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1 The embankment raise will be constructed with a crest width of 15 feet. This width will adequately accommodate a service vehicle, if necessary, as well as the tailings distribution pipeline and geomembrane ' anchor trench along the upstream edge of the crest and a safety berm along the downstream edge. Details of the embankment cross-section are sho~~m on Drawings 5461-C4 and 5461-C5. ' A shallow stormwater diversion ditch will be constructed adjacent to the northern perimeter of the impoundment to intercept overland runoff from the localized tributary area uphill of the facility and divert it safely around the impoundment to a natural drainage course to the east. The approximate location of the ' ditch is shown on Drawing 5461-C1 and details of the diversion ditch are discussed in Section 3.5 of this Design Report. ' 3.2.2 Construction ' In preparation for construction of the embankment raise, ponded water will be evacuated from the impoundment, to the extent practicable, in order to allow the surface of the existing tailings beach to dry and partially consolidate. The existing tailings distribution system along the embankment will be removed and salvaged, where practicable, for reuse in the expanded facility. it is expected that the basic design of the tailings distribution system will remain essentially unchanged, although the drop bars/spigots will have to be extended to accommodate the new embankment elevation and minor adjustments to drop bar locations may be warranted to optimize tailings distribution in the impoundment. The existing perimeter fence around the impoundment will also be removed and salvaged, where practicable. ' At the abutments for the raise portion of the embankment, foundation preparation will be conducted. Any vegetation, topsoil, loose rock or other deleterious material will be removed prior to placement of any ' new fill material. Where new fill is to be placed on the existing geomembrane liner (at the abutments, as well as along the crest of the existing embankment), a geotextile cushion layer will be installed over the existing liner to protect it from possible puncture by any sharp irregular rocks in the fill material. This ' cushion layer will consist of anon-woven, needle-punched geotextile, having a unit weight of 12 ozJsy. ' 1~Vithin the footprint of the embankment raise, the existing materials upon which the raise will be constructed (impounded tailings and the crest and downstream face of the existing embankment) will be prepared to provide a suitable foundation for the new fill. 'The downstream face of the existing embankment ' will be terraced, as necessary, to provide a series of stable, relatively level surfaces of sufficient width to allow efficient placement and compaction of new fill material. Where the embankment raise is to be constructed on top of existing impounded tailings, the surface of the tailings will be rough graded, to the extent practicable, to prepare a relatively uniform surface for placement of the initial lift of fill material. To provide a trafficable working surface in this area for earthmoving equipment, a biaxial geogrid will be installed on the regraded tailings surface, extending to the limits of the embankment footprint. The geogrid will provide flexible reinforcement for the initial lifts of fill, restricting the development of any slip planes and permitting controlled placement of the fill, while maintaining separation of the materials and allowing ' water to migrate out of the tailings as consolidation takes place under the superimposed load of the fill. Based on past experience, an initial lift thiclmess ofnvo to four feet_is typically sufficient to create a "bridge" over the underlying softer tailings and allow for com~entional placement of the remainder of the fill material ' The initial lift of fill will be dumped and pushed out onto the geogrid from the crest of the existing