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projected beneath the structure. Follow-up inspection of structures will be undertaken if possible <br />subsidence damage has been reported by the owner or otherwise indicated. <br />The Ute Water Conservancy installed a waterline along the south and west perimeter of the Roadside <br />Refuse Disposal Area in the winter of 1991/1992. Although this pile has remained stable since it was <br />constructed in 1984, care was taken to protect the pipeline should any subsidence or settling occur. <br />The waterline consists of a six-inch PVC pipe braced inside a ten-inch P.I.P. encasement pipe where it <br />crosses the refuse pile. Should a rupture of the PVC pipe occur it would be contained in the P.I.P. <br />pipe and directed off the pile. <br />In 1998/99, TransColorado Gas Transmission Company (TGTC) installed a gas transmission line <br />across a portion of the permit area, within a portion of the South Portals mine area which had at one <br />time been approved for future undermining. The operator committed within the permit application to <br />develop a subsidence survey or control and mitigation plan, upon resumption of mining via the South <br />Portal. The plan will be approved by TGTC, and will be in place prior to mining within the <br />subsidence angle of draw of the gas line. An agreement between PCC and TGTC is included as <br />Appendix 20-9, in Volume 6 of the permit application. The agreement includes the provision that the <br />operator would notify TGTC six months prior to undermining of the gas transmission line. Because <br />no further mining is proposed or approved, it is not likely that this provision will be triggered. <br />Subsidence issues identified in association with PR-02, included updates to the "Man-made Features <br />Map" to include the 345KV Rifle-San Juan transmission line, a house and shop building, and an area <br />of "occasionally irrigated pastureland", all within the South Portal mining area. The house and <br />pastureland are on previously undermined areas; the powerline has not been undermined (August <br />2003). Updated subsidence impact projections were provided in response to Division requests. <br />Projected worst case impact to the occasionally irrigated pastureland is localized dewatering of ponds <br />or ditches due to subsidence cracks, which the operator has committed to repairing if they develop. <br />Foundation floor cracking to the dwelling foundation and shop floor as a result of differential settling <br />were projected worst case impacts for these structures, which were constructed over a previously <br />mined out area. <br />Worst case impacts to the power line were projected to be minor tilting of transmission towers which <br />could be repaired by shimming under the legs or replacing deformed members, which the operator <br />indicated could be done without disruption of service. Mining beneath the powerline was to be <br />limited to development mining with no secondary extraction, resulting in an extraction rate of 49%. <br />No defmitive statement from the powerline owners documenting that potential worst case subsidence <br />damage to the powerline could be repaired without disruption of service was ever submitted. <br />However, South Portal mining operations ceased in 1997, prior to extension of workings to within the <br />subsidence angle of draw associated with the powerline. No further mining within the permit area is <br />proposed or approved. The South Mine Portals were sealed in 2000, and portal entries out-by the <br />seals were backfilled in 2007. The possibility of resumption of mining under Permit C-81-041 is <br />essentially nil, and would at minimum require approval of a major permit revision. Stipulation No. 22, <br />previously attached to the permit, had required the operator to submit specific written documentation <br />from the powerline owners prior to mining within the subsidence angle of draw associated with the <br />powerline. Due to the fact that coal extraction operations have ceased and the portals have been sealed <br />and backfilled, the Division finds that Stipulation No. 22 is no longer necessary or applicable, and the <br />stipulation is being removed from the permit in conjunction with RN-5 approval. <br />Permit Revision No. 4 50 February 3, 2009