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i 4-3 <br /> 4 3 SOIL - FORMER SEPTIC SYSTEM LEACHFIELD <br /> Analyses of soil samples collected at depths of 8 to 10 ft-bgs from borings in the former <br /> septic system leachfield indicated that concentrations of hexavalent chromium, TCL VOCs, <br /> ' and TPH-purgeable fuels as diesel were not detected <br /> 4 4 SHALLOW GROUNDWATER <br /> In general, ground water was encountered in the silty clay unit at a depth of about 12 to 16 <br /> ' ft-bgs but came to static equilibrium in monitoring wells approximately 2 feet higher This <br /> indicates that the water-bearing zone is under locally confined or semi-confined conditions <br /> The measurement of ground water elevations indicates that ground water flow is to the north- <br /> northwest, with a hydraulic gradient of approximately 0 004 ft/ft The total depth of the <br /> water-bearing zone is not known at this tune The hydraulic conductivity of the upper por- <br /> tion of the saturated zone is approximately 3 17 x 10' ft/sec based on the slug test performed <br /> ' in Momtoring Well MW-6 <br /> BTEX constituents were detected in the sample collected from Monitoring Well MW-1, <br /> which is located in the former LIFT pit. These compounds were not detected in any other <br /> ground water sample collected TPH-purgeable fuels as gasoline was detected in the ground <br /> water samples collected from Momtoring Wells MW-1 and MW-6 The concentrations of <br /> ' TPH-purgeable fuels as gasoline in these samples were similar, although "high boiling" point <br /> Momtohydrocarbons were detected in the sample from Monitoring Well MW-6 Note that <br /> r-ing Well MW-6 is downgradient of the former UFr location <br /> Ammonia was detected in ground water samples collected from Monitoring Wells MW-1, <br /> MW-2, and MW-3 during the initial sampling round Ammonia was also detected in the <br /> field rinsate blank sample prepared for that sampling round The concentrations of ammonia <br /> in the ground water samples are suspect because they were relatively low and did not exceed <br /> ' the concentration detected in the rinsate blank by 2 times <br /> Ground water samples were analyzed for total (unfiltered) RCRA metals. Total metals <br /> analysis concentrations are often affected by the turbidity (suspended solids) of the sample <br /> 29023 ____7 <br /> A'r it <br /> "REALISTIC SOLUTIONS FOR HAZARDOUS WASTE PROBLEMS rM= <br />