2016-02-24_REVISION - C1996084 - Laserfiche WebLink

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"Using watershed models, the operator must demonstrate that implementation of the Sediment Control Plan will result in average annual sediment yields that will not be greater than the sediment yield levels from pre -mined, undisturbed conditions The operator must use the same watershed model that was, or will be used, to acquire the SMCRA permit, The Operator must design, implement, and maintain BMM9 in the manner specified in the Sediment Control Plan. " From the discharge permit fact sheet: "Outfalls 005, 006, 007, 008, 030 and 031: The sole contribution to the ponds and their associated outfalls is stormwater runoff from reclaimed areas, all of which have been seeded. No spoils, springs or other non stormwater flows enter the ponds Discharges from the outfalls are intermittent and dependent upon storm events; The ponds discharge automatically when design capacity is reached, The ponds provide treatment by gravity separation (settling) prior to the discharge entering the receiving stream, " As discussed in the permit fact sheet, the ponds are currently in place, and function by gravity separation of suspended solids prior to discharge entering the receiving stream. The design of the sediment ponds is approved by DRMS, in the form of six sediment ponds, Ponds 005, 007a, 006a, 008, 009a (outfall 030), 009b (outfall 031). Design for the Sediment Ponds can be found in Exhibit 15. SedCad has been used to demonstrate that the sediment yield, during the reclaimed status of the Lorencito mine will be less than the pre -mining sediment yield with the sediment ponds in place. A comparison between pre -mining sediment loss and the sediment loss from sediment ponds has been prepared and incorporated into Exhibit 15-16. Per the terms of the discharge permit, a DRMS approved sediment control plan must be in place and submitted to CDPHE, no later than April 1, 2016. Please feel free to contact me if you have any questions. Regards, Ron Thompson Agent