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' Section 3: Site Assessment Activities 3.1 Geophysical Survey The geophysical survey will be conducted by Subtronic, under the observation of ' Kennedy/Jenks staff. An estimated 2,000 linear feet of culvert is present in the 8th Street Storage Area, in addition to 11 drop inlets which were identified on a 1971 stormwater system plan, but could not be located during a field inspection (Kennedy/Jenks 2005b). ' The geophysical survey will conducted initially using a color TV inspection, which will be used to locate, inspect and record the system conditions, and location culvert connections. The TV ' inspection will be conducted by accessing the culverts through the exposed outfalls, or using drop inlets which are accessible. In the event that blockages are encountered, mapping of the culverts will be attempted using electromagnetic field induction. ' The location of culverts and drop inlets identified during the geophysical survey will be mapped on the Site base map prepared in 2004 by BKF engineers, and based on aerial photography taken on 21 October 2004. 3.2 Soil Borings A soil investigation is proposed in order to assess the potential presence of petroleum hydrocarbons in soil within the 8th Street Storage Area. Soil samples will be obtained at approximately 15 soil boring locations. The final soil boring locations will be selected based on ' the results of the geophysical survey. Advancement of the soil borings at distances less than 5 feet from the culverts will be attempted. Soil boring locations will not be placed within 25 feet of ' a track. Each soil boring will be advanced to a depth of 8 feet below ground surface (bgs). The depth to groundwater at the Site is approximately 40 feet (Kennedy/Jenks 2003). Drilling to groundwater ' is not planned as part of the current scope of work. The soil borings will be advanced using a GeoProbeTm hydraulic push/drive sampling (Direct- Push) system operated by Vironex. A 2-inch diameter steel sampling rod will be advanced in 4- foot sections, and soil samples will be recovered from acetate liners. At each 4-foot depth increment, the acetate liner will be removed from the rods, and the soil types will be logged using the Unified Soil Classification System (USCS) ASTM D-2488-93 system, in accordance ' with Kennedy/Jenks' SOG for Borehole Logging (Appendix B). Following completion of sampling activities, soil borings will be abandoned by grouting to ground surface with a neat cement. All downhole drilling equipment will be steam cleaned before use, in between borings, and prior to leaving the Site. Soil cuttings will be placed in a 55 gallon steel drum for storage. The soil cuttings will be disposed offsite, following receipt of analytical data. Two soil samples will be collected from each boring, at 4-foot intervals. Soil samples will be collected by slicing open the acetate liner, selecting a section for sampling, and then transferring the soil to laboratory supplied glass jars. Soil samples collected from each 4-foot interval will be selected based on visual and olfactory observations of petroleum hydrocarbons. The sample Soil Investigation Work Plan Page 3 ' Union Pacific Railroad Company, Stockton Railyard, Stockton, California j120031032777.16_union pacific-stockton yard109-reports4plan_soilboringltextlwp_soil_1003.doc