OD-1 •anora a< Oaolatoa ll«l«an Alx roroa Baa* . Lb Eielson Air Force Base Operable Unit 1 Declaration of the Record of Decision Site Name and Location Operable Unit I Eielson Air Force Base, Alaska statement of Basis and Purpose This decision dociunent presents the selected remedial actions and no action decisions for Operable Unit i (OUl) at Eielson Air Force Base, Alaska, chosen in accordanc?: with the Comprehensive Environmental Response, Compensation, mid Liability Act (CERCLA), as amended by the Superfitnd Amendments ami Reaiithonzation Act (SARA), the May 1591 Federal Facility Agreement Under CERCLA Section 120 entered into by the U.S. Air Force, the U.S. Environmental Protection Agency, and. - the State of Alaska, and to the extent practicable, the National Contingency Plan. This decision is based on the administrative record file for this operable unit. The State of Alaska concurs with the selected remedies and the no action decisions. Assessment of the Sites in Operable Unit 1 OU1 consists of eight source areas that have been combined because of commonalty in contamination that is mainly caused by leaks and spUls of fiiels. The QUI source areas are • ST20 E-7, E-8, and E-9 Complexes (RefueUng Loop) • ST48 Power Plant Area • ST49 Alert Hanger • SSSO Blair I^es Vehicle Maintenance • SS51 Blair Lakes Ditch • SS52 Blair Lakes Diesel SpiU • SS53 Blair Lakes Fuel SpUl • DP54 Blair Lakes Dnun Disposal Site Three ofthe source areas (ST49, SS53, and DPS4) wUl receive no further remedial action because they present Uttle risk to human health and the environment. The no further action detemiination was made based on a remedial investigation/feasibUity study and a basewide draft ecological assessment. Although 1 USEPA SF AR 1. 1042361 O0-1 •aoord o£ Daolalan Blalaon Jklx raroa Baa* no fiirther action is required, the groundwater at ST49 wiU continue to be monitored as part ofthe Sitewide Program to confirm the results of die remedial investigation. ST20 (E-7, E-8, and E-9), ST48, SS50, SS51, and SS52 wUl be remediated. Actual or threatened releases and e^qiosure of people to hazardous substances from ST20 (E-7, E-8, and E-9), ST48, SS50, SS51, and SS52 within OUl, if not addressed by implementing the response action selected in this record of decision, may present an imminent and substantial endangerment to public health, welfere, or the environment. Description of the Selected Remedy A feasibihty sttidy was conducted for ST20 (E-7, E-8, and E-9), ST48, ST49, SS50, SS51, and SS52. Sites within ST20 were separated into E-7, E-8, and E-9 based on their distance and source areas SS50, SS51, and SS53 were combined into one site (Blair Lakes) because of dieir proximity. Three remedial alternatives were considered in detaU for each site. They are: Altemative 1 No action Alternative 2 In Situ Altemative Alternatives Removal Altemative Alternative 2 is the selected remedy for aU fif die source areas for which treatment is recommended (E-7, E-8, E-9, ST48, SS50, SS51 and SS52). It addresses die threats posed to human health and die environment by reducing the source of groundwater contamination at each source area. This remedy is intended to achieve groimdwater cleanup through source removal. The major components ofthe selected remedy include the foUowing: • Continue to operate the passive skimming system at SSS1. • InstaU passive skimming systems to ronove fuel floating atop the groundwater if the product is sufficiendy mobUe to be recoverable. • InstaU a bioventing/soil vapor extraction (SVE) system to remediate soil contamination that poses a direat to groundwater dirough leaching at ST20 (E-8 Conq)lex), SSSO, SS51, and SS52. This system may include air injection within the upper part ofthe groundwater table and the smear zone to volatilize and promote bioremediation ofthe contaminants. This entire system is also anticipated to reduce fuel floating atop the groundwater. The eflect of a bioventing system on the permafi-ost at Blair Lakes wUl be evaluated prior to implementation. • Expand the bioventing/SVE systems currentiy operating under the interim remedial action (OU 1B) at ST20 (E-7 and E-9 Complexes) and ST48 to remediate soU contamination that poses a threat to groimdwater through leaching. This system expansion may include air injection within the upper part ofthe groundwater table and the smear zone to volatilize and pranote biomnediation ofthe contamin­ ants. This entire system is also anticipated to reduce fuel floating atop the groundwater. OO-l a*oaxA ot Daelalan • laia«w> JLlx roxoa U*M» • Monitor groundwater at ST20 (E-7, E-8, and E-9 Complexes), ST48, SS50, SS51, and SS52, including increased monitoring (e.g., increased frequency, additional monitoring wells) near base water supply wells, to evaluate contaminant fate and transport until remediation levels are achieved. • Notify the regulatory agencies of proposed dewatering activities, and evaluate their potential for impacting areas of groundwater contamination. • Implement institutional controls to prevent exposure to contaminated groundwater. In the event of base closure, any remaining contaminated source areas will be addressed in accordance with CERCLA Section 120. • Perform supplemental soU and groundwater sampling in the vicinity of weU 50M05 (Blair Lakes) to confirm that no significant contamination remains. Altemative 2 reduces risk substantiaUy through treatment ofthe principal sources of groundwater contamination—fuels on top ofthe groundwater and sod contamination. Gtoundvrater monitoring and institutional controls to restrict the use of groundwater wiU continue in the source areas. Institutional land use controls wiU be designed to prevent exposiu^ to contaminated groundwater and will involve prohibiting the installation and use of any weU for drinking water that could extract contaminated groimdwater or affect the movement of contaminated groundwater. Site maps wUl be developed showing areas currentiy and potentiaUy in^J^cted by groundw^er contaminants. This information can be referenced during base permitting procedures. To ensure long-term integrity ofthe above land use controls, the Air Force wUl ensure that, to the extent that groimdwater contamination remains above unacceptable levels, deed restrictions or equivalent safeguards will be implemented in the event that property containing such contamination is transferred by the Air Force. statutory Determination The selected remedies protect human health and the environment, comply with federal and state requirements that are legaUy appUcable or relevant and appropriate to the remedial actions, and are cost efiective. The remedies use permanent solutions and alternative treatment (or resource recovery) technologies to the maximum extent practicable and satisfy the stamtory preference for remedies that enqjloy treatment that reduces toxicity, mobiUty, or volume as a principal element. Because this remedy wiU result in hazardous substances remaiining on-site above health-based levels, reviews wiU be conducted at ST20 (E-7, E-8, and E-9 Complexes), ST48, SSSO, SSS 1, and SS52 widiin S years after commencement of remedial action to ensure that the remedy continues to provide adequate protection of human healdi and the environment. m SEP-27-1994 14:50 PROM ftF/CEUR TO 919073773357 P. 02 OU-1 Ktcard afDedsioii DdsoB Air Forae Base Eielson Air Force Base - Record of Decision Signature and Support Agency Acceptance of the Remedy for OUl -^ "^k^ U / ^! /-^/^ (T^ - 1'' lOMAS W. L. McCALL. Jr. Date Deputy Assistant Secretary of the U.S. Air Force (Enviromnent, Safety, and Occupational Health) IV Ol'-l Kecord of DecisioD EieKnn .\ir Force lia->* Eielson Air Force Base - Record of Decision Signature and Support Agency Acceptance of the Remedy for GUI ^^;i // ^/^ 9/^7/9^ 7ILLIAM D. McGEE Date Regional Administrator Northem Regional Office Alaska Department of Environmental Conservation OU-1 Record of Decision Eielson Air Force Base Eielson Air Force Base - Record of Decision Signature and Support Agency Acceptance of the Remedy for QUI AyQHUCK CLARKE Date ( Regidnal Administrator Region 10 U.S. Environmental Protection Agency VI OO-l lannril o£ Oaolalon Mlaiann JUJT raroa Baa* Contents Declaration ofthe Record of Decision i Signature and Support Agency Acceptance ofthe Remedy iv 1.0 Site Name, Location, and Description l.l 2.0 Site History and Enforcement Activities 2.1 3.0 Highlights of Community Participation 3.1 4.0 Scope and Role of Operable Unit 4.1 S.O' Summary of Site Characteristics S.l 5.1 Source Area ST20 RefiieUng Loop (Er7, E-8, and E-9 Complexes) S.8 5.1.1 SoU Contamination at die E-7 Con^jlex 5.10 5.1.2 Groundwater Contamination at the E-7 Complex ".. 5.10? 5.1.3 Floating Fuel at the E-7 Complex 5.10 5.1.4 Source Area Hydrology at the E-7 Complex 5.10 5.1.5 SoU Contamination at the E-8 Complex 5.12 5.1.6 Groundwater Contamination at the E-8 Complex 5.12 5.1.7 Floating Fuel at die E-8 Complex 5.12 5.1.8 Source Area Hydrology at the E-8 Complex 5.14 5.1.9 SoU Contamination at the E-9 Conq)lejc 5.14 5,110 Groundwater Contamination at tiie E-9 Complex 5.14 5.1.11 Floating Fuel at the E-9 Complex 5.14 5.1.12 Source Area Hydrology at the E-9 Complex 5.17 5.2 Source Area ST48 Power Plant Area i 5.17 5.2.1 SoU Contamination at ST48 5.19 5.2.2 Groundwater Contamination at ST48 5.19 5.2.3 Floating Fuel at ST48 5.21 5.2.4 Source Area Hydrology at ST48 5.21 5.3 Source Area ST49 Alert Hanger 5.22 5.3.1 SoU Contamination at ST49 5.22 5.3.2 Groundwater Contamination at ST49 5.24 5.3.3 Floating Fuel Contamination at ST49 5.24 5.3.4 Source Area Hydrology at ST49 5.25 vu OO-l Baonrd at Daelalaa llalaoo Alx Voroa Baa* 5.4 Blair Lakes Target FacUity (Source Areas SSSO, SS51, SSS2, SS53, and DP54) 5.25 5.4.1 SoU Contamination for Blair Lakes Target FacUity 5.26 5.4.2 Groundwater Contamination for Blair Lakes Target FacUity 5.28 5.4.3 Floating Product at Blair Lakes Target FacUity.