Agenda - Planning Commission - 10/15/2015

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(3) Accessory Structures: a. Accessory structures must not be designed for human habitation. b. Accessory structures, if permitted, must be constructed and placed on the building site so as to offer the minimum obstruction to the flow of flood waters: 1. Whenever possible, structures must be constructed with the longitudinal axis parallel to the direction of flood flow; and 2. So far as practicable, structures must be placed approximately on the same flood flow lines as those of adjoining structures. c. Accessory structures must be elevated on fill or structurally dry floodproofed in accordance with the FP -1 or FP -2 floodproofing classifications in the MN State Building Code. All floodproofed accessory structures must meet the following additional standards: 1. The structure must be adequately anchored to prevent flotation, collapse or lateral movement and designed to equalize hydrostatic flood forces on exterior walls; and 2. Any mechanical and utility equipment in the structure must be elevated to or above the regulatory flood protection elevation or properly floodproofed. d. As an alternative, an accessory structure may be internally/wet floodproofed to the FP -3 or FP -4 floodproofing classifications in the MN State Building Code, provided the accessory structure constitutes a minimal investment and does not exceed 576 square feet in size. A detached garage may only be used for parking of vehicles and limited storage. All structures must meet the following standards: 1. 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 2. 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. (4) 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 Minnesota Statutes, Section 103G.245. (5) 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. (6) Floodway developments must not adversely affect the hydraulic capacity of the channel and adjoining floodplain of any tributary watercourse or drainage system. Sec. 117-184. — Flood Fringe District (FF) (a) Permitted uses. Permitted uses are those uses of land or structures allowed in the underlying zoning district(s) that comply with the standards in subsection (b) below. (b) Standards for flood fringe permitted uses. (1) All structures, including accessory structures, must be elevated on fill so that the lowest floor, as defined, is at or above the regulatory flood protection elevation. The finished fill elevation for structures must be no lower than one foot below the regulatory flood protection elevation and the fill must extend at the same elevation at least 15 feet beyond the outside limits of the structure. a. All service utilities, including ductwork, must be elevated or water -tight to prevent infiltration of floodwaters. b. As an alternative to elevation on fill, an accessory structure that constitutes a minimal investment and that does not exceed 576 square feet in size may be internally floodproofed in accordance with 117-183 (d)(3).