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The operator proposes to control subsidence within these renewable <br />resource lands by limiting the extraction of coal beneath these <br />potentially impacted surficial aquifers. In areas of the renewable <br />resource lands separated from the D seam by less than 600 feet, <br />extraction will be limited to seven 20-foot wide mains developed on <br />120-by-80-foot centers, resulting in permanently retained <br />100-by-60-foot pillars. Pillar stability calculations project <br />Ashwin/Wilson safety factoring in excess of 2.0 for pillars of that <br />size at 600 feet of overburden depth. Further, in areas of the <br />renewable resource lands separated from the D seam by between 600 and <br />800 feet of overburden, permanent 60-by-60-foot pillars, with <br />Ashwin/Wilson safety factoring in excess of 1.5, will be retained. In <br />both of these areas, mining will be limited to development without <br />retreat extraction. Technical Revision No. l7 (TR-l7) and Technical <br />Revision No. 19 <TR-19) address mine plan modifications to Panel B and <br />Panel C respectively. These TR's modify the pillar size and spacing <br />scheme described above, while maintaining the required safety <br />factors. Both revisions were approved by the Division. <br />With the exception of the ruins depicted as Structure No. 27, the <br />inventoried buildings will be protected by the retention of solid coal <br />pillars of~300-foot radius beneath each of the potentially affected <br />buildings. <br />The operator's strain projections anticipate potential, repairable <br />damage (non-material damage) to the two existing water pipelines, the <br />Steven's Gulch Road, assorted trails, ponds, and springs within the <br />permit area. In each case, a preferred repair methodology has been <br />presented within the.5ubsidence Repair Handbook portion of the permit <br />application (Volume 3). <br />Calculations have been included .to demonstrate that adequate. water <br />storage exists in the Pitkin Mesa Pipeline water distribution system <br />to assure adequate water supplies in the event of a subsidence-related <br />disruption to the pipeline. The company does not propose to mine <br />pillars beneath the Pitkin Mesa Pipeline during the five-year permit <br />term. Only development mining of main entries would occur under the <br />pipeline and the Steven's Gulch Road xithin the Steven's Gulch buffer <br />zone and no subsidence is projected. COVCC submitted a pipeline <br />repair plan, signed by Pitkin Mesa Pipeline Company. as a condition of <br />the approval of TR-19. <br />Technical Revision No. 22 modified the coal lease and permit boundary <br />to the west. The new permit boundary includes areas in the Long Draw <br />Drainage. Upper Cabin Spring, water supply for Stucker Mesa Domestic <br />Water Company, is located in the upper reaches of this draw. COVCC <br />submitted, to the Division, a signed copy of a water replacement plan <br />agreement between COVCC and Stucker Mesa Domestic Water Company (see <br />permit application, Volume lA, Section 2.05.6, pages 98A to 0. <br />Subsidence Monitoring Program - <br />COVCC maintains a subsidence monitoring program with three components; <br />visual inspection, wide-spaced grid subsidence monumentation, and <br />_ql_ <br />