Chapter 15.36 FLOODPLAIN MANAGEMENT STANDARDS

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:

A. To protect human life and health;

B. To minimize expenditures of public money and costly flood-control projects;

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

D. To minimize prolonged business interruption;

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

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

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

H. To ensure that those who occupy the areas of special flood hazard assume responsibility for their actions. (Ord. 2146 § 1, 1984).

15.36.020 Contents – Methods of reducing flood losses.

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

A. Restricting or 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; and

E. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters, or which may increase flood hazards in other areas. (Ord. 2146 § 2, 1984).

Article II. Definitions

15.36.030 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:

A. “Appeal” means a request for a review of the building official or his designee’s interpretation of any provision of this chapter, or a request for a variance.

B. “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. AO is characterized as sheet flow and AH indicates ponding.

C. “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, as established by FEMA. Designation on maps always includes the letters A or V.

D. “Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year, as established by FEMA; also referred to as the 100-year flood. Designation on maps always includes the letters A or V.

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

F. “Breakaway walls” means any type of walls, whether solid or lattice, or whether constructed of concrete, masonry, wood, metal, plastic or any other suitable building material, which are not part of the structural support of the building, and which are so designed as to break away under abnormally high tides or wave action without damage to the structural integrity of the building on which they are used, or any buildings in which they might be carried by floodwaters.

G. “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, installations which produce, use, or store hazardous materials or hazardous waste.

H. “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.

I. “Elevation certificate” means the official form from FEMA 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.

J. “FEMA” means Federal Emergency Management Agency.

K. “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 waters; and/or

2. The unusual and rapid accumulation of runoff of surface waters from any source.

L. “Flood Insurance Rate Map (FIRM)” means the official map on which FEMA has delineated both the areas of special flood hazards and the risk-premium zones applicable to the community.

M. “Flood insurance study” means the official report provided by FEMA that includes flood profiles, and the flood boundary/floodway map, and the water surface elevation of the base flood.

N. “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.

O. “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 in MVMC 15.36.240(B).

P. “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. For floodplain management purposes, the term “manufactured home” also includes park trailers, travel trailers, and other similar vehicles placed on a site for greater than 180 consecutive days. For insurance purposes, the term “manufactured home” does not include park trailers, travel trailers, and other similar vehicles.

Q. “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.

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

S. “Recreational vehicle” means a vehicle which is:

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.

T. “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 foundation 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.

U. “Structure” means a walled and roofed building including a gas or liquid storage tank that is principally above ground.

V. 1. “Substantial improvement” means any remodel, addition, repair, reconstruction or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure calculated cumulatively with any other remodel, addition, repair, reconstruction or improvement occurring during the previous 10 years and the total of all improvements or repairs are either:

a. Before the improvement or repair is started; or

b. If the structure has been damaged and is being restored, before the damage occurred.

Substantial improvement includes structures which have incurred “substantial damage,” regardless of the actual repair work performed.

2. 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 does not, however, include either:

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; or

b. Any alteration of a structure listed on the National Register of Historic Places or a state inventory of historic places; provided, that the alteration will not preclude the structure’s continued designation as a “historic structure.”

W. “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.

X. “Water dependent” means a structure for commerce or industry which cannot exist in any other location and is dependent on the water by reason of the intrinsic nature of its operations. (Ord. 3841 § 3, 2021; Ord. 3709 § 3, 2017).

Article III. General Provisions

15.36.040 Lands regulated by chapter provisions.

This chapter shall apply to all areas of special flood hazards within the jurisdiction of the city of Mount Vernon. (Ord. 2146 § 4, 1984).

15.36.050 Areas of special flood hazard – Basis for establishment.

A. The area of special flood hazard identified by FEMA in a scientific and engineering report entitled “The Flood Insurance Study for the City of

Mount Vernon, Washington, Skagit County,” dated January 3, 1985, and any revisions thereto, and “The Flood Insurance Study for Skagit County, Washington Unincorporated Areas,” dated January 3, 1985, and any revisions thereto, with accompanying flood insurance maps, and any revisions thereto, is adopted by reference and declared to be a part of this chapter.

B. The information in the flood insurance study shall be reviewed by the city and the city shall make reasonable efforts to utilize more recent and accurate data supplied by federal, state or other sources.

C. The flood insurance study is on file in the office of the building official at City Hall, 910 Cleveland Avenue, Mount Vernon, Washington, 98273. (Ord. 3709 § 4, 2017).

15.36.060 Areas of special flood hazard – Compliance.

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 the ordinance codified in this section or 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 punishable in the manner set forth in MVMC 1.20.010. Nothing herein contained shall prevent the city from taking such other lawful action as is necessary to prevent or remedy any violation. (Ord. 2322 § 2, 1988; Ord. 2146 § 6, 1984).

15.36.070 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. 2146 § 7, 1984).

15.36.080 Interpretation of provisions.

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

A. Considered as minimum requirements;

B. Liberally constructed in favor of the governing body; and

C. Demand neither to limit nor repeal any other powers granted under state statutes. (Ord. 2146 § 8, 1984).

15.36.090 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. See, for example, an earlier study by the U.S. Army Corps of Engineers which shows potential flooding depths considerably greater than those established by FEMA. 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 or flood damages. This chapter shall not create liability on the part of the city of Mount Vernon, any officer or employee thereof, or FEMA for any flood damages that result from reliance on this chapter or any administrative decision lawfully made thereunder. (Ord. 2146 § 9, 1984).

Article IV. Administration

15.36.100 Floodplain development permit – Required when – Application.

A. A floodplain development permit shall be obtained before construction or development begins within any area of special flood hazard established in MVMC 15.36.050. The permit shall be for all structures, including manufactured homes, as set forth in the definitions, MVMC 15.36.030, and for all other development including fill, excavations and other activities, also as set forth in the definitions. Application for a development permit shall be made on forms furnished by the building official or his designee, 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.

B. Specifically, the following information is required:

1. Elevation, in relation to mean sea level, of the lowest habitable floor including basement of all structures;

2. Elevation in relation to mean sea level to which any structure has been flood proofed;

3. Verification by a registered professional engineer or architect that the flood proofing methods for any nonresidential structure meet the flood proofing criteria in MVMC 15.36.250; and

4. Description of the extent to which any watercourse will be altered or relocated as a result of proposed development. (Ord. 2322 § 3, 1988; Ord. 2254 § 2, 1987; Ord. 2146 § 10(a), 1984).

15.36.110 Floodplain development permit – Exemptions.

The following shall not require a floodplain development permit:

A. Normal maintenance, resurfacing and rebuilding, at comparable grade of streets and access ways. (Ord. 3709 § 5, 2017).

15.36.120 Floodplain development permit – Building official authority.

The building official or his designee is hereby appointed to administer and implement this chapter by granting or denying floodplain development permit applications in accordance with its provisions. (Ord. 2146 § 11, 1984).

15.36.130 Building official – Duties and responsibilities.

Duties of the building official or his designee shall include, but not be limited to:

A. 1. Review all permits to determine that the permit requirements of this chapter have been satisfied,

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

3. Review all development permits to determine if the proposed development is located within the floodway and if so located to assure that the provisions of MVMC 15.36.280 are met;

B. Use of Other Base Flood Data. When base flood elevation and floodway data have not been provided in accordance with MVMC 15.36.050, the building official or his designee 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 MVMC 15.36.240, 15.36.250, 15.36.260 and 15.36.280;

C. Information to be Obtained and Maintained.

1. Where base flood elevation data is provided through the flood insurance study or required as in subsection B of this section, obtain and record the actual 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,

2. For all new or substantially improved flood proofed structures:

a. Verify and record the actual elevation (in relation to mean sea level), and

b. Maintain the flood proofing certifications required in MVMC 15.36.100,

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

D. Alteration of Watercourses.

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

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

E. Interpretation of FIRM Boundaries. Make interpretations, 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, as provided in MVMC 15.36.160 and 15.36.140 and 15.36.150. (Ord. 3218 § 4, 2004; Ord. 2322 § 4, 1988; Ord. 2266 § 1, 1987; Ord. 2254 § 3, 1987; Ord. 2146 § 12, 1984).

15.36.140 Variances – General procedures.

A. The city’s hearing examiner shall consider the application for variance, following the procedures established by MVMC Title 17 and Chapter 17.105 MVMC, and as hereinafter set forth in this chapter.

B. The landowner shall make application for variance on forms supplied by the building department. A filing fee of $100.00 shall accompany the application.

C. Decisions by the hearing examiner can be appealed to a court of competent jurisdiction.

D. The appellants shall have 10 days to file the appeal with a court of competent jurisdiction and to give notice to the building department. (Ord. 2966 § 2, 1999; Ord. 2766 § 1, 1996; Ord. 2146 § 13(a), 1984).

15.36.150 Variances – Hearing examiner – Appeal and criteria of determination.

A. The hearing examiner, as established by the city, shall hear and decide appeals and requests for variances from the requirements of this chapter.

B. The hearing examiner shall hear and decide appeals when it is alleged there is an error in any requirement, decision or determination made by the building official or his designee in the enforcement or administration of this chapter.

C. Those aggrieved by the decision of the hearing examiner, or any taxpayer, may appeal such decision to a court of competent jurisdiction, as provided by MVMC 17.105.080.

D. In passing upon such applications, the hearing examiner shall consider all technical evaluations, all relevant factors, standards specified in other sections of this chapter, and:

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

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

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

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

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

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

7. The compatibility of the proposed use with existing and anticipated development;

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

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

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

11. The cost 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. Generally, the only circumstance under which a variance may be issued is for new construction and substantial improvements to be erected on a lot of one-half acre or less in size contiguous to and surrounded by lots with existing structures constructed below the base flood level, providing subsections (D)(1) through (D)(11) 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.

F. Upon consideration of the factors of subsection D of this section and the purpose of this chapter, the hearing examiner may attach such conditions to the granting of variances as it deems necessary to further the purposes of this chapter.

G. The building official or his designee shall maintain the records of all appeal actions and report any variances to FEMA upon request. (Ord. 2966 § 3, 1999; Ord. 2766 § 2, 1996; Ord. 2322 § 5, 1988; Ord. 2146 § 13(b), 1984).

15.36.160 Variances – Issuance conditions.

A. 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 section.

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

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

D. Variances shall only be issued upon:

1. A showing of good and sufficient cause;

2. A determination that failure to grant the variance would result in exceptional hardship to the applicant; and

3. 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 MVMC 15.36.150D, or conflict with existing local laws or ordinances.

E. 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.

F. Variances may be issued for nonresidential buildings in very limited circumstances to allow a lesser degree of flood proofing than watertight or dry-floodproofing, where it can be determined that such action will have low damage potential, complies with all other variance criteria except subsection A of this section, and otherwise complies with MVMC 15.36.180 and 15.36.190.

G. 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. 2266 § 2, 1987; Ord. 2254 § 4, 1987; Ord. 2146 § 13(c), 1984).

Article V. Provisions for Flood Hazard Protection

15.36.170 General standards.

In all areas of special flood hazard, the standards set out in MVMC 15.36.170 through 15.36.220 are required. (Ord. 2146 § 14, 1984).

15.36.180 Anchoring.

A. All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure.

B. 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. 2254 § 5, 1987; Ord. 2146 § 14(a), 1984).

15.36.190 Construction materials and methods.

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

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

C. 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 and shall comply with the elevation requirements outlined in subsection D of this section.

D. All new, substantially improved, and/or reconstructed residential structures and manufactured homes shall:

1. Have their indoor machinery and equipment that are part of the building elevated such that they are no less than one foot above the base flood elevation.

2. Have their outdoor machinery and equipment that are part of the building strapped or bolted onto a platform that is no less than one foot above the base flood elevation. (Ord. 3841 § 4, 2021).

15.36.200 Utilities.

A. All new and replacement water-supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system. In addition, water wells shall be located on high ground that is not in the floodway;

B. 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

C. On-site waste-disposal systems shall be located to avoid impairment to them or contamination from them during flooding. (Ord. 3709 § 6, 2017).

15.36.220 Building permit review restrictions where flood data not available.

Where elevation data is not available either through the flood insurance study or from another authoritative source (MVMC 15.36.130(B)), 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. 2254 § 8, 1987; Ord. 2146 § 14(e), 1984).

15.36.230 Specific standards and requirements.

In all areas of special flood hazards where base flood elevation data has been provided as set forth in MVMC 15.36.050, subsection B of MVMC 15.36.130, or the provisions set out in MVMC 15.36.220 through 15.36.260 are required. (Ord. 2146 § 15, 1984).

15.36.240 Residential construction.

A. In AE and A1-30 zones or other A-zoned areas where the BFE has been determined or can be reasonably obtained, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE. Mechanical equipment and utilities shall be elevated at least one foot above the BFE.

B. 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:

1. 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.

2. The bottom of all openings shall be no higher than one foot above grade.

3. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters. (Ord. 3841 § 5, 2021).

15.36.250 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 the level of one foot or more above the base flood elevation, or, together with attendant utility and sanitary facilities, shall:

A. Be dry floodproofed so that below one foot above the base flood level the structure is watertight, with walls substantially impermeable to the passage of water or dry floodproofed to the elevation required by ASCE 24, whichever is greater;

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

C. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in MVMC 15.36.130(C);

D. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in MVMC 15.36.240(B); and

E. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building floodproofed to the base flood level will be rated as one foot below. Floodproofing the building an additional foot will reduce insurance premiums). (Ord. 3841 § 6, 2021).

15.36.255 Critical facilities.

Construction of new critical facilities shall be, to the extent possible, located outside the limits of the base floodplain. Construction of new critical facilities shall be permissible within the base floodplain if no feasible alternative site is available. Critical facilities constructed within the base floodplain shall have the lowest floor elevated to three feet or more above the level of the base flood elevation at the site. 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 base floodplain shall be provided to all critical facilities to the extent possible. (Ord. 2322 § 8, 1988).

15.36.260 Manufactured homes.

A. All manufactured homes to be placed or substantially improved within zones A1 – 30, AH and AE:

1. All manufactured homes to be placed or substantially improved on sites shall be elevated on a permanent foundation such that the lowest floor and mechanicals of the manufactured home are elevated one foot or more above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement. (Ord. 3841 § 7, 2021; Ord. 3218 § 5, 2004; Ord. 2322 § 9, 1988; Ord. 2254 § 11, 1987; Ord. 2146 § 15(c), 1984).

15.36.265 Recreational vehicles.

Recreational vehicles placed on sites are required to either:

A. Be on site for fewer than 180 consecutive days;

B. Be fully licensed and ready for highway use, on their wheels or jacking systems, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or

C. Meet the same requirements of MVMC 15.36.260 for the elevation and anchoring requirements for manufactured homes. (Ord. 3218 § 6, 2004).

15.36.270 Dike setback area restrictions.

A. Projects for which a floodplain development permit is required are prohibited between the riverward toe of dikes and levees along the Skagit River and a line 50 feet landward of the landward toe of said dikes and levees, except that this prohibition shall not apply to improvements to the dikes and levees themselves, or improvements designed to aid in floodproofing.

B. Facilities intended for or likely to be used primarily as residential care for the elderly or the handicapped, or any other persons with a limited ability to evacuate quickly in an emergency, shall be prohibited between the riverward toe of dikes and levees along the Skagit River and a line 1,000 feet from landward of the landward toe of said dikes and levees.

C. Dike setbacks in the AO depth one-foot zone will be evaluated on a case-by-case basis by the building official and the city engineer. If both officials concur, zero dike setback may be allowed; however, flood-fighting access must be provided. (Ord. 2146 § 15(c), 1984).

15.36.280 Floodway use restrictions.

Located within areas of special flood hazard established in MVMC 15.36.050 are areas designated as floodways. Zone AI, the main stream of the Skagit River, is to be treated as a floodway. 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 or architect is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment shall 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, reconstruction, or repair is started, or (b) if the structure has been damaged, and is being restored, before the damage occurred. Work done on structures 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, shall not be included in the 50 percent figure;

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 Article V of this chapter, Provisions for Flood Hazard Protection;

D. Prohibit the placement of any mobile homes except in an existing mobile home park or existing mobile home subdivision. (Ord. 3709 § 7, 2017).

15.36.285 Requirements for zones AE, AH and A1 – 30.

In areas with base flood elevations (but a regulatory floodway has not been designated), no new construction, substantial improvements, or other development (including fill) shall be permitted within zones A1 – 30, AH and AE on the community’s FIRM, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the community. (Ord. 3841 § 8, 2021).

15.36.290 Shallow flooding (AO zone) areas – Special requirements.

Shallow flooding areas appear on FIRMs as AO zones with depth designations. The base flood depths in these zones range from one to three feet above ground where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. In addition to other provisions in this code, the following additional provisions also apply in AO zones:

A. Dike setback from 50 feet shall conform to MVMC 15.36.270.

B. New construction and substantial improvements of residential structures and manufactured homes within all AO zones shall have the lowest floor (including basement and mechanical equipment) elevated above the highest adjacent grade to the structure, one foot or more above the depth number specified in feet on the community’s FIRM.

C. Where velocities of five feet per second or greater are listed in an AO zone, new construction and substantial improvements to residential structures within 200 feet of the toe of any dike shall be constructed to the following standards in addition to those listed above:

1. All buildings or structures shall be elevated so that the lowest supporting member is located no lower than one foot above the base flood elevation level, with all space below the lowest supporting member open so as not to impede the flow of water for breakaway walls provided for in subsection (C)(6) of this section.

2. All buildings or structures shall be securely anchored on pilings or columns.

3. Pilings or columns used as structural support shall be designed and anchored so as to withstand all applied loads of the base flood flow.

4. Compliance with provisions of subsections (C)(1), (2) and (3) of this section shall be certified to by a registered professional engineer or architect.

5. There shall be no fill used for structural support.

6. Breakaway walls shall be allowed below the base flood elevation, provided they are not a part of the structural support of the building, and are designed so as to break away under abnormally high water velocities without damage to the structural integrity of the building on which they are to be used.

D. New construction and substantial improvements of nonresidential structures within AO zones shall either:

1. Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, immediately adjacent to the building, one foot or more above the depth number specified on the FIRM; or

2. Together with attendant utility and sanitary facilities, be completely floodproofed to or above that level so that any space below that level is watertight, with walls substantially impermeable to the passage of water, and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect; or

3. If located in an AO zone with water velocities of five feet per second or greater and within 200 feet of the toe of a dike, be constructed to the standards of subsections (C)(1) through (6) of this section.

E. New construction and substantial improvements of nonresidential structures within AO zones shall require adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures. (Ord. 3841 § 9, 2021).

15.36.295 Wetlands management.

To the maximum extent possible, avoid the short and long-term adverse impacts associated with the destruction or modification of wetlands, especially those activities which limit or disrupt the ability of the wetland to alleviate flooding impacts. The following process should be implemented:

A. Review proposals for development within base floodplains for their possible impacts on wetlands located within the floodplain;

B. Ensure that development activities in or around wetlands do not negatively affect public safety, health, and welfare by disrupting the wetlands’ ability to reduce flood and storm drainage;

C. Request technical assistance from the Department of Ecology in identifying wetland areas. Existing wetland map information from the National Wetlands Inventory (NWI) can be used in conjunction with the community’s FIRM to prepare an overlay zone indicating critical wetland areas deserving special attention. (Ord. 2322 § 11, 1988).

Article VI. Intent to Administer Flood-Control Zone Permit Program Pursuant to RCW 86.16.085

15.36.300 Statutory authority – Revisions or amendments to program.

Pursuant to RCW 86.16.085, the city shall administer a permit program for the conception of improvement in flood-control zones, as defined in and in accordance with the provisions of Chapter 86.16 RCW and Chapter 508-60 WAC; provided, however, that the permit program as administered by the city of Mount Vernon shall be revised as necessary and to the satisfaction of the Department of Ecology to conform with any changes in the state rules pertaining to flood-control zones which may be adopted by the Department of Ecology subsequent to the effective date of the ordinance codified in this chapter; and provided further, that all amendments to this chapter shall be submitted for information purposes to the Department of Ecology. (Ord. 2146 § 18, 1984).