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17 April 2000 AGE-NC Project No. 95-0100 1 Page 3 of 6 ' 2.2. MONITORING WELL RE-INSTALLATION During the placement of the portland cement in the upper annular space of the soil boring, cement infiltrated the filter pack of well MW-3 to a depth of 55 feet bsg. Additionally, monitoring well MW-1 was damaged during re-development by Cal Nev and sand had infiltrated the casing to a depth of 50 feet bsg. Therefore, the two wells were abandoned under permit on 28 January 2000. ' Grout was pumped into the wells and pressurized to allow for the grout to enter the filter pack completely. On 03 February 2000 the two wells were re-installed at the site by Cal Nev. No soil sampling was conducted for the reinstallation of the these well, because previous data was available from the pilot boririg established earlier. The re-completion was similar to the initial well completion. Duringthe second installation of monitoring MW-3, the ortland cement again infiltrated the filter g p g ' pack of well MW-3 to a depth of approximately 55 feet bsg. This well was demolished as described above and re-established on 13 March 2000, in the same manner as described above. As-built monitoring well diagrams for each monitoring well are included as Appendix A. 2.3. MONITORING WELL SURVEY The casing elevation of each well installed for the UST investigation was surveyed relative to a ' bench mark near the site. On 30 December 1999, a California state-licensed survey engineer from Baumbach& Piazza,Inc. surveyed a reference point on the top of each ground water monitoring well at the site to the nearest 0.01-foot relative to the City of Tracy Bench Marks and Description at ' 121.48 feet above mean sea level (msl). The results of the monitoring well survey are contained in Table 1. The surveying report (Baumbach& Piazza) is presented in Appendix B.- 2.4. GROUND WATER DEPTH MEASUREMENT AND PURGING ' On 24 August 1999, a Solinst water level meter was used to measure the depth to ground water and the total depth of the ground water monitoring well MW-1, relative to the top of the well casing. After the depth measurements were collected, the monitoring well was purged using a Grundfos _ —submersible pump.--- On ump.--On 14 October 1999, a Solinst water level meter was used to measure the depth to ground water and ' total depth of monitoring wells MW-2 and MW-3 relative to the tops of the well casings. After • ground water depth measurements were collected, monitoring well MW-2 was purged using a Orundfos submersible pump. Well MW-3 was discovered to be damaged or incorrectly constructed. The monitoring well would not recharge water and therefore was not fully purged or sampled. Advanced CeAnvironmental,Inc.