Laserfiche WebLink
LEEOSHILL HERKENHOFF, INC <br /> FINDINGS AND CONCLUSIONS <br /> Based on LH's Preliminary Site Assessment of the former underground tank site <br /> at 102 South Wilson Way in Stockton, the following conclusions can be made: <br /> 1 The geologic formation beneath the site is primarily composed of <br /> intermittent clay and sand layers. The water bearing zone appears to be <br /> a sand layer located beneath the silt. The water surface elevation was <br /> measured at approximately 53 feet below the ground surface in December of <br /> 1989. <br /> 2 Based on the observed water surface elevations, groundwater flow appears <br /> to be in approximately an easterly direction across the site. <br /> 3. Approximately 14 municipal water wells are located within a one mile radius <br /> of the site. Of these, only 3 wells appear to be down gradient of the <br /> site, the closest well being approximately 1300 feet down gradient. Water <br /> quality records show no evidence of petroleum hydrocarbon contamination <br /> to these municipal water wells. <br /> 4 Groundwater samples collected from MWI, MW3 and MW4 show trace <br /> concentrations of BTX&E and TPH as gasoline. <br /> 5. Groundwater samples collected from MW2 and MW5 contained relativel high <br /> concentrations of dissolved BTX&E and TPH as gasoline No phase separated <br /> petroleum hydrocarbons were observed. <br /> 6 Soil samples obtained from TB6, TB7, TB8, TB9, MW4 and MW5 indicate trace <br /> or non-detectable concentrations of BTX&E and TPH as gasoline, orders of <br /> magnitude below the allowable LUFT Manual guidelines for residual petroleum <br /> hydrocarbons. <br /> 7. Soil samples collected from TB5 indicate levels of BTX&E and TPH as <br /> gasoline in excess of the LUFT Manual guidelines. This suggests a soil <br /> concern in the northwest corner of the site. <br /> 8. Soil samples collected from the excavated soil stockpile and drum samples <br /> taken from BCA drums BC1, BC2, BC3, BC5, BC6, BC7, BC8 and BC9 indicate <br /> trace concentrations of BTX&E and TPH as gasoline orders of magnitude below <br /> the LUFT Manual guidelines. According to the leaching potential analysis <br /> and the general risk appraisal , using this soil as backfill in the open <br /> excavation would be acceptable. <br /> -26- <br />