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RULE 2 - PERMITS <br />h, = head in alluvium <br />L = length of flow path from the mine to the alluvium <br />The flow rate from the alluvium to the mine workings is calculated below for steady-state <br />conditions. That is, the calculations assume that the cone of depression around the mine workings <br />has grown vertically upward through the overburden to the alluvium and, at the alluvium/bedrock <br />contact, has reached its maximum. This calculation does not account for the time -dependent growth <br />of the cone of depression, but rather considers only the maximum drawdown and therefore predicts <br />the maximum flow rate. The vertical hydraulic conductivity of the overburden between the mine <br />workings and the alluvium is estimated to be 10-5 ft/d, from data presented by Williams and Clark <br />(1994). The alluvial aquifer area is estimated to be approximately 3.4 x 106 ftl, or 78 acres (three <br />4000 -ft lengths of aquifer averaging 500, 250 and 100 feet wide). The head difference, h, -h,, is <br />estimated at approximately 200 feet, the average distance between the alluvium and the top of the <br />Wadge Coal. The length of the flow path, L, is approximately 200 feet, the vertical distance <br />between the mine workings and the alluvium. Thus, the calculated average inflow is: <br />C2= _' A-I;h2—h,1)/L <br />Q = 10-5ft/d - 3.4 x 101, ftZ • (200 ft) / 200 ft <br />= 34 ft}/d <br />= 0.0004 cfs <br />= 0.18 gpm <br />Table 2.05.6(2)-T1 presents a simplified water balance for PSCM based on the assumptions listed <br />above and the resultant calculations performed. The potential depletion to stream flow based on <br />Table 2.05.6(2)-T1 is 4.6 acre-feet per year. <br />Special Status Plant Species Protection/Mitigation <br />As discussed in Section 2.04.10, There are no known occurrences of designated special status plant <br />species within the planned mine disturbance areas or within the mine Permit Boundary. Given this <br />consideration, no specific protection/mitigation measures have been developed or are required. <br />RN15-01 2.05-67.1 Revision 10/17 <br />