Laserfiche WebLink
boundaries will be staked prior to mining in the azea. This offset serves two purposes. First, the <br />volume of material left in the highwall will allow the crest to be pushed towards the toe with <br />final slope of 3H:1 V requiring no backfill material. Secondly, this offset provides additional <br />slope safety. It should be noted that the current highwalls with O.SH:1 V slopes demonstrate a <br />greater than 1 safety factor. It is demonstrated through no evidence of slope failure during the <br />life of the pit. However, a failure would be governed by the internal angle of friction of the <br />material. This would limit the failed slope to an angle of 38 degrees or ~1.3H:1 V. This failure <br />would not only stay within the permit azea, it would stay within the final slope envelope. <br />Three zones along the river bank have been determined to require erosion protection. These <br />locations can be seen on Maps C-2 and F, Some previous work has been done on the banks <br />using concrete slabs and rip-rap. This work will be augmented through the application of 4' d50 <br />boulders and/or precast erosion control concrete blocks. These blocks were designed for the <br />highly erosive Animus River. The block dimensions aze 4'x3'x3' and aze designed to be <br />interconnected with wire rope. These materials will be placed starting at the toe of the low water <br />level and cover a 14' slope length up the bank. The slope will be maintained at 2H:1 V or milder <br />in the erosion control areas. <br />Pit No. 1 1/04 2 <br />