Hallsville Specific Standards ordinance (§ 410.150)

A. In all areas of special flood hazard, once base flood elevation data is obtained, as set forth in Article IV, Section 410.140(B), the following provisions are required:

1. Residential Construction. New construction or substantial improvement of any residential structure, including manufactured homes, shall have the lowest floor, including basement, elevated to at least one (1) foot above base flood level.

2. Non-Residential Construction. New construction or substantial improvement of any commercial, industrial, or other non-residential structure, including manufactured homes, shall have the lowest floor, including basement, elevated to or one (1) foot above the base flood level or, together with attendant utility and sanitary facilities, be floodproofed so that below the base flood level, the structure is watertight with walls substantially impermeable to the passage of water and with structural components having a capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. A registered professional engineer or architect shall certify that the standards of this subsection are satisfied. Such certification shall be provided to the Floodplain Administrator as set forth in Article III, Section 410.120(G)(3).

3. Require, for all new construction and substantial improvements, that fully enclosed areas below lowest floor used solely for parking of vehicles, building access, or storage in an area other than a basement and that are subject to flooding may 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 either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:

a. A minimum of two (2) openings having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding shall be provided; and

b. The bottom of all openings shall be no higher than one (1) foot above grade.

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.

B. In all areas of special flood hazard, once floodway data is obtained, as set forth in Article IV, Section 410.140(B), the following provisions are required:

1. The designated floodway shall be based on the standard that the area chosen for the floodway must be designed to carry the waters of the base flood, without increasing the water surface elevation more than one (1) foot at any point; and

2. The community shall prohibit any encroachments, including fill, new construction, substantial improvements, and other development with the designated regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the base flood discharge.