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_ r s— maMP <br /> x <br /> GS <br /> ¢� s <br /> Color Spot, Inc. D <br /> February 14, 1990 (88168C) 5 <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> f.' <br /> SOIL CONTAMINATION <br /> Based on field observations and laboratory analytical results, it is <br /> our opinion that soil contamination at the site has been remediated in accord <br /> ance <br /> With SJLHD requirements. Confirmatory samples collected from the base and walls <br /> of the resulting excavation indicate that toluene and xylenes exist in trace <br /> k amounts, well below DOHS ,applied action levels. SGD had an additional five <br /> feet <br /> of material laterally owerexcavated to insure contaminated material had been <br /> successfully removed. It is uur opinion that the trace amounts of the two l <br /> compounds represent ambient concentrations found throughout the area, or <br /> will naturally degrade by natural biodegradation in a short time. <br /> SGD recommends that no additional material be removed from the <br /> r r excavation and that the remaining stockpiled clean soil (Figure 3) be used as <br /> backfill mazeriaZ. We recommend that the existing excavation be backfilled and <br /> compacted with clean fill material per the San Joaquin County Grading Require- <br /> ments. <br /> ri »�! GROUND WATER CONTAMINATION <br /> In a January 17, 1990, letter SJLHD required that a survey of all <br /> ground water wells within a 2,000-foot radius be conducted, and that confirmation <br /> <a samples be collected from all ground water wells within a 500-foot radius of the <br /> site. <br /> SGD obtained copies of the.Well Driller Reports .for all knofm wells / <br /> within a;2 000-foot:radius of the .'site'from the California State <br /> Water Resources,•and submitted these data directly to:Ms. Darlene Reuss gof SJLHDrtment . <br /> ti = <br /> o Thee reports contain details of well construction, screened intervals, total <br /> ' depths,.. and depth to ground water. .' <br /> i. <br /> # Four irrigation/domestic ground water wells are located within a 500- <br /> } foot -radius of the site and were ssfmpled as per SJLHD requirements. 1,11 four <br /> { <br /> wells contained trace amounts of benzene and three contained trace amounts of <br /> _ toluene, Both constituents ,were present in concentrations well below the f <br /> t�s applicable State of California Drinking Water.--Standards.— <br /> Based on the fact that benzene was found in the ground water samples, <br /> but not in the confirmatory soil samples collected from the excavation, itis our � . <br /> S opinion the ground water contamination has been caused by a source other than the <br /> site. Several of the wells containing benzene are located u <br /> pgradient of the <br /> site. The believed upgradient UST site located at 5401 East Harney Lane which { <br /> L <br /> k` <br />