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JUL = ' 91 16 : 43 FREN1) IR0H111P0HL SCI ENG F'HGE . 004 C-5HADPU Fs91.2/V"Cs Wp.6 06/18/91 5. Allow specification of vacuum extraction equipment and offgas + treatment and design of an effective wellpoint system. 2-3 PILOT TEST ErALLATION 2.3.1 INSTALLATION OF VAPOR EXTRACTION WELLS (VEWs) j Prior to conducting a pilot-scale test at this site, it will be necessary to install ` three VEWs in Soil Area 14 and three VEW$ and two vapor monitor wells (VMWs) in Soil Area S. U.S. Army Toxic and Hazardous Materials Agency (USATHAMA) geotechnical specifications for monitor wells will be followed!for the installation of the VEWs and VMWs, and USATHAMA-approved well construction materials will be used. An ESE geologist will be present during drilling. Physical samples will be collected, and well locations will be entered in the Installation-Restoration Data Management System (IRDMS). The VEWs and IVMWs should be installed as follows: Central Area (Soil Area 14) 1. The three VEWs in Soil Area 14 will be installed at intervals of 15 ft along two radials (90 degrees apart). The first VEW will be inst ed approximately 30 ft southeast of monitor well 455 (see Fig. 2-3). 2. The three wells will be labeled VEW 1-14, VEW 2.14, and VEW 3-14 (see Fig. 2-3). 3. Soil samples will be collected every 2.5 ft in the first boring to verify the subsurface stratigraphy encountered in the pilot test area. 4. Based on expected subsurface stratigraphy developed during the Rt, the VEWs will be installed as outlined in Table 2-1 and Fig. 2-4. S. All lengths of pipe, both slotted and blank, will be connected by threaded joints. No glues or adhesives will be used. 6. The annulus of each well will be filled with clean sand pack to depths coinciding with the slotted intervals. Bentonite pellets will be placed �l 2-6 i