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SOUTHWEST MINING DISTRICT <br />•The impacts associated with mining the coal from this District are the same as predicted above. In addition to the <br />Wadge Overburden and Twentymile Sandstone, the Fish Creek Sandstone exists over portions of the Southwest <br />Mining District. The Fish Creek Sandstone is localized in this immediate area, and is approximately 950-1,000 feet <br />above the coal seam. <br />TCC is not predicting any major impacts to the Fish Creek Sandstone. There may, however, be short-term <br />transitory impacts due to subsiding the area. This could result in lowering the Fish Creek sandstone so that any <br />associated springs would issue from a new location. This location may be at a lower elevation than the original <br />point or from a fractured zone, if present, within the area. <br />These impacts should not injure any party, and if injury does occur, TCC does have the ability to augment any <br />water loss from the unit. TCC will monitor the Fish Creek Sandstone unit during mining to detect and quantify <br />impacts, if any. The monitoring program is outlined in Exhibit 14. <br />TCC does not anticipate any impacts to the Twentymile Sandstone unit resulting from its mining in the Southwest <br />Mining District. Monitoring to date does not show any negative impacts to this unit. Likewise, there are no springs <br />on the mine property issuing from the Twentymile Sandstone, which eliminates the potential to modify the flow <br />regime of a spring. <br />Given the distance, and the depth of overburden, relative to both Fish and Foidel Creeks, no impacts are anticipated <br />to the surface water system. Please refer to the above discussion concerning surface water impacts resulting from <br />the Foidel Creek Mine. <br />Historically, TCC utilized a 25 degree draw angle to determine a required buffer distance from panels to structures <br />in order to prevent subsidence impacts. TCC, through its extensive subsidence monitoring work, has collected data <br />• which indicates that the draw angle varies from 16 to 26 degrees. Between 16 and 26 degrees, however, subsidence <br />is minimal, and no significant surface impacts can be ascertained. It is TCC's opinion that a 16 degree draw angle <br />is a more useful planning constraint. Therefore, TCC will utilize a 16 degree draw angle to determine distance <br />from panel rib -line to structure for providing adequate protection. The calculations supporting this angle of draw <br />are presented in Exhibit 7D, Revised Subsidence Predictions for Permit Revision No. 2. <br />• <br />(4) Ponds. Impoundments and Diversions <br />(a) General. A general plan and detailed denim plan for each sediment pond. water <br />impoundment and diversion proposed to be constructed within the permit area. <br />(i) Each general plan shall: <br />(A) Be prepared by, or under the direction of, and certified by a qualified <br />registered professional engineer, or by a professional geologist with assistance from experts in related fields such as <br />surveying and landscape architecture; <br />(B) Contain a description, map, prepared according to 2.10, and cross section <br />of the structure and its location: <br />(C) Contain preliminary hvdrologic and geologic information required to <br />access the hydrologic impact of the structure; <br />TR06-52 2.05-75 02/17/06 <br />