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i qj 1.2.2 Remediation System -Operation and Confirmation Sampling ; From June 1999 through June 2000, ENSR operated a soil vapor extraction (SVE) system at the site. Initially, ENSR extracted from U0-1;D, VW-1 S, VW-2S, VW-3, and VW-4. After several months of operation, air sparging was initiated in MW-1. According to ENSR, the remediation 911,11t. 11j system removed over 7,000 pounds of gasoline hydrocarbons from the subsurface. In July 2000, ENSR decommissioned theisystem and removed the equipment from the site. On November 28, 2000, Ramage Environmental published Environmental Site Investigation Report documenting the results of al.sensitive receptor survey and the drilling of confirmation soil borings. 1 According to available records, three property parcels_ within 2,000-feet of the site have operating water wells. These properties include the San Joaquin Catholic Cemetery (site), St. Joseph's Hospital, and a residential!dwelling at 1821 North Hunter Street. The locations of the ' wells on the cemetery and hospital properties are shown on Figure 3. To confirm the effectiveness of,remediation efforts, soil samples were collected every 10 feet to a total depth of 100 feet directly beneath.the former USTs. The soil sample results indicated I .4'7:1!1' i F 11 that except for 560 milligrams per kilog'ra"m (mg/kg) of Total Petroleum Hydrocarbons (TPH)-as- gasoline in soil at a depth of approximately 10 feet below ground surface (bgs), the vadose zone was almost completely remediated by the SVE system. To delineate the vertical extent of impacted groundwater, discrete groundwater samples were collected at 75, 90, and 125 feet bgs,from soil borings located approximately 20 feet northeast (downgradient) of the former USTs.-Thei;discrete groundwater sample results indicated that the vertical extent of impacted groundwater was mostly delineated. Concentrations of methyl tertiary th depth and are not present in the 125-foot butyl ether (MTBE) decline significantly wi groundwater-bearing interval. Only:.1,2=d�ichloroethane (1,2-DCA) was detected in the 125-foot groundwater sample, at a low concentration of 0.5 micrograms per liter (µg11). These � � ' groundwater analytical results are sum+Imai�rized in Table 1. 5 �, i On February 7, 2001, Ramage Envirloinmental met with PHSIEHD and RWQCB to review the project. In the meeting, RWQCB requested that the extent of impacted groundwater be further defined, a downgradient monitoring:well cluster be installed, and quarterly groundwater ,..e {1 ai ! monitoring continue at the site. On February 13, 2001, Ramage Environmental requested I written regulatory directive to prepare the:!subject work plan, and on March 16, 2001, PHSIEHD documented their directive. L 5 I L -