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ENVIRON idENTAL HEALTH YIEPARTMENT <br /> PpU1N SAN JOAQUIN COUNTY Program Coordinators <br /> Donna K. Heron, R.E.H.S. <br /> " <br /> Director 304 East Weber Avenue, Third Floor Carl Bergman, R.E.H.S. <br /> Laurie A. Cotulla, R.E.H.S. Stockton, California 95202-2708 Mike Huggins, R.E.H.S. , R.D.I. <br /> c'°Uko.A��" • Assistant Director Telephone: (209) 468-3420 Margaret Lagorio, R.E.H. S. <br /> Robert McClellon, R.E.H. S. <br /> Fax: (209) 464-0138 Jeff Carruesco, R.E.H.S . <br /> Website: www.sjgov.org/ehd/ Kasey Foley, R.E.H.S. <br /> R ELLIS JR ®CT 13 2006 <br /> ETHYL D ELLIS TRUSTEE ETAL <br /> 1991 W LINCOLN ROAD <br /> STOCKTON CA 95207 - 2462 <br /> RE: California Tank Lines, Inc . SITE CODE: 001095 <br /> 3105 South El Dorado Street <br /> Stockton, California 95206 <br /> San Joaquin County Environmental Health Department (EHD) has reviewed Work Plan <br /> Determination of the Extent of Contamination Affecting MW-4 dated August 1 , 2006, prepared by <br /> Environcering, Inc. (EI) on your behalf. By letter dated May 22, 2006, EHD noted the presence <br /> of high concentrations of chemicals of concern (COC) in groundwater samples collected from <br /> monitoring well MW-4 and directed further investigation to assess the lateral and vertical extent <br /> of impacted soil and groundwater at this site. On September 25, 2006, EI revised the work plan <br /> to include geological logging while advancing the borings, and resubmitted the work plan signed <br /> by a professional geologist licensed by the State of California. <br /> i <br /> In this work plan, EI proposes the advancement of three off-site direct push borings "to determine <br /> the vertical and lateral extent of contamination affecting MW-4." The proposed boreholes will be <br /> located approximately 60 feet northwest, 50 feet southeast, and 150 feet northeast of monitoring <br /> well MW-4. The following items addressed in the work plan need further clarification: <br /> • Will grab groundwater samples be collected at each borehole for analysis? <br /> i <br /> • Will a minimum of four soil samples be submitted for analysis from each borehole or <br /> E from the combined three boreholes? <br /> EHD approves the locations for two proposed soil borings to be advance approximately 60 feet <br /> northwest and 50 feet southeast of MW-4. However, it is not clear whether these borings will be <br /> advanced to a total depth of fifty feet below ground surface (bgs) or whether the total depth for <br /> each boring will be determined based on unspecified field measurements that demonstrate <br /> petroleum hydrocarbon contaminants are not present in two consecutive soil samples collected at <br /> five-foot intervals. What is apparent is that soil and groundwater samples collected at MW-4 are <br /> impacted at 50 feet bgs. This is based on high concentrations of COC detected in soil samples <br /> collected at 50 bgs during the installation of MW-4, and groundwater samples collected during <br /> the quarterly groundwater monitoring events from MW-4 screened between 27 and 50 feet bgs. <br /> EHD is concerned that if the total depths for these borings are limited to unspecified field <br /> measurements of soil samples collected at five-foot intervals, or to 50 feet bgs, this investigation <br /> will provide little additional information. Please clarify what field measurements will be applied <br /> to soil samples to determine total boring depths, and provide technical justification for proposing <br /> j boring depths of fifty feet bgs. <br />'r <br /> l <br />