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Monitoring Well Destruction and Soil and Groundwater Investigation Report US Can—Welty Road September 24,2009 • SAIC obtained soil boring and well destruction permits from San Joaquin County Environmental Health Department(SJCEHD)prior to commencing field activities (see Appendix A). • SAIC obtained encroachment permits from San Joaquin County Department of Public Works (SJCDPW) and the California Department of Transportation (Caltrans) for work performed in Welty Road(see Appendix A). • SAIC conducted a site visit to mark boring locations for Underground Service Alert (USA), notified USA at least 48 hours in advance of field activities, and requested USA to mark underground facilities in the adjacent public ROW. • SAIC subcontracted the following industry professionals: o Cruz Brothers Locators, a private utility locator, to clear the site and proposed boring locations for any potential overhead and underground hazards and/or other potential obstacles. o RSI Drilling(a C57-licensed driller) to provide and operate Geoprobe direct-push drilling equipment, dual-tube tooling for discrete subsurface sample collection, and hollow-stem auger drilling equipment for the destruction of monitoring wells; o Flash Safety Company to prepare a traffic-control plan(approved by Caltrans and SJCDPW), and provide traffic-control measures for the boring advanced in Welty Road. 3.2 FIELD INVESTIGATION ACTIVITIES 3.2.1 Well Destruction MW-4 and MW-5 well destruction activities were completed on August 7 and 8, 2008. All well destruction activities were managed by on-site SAIC field personnel under the supervision of an SAIC California Professional Geologist. RSI Drilling was subcontracted to perform the well destructions. A representative from SJCEHD, Mr. Harlan Knoll, was the inspector during the destruction process and approved the destruction methods. MW-5 was installed March 15, 2005, and constructed of 2-inch diameter, flush-threaded, Schedule 40 polyvinyl chloride (PVC) well casing with 20 feet of 0.020-inch, machine-slotted well screen set at depths ranging between 25 to 45 feet bgs. The annular space was backfilled with Lonestar#3 sand from total depth to 2 feet above the top of the screened interval. The sand was overlain by a 2-foot bentonite seal, and the remainder of the annular space was filled with a bentonite and neat-cement mix to ground surface. Well construction details are not available for MW-4. The condition of each well was inspected prior to destruction and the total depth was measured. Each well location was cleared for utilities to 8 feet bgs by advancing three perimeter hand-auger borings. The well construction materials were over-drilled just beyond total depth with a drill rig equipped with 8.5inch-diameter, hollow-stem augers. A 1 inch-diameter tremie pipe was inserted into the borehole and cement slurry was continuously added into the open well bottom as the pipe was retracted to the ground surface. MW-4 was capped with black-dyed concrete to match the surrounding grade. MW-5 was grouted to the surface with neat cement. Information 4 from Science to Solutions