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-31- <br />Eastside's proposed mining operation during the first permit term will be <br />limited to the E seam, accessed through the existing portals. Coal will be <br />mined across the pitch of the 20 foot thick coal seam, which dips at 59o to <br />the south. Extraction will be by a modified room and pillar method, with a <br />maximum production of 250,000 tons per year during the first permit term. <br />The proposed operation is in compliance with the requirements of this section. <br />XVI. Backfilling and Grading -- Rules 2.05.3(6), 2.05.3(9) and 2.04.4(2 <br />O l1C A O .. A AA A 7 ...A A lA <br />The application depicts a series of backfilled cross sections and postmining <br />contours on pages 103 through 117, which represent approximate original <br />contour in the reclaimed portal and facilities areas. Material balance <br />calculations on page 101 of the application demonstrate that the proposed <br />configuration can be achieved with material available on site. <br />In the adequacy letter of July 25, 1984, the Division requested that the <br />applicant demonstrate that the slope stability requirements of Rule <br />4.14.12(1)(b) would be achieved in the case of the steepest "worst case" <br />slopes in the reclaimed portal vicinity as depicted on cross section <br />drawing 28. The applicant has presented a simplistic comparison of the angle <br />of repose and the tangent of the final slope to suggest that the static slope <br />safety factor exceeds the required standard of 1.3. This simplistic approach <br />assumes ideally granular materials which the local spoil and bedrock materials <br />are not. <br />The following stipulation is necessary: <br />STIPULATION N0. 8 <br />WITHIN 3 MONTHS OF PERMIT ISSUANCE, THE PERt4ITTEE WILL PREPARE AND <br />SUBMIT TO THE DIVISION FOR APPROVAL AN APPROPRIATE ANALYTICAL <br />DEMONSTRATION OF THE PROPOSED TOPOGRAPHY'S SLOPE STABILITY. "WORST <br />CASE" SITUATIONS FROM CROSS SECTIONS IN THE APPLICATION WOULD BE <br />ACCEPTABLE. THE REPORT PREPARED BY LAMBERT & ASSOCIATES INCLUDED IN <br />THE APPLICATION SHOULD PROVIDE THE NECESSARY MATERIAL STRENGTH <br />PARAMETERS. <br />The application contains plans for a 30,800 yd3 underground development <br />waste pile to be constructed at the head of a small valley on the west side of <br />County Road 237, directly to the west of the surface facilities at the mine. <br />The pile will be constructed in 2 foot compacted lifts to a maximum height of <br />50 feet with a 2:1 (horizontal vertical) outslope. As the pile increases-in <br />height (with subsequent lifts progressing up the valley) soil will be stripped <br />ahead of the pile and 2 feet of soil cover will be replaced on the 2:1 slope <br />and revegetated. <br />