1. 1 FORMER COS COB POWER PLANT From Characterization to Redevelopment Brownfields2006 November 14, 2006

2. 2 Site History  Power Plant built in 1907 to provide electrification for the railroad  Coal fired plant operated until the 1960s  CT DOT decommissioned the plant in 1986  Property transferred to the Town in 1989  Buildings demolished in 2000

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4. 4 Site Investigation  Investigations conducted 1997, 1998  EPA –Targeted Brownfields Assessment, 2004  Use of Triad rapidly clarified the principal reuse questions and remedial options for the project team  Provided the basis for focused PCB characterization and removal  Phase III Remedial Investigation Focused Feasibility Study Report, 2005  Identified the extent and levels of contamination to meet state requirements  Identified the alternatives for remediation

5. 5 Targeted Brownfields Assessment, 2004 Utilizing Triad  Thorough characterization of multiple contaminants (TPH, PAHs, PCBs, Arsenic) in soil in a single mobilization of less than one week  Use of EPA Region 1 mobile laboratory for onsite PCB analysis and XRF screening for metals, UV Fluorescence test kits for PAH and TPH  Key ranges of concentrations and safety factors were identified and refined to guide data interpretation and decision-making in the field using real-time methods  These ranges became the focus of collaborative data collection using off-site methods to increase decision confidence

6. 6  Real time data indicated that surface soil consistently exceeded Connecticut's residential reuse criteria for TPH, PAHs, and Arsenic  Historical identification of coal ash fill to a depth of 30 feet reduced the need for deeper samples and indicated cleanup to residential standards was cost prohibitive  Dynamic work strategies allowed step-out sampling in grid elements to define extent of PCB contamination  Data suggesting that limited remedial action, combined with modification of the reuse alternatives could facilitate reuse. Targeted Brownfields Assessment, 2004 Utilizing Triad

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8. 8 Phase III Remedial Investigation Focused Feasibility Study Report, 2005  Focused sub-grid evaluation of PCB “hotspots” identified during TBA. Original 70X70’ grids subdivided into 10X10’ for delineation.  Additional site wide characterization to meet State concerns  Allowed quick determination of most appropriate remedial strategy

9. 9 PCB GRID SAMPLE RESULTS

10. 10 SITE WIDE SOIL RESULTS

11. 11 CTDEP and Federal Remediation Criteria  Soil  Direct exposure criteria  Residential (R DEC) * and Industrial / Commercial (I/C DEC)  Pollutant Mobility Criteria *  TSCA *  Groundwater  Groundwater Protection Criteria  Volatilization Criteria *  Surface Water Protection Criteria * * Applicable to site

12. 12 REMEDIATION CONCEPTS

13. 13 Remedial Alternatives  No Action  On-site Soil Treatment  Excavation and Off-site Disposal of All Contaminated Soils  Excavation and Off-site Disposal of Pollutant Mobility Criteria and TSCA Clean Up criteria exceeding Soils and Installation of Permanent Cap

14. 14 Selected Alternative - Excavation and Off-site Disposal of PMC and TSCA Exceeding Soils and Installation of Permanent Cap Advantages  Removes highly contaminated soils from site  Permanent cap eliminates direct contact with contaminated soil left on-site  Upon successful completion, site can be easily redeveloped  Selected alternative has been successfully implemented at many sites within CT  Most cost effective remedial alternative

15. 15 Density of Data from Triad Resulted in $200K Cleanup Grant  Data from TBA and Phase III RI was sufficient to allow Greenwich to apply for and receive a $200K Brownfields cleanup grant.  Grant was applied for phase I remediation and construction costs including “hot spot removal”, confirmation sampling, and oversight.  Grant funds were also used for public outreach

16. 16 Phase 1 Remediation – Completed 2005/06  Excavation and Off-site Disposal of Pollutant Mobility Criteria and TSCA Clean Up criteria exceeding Soils  Total Petroleum Hydrocarbon Impacted Soil – 175 tons  PCB Soil >50 mg/kg – 20 tons  PCB Soil >10 mg/kg and ≤ 50 mg/kg – 116 tons  On-site Relocation of PCB Soil (> 1 mg/kg and ≤ 10 mg/kg)  Total Construction Cost - $139,000

17. 17 PCB & ETPH SOIL REMEDIATION PLAN

18. 18 Phase 2 Remediation and Shoreline Stabilization  Installation of Permanent Earthen Cap to Render Existing Soils Inaccessible  Total Import of Soil – 45,000 cyd  Shoreline Stabilization and Earthen Cap Protection  Rehabilitation and Installation of Stone Revetment – 1,600 lf of Shoreline  Total Estimated Cost - $3.5M

19. 19 Phase 2 Remediation – Earthen Cap Material  Identification of Potential Earthen Cap Sources  Town of Greenwich Public Safety Center: 10,000 – 15,000 cyd  Connecticut Light & Power (CL&P) Glenbrook Cable: 30,000 – 40,000 cyd  CL&P Provided Items All Analytical Data Necessary for CTDEP Reuse Approval Transportation and Temporary Placement of Materials Installation and Maintenance of E&S Controls Material Processing Payment to Town ($250k - $500k)  Total Estimated Savings - $750k

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