ARCHIVED REPORTS XR0000155 - Laserfiche WebLink

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CrIN IRC. SACRAMENTO • 6. 0 CONCLUSIONS AND RECOMMENDATIONS In summary, Versar operated a soil-vapor extraction pilot study at the Pacific Bell Ashley Lane facility for a total of 89 days. The SVE system was operational for 66 days and during that time removed an estimated 0 . 532 gallons of diesel from the impacted soils at the site. Based on the operational data from the study, Versar concludes that the subsurface at the site is suitable for soil- vapor extraction implementation. However, although some petroleum hydrocarbons have been removed from the subsurface, the low volume of diesel product removed from the subsurface indicates that the impacted soils cannot be satisfactorily remediated by soil--vapor extraction. Therefore Versar makes the following recommendations rregarding the site: • An additional single borehole should be drilled in the vicinity of EW6. The borehole would be used to collect soil samples to determine accurate current contamination concentrations and bacterial count in the soil . The soil samples should be analyzed for total petroleum hydrocarbons as diesel and bacterial colony forming units (CFU) . The analytical results should be compared to previous data to determine the actual reduction in residual diesel concentrations in the soil. The CFU count may be used to determine the natural degradation ability of the soil. • The soil contaminant loading characteristics should be determined based on the borehole analytical data. The loading characteristics may be used in the Designated Level Methodology to determine whether the residual contamination presents a threat to ground water in the area. • If it is determined that the impacted soils do not currently present a threat to ground water, the surface area of the impacted soils should be sealed to ensure that any percolation of surface water does not leach residual contamination to . non-impacted soils. 17