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APR. 9.2002 10~06RM TWENTYMILE CORL ENVIRONMENTRL <br />N0.871 P.5 <br />Tha collar and liner are in place and the pilot hole was completed. Shaft drilling methods were used to complete <br />the hole, The shaft was drilled to a final diameter of 42 inches and a 3 foot diameter casing Was cemented in place <br />from 5D feet below the Twentymile Sandstone to the top of the cement pad. The remainder of the casing below the <br />cement hangs in the hole, Tha hole was approximately 1200 feet in depth. The 3 foot diameter casing extended 2 <br />feet above the concrete pad. <br />A 90 degree elbow, with explosion doors, was placed on top of the 3' diameter casing. A 15' length of ducting ran <br />from the elbow to the fan location. The fan was placed on a concrete pad and a small utility building was <br />constructed to protect the fan. The building was approximately 10' x 10' and 8 - 10' in height. <br />The surfaoe collar, concrete building, and fan have been removed and associated site reclaimed. <br />Power for the fan was supplied by an overland line constructed from an existing powerline, as shown on Pigure <br />16A to toe fan, The line was installed using typical construction teehniquea. The poles were placed on <br />approximately 100 yard waters. The line is no longer required and the line and poles have been removed. <br />Given the limited surfaw disturbance TCC requested that the ventilation pad area be considered as a small <br />exemption area, not requiring the construction of a sediment pond. Umil vegetation becomes reestablished around <br />the pad a filter fence will be placed down slope of the area to trap sediment that may run off from the site. <br />EMb Ventilation 6hafts <br />Vemilatioa in the BMD is provided by two exhaust fans and one intake fan located in the NW/4 SPl4, Section 14, <br />TSN, R86W, and is identified on Maps 17A and 1SA. <br />The following activities took place at the fan site: 1) Salvaging and stockpiling available topsoil, 2) Construction <br />of road and leveling of site, 3) Construction of foundation for drilling activities, 4) Bxaavation of mud pits, 5) <br />Construction of powerlines onto the site, 6) Casing of holes, 7) Construction of buildings, and 8) Final dressing of <br />roads sad installation offence. The pad for the site is approximately 200'x600', ar 2.8 acres. <br />During construction of the pad area, topsoil was salvaged and stockpiled adjacent to the site. Approximately 24 <br />caches of topsoil was available for salvage from the 2.8 acre site, which resulted in approximately 8,700 CY of <br />topsoil placed in the adjacent stockpile, Tha topsoil salvaged from the road was windrowed to the side of the toad <br />and stockpiled. Both the stoakpile end windrowed topsoil were stabilised with the topsoil stocicpila stabilization <br />seed mixture. It should be noted that a portion of the site has been reclaimed. The remaining topsail volume is <br />presented on Tablo 49A. <br />The ventilation system required boring two shafts from the surface down into the coal seam. The exhaust return air <br />shag has a fmished inside diameter of four feet and the intake shaft has a fmished inside diameter of S feet. Both <br />holes are cased with steel. A t+eversa circulation rig was employed for the drilling ofthe two holes. A T-shaped, 2- <br />footthick reinforced concrete pad was constnteted at each site. The top of the "T" has approximate dimensions of <br />30' x 30' end contains the shaft and an 18'° diameter, 30' hole for the drill slam. The bottom of the "T" has <br />dimensions of approximately 10' x 30', Ahead frame was constructed over the bola and the holes were reamed out <br />to the final diameter of 7' sad 5.5', rospectively. Water was recycled during drilling. Two mud pits were <br />excavated to accommodate the cuttings generated during the drilling of the holes. One of the pits was 150' x 100' x <br />9' and the other one was 100° x 100' x 7'. Cuttings firm the mud pits were partially solidified and hauled to TCC's <br />solid waste disposal area. The pits era no longer required and the original excavated material was placed back into <br />the pits, <br />The holes have bees cased and fans were placed at both of the borehole locations. A total of three fans have bees <br />installed at the two locations. The retum air borehole has two fans and the intake borehole has one fan, The <br />centrifugal return fans consist of s Robinson 400 hp with exhaustlag capacity of 90,000 cubic feet par minute and a <br />hack-up Industrial Air Products (IAP) 1250 hp with exhausting oapaciry of 150,000 cubic feet per minute. <br />MR 02-178 2.05-43' 04/08/02 <br />