FINAL

SUPERFUND PRELIMINARY CLOSEOUT REPORT

Ellsworth Air Force Base

Rapid City, South Dakota

I. INTRODUCTION

This Preliminary Close Out Report (PCOR) documents that Ellsworth Air Force Base (EAFB)

has completed all construction activities, and that the remedies are operational and functional,

for the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as

amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986, in

accordance with OSWER Directive 9320.2-3C. Twelve operable units (OUs) were identified at

EAFB. None of the Record of Decisions (RODs) were contingency RODs. Final Regulatory

Inspections were conducted from July 1996, through January 1998, at the OUs. US Army Corps

of Engineers contractors constructed the selected remedies in accordance with the respective

remedial design (RD) plan and specifications.

II. SUMMARY OF SITE CONDITIONS

A. Background

Ellsworth AFB is located 12 miles east of Rapid City, South Dakota, and adjacent to the small

community of Box Elder. Ellsworth AFB was officially activated in July 1942 as the Rapid City

Army Air Base. It became a permanent facility in 1948, with the 28th strategic Recormaissance

Wing as its host unit. Throughout its history, EAFB has been the base of operations for a

number of types of aircraft and missile systems. Presently, the 28th Bombardment Wing

(B 1-bombers) is the host unit.

The main Air Base covers 4,858 acres within Meade and Peunington Counties. The Base

includes runways, airfield operations, industrial areas, and housing and recreational facilities.

Open land, containing a few individual residences, lies to the north, south, and west of EAFB,

while residential and commercial areas lie to the east.

Twelve OUs were identified at EAFB. In addition, the South Dakota Department of

Environment and Natural Resources (SDDENR) provides oversight for several petroleum

release sites, which are not addressed under CERCLA. Ground-water extraction systems are in

operation to address ground-water contamination associated with the JP-4 plume and the •

Flightline Refueling Area (FRA).

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Operable Unit 1

OU-1 contained the Former Fire Protection Training Area (FPTA) and is located on the

southwest portion of EAFB northwest of the alert apron and east of Kenny Road. OU-1 covers

approximately ten acres and consisted of a centrally located, unlined, bermed burn pit, a steel

aircraft mockup and surrounding land. The burn pit area was the source area of contamination.

Soils at OU-1 contained JP-4 (jet fuel); benzene, toluene, ethylbenzene, xylenes (BTEX); and,

chlorinated volatile organic compounds (VOCs). JP-4 concentrations were much higher than

other compounds. Ground water at OU-1 contained chlorinated VOCs, BTEX and JP-4. Light

non-aqueous phase liquids (LNAPLS) were present in the northern and southern end of the

FPTA. Dense non-aqueous phase liquids (DNAPLS) were not present at OU-1. Ground-water

contamination in this area did not extend beyond the Base boundary.

Operable Unit 2

The OU-2 study area consisted of former Landfill No. 1 (21.5 acres), former Landfill No. 6

(0.5 acres), a drainage channel in the western portion of Landfill No. 1 and a drainage channel

near Landfill No. 6 which included Pond 002.

Within OU-2, soils contained chlorinated VOCs, BTEX, and polynuclear aromatic hydrocarbons

(PAHs). All but one of the reported concentrations in soil was below the 10.6 risk based level

calculated for excess carcinogenic risks. Monitor wells installed in the interior of Landfill No. 1

indicated the presence of TCE and DCE in five samples at maximum concentrations of 14 lag/L

and 19 pg/L, respectively.

JP-4 contamination caused by a leak in a fuel line was identified along the southern boundary of

OU-2. This JP-4 contamination is being remediated under the SDDENR petroleum release

program.

Operable Unit 3

OU-3 is located in the northeast portion of EAFB and consisted of former Landfill No. 2 (one

acre), four trenches to the north, and two disturbed areas in the southeast and southwest corners

of the OU.

Soil and soil vapor samples from OU-3 indicated the presence ofVOCs, BTEX, methane (soil

vapor only) and semi-volatile organic compounds (SVOCs) (soil only). The calculated

carcinogenic risk level for surface soil was 1 x 106, due to the presence of SVOCs. This was

within the acceptable range.

Ground-water samples indicated the presence of chlorinated VOCs and petroleum constituents.

The calculated carcinogenic and non-carcinogenic risks for ground water exceeded the

acceptable carcinogenic and non-carcinogenic risk ranges.

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Operable Unit 4

OU-4, which includes Landfill No. 3, is a 40-acre site located south of the aircraft control tower

in the southwestern portion of the Base.

Soil at OU-4 contained elevated VOCs, SVOCs, and pesticides within the EAFB boundary.

Ground water contained chlorinated VOCs, SVOCs, and pesticides. Contaminated ground water

within this OU moved from the landfill, located within the original Base boundaries, to an

adjacent area within the OU, which is now owned by the Air Force.

Operable Unit 5

OU-5 included the area surrounding and including Landfill No. 4, a ten-acre site near the

northern perimeter of EAFB.

Polynuclear aromatic hydrocarbons (PAHs) at estimated values below the sample quantitation

limit (48 _g/kg to 250/ag/kg) and JP-4 jet fuel, in one surface soil sample (SB930502) at 190

mg/kg, were reported in soil samples collected from OU-5. Jet fuel was also reporteci at a

concentration of 100 _g/L in one ground-water sample collected during the investigation.

Operable Unit 6

OU-6 consisted of Landfill No. 5, which is approximately seven acres in size and is located near

the southern end of EAFB.

Polynuclear aromatic hydrocarbons and pesticides were reported in soil samples collected from

OU-6. Levels of VOCs and metals contaminants observed in the ground water at the site were

below Maximum Contaminant Levels (MCLs) or considered to be representative of background

levels.

Operable Unit 7

OU-7 included the Low-level Radioactive Waste Burial site located in the Weapons Storage

Area (WSA) at the northern end of the Base. The WSA covers approximately 65 acres and is

currently active. The site contained five underground tanks, which were designed to hold

equipment washdown water. The record search for the OU-7 investigation found no evidence

that these tanks were ever used for the purpose of holding washdown water containing

radioactive materials. The tanks were emptied of water in 1993. In order to sample the soils

surrounding the tanks, the tanks were removed and disposed.

Scattered detections of VOCs were reported in surface soil samples at OU-7; concentrations

were below 10.6 risk based concentrations for Human Health Risks. Radionuclides were

determined to be present within the normal background range due to natural variations in soil

types and geological characteristics.

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Operable Unit 8

OU-8 consisted of two distinct areas of investigation, the Explosive Ordnance Disposal (EOD)

Area and the Debris Burial Area. The EOD site study area included a Pramitol spill area,

burning pit area, burn furnace area, and a detonation site.

Volatile organic chemicals and SVOCs were detected in ground water during the remedial

investigation (RI). The reported concentrations of these contaminants were less than ,orequal to

2 _ag/1.No MCLs or EPA risk-based concentrations exist for the reported contaminants.

Antimony and selenium were reported above the MCL in one or more ground-water samples.

Toluene was the only VOC detected in soil samples collected in the EOD area during the RI.

PAHs and phthalates were also detected in the soil. PAHs typically result from incomplete

combustion of organic materials. Dioxins in the soil correlated with combustion activities in the

EOD area. Dioxin concentrations were low, well below action levels of 1,000 picogr.ams/KG

(pg/KG) for residential soils. The risk assessment for OU-8 indicated that there are no

unacceptable non-carcinogenic or carcinogenic risks at the OU under current land use'.

conditions, resulting from activities conducted at OU-8.

Operable Unit 9

OU-9 consisted of the Old Auto Hobby Shop and the surrounding area and was approximately

90 acres in size. There was no documentation of a major spill or release at OU-9. However,

small volumes of fuels, oils, and solvents may have been released to the environment over time.

Low concentrations of VOCs, primarily BTEX, were found in soils. BTEX and chlorinated

VOCs were detected in ground water. Because an upgradient source was suspected, groundwater cleanup was addressed in OU-I 1 (the Basewide ground-water Operable Unit).

Operable Unit 10

OU-10 was the North Hangar Complex, a 75-acre site located in the central portion of the Base.

The area contains a system of underground jet-fuel hydrant lines that deliver fuel to clocking

aircraft and underground industrial waste lines associated with aircraft maintenance. Organics

reported in soil samples included VOCs, SVOCs and jet fuel. The predominant VOCs were

BTEX compounds. Ground-water contamination associated with OU- 10 was addres.sed within

OU-11 (the Basewide ground-water Operable Unit) for remediation.

Operable Unit 11

This is the Basewide ground-water Operable Unit. Remedial investigation/feasibility study

(RI/FS) and remedial actions (RAs) were developed for those areas of the Base that we, e not

part of the other specific Operable Units. To facilitate project planning, OU-11 was divided into

two parts, Area 1, and Area 2. Areas of ground-water contamination at OU-9 and OU-10 were

addressed within OU-11 as Area 1. Contaminated ground water in Area 1 lies entirely on-Base.

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Volatile organic compounds, SVOCs, and petroleum hydrocarbons were detected in groundwater samples from the South Docks Area. Trichloroethene (TCE) was the most frequently

reported compound in the ground-water samples along with its breakdown products.

Area 2 includes the areas where ground-water contamination has moved off-Base along the

eastern boundary. Off-site contamination associated with these areas has also been referred to as

Area Of Concern 24 (AOC-24). The contaminant of concern associated with Area 2 is TCE and

its associated break down products.

The ground water at OU-11 also was impacted by petroleum releases associated with refueling

of airplanes at the flightline refueling area (FRA). No commingling of hazardous substances

occurred at this site, therefore; remediation activities associated with the FRA are addressed

under the SDDENR petroleum release program.

Operable Unit 12

OU-12 was located in the southem half of EAFB, immediately north of the Alert Apron and

southwest of the runway. OU-12 was designated as Hardfill No. 1, which was approzdmately 14

acres in size. This landfill received building and road demolition rubble from maintenance and

repair activities on the Base. Historical records indicated that the landfill was used for disposal

of this demolition rubble only, and did not receive hazardous wastes. The investigation showed

the presence of VOCs, SVOCs, jet fuel and pesticides, but through site characterization it was

found that these contaminants were related to flightline runoff rather than landfill disposal

practices. Levels of contaminants observed in the ground water at the site were below

Maximum Contaminant Levels. A single upgradient well reported TCE in a ground-water

sample at a concentration of 7 pg/L. The risk assessment for OU-12 indicated that the total

carcinogenic site risk is within the acceptable risk range for the residential scenario and is less

than 1 x 10.6for the industrial scenario.

B. Remedial Construction Activities

The following sections describe the remedial construction activities completed for each OU at

EAFB. A Punch List is included in Appendix A (as shown below):

All OUs

• Modifications to the existing RA systems for Operation and Maintenance.

• Long Term Monitoring Plan to assess the efficiency of the systems.

• Provide continual evaluation of the protection to the environment

These activities will need to be completed to achieve the remedial action objectives established

in the RODs. As part of the operations and maintenance activities, remediation or treatment

systems may be adjusted or modified to ensure they continue to operate and/or maintain the

long-term effectiveness or integrity of the actions selected in the ROD.

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The selected remedies at several of the operable units include Institutional Controls consisting of

a Continuing Order from the Base Commander and the incorporation of the RODs into the real

property records of the Base. A Continuing Order is a one-time order that remains in effect

unless specifically rescinded by the Base Commander or the Commander's superior.

Modification to this continuin_ order can only be made with concurrence from the regulatory

agencies. The Continuing Order details the limitations to property uses and construction

activities until the remedial action goals specified in the ROD have been achieved. At no time

can the Commander's Continuing Order alter or void the remedy selected in the ROD. The Base

has instituted a construction evaluation process that requires proposed construction to be

re_;iewed for conflicts with the selected and implemented remedy at the Operable Units. This

process includes the requirement that a "dig permit" be obtained. Any construction proposed

within an Operable Unit requires a waiver issued by Headquarters, Air Combat Command,

which includes coordination with the oversight agencies, in order to prevent unauthorized

activities within the Operable Units. These measures are intended to ensure the integrity of the

operation and functionality of the remedy and to prevent unauthorized use of the operable unit

area while remediation is in progress.

In the event of a Base closure action for Ellsworth AFB, there are additional requirements under

CERCLA for site closeout. The Department of Defense (DOD) is required to ensure that "...all

remedial action necessary to protect human health and the environment with respect 'to any

hazardous substance remaining on the property has been taken care of before the date of such

transfer." This would entail a review of the entire program, revisions as necessary,

establishment of appropriate budgets, and administrative steps to ensure the continued integrity

of the remediation process.

The selected remedies also include a Contingency Plan. This Contingency Plan consists of an

ongoing process within the Long Term Monitoring/Long Term Operations (LTM/LTO) program

that will identify any failure of the selected remedy or remedies; establish a budget for necessary

corrective action; obtain funding through the Air Force's project programming system; and

implement the corrective action. For Operable Units that included a landfill cap as a part of the

final selected remedy, quarterly visual inspections of the landfill caps are conducted and repairs

are performed as needed to maintain the integrity of the caps to assure compliance with the

RODs.

Operable Unit 1: ROD Signature Date: August 1995 Interim Remedial Action (IRA), May 1996

Remedial Action (P.A)

The selected alternative at OU-1 provided for removal of contaminants including LNAPL from

soils in the capillary fringe beneath the Fire Training Area, from shallow ground water collected

from wells in the bum-pit area, and from a ground-water collection trench. This has reduced

potential risks to human health. The alternative has prevented the transport of additional

contaminants from the bum-pit area.

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The selected interim remedial action (IRA) for soil and ground-water contamination cleanup at

OU-1 consisted of:

• Soil vapor extraction

• Ground water removal by wells and an existing interceptor trench

• Treatment of soil gas, condensate and ground water

• Surface discharg e of treatment plant effluent

• LTM/LTO contingency plan

Institutional controls and the contingency plan were described at the beginning of this section.

The ground-water plume has been contained by the extraction wells in the Interim Action and

the Final Action. The interim remedial action was found to be consistent with the selected

remedy. Therefore, the final Record of Decision (ROD) has as a final remedy, the expansion of

the interim system of soil vapor extraction (SVE) and ground-water extraction wells. The

Interim Action included SVE wells and combination ground-water extraction/SVE wells to

contain contaminants and begin remediation of soil and ground-water contamination. The Final

Action included additional SVE and ground-water extraction wells to address the contaminants

in soil and ground water.

Status: Remedial Action Report Complete.

Soil vapor and ground-water wells were installed consistent with the final accepted design.

Remedial actions were conducted under the US Army Corp of Engineers Total Environmental

Restoration Contract (TERC - Contract No. DACA45-94-D-0001) awarded on October 22,

1993. The following inspections were conducted:

Pre-Final Construction Inspection for IRA May 30,. 1996

Final Construction Inspection for IRA August 13, 1996

Pre-Final Construction Inspection for RA March 26, 1997

Final Construction Inspection for RA June 6, 1997

OU-1 ground water and soil vapor extraction facilities will require 10 to 20 years of operation

and maintenance (O&M) before the aquifer and soil cleanup levels are reached.

Operable Unit 2: ROD Signature Date: May 1996

The remedial action objectives have provided protection against direct contact with contents of

the landfills, protection against ingestion of contaminated ground-water concentrations

exceeding regulatory or risk-based goals, and minimized the potential for transportation of

contaminants in the soils and ground water beyond the boundaries of the landfills. The selected

altemative for Landfill No. 1 was a presumptive remedy that was a landfill cap and institutional

controls. The major components were:

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• Installing an earth cover over the area of attainment

• Institutional controls

• Realignment and lining of the storm-water channel

• Provide for long-term monitoring

o Provide for long-term maintenance of the remedial actions taken at the operable unit

• LTM/LTO contingency plan

The selected alternative for Landfill No. 6 was institutional controls that restrict future use of the

operable unit and provide long-term monitoring to identify development of future risks

associated with the operable unit.

Institutional controls and the contingency plan were described at the beginning of this section.

The jet fuel ground water contamination south of OU-2 is being addressed by a ground water

extraction and treatment system under the State of South Dakota petroleum release program.

This system will require one to two more years of operation and maintenance (O&M) before the

aquifer cleanup levels are reached.

Status: Remedial Action Report Complete.

An Ordnance and Explosive Waste/Chemical Warfare Materials Archives Search Report has

been completed to determine whether any archival information was available regarding possible

disposal of chemical weapons material (CWM) at Ellsworth AFB, including OU-2. No

information regarding such disposal was found.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No. DACA45-94-D-0001) awarded on

October 22, 1993. The pre-final inspection was conducted on October 9, 1996, and a Final

Inspection of the Landfill cover occurred on May 1, 1997.

Operable Unit 3: ROD Signature Date: June 1996

Human health and environmental risk model results indicated a potential unacceptable risk from

exposure to ground water at the site. Investigation of the existing landfill and its cover found no

ground water plumes. Monitoring for the existence of ground water will ensure the effectiveness

of the presumptive remedy. The remedial action objectives have prevented ingestion and dermal

contact with landfill contents, reduced mobility of potential contaminants in the landfill, and

controlled surface water runoff and erosion of the landfill cover. The selected presumptive

remedy was capping, which included the following major components:

• Eliminate direct exposure to landfill contents by installing an earthen cap

• Reduce the potential percolation of contaminants to the ground water

• Institutional controls

• Provide for long-term monitoring of ground water

• LTM/LTO contingency plan

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Institutional controls and the contingency plan were described at the beginning of this section.

Status: Remedial Action Report Complete.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No. DACA45-94-D-0001) awarded on

October 22, 1993. The pre-final inspection was conducted on February. 20, 1997, and a Final

Inspection of the Landfill cover occurred on May 1, 1997. The need for Ground-water

monitoring will be evaluated after the initial 5-year review (scheduled for May 2000).

Operable Unit 4: ROD Signature Date: August 1995 (IRA) and May 1996 (RA)

The Interim Remedial Alternative (IRA) objectives at OU-4 were to control the movement of

ground water contaminated with volatile organics from the source area and the selected IRA for

OU-4 was ground-water removal and treatment. The major components of this alternative were:

• Ground-water extraction using wells

• Treatment of ground water

• Discharge of treatment plant effluent to surface waters

The Final remedial action objectives for OU-4 prevented dermal contact and ingestion of surface

soils within OU-4; reduced the mobility of potential contaminants in the landfill; and prevented

inhalation, dermal contact, and ingestion of ground water containing contaminants at

concentrations exceeding remediation goals in ground water.

The selected remedial alternative for OU-4 was to install a landfill cover and ground-water

extraction wells for treatment of ground water. The major components of the remedial action

for the landfill cover included:

• Installing an earthen cover over the area of attainment

• Institutional controls to prevent future use of the area for residential use and/or limiting its

use to industrial uses

• Providing for long-term ground-water monitoring to verify the cover maintains operating

functionality

• Providing long-term maintenance of the remedial actions

• LTM/LTO co_*;qgency plan

Institutional controls and the contingency plan were described at the beginning of this section.

The major components of the final remedial action for ground water were:

• Continued operation of the IRA

• Expansion of the IRA system by installation of additional extraction wells and/or trenches

• Treatment of removed ground water

Status: Remedial Action Report Complete.

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Remedial activities were conducted under the US Army Corp of Engineers Total Environmental

Restoration Contract (TERC - Contract No. DACA45-94-D-0001) awarded on October 22,

1993. The following inspections were conducted:

Pre-Final Construction Inspection for IRA May 30, 1996

Final Construction Inspection for IRA August 13, 1996

Pre-Final Construction Inspection (landfill cover) October 9, 1996

Pre-Final Construction Inspection (landfill cover & Ground water) May 1, 1996

Final Construction Inspection (landfill cover & Ground water) June 6, 1996

The OU-4 ground-water extraction facilities will require 10 to 20 years of operation and

maintenance (O&M) by the Air Force before the aquifer cleanup levels are reached.

Operable Unit 5: ROD Signature Date: June 1996

The remedial action objectives were to provide protection against direct contact or ingestion of

the landfill contents, minimize infiltration through the landfill, and control surface water runoff

and erosion of the landfill cover. The selected remedy achieved the objectives through capping,

which included the following major components:

• Placing a soil cover capable of sustaining perennial vegetation over the landfill _ea.

• Institutional controls for the landfill area.

• Long-term ground-water monitoring

• Long-term maintenance of soil cover

• LTM/LTO contingency plan

Institutional controls and the contingency plan were described at the beginning of this section.

Status: Remedial Action Report Complete.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No. DACA45-94-D-0001) awarded on

October 22, 1993. A Pre-Final Inspection was conducted on February 20, 1997 and a Final

Inspection occurred on May 1, 1997. Ground-water monitoring will be re-evaluated after the

initial 5-year review (scheduled for May 2000).

Operable Unit 6: ROD Signature Date: October 1995

The remedial action objectives for the landfill were to prevent dermal contact and ingestion of

surface soils within OU-6 and to reduce the mobility of potential contaminants in the landfill.

The remedial action objectives for sediment were to prevent the ingestion of sedime,nts. The

selected alternative achieved the objectives through the presumptive remedy of capping. The

remedial action included the following major components:

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• Placing a soil cover of at least 24-inches in thickness and capable of sustaining perennial

vegetation, over the landfill area

• Modification of storm-water discharge point and drainage

• Institutional controls

• Long-term ground water, surface water and sediment monitoring

• LTM/LTO contingency plan

Institutional controls and the contingency plan were described at the beginning of this; section.

Status: Remedial Action Report Complete.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No. DACA45-94-D-0001) awarded on

October 22, 1993. The pre-final inspection was conducted on June 10, 1996, and a Final

Inspection of the Landfill cover occurred on July 2, 1996. Ground-water monitoring will be reevaluated after the initial 5-year review (scheduled for May 2000).

Operable Unit 7: ROD Signature Date: June 1996

The remedial action objectives for the site were to reduce the worker inhalation of surface and

subsurface soil contaminants at concentrations exceeding remediation goals and prevent

ingestion of ground water containing contaminants at concentrations exceeding the remediation

goals. The selected remedial alternative has achieved the objectives through a combination of

institutional controls for soil and ground water with additional monitoring. The major

components for soil identified in the ROD were:

• Institutional controls for future land use

• LTM/LTO contingency plan

• The removal action was accepted as the final remedy.

The major components for ground water identified in the ROD were:

• Institutional controls for ground water use

• Implementing a long-term ground-water monitoring and maintenance program

• LTM/LTO contingency plan

Institutional controls and the contingency plan were described at the beginning of this section.

It was found that the removal action was consistent with the final remedy. Excavations were

performed at three locations within the operable unit to determine if low-level radioactive wastes

(LLRW) buried during weapons maintenance, were still present at the site. LLRW was located

at these sites and was removed, transported to a licensed facility out of state, and disposed. The

LLRW consisted of remnants of gloves, swipes, and the boxes in which these materials had been

buried.

Final Draft PCOR 8/18/99 Page 11

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A long-term monitoring plan has been implemented fulfilling the requirements of the ROD. An

Ordnance and Explosive Waste/Chemical Warfare Materials Archives Search Report has been

complete d to determine whether any archival information was available regarding possible

disposal of chemical weapons material (CWM) at Ellsworth AFB. No information regarding

such disposal was found.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No. DACA45-94-D-0001) awarded on

October 22, 1993. The Final Inspection of the Landfill cover occurred on June 6, 1997.

Ground-water monitoring will be re-evaluated after the initial 5-year review (scheduled for May

2000).

Operable Unit 8: ROD Signature Date: June 1996

The remedial action objectives for the Explosive Ordnance Disposal (EOD) area (which

included a Pramitol spill area, burning pit area, burn furnace area, and a detonation site) were to

prevent contaminated surface soil from moving offsite and provide protection against direct

contact or ingestion of surface soils containing contaminants. The remedial action objectives for

the debris burial area were to contain buried and exposed debris, prevent contaminated surface

soil from leaving the site, and provide protection against direct contact or ingestion of soil

containing contaminants.

The selected remedy for both areas has achieved the remedial action objectives through the use

of a vegetative cover and institutional controls, which included the following major components:

• Constructing an earth cover over the EOD and the Debris Burial Areas

• Institutional controls for the EOD and the Debris Burial Areas

• Long-term maintenance of earth cover of the EOD and the Debris Burial Areas

• Long-term sediment sampling at the EOD Area

• LTM/LTO contingency plan

Institutional controls and the contingency plan were described at the beginning of this section.

Status: Remedial Action Report Complete.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No. DACA45-94-D-0001)awarded on

October 22, 1993. The Final Inspection of the Landfill cover occurred on June 6, 1997.

Ground-water monitoring will be re-evaluated after the initial 5-year review (scheduled for May

2ooo).

Operable Unit 9: ROD Signature Date: May 1996

Operable Unit 9 was a "No Action" OU because soil contamination is below MCLs or

acceptable risk-based corrective action limits. There was no need for further action. Groundwater contamination in this area was addressed under Operable Unit 11.

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Operable Unit 10: ROD Signature Date: May 1996

Soil contaminant levels in Operable Unit 10 were found to be below MCLs or acceptable riskbased corrective action levels. There was no need for further action. Ground-water

contamination in this area was addressed under Operable Unit 11.

Operable Unit 11: ROD Signature Date: April 1997

The remedial action objectives for OU-11 were as follows:

• Prevent future human exposure to on-Base ground water with contaminants exceeding State

of South Dakota Ground-Water Quality Standards and Federal MCLs

• Prevent additional ground water, containing contaminants above State of South Dakota

Ground-Water Quality Standards and Federal MCLs, from moving off-Base

• Prevent human exposure to off-Base ground water with contaminants exceeding State of

South Dakota Ground-Water Quality Standards and Federal MCLs

These remedial action objectives were met through the application of the selected remedies

described below.

The major components of the selected remedy for Area 1 were:

• Containment of ground-water contaminants at concentrations above MCLs

• Ground-water treatment and discharge

• Institutional controls and long-term monitoring

• LTM/LTO contingency plan

Institutional controls and the contingency plan were described at the beginning of this section.

The major components of the selected remedy for Area 2 were:

• Ground-water removal and treatment

• Monitored natural attenuation of off-Base ground water

• Alternative water supply to residents affected by contaminated ground-water moving offBase

• Institutional controls and long-term monitoring

• LTM/LTO contingency plan

Status: Remedial Action Report was completed in August 1999.

Punch list items (Attachment A) have been identified which must be addressed to a,;sure the

protectiveness of the selected remedy in accordance with the ROD:

• Modifications to the existing RA systems and Long Term Monitoring plan to maximize

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efficiency of the systems and ensure continual protection to the environment if necessary

based on 5-year reviews

• Additional monitoring wells may be installed in the fall of 1999 to provide more detailed

definition of the capture zones associated with the Base boundary remediation systems.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No.DACA45-94-D-0001) awarded on

October 22, 1993. The following inspections were conducted:

• Pre-Final Inspection December 1997

• FinalInspection January 1998

The OU-11 ground-water extraction facilities will require 20 to 30 years of operation and

maintenance (O&M) before the aquifer cleanup levels are reached.

The jet fuel ground water contamination at the Flightline Refueling Area (FRA) is being

addressed by a ground water extraction and treatment system under the State of SouffLDakota

petroleum release program. This system will require several more years of operation and

maintenance (O&M) before the aquifer cleanup levels are reached.

NOTE: Three property owners have not allowed their residences to be connected to the Air Force provided

alternative water-supply water main as prescribed in the ROD selected remedy for the off-Base contaminant

plume, Operable Unit 1 1. The Air Force has provided water service extensions ending at a curb-stop valve at the

boundary of each of the three residences.

The first property owner retained an attorney but has personally directed placement of the curb-stops for each of

his two homes. Their domestic well is within the buffer zone, an area external to the 5 ppb MCL contaminant line

but within an area of hydraulic influence if well pumping were continued. The TCE concentration in the well is

2.9 ppb and is below the MCL of 5 ppb.

The second property owner has refused service and has not responded to registered mail sent by the Air Force

offering connection to the water main. Their domestic well is within the buffer zone but TCE concentrations are

less than I ppb and is below the MCL of 5 ppb.

The third property owner has accepted water service for its rental property but is reluctant to accept water service

to its personal residence. The owner has been quoted as stating, "171 take TCE in parts per billion over chlorine

in parts per million." The Air Force has provided the owner with product information on a carbon filter system in

case they want to accept water service. Their domestic well is in the TCE plume and the TCE concentration is 1

ppb above the MCL of 5 ppb.

Operable Unit 12: ROD Signature Date: May 1996

The remedial action objectives for OU-12 were to prevent ingestion and dermal contact with

hardfill (building and road demolition rubble) contents, reduce the mobility of potential

contaminants in the hardfill, and control surface water runoff and erosion of the cover.

The selected remedy for OU-12 met the remedial action objectives through capping. The major

components of the altemative were:

• Install an earth cover over the area of attainment at Hardfill No 1

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q

• Institutional controls to prevent future use of the area for residential use and/or limiting its

use to industrial uses

• Developing a long-term monitoring and maintenance plan of the hardfill

• LTM/LTO contingency plan

Status: Remedial Action Report Complete.

Remedial action activities were conducted under the US Army Corp of Engineers Total

Environmental Restoration Contract (TERC - Contract No.DACA45-94-D-0001) awarded on

October 22, 1993. The pre-final inspection was conducted on October 9, 1996, and a Final

Construction Inspection occurred on May 1, 1997. Ground-water monitoring will be reevaluated after the initial 5-year review (scheduled for May 2000).

C. RCRA and other ARAR Actions

Actions at EAFB under the Resource Conservation and Recovery Act (RCRA) and tile

SDDENR Underground Storage Tank (UST) and Leaking Underground Storage Tank (LUST)

program. The UST/LUST actions were concurrent with the CERCLA actions to ensure uniform

cleanup standards. This was done to make sure there was consistency with other Applicable, or

Relevant and Appropriate Standards (ARARs). The following is a list of those ongoing

SDDENR oversight actions as of August 19, 1999:

• Closure of hazardous waste storage facility (March 1999)

• Closure of rubble landfill (scheduled for December 1999)

• Closure of permitted soil farm (August 1999)

• Cleanup of a hazardous waste spill (1995) at Building 88408 under the State of South Dakota

• Ground Water Quality Program

• JP-4 contamination south of OU-2 (2002)

• Flightline Refueling Area (2030)

III. DEMONSTRATION OF CLEANUP ACTIVITY QUALITY ASSURANCE/

QUALITY CONTROL

Activities at the site were consistent with the Records of Decisions (RODs) and the respective

RD/RAs. The remedial design and the remedial action data and operations were carefully

reviewed by EPA CERCLA Program staff, EPA Construction Grants Program, the SDDENR,

EAFB and its prime contractor, the United States Army Corp of Engineers. The reviews were

for compliance with applicable, or relevant and appropriate standards (ARAR_), ,:onceptual

requirements of the ROD, and all applicable QA/QC procedures and protocol.

All procedures and protocol followed for soil and ground-water sampling and analysis were

documented in the respective "RA Work Plans" for each OU and the "Long Term

Operation/Long Term Monitoring Plan and Quality Assurance Project Plan." The ,QA/QC

program used through the RA conformed to EPA and state standards, analytical results are

accurate to the degree needed to assure satisfactory execution of the RA and consistent with the

ARARs addressed in the ROD and the RD plans and specifications.

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_ IV. ACTMTIES AND SCHEDULE FOR SITE COMPLETION

ESTIMATED RESPONSIBLE

TASK COMPLETION ORGANIZATION

Five-Year Review for all OUs May 2000 EAFB

Long Term Monitoring Completion and 2025 EAFB

Clean up Verification

OU- 1, OU-2, OU-4, OU- 11 (Areas 1&2)

Long Term Monitoring Completion and May 2000 EAFB

Clean up Verification

OU-3, OU-5, OU-7, OU-8, OU-12

Final Inspection and Close Out Report 2025 EAFB

SDDENR Actions (UST/LUST)

J-P-4contamination south of OU-2 2002 EAFB

Flightline Refueling Area 2030 EAFB

V. FIVE YEAR REVIEW

Upon completion of these remedies, hazardous substances will remain on site above levels

allowing for unlimited use and unrestricted exposure; therefore, a statutory five-year review will

be conducted on or before May 2000 pursuant to OSWER Directive 9355.7-02, Structure and

Components of Five-Year Reviews, or other applicable guidance.

Approved by: __/__4_1._-- Date _/D/_"_ Max H. Dodson

Assistant Regional Administrator

Office of Ecosystems Protection

and Remediation

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• t "

APPENDIX A

Punch List Items

All OUs

• Modifications to the existing RA systems for Operation and Maintenance. Long Term

Monitoring Plan to assess the efficiency of the systems to provide continual evaluation of

the protection to the environment

Estimated Completion: On-going

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