2017-04-12_REVISION - M1977193 - Laserfiche WebLink

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prior to mine bench development. These soils contain higher amounts of clay and fines that will better retain moisture and support vegetative establishment. Prior to planting medium application, simple half"v" ditches will be located along side access trails installed at forty-foot elevation intervals. The ditch will be located along the cut bank side of the minimum 10' wide trail. Access trails will be constructed to drain to ditch at cut bank at 10% gradient into slope. All surface ditches will grade 1%northward and converge along the northwest aspect of the stockpile at its intersection with bedrock outcrop. A rock lined channel will collect and direct all ditch flows northeast to the existing stormwater flow route across the pit floor and northwards into the stormwater control/sediment control ponds located near the center of the Phase 1 area shown on the revised Exhibit C Mine Plan Map. Planting Medium Application and Re-vegetation Once the structure's final height, gradient, and ditch works have been attained, a layer of planting medium will be placed on the surface to a minimum depth of 12". The planting medium is comprised of shallow fine grained soils, organic materials and surface fines containing clay, sand, and weathered granite gneiss with small amounts of weathering derived clay minerals. Much of the granite gneiss contains moderate amounts of fine grained biotite, a flaky, relatively soft aluminum silicate mineral similar to muscovite, a common component of many granite and granite gneiss rocks. These minerals have a tendency to hold moisture and promote root development and vegetative establishment. The material will be un-screened, meaning that larger (up to 20") rocks may be present. These rocks will act as mulch and as micro-site locations offering shade, moisture retention and wind block for emerging grass and shrub seedlings. Once the planting medium is in place and final graded, contour furrows will be installed using a triple ripper assembly applied with staggered overlap to achieve a series of rough, up to one foot deep furrows along the horizontal contour from top to bottom of the storage structure. Broadcast seeding of the approved seed mixture (attached) will be performed prior to covering the area with clean straw mulch at a rate of 20009 per acre. Seeding and mulching applications will be performed during late winter or early spring time of year. Grass establishment will be evaluated each year and additional seeding and mulch distribution will continue if needed to establish a diverse and sustainable vegetative mode. Storm ditches will be accessible via access trails wide enough for a pick up and small excavator(10') for maintenance of ditches and seed/mulch application.