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~,. !s <br />_5_ OL, ,.~~• <br />2. Paragraph 3 of this section states that "No alteration or relocation <br />of a natural drainageway is expected". This is not consistent with <br />the operator's apparent plan to mine the channel. All such references <br />within the application must be rectified. (Refer also to <br />Sections 2.05.6.3.2a and 2.05.6.3.2e). <br />2.05.3(4) - Ponds, Impoundments and Diversions <br />Diversion Ditches <br />1. The submitted drainage control plan is not adequate. The applicant must <br />provide specific ditch designs for all site ditches including upland <br />diversion ditches and containment ditches (Rule 2.05.3(4)). This can <br />' only be done after the operator provides a specific mine plan which <br />cc's'"'~ indicates the anticipated number of mine phases. The designs must <br />~« indicate design peak flow estimates, flow velocity estimates, ditch <br />labels, ditch locations, riprap criteria for areas with erosive flow <br />velocities, and ditch dimensions. <br />2. The application Section 2.05.3(4) indicates that all ditches will be <br />sized to convey the 100 year, 24 hour peak flow (Rule 4.05.3 only <br />requires sizing for the 2 year, 24 hour peak flow). The design discharge <br />is given as 5.62 cubic feet per second (c.f.s.), a figure which does not <br />~ % agree with any provided in the SEDCAD output contained in Exhibits 5 <br />through 8. <br />The 2 year, 24 hour peak flows derived for Phase 1 and Phase 2 are <br />13.4 c.f.s. and 8.1 c.f.s., respectively. These values are for the <br />actual mine phase areas and they do not include the flat areas below the <br />phase areas which must also be accomodated. The 100 year, 24 hour peak <br />flows for Phase 1 and 2 are 34.6 c.f.s., and 20.9 c.f.s., respectively. <br />3. Culvert sizing must also be included with the revised drainage control <br />~C / plan, as well as provisions to protect any culverts which cross the <br />Engleville Gulch, from flood flows. <br />4. The applicant must plan for a containment ditch to be located at the <br />,~ ~ northwest section of the permit area. <br />Pond <br />1. The pond must be designed to store and/or treat the 10 year, 24 hour <br />storm volume from the disturbed area. The primary dewatering device <br />must be located above the maximum sediment storage elevation, and it is <br />recommended that the stored water should be dewatered within 10 days of <br />the storm. Additionally, the flow must be retained fora time period to <br />ensure that total suspended solids and settleable solids effluent <br />standards are met. <br />Numerous problems have been identified with regard to the submitted pond <br />design: <br />