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5 1 5 - - <br /> 5.0 DISCUSSION OF RESULTS <br /> The analytical results for this and previous monitoring fnd <br /> ield <br /> sampling are summarized in Table 1. The water sampling <br /> survey forms presenting the results of the field sampling and <br /> observations are presented in Appendix A. The laboratory <br /> report and chain of custody record are presented in <br /> Appendix 3. <br /> A ground water gradient map, based on the depth to ground <br /> water measurements collected on May 17, 1591, is presented in <br /> Figure 3. The ground water flow gradient, as calculated from <br /> this sampling event, is to the northeast at approximately <br /> 0.001 foot/foot across the site. <br /> Resuits of monitoring and laboratory analysis indicate the <br /> following: <br /> o Monitoring Wells MW-2, MW-3, MW-4, MW-5, and MW-6 <br /> were dry, reflecting a, regional fall in the ground <br /> water table. <br /> o Analysis of ground water samplleoffbenz e9 detected <br /> 2,100 ppb of TPH-G and 310 pp t.: <br /> o Monitoring Wells mW-7 and MW-8 did not contain TPH-G <br /> and BTEX at or above reported detection limits. <br /> o The ground water gradient direction, as calculated <br /> from this sampling event, is to the northeast. <br /> 6.0 CONCLUSIONS <br /> 0 <br /> 1. The presence- of free product beneath the site, first <br /> n MW-1 through MW-4, is currently <br /> reported in 1987 ii <br /> unknown due to the apparent drop in ground water <br /> elevations. The soil gas survey conducted in 1989, E <br /> however, suggests the continued presence of petroleum <br /> hydrocarbon vapor in the soil in this area. Current I <br /> ground water quality data is required. <br /> 2. The source(s) of petroleum hydrocarbon constituents <br /> present in MW--9 has not been identified. Additional <br /> information regarding the tank installation and <br /> removal, in particular, the removal of the waste oil <br /> tank and related soil and ground water sampling, is <br /> needed. <br />