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22 September 1997 <br /> AGE-NC Project No 95-0167 <br />' Page 5 of 6 <br /> ' summarized in Table 2 -Analytical Results of Grab Water Samples The laboratory reports (MAI <br /> Laboratory ID 56586, 75754 to 7575$), QA/QC reports and chain-of-custody forms are Included in <br /> Appendix B <br /> ' 5.0. SUMMARY AND CONCLUSIONS <br /> The following conclusions were drawn from the results of this investigation <br /> • Ground water at the site was encountered at a depth of approximately 25 feet bsg in <br /> September 1995 and at a depth of 15 feet bsg in April 1997 The prevailing ground water <br /> flow direction in this area of Stockton is generally toward the northeast, based on ground <br /> water flow direction observed on other sites in the vicinity <br /> • The most intensely hydrocarbon-impacted soil was encountered in the area of the former <br /> ' dispenser The highest concentration of TPH-g was detected in soil samples collected from <br /> beneath the former dispenser area TPH-g was detected at 230 ppm at a depth of ten feet bsg <br /> in boring P3 Soil contamination was limited to the area of borings P2 P3, and P7 and was <br /> not present in boring P5 and P6 TPH-g concentrations at 8 3 ppm, encountered in boring P7 <br /> under the building at the site, limits the extent of the severely impacted soil to the area <br /> ' directly beneath the former dispenser <br /> • Adequate chemical parameters for bio-remediation are present in the soil at the site Natural <br /> ' attenuation utilizing passive bio-remediation may not be a viable soil remediation alternative <br /> for the site due to the potential presence of a bio-toxin effect in the area of the petroleum <br /> release <br /> ' The highest concentration of dissolved hydrocarbons quantified as TPH-g and overall <br /> BTE&X compounds are distributed in the area east of the former UST and dispenser <br /> locations near P6 Hydrocarbons were encountered in a down-gradient direction from the <br /> ' former dispenser, at the location of boring P5 and further down-gradient at the location of <br /> boring P 1 Based on the data from the grab water sampled collected from boring P7, TPH-g <br /> ' concentrations in ground water decrease westward of the former fuel dispenser, under the <br /> building on the site <br /> • The estimated lateral extent of dissolved TPH-g is depicted in Figure 4 - Dissolved <br /> ' - Hydrocarbon�Concentrataons Due to the increased measures ground water elevation at the <br /> site the location of boring P1 is likely within the dissolved hydrocarbon plume <br /> Advanced GcoEm ironmental,Inc <br /> t <br /> e <br />