(A) Construction timing. Detention facilities in a particular basin shall be constructed in the early stages of development to minimize excess flow during construction, and to collect sediment, top soil and other construction related materials which could flow into the drainage system during development. Upon the completion of the land development, the detention facilities are to be restored to the original cross-section illustrated on the development plans which the City Engineer previously approved. The City Engineer shall approve the manner and disposition of any deposits removed from the facility. The bond for development will not be released until the City Engineer has certified that the detention facility has been restored to its original design cross-section. If parking lots or other detention facilities are not available at the initiation of construction, the developer shall provide alternatives to minimize flooding and degradation of water quality until the permanent detention facilities are constructed.
(B) Performance standards.
(1) Stormwater channel location.
(a) In only a few special occasions will stormwater be allowed to be transported in above-ground channels within a development. For example, these channels may be centered on lot lines or entirely within the rear yards of a single row of lots or parcels.
(b) In each case, a drainage easement with sufficient width to facilitate maintenance and design flow shall be provided and illustrated on the plat. The plat shall also include restriction on use of the easements so that the channel is free and clear of all permanent and temporary structures, trees, bushes and other vegetation.
(2) Storm sewer outfall. The storm sewer outfall shall be designed to adequately protect against erosion and scouring by means of energy dissipators, gabions, rip-rap, falls or City Engineer-approved alternatives.
(3) Manholes. All utility manholes, except storm sewer manholes constructed in an area designed for the storage or passage of stormwater, shall be provided with a watertight manhole cover.
(C) Cooperative drainage structures. Whenever possible, developers are encouraged to construct storage facilities which serve more than one development. In cases where this is deemed beneficial, the city may consider and determine the terms and conditions of a recapture agreement to establish financing and contractual repayment arrangements for the construction of a detention/retention facility designed to serve the subject development and adjoining properties. The agreement is subject to City Council approval. If the development is outside the city limits, the reimbursement shall be made when the entire development is annexed or in compliance with other terms and conditions approved by the City Council.
(Ord. 10-3277, § 5-3.3, passed 1-4-2010)