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CHARTER WAY COMMINGLED PLUME—REQUEST FOR PUBLIC COMMENTS FACT SHEET
<br /> Stockton Charter Way Commingled Plume (the "site") consists of four properties with a commingled petroleum
<br /> hydrocarbon plume. The site includes former Texaco Service Station (440 West Charter Way), former ARCO Service
<br /> Station No. 2168(441 West Charter Way),Chevron Service Station Facility#92033 (508 West Charter Way),and former
<br /> Colombo/Toscana Bakery (1444 South Lincoln Street). Previous soil and groundwater investigations show petroleum
<br /> hydrocarbon contamination beneath the four sites. Cleanup had already been conducted at the former Texaco Service
<br /> Station and the former ARCO Service Station No. 2168 properties. At this time, remedial efforts will be focused at
<br /> Chevron Facility #92033 and then at former Colombo/Toscana Bakery to expedite plume cleanup. The following
<br /> summarizes site history, previous investigations,and cleanup activities at the site.
<br /> Texaco began dispensing gasoline at 440 West Charter Way in the 1960s. In 1989, petroleum hydrocarbon
<br /> contamination was found in soil and groundwater beneath the property. Between 1989 and 2007, borings and
<br /> monitoring wells were installed to determine the boundary of contamination. Total petroleum hydrocarbons as
<br /> gasoline(TPHg), benzene,and methyl tert-butyl ether(MTBE)were detected in soil at concentrations up to 3,150, 24.7,
<br /> and 1.26 milligrams per kilograms (mg/kg), respectively. TPHg, benzene, and MTBE were detected in groundwater at
<br /> concentrations up to 910,000, 51,000, and 2,400 micrograms per liter (VWL), respectively. From 1996 to 1998,
<br /> contamination was cleaned up using a soil vapor extraction (SVE)and treatment system, which removed approximately
<br /> 6,250 pounds of TPHg. Texaco transferred station operations to Shell in 1998, during which Shell closed the station.
<br /> United Gas placed new underground storage tanks(USTs)at the property and has operated the station since 1999. The
<br /> current station consists of a convenience store,car wash,four fuel dispenser islands,and four USTs.
<br /> ARCO operated former ARCO Service Station No. 2168 until 1995. During UST replacement activities in 1991,
<br /> petroleum hydrocarbon contamination was found in the soil beneath the property. From 1991 to 2005, borings and
<br /> monitoring wells were installed to determine the boundary of contamination.TPHg, benzene,and MTBE were detected
<br /> in soil at concentrations up to 12,000, 31, and 28 mg/kg, respectively. TPHg, benzene, and MTBE were detected in
<br /> groundwater at concentrations up to 180,000, 24,000, and 4,400 µg/L, respectively. Contamination was cleaned up
<br /> between 1997 and 1998 using a SVE system,which removed approximately 10,000 pounds of TPHg. Additional cleanup
<br /> activities were implemented between 2006 and 2010 using an air sparge (AS) and SVE system, which removed
<br /> approximately 4,000 pounds of TPHg. The current property owner constructed and has operated a car wash on the
<br /> property since 2005.
<br /> Chevron operated Chevron Facility#92033 until 1995,when the property was sold to a private dealer. The property is
<br /> currently an active Chevron-branded station with a convenience store, four fuel dispensers, and three USTs. In 1996,
<br /> petroleum hydrocarbon contamination was found in the soil beneath the station during UST replacement activities.
<br /> Between 1995 and 2008, soil borings and groundwater monitoring wells were installed to determine the boundary of
<br /> contamination. TPHg, benzene, and MTBE were detected in soil at concentrations up to 1,700 mg/kg, 3.4 mg/kg, and
<br /> 0.68 mg/kg, respectively. TPHg, benzene, and MTBE were detected in groundwater at concentrations up to 380,000,
<br /> 30,000, and 46,000 WL, respectively. In 2011, SVE and AS pilot tests were carried out at the station to determine a
<br /> feasible cleanup strategy. Based on the pilot test data, a full-scale SVE and AS system will be operated at Chevron
<br /> Facility#92033 as a corrective action plan remediation activity.
<br /> Former Colombo/Toscana Bakery owned and operated two gasoline USTs for fleet refueling at the property. In 1994,
<br /> the two USTs and fuel dispensers were removed. During the UST removal, petroleum hydrocarbon contamination
<br /> was found in soil beneath the property. Between 1996 and 2009, soil borings and groundwater monitoring wells
<br /> were installed to determine the extent of contamination. TPHg, benzene, and MTBE were detected in soil at
<br /> concentrations up to 13,000 mg/kg,44 mg/kg, and 1.5 mg/kg, respectively.TPHg, benzene,and MTBE were detected in
<br /> groundwater at concentrations up to 160,000, 22,000, and 3,000 gg/L, respectively. A remedial strategy similar to that
<br /> of Chevron Facility #92033 will be implemented at the former Colombo/Toscana property to clean up the
<br /> contamination. The property is currently privately owned and consists of a warehouse.
<br /> The Stockton Charter Way Commingled Plume case is under consideration for a corrective action plan by
<br /> the Regional Board. Information for the site or public comments can be submitted to Mr.James Barton by
<br /> email at(ibarton@waterboards.ca.zov), by phone at 916-464-4615-Central Valley Regional Water Quality
<br /> Control Board (CVRWQCB) at 11020 Sun Center Drive,#200, Rancho Cordova, California 9567gip/ ten
<br /> comments must be submitted to the CVRWQCB no later than 21 October 2012. KK 6ev
<br /> 2 4 2012
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