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qeasibility Testing Work Plan <br /> Jimco Truck Plaza <br /> C A M B R I A 1022 Frontage Road <br /> Ripon, California <br />} <br /> May 18, 2005 <br /> 3.0 PREVIOUS INVESTIGATIONS <br /> Below is the chronology of site assessment, feasibility testing and interim remedial activities at the <br /> site. Historical soil and groundwater analytical data are presented in Tables 1 and 2,respectively. <br /> i <br /> October 1996: In October 1996, AGE drilled 3 borings (B-14 through B-16) along the southern <br /> border of the site. These borings were part of AGE's delineation of a hydrocarbon plume originating <br /> from the adjacent Ripon Farm Services property, located south of the site. TEC Accutite collected <br /> split soil and grab groundwater samples on behalf of Olympian Oil. Totaletroleum hydrocarbons as <br /> 1D 14020'= vX.gyi.�t►�1 ; �/s Q/pp'= /160!11.4114* vrn <br /> diesel TPHd was detected only in borin 15 at 20 ft b s at a concentration of 1 milk rams per <br /> (TPHd) Y g� g , C g p 4�y�ot <br /> kilogram(mg/kg). Total petroleum hydrocarbons as gasoline(TP H )was detected in alit borings <br /> at concentrations ranging from 0 81 to jW mg/kg. Benzene wasNtected in�borings 13+5 ind-B-T6--at <br /> .co ging from_U40S-to-0-H—mg/kg. Grab groundwater samples were collected from <br /> borings B14 and Bo. Dissolved-phase TPHd, TPHg, and benzene were detected at maximum <br /> 400 ,loo MU <br /> concentrations of 1, 6 . <br /> 60; 12;$00; and,'micrograms per liter (µg2), respectively, in boring B14 <br /> located near the southern site boundary. tit 0 i <br /> May 1998: In May 1998, AGE oversaw the installation of groundwater monitoring wells MW-6, <br /> MW-7,and MW-8.These wells were intended to assess the extent of a hydrocarbon plume related to <br /> the adjacent Ripon Farm Services property located south of the site. A 20 ft bgs soil sample was <br /> collected from each of the well pilot borings. TPHd was detected in each sample and concentrations <br /> ranged from 1.1 to 490 mg/kg. The highest TPHd concentration detected was from the pilot boring <br /> for well MW-6. No benzene was detected in any of the soil samples. The only sample analyzed for <br /> i <br /> TPHg was from the pilot boring for well MW-7 and TPHg was detected at a concentration of 6 mg/kg. <br /> June 1998: In June 1998,Walton Engineering(Walton)of West Sacramento,California removed six <br /> fuel dispenser islands and associated piping. Soil samples collected by Grayland Environmental <br /> (Grayland)of Davis,California during the fuel dispenser and product piping removal activities(FD 1 <br /> I <br /> through FD6,PL through PL4)confirmed that soil beneath the site had been impacted primarily by <br /> TPHd, and TPHg to a lesser extent. <br /> July 1998: In July 1998, Walton removed old product piping and installed a new UST, ten <br /> dispensers, and new product piping to connect the new dispensers with the new UST and existing <br /> ASTs. Soil samples collected by Grayland during the product piping removal activities(PL-7 through <br /> .PL-7 r )7)confirmed that soil beneath the site had been minimally impacted by TPHd. p <br /> "INT i �'9� SPL-11 Inas cab "d wr +80w,ll <br /> f <br /> 3 <br /> i <br />