Ventura Municipal Code Ch. 12.430 Floodplain Development Standards

The floodplain development standards set forth in this chapter apply to the construction of any new structure, any substantial improvement of an existing structure, and/or any other development occurring in a special flood hazard area located in the city. Such standards shall apply in addition to any applicable floodplain regulations or restrictions adopted by this code. (Ord. No. 2021-001, § 1, 1-11-21)

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

1. With flood-resistant materials as specified in the most current FEMA Technical Bulletin, and utility equipment resistant to flood damage;

2. Using methods and practices that minimize flood damage;

3. With electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or located at a minimum of two feet above base flood elevation so as to prevent water from entering or accumulating within the components during conditions of flooding; and

4. Within all zone A special flood hazard areas, so that there are adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures.

C. Elevation and Floodproofing. Residential and nonresidential structures shall be floodproofed as follows:

1. Residential Construction. All new or substantial improvement of a residential structure shall have the lowest floor, including basement:

a. In A, AE, and AH zones, elevated above the highest adjacent grade to a height equal to or exceeding the depth number specified in feet on the FIRM, or elevated at least two feet above the highest adjacent grade if no depth number is specified;

b. In AO zones without velocity, elevated above the highest adjacent grade to a height exceeding the depth number specified in feet on the FIRM by at least two feet, or elevated at least four feet above the highest adjacent grade if no depth number is specified;

c. In all other zones, elevated at least two feet above the base flood elevation as determined in the manner provided for provided for in Chapter 12.440.

d. New development proposals will be designed, to the maximum extent practicable, so residential building sites, sidewalks, driveways, and roadways are located on land with a natural grade with elevation not less than the base flood elevation and with evacuation routes leading directly out of the floodplain area.

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 floodplain administrator to be properly elevated.

2. Nonresidential Construction. All new construction or substantial improvement of a nonresidential structure shall either be elevated to conform with subsection (C)(1) of this section or, together with any attendant utility and sanitary facilities:

a. Be floodproofed below the elevation required by 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, and such certification provided to the floodplain administrator.

New development proposals will be designed, to the maximum extent practicable, so nonresidential building sites, sidewalks, driveways, parking lots, and access/egress roads are located on land with a natural grade with elevation not less than the base flood elevation and with evacuation routes leading directly out of the floodplain area.

3. Parking, Building Access or Storage Areas. All new construction and substantial improvement with fully enclosed areas below the lowest floor (excluding basement) 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 the most current FEMA Technical Bulletins, and must exceed the following minimum criteria:

a. Such areas shall be constructed with 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 the openings shall be no higher than one foot above grade; but the openings may be equipped with screens, louvers, valves or other coverings or devices; provided, that they permit the automatic entry and exit of floodwater. The calculation for the screening area shall only use the net area or “blow through” opening for vent area calculations rather than the rough dimensions of the openings; or

b. Be designed and certified by a registered professional engineer or architect.

4. Garages and Low-Cost Accessory Structures.

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 and exit 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. For guidance on below grade parking areas, see the current FEMA Technical Bulletin.

b. Detached Garages and Accessory Structures. “Accessory structures” used solely for parking (two-car detached garages or smaller) or limited storage (small, low-cost sheds) may be constructed such that their floor is below the base flood elevation, provided the structure is designed and constructed in accordance with the following requirements:

i. Use of the accessory structure must be limited to parking or limited storage;

ii. The portions of the accessory structure located below the base flood elevation must be built using flood-resistant materials;

iii. The accessory structure must be adequately anchored to prevent flotation, collapse and lateral movement;

iv. Any mechanical and utility equipment in the accessory structure must be floodproofed or elevated two feet above the base flood elevation;

v. The accessory structure must comply with floodplain encroachment provisions in Section 12.430.070; and

vi. The accessory structure must be designed to allow for the automatic entry and exit of floodwaters in accordance with this section.

5. Critical Facilities.

a. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters.

b. Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities to the extent possible. (Ord. No. 2021-001, § 1, 1-11-21)

A. All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and to also eliminate discharge from the system into floodwaters.

B. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. (Ord. No. 2021-001, § 1, 1-11-21)

A. All preliminary subdivision proposals shall provide hydrologic and hydraulic engineering analysis to identify all floodwater drainage flows into and through the project area as well as the 100-year, 500-year, and floodway flood elevations and boundaries.

1. Analysis shall use the city’s most recent LiDAR topography.

2. Analysis shall be consistent with the most current FEMA, United States Army Corps of Engineers, Ventura County watershed protection district, and city drainage studies and models.

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, the pad elevation(s), and the lowest adjacent grade shall be certified by a registered professional engineer or surveyor and provided 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.

F. In areas upstream of the limit of study, as delineated on the community FIRM, where base flood elevation data is not available, a floodplain study must be performed by a professional engineer (PE) establishing the base flood elevation and the floodplain and floodway boundaries.

G. All subdivision developments will be designed so residential building sites, sidewalks, driveways, and roadways are located on land with a natural grade with elevation not less than the base flood elevation. (Ord. No. 2021-001, § 1, 1-11-21)

A. All manufactured homes that meet one of the four categories in this subsection are placed or substantially improved within special flood hazard areas identified as A zones on the flood insurance rate map and meet the criteria hereinafter set forth in this subsection shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated at least two feet above the base flood elevation, and shall be securely fastened to an adequately anchored foundation system to resist flotation, collapse, and lateral movement:

1. The manufactured home is outside of a manufactured home park or subdivision;

2. The manufactured home is a new manufactured home park or subdivision;

3. The manufactured home is located in an expansion to an existing manufactured home park or subdivision; or

4. The manufactured home is located 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.

B. All manufactured homes that are placed or substantially improved on sites located within special flood hazard areas identified as V zones on the flood insurance rate map shall meet the requirements of subsection A of this section and Section 12.430.080.

C. All manufactured homes that are placed or substantially improved on sites in an existing manufactured home park or subdivision within all zone A and zone V special flood hazard areas on the flood insurance rate map and that are not subject to the provisions of subsection A of this section shall be securely fastened to an adequately anchored foundation system to resist flotation, collapse, and lateral movement, and be elevated so that either:

1. The lowest floor of the manufactured home is at least two feet 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 36 inches in height above grade.

D. Upon installation of a manufactured home, the elevation of the lowest floor, including any basement, shall be certified by a registered professional engineer or surveyor and verified by the floodplain administrator to be properly elevated. Such certification and verification shall be provided to the floodplain administrator. (Ord. No. 2021-001, § 1, 1-11-21)

A. All recreational vehicles placed on sites within zones A1 through 30, AH, and AF on the flood insurance rate map shall 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 12.440, and the elevation and anchoring requirements for manufactured homes in Section 12.430.050(A).

B. Recreation vehicles placed on sites within zones V1 through 30, V, and VE on the flood insurance rate map will meet the requirements of subsection A of this section and Section 12.430.080. (Ord. No. 2021-001, § 1, 1-11-21)

The following standards apply to new construction, substantial improvement or other development in a floodway:

A. Until a floodway is adopted or mapped within a FIRM, no new construction, substantial development, or other development (including fill) shall be permitted within a zone A special flood hazard zone area unless it is demonstrated through a hydrologic and hydraulic engineering analysis to demonstrate that the cumulative effect of the proposed development, when combined with all other development, will not increase the water surface elevation of the base flood more than one foot at any point.

B. Encroachments, including fill, new construction, substantial improvement, and other new development is prohibited within a floodway unless certification by a registered professional engineer is provided demonstrating that the encroachments will not result in any increase in the base flood elevation during the occurrence of the base flood discharge.

C. If the requirement of subsection B of this section is satisfied, all new construction, substantial improvement, and other proposed new development shall comply with all other applicable flood hazard reduction provisions of this chapter. (Ord. No. 2021-001, § 1, 1-11-21)

The following standards apply to new construction, substantial improvement or other development within coastal high hazard areas:

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 shall be 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 the 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, and shall be usable solely for parking of vehicles, building access or storage. Where breakaway walls are used, they shall have a safe design loading resistance of not less than 10 and no more than 20 pounds per square foot. Use of breakaway walls must be certified by a registered engineer or architect and shall meet the following conditions:

1. Breakaway wall collapse shall result from a water load less than that which would occur during the base flood; and

2. The elevated portion of the building shall not incur any structural damage due to the effects of wind and water loads acting simultaneously in the event of the base flood.

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

E. Human-made 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; and

2. The elevation (in relation to mean sea level) of the bottom of the lowest horizontal 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. No. 2021-001, § 1, 1-11-21)