(A) System required.
(1) Every subdivision and land development shall be provided with a comprehensive stormwater management system which is adequate to serve the area and meets the requirements of this chapter, the stormwater management design regulations and other criteria of the city. Two separate and distinct drainage systems exist:
(a) A minor drainage system for collecting and transporting runoff from frequently occurring storms. It includes watercourses, streets, curbs and gutters, and underground storm sewers, manholes, catch basins, and culverts. This system's purpose is to lessen or eliminate inconveniences and safety and health hazards associated with frequent storms. Except where indicated otherwise, design criteria and requirements of this chapter are directed to the minor drainage system.
(b) A major drainage system for ensuring that stormwater runoff which exceeds the capacity of the minor drainage system has a route to follow that will not cause any loss of property or any loss of life. It must be recognized that the major drainage system exists even when it is not planned and whether or not physical facilities are intelligently located in respect to it.
(c) A stormwater quality control measure or BMP for treating stormwater in conformance with the requirement of this chapter.
(B) Rate of runoff.
(1) Developers are required to design improvements such that after development, the rate of stormwater runoff leaving the project area at strategic points is no more than if the project area had remained undeveloped. If necessary, detention/retention facilities shall be constructed to assure that this requirement is met.
(2) Where a portion of the project area contains existing development features such as buildings, streets, parking lots, sidewalks, driveways, and the like, and a permit application is made for additional development, the area to be considered in determining the rate of stormwater runoff shall be only that on which the additional development is sought. However, any development in the project area constructed after August 2, 1979 (the effective date of the requirement for restricting stormwater runoff to the rate prior to development) without an approved plan shall be considered as part of the additional development.
(3) The City Engineer may reduce or waive requirements for an individual detention/retention basin if a common or regional basin of adequate design is available or if the Utility is reasonably certain one will be constructed and if the major drainage system from the project area to such common or regional basin is such that the public health, safety, and welfare will not be in jeopardy.
If this option is exercised, the developer will be billed in accordance with the standard utility rate structure.
(4) Stormwater management systems will be designed for the ultimate use of the land and shall be capable of conveying runoff originating upstream as determined by the City Engineer.
(C) Easements. Where a public storm sewer, culvert, open channel, catch basin, inlet, manhole, post-construction storm water control measure or other public drainage structure lies outside the public right-of-way, easements of sufficient size as determined by the City Engineer shall be provided to assure easy access and maintenance.
(Ord. 04-1990, passed 3-5-90; Am. Ord. 14-2021, passed 8-2-21) Penalty, see § 51.99