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'easibility Testing Work Plan <br /> Jimco Truck Plaza <br /> C A M B R I A 1022 Frontage Road <br /> Ripon,California <br /> May 18, 2005 <br /> September 1998: In September 1998,Walton removed three,steel,single wall USTs,(7,500 gallon <br /> and 10,000 gallon gasoline USTs and one 12,000 gallon diesel UST),four additional dispensers and <br /> associated piping. Soil samples collected by Grayland during the UST,dispensers and piping removal <br /> activities(Tl through T3,FD7 through FD 10,PL5,and PL6)confirmed that soil beneath the site had <br /> been impacted by both TPHd and TPHg. As a result, Grayland Environmental recommended that <br /> additional assessment be conducted to evaluate the extent of hydrocarbon-impacted soil and to <br /> determine if groundwater beneath the site was impacted. A total of approximately 600 tons of <br /> hydrocarbon-impacted soil was removed from the site and disposed of at Forward Landfill in <br /> Stockton, California. <br /> May to August 1999: Between May and August 1999, AG oversa the advancement of 16 soil <br /> borings (B 1 through B 16), two hydropunch borings (HP 7 and 18) and the installation of 5 <br /> groundwater monitoring wells(MW-1 through MW-5). Soil samples were collected at 5-foot intervals <br /> from each of the borings and select samples were submitted to the laboratory for analysis. Based on <br /> the analytical results, it was determined that the greatest hydrocarbon-impact to soil was in the area <br /> immediately adjacent to the former USTs at 20 ft bgs./Hydrocarbon-impacted soil appeared to be <br /> limited to a depth of approximately 30 ft bgs. Fuel oxygenates (MTBE and TBA) attenuated with <br /> depth in borings B-1 and MW-1 suggesting that the vertical extent of impacted soil did not extend far <br /> beyond 30 ft bgs. The maximum TPHg concentration was detected in the 20 foot sample from boring <br /> B5 (1,300 mg/kg) and the maximum TPHd concentration was detected in the 20 foot sample from <br /> boring B4 (8,200 mg/kg). The maximum MTBE concentration was detected in the 10 foot sample <br /> from boring B 1 (12 mg/kg) ' <br /> e111 SAS <br /> Grab groundwater samples were collected from borings B2,B5,B14,HP17,and HP18. Dissolved- <br /> phase hydrocarbons appeared to extend north of the former USTs to boring B 14.TPHg and benzene <br /> concentrations appeared to attenuate east and south of the former USTs (AGE, 1999)."Dissolved- <br /> i <br /> phase TPHd, TPHg, benzene, and MTBE were detected at maximum concentrations of 580,000; <br /> 23,000;370;and 2,700µg2,respectively,in boring B2 located on the south side of the former USTs. <br /> The highest dissolved TPHg, benzene, and MTBE concentrations from monitoring wells were <br /> detected in well MW-1,located adjacent to.the former USTs. The maximum TPHd concentration was { <br /> detected in well MW-2; located 7"'"" of the former USTs. J yyv z $ <br /> I ad jatt�nN 4� ti� <br /> lY1aH Moyr <br /> Mamh 2002: In Niaf.&A 2002,AGE oversaw the installation of groundwater monitoring well MW-9 <br /> and extraction well EW-1. Well EW-1 was installed in preparation for an aquifer pump test. Soil <br /> samples collected from the pilot boring for well MW-9 at 15,20,25,and 30 ft bgs were submitted to <br /> the laboratory for analysis. No soil samples collected from boring EW-1 were submitted to the <br /> 4 <br /> _ i, <br />