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_ _ II Site Background Information : Quick N Save # 1 Page 5 of 6 Utilizing a semi-logarithmic plot of ground water draw-down vs . observation well distance to pumping well (Jacob straight-line method), a best-fit line was utilized to project a radius of influence for EW-1 at approximately 29 . 8 feet at 1 .0 GPM . Utilizing the Distance-Drawdown Method (Jacob straight-line method) for the first stage of the pump test ( 1 .0 GPM), a transmissivity was calculated at 10.6 ft2/day (equivalent to 79 . 1 gallons per day/ft) and a storativity value calculated at 0. 0012. For the second stage of the pump test (0.75 GPM), a transmissivity was calculated at 9 .4 ft'/day (equivalent to 70 gallons per day/ft) and a storativity value calculated at 0 .00031 (Appendix J). Based on transmissivity values of 10.6 ft2/day (first stage) and 9.4 ft2/day (second stage) and an aquifer thickness of 20 ft (screen interval at EW- 1 ), hydraulic conductivity values were calculated at 0.53 ft/day, or 1 .9 x 104 cm/s (first stage) and 0.47 ft/day, or 1 .7 x 104 cm/s (second stage) ; these hydraulic conductivities are consistent with a screened interval located within a silty fine sand. This suggests that although the pilot boring for EW- 1 encountered some coarser grained sand, the fine silty sand encountered between 30 and 55 feet bsg in previous pilot borings for MW- 1 through MW- 4 is more characteristic ofthe aquifer (see the AGE-prepared Quarterly Report - First Quarter 2004, dated 15 June 2004) . Laboratory analysis of extracted water during the pumping test detected elevated concentrations of TPH-g, BTEX, MTBE, and 1 ,2-DCA in both samples submitted for analysis. Concentrations were as high as 61 ,000 pg/1 TPH-g, 9,900 µg/I benzene, 23 ,000 µg/I toluene, 2, 500 gg/l ethylbenzene, 18,200 Itg/l xylenes, 220 µg/I MTBE, and 230 pg/l 1 ,2-DCA. All concentrations detected were significantly above the respective MCLS for each contaminant. SOIL VAPOR EXTRACTION PILOT TEST On 23 August 2005 , a SVE pilot test was conducted at the site. The pilot test operated for approximately 7 hours and was terminated due to stabalization. An induced vacuum potential was applied to the casing of vapor well VW-3 . The vacuum-induced pressure reduction was monitored at surrounding observation points (VW- 1 , VW-2, VW-4, and MW-2) with air-tight well caps pre- connected with Magnehelic vacuum gauges fitted to each observation well . A sample port was tapped into the PVC near the wellhead and a portable organic vapor meter equipped with a photo- ionization detector (PID : Microtip model 1000 calibrated to isobutylene) was used to measure organic vapor (OV) concentrations. The organic vapor concentrations, the induced vacuum potential atthe observation points, extracted soil gas flow rate, and revolutions per minute (RPM) of the SVE unit were measured at 0 .5-hour intervals and logged on field sheets . The SVE unit was operated at approximately 2,500 RPMs for the eight-hour test, with a flow rate measured between 30 scfm (standard cubic feet per minute) and 36 scfm. OV readings ranged from 1158 to 1401 ppm. Induced vacuum measured at the extraction well (VW-3) was a constant 94 inches of water. Based upon an effective vacuum potential of 0 . 1 inches of water, the calculated effective radius of influence of SVE at the site will be approximately 28 feet. TPH-g was detected in the soil gas/vapor samples at concentrations ranging from 8,700 µg/1 to AAvaneed GeoEnvironmental, Inc.