In all areas of special flood hazards where base flood elevation data have been provided as set forth in § 154.02(E) or § 154.06(C), the following provisions are required:
   (A)   Residential construction.  New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to or above the base flood elevation.
   (B)   Nonresidential construction.  New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated to the level of the base flood elevation; or, together with attendant utility and sanitary facilities, shall:
      (1)   Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water;
      (2)   Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
      (3)   Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting the standards of this section.
   (C)   Accessory structures.  An exemption to the elevation or dry floodproofing standards may be granted by the city for accessory structures (e.g., sheds, detached garages) containing 576 square feet or less in gross floor area.  Such structures must meet the encroachment provisions of division (D)(1) of this section and the following additional standards:
      (1)   They shall not be used for human habitation;
      (2)   They shall be designed to have low flood damage potential;
      (3)   They shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of flood waters;
      (4)   They shall be firmly anchored to prevent flotation; and
      (5)   Service facilities, such as electrical and heating equipment, shall be elevated or floodproofed.
   (D)   Floodways; areas with floodways.  The Floodway Insurance Study referenced in § 154.02(E) identifies a segment within areas of special flood hazard known as a floodway.  Floodways may also be delineated in other sources of flood information as specified in § 154.06(C).  The floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles, and erosion potential.  The following provisions apply within all delineated floodway areas.
      (1)   Prohibit encroachments, including fill, new construction, substantial improvements, and other development unless a hydrologic and hydraulic analysis performed in accordance with standard engineering practices demonstrates that the proposed encroachment would not result in any increase in flood levels during the occurrence of the base flood discharge.
      (2)   If division (D)(1) of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section.
      (3)   Any encroachment within the floodway that would result in an increase in base flood elevations can only be granted upon the prior approval by the Federal Emergency Management Agency.  Such requests must be submitted by the City Manager to the Federal Emergency Management Agency and must meet the requirements of the National Flood Insurance Program.
   (E)   Enclosures below the lowest floor.  The following standards apply to all new and substantially improved residential and nonresidential structures which are elevated to the base flood elevation using pilings, columns, or posts.  Fully enclosed areas below the lowest floor that are useable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters.  Designs for meeting this requirement must:
      (1)   Be certified by a registered professional engineer or architect; or
      (2)   Must meet or exceed the following criteria:
         (a)   A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided.
         (b)   The bottom of all openings shall be no higher than one foot above grade.  Openings may be equipped with screens, louvers, or other openings provided that they permit the automatic entry and exit of floodwaters.
      (3)   Any enclosure which meets these criteria shall be considered as having met the requirements of § 154.04(A).
(Ord. 5-2006, passed 4-5-06)