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• 21 July 1991 (GeoAudit MDC Ukiah-1.9) Page 2 of 3 collected from each section (samples B-1 through B-25) using a core sampler pre-loaded with two 3-inch brass tubes from a depth of 1 -- 2 feet. For each sample, the ends of the lead brass tube were immediately covered with aluminum sheets, capped and sealed with tape. Figure 1 depicts the sampling location. The samples were logged on a chain of custody form and transported in a chilled container to Alpha Analytical Laboratories in Ukiah. Each sample was analyzed for total petroleum hydrocarbons for gasoline (TPH as gas) and purgeable aromatic hydrocarbons (BTE&X) in accordance with (DHS method and EPA method 8020) . Table 1 lists the results of the laboratory analysis. No TPH as gasoline was detected in any of the samples. BTE&X compounds were detected only in Sample B-12 at very low levels. Of the BTE&X compounds, only toluene and xylenes were detected at levels of 0. 0097 and 0. 0071 µg/g, respectively. This indicates the successful degradation of the contaminants by the microbes. No benzene was detected in the sample. The levels of the detected aromatic constituents are well below the State Drinking Water Standard. It should also be noted that bioremediation is an on-going process. These samples were collected on 26 June 1992 and the microbes have had several additional weeks to further degrade the hydrocarbon contaminants. Geological Audit Services proposes to use the "clean" portions of treatment cell "B" (approximately 600 cubic yards) as backfill for the excavation. The portions of the treatment pile that contained detectable levels of contaminants (approximately 25 cubic yards) should be transported off-site for disposal. TREATMENT CELL "C" A total of eleven soil samples (samples C-1 through C-9 , Ukiah#1 and Ukiah#2) were collected from treatment pile "C" (approximately one sample per 50 cubic yards of treated soil) using the same protocol as before. The samples were collected on 10 June and 26 June 1992 . These samples were transported in a chilled container to Alpha Analytical Laboratories. Each sample was analyzed for total Petroleum hydrocarbons for gasoline (TPH as gas) and purgeable • aromatic hydrocarbons (BTE&X) in accordance with (DHS method and EPA method 8020) . The laboratory results of these samples are also listed in Table 1 . t No TPH as gasoline or BTE&X were detected in any of these samples.