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' Pombo Ranch Facility August 17,2004 Subsurface Investigation Report& Second Quarter Groundwater Monitoring 2.4 Soil Sampling ' All soil sampling equipment was thoroughly steam-cleaned before and between sampling to prevent cross contamination. Relatively undisturbed soil samples were taken at intervals of not more than 5 feet in order to evaluate the subsurface materials. Geoprobe® samples were obtained using a Geoprobe" Systems sampler with ' plastic liners. For augured borings the soil samples were taken using a California Modified Split Spoon sampler with brass liners. A 140 pound hammer repeatedly falling 30 inches drove the sampler. The blow counts necessary to drive the ' sampler were recorded for each 6-inch interval to help evaluate the consistencies of the materials. The laboratory samples did not have head space and were immediately sealed in their liners using aluminum foil lined plastic caps. The remaining sample was removed from its liner to be used as an aide to the on-site geologist in logging the material at that depth. All soil samples were delivered, under chain of custody, to GeoAnalytical ' Laboratories, an analytical laboratory licensed by the State of California for hazardous materials work. The samples were analyzed for Total Petroleum Hydrocarbons (gasoline), BTX&E (Benzene, Toluene, Xylene, and Ethyl Benzene) and MTBE by method 8020 with confirmation by method 8260. ' 2.5 Groundwater Sampling A travel blank provided by the laboratory accompanied the sample vials from the time they were picked up from the lab to the time they were delivered back to the lab, This travel blank was not analyzed since all samples did not contain detectable contamination. 1 All sampling equipment includin the pump, bailer, cables, used by sampling personnel, were disassembled, and steam-cleaned prior to commencement of sampling. These procedures were also followed between each well, sampling point, and at the end of the sampling day. De-ionized or organic-free water (also provided by the laboratory) was then introduced into the bailer as a final stage of ' cleaning. This water was then poured into sample vials to be used as a bailer blank. ' Immediately prior to sampling, water levels.and well depth measurements were .. taken in all wells at the site. Each well was evacuated using a stainless steel bladder pump, which does not introduce air into the water column. The pH, ' temperature, and electrical conductivity of the water were monitored as the well was evacuated. A field log of well monitoring information was maintained (see Appendix C - Well Monitoring Data Sheets). Instruments calibrated to known