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to the top of the sediment will be gradually released to and through the channels and <br />will flow to the most downgradient EMP structure, EMP -17. The SEDCAD <br />computations show that six 1 -inch perforations per row on 12 -inch vertical centers <br />will result in the non - terminal ponds draining in about two days. EMP -17 is a former <br />pond associated with the historic Cameron Mine, which will be reconstructed to a <br />19.7 acre -foot size that will allow the EMP pond store excess storm water runoff <br />from other upstream EMPs. Two ponds upgradient of EMP -17 will first receive the <br />storm water runoff from upstream channels and have been sized to settle all but fine <br />silt and clay. The outlets from the upgradient ponds will be 12 -inch pipe, selected <br />such that the outflow is to the main EMP -17 pond will yield an area/flow ratio of 500 <br />square feet/cfs. By that design, the sedimentation that accumulates in the two <br />upgradient ponds can be removed on a routine schedule while the accumulations of <br />sediments in the EMP -17 will be minor and may not require removal of sediments. <br />b. The receiving channel from all non - terminal structures in Grassy Valley (fitted with <br />perforated outlets as described above) will be augmented with growth media placed <br />within the riprap spillway and seeded to provide a vegetative filter. The vegetative <br />filter will remove colloidal clay and fine silt from the storm water runoff that pass <br />through the perforated outlets and onto EMP -17. <br />c. Finally, the storm water runoff that accumulated in EMP -17 could either be released <br />to Grassy Valley in accordance with the Storm Water General Permit, or can be <br />withdrawn and used for dust - control and construction water at hte Cresson Project. <br />10.4 AGVLF and SGVLF Diversion and Sediment Control <br />Storm water runoff will also be routed around the VLFs. Temporary diversion channels may be <br />constructed as necessary to route upgradient storm water runoff around SGVLF during the <br />construction phases. These temporary diversion channels are discussed in Appendix 9, Volume <br />V of this document for the SGVLF and in Appendix 8, Volume V of the MLE application for the <br />AGVLF. <br />Sediment control during SGVLF construction activities will be the responsibility of the <br />contractors following guidelines established by CC &V. Contractors will be required to install <br />and maintain appropriate storm water runoff and erosion controls structures during construction <br />of the facilities. Best Management Practices (BMPS) for sediment control may include riprap <br />channels, rock check dams, hay bales, silt fence, erosion control fabric, and other effective BMPs <br />as appropriate. <br />Cripple Creek & Victor Gold Mining Company <br />Cresson Project Mine Life Extension 2 <br />10 -5 <br />