EPA Superfund Record of Decision Amendment: Eielson Air Force Base EPA ID: AK1570028646 OU 03 04 05 Fairbanks AK 09/29/1998


                                   EPA/AMD/R10-98/186
                                   1998
EPA Superfund
     Record of Decision Amendment:
     EIELSON AIR FORCE BASE
     EPA ID: AK1570028646
     OU 03, 04, 05
     FAIRBANKS, AK
     09/29/1998

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EPA 541-R98-186


                          Eielson Air Force Base
                        Operable Units 3, 4, and 5

               Declaration of the Amended Record of Decision

Site Name and Location

Operable Units 3, 4, and 5
Eielson Air Force Base, Alaska

Statement and Basis of Purpose

This decision document presents the amended remedial action for Operable Units 3, 4, and 5
(OUs 3, 4, and 5) 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 OU 3, 4, and 5, updated in July 1998, to include new information generated
since the original Record of Decision was signed on 30 September 1995. This amendment
applies to OU3 site DP44  (Battery Shop Leach Field Building),  OU4 sites SS35 (Asphalt
Mixing Area) and ST58  (Old Quartermaster Service Station), and OUS sites LF03/FT09
(Current Inactive Base Landfill/Fire Training Area).

The State of Alaska concurs with the selected remedy.

Assessment of the Sites

Based on new information made available after signing of the Record of Decision  (ROD)
document,  EPA, ADEC and Eielson Air Force Base have selected alternate actions for sites
DP44, SS35, ST58, and LF03/FT09 that are more appropriate for existing site conditions
than those referenced in the original ROD document. Through new information, contaminant
levels at these sites were determined to be at lower levels than interpreted prior to
signing the original ROD document. Proper enforcement of Institutional Controls  (IC's) at
all sites will be effective in controlling and restricting access to contaminated media at
the sites until remediation goals are achieved. Implementation of the amended selected
alternative actions in the ROD amendment are shown, through evaluation against the nine
criteria presented in the National Contingency Plan  (NCP), to be as protective of human
health and the environment as the remediation alternatives originally selected for these
sites.

Description of the Amended Selected Remedy

Site DP44: DP44 is believed to be the location of past jet engine maintenance activities
near an aircraft maintenance facility.  Contaminants of concern are petroleum compounds and
solvents in soil and groundwater.  Additional investigation and pilot testing at the site
indicate that contamination levels have decreased significantly through natural
attenuation and biodegradation in both the soils and groundwater; therefore, the original
remedy of soil vapor extraction is proposed to be changed as follows:

•       Residual soil contamination is not expected to act as a continuing source of
       groundwater contamination.  No further action of soils is proposed.

•       Continued monitoring to confirm that the groundwater contamination is not migrating
       and that contaminant levels are  continuing to decrease.

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• Implementation of institutional controls to prevent use of the contaminated
groundwater in this area.

Site SS35: SS35 was used as an asphalt cement mixing area from the early 1950's to the
late 1960's. Approximately 200 empty asphalt cement drums were reportedly disposed along
the banks of Garrison Slough in this area. The original selected remedy included
installation of a soil cover over the area to prevent direct contact and surface water
runoff into Garrison Slough. Based on re-evaluation of site conditions from new
information gathered after the ROD was signed, additional soil cover is not necessary for
protection of human health or the environment at SS35. The amended selected remedy is:

• No action under the Superfund program: and

• Continued monitoring of surface water, sediments, and aguatic organisms at the site
to confirm that concentrations remain at levels that are protective of human health
and the environment.

Site ST58: ST58 was the site of a service station that was decommissioned in 1988.
Contaminants of concern are lead and petroleum compounds in the soil and groundwater.
For the lead contamination at ST58, subseguent evaluations and modeling have determined
that groundwater restoration for this confined area is technically impracticable. For the
petroleum contamination a 1993 removal of BTEX-contaminated soils from the most
contaminated area of the site removed a majority of the petroleum contaminated soils. The
level of remaining residual soil contamination does not warrant installation of a
bioventing soil treatment system. Additional investigations have indicated that petroleum
contamination is being addressed through natural attenuation and biodegradation in both
the soils and groundwater; and therefore, the original remedy of bioventing is proposed to
be changed as follows:

• Residual soil contamination does not appear to be adversely impacting the
groundwater; therefore, no further action of soils is proposed.

• Continued monitoring to confirm that the groundwater lead or petroleum contamination
are not migrating and are remaining within the currently established containment
area.

• The action level would be waived for lead contamination in aroundwater within this
limited containment area due to technical impracticability from an engineering
perspective.

• Implementation of institutional controls to prevent exposure to contaminated
groundwater in this area to ensure protection of human health and the environment.

Sites LF03/FT09: LF03 occupies approximately 100 acres and was used as the main base
landfill from 1967 to 1987. FT09, which is located on top of the landfill, was used for
fire-training exercises from 1955 to 1989. No fundamental changes are proposed to the
selected remedy; however, clarification of regulatory issues is warranted. The Air Force
had previously indicated that there was documented evidence of disposal of hazardous waste
in the post-1980 disposal area. A subseguent search of Air Force and Fairbanks North Star
Borough records after the signing of the original ROD could not confirm this disposal of
hazardous waste. Given the lack of documentation of hazardous waste disposal RCRA subtitle
C is relevant and appropriate as an ARAR but is not applicable. Groundwater concentrations
adjacent to the landfill are below State and federal regulatory levels, therefore an
impermeable cover to prevent movement of groundwater through the landfill is not
warranted. The amended selected remedy is clarified as follows:

• A cover to address the direct contact threat will be maintained in accordance with
relevant and appropriate reguirements of the Resource Conservation and Recovery Act
Part 264 and the Hybrid - Landfill Closure described in OSWER Directive 9234.2-04FS,
"RCRA ARARS: Focus on Closure Reguirements".

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•      Groundwater at and adjacent to the landfill will continue to be monitored to verify
       that contaminant concentrations remain below acceptable regulatory levels.

•      Institutional controls will be implemented to restrict land use to prevent direct
       exposure to landfill waste

The major components of the amended selected remedies for sites DP44,  SS35,ST58, and
LF03/FT09 include

•      Monitor surface water,  sediments,  and aquatic organisms at Site SS35 to confirm that
       contaminant concentrations remain at levels that are protective of human health and
       the environment.

       Monitor groundwater at sites DP44, ST58,  and LF03/FT09 to evaluate contaminant
       levels and migration until remediation levels are achieved.

•      Application of the Technical Impracticability Waiver to lead groundwater
       contamination at site ST58.

•      Implement and enforce institutional controls to prevent exposure to contaminated
       media at DP44, ST58, and LF03/FT09.

In the event of base closure, any remaining contaminated sites will be addressed in
accordance with CERCIA 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 to the maximum extent practicable. However, because treatment
of the principal threats of the sites were found to be practicable, these remedies do not
satisfy the statutory preference for treatment as a principal element.

Because these remedies will result in hazardous substances remaining onsite above
health-based levels, reviews will be conducted at sites DP44, ST58, and LF03/FT09 each 5
years during the five-year ROD review process to ensure that the remedies continue to
provide adequate protection of human health and the environment.
Signature and Support Agency Acceptance of the Amended Remedy for
Operable Units 3, 4, and 5, Eielson Air Force Base

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                               AMENDMENT OUTLINE
                 OPERABLE UNITS 3,4,5 RECORD OF DECISION
                          EIELSON AIR FORCE BASE
                SOURCE AREAS DP44, SS35, ST58, & LF03/FT09

1.0 INTRODUCTION                                                               4

   1.1 SITE NAME AND LOCATION                                                  4
   1.2 IDENTIFICATION OF LEAD AND SUPPORT AGENCIES                             4
   1.3 CITATION OF CERCLA SECTION 117 AND NCP SECTION  300.435(c)(2)(ii)        4
   1.4 SUMMARY OF THE CIRCUMSTANCES THAT LEAD TO THE NEED FOR A               4
   ROD AMENDMENT
   1.5 STATEMENT THAT THE ROD AMENDMENT WILL BECOME PART OF  THE
   ADMINISTRATIVE RECORD                                                        5
   1.6 ADDRESS OF LOCATION AND HOURS OF AVAILABILITY OF THE
   ADMINISTRATIVE RECORD                                                        5

2.0 SUMMARY OF SITE HISTORY, CONTAMINATION PROBLEMS, AND SELECTED
REMEDY                                                                         5

 2.1 DP44 SITE HISTORY                                                          5
  2.1.1 CONTAMINATION PROBLEMS                                                  5
  2.1.2 THE SELECTED REMEDY FOR DP44 AS ORIGINALLY DESCRIBED IN
         THE OU3,4,5 ROD                                                        7
  2.1.3 AMENDED SELECTED REMEDY                                                  8
 2.2 SS35 SITE HISTORY                                                           9
  2.2.1 CONTAMINATION PROBLEMS                                                   9
  2.2.2 THE SELECTED REMEDY FOR SS35 AS ORIGINALLY DESCRIBED IN
         THE OU3,4,5 ROD                                                        10
  2.2.3 AMENDED SELECTED REMEDY                                                  11
 2.3 ST58 SITE HISTORY                                                          12
  2.3.1 CONTAMINATION PROBLEMS                                                   13
  2.3.2 THE SELECTED REMEDY FOR ST58 AS ORIGINALLY DESCRIBED IN
         THE OU3,4,5 ROD                                                          14
  2.3.3 AMENDED SELECTED REMEDY                                                   14
 2.4 LF03/FT09 SITE HISTORY                                                       16
  2.4.1 CONTAMINATION PROBLEMS                                                    17
  2.4.2 THE SELECTED REMEDY FOR LF03/FT09 AS ORIGINALLY DESCRIBED
         IN THE OU3,4,5 ROD                                                        18
  2.4.3 AMENDED SELECTED REMEDY                                                    19

3.0 SUMMARY OF COMPARATIVE ANALYSIS                                                20

  3.1 OVERALL PROTECTION OF HUMAN HEALTH AND THE
  ENVIRONMENT                                                                      20
  3.1.1 SITE DP44                                                                  20
  3.1.2 SITE SS35                                                                  20
  3.1.3 SITE ST58                                                                  20
  3.1.4 SITE LF03 & FT09                                                            21
3.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS (ARARS)                                                                21
  3.2.1 SITE DP44                                                                   21
  3.2.2 SITE SS35                                                                   21
  3.2.3 SITE ST58                                                                   21
  3.2.4 SITE LF03 & FT09                                                            21
3.3 LONG-TERM EFFECTIVENESS AND PERMANENCE                                          21
  3.3.1 SITE DP44                                                                   21
  3.3.2 SITE SS35                                                                   21
  3.3.3 SITE ST58                                                                   21
  3.3.4 SITE LF03 & FF09                                                            22

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3.4 REDUCTION OF TOXICITY, MOBILITY, OR VOLUME THROUGH TREATMENT                   22
  3.4.1 SITE DP44                                                                   22
  3.4.2 SITE SS35                                                                   22
  3.4.3 SITE ST58                                                                   22
  3.4.4 SITE LF03 & FT09                                                            22
3.5 SHORT-TERM EFFECTIVENESS                                                        22
  3.5.1 SITE DP44                                                                   22
  3.5.2 SITE SS35                                                                   22
  3.5.3 SITE ST58                                                                   23
  3.5.4 SITES LF03 & FT09                                                           23

3.6 IMPLEMENTABILITY                                                                23
  3.6.1 SITE DP44                                                                   23
  3.6.2 SITE SS35                                                                   23
  3.6.3 SITE ST58                                                                   23
  3.6.4 SITES LF03 & FT09                                                           23

3.7 COST                                                                            23
  3.7.1 SITE DP44                                                                   23
  3.7.2 SITE SS35                                                                   23
  3.7.3 SITE ST58                                                                   24
  5.7.4 SITES LF03 & FT09                                                           24
 3.8 STATE ACCEPTANCE                                                               24
 3.9 COMMUNITY ACCEPTANCE                                                           24

4.0 TECHNICAL IMPRACTICABILITY OF GROUNDWATER RESTORATION                           24

  4.1 SPECIFIC ARARS                                                                24
  4.2 SPATIAL EXTENT OF TI WAIVER                                                   24
  4.3 CONCEPTUAL MODEL                                                              25
    4.3.1 SITE CONDITIONS                                                           25
    4.3.2 FATE AND TRANSPORT INVESTIGATION                                          25
    4.3.3 EPA TECHNICAL REVIEW                                                      26
 4.4 EVALUATION OF RESTORATION POTENTIAL                                            27
   4.4.1 SOURCE CONTROL MEASURES                                                    27
   4.4.2 RESTORATION TIMEFRAME                                                      27

5.0 INSTITUTIONAL CONTROLS                                                          27

6.0 AFFIRMATION OF THE STATUTORY DETERMINATIONS                                     30
7.0 RESPONSIVENESS SUMMARY                                                          30

   7.1 BACKGROUND ON COMMUNITY INVOLVEMENT                                          30
   7.2 SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC
        COMMENT PERIOD AND USAF RESPONSES                                           31

8.0 REFERENCES                                                                      31

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1.0 Introduction

1.1 Site Name and Location:

Operable Unit 3,4,5, Source Areas DP44, SS35, ST58, LF03/FT09,
Eielson Air Force Base, Alaska.

1.2 Identification of Lead and Support Agencies

Lead agency: Department of Defense, Eielson AFB, Alaska
              Program Manager:    Michael Raabe
                               354 CES/CEVR
                               2258 Central Ave Ste 100
                               Eielson AFB,  AK 99702-2299
                              (907)  377-1164
Support Agencies: U.S. Environmental Protection-Agency, Region 10
                  Project Manager: Mary Jane Nearman
                                    Office of Environmental Cleanup Unit #4
                                    1200 - 6th Avenue, HW - 124
                                    Seattle, WA 98101
                                    (206)  553-6642
                  Alaska Department of Environmental Conservation
                  Project Manager: Ronan Short
                                    610 University Avenue
                                    Fairbanks,  AK 99709-3643
                                    (907)  451-2156, (907)  451-2183

1.3 Citation of CERCIA Section 117 and NCP Section 300.435(c)(2)(ii) and Date of ROD
signature

The OU 3,4,5 ROD amendment has been prepared in accordance with the procedures specified
in CERCLA section 117 and the National Contingency Plan section 300.435  (c)(2)(ii). The
original ROD was signed on 30 September 1995.

1.4 Summary of the Circumstances That Led to the Need for a ROD Amendment

Based on recent sampling results at site ST58,  a pilot scale soil vapor extraction system
at site DP44, clarification of RCRA Subtitle C with respect to LF03/FT09, and a
re-evaluation of the Baseline Risk Assessment for OU 3,4,5 and Sitewide Biological Risk
Assessment with respect to site SS35,  the selected remedies are being amended from those
presented in the original ROD for OUs 3, 4,  and 5. The new information indicates that
another alternative from those selected in the ROD provides the best balance of the
tradeoffs among the alternatives with respect to the nine evaluation criteria.

1.5 Statement That the ROD Amendment Will Become Part of the Administrative Record File

The OU 3,4,5 ROD amendment shall be added to the administrative record file in accordance
with the NCP section 300.825 (a) (2).

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1.6 Address of Location and Hours of Availability of Administrative Record File

The OU 3,4,5 ROD with the Responsiveness Summary and this ROD amendment will be
available in the Administrative Record at the information repositories listed below.
Information used to support the selection of the amended remedy has been included in the
Administrative Record, which 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

2.0 Summary of Site History, Contamination Problems, and Selected Remedy

2.1 DP44 Site History

Source area DP44 is located near the Large Aircraft Maintenance Hangar (Bldg. 1140) . As
originally defined, DP44 included the wastewater disposal leach field from the battery
shop (Building 1141) and the area around Building 1138 between the runway taxiway and
Flightline Avenue west of the North street intersection (see Figure 2.1 in OU3,4,5 ROD).
DP44 was identified as a source area because, in the past, the battery shop and Building
1138 may have discharged waste into a leach field system within the area. However,
subseguent investigations have not confirmed the existence of this leach field. Most of
the contamination in this source area is located south of the hangar, and is probably
related to past jet-engine maintenance activities in the hangar. Identified contaminants
of concern are fuel-related compounds and solvents in the groundwater and soil.

2.1.1 Contamination Problems

Soil contaminants greater than EPA risk-based screening levels or background
concentrations for DP44 are summarized in Table 2.1. Soil contaminants listed in Table 2.1
are poly aromatic hydrocarbons (PAHs) that were found at maximum concentrations in a
surface soil sample collected during the drilling of Well 44M03. This sample was collected
in a gravel parking lot that contained fragments of asphalt. Because the parking lot is in
close proximity to the runway, it was routinely maintained by spraying oil for dust
suppression. The source of the PAHs could be from exhaust from vehicles parked in the lot,
exhaust from aircraft on the nearby runway, or asphalt residue. These contaminants are
highly sorptive and immobile.

The concentrations of solvent and benzene did not exceed screening levels for direct
exposure. However, subsurface concentrations of solvent and benzene were estimated to be
sufficiently high to leach into the groundwater to yield concentrations that exceed
groundwater screening levels. Therefore, even though solvent and benzene contamination in
soils does not exceed screening levels based on direct exposure to the soil, it may be the
source of groundwater contamination through the leaching pathway.

In August 1994, 13 soil borings were drilled in the vicinity of Well 44M04 to determine
the extent and concentration of chlorinated solvents in soils south of the large aircraft
maintenance hangar. Locations for the borings, were determined using a soil-gas survey.
The soil-gas survey indicated that contaminated soils extended to the west under the
aircraft parking ramp. The borings were completed through the vadose zone to the water
table, located at approximately 3 m (10 ft) below land surface in this vicinity. Samples
were taken at three depth intervals, 0.6 to 1.2 m (2 to 4 ft), 1.2 to 1.8 m, (4 to 6 ft),
and 2.4 to 3 m (8 to 10 ft) below land surface. The samples were analyzed for chlorinated
solvents and BTEX compounds. TCE and total DCE results are illustrated in Figures 6.1
through 6.3 in the OU3,4,5 ROD. Low levels (less than screening levels) of toluene were
detected in some of the soil samples.

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Table 2.1 Surface and Subsurface Soil Contaminants Greater Than Screening Levels, DP44
Chemical
Detect
Detection Limit
(Ig/kg)
# Analyzed/
# Detected
Concentration
Range (gg/kg)
Location of
Maximum
Anthracene
Benzo(a) anthracene
Benzo (a) pyrene
Benzo (b) f luoranthene
Benzo (g, h, i)perylene
Chrysene
Dibenzo(a, h) anthracene
Indeno(l, 2, 3-cd) pyrene
20
10
9
30
40
70
50
50
4/1
4/3
3/2
4/3
4/3
4/2
4/1
4/3
5500-5500
200-48,000
470-18,000
460-210,000
280-14,000
280-21,000
6500-6500
270-15,000
44M03
44M03
44M03
44M03
44M03
44M03
44M03
44M03
Groundwater contaminants in samples collected from monitoring wells that are greater than
EPA risk-based screening levels or background concentrations for DP44 are summarized in
Table 2.2. During field investigations at DP44 prior to 1994, benzene and TCE were found
in the groundwater above their 5 Ig/L maximum contaminant levels (MCLs). Toluene,
ethylbenzene. and xylene were also detected, but at concentrations below their MCLs.
Benzene contamination above 5 Ig/L covered an area of approximately 3300 m 2 (3947 yd 2),
with Well 44M02 displaying the highest benzene concentration. Groundwater probe data
collected in 1988 indicated that benzene concentrations up to 4000 Ig/L existed near the
top of the water table. Benzene concentrations detected in 1990 had diminished fourfold
since the 1988 sampling. By 1992 and 1994, benzene levels decreased to just above the MCL.
For details on 1992 and 1994 benzene concentrations at DP44, refer to Figures 6.4 and 6.5
in the OU3,4,5 ROD. The 1992 data were used in the risk assessment and are reported in
Table 2.2 and Appendix A of the OU 3, 4, 5 ROD. Two areas of TCE contamination were
detected in the groundwater above the 5 Ig/L MCL, including Well 44M03 and Well 44M04,
with TCE concentrations above 100 Ig/L in Well 44M04. The two sites of TCE contamination
appeared to be unrelated and relatively limited, based on groundwater probe results, which
showed no detectable TCE between the sites or at adjacent probes or wells. The
distribution of contamination near Well 44M04 indicated the source of TCE may be
upgradient of DP44.

In August 1994, TCE and total DCE were still present in the vicinity of Well 44M04 in
concentrations similar to previous years. These concentrations, as shown in Figures 6.6
and 6.7 in the OU3,4,5 ROD, were 109 ppb and 121 ppb, respectively. Results from the
groundwater probe samples taken during the soil borings, are also shown in Figures 6.6 and
6.7 in the OU3,4,5 ROD. They also show that chlorine solvent contamination extends away
from Well 44M04 to the west under the aircraft parking ramp and to the north toward the
hangar. The distributions for TCE and DCE are slightly different. Vinyl chloride has never
been detected in any of the groundwater samples from DP44. No groundwater samples are
available from underneath the hangar. Wells 44M03, 44M07, and 44M08, to the north of the
hangar, show low levels of TCE and DCE contamination. The concentrations in all three
wells are below MCLs. It is not known whether this contamination results from a second
low-level source or is the leading edge of a plume located underneath the hangar. The
total area of TCE-contaminated soils is approximately 6500 M 2 (69,000 ft 2) with a volume
of 20,000 m 3 (25,500 cu yd) containing, an estimated 3.2 kg of TCE.

All contaminants detected at DP44 were in agueous form. No free-phase solvent or fuel was
encountered. This data in addition to a more detailed accounting of the sampling history
and analytical results can be found in the OU 3, 4, 5 ROD and the OU 3,4,5 Remedial
Investigation (RI).

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     Table 2.2 Groundwater Contaminants Greater Than Screening  Levels, DP44
Chemical
Benzene
Trichloroethene
Detection Limit
Ig/L)
2
1
# Analyzed/
# Detected
15/2
15/3
Concentration
Range (Ig/L)
3.7-5.3
1.2-2500
Location of
Maximum
44M05
44M04
2.1.2 The Selected Remedy for DP44 as Originally Described in the OU 3,4,5 ROD

The original selected remedy for DP44 was soil vapor extraction/groundwater
monitoring/institutional controls. This alternative was originally chosen because of its
effectiveness for treating chlorinated solvents that are found at this source area and
because it was believed that SVE would reduce risk to human health and the environment
sooner than monitoring and institutional controls alone. Groundwater extraction and
treatment/SVE was not the preferred alternative because of its difficult implementation,
and because biodegradation, dispersion, dilution, and adsorption appear to be effectively
containing and degrading the contamination.

The primary components of the original selected remedy were:

•      Installation of a soil vapor extraction system to remove solvent contamination in
       soil posing a threat to groundwater through leaching.

•      Implementation of institutional controls,  as described,  to prevent exposure to
       contaminated groundwater.

•      Monitoring of the groundwater to evaluate contaminant levels and identify changes to
       contaminant plume configuration until remediation levels are achieved.

The original ROD also Stated that it could become apparent, during the design phase,
implementation, or operation of the SVE system that solvent and fuel-related compounds in
the soil and groundwater had declined or had fallen below levels that would pose an
unacceptable risk. In such cases, the system performance standards or the remedy would be
re-evaluated to allow for the contaminants to naturally degrade.

2.1.3 Amended Selected Remedy

In summer 1995, the Air Force conducted a pilot scale vapor extraction test to evaluate
the rate of contaminant removal. The test results showed very low removal rates indicating
that the contaminant concentration in soil is low. Contaminant concentrations in extracted
vapors also confirmed that the mass of solvents in the subsurface soil is small.

Since the source of contamination is small, little additional contamination is expected to
enter the groundwater from the soils; therefore,  contaminant concentrations are expected
to decrease through natural process. The area of contamination is limited to an area of
approximately 600 feet and does not appear to be expanding.

The additional investigation and pilot testing described above indicate that contamination
is being addressed through natural attenuation and biodegradation in both the soils and
groundwater; therefore, the original remedy of soil vapor extraction is proposed to be
changed as follows:

•      Residual soil contamination is not expected to act as a continuing source of
       groundwater contamination. No further action of soils under CERCLA is proposed.

•      Continued monitoring and evaluation to confirm that the groundwater contamination is
       not migrating; and that contamination levels are continuing to decrease.

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       Implementation of institutional controls to prevent exposure to contaminated soil
       and adjacent to the source area and showed 0.4 mg/kg of DDD DDT concentrations were
       lower,  at 0.097 mg/kg.  In 1990, a sediment sample (62S04)  was collected from the
       slough adjacent to SS35 just upstream of the pond.  In that sample,  DDT and DDD were
       62.4 and 58.6 mg/kg,  respectively.

Table 2.3
Chemical

4,4' -DDD
4,4' -DDE
4,4' -DDT
Aldrin
Alpha-BHC
Clordane
Heptachlor
Surface and Subsurface Soil
Detection Limit
(Ig/kg)
1
N/A
20
1
10
2
Epoxide N/A
Contaminants Greater
# Analyzed/
# Detected
23/18
23/21
23/22
4/1
8/1
23/8
8/1
Than Screening Levels ,
Concentration
Range (Ig/kg)
0.4-58,500
0.09-19,000
4-396.000
6.2-6.2
17-17
3-410
13-13
SS35
Location
Maximum
35SS03
35DIR05
35SS03
35M01
35DIR05
35DIR06
35DfR05

of
Detect







Groundwater contaminants greater than EPA risk-based screening levels or background
concentrations for SS35 are summarized in Table 2.4. In 1992, the measured concentrations
of PCBs and DDT and its derivative products 4,4'-DDD and 4,4'-DDE were at or below their
reported limits of detection.
      Table 2.4 Groundwater Contaminants Greater Than Screening Levels, SS35

Chemical
1,2-
Dichloroethane
4.4'-DDT
Benzene
Beta-BHC
Detection Limit
   (Ig/L)

   0.5

    0.1
     2
   0.05
 # Analyzed/
# Detected

   12/1

   13/2
   12/1
   13/1
Concentration
Range (Ig/L)
 0.14-0.16
  3.5-3.5
 0.05-0.05
Location of
Maximum

 35GP03

 35GP02
 35GP03
 35GP01
This data in addition to a more detailed accounting of the sampling history and analytical
results can be found in the OU 3, 4, and 5 Record of Decision (ROD) and the OU 3,4,5 RI

2.2.2 The Selected Remedy for SS35 as Originally Described in the OU 3, 4, 5 ROD

The selected remedy as presented in the OU 3, 4, 5 ROD was a combination of Alternative 3
(Soil Cover) and Alternative 4 (Possible Removal of Drums),  and was determined at the time
the ROD was signed to be the most appropriate remedy for source area SS35. The placement
of a clean soil cover was intended to prevent contact with pesticide-contaminated soil and
to prevent runoff of contaminated soil into Garrison Slough. The buried drums were to be
left in place and the groundwater, surface water, sediments, and aguatic organisms
monitored, as appropriate. Excavation of the contaminated soil and drums was not
considered to be cost-effective.

The cover alternative focused on minimizing DDT migration into Garrison Slough and
eliminating the surface soil exposure pathway. The cover was selected for those areas
where DDT was detected above the residential risk-based levels in the surface soil. The
soil cover was selected primarily for the purpose of limiting the migration of
contaminants into Garrison Slough and to prevent direct soil contact and ingestion by the
base personnel and ecological receptors.
The primary components of the original selected remedy were:

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• Installation of a soil, cover over the surface soil contamination to prevent direct
contact by humans, animals, and surface water runoff into Garrison Slough;

• Removal of drums in the future, if it was determined that they are a continuing
source of contamination;

• Monitoring of surface water, sediments, and aguatic organisms in this area, as
reguired to verify effectiveness of the cover and monitoring of the groundwater to
verify that levels remain below acceptable screening levels.

2.2.3 Amended Selected Remedy

Further evaluation of the sampling data indicated that the contaminant concentrations
averaged over this relative area do not pose an unacceptable risk to human health or the
environment. The maximum concentration found for pesticides did indicate a potential human
health risk if this area were developed for residential use in the future. However, these
maximum concentrations were isolated and were not consistent over the area. In addition,
the potential for residential development in this area is very low. Therefore, additional
soil cover is not necessary for protectiveness; the current soil cover is protective of
both human and ecological receptors (OU3,4,and 5 Conceptual Design, 1996, page 15). The
Final Sitewide Biological Risk Assessment was completed in May 1995 after the original ROD
was signed. Based on new information in this report, the ecological risk for this source
area indicated a environmental hazard guotient (EHQ) <1 for all summed pathways. The clean
soil cover alternative was originally selected in part because it would mitigate
ecological risk. Because the Sitewide risk work indicated that current ecological risk is
not unacceptably high, the cover is not needed to mitigate ecological risk.

The concern with respect to surface water runoff into the slough was also re-evaluated.
The area is covered with grass and is relatively flat with little expected soil erosion.
In addition, the concentrations in the soils do not differ significantly from those found
in the slough sediment: therefore, any surface water runoff that does occur is not
expected to contaminate the sediments or surface water. Surface water and sediments in
Garrison Slough in this area do not pose a risk to human health or the environment.

1991), in 1992 (Shannon & Wilson 1992), in 1993 (U.S. Air Force 1994b), and in 1994 (U.S.
Air Force. 1995 a, b, c).

2.3.1 Contamination Problems

Groundwater contaminants greater than EPA risk-based screening levels or background
concentrations for ST58 are summarized in Table 2.6. Investigations conducted during the
fall of 1991 and winter of 1992 indicated that benzene concentrations in the groundwater
downgradient of source area ST58 were greater than the drinking water standard. Toluene,
ethylbenzene, and xylene were also detected.

In April 1993, groundwater samples were collected from the same wells. Benzene
concentrations above drinking water standards were again found in several locations.
Toluene and total xylenes were also detected. Gasoline-range petroleum hydrocarbons at a
concentration of 200 Ig/L were detected in one well. Diesel-range petroleum hydrocarbons,
ranging in concentrations from 0.1 to 99 Ig/L, were detected in 9 of 12 wells. Samples
were analyzed for lead and it was found in concentrations above the EPA action level (15
Ig/L) in all of the source area wells.

A follow-on investigation was conducted in the fall of 1994. Lead and benzene
concentrations in the groundwater remain above the drinking water standard. The extent of
benzene and lead contamination is shown in Figures 7.15 and 7.16 of the OU3,4,5 ROD.

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All contaminants detected at ST58 were in aqueous form. No floating product was
encountered, but it is likely that past fuel releases resulted in transient product plumes
that have since dissipated after the service station was closed and the buried supply
pipeline removed from service.

Table 2.5 Groundwater Contaminants Greater Than Screening Levels, ST58
Chemical

Benzene
Gasoline
Lead
Detection Limit
(Ig/L)
5
2000
5
# Analyzed/
# Detected
13/6
14/1
14/13
Concentration Range
(Ig/L)
3.7-180
261,000-261,000
35-180
Location of
Maximum
58MW09
58MW09
58MW12
This data in addition to a more detailed accounting of the sampling history and analytical
results can be found in the OU 3, 4, 5 ROD and the OU 3,4.5 RI.

2.3.2 The Selected Remedy for ST58 as Originally Described in the OU 3, 4, 5 ROD

At site ST58 Alternative 3, an in situ alternative consisting of bioventing/groundwater
monitoring/institutional controls, was determined to be the most appropriate remedy at the
time the OU 3, 4, 5 ROD was signed. This alternative was selected to reduce the fuel
source in the soils through degradation of fuel hydrocarbons, and thus reduce the risk to
human health and the environment sooner than with monitoring and institutional controls
alone. At the time the OU 3, 4, 5 ROD was signed, no proven method was known for removing
lead from groundwater at a reasonable cost in a reasonable amount of time. However, a
treatability test was being performed at another site ST 13/DP26 at Eielson AFB to
determine the fate and transport of lead and the most viable option for extraction and
treatment. Results from the treatability study were to be used to further evaluate lead
remediation at ST58. Groundwater extraction/bioventing (Alternative 4) was not the
preferred alternative because of its difficult implementation, and because biodegradation,
dispersion, dilution, and adsorption appear to be effectively containing and degrading the
contamination.
Alternative 3 was selected to reduce the long-term source of contamination by
preferentially encouraging the removal of contaminants from the soil through bioventing.
Groundwater action consisted of natural attenuation, institutional controls, and
monitoring.

The primary components of the original selected remedy were:

• Installation of a bioventing system to remove fuels contamination in the soil that
poses a threat to groundwater through leaching.

• Institutional controls to prevent exposure to contaminated groundwater.

• Monitoring of groundwater to evaluate contaminant level and identify changes to
contaminant plume configuration until remediation levels are achieved.

2.3.3 Amended Selected Remedy

Because of the 1993 removal of 700 cu. yd. of BTEX contaminated soils from the most
contaminated area of the site, the level of remaining residual soil contamination does not
appear to warrant installation of a bioventing soil treatment system. New information that
was not available in September 1995 when the OU 3,4,5 ROD was signed has been considered
during the RD for source area ST58. The new information includes groundwater and soil
vapor chemistry data collected by EA Engineering in September 1995. The results are shown
in Figure 3-18 (OU3,4,5 Draft RD, 1996 ), and indicate that the BTEX concentrations in the
groundwater at the source are present at concentrations approximately an order of

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magnitude lower than the concentrations presented in the RI/FS and ROD which supported the
selection of the in situ alternative over the groundwater monitoring/institutional
controls alternative. The 0 2/CO 2 data collected in the vadose zone of the source area
indicate that the soil vapor does contain relatively low concentration of 0 2,  and
relatively high concentration of CO, suggesting that natural respiration of hydrocarbons
is occurring. The results of the EA data gap work also indicate that the BTEX plume is
less extensive now than it was when the samples were last collected in 1993 (Figures 3-16
& 3-17) , and the one well that contained benzene in 1995 (58MW10)  had decreased its
concentration over an order of magnitude from that of the 1993 sampling. Benzene
concentrations are below 100 Ig\L, the concentration used for the OU1 and OU2 bioventing
remediation efforts to delineate the area to be remediated. Some of the decrease in the
size of the dissolved plume is attributed to the removal of some of the hydrocarbon source
when 700 cu.yd. of soil was excavated from the former tank Pit in 1993  (Liikala & Evans,
1995). However, no soil was removed in the area of the monitoring well 58MW10.  This data
seems to support the conclusion that both source removal and natural attenuation have
significantly reduced the area of the groundwater impacted by benzene at ST58.  Natural
attenuation of the hydrocarbons at the source area is occurring based on the groundwater
monitoring results collected by EA and based on the results of the testing completed by
Utah Water Research Laboratory for the area of ST13/DP26.

Alternative 2, Institutional Controls, will be selected instead of Alternative 3, In Situ.
This change could be considered a fundamental change that is a logical outgrowth of data
gap work and scoping conducted during the RD.

Additional investigations have indicated that petroleum contamination is being addressed
through natural attenuation and biodegradation in both the soils and groundwater; and
therefore, the original remedy of bioventing is proposed to be changed as follows:
Residual soil contamination does not appear to be adversely impacting the groundwater;
therefore, no further action of soils is proposed. For the lead contamination at ST58, the
Air Force, EPA, and ADEC have determined that groundwater restoration for this confined
area is technically impracticable. Subseguent to the ROD, the Air Force conducted an
extensive study of the groundwater lead contamination at the base to determine the form of
the lead and to determine if the area of lead contamination was expanding. 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 conseguently, 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 the 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 contamination migration;  (2)
source removal to prevent further contamination of the groundwater and  (3) prevention of
exposures. For ST58, the Air Force,  EPA, and ADEC 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 groundwater lead contamination is not
       migrating and is remaining within the currently established containment area.
       Regulatory reguirements would be waived for lead contamination in groundwater within
       this limited containment area.




Groundwater sampling results in 1989 delineated plumes of trichloroethane (TCE)  near Well
03M08 and vinyl chloride near Well 03M01. TCE was not detected in samples collected

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downgradient of Well 03M08 and, therefore, is probably caused by a localized leak from
landfill debris. The plume appeared to have originated near Well 03M01 and extended to the
north, toward Garrison Slough. These solvents were most likely derived from leaking
containers of spent solvent in the landfill. Low concentrations of solvents were also
detected in the 1992 groundwater samples.

By the time of the sampling event in August 1994, benzene and chlorinated solvents were
below MCLs (and in many cases below detection limits) in all wells in LF03/FT09, except
for Well 03M08. This well contained relatively high concentrations of a number of
contaminants (see Table 2.8), including 4-methyl phenol (p-cresol),dichlorodifluoromethane
(Freon-11), and trichlorofluoromethane (Freon-12). Analyses were not reported for Well
03M08 in a previous investigation by HLA (1989) because of analytical difficulties. Well
03M08 was not sampled in 1992. This well is located in the eastern portion of LF03 in the
area of the waste trenches, which were used after 1980. It is important to note that
contaminated groundwater from LF03/FT09 is limited to low concentrations in one well
within the landfill refuse. Groundwater concentrations in wells surrounding the
downgradient perimeter of the landfill are below regulatory levels.

This data in addition to a more detailed accounting of the sampling history and analytical
results can be found in the OU 3, 4,5 ROD and the OU 3,4,5 RI.

2.4.2 The Selected Remedy for LF03/FT09 as Originally Described in the OU 3, 4, 5 ROD

At site LF03/FT09 Alternative 4, Soil Cover/Composite Cap/Groundwater Monitoring/
Institutional Controls, was determined to be the most appropriate remedy at the time the
OU 3, 4, 5 ROD was signed. FT09 is considered together with LF03, because FT09 is
completely contained within LF03.

This alternative was chosen because it is believed that a composite cap was reguired under
RCRA Subtitle C for areas that receive waste after 1980. Groundwater monitoring would be
performed at the edge of the waste management area to detect any movement of contaminants.

The cap alternative focused on eliminating the threat of direct contact with buried
landfill debris and on soil contamination and monitoring of groundwater at the edge of the
waste management area to ensure that federal and State standards are met.

The primary components of the selected remedy were:

• For the portion of the landfill where disposal occurred before 1980, RCRA Part 264
is relevant and appropriate. Currently, no groundwater at the edge of the waste
management area exceeds regulatory levels: the residual contamination poses a direct
contact threat. A cover to address the direct contact threat will be installed and
maintained in accordance with relevant and appropriate reguirements of Part 264.
Groundwater at the landfill will continue to be monitored as appropriate, to verify
that contaminant concentrations, if any remain within acceptable screening levels.

For the portion of the landfill where disposal, occurred after 1980, RCRA Part 264
is applicable. The final cover will be constructed to: (1) provide long-term
minimization of migration of liguids, (2) function with minimum maintenance, (3)
promote drainage and minimize erosion, (4) accommodate settling and subsidence, and
(5) have a permeability less than or egual to the natural subsoil present.
Post-closure care, including maintenance and monitoring, will be conducted in
accordance with 40 CFR 264.117 and 264.228(b).

• Institutional controls will be implemented to restrict land use. In the event of
base closure, any remaining contamination will be addressed in accordance with
CERCLA Section 120.

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2.4.3 Amended Selected Remedy

No fundamental changes are proposed to the selected remedy; however, clarification of
regulatory issues is warranted. The Air Force had previously indicated that there was
documented evidence of disposal of hazardous waste in the post-1980 disposal area. A
subseguent search of Air Force and Fairbanks North Star Borough records after the signing
of the original ROD could not confirm this disposal of hazardous waste. Given the lack of
documentation of hazardous waste disposal, RCRA Subtitle C is relevant and appropriate as
an ARAR, but is not applicable. Groundwater concentrations are below regulatory levels,
therefore, an impermeable cover to prevent movement of groundwater through the landfill is
not warranted. The amended selected remedy is clarified as follows:

• Hybrid Landfill Closure including cover to address the direct contact threat will be
maintained in accordance with relevant and appropriate reguirements of the Resource
Conservation and Recovery Act Part 264 and OSWER Directive 9234.2-04FS, "RCRA ARARs:
Focus on Closure Reguirements".

• Groundwater at and adjacent to the landfill will continue to be monitored to verify
that contaminant concentrations remain below acceptable regulatory levels.

• Institutional controls will be implemented to restrict land use to prevent direct
exposure to landfill waste.

3.0 Summary of Comparative Analysis

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
(NCP).

3.1 Overall Protection of Human Health and the Environment

3.1.1 Site DP44: Both the original and the amended remedies satisfy this criteria. The
amended remedy would use institutional controls to prevent the use of contaminated
groundwater at the site until cleanup standards are achieved and would employ long term
monitoring. The SVE 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 of soil and groundwater over biodegradation and natural
attenuation, as shown by additional investigation and pilot testing.

3.1.2 Site SS35: Both the original and the amended remedies satisfy this criteria. The
amended remedy would employ long term monitoring of surface water, groundwater, sediments,
and aguatic organisms to confirm concentrations of contaminants found at the site remain
at levels protective of human health and the environment.

3.1.3 Site ST58: Both the original and the amended remedies satisfy this criteria. The
amended remedy would use institutional controls to prevent the use of contaminated
groundwater at the site and would employ long term monitoring. Because a significant
volume of BTEX contaminated soil (700 cu. yd.) was removed from the site in 1993 for a
composting demonstration, the limited contaminant source remaining does not appear to be
impacting the groundwater and bioventing at this site will not reduce the contaminant
levels at a significantly greater rate over natural attenuation and biodegradation, as
shown by studies conducted at other sites on the base. Because of the similarity of site
conditions and groundwater lead contamination between site ST58 and sites ST13/DP26, the
decisions reached at site ST13/DP26 regarding the issue of lead contamination in the
groundwater (Technical Impracticability Waiver and monitoring for lead plume stability)
were applied to Site ST58 and are considered protective of human health and the
environment. The Air Force will effectively maintain institutional controls in this area
in accordance with the Institutional Control Plan while contaminant levels exceed
regulatory levels.

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3.1.4 Sites LF03 & FT09: Both the original and the amended remedies satisfy this criteria.
The amended remedy would employ maintenance of the existing landfill cap to prevent
exposure through direct contact with materials buried in the landfill, and institutional
controls to restrict land uses. Long term monitoring of groundwater will continue. Because
it has been verified that materials buried in the unlined landfill are in contact with the
groundwater, and contaminants in the groundwater remain below regulatory levels, the
impermeable cover proposed in the original selected remedy is not considered to provide a
greater level of protection to human health and the environment than the existing soil
cover in place.

3.2 Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)

The ARARs for the amended selected remedy are the same as those for the original remedy
for all source areas.

3.2.1 Site DP44: The amended remedy is expected to achieve groundwater maximum contaminant
goals presented in the original ROD.

3.2.2 Site SS35: The amended remedy complies with all ARARs presented in the original ROD.

3.2.3 Site ST58: The amended remedy is expected to achieve groundwater maximum contaminant
goals presented in the original ROD, with the exception of the action level for lead.
ARARs for lead contamination in the groundwater at this site have been waived under
conditions of the Technical Impracticability Waiver (TIW) from an engineering perspective.

3.2.4 Sites LF03 & FT09: The amended remedy complies with all ARARs presented in the
original ROD.

3.3 Long-term Effectiveness and Permanence

3.3.1 Site DP44: Natural attenuation of hydrocarbon and solvent contaminants in
groundwater has been shown through study at Eielson AFB to aggressively degrade these type
compounds. The amended remedy also prevents use of contaminated groundwater at the site
through use of Institutional Controls. Once groundwater MCLs are met, long-term
effectiveness and permanence will be achieved.

3.3.2 Site SS35: Contaminants found in surface waters , sediments, and aguatic organisms
on this site are not at levels which pose an unacceptable risk to human health and the
environment. Long term monitoring of surface water, sediments, and aguatic organisms will
continue to ensure long-term effectiveness and permanence.

3.3.3 Site ST58: Natural attenuation of hydrocarbon contaminants in groundwater has been
shown through study at Eielson AFB to aggressively degrade these type compounds. In
addition, organic lead in groundwater at the site is expected to degrade to the immobile
inorganic phase. The alternative also prevents use of contaminated groundwater at the site
through use of Institutional Controls.

3.3.4 Sites LF03 & FT09: The amended remedy will prevent digging into the landfill waste
and is effective in isolating the landfill contents. Enforcement of the site Institutional
Controls will ensure long term effectiveness and permanence of the selected alternative.

3.4 Reduction of Toxicity, Mobility, or Volume Through Treatment

3.4.1 Site DP44: Low levels of soil contamination remaining at this source area do not
meet the definition of principal threat. The amended remedy for DP44 does not meet the
statutory preference for treatment as a principal element. Treatment was not practicable
due to the relatively low levels of contamination remaining.

3.4.2 Site SS35: The selected alternative does not include treatment, as the levels of
contaminants at this site do not pose an unacceptable risk to human health and the

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environment.

3.4.3 Site ST58: Low levels of soil contamination remaining at this source area do not
meet the definition of principal threat. The amended remedy for ST58 does not meet the
statutory preference for treatment as a principal element. Treatment for the organic
contamination in soil was not practicable due to the relatively low levels of
contamination remaining.

Treatment of the lead contamination in the groundwater is technically impracticable from
an engineering perspective.

3.4.4 Sites LF03 & FT09: The selected alternative does not include treatment of the waste
because of the low contaminant concentrations and the large volume of waste. The
investigation did not identify "hot spots" of soil or groundwater contamination suitable
for treatment within this large landfill.

3.5 Short-Term Effectiveness

3.5.1 Site DP44: Natural Attenuation is not a short-term cleanup process, and will achieve
cleanup standards much more slowly than active remediation technigues. Neither the amended
remedy or the original remedy pose an unacceptable risk to residents or workers during
implementation. All potential impacts from construction and system operations will be
controlled using standard engineering controls and practices.

3.5.2 Site SS35: Levels of contaminants at this site do not pose an unacceptable risk to
human health and the environment.

3.5.3 Site ST58: Natural Attenuation is not a short-term cleanup process, and will achieve
cleanup standards much more slowly than active remediation technigues. Neither the amended
remedy or the original remedy pose an unacceptable risk to residents or workers during
implementation. All potential impacts from construction and system operations will be
controlled using standard engineering controls and practices.

3.5.4 Sites LF03 & FT09: Neither the amended remedy or the original remedy pose an
unacceptable risk to residents or workers during implementation. All potential Impacts
from construction and system operations will be controlled using standard engineering
controls and practices.

3.6 Implementability

3.6.1 Site DP44: Institutional Controls and long-term monitoring are readily implementable
and can be effectively maintained on this Air Force base.

3.6.2 Site SS35: Long-term monitoring of surface water, sediments, and aguatic organisms
is readily implementable.

3.6.3 Site ST58: Institutional controls and long-term monitoring are readily implementable
and can be effectively maintained on this Air Force base.

3.6.4 Sites LF03 & FT09: Institutional controls and long-term monitoring are readily
implementable and can be effectively maintained on this Air Force base.

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3.7 Cost

3.7.1 Site DP44:

                       Original Alternative Cost  ($000)       New Alternative Cost  ($000)
Soil Vapor Extraction                  1,600                                     0
GW Monitoring/ICs                        140                                   140

Total Cost                             1,740                                   140
3.7.2 Site SS35:

                              Original Alternative Cost ($000)    New Alternative Cost ($000)

Soil cover                               40                                     0
Surface Water/
Sediment/
Aguatic Org. Monitoring                 140                                   140

Total Cost                              180                                   140

3.7.3 Site ST58:

                         Original Alternative Cost  ($000)      New Alternative Cost  ($000)

Bioventing System                      51                                        0
GW Monitoring/ICs                     140                                      140

Total Cost                            191                                      140


3.7.4 Sites LF03 & FT09:

                         Original Alternative Cost  ($000)       New Alternative Cost  ($000)

Soil cover & components                  7100                                     0
GW Monitoring/ICs                          230                                  230

Total Cost                               7,330                                  230

3.8 State Acceptance

The State of Alaska Department of Environmental Conservation (ADEC) concurs with the
actions selected in this ROD amendment.

3. 9 Community Acceptance

No public comments were received, regarding the Proposed Plan,  during the public meeting
held May 23, 1996, or during the public comment period from May 13, 1996 through June 12,
1996. Community participation is discussed in Section 8.0, Responsiveness Summary.

4.0 Technical Impracticability of Groundwater Restoration

4.1 Specific ARARs

The specific ARAR or media cleanup standards for which the TI waiver applies are as
follows:

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• 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).

The 71 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.

4.2 Spatial Extent of TI Waiver

The TI waiver will apply to the area having the following boundaries (see Figure A).

• Wabash Avenue on the east
• Division Street on the south
• Flightline Avenue on the west
• A line running east and west along, the south side of the Air National Guard
operations building #3129.

The vertical extent of the TI waiver will range from the water table to 30 feet below the
average annual water table depth.

4.3 Conceptual Model

4.3.1 Site Conditions

The information presented below is from the MR for Site ST13/DP26. Because of the
similarity in site conditions and lead contamination between Site ST58 and Site ST13/DP26,
the U.S. Air Force, EPA. and ADEC agree that conclusions reached in the ITIR for Site
ST13/DP26 can be applied to Site ST58. The information presented below is from the ITIR,
as follows:

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 deposition 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 aguifer 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 aguifer 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).

4.3.2 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 and
appears to coincide with the historic extent of the floating product plume. During the
investigation, tetraethyl lead (TEL) , the 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 gualified 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

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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 aguifer restoration would reguire
approximately 100 years. This prediction is also very uncertain for the reasons Stated
above.

4.3.3 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 aguifer 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 guickly 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
limits of the lead contamination plume. After the fuel source is removed and
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.

4.4 Evaluation of Restoration Potential

4.4.1 Source Control Measures

The 1998 removal of the four 25,000 gal. above-ground storage tanks and associated piping
used for the storage and handling, of leaded and unleaded motor gasoline MOGAS) and diesel
removed the primary source of fuel and lead contamination at the Motor gasoline (MOGAS)
and diesel stored and used at the Quartermaster Service Station appears to have been
spilled or leaked from the piping and diesel tanks during operations at the facility. In
1993, approximately 700 cu.yd. of fuel contaminated soil was removed from the most highly
contaminated area of the site and used in a composting study (U.S. Air Force, Operable

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Units 3.4. and 5 Final Record of Decision, September 1995, page 7.11). All contaminants
detected at ST58 are in the aqueous form, with no floating product encountered at the site
(U.S. Air Force, Operable Units 3,4, and 5 Final Record of Decision, September 1995, page
7.12). After decommissioning of the Quartermaster Service Station in 1988, no fuels have
been stored at this site.

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
and that 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 to remove the residual contamination is not practical
because the majority of the contamination is within the saturated zone (U.S. Air Force
1994),

4.4.2 Restoration Timeframe

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 could be significantly longer. The EPA review also Stated that the lead is relatively
immobile and cannot be cleaned up using pump and treat technology.

5.0 Institutional Controls

As part of the institutional controls for contaminated soil and groundwater, the Air Force
will develop a written, installation-wide plan ("Institutional Control Plan" or "1C Plan")
that sets out procedures to assure that institutional controls for soil and groundwater
are developed, maintained, monitored, and remain effective. The 1C Plan will be completed
within six months of the signature of the ROD amendment and will apply to all areas on the
base, including those listed in this ROD Amendment, requiring institutional controls for
soil and groundwater as part of the remedy. The 1C Plan will be reviewed and approved by
EPA and the State of Alaska and is enforceable jointly or severally by them.

The 1C Plan shall specify the following:

1.) Eielson AFB will undertake, at a minimum, the following:
a. identify all areas under restriction or control;
b. identify the objectives that must be met by the restrictions and
controls;
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 Institutional Control ("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 State, 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

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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 reguired.

3.) The 1C Plan will specify that all current or future land users, whether
government or private entities will be legally reguired 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 reguired by
the 1C process at the installation.

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 freguency 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 reguirements. 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 reguires the
correction to be implemented.

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       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 approval by 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.

 6.6 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 reguirements
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
reguirement 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.

Because these remedies will result in hazardous substances remaining onsite above
health-based levels, reviews will be conducted at sites DP44, ST58, and LF03/FT09 each 5
years during the five-year ROD review process to ensure that the remedies continue to
provide adeguate protection of human health and the environment.

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7.0 Responsiveness Summary

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 Record of Decision Amendments for Operable
Unit 2 and Operable Units 3, 4, 5 which was released to the public in May 1996 and
discussed in a public meeting on 23 May 1996. The proposed ROD amendment document outlined
proposed changes to the selected remedies for addressing soil and groundwater
contamination in the Records of Decision for OU 2 and OU 3, 4, 5. The public comment
period for the Proposed Plan was from May 13 to June 12, 1996.

These sections follow:

•      Background on Community Development
•      Summary of the Comments Received During the Public Comment Period and USAF responses
•      Remaining Concerns

7.1 Background on Community Involvement

Prior to the addition of Eielson AFB to the EPA National Priority List in 1989, the
community was offered little opportunity for involvement in environmental activity. From
1982 until 1989, the USAF used the Installation Restoration Program  (IRP) to identify
potential contaminated areas and investigate what remedial actions might be reguired. This
process was purely technical and did not evaluate community concerns in the
decision-making process. However, after signing a Federal Facility Agreement with the
State of Alaska and the EPA in 1991, the Air Force began its Superfund clean up program,
which does include extensive community involvement.

A Technical Review Committee  (TRC), established in 1992, included three representatives
from the community (selected by local officials and the University of Alaska Chancellor),
industry representatives, and environmental representatives. Many of the TRC participants
are members of the professional public. 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 ROD amendments.

The public comment period, public meeting and proposed 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. 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
at the areas identified in Section 1.5.

7.2 Summary of Comments Received During the Public Comment Period and USAF Responses

A public meeting was held on May 23, 1996 at the North Pole City Hall in North Pole,
Alaska.  Approximately 25 people attended the meeting, including representatives of the Air
Force, EPA, ADEC, and the public. The public comment period on the Proposed Plan extended
from May 13 through June 12, 1996. There were no formal verbal comments received during
the public meeting or during the public comment period.

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8.0 References

Harding Lawson Associates (HLA). 1989. Installation Restoration Program Remedial
Investigation/Feasibility Study, Stage 3, #2, Eielson Air Force Base, Alaska. Volume 111,
Draft Remedial Investigation/Feasibility Study (July 1988-April 1989, Chapter IV. Ad.
Record 1390, Prepared by Harding, Lawson Associates for the Alaskan Air Command, Elmendorf
Air Force Base, Alaska.

Harding Lawson Associates (HLA). 1990. Installation Restoration Program Remedial
Investigation/Feasibility Study, Stage 4, Draft Report for Eielson Air Force Base, Alaska.
Volume I through V. Prepared by Harding, Lawson Associates for the Alaskan Air Command,
Elmendorf Air Force Base, Alaska.

Liikala, T. L., and J. C. Evans. 1995. Field Investigation, Source Area ST58, Old
Quartermaster Service Station, Eielson Air Force Base, Alaska PNL-10358, Pacific Northwest
Laboratory, Richland, Washington.

Shannon & Wilson. 1991. Geotechnical Investigation and Foundation Study Vehicle
Maintenance Facility Air National Guard Eielson Air Force Base, Alaska. Shannon & Wilson,
Inc. Fairbanks. Alaska.

Shannon & Wilson. 1992. Final Report Alaska Air National Guard UST Removal Building
6128, Eielson Air Force Base, Alaska. Shannon & Wilson, Inc. Fairbanks, Alaska.

U.S. Air Force. 1993b. Eielson Air Force Base OU-2 Remedial Investigation/Feasibility
Study: Remedial Investigation Report. Eielson Air Force Base, Alaska.

U.S. Air Force. 1994b. Source Evaluation Report Phase 2 Investigation Limited Field
Investigation Final Report. Eielson Air Force Base, Alaska.

U.S. Air Force. 1995. Environmental Restoration Program, Sitewide Biological Risk
Assessment (Final), Eielson Air Force Base, Alaska.

U.S. Air Force. 1995. Operable Units 3,4, and 5 Record Of Decision (Final), Eielson Air
Force Base, Alaska.

U.S. Air Force. 1995a. Environmental Restoration Program, Overable Units 3,4, and 5
Remedial Investigation Report (Final), Eielson Air Force Base, Alaska.

U.S. Air Force. 1995b. Environmental Restoration Program, Operable Units 3,4, and 5
Baseline Risk Assessment (Final), Eielson Air Force, Alaska.

U.S. Air Force. 1995c. Environmental Restoration Program, Operable Units 3,4, and 5
Feasibility Study (Final), Eielson Air Force Base, Alaska.

U.S. Air Force. 1996. Eielson Air Force Base Operable Unit 2, Source Areas ST13/DP26,
Treatability Study Informal Technical Information Report. Air Force Center for
Environmental Excellence, Brooks Air Force Base, Texas.

U.S. Air Force. 1996. Operable Units 3,4, and 5, Conceptual Design, Eielson Air Force
Base. Alaska.

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