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Realistic Discharge <br />Roughly 422 acres of irrigated land will be constructed in reclamation of the New Horizon #2 mine. <br />An analysis of these areas separately will provide a more realistic calculation of the potential spoil <br />discharge. <br />With a pore volume of 416 ac.ft. and assuming a total recharge of 16" per year from all sources <br />over the 422 acres of spoil, annual recharge equals (16/12)(422) = 563 ac.ft. per year after full <br />irrigation in 2013. It should be noted that a portion of the reclaimed area will be restored to dry land <br />pasture and will therefore will not contribute irrigation recharge, however, other areas will have a <br />greater recharge than 16" total, therefore, the average of 16" over the reclaimed area is <br />reasonable. From the year 2003 to 2013, the expected recharge should only be 10% of this <br />amount, since irrigation will not be used on the majority of the area and the fresh - placed spoil will <br />be relatively dry. <br />Spoil spring discharge = (Spoil Spring Recharge) — (Seepage into tow Wall) <br />Seepage into Low Wall = (10 ft. thick permeable sandstone bed in lowwall)(8500 ft. wide seepage <br />area)(0.10 ft. per day seepage velocity)(1 /43,560 cu. ft. to ac. ft.)(365 days per year) = 72 ac.ft. <br />Spoil Spring Discharge = (563 ac.ft. recharge) —(72 ac.ft. seepage into lowwall) =490 ac.ft. In the <br />year 2000, the NPDES 001 discharge at the New Horizon #1 Mine showed an average flow of <br />271,000 gallons per day or 320 acre -feet per year. The NPDES 001 discharge is for practical <br />purposes composed entirely of spoil water. The New Horizon #2 irrigated spoil area is bigger, <br />therefore the predicted flow of 490 acre -feet per year for this area is a reasonable maximum flow <br />when compared to what is being observed at the #1 Mine. <br />Realistic case time to spring discharge = (Pore Volume) /(Recharge Volume) <br />= (416 ac.ft.) / (490 ac.ft.) = 0.8 years to actual spring flow after full irrigation is resumed on the <br />reclaimed land in 2013. This is the most realistic case of when the spoil spring will begin to flow. <br />In both the worst case and the more realistic discharge scenario, it may begin to discharge slightly <br />sooner since irrigation may begin on the eastern portion of the reclaimed area sooner than 2013, <br />thus contributing some discharge. Also, recharge from precipitation has not been factored in the <br />spoil prior to 2013. Assuming that the permanent pipe is installed in the year 2003 and has a life <br />of 30 years, the pipe would be replaced by the ditch in the year 2033. At this time recharge would <br />Revised August 2010 (PR06) 2.05.6(3) -24 <br />