Chapter 18.16
FLOOD DAMAGE PREVENTION

Sections:

18.16.010    Findings of fact – Purpose.

18.16.020    Methods of reducing flood losses.

18.16.030    Definitions.

18.16.040    General provisions.

18.16.050    Administration.

18.16.060    General standards for flood hazard reduction.

18.16.070    Specific standards for flood hazard reduction.

18.16.080    Floodways.

18.16.090    Critical facilities.

18.16.010 Findings of fact – Purpose.

A. The flood hazard areas of the city are subject to periodic inundation, which results in loss of life and property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood protection and relief, and impairment of the tax base, all of which adversely affect the public health, safety and general welfare.

B. These flood losses are caused by the cumulative effect of obstructions in areas of special flood hazard which increase flood heights and velocities, and when inadequately anchored, damage uses in other areas. Uses that are inadequately floodproofed, elevated, or otherwise protected from flood damage also contribute to the flood loss.

C. It is the purpose of this chapter to promote the public health, safety and general welfare, and to minimize public and private losses due to flood conditions in specific areas by provisions designed:

1. To protect human life and health.

2. To minimize expenditure of public money for costly flood control projects.

3. To minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public.

4. To minimize prolonged business interruptions.

5. To minimize damage to public facilities and utilities such as water and gas mains, electric, telephone and sewer lines, streets and bridges located in areas of special flood hazard.

6. To help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard to minimize future flood blight areas.

7. To ensure that potential buyers are notified that property is in an area of special flood hazard.

8. To ensure that those who occupy the areas of special flood hazard assume responsibility for their actions.

9. To maintain community eligibility in the national flood insurance program. [Ord. 7-17 § 1, 2017; Ord. 432 § 1, 1981].

18.16.020 Methods of reducing flood losses.

In order to accomplish its purposes, this chapter includes methods and provisions for:

A. Restricting and prohibiting uses which are dangerous to health, safety and property due to water or erosion hazards, or which result in damaging increases in erosion or in flood heights or velocities.

B. Requiring that uses vulnerable to floods, including facilities which serve such uses, be protected against flood damage at the time of initial construction.

C. Controlling the alteration of natural floodplains, stream channels, and natural protective barriers, which help accommodate or channel floodwaters.

D. Controlling filling, grading, dredging, and other development which may increase flood damage.

E. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or which may increase flood hazards in other areas. [Ord. 7-17 § 1, 2017; Ord. 432 § 1, 1981].

18.16.030 Definitions.

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.

“Appeal” means a request for review of the community development director’s interpretation of any provision of this chapter or a request for a variance.

“Area of shallow flooding” means a designated AO or AH Zone on the flood insurance rate map (FIRM). The base flood depths 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.

“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. Designation on maps always includes the letters A or V.

“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”). Designated on flood insurance rate maps by the letters A or V.

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

“Breakaway wall” means a wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces, without causing damage to the elevated portion of the building or supporting foundation system.

“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.

“Cumulative substantial damage” means flood-related damage sustained by a structure on two separate occasions during a 10-year period for which the cost of repairs at the time of each such flood event, on the average, equals or exceeds 25 percent of the market value of the structure before the damage occurred.

“Designated floodway” means the regulatory floodway which has been delineated on the flood insurance rate map (FIRM) or the flood boundary/floodway map (FBFM) of a community’s flood insurance study.

“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.

“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 the official form (FEMA Form 81-31) used to track development, provide elevation information necessary to ensure compliance with community floodplain management ordinances, and determine the proper insurance premium rate with Section B completed by community officials.

“Existing mobile/manufactured home park” or “mobile/manufactured home subdivision” means a mobile home park or subdivision for which the construction of facilities for servicing the spaces/lots on which the mobile/manufactured home is to be affixed (including at a minimum the installation of utilities, either final site grading or the pouring of concrete pads, and the construction of streets) is completed before May 23, 1981, the effective date of the ordinance codified in this chapter.

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

“Flood” or “flooding” means a general and temporary condition of partial or complete inundation of normally dry land areas from:

1. The overflow of inland or tidal water; and/or

2. Unusual and rapid accumulation or runoff of surface waters from any source.

“Flood insurance rate map (FIRM)” means the official map on which the Federal Insurance Administration has delineated both the areas of special flood hazard and the risk premium zones applicable to the community.

“Flood insurance study” means the official report provided in which the Federal Insurance Administration has provided flood profiles, as well as the flood boundary-floodway map and the water surface elevation of the base flood.

“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 one foot.

“Habitable floor” means any floor usable for living purposes, which include working, sleeping, eating, cooking or recreation, or a combination thereof. A floor used only for storage purposes is not a habitable floor.

“Increased cost of compliance” means a flood insurance claim payment up to $30,000 directly to a property owner for the cost to comply with floodplain management regulations after a direct physical loss caused by a flood. Eligibility for an ICC claim can be through a single instance of substantial damage or as a result of cumulative substantial damage.

“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 found at WRMC 18.16.070(A)(2), (i.e., provided there are adequate flood ventilation openings).

“Mobile home” or “manufactured home” means a structure that is transportable in one or more sections, built on a permanent chassis, and designed to be used with or without a permanent foundation when connected to the required utilities. It does not include recreational vehicles, recreational park trailers, or travel trailers. Furthermore, a manufactured home is a single-family dwelling built according to the Department of Housing and Urban Development Manufactured Home Construction and Safety Standards Act. A mobile home is a factory-built dwelling built prior to June 15, 1976, to standards other than the HUD Code, and acceptable under applicable state codes in effect at the time of construction or introduction of the home into the state.

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

“New construction” means structures for which the start of construction commenced on or after May 23, 1981, the effective date of the ordinance codified in this chapter.

“New mobile/manufactured home park or mobile/manufactured home subdivision” means a mobile/manufactured home park or subdivision for which the construction of facilities for servicing the space or lot (including, at a minimum, the installation of utilities, either final site grading or the pouring of concrete pads, and the construction of streets) is completed on or after May 23, 1981, the effective date of the ordinance codified in this chapter.

“Person” means an individual, partnership, corporation, association, organization, cooperative, public or municipal corporation, or any agency of the state or local governmental unit however designated.

“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.

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, 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 stage 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, footings, piers, or foundations or the erection of temporary forms; nor does it include the installation on the 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 and a gas or liquid storage tank that is principally aboveground.

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

“Substantial improvement” means any repair, reconstruction or improvement of a structure when cost equals/exceeds 50 percent of the market value of the structure, either:

1. Before the improvement or repair is started.

2. If the structure has been damaged and is being restored, before the damage occurred. For the purposes of this definition, “substantial improvement” is considered to occur when the first alteration of any wall, ceiling, floor or other structural part of the building commences, whether or not that alteration affects the external dimensions of the structure.

3. This term can exclude:

a. Any project for improvement of a structure to correct pre-cited existing 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.

b. Any alteration of a structure listed on the National Register of Historic Places or State Inventory of Historic Places that does not expand the footprint of the structure. Reconstruction, rehabilitation or restoration of structures listed on the National Register of Historic Places or the State Inventory of Historic Places that would expand the footprint of the structure may be considered under the variance provisions of this chapter.

“Variance” means a grant of relief from the requirements of this chapter which permits construction in a manner that would otherwise be prohibited by this chapter.

“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. 7-17 § 1, 2017; Ord. 36-06 § 1, 2006; Ord. 432 § 1, 1981].

18.16.040 General provisions.

A. Lands to Which This Chapter Applies. This chapter applies to all areas of special flood hazard within city’s jurisdiction and as an overlay zone shall impose requirements on such areas in addition to those of zoning districts in which such areas are located.

B. Basis for Establishing the Areas of Special Flood Hazard. The areas of special flood hazard identified by the Federal Insurance Administration in a scientific and engineering report entitled “Flood Insurance Study – City of West Richland, Washington,” dated March 30, 1981, and any revisions thereto, with an accompanying flood insurance rate map and flood boundary-floodway map, and any revisions thereto, is hereby adopted by reference and declared to be a part of this chapter. The study and maps are on file in the community development department. For areas within Benton County which are annexed to the city, studies and maps prepared by the Federal Insurance Administration for Benton County shall be utilized to regulate development within any such identified flood hazard areas.

C. Penalty for Noncompliance. No structure or land shall, after the effective date of the ordinance codified in this chapter, be constructed, located, extended, converted, or altered without full compliance with the terms of this chapter and other applicable regulations. Violations 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 misdemeanor as set forth by Chapter 1.16 WRMC. Nothing herein contained shall prevent the city of West Richland from taking such other lawful action as is necessary to prevent or remedy any violation.

D. 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 chapter, easement, covenant or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.

E. 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 city.

3. Deemed neither to limit nor repeal any other powers granted under state statutes.

F. 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 hazard or uses permitted within such areas will be free from flooding or flood damages. This chapter shall not create liability on the part of the city of West Richland, any officer or employee thereof, or the Federal Insurance Administration, for any flood damages that result from reliance on this chapter or any administrative decision lawfully made thereunder. [Ord. 7-17 § 1, 2017; Ord. 36-06 § 1, 2006; Ord. 432 § 1, 1981].

18.16.050 Administration.

A. Establishment of a Flood Hazard Development Permit.

1. Development Permit Required. A flood hazard development permit shall be obtained before construction or development begins within any area of special flood hazard established in WRMC 18.16.040(B). The development permit shall be for all structures, including mobile/manufactured homes, as set forth in WRMC 18.16.030, Definitions, and for all other development, including fill and other activities, also as set forth in the definitions. A development shall be denied, approved or conditionally approved in accordance with the standards of this chapter and may be processed in conjunction with other city development applications (e.g., site plan approval permit, conditional use permit, or planned development permit).

2. Application for a flood hazard development permit shall be made on forms furnished by the community development department and be accompanied by a filing fee set by the city council. The application shall include all information required for any other development application with which it may be filed and include but not be limited to two full-size copies of the site plan, construction drawings and elevations, plus a reproducible site plan no larger than 11 inches by 17 inches. The site plan shall be drawn to scale and show the nature, location, dimensions, and elevations of the property and area in question, existing and proposed structures, fences or walls, fill or grading, storage of materials, drainage facilities, and any other information deemed necessary by the city to determine compliance with this chapter. Specifically, the following specific information is required:

a. Elevation, in relation to mean sea level, of the lowest floor (including basement) of all structures; recorded on a current elevation certificate (FF 81-31) with Section B completed by the local official.

b. Elevation in relation to mean sea level to which any structure has been floodproofed.

c. Certification by a registered professional engineer in the state that the floodproofing methods for any nonresidential structure meet the floodproofing criteria in WRMC 18.16.070.

d. A description of the extent to which any watercourse will be altered or relocated as a result of proposed development.

B. Designation of the Local Administrator. The community development director or designee shall administer and implement this chapter by granting or denying development permit applications in accordance with provisions of this chapter. The director may require substantiation that conditions of approval and standards of this chapter have been met and required certifications provided and, if not forthcoming, may revoke the development permit and require that development discontinue, the structure be vacated, and violations be corrected at property owner’s expense. When the first floor of a residential structure is required to be elevated as provided in WRMC 18.16.070, the director shall require that applicant submit a statement from a professional surveyor indicating elevation to which first floor was actually constructed.

C. Duties and Responsibilities of the Director. Duties of the community development director or his/her designee shall include, but not be limited to:

1. Permit Review.

a. Review all developments to determine if the development proposed is in the floodway; if located in the floodway, assure that the encroachment provisions of WRMC 18.16.080 are met.

b. Review all developments to determine that the permit requirements of this chapter have been satisfied.

c. Review all development permits to determine that all necessary permits have been obtained from those federal, state or local agencies from which prior approval is required.

2. Use of Other Base Flood Data. When base flood elevation data has not been provided in accordance with WRMC 18.16.040(B), Basis for Establishing the Areas of Special Flood Hazard, the director shall obtain, review, and reasonably utilize any base flood elevation data available from a federal, state or other source, in order to administer WRMC 18.16.070 and 18.16.080.

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 (C)(2) of this section, obtain and record the actual (as-built) elevation (in relation to mean sea level) of the lowest habitable floor (including basement) of all new or substantially improved structures, and whether or not the structure contains a basement; recorded on a current elevation certificate (FF 81-31) with Section B completed by the local official.

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

i. Obtain and record the elevation (in relation to mean sea level) to which the structure was floodproofed.

ii. Maintain the floodproofing certifications required in subsection (A)(2)(c) of this section.

c. Maintain for public inspection all records pertaining to the provisions of this chapter.

4. Alteration of Watercourses.

a. Notify adjacent communities and the Department of Ecology prior to any alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administration.

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 interpretations where needed, as to the exact location of the boundaries of the areas of special flood hazard (for example, where there appears to be a conflict between a mapped boundary and the actual field conditions).

D. Variance Procedure.

1. Board of Adjustment.

a. The board of adjustment shall hear and decide requests for variances from the requirements of this chapter.

b. The city council shall hear and decide appeals when it is alleged there is an error in any requirement, decision or determination made by the director in the enforcement or administration of this chapter.

c. Those aggrieved by the decision of the board of adjustment on a variance application may appeal such decision to the city council. The decision of the city council is final unless, within 20 days from the date of the action, an aggrieved party or persons obtains a writ of certiorari from the superior court in and for Benton County, for the purpose of review of the action taken.

d. In reviewing variance applications, the board of adjustment shall consider all technical evaluations, relevant factors, and standards specified in this chapter, and:

i. The danger that materials may be swept onto other lands to the injury of others.

ii. The danger to life and property due to flooding or erosion damage.

iii. The susceptibility of proposed facility and its contents to flood damage and the effect of such damage on the individual owner.

iv. The importance of the services provided by the proposed facility to the community.

v. The necessity to the facility of a waterfront location, where applicable.

vi. The availability of alternative locations for the proposed use which are not subject to flooding or erosion damage.

vii. The compatibility of the proposed use with existing and proposed development.

viii. The relationship of the proposed use to the comprehensive plan and floodplain management program of that area.

ix. The safety of access to the property in times of flood for ordinary and emergency vehicles.

x. The expected heights, velocity, duration, rate of rise, and sediment transport of the floodwaters, and the effects of wave action, if applicable, expected at the site.

xi. The costs of providing governmental services during and after flood conditions, including maintenance and repair of public utilities and facilities such as sewer, gas, electrical and water systems, and streets and bridges.

e. Upon consideration of these factors and the purposes of this chapter, the board of adjustment may approve, deny, or attach conditions to the granting of variances as deemed necessary to further the purposes of this chapter.

f. The city shall maintain records of all appeal actions, including technical information, and report variances to the Federal Insurance Administration upon request.

2. Conditions for Variances.

a. Generally, the only condition under which a variance from the elevation standard may be issued is for new construction and substantial improvements to be erected on an existing small (one-half acre or less) lot contiguous to and surrounded by lots with existing structures constructed below the base flood level, providing the factors in this subsection D have been fully considered. As lot size increases beyond one-half acre, technical justification required for issuing a variance increases.

b. Variances may be issued for the reconstruction, rehabilitation or restoration of structures listed on the National Register of Historic Places or the State Inventory of Historic Places. If the improvements to the historic structure do not expand the footprint of the structure, they can be exempted from the definition of “substantial improvement” and the variance procedure (see definition of “substantial improvement”).

c. Variances shall not be issued within any designated floodway if any increase in flood levels during the base flood discharge would result.

d. Variances shall only be issued upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.

e. Variances shall only be issued upon:

i. A showing of good and sufficient cause.

ii. A determination that failure to grant the variance would result in exceptional hardship to the applicant.

iii. A determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public as identified in subsection (D)(1)(d) of this section, or conflict with existing local laws or ordinances.

f. Variances as interpreted in the national flood insurance program are based on the general zoning law principle that they pertain to a physical piece of property; they are not personal in nature and do not pertain to the structure, its inhabitants, economic or financial circumstances. They primarily address small lots in densely populated residential neighborhoods. As such, variances from flood elevations should be quite rare.

g. Variances may be issued for nonresidential buildings in very limited circumstances to allow a lesser degree of floodproofing than watertight or dry-floodproofing, where it can be determined that such action will have low damage potential, complies with all other variance criteria, and otherwise complies with WRMC 18.16.060(A), (C) and (D) (general standards).

h. Any applicant to whom a variance is granted shall be given written notice that the structure will be permitted to be built with a lowest floor elevation below the base flood elevation and that the cost of flood insurance will be commensurate with the increased risk resulting from the reduced lowest floor elevation. [Ord. 7-17 § 1, 2017; Ord. 36-06 § 1, 2006; Ord. 432 § 1, 1981].

18.16.060 General standards for flood hazard reduction.

In all areas of special flood hazard the following general 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 mobile/manufactured homes shall be anchored to resist flotation, collapse, or lateral movement by providing over-the-top and frame ties to ground anchors. Special requirements shall be that:

a. Over-the-top ties shall be provided at each of the four corners of the mobile/manufactured home, with two additional ties per side at intermediate locations, with mobile/manufactured homes less than 50 feet long requiring only one additional tie per side;

b. Frame ties shall be provided at each corner of the home with five additional ties per side at intermediate points, with mobile homes less than 50 feet long requiring four additional ties per side;

c. All components of the anchoring system shall be capable of carrying a force of 4,800 pounds; and

d. Any additions to the mobile/manufactured home shall be similarly anchored.

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 designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding. Locating such equipment below the base flood elevation may cause annual flood insurance premiums to be increased.

C. Utilities.

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

2. Water wells shall be located on high ground that is not in the floodway;

3. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters; 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 development which contain at least 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, FIRM, or from another authoritative source (WRMC 18.16.050(C)(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 the highest adjacent grade in these zones may result in higher insurance rates. [Ord. 7-17 § 1, 2017; Ord. 36-06 § 1, 2006; Ord. 432 § 1, 1981].

18.16.070 Specific standards for flood hazard reduction.

In all areas of special flood hazard where base flood elevation data have been provided as set forth in WRMC 18.16.040(B), Basis for Establishing the Areas of Special Flood Hazard, or in WRMC 18.16.050(C)(2), Use of Other Base Flood Data, the following standards are required:

A. Residential Construction.

1. New construction and substantial improvement of any residential structure, including mobile and manufactured homes, shall have the lowest floor, including the basement, elevated to at least one foot 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. (Note: Foundation vent standards required by the IBC/IRC outside the floodplain do not meet this standard.)

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 to one foot 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 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 WRMC 18.16.050(C)(3).

4. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subsection (A)(2) of this section.

C. Manufactured/Mobile Homes.

1. All manufactured homes and mobile homes in the floodplain to be placed or substantially improved on sites shall be elevated on a permanent foundation such that the lowest floor of the manufactured/mobile 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.

D. Recreational vehicles, park trailers or travel trailers placed on sites are required to:

1. Be on the site for fewer than 180 consecutive days; and

2. Be fully licensed and ready for highway use, on wheels or jacking system, attached to site only by quick disconnect type utilities and security devices, and have no permanently attached additions. [Ord. 7-17 § 1, 2017; Ord. 36-06 § 1, 2006; Ord. 432 § 1, 1981].

18.16.080 Floodways.

Located within areas of special flood hazard established in WRMC 18.16.040(B) are areas designated as floodways. Since the floodway is an extremely hazardous area, due to the velocity of floodwaters 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 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.

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 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 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.

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 WRMC 18.16.060 through 18.16.090. [Ord. 7-17 § 1, 2017; Ord. 36-06 § 1, 2006; Ord. 432 § 1, 1981].

18.16.090 Critical facilities.

Construction of new critical facilities shall be, to the extent possible, located outside the limits of the special flood hazard area (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. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters. The director may also require access routes to be elevated one foot above the base flood elevation, where vehicle access to the critical facility would likely be needed during a flood event. The construction or filling for such access roads is subject to the standards of this chapter. [Ord. 7-17 § 1, 2017; Ord. 36-06 § 1, 2006].