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1' <br /> PUBLIC HEALTH SERVICtS <br /> SAN JOAQUIN COUNTY r <br /> ENVIRONMENTAL HEALTH DIVISION ` <br /> Karen Furst, M.D., M.P.H., Health Officer <br /> 304 East Weber Avenue, Third Floor • Stockton, CA 95202 gc�FORt� <br /> 209/468-3420 <br /> STEPHEN VALENTINE MAY 17 2000 <br /> STEVE & GENES SERVICE <br /> 6232 HEMET AVE <br /> STOCKTON CA 95207 <br /> RE: STEVE &GENES SERVICES SITE CODE: 2080 <br /> 2315 N EL DORADO ST <br /> STOCKTON CA 95204 <br /> San Joaquin County Public Health Services,Environmental Health Division (PHS/EHD) <br /> has reviewed Additional Soil and Crrw duaterImustigation(the work plan) dated April 11,2000 <br /> prepared by Geological Technics,Inc. (GTI). The work plan is not approved. <br /> Monitoring well 101 (NM 10 1) was installed in August 1999 at the above referenced site. <br /> MW-101 is screened from 92 to 97 feet below surface grade (bsg) and depth to fust <br /> groundwater is about 28 feet bsg. Analytical results of the quarterly groundwater samples <br /> from MW-101 were 74 parts per billion (ppb) of Benzene and 5,670 ppb of Total Petroleum <br /> Hydrocarbon as Gasoline (TPH g) in September 1999, and 7 ppb of Benzene and 867 ppb <br /> of TPH g in December 1999. Analytical results of the soil sample collected at approximately <br /> 70 feet bsg during the installation of MW-101 were 0.342 parts per million (ppm) of Benzene <br /> and 44 ppm of TPH g. Analytical results of the soil sample collected at 95 feet bsg from soil <br /> boring 201 (SB-201) were 185 ppm of Benzene and 26 ppm of TPH G,and at 111 feet bsg <br /> were 0.33 ppm of Benzene and 4 ppm of TPH g. <br /> Based on the above results,PHS/EHD directed additional work to investigate the vertical <br /> extent of the contamination in both soil and groundwater in a letter dated February 16,2000. <br /> PHS/EHD also recommended using cone penetration technology to characterize the <br /> geology and also to better control against cross-contamination in sampling. <br /> PHS/EHD disagrees with the work plan's proposal to advance 10 Geoprobe borings to 30 <br /> feet bsg. The depth of 30 feet bsg is insufficient in the investigation of the lateral extent of <br /> the contamination since data exist indicating the presence of hydrocarbon petroleum <br /> contamination in the vadose zone on site to at least 52 feet bsg. Analytical results of the soil <br /> samples collected from boring#5 which was converted to monitoring well# 1 (MW 1) were <br /> 640 ppm of TPH g at 52 feet bsg and 29 ppm of TPH g at 56 feet bsg. Groundwater was <br /> not encountered until approximately 60 feet bsg when SB-5/MW 1 was advanced and the <br /> samples were collected in September 1994 (Inte)im Report and Results of Grwiduaterinzatigition <br /> dated October 19994 prepared by Wm J. Hunter&Associates). The depths of the <br /> exploration borings in an investigation of the lateral extent of the contamination should be <br /> dictated by the vertical extent of the plume,understanding of the geology and <br /> A T)ivicinn nF San 1--;n C'nimfv F--Ifl, CaTP SPTVICPC <br />