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07 June 2002 AGE-NC Project No. 99-0645 Page 7 of 9 The six SVE borings will be advanced utilizing a truck--mounted drill rig equipped with 8-inch diameter hollow stem augers, the borings will be advanced to depths of approximately 45, 50. 55 or 70 feet bsg, respective to their completion depth. The SVE wells will be completed with 2-inch diameter, schedule 40 PVC well casing emplaced through the hollow stern augers. Each SVE well will utilize slotted well casing (0.030-inch screen size) from 15 feet to 45 feet bsg or from 25 to 55 feet bsg: the dual-screened well will utilize slotted well casings from 20 feet to 35 feet and 40 feet to 70 feet bsg. A #3 Lonestar Lapis Luster sand will be poured down the annulus between the well casing and the inner wall of the hollow stem auger. The falter pack will be placed adjacent to the screen from the bottom of the boring to a point approximately 1 feet above the top of the screen. For the dual- screened well, a due] filter pack will be installed, below and above a bentonite chip seal From 35 feet to 40 feet bsg. 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 two foot interval of bentonite pellets (annular seal) will be placed above the upper portion of the filter pack. Portland cement will be utilized to grout from the annular seal to surface grade. A SVE well construction diagram is depicted in Figure 5 and 5A. 4.3. SOIL VAPOR EXTRACTION PIPING NETWORK A network of two-inch diameter, schedule 40 PVC piping will be installed in 6-inch wide by 12-inch deep trenches at the site. The PVC piping will be routed from each SVE well head to a vapor dropout drum; the vapor dropout drum will be directly connected to the vapor extraction system. A PVC ball valve will be installed at each SVE well head so that vapors can be drawn from each well independently. A plan of the proposed piping system is depicted in Figure 4. 4.4. SOIL VAPOR EXTRACTION SYSTEM DESIGN A catalatic destruction process utilizing an electric heated catalatic oxidizer vapor extraction system (VES) is proposed for extracted hydrocarbon vapors (Figure 6). The VES should be able to operate between 175 and 200 cubic feet per minute (eft). Soil vapors will be extracted fi•om the proposed configuration of extraction wells using a vacuum blower and routed to the catalatic oxidizer. -advanced GeoCnvironmenta4 Inc.