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Brock Bowles <br />Page 6 of 8 <br />December 12, 2014 <br />indicate that slopes are 33 %. The Division inspector directed WFC to verify the as -built slopes; it <br />does not appear that WFC has responded yet. Please survey the constructed Pond NHN -001 and <br />review the as -built certification of Pond NHN -001 to ensure that the pond has been constructed <br />as designed and that the as -built certification accurately reflects the constructed pond. <br />Rules 4.05.6(3): Section 2.05.3(4) and Appendix 2.05.3(4) -1 of the approved permit application <br />package include a discussion of the designs of the proposed sedimentation ponds. Each of the <br />three proposed sedimentation ponds has been designed to treat the runoff resulting from a 10 yr- <br />24 hr rainfall event, including the sediment expected to accumulate in one year's time. WFC has <br />committed, on page 4 of Section 2.05.3(4) to maintaining the pond to ensure that at least one year <br />of sediment storage is available beneath the primary discharge outlet. <br />Rules 4.05.6(4) and 4.05.9(2)(a) and (b): Each proposed sedimentation pond has been designed <br />with a non - clogging primary spillway and an open channel secondary spillway. <br />Rule 4.05.6(5): Calculations, documents and drawings, supporting the design of the proposed <br />sedimentation ponds are located in Appendix 2.05.3(4) -1 of the approved permit application <br />package. <br />Rule 4.05.6(6): The three proposed sedimentation ponds have been designed to prevent short - <br />circuiting. The design of Pond NHN -001 includes a tiered floor elevation to increase settling time <br />and prevent short - circuiting, and all three ponds were designed with gated primary spillways to <br />control settling time and prevent short - circuiting. <br />Rule 4.05.7: Each of the three proposed sedimentation ponds has been designed with a riprap <br />channel at the outfall of the spillways, as discussed on page 8 of Appendix 2.5.3(4) -1.. <br />Rule 4.05.9(1): Each of the three proposed sedimentation ponds has been designed in compliance <br />with Rule 4.05.9. <br />Rule 4.05.9(2)(c): The secondary spillway of each proposed sedimentation pond has been designed <br />for the 25 yr — 24 hr event. <br />Rule 4.05.9(2)(d): None of the proposed sedimentation ponds meet the Class B or Class C criteria <br />for dams established by the U.S. Department of Agriculture, Soil Conservation Service Technical <br />Release No. 60. <br />Rule 4.05.9(e): None of the three proposed sedimentation ponds will rely primarily on storage to <br />control the runoff from the 25 yr — 24 hr rainfall event. Each pond has been designed with a <br />passive open channel spillway to convey the 25 yr — 24 hr rainfall event. <br />