In addition to the general development standards, the following standards shall be applicable in the flood fringe area.
(a) In areas designated on the flood maps as zone AE or AH.
(1) All new construction or substantial improvements of residential structures shall have the lowest floor, including basements, elevated to or above the base flood elevation.
(2) All new construction or substantial improvements of nonresidential structures shall have the lowest floor elevated to or above the base flood elevation; or together with attendant utility and sanitary facilities, be designed and constructed so that below the base flood elevation, the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy due to the base flood.
(3) Within zone AH, adequate drainage paths shall be provided around structures on slopes to guide floodwaters around and away from proposed structures.
(b) In areas of shallow flooding designated on the flood maps as zone AO.
(1) All new construction or substantial improvements of residential structures shall have the lowest floor, including basements, elevated above the highest adjacent grade at least as high as the depth number specified on the flood maps.
(2) All new construction or substantial improvements of nonresidential structures shall have the lowest floor elevated above the highest adjacent grade at least as high as the depth number specified on the flood maps; or together with attendant utility and sanitary facilities, be designed and constructed so that below that level, the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
(3) Adequate drainage paths shall be provided around structures on slopes to guide floodwaters around and away from proposed structures.
(c) All new construction or substantial improvements of structures with fully enclosed areas below the lowest floor (excluding basements) that are usable solely for parking of vehicles, building access or storage, 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 meet the following minimum criteria:
(1) For nonengineered openings:
(A) Have a minimum of two openings on different sides having a total net area of not less than 1 square inch for every square foot of enclosed area subject to flooding;
(B) The bottom of all openings shall be no higher than 1 foot above internal or external grade whichever is highest;
(C) Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided that they permit the automatic entry and exit of floodwaters; and
(D) Buildings with more than one enclosed area must have openings on exterior walls for each area to allow floodwater directly enter.
(2) Be certified by a licensed engineer or architect.
(d) A licensed professional architect or engineer shall develop or review the design, specifications, and plans and certify that the design and methods of construction are in accordance with accepted standards of practice for meeting the provisions of this chapter, and include the elevation to which such structures are floodproofed.
(e) New construction and substantial improvements of below-grade crawlspaces must be constructed in accordance with the requirements of FEMA Technical Bulletin 11-01 and amendments thereto. A licensed engineer or architect must certify that designs for below-grade crawlspaces meet these requirements.
(f) Accessory residential structures of less than 600 square feet that are used solely for parking or limited storage or both, and are constructed with the lowest floor below the base flood elevation, must be designed to meet the following minimum criteria.
(1) The structure must be anchored to resist flotation, collapse, and lateral movement;
(2) Any portion of the structure located below the base flood elevation must be constructed of flood-resistant materials;
(3) The structure must be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters in accordance with preceding subsection (c);
(4) All mechanical and utility equipment housed inside the structure must be elevated to or above the base flood elevation; and
(5) The use of the structure must be limited to parking or limited storage or both.
A licensed engineer or architect shall certify that designs for accessory residential structures subject to this subsection meet these minimum criteria.
(1990 Code, Ch. 21A, Art. 1, § 21A-1.8) (Added by Ord. 14-9; Am. Ord. 16-30)