SITE INFORMATION AND CORRESPONDENCE

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Chevron Pipeline Easement Environmental Assessment Report November 21,2001 Page 4 east of Kelso Road to approximately 200 feet east of Mountain House Parkway, and to a depth of 16 feet bgs from approximately 200 feet east of Mountain House Parkway to Wicklund Road. The depths of boreholes GP79, GP96, and GP97 were increased to determine the maximum depth of the contamination in these boreholes. Soil samples were collected from borings GPI through GP168 at approximately four-foot intervals with -- a 1.75-inch outside diameter, 4-foot long core barrel, fitted with a clean, single use, polyethylene liner. Soil samples were collected from borings GP169 through GP185 at approximately five-foot intervals with a 1.75-inch outside diameter, 5-foot long core barrel, fitted with a clean, single use, polyethylene liner. The soil sampling equipment was cleaned as described above. During the sampling, the core barrel, with polyethylene sample liners, was driven in either 4-foot or 5-foot intervals. The sample liner was extracted from the core barrel and used for geological logging and field observations. The soil samples were logged according to the Unified Soil Classification System. Geological logs containing field observations including soil type, PID measurements, and the presence of staining or odor are located in Appendix B. Soil samples were collected from each boring for laboratory analysis. The soil samples were selected for laboratory analyses based on field observations. Where contaminated soil was encountered, the soil sample was collected from the interval with contaminated soil. In borings where no contamination was observed,the soil sample was collected from the 11- to 12-foot interval. A minimum of one soil sample from each boring was cut from the polyethylene liner at the selected depth for potential laboratory analyses. The soil samples were retained, undisturbed, in the liners. The liners were sealed at the ends with Teflon® sheeting, capped, and labeled. The samples were stored in a cooler chilled with Blue Ice and delivered, under chain-of-custody procedures, to Zymax Envirotechnology, San Luis Obispo, California, for analysis. 3.4.2 Groundwater Sampling Groundwater samples were collected from all borings with field-identified contaminated soil between Mountain House Creek and Wicklund Road in which groundwater was encountered and from the borings _._ advanced in an alfalfa field southeast of the intersection of Mountain House Parkway and Byron Road. The samples were collected with a stainless steel bailer from the open borehole of all but one boring. Boring GP 156 required the installation of temporary'/4-inch PVC screen due to collapse of the borehole. The sample was collected from the screen with a stainless steel bailer. The stainless steel bailer was thoroughly cleaned before each sampling event using laboratory-grade, non-phosphate detergent and tap water and double rinsed with tap water. Groundwater samples were transferred directly from the stainless steel bailer to laboratory-supplied sample containers. The sample containers were labeled, stored in a cooler chilled with Blue Ice, and delivered, under chain-of-custody procedures, to Zymax Envirotechnology, San Luis Obispo, California, for analysis. No filtration of the samples was conducted in order to simulate the material that would potentially be encountered in construction dewatering. Consequently, the results of the water analysis reflect the total concentrations from dissolved constituents, floating product, and suspended sediment. CONDOR