Department of Environmental Conservation Division of Environmental Remediation Record of Decision Operable Unit 2 - Coney Island Creek Former Brooklyn Borough Gas Works Site Coney Island, Kings County, New York Site No. 2-24-026 March 2002 New York State Department of Environmental Conservation GEORGE E. PATAKI, Governor Erin M. Crotty, Commissioner DECLARATION STATEMENT - RECORD OF DECISION Former Brooklyn Borough Gas Works Site Operable Unit 2 - Coney Island Creek Site No. 2-24-026 Statement of Purpose and Basis The Record of Decision (ROD) presents the selected remedy for the Former Brooklyn Borough Gas Works Site Operable Unit 2, a class 2 inactive hazardous waste disposal site which was chosen in accordance with the New York State Environmental Conservation Law. The remedial program selected is not inconsistent with the National Oil and Hazardous Substances Pollution Contingency Plan of March 8, 1990 (40CFR300). This decision is based on the Administrative Record of the New York State Department of Environmental Conservation (NYSDEC) for the Former Brooklyn Borough Gas Works Site Operable Unit 2 and consideration of public input to the Proposed Remedial Action Plan (PRAP) presented by the NYSDEC. A listing of the documents included as a part of the Administrative Record is included in Appendix B of the ROD. Assessment of the Site Actual or threatened release of hazardous waste constituents from this site, if not addressed by implementing the response action selected in this ROD, presents a current or potential significant threat to public health and the environment. Description of Selected Remedy Based on the results of the Remedial Investigation/Feasibility Study (RI/FS) for the Former Brooklyn Borough Gas Works Site Operable Unit (OU) 2 and the criteria identified for evaluation of alternatives, the NYSDEC has selected removal of the upper level of sediments in the study area of the Creek and replacement with clean sediment quality material. The components of the remedy are as follows: • The top three feet of contaminated sediments across the entire length and width of the OU 2 reach of the Creek adjacent to the site will be excavated and dewatered for off-site treatment/disposal or placement under the cap system, as provided for by the ROD for OU 1. An estimated 34,000 cubic yards of impacted sediment will be removed; • The areas excavated will be capped with up to three feet of sediment-quality material, such as sand and/or silty-sand material. The cap will include a filter fabric or geotextile between any residual contaminated sediment and clean materials placed; • Restoration of the Coney Island Creek bank along the OU1 site to remove contaminated materials and to provide a 50-foot wide ecological buffer zone, consistent with the requirements already established in the OU 1 ROD; and • A long term monitoring program will be implemented to assure the effectiveness of the proposed remedy including the three foot cap system. As part of the monitoring, Keyspan will collect both sediment and surface water samples for laboratory analysis, perform a bathymetric survey and conduct modeling. New York State Department of Health Acceptance The New York State Department of Health concurs with the remedy selected for this site as being protective of human health. Declaration The selected remedy is protective of human health and the environment, complies with State and Federal requirements that are legally applicable or relevant and appropriate to the remedial action to the extent practicable, and is cost effective. This remedy utilizes permanent solutions and alternative treatment or resource recovery technologies, to the maximum extent practicable, and satisfies the preference for remedies that reduce toxicity, mobility, or volume as a principal element. _______________________ _________________________________ Date Michael J. O'Toole, Jr., Director Division of Environmental Remediation TABLE OF CONTENTS SECTION PAGE 1: Summary of the Record of Decision .........................................1 2: Site Location and Description ..............................................2 3: Site History ............................................................3 3.1 Operational/Disposal History...................................3 3.2 Remedial History ............................................3 4: Site Contamination ......................................................3 4.1 Summaryo fR emedial Investigation ...................................4 4.2 Interim Remedial Measures ..........................................7 4.3 Summary of Human Exposure Pathways................................7 4.4 Summary of Environmental Exposure Pathways..........................8 5: Enforcement Status ......................................................8 6: Summary of the Remediation Goals .........................................8 7: Summary of the Evaluation of Alternatives....................................9 7.1 Description of Remedial Alternatives .................................10 7.2 Evaluation of Remedial Alternatives..................................12 8: Summary of the Selected Remedy..........................................15 9: Highlights of Community Participation......................................18 Tables - Table 1 Nature and Extent of Contamination ...........................19 Table 2 Remedial Alternative Costs ..................................20 Figures - Figure 1: Site Location Map ..................................21 - Figure 2: Site Plan ..........................................22 - Figure 3: Alternative 3.......................................23 - Figure 4: Alternative 4.......................................24 Appendix - Appendix A: Responsiveness Summary ........................25 - Appendix B: Administrative Record...........................36 RECORD OF DECISION FORMER BROOKLYN BOROUGH GAS WORKS SITE Operable Unit 2 - Coney Island Creek Kings County, New York Site No. 2-24-026 March 2002 SECTION 1: SUMMARY OF THE RECORD OF DECISION The New York State Department of Environmental Conservation (NYSDEC) in consultation with the New York State Department of Health (NYSDOH) has selected a remedy to address the significant threats to human health and the environment created by the presence of hazardous waste at the study area of the Coney Island Creek (see Figure 2) referred to as Operable Unit (OU) 2 of the former Brooklyn Borough Gas Works Site. The Study area of the Coney Island Creek is a portion of the Creek adjacent to the former Brooklyn Borough Gas Works which is a class 2 inactive hazardous waste disposal site. Contamination at the former Brooklyn Borough Gas Works site (designated Operable Unit 1) was addressed by a Record of Decision (ROD) issued by NYSDEC in March 2001, which will require remediation of the site as detailed in the ROD As more fully described in Sections 3 and 4 of this document, the operation of a manufactured gas plant (MGP) at the former Brooklyn Borough Gas Works Site resulted in the Creek contamination by a number of hazardous wastes including coal tar, benzene, toluene, ethylbenzene, xylene, polycyclic aromatic hydrocarbons, and non-aqueous phase liquid. These contaminants from the former were released or have migrated from the site into Coney Island Creek, resulting in surface water and sediment contamination above standards, criteria, and guidance values (SCGs). These operations have resulted in the following significant threats to the public health and the environment: • Adverse acute or chronic effect to fish, shellfish, crustacea and other wildlife; and • Potential human exposures to site-related contaminants through contact with contaminated surface water and sediments and/or the consumption of contaminated fish from the creek. To restore Coney Island Creek to predisposal conditions to the extent feasible and authorized by law, but at a minimum to eliminate or mitigate significant threats to the human health and the environment caused by site-related contaminants in the Creek, and to prevent potential future exposures to the public, the NYSDEC has selected the following remedy for OU 2 of the Brooklyn Borough Gas Works Site: Former Brooklyn Borough Gas Works Site - OU 2 Coney Island Creek, Site No. 2-24-026 March 25, 2002 RECORD OF DECISION Page 1 • The top three feet of contaminated sediments across the entire length and width of the OU 2 reach of the Creek adjacent to the site will be excavated and dewatered for off-site treatment/disposal or placement under the cap system, as provided for by the ROD for OU 1. An estimated 34,000 cubic yards of impacted sediment will be removed; • The areas excavated will be capped with up to three feet of sediment-quality material, such as sand and/or silty-sand material. The cap will include a filter fabric or geotextile between any residual contaminated sediment and clean materials placed; • Restoration of the Coney Island Creek bank along the OU1 site to remove contaminated materials and to provide a 50-foot wide ecological buffer zone, consistent with the requirements already established in the OU 1 ROD; and • A long term monitoring program will be implemented to assure the effectiveness of the proposed remedy including the three foot cap system. As part of the monitoring, Keyspan will collect both sediment and surface water samples for laboratory analysis, perform a bathymetric survey and conduct modeling. The selected remedy, discussed in detail in Section 8 of this document, is intended to attain the remediation goals selected for this operable