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<br />The data derived from monitoring the first room and pillar and longwall <br />panels will enable Western Fuels to make accurate predictions of <br />subsidence and strain over subsequent panels. It will be possible to make <br />accurate predictions of the timing and magnitude of any subsidence that <br />may affect the county road, so that Western Fuels can take appropriate <br />actions, i.e., repairs and traffic control. Similar predictions will also <br />be possible for panels that may produce subsidence near Red Wash. <br />Soils <br />The subsidence will cause some settling and cracking of the soils and <br />subsequent offsetting at the surface up to 5 feet high. Following natural <br />filling, resloping, and seeding this should be a minor impact. The access <br />roads and drill areas for the construction of the degas ification wells <br />will cause surface disturbance of up to 15 acres in the lease application <br />area. All roads, well areas, and associated disturbances will have to be <br />recontoured and revegetated before abandonment of the location. Some soil <br />erosion could take place until these areas are stabilized. Overall <br />impacts should not be significant. Reclamation plans will be established <br />at the time site specific drilling and mine plans are submitted. <br />Vegetation <br />Approximately 15 acres of vegetation could be removed through construction <br />of the degasification wells. After rehabilitation of the sites, the <br />overall impact should not be significant. <br />Hining's short-term effect on palustrine vegetation cannot be accurately <br />predicted. <br />/ Subsidence is not expected to noticeably affect flows in Red Wash. <br />Tension cracks which appear in the Red Wash channel would be expected to <br />rapidly fill with sediment and present no impedance to surface flows. <br />Since underlying strata are believed to be resistant to water movement, <br />accelerated percolation is not anticipated. Slumping in the channel is <br />expected to approach 4.3 feet over longwall sections on the western edge <br />of the lease, and is not expected to exceed 1.5 feet on remaining channel <br />overlying the room and pillar operation. It is presumed that differential <br />slumping over active mine areas in the LHU would temporarily impound a <br />portion of flow during high runoff events, or restrain low flows. Due to <br />this drainage's tendency to transport extremely high sediment loads during <br />runoff events (measured maximum--256,000 mg/1; WF-U Hining Permit <br />Application data), deposition would be expected to rapidly fill such <br />depressions. <br />If this proves to be the full compliment of impacts imposed on the Red <br />Wash channel, continued maintenance of current palustrine vegetation would <br />be expected. <br />However, it is possible that subsidence events could induce changes in <br />stream gradients and/or channel stability and alter the extent and <br />condition of wetland vegetation in the short-term. Elevation differences <br />at the interface between subsidence-influenced and unaffected channel <br />(northern boundary of the lease) may initiate headcutting upstream. <br /> <br />14 <br />