SITE INFORMATION AND CORRESPONDENCE_FILE 1

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s • • San Joaquin County °�'" Environmental Health Department �0._ DIRECTOR .CO Donna Heran, REHS Q: ^ 600 East Main Street �—� .� 7: < Stockton, California 95202-3029 PROGRAM COORDINATORS Robert McClellon, REHS Jeff Carruesco,REHS, RDI Website: www.sjgov.org/ehd Kasey Foley, REHS Phone: (209) 468-3420 Linda Turkatte, REHS Fax: (209) 464-0138 August 9, 2011 Denis L. Brown Hung Tran & Mary Nguyen Shell Oil Products US Pacific Avenue Shell Station 20945 S. Wilmington Blvd. 6131 Pacific Avenue Carson, CA 90810-1039 Stockton, CA 95207 Subject: Shell-Branded Service Station 6131 Pacific Avenue Stockton, CA 95207 The San Joaquin County Environmental Health Department (EHD) has reviewed the site file and correspondence history for the subject contaminated underground storage tank (UST) site and has the following comments. In August 2003, the EHD recommended you conduct interim remediation of the source area of the plume at your site. This is the area near the former UST's, and is the area with the highest concentrations of soil and groundwater contamination. In December 2003, the EHD agreed that there appears to be a solvent plume in the area southeast of your site and that offsite wells MW-8 through MW-11 represent a lateral non-detect line for the petroleum hydrocarbon plume emanating from your site. Groundwater monitoring wells MW-6 and MW-7, which are located between your onsite wells and wells MW-8 through MW-11 have historically reported high concentrations of petroleum hydrocarbon contamination including benzene, toluene, ethylbenzene, xylenes, and fuel oxygenates. These substances are not generally found in solvent plumes. In February 2004, the EHD approved a proposal to conduct interim remediation of the source area soil contamination by dual phase extraction (DPE). In January 2005, the EHD was notified by your consultant that a limited 5-day DPE Test had been conducted at the site. The EHD responded by reminding you and your consultant that a test had not been approved, but a continuous interim remediation was. You were directed to continue the interim DPE remediation system operation. In September 2005, the EHD approved a Corrective Action Plan (CAP), which included a proposal to have a contingency plan for remediation of groundwater contamination should DPE be not effective, and directed submittal of a work plan for the installation of additional DPE wells and implementation of the proposals presented in the CAP. In December 2005, the EHD approved a Remedial Action Plan (RAP) and installation of additional DPE wells. You were again directed to continue interim DPE remediation of the source area.