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Well Abandonment and Soil and Groundwater Investigation Work Plan US Can-Welty Road September 2007 • Update the site-specific Health and Safety Plan; • Update the site-specific Journey Management Plan; • Conduct a site visit to mark boring locations for Underground Service Alert, which will locate underground facilities in the adjacent public right of way; and • Subcontract Cruz Brothers Locators,a private utility locator,to identify any potential overhead and underground utility hazards. 3.2 WATER WELL SEARCH A new search is not necessary,because DWR files were searched in April 2004. 3.3 FIELD INVESTIGATION ACTIVITIES Borings will be hand cleared to 8 feet bgs,prior to drilling. SAIC will contract a California-licensed(C- 57)driller to operate a hollow-stem auger drilling system to properly abandon monitoring wells MW-3 and MW-4. A truck-mounted,GeoProbe®direct-push rig or a hollow-stem auger will be used to advance the following 11 delineation borings(Figure 3): • "A",`B","C", "D",and"K"to delineate the extent of affected media around MW-2 and GMX-8; • "E"to delineate the extent of affected media up gradient of GMX-3; • "F"and"G"to explore a potential source of affected media along the TAOC pipeline up gradient of SB-17; • "H"and"I"to delineate the extent of affected groundwater down gradient of SB-17; • "J"to explore a potential source of affected media along the OVP up gradient of SB-17. Monitoring Well Abandonment Monitoring well MW-5 will be destroyed in accordance with SJCEHD guidelines. Monitoring wells MW-3 and MW4 will also be destroyed if laboratory analytical results of a final sampling event satisfy the well destruction criteria described in Section 2.5. For the well destructions,casings and filter packs will be over-drilled to total depths of 50 and 46 feet bgs,respectively,using a truck-mounted drill rig equipped with 10-inch-diameter,hollow-stem augers. All material will be removed from the well. The well borings will be backfilled with neat cement to surface grade using a tremmie pipe and pump. SAIC will notify SJCEHD and the RWQCB of the well abandonment a minimum of 48 hours in advance. Construction details of these wells are provided in Appendix A. Collection of Soil Samples Soil borings will be continuously cored with the GeoProbe®Dual Tube sampling system,or with core barrels of a hollow-stem auger rig. The sampler will contain a plastic acetate liner that retains a relatively undisturbed soil core. The soil samples selected for analysis will be cut from the plastic liners,sealed with Teflon tape and plastic end caps, labeled with identifying information,and stored in a pre-chilled ice-chest for transportation to the laboratory. Each borehole will be logged for lithological content using the Unified Soil Classification System as a guide including color,relative moisture content, and other observable distinguishing characteristics(i.e., color changes,debris,rootlets,or odor). SAIC will utilize a photoionization detector(PID)to screen soil for the presence of volatile organic compounds. Lithologic observations,PID screening results,and other observations will be recorded on field logs. If affected soil is observed,soil samples will be collected from within and from beneath the affected zone to determine the magnitude of the vertical extent of the COCl in soil. If affected soil is not present in a boring,then soil samples will be collected at a depth where affected soil was observed in adjacent 8 from Sc ecce to Sounoms