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14. Invasive, Non-native Species • Prevention, eazly detection, control and eradication of small noxious weed patches remain the most practical, economical and effective means of weed management. Weeds will be treated on an as needed basis. Signature of specialist: Mary Lendman 2; 27/01 NON-CRITICAL ELEMENTS Soils Since only mitrimal active surface disturbance is proposed, soil impacts from these impacts would be minimal. Subsidence could occur, which could result in some low-volume, localized soil erosion. At the time that support pillars are removed, a cumulative impact from subsidence could occur throughout the mined azea. However, in light oftherequirement in State regulations to conduct operations in such a manner as to control or prevent effects of subsidence, this is not expected to be a major concern. 2. Geolob ~ and Mineral Resources • Subsidence fractures could impact topography and surface features in the area of the proposed lease. The DMG rules require that "underground mining activities shall be planned and conducted so as to prevent subsidence from causing material damage to the surface..." Material damage is defined with respect to subsidence as changes which prevent restoration of affected Structures and with respect to renewable resource lands; changes which disrupt an aquifer, or a rechazge area to an ' aquifer, which serves as a beneficial use of water; or changes which prevent restoration of productivity for agticultural lands. In addition, National King Coal's permits to mine coal from Colorado DMG and OSM require that the company monitor subsidence on a quarterly basis. Some monitoring is also preformed periodically by the various regulating agencies (OSM and DMG) during inspections. Evidence of subsidence fractures following pillar extraction in 1979 has been noted on National • King Coal's Federal lease P-058300 in an area approximately 300 feet north of the lease boundary and on the east limb of the lease above the.westem edge of pillars that were extracted. Subsidence fractures have also been observed in the 100-acre portion of the existing mine located on Ute Mountain Ute owned land Specifically, monitoring has found that some subsidence fractures appeazed about 6 months after pillar extraction began. Cracks ran for a distance of about 200 feet where overburden depths ranged from 100 feet (drainage ways) up to 300 feet (ridge togs) and tended to follow the contour of the surface topography. They opened as much as 6 to 12 inches wide ano `~ Ieet deep wltll most evident Cracks` betng VII ui6 Sidc SiopeS- Fro St-li.°,a:`litg and Sediment • deposition reduced crack size to 1 to 2 inches within 12 months after they first appeared. There was no apparent change in ground elevation or land use. 14