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<br />• <br /> <br />MSt3Eation Detail Comments: <br />1) The beam and catchment is located and designed to minimize the impact forces and bounce height <br />at the fac:c of the berm. The height of the berm was chosen so that rocks would likely strike on the <br />bottom Ei0% of the berm total height. In addition, the berm is designed for an impact energy (design <br />capacity] of approximately one million ft-ibs with limited dcIIection of the back face. Additional <br />deflection is acceptable but may require repair. The ultimate capacity of the berm is likely to be <br />considerably higher than the design capacity. <br />2) We have added notes to limit the height of the temporary 1:1 cuts to 8 feet. BRL has stated that <br />they inttaid to construct all of the final slopes at 1.5:1. Overall, these berms are temporary with an <br />expected service life of 3 months. Global slope stability calculations show global factors of safety <br />exceedvag 1.3 for the designed ditch and berm geometry. These calculations aze attached. <br />3) Drainage will be field fit based on the slope conditions at the location of each berm. In general, <br />there should be a minimum of 5% grade slope to the end of the berm to prevent water from ponding <br />in the ditch. Additionally, 7.E. Stover & Associates is designing drainage to control the surface water <br />in the form of PVC pipe along the ditch with appropriate outlets on the slope below. if necessary, the <br />outlets •will be treated to prevent erosion in front of the berms. <br />4) These are temporary berms that <br />subsidence event, Also, the final s <br />5) Notes have been added for <br />~ ARer the subsidence event, the be <br />necessary. The current design does r <br />temporary. If the bemts aze made pe <br />is expected to continue operation for <br />~ Beans should be overlapped a <br />was a draffing error. <br />Please call if you have any questions. <br />Sincerely, <br />YEH AND ASSOCIATES, INC. <br />/ " ~. <br />Mall n n, P.E. <br />Attacbments: Globa[ stability calculations <br />be made permanent upon further evaluation following the <br />will all be at 1.5:1 rather than 1:1. <br />and foundation preparation. <br />shall be inspected, repaired, and made permanent if <br />include UV protection for the geofabric because it is <br />anent, then this issue will be addressed at that time. The mine <br />out 15 years. <br />of 20 feet, as determined in the field, Tlie lack of overlap <br />/n P_- ~ y <br />floPRovEI~ 3~~q~0y <br />