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Q�52� <br /> GEOMATriIX <br /> REPORT OF ADDITIONAL <br /> SOIL AND GROUNDWATER INVESTIGATION <br /> Pombo Property (San Joaquin County APN 232-170-07) <br /> 1755 West 11th Street <br /> Tracy, California <br /> 1.0 HTFRODUCITON <br /> This report presents results of field activities performed by Geomatrix Consultants,hrc.(Geomatrix), <br /> on behalf of Chevron Environmental Management Company(CEMC)at the Pombo Property(San <br /> Joaquin County APN 232-170-07),located at 1755 West 11th Street in Tracy,California(the site; <br /> Figure 1). The investigations described in this report occurred during two separate field efforts,one <br /> conducted in May 2000 and a second conducted in October 2000. The May 2000 investigation <br /> included advancing three borings to collect soil and grab groundwater samples at off-site locations. <br /> The October 2000 investigation included advancing four additional borings to collect soil and grab <br /> groundwater samples at off-site locations and one boring to collect a grab groundwater sample at an <br /> on-site location. This work was performed in accordance with Geomatrix's January 24 and June 29, <br /> 2000 work plans submitted to San Joaquin County Public Health Services(SJCPHS). <br /> The purpose of this work was to obtain data to assess the lateral extent of petroleum hydrocarbon <br /> affected soil and to evaluate groundwater quality on site and downgradient of the site.This report <br /> contains a summary of previous work conducted at the site, a description of the objectives of the May <br /> and October 2000 investigations,a description of the sampling activities performed in May and <br /> October 2000,the results obtained from these two investigations,and our conclusions regarding site <br /> conditions. <br /> 2.0 BACKGROUND <br /> Chevron's former Old Valley Pipeline(OVP)was located along the northern boundary ofthe site <br /> adjacent to the railroad right-of-way. The former OVP transported heavy petroleum(cmde and fuel <br /> oil)from Bakersfield to Richmond,California,from the early 1900s to the 1950s. A review of <br /> historic assessor's parcel maps and information provided by Mr. Ernie Pombo,Jr. confirm that a <br /> Mohawk gasoline station was formerly located on the site. <br /> On July 29, 1999 Earth Systems Consultants advanced four soil borings to assess whether petroleum <br /> hydrocarbon affected soil was present along the northern property boundary of the site(EB-7 through <br /> EB-10;Figure 2). Petroleum hydrocarbon-affected soil was observed in soil from borings EB-7 and <br /> \ 1`3\DE"DATA\DOC_SA E\b000S\6 7.003TOMBOSOILGWR OV00 OOC 1 <br />