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• Minimizing Subsidence <br />In order to minimize the possibility of subsidence in areas where creeks, <br />pipelines, or other permanent structures overlay the mine the extraction ratio is <br />lowered to less than 50 %. This has specifically been the case underneath the <br />Palisade Water Line, Ute Water Line, and Cottonwood and Rapid Creeks. In areas <br />where more stability is needed by structures, a block of coal is left underneath the <br />structure to further minimize the possibility of subsidence. <br />Conclusion <br />The method of secondary mining at the Roadside Mines allows for a high <br />extraction while minimizing the possibility of surface disturbance. Currently this <br />method allows fora 15 ft x 100 ft pillar to be left behind yielding a extraction ratio <br />around 75%. In the upcoming year a continuous haulage section will be added and <br />the extraction ratio will be reduced to approximately 47 % with no secondary mining. <br />To comply with Stipulation 12 of the Mining and Reclamation Permit C - 81 - <br />041, two regular inspections were conducted during the 1994 year. Only two areas <br />have been located with cracks that might be the result of underground mining. <br />Surface cracks, where found, were measured and located on the attached map. <br />• Photographs were taken of the cracks over 10 West. In an effort to minimize <br />subsidence Powderhorn Coal has reduced the extraction ratio and/or left blocks of coal <br />underneath pipelines, creeks and structures. <br />• Page 4 <br />