ARCHIVED REPORTS XR0008662 - Laserfiche WebLink

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' Land use in the immediate vicinity of the site is characterized by mixed commercial, residential, and light industrial Edison High School is located across Center Street to the northwest Valley Lumber is located ' immediately southwest of the site Across Second Street to the north is Alhambra Motel Residential apartments are located approximately 100 feet southeast of the site Edison High School, located at 1425 South Center Street, previously stored and dispensed fuel from two USTs one 500-gallon UST with leaded ' gasoline and one 10,000-gallon UST with diesel The USTs were removed in November 1990 Site characterization at the site was initiated iii 1991 and continues to date Petroleum hydrocarbon ' compounds consistent with those used at the site have been detected in soils and groundwater underlying the site Methyl tertiary butyl ether(MTBE)has also been detected in groundwater underlying the site ' 2.0 PREVIOUS INVESTIGATIONS ' The following is a summary of the results of previous investigations conducted at the site, as documented by EA Engineering, Science, and Technology ([EA], 1998) ' Subsurface investigations performed in 1991 at and in the immediate vicinity of the UST tank basin indicated the presence of petroleum hydrocarbons in soils and groundwater In response to the detected hydrocarbons,the three i 0,000-gallon steel USTs and associated product piping were removed in June, 1992 In November 1995, a soil vapor extraction(SVE) system comprised of five wells was installed at the site ' and operated from November 1995 to March 1996 A new SVE system comprised of two wells was installed and operated from February 1997 to March 1998 Samples of extracted soil vapor have indicated effective removal of petroleum hydrocarbons from the vadose zone underlying the site(EA, 1998) This is ' corroborated by hydrocarbon removal estimates via SVE operation, which approximate 1,551 pounds (EA, 1998) In addition, confirmation soil samples collected in August 1999 following shut down of the SVE system indicate successful removal of hydrocarbons from the vadose zone ' An area well survey performed in July 2000 indicates that the closest water supply wells to the site are two agriculturathrrigation wells (Well ID's 216 and 234) located approximately one-quarter mile south- southeast of the site(ETIC, 2000) The depth and/or perforated interval of these wells are unknown tThere are three additional water supply wells located within a one-half mile radius of the site(ETIC, 2000), however, these wells are located over 1400 ft northwest of the site and are hydraulically upgradient ' of the site The closest surface water body to the site is Mormon Slouth, located approximately 0 6 miles north of the site Duck Creek and Homestead Canal are located approximately 1 14 miles south-southeast of the site ' (EA, 1998) Data from the previous investigations have allowed for characterization of hydrogeologic conditions at the site, including definition of the extent of chemicals in soil and groundwater as summarized below