Chapter 16.15
FLOOD HAZARD AREAS

Sections

16.15.010    Title.

16.15.020    Application.

16.15.030    Purpose.

16.15.040    Authority.

16.15.050    Basis for establishing the areas of special flood hazard.

16.15.060    Abrogation and greater restrictions.

16.15.070    Interpretation.

16.15.080    Warning and disclaimer of liability.

16.15.090    Establishment of development permit.

16.15.100    Designation and duties and responsibilities of the local administrator.

16.15.110    Use of other base flood data (in A and V Zones).

16.15.120    Information to be obtained and maintained.

16.15.130    Alteration of watercourses.

16.15.140    Interpretation of FIRM boundaries.

16.15.150    Appeal and exemptions.

16.15.160    Exemptions.

16.15.170    Provisions for flood hazard protection – General standards.

16.15.180    Specific standards.

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

16.15.200    Floodways.

16.15.220    Wetlands management.

16.15.230    Compliance with federal and state permits required.

16.15.240    Coastal high hazard area.

16.15.250    Encroachments.

16.15.010 Title.

This chapter shall be entitled “Flood Hazard Areas Code.” [Ord. 1583 § 89, 2013.]

16.15.020 Application.

This chapter applies to all development on all properties within areas of flood hazard, as further defined by this chapter. [Ord. 1583 § 90, 2013.]

16.15.030 Purpose.

The purpose of this chapter is to implement the provisions of chapter 86.16 RCW in coordinating the flood plain management regulation aspects of the National Flood Insurance Program. [Ord. 1583 § 91, 2013.]

16.15.040 Authority.

This chapter is adopted pursuant to chapter 18.86 RCW, chapter 173-158 WAC and WAC 173-220-030. [Ord. 1583 § 92, 2013.]

16.15.050 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 “The Flood Insurance Study for King County, Washington and Incorporated Areas,” Volumes 1 through 3, dated November 8, 1999, with accompanying flood insurance maps is adopted by reference and declared to be a part of this chapter. Not less than one copy of the flood insurance study shall be filed in the Building Official’s office and be available for use and examination by the public. [Ord. 1583 § 93, 2013.]

16.15.060 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. The best available information for flood hazard area identification as outlined in Section 4.3-2 shall be the basis for regulation until a new FIRM is issued that incorporates data utilized under Section 4.3-2. [Ord. 1583 § 94, 2013.]

16.15.070 Interpretation.

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

(1) Considered as minimum requirements; and

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

(3) Deemed neither to limit nor repeal any other powers granted to the City under state statutes. [Ord. 1583 § 95, 2013.]

16.15.080 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 any legal liability on the part of the City, any officer or employee thereof, or the Federal Insurance Administration, for any flood damages that result from reliance on this chapter or any lawfully made administrative decision. [Ord. 1583 § 96, 2013.]

16.15.090 Establishment of development permit.

A development permit shall be obtained before construction or development begins within any area of flood hazard established in DMMC 16.15.060. The permit shall be for all structures including manufactured homes and for all other development including fill and other activities. Application for a development permit shall be made on forms furnished by the local administrator and 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; existing or proposed structures, fill, on-site storage of materials, drainage facilities; and the location of the foregoing. Specifically, the following information shall be furnished by the applicant:

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

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

(3) Certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet the floodproofing criteria in DMMC 16.15.180(2); and

(4) Description of the extent to which any watercourse will be altered or relocated as a result of proposed development; and

(5) A report reviewed and approved by an appropriate state or federal agency(ies) which identifies and assesses habitat impacts, if any, and proposes conservation methods consistent with federal permitting requirements. Preparation of the report shall be the responsibility of the applicant and shall utilize the expertise of a biologist specializing in wetland, riverine, or coastal zone ecology. [Ord. 1583 § 97, 2013.]

16.15.100 Designation and duties and responsibilities of the local administrator.

The local administrator is hereby appointed to administer and implement this Title by granting or denying development permit applications in accordance with its provisions.

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

(1) Reviewing all development permits to determine that the permit requirements of this chapter have been satisfied; and

(2) Reviewing all development permits to determine that all necessary permits have been obtained from those federal, state, or local governmental agencies from which prior approval is required; and

(3) Reviewing all development permits to determine if the proposed development is located in the floodway. If located in the floodway, assure that the encroachment provisions of DMMC 16.15.200(1) are met. [Ord. 1583 § 98, 2013.]

16.15.110 Use of other base flood data (in A and V Zones).

When base flood elevation data has not been provided (in A or V Zones) in accordance with DMMC 16.15.050, the local administrator shall obtain, review, and reasonably utilize any base flood elevation and floodway data available from a federal, state, or other source, in order to administer DMMC 16.15.180(1), (2), (3), and (4) and 16.15.200. [Ord. 1583 § 99, 2013.]

16.15.120 Information to be obtained and maintained.

(1) Where base flood elevation data is provided through flood insurance studies or as in DMMC 16.15.110, 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 floodproofed structures where base flood elevation data is provided through the FIS, FIRM, or as required in DMMC 16.15.130:

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

(b) Maintain the floodproofing certifications required in DMMC 16.15.090(3).

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

(4) In coastal high hazard areas, certification shall be obtained from a registered professional engineer or architect that the structure is securely anchored to adequately anchored pilings or columns in order to withstand high velocity waters, storm surges, and tsunamis. [Ord. 1583 § 100, 2013.]

16.15.130 Alteration of watercourses.

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

(2) Require that maintenance is provided within the altered or relocated portion of the watercourse so that the flood-carrying capacity is not diminished. [Ord. 1583 § 101, 2013.]

16.15.140 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 DMMC 16.15.170. Such appeals shall be granted consistent with the standards of Section 60.6 of Appeals and Regulations of the National Flood Insurance Program (44 C.F.R. 59 through 76). [Ord. 1583 § 102, 2013.]

16.15.150 Appeal and exemptions.

Appeals of administrative orders, decisions or determinations under this chapter shall be processed pursuant to chapter 18.20 DMMC. [Ord. 1583 § 103, 2013.]

16.15.160 Exemptions.

(1) When considering an application for an exemption to any provisions of this chapter, the Hearing Examiner shall consider all technical evaluations, all relevant factors and standards specified in other sections of this chapter, and:

(a) The danger that materials may be swept onto other lands to the injury of others; and

(b) The danger to life and property due to flooding or erosion damage; and

(c) The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner; and

(d) The importance of the services provided by the proposed facility to the community; and

(e) The necessity to the facility of a waterfront location, where applicable; and

(f) The availability of alternate locations for the proposed use which are not subject to flooding or erosion damage; and

(g) The compatibility of the proposed use with existing and anticipated development; and

(h) The relationship of the proposed use to the Comprehensive Plan and floodplain management program for that area; and

(i) The safety of access to the property in times of flood for ordinary and emergency vehicles; and

(j) The expected height, velocity, duration, rate of rise, and sediment transport of the flood waters 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) Conditions/Criteria for Exemptions.

(a) Generally, the only condition under which an exemption from the elevation standard may be granted shall be 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 base flood level; provided, that the exemption criteria listed above have been fully considered.

(b) Exemptions may be granted 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 procedure set forth in this section.

(c) Exemptions shall not be granted within a designated floodway if any increase in flood levels during the base flood discharge would result.

(d) Exemptions shall only be granted upon a determination that the exemption is the minimum necessary, considering the flood hazard, to afford relief.

(e) Exemptions shall only be granted upon:

(i) A showing of good and sufficient cause; and

(ii) A determination that failure to grant the exemption would result in exceptional hardship to the applicant; and

(iii) A determination that the granting of an exemption 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 or conflict with existing local laws or ordinances.

(f) Exemptions as interpreted in the National Flood Insurance Program are based on the general zoning law principle that such exemptions pertain to a physical piece of property; such exemptions are not personal in nature and do not pertain to a structure, inhabitants thereof, or economic or financial circumstances.

(g) Exemptions may be granted 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 has a low damage potential, complies with all other exemption criteria except DMMC 16.15.180(1)(b), and otherwise complies with the general standards of this chapter.

(h) Any applicant to whom an exemption 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. 1583 § 104, 2013.]

16.15.170 Provisions for flood hazard protection – General standards.

In all areas of special flood hazards, the following standards are required:

(1) 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, FEMA 85).

(2) 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.

(3) Utilities.

(a) All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system.

(b) New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharge from the systems into flood waters.

(c) On-site waste disposal systems shall be located to avoid impairment to such systems or contamination from such systems during flooding. Locating such equipment below the base flood elevation may cause annual flood insurance premiums to be increased.

(4) Subdivision Proposals.

(a) All subdivision proposals shall be consistent with the need to minimize flood damage.

(b) All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flooding.

(c) All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage.

(d) Base flood elevation data shall be provided for subdivision proposals and other proposed developments which contain at least 10 lots or 1 acre, whichever is less. 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 developments which contain at least 50 lots or 5 acres (whichever is less).

(5) Review of Building Permits. Where elevation data is not available either through the flood insurance study or from another authoritative source, applications for building permits shall be reviewed by the Building Official 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. 1583 § 105, 2013.]

16.15.180 Specific standards.

In all areas of special flood hazards where base flood elevation data has been provided as set forth in DMMC 16.15.060 or 16.15.130, the following provisions are required:

(1) Residential Construction.

(a) New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to or above base flood elevation.

(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 flood waters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:

(i) A minimum of two openings having a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding shall be provided.

(ii) The bottom of all openings shall be no higher than one foot above grade.

(iii) Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of flood waters.

(2) 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 or above the level of the base flood elevation; or, together with attendant utility and sanitary facilities, shall:

(a) Be floodproofed so that below one foot above the base flood level the structure is watertight with walls substantially impermeable to the passage of water; and

(b) Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and

(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 local administrator as required by Section 106.3.4.1 IBC and Section 106.1 IRC.

(d) Nonresidential structures that are elevated, but not floodproofed, must meet the same standards for space below the lowest floor as described in subsection (1)(b) of this section.

(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 one foot above the base flood level will be rated as at the base flood level).

(3) Manufactured Homes. All manufactured 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 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. This subsection applies to new manufactured homes placed on any site, manufactured homes in a new or expanded manufactured home park or subdivision, and new manufactured homes in an existing manufactured home park and subdivision.

(4) Recreational Vehicles. (44 CFR 60.3(c)(14)) Recreational vehicles placed on sites are required to either:

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

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

(c) Meet the requirements of DMMC 16.15.170 and this section and the elevation and anchoring requirements for manufactured homes. [Ord. 1583 § 106, 2013.]

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

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 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. 1583 § 107, 2013.]

16.15.200 Floodways.

Located within areas of special flood hazard established in DMMC 16.15.050 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles, and erosion potential, the following provisions apply:

(1) 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 would not result in any increase in flood levels during the occurrence of the base flood discharge.

(2) Construction or reconstruction of residential structures is prohibited within designated floodways, except for:

(a) Repairs, reconstruction, or improvements to a structure which do not increase the ground floor area; and

(b) Repairs, reconstruction or improvements to a structure, the cost of which does not exceed 50 percent of the market value of the structure either:

(i) Before the repair, or reconstruction is started; or

(ii) If the structure has been damaged, and is being restored, before the damage occurred. Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions, or to structures identified as historic places, may be excluded in the 50 percent.

(3) If subsection (1) of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of DMMC 16.15.190 and 16.15.200. [Ord. 1583 § 108, 2013.]

16.15.220 Wetlands management.

To the maximum extent possible, each development subject to this chapter shall avoid the short-term 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 shall be implemented for such development:

(1) Review proposals for development within base floodplains for their possible impacts on wetlands located within the floodplain.

(2) Ensure that development activities in or around wetlands do not negatively affect public safety, health, and welfare by disrupting the ability of the wetland to reduce flood and storm drainage.

(3) Request technical assistance from the Department of Ecology in identifying wetland areas. Existing wetland map information from the National Wetlands Inventory (NWI) may be used in conjunction with the area’s FIRM to prepare an overlay zone indicating critical wetland areas deserving special attention. [Ord. 1583 § 109, 2013.]

16.15.230 Compliance with federal and state permits required.

No approval of an application for a development permit within an area of special flood hazard shall be issued without first demonstrating compliance with all necessary federal and state environmental permit requirements, including, but not limited to, Clean Water Act, 33 U.S.C. 1344, Section 404 permits and Endangered Species Act, 16 U.S.C. 1531, Section 10 permits. [Ord. 1583 § 110, 2013.]

16.15.240 Coastal high hazard area.

Located within areas of special flood hazard established in DMMC 16.15.050 are coastal high hazard areas, which are designated as Zones V1-V30, VE, and/or V. These areas have special flood hazards associated with high velocity waters from surges and, therefore, in addition to meeting all provisions in this chapter, the following provisions shall also apply:

(1) All new allowable construction and substantial improvement in Zones V1-V30 and VE (V if base flood elevation data is available) shall be elevated on pilings and columns so that:

(a) The bottom of the lowest horizontal structural member of the lowest floor (excluding the pilings or columns) is elevated to or above the base flood level; and

(b) The pile or column foundation and structure attached thereto is anchored to resist flotation, collapse, and loads acting simultaneously on all building components. Wind and water loading values shall each have a one percent chance of being equaled or exceeded in any given year (100-year mean recurrence interval).

(c) A registered professional engineer or architect shall develop or review the structural design, specifications, and plans for the construction and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of subsections (1)(a) and (b) of this section.

(2) Obtain the elevation (in relation to mean sea level) of the bottom of the lowest structural member of the lowest floor (excluding pilings and columns) of all new and substantially improved structures in Zones V1-V30 and VE, and whether or not such structures contain a basement. The local administrator shall maintain a record of all such information.

(3) All new construction shall be located landward of the reach of mean high tide.

(4) Provide that all new construction and substantial improvements have the space below the lowest floor either free of obstruction or constructed with nonsupporting breakaway walls, open wood lattice-work, or insect screening intended to collapse under wind and water loads without causing collapse, displacement or other structural damage to the elevated portion of the building or supporting foundation system. For the purpose of this section, a breakaway wall shall have a design safe loading resistance of not less than 10 and no more than 20 pounds per square foot. Use of breakaway walls which exceed a design safe loading resistance of 20 pounds per square foot (either by design or when so required by local or state codes) may be permitted only if a registered professional engineer or architect certifies that the designs proposed meet the following conditions:

(a) Breakaway wall collapse shall result from a water load less than that which would occur during the base flood; and

(b) The elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement, or other structural damage due to the effects of wind and water loads acting simultaneously on all building components (structural and nonstructural). Maximum wind and water loading values to be used in this determination shall each have a one percent chance of being equaled or exceeded in any given year (100-year mean recurrence interval).

(5) If breakaway walls are utilized, such enclosed space shall be usable solely for parking of vehicles, building access, or storage. Such space shall not be used for human habitation.

(6) Prohibit the use of fill for structural support of buildings.

(7) Prohibit manmade alteration of sand dunes which would increase potential flood damage.

(8) Manufactured homes proposed in coastal high hazard areas must meet all V Zone standards. [Ord. 1583 § 111, 2013.]

16.15.250 Encroachments.

The cumulative effect of any proposed development, when combined with all other existing and anticipated development, shall not increase the water surface elevation of the base flood more than one foot at any point. [Ord. 1583 § 112, 2013.]