Laserfiche WebLink
24 -hour event). The annual sediment yield was calculated with the Universal Soil Loss <br />Equation (Haan & Barfield, 1978) . The pond is designed to store two years of sediment <br />below the volume of the 10- year, 24 -hour event. Sediment from the pond will be <br />cleaned when 60 percent of the allocated volume has accumulated. A staff gauge, <br />located in the pond, will be used to monitor sediment accumulation. The 25 -year, 24- <br />hour capacity spillway will be located one foot above the design runoff and sediment <br />volume. <br />The primary spillway is a 4" cast iron pipe. Design features of Pond A are summarized <br />in the table below. As- constructed details of Pond A and associated facilities are shown <br />in Figure 4.3 -6. <br />Table 4.3 -6. Summary of Sediment Pond A <br />Actual Capacity 7.2 A -F <br />Required Capacity (Appendix 4.7 -2) 1.2 A -F <br />Stage Height to Contain 1.2 A -F 1.2 FT <br />During May or June 2012, an unapproved sediment collection ditch was constructed <br />south of Pond A. The ditch is shown on Figure 4.3 -6. The unapproved sediment <br />collection ditch was reclaimed during July 2012. Topsoil was placed on the reclaimed <br />ditch and the disturbed areas were seeded. The disturbance caused by the ditch <br />construction was about 0.02 acres (5' wide by 140 feet long). The ditch reclamation will <br />cause additional disturbance due to operating equipment along the ditch. This <br />additional disturbance is estimated to be 0.05 acres (15' wide by 140 feet long). <br />The Operator intends to have a third party drill two or three coal bed methane test wells <br />west of the Coal Ridge No. 1 Mine. These test wells will produce some water which will <br />be piped to the Coal Ridge No. 1 Mine sediment pond during 2007. The pipe will be laid <br />on the surface so no significant surface disturbance will occur. The water will be left in <br />the pond to evaporate. The field below the pond will be irrigated with the water if the <br />quality is suitable. At lease 1.2 feet of freeboard will be maintained to assure no <br />uncontrolled discharge occurs from the pond <br />The maximum <br />CB -Coal Ridge No. 1 4 -39 7/12 <br />