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/XS� <br /> GEOMATRIX <br /> SOIL AND GROUNDWATER INVESTIGATION REPORT <br /> AND HUMAN HEALTH SCREENING EVALUATION <br /> Pombo Property(San Joaquin County APN 232-170-07) <br /> 1755 West II" Street <br /> Tracy, California <br /> 1.0 INTRODUCTION <br /> This report presents results of field activities performed by Geomatrix Consultants,Inc.(Geomatrix),. <br /> on behalf of Chevron Environmental Management Company(Chevron),at the Pombo Property(San <br /> Joaquin County APN 232470-07),located at 1755 West 1 l"Street in Tracy,California(the site; <br /> Figure 1). Field activities included advancing fificen soil borings and collecting soil and grab <br /> groundwater samples from selected borings. This work was performed in accordance with <br /> Geomatrix's September 9, 1999 work plan,submitted to San Joaquin County Public Health Services <br /> (SJCPHS). The purpose of this work was to gather data to assess the lateral and vertical extent of <br /> petroleum hydrocarbon-affected soil at the site;to evaluate groundwater quality at the site;and to <br /> evaluate human health risk to confirm that the presence of petroleum hydrocarbons in the site <br /> subsurface does not pose an unacceptable risk to future receptors at the site. Background information <br /> for the site,a summary of the activities performed and the results obtained,and our conclusions and <br /> recommendations regarding the site are presented below. <br /> 2.0 BACKGROUND <br /> Chevron's former Old Valley Pipeline(OVP)was located in the railroad right-of-way adjacent the <br /> northem boundary of the site. The former OVP transported heavy petroleum(crude and fuel oil) <br /> from Bakersfield to Richmond,California,from the early 1900s to the 1950s. A review of historic <br /> assessor's parcel maps and information provided by Mr.Ernie Pombo,Jr.confirm that a Mohawk <br /> gasoline station was formerly located on the site. <br /> On July 29, 1999 Earth Systems Consultants advanced four soil borings along the northern boundary <br /> of the site(EB-7 through EB-10,Figure 2). Petroleum hydrocarbon-affected soil was observed in <br /> two of these borings(EB-7 and EB-9). Soil samples were collected from borings EB-7 and EB-9 at <br /> depths of 9.0 and 14.5 feet below ground surface(bgs),respectively. No petroleum hydrocarbon- <br /> affected soil was observed in borings EB-8 and EB-10 and therefore no soil samples were collected <br /> for analysis. Total petroleum hydrocarbons quantified as crude oil,toluene,xylenes,and polynuclear <br /> aromatic hydrocarbons(PAHs)were detected in the soil samples collected from borings EB-7 and <br /> \ISF3IOEP ATA\ SAFE15MS0 65MOWMSOILGW-M.nOC I <br />