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1,.r .,y <br /> it May 1992 <br /> (GeoAudit CV43F3-1. 15) <br /> Page 2 of 5 <br /> located in a shallow drainage ditch south of the above ground <br /> diesel tank. <br /> GEOLOGY/HYDROGEOLOGY �g3� <br /> The site is underlain by unconsolidated Quatern y sediments. The <br /> upper 25 feet consists of unconsolidated sil sands and clayey <br /> sands. Locally, groundwater is about 70 - 8 feet below surface <br /> grade (San Joaquin County Flood Control, 1991) . <br /> Data obtained from wells installed approximately 400 feet west of <br /> the subject site by the Marley Cooling Tower Company (MCTC) , <br /> indicates groundwater to be at 85 to 90 feet below ground surface <br /> (Quarterly Groundwater Monitoring MCTC - October 1991; Hargis & <br /> Associates, Inc. ) . The MCTC well data also indicates that <br /> groundwater in the area is flowing to the northeast. However, the <br /> flow direction can vary seasonally due to influences from <br /> agricultural pumping. <br /> eZ <br /> EXCAVATION h <br /> The contaminated soZliwas excavated in three phases. On 18 <br /> September 1991, the fphase of excavation was initiated. This <br /> phase resulted in tP4 removal of approximately 1, 000 cubic yards of <br /> soil. The excavat,ai.on process created a trench approximately 180 <br /> feet in length./ A representative of Falcon Energy Associates <br /> collected eight soil samples. The samples were analyzed for total <br /> recoverable petroleum hydrocarbons (TRPH; EPA inethod 418 . 1) on-site <br /> by Sequoia Analytical using a mobile laboratory. Appendix B shows <br /> the approximate location of the samples and the analytical results <br /> from the mobile laboratory. <br /> Approximately 800 cubic }yards of contaminated soil were removed <br /> during the second phase of excavation. On October 4 , 1991 nine <br /> samples were collected by a representative of GeoAudit from the <br /> floor of the excavation trench, at intervals of 20 feet (CARD-1 <br /> through CARD-9) . <br /> The samples were collected from the excavator bucket using a metric <br /> soil sampler preloaded with two clean, 2 . 5 by 3 inch brass tubes. <br /> The ends of the lead tube were covered with aluminum sheets, <br /> capped, sealed with tape and stored on ice. <br /> The samples were transmitted to Western Environmental Science & <br /> Technology (WEST) and analyzed for total petroleum hydrocarbons <br /> (TPH as gasoline and TPH as diesel) and purgeable aromatics (BTE&X) <br /> in accordance with EPA methods 8015 and 8020. Figure 2 shows the <br />