FIN A L S UPERFUND PRELIM I NARY C LO S EOUT RE PORT 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 O F SITE CONDITI O NS A. Background Ellsworth AFB is located 12 mi les east of Rap i d City, South Dakota, and a dj a cent 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 m ai n Air B a se covers 4,858 acres within Meade a nd Peunington Counties. The B a se 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 i d enti fi ed at EAF B

. I n ad d ition, 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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## 4235 001Operable 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 c o nsisted of former Landfill N o . 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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## 4235 002Operable Unit 4 OU- 4 , which includes Landfill No. 3, is a 40 -acre site located south of the aircraft control t o wer in the sou thwes t ern portion of the Ba s e. S o il at OU-4 c o ntained elevat ed VOCs, SVOCs, and pes ticides wi thin the EAFB boundary. Gr o und wate r c o ntained chl o rinated VOCs, SVOCs, and pesticides. C o ntaminated gro und water with i n this OU m o ved fr o m the landfill, l o cated within the o riginal Base b o undaries, t o an adjacent area within the OU, wh i ch is n o w o wned by the Air F o rce. Operable Uni t 5
OU-5 included the area surrounding and including Landfill No. 4 , a ten-acre si t e near the northern perimeter of EAFB.
P o lynuclear aromatic hy d rocarbons (PAHs) at estimated values below the sample quantitation limit (48 _g / kg t o 250 /a g / kg) and JP-4 jet fuel, in o ne surface s o il sample (SB 9 305 0 2) at 1 9 0 mg / kg, were rep o rted in s oi l samples c o llected f ro m OU-5. Jet fuel was als o rep o rteci at a c o ncentrati o n o f 1 00 _g / L in o ne gr o und-water sample c o llected during the investigati o n. Operable Unit 6 OU-6 consi st ed o f Landfill N o . 5, which is approximat ely seven acres in size and is located near the s outhe r n end of EAFB. Polynuclear aromatic hydrocarbons an d pesticides were reported in s o il samples c o llec t ed 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 Radi o ac tive Was t e Bu r ial site l o cated in the Weapons St o rage Area (WSA) at th e north e rn end of the Bas e . The WSA cove rs app r oximat e l y 65 ac r e s and i s cu rre ntl y ac tive. Th e s i te con t ain e d five unde r g r ound tanks , which we r e d es igned t o hold equipm e n t washdown wat e r . The re co r d search fo r the OU- 7 inve stigation found no evidence that th ese t anks we r e e ve r u se d fo r th e pu rpose of ho l ding wa s hdown wat e r con t aining radioac tive mate r ials. The t anks we r e emp tied of wate r in 1 993. I n o r de r t o s ample the s oil s surrounding th e tanks, the t anks w ere re moved and di s po s ed. Scatt ered detections o f VOCs were repo rted in su r face soil samples at OU-7; concentrati o ns w ere b e low 1 0.6 ri s k bas e d concent r ations fo r Human Health Ri s ks. Radionuclides we r e de ter mined t o be p r esen t within the no r mal backg r ound range due t o natu r al variations in s oi l ty pes and geological charac t eris tics.

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## 4235 003Operable 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 O U-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 chlorinatedVOCs 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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## 4235 004Volatile 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). T he contaminant of concern associated with Area 2 is T CE 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 appro z dmately 14 acres in size. T his 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. T he investigation showed the presence of VOCs, SV O Cs, 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. T he 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. Re m e dial Con s truction Activiti e s 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 R A 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 c o mpleted 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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## 4235 005The 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 haz ardous 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 als o include a Contingency Plan. This Contingency Plan c o nsists 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 f o r necessary corrective action; obtain funding through the Air Force's project programming system; and implement the c o rrective acti o n. 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 (IR A ), 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. T he alternative has prevented the transport of additional contaminants from the bum-pit area.

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## .............................. 4235 006The 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 T otal 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 operati o n 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 maj o r comp o nents were:

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## ....... 4235 007• 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 c o ntr o ls and the c o ntingency plan were described at the beginning o f this secti o n. 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 Environment a l Restor a tion Contr a ct (TERC - Contract No. DACA45-94-D-0001) awarded on October 22, 1993. The pre-final inspection was conducted on October 9, 1996, a nd 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. T he remedial action objectives have prevented ingestion and dermal c o ntact 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 • L T M

/ LTO contingency plan

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## ..................... 4235 008Institutional 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 an d 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 f u ture 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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## ....... 4235 009Remedial activities were conducted under the US Army Corp of Engineers To t al 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 o peration 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 o bjectives were t o 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 Uni t 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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## 4235 010• 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 T o tal 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 FinalInspection 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 t o reduce the w o rker inhalation o f 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 c o mp o nents for gr o und water identified in the ROD were: • Institutional controls for ground water use • Implementing a long-term ground-water monitoring and maintenance program • L T M

/ LT O 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.

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## 4235 011A 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 remedi a l 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 fo r 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 E O D 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 contr o ls 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 oracceptable 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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## ...... 4235 012Operable Unit 10: ROD Signature Date: May 1996Soil 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 Sta tu s: 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 t o the existing RA systems and Long Term M o nitoring plan to maximize

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## • 4235 013efficiency 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 pro vided alternative water

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

- Base conta m inant 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 place m ent 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 proper ty but is reluctant to accept water se rv ice to its personal residence

. The owner has been quoted as stating, " 1 7 1 take TCE in parts per billion o v er chlorine in parts per million ." Th e Air Force has provided the owner with product information on a carbon filter syste m in case they want to accept water se rv ice

. 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 o f 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 Final PCOR 9 /10 / 99 Page 14


## 4235 014q • 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 FinalConstruction Inspection occurred on May 1, 1997. Ground-water monitoring will be reevaluated after the initial 5-year review (scheduled for May 2000). C. R CRA and oth e r ARA R Actions Acti o ns 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 / LUS T 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 haz ardous waste storage facility (March 1999) • Closure of rubble landfill (scheduled for December 1999) • Closure of permitted soil farm (August 1999) • Cleanup of a haz ardous 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 "R A 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.

Final PCOR 9 /10

/ 99 Page 15


## 4235 015_ IV. ACTMTIES AND SCHEDULE FOR SITE COMPLETION ESTIMATED RESPO N SIBLE TASK COMPLETION ORG AN IZATION

Five-Year Review for all OUs May 2000 EAFB
Lo n g Term Monitoring Completion and 2 0 25 EAFB Clean up Verificatio n OU- 1, O U-2, O U-4, OU- 11 (Areas 1&2) Long Term Monitoring Completion and May 2000 EAFB Clea n up Verification O U-3, O U-5, O U-7, OU-8, O U-12 Final Inspection and Close Out Report 2025 E A FB SDDENR Actions (UST / LUST) J-P-4co n taminatio n s outh of OU-2 2002 EAF B Flightline Refueling Area 2030 EAFB

V. F IVE YE A R REVI E W Upo n comp letion of these r emedies, hazar d ous 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.

Approv ed b y: __ /__4

_ 1._

-- Date

_ /

D / _"_ Max H . Do ds o n Assistant Regional Administrator O ffi ce of Ecosystems Protection

and Remediation

F inal PC OR9 / 10

/ 99 P ag e 1 6



## 4235 016• t " APPENDIX A
Punch List Items
All O U s

• M odification s to th e e x i s ting RA s y s tem s fo r Oper a tion and M aintenance

. Long T erm Monito ring Plan to a ss e ss th e efficiency o f th e s y s tem s t o p r ovide continual evaluation of th e protection to th e environment Estimated Completion: On - goin g

Fin a l PCO R 9 /10

/ 99 Pag e 1 7



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