Chapter 16.35
FREQUENTLY FLOODED AREAS
Sections:
16.35.010 Introduction.
A. Purpose. It is the purpose of this chapter to safeguard public health, safety and welfare by placing limitations on development in areas susceptible to flood waters consistent with the requirements of the Growth Management Act and Chapter 365-190 WAC.
B. Applicability. After the adoption of this chapter, no structure shall hereafter be constructed, substantially improved, located, extended, converted, or replaced, nor any land altered without full compliance with the terms of this chapter and other applicable regulations.
1. Frequently flooded areas may include lands outside of Federal Emergency Management Agency defined special flood hazard area floodplains and shall include:
a. Areas Identified on the Flood Insurance Map(s). Those areas of special flood hazard identified by the Federal Insurance Administration in a scientific and engineering report entitled “The Flood Insurance Study (FIS) for Clark County and Incorporated Areas,” dated January 19, 2018, with accompanying flood insurance rate maps (FIRM) and any revisions thereto. The flood insurance study and accompanying map(s) are hereby adopted by reference, declared part of this chapter, and are available for public review at the Clark County public works department.
b. Areas Identified by the Public Works Director. Those areas of special flood hazard identified by the public works director based on review of base flood elevation and floodway data available from federal, state, county, or other valid sources when base flood elevation data has not been provided from the Federal Insurance Administration (A and V zones of the flood insurance map(s)).
c. Use of Additional Information. The public works director may use additional flood information, such as provided by the Army Corps of Engineers, that is more restrictive or detailed than that provided in the flood insurance study conducted by the Federal Emergency Management Agency to designate frequently flooded areas. The flood insurance maps are to be used as a guide for the town, project applicants and/or property owners, and the public and should be considered a minimum designation of frequently flooded areas. As flood insurance maps may be continuously updated as areas are reexamined or new areas are identified, newer and more accurate information for flood hazard area identification shall be the basis for regulation, including photographs of past flooding, location of restrictive floodways, maps showing future build-out conditions, maps that show riparian habitat areas, or similar information.
2. This chapter is not intended to repeal or impair any existing easements, covenants or deed restrictions.
3. In the interpretation and application of this chapter, all provisions shall be:
a. Considered as minimum requirements;
b. Liberally construed to achieve the purposes of this chapter; and
c. Deemed neither to limit nor repeal any other powers granted under state statutes.
C. Definitions. For the purposes of this chapter and division, the following definitions shall apply:
“Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year and is also referred to as the “100-year flood.”
“Base flood elevation” means the height in relation to the North American Vertical Datum (NAVD)1988, expected to be reached by the waters of the base flood at pertinent points in the floodplains of coastal and riverine areas.
“Basement” means any area of the building having its floor subgrade below ground level on all sides.
“Critical facility” means the following:
1. Structures or facilities that produce, use or store highly volatile, flammable, explosive, toxic and/or water-reactive materials;
2. Hospitals, nursing homes, and housing likely to contain occupants who may not be sufficiently mobile to avoid death or injury during a flood;
3. Police stations, fire stations, vehicle and equipment storage facilities, and emergency operations centers that are needed for flood response activities before, during and after a flood; and
4. Public and private utility facilities that are vital to maintaining or restoring normal services to flooded areas before, during, and after a flood.
“Development” means, in addition to the definition in YMC 18.10.010, the storage of equipment and materials.
“Elevation certificate” means the official form (FEMA 81-31) used to record the elevation of a structure on a given property relative to the NAVD 1988.
“Encroachment” means the intrusion of any building, structure, vegetation, fill, excavation, or other development or use into a special flood hazard area which may impede or alter the flow through or storage capacity of a special flood hazard area.
“FEMA” means the Federal Emergency Management Agency.
“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 waters; and/or
2. The unusual and rapid accumulation of runoff of surface waters from any source.
“Flood insurance rate maps” (FIRMs) means the official maps on which the Federal Insurance Administration has delineated both the special flood hazard areas and the risk premium zones applicable to the county.
“Flood insurance study” means an official report published by FEMA in conjunction with the community’s flood insurance rate maps (FIRMs). The study contains such background data as the base flood discharges and water surface elevations that were used to prepare the FIRMs.
“Floodproofing” means any combination of structural and nonstructural additions, changes or adjustments to properties and structures which reduce or eliminate flood damages to lands, water and sanitary facilities, and structures and their contents.
“Floodway” means the channel of a river or other watercourse and 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.
“Lowest floor” means the lowest floor of the lowest enclosed area (including the basement). An unfinished or flood-resistant enclosure usable solely for parking of vehicles or for 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 YMC 16.35.020(B)(2).
“Special flood hazard area” or “floodplain” means any land area subject to a one percent or greater chance of flooding in any given year.
“Start of construction” means, in addition to the definition in YMC 18.10.010, for a substantial improvement, 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, in addition to the definition in YMC 18.10.010:
1. A gas or liquid storage tank that is principally above ground; and
2. 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 improvement” means any repair, reconstruction, or improvement of a structure, the cost of which is equal to or greater than 50 percent of the market value of the structure either:
1. Before the improvement or repair is started; or
2. If the structure has been damaged and is being restored, before the damage occurred.
“Substantial improvement” can exclude:
1. 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 identified by a code enforcement official and which are the minimum necessary to assure safe living conditions; or
2. Any alteration of a structure listed on the National Register of Historic Places or the Clark County heritage register.
D. Flood Insurance Study and Maps.
1. The special flood hazard areas identified by the Federal Emergency Management Agency (FEMA) in a report entitled “Flood Insurance Study, Clark County, Washington and Incorporated Areas” (FIS), effective January 19, 2018, and accompanying flood insurance rate maps (FIRMs) and any revisions thereto are hereby adopted by reference. The FIS and the FIRMs are on file with the Clark County public works department.
2. For the FIS and the FIRMs, the vertical datum was converted from the National Geodetic Vertical Datum of 1929 (NGVD29) to the North American Vertical Datum of 1988 (NAVD88). In addition, the transverse Mercator, state plane coordinates, previously referenced to the North American Datum of 1927 (NAD27), are now referenced to the North American Datum of 1983 (NAD83).
3. The best available information for special flood hazard area identification as outlined in this subsection D shall be the basis for regulation until new information is incorporated into the FIRMs.
E. Warning and Disclaimer of Liability. The degree of flood protection required by this chapter is considered reasonable for regulatory purposes, and is based upon 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 special flood hazard areas, 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 town of Yacolt, any officer or employee thereof, or the Federal Emergency Management Agency for any flood damages that result from reliance on this chapter or any administrative decision lawfully made hereunder. [Ord. 569 § 2 (Exh. A), 2018.]
16.35.020 Standards.
A. Uses.
1. Allowed Uses in Special Flood Hazard Areas.
a. Development may be allowed for those uses in an underlying zoning district with a flood hazard permit pursuant to YMC 16.35.030(C).
b. Park, recreational, agricultural, and other similar open space uses allowed in the underlying zoning district, which do not involve development as defined in this chapter, are permitted outright in special flood hazard areas.
2. Prohibited Uses in Special Flood Hazard Areas.
a. Construction or reconstruction of residential structures is prohibited in the floodway, except in accordance with Chapter 86.16 RCW for repairs, reconstruction, or improvements to a lawfully established structure:
i. Which do not increase the ground floor area; and
ii. That are not substantial improvements.
b. Floodway encroachments are prohibited unless certification by an engineer as defined in YMC 16.20.260 is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge. If it has been adequately demonstrated through calculations that the encroachment will not result in increased flood levels, all new nonresidential construction and nonresidential substantial improvements shall comply with all applicable flood hazard reduction provisions of this chapter.
3. Special Flood Hazard Area with Base Flood Elevation but No Floodways. In areas with base flood elevation but where a regulatory floodway has not been designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within zone AE, 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 in the town.
B. General Construction Standards.
1. In all special flood hazard areas, the following standards are required:
a. Anchoring, in accordance with FEMA requirements.
i. All new construction and any substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.
ii. 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, and additional techniques referenced in the current FEMA’s guidebook FEMA P-85, Protecting Manufactured Homes from Floods and Other Hazards.
b. Construction Materials and Methods, in accordance with FEMA Technical Bulletin 2.
i. All new construction and any substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
ii. All new construction and any substantial improvements shall be constructed using methods and practices that minimize flood damage.
iii. Electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities shall be designed, elevated or located so as to prevent water from entering or accumulating within the components during flooding.
c. Utilities.
i. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.
ii. 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.
iii. On-site waste disposal systems shall be located or designed to avoid impairment to them or contamination from them during flooding.
iv. Water wells shall not be located in the floodway or areas subject to ponding.
d. Subdivision proposals shall:
i. Identify lots and portions of lots in special flood hazard areas as part of preliminary plat submittal;
ii. Be designed to minimize flood damage;
iii. Have any public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage;
iv. Have adequate drainage provided to reduce exposure to flood damage;
v. Have roadways designed such that, in the event of a 100-year flood, one travel lane in either direction shall not be covered by more than six inches of water; and
vi. Have adequate drainage provided to reduce exposure to flood damage.
2. Specific Construction Standards. In all special flood hazard areas the following construction standards are required:
a. Residential Construction.
i. New residential construction and substantial improvement of any residential structure shall have the lowest floor, including the basement, elevated to at least one foot above base flood elevation.
ii. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, unless 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 licensed engineer as defined in YMC 16.20.260 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; and
(C) Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.
iii. Below-Grade Crawl Spaces.
(A) Below-grade crawl spaces will not be considered basements if constructed to the following criteria:
(1) The interior grade of the crawl space is not more than two feet below the lowest adjacent exterior grade.
(2) The height of the below-grade crawl space, measured from the interior grade of the crawl space to the top of the crawl space foundation wall, must not exceed four feet at any point. The height limitation is the maximum allowable unsupported wall height according to the engineering analyses and building code requirements for flood hazard areas.
(3) There must be an adequate drainage system that removes floodwaters from the interior area of the crawl space.
(4) The velocity of floodwaters at the site should not exceed five feet per second for any crawl space. For velocities in excess of five feet per second, other foundation types should be used.
(5) Utility systems within the crawl space, particularly ductwork, must be elevated above the base flood elevation, or designed so that floodwaters cannot enter or accumulate within system components, or be damaged during flood conditions.
(6) All insulation must be located above the base flood elevation.
(B) Buildings that have below-grade crawl spaces may have higher flood insurance premiums than buildings that have the preferred crawl space construction with the interior elevation at or above the lowest adjacent grade.
(C) For additional information and diagrams see FEMA Technical Bulletin 11.
b. Nonresidential Construction.
i. New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall either have the lowest floor, including the basement, elevated to at least one foot above base flood elevation; or together with attendant utility facilities, shall:
(A) Be floodproofed so that the structure is watertight with walls substantially impermeable to the passage of water up to one foot above the base flood elevation;
(B) Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
(C) Be certified by a licensed engineer as defined in YMC 16.20.260 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 on FEMA Form 81-65 and provided to the responsible official;
ii. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subsection (B)(2)(a)(ii) of this section; and
iii. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates for floodproofing to 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).
c. Manufactured Homes. All manufactured homes to be placed or substantially improved within a special flood hazard area shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at least one foot above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement in accordance with the provisions of subsection (B)(1)(a)(ii) of this section.
d. Travel Trailers and Recreational Vehicles. Travel trailers and recreational vehicles are allowed as follows:
i. In the floodway on a seasonal basis between May 1st and October 1st of the same year and within the floodway fringe areas on a temporary basis for fewer than 180 consecutive days.
ii. Vehicle remains fully licensed or has a valid trip permit from the Washington State Department of Licensing 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.
e. Critical Facilities.
i. New critical facilities shall be outside of special flood hazard areas unless no feasible alternative site is available.
ii. Critical facilities constructed within the special flood hazard areas shall have:
(A) The lowest floor elevated three feet above the base flood elevation or to the height of 500-year flood, whichever is higher;
(B) Access to and from the critical facility should be protected to the height utilized above; and
(C) Floodproofing and sealing measures to ensure that toxic substances will not be displaced by or released into floodwaters.
3. Floodways. Areas designated as floodways are located within special flood hazard areas established in YMC 16.35.010. 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. There is a prohibition on 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 encroachments shall not result in any increased flood levels during the occurrence of the base flood discharge.
b. If it has been adequately demonstrated that the encroachment will not result in increased flood levels, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section. [Ord. 569 § 2 (Exh. A), 2018.]
16.35.030 Administration.
A. Establishment of Floodplain Review. The public works director or his/her designee is the responsible official for purposes of administering this chapter. A review shall be obtained before construction or development begins within any special flood hazard areas established in this chapter.
B. Flood Hazard Inquiry.
1. Floodplain review application forms shall be furnished by the responsible official.
2. The responsible official shall review the application and other pertinent information, and make a determination as to whether the proposed development is in a special flood hazard area and whether a flood hazard permit is required. The responsible official shall inform the applicant in writing whether or not a permit is required. The public works director shall render a decision on the proposal within 30 days after receiving the application unless additional information is needed from the applicant, in which case a decision shall be made within 30 days after receiving the information necessary to complete the review.
C. Flood Hazard Permit.
1. A flood hazard permit must be obtained before construction or development begins within any special flood hazard area. The review shall be for all structures and development as defined in YMC 18.10.010 and this chapter.
2. For land divisions, a flood hazard permit will be issued as part of the land division review process. The following information is required:
a. Floodplain and floodway limits;
b. Finished grading;
c. Building envelopes; and
d. Hydrologic and hydraulic calculations used to determine the impact of the proposed development on base flood elevation. Where base flood elevation data is not available from the flood insurance study, FIRMs, or from another authoritative source, it shall be provided by the applicant for subdivisions and other proposed development which contain at least 50 lots or five acres, whichever is less. This documentation shall be prepared by an engineer as defined in YMC 16.20.260.
3. For building permits, a flood hazard review will be done as part of the building permit review process. The following information is required:
a. Floodplain and floodway limits;
b. Finished grading;
c. Building envelopes; and
d. Hydrologic and hydraulic calculations used to determine the impact of the proposed development on base flood elevation. Where base flood elevation data is not available from the flood insurance study, FIRMs, or from another authoritative source, the applicant shall assure that proposed construction will be reasonably safe from flooding. The test of reasonableness shall be a judgment of the responsible official who shall consider historical data, high water marks, and photographs of past flooding, where available. This documentation shall be prepared by a licensed professional engineer registered in the state of Washington. Failure to elevate the lowest floor at least two feet above the highest adjacent grade in these zones may result in higher insurance rates.
4. Application for a flood hazard permit shall be made to the responsible official on a form furnished by the responsible official.
5. The application shall include, but not be limited to, plans in duplicate drawn to scale showing the nature, location, dimensions, and elevations of the area in question, and existing or proposed structures, fill, storage of materials, and drainage facilities. Specifically, the following information is required:
a. Elevation, in relation to mean sea level as determined by the National Geodetic Vertical Datum (NGVD) of 1988, of the lowest floor (including basement) of all structures;
b. Elevation, in relation to NGVD of 1988, to which any structure has been floodproofed;
c. Certification by a licensed engineer, as defined in YMC 16.20.260, that the floodproofing methods for any nonresidential structure meet the floodproofing criteria in YMC 16.35.020(B)(2)(b);
d. Description of the extent to which any watercourse will be altered or relocated as a result of the proposed development; and
e. Hydrologic and hydraulic calculations used to determine the impact of the proposed development on base flood elevation. If hydraulic modeling software is utilized for these calculations, all electronic files shall be submitted prior to flood hazard permit approval.
6. Responsibilities of the Responsible Official. The responsible official will:
a. Review all proposed developments with respect to the flood insurance study and accompanying maps and zoning district boundaries;
b. Make interpretations where needed as to the exact location of special flood hazard area boundaries;
c. When base flood elevation data has not been provided in accordance with this subsection C shall obtain, review and reasonably utilize any base flood elevation and floodway data available from an agency of federal or state government, or other sources, in order to enforce the provisions of this chapter;
d. Review all proposals to determine that the requirements of this chapter have been satisfied;
e. Review all proposals to determine that all necessary permits have been obtained from those federal, state or local governmental agencies from which prior approval is required; and
f. Issue a flood hazard permit with any conditions necessary to ensure that the development meets the requirements of this chapter.
7. Elevation Certificates Required. Elevation certificates are required to verify elevations of structures and aboveground equipment, and shall be submitted prior to receiving an inspection for footing, framing and certificate of occupancy. Elevation certificates shall be prepared by a licensed professional surveyor registered in the state of Washington.
D. Variances.
1. Generally, variances may be issued for new construction and substantial improvements to be erected on a lot of one-half acre or less in size, abutting and surrounded by lots with existing structures constructed below the base flood level, provided items in subsection (E)(1) of this section have been fully considered. As the lot size increases beyond the one-half acre, the technical justification required for issuing the variance increases.
2. 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, without regard to the procedures set forth in the remainder of this chapter.
3. Variances may be granted pursuant to the National Flood Insurance Program and applicable state law, and shall only be issued if the following are met:
a. The proposal has been designed to reasonably minimize the impact on the floodplain and its functions;
b. No increase in flood levels during the base flood discharge would result;
c. The variance is the minimum necessary, considering the flood hazard, to afford relief;
d. Failure to grant the variance would result in exceptional hardship to the applicant;
e. The hardship is not created by the property owner or its immediate predecessor in the title; and
f. The granting of a variance will not result in increased flood heights, additional threats to public safety, or extraordinary public expense, create nuisances, cause fraud on or victimization of the public.
4. 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 the flood elevations should be quite rare.
5. 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 and otherwise complies with YMC 16.35.020(B)(2)(b).
6. 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 significantly increased risk resulting from the reduced lowest floor elevation.
7. Variances may be issued for new construction and substantial improvements to be erected on a lot that is one-half acre or less in size, abutting and surrounded by lots with existing structures constructed below the base flood level; provided, that the items in this section have been fully considered.
8. The public works director shall report any variances to the Federal Emergency Management Agency upon request.
E. Appeals. Administrative decisions rendered by the responsible official or the public works director are subject to appeal according to the town of Yacolt appeals process.
1. In acting on appeals, the hearings examiner shall consider all technical evaluations, all relevant factors, and standards specified in other sections of this chapter, as well as:
a. The danger that materials may be swept onto other lands to the injury of others;
b. The danger to life and property due to flooding or erosion damage;
c. The susceptibility of the proposed facility and its contents to flood damage, and the effect of such damage on the individual owner;
d. The importance of the services provided by the proposed facility to the community;
e. The necessity to the facility of a waterfront location, where applicable;
f. The availability of alternative locations for the proposed use, which are not subject to flooding or erosion damage;
g. The compatibility of the proposed use with existing and anticipated development;
h. The relationship of the proposed use to the comprehensive plan and floodplain management program for that area;
i. The safety of access to the property in times of flood for ordinary and emergency vehicles;
j. 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; and
k. 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.
2. Upon consideration of the factors of subsection (E)(1) of this section and the purposes of this chapter, the hearings examiner may attach such conditions to actions on appeals as it deems necessary to further the purpose of this chapter.
3. The responsible official shall obtain and/or maintain the following:
a. Where base flood elevation data is provided through the flood insurance study, FIRMs, or as required in this section, obtain and record the actual elevation (in relation to mean sea level based on the NAVD 1988) of the lowest floor (including the 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, verify and record the actual elevation (in relation to mean sea level based on the NAVD 1988) to which the structure was floodproofed, and maintain the floodproofing certifications required in subsection (C)(5)(c) of this section.
c. All records for public inspection pertaining to the provisions of this chapter. [Ord. 569 § 2 (Exh. A), 2018.]