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The Division has been concerned about reactivation of these features by subsidence of the land surface resulting from coal extraction. An extensive study by Rocky Mountain Geotechnical was completed in 1986 that addressed the relationship between subsidence and the potential reactivation of slide bodies above the Bear No. 3 Mine. The study concluded that the general mass movement mechanism was small, shallow slope failures rather than large, deep failures. The report concluded that the landslide features above the Bear No. 3 Mine are currently unstable and that failures will occur regardless of subsidence effects. No subsidence effects are expected to occur in the critical toe area of any of the slide bodies. Subsidence in these areas will be controlled by split pillar removal. In 1986 a debris flow at the site displaced the Bear Mine fan. In 1993 the area of the access road immediately below the fan slid, dropping the upper road approximately six feet. It is not known if the debris flows were reactivated by mining activity. Bear Coal Company will perform subsidence monitoring quarterly and will submit reports semi-annually. One of these reports will be the Annual Subsidence Report and will be submitted by March 15 of each year. The study by Rocky Mountain Geotechnical indicates that mining of the C-Seam will result in propagation of fractures upward through the geologic section for approximately 360 feet. Strata between the C-Seam and the massive sandstone at the top of the lower coal bearing member will be rubblized to some degree. No rubblization of the overlying E- and F-Seams is expected to occur. Subsidence of the land surface is expected to a maximum of six to eight feet in the northwestern part of the mine. The permit application describes mining within the B- and C-Seams. Bear Coal Company has obtained the mineral rights to the overlying E and F coal seams, which occur from 180 feet to 410 feet above the C-Seam. Mining in these seams may significantly affect the surface and could have more significant subsidence impacts upon the existing landslide deposits. Significant consideration should be given to subsidence issues when mining of other coal seam in the area is proposed. The mining operation is in compliance with the provisions of this section with the stipulations. XVI. Concurrent Surface and Underground Mining A. This section does not apply to the Bear Coal Company permit. XVII. Operations on Alluvial Valley Floors A. Information describing alluvial valley floors (AVFs) in the study area is located in Section 2.06.8 of the Bear No. 3 permit revision application. The alluvial valley floor findings made by the Division for the Mountain Coal Company, West Elk 29