2011-11-30_PERMIT FILE - C1981008A (5)

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Conclusion Pond 015 is designed to handle the drainage from 6.16 acres of land (worst case area) on the southern portion of the WFC /Johnson property at New Horizon Mine, which includes the area between Ditches C27 and D1 W,an area of disturbed ground associated with the advancing mining pit, and a small area of undisturbed ground on the west end of the property. This drainage area can be seen on Map 2.05.3(3) -20. A 100 yr -24hr rainfall even for Pond 015 will deliver a total flow volume of 0.508 ac -ft. The As -Built maximum storage volume is 0.94 ac -ft. Pond 015 has the capacity to hold a 100 -Year storm event plus three years of sediment (0.002 ac -ft). The construction of the pond was supervised and inspected numerous times by Ross L. Gubka, P.E. as WFC's company representative. Mr. Gubka as also surveyed the as -built pond accurately. He has a wide variety of experience in the design and construction of earth fill embankments and impoundments. Nothing was observed during the inspections that would indicate the pond has a potential for failure. The pond is a small dugout pond so there was no embankment to construct. There was no appearance of erosion, instability, structural weakness or other hazardous conditions. In the construction of the pond, sandstone rock had to be ripped from elevation 5559 up to 5570.5 to make volume. The sediment pond was constructed in accordance with the approved plan and applicable regulation in April 2011. The As -Built surveys of the sediment pond and associated ditch structures are shown on Map 2.05.3(3) -19 & 20 of the permit application package. Certification I, Gregory Lewicki, certify that the embankment of Pond 015 is stable, due to it's construction in native, competent sandstone. In my experience, embankments of this type have a Safety Factor in excess of five (5). '40—Onoll C,1®. 20335 Greg Lewicki Colorado Professional Engineer Registration No. 20335 (June 2011 TR -60) Attachment 2.05.3(3) -24 -3