Chapter 15.630
FREQUENTLY FLOODED AREAS

Sections:

15.630.010    Designation of frequently flooded areas.

15.630.020    Critical area report requirements – Frequently flooded areas.

15.630.030    Warning and disclaimer of liability.

15.630.040    Performance standards – General requirements.

15.630.050    Performance standards – Specific uses.

15.630.060    Performance standards – Areas of shallow flooding.

15.630.070    Prohibited uses and activities.

15.630.010 Designation of frequently flooded areas.

A.    Frequently Flooded Areas. Frequently flooded areas shall include:

1.    Areas Identified on the Flood Insurance Map(s). Those areas of special flood hazard within the incorporated city limits of Ellensburg identified as being within the 100-year floodplain by the Federal Insurance Administration in a scientific and engineering report entitled “The Flood Insurance Study for Ellensburg, Dated November 5, 1980,” with accompanying flood insurance rate and floodway maps (FIRM Community Panel Number 530234 0001C; Community Panel Number 530234 0002C; Floodway Community Panel Number 530095 0552C; all maps effective May 5, 1981). The above study and maps are hereby adopted by reference and declared to be a part of this chapter. The flood insurance study and maps are on file with the Ellensburg community development department, located at 501 N. Anderson Street in Ellensburg, Washington.

B.    Use of Additional Information. The director may use additional flood information that is more restrictive or detailed than that provided in the flood insurance study conducted by the Federal Emergency Management Agency (FEMA) to designate frequently flooded areas, including data on channel migration, historical data, high water marks, photographs of past flooding, location of restrictive floodways, maps showing future build-out conditions, maps that show riparian habitat areas, or similar information.

C.    Flood Elevation Data. When base flood elevation data is not available (A and V zones designated under subsection (A) of this section), the director shall obtain, review, and reasonably utilize any base flood elevation and floodway data available from a federal, state, county or other source, in order to administer this section.

D.    Designation Made by Director. The flood insurance maps are to be used as a guide for the city, project applicants and/or property owners and the public, and should be considered a minimum designation of frequently flooded areas. Because flood insurance maps may be continuously updated as areas are reexamined or new areas are identified, the best available information for flood hazard area identification shall be the basis for regulation.

E.    Supplemental Documentation. Any areas identified by the director in this section shall be supported by professional scientific information.

F.    Maintenance of Records. The director shall maintain for public inspection all records of floodplain hazards, certificates of floodproofing, and flood elevation data.

G.    Mapping. The location and extent of frequently flooded areas are shown on the critical area maps adopted with the ordinance codified in this chapter by the city. The following maps and data are hereby adopted and are available from the city and/or the listed governmental agency: Federal Emergency Management Administration Flood Insurance Rate Maps; Community Panels: 530234 0001C; 530234 0002C; 530095 0439B; 530095 0552C; 530095 0443B; 530095 0556B; 530095 0554C. [Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.020 Critical area report requirements – Frequently flooded areas.

A.    Prepared by a Qualified Professional. A frequently flooded areas report shall be prepared for development within floodplains. Such report shall be required to be prepared by a qualified professional who is a hydrologist or engineer, and who is licensed in the state of Washington with experience in preparing flood hazard assessments.

B.    Areas Addressed in Critical Area Report. The following areas shall be addressed in a critical area report for frequently flooded areas:

1.    The location of the proposed activity;

2.    All areas of a special flood hazard area, as indicated on the flood insurance map(s) within 200 feet of the project area; and

3.    All other flood areas indicated on the flood insurance map(s) within 200 feet of the project area.

C.    Flood Hazard Assessment Required. A critical area report for a proposed activity within a frequently flooded area shall contain a flood hazard assessment including the following site- and proposal-related information at a minimum:

1.    Site and Construction Plans. A copy of the site and construction plans for the development proposal showing:

a.    Floodplain (100-year flood elevation); 10-year and 50-year flood elevations and floodway, if required by the director and, in addition, other critical areas, buffers, and shoreline areas;

b.    Proposed development, including the location of existing and proposed structures, fill, storage of materials, and drainage facilities, with dimensions indicating distances to the floodplain;

c.    Extent and location of proposed clearing and grading activity; and

d.    Elevation of the lowest floor (including basement) of all structures, and the level to which any structure has been floodproofed;

2.    Floodproofing Certificate. When floodproofing is proposed, a certification by a registered professional engineer or architect that the floodproofing methods meet the requirements of ECC 15.630.040(G), Floodproofing;

3.    Watercourse Alteration. When watercourse alteration is proposed, the critical area report shall include:

a.    Extent of Watercourse Alteration. A description of and plan showing the extent to which a watercourse will be altered or relocated as a result of the proposal; and

b.    Maintenance Program Required for Watercourse Alterations. A maintenance program that provides maintenance practices for the altered or relocated portion of the watercourse to ensure that the flood-carrying capacity is not diminished;

4.    Information Regarding Other Critical Areas. Potential impacts to wetlands, fish and wildlife habitat and other critical areas shall be addressed in accordance with the applicable sections of this chapter. [Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.030 Warning and disclaimer of liability.

The degree of flood protection required by this chapter poses 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 frequently flooded 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 city, any officer or employee thereof, or the Federal Insurance Administration, for any flood damage that results from reliance on this chapter or any administrative decision lawfully made hereunder. [Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.040 Performance standards – General requirements.

A.    Permit(s) Required. The permit required by this section shall be incorporated into the basic underlying permits necessary for the project or activity to proceed within a frequently flooded area, e.g., building permit, short plat, public works permits, State Environmental Policy Act and city critical areas reviews, and similar permits and development reviews. Completion of and compliance with the necessary review processes and permits listed above shall satisfy the requirement of issuance of a development permit for any activity that would alter land or commence a new use within a frequently flooded area.

B.    All necessary permits shall be obtained. The director shall verify that all necessary permits have been obtained from those governmental agencies from which prior approval is required by federal, state, or local law, including but not limited to Section 404 of the Federal Water Pollution Control Act Amendment of 1972 and the Endangered Species Act of 1973.

C.    Development proposals must not reduce the effective base flood storage volume of a floodplain. Grading or other activity that would reduce the effective storage volume must be mitigated by creating compensatory storage on the site. The compensatory storage must provide equivalent volume at equivalent elevations to that being displaced, be hydraulically connected to the source of the flooding, be provided in the same construction season, and occur on-site or off-site, if legal arrangements can be made to assure that the effective compensatory storage will be preserved over time.

D.    Areas without Base Flood Elevation Data. Where base flood elevation data is not available (A and V zones designated under ECC 15.630.010(A)), and there is insufficient data available from federal, state, county, or other sources, the director shall determine the base flood elevation using historical data, high water marks, photographs of past flooding, and other available information. If there is insufficient data available for the director to make a determination of the base flood elevation, and standards requiring a base flood elevation cannot be implemented, the director shall require measures that assure the proposed structures will be reasonably safe from flooding. At a minimum, the base flood elevation shall be set at least two feet above the highest adjacent grade. The director shall have the authority to set an average base flood elevation if there are sufficient grade deficiencies in elevation around the development area.

E.    Construction Materials and Methods.

1.    Methods That Minimize Flood Damage. All new construction and substantial improvements shall be constructed using flood-resistant materials and utility equipment, and with methods and practices that minimize flood damage.

2.    Structures Shall Be Located Outside the Floodplain. All structures shall be located on the buildable portion of the site out of the floodplain unless there is no buildable site area out of the floodplain. For sites with no buildable area out of the floodplain, structures shall be placed on the highest land on the site, oriented parallel to the anticipated flow of water rather than perpendicular, and sited as far from the watercourse and other critical areas as possible. If the director finds any evidence of active hyporheic exchange on a site, the development shall be located to minimize disruption of such exchange.

3.    Utilities Shall Be Protected. All utilities shall be located on the buildable portion of the site out of the floodplain unless there is no buildable site area out of the floodplain. 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 their components during conditions of flooding. Water wells shall be located on high ground that is not in the floodway per WAC 173-10-171.

F.    Elevation Certificate Required Following Construction. Following construction or substantial improvement of a structure within the floodplain where the base flood elevation is provided, the applicant shall be required to submit to the director an as-built elevation certificate from a licensed professional land surveyor that records the elevation of the lowest floor (including basement), and whether or not the structure contains a basement. The director shall obtain said as-built elevation certificate and maintain for public inspection said certificates in its official records.

G.    Floodproofing.

1.    When a nonresidential structure is to be floodproofed, it shall be designed and constructed using methods that meet the following requirements:

a.    Watertight Structure. The structure shall be watertight with walls substantially impermeable to the passage of water below one foot above the base flood level;

b.    Hydrostatic Resistance. Structural components shall be capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and

c.    Certified by a Registered Professional Engineer or Architect. The structure shall 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.

2.    Floodproofing Certificate Required Following Construction. Following construction of the structure, the applicant shall obtain and provide to the director a floodproofing certificate from a registered professional engineer or architect that records the actual (as-built) elevation to which the structure was floodproofed.

3.    Floodproofing Nonresidential Buildings. Applicants floodproofing nonresidential buildings shall be notified by the director that flood insurance premiums will be based on rates that are one foot below the floodproofed level (for example, a building floodproofed to the base flood level will be rated as one foot below).

H.    Anchoring.

1.    Anchoring Required. All new construction and substantial improvements within the floodplain shall be anchored to prevent flotation, collapse, or lateral movement of the structure.

2.    Manufactured Homes Shall Be Anchored. All manufactured homes placed within the floodplain must 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.

I.    Fill and Grading. Fill and grading within the floodplain shall only occur after the review and approval by the city of the clearing, grading, and fill proposal. Such proposal shall require a determination from a licensed professional engineer that the fill or grading will not block side channels, inhibit channel migration, increase flood hazards to others, or be placed within a channel migration zone, whether or not the city delineated such zones as of the time of the application. [Ord. 4803 § 7, 2018; Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.050 Performance standards – Specific uses.

In all frequently flooded areas the following standards are required:

A.    Residential Construction.

1.    Must be no lower than one foot above the base flood elevation. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to one foot above the base flood elevation for the area; and

2.    Areas below the lowest floor must meet requirements for crawlspaces as set forth hereinabove in this chapter.

B.    Manufactured Homes Must Be Elevated. All manufactured homes to be placed or substantially improved 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.

C.    Recreational Vehicles. Recreational vehicles are required to either:

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

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

3.    Must obtain a development permit and meet the requirements of this section, including elevation and anchoring, for manufactured homes.

D.    Nonresidential Construction.

1.    Must be no lower than one foot above the base flood elevation. Construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated to one foot above the base flood elevation for the area or, together with attendant utility and sanitary facilities, shall be floodproofed in accordance with ECC 15.630.040(G), Floodproofing. Unavoidable impacts to flooded areas (from fill) need to be mitigated; and

2.    Areas below the lowest floor must meet the requirements for crawlspaces set forth hereinabove in this chapter.

E.    Utilities.

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

2.    Sanitary sewage systems. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters.

F.    Subdivision Proposals.

1.    All subdivisions and short subdivisions shall:

a.    Minimize flood damage. Subdivisions and short subdivisions shall be designed to minimize or eliminate flood damage to proposed structures; and public utilities and facilities that are installed as part of such subdivisions, such as sewer, gas, electrical, and water systems, shall be located and constructed to minimize flood damage. Subdivisions should be designed using natural features of the landscape, and should not incorporate flood protection changes;

b.    Have adequate drainage. Subdivisions and short subdivisions shall have adequate natural surface water drainage in accordance with city’s public works development standards to reduce exposure to flood hazards; and

c.    Show flood areas on plat maps. Subdivisions and short subdivisions shall show the 100-year floodplain, floodway, and channel migration zone where designated by the city on the preliminary and final plat and short plat maps.

2.    Detailed base flood elevation data shall be generated for subdivisions of at least 50 lots or five acres. Where detailed 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 five acres.

G.    Alteration of Watercourses.

1.    Shall require the submission of a critical area report by the applicant and be in accordance with the habitat regulations set forth in ECC 15.650.020 and 15.650.030 et seq. Watercourse alterations shall only be allowed when no negative impacts occur to critical areas.

2.    Shall not result in blockage. Watercourse alteration projects shall not result in blockage of side channels.

3.    Notification Required. The city shall notify adjacent communities, the Washington State Department of Ecology, the Washington Department of Fish and Wildlife, and the Federal Insurance Administration of the proposed watercourse alteration at least 30 days prior to permit issuance.

4.    Maintenance of Alterations. The applicant shall maintain the altered or relocated portion of the watercourse to ensure that the flood carrying capacity is not diminished. The applicant shall furnish the city with a surety bond for maintenance, which bond shall remain in effect for a period of five years after completion of the alterations and be in accordance with a maintenance program approved by the director for the alteration project. The bond shall be in an amount to be determined by the director as sufficient to ensure that the flood carrying capacity of the watercourse is not diminished and complies with the terms of the maintenance program. The surety and the form of the bond shall be subject to the approval of the city attorney.

H.    Crawlspaces. Crawlspaces are commonly used as a method of elevating buildings to or above the base flood elevation or providing area for easier access to utilities and other building facilities. The following requirements apply to all crawlspaces that have enclosed areas or floors below the base flood elevation:

1.    The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effect of buoyancy. Hydrostatic loads and the effects of buoyancy can usually be addressed through the required opening standards set forth below in this section. If crawlspace construction is proposed for areas in which the flood velocities exceed five feet per second, the design must be reviewed and approved by a registered architect or engineer.

2.    The crawlspace is an enclosed area below the base flood elevation, and as such, must have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. Openings or vents must meet the following criteria:

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

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

3.    All portions of the building below the base flood elevation must be constructed with materials resistant to flood damage. The recommended construction practice is to elevate the bottom of the joists and all insulation above the base flood elevation.

4.    Any building utility systems within the crawlspace must be elevated above the base flood elevation or designed so that floodwaters cannot enter or accumulate within the system components. Duct work must either be placed above the base flood elevation or sealed from floodwaters.

5.    In addition to the above requirements, the following specific provisions also apply to below grade crawlspaces:

a.    The interior grade of a crawlspace below the base flood elevation must not be more than two feet below the lowest adjacent exterior grade;

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

c.    There must be an adequate drainage system that removes floodwaters from the interior area of the crawlspace. Possible options include natural drainage through porous, well-drained soils or drainage systems such as perforated pipes, tiles, gravel or other means; and

d.    Below grade crawlspace construction in accordance with the requirements listed above will not be considered basements. [Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.060 Performance standards – Areas of shallow flooding.

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

A.    Residential Structures. New construction and substantial improvements of residential structures and manufactured homes within AO zones identified in the flood insurance study and maps referenced in ECC 15.630.010(A) shall have the lowest floor (including basement) elevated above the highest adjacent grade of the building site to one foot above the depth number specified in feet on the flood insurance map or at least two feet if no depth number is specified.

B.    Nonresidential Structures. New construction and substantial improvements of nonresidential structures within such AO zones shall either:

1.    Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site to an height totaling one foot higher than the depth number specified in feet on the flood insurance map or at least two feet if no depth number is specified; or

2.    Together with attendant utility and sanitary facilities, be completely floodproofed one foot above the depth number specified in the flood insurance map(s) referenced in ECC 15.630.010(A) so that any space below that depth number 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 as in ECC 15.630.040(G), Floodproofing.

C.    Drainage Paths. All development shall include adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures.

D.    Recreational Vehicles. Recreational vehicles placed on sites within AO zones on the flood insurance map(s) shall either:

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

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

3.    Must meet the requirements of this section and the anchoring requirements for manufactured homes. [Ord. 4803 § 7, 2018; Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.070 Prohibited uses and activities.

A.    Critical Facilities. Construction of new critical facilities shall be permissible within frequently flooded areas if no feasible alternative site is available. Critical facilities constructed within frequently flooded areas shall have the lowest floor elevated three feet or more above the level of the base flood elevation (100-year flood). 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 flood elevation shall be provided to all critical facilities to the extent possible.

If not otherwise required by the city, locating of critical facilities within a frequently flooded area shall be subject to SEPA review and action.

B.    Construction in Floodways.

1.    New construction requires certification by a licensed professional engineer. Encroachments, including new construction, substantial improvements, fill, and other development, are prohibited within designated floodways unless certified by a registered professional engineer. Such certification shall demonstrate through hydrologic and hydraulic analyses, performed in accordance with standard engineering practice, that the proposed encroachment will not result in any increase in flood levels during the occurrence of the base flood discharge. Small projects that are solely to protect or create fish habitat and designed by a qualified professional may be allowed without certification if the director determines that the project will not obstruct flood flows. Fish protection projects shall be reviewed on behalf of the city by a qualified professional in the field of hydraulics.

2.    Residential Construction and Reconstruction Prohibited. Construction and reconstruction of residential structures is prohibited within designated floodways, except for:

a.    Repairs, reconstruction, or improvements to a structure that do not increase the ground floor area; and

b.    Repairs, reconstruction or improvements to a structure, for which the cost 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.

Improvement to a structure to correct existing violations of state or local health, sanitary, or safety code specifications that have been identified by the local code enforcement official and that are the minimum necessary to assure safe living conditions or to structures identified as historic places may be excluded from the calculation of the 50 percent.

3.    If the provisions of subsection (B)(2) of this section are satisfied, all new construction and substantial improvements shall comply with all applicable requirements of ECC 15.630.040 and 15.630.050. [Ord. 4656 § 1 (Exh. O2), 2013.]