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l e Ms. Linda Turkalte August 22, 1991 Page 3 Insta!iutlon o1 AddlNcnul A9nnttnrtna Well Monitoring well MW-1U was installed downgradicnt from the site to a depth of 45-feet below grade on July 25, 1991 (Figure 2), Soil samples were collected al 5-foot intervals until ground water was encountered at approximately 37 feet. Solis encountered consisted primarily of silts and clay to a depth of approximately 33 feet, clayey sand from 33 to 43 feet,and sand below 43 feet. Soil boring, well installation,well dev_lopmont,and sampling procedures are describe!in Enclosure A. A soil boring log containing a dcsc iption of the soils encountered and other pertinent information is included in Enclosure G Monitoring Well specifications are included in Enclosure D. Soil Sample Anat ical Resreits ScH tramples collected from depths of 30 and 35 feet below grade were submitted for chemical analysis of BTEX and TPH as gasoline. Analytical test results indicate that pelraleum hydrocarbon constituents were not present at or above the limits of detection in these samples. The results of analYlical testing are summarized in Table 3,and copies of the certified labor;tory reports are included in Enclosure E. Soil cuttings generated during .frilling were stockpiled on site and covered with visqueen. '1yo soil samples were collected from the stockpile on August 1, 1991. The samples were composited prior to analysis for BTEX,TPH as gasoline,and CAM Metals. Analytical test results indicate that petroleum hydrocarbon constituents were not present at or above the limits of detection in the composite soil sample. CAM Metals were present at concentrations typical of native soils. Copies of the certified x laboratory test results are included in Enclosure F. Ground Water Sam 1e Ana tient Results A g-ound water sample collected from monitoring well MW-10 on August 1, 1491,was submitted for BTEX and TPH as gasoline analysis. In addition, a ground water sample was collected for fecal coliform analysis,as requested by the San Joaquin County Department of Health Services. Analytical test results indicate that the sample colt-,ctcd from monitoring well NiW-10-contained-TPH as gasoline. at®W&Pentration of 69 ppb and benzene at a concentration of 2.6 ppb: Fecal col,,orm was not present at or above the detection limit of 3.8 colony forming units per 100-milliliters. Anaiyjical test results for BTEX and TPH as gasoline arc summarized in Table 2,and copies of the certified laboratory reports are included in Enclosure F. Analytical test results for the ground water sample collected from monitoring well MW-10,along with ground wafer elevation data,sugge:sl that dowugradieat Wnspoftafpe truleam.hydtacarboa.ranati.�uerls in ground water docs not extend significantly further than the location of monitoring,wall MW-19 A. dimalml hcttid66 lsdconcentrailon mapprepared from the July.a3,,1491,ground water sampling resells and 00,B300oring well M*10 sampling,resultseii included as Figure,4.