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Soil-Vapor Sampling and Analysis Work Plan Former Shell Central Valley Crude-Oil Pipelines August 15,2007 Machado Property(Neighborhood B)Parcel 209-060-08 Page 2 of 4 detectable up to 36,000 and 80,000 milligrams per kilogram (mg/kg). Groundwater concentrations ranged from non-detectable up to 15,000 and 21,000 micrograms per liter(µg/L). Borings advanced up gradient and down gradient of the pipeline alignment did not contain detectable TPHd or TPHc,or contained very low concentrations of these constituents. Benzene,toluene,ethylbenzene,and total xylenes(BTEX)compounds were detected in soil and groundwater in borings advanced along the pipeline alignment,but were not detected in samples from borings advanced up gradient or down gradient of the pipeline alignment. Along the pipeline alignment, BTEX compounds were detected at concentrations from non-detectable up to 0.17 mg/kg(toluene), 2.4 mg/kg(ethylbenzene),and 8.7 mg/kg(total xylenes)in soil. Benzene was not detected in soil samples across the entire site. Groundwater concentrations of TPHd and TPHc were detected at concentrations ranging from 75 to 21,000 µg/L(area 139). Separate-phase hydrocarbons(SPH)were observed in one groundwater sample (area 132). BTEX compounds were detected at low concentrations in groundwater samples,with benzene detected to a maximum of 0.42 µg/L(area 136)and remaining BTEX compounds detected to a maximum of 30 µg/L of toluene(area 132). OBJECTIVE The objective of the proposed work is the collection and analytical testing of soil-vapor samples to evaluate potential risk to indoor air following construction at the site. SCOPE OF WORK All soil-vapor samples will be collected along the alignment of the pipelines at the areas previously excavated and backfilled. This proposed scope of work will be implemented in three phases: pre-field preparation,field work, and reporting. The following sections describe SAIC's pre-field and field procedures for the collection of soil-vapor samples. PRE-FIELD PREPARATION SAIC will obtain necessary soil boring permits for the proposed drilling activities from the San Joaquin County Environmental Health Department(SJCEHD)prior to fieldwork. In addition, SAIC will provide the SJCEHD with a copy of the existing site access agreements between Shell and the property owners. SAIC will mark proposed boring locations and the site boundaries with white paint and notify Underground Service Alert at least 48 hours prior to commencement of any subsurface fieldwork,as required by law. SAIC will also prepare a site-specific Health and Safety Plan that describes the activities to be performed, which will be kept on site during field work. FIELD WORK During the initial investigation at the site, impacted soil was noted in a total of 12 areas(B-1 through B-12),and impacted groundwater was noted at or above 1,000 pg/L in four areas of excavation(132,B3, B6,and B-9). Based on the presence of impacted soil (prior to remediation)and/or groundwater,soil- vapor samples will be collected from six areas: B2,B3,B6,B8,B9,and B 12(Figures 2 through 4). SAIC plans to collect soil-vapor samples 1 foot below the base of the excavation areas where soil impacts were observed. See the following table for proposed sampling depths: