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Report on Additional Site Assessment 4 <br /> 7-Eleven Inc.,Store#19976 1399 N.Main St. Manteca,California March 5,2001 <br /> 3.0 ADDITIONAL SOIL AND GROUNDWATER ASSESSMENT <br /> 3.1 Permitting/Site-Specific Health and Safety Plan <br /> Appropriate permits for additional investigation were obtained from the SJCPHS. The existing <br /> site-specific Health and Safety Plan(as required by the Occupational Safety and Health Administration <br /> Standard Hazardous Waste Operations and Emergency Response guidelines 29 Code of Federal <br /> Regulations 1910.120)was used during recent activities. The document was reviewed and signed by all <br /> IT Corporation personnel and subcontractors prior to commencement of work at the site. <br /> 3.2 Soil Gas Survey <br /> Eleven soil gas survey points were installed on September 18,2000, using a truck-mounted hydraulic <br /> direct-push probe driver(Figure 2). At each location,a hollow 1-inch-diameter push-probe rod with an <br /> expandable tip was placed to a depth of 3 feet below grade. <br /> Each sample was collected by first withdrawing the probe by about 6 inches to allow exposure of the <br /> probe tip to the subsurface. Then polyethylene tubing with a threaded adapter at the end was inserted <br /> down the center of the rod. Once attached to the probe tip,the tube/adapter assembly forms a seal. One <br /> volume of soil gas was purged through each tube/adapter assembly, and then the actual soil gas <br /> samples were collected by attaching a clean, one-liter Tedlar bag to each polyethylene tube via a Teflon <br /> tube regulated by a control valve. To obtain the samples,the Tedlar bag is placed inside a sealed <br /> vacuum box; as vacuum is applied to the box,the Tedlar bag inflates with the soil gas sample. Once <br /> filled,the valve is locked and the bag sample is removed from the box for transport in an insulated <br /> container to a state-certified laboratory under legal chain-of-custody for analysis. The soil gas samples <br /> were analyzed for BTEX, MTBE, and TPH-G by EPA Methods 8020/modified 8015,and for MTBE,TBA, <br /> DIPE, ETBE,TAME, ethylene dibromide (EDB), and 1,2-dichloroethane (1,2-DCA) by EPA method 8260 <br /> (Table 1). <br /> 19976ASA <br />