Outline 1 2 3 4 Brief overview of

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

Multibox PCB Model CFWG Meeting September 15, 2005

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

PCBs in shallow sediments Version 2. 0 b

PCBs in channel sediments Version 2. 0 b

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

Next Steps for Model Development

Recommendations from independent testing: • Documentation is outdated – Provide documentation sufficient to proceed with testing without creating an extra report.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

Recommendations from independent testing: • 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: • 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

Estimated Timeline Create documentation 3 -4 days Review/modify input data 2 -3 days Elevated SSC in LSB 2 -3 days Adjust spin-up period 4 -5 days ** Additional congeners 2 days Improve hindcast (calibration) 5+ days ** Total: 18 -22 days 10 -12 days Red indicates steps ‘critical’ to continue with testing

Uncertainty Testing