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04 September 2007 AGE NC Project No. 95-0121 Page 6 of 9 After installing the well casing in each pilot boring, a filter pack material consisting of pre-washed #2/12 sand will be added through the augers over the screen interval to approximately two feet above the screened interval. Following placement of the filter pack, the well will be surged to assist in settling the filter pack. Additional sand will be added if settling occurs. A nominal two-foot bentonite seal will be placed above the filter pack to minimize the potential for grout penetration into the screened section of the well. The bentonite seal will be formed by pouring bentonite pellets into the annulus and allowing them to settle on the filter pack. The bentonite pellets will be allowed to hydrate for a minimum of one-half hour prior to grouting. The remaining annular space will be filled within one foot of the ground surface with a cement grout. The grout mixture will consist of Type I/II portland neat cement and not more than 6 gallons of water per 94-pound sack of cement. The grout will be placed by pumping through tremie pipe. A grouting inspection will be scheduled with EHD personnel . 3.3 . WELL DEVELOPMENT AND WELL ELEVATION SURVEY Development of the proposed wells will consist of a combination of bailing with a stainless steel bailer to remove the major portion of fine-grained sediment from inside the well, surging to flush out or draw in sediment from the filter pack and additional ground water evacuation (purging) with an inertia bailing pump to finish the removal of fine-grained sediment. Developmental purging activities will be continued until field parameter (pH, electrical conductivity, and temperature) readings have stabilized and purged water is visually sediment-free. Following completion of the monitoring wells, well elevations and locations will be surveyed by a California-licensed surveyor relative to a local elevation benchmark. 3.4. DPE SYSTEM DESIGN AND IMPLEMENTATION A portable oil-ring blower extraction system with 240Volt, 3-phase generator, electrical heated catalytic oxidizer and 20,000-gallon holding tank (Figure 5) will be placed at the site for one event consisting of a five-day operational period. On the initial day of the five-day period the blower system will be attached to EW4 (Figure 6), which will be used as a DPE extraction well and vacuum readings will be obtained from surrounding wells V W- 1 through VW-5 (Figures 2 and 3). The use of four-inch diameter well EW- 1 with a screened interval of 20 feet bsg to 40 feet bsg will enhances the potential for vapor recovery from the exposed saturated zone, after the de-watering of the DPE remediation well occurs. Additionally, ground water samples collected from well EW- 1 have been reported to be heavily impacted and the well is located near the former UST area. The test will Adw omd GeoEnvironmental, Inc.