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The existing sediment catchment basin is adequate to control surface runoff and sediment yield. The small storage volume required and low peak discharge value adequately demonstrate that a sediment pond or other treatment facilities are not necessary for the topsoil stockpile area. Dorchester's initial request fora small area exemption for the topsoil stockpile area and access road, submitted on March 20, 1981, was approved by the CMLRD on April 14, 1981. Documentation of approvals for this small area exemption is included in Appendix B, CMLRD Letters of Approval for Small Area Exemptions. SUBSTATION N0. 2. POWERLINE. AND ACCESS ROAD On September 17, 1981 Dorchester requested a Small Area Exemption for Substation No. 2 and the powerline extending from Substation No. 2 to Substation No. 1. Powerline construction involved a negligible, one time, disturbance. The substation covers a 12 x 10 foot area. A 50 x 60 foot area surrounding the substation is graveled and fenced. The two (2) substations and connecting powerline are shown on the Drainage and Sediment Control Map, (Map 20). On March 17, 1982, Dorchester submitted a minor revision to the original small area exemption. The revision incorporated the extension of alight use road to Substation No. 2, as shown on the Drainage and Sediment Control Map, (Map 20), in the exemption area. The road extension encompasses a distance of 860 feet, located entirely on the old Rex Carbon Mine tipple and dump area. No drainages are effected, the road is located in a relatively flat area, and consistent with 4.03.3(4), no supplemental drainage control measures are necessary. Substation No. 2 is located on the nose of the NE trending ridge at an elevation of approximately 6,395 feet. The nearest surface drainage is 400 feet to the South-Southeast and average slope is 7 percent to the Northeast. The disturbed drainage area for Substation No. 2 is very small (0.7 acre) and is a graveled surface. A sediment fence will be placed at the east end of the substation pad to control runoff. The sediment fence is designed to safely pass the runoff from a 10-year, 24-hour storm event. Aii designs can be found in Appendix C, Hydraulic Documentation. There is no mixing of surface PEVTRI5.NEV 1111519311em 199R ~ Revised November 1993