EPA/ROD/R10-94/092
January 1995
EPA Superfund
Record of Decision:
Eielson Air Force Base,
Operable Unit 2, AK
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OU-2 Record of Decision
Eielson Air Force Base
CONTENTS
Acronyms... .... "'..."'..".' -............... ......... ............ ..... .................... .... ..xii
Page
Site Characteristics......... ..... ....... ....'........... .... :............. ...............7
5.1 Source Areas STIO and SS14. ....... ........... ............. ....................8
5.1.1 Soil Contamination.....'''''''..''.''.''.''..''.''''.''''....''.''''''''... 9
5 .1.2 Groundwater and Surface Water Contamination............. .... .. ..10
5.1.3 Source Area Hydrology... ....... ...................................... .11
Source Area STll........ .......... ................ .......... ....... .......... ....11
5.2.1 Soil Contamination..... ....................... ..... ........ ............. .11
5.2.2 Groundwater Contamination............ ............. ........... .... ....12
5.2.3 Source Area Hydrology...~................... ......................... .13
5.3 ' Source Areas ST13 and DP26.......................~..........................,13
5.3.1 Soil ContaInination..... .................... ................ ....... ~.... ..14
5.3.2 Groundwater ContaInination... .......... ............ .................. .15
5.3.3 Floating Fuel Contaminati9n............ ............ .................. ..16
5.3.4 Source Area Hydrology...... .... ........... ..... ....... .'............. ..16
Source Area STI8....... ............ ~............. ...................... ........ ..16
5.4.1 Soil Contamination. . . .. . . .. . . .. . .. . . .. . . . .. .. . .. . . . . .. . . .. . .. . . . .. . . . . . . .16
5.4.2 Groundwater Contamination... ....................................... ..17
5.4.3 Source Area Hydrology..... .,.."......:.......... ..................... .,.18
Source Area STI9.... .... .'........................... ............... ....~....... ..18
5.5.1 Soil Contamination... ..'. .,...... ... ... ...;. ......... ....... ............. .18
5.5.2 Groundwater Contamination............ .............................. ..19
5.5.3 Source Area Hydrology................... ,............................ .19
Source Area LF05........................ ......... .............................. :'.19
Source Area LF07.. . . .. . . .. . .. . . .. .. .. . .. .. .. . : .. . .. . .... . .. . . .. . . .. .. .. .. . . . .. . ..20
Source Area Fr08 . . . . .. . . .. . .. . . .. .. .. . .. . . .. . . .. . . .. . .. .. .. . .. . . . .. . '.. . . .. . . .. . ..20
Source Area SS 12 .. . . .. .. .. . .. .. .. .. .. . .. .. .. . .. . . . .. .. . .. . .. . .. .. .. .. . . . .. . . .. . ..20
Source Area STI5[[[ ..20
, Source Area STI6........... ...... ....... ..... .... ........... ....... .... ,......:. .20 '
Source Area ST17 ........... ............... ....... ........... ....... ......... .'... .21
, Source Areas SD21, SD22, SD23, and SD24..................... ............21
Source Area DP28. ........ ........ ........ ..... ... ........ ........ ........ ....... .21
Source Area DP29.. ........ ....................... ............................... .21
Source Areas SS30 and SS31 ................................................. ..22
Dec,ision
1.0
2.0
3.0
4.0
5.0
5.4
5.5
5.6
5.7
5.8
5.9
. 5.10
5.11
5.12
5.13
5.14
5.15
5.16
I,
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Summary.... ........ ........ .............. .......... .............. .......... ....... I
Site Name, Location, and Description........................................... 1
Site History and Enforcement Activities............. .............. .............2
Highlights of Community Participation............ ............................. 3
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6.0
7.0
'6.0
9.0
OU-2 Record of Decision
Eielson Air Force Base
5.17
5.18
5.19
5.20
5.21
5.22
Source Area D P40.... ..... [[[ ..22
Source Area S541.......... ......... ... ............ ......... ..... ........ ...... ...22
Source Area SS42[[[ ..23
Source Area SS47............... ................... ..'.................,......... ..23
Source Area WP60.............. .... ......................................... ... ...23
Source Area SS62.. .. .. .. .. . .. . ..... ... ... . . . . . . """ .. . . .. . ... . . . . . .. .. ... . .... .23
~
Summary of Site Risks.... ...,. ... ........ ........ .............. ............ ....... ..24
6.1 Human Health Risks........... "'''''''''''''''' '''''''''''''''''''''''''''''' ...24
6.1: 1 Identification of Contaminants of Concern.... ......... .. .. ...... .... .24
6.1.2 Exposure Assessment. ............ ....... ........ .... .......... ........ ..25
6 .1.3 Toxicity Assessment.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .29
6.1.4 Risk Characterization............... .. ......... ...... ~.... .. .... ....... ..35
6.1.5 ,Uncenainty............. ................................................ ...41
.6.2 Environmental Risks.'............ ............................... """'"'' ..... ..41
Description of Alternatives[[[ ...42
7.1. Remedial Action Objectives ... ..... .... . .... .. .. .... .. . . ... .... . .. . . .. .. .. . ... ...42
7.1.1 Source Areas STH and ST18 .. ....... ...... "'"",,,,,,, ............ ..42
7.1.2 Source Area ST19....... ..............................,..........~.. ~.. ..42
7.1.3 Source Areas ST10, SS14, ST13, and DP26.....................~...43
7.2. STlO and SS14 Remedial Alternatives ............... ............... ........ ...44
7.2.1 Alternative 1: ' No Action Alternative...................................45
7.2.2 Alternative 2: Limited Action Alternative ................ ...... .......45
7.2.3 Alternative 3: Bioventing Alternative. ..... ........... """"" .......46
1.2.4 Alternative 4: BioventinglSoil Vapor Extraction/Air Spargingt ,
Passive S1d1ruIrUagAlternative .........................................46
7.2.5 Alternative 5: Soil Excavation/Groundwater Treatment
Alternative[[[ """"'" ..47
7.3 ST13 and DP26 Remedial Alternatives .... ........................ .............48
7.3.1 Alternative 1: No, Action Alternative...................................48
7.3.2 Alternative 2: Limited Action Alternative.. ............ .. ... . .. ... . ...48 '
'7.3.3 Alternative 3: Bioventing Alternative................................ ..48
7.3.4 Alternative 4: BioventinglSoil Vapor Extraction! Air Spargingl
Active Skimming/Groundwater Treatment Alternative...............49
7.3.5 Alternative 5: Soil Excavation/Groundwater Treatment
Alternative.. .. ...... .... ..... ......... ........ ... . ... . ~ ...... . .. .. ... . .. .. .50
Summary of the Comp'arative Analysis of Alternatives............... .'." .50
8.1 Overall Protection of Human Health and the Environment.... .. .. .. .. .. . .. . .50
8.2 Compliance with ARARs................. ........ ................. ...............51
8.3 Long-Term Effectiveness andPermanence.....................................51
,8.4 ' Reduction of Toxicity, Mobility, or Volume Through Treatment ...........52
8.5 Short-Term Effectiveness............................ ......................,... ..52
8.6 Implementability.................. '" ...~.........,................ .'. ~............ .52
8.7 Cost.................. .......................... .................................... .53
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2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
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19
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21
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24
OU-2 Reccrd of Decision
Eielson Air Force Base
10.0 Statutory Determinations........ ........... ....................... .... ..... .... .....57
10.1 Protection of Human Health and the Environment.. ............ ..... .... .....57
10.2 Attainment of ARARs of EnvironmentaI Laws .... """'" ..... ...., .........58
10.2.1 Applicable or Relevant and Appropriate Requirements..............58
10.2.1.1 Action-Specific.... ..... ........ """""'" '''''''' .......58
1 0.2.1.2 Chemical-Specific. ........... ...... .... ...... ....... .......58
10.2.1:3 Location-Specific ...................... .................. ...60
10.2.2 Infonnation To-Be-Considered ........ """ ............... ...........60
10.3 Cost' Effectiveness........ ............. ....... ............ ..... ................... .60
10.4 Utilization of Pennanent Solutions and Alternative Treatment Technologies
to the Maximum Extent Practicable..............................................61
10.5 Preference for Treatment as a Principal Element.......................~.......62
11. 0 Explanation of Significant Differences................................ 63
12.0 References.................. ........... ........ ........~.... ...................... .... ..64
Responsiveness Summary... '"'''' 0'.......... '''''''''''''''''''' .................... ..... ..74
TABLES
STI0 and SS 14-Subsurface Soil Contaminants of Concern. . . .. .. .... . . . . . . . .. . ... . 9
STI0 and SSl4--Groundwater Contaminants of Concern """"""" .............10
BTEX Concentrations in STIO Roating Fuel Samp~es................................l0
ST11~Benzerie, 1,2-DCE, Total Lead, and Arsenic in Groundwater. ........... ..12
ST13-Subsurface Soil Concentrations of TPH, B1EX, and Lead ....... ~ ... .. .. ..14
ST13 and DP26-Groundwater Concentrations of TPH,.BTEX, and Lead........ 15
. STI8--Semivolatile Organic Contaminants of Concern in Surface Soils. . . . . . . . . . . .17
Contaminant of Concern Risk-Based Cutoff Values for BTEX ... ...... .. .. ... .. .. . .18
B1EX Analyses from Monitoring Well 19-02A.. ...... ....... ...... ... .............. ..19
Exposure Point Concentrations for STI0 and SS 14 Risk Assessment... .. . . . .. .. . .25
Exposure Point Concentrations for STII Risk Assessment... .. """""" . .. .. .. . .26
Exposure Point Concentrations for ST13 and DP26 Risk Assessment..... . .. .. .. . .27
Exposure Point Concentrations for ST18 Risk Assessment... .. """""" . .. .. .. . .28
Exposure Point Concentrations for: ST19 RiSk Assessment... . . . . .. . . .... . . . .. . . .. . .29
Summary of Human Exposure Pathways for Source Area STIO and SS 14....... .30
Summary of Human Exposure Pathways for Source Area ST11' . .. . ... ..... .. . . . . . .30
Summary of Human Exposure Pathways for Source Area ST13 and DP26...... ...31
Summary of Human Exposure Pathways for Source Area ST18 """"""""'" .31
Summary of Human Exposure Pathways for Source Area ST19 ................... .32
Toxicity Data Used for Risk Assessments .......... """'" .... .... """"'" ...... ..33
Summary of Cancer Risk and Hazard Index for the Reasonable Maximum
Exposure Case at STI O/SS 14............... ............... ..................~.. ..........37
Summary of Cancer Risk and Hazard Index for the Reasonable Maximum
Exposure Case at ST11.............. ................................. ................... ..37
Summary of Cancer Risk and Hazard Index for the Reasonable Maximum
Exposure Case at ST13IDP26 [[[ .38
Summary .of Cancer Risk and Hazard. Index for the Reasonable Maximum
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26
27
28
29
30
31
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OU-2 Reccrd of Decision
Eielson Air Force Base
Summary of Cancer Risk and Hazard Index for the Reasonable Maximum
Exposure Case at ST 19.. .. .. . .. . . .. . . ... . . . . .. . .... .. . '" . ... . . . . . .. . . . . . . . . . . . . . .. . . " . . .39
Chemicals of Concern by Media.....,.......... '''''''''''''' .... .......... ........... ....43
Remedial Action Objectives......... .... ..... .... .... ............. ............. ...... .....44
Final Remediation Goals ................ ............. ..... ........ ................... ... ..44
Relationship between ARARs and Remedial Alternatives... "'" . . . .. . . . . ... .. .. . .'. . .45
Com parison of Cleanup Alternatives using the Five Balancing Criteria.... . . . .... . .51
Cost of Remedial Alternatives................... ....................................... ..54
Chemical-Specific ARARs for Chemicals of Concern. "'" ..... ...... .......... .... ..59
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FIG URES
1
2
3
4
5
6'
7
Location Map of Eielson Air Force Base......... ......... ............................ .~67
Operable Unit 2 Source Areas... "..... .-....................... ........................ ..68
STIO and SS14 Location Map............................... ...... ~................". ...69
ST11 I..ocation Map ..~........ ......-[[[ ..70
ST13 and DP26 Location Map....................... ............................. ........71
ST18 I..ocation Map ........... ................................ .......... .,.'''''''..'''''. ..72
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OU-2 Record of Decision
Eie/son Air Force Base
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ACRONYMS
Alaska Administrative Code
Alaska Department of EnvironmentaJ Conservation
Air Force Base
applicable or relevant and appropriate requirement
aviation gasoline
Ambient Water Quality Criteria
baseline risk assessment
base supply well
benzene,'toluene, ethylbenzene, and xylene
chronic daily intake ' ,
Comprehensive Environmental Response, Compensation, and Liability Act
1,2-dichloroethylene '
2,2-bis(para-chlorophenyl)-1,1-dichloroethane
1, I-dichloro-2,2-bis(para-chlorophenyl)-ethyl~ne
dichlorodiphenyltrichloroethane
dense non-aqueous phase liquid
U.S. Environmental Protection Agency
F etkral Facility Agreement
Fairbanks North Star Borough
feasibility study
hazard index
Harding Lawson Associates
hazard quotient
Installation Restoration Program
, Jet Propulsion No- 4
Jet Propulsion No.8
light non-aqueous phase liquid
maximum contaminant level
maximum contaminant level goal
Multimedia Environmental Pollutant Assessment System
ririlligrams per kilogram
milligrams per liter
motor gasoline
National Contingency Plan
not detected
no further action
National Pollutant Discharge Elimination System
National Priorities List
Office of Solid Waste and Emergency Response
operable unit '
Operable Unit 2
polycyclic aromatic hydrocarbon
polychlorinated biphenyl
Pacific Northwest Laboratory
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OU-2 Record of Decision
£ie/son Air Force Base
ACRONYMS (continued)
petroleum oil and lubricant
remedial action objective
Resource Conservation and Recovery Act
reference dosage
remedial investigation
remedial investigation and feasibility study
record of decision
Science Applications International Corporation
Superfund AmendmEnts and Reauthorization Act
source evaluation report
slope factor
soil vapor extraction
Toxicity Characteristic ,Leaching Procedure
total organic halogens .
total'petroleum hydrocarbon
Technical Review Committee
micrograms per liter
underground storage tank
volatile organic compound
year
.
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OU-2 Record of Decision
£ielson Air FofC6 Base
Eielson Air Force Base
Operable Unit 2 and Other Areas
Record of Decision
Decision Summary
~
1.0
Site Name" Location, and Description
Eielson Air Force Base (AFB) covers an area of approximately 19,270 acres, and it is
located within the Fairbanks North Star Borough (FNSB) approximately 21 miles
southeast of Fairbanks and 10 miles southeast of the city of North Pole, Alaska, along the
Richardson Highway (Figure 1). Approximately 3,650 acres are improved or partially
improved with the remaining land encompassing forest, wetlands, lakes, 'and ponds. The
base is bounded 'on the east and south by Fort Wainwright, a U.S. Anny installation, and
on the west and north by private and public land. The base is isolated from major urban
areas with the adjacent public and private land zoned general use. The approximate
population of the FNSB, Fairbanks, and North Pole is 82,000, 32,000, and 1,600,
respectively. Other communities near Eielson AFB include Moose Creek, which abuts the
northern border of the base, and the Salcha area, which abuts the southern border of the
b~e. '
Eielson AFB ,is a major employer in the Fairbanks area. The base employs approximately
3,400 military personnel and 500 civilians. The total residential population of Eielson AFB
is 5,132. The total population (living and working on the base) is approximately 10,000.
Residential and occupational populations are primarily concentrated in the developed
portion of the base. '
The area is active with ongoing base functions, including work, school, and recreational
activities. The base contains three elementary schools and one junior-senior high school.
There is one child care center and one medical and dental clinic.
"
. The base is located in the Tanana River Valley. Most of the base has been constructed on
fill material. The developed portion of the base's topography is generally flat and
somewhat featureless with elevations averaging about 550 feet above mean sea leveL The
undeveloped east and northeast sides of the base are as high as 1,125 feet above mean sea
level. Two-thirds of the base is 'covered with soils containing discontinuous permafrost
Half of the potential agricultural soils are cwrently being used for recreation facilities,
ammunition storage areas, Arctic Survival Training School, and other Air Force
developments. Significant wildlife trequents EielsoD AFB. The base supports a variety of
recreation and hunting opportunities. There are no resident threatened or endangered
species on the base.
The developed portion of the base is underlain by a shallow, unconfmed aquifer ,
comprising of 200 to 300 feet of loose alluvial sands and gravel overlying relatively 10w-
permeability bedrock. The aquifer is characterized by high transmissivities and relatively
flat groundwater gradients. Although there are significant seasonal fluctuations,
groundwater is generally encountered at approximately 8 feet below grade. The
groundwater generally flows to the north-northwest with the direction of flow locally
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OU-2 Record of Decision
Eielson Air Force Base
influenced by sulface water bodies (e.g., Garrison Slough and Hardfill Lake) and
groundwater extraction from the base supply wells.
Groundwater is the only source of potable water at the base and in the communities near the
base. Potable water in the main base system is treated to remove iron and sulfide.
Groundwater is the principal source for various other industrial, domestic, agricultural, and
fire-fighting purposes. .'
.
2.0
Site History and Enforcement Activities
Eielson AFB was established in 1944, and military operations have continued to the
present The mission of Eielson AFB is to train and equip personnel for close air support
of ground troops in an arctic environment Eielson AFB operations include industrial
areas, aircraft maintenance and operations, an active runway and associated facilities, and
administrative offices, as well as residential and recreation facilities.
In canying out its defense mission, contamination of the soils .and groundwater at the base
has resulted from the storage and handling of fuels and solvents plus the operation of
landfills. Initially this contamination was evaluated under the U.S. Air Force Installation
Restoration Program (IRP)~ The four-phase IRP was initiated in 1982 with a Phase 1
record search to identify past disposal sites containing contaminants that may pose a hazard
to human health or the environment Under the IRP, the U.S. Air Force identified 64
potential areas of contamination at Eielson AFB. Potential source areas include old
landfills, storage and disposal areas, fueling system leaks, and spill areas.
Eielson AFB was listed on the National Priorities List (NFL) (54 Fed. Reg. 48184) on
November 21,1989, by the U.S. Environmental Protection Agency (EPA). This listing
designated the facility as a federal Superfund site subject to the remedial response
requirements of the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act
(SARA).
In May 1991, the U.S. Air Force, the State of Alaska, and EP A entered into a Federal
Facility Agreement (FFA) (EPA et al. 1991) which established the procedural framework
and schedule for developing, implementing, and monitoring CERCLA response actions.
Under the FFA, the potential source areas were each placed in one of six operable units,
based on similar contaminant and environmental characteristics, or were included for
evaluation under a source evaluation report
An additional goal of the FF A was to integrate U.S. Air Force's CERCLA response
obligations and Resource Conservation and Recovery Act (RCRA) corrective action
obligations. Thus, any remedial action implemented will be protective of human health and
the environment such that remediation of releases shall obviate the need for further
corrective action under RCRA (i.e., no further corrective action shall be required).
On December 7. 1980, Eielson AFB submitted an application to EP A to store hazardous
waste and became subject to the applicable RCRA standards of a storage facility. These
standards provide general operational requirements and closure standards when hazardous
waste storage activities end. Building 3424, which was identified in the initial U.S. Air
Force appliC3;tion as the hazardous waste storage facility. is included in this record of
decision (ROD) as part of CERCLA source area SS31 and is otherwise subject to the
RCRA closure requirements under 40 CFR ~ 265, Subpart G.
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OU-2 Record of Decision
Eielson Air Force Base
,
On June 15, 1988, the EPA and Eielson AFB signed a RCRA Federal Facility Compliance
Agreement, which required Eielson AFB to pursue RCRA closure at specific hazardous
waste management areas, including 1) the Building 3424 storage area - CERCLA source
area SS31 and 2) Building 6214 - CERCLA source area ST16. These hazardous waste
management areas are addressed in the ROD under CERCLA. .
Several sites addressed within this ROD were used to manage hazardous waste subject to
RCRA. RCRA gives EP A the authority to require waste management unit closure and
cleanup measures for facilities that manage hazardous waste. The intent, as provided in
this ROD, is to address the substantive closure requirements of these RCRA-regulated sites
under CERCLA This effort will minimize duplicative program actions while
accomplishing functionally equivalent protective standards. Although certain sites may
remain subject'to additional administrative RCRA closure requirements, the substantive
closure requirements of these sites are proposed to be accomplished solely under
CERCLA.
3.0
Highlights of Community Participation
Mter the sigriing of the FF A (EP A et al. 1991) with the State of Alaska and the EP A, and
the listing of Eielson AFB on the NPL, the U.S. Air Force began its Superfund cleanup
program. As part of this program, in accordance with CERCLA Sections Il3(k)(2)(B)(i-
v) and 117, an extensive community relations program was initiated to involve the
community in the decision-making process.
. . . .
The community reliitions staff interviewed 40 local residents and community Jeaders to
develop plans to keep residents informed about the cleanup activity at Eielson AFB.
Follow-up interviews and questionnaires of more than 100 residents help~d revise the
Community Relations Plan. An environmental cleanup newsletter was created and mailed
to anyone who wished to be on the mailing list Fact sheets were prepared on various
topics related to the cleanup operations. Several times a year articles that describe
significant cleanup events are released to the base newspaper Goldpanner, as well as the
Fairbanks Daily News Miner. All of these efforts are designed to involve the community in
the cleanup process through comments they make when using this information.
The remedial ~vestigationifeasibi1itystudy(RIlFS) (U.S. Air Force 1993a, 1993b, 1993c,
1993d) and Proposed Plan (U.S. Air Force 1993i) for Operable Unit 2 (OU2) of Eielson
AFB were released to the public in November 1993. These two documents were m~~e
available to the public in both the administrative record and an information repository
maintained at the Elmer E. Rasmusen Library at the University of Alaska, Fairbanks.
"
The public comment period on the Proposed Plan was held from November 8, 1993,
through December 7, 1993. This was extended until December 20, 1993, to compensate
for a typographic error which required advertising the coITettion to the'plan. A COITeCted
addendum sheet was subsequently distributed to Proposed Plan recipients who were on the
mailing list Comments received during that period are summarized in the Responsiveness
Summ~ of this ROD.
The Proposed Plan for OU2 was advertised twice in two local papers. The public comment
period and public meeting were advertised on November 12 in the Goldpanner base paper.
A 9-inch display ad that highlighted the cleanup efforts was placed in the North Pole
Independent on November5 and 12, and in the Fairbanks Daily News Miner on November
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OU-2 Record of DeciSion
Eielson Air Force Base
5, 15, and 16.m addition, more than 3,500 copies were added as an insen in the base
newspaper and delivered to every home in the Eielson AFB housing area. A news release
announcing'the Proposed Plan and public meeting was sent to all local news media (radio,
television, and newspapers) and'the story ran on the front page of the base newspaper.
The meeting was advertised on the base access cable channel and in the base information
bulletin as well as on at least one local area radio station. The base First Sergeants Group
(the senior enlisted leadership for each unit on base) was briefed on the plan and public
meeting to encourage their people to attend. Copies of the plan were delivered to various
information repositories, plus the North Pole City Hall.
A public meeting was held on November 17, 1993. At this meeting, representatives from
the U.S. Air Force, Alaska Deparqnent of Environmental Conservation (ADEC), and EP A
answered questions about problems at the sites and the remedial alternatives under
consideration. About 30 people attended.
.
A Technical Review Committee (TRC) was established in 1992 including three
representatives for the community (selected by local officials and the University of Alaska
Fairbanks Chancellor), industry representatives, and environmental agency representatives,
and in November 1993, a localenviro~ental interest group was invited to participate.
The Proposed Plan was presented to the TRC on November 16,1993. At this meeting,
representatives from the U.S. Air Force, ADEC, and EPA responded to questions from an
audience representing the University of Alaska, the city of North Pole, and various State
and federal agencies.
Public comments in response to the Proposed Plan and public meeting ranged from solid
support of the plan as the best compromise among cleanup options to mild opposition
against several of the no further action proposals. A few residents wanted more
excavation,. but none wanted to delay the process. Treating the source of continuing
contamination (fuel-saturated soil) was supported as a good way to proceed at OU2, and
some suggested the same methods should be applied at some of the fuel-contaminated SER
source areas as well, even though the risk was within the acceptable levels. The specific
comments and U.S Air Force responses are included in the Responsiveness Summary in
this ROD.
4.0
Scope and, Role 'of Operable Unit
As with many Superfund sites, the problems at Eielson AFB are complex. Thus, the FFA
(EP A et ale 1991) divided the potential source areas at Eielson AFB into six operable units
(OUs) and three source evaluation report (SER) groups based on cOmmon characteristics
and con~inants.' .
The grouping of potential source areas into OUs was based on similar source characteristics
or contaminants. The OUs are
OU 1 Petroleum, Oil, and Lubricant (POL) Contamination
OU 2 POL Contamination
OU 3 Solvent Contamination
OU 4 Land Disposal of Fuel Tank Sludge, Drums, and Asphalt
OU 5 Landfills
OU 6 Ski Lodge Well Contamination. ,
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OU-2 Reccfd of Decision
Eielscn Air Force Base
An interim action at OUIB was initiated in June 1992 to initiate removal of petroleum '
products floating on top of the water table. OUs 1 and 6 are in the remedy selection
process. OUs 3,4, and 5 are in the RI/FS stage.
Six source areas with petroleum contamination were designated under OU2:
.
STlO--E-2 POL Storage
STll--Fuel Saturated Area
ST13--E-4 Diesel Fuel Spill
SSI4--E-2 Railroad JP-4 Fuel Spill Area
ST18-0i1 Boiler Fuel Saturated Area
STI9--JP-4 Fuel Spill.
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4
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A seventh source area, the DP26--E-I0 Fuel Tank Sludge Burial Site, was added to OU2
because of its geographical proximity, similar characteristics, and overlapping groundwater
contamination with source area ST13- The source areas in OU2 are shown in Figure 2.
OU2 addresses sites contaminated by leaks and spills of fuels. - Soils contaminated with
petroleum products occur at or near the source of contamination. Contaminated subsurface
soil and groundwater occur in plumes on the top of a shallow groundwater table that
fluctuates seasonally. Most of the contamination is in subsurface soils and the shallow
groundwater. Much of the groundwater contamination is believed to migrate from the
smear zone because of fluctuations in the groundwater table, rather than infl.ltration from
precipitation. These sites pose a risk to human health and the environment becauSe of
ingestion, i,nhalation, and dennal contact with contaminated groundwater. Also, there is
the threat of further migratiqn of contaminants into the groundwater from contaminated
soils and petroleum' products floating on top of the water table. The purpose of this '
response is to prevent current or future exposure to the contaminated groundwater, to
reduce further contaminant migration into the groundwater, and to remediate groundwater.
. .
Thirty-one other source areas are being evaluated through the source evaluation process.
Based on the available infonnation, these areas were believed to have a low probability of
posing a significant risk to human health and the environment. Twenty-one of these source
areas do not pose an unacceptable risk to human health and the environment, and are,
therefore, recorded in this ROD for no further action.
, ,This group of SER sites was evaluated in a screening assessment to detennine if each
source poses a risk to human health or the environment. The screening of contaminants
compared the maximum concentration of each contaminant detected at the source area to a
risk-based concentration calculated using a conservative target risk, calculated based'on
'EP A standard default exposure factors assuming a residential scenario. The target risks
used for this conservative screening were chosen based on the lower end of the 104 to 10-6
risk range specified in the NCP. The assumption used is that if no single sample exceeds a
concentration representing a human health risk concern, total exposure to the contaminant
from the source area will not be of concern. Specifically, the area required no further
action if the maximum concentration detected was ~ 1()-6 cancer risk for water, ~ 10-7
cancer risk for soil, and ~ 0.1 hazard quotient.
,
In addition, soil contaminant concentrations were evaluated to determine the potential for
contributing to groundwater contamination. Soil screening levels for the soil-to-
groundwater pathway were determined based on fate and transport modeling to prevent
exceedances of drinking water standards in the groundwater directly downgradient of the
source area.
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. OU-2 Record of Decision.
£ielson Air Force Base
All of the sites were found to contain contaminants below screening levels (e.g., maximtim
. contaminant levels [MCLs], EPA Region 10 guidance) or the affected pathway was
incomplete; therefore, no further action was required. These 21 SER sites are .
. LF05--0Id Anny Landf1l1
. LF07--Test Landfill
. Ff08--Fire Training Area (past)
. . SS 12--JP-4 Fuel Spill, Building 2351
. STl5-Multiproduct Fuel Line
. STI6-MOGAS Fuel Line Spill
. STI7--Canol Pipeline Spill
.. SD21-Road Oiling-Quarry Road
. SD22-Road Oiling-Industrial Road
. SD23-Road Oiling-Manchu Road
. SD24-Road Oiling--Gravel Haul Road
. . DP28--Ay Ash Disposal Site
. DP29-Drum Burial Site
. SS3G--Polychlorinated Biphenyl (PCB) Storage Facility
. SS31-PCB Storage Facility
. DP40--Power Plant Sludge Pit
. SS41--Auto Hobby Shop (past)
. SS42-Miscellaneous Storage and Disposal Area
. SS47-Commissary Parking Lot Fuel Spill
. WP60--New Auto Hobby Shop
. SS62 -Garrison Stough.
The additional 1 0 SER sites are still undergo~g a screening evaluation.
. All of the source areas listed above have been evaluated under the U.S. Air Force IRP and
the CERCLA RIlFS process. The stUdies listed below document preliminary inv~tigations
for most of these sites:
.
1982 JRP Phase I Records Search (CH2M Hill 1982) .
1985 JRP Phase IT ConfmnationlQuantification Stage 1 Draft Report (Dames & Moore
1985)
1986 through 1988 IRP RIlFS of the Fuel Saturated Area (SAlC 1989)
1989 IRP FS of the Fuel Saturated Area, Initial Screening of Remedial Technologies
and Process Options (SAIC 1989) . .
1989 IRP FS of the Fuel Saturated Area, Development and Evaluation of Alternatives
(SAlC 1989) .' -.
19891RP RIlFS Stage 3, Volume n (HLA 1989)
1990 IRP RIlFS, Stage 4, Volumes I through V (HLA 1990)
1991 IRP RIlFS, Stage 4, Volumes vn through xvm (HLA 1991)
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Inaddi~on, the following studies were conducted only for the OU2 source areas:
. 1993 RIlFS Final OU2 RI Report (U.S. Air Force 1993a)
. 1993 RIlFS Final OU2 Baseline Risk Assessment (BLRA) (U.S. Air Force 1993c).
. 1993 RIlFS Final OU2 FS (U.S. Air Force 1993d).
J
The following stUdy was conducted for the SER source areas:
.
1993 Final SER, Phase 1 (U.S. Air Force 1993g)
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OU-2 Reccrd of Decision
Eielscn Air Force Base
A very brief history of each source area is provided in the following section.
5.0
Site Characteristics.
.
Contamination at the OU2 sites has been investigated in detail since 1986. Science
Applications International Corporation (SAIC 1989) conducted soil gas surveys and
collected and analyzed soils, sediments, surface water, and groundwater in 1986, 1987,
and 1988. CH2M Hill collected and analyzed soil, sediment, sunace water, and
groundwater samples in 1991 and 1992. The data collected by SAIC were used t9
determine temporal changes in groundwater contaminant concentrations and were the
source for most soils analyses at DP26. These data were not validated as completely as the
1991 and 1992 data sets. The analytical results are compiled in a U.S. Air Force repon
(1993b). Unless otherwise noted, all analytical data discussed in this ROD were collected
during the 1991 field season.
There is only one aquifer for the OU2 source areas. The uncoIifmed aquifer consists of
alluvial sands and gravels. It is 200 to 300 feet thick and overlies crystalline bedrock
(Birch Creek Schist). Within this unit, only the upper 60 to 90 feet were characterized
during this investigation. The aquifer was found to be relatively homogeneous between
areas of investigation. The layering of materials indicates a greater horizontal than vertical
permeability.
The magnitude of the horizontal gradient was c31culated for the OU2 source areas. The
average horizontal gradient is approximately O;()()l foot/foot Data from a pumping test,
slug tests; and grain size analyses were used to estimate a hydraulic conductivity of
approximately 200 feet/day.
Water levels from nested wells at source areas STlO, STI8, and DP26 were compared to
provide information about vertical hydraulic gradients. The shallow wells generally have a
20-foot screen, beginning near the top of the aquifer, which is approximately 10 feet below
ground surface. The intermediate wells generally have a lO-foot screen, beginning at
approximately 30 feet below ground surface. Pressure head differences between the
shallow and intermediate w~lls were smaller th~ the potential elTor of the instrumen~.
Therefore, the venical gradient is negligible. . .
The direction of groundwater flow is to the north-northwest Locally, it is influenced by
Garrison Slough, Hardfill Lake, and pumpage of base water supply wells. The direction
of groundwater flow appears to be fairly constant year-round. Hardfill Lake is an old
gravel pit., excavated to a depth below the groundwater table. The lake is within the STIO
and SS14 source areas. .
...
Seasonal changes in water levels were interpreted using a precipitation hydrograph,
snowpack data, and temperature data, primarily collected in 1991 and 1992. In general, the
aquifer fluctuated uniformly across the site, indicating that similar hydrogeological
conditions exist in the upper 100 feet of the aquifer at all source areas. . Typically, the water
table reaches its minimum elevation in November. During this period, the discharge from
the aquifer to the Tanana River and its tributaries exceeds the recharge from precipitation.
In April, the water table typically rises dramatically, and a maximum is observed in the last
week: of May. The maximum water level is about 1 to 2 feet higher than the minimum
water level in November. This major recharge event coincides with the spring thaw, when
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OU-2 Record of Decision
£ielson Air Force Base
runoff from the snow melt is at a maximum. The water table drops relatively rapidly after
the end of May.
Two OU2 sites are adjacent to surface water bodies: Garrison Slough at STII and Hardfill
Lake at STlO. The interrelationship between groundwater and surface waters at these sites
is discussed within the site descriptions below.
Groundwater is the only source of potable water at Eielson AFB. This water is supplied by
three large-capacity wells of 1,000 to 2,000 gallons per minute capacity. The base water
supply wells are completed at depths averaging approximately 100 feet Seven wells are
designated to provide water to fight fires on the base and are designed for emergency use
only. They are plumbed to the water supply system. In addition to .the base water supply
wells, there are 41 private wells within a 3-mile radius of the base, most of which are.
located downgradient of the base (north-northwest of the base) in or near the community of .
Moose Creek (Figure 1) and in agricultural areas west of the base (HLA 1991). The city of
North Pole is served by a small public water supply system plus private wells.
5.1 Source Areas STIO (E-2 POL Storage) and SS14 (E-2 Railroad .IP-4
Spill Area) .
. .
Source areas STlO and SS 14 are discussed together in this ROD because they are located
close to each other, have similar types of contaminants, and the individual releases to
groundwater have created a joint groundwater contaminant plume.
The two sites are located in the southeastern developed portion of the base, along Quarry
Road (Figure3). STlO includes the E-2' POL storage area and Hardflll Lake, which lies,
200 feet northwest of the storage area. The storage area includes six 672,OOO-gallon,
aboveground fuel tanks. Secondary containment dikes sUlTound each of the tanks. A .
significant fuel spill within the Tank 6236 diked area was reported in 1967. Conflicting
reports exist as to whether or not the spilled fuel overtopped the dikes. The tanks presently
store JP-8 (arctic diesel). They have stored JP-4 and leaded fuels in the past Oil sheens
were observed on the surface of Hardfill Lake every spring and summer from at least 1978
to 1982 (CH2M Hill 1982).
SS14 is located immediately southwest of STI0. Until 1977, the area was used for rail
.delivery of fuel to the storage area. Currently, there are three truck refueling stands near
Building 6221 and unloading headers from the fuel pipelines. These headers are located
along the east side of the railroad line. The site is still actively used for offloading special
fuels. . .
Base Supply Well 14 (BSWI4) is located in Building 6224, approximately 240 feet
southwest of STI0. BSW 14 is one of four base water supply wells. It is used for a toilet,
sinks, and an emergency shower in Building 6224. Although routine testing indicates this
water is suitable for drinking, the well does not meet separation distances from a
contamination source as required by state of Alaska Drinking Water Standards. Bottled
drinking water is supplied at Building 6224. No other base water supply wells are Within
500 feet of STI0 or SSI4.
There are two RCRA-related areas that are geographically associated with STI0. By joint
agreement between the U.S. Air Force, EP A, and ADEC, these two areas are being
addressed in conjunction With STI0. One of these areas is a former drum storage area used
from 1976 through 1993. Approximately 450 drums were removed, with final sampling
and removal occurring in June 1993. The other area was used to store sandblasting grit
Six tanks were sandblasted to remove the old lead-based primer. The resulting material
~
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Eielson Air Force Base
Operable Unit 2 and Other Areas
Declaration of the Record of Decision
Site Name and Location
Operable Unit 2
Eielson Air Force Base, Alaska
Statement of Basis and Purpose .
This decision document presents the selected remedial actions and no action decisions for
Operable Unit 2 (OU2) at Eielson Air Force Base (AFB), Alaska, chosen in accordance
with the Comprehensive Environmental Response, Compensation, and liability Act
(CERCLA), as amended by the SuperjunLi Amendnumts and Reauthorization Act (SARA),
the May 1991 FedC;~ral Facility Agreement entered into by the Air Force, the U,S. .
Environmental Protection Agency (EPA), and the State of Alaska, and to the extent
practicable, the National Contingency Plan. 11ris document also presents the decision that
no further action is required for 21 other source areas at Eielson AFB. This decision is
based on the administrative record flie for this site.
The State of Alaska concurs with the selected remedies and the no action decisions.
Assessment of the Sites in Operable Unit 2 and Other Areas
Operable Unit 2 consists of seven source areas that have been combined because of
commonalty in containination that is mainly caused by leaks and spills of fuels.
The OU2 source areas are
STlO--E-2 Petroleum, Oil and Lubricant (POL) Storage
STI1--Fuel Saturated Area
ST13--E-4 Diesel Fuel Spill
SSI4--E-2 Railroad JP-4 Fuel Spill Area
STI8--0il Boiler Fuel Saturated Area
STI9--JP-4 Fuel Line Spill
DP26--E-10 Fuel Tank Sl~dge Burial Site.
Three of the sites (STl1, ST18, and ST19) will receive no further remedial action because
they present little risk to human health and the environment No feasibility study (FS) was
conducted for these three sites. However, the groundwater at these sites will continue to be
monitored as part of the Sitewide Program to conftnn the results of the remedial
inveStigation (RI). Four sites (STIO, SS14, ST13, and DP26) will be remediated.
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In addition, 21 areas previously identified as potential sources of contamination will receive
no further action because, based on existing information, they do not present an
unacceptable risk to human health and the environment A description of these areas is
included in the Phase 1 source evaluation report (SER). Data from these sites were
compared to screening criteria (e.g., maximum contaminant levels [MCLs], EPA Region
10 guidance) to evaluate the hazards. If contamination at a site was below the screening
level or the affected pathway was incomplete, no further action was ~uired. Source areas
that met these requirements are .
.
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OU-2 Recon:J of Decision
Eielson Air Force Base
LF07--Test Landfill
FT08--:Fire Training Area, Past
SS 12--JP-4 Fuel Spill, Building 2351
ST15-Multiproduct Fuel Line
STI6--MOGAS Fuel Line Spill
STI7--Canol Pipeline Spill
SD21--Road Oiling--Quarry Road
SD22--Road Oiling--Industrial Road
SD23--Road Oiling--Manchu Road
SD24-Road Oiling--Gravel Haul Road
DP28--Ay Ash Disposal Site
DP29-Drum Burial Site
SS30--Polychlorinated Biphenyls (PCB) Storage Facility
SS31-PCB Storage Facility .
DP40--Power Plant Sludge Pit
. SS41--Auto Hobby Shop, Past
SS42--Miscellaneous Storage and Disposal Area
SS47-Commissary Parking Lot Fuel Spill .
WP60--New Auto Hobby Shop
SS62 --Garrison Slough.
Actual or th~tened releases and exposure of people to hazardous substances from sites
STI0, SSI4, STI3, and DP26 within 002, if not addressed by implementing the response
action selected in this record of decision (ROD), may present an imminent and substantial
endangerment to public health, welfare, or the.environment.
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Description of the Selected Remedy
A FS was conducted for STlO, SS14, STl3, aI).d DP26. The sites were paired (STIO and
SSI4; ST13 and DP26)' and treated jointly in the FS becaUse of their physical proximity
and commiilgled groundwater contamination. Five remedial alternatives Were analyzed. for
each pair of sites. They are
Alternative I--No Action
Alternative 2-Limited Action
Alternative 3--Bioventing .
Alternative 4--Soil Venting/Air SpargingfPassive Skimming at STIO and SS14
Soil Venting/Air Sparging/Active Skimming/Groundwater Treannent at
. ST13 and DP26 ..
Alternative 5-Soil Excavation/Groundwater Treatment
Because of the variable levels and distribution of contamination, slightly different
alternatives were evaluated for these two pairs of sites.
Alternative 4 is the selected remedy for STIO, SSI4; STl3, and DP26. It addresses the
threats posed to hwnan health and the environment by the site by reducing the source of
groundwater contamination. This remedy is intended to achieve groundwater cleanup
through source removal. .
The major components of the selected remedy include
.
Install an active skimming system to remove fuel floating atop .the groundwater at ST13
and DP26 where the product is sufficiently mobile to be recoverable.
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OU-2 Record of Decision
Eielson Air Force Base
.
Install passive skimming systems to remove fuel floating atop the groundwater and to
prevent fuel from seeping into Hardfill Lake at STlO and SS14 where the product is
sufficiently mobile to be recoverable.
Install a bioventing and soil vapor extraction (SVE) system to remediate soil
contamination that poses a threat to groundwatex: through leaching. This system may
include air sparging within the upper part of the groundwater table and the smear zone
to volatilize and promote bioremediation of the contaminants. This entire system is also
anticipated to reduce fuel floating atop the groundwater.
.
.
Install groundwater extraction and treatment facilities in areas of highest groundwater
lead concentrations at ST13 and DP26. The physicaVchemical treatment of the
groundwater includes precipitation of metals and air stripping of volatile organic
compounds.
Monitor groundwater at ST19, STIO, SS14, ST13, and DP26 (0 evaluate contaminant.
levels and migration until remediation levels are achieved.
.
.
Monitor the distal end of the contaminant plume at ST13 and DP26 to evaluate if the
plume is expanding. Monitoring will continue for 5 years, at which time the need for
further monitoring will be reevaluated. Hydraulically contain the groundwater plume at
ST13 and DP26 by extracting groundwater from near the plume's distal end, if the
plume is expanding. The groundwater extracted from the hydraulic containment well
will be treated in the physicaVchemical system.
.
Notify the regulatory agencies of proposed dewatering activities, and evaluate their
potential for impacting areas of groundwater contamination.
.
Remove the drywell south of ST18 and test soils for contamination, if it can be located
and removed without damaging the existing structures. If the drywell cannot be
located, conduct confirmatory sampling.
Monitor the groundwater near STll, STI8, and selected SER sites, including SS31, to
verify that contaminant concentrations, if any, remain within acceptable screening
levels. Monitoring will continue for 5 years, at which time the need for further
moJ)itoring will be reevaluated. .
.
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Implement Institutional CQntrols to prevent exposure to contaminated groundwater. In
the event of base closure, any remaining contaminated sites will be addressed in
accordance with CERCLA Section 120.
Perform supplemental soil sampling during 1994 in the vicinity of Building 6214
(ST16) to confmn that no significant contamination remains. .
The remediation will be implemented with a phased approach, where ongoing monitoring
. will evaluate the performance of each technology before proceeding to the next phase of
cleanup. 1bis phased approach will allow the U.S. Air Force to use field data collected
during cleanup to get the best mix of technologies to meet cleanup objectives. Estimated
costs are conservative because it was aSsumed that all components of the system will be
required. If some of the ~omponents are not required, the actual costs may be significantly
lower. . .
.
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, OU.2 Record of Decision'
Eielson Air Force Base
Statutory Determination
The selected remedies are protective of human health and the environment, comply with
Federal and State requirements that are legally applicable or relevant and appropriate to the
, remedial actions, and are cost effective. The remedies utilize penn anent solutions and
alternative treatment (or resource recovery) technologies to the maximwn extent practicable
and satisfy the statutory preference for remedies that employ treatment that reduces toxicity,
mobility, or volume as a principal element.
Because these remedies will result in hazardous substances remaining onsite above health-
based levels,'reviews will be conducted at sites STlO, SS14, ST13, DP26, and ST19
within 5 years after commencement of remedial action to ensure that the remedy continues
to provide adequate protection of human health and the environment
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OU-2 ReClJro cifDecision
Eielscn Air Force Base
Signature. and Support Agency Acceptance of the Remedy for-
Operable Unit 2 and Other Areas, Eielson Air Force Base
G2tJ .
..~~~
mOMAS 'V.L. Mc'e L, Jr. \
Deputy Assistant Secretary of the Air Force
(Environment, Safety, and Occupational Health)
~ i'J J1~
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OU-2 Record of Decision
Eielson Air Force Base
Signature and Support Agency Acceptance' of the Remedy for
Operable Unit 2 and Other Areas, Eielson Air Force Base
. ~/~1Jt: /( /11 U-
LIAM D. McG~
Regional Administrator
Northern Regional Office.
Alaska Department of Environmental Conservation
~?/J9V
Dare ' ,
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OU-2 Record of Decision
. EielsOn Air Force Base
Signature and Support Agency Acceptance of the Remedy for
Operable Unit 2 and Other Areas, Eielson Air Force Base
!
,'(J{~ ..d, 71c?~c/l~
CHUCK-CLARKE
.t~egiona1 Administrator
1 Region 10
. U.S. Environmental Protection Agenc;y
7-:2/- 9'-)
. Date
. .
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OU-2 Record of Decision
Eielson Air Force Base
was put in drums and stored for about 1 year. Storage of these drums resulted in a RCRA
Notice of Violation in 1990. These drums have'been removed and disposed of through the
U .S- Air Force hazardous materials program. The presence of residual contamination at
both of these areas will be evaluated, as appropriate, as part of the CERCLA action for
STlO and SSI4.
Source areas STlO and SS14 both contain soil and groundwater contaminated by fuel spills
and leaks. In addition, there is a layer of fuel floating atop the groundwater at the sites.
The probable contaminant sources at STlO are leaks from the storage tanks and their
associated piping. The probable sources at SS14 are leaks from fuel lines and numerous
fuel spills that occurred during unloading and refueling operations along the railroad and
truck fuel transfer stations. '
5.1.1
STI0 and SS14 Soil Contamination
Surface, subsurface, and sediment soil samples were collected at STlO and SS14 during
1991 and 1992. . . .
Surface soil lead concentrations at STIO ranged from 7.8 to Fl4 mg/kg. Total petroleum
hydrocarbon (lPH) concentrations exceeded 100 mg/kg in all directed surface soil
samples. Seven of the 15 composite soil samples exceeded 100 mg/kg TPH.
TPH analyses were performed for all subsurface soil and sediment samples. Two samples
from each boring were analyzed for benzene, toluene, ethylbenzene, and xylene (BTEX)
compounds. Table llists the subsurface soil contaminants of concern.
TABLE 1. ST10 and SS14-Subsurface Soil Contaminants of Concern
Constituent Detection Detected/Analyzed Concentration Range Detected location of Maximum
limit (~g/kg) Concentration
(~g/kg) (Depth in feet)
rrPH 1700 - 50000 97/161 11,100 - 36,423,000 14S816-8.0
Benzene 20 - 690 18/65. 6 J - 9200 OJ 14S801-3.0
Ethylbenzene 5 - 660 34/65 15 - 54000 0 14S801-3.0
rr oluene 5 - 20 52/65 1 J - 33000 D 14S801-3.0
Xylenes 5 - 20 45/65 30 - 530,000 0 14S801-3.0
D-compound identified in an analysis at a secondary dilution factor
J-estimated value less than Contract Reauired Quantitation limit
At STlO, TPH contamination iIi excess of 1,000 mg/kg occurs beneath the tank fann and
extends northwest to Hardfill Lake. TPH concentrations in the borings collected near the
tank farm increase with depth and are greatest in the zone of groundwater table fluctuation
(referred to as the smear zone).
Assuming that the TPH contamination remaining at STI0 is the result of a significant fuel
spill within the bermed area, it appears that the fuel infiltrated downward to the
groundwater table, initially spread in all directions, then migrated downgradient towards
Hardfill Lake.
There appear to be two discrete locations of elevated TPH contamination at S514. One area
is located near the JP-4 fuel distribution headers at the southeast end of 5S14. The other
area is to the northwest, close to buried, abandoned motor gasoline (MOGAS) and diesel
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OU-2 Record of Decision
Eielson Air Force Base
fuel lines. Both locations have soil TPH concentrations greater than 35,000 mglkg in the
smear zone of the groundwater table. .
V olatile organic compounds were detected at SS 14 in the soil near the areas of TPH
contamination.
5.1.2 STIO and SS14 Groundwater and Surface Water Contamination, and
Floating Fuel
Table 2 lists the concentrations of contaminants detected in groundwater samples collected
at STI0 and SSI4.
The only volatile organic compound detected in surface waters (Hardfill Lake) was
benzene, at a concentration of 2 J.Lg/L in one sample. No semivolatile organic compounds,
pesticides, PCBs, or TPH were detected in surface waters. Metals' concentrations in
surface waters were similar to groundwater, except for total lead that had a maximum
concentration of 1.7 Jlg/L. . ..
TABLE 2. ST10 and SS14-Groundwater Contaminants of Concern
Constituent Detection Limit Detectedl Analyzed Concentration Range Detected Location of .
(Jig/L) (Jig/L) Maximum Concentratioli
"'PH 50 7/13 810 - 532,000 10MW08
Benzene 5 8/13 1 J - 1300 D 10MW01
rr oluene 5 6/13 2 J - 9500 D 10MW01
Irotal lead 3 12/14 1.9 B - 45.7 10MWO,
D-compound identified in an analysis at a secondary dilution factor
U-estimated value less than Contract Reauired Quantitation Limit
Floating fuel was detected in two monitoring wells in 1991. The floating fuel samples
from both wells were identified in 1991 as JP-4. Two samples of the floating fuel were
taken from one of these wells in 1992. The samples were analyzed in 1992 by Pacific
Northwest Laboratory (PNL) for BTEX. The results are in Table 3.
TABLE 3. BTEX Concentrations in ST10 Aoating Fuel Samples
Benzene Toluene Ethylbenzene Total Xylenes
Well (mg/L) (mg/L) (mg/L) (mg/L)
.10-8 266 6420 772 5144
10-8 271 6186 800 4902
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In 1992, additional characterization of the floating fuel ocCurred. Eighteen product probes
were installed at STI0 to detennine the extent of floating fuel. Results suggest that there
are two separate coalescing plumes,that intersect at Hardfill Lake. The source for one.
plume appears to be Tank 6238. The thickness of floating fuel in this plume appears to
fairly thin (<0.3 feet). The source for the other plume appears to be the truck fueling
station in S814. This plume appears to be much thicker (=:;1.48 feet). The distributio.n
headers at S8 14 were pressure tested in 1993, and the leaking pipes were replaced. The
total volume of floating product was estimated at 48,000 gallons (Appendix A of U.S. Air
Force 1993d). .
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OU.2 Record of Decision
Eielson Air Force Base
, Groundwater plumes of benzene, toluene, TPH, and total lead were identified during the
1991 field season. The highest benzene concentrations in shallow groundwater occur
beneath the tank fann and extend toward Hardfill Lake. It appears that groundwater
contaminated with benzene and toluene flows directly into Hardfill Lake. Shallow
groundwater contamination at concentrations exceeding the Safe Drinking Water Act
MCLs and action levels were identified for benzene, toluene, and lead. The highest TPH
concentrations occur in the same monitoring wells that contain floating product
Two sets of nested wells, wells completed at different depths in the aquifer, were installed
at STIO. The shallow wells are screened from 5 to 30 feet below the ground surface; the
intermediate wells are screened from 30 to 50 feet below the ground surface. The two
shallow wells had significant groundwater contamination (e.g., benzene at 1300 D and 430
D ~gIL); the only contaminant detected in the intennediate wells was benzene at 2 J J.Lg/L in
one. No other volatile and no semivolatile organic compounds were detected in either
well. No volatile or semivolatile organic compounds were detected in the sample collected
from BSW-14. BSW-14 is screened ~rom ~6 to 96 feet The well supplies water to
Building 6224. ' .
5.1.3 STIO and SS14 Source Area Hydrology
The groundwater flow direction at STIO and SS14 is to the northwest with a calculated
horizontal hydraulic gradient of 0.002 foot/foot. Staff gage readings from Hardfill Lake
indicate that lake waters are lower than the water table elevations at STIO, indicating that
groundwater discharges to the lake in this area. Groundwater in the area of the railroad
fueling facility flows to the northwest, then to the north and discharges into Hardfill Lake.
5.2 Source Area 'STH (Fuel Saturated Area)
Source area STII consists of subsurface diesel fuel contamination associated with one
building, Building 3224, situated along the southeastern side of Garrison Slough (Figure
4). The building was built before June 1956, and initially was used as the base bakery.
The bakery used diesel-fired ovens fueled by a 4-inch pipeline. The pipeline probably
came from several diesel tanks buried on the east side of Central Avenue. The tanks have
been removed. By 1981, the site had been converted to a dog training facility..
In 1975, a sheen was discovered atop the waters of Garrison Slough alongside ST11. An
i.pvestigation'discovered a petroleum diesel fuel, 'rermed around 1950, floating on .
, groundwater next to Building 3224. .
A cleanup action followed from 1977 to 1980. A 4-inch pipeline that still contained'some
diesel was removed in 1977. An oil-water separator was used in several excavated
trenches until 1980 for the removal of a floating fuel layer.
5.2.1
STll Soil Contamination
.
Samples were collected at STll in 1991 to identify the nature and extent of contamination
in surface an4 subsurface soils.
Lead was the only contaminant of concern detected in surface soil samples collected at
STIl. Lead concentrations in composite surface soil samples collected at STII 'ranged
from 8 to 95 mglkg. The locations of samples containing high lead concentrations are near
Central Avenue and are attributed to vehicle traffic.
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OU-2 Recon:J of Decision
Eielson Ai, Force Base
High TPH values were detected in soil samples at the groundwater smear zone. In most of
the soil borings, the highest TPH concentration OCCUlTed at the lowest sample depth, just
below the water table where values ranged from 1,260 to 23,500 mglkg. The highest TPH
concentrations were detected adjacent to Building 3224. The extent of contaminated soils
beneath Building 3224 is unknown. No elevated TPH values were detected north of
Garrison Slough. BTEX concentrations in the subsurface soil samples were all below ,the
levels of concern for protection of groundwater. The potential for the soil contamination to
act as a future source of groundwater contamination was evaluated in the aU2 RI (U.S. Air
Force 1993a), and the results of fate and transport modeling indicate that groundwater
contaminant concentrations are not expected to exceed regulatory levels.
Volatile organic compounds were not detected in most of the soil samples with elevated
TPH concentrations. B1EX, where detected, was at low concentrations, which suggests
that the diesel fuel has weathered since the spill or leak occurred, thus removing the lighter
fractions. Only the heavier fractions of the fuel appear to have remained in the soil.
The concentration of TPH contamination at 9 to 13 feet is consistent with the probable.
contaminant history at STII. The most likely source for the contamination was the buried
pipe that contained diesel fuel. Under the influence of gravity, the diesel would have
,spread out of the pipe and sunk to the top of the groundwater table. Here it would have
spread laterally atop the water, both up gradient and downgradient, fonning a floating fuel
layer.
5.2.2 8TH Groundwater Contamination
I
, '
I
I
I
I
I
Benzene, 1,2-dichloroethylene (DCE), total lead, and arsenic concentrations detected in
STll groundwater samples are Iisied in Table 4. No concentrations of volatile or
semivolatile organic compounds above the risk-based leveI$ of concern were identified in
groundwater samples collected at STll. TPH was detected in groundwater with a
maximum concentration of 90 J.1g/L. The TPH'soil contamination at the groundwater table
smear zone appears to have weathered sufficiently to remove volatile organic compounds
and water soluble semivolatile organic co~pounds from the groundwater.
TABLE 4. ST11-Benzene, 1,2-DCE, Total Lead, and Arsenic in Groundwater
Constituent Detection Limit Detected( Analyzed Concentration Range Detected, Location 01
, (~g/L) ,(~g/L) Maximum Concentration
Benzene 5 1/7 1 J 11 MW03
1,2-DCE 5 1n 1 J 11 MW07
Total lead 1 7/7 1.3 B - 4.5 '11 MW06
Arsenic 10 7n 1.1 B - 60 11MW04
J-estimated value less than Contract Required Quantitation Limit
B-analvte found in associated blank as well as in sample
Arsenic was detected at a concentration of 60 J.1g/L in one STll well during 1991. This
well has since been sampled twice, and both times the arsenic concentrations were below
the MCL of 50 J.1g/L (U.S. Air Force 1993g). Arsenic concentrations are variable and are
dependent upon seasonal groundwater levels and the natural oxidation state. The elevated
level of arsenic detected at STll is not assumed to be the result of contamination. In
addition, past activities at EieIson AFB are not expected to have. generated arsenic
contamination.
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Eielson Air Force Base
5.2.3
STII Source Area Hydrology
Staff gage measurements from Ganison Slough adjacent to STll show that surface water
elevations are usually higher than groundwater elevations. This indicates that in the vicinity
of STll, Garrison Slough loses water to the aquifer at all times except during spring thaw,
from about late April to late June. .
5.3 Source Areas ST13 (E-4 Diesel Fuel Spill) and DP26 (E-I0 Fuel Tank
Sludge Burial Site)
Source areas ST13 and DP26 are discussed together because they are located close to each
other, have similar types of contaminants, and the individual releases to groundwater have
created an overlapping groundwater contaminant plume.
Source area ST13 is located along the southeast end of the main taxiway west of Aightline
A venue (Figure 5). The area contains a fuel pump house (Building 1240), ten.
underground fuel storage tanks, five fuel outlets (1, 2, 3,4, and 4.5), and an area used in .
the past for filling and storing fuel bladders.
Source area DP26 is located directly across Flightline Avenue and includes a 420,000-
gallon aboveground storage tank (rank 300 [Structure 4482]) and ancillary piping, shallow
trenches used for the burial of sludge from fuel tank cleaning operations, an area where
fuel-saturated soil removed during replacement of Tank 300 in 1987 was placed, and truck
fill stands near Building 4480. Two underground tanks of JP-4 near Building 1240 were
reported leaking to ADEC in November 1990. The amount of fuel leaked is unknown.
Those tanks were part of the fuel hydrant system associated with Building 1240. The two
tanks were taken OUt of serVice in 1990. .
. -
Activities at both sites currently support the refueling of aircraft along the flightline. This
area has been used for the fueling of aircraft and other vehicles since Eielson AFB
operations began in World War II. The following fuels have been stored and dispensed
here: aviation gasoline (A VGAS), MOGAS, JP-4, and JP-8. ,JP-4.and JP-8 (arctic diesel)
are currently stored at these sites.
Contamination of soil and groundwater at ST13 resulted from the rupture or overfill of fuel
bladders filled ,in the area, and from leaks or spills from underground storage tanks and fuel
outlets in the area. The fuel bladders were used primarily to transport diesel fuel or
MOGAS to remote locations. The bladders were filled from outlets on the flightline, then
placed in a staging area within ST13 for transport. This pr~ was discontinued in
spring 1992. Two underground tanks of JP-4 near Building 1240 were reported leaking
, to Alaska Department of Environmental Conservation (ADEC) in November 1990. The
amount of fuel leaked is unknown. Those tanks were part of the fuel hydrant system
associated with Building 1240. The two tanks were taken out of service in 1990, and the
system components were purged of fuel. The underground fueling system'that connects
Tank 300 with the pump house and the five fuel outlets is scheduled for repla~ment in
1994. An estimated 12,000 cubic yards of soil will be excavated'during this replacement;
of this volume, 7,000 cubic yards are believed to be contaminated. These soils'are among
the most contaminated at the site, and they will be excavated and treated outside of the
CERCLA process as part of the construction project.
Cont~mination of soil and groundwater at DP26 probably resulted from leaks and spills
from Tank 300, its associated underground piping, and the truck fill stands. Tank 300 was
replaced in 1987. During the replacement of the tank, fuel-saturated soil was encountered
beneath the tank. The soil was removed and replaced with clean soil
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, OU-2 Record of Decision
Eielson Air Force Base
Weathered sludge from periodic fuel tank cleaning operations reportedly was buried in
shallow trenches. The sludge consisted of predominantly water with some rust, soil, and
fuel. Disposal of sludge in this manner occurred from 1955 until 1980. These burial areas
were not located during the remedial investigation.
No active base water supply wells are within 500 feet of ST13 or DP26. The main base
supply well (BSW-D) is 6,800 feet north of ST13.
5.3.1
ST13 and DP26 Soil Contamination
Samples were collected from surface soils and subsurface soil borings at ST13 dur,ing the
1991 field season. Soil samples were collected from DP26 during the 1986, 1987, and
1988 field seasons.
Lead, DDTs, TPH, and polycyclic aromatic hydrocarbons (PAHs) were detected in the
surface soils at STI3. The'maximwn lead concentration deteCted in surface soil samples
was 88.3 mglkg. The proximity of these sample locations to Flightline Avenue suggests
that the surface lead concentration is caused by vehicular exhaust from heavy traffic.
Four of the five ST13 surface soil samples exhibited elevated concentrations of 2,2-
bis(para-chlorophenyl)-I,I-dichloroethane (4,4-DDD), 1,I-dichloro-2,2-bis(para-
, chlorophenyl)-ethylene (4,4-DDE), and dichlorodiphenyltrichloroethane (4,4-DDT). The
maximum DDT concentration was 814 J1g1kg. DDT was not detected in background soil
samples. Again, the proximity of the sample location to Flightline Avenue suggests that
past base operations, including spraying for insect control along the roadway, may be
responsible for the peSticide residue detected in the sample.,
The maximum concentration of TPH in a composite surface soil sample is 814 mglkg.
TPH concentrations in the other two surface soil samples along Flightline Avenue were
also above 100 mg/kg. High TPH concentrations in the surface soil may be attributable to
vehicular traffic emissions or road maintenance activities. Similarly, P AHs were also
detected along Flightline Avenue. The semivolatile organic compounds are assumed to be
the products of uncompleted combustion of diesel fuel, or the residual components of road
maintenance materials.
Table 5 lists the concentrations of TPH, B1EX, and lead detected in s1,1bsurface soil
samples at ST13. Subsurface soil samples from DP26 were analyzed by SAlC (1989).
However, they were not included because the data were not validated as completely as the
1991 and 1992 data sets. Based on the subsurface soil investigation at STI3, there appear
to be two areas of elevated TPH contamination. One area is near a25,OOO-gallon ' '..
underground diesel storage tank. The other area identified is near Building 1240. The
highest TPH concentrations in subsurface soil samples occurred above the groundwater
table smear zone. '
I,
TABLE 5. ST13-Subsurface Soil Concentrations of TPH, BTEX, and Lead
Constituent Detection Limit Detected/Analyzed Concentration Range Detected Location of
(mg/kg) (mg/kg) Maximum Concentratior
(DeDth in feet)
irPH 1.9 - 50 41/55 6.7 - 31400 13SBC-12.7
Benzene 0.005 - 0.65 6/36 0.02 - 20 13SBC-12.7
IT oluene 0.005 - 0.65 10/36 0.02 - 220 13SBC-12.7
Lead 3/3 14.5 - 60.4 13SBC-07.5
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OU.2 Record of Decision
Eielson Air Force Base
The TPH contamination at the underground diesel storage tank resulted from either spills
associated with the fuel bladder fill operation, a leak in the storage tank, or contamination
from Tank 300, located immediately to the east across Flightline Avenue.
BTEX compounds were detected in the soil boring samples that also' had high TPH
concentrations. The contamination at one area may be the result of a fuel leak from
underground ,JP-4 storage tanks at Building 1240. The high BTEX concentrations
detected in soil boring samples (20 mg/kg benzene at 12.7 feet depth) may indicate a
recent source of contamination. As stated previously, a spill from Building 1240 was
reported to ADEC in 1990. '
5.3.2 ST13 and DP26 Groundwater Contamination
Table 6 lists the concentrations of TPH. BTEX, and total lead for groundwater samples
collected from ST13 and DP26 monitoring wells.
TABLE 6. 8T13 and DP26-Groundwater Concentrations .of TPH, BTEX, and Total Lead
Constituent Detection Limit Detectedl Ana Iyzed Concentration Range Detected Location of
(119/L) (1l9/L) Maximum Concentratior;
ITPH 50 3/5 100 - 101,000 13MW02
Benzene 5 18/22 1 J - 1400 26MW08
Ethylbenzene 5 13/22 1 J - 11 00 26MWO 1
Toluene 5 13/22 2 J - 4200 26MW08
Total lead 1 15/20 1.3 B - 795 26MW08
B-reported value is less than the Contract Required Quantitation Limit but greater than the Instrument
Detection Limit
J-estimated value less than Contract Reauired Quantitation Limit
The area of benzene contamination identified by an SAlC study in 1988 and sampling done
in the 1991 field season is I13ITOW in width and elongated in the direction of groundwater,
flow. Based ,on a comparison of the two studies, the benzene contamination appears to
have migrated approximately 600 feet in 3 years. The distal end of the benzene,
contaIn'inant plume was resampled in June ,1992. A comparison of the results from the
SAIC 1988 study and the 1991 and 1992 field seasons show that benzene concentrations
have declined significantly. The toluene and total lead 'contaminant plumes are centered in
the same location as the benzene plume.
.
There are a number of storage tanks and buried fuel pipelines located at ST13 and DP26 in
the area of highest groundwater contamination. Spills or leaks from these facilities are the
identified sources of past contamination.
The declirie in BlEX contamination noted previously suggests that either the source of
contamination is no longer active and the more mobile contaminants are dispersing, or
groundwater conditions are responsible for plume changes over time. The probable
source, Tank 300, was replaced in 1987. While no continuing releases are suspected, fuel
contamination in soil and floating fuel on the groundwater may be a continuing source for
contaminants dissolved in the groundwater.
The lead contamination probably resulted from old spills or leaks that occwred when leaded
fuels were used. The U.S. Air Force quit using leaded fuels in the mid-1970s.
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OU-2 Record of Decision
Eielson Air Force Base
5.3.3 ST13 and DP26 Floating Fuel Contamination
Floating fuel was identified and measured in 1991 in two groundwater monitoring wells.
CH2M Hill analyzed a sample of the floating fuel and identified it as either JP-4 or Jet A.
The BTEX concentration of floating fuel in one sample showed benzene at 363 mgIL,
toluene at 5,226 mgIL, ethylbenzene at 2,368 mgIL, and total xylenes at 13,975 mgIL. To
define the location and extent of the floating fuel at DP26, 11 product probes were installed
in 1992. The thickness of the floating fuel layer ranges between 0.06 feet and 1.13 feet
leading to an estimated volume of 7,000 gallons (U.S. Air Force 1993d). Tank 300 is the
likely source of the floating fuel product.
5.3.4 ST13 and DP26 Source Area Hydrology
The groundwater flow direction at ST13 and DP26 is to the north-northwest with a
calculated horizontal hydraulic gradient pf 0.0013 foot/fool Groundwater near Garrison
Slough appears to be,flowing towards and discharging to the slough. Extensive' '
dewatering activities during construction projects may have affected the groundwater
gradient and contaminant plumes. .
5.4 Source Area ST18 (Oil Boiler Fuel Saturated Area)
Source area ST18 is described as an old boiler plant (CH2M Hill 1982). The site presently
includes four buildings (Buildings 3405, 3409,3411, and 3386) (Figure 6) and is adjacent
to ST48, a source being addressed in QUI. Building 3405 is the old boiler plant that is ,
currently used for salvaging old vehicles before their use as targets. Buildings 3409 and
3411 contain backup diesel generators. Building 3386 is the Precision Measuring'
Equipment Laboratory where electronic gear is calibrated. ST18 also contains'two 25,000-
gallon storage tanks buried east of Building 3405. The tanks are currently filled by tanker
trucks with arctic diesel, and they supply the generators in Buildings 3409 and 341 L They
have been in use since 1948. Tank "tightness" testing in August 1993 and soils
information from the RI indicate that the tanks have leaked, and they will be removed in
cooperation with the state of Alaska under another compliance program.
Contamination was first reported at ST18 during the mid-1970s, when a series of 8-foot-
deep holes were excavated for installation of electrical wiriI)g. A floating hydrocarbon
layer was detected atop the water table in the excavations. The source of the contamination
was not identified, and there is no record of any remediation or repairs.
5.4.1
ST18 Soil Contamination
TPH was detected in all ST18 surface soil samples, with a maximum concentration of 976
mglkg. Lead was also detected in all surface soil samples with a maximum concentration
of 94.9 mglkg.
Several semivolatile organic compounds were detected in two ~omposiie surface soil
samples (Table 7). Both samples were obtained along the railroad'right-of-way on the
west side of STI8.
The P AHs present are characteristic of diesel exhaust, probably from long-term operation
of diesel engines. The most likely source is the Diesel Locomotive Repair Shop,
(Building' 3383), which is just north of the contamination. This shop is used for
locomotive repair, and the tuning of the large diesel power plants in locomotives is a
reasonable source for P AH contamination.
,.~
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Eie/son Air Force Base
TABLE 7. ST 18 Semivolatile Organic Contaminants of Concern in Surface Soils
Contaminant of Concern Detection Limit Detected/Analyzed Concentration Range Detected
(~g/kg) (~g/kg)
Anthracene 690 1/5 73 J
Benzo(a)anthracene 690 1/5 430 J
Benzo(a)pyrene 690 2/5 150 J - 550 J
Benzo(b)fluoranthene 690 2/5 88 J - 460 J
Benzo(g,h,i)perylene 690 2/5 430 J - 750
Benzo(k)fluoranthene 690 2/5 130 J - 480 J
Benzoic acid 3300 1/5 2300 J
Bis(2-ethylh exyl)phthala te 690 3/5 99 J - 170 J
Butyl benzyl phthalate 690 1/5 130 J
Chrysene 690 2/5 89 J - 550 .) .
Dibenzo( a,h)anthracene 690 2/5 . 130 J - 250J
Fluoranthene 690 1/5 640 J
Indeno(1,2,3-cd)pyrene 690 2/5 390 J - 620 J
n-Nitrosodiphenylamine 690 1/5 78 J
J-estimated value less than Contract Required Quantitation limit
The highest concentrations of TPH, maximum concentration of 30,898 mg/kg, were
identified in the vicinity of the underground diesel fuel $torage tanks. In general, TPH
concentrations in the vadose zone soils were less than 100 mglkg. The majority of the
contamination occurs in the groundwater table smear zone between 9 and 10.5 feet below
ground surface.
Volatile organic compounds (including B1EX) were not detected in the subsurface soil
samples above unacceptable risk levels as defined by EP A (l991a), implemented in the
BLRA (U.S. Air Force 1993c), and listed in Table 8. .
The source of the high concentrations of TPH is suspected to be leaks or spills of diesel
fuel from th~ underground storage tanks. The groundwater ~ble fluctuation is causing the
floatiI:1g fuel to spread througho~t the smear zone near the tanks. Fuel contamination .
remains in the soil in the smear zone.
5.4.2
ST18 Groundwater Contamination
.
Contaminant concentrations above screening risk assessment levels (Table 8) were not
detected in the groundwater samples at STI8. Benzene and toluene were not detected in
any groundwater samples. Trace concentrations of xylenes (8.0 Jlg/L) were detected at
one monitoring well.
Chlorinated solvents were detected at or below the Contract Required Quantitation limit
during both rounds of groundwater sampling. Trichloroethane and 1,2-DCE were detected
« 2.0 Jlg/L) in groundwater from all ST18 monitoring wells during the two rounds of
sampling in 1991. Soil gas analyses conducted by SAIC in 1988 revealed low
concentrations of halogenated hydrocarbons in the vicinity of Building 3423,
approximately 500 feet south of ST18 (SAIC 1989). A drywell in this vicinity is
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OU-2 Record of Decision
Eielson Air Force Base
TABLE 8. Contaminant 01 Concern Risk-Based Cutoff Values
. for BTEX
Contaminant 01 Soil Ingestion Soil to Groundwater
Concern (rng/kg) Groundwater (Jig/L)
(mg/kg)
Benzene 2.2 0.2 0.6
Ethylbenzene 2,740 80 159
Toluene 5,480 140 315
Xylenes 54,800 760 82.8
Soil concentrations for ingestion equate to a cancer risk of 1E-7
or a Hazard Quotient of 0.1.
Soil to groundwater concentrations are based on leaching to
groundwater (Appendix D of FS [U.S. Air Force 1993d]). The
concentrations equate to a cancer risk of 1 E-06 or a Hazard
Quotient of 0.1 for groundwater ingestion.
Groundwater. concentration equates to a cancer risk of 1 E-~ or a
Hazard Quotient of 0.1.
Calculations are in U.S Air Force (1993c) and are based on
IQuidance in EPA (1991a).
suspected to be the source of this contamination. It has not been located to date and
additional characterization is ongoing.
5.4.3
ST18 Source Area Hydrology.
The vertical gradient was measured via two different methods at ST18, and it is negligible.
5.5 Source Area ST19 (.JP-4 Fuel Spill)
Source area ST19 is located along Cargain Road next to a buried. concrete-lined utilidor
that is west of the road. The utilidor contains two jet fuel pipelines (Figure 7). A
snowplow broke a control valve in the late 1950s, and approximately 200.000 gallons of
JP-4 were spilled onto.the surface soils along the right-of-way. Evidence of vegetative
stress at the site was reported in 1984 (CH2M Hill 1982). .
5.5.1
ST19 Soil Contamination
Very low concentrations of l~d (maximum value of 17.3 mglkg) and TPH (maximum
value of 28.4 mglkg) were detected in surface soils at ST19.
lPH concentrations exceeding 100 mglkg in subsurface soil samples were lOcated in an
area along Cargain Road and extended into a Il31TOW area to the north. The area of
contamination identified to the north of Cargain Road coincided with a boggy low area. .
This suggests that the spill flowed into the low area.
Volatile organic compounds were detected in subsurface soil samples. Benzene was
detected with the highest concentration of 0.24 mglkg. Toluene. ethylbenzene, and
xylenes were detected at low concentrations in many of the soil borings within the area of
lPH contamination.
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. QU.2 Recotd o( Decision
Eielson Ai, Force Base
5.7 Source Area LF07 (Test Landfill)
Source area LF07 operated for several months in 1967. It primarily received household
waste with little or no industrial waste and is now covered with soil. There is no historical
evidence to suggest that the landfill contains high levels of contamination. A 199 ~ field
visit showed no evidence of stressed vegetation or surface debris: Based on its. shon
duration of use and the probability of little or no industrial waste, there is no evidence to
suggest that LF07 is a significant source of contamination.
5.8 Source Area FT08 (Fire Training Area rpastn
Source area Fr08 is an old gravel pit where fire-training exercises may have been
conducted from 1948 to 1955. The pit is filled with water and contains a partially
submerged B-29 bomber fuselage. The location of this area and the fact that another area.
was used for fire-training activities make the use of Fr08 as a fire-training area unlikely.
Field investigation of groundwater, sediment, soil, and surface water indicated that no
constituents were found above risk-based standards. In addition, there is no eviden~ to
suggest that the area was ever used for fire training exercises. .
5.9 Source Area SS12 UP-4 Fuel Spill. Building 2351)
In 1981,5,000 gallons of JP-4 fuel were accidentally discharged inside Building 2351.
Although the majority of the spill was contained within the building, it was estimated that
100 gallons flowed outside the building onto unpaved ground. Cleanup activities
recovered most of the fuel using absorbent pads.
Some contaminants would have evaporated, and the remainder would have moved through
subsurface soils into the groundwater where. they would have been dispersed and diluted to
below regulatory levels. Moreover, any contaminants remaining in the soil at the spill area
would have been removed by the grading, base-material placement, and paving that
subsequently OCCuITe9 around Building 2351.
There is no evidence to suggest that SS12 is a significant source of contamination.
S.10 Source Area ST15 (Multiproduct Fuel Line)
. . .
Two major fuel spills occurred from leaks. in subsurface pipelines. In 1970, 5,000 gallons
of automotive gasoline were spilled. In 1973, 5,000 gallons of JP-4 were spilled in the
same location. Some contaminants would have evaporated, and the remainder would have
moved through subsurface soils into the groundwater where they would have been' ..
dispersed and diluted to below regulatory levels. Site investigations were conducted in
1986 and 1987, and groundwater, sediment, soil, and surface water were all below
screening criteria.
. .
5.11 Source Area ST16 (MOGAS Fuel Line Spill)
In 1957,'approximately 5,000 gallons of gasoline were spilled. Contamination would have
likely evaporated or moved through subsurface soils into the groundwater where it would
have dispersed to below regulatory levels.
..-
In September 1986, a RCRA inspection at Building 6214 revealed approximately 265
improperly stored and labeled drums. By joint agreement among the U.S. Air Force, EP A,
and ADEC, this areas is being addressed as part of the adjacent CERCLA source' area
STI6. The drums probably contained paint and solvents. The drums were removed and
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OU-2 Record of Decision
Eielson Air Force Base
5.5.2 ST19 Groundwater Contamination
Benzene and toluene groundwater concentrations exceeded MCLs (fable 8) in only one
well at STI9. During 1992, this well had 11 ~gIL benzene and 1,900 ~g!L toluene.
Evaluation of contaminant data with time indicates that the benzene concentration in this
well has been decreasing monotonically since the first groundwater measurement by SAlC
in 1986. Table 9 displays the annual results of B1EX groundwater analyses from the
contaminated well.
TABLE 9- BTEX Analyses from Monitoring Well 19-02A. Values in Jlg/L.
Date 1986 1987 1988 1988 1991 1992
I (replicate)
Benzene 71 NA 35 NA 20 J 11
It oluene 1500 3600 6800 D 4100 1500 1900
Ethylbenzene NA 240 140 86 J 390 610.
Xylene 1100 2500 3200 D 2800 2300 4000
NA--not analyzed
D-compound identified in an analysis at a s~condary dilution factor
J-estimated value less than Contract Required Quan~itation Limit
. . .
The data indicate that benzene contamination is still decreasing monotonically. However,
ethylbenzene and xylene concentrations are increasing (both are still below MCLs), and the
toluene concentrations are relatively stable. Toluene remains above the MCL of
1,000 ~gIL. A fate and transport modeling an~ysis of the data is provided in
Section 5.6.4 of the RI (U.S. Air Force 1993a). The area of contaminated groundwater,
where benzene exceeds its MCL, is approximately 2 acres, and it is not expected to
increase. ... .
5.5.3 ST19 Source Area Hydrology
Groundwater flow direction is to the north~northwest at ST19 and is consistent with the
basewide groundwater flow direction. The average horizontal gradient across the area is
0.0011 foot/foot The gradient decreases to the north-northwest. Some factors that may be
affecting the gradient include local pennafrost and the fill material along Cargain Road and ..
along the pipeline corridor. .. . .
5.6 Source Area LF05 (Old Army ~
Source area LF05, which was used from 1956 to 1959, probably received general refuse
such as empty containers and drums, scrap materials, and small quantities of waste oils and
spent solvents. Site investigations and analysis of groundwater, sediment, soil, and
surface water indicate that concentrations of contam;n~nts in all samples~ with the exception
of one groundwater sample, were below risk-based criteria. One groundwater sample
contained lead four times higher than the action level of 15 ~gfL, but the analysis is
considered suspect because background samples also contained . lead at similar levels for the
sampling event. It appears that the wells were not purged properly. TIris well will
continue to be monitored in the site-wide groundwater monitoring program.
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OU-2 Rerord 0' Decision
cie/son Air Force 8856
properly disposed through the U.S. Air Force hazardous materials program. A site
inspection in August 1993 revealed small amounts of tar or asphalt deposits and several
small paint spills. There was no indication of spilled solvents.
Field investigations of groundwater and soil in~cate that no constituents were above
screening criteria. .
5.12 Source Area ST17 (Canol Pipeline Spill)
In the origin3.I IRP records search (CH2M Hill 1982), it was reported that the Canol
pipeline ruptured in 1957 and spilled approximately 20,000 gallons of diesel fuel. Field
investigations of groundwater and soil were conducted at STI7, but no fuel-related
contamination was found. Mter further review, it appears that the 1982 report incoITeCtly
attributed the spill to the Canol pipeline when it should have been assigned to the Haines
pipeline. Therefore, based on this infonnation and data from the field investigations, ST17
contains no source of contamination.
It appears that the actual spill area was located off base where the pipeline ~rosses the
Richardson Highway approximately 4 miles north of STI7.
5.13
Source Areas SD21. SD22. SD23. and SD24 (Road Oiling Sites)
Road oiling was used fQr dust control on unpaved roads (SD21, SD22, SD23, and SD24)
from 1950 until some time in the 1980s. Before 1978, roads were oiled with waste
petroleum products, including waste oils, contaminated fuels, and solvents. From 1978
until oiling was discontinued, waste engine oils and contaminated diesel fuel were used.
. . .
Some of the volatile contaminants evaporated during application or adhered to fine-grained
soil and was subsequently scattered non-unifonnly over a wide area by wind, vehicle
traffic, and routine road maintenance. Surface soils have been sampled in some adjacent
areas and contained no contaminants of concern above screening criteria. Many of the
unpaved road segments are now paved. There is no evidence to suggest that the roads are a
source of continuing contamination. .
5.14 Source Area DP28 (Fly Ash Disposal Site)
. .
. Source area DP28 is a fonner gravel boITOw pit used for disposal of fly ash generated by
the power plant from the early 19505 until 1977. Recent analyses of the fly ash total
elemental analysis and leaching tests (Extraction ~ure [EP] toxicity test and Toxic
Characteristic Leach Procedure fTCLP]) indicate that the material is not a hazardous. waste.
In addition, fly ash constituents do not exceed risk-based criteria for soils, except for
arsenic. The arsenic concentration (5 mglkg) is within the Eielson AFB soil background
range of 3 to 14 mglkg. Leaching tests show that the leachate would not exceed risk-based
criteria. The area has been graded and is covered with vegetation.
S.IS Source. Area DP29 (Drum Burial Site)
. .
Source area DP29 is a fonner gravel pit used to dispose of 55-gallon drums from 1965 to
1968. It is estimated that 400 to 500 drums, which were thought to have contained asphalt
emulsion, were placed in the gravel pit and covered with fill material. Most of the drums
were empty and some may have contained only residual amounts of engine oils and
industrial solvents. The gravel pit was later used for the storage of asphalt rubble. More
recently, some of the buried drums have been uncovered and removed. These drums were
found to be empty, crushed, and of poor integrity.
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OU-2 Record of Decision
£ielson Air Force Base
Site investigations and analyses of groundwater, soil, surface water, and sediment showed
no constituents were at concentrations above risk-based criteria.
5.16
Source Areas 5S30 and SS31 (PCB Storage Facilities)
Source areas SS30 and SS3l are former PCB storage facilities. Material stored at SS30 and
SS31 included undrained and empty transformer casings as well as PCB-contaminated
liquids and soils from cleanup of a PCB spill at another location. The PCB equipment and
waste material stored at SS30 and 5S3l were removed between 1982 and 1987 for off-.
base disposal. Other waste materials such as paint, paint remover, and solvents were also
stored at SS3l. .
In September 1986, a RCRA inspection at Building 3424 identified improperly stored and
labeled waste containers. By joint agreement among the U.S. Air Force, EPA, and ADEC,
. this area is being addressed as' part of CERCLA source area SS31.
There is no indication that S530 and 5S31 are a source of contamination based on the fact
that the buildings were properly curbed and diked to prevent releases and that there is no
evidence of spills inside or surrounding the buildings. The buildings are no longer used to
store PCB wastes and, therefore, are not a potential source of contamination.
A nearby groundwater monitoring well, just upgradient of SS31, contained elevated levels
of total organic halogens (fOX), oil and grease, and lead. While the contaminants are not
attributed to SS31, this well and others in the area will be monitored to determine the
source of contamination under the sitewide operable unit.
5.17 Source Area DP40 (Power Plant Sluf:lge Pjt)
In the initial IRP records search (CH2M Hill 1982), DP40 was reported to have been used
from the late 1950s until the late 1970s to dispose of sludge from air scrubbers in the .
power plant and residue from periodic cleaning of the power plant boiler. More recently, it
was discovered that DP40 has been active through 1993 and has reCeived the same waste as
in the past. The discharge was rerouted to the waste water treatment plant in 1993, but an
National Pollutant Discharge Elimination System (NPDES) permit is in effect for the waste
stream that will allow discharge to the pond, if needed. The pit is now filled with water.
The water contained a chalk-like substance, probably from mineral deposits from boiler
cleaning operations. The solids settle to the bottom of the pond, and in the past, these
materials were dredged out of the pond approximately every 2 years and placed in the base
landfill. . .
,
I
I.'
I
Analysis of the waste streams and sludge sample from the pond were supplied with the
NPDES permit application in 1993. The analyses showed that waste water constituents
were below risk-based criteria and the sludge contained high amounts of aluminum, iron,
calcium, barium, and manganese. These five elements are commonly present in soils and
aluminum, iron, and calcium are at levels found in Eielson AFB soils. Barium and
manganese exceed background concentrations by 20 and 3 times, respectively. None of
the concentrations exceeded screening criteria.
5.18 Source Area SS41 (Auto Hobby Shop rpastn
Source area SS41 was used by base personnel for repairing personal vehicles from the
1960s to 1982. Drums containing used oils and fuel were stored outside the shop, and
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Eielson Air Force Base
small quantities of industrial solvents were reportedly used. The drums were removed
between 1982 and 1986. The building was demolished, and the area regraded. .
Groundwater in this area contains benzene, apparently from another spill at ST13 and
DP26. This contamination is addressed as part of cleanup for ST13 and DP26. Site
investigations and analysis of groundwater and soil indicate that all constituents, except
benzene in the groundwater, are well below screening criteria. Benzene in the groundwater
will be treated as part of the ST13 and DP26 cleanup.
5.19 Source Area SS42 (Miscellaneous Storage and Disposal Area)
Source area SS42 was used during the 19605 for storage and disposal of miscellaneous
small equipment and construction equipment SS42 also has empty drUms that contained
waste oil, 1ubric.ants, and solvents. TIris area is now covered with trees and vegetation.
Site investigations and analysis of groundwater, sediment, soil, and surface water show
that only iron and manganese in groundwater exceeded screening criteria. High iron and
manganese are found througl1out the area, but these data are likely compromised because
of inclusion of sediJDent particles in the water sample during cellection. Background wells
sampled by the same group contained similar and'higher concentrations that were greatly
reduced with filtration.
5.20 Source Area SS47 (Commissary Parking Lot Fuel spiln
During a preconstruction soil investigation in 1987 for an addition to the Commissary,
some fuel-contaminated soil was found at a depth of about 9 feet near the center of the
paved parking lot The source of contamination is unknown; there are no known or
reported spills in this area. Field investigations of groundwater and soil in the center of the
parking lot showed that constituents were below screening criteria. TPH was detected in
soils mid-way between the ground surface and the water table at a 95% upper confidence
level of 5,255 mglkg. Above and below this h0IizOn, TPH averaged less than 100 mglkg.
Lead was detected in the groundwater at two wells located on the southern, upgradient part
of the parking lot, indicating the possibility of another source of contamination south of the
parking lot
5.21 Source Area WP60 (New Auto Hobby Shop)
Source area WP60 is used by base personnel for maintaining personal vehicles.'
Remodeling activities conducted in 1988 aild .1990 resulted in the removal of waste
disposal structures and contaminated soil. Base policies were and are in place for recycling
and disposing hazardous materials. Site investigations and analysis of groundwater;
sediment, soil, and surface water show that all constituents except benzo(k)fluoranthene in
soils (0.17 mglkg) were below screening criteria. The benzo(k)fluoranthene concentration
. corresponds to a 2 x 1O~ carcinogenic risk for ingestion of soil under a residential
scenario.
5.22 Source Area SS62 (Garrison Sioueh)
Garrison Slough~ which begins at the south end of Eielson AFB, flows north through the
developed portion of the base and into Moose Creek. The slough is not a domestic or
industrial water supply; however, the water is used to water family garden plots and for
recreational fishing. Garrison Slough was incorrectly listed as a contamination source.
Though tJ1e slough may have received contamination from sevenu different sources at the
base, it is not itself a potential source of contamination. The impacts to.Garrison Slough
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are being investigated whenever a source area has the potential for affecting the slough. In
addition, 'any residual contamination in the slough will be evaluated in the ongoing' site-
wide investigation.
6.0 . Summary of Site Risks
6.1 Human Health Risks
The baseline risk assessment (U.S. Air Force 1993c) provides. the basis for taking action
and indicates the exposUre path'ways that need to be addressed by the remedial actions. It
serves as the baseline indicating what risks could exist if no action were taken at the sites.
This section of the ROD reports the results of the baseline risk asseSsment conducted for
the OU2 sites.
. .
Contamination within the SER sites was analyzed by a conservative screening risk.
assessment that compared the maximum concentration of each contaminant c:ietected at the .
source area to a risk-based concentration calculated using a conservative target risk,
calculated based on EP A standard default exposure factors assuming a residential scenario.
The target risks used for this conservative screening were chosen based on the lower end of
the 1()4 to 10-6 risk range specified in the NCP.' The assumption used is that if no single
sample exceeds a concentration representing a human health risk concern, total exposure to
the contaminant from the source area will not be of concern. Specifically, the area required
no further action if the maximum concentration detected was ~ 10-6 cancer risk for water, ~
10-7 cancer risk for soil, and ~ 0.1 hazard quotient. .
None of contamination at these sites exceeded the screening levels, thus further risk
assessment was not necessary for the SER sites. .
6.1.1
Identification of Contaminants of Concern
Data collected during the RI were used to identify contaminants of concern at each OU2
site. Media sampled included groundwater, surface water, subsurface soils, surface soils,
and sediments.
The contaminantS of concern were identified based on the screening method suggested in
the supplemental guidance for Superfund Risk Assessments in EP A Region 10 (EP A
1991a). This method, called the ."risk -based screening approach," compares the maximum
. concentration levels of each chemical detected at each site to a risk-based screening' ..
concentration. The screening concentrations were calculated using a future residential
exposure scenario for the ingestion of soils and sediments, and the ingestion of water and
inhalation of its vapors during showering. .
Tables 10 through 14 list the contaminants of concern for eacb OU2 site, and the
concentrations for each input into the risk calculations. The concentrations listed for each
contaminant of concern are.either the maximum value or the 95-percent upper confidence
level on the mean concentration, whichever is smaller.
The analytical data used for all sites were collected during the 1991 field season, and are
listed in Appendix A of the RI (U.S. Air Force 1993b). The concentrations listed in the
tables in Section 5 provide a snmmary of these data. All water analyses and those soil and
sediment analyses that met or exceeded EP A Level ill were used.
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. Eie/son Air Force Base
TABLE 10. Exposure Point Concentrations for ST10 and SS14 Risk Assessment
Contaminant Surface Subsurface Sediment Ground Surface
01 Concern Soil Soil Water Water
(uo/ko) (uo/ko) (uo/ko) (uo/L) (uo/L)
!volatile Compounds
Benzene 1.30E+03 3.84E+02 1.00E+00
Ethvlbenzene 8.33E+01
h" oluene 2.03E+03
b
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£ielson Air Force Base
TABLE 11. Exposure Point Concentrations for'ST11 Risk
Assessment
Contaminant Surface Subsurface Ground
of Concern ,Soil Soil Water
(J,lg/kg) (J,lg/kg) (J,lg/l)
Volatiles
Benzene 1.00E+OO
Pesticides
4,4'-DDT 2. 72E+02
Metals
Arsenic 1.92E+04 1.46E+04 4.22E+01
Barium 2.05E+02
Beryllium 4.80E+02
Manganese 6.51 E+05 5.3E+05 1.98E+03
Thallium 6: 1 OE-01
system was used. The future industrial scenario assumed that water is provided by an
untreated shallow groundwater well within the site. '
In addition, a future residential land-use exposure scenario was calculated for each site.
This scenario assumed that a small family farm, with adults and children, is located atop the
site. Their water supply would be untreated groundwater from a well located within the
site.
For each source area and each exposure scenario, the following exposure pathways were
considered:
. ingestion of groundwater used as potable water supply
. inhalation of contaminants during groundwater use
. dermal contact with contaminants during groundwater use
. incidental ingestion of swface water '
. ingestion of fIsh
. dermal contact, with surface water
. incidental ingestion of sediments '
. dermal contact with sediments
. incidental ingestion of swface soils
. dermal contact with surface soils
. ingestion of plants grown in contaminated soils
. incidental ingestion of subswface soils
. dennal contact with subswface soils
. inhalation of volatile contaminants released from the soil into the ambient air
. inhalation of resuspended particUlates. '
Tables 15 through 19 list the exposure pathways that were considered complete in the
BLRA for each site and land-use scenario.
The exposure factors used for these three land-use scenarios follow, in general, EPA
Region 10 guidance {Table ID-la and ID-lb in EPA 1991a). Exposure factors for both
"Average Exposure" and the more conservative "Reasonable Maximum Exposure" cases
were used. The factors used are listed in the 22 tables in Appendix B of the BLRA (U.S.
Air Force 1993c). There was some diversion from the standard default exposure factors
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TABLE 12. Exposure Point Concentrations for ST13 and OP26 Risk
Assessment
Contaminant Surface Subsurface Ground
of Concern Soil Soil Water
(J,lg/kg) (J,lg/kg) (J,lg/L)
Volatile Compounds
Benzene 4.05E+03 2.78E+02
Chloroform 1.00E+OO
Chloromethane 3.00E+OO
Ethylbenzene 1.09E+04 2.18E+02
Toluene 1.96E+04 8.66E+02
Xylenes . (total) 1.42E+03
Semivolatile Compounds
Benzo(a)anthracene . 1.08E+:03 1.60E+02
Benzo( a )pyrene 1.25E+03 8.80E+01
Benzo(b )fluoranthene 1.42E+03 1.20E+02
Benzo(g,h,ncervlene 7.60E+02
Benzo(k)fluoranthene 1.49E+03 1.00E+02
Chrvsene 1.42E+03 1.80E+02
Dibenz( a, h)anthracene 4.70E+02
Indeno(1,2,3-cd)cyrene 8.22E+02 4.70E+01
Naphthalene 7.04E+01
Pyrene 2.14E+03 1.40E+03
Pestici~es
4.4'-000 9.36E+02
4,4'-00E 3.24E+02
4,4 '-DOT 5.31E+03
Metals
Antimony 1.28E+01
Arsenic 1.01E+04 9.71 E+03 2.67E+01
Barium 2.64E+02
Beryllium a.60E-01
Cadmium 1.20E+OO
Manganese 3.46E+05 .5.00E+05 5.25E+03
Thallium 1.00E+OO
resulting from site-specific characteristics. Those exposure factors that do not adhere to the
guidance are described below.
The exposure duration for the average exposure scenario for industrial land is 9 years.
This assessment assumed that this value should be equivalent to the average residence in a
home (BFA 1991a). .
Exposure duration for soils and sediments, both ingestion and dennal contact, and
particulate inhalation differ from standard EP A default parameters. The values were
adjusted to compensate for the sub-arctic climate at Eielson AFB. The values used (146
days for industrial and 180 days for residential) were adjusted based on the number of days
in Fairbanks without snow cover. The mean number of days without snow cover at
Fairbanks is 146 days; 180 days is presented as a reasonable maximum value. These
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Eielson Air Force Base
TABLE 13. Exposure Point Concentrations for ST18 Risk Assessment
Contaminant Surface Subsurface Ground
of Concern Soil Soil Water
(~a/ka) (ua/ko) (~q/L) .
Volatile Compounds
Chloroform 12.00E+OO
Trichloroethene 1 2.00E+OO
Semivolatile Compounds
Benzol a)anthracene 4.00E+02
BenzoCa)Dvrene 4.82E+02
BenzoCb)fluoranthene 4.48E+02
BenzoC a,h, j)pervlene 6.10E+02
BenzoCk)fluoranthene 4.49E+02
Chrvsene 4.91 E+02
Dibenz(a,h)anthracene 9.40E+01
Indeno( 1,2;3-cd)Dvrene 5.23E+02
N-nitrosodiphenvlamine (1) 3.00E+OO
Pvrene 5.80E+02
Meta Is
Arsenic 1.20E+04 3.70E+03 4.30E+01
Bervllium 4.66E+02
Cadmium 5.52E+OO
Manaanese 5.11 E+05 3.40E+05 1.63E+03
Thallium. 1.20E+OO
values were initially advanced in Appendix A of the Management Plan for OUs 3, 4, and 5
(Battelle 1992). The effect of adjustment is discussed in the uncertainty ~tions for each
site.
There are no known subsistence or sport fISheries at Eielson AFB~ and the exposure factors
for the fish ingestion pathway reflect this (Appendix B of U.S. Air Force 1993c). The
limited size and depth of the surface water bodie$ (Hardfill Lake and Ganison Slough)
should preclu.de these subgroups in the future.
The input concentrations for groundwater B1EX for future scenarios at ST19 are derived
from fate and transport modeling using the Multimedia Environmental Pollutant
Assessment System (MEP AS). The primary focus was to model future concentratiQns of
contaminants in groundwater (BTEX) that would be transported through the leachate
pathway from soil contamination present today. The results indicated that benzene and
toluene concentrations have been and will continue to decrease. In addition, the area of
groundwater contamination is limited to approximately 2 acres. Ethylbenzene and xylene
concentrations will increase. Modeling results indicate that benzene and toluene
concentrations should eventually reach values near their MCLs. The modeled peak .
concentration for ethylbenzene may exceed its MCL; xylene should not exceed its MCL.
Some of the assumptions associated with modeling assessment are as follows:
.
Each component in the BlEX waSte can be modeled as a separate and independent
constituent
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Eielson Air Force Base
TABLE 14. Exposure Point Concentrations for ST 19 Risk Assessment
Contaminant Surface Subsurface Ground
Of Concern Soil Soil Water
(~g/kg) (~g/kg) (~g/L)
Volatile Compounds
Benzene 8.50E+OO
Ethylbenzene 2.50E+02
Toluene 9.40E+02
Xylenes . (total) 1.46E+03
Semivolatile Compounds
Benzo( a)anthracene 5.20E+01
Chrysene 1.67E+02
Pyrene 4.50E+02
Metals
Antimony 2.59E+01
Arsen ic 1.94E+04 4.10E+03 4.00E+01
Barium 2.20E+02
Beryllium 3.40E+02 3.10E-01
Cadmium 2.1 OE+OO
Manganese 6.57E+05 1.7E+05 7.40E+03
Thallium 8.00E-01
Parameters that are typically used in calibrating models with the same level of detail as
MEP AS include distribution coefficients, pore-water velocities, and mass-flux rates
from the source. These parameters are generally not well known and can be modified
to ensure that the model can predict the anival of a contaminant at a monitoring well at a
given concentration leveL Although different combinations of the parameters result in
similar consequences, many of those combinations result in unrealistic values for some
of the parameters. By using realistic values for these parameters, the calibration
process at least ensures that the concentrations predicted by the model are the right
order of magnitude and representative of the problem at hand
. . In many of the simulationS, the zone of mixing is assumed to be 10 feet Limitiitg the
depth over which the mixing occurs attempts to account for the lower densities (=0.88
gtcm3) associated with the light nonaqu~us phase liquids (LNAPLs) in the BTEX
constituents.
.
.
Monitored data containing time-varying, groundwater concentrations were available at.
ST19 (Table 9). This information was utilized to calibrate the model used in the
preliminary transport and fate analysis for recreating the initial contamination of
groundwater at the site. . .
A more deWled description of the models used is in Section 8.3 and Appendix C of the
BLRA (U.S. Air Force 1993c). .
.'
6.1.3
Toxicity Assessment
The values and references for all toxicity data used in the risk assessment are given in
. Table 9.1 of the BLRA (U.S. Air Force 1993c). Table 20 is an abbreviated listing of the
-------
TABLE 15. Summary of Human Exposure Pathways for ST10 and SS14
Current Land-Use Future Land-Use
Theoretical Pathways Industrial Residential I n.d us tr I a I
Inaestlon of aroundwater used as potable water succlv X X X
Inhalation of and dermal contact with contaminants durlna aroundwater use X X X
Incidental Inaestlon of surface water X X X
Dermal contact with surface water X X X
Inaestlon of fish from Hardflll Lake X X X
Incidental Ineestlonof surface solis X X X
Dermal contact with surface solis X X X
Inaestlon of clants grown In contaminated solis - X -
Incidental Inaestlon of subsurface solis X X X
Dermal contact with subsurface solis X X X
Inhalation of volatile contaminants released from the soli Into the ambient air. X X X
Inhalation of resuspended particulates X X X
X = pathway retained for quantitative risk evaluation
. = pathwav eliminated see text for elimination rationale'
tria
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TABLE 17. Summary of Human Exposure Pathways. for ST13 and DP26
Current Land-Use Future Land-Use
Theoretical Pathways Industrial Res I dentla I Industrial
Inaestlon of aroundwater used as Dotable water sUDDlv - X X
Inhalation of and dermal contact with contaminants durlna aroundwater use - X X
Incidental Inaestlon of surface salls X X X
Dermal contact with surface soils X X X
Ingestion of Dlants arown In contaminated salls - X -
Incidental Inaestlon of subsurface soils X X X
Dermal contact with subsurface salls X X X
Inhalation of volatile contaminants released from the soli into the ambient air X X X
Inhalation of resuspended particulates X X X
X = pathway retained for quantitative risk evaluation
- = pathway eliminated. see text for elimination rationale
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TABLE 18. Summary of Human Exposure Pathways for ST18
Current Land-Use Future Land-Use
~ Theoretical Pathways Industrial Residential Industrial
Inaestlon of aroundwater used as Datable water SUDDlv - X X
Inhalation of and dermal contact with contaminants durina aroundwater use - X X
Incidental Inoestlon of surface soils X X X
Dermal contact with surface solis X X X
Inaestlon of Dlants arown In contaminated soils - X -
Incidental InaestJon of subsurface solis X X X
Dermal contact with subsurface salls X X X
Inhalation of volatile contaminants released from the soil Into the ambient air X X X
Inhalation of resuspended particulates X X X
X = pathway retained for quantitative risk evaluation
-------
TABLE 19. Summary of Human Exposure Pathways for ST19
Current Land-Use Future Land-Use
Theoretical PathwaYs Industrial Residential Industrial
Inaestlon of aroundwater used' as Dotable water supplv - X X
Inhalation of and dermal contact with contaminants durina aroundwater use - X X
Incidental Incestlon of surface solis X X X
Dermal contact with surface soils X X X
lnaestlon of clants crown In contaminated solis - X -
Incldental.lnaestlon of subsurface soils X X X
Dermal contact with subsurface solis X X X
Inhalation of volatile contaminants released from the soli Into the ambient air X X X
Inhalation of resusDended Dartlculates X X X
X = pathway retained fo.r quantitative risk evaluation
. = Dathwav eliminated. see text for elimination rationale
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-------
TABLE 20. Toxicity Data Used for Risk Assessments
Cancer Potencv Factor RfD
(mg/kg'od)-1 (mg/kgod)-1 (mg/kgod) (mg/kgod)
Analyte Oral Reference Inhalation Reference Oral Reference Inhalation Reference
Ivolatlle Compounds
Benzene 2.90E-02 ,5 2.90E-02 5
!chloroform 6.10E-03 5 8.1 OE-02 5 1.00E-02 5
Chloromethane 1.30E-02 3 6.30E-03 3 5.40E-01 2
Ethvlbenzene 1.00E-01 5 2.86E-01 ' 5
Toluene 2.00E-01 5 5.70E-01 5
Trlchloroethene 1.10E-02 7 1.70E-02 '3
Xvlenes (total) 2.00E+OO 5 8.60E-02 3
Sem Ivolatlle Compounds
Anthracene 2.34E+OO 1 1.95E+OO 1 3.00E-01 5
Benzola )anthracene 1.06E+00 1 8.85E-01 1
Benzol a )Dvrene 7.30E+OO 5 6.10E+OO 5
BenzolbHluoranthene 1.02E+OO 1 8.54E-01 1
Benzola.h.nDervlene 1.61E-01 1 1.34E-01 1
lBenzoek)fluor anthen e 4.82E-01 1 4.03E-01 1
Chrvsene 3.21 E-02 1 2.68E-02 1
Dibenze a.h }anthracene 8.1 OE+OO 1 6.77E+OO 1
Indenoe 1.2.3-cd}Dvrene 1.69E+OO 1 1.42E+OO 1
N-nltrosodiDhenvlamlne (1) 4.90E-03 5
'NaDhthalene 4.00E-02 4 4.00E-03 4
Pvrene 5.91 E-01 1 4.94E-01 1 3.00E-02 5
PCB
Aroclor-1260 7.70E+OO 6 7.70E+OO 6 I I
Pesticides
4.4'-DDD 2.40E-01 5 2. 50E-O 1 5
4.4'-DDE 3.40E-01 5
4 4'-DDT 3.40E-01 5 3.40E-01 5 5.00E-04 5
Aldrin 1.70E+01. 5 1. 70E+0 1 5 3.00E-05 5
Metals
"ntlmonv 4.00E-04 5
"rsenlc 1.75E+OO 4 1.20E+01 5 3.00E-04 5
-------
,
TABLE 20.. Toxicity Data Used for Risk Assessments (Continued)
. Cancer Potency Factor RfD.
Cmc/kcedl-1 (mc/kcedl-1 Cmc/kaed\ (ma/ko.d)
Analvte Oral Reference Inhalation Reference Oral Reference Inhalation Reference
Bervllium 4.30E+OO 5 8.40E+OO 5 5.00E-03 5
Icadmlum 6.1 OE+OO 5 . 5.00E-04 5
Manaanese 1.40E-03 5 1. 1 OE-04 5
Thallium' 8.00E-05 5
1. Clement Associates. 1988. Comparative Potency Approach for EstimatlnQthe Cancer Risk Associated with Exposure to Mixtures 01
Polv~vcllc AromAtl~ Hvd'rncarhnns. Interim Final Report, Clement Associates, Fairfax, Virginia.
? EPA. 1984. .Summary of Current Acceptable Dally Intakes (AD IS) for Oral Exposure." Environmental Criteria and Assessment Office,
plnclnnatl, Ohio.
~. EPA. 1991. Health Effects Assessment Summarv Tables. PB91-921199, U.S. Environmental Protection Agency, National Technical
Information Service, Springfield, Virginia.
4. EPA. 1992a. Health Effects Assessment Summarv Tables. NTIG/PB92-921199, U.S. Environmental Protection Agency, National Technical
Information Service, Springfield, Virginia. .
5. EPA. 1992b. Integrated Risk Information System (IRIS) (Online). U.S. Environm~ntal Protection Agency, Office of Health and
Environmental Assessment, Environmental Criteria and Assessment Office, U.S. Environmental Protecti~n Agen.cy, Cincinnati, Ohio.
6. Cancer Potency Factors set equal to values for PCBs, general
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£ielson Air Force Base
toxicity data for the contaminants of concern only. Toxicity data are divided into
carcinogenic (slope factors [SFs]) and noncarcinogenic (reference dosages [RIDs]).
SFs have been developed by EP A's Carcinogenic Assessment Group for estimating excess
lifetime cancer risks associated with 'exposure to potentially carcinogenic contaminants of
concern. SFs, which are expressed in units of (mglkg-day)-l, are multiplied by the
estimated intake of a potential carcinogen, in mglkg-day, to provide an upper-bound
estimate of the excess lifetime canter risk associated with exposure at that intake level. The
tenn "upper bound" reflects the conservative estimate of the risks calculated from the SF.
Use of this approach makes underestimation of the actual cancer risk highly unlikely. SFs
are derived from the results of human epidemiological studies or chronic animal bioassays
to which animal-to-human extrapolation and uncertainty factors have been applied (e.g., to
account for the use of animal data to predict effects on humans).
RIDs have been 'developed by EP A to indicate the potential for adverse health effects from
exposu're to contaminants of concern exhibiting noncarcinogenic effects. RIDs, which are
expressed in units of mglkg-day. are estimates of lifetime daily exposure levels for'
, humans, including sensitive individuals. Estimated intakes of {;ontaminants of concern
from environmental media (e.g.. the amount of a Contaminant of concern ingested from
contaminated drinking water) can be compared to the RID. RIDs are derived from human
epidemiological studies or animal studies to which uncertainty factors have been applied
(e.g., to account for the use of animal data to predict effects on humans).
No EP A toxicity data exist for two of the principal contaminants at OU2 sites: lPHs and
lead. Thus, these compounds were not included in the primary risk calculations. The
lPH-rich contamination encountered at OU2 is believed to have resulted from past spills
and leaks of fuels. Because of the variability of fuel degradati9n in soil, no toxicity value
exists. Nevertheless, the sample with the highest 1PH concentration at each site,also had a
comprehensive analysis of volatile and semivolatile organic compounds. Lead
concentrations in groundwater and soils were compared to EP A guidance for soils
(500 mglkg) and a groundwater action level of 15 Jig/L. Maximum total lead groundwater
concentrations at STlO, SSI4, STI3, and DP26 exceed this action level.
6.1.4 Risk Characterization (current and future)
The exposure point concentrations listed in Appendix F of the BLRA (U.S. Air Force
1993c) for each site were used with the toxicity data in Table 20 to calculate the risks for
carcinogens and noncarcinogens at each of 'the OU2 sites. '
For carcinogens, risks were estimated as the incremental probability of an individual
developing cancer over a lifetime as a result of exposure to the carcinogen. Excess lifetime
cancer risk was calculated from the following equation:
Risk ~ CD! x SF
where:
Risk = a unitleSs probability (e.g., 2 x 10-5) of an individual developing cancer
CDI = chro~c daily intake average over 70 years (mglkg-day)
SF = slope factor' (mg/kg-day)-l
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These risks are probabilities that are generally expressed in scientific notation (e.g.,
I x 10-6 or IE-6). An excess lifetime cancer risk of 1 x 10-6 indicates that, as a
reasonable maximum estimate, an individual has a I in 1,000,000 chance of developing
cancer as a result of site-related exposure to a carcinogen over a 70-year lifetime under the
specific exposure conditions at a site. .
. For noncarcinogens, the potential effects were evaluated by comparing an exposure level
over a specified time period (e.g., lifetime) with a reference dose derived for a similar
exposure period. The ratio of exposure to toxicity is called a hazard quotient (HQ). By
adding the HQs for all contaminants of concern within a medium or across all media to
which a given 'populationmay reasonably be exposed, the Hazard .Index (HI) can be
generated.
The HQ is calculated as follows:
Noncancer HQ = CDIIRfD
. where:
CDI = chronic daily intake
RID = reference dose
CDI and RID are expressed in the same units and represent the same exposure period (i.e.,
chronic, subchronic, or short tenn).
Risk calculations were made for each of the three land-use scenarios, all associated
exposure pathways, and for two different exposure cases--"average exposure" and
"reasonable maximum exposure."
Tables 21 through 25 summarize by site the risk calculation results. Each table lists the
cancer risk and the In for each exposure pathway individually. The values presented are
for the "reasonable maximum exposure ,case" only. A total cancer risk value and a total HI
are presented that add all of the exposure pathway risks together.
The risk values presented exclude the contribution from potential background metals.
Some areas of Fairbanks, Alaska, are noted for elevated concentrations of metals, in
, particular iron, manganese, and arsenic in the groundwater (Cederstrom 1963; Nelson
1978; Krumhart 1982; Weddleton et ale 1989). These metals and several others including
antimony, barium, beryllium, cadmium, and thallium were found to occur at elevated
concentrations at OU2. Many 'of these metals exceed risk-based screening concentrations,
and background samples for both soil and groundwater were collected to help identify
which metals could be considered equivalent to site background and not the result of base
activities. U.S. Air Force (1993e, f) has documented the results of the Eielson AFB site-
wide background sampling efforts.
The m~ at OU2 sites were statistically compared to site. background in section E.l of the
BLRA (U.S. Air Force 1993c). The metals that could not be conSidered statistically
equivalent to background were compared to concentrations of metals believed to be
background (i.e~, iron) in Section E.2. This additional step was necessary, in part,
because the background groundwater samples were collected in June when groundwater is
diluted with snow melt OU2 groundwater samples were collected during August and
September when dilution is minimal No background data exist for several metals. One of
these, thalliwn, occurs in concentrations that exceed risk-based screening concentrations.
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TABLE 21. Summary of Cancer Risk and Hazard Index lor the Reasonable Maximum Exposure Case at STI0/SS14
Land-Use ScenarIo
Current Industrial Future Industrial Future Residential.
Cancer Haza rd Cancer Hazard Cancer Hazard
Exposure Pathway Risk Index Risk. Index Risk Index
Ingestion of groundwater 6x10-5 0.1 6x 10- 5 0.01 2x10.4 0.4
Inhalation/dermal contact groundwater use 9x10-4 2 9x 10.4 2 2x10-3 3
Incidental Ingestion of sediments 4xI0-7. <0.01 4x10-7 <0.01 3x10-6 <0.01
Dermal contact with sediments 4x10-7 <0.01 4x 10-7 <0.01 9x10-7 <0.01
Ingesllon 01 .plants grown in contaminated soils NA NA NA NA aX10-6 <0.01
Incidental Ingestion of surface solis 5X10-7 <0.01 5x10-7 <0.01 4x 10.6 <0.01
Dermal contact with surface solis 5X10-7 <0.01 5X10-7 <0.01 Ix10.6 <0.01
Incidental ingestion 01 subsurface solis <1X10-7 <0.01 < Ix 10.7 <0.0-1 3X10.7 <0.01
Inhalation of volatile compounds from soils IX10.6 <0.01 1 x 10.6 <0.01 1 XI 0.6 <0.01
Summation for all exposure pathways 1 x 1 0.3 2 Ix10-3 2 2x10.3 4
NA = not analyzed because the pathway was not considered complete under this land-use scenario
I r.:0I:fiAL FACILITIES s~ ~h.
TABLE 22. Summary of Cancer Risk and Hazard Index for the Reasonable Maximum Exposure Case at ST11
Land-Use. Scenario
Current Industrial Future. Industrial Future Residential
Cancer Hazard Cancer Hazard Cancer Hazard
Exposure Pathway Risk Index Risk Index Risk Index
Inhalation/dermal contact groundwater use
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TABLE 23. Summary of Cancer Risk and Hazard Index for the Reasonable Maximum Exposure Case at ST13/DP2S
Land-Use Scenario
Current Industrial Future Industrial Future Residential
Cancer Hazard Cancer Hazard Cancer Hazard
Exposure Pathway Risk In d e x. Risk Index Risk Index
Ingestion of -groundwater NA NA 3x10.5 0.09 1X10-4 0.2
Inhalation/dermal contacf groundwater use NA. NA 3x10-4 2 4x10-4 3
Ingestion of plants grown In contaminated soils NA NA NA NA 3X10-5 0.03
Incidental Ingest/on 0' surface soils 2x 10- 6 <0.01 2x 10.6 <0.01 2x10.S 0.02
Dermal contact with surface soils 2x 10.6 <0.01 2x10-6 <0.01 5x10.S <0.01
Incidental ingestion 0' subsurface solis 1X10.7 <0.01 <1X10-7 <0.01 1X10.S <0.01
Dermal contact with subsurface soils 1x10.7 <0.01 <1X10-7 <0.01 3X10-7 <0.01
Inhalation of volatile compounds from soils 1x10-6 <0.01 1X10-6 <0.01 2X10-S <0.01
S-ummation for all exposure pathways 1x10-s 0.01 3x 10- 4 2 6X10.4 3
NA = not analyzed because the pathway was not considered complete under this land.use scenario
TABLE 24. Summary of Cancer Risk and Hazard Index for the Reasonable Maximum Exposure Case at ST18
Land-Use Scenario
Current Industrial Future Industrial Future Residential
Cancer Hazard Cancer Hazard Cancer Hazard
Exposure Pathway Risk rn de x Risk Index Risk Index
Ingestion of groundwater NA NA < 1 x 1 0- 7 <0.01 SX10.7 <0.01
Inhalation/dermal contact groundwater use NA . NA 5x 10.6 <0.01 9x10-S <0.01
Ingestion of plants grown In contaminated soils NA NA NA NA 1x10-S <0.01
Incidental Ingestion of surface soils. 7x10-7 <0.01 7x10-7 <0.01 5x10-S <0.01
Dermal contact with surfaca soils 7x 10-7 <0.01 4x 10-7 <0.01 2x10-6 <0.01
Inhalation of volatile compounds from soils < 1x 10-7 <0.01 < 1 x 10.7 . <0.01 SX10.7 <0.01
Isummation for aU exposure pathways ; 1x10-6 <0.01 7x10-6 <0.01 3x10.S <0.01
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TABLE 25. Summary 01 Cancer Risk and Hazard Index for the Reasonable Maximum Exposure Case at ST19
. Land-Use Scenario
Current Industrial Fut u re Industrial Future Residential
Cancer Hazard Ca nee r H aza rd Cancer Hazard
Exposure Pathway Risk Index. Risk Index Risk Index
Ingestion ot groundwater NA NA 9X10.7 0.02 3x 10.6 0.5
Inhalation/dermal contact groundwater use NA NA 8x10-6 7 1X10-5 8
~ummation tor all exposure pathways < 1 x 1 0.7 <0.01 8x10-6 7 2x10.5 9
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£ie/son Air Force Base
Section E.3 (U.S. Air Force 1993c) discusses metals that have no groundwater
background data. No background data exist for surface waters.
Except for lead, the concentrations of all metals in all media were not considered the result
of base activities. Except for lead, no known human-caused sources of metals exist at
OU2. .
Because risk assessments were perfonned on five sets of sites at OU2, this ROD does not
present quantified carcinogenic risks and HQs for each contaminant of concern in each
exposure medium for each exposure pathway. Appendix K of the BLRA (U.S. Air Force
1993c) summarizes these data.
Table 21 indicates that excess cancer risk to human health in a future residential land-use
scenario presents an unacceptable risk at STIO and SS14. Furthermore, the HI is greater
than unity. Based on these estimates, the primary exposure pathway of concern for STIO
and SS 14 under all land-use scenarios.is the consumption and use of contaminated Table
groundwater. Ingestion of and.dennal contact with contaminated surface soils and shallow
sediments may also present an excess cancer risk greater than I x 10-6 under the futUre
residential scenario. .
The contaminants of concern in groundwater are BTEX, anthracene, and naphthalene.
Benzene contamination of subsurface soil may also present a future risk to groundwater.
Based on the BLRA (U.S. Air Force 1993c), the only exposure pathway of potential
concern for ST11 is inhalation of and dermal contact with benzene during use of
contaminated groundwater. However, the cumulative risk (rom all potential pathways does.
not present an unacceptable risk (Table 22). . . .
The primary exposure pathway of concern for ST13 and DP26 under the future land-use
scenarios (Table 23) is the consumption and use of contaminated groundwater. Ingestion
of and dermal contac.t with contaminated surface soils may also present an excess cancer
risk greater than 1 x 10-6 under all of the land-use scenarios. Ingestion of vegetables
grown in contaminated soil may present an excess cancer risk greater than 1 x 10-6 for the
future residential scenario. .
The contaminants of concern in groundwater are BTEX and naphthalene. Benzene; .
ethyl benzene, and toluene contamination of subsurface soil may also present a future risk to
groundwater.
The primary exposure pathway of potential concern for ST18 is the consumption arid use
of contaminated groundwater (fable 24). Ingestion of and dermal contact with
contaminated surface soils and ingestion of vegetables grown in contaminated soil may also .
present an excess cancer risk greater than 1 x 10-6 under the future residential scenario.
However, the cumulative risk from all potential pathways does not present an unacceptable
risk. .
The only exposure pathway of potential concern for ST19 is the consumption and use of
contaminated groundwater (Table 25). The cumulative risk from all potential pathways
does not present an unacceptable risk; however, the HI, based on the potential for future
leaching of contaminants to groundwater, exceeds unity.
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Eielson Air Force Base
6.1.5
Uncertainty
Health risk assessment methodology has inherent uncenainty associated with how
accurately the calculated risk estimates represent the actual risk The effects of the
assumptions and the uncertainty factors may not be known. Usually, the effect is difficult
to quantify numerically (e.g., in terms of an error bar). As a result, the effect is discussed
qualitatively. Some of the assumptions and uncertainty factors associated with the ~LRA
include the following:
. This assessment used EP A Region 10 default exposure parameters for most
calculatio~. Some of these parameters are not realistic for a subarctic climate (may
overestimate risk).
. The toxicity of TPH and lead is inconcluSive; neither was included in the primary
calculations in the BLRA (may underestimate risk).
. . .
Existing concentrations are assumed to be the concentrations or exposure source.
terms in the future. No reduction from natural degradation and attenuation over
time is taken into account except where fate and transport modeling has been
performed (STI9). No increase because of additional contamination is assumed
(except where fate and transport modeling was performed). Potential degradation
products of existing organic contaminants (e.g., benzene) are not considered (may
overestimate or underestimate risk).
. The groundwater detection limits for some organic and inorganic contaminants,
especially PAHs, are higher than risk-based screen concentrations (may
~derestimate risk). .
. Most sampling at the OU2 sites was conducted during the late summer. Seasonal
changes may impact soils and groundwater contamination (may overestimate or
.underestimate risk).
. Surface soil samples were composited from three to five locations. They may have
missed hot spots of surface contamination (may underestimate risk).
. Primary risk calculations were based on data collected during the 1991 field season.
This data set presents only a brief snapshot of site contamination (may overestimate
or underestimate risk). .
. Comprehensive soil analyses were analyzed where TPH was most concentrated.
This analysis may not have been the most representative of volatile and semi-
volatile contamination (may underestimate risk).
6.2 Environmental Risks
.
No acute ecological hazards were identified at OU2. Both STI0 and STII are adjacent to
surface water bodies, Hardfill Lake and Garrison Slough, respectively. Benzene, at a
concentration of 2 ~gIL, was the only organic contaminant detected in the waters of
Hardfill Lake; no organic contaminants were detected in Garrison Slough adjacent to
ST11. The metals concentrations in these surface waters were less than or equivalent to
their concentrations in the adjacent groundwaters. Total lead in Hardfill Lake had a
maximum concentration of 1.7 J1g1L. No contaminants were detected above risk-based
standards in the sediments at STll. PAHs, PCB, and DDD were detected in the sediments
at STlO.
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HardfIll Lake is downgradient of the contaminated groundwater at ST10 and SS 14. In the
past (U.S. Air Force 1993a), sheens and odors have been reported for the surface waters at
Hardfill Lake. Thus, there is a strong potential that contaminants may flow into the lake
and affect environmental receptors.
An ecological risk assessment is presently under way as part of the Eielson AFB site-wide
study. .
Description. of Alternatives
A feasibility study (FS) was performed as part of the OU2 RIlFS process. This section of
the ROD describes the remedial alternatives proposed in the FS. For more details, see the
FS (U.S. AirForce 1993d).
7.0
7.1
Remedial Action Objectives (RAOs)
RAOs are deyeloped to specify actions and contaminant levels necessary to provide
protection of human health and the environment RAOs define the contaminants of
concern, exposure routes and receptors, and an acceptable contaminant level for each
exposure route (Le., a remediation goal). The results of the baseline risk assessment (U.S.
Air Force 1993c) are used to determine the potential for current or future risk from a given
source area and to identify acceptable contaminant levels for each exposure pathway.
Health-based applicable or relevant and appropriate requirements (ARARs) are also usedto
establish remediation goals when they are available. In addition, groundwater
concentrations are compared to drinking water standards as specified by the EP A's
groundwater protection strategy. The goal of EP A's Superfund approach is to return
usable groundwaters to their beneficial uses within a timeframe that is reasonable given the
particular circumstances of the site.
7.1.1 Source Areas STH and ST18
For source areas STII and STI8, the cumulative risk from all current and future potential .
pathways is within acceptable regulatory levels, and groundwater concentrations do not
'exceed MCLs. Soil and groundwater concentrations are protective of human health. and the
environment and, therefore, no remedial action is required at these source areas.
Although no action is required under CERC~ the U.S. Air Force will remove the tanks
at STl8 under the Underground Storage Tank Program. In addition, if the drywellat STl8
can be located and removed without damaging the existing strucmres, it will be removed.
Confirmatory soil samples will be collected in either case. The U.S. Air Force will also
continue to monitor groundwater at these areas to ensure that contaminant levels remain
protective of human health and the environment
7 .1~2 . Source Area ST19
The exposure pathway of potential concern for ST19 is consumption and use of .
contaminated groundwater in the event that groundwater directly adjacent to the spill area is
used in the future. Groundwater concentrations at levels approximately two times the
MCLS for benzene and toluene were found in one monitoring well (19-02A) located .
approximately 150 feet from the spill area. Fate and transport modeling conducted for this
area indicate that benzene and toluene concentrations have been and will continue .
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Eielson Air Force Base
decreasing. Using conservative modeling assumptions, the modeled peak concentration for
ethylbenzene is estimated to be approximately 900 ~gIL and, therefore, may exceed its
MCL of 700 ~gIL at some time in the future. Xylene concentrations are not expected to
exceed the MCL.
Soil and groundwater sampling results and the fate and tiansponmodeling both indicate
that the contamination at STl9 is restricted to a limited area (approximately 2 acres) directly
adjacent to the spill area and that the weathered petroleum contamination in subsurface soils
is not expected to act as a significant continuing source of groundwater contamination.
Groundwater concentrations in wells located downgradient within 1,000 feet of the spill
area do not exceed MCLs. In addition, STl9 is located in a remote area of the base that is
not likely to be used for residential purposes in the foreseeable future. Given the low level
of residual contamination present and the limited area impacted, no remedial action will be
taken at ST19. Institutional eontrols (e.g., command directives and protective covenants) .
will be established to prevent the use of groundwater at ST19 and th~ groundwater will
continue to be monitored to verify the results of the fate and transport modeling and to
ensure protectiveness of human health and the environment.
7.1.3
Source Areas STI0, SSI4, STI3, and DP26
Based on [mdings of the RI and BLRA, source areas STIO, SS14, ST13, and DP26
require remedial action because of the potential risk from unrestricted domestic use of
groundwater. These source areas are characterized by the presence of petroleum-derived
contaminants in the soil (BTEX and naphthalenes), floating fuel in the smear zone at the top
of the water table, and petroleum-derived contaminants (BTEX, naphthalenes, total lead) in
the groundwater. The potential risks ,are primarily associated withBTEX, total lead, and
naphthalene in the groundwater. The soils do not pose 'an unacceptable risk due to '
ingestion or dermal contact under either the current industrial or future residential scenarios,
but residual contamination in the soil and smear zone may be a con~uing source of
releases to the groundwater, and, therefore, may also contribute to 'the potential risk. The
chemicals of concern by media for the four source areas recommended for remedi~ action
are swnmarized in Table 26.
. .
TABLE 26. Chemicals of Concern by Media
Media 5T10 and 5514 5T13 and DP26
Groundwater' Benzene, Benzene
Toluene Toluene
Ethylbenzene Ethylbenzene
Xylenes Xylenes
Naphthalenes Naphthalenes
T otallead T otallead
Subsurface soil Benzene Benzene
Naphthalenes Toluene
Ethylbenzene
Xylenes
Nachthalenes
The RAOs for the OU2 source areas are summarized in Table 27.
To achieve .pese objectives, remediation goals (Table 28) that identify acceptable
contaminant levels in soils and groundwater have been developed from risk-based
concentrations and chemical-specific ARARs.
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TABLE 27. Remedial Action Objectives
Environmental Media Remedial Action Objectives
Groundwater For Human Health:
Prevent use of water having carcinogens (benzene) in
excess of MCLs.
Prevent use of water having non-carcinogens (toluene,
ethylbenzene, xylenes, naphthalenes, total lead) in excess
of MCLs or RIDs
For Environmental Protection:
Restore aquifer to its designated beneficial use as a
drinkina water source
~oil For Environmental Protection:
Prevent migration .of contaminants that would result in
groundwater contamination in excess of MCLs or health-
based levels. .
TABLE 28. Rnal Remediation Goals
Groundwater Soil/Shallow
Chemical Compound .(Ji9/L) Sediments
(m~/k~)
!Benzene 5(a) 0.2(b)
rr oluene 1 ,OOO( a) so (b)
Ethylbenzene 700(a) 140(b)
~ylenes 10,000(a) 760(b)
Naphthalenes:
2-Methylnaphthalene 1 40 (c) 150(b)
Naphthalene 220(c) ' 21 (b)
Lead 15(a) 500 (d)
a)Sased 0;' chemical-specific ARARs. .
b)Sased on leaching to groundwa.ter [Appendix D of FS (U.S. Air Force
1993d)].
c)Sased on risk-based contaminant of concern cutoff concentration equivalent
o a Hazard Quotient of 0.1 (U.S. Air Force 1993c).
d)Sased on the EPA biokinetic uDtake model.
As stated previously, the primary RAO is protection of groundwater. . The secondary
remediation goals developed for soil are based on fate and transport modeling and may be
modified if additional information becomes available indicating that an alternative level of
soil remediation is protective of groundwater. .
7.2 STIO and 8814 Remedial Alternatives
Six alternatives were developed in the FS and.five were analyzed in detail for STIO and
SSI4. The sixth alternative proposed the complete removal of source (floating fuel and
contaminated soils) and extraction and treatment of contaminated groundwater. It would
include excavation of soils down to the water table and removal of the floating fuel layer,
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approximately 540,000 cubic yards of soil. This alternative was screened out because it
was not considered implementable; it would have required complete demolition of the E-2
POL Storage Area, and cost approximately $39,000,000.
The five alternatives analyzed in detail are listed below. ARARs for each alternative are
summarized in Table 29.
TABLE 29. Relationship between ARARs and Remedial Alternatives
ARARs Applicable Regulations Remedial Alternatives
and Codes 1 2 3 4 5
Action-Specific:
IAlaska soil waste management 18 MC 60 A A .A
IAlaska hazardous waste regulations 18 MC 62 A A A
RCRA land disposal restrictions 40 CFR 268 A A
RCRA waste piles regulations' 40 CFR 264.251 A A A A
Federal Clean Air Act 42 USC 7401 . A A
AWaC and Alaska discharge standards AWaC ~304/18 MC 70 A A A A
Chem i cal-S pecific:
MCl, non-zero MClGs, and action levels 40 CFA 141/18 MC 80 R A R R
. Alaska water quality standards 18 MC 70 A A A A
Alaska oil pollution regulations 18 MC 75 A A A
IAlaska regulations for leaking USTs 18 MC 78 A A R
lA-applicable
A-relevant and appropriate
~WaC=Ambient Water Quality Criteria
MCl=maximum contaminant level
MClG=maximum contaminant level goal
UST =underground storage tank.
7.2.1 Alternative 1: No Action Alternative
Under this alternative, no action would be taken to remove the floating fuel or remediate
contaminated soils or groundwater. No monitoring of soil or groundwater would be
conducted. .
7.2.2 Alternative 2: Limited Action Alternative
Under this alternative, no action would be taken to remove the floating fuel or remediate
contaminated soils or groundwater. Contaminants in the floating fuel, soil, and
groundwater would be allowed to disperse and degrade through natural attenuation. Some
natural groundwater treatment would continue through volatilization of contaminants
discharged to Hardfill Lake.
Institutional controls prohibiting domestic use of groundwater within the contaminated area
would .remain in place for as long as the contaminant concentrations in groundwater exceed
MCLs. Drinking water would continue to be supplied to the area from the main base water
supply system.
Groundwater monitoring would be conducted to evaluate contaminant migration and
compliance with final remediation goals.
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7.2.3 Alternative 3:
Bioventing Alternative
This alternative would employ passive skimming devices without gradient enhancement to
remove as much of the floating fuel as possible near the source and to prevent further
seeping of free phase fuel into Hardfill Lake. Bioventing would be conducted in the areas
where BTEX compounds were found in the subsurface soils at concentrations that might
present a future risk to groundwater. The total surface area biovented is approximately
30,000 square feet
Passive skimming will be used where free product is sufficiently mobile to flow, without'
an induced gradient, into wells and trenches. Its effectiveness will be evaluated before full-
scale implementation. The bioventing process uses a series of wells that inject air into the
soil. The oxygen in the air sustains and promotes the growth of naturally occUrring ,
microorganisms that break down the fuel contamination.
. .
This alternative addresses groundwater contamination by source reduction. It does not
include active remediation of the floating product and the smear zone soils.
Institutional controls prohibiting' domestic use of groundwater within the contaminated area
would remain in place for as long as the contaminant concentrations in groundwater exceed
MCLs. Drinking water would continue to be supplied to the area from the main base water
supply system. Groundwater monitoring would be conducted to evaluate contaminant
migration and compliance with fmal remediation goals.
7.2.4 Alternative 4: BioventinglSoil Vapor Extraction/Air
SparginglPassive' Ski mining Alternative,
This alternative would combine bioventing, soil vapor extraction (SVE), and possibly air
sparging to enhance volatilization and degradation of volatile organic compounds from the
vadose zone, smear zone, and floating fuel layer in areas where the layer is thin. The area
treated would include all of the site underlain by floating fuel, approximately 326,000
square feet Air would be introduced into the groundwater through injection wells for in
situ stripping of volatile organic compounds. The volatile organic compounds would be
removed using vapor extraction wells screened from the seasonal low water table up
through the vadose zone. A vacuum applied 19 the extraction wells would pull air through
. . the soils and across the surface of the floating fu~l. Air emission controls would be
installed on the SVE system if needed.' ' , ,
A cap may be used with the SVE system to enhance extraction efficiency (ie., reduce the
, number of extraction wells required) and prevent shon circuiting. The cap would cover the
surface above the SVE treatment area. This cap would also help reduce infiltration and
'migration of contaminants to the groundwater.
The frequency of switching between SVE and bioventing will be determined during the
phased approach. Since both systems will use the same plumbing systems, switching
between the systems will be readily implementable. For example. the SVE system could be
converted to bioventing for biodegradation of heavier fuel constituents in the soil. The .
shallow extraction wells could be converted to low-volume air injection wells to optimize
oxygen availability for microbial growth. Passive or active heating of the soil would be an
option. Implementation of the phased approach will be based on monitoring of the volatile
organic compound (VQC)-contaminated soils and floating fuel layer during remediation.
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Passive skimming devices would be used to remove floating fuel and prevent fuel from
seeping into Hardfill Lake. Passive skimming will be used where free product is
sufficiently mobile to flow, without an induced gradient, into wells and trenches.
Collection trenches that extend several feet below the water table would also be installed
perpendicular to the direction of groundwater flow. The floating fuel would enter slotted
pipes in the trench and flow by gravity to a sump where the oil would be removed using a
skimmer pump. Its effectiveness will be evaluated before full-scale implementation.
This alternative addresses groundwater contamination by source reduction. It does include
active remediation of the floating product and the smear zone soils.
Institutional controls prohibiting domestic use of groundwater within the contaminated area
would remain in place for as long as the contaminant concentrations in groundwater exceed
MCLs. Drinking water would continue to be supplied to the area from the main base water
supply system. Groundwater monitoring would be conducted to evaluate contaminant
migration and compliance with final remediation goals
7.2.5. Alternative 5: . Soil Excavation/Groundwater. Treatment Alternative
This alternative would include removal of known subsurface soil hot spots to the extent
practicable. Unsaturated soils (vadose and upper portion of the smear zone) that exceed the
final remediation goals for protection of groundwater would be excavated where excavation
is feasible without disrupting base activities and facilities.' Because the two source areas are
adjacent to fuel outlets. above-ground and below-ground storage tanks, pipelines,
buildings, and other facilities, only a small portion of the soil contaminated above rmal
remediation goals may actually be excavated The maximum surface area of the excavation
is approximately 30,000 square feet with an anticipated volume of 6,700'cubic yards of. soil
. excavated. The excavated soils could be treated by ex situ bioremediat,ion (e.g.,
composting).
This alternative would also include installation of product and groundwater extraction wells
with dual-phase active skimmer pumps to remove the floating fuel and contaminated
groundwater. The use of dual-phase pumps would create a small localized cone of
depression in the water table, enhancing free phase fuel flow to the skimming wells. The
effectiveness of active skimming will be evaluated before full-scale implementation. The
groundwater extracted during implementation of this alternative would be treated by air
. stripping and carbon adsorption to remove the volatile organic compounds. Pretreatment to
remove iron, arSenic, and lead may be required to prevent equipment fouling and to meet
discharge limits. The treated groundwater would be discharged to Hanifin Lake. Air
pollution controls would be installed if needed for protection of human health or
compliance with~. .
This alternative addresses groundwater contamination by extraction and treatment It does
include active remediation of the floating product and the smear zone soils where they are
accessible. A significant volume of soils may not be accessible for excavation.
. .
. Institutional controls prohibiting domestic use of groundwater within the contaminated area
would remain in place for as long as the contaminant concentrations in groundwater exceed. .
MCLs. Drinlcing water would continue to be supplied to the area from the main base water
supply system. Groundwater monitoring would be conducted to evaluate contaminant
migration and compliance with final remediation goals
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7.3 . ST13 and DP26 Remedial Alternatives
The five alternatives developed in the FS and analyzed in detail for ST13 and DP26 are
summarized below. '
7.3.1 Alternative 1: No Action Alternative
This alternative is identical to the no action alternative for STlO and SS14 (Section 7.2.1)
and assumes that no action would be taken to remove or remediate the floating fuel,
contaminated soils, or groundwater. No monitoring of soil or'groundwater would be
conducted.
7.3.2 Alternative 2: Limited Action Alternative
Under this alternative, no action would be taken to remove the floating fuel or remediate
contaminated soils or groundwater. Contaminants in the floating fuel, soil, and
groundwater would be allowed to disperse and degrade throu~h natural attenuation.
Institutional controls prohibiting domestic use of groundwater within the contaminated area
would remain in place for as long as the contaminant concentrations in groundwater exceed '
,MCLs. Drinking water would continue to be supplied to the area from the main base water
supply system.
Groundwater monitormg would be conducted to evaluate contaminant migration and
compliance with fmal remediation goals.
7.3.3 Alternative 3: Bioventing Alternative
This alternative would employ passive skimming devices without gradient enhancement to
remove the floating fuel near Tank 300. Bioventing would be conducted in the areas where
floating fuel exists and where BTEX compounds were found in the subsurface soils at
concentrations that might present a future risk to groundwater. The total surface area
biovented is approximately 128,000 square feet
Passive skimming will be used where free product is sufficiently mobile to flow, without
an induced gradient, into wells and trenches. Its effectiveness will be evaluated before full-
'scale implementation. The bioventing process uses a series of wells that injeCt air into the
soil. The oxygen in the air sustains and promotes the growth of naturally occurring
microorganisms that break down the fuel contamination.
This alternative addresses groundwater contamination by source reduction. It does not
include active remediation of the floating product and the smear zone soils.
Institutional controlS prohibiting domestic use of groundwater within the contaminated area .
would remain in place for as long ~ the contaminant concentrations in groundwater exceed
MCLs. Drinking water would continue to be supplied to the area from the main base water
supply system. Groundwater monitoring would be conducted to evaluate contaminant
migration and compliance with final remediation goals.
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7.3.4 Alternative 4: Bioventing/Soil Vapor Extraction/Air Sparging/Active
Skimming/Groundwater Treatment Alternative
This alternative would combine bioventing, SVE, and possibly air sparging to enhance
volatilization and degradation of volatile organic compounds from the vadose zone, smear
zone, and floating fuel layer in areas where the layer is thin. These. remedial technologies
would be implemented in the areas where floating fuel exists and where BTEX compounds
were found in the subsurface soils at concentrations that might present a future risk to
groundwater. The total surface area of the treated area is approximately 128,000 square
feet .
Air would be introduced into the groundwater through injection wells for in situ stripping
of volatile organic compounds. The volatile organic compounds would be removed using
vapor extraction wells screen,ed from the seasonal low water table up through the .vadose
zone. A vacuwn applied to the extraction wells would pull air through the soils and across
the surface of the floating fuel. Air emission controls would be installed on the SVE
system if needed. The frequency of s~tching between SVE and bioventing ~ be
determined during the phased approach. Since both systems \Yill use the same plumbing
systems, switching between the systems will be readily implementable. For example, the
SVE system could be converted to bioventing for biodegradation of heavier fuel
constituents in the soil. The shallow extraction wells could be converted to low-volume air
injection wells to optimize oxygen availability for microbial growth. Passive or active
heating of the soil would be an option. Implementation of the phased approach will be
based on monitoring of the VOC-contaminated soils and floating fuel layer during
remediation.
A cap may be used.with the SVE system to enh~ce extraction efficiency and prevent short
circuiting. The cap would be placed over the surface of the area. The cap would also help
reduce infiltration and potential migration of contaminants fro~ soils to the groundwater.
This alternative would also include the installation of a product and groundwater extraction
well near Tank 300 for active skimming of the floating fuel layer. The well' would be
equipped with a dual-phase skimmer pwnp to enhance fuel flow to the well. The
effectiveness of active skimming will be evaluated before full-scale implementation. When
no additional measurable floating fuel can be removed, groundwater would be extracted'
from the area with lead concentrations above final remediation goals. The groundwater
extracted during implementation of this alternative would be treated by precipitation to
remove the lead and air stripping to remove the volatile organic compounds.
.
The distal end of the benzene groundwater plwne will be monitored annually for 5 years, at
which time the need for further monitoring will be reevaluated. If the plume is expanding,
groundwater may be extracted from near the plwne's distal end to prevent contaminant
migration further downgradient The groundwater extracted from the hydraulic
containment well would also be treated in the precipitation/air stripping system.
This alternative addresses groundwater contamination by source reduction and by
extraction and treatment of contaminated groundwater. It does include active remediation
of the floating product and the smear zone soils.
Institutional controls prohibiting domestic use of groundwater within the contaminated area
would remain in place for as long as the contaminant concentrations in groundwater exceed
MCLs. Drinking water would continue to be supplied to the area from the main base water
supply system. Groundwater monitoring would be conducted to evaluate contaminant
migration and compliance with final remediation goals.
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7.3.5 Alternative 5: Soil Excavation/Groundwater Treatment Alternative
This alternative would include removal of known subsurface soil hot spots to the extent
practicable. Unsaturated soils (vadose and upper portion of the smear zone) that exceed the
final remediation goals for protection of groundwater would be excavated where excavation
is feasible without disrupting base activities and facilities. Because the two source areas are
adjacent to active taxiways, fuel outlets, above-ground and below-ground storage tanks,
pipelines, buildings, and other facilities, only a small portion of the soil contaminated
above final remediation goals may actually be excavated. The maximum surface area of the
excavation is approximately 3,000 square feet with an anticipated 660 cubic yards of soils
excavated. The excavated soils could be treated by ex situ bioremediation (e.g.,
composting).
This alternative would also include installation of product and groundwater extraction wells
with dual-phase active skimmer pumps to,remove the floating fuel and contaminated
groundwater. The use of dual-phase pumps would create a small localized cone of
depression in the water table, enhancing free phase fuel flow tQ the skimming wells. The
effectiveness of active skimming will be evaluated before full-scale implementation. The
groundwater extracted during implementation of this alternative would be treated by air
stripping and carbon adsorption to remove the volatile organic compounds. Pretreatment to .
remove iron, arsenic, and lead may be required to prevent equipment fouling and to meet
discharge limits. The treated groundwater would be. discharged to surface water bodies.
Air pollution controls would be installed if needed for protection of human health or
compliance with ARARs.
This alternative addresses groundwater contamination by extraction and treatment It does
include active remediation of the floating product and the smear zone soils where they are
accessible. A significant volume of soils may not be accessible for excavation.
Institutional controls prohibiting domestic use of groundwater within the contaminated area
, would remain in place for as long as the contaminant concentrations in groundwater exceed
MCLs. Drinking water would continue to be supplied to the area from the main base water
supply system. Groundwater monitoring would be conducted to evaluate contaminant
migration and compliance with fmal remediation goals
8.0
Summary of the Comparative Analysis of Alternatives
In accordance with federal regulations, the five cleanup alternatives were evaluated based
on the nine criteria presented in the National Contingency Plan (NCP). The results of this
evaluation are discussed in this section and depicted in Table 30.
8.1 Overall Protection of Human Health and the Environment
All the alternatives, except Alternative 1, would use institutional controls to prevent the use
of contaminated groundwater until cleanup standards are achieved. Alternatives 4 and 5
would provide the greatest protection of human health and the environment and the greatest
degree of cleanup by treating petroleum contamination in the soil and by treating ,
contaminated groundwater. Alternative 3 would provide limited protection by treating some
of the soil contamination and partially reducing the source of groundwater contamination.
However, Alternative 3 does not include groundwater treatment
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TABLE 30. Comparison of Cleanup Alternatives Using the Five Balancing Criteria.
Alternatives are ranked bv comparinQ them to each other.
Alternative Number and Ranking
Evaluation Criteria 1 and 2 3 4 5
Long-Term Effectiveness and Permanence 0 0 ~ ~
Reduction of Toxicity, Mobility, and Volume 0 0 ~ ~
Short- Term Effectiveness 0 0 . ~
I mplementability . . ~ 0
Cost
ST.1 0 and SS 14 . ~ 0 0
ST13 and DP26 . ~ 0 ~
Key . Best
~ Good
0 Poor
0 Worst
8.2 Compliance with Applicable or Relevant and Appropriate Requirements
Alternatives 4 and 5 include groundwater treabnent and are expected to achieve
groundwater cleanup standards more rapidly than the other alternatives that rely only on
natural processes to slowly decrease petroleum and lead concentrations in the groundwater.
Alternatives 3,4, and 5 would be designed and implemented to meet all applicable or
relevant and appropriate state and federal regulations, including air emission limitation.s,
surface water discharge limits, and disposal of byproducts from the groundwaf:er treatment
activities.
Alternatives 1 and 2 are not designed to meet all applicable or relevant and appropriate state
and federal regulations. Natural dispersion and degradation might eventually reduce
contaminant concentrations below ARARs. However, it will take a very long time
(decades).
8.3 Long- T~rm Effectiveness and Perma'nence
Alternative 4 aggressively treats the subsurface soils, including the smear-zone soils.
Therefore, Alternative 4 would achieve the best treatment of soils that are continuing to
contaminate the groundwater. In addition, Alternative 4 includes treatment of lead- ..
, contaminated groundwater at ST13 and DP26.
Alternative 5 includes selective excavation of soils, but large volumes of contaminated soils
cannot be excavated because of the presence of pipelines, tanks, and operating systems in
the area. In addition, Alternative 5 does not address the significant contamination
remaining in the smear-zone soils. Under Alternative 5, the remaining soil contamination is
allowed to slowly move through the soil to the groundwater, where it would be pumped
out and treated. '
,-
Alternative 3 addresses petroleum contamination in soil and, to a lesser extent, in smear-
zone soils. However, at STlO and SS 14 Alternative 3 treats an area one-tenth the extent of
the soils that Will be treated using Alternative 4. In addition, because Alternative 3 does not
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include groundwater treatment, groundwater contaminants, including lead, will remain
significantly longer than estimated for Alternatives 4 and 5.
None of the contaminants are addressed by Alternatives I and 2 except through natural
processes. Therefore, Alternatives I and 2 provide the least long-tenn effectiveness and
permanence. . .
8.4 Reduction of Toxicity. Mobility. or Volume Through Treatment
Alternatives 4 and 5 result in the greatest reduction in toxicity, mobility, and volume of
contamination by removing and/or tteating contamination in the soil and above and in the
groundwater. Alternative 4 also reduces the volume of lead-contaminated groundwater at
ST13 and DP26. Alternative 4 aggressively tteats the source of groundwater contamination
by remediating the subsurface soils; including those in the smear zone.
Alternative 5 does not redu~ the soil contamination as effectively, but would include more
aggressive groundwater extraction and' treatment
Alternative 3 does not reduce or treat the soil contamination, sPecifically that in the smear-
zone soils, as effectively as Alternative 4. In addition, Alternative 3 does not reduce or treat
the groundwater contamination. .
Neither Alternative 1 nor 2 reduces the toxicity, mobility, or volume of the contaminants
through treatment
8.5
Short- Term Effectiveness
None of the alternatives are expected to pose an unacceptable risk to residents or workers
during implementation. All potential impacts from construction and system operation will
be readily conttolled using standard engineering controls and practices.
Alternative 4 is expected to clean: the soils, including the smear zone, in the shortest amount
of time, thus eliminating the source of groundwater contamination. In. addition, by treating
lead contamination in the groundwater, Alternative 4 reduces the time necessary to achieve
groundwater cleanup standards.
Alternative 5 requires much more time than Alternative 4 to achieve soil cleanup because of .
the impracticability of excavation for the removal of all the contaminated soils, especially.
those in the smear zone above the groundwater. Though Alternative 5 includes more
extensive groundwater extraction and treatment, it is questionable whether groundwater
treatment can achieve cleanup standards faster than natural processes because of the large
amounts of remaining soil contamination that would continue to contaminate the
groundwater.
Alternative 3 includes some treatment of soil contamination, but does not address
contamination in the smear zone or in the groundwater. Therefore, Alternative 3, as well as
Alternatives 1 and 2, depends on natural processes to achieve groundwater cleanup
standards. Using only natural processes, groundwater contamination may persist for more
than 200 years. .
8.6
Implementability
All alternatives use readily available technologies and are feasible to consttuct Alternatives
1 and 2 are readily implementable because they require no additional action other than
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monitoring and/or institutional controls. The technology described in Alternative 3 is
relatively limited in scope and is readily irnplementable.
The success of removing petroleum products on tOp of the groundwater as part of
, Alternatives 3, 4, and 5 depends on the amount of petroleum product that flows into the
collection system. Effective collection of petroleum is difficult with the thin layers of
petroleum products and the large fluctuations in groundwater levels found at Eielson AFB.
The technologies included in Alternative 4 for the removal of petroleum contamination are
being implemented at three other fuel-contaminated areas at Eielson AFB. The results to
date have been encouraging. These technologies appear to be the most effective method for
treating the smear-zone soils on top of the groundwater, where much of the residual
petroleum contamination remains.
Alternative 5 would be poor in effectiveness and implementability because it is not possible
to excavate large volumes of contaminated soil near pipelines, tanks, and operating
sy~tems, nor in the smear-zone $oil. Furthermore, although groundwater extraction and .
treatment is a commonly used technology, its effectiveness in ~chieving groundwater
cleanup standards is not well established. EA (1994) has shown that skimming has not
been proven effective at other sites at Eielson AFB with similar thickness of floating
product.
8.7 Cost
On the basis of the information available at the time the alternatives were developed. the
estimated cost for each alternative is presented in Table 31. The cost estimates are order-of-
magnitude estimates with an intended acc~cy' of +50% and -30%. The accuracy limits are
based on EPA (1988) guidance. '
The cost estimates should only be used for comparison between alternatives, and not for
comparisons with other facilities, especially if the othe~ sites are in the lower 48 states
where costs are lower. Cost estimates, both capital and operations and maintenance, are
elevated due to 1) Alaska labor rates that are 30% higher, and 2) major equipment costs that
are 25% higher. Materials costs were estimated to be comparable with those in the lower
48 states.
.
The estimated costs for the implementation of Alternative 4 listed in Table 31 have been
revised downward since the development of the OU2 Proposed Plan (U.S. Air Force
, 1993i) and completion of the public comment period The initial construction cost estimate
for Alternative 4 was $5,150,000 for STI0 and SS14 and $3,500,000 for ST13 andDP26.
The total cost estimate for Alternative 4 was $7,400,000 for STIO and SS14 and
$12,500,000 for ST13 and DP26. In addition, the revised costs are'better constrained than
those calculated and reported'in the OU2 Proposed Plan. The cost revision is based on
recent results from Eielson AFB onsite experience with cleanup activities. Recent Eielson
AFB site experience indicates that remedial technologies can be implemented at a lower,
capital cost than that calculated in the OU2 FS (U.S. Air Force 1993d) without changing
the basic remedial technologies and still achieving the remedial goals listed in Tables 27 and
28. The revised costs are discussed in detail in Section 11 of this ROD. '
8.8 State Acceptance
The state of Alaska concurs with the actions proposed in this ROD. The following non-
CERCLA actions, although outside this ROD, have been projected to occur:
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TABLE 31. Cost 01 Remedial Alternatives (thousands 01 dollars)(a)
Type 01 Cost Alternative 2 Alternative 3 Alternative 4 Alternative 5
Restricted Bioventing Bioventing/Soil Vapor. Soil Excavation/
Groundwater Use Extraction/ Groundwater
Air Sparging/Skimming/ Treatment(c)
Groundwater Treatment
(ST13 and DP26 only)
(b.c)
ST10: Bulk Fuel Storage
SS14: Railroad JP-4 Fuel Spill Area.
Construction 5 620 1,700 2,900 (1,600)
otal(d) 1,170 2,100 3,000 9,100 (6,600)
ST13: Diesel Fuel Spill
DP26: Fuel Tank Sludge Burial
!construction o. 830 2,200 (1,200) 1,750 (1,400)
trotal 1,170 5,800 10,700 (7,100) 10,700 (8,900)
(a) Cost estimates are order-of-magnitude; use only for comparison among alternatives.
iAlternative 1 has no associated costs.
(b) Soil venting, air sparging, and groundwater treatment at ST13 and DP26. Soil venting and
lair sparging only at 5T10 and 5514.
(c) Costs in parentheses are for the. groundwater treatment component.
(d) Assumes. 5% annual inflation over operational life of remediation. The difference between
his value and Construction costs represents Operation and Maintenance costs.
.
The two 25,OOO-gallon underground storage tanks at ST18 will be removed in
accordance with 18 MC 78, Underground Storage Tank Regulo.tions. Removal is
planned for 1995. .
In a continuing effort to minimize th~ risks associated with exposure to contaminated
groundwater and to control additional plume migration, dewatering efforts associated
with ongoing base activities will be coordinated with the State of Alaska in accordance
with 18 MC 72, Wastewater Disposal Regulo.tions.
.
. 8.9 Community Acceptance
Community response to the actions proposed in this ROD were generally positive. Only a
few public comments were received that questioned some facets of the Proposed Plan.
These comments and responses to them are discussed in the fmal part of this ROD, the
Responsiveness Sunimary.
9.0
The Selected Remedy
The cumulative risks for STll are within acceptable regulatory levels. .An environmental
cleanup is not proposed at this site.
The cumulative risks for ST18 are within acceptable regulatory levels. Environmental
cleanup is not proposed under Superfund. However, under the Underground Storage
Tank Program, the U.S. Air Force will remove the tanks at ST18. If the drywell at ST18
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can be located and can be removed without damaging the existing structures, it will be
removed. Confmnatory soil samples will be collected ,in either case.
No environmental cleanup is proposed for ST19, even though groundwater concentrations
at levels approximately two times the MCLs for benzene and toluene were found in one
. monitoring well (19-02A) located approximately. 150 feet from the spill area. Fate and
transport modeling conducted for this area indicate that benzene and toluene concentrations
have been and will continue decreasing. Using conservative modeling assumptions, the
modeled peak concentration for ethylbenzene is estimated to be approximately 900 Jlg/L
and, therefore, may exceed its MCL of 700 J..lg/L at some time in the future. Xylene
concentrations are not expected to exceed the MCL.
Soil and groundwater sampling results and the fate and transport modeling both indicate
that the contamination at ST19 is restricted to a limited area (approximately 2 acres) directly
adjacent to the spill area and that the weathered petroleum contamination in subswface soils
is not expected to act as a significant continuing source of groundwater contamination.
Groundwater concentrations in wells located downgradient within 1,000 feet of the spill
area do not exceed MCLs. In addition, ST19 is located in a ~mote area of the base that is
not likely to be used for residential purposes in the foreseeable future. Given the low level
of residual contamination present and the limited area impacted, no remedial action will be
taken at STI9. Institutional controls (e.g., command directives and protective covenants)
will be established to prevent the use of groundwater at ST19 and the groundwater will
continue to be moniWred to verify the results of the fate and transport modeling and to
ensure protectiveness of human health and the environment
Source areas STlO, SSI4, ST13, and DP26 will require cleanup. Based upon
consideration of the requirements of CERCLA, the detailed analysis of the alternatives
using the nine criteria, and public comments, the U.S. Air Force, ADEC, and EP A have
detennined that Alternative 4 is the most appropriate remedy for both sets of sites. Major
components of the selected remedy include:
.
Install an active skimming system to remove fuel floating atop the groundwater at ST13
and DP26, where the product is sufficiently mobile tO,be recoverable.
Install passive skimming systems to remove fuel floating atop the groundwater and to
prevent fuel from seeping into Hardfill Lake at STIO and SS14, where the product is
sufficiently mobile to be recoverable. '
.
.
Install a bioventing and SVE system to remediate sQil contamination that poses a threat
to groundwater through leaching. This system may include air sparging within the
upper part of the groundwater table and the smear zone to volatilize and promote
bioremediation of the contaminants. This entire system is also anticipated to reduce fuel
floating atop the groundwater. '
Install groundwater extraction and treatment facilities in areas of highest groundwater
lead concentrations at ST13 and DP26. The physica1lchemical treatment of the '
groundwater includes precipitation of metals and air stripping of volatile organic
compounds. '
.
.
Monitor groundwater at ST19, STlO, SSI4, ST13, and DP26 to evaluate contaminant
l~vels and migration until remediation levels' are achieved.
Monitor the distal end of the contaminant plume at ST13 and DP26 to evaluate if the
plume is expanding. Monitoring will continue for 5 years, at which time the need for
.
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further monitoring will be reevaluated. Hydraulically contain the groundwater plume at
STl3 and DP26 by extracting groundwater from near the plume's distal end, if the
plume is expanding. The groundwater extracted from the hydraulic containment well
will be treated in the physical/chemical system. .
Notify the regulatory agencies of proposed dewatering activities, and evaluate their
potential for impacting areas of groundwater contamination- . .
.
.
Remove the drywell south of ST18 and test soils for contamination, if it can be located
and removed without damaging the existing structures. If the drywell cannot be
located, conduct confmnatory sampling.
Monitor the groundwater near STl1, ST18, and selected SER sites, including SS31, to
. verify that contaminant concentrations, if any, remain within acceptable ~ning
levels. Monitoring will continue for 5 years, at which time the need for further
monitoring will be reevaluated.
.
.
Implement institutional controls to prevent exposure to contaminated groundwater. In
the event of base closure, any remaining contaminated sites will be addressed in
accordance with CERCLA Section 120.
Perform supplemental soil sampliIig during 1994 in the vicinity of Building 6214
(STI6) during 1994 to confirm that no significant contamination remains.
.
Alternative 4 achieves substantial risk reduction through treatment of the principal sources
of groundwater contamination-fuels on top of the groundwater and soil contamination.
Groundwater monitoring and institutional controls will continue in both areas to restrict the
use of groundwater. Hardfill Lake will prevent expansion of the plume at STlO and SS14
because contamination entering the water evaporates at the surface. The lead in the
groundwater at ST13 and DP26 will be actively treated by a groundwater extraction.
system. BlEXs in groundwater will be expected to diminish due to removal of the source.
The goal of this remedial action is to restore groundwater to its beneficial use within a time- .
frame that is reasonable given the particular circumstances of the site. Based on
information obtained during the RI and on a careful analysis of all remedial alternatives,
U.S. Air Force, state of Alaska, and EP A believe that the selected remedies will achieve
.this goal. . .
I.
It may become apparent, during implementation or operation of the groundwater extraction
system and its modifications at ST13 and DP26, that lead levels have ceased to decline and
are remaining constant at levels higher than the remediation goals over some portion of the
contaminated plume. In such a case, the system performance standards andlor the remedy
may be evaluated. Groundwater contamination may be especially persistent in the
immediate vicinity of the contaminants' source, where concentrations are relatively high.
. The ability to achieve final remediation goals at all points throughout the area of attainment,
or plume, cannot be determined until the extraction system has been implemented and
modified as necessary, and plume response monitored over time. If the selected remedy
cannot meet the final remediation goals, at any or all of the monitoring points during
implementation, the contingency measures (bulleted below) and goals described in this
section may replace the selected remedy and goals for these portions of the plume. Such
contingency measures will, at a minimum, prevent further migration of the plume and
include a combination of containment technologies and institutional controls. These
measures are considered to be protective of human health and the environment, and are
technically practicable under the corresponding circumstances.
. -
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The selected remedy will include groundwater extraction for an estimated period of 5 years,
dependent upon review, during which time the system's perfonnance will be carefully
monitored on a regular basis and adjusted as warranted by the perfonnance data collected
during operation. Modifications may include any or all of the following:
.
pulse pumping to allow aquifer equilibration and encourage adsorbed contaminants to
partition into groundwater
installation of additional extraction wells to facilitate or accelerate cleanup of the
contaminant plume.
.
To ensure that cleanup goals continue to be maintained, the aquifer will be monitored where
p~ping has ceased. Monitoring will be conducted on an annual basis, dependent upon
review.
, The remediation will be implemented with a phased approach, where ongoing monitoring
will evaluate the, perfonnance of each technology before proceeding to the next phase of
cleanup. Because the principal focus of the cleanup is the remediation of floating fuel and
VOC-contaminated soils, much of monitoring will focus on the capillary fringe and
unsaturated zone. The phased approach will allow the U.S. Air Force to use field data
during cleanup to get the best mix of technologies to meet cleanup objectives. 'The costs
included in Table 31 are conservative because it was assumed that all components of the
system will be required. If some of the components are not required, the actual costs may
be significantly lower:
The underground fueling system at ST13 and DP26 is scheduled for replacement in 1994.
An estimated 12,000 cubic yards of soil will be excavated during this replacement; of this
volwne, 7,000 cubic yards are believed to be contaminated. These soils are among the
most contaminated at the site, and they will be treated as part of the construction project
, The selected remedy for ST13 and DP26 may be affected by this project and may have to
be reevaluated after the excavation and soil treatment is completed.
10.0
Statutory Determinations
, . The selected remedy meets statutory requirements of Sectiori 121 of CERCLA, as amended
by SARA, and to the extent practicable, the NCP. The evaluation criteria are discussed
below. ,
10.1 Protection of Human Health and the Environment
.
The selected remedies protect human health and the environment through the removal of the
principal sources of groundwater contamination and the extraction and treatment of lead- .
contaminated groundwater (ST13 and DP26 only). VOC-contamin:lted groundwater will
be reniediated through removal of the source of continuing groundwater contamination.
During the cleat)up, institutional controls will eliminate the threat of exposure t9
contaminated groundwater.
The two principal sources of groundwater contamination are floating fuel and VQC-
contaminated soils. The floating fuel will be removed by vapor extraction, bioventing, air
sparging, and passive removal (STIO and SSI4) or active skimming (ST13 and DP26);
soil contamination will be removed by vapor extraction, bioventing, and air sparging.
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Removal of the source of VOC-contaminated groundwater and extraction and treatment of
the lead-contaminated groundwater (ST13 and DP26 only) will eliminate the threat of
exposme to these contaminants from ingestion and inhalation of groundwater. The BLRA
(U .S. Air Force 1993c) estimated a reasonable maximum exposure risk for residential land-
use from these exposure pathways at 2 x 10-3 for carcinogenic risk with a HI of 4 for
noncarcinogenic risks at STlO and SSI4; the estimate forST13 and DP26 is 5x 10-4 for
carcinogenic risk and a HI of 3 for noncarcinogenic risk. Once the [mal remediation goals
are achieved, the cancer risks, for all sites, will be reduced to 9 x 10-6 and the HI will be
reduced to 2-
10.2. Attainment of Applicable or Relevant and Appropriate Requirements
of Environmental Laws (ARARs)
The selected remedies will comply with ARARs of federal and state of Alaska
environmental and public health laws. .
10.2.1 Applicable or' Relevant and Appropria.te Requirements (ARA~s)
. .
The remedy chosen for each set of sites will comply with all action-, chemical-, and
location-specific MARs. The ARARs are listed in the following sections, and the
relationship between them and the five remedial alternatives are listed in Table 29.
10.2.1.1 Action-Specific
Remedial treatment activities will meet the following action-specific ARARs
.
state of Alaska Solid Waste Management Regulations (18 AAC 60) for disposal of
treated soils .
.
state of Alaska Wastewater Disposal Regulations (18 AAC 72) for the discharge of
industrial wastewater
.
state of Alaska Hazardous Waste Regulations (18 AAC 62), for the treatment and
disposal of hazardous wastes
RCRA waste standard 40 CPR 268 Land Disposal Restrictions may be applicable if
placement of RCRA hazardous wastes occurs .' .
.
.
RCRA waste standards 40 CFR 264.251, which specify that waste piles must use a
single liner and leachate collection system
Federal Clean Air Act (42 USC 7401), as amended, in the case of venting of
contaminated vapors
.
Federal A WQC ~ 304 and state of Alaska Water Quality Standards (18 AAC 70) for
discharges into Garrison Slough (column 4 of Table 32).
10.2.1.2 Chemical-Specific .
Remedial treatment activities will meet the following chemical-specific ARARs:
.
.
MCLs and maximum contaminant level goals (MCLs, non-zero maximum contaminant
limit goals [MCLGs], and action levels) established under the Safe Drinking Water Act
for groundwater that may be used for drinking water supply (40 CFR 141 and 18
AAC 80). These ARARs are listed in column 2 of Table 32.
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.
Alaska Water Quality standards for Protection of Class (l)(A) Water Supply, Class
(l)(B) Water Recreation, and Class (1)(C) Aquatic Life and Wildlife (18 AAC 70)
Hardfill Lake is an old gravel pit, excavated to a depth below the
groundwater table. The lake is within the STIO and SS 14 source areas and
serves as a barrier against migration of contamination out of the immediate
area. After closeout ofSTlO and SS14, Hardftll Lake will be protected in
accordance with Alaska Water Quality Standards.
.
Alaska Oil Pollution Regulations (18 MC 75)
Under the Alaska Oil Pollution Regulations, responsible parties are required
to clean up oil or hazardous releases. The U.S. Air Force anticipates
achieving a cleanup level that is consistent with this regulation and has
proposed a calculation of soil cleanup levels based on the findings in the
, BLRA (U.S. Air Force 1993c) and a methodology using the'EPA SESOIL
TABLE 32. Chemical-Specific ARARs for Chemicals of Concem
Chemical Compound Groundwater Surface Water Soil( a)
( 1 ) (2) (3) (4) (5)
Drinking Ava Awa::. ,Alternative
Water Aquatic Life Human Health Cleanup levels for
MCL Freshwater Fish Consumption Petroleum
(~g/l) Chronic (~g/L) Contaminants
(llo/L) (l1o/ko)
Benzene 5 S300(b) 40 0.2
rToluene, 1000 17.500(b) 424,000 80
Ethylbenzene 700 32.000(b) '3,280 140
)(vlenes 10,000 ,760 ",
'Japhthalene 620
..ead 1S(c) 1.3
(a)Soil cleanup levels were established to protect groundwater from leachate. The model used to
::alculate these values is from Anderson (1992).
(b) Freshwater acute criterion, there is no freshwater chronic criterion for, these compounds.
(c)EPA has established an action level of 15 !.lolL for lead in drinkina water.
and AT.l23D mOdels (Anderson 1992). The proposed soil cleanup levels
are based on protecting groundwater in accordance with drinking water
standards.
.
Alaska Regulations for Leaking Un~erground Storage Tanks (18 AAC 78)
Under the Alaska regulations for remediation of contaminated soils and the
regulations for cleanup of petroleum releases from underground storage
tanks, the ADEC regional supervisor has the authority to detennine the level
of cleanup that is appropriate for site-specific conditions. The regional
supervisor may identify alternative cleanup standards based on the potential
for leaching to groundwater. In accordance with this requirement,
alternative soil cleanup standards have been calculated (column 5 of Table
28) based on the f"mdings in the BLRA (U.S. Air Force 1993c) and a
-------
OU-2 Record of Decision
Eielson Air Force Base
methodology using the EP A SESOIL and A T123D models (Anderson
1992). The soil cleanup levels are based on protecting groundwater in
accordance with drinking water standards (Appendix D of the BLRA [U.S.
Air Force 1993c D.
10.2.1.3
None.
Location-Specific
10.2.2
Information To-Be-Considered
The following infonnation to-be-considered will be used as a guideline when implementing
the selected remedy:
.
state of Alaska Interim Guidance for Non-UST (underground storage tank)
Contaminated Soil Cleanup Levels (July 17, 1991)
state of Alaska Guidance for Storage, Remediation, and Disposal of Non-UST
Petroleum Contaminated Soils (July 29,1991)
.
.
state of Alaska Interim Guidance for Surface and Groundwater Cleanup Levels
(September ~6, 1990). .
10.3
Cost Effectiveness
The selected remedy is cpst effective because it has been detennined to provide overall
effectiveness propo~oi1ate to its costs and duration for remediation of the contaminated -
soils and groundwater. Although the 30-year present worth of $3,000,000 for ST10 and
SS14 and $10,700,000 for ST13 and DP26 is greater than Alternatives 1,2, and 3, the
benefits for Alternative 4 include 1) aggressive treatment of the source of groundwater
contamination through implementation of SVE and air sparging systems, 2) it addresses a
larger area of contamination, 3) it includes active skimming of floating fuel and
groundwater treatment at ST13 and DP26, and 4) it is expected to require less time to meet
[mal remediation goals than these other alternatives because it treats a larger source volume.
. These remedial actions will actively reduce the source of VOC-contaminated groundwater.
Alternative 4 is less. expensive than Alternative 5 at both sets of sites. Alternative 4 is cost
effective because 1) it is expected to require less time to meet final remediation goals, 2) it
treats a larger area of soil contamination, 3) it uses an equally comprehensive approach for.
the removal of floating fuel, and 4) Alternative 5 is not readily implementable because it
may require demolition of existing fuel delivery systems.
Alternative 5 requires excavation and treatment of VOC-contaminated soils. Limited
amounts of contaminated soils are available for excavation because of the existing fuel-
delivery infrastructure whose current and future activity is required to fulfill Eielson AFB's
primary national security missiori.- At ST10 and SS14, Alternative 4 would remediate an
estimated 120,000 cubic yards of soil; Alternative 5 would excavate an estimated 6,700
cubic yards of soil. At ST13 and DP26, Alternative 4 would remediate an estimated
47,000 cubic yards 9f soil; Alternative 5 would excavate an estimated 660 cubic yards of
soil.
. Alternative 5 would only use active skimming for the removal of floating fuel, and it is
estimated that 50% or less of this material can be extracted with this technology.
-------
OU-2 Record of Decision
Eielson Air Force Base
Alternative 4 would not only include skimming (active and passive), but it would also use
bioventing, SVE, and air sparging to enhance the remediation of the floating fuel layer.
A complete excavation of the contaminated subsurface soils within the smear zone was
proposed as an alternative in the draft OU2 FS (U.S. Air Force 1992) for both set of sites.
In order to effectively remediate the source of groundwater contamination, irwas assumed
that all structures at the four sites would be demolished. A detailed analysis for these
alternatives were conducted, and the estimated minimum cost for STIO and SS14 was
$39,000,000; the estimated minimum cost for ST13 and DP26 was $16,100,000.
Because of the high estimated costs and the requisite demolition of active fuel delivery
systems, these excavation alternatives were not considered implementable, and the scope of '
excavation was reduced for the final OU2 FS (U.S. Air Force 1993d).,
The remedial systems that will be implemented in Alternative 4 will be implemented in
phases, based on actual conditions observed in the field through the monitoring of
groundwater, VOC-contaminated soils, and the floating fuel layer. The estimated costs for
the implementation of Alternative 4 have been revised downward since the development of ,
the OU2 Proposed Plan and completion of the public comment period (Table 33).' The
initial construction cost estimate for Alternative 4 was revi~ from $5,150,000 to
$1,700,000 for STIO and SSI4; it was revised from $3,500,000 to $2,200,000 for ST13
and DP26. The total cost estimate for Alternative 4 was revised from $7,400,000 to
$3,000,000 for STIO and SSI4; it was revised from $12,500,000 to $10,700,000 for
, ST13 and DP26. In addition, the revised costs are better constrained than those reponed in
the Proposed Plan (U.S. Air Force 1993i). The revi$ed costs are discussed in Section 11.0
of this ROD. This revision is based on recent results from Eielson AFB onsite experience
with cleanup activities. Recent Eie1s9n AFB site experience indicates that remedial
technologies can be implemented at a lower capital cost than that calculated in the OU2 FS
(U.S. Air Force 1993d) without changing the basic remedial technologies and still
achieving the remedial goals listed in Tables 27 and 28. '
10.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable
The U.S. Air Force, the state of Alaska, and EP A have determined that the selected
remedies represent the maximum extent to which permanent solutions and treatment
technologies can be used in a cost-effective manner at the OU2 sites. Of those alternatives
that are protective of hwitan health and the environment and comply with ARARs, the U.S. '
Air Force, the state of Alaska, and EP A have determined that the selected remedies provide
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.
Alternative 4 would aggressively treat the source of VOC groundwater contamination,
VOC-contaminated subsurface soils, and floating fuel. The VOC-contaminated
groundwater would be allowed to remediate by source reduction; lead contamination will
be actively remediated by extraction and treatment Alternative 5 would remediate the soil
contamination by removal and treatment; however, it will not treat as large a'volume of
soil. Large volumes of contaminated soils could not be excavated because of existing base
fuel storage and delivery systems. The remaining soil contamination would be allowed to
slowly mo~e through the soil to the groundwater, where it would be pumped out and
treated. Alternative 5 would remove floating fuel only through active skimming, an option
that is unlikely to remove more than half of this material. Furthermore, although
, ,
,-
-------
OU-2 Record of Decision
Eielson Air Force Base
groundwater extraction and treatment is a commonly used technology, its effectiveness in
achieving groundwater cleanup standards is not well established.
Alternatives 4 and 5 would result in the greatest reduction in toxicity, mobility, and volume
of contamination by treating or removing VOC-contaminated soils and floating fuel.
Alternative 4 is expected to be more effective. However, Alternative 4 does not actively
treat VOC-contaminated groundwater, except for lead-contaminated groundwater at ST13
. and DP26. Alternative 5 does actively reduce VOC-contamination through extraction and
treatment. Alternatives 1 through 3. do not treat the source of groundwater contamination as
aggressively as Alternatives 4 and 5. All alternatives rely on Hardfill Lake to prevent
migration of the groundwater contamination at STI0 and SS 14; the volume of the
groundwater plume at STI3. and DP26 will be monitored.
Alternative 4 would be expected to cleanup the soils in the shortest amount of time, thus
eliminating the source of groundwater contamination. In addition, by treating lead
contamination in the groundwater at STI3. and DP26, Alternative 4 will reduce the time
necessary to achieve groundwater cleanup standards. Alternative 5 would require much
more time than Alternative 4 to achieve soil cleanup because of the inability to excavate all
of the contaminated soils. Although Alternative 5 would include more extensive
groundwater extraction and treatment, it is questionable whether groundwater treatment
would be able to achieve cleanup standards faster than natural processes because of the
large amounts of remaining soil contamination that could continue to contaminate the .
groundwater. Alternatives 1,2, and 3. would provide much less short-tenn effectiveness
than the other alternatives.
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. The technologies in Alternative 3. are relatively limited in scope and would also be
readily implementable. Several of the technologies in Alternative 4 for the removal of
petroleum contamination (bioventing, SVE, and skimming) are being implemented at three
other fuel-contaminated areas at Eielson AFB. The results to date suggest that two of the
technologies are effective, bioventing (Battelle 1994) and SVE (EA 1994). Skimming for
fuel has only been successful at one of four demonstrations (EA 1994). Alternative 5
would be difficult to implement effectively because it is not possible to excavate large
volumes of contaminated soils near pipelines, tanks, or operating systems.
, .
The most d~ive factors ii1 th~ selection decision were long-term effectiveness and
implementability. Alternative 4 provides the best option for effective remediation of STlO,
SSI4, STI3., and DP26 in light of the constraints presented by'active base fuel supply
operations. . .
10.5 Preference for Treatment as a Principal Element
By treating the source of VOC-contaminated groundwater and actively treating lead-
contaminated groundwater (STI3. and DP26 only), the selected remedies address the
principal source of threats posed by the sites through the use of treatment technologies.
Therefore, the statutory preference for remedies that employ tre$nent as a principal
element is satisfied.
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OU-2 Record of Decision
£ielson Air Force Base
11.0
Explanation of Significant Differences
The estimated costs for the implementation of Alternative 4 have been revised downward
since the development of the OU2 Proposed Plan (U.S. Air Force 1993i) and completion
of the public comment period. The initial construction cost estimate for Alternative 4 was
revised from $5,150,000 to $1,700,000 for ST10 and SSI4; it was revised from
$3,500,000 to $2,200,000 for ST13 and DP26. The total cost estimate for Alternative 4
, was revised from $7,400,000 to $3,000,000 for STlO and SSI4; it was revised from
$12,500,000 to $10,700,000 for ST13 and DP26. In addition, the revised costs are better
constrained than those calculated in those reported in the OU2 Proposed Plan. This
revision is based on recent results from Eielson AFB onsite experience with cleanup
3:ctivities. Recent Eielson AFB site experience indicates that remedial technologies can be
implemented at a lower capital cost than that calculated in the OU2 FS (U.S. Air Force
, 1993d) without changing the basic remedial technologies and still , achieving the remedial
goals listed in Tables 27 and 28. '
The revised costs were calculated using the same methodologies and contingencies as those
in the FS (U.S. Air Force 1993,d) that are reponed in Table 3~. of this ROD.
Recent field experience indicates that bioventing will be more effective in remediation than,
was initially assumed during the preparation of the OU2 fmal FS and Proposed Plan.
Thus, bioventinglSVE will be the primary remedial technologies. If these systems do not
prove to be effective in attaining final remedial goals, then an air sparging system may be
implemented as pan of the phased approach. The updated cost estimate retained the
implementation of air sparging as a contingency. Its scope, however, is greatly reduced.
The updated cost estimate assumes that air sparging will be implemented where the ,
apparent thickness of floating product exceeds I foot This reduces the number of wells at
ST10 and SS 14 from 350 to 60. The number of wells at ST13 and DP26 is reduced from
15 to 4.
, Additional changes in assumptions that went into these new calculations for capital costs
are
. no treatment of gases extracted by the SVE system
. deletion of a second control building
. deletion of the asphalt cap
. ' no hydraulic containment for groundwater at ST13 and DP26
. reduction in well costs from $2000 to $1500 per well.
The primary changes in operations and maintenance costs are
no maintenance of asphalt cap
no maintenance of hydraulic containment at ST13 and DP26
groundwater monitoring at ST10 and SS14 will cease after 10 years, once remediation
is complete.
The assumptions for several of these changes are
-------
OU-2 Reccrd of Decision
Eielson Air Force Base
The resulting costs listed in this section are lower than those initially calculated and reported
in the Proposed Plan (U.S. Air Force 1993i); thus, the selected remedies are even more
cost effective than originally estimated.
12.0
References
Anderson. 1992. Development of Generic Soil Cleanup Levels Based on Analysis of the
Leachate Pathway. Environmental a~up Division, Oregon Department of Environmental
Quality, May 12. .
Battelle. 1992. Remedial Investigation/Feasibility Study -- Operable Units 3. 4. and 5
Management Plan. Eielson AIr Force Base. Alaska. Battelle, Environmental Management
Operations, Richland, Washington (Final).
Battelle. 1994. Bioremediation of Hazardous Wastes at CERCLA and RCRA Sites:
Eielson APE Site. Project Report, Battelle, Columbus, Ohio. .
Cederstrom, DJ. 1963. Ground-Water Resources of the Fairbanks Area. Alaska. U.S.
Geological Survey Water-Supply Paper 1590.
Clement Associates. 1988. Comparative Potency A.pproach for Estimating the Cancer
Risk Associated with Exposure to Mixtures of Polycyclic Aromatic Hydrocarbons.
Interim Final Report, Clement Associates, Fairfax, Virginia.
CH2M HilL 1982. Installation Restoration Program Records Search for Eielson Air Force
Base. Alaska. CH2M Hill, Gainesville, Florida.
Dames and Moore. 1985. Installation Restoration Program Phase IT -
ConfinnationlQuantification Stage 1 First Draft Report for Eielson Air Force Base. Alaska.
Alaskan Air Command. Prepared by Dames & Moore for the U.S. Air Force Occupational
and Environmental Health Laboratory, Brooks Air Force Base, Texas, February 28.
EA 1994. "OUIB Interim Remedial Action, Outline Summary of Work at Source Areas
ST-20 (B-7), ST-20 (E-9), ST-48, ST-49, and SS 50-52 during 1991 and 1993." Letter
Report, EA Engineering, Science~ and Technology, February 25, 1994.
Eielson AFB. 1992. Eielson Air Force Base Comprehensive Landuse Plan. Eielson Air .
Force Base, Fairbanks, Alaska. .
EPA 1984. "Summary of Current Acceptable Daily Intakes (ADIS) for Oral Exposure."
Environmental Criteria and Assessment Office, Cincinnati, Ohio.
I .
I
EPA 1988~ Guidance for Conducting Remedial Investigations and Feasibility Studies
under CERCLA OSWER Directive 9355.3-01, U.S. Environmental.Frotection Agency,
Office of Emergency and.Remedial Response, Washington, D.C. (Interim Fmal)..
EPA. 1991a. Supplemental Guidance for Superfund Risk Assessments in Region 10.
U.S. Environmental Protection Agency, Seattle, Washington.
I .
-------
OU-2 Record o( Decision
Eie/son Air Force Base
EPA. 1991b. Health Effects Assessment Summary Tables. PB91-921199, U.S.
Environmental Protection Agency, National Technical Information Service, Springfield,
Virginia.
EPA. 1992a. Health Effects Assessment Summary Tables. NTIG/PB92-92 1 199, U.S.
Environmental Protection Agency, National Technical Information Service, Springfield,
Virginia. .
EPA. 1992b. Integrated Risk Information System (IRIS) (Online). U.S. Environmental
Protection Agency, Office of Health and Environmental Assessment, Environmental
Criteria and As$essment Office, U.S. Environmental Proteetion Agency, Cincinnati, Ohio.
EPA, ADEC, and U.S. Air Force. 1991. Eielson AFB Federal Facility Agreement under
CERCLA Section 120, EPA Docket Number: 1089-07-14-120.
HLA 1989; Installation Restoration Program Remedial InvestigationIFeasibility Study.
Stage 3. Eielson Air Force Base. Draft Remedial Investigation/Feasibility Study. V~lume IT
(July 1988 to April 1989), 'Harding Lawson Associates. ' ,
HLA. 1990. Installation Restoration Program Remedial InvestigationlFeasibility Study.
Stage 4. Draft Remedial InvestigationIFeasibility Study. Volumes I throu~h V. Harding
Lawson Associates, Anchorage. Alaska.
~~ ii5~I~~~~~~~nl~:::~~~~~!s~~e~~~I~~~:~a~n:;:~~I~dY,
Harding Lawson Associates, Anchorage, Alaska.
Krumhart, A P. 1982. Hydrologic Information for Land-Use Planning. Badger Road
Area. Fairbanks. Alaska. Water-Resources Investigation 82-4097. U.S. Geological
Survey. '
Nelson, G. 1978. Hydrologic Information for Land-Use Planning. Fairbanks Vicinity.
Alaska. U.S. Geological Survey. '
SAIC. 1989. U.S. Air Force Installation Restoration Program Remedial
InvestigationIFeasibility Stu~y of the Fuel Saturated Area at Eielson Air Force Base.
Alaska: Remedial Investigation Report. Volumes I, II, andID. Science Applications
" International Corporation (Draft). '
U.S. Air Force. 1992. Eielson Air Force Base OU-2 Remedial InvestigationIFeasibility
. Study: Baseline Risk Assessment Battelle, Environmental Management Operations,
Richland, Washington (Draft).
U.S. Air Force. 1993a. Eielson Air Force Base OU-2 Remedial InvestigationlFeasibility
Study: Remedial Investigation Report. Battelle, Environmental Management Operations,
Richland~ Washington (Final)..
U.S. Air Force. 1993b. Eielson Air Force Base OU-2 Remedial IrivestigationlFeasibility
Study: Remedial Investigation Ap,pendixes. Battelle, Environmental Management
Operations, Richland, Washington (Final).
U.S. Air Force.. 1993c. Eielson Air Force Base OU-2 Remedial InvestigationIFeasibilit;y
Study: Baseline Risk Assessment Battelle, Environmental Management Operations,
Richland, Washington (Final).
-------
OU-2 Recon:J of Decision
Eiefson Air Force Base
U.S. Air Force. 1993d- Eielson Air Force Base OU-2 Remedial InvestigationlFeasibility
Study: Feasibility Study. Battelle, Environmental Management Operations, Richland,
Washington (Final).
U.S. Air Force. 1993e. Background Soil Quality. Eielson Air Force Base. Alaska.
Banelle, Environmental Management Operations, Richland, Washington (Final).
U.S. Air Force. 1993f. Background Groundwater Quality. Eielson Air Force Base.
Alaska. Battelle, Environmental Management Operations, Richland, Washington (Final).
. .
U.S. Air Force. 1993g. Source Evaluation Report. Phase 1. Eielson Air Force Base.
Alaska. Battelle, Envirorimental Management Operations, Richland, Washington (Fina-U.
U.S. Air Force. 1993h. Site Groundwater Management Plan. Eielson Air Force Base.
Alaska. Battelle, Environmental Management Operations, Richland, Washington (Draft).
U.S. Air Force. 1993i. Proposed Plan for Operable Unit 2 and Other Areas. . Battelle,
Environmental Management Operations, Richland, Washington (Final). .
.~~~~~~k~~~~~a::~~a~~ ~~~~~~:~'i:~~~~~~~ ~~;~~~~~
Extension Service, University of Alaska Fairbanks, Fairbanks, Alaska.
-------
Source Evaluation Report (SER) Areas
LF05 - Old Army Landfill
LF07 - Test Landfill
FT08 - Rre Training Area (Past)
S512 - JP-4 Spill, Building 2351
5T15 - Multiproduct Fuel Line
ST16 - MOGAS (Motor Gasoline)
Fuel Line Spill
ST17 - Canol Pipeline Spill
SD21 - Road Oiling - Quarry Road
SD22 - Road Oiling - Industrial Road
SD23 - Road Oiling - Manchu Road
SD24 - Road Oiling - Gravel Haul Road
DP28 - Ry Ash Disposal Site
DP29 - Drum Burial Site
SS30 - PCB Storage Facility
SS31 - PCB Storage Facility
DP40 - Power Plant Sludge Pit
SS41 -Auto Hobby Shop (Past)
SS42 - Miscellaneous Storage
and Disposal Area
$S47 - Commissary Parking Lot
Fuel Spill
WP60 - New Auto Hobby Shop
5562 - Garrison Slough
OU2 Source Areas
ST10 - Bulk Fuel Storage
STll - FiUl Saturated Area
8T13,- Diesel Fuel Spill' ,
8814 - Railroad JP-4 Fuel Spill Area
8T18 - Old Boiler Fuel Spill
ST19 - JP-4 Fuel Line Spill
DP26 - Fuel 7hnk Sludge Burial
. -,
Eielson Air Force Base Location
!
1
Eielson AFB
Boundary
Richardson Hwy
o 5
. I I
Scale in Miles
10
I
t
1
5D23
59310039.1
-------
(»p.f(lN,Jlf,.
"I
~
~
o 500
r\J'\J'\?"'-
\000
\500
.
FIGURE 2 Operable Unit 2 Source Areas
OU2 Record 0 f Decision. Eielson Ajr Force Bose
SCALE \" . 1000'
-------
~
~.
S
.14
NAa.tl;oOIJ23&.DCN
I
t
\
i
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ASBESTC
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Sol ~ Location
Montortlg wen Location
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""-~~
FIGURE 3 .
ST10 and SSW Locatlpn Map
~
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SCAlE r .~ .
~
-------
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-------
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FIGURE 60P26 Location Map
ST13 and
. Elelson I>i Force Bue
. d Of Decision,
OU-2 . Recor .
-------
~
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FIGURE 7
ST19 LocatIOn Map
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OU-2 Record of Decision
Eielson Air FOfC6 Base
Eielson Air Force Base
Operable Unit 2 and Other Areas
Record of Decision
Responsiveness Summary
A.
Overview
The joint cleanup decision preferred by the U.S. Air Force, Alaska Deparnnent of
, Environmental Conservation (ADEC); and U.S. Environmental Protection Agency (EPA) ,
was presented to the public in a Proposed Plan (U.S. Air Force 1993i) and discussed in a
public meeting on November 17, 1993., This plan proposed that three of the Operable Unit
2 (OU2) sites (ST!!, ST18, and ST19) and all of the source evaluation report (SER) sites
discussed would require no funher remedial action. All were found to not pose an .
unacceptable risk to human health and the environment Remedial action was proposed for
the remaining four.OU2 sites (STlO, 5514, STI3, and DP26). The preferred cleanup
method, Alternative 4 of the OU2 Feasibility Study (FS) (U.S. Air Force 1993d), would
use a combination of bioventing, soil vapor extraction, air sparging and groundwater
treatment (at two sites for lead) employed in a phased approach. The guiding principle for
this alternative was to peIfonn in situ treatment of the fuel-contaminated soil and a floating
fuel layer in ,order to halt continued groundwater contamination.
Public COnlments in response to the Proposed Plan and public meeting ranged from solid
support of the plan as the best compromise among cleanup options to mild opposition
against several of the no further action (NF A) proposals. A few residents wanted more
. excavation, but none wanted to delay the process. Treating the source of continuing
contamination (fuel-saturated soil) was supported as a good way to proceed at OU2, and
some suggested the same methods should be applied at some of the fuel-contaminated SER
source areas as well, even though the risk was within the acceptable levels. '
B.
Background on Community Involvement
Pursuant to the signing of the Fetkral Facilities Agreement (FFA) (EP A et ale 1991) with
the State of Alaska and the EPA, the U.S. Air Force began its Superfund cleanup program.
As part of this program, in accordance with Comprehensive Environmental Response,
Compensation, and liability Act (CERCLA) Sections 113(k)(2)(B)(i-v) and 117, an
extensive community relations program was initiated to involve the community in the
decision making process.
The primary means for public involvement was through a public notice period and a public
meeting. The Proposed Plan for OU2 was advertised twice in two local papers. The
public comment period and public meeting were advertised on November 12 in the
Goldpanner base paper. A 9-inch display ad that highlighted the cleanup efforts was placed
in the North Pole Independent on November 5 and 12, and in the Fairbanks Daily News
Miner on November 5, 15, and 16. In addition, more than 3,500 copies were added as an
insert in the base newspaper and delivered to every home in the Eielson Air Force Base
(AFB) housing area. A news release announcing the Proposed Plan and public meeting
was sent to all local news media (radio, television, newspaperS) and the story ran on the
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OU-2 Reccrd of Decision
Eielson Air Force Base
front page of the base newspaper. The meeting was advertised on the base access cable
channel and in the base infonnation bulletin as well as at least one local area radio station.
The base First Sergeants Group (the senior enlisted leadership for each unit on base) was
briefed on the plan and public meeting to encourage their people to attend. Copies of the
plan were delivered to various infonnation repositories, plus the North Pole City Hall.
As part of the U.S. Air Force Installation Restoration Program (IRP), a Technical Review
Committee (IRC) was established in 1992 including three representatives from the
community (selected by local officials and the Chancellor of the University of Alaska,
Fairbanks), industry representatives, and environmental agency representatives, and in
November 1993, a local environmental interest group was invited to participate. Many of
the TRC participants are members of the professional public. The Proposed Plan was
presented to the mc on November 16, 1993. At this meeting; representatives from the
U.S. Air Force, ADEC, and'EPA responded to questions from audience representing the
University of Alaska, the city of North Pole, and various State and federal agencies. '
. .
C. Summary of Comments Received During the Public
Comment Period And Responses .
The public comment period on the OU2 Proposed Plan was held from November 8 until
December 7, 1993. It was extended until Decemrer 20, 1993, because of a typographical
error that required advertising a correction to the plan. Comments received during that
period are summarized below. Part I addresses nontechnical concerns, while Part II
responds to technical and ,legal qu~ons. Each part is grouped by similar topics.
PART I . Summary and Response to Local Community Concerns
Topic: Small Contractors Liability Bonding for Long- Tenn' Cleanups
Public Comment # 1: One person wanted to know if the U .5. Air Force could make a
special provision for small or disadvantaged businesses Who wish to work on cleanups that
could involve a 5- to lO-year effort. Because of the large bond often required in cleanup'
work, and the considerable period of time this money would be unavailable, many smaller
businesses cannot afford this burden and are unable to bid on work for which they are
qualified.
Response: Contracting' issues are policy decisions set by the Department of Defense.
Their policy is to award work only to companies that can insure they can complete a job
satisfactorily by putting up a bond. This bond is required to satisfy the public that
taxpayers will have recourse in.the event of unsatisfactory performance by a contractor. .
Eielson AFB does not have the authority to alter this requirement. However, most of the
cleanup contracts are awarded to large companies who often subcontract to qualified local
businesses. Negotiations between these private companies would not be subject to U.S.
Air Force bonding requirements.
PART n Response to Specific Technical and Legal Questions .
Topic: Groundwater Characterization
Public Comment #2: One person wanted to know the source for drinking water at
Eielson AFB: where does the groundwater flow, and what studies have been done on
groundwater flow rates and directions?
Response: The drinking water for Eielson AFB is supplied by three groundwater wells.
The groundwater is found in spaces in the underground sands and gravels. This water-
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OU-2 Record o( Decision
Eielson Air Force Base
. bearing rock fonnation is 200 to 300 feet thick, and the drinking water is removed from
depths of around 100 feet below the surface. Th~ top of the groundwater is typically 8 to
10 feet below the surface. ..
The direction of groundwater flow at Eielson AFB is generally to the north-northwest.
Locally, it is influenced by Garrison Slough, Hardfill Lake, and pumpage of base supply
wells. The direction of groundwater flow appears to be fairly constant year-round. .
Detennination of groundwater flow rate and direction is an important aspect in the
investigation of possible environmental hazards at Eielson AFB. Portions of each of the
following studies present data on groundwater flow and discuss the results. In addition,
some location-specific hydrological infonnation will be collected during the design phaSe of
the remediation projects. .
Battelle. 1992. "Raw Data for Calculations of Dartian Flow Velocities at the
Eielson Air Face Base." Supplied by Mr~ T. Gilmore of Battelle, Pacific Northwest
Laboratories, Richland, Washington.
.
Battelle. 1992. Remedial InvestigationIFeasibility Study - Operable Units 3.4.
and 5 Management Plan. Eielson Air Force Base. Alaska. Battelle, Environmental
Management Operations, Richland. Washington. (Final).
Battelle. 1992. Remedial InvestigationIFeasibility Study - Operable Unit 2
Baseline Risk AsSeSsment Report. Eielson Air Force Bise. Alaska. Battelle,
Environmental Management Operations, Richland, Washington. (Draft).
lll.A. 1989. Installation Restoration Program Remedial Investigation/Feasibility .
Study. Stage 3. Eielson Air Force Base. Draft Remedial InvestigationiF~bilitY
Study. Volume IT (July 1988 to April 1989). Harding Lawson Associates,
Anchorage, Alaska.
In.A 1990. Installation Restoration Program Remedial Investigation/Feasibility
Study. Stage 4. Draft Remedial InvestigattonIFeasibility Study. Volum~Ithrou~h
V. Harding Lawson Associates, Anchorage, Alaska.
~~. ~~:~4~b~~e~~~~~:;~C:~~: ~~~~~~=~ility
through XVIll. Harding Lawson Associates. Anchorage, Alaska.
SAiC. 1989. U.S. Air Force Installation Restoration Program Remedial
InvestigationIFeasibility Study of the Fuel Saturated Area at Eielson Air Force
Base. Alaska: Draft Remedial Investigation Report. Volumes I. IT. and m.
Science Applications International Corporation (Draft).
U.S. Air Force. 1993. Eielson Air Force Base OU-2 Remf".dial
Investigation/Feasibility Study: Remedial InveStigation Report. Battelle,
Environmental Management Operations, RicbJand, Washington (Final).
U.S. Air Force. 1993. Eielson Air Force Base OU-2 Remedial
InvestigationIFea.c;ibility Study: Remedial Inve.c;tigation Appendixes. Battelle,
Environmental Management Operations, RicbJand, Washington (Final).
U.S. Air Force. 1993. Background Groundwater Ouality. Eielson Air Force
Base. Alaska. Battelle, Enviromriental Management Operations, Richland.
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OU-2 Record of Decision
Eielson Air Force Base
Washington (Final).,
U.S. Air Force. 1993. Site Groundwater Management Plan. Eielson Air Force
Base. Alaska. Battelle, Environmental Management Operations, Richland,
Washingtpn (Draft).
All of these documents are available to the public at the following locations:
Elmer E. Rasmusen Library
Arctic and Polar Regions ArChives Section
University of Alaska '
Fairbanks, AI( 99775
(907) 474-6594
Environmental Management Office
Administrative Records
2258 Central Ave, Suite 1
Eielson' AFB' AI( 99702-2225
(907) 377-5209
Comment #3: Another person stated that groundwater is generally known to flow in a
northwesterly direction; however, seasonal and local variation in groundwater flow may
occur. Cold, dense groundwater and the'interaction of wanner surface waters also appears
to impart a vertical groundwater flow component that can affect the horizontal and vertical
distributi6n of contarilinants. Migration of contaminantS. especially dense nonaqueous
phase liquids (DNAPLs) ~d benzene, can be affected by localized groundwater flow and
show variation in concentrations at various depth zones. Because benzene from fuel'
releases has been shown to migrate great distances, appropriate groundwater analyses
should be perfonned at all contaminated sites at various depth intervals and distances from
the source to provide a complete understanding of contaminant migration. 'Eielson AFB
should demonstrate its comprehensive understanding of the groundwater regimen before
any base-wide recommendation on contaminated sites can be proposed that is protective of
human health and the environment, '
Response: Series of nested wells, wells completed at different depths in the aquifer,
were installed at three of the OU2 sites: ST10, ST18, and DP26. Pressure transducers
were installed,in these wells to detennine the vertical gradient at these sites. Any vertical
gradient, if present, was less than the error of the ~ducers and the E-tape used to
calibrate the transducers- most likely 0.01 feet Much more detail on the measurement of
the vertical gradient at Eielson AFB is provided in the following reference:
U.S. AirForce. 1993. Automatic Water Level Measurements. Eielson AFB.
Alaska. September 1991- August 1992. Battelle. Environmental Management
Operations, Richland, Washington.
The data suggest that groundwater contamination (e.g., benzene) at OU2 is concentrated in
the upper part of the unconfined aquifer. This conclusion is consistent with the very low
vertical gradient and the presence of contaminants that have densities less than water.
No DNAPLs were recognized at the OU2 sites; none were expected because the sources of
contamination at these sites are leaks and spills of fuels.
The concentrations of organic contaminants (including benzene) were measured in all of the
groundwater monitoring wells at the OU2 sites, including those completed at intennediate
depths (30 to 50 feet below the ground surface) and at greater depths (58 to 68 feet at
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Eielson Air Force Base
DP26, 96 feet at STlO). These intermediate wells were completed where the shallow
groundwater was contaminated with B1EX. No groundwater contamination was detected
in the nested wells at STI8. Benzene was detected in one of the intennediate wells at STlO
at a level below its maximum contamination limit (MCL); benzene was detected in the
intermediate well at DP26 at a level greater than its MCL. No other contaminants were
detected in the intermediate wells. No contaminants were detected in the two deep wells.
A summary of the data will be provided to the commenter. "
Topic: SER Sites
Comment #4: One person had a number of comments on the number of samples
collected at DP40 (power Plant Sludge Pit). This person suggested that additional samples
should be taken at DP40 before the site is placed in the no further action category.
Rationalizing reasons to close it is not good enough. A follow-up telephone call indicated
that the concern is with leaching metals out of the boiler walls during acid removal of scale.
Response: Recent actions have occurred at this site. Sludge dredged from the pond is
currently being tested and"will be disposed of in accordance wjth the laboratory results and
State and federal regulations. Pennitted discharges to the pond may ocCur in the future.
Accordingly, this site will be closed as a Comprehensive Environ.TTU!ntal Response,
Compensation, and Liability Act (CERCLA) site and evaluated under Resource
Conservation and Recovery Act (RCRA) for appropriate action. For additional information
on the status of this site, please call the Environmental Compliance Office, Eielson AFB, at
(907) ~77 -1697.
Comment #5: The plan references petroleum, oil, and lubricant (POL) spills from
various sites (SS12~ ST15, ST16) totaling 20,000 gallons. What is not known is the
potential for umeported spills or releases from these facilities of lesser quantities. No or
little sampling was performed to establish the presence or absence of contamination present
in the environment. Contaminated soils were encountered at the Commissary parking lot
(SS47) from an apparently unknown source. Provide justification for no sampling and
analysis from known release sites when fuel contamination was encountered from an
unknown source. It appears that a complete understanding of contamination at these sites
is not fully understood. The source of the unknown petroleum and lead contamination at
the Commissary parking lot warrants further evaluation.
Response: "The potential for unreported historical releases does exist; however, a
review of past activities has been conducted by Consultants. as part of the base IRP.
Sampling under the site-wide " groundwater monitoring program has not indicated the
presence of unreported spills. A fmal site-wide monitoring plan is being developed that
will also serve to identify additional source areas if they do exist.
In addition, we are continuing to seek validation of the review results through public input
Specifically, we sent out over 3,500 copies of the Proposed Plan to members of the base
and SUITOunding community for public comment and to seek any additional information
about conditions at the site. To date, no additional information of other reported spills has
been received.
Soil or groundwater samples were not collected at SS12; however, samples were collected
at ST15 and ST16 and summarized in the Phase I SER report (U.S. Air Force 1993a).
Confirmatory sampling is planned for ST16.
The Proposed Plan states that lead was detected in groundwater in two wells on the
southern portion of the Commissary parking lot Since that time, both wells were
resampled and found to contain only background (natural) concentrations of lead.
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Eielson Air Force Base
Comment #6: It appears from the description in the plan that sampling at Building 6214
(STI6) was not conducted because of the apparent absence of spilled solvents, although
paint spills were apparently noted. What is the basis for not sampling soil and groundwater
even though paint stains are noted?
Response: There were several reasons for not sampling in the vicinity of Building 6214.
First, during a site inspection, U.S. Air Force and ADEC personnel could detect no major
spills or leaks as would be indicated by staining of soils where the drums were stored.
Small deposits of tar or asphalt and several small paint spills were found. These materials
are typically found around any area where asphalt parking lots and roads have been
constructed or buildings are painted. They are only incidental debris and do not represent
or indicate that a significant contaminant release has occuned. Second, Well 16':2 is
downgradient of the site. Water samples from this well do not contain solvents or any
other constituents above MCLs. Therefore, the decision was made not to sample this area.
Additional sampling is planned for this site, however. The Phase I SER (y.S. Air ~orce
1993a) S\3.tes that "Although ST16 is recommended for no further action, supplemental soil
sampling will be performed in the vicinity of Building 6214 during 1994 to confmn that no
significant contamination remains. Groundwater beneath the site will continue to be
monitored as part of a sitewide groundwater monitoring program."
Comment #7: The plan does not adequately summarize the background information for
the Phase I Source Evaluation to allow for comment on the appropriateness of a NFA
recommendation. Although the baseline data are available, it is not possible to provide a
reasonable response t9 the appropriateness of a"NFA Addition~ site evaluations should be
conducted under State guidance. In a follow-up telephone call, the commenter stated that it
would be,difficult to find the time to review the reports and determine if the data actually
support the NF A conclusions. The commenter was concerned about the overall tone of the
plan, which suggested that the U.S. Air Force had investigated the sites with a minimum of
sampling and that the public should trust that the right decisions had been made. The
commenter was also concerned whether the U.S. Air Force was being held to the same
cleanup standards required by the State for small operators.
Response: We appreciate this comment and will keep it in mind for future Proposed
Plans. We recognize that our justification for NFA on many of the sites became quite brief
in our effort to keep the Pr~posed Plan as concise as possible. In fact, additional sampling
is planned for some of the NF A sites, which was' not made clear in the Proposed Plail but
is mentioned in this Responsiveness Summary. Also, the Phase I SER states that "The
groundwater beneath Eielson AFB will contiriue to be monitored as part of a sitewide
groundwater monitoring program~ If it is determined that there are contaminant releases to
the groundwater originating from any areas recommended for no further action, the.
potential source of contamination will be re-evaluated. This re-evaluation may include
additional sampling and/or source characterization."
ADEC and EP A have been involved in'the review and evaluation of the data and decisions
regarding the NF A source areas. These decisions are based, ~ most cases, on field
investigations involving sampling of soils, groundwater, and surface water. Some
management decisions were made, based on gene~ assumptions, in which ADEC and
EP A participated. Ten other SER source areas were reviewed in the same process and
found to require additional sampling before a decision could be made as to their
disposition. These data, site evaluations, and recommendations are presented in the SER
Phase 1 report that ADEC and EPA reviewed and approved. The State has been involved
in this process from the start as specified in the Federal Facility Agreement that dictates
how the CERCLA process is to be organized at Eielson AFB.
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Eielson Air Force. Base
Comment #8: Explain how waste petroleum products an9 waste oils used to control
dust on unpaved road surfaces will evaporate during application and be readily dispersed
by the wind. I do not dispute that there should be no impact; however, the reaSon given is
not valid. .
Response: The commenter is accurate in his implication that road oiling would not be
effective if the applied material evaporated. The statement in the proposed plan was not
intended (0 convey this message but to identify several of the common ways in which
materials applied to a gravel road can be transponed. Some of the volatile components in
the road oil mixture will evaporate during application and others will evaporate from the
roadbed over time. Nonvolatile components will adhere to the fme-grained road particles
and prevent them from being resuspended in the air as dust Over time and with use of the
road, the aggregates of fme particles are broken up and get resuspended in the air as dust
and are dispersed by wind to sUlTounding land.
Comment #9: H a significant volume of fuel (20,000 gallons) was released offbase from
the Canol pipeline, which is used by the U.S. Air Force, should not the U.S. Air Force
evaluate the potential for contaminants in the area of this spill? .
Response: After some research, it appears the original document (1982) identified this
spill erroneously and assigned the spill to the Canol pipeline~ The spill should have been
assigned to the Haines pipeline, which was in operation during 1957. A spill associated
with this pipeline does not fall within the scope of the Eielson AFB Federal F ocility
Agreement and, therefore, is not being addressed under this Proposed Plan.
Topic:
Risk-Based Cleanup Levels
Comment #10: One person wanted. to know if the risk-based cleanup levels used to
guide the cleanup effort, and to which ADEC agreed, were a special concession to the
federal agencies, or if this decision-making process was available for private'sites as well
Response: Eielson AFB signed the Federal Facility Agreem£nt witb the ADEC and EP A
to conduct cleanup activities under the provisions of the CERCLA as amended by the
Superfund Amendments and Reauthorization Act (SARA). These acts include the
provision for risk-based cleanup alternatives as appropriate. The state of Alaska
environmental regulations provide for alternate cleanup standards where appropriate. This
provision is applicable to any site in Alaska, government or private, where the State deems
it appropriate under their regulations.
Comment #11: Groundwater is contained within a single unconfmed aquifer at a
shallow depth under Eielson AFB. This aquifer has been subjected to contaminants of
various source areas resulting in concentrations of contaminants that exceed the federal and.
State MCLs. In the "Summary of OU2 Source Area Risks," the Plan indicates that ..
groundwater is not used. Is not the source of drinking water at Eielson AFB groundwater
from this aquifer? The level of contamination in ST19, ST13, and DP26 exceed MCLs;
however, no cleanup of these areas is planned. Yet, the stated cleanup objectives for
STIO, SS14, ST13, and DP26 are to reduce groundwater contamination levels below
established MCLs, and clean up the soil such that it no longer acts as a contaminant source.
Why is this objective not carried throughout Eielson AFB?
Response: The OU2 Baseline Risk Assessment (ELRA) calculated human-health risk for
three different land-use scenarios at each site. The current industrial land-use exposure
scenario assumed that the current water supply system was used. The future industrial and
future residential land-use scenarios both assumed that water is provided by an untreated
groundwater. well within the site. Thus, the local groundwater contamination was input
into two of the three risk calculations. The groundwater at ST19 and ST13 and DP26 both
exceed MCLs; however, a cleanup of ST13 and DP26 is planned.
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Eielson Air Force Base
A cleanup has not been planned for STl9 because soil and groundwater sampling results
. and the fate and transport modeling both indicate that the contamination at ST19 is restricted
to a liniited area (approximately 2 acres) directly adjacent to the spill area and that the
weathered petroleum contamination in subsurface soils is not expected to act as a significant
continuing source of groundwater contamination. Groundwater concentrations in wells
located downgradient within 1,000 feet of the spill area do not exceed'MCLs. In ~ddition,
ST 19 is located in a remote area of the base that is not likely to be used for residential
purposes in the foreseeable future. Given the low level of residual contamination present
and the limited area impacted, no remedial action will be taken at STI9. Institutional .
controls (e.g., command directives and protective covenants) will be established to prevent
the use of groundwater at ST19 and the groundwater will continue to be monitored to
verify the results of the fate and transport modeling and to ensure protectiveness of human
health and the environment
Comment #12: The underlying theme presented in the plan is that" ...no significant
contamination... II has been determined that warrants further investigation or remediation.
No significant contamination implies that contamination is measurable and present at
concentrations possibly exceeding State guidelines for soil or State and federal MCLs for
water. I understand that the determination of no risk to human health or the environment is
based on a health risk assessment and that a detailed health risk analysis was conducted for
each of the sites in question to anive at this conclusion. Does this health risk include the
understanding of the groundwater regimen?
Response: The OU2 BLRA was performed after the drafting of the OU2 Remedial
Investigation (RI). The RI includes a detailed discussion of the groundwater and this
information was included in the BLRA. To be conservative, the BLRA assumed that the
source of groundwater in future land-use scenarios was completed where groundwater was .
most contaminated. No adjustments were made for future dispersion or degradation of
groundwater contaminants. In addition, contaminant concentrations were also compared to
MCLs to determine the need for remedial action. '
Comment #13: Has the risk assessment included the potential cumulative and synergistic
health effects from all these known and potential source areas? How valid of an argument
can be made that there are no health risks when known releases of refined petroleum
products have occurred on the order of 5,000 gallons but testing has not been performed?
In a fOllow.up telephone call, the commenter indicated that the commenter's concern was
'that three or four 5,OOO-gallon spills had been reported with no field sampling completed.
What is the potential for unreported releases from these facilities? .
Response: The BLRA for the seven OU2 source areas used a conservative approach
when addressing the cumulative effect of contaminants on human health. It was assumed
that the risk from exposure was cumulative, no matter what the contaminant, even. if.those
present affected different organs or caused different types of cancer.
An abbreviated risk assessment was used for the SER source areas because of the lower
probability that these sites would present a significant risk. Detected concentrations were
compared to regulatory criteria such as MCLs, ambient water quality criteria, Alaska
petroleum cleanup standards for soils, etc. These screening criteria were used in
conjunction with other decision criteria to detennine the proper course of action for a
particular source area.
~ suggested in comment # 10, samples were collected at source areas ST15 and STI6.
The only 5,OOO-gallon spill (SS 12) not sampled occurred inside a building. A majori:ty of
the spill was contained in the building with approximately 50 gallons estimated as
unrecovered. There was no evidence to suggest SS12 ev~r contained a significant source
of contaminants. Therefore, it was concluded that any contaminants present would have
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OU-2 Record of Decision
£ielson Air Force Base
likely volatilized or infiltrated through subsurface soils togroundwarer where they would
have been diluted and dispersed .
The reader is referred to comment # 6 for additional response to this concern.
Topic:
Remedial Alternatives Selection
.
Public Comment #14: A local contractor questioned the Soil Venting/Air
SparginglPassive Skimming Alternative (Alternative 4), and recommended the Soil
Excavation/Groundwater Treatment Alternative (Alternative 5).
Response: In many areas at Eielson AFB, excavation is not iniplementable because of
base infrastructure. Excavation could collapse building foundations and rupture piping and
fuel tanks. Also, because much of the contamination resulted from underground leaks,
much of the excavated soil would be clean, but it would have to be removed unnecessarily
to access the contaminated subsurface soils. close to the water table. However,
bioremediation and soil venting.can remediate soil contamination in those areas that cannot
be excavated (e.g., beneath active tanks and piping). As proposed, a much larger volume
of contaminated soils would be remediated with the proposed soil venting and air sparging
systems than could be treated by excavation.
Comment #15: The Proposed Plan indicates that more than 200 years will be required to
allow natural degradation of contaminants, yet cleanup can be accomplished in 5 to 10
years, or worst case, 30 years. Justify long-term groundwater monitoring (200 years?) for
natural degradation of contaminants and the potential for groundwater flow affecting
groundwater uses, compared to implementing corrective action.
I agree that source reduction/elimination, free product recovery, and soil vapor
extraction/groundwater air sparging is, at the present time, the most appropriate treatment
technology suited to cleanup at Eielson AFB. This technology should be considered for its
appropriateness at other known sites where free prodQct is present and/or where soil
contamination will be a continuous source of contaminants to the groundwater.
In a follow-up telephone call, the commenter agreed with the proactive approach to
remediation; however, the commenter had no way of evaluating the cost effectiveness of
the No Action alternative considering the costs of monitoring for 200 years and the impact
on groundwater uses. .
Response: The no action alternative is required by regulation to be evaluated as a baseline
for comparison against other alternatives. However, present worth estimates beyond 30
years become insignificant because of the associated uncertainties and technology .
development which is very difficult to predict that far out in time. For these reasons, the
costs associated with the no action alternative were not estimated.
Topic: Duration of Public Comment Period
,.
Comment #16: The plan was received less than 1 week before the public meeting, which
is not enough time for an adequate review. The Proposed Plan should be available at least
3 weeks before the public meeting.
Response: Your concern is well founded and will be given consideration for future
public rn~tings. The Proposed Plan for OU2 was provided to the Information
Repositories by November 4 and the mailroom by November 5. Because of a long military
weekend that delayed the mailing and a holiday on November 11, many people did not
receive the Proposed Plan until November 12. The date of the public meeting (November
17 ) was also constrained by the availability of the meeting room and the Thanksgiving
holiday on November 25. We will attempt to avoid these problems in the future while
.
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Eielson Ai, Force Base
meeting the scheduling requirements required by regulations. Also, in accordance with the
National Contingency Plan, the U.S. Air Force will, upon timely request, extend the public
comment by a minimum of 30 additional days to allow adequate time for comment from all
interested parties.
D.
Remaining Concerns
Topic: Storage of contaminated snow and ice.
Comment #17: A person suggested that a membrane-lined area be developed for storage
of snow and ice contaminated with petroleum products, an~ze, etc. The snow and ice
could be stored until the spring melt and the contaminants skimmed or treated and packaged
for disposal. .
Response: This problem is cUITently being addressed under the base Hazardous
Materials Program. A building is planned for decontamination of equipment Although the
building may not be available for 3 or 4 years, funding is being actively pursued. The
building will also have the capability of receiving contaminated snow and ice. Oil-water
separation and carbon adsorption equipment will be available for treatment of the melted
snow and ice. Some capability for dealing with contaminated snow and ice currently exists
at the snow barn.
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