WRIGHT-PATTERSON AIR FORCE BASE EPA ID: OH7571724312 OU 12 DAYTON, OH 09/29/1999 Record of Decision Groundwater Operable Unit Groundwater Basewide Monitoring Program
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EPA/ROD/R05-99/506 1999 EPA Superfund Record of Decision: WRIGHT-PATTERSON AIR FORCE BASE EPA ID: OH7571724312 OU 12 DAYTON, OH 09/29/1999 Record of Decision Groundwater Operable Unit Groundwater Basewide Monitoring Program Wright-Patterson Air Force Base 88th Air Base Wing Office of Environmental Management RESTORE PROTECT ENHANCE September 8, 1999 RECORD OF DECISION FOR THE GROUNDWATER OPERABLE UNIT AT WRIGHT-PATTERSON AIR FORCE BASE Wright-Patterson Air Force Base 88th Air Base Wing Office of Environmental Management Wright-Patterson Air Force Base, Ohio September 8, 1999 Table of Contents I THE DECLARATION 1.0 Site Name and Location .................................................. I-1 2.0 Statement of Basis and Purpose........................................... I-1 3.0 Assessment of the Site................................................... I-1 4.0 Description of the Selected Remedy....................................... I-1 5.0 Data Certification Checklist ............................................ I-2 II DECISION SUMMARY 1.0 Site Name, Location, and Description.................................... II-1 1.1 Site Location and Description ...................................... II-1 1.2 Geologic and Hydrogeologic Description.............................. II-1 2.0 Site History and Enforcement Activities ................................ II-2 3.0 Highlights of Community Participation................................... II-3 4.0 Scope and Role of Response Action Within Site Strategy.................. II-3 5.0 Summary of Site Characteristics ........................................ II-4 6.0 Summary of Site Risks................................................... II-5 6.1 Groundwater Human Health Risk....................................... II-5 6.1.1 Current Conditions Risk Assessment (CCRA).................. II-6 6.1.2 Future Conditions Risk Assessment (FCRA)................... II-6 6.2 Ecological Risk Evaluation of Surface Water and Sediment ........... II-7 7.0 Determination of Groundwater Remediation Goals and Removal Action Objectives ............................................................. II-7 8.0 Description of Alternatives............................................. II-8 8.1 Further Action Area A............................................... II-8 8.1.1 General Geologic and Hydrogeologic Characteristics ........ II-9 8.1.2 Contaminant Characteristics ............................... II-9 8.2 Further Action Area B .............................................. II-12 8.2.1 General Geologic and Hydrogeologic Characteristics ........ II-12 8.2.2 Contaminant Characteristics ............................... II-12 8.3 Remainder of GWOU................................................... II-13 9.0 Summary of the Comparative Analysis of Alternatives..................... II-14 9.1 Further Action Area A............................................... II-16 9.2 Further Action Area B .............................................. II-18 9.3 Remainder of GWOU................................................... II-19 10.0 The Selected Remedy..................................................... II-21 10.1 Remedy Description for FAA-A....................................... II-22 10.2 Remedy Description for FAA-B....................................... II-23 10.3 Remedy Description for the Remainder of the GWOU .................. II-23 11.0 Statutory Determination ................................................ II-23 11.1 Protection of Human Health and the Environment .................... II-23 11.2 Compliance with Applicable or Relevant and Appropriate Requirements II-24 11.3 Cost-Effectiveness................................................. II-24 11.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the Maximum Extent Practicable..................... II-24 12.0 Documentation of No Significant Change.................................. II-25 III RESPONSIVENESS SUMMARY Index of Documents in the Administrative Record Pertinent to the Groundwater Operable Unit List of Tables Table 1 – Remediation Goals for COPCs Table 2 – List of ARARs for the GWOU Table 3 – Estimated Cost of Remedy for GWOU List of Figures Figure 1 – Area Location Map Figure 2 – Site Location Map Figure 3 – Current Organics Cancer Risk Contour Map Figure 4 – Organics 30 Year Cancer Risk Contour Map Figure 5 – Location of Further Action Area A Figure 6 – PCE Concentration in Groundwater – Further Action Area A Figure 7 – TCE Concentration in Groundwater – Further Action Area A Figure 8 – TCE in Selected Wells as a Function of Time Figure 9 – Vinyl Chloride Concentration in Groundwater – Further Action Area B Figure 10 – Groundwater Treatment System Process Flow Diagram ABBREVIATIONS AOC Administrative Orders on Consent ARAR Applicable or Relevant and Appropriate Requirements AFMC Air Force Materiel Command ATSDR Agency for Toxic Substances and Disease Registry BMP Basewide Monitoring Program CCRA Current Conditions Human Health Risk Assessment CERCLA Comprehensive Environmental Response, Compensation, and Liability Act COPC Contaminant of Potential Concern EcoRA Ecological Risk Assessment EE/CA Engineering Evaluation/ Cost Analysis FAA Further Action Area FS Feasibility Study FCRA Future Conditions Human Health Risk Assessment GWOU Groundwater Operable Unit gpm gallons per minute HI Hazard Index HQ Hazard Quotient IRP Installation Restoration Program MCL Maximum Contaminant Level NCP National Contingency Plan NPDES National Pollutant Discharge Elimination System NPL National Priority List OAC Ohio Administrative Code OEPA Ohio Environmental Protection Agency O&M Operation and Maintenance OU Operable Unit PAH Polycyclic Aromatic Hydrocarbon PCE Perchloroethylene or Tetrachloroethylene PELP Potential Exposure Location Point PW Present Worth RA Remedial Action RD Remedial Design RAO Removal Action Objective RI Remedial Investigation ROD Record of Decision SARA Superfund Amendments and Reauthorization Act SDWA Safe Drinking Water Act SI Site Investigation TCE Trichloroethylene USEPA United States Environmental Protection Agency USGS United States Geological Survey UV/OX Ultraviolet/ Oxidation VOC Volatile Organic Compound WPAFB Wright-Patterson Air Force Base I THE DECLARATION 1.0 Site Name and Location This Record of Decision (ROD) addresses the findings of investigations at Installation Restoration Program (IRP) Sites OT069 and OT070 (also known as the Groundwater Operable Unit [GWOU]) at Wright-Patterson Air Force Base (WPAFB). WPAFB is located in Greene and Montgomery Counties, Ohio. 2.0 Statement of Basis and Purpose This decision document presents the rationale for the selected remedial alternative for the GWOU at WPAFB. The selection process was conducted in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act (SARA), and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The United States Air Force (USAF) is the lead agency for WPAFB with the U. S. Environmental Protection Agency (USEPA) and the Ohio EPA (OEPA) as support agencies. The lead agency, USAF, along with the support agencies, USEPA and OEPA, recommend the selected alternative for the GWOU. This decision is based on the Administrative Record for WPAFB. 3.0 Assessment of the Site The USAF has determined that actual or threatened releases of hazardous substances from this site, if not addressed by implementing the response action selected in this ROD, may present an imminent and substantial endangerment to public health, welfare, or the environment. These risks will be addressed by implementing the recommendations presented in this ROD. 4.0 Description of the Selected Remedy This ROD presents the selected remedy for the GWOU at WPAFB. This ROD is the sixth and final ROD for sites at WPAFB. Previous RODs have addressed sources of contamination at identified Operable Units (OUs) and individual sites within those OUs. The selected remedy addresses the principal threats posed by groundwater at WPAFB by treating the most highly contaminated areas of groundwater and those areas of contaminated groundwater most likely to migrate off-site. The selected remedy for the GWOU at WPAFB is: • Continue current groundwater extraction, treatment and discharge at the WPAFB property boundary in OU5 and continue long- term monitoring in this area. This area has been termed “Further Action Area A”. • In-situ chemical oxidation in the area near Spill Site 11 and monitoring. This area has been termed “Further Action Area B”. • Long-term monitoring for the remainder of the GWOU. Those areas to be monitored are: - Areas that exceed Maximum Contaminant Levels (MCLs) for organic contaminants of potential concern (COPCs), but do not exceed the target risk range of 1x10-4 to 1x10-6. - Areas that exceed a cumulative cancer risk of 1x10-4 or a Hazard Index of 1 for organic COPCs, but do not exceed MCLs. - Areas exceeding remediation goals (MCLs or background) for inorganic COPCs. - Areas with existing remedies in place (OU1 and OU2). I-1 • Access restrictions to limit access to groundwater. The bulk of the GWOU is located within an active military installation with limited access. This access restriction is applicable to the installation of private wells and new public water supply well fields. Public water supply wells will require approval from the State of Ohio prior to installation. WPAFB, as an active military installation, will control the installation of private wells.