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• control and regrading of roads as required. The possible effects of <br />subsidence relative to roads will, therefore, be temporary, can be readily <br />addressed using common construction practices and will not result in any <br />significant long-term impacts. <br />The refuse disposal area is underlain primarily by the main entries, <br />however, some portions of the refuse area are underlain by sub-mains. <br />Mining under the main entries is to be accomplished in two (2) phases. <br />The first phase, which has been completed in many areas, consisted of <br />development mining. No evidence of subsidence has been observed by EFCI <br />in areas where the development phase of mining has been completed. The <br />second phase consists of pillar extraction or retreat mining which will <br />approximate extraction conditions for longwall mining. This phase is <br />expected to result in some subsidence, impacts of which are discussed <br />under the subtitle, "Subsidence Control Plan" later in this section. <br />Impacts to the refuse pile are expected to be minimal as detailed in the <br />RMG report contained in Exhibit 23, Subsidence Information. <br />• Freshwater Pond No. 3 is a partially incised pond located above the main <br />entries. The location of this structure is outside the limits of planned <br />retreat mining. Subsidence resulting from development extraction is <br />expected to produce very little subsidence or surface cracking during the <br />life of the pond and the potential for leakage from the pond is <br />effectively addressed by the existing pond lining. <br />Sedimentation Pond No.4 is located outside the limits of mining. Although <br />the expected angle of draw, predicted by RMG to be between 20 to 25 <br />degrees, could extend to the pond area, the magnitude of subsidence will <br />not be significant and is not expected to result in any impacts to this <br />structure. <br />The possibility exists for power poles and substations within angle of <br />draw limits to be unevenly influenced. Subsidence may reduce electrical <br />clearance due to tilting, and/or vertical displacement. Resulting strains <br />. in the powerlines would, in the opinion of officials from Southern <br />Colorado Power who maintain the line, exceed safe limits for the lines. <br />This could possibly result in material damage requiring immediate <br />2.05.6-58 <br />.~- <br />