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West Elk Mine <br />• Protection of Hydrologic Balance - 2.05.6(3)(a)(i) <br />The surface effects of mining on the hydrologic balance in the SOD azea aze anticipated to be <br />minimal. Section 2.05.6 (6) in this document describes at length the anticipated impacts to the <br />ground surface resulting from mining activities in the SOD. It is acknowledged throughout this <br />permit that numerous landslides and slumps are present throughout the MCC permit azea and <br />these features generally move in response to saturation by precipitation events. Monitoring plans <br />included in 2.05.6 (6) describe how MCC will observe these features for effects due to mining <br />related activities. <br />If, through the monitoring activities, it is determined that mine-related subsidence causes new <br />movement of landslides and slumps MCC will mitigate damages to the impacted drainages. For <br />example, if stream courses aze blocked by mining induced slide movement, MCC will use hand <br />tools or appropriate heavy equipment to reopen affected channels. The necessary permits to <br />perform such work will be obtained prior to performing mitigation. Other mitigation could <br />include the placement of straw bale dikes or silt fences below slide azeas to reduce sediment <br />loading. Stream chammels and ditches will be repaired using bentonite, bentonite/soil mixes, or <br />available soil to fill cracks if they occur in the channel bottoms and divert water. Culverts could <br />also be used to temporarily maintain stream flows until other appropriate mitigation can be <br />implemented. <br />Areas that aze devoid of vegetation as a result of slump or landslide movement related to mine <br />• activities will be revegetated. Applications of appropriate seed mixes and planting of seedlings <br />will be performed as needed. The reseeded azeas may be covered with erosion control matting if <br />needed. Application of straw mulch may also be appropriate in selected azeas. The seed mixes <br />and seedlings used will be appropriate for the area disturbed and approved by the governing <br />agencies before application or planting. <br />Protection of Public Parks and Historic Places - 2.05.6(4) <br />Operations at the West Elk Mine aze not located near public parks or historic places; therefore, this <br />section does not apply. <br />Surface Mining Near Underground Mining - 2.05.6 (5) <br />There are no surface mining operations proposed neaz the West Elk Mine. <br />Subsidence Survey. Subsidence Monitoring and Subsidence Control Plan - 2.05.6 (6) (a-f- <br />The extraction of the B Seam coal in the Box Canyon permit area, the B and E Seams in the Apache <br />Rocks pemut azea, and the E Seam mining in the South of Divide permit revision area will be <br />completed using longwall mining methods. The resulting disequilibrium due to longwall mining <br />may result in surface subsidence, dependent on a number ofinter-related factors. As stated by Peng <br />in Surface Subsidence Engineering (1992), "When total extraction is used, it produces a lazge void <br />• in the coal seam and disturbs the equilibrium conditions of the surrounding rock strata. The rock <br />strata bend downwazd while the floor heaves. When the excavated area (gob) expands to a <br />1.05-92 Revised November 2004 PRIG <br />