REP50830 - Laserfiche WebLink

Home Browse Search

r Memo to Joe Dudash Bowie #2 Mine -GOB Pile Density Study page 3 constructed. It appears, as earlier hypothesized, that a portion of the lowermost twenty feet of the GOB was not placed in complete compliance with the relative density standard specification. Does that represent a threat to the environment? Yes, it could. However, during each of my visits to the site during the past year, including our visit earlier this month, 1 have observed the toe and out slope of the GOB pile. I have not discerned any visible evidence of instability on the GOB pile. I am also no[ aware of any failures on the facia] out slope of the pile. For this reason, I do no[ consider [he GOB pile to represent an imminent threat. I cannot, however, discount the possibility that some problem may develop in the future. The brute force approach would be to require BRL to excavate and reconstruct the suspect portion of the pile. Because the portion in question is the outer half of the basal zone this would represent the excavation and reconstruction of the majority of the GOB volume. Since the pile is now being removed for washing by Powderhorn Coal Company, this possibility is not as improbable as it might normally be considered. A less extreme approach might include: (1) Reevaluation of the pile using appropriately adjusted material strength characteristics to reflect lower density, in order to determine whether the pile as-built will be stable; (2) redesign of the pile, if necessary, to consider partial excavation and reconstruction, andlor buttress addition; (3) submission and approval of an appropriate technical revision; (4) implementation of the necessary reconstruction or design modifications; and, (5) appropriate additional slope stability monitoring to verify success of the chosen remedial techniques. /' cc: Larry Routten ~ / y doc: M:\COALUAP\Bow2Gob3.WPD JP/jp