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. drains will consist of a toe drain and bench drains as show on Figure 4 of <br />Lambert's report. Bench drains will be constructed on 50-foot vertical centers or <br />at any damp spots encountered in the coal mine waste disposal area founding. <br />See Figure 2 for the layout of the lateral drains. <br />The lateral drains will not be in hydraulic communication with the rock under- <br />drains, since they might inadvertently permit the infiltration [Rule 4.09.1(13)) of <br />water. See the detail on Figure 1 which shows how the lateral drains will be <br />isolated from the rock under-drains. <br />The run-off and collection ditches are shown on Figure 2. Run-off from the <br />benches will be directed to the east and west to collection ditches. The east and <br />west collection ditches D-F6 and D-F22 are; 1) lined with riprap to ensure they <br />are stable; 2) constructed off the fill and; 3) designed to safely pass the run-off <br />from the 100-year, 24-hour precipitation event. Ditches D-F6 and D-F22 are also <br />designed to safely pass the run-off from the 100-year, 24-hour precipitation event <br />from the upper diversion ditches. <br />. The upper diversion ditches and the east and west collection ditches will be <br />constructed prior to placement of coal mine waste. During construction of the <br />pile, a bench configuration will be maintained at fhe contact point between the <br />coal mine waste and the natural ground surface. Thus, run-off from above the <br />pile and below the upper diversion ditches will be directed to the east and west <br />collection ditches by the temporary benches. The temporary benches will be <br />configured the same as the permanent benches. <br />See Appendix B for detailed design information of the run-off and collection <br />ditches. <br />LJ <br />TR-30 - 6 - 02/04 <br />