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s . <br />' ] Mr. Robert Cochran - 2 - 12 August 2003 <br />Chevron Environmental Management Company <br />T <br />shut down the SVE system, due to asymptotic levels of treated contaminants and lack of rebound after <br />SVE system shutdown. <br />.� 2) I recommend that Chevron conduct computer modeling of the remaining contaminant mass in soil and <br />groundwater, to determine the pumping rate necessary to maintain hydraulic control and protect <br />City of Lodi Municipal Well #12 (Well #12), 420 feet southwest of extraction well EX -2. The modeling <br />— should consider various pumping rates (including no pumping) and locations. If soil and groundwater <br />modeling show no impact to Well #I2, then the GWE system may also be shut down. <br />3) Groundwater monitoring will continue after GWE system shutdown, to determine if rebound occurs. <br />_ During the GWE rebound test, all monitoring wells will be sampled quarterly for at least one hydrologic <br />cycle (one year). if little or no rebound occurs, then Chevron may submit a site closure report. <br />4) Quarterly groundwater monitoring is required by Regional Board Cleanup and Abatement Order <br />] No. 5-00-704. After the soil/groundwater modeling and GWE system rebound test (Comment 2) have <br />been conducted and the report(s) have been reviewed by Regional ional Board staff, I recommend <br />, <br />., reconsidering Chevron's request to reduce groundwater monitoring, or consider a request for No Further <br />F � � <br />J Action Required at the site. <br />-- 5) The California Registered Geologist listed on the signature page did not sign the Report, as required <br />by the California Business and Professions Code. Submittal of a revised signature page signed by a <br />California licensed professional engineer or geologist with license number/seal is necessary. <br />D' <br />r' <br />— <br />r: <br />I <br />h <br />. l w <br />. F• <br />