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Well Destruction Work Plan SJCEHD Case Number:2371 April 19,2012 Page 3 of 5 activities. Gregg Drilling of Martinez, California, a C57-licensed contractor, will perform the well destruction activities using a hollow-stem auger drill rig. All drilling equipment and tools shall be decontaminated prior to beginning the field activities. All reusable equipment shall be thoroughly washed with a Liquinox (or equivalent) solution and/or a heated pressure washer. Wells in which laboratory data i dicate no presence of con aminants of concern will be destroyed first. These wells includdrMW-1,✓MW-3,'MW-5, andMW-3A. Each well, which has laboratory dat indica ng thepresence o contaminants of concern will then be destroyed. These wells includeMW-2 MW-4, MW-2A, W-5A, SP-1, and VW-1. All drilling equipment will be decontaminated before and between drilling and destruction of each impacted well. A summary of analytical data for groundwater well samples is presented on Table 2. The wells will be destroyed by over-drilling the well boreholes to total depth and removing all or as much as possible of the well casing. If retrieving the casing in-whole is not possible, drilling to total depth with a larger drill bit may be necessary to destroy the well casing. Upon completion of over drilling and casing_ removal, the SJCEHD�gro ul,jnS eaor-wilLbe_notified for inspection and grouting approval. Pressurized borehole grouting will be completed with a neat-cement grout mixture consisting of approximately 5-gallons water to each 94-pound bag of Type II-N Portland cement. Pressure grouting will be completed by placing tremie rods into the borehole inside the hollow-stem augers. All pressure grouting will take place from total depth upwards. Once the boreholes have been grouted to 30 feet below ground surface (bgs) and above the current static groundwater elevation, the borehole may be grouted by gravity feed. PSC will attempt to minimize groundwater being displaced on the surface during pressure grouting by pumping water rising in the auger. Groundwater displaced to the surface during grout installation will be pumped out and/or captured and containerized in Department of Transportation (DOT) approved, 55-gallon drums. Groundwater elevation data is presented on Table 3. Surface restoration will commence after a minimum of 24-hours has passed upon completing the pressure/borehole grouting of the well boreholes. The surface restoration will then be completed using hot-mix asphalt or concrete as appropriate. Any property or vegetation damage that inadvertently occurs as part of the necessary field activities will be properly restored. PSC intends to use Osborne Concrete Coring and Stanley Engineering to complete the surface restoration activities. In some unforeseen cases, wells may need to be pressure-grouted without casing removal due to unsafe proximity to subsurface utilities. These instances would be discussed upon occurrence in the field on a case-by-case basis with SJCEHD. According to the San Joaquin County Well Standards, in some circumstances, wells may be pressure grouted with the casing left in place. If the well is to be grouted in place, the top 3 feet of the well casing shall be drilled out with an auger that is one-foot larger in diameter than the auger utilized to install the well. An additional 6-inches of soil shall be removed from around the cutoff casing to expose it. The grout rods will be placed to total depth within the well casing. Pressure grouting will continue until grout spills PSC INDUSTRIAL OUTSOURCING,LP 210 West Sand Bank Road.Columbia,IL 62236 (618)281-1543 Fax(618)281-7020