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r <br /> 1 <br /> November 22, 1995 <br /> Page 6 <br />' FINDINGS <br />' Subsurface Conditions <br /> General subsurface llthologic units encountered during the current investigation are <br /> shown on geologic cross-sections A-A', B-B', and C-C', Figure 6 through Figure 8, <br />' respectively The uppermost soils encountered were comprised of clayey sand and <br /> silty sand horizons to depths that ranged from approximately 7 to 15 feet below <br />' ground surface (bgs) <br /> A clay horizon was encountered below the sands to depths ranging from <br /> approximately 21 to 24 feet bgs The clay had a maximum observed thickness of <br /> approximately 12 feet, and appears to be laterally continuous beneath the site <br /> A poorly-sorted sand and silty sand horizon was encountered beneath the clay in U- <br /> E, U-F and U-H at depths of 21 to 24 feet bgs The sandy horizon was observed to <br /> the maximum depth explored of 26 feet bgs in U-H , <br /> Groundwater was first encountered during dri ing in the uppermost sand horizon and <br /> underlying clay at approximately 10 feet bgs-land stabilized at approximately 9 feet <br /> bgs The groundwater monitoring wells were constructed in the shallow water- <br /> beanng zone Groundwater in this shallow zone flows to the northwest, at an <br /> approximate gradient of 0 004 foot/foot%A groundwater flow map for the June 2, <br /> 1995 monitoring event is shown on Figure 1 in Attachment D <br /> Soil Analytical Results - <br />' Soil analytical data indicate that residual petroleum hydrocarbons have impacted soils <br /> beneath the site TPH-g were detected at concentrations ranging from below the <br /> detection limit to 7,400 parts per million (ppm) The majority of TPH-g was <br /> detected in the northwestern portion of the property in U-A, U-B 1, U-C, U-1, and <br /> U-2, at depths of approximately 10 feet bgs, which correlates to the capillary fringe <br /> L (Figure 9) Benzene was not detected in any of the soil samples submitted for <br /> analysis <br /> Soil samples from U-11, U-2, and U-3 were analyzed for TPH-d/At these locations, <br />' TPH-d was detected at concentrations ranging from below the detection limit to a <br /> maximum of 480 ppm in U-1, at a depth of 10 5 feet bgs <br />' Sod samples from Boring U-3, located immediately downgradient of the former <br /> waste oil tank, were analyzed for purgeable organic hydrocarbons and metals <br /> Boring U-3 contained concentrations of chromium (31 to 35 ppm), nick (33 to 41 <br /> 3100971A1REPORTT2 <br />