Danville Municipal Code Div. 4 Provisions for Flood Hazard Reduction

The standards set forth in this division are required in all areas of special flood hazards. (Ord. #133, §8-4831; Ord. #2002-02, §2)

a. 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.

b. All manufactured homes shall meet the anchoring standards of subsection 32-117.38.b. (Ord. #133, §8-4832; Ord. #2002-02, §2)

All new construction and substantial improvements shall be constructed:

a. With flood resistant materials as specified in FEMA Technical Bulletin TB 2-93, and utility equipment resistant to flood damage;

b. Using methods and practices that minimize flood damage;

c. 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. (Ord. #133, §8-4833; Ord. #2002-02, §2)

(See definitions for "basement," "lowest floor," "new construction," "substantial damage" and "substantial improvement").

a. Residential construction, new or substantial improvement shall have the lowest floor, including basement, elevated to or above one (1) foot above the base flood elevation. Base flood elevation shall be determined by one (1) of the methods in 32-117.23.b of this section.

b. Nonresidential construction shall either be elevated in conformance with subsection (a) or together with attendant utility and sanitary facilities:

1. Be floodproofed 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; and

3. Be certified by a registered professional engineer or architect that the standards of this subsection are satisfied. Such certifications shall be provided to the Development Services Director.

c. All new construction and substantial improvements 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 shall follow the guidelines in FEMA Technical Bulletins TB 10-93 and TB 7-93, and must exceed the following minimum criteria:

1. Have 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. The bottom of all openings shall be no higher than one (1) 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

2. Be certified by a registered professional engineer or architect.

d. Manufactured homes shall meet the standards in this section and also the standards in subsection 32-117.38.

e. Upon the completion of new structures or substantial improvements in Zone A, the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, and verified by the community building inspector to be properly elevated. Such certification and verification shall be provided to the Development Services Director. (Ord. #133, §8-4834; Ord. #2002-02, §2)

a. The storage or processing of materials that are in time of flooding buoyant, flammable, explosive, or could be injurious to human, animal or plant life is prohibited.

b. Storage of other material or equipment may be allowed if not subject to major damage by floods and firmly anchored to prevent flotation or if readily removable from the area within the time available after flood warning. (Ord. #133, §8-4835; Ord. #2002-02, §2)

a. All new and 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. (Ord. #133, §8-4836; Ord. #2002-02, §2)

a. All preliminary subdivision proposals shall identify the flood hazard area and the elevation of the base flood.

b. All final subdivision plans will provide the elevation of proposed structures and pads. If the site is filled above the base flood, the final pad elevation shall be certified by a registered professional engineer or surveyor and shall be provided to the Development Services Director.

c. All subdivision proposals shall be consistent with the need to minimize flood damage.

d. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage.

e. All subdivision proposals shall provide adequate drainage to reduce exposure to flood hazards. (Ord, #133, §8-4837; Ord. #2002-02, §2)

a. All new and substantially improved manufactured homes and additions to manufactured homes within Zone A on sites located:

• 1. Outside of a manufactured home park or subdivision;
• 2. In a new manufactured home park or subdivision;
• 3. In an expansion to an existing manufactured home park or subdivision; or

4. In an existing manufactured home park or subdivision on a site upon which a manufactured home has incurred "substantial damage" as the result of a flood shall be elevated so that the lowest floor is at or above one (1) foot above the base flood elevation and be securely anchored to a permanent foundation system to resist flotation, collapse or lateral movement.

b. All manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within Zones A1-30, AH, AE, V1-30, V, and VE on the community's Flood Insurance Rate Map that are not subject to the provisions above shall be securely fastened to an adequately anchored foundation system to resist flotation, collapse, and lateral movement, and be elevated so that either the:

1. Lowest floor of the manufactured home is at or above one (1) foot above the base flood elevation; or

2. The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than thirty-six (36) inches in height above grade.

c. Upon the completion of the structure, the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, and verified by the community building inspector to be properly elevated. Such certification and verification shall be provided to the Development Services Director. (Ord. #133, §8-4838; Ord. #2002-02, §2)

Areas designated as floodways are located within areas of special flood hazard established in subsection 32-117.12. Since the 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:

a. Encroachment, including fill, new construction, substantial improvements, and other development, is prohibited, unless certification by a registered professional engineer or architect is provided demonstrating that the encroachment shall not result in any increase in flood levels during the occurrence of the base flood discharge.

b. If paragraph a. is satisfied, all new construction, substantial improvements and other proposed new development shall comply with all applicable flood hazard reduction provisions of this division. (Ord. #133, §8-4839; Ord. #2002-02, §2)