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14. Invasive, Non-native Species <br />Prevention, early detection, control and eradication of small noxious weed patches remani the most <br />practical. economical and effective means of weed management. Weeds will be treated on an as <br />needed basis. <br />Signature of specialist: Maty Lendman 2/27/01 <br />NON-CRITICAL ELEMENTS <br />1. Soils <br />Since only minimal active surface disturbance is proposed, soil impacts from these impacts would <br />he minimal. Subsidence could occur, which could result in some low-volume, localized soil <br />erosion. At the time that support pillars are removed, a cumulative impact from subsidence could <br />occur throughout the mined area. However, in light of the requirement in State regulations to conduct <br />operations in such a manner as to control or prevent effects of subsidence, this is not expected to be <br />a major concern. <br />2. Geology and Mineral Resources <br />Subsidence fractures could impact topography and surface features in the area of the proposed lease. <br />The DMG rules require that "underground mining activities shall be planned and conducted so as <br />to prevent subsidence from causing material damase to the surface..." Material damage is defined <br />with respect to subsidence as changes which prevent restoration of affected structures and with <br />respect to renewable resource lands; changes which disrupt an aquifer, or a recharge area to an <br />aquifer, which serves as a beneficial use of water; or changes which prevent restoration of <br />productivity for agricultural lands. <br />In addition, National Bing Coal's pemaits to mine coal from Colorado DivtG and OSr ; require that <br />the company monitor subsidence on a quarterly basis. Some monitoring is also preformed <br />periodically by the various regulating agencies (OSM and DMG) during inspections. <br />Evidence of subsidence fractures following pillar extraction in 1979 has been noted on National <br />King Coal's Federal lease P-058300 in an area approximately 300 feet north of the lease boundary <br />and on the east limb of the lease above the western edge of pillars that were extracted. Subsidence <br />fractures have also been observed in the 100 -acre portion of the existing mine located on Ute <br />Mountain Ute owned land. Specifically, monitoring has found that some subsidence fractures <br />appeared about 6 months after pillar extraction began. Cracks ran for a distance of about 200 feet <br />where overburden depths ranged from 100 feet (drainage ways) up to 300 feet (ridge tops) and <br />tended to follow the contour of the surface topography. They opened as much as 6 to 12 inches wide <br />and 9 feet deep with most evideni cracks 'being or, the side slopes. Frost ear: ng a,.d s -°di. e.^.: <br />deposition reduced crack size to 1 to 2 inches within 12 months after they first appeared. There was <br />no apparent change in ground elevation or land use. <br />14 <br />