Laserfiche WebLink
<br /> <br /> <br /> 60 C1981-041 RN7 findings <br />for future use if necessary. Monitoring of the south mains occurred until 1985, a year <br />preceding a temporary cessation that lasted until April 30, 1989. <br /> <br />In conjunction with Permit Renewal No. 3, the Division found that the past subsidence <br />monument survey monitoring had been sufficient to establish subsidence trends in the <br />Roadside South Portals mining area. Because the geology, overburden thickness and <br />coal seam extraction height remain the same as in previous mining areas that were <br />monitored, similar effects are predicted to occur, should mining resume. Visual <br />monitoring conducted twice yearly by the operator through 1998, had confirmed this <br />projection. <br /> <br />For mining under Coal Creek and Jerry Creek in the North Portal mining area, two <br />subsidence monitoring monuments were installed adjacent to Coal Creek and three <br />monuments were installed adjacent to Jerry Creek, in 1997 (see Exhibit 56, Tab 18). <br /> <br />The approved subsidence monitoring plan for the entire permit area is described <br />beginning on page 20-8 of the permit application. Because there has been no coal <br />extraction in the permit area since 1999, and no future coal extraction is proposed or <br />approved, regular annual subsidence monitoring and reporting is no longer required. <br />Subsidence inspection, documentation, and evaluation will be triggered only if <br />possible subsidence damage is reported by a surface owner or otherwise indicated. <br /> <br />The regular monitoring program that was conducted through 2001 consisted of a <br />visual surface inspection in spring and fall, to include areas to be mined within the <br />next year, and areas mined during the previous two years. Coal Creek and Jerry Creek <br />monuments were surveyed immediately prior to undermining and twice a year for two <br />years subsequent to undermining. All monitoring results, including documentation <br />and photographs of subsidence features and structures, were submitted to the Division <br />in an annual subsidence report by December 31, of each year. Any new structures <br />within the affected area not previously documented will be included in the inspection <br />schedule if new mining is projected beneath the structure. Follow-up inspection of <br />structures will be undertaken if possible subsidence damage has been reported by the <br />owner or otherwise indicated. <br /> <br />The Ute Water Conservancy installed a waterline along the south and west perimeter <br />of the Roadside Refuse Disposal Area in the winter of 1991/1992. Although this pile <br />has remained stable since it was constructed in 1984, care was taken to protect the <br />pipeline should any subsidence or settling occur. The waterline consists of a six -inch <br />PVC pipe braced inside a ten-inch P.I.P. encasement pipe where it crosses the refuse <br />pile. Should a rupture of the PVC pipe occur it would be contained in the P.I.P. pipe <br />and directed off the pile. <br /> <br />In 1998/99, TransColorado Gas Transmission Company (TGTC) installed a gas <br />transmission line across a portion of the permit area, within a portion of the South <br />Portals mine area which had at one time been approved for future undermining. The <br />operator committed within the permit application to develop a subsidence survey or