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Carbon Junction Mine <br />Fill Underdrain <br />Calculation Sheet 3 of 4 <br />100 year 24 hour Event 3.0" <br />Using the same soil cover complex number given in the Sediment <br />Pond 112 calculations (77) a maximum infiltration of 1.93" is <br />determined for the drainage area. The calculated volume of <br />infiltration from this event is <br />1100 = (1.93") (1'/12") (46.3 ac) (43,560 ft2/ac) <br />= 324,373 ft3 or 324,400 ft3 <br />These Snfiltration calculations were maximized by assuming no <br />losses to evaporation or transpiration and a minimum of surface <br />runoff. <br />The discharge capacity of the underdrain far exceeds the <br />Infiltration volume for either precipitation event. <br />Maximum Fill M scharge (Q~ <br />Should the fill become saturated, the maximum discharge from the fill <br />into the underdrain would be calculated from <br />Q WT1 where <br />F <br />QF maximum fill discharge <br />W = width of fill parallel to stream flow (underdrain) <br />T transmissivSty of fill <br />= permeability (k) x average thickness of fill <br />i = hydraulic gradient <br />= change in elevation/flow length of area <br />(taken from Sediment Pond 92 sheets) <br />