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24HG Sample Hole(s) Project Plan Minor Revision 321 Revision Page 8 of 12 Due to the size and number of drill holes several cuttings retention options aze being analyzed. These include: ^ Piping of cutting from a mud pit located in native soil on the drill pad through a slurry pipe across MCC owned property to a temporary impoundment located on MCC owned property. Excess water could be decanted from the temporary impoundment and settled solids removed. • Use of mud pits on or near the drill pad excavated in native soil. Mud pit dimensions would be 41' x 41' x 8' to accommodate cuttings with 25% swell, the run-off associated with a 2 acre drill pad and 10 yeaz, 24-hour storm event and 1-ft of freeboard. Mudpit designs and calculations for 1.0 foot of freeboard have been previously approved by the CDMG. • Hauling cuttings off the project site and depositing in the Refuse Pile Expansion azea. As the drill pad is located at the floor of a valley, and pits shall be excavated into native soil, mud pit slope failure is not a concern. Excess run-off will be accommodated through a set of diversion ditches. Water for the drilling operations will be pumped to the drill sites from the mine dewatering polishing pond using high-pressure hose in combination with frac tanks and high-pressure pumps. Mountain Coal Company, L.L.C. owns water rights for these water resources. ll/~g~es 3~JO ""_~ said ¢ '~ DRILLING ACTIVITIES ~M~ ~'' ~ c ,,wt /t'1R -3 Z~ N'i ~~ ij0 ~ ~ ~~Q~ 1~ d f~a^- ~~J~ cost MR_3L5 red. cost, #~r~b ~ ~i'!wµ ~ TK The utilization of jet engine exhaust has been proposed as a method of rendering the mine atmosphere inert in an attempt at suppressing the thermal event. The drilling activities of the proposed jet hole will include mobilizing drill equipment to the sites and drilling and setting approximately 960 feet of 30-inch surface casing into bedrock into the B-Seam. This well will serve as the base and inlet for the jet engine exhaust being utilized in suppressing the thermal event. A depiction of the proposed well will be forwarded to the CDMG along with the typical plug and abandonment diagram. If the jet engine exhaust fails at suppressing the thermal event the six other proposed drill holes will be utilized as remote seals. The drilling activities of the proposed seals will include mobilizing drill equipment to the sites and drilling and setting approximately 1,000 feet of 17-inch surface casing into bedrock to a zone 50-ft above the coal seam. The holes will then be rotary drilled with a 14-inch diameter hole to the B-Seam. The holes will then be sampled and then a remote seal constructed with concrete in the B- Seam. A depiction of a typical completed well and remote seal will be forwarded to the CDMG along with the typical plug and abandonment diagram.