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Jason Musick <br />C- 1996 -038 / TR -98 PAR - Geotechnical <br />11- Mar -2015 <br />Page 2 of 3 <br />2. During the Division's 2014 review of TR -89, the question was raised whether a stability analysis <br />for ditch side slopes / borrow areas was needed, where cut slopes of 1.5h:1v were proposed. <br />Rules 2.05.3(4)(a) and (d); 4.05.3(3) and (5); and 4.14.2(1), (1)(b) are pertinent to this situation. <br />While 1.5h:1v slope is roughly equivalent to 33 °, which is typical angle of repose for many <br />materials, the Division believes that a minimum static safety factor of 1.3 needs to be achieved <br />for the cut slope proposed for Borrow Area #3. Please evaluate the stability of the proposed <br />slope to ensure that the required FoS will be achieved. <br />Text - Volume IX (cover in application says Volume XI) <br />1. Please update the Table of Contents to show pagination changes resulting from TR -98. <br />2. The Certificate immediately following the TOC has not been updated since September 2013. <br />Please update to reflect the current status. <br />3. Page 4a of the approved PAP illustrates the changes to Gob Piles #2 and #4 that have been <br />approved under various revisions. Please update this diagram to reflect changes made <br />subsequent to TR -76. <br />4. Page 5 has been revised to include the East and North expansion proposed under TR -98. The <br />text indicates that no extension of the underdrain is necessary for East and North expansion. <br />According to Section A -A' (Figure 1), the pile is being extending further up valley. Please explain <br />why no extension is necessary. <br />5. On Page 6, in the first paragraph, the disturbed area for Gob Pile #2 -4 has been revised from <br />58.0 (approved) to 50.9 (proposed). Please provide an explanation for this decrease. <br />6. On Page 7, language in first 3 paragraphs has been written to speak of future activities ( "will <br />be ", etc.). Please update the text to reflect current status of these activities. <br />7. On Page 8, two paragraphs have been added to discuss Borrow areas #1, #2 and #3. The text <br />describes the volume of topsoil potentially available for salvage, but no estimate of the amount <br />of coverfill to be obtained from the borrow areas is given. Please revise the text to give the <br />volume of coverfill that is expected to be gained from these areas. <br />8. On Page 16 — Reclamation, the last sentence of the third paragraph appears to be missing some <br />text. Please revise, as appropriate. <br />9. On Page 18 — Stability Analysis, the first paragraph lists only Lambert & Associates and Buckhorn <br />Geotech. Please add Huddleston Berry Engineering & Testing to the list of geotechnical <br />consultants that have contributed to Volume IX. <br />Mar) - Volume IX Figure 1 <br />1. To the northeast of the coal mine waste disposal area, there exists a "hole" in the topographic <br />information presented. This gap in data is in a crucial location — the site of proposed Borrow <br />Area #3. Analysis of aerial photos suggests that there is a fairly massive sandstone outcrop <br />some distance above the proposed borrow area cut slope. Without topographic data, we are <br />unable to confirm that the sandstone will not be undermined by the proposed excavation. Any <br />undermining could contribute to toppling of sandstone blocks into the East Diversion Ditch. (An <br />event of that type appears to have occurred naturally, in 2007, from a point directly above the <br />proposed Borrow Area #3.) <br />