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KOPPEL�STOCKTON TERMINAL MONITORING WELL ABANDONMENT AND CONSTRUCTION WORK PLAN 4.0 Well Abandonment A hollow stem auger rig with 10-inch inner diameter augers will be used to overdrill the borehole for the monitoring well. A well destruction permit will be obtained from San Joaquin County prior to drilling. A San Joaquin County Environmental Health Department grout inspector will be onsite to oversee overdrilling and abandonment. Well destruction and abandonment will be performed in accordance with San Joaquin County Well Standards,Ordinance Code Section 9-1115.6 (http://www.sj o� v.org/ehd/docs/Well%2OStandards. tIA The boring will be abandoned by completely backfilling the cleared borehole with neat cement.The grout will consist of clean water mixed with Type I or II Portland cement(or equivalent)and bentonite(3 to 5 percent by weight)to help reduce shrinkage.The cement grout will consist of not more than two (2) parts by weight of sand and one (1)part by weight of cement(per bag of cement) to 5 to 7 gallons of potable water. The grout will be brought with 2 feet of ground surface and the borehole will be backfilled with 2 feet of surrounding material. Three of the monitoring wells (Monitoring Wells KP-5S,KP-10S and KP-BG-1) are shallow wells (22 feet below ground surface [bgs])and Monitoring Well KP-5D is a deep well (61 feet bgs). Monitoring Well Pair KP-5S and KP-51)is buried and now located in the middle of a newly developed dirt access road on BNSF property. Monitoring Well KP-10S was never located during the last sampling event in 2009,therefore it is assumed to be buried and damaged. Uncovering,overdrilling,and sealing will be completed in approximately two days. 5.0 Well Construction and Development The proposed well construction schematic for KP-10S-R is shown on Figure 2.The monitoring well will be constructed with a 4-inch diameter 0.020-inch slot size polyvinyl chloride casing.The borehole will be advanced to a total depth of 22 bgs and the screen placed from approximately 6 to 21 feet bgs.A 15-foot screen interval is proposed to include both the water table(groundwater depth has ranged from 6.0 to 14.4 feet below top of casing in nearby well KP-2)and the screen intervals of other shallow-screened monitoring wells.The screened interval may be modified based on the geology and depth to water observed in the field and the ground surface elevation relative to Koppel.The screen will be packed with No.3 sand from the bottom of the well to approximately 1 foot above the screen. Approximately 1 foot of transition sand (No. 60 or equivalent) will be placed on top of the filter pack. Bentonite pellets will be used to form a seal at least 2 feet thick above the filter pack.The pellets will be hydrated and allowed to set for at least 20 minutes prior to grouting. The remaining annular space will be filled to the surface with cement-bentonite grout. Grout will be poured into the shallow borehole.The type of surface completion will be confirmed with the property owner before well installation. For this work plan,it is assumed the surface completion will consist of a 12-inch diameter,above ground stovepipe surface complete set in concrete.The well will be locked with standard Master locks.Following completion,the top of casing and ground surface elevations will be surveyed to the 1988 North American Vertical Datum. RDD1102300006(CLR4507.DOCX) 4 ESfIC91fM2BPP00