Laserfiche WebLink
<br /> <br />Memo to Joe Dudash <br />Bowie No. 1 Mine -East Ridge Waste Pile <br />page 2 <br />J. E. Stover and Associates, consultant to BRL, states; "Since the slopes and waste <br />pile configuration of the East Ridge Pile are the same as the West Ridge Pile, and <br />the waste material properties have not changed, no further stability analyses are <br />considered necessary." Because the overall loads applied by the increased vertical <br />extent and mass of the extended waste pile appear to be considerably higher per <br />unit of foundational area, I do not concur with this statement. In accordance with <br />Rule 4.10.4(2), the detailed design for the East Ridge Waste Pile extension must <br />include a specific stability analysis which demonstrates that this coal mine waste <br />bank will have a minimum static safety factor of 1 .5. I do concur with J. E. Stover <br />& Associates opinion that the previously determined material strength parameters <br />can be used in completing the required stability analysis. <br />BRL also proposes to construct an underdrain within the existing drainage low <br />beneath the foot print of the East Ridge Waste Pile, which is consistent with the <br />original conceptual design for the "49 Year Pile" extension. J. E. Stover & <br />Associates states that the underdrain specifications detailed in the 1 994 <br />modification to the waste pile design (in permit Volume 8) will be adhered with by <br />BRL when constructing the underdrain. These specifications continue to be <br />acceptable to the Division. Finally, BRL has completed drainage calculations which <br />determined that an additional sediment control pond should be constructed in <br />connection with the East Ridge Waste Pile, and an appropriate design and sizing <br />calculation is provided. <br />cc: Larry Routten <br />doc: M:\COAL\JAP\BOW1TR29.WPD <br />JP/Jp <br />