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Memo to Tony Waldron <br />Bowie IJo. 2 Geotechnical Adequacy <br />page 1 'I <br />BRL will have to propose specific reclaimed configurations. Cuts and <br />embanb:ments proposed to be retained as part of the reclaimed configuration <br />will have to be analyzed to demonstrate their structural and geomorphic <br />stability. The stability of backfilled facilities will also require analysis, at <br />least of typical situations. In potentially unstable sites, simply backfilling <br />cuts to original configuration may not result in a stable surface. Because of the <br />unique peak strength versus ultimate strength relationships commonly <br />characteristic of landslide-prone materials, once disturbed the placement and <br />recompaction of these materials may not recover their original pre-disturbance <br />strength. <br />Particular attention will also have to focused upon the drainage of reclaimed <br />areas and facilities, because of the deleterious effects of introduction of water <br />to landslide landforms. In the case of the Mount Gunnison No. 1 mine, stability <br />analyses determined that many of the retaining walls along roadways and portal <br />bench cuts need to be backfilled in place to attain stable final reclaimed slopes. <br />2.05.4(2)(f) Disposal of Debris, Acid-Forming and <br />Toxic-Forming Materials <br />As commented in relation to section 2.04.6 (Geology Description), an inadequate <br />discussion of the acid generating potential of the Upper B and Upper D coal <br />seams were presented in the text. Supporting chemical analyses are referenced <br />within Exhibit 6 of volume III. Page 2-04-18 of the application states; "It is <br />likely that time is present in adequate quantities to neutralize the acid forming <br />component in the coal." The limited geochemical analyses of the coal seams <br />provided within Exhibit 6 of Volume Ill show the Upper B-Seam to vary from <br />0.4% to 0.01 % (average 0.145%) dry weight pyritic sulfur. This data also shows <br />the Upper D-Seam to vary from 0.05% to 0.01% (average 0.027%) dry weight <br />pyritic sulfur. The data included within Exhibit 6 regarding occurrence of <br />calcium shows minimal amounts of soluble Calcium and Magnesium to be <br />present. in the roof and floor rock. No Calcium or Magnesium data is provided for <br />the two coal seams. No anion analyses, such as carbonate, or acid/base <br />potential determinations are provided for any of the coal., floor or roof <br />materials. BRL's conclusion that sufficient lime is present within the coal to <br />