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ENVIRONMENTAL HEALTHNEPARTMENT <br /> �P°U'" � SAN JOAQUIN COUNTY <br /> _10O <br /> ' ��,�,°y Unit Supervisors <br /> Donna K.Heron,R.E.H.S. Carl Bor an,R.E.H.S. <br /> Director 304 East Weber Avenue, Third Floor � <br /> Mike Huggins,R.E.H.S.,R.D.I. <br /> AI Olsen, <br /> R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. <br /> c . �--r • Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> 1 r_-6 R. Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S. <br /> Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. <br /> KAREN PETRYNA <br /> EQUIVA SERVICES LLC <br /> PO BOX 7869 <br /> BURBANK CA 91501-7869 <br /> AUG 1 2 2003 <br /> RE: Shell Service Station SITE CODE: 1223 <br /> 6131 Pacific Avenue <br /> Stockton CA 95207 <br /> San Joaquin County Environmental Health Department (SJC/EHD) has reviewed the file <br /> for the above referenced site, and the "First Quarter 2003 Groundwater Monitoring <br /> Report and Sample Frequency Reduction Request' (Report) dated July 1, 2003 that was <br /> submitted on your behalf by Cambria Environmental Technology, Inc, and has the <br /> following comments. <br /> In September 1999 and again in December 1999, SJC/EHD requested a work plan be <br /> submitted to complete the contaminant definition at this site. A work plan was submitted <br /> January 31, 2000, and approved March 13, 2000. In May 2000, two cone penetrometer <br /> test borings were advanced on site to investigate the vertical extent of contamination. <br /> Impacted groundwater was encountered on site from grab samples collected at depths <br /> of 97 feet below surface grade (bsg) in both CPT borings; the vertical extent of impacted <br /> groundwater has therefore not been delineated. In November 2001 and in August 2002, <br /> a total of four additional monitoring wells, MW-8, MW-9, MW-10 and MWA 1, were <br /> installed to investigate the lateral extent of the shallow groundwater contamination. <br /> Results from implementation of the January 31, 2000 work plan indicate that the lateral <br /> and vertical extent of the groundwater contamination resulting from the unauthorized <br /> release at this site remains undefined. <br /> SJC/EHD is concerned with the slowness with which this investigation has proceeded. <br /> The unauthorized release report for this site was submitted in March 1990; official <br /> notification that the site was included in the State Water Board UST Pilot Program for <br /> assessment and clean up activities was made to Shell Oil Company in June 1990. <br /> Thirteen years have passed, and the site's groundwater plume is not defined or <br /> remediated. Groundwater contamination at the apparent core of the plume, near well <br /> VEW-2, was recently reported at concentrations of 68,000 micrograms per liter (pg/I) <br /> TPHg, and 1,200 lug/I benzene. SJC/EHD recommends that interim remediation of the <br /> core contamination, in both soil and groundwater, be initiated. Control and remediation <br /> of the onsite contamination will reduce the offsite migration of the plume, and therefore <br /> will also reduce the long-term cost of the entire remediation. <br /> The Report recommends discontinuing monitoring and sampling of wells MW-8, MW-9, <br /> MW-10 and MW-11, stating that the analytical data and chromatograms show that the <br /> total petroleum hydrocarbons (TPH) as gasoline reported in them was mostly <br /> tetrachloroethene (PCE), that there has never been PCE in wells on the subject site, and <br />