A. Standards of Construction. In all special flood hazard areas, the following standards are required:
1. Anchoring.
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 Section 15.60.050D1.
2. Construction Materials and Methods. All new construction and substantial improvements of structures, including manufactured homes, shall be constructed:
a. With materials, which are located below the BFE, that are flood damage resistant per FEMA Technical Bulletin 2-08; and
b. Using methods and practices that minimize flood damage; and
c. With mechanical, electrical and plumbing systems and other service systems that are either elevated above the BFE if possible or, if below the BFE, designed to prevent water from entering or accumulating within the system components during conditions of flooding per FEMA 348.
3. Elevation and Floodproofing. (See Section 15.60.020, definitions for “Basement,” “Lowest floor,” “New construction,” “Substantial damage” and “Substantial improvement.”)
a. Residential construction. All new construction or substantial improvements of residential structures shall have the lowest floor, including basement:
i. In an AE Zone, elevated to or above the BFE.
ii. In an A zone, without BFE's specified on the FIRM [unnumbered A zone], elevated to or above the BFE; as determined under Section 15.60.040C2.
iii. Certified by a registered professional engineer or land surveyor, and verified by the city building inspector, to be properly elevated prior to issuance of the final inspection of the structure. Such certification and verification shall be provided to the floodplain administrator.
b. Nonresidential construction. All new or substantial improvements of nonresidential structures shall either be elevated to conform with Section 15.60.050A3a or together with attendant utility and sanitary facilities:
i. Be floodproofed to one (1) foot above the BFE so that the structure is watertight with walls substantially impermeable to the passage of water and eligible to receive an insurance rate equivalent to a building with its lowest floor elevated to the BFE;
ii. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
iii. Be certified by a registered professional engineer or architect, and verified by the city building inspector, that the floodproofing requirements of this Section 15.60.050A3b are satisfied prior to issuance of final occupancy of the structure. Such certification shall be provided to the floodplain administrator.
c. Flood Openings. All new construction and substantial improvements of structures with fully enclosed areas below the lowest floor (excluding basements) that are usable solely for parking of vehicles, building access, building crawlspace or storage, and which are subject to flooding, shall:
i. Be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwater.
ii. Be designed to provide a minimum of two (2) openings on different exterior walls 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. Buildings with more than one (1) enclosed area shall have two (2) openings on different exterior walls for each enclosed area to allow the automatic entry and exit of floodwater in each enclosed area.
iii. Be certified by a registered professional engineer or architect, and verified by the city building inspector, that the flood openings requirements of this Section 15.60.050A3c are satisfied prior to issuance of the final inspection of the structure. Such certification shall be provided to the floodplain administrator.
d. Manufactured homes shall meet the standards in Section 15.60.050D.
e. Crawlspace Construction. This sub-section applies to buildings with crawlspaces up to two (2) feet below grade. Below-grade crawlspace construction that is done in accordance with the requirements listed below will not be considered to be a basement.
i. Crawlspace construction shall be done per the guidance provided in FEMA Technical Bulletin 11-01.
ii. The building shall be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Crawlspace construction is not allowed at sites with flood velocities greater than five (5) feet per second and other foundation types should be used;
iii. The crawlspace is a fully enclosed area below the BFE and, as such, shall have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. For guidance on flood openings, see FEMA Technical Bulletin 1-08;
iv. Crawlspace construction is not permitted in V zones. Open pile or column foundations that withstand storm surge and wave forces are required in V zones;
v. Portions of the building below the BFE shall be constructed with materials that are flood damage resistant per FEMA Technical Bulletin 2-08. This includes not only the foundation walls of the crawlspace used to elevate the building, but also any joists, insulation, or other materials that extend below the BFE; and
vi. Any mechanical, electrical and plumbing systems located within the crawlspace shall be elevated above the BFE if possible or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions per FEMA 348.
vii. Requirements for all below-grade crawlspace construction, in addition to the above requirements, to include the following:
(a) The interior grade of a crawlspace below the BFE shall not be more than two (2) feet below the lowest adjacent exterior grade (LAG), shown as D in figure 3 of Technical Bulletin 11-01;
(b) The height of the below-grade crawlspace, measured from the interior grade of the crawl space to the top of the crawlspace foundation wall shall not exceed 4 feet (shown as L in figure 3 of Technical Bulletin 11-01) at any point; and
(c) There shall be an adequate drainage system that removes floodwaters from the interior area of the crawlspace within a reasonable period of time after a flood event, not to exceed seventy-two (72) hours.
B. Standards for Utilities.
1. All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from systems into floodwaters.
2. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
C. Standards for Subdivisions and Other Residential Development.
1. All new subdivisions proposals and other proposed residential development, including proposals for manufactured home parks and subdivisions, greater than ten (10) lots or three (3) acres, whichever is the lesser, shall:
a. Identify the location of the SFHA and label the BFE lines on the record map.
b. Identify the elevations of lowest floors of all proposed structures and pads on the record map and construction plans.
c. Place fill to raise the pads for the structures to or above the BFE. The following as-built information shall be certified by a registered civil engineer or licensed land surveyor and included as part of an application for a Letter of Map Revision based on Fill (LOMR-F) to FEMA:
i. Lowest lot elevation or pad elevation.
ii. Lowest adjacent grade to structure. (for cases with existing structures)The application for the LOMR-F shall be submitted to the floodplain administrator for review prior to submission to FEMA. The floodplain administrator shall complete the community acknowledgement form (FEMA Form 81-87B) for inclusion with the application.
2. All subdivision proposals and other proposed residential development shall be consistent with the need to minimize flood damage.
3. All subdivision proposals and other proposed residential development shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.
4. All subdivision proposals and other proposed residential development shall provide adequate drainage to reduce exposure to flood hazards and shall comply with the provisions of Section 15.60.050F1.
D. Standards for Manufactured Homes.
1. All manufactured homes that are placed or substantially improved, 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 upon which a manufactured home has incurred “substantial damage” as the result of a flood, shall:
a. Within Zone AE on the community's FIRMs, 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.
b. Be certified by a registered professional engineer or land surveyor, and verified by the city or state building inspector, that the lowest floor (including basement) is properly elevated prior to issuance of the final inspection of the structure. Such certification and verification shall be provided to the floodplain administrator.
2. All manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within Zone AE on the community's FIRMs that are not subject to the provisions of Section 15.60.050D1 shall:
a. Be securely fastened to an adequately anchored foundation system to resist flotation, collapse, and lateral movement; and
b. Be elevated so that either:
i. The lowest floor of the manufactured home is at or above the BFE; or
ii. The chassis of the manufactured home 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. Be certified by a registered professional engineer or land surveyor, and verified by the city or state building inspector, that the lowest floor (including basement) is properly elevated prior to issuance of the final inspection of the structure. Such certification and verification shall be provided to the floodplain administrator.
E. Standards for Recreational Vehicles.
1. All recreational vehicles placed on sites within Zone AE on the community's FIRMs will either:
a. Be on the site for fewer than one hundred eighty (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
F. Regulatory Floodways. FEMA has stated in the FIS that the city is characterized as an urbanized, inactive alluvial fan system, which consists of highly trained creeks and irrigation channels. This system of creeks and channels does not have the capacity to contain the base flood and therefore the establishment of regulatory floodways is not possible. The resulting flooding from the base flood consists of areas of shallow flooding with overland flows characterized by relatively stable flow paths through the community with flow velocities ranging from 0.5 to 2.0 feet per second. This velocity range of the flood flows is considered low and not extremely hazardous; therefore, the following provisions apply:
1. New construction, substantial development, or other development (including fill) shall be permitted within Zone AE when 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 (1) foot at any point within the city, or alternatively, it is demonstrated: (1) that the proposed development does not substantially increase the water surface elevation of the base flood within the vicinity of the proposed development, and (2) the proposed development is designed to allow the flow of the base flood to substantially pass through. This analysis shall be done under the direction of the floodplain administrator and upon satisfactory completion shall be prepared into a report to be accepted by the floodplain administrator.