Chapter 15.630
FREQUENTLY FLOODED AREAS

Sections:

15.630.010    Designation of frequently flooded areas.

15.630.015    Designation of the floodplain administrator – Permit review.

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 Administrator in a scientific and engineering report entitled “The Flood Insurance Study (FIS) for Kittitas County, Washington and Incorporated Areas,” dated September 24, 2021, and any revisions thereto, with accompanying flood insurance rate maps (FIRMs), and any revisions thereto, are hereby adopted by reference and declared to be a part of this chapter. The FIS and FIRMs are on file with the Ellensburg community development department, located at 501 N. Anderson Street in Ellensburg, Washington. The best available information for flood hazard area identification as outlined in subsection (D) of this section shall be the basis for regulation until a new FIRM is issued that incorporates data utilized under subsection (D) of this section.

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.    Compliance. All development within special flood hazard areas is subject to terms of this chapter and other applicable regulations.

D.    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.

E.    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.

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

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

H.    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.

I.    Penalties for Noncompliance. 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. Violations of the provisions of this chapter by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions), shall constitute a misdemeanor. Any person who violates this chapter or fails to comply with any of its requirements shall upon conviction thereof be fined not more than $1,000 or imprisoned for not more than 90 days, or both, for each violation, and in addition shall pay all costs and expenses involved in the case. Nothing herein contained shall prevent the city from taking such other lawful action as is necessary to prevent or remedy any violation.

J.    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 section of the city code, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.

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

1.    Considered as minimum requirements;

2.    Liberally construed in favor of the governing body; and

3.    Deemed neither to limit nor repeal any other powers granted under state statutes. [Ord. 4878 § 24, 2021; Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.015 Designation of the floodplain administrator – Permit review.

A.    The director is hereby appointed as the floodplain administrator to administer, implement, and enforce this chapter by granting or denying development permits in accordance with its provisions. The floodplain administrator may delegate authority to implement these provisions. The duties of the floodplain administrator shall include, but not be limited to:

B.    Permit Review. Review all development permits to determine that:

1.    The permit requirements of this chapter have been satisfied;

2.    All other required state and federal permits have been obtained;

3.    The site is reasonably safe from flooding;

4.    The proposed development is not located in the floodway. If located in the floodway, assure the encroachment provisions of ECC 15.630.070(B)(1) are met;

5.    Notify FEMA when annexations occur in the special flood hazard area; and

6.    Notify FEMA of changes to the base flood elevation within six months of when technical information of such changes becomes available. Such notification shall include technical or scientific information.

C.    Information to Be Obtained and Maintained.

1.    Where base flood elevation data is provided through the FIS, FIRM, or required as in ECC 15.630.040(D), obtain and maintain a record of the actual (as-built) 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 nonresidential structures where base flood elevation data is provided through the FIS, FIRM, or as required in ECC 15.630.040(D):

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

b.    Maintain the floodproofing certifications required in ECC 15.630.020(C)(2).

3.    Certification required by ECC 15.630.070(B)(1), floodway encroachments.

4.    Records of all variance actions, including justification for their issuance.

5.    Improvement and damage calculations.

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

D.    Whenever a watercourse is to be altered or relocated:

1.    Notify adjacent communities and the Department of Ecology prior to such alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administrator through appropriate notification means; and

2.    Assure that the flood carrying capacity of the altered or relocated portion of said watercourse is maintained.

E.    Interpretation of FIRM Boundaries. Make interpretations where needed, as to exact location of the boundaries of the areas of special flood hazards (e.g., 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. Such appeals shall be granted consistent with the standards of Section 60.6 of the Rules and Regulations of the NFIP (44 CFR 59-76). [Ord. 4878 § 25, 2021.]

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, 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;

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

e.    Elevation in relation to mean sea 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(H), 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. 4878 § 26, 2021; 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 Administrator, for any flood damage that results from reliance on this chapter or any administrative decision lawfully made hereunder. [Ord. 4878 § 27, 2021; 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. The permit shall be for all structures including manufactured homes, as set forth in Chapter 15.130 ECC, Definitions, and for all development including fill and other activities, also set forth in Chapter 15.130 ECC, Definitions.

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.    AE Zones with Base Flood Elevations but No Floodways. In areas with BFEs (when a regulatory floodway has not been designated), no new construction, substantial improvements, or other development (including fill) shall be permitted within zone AE on the city’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 city.

F.    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. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the 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. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

G.    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.

H.    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).

I.    Anchoring.

1.    Anchoring Required. All new construction and substantial improvements within the floodplain, including those related to manufactured homes, shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads including the effects of buoyancy.

2.    Manufactured Homes Shall Be Anchored. All manufactured homes to be placed or substantially improved within the floodplain 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 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.

J.    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.

K.    Storage of Materials and Equipment.

1.    The storage or processing of materials that could be injurious to human, animal, or plant life if released due to damage from flooding is prohibited in special flood hazard areas.

2.    Storage of other material or equipment may be allowed if not subject to damage by floods and if firmly anchored to prevent flotation, or if readily removable from the area within the time available after flood warning. [Ord. 4878 § 28, 2021; Ord. 4803 § 7, 2018; Ord. 4656 § 1 (Exh. O2), 2013.]

15.630.050 Performance standards – Specific uses.

In all frequently flooded areas where base flood elevation data has been provided as set forth in ECC 15.630.010(A) or 15.630.040(D), the following standards are required:

A.    Residential Construction.

1.    In AE 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 base flood elevation for the area. Mechanical equipment and utilities shall be waterproofed or elevated at least one foot above the BFE.

2.    New construction and substantial improvement of any residential structure in an AO zone shall meet the requirements in ECC 15.630.060.

3.    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 must meet or exceed the following minimum criteria:

a.    Have a minimum of two openings with a total net area of not less than one square inch for every square foot of enclosed area subject to flooding.

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

c.    Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, that they permit the entry and exit of floodwater.

d.    A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters.

Alternatively, a registered engineer or architect may design and certify engineered openings.

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. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet the requirements of subsection (D)(1) or (2) of this section.

1.    New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:

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 commercial, industrial, or other nonresidential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE, or elevated as required by ASCE 24, whichever is greater. Mechanical equipment and utilities shall be waterproofed or elevated at least one foot above the BFE, or as required by ASCE 24, whichever is greater.

b.    If located in an AO zone, the structure shall meet the requirements in ECC 15.630.060.

c.    If located in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained, the structure shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

d.    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:

i.    Have a minimum of two openings with a total net area of not less than one square inch for every square foot of enclosed area subject to flooding.

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

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

iv.    A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters.

Alternatively, a registered engineer or architect may design and certify engineered openings.

2.    If the requirements of subsection (D)(1) of this section are not met, then new construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:

a.    Be dry floodproofed so that below one foot or more 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 ECC 15.630.015(B)(2);

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

(Applicants who are 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.)

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, whichever is the lesser.

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.

I.    Enclosed Area Below the Lowest Floor. If buildings or manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage.

J.    Appurtenant Structures (Detached Garages and Small Storage Structures) in A Zones (A, AE, AH, AO).

1.    Appurtenant structures used solely for parking of vehicles or limited storage may be constructed such that the floor is below the BFE, provided the structure is designed and constructed in accordance with the following requirements:

a.    Use of the appurtenant structure must be limited to parking of vehicles or limited storage;

b.    The portions of the appurtenant structure located below the BFE must be built using flood-resistant materials;

c.    The appurtenant structure must be adequately anchored to prevent flotation, collapse, and lateral movement;

d.    Any machinery or equipment servicing the appurtenant structure must be elevated or floodproofed to or above the BFE;

e.    The appurtenant structure must comply with floodway encroachment provisions in ECC 15.630.070(B)(1);

f.    The appurtenant structure must be designed to allow for the automatic entry and exit of floodwaters in accordance with subsection (A)(3) of this section;

g.    The structure shall have low damage potential;

h.    If the structure is converted to another use, it must be brought into full compliance with the standards governing such use; and

i.    The structure shall not be used for human habitation.

2.    Detached garages, storage structures, and other appurtenant structures not meeting the above standards must be constructed in accordance with all applicable standards in subsection (A) of this section.

3.    Upon completion of the structure, certification that the requirements of this section have been satisfied shall be provided to the floodplain administrator for verification. [Ord. 4878 § 29, 2021; 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(H), 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) or to the height of the 500-year flood, whichever is higher. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters. 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. Located within areas of special flood hazard established in ECC 15.630.010(A) are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters that can carry debris, and increase erosion potential, the following provisions apply:

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.    Substantially Damaged Residences in Floodway.

a.    For all substantially damaged residential structures, other than farmhouses, located in a designated floodway, the floodplain administrator may make a written request that the Department of Ecology assess the risk of harm to life and property posed by the specific conditions of the floodway. Based on analysis of depth, velocity, flood-related erosion, channel migration, debris load potential, and flood warning capability, the Department of Ecology may exercise best professional judgment in recommending to the local permitting authority repair, replacement, or relocation of a substantially damaged structure consistent with WAC 173-158-076. The property owner shall be responsible for submitting to the local government and the Department of Ecology any information necessary to complete the assessment. Without a favorable recommendation from the Department for the repair or replacement of a substantially damaged residential structure located in the regulatory floodway, no repair or replacement is allowed per WAC 173-158-070(1); and

b.    Before the repair, replacement, or reconstruction is started, all requirements of the NFIP, the state requirements adopted pursuant to Chapter 86.16 RCW, and all applicable local regulations must be satisfied. In addition, the following conditions must be met:

i.     There is no potential safe building location for the replacement residential structure on the same property outside the regulatory floodway.

ii.    A replacement residential structure is a residential structure built as a substitute for a legally existing residential structure of equivalent use and size.

iii.    Repairs, reconstruction, or replacement of a residential structure shall not increase the total square footage of floodway encroachment.

iv.    The elevation of the lowest floor of the substantially damaged or replacement residential structure is a minimum of one foot higher than the BFE.

v.    New and replacement water supply systems are designed to eliminate or minimize infiltration of floodwater into the system.

vi.    New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of floodwater into the system and discharge from the system into the floodwaters.

vii.    All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage.

4.    If the provisions of subsection (B)(1) of this section are satisfied, or construction is allowed pursuant to subsection (B)(2) or (B)(3) of this section, all new construction and substantial improvements shall comply with all applicable requirements of ECC 15.630.040 and 15.630.050.

C.    Livestock Sanctuary Areas. Elevated areas for the purpose of creating a flood sanctuary for livestock are allowed on farm units where livestock is allowed. Livestock flood sanctuaries shall be sized appropriately for the expected number of livestock and be elevated sufficiently to protect livestock. Proposals for livestock flood sanctuaries shall meet all procedural and substantive requirements of this chapter. [Ord. 4878 § 30, 2021; Ord. 4656 § 1 (Exh. O2), 2013.]