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r , Dpp <br /> —^-4 FX—D— <br /> CLEARWATER <br /> G R O U P I N C <br /> Entrronnieatal Services <br /> 4.0 RESULTS <br /> 4.1 Water Level Gauging Data <br /> On May 30, 1996, the depths to groundwater in the six monitoring wells ranged from <br /> 18 79 to 19 86 feet below grade Groundwater elevations, calculated for the purpose <br /> of estimating flow direction and gradient, were approximately 1 foot higher than <br /> groundwater elevations measured on February 27, 1996 The groundwater elevation <br /> contours shown on Figure 3 indicate that groundwater flow is toward the <br /> northwest The groundwater gradient is 17% across most of the site, but is only <br /> 0 4% between MW-2 and MW-6 This change in gradient appears as a flattening of <br /> the water table west of the former USTs, which is consistent with the configuration <br /> of the water table during previous gauging events <br /> 4.2 Groundwater Analytical Results <br /> Petroleum hydrocarbons were detected only in groundwater samples collected from <br /> monitoring wells MW-1, MW-2, and MW-5 The highest detected concentrations of <br /> ® TPHg and benzene were 36,000 parts per billion (ppb) and 240 ppb, respectively, in <br /> the sample from MW-2 TPHg and benzene concentrations were 540 ppb and 9 6 <br /> ppb, respectively, in the groundwater sample from MW-5, and 100 ppb and 10 ppb, <br /> respectively, in the sample from MW-1 <br /> A summary of groundwater elevations and analytical results is presented on Table <br /> 1 Hydrocarbon concentrations are presented graphically on Figure 4 Copies of the <br /> laboratory report and chain-of-custody form are attached as Appendix B <br /> D-101 2Q96 3 <br /> June 21, 1996 <br />