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w � On May 17, 1994, the soil was inoculated with a bacteria medium to promote the degradation of petroleum hydrocarbons. Approximately 250 gallons of inoculant were sprayed over the soil piles.The inoculation was performed by Mr.Jim Hoeltgen, GeoAudit's microbiologist.After inoculation was completed,the pileswere covered with plastic sheeting. Bioremediation progress was monitored by collecting soil samples from the inoculated soil. Two sets of confirmatory samples were collected from the treated soil. Samples SP1-1, SP1- 2, SP2-1, SP2-2, SP3-1, SP3-2, SP4-1 and SP4-2 were collected on June 14, 1994. Samples SP1-3, SP1-4, SP2-3, SP2-4, SP3-3, SP3-4, SP4-3 and SP4-4 were collected on August 1, 1994. Soil sample locations are shown on Figure 1. All samples were collected using a metric soil sampler loaded with two precleaned 2-inch by 3-inch brass sleeves. For each sample, both ends of the lead tube were covered with aluminum sheets, capped and sealed with tape. The samples were then stored on ice and transported under chain-of-custody to McCampbell Analytical Inc. in Pacheco, California (MAI). Samples from each stockpile were composited 2:1 and analyzed for total petroleum hydrocarbons (TPH as Gasoline) and volatile aromatics (BTE&X) in accordance with EPA methods 8015m and 8020. FINDINGS Concentrations of petroleum hydrocarbons have decreased since inoculation with the bacterial medium. Samples collected from soil piles SP-3 and SP-4 indicate that petroleum hydrocarbons are no longer present. However, TPH as gasoline was detected in samples from soil piles SP-1 and SP-2 just above the method detection limit (MDL) of 1.0 ppm. The analytical results of the soil samples are summarized in Table 1. The laboratory reports and chains-of-custody are included in Appendix A. CONCLUSIONS AND RECOMMENDATIONS No petroleum hydrocarbons were detected in stockpiles SP-3 or SP-4 during either confirmatory sampling event. Soil from these two stockpiles should be returned to the excavation as backfill material. Additional backfill material may be obtained by moving native soil on-site to fill the excavation to surface grade. Low concentration of petroleum hydrocarbons remain in stockpile SP-1 and SP-2. Because of the low concentrations of remaining hydrocarbons, this soil should be turned over and allowed to aerate in addition to the bioremediation. The stockpiles should then be resampled to confirm the removal of the remaining hydrocarbons. Upon completion of the soil remediation, preparations should be made for the installation of groundwater monitoring wells as outlined in workplan prepared by GeoAudit in September 1993. Geological Audit Services,Inc. 792-S/CALD-BIO.RPT