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b) Filter Building <br /> See discussion below on Chemical Handling Systems and Containment. <br /> c) Thickener <br /> The thickener is 26 feet in diameter and 8 feet deep.The total height of the thickener from the ground is 15 <br /> feet.The volume of the thickener is a maximum of 4400 cubic feet of slurry.The concrete containment is bigger <br /> than the thickener itself and will handle a minimum of 110%of the full volume of the thickener.The thickener <br /> has a 6 inch thick reinforced concrete containment,as shown on Map 1. <br /> Based on the footprint area of 1693 sq.ft,as measured from the site inspection and using a minimum wall <br /> height of 3.0 feet, this results in a containment volume of 5079 cu.ft.Since there is approximately 200 cu.ft.of <br /> structures in the containment,the actual volume of containment is 5079—200=4879 cu.ft,which is 111%of <br /> the tank volume. The plans correspond to the designs presented in TR-05.The plan view of the foundation <br /> shown on Map 1. <br /> In the case of a rupture of the thickener tank or piping, a slurry pump is located at the low point of the thickener <br /> containment,which would then pump the slurry back to the 18000 gallon tailings tank located in the filter <br /> building. See Map 1. In this way, no tailings will be allowed to leave the area,although by the time that the <br /> tailings enter the thickener, they will be inert anyway.Therefore,with this system,there is actually triple <br /> containment of the tailings slurry at the thickener.These are 1)the tank itself, 2)the concrete secondary <br /> containment and 3)the sediment pond capture system. <br /> The slurry will be transported from the filter building to the thickener by overhead HDPE process water lines of <br /> 8"diameter.A return slurry line for concentrated slurry and a return waterline is installed on the bridge.The <br /> bridge will consist of a steel truss structure of 6 feet width and 100 feet long.An air line and electric cable is also <br /> suspended in the same bridge. The bridge is 18 feet high to allow clearance and all support structures are shown <br /> on Map TH-1 of the permit.As seen on this Map,there will be two support structures;one at the filter building <br /> end of the overhead truss and the other at the thickener end, and the distance between them is 100 feet.The <br /> truss supports at both ends will be steel supports in a foundation which is separate from both the thickener and <br /> the filter building,as shown on the revised TH drawings in the permit. <br /> Revenue Mill Certification Page 14 of 20 <br />