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Feasibility Test Report
<br /> C A M B R { A JIMCO Truck Plaza
<br /> 1022 Frontage Road, Ripon, California
<br /> November 16, 2005
<br /> product piping removal activities (PL-7 through PL-17) Analytical results indicated that soil
<br /> beneath the site had been nunimally impacted by TPHd FV1 I _ktL49 4 O ('11? I* I i
<br /> September 1998 In September 1998, Walton removed three, steel, single wall USTs, (7,500
<br /> gallon and 10,000 gallon gasoline USTs and one 12,000 gallon diesel UST), four additional
<br /> dispensers and associated piping On September 1, 1998, soil samples were collected by
<br /> Grayland during the UST, dispensers and piping removal activities (T1 through T3, FD7 through
<br /> FD10, PLS, and PL6) Analytical results indicated that soil beneath the site had been impacted by
<br /> both TPHd and TPHg As a result, GrayIand Environmental recommended that additional
<br /> assessment be conducted to evaluate the extent of hydrocarbon-impacted soil and to determine if
<br /> groundwater beneath the sit'$ was impacted During UST and dispenser replacement activities, a
<br /> total of approximatehy 600)to' f hydrocarbon-impacted soil was removed from the site and
<br /> disposed of at Forward�Lan in Stockton, California
<br /> May to August 1999 Between May and August 1999, AG oversaw e advancement of 16 soil
<br /> borings (B 1 through B 16), two hydropunch borings (HP1 and HP 81) and the installation of 5
<br /> groundwater monitoring wells (MW-1 through MW-5) '-Soil samples were collected at 5-foot
<br /> intervals from each of the borings and select samples were submitted to the laboratory for
<br /> analysis Based on the analytical results, it was determined that the greatest hydrocarbon-impact
<br /> to soil was in the area immediately adjacent to the former USTs at 20 ft bgs Hydrocarbon-
<br /> impacted soil appeared to be limited to a depth of approximately 30 ft bgs Fuel oxygenates
<br /> (MTBE and TBA) attenuated with depth in borings B-1 and MWA suggesting that the vertical
<br /> extent of impacted soil did not extend far beyond 30 ft bgs The maximum TPHg concentration
<br /> was detected in the 20 foot sample from boring B5 (1,300 mg/kg) and the maximum TPHd
<br /> concentration was detected in the 20 foot sample from boring B4 (8,200 mg/kg) The maximum
<br /> MTBE concentration was detected in the 10 foot sample from boring B 1 (12 mg/kg),
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<br /> Grab groundwater samples were collected from borings B2, B5, B14, HP17, and HP18
<br /> Dissolved-phase hydrocarbons appeared to extend north of the former USTs to boring B14 TPHg
<br /> and benzene concentrations appeared to attenuate east and south of the former USTs (AGE,
<br /> 1999) Dissolved-phase TPHd, TPHg, benzene, and MTBE were detected at maximum
<br /> concentrations of 580,000, 23,000, 370, and 2,900 µg/L, respectively, in boring B2 located on the
<br /> south side of the former USTs The highest dissolved TPHg, benzene, and MTBE concentrations
<br /> from monitoring wells were detected in well MW-1, located adjacent to the former USTs The
<br /> maximum TPHd concentration was detected in well MW-, , located Wrth of tie former USTs
<br /> 1 rcA2002 In 11�a�rch 12002, AGE oversaw the installation of groundwater monitoring well
<br /> MW-9 and extraction well EW-1 Well EW-1 was installed in preparation for an aquifer pump
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