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<br /> Pressure-grouting Wells Including Installing Mushroom Can
<br /> Wells MW-1, MW-4, MW-5, MW-6, MW-7, MW-8D, MW-9R, MW-10, MW-10A, MW-12, MW-13,
<br /> MW-14, MW-14A, MW-15R, MW-17, MW-18, MW-18D, MW-195, MW-19D MW-205, MW-20D
<br /> MW-21S, MW-21D MW-225, MW-22D MW-235,MW-23D MW-245, MW-24D, MW-255, MW-25D,
<br /> MW-27, MW-28, MW-29, MW-30, MW-31, AS-26, VEW-16, VEW-19 AND VEW-22 will be
<br /> destroyed using the pressure grout techniques described in the Workplan and reprinted here for simplicity.
<br /> "The remaining wells will be destroyed by pressure-grouting techniques using a truck-mounted, air
<br /> assist vacuum truck. Each of the wells to be pressure-grouted will be filled with Portland cement placed
<br /> with a tremie pipe. The wells will then be pressurized at approximately 20-40 pounds per square inch
<br /> (psi) until the grout level stabilizes. This process will be repeated until the grout level stabilizes and
<br /> each well is completely filled. Following pressure-grouting, the well box and concrete will be removed
<br /> and a hole at least one foot larger in diameter than the original borehole will be excavated with the
<br /> air-knife around the outside of the well casing to a depth of approximately three feet. The well casing
<br /> will then be cut off six inches above the bottom of the excavation and removed. The grout used to fill
<br /> the well will be allowed to spill into the excavation to form a one-foot-thick "cap". When the sealing
<br /> materials have set, the excavation will be backfilled with clean soil, or concrete to match the
<br /> surrounding surface."
<br /> The only exceptions to the pressure grouting methods described in the workplan pertain to wells
<br /> MW-25S and MW-25D. Due to the sensitive location of these wells directly in front of the entrance to
<br /> Chase Bank and within a slab of decoratively stamped concrete, we request that we be allowed to
<br /> pressure grout these wells and drill out the top 3 feet of the well using a limited-access hollow-stem
<br /> auger rig equipped with 8-inch-diameter augers. The rest of the procedures including sealing materials
<br /> and surface completion would remain unchanged.
<br /> The cuttings generated during these well destruction activities will be contained in a plastic-lined,
<br /> 20-cubic-yard bins, pending waste acceptance and disposal. The well casings and other miscellaneous
<br /> non-hazardous debris will either be placed in a waste receptacle or recycled.
<br /> We anticipate starting well destruction activities on January 10, 2012. In an effort to expedite
<br /> completion of the well destruction activities, we anticipate using two rigs simultaneously. Please
<br /> contact us if you have any questions concerning these revisions.
<br /> Sincerely,
<br /> GEOCON CONSULTANTS,INC. JAMES F
<br /> BRAKE
<br /> NO, 5769 •
<br /> Josh Ewert Jim Brake,PG - U t 3a I 1 e
<br /> Senior Staff Geologist Project Manager �Qp GA���
<br /> (1) Addressee
<br /> (1) Mr. R. Jay Allen, Stone Bros. and Associates
<br /> Attachments: Figure 1,Vicinity Map
<br /> Figure 2, Site Plan with Well Locations
<br /> Project No.59482-06-02 -4- January 5,2012
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