Identifying and Managing Key Cost Drivers During Investigation, Remedy Selection and Design at Contaminated Sediment Sites

Transcription

1 Identifying and Managing Key Cost Drivers During Investigation, Remedy Selection and Design at Contaminated Sediment Sites Doug Crawford, PE Kendrick Jaglal, PE Brian White, PE Steve Anagnost, PE Trevor Staniec

2 AGENDA Sediment remediation overview Data collection Remedy selection and design Closing thoughts

3 Sediment Remediation Overview

4 Contaminated sediment significant environmental problem Contributing factor to fish advisories Sediment Remediation Overview Over 3,200 fish consumption advisories issued nationwide (EPA, 2016) Cleanups under CERCLA, RCRA, WRDA and various State programs Cleanups selected at over 150 CERCLA / Superfund sediment sites as of 2016

5 COST ($B) Case for Proactive Management of Site-Specific Cost Drivers Sediment remediation costs can be substantial Relatively minor changes can result in significant savings and / or improve cost predictability 0 Review cost drivers at each project stage Optimize approach at each of the stages

6 Data Collection

7 Relative Percentage of Overall Project Cost Important to Have a Complete Dataset Investigation Design Construction

8 Site Characteristics impacting cost Access Limitations Low draft Boat traffic Obstructions Bridges Power lines

9 Site Characteristics impacting cost Debris Vegetation Navigation channel Hard bottom Fish spawning windows

10 Sediment Characteristics that can impact cost Single or multiple contaminant classes Contaminant distribution in sediment Contaminants with threshold drivers e.g. PCBs Geotechnical properties Potential for air impacts and odors

11 Using Key Site-specific Data to Save Removal Cost by Supporting No Action State required the presumptive remedy of sediment removal Site-specific data and conditions used to support no action Solubility Reduced dissolution at lower local average temperatures Lower solubility of hydrophobic compounds Partitioning Aging effects reduce rate of desorption High partition coefficients for PAHs overall Ongoing atmospheric contributions Coal tar parking lot sealant PAH contributions

12 Remedy Selection / Design

13 Surface Sediment Holds the Key to Risk Reduction

14 Substantial removal may still be insufficient Mass reduction 99.7% Risk potential 200% increase Sensible Solutions (Fox River Group, 1999)

15 Alternative Technologies Carbon Layer Combination remedies Addresses various zones of a site Same protectiveness but less costly than dredging Carbon Includes use of in situ and passive technologies Monitored natural recovery (MNR) Enhanced MNR Capping Activated carbon treatment In situ stabilization / treatment Amended capping Modified from cetco.com.au

16 Hendrix Street Canal, NY Combination Remedies Dredging and Capping Grasse River, NY 7,000 feet length Sediments acutely toxic to aquatic life Hydraulic sediment dredging Containment cap to cover residuals Limited available landside area - Staged equipment, debris, and sand stockpiles on barges ROD 2013 ($200 million ±) 100,000 cubic yards (cy) of near shore dredging and backfill 2-foot-thick armored caps over 59 acres that are subject to ice jams 225 acres of 1-foot-thick sand cap in other areas of the river On-site landfill disposal

17 Combination Remedies In Situ Treatment IMTT Bayonne Shipping Canal, NJ Gowanus Canal, NY Canal 75 feet in width and 1,400 feet in length North Cell Sheet pile cutoff wall In situ solidification/stabilization Multi-layer containment cap South Cell Mechanical dredging Disposal in northern cell Carbon amended sand cap 2013 ROD ($500 million +) CSO source control (30 to 70% reduction) 600,000 cy of dredging Multi-layer armored cap In situ solidification / stabilization of NAPL in native sediment Off-site treatment and disposal Source: Gowanus Canal ROD

18 Combination Remedies Onondaga Lake, NY Multiple zones within site Hydraulically dredge 2.65 million cy Isolation cap 460 acres GAC and siderite (ph) amendment MNR 2,000 acres Nitrate addition inhibit MeHg release On-site sediment management Habitat restoration Capping / Amended Capping and MNR / ENR Lower Duwamish Waterway, WA 2014 ROD ($342 million ±) Concurrent source control 960,000 cy of dredging over 105 acres with off-site landfill disposal Engineered cap over 24 acres ENR enhanced natural recovery by placing 6 to 9-inch sand layer over 48 acres Activated carbon pilot study MNR - monitored natural recovery (235 acres)

19 Closing thoughts Proactively manage cost drivers at each project stage Collect sufficient data to reduce uncertainty Integrate flexibility and lower cost components during remedy selection / design

20 OBG THERE S A WAY Questions? Thank you! Doug Crawford, PE Doug.Crawford@OBG.com