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,. From June 1999 through June 2000, ENSR Consultants (ENSR) operated a SVE system at ., the site. Initially, ENSR extracted from VW-1 D, VW-1 S, VW-2S, VW-3, and VW-4, and injected air into air sparge well AS-1. According to ENSR, the remediation system removed over 7,000 pounds of gasoline hydrocarbons from the subsurface. In July 2000, ENSR decommissioned the system and removed the equipment from the site. On August 24, 2000, Ramage Environmental supervised the drilling of a soil boring (CPT-1A) to a depth of 100 feet through the former UST location (Figure 2). To confirm the effectiveness of remediation efforts, soil samples were collected every 10 feet. As summarized in Table 5, the soil sample results indicated that except for 560 milligrams per kilogram (mg/kg) of Total Petroleum Hydrocarbons (TPH)-as-gasoline in soil at a depth of tf approximately 10 feet below ground surface (bgs), the SVE operation remediated the vadose zone soil. The results of the confirmation soil boring are included in Ramage Environmental's Environmental Site Investigation Report, dated November 28, 2000. 1.2.4 Additional Site Characterization %aw By January 1996, a rise in the groundwater table elevation had exceeded the tops of the screen intervals in all five groundwater monitoring wells, and had entered the screen interval of the two deeper soil vapor extraction wells (VW-1 D and VW-21D). Coincidentally, from July 1995 to April 1996, groundwater samples collected on four quarterly occasions from the five monitoring wells did not contain detectable concentrations of TPH-as-gasoline. The Lr groundwater analytical results are summarized in Table 3, and the well construction and groundwater monitoring data are summarized in Table 4. In August 1996, sampling of the five original monitoring wells was discontinued and the sampling of the two deeper vapor extraction wells (VW-1 D and VW-21D)was initiated. Groundwater samples collected from VW-1 D and VW-21D contained detectable concentrations of TPH-es-gasoline (up to 12,000 µg11), benzene (up to 1,300 µgll) and methyl tertiary butyl ether MTBE u to 1,800 11 . These groundwater analytical results are � rY Y (MTBE) ( p µ9 } g yt. summarized in Table 3. On April 28, 1998, Ramage Environmental supervised the installation of two additional groundwater monitoring wells (MW-6 and MW-7). The well installations are documented in ,. Ramage Environmental's PAR-CAP, dated May 20, 1998. The monitoring well locations are shown on Figure 3, the soil sample analytical results are summarized in Table 1, the well construction details are summarized in Table 2, and the groundwater analytical results are included in Table 3. �. 6