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" t <br /> Wright <br /> Environmental <br /> Services, Inc. <br /> 2395 East Pescadero Avenue <br /> Tracy,CA 95304 <br /> December 10, 2007 <br /> Project No. 4509-T <br /> City of Tracy <br /> 520 South Tracy Boulevard <br /> Tracy, California 95376 <br /> Attn.: Mr. Paul Verma <br /> Re: Limited Phase II Site Investigation <br /> Groundwater Monitoring Well Installation and Sampling Workplan <br /> Delta Disposal, 99 Sixth Street,Tracy, CA PHS EHD Site Code#2183 <br /> Dear Mr. Verma, <br /> Wright Environmental Services, Inca (Wright)has prepared this workplan on behalf of City of <br /> Tracy (property owner) for the above referenced site. This work is in response to letter dated <br /> October 17, 2007 from the San Joaquin Public Health Services Environmental Health Division <br /> (SJC/EHD) for additional site assessment. The City and SJC/EHD held a meeting regarding.the <br /> next step in the assessment process and the `following workplan has been prepared for the <br /> groundwater monitoring well installation and monitoring well sampling for the site. <br /> 1.0 Background <br /> Two underground fuel storage tanks were removed in 1985 from a location that later became a <br /> portion of Sixth Street. The two tanks (one 350-gallon diesel and one 500-gallon gasoline) <br /> locations were excavated in May 1990 and soil samples collected at the west end of the <br /> excavation at that time showed 18,000 parts per million (ppm) of Total petroleum Hydrocarbons <br /> as Diesel (TPHD). As a result of that information, SJC/EHD requested additional site <br /> assessment. Three exploratory borings were drilled and sampled by Wright around the former <br /> underground tank pits in Sixth Street in February 2003. Soil boring samples collected in <br /> February 2003 showed that contaminants contained TPHG and TPHD in soil samples near the <br /> capillary fringe, with the highest values in B-2. Groundwater samples from the borings showed <br /> TPHG and TPHD in Borings B-2 and B-3. These samples together with the inferred northerly <br /> groundwater flow direction indicate that a dissolved plume has migrated to and is assumed to <br /> have crossed the Delta Disposal property line. <br /> Pagel of 5 <br />