Chapter 68.50
Provisions for Flood Hazard Reduction

Sections:

68.50.010    Standards of construction.

68.50.020    Standards for utilities.

68.50.030    Standards for subdivisions.

68.50.040    Standards for manufactured homes.

68.50.050    Standards for recreational vehicles.

68.50.060    Coastal high hazard areas.

68.50.070    Flood-related erosion-prone areas.

68.50.010 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 adequately anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.

2. All manufactured homes shall meet the anchoring standards of CMC 68.50.040.

B. Construction Materials and Methods. All new construction and substantial improvement shall be constructed:

1. With materials and utility equipment resistant to flood damage below the base flood elevation;

2. Using methods and practices that minimize flood damage; and

3. 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.

C. Elevation and Floodproofing. (See Chapter 68.20 CMC definitions for “basement,” “lowest floor,” “new construction,” “substantial damage” and “substantial improvement.”)

1. Residential construction, new or substantial improvement, shall have the lowest floor, including basement:

a. In an A Zone, elevated to at least one foot above the base flood elevation.

b. In all other zones, elevated to 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.

2. Nonresidential construction, new or substantial improvement, shall either be 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 subsection are satisfied. Such certification shall be provided to the Floodplain Administrator.

3. 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:

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

b. 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.

4. Manufactured homes shall also meet the standards in CMC 68.50.040.

5. Garages and low-cost accessory structures shall meet the following standards:

a. Attached Garages.

i. A garage attached to a residential structure, constructed with the garage floor slab below the base flood elevation, must be designed to allow for the automatic entry of floodwaters. Areas of the garage below the base flood elevation must be constructed with flood resistant materials.

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 structures” used solely for parking (two-car detached garages or smaller) or limited storage (small, low-cost sheds), may be constructed such that its floor is below the base 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 base 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 a minimum of one foot above the base flood elevation; and

(E) The accessory structure must be designed to allow for the automatic entry of floodwaters in accordance with subsection (C)(3) of this section. (Ord. 2095 § 3 (Exh. A), 2019; Ord. 1956 § 9, 2004)

68.50.020 Standards for utilities.

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

1. Infiltration of flood waters into the systems; and

2. Discharge from the 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. 2095 § 3 (Exh. A), 2019)

68.50.030 Standards for subdivisions.

A. All preliminary subdivision proposals, including proposals for manufactured home parks and subdivisions, greater than 50 lots or five acres, whichever is the lesser, shall identify the special flood hazard area and the elevation of the base flood.

B. 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 civil engineer or land surveyor and provided as part of an application for a Letter of Map Revision based on Fill (LOMR-F) to the Floodplain Administrator.

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 subdivisions shall provide adequate drainage to reduce exposure to flood hazards. (Ord. 2095 § 3 (Exh. A), 2019)

68.50.040 Standards for manufactured homes.

A. All manufactured homes that are placed or substantially improved within Zones A1-30, AH, and AE on the community’s Flood Insurance Rate Map 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 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.

B. All manufactured homes that are placed or substantially improved on sites located within Zones V1-30, V, and VE on the community’s Flood Insurance Rate Map will meet the requirements of subsection A of this section and CMC 68.50.060.

C. 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 of subsection A of this section will be securely fastened to an adequately anchored foundation system to resist flotation collapse and lateral movement, and elevated so that either the:

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

2. 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 is securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement. (Ord. 2095 § 3 (Exh. A), 2019)

68.50.050 Standards for recreational vehicles.

A. All recreational vehicles placed on sites within Zones A1-30, AH, and AE on the community’s Flood Insurance Rate Map will either:

1. Be on the site for fewer than 180 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

2. Meet the permit requirements of Chapter 68.40 CMC and the elevation and anchoring requirements for manufactured homes in CMC 68.50.040(A).

B. Recreation vehicles placed on sites within Zones V1-30, V, and VE on the community’s Flood Insurance Rate Map will meet the requirements of subsection A of this section and CMC 68.50.060. (Ord. 2095 § 3 (Exh. A), 2019)

68.50.060 Coastal high hazard areas.

Within coastal high hazard areas as established under CMC 68.30.020, the following standards shall apply:

A. All new construction and substantial improvement shall be elevated on adequately anchored pilings or columns and securely anchored to such pilings or columns so that the lowest horizontal portion of the structural members of the lowest floor (excluding the pilings or columns) is elevated to or above the base flood level. The pile or column foundation and structure attached thereto is anchored to resist flotation, collapse, and lateral movement due to the effects of wind and water loads acting simultaneously on all building components. Water loading values used shall be those associated with the base flood. Wind loading values used shall be those required by applicable State or local building standards.

B. All new construction and other development shall be located on the landward side of the reach of mean high tide.

C. All new construction and substantial improvement shall have the space below the lowest floor free of obstructions or constructed with breakaway walls as defined in Chapter 68.20 CMC. Such enclosed space shall not be used for human habitation and will be usable solely for parking of vehicles, building access or storage.

D. Fill shall not be used for structural support of buildings.

E. Manmade alteration of sand dunes which would increase potential flood damage is prohibited.

F. The Floodplain Administrator shall obtain and maintain the following records:

1. Certification by a registered engineer or architect that a proposed structure complies with subsection A of this section.

2. The elevation (in relation to mean sea level) of the bottom of the lowest structural member of the lowest floor (excluding pilings or columns) of all new and substantially improved structures, and whether such structures contain a basement. (Ord. 2095 § 3 (Exh. A), 2019)

68.50.070 Flood-related erosion-prone areas.

A. The Floodplain Administrator shall require permits for proposed construction and other development within all flood-related erosion-prone areas as known to the community.

B. Permit applications shall be reviewed to determine whether the proposed site alterations and improvements will be reasonably safe from flood-related erosion and will not cause flood-related erosion hazards or otherwise aggravate the existing hazard.

C. If a proposed improvement is found to be in the path of flood-related erosion or would increase the erosion hazard, such improvement shall be relocated or adequate protective measures shall be taken to avoid aggravating the existing erosion hazard.

D. Within Zone E on the Flood Insurance Rate Map, a setback is required for all new development from the ocean or bay to create a safety buffer consisting of a natural vegetative or contour strip. This buffer shall be designated according to the flood-related erosion hazard and erosion rate, in relation to the anticipated “useful life” of structures, and depending upon the geologic, hydrologic, topographic, and climatic characteristics of the land. The buffer may be used for suitable open space purposes, such as for agricultural, forestry, outdoor recreation and wildlife habitat areas, and for other activities using temporary and portable structures only. (Ord. 2095 § 3 (Exh. A), 2019)