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TPHD up to 6,800 ppm and relatively low levels of BTEX still remain in place near the former diesel <br /> tank location Soil samples collected from the two immediate bonngs indicate the diesel hydrocarbons <br /> are vertically localized and do not extend past 20-feet below grade <br /> Elevated Ievels of hydrocarbons were detected at approximately IO 5 feet below grade in the angle soil <br /> boring beneath the former gasoline pump island and extending to a depth of approximately 40-feet <br /> below grade in soil boring KIWI Trace levels of toluene have been detected at depths of 55 5 feet <br /> (0 010 ppm) and 65 5 feet (0 014 ppm) beneath the surface Trace levels of xylenes were detected <br /> in the 55 5 foot (0 017 ppm) sample. <br /> 4.2 Groundwater <br /> During the drilling of MW 1 groundwater was first encountered at approximately 69-feet below grade <br /> Subsequent to the installation of monitoring well MW 1 static groundwater rose to 67 55 feet below <br /> Lgrade The inferred flow direction of groundwater underlying the site is estimated to be in a <br /> northwesterly direction as discussed in Section 2 3 Toluene, ethylbenzene, xylenes, and TPHG were <br /> detected in the groundwater <br /> 5.0 WORKPLAN FOR ADDITIONAL SOIL/GROUNDWATER INVESTIGATION <br /> 5.1 Installation of Three Additional Groundwater Monitoring Wells r <br /> To further assess the subsurface conditions at the site, two soil bonngs will be advanced in the <br /> downgradient direction of the former underground gasoline storage tank area and one will be advanced <br /> in the upgradient direction The upgradient well will help define the Iateral extent of impacted soil <br /> detected beneath the former dispenser island The borings/wells will be drilled to a total depth of <br /> ' approximately 85 feet below grade. Soil samples will be collected at five-foot intervals and will be <br /> described and logged continuously according to the Unified Soil Classification System Hydrocarbon <br /> ' concentrations in the soil samples will be estimated in the field utilizing a photoionization detector <br /> (PID) The concentrations detected by the PTD will be recorded by the field geologist The three <br /> bonngs will be completed as groundwater monitoring wells using 4-inch diameter PVC screen and <br /> casing The proposed well locations are shown on Figure 5 Typical well construction is shown on <br /> Figure 6 <br /> R 042992 TIL 7 <br />