§ 105-6. 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 section 105-6(b).

(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.

(2)

Accessory structures. As an alternative to the fill requirements of section 105-6(b)(1), structures accessory to the uses identified in section 105-6(a) may be permitted to be internally/wet floodproofed to the FP3 or FP4 floodproofing classifications in the state building code, provided that:

a.

The accessory structure constitutes a minimal investment, does not exceed 576 square feet in size, and is only used for parking and storage.

b.

All portions of floodproofed accessory structures below the regulatory flood protection elevation must be:

1.

Adequately anchored to prevent flotation, collapse or lateral movement and designed to equalize hydrostatic flood forces on exterior walls.

2.

Be constructed with materials resistant to flood damage.

3.

Must have all service utilities be water-tight or elevated to above the regulatory flood protection elevation.

c.

Designs for meeting this requirement must either be certified by a registered professional engineer or meet or exceed the following criteria:

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.

3.

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 section 105-6(b)(1) of this article, or if allowed as a conditional use under section 105-6(c)(3) below.

4.

The storage of any materials or equipment must be elevated on fill to the regulatory flood protection elevation.

5.

All service utilities, including ductwork, must be elevated or water-tight to prevent infiltration of floodwaters.

6.

All fill must be properly compacted and the slopes must be properly protected by the use of riprap, vegetative cover or other acceptable method.

7.

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 /emergency evacuation plan acceptable to the city council.

8.

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 (one percent chance) flood.

9.

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 floodplain location.

10.

Manufactured homes and recreational vehicles must meet the standards of section 105-9 of this article.

(c)

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 section 105-10(d) of this article.

(1)

Any structure that is not elevated on fill or floodproofed in accordance with sections 105-6(b)(1) and (2) of this article.

(2)

Storage of any material or equipment below the regulatory flood protection elevation.

(3)

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 section 105-6(b)(1) of this article.

(d)

Standards for flood fringe conditional uses.

(1)

The standards listed in sections 105-6(b)(3) through (9) apply to all conditional uses.

(2)

Residential basements, as defined under section 105-2(f) of this article are not allowed below the regulatory flood protection elevation.

(3)

All areas of nonresidential structures, including basements, to be placed below the regulatory flood protection elevation must be structurally dry floodproofed, meeting 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.

(4)

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.

a.

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 (one percent chance) flood event.

b.

The plan must be prepared and certified by a registered professional engineer or other qualified individual acceptable to the city council.

c.

The plan may incorporate alternative procedures for removal of the material from the floodplain if adequate flood warning time exists.

(5)

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.

(Ord. No. 423, § 1, 2-13-2017)