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<br /> Ms.Linda Turkatte
<br /> August 22, I991
<br /> Page 3
<br /> installition orAdWflona[ 1lfonitnrin.Ivell
<br /> Monitoring well MW-10 was installed downgradient from the site to a depth of 45-feet below grade on
<br /> July 25, 1991 (Figure 2). Soil sample were collected at 5-foot intervals until ground water was
<br /> encountered at approximately 37 feet. Soils encountered consisted primarily of silts and clays to a depth
<br /> of approximately 33 feel, clayey sand from 33 to 43 feet,and sand below 43 feel. Soil boring, well
<br /> installation,well development,and sampling procedures are described in Enclosure A. A soil boring log
<br /> containing a description of the soils encountered and other pertinent information is included in
<br /> Enclosure C. Monitoring well specifications are included in Enclosure D.
<br /> Solt Sam !e Anal tical Results
<br /> Sail samples collected from depths of 30 and 35 feel below grade were submitted for chemical analysis
<br /> of BTEX and TPH as gasoline, Analytical test results indicate that petroleum hydrocarbon constituents
<br /> were'lot present at or above the limits of detection in these samples. The results of analytical testing
<br /> are summarized in Table 3,and copies of the certified laboratory reports are included in Enclosure E
<br /> Soil cuttings generated during drilling were stockpiled on site and covered with visqueen. Two soil
<br /> samples were collected from the stockpile on August 1, 1991. The samples were composited prior to
<br /> analysis for BTEX,TPH as gasoline,and CAA7 Metals. Analytical test results indicate that petroleum
<br /> hydrocarbon constituents were rot present at or above the limits of detection in the composite soil
<br /> sample. CAM Metals were present at concentrations typical of native soils. Copies of dic cerlified
<br /> laboratory test results are included in Enclosure F.
<br /> Ground Water Sam le Anol deal Results
<br /> A ground water sample collected from monitoring well MW-10 on August 1, 1991,was submitted for
<br /> BTEX and TPH as gasoline analysis. In addition, a ground water sample was collected for fecal
<br /> coliform analysis,as requested by the San Joa,iuin County Department of Health Services. Analytical
<br /> test results indicate that the sample collected from monitoring well MW-10 contained TPH as gasoline
<br /> at s waCentration of 69 ppb and benzene at a concentration of 2 6 ppb: Fecal coliform was not present
<br /> at or above the detection limit of 3.8 colony forming units per 100-milliliters. Ana1v ical test results for
<br /> BTEX and TPH as gasoline are summarized in Table 2,and copies of the certified laboratory reports
<br /> are included in Enclosure F.
<br /> Analytical lest results for the ground water sample collected from monitoring well MW-10,along with
<br /> ground water elevation data,suggest that downgradient transport of petroleum hydrocarfmn constituents
<br /> in ground water does not cmtcnd significantly further than the location of monitoring well MW-10. A
<br /> dissolved beitiene isoconixntratian map prepared from., rJuly 23,1991,ground water sampling results,
<br /> and the monitoring well MW-10 sampling results.-is included as Figure 4.r
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