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l ' I ` 05 May 1997 C AGE-NC Project No 95-0112 Page 3 of 14 ' Quarterly ground water monitoring began in June 1992 Monitoring well MW-3 was not sampled between September 1987 and April 1995 due to the drop in ground water elevation at the site, MW-2 has riot been sampled since September 1987 due to the drop in ground water and the subsequent ' installation of MW-5 approximately 5 feet south of MW-2 Sampling of MW-6 and MW-8 was discontinued following the January 1996 monitoring due to their consistent up-gradient location and the non-detection of petroleum hydrocarbons Ground water flow toward the northwest was ' calculated for the June and August 1992 monitoring events Since that time,ground water has flowed consistently toward the south to southwest Past and current analytical results of ground water [ samples are included in Table 6 t 24 REMEDIATION WELL INSTALLATION ' n 18 August 1993 boiin RW-1 was installed near the southeast coiner of the building at a 15° 0 g � g g r angle fiom vertical toward the former UST location The boring was completed as a 4-inch diameter IC remediation well with screened PVC casing from 10 to 40 linear feet and from 45 to 501111ear feet Petroleum hydrocarbons were detected in soil samples collected during the well installation at ' concentrations as high as 12,000 ppm Analytical results of soil samples are summa)t.7ed on Table I The boring log is included in Appendix A The well installation was described in a Problem Assessment Report (PAR) dated January 1994 and prepared by GAS 25 SLUG TEST Slug tests were performed on monitoring wells MWA, MW-4, MW-6 and MW-7 by GAS on 18 November 1993 The tests included both water withdrawal and infection methods A pressure ' transducer was used to measure the water column in the wells during the tests and the results were graphed Hydraulic conductivity was calculated to range from 0 68 ft/day to 143 2 ft/day The aquifer transmissivity was calculated to range from 375 ft2/day to 7,150 ft2/day with an estimated [ aquifer thickness of 50 feet Details of the aquifer tests and calculations were presented in the PAR prepared by GAS 26 VAPOR EXTRACTION PILOT TEST A vapor extraction pilot test was conducted using vadose-zone well RW-1 as the extraction well The well was first tested on 16 November 1993, however, due to equipment failure,this test was aborted ' after only three hours and repeated on 17 December 1993 An effective radius of 25 to 35 feet was calculated for vapor extraction at the site High hydrocarbon concentrations were detected in air 4 samples collected during the pilot test Laboratory results of vapor samples collected during the test 1L