Record of Decision (Rods)
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RECORD OF DECISION SUMMARY OF REMEDIAL ALTERNATIVE SELECTION SMALLEY-PIPER SUPERFUND SITE COLLIERVILLE, SHELBY COUNTY, TENNESSEE PREPARED BY: U.S. ENVIRONMENTAL PROTECTION AGENCY REGION 4 ATLANTA, GEORGIA SEPTEMBER 2008 10534610 RECORD OF DECISION Smalley-Piper Superfund Site THE DECLARATION Site Name and Location This Record of Decision (ROD) is for the Smalley-Piper Superfund Site located at 719 Piper Street in Collierville, Shelby County, Termessee. The U.S. Environmental Protection Agency (EPA) Site Identification Number is TNN000407378. Statement of Basis and Purpose This decision document presents the Selected Remedy for the Smalley-Piper Superfund Site located in Collierville, Shelby County, Tennessee, which was chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA), and, to the extent practicable, the National Contingency Plan (NCP). This decision is based on the Administrative Record for the Site. This decision represents the final remedy selected for the Site and following completion ofthe remedial action, the Site will be ready for reuse. The State of Tennessee, as represented by the Tennessee Department of Environment and Conservation (TDEC), has been the support agency during the remedial investigation/ feasibility study (RI/FS) process. In accordance with 40 Code of Federal Regulations (CFR) Section 300.430 et. seq., as the support agency, TDEC has provided input during the process, actively participated in the decision-making process, and concurred with the selected remedy. Assessment of the Site Actual or threatened releases ofhazardous substances fi-om 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. Description of the Selected Remedy This Selected Remedy is excavation and ex-situ stabilization/solidification of contaminated source area soil, disposal of treated soil to a non-hazardous waste disposal facility, and long- term ground water recovery and treatment for total chromium, hexavalent chromium, antimony, and iron. Specific elements ofthe Selected Remedy are: 1. Excavation of contaminated soil 2. Chemical stabilization and solidification of contaminated soil 3. Off-site disposal of stabilized soil 4. Extraction of contaminated ground water 5. Ex-situ treatment of contaminated ground water 6. Disposal of treated water 7. In-situ soil flushing 8. Implementationof institutional controls The main activities associated with these remedy components are: (1) excavating 144,000 cubic feet of contaminated soil; (2) chemically stabilizing and solidifying the excavated soil into a non-hazardous solid matrix; (3) transporting the stabilized/solidified soil to a local off- site non-hazardous waste facility for disposal; (4) constmcting and operating ground water extraction wells to remove contaminated ground water from various parts ofthe contaminated plume; (5a) constmction and operation of a source area ground water treatment facility using conventional chemical reduction and precipitation; (5b) dewatering, solidifying and disposing (at an off-site hazardous waste facility) the chemical treatment residue; (5c) constmction and operation of up to two additional water extraction and treatment systems in the northwest and southwest portions ofthe plume using ion-exchange resin technology; (6) water extracted fi-om the source area will be reinjected into the Memphis aquifer after treatment. Water extracted from any additional locations beyond the source area will either be made available to the Town of Collierville as potable water or reinjected into the Memphis aquifer, depending on the Town's potable water requirements; (7a) flushing the subsurface soil below the excavation depth with treated ground water using the open excavation pit as the injection point; (7b) collecting and treating the flush fluid along with the source ground water through the source extraction well and chemical treatment facility (as in step 5a); and (8) implementing institutional controls against use of contaminated ground water until cleanup goals are met. Statutory Determinations. The selected remedy is protective of human health and the environment, complies with Federal and State requirements that are legally applicable or relevant and appropriate to the remedial action, and is cost-effective. This remedy utilizes pennanent solutions and altemative treatment or resource recovery technologies, to the maximum extent practicable, and satisfies the statutory preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a principal element. Although this remedy will not result in hazardous substances remaining on-site above health- based levels, a review will be conducted within five years after commencement ofthe remedial action to ensure that the remedy continues to provide adequate protection of human health and the environment. Five-Year Reviews will continue to be conducted until cleanup goals are obtained and unlimited use ofthe site is permissible. The following information is included in the Decision Summary of this ROD. Additional information may be found in the Administrative Record file for this Site. • Chemicals of concem (COCs) and their respective concentrations (Tables 1-4, pages 63-64); • Baseline risk represented by the COCs (Tables 10-12, pages 70-72); • Cleanup goals established for COCs and the basis for these levels (Tables 13 and 14, page 73); • How source materials constituting principal threats are addressed (page 48); • Current and reasonably anticipated future land use assumptions and current and potential future beneficial uses of ground water used in the Baseline Risk Assessment (BRA) and ROD (page 14); , • Potential land and ground water use that will be available at the Site as a result ofthe Selected Remedy (page 55); Estimated capital, annual operation and maintenance (O&M), and total present worth costs, discount rate, and the number of years over which the remedy cost estimates are projected (Tables 18 and 19, pages 84 through 87); and Key factor(s) that led to selecting the remedy (i.e., describing how the Selected Remedy provides the best balance of tradeoffs with respect to the balancing and modifying criteria, highlighting criteria key to the decision) (page 43). Authoriziiig-Signatures director Date Superfund Division U.S. Environmental Protection Agency, Region 4 Record of Decision Summary of Remedial Altemative Selection Smalley-Piper Superfund Site September 2008 TABLE OF CONTENTS ACRONYMS and ABBREVIATIONS iv 1.0 SiteName, Location, and Description 1 2.0 Site History and Enforcement Activities 2 2.1 Site History 2 2.2 Enforcement History 3 3.0 Community Participation 5 4.0 Scope and Role of Response Action 6 5.0 Site Characteristics 7 5.1 Concepmal Site Model 7 5.2 Site Geologic and Hydrogeologic Conditions 7 5.3 Surface Water Hydrology 9 5.4 Nature and Extent of Contamination 9 5.5 Contaminant Fate and Transport 12 6.0 Current and Potential Future Land Use 14 6.1 Current Land Use 14 6.2 Current Ground Water Use 14 6.3 Potential Future Land Use 14 6.4 Potential Future Ground Water Use 14 7.0 Summary of Site Risks 15 7.1 Summary of Human Health Risk Assessment 15 7.2 Summary of Ecological Risk Assessment 19 8.0 Remedial Action Objectives 21 9.0 Description of Altematives 22 9.1 Detailed Remedial Altematives Evaluation 22 10.0 Comparative Analysis of Altematives 37 10.1 Description of Criteria 37 10.2 Evaluation of Altematives Using Threshold and Balancing Criteria 43 10.3 Principal Threat Waste 48 11.0 Selected Remedy 49 11.1 Rationale for the Selected Remedy 49 11.2 Description ofthe Selected Remedy 49 Record of Decision Summary of Remedial Altemative Selection Smalley-Piper Superfund Site September 2008 TABLE OF CONTENTS (Continued) 11.3 Five-Year Reviews , 54 11.4 Summary ofEstimated Remedy Costs 55 11.5 Expected Outcomes of the Selected Remedy 55 11.6 Future Land Use 55 11.7 Final Cleanup Goals 55 12.0 Statutory Determinations 56 12.1 Protection of Human Health and the Environment 56 12.2 Compliance with ARARs 56 12.3 Cost Effectiveness 59 12.4 Permanent and Altemative Treatment Solutions 59 12.5 Preference for Treatment as a Principal Element 59 12.6 Five-Year Review Requirement ; 59 12.7 Documentation of Significant Changes 60 References 61 TABLES Table 1 Data Summary for Subsurface Soil in the Concrete Building Area 63 Table 2 Data Summary for Subsurface Soil in the Self-Storage Facility Area 63 Table 3 Data Summary for Shallow Ground Water 63 Table 4 Data Summary for Deep Ground Water 64 Table 5 Non-Cancer Toxicity Data ~ Oral/Dermal 65 Table 6 Non-Cancer Toxicity Data ~ Inhalation 66 Table 7 Subchronic Non-Cancer Toxicity Data - Inhalation 67 Table 8 Cancer Toxicity Data ~ Oral/Dermal 68 Table 9 Cancer Toxicity Data ~ Inhalation 69 Table 10 Risk Characterization Summary for Current Off-Site Resident - Noncarcinogens 70 Table 11 Risk Characterization Summary for Future Constmction Worker - Noncarcinogens 71 Table 12 Risk Characterization Summary for Future On-Site Resident - Noncarcinogens 72 Table 13 Cleanup Goals for Ground Water 73 Table 14 Cleanup Goal for Subsurface Soil 73 Table 15 Cost Comparison of Remedial Altematives 73 Table 16 Chemical-Specific ARARs, Criteria, and Guidance 74 Table 17 Action-Specific ARARs, Criteria, and Guidance 75 Table 18 Estimated Remedy Constmction Costs