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. width of the fracture zones is unknown but is estimated to be a <br />maximum of 1000 feet based on the inflows in the Sylvester Gulch <br />return. Fractures within these zones are expected to become closed <br />under sufficient overburden cover. It is estimated that below a <br />depth of about 500 feet fracture permeability within these zones is <br />low enough that vertical flow would be minimal. This assumption is <br />supported by no significant observed flows in the mine workings <br />under Lone Pine Culch where the overburden cover is about 500 feet. <br />3) From the F seam <br />Sma11 amounts of groundwater inflow are observed issuing from the F <br />seam in various parts of the mine. These inflows are probably <br />related to zones of higher fracturing within the seam itself but are <br />not thought to represent major fracture zones that could provide <br />significant vertical communication with the overlying Barren Member <br />and surface drainages. Inflows are primarily derived from storage <br />within the seam and reduce to minimal rates within a few weeks. <br />A revised model for projecting <br />developed on the basis of actual <br />more representative than previous <br />of this data. Ina "worst case" <br />mine may be considered to result <br />tude to surface water systems. <br />;roundwater inflows to the mine has been <br />observed inflows. This is believed to be <br />projections that did not have the benefit <br />scenario, all groundwater inflow into the <br />in effective depletion of the same magni- <br />• The model assumes [hat inflows will occur to the mine in areas that have <br />similar characteristics Co situations 1 and 2 described above. Situation 3 <br />was not included in the analysis as inflows from [his source constitute a <br />relatively insignificant fraction of the total inflow and probably does not <br />influence surface flows. <br />Inflow rates under both situations 1 and 2 are calculated using the simple <br />one dimensional vertical flow equation: <br />Q Kv.I.A/1440 <br />where: Q - Flow rate (gpm) <br />Kv = Average vertical permeability (gpd/sq.ft.) <br />I - Average vertical hydraulic gradient (dimensionless) <br />A - Area undermined (sq.ft) <br />For situation 1, the calculation is based on the area undermined having an <br />overburden cover less than 300 feet. For situation 2 the calculation is <br />based on the area undermined falling within the 1000 ft fracture zone width <br />defined by the major creeks and having an overburden cover of less than 500 <br />feet. The vertical hydraulic gradients for both conditions are assumed to <br />be unity which corresponds to gravity flow and is the highest gradient that <br />can possibly exist under vertical flow conditions. This value was used to <br />be conservative and conform to "worst case" projections. Values for verti- <br />cal permeability for the two cases were back-calculated from observed <br />inflow rates in the portal area and the Sylvester Gulch area respectively. <br />Values are calculated to be 0.02 gpd/sq.ft. for situation 1 and 0.1 <br />• gpd/sq.ft. for situation 2. Inflows under situation 1 are projected to <br />V-18 <br />