ARCHIVED REPORTS_XR0007931 - Laserfiche WebLink

Home Browse Search

1 ' 15 March 2000 AGE-NC Protect No 96-0229 ' Page 3 of 5 ' the ground water flow direction was generally toward the northeast at a gradient of 0 002 ft/ft, or approximately 11 feet per mile (Figure 3) Ground water was approximately 20 to 22 feet above the screen intervals at MW-1 and MW i 0-B ' 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES A total of eleven ground water samples were submitted to a DHS-certified laboratory in January ' 2000 TPH-g was detected in water samples collected from wells MW-1, MW-2, MW-3, MW-6, MW-7, and MW-8 at concentrations ranging as high as 68,000 micrograms per liter (µg/1) ' BTEX compounds were detected In ground water samples collected from wells MW-1, MW-2,MW- 3, MW-6, MW-7, and MW-IOB at concentrations ranging as high as 10,000 µg/l (xylene, MW-2) The greatest benzene concentration was observed at MWA at a concentration of 7,300 µg/l MTBE was detected utilizing EPA Method 8020 in ground water samples collected from wells MW-1, MW-4, MW-7 and MW-8 at concentrations ranging as high as 470 µg/l MTBE was confirmed utilizing EPA Method 8260 in samples collected from wells MW-1, MW-2, MW-4, MW-6, MW-7 and MW-8 at concentrations ranging as high as 650 ,ug/l, TBA was detected in ground water samples collected from wells MW-4 and MW-8 at concentrations of 7 6 µg/1 and 6 4 µg/l, respectively No other fuel oxygenated additives were detected above laboratory reporting limits from the analyzed samples tAnalytical results of the ground water samples are summarized In Table 2 The laboratory reports (Castle Analytical Laboratory Reference No 2779 and McCampbell A.nalyticaI Inc I D No 29637 Ithrough 29647) and chain-of-custody forms are presented In Appendix B 4.0 SUMMARY AND CONCLUSIONS The implications from the findings of the January 2000 investigation are • Ground water monitoring data collected in the area of wells MW-1 through MW-10 indicated a ground water flow direction generally toward the northeast at a gradient of 0 002 ft/ft The flow direction is close to the norm for,the area Due to the low gradient at the site, slight variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify ground water flow direction • The dissolved BTEX and MTBE plume is at least 20 feet thick in the area of MW-1 and MW-2, with depth, the dissolved BTEX and MTBE plume apparently grades from lower concentrations to higher concentrations Advanced 0(oFn%trnnmental,Inc