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ENVIR DIME TA <br /> N L HEALTI DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> c „ ? Donna K.Heran,R.E.H.S. Unit Supervisors <br /> Director 304 East Weber Avenue, Third Floor Carl Bergman,R.E.H.S. <br /> Al Olsen,R.E.H.S. Stockton, California 95202-2708 Mike Huggins,R.E.H.S.,R.D.I. <br /> .w • Program Manager 209 468-3420 Douglas W.Wilson,R.E.H.S. <br /> Telehone: <br /> <iFOR Laurie A.Cotulla,R.E.H.S. p ( ) Margaret Lagorio,R.E.H.S. <br /> Fax: (209) 464-0138 Robert McClellon,R.E.H.S. <br /> Program Manager Mark Barcellos,R.E.H.S. <br /> DON RODGERS JUL 2 6 2005 <br /> 11900 S UNION ROAD <br /> MANTECA CA 95336 <br /> RE: The Transmission Store SITE CODE: 9321 <br /> 515 W. Charter Way <br /> Stockton CA 95206 <br /> San Joaquin County Environmental Health Department (SJC/EHD) has reviewed <br /> "Work Plan for Additional Assessment and Remedial Design for Groundwater" <br /> (Work Plan) dated June 29, 2005 submitted on your behalf by Shaw <br /> Environmental, Inc. (Shaw) and has the following comments. <br /> The Work Plan proposes to continue the investigation of the vertical and lateral <br /> extent of the petroleum hydrocarbon contamination at this site using methodology <br /> known as Ultra-Violet Induced Fluorimetry Cone Penetration Testing (UVIF-CPT), <br /> followed by the collection of grab soil and groundwater samples by direct push. <br /> Shaw proposes to install between 9 and 15 UVIF-CPT borings to collect qualitative <br /> data on the concentrations of the contamination and interpretation of subsurface <br /> soil types. The depth of these borings is proposed to be between 80 and 100 feet <br /> below surface grade (bsg); they will be located both on and offsite. The work plan <br /> also proposes analyzing water samples from the existing groundwater monitoring <br /> wells for natural attenuation parameters and for specific dissolved metals that may <br /> present a problem with certain remedial strategies. <br /> SJC/EHD approves the expanded groundwater analytical suite. SJC/EHD <br /> approves the use of UVIF-CPT at this site, but is concerned that 15 borings may <br /> be excessive. SJC/EHD recommends that careful justification be made for each <br /> boring installed. The source area needs to be defined vertically, that is, to a depth <br /> greater than 80 feet below surface grade (bsg). Historical soil data documents <br /> significant onsite contamination across the site to between 21.5 and 26.5 feet bsg, <br /> and in the source area to 40 feet bsg. <br /> The proposal to conduct an air sparge test is too vague to be approved. A <br /> previous sparge test, which used helium as a tracer, was conducted in April 2003. <br /> In correspondence dated August 18, 2003, SJC/EHD questioned the methodology <br /> used in that test and recommended that the test be redesigned to be more <br /> applicable and simulate capture of sparged hydrocarbons. Please submit an <br />