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monitoring drill pads and access road construction are needed, they would utilize the same locations as those used for MDWs. The most common subsidence related impacts are likely to be surface tension fractures, which will be more evident on hard -competent sandstone outcroppings, although tension fractures may also extend into colluvium, alluvium, and weathered bedrock. The majority of movement associated with subsidence over panels is usually complete within 12 months after longwall mining. Within the lease mod areas, the average mining height of coal is expected to be 10.9 feet. As a general rule of thumb, through the mining process the overburden is subsided 70% of the mining height. So in the modification area, it is expected that the land may subside approximately 7-8 ft. The effect on topography is also related to the amount of overburden (more cover, less subsidence), and the modification area ranges in overburden from 800 ft — 2,200 ft (avg. 1200 ft). Subsidence and hydrology monitoring may require placement of monitoring devices on the land surface. These may include small subsidence monuments, survey markers, stream gages, flumes, etc. Access to the facilities may require motorized vehicles that would use the system of existing roads or trails. At the leasing stage, it is not possible to locate site-specific areas where potential surface uses may occur, therefore, the above surface use and disturbance estimations will be used to aid the cumulative impact analysis for this proposal. If surface uses are proposed during the life of the proposed lease modification, then the site-specific proposals will be made based on the surface use stipulations on the lease and evaluated under NEPA and/or the State mine permitting regulations, under their own merits at the time they are proposed. Lease Stipulations There are two existing stipulations attached to the parent leases for this project which are relevant for this analysis, and which will be carried over into the new modification area if the project is approved, with wording slightly modified to reflect changes in Management, specifically the 2008 Southern Rockies Lynx Management Direction. Those stipulations are: To comply with the GMUG Forest Plan 2008 amendment, the following special constraints will apply if surface use on the lease is proposed in lynx habitat: a. Winter access will be limited to designated routes. Sunset Lease Modification Biological Assessment 6