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Mr. Robert Cochran - 2 - 12 August 2003 Chevron Environmental Management Company shut down the SVE system, due to asymptotic levels of treated contaminants and lack of rebound after SVE system shutdown. 2) I recommend that Chevron conduct computer modeling of the remaining contaminant mass in soil and groundwater, to determine the pumping rate necessary to maintain hydraulic control and protect City of Lodi Municipal Well #12 (Well #12), 420 feet southwest of extraction well EX -2. The modeling should consider various pumping rates (including no pumping) and locations. If soil and groundwater modeling show no impact to Well #12, then the GWE system may also be shut down. 3) Groundwater monitoring will continue after GWE system shutdown, to determine if rebound occurs. During the GWE rebound test, all monitoring wells will be sampled quarterly for at least one hydrologic cycle (one year). If little or no rebound occurs, then Chevron may submit a site closure report. 4) Quarterly groundwater monitoring is required by Regional Board Cleanup and Abatement Order No. 5-00-704. After the soil/groundwater modeling and GWE system rebound test (Comment 2) have been conducted and the report(s) have been reviewed by Regional Board staff, I recommend reconsidering Chevron's request to reduce groundwater monitoring, or consider a request for No Further Action Required at the site. 5) The California Registered Geologist listed on the signature page did not sign the Report, as required by the California Business and Professions Code. Submittal of a revised signature page signed by a California licensed professional engineer or geologist with license number/seal is necessary.