Chapter 18.40
FREQUENTLY FLOODED AREAS
Sections:
Article I. Designation
18.40.010 Designation of frequently flooded areas.
Article II. Critical Area Report Requirements – Frequently Flooded Areas
18.40.020 Critical area report – Additional requirements.
Article III. Performance Standards – Frequently Flooded Areas
18.40.030 Performance standards – General requirements.
Article IV. Prohibited Uses and Activities
18.40.040 Uses and activities prohibited from frequently flooded areas.
Article V. Variances
18.40.050 Variances – Additional considerations for frequently flooded areas.
Article I. Designation
18.40.010 Designation of frequently flooded areas.
A. Frequently Flooded Areas. Frequently flooded areas shall include:
1. Areas Identified on the Flood Insurance Rate Map(s). Those areas of special flood hazard identified by the Federal Insurance Administration in a scientific and engineering report titled “The Flood Insurance Study for Snohomish County, Washington and Incorporated Areas dated June 19, 2020,” with an accompanying flood insurance rate map(s), and any revisions thereto. The Flood Insurance Study and accompanying map(s) are hereby adopted by reference, declared part of this title, and are available for public review at the city.
2. Areas Identified by the Director. Those areas of special flood hazard identified by the director based on review of base flood elevation and floodway data available from federal, state, county, or other valid sources when base flood elevation data has not been provided from the Federal Insurance Administration (A and V zones of the flood insurance map(s)).
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. Elevation Certificate May Be Required. The director may request an elevation certificate to determine if a property, in whole or part, is within a flood hazard area. A surveyor or engineer licensed in the state of Washington shall complete the FEMA form elevation certificate and submit it to the city for recording.
D. Flood Elevation Data. When base flood elevation data is not available (A and V zones), the director 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 this title.
E. Designation Made by Director. The flood insurance maps are to be used as a guide for the city/county, project applicants and/or property owners, and the public, and should be considered a minimum designation of frequently flooded areas. As flood insurance maps may be continuously updated as areas are reexamined or new areas are identified, newer and more restrictive information for flood hazard area identification shall be the basis for regulation.
F. Maintenance of Records.
1. Where base flood elevation data is provided through the FIS, FIRM, or as required in BMC 15.28.150(B), the director shall obtain and maintain a record of the 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 BMC 15.28.150(B):
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 BMC 15.28.130(C).
3. Records of all variance action, including justification for their issuance.
4. Improvement and damage calculations.
5. Maintain for public inspection all records pertaining to the provisions of this chapter. (Ord. 465 § 2 (Exh. B), 2020; Ord. 389 § 1 (Exh. A) (part), 2011)
Article II. Critical Area Report Requirements – Frequently Flooded Areas
18.40.020 Critical area report – Additional requirements.
In addition to the general critical area report requirements of BMC 18.10.160, critical area reports for frequently flooded areas must meet the requirements of this section.
A. 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 (one-hundred-year flood elevation), ten- and fifty-year flood elevations, floodway, 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. Clearing limits; and
d. Elevation of the lowest floor (including basement) of all structures, and the level to which any nonresidential structure has been floodproofed.
2. 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 proposal.
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.
c. Compliance Documentation. Information describing and documenting how the proposed water course alteration complies with the requirements of Chapter 18.70 BMC, Fish and Wildlife Habitat Conservation Areas, the Brier Shoreline Management Program and other applicable state or federal permit requirements. (Ord. 465 § 2 (Exh. B), 2020; Ord. 389 § 1 (Exh. A) (part), 2011)
Article III. Performance Standards – Frequently Flooded Areas
18.40.030 Performance standards – General requirements.
The following standards shall be adhered to in all frequently flooded areas, except as otherwise provided for in this title.
A. Development Permit Required. A development permit shall be obtained before land is altered or a new use is commenced within a frequently flooded area. For application of this title, development shall include any manmade alteration to land, including but not limited to buildings, structures, mining, dredging, filling, grading, paving, excavation, drilling operations, or storage of equipment or materials within the area of special flood hazard.
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 Section 404 of the Federal Water Pollution Control Act Amendment of 1972 and the Endangered Species Act of 1973.
C. Areas without Base Flood Elevation Data. Where base flood elevation data is not available (A and V zones), and there is insufficient data available from federal, state, or other sources, the applicant shall provide a flood elevation certificate to determine the base flood elevation. 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.
D. Fill and Grading. There shall be no fill and grading within the floodplain except as necessary to maintain existing utilities that cannot be relocated outside of a floodplain. Fill and grading shall be done in accordance with an approved critical area report that requires mitigation for all unavoidable impacts.
E. Utilities.
1. Shall Be Designed to Minimize Infiltration of Flood Waters. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the systems.
2. Sanitary Sewage Systems. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharges from the systems into flood waters.
3. On-Site Waste Disposal Systems. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. New on-site sewage disposal systems are prohibited pursuant to uses and activities prohibited from frequently flooded areas in BMC 18.40.040(C).
F. Alteration of Watercourses.
1. Shall Be in Accordance with Habitat Regulations. Watercourse alterations shall only be allowed in accordance with the requirements of Chapter 18.70 BMC, relating to fish and wildlife habitat conservation areas.
2. Notification Required. The city shall notify adjacent communities, the State Department of Ecology, the Washington Department of Fish and Wildlife, the affected tribes, and the Federal Insurance Administration of the proposed watercourse alteration at least thirty days prior to permit issuance.
3. 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. Maintenance shall be bonded for a period of five years, and be in accordance with an approved maintenance program. (Ord. 465 § 2 (Exh. B), 2020; Ord. 389 § 1 (Exh. A) (part), 2011)
Article IV. Prohibited Uses and Activities
18.40.040 Uses and activities prohibited from frequently flooded areas.
A. Critical Facilities. Critical facilities are prohibited from frequently flooded areas unless no feasible alternative site is available.
B. Wells Used for Potable Water. Water wells are prohibited from the floodway.
C. On-Site Sewage Disposal Systems. On-site sewage disposal systems are prohibited from the floodway, the channel migration zone, and the ten-year floodplain elevation.
D. Construction in Floodways.
1. New Construction Requires Certification by an Engineer. Encroachments, including new construction, substantial improvements, fill, and other development, are prohibited within frequently flooded areas unless certified by a registered professional engineer with experience in hydrology and the preparation of hydrogeologic assessments. 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.
2. Residential Construction and Reconstruction Prohibited. Construction and reconstruction of residential structures is prohibited within frequently flooded areas, except for:
a. Repairs, reconstruction, or improvements to a structure that do not increase the ground floor area.
b. Repairs, reconstruction or improvements to a structure, for which the cost does not exceed fifty 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 city code enforcement official and that are the minimum necessary to assure safe living conditions or to structures identified as historic places shall not be included in the fifty percent. (Ord. 465.A § 1 (Exh. A), 2020; Ord. 465 § 2 (Exh. B), 2020; Ord. 389 § 1 (Exh. A) (part), 2011)
Article V. Variances
18.40.050 Variances – Additional considerations for frequently flooded areas.
A. Additional Variance Considerations. In review of variance requests for activities within frequently flooded areas, the planning commission and the city council shall consider all technical evaluations, relevant factors, standards specified in this title, and:
1. The danger to life and property due to flooding, erosion damage, or materials swept onto other lands during flood events.
2. The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the proposed use.
3. The importance of the services provided by the proposed use to the community.
4. The necessity to the proposed use of a waterfront location, where applicable, and the availability of alternative locations for the proposed use that are not subject to flooding or erosion damage.
5. The safety of access to the property in times of flood for ordinary and emergency vehicles.
6. The expected heights, velocity, duration, rate of rise, and sediment transport of the flood waters and the effects of wave action, if applicable, expected at the site.
7. 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.
8. The compatibility of the proposed use with existing and anticipated development.
9. The relationship of the proposed use to the comprehensive plan and floodplain management program for that area.
B. Variances shall only be issued:
1. Upon a determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public, or conflict with existing laws or ordinances.
2. For the repair, rehabilitation, or restoration of historic structures upon a determination that the proposed repair or rehabilitation will not preclude the structure’s continued designation as a historic structure and the variance is the minimum necessary to preserve the historic character and design of the structure.
3. Upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.
4. Upon a showing of good and sufficient cause.
5. Upon a determination that the failure to grant the variance would result in exceptional hardship to the applicant.
6. Upon a showing that the use cannot perform its intended purpose unless it is located or carried out in close proximity to water. This includes only facilities defined in BMC 15.28.050 in the definition of “functionally dependent use.”
C. Variances shall not be issued within a floodway if any increase in flood levels during the base flood discharge would result.
D. Any applicant to whom a variance is granted shall be given written notice over the signature of a community official that:
1. The issuance of a variance to construct a structure below the BFE will result in increased premium rates for flood insurance up to amounts as high as twenty-five dollars for one hundred dollars of insurance coverage; and
2. Such construction below the BFE increases risks to life and property. (Ord. 465 § 2 (Exh. B), 2020; Ord. 389 § 1 (Exh. A) (part), 2011)