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limited to seven 20-foot wide mains developed on 120-by-80-foot centers, resulting in <br />permanently retained 100-by-60-foot pillars. Pillar stability calculations project Ashwin/Wilson <br />safety factoring in excess of 2.0 for pillars of that size at 600 feet of overburden depth. Further, <br />in areas of the renewable resource (ands separated from the D seam by between 600 and 800 feet <br />of overburden, permanent 60-by-60-foot pillars, with Ashwin/Wilson safety factoring in excess <br />of 1.5, will be retained. In both of these areas, mining wilt be limited to development without <br />retreat extraction. Technical Revision No. 17 (TR-17) and Technical Revision No. ] 9 (TR-19) <br />address mine plan modifications to Panel B and Panel C respectively. These TR's modify the <br />pillar size and spacing scheme described above, while maintaining the required safety factors. <br />Both revisions were approved by the Division. <br />With the exception of the ruins depicted as Structure No. 27, the inventoried buildings will be <br />protected by the retention of solid coal pillazs of 300-foot radius beneath each of the potentially <br />affected buildings. <br />The operator's strain projections anticipate potential, repairable damage (non-material damage) to <br />the two existing water pipelines, the Steven's Gulch Road, assorted trails, ponds, and springs <br />within the permit area. In each case, a preferred repair methodology has been presented within <br />the Subsidence Repair Handbook portion of the permit application (Volume 3). <br />Calculations have been included to demonstrate that adequate water storage exists in the Pitkin <br />Mesa Pipeline water distribution system to assure adequate water supplies in the event of a <br />subsidence-related disruption to the pipeline. The company does not propose to mine pillars <br />beneath the Pitkin Mesa Pipeline during the five-year permit term. Only development mining of <br />main entries would occur under the pipeline and the Steven's Gulch Road within the Steven's <br />Gulch buffer zone and no subsidence is projected. BRL submitted a pipeline repair plan, signed <br />by Pitkin Mesa Pipeline Company as a condition of the approval of TR-19. <br />Technical Revision No. 22 modified the coal lease and permit boundary to the west. The new <br />permit boundary includes aeeas in the Long Draw Drainage. Upper Cabin Spring, water supply <br />for Stucker Mesa Domestic Water Company, is located in the upper reaches of this draw. BRL <br />submitted, to the Division, a signed copy of a water replacement plan agreement between BRL <br />and Stucker Mesa Domestic Water Company (see permit application, Volume I A, Section <br />2.05.6, pages 98A to D. <br />Subsidence Monitorine Proeram - <br />BRL maintains a subsidence monitoring program with three components; visual inspection, <br />wide-spaced grid subsidence monuments, and closely spaced, high-resolution subsidence <br />monuments. The visual inspection phase consists of a walk-over of the ground surface above <br />mined areas on asemi-annual frequency. [n future permit periods, when renewable resource <br />lands and structures may be undermined, pre- and post-mining inspections of structures will be <br />incorporated. The applicant also commits to daily inspection of the Steven's Gulch road, in order <br />to protect the public. <br />Monitoring stations No. 1 through No. 27 comprise awide-spaced monument grid on <br />approximately 1300-foot centers east-west and 2600-foot centers north-south. These monuments <br />provide general observations regazding the magnitude of vertical subsidence occurrences. <br />Additional wide-spaced monuments No. 70 through No. 87 will be installed above proposed <br />mine workings adjoining the old east portals. Monuments with the notations of some of the DH <br />50 series, DH-60 series and the 90 series have been installed above the underground workings at <br />38 <br />