Chapter 14.80
FLOOD HAZARD AREAS
Sections:
14.80.010 Purpose and applicability.
14.80.011 Abrogation and greater restrictions.
14.80.013 Methods of reducing flood losses.
14.80.014 Designation of the floodplain administrator.
14.80.015 Duties and responsibilities of the floodplain administrator.
14.80.020 Basis for establishing the areas of special flood hazard.
14.80.040 Additional special flood hazard areas.
14.80.045 Establishment of development permit.
14.80.050 Flood hazard area review procedures.
14.80.060 Provisions for flood hazard reduction.
14.80.070 Variances to flood hazard areas.
14.80.075 Penalties for noncompliance.
14.80.010 Purpose and applicability.
The purpose of this chapter is to promote the public health, safety, and general welfare of the citizens of Edgewood, thereby reducing the annual cost of flood insurance. This chapter shall apply to all special flood hazard areas within the boundaries of the city of Edgewood.
The standards contained in this chapter are intended to minimize public and private losses due to flood conditions in specific areas, and provide special criteria necessary for regulated activities located within said areas, by provisions designed to:
A. Protect human life and health;
B. Minimize expenditure of public money for costly flood control projects;
C. Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;
D. Minimize prolonged business interruptions;
E. Minimize damage to public infrastructure, facilities and utilities, such as water and gas mains; electric, telephone, and sewer lines; and streets and bridges located in flood hazard areas;
F. Minimize damage to critical fish and wildlife habitat areas;
G. Minimize net loss of ecological functions of floodplains;
H. Notify potential buyers that property is in a special flood hazard area;
I. Notify those who occupy flood hazard areas that they assume responsibility for their actions;
J. Qualify Edgewood for participation in the National Flood Insurance Program, thereby giving the citizens of Edgewood the opportunity to purchase flood insurance, with particular emphasis to those in flood hazard areas, and maintain eligibility for disaster relief; and
K. Help maintain a stable tax base by providing for the sound use and development of flood hazard areas so as to minimize blight areas caused by flooding. (Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).
14.80.011 Abrogation and greater restrictions.
This chapter is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this chapter and another ordinance, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail. (Ord. 20-589 § 1 (Exh. A)).
14.80.012 Interpretation.
In the interpretation and application of this chapter, all provisions shall be:
A. Considered as minimum requirements;
B. Liberally construed in favor of the governing body; and
C. Deemed neither to limit nor repeal any other powers granted under state statutes. (Ord. 20-589 § 1 (Exh. A)).
14.80.013 Methods of reducing flood losses.
In order to accomplish its purposes, this chapter includes methods and provisions for:
A. Restricting or prohibiting development that is dangerous to health, safety, and property due to water or erosion hazards, or which result in damaging increases in erosion or in flood heights or velocities;
B. Requiring that development vulnerable to floods be protected against flood damage at the time of initial construction;
C. Controlling the alteration of natural floodplains, stream channels, and natural protective barriers, which help accommodate or channel flood waters;
D. Controlling filling, grading, dredging, or other development which may increase flood damage; and
E. Preventing or regulating the construction of flood barriers that unnaturally divert floodwaters or may increase flood hazards in other areas. (Ord. 20-589 § 1 (Exh. A)).
14.80.014 Designation of the floodplain administrator.
The public works director is hereby appointed as the Edgewood 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. (Ord. 20-589 § 1 (Exh. A)).
14.80.015 Duties and responsibilities of the floodplain administrator.
Duties of the floodplain administrator shall include, but not be limited to:
A. 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 that the encroachment provisions of EMC 14.80.060(C) are met; and
5. Notify FEMA when annexations occur in the special flood hazard area.
B. Use of Other Base Flood Data (in A Zones). When base flood elevation data has not been provided (in A zones), the floodplain 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 EMC 14.80.060(B), Specific Standards, and 14.80.060(C), Floodways.
C. Information to Be Obtained and Maintained.
1. Where base flood elevation data is provided through the FIS, FIRM, or as required in subsection (B) of this section, 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 subsection (B) of this section:
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 EMC 14.80.045(B)(3).
3. Certification required by EMC 14.80.050(E) or 14.80.060(C)(1).
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. Alteration of Watercourse. 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.
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.
F. Review of Building Permits. Where elevation data is not available either through the FIS, FIRM, or from another authoritative source (subsection (B) of this section, Use of Other Base Flood Data (in A Zones)), applications for floodplain development shall be reviewed to assure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. Failure to elevate habitable buildings at least two feet above the highest adjacent grade in these zones may result in higher insurance rates.
G. Changes to Special Flood Hazard Area.
1. If a project will alter the BFE or boundaries of the SFHA, then the project proponent shall provide the community with engineering documentation and analysis regarding the proposed change. If the change to the BFE or boundaries of the SFHA would normally require a letter of map change, then the project proponent shall initiate, and receive approval of, a conditional letter of map revision (CLOMR) prior to approval of the development permit. The project shall be constructed in a manner consistent with the approved CLOMR.
2. If a CLOMR application is made, then the project proponent shall also supply the full CLOMR documentation package to the floodplain administrator to be attached to the floodplain development permit, including all required property owner notifications. (Ord. 20-589 § 1 (Exh. A)).
14.80.020 Basis for establishing the areas of special flood hazard.
The special flood hazard areas identified by the Federal Insurance Administrator in a scientific and engineering report entitled “The Flood Insurance Study for Pierce County, Washington and Incorporated Areas,” dated March 7, 2017, with accompanying FIRMs dated March 7, 2017, and any revisions thereto, are hereby adopted and incorporated herein by reference. The FIS and FIRMs are on file at Edgewood City Hall, 2224 104th Avenue East, Edgewood, Washington, 98371. The best available information for flood hazard area identification as outlined in EMC 14.80.015(B) shall be the basis for regulation until a new FIRM is issued that incorporates data utilized under EMC 14.80.015(B).
In addition, for the purposes of this title, the city of Edgewood may regulate those areas listed under EMC 14.80.040 as special flood hazard areas. (Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).
14.80.030 Definitions.
A. Refer to Chapter 14.20 EMC for definitions of any word or phrase not otherwise contained herein. For this chapter the definitions listed below shall apply:
1. “Alteration of watercourse” means any action that will change the location of the channel occupied by water within the banks of any portion of a riverine waterbody.
2. “Appeal” means a request for a review of the interpretation of any provision of this chapter, per EMC 14.10.110, or request for a flood hazard area variance per EMC 14.80.070.
3. “Area of shallow flooding” means a designated zone AO, AH, AR/AO or AR/AH on a community’s Flood Insurance Rate Map (FIRM) with a one percent or greater annual chance of flooding to an average depth of one to three feet where a clearly defined channel does not exist, where the path of flooding is unpredictable, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow. Also referred to as the sheet flow area.
4. “Area of special flood hazard” means the land in the floodplain within a community subject to a one percent or greater chance of flooding in any given year. It is shown on the Flood Insurance Rate Map (FIRM) as zone A, AO, AH, A1-30, AE, A99, or AR. “Special flood hazard area” is synonymous in meaning with the phrase “area of special flood hazard.”
5. “ASCE 24” means the most recently published version of ASCE 24, Flood Resistant Design and Construction, published by the American Society of Civil Engineers.
6. “Base flood” has the same meaning as defined in Chapter 14.20 EMC.
7. “Base flood elevation,” or “BFE,” means the elevation to which floodwater is anticipated to rise during the base flood.
8. “Basement” means any area of the building having its floor subgrade (below ground level) on all sides, for the purposes of this title.
9. “Breakaway wall” means a wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces, without causing damage to the elevated portion of the building or supporting foundation system.
10. “Building” shall have the same meaning as “structure” in this section.
11. “Building code” means the currently effective versions of the International Building Code and the International Residential Code adopted by the State of Washington Building Code Council, as adopted under EMC Title 15.
12. Critical Facilities. See EMC 14.20.010(B)(22). For floodplain management purposes, “essential facilities” as defined herein, and “essential public facilities” as defined under EMC 18.20.080 and 18.100.050, are considered critical facilities.
13. “Development” means any human-induced change to improved or unimproved real estate, including but not limited to: the construction of buildings or other structures, placement of a manufactured home/mobile home, mining, dredging, clearing, filling, grading, paving, excavation, drilling operations, storage of equipment or materials located within an area of special flood hazard, or activities otherwise governed by EMC Title 16, Subdivisions.
14. “Elevated building” means a nonbasement building that has its lowest elevated floor raised above ground level by foundation walls, shear walls, posts, piers, pilings, or columns.
15. “Essential facility” means the same thing as “essential facility” defined in ASCE 24. Table 1-1 in ASCE further identifies building occupancies that are essential facilities.
16. “Existing manufactured home park or subdivision” means a manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is completed before the effective date of the floodplain management regulations adopted by the community.
17. “Expansion to an existing manufactured home park or subdivision” means the preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads).
18. “Flood” or “flooding” means:
a. A general and temporary condition of partial or complete inundation of normally dry land areas from:
i. The overflow of inland or tidal waters; or
ii. The unusual and rapid accumulation of runoff of surface waters from any source; or
iii. Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in subsection (a)(ii) of this definition and are akin to a river of liquid and flowing mud on the surfaces of normally dry land areas, as when earth is carried by a current of water and deposited along the path of the current.
b. The collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding as defined in subsection (a) of this definition.
19. “Flood elevation study” means an examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards. Also known as a flood insurance study (FIS).
20. “Flood Insurance Rate Map” or “FIRM” has the same meaning as defined in Chapter 14.20 EMC. A FIRM that has been made available digitally is called a Digital Flood Insurance Rate Map (DFIRM).
21. “Flood elevation study” means an examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards. Also known as a flood insurance study (FIS).
22. “Floodplain” or “flood-prone area” means any land area susceptible to being inundated by water from any source. See “flood” or “flooding.”
23. “Floodplain administrator” means the community official designated by this chapter to administer and enforce the floodplain management regulations.
24. “Floodproofing” means any combination of structural and nonstructural additions, changes, or adjustments to structures which reduce or eliminate risk of flood damage to real estate or improved real property, water and sanitary facilities, structures, and their contents. Floodproofed structures are those that have the structural integrity and design to be impervious to floodwater below the base flood elevation.
25. “Floodway” has the same meaning as defined in Chapter 14.20 EMC. Also referred to as “regulatory floodway.”
26. “Highest adjacent grade” means the highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.
27. “Historic structure” means any structure that is:
a. Listed individually in the National Register of Historic Places (a listing maintained by the Department of the Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;
b. Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;
c. Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or
d. Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:
i. By an approved state program as determined by the Secretary of the Interior, or
ii. Directly by the Secretary of the Interior in states without approved programs.
28. “Increased cost of compliance (ICC)” means a flood insurance claim payment up to $30,000 directly to a property owner for the cost to comply with floodplain management regulations after a direct physical loss caused by a flood. Eligibility for an ICC claim can be through a single instance of substantial damage or as a result of cumulative substantial damage. (More information can be found in FEMA ICC Manual 301.)
29. “Lowest floor” has the same meaning as defined in Chapter 14.20 EMC.
30. “Manufactured home or mobile home” means a structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when connected to the required utilities. For floodplain management purposes, the term “manufactured home or mobile home” also includes park trailers, travel trailers, and other similar recreational vehicles placed on a site for greater than 180 consecutive days. For insurance purposes, the term “manufactured home or mobile home” does not include park trailers, travel trailers, recreational vehicles, or other similar vehicles.
31. “Manufactured home park or subdivision” means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
32. “Mean sea level” means, for purposes of the National Flood Insurance Program, the vertical datum to which base flood elevations shown on a community’s Flood Insurance Rate Map are referenced.
33. “New construction” means structures for which the start of construction commenced on or after the following:
a. For the purposes of determining flood insurance rates, the effective date of an initial FIRM (i.e., August 19, 1987, or specifically for Panel 350, August 4, 1988), and includes any subsequent improvements to such structures.
b. For floodplain management purposes, December 15, 2020 (the effective date of the ordinance codified in this chapter), including any subsequent improvements to such structures.
34. “New manufactured home park or subdivision” means a manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is completed on or after December 15, 2020 (the effective date of the ordinance codified in this chapter).
35. “Reasonably safe from flooding” means development that is designed and built to be safe from flooding based on consideration of current flood elevation studies, historical data, high water marks and other reliable data known to the community. In unnumbered A zones where flood elevation information is not available and cannot be obtained by practicable means, “reasonably safe from flooding” means that the lowest floor is at least two feet above the highest adjacent grade.
36. “Recreational vehicle (RV)” means a vehicle built on a single chassis, 400 square feet or less when measured at the largest horizontal projection, designed to be self-propelled or permanently towable by a light duty truck, and designed primarily not for use as a permanent dwelling but as a temporary living quarters for recreational, camping, travel, or seasonal use.
37. “Start of construction” includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement or other improvement was within 180 days of the permit date. The “actual start” means either the first placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; or the placement of a manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers, or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure. For a substantial improvement, the “actual start of construction” means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building.
38. “Structure,” for the purposes of floodplain management, means a walled and roofed building, including a gas or liquid storage tank that is principally above ground, as well as a manufactured home.
39. “Substantial damage” has the same meaning as defined in Chapter 14.20 EMC.
40. “Substantial improvement” has the same meaning as defined in Chapter 14.20 EMC.
41. “Variance” means a grant of relief from the requirements of this chapter that permits construction in a manner that would otherwise be prohibited, per EMC 14.80.070.
42. Violation. See EMC 14.20.010(B)(94). With regard to floodplain management, projects without an elevation certificate, other certifications, or other evidence of compliance required in this chapter are presumed to be in violation until such time as said documentation is provided.
43. “Water dependent” means a structure for commerce or industry that cannot exist in any other location and is dependent on the water by reason of the intrinsic nature of its operations.
44. “Water surface elevation” means the height, in relation to the vertical datum utilized in the applicable flood insurance study, of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas. (Ord. 24-660 § 14 (Exh. B); Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).
14.80.040 Additional special flood hazard areas.
In addition to those areas identified under EMC 14.80.020, the city of Edgewood may regulate the following as special flood hazard areas:
A. Potential Flood Hazard Areas. Unless otherwise approved under a development permit (EMC 14.80.045), the following areas shall be regulated as special flood hazard areas:
1. City-identified flood hazard areas as depicted on the frequently flooded areas map adopted under EMC 14.10.040(G).
2. Areas within 300 feet horizontal distance and five feet of vertical height from the base flood elevation established for mapped AE and AH zones.
3. Unstudied Areas. FEMA FIRM A zones and shaded X zones, and areas within 300 feet horizontal distance from said mapped areas.
4. Natural Waters or Watercourse. Areas within five feet of vertical height above the ordinary high water mark of an identified natural watercourse.
5. Closed Depressions. Areas not identified as a mapped flood hazard area as described above, but within 10 feet of vertical relief from the bottom of an identified closed depression or within two feet of vertical relief of a potential surface water spillway or other type of outlet. Closed depressions may be identified by city topographic mapping, field survey, or site inspections.
6. The frequently flooded areas map (EMC 14.10.040(G)) may not show all potential flood hazard areas that may be necessary for a specific site analysis. The department may make interpretations, where needed, as to the approximate location of the boundaries of potential flood hazard areas. When there is a conflict between the elevations and the mapped potential flood hazard area boundaries, the elevations shall govern. Further, where there is insufficient information shown on the potential flood hazard area maps, the department may require the applicant to verify that the site is out of the flood hazard area using the flood hazard area review procedures set forth in EMC 14.80.050.
B. Floodway. A floodway is an extremely hazardous area due to the depth and/or velocity of floodwaters which could carry debris, potential projectiles, and have erosion potential. The following areas are regulated by the city as special flood hazard areas and floodways:
1. Regulatory Floodway. Regulatory floodway designated by flood hazard area maps.
2. Deep or Fast-Flowing Water Areas. Areas of deep or fast-flowing water shall be regulated as a floodway. Based on the criteria set forth in this chapter, the department shall make the determination after review and approval of applicant’s analysis of whether the project site falls within the floodway area based on deep or fast-flowing waters.
3. Closed Depressions and Shaded X Zones. That portion of said areas that is three feet or greater in depth shall be regulated as a floodway. This includes, but is not limited to, the city-identified floodway areas as depicted on the frequently flooded areas map adopted under EMC 14.10.040(G).
C. Flood Fringe. All areas subject to inundation by the base flood, but outside the limits of the floodway as set forth in subsection (B) of this section. Those portions of the A, AE, AH, and shaded X zones not defined as floodway, and that portion of a closed depression and FEMA shaded X zone area that is between zero feet (base flood elevation) and three feet in depth (city-identified 100-year floodplain areas as depicted on the frequently flooded areas map adopted under EMC 14.10.040(G)), shall be regulated as a flood fringe.
D. Other Areas of Special Flood Hazard.
1. Groundwater Flooding Areas. Groundwater flooding areas are those areas subject to flood inundation from subsurface waters that result from a fluctuation of the groundwater table. Groundwater flooding areas shall be regulated as closed depressions per subsections (B)(3) and (C) of this section.
2. Natural Waters or Watercourses. Natural waters or watercourses as identified on city topographic, planimetric or orthophoto maps, WDNR stream classification maps, USGS quadrangle maps, or other source maps that are not identified as a flood hazard area on the FEMA maps. That portion of the natural watercourse located between the ordinary high water mark and a topographic elevation two feet above the ordinary high water mark shall be regulated as a floodway, and between two and five feet above the ordinary high water mark shall be regulated as flood fringe. If the applicant chooses to accept the five-foot topographic elevation line above the ordinary high water mark as the base flood elevation (i.e., floodplain elevation limits), a flood study shall not be required for a natural water/watercourse. (Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).
14.80.045 Establishment of development permit.
A. Development Permit Required. A development permit shall be obtained before construction or development begins within any area of special flood hazard. The permit shall be for all structures, including manufactured homes, as set forth in EMC 14.80.030, Definitions, and for all development, including fill and other activities, also as set forth in EMC 14.80.030, Definitions.
B. Application for Development Permit. Application for a development permit shall be on forms furnished by the floodplain administrator and may include, but not be limited to, plans in duplicate drawn to scale showing the nature, location, dimensions, and elevations of the area in question; existing or proposed structures, fill, storage of materials, drainage facilities, and the location of the foregoing. Specifically, the following information is required:
1. Elevation in relation to mean sea level of the lowest floor (including basement) of all structures recorded on a current elevation certificate, completed and certified by a professional land surveyor currently licensed in the state of Washington, with Section B of such certificate completed by the floodplain administrator;
2. Elevation in relation to mean sea level to which any structure has been floodproofed;
3. Where a structure is to be floodproofed, certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet floodproofing criteria in EMC 14.80.060(B)(2), Nonresidential Construction;
4. Description of the extent to which a watercourse will be altered or relocated as a result of proposed development;
5. Where development is proposed in a floodway, an engineering analysis indication of no rise of the base flood elevation; and
6. Any other such information that may be reasonably required by the floodplain administrator in order to review the application. (Ord. 20-589 § 1 (Exh. A)).
14.80.050 Flood hazard area review procedures.
A. General Requirements.
1. The city’s frequently flooded areas map (EMC 14.10.040(G)) only provides an indication of where potential flood hazard areas may be located within the city. The actual presence or location of a flood hazard area shall be determined using the procedures and criteria contained in this chapter.
2. The department will complete a review of the flood hazard area maps, and other source documents, for any development proposal to determine whether the proposed project area for a regulated activity falls within a potential flood hazard area. When there is a conflict between the elevations and the mapped 100- or 500-year floodplain or floodway boundaries, the elevations shall govern. In the instance where base flood elevation data has not been provided within a mapped A zone, the department shall obtain, review, and reasonably utilize any base flood elevation and floodway data available from a federal, state, or other source to complete their review.
3. When the department’s maps or sources indicate that the proposed project area for a regulated activity is or may be located within a potential flood hazard area, the department shall require a flood boundary verification survey as outlined in subsection (B) of this section, and may require a flood study as outlined in subsection (C) of this section, a deep or fast-flowing water analysis as outlined in subsection (D) of this section, or a zero-rise analysis as outlined in subsection (E) of this section.
4. Any proposed development located within a flood hazard area shall comply with the provisions for flood hazard reduction set forth in EMC 14.80.060.
5. Prior to city approval of any proposed flood hazard area development, any necessary permits from those governmental agencies from which prior approval is required by federal or state law, including but not limited to Section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 U.S.C. 1334, must be provided to the city by the applicant.
6. A FEMA letter of map amendment (LOMA) or letter of map revision (LOMR) shall not be submitted to FEMA until review and approval has been granted by the department. The city shall not recognize any LOMA or LOMR as an amendment to the department’s flood hazard maps unless the department has granted prior approval.
7. Unless otherwise stated in this chapter, the critical area protective measure provisions contained in EMC 14.10.070 shall apply.
8. 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 hazards or uses permitted within such areas will be free from flooding or flood damages. This chapter shall not create liability on the part of the city of Edgewood, any officer or employee thereof, or the Federal Insurance Administration, for any flood damages that result from reliance on this chapter or any administrative decision lawfully made hereunder.
B. Flood Boundary Verification Survey.
1. A flood boundary verification survey that delineates the horizontal and vertical limits of the base flood elevation shall be submitted to the department when the department’s maps or sources indicate that the proposed project area for a regulated activity is located within a potential flood hazard area.
a. Where a base flood elevation has not been established, a flood study shall be required pursuant to subsection (C) of this section.
b. A base flood elevation that has been established through a detailed flood study accepted by the department may be used in lieu of conducting a new flood study.
c. In lieu of a flood study, the base flood elevation for a natural watercourse (EMC 14.80.040(D)(2)) shall be established at the five-foot topographic elevation line above the ordinary high water mark.
2. The requirement to submit a flood boundary verification survey may be waived at the department’s discretion, when the department can determine, using contour elevations, base flood data, orthophotos, and parcel data, that the extent of the regulated activity is clearly above the base flood elevation.
3. The flood boundary verification survey shall be prepared, signed, and dated by a registered land surveyor.
4. The department shall review the flood boundary verification survey to determine if the proposed development is located within a flood hazard area.
5. If the proposed development lies within the flood hazard area, the limits of the floodway, as well as the base flood elevation, shall be shown on the flood boundary verification survey.
C. Flood Study.
1. A flood study shall be conducted when the department’s maps or sources indicate that the proposed project area for a regulated activity is, or may be located within, a potential flood hazard area where base flood elevation data is not available through the flood insurance study or other authoritative sources, or when an established base flood elevation is contested. A full engineering analysis to determine the base flood elevation shall be required by the department. Base flood elevations shall be determined using the detailed methods established in EMC 14.80.080, Appendix A. The department may approve alternative methods.
2. The flood study shall be prepared, signed, and dated by a professional engineer.
3. Once the department has reviewed and approved the flood study, the applicant shall be required to provide a flood boundary verification survey, utilizing the newly established base flood elevation, as outlined in subsection (B) of this section.
D. Deep or Fast-Flowing Water Analysis.
1. When the department determines that a proposed project area for a regulated activity is located within a flood hazard area, a deep or fast-flowing water analysis based on EMC 14.80.080, Appendix A, shall be required to determine the floodway limits.
2. The floodway limits and flood fringe limits identified in the deep and/or fast-flowing water analysis shall be depicted on the flood boundary verification survey, as outlined in subsection (B) of this section.
3. The deep and/or fast-flowing water analysis shall be prepared, signed, and dated by a professional engineer.
E. Zero-Rise Analysis.
1. When the department determines that a proposed project area for a regulated activity is located within a special flood hazard area, a zero-rise analysis shall be required to determine that no increase in base flood elevation, displacement of flood volume, or flow conveyance reduction will occur as a result of the development.
2. The zero-rise analysis shall be conducted utilizing Hydrologic Engineering Center – River Analysis System (HEC-RAS) modeling methodology for stream and channel floodways; the Western Washington Hydrology Model (WWHM) for closed depression floodways; or an alternative methodology approved by the city (see EMC 14.80.080, Appendix A). The analysis shall show that no rise has occurred as a result of the proposed development. The scope of the proposed development may need to be reduced or special engineering may be required (e.g., utilizing piers or pilings) to achieve zero rise.
3. If the zero-rise analysis is required for a project that is proposed outside of, but tributary to, a special flood hazard area, the analysis shall show that no rise greater than 0.01 foot will occur because of the proposed development (see Chapter 13.05 EMC).
4. The zero-rise analysis shall be prepared, signed, and dated by a professional engineer.
5. The zero-rise analysis shall be documented on the zero-rise analysis form, as set forth in EMC 14.80.080, Appendix A, and shall be attached to the flood hazard area permit.
6. When structures are elevated by piers or pilings and no fill is placed in the flood hazard area, the requirement to submit a zero-rise analysis may be waived at the department’s discretion. (Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).
14.80.060 Provisions for flood hazard reduction.
A. General Standards. In all areas of special flood hazard (see EMC 14.80.020 and 14.80.040), the following standards are required:
1. Anchoring.
a. All new construction and substantial improvements, 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.
b. All manufactured homes shall 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. For more detailed information, refer to guidebook FEMA-85, “Manufactured Home Installation in Flood Hazard Areas.”
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. Storage of Materials and Equipment.
a. 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.
b. 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.
4. Utilities.
a. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the systems;
b. Water wells shall be located on high ground that is not in the floodway (WAC 173-160-171) or in flood fringe areas;
c. 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;
d. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. New effluent dispersal components shall be prohibited in all special flood hazard areas, and replacement effluent dispersal components shall be prohibited in closed depression floodways and flood fringe.
5. Subdivision Proposals and Development. All new development shall:
a. Be consistent with the need to minimize flood damage;
b. Have public utilities and facilities, such as sewer, gas, electrical, and water systems, located and constructed to minimize or eliminate flood damage;
c. Have adequate drainage provided to reduce exposure to flood damage; and
d. Where subdivision proposals and other proposed developments contain greater than 50 lots or five acres (whichever is the lesser), base flood elevation data shall be included as part of the application.
6. Public Works Projects. New construction done by or for the city, such as bridges, roads, flood control works, revetments, retaining walls, drainage structures, sewer or water lines, parks, or other structures necessary to promote the public’s health, safety, and welfare, shall be allowed in a flood hazard area when:
a. The project is prepared, dated, and stamped by a registered professional engineer in the state of Washington and is designed so the project does not result in any increase in flood levels during the occurrence of the base flood discharge (zero-rise) and shall not obstruct the floodway or cause an adverse impact to critical fish or wildlife habitat or adjacent, cross-channel, or upstream or downstream properties; and
b. The improvements utilize applicable flood hazard reduction provisions.
B. Specific Standards. In all areas of special flood hazards where base flood elevation data has been provided as set forth in EMC 14.80.015(B) or 14.80.020, including but not limited to flood fringe areas (EMC 14.80.040(C)), the following provisions are required:
1. Residential Construction.
a. In AE and A1-30 zones and 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 two feet or more above the BFE. Mechanical equipment and utilities shall be waterproof or elevated at least two feet above the BFE.
b. New construction and substantial improvement of any residential structure in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.
c. 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:
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; and
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 flood waters.
Alternatively, a registered engineer or architect may design and certify engineered openings.
2. Nonresidential Construction. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet the requirements of subsection (B)(2)(a) or (b) of this section.
a. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:
i. 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 two feet 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 two feet above the BFE, or as required by ASCE 24, whichever is greater.
ii. 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.
iii. 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:
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 automatic entry and exit of floodwater.
b. If the requirements of subsection (B)(2)(a) 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:
i. Be dry floodproofed so that below two feet 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;
ii. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
iii. 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 EMC 14.80.015(C)(2); and
iv. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in EMC 14.80.060(B)(1)(c).
3. Manufactured Homes.
a. All manufactured homes 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 two feet or more above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
4. Recreational Vehicles.
a. Recreational vehicles placed on sites are required to either:
i. Be on the site for fewer than 180 consecutive days; or
ii. 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
iii. Meet the requirements of subsection (B)(3) of this section.
5. 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.
6. Appurtenant Structures (Detached Garages and Small Storage Structures) for A Zones (A, AE, A1-30, AH, AO):
a. 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:
i. Use of the appurtenant structure must be limited to parking of vehicles or limited storage;
ii. The portions of the appurtenant structure located below the BFE must be built using flood-resistant materials;
iii. The appurtenant structure must be adequately anchored to prevent flotation, collapse, and lateral movement;
iv. Any machinery or equipment servicing the appurtenant structure must be elevated or floodproofed to or above the BFE;
v. The appurtenant structure must comply with floodway encroachment provisions in subsection (C) of this section;
vi. The appurtenant structure must be designed to allow for the automatic entry and exit of flood waters in accordance with subsection (B)(1)(c) of this section;
vii. The structure must have low damage potential;
viii. If the structure is converted to another use, it must be brought into full compliance with the standards governing such use; and
ix. The structure must not be used for human habitation.
b. Detached garages, storage structures, and other appurtenant structures not meeting the above standards must be constructed in accordance with all applicable standards in subsection (B)(1) of this section.
c. Upon completion of the structure, certification that the requirements of this section have been satisfied shall be provided to the floodplain administrator for verification.
7. Additional Flood Fringe Standards. Structures that do not require a building permit and that do not have any associated fill are allowed, subject to flood hazard area review and permitting. Any other proposed development, encroachment, clearing and grading, new construction, or substantial improvements are prohibited in a flood fringe area, except as permitted under the following standards:
a. Vehicular, Pedestrian, and Nonmotorized Access. Roads, bridges, driveways, trails, emergency vehicle access, and access routes and easements, where allowed, shall be constructed and armored based on the standards in subsection (B)(7)(b) of this section and elevated a minimum of one foot above the base flood elevation. Parking lots shall be elevated to a minimum of one-half foot below the base flood elevation.
b. Clearing and Grading. Development under this subsection shall be designed to a zero-rise standard (see EMC 14.80.050(E) and subsection (C)(1) of this section). Any grading associated with the development shall not cause an adverse impact to adjacent, cross-channel, or upstream or downstream properties, nor increase flood hazards, water velocities, or flood elevations. In addition to meeting the requirements for zero-rise, all permitted development must also meet the following requirements:
i. Compensatory Storage. New excavated storage volume shall be equivalent to the flood storage capacity eliminated by grading within the flood fringe. “Equivalent” shall mean that the storage removed shall be replaced by equal live storage volume between corresponding one-foot contour intervals that are hydraulically connected to the floodplain through their entire depth.
ii. Flow Conveyance. New excavated conveyance areas shall be equivalent to existing conveyance within the flood fringe. “Equivalent” shall mean a mechanism for transporting water from one point to another using an open channel system.
iii. Erosion Protection. Development shall be protected from flow velocities greater than two feet per second through the use of bioengineering methods or, when bioengineering methods have been deemed insufficient to protect development, then hard armoring may be utilized. All erosion protection shall extend one to three feet, depending on development requirements, above the base flood elevation and shall be covered with topsoil and planted with native vegetation.
c. AE and A1-30 Zones with Base Flood Elevations but No Floodways. In areas with BFEs (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 at any point within the community.
C. Floodways. Located within areas of special flood hazard established in EMC 14.80.020 and 14.80.040 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the depth and/or velocity of floodwaters that can carry debris, and increased erosion potential, any development, encroachment, clearing and grading, fill, new construction, or substantial improvements, including structures that do not require a building permit, shall be prohibited within the floodway, except as allowed by the following provisions:
1. No Rise Standard. If any of the following allowed activities require installation of structures or any fill within the floodway, certification by a registered professional engineer must be 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 (see EMC 14.80.050(E)).
2. Residential Construction in Floodways. Construction or 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, 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 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 50 percent.
a. Replacement of Farmhouses in Floodway. Repairs, reconstruction, replacement, or improvements to existing farmhouse structures located in designated floodways and that are located on lands designated as agricultural lands of long-term commercial significance under RCW 36.70A.170 may be permitted subject to the following:
i. The new farmhouse is a replacement for an existing farmhouse on the same farm site;
ii. There is no potential building site for a replacement farmhouse on the same farm outside the designated floodway;
iii. Repairs, reconstruction, or improvements to a farmhouse shall not increase the total square footage of encroachment of the existing farmhouse;
iv. A replacement farmhouse shall not exceed the total square footage of encroachment of the farmhouse it is replacing;
v. A farmhouse being replaced shall be removed, in its entirety, including foundation, from the floodway within 90 days after occupancy of a new farmhouse;
vi. For substantial improvements and replacement farmhouses, the elevation of the lowest floor of the improvement and farmhouse respectively, including basement, is a minimum of two feet higher than the BFE;
vii. New and replacement water supply systems are designed to eliminate or minimize infiltration of flood waters into the system;
viii. New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of flood water into the system and discharge from the system into the flood waters; and
ix. All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage.
b. Substantially Damaged Residences in Floodway.
i. For all substantially damaged residential structures, other than farmhouses, located in a designated floodway, the floodplain administrator may make a written request that the Washington 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).
ii. 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:
(A) There is no potential safe building location for the replacement residential structure on the same property outside the regulatory floodway.
(B) A replacement residential structure is a residential structure built as a substitute for a legally existing residential structure of equivalent use and size.
(C) Repairs, reconstruction, or replacement of a residential structure shall not increase the total square footage of floodway encroachment.
(D) The elevation of the lowest floor of the substantially damaged or replacement residential structure is a minimum of two feet higher than the BFE.
(E) New and replacement water supply systems are designed to eliminate or minimize infiltration of flood water into the system.
(F) New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of flood water into the system and discharge from the system into the flood waters.
(G) All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage.
3. All Other Building Standards Apply in the Floodway. If subsection (C)(1) of this section is satisfied or construction is allowed pursuant to subsection (C)(2) of this section, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section, Provisions for flood hazard reduction.
4. Other Allowable Activities in the Floodway.
a. Agricultural activities that do not require the installation of structures and that do not have any associated fill.
b. Park and recreational uses and facilities that do not require the installation of structures and that do not have any associated fill.
c. Habitat enhancement or stream restoration activities, subject to the provisions outlined in EMC 14.50.060.
d. Private bridges may be allowed to cross the floodway; provided, that the structure meets the requirements contained in EMC 14.80.050 and the following:
i. The lowest structural member of a private bridge proposed to cross a channel migration zone shall be a minimum of six feet above the base flood elevation.
ii. The lowest structural member of a private bridge proposed to cross the floodway portion of any other watercourse shall be a minimum of one foot above the base flood elevation.
D. General Requirements for Other Development. All development, including manmade changes to improved or unimproved real estate for which specific provisions are not specified in this chapter or the state building codes with adopted amendments and any Edgewood amendments, shall:
1. Be located and constructed to minimize flood damage;
2. Meet the encroachment limitations of this chapter if located in a regulatory floodway;
3. Be anchored to prevent flotation, collapse, or lateral movement resulting from hydrostatic loads, including the effects of buoyancy, during conditions of the design flood;
4. Be constructed of flood damage-resistant materials;
5. Meet the flood opening requirements of EMC 14.80.060(B)(1)(c); and
6. Have mechanical, plumbing, and electrical systems above the design flood elevation or meet the requirements of ASCE 24, except that minimum electric service required to address life safety and electric code requirements is permitted below the design flood elevation, provided it conforms to the provisions of the electrical part of building code for wet locations.
E. Critical Facilities. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the SFHA (100-year floodplain). Construction of new critical facilities shall be permissible within the SFHA if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor elevated three feet above BFE or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility should also be protected to the height utilized above. 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 facility’s lowest floor shall be provided to all critical facilities to the extent possible.
F. Livestock Sanctuaries. 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 (at least one foot above the BFE). Proposals for livestock flood sanctuaries shall meet all procedural and substantive requirements of this chapter. (Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).
14.80.070 Variances to flood hazard areas.
The variance criteria set forth in this section are based on the general principle of zoning law that variances pertain to a piece of property and are not personal in nature. A variance may be granted for a parcel of property with physical characteristics so unusual that complying with the requirements of this chapter would create an exceptional hardship to the applicant or the surrounding property owners. The characteristics must be unique to the property and not be shared by adjacent parcels. The unique characteristic must pertain to the land itself, not to the structure, its inhabitants, or the owner(s) of the property.
It is the duty of the city of Edgewood to help protect its citizens from flooding. This need is so compelling and the implications of the cost of insuring a structure built below the base flood elevation are so serious that variances from the flood elevation or from other requirements in the flood ordinance should be quite rare. The long-term goal of preventing and reducing flood loss and damage can only be met if variances are strictly limited. Therefore, the variance guidelines provided in this chapter are more detailed and contain multiple provisions that must be met before a variance can be properly granted. The criteria are designed to screen out those situations in which alternatives other than a variance are more appropriate.
A. General. Variances are reviewed pursuant to the process and criteria outlined in EMC 14.10.100, Variances to critical areas.
B. Requirements for Flood Hazard Area Variances. In addition to the variance criteria referenced in subsection (A) of this section, 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 local laws or ordinances;
2. For the repair, rehabilitation, or restoration of historic structure(s), upon a determination that the variance will not preclude the structure’s continued designation as a historic structure and that the variance is the minimum necessary to preserve the historic character and design of the structure (if applicable);
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; and
5. Upon a determination that failure to grant the variance would result in exceptional hardship to the applicant and that the hardship was not created by the applicant.
C. Variances shall not be issued within a designated floodway if any increase in flood levels during the base flood discharge would result.
D. Generally, variances may be issued for new construction and substantial improvements to be erected on a lot of one-half acre or less in size contiguous to and surrounded by lots with existing structures constructed below the BFE, provided the procedures of EMC 14.80.014, 14.80.015, and 14.80.060 have been fully considered. As the lot size increases beyond one-half acre, the technical justification required for issuing the variance increases.
E. Variance Criteria. In considering variance applications, the Edgewood hearing examiner shall consider all technical evaluations, all relevant factors, all standards specified in other sections of this chapter, and:
1. The danger that materials may be swept onto other lands to the injury of others;
2. The danger to life and property due to flooding or erosion damage;
3. The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner;
4. The importance of the services provided by the proposed facility to the community;
5. The necessity to the facility of a waterfront location, if applicable;
6. The availability of alternative locations for the proposed use, which are not subject to flooding or erosion damage;
7. The compatibility of the proposed use with existing and anticipated development;
8. The relationship of the proposed use to the comprehensive plan and floodplain management program for that area;
9. The safety of access to the property in time of flood for ordinary and emergency vehicles;
10. The expected heights, velocity, duration, rate of rise, and sediment transport of the flood waters expected at the site; and
11. 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, water system, and streets and bridges.
F. Additional Requirements for the Issuance of a Variance.
1. Any applicant to whom a variance is granted shall be given written notice over the signature of a community official that:
a. 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 $25.00 for $100.00 of insurance coverage; and
b. Such construction below the BFE increases risks to life and property.
2. The floodplain administrator shall maintain a record of all variance actions, including justification for their issuance.
3. The floodplain administrator shall condition the variance as needed to ensure that the requirements and criteria of this chapter are met.
4. Variances as interpreted in the National Flood Insurance Program are based on the general zoning law principle that they pertain to a physical piece of property; they are not personal in nature and do not pertain to the structure, its inhabitants, economic or financial circumstances. They primarily address small lots in densely populated residential neighborhoods. As such, variances from flood elevations should be quite rare. (Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).
14.80.075 Penalties for noncompliance.
All development within special flood hazard areas is subject to the terms of this chapter and other applicable regulations. 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 civil violation under EMC Title 7. Any person who violates this chapter or fails to comply with any of its requirements shall upon conviction thereof be fined in accordance with EMC Title 7. Nothing herein contained shall prevent the city from taking such other lawful action as is necessary to prevent or remedy any violation. (Ord. 20-589 § 1 (Exh. A)).
14.80.080 Appendices.
A. Floodplain/Floodway Analysis.
APPENDIX A
FLOODPLAIN/FLOODWAY ANALYSIS
This appendix describes the flood hazard analyses and studies as required by this chapter. Flood hazard studies establish the base flood elevation and delineate floodplain and/or floodway(s) when a proposed project contains or is adjacent to a river, stream, lake, or closed depression.
Flood hazard studies must conform to FEMA regulations described in 44 CFR Part 65. In addition, the following information must be provided and procedures performed for flood hazard studies used under this chapter to examine development proposals or improvements within a floodplain.
Article I. Flood Study Content and Required Information
When required under EMC 14.80.050(C), the completed floodplain/floodway analysis study report and the modeling digital files shall be submitted with the development permit (EMC 14.80.045). The report submittal must be stamped by a licensed professional civil engineer and include the following information in addition to that required for the drainage plan of a proposed project:
A. Floodplain/Floodway Map.
1. A scaled survey base map stamped by a licensed professional land surveyor registered in the state of Washington. The map must accurately locate the proposed development with respect to the floodplain and floodway, the channel of the subject stream, river, and/or closed depression location, and the existing improvements within the subject study area. It must also supply all pertinent information such as the nature of the proposed project, legal description of the property on which the project would be located, fill quantity, limits and elevation, the building floor elevations, and use of compensatory storage.
2. The map must show elevation contours at a minimum of two-foot vertical intervals and shall comply with survey and map guidelines published in the FEMA publication Guidelines and Specifications for Study Contractors. The map must show the following:
a. Elevations and ground contours, spot elevations, and vertical datum NAVD 88 (North American Vertical Datum of 1988) (or most recent vertical datum accepted by the department).
b. Elevations and dimensions of existing structures, fill, and compensatory storage areas.
c. Size, location, elevation and spatial arrangement of all proposed structures on the site.
d. Location and elevations of roadways, drainage facilities, water supply lines, and sanitary sewer facilities.
e. Areas of DFF must clearly be shown and plotted on the map sheet depicting the bounded area of the floodway on both sides of the study channel through the subject site. DFF floodway studies must reflect all transitions as referenced above as well.
f. The base maps must also be accompanied by all field survey notes/computations, drawings, etc., for each cross-section with water surface elevation at the time the cross-section field survey was done.
B. Study Report.
1. Soil maps, groundcover maps, and photographs.
2. A narrative report containing the purpose of the study and description of the study area, data collection, methodology for both the hydrology and hydraulics, detailed discussion on the input parameters used, modeling results, and conclusions.
3. A floodplain/floodway analysis must include calculations and all computer analysis input and output information, supporting graphical illustrations, as well as the following additional information:
a. Scaled cross-sections showing the current, existing conditions of the river or stream channel, the floodplain adjoining each side of the channel, the computed floodway, the cross-sectional area to be occupied by any proposed development and all historic high water information.
b. Profiles showing the bottom of the channel, the top of both left and right banks and computed base floodwater surface elevations for the 10-year, 25-year, 50-year and 100-year events.
c. Plans and specifications of any flood protection for structures, construction areas, clearing, dredging, channel improvements, storage of materials, water supply, and sanitary facilities within the floodplain.
d. Complete digital printout of input and output data of the model that was used for the analysis. Liberal use of comments and written discussion will assist considerably in understanding the model logic and minimize misinterpretations and/or questions.
e. A map, showing the graphical/plotted location and limits of the computed floodway and/or floodplain.
f. Ready-to-run digital files of both the hydrologic and hydraulic model and its input and output files used in the study.
g. A section on the flood flow including computer modeling or calculations.
h. Aerial photographs of the site.
i. All field survey notes/computations, maps, and drawings for each cross-section with water surface elevation at the time of the cross-section field survey.
C. Computer Modeling Information. Floodway/floodplain studies submitted to the city for review must include output summary tables and include the following (but not limited to) items:
1. Cross-section(s) identification number.
2. Range of flows being examined.
3. Computed water surface elevation at each cross-section.
4. Energy grade line at each cross-section.
5. Graphical plots of the channel cross-sections with computed water surface elevations for all model runs including calibrated model runs.
6. All model input and output reports.
7. Graphical plots of the model output data that show the points and segments along each cross-section where deep and/or fast-flowing water occurs. This shall include cross-section plots of depth and velocity in one-unit increments. The plots shall also be accompanied with a table listing the station distance (right and left bank), flow rate, area, hydraulic depth, velocity, and whether each point is a floodway.
8. A plan sheet clearly showing the graphical representation of the bounded area of the floodway based on DFF criteria through the entire study site and reach. Note that identified islands or pockets within the middle of the bounded floodway area are generally considered as part of the floodway, unless otherwise approved by the department.
9. Discussion on the starting water surface elevation for the hydraulic model.
Article II. Determining Flood Flows
The two techniques used to determine the flows used in a flood study depend on whether a basin plan has been adopted or a detailed flood study has been done and approved for use by the department. The first technique is for basins with adopted basin plan areas. The second technique is used on ungauged catchments or those with an insufficient length of record. In either case, the engineer shall be responsible for assuring that the hydrologic methods used are technically reasonable, conservative, conform to the FEMA publication Guidelines and Specifications for Study Contractors, and are acceptable by FEMA and the department.
A. Flood Flows from Adopted Basin Plan Information. Flood flows may be determined using information from the city’s basin plan. The hydrologic model used in the basin plan shall be updated to include the latest changes in zoning or any additional information regarding the basin which has been acquired since the adoption of the basin plan.
B. Flood Flows from a Calibrated Continuous Model. Flood flows may be determined by utilizing a continuous flow simulation model such as HSPF or other equivalent continuous flow simulation model, as approved by the city. Where flood elevation or stream gauging data are available, the model shall be calibrated to the known data. Otherwise, regional parameters may be used.
Article III. Determining Flood Elevations, Profiles and Floodways (Hydraulic Model)
A. Reconnaissance. The applicant’s project engineer is responsible for the collection of all existing data with regard to flooding in the study area. This shall include a literature search of all published reports in the study area and adjacent communities and an information search to obtain all unpublished information on flooding in the immediate and adjacent areas from federal, state, and local units of government. This search shall include specific information on past flooding in the area, drainage structures such as bridges and culverts that affect flooding in the area, available topographic maps, available community maps, photographs of past flood events, and general flooding problems within the community. Documented discussions with nearby property owners should also be done to obtain a witness account of the flooding extent. A field reconnaissance shall be made by the applicant’s project engineer to determine hydraulic conditions of the study area, including type and number of structures, locations of cross-sections, and other parameters including the roughness values necessary for the hydraulic analysis.
B. Base Data. Channel cross-sections used in the hydraulic analysis shall be current/existing at the time the study is performed and shall be obtained by field survey. Topographic information obtained from aerial photographs/mapping may be used in combination with surveyed channel cross-sections in the hydraulic analysis. The elevation datum of all information used in the hydraulic analysis shall be verified. All information shall be referenced directly to NAVD 1988 (and include local correlation to NGVD) unless otherwise approved by the city.
C. Methodology. Flood studies and analysis (including deep and/or fast-flowing floodways and zero-rise analysis) shall be calculated using the U.S. Army Corps of Engineers HEC-RAS computer model (or subsequent revision) unless otherwise approved by the city.
D. Adequacy of the Hydraulic Model. Edgewood considers the following (but not limited to) factors when determining the adequacy of the hydraulic model for use in the floodway/floodplain model:
1. Cross-section of a downstream starting location and spacing.
2. Differences in energy grade line (significant differences in the energy grade line from cross-section to cross-section are an indication that cross-sections should be more closely spaced or that other inaccuracies exist in the hydraulic model).
3. Methods and results for analyzing the hydraulics of structures such as bridges and culverts.
4. Lack of flow continuity.
5. Use of a gradually varied flow model. In certain cases, rapidly varied flow techniques may need to be used in combination with a gradually varied flow model such as weir flow over a levee, flow through a spillway of a dam, or special application of bridge flow (pressure flow if bridge superstructure is shown to be submerged for the study event).
6. Manning’s “n” value.
7. Calibration of hydraulic model to known or observed flow stage elevations including past flood events.
8. Special Applications. In some cases, steady state one-dimensional hydraulic models may not be sufficient for preparing the floodplain/floodway analysis. This may occur where sediment transport, two-dimensional flow, or other unique hydraulic circumstances affect the accuracy of the model. In these cases, the project engineer must propose and obtain department approval of alternative models for establishing the water surface elevations.
9. All reported error or warning messages by the model must be properly and adequately addressed or resolved and included in the report for review verification.
Article IV. Zero-Rise Analysis (ZRA)
A. Zero-rise analysis (ZRA) is required where encroachment within the flood fringe and/or floodway area is allowed and approved by the department. The ZRA must show that the proposed development encroachment in the flood fringe area will not create any rise in the base flood elevation resulting from a comparison of existing conditions and proposed conditions. This is directly attributable to development in the floodplain but not attributable to manipulation of mathematical variables such as roughness factors, coefficients, discharge, and other hydraulic parameters.
B. ZRA is also required where development is proposed within a closed depression basin, having surface water runoff that is tributary to said closed depression, but no encroachment of the flood fringe or floodway is proposed. In this case, the ZRA must show that the proposed development will not create more than a 0.01-foot rise in the base flood elevation resulting from a comparison of existing conditions and proposed conditions. This is directly attributable to the change in land cover by the proposed development, but not attributable to manipulation of mathematical variables such as roughness factors, coefficients, discharge, and other hydraulic parameters.
C. In addition to those items listed in subsection (A) of this article, the following shall be included in a ZRA on projects that encroach within the flood fringe and/or floodway area:
1. Floodway boundaries (based on zero-rise) are to follow the stream lines and reasonably balance the rights of property owners on either side of the floodway. Use of the automatic equal conveyance encroachment option in the model will be considered equitable.
2. The ZRA must include a sufficient number of cross-sections in order to accurately model the subject fill and compensatory storage areas of the site. In all cases, cross-sections shall be located downstream, through the subject site and upstream of the site at a very minimum. They shall also be located where changes in channel and the fill material characteristics occur, such as slope, shape, and roughness. The sections shall also be located perpendicular to the flow path in the channel and the outside overbank areas. The department shall review and approve the proposed number and location of cross-sections. All cross-sections and surveys shall be prepared and certified by a professional land surveyor or registered professional engineer in the state of Washington.
3. The difference between two profiles of water surface elevation at the cross-section, e.g., difference between existing and encroached water surface. The model must report 0.01 feet or less an allowable change in the water surface elevation. This must be shown in the profile graphical plot as well.
4. The difference between profiles of the energy grade line at the cross-section. The model must report 0.01 feet or less. This is the allowable change in the energy grade line. This must be shown in the profile graphical plot as well.
D. Conveyance Capacity.
1. The ZRA must also show that the proposed development encroachment in the flood fringe area will not show a measurable decrease (less than 0.01 CFS) in the conveyance capacity of the channel, resulting from a comparison of existing conditions and proposed conditions, for each of the cross-sections. This is also directly attributable to development in the floodplain but not attributable to manipulation of mathematical variables such as roughness factors, coefficients, discharge, and other hydraulic parameters.
2. The analysis must provide calculations of the reduction in conveyance caused by the proposed development encroachment, assuming no change in the water surface elevation, and using the roughness coefficient value(s) appropriate for the proposed development.
3. The analysis must then provide calculations for the increase in conveyance of the proposed compensatory measure, using the roughness coefficient value(s) appropriate for the proposed development.
4. Include a comparison analysis and discussion from subsections (C)(2) and (3) of this article. The comparison must adequately show that the conveyance capacity has not measurably decreased between the existing condition and proposed development condition.
Floodplain/Floodway Zero-Rise Certification
This is to certify that I am a duly qualified professional Engineer licensed to practice in the state of Washington.
This is to further certify that the attached Floodplain/Floodway zero-rise analysis conclusively shows that the proposed development of: ________________________________
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will not increase the 100-year Base Flood elevation(s) and widths nor reduce the conveyance capacity of the Floodplain, Floodway and its associated channel to the
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(Name of River, Stream, Closed Depression or other Watercourse)
Supporting Data
Base Flood Elevation (Pre-Development) = __________________ FT (NAVD 88)
Base Flood Elevation (Post-Development) = __________________ FT (NAVD 88)
Conveyance Capacity (Pre-Development) = __________________ CFS
Conveyance Capacity (Post-Development) = __________________ CFS
with compensatory storage)
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(Ord. 20-589 § 1 (Exh. A); Ord. 17-513 § 3 (Exh. A)).