§ 419. Areas Subject to Flooding.
The boundaries of special flood hazard areas shall be identified by referencing the most current FEMA Flood Insurance Rate Maps (FIRM), an approved Letter of Map Revision (LOMR) or an approved Letter of Map Amendment (LOMA).
The boundaries of any special flood hazard area shall be clearly denoted on all development plans for parcels subject to flooding. Said boundaries shall be determined using a site specific, topographic survey of the parcel and the appropriate FIRM, LOMR, or LOMA.
On those parcels for which no base flood elevation (BFE) has been developed, it shall be the responsibility of the owner to have a registered professional engineer or hydrologist to establish a BFE.
On-site topographic surveys shall be performed to locate the precise floodplain line on a parcel prior to any development. The survey shall use the flood profile contained in the sources listed above or, if no such profile exists, by performing standard runoff calculations such as those contained in Standards and Specifications for Soil Erosion and Sediment Control, prepared by the Natural Resources Conservation Service.
419.01. Permanent open space. All such areas shall be permanent open space. No uses or improvements other than those permitted herein shall be permitted in any area consisting of floodway as defined by this Ordinance.
419.02. Permitted uses. The following uses are permitted within the floodway fringe as a matter of right:
A.
All uses that are permitted in designated open spaces.
B.
All uses that are classified as agriculture, nurseries, and outdoor recreation.
C.
Piers, bridges and bridge approaches, picnic shelters, and stormwater detention facilities, so long as the building permit application shows that a licensed engineer has certified that such structures are designed to withstand the forces exerted by the 100-year flood event at that location.
419.03. Building Elevation. All other buildings or any residential, institutional, office, commercial and entertainment, commercial recreation, recreational rental dwelling, or nursery uses (other than those specifically named in this Section) may be permitted as conditional uses pursuant to Section 903, provided that all habitable floor area shall be raised so that no floor, or its structural supports, or any utility line has less than one (1) foot of clearance between its lowest point and the 100-year flood elevation. Any reduction of cross-sectional area due to vertical supporting members shall be offset by compensatory storage. Vehicular access to such structures shall be at or higher than the 100 year base flood elevation (BFE).
Exceptions to 419.03 above may be as follows subject to the approval of the City Engineer:
A.
A non-residential building may have its finished floor elevation below the BFE as long as it fully complies with FEMA requirements.
B.
A non-residential building may have parking or parking access below BFE as long as it fully complies with FEMA requirements.
Note: Evidence of full compliance with FEMA requirements must be provided at time of submission.
419.04. Installation of fill materials. Fill may be placed within the floodway fringe only when allowed as a conditional use pursuant to Section 903 and approved by the City Engineer. An application for such conditional use shall be accompanied by detailed fill plans, showing existing and proposed conditions. If a structure is to be placed on the fill, the plans shall show the structure as well. In considering the application, the Planning Commission, in consultation with the City Engineer, shall determine whether the proposed fill meets the general standards set forth in Section 903, and the following additional standards:
A.
The cross-sectional area of a riverine floodplain shall not be reduced by more than two and one-half (2 ½) percent on either side of the centerline of the watercourse; an inland depressional floodplain may have its location and contours altered through cut and fill over 30 percent of its surface area.
B.
Compensatory storage shall be provided to offset the storage lost through the filling.
C.
All changes in velocity, depth of flood elevation, or storage shall be limited to the property owners who have been granted flood or flow easements, provided that in no event shall an increase in flood elevation be permitted if it would affect any existing building or bring any building to within one (1) foot of the flood elevation.
D.
In no instance shall the depth of fill in a riverine floodplain exceed five (5) feet, nor shall any fill be placed within 50 feet of the top of the stream bank or in a location which might be endangered by or accelerate a meander. In an inland depressional floodplain the depth of fill measured from the natural grade to the new surface shall not exceed five (5) feet.
E.
Fill shall consist of soil or rock materials only; sanitary landfills shall not be permitted in the floodplain. Further, all fill areas shall be stabilized with material that will insure and protect against erosion hazards, undercutting, and undermining.
419.05. Filling in Floodway. No filling in the floodway shall be permitted except upon review and recommendation of the City Engineer and/or in conjunction with a future adopted Flood Damage Prevention Ordinance.
419.06. Structural anchoring. Any structure placed in the floodplain shall be anchored firmly to prevent floodwaters from carrying it downstream. Such anchoring shall be sufficient to withstand a flood velocity of six (6) feet per second. The Planning Commission shall require the applicant to submit the written opinion of a registered professional engineer that the proposed structural design meets this standard.