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N August 6, 2014 Page 4 of 10 Reference: Well Destruction Work Plan ARCO No. 2130 • VW-9 and VW-12 are located within 14- 15 inches of live electrical lines that provide service to the site . Stantec is prepared to perform lock out tag out of the lines, but given the close proximity to spinning augers, Stantec is recommending that that these wells be pressure grouted with a variance. • MW-6 was installed in 1992 and is now located immediately adjacent to an underground electrical line/box in the right-of-way. This utility service location had to be installed post- well installation and cannot be locked out or tagged out . There are also utility and overhead signage limitations. These fifteen wells ( MW-5, MW-6, MW-13, MW-16, MW-20, AS-2, AS-3, VW-3, VW-6, VW-8 through VW- 12, and MS-3A/B) are recommended for pressure-grouting with a county variance of a mushroom cap only within the diameter of the borehole. Prior to pressure-grouting activities, the well casing will be inspected for obstructions; if obstructions are found, they will be removed prior to grouting . With County concurrence, these 15 wells will be destroyed by pressure grouting, which consists of filling the well and filter pack with neat cement grout through a tremie pipe from total depth to top of well casing . Grout will be allowed to settle and then topped off before pressure is applied to the wells at 25 pounds per square inch for ten minutes . Following pressure grouting, the top 3 feet will be cleared with an airknife and vacuum truck, creating a hole at least the some width as the auger originally used to install the well (8 to 12 inches) . In addition, the well box, concrete apron, and well casing from 2.5 feet below ground surface to grade will be removed . After the well box, concrete apron, and length of well casing are removed, grout sealant will be placed to spill out of the top of the well casing to form a mushroom cap seal to 2 feet bgs. The remaining void will be filled with native soil or engineered fill and the surface will be completed to match the existing grade. The four wells (AS-2, AS-3, VW-6 and VW- 11 ) located in the tank pit have a very large vault/well box around them and will be left in place to prevent sparks that could be generated if removal was attempted . A profile diagram of the top three feet of these wells is included in Attachment C . Waste Management All investigation derived waste, including soil and groundwater (if present) from the well and soil vapor probe destruction activities will be stored on-site in Department of Transportation- approved 55-gallon drums pending proper disposal. All waste will be transported and disposed of at an appropriate State-certified disposal facility. Design with community in mind