PERMFILE113777 - Laserfiche WebLink

Home Browse Search

Sent By: OXBG!"~ MINING INC.; 970 929 5177; Nov-20-UO S:G2PM; Paye 9i9 Catch bench recommendations Page 2 November B, :;OGO See attached figure from Ca11 )1986). Similarly, the wider a catch bench the more effective it will he and the longer it will function. The width of a catch bench is also controlled by the bench height and the maximum size nt the rock blocks which may be released over time. In this case the roughly 40foot thickness of the upper sandstone bed, rather ttlall the 15foot thickness of the lower sandstone bed, will control and require an approximately 22foot wide catch bench. The access road up to the catch bench can also Serve as mi~:or catch benches between the sw1Lc:Y~ backs. They should be sloped slightly inward toward the slope. The inward slope will also serve to channel water toward the sides and off the slope through the down drain riprap channels: The sensitive nature of the clays present in the slope mass necessitates removing rain and snow melt water from the slope as rapidly as possible. The riprap channels should be extended up to the catch bench. Culverts should be placed through the access road where the riprap channels intersect and intercept any water in the access road. It will probably be necessary to clean out the culverts when clearing debris frc+m the catch bench. The safety of the crew excavating the catch bench belo+.f the lower sandstone bed should be enhanced by scaling of the obviously loose blocks of rock at the crest of the two sandstone beds and sitting precariously on Lhe angle of repose shale slope between the two sandstone beds. Removing these loose rock blocks now will also extend the time interval between the periodic clearing of debris that will collect on the catch bench. Sincerely, John F. Abel, Jr. Colorado P.E. 5642 11-28-88 16:47 TO:MONTGOMERY WAT5ON FROM:97B 929 5177 P09