Sec. 39.05. - Provisions for flood hazard reduction.

(a)

Standards of construction. In all areas of special flood hazards the following standards are required:

1. Anchoring.

a.

All new construction and substantial improvements shall be adequately 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 Section 39.05(d).

2.

Construction materials and methods. All new construction and substantial improvement shall be constructed:

a.

With materials 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; and if

d.

Within zones AH or AO, so that there are adequate drainage paths around structures on slopes to guide flood waters around and away from proposed structures.

3.

Elevation and floodproofing. (See section 39.02 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:

i.

In an AO zone, elevated above the highest adjacent grade to a height exceeding the depth number specified in feet on the FIRM by at least one foot, or elevated at least three feet above the highest adjacent grade if no depth number is specified.

ii.

In an A zone, elevated at least one foot above the base flood elevation, as determined by the City of Colusa.

iii.

In all other zones, elevated at least one foot above the base flood elevation.

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 floodplain administrator.

b.

Nonresidential construction, new or substantial improvement, shall either be elevated to conform with section 39.05(a)(3)(a) above, or together with attendant utility and sanitary facilities:

i.

Be floodproofed below the elevation specified in section 39.05(a)(3)(a) so that the structure is watertight with walls substantially impermeable to the passage of water.

ii.

Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.

iii.

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.

c.

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 exceed the following minimum criteria:

i.

Be certified by a registered professional engineer or architect to comply with the guidelines for engineered openings in FEMA Technical Bulletin 1, or

ii.

Have 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. 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.

d.

Manufactured homes shall also meet the standards in section 39.05(d).

(b)

Standards for utilities.

1.

All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate:

a.

Infiltration of flood waters into the systems.

b.

Discharge from the systems into flood waters.

2.

On-site waste disposal systems shall be located to avoid impairment to them, or contamination from them during flooding.

(c)

Standards for subdivisions.

1.

All preliminary subdivision proposals shall identify special flood hazard areas and the elevation of the base flood.

2.

All subdivision plans will provide the elevation of proposed structure(s) and pad(s). If the site is filled above the base flood elevation, the lowest floor and pad elevations shall be certified by a registered professional engineer or surveyor and provided to the floodplain administrator.

3.

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

4.

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

All subdivisions shall provide adequate drainage to reduce exposure to flood hazards.

(d)

Standards for manufactured homes.

All manufactured homes that are placed or substantially improved, within Zones AI-30, AH, and AE on the community's flood insurance rate map, shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to at least one foot above the base flood elevation and be securely fastened to an adequately anchored foundation system to resist flotation collapse and lateral movement.

(e)

Standards for recreational vehicles.

1.

All recreational vehicles placed on sites within Zones A1-30, AH, and AE on the community's flood insurance rate map will either:

a.

Be on the site for fewer than one hundred eighty consecutive days, and 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

b.

Meet the permit requirements of this ordinance and the elevation and anchoring requirements for manufactured homes in section 39.05(d).

(f)

Floodways. Located within areas of special flood hazard established in Section 39.03(b) are areas designated as floodways. 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.

1.

Prohibit encroachments, including fill, new construction, substantial improvement, and other new development unless certification by a registered professional engineer or architect is provided demonstrating that encroachments shall not result in any increase in [the base] flood elevation during the occurrence of the base flood discharge.

2.

If Section 39.05(f)(1) is satisfied, all new construction, substantial improvement, and other proposed new development shall comply with all other applicable flood hazard reduction provisions othis ordinance.

(Ord. No. 563, § 1, 2, 12-19-2023)