(1) General Standards. In all areas of special flood hazards, compliance with the following standards is required:
1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure;
2. All manufactured homes shall likewise be anchored to prevent flotation, collapse or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors (reference FEMA’s "Manufactured Home Installation in Flood Hazard Areas" guidebook for additional techniques).
(b) Construction Materials and Methods. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage, using methods and practices that minimize flood damage. Electrical, heating, ventilation, plumbing, and air-conditioning equipment and other service facilities shall be designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
1. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system;
2. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharge from the systems into flood waters; and,
3. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
(d) Subdivision Proposals.
1. All subdivision proposals shall:
a. Be consistent with the need to minimize flood damage;
b. Have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage; and
c. Have adequate drainage provided to reduce exposure to flood damage; and
2. Where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated for subdivision proposals and other proposed developments which contain at least 50 lots or five acres (whichever is less).
(e) Review of Development Permits. Where elevation data is not available either through the Flood Insurance Study or from another authoritative source, applications for development permits shall be reviewed to assure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. Failure to elevate at least two feet above grade in these zones may result in higher insurance rates.
(f) Recreational Vehicles. Recreational vehicles placed on sites will either:
1. Be on the site for fewer than 180 consecutive days, or
2. Be fully licensed and ready for highway use, on its wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions.
(2) Specific Standards. In all areas of special flood hazards where base flood elevation data has been provided as required in subsections 9.6707(1) or (2), the following provisions are required:
(a) Residential Construction.
1. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to a minimum of one foot above the base flood elevation.
2. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or 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 either be certified by a registered professional engineer or architect or must meet or exceed the following minimum 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.
c. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
(b) Nonresidential Construction. New construction and substantial improvement of any commercial, employment and 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 flood proofed 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;
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 provisions of this subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the building official as required in section 9.6707.
4. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subparagraph (2)(a)2. of this section.
5. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g. a building constructed to the base flood level will be rated as one foot below that level).
(c) Manufactured Homes. All manufactured homes to be placed or substantially improved within Zones A1-30, AH, and AE shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at or above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of subsection (1)(a)(2) of this section.
(d) Floodways. Within areas of special flood hazard established in section 9.6706 are areas designated as floodways. Since a 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:
1. Prohibition on encroachments, including fill, new construction, substantial improvements, and other development unless certification by a registered professional engineer or architect is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge; and
2. If the conditions of subparagraph 1. above are met, all new construction and substantial improvements shall comply with all other applicable flood hazard reduction provisions of this section.
(e) Shallow Flooding Areas – With Depth Designations. Shallow flooding zones appear on Flood Insurance Rate Maps (FIRM), with depth designations, wherever such flooding occurs on sloping water surfaces such as alluvial fan flow, wave wash after the wave has broken, etc. In these areas, the following provisions apply:
1. New construction and substantial improvements of residential structures within these zones shall have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, to at least one foot above the depth number specified on the FIRM. Where appropriate, such structures shall be elevated above the crown of the nearest road, to at least one foot above the depth number specified in the FIRM. Where hazardous velocities are noted on the FIRM, consideration shall be given to mitigating the effects of these velocities through proper construction techniques and methods.
2. New construction and substantial improvements of nonresidential structures within these zones shall either:
a. Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site to at least one foot above the depth number specified on the FIRM; or
b. Together with attendant utility and sanitary facilities, be completely floodproofed to at least one foot 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. If this method is used, compliance shall be certified by a registered professional engineer or architect.
c. Adequate drainage paths shall be provided around structures on slopes to guide floodwaters around and away from proposed structures.
Where hazardous velocities are noted on the FIRM, consideration shall be given to mitigating the effects of these velocities through proper construction techniques and methods.