Subd. 1. Permitted uses.
A. Permitted uses shall be those uses of land or structures listed as permitted uses in the underlying zoning districts.
B. All permitted uses shall comply with the standards for flood fringe permitted uses listed in Subd. 2 below and the standards for flood fringe conditional uses listed in Subd. 3 below.
Subd. 2. Standards for flood fringe permitted uses.
A. All structures, including accessory structures, must be elevated on fill so that the lowest floor including basement floor is at or above the regulatory flood protection elevation. The finished fill elevation for structures shall be no lower than one foot below the regulatory flood protection elevation and the fill shall extend at an elevation at least 15 feet beyond the outside limits of the structure erected thereon.
B. As an alternative to elevation on fill, accessory structures that constitute a minimal investment and that do not exceed 576 square feet at its largest projection may be internally flood-proofed in accordance with § 12.13, Subd. 4, Subpar. D.
C. The cumulative placement of fill in excess of 250 cubic yards of fill on the parcel shall be allowable only as a conditional use unless the fill is specifically intended to elevate a structure in accordance with Subpar. A above.
D. The storage of any materials or equipment shall be elevated on fill to the regulatory flood protection elevation.
E. The provisions of Subd. 5 below shall apply.
Subd. 3. Conditional uses. The following uses may be allowed as conditional uses following the procedure set forth in § 12.26 and further subject to the standards in Subd. 5 below.
A. Any structure that is not elevated on fill or flood-proofed in accordance with Subd. 2, Subpar. A and B above.
B. Accessory structures exceeding the 576 square feet, as specified in Subd. 2, Subpar. B above in accordance with the flood proofing standards of § 12.13, Subd. 4, Subpar. D.
C. Storage of any material or equipment below the regulatory flood protection elevation.
D. The cumulative placement of more than 250 cubic yards of fill when the fill is not being used to elevate a structure.
Subd. 4. Standards for flood fringe conditional uses.
A. Alternative elevation methods other than the use of fill may be utilized to elevate a structure’s lowest floor above the regulatory flood protection elevation. These alternative methods may include the use of stilts, pilings, parallel walls and the like or above- grade, enclosed areas such as crawl spaces or tuck-under garages. The base or floor of an enclosed area shall be considered above-grade and not a structure’s basement or lowest floor if:
1. If the enclosed area is above-grade on at least one side of the structure;
2. Is designed to internally flood and is constructed with flood resistant materials; and
3. Is used solely for parking of vehicles, building access or storage.
B. The above-noted alternative elevation methods are subject to the following additional standards:
1. Design and certification. The structure’s design and as-built condition must be certified by a registered professional engineer or architect as being in compliance with the general design standards of the State Building Code and, specifically, that all electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities must be at or above the regulatory flood protection elevation or be designed to prevent flood water from entering or accumulating within these components during times of flooding.
2. Specific standards for above-grade, enclosed areas. Above-grade, fully enclosed areas such as crawl spaces or tuck-under garages must be designed to internally flood and the design plans must stipulate:
a. The minimum area of openings in the walls where internal flooding is to be used as a flood-proofing technique. There shall be a minimum of two openings on at least two sides of the structure and the bottom of all openings shall be no higher than one foot above grade. The automatic openings shall have a minimum net area of not less than one square inch for every square foot of enclosed area subject to flooding unless a registered professional engineer or architect certifies that a smaller net area would suffice. The automatic openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of flood waters without any form of human intervention; and
b. That the enclosed area will be designed of flood resistant materials in accordance with the FP-3 or FP-4 classifications in the State Building Code and shall be used solely for building access, parking of vehicles or storage.
C. Basements, as defined in § 12.10, Subd. 4, shall be 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 flood-proofed in accordance with Subpar. D below.
D. All areas of non-residential structures including basements to be placed below the regulatory flood protection elevation shall be flood-proofed in accordance with the structurally dry flood-proofing classifications in the State Building Code. Structurally dry flood- proofing must meet the FP-1 or FP-2 flood-proofing classification in the State Building Code and this shall require making the structure watertight with the walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. Structures flood-proofed to the FP-3 or FP-4 classification shall not be permitted.
E. When at any one time more than 250 cubic yards of fill or other similar material is located on a parcel for such activities as on-site storage, landscaping, sand and gravel operations, landfills, roads, dredge spoil disposal or construction of flood control works, an erosion/sedimentation control
plan must be submitted.
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 1% or regional flood event.
2. The plan must be prepared and certified by a registered professional engineer or other qualified individual acceptable to the governing body.
3. The plan may incorporate alternative procedures for removal of the material from the flood plain if adequate flood warning time exists.
F. 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. Storage of other materials or equipment may be allowed if readily removable from the area within the time available after a flood warning and in accordance with a plan approved by the governing body.
G. The provisions of Subd. 5 below shall also apply.
Subd. 5. Standards for all flood fringe uses.
A. All new principal structures must have vehicular access at or above an elevation not more than two feet below the regulatory flood protection elevation. If a variance to this requirement is granted, the Board of Adjustment must specify limitations on the period of use or occupancy of the structure for times of flooding and only after determining that adequate flood warning time and local flood emergency response procedures exist.
B. Commercial uses. Accessory land uses, such as yards, railroad tracks and parking lots may be at elevations lower than the regulatory flood protection elevation. However, a permit for the facilities to be used by the employees or the general public shall not be granted in the absence of a flood warning system that provides adequate time for evacuation if the area would be inundated to a depth and velocity such that when multiplying the depth (in feet) times velocity (in feet per second) the product number exceeds four upon occurrence of the regional flood.
C. Manufacturing and industrial uses. Measures shall be taken to minimize interference with normal plant operations especially along streams having protracted flood durations. Certain accessory land uses such as yards and parking lots may be at lower elevations subject to requirements set out in Subpar. B above. In considering permit applications, due consideration shall be given to needs of an industry whose business requires that it be located in flood plain areas.
D. Fill shall be properly compacted and the slopes shall be properly protected by the use of riprap, vegetative cover or other acceptable method. The Federal Emergency Management Agency (FEMA) has established criteria for removing the special flood hazard area designation for certain structures properly elevated on fill above the 100-year flood elevation - FEMA’s requirements incorporate specific fill compaction and side slope protection standards for multi-structure or multi-lot developments. These standards should be investigated prior to the initiation of site preparation if a change of special flood hazard area designation will be requested.
E. Flood plain developments shall not adversely affect the hydraulic capacity of the channel and adjoining flood plain of any tributary watercourse or drainage system.
F. Standards for recreational vehicles are contained in § 12.23, Subd. 3.
G. All manufactured homes and those recreational vehicles not meeting the exemption criteria of § 12.23, Subd. 3 must be securely anchored to an adequately anchored foundation system that resists flotation, collapse and lateral movement. Methods of anchoring may include, but are not to be limited to use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable state or local anchoring requirements for resisting wind forces.
(`80 Code, § 12.14) (Ord. 238, Second Series, passed 4-30-91; Am. Ord. 602, passed 8-19-13)