ARCHIVED REPORTS XR0006199 - Laserfiche WebLink

Home Browse Search

s � 1 30 September 2003 AGE-NC Project No 98-0465 r Page 3 of 4 t ■ y 1 1 f Wells MW through MW4 and wells MW2 through MW7, on the adjacent site were used to infer ground water flow direction and gradient The ground water flow direction was inferred to be northernly at the former UST location to northeast in the northwestern portion of the site, at a ground water gradient of 0 005 ft/ft or less Figure 3 illustrates the contoured ground water elevations as measured on 28 August 2003 ' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES 3 ' TPH-d and BTEX were not detected at concentrations at or above the laboratory reporting limits in any of the groundwater samples TPH-g was detected in groundwater samples collected from MW 1 4f at concentrations of 1,100 µg/1 This is the first time, since July of 2000, that TPH-g was detected ' in any monitoring wells located on the site ' MTBE was detected in samples collected from MW1, MW2 and MW3 by EPA Method 8260B at concentrations of 1,200µg11,5 0µg/1 and 14µg/1,respectively No other fuel oxygenated compounds were detected in the ground water analyses at or above laboratory detection limits Figure 4 illustrates the approximate extent of MTBE-impacted ground water Analytical results of water samples collected during August 2003 are summarized on Table 2, the ' laboratory report (CTEL Lab IDs 0308-138-1 through 0308-138-4), QA/QC report and chain-of- custody form are included in Appendix C ' 4.0. SUMMARY AND CONCLUSIONS ' ' Based on the findings from this investigation, AGE concludes , C The ground water elevations on-site ranged from 9 04 to 9 24 feet below MSL Ground water - ' flow was inferred to range between the north and northeast under a gradient of 0 005 feet/feet or less Ground water gradient and direction varied significantly between the May 2003 and August 2003 monitoring events ` ' 0 TPH-d and BTEX were not detected in the ground water samples collected and analyzed during the third quarter 2003 , , , , ' 0 TPH-g was detected in samples collected from MWl at concentrations of 1,100 µg/1 Historically, TPH-g has not been detected above,laboratory reporting limits in monitoring ' wells MW 1 through MW4 • MTBE was detected in samples collected from MW1,MW2 and MW3 at concentrations of 1,200 µg11, 5 0 µg/1 and 14 µg/1, respectively Detected concentrations of MTBE in wells Advanced GeoEavironmental,Inc