§ 30-71. General standards.

(a)

All new residential, nonresidential and manufactured home structures, and any substantial improvements related to the same shall have the minimum lowest floor elevation be one foot above the higher of the following four measurements:

(1)

Base flood elevation as determined by the latest flood insurance rate map (FIRM) as issued by FEMA;

(2)

Center line of the nearest street across from or adjacent to the structure;

(3)

Top of the nearest upstream or downstream sanitary sewer manhole where a community or municipal system is provided; or

(4)

Highest recorded historical or modeled (100-year) inundation levels.

(b)

All mechanical equipment must also comply with the above minimum lowest floor elevation requirements.

(c)

Should the above freeboard calculation requirement result in an unreasonable elevation, a waiver may be requested.

(d)

If the nonresidential property is in a floodway, no development is allowed in the floodway.

(e)

A licensed land surveyor or engineer will be required to certify numbers two and three above through the use of the following freeboard elevation form. Note: "Freeboard Elevation Form" shall be available from city hall, the city planning division, and shall be used in determinations relative to this section.

(f)

The plat may state that, in lieu of elevating the nonresidential structure as required by the above freeboard calculation the building may be floodproofed as certified by a state licensed engineer or architect and approved by the floodplain administrator.

In all areas of special flood hazards the following provisions are required for all new construction and substantial improvements:

(1)

All new construction or substantial improvements shall be designed (or modified) and adequately anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;

(2)

All new construction or substantial improvements shall be constructed by methods and practices that minimize flood damage;

(3)

All new construction or substantial improvements shall be constructed with materials resistant to flood damage;

(4)

All new construction or substantial improvements shall be constructed with electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding;

(5)

All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system;

(6)

New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system and discharge from the systems into flood waters; and,

(7)

On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

(8)

Fill or other materials placed within a known flood hazard or floodplain shall be protected against erosion. Acceptable means of protection include but are not limited to riprap, vegetation covers, hydro-mulch, erosion control matting or bulkheading. See subsection (10) of this section for information on proposed fill in floodways as defined by the latest Federal Emergency Management Agency flood insurance rate map.

(9)

The city shall not permit the development of any land in a flood hazard area where such land is found to be incompatible with its proposed use due to poor drainage, flooding or other factors which would make the area vulnerable to flood damages that could pose a potential hazard to public health and safety. A development proposed within a floodplain being identified as such by the latest edition flood insurance rate maps shall be in accordance with the applicable regulatory agencies.

(10)

Any development that fills or modifies a designated special flood hazard area must mitigate that development activity volumetrically. The volume of any proposed fill material or modification below the base flood elevation and above natural grade shall be calculated and documented. Mitigation activities shall restore that volume to achieve an effective "zero net fill" of the pre-development storage capacity of the special flood hazard area. The development shall accept stormwater during a 100-year (one percent) storm event, both from on-site and off-site, such that post-development conditions provide storage volume equal to the pre-development storage volume, as measured in acre-feet. If the stormwater retention/detention facility is used as a storage mitigation area, the storage volume shall be calculated as the volume above the static water surface elevation of the facility.

(11)

A flood plain analysis shall be required for any development of five acres or more (whether or not comprising 50 or more lots), or 50 or more lots (whether or not comprising five acres or more), located within a designated special flood hazard area. The complete analysis must be conducted after preliminary plat approval by the city.

(12)

Any flood plain impact analysis conducted for a development located in a designated special flood hazard area zone "A" shall include, as an integral part of the flood plain impact analysis, a base flood elevation determination in accordance with FEMA document "Managing Floodplain Development in Approximate Zone A Area".

(Ord. No. 2018-017 , § 2, 12-17-2018)