SITE INFORMATION AND CORRESPONDENCE FILE 2

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San Joaquin County .� Environmental Health Department DIRECTOR Donna Heran,REHS Q 2� 1868 East Hazelton Avenue Stockton, California 95205-6232 PROGRAM COORDINATORS �. { Robert McClellon,REHS • Jeff Carruesco,RENS,RDI cq•• �P Website: www.sjgov.org/ehd Kasey Foley,REHS ��k o•Ra Linda Turkatte,REHS Phone: (209) 468-3420 Fax: (209)464-0138 September 19, 2012 Mr. Daryl J. Pessler Chevron Environmental Management Company Marketing Business Unit 145 South State College Boulevard, Suite 400 Brea, California 92821 Subject: Former Chevron Service Station 9-0557 139 South Center Street Stockton, California Dear Mr. Pessler: The San Joaquin County Environmental Health Department (EHD) has reviewed Site Assessment Report (SAR), dated 24 January 2012, and Semi-Annual Groundwater Monitoring Report, First Quarter 2012, (first semi-annual 2012 report), dated 06 March 2012, both submitted by your consulting firm, Holguin, Fahan & Associates, Inc. (HFA), on your behalf. In the SAR, HFA presented findings from advancing four cone penetration test (CPT) borings (CPT-7 through CPT-10) for lithological evaluation, and chemical analyses of soil and grab groundwater samples collected from borings advanced adjacent to each CPT borehole. In the first semi-annual 2012 report, HFA presented results from collecting groundwater samples from monitoring wells MW-3, MW-15, MW-15D and MW-18D2. In both reports, HFA concluded that the data illustrated that the lateral and vertical extents of petroleum hydrocarbon contamination have been delineated, the contaminant plume is well defined and shrinking, and further assessment of this site is not warranted. Although a significant amount of sorbed and dissolved total petroleum hydrocarbons as gasoline (TPH-g) remains at your site, only groundwater collected from monitoring wells MW-15, MW-15D and MW-18D2 appears to be impacted; and concentrations of contaminants of concern appear to be stable in groundwater collected from all three wells. Based on soil and groundwater analytical results presented in the SAR and first semi-annual 2012 report, the EHD is of the opinion that site remediation is warranted to reduce the contaminant mass in the former first-generation underground storage tank (UST) area; however, the State Water Quality Control Board (SWQCB) Cleanup Fund (CUF) has recommended this site be considered for closure. To this end, the EHD directs that a site closure report be submitted to this department that: 0 Provides an estimate when groundwater will return to water quality objectives;