Department of Environmental Conservation Division of Environmental Remediation Record of Decision Niagara Mohawk Rome - Kingsley Avenue Former Manufactured Gas Plant Site Operable Unit 1: Former Plant Site Rome (C), Oneida County, New York Site No. 6-33-043 March 2002 New York State Department of Environmental Conservation GEORGE E. PATAKI, Governor ERIN M. CROTTY, Commissioner DECLARATION STATEMENT - RECORD OF DECISION Niagara Mohawk Rome - Kingsley Avenue Former Manufactured Gas Plant Site Operable Unit 1: Former Plant Site Inactive Hazardous Waste Site Rome (C), Oneida County, New York Site No. 6-33-043 Statement of Purpose and Basis The Record of Decision (ROD) presents the selected remedy for the Niagara Mohawk (NIMO) Rome - Kingsley Avenue Former Manufactured Gas Plant (MGP), Operable Unit No. 1 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 NIMO Rome - Kingsley Avenue Former MGP inactive hazardous waste disposal site and upon 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 Niagara Mohawk (National Grid) Rome - Kingsley Avenue Former MGP, Operable Unit No. 1 and the criteria identified for evaluation of alternatives, the NYSDEC has selected source area removal and containment. The components of the remedy are as follows: < Excavation of approximately 21,100 cubic yards of contaminated source area soils. Excavated materials will be transported off-site for thermal treatment and/or disposal in accordance with applicable regulations; < Removal of a tar well and manufactured gas distribution and relief holder foundations; < Subsurface containment and removal of remaining on-site DNAPL and in-situ groundwater treatment, using a partially perforated cutoff wall, at the western property boundary adjacent to the Mohawk River; < A soil cover over approximately 14 acres on the northern portion of the site; < Removal of approximately 800 cubic yards of contaminated sediment in the backwater area and replacement with clean material, comparable to the native sediment; < Excavation and off-site disposal of purifier waste not addressed by the purifier disposal area Interim Remedial Measure (IRM); < Excavation of approximately 90 cubic yards of surface soil from three small areas on the Niagara Mohawk property outside the extent of the soil cover; < A long term operation, maintenance and monitoring program to include; monitoring and removal of DNAPL along the cutoff wall, groundwater treatment at the gates of the cutoff wall; establishment of a groundwater monitoring well network, and inspection and repair of the soil cover. < Institutional controls to limit future site development to commercial or industrial use and prevent future exposures to site contaminants. Annual certification to ensure that institutional controls are in place and effective. 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 ............................................4 4: Site Contamination ......................................................4 4.1 Summary of Remedial Investigation ...................................4 4.2 Interim Remedial Measures .........................................10 4.3 Summary of Human Exposure Pathways...............................10 4.4 Summary of Environmental Exposure Pathways.........................11 5: Enforcement Status .....................................................11 6: Summary of the Remediation Goals ........................................11 7: Summary of the Evaluation of Alternatives...................................12 7.1 Description of Remedial Alternatives .................................12 7.2 Evaluation of Remedial Alternatives..................................16 8: Summary of the Selected Remedy..........................................21 9: Highlights of Community Participation......................................24 Tables - Tables 1A-D: Nature and Extent of Contamination ................26 - Table 2: Remedial Alternative Costs .......................30 Figures - Figure 1: Site Map .........................................31 - Figure 2: Present Site Conditions ..............................32 - Figure 3: Alternative 2 - Capping ..............................33 - Figure 4: Alternative 4 - Source Removal and Containment..........34 - Figure 5: Location and Configuration of DNAPL Cutoff Wall ........35 - Figure 6: TAGM 4046 Exceedances Outside Proposed Cap ..........36 - Figure 7: Flood Boundary and Floodway .........................37 Appendix - Appendix A: Responsiveness Summary ........................38 - Appendix B: Administrative Record...........................52 RECORD OF DECISION Niagara Mohawk Rome - Kingsley Avenue Former Manufactured Gas Plant Site Operable Unit 1: Former Plant Site Rome (C), Oneida County, New York Site No. 6-33-043 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 has selected this remedy to address the significant threat to human health and/or the environment created by the presence of hazardous waste at Operable Unit No. 1 (OU1) of the Niagara Mohawk Rome - Kingsley Avenue Former Manufactured Gas Plant (MGP), a class 2 inactive hazardous waste disposal site. OU1 consists of the Former MGP site and the undeveloped state owned land adjacent to the site. As more fully described in Sections 3 and 4 of this document, operation of the former manufactured gas plant has resulted in the disposal of a number of hazardous wastes or substances at the site, including benzene and polycyclic aromatic hydrocarbons (PAHs), some of which were released or have migrated from the site to surrounding areas, including the sediment in the backwater area and soils in the state owned area adjacent to the site and groundwater. These disposal activities have resulted in the following significant threats to the public health and the environment: • a significant threat to human health associated with the potential for exposure due to direct contact with contaminated surface or subsurface soils and sediments. • a significant threat to human health from the potential for ingestion or contact with contaminated groundwater. • a significant threat to human health from the potential for inhalation or contact with dust from the site. • a significant environmental threat associated with contaminant levels in soil and sediment that have the potential to cause significant adverse acute or chronic effects to benthic organisms and other wildlife. • a significant environmental threat associated with the migration of light and dense non- aqueous phase liquid (LNAPL/DNAPL) and dissolved phase contaminants in groundwater from the site. NIMO Rome - Kingsley Avenue Former MGP Inactive Hazardous Waste Site March 27, 2002 RECORD OF DECISION Page 1 In order to eliminate or mitigate the significant threats to public health and the environment that the hazardous wastes disposed at the Rome Kingsley Avenue Site have caused, the following remedy was selected: • Excavation of approximately 21,100 cubic yards of source area soils heavily saturated with LNAPL and DNAPL for off-site thermal treatment and/or disposal in accordance with applicable regulations; • Removal of a tar well and the manufactured gas distribution and relief holder foundations; • Subsurface containment and removal of remaining on-site DNAPL and in-situ groundwater treatment, using a partially perforated cutoff wall, at the western property boundary adjacent to the Mohawk River; • A soil cover over approximately 14 acres on the northern portion