a risk to ducks if they dig with their beaks in thie pond sediments:  Fish
are not found in the snowmelt pond.

             In general, animals could be exposed to contaminants through the soil gas they
breathe while burrowing, the plants they  eat, and the dermal contact they have with media
contaminated by fuels.  Plants could potentially be affected by contamination.  The RI/FS
determined that plant  stress exists in OU  5, but was probably not caused by identified
contaminants in the OU. The stress  is probably due to natural conditions. The ERA did not
discover  any impacted endangered species or endangered species habitat.

             Uncertainties Associated with the Risk Assessment

             Risk assessments involve calculations based on a number of factors, some of
which are uncertain.  The effects of  the assumptions and the uncertainty factors may not be
known.  Usually, the  effect is difficult to quantify numerically, so the effect is discussed
qualitatively.  Some of the major assumptions and uncertainty factors associated with the risk
assessment are the following:
             •      The assessment used EPA Region 10 default exposure parameters for
                    most calculations.  Some of these parameters are not realistic for a
                    subarctic climate (May overestimate risk).
             •      Existing concentrations are assumed to be the concentrations in the
                    future.   No reduction through natural degradation and attenuation over
                    time is r?.ken into account (May overestimate risk).
             •      No increase through additional contamination is assumed (May
                    underestimate risk).
             •      Potential degradation products of existing organic contaminants are  not
                    considered (May overestimate or underestimate risk).
ElmemJorf AFB OU 5 Record of Decision               3-23

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3.3          Established Final Contaminants of Concern (COCs) and Cleanup Levels

       .      Final COCs were developed from the results of the risk assessment and by
considering regulatory standards.  The final COCs are shown on Table "3-6 along with the
maximum detected result.  The basis for identifying the COC (risk or regulatory standard) is
identified.  The cleanup levels that will be achieved by the remedial action at OU 5 are  also
shown on Table 3-6.

3.4          Summary

             Actual or threatened releases of hazardous substances from OU 5, if not
addressed by implementing the response action selected  in this ROD, may present an
imminent and substantial endangerment to public health, welfare, or the environment.
Elmcndorf AFB OU 5 Record of Decision                3-24

-------
o
3,
>

3
o
D
8
                                                               Table 3-6
Final Contaminants  of Concern and  Cleanup Levels
Contaminant
Maximum Concentration
BasisforfOG
Clean Up Level
Basis for Clean Up Level
Groundwatcr . ' .'.'.. • ..
TCE
Benzene
TFH Diesel
TFH-Gas
52 /ig/L
8.5 ng/L
290 itg/L
700 ng/L
Contributes to a risk > 10'5
Contributes to a risk > 10'5
Contributes to a risk > 10'5
Contributes to a risk > 10s
5/ig/L
5/ig/L
10 ng/L
10 ftg/L
MCLa '• ••'
MCLa
Alaska Water Quality Standards'5
Alaska Water Quality Standardsb
Surface Water • • .
Sheen
TFH-Gas
JP-4
Sheens exists
400 ng/L
770 /zg/L
Water Quality Standard
Water Quality Standard
Water Quality Standard
No sheen
10 /xg/L
10 /zg/L
Alaska Water Duality Standardsb
Alaska Water Quality Standards1*
Alaska Water Quality Standards'5
Soil ...-'-. ;-'v
TFH-Diesel
1,160 mg/kg
Threat to groundwater
1,000 mg/kg
Alaska Cleanup .Matrix Level Cc
N>
L/i
       a  40 CFR Part 131, and 18 ACC Chapter 70.010a and d, 70.015 through 70.110, 18 AAC 80.070.


       b  18 AAC 70.020. Based on ecological risk (protective of aquatic resources).


       c  18 AAC 78.315.

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4.0           REMEDIAL ACTION OBJECTIVES, ALTERNATIVES, AND
              COMPARATIVE ANALYSIS

4.1           Remedial Action Objectives

              Specific remediation alternatives were developed and evaluated for the areas
with potential  risk and that exceeded the cleanup levels identified in Section 3.3. Specific
remedial action objectives are:
             •      Protect human health and the environment by preventing ingestion and
                    contact with contaminated groundwater by people and preventing
                    animal contact with contaminated seep water;
             •      Use treatment techniques whenever practicable;
             •      Implement a solution that is capable of managing impacts from
                    upgradient sources as the contaminants reach OU 5; and
             •      Implement a cost effective solution that can achieve the cleanup levels
                    for the final COCs.

4.2          Alternatives
             Beaver Pond Wetland Area and Snowmelt Pond Remedial Alternatives

             The sediment and surface water in the beaver pond wetland area have few
treatment options available that would be practical and feasible.

             Natural attenuation and institutional controls  would be the only response
actions that would be both effective and implementable for  the beaver pond wetland area.
Any attempt to  either contain, extract and treat ex situ, or treat surface water in situ would
negatively affect the wetlands area.  For example, physically removing visible sheens,
dredging sediments, or processing wetland water through a treatment facility would all upset
ecological balances, disturb the water flow, and/or violate potential ARARs that specify

Elmendorf AFB OU 5  Record of Decision                4-1

-------
minimal disturbance of wetlands.  It has been demonstrated in previous studies that the
beaver pond wetland area is a viable natural wetland that can remediate contaminants
entering into it.

             The constructed wetland will be made by partially filling the snowmelt pond so
that its average depth is 6 to 12 inches. This partial filling will isolate the PCBs in the
sediments.  The constructed (enhanced) wetland will expand the dimensions of the existing
snowmelt pond to treat low volumes of impacted water collected from groundwater seeps at
OU 5. Impacts to the existing snowmelt pond area will be minimized by the use of sediment
nets.  Mitigation will be accomplished by increasing the area of the snowmelt pond and by
the planting of additional wetland vegetation.

             The remedial alternative for the beaver pond wetlands is appropriate if the
following is true:
              1.     The beaver pond wetland continues to actively remediate groundwater
                    that discharges into the pond.
              2.     Concentrations of the COCs found at OU 5 today will not increase in
                    the future due to upgradient impacts.
             The second assumption deals with the migration of contaminants from
upgradient sources.

             Impacts at OU 5 from upgradient sources were evaluated in a three
dimensional flow and transport model.  The purpose of the model was to predict the future
concentrations of benzene and TCE in OU 5.  These two compounds are the primary risk
drivers at OU 5 and each has sources upgradient of OU 5.  Figures 4-1 and 4-2 show
benzene concentrations across Elmendorf AFB currently and in 10  years.  Figures 4-3 and
4-4 show TCE concentrations currently and  in 10 years over the same geographical area.
These figures show that the concentrations of benzene and TCE in  the groundwater that come
from upgradient sources are  predicted  to decrease in OU 5  over time.

Elmendorf AFB OU 5 Record of Decision                4-2

-------
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-------
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                                                                             rcnNr, wr, i toe AT ION
                                                                      ..i-.. .- OCN/CNC CONCC'i'RAttOH
                     Figure 4-3.  Elmenciorf AFB Benzene  Concentrations at the Water Table (10 Years)

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         Elmendorf  AF'B
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                                                                                            .L..-       ,(,.,.^,2
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OUJUW-2P ',>.           49W1.02
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  ..-'' OU3MW-??
                                •         . ; >,*»* -T.. ^ *•  A  \   \
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                                 ?>«^ MWOJ    '-^.\ jX'x"''"'^   • "'   **:•"•' ^•*>
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           igure 4-4.   Elincudorr  AFB TCE Concentrations at (he Water Table (10 Years)

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              The concentration contours on the year 10 figures show lower concentrations
than in figures for earlier years; however, the areas affected appear larger than the plumes
shown on the current year figures.  Some of the increase in affected area is due to migration,
but the apparent increase in plume size is also due to the method used to develop the plume
contours. The current year plume contours were drawn by hand, interpreting the extent of
contamination based on the  distribution of concentrations.  The year 10 contours are
computer generated using the model output.  Data are plotted on a much tighter grid using
the model output.  Also the model interpolates data and projects migration from a source to a
model grid node.  These two factors associated  with the model make a plume look larger
than if drawn using professional experience and judgment.

              A sensitivity  analysis was run on the model  to determine if changes in the
model assumptions could result in a different conclusion.   For example,  if no natural
degradation of TCE occurs, could conditions possibly degrade at OU 5? The model was run
with no TCE degradation and the results show that, in the  5- to 10-year horizon, the
concentration of TCE increases and impacts OU 5. Thereafter, TCE concentrations will
decline.  This finding is not realistic because the TCE was released 10 to 20 years ago. If
there were no natural attenuation the concentrations of the  COCs would be higher at OU 5
than revealed by the RI.  Another sensitivity analysis run on the model was to determine the
effect on OU 5 if the source areas contribute contaminants for 30 years. With this change in
assumptions, the model predicted that conditions at OU 5 would not degrade in the future.
Concentrations of TCE would slowly attenuate over 15 to  20 years,  a longer period than if
sources ceased contributing  contaminants in 5 years.

              The model results show that the assumption that impacts will not increase at
OU 5  is reasonable.
Elmcndorf A KB OU 5 Record of Decision               4-7

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              Identification of Remedial Action Alternatives

              To identify a remedial action alternative that could best achieve the objectives,
ten media specific options were identified.  These options  included no action, excavation,
pumping, passive extraction, treatment (e.g., granular activated carbon), bioventing,
biological treatment, institutional controls, air sparging, and wetland treatment.  These
options were combined in the FS into 32 multimedia alternatives.   Each alternative was
evaluated against the first seven CERCLA evaluation criteria.  Though there are 32
alternatives, many are only slightly different from each other.  To  simplify the comparative
analysis, the 32 alternatives were grouped into four alternatives that represent the  primary
actions that could be taken.

              Except for the no action and natural attenuation alternatives, the cost of each
alternative includes 30 years of monitoring groundwater and surface water, including Ship
Creek, the beaver pond wetland area, and influent and effluent of treatment systems, for the
contaminants of concern. This monitoring assumption is worst case and includes  the cost for
a hypothetical monitoring program.  The actual monitoring program will be developed as
part of the design of the selected alternatives.  The actual  number of locations that will be
monitored could be less than the worst case hypothetical assumption and actual  costs would
probably be lower than those presented in this  ROD. However, any changes in costs would
affect all alternatives and would not affect the alternative selection process.  A 7% discount
rate was assumed in calculating present worth cost.  Any expense of using or acquiring land
not owned by the Air Force is not included in  the cost estimates.   The four alternatives are
as follows:
Elmendorf AFB Ob' 5 Record of Decision                4-8

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1. No Action

No Cost

              Evaluation of this alternative is required by CERCLA as a baseline reflecting
current conditions without any clean up.  This alternative is used for comparison with each
of the alternatives.  While natural processes should degrade and reduce the concentrations of
the chemicals of concern to acceptable levels, this alternative does not include any long-term
monitoring.  There  are no costs associated with this alternative. Time frame until cleanup
goals are achieved cannot be determined.

2. Natural Attenuation with Institutional Controls for Groundwater and Beaver Pond
Wetlands Area/Passive Extraction with a Constructed Wetland for Groundwater
Seeps/Isolation of Snowmelt  Pond Sediments/Excavation, Biopiling, and Backfilling for Soil

Estimated Capital Costs:      $0.8 million
Annual Cost:                $0.08 million
Present Worth Cost:         $1.6 million
Time to Complete Clean Up: 20 years
Discount Rate:              7%
Cost Accuracy:              -30 to  +50%

              Groundwater would be remediated by natural  processes that break down and
dilute contaminants. In addition, institutional controls in the form of deed restrictions would
prevent future use of the contaminated water.  The Air Force would continue to monitor
groundwater quality and would regularly update off-base land owners  of the monitoring
results.  If there is  any indication that contamination is getting worse, the remedial actions
would be  reevaluated and additional action would be taken if necessary.
Elniendorf AFB OU 5 Record of Decision                4-9

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              Seep water would be passively extracted by natural flow with passive
extraction wells and collection systems from the upper aquifer before it reaches the
groundwater seeps.  Thus, the groundwater seeps would be eliminated. The contaminated
water would be channeled to the snowmek pond where engineered wetlands would be
constructed.  Biological processes would remove most of the contaminants from the water.
The treated water would flow from the constructed wetlands into a drainage ditch.  Tests to
determine treatment effectiveness would be necessary.  The engineered wetland would also
isolate the snowmelt pond sediments.  This alternative would treat all the contaminated seep
water except the seep water flowing into beaver pond wetland area.  Treatment of those
groundwater seeps must rely on natural attenuation to avoid damaging the wetland habitat.

              About 1,500 cubic yards of soil would be excavated from both of the areas
with surface soil contamination (see Figure 3-9).  Much of this soil would have to be
removed to install the passive extraction wells.  The holes would be backfilled with treated
soil or clean soil.  The contaminated soil would be transported to the eastern end of the base
to the existing biopiling system.

              Biopiling involves supplying air and required nutrients to a soil pile to
maximize natural degradation.  Degradation of contaminants would be monitored to
document the breakdown  rate and confirm that  cleanup levels are being met.  The treated soil
would  be used on base for fill after cleanup  levels are achieved.  It would take approximately
4 months to remove the contaminants from the  excavated soil by biopiling.

3. Active Extraction for Groundwater and Groundwater Seeps/Natural Attenuation for
Beaver Pond Wetlands Area/Natural Degradation with Institutional Controls  for Soil/Isolation
for Snown-sk Pond Sediments

Capital Costs:               $2.5 million
Annual Cost:               $2.1 million
Present Worth Cost:         $28.4 millon

Elmendorf AFB OU 5 Record of Decision               4-10

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Time to Complete Clean Up: 30 years
Discount Rate:              7%
Cost Accuracy:             -30 to +50%

             Water would be pumped from the aquifer and near the groundwater seeps
through wells that would be installed.  The water would flow into an air stripper (system to
volatilize contaminants) where the contaminants would be transferred to the air.  The air
carrying the contaminants would then be filtered by an activated carbon system.  Activated
carbon would be disposed at an U.S. EPA-approved RCRA facility. Finally, the water
would be discharged into the aquifer at the base of the bluff.  Separate systems could be used
in different areas.  This system  would remove more water than passive extraction, which
allows it to treat both the groundwater seeps and the groundwater.

             Natural degradation would remediate the soil contamination and institutional
controls would restrict access by humans.

4. Air Sparging with Soil Vapor Extraction for Groundwater and Groundwater
Seeps/Natural Attenuation for Beaver Pond Wetland  Area/Bioventing for Soil/Isolation for
Snowmelt Pond Sediments

Capital Costs:               $2.9 million
Annual Cost:               $1.8 million
Present Worth Cost:        $24.8 million
Time to Complete Clean Up: 30 years
Discount Rate:              7%
Cost Accuracy:             -30 to +50%

             This system would volatilize the groundwater contaminants while they are  in
the  ground.  Compressed air would be  pumped into the  areas with contaminated groundwater
through wells that would be installed.   The  bubbling air would separate contaminants  from

Elmendorf AFB OU 5 ReconJ of Decision              4-11

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the groundwater by volatilizing them into the soil vapor. A soil vapor extraction system
would then remove the contaminant-carrying vapors from the soil, so that the contaminants
can be adsorbed by activated carbon. Finally, the activated carbon is disposed at an U.S.
EPA-approved RCRA facility.  Breakthroughs (leaks of contaminant-carrying air) are
possible in the lower bluff area and near the bluff face.  Tests to determine treatment
effectiveness would be needed.  The Air Force might need  to get permission from
landowners to install this system on privately owned land below the bluffs.

              Soil would be treated by bio venting.  This process would add oxygen into the
soil to enhance the growth of natural microbial populations that feed on the organic
contaminants. A blower would force air into contaminated soil via wells. Nitrogen and
phosphorous  could be added to stimulate bacterial growth and contaminant destruction.  Soil
sampling would be needed to ensure that cleanup levels  were being achieved. It is uncertain
how long it would take to clean up the contamination.  Bioventing may require pumping out
groundwater  to lower the water table near the  contaminants if the water table is too close to
the contaminated  soil.

4.3           Summary of Comparative Analysis of Alternatives

              The comparative analysis describes how each of the four alternatives meet the
CERCLA evaluation criteria relative to each other.  Because the beaver pond wetland area
and snowmelt pond remedial alternatives will be included in any selected alternative, the
comparative analysis focuses on areas which are not addressed by these remedies.

4.3.1         Threshold Criteria

              Overall Protection of Human  Health and the Environment. Alternative 4
would provide the greatest protection of human health and  the environment because
groundwater, groundwater seeps, and soil would all be actively treated to acceptable cleanup
levels.  Alternative 3  is slightly less protective since soil is not actively treated.

Elmendorf AFB OU 5 Record of Decision               4-12

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Environmental receptors would continue to be exposed to surface soil contamination until it
is remediated by natural degradation.

             Alternative 2 would provide nearly as much protection as Alternatives 3 and 4
by actively treating groundwater seeps and soil, the contamination most likely to impact
human health and the environment. Currently, there are no environmental or human
receptors of upper aquifer groundwater.  Institutional controls for groundwater in
Alternative 2 would ensure that people will not be exposed to upper aquifer groundwater in
the future.

             Alternative 1 would not be as protective because people and environmental
receptors would continue to be exposed to contaminated soils and groundwater seeps until
contaminants in these media degrade to acceptable levels.

             Natural processes would take longer to remediate the soil and, without
monitoring, the progress of the natural attenuation and accompanying reduction in risk could
not be assessed.  In addition, Alternative 1 leaves open the possibility that future base
personnel and residents  might use contaminated upper aquifer groundwater.

             Compliance with ARARs.  Compliance with ARARs would be achieved for
Alternatives 3 and 4 which actively treat contaminants  in all impacted media. The time to
achieve cleanup levels is uncertain but is predicted to be less than 15 years.  Alternatives 1
and 2 would comply with applicable cleanup  regulations for groundwater and would likely
achieve cleanup levels within 15 to 20 years, based on the groundwater model.

             Alternative  1, the no action alternative, would not comply  with ARARs for
soil.  In addition, without monitoring, there would be no way to determine when, or if,
cleanup levels had been achieved in either soil or groundwater.
ElnieivJorf AFB OU 5 Record of Decision               4-13

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4.3.2         Primary Balancing Criteria

              Long-Term Effectiveness and Permanence.  All alternatives could be
effective in the long term. The model predicts that natural attenuation would be effective and
will remediate to the cleanup levels.  Once cleanup levels are met, remediation will be
permanent.  None of the alternatives would be expected to produce toxic by-products.

              Reduction in Toxicity, Mobility, and Volume through Treatment.
Treatment for this criteria is assumed to mean processes other than those which would
naturally occur.   Alternative 4 would reduce  the volume of contaminants through treatment to
a greater degree than other alternatives because it would actively treat contaminated soil,
groundwater, and groundwater seeps.  Alternatives 2 and 3, both of which employ active
treatment on two media, would provide slightly less reduction through treatment.
Alternative 1, which would not actively treat any media,  would not meet this criteria.

              Short-Term Effectiveness.  Short-term effectiveness is primarily affected by
whether alternatives would reduce risk in the short term and the degree to which alternatives
can be implemented immediately without causing negative side effects on the environment.
Alternatives which actively treat water or restrict its use reduce risk faster than alternatives
which solely rely on natural attenuation.

              Alternatives that negatively impact the environment  during implementation are
not effective in the short term.  This is the case with remedial alternatives that affect the
beaver pond wetlands.   Pumping water from the pond or interception of groundwater that
feeds the wetland would ruin the existing natural  habitat.  For this reason, natural attenuation
is the selected remedy  for the wetlands.  Natural  attenuation is relatively effective in the
short term  since implementing natural attenuation  is the only alternative which causes no
impact to the wetland while providing monitoring necessary to be  sure cleanup levels are
being met.  The study  of the beaver pond wetlands showed that it  is  a healthy functioning
Elmendorf AFB OU 5 Record of Decision          .     4-14

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system, and is currently managing contaminants entering the wetland through groundwater
flow, by natural physical, chemical, and biological processes.

              Alternative 2 would be the most effective in the short term.  Groundwater use
restrictions and soil and seep treatment would immediately reduce risk to humans and the
environment.  Soil treatment could be completed within a year.

              Alternative 4 would be fairly effective in the short term.  Once implemented,
soil treatment could be completed  within a year and its active extraction of groundwater
could expedite contaminant removal compared to natural attenuation.  A treatability study for
bioventing would be necessary.  More important, to implement bioventing in shallow soil
below the bluff some of the shallow aquifer might have to be dewatered.  This would cause
short-term damage to wetland environment in the area.

              Similarly,  the short-term effectiveness of Alternative 3  would be reduced
because active extraction of groundwater would negatively affect the wetland environments.
In addition,  this alternative would  rely on natural attenuation of soil which would not reduce
the impact of soil contaminants on environmental receptors.

              Alternative 1 would be the least effective alternative in the short term because
it would not take immediate steps  to reduce risks and would require the longest time to
achieve cleanup levels.

              Implementability.  As discussed above, Alternatives 2, 3, and 4 would
require  treatability studies before they could be  implemented.  Alternative 2 also requires
access to non-Air Force property to construct a  wetland in the snowmelt pond.  Alternative 3
would be the most difficult to implement because treated water could not be easily discharged
into the shallow groundwater in the area below  the bluff.  Alternative 4's implementability
would also be limited by the need  to dispose of or regenerate activated carbon.   Alternative 2
would be simpler to implement than Alternative 3 and 4;  since the technology is not

ElmcnJorf AFB OU 5 Record of Decision                4-15

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complex, the treatment options do not involve discharges of large volumes of water, disposal
of captured contaminants, or other technical obstacles to implementation.  Alternative 1
would be the easiest alternative to implement since no actions are involved.

              Cost.  Estimated capital costs, and annual operational and maintenance (O&M)
cost, are shown in the description of alternatives.  The present worth is the capital and O&M
cost over a 30-year period using a discount rate of 7 percent.  The costs are accurate to
within -30% to  +50% of the actual  costs.  Alternative 1 has no cost while active alternatives
(Alternatives 3 and 4) have  the highest costs.  Alternative 2 has  a relatively moderate cost.

4.3.3         Modifying Criteria

              State Acceptance.  The State of Alaska concurs with the Air Force and U.S.
EPA in the selection of Alternative 2.

              Community Acceptance. Based on the comments received during the public
comment period, the public has no preference of alternatives.  Qne letter raised concern
about implementing alternatives on land not owned by the Air Force.  Locating the wetland
in the snowmelt pond is the current engineering concept because of its location and existing
water balance conditions.  There  is also the beneficial result of isolating the PCBs in the
sediment of the  pond if the  wetland is  built at this location.  Another comment described
using electromagnetic/radio  frequency  technology to treat soil.  The  technology described
would be a viable solution comparable to the alternatives with active treatment (Alternatives
3 and 4). These alternatives have high cost to benefit ratios (high cost for the  incremental
benefit). The third comment supported Alternative 2.
ElmeiKlorf AFB OU 5 Record of Decision               4-16

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5.0           SELECTED REMEDY


              The selected remedy is Alternative 2 because it best meets the nine CERCLA

criteria.  It protects human health and the environment and complies with ARARs.  It is

effective at reducing contamination both in the short term and long term, and is

implementable, cost-effective, and acceptable to the public and the State of Alaska.

Alternative 2 provides an appropriate level of treatment to reduce risks and comply with

ARARs. Other alternatives do not meet the CERCLA criteria as well as Alternative 2.

Alternatives 3 and 4 provide little additional environmental benefit, especially relative to risk

reduction in Alternative 2, which is the most cost effective of the four alternatives.


              Alternative 2 was selected because it best provides the  following specific

benefits at OU 5:
                    Existing habitat in the beaver pond wetlands area is preserved.  The
                    monitoring will ensure that the current health state of the wetlands is
                    being maintained and improved as contaminant concentration levels are
                    decreasing.

                    The habitat in the snowmelt pond will be improved from an open pond
                    to a vegetated wetlands system.  This alternative is consistent with the
                    city of Anchorage's land-use plan that calls for the snowmelt pond to
                    be a greenbelt preservation area.

                    The pathway for PCBs found in the snowmelt pond sediment is broken
                    by constructing the wetland in this off-base location.

                    The impacts from seep water are isolated, thus protecting wildlife and
                    plants.  Collecting the  water protects surface  water bodies.   This action
                    prevents the spread of contaminants on the land surface.

                    Shallow contaminated soil source areas potentially contributing
                    contaminants to ground water are removed.

                    Institutional controls will eliminate risk to human health by ensuring
                    that contaminated upper aquifer  groundwater  will not be  consumed by
                    people until cleanup  levels (MCLs for benzene and TCE, see Section
                    3.3) are met.
ElmenJorf AFB OU 5 Record of Decision                5-1

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                    The remedy is appropriate because fuel pipes are regularly maintained.
                    The pipelines and tanks are hydrostatically tested annually and pressure
                    tested under higher pressures triannually.
              Specific components of the selected remedy are illustrated in Figure 5-1 and
consist of the following:


              Groundwater
              (1)    Institutional controls on land use and water use restrictions will restrict
                    access to the contaminated groundwater throughout OU 5 until cleanup
                    levels listed in Table 3-6 have been achieved.

              (2)    Groundwater will be monitored to estimate the rate of natural
                    attenuation, to provide an early warning of potential off-site
                    contaminant migration, and to ensure protection of human health and
                    the environment.
              Seeps
              (1)  .  Seep water will be passively extracted from areas of contamination
                    along the western and central bluffs. The water will be drained to the
                    constructed wetland where enhanced natural chemical, physical and
                    biological processes will reduce contamination to below cleanup levels.
                    The location of the constructed wetland will be determined in the
                    Remedial Design phase.  If it is located at the snowmelt pond, the
                    recommended site, a layer of permeable material will be placed over
                    pond sediment.  Baffles would be installed to control the flow of water
                    and maintain retention time and native vegetation will be put in place to
                    help degrade contaminants.

              (2)    Water will be monitored  near the exit of the constructed wetland to
                    ensure that the wetland is reducing concentrations to below the Alaska
                    water quality standards specified in Table 3-6.

              (3)    Natural attenuation will be relied upon to treat seep and surface water
                    in the beaver pond wetland area.
Elmendorf AFB OU 5 Record of Decision                5-2

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     SOUTH
                        NOT TO SCALE
 T,
 C3
Vi
                                                                   Monitoring and
                                                               Natural Attenuation
                                                                 for Groundwater
NORTH
                                  Excavate Contaminated
                                     Soil and Biopile
        Deed Restrictions/
       Institutional Controls
      for Contaminated Areas
                                                                 Horizontal
                                                               Drain Wells
                                                                                       Contaminated
                                                                                       Groundwater
            Seeps Collected and Discharged to
        Constructed Wetland in Snowmelt Pond

             Isolate Impacted Sediment
               in Constructed Wetland
Monitoring and Natural Attenuation
        for Beaver Pond Wetlands
        Ship
        Creek
                                             Figure 5-1.  Selected Remedy

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              (4)    Water from the seeps and beaver pond wetland areas will be monitored
                     to estimate the rate of natural attenuation and make sure that
                     contamination does not  reach Ship Creek.
              Soil
              (1)     Approximately 3,000 cubic yards of contamination soil near the ground
                     surface will be excavated in the western and central areas and
                     transported to an on-base treatment facility. The treatment facility will
                     be selected in the Remedial Design phase; biopiling is currently being
                     considered.
              (2)     Soil removed from the areas of contamination will be replaced by
                     treated soil or clean fill from on base.
              (3)     Soil in the treatment facility will be monitored for contaminant
                     concentration reduction.  When the concentrations are below cleanup
                     levels, the soil will be removed and used as fill around the base.
              The remedy will be implemented after the Remedial Design has been
completed.  The Remedial Design is currently in progress.  It is expected that the remedy
will be implemented for 30 years, or until cleanup levels have been achieved. The actual
time frame for remediation is not known but the groundwater model predicts cleanup levels
will be achieved in 10 to 15 years.  A 30-year planning horizon specified in U.S. EPA
guidance documents is being used.  Monitoring data will be regularly reviewed to assess the
progress made by the selected remedy toward the  cleanup levels.  If problems are identified,
further remedial action will be considered.  The public, the State of Alaska, and  the U.S.
EPA will be consulted before further remedial actions are chosen.

              Because the remedy will result in hazardous substances remaining on-site
above health based levels, a review will be conducted within  five years after commencement
of remedial action. The review will ensure that the remedy continues to provide adequate
protection of human health and the environment.
Elmendorf AFB OU 5 Record of Decision                5-4

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5.1           Statutory Determinations

              The selected remedy satisfies the requirements under Section 121 of CERCLA
to:

              •     Protect human health and the environment;
              •     Comply with ARARs;
              •     Be cost effective; and
              •     Utilize permanent solutions and alternative treatment technologies to the
                    maximum extent practicable.

5.1.1         Protective of Human Health and the Environment

              The selected remedy is protective of human health and the environment. The
current points of exposure include surface soil, seeps, surface water, and sediment.
Treatment will eliminate contamination in surface soil and seeps.  An additional benefit of
constructing the wetland in the snowmelt pond is that doing so would protect environmental
receptors by isolating PCBs in the sediments.  Natural attenuation will treat the beaver pond
wetland area surface water. The Beaver Pond study showed natural attenuation would be
effective and any other treatment method would pose a significant threat of doing more harm
than good to the wetland environment.

              There are no direct current receptors  of groundwater in OU 5.  Institutional .
controls will eliminate the risk to human health by ensuring that contaminated upper aquifer
groundwater will not be consumed by people until cleanup  levels (MCLs for benzene and
TCE) are met. The time required to achieve MCLs is not known, but could be as short  as
10 to 15 years based on the groundwater model.  The three dimensional model of
contaminant flow at Elmendorf AFB showed that conditions are not expected to degrade  at
OU 5 from sources within the  OU and from sources upgradient. Over  time, conditions will
improve and the model  predicts that cleanup objectives can be met by natural attenuation

Elmendorf AFB OU 5 Record of Decision                5-5

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processes.  Therefore, the model further substantiates that the selected alternative is
protective of human health and the environment.    A remediation period of 10 to 15 years is
reasonable given current land use at the site.

5.1.2        Applicable or Relevant and Appropriate Requirements (ARARs)

             Chemical-Specific ARAR—Chemical-specific cleanup levels for OU 5 are
identified  in Table 5-1.  The Maximum Contaminant Levels (MCLs) established for drinking
water under State and Federal laws are relevant and appropriate to groundwater contaminants
of concern at OU 5 as a chemical-specific  regulation.  For petroleum contaminated soil that
will be removed and  remediated, it is relevant and appropriate to  apply soil cleanup  level C
from Table D of 18 Alaska Administrative Code (AAC) 78.315.

             Location-Specific ARARs—Requirements which must be met due to the
location of the contamination and remedial actions are  identified in Table 5-2.  For OU 5
there are location-specific  requirements for the wetland areas between the bluffs and Ship
Creek.  Current studies indicate that portions of OU 5  between the bluffs and Ship Creek
meet the legal criteria for waters of the United States under 33 CFR Part 328.3.  Although
formal permits are not required, the substantive requirements under the Clean Water Act
Section 404  are applicable.

             Action-Specific ARARs—The selected remedy will comply with those ARARs
applicable to construction of the wetlands and extraction system and to  the excavation of the
contaminated soil.  Complying with the substantive requirements of National Pollution
Discharge Elimination System (NPDES)  and Alaska wastewater provisions will be necessary
to allow water treated by the constructed wetlands to discharge into a drainage ditch
Action-specific  ARARs are shown in Tables 5-3 and 5-4.   Treated water discharged from
wetlands into Alaska surface waters will  be controlled  to ensure that the quality of the
receiving waters meets the organic  standards for fresh  water set forth under 18 AAC 70.020.
Groundwater and groundwater seeps located at OU 5 contain naturally occurring high

Elmendorf AFB OU 5 Record of Decision                5-6

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 g.
 o
 •n
'CD

 O
o
a
o
                                 Table 5-1


Chemical-Specific Applicable or Relevant and Appropriate Requirements
Contaminant
Maximum Concentration
Cleanup Level
Established by ARAR
••" .• '-•'• • " ':••• • ' '-.'. • • .: ' •::":''' '. .• " ". ..'•
•;;- :-..-.-. . • ; :- - •;• ; . T .; .••'-•--.. .•.:!" ' " . •:.
•••-.••".• ••••'•• '•• ''V'. '- •'.':••'•' '-•'•• -' '"jSSx .•-••:••'•' :• ';••- .-.'• -.:.;•"• "J
; ,:; -:'•-;-.; ".;.;. . . Source of Requirement : ; : -,'•;
Groundwater
TCE
Benzene
TFH Diesel
TFH-Gas
52 /tg/L
8.5 /xg/L
290 ligIL
700 ng/L
5/xg/L
5/ig/L
10 Mg/L
10/ig/L
MCLa
MCLa
Alaska Water Quality Standards'5
Alaska Water Quality Standardsb
Surface Water
Sheen
TFH-Gas
JP-4
Sheens exists
400 ng/L
770 /*g/L
No sheen
10 /zg/L
10 //g/L
Alaska Water Quality Standards'5
Alaska Water Quality Standards'5
Alaska Water Quality Standards'5
Soil
TFH-Diescl
l,160mg/kg
1 ,000 mg/kg
Alaska Cleanup Matrix Level Cc
       a 40 CFR Part 131, and 18 ACC Chapter 70.0lOa and d, 70.015 through 70.110. 18 AAC 80.070.


       b 18 AAC 70.020.


       c 18 AAC 78.315.

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                                  Table 5-2
                          Location-Specific ARARs
Statutory,
Regulatory Basis
Resource
Conservation and
Recovery Act
Clean Water Act,
Section 404
Citation
40 CFR Sec. 264.18
18 AAC Sec. 63.040
33 USC 1251 et seq. Sec. 404
40 CFR Pan 230
33 CFR Parts 320-330
Description
Prohibits or restricts siting of hazardous waste
management units in certain sensitive areas (100-
year floodplain, active seismic area, wetlands).
Prohibits discharge of dredged or fill material into
wetlands without a permit.
Elmendorf AFB OU 5 Record of Decision
5-8

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                                                                      Table 5-3
o.
a

s
o
  Action-Specific Federal ARARs
            Operable Unit 5
Elmendorf Air Force Base, Alaska
c.
o
—1
D
          Standard, Requirement, Criteria, or Limitation
             Citation
           Description
      Comments/
     Applicability
          Clean Water Act

          •    EPA-Administered Permit Programs:  The
               National  Pollutant Discharge Elimination
               System

          •    Criteria and Standards for the National
               Pollutant Discharge Elimination System
    33 USC Sec. 1251-1376

    40 CFR Part 122



    40 CFR Part 125
Requirements for the discharge of
pollutants from any point source into
waters of the U.S. (surface waters)

Provides discharge criteria, chemical
standards, and permit forms for
existing industrial operations.
Applicable if remedial
action requires outfall
discharge

Applicable to  remedial
actions which  cause
discharge to waters of
the U.S.
          Occupational Safety and Health Act of 1970

          •    Occupational Safety and Health Standards
              Safety and Health Regulations for  .
              Construction

              Safety and Health Standards for Federal
              Service Contracts
    29 USC Sec. 657 and 667

    29 CFR Part 1910


    29 CFR Part 1926


    29 CFR Part 1925
Sets standards for safety in the work
environment.

Sets standards for safety in the
construction work environment.

States that safety and health
standards are applicable to work
performed under Federal Service
Contracts.
Applicable to all
remedial actions
          Clean Air Act

          •    National Primary and Secondary Ambient Air
              Quality  Standards
    40 CFR Part 50
Establishes standards for ambient air
quality to protect public health and
welfare.

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i
g.
o
3,
>
3
o
8
o
a
             Table 5-4


Action-Specific State ARARs and TBCs

          Operable Unit 5

  Elmendorf Air Force Base, Alaska
Standard, Requirement, Criicria',>:pr
Limitation :
Alaska Air Quality Control Regulations
Alaska Wastewater Disposal Regulations
Alaska Water Quality Use Classes and Criteria
Citation
18 AACCh. 50
18 AAC 72.500 - 72.600
18 AAC 70.020
Description
Establishes emission standards for classes of air pollution sources.
Provides for disposal of nondomestic wastewater into or onto the land,
surface water, or groundwater.
Provides water quality standards for freshwater uses.

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background levels of inorganic substances.  In determining compliance with NPDES and
Alaska Wastewater provisions, additional treatment will not be required to reduce
concentration in the effluent below the background concentrations set forth in Table 5-5.

5.1.3         Cost Effectiveness

              The remedy is the most cost effective of the alternatives because it affords
overall effectiveness proportional to its costs.  The additional protection that can be achieved
by actively treating groundwater in Alternatives 3 and 4 provides only marginal increases in
protection of human health and the environment with a cost several times higher than the
selected remedy.

5.1.4         Utilization of Permanent Solutions and Alternative Treatment Technologies
              to the Maximum Extent Practicable

              The U.S. Air Force, the State of Alaska, and EPA have determined that the
selected remedy represents the maximum extent to which permanent solutions and treatment
technologies can be used in a cost-effective manner at OU 5. Of those alternatives that are
protective of human health and the environment and comply with ARARs, the U.S. Air
Force, the State of Alaska, and EPA have determined that the selected remedy provides the
best balance of tradeoffs in terms of long-term effectiveness and permanence, reduction in
toxicity, mobility, or volume achieved through treatment, short-term effectiveness,
implementability, cost (as discussed in the preceding section), and the statutory  preference
for treatment as a principal element and considering State and community acceptance.

              All alternatives would use readily available technologies and would be feasible
to construct.  Alternatives 1 and 2 would be readily implementable; they require no
additional remedial action beyond construction of an engineered wetland.  The technologies
involved in Alternatives 3 are effective and use treatment technologies, but are less
implementable due to environment impacts caused by  the alternatives.

Elmendorf AFB OU 5 Record of Decision                5-11

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                               Table 5-5
       Maximum Allowable Effluent Discharge Based on Background
                Concentrations of Metals in Groundwater
^•P4^ ; ' ,.. ..'. ;,.:,;: ..,' .^
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
-|^ii;li|i;Si^^noebtration
Sl:rSSSSmg'L) ,,-,.,,
0.05
0.1
0.01
0.005
0.05
0.2
0.5
30
0.005
0.2
0.1
0.01
0.2
0.5
Elmendorf AFB OU 5 Draft Record of Decision
5-12

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              The most decisive factors in the selection decision were long-term
effectiveness and implementability.  Alternative 2 provides the best option for cost effective
and practical remediation of OU 5, because the benzene and TCE concentrations will return
to background conditions in time.  Alternatives 3 and 4 would reduce the concentrations of
these compounds in the aquifer; however, given the fragile nature of the geochemical
environment,  Alternatives 3 and 4 present considerable risk of damaging the natural wetlands
in OU 5.  Active extraction and air sparging will affect the water chemistry and water
balance of the wetlands, most likely negatively impacting the habitat in the wetlands.

5.1.5         Preference for Treatment as a Principal Element

              The selected  remedy satisfies this statutory  preference by using a constructed
wetland to remediate seeps and by on-base treatment of contaminated soils. Because of the
substantial additional cost of actively treating groundwater, its potential negative effects on
OU 5 hydrology, and the fact that there are no current receptors of groundwater, institutional
controls and monitoring are a better way of addressing groundwater contamination than
active treatment.  Natural attenuation and isolation are used in areas where active treatment is
impractical.

5.2           Documentation of Significant Changes

              The selected  remedy was the preferred alternative presented in the proposed
plan.  No significant changes  have  been made.
ElmemJorf AFB OU 5 Record of Decision                5-13

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                     PART ffl. RESPONSIVENESS SUMMARY

             Public Input in the QU 5 Selected Remedy

             The primary avenues of public input have been through the Proposed Plan and
public comment period.  The Proposed Plan for OU 5 was issued to the public on 6 June
1994.  This began a public comment period that ended on 6 July 1994.  To encourage public
comment, the USAF inserted a pre-addressed, written comment form in distributed copies of
the Proposed Plan.  The comment forms were also distributed at the 23 June  1994 public
meeting, held at the Federal Building in Anchorage.

             The public meeting to receive comments on the Proposed Plan was attended by
26 people including nine community members.  Oral comments were received from two
people:  one representative from Physicians for Social Responsibility, and one citizen
representing himself. Following the public meeting, and prior to the conclusion of the public
comment period, written comments were submitted by four individuals.

             All comments received are documented in the administrative record file for the
site.   A transcript of the public meeting is available for public review at the site information
repositories. The repositories are located at the Bureau of Land Management's Alaska
Resources Library and the University of Alaska at Anchorage's Consortium Library.  Public
comments, relevant to OU 5 and/or the environmental restoration program at Elmendorf, are
presented below and have been paraphrased for greater clarity.  This ROD is based on the
documents in the Administrative Record and comments received from the public.

Response to ruoiic Comments

Public Comment 1:  There was a concern that biopile technology and intrinsic remediation
                     may not work in this climate.
Elmendorf AFB OU 5 Record of Decision               6-1

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USAF Response:      A study by Cold Regions Research Labs indicates that biopile
                      technology will work in this climate.  ADEC has observed a number
                      of bioremediation projects in the Anchorage area which have been
                      effective at remediating petroleum-contaminated sites.  Some
                      bioremediation projects in the Anchorage area have achieved ADEC
                      Alaska Cleanup Matrix Level  A cleanup standards for petroleum-
                      contaminated soils.  Level A cleanup standards require restoring the
                      formerly contaminated soil to  a point where the soil can be reused
                      without any restrictions, limitations, or potential harmful effects to
                      human health and the environment.

                      The Air Force  Center for Environmental Excellence and the EPA's
                      Kerr Laboratory are cooperatively conducting a treatability study to
                      validate intrinsic remediation at OU 5.  If the ongoing treatability
                      study does not  validate the feasibility of  intrinsic remediation, then a
                      more active remedial action will be implemented.

                      Also, a detailed intrinsic remediation study on the beaver pond
                      wetland area was done in 1993 to  determine if natural physical,
                      chemical, and biological processes destroy the contaminants and clean
                      up the environment. The study  at the beaver pond did show that
                      intrinsic remediation is working.  There  are high levels  of
                      contaminants at the back of the pond near where groundwater
                      discharges into the pond.  No contaminants  were detected in the water
                      leaving the pond.  The study concludes that microorganisms play a
                      cr:*1""1 role in  contamination breakdown and reduction.

                      To determine if a plume contaminated primarily with fuel products
                      and, in particular, benzene would  naturally degrade in this climate, a
                      mathematical model was used to estimate migration and breakdown of

Elmendorf AFB OU 5 Record of Decision               6-2

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                      contaminants.  The climate was considered in choosing appropriate
                      model parameters, and the model results showed effective reduction of
                      contamination through intrinsic remediation.  The proposed
                      alternatives also include monitoring.  If the monitoring shows that our
                      assumptions were not correct, the proposed alternative will be
                      reevaluated and,  if necessary, a more aggressive approach to clean up
                      will be taken.

Public Comment 2:   Is the Base suggesting alternatives before they are proven to work?

USAF Response:      The proposed plan addresses the primary components of the remedial
                      action;  specific techniques will be developed in  the remedial design.
                      The components  of the Proposed Plan (monitoring, wetland treatment,
                      soil treatment,  and restrictions on the use of groundwater) will meet
                      the remedial action objectives.  If a specific design feature such as
                      natural attenuation does not operate as predicted, the other remedial
                      actions discussed in the proposed plan are contingent alternatives that
                      can be  reevaluated in the future.

Public Comment 3:   A concern was raised that since the releases occurred up to 50 years
                      ago and contamination is still found, that intrinsic  remediation occurs
                      slowly.

USAF Response:      The tanks and leaks were not drained of fuel product and repaired
                      until a  few years ago.  There could have been a continuous fuel leak
                      for some liL..: -jnd data show the plumes have not migrated far in 50
                      years.  The limited migration suggests relatively quick and effective
                      natural attenuation.
Elmendorf AFB OU 5 Record of Decision                 6-3

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Public Comment 4:   Is the rate of plume migration currently being monitored?

USAF Response:     Yes.  The rate of migration is tracked and is well documented in a
                     remedial investigation report.  Data and the groundwater model show
                     that detectable contamination does not migrate far from the source.

Public Comment 5:   The USAF was asked to clarify whether intrinsic remediation means
                     groundwater quality is only being monitored.

USAF Response:     Yes.  There will be up to  19  monitoring wells in OU 5.  The
                     monitoring will be used to document that intrinsic remediation is
                     remediating groundwater and that there is no threat  to human health
                     and the environment.  If the monitoring data show that cleanup levels
                     are not being achieved,  additional remedial action may be needed and
                     would be coordinated through the U.S. EPA and ADEC.

Public Comment 6:   When will the plumes with contamination reach Ship Creek?

USAF Response:     On a site-wide basis, it  does not appear that contaminants will reach
                     and impact Ship Creek.  The model of groundwater flow and
                     contaminant transport showed that in the future contaminant
                     concentrations in groundwater will decline and that  Ship Creek  will
                     not be affected.

Public Comment 7:   A concern was raised about how remedial action will be affected if
                     Elmendorf AFB were ,^ -Jose.

USAF Response:     Before any property is conveyed outside the base, there are
                     procedures to make sure it's not contaminated.  Before property can
                     be legally  conveyed, all remedies necessary to  protect human health

Elmendorf AFB OU 5 Record of Decision               6-4

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                      and the environment must be in place.  In the event property is
                      conveyed, by law the United States must specifically retain the right
                      to enter the property for remediation purposes should additional
                      remediation activities be necessary.  When a base reaches the Base
                      Realignment and Closure Committee, and they have decided to close
                      that installation, one of the first major decisions is how to clean that
                      property up as fast as possible  to convey that property to the private
                      sector. At that time, more expensive alternatives that would expedite
                      remediation could be selected.  Therefore, if the base were to close,
                      remedial action would continue.

Public Comment 8:   Does the Proposed Plan consider the cumulative effects from the
                      combination of contaminants?

USAF Response:      Yes.  In the residential-use risk assessment scenario, the Air Force
                      looked at cumulative risk and made  decisions on that basis, despite the
                      fact that the risk assessment is  very conservative.  The greatest
                      potential risk is from using the shallow aquifer. That aquifer is not
                      being used at the Base, so the  likelihood of drinking water being
                      drawn from that aquifer is very unlikely.

Public Comment 9:   The Proposed Plan for Remedial Action for  Operable Unit 5 (OU 5)
                      includes a wetland planned on  property owned by the Alaska Railroad
                      Corporation.  The action could render the land permanently unusable.

USAF Response:      Elmendorf AFB will be working v.-l:l. ;he Alaska Railroad Corporation
                      to gain access to the snowmelt pond area beneath the OU 5 bluff area
                      where pipes and lift  stations will be located. The access agreement
                      will provide for monitoring for the duration of the remediation effort;
                      possibly up to 30 years.

Elmcndorf AFB OU 5 Record of Decision                6-5

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Public Comment 10: The comment was made that the remedial action should be
                     implemented cost effectively.

USAF Response:     Elmendorf AFB will implement the remedial response cost effectively,
                     remaining in compliance with all regulatory and engineering
                     requirements.

Public Comment 11: In situ soil remediation using electromagnetic/radio frequency
                     technology has been thoroughly tested and evaluated.  Could this
                     technique be used at OU 5?

USAF Response:     The preferred remedial action was  selected after a review of
                     technologies shown to be effective  at the time the  Feasibility Study
                     was conducted.   Contaminated soil is limited to small areas with
                     relatively low concentrations of the contaminants of concern.  Given
                     these conditions, and since the impacted soil is easily removed, in situ
                     methods of remediation did not have favorable scores in the evaluation
                     of alternatives.

Public Comment 12: The concern was raised that it  has  taken a long time for action at
                     OU5.

USAF Response:     The evaluation of impacts and  developing remedial alternatives for
                     OU 5 was conducted following approved  U.S. EPA guidance on
                     conducting Remedial Investigations and Feasibility Studies.  All work
                     and decision making was done according  u, Jvj schedule and
                     requirements in the Federal Facilities Agree n'»e.T;i.
Elmendorf AFB OU 5 Record of Decision                6-6

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Public Comment 13:  Is the lower aquifer contaminated?

USAF Response:     No, wells have been installed into the lower aquifer and analytical
                     data have shown that the aquifer is not impacted.

Public Comment 14:  Are contaminants migrating into Ship Creek and the Knik Arm?

USAF Response:     Ship Creek has been sampled and data have shown that it has not been
                     impacted.  Monitoring of Ship Creek indicates that no measurable
                     amounts of contaminants are migrating from OU 5 into Ship Creek
                     and the Knik Arm. Monitoring will continue to be conducted in the
                     future as part of the selected alternative.  If monitoring indicates that
                     Ship Creek could be impacted in the future, corrective action will be
                     taken in cooperation with the regulatory agencies.

Public Comment 15:  Will covering snowmelt pond sediment with a layer of gravel isolate
                     PCBs?

USAF Response:     PCBs adhere strongly to sediment and have a very low solubility.
                     The primary transport mechanism is through sediment transport.  By
                     covering the sediment with a layer of gravel, the transport mechanism
                     will no longer exist.  Because of the very low solubility of PCBs, no
                     detectable concentrations of PCBs are expected in the water overlying
                     the gravel.  The pond water  will be monitored.

Public Comment 16:  Will intrinsic remediation effectively work at OU 5?

USAF Response:     Intrinsic remediation has been an effective process at the base to date.
                     The Beaver Pond Study (RI/FS, Appendix R) showed that the beaver
                     pond wetland area  could effectively attenuate contaminants that  enter

Elmendorf AFB OU 5 Record of Decision               6-7

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                       it.  The contaminant plumes are relatively small and have not shown
                       signs of widespread migration.  The intrinsic remediation alternative
                       for ground water is preferred because it is presently working, is shown
                       to be effective, and is the most cost  effective alternative.  The
                       alternative was selected after evaluating all alternatives against the
                       nine U.S. EPA evaluation criteria, and the alternative was found to
                       comply with applicable, relevant, and appropriate requirements.
                       Groundwater and surface water will  be monitored. If the monitoring
                       data indicate that intrinsic remediation is riot functioning as predicted,
                       Elmendorf AFB will work with the regulatory agencies to take
                       corrective action.
Elmendorf AFB OU 5 Record of Decision                6-8

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           APPENDIX A




OU 5 ADMINISTRATIVE RECORD INDEX

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                 Appendix A




Index to OU 5 Documents in Administrative Record
Date Submitted
7/01/94
3/04/94
11/17/93
11/17/93
11/17/93
12/08/93
6/01/94
6/03/94
5/01/94
5/01/94
Document Number
017830-018519
031679-033304
025778-025778
025779-025779
025780-025780
025788-025788
040264
040265
040268-040283
040284-040321
(confidential)
A>:;::;-.;; Title/Mjiject r;.f i-
Management Plan, Operable Unit 5, Elmendorf Air
Force Base, Alaska
Operable Unit 5 Remedial Investigation/Feasibility
Study
Letter from USAF to U.S. EPA requesting comments
on OU 5 Draft RI/FS and identification of ARARs
Letter from USAF to U.S. EPA requesting comments
on OU 5 Draft RI/FS and identification of ARARs
Letter from USAF to Alaska Department of
Environmental Conservation requesting comments on
OU 5 Draft RI/FS and identification of ARARs
Letter from Alaska Department of Environmental
Conservation requesting 20 day extension for comments
on the Draft RI/FS
News release in the Anchorage Daily News announcing
public comment period and public meeting for the OU
5 Proposed Plan
News release in the Sourdough Sentinel announcing
public comment period and public meeting for the OU
5 Proposed Plan
Elmendorf Air Force Base, OU 5, The Proposed Plan
for Remedial Action
Mailing list: May 1994 OU 5 Proposed Plan Fact
Sheet
Author
EMO/Battelle/CH2M Hill
USAF-Elmendorf AFB
Sharon Stone,
USAF-3 SPTG/CEVR
Sharon Stone,
USAF-3 SPTG/CEVR
Sharon Stone,
USAF-3 STTG/CEVR
Jennifer Roberts,
Alaska Department of
Environmental Conservation
USAF-Elmendorf AFB
USAF-Elmendorf AFB
USAF-Elmendorf AFB
USAF-Elmendorf AFB

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                       Appendix A
Index to OU 5 Documents in Administrative Record (Continued)
Date Submitted
12/94
11/18/94
11/17/94
12/94
Document Number
Unassigned
Unassigned
Unassigned
Unassigned
Title/Subject
Transcript of Public Meeting Written Public Comments
State Comments OU 5 ROD
U.S. EPA Comments OU 5 ROD
Ground water Modeling Report
Author
USAF-Elmendorf AFB.
ADEC
U.S. EPA • .
Radian Corporation

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