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California Regional Water Quality Control Board <br />Central Valley Region j W ' <br />3 <br />Katherine Hart, Chair .L.��-` <br />Linda S. Adams 11020 Sun Center Drive #200. Rancho Cordova. California 95670-6114 Edmund G. Brown Jr. <br />Acting Secretary for Phone (916) 4843291 • FAX (916) 464-4645 Governor <br />Environmental Protection http://www.waterboards.ca.gov/centmlvalley <br />5 May 2011 <br />Ms. Jennifer Sedlachek <br />ExxonMobil Environmental Services Company <br />4096 Piedmont Ave, #194 <br />Oakland, CA 94611 <br />DOCUMENT REVIEW, FORMER MOBIL STATION 99CAS (AKA MARLER PROPERTY, <br />(AKA JH GRIFFIN MOBIL SERVICE), 75 EAST ALPINE AVENUE, STOCKTON, <br />SAN JOAQUIN COUNTY (CASE # 390857) <br />I reviewed the Addendum to Corrective Action Plan (CAP Addendum) received 4 May 2011 from your <br />consultant Cardno ERI. The CAP, approved one year ago, stated that soil vapor extraction (SVE) by <br />itself would be effective for mass reduction in unsaturated soil, but would not address groundwater <br />contamination or plume mobility. The CAP also stated dual phase extraction (DPE) for soil vapor, <br />shallow groundwater and liquid phase hydrocarbons (if present), in conjunction with SVE for select <br />wells, would be effective for soil and groundwater remediation, and was the recommended and <br />approved remedial alternative. The CAP Addendum requests a change from inclusion of DPE with <br />SVE to SVE and air sparging (SVE/AS), using the rationale that groundwater concentrations (although <br />orders of magnitude above water quality goals) have begun to show declining concentrations, <br />indicating that offsite migration control is no longer necessary; and that SVE/AS will adequately clean <br />up soil and groundwater in a reasonable time frame and will not require dewatering of the upper 35' of <br />the saturated zone, resulting in a more cost effective approach to remediation. The CAP Addendum <br />proposes six SVE/AS wells (AS/SVE-1 through AS/SVE-6) to be installed on an accelerated schedule, <br />with SVE./AS system startup by 1 August 2011. A work plan for the wells installation was included in <br />the CAP Addendum. <br />The CAP Addendum is approved. Please procure the necessary permits and notify the San Joaquin <br />County Environmental Health Department and myself at least three working days prior to start of <br />fieldwork. If you have any questions, you may contact me at (916) 464-4615, or by email at <br />jbarton@waterboards.ca.gov. <br />JAMES L. I_, BARTON, P.G. <br />Engineering Geologist <br />cc: Carmen Harms, SWRCB, UST Cleanup Fund, OSCA Account, Sacramento <br />Nuel Henderson, San Joaquin County Environmental Health Department, Stockton <br />Duane and Ms. Wendy Berdt, Guido Segarini Trust, PO Box 1810, Aptos 95001 <br />Theresa Marler, 14245 Lora Drive, #16, Los Gatos, CA 95030 <br />Arthur Lavagnino, 1466 W. Magill Ave., Fresno 93711 <br />Scott Conner, First Baptist Church of Stockton, 3535 N. EI Dorado St., Stockton 95204 <br />Matthew Herman, Cardno ERI, 601 N. McDowell Blvd., Petaluma 94954 <br />California Environmental Protection Agency <br />pf5Recycled Paper <br />