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t • � <br /> 11 December 1991 <br /> GeoAudit CV45-49C5-1. 10 <br /> Page 3 of 3 <br /> samples were not transmitted for laboratory analysis, and <br /> ' excavation was continued. <br /> The lower 23 feet of the excavation consists of light-brown, fine- <br /> grained sand and clay. All samples collected for laboratory <br /> analysis came from this unit. <br /> CONCLUSIONS <br /> t1. Contamination at this site was restricted to the upper 33 feet <br /> of the soil profile. Groundwater is estimated to be 10 to 15 <br /> feet below the contamination and is not impacted. <br /> 2 . Contamination at this site was restricted to the western half <br /> ' of the original tank excavation. Since no contamination was <br /> detected in the eastern portion of the original excavation, no <br /> soil was removed from this area during the overexcavation. <br /> 3 . The primary contaminants at this site were gasoline, aromatic <br /> hydrocarbons (BTEX) , and lead. Samples collected at the time <br /> of tank removal had gasoline concentrations ranging from 13 .8 <br /> ' to 1717 mg/kg (ppm) . BTEX concentrations ranged from non- <br /> detect to 198. 6 ppm in those samples, and concentrations of <br /> lead reached 30 ppm. <br /> 4 . Final sampling performed on the north, south and west walls <br /> and the floor of the excavation has confirmed the successful <br /> removal of the contaminated soil. Concentrations of all <br /> ' hydrocarbon compounds in these samples are below detection <br /> limits. Leachable lead concentrations in these samples were <br /> less than 0. 1 ppm. <br /> ' 5. The excavated soil is non-hazardous according to DHS <br /> guidelines. <br /> ' RECOMMENDATIONS ' <br /> We recommend that you transmit a copy of this report to the San <br /> ' Joaquin County Environmental Health Division. Based on the results <br /> of sampling and laboratory analysis, we believe that the <br /> contamination has been successfully removed and that EHD will grant <br /> ' approval to transport the stockpiled soil to an approved disposal <br /> facility. This soil should be hauled by a properly licensed firm <br /> under non-hazardous manifest. <br /> We also recommend that you apply for permission to fill the <br /> excavation with clean fill material and resurface the excavated <br /> area. We recommend that you contact the San Joaquin EHD and request <br /> ' authorization for site closure. <br />