Chapter 2.10 –
Special Flood Hazard Area Overlay District1
Sections:
2.10.100 Statutory Authorization, Findings of Fact, Statement of Purpose and Methods
2.10.200 Methods of Reducing Flood Losses
2.10.800 Information to Be Obtained and Maintained
2.10.900 Requirement to Notify Other Entities and Submit New Technical Data
2.10.1000 Substantial Improvement and Substantial Damage Assessments and Determinations
2.10.1100 Establishment of Development Permit
2.10.1200 Development Standards
2.10.1300 SFHA Variance Procedure
2.10.1400 Provisions for Flood Hazard Reduction
2.10.1500 Subdivision Proposals and Other Proposed Developments
2.10.1600 Use of Other Base Flood Data
2.10.1700 Structures Located in Multiple or Partial Flood Zones
2.10.1900 Specific Standards for Riverine (Including All Non-Coastal) Flood Zones
2.10.100 Statutory Authorization, Findings of Fact, Statement of Purpose and Methods
A. Statutory Authorization. The State of Oregon has in ORS 197.175 delegated the responsibility to local governmental units to adopt floodplain management regulations designed to promote the public health, safety, and general welfare of its citizenry. Therefore, the City of Sisters does ordain as follows:
B. Findings of Fact.
1. The flood hazard areas of the City of Sisters are subject to periodic inundation which may result in loss of life and property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood protection and relief, and impairment of the tax base, all of which adversely affect the public health, safety, and general welfare.
2. These flood losses may be caused by the cumulative effect of obstructions in special flood hazard areas which increase flood heights and velocities, and, when inadequately anchored, cause damage in other areas. Uses that are inadequately floodproofed, elevated, or otherwise protected from flood damage also contribute to flood loss.
C. An overlay zone is a special zoning district which is applied over one or more base zoning districts and establishes additional or stricter standards and criteria for covered properties in addition to those of the underlying zoning district. This Special Flood Hazard Area (SFHA) overlay district zone intends to identify sections of the City subject to the hazards of 100-year periodic stream flooding as determined by the limits and extent of the Special Flood Hazard Area shown on Federal Emergency Management Agency (FEMA) Flood Insurance Map (FIRM) No. 41017C0245D, dated September 28, 2007, and associated Flood Insurance Study No. 19163CV000A, and any revision thereto, or more accurate studies, and to preclude future development or redevelopment that may suffer a loss of life or property in the subject area. Because the natural watercourse of waterways is dynamic and subject to change, the boundaries of the Special Flood Hazard Area Overlay District may be revisited and adjusted, as necessary and warranted.
D. It is the purpose of this Chapter to promote the public health, safety and general welfare, to maintain streams and floodplains in their natural state to the maximum extent practical to reduce flood hazards, and to minimize public and private losses due to flooding in flood hazard areas by provisions designed to:
1. Protect human life and health;
2. Minimize expenditure of public money for costly flood control projects;
3. Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;
4. Minimize prolonged business interruptions;
5. Minimize damage to public facilities and utilities such as water and gas mains; electric, telephone and sewer lines; streets and bridges located in areas of special flood hazards;
6. Help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard so as to minimize blight areas caused by flooding;
7. Notify potential buyers that the property is in an area of special flood hazard;
8. Notify those who occupy special flood hazard areas that they assume responsibility for their actions;
9. Participate in and maintain eligibility for flood insurance and disaster relief;
10. Minimize the threat to persons, property and urban water quality from flooding and inadequate or improper drainage resulting from uncontrolled development or redevelopment of land to include filling, grading, excavation, removal; earthwork construction including berms and dikes; stockpiling of materials; or other alterations;
11. Ensure that flood loss reduction measures under the National Flood Insurance Program (NFIP) are consistent with retaining natural floodplain functions;
12. Ensure no net loss of hydraulic and geomorphic functions of floodplains;
13. To balance the public interests with those of individual property owners in the designated areas;
14. Allow the functions of the creek to continue, including erosion, deposition, and channel migration;
15. To implement the policies of the City’s Comprehensive Plan. [Ord. 505 § 2 (Exh. B), 2020].
2.10.200 Methods of Reducing Flood Losses
In order to accomplish its purposes, this Chapter includes methods and provisions for:
A. Restricting or prohibiting development which 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, including facilities which serve such uses, 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 floodwaters;
D. Controlling filling, grading, dredging, and other development which may increase flood damage;
E. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or may increase flood hazards in other areas. [Ord. 505 § 2 (Exh. B), 2020].
2.10.300 Definitions
The following definitions apply to this Chapter and, to the extent the term is not defined in Chapter 1.3, to other portions of the Development Code. Strictly for purposes of this Chapter, the definitions supersede conflicting definitions in Chapter 1.3. Unless specifically defined below, words or phrases used in this ordinance shall be interpreted so as to give them the meaning they have in common usage.
Appeal: A request for a review of the interpretation of any provision of this chapter or a request for a variance.
Area of shallow flooding: 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.
Area of special flood hazard: The land in the floodplain within a community subject to a 1 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, AR. “Special flood hazard area” is synonymous in meaning and definition with the phrase “area of special flood hazard.”
Base flood: The flood having a one percent chance of being equaled or exceeded in any given year.
Base flood elevation (BFE): The elevation to which floodwater is anticipated to rise during the base flood.
Basement: Any area of the building having its floor subgrade (below ground level) on all sides.
Below-grade crawl space: Means an enclosed area below the base flood elevation in which the interior grade is not more than two feet below the lowest adjacent exterior grade and the height, measured from the interior grade of the crawl space to the top of the crawl space foundation, does not exceed 4 feet at any point.
Building: See “Structure.”
Critical facility: Means a facility for which even a slight chance of flooding might be too great. Critical facilities include, but are not limited to, schools, nursing homes, hospitals, police, fire and emergency response installations, installations which produce, use, or store hazardous materials or hazardous waste.
Development: Any manmade change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations or storage of equipment or materials.
Elevated building: Means, for insurance purposes, a nonbasement building which has its lowest elevated floor raised above ground level by foundation walls, shear walls, post, piers, pilings, or columns.
Flood or flooding:
1. A general and temporary condition of partial or complete inundation of normally dry land areas from:
a. The overflow of inland or tidal waters.
b. The unusual and rapid accumulation or runoff of surface waters from any source.
c. Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in subsection (1)(b) 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.
2. 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 (1)(a) of this definition.
Flood elevation study: 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.
Flood Insurance Rate Map (FIRM): The official map of a community, on which the Federal Insurance Administrator has delineated both the special hazard areas and the risk premium zones applicable to the community. A FIRM that has been made available digitally is called a Digital Flood Insurance Rate Map (DFIRM).
Flood Insurance Study (FIS): See “Flood elevation study.”
Flood proofing: 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.
Floodplain or flood prone area: Any land area susceptible to being inundated by water from any source. See “Flood or flooding.”
Floodplain administrator: The community official designated by title to administer and enforce the floodplain management regulations.
Floodplain management: The operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to emergency preparedness plans, flood control works, and floodplain management regulations.
Floodplain management regulations: Zoning Chapters, subdivision regulations, building codes, health regulations, special purpose Chapters (such as floodplain Chapter, grading Chapter and erosion control Chapter) and other application of police power. The term describes such state or local regulations, in any combination thereof, which provide standards for the purpose of flood damage prevention and reduction.
Floodway: The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height. Also referred to as “Regulatory Floodway.”
Functionally dependent use: A use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, and does not include long term storage or related manufacturing facilities.
Hazardous material: The Oregon Department of Environmental Quality defines hazardous materials to include any of the following:
1. Hazardous waste as defined in ORS 466.005;
2. Radioactive waste as defined in ORS 469.300, radioactive material identified by the Energy Facility Siting Council under ORS 469.605 and radioactive substances defined in ORS 453.005;
3. Communicable disease agents as regulated by the Health Division under ORS Chapter 431 and 433.010 to 433.045 and 433.106 to 433.990;
4. Hazardous substances designated by the United States Environmental Protection Agency (EPA) under section 311 of the Federal Water Pollution Control Act, P.L. 92-500, as amended;
5. Substances listed by the United States EPA in section 40 of the Code of Federal Regulations, Part 302 – Table 302.4 (list of Hazardous Substances and Reportable Quantities) and amendments;
6. Material regulated as a Chemical Agent under ORS 465.550;
7. Material used as a weapon of mass destruction, or biological weapon;
8. Pesticide residue;
9. Dry cleaning solvent as defined by ORS 465.200(9).
Highest adjacent grade: The highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.
Historic structure: Any structure that is:
1. Listed individually in the National Register of Historic Places (a listing maintained by the Department of Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;
2. 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;
3. Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of Interior; or
4. Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:
a. By an approved state program as determined by the Secretary of the Interior; or
b. Directly by the Secretary of the Interior in states without approved programs.
Letter of Map Change (LOMC): Means an official FEMA determination, by letter, to amend or revise effective Flood Insurance Rate Maps and Flood Insurance Studies. The following are categories of LOMCs:
1. Conditional Letter of Map Amendment (CLOMA): A CLOMA is FEMA’s comment on a proposed structure or group of structures that would, upon construction, be located on existing natural ground above the base (1 percent annual chance) flood elevation on a portion of a legally defined parcel of land that is partially inundated by the base flood.
2. Conditional Letter of Map Revision (CLOMR): A CLOMR is FEMA’s comment on a proposed project that would, upon construction, affect the hydrologic or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway, the effective base flood elevations, or the special flood hazard area.
3. Conditional Letter of Map Revision based on Fill (CLOMR-F): A CLOMR-F is FEMA’s comment on a proposed project that would, upon construction, result in a modification of the special flood hazard area through the placement of fill outside the existing regulatory floodway.
4. Letter of Map Amendment (LOMA): An official amendment, by letter, to the Flood Insurance Rate Maps (FIRMs) based on technical data showing that an existing structure, parcel of land or portion of a parcel of land that is naturally high ground, (i.e., has not been elevated by fill) above the base flood, that was inadvertently included in the special flood hazard area.
5. Letter of Map Revision (LOMR): A LOMR is FEMA’s modification to an effective Flood Insurance Rate Map (FIRM), or Flood Boundary and Floodway Map (FBFM), or both. LOMRs are generally based on the implementation of physical measures that affect the hydrologic or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway, the effective base flood elevations, or the SFHA. The LOMR officially revises the FIRM or FBFM, and sometimes the Flood Insurance Study (FIS) report, and, when appropriate, includes a description of the modifications. The LOMR is generally accompanied by an annotated copy of the affected portions of the FIRM, FBFM, or FIS report.
6. Letter of Map Revision based on Fill (LOMR-F): A LOMR-F is FEMA’s modification of the special flood hazard area shown on the Flood Insurance Rate Map (FIRM) based on the placement of fill outside the existing regulatory floodway.
7. PMR: A PMR is FEMA’s physical revision and republication of an effective Flood Insurance Rate Map (FIRM) or Flood Insurance Study (FIS) report. PMRs are generally based on physical measures that affect the hydrologic or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway, the effective base flood elevations, or the special flood hazard area.
Lowest floor: The lowest floor of the lowest enclosed area (including basement). An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a basement area is not considered a building’s lowest floor; provided, that such enclosure is not built so as to render the structure in violation of the applicable nonelevation design requirements of this Chapter.
Manufactured dwelling: 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 attached to the required utilities. The term “manufactured dwelling” does not include a “recreational vehicle” and is synonymous with “manufactured home.”
Manufactured dwelling park or subdivision: A parcel (or contiguous parcels) of land divided into two or more manufactured dwelling lots for rent or sale.
Mean sea level: For purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum (NGVD) of 1929 or other datum, to which Base Flood Elevations shown on a community’s Flood Insurance Rate Map are referenced.
New construction: For floodplain management purposes, “new construction” means structures for which the “start of construction” commenced on or after the effective date of a floodplain management regulation adopted by the City of Sisters and includes any subsequent improvements to such structures.
Recreational vehicle: A vehicle which is:
1. Built on a single chassis;
2. 400 square feet or less when measured at the largest horizontal projection;
3. Designed to be self-propelled or permanently towable by a light duty truck; and
4. Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.
Regulatory floodway: See “Floodway.”
Sheet flow area: See “Area of shallow flooding.”
Special flood hazard area: See “Area of special flood hazard” for this definition.
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 from the date of the permit. 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 dwelling 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.
Structure: For floodplain management purposes, a walled and roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a manufactured dwelling.
Substantial damage: Damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.
Substantial improvement: Any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure before the “start of construction” of the improvement. This term includes structures which have incurred “substantial damage,” regardless of the actual repair work performed. The term does not, however, include either:
1. Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions; or
2. Any alteration of a “historic structure”; provided, that the alteration will not preclude the structure’s continued designation as a “historic structure.”
Water dependent: Means a structure for commerce or industry which cannot exist in any other location and is dependent on the water by reason of intrinsic nature of its operations.
Water surface elevation: The height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929, or other datum, of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas.
Variance: A grant of relief by the City of Sisters from the terms of a floodplain management regulation.
Violation: The failure of a structure or other development to be fully compliant with the community’s floodplain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required in this chapter is presumed to be in violation until such time as that documentation is provided. [Ord. 505 § 2 (Exh. B), 2020].
2.10.400 General Provisions
A. Lands to Which This Chapter Applies. This Chapter shall apply to all special flood hazard areas within the jurisdiction of City of Sisters, which have been designated as part of the Special Flood Hazard Area overlay.
B. Basis for Establishing the Special Flood Hazard Areas. The special flood hazard areas identified by the Federal Insurance Administrator in a scientific and engineering report entitled “The Flood Insurance Study (FIS) for Deschutes County, Oregon and Incorporated Areas,” dated September 28, 2007, with accompanying Flood Insurance Rate Maps (FIRMs) Panels 41017CIND0A and 41017C0245E are hereby adopted by reference and declared to be a part of this Chapter. The FIS and FIRM panels are on file at the Community Development Department located at City Hall.
C. Coordination with State of Oregon Specialty Codes. Pursuant to the requirement established in ORS 455 that the City of Sisters administers and enforces the State of Oregon Specialty Codes, the City of Sisters does hereby acknowledge that the Oregon Specialty Codes contain certain provisions that apply to the design and construction of buildings and structures located in special flood hazard areas. Therefore, this Chapter is intended to be administered and enforced in conjunction with the Oregon Specialty Codes.
D. Compliance and Penalties for Noncompliance.
1. Compliance. All development within special flood hazard areas is subject to the terms of this chapter and required to comply with its provisions and all other applicable regulations.
2. Penalties for Noncompliance. No structure or land shall hereafter be constructed, located, extended, converted, or altered without full compliance with the terms of this chapter and other applicable regulations. Violations of the provisions of this chapter by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions) shall constitute a class c violation and shall be subject to a fine of up to $500 per violation. Each violation of a separate provision of this chapter shall constitute a separate violation, and each day that a violation of this chapter is committed or permitted to continue shall constitute a separate violation. Violations of this chapter constitute a nuisance. In addition to any other remedies, the violations may be abated in accordance with the provisions of SMC Chapter 8.15. Nothing contained herein shall prevent the City of Sisters from taking such other lawful action as is necessary to prevent or remedy any violation.
E. Abrogation and Severability.
1. Abrogation. This chapter is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this chapter and another chapter, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.
2. Severability. This chapter and the various parts thereof are hereby declared to be severable. If any section, clause, sentence, or phrase of the chapter is held to be invalid or unconstitutional by any court of competent jurisdiction, then said holding shall in no way affect the validity of the remaining portions of this chapter.
F. Interpretation. In the interpretation and application of this chapter, all provisions shall be:
1. Considered as minimum requirements;
2. Liberally construed in favor of the governing body; and
3. Deemed neither to limit nor repeal any other powers granted under state statutes.
G. Warning and Disclaimer of Liability.
1. Warning. 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.
2. Disclaimer of Liability. This chapter shall not create liability on the part of the City of Sisters, any officer or employee thereof, or the Federal Insurance Administrator for any flood damages that result from reliance on this chapter or any administrative decision lawfully made hereunder. [Ord. 505 § 2 (Exh. B), 2020].
2.10.500 Uses
A. Permitted Uses.
1. The land uses listed in Table 2.10.500.A are permitted in the Special Flood Hazard Area Overlay District and in areas of special flood hazard as designated in 2.10.200, subject to the provisions of this Chapter. Only land uses that are specifically listed in Table 2.10.500.A, and land uses that are approved as “similar” to those in Table 2.10.500.A, may be permitted. The land uses identified as “Conditional Uses” in Table 2.10.500.A require Conditional Use Permit approval prior to development or a change in use, in accordance with Chapter 4.4. Applications for development within the Special Flood Hazard Area Overlay District shall be on an appropriate form provided by the Sisters Community Development Department, accompanied by the appropriate fee.
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Permitted Uses: |
Conditional Uses*: |
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A. Permitted uses below are allowed assuming fill is not added to the area of special flood hazard, and flood heights are not increased as a result of the permitted use: 1. Open space, excluding farming activities that require ground breaking. 2. Portions of a residential use that do not contain structures, such as lawn, garden or play areas. 3. Existing camping facilities, providing that waste disposal sites are not within the area subject to the hazards of 100-year periodic stream flooding. 4. Repair or remodel of an existing structure within its existing footprint, including buildings damaged by fire or other casualties. 5. Removal of noxious weeds. 6. Replacement of nonnative vegetation with native vegetation. 7. Ongoing activities such as lawn and garden maintenance. 8. Removal of hazardous trees. 9. Normal maintenance of existing public utilities and facilities. |
1. Crossings by transportation facilities and utility lines. 2. Parks, trails and pervious multi use paths. 3. Water-dependent uses, such as fish enhancement projects. 4. Restoration or enhancement of the stream bank, and bank stabilization projects. 5. A new single-family dwelling elevated without placement of fill on existing lots with less than 2,000 sq. ft. of land outside the 100-year floodplain as determined by site specific engineering, surveying, and hydrologic studies. 6. Expansion of existing dwellings in the 100-year floodplain. 7. Land divisions. All new lots created in the Special Flood Hazard Area Overlay District must result in a minimum of 2,000 sq. ft. of land area outside of the area of special flood hazard to serve as a building envelope. |
* Uses listed as “Conditional Uses” in Table 2.10.500.A above require Minor Conditional Use Permit approval prior to development or a change in use, in accordance with Chapter 4.4.
2. Similar use determinations shall be made in conformance with the procedures in Chapter 4.8 – Code Interpretations.
B. Prohibited Uses. The following uses and activities are prohibited within the Special Flood Hazard Area Overlay District or special flood hazard area, except as allowed in Table 2.10.500.A:
1. New dwellings on existing lots within areas of special flood hazard where 2,000 sq. ft. or more of area outside the area of special flood hazard is available for building.
2. New construction, including accessory buildings, is prohibited.
3. Clear cutting, scraping with motorized equipment, removal of root systems, or removal of native vegetation on stream banks.
4. Any encroachment during construction.
5. New impervious surfaces.
6. Removal of native vegetation on stream banks excluding trimming of no more than approximately 25% of the vegetation.
7. New clearing, grading, filling, land-disturbing activity or other “development,” other than for the purpose of replacing nonnative vegetation with native vegetation, and for other restoration work that may be approved by the local administrator.
8. Septic tanks and drain fields, dumping of any materials, hazardous or sanitary waste landfills, and receiving areas for toxic or hazardous waste or other contaminants.
9. Subdivision and partitioning of land for residential purposes is prohibited if land is located entirely within the Special Flood Hazard Area Overlay District or area of special flood hazard. All new lots created in the Special Flood Hazard Area Overlay District or area of special flood hazard must result in a minimum of 2,000 sq. ft. of land area outside of the area of special flood hazard to serve as a building envelope.
10. Modification of the stream channel, except for where necessary for bank stabilization and/or fish habitat enhancement projects.
11. Developments that would result in a rise of flood heights in the FEMA regulatory floodplain. [Ord. 505 § 2 (Exh. B), 2020].
2.10.600 Administration
A. Designation of the Floodplain Administrator. The Community Development Director is hereby appointed 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.
B. Duties and Responsibilities of the Floodplain Administrator. Duties of the Floodplain Administrator include, but are not limited to, the duties described in Sections 2.10.700 to 2.10.1000. [Ord. 505 § 2 (Exh. B), 2020].
2.10.700 Permit Review
The Floodplain Administrator shall:
A. Review all development permits to determine that the permit requirements of this Chapter have been satisfied and that all other required local, state, and federal permits have been obtained and approved;
B. Review all development permits to determine if the proposed development is located in a floodway. If located in the floodway, assure that the floodway provisions of this Chapter in section 2.10.2100 are met;
C. Review all development permits to determine if the proposed development is located in an area where Base Flood Elevation (BFE) data is available either through the Flood Insurance Study (FIS) or from another authoritative source. If BFE data is not available then ensure compliance with the provisions of section 2.10.1600;
D. Provide to building officials the Base Flood Elevation (BFE) plus 1.0' applicable to any building requiring a development permit;
E. Review all development permit applications to determine if the proposed development qualifies as a substantial improvement as defined in section 2.10.300;
F. Review all development permits to determine if the proposed development activity is a watercourse alteration. If a watercourse alteration is proposed, ensure compliance with the provisions in section 2.10.1400.A; and
G. Review all development permits to determine if the proposed development activity includes the placement of fill or excavation. [Ord. 505 § 2 (Exh. B), 2020].
2.10.800 Information to Be Obtained and Maintained
The following information shall be obtained and maintained by the Floodplain Administrator and shall be made available for public inspection as needed:
A. Obtain, record, and maintain the actual elevation (in relation to mean sea level) of the lowest floor (including basements) and all attendant utilities of all new or substantially improved structures where Base Flood Elevation (BFE) data is provided through the Flood Insurance Study (FIS), Flood Insurance Rate Map (FIRM), or obtained in accordance with section 2.10.1600.
B. Obtain and record the elevation (in relation to mean sea level) of the natural grade of the building site for a structure prior to the start of construction and the placement of any fill and ensure that the requirements of sections 2.10.2100 and 2.10.700.A are adhered to.
C. Upon placement of the lowest floor of a structure (including basement) but prior to further vertical construction, obtain documentation, prepared and sealed by a professional licensed surveyor or engineer, certifying the elevation (in relation to mean sea level) of the lowest floor (including basement).
D. Where base flood elevation data are utilized, obtain as-built certification of the elevation (in relation to mean sea level) of the lowest floor (including basement) prepared and sealed by a professional licensed surveyor or engineer, prior to the final inspection.
E. Maintain all Elevation Certificates (EC) submitted to the City of Sisters.
F. Obtain, record, and maintain the elevation (in relation to mean sea level) to which the structure and all attendant utilities were floodproofed for all new or substantially improved floodproofed structures where allowed under this Chapter and where Base Flood Elevation (BFE) data is provided through the FIS, FIRM, or obtained in accordance with section 2.10.1600.
G. Maintain all floodproofing certificates required under this Chapter.
H. Record and maintain all SFHA variance actions, including justification for their issuance.
I. Obtain and maintain all hydrologic and hydraulic analyses performed as required under section 2.10.2100.
J. Record and maintain all Substantial Improvement and Substantial Damage calculations and determinations as required under section 2.10.1000.
K. Maintain for public inspection all records pertaining to the provisions of this Chapter. [Ord. 505 § 2 (Exh. B), 2020].
2.10.900 Requirement to Notify Other Entities and Submit New Technical Data
A. Community Boundary Alterations. The floodplain administrator shall notify the Federal Insurance Administrator in writing whenever the boundaries of the community have been modified by annexation or the community has otherwise assumed authority or no longer has authority to adopt and enforce floodplain management regulations for a particular area, to ensure that all flood hazard boundary maps (FHBM) and flood insurance rate maps (FIRM) accurately represent the community’s boundaries. Include within such notification a copy of a map of the community suitable for reproduction, clearly delineating the new corporate limits or new area for which the community has assumed or relinquished floodplain management regulatory authority.
B. Watercourse Alterations. Notify adjacent communities, the Department of Land Conservation and Development, and other appropriate state and federal agencies, prior to any alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administration. This notification shall be provided by the applicant to the Federal Insurance Administration as a Letter of Map Revision (LOMR) along with either:
1. A proposed maintenance plan to assure the flood carrying capacity within the altered or relocated portion of the watercourse is maintained; or
2. Certification by a registered professional engineer that the project has been designed to retain its flood carrying capacity without periodic maintenance.
The applicant shall be required to submit a Conditional Letter of Map Revision (CLOMR) when required under section 2.10.900.C. Ensure compliance with all applicable requirements in sections 2.10.900.C and 2.10.1400.A.
C. Requirement to Submit New Technical Data. A community’s base flood elevations may increase or decrease resulting from physical changes affecting flooding conditions. As soon as practicable, but not later than six months after the date such information becomes available, a community shall notify the Federal Insurance Administrator of the changes by submitting technical or scientific data in accordance with Section 44 of the Code of Federal Regulations (CFR), Sub-Section 65.3. The community may require the applicant to submit such data and review fees required for compliance with this section through the applicable FEMA Letter of Map Change (LOMC) process.
The Floodplain Administrator shall require a Conditional Letter of Map Revision prior to the issuance of a floodplain development permit for:
1. Proposed floodway encroachments that increase the base flood elevation; and
2. Proposed development which increases the base flood elevation by more than one foot in areas where FEMA has provided base flood elevations but no floodway.
An applicant shall notify FEMA within six (6) months of project completion when an applicant has obtained a Conditional Letter of Map Revision (CLOMR) from FEMA. This notification to FEMA shall be provided as a Letter of Map Revision (LOMR).
The applicant shall be responsible for preparing all technical data to support CLOMR/LOMR applications and paying any processing or application fees associated with the CLOMR/LOMR.
The Floodplain Administrator shall be under no obligation to sign the Community Acknowledgement Form, which is part of the CLOMR/LOMR application, until the applicant demonstrates that the project will or has met the requirements of this code and all applicable state and federal laws. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1000 Substantial Improvement and Substantial Damage Assessments and Determinations
A. The Floodplain Administrator shall conduct Substantial Improvement (SI) (as defined in section 2.10.300) reviews for all structural development proposal applications and maintain a record of SI calculations within permit files in accordance with section 2.10.800. Conduct Substantial Damage (SD) assessments when structures are damaged due to a natural hazard event or other causes. Make SD determinations whenever structures within the special flood hazard area (as established in section 2.10.400.B) are damaged to the extent that the cost of restoring the structure to its before damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.
B. The Floodplain Administrator shall make interpretations where needed, as to exact location of the boundaries of the special flood hazard areas (for example, where there appears to be a conflict between a mapped boundary and actual field conditions). The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation. Such appeals shall be granted consistent with the standards of section 60.6 of the Rules and Regulations of the National Flood Insurance Program (44 CFR 59-76). [Ord. 505 § 2 (Exh. B), 2020].
2.10.1100 Establishment of Development Permit
A. Floodplain Development Permit Required. A development permit shall be obtained before construction or development begins within any area horizontally within the special flood hazard area established in section 2.10.400.B. The development permit shall be required for all structures, including manufactured dwellings, and for all other development, as defined in section 2.10.300, including fill and other development activities.
Development proposals within the Special Flood Hazard Area Overlay District shall be reviewed under a Type II procedure. Development approval within the Special Flood Hazard Area Overlay District shall be obtained before construction or development begins within any area of special flood hazard as established by this chapter. Approval shall be required for all structures, stream bank erosion control or enhancement projects, and development.
B. Application for Development Permit.
1. Application for a development within the SFHA shall be filed on forms furnished by the Floodplain Administrator. In addition to any other required materials for the applicable application, the submittal must include plans 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. The following information is also required:
a. In riverine flood zones, the proposed elevation (in relation to mean sea level), of the lowest floor (including basement) and all attendant utilities of all new and substantially improved structures; in accordance with the requirements of section 2.10.800.
b. Proposed elevation in relation to mean sea level to which any nonresidential structure will be floodproofed.
c. Certification by a registered professional engineer or architect licensed in the State of Oregon that the floodproofing methods proposed for any nonresidential structure meet the floodproofing criteria for nonresidential structures in section 2.10.2000.C.
d. Description of the extent to which any watercourse will be altered or relocated.
e. Base Flood Elevation data for subdivision proposals or other development when required per sections 2.10.700 and 2.10.1500.
f. Substantial improvement calculation for any improvement, addition, reconstruction, renovation, or rehabilitation of an existing structure.
g. The amount and location of any fill or excavation activities proposed. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1200 Development Standards
The following standards apply to all development and land divisions within the Special Flood Hazard Area Overlay District or area of special flood hazard in the City and its urbanizable areas:
A. In all areas of special flood hazard within the City and its urbanizable area as determined in Section 2.10.100, where base flood elevation data has been provided, the following provisions apply to all new and reconstructed structures:
1. Setbacks.
a. The purpose of setback requirements is to not encroach upon Whychus Creek and to protect structures from erosion and flooding while also allowing an economic use of the land.
b. The setback standards herein are to be used in combination with setback standards of the underlying district, with the more restrictive setbacks superseding the less restrictive setbacks.
c. All portions of new structures shall be sited within a distance of 1/2 the depth of the lot, away from the area of special flood hazard, measuring from the lot line opposite of the area of special flood hazard. The depth of the lot shall be determined by averaging the side lot lines. For example, if a lot is 150 ft. deep, all new structures shall be within 75 ft. of the lot line opposite to Whychus Creek. Setback standards of the underlying district apply in addition to this general setback standard.
d. Existing dwellings may be expanded, but not towards Whychus Creek. Existing setbacks from dwellings to Whychus Creek shall not be decreased as a result of expansions.
e. These setback requirements seek to decrease risks to structures from erosion and flooding. Where the literal application of the setback standards conflict with the purposes of this Chapter, a Major Variance may be used to allow placement of new structures to achieve this Chapter’s purposes.
B. Subdivision and partition proposals, for properties not entirely within the Special Flood Hazard Area Overlay District or area of special flood hazard shall have:
1. All new lots created result in a minimum of 2,000 sq. ft. of land area outside of the special flood hazard area to serve as building envelopes.
2. Measures to minimize flood damage.
3. Public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.
4. Adequate drainage provided to reduce exposure to flood damage.
5. Measures to prevent erosion and, where applicable, stream bank enhancement methods are incorporated into the subdivision design. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1300 SFHA Variance Procedure
The issuance of a SFHA variance is for floodplain management purposes only. Flood insurance premium rates are determined by federal statute according to actuarial risk and will not be modified by the granting of a SFHA variance.
A. Conditions for SFHA Variances.
1. Generally, SFHA 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 base flood level, in conformance with the provisions of subsections (A)(3) and (6) of this section. As the lot size increases beyond one-half acre, the technical justification required for issuing a SFHA variance increases.
2. SFHA variances shall only be issued upon a determination that the SFHA variance is the minimum necessary, considering the flood hazard, to afford relief.
3. SFHA variances shall not be issued within any floodway if any increase in flood levels during the base flood discharge would result.
4. SFHA variances shall only be issued upon:
a. A showing of good and sufficient cause;
b. A determination that failure to grant the SFHA variance would result in exceptional hardship to the applicant;
c. A determination that the granting of a SFHA 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 Chapters.
5. SFHA variances may be issued for the repair or rehabilitation of historic structures upon a determination that the proposed repair or rehabilitation of historic structures will not preclude the structure’s continued designation as a historic structure and the SFHA variance is the minimum necessary to preserve the historic character and design of the structure.
6. SFHA variances may be issued by a community for new construction and substantial improvements and for other development necessary for the conduct of a functionally dependent use; provided, that the criteria of subsections (A)(2) through (5) of this section are met, and the structure or other development is protected by methods that minimize flood damages during the base flood and create no additional threats to public safety.
B. SFHA Variance Notification. Any applicant to whom a SFHA variance is granted shall be given written notice that the issuance of a SFHA variance to construct a structure below the base flood elevation will result in increased premium rates for flood insurance and that such construction below the base flood elevation increases risks to life and property. Such notification and a record of all SFHA variance actions, including justification for their issuance, shall be maintained in accordance with section 2.10.800. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1400 Provisions for Flood Hazard Reduction
A. General Standards. In all special flood hazard areas, the following standards shall be adhered to:
1. Alteration of Watercourses. Require that the flood carrying capacity within the altered or relocated portion of said watercourse is maintained. Require that maintenance is provided within the altered or relocated portion of said watercourse to ensure that the flood carrying capacity is not diminished. Require compliance with sections 2.10.900.B and C.
2. Anchoring.
a. All new construction and substantial improvements 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 dwellings shall be anchored per section 2.10.2000.D.
3. 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.
B. Utilities and Equipment.
1. Water Supply, Sanitary Sewer, and On-Site Waste Disposal Systems.
a. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.
b. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters.
c. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding consistent with the Oregon Department of Environmental Quality.
2. Electrical, Mechanical, Plumbing, and Other Equipment. Electrical, heating, ventilating, air-conditioning, plumbing, duct systems, and other equipment and service facilities shall be elevated at or above the BFE level plus 1.0' or shall be designed and installed to prevent water from entering or accumulating within the components and to resist hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during conditions of flooding. In addition, electrical, heating, ventilating, air-conditioning, plumbing, duct systems, and other equipment and service facilities shall:
a. If replaced as part of a substantial improvement shall meet all the requirements of this section.
3. Tanks.
a. Underground tanks shall be anchored to prevent flotation, collapse and lateral movement under conditions of the base flood.
b. Above-ground tanks shall be installed at or above the BFE base flood level plus 1.0' or shall be anchored to prevent flotation, collapse, and lateral movement under conditions of the base flood. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1500 Subdivision Proposals and Other Proposed Developments
A. All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) greater than 50 lots or 5 acres, whichever is the lesser, shall include within such proposals, Base Flood Elevation data.
B. All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) shall:
1. Be consistent with the need to minimize flood damage.
2. Have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage.
3. Have adequate drainage provided to reduce exposure to flood hazards. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1600 Use of Other Base Flood Data
A. When Base Flood Elevation data has not been provided in accordance with section 2.10.400.B the local floodplain administrator shall obtain, review, and reasonably utilize any Base Flood Elevation data available from a federal, state, or other source, in order to administer sections 2.10.1400 through 2.10.2100. All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) must meet the requirements of section 2.10.1500.
B. Base Flood Elevations shall be determined for development proposals that are 5 acres or more in size or are 50 lots or more whenever there is not an established base flood elevation. Development proposals located within a riverine unnumbered A Zone shall be reasonably safe from flooding; the test of reasonableness includes use of historical data, high water marks, FEMA provided Base Level Engineering data, and photographs of past flooding, etc., where available, but at a minimum shall be at least 2 feet above the adjacent grade. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1700 Structures Located in Multiple or Partial Flood Zones
In coordination with the State of Oregon Specialty Codes:
A. When a structure is located in multiple flood zones on the community’s Flood Insurance Rate Maps (FIRM) the provisions for the more restrictive flood zone shall apply.
B. When a structure is partially located in a special flood hazard area, the entire structure shall meet the requirements for new construction and substantial improvements. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1800 Critical Facilities
Construction of new critical facilities shall be, to the extent possible, located outside the limits of the special flood hazard area. Construction of new critical facilities shall be permissible within the SFHA only if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor elevated three (3) feet above the base flood elevation (BFE) or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility shall 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. [Ord. 505 § 2 (Exh. B), 2020].
2.10.1900 Specific Standards for Riverine (Including All Non-Coastal) Flood Zones
These specific standards shall apply to all new construction and substantial improvements in addition to the General Standards contained in Section 2.10.1400(A)(1).
A. Flood Openings. All new construction and substantial improvements with fully enclosed areas below the lowest floor (excluding basements) are subject to the following requirements.
Enclosed areas below the Base Flood Elevation, including crawl spaces, shall:
1. Be designed to automatically equalize hydrostatic flood forces on walls by allowing for the entry and exit of floodwaters;
2. Be used solely for parking, storage, or building access;
3. Be certified by a registered professional engineer or architect or meet or exceed all of the following minimum criteria:
a. A minimum of two openings.
b. The total net area of non-engineered openings shall be not less than one (1) square inch for each square foot of enclosed area, where the enclosed area is measured on the exterior of the enclosure walls.
c. The bottom of all openings shall be no higher than one foot above grade.
d. Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, that they shall allow the automatic flow of floodwater into and out of the enclosed areas and shall be accounted for in the determination of the net open area.
e. All additional higher standards for flood openings in the State of Oregon Residential Specialty Codes Section R322.2.2 shall be complied with when applicable.
B. Garages.
1. Attached garages may be constructed with the garage floor slab below the Base Flood Elevation (BFE) in riverine flood zones, if the following requirements are met:
a. If located within a floodway the proposed garage must comply with the requirements of section 2.10.2100;
b. The floors are at or above grade on not less than one side;
c. The garage is used solely for parking, building access, and/or storage;
d. The garage is constructed with flood openings in compliance with this section to equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater;
e. The portions of the garage constructed below the BFE are constructed with materials resistant to flood damage;
f. The garage is constructed in compliance with the standards in section 2.10.1400.A; and
g. The garage is constructed with electrical and other service facilities located and installed so as to prevent water from entering or accumulating within the components during conditions of the base flood.
2. Detached garages must be constructed in compliance with the standards for appurtenant structures in section 2.10.2000.F or non-residential structures in section 2.10.2000.C depending on the square footage of the garage. [Ord. 505 § 2 (Exh. B), 2020].
2.10.2000 Specific Standards for Riverine (Non-Coastal) Special Flood Hazard Areas with Base Flood Elevations
In addition to the general standards listed in section 2.10.1400.A the following specific standards shall apply in Riverine (non-coastal) special flood hazard areas with Base Flood Elevations (BFE): Zones A1-A30, AH, and AE.
A. Before Regulatory Floodway. In areas where a regulatory floodway has not been designated, no new construction, substantial improvement, or other development (including fill) shall be permitted within Zones A1-30 and AE on the community’s Flood Insurance Rate Map (FIRM), unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the community.
B. Residential Construction.
1. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated at or above the Base Flood Elevation (BFE) plus 1.0'.
2. Enclosed areas below the lowest floor shall comply with the flood opening requirements in section 2.10.1900.A.
C. Non-Residential Construction.
1. New construction and substantial improvement of any non-residential structure shall:
a. Have the lowest floor, including basement elevated at or above one (1) foot above the Base Flood Elevation (BFE);
Or, together with attendant utility and sanitary facilities,
b. Be floodproofed so that below the base flood elevation level the structure is watertight with walls substantially impermeable to the passage of water;
c. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
d. 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 section based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the Floodplain Administrator as set forth in section 2.10.1900.
2. Non-residential structures that are elevated, not floodproofed, shall comply with the standards for enclosed areas below the lowest floor in section 2.10.1900.
3. Applicants floodproofing non-residential buildings shall be notified that flood insurance premiums will be based on rates that are one (1) foot below the floodproofed level (e.g., a building floodproofed to the base flood level will be rated as one (1) foot below that level).
4. Applicants shall supply a maintenance plan for the entire structure to include but not limited to: exterior envelope of structure; all penetrations to the exterior of the structure; all shields, gates, barriers, or components designed to provide floodproofing protection to the structure; all seals or gaskets for shields, gates, barriers, or components; and, the location of all shields, gates, barriers, and components, as well as all associated hardware, and any materials or specialized tools necessary to seal the structure.
5. Applicants shall supply an Emergency Action Plan (EAP) for the installation and sealing of the structure prior to a flooding event that clearly identifies what triggers the EAP and who is responsible for enacting the EAP.
D. Manufactured Dwellings.
1. New or substantially improved manufactured dwellings supported on solid foundation walls shall be constructed with flood openings that comply with section 2.10.1900.A;
2. The bottom of the longitudinal chassis frame beam shall be at or above Base Flood Elevation;
3. New or substantially improved manufactured dwellings shall be anchored to prevent flotation, collapse, and lateral movement during the base flood. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors. (Reference FEMA’s “Manufactured Home Installation in Flood Hazard Areas” guidebook for additional techniques), and;
4. Electrical crossover connections shall be a minimum of twelve (12) inches above Base Flood Elevation (BFE).
E. Recreational Vehicles. Recreational vehicles placed on sites are required to:
1. Be on the site for fewer than 180 consecutive days, fully licensed and ready for highway use, on its wheels or jacking system, be attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or
2. Meet the requirements of subsection (D) of this section, including the anchoring and elevation requirements for manufactured dwellings.
F. Appurtenant (Accessory) Structures. Relief from elevation or floodproofing requirements for residential and non-residential structures in riverine (non-coastal) flood zones may be granted for appurtenant structures that meet the following requirements:
1. Appurtenant structures located partially or entirely within the floodway must comply with requirements for development within a floodway found in section 2.10.2100.
2. Appurtenant structures must only be used for parking, access, and/or storage and shall not be used for human habitation.
3. In compliance with State of Oregon Specialty Codes, appurtenant structures on properties that are zoned residential are limited to one-story structures less than 200 square feet, or 400 square feet if the property is greater than two (2) acres in area and the proposed appurtenant structure will be located a minimum of 20 feet from all property lines. Appurtenant structures on properties that are zoned as non-residential are limited in size to 120 square feet.
4. The portions of the appurtenant structure located below the Base Flood Elevation must be built using flood resistant materials.
5. The appurtenant structure must be adequately anchored to prevent flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy, during conditions of the base flood.
6. The appurtenant structure must be designed and constructed to equalize hydrostatic flood forces on exterior walls and comply with the requirements for flood openings in section 2.10.1900.A.
7. Appurtenant structures shall be located and constructed to have low damage potential.
8. Appurtenant structures shall not be used to store toxic material, oil, or gasoline, or any priority persistent pollutant identified by the Oregon Department of Environmental Quality unless confined in a tank installed in compliance with section 2.10.1400.B(3).
9. Appurtenant structures shall be constructed with electrical, mechanical, and other service facilities located and installed so as to prevent water from entering or accumulating within the components during conditions of the base flood.
G. Below-Grade Crawl Spaces.
1. The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Hydrostatic loads and the effects of buoyancy can usually be addressed through the required flood openings stated in Section 2.10.1900.A. Because of hydrodynamic loads, crawl space construction is not allowed in areas with flood velocities greater than five (5) feet per second unless the design is reviewed by a qualified design professional, such as a registered architect or professional engineer. Other types of foundations are recommended for these areas.
2. The crawl space is an enclosed area below the Base Flood Elevation (BFE) and, as such, must have openings that equalize hydrostatic pressures by allowing the automatic entry and exit of floodwaters. The bottom of each flood vent opening can be no more than one (1) foot above the lowest adjacent exterior grade.
3. Portions of the building below the BFE must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawl space used to elevate the building, but also any joists, insulation, or other materials that extend below the BFE. The recommended construction practice is to elevate the bottom of joists and all insulation above BFE.
4. Any building utility systems within the crawl space must be elevated above BFE or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions. Ductwork, in particular, must either be placed above the BFE or sealed from floodwaters.
5. The interior grade of a crawl space below the BFE must not be more than two (2) feet below the lowest adjacent exterior grade.
6. The height of the below-grade crawl space, measured from the interior grade of the crawl space to the top of the crawl space foundation wall must not exceed four (4) feet at any point. The height limitation is the maximum allowable unsupported wall height according to the engineering analyses and building code requirements for flood hazard areas.
7. There must be an adequate drainage system that removes floodwaters from the interior area of the crawl space. The enclosed area should be drained within a reasonable time after a flood event. The type of drainage system will vary because of the site gradient and other drainage characteristics, such as soil types. Possible options include natural drainage through porous, well-drained soils and drainage systems such as perforated pipes, drainage tiles or gravel or crushed stone drainage by gravity or mechanical means.
8. The velocity of floodwaters at the site shall not exceed five (5) feet per second for any crawl space. For velocities in excess of five (5) feet per second, other foundation types should be used. [Ord. 505 § 2 (Exh. B), 2020].
2.10.2100 Floodways
Located within the special flood hazard areas established in section 2.10.400.B are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of the floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply:
A. Prohibit encroachments, including fill, new construction, substantial improvements, and other development within the adopted regulatory floodway unless:
1. Certification by a registered professional civil engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment shall not result in any increase in flood levels within the community during the occurrence of the base flood discharge; or
2. A community may permit encroachments within the adopted regulatory floodway that would result in an increase in base flood elevations; provided, that a Conditional Letter of Map Revision (CLOMR) is applied for and approved by the Federal Insurance Administrator, and the requirements for such revision as established under Volume 44 of the Code of Federal Regulations, section 65.12 are fulfilled.
3. If an encroachment proposal resulting in an increase in Base Flood Elevation meets the following criteria:
a. Is for the purpose of fish enhancement,
b. Does not involve the placement of any structures (as defined in section 2.10.300) within the floodway,
c. Has a feasibility analysis completed documenting that fish enhancement will be achieved through the proposed project,
d. Has a maintenance plan in place to ensure that the stream carrying capacity is not impacted by the fish enhancement project,
e. Has approval by the National Marine Fisheries Service, the State of Oregon Department of Fish and Wildlife, or the equivalent federal or state agency, and
f. Has evidence to support that no existing structures will be negatively impacted by the proposed activity;
Then an approved CLOMR may be required prior to approval of a floodplain permit.
B. If the requirements of subsection (A) of this section are satisfied, all new construction, substantial improvements, and other development shall comply with all other applicable flood hazard reduction provisions of sections 2.10.1400 through 2.10.2100. [Ord. 505 § 2 (Exh. B), 2020].
Prior legislation: Ord. 486.