Chapter 14.25
PROVISIONS FOR FLOOD HAZARD REDUCTION
Sections:
14.25.010 Standards of construction.
14.25.020 Standards for storage of materials and equipment.
14.25.030 Standards for utilities.
14.25.040 Additional development standards, including subdivisions.
14.25.050 Standards for manufactured homes.
14.25.060 Standards for recreational vehicles.
14.25.010 Standards of construction.
In all areas of special flood hazards the following standards are required:
A. Anchoring.
1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy; and
2. All manufactured homes shall meet the anchoring standards of TTC 14.25.050(B).
B. Construction Materials and Methods.
1. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage;
2. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage;
3. All new construction, substantial improvement and other proposed new development shall be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding; and
4. Within Zones AH or AO, adequate drainage paths shall be constructed around structures on slopes to guide floodwaters around and away from proposed structures.
C. Elevation and Floodproofing.
1. Residential Construction. Residential construction, new or substantial improvement, shall have the lowest floor, including basement:
a. In an AO Zone, elevated to or above the regulatory flood elevation, or elevated at least two feet above the highest adjacent grade if no depth number is specified.
b. In an A Zone where a BFE has not been determined, elevated to or above the regulatory flood elevation or be elevated in accordance with the criteria developed by the Director of the Arizona Department of Water Resources.
c. In Zones AE and AH, elevated to or above the regulatory flood elevation.
Upon completion of the structure, the elevation of the lowest floor including basement shall be certified by a registered professional surveyor, and verified by the community’s building inspector to be properly elevated. Such certification and verification shall be provided to the floodplain administrator.
2. Nonresidential Construction. Nonresidential construction, new or substantial improvement, shall have the lowest floor either elevated to conform with subsection (C)(1) of this section or together with attendant utility and sanitary facilities:
a. Be floodproofed below the elevation recommended under subsection (C)(1) of this section so that the structure is watertight with walls substantially impermeable to the passage of water;
b. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
c. Be certified by a registered professional engineer or architect that the standards of this section are satisfied. Such certification shall be provided to the floodplain administrator.
3. Flood Openings. All new construction and substantial improvement 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 floodwater. Designs for meeting this requirement must meet or exceed the following criteria:
a. Have a minimum of two openings, on different sides of each enclosed area, having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwater; or
b. Alternatively, a registered engineer or architect may design and certify the openings.
4. Manufactured Homes.
a. Manufactured homes shall meet the standards in TTC 14.25.050.
5. Garages and Accessory Structures.
a. Attached Garages.
i. A garage attached to a residential structure, constructed with the garage floor slab below the regulatory flood elevation, must be designed to allow for the automatic entry of flood waters. See subsection (C)(3) of this section. Areas of the garage below the regulatory flood elevation must be constructed with flood resistant materials. See subsection (B) of this section.
ii. A garage attached to a nonresidential structure must meet the above requirements or be dry floodproofed.
b. Detached Garages and Accessory Structures.
i. “Accessory structure” used solely for parking or limited storage may be constructed such that its floor is below the regulatory flood elevation, provided the structure is designed and constructed in accordance with the following requirements:
(A) Use of the accessory structure must be limited to parking or limited storage;
(B) The portions of the accessory structure located below the regulatory flood elevation must be built using flood-resistant materials;
(C) The accessory structure must be adequately anchored to prevent flotation, collapse and lateral movement;
(D) Any mechanical and utility equipment in the accessory structure must be elevated or floodproofed to or above the regulatory flood elevation;
(E) The accessory structure must comply with floodplain encroachment provisions in TTC 14.25.070; and
(F) The accessory structure must be designed to allow for the automatic entry and exit of flood waters in accordance with subsection (C)(3) of this section.
ii. Detached garages and accessory structures not meeting the above standards must be constructed in accordance with all applicable standards in this section. [Ord. 2015-02.]
14.25.020 Standards for storage of materials and equipment.
A. The storage or processing of materials that could be injurious to human, animal or plant life if released due to damage from flooding is prohibited in special flood hazard areas.
B. Storage of other material or equipment may be allowed if not subject to damage by floods and if firmly anchored to prevent flotation, or if readily removable from the area within the time available after flood warning. [Ord. 2015-02.]
14.25.030 Standards for utilities.
A. All new or replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system and discharge from systems into flood waters.
B. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
C. Waste disposal systems shall not be installed wholly or partially in a regulatory floodway. [Ord. 2015-02.]
14.25.040 Additional development standards, including subdivisions.
A. All new subdivision proposals and other proposed development (including proposals for manufactured home parks and subdivisions), greater than 50 lots or five acres, whichever is the lesser, shall:
1. Identify the area of the special flood hazard area and the elevation of the base flood.
2. Identify on the final plans the elevation(s) of the proposed structure(s) and pads. If the site is filled above the base flood elevation, the final lowest floor and grade elevations shall be certified by a registered professional engineer or surveyor and provided to the floodplain administrator.
B. All subdivision proposals and other proposed development shall be consistent with the need to minimize flood damage.
C. All subdivision proposals and other proposed development shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.
D. All subdivision proposals and other proposed development shall provide adequate drainage to reduce exposure to flood hazards. [Ord. 2015-02.]
14.25.050 Standards for manufactured homes.
All manufactured homes that are placed on site or substantially improved shall:
A. Be elevated so that the bottom of the structural frame or the lowest point of any attached appliances, whichever is lower, is at or above the regulatory flood elevation; and
B. Be securely anchored to an adequately anchored foundation system to resist flotation, collapse or lateral movement. Methods of anchoring may include, but are not to be 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. [Ord. 2015-02.]
14.25.060 Standards for recreational vehicles.
All recreational vehicles placed on site shall:
A. Be on site for fewer than 180 consecutive days;
B. Be fully licensed and ready for highway use. 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; or
C. Meet the permit requirements of Chapter 14.20 TTC and the elevation and anchoring requirements for manufactured homes in TTC 14.25.050. [Ord. 2015-02.]
14.25.070 Floodways.
Located within areas of special flood hazard established in TTC 14.15.020 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles and erosion potential, the following provisions apply:
A. Prohibit 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.
B. If this section is satisfied, all new construction and substantial improvements shall comply with all other applicable flood hazard reduction provisions of this chapter. [Ord. 2015-02.]