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111I1!l11111!lI1111 <br />STATE OF COLORADO <br />MINED LAND RECLAMATION DIVISION <br />Department D~ Natural ReSOUr[es <br />1313 Sherman SL. Room 215 <br />Denver. CO 60203 <br />303 8663567 <br />Fn X: 303 632-Bt06 <br />DATE: December 20, 1989 <br />T0: Jim Stevens ~~ <br />FROM: Jim Pendleton - <br />i <br />RE: New Elk Mire - T rary Abandonment Inquiry <br />J ,_~~(~ <br />~~< nu a <br />e/ As''~ <br />I\' ~O <br />\~:rr. <br />~ rB ]6 ~ <br />Foy Bomet. <br />Govemo~ <br />Fred R. Banta. <br />Dn~sion Director <br />As I understand your inquiry, you are asking whether I would have a conceptual <br />objection to allowing Wyoming Fuels to "temporarily abandon" their new Elk <br />underground coal mine. The company has maintained the mine for several years <br />in Temporary Cessation status without mining any coal. This requires the <br />operator to pump, ventilate, fire boss, and maintain the necessary equipment <br />within the mine. Wyoming Fuels would prefer to curtail the expenditure <br />necessary to maintain the mine in unfiooded and operable condition. However, <br />the company does not want to proceed with reclamation of the mine and its <br />attendant surface disturbances. Because of the significant pumping rates <br />necessary to keep the mine workings from flooding, we know that a large <br />portion of the mine's underground workings would rapidly flood. In effect, <br />the question reduces to whether or not it is realistic to assume that the <br />workings could be returned to production once flooded. There are number of <br />practical considerations involved in this question. <br />Spontaneous Combustion <br />If the New Elk had a history of spontaneous combustion problems it would not <br />be practical to allow the cessation of ventilation and fire bossing. Without <br />approved MSHA portal and shaft seals in place, the unfiooded portions of the <br />workings would be in jeopardy of combustion. However, New Elk doesn't have a <br />combustion problem, so we can discount this significant concern.' <br />Destabilization & Subsidence <br />Flooding of old abandoned mine workings commonly stimulates subsidence, <br />particularly if the workings are subsequently dewatered. The introduction of <br />water into workings increases. the pore pressure, saturates fractures, <br />accelerates expansion of swelling clays, etc. These phenomena, in turn, cause <br />degradation of the stability of pillars, ribs, roof and roof support systems. <br />As a result the underground workings commonly experience significant <br />destabilization due to flooding and subsequent dewatering. This, in turn, <br />results in surface subsidence. Joe Nugent of the Division of Mines reports <br />that New Elk does have a significant operational roof support problem, which <br />necessitates the installation of beam and post supports. He is concerned that <br />flooding would seriously compromise their roof support leading to massive <br />