Sec. 9.3.7. SFHA Based on Drainage Basin Study, Flood Study, and Flood Hazard Soils Standards

  1. Drainage Basin Study, Flood Study, and Flood Hazard Soils Floodway Standards
    The following provisions shall apply to those areas designated as floodways based on drainage basin studies or flood hazard soils:
    1. No encroachments, including fill, new construction, substantial improvements, and other developments shall be permitted unless:
      1. It is demonstrated that the proposed encroachment would not result in any increase in the flood levels during the occurrence of the base flood discharge, based on hydrologic and hydraulic analyses performed in accordance with standard engineering practice and presented to the Floodplain Administrator and/or his or her designee prior to issuance of flood permit.
    2. If Sec. 9.3.7.A.1. is satisfied, all proposed development shall comply with all applicable flood hazard reduction standards in Sec. 9.3.5.
    3. Provided they are not otherwise restricted activities per Sec. 9.3.7.A.1., the following structures and activities are allowed within drainage basin study and/or flood hazard soils-based floodway.
      1. General farming, pasture, outdoor plant or nurseries, horticulture, forestry, wildlife sanctuary, game preserves and other similar agricultural wildlife and related activities.
      2. Lawns, yards, gardens, parking areas, play areas and other similar uses.
      3. Golf courses, tennis courts, driving ranges, archery ranges, picnic grounds, parks, greenways, bikeways, hiking or horseback-riding trails, botanical gardens, open space and other similar private and public recreational activities.
      4. Any other activity not employing a structure and not subject to floating away during a flood.
      5. Any activity employing a structure, provided all portions of any structure, including foundation and supports, shall be located outside the floodway area and that any structure which overhangs the floodway is elevated above the depth of the 500-year flood.
    4. Legally permitted structures existing and lying within a drainage basin study and/or flood hazard soil-based floodway may be repaired, improved, strengthened and enlarged; provided that no construction is permitted which will:
      1. Enlarge the foundation area of the structure within the floodway;
      2. Increase the bulk of the building or structure within the floodway below the base flood; or
      3. Enlarge the surface area perpendicular to the direction of flow of the watercourse to which the floodway relates.
  2. Drainage Basin Study, Flood Study, and Flood Hazard Soils Floodway Fringe Standards
    The following provisions shall apply to those areas designated as floodway fringe based on drainage basin studies or flood hazard soils:
    1. New development within the drainage basin study and/or flood hazard soils-based floodway fringe must comply with Sec. 9.3.5., Sec. 11.4.6. and the following:
      1. When a structure is constructed on fill and the lowest floor is above the RFPE, the top of the fill shall be no lower than one (1) foot below the RFPE and shall extend in all directions at least fifteen (15) feet beyond the limits of the structure.
      2. Open storage materials subject to floating away during a flood must be placed on fill at least one (1) foot above the RFPE.
    2. The lot coverage of any lot may not exceed 50% of the portion of the drainage basin study and/or flood hazard soils-based floodway fringe on that lot, with the following exceptions:
      1. Any lot ½ acre or less in size which was recorded prior to May 2, 2006;
      2. Activities allowed in drainage basin study and flood hazard soils-based floodways as outlined in Sec. 9.3.7.A.3.; or
      3. Existing or approved structures, for which a building permit has been issued prior to July 19, 2022 shall be subject to the following:
        1. In the event of damage to such a structure which requires a substantial improvement of said structure, the structure may be repaired or rebuilt with one of the following administrative approvals:
          1. a) An administrative approval by the Floodplain Administrator and/or his or her designee if all the following are met:
            1. 1) The land use existing at the time of the flood or other casualty remains the same;
            2. 2) The use existing at the time of the flood or other casualty remains the same;
            3. 3) There is no rise in the BFE or, if there is any rise in the BFE, as determined by a flood study identifying upstream and downstream structures that will be impacted, it will:
              1. Not raise the levels of the base flood or future conditions flood onto impacted structures; and
              2. Not redirect velocities of water onto impacted structures.
          2. b) An administrative approval by the Floodplain Administrator and/or his or her designee for any redevelopment that does not increase the flood elevation and that decreases the bulk of an existing building or structure below the BFE by at least 25% of the portion exceeding 50% of the floodway fringe. Any additional fill or material being added as a part of the redevelopment shall be included for calculation of the bulk of the proposed redevelopment. A written request for an administrative approval shall be submitted to the Floodplain Administrator and/or his or her designee.
      4. Notwithstanding the preceding exceptions, a variance from the 50% lot coverage threshold in Sec. 9.3.7.B.2. may be sought by an applicant following the procedures prescribed in Sec.10.2.10.