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l. <br /> s <br /> 27 May 1992 <br /> (GeoAudit MDC Ukiah-1. 9) <br /> Page 5 of 5 <br /> BIOREMEDIATION <br /> 300 South State Street <br /> Ukiah, California <br /> Bioremediation of contaminated soils was initiated on 31 October <br /> 1991. The treatment cells consist of a 6 to 8 inch depression lined <br /> with 10 mil visqueen. Soil was then moved from the large pile and <br /> placed on the visqueen to a depth of approximately three feet. The <br /> hydrocarbon-consuming bacteria were then applied to the treatment <br /> cells and the entire pile was covered with 10 mil visqueen. The <br /> analytical results are summarized in Table 2. <br /> On 6 December 1992, 16 discrete soil samples were obtained from the <br /> original treatment cell (see Figure 4) . The samples were analyzed <br /> for Total Petroleum Hydrocarbons (TPH-gasoline) and BTE&X. Twelve <br /> of the sixteen samples collected did not indicate the detection of <br /> TPH-g and BTE&X. Table 2 lists the results of the laboratory <br /> analysis. <br /> A report on the original treatment cell and laboratory analysis was <br /> transmitted to the RWQCB - North Coast Region on 7 January 1992 . <br /> The report describes the details of sample collection and <br /> laboratory analysis. <br /> Partial backfilling of the excavation was undertaken on 31 March <br /> 1992. Approximately 300 - 325 cubic yards of soil from the <br /> original treatment cell was used to partially backfill the <br /> excavation. The soil was screened for the presence of volatile <br /> organics during the backfilling procedure. Only the portions of the <br /> treatment cell which did not indicate the presence of hydrocarbon <br /> contamination were used for backfill. The remaining soil (about 75 <br /> - 100 cubic yards) was consolidated and covered with 6 mil visqueen <br /> for continued treatment. <br /> On 30 April 1992 , a second treatment cell was created. At this <br /> time, the remaining 1,800 cubic yards of contaminated soil were <br /> treated. The soil was piled on 10 mil visqueen to a uniform height <br /> of approximately three feet. The hydrocarbon-consuming bacteria <br /> were then applied to the treatment cell and the entire pile was <br /> covered with 10 mil visqueen. Sampling of the second treatment cell <br /> is scheduled for early June, upon which the bioremediation project <br /> will be completed. <br />