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Modeling Results <br />The results of the SEDCAD modeling are provided in Appendix F. Modeling demonstrates that the <br />existing sediment pond is adequate to control and treat runoff from the RPE and the RPE East for the <br />10 -year, 24 -hour storm as described in Section 3.2. <br />3.2 Ponds, Impoundments, Other Treatment Facilities and <br />Diversions (Rule 2.05.3(4) & 4.05.6) <br />The sedimentation basin serving the existing RPE provides adequate capacity to store the runoff from <br />the 10 -year, 24 -hour storm event for the RPE and RPE East areas. Sediment and clear water <br />diversion ditches have been designed to provide capacity for runoff from the 100 -year, 24 -hour storm <br />to meet requirements of the Rules. Additional information regarding these facilities is provided in <br />the following sections. <br />3.2.1 Design Inputs and Assumptions <br />The three main design components for surface water runoff control for the RPE East include: <br />• Sediment ditches to capture surface runoff from the RPE East refuse pile <br />0 • Clear water diversion ditches to capture and divert surface runoff from area above the fill <br />• Sedimentation pond to capture and treat runoff from the sediment ditches <br />Sediment Ditches <br />In accordance with Rule 4.09.3 and 4.09.2(7), the sediment ditches have been designed to safely pass <br />runoff from the 100 -year, 24 -hour storm event. <br />Clear Water Diversion Ditches <br />In accordance with Rule 4.09.2(7), the clear water diversion ditches have been designed to safely <br />pass the runoff from a 100 -year, 24 -hour storm event. <br />Sedimentation Pond <br />The existing two - celled RPE sedimentation pond located northwest of the proposed RPE East will be <br />used to treat runoff from the RPE East and its sediment ditches. Per the Rules, the sedimentation <br />pond contains and treats runoff from the 10 -year, 24 -hour storm event and has an adequate sediment <br />storage volume with periodic sediment removal to effect compliance with water quality regulations <br />• �S `� <br />Revised April 19, 2010 � ���L- <br />L <br />Z3 <br />P:Vv4pls \06 CO \26 \06261003 MCC Refuse Pile Site Review & Permit \WorkFiles\Permit Application \Text\2010- 04- 19_RPE East Permit Application.doc12 <br />