Article IV. - Provisions for Flood Hazard Reduction

15.12.190 - General standards.

In all areas of special flood hazards, the following standards are required:

A. Anchoring.

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

2. All manufactured homes must likewise 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 (reference FEMA's "Manufactured Home Installation in Flood Hazard Areas" guidebook for additional techniques).

B.   Construction Materials and Methods.
                  1.   All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood
                     damage.
                  
2.   All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
3.   Electrical, heating, ventilation, plumbing, and air-conditioning equipment and other service facilities shall be designated
                     and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions
                     of flooding.
                  

C.   Utilities.
                  1.   All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the
                     system;
                  
2.   The proposed water well shall be located on high ground that is not in the floodway (WAC 173-160-171);
3.   New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the
                     systems and discharge from the systems into flood waters; and
                  
4.   On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

D.   Subdivision Proposals.
                  1.   All subdivision proposals shall be consistent with the need to minimize flood damage;
2.   All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located
                     and constructed to minimize flood damage;
                  
3.   All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and
4.   Where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated
                     for subdivision proposals and other proposed developments which contain at least fifty (50) lots or five acres (whichever
                     is less).
                  

E. Review of Building Permits. Where elevation data is not available either through the flood insurance study or from another authoritative source (Section 15.12.160(B)), applications for building permits shall be reviewed to assure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. Failure to elevate at least two feet above grade in these zones may result in higher insurance rates.

(Ord. 514 (part), 1999; Ord. 367 § 5.1, 1988)

15.12.200 - Specific standards.

In all areas of special flood hazards where base flood elevation data has been provided as set forth in Section 15.12.080, Basis for Establishing the Areas of Special Flood Hazard, or Section 15.12.160(B), Use of Other Base Flood Data, the following provisions are required:

A. Residential Construction.

1. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one foot or more above base flood elevation.

2.   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:
                     a.   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.
                     
b.   The bottom of all openings shall be no higher than one foot above grade.
c.   Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry
                        and exit of floodwaters.
                     

B.   Nonresidential Construction. New construction and substantial improvement of any commercial, industrial or other nonresidential
                  structure shall either have the lowest floor, including basement, elevated one foot or more above the level of the base flood
                  elevation, or, together with attendant utility and sanitary facilities, shall:
                  1.   Be floodproofed so that below one foot above the base flood level the structure is watertight with walls substantially impermeable
                     to the passage of water;
                  
2.   Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
3.   Be certified by a registered professional engineer or architect 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 provided to the official as set forth in Section
                     15.12.160(C)(2);
                  
4.   Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor
                     as described in Section 15.12.200(A)(2);
                  
5.   Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that
                     are one foot below the floodproofed level (e.g. a building floodproofed to one foot above the base flood level will be rated
                     as at the base flood level).
                  

C. Critical Facility. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the base floodplain. Construction of new critical facilities shall be permissible within the base floodplain if no feasible alternative site is available. Critical facilities constructed within the base floodplain 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 floodwaters. Access routes elevated to or above the level of the base floodplain shall be provided to all critical facilities to the extent possible.

D. Manufactured Homes.

1.   All manufactured homes to be placed or substantially improved within Zones A1-A30, AH, and AE on the community's FIRM on sites:
                     a.   Outside of a manufactured home park or subdivision;
b.   In a new manufactured home park or subdivision;
c.   In an expansion to an existing manufactured home park or subdivision; or
d.   In an existing manufactured home park or subdivision on 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 one foot above
                        the base flood elevation and be securely anchored to an adequately designed foundation system to resist flotation, collapse
                        and lateral movement.
                     

2. Manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within Zones A1-30, AH, and AE on the community's FIRM that are not subject to the above manufactured home provisions shall be elevated so that either:

a. The lowest floor of the manufactured home is elevated one foot above the base flood elevation; or

b. The manufactured home chassis 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 and be securely anchored to an adequately designed foundation system to resist flotation, collapse, and lateral movement.

E.   Recreational Vehicles. Recreational vehicles placed on sites within Zones A1-30, AH, and AE on the community's FIRM either:
                  1.   Be on the site for fewer than one hundred eighty (180) consecutive days,
2.   Be fully licensed and ready for highway use, 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
                  
3.   Meet the requirements of subsection D of this section and the elevation and anchoring requirements for manufactured homes.

(Ord. 514 (part), 1999; Ord. 367 § 5.2, 1988)

15.12.210 - Floodways.

Located within areas of special flood hazard established in Section 15.12.080 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles, and erosion potential, the following provisions apply:

A. Prohibit encroachments, including fill, new construction, substantial improvements, and other development unless certification by a registered professional engineer or architect is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge;

B. Construction or reconstruction of residential structures is prohibited within designated floodways, except for (1) repairs, reconstruction or improvements to a structure which do not increase the ground floor area; and (2) repairs, reconstruction or improvements to a structure, the cost of which does not exceed fifty (50) percent of the market value of the structure, either (a) before the repair or reconstruction is started, or (b) if the structure has been damaged, and is being restored, before the damage occurred. Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement officials and which are the minimum necessary to assure safe living conditions or to structures identified as historic places shall not be included in the fifty (50) percent.

C. If subsection A of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of Article IV, Provisions for Flood Hazard Reduction.

(Ord. 514 (part), 1999; Ord. 367 § 5.3, 1988)

15.12.220 - Wetlands management.

To the maximum extent possible, developers should avoid the short- and long-term adverse impacts associated with the destruction or modification of wetlands, especially those activities which limit or disrupt the ability of the wetland to alleviate flooding impacts. The following process should be implemented:

A. Review proposals for development within base floodplains for their possible impacts on wetlands located within the floodplain;

B. Ensure that development activities in or around wetlands do not negatively affect public safety, health and welfare by disrupting the wetlands' ability to reduce flood and storm drainage;

C. Request technical assistance from the Department of Ecology in identifying wetland areas. Existing wetland map information from the National Wetlands Inventory (NWI) can be used in conjunction with the community's FIRM to prepare an overlay zone indicating critical wetland areas deserving special attention.

(Ord. 367 § 5.4, 1988)