Laserfiche WebLink
could utilize the larger, more cnmpeteut. sandstone b.,ulder Fra~- <br />• meats in rock hutLress Lype walls. Such c•u ns t.rucl iuu could Lr <br />particularly effective if tLe alluvial gravel and cobble can Lr <br />utilized as backFit] and fill construction. Uraina~r, b„Ih <br />surface and subsurface will be extremely important in the east <br />portion of the waste pile and construction of the access zutd <br />permanent roads. Subsurface drainage of the coal mine waste bile <br />should be carefully addressed. If large amounts of water are <br />added as the waste pile is being constructed or if :urea wile <br />precipitation is allowed to soak or saturate the waste pile <br />during and after construction, a significant number c•f perched <br />water tables may develop. It has been the experience of Lincoln <br />DeVore, rlurinq the placement of exploration borings in existing <br />waste piles that, vertical permeability is very low relative to <br />• horiaontal permeability in the individual waste scrata or con- <br />struction lifts. In two instances, perched water tables were <br />encountered throughout the coal waste piles which uet•e under <br />construction, requiring a reassessment of the stahility of the <br />waste bank mass. <br />We hope this letter has provided you <br />with the information required. If questions arise or f~trtt,et• <br />information is needed, please feel free to contact Lincoln-De~ore <br />at any time. <br />Respectfully submitted, <br />LINCOLN-DeVORE, INC. <br />by: Edward M. Morris PE <br />Engineer/Western Slope Manager <br />LD Job x85688-J <br />• <br />8 <br />