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05 September 2002 AGE-NC Project No. 95-0100 Page 7 of 9 ' 3.5. MONITORING WELL INSTALLATION Based on the detection of MTBE in the grab ground water sample collected from the confirmation ' soil boring, a ground water investigation was required by the SJC-EHD. AGE submitted two work plans for the installation and sampling of ground water monitoring wells(AGE work plans titled Work Plan -April 1999, dated 23 April 1999 and Work Plan for Additional Well Installation-December 2000, dated 20 December 2000_). Both work plans were approved by the SJC-EHD in letters dated 29 April 1999 and 01 January 2 00 1, respectively. On 23 August 1999,one ground water monitoring well designated well MW-I was installed on-site. ' On 21 September 1999, two additional ground water monitoring wells, designated as wells MW-2 and MW-3, were installed at the site. Soil samples were collected at 5-foot intervals. 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 Exploration Drilling 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. TPH-g and BTEX compounds were not detected in the fifteen soil samples analyzed. The oxygenated fuel l ie additive MTBE was detected in three of the soil samples analyzed. The analytical results of soil samples are summarized in Tables 2 and 3. On 11 June and 12 June 2001, additional ground water monitoring wells, designated wells MW-4, MW-5 and MW-6 were installed at the site to delineate the vertical and lateral extent of the MTBE impacted ground water. Soli samples were collected at 5-foot intervals. A total of 9 soil samples were analyzed for TPH-g, BTEX and MTBE. No analytes were detected at or above laboratory reporting ' limits in the soil samples. The analytical results of soil samples are summarized in Tables 2 and 3. Monitoring wells MW-1 to MW-3 and MW-5 and MW-6 were completed as ground water ' monitoring wells using two-inch diameter PVC casing from approximately 40 feet to 60 feet bsg. Monitoring well MW-4 was completed as a 2-inch diameter depth-discrete well at the former UST dispenser and was screened from approximately 95 feet to 100 feet bsg. ' 3.9. WELL MONITORING AND SAMPLE ANALYSIS ' Water samples were collected from wells MW-1 to MW-3 during eleven ground water sampling events, and water samples were collected from wells MW-4 to MW-6 during five ground water sampling events. Ground water sampling began on 24 August 1999. Monitoring wells MW-1 through MW-6 were last monitored and sampled on 17 June 2002. The_domestic_ground water:wells were- -each-sampa during three-events. - The ground water flow direction has been inferred to be toward the northwest at an average gradient ' of 0.003 feet/feet. Figure 3 illustrates the June 2002 contoured ground water elevations. Ground water data is presented in Table 5. 1 Advanced GeoEnvironmental,Inc. 1