30.65.120 Floodproofing: specific standards.
In all special flood hazard areas where base elevation data has been provided as set forth in SCC 30.65.100, the following regulations shall apply, in addition to the general regulations of SCC 30.65.110:
(1) All electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities that are permanently affixed to a structure and which may be subject to floodwater damage shall be elevated a minimum of one foot above the base flood elevation or higher (unless within an approved watertight structure).
(2) Residential construction.
(a) In AE and A1-30 zones or other A zoned areas, where the base flood elevation has been determined, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated a minimum of one foot above the base flood elevation. Mechanical equipment and utilities shall be waterproof or elevated at least one foot above base flood elevation.
(b) New construction and substantial improvement of any residential structure in an AO zone shall meet the requirements in SCC 30.65.290.
(c) New construction and substantial improvement of any residential structure in a V, V1-30, or VE zone shall meet the requirements in SCC 30.65.295.
(d) Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:
(i) 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 shall be provided;
(ii) the bottom of all openings shall be no higher than one foot above the interior and exterior lowest grades;
(iii) openings may be equipped with screens, louvers, or other coverings or devices only if they permit the automatic entry and exit of floodwaters; and
(iv) a garage attached to a residential structure, that is constructed with the garage floor slab below the base flood elevation, shall be designed to allow the automatic entry and exit of floodwaters.
(3) Nonresidential construction. New construction and substantial improvements of nonresidential structures shall comply with either subsection (3)(a) or (3)(b) of this section:
(a) Be elevated consistent with the following standards:
(i) In AE or unnumbered A zoned areas where the base flood elevation has been determined, structures shall have the lowest floor, including basement, elevated one foot or more above the base flood elevation, or elevated as required by ASCE 24, whichever is greater. Mechanical equipment and utilities shall be waterproofed or elevated at least one foot above the base flood elevation, or as required by ASCE 24, whichever is greater.
(ii) In AO zones, structures shall meet the requirements of SCC 30.65.290.
(iii) In V or VE zones, structures shall meet the requirements of SCC 30.65.295.
(iv) Fully enclosed areas below the lowest floor that are subject to flooding are prohibited unless they are designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters and they comply with SCC 30.65.110(4). Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:
(A) a minimum of two openings with a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;
(B) the bottom of all openings shall be no higher than one foot above grade; and
(C) openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
(b) Be dry floodproofed so that below one foot or more above the base flood elevation the structure is watertight with walls substantially impermeable to the passage of water or dry floodproofed to the elevation required by ASCE 24, whichever is greater. The following standards also apply:
(i) Structural components shall be capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
(ii) The structure shall be certified by a registered professional engineer or architect that the design and methods of construction meet accepted standards of practice and satisfy the provisions of subsection (3)(b) of this section based on their development or review of the structural design, specifications, and plans. The certifications shall be provided to the floodplain administrator pursuant to SCC 30.65.130.
(4) Mobile homes.
(a) All mobile homes that are placed or substantially improved in special flood hazard areas shall be elevated on a permanent foundation and shall be securely anchored to an adequately anchored foundation system in accordance with SCC 30.65.110(1)(b) to resist flotation, collapse and lateral movement, and shall have the lowest floor elevated a minimum of one foot above the base flood elevation.
(5) Critical facilities as defined in SCC 30.91C.360 shall have the lowest floor elevated to three feet or more above the level of the base flood elevation at the site. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into flood waters. Access routes elevated to or above the level of the base flood plain shall be provided to all critical facilities to the extent possible.
(6) Recreational vehicles, when otherwise permitted by county code, shall
(b) Be fully licensed and ready for highway use, on wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; and
(c) Be limited in the floodways to day use only (dawn to dusk) during the flood season (October 1st through March 30th) with the following exceptions:
(i) Recreational vehicle use associated with a legally occupied dwelling to accommodate overnight guests for no more than a 21-day period;
(ii) Temporary overnight use by farm workers on the farm where they are employed subject to SCC 30.22.130(19)(a) and (19)(b); and
(iii) Subject to SCC 30.22.130(19)(a) and (19)(b), temporary overnight use in a mobile home park which has been in existence continuously since 1970 or before, that provides septic or sewer service, water and other utilities, and that has an RV flood evacuation plan that has been approved and is on file with the department of emergency management and department of planning and development services.
(7) When fill is permitted to be used as an elevation/floodproofing technique, it shall be designed and installed so that it is properly compacted, sloped and armored to resist potential flood velocities, scouring and erosion during flooding.
(8) Flood hazard permits issued for wet floodproofing of any structure or for elevated structures having enclosures below the elevated structure that are wet floodproofed shall be subject to a standard permit condition prohibiting human habitation. The conditions shall be recorded on title on a form approved by the department. (Added by Amended Ord. 02-064, Dec. 9, 2002, Eff date Feb. 1, 2003; Amended by Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005; Amended by Amended Ord. 07-005, Feb. 21, 2007, Eff date Mar. 4, 2007; Amended by Ord. 20-076, Nov. 4, 2020, Eff date Nov. 27, 2020).