2010-06-04_PERMIT FILE - C1982056A (9)

Home Browse Search

The sinking of the shaft encompassed three distinct phases: 1.) Drilling of pilot -hole; 2.) Raise -boring or reaming - out of 48 -inch hole; and 3.) Sinking of 18 -foot diameter shaft. The first two phases are self explanatory, while the shaft sinking requires further explanation. After the hole was expanded to 48 -inch a headframe was constructed over the hole, and the process commenced to expand the hole to 18 -foot in diameter and 100 feet in depth. The process involved drilling holes from the working deck within the established boundary of the 18 -foot diameter hole and utilizing blasting materials to aid in excavation of the shaft. After the material was shot, it fell into the 48 -inch hole or was blown into the hole by a blow -pipe. The material was mucked -out from beneath the 48 -inch hole, hauled to the surface, and placed in the temporary storage location. This process was completed in 10 -foot increments until the hole was completely excavated. As the hole was excavated, the concrete liner was installed. The inside diameter of the shaft is 16 feet and the shaft was lined with concrete. Approximately 248 CY of concrete was used to construct the liner and associated collar. The concrete liner completely seals the interior of the shaft from any surface or ground water encountered during sinking of the shaft. In reference to intercepting ground water, the shaft was constructed through the Wadge Overburden, which produced a limited amount of water. The water quality is reflective of that presently encountered underground. As is noted in the annual inflow studies, the water quality has been impacted by the adjacent spoil water quality (i.e. elevated TDS). However, the quality of water was not any different than that presently encountered in the mining operation. Given the limited duration of the project and limited volume of water to be encountered, no significant water handling problems were encountered during construction of the shaft. The water that was encountered, was pumped from the mine using the existing mine dewatering system. The water was pumped to the surface at Site 109 and discharged into the mine water system or allowed to flow to the Fish Creek borehole sump. Ductwork, complete with explosion doors, was installed over the shaft. The ductwork, constructed of metal sheeting, is 62 feet in length. The ductwork was installed on a concrete pad, connecting to the fan inlet. The pad is approximately 15 x 74 x 0.5 feet thick, and required approximately 20.6 CY of concrete. The inlet evase and fan with outlet evase attached to the ductwork. The fan sets on a concrete pad that is approximately 11 x 7 x 5 feet thick, containing approximately 14 CY of concrete. The inlet evase sets on the same concrete pad as the ductwork. The outlet evase sets on four 2 x15 x 4 foot concrete footers, which required approximately 4.5 CY of concrete per • footer. _ — A utility building constructed of metal siding with insulation and metal sheeting interior was constructed to house the fan motor and the electrical components, such as breaker boxes and monitoring equipment. The building is 19 x 19 x 10 feet. The building sets on a 20 x 20 x 0.5 foot pad. Approximately 7.4 CY of concrete was used in the pad. A separate base for the motor is 5 x 4 x 6 feet, and contains approximately 4.4 CY of concrete. Two additional powerpoles were needed to provide electric service to the building. The electrical service is tied into the existing system and utilizes the nearest substation. Fish Creek Ventilation Shaft (Revised - MR07 -216) A ventilation shaft was constructed, using conventional raise - drilling techniques, in the western end of the 1 -Right Headgate to augment the existing ventilation system. The ventilation shaft and associated fan provided ventilation for the first set of longwall panels in the Western Mining District. The ventilation shaft site is shown on Map 26, Fish Creek Borehole Area Facilities and Access Road. Drilling of the shaft resulted in minimal surface disturbance. A drill pad, approximately 50 x 100 feet, was constructed. Available topsoil (approximately 12 -18 inches) was salvaged and stockpiled for future reclamation. Casing and other drilling supplies were stockpiled adjacent to the pad, however, topsoil was not salvaged from this storage area due to the temporary nature of the activity. After topsoil removal, mud pits were dug adjacent to the drillhole. A surface collar, consisting of a 10 x 10 x 2 foot concrete pad (approximately 5.5 CY of concrete) and a 5.2 foot diameter liner, extending to bedrock, was first established, and then a pilot -hole, 12.5 inches in diameter, was drilled to a depth of approximately 1,100 feet. Drilling muds were used to drill the surface collar and pilot - hole, with a concrete centering base established at the bottom of the liner. Drilling fluids and cuttings were •discharged to the pits. MR07 -216 2.05 -40 05/28/07