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§2.05 APPLICATION FOR PHRMIT FOR SIIRFACH OR IINDERGROIIND MINING ACTIVITIES - <br />MINIMIIM RHQIIIREMENTS FOR OPHRATION AND RECLAMATION PLANS. <br />• 2.05.6 Mitigation of Surface Coal Mining Operation Impacts. (Cont'd) <br />(6) (c) (i) (B) (Cont'd) <br />a subsidence factor of 0.5 with respect to National Coal Board <br />theoretical calculations. The Operator therefore believed that <br />subsidence monitoring of these stations could be reduced to an annual <br />basis and continued only to determine if any late term residual <br />subsidence occurred within these grids. A technical revision (TR-6) <br />submitted by the Operator in November 1988 and approved by the DMG <br />commits the mine to annual surveying until the DMG deems subsidence to <br />be complete. The Operator further committed to reporting the findings <br />on an annual basis. Correspondence from the DMG approving the <br />monitoring program as revised by TR-06 was included in the Subsidence <br />Appendix, Volume 3. <br />In October, 1991 technical revision 16 was submitted to the DMG by the <br />Operator. TR 16 requested that subsidence monitoring be revised with <br />respect to monument surveying. The Operator requested that surveying <br />of the monuments over the inactive portions of the Orchard Valley Mine <br />be discontinued. The request was based upon data generated during the <br />1989 and 1990 subsidence surveys which showed that the sites in <br />question had continued to remain stable (refer to 1990 Annual <br />Subsidence Report). The Operator concluded that continued periodic <br />surveying to further investigate the potential for late term residual <br />subsidence is unnecessary. <br />• During November, 2004, the Operator requested the suspension of <br />subsidence monitoring on thirteen (13) wide spaced subsidence <br />monuments, stations 14, 15, 16, 6, 81, 82, 83, 95, 99, DH-55, DH-65, <br />DH-66 and DH-68. The Operator demonstrated the thirteen monuments <br />have been stable since November, 2001, a period of three years, <br />reference TR-45. During January, 2005, the DMG approved TR-45, which <br />discontinued all wide-spaced subsidence monitoring. <br />As a result of TR-45, required subsidence monitoring is limited to the <br />Pitkin Mesa Water line subsidence monuments, PL-1 through PL-7, which <br />are monitored twice per year. Subsidence monuments are shown on Map <br />2-5. <br />Wide-spaced subsidence monuments will be installed and surveyed prior <br />to the commencement of mining in any new areas. The Operator commits <br />to future subsidence surveying consisting of annual measuring wide- <br />spaced subsidence monuments which lie within or adjacent to active <br />mine workings. Wide-spaced monument surveying shall continue on an <br />annual basis until sites are shown to be stable and approval to <br />discontinue monitoring selected sites is obtained from the DMG. <br />(C) <br />`1 `` <br />u <br />TR-45 <br />~PP2ovED <br />l~~a~o5 <br />The orientation, location and elevation of each structure within the <br />Revised 10/22/91 <br />Revised 01/04/05 <br />147 <br />