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- Chevron Pipeline Easement Environmental Assessment Report November 21,2001 Page 7 except in those areas where fill material had raised the ground level; at those locations, the depth of the trenches was extended to seven feet below the fill material. No petroleum hydrocarbon staining or odor was observed in any of the trench excavations. Soils encountered were predominantly clays and silts. Soil samples were collected for monitoring with a PID from the same locations as the soil samples collected for laboratory analysis. The PID samples were placed in plastic bags with a zip closure and left in the sun to warm in order to increase the volatilization of potential petroleum hydrocarbons in the sample. PID measurements of the samples ranged in concentration from 0.4 to 4.5 parts per million (ppm). Descriptions of the soils and PID measurements are presented on the trench geological logs located in Appendix B. 4.1.2 Soil Borings Wy Condor observed the advancement of 185 direct push (Geoprobe) soil borings. Soil boring locations are shown on Figures 3 through 14, located in Appendix A. Soils encountered in the borings were predominantly clays, silts, and sands. Borings advanced on the shoulder of Byron Road encountered clay and gravel fill in the upper one to three feet of the borings that appeared to be road sub--base. Soil visibly contaminated with petroleum hydrocarbons was encountered in 20 borings. Sixteen of these borings were located between 320 feet north of Mountain House Creek and Wicklund Road. No petroleum hydrocarbon contaminated soil was encountered in soil borings advanced in the vicinity of the future location of a storm water drain line in the alfalfa field southeast of the intersection of Mountain House Parkway and Byron Road. The contaminated soil was stained gray green to dark brown and had a - slight to strong petroleum hydrocarbon odor. Contaminated soil was first encountered in the borings at depths ranging from 4 to 18.5 feet. The depths of borings GP79 and GP96 were increased to determine the maximum depth of the contamination, as many of the borings were terminated before penetrating the base of the contamination(GP97 was terminated at 36 feet with contamination still present). Soil samples were collected from the sample tube next to the soil samples collected for laboratory __- analysis for monitoring with a PID. The samples monitored with a PID were put in plastic bags with a zip closure and left in the sun to warm in order to increase the volatilization of potential petroleum hydrocarbons in the sample. PID measurements of the samples from soil borings that did not encounter soil visibly contaminated with petroleum hydrocarbons ranged in concentration from 0.2 to 61 ppm. PID measurements of the samples from soil borings that did encounter soil visibly contaminated with petroleum hydrocarbons ranged upwards to 907 ppm. Geological logs with descriptions of the soils encountered in the borings are located in Appendix B. Groundwater was encountered in most borings at depths above 10 feet. Borings GP157 and GP158 were extended to a depth of 20 feet in an attempt to collect groundwater samples. Groundwater was not encountered in GP 157 at 16 feet, but groundwater was encountered after advancing the boring to 20 feet. Boring GP158 contained no groundwater after remaining open for one hour; this is the only boring that did not encounter groundwater. Groundwater samples collected from borings GP79, GP96, GP97, and GPI 17 appeared to have free product present. Dark brown oily water coated the bailer when it was withdrawn from the borings at these locations. A separate oil phase was observed in the groundwater sample containers after the samples were allowed to sit undisturbed for several minutes. %�s 4) CONDOR