(A) Temporary structures may be used to control erosion and sedimentation on sites while under construction.
(B) While each site varies in size, shape and topography, the City Manager or his or her designee shall approve any one of the following types of temporary control depending on conditions specific to the site and on a case-by-case basis.
(1) Dikes. A diversion, interceptor or perimeter dike may be constructed on a site to control the stormwater run-off. The design drainage area for dikes shall not exceed five acres. Dikes shall not be constructed with a top width less than two feet or a height less than one foot six inches or side slopes steeper than a two to one ratio.
(2) Swales. An interceptor or perimeter swale may be allowed on a site where the design drainage area does not exceed five acres. Swales shall not be constructed with a bottom width less than four feet, a depth less than one foot, a grade less than 1% or slopes steeper than a two to one ratio.
(3) Straw bale dike. Straw bales shall not be allowed except in unusual circumstances when no other erosion control method would be effective.
(4) Silt fence. A silt fence may be constructed near the perimeter of a disturbed area to intercept sediment while allowing water to percolate through. The fence shall not encompass a drainage area more than two acres in size or be less than 30 inches in height. The fencing material shall be burlap, polypropylene fabric or nylon reinforced polyester netting or other equivalent materials designed for the same purpose. Steel fence posts spaced at a maximum of eight feet apart shall support the fence. Silt fences shall not be used where there is a concentration of water in a channel or other drainage.
(5) Entrances. A stabilized construction entrance shall be built to reduce or eliminate the tracking or flowing of sediment onto public streets and/or rights-of-way.
(6) Stone outlets. A stone outlet structure shall be constructed in areas where the entire drainage area to the structure is not stabilized or where there is a need to dispose run-off at a protected outlet or where concentrated flow for the duration of the period of construction needs to be diffused.
(7) Paved chute. A grade stabilization structure in the form of a paved chute or flume shall be constructed to prevent erosion, where concentrated flow of surface run-off is to be conveyed down a slope. The maximum allowable drainage area upstream of a structure shall not exceed 36 acres.
(8) Pipe slope drain. A grade stabilization structure in the form of a pipe slope drain shall be constructed to prevent erosion where concentrated flow of surface run-off is to be conveyed down a slope. The maximum allowable drainage area upstream of a structure shall not exceed five acres.
(9) Temporary sedimentation basins. Storm water detention facilities may be used temporarily as sediment basins.
(a) A temporary outlet structure for the storm water detention facility to work as a sediment pond shall be constructed.
(b) At the end of the construction activity, the developer shall make sure that the outlet structure shall meet the design requirements of a storm water detention facility.
(c) Condition of the detention facility that is used as a sediment pond during construction shall meet the following requirements at the time of acceptance.
(d) It shall be completely cleaned by the developer and rid of any immediate maintenance.
(e) It shall meet all design standards.
(10) Sediment trap. A sediment trap, a small temporary basin usually installed in a drainage way at a storm drain inlet, shall not exceed five acres and shall have at least 1,800 cubic feet per acre of drainage. Sediment trap embankments shall not exceed five feet in height, the top width shall not be less than three feet and the slopes shall have a ratio of two to one or flatter.
(C) Temporary structures shall remain in place until permanent vegetation is established.
(Ord. 3055, passed 12-21-99)