(A) All uses. A conditional use must not cause any increase in the regional flood elevations or cause an increase in flood damages in the reach or reaches affected.
(B) Fill; storage of materials and equipment.
(1) Fill, dredge spoil, and other similar materials deposited or stored in the floodplain must be protected from erosion by vegetative cover, mulching, riprap, or other acceptable method. Permanent sand and gravel operations and similar uses must be covered by a long-term site development plan.
(2) Temporary placement of fill, other materials, or equipment which would cause an increase to the stage of the 1% chance or regional flood may only be allowed if the city has approved a plan that assures removal of the materials from the floodway based upon the flood warning time available.
(C) Accessory structures. Accessory structures, as identified in § 153.067(A), may be permitted, provided that:
(1) Structures are not intended for human habitation;
(2) Structures will have a low flood damage potential;
(3) Structures will be constructed and placed so as to offer a minimal obstruction to the flow of flood waters;
(4) Service utilities, such as electrical and heating equipment, within these structures must be elevated to or above the regulatory flood protection elevation or properly floodproofed;
(5) Structures must be elevated on fill or structurally dry floodproofed in accordance with the FP-1 or FP-2 floodproofing classifications in the State Building Code. All floodproofed structures must be adequately anchored to prevent flotation, collapse, or lateral movement and designed to equalize hydrostatic flood forces on exterior walls.
(6) As an alternative, an accessory structure may be internally/wet floodproofed to the FP-3 or FP-4 floodproofing classifications in the State Building Code, provided the accessory structure constitutes a minimal investment. Designs for meeting this requirement must either be certified by a registered professional engineer or meet or exceed the following criteria:
(a) To allow for the equalization of hydrostatic pressure, there must be a minimum of two “automatic” openings in the outside walls of the structure, with a total net area of not less than one square inch for every square foot of enclosed area subject to flooding; and
(b) There must be openings on at least two sides of the structure and the bottom of all openings must be no higher than one foot above the lowest adjacent grade to the structure. Using human intervention to open a garage door prior to flooding will not satisfy this requirement for automatic openings.
(D) Change to waterways. Structural works for flood control that will change the course, current, or cross section of protected wetlands or public waters are subject to the provisions of M.S. § 103G.245, as it may be amended from time to time.
(E) Increased risk of flood. A levee, dike, or floodwall constructed in the floodway must not cause an increase to the 1% chance or regional flood. The technical analysis must assume equal conveyance or storage loss on both sides of a stream.
(F) Hydraulic capacity. Floodway developments must not adversely affect the hydraulic capacity of the channel and adjoining floodplain of any tributary watercourse or drainage system.
(Ord. 2017-03, passed 7-24-2017)