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-31- aquifer. The third type of inflow is also due to secondary permeability and it is the result of ground-water flow along fault zones. These fault zones may be in contact with surface aquifers or with other water bearing zones in the overburden. The streams in the North Fork area are generally fault controlled and may be a source of recharge for fault related inflows. De-watering wi]1 occur in portions of the coal seam that contain water and in the lower portions of the Barren Member; it will reach a maximum at the furthest extent of mining. Mine inflows, on the other hand, will reach a maximum sometime before the furthest extent of mining and will then taper off until equilibrium is reached. Shallow surface aquifers located close to the coal outcrop may experience some influence by the second mechanism of mine inflow, mentioned above. Calculations performed at the Mt. Gunnison mine, to estimate mine inflows, show that maximum inflows of 6.56 to 29.48 gpm, for confined and unconfined conditions respectively, may be expected in the next five years. This is exclusive of inflows from faults or from fractures in areas of shallow overburden. West Elk Coal Company used a model published by David McWorter in 1981 entitled Procedures for Predictive Anal sis of H drolo is Im acts of Surface Minin~q. Both confined an un~ine mo e s were use Y e~de tl tikes into account the size of the advancing workings, the rate of advancement, transmissivity, aquifer thickness, height of the piezometric surface above the coal seam, time in days, specific yield, and the storage coefficient. The values used in the calculations .are conservative to average. The calculated values in the McWorter model are as follows. TIME t e~of days confined coal unconfined coal gal/min gal/min 1982 365 2.48 10.42 1983 730 3.52 14.74 1984 1095 4.30 18.04 1985 1460 4.96 20.84 1986 1825 5.56 23.30 1987 2190 6.08 25.54 1988 2555 6.56 27.58 1989 2920 4.02 29.48 The projected mine inflows that were estimated at Mt. Gunnison for the year 1983 were 3.76 gpm, and for 1984, 3.97 gpm. These values are close to the values caluculated in the McWorter model for 1983, which calculated inflows of 3.52 gpm for confined conditions and 14.74 gpm for unconfined conditions. For 1984, 4.30 gpm for confined and 18.04 gpm for unconfined conditions were calculated. The actual mine inflow values, even with the flows from roof cracks and faults, are close to what would be expected for confined conditions. Additional inflows .. -_ • ;; :::~ - - -