Laserfiche WebLink
RESPONSE: <br />The design of Sedimentation Pond X002 has been revised in accordance <br />with CMLRB's regulation 4.05.6. In addition, Peabody Coal Company has <br />demonstrated adequate detention time in order to meet the requirements <br />of regulation 4.05.2. <br />2.05.3(4) Ponds, Impoundments and Diversions <br />Peabody Coal Company, via oral communication, has indicated to <br />the Division that the proposed 007 pond is to be relocated and <br />redesigned. Without a revision submittal to address this issue, <br />the Division must assume that the location and design submitted <br />with the permit renewal are accurate. Therefore, the comments <br />below have been included with this adequacy review. <br />If Peabody Coal does intend to revise the 007 pond location and <br />design, the Division strongly urges Peabody to submit a revision <br />addressing this issue by August 1, 1986. <br />RESPONSE: <br />Pond rf007's design has been revised and resubmitted to CLMRB on August <br />20, 1986 as a Technical Revision. <br />2.05.3(4) Ponds, Impoundments and Diversions <br />4. The proposed Pond 007 design calculations as submitted were <br />reviewed and the following information must be provided in order <br />to meet the requirements of 4.05.6(3): <br />a. How was the delivery ratio (DR) estimated at 32 percent? <br />b. Why was Manning's n assigned the value of 0.037? A <br />reference to channel bottom roughness type and corresponding <br />value should be provided for the emergency spillway design <br />calculations. <br />c. The pond has been designed to accommodate 1.0 ac-ft of pit <br />pumpage. However, the pond will fill to the outlet <br />elevation before dewatering occurs. Based on the <br />information submitted, this will provide insufficient <br />available storage for the design storm volume without flow <br />through the emergency spillway. The pond should be <br />redisigned with an outlet placed 1.0 ac-ft above the maximum <br />sediment storage level if storage of this volume of pit <br />pumpage is determined necessary. This orifice size should <br />be specified to demonstrate pond capacity exists for the <br />10-year, 24-hour storm volume. An outflow hydrograph based <br />• on this principal spillway should be provided to demonstrate <br />24-hour detention. <br />Revised 8/27/86 <br />