§ 151.100 PROVISIONS FOR FLOOD HAZARD REDUCTION.
   (A)   General standards. In all flood prone areas, the following provisions are required.
      (1)   New construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure.
      (2)   Manufactured homes shall be elevated and anchored to prevent flotation, collapse or lateral movement. Method of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors. This standard shall be in addition to and consistent with applicable state requirements for resisting wind forces.
      (3)   New construction and substantial improvements be constructed with materials and utility equipment resistant to flood damage.
      (4)   New construction or substantial improvements shall be constructed by methods and practices that minimize flood damage.
      (5)   Electrical, heating, ventilation, plumbing, air conditioning equipment and other service facilities shall be designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
      (6)   New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood water into the systems.
      (7)   New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into systems and discharge from the systems into flood waters.
       (8)   On-site waste disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding.
      (9)   Any alteration, repair, reconstruction or improvements to a building which is in compliance with the provisions of this subchapter shall meet the requirements of new construction, as contained in this subchapter.
      (10)   Any alteration, repair, reconstruction or improvements to a building which is not in compliance with the provisions of this subchapter shall be undertaken only if the nonconformity is not extended.
   (B)   Specific standards. These provisions shall apply to all areas of special flood hazard as provided herein.
      (1)   In all areas of special flood hazard where base flood elevation data have been provided, including A Zones, Al-30, AE Zones, AO Zones, AH Zones and A99 Zones, and has provided a regulatory floodway, as set forth in § 151.093, the following provisions are required.
         (a)   Residential construction. New construction or substantial improvement to any residential building (or manufactured home) shall have the lowest floor, including basement, elevated no lower than one foot above the base flood elevation. Should solid foundation perimeter walls be used to elevate a structure, openings sufficient to facilitate the unimpeded movement of flood waters shall be provided in accordance with standards of subsection (B)(3).
         (b)   Nonresidential construction. New construction or substantial improvement of any commercial, industrial or nonresidential building shall have the lowest floor, including basement, elevated no lower than one foot above the level of the base flood elevation. Buildings located in all A Zones may be flood-proofed in lieu of being elevated, provided that all areas of the building below the required elevation are water tight with walls substantially impermeable to the passage of water and are built with structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. A registered professional engineer or architect shall certify that the standards of this subsection are satisfied. The certification shall be provided to the Development Director as set forth in § 151.099(B)(2).
         (c)   Elevated building. New construction or substantial improvements of elevated buildings that include fully enclosed areas formed by foundation and other exterior walls below the base flood elevation shall be designed to preclude finished living space and designed to allow for the entry and exit of flood waters to automatically equalize hydrostatic flood forces on exterior walls.
            1.   Designs for complying with this requirement must either be certified by a professional engineer or architect or meet the following minimum criteria:
               a.   Provide 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;
               b.   The bottom of all openings shall be no higher than one foot above grade; and
               c.   Openings may be equipped with screens, louvers, valves or other coverings or devices, provided they permit the automatic flow of floodwater in both directions;
            2.   Access to the enclosed area shall be the minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator); and
            3.   The interior portion of such enclosed area shall not be partitioned or finished into separate rooms in such a way as to impede the movement of floodwaters and all such petitions shall comply with the provisions of division (B) of this section.
         (d)   Standards for manufactured homes and recreational vehicles.
            1.   All manufactured homes placed or substantially improved, on individual lots or parcels, in expansions of existing manufactured home parks or subdivision or in substantially improved manufactured home parks or subdivisions must meet all the requirements of new construction, including elevations and anchoring.
            2.   All manufactured homes placed or substantially improved in an existing manufactured home park or subdivision must be elevated so that:
               a.   The lowest floor of the manufactured home is elevated no lower than one foot above the level of the base flood elevation on a permanent foundation;
               b.   All manufactured homes must be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement; and
               c.   In or outside of an existing or new manufactured home park or subdivision or in an expansion of an existing manufactured home park or subdivision, on which a manufactured home has incurred substantial damage as the result of a flood, any manufactured home placed or substantially improved must meet the standards of subsections a. and b. above.
         (e)   All recreational vehicles placed on site must either:
            1.   Be on the site for fewer than 180 consecutive days;
            2.   Be fully licensed and ready for highway use; or
            3.   The recreational vehicle must meet all the requirements for new construction, including anchoring and elevation requirements of subsection (B)(1)(d)1. or 2.a. and b.
      (2)   A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by a quick disconnect type utilities and security devices and has no permanently attached structures.
      (3)   In all areas of specific flood hazard where base flood elevation data or floodway data have not been provided, the provisions of § 151.099(C)(8) shall be utilized for all requirements relative to the base flood elevation or floodway.
   (C)   Standards for areas of special flood hazard zone A1-30 and AE with established base flood elevation but without floodways designated. Located within the areas of special flood hazard established in § 151.093, where streams existing with base flood data is provided but where no floodways have been provided (Zones A1-30 and AE), the following provisions apply.
      (1)   No encroachments, including fill material, new structures or substantial improvements shall be located within areas of special flood hazard, unless certification by a registered professional engineer is provided demonstrating that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the community. The engineering certification should be supported by technical data that conforms to standard hydraulic engineering principles.
      (2)   New construction or substantial improvements of buildings shall be elevated or flood- proofed to elevations established in accordance with division (B) of this section.
   (D)   Standards for areas of shallow flooding (AO and AH Zones). Located within the areas of special flood hazard established in § 151.093 are areas designated as shallow flooding areas. These areas have special flood hazards associated with base flood depths of one to three feet where a clearly defined channel does not exist and where the path of flooding is unpredictable and indeterminate; therefore, the following provisions apply.
      (1)   All new construction and substantial improvements of residential buildings shall have the lowest floor, including basement, elevated to the depth number specified on the Flood Insurance Rate Map, in feet, above the highest adjacent grade. If no depth number is specified, the lowest floor, including basement, shall be elevated, at least two feet above the highest adjacent grade.
      (2)   All new construction and substantial improvements of non-residential buildings shall:
         (a)   Have the lowest floor, including basement, elevated to the depth number specified on the Flood Insurance Rate Map, in feet, above the highest adjacent grade. If no depth number is specified, the lowest floor, including basement, shall be elevated at least two feet above the highest adjacent grade; or
         (b)   Together with attendant utility and sanitary facilities be completely flood-proofed to or above that level so that any space below that level 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 slopes to guide floodwaters around and away from proposed structures.
   (E)   Standards for areas protected by flood protection systems (A-99 Zones). Located within the areas of special flood hazard established in § 151.093 are areas of the 100-year flood protected by a flood protection system which is under construction but where base flood elevations and flood hazard factors have not been determined. With these areas (A-99 Zones), the following provisions apply: all provisions of § 151.099 and divisions (A) and (H) of this section shall apply.
   (F)   Standards for areas of special flood hazard with established base flood elevation and with floodway designated. Located within the areas of special flood hazard established in § 151.093, where streams exist with base flood data and floodways provided, the following provisions apply.
      (1)   No encroachments, including fill material, new construction, substantial improvements or other development shall be located within designated floodways, unless certification from a registered professional engineer is provided demonstrating that the cumulative effect of the proposed encroachments or new development will not increase the water surface elevation of the base flood during the occurrence of the base flood discharge at any point within the community. The engineering certification should be supported by technical data that conforms to standard hydraulic engineering principles.
      (2)   If subsection (F)(1) above is satisfied, new construction or substantial improvements of buildings shall be elevated or flood-proofed to elevations established in accordance with division (B) of this section.
   (G)   Standard for unmapped streams. Located in Collierville, Tennessee are unmapped streams where areas of special flood hazard are neither indicated nor base flood data or floodways have been provided. Adjacent to such streams the following provisions shall apply:
      (1)   In areas adjacent to such unmapped streams, no encroachments, including fill material or structures shall be located within an area of at least equal to twice the width of the stream along each side of the stream, unless certification by a registered professional engineer is provided demonstrating that the cumulative effect of the proposed development, when combined with all existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the locality;
      (2)   When flood elevation data is available, new construction or substantial improvements of buildings shall be elevated or flood-proofed to elevations established with § 151.099(B)(2).
   (H)   Standards for subdivision proposals. Subdivision proposals and other proposed new development, including manufactured home parks or subdivision, shall be reviewed to determine whether such proposals will be reasonably safe from flooding. If a subdivision proposal or other proposed new development is in a flood-prone area, any such proposals shall be reviewed to ensure that:
      (1)   All subdivision proposals shall be consistent with the need to minimize flood damage;
      (2)   All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize or eliminate flood damage;
      (3)   All subdivision proposals shall have adequate drainage provided to reduce exposure to flood hazards;
      (4)   Base flood elevation data shall be provided for subdivision proposals and other proposed development (including manufactured home parks and subdivisions) which is greater than 50 lots and/or five acres.
(`00 Code, § 11-705)