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4 <br /> Quik Stop Market No. 132 January 6, 1993 <br /> Project No. F7132.34 Page 5 <br /> u <br /> I <br /> I 5 <br /> ' SAMPLE ANALYSES <br /> All soil samples collected were analyzed for TPHG with benzene, toluene, ethyl <br /> benzene, and total xylenes (BTEX) distinction using modified Environmental Protection <br /> ' Agency (EPA) Method 5030/8015/8020. All groundwater samples were analyzed for <br /> TPHG with BTEX distinction using EPA Method 5030/8015/8020. In addition, <br /> groundwater samples collected from newly installed wells were analyzed for fecal <br /> coliform as required under S7CPHS Ordinance No. 1862. <br /> SUMMARY OF ANALYTICAL RESULTS <br /> Tabulated results for all laboratoryanalyses are resented in Tables 1 and 2. <br /> Y P <br /> Laboratory reports and chain-of-custody documents are included in Appendix F. <br /> ' <br /> Exploratory Boring Soil Samples <br /> Soil samples were analyzed for TPHG and BTEX. As shown in Table 1, TPHG and <br /> BTEX compounds were not detected in any of the soil samples analyzed. <br /> ' Groundwater Samples <br /> Groundwater samples were collected from the two newly installed wells and the three <br /> existing groundwater monitoring wells at this site sampled for quarterly monitoring. <br /> As can be seen in Table 2, TPHG or BTEX compounds were not detected in any of the <br /> samples except for MW-5 in which TPHG, toluene, ethylbenzene, and total xylenes <br /> were detected at concentrations of 350 ppb, 0.7 ppb, 0.6 ppb, and 0.7 ppb, respectively <br /> and in MW-2 in which benzene and toluene were detected at concentrations of 0.66 ppb <br /> and 1.1 ppb, respectively. Samples from MW-6 and MW-7 were analyzed for the <br /> presence of fecal coliform; none was detected. In addition, in MW-1R and MW-5, <br /> discrete peaks which elute before benzene were noted in the chromatogram (Appendix <br /> ' F). <br /> DISCUSSION AND RECOMMENDATIONS <br /> The soils observed during the drilling of MW-6 and MW-7 generally consisted of 3 to 4 <br /> feet of silty clay overlying 3 to 4 feet of sandy clays to clayey sands. These in turn <br /> ' were observed to overlay 2 to 3 feet of a clean sand which extended to a depth of 10 to <br /> 11 feet. Beneath this sand approximately 7 feet of silty clay was encountered and at <br /> approximately 18 to 20 feet saturated very sandy aquifer soils were encountered. The <br /> ' aquifer was found to be 3-1/2 to 4-1/2 feet thick overlying a silty to sandy clay <br /> aquitard. <br /> Soil sampling and logging of the boreholes and comparison with previous borehole logs <br /> suggest that the upper aquifer encountered beneath the Quik Stop Market extends to the <br /> other side of the adjacent Taco Bell site. Analysis of groundwater samples indicate that <br /> the petroleum hydrocarbon constituents detected in well MW-5, monitoring the upper <br />