(A) The applicant shall install or construct, on or for the proposed land disturbing or development activity, all stormwater management facilities necessary to manage:
(1) Storm peak discharge rates to pre-project rates for the 2.0-yr, 10-yr, and 100-yr 24-hour storm events.
(2) Sites that disturb less than one acre shall be designed to control runoff rate so as to not cause downstream flooding or erosion.
(3) Sites that disturb one acre or more shall provide permanent BMPs, with highest preference given to green infrastructure techniques and practices necessary to meet the following conditions on the site of construction activity to the maximum extent practicable.
(a) Stormwater release rates and volume from the site on an annual average basis shall not increase over the pre-development 24-hour two year, ten year, and 100 year peak storm discharges rates, based on the last ten years of how that land was used. Also accelerated channel erosion must not occur as a result of the proposed activity.
(b) Permanent best management practices for sites where the sum of new and reconstructed impervious surface is one or more acres shall be designed to meet the requirements for post-construction stormwater management as described in the MN Small Municipal Separate Storm Sewer Systems General Permit No. MNR040000 in place at the time of submittal.
(c) Applicants shall provide documentation showing rate, volume, and water quality compliance. Calculations shall be by a methodology listed in the MPCA Stormwater Manual or other method approved by the city.
(B) Oil and grease control. Where the potential for pollution by oil, grease, or both exists, the city may require installation of an oil and grease removal device designed to handle the volume and type of material anticipated.
(C) Performance security. Prior to approval of permits for construction, the applicant may be required to submit an agreement to construct such required physical improvements, to dedicate property or easements, to provide performance security (letter of credit or performance bond), and to comply with such conditions as may have been agreed to.
(D) Failure to complete. If the applicant fails to complete the required stormwater improvements within 24-months of beginning construction of the project they are intended to mitigate, the city may make provisions to complete the required stormwater improvements or to provide equivalent downstream treatment. The city shall use any performance security held for the work or may utilize special assessments as provided in M.S. § 429 to reimburse itself for costs associated with this work.
(E) Where the City Council authorizes the construction of private stormwater management facilities, the applicant shall designate the responsible party for inspection and maintenance of all private stormwater management facilities in an agreement to be recorded against the properties being developed. In addition, the agreement shall provide for:
(1) Description of anticipated maintenance activities and frequency.
(2) Access in perpetuity for inspection of the facilities by the Director of Public Works or his/her designee.
(3) Access in perpetuity for maintenance of the facilities should the Director of Public Works or his/her designee find that stormwater facility maintenance is required and upon written notice the property owners fail to take corrective action with the cost of such maintenance to be paid by the property owner.
(4) If the expense is not paid, the expense will be made a special assessment against the property concerned in accordance with M.S. § 429.061 and other pertinent statutes for certification to the County Auditor and collection along with the current taxes the following year or in annual installments, as the City Council may determine in each case.
(F) Removal or alteration of Structural Stormwater Best Management Practices. Structural Stormwater Best Management Practices installed to fulfill the requirements of this chapter shall be maintained in compliance with the approved maintenance plan. Where no plan is in place they shall be maintained in compliance with accepted Industry Standard and Minnesota Pollution Control Agency recommendations. No Structural Stormwater Best Management Practices shall be removed or altered in such a way to decrease structural Stormwater Best Management Practices effectiveness without:
(1) Authorization of the Director of Public Works or his/her designee; and
(2) Providing new or improved Structural Stormwater Best Management Practices providing or exceeding that amount lost due to the alteration or removal.
(Ord. 82, 4th Series, passed 12-5-2016; Am. Ord. 153, 4th Series, passed 10-3-2022)