Chapter 2.05 FLOOD HAZARD PREVENTION

Unless specifically defined below, words or phrases used in this chapter shall be interpreted so as to give them the meaning they have in common usage and to give this chapter its most reasonable application.

“Alteration of watercourse” means any action that will change the location of the channel occupied by water within the banks of any portion of a riverine water body.

“Appeal” means a request for a review of the interpretation of any provision of this chapter or a request for a variance.

“Area of shallow flooding” means a designated AO, AH, AR/AO or AR/AH (or VO) zone on the flood insurance rate map (FIRM) with a one percent or greater annual chance of flooding to an average depth range from one to three feet; a clearly defined channel does not exist; the path of flooding is unpredictable and indeterminate; and velocity flow may be evident. Such flooding is characterized by ponding or sheet flow. Also referred to as the sheet flow area.

“Area of special flood hazard” means the land in the floodplain within a community subject to a one percent or greater chance of flooding in any given year. It is shown on the flood insurance rate map (FIRM) as zone A, AO, AH, A1-30, AE, A99, AR (V, VO, V1-30, VE). “Special flood hazard area” is synonymous in meaning with the phrase “area of special flood hazard.”

“ASCE 24” means the most recently published version of ASCE 24, Flood Resistant Design and Construction, published by the American Society of Civil Engineers.

“Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year. Also referred to as the “100-year flood.”

“Base flood elevation (BFE)” means the elevation to which floodwater is anticipated to rise during the base flood.

“Basement” means any area of the building having its floor sub-grade (below ground level) on all sides.

Building. See “Structure.”

“Building code” means the currently effective versions of the International Building Code and the International Residential Code adopted by the State of Washington Building Code Council.

“Critical facility” means a facility for which even a slight chance of flooding might be too great. Critical facilities include (but are not limited to) schools, nursing homes, hospitals, police, fire and emergency response installations, and installations which produce, use, or store hazardous materials or hazardous waste.

“Development” means any manmade change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations or storage of equipment or materials located within the area of special flood hazard.

“Development permit” means a generic term that includes any and all reviews, licenses, authorizations, approvals, permits, etc., that allow the city a right of review on proposals that ultimately result in a physical alteration to the environment.

“Elevated building” means, for insurance purposes, a nonbasement building that has its lowest elevated floor raised above ground level by foundation walls, shear walls, posts, piers, pilings, or columns.

“Elevation certificate” means an administrative tool of the National Flood Insurance Program (NFIP) that can be used to provide elevation information, to determine the proper insurance premium rate, and to support a request for a letter of map amendment (LOMA) or letter of map revision based on fill (LOMR-F).

Essential Facility. This term has the same meaning as “Essential Facility” defined in ASCE 24. Table 1-1 in ASCE 24-14 further identifies building occupancies that are essential facilities.

“Existing manufactured home park or subdivision” means a manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is completed before the effective date of the floodplain management regulations adopted by the community.

“Expansion to an existing manufactured home park or subdivision” means the preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads).

“Farmhouse” means a single-family dwelling located on a farm site where resulting agricultural products are not produced for the primary consumption or use by the occupants and the farm owner.

“Flood” or “flooding” means:

(1) A general and temporary condition of partial or complete inundation of normally dry land areas from:

(a) The overflow of inland or tidal waters; and/or

(b) The unusual and rapid accumulation of runoff of surface water from any source.

(c) Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in subsection (1)(b) of this definition and are akin to a river of liquid and flowing mud on the surfaces or normally dry land areas, as when earth is carried by a current of water and deposited along the path of the current.

(2) The collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding as defined in subsection (1)(a) of this definition.

“Flood elevation study” means an examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards. Also known as a flood insurance study (FIS).

“Flood insurance rate map (FIRM)” means the official map on which the Federal Insurance Administrator has delineated both the areas of special flood hazard areas and the risk premium zones applicable to the community. A FIRM that has been made available digitally is called a digital flood insurance rate map (DFIRM).

“Floodplain or flood-prone area” means any land area susceptible to being inundated by water from any source. See “Flood” or “flooding.”

“Floodplain administrator” means the community official designated by title to administer and enforce the floodplain management regulations.

“Floodplain management regulations” means zoning ordinances, subdivision regulations, building codes, health regulations, special purpose ordinances (such as floodplain ordinance, grading ordinance and erosion control ordinance) and other application of police power. The term describes such state or local regulations, in any combination thereof, which provide standards for the purpose of flood damage prevention and reduction.

“Floodproofing” means any combination of structural and nonstructural additions, changes, or adjustments to structures which reduce or eliminate risk of flood damage to real estate or improved real property, water and sanitary facilities, structures, and their contents. Floodproofed structures are those that have the structural integrity and design to be impervious to floodwater below the base flood elevation.

“Floodway” means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height. Also referred to as “Regulatory Floodway.”

“Functionally dependent use” means a use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, and does not include long-term storage or related manufacturing facilities.

“Highest adjacent grade” means the highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.

“Historic structure” means any structure that is:

(1) Listed individually in the National Register of Historic Places (a listing maintained by the Department of the Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;

(2) Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;

(3) Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or

(4) Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:

(a) By an approved state program as determined by the Secretary of the Interior; or

(b) Directly by the Secretary of the Interior in states without approved programs.

“Lowest floor” means the lowest floor of the lowest enclosed area (including basement). An unfinished or flood-resistant enclosure, usable solely for parking of vehicles, building access or storage, in an area other than a basement area is not considered a building’s lowest floor; provided, that such enclosure is not built so as to render the structure in violation of the applicable nonelevation design requirements of this chapter (provided there are adequate flood ventilation openings).

“Manufactured home” means a structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when connected to the required utilities. The term “manufactured home” does not include a “recreational vehicle.”

“Manufactured home park or subdivision” means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.

“Mean sea level” for purposes of the National Flood Insurance Program means the vertical datum to which base flood elevations shown on a community’s flood insurance rate map are referenced.

“New construction” means, for the purposes of determining insurance rates, structures for which the “start of construction” commenced on or after the effective date of an initial flood insurance rate map or after December 31, 1974, whichever is later, and includes any subsequent improvements to such structures. For floodplain management purposes, “new construction” means structures for which the “start of construction” commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures.

“New manufactured home park or subdivision” means a manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is completed on or after the effective date of adopted floodplain management regulations adopted by the community.

One-Hundred-Year Flood or 100-Year Flood. See “Base flood.”

“Reasonably safe from flooding” means development that is designed and built to be safe from flooding based on consideration of current flood elevation studies, historical data, high water marks and other reliable data known to the community. In unnumbered A zones where flood elevation information is not available and cannot be obtained by practicable means, “reasonably safe from flooding” means that the lowest floor is at least two feet above the highest adjacent grade.

“Recreational vehicle” means a vehicle:

(1) Built on a single chassis;

(2) Four hundred square feet or less when measured at the largest horizontal projection;

(3) Designed to be self-propelled or permanently towable by a light duty truck; and

(4) Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.

“Start of construction” includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement or other improvement was within 180 days of the permit date. The “actual start” means either the first placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the state of excavation; or the placement of a manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading, and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, foots, piers or foundation or the erection of temporary forms; nor does it include the installation on a property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure. For a substantial improvement, the “actual start of construction” means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building.

“Structure” means a walled and roofed building including a gas or liquid storage tank that is principally above ground, as well as a manufactured home.

“Substantial damage” means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.

“Substantial improvements” means any repair, reconstruction, addition, or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure before the “start of construction” of the improvement. This term includes structures which have incurred “substantial damage,” regardless of the actual repair work performed.

The term can exclude:

(1) Any project for improvement of a structure to correct pre-cited violations of state or local health, sanitary, or safety code specifications which have been previously identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions; or

(2) Any alteration of a “historic structure”; provided, that the alteration will not preclude the structure’s continued designation as a “historic structure.”

“Substantial damage” means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before-damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.

“Variance” means a grant of relief by a community from the terms of a floodplain management regulation.

“Water surface elevation” means the height, in relation to the vertical datum utilized in the applicable flood insurance study of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas.

“Water dependent” means a structure for commerce or industry that cannot exist in any other location and is dependent on the water by reason of the intrinsic nature of its operations. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 1)

Article II. General Provisions

2.05.020 Lands to which this chapter applies.

This chapter shall apply to all areas of special flood hazard within the jurisdiction of the city of Wenatchee. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 2.1)

2.05.030 Basis for establishing the areas of special flood hazard.

The areas of special flood hazard identified by the Federal Insurance Administrator in a scientific and engineering report entitled “The Flood Insurance Study for the City of Wenatchee, Chelan County, Washington” dated January 6, 1994, and any revisions thereto, with accompanying flood insurance rate map dated January 6, 1994, the subsequent letter of map amendment (LOMR) dated May 13, 1996, and any revisions thereto, are hereby adopted by reference and declared to be a part of this chapter. The flood insurance study and FIRM are on file at 1350 McKittrick Street. The best available information for flood hazard area identification as outlined in WCC 2.05.100(2) shall be the basis for regulation until a new FIRM is issued that incorporates data utilized under WCC 2.05.100(2). (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 2.2)

2.05.035 Compliance.

All development within special flood hazard areas is subject to the terms of this chapter and other applicable regulations. (Ord. 2021-28 § 1)

2.05.040 Penalties for noncompliance.

No structure or land shall hereafter be constructed, located, extended, converted, or altered without full compliance with the terms of this chapter and other applicable regulations. Violation of the provisions of this chapter by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions) shall constitute a code violation. Any person who violates this chapter or fails to comply with any of its requirements shall pay all costs and expenses involved in this case. Nothing herein contained shall prevent the city of Wenatchee from taking such other lawful action as is necessary to prevent or remedy violations. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 2.3)

2.05.050 Abrogation and greater restrictions.

This chapter is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this chapter and another ordinance, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 2.4)

2.05.060 Interpretation.

In the interpretation and application of this chapter, all provisions shall be:

(1) Considered as minimum requirements;

(2) Liberally construed in favor of the governing body; and

(3) Deemed neither to limit or repeal any other powers granted under state statute. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 2.5)

2.05.070 Warning and disclaimer of liability.

The degree of flood protection required by this chapter is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on rare occasions. Flood heights may be increased by manmade or natural causes. This chapter does not imply that land outside the areas of special flood hazards or uses permitted within such areas will be free from flooding and flood damages. This chapter shall not create liability on the part of the city of Wenatchee, any officer or employee thereof, for any flood damage that results from reliance on this chapter or any administrative decision lawfully made herein. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 2.6)

Article III. Administration

2.05.080 Establishment of development permit.

(1) Development Permit Required. A development permit shall be obtained before construction or development begins within an area of special flood hazard established in WCC 2.05.030. The permit shall be for all structures, including manufactured homes, as set forth in WCC 2.05.010, Definitions, and for all development including fill and other activities, also as set forth in WCC 2.05.010, Definitions.

(2) Application for Development Permit. Application for a development permit shall be made on forms furnished by the local administration and may include, but not be limited to: plans in duplicate drawn to scale showing the nature, location, dimensions and elevations of the area in question; existing or proposed structures, fill, storage of materials, drainage facilities, and the location of the foregoing. Specifically, the following information is required:

(a) Elevation, in relation to mean sea level, of the lowest floor (including basement) of all structures;

(b) Elevation in relation to mean sea level to which any structure has been floodproofed;

(c) In AO zones, elevation in relation to highest adjacent grade, of the lowest floor (including basement) of all structures;

(d) In AO zones, elevation in relation to highest adjacent grade to which any structure has been floodproofed.

(e) Certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet the floodproofing criteria in WCC 2.05.190; and

(f) Description of the extent to which a watercourse will be altered or relocated as a result of proposed development. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 3.1)

2.05.090 Designation of the floodplain administrator.

The planning director, building official, or their designee is hereby appointed to administer and implement this chapter by granting or denying development permit applications in accordance with its provisions. The floodplain administrator may delegate authority to implement these provisions. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 3.2)

2.05.100 Duties and responsibilities of the floodplain administrator.

Duties of the administrator shall include, but not be limited to:

(1) Permit Review.

(a) Review all development permits to determine that the permit requirements of this chapter have been satisfied.

(b) Review all development permits to determine that all necessary permits have been obtained from those federal, state and local governmental agencies from which prior approval is required.

(d) Review all development permits to determine that the proposed development is not located in the floodway. If located in the floodway, assure the encroachment provisions of WCC 2.05.250(1) are met.

(e) Notify FEMA when annexations occur in the special flood hazard area.

(f) Notify FEMA of changes to the base flood elevation within six months of when technical information of such changes becomes available. Such notification shall include technical or scientific information.

(2) Use of Other Base Flood Data. When base flood elevation data has not been provided in accordance with WCC 2.05.030, Basis for establishing the areas of special flood hazard, the floodplain administrator shall obtain, review and reasonably utilize any base flood elevation and floodway data available from a federal, state or other source, in order to administer WCC 2.05.170 through 2.05.230, Specific standards, and WCC 2.05.240, Standards for shallow flooding areas (AO zones).

(3) Information to Be Obtained and Maintained.

(a) Where base flood elevation data is provided through the flood insurance study, FIRM, or required as in subsection (2) of this section, obtain and maintain a record of the actual (as built) elevation (in relation to mean sea level) of the lowest floor (including basement) of all new or substantially improved structures, and whether or not the structure contains a basement.

(b) For all new or substantially improved floodproofed nonresidential structures where base flood elevation data is provided through FIS, FIRM, or as required in subsection (2) of this section:

(i) Obtain and maintain a record of the actual elevation in relation to mean sea level to which the structure was floodproofed; and

(ii) Maintain the floodproofing certifications required in WCC 2.05.080(2)(c).

(c) For AO zones, obtain and maintain a record of the actual (as-built) elevation of the lowest floor (including basement) above the highest adjacent grade of all new or substantially improved structures, and whether or not the structure contains a basement.

(d) For all new or substantially improved floodproofed nonresidential structures in AO zones:

(i) Obtain and maintain a record of the elevation above the highest adjacent grade to which the structure was floodproofed.

(ii) Maintain the floodproofing certifications required in WCC.2.05.080(2)(c).

(e) Maintain for public inspection all records pertaining to the provisions of this chapter.

(f) Certification required by WCC 2.05.250(1) (floodway encroachments).

(g) Records of all variance actions, including justification of their issuance.

(h) Improvement and damage calculations.

(4) Alteration of Watercourses.

(a) Notify adjacent communities and the Washington State Department of Ecology prior to any 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.

(5) Interpretation of FIRM Boundaries. Make interpretation where needed, as to exact location of the boundaries of the areas of special flood hazards (for example, 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 (44 CFR 59-76). (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 3.3)

Article IV. Provisions for Flood Hazard Reduction

2.05.110 General standards.

Repealed by Ord. 2021-28. (Ord. 2016-02 § 1; Ord. 2004-18 § 4.1)

2.05.120 Anchoring.

(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.

(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). (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.1-1)

2.05.130 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 designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.1-2)

2.05.135 Storage of materials and equipment.

(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. 2021-28 § 1)

2.05.140 Utilities.

(1) All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system. Water wells shall be located on high ground that is not in the floodway;

(2) 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

(3) On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.1-3)

2.05.150 Subdivision proposals and development.

(1) All subdivision proposals as well as new development shall be consistent with the need to minimize flood damage;

(2) All subdivision proposals as well as new development shall have public utilities and facilities such as sewer, gas, electric, and water systems located and constructed to minimize or eliminate flood damage;

(3) All subdivision proposals as well as new development 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 development which contain at least 50 lots or five acres (whichever is less). (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.1-4)

2.05.160 Review of building permits.

Where elevation data is not available either through the flood insurance study, FIRM, or from another authoritative source (WCC 2.05.100(2)), 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. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.1-5)

2.05.170 Specific standards.

In all areas of special flood hazards where base flood elevation data has been provided as set forth in WCC 2.05.030, Basis for establishing the areas of special flood hazard, or 2.05.100(2), Use of Other Base Flood Data, the provisions of WCC 2.05.180 through 2.05.230 are required. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.2)

2.05.180 Residential construction.

(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 base flood elevation. Mechanical equipment and utilities shall be waterproofed or elevated at least one foot above the BFE.

(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 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.

(d) A garage attached to a residential structure, constructed with the garage flood slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters.

(3) New construction and substantial improvement of any residential structure in an AO zone shall meet the requirements in WCC 2.05.240.

(4) 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. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.2-1)

2.05.190 Nonresidential construction.

New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall met 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 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 BFE, or as required by ASCE 24, whichever is greater;

(b) If located in an AO zone, the structure shall meet the requirements in WCC 2.05.240.

(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 floodwater.

(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 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 method of construction are in accordance with acceptable standards of practice for meeting provisions of this subsection based on their development and/or review of the structure design, specifications and plans. Such certifications shall be provided to the official as set forth in WCC 2.05.100(3)(b).

(d) Nonresidential structures that are elevated, not floodproofed, must meet the same standard for space below lowest floor as described in WCC 2.05.180(2).

(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 constructed to the base flood level will be rated as one foot below that level. Floodproofing the building an additional foot will reduce insurance premiums). (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.2-2)

2.05.200 Manufactured homes.

All manufactured homes to be placed or substantially improved within the floodplain 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 in accordance with the provisions of WCC 2.05.120(2). (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.2-3)

2.05.210 Recreational vehicles.

Recreational vehicles placed on sites are required to either:

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

(2) 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; or

(3) Meet the requirements of WCC 2.05.200 and the elevation and anchoring requirements for manufactured homes. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.2-3)

2.05.215 Enclosed area below the lowest floor.

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. 2021-28 § 1)

2.05.220 Crawlspaces.

Crawlspaces are commonly used as a method of elevating buildings in SFHAs to or above the BFE. General NFIP requirements that apply to all crawlspaces that have enclosed areas or floors below the BFE include the following:

(1) The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effect of buoyancy. Hydrostatic loads and the effects of buoyancy can usually be addressed through the required openings discussed below. Because of hydrostatic loads, crawlspace construction is not recommended in areas with flood velocities greater than five feet per second unless the design is reviewed by a qualified design professional, such as a registered architect or professional engineer.

(2) The crawlspace is an enclosed area below the BFE and, as such, must have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. The bottom of each flood vent opening can be no more than one foot above the lowest adjacent exterior grade. (For guidance on flood openings, see Technical Bulletin 1-93, Openings in Foundation Walls.)

(3) Portions of the building below the BFE must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawlspace used to elevate the building, but also any joists, insulation, or other materials that extend below the BFE. The recommended construction practice is to elevate the bottom of joists and all insulation above BFE.

(4) Any building utility systems within the crawlspace must be elevated above the BFE or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions. Duct work in particular must either be placed above the BFE or sealed from floodwaters.

(5) In addition to the above requirements, the following provisions apply to below-grade crawlspaces:

(a) The interior grade of a crawlspace below the BFE must not be more than two feet below the lowest adjacent exterior grade (LAG).

(b) The height of the below-grade crawlspace, measured from the interior grade of the crawlspace to the top of the crawlspace foundation wall, must not exceed four feet at any point.

(c) There must be an adequate drainage system that removes floodwaters from the interior area of the crawlspace. The enclosed area should be drained within a reasonable time after a flood event. Possible options include natural drainage through porous, well-drained soils and drainage systems such as perforated pipes, drainage tiles, or gravel or crushed stone drainage by gravity of mechanical means.

(d) The velocity of floodwaters at the site should not exceed five feet per second for any crawlspace.

(e) Below-grade crawlspace construction in accordance with the requirements listed above will not be considered basements.

(6) All crawlspace construction shall conform to FEMA Technical Bulletin 11-01, Crawlspace Construction for Buildings Located in Special Flood Hazard Areas. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2007-29 § 1; Ord. 2004-18 § 4.2-4)

2.05.230 AE and A1-30 zones with base flood elevations but no floodways.

In areas with base flood elevation, but no regulatory floodway has been designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within Zones A1-30 and AE on the community 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. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.2-4)

2.05.240 Standards for shallow flooding areas (AO zones).

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 these areas, the following provisions apply:

(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 grade adjacent to the building, one foot or more above the depth number specified on the 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 the 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 capacity 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 WCC 2.05.190(2).

(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 are required to either:

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

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

(c) Meet the requirements of subsections (1) and (3) of this section and the anchoring requirements for manufactured homes of WCC 2.05.120. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.3)

2.05.250 Floodways.

Located within areas of special flood hazard established in WCC 2.05.030 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:

(1) No Rise Standard. 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.

(2) Residential Construction in Floodways. 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, (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 which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions, or to structures identified as historic places, may be excluded in the 50 percent.

(3) All Other Building Standards Apply in the Floodway. If subsection (1) of this section is satisfied or construction is allowed pursuant to subsection (2) of this section, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this chapter. (Ord. 2021-28 § 1; Ord. 2016-02 § 1; Ord. 2004-18 § 4.4)

2.05.260 Critical facilities.

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. 2021-28 § 1)

Prior legislation: Ord. 2259.