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106
<br />MINE SUBSIDENCE
<br />approaches to dealing with the uncertainty
<br />inherent in the prediction of probable hydrologic
<br />consequences of subsidence. Because of the lack
<br />of definitive information with which to verify
<br />predictive assumptions, the Division has found it
<br />necessary to assume the maximum probable impacts
<br />upon hydrologic parameters, in order to prudently
<br />analyze the hydrologic consequences of
<br />subsidence. Applicants have been required to
<br />verify hydrologic consequences of subsidence
<br />through combined subsidence, ground water
<br />hydrologic and surface water hydrologic monitoring
<br />programs. Mine plans have been configured to
<br />avoid sensitive structures. Renewable resource
<br />lands, such as streams, surficial aquifers, and
<br />alluvial valley floors, have been protected
<br />through the adoption of limited extraction
<br />subsidence control plans. Fallowing the
<br />collection of site-specific subsidence and
<br />hydrologic monitoring data, it may be possible to
<br />appropriately revise mine plan configurations or
<br />increase recovery ratios.
<br />Summary and Conclusion
<br />1'he Colorado subsidence regulations were
<br />intended to represent a practical and
<br />straightforward process for the permitting of the
<br />subsidence-related aspects of underground coal
<br />mining. As of May 1, 1986, five years after the
<br />inception of the pern~anent regulatory program,
<br />thirty-seven applications have been processed.
<br />Pert`ormance of the approved subsidence control
<br />plans, as evidenced ty the programs limited
<br />exprlrience, suggest that prediction of the
<br />mechanical consequences of subsidence has been
<br />sufi'iciently accurate to preclude material
<br />subsidence damage. Flowever, the state-of-the-art
<br />of the prediction of hydrologic consequences of
<br />subsidence does not allow reliable projection of
<br />the impacts of subsidence upon the ground water
<br />and surface water hydrologic systems of permit and
<br />adjacent areas.
<br />Future research objectives should include the
<br />hydrologic consequences of subsidence, in order to
<br />improve the reliability of predictive technology.
<br />Review and reinterpretation of past research might
<br />provide valuable observations regarding the
<br />hydrologic consequences of subsidence.
<br />Observations concerning the hydrologic
<br />consequences of subsidence at active mines should
<br />be documented to contribute to advancement of the
<br />state-of-the-art.
<br />Table 1. Subsidence predictions and monitoring programs at Colorado mines
<br />Monitoring Predictive Max. Vert. Sub. Max. Draw Angle
<br />Mine Name Programs Techniques Pre ct 0 serve Pre rct~erve
<br />Pc!rmitted Mines with Acceptable Worst-Possible Subsidence Consequences
<br />Eastside GM NCB 2.13 m
<br />ME!eker Area Mines GM, V 3.35 m
<br />National King Coal V
<br />Newlin Creek M, V Abel 8 Lee 0.91 m
<br />Sunlight H
<br />Pr!rmitted Mines with Subsidence Control Plans
<br />Apex No, 2
<br />Chimney Rock (Auger•ing Plan)
<br />Deserado
<br />Eagle No. 5
<br />Foidel Creek
<br />Golden Eagle (Maxwf!11)
<br />Hawks Nest Mines
<br />Mt. Gunnison No. 1
<br />New Elk (Allen)
<br />North Thompson Creek
<br />Orchard Valley
<br />Red Canyon
<br /> S Hunt 1.71 m
<br />GM, V, S 0.79 m
<br />GM, S NCB 7.89 m
<br />GM, V, S NCB, [Obs. 110'b
<br />GM, V, S Ashwin & Wilson 7.52 m
<br />GM, V, S Peng 0.98 m
<br />M, V
<br />GM NCB, Ashwin &
<br />Wilson
<br />GM, V, S Peng
<br />GM, V NCB
<br />GM, Y, S NCB, Ashwin &
<br />Wilson
<br />M, S Obert 8 Duvall
<br />0.79 m
<br />1. Abel, J.F., jr. and Lee, F.T., 1980,
<br />"Lithologic Controls on Subsidence", Soc, of
<br />Mining Engineers 1982 Fall Meeting, Minneapolis
<br />Minn „ Preprint Number 80-314, Oct., 16 pp.
<br />2. Ashwin, D.P. and Wilson, A.H., 1972, "Research
<br />Into the Determination of Pillar Size". The
<br />Mining Engineer, Vol. 131, Part 9, June, pp.
<br />~~~~~
<br />3. British National Coal Board (NCB), 1975,
<br />"Subsidence Engineers Handbook", Production
<br />De artment, London, 111 pp.
<br />4, unt, .R., 1979, "Characterization of
<br />Subsidence Profiles Over Room-and-Pillar Coal
<br />Mines in Illinois". Proceedings of the
<br />Illinois Mining Institute, S£ nr~ n~ual-Fleeting,
<br />PP• ~J-6 -
<br />5. Obert, L. and Duvall, W,I., 1967, "Rock i
<br />Mechanics and the Design of Structures in
<br />Ro~c~7~Tdi e'T~3ons, ~ o~rk,~bS pp.
<br />6.~ e~ng, S.S., 1978, "Coal Mine Ground Control",
<br />John Wiley 8 Sons, ew or pp. -
<br />References
<br />25.0°
<br />16.0°
<br />20.0°
<br />25,0°
<br />0.15 m 20.5°
<br />35.0°
<br />of Pred.][Obs.= Pre d. - 1°]3
<br />22,5°
<br />30,0°
<br />0.44 m 30,0°
<br />20, 5°
<br />0.12 m 30.0°
<br />1.98 m 45,0°
<br />1.31 m 20.5°
<br />0.0 m 0.0 m 20.5°
<br />
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