PB98-963154
EPA 541-R98-185
March 1999
EPA Superfund
Record of Decision Amendment:
Eielson Air Force Bdse
Fairbanks North Star Borough, AK
9/29/1998
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Eielson Air Force Base
Operable Unit Two and Other Areas
Declaration of the Amended Record of Decision
Site Name and Location
Operable Unit 2
Eielson Air Force Base, Alaska
Statement and Basis of Purpose
This decision document presents the amended remedial action for Operable Unit 2 (OU2) at
Eielson Air Force Base (AFB), Alaska, developed in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA), the May 1991 Federal
Facilities 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.
This decision is based on the Administrative Record for OU2, updated in July 1998, to include
new information generated since the original Record of Decision was signed on 27 September
1994. This amendment applies to OU2 sites ST13, E-4 Diesel Fuel Spill, and DP26, E-10 Fuel
Tank Sludge Burial Site.
The state of Alaska concurs with the amended remedy.
Assessment of the Sites
Actual or threatened releases of hazardous substances from sites ST13 and DP26 within OU2, if
not addressed by implementing the response action selected in this amended Record of Decision
(ROD), may present an imminent and substantial endangerment to public health, welfare, or the
environment.
Description of the Selected Remedy
ST13 and DP26 were treated jointly in the feasibility study because of their physical proximity
and commingled groundwater contamination. The subsurface soils and groundwater at ST13 and
DP26 are contaminated with petroleum products, including benzene, toluene, ethylbenzene, and
xylene (BTEX). The 1994 ROD included the installation of a bioventing system to address the
source of petroleum contamination to the groundwater. The portion of the original selected
remedy addressing the organic subsurface contamination remains unchanged except for the
substitution of passive removal for active removal.
In addition to hydrocarbon contaminants, the OU2 ROD specified lead as a chemical of concern
for the groundwater at Source Areas ST13 and DP26. Total and dissolved lead concentrations in
the groundwater were found to exceed the action level of 15 micrograms per liter (ug/L)
established under the Safe Drinking Water Act. The 1994 ROD specified pump and treat
technology for remediation of the groundwater lead contamination and also specified that the
technology effectiveness be evaluated prior to implementation. The resultant evaluation and
monitoring results concluded that the lead is largely immobile in the subsurface, the contaminant
plume is stable and is not expanding, and that removal of lead contamination is not technically
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feasible. This ROD Amendment is necessary because this new information has led to a
fundamental change in the recommended remedial action for Source Areas ST13 and DP26.
Institutional controls prohibiting use of groundwater within the contaminated area will remain in
place for as long as the contaminant concentrations in groundwater exceed action levels or
MCLs. Groundwater monitoring will be conducted to confirm contaminant containment and
compliance with final remediation goals.
The major components of the amended selected remedy for ST13 and DP26 include:
• Install a passive skimming system to remove fuel floating atop the groundwater at ST13 and
DP26 where the product is sufficiently mobile to be recoverable. Completed 1995.
• Install a bioventing and soil vapor extraction (SVE) system to remediate soil contamination
that poses a threat to groundwater through leaching. Completed 1995.
• Monitor groundwater at ST13 and DP26 to evaluate contaminant levels and migration until
remediation levels are achieved.
• Implement and enforce institutional controls to prevent exposure to contaminated
groundwater. In the event of base closure, contaminated sites will be further addressed in
accordance with CERCLA Section 120 and State of Alaska requirements.
Statutory Determination
The amended selected remedies are protective of human health and the environment and are cost
effective. The amended selected remedies comply with Federal and State requirements that are
legally applicable or relevant and appropriate to the remedial action with the exception of the
action level for lead established under the Safe Drinking Water Act (40 CFR 141.80). A waiver
of the lead action level is justified because compliance with the requirement is technically
impracticable from an engineering perspective. The remedies utilize permanent solutions and
alternate treatment (or resource recovery) technologies to the maximum 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 ST13 and DP26 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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Signature and Support Agency Acceptance of the Amended Remedy for
Operable Unit 2 and Other Areas, Eielson Air Force Base
Chuck Clarke Date
Regional Administrator
Region 10
U.S. Environmental Protection Agency
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AMENDMENT OUTLINE
OPERABLE UNIT 2 RECORD OF DECISION
EIELSON AIR FORCE BASE
SOURCE AREAS STB AND DP26
Page
1.0 Introduction 1
2.0 Reasons for Issuing the ROD Amendment 1
3.0 Need tor Technical Impracticability Waiver . 2
4.0 National Contingency Plan (NPL) Citation 2
5.0 Summary of Site History and Contamination Problems 2
6.0 Description of Original Alternative 4
7.0 Status of Remedial Action 5
8.0 Description of New Alternative 5
9.0 Relationship Between ARARs and the Original Selected Remedy 7
10.0 Basis for New Alternative . 8
11.0 Summary of the Comparative Analysis of Alternatives 8
11.1 Overall Protection of Human Health and the Environment 9
11.2 Compliance with Applicable or Relevant and Appropriate 9
Requirements (ARARs)
11.3 Long Term Effectiveness and Permanence 9
11.4 Reduction of Toxicity, Mobility, or Volume Through Treatment 9
11.5 Short-Term Effectiveness 9
11.6 Implementability 10
11.7 Cost 10
11.8 State Acceptance 10
11.9 Community Acceptance 10
12.0 Technical Impracticability (TT) of Groundwater Restoration 10
12.1 Specific ARARs 10
12.2 Spatial Extent of TI Waiver 11
12.3 Conceptual Model 11
12.3.1 Site Conditions 11
12.3.2 Fate and Transport Investigation 11
12.3.3 EPA Technical Review 12
12.4 Evaluation of Restoration Potential 13
12.4.1 Source Control Measures 13
12.4.2 Restoration Timeframe 14
12.4.3 Other Applicable Technologies 14
13.0 Affirmation of Statutory Determinations 14
14.0 Public Participation Activities 15
15.0 References 16
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TABLES
Page
2.1 ST13 and DP26 Subsurface Soil Concentrations of TPH, BTEX, and Lead 3
2.2 ST23 and DP26 Groundwater Ccr.centrations of TPH, BTEX, 4
and Total Lead
FIGURES
1 ST13/DP26, Location of Groundwaier Monitoring Wells and Soil Borings. Eielson
Air Force Base, AK.
2 Source Area ST13/DP26. Extent of Dissolved Lead in Groundwater (July 1995) and
Floating Fuel Product (Sept 1992).
3 Conceptual Site Model
4 Conceptual Site Model
1.2 (from EA Engineering) Conceptual model of distribution of NAPL in the smear zone
at Eielson AFB source areas
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AMENDMENT
OPERABLE UNIT 2 RECORD OF DECISION
EIELSON AIR FORCE BASE
SOURCE AREAS STB AND DP26
1.0 Introduction
Site name and location: Operable Unit 2. Source Areas ST13, E-4 Diesel Fuel
Spill, and DP26. E-10 Fuel Tank Sludge Burial Site. Eielson Air Force Base,
Alaska.
Lead agencv: Eielson Air Force Base (AFB), U.S. Air Force.
Support agencies: State of Alaska Department of Environmental Conservation
(ADEC).
Region 10, U.S. Environmental Protection Agency (EPA).
Eielson AFB is located within the Fairbanks North Star Borough approximately 21 miles
southeast of Fairbanks and 10 miles southeast of the city of North Pole Alaska, along the
Richardson Highway. Operable Unit 2 (OU2) consists of seven source areas combined
because of commonality in contamination caused by leaks and spills of fuels. Source
Areas -ST13 and DP26 are two of the seven source areas and have fuel and lead
contamination.
The Record of Decision (ROD) for OU2 was developed in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA),
Section 117, as amended by the Superfund Amendments and Reauthorization Act
(SARA), and the May 1991 Federal Facility Agreement (FFA) entered into by the Air
Force. EPA and ADEC (US Air Force 1994). The ROD was signed on 27 September
1994.
2.0 Reasons for Issuing the ROD Amendment
In addition to the hydrocarbon contaminants, the OU2 ROD specified lead as a chemical
of concern for the groundwater at Source Areas STB and DP26. Total and dissolved
lead concentrations in the groundwater were found to exceed the action level of 15
micrograms per liter (ug/L). The ROD specified pump and treat technology for
remediation of the groundwater lead contamination and also specified that the technology
effectiveness be evaluated prior to implementation. Based on the evaluation, The Air
Force and agencies determined that the lead is largely immobile in the subsurface and that
the lead contamination cannot be readily removed using pump and treat technology (US
Air Force 1996). This ROD Amendment is necessary because this new information has
led to a fundamental change in the recommended remedial action for Source Areas STB
and DP26.
Of: KOD Amendment
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3.0 Need for Technical Impracticability Waiver
Because the groundwater will not be restored within a reasonable time frame, a waiver
based on technical impracticability (TI) is necessary. This ROD Amendment provides
the justification for the TI waiver for the lead Action level.
4.0 National Contingency Plan (NPL) Citation
This ROD amendment is presented in accordance with the National Contingency Plan
(NCP), Section 300.435(c)(2)(ii) and will become a part of the OU2 Administrative
Record File in accordance with the NCP, Sec::on 300.825(a)(2). The Administrative
Record File is available for public review at:
Elmer E. Rasmuson Library (Archives Section)
Alaska and Polar Regions Department
University of Alaska Fairbanks
Fairbanks, Alaska 99775
(907) 474-6594
5.0 Summary of Site History and Contamination Problems
At the time the remedial investigation (RJ) report was prepared, the ST13 area included a
fuel pump house, 11 underground storage tanks (UST's), five fuel outlets, and an area
historically used for filling and storing fuel bladders (US Air Force 1993). The DP26
area included a 420,000 gallon above ground storage tank (tank 300) and ancillary piping
and shallow trenches used for burial of sludge from fuel tank cleaning operations.
Upgrade work at these sites conducted in 1994 included removal and close-out of the 11
UST's, installation of a new tank near tank 3
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Table 2.1 ST13 and DP26 Subsurface Soil Concentrations of TPH, BTEX. and Lead
Detection Limit Detected/ Concentration Ranee Lcration of Max.
Constituent
TPH
Benzene
Toluene
Lead
(rng/kg)
1.9-50
0.005 - 0.65
0.005 - 0.65
1
Analyzed
41/55
6/36
10/36
: 3/3
Detected (me/kg)
6.7-31,400
0.02 - 20
0.02 - 220
14.5-60.4
Concentration
'.3SBC-12.7
'.3SBC-12.7
13SBC-12.7
13SBC-07.5
Contaminants of concern in groundwater are benzene, ethylbenzene, toluene, xylenes,
napthalene. and lead. Table 2.2 is also reproduced from the OU2 ROD and Lsts
concentrations of TPH, BTEX, and total lead for groundwater collected from STB and
DP26 monitoring wells. Figure 1, ST13 and DP26 Location Map, shows the location of
monitoring wells and boreholes having the maximum contaminant concentrations.
Table 2.2 ST13 and DP26 Groundwater Concentrations of TPH, BTEX, and Total
Lead
Constituent
TPH
Benzene
Ethylbenzene
Toluene
Total Lead
Detection Limit
(ug/L)
50
5
5
5
1
Detected/ Concentration Range
Analyzed Detected (ug/L)
3/5 100-101,000
18/22 1J-1,400
13/22 1J-1,100
13/22 2J - 4,200
15/20 1.3B-795
Location of Max.
Concentration
13MW02
26MW08
26MW01
26MW08
26MW08
B - Reported value is less than the Contract Required Quantitation Limit but greater than
the Instrument Detection Limit.
J - Estimate value less than Contract Required Quantitation Limit.
As reported in the RI, ST13 maximum groundwater contaminant concentrations in ug/L
were; benzene - 170, toluene - 720, ethylbenzene - 320, xylene - 2,100, and lead - 41.4.
Maximum soil concentrations of TPH and lead were respectively: surface soil - 814 and
88.3 mg/kg and subsurface soil - 31,400 and 60.4 mg/kg. Floating fuel of 0.01 feet
thickness was found in one well at ST13.
At DP26. maximum groundwater contaminant concentrations in ug/L were: benzene -
1.400, toluene - 3,000, ethylbenzene - 1,100. xylene - 6,300. and lead - 795. The
maximum apparent thickness of floating fuel at DP26 was measured at 1.13 reet.
Floating product thickness appears to have decreased over the years. In 1995. 14 of 20
wells sampled at ST13 and DP26 had no floating product and the maximum Apparent
floating product thickness measured was 0.7 feet (US Air Force 1996).
ROD.Xmemlmenl
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6.0 Description of the Original Selected Remedy
The original selected remedy included a combination of 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.
This remedy also included installation of a product and groundwater extraction well near
Tank 300. The groundwater extracted during the implementation of this alternative
would be treated by precipitation to remove the lead and air stripping to remove the
volatile organic compounds.
This original selected remedy was intended to address groundwater contamination by
source reduction and by extraction and treatment of contaminated groundwater.
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 action levels or MCLs. Groundwater monitoring would be conducted to evaluate
contaminant migration and compliance with final remediation goals.
The original specific selected remedies for ST13 and DP26 were as follows:
• 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 a bioventing and soil vapor extraction (SVE) system to remediate soil
contamination that poses a threat to groundwater through leaching.
• Install groundwater extraction and treatment facilities in areas of highest groundwater
lead concentrations at ST13 and DP26. The physical/chemical treatment of the
groundwater includes precipitation of metals and air stripping of volatile organic
compounds
• Monitor groundwater at ST13 and DP26 to 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 STI3 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.
• 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.
The remediation was to be implemented with a phased approach, where ongoing
monitoring would evaluate the performance of each technology before proceeding to the
next phase of cleanup. This phased approach would allow the U.S. Air Force to use field
Ot'2 ROD Amendnieni
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data collected during cleanup to get the best mix of technologies to meet cleanup
objectives
7.0 Status of OU2 Remedial Action
Because of the need to comply with the terms of the FFA, an accelerated remedial design
(RD) schedule was developed utilizing some of the fast tracking work elements provided
for in EPA guidance (EPA 1990) and the Observational Method (Brown et al 1989). The
accelerated RD schedule addressed hydrocarbon (non-lead) contaminants. Based on
discussions with experts in the field and EPA and ADEC representatives, the RD
incorporated bioventing with injection of air five feet below the watertable and passive
floating fuel recovery (Eielson AFB, 1995a and 1995b). Additional data collected during
RD/RA indicated that the weathered floating product at the OU2 source areas is not
sufficiently mobile for use of active floating product removal. Successful operation of
the new bioventing system began on 15 October 1995.
8. Description of the new selected remedy
The selected remedy for sites ST13 and DP26 has been modified as follows.
• Groundwater extraction and treatment facilities will not be installed to address
groundwater lead concentrations.
• Instead of active skimming, passive .skimming systems will be utilized to remove fuel
floating atop the groundwater where the fuel is sufficiently mobile to be recoverable.
• The lead action level for ground water is waived due to technical impracticability.
The amended remedy will comply with all other Applicable or Relevant and
Appropriate Requirements (ARARs).
• As presented in the original alternative, groundwater monitoring will continue and
institutional controls will remain in place to prevent exposure to contaminated
groundwater. Monitoring for potential lead movement at ST13 and DP26 will be
incorporated into the Eielson AFB Sitewide Monitoring Program.
As part of the institutional controls for contaminated soil and groundwater, the Air Force will
develop a written, installation-wide plan that sets out procedures to assure that
institutional controls for soil and groundwater are developed, maintained, monitored, and
remain effective. The plan will be completed within six months of the signature of the
ROD amendment and will apply to all areas on the base requiring institutional controls
for soil and groundwater as part of the remedy. The plan will be reviewed by EPA and
the State of Alaska and is enforceable jointly or severally by them.
The plan shall specify the following:
1.) Eielson AFB will undertake, at a minimum, the following:
a. identify all areas under restriction or control:
b. identity the objectives that must be met by the restrictions and controls;
OU2 ROD Amendment
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c. identify the current and future land users, including, at a minimum, but
not limited to, lessees, contractors, employees, agents, assigns, invitees, and
licensees. In areas where the installation is aware of routine trespassing, the Air
Force will also consider trespassers.
2.) Eielson AFB will establish an 1C process to develop Standard Operating
Procedures (SOPs), incorporated into the Base General Plan (or equivalent document) to
ensure 1C development, implementation, and enforceability for each area which has an 1C
as a component of the selected remedy.
a. Eielson AFB shall consider, and demonstrate to EPA and the Slate, that the 1C
process will cover all entities and persons necessary, including, but not limited to,
lessees, contractors, employees, agents, licensees, trespassers, and invitees.
b. Eielson AFB shall consider and demonstrate to EPA and the State that the 1C
process will cover all activities, including, but not limited to any and all, routine
and non-routine utility work, soil disturbance, groundwater withdrawals, well
placement, drilling, paving, troop training exercises, recreation uses, building,
renovation work on structures or other activities.
c. Eielson AFB shall specify (e.g., through the SOPs) the particular restrictions,
controls and mechanisms which will be used to achieve the identified objectives.
d. Eielson AFB shall include a data base and master installation map that
identifies all land areas under restriction or control, the objectives to be met by the
restrictions or controls, and the particular restrictions, controls and mechanisms
which will be used to achieve the identified objectives.
e. Eielson AFB shall develop a process to ensure that both EPA and state
approval, as appropriate, are obtained prior to any change in identified land use
designation, restrictions, land users or specific activity for any 1C required.
3.) The plan will specify that all current or future land users, whether government
or private entities, will be legally required to abide by the decision document and the 1C
contained therein, and specify the enforcement mechanism or tool that will legally bind
the land user (e.g. leases, licenses, contracts, command directives, etc.).
4.) Eielson AFB shall identify the "point of contact" person or organization
designated as being responsible for implementing, monitoring, maintaining and enforcing
the 1C process.
5.) Eielson AFB shall identify the source of funding for activities required by the
1C process at the installation.
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6.) Eielson AFB will monitor compliance with all aspects of the 1C process on an
annual basis throughout the period of time necessary to implement and maintain the
applicable 1C, unless another monitoring frequency is agreed to by EPA and the state.
7.) Eielson AFB shall conduct field inspections, at least annually, to assess the
condition of all areas at the installation subject to 1C. These inspections will be used in.
determining the effectiveness and protectiveness of all 1C and designated land uses, and
will be used in ascertaining whether the current land and groundwater uses in the areas
are consistent with the 1C for all remediation objectives outlined in the decision document
governing that area. The results of any field inspections shall be documented in a field
inspection report, which shall be sent to EPA and the state within 60 days of the
completion of the field inspection. The designated official responsible for the facility
operations shall certify the accuracy of the field inspections and the continued compliance
with all 1C requirements. Eielson AFB shall provide notice of any change in the
designated official to EPA and the state.
8.) Eielson AFB shall notify EPA and the state immediately upon discovery of
any unauthorized change in an 1C, in land use designation(s), or in any activity which is
inconsistent with the identified 1C. Eielson AFB will allow EPA and the state upon
notification to work with the installation to determine a plan of action to resolve the
unauthorized change/activity. Where the Air Force believes the unauthorized change
creates an emergency situation, the Air Force can respond to the emergency upon
notification to EPA and the state and need not await EPA or state input to determine a
plan of action. Eielson AFB will develop a "feedback loop" to identify what went wrong
with the 1C process, identify how to correct the process to avoid future problems and
requires the correction to be implemented.
9.) Eielson AFB shall notify EPA and the state at least six (6) months prior to,
when possible, but no later than thirty (30) days prior to, any transfer, sale or lease of any
property interest at the installation and define in the notification the process to be utilized
to ensure 1C remain in place, remain effective and remain enforceable.
10.) The 1C Plan, and in particular, the 1C process developed and implemented
under that plan, shall be reviewed as a part of the CERCLA five year review process.
11.) The removal of 1C, completion of 1C, or no further need for 1C must be a
coordinated decision with EPA and the State. In the event of a disagreement, the parties
will resolve the dispute in accordance with Part XXI. Resolution of Dispute, of the
Eielson Air Force Base Federal Facility Agreement.
9. Relationship Between ARARs and the Original Selected Alternative
The ARARs remain unchanged from the original selected remedy. The ARAR for the
lead action level established under the Safe Drinking Water Act (40 CFR 141.80) is
waived due to technical impracticability.
OL'2 ROD Amendment
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10. Basis for the new selected remedy
In accordance with the ROD provision that remediation be implemented with a phased
approach, where ongoing monitoring will evaluate the performance of each technology
before proceeding to the next phase of cleanup, the Air Force evaluated the lead
contamination at ST13 and DP26 and the feasibility of utilizing pump and treat
technology for remediation of lead contamination at the sites. A field investigation was
conducted during the 1995 summer season. The resultant Treatability Study Informal
Technical Information Report (ITIR) concludes that active remediation of the aquifer for
lead is not indicated at this time as (US Air Force 1996).
The study determined that the organic lead originally contained in the fuel has degraded
to an immobile, stable inorganic lead that strongly adheres to the soils within the
groundwater and consequently, the groundwater contamination is contained within an
area approximately 500 feet long. Monitoring data collected during the investigations
confirm that the contamination is not expanding. Any remaining source of more mobile
organic lead will be degraded to the immobile inorganic lead through treatment and
removal of the petroleum products. It would be extremely difficult or technically
impracticable to clean up the groundwater lead contamination by pumping the
groundwater because the lead is so strongly adhered to the soils within the groundwater.
Under the federal Superfund law, when groundwater restoration is technically
impracticable, action focuses on: (1) containment to prevent contaminant migration; (2)
source removal to prevent further contamination of the groundwater; and (3) prevention
of exposures. For ST13 and DP26, the Air Force, EPA, and AD EC have determined that
groundwater restoration for this limited area is technically impracticable; and therefore,
the original remedy of groundwater extraction/treatment is proposed to be changed to:
• Continued monitoring to confirm that the contamination is not migrating and is
remaining within the currently established containment area. Regulatory
requirements would be waived for lead in groundwater within this limited
containment area:
• Degradation of the organic lead to immobile inorganic lead through the existing soil
treatment system that treats and removes the petroleum contamination; and
• Implementation of institutional controls to prevent use of the contaminated
groundwater in this area to ensure protection of human health and the environment.
11.0 Summary of the Comparative Analysis of Alternatives
The following is a brief discussion evaluating the original selected remedy and the new
selected remedy based on the nine criteria presented in the National Contingency Plan
(NCR).
11.1 Overall Protection of Human Health and the Environment
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Both of the alternatives satisfy this criteria. Both of the alternatives would use
institutional controls to prevent exposure to contaminated groundwater and would
employ long term monitoring. Both alternatives also employ bioventing (air injection
five feet below the water table) and floating product removal for remediation of POL
contamination. The pump and treat portion of the original selected alternative will not
provide a significantly greater protection of human health and the environment or a
significantly greater degree of cleanup by treating lead contaminated groundwater since
both alternatives will require decades to achieve lead remediation goals.
11.2 Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)
Both alternatives are expected to achieve groundwater maximum contaminant goals for
all contaminants except lead. The action level for lead is waived due to technical
impracticability from an engineering perspective.
11.3 Long-term Effectiveness and Permanence
Both alternatives aggressively treat the subsurface soils for hydrocarbon petroleum
contamination, including the smear zone soils, through air injection (bioventing) five feet
below the water table. This process is expected to increase both the rate of organic lead
degradation and the rate the inorganic lead is immobilized. Under both alternatives, the
inorganic lead is currently or will become fixed on soil particles. The Air Force will
effectively maintain institutional controls for contaminated soil and groundwater in this
area in accordance with the Institutional Control Plan while contaminant levels exceed
regulatory levels.
11.4 Reduction of Toxicity. Mobility, or Volume Through Treatment
Both alternatives result in a reduction in toxicity, mobility, and volume of contamination
by treating petroleum contamination in the soil and in the groundwater. The groundwater
pump and treat system presented in the original alternative may reduce the amount of
organic lead contamination remaining in the soil and the dissolved lead plume in the
groundwater at a somewhat faster rate, however, the time required would not be
significantly reduced and would still be measured in decades.
11.5 Short-Term Effectiveness
Neither of the alternatives pose an unacceptable risk to residents or workers during
implementation. All potential impacts from construction and system operation will be
controlled using standard engineering controls and practices. The new selected remedy
will present relatively less risk since construction and operation of a pump and treat
system will not be required.
The lead contamination in the groundwater is expected to persist for decades.
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11.6 Implementability
The original alternative using pump and treat technology is feasible to construct but is not
anticipated to significantly reduce lead levels in the groundwater. The new alternative is
more readily implementable because it requires no additional action other than
monitoring, institutional controls and operation of the bioventing and free product
recovery systems.
11.7 Cost
The time required to achieve lead groundwater contamination levels below 15 ug/L at the
lead source would be expected to be decades using pump and treat technology. Because
of the uncertainty associated with cost projections of long duration, the following costs
for the pump and treat system are based on a 40-year life cycle.
Original New
Alternative Alternative
Estimated Capital Cost: $1,150,000 $470,000
Operation and Maintenance/year: $235,000 $70,00
Estimated Present Worth Total Cost: $9,860,000 $ 1,190,000
The estimated costs reflect the additional costs associated with the pump and treat system
proposed in the original alternative. Not included are long term monitoring costs which
are assumed to be the same for both alternatives.
11.8 State Acceptance
The state of Alaska Department of Environmental Conservation (ADEC) concurs with
the modified selected remedy proposed in this ROD Amendment.
11.9 Community Acceptance
No public comments were received in response to the Proposed Plan. Community
participation is discussed in Section 14, Public Participation Activities.
12.0 Technical Impracticability (TI) of Groundwater Restoration
12.1 Specific ARARs
The specific ARAR or media cleanup standards for which the TI waiver applies are as
follows:
• MCLs and maximum contaminant level goals (MCLs. non-zero maximum
contaminant limit goals [MCLGs], and action levels) established under the Safe
10
L": ROD Amsndmini
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Drinking Water Act for groundwater that may be used for drinking water supply (40
CFR 141 and ISAAC 80).
The TI waiver will apply only to lead in the groundwater and specifically to the EPA
established action level of 15 ug/L for lead in drinking water.
12.2 Spatial Extent of TI Waiver
The TI waiver will apply to the area having the.following boundaries (see figure 2).
• Flightline Avenue on the west
• Outer Loop Road on the north
• A line running north and south along the east boundary fence of the .HAZMAT
yard
• A line running east and west along the north boundary fence for Tank 300
The vertical extent of the TI waiver will range from the water table to 30 feet below the
average annual water table depth.
12.3 Conceptual Model
12.3.1 Site Conditions
The site lithology is generally homogeneous and is predominantly sand and gravel with
very thin discontinuous layers of silt encountered in less than ten percent of site
lithological samples (U.S. Air Force 1996 page 5-1). The depositional environment
consists of fluvial and glacial fluvial deposits. Most of the sediments were deposited in
the principal stream beds during higher energy deposition. The thickness of the alluvial
fan deposits are in the hundreds of feet.
The water bearing zone is characterized by a low hydraulic gradient and highly
transmissive aquifer materials. The mean hydraulic gradient is 0.002 with the highest
(0.05) occurring during a four week period in May and the lowest (0.0013) occurring over
a seven month period from September to March (U.S. Air Force 1996 page 5.2). A
hydraulic conductivity value of 380 feet/day was estimated from an August 1995
pumping test (U.S. Air Force 1996 page 5.1). The aquifer has a slow vertical rate of
mixing which serves to confine groundwater contaminants near the water table (U.S. Air
Force 1993b. page 4.1).
12.3.2 Fate and Transport Investigation
The investigation indicates that the major source of lead contamination is from the
floating product plume as shown in Figure 2. The lead plume is confined to a small area
north of the above ground storage tanks at DP26 and appears to coincide with the historic
extent of the floating product plume. During the investigation, tetraethyl lead (TEL), the
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organic lead fuel additive, was detected in a floating product sample at a level of 319,000
ug/L and at low levels in the groundwater, i.e., 6 ug/L (page ES-3). The groundwater
TEL plume was coincident to that of inorganic lead. The investigation also established
that the lead contamination is confined to depths between 5 and 30 feet below ground
surface (page 5-3).
A RANDOM WALK model predicted that the lead could migrate 50 feet in 500 years
(page 5-9). The report qualified this prediction, however, stating that, because of the
uncertainty associated with predicting lead transport, conservative input parameters
(Retardation Factor Rf = 166, page 5-6) were used which demonstrate that the plume will
not move appreciably in 100 years and that the concentrations will have diminished
substantially at the core (page 5-23). The report also points out that the lead plume has
not migrated over the time period for which lead in groundwater data are available (1988
through 1995) (page ES-3). Associated lead transport modeling indicated that aquifer
restoration would require approximately 100 years. This prediction is also very uncertain
for the reasons stated above.
12.3.3 EPA Technical Review
In a technical review of the report, EPA indicates that the following report conclusions
are valid (see Appendix E, US Air Force 1996 page ES-1).
• The source of the lead is the leaded fuel leaked from the USTs and the associated fuel
hydrant system as well as unknown buried fuel tank sludge.
• Lead was transported with the fuel product in the vadose zone and on the water table.
• Organic lead in the fuel product has degraded to inorganic lead which is strongly
adsorbed to the vadose zone and aquifer matrix.
• The groundwater lead plume has not migrated over the time period for which lead in
groundwater analytical data are available.
The reviewers, however, did not agree with the use of the RANDOM WALK model
presented in the report. The model significantly overstated the mobility of lead in
groundwater and the model uncertainties are so high that the model results cannot be used
to make risk management and remediation decisions (page 5).
A conceptual model, based on empirical data, is represented in figures 3 and 4. In the
model, advection refers to the transport and dispersion of lead contamination by the
groundwater. As the petroleum hydrocarbons with TEL and inorganic lead are dissolved
in the groundwater. the TEL is degraded to inorganic lead relatively quickly through
physical, chemical and biological processes. The report indicates that TEL has a half life
of 2 to 8 weeks (page 4-10). When the conversion occurs, the inorganic lead has a very
strong tendency to sorb onto organic matter and the soil matrix. At this point the
inorganic lead is nearly immobilized.
Initially, because migration of the lead is retarded, the BTEX plume may expand beyond
the limius ot" the lead contamination plume. After the fuel source is removed and
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biodegradation continues to act on the fuel, the size of the fuel plume will decrease with
time. As the TEL is transformed to inorganic lead, it is fixed in place. The size of the
area contaminated by lead will not decrease and the lead will not move with the
groundwater.
In fact, the BTEX plume at ST13 and DP26 has expanded beyond the extent of the lead
plume by a significant amount and has begun to decrease in size (U.S. Air Force 1996
page 2-7). The air injection system operation which began in October 1995 is intended to
remove the BTEX contaminant source and is expected to accelerate reduction of the
BTEX plume. This activity will also accelerate the organic lead degradation rate and the
resultant sorption of inorganic lead.
12.4 Evaluation of Restoration Potential
12.4.1 Source Control Measures
Replacement of the original tank 300 in 1988 and removal of eleven USTs and upgrading
of the associated fuel hydrant system in 1994 have removed the source of lead
contamination. The USTs were used in the 1950s and 1960s to store leaded aviation
gasoline, and, based on observations made during the 1994 construction effort, the USTs
and fuel hydrant system leaked extensively (U.S. Air Force 1996 page 1-1). No fuels
with lead additives were stored or used at the site after the early 1970s (page 5-3).
Efforts to remove the fuel contaminants include passive recovery of floating product and
operation of a bioventing system in which air is injected five feet below the water table
(U.S. Air Force 1995a, 1995b). Air is injected below the water table to promote
volatilization and remediation of contaminants in the smear zone as well as in the vadose
zone. Operation of the remediation system began in the fall of 1995.
Restoration of the site is constrained by the mobility of the lead. Modeling efforts predict
that a pump and treat system will require greater than 100 years to remove the lead
contamination. The report concludes that lead is largely immobile in the subsurface at
ST13/DP26 and that lead contamination cannot be cleaned up using pump and treat
technology.
No cleanup technology is available that will significantly reduce the time required to
restore the aquifer. Soil excavation is not practical because the majority of the
contamination is within the saturated zone (U.S. Air Force 1994). Because the source
area is adjacent to active taxiways, fuel outlets, fuel storage tanks, buried pipelines.
buildings and other facilities, soil excavation would disrupt base activities.
Regarding floating fuel recovery, recent information indicates that active skimming for
product recovery at Eielson AFB is not practical at sites which involve weathered product
associated with historical fuel spills. Field observation of recovery into wells indicates
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that free product is generally not "mobile" and thus is not recoverable in large quantities
(see OU1 Remedial Design, US Air Force 1995c). EA Figure 1.2 provides a conceptual
model of distribution of free product at Eielson AFB. This concept is supported by other
individuals knowledgable in the field (Christianson 1995b. Memorandum 19 April).
Based on this information, the Air Force. EPA and ADEC have agreed that the main
remediation efforts should include bioventing (or air injection) and only simple, cost
effective free product removal methods (such as passive skimming) should be employed
(Christianson. 1995a. Memorandum 3-March).
12.4.2 Restoration Timeframe
As outlined in Section 12.3, Conceptual Model, the modeling effort predicted that
restoration of the site using pump and treat technology could require 100 years or more
and suggested that this estimate is conservative and the time required could be
significantly longer. The EPA review stated that the model uncertainties are so high that
the model results cannot be used to make remediation decisions. The EPA review also
stated that the lead is relatively immobile and cannot be cleaned up using pump and treat
technology.
12.4.3 Other Applicable Technologies
The ROD evaluated two remedial technologies as having potential for lead remediation at
Source Area ST13/DP26: excavation of known subsurface soil hot spots or groundwater
extraction with physical/chemical treatment. The ROD selected groundwater extraction
with physical/chemical treatment as potentially the most practical approach with the
provision that remediation should be implemented with a phased approach so that each
technology could be evaluated before moving to the next step (U.S. Air Force 1994 page
iii). Excavation was not selected as an alternative because it would be poor in
effectiveness and implementability since it is not possible to excavate large volumes of
contaminated soil near pipelines, tanks, and operating systems, nor in the smear-zone soil
(page 53).
13.0 Affirmation of Statutory Determinations
The amended selected remedies are protective of human health and the environment and
are cost effective. The amended selected remedies comply with Federal and State
requirements that are legally applicable or relevant and appropriate to the remedial action
with the exception of the action level for lead established under the Safe Drinking Water
Act (40 CFR 141.80). A waiver of the lead action level is justified because compliance
with the requirement is technically impractical from an engineering perspective. The
remedies utilize permanent solutions and alternate treatment (or resource recovery)
technologies to the maximum extent practicable and satisfy the statutory preference for
remedies that employ treatment that reduces toxicity. mobility, or volume as a principal
element.
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Because these remedies will result in hazardous substances remaining onsite above
health-based levels, .reviews will be conducted at sites ST13 and DP26 within 5 years
after commencement of remedial action to ensure that the remedy continues to provide
adequate protection of human health and the environment.
14.0 Public Participation Activities
The proposed ROD amendments and TI waiver considered by the U.S. Air Force, ADEC,
and EPA were presented to the public in the Proposed Plan for Operable Unit 2 and
Operable Units 3. 4, 5. The Proposed Plan was released to the public in May 1996 and
discussed in a public meeting on 23 May 1996. The Proposed Plan outlined proposed
changes to the selected remedies for addressing soil and ground water contamination in
the Records of Decision for OU 2 and OUs 3, 4, and 5. The public comment period for
the Proposed Plan was from May 13 to June 12, 1996. There were no formal comments
received during the public meeting or during the public comment period.
The original OU2 Proposed Plan was presented to the Technical Review Committee
(TRC) on November 16, 1993. The TRC was established in 1992 and included three
representatives from the community (selected by local officials and the University of
Alaska Chancellor), industry representatives, and environmental representatives. The
TRC was converted to a Restoration Advisory Board (RAB) in the Spring of 1995. Three
community representatives were selected as RAB co-chairpersons, one each from the
communities of Salcha, Moose Creek, and North Pole, Alaska. The RAB met during the
public comment period on May 23, 1996 to review the Proposed Plan for the amended
remedy.
The public comment period, public meeting, and Proposed Plan for the amendment
changes for OUs 2, 3, 4, and 5 were advertised twice in two local newspapers. The
advertisement appeared in the Fairbanks Daily News-Miner on May 12, 1996 and in the
Goldpanner on May 17. 1996. Proposed Plans were mailed to more than 150 people on
the clean up mailing list on May 13. In addition, members of the RAB and 354
CES/CEVR created a short informational commercial which was aired as a public service
announcement thirteen times prior to the public meeting on local television channels 2,4,
and 11. The Administrative Record is available for public review as identified in Section
1.5.
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15.0 References
Brown, S.M., Lincoln. D.R. & Wallace, A.W. 1989. Application of the Observational
Method to Remediation of Hazardous Waste Sites. CH2M Hill, Bellevue, Washington.
EPA. 1990. Guidance on Expediting Remedial Design and Remedial Action.
EPA/540/G-90/006, U.S. Environmental Protection Agency, Office of Emergency and
Remediation Response. Washington DC 20460.
Christiansen, C. 1995. 554 CES/CEVR, Eielson Air Force Base, Alaska. Memorandum.
3 March.
Christianson, C. 1995. 354 CES/CEVR, Eielson Air Force Base, Alaska. Memorandum.
19 April.
U.S. Air Force. 1993 Eielson Air Force Base OU2 Remedial Investigation/Feasibility
Study: Remedial Investigation Report. Battelle, Environmental Management Operations,
Richland, Washington (Final).
U.S. Air Force. 1994. Eielson Air Force Base Operable Unit 2 and Other Areas Record
of Decision.. Eielson Air Force Base, Alaska.
U.S. Air Force. 1995a. Remedial Action Workplan, Remedial Design Operable Unit 2,
Eielson Air Force Base. AGRA Earth and Environmental, Inc., Fairbanks, Alaska.
U.S. Air Force. 19955. Project Specifications, Remedial Design Operable Unit 2,
Eielson Air Force Base. AGRA Earth and Environmental, Inc., Fairbanks, Alaska.
U.S. Air Force. 1995c. Operable Unit 1 Remedial Design, Eielson Air Force Base
Alaska. EA Engineering. Science, and Technology, Fairbanks, Alaska.
U.S. Air Force. 1996. Eielson Air Force Base Operable Unit 2, Source Areas
ST13/DP26, Treatabliliry Study Informal Technical Information Report. Air Force
Center for Environmental Excellence, Brooks Air Force Base, Texas.
Utah Water Research Center. 1997. Intrinsic Remediation Engineering Evaluation/Cost
Analysis for Site 13/26. Eielson Air Force Base, Alaska. Air Force Center for
Environmental Excellence. Brooks Air Force Base, Texas.
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