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T��r k.) P.O. Box 576981-6981 <br /> M.J. Kloberdanz & %sociates Modesto, California 95357 <br /> Environmental Assessment Phone: (209) 557-8186 <br /> Fax: (209) 577-8158 <br /> December 3, 2002 <br /> Ms. Lori Duncan, Senior REHS <br /> Mr. Nuel C. Henderson Jr., R.G. <br /> LOP / Site Mitigation Unit IV <br /> San Joaquin County Environmental Health Department ULU 10 z002 <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 —2708 -:'a'-viKuN..IAENT HEALTH <br /> PERMIT/SERVICES <br /> RE: McDowell and Davis Towing, 1360 Escalon Ave, Escalon, CA 95320 — Site # 1486 <br /> f This letter is being submitted in response to the San Joaquin County Environmental <br /> !, Health Department (SJCEHD) review letter dated October 24, 2002. The review letter <br /> requested the following that the model be reevaluated using more restrictive site-specific <br /> information. In addition, a description of the residual calculation was requested. <br /> The model input parameters have been examined and the SJCEHD suggested values for <br /> soil porosity and groundwater gradient used in the modeling. Groundwater contamination <br /> concentrations from the November 2002 monitoring event were used to represent current <br /> groundwater conditions. An error in the concentration values of xylene concentrations <br /> used in the mass calculation and in the modeling was discovered. The Table of laboratory <br /> results of the January 2000 site investigation, shown below, has a typographic error. The <br /> correct xylene value, as shown on the laboratory report is 400,000 ug/kg not 4000000 <br /> ug/kg as shown below. <br /> LaboratorX Soil Sample Results 1/28/00 <br /> f Sample I.D. Gasoline I Benzene Toluene E-Benzene Xylenes MTBE 8260 <br />' B-1-20' ND ND ND ND ND ND NA <br /> B-1-25' ND ND ND ND ND ND NA <br /> B-1-35' ND ND ND ND ND ND NA <br /> B-1-40' ND ND ND ND ND ND ND <br /> B-2-15' 2600 mg/kg 860 120000 510000 8000 NA <br /> B-2-25' ND ND 11 ND 48 36 NA <br /> B-2-35' ND ND ND ND ND ND NA <br /> B-2-45' ND ND ND ND ND ND ND <br /> B-3-15' ND ND ND ND ND ND NA <br /> B-3-20' ND ND ND ND ND ND ND <br /> B-4-15' ND ND ND ND ND ND NA <br /> B-4-20' ND ND ND ND ND ND ND <br />