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Passive Sampling Case Study: United Heckathorn Superfund Site

Passive Sampling Case Study: United Heckathorn Superfund Site. Rachelle S. Thompson, MS, PE US EPA Region 9. Presentation Outline. Site location and background Past remedial actions Current conditions Feasibility study Passive sampler deployments Preliminary results Next steps.

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Passive Sampling Case Study: United Heckathorn Superfund Site

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  1. Passive SamplingCase Study: United Heckathorn Superfund Site Rachelle S. Thompson, MS, PE US EPA Region 9

  2. Presentation Outline • Site location and background • Past remedial actions • Current conditions • Feasibility study • Passive sampler deployments • Preliminary results • Next steps

  3. United Heckathorn Superfund Site

  4. Site Location

  5. Cleanup History • Initial response (1990-1998) • 3,300 cubic yards of DDT-contaminated soil removed from upland area • Dredged 107,000 cubic yards of contaminated sediment (3 tons DDT) from Lauritzen Channel and Parr Canal • Capped upland area with concrete to prevent erosion • Monitoring and additional investigations • Sampling of fish, mussels, sediment, and water • Five Year Reviews in 2001, 2006, and 2011

  6. Current Status • The upland cap remains intact and protective. • DDT levels in the Inner Richmond Harbor, Santa Fe Channel and Parr Canal have decreased significantly. • DDT levels in Lauritzen Channel pose a potential long-term risk to human health through consumption of fish. • DDT levels in Lauritzen Channel pose a potential ecological risk to fish-eating birds and mammals.

  7. Mussel Trends

  8. Feasibility Study • Tier 1 Sediment Study • Tier 2 Sediment Study • Source Identification Study • DDT Fate & Transport Study

  9. Tier 1 Sediment Study • Multi-beam and side-scan sonar create images of the channel bottom • Areas of deposition and erosion of sediment • Natural and anthropogenic forces

  10. Tier 2 Sediment Study • Current and turbidity monitoring • Particle tracking • Sediment erosion analysis • Sediment transport modeling

  11. Source Identification Study • Groundwater • Embankments and seeps • Pilings • Undredged sediments • Other sources

  12. DDT Fate & Transport Study • Passive samplers • Sediment cores • Trends • Sources and sinks • Approximately 66,000 yd3 of contaminated sediment in Lauritzen Channel • Approximately 350 kg of DDT in those sediments

  13. Passive Sampling Goals • Evaluate spatial distribution of contamination • Evaluate contaminant fate & transport and potential sources • Evaluate long-term monitoring options

  14. Types of Passive Samplers • Sediment: Polyethylene mounted in metal frame • Surface water: Polyethylene strips in mesh bag, co-deployed with mussels

  15. Sampling Locations • Sediment locations: 2012 (purple) and 2013 (green) • Water locations (additional background point not shown)

  16. Deployment and Recovery • September-October 2013 • ERT dive team support for sediment samplers • Surface water samplers deployed from boat

  17. Performance Reference Compounds targetPRCstarget at time = 0 Cpe = 0 for targets at some later time, t measure PRC losses and Cpe(t) use results to find Cpe(t = ∞) Laboratory method: Gshwend, P. et al, Passive PE Sampling in Support of In Situ Remediation of Contaminated Sediments: Standard Operating Procedure for PED Preparation, December 2012.

  18. Field Challenges • Shutdown • Boat logistics • Poor visibility • Channel depth • Active channel

  19. Vertical Chemical Profiles 4,4’-DDD, 4,4’-DDT, and 4,4’-DDE with depth into bed (ng/g PE) DDD dominant 4,4’-DDT 4,4’-DDE 4,4’-DDD

  20. Spatial Distribution • Bottom water and pore water concentrations (ng/L 4,4’-DDD) • Strong gradient down channel • Every channel station has porewater > bottomwater • Bed-to-water column fluxes

  21. Simple Mass Balance Estimate

  22. Site Monitoring- 2012

  23. Site Monitoring- 2013

  24. Surface Water • Filtered water • PE-inferred water concentration • Mussel- inferred water concentration

  25. Preliminary Conclusions • Porewater DDx concentrations are highest in the northern reach of the channel • There is a high degree of uncertainty in the mass balance modeling, but there appears to be an ongoing source mid-channel • Water-column passive samplers could potentially be used for long-term monitoring at the site

  26. Next Steps

  27. Acknowledgements • CH2MHILL- Brenda McConathy, Patricia White • E2- Tamara Frank • EPA Region 9 Lab- Andy Lincoff • ERT Dive Team – Steve Blaze, Alan Humphrey, Scott Grossman, Chris Gallo, John McBurney • Massachusetts Institute of Technology- Phil Gshwend, Patricia Tcaciuc • Sea Engineering Inc.- Craig Jones • US Army Corps of Engineers- Karl Gustavson, Earl Hayter

  28. Questions? • Additional information • epa.gov/region09/unitedheckathorn • Contact information • Rachelle S. Thompson, MS, PE Superfund Division US EPA Region 9 75 Hawthorne Street, SFD-7-3 San Francisco, CA 94105 415-972-3962 thompson.rachelle@epa.gov

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