2014-04-25_PERMIT FILE - C1982056A (3)

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Raise boring methods were used to complete the ventilation shaft. The hole was reamed to a fmal diameter of 4.68 feet, and a 3-foot diameter casing was cemented in place from 50 feet below the bottom of the Twentymile Sandstone to the top of the concrete centering pad. The ventilation casing was grouted inside of t:he liner. The • remainder of the casing below the cemented section is suspended in the shaft to the total depth of approximately 1,100 feet. The 3-foot diameter casing extends 2 feet above the concrete surface pad. A 90-degree elbow, with explosion doors, was placed on top of the 3-foot diameter casing. Two 15-root lengths of ducting ran from the elbow to the fans. The fans were placed on the concrete pad and small utility tuildings were constructed to protect the fans. The buildings were approximately 10 x 10 and 12 x 12 feet respectively, and 8-10 feet in height. These structures have been removed and the 3-foot diameter shaft has been capped with a metal cover. Power for the fans was supplied from the substation constructed for the dewatering pumps. Aline ran over to the fan site, and tied into the fan. The line was hung from poles. An auxiliary fan monitoring system was installed to monitor motor and environment conditions. The line, poles, and monitoring system have been recovered. An access road was constructed linking the fan site to the access road around the dewatering ponds. The road was graveled or covered with other suitable material. A 12-inch CMP was installed in the diversion ditch on the east side of the dewatering pond and the road constructed over this culvert. Given the limited surface disturbance TCC requested that this be considered as a Small Area Exemption, not requiring sediment control. Until vegetation became reestablished around the pads, a filter fence was placed downslope of the area to trap any sediment from the site. In 2007,. the inactive Fish Creek Ventilation Shaft was modified to serve as a mine dewatering well to replace the Fish Creek South Dewatering Well. Modification work involved installation of a 220 HP submersible pump at the bottom of the shaft connected to an 8-inch diameter (maximum) steel discharge line running to the surface; installation of approximately 500 feet of buried 8-inch HDPE piping to connect the discharge to the electro- • coagulation system, water treatment system discharge, and Fish Creek/Barricade Chamber and Fish Creek/Area 1 Pit transfer pipelines; installation of three powerpoles and a 400-foot power distribution line from the electro- coagulation facilities to supply power to the pump; installation of a 10 x 10 x 8 foot pre-fabricated steel building over the ventilation shaft; and installation/connection of required control and monitoring equipment. These modifications are shown on Figure EX49G-F1 (included with electro-coagulation designs as a related :facility). All modification work occurred within the existing disturbance area, and involved no new disturbance, so drainage and sediment control provisions under the existing SAE remain applicable. Areas re-disturbed by the dewatering modification activities (trench for connecting pipeline) were stabilized by soil material replacement and reseeding. Southwest District Ventilation Borehole In 1994, an exploration hole was drilled on the prepared drill pad for the Southwest Ventilation Borehole prior to the drilling of the borehole. Access to the drill site was on the road constructed for the borehole. Mud pits were dug within the boundary of the site. The material excavated from the pits was placed adjacent to the pits within the boundary of the site. After drilling ceases the pits, once suitably dry, were backfilled with the material excavated from them. A trash pit was dug on the site, or an existing mud pit may be used to collect trash, such as paper, cans, cardboard, etc. Oily rags will not be placed in the pit. The trash pit will be backfilled when it is no longer needed. The drill hole was approximately 1,100 feet in depth and had a nominal diameter of 6.25 inches. 'Che hole was drilled with water. The water arising from the drilling containing cuttings were passed through the mud pits prior to being discharged from the site. After the hole was completed, it was logged and then grouted from the bottom • MR08-230 2.05-41 11/20/08