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<br /> 7-Eleven Store Number 17334
<br /> Fuel Line Upgrade Soil Sampling Report
<br /> July 28, 2003
<br /> Page 2
<br /> facility did not conduct analysis for methyl-tert-butyl ether (MtBE) or other oxygenates The Shell
<br /> site, according to available information, is due to receive regulatory agency closure shortly
<br /> Groundwater monitoring and sampling has been ongoing at the Exxon site since 1987, and
<br /> conducted at the Cardlock and Shell sites since 1992 In 1988 Exxon installed a 30-foot-deep
<br /> groundwater monitoring well, MW-9, approximately 10 feet east and 10 feet south of 7-Eleven's tank
<br /> pit The depth to groundwater in MW-9 has ranged from 30 feet below ground surface (bgs) in 1990
<br /> to 20 feet bgs in April 1996
<br /> On February 20, 1997, Fluor Daniel GTI supervised the advancement of four angled and three
<br /> vertical geoprobe borings (GP-1 through GP-7) at the site (Fluor Daniel GTI, 1997) Borings GP-1
<br /> through GP-6 were drilled beneath the three 10,000-gallon USTs In addition, groundwater grab
<br /> samples were collected from borings GP-3, GP-4, and GP-7 Benzene was detected in soil sample
<br /> GP-4 @ 17 feet at a concentration of 0 0095 milligrams per kilogram (mg/kg) Total petroleum
<br /> hydrocarbons as gasoline (TPHg) was not detected above laboratory reporting limits in any of the
<br /> soil samples collected The highest MtBE concentration was reported in sample GP-1 @ 15 feet at
<br /> 0 91 mg/kg The highest dissolved benzene, TPHg, and MtBE concentrations in groundwater
<br /> samples were reported in sample GP-4 at 9,100 micrograms per liter (ug/L), 150,000 ug/L, and
<br /> • 84,000 ug/L, respectively
<br /> From September 23 through November 26, 1997, Fluor Daniel GTI supervised the drilling of five
<br /> groundwater monitoring wells (MW-1, MWAA, MW-2, MW-3, and MW-4) to depths ranging from 35
<br /> to 40 feet bgs (Figure 2, Table 3)
<br /> On August 14, 1998, monitoring wells MW-1 and MW-1A were abandoned On August 25, 1998,
<br /> approximately 200 cubic yards of soil were excavated during the removal of 3 USTs and modification
<br /> of the new tank pit Over excavation was required to accommodate the installation of two new
<br /> double-wall steel 10,000-gallon USTs Samples were collected at depths of up to 14 feet bgs
<br /> below/adjacent to the USTs and pump islands, and the product lines (Fluor Daniel GTI, 1998)
<br /> On December 17, 1998, a double-nested groundwater monitoring well (MW-5) was installed to a
<br /> depth of 40 feet bgs (Figure 2)
<br /> On April 3 and 4, 2002, soil boring SB-1 was advanced to a depth of 50 feet bgs where a grab
<br /> groundwater sample was collected with a Hydropunch sampler (IT Corporation, 2002) Two double-
<br /> nested soil vapor extraction/air sparge SVE/AS wells (SPV-1 and SPV-2) were also installed to 30
<br /> feet bgs Dissolved benzene, TPHg, and MtBE were detected in groundwater samples from SB-1 @
<br /> 50 feet bgs, at concentrations of 28 ug/L, 7,100 ug/L, and 67 ug/L, respectively Previous figures
<br /> and tables are included in Attachment A
<br /> SITE LOCATION AND FACILITY DESCRIPTION
<br /> The site is located at the northwest corner of the intersection of North Pershing Avenue and
<br /> Rosemarie Lane in Stockton, California Access to the property is provided by North Pershing
<br /> Avenue to the north and Rosemarie Lane to the west The site is located in a mixed residential and
<br /> • commercial area
<br /> File 7-Eleven/Store 17334/Reports/17334 Fuel Eine Upgrade Report doc SECOR International Incorporated
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