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• wide gravel berm section with filter fabric. This section will be installed in the lowest 30' section of <br />the exemption area and will serve to filter sediment out before gradually releasing the water through <br />the gravel embankment. A schematic of this installation is shown on the following page as Figure <br />2.05.3(3)-7-1. The filterfabricto be used is Mirafi Filterweave UV fabric. The enclosed specification <br />sheets show that this fabric has strong UV resistance and is also well-suited to filtering sediment <br />from flows in this situation. It also allows thewater to pass without any detention. The specificfabric <br />FW403 is designated for use, which has a 6% open area and a flow rate of 2852 gallons per <br />minute per square foot. The gravel embankment will consist of minus 3"durable rock. A portion of <br />the filter will be buried below the embankment as shown and a height of 2.0 feet above the filter <br />will be used to handle very large events. The filter will also be slightly buried at key locations to <br />keep it in place on the upper portions of the embankment. <br />Accordingly, Map 2.05.3(3)-1 shows the locations of four SAE's, numbered #1 (existing) and #3, <br />#4 and #5 (planned) plus the location of Pond 014 which was formerly SAE #2. SAE #6 which <br />moves in advance of the pit, is constantly changing location and cannot be shown. A further <br />• discussion of Pond 014 can be found in Section 2.05.3(3) Mine Facilities. Storm volume <br />calculations for this pond are given in Attachment 2.05.3(3}11. This pond restored an original <br />depression in the landscape at the same location. It drains an area of only 1.3 acres. <br />SAE #6 replaces the previously approved traveling pond design. SAE #6 is designed to detain all <br />runoff from the narrow strip of land in advance of the pitwhere topsoil stripping is taking place. This <br />width is approximately 100 feet and runs the entire width of the cut from north to south. WFC <br />commits to placing a portion of the topsoil that is being stripped in a continuous berm at the <br />western edge of the pit disturbance for sediment control of this area. The berm will be a minimum <br />of 4 feet high with sideslopes of 2H:1 V. See Map 2.05.3-1 which shows the berm in relation to the <br />entire pit cross section. <br /> <br />REVISED MARCH 2006 Attachment 2.05.3(3)-7-4 <br />