Agenda - Planning Commission - 07/27/2023

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1 if the city has approved a plan that assures removal of the materials from the floodway 2 based upon the flood warning time available. 3 (3) Accessory structures: 4 a. Accessory structures must not be designed for human habitation. 5 b. Accessory structures, if permitted, must be constructed and placed on the building site 6 so as to offer the minimum obstruction to the flow of flood waters: 7 1. Whenever possible, structures must be constructed with the longitudinal axis 8 parallel to the direction of flood flow; and 9 2. So far as practicable, structures must be placed approximately on the same flood 10 flow lines as those of adjoining structures. 11 c. Accessory structures must be elevated on fill or structurally dry floodproofed in 12 accordance with the FP-1 or FP-2 floodproofing classifications in the Minnesota State 13 Building Code. All floodproofed accessory structures must meet the following additional 14 standards: 15 1. The structure must be adequately anchored to prevent flotation, collapse or 16 lateral movement and designed to equalize hydrostatic flood forces on exterior 17 walls; and 18 2. Any mechanical and utility equipment in the structure must be elevated to or 19 above the regulatory flood protection elevation or properly floodproofed. 20 d. As an alternative, an accessory structure may be internally/wet floodproofed to the FP-3 or 21 FP-4 floodproofing classifications in the Minnesota State Building Code, provided the 22 accessory structure constitutes a minimal investment and does not exceed 576 square feet in 23 size. A detached garage may only be used for parking of vehicles and limited storage. All 24 structures must meet the following standards: 25 1. To allow for the equalization of hydrostatic pressure, there must be a minimum of two 26 "automatic" openings in the outside walls of the structure, with a total net area of not 27 less than one square inch for every square foot of enclosed area subject to flooding; 28 and 29 2. There must be openings on at least two sides of the structure and the bottom of all 30 openings must be no higher than one foot above the lowest adjacent grade to the 31 structure. Using human intervention to open a garage door prior to flooding will not 32 satisfy this requirement for automatic openings. 33 (4) Structural works for flood control that will change the course, current or cross section of 34 protected wetlands or public waters are subject to the provisions of Minn. Stats. § 103G.245. 35 (5) A levee, dike or floodwall constructed in the floodway must not cause an increase to the one 36 percent chance or regional flood. The technical analysis must assume equal conveyance or 37 storage loss on both sides of a stream. 38 (6) Floodway developments must not adversely affect the hydraulic capacity of the channel and 39 adjoining floodplain of any tributary watercourse or drainage system. 40 41 924 Flood Fringe District (FF) 42 (A) Permitted uses. Permitted uses are those uses of land or structures allowed in the underlying zoning 43 district(s) that comply with the standards in subsection (b) below. 44 (B) Standards for flood fringe permitted uses. 45 (1) All structures, including accessory structures, must be elevated on fill so that the lowest floor, 46 as defined, is at or above the regulatory flood protection elevation. The finished fill elevation 47 for structures must be no lower than one foot below the regulatory flood protection elevation 48 and the fill must extend at the same elevation at least 15 feet beyond the outside limits of the 49 structure. Page 122 of 160