Napa Plant Site Desalting Modeling Data Comparison November 17, 2010 Agenda 1.Background 2.Approach to Salt Removal 3.2-D Modeling 4.Monitoring Data Comparison 1,460-acre site on Napa River floodplain DFG purchased land from Cargill Salt Co. March 14, 2003 (part of 16,500 acre transaction) Fits into DFG lands extending on both sides of river Background DFG Agreement included Cargill removal of residual salt in the plant to the extent possible to facilitate restoration Cargill has successfully harvested and removed approximately 350,000 tons (since 2003) Estimated 300,000 to 350,000 tons remain in the plant Pickle Ponds (Unit 3, B1, B2, B3) salt removed Residual salt remains in crystallizer beds with 2 to 6-inch salt crust Continued Harvesting not possible Cargill explored other ways to meet desalination obligation Background Approach to Salt Removal Other salt pond breach successes NSM Pond 4 NPS Ponds 9 and 10 - met RWQCB requirements within 24 hrs Develop breach concept to minimize impacts Field experiments to understand salt crust dissolution Redwood City Napa Plant Site Modeling to size breach for minimal impact 2-D Modeling Advection-Dispersion Model 2-Dimensional for internal Plant Site and Napa River 1-Dimensional for sloughs and external ponds Modeling Period (August-October 2000) Flow (USGS Gauging Stations at Oak Knoll Avenue and Agua Caliente) Tides (NOAA Tide Stations at Mare Island and mouth of Sonoma Creek) Ambient salinity (USGS Mare Island Causeway Station) Salt dissolution (Schaaf & Wheeler) 2-D Modeling Input Data Salt Mass Estimate BedsSalt Mass (tons) B1+B216,000 B332,000 Unit 332,000 Crystallizers240,000 Total320,000 Unit 3 B-2 B-3 B-1 Data Comparison Modeling Results - Salinity Monitoring locations limited circulation Higher ambient salinity Higher initial salinity peak Data generally in agreement Loc. A Loc. C Loc. B Modeling Results Location C Initial salinity increase higher, but within 3 weeks the data converges or monitored data is less 1.Confirm ambient salinity 2.Update salt mass estimate using monitoring data 3.Rerun model 4.Calibrate using dissolution rates Next Steps Questions? Comparison Results Inside South Unit Not corrected for ambient salinity difference Comparison Results At Breach Not corrected for ambient salinity difference Comparison Results At Breach Salinity Increase