FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Stantec Site History and Previous Investigations Former ARCO Service Station No. 2168 February 16, 2010 Underground storage tank (UST) removal activities were conducted in 1986 and 1996. A waste oil UST was formerly located in the northeastern corner of the site. The waste oil UST was reportedly removed on November 18, 1986. Two 6,000-gallon, single-walled, steel USTs; one 8,000-gallon single-walled steel UST; one 10,000-gallon, single-walled, fiberglass UST; associated product piping; and dispensers were removed in February 1996. Following UST removal, the facility was demolished. The USTs most recently contained regular, mid-grade, and supreme unleaded gasoline. Historically, the site has dispensed regular and premium leaded gasoline. Approximately 300 cubic yards of hydrocarbon-impacted soil were removed from the site during the UST and dispenser-removal activities. In March 1991, IT Corporation of Cameron Park, California performed a well survey and found one municipal well 1,800 feet north of the site. Former ARCO Service Station No. 2168 (site) operated as a gasoline retailer until 1995. Between July 1991 and October 1993, 21 soil borings were drilled at the site; seven were converted into groundwater monitoring wells (MW-1 through MW-7) and seven were converted into vapor extraction wells (VW-1 through VW-7). Between May 1995 and July 1996, six additional vapor extraction wells were installed (VW-8 through VW-13) and between July and August 2000, five additional groundwater monitoring wells were installed at the site (MW-1B, MW-1C, MW-8, MW-8B, and MW-8C). The site has been on a quarterly groundwater monitoring schedule since February 1995. Seven current and former UST facilities are in the site vicinity, and a laterally extensive co- mingled dissolved petroleum hydrocarbon plume presently encompasses the site. In May 1995, EMCON Associates of Sacramento, California prepared an off-site evaluation report identifying four potential upgradient/off-site sources of contamination to the ARCO site. These sources are: Texaco Service Station at 440 West Charter Way; Chevron Service Station at 508 West Charter Way; Transmission Store at 515 West Charter Way; and Shell Service Station at 620 West Charter Way. Two non-oil company responsible parties are south of the Texaco property and a possible additional responsible party (the City of Stockton Corporation Yard) is south of the Chevron property. All of these responsible parties are upgradient from the site and have impacted groundwater. The property owner of the site, Mr. Bill Halverson, has constructed a car wash on the site. ARCO coordinated the well destruction activities to occur during property development. ARCO also took advantage of these site activities to coordinate the installation of a remediation system. ARCO was asked by the owner to abandon monitoring well MW-4 to make way for the new car wash. Soil vapor extraction (SVE) was conducted from January 1997 through February 1998 to remediate vadose zone soil impacts. SVE was terminated after an estimated mass of approximately 10,000 pounds (approximately 1,600 gallons) of total petroleum hydrocarbons as gasoline were removed and influent benzene concentrations were less than the laboratory method reporting limits (MRL) of 0.5 milligram per cubic meter. On September 27 through 29 and October 3, 2005, vapor wells VW-2 through VW-5, VW-9, VW-12, and VW-13 as well as monitoring well MW-4 were abandoned by Woodward Drilling of 2168 Site History and Previous Investigations.doc 1