23rd Annual NARPM Training Program
Passive SamplingCase Study: United
Heckathorn Superfund SiteRachelle S. Thompson, MS, PE
US EPA Region 9
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Presentation Outline
Site location and background Past remedial actions Current conditions Feasibility study Passive sampler deployments Preliminary results Next steps
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United Heckathorn Superfund Site
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Site Location
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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
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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.
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Mussel Trends
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Feasibility Study
Tier 1 Sediment Study
Tier 2 Sediment Study
Source Identification Study
DDT Fate & Transport Study
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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
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Tier 2 Sediment Study Current and turbidity
monitoring Particle tracking Sediment erosion
analysis Sediment transport
modeling
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Source Identification Study
Groundwater Embankments and seeps Pilings Undredged sediments Other sources
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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
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Passive Sampling Goals Evaluate spatial distribution of contamination Evaluate contaminant fate & transport and
potential sources Evaluate long-term monitoring options
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Types of Passive Samplers
Sediment: Polyethylene mounted in metal frame
Surface water: Polyethylene strips in mesh bag, co-deployed with mussels
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Sampling Locations Sediment locations: 2012
(purple) and 2013 (green) Water locations (additional
background point not shown)
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Deployment and Recovery September-October
2013 ERT dive team support
for sediment samplers Surface water samplers
deployed from boat
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PE
target
PRC
co
ncen
tra
tion
sediment porous medium
sediment porous medium
DPE DSED DSED
PE
target
PRC
co
ncen
tra
tion
0
position
sediment porous medium
sediment porous medium
KPESED
target PRCs target
at time = 0
Cpe = 0 for targets
at some later time, t measure PRC losses and Cpe(t) use results to find Cpe(t = ∞)
D
D D
D
D
D
DD
D
D
D
D D
D
D
D
DD
D
D
Performance Reference Compounds
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.
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Field Challenges Shutdown Boat logistics Poor visibility Channel depth Active channel
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4,4’-DDD, 4,4’-DDT, and 4,4’-DDE with depth into bed (ng/g PE)DDD dominant
4,4’-DDD 4,4’-DDE
4,4’-DDT
Vertical Chemical Profiles
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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
Gschwend
2013 modelingporewater conc’s
section 4 >1000 ng/L
section 3100 to 1000 ng/L
section 210 to 100 ng/L
section 1~ 10 ng/L
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Simple Mass Balance Estimate
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Site Monitoring- 2012
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Site Monitoring- 2013
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Surface Water
Filtered water PE-inferred
water concentration
Mussel- inferred water concentration
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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
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Next Steps
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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
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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 [email protected]