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. ✓ `►O <br /> San Joaquin County <br /> A° " Environmental Health Department <br /> DIRECTOR <br /> �O BOG Donna Heran,REHS <br /> 600 East Main Street <br /> PROGRAM COORDINATORS <br /> Stockton, California 95202-3029 Margaret Lagorio,REHS <br /> Robert McClellon,REHS <br /> Website: www.sjgov.org/ehd <br /> Jeff Carruesco,REHS,RDI <br /> q�/FORS Kasey Foley,REHS <br /> Phone: (209)468-3420 <br /> Fax: (209)464-0138 <br /> October 22, 2009 <br /> Mr. John Johnson <br /> Former Cheaper Store Number 37 <br /> 765 Eubanks Drive, Suite D <br /> Vacaville, California 95688 <br /> Subject: Former Cheaper Store Number 37 <br /> 15 East Grant Line Road <br /> Tracy, California 95376-2720 <br /> By letter dated June 22, 2009, the San Joaquin County Environmental Health Department <br /> (EHD) recommended that grab groundwater samples be collected to delineate the vertical <br /> and lateral extent of the dissolved petroleum hydrocarbon plume at the above-referenced <br /> site. In response, ATC Associates Inc. (ATC) prepared Revised Work Plan to Evaluate <br /> the Lateral and Vertical Extent of Impacted Soil and Groundwater, dated August 10, 2009, <br /> and submitted the work plan to GeoTracker. <br /> In the work plan, ATC proposes to advance two borings to first groundwater at <br /> approximately eight-and-a-half feet below surface grade (bsg) to evaluate the lateral <br /> extent of impacted soil and groundwater. One proposed boring will be advanced in the <br /> sidewalk on the west side of Holly Drive, approximately fifty-five and sixty-five feet west of <br /> monitoring wells MW-5 and MW-8, respectively. During the most recent sampling event <br /> on September 8, 2009, methyl tertiary-butyl ether (MTBE) was the only contaminant <br /> detected in groundwater collected from MW-5 and MW-8, at concentrations of 7.3 and 2 <br /> micrograms per liter, respectively. Based on these low contaminant concentrations, and <br /> the distance this proposed boring is from the source area, the EHD does not approve the <br /> advancement of this off-site boring. <br /> The EHD does approve the advancement of the proposed boring to first groundwater at <br /> the northwest boundaries of this site for lateral delineation of the groundwater plume <br /> northwest of the source area. ATC proposes to collect soil for lithologic evaluation; and <br /> based on visual observation and readings taken from the photo-ionization detector, <br /> estimates that approximately one grab groundwater and two soil samples will be collected <br /> for laboratory analysis. <br /> ATC proposes to advance one boring to approximately eighty feet bsg between MW-5 and <br /> cone penetration test (CPT) boring CPT-2 to further evaluate the vertical extent of <br /> impacted groundwater beneath the site. ATC estimates that a minimum of two discreet <br />