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ENVIROlvAlENTAL HEALTH-0EPARTMENT <br /> €� Donna K. Heran, R.E.H.S. SAN JOAQUIN COUNTYUnit Supervisors <br /> y Director 304 East Weber Avenue,Third Floor Carl Borgman,R.E.H.S. <br /> � Laurie A. Cotuna, R.E.H.S. Stockton,California 95202-2708 Mike Huggins, R.E.H.S., R.D.I. <br /> c:.. c • Program Manager Telephone: (209)468-3420 Douglas W.Wilson, R.E.H.S. <br /> Margaret Lagorio,R.E.H.S. <br /> Fax: (209) 464-0138 Robert McClellan, R.E.H.S. <br /> Website:www.sjgov.org/ehd/ .Jeff Carruesco, R.E.H.S. <br /> DENIS L BROWN MAR 3 1 2006 <br /> SHELL OIL PRODUCTS <br /> 20945 S WILMINGTON <br /> CARSON CA 90810-1039 <br /> RE: Former SHELL <br /> 880 Victor Road <br /> Lodi, CA <br /> San Joaquin County Environmental Health Department (EHD) has reviewed <br /> "Subsurface Investigation Report, Fourth Quarter 2005 Groundwater Monitoring <br /> Report, and Site Conceptual Model" dated February 23, 2006, prepared by <br /> Cambria for the above referenced site and has the following comments. <br /> The lateral definition of contamination in the soil is not complete since MTBE <br /> was detected in the soil sample collected at 54 feet below surface grade (bsg) <br /> when MW13 was installed and the deepest sample collected when MW10 was <br /> installed was from 50 feet bsg. The soil contamination found at 62 feet bsg in <br /> CPT1 was defined down gradient and to the southwest by the soil sample <br /> collected from CPT2 at 62 feet bsg. Soil samples from CPT1 and CPT2 from <br /> surface to 62 feet bsg were not analyzed so the lateral extent of soil <br /> contamination between 54 and 62 feet to the southwest is unknown. The <br /> concentrations found in these deep soil samples were low and were from soil <br /> beneath groundwater so the need for further definition can be evaluated as <br /> additional groundwater data is collected. <br /> The vertical extent of groundwater contamination up gradient of the source area <br /> is provided by water samples from MW 11. Since the initial water sample from <br /> MW 15, the down gradient deep screened well, had concentrations of MTBE, <br /> TBA, TPH, toluene and xylene, further sample results will be used to evaluate if <br /> this well provides the vertical down gradient extent of the contamination. <br /> The initial water samples from MW13 and MW14 had concentrations of MTBE <br /> so further sample results will be used to evaluate if these wells provide the lateral <br /> extent of contamination to the south in first encountered groundwater. <br /> The recommendation in the report to discontinue analysis for nitrate, sulfate and <br /> methane is approved. The recommendation to reduce sampling of MW6 through <br /> MW8 and MW 11 to annual sampling is also approved. EHD approves of <br />