Chapter 3.7
Floodplain Standards
Sections:
3.7.100 Purpose, Findings of Fact, and Applicability
3.7.130 Provisions for Flood Hazard Reduction
3.7.100 Purpose, Findings of Fact, and Applicability
A. Purpose. The purposes of this chapter are to:
1. Protect human life, health and property;
2. Minimize damage to public facilities and utilities such as water purification and sewage treatment plants, water and gas mains, electric, telephone and sewer lines, streets and bridges located in floodplains;
3. Help maintain a stable tax base by providing for the sound use and development of flood prone areas;
4. Minimize expenditure of public money for costly flood control projects;
5. Minimize the need for rescue and emergency services associated with flooding and generally undertaken at the expense of the general public;
6. Minimize unnecessary disruption of commerce, access and public service during times of flood;
7. Ensure that potential buyers are notified that property is in an area of special flood hazard;
8. Ensure that those who occupy the areas of special flood hazard assume responsibility for their actions;
9. Manage the alteration of flood hazard areas, and stream channels to minimize the impact of development on the natural and beneficial functions of the floodplain, and;
10. Implement the City’s Comprehensive Plan policies regarding development within the floodplain.
B. Findings of Fact. The following findings substantiate implementation of standards presented in this Chapter.
1. The flood hazard areas of the City of Halsey are subject to periodic inundation that results in loss of life and property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood relief and protection, and impairment of the tax base, all of which adversely affect the public health, safety and general welfare.
2. These flood losses are caused by structures in flood hazard areas, which are inadequately elevated, flood-proofed, or otherwise unprotected from flood damages, and by the cumulative effect of obstructions in floodplains causing increases in flood heights and velocities.
3. The City of Halsey has the primary responsibility for planning, adoption and enforcement of land use regulations to accomplish proper floodplain management.
C. Applicability. This ordinance shall apply to all Areas of Special Flood Hazard within the jurisdiction of the City of Halsey, as identified on the zoning map through the 100-year Floodplain Overlay and through Section 3.7.110.A. Nothing in this Ordinance is intended to allow uses or structures that are otherwise prohibited by the zoning ordinance or State Building Codes.
3.7.110 General Provisions
A. Basis for Areas of Special Flood Hazard. The Areas of Special Flood Hazard identified by the Federal Emergency Management Agency in its Flood Insurance Study (FIS) for Linn County, Oregon and Incorporated Areas, dated September 29, 2010, with accompanying Flood Insurance Rate Maps (FIRM) or Digital Flood Insurance Rate Maps (DFIRM), and other supporting data, are adopted by reference and declared a part of this ordinance. The FIS and the FIRM are on file at the office of the City Administrator at 773 West First Street, Halsey, Oregon 97348.
B. Methods of Reducing Flood Losses. In order to accomplish its purpose, this ordinance includes methods and provisions to:
1. Require that development that is vulnerable to floods, including structures and facilities necessary for the general health, safety and welfare of citizens, be protected against flood damage at the time of initial construction;
2. Restrict or prohibit uses which are dangerous to health, safety and property due to water or erosion hazards, or which increase flood heights, velocities, or erosion;
3. Control filling, grading, dredging and other development which may increase flood damage or erosion;
4. Prevent or regulate the construction of flood barriers that will unnaturally divert flood waters or that may increase flood hazards to other lands;
5. Preserve and restore natural floodplains, stream channels, and natural protective barriers which carry and store flood waters, and;
6. Coordinate with and supplement provisions of State Building Codes.
C. Coordination with Building Codes. Pursuant to the requirement established in ORS 455 that the City of Halsey administers and enforces the State Building Codes, the City Council of the City of Halsey does hereby acknowledge that the State Building Codes contain certain provisions that apply to the design and construction of buildings and structures located in Areas of Special Flood Hazard. Therefore, this ordinance is intended to be administered and enforced in conjunction with the State Building Codes.
D. Establishment of a Floodplain Development Permit. A Floodplain Development Permit shall be obtained prior to initiating Development activities in any Areas of Special Flood Hazard established by Section 3.7.100.C.
Any Floodplain Development Permit that requires an engineering certification or engineering analysis, calculations or modeling to process shall be considered as a Type II land use decision, in accordance with Chapter 4.2, Section 4.2.130, Type II Administrative Review. A Flood Development Permit will be a Type III Quasi-Judicial Review if the flood plain development permit is filed concurrently with another application which requires a Type III review.
1. Floodplain Development Permit Exemptions. The following types of Development are exempt from the Floodplain Development Permit process:
a. Construction of Fences and Walls within the Floodway Fringe. New and reconstructed fences are permitted within the Floodway Fringe and exempt from receiving Floodplain Development Permit approval, provided:
(1) An opening or a flap is provided in the areas at or below the Base Flood elevation at least once every two fence panels or 16 ft., whichever is less. The minimum dimensions of the opening or flap shall not be less than 12 in. x 12 or 8 in. x 18 in. In areas of the Floodway Fringe where Base Flood Elevation data is not available, the opening or flap shall be placed within one ft. of the existing grade along the fence alignment;
(2) Openings do not include any screening of any size or type; and
(3) When used, flaps are capable of self-release and open to the full dimensions when under pressure of no greater than 20 pounds per square foot.
b. Maintenance, Repair, and/or Replacement of Existing Public Infrastructure. Existing public infrastructure may be maintained, repaired, and/or replaced without approval of a Floodplain Development Permit provided:
(1) The activities are limited to in-kind maintenance, repair, and/or replacement; and
(2) No increase in the Base Flood Elevation results from the specified activity.
c. Signs, markers, aids, etc. placed by a public agency to serve the public.
d. Customary dredging associated with routine channel maintenance, provided it is consistent with State and Federal laws and permits.
e. Accessory residential or noncommercial structures less than 200 square feet in area.
E. Interpretation. In the interpretation and application of this ordinance 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, including State Building Codes.
F. Warning and Disclaimer of Liability. The degree of flood protection required by this ordinance is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur. Flood heights may be increased by man-made or natural causes. This ordinance does not imply that land outside Areas of Special Flood Hazard or uses permitted within such areas will be free from flooding or flood damages. This ordinance shall not create liability on the part of the City of Halsey or by any officer or employee thereof for flood damages that result from reliance on this ordinance or an administrative decision lawfully made hereunder.
3.7.120 Administration
A. Designation of a Floodplain Administrator. The City Administrator is hereby appointed as the Floodplain Administrator who is responsible for administering and implementing the provisions of this ordinance.
B. Duties and Responsibilities of the Administrator. Duties of the Floodplain Administrator shall include, but not be limited to:
1. Review all development permit applications to determine whether proposed new development or Substantial Improvement will be located in Areas of Special Flood Hazard;
2. Review applications for modifications of any existing development in Areas of Special Flood Hazard for compliance with the requirements of this ordinance;
3. Interpret flood hazard area boundaries, provide available flood hazard information, and provide Base Flood Elevations, where they exist;
4. Review proposed development to assure that necessary permits have been received from governmental agencies from which 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; the Endangered Species Act of 1973, 16 U.S.C. 1531-1544; and State of Oregon Removal-Fill permits. Copies of such permits shall be maintained on file;
5. Review all development permit applications to determine if the proposed development is located in the floodway, and if so, ensure that the encroachment standards of Section 3.7.130.B are met;
6. When Base Flood Elevation data or floodway data are not available, then the Floodplain Administrator shall obtain, review and reasonably utilize any Base Flood Elevation and floodway data available from a federal, state or other authoritative source in order to administer the provisions of this ordinance;
7. When Base Flood Elevations or other engineering data are not available from an authoritative source, the Floodplain Administrator shall take into account the flood hazards, to the extent they are known, to determine whether a proposed building site or subdivision will be reasonably safe from flooding. Note: Oregon Residential Specialty Code R324.1.3 authorizes the Building Official to require the applicant to determine a Base Flood Elevation where none exists.
8. Where interpretation is needed of the exact location of boundaries of the Areas of Special Flood Hazard including the regulatory floodway (for example, where there appears to be a conflict between a mapped boundary and actual field conditions), the Floodplain Administrator shall make the interpretation. Any person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation, as provided in Chapter 4.2, Section 4.2.130.F.
9. Issue floodplain development permits when the provisions of this ordinance have been met, or deny the same in the event of noncompliance;
10. Coordinate with the Building Official to assure that applications for building permits comply with the requirements of this ordinance;
11. Obtain, verify and record the actual elevation in relation to the vertical datum used on the effective FIRM, or highest adjacent grade where no Base Flood Elevation is available, of the lowest floor level, including basement, of all new construction or substantially improved buildings and structures.
12. Obtain, verify and record the actual elevation, in relation to the Vertical Datum used on the effective FIRM, or highest adjacent grade where no Base Flood Elevation is available, to which any new or substantially improved buildings or structures have been flood-proofed. When flood- proofing is utilized for a structure, the Floodplain Administrator shall obtain certification of design criteria from a registered professional engineer or architect;
13. Ensure that all records pertaining to the provisions of this Chapter are permanently maintained in the office of the city/county clerk or his/her designee and shall be open for public inspection.
14. Maintain a permanent record of all variances and report any variances to the Federal Emergency Management Agency upon request.
15. Make inspections in Areas of Special Flood Hazard to determine whether development has been undertaken without issuance of a Floodplain Development Permit, ensure that development is undertaken in accordance with the Floodplain Development Permit and this ordinance, and verify that existing buildings and structures maintain compliance with this ordinance;
16. Coordinate with the Building Official to inspect areas where buildings and structures in flood hazard areas have been damaged, regardless of the cause of damage, and notify owners that permits may be required prior to repair, rehabilitation, demolition, relocation, or reconstruction of the building or structure; and
17. Make Substantial Improvement or Substantial Damage determinations based on criteria set forth in Chapter 4.3, Section 4.3.140.B.10.j.
3.7.130 Provisions for Flood Hazard Reduction
A. Site Improvements and Subdivisions.
1. All proposed new development, Substantial Improvement, partitions, and subdivisions shall be consistent with the need to minimize flood damage and ensure that building sites will be reasonably safe from flooding.
2. Building lots shall have adequate buildable area outside of floodways.
3. New development proposals (including Substantial Development), partition development plans, and subdivision development plans shall include the mapped Flood Hazard Zones from the effective FIRM, if available.
4. Base Flood Elevation data shall be generated and/or provided for Substantial Improvement, partition proposals, subdivision proposals, and all other proposed development, including manufactured home parks and subdivisions, consistent with Section 4.3.140.B.10.f.
5. New development, Substantial Improvement, partitions, and subdivisions shall have public utilities and facilities such as sewer, gas, electric and water systems located and constructed to minimize flood damage.
6. On-site waste disposal systems shall be located and constructed to avoid functional impairment, or contamination from them, during flooding.
7. Partitions and subdivisions shall have adequate drainage provided to reduce exposure to flood hazards. In AO and AH Flood Hazard Zones, drainage paths shall be provided to guide floodwater around and away from all proposed and existing structures.
B. Development in Floodways.
1. Except as provided in Section 3.7.130.B.4, below, encroachments, including fill, new construction, substantial improvements, and other development are prohibited within the 1.0-ft. Floodway unless certification by a registered professional civil engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that such encroachment shall not result in any increase in flood levels during the occurrence of the Base Flood discharge.
2. Any fill allowed to be placed in the Floodway shall be designed to be stable under conditions of flooding, including rapid rise and rapid drawdown of floodwaters, prolonged inundation, and flood-related erosion and scour.
3. Applicants shall obtain a Conditional Letter of Map Revision (CLOMR) from FEMA before an encroachment, including fill, new construction, Substantial Improvement, and other development, into the Floodway is permitted that will cause any increase in the Base Flood Elevation.
4. Projects for stream habitat restoration may be permitted in the Floodway provided:
a. The project qualifies for a Department of the Army, Portland District Regional General Permit for Stream Habitat Restoration (NWP-2007-1023);
b. A qualified professional (a Registered Professional Engineer; or staff of NRCS; the county; or fisheries, natural resources, or water resources agencies) has provided a feasibility analysis and certification that the project was designed to keep any rise in Base Flood levels as close to zero as practically possible given the goals of the project;
c. No structures would be impacted by a potential rise in flood elevation; and,
d. An agreement to monitor the project, correct problems, and ensure that flood carrying capacity remains unchanged is included as part of the Floodplain Development Permit approval.
5. Fences shall not cause any rise in Base Flood Elevation and are subject to the no-rise and CLOMR provisions of Sections 3.7.130.B.1 and 3.7.130.B.3, above.
C. Flood Hazard Zones with Base Flood Elevations but No Floodway.
1. In areas within Flood Hazard Zones A1-30 and AE on the community’s FIRM with a Base Flood Elevation, or where a Base Flood Elevation is developed according to Section 4.3.140.B.10.f, but where no regulatory floodway has been designated, new construction, Substantial Improvements, or other development (including fill) shall be prohibited, 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.
2. Applicants of proposed projects that increase the Base Flood Elevation more than one foot should obtain from FEMA a Conditional Letter of Map Revision (CLOMR) before the project may be permitted.
D. Flood Hazard Zones without Base Flood Elevations. The following standards apply in riverine Areas of Special Flood Hazard where no Base Flood Elevation data have been provided (Approximate A Flood Hazard Zones):
1. When Base Flood Elevation or Floodway data have not been identified by FEMA in a Flood Insurance Study and /or Flood Insurance Rate Maps, the Floodplain Administrator shall obtain, review, and reasonably utilize scientific or historic Base Flood Elevation and Floodway data available from a federal, state, or other source, in order to administer this ordinance.
2. Where the Floodplain Administrator has obtained Base Flood Elevation data, Section 3.7.130.C and Sections 3.7.130.E through 3.7.130.M shall apply.
E. Building Design and Construction. Buildings and structures, including manufactured dwellings, within the scope of the State Building Codes, including repair of Substantial Damage and Substantial Improvement of such existing buildings and structures, shall be designed and constructed in accordance with the flood-resistant construction provisions of these codes, including but not limited to Section R324 of the Residential Specialty Code and Section 1612 of the Structural Specialty Code.
F. Manufactured Dwellings.
1. New and replacement manufactured dwellings are within the scope of the State Building Codes; and,
2. All new manufactured dwellings and replacement manufactured dwellings shall be installed using methods and practices which minimize flood damage and shall be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement. Methods of anchoring include, but are not limited to, use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.
G. Below Grade Crawlspaces. Below-grade crawlspace foundations are allowed, unless no Base Flood Elevations are available, provided that they conform to guidelines in FEMA TB 11-01, Crawlspace Construction for Structures Located in Special Flood Hazard Areas, applicable State Building Codes, and the following standards:
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 openings stated in “2.”, below. Because of hydrodynamic loads, crawlspace construction is not allowed in areas with flood velocities greater than five (5) cubic 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 crawlspace is an enclosed area below the Base Flood Elevation, 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 Base Flood Elevation must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawlspace used to elevate the building, but also any joists, insulation, or other materials that extend below the Base Flood Elevation. The recommended construction practice is to elevate the bottom of joists and all insulation above Base Flood Elevation.
4. Any building utility systems within the crawlspace must be elevated above the Base Flood Elevation or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions. Ductwork, in particular, must either be placed above the Base Flood Elevation or sealed from floodwaters.
5. The interior grade of a crawlspace below the Base Flood Elevation must not be more than two (2) feet below the lowest adjacent exterior grade.
6. The height of the below-grade crawlspace, measured from the interior grade of the crawlspace to the top of the crawlspace foundation wall must not exceed four (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 crawlspace. 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 should not exceed five (5) cubic feet per second for any crawlspace. For velocities in excess of five (5) cubic feet per second, other foundation types should be used.
H. Accessory Structures. Relief from the elevation or dry flood-proofing standards may be granted for an accessory structure containing no more than 100 square feet. Such a structure must meet the following standards:
1. It shall not be subject to the State Building Codes;
2. The accessory structure shall be located on the same property as a permitted primary use;
3. It shall not be used for human habitation and may be used solely for parking of vehicles or storage of items having low damage potential when submerged;
4. Toxic material, oil or gasoline, or any priority persistent pollutant identified by the Oregon Department of Environmental Quality shall not be stored below the Base Flood Elevation, unless confined in a tank installed in compliance with this ordinance;
5. It shall be constructed of flood resistant materials;
6. It shall be constructed and placed on the lot to offer the minimum resistance to the flow of floodwaters;
7. It shall be firmly anchored to prevent flotation;
8. Services such as electrical and heating equipment shall be elevated or flood-proofed to or above the Base Flood Elevation; and
9. It shall be designed to equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater. Designs for complying with this requirement must be certified by a licensed professional engineer or architect; or
a. provides 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 the higher of the exterior or interior grade or floor immediately below the opening; and
c. openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwater in both directions without manual intervention.
I. Recreational Vehicles. In all Areas of Special Flood Hazard, Recreational Vehicles that are an allowed use or structure under the zoning ordinance must either:
1. Be placed on the site for fewer than 180 consecutive days;
2. Be fully licensed and ready for highway use, on its wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached structures or addition, or
3. Meet all the requirements of Section 3.7.130.F, including the anchoring and elevation requirements.
J. Critical Facilities. Construction of new Critical Facilities shall be, to the extent possible, located outside the limits of Areas of Special Flood Hazard. Construction of new Critical Facilities shall be permissible within Areas of Special Flood Hazard if no feasible alternative site is available. Critical Facilities constructed within Areas of Special Flood Hazard shall have the lowest floor elevated three feet above Base Flood Elevation (or depth number in AO Flood Hazard Zones) or to the height of the 0.2 percent flood (i.e., 500-year), whichever is higher. Access to and from the Critical Facility should also be protected to the height utilized above. Flood-proofing and sealing measures must be taken to ensure that toxic substances or priority organic pollutants as defined by the Oregon Department of Environmental Quality will not be displaced by or released into floodwaters. Access routes elevated to or above the level of the Base Flood Elevation shall be provided to all Critical Facilities to the extent possible. Any grade transition necessary to achieve the access protection requirement shall be achieved outside of Areas of Special Flood Hazard. The Floodplain Administrator shall make the determination as to whether or not a Critical Facility’s access and siting have achieved this provision’s standard of “to the maximum extent possible.”
K. Tanks. In all Areas of Special Flood Hazard, the following provisions apply to storage tanks that are an allowed use or structure under the zoning ordinance.
1. Underground tanks in Areas of Special Flood Hazard shall be anchored to prevent flotation, collapse or lateral movement resulting from hydrostatic loads, including the effects of buoyancy assuming the tank is empty, during conditions of the design flood;
2. Above-ground tanks in Areas of Special Flood Hazard shall be:
a. Elevated to or above the Base Flood Elevation (or depth number in AO Flood Hazard Zones) and attached to a supporting structure that is designed to prevent flotation, collapse or lateral movement during conditions of the design flood; or be
b. Anchored or otherwise designed and constructed to prevent flotation, collapse or lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy assuming the tank is empty, during conditions of the design flood.
3. Tank inlets, fill openings, outlets and vents shall be:
a. A minimum of 2 feet above the Base Flood Elevation or fitted with covers designed to prevent the inflow of floodwater or outflow of the contents of the tank during conditions of the design flood; and
b. Anchored to prevent lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy, during conditions of the design flood.
L. On-site Sewage Systems. In all Areas of Special Flood Hazard, the following provisions apply to on- site sewage systems that are an allowed use or structure under the zoning ordinance.
1. Soil absorption systems shall be located outside of Areas of Special Flood Hazard. Where suitable soil absorption sites outside of the Areas of Special Flood Hazard are not available, the soil absorption site is permitted to be located within the Areas of Special Flood Hazard provided it is located to minimize the effects of inundation under conditions of the Base Flood.
2. Mound systems in Areas of Special Flood Hazard are prohibited.
M. Fences and Walls. New fencing and walls shall be designed to collapse under conditions of the Base Flood or to allow the passage of water by having flaps or openings in the areas at or below the Base Flood Elevation sufficient to allow flood water and associated debris to pass freely. The design standards in Table 3.7.100 shall apply to all fencing and walls erected within the Areas of Special Flood Hazard identified in Section 3.7.100.C. For those types of fencing and walls requiring adequate openings between the base and Base Flood Elevation, such openings shall be provided at least once every three fence panels or 24 feet, whichever is less. Fences less than 24 feet in length shall have at least one flap or opening in the areas at or below the Base Flood Elevation. The minimum dimensions of the flap or opening shall not be less than 12"x12" or 8"x18". Openings shall not include any screening of any type or size. If flaps are used, they may be secured to allow closure during normal use, but must be capable of self-release and opening to full dimensions when under pressure of no greater than 20 pounds per sq. ft.
Table 3.7.130.M - Fence and Wall Design Standards
|
Fence or Wall Type |
Floodway Fringe (Riverine) |
Floodway (Riverine) |
Shallow/ Sheet flow/ Ponding Zones (AO and AH) |
|---|---|---|---|
|
A |
Yes |
||
|
B |
Yes |
Yes, with limited cross channel fencing |
Yes |
|
C |
Design Review Required |
||
|
D |
Yes, if open at base to BFE |
No1 |
Yes, if open at base to BFE |
|
E |
Yes, if open at base to BFE |
No1 |
Yes, if open at base to BFE |
|
F |
Yes, if adequate openings at base to BFE |
No1 |
Yes, if adequate openings at base to BFE |
|
G |
Yes, if adequate openings at base to BFE |
No1 |
Yes, if adequate openings at base to BFE |
|
H |
Yes, if adequate openings at base to BFE |
No1 |
Yes, if adequate openings at base to BFE |
|
Fence/Wall Types: A Open barb or barbless wire. Open means no more than one horizontal strand per foot of height B Open pipe or rail fencing (e.g. corrals). Open means rails occupy less than 10% of the fence area and posts are spaced no closer than 8 feet apart. C Collapsible fencing; fence must be designed to collapse at design flood velocities D Other wire, pipe, or rail fencing (e.g. field fence, chicken wire, etc.) which does not meet open requirements above. E Chain link fencing F Continuous wood fencing G Masonry walls H Retaining walls, bulkheads Footnotes: 1 Unless shown, using FEMA-approved engineering/modeling standards, to cause no-rise in BFE. |
|||
N. Other Development in Non-coastal High Hazard Areas. All development in non-coastal high hazard areas (A Flood Hazard Zones) for which specific provisions are not specified in this ordinance or State Building Codes, shall:
1. Be located and constructed to minimize flood damage;
2. Be designed so as not to impede flow of flood waters under Base Flood conditions;
3. If located in a Floodway, meet the limitations of Section 3.7.130.B, above;
4. Be anchored to prevent flotation or lateral movement resulting from hydrostatic loads, including the effects of buoyancy, during conditions of the design flood;
5. Be constructed of flood damage-resistant materials;
6. Have electric service and or mechanical equipment elevated above the Base Flood Elevation (or depth number in AO Flood Hazard Zones), except for minimum electric service required to address life safety and electric code requirements.
O. Temporary Storage, Structures, and Bridges. A Floodplain Development Permit is required for construction or placement of temporary structures, temporary storage associated with non- residential uses, and temporary bridges located in Areas of Special Flood Hazard:
1. Temporary structures, not including bridges, shall be limited as to time of service, but shall not be permitted for more than 90 days. The Floodplain Administrator is authorized to grant extensions for demonstrated cause; such cause shall reaffirm the temporary nature of the structure. Temporary structures shall be anchored to prevent flotation, collapse, or lateral movement.
2. Temporary storage of 50 cubic yards or more shall be limited as to time of service but shall not be permitted for more than 90 days. The Floodplain Administrator is authorized to grant extensions for demonstrated cause; such cause shall reaffirm the temporary nature of the storage. Stored material shall be anchored or contained to prevent flotation or release outside the assigned storage area. Hazardous materials priority persistent pollutants identified by the Oregon Department of Environmental Quality shall not be stored in the Floodway.
3. Temporary encroachments in the Floodway (including bridges) require a Floodplain Development Permit subject to conditions “a.” through “g.”, below. No CLOMR/LOMR is required.
a. The Floodplain Development Permit shall stipulate the days and dates the structure or other development will be on site based on the existing and expected hydrologic conditions within the Floodway. If a longer period is required, a new permit shall be issued.
b. A flood warning plan for the project shall be in place to allow equipment to be evacuated from the site and placed outside the Floodplain.
c. Placement of equipment in the Floodway shall be restricted to only that equipment which is absolutely necessary for the purposes of the project. All other accessory equipment and temporary structures (i.e. construction trailers) shall be restricted from the Floodway. Structures shall be placed on site so that flood damages are minimized.
d. Temporary changes to the Floodplain under a one (1) percent chance flood event (100-year Flood) shall be identified.
e. All insurable structures affected by any increase in Base Flood Elevation during a one (1) percent chance flood event (100-year Flood) shall be identified.
f. The applicant shall be notified that they may be liable for any flood damages resulting from the temporary structure.
P. Watercourse Alterations. A water course is considered altered when any change occurs within its banks, including installation of new culverts and bridges, or size modifications to existing culverts and bridges (as shown on effective FIRM).
1. The bankfull flood carrying capacity of the altered or relocated portion of the water course shall not be diminished. Prior to issuance of a Floodplain Development Permit, the applicant must submit a description of the extent to which any water course will be altered or relocated as a result of the proposed development and submit certification by a registered professional engineer that the bankfull flood carrying capacity of the water course will not be diminished.
2. Adjacent communities, the U.S. Army Corps of Engineers, Oregon Department of State Lands, and Oregon Department of Land Conservation and Development must be notified prior to any alteration or relocation of a water course. Evidence of notification must be submitted to the Floodplain Administrator and to the Federal Emergency Management Agency.
3. The applicant shall be responsible for providing the necessary maintenance for the altered or relocated portion of the water course so that the flood carrying capacity will not be diminished.
4. The applicant shall meet the requirements to submit technical data in Sections 4.3.140.B.10.h when an alteration of a watercourse, including the placement of culverts, results in the relocation or elimination of Areas of Special Flood Hazard.
Q. Non-conversion of Enclosed Areas below the Lowest Floor. To ensure that the areas below the Base Flood Elevation continue to be used solely for parking vehicles, limited storage, or access to the building and not be finished for use as human habitation without first becoming fully compliant with the floodplain management ordinance in effect at the time of conversion, the Floodplain Administrator shall:
1. Determine which applicants for new construction and/or substantial improvements have fully enclosed areas below the lowest floor that are five (5) feet or higher;
2. Enter into a “NON-CONVERSION AGREEMENT FOR CONSTRUCTION WITHIN FLOOD HAZARD AREAS” or equivalent with the City of Halsey. The agreement shall be recorded with the Linn County as a deed restriction. The non-conversion agreement shall be reviewed and approved by the Floodplain Administrator; and
3. Have the authority to inspect any area of a structure below the Base Flood Elevation to ensure compliance upon prior notice of at least 72 hours.