ORD-2007-017 - Sedimentation and Erosion Control Ordinance

Browse Search

Or~n~e County SE & SC Ordinance ~°^'°^„~„~,.,'^~"~^^'Se tember 12. 20b6 3. Permissible Velocities The following is a table of permissible velocity for stormwater discharges: Maximum Permissible Velocities MATERIAI. FPS MPS Fine Sand (noncolloidal) 2.5 0.8 Sandy Loam (noncolloidal) 2.5 0.8 Silt Loam (noncolloidal) 3.0 0.9 Ordinary Firm Loam 3.5 1.1 Fine Gravel 5.0 1.5 Stiff Clay (very colloidal) 5.0 1.5 Graded, Loam to Cobbles 5.0 1.5 (noncolloidal) Graded, Silt to Cobbles (colloidal) 5.5 1.7 Alluvial Silts (noncolloidal) 3.5 1.1 Alluvial Silts (colloidal) 5.0 1.5 Coarse Gravel (noncolloidal) 6.0 1.8 Cobbles and Shingles 5.5 1.7 Shale and Hard Pans 6.0 1.8 Source: Adapted from recommendations by Special Committee on Lrigation Research, American Society of Civil Engineers, 1926, for channels with straight alignment. For sinuous channels, multiply allowable velocity by 0.95 for slightly sinuous, by 0.9 for moderately sinuous channels, and by 0.8 for highly sinuous channels. 4. Intent caused by increased velocity of runoff from the land disturbin ag ctivit~ SECTION 10 BORROW AND WASTE AREAS When the person conducting the land-disturbing activity is also the person conducting the borrow and waste disposal activity, areas from which borrow is obtained and which are not regulated by the provisions of the Mining Act of 1971, and waste areas for surplus materials other than landfills regulated by the Deparhnent's Division of Solid Waste Management shall be considered as part of the land-disturbing activity where the borrow material is being used or from which the waste material originated. When the person conducting the land-disturbing activity is not the person obtaining the borrow and/or disposing of the waste, these areas shall be considered a separate land-disturbing activity. 21