Record of Decision Amendment, Mohonk Road Industrial Plant

SDMinS Documennt 103694 RECOIU} OF DECISION AMENDMENT Mohonk Road Industrial Plant Superfvind Site Hamlet of High Falls, Towns of Marbletown and Rosendale Ulster County, New York United States Environmental Protection Agency- Region 2 New York, New York September 2008 500318 DECLAIUVTION FOR THE RECORD OF DECISION AMENDMENT SITE NAME AND LOCATION Mohonk Road Industrial Plant Site Superfund Identification Number: NYD986950012 Hamlet of High Falls, Towns of Marbletown and Rosendale, Ulster County, New York STATEMENT OF BASIS AND PURPOSE This decision document presents the amended remedy for the Mohonk Road Industrial Plant (MRIP) Superfund Site, which was chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended,42 U.S.C. §§ 9601-9675 and to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision document explains the factual and legal basis for amending the remedy for the Site. The information supporting this remedial action decision is contained in the Administrative Record. The index for the Administrative Record is attached to this document (APPENDIX III) . The New York State Department of Environmental Conservation (NYSDEC) concurs with the amended remedy. A letter of concurrence from NYSDEC is attached to this document (APPENDIX IV). ASSESSMENT OF THE SITE The response action selected in this Record of Decision Amendment (ROD Amendment) is necessary to protect the public health or welfare or the environment from actual or threatened releases of hazardous substances into the environment at or from the Site. DESCRIPTION OF THE SELECTED REMEDY The amended remedial action described in this document addresses contaminated groundwater at the Mohonk Road Industrial Plant Site. The Site includes the Mohonk Road Industrial Plant property (MRIP Property) as well as those areas impacted by the groundwater plume emanating from the property. This remedial action amends the selected remedy presented in the March 31, 2000 Record of Decision (ROD) and undertaken by EPA to address Site groundwater. The primary change in the groundwater remedy is associated with replacing the active extraction and treatment of groundwater from within the far field plume with monitored natural attenuation. Amended Groundwater Remedy The amended groundwater remedy includes: o Monitored natural attenuation within the far field plume to restore the aquifer to its most beneficial use (as a potable water supply), 1 500319 and continued extraction of contaminated groundwater in the near field plume on the MRIP Property, subsequent treatment with an air stripper and activated carbon adsorption, and discharge of the treated water to Coxing Kill Creek. The near field plume refers to that portion of the groundwater plume with total volatile organic compound (VOC) concentrations greater than 1,000 parts per billion (ppb), while the far field plume has been updated to refer to the portion of* the groundwater plume with total VOC concentrations from 5 ppb to 1,000 ppb. o Implementation of a groundwater monitoring program to evaluate groundwater conditions and the effectiveness of the components of the remedy. o Institutional controls in the form of existing governmental controls to prevent future use of the aquifer as a drinking water source in the impacted or threatened area. These institutional controls would no longer be necessary following the restoration of the groundwater to beneficial use. o Continued operation of the Site soil vapor extraction system and vapor mitigation system. The ROD included an alternate water supply as part of the groundwater remedy, and also specified a source control action. Since the issuance of the ROD, the source control and alternate water supply actions have been implemented. This ROD Amendment focuses only on that portion of the selected remedy (dealing with groundwater) to which a fundamental change is warranted, and the rationale for such change. DECLARATION OF STATUTORY DETERMINATIONS The modified remedy meets the requirements for remedial actions set forth in CERCLA §121. It 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. The selected remedy utilizes permanent solutions and alternative treatment technologies to the maximum extent practicable, and the groundwater remedy also satisfies the statutory preference for treatment as a principal element of the remedy (i.e., it reduces the toxicity, mobility, or volume of hazardous substances, pollutants, or contaminants as a principal element through treatment). Because this remedy will not result in hazardous substances, pollutants, or contaminants remaining on-site above levels that allow for unlimited use and unrestricted exposure, but will take more than five years to attain remedial action objectives and cleanup levels in the groundwater, a policy review will be conducted no less often than once every five years after completion of the construction of the remedial action components for the Site to ensure that the remedy is, or will be, protective of human health and the environment. 500320 DATA CERTIFICATION CHECKLIST The Decision Summary for this ROD Amendment contains the. remedy selection information noted below. More details may be found in the Administrative Record file established for the MRIP Site. o Chemicals of concern (COCs) and their respective concentrations (see Appendix II); . o Baseline risk represented by the COCs (see page 11 herein; also see pages 18 through 24, and Tables 8 through 13 on pages 11-44 through 11-64 of the ROD); o Cleanup levels established for chemicals of concern and the basis for these levels (see Appendix II; also see pages 15, 23, 25 and 26 herein, and Table 14 on page 11-65 of the ROD) ; o How source materials constituting principal threats are addressed (see page 48 of the ROD); o Current and reasonably anticipated future land use assumptions and current and potential future beneficial uses of groundwater used in the baseline risk assessment and ROD (see page 10 herein; also see pages 17 and 18 of the ROD); o Potential land and groundwater use that will be available at the Site as a result of the selected remedy (see page 23 herein; also see pages 54 and 55 of the ROD); o Estimated capital, annual operation and maintenance, and total present worth costs, discount rate, and the number of years over which the remedy cost estimates are projected (see Appendix II herein); and, o Key factor(s) that led to selecting the remedy (i.e., how the selected remedy provides the best balance of tradeoffs with respect to the balancing and modifying criteria, highlighting criteria key to the decision)(see pages 20-23 herein). AUTHORIZING SIGNATURE ?/?c>/<:^^ George Pavlou, Acting Director Date Emergency & Remedial Response Division 500321 DECISION SUMMARY Mohonk Road Industrial Plant Superfund Site Hamlet of High Falls, Towns of Marbletown and Rosendale Ulster County, New York United States Environmental Protection Agency Region 2 "New York, New York September 2008 500322 TABLE OF CONTENTS SITE NAME, LOCATION AND DESCRIPTION 1 SITE HISTORY AND ENFORCEMENT ACTIVITIES 1 HIGHLIGHTS OF COMMUNITY PARTICIPATION 5 SCOPE AND ROLE OF RESPONSE ACTION 6 SUMMARY OF SITE CHARACTERISTICS . 6 CURRENT AND POTENTIAL FUTURE LAND AND RESOURCE USERS 11 SUMMARY OF SITE RISKS 11 REMEDIAL ACTION OBJECTIVES 14 DESCRIPTION OF GROUNDWATER RESPONSE ALTERNATIVES 14 EVALUATION OF ALTERNATIVES 20 PRINCIPAL THREAT WASTES 23 SELECTED REMEDY 23 STATUTORY DETERMINATIONS 25 DOCUMENTATION OF SIGNIFICANT CHANGES 27 ATTACHMENTS APPENDIX I. FIGURES I APPENDIX II. TABLES II APPENDIX III. ADMINISTRATIVE RECORD INDEX Ill APPENDIX IV. STATE LETTER OF CONCURRENCE IV APPENDIX V. RESPONSIVENESS SUMMARY V 500323 SITE NAME, LOCATION AND DESCRIPTION The Mohonk Road Industrial Plant (MRIP) Superfund Site (the Site) is located in the Hamlet of High Falls, Ulster County, New York, approximately seven miles north- northwest of the Village of New Paltz and ten miles south- southwest of the City of Kingston. The Hamlet of High Falls is situated within two townships; the Towns of Marbletown and Rosendale (see Figure 1) . The Site was added to the National Priorities List (NPL) on January 19, 1999; the Superfund identification number for the Site is NYD986950012. The New York State Department of Environmental Cohs^ervaeibh^lKYSDECreserved aiS" the" lead agency forTthe-Remedloii—Investigation -and- - Feasibility Study (RI/FS) which was initiated prior to the Site being placed on the NPL. The United States Environmental Protection Agency (EPA) assumed the role as lead agency with issuance of the Record of Decision (ROD) on March 31, 2000. The Site includes a facility located at 186 Mohonk Road (the MRIP Property), and all surrounding properties that have been impacted by the contaminated groundwater plume. The MRIP Property originally consisted of approximately 14.5 acres of mostly undeveloped land with a 43,000 square foot building in its southern corner. As part of the water supply remedy, and consistent with the ROD, 6.9 acres of the northern property were conveyed by the Kithkin Corporation on August 19, 2005 to the High Falls Water District. This northern portion of the property is now the location of the High Falls Water District's drinking water treatment plant. The Site-related groundwater plume extends approximately 4,000 feet downgradient from the MRIP Property, and had adversely impacted at least 75 residential and commercial water supply wells. Residents and businesses within the area are now obtaining their potable water from the High Falls Water District, a publicly- operated water supply system. The "near field plume" as historically defined in the ROD refers to that portion of the groiindwater plume with total volatile organic compound (VOC) concentrations greater than 1,000 parts per billion (ppb), while the "far field plume" refers to the component of the groundwater plume between 10 ppb and 1,000 ppb total VOCs. Figure 4 depicts the current extent of the plume boundary to the 5 ppb total VOC concentration.

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