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... Geolagica(Technics 2nc. Page 2 Pitot Test Report COE-Arco Project No.750.2 August 8,2000 2.0 SUMMARY OF WELL .INSTALLATION In accordance with the approved work plan and for the purpose of determining if the site is conducive to vapor extraction as a remedial alternative, Geological Technics Inc. drilled and installed four vapor extraction wells according to the following schedule: '-r • VEW-1 and VEW-2 were drilled on April 29, 1999. • VEW-3 and VEW-4 were installed on July 30, 1999. ,.. The four (4) soil borings were drilled (2 to a depth of 55 feet and 2 to a depth of 27 feet) and converted into vapor extraction wells. The borings, VEW-1 and VEW-2 were drilled at the eastern edge of the site, under the former sidewalk along the old Escalon/Bellota Road. The borings for VEW-3 and VEW-4 were drilled in the northern part of the excavation, adjacent to the northern dispenser island (Figure 2, Site Map). The vapor extraction wells were constructed using 4-inch diameter PVC casing with flush +� threads. The table below shows the construction details. Well o. Dia./Tl) creep Slot Filter Pack Trans. Grout Scal �.. _ Seal VhW-_T___T755"___ - 0- _� 4"T27T -—10-27, ea gravel $.5_-7 -6.54�' 0-6.5' ea grave _ _4' - _l-" ea gravel-10- A surface seal was achieved by pumping a neat cement grout via a tremie tube {augmented with <4% bentonite) from the top of the Transition Seal to within 5 feet of the ground surface. The wells were cut off five feet below ground surface, capped, covered with steel plates and buried with dirt. This was done to allow the road, sidewalk and other +... improvements to be completed without damaging the wells. Soil samples collected from VEW-1 showed only the presence of low levels of Xylene and �. MTBE. Low to moderate levels of BTEX, TPH-G and MTBE were detected in the soil samples from MW-1, which is adjacent to VEW-3 & VEW-4. Soil analytical data is included in Table 1 of Appendix A. On June 27, 1999, GTI and Del Tech personnel used a backhoe to expose the tops of the two vapor extraction wells, VEW-I &VEW-2. The new Escalon/Bellota Road now covers these two vapor extraction wells. A trench was dug at approximately 4 feet below grade, heading to the west from the vapor wells. Conveyance piping was laid in the trench and VEW-1 & VEW-2 were hooked to it. The conveyance piping was stubbed off at approximately 3 feet below ground surface at the location of MW-1, VEW-3 and VEW-4. The trench was backfilled and compacted. On April 12, 2000, the work to bring all of the wells to surface grade and enclose them inside utility boxes was completed at the site. A full discussion of the well installation and soil testing is included in the Additional Site Characterization Report submitted by GTI on January 31, 2000.