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Ge06gical7'ecknus Inc. Page 2 �. Additional Site Characterization And 1"Quarter 2004 Groundwater Monitoring Project No.425.2 March 22,2004 �. On August 20, 2002, GTI prepared and submitted the work plan Additional Soil and Groundwater Investigation. In a letter dated October 21, 2002, Nuel C. Henderson, Jr., R.G., SJCEHD, found the work proposed to be adequate and necessary with some conditions. This report documents the work performed in accordance to the October 2002 work plan including the installation of four additional groundwater-monitoring wells at the site during September and October of 2003. This report also documents additional site work and the first quarter 2004 groundwater-monitoring event. 2.0 SOIL & GROUNDWATER INVESTIGATION '-' Geological Technics Inc. supervised the installation of four groundwater-monitoring wells (MW-2X, MW-101, MWi06 and MW201) between September 23 and October 21, 2003. The locations of the new monitoring wells are shown on the site map (figure 2). Monitoring well permits were secured from the San Joaquin County Environmental Health Department (SJC/EHD). The local regulatory agency was notified 48 hours prior to commencing work. The subsurface was cleared of underground utilities by notifying Underground Service Alert. 2.1 Monitoring Well Installation On September 23, 2003, a hollow stem auger drill rig owned and operated by V&W Drilling ..� (C57# 720904) arrived at the site. The rig was set up near the location of the proposed deep monitoring well (MW-201). The location was cleared by hand auger to 5-feet bgs. The filter pack bridged during the first four attempts. By noon, the well had caved in to 25-feet bgs and was redrilled to depth. 'r The rig was moved to the location of an intermediate monitoring well (MW-101). Heaving sands delayed progress again and by 8 p.m. it was decided to try again on the 24`' of September. The next day heaving sands were still a problem and after six hours of attempting to set the well it was decided to abandon the location and try mud rotary at the earliest possible schedule. MW-101 was grouted to surface. On October 3, 2003, GTI and V&W arrived on site and relocated MW-101 two-feet north of original location. MW-101 was set by 2 p.m. and we moved the rig to the proposed location of MW-2X. Drilling problems continued and by 1 I p.m., the well was abandoned. �- On October 21, 2003, GTI and V&W arrived on site and installed MW-106 and MW-2X. The monitoring wells were constructed using 2.0-inch diameter schedule 40 PVC casing ,., with flush threads. The details of construction are listed in the table below and a summary of well construction is included as Table 1 in Appendix A.