2020-07-13_REVISION - C1981008 (2)

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E. Sedimentation Ponds 009 through 018 Design Parameters In accordance with Rule 4.05.2, Ponds 009 through 018 will be used to prevent, additional contributions of sediment to stream flow or runoff outside the permit area due to mining disturbance. The pond designs and or run-off calculations for the sedimentation ponds are shown below: Pond Attachment Maps Pond 009 Attachment 2.05.3(3)-5 Map 2.05.3(3)-5-1 Attachment 2.05.3(3)-30 Attachment 2.05.3(3)-30, Map 1 Pond 012 Attachment 2.05.3(3)-12 Map 2.05.3(3)-12-1 Attachment 2.05.3(3)-13 Map 2.05.3(3)-12-2 Attachment 2.05.3(3)-31 Map 2.05.3(3)-12-3 Map 2.05.3(3)-12-4 Attachment 2.05.3(3)-31, Map 1 Pond 013 Attachment 2.05.3(3)-32 Map 2.05.3(3)-32 Pond 015 Attachment 2.05.3(3)-22 Map 2.05.3(3)-15 Attachment 2.05.3(3)-24 Map 2.05.3(3)-19 Attachment 2.05.3(3)-33 Attachment 2.05.3(3)-33, Map 1 Pond 016 Attachment 2.05.3(3)-29 Attachment 2.05.3(3)-29, Map 1 Attachment 2.05.3(3)-29, Map 2 Attachment 2.05.3(3)-36 Map 2.05.3(3)-36 Pond 018 Attachment 2.05.3(3)-28 Attachment 2.05.3(3)-28, Map 1 Attachment 2.05.3(3)-28, Map 2 Attachment 2.05.3(3)-28, Map 3 Attachment 2.05.3(3)-35 Map 2.05.3(3)-35 Pond 013 will remain for some time after the reclamation of the surrounding land but will not be permanent. Map 2.05.3(3)-1 shows the locations of all ponds. The sedimentation ponds are designed, constructed and maintained as follows: a. Ponds 009, 012, and 013 have been designed to contain the 25-year, 24-hour event with no discharge from the emergency spillway. Ponds 015, 016, and 018 have been designed for a 100-year, 24-hour event with no discharge. b. The sedimentation ponds are designed to provide adequate sediment storage volume in compliance with the DRMS regulations. Actual designs are based on a minimum 3 year sediment volume based on USLE calculations. Actual construction may cut more volume below the dam level (incised storage)to lessen expensive cleanout during the operation. c. The principal spillway design is typically an 18-24" diameter CMP or other pipe which will have a valve on the entrance (see as-built for specific sizes). This pipe will be stopped down in the inlet side to a 6" valve which will be controlled by a wheel on the pond Section 2.05.3(3) Page 6 July 2020 (TR-99)