(A) Residential construction. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated 24 inches above the base flood elevation as per FEMA and Brazoria County Floodplain Management. A registered professional engineer, architect or land surveyor shall submit an elevation certification to the Floodplain Administrator that the standard of this section, as proposed in § 153.41(A)(2)(a), is satisfied prior to construction showing base floor elevations with proposed final elevations. A final elevation certificate, verifying final elevation is 24 inches above the base floor elevation, is required to be submitted upon completion of the structure. Construction in special flood hazard areas must present a drainage study completed by a registered professional engineer or surveyor showing no adverse impact of impervious runoff in surrounding areas and properties. Submittal of drainage mitigation will be required along with the drainage study to combat adverse effects.
(B) Non-residential construction.
(1) New construction and substantial improvements of any commercial, industrial or other non-residential structure shall either have the lowest floor, including basement, elevated 24 inches above the base flood level as per FEMA and Brazoria County Floodplain Administration or, together with attendant utility and sanitary facilities, be designed 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 the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. A registered professional engineer or architect shall develop and/or review structural design, specifications and plans for the construction, and shall certify that the design and methods of constriction are in accordance with accepted standards of practice, as outlined herein. All new commercial construction and substantial improvements to include industrial or other non-residential structures and/or civil work regardless of special flood zone, must submit a drainage study to include runoff calculations showing no adverse effects of impervious runoff and drainage mitigation to be reviewed by the City Engineer. A record of the certification which includes the specific elevation, in relation to mean sea level, to which the structures are floodproofed shall be maintained by the Floodplain Administrator.
(2) A registered professional engineer, architect or land surveyor shall submit an elevation certification to the Floodplain Administrator that the standard of this section, as proposed in § 153.41(A)(2)(a), is satisfied prior to construction showing base floor elevations with proposed final elevations. A final elevation certificate, verifying final elevation is 24 inches above the base floor elevation, is required to be submitted upon completion of the structure.
(C) Enclosures. New construction and substantial improvements, with fully enclosed areas below the lowest floor that are usable 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 flood waters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:
(1) A minimum of two openings on separate walls 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.
(2) The bottom of all openings shall be no higher than one foot above grade.
(3) Openings may be equipped with screens, louvers, valves or other coverings or devices provided that they permit the automatic entry and exit of flood waters.
(D) Manufactured homes.
(1) Require that all manufactured homes to be placed within Zone A on a community's FHBM or FIRM, shall be installed using methods and practices which minimize flood damage. For the purpose of this requirement, manufactured homes must be elevated 24 inches above base floor elevation, as per FEMA and Brazoria County Floodplain Administration, and anchored to resist flotation, collapse or lateral movement. Methods of anchoring may include, but are not limited to use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.
(2) Require that manufactured homes that are placed or substantially improved within Zones A1-30, AH and AE on the community's FIRM on-sites:
(a) Outside of a manufactured home park or subdivision;
(b) In a new manufactured home park or subdivision;
(c) In an expansion to an existing manufactured home park or subdivision; or
(d) In an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as a result of a flood, be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated 24 inches above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
(3) Require that manufactured homes be placed, or substantially improved, on sites in an existing manufactured home park or subdivision with Zones A1-30, AH and AE on the community's FIRM that are not subject to the provisions of this division (D), be elevated so that either:
(a) The lowest floor of the manufactured home 24 inches above the base flood elevation;
or
(b) The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade, and be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
(E) Recreational vehicles. Require that recreational vehicles placed on sites within Zones A1-30, AH and AE on the community's FIRM either:
(1) Be on the site for fewer than 180 consecutive days;
(2) Be fully licensed and ready for highway use; or
(3) Meet the permit requirements of § 153.41(A)(1), and the elevation and anchoring requirements for manufactured homes in division (D) above. A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices and has no permanently attached additions.
(Ord. 102-87, passed 3-17-87; Am. Ord. 102-89, passed 1-17-89; Am. Ord. 104-89, passed 2-21-89; Am. Ord. 104-08, passed 12-18-07; Am. Ord. 107-22, passed 4-19-22)