When the general layout of the site has been decided upon, a plan to control runoff from the site must be formulated.
(A) Divide the site into drainage areas. Determine how much and where the runoff will travel over the site. Consider how runoff can be controlled in each drainage area. Remember, in most cases it is easier to control runoff in smaller areas than to try to handle the entire site at some location downstream as it leaves the site.
(B) Select runoff control practices. Runoff control practices can be divided into three broad categories: vegetative controls, structural controls, and management measures. Local or state handbooks should be used to select and design appropriate vegetative and structural practices. Management measures are common-sense types of controls used to help minimize the need for physical practices.
(1) Vegetative control. Keep in mind that the first line of defense is to prevent increase in volume or rate of runoff. This is accomplished by protecting the soil surface as much as possible and not decreasing the overland flow time.
(2) Structural controls. Where large increases in runoff occur, structural practices are generally the only way to control runoff. It is very important that structural practices be selected, designed, and constructed according to standards and specifications of the engineer of jurisdiction. Improper use or inadequate installation can create problems which are greater than the structure was designed to solve.
(3) Management measures. Good site design and construction management is as important as any physical practices used for runoff control. The following are only some management considerations:
(a) Design site to help reduce runoff in open areas and not increase it;
(b) Use stage construction;
(c) Use as few pipe systems as possible; and
(d) Allow runoff to travel around within the site and not just straight through.
(Ord. 16-96, passed 4-15-1996)