Greenwich Mohawk Brownfield

Transcription

1 Greenwich Mohawk Brownfield Remedial Options Feasibility Study Prepared for The Corporation of the City of Brantford

2 Phase One & Two Environmental Site Assessment Greenwich Mohawk Brownfield consists of three properties: 347 Greenwich Street (11.3 ha) 22 Mohawk Street (3.0 ha) 66 Mohawk Street (6.3 ha) 20.6 ha (51 ac) total Subsurface investigation (400+ sampling locations) confirmed contamination in soil & groundwater from historical industrial uses

3 Known Contamination (Vertical Profile) Rubble Fill Material: Mixed Soil with some Iron debris Cinders Bricks & Blocks Metals (lead, zinc, etc.) Concrete Slab Rubble 5 feet thick Sand Groundwater 2 to 10 feet thick Oils/Solvent (xylene) Clay

4 Known Contamination (Historical/Extent of Impact) Planned redevelopment for residential, parkland, institutional - Next Step? Remediate to MOE Generic Standards $210,000,000 (Class 5 Est.) Remediate to Property Specific Standards (PSS) $15,800,000 (Class 5 Est.)

5 Remediation Generic (Off-Site Disposal) Metals /Oils Groundwater Monitoring Landfill Gas Control Metals Oils/Gas/Diesel Remediation Metals / Oils Off-Site Management at 3 rd Party Receiver Cap Liner Clean Imported Fill Clean Dirt Gravel Pit

6 Remediation Now (Risk Assessment) Metals /Oils Groundwater Monitoring Soil Gas Control Metals Oils/Gas/Diesel Remediation Metals / Oils Off-Site Management at 3 rd Party Receiver Cap Liner Clean Imported Fill Clean Dirt Gravel Pit

7 Remediation GMB (Risk Assessment Scenario) Metals /Oils Excavation/ Off-Site Disposal Groundwater Monitoring Soil Gas Control Risk Assessment Metals Oils/Gas/Diesel Groundwater Remediation with Risk Management Measures Biopile Cap Metals Oils/Gas/Diesel Groundwater Oils/Gas/Diesel Groundwater On-Site Remediation Soil Vapour Extraction

8 Examples of Similar & Local Remedial Projects Hamilton Cambridge Sarnia Remediation included RA with Biopile and AS/SVE system; some excavation. RSC obtained. Property Sold Remediation included RA and limited excavation. RSC obtained. Derelict area transformed into productive use Remediation included RA with biopile, some excavation. Project is active.

9 Alternative to Generic Clean-up: Risk Assessment & Risk Management Measures (RMMs) i. RA develops Property Specific Standards (PSS) protective for site ii. Implementation: i. remediation required to meet PSS ii. land use controls called RMMs Administrative controls: e.g. soil management Conceptual engineered controls: e.g. Soft cap or Hard cap Elimination: e.g. building development restrictions; no basements

10 Known Contamination (Historical/Extent of Impact) will be reduced to Remediate to MOE Generic Standards $210MM +/-

11 Known Contamination (Historical/Extent of Impact) will be reduced to Oils & Xylenes Metals Remediate to PSS $15.8MM +/- Oils & Xylenes

12 Cost Opinion Summary for the Recommended Approach Key Activity Reasonable Minimum Cost Mobilization and Initial Activities $1,108,000 Site Preparation $929,000 Tank Removal $75,000 Soil Excavation, Disposal, and Backfilling $2,283,000 Air Sparging and Soil Vapour Main Variable affecting Extraction cost estimate Area and $3,060,000 Biopile Treatment volume of soil and $4,035,000 Water Management groundwater that has to be treated on site with $360,000 Subtotal (excluding HST) biopile, AS/SVE $11,850,000 Contingency and Inflation $3,941,000 Total (excluding HST) $15,791,000 Class 5 Opinion Range ( 50%, +100%) $7,895,500 to $31,582,000

13 Remediation RA completed to define PSS & RMM identified Remediation completed to remediate property to meet remedial targets and PSS Construction of caps and barriers not included Post remediation, properties will largely look similar to today Proposed land uses not acceptable until RMMs (cap) in place

14 Ballpark Costs for follow-on work RMM Implementation After Remediation Key Activity Ballpark Costs Negotiate CPU (1x) $15,000 Prepare Site Plan (1x) $25,000 Annual Report to MOE (Annual) $25,000 Site Security (e.g. fencing) (1x) $75,000 Groundwater Monitoring (3 $200,000 Soil Vapour (3 $150,000 Cap (variable based on redevelopment plans) (1x) $10,000,000 Maintenance of Cap (Annual) $10,000 Note: some of RMM costs are covered by developer or contractor

15 Proposed Schedule Class 3 Estimate to City (-20%/+30%)

16 Questions/Discussion