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w CHEVRON PIPELINE EASEMENT <br /> ENVIRONMENTAL ASSESSMENT REPORT <br /> EXECUTIVE SUMMARY <br /> Condor Earth Technologies, Inc. (Condor) conducted a limited soil and groundwater investigation <br /> adjacent to Byron Road (site), northwest of the City of Tracy, San Joaquin County, California. Soil and <br /> groundwater investigation activities were conducted at the site between June 6 and 28, and on July 24 <br /> and 25, 2001. Initially, the purpose of the work was to investigate the possible presence of petroleum <br /> hydrocarbons in soil related to an historic Chevron crude oil pipeline along Byron Road between the <br /> Alameda County line and Wicklund Road, a distance of approximately 14,400 feet. Subsequent <br /> sampling was conducted to evaluate the impact of detected petroleum hydrocarbons on construction. <br /> Condor observed the excavation of 13 trenches, seven to ten feet deep, at locations of proposed pipeline <br /> crossings of Byron Road. Condor also observed the advancement of 185 direct push borings, generally <br /> 16 or 20 feet deep, on 25-, 50-, or 100-foot centers, mostly on the south shoulder of Byron Road. No soil <br /> contamination was observed in the 13 trenches. Visual soil contamination in the form of gray green to <br /> dark brown staining of the soil was observed in 20 of the 185 borings; petroleum hydrocarbons were <br /> - detected in soil samples from 18 of these 20 borings. Petroleum hydrocarbons were detected in three <br /> additional soil samples that had no visible soil contamination. Polynuclear aromatics (PNAs) were <br /> detected in 17 of the 18 soil samples contaminated with petroleum hydrocarbons that were analyzed for <br /> _. PNAs. Contaminated soil was observed at depths ranging from 4 to 46 feet. The locations of the test pits <br /> and borings are shown on Figure 2, Appendix A. <br /> Groundwater samples were collected from 10 of the soil borings in which contaminated soil was <br /> observed and from five soil borings in an alfalfa field southeast of the intersection of Mountain House <br /> Parkway and Byron Road. Seven groundwater samples collected from the soil borings with visible <br /> contamination and one groundwater sample from a soil boring in the alfalfa field were selected for <br /> laboratory analysis. The samples were submitted and analyzed without filtration. Petroleum <br /> hydrocarbons were detected in the seven groundwater samples collected from soil borings with <br /> contaminated soil. No petroleum hydrocarbons were detected in the groundwater sample collected from <br /> the alfalfa field. PNAs were detected in all groundwater samples contaminated with petroleum <br /> hydrocarbons. A summary of laboratory test results is provided in Tables 3 through 6 of the report text. <br /> Soil and groundwater contamination by petroleum hydrocarbons in the vicinity of the historical Chevron <br /> crude oil pipeline in the areas investigated by Condor between the Alameda County line and Wicklund <br /> Road is intermittent along the alignment. Excavations below four feet in the right-of-way along the <br /> south side of Byron Road may encounter petroleum product in the soil, particularly in the locations <br /> where this investigation detected contamination. The contaminated soil is usually easy to visually <br /> identify by the gray green to dark brown stain and by the petroleum hydrocarbon odor that accompanies <br /> the staining. The presence of free product in some of the groundwater samples suggests floating product <br /> may be present in the aquifer at those sample locations. Dewatering along the south side of Byron Road <br /> will likely result in removing water containing petroleum hydrocarbons in solution, as floating product, <br /> and/or adsorbed to suspended sediment. <br /> CONDOR <br />