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from leaving. The liner will be sloped to a sump and a pump <br />• provided to remove water as it accumulates. Any water pumped from <br />within the liner system will be sprayed onto the coal pile as a <br />dust suppressant. <br />Other miscellaneous facilities which will be added to the site <br />include a portable chemical toilet, office trailer, latex sprayer, <br />and dust-suppressing water sprayer. <br />9.2.9 Ponds and Diversions <br />4.2.9.1 Ponds <br />One surface runoff pond will be constructed to control sediment and <br />surface water draining from the permit area. The sediment pond <br />will be located in the southwest corner of the permit area which is <br />the lowest portion of the (3.60 acre) lease property (Figure 9.2- <br />• 4). Two additional portions (0.75 acres) of the total lease of <br />4.35 acres which will not drain into the sediment pond will require <br />low berms to retain runoff and sediment (Figure 9.2-4) Calculated <br />runoff values from the 3.60 acre tract and the smaller areas (0.75 <br />acres) are provided in Appendix 9.2-1. <br />The sediment pond is sized in accordance with applicable CMLRD <br />regulations, and the Soil Conservation Service (SCS) procedure for <br />determining peak flows in Colorado was used to calculate the pond <br />volume (10-year, 24-hour event) and the pond spillway capacity (25- <br />year, 24-hour event (although the spillway will safely pass the 100 <br />year event) (Appendix 4.2-1) The annual sediment yield was calcu- <br />lated with the Universal Soil Loss Equation (Clyde and others, <br />1979). The pond is designed to store three years of sediment below <br />the volume of the 10-year, 24-hour event, assuming a highly <br />erodible surface. Sediment from the pond will be cleaned when 60 <br />percent of the allocated volume has accumulated. A staff gauge, <br />• NCIG - Load Out Revision 4-6 ASC/1145/910531 <br />L/5~91 <br />