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A. Any activities in a “special flood hazard area” as defined by this chapter shall require a special flood hazard area permit and shall be subject to the requirements of this article, independently of any requirement for a CAAP permit under BMC 14.04.240. These regulations apply to all special flood hazard areas within the boundaries of the city of Bothell.

1. Alteration of Watercourses.

a. Notify adjacent communities and the Department of Ecology prior to such alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administrator through appropriate notification means;

b. Require that maintenance is provided within the altered or relocated portion of said watercourse so that the flood-carrying capacity is not diminished; and

c. Assure that flood-carrying capacity of the altered or relocated portion of said watercourse is maintained.

2. Interpretation of FIRM Boundaries. Make interpretations where needed as to exact location of the boundaries of the areas of special flood hazard (e.g., where there appears to be a conflict between a mapped boundary and actual field conditions). The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation. Such appeals shall be granted consistent with the standards of Section 60.6 of the Rules and Regulations of the National Flood Insurance Program (NFIP).

3. General Standards. In all areas of special flood hazard, the following standards are required:

a. In areas where a regulatory floodway has not been designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within zone AE on the community’s FIRMs, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing development, will not increase the water surface elevation of the base flood more than one foot at any point within the community.

b. Anchoring.

(i) All new construction and substantial improvements, including those related to manufactured homes, shall be 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 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.

c. Construction Materials and Methods.

(i) All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.

(ii) All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.

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

(iv) Buildings located in areas subject to ponding or low-velocity flows must primarily address issues related to hydrostatic loads on the crawlspace foundation, removal of floodwater and sediment from the crawlspace area, and other NFIP floodproofing requirements, such as protecting or elevating utilities and using flood-resistant materials in accordance with FEMA Technical Bulletin 11-01. Crawlspace construction is not recommended in A zones with high-velocity floodwaters (greater than five feet per second). Other types of foundations, such as open pile or column foundations, that allow floodwaters to flow freely beneath the building are recommended for these areas.

d. Utilities.

(i) Utilities shall be located in the 100-year floodplain only when no other physically feasible location is available.

(ii) All new and replacement water supply systems, when permitted in the areas of special flood hazard or 100-year floodplain, shall be designed to minimize or eliminate infiltration of floodwaters into the system. Water wells shall be located on high ground that is not in the floodway.

(iii) Installation of new or replacement sanitary sewage systems in the 100-year floodplain shall be prohibited unless a waiver is granted by the applicable department of public health. If a waiver is granted, the system shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from the system into floodwaters.

(iv) Installation of replacement sanitary sewage systems within the 100-year floodplain shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters.

(v) On-site waste disposal systems, when permitted in the 100-year floodplain, shall be located to avoid impairment to them or contamination from them during flooding.

(vi) Construction of sewage treatment facilities in the 100-year floodplain shall be prohibited.

(vii) Utility transmission lines transporting hazardous substances within the 100-year floodplain shall be buried at a minimum depth of four feet below the maximum depth of scour for the base flood as predicted by a professional civil engineer licensed in the state of Washington and shall achieve sufficient negative buoyancy so that any potential for flotation or upward migration is eliminated.

e. Critical facilities shall not be constructed in the 100-year floodplain.

f. Construction of livestock manure storage facilities and associated nonpoint source water pollution facilities shall not be constructed in the 100-year floodplain.

g. Residential Construction.

(i) In AE or other A-zoned areas where the base flood elevation (BFE) has been determined or can be reasonably obtained, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE. Mechanical equipment and utilities shall be waterproof or elevated at least one foot above the BFE.

(ii) New construction and substantial improvement of any residential structure in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

(iii) 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 (1) have engineered openings designed and certified by a registered professional engineer or architect or (2) 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; and

(D) 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 and exit of floodwaters.

(iv) If buildings or manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage.

h. Nonresidential Construction. New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall meet the requirements of subsection (A)(3)(h)(i) or (A)(3)(h)(ii) of this section:

(i) New construction and substantial improvement of any commercial development shall meet all of the following requirements:

(A) In AE or other A-zoned areas where the BFE has been determined or can be reasonably obtained: New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE, 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 BFE, or as required by ASCE 24, whichever is greater.

(B) If located in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained, the structure shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

(C) 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 for allowing the entry and exit of floodwaters. Designs for meeting this requirement must either (1) have engineered openings designed and certified by a registered professional engineer or architect or (2) meet or exceed the following minimum criteria:

(1) Have 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;

(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) 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 and exit of floodwaters.

(D) If buildings are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage.

(ii) If the requirements of subsection (A)(3)(h)(i) of this section are not met, then new construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall meet all of the following requirements:

(A) Be dry floodproofed so that below one foot or more above the base flood level 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.

(B) Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.

(C) 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 BMC 14.04.740(B).

(D) Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subsection (A)(3)(g) of this section.

(E) 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 the base flood level will be rated as one foot below). Floodproofing the building an additional foot may reduce insurance premiums.

i. Manufactured Homes.

(i) All manufactured homes to be placed or substantially improved within Zones A, AE, and X shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is one foot or more above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.

(ii) If manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage.

j. Subdivision Proposals and Other Development.

(i) All subdivision proposals and any other new development shall be consistent with the need to minimize flood damage.

(ii) Subdivisions, short subdivisions, binding site plans, and any other new development shall follow these requirements:

(A) New building lots shall contain 5,000 square feet or more of buildable land outside the 100-year floodplain and building setback lines shall be shown on the face of the plat to restrict permanent structures to this 5,000-square-foot or greater area;

(B) All public utilities and facilities such as sewer, gas, electrical, and water systems shall be located and constructed consistent with subsection (A)(3)(d) of this section;

(C) Adequate drainage shall be provided to reduce exposure to flood damage;

(D) Where subdivision proposals and other proposed developments contain greater than 50 lots or five acres (whichever is the lesser) base flood elevation data shall be included as part of the application;

(E) Base flood data and flood hazard notes shall be shown on the face of the recorded plat, including, but not limited to, the base flood elevation, required flood protection elevations, and the boundaries of the 100-year floodplain. BFE and required elevations must be reviewed at permit application review to determine if they have changed since the plat or short plat was recorded; and

(F) The following note shall appear on the face of the recorded plat for all affected lots:

NOTICE

Lots and structures located within flood hazard areas may be inaccessible by emergency vehicles during flood events. Residents and property owners should take appropriate advance precautions.

k. Floodways. Located within areas of special flood hazard are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, include potential projectiles, and increase erosion potential, the following provisions apply:

(i) Prohibit encroachments, including fill, new construction, substantial improvements and other development unless certification by a registered professional engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering that the proposed encroachments would not result in any increase in flood levels during the occurrence of the base flood discharge.

(ii) If this subsection is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section.

(iii) Construction or reconstruction of residential structures is prohibited within designated floodways, except for (A) repairs, reconstruction, or improvements to a structure which do not increase the ground floor area; and (B) repairs, reconstruction or improvements to a structure, the cost of which does not exceed 50 percent of the market value of the structure either (1) before the repair, reconstruction, or improvement is started, or (2) 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 toward specifications which have been identified by the local code official and which are the minimum necessary to assure safe living conditions or to structures identified as historic places shall not be included in the 50 percent.

(iv) If residential construction is authorized because subsection (A)(3)(k)(i) of this section is satisfied, or construction is allowed pursuant to (A)(3)(k)(ii) of this section, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section.

l. Recreational Vehicles. Recreational vehicles placed on sites will be required to either:

(i) Be on the site for fewer than 180 consecutive days; or

(ii) Be fully licensed and ready for highway use, on its wheels or jacking system, be attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or

(iii) Meet the requirement of subsection (A)(3)(i) of this section and the elevation and anchoring requirements for manufactured homes.

m. Appurtenant Structures (Detached Garages and Small Storage Structures) and Storage for All A Zones.

(i) Appurtenant structures used solely for parking of vehicles or limited storage may be constructed such that the floor is below the BFE, provided the structure is designed and constructed in accordance with the following requirements:

(A) Use of the appurtenant structure must be limited to parking of vehicles or limited storage;

(B) The portions of the appurtenant structure located below the BFE must be built using flood-resistant materials;

(C) The appurtenant structure must be adequately anchored to prevent flotation, collapse, and lateral movement;

(D) Any machinery or equipment servicing the appurtenant structure must be elevated or floodproofed to or above the BFE;

(E) The appurtenant structure must comply with floodway encroachment provisions in subsection (A)(3)(k)(i) of this section;

(F) The appurtenant structure must be designed to allow for the automatic entry and exit of floodwaters in accordance with subsection (A)(3)(g)(iii) of this section;

(G) The structure shall have low damage potential; and

(H) If the structure is converted to another use, it must be brought into full compliance with the standards governing such use.

(ii) Detached garages, storage structures, and other appurtenant structures not meeting the above standards must be constructed in accordance with all applicable standards in subsection (A)(3)(g)(i) of this section.

(iii) Meet the requirement of subsection (A)(3)(i) of this section and the elevation and anchoring requirements for manufactured homes.

(iv) The storage or processing of materials that could be injurious to human, animal, or plant life if released due to damage from flooding is prohibited in special flood hazard areas.

(v) Storage of other material or equipment may be allowed if not subject to damage by floods and if firmly anchored to prevent flotation, or if readily removable from the area within the time available after flood warning.

B. General Requirements for Other Development. All development, including manmade changes to improved or unimproved real estate for which specific provisions are not specified in this chapter or the building codes with adopted amendments and any city of Bothell amendments, shall:

1. Be located and constructed to minimize flood damage;

2. Meet the encroachment limitations of this chapter if located in a regulatory floodway;

3. Be anchored to prevent flotation, collapse, or lateral movement resulting from hydrostatic loads, including the effects of buoyancy, during conditions of the design flood;

4. Be constructed of flood-damage-resistant materials;

5. Meet the flood opening requirements of subsection (A)(3) of this section; and

6. Have mechanical, plumbing, and electrical systems above the design flood elevation or meet the requirements of ASCE 24, except that minimum electric service required to address life safety and electric code requirements is permitted below the design flood elevation provided it conforms to the provisions of the electrical part of the building code for wet locations. (Ord. 2315 § 18, 2020; Ord. 1946 § 3, 2005).