GOWANUS CANAL SUPERFUND SITE RECORD OF DECISION APPENDIX V RESPONSIVENESS SUMMARY Table of Contents INTRODUCTION ............................................................................................................. 1 SUMMARY OF COMMUNITY RELATIONS ACTIVITIES .............................................. 1 SUMMARY OF COMMENTS AND RESPONSES .......................................................... 2 Historical Discharges .................................................................................................... 4 Potentially Responsible Parties ................................................................................... 4 Sediment Transport and Deposition – Current Conditions in Canal ........................ 5 PCB Concentrations in Surface Sediment from Canal and Reference Area .......... 10 PCB Sources ............................................................................................................... 13 Source Characterization and Control ........................................................................ 14 Combined Sewer Overflows .......................................................................................... 16 Former Manufactured Gas Facilities ............................................................................. 17 Other Upland Properties ................................................................................................ 18 Surface Water ............................................................................................................... 19 Unpermitted Pipe Outfalls ............................................................................................. 20 Other Pipe Outfalls ...................................................................................................... 21 Former Manufactured Gas Plant Facility Cleanups.................................................. 21 Remediation Plan ........................................................................................................ 24 Dredging Specifics ...................................................................................................... 30 Nonaqueous Phase Liquid Expression ..................................................................... 36 Nonaqueous Phase Liquid and Dissolved Phase Loading of Active Cap .............. 37 Nonaqueous Phase Liquid Spatial Distribution........................................................ 40 Sediment Processing .................................................................................................. 45 Sediment Treatment/Disposal .................................................................................... 47 Sediment Remediation ................................................................................................ 49 Restoration of Turning Basins ................................................................................... 50 Canal Bottom Capping ................................................................................................ 50 Canal Bottom Cap Maintenance................................................................................. 51 Information on Commercial Availability of Sites to Treat Contaminated Sediment ...................................................................................................................... 52 Stabilization of Dredged Sediments .......................................................................... 52 Migration of Sediments During Remediation ............................................................ 57 Confined Disposal Facility ......................................................................................... 58 Upland Sources of Contamination............................................................................. 66 V-i Combined Sewer Overflows ....................................................................................... 67 Industrial Sources to Combined Sewer Overflow .................................................... 77 Characteristics of Combined Sewer Overflow Solids .............................................. 78 Combined Sewer Overflow Impacts on Sediments in Upper Reach of Canal ........ 81 Total Organic Carbon Content of Sediments ............................................................ 81 Fecal Coliform ............................................................................................................. 89 Volume of Solids from Combined Sewer Overflow Discharges .............................. 89 Radioisotope Profiles in Sediment Cores ................................................................. 96 Polycyclic Aromatic Hydrocarbon Composition ...................................................... 96 Combined Sewer Overflow Solids ............................................................................. 98 Flooding ..................................................................................................................... 103 Effectiveness and Locations of Retention Tanks ................................................... 106 Miscellaneous Retention Tank Concerns ............................................................... 113 Navigation .................................................................................................................. 123 RTA 1 .......................................................................................................................... 124 RTA 2 .......................................................................................................................... 124 Odors and Pathogens During Construction ........................................................... 126 Differing Conditions Along Canal ............................................................................ 129 Figure 8: PAH Distribution for Hot Spot and Non-hot Spot Locations ................. 129 Natural Attenuation for Remediation Target Area 3 ............................................... 130 Remedy Effectiveness .............................................................................................. 131 Dredging and Sediment Management Costs .......................................................... 133 Confirmatory Design Sampling and Testing Costs ................................................ 135 Remedial Design Costs ............................................................................................ 135 Pre-Remediation Site Work Costs ........................................................................... 135 Debris Management Costs ....................................................................................... 135 Space and Other Canal Constraints ........................................................................ 136 Long-Term Monitoring and Maintenance Program for Sediment Cap .................. 137 Pre-Design Investigation, Modeling, Treatability Testing and Pilot Testing ........ 137 Adaptive Management .............................................................................................. 137 Retention Tank Community Effects ......................................................................... 138 Community Involvement ........................................................................................... 138 Post-Remediation Restoration ................................................................................. 142 Sediment and Contaminant Mass Balance ............................................................. 143 V-ii Relative Magnitude of Polycyclic Aromatic Hydrocarbon Sources ...................... 145 Bathymetric Change Analysis .................................................................................. 146 Vessel Activity as Sediment Transport Mechanism ............................................... 146 Nonaqueous Phase Liquid Migration Estimates .................................................... 146 Watershed-Based Conceptual Site Model ............................................................... 147 Basis for Preliminary Remedial Goal Development–Ecological Toxicity Testing ....................................................................................................................... 147 Preliminary Remediation Goal Development Methodology ................................... 149 Preliminary Remediation Goals for Metals ............................................................. 150 Post-Remedy Sediment Transport and Deposition ................................................ 151 Potential Releases from Behind Bulkheads ........................................................... 157 Cost Burden for Bulkhead Upgrade/Stabilization .................................................. 158 Plan for Minimizing Bulkhead Upgrade/Stabilization Disruptions ........................ 159 General Bulkhead Concerns .................................................................................... 163 Bulkhead-Related Geotechnical and Groundwater Modeling Studies ................. 165 Sheet Piling for Bulkhead Upgrades and Restoration ........................................... 167 Sheet Piling for Temporary Cells ............................................................................. 168 Sediment Dredging Production Rate ....................................................................... 169 Current and Future Conditions ................................................................................ 169 Property Values ........................................................................................................