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Former Chevron Station <br />301 West Kettleman Lane, Lodi - 2 - 13 July 2001 <br />identified in C -zone monitoring well MW -IOC at 7.5 micrograms per liter (µg/1) in March 2001, which <br />was the first sampling event for this well. Future monitoring will determine if additional investigation is <br />required south of MW -IOC in the C -zone aquifer. <br />Chevron Products Company (Chevron) operates an interim soil vapor extraction (SVE) and groundwater <br />extraction (GWE) system at the site to reduce soil and groundwater contamination and control plume <br />migration. In November 2000, Chevron added extraction well EX -3, which increased the groundwater <br />extraction rate to approximately 10 gpm. As of March 2001, 1.5 million gallons of contaminated <br />groundwater from the former Chevron site has been extracted, treated with carbon, and discharged to the <br />City of Lodi industrial sewer line. MtBE has decreased in on-site monitoring wells, and the GWE system <br />influent concentration has stabilized at approximately 2,000 µg/1. The GWE system appears to be <br />effectively stabilizing the on-site groundwater plume, and reducing groundwater contaminants. <br />Secor evaluated multiple remedial alternatives, and identified enhanced groundwater extraction and <br />treatment combined with the existing soil and groundwater remediation system as the most effective <br />method for soil and groundwater remediation at this site. Secor proposes to install two additional <br />groundwater extraction wells south of West Kettleman Lane to extend the radius of capture to all known <br />areas of impact. Secor estimates that the proposed extraction wells will be installed and connected for <br />operation by March 2002. Staff requests that Chevron continue all efforts to start operation of the <br />additional extraction wells as soon as possible. Staff believes that the proposed remedial approach is <br />appropriate and necessary to remediate soil and groundwater contamination at the former Chevron site. <br />Secor also negotiated with the City of Lodi to re -assign Lodi Municipal Well #12 (Well #12) to <br />emergency standby status. Under this designation, Well #12 will only be operated during emergency loss <br />of pressure in the water distribution system and for monthly water sampling. <br />With the submittal of the Addendum Report and your next quarterly progress report, you will have met <br />the requirements of the First and Second Notice of Violation letters, and will be in compliance with C&A <br />Order 5-00-704. During installation and connection of the groundwater extraction wells south of West <br />Kettleman Lane, active soil vapor extraction and groundwater extraction must be continued. The <br />groundwater extraction must continue to stabilize the groundwater plume and prevent movement of <br />MtBE toward City Well #12. If you have any questions or comments, please call me at (916) 255-3115. <br />M H ell <br />Associate Engineering Geologist <br />cc: Mr. Mark Owens, SWRCB, UST Cleanup Fund, Sacramento <br />Mr. Harlin Knoll, San Joaquin County Environmental Health Division, Stockton <br />Mr. David Evans, Secor International Incorporated, Sacramento <br />Mr. Frank Beeler, City of Lodi Water Department, Lodi <br />