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Getty Task 2 Page 29 March 1, 1983 <br />i <br />I <br />f <br />7 <br />i <br />1 <br />L <br />IL <br />L <br />(__ <br />draw down caused by penetration of the second zone reaches back to the first <br />zone, inflow will cease at the first zone and all of the inflow, i.e. the sum <br />of the values in Tables 2 and 3, will occur at the second zone. <br />Although the model provides an estimate of the vertical, downward flow <br />from the Twentymile aquifer through the marine shale and into the mine, the <br />effects of secondary permeability due to fracturing and jointing is neglected. <br />The basis for this is that the marine shale is quite thick and it is very <br />improbable that fractures canld completely penetrate this wait. In the event <br />that a zone of highly fractured shale exists, the roof inflow rates should be <br />ezpected to increase significantly. .The inflow rates would behave very much <br />like those presented in Tables 2 sad 3, large inflow rates immediately after <br />penetration of the zone with a relatively rapid decline is inflow from the <br />roof . <br />5.2 Effects of Miae on Hvdrolo¢ic Reaime <br />Daring the active operation of the mine, a majority of water currently <br />stored is the overburden aquifer will be removed. As n result, the overburden <br /> <br />aquifer will ao longer discharge water to Fish Creek. It has been estimated • <br />that this aquifer is contributing approzimately 90 gym to Fish Creek, which is <br />a relatively small portion of the 1240 gym gain estimated for Fish Creek as it <br />crosses Twentymile Park. It is improbable, therefore, that eay noticeable <br />impact to Fish Creek will occur due to the r®oval of water from the <br />overburden aquifer although s minor decrease in flow in lower Fish Creek may <br />be noticed daring eztremely low flow periods. In any event, the water that is <br />removed from the mine will probably be placed in Foidel Creek which eventually <br />drains into Trout Creek (as does Fish Creek). Because of this, Foidel Creek <br />and Trout Creek will likely experience small gains is flow during active mine <br />operation. IIpon cessation of mining, however, discharge from the aquifer will <br />be essentially zero for an extended period of time as the aquifer recovers. <br />In summary, the impacts to anrface water hydrology are ezpected to be minor <br />since the total amount of water supplied to streams in the urea by the <br />overburden aquifer is relstively small. <br />Vertical, upward leakage from the Trout Creek aquifer will cause drawdown <br />to occur in this aquifer. Although large drawdowas may occur, the amount of <br />water removed from the aquifer will probably be smell when compared to the • <br />total amount of water stored in the aquifer. Since the water levels will not <br /> <br /> <br />