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fjw <br /> - <br /> ENVIRONMENTAL, HEALTI�.�17EPARTMENT <br /> SAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> ?a Donna K.Heran,R.E.H.S. Carl Bor an,R.E.H.S. <br /> I <br /> Director <br /> 304 East Weber Avenue, Third Floor <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Mike Huggins,R.E.H.S.,R-RI. <br /> •Douglas W.Wilson,R.E.H.S. <br /> Program Manager <br /> Laurie A.Cotulla,R.E.H.S. Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> Fax: (209) 464-0138 Robert McClellon,R.E.H.s, <br /> Program Manager Mark Barcellos,R.E.H.S. <br /> A TEICHERT AND SON JUL 2 3 � <br /> GEORGE TAKEMORI <br /> P O BOX 15002 <br /> SACRAMENTO CA 95851 <br /> RE: 103 N. E Street SITE CODE- 1555 <br /> Stockton, CA 95205 <br /> Sari Joaquin County Environmental Health iDepartment (EHD) is the lead agency <br /> providing oversight for investigation and cleanup of releases from underground storage <br /> tanks (UST) within San Joaquin County. i In 1986, gasoline contamination was <br /> discovered in soil at the time of a UST. removal from the above referenced site. <br /> Monitoring wells (MWs) were installed in 1987 and groundwater contamination was <br /> documented. The groundwater.sample analytical results evidence TPH-gas and BTEX <br /> contamination. The site was placed in the EHD Local Oversight Program in 1989 for <br /> further site assessment and corrective action. <br /> In September 1987, contaminated soil was excavated to 35 feet below ground surface <br /> (bgs) from the former UST source area and .confirmation samples were collected for <br /> analysis. The excavated soil was treated on-site using land farming for aeration. <br /> Confirmation samples from the treated soil were collected and analyzed in 1988 to <br /> confirm treatment. <br /> By March 1994, 14 monitoring wells (MWs) had been installed to delineate the soil and <br /> groundwater plume. Soil vapor extraction and groundwater air sparing wells were <br /> installed after the investigation was completed. A soil vapor extraction pilot test <br /> conducted and by December 1994 a soil vapor extra ctionlground water air sparing <br /> system was installed and operating. The system operated until December 1995 when <br /> vapor concentrations declined and operation was no longer warranted. At that time, <br /> post remedial groundwater monitoring began and has continued to the present date. <br /> In September 1999, a boring (B-17) was completed to 95 feet bgs in the former source <br /> area to evaluate residual soil contamination -and further define the vertical extent of soil <br /> contamination. No high concentrations of TPH-gas, BTEX, or gasoline additives were <br /> evidenced in the soil analyzed from B-17, even though groundwater results from MWA3 <br /> and MW-14 in that area continued to indicate the presence of TPH-gas, BTEX and 1,2 <br /> DCA , <br /> iI <br /> P <br /> �I <br /> li <br />