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52.05 APPLICATION FOR PERMIT FOR SURFACE OR UNDERGROUND MINING ACTIDITIES -- <br />MINIMUM REQIIIREMENTS FOR OPERATION AND RECLAMATION PLANS. <br />2.05.6 MitigaCion of Surface Coal Mining Operation Impacts. (Cont'd.1 <br />(3) (b) (iv) (Cont'd.) <br />~~~"y <br />• <br />fractures which developed in response to un- <br />dermining a single panel would be closed by <br />undermining an adjacent panel (Dunrud, 1976). <br />The existing and proposed monitoring program, <br />including interval parameters and duration, <br />may be found in Section 2.04,7. <br />The Mesaverde groundwater resource, as de- <br />scribed in Section 2.04,7, may be impacted in <br />the following manner, Perched, litfiologically <br />controlled water occurrences encountered with- <br />in the mine workings will be drained by three <br />discrete zones of subsidence impact upon the <br />overburden scrota. These zones are: zone o£ <br />primary caving where the strata is completely <br />disintegrated; zone of secondary caving where <br />a network of horizontal and vertical cracks <br />develop; and zone of bed separation where sep- <br />aration occurs primarily along pre-existing <br />bedding planes. The changes in permeability <br />are substantial in the first two zones and the <br />thickness of these zones typically reached 3 <br />to 3.5 times the thickness of extraction (Rop- <br />ski and Lama, 1982), <br />The thickness of the [hird zone, where changes <br />in permeability due to subsidence can occur is <br />estimated betcoeen 30T (Wardell, 1976) and <br />33.7T (Williamson, 1978) where "T" equals the <br />thickness of the fully extracted coal seam, <br />This increase of permeability in the zones af- <br />fected by subsidence is estimated to range be- <br />tween 10 and 230 times the pre-mining values <br />(Whittaker, et, al. 1979, Sikora, 1976, and <br />Neale and Whittaker, 1979), although Whittaker <br />(1979) reports this increase is temporary and <br />there is an indication of increasing consoli- <br />dation after caving. Owili-Eger (1983) re- <br />ports an increase of 5 times in transmissivity <br />of overlying aquifers £rom longwall mining in <br />the Appalachian Coal Basin, which may be more <br />realistic in Orchard Valley Mine conditions. <br />• Added 12/Z6/84 <br />Revised 10/01/87 <br />131 <br />