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%..r ..,r <br /> 0 <br /> v` Eonao G.BRo+aN Ja. <br /> earemen <br /> eatreaa • rA&mm Roomo z <br /> Water Boards , <br /> eMnRaea�rK rnoracnaM <br /> Central Valley Regional Water Quality Control Board <br /> 18 September 2012 <br /> Leon Marineau Chris L'Orange <br /> Cascades Inc. Drinker Biddle & Reath LLP <br /> 471 Marie-Victorin 50 Fremont Street <br /> Kingsey Falls, Quebec, Canada JOA 180 San Francisco, CA 94105 <br /> DOCUMENT REVIEW, DUPACO, INC., 800 WEST CHURCH STREET, STOCKTON, <br /> SAN JOAQUIN COUNTY, REGIONAL BOARD CASE 391187 <br /> 1 reviewed the Preliminary Data Evaluation Report and Recommendations for <br /> Monitoring Wells (Report) received 11 September 2012 from Geosyntec Consultants, <br /> the consultant for Dopaco, Inc. The Report provides a land survey of the Dopaco Inc. <br /> toluene area, marking of Global Positioning System (GPS) coordinates for the sample <br /> locations in Figure 2, boring logs, and the results and recommendations of an initial <br /> investigation to determine the distribution of toluene in soil and groundwater conducted <br /> as a prelude to installing four groundwater monitoring wells. My letter dated <br /> 10 July 2012 approved a work plan that included submittal of the Report, and also <br /> included sampling of the monitoring wells, and submittal of a report of the groundwater <br /> investigation with recommendations for follow-up work and a groundwater monitoring <br /> program. <br /> The Report details the membrane interface probe (MIP) screening that was conducted <br /> with the cone penetrometer testing (CPT) investigation. Eighteen (18) CPT borings <br /> (CPT-MIP-2012-1 through CPT-MIP-2012-18) were advanced near and around the <br /> former Dopaco, Inc. underground storage tanks (USTs) to a maximum depth of 45' <br /> below ground surface (bgs) to determine soil and engineering characteristics, and to <br /> determine adjacent CPT locations for up to two (2) grab groundwater samples per <br /> boring. The MIP sensors attached above the CPT tool included a halogen specific <br /> detector (XSD), a photoionization detector (PID), an electron capture detector (ECD) , <br /> and a flame ionization detector (FID) to give a depth discreet distribution of volatile <br /> organic compounds (VOCs), including toluene. While the MIP goal was to map the <br /> relative distribution of VOCs, the grab groundwater sample results at CPT-2012-13 by <br /> USEPA Method 8260B for VOCs exceeded the MIP results of no detected VOCs at MIP <br /> detection limit of one part per million (ppm). The remaining CPTs toluene groundwater <br /> results were below 1 ppm. Low levels of chlorinated solvents (excluding high levels of <br /> VOCs detected in CPT-MIP-2012-13) were also reported across the site. <br /> Kwn.E. Lamf er SeD,P.E.,cKmR I PAIAeuAL Q.OFAMWN P.E.,MEE,E]rEGrrMe WMER <br /> I I=Sun C—Mm D&m#M Renaho Caedow CA QWM I vrYrw.w&%wbowda.o&gwdcarftW9aff4V <br /> Q Mcm.50 P"FR <br />