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Orange County SE & SC Ordinance October 23 2007 <br />3. Permissible Velocities <br />The following is a table of permissible velocity for stormwater discharges: <br />Maximum Permissible Velocities <br />MATERIAL <br />FPS <br />MPS <br />Fine Sand (noncolloidal) <br />2.5 <br />0.8 <br />Sandy Loam ( noncolloidal) <br />2.5 <br />0.8 <br />Silt Loam (noncolloidal) <br />3.0 <br />0.9 <br />Ordinary Firm Loam <br />3.5 <br />1.1 <br />Fine Gravel <br />5.0 <br />1.5 <br />Stiff Clay (very colloidal) <br />5.0 <br />1.5 <br />Graded, Loam to Cobbles <br />5.0 <br />1.5 <br />(noncolloidal) <br />Graded, Silt to Cobbles (colloidal) <br />5.5 <br />1.7 <br />Alluvial Silts (noncolloidal) <br />3.5 <br />1.1 <br />Alluvial Silts (colloidal) <br />5.0 <br />1.5 <br />Coarse Gravel (noncolloidal) <br />6.0 <br />1.8 <br />Cobbles and Shingles <br />5.5 <br />1.7 <br />Shale and Hard Pans <br />6.0 <br />1.8 <br />Source: Adapted from recommendations by Special Committee on Irrigation Research, American Society of <br />Civil Engineers, 1926, for channels with straight alignment. For sinuous channels, multiply allowable velocity <br />by 0.95 for slightly sinuous, by 0.9 for moderately sinuous channels, and by 0.8 for highly sinuous channels. <br />4. Intent <br />Stream banks and channels downstream from any land disturbing activity shall be <br />protected from increased degradation by accelerated erosion caused by increased <br />velocity of runoff from the land disturbing activity. <br />SECTION 10 BORROW AND WASTE AREAS <br />When the person conducting the land- disturbing activity is also the person conducting the <br />borrow and waste disposal activity, areas from which borrow is obtained and which are <br />not regulated by the provisions of the Mining Act of 1971, and waste areas for surplus <br />materials other than landfills regulated by the Department's Division of Solid Waste <br />Management shall be considered as part of the land - disturbing activity where the borrow <br />material is being used or from which the waste material originated. When the person <br />conducting the land - disturbing activity is not the person obtaining the borrow and/or <br />disposing of the waste, these areas shall be considered a separate land - disturbing activity. <br />21 <br />