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<br />MINING PLAN <br />I~tHIBIT D (eontl <br />The south ditch peak flow of 1 I.1 cfs will be handled by a ditch of the following design: <br />Bottom width: 1.0 feet <br />Channel slope: 4% <br />Sideslope 2.OHl.OV <br />Depth: 1.0 feet <br />Manning's n = 0.03 (earth channel with some vegetation) <br />Using the above inputs, Manning's equation calculates that the channel is capable of handling a <br />flow of 20 cfs at a velocity of 6.7 ft/sec. <br />Other Environmental Protection Measures Employed by the Operation <br />1) As discussed in the plans, the employment of the berm will cost more in the overal I operation to <br />construct and reclaim, but it is a very important item which will greatly reduce noise, dust and visual <br />impacts to all users of the Colorado River Road, Coffee Pot Road and the few occupied dwellings <br />south of the mining area. <br />2) The fact that the disturbed area will be limited to approximately 30 acres at a time is also very <br />important in reducing impacts to wildlife and visual resources from the higher reaches of Coffee <br />Pot Road. <br />3) In addition to the sediment pond and ditch system protecting increased siltation downstream, <br />groundwater will be protected by simply not mining any gravel that contains it. Due to the <br />extremely porous nature of the gravel deposit and by limiting the depth of the mining operation to <br />40 feet, groundwater is not expected to be encountered. Ifany subsurface water is encountered, the <br />Division and the Of2ice of the State Engineer will be notified to determine the best course of action. <br />95 <br />