The required channel cross section and grade are determined by the design capacity based on Manning's Equation, the material of which the channel is to be constructed, and the requirements for maintenance. A minimum depth may be required to provide adequate outlets for subsurface drains, storm sewer pipes, tributary ditches or streams. The channel grade shall be such that the velocity in the channel is high enough to prevent siltation but low enough to prevent erosion. Channel lining materials must be justified by the project engineer in the final drainage design.
(Ord. passed 10-11-2004)