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• • In KLEINFELDER The highest concentrations were noted east and northeast of the rupture area near pushprobes PP- 20 and PP-21 and in areas where petroleum constituents were noted at greater depths (see Area C �l and D illustrated on Plate 3). The highest benzene concentration however was noted in a I composite sample PP5/PP6 located west of the rupture point. Several composite samples were non-detect for petroleum constituents in the southern portion of the footprint area. As might be expected composite sampling results varied when compared to subset discrete samples at the same locations and depth intervals. Discrete sampling analytical results were found to be higher in notable petroleum impacted intervals (0 - 12') and less in the transition zone (>12'). See �] Table 1, PP18 composite results and discrete samples collected at 10 feet and 16 feet bgs. 5.1.2. Discrete Soil Sampling Discussion Twenty-six (26) discrete soil samples were collected, 14 within the footprint area and 12 from perimeter pushprobe borings. Nine of the 26 soil samples were collected near the total depths of selected pushprobes located primarily in petroleum impacted areas. These discrete soil samples were collected to assess the vertical limits of petroleum impacted soil and to correlate with field observations and PID readings. These nine samples were collected from pushprobes PP2, PP6, PP10, PP11, PP17, �I PP18, PP19, PP21 and PP25. Sampling depths ranged from 7 to 24 feet. Eight of these nine soil j samples were non-detect for the requested petroleum constituents. One of the nine soil samples collected from PP19 at a depth of 19 feet had a reported TPH-D concentration of 9.5 mg/kg. Based on the discrete soil sampling results of these nine samples it appears the vertical migration of petroleum constituents was limited to the respective depths and locations where these nine soil I samples were collected, with the exception of PP19 at 19 feet. For additional discussion of f estimated limits of petroleum impacted soil and estimated volumes see Section 5.2 of this report. i Five discrete soil samples were collected from composite subsets from pushprobe locations PP6 and PP18. These soil samples were collected and analyzed for correlation to composite sampling and to assess petroleum concentrations limits with varying depths and for correlation with field observations. A brief discussion of findings for these samples is contained at the end of Section 5.1.1. Twelve discrete soil samples were collected from perimeter pushprobe borings G2, G3 and G4, to assess the lateral migration of petroleum constituents in soil outside of the footprint area. Soil samples from these three locations were collected at depths ranging from 5 to 43 feet bgs. Each of these discrete soil samples were non-detect for the requested analyses as listed in Section 4.3. Based on these sampling results it does not appear petroleum constituents are further migrating laterally in soil at the locations and depths sampled. I 5.2 ESTIMATED LIMITS AND VOLUME OF PETROLEUM IMPACTED SOIL Based on field observations including soil discoloration, odor,PID readings and analytical results Kleinfelder prepared Plates 3 and 4. Plate 3 illustrates a plan view of obvious petroleum impacted soil and estimated depths. Plate 4 estimates anticipated excavation limits at the 44843.T03/ST04R1025 Page 10 of 16 Copyright 2004 Kleinfelder,Inc. August 6,2004 �i