(A) Districts.
(1) Floodway District. The Floodway District includes those areas within Zones AE that have a floodway delineated as shown on the Flood Insurance Rate Map adopted in § 152.491. For lakes, wetlands and other basins within Zones AE that do not have a floodway delineated, the Floodway District also includes those areas that are at or below the ordinary high water level as defined in M.S. § 103G.005, Subd. 14.
(2) Flood Fringe District. The Flood Fringe District includes areas within Zones AE that have a floodway delineated on the Flood Insurance Rate Map adopted in § 152.491, but are located outside of the floodway. For lakes, wetlands and other basins within Zones AE that do not have a floodway delineated, the Flood Fringe District also includes those areas below the 1% annual chance (100-year) flood elevation but above the ordinary high water level as defined in M.S. § 103G.005, Subd. 14.
(3) General Flood Plain District. The General Flood Plain District includes those areas within Zones A, AE, or AH that do not have a delineated floodway as shown on the Flood Insurance Rate Map adopted in § 152.491.
(B) Applicability. Within the Flood Plain Districts established in this subchapter, the use, size, type and location of development must comply with the terms of this subchapter and other applicable regulations. In no cases shall flood plain development adversely affect the efficiency or unduly restrict the capacity of the channels or floodways of any tributaries to the main stream, drainage ditches, or any other drainage facilities or systems. All uses not listed as permitted uses or conditional uses in divisions (C), (D) and (E) below are prohibited. In addition, critical facilities, as defined in § 152.008, are prohibited in all Flood Plain Districts.
(C) Floodway District (FW).
(1) Permitted uses. The following uses, subject to the standards set forth in division (C)(2) below and § 152.514, are permitted uses if otherwise allowed in the underlying zoning district or any applicable overlay district:
(a) General farming, pasture, grazing, outdoor plant nurseries, horticulture, truck farming, forestry, sod farming, and wild crop harvesting.
(b) Industrial-commercial loading areas, parking areas, and airport landing strips.
(c) Open space uses, including but not limited to private and public golf courses, tennis courts, driving ranges, archery ranges, picnic grounds, boat launching ramps, swimming areas, parks, wildlife and nature preserves, game farms, fish hatcheries, shooting preserves, hunting and fishing areas, and single or multiple purpose recreational trails.
(d) Residential lawns, gardens, parking areas, and play areas.
(e) Railroads, streets, bridges, utility transmission lines and pipelines, provided that the Department of Natural Resources Area Hydrologist is notified at least ten days prior to issuance of any permit.
(2) Standards for Floodway permitted uses.
(a) The use must have a low flood damage potential.
(b) The use must not obstruct flood flows or cause any increase in flood elevations and must not involve structures, obstructions, or storage of materials or equipment.
(c) Any facility that will be used by employees or the general public must be designed with a flood warning system that provides adequate time for evacuation if the area is inundated to a depth and velocity such that the depth (in feet) multiplied by the velocity (in feet per second) would exceed a product of four upon occurrence of the regional (1% chance) flood.
(d) No on-site sewage treatment, holding tanks or water supply systems are permitted in the floodway.
(3) Conditional uses. The following uses may be allowed as conditional uses following the standards and procedures set forth in § 152.519 and further subject to the standards set forth in division (C)(4) below, if otherwise allowed in the underlying zoning district or any applicable overlay district.
(a) Structures accessory to the uses listed in divisions (C)(1)(a) through (c) and the uses listed in divisions (C)(3)(b) and (c).
(b) Extraction and storage of sand, gravel, and other materials.
(c) Marinas, boat rentals, docks, piers, wharves, and water control structures.
(d) Storage yards for equipment, machinery, or materials.
(e) Placement of fill or construction of fences that obstruct flood flows. Farm fences, as defined in § 152.008, are permitted uses as it relates to this section.
(f) Travel-ready recreational vehicles meeting the exception standards in § 152.514(F)(2).
(g) Levees or dikes intended to protect agricultural crops for a frequency flood event equal to or less than the ten-year frequency flood event.
(4) Standards for Floodway conditional uses.
(a) All uses. A conditional use must not cause any increase in the stage of the 1% chance or regional flood or cause an increase in flood damages in the reach or reaches affected.
(b) Fill; storage of materials and equipment:
1. The storage or processing of materials that are, in time of flooding, flammable, explosive, or potentially injurious to human, animal, or plant life is prohibited.
2. Fill, dredge spoil, and other similar materials deposited or stored in the flood plain 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.
3. 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 Council has approved a plan that ensures removal of the materials from the floodway based upon the flood warning time available.
(c) Accessory structures. Accessory structures, as identified in division (C)(3)(a) above, 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 FP1 or FP2 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 FP3 or FP4 floodproofing classifications in the State Building Code, provided the accessory structure constitutes a minimal investment and does not exceed 576 square feet in size. Designs for meeting this requirement must either be certified by a registered professional engineer or meet or exceed the following criteria: 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 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) 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.
(e) 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) Floodway developments must not adversely affect the hydraulic capacity of the channel and adjoining flood plain of any tributary watercourse or drainage system.
(D) Flood Fringe District (FF).
(1) Permitted uses. Permitted uses are those uses of land or structures allowed in the underlying zoning district(s) that comply with the standards in division (D)(2) below. If no pre-existing, underlying zoning districts exist, then any residential or nonresidential structure or use of a structure or land is a permitted use provided it does not constitute a public nuisance.
(2) Standards for Flood Fringe permitted uses.
(a) Except for the structures mentioned in § 152.514(D), only non-habitable accessory structures constructed with less than 120 square feet, fences, or docks for the personal use of the resident(s) of the principal structure that are constructed with flood resistant material to the regulatory flood protection elevation in accordance with the flood proofing classification of the State Building Code may be permitted in the flood fringe, if permitted in the underlying district. No accessory structure may be constructed on the property that will increase flood elevations. 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.
(b) Accessory structures. As an alternative to the fill requirements of division (D)(2)(a) above, structures accessory to the uses identified in division (D)(1) above may be permitted to be internally/wet floodproofed to the FP3 or FP4 floodproofing classifications in the State Building Code, provided that:
1. The accessory structure constitutes a minimal investment, does not exceed 576 square feet in size, and is only used for parking and storage.
2. All portions of floodproofed accessory structures below the regulatory flood protection elevation must be:
a. Adequately anchored to prevent flotation, collapse or lateral movement and designed to equalize hydrostatic flood forces on exterior walls;
b. Be constructed with materials resistant to flood damage; and
c. Must have all service utilities be water-tight or elevated to above the regulatory flood protection elevation.
3. Designs for meeting this requirement must either be certified by a registered professional engineer or meet or exceed the following criteria: 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 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.
(c) The cumulative placement of fill or similar material on a parcel must not exceed 1,000 cubic yards, unless the fill is specifically intended to elevate a structure in accordance with division (D)(2)(a) above, or if allowed as a conditional use under division (D)(3)(c) below.
(d) The storage of any materials or equipment must be elevated on fill to the regulatory flood protection elevation.
(e) All service utilities, including ductwork, must be elevated or water-tight to prevent infiltration of floodwaters.
(f) The storage or processing of materials that are, in time of flooding, flammable, explosive, or potentially injurious to human, animal, or plant life is prohibited.
(g) All fill must be properly compacted and the slopes must be properly protected by the use of riprap, vegetative cover or other acceptable method.
(h) All new principal structures must have vehicular access at or above an elevation not more than two feet below the regulatory flood protection elevation, or must have a flood warning or emergency evacuation plan acceptable to the City Council.
(i) Accessory uses such as yards, railroad tracks, and parking lots may be at an elevation lower than the regulatory flood protection elevation. However, any facilities used by employees or the general public must be designed with a flood warning system that provides adequate time for evacuation if the area is inundated to a depth and velocity such that the depth (in feet) multiplied by the velocity (in feet per second) would exceed a product of four upon occurrence of the regional (1% chance) flood.
(j) Interference with normal manufacturing/industrial plant operations must be minimized, especially along streams having protracted flood durations. In considering permit applications, due consideration must be given to the needs of industries with operations that require a flood plain location.
(3) Conditional uses. The following uses and activities may be allowed as conditional uses, if allowed in the underlying zoning district(s) or any applicable overlay district, following the procedures in § 152.519.
(a) Any structure that is not elevated on fill or floodproofed in accordance with division (D)(2) (a) and (b) above.
(b) Storage of any material or equipment below the regulatory flood protection elevation.
(c) The cumulative placement of more than 1,000 cubic yards of fill when the fill is not being used to elevate a structure in accordance with division (D)(2)(a) above.
(4) Standards for Flood Fringe conditional uses.
(a) The standards listed in divisions (D)(2)(c) through (j) apply to all conditional uses.
(b) Basements, as defined by § 152.008, are subject to the following:
1. Residential basement construction is not allowed below the regulatory flood protection elevation.
2. Non-residential basements may be allowed below the regulatory flood protection elevation provided the basement is structurally dry floodproofed in accordance with division (D)(4)(c) below.
(c) All areas of nonresidential structures, including basements, to be placed below the regulatory flood protection elevation must be floodproofed in accordance with the structurally dry floodproofing classifications in the State Building Code. Structurally dry floodproofing must meet the FP1 or FP2 floodproofing classification in the State Building Code, which requires making the structure watertight with the walls substantially impermeable to the passage of water and with structural components capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy.
(d) The placement of more than 1,000 cubic yards of fill or other similar material on a parcel (other than for the purpose of elevating a structure to the regulatory flood protection elevation) must comply with an approved erosion/sedimentation control plan.
1. The plan must clearly specify methods to be used to stabilize the fill on site for a flood event at a minimum of the regional (1% chance) flood event.
2. The plan must be prepared and certified by a registered professional engineer or other qualified individual acceptable to the City Council.
3. The plan may incorporate alternative procedures for removal of the material from the flood plain if adequate flood warning time exists.
(e) Storage of materials and equipment below the regulatory flood protection elevation must comply with an approved emergency plan providing for removal of such materials within the time available after a flood warning.
(E) General Flood Plain District (GF).
(1) Permitted uses.
(a) The uses listed in division (C)(1) above, Floodway District permitted uses, are permitted uses.
(b) All other uses are subject to the floodway/flood fringe evaluation criteria specified in division (E)(2) below. Division (C) above applies if the proposed use is determined to be in the Floodway District. Division (D) above applies if the proposed use is determined to be in the Flood Fringe District.
(2) Procedures for Floodway and Flood Fringe determinations.
(a) Upon receipt of an application for a permit or other approval within the General Flood Plain District, the Zoning Administrator must obtain, review and reasonably utilize any regional flood elevation and floodway data available from a federal, state, or other source.
(b) If regional flood elevation and floodway data are not readily available, the applicant must furnish additional information, as needed, to determine the regulatory flood protection elevation and whether the proposed use would fall within the Floodway or Flood Fringe District. Information must be consistent with accepted hydrological and hydraulic engineering standards and the standards in division (E)(2)(c) below.
(c) The determination of floodway and flood fringe must include the following components, as applicable:
1. Estimate the peak discharge of the regional (1% chance) flood.
2. Calculate the water surface profile of the regional flood based upon a hydraulic analysis of the stream channel and overbank areas.
3. Compute the floodway necessary to convey or store the regional flood without increasing flood stages more than one-half (0.5) foot. A lesser stage increase than 0.5 foot is required if, as a result of the stage increase, increased flood damages would result. An equal degree of encroachment on both sides of the stream within the reach must be assumed in computing floodway boundaries.
(d) The Zoning Administrator will review the submitted information and assess the technical evaluation and the recommended Floodway and/or Flood Fringe District boundary. The assessment must include the cumulative effects of previous floodway encroachments. The Zoning Administrator may seek technical assistance from a designated engineer or other expert person or agency, including the Department of Natural Resources. Based on this assessment, the Zoning Administrator may approve or deny the application.
(e) After the Floodway and Flood Fringe District boundaries have been determined, the Zoning Administrator must process the permit application consistent with the applicable provisions of divisions (C) and (D) above.
(Ord. 2000-936; Am. Ord. 2005-1033, passed 2-7-05; Am. Ord. 2016-1209, passed 10-10-16)