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1 <br /> I8 July 1991 <br /> (GeoAudit CV 43C4 . 1. 1) <br />' Page 2 of 4 <br />' presence of organic vapors using a photo-ionization detector (PID: <br /> Photovac, Micro Tip, 10. 0 eV, calibrated to isobutylene) . The soil <br /> profile was described in accordance with the Unified Soil <br /> Classification System. <br /> IBelow 50 feet, discrete soil samples were collected at 5-foot <br /> intervals ahead of the drill bit using a split-tube sampler loaded <br /> I with 3 precleaned 2 by 6-inch brass tubes. Each sample was <br /> immediately covered with aluminum sheets in its respective brass <br /> tube, capped and sealed with tape. <br /> i <br /> The samples were stored under ice and subsequently relinquished to <br /> Sequoia Analytical for analysis. Analyses for TPH in accordance <br /> with the DHS approved method for gasoline, and for purgeable <br /> I aromatic hydrocarbons (BTE&X) in accordance with EPA method 8020 <br /> were conducted on the samples. <br /> • After preserving the first brass tube sample, soil from the second <br /> brass tube was extruded into a plastic bag and screened for the <br /> presence of organic vapors using the PID. Subsequently, the soil <br /> was described using the same protocol as described above. To avoid <br /> I cross contamination the sampling equipment was steam cleaned and <br /> rinsed twice with water prior to each sampling run. <br /> The boring was converted to an extraction well on the same day. The <br /> well design is depicted on Figure 4 . <br /> FINDINGS <br /> The upper 9 feet consists of silty fine sand. This material is <br /> I assumed to be backfill for the former tank excavation. The native <br /> profile from 9 to 69 feet is composed of: <br /> I 1) fine sandy silt with interbedded fine sand layers from 9 to <br /> 21 feet; <br /> 2) fine sand, which coarsens downward to medium/coarse sand, <br /> from 21 to 31 feet; <br /> I 3) sandy silt, which coarsens downward, from 31 to 48 feet; <br /> 4) gravelly coarse sand from 48 to 55 feet; <br /> 5) and clay intercalated with silty-fine sand layers from 55 <br /> I feet to the bottom of the boring. This material was <br /> water-saturated below approximately 69 feet. <br /> Elevated organic vapor (OV) readings, ranging from 643 to 2 , 603 <br /> I parts per million (ppm) , were noted in the upper 47 feet of the <br /> soil profile. Moderate to low OV levels were encountered below 47 <br /> I feet (boring logs) . <br /> I <br />