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PCBs Total Maximum Daily Loads San Francisco Bay Fred Hetzel SFB-RWQCB May 13, 2003.

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Presentation on theme: "PCBs Total Maximum Daily Loads San Francisco Bay Fred Hetzel SFB-RWQCB May 13, 2003."— Presentation transcript:

1 PCBs Total Maximum Daily Loads San Francisco Bay Fred Hetzel SFB-RWQCB May 13, 2003

2 Polychlorinated Biphenyls (PCBs) Impairment of San Francisco Bay PCBs on 303(d) list due to interim health advisory for fish consumption U.S. EPA California Toxics Rule- Human health risk assessment for fish consumption sets a total PCBs criteria in water at µg/L

3 PCBs Used in a Wide Range of Products Closed applications Capacitors and transformers Heat transfer and hydraulic fluids Open applications Plasticizers Surface coatings and paints Flame retardants Inks and adhesives Pesticide extenders Carbonless duplicating paper

4 Large Mass of PCBs in the Bay due to Past Activities

5 Link sources to endpoint Pollutant fate, transport, and effects processes Conceptual models TMDL Linkage Analysis

6 Generic Conceptual Model of PCBs Fate and Movement in Aquatic Systems (USEPA)

7 Atmospheric Deposition Point Sources Urban Runoff Spills & On-Land Contaminated Sites Delta Inflow Non-Urban Runoff & Non-Point Sources Surface Waters Biologically Active Sediment Layer Buried Sediment Layer Fish Benthic Invertebrates & Plants Fish eating Wildlife Benthic & Plant eating Wildlife Humans Bioturbation, Scouring, Deposition & Resuspension, Transport, Dredging Degradation, Sorption & Desorption, Diffusion Golden Gate Outflow PCBs TMDL Conceptual Model (Adapted from SETAC, 2002)

8 Atmospheric Deposition Point Sources Urban Runoff Spills & On-Land Contaminated Sites Delta Inflow Non-Urban Runoff & Non-Point Sources Surface Waters Biologically Active Sediment Layer Buried Sediment Layer Bioturbation, Scouring, Deposition & Resuspension, Transport, Dredging Degradation, Sorption & Desorption, Diffusion Golden Gate Outflow Long Term Fate Model

9 Surface Waters Biologically Active Sediment Layer Buried Sediment Layer Fish Benthic Invertebrates & Plants Fish eating Wildlife Benthic & Plant eating Wildlife Humans Food Web Model

10 Proposed Numeric Targets for PCBs Fish tissue = 23 parts per billion Based on human health risk assessment Sediment = 2.5 parts per billion Based on generic bioaccumulation factors Not specific to San Francisco Bay

11 PCBs Sources to the Bay Atmospheric deposition In–Bay sediment hot spots Dredging Treated wastewater Delta inflow Urban runoff & on land hot spots

12 Proposed PCBs Allocations Background and atmospheric deposition - 0 Hot spots - Sediment target (phased approach) - Source investigations Dredging - Sediment target (phased approach) - Source investigations Treated effluent - Current mass Run-off - Sediment target (phased approach) - Source investigations

13 Limited Options for Reducing PCBs Loads

14 Margin of Safety MOS incorporated implicitly in the implementation and monitoring plans Adaptive management approach to implementation

15 Sediment PCBs Concentrations Target = 2.5 parts per billion Current ambient = parts per billion Near-shore ambient = higher ?

16 TMDL Target(s) and Implementation Action Effort ($,time,…) Objective Target?

17 TMDL Adaptive Implementation (NAS, 2001)

18 Immediate actions High degree of certainty Fixed time period Monitoring program Assess progress toward targets Refine loading estimates Studies (experiment ?) and model refinement Validate key assumptions Determine long term actions Resolve key uncertainties ? Review targets, allocations, and implementation PCB TMDL Implementation


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