ARCHIVED REPORTS XR0012749 - Laserfiche WebLink

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Conclusions and Recommendations After analysis of the results of the JHK and BC investigations, the following conclusions and recommendations have been made: I- Soils in the area of the wormer tank locations have _ detectable levels o; hydrocarbons. Three of the samples, GL-2B (7. 5 to 8.0 feet) , GL-2C (9. 0 to 9.5 feet) , and GL-3B the gasoline (10.0 to 10.5 feet) from the area of tank excavations have Tpu levels of 240 mg/kg, 200 mg/kg, and 110 mg/kg, respectively. The three samples were from' backfill material in the area of the former gasoline storage tanks . This is not an indication that the gasoline tanks were .leaking, Oxlly that the backfill material contained hydrocarbons. Soil samples from 72.0 to 12.5 feetand 15.0 to 15.5 feet in test hole GL-2 and 20.0 to 20.5 feet in GL-3 had no deL*ectabie hydrocarbon levels. These samples were from native soil below the excavation invert. One sample from below invert, GL-3F (15.5 to 15.0 feet), had a TPH level of 30 mg/kg. All other samples from soils below invert had no detectable hydrocarbons. In addition, the samples from GL-4 beneath the former pump _. islands had no detectable hydrocarbons. The source of the backfill is unknown. Hydrocarbons were not noted in the excavated soil by the County representative during excavation of ti;e three tanks. It gasoline is assumed that mixing of soil occurred during excavation of the four tanks, thus it is difficult to determi,3e which, if any, tank contributed hydrocarbons to the soil. In addition, to fill the voids left by the removea .tanks, backfill material ` had to he brought in from off site. The the off-site material is unknown. Regardle:ss '1ofethe f source, soils below the site have detectable levels o hydrocarbons. f 2. Groundwater from all monitoring wells had benzene levels at cr above the California Department of Health Services (DUS) action level of 0.7 ug/l. Monitoring we! I MW-4 had a toluene level above the DHS action level of 100 ug/l, Monitoring wells -4W-3 and W-4 had xylene, levels above to DHS action level of 620 ug/i. Monitoring well MW-4 had the highest level of all detectable components. With the exception of MW-1 , levels Gf the B.•X components in tine other walls have ris' n since the initial sampling. In addition, MW--3 and - MW-4 had detectable levels of ethyl'benzene where they did not in the initial sampling.