In all areas of special flood hazard, the following standards are required.
(Ord. 673 § 2, 2024)
(1)
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 (44 CFR 60.3(a)(3)(i)).
(2)
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 (44 CFR 60.3(b)(8)). For more detailed information, refer to guidebook, FEMA-85, “Manufactured Home Installation in Flood Hazard Areas.”
(Ord. 673 § 2, 2024)
(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 designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
(Ord. 673 § 2, 2024)
(1)
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.
(2)
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.
(Ord. 673 § 2, 2024)
(1)
All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems;
(2)
Water wells 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 floodwaters into the systems and discharges from the systems into floodwaters;
(4)
On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
(Ord. 673 § 2, 2024)
All subdivisions, as well as new development, shall:
(1)
Be consistent with the need to minimize flood damage;
(2)
Have public utilities and facilities, such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage;
(3)
Have adequate drainage provided to reduce exposure to flood damage;
(4)
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.
(Ord. 673 § 2, 2024)
In all areas of special flood hazards where base flood elevation data has been provided as set forth in FMC § 14.05.320, Basis for establishing the areas of special flood hazard, or 14.05.432, Use of other base flood data (in A zones), the following provisions are required.
(Ord. 673 § 2, 2024)
(1)
In AE and A1-30 zones or other A zoned areas where the 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 waterproofed or elevated at least one foot above the BFE.
(2)
New construction and substantial improvement of any residential structure in an AO zone shall meet the requirements in FMC § 14.05.580.
(3)
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.
(4)
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 must meet or exceed the following minimum criteria:
(a)
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.
(b)
The bottom of all openings shall be no higher than one foot above grade.
(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.
(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.
Alternatively, a registered engineer or architect may design and certify engineered openings.
(Ord. 673 § 2, 2024)
New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet the requirements of subsection (1) or (2) of this section.
(1)
New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:
(a)
In AE and A1-30 zones 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 non-residential 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.
(c)
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.
(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)
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.
(ii)
The bottom of all openings shall be no higher than one foot above grade.
(iii)
Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.
(iv)
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.
Alternatively, a registered engineer or architect may design and certify engineered openings.
(2)
If the requirements of subsection (1) 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 FMC § 14.05.432;
(d)
Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in FMC § 14.05.521(4).
Note: Applicants who are 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 will reduce insurance premiums significantly.
(Ord. 673 § 2, 2024)
All manufactured homes to be placed or substantially improved on sites shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated 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.
(Ord. 673 § 2, 2024)
(1)
Recreational vehicles placed on sites are required to either:
(Ord. 673 § 2, 2024)
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.
(Ord. 673 § 2, 2024)
(1)
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;
(f)
The appurtenant structure must be designed to allow for the automatic entry and exit of floodwaters in accordance with FMC § 14.05.521(4);
(g)
The structure shall have low damage potential;
(h)
If the structure is converted to another use, it must be brought into full compliance with the standards governing such use; and
(i)
The structure shall not be used for human habitation.
(3)
Upon completion of the structure, certification that the requirements of this section have been satisfied shall be provided to the floodplain administrator for verification.
(Ord. 673 § 2, 2024)
In areas with BFEs (but a regulatory floodway has not been designated), no new construction, substantial improvements, or other development (including fill) shall be permitted within zones A1-30 and AE on the community’s FIRM, 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 foot at any point within the community.
(Ord. 673 § 2, 2024)
Located within areas of special flood hazard established in FMC § 14.05.320 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters that can carry debris, and increase erosion potential, the following provisions apply.
(Ord. 673 § 2, 2024)
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 practice that the proposed encroachment would not result in any increase in flood levels during the occurrence of the base flood discharge (44 CFR 60.3(d)(3)).
(Ord. 673 § 2, 2024)
(1)
Construction or reconstruction of residential structures is prohibited within designated floodways, except for (a) repairs, reconstruction, or improvements to a structure that 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 (i) before the repair or reconstruction is started or (ii) 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 that have been identified by the local code enforcement official and that are the minimum necessary to assure safe living conditions, or to structures identified as historic places, may be excluded in the 50 percent.
(2)
Replacement of Farmhouses in Floodway. Repairs, reconstruction, replacement, or improvements to existing farmhouse structures located in designated floodways and that are located on lands designated as agricultural lands of long-term commercial significance under RCW 36.70A.170 may be permitted subject to the following:
(a)
The new farmhouse is a replacement for an existing farmhouse on the same farm site;
(b)
There is no potential building site for a replacement farmhouse on the same farm outside the designated floodway;
(c)
Repairs, reconstruction, or improvements to a farmhouse shall not increase the total square footage of encroachment of the existing farmhouse;
(d)
A replacement farmhouse shall not exceed the total square footage of encroachment of the farmhouse it is replacing;
(e)
A farmhouse being replaced shall be removed, in its entirety, including foundation, from the floodway within 90 days after occupancy of a new farmhouse;
(f)
For substantial improvements and replacement farmhouses, the elevation of the lowest floor of the improvement and farmhouse respectively, including basement, is a minimum of one foot higher than the BFE;
(g)
New and replacement water supply systems are designed to eliminate or minimize infiltration of floodwaters into the system;
(h)
New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of floodwater into the system and discharge from the system into the floodwaters; and
(i)
All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage.
(3)
Substantially Damaged Residences in Floodway.
(a)
For all substantially damaged residential structures, other than farmhouses, located in a designated floodway, the floodplain administrator may make a written request that the Department of Ecology assess the risk of harm to life and property posed by the specific conditions of the floodway. Based on analysis of depth, velocity, flood-related erosion, channel migration, debris load potential, and flood warning capability, the Department of Ecology may exercise best professional judgment in recommending to the local permitting authority repair, replacement, or relocation of a substantially damaged structure consistent with WAC 173-158-076. The property owner shall be responsible for submitting to the local government and the Department of Ecology any information necessary to complete the assessment. Without a favorable recommendation from the Department for the repair or replacement of a substantially damaged residential structure located in the regulatory floodway, no repair or replacement is allowed per WAC 173-158-070(1).
(b)
Before the repair, replacement, or reconstruction is started, all requirements of the NFIP, the state requirements adopted pursuant to Chapter 86.16 RCW, and all applicable local regulations must be satisfied. In addition, the following conditions must be met:
(i)
There is no potential safe building location for the replacement residential structure on the same property outside the regulatory floodway;
(ii)
A replacement residential structure is a residential structure built as a substitute for a legally existing residential structure of equivalent use and size;
(iii)
Repairs, reconstruction, or replacement of a residential structure shall not increase the total square footage of floodway encroachment;
(iv)
The elevation of the lowest floor of the substantially damaged or replacement residential structure is a minimum of one foot higher than the BFE;
(v)
New and replacement water supply systems are designed to eliminate or minimize infiltration of floodwater into the system;
(vi)
New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of floodwater into the system and discharge from the system into the floodwaters;
(vii)
All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage.
(Ord. 673 § 2, 2024)
All development, including manmade changes to improved or unimproved real estate for which specific provisions are not specified in this chapter or the state building codes with adopted amendments and any city of Forks 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 FMC § 14.05.521(4); 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 building code for wet locations.
(Ord. 673 § 2, 2024)
Construction of new critical facilities shall be, to the extent possible, located outside the limits of the SFHA (100-year floodplain). Construction of new critical facilities shall be permissible within the SFHA if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor elevated three feet above BFE or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility should also be protected to the height utilized above. 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 BFE shall be provided to all critical facilities to the extent possible.
(Ord. 673 § 2, 2024)
Elevated areas for the purpose of creating a flood sanctuary for livestock are allowed on farm units where livestock is allowed. Livestock flood sanctuaries shall be sized appropriately for the expected number of livestock and be elevated sufficiently to protect livestock. Proposals for live-stock flood sanctuaries shall meet all procedural and substantive requirements of this chapter.
Note: To be “elevated sufficiently to protect livestock” typically means to be elevated at least one foot above the BFE.
(Ord. 673 § 2, 2024)
Shallow flooding areas appear on FIRMs as AO zones with depth designations. The base flood depths in these zones range from one to three feet above ground where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. In addition to other provisions in this code, the following additional provisions also apply in AO zones:
(1)
New construction and substantial improvements of residential structures and manufactured homes within AO zones shall have the lowest floor (including basement and mechanical equipment) elevated above the highest adjacent grade to the structure one foot or more above the depth number specified in feet on the community’s FIRM (at least two feet above the highest adjacent grade to the structure if no depth number is specified).
(2)
New construction and substantial improvements of nonresidential structures within AO zones shall either:
(a)
Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site one foot or more above the depth number specified on the FIRM (at least two feet if no depth number is specified); or
(b)
Together with attendant utility and sanitary facilities, be completely floodproofed to or above that level so that any space below that level is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect as in FMC § 14.05.522(3).
(3)
Require adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures.
(4)
Recreational vehicles placed on sites within AO zones on the community’s FIRM either:
(a)
Be on the site for fewer than 180 consecutive days; or
(b)
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
(c)
Meet the requirements of subsections (1) and (3) of this section and the anchoring requirements for manufactured homes (FMC § 14.05.511(2)).
(Ord. 673 § 2, 2024)