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i.0 DE82GN CRITERIA <br />The evaluation makes the following assumptions with respect to <br />design criteria: <br />1. The existing pads are considered to be of acceptable stability <br />and design based on the regulations under which they were <br />constructed {the 11/30/83 version). <br />2. The pad expansion will be designed using the regulations fort <br />coal waste banks (Section 2.05.3(8):Coal Nine Waste and Non- <br />Coal Processing Waste, and Section 4.10: Coal Nine Waste <br />Banks). This assumption follows from the fact that the pad <br />expansions will be constructed from material from the <br />development of the access tunnels. In these regulations, <br />"underground development waste" is defined as "coal mine <br />waste" [Section 1.04(22a)]. The design will conform to: <br />• appropriate subdrainage <br />• slope protection against erosion <br />• minimum static safety factor of 1.5 <br />• approved lift thicknesses and compaction <br />• slope no greater than 2h:ly (50$) <br />• covered with an approved 16" layer of topsoil <br />3. The design of the slopes of the pad expansions will conform to <br />the requirements for permanent reclamation of these slopes, as <br />set forth in Section 4.14.2: <br />• slopes will approximate pre-mining slopes <br />• minimum static factor of safety is 1.3 <br />• slope terraces of less than 20 feet width are allowed <br />• terrace outslopes shall not be steeper than 2h:ly (50 e) <br />These slopes will be revegetated immediately after placement, <br />which will allow the option of either leaving them in place at <br />the end of the project, or excavation and placement bac'r, in <br />the tunnels, whichever is considered mcre aesthetically <br />pleasing. <br />•-~~ Zfsa.~~ Brown Consultants -2- <br />:145/900:31 <br />