6.4. SR 08-20-2007 - Laserfiche WebLink

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I I I I I I I I I I I I I I I I I I I 9.) . - I leave the site at an eleviation ranging from 1050-1070 feet above msl. The tops o~ the sides lopes along the eastern and southern portions of the property will match the existing grade at the perimeter of the mining limits which are at approximately 1 080-1 090 feet above msl. Figure 3 is a U.S.G.S. Quad map excerpt that illustrates the site setting. c. Estimate of Quantity of Material to be Mined: The estimated net quantity of material to be removed from the property is between 300,000 and 400,000 cubic yards. This does not include topsoil or overburden. d. Depth of Water Table: The depth of the water table was identified during the Elk River Gravel Mining District EIS process. The water table ranges from about 930 feet above msl in the northwest corner of the site to about 925 feet above msl in the southeast corner of the site. Groundwater flow direction is to the southeast. The elevation of the water table corresponds to approximately 160 feet below existing grades, 60 feet below excavation grades and 120 feet below reclamation grades. e. Average thickness of overburden The average thickness of overburden is estimated to be 20 feet. Plan of Operation: The plan of operation is to strip the overburden, utilizing some of the material to create a perimeter screening berm along the eastern portion of the proposed mining area. After the overburden has been stripped, material will be excavated starting from the floor of Tiller's existing operation moving from the north to towards the south and lor from the west to the east. This will keep all mining and processing equipment recessed 70-100 feet below the surrounding grade. This will minimize visibility as well as noise and dust emissions. Crushing and screening will take place throughout the mining operation. Processing equipment will generally move along with the progression of the active face. Conveyors will be used throughout the Page 5 of 10