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1 From June 1999 through June 2000, ENSR operated a sod vapor extraction (SVE) system at the • site Initially, ENSR extracted from VW-11D, VW-1S, VW-2S, VW-3, and VW-4 After several ' months of operation, air sparging was initiated in MW-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 November 28, 2000, Ramage Environmental published Environmental Site Investigation 1 Report documenting the results of a sensitive receptor survey and the drilling of confirmation sod borings ' 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 To confirm the effectiveness of remediation efforts, sod samples were collected every 10 feet to ' a total depth of 100 feet directly beneath the former USTs The sod sample results indicated that except for 560 milligrams per kilogram (mg/kg) of 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 sod borings located approximately 20 feet northeast ' (downgradient) of the former USTs The discrete groundwater sample results indicated that the vertical extent of impacted groundwater was mostly delineated Concentrations of methyl tertiary butyl ether(MTBE) decline significantly with depth and are not present in the 125-foot ' groundwater-bearing interval Only 1,2-dichloroethane (1,2-DCA) was detected in the 125-foot groundwater sample, at a low concentration of 0 5 micrograms per liter(µg11) 1 1 . 4