1. Outline 1.Brief overview of multibox model (John) 2.Results of independent testing (Katherine) 3.Next steps for development (?)(John) 4.Overview of planned uncertainty testing (Tom)

2. Multibox PCB Model CFWG Meeting September 15, 2005

3. Multibox ? –50 Model Boxes –2 Vertical Layers –100 cm of sediments Physics Forced by: –Tides at Golden Gate –Delta Outflow –Local Tributaries –Wind, Rain

4. PCBs in shallow sedimentsVersion 2.0b

5. PCBs in channel sediments Version 2.0b

8. Independent Testing of SFEIs Multi-box Model for PCB Fate and Transport Prepared by Tetra Tech, Inc. Lafayette, CA September 15, 2005

9. Next Steps for Model Development

10. Recommendations from independent testing: Documentation is outdated –Provide documentation sufficient to proceed with testing without creating an extra report. Include updating equations from draft report Eventually document everything in a draft technical report Review and modify historic input data –Data are available, easy to update inputs Add variability to forecast data –Investigate applicability of alternative methods for generation of forecast inputs Investigate sea level rise –Interesting question, out of the scope of this project

11. Investigate impact of elevated SSC in Lower South Bay on PCB transport –Contribution to PCB mass transport is likely small, though an investigation is warranted –Prefer to leave sediment model development to Schoellhamer et al. Evaluate spin-up period. Investigate alternative initialization. –Significant consequences for PCB transport –Artifact of sediment model calibration –Lack data to change PCB initial conditions Include additional congeners –Yes Recommendations from independent testing:

12. Can Model / Data comparison be improved? –How good does hindcast need to be? –Probabilistic comparison may be useful –Loading function may be cause of overestimate Calibration (of loading curve?) Loading Curve Recommendations from independent testing:

13. Estimated Timeline Create documentation3-4 days Review/modify input data2-3 days Elevated SSC in LSB2-3 days Adjust spin-up period4-5 days ** Additional congeners2 days Improve hindcast (calibration)5+ days ** Total:18-22 days 10-12 days Red indicates steps critical to continue with testing

14. Uncertainty Testing