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between 45 and 50 feet. <br /> 2 . 4 Initial Assessment and Drilling <br /> On 9 October 1992 , a soil boring was installed in the center of the <br /> gasoline tank cavity (Boring #1, Figure 2) . This boring was <br /> advanced to a depth of 60 feet. Samples were collected at five-foot <br /> intervals and analyzed for total petroleum hydrocarbons (TPH as <br /> gasoline) and volatile aromatics (BTE&X) . <br /> TPH as gasoline was detected in samples B1-20 (93 gg/g) , B1-30 <br /> (6, 100 gg/g) and B1-40 (13 gg/g) . Benzene, toluene and xylene were <br /> detected in all analyzed samples except B1-60, at levels ranging <br /> from 0 . 007 gg/g (xylene, B1-50) to 520 gg/g (toluene and xylene, <br /> B1-30) . Ethylbenzene was detected in samples B1-20 (3 . 5 Ag/g) , B1- <br /> 30 (170 gg/g) and B1-40 (0 . 37 gg/g) . The results were described in <br /> the Soil Boring Installation report dated 16 November 1992 , <br /> prepared by GeoAudit. <br /> 2 . 5 Monitoring well Installation <br /> On 9 and 10 March 1993 , three soil borings were drilled to a depth <br /> of 77 feet. Samples were collected at five-foot intervals and <br />. selected samples analyzed for TPH as gasoline and BTE&X. The <br /> borings were completed as groundwater monitoring wells (MW--1 <br /> through MW-3) . A benzene concentration of 0 . 0079 mg/kg was detected <br /> at a depth of 45 feet in the boring immediately south of the tank <br /> pit. No other contamination was detected in the samples analyzed <br /> from these three borings. <br /> 2 . 6 Groundwater Monitoring <br /> On 17 March 1993 , the casing elevations were surveyed, the water <br /> level in each well was measured, each well was purged and samples <br /> were collected. The hydraulic gradient was determined to be 0. 0073 <br /> ft/ft directed S 70 W. Benzene and Xylene were detected at <br /> concentrations of 3 . 7 gg/l and 1 . 1 Mg/1 in monitoring well 14W-2 . <br /> Both concentrations are slightly above the detection limits of 0. 30 <br /> gg/L and 0 . 50 Mg/L. <br /> A second monitoring event was conducted on June 24 , 1993 . Based on <br /> —depth-to-groundwater measurements, the hydraulic gradient was <br /> calculated to be 0 . 0025 ft/ft directed S 700E. Comparison of the <br /> March and June measurements indicates that water levels have risen <br /> approximately 2 to 2 1/2 feet in all wells. No petroleum <br /> hydrocarbons were detected in any of the samples in this monitoring <br /> event. <br /> 0 <br /> 2 <br />