EPA/ROD/R04-02/038 2002 EPA Superfund Record of Decision: REASOR CHEMICAL COMPANY EPA ID: NCD986187094 OU 01 CASTLE HAYNE, NC 09/26/2002 RECORD OF DECISION SUMMARY OF REMEDIAL ALTERNATIVE SELECTION REASOR CHEMICAL COMPANY SITE CASTLE HAYNE, NEW HANOVER COUNTY, NORTH CAROLINA PREPARED BY: U.S. ENVIRONMENTAL PROTECTION AGENCY REGION 4 ATLANTA, GEORGIA SEPTEMBER 2002 Record of Decision Page i Reasor Chemical Company Site September 2002 Table of Contents LIST OF ACRONYMS and ABBREVIATIONS .................................... vi PART 1: THE DECLARATION..................................................1 1.1 Site Name and Location...................................................1 1.2 Statement of Basis and Purpose.............................................1 1.3 Assessment of Site.......................................................1 1.4 Description of Selected Remedy............................................1 1.5 Statutory Determinations..................................................2 1.6 Data Certification Checklist................................................2 1.7 Authorizing Signatures ...................................................3 PART 2: THE DECISION SUMMARY............................................4 2.1 Site Name, Location, and Brief Description ...................................4 2.2 Site History and Enforcement Activities ......................................4 2.2.1 Activities that lead to current problem ..................................4 2.2.2 Previous Investigations .............................................6 2.2.2.1 Preliminary Environmental/Liability Assessment, 1989 ..............6 2.2.2.2 Preliminary Assessment, 1991 ..................................7 2.2.2.3 Emergency Response and Removal Branch Site Investigation, 1991 ....7 2.2.2.4 Site Investigation, 1995 .......................................7 2.2.2.5 Remedial Investigation, 1996-1999 ..............................8 2.2.2.6 Ecological Risk Assessment, 1999-2002 ..........................8 2.2.3 Enforcement Activities .............................................9 2.3 Community Participation..................................................9 2.4 Scope and Role of Operable Unit or Response Action ...........................9 2.5 Site Characteristics......................................................10 2.5.1 Conceptual Site Model .............................................10 2.5.2 Site Overview ....................................................11 2.5.3 Surface and Subsurface Features .....................................11 2.5.4 Sampling Strategy ................................................12 2.5.5 Known and/or Suspected Sources of Contamination ......................12 2.5.6 Types of Contamination and Affected Media ...........................12 2.5.6.1 Surface Soil ...............................................12 2.5.6.2 Subsurface Soil ............................................15 2.5.6.3 Sediment .................................................16 2.5.6.4 Surface Water ..............................................17 2.5.6.5 Groundwater ..............................................20 2.5.6.5.1 Temporary Wells ................................20 2.5.6.5.2 Production Wells ................................22 2.5.6.5.3 Permanent Monitor Wells .........................23 2.5.6.5.4 Residential and Community Wells ..................24 2.5.6.6 Liquid Tar Sample ..........................................25 2.5.7 Location of Contamination and Migration ..............................25 2.5.7.1 Lateral and Vertical Extent of Contamination .....................25 2.5.7.2 Current and Potential Future Surface and Subsurface Routes of Human or Environmental Exposure.....................................28 2.5.7.3 Likelihood for Migration .....................................28 Record of Decision Page ii Reasor Chemical Company Site September 2002 2.5.8 Groundwater Contamination ........................................28 2.6 Current and Potential Future Land and Water Uses.............................29 2.6.1 Land Uses .......................................................29 2.6.2 Groundwater Uses ................................................29 2.7 Summary of Site Risks...................................................29 2.7.1 Summary of Human Health Risk Assessment ...........................29 2.7.1.1 Identification of Chemicals of Concern ..........................29 2.7.1.2 Exposure Assessment ........................................31 2.7.1.3 Toxicity Assessment ........................................31 2.7.1.4 Risk Characterization ........................................33 2.7.1.5 Uncertainties ..............................................37 2.7.2 Summary of Ecological Risk Assessment ..............................39 2.7.2.1 Identification of Chemicals of Concern ..........................39 2.7.2.2 Exposure Assessment ........................................42 2.7.2.3 Ecological Effects Assessment ................................47 2.7.2.4 Ecological Risk Characterization ...............................48 2.8 Remedial Action Objectives ..............................................52 2.9 Description of Alternatives ...............................................53 2.9.1 Description of Remedy Components ..................................53 2.9.1.1 Soil and Sediment Alternatives ................................53 2.9.1.2 Groundwater Alternatives ....................................55 2.9.1.3 Surface water Alternatives ....................................57 2.9.2 Common Elements and Distinguishing Features of Each Alternative .........59 2.9.3 Expected Outcomes of Each Alternative ...............................60 2.9.3.1 Soil and Sediment Alternatives ................................60 2.9.3.2 Groundwater Alternatives ....................................60 2.9.3.3 Surface Water Alternatives ...................................61 2.10 Comparative Analysis of Alternatives .......................................61 2.10.1 Overall Protection of Human Health and the Environment .................61 2.10.1.1 Soil and Sediment Alternatives ..........................62 2.10.1.2 Groundwater Alternatives ..............................62 2.10.1.3 Surface Water Alternatives .............................62 2.10.2 Compliance with Applicable or Relevant and Appropriate Requirements .....63 2.10.2.1 Soil and Sediment Alternatives ..........................64 2.10.2.2 Groundwater Alternatives ..............................64 2.10.2.3 Surface Water Alternatives .............................65 2.10.3 Long-Term Effectiveness and Permanence .............................66 2.10.3.1 Soil and Sediment Alternatives ..........................66 2.10.3.2 Groundwater Alternatives ..............................67 2.10.3.3 Surface Water Alternatives .............................67 2.10.4 Reduction of Toxicity, Mobility, or Volume Through Treatment ............68 2.10.4.1 Soil and Sediment Alternatives ..........................68 2.10.4.2 Groundwater Alternatives ..............................68 2.10.4.3 Surface Water Alternatives .............................68 2.10.5 Short-Term Effectiveness ..........................................68 2.10.5.1 Soil and Sediment Alternatives ..........................68 2.10.5.2 Groundwater Alternatives ..............................69 Record of Decision Page iii Reasor Chemical Company Site September 2002 2.10.5.3 Surface Water Alternatives .............................69 2.10.6 Implementability .................................................70 2.10.6.1 Soil and Sediment Alternatives ..........................70 2.10.6.2 Groundwater Alternatives ..............................70 2.10.6.3 Surface Water Alternatives .............................71 2.10.7 Cost ...........................................................71 2.10.7.1 Soil and Sediment Alternatives ..........................71 2.10.7.2 Groundwater Alternatives ..............................72 2.10.7.3 Surface Water Alternatives .............................72 2.10.8 State/Support Agency Acceptance ....................................72 2.10.9 Community Acceptance ............................................73 2.11 Principal Threat Wastes ..................................................78 2.12 Selected Remedy .......................................................78 2.12.1 Summary of the Rationale for the Selected Remedy ......................78 2.12.1.1 Soil and Sediment ....................................78 2.12.1.2 Groundwater ........................................79 2.12.1.3 Surface Water ........................................79 2.12.2 Description of the Selected Remedy ..................................79 2.12.2.1 Step 1 - Groundwater - Institutional Controls with Monitoring . 80 2.12.2.2 Step 2 - Surface Water - Off Site Treatment/Disposal .........80 2.12.2.3 Step 3- Soil Sediment - Excavation and Off-site Disposal .....81 2.12.2.4 Step 4 - Groundwater (Contingent Remedy) ................82 2.12.3 Summary of the Estimated Remedy Costs ..............................85 2.12.4 Expected Outcomes of the Selected Remedy ............................88 2.12.4.1 Available Land Use after Cleanup ........................88 2.12.4.2 Final Clean-up Levels .................................89 2.12.4.3 Anticipated Environmental and Ecological Benefits ..........90 2.13 Statutory Determinations .................................................90 2.13.1 Protection of Human Health and the Environment .......................90 2.13.2 Compliance with Applicable