(a) Sediment control practices and construction details of these practices must be provided for all structural practices that shall store runoff, allowing sediments to settle and/or divert flows away from exposed soils or otherwise limit runoff from exposed areas.
(b) Structural practices shall be used to control erosion and trap sediment from a site remaining disturbed for more than 14 days. Such practices may include, among others: sediment settling ponds and earth diversion dikes or channels which direct runoff to a sediment steeling pond. All sediment control practices must be capable of ponding runoff in order to be considered functional. Where five acres or more, of development area are disturbed in one watershed, storm water runoff from that watershed shall pass through a sediment basin or other suitable sediment trapping facility with equivalent or greater storage capacity. All sediment basins and/or traps must provide a minimum storage of 67 cubic yards per acre of total contributing drainage area. The use of a dewatering device must be provided on the outlet structure to allow dewatering of the facility and ensure adequate time for sediment settlement. When determining the total contributing drainage area, off-site areas and areas which remain undisturbed by construction activity must be included unless runoff from these areas is diverted away from the sediment settling pong and is not co-mingled with sediment laden runoff. The depth of the sediment settling pond must be less that or equal to five feet. The configuration between inlets and outlets of the basin must provide at least two units of length for each one unit of width (>2:1 length: width ratio). Sediment must be removed from the sediment settling pond when the design capacity has been reduced by 40%. (This is typically reached when sediment occupies one-half of the basin depth). Any dredged sediments placed on site must be immediately seeded and mulched or hauled off site to an appropriate location. When designing sediment settling ponds, the applicant must consider public safety as a design factor for the sediment basin and alternative sediment controls must be used where site limitations would preclude a safe design. The use of a combination of sediment and erosion control measures in order to achieve maximum pollutant removal is encouraged.
(c) The city may require sediment settling basins or traps for smaller disturbed areas where deemed necessary. Sediment settling basins or traps whether permanent or temporary must be provided and continue to function until final stabilization of the site is achieved. Temporary sediment settling basins or traps may be removed following final stabilization of the site.
(Ord. 15-O-2820, passed 5-19-2015)