23.33.050 PROVISIONS FOR FLOOD HAZARD REDUCTION.
(a) Standards of Construction. In all areas of special flood hazards the following standards are required:
(i) 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.
(ii) All manufactured homes shall meet the anchoring standards of subsection (e).
(2) Construction Materials and Methods. All new construction and substantial improvements of structures, including manufactured homes, shall be constructed:
(i) With flood resistant materials, and utility equipment resistant to flood damage for areas below the base flood elevation;
(ii) Using methods and practices that minimize flood damage;
(iii) 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
(iv) 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 23.33.020, Definitions, for "basement," "lowest floor," "new construction," "substantial damage" and "substantial improvement.")
(i) Residential Construction. All new construction or substantial improvements of residential structures shall have the lowest floor, including basement:
(A) In AE, AH, A1 through A30 Zones, elevated to or above the base flood elevation.
(B) In an AO Zone, 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.
(C) In an A zone, without BFEs specified on the FIRM, elevated to or above the base flood elevation; as determined under Section 23.33.040(c)(2).
(ii) 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 submitted to a City building inspector and represented to be properly elevated. Such certification shall be provided to the Floodplain Administrator for review.
(iii) New nonresidential construction or substantial improvements to existing nonresidential construction, shall either be elevated to conform with subsection (a)(3)(i) or together with attendant utility and sanitary facilities:
(A) Be floodproofed below the elevation recommended under subsection (a)(3)(i) 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.
(iv) Flood Openings. All new construction and substantial improvements of structure 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 flood water. Designs for meeting this requirement must meet the following minimum criteria:
(A) For non-engineered openings:
1. Have a minimum of two openings on different sides having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;
2. The bottom of all openings shall be no higher than one foot above grade;
3. Openings may be equipped with screens, louvers, valves or other coverings or devices provided that they permit the automatic entry and exit of floodwater; and
4. Buildings with more than one enclosed area must have openings on exterior walls for each area to allow flood water to directly enter; or
(B) Be certified by a registered civil engineer or architect.
(v) Manufactured homes shall also meet the standards in subsection (e).
(b) Garages and Low Cost Accessory Structures.
(1) Attached Garages.
(i) A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry of flood waters (see subsection (a)(3)). Areas of the garage below the BFE must be constructed with flood resistant materials in accordance with subsection (a)(2).
(ii) A garage attached to a nonresidential structure must meet the above requirements or be dry flood proofed. For guidance on below grade parking areas, see FEMA Technical Bulletin TB-6.
(2) Detached Garages and Accessory Structures.
(i) "Accessory structures," as defined in Section 23.33.020, "Definitions," may be constructed with a floor below the base flood elevation (BFE), 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 BFE 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 BFE;
(E) The accessory structure must comply with floodplain encroachment provisions in this section; and
(F) The accessory structure must be designed to allow for the automatic entry of flood waters in accordance with 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.
(c) Breakaway Walls. A breakaway wall 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) Standards for Utilities.
(1) All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate:
(i) Infiltration of flood waters into the systems; and
(ii) 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.
(e) Standards for Subdivisions. All subdivision proposals must:
(1) Identify the special flood hazard area and the BFE.
(2) Provide the elevation of proposed structure(s) and pad(s). If the site is filled above the BFE, the lowest floor and pad elevations shall be certified by a registered professional engineer or surveyor and provided to the Floodplain Administrator.
(3) Be consistent with the need to minimize flood damage.
(4) Have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.
(5) Provide adequate drainage to reduce exposure to flood hazards.
(f) Standards for Manufactured Homes.
(1) All manufactured homes that are placed or substantially improved, within zones A1 through A30, AH, and AE on the community's Flood Insurance Rate Map, on sites located:
(i) Outside of a manufactured home park or subdivision;
(ii) In a new manufactured home park or subdivision;
(iii) In an expansion to an existing manufactured home park or subdivision; or
(iv) 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 or above the BFE and be securely fastened to an adequately anchored foundation system to resist flotation collapse and lateral movement.
(2) All manufactured homes that are placed or substantially improved on sites located within zones V1 through V30, V, and VE on the community's Flood Insurance Rate Map will meet the requirements of subsection (d)(1).
(3) All manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within zones A1 through A30, AH, AE, V1 through V30, V, and VE on the community's Flood Insurance Rate Map that are not subject to the provisions of subsection (e)(1) will be securely fastened to an adequately anchored foundation system to resist flotation collapse and lateral movement, and be elevated so that either the:
(i) Lowest floor of the manufactured home is at or above the BFE; or
(ii) 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. 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 submitted to the community building inspector and represented to be properly elevated. Such certification shall be provided to the Floodplain Administrator for review.
(g) Standards for Recreational Vehicles.
(1) All recreational vehicles placed on sites within zones A1 through A30, AH, and AE on the Flood Insurance Rate Map will either:
(i) 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) Recreation vehicles placed on sites within zones V1 through V30, V, and VE on the community's Flood Insurance Rate Map will meet the requirements of subsection (e)(1).
(h) Floodways. Since floodways are an extremely hazardous area due to the velocity of flood water which carry debris, potential projectiles, and erosion potential, the following provisions apply:
(1) Until a regulatory floodway is adopted, no new construction, substantial development, or other development (including fill) shall be permitted within zones A1 through A30 and AE, unless it is demonstrated 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 within the City boundary.
(2) Within an adopted regulatory floodway, the City shall prohibit encroachments, including fill, new construction, substantial improvements, and other development, unless certification by a registered civil engineer is provided demonstrating that the proposed encroachment shall not result in any increase in flood levels during the occurrence of the base flood discharge.
(3) All new construction and substantial improvements must comply with all other applicable flood hazard reduction provisions of this section.
(i) Coastal High Hazard Areas. Within coastal high hazard areas as established under Section 23.33.030(b), the following standards shall apply:
(1) 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.
(2) All new construction and other development shall be located on the landward side of the reach of mean high tide.
(3) All new construction and substantial improvements shall have the space below the lowest floor free of obstructions or constructed with breakaway walls. Such enclosed space shall not be used for human habitation and will be usable solely for parking of vehicles, building access or storage.
(4) Fill shall not be used for structural support of buildings.
(5) Man-made alteration of sand dunes which would increase potential flood damage is prohibited.
(6) The Floodplain Administrator shall obtain and maintain the following records:
(ii) 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.