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ENVIRONMENTAL HEALTH DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> Donna a K.Heran,R.E.H.S. 304 East Weber Avenue, Third Floor ' cart Eorgman,R.E.H.S. <br /> Director <br /> Mike Huggins,R.E.H.S.,R.D.I. <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Douglas W.Wilson,R.E.H.S. <br /> • cq .NSP• Program Manager Telephone: (209) 468-3420 Margaret Lagorio,R.E.H.S. <br /> ttFoa Laurie A.Cotulla,R.E.H.S. <br /> Fax: (209) 464-0138 Robert McClellon, <br /> Program Manager Mark Barcellos,R.E.H.S. <br /> KEN GILLIES SEP 2 4 2002 <br /> GILLIES TRUCKING <br /> P O BOX 8303 <br /> STOCKTON CA 95208 <br /> RE: Gillies Trucking SITE CODE: 1703 <br /> 3931 Newton Road RO: 0264 <br /> Stockton, CA 95205 <br /> San Joaquin County Environmental Health Department (EHD) has received and <br /> reviewed Second Quarter 2002 Report, dated 25 June 2002, and <br /> correspondence dated 10 September 2002, prepared by your consultant <br /> Upgradient Environmental Consultants (UEC). Briefly, UEC concluded in the <br /> quarterly report that: <br /> • The principal contaminant of concern is diesel fuel, with maximum soil <br /> concentrations ranging from 10,000 to 20,000 parts per million (ppm) and <br /> maximum dissolved concentrations ranging from 50,000 to 200,000 parts <br /> per billion (ppb). The maximum dissolved methyl tert-butyl ether (MTBE) <br /> concentration detected has been 8 ppb and the maximum dissolved <br /> benzene concentration detected has not exceeded 20 ppb. <br /> • An estimated 7,000 cubic yards of contaminated soil was estimated to be <br /> in place following excavation to 35 feet below surface grade (bsg) and <br /> extends to 70 feet bsg in the former UST area. UEC postulates that diesel <br /> fuel migrated downward through permeable channel fill until encountering <br /> impermeable silt and clay and that the hydrocarbons became bound in the <br /> sediments above and below the contact between the two deposits. <br /> • Few options for remediation of this soil are available. Soil vapor extraction <br /> and natural attenuation are not thought to be effective for the diesel, of <br /> which 30 to 50 %(?) is hypothesized to be locked up in impermeable silt <br /> and clay. UEC opines that relatively low health risks posed by <br /> contaminants at the depths of occurrence do not warrant expenditure of <br /> considerable (unspecified) sums of money to remediate. <br /> • Dissolved contaminant concentrations fluctuate in response to ground <br /> water elevation changes. <br /> • Active remediation is too difficult to implement at the site as the most <br /> intensely impacted ground water is within the identified Modesto Channel <br /> and has a small volume. <br />