SITE INFORMATION AND CORRESPONDENCE FILE 2

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Steve and Genes Service Page 2 of 2 y EHD directs the following to be conducted or submitted by December 1, 2007: • Provide a model of impacted soil demonstrating adequacy of current information for plume delineation or justification for any additional work for remediation or site investigation if needed. The model should include a set of cross sections with at least one longitudinal along the inferred plume axis and 2 or 3 transverse to the plume axis showing lithology and contaminant concentrations between Castle Motors and the Shell site. • Monitoring wells MW-207. and MW-209 provide vertical delineation of impacted groundwater in their areas, but MW-208 does not. Start sampling well MW-308 or install a new a well. Note: During a telephone conversation with GTI on May 17, 2007, the lack of sampling of MW-307, MW-308, and MW-309 was discussed. The lack of sampling was attributed to twisting and curving of the CMT well casing making it difficult to sample. If the water level is higher in the well than the screen interval,purging water at shallow depth may draw a fresh water sample up to where it can be collected. • Report all peaks detected by EPA Method 8260B analysis for all groundwater samples for two quarters. • Submit a workplan to continue the lateral characterization and assessment of impacted groundwater in the significant sand unit(s), especially in the down-gradient direction and toward the south and southeast. • Submit an evaluation of the vapor intrusion potential for the adjacent residential units. Please feel free to contact Frank Girardi at(209) 953-7868 if you have any questions. Donna Heran,REHS,Director Environmental Health Department Frank Girardi, Senior REHS Nuel C. Henderson,Jr., PG LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV cc: CRWQCB, Central Valley Region—James.L.L. Barton cc: Geological Technics,Inc. -Raynold I. Kablanow