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50 <br />the makeup of these materials is not indicative of components that would <br />potentially lead to acidic runoff or adversely affect groundwater quality. The <br />mine has a long history of stockpiling coal without encountering spontaneous <br />combustion. <br />The development waste, ditch cleanings, and pond cleanings will be permanently <br />stored in the new DWDA #2 located south of Highway 12 (DWDA 42). This <br />area was previously permitted as the clean coal stockpile area as shown on Map <br />11 Surface Facilities and Roads East Portal. As part of TR -66, the design <br />configuration for DWDA #2 will change. The storage capacity of the revised pile <br />will be about 125,000 BCY. Refer to Figure 13 for the plan and section view of <br />the proposed DWDA #2. The overall pile height will be 50 feet tall. Each 10 -foot <br />bench will be placed in up to 1 foot lifts and compacted with a track dozer. <br />Setbacks of 20 feet for each bench will result in an overall slope of 2.0(H):1(V) <br />during construction. A stability analysis for the TR -66 revised configuration can <br />be found in Exhibit 37(1). <br />Compaction testing was conducted by CTL/Thompson, Inc. for the New Elk <br />Development Waste Pile (DWP) at approximately 3 -month intervals in June, <br />September, and November of 1995 and March of 1996. The results are included <br />in Exhibit 31 as documentation supporting a permit revision "Compaction Test <br />Results New Elk Mine Development Waste Pile CTL/Thompson job No. 22905". <br />CTL/Thompson observed pile conditions and excavated four test pits. The <br />results indicated that the waste dump was stable if compacted to at least 90% of <br />standard Proctor maximum dry density (ASTM D 698). A CTL/Thompson <br />evaluation at that same time of alternatives for the disposal of pond cleanings and <br />ditch cleaning material indicated that the materials could be disposed of on the <br />development waste pile provided they are adequately drained and compacted. <br />DWDA #2 is at full capacity in the year 2012. NECC needs a temporary <br />development waste pile (temporary DWDA) as a transition to DWDA #3, which <br />will be constructed at the West Mine area. The temporary DWDA pile will be <br />located north and east of the stockpiles shown on Map 11, Sheet 3. Development <br />waste will be stockpiled for at least 30 days, and until such time that final <br />approval is received for Technical Revision No. 65 (DWDA #3). Material will be <br />placed in two -foot lifts and compacted as stated above in reference to DWDA #2. <br />The new Development Waste Disposal Area #3 (DWDA #3) is planned for the <br />area west of the west mine fan. The storage capacity of the west pile is about <br />155,000 CY. Refer to Map 12 for the plan and profile sections of the proposed <br />DWDA #3. The overall pile height will be a maximum of 90 feet. Material will <br />be placed in up to 2 ft. lifts and compacted to achieve at least 90% of standard <br />Proctor maximum dry density (ASTM D 698). The pile will have 314: IV side <br />slopes, and one 15' bench. The bench will slope back toward the pile at 2% and <br />to the runoff collection ditches at 2-5%. Design recommendations for the <br />Section 2.05 RN -6 10/17/2016 <br />