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1 Di Salvo-LalhraP <br /> Hydropunch Letter <br /> March 11,1995 <br /> Page-'3- <br /> concentration of hydrocarbons using the WET procedure are generally less than the concentrations detected in <br /> a soil sample that has been analyzed using a non-WET meth d. Therefore, assuming a worst case in which <br /> 100% of the hydrocarbon constituents detected in the soil sample collected from the floor of the over- <br /> excavation are leachable (6.2 Mg/kg toluene and 10 µg/kg xylene), the quantity of leachable hydrocarbon <br /> constituents would be less than the CRWQCB,CVR recomm nded water quality goals for toluene and xylene. <br /> PROPOSED WORK <br /> As you indicated on the telephone, the detection of .2 4g/kg toluene and 10 µg/kg kylene in the soil <br /> sample collected from the floor of the over-excavation does of confirm groundwater contamination at the site. <br /> Your conclusions are supported by the W QSA document. T ,erefore, you requested that Di Salvo Trucking <br /> proceed with the phased investigation discussed in Condor's September 27, 1994, groundwater investigation <br /> work plan and collect one (1) groundwater sample from near the east end of TK4 using a Hydropunch <br /> sampling tool. The purpose of collecting the groundwater sample is to evaluate if hydrocarbon contamination <br /> detected in the soil subsurface has leached into the shallow Nvater table at the site. <br /> Considering the above discussion regarding soil leac iability, Di Salvo Trucking requests site closure <br /> for the Lathrop site if the groundwater sample collected from the Hydropunch sampling tool contains <br /> hydrocarbon constituents at or below the CRWQCB,CVRre ommended water quality goals. Di Salvo <br /> Trucking has instructed Condor to await written correspond nce from the San Joaquin County Public Health <br /> Services, Environmental Health Division concurring with this site closure request prior to scheduling field <br /> work.. Hydropunch sampling will be scheduled as soon aspossible upon receipt of your letter of concurrence. <br /> If you have any questions or need additional information, you may contact me at (209) 668-9234. <br /> Respectfully, Reviewed by, <br /> c R. Crum Rob rt J. Job <br /> eologist Man aging C 1] ngineer <br /> cc: Charlie Lawlor, Di Salvo Trucking <br /> Elizabeth Thayer, CRWQCB <br /> Barbara Anderson, SWQCB <br /> 1SALV OILATHROPISJCPHSEH.LTR <br /> J*� CONDOR <br />