40.420.020    Standards

A.    Uses.

1.    Allowed Uses in Special Flood Hazard Areas.

a.    Outside of shoreline jurisdiction, development may be allowed for those uses in the underlying zoning district with a flood hazard permit pursuant to Section 40.420.030(D).

b.    Within shoreline jurisdiction, development may be allowed for those uses allowed in the shoreline master program, with a flood hazard permit pursuant to Section 40.420.030(D) as part of the shoreline permit process.

c.    Park, recreational, agricultural and other similar open space uses allowed in the underlying zoning district, which do not involve development as defined in this chapter, are permitted outright in special flood hazard areas.

2.    Prohibited Uses in Special Flood Hazard Areas.

a.    Construction or reconstruction of residential structures is prohibited in the floodway except, in accordance with Chapter 86.16 RCW, for repairs, reconstruction, or improvements to a lawfully established structure:

(1)    Which do not increase the ground floor area; and

(2)    That are not a substantial improvement.

b.    Floodway encroachments are prohibited unless certification by a licensed professional engineer registered in the state of Washington is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge. If it has been adequately demonstrated through calculations that the encroachment will not result in increased flood levels, all new nonresidential construction and nonresidential substantial improvements shall comply with all applicable flood hazard reduction provisions of this chapter.

3.    Special Flood Hazard Area with Base Flood Elevation but No Floodways. In areas with base flood elevation but where a regulatory floodway has not been designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within Zone AE, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one (1) foot at any point in the county.

(Amended: Ord. 2005-04-15; Ord. 2012-07-15)

B.    Land Divisions.

    All land divisions shall:

1.    Identify lots and portions of lots in special flood hazard areas as part of preliminary plat submittal;

2.    Be designed to minimize flood damage;

3.    Have any public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage;

4.    Have roadways designed such that, in the event of a one-hundred- (100-) year flood, one (1) travel lane in either direction shall not be covered by more than six (6) inches of water; and

5.    Have adequate drainage provided to reduce exposure to flood damage.

(Amended: Ord. 2005-04-15; Ord. 2012-07-15)

C.    Building Permits.

    Permits for buildings and structures in special flood hazard areas are subject to the requirements of this chapter.

(Amended: Ord. 2005-04-15; Ord. 2012-07-15)

D.    General Construction Standards.

    In all special flood hazard areas, the following standards shall be met:

1.    Anchoring, in Accordance with FEMA Requirements.

a.    All new construction and any substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.

b.    All manufactured homes shall be anchored to prevent flotation, collapse or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors, and additional techniques referenced in the current FEMA guidebook FEMA P-85, “Protecting Manufactured Homes From Floods and Other Hazards.”

2.    Construction Materials and Methods, in Accordance with FEMA Technical Bulletin 2.

a.    All new construction and any substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.

b.    All new construction and any substantial improvements shall be constructed using methods and practices that minimize flood damage.

c.    Electrical, heating, ventilation, plumbing, and air-conditioning equipment and other service facilities shall be designed, elevated and located so as to prevent water from entering or accumulating within the components during flooding.

3.    Utilities.

a.    All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.

b.    Water wells shall not be located in the floodway or in areas subject to ponding.

c.    All new and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters.

d.    On-site waste disposal systems shall be located or designed to avoid impairment to them or contamination from them during flooding.

(Amended: Ord. 2005-04-15; Ord. 2012-07-15)

E.    Specific Construction Standards.

    In all special flood hazard areas, once base flood elevation data has been provided as required in Section 40.420.010(D)(1), or as established in Section 40.420.010(D)(2), the following standards shall be met:

1.    Residential Construction.

a.    New residential construction and substantial improvement of any residential structure shall have the lowest floor (including the basement) elevated at least one (1) foot above base flood elevation.

b.    Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, unless designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of flood waters. Designs for meeting this requirement must either be certified by a licensed professional engineer registered in the state of Washington or must meet or exceed the following minimum criteria:

(1)    A minimum of two (2) openings having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding shall be provided;

(2)    The bottom of all openings shall be no higher than one (1) foot above grade; and

(3)    Openings may be equipped with screens, louvers, or other coverings or devices, provided they permit the automatic entry and exit of floodwaters.

c.    Below-Grade Crawl Spaces.

(1)    Below-grade crawl spaces will not be considered basements if constructed to the following criteria:

(a)    The interior grade of the crawl space is not more than two (2) feet below the lowest adjacent exterior grade.

(b)    The height of the below-grade crawl space, measured from the interior grade of the crawl space to the top of the crawl space foundation wall, must not exceed four (4) feet at any point. The height limitation is the maximum allowable unsupported wall height according to the engineering analyses and building code requirements for flood hazard areas.

(c)    There must be an adequate drainage system that removes floodwaters from the interior area of the crawl space.

(d)    The velocity of floodwaters at the site should not exceed five (5) feet per second for any crawl space. For velocities in excess of five (5) feet per second, other foundation types should be used.

(e)    Utility systems within the crawl space, particularly ductwork, must be elevated above the base flood elevation, or designed so that floodwaters cannot enter or accumulate within system components, or be damaged during flood conditions.

(f)    All insulation must be located above the base flood elevation.

(2)    Buildings that have below-grade crawl spaces may have higher flood insurance premiums than buildings that have the preferred crawl space construction with the interior elevation at or above the lowest adjacent grade.

(3)    For additional information and diagrams see FEMA Technical Bulletin 11.

2.    Nonresidential Construction.

a.    New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall either have the lowest floor, including the basement, elevated to at least one (1) foot above base flood elevation; or, together with attendant utility facilities, shall:

(1)    Be floodproofed so that the structure is watertight with walls substantially impermeable to the passage of water up to an elevation one (1) foot above the base flood elevation;

(2)    Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and

(3)    Be certified by a licensed professional engineer registered in the state of Washington that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be on FEMA Form 81-65 and provided to the responsible official as set forth in Section 40.420.030(D).

b.    Nonresidential structures that are elevated, but not floodproofed, must meet the same standards for space below the lowest floor as described in Section 40.420.020(E)(1)(b).

c.    Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates for floodproofing to one (1) foot below the floodproofed level.

3.    Manufactured Homes. All manufactured homes to be placed or substantially improved within a special flood hazard area shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at least one (1) foot above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement in accordance with the provisions of Section 40.420.020(D)(1)(b).

4.    Travel Trailers and Recreational Vehicles. Travel trailers and recreational vehicles are allowed as follows:

a.    In a floodway between May 1st and September 30th of the same year.

b.    In a special flood hazard area outside of a floodway on a temporary basis for fewer than one hundred eighty (180) consecutive days unless:

(1)    The vehicle remains fully licensed or has a valid trip permit from the Washington State Department of Licensing and is ready for highway use, on wheels or a jacking system, attached to the site only by quick disconnect type utilities and security devices, and with no permanently attached additions; or

(2)    The requirements of Section 40.420.020(E)(3) are met.

5.    Critical Facilities.

a.    New critical facilities shall be constructed outside of special flood hazard areas unless no feasible alternative sites are available.

b.    Critical facilities constructed within special flood hazard areas shall have:

(1)    The lowest floor elevated three (3) feet above the base flood elevation or to the height of the five-hundred- (500-) year flood, whichever is higher;

(2)    Access to and from the critical facility as required in Section 40.420.020(B)(4); and

(3)    Floodproofing and sealing measures to ensure that toxic substances will not be displaced by or released into floodwaters.

(Amended: Ord. 2005-04-15; Ord. 2012-07-15)