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I30 August 2004 i AGE-NC Project No 99-0592 IPage 6of13 ' 3.0. GROUND WATER MONITORING Between June 1999 and June 2004, four ground water monitoring wells have been Installed and ' sampled for petroleum hydrocarbons Initial ground water samples were collected in November 1999 To date, a total of eighteen ground water monitoring events have been conducted at the site Field sheets and the laboratory report from the quarterly momtormy� �lucte d%;une 2004 areJDJ Included in Appendix C Depth to ground water has ranged between 53 and 634 feet bsg at the ' former USTs locations,always within the screened interval of the wells,ground water flow direction has been consistently northeast at a gradient of approximately 0 0007 fl/fl Figure 10 shows the ground water gradient for the June 2004 monitoring event and a rose diagram of historical flow directions Table 7 contains historical depths to water and ground water elevations ' Petroleum hydrocarbon compounds were detected in one monitoring well (MW-1) during the monitoring program, TPH-g concentrations have decreased in samples from well MW-1, from 970 µg/1 in November 1999 to 300 µg/1 the last time it was successfully sampled, in March 2003, TPH-d was detected at concentrations up to 280 gg/l when analyzed, however the laboratory Indicated that gasoline range compounds were significant nearly every time BTEX compounds have been detected at the following maximum concentrations benzene (3 8 gg/1), toluene (1 3 µg/1), ethylbenzene (1 0 gg/1) and xylenes (2 7 µg/1) MTBE has been detected at concentrations ranging from 5 1 gg/l (March 2001)up to 180 gg/l(March 2003) Tertiary-amyl methyl ether(TAME)and TBA have been detected twice in the duration of sampling, at maximum concentrations of 6 4 gg/l and 13 gg/l,respectively 1,2-dichloroethane(1,2-DCA)was detected the three times it was included in the analysis at concentrations ranging from 14 gg/l to 22µg/1 Analytical ground water monitoring well data is presented in Tables 1 and 2 GeoTracker confirmation pages of the submitted laboratory EDF files are Included In Appendix B 4.0. CONE PENETROMETER TESTING PROCEDURES On 07 April 2004, one soil boring designated CPT-1 was advanced on-site(Figure 2)utilizing CPT technology, at the boring location, lithologic data was collected from the initial CPT boring and an immediately adjacent twin boring was then advanced to collect soil and grab ground water samples Iat selected depths 41 CPT LITHOLOGIC INVESTIGATION The CPT investigation utilized a 25-ton truck-mounted CPT drill ng equipped with 1 50-Inch diameter hollow-stem rods A hydraulic ram was utilized to advance a cone penetrometer tip J ' Advanced CeoEnvironmental,Inc