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' 30 June 2003 AGE-NC Project No 95-0103 Page 3 of 7 ' 2 3 1 Well Monitoring and Evacuation A Solinst water level meter was used to measure the depth to ground water in monitoring wells 1 MW-1 through MW-7 and vapor well EW-5, relative to the tops of the well casings (Table 1) The ground water elevation in each well was calculated by subtracting the measured depth to ground ' water from the surveyed casing elevation After water levels were measured,ground water(a minimum ofthree casing water-volumes per well) were evacuated(purged)from wells MW-1,MW-3,MW-4,MW-5,MW-7 and VW-5 Well MW-1 ' was purged of 30 gallons and vapor well VE-5 was purged of 13 5 gallons utilizing a waterra lift- bailer Wells MW-3 through MW-5 and MW-7 were purged of between 5 and 10 gallons of water utilizing polyethylene disposable bailers Temperature,pH and conductivity were measured for stabilization at regular purge-volume intervals ' from each well using an Oakton water analyzer,the field measurements are included in Appendix A Purged water was subsequently treated through the on-site ground water treatment system ' 2 3 2 Ground Water Sample Collection and Analysis ' Water samples were retrieved from each purged well using the dedicated disposable bailers after allowing the well to achieve a minimum of 80 percent recharge prior to sample collection The samples were transferred into 40-m1 EPA-approved volatile organic analysis(VOA)vials containing 0 5 ml of 18%hydrochloric acid as a sample preservative The samples were properly labeled and transported in a chilled container under chain-of-custody to Cal Tech Environmental Laboratories, Inc (CTEL)and MAI,both DHS-certified laboratories,for analysis The groundwater samples were analyzed for TPH-g in accordance with EPA Method 8015 Modified and • BTEX and MTBE in accordance with EPA Method 8260 3 0. FINDINGS From field data collected at the ground water treatment system between 21 Decumbei and 15 April 2003 , AGE determined the average TPH-g and benzene concentrations and the average flow rate,and calculated the approximate mass and volume of TPH-g and benzene removed Ground ' water flow direction and gradient was determined from the field data collected on 21 and . 23 April 2003, the contaminant impact to ground water was assessed from laboratory data Advanced CeoEnwronmental,Inc