2023-02-03_REVISION - M1984094 - Laserfiche WebLink

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using a 12 feet wide bench will be used if any signs of instability are encountered.All of these items confirm that the planned mine slope is stable. MSHA requirements 1)30 CFR 56.3131 states that"In places where persons work or travel in performing their assigned tasks,loose or unconsolidated material shall be sloped to the angle of repose or stripped back for at least 10 feet from the top of the pit or the quarry wall. Other conditions at or near the perimeter of the pit or quarry wall which create a fall of material hazard to persons shall be corrected". By utilizing a pit excavation slope of].5H.-I V, which is 33.7 degrees, this is accomplished, since the loose material will have an approximate angle of repose of 40 degrees. Since the bank material has such cohesion, this angle has considerable safety factor. The angle of repose of the bank material is close to 90 degrees.Also, there should be no conditions at or near the perimeter of the excavated slope which would create a hazard. Workers will only be working in the track hoe and the trucks at the lowest bench level, which is 16 feet from the pit bottom. 2)A bench located immediately above the area where miners work or travel is to be maintained in a condition adequate for retaining material that may slide,ravel,or slough onto the bench from the wall, bank, or slope and that adequate escape routes be available in the event of a slope failure. If there is a potential for material to slide or ravel, (which is highyly unlikely),a safety bench of 10 feet width will be installed to catch material before the working bench is reached. I, Greg Lewicki, P.E., with over 30 years of experience in mine slope safety analysis in Colorado, state that this is true and that this factor of safety is adequate to prevent failure of any slopes in the mining and reclamation plan or to any off site lands. Gloria Z Mine 2013 Amendment 82