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<br />A diversion will be constructed above existing ~r7imPnt Pond 008 located <br />in the NFi; of Section 7, Township 5 North, Range 86 West. Tyre purpose of <br />this structise is to intercept surface water runoff so as to divert the <br />flow to Sediment Porri 008. 7.Yre runoff will then be treated by Pond 008 <br />prior to release thtrough Fond 008's NPDES discharge point. This system <br />will eliminate the need to oonstatlct a s >>++P*+tation porn near the center <br />of Sec,~tion 6. 4he following design disarsses the diversion ditch and the <br />redesign of Pond 008 spillways. Investigations show that Porri 008 can <br />harrlle the additional sediment load acrd surface water runoff with <br />modifications to the spillways. Peabody constnrcted a trapezoidal <br />emergency spillway tv comply with the c~rent Q~ffRD regulations. <br />SITE D~~T~ON <br />Sediment Fond 008 has a 340.9-acre W3tprchx3, The pond previously treated <br />• surface water from a 290.44-acre warp~~ that included a small diversion <br />ditch approved in TR 14. 'II1e diversion and pond system was approved in <br />TR-17. Zhe follaaing design was based on a worst case approach. It was <br />ac~mwA that sedimentation and surface rumff would be highest when the <br />disturbance was the hic~rest in the watershed. According to the current <br />mining plan, that situation will ooau~ in the beginning of 1993. <br />Diversion No. 1 (Deadhead 12otiIte) <br />A trapezoidal diversion ditch will be constructed on the east side of the <br />deadhead route at the toe of the fill. The ditch will be designed to <br />carry the flow as a result of the 10 year-24 hour precipitation event. <br />The exact location aryl slope of the diversion ditch will not be determined <br />until the deadhead route is wnstruc,-ted in 1993. The diversion will be <br />constructed as a trapezoidal channel in areas where the slope is less than <br />3.5 percent. When the slope is greater than 3.5 percent, the diversion <br />• ditch will be constructed as a trapezoidal channel if the material is <br />7-6f-1 Revised 08/24/92 <br />