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ENVIRON&EN <br /> TAL HEALTH SEPARTMENT <br /> °"'" SAN JOAQUIN COUNTY <br /> Program Coordinators <br /> Q - Donna K. Heran, R.E.H.S. <br /> 304 East Weber Avenue,Third Floor Carl Borgman,R.E.H.S. <br /> Director <br /> Laurie A. Cotulla,R.E.H.S. Stockton,California 95202-2708 Mike Huggins, R.E.H.S., R.D.I. <br /> L <br /> Margaret Lagorio, R.E.H.S. <br /> c4�iFORr'\P Assistant Director Telephone: (209)468-3420 Robert McClellon, R.E.H.S. <br /> Fax: (209)464-0138 .Teff Carruesco, R.E.H.S. <br /> Website:www.sjgov.org/ehd/ Kasey Foley, R.E.H.S. <br /> OCT 13 2006 <br /> DON RODGERS <br /> 11900 S UNION ROAD <br /> MANTECA CA 95336 <br /> RE: The Transmission Shop SITE CODE: 9321 <br /> 515 Charter Way <br /> Stockton CA 95206 <br /> San Joaquin County Environmental Health Department (SJC/EHD) has reviewed Report <br /> of Spring 2006 Site Investigation (Report) dated August 23, 2006, and Second Quarter <br /> 2006 Status Report(QMR) dated August 3, 2006, submitted on your behalf by Shaw <br /> Environmental, Inc. (Shaw) and has the following comments. <br /> The Report documents a field investigation conducted in March 2006 that utilized a direct <br /> push technology called Membrane Interface Probe (MIP). The purpose of this <br /> investigation was to define the vertical and lateral extent of the groundwater contamination <br /> at this site, and to determine the best way to remediate the contamination. The proposed <br /> depth of the MIP probes was 100 feet below surface grade (bsg). Prior work at this site <br /> had identified contamination in groundwater to 80 feet bsg (MW-4R-D) and in soil to 70 <br /> feet bsg (boring MW-4R-D). <br /> A total of 8 MIP borings were advanced across the site and in the roadway on the eastern <br /> side of the property. The maximum depth explored by the MIP borings was approximately <br /> 67 feet bsg (MIP-4). Reported readings from the MIP probe indicate significant <br /> contamination remains submerged at this site, from approximately 35-66 feet bsg. The <br /> only MIP probe to not detect significant contamination was MIP-7, towards the western <br /> side of the property. Soil samples for analysis were collected from four borings (DP-4, <br /> DP-6, DP-8 and DP-9), located near the corresponding MIP probes. Sample depths <br /> ranged from 25 to 69 feet bsg. Analytical results confirmed significant petroleum <br /> hydrocarbon contamination in each of the borings. <br /> The most significant information gained from this phase of work is that the soil vapor <br /> extraction (SVE) remediation that was previously conducted at this site appears to have <br /> been effective in reducing the soil contamination in the vadose zone. No new information <br /> was provided on the vertical extent of the contamination; the site remains vertically <br /> undefined. Site conditions that are considered impediments to remediation were <br /> discussed by Shaw in the report. Soil types to 40 feet bsg are mostly silty. Soil from 40- <br /> 60 feet bsg is mostly sandy and would be more amenable to remediation by either <br /> extraction or injection. <br />