Chapter 15.16
FLOOD DAMAGE PREVENTION
Sections:
Article I. Purpose, Applicability, Authority, Findings
15.16.110 Purpose.
15.16.115 Applicability.
15.16.120 Statutory authorization.
15.16.125 Findings of fact.
15.16.130 Methods of reducing flood losses.
Article II. Definitions
15.16.200 Definitions.
Article III. General Provisions
15.16.310 Basis for establishing areas of special flood hazard and floodways.
15.16.315 Compliance with chapter required.
15.16.320 Abrogation and greater restrictions.
15.16.325 Interpretation.
15.16.330 Warning and disclaimer of liability.
15.16.335 Severability.
Article IV. Administration
15.16.410 Establishment of development permit for flood hazard zones.
15.16.415 Designation of local floodplain administrator.
15.16.420 Local floodplain administrator – Duties generally.
15.16.425 Permit review.
15.16.430 Use of other base flood data.
15.16.435 Information to be obtained and maintained.
15.16.440 Alteration of watercourses.
15.16.445 Interpretation of FIRM boundaries.
15.16.450 Appeal board.
15.16.455 Conditions for variances.
Article V. Provisions for Flood Hazard Reduction
15.16.510 Generally.
15.16.515 Anchoring.
15.16.520 Construction materials and methods.
15.16.525 Utilities.
15.16.530 Subdivision proposals.
15.16.535 Review of building permits.
15.16.540 Specific standards.
15.16.545 Residential construction.
15.16.550 Nonresidential construction.
15.16.555 Manufactured homes.
15.16.560 Recreational vehicles.
15.16.565 Critical facilities.
15.16.570 Below-grade crawlspaces.
Article VI. Regulations by Location
15.16.610 Before the regulatory floodway.
15.16.615 Floodways.
15.16.620 Standards for shallow flooding areas (AO zones).
15.16.625 Coastal high hazard areas.
Article I. Purpose, Applicability, Authority, Findings
15.16.110 Purpose.
It is the purpose of this chapter to promote the public health, safety and general welfare, and to minimize public and private losses due to flood conditions in specific areas by provisions designed to:
A. Protect human life and health;
B. Minimize expenditure of public money and costly flood control projects;
C. Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;
D. Minimize prolonged business interruptions;
E. Minimize damage to public facilities and utilities, such as water and gas mains; electric, telephone and sewer lines; and streets and bridges located in areas of special flood hazard;
F. Help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard, so as to minimize future flood blight areas;
G. Ensure that potential buyers are notified that property is in an area of special flood hazard; and
H. Ensure that those who occupy the areas of special flood hazard assume responsibility for their actions. (Ord. 2009-17 § 1 (Exh. A))
15.16.115 Applicability.
This chapter shall apply to all areas of special flood hazards and all areas of shallow flooding within the jurisdiction of the city. (Ord. 2009-17 § 1 (Exh. A))
15.16.120 Statutory authorization.
The legislature of the state has, in ORS 221.410, delegated the responsibility to local governmental units to adopt regulations designed to promote the public health, safety and general welfare of its citizenry. (Ord. 2009-17 § 1 (Exh. A))
15.16.125 Findings of fact.
A. The flood hazard areas of the city are subject to periodic inundation which results 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.
B. These flood losses are caused by the cumulative effect of obstructions in areas of special flood hazards, which increase flood heights and velocities and, when inadequately anchored, damage uses in other areas. Uses that are inadequately floodproofed, elevated or otherwise protected from flood damage also contribute to the flood loss. (Ord. 2009-17 § 1 (Exh. A))
15.16.130 Methods of reducing flood losses.
In order to accomplish its purposes, this chapter includes methods and provisions for:
A. Restricting or prohibiting uses that are dangerous to health, safety and property due to water or erosion hazards, or that result in damaging increases in erosion or flood heights or velocities;
B. Requiring that uses 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 that help accommodate or channel floodwaters;
D. Controlling filling, grading, dredging and other development that may increase flood damage; and
E. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or that may increase flood hazards in other areas. (Ord. 2009-17 § 1 (Exh. A))
Article II. Definitions
15.16.200 Definitions.
Unless specifically defined in this section, words or phrases used in this chapter shall be interpreted so as to give them the meaning they have in common usage and to give this chapter its most reasonable application.
“Appeal” means a request for a review of the planning and community development director’s or designee’s interpretation of any provision of this chapter, or a request for a variance.
“Area of shallow flooding” means a designated AO or AH zone on the Flood Insurance Rate Map (FIRM). The base flood depths range from one to three feet; a clearly defined channel does not exist; the path of flooding is unpredictable and indeterminate; and velocity flow may be evident. AO is characterized as sheet flow and AH indicates ponding.
“Area of special flood hazard” means the land in the floodplain within a community subject to a one percent or greater chance of flooding in any given year. Designation on maps always includes the letters A or V.
“Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year, also referred to as the “100-year flood.” Designation on maps always includes the letters A or V.
“Basement” means any area of the building having its floor subgrade (below ground level) on all sides.
“Below-grade crawlspace” 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 crawlspace to the top of the crawlspace foundation, does not exceed four feet at any point.
“Breakaway walls” means any type of walls, whether solid or lattice, and whether constructed of concrete, masonry, wood, metal, plastic or any other suitable building materials, which are not part of the structural support of the building and which are so designed as to break away, under abnormally high tides or wave action, without damage to the structural integrity of the building on which they are used or any buildings to which they might be carried by floodwaters.
“Coastal high hazard area” means the area subject to high-velocity waters, including, but not limited to, storm surge or tsunamis. The area is designated on a FIRM as V1-30, V and VE.
“Development” means any manmade change to improved real estate, including, but not limited to, buildings or other structures, mining, dredging, filling, grading, paving, storage of equipment and materials, excavation or drilling operations located within the area of special flood hazard.
“Flood” or “flooding” means a general and temporary condition of partial or complete inundation of normally dry land areas from:
A. The overflow of inland or tidal waters; and/or
B. The unusual and rapid accumulation of runoff of surface waters from any source.
“Flood Insurance Rate Map” (“FIRM”) means the official map on which the Federal Insurance Administration has delineated both the areas of special flood hazards and the risk premium zones applicable to the community.
“Flood insurance study” means the official report provided by the Federal Insurance Administration that includes flood profiles, the flood boundary and floodway map, and the water surface elevation of the base flood.
“Floodway” means 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 one foot.
“Lowest floor” means 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 found at LCMC 15.16.550.
“Manufactured home” means a structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when connected to the required utilities. For floodplain management purposes, the term “manufactured home” also includes park trailers, travel trailers and other similar vehicles placed on a site for greater than 180 consecutive days. For insurance purposes, the term “manufactured home” does not include park trailers, travel trailers and other similar vehicles.
“Manufactured home park or subdivision” means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
A. “Existing manufactured home park or subdivision” means a manufactured home park subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is completed before the effective date of the adopted floodplain management regulations, and is distinguished from a new manufactured home park or subdivision, for which the construction of such facilities is completed on or after the effective date of adopted floodplain management regulations.
B. “Expansion to an existing manufactured home park or subdivision” means the construction of facilities for servicing additional lots on which the manufactured homes are to be affixed (including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads).
“Mean sea level” means the average height of the sea for all stages of the tide.
“New construction” means structures for which the start of construction commenced on or after the effective date of the ordinance codified in this chapter and includes any subsequent improvements to a structure that already meets the definition of “new construction.”
“Permanent foundation” refers to a natural or manufactured support system to which a structure is anchored or attached. A permanent foundation is capable of resisting flood forces and may include posts, piles, poured concrete or reinforced block walls, properly compacted fill or other systems of comparable flood resistivity and strength.
“Recreational vehicle” means a vehicle which is:
A. Built on a single chassis;
B. Four hundred square feet or less when measured at the largest horizontal projection;
C. Designed to be self-propelled or permanently able to be towed by a light duty truck; and
D. Designed primarily not for use as a permanent dwelling, but as temporary living quarters for recreational, camping, travel, or seasonal use.
Special Flood Hazard. See “Area of special flood hazard.”
“Start of construction” includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, placement or other improvement was within 180 days of the permit date. The “actual start” means either the first placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; or the placement of a manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers or foundation 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” means a walled and roofed building, including a gas or liquid storage tank, that is principally above ground.
“Substantial damage” pertains to flood-related damage where the cost of restoring the structure would equal or exceed 50 percent of the market value of the structure before the damage occurred.
“Substantial improvement” means any repair, reconstruction or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure either (A) before the improvement or repair is started, or (B) if the structure has been damaged and is being restored, before the damage occurred. For the purpose of this definition, “substantial improvement” is considered to occur when the first alteration of any wall, ceiling, floor or other structural part of the building commences, whether or not that alteration affects the external dimensions of the structure. The term does not, however, include either (A) any project for improvement of a structure to comply with existing state or local health, sanitary or safety code specifications which are solely necessary to assure safe living conditions, or (B) any alteration of a structure listed on the National Register of Historic Places or a state inventory of historic places.
“Variance” means a grant of relief from the requirements of this chapter, which permits construction in a manner that would otherwise be prohibited by this chapter. (Ord. 2009-17 § 1 (Exh. A))
Article III. General Provisions
15.16.310 Basis for establishing areas of special flood hazard and floodways.
The areas of special flood hazard identified by the Federal Insurance Administration in a scientific and engineering report entitled “The Flood Insurance Study for Lincoln County,” dated December 18, 2009, with accompanying Flood Insurance Rate Maps, are adopted by reference and declared to be a part of this chapter. The Flood Insurance Study is on file at the planning and community development department at City Hall. The best available information for flood hazard area identification, as outlined in LCMC 15.16.430, shall be the basis for regulation until a new FIRM is issued that incorporates the data utilized under LCMC 15.16.430. (Ord. 2009-17 § 1 (Exh. A))
15.16.315 Compliance with chapter required.
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. (Ord. 2009-17 § 1 (Exh. A))
15.16.320 Abrogation and greater restrictions.
This chapter is not intended to repeal, abrogate or impair any existing easements, covenants or deed restrictions. However, where this chapter and another ordinance, easement, covenant or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail. (Ord. 2009-17 § 1 (Exh. A))
15.16.325 Interpretation.
In the interpretation and application of this chapter, all provisions shall be:
A. Considered as minimum requirements;
B. Liberally construed in favor of the governing body; and
C. Deemed neither to limit nor repeal any other powers granted under state statutes. (Ord. 2009-17 § 1 (Exh. A))
15.16.330 Warning and disclaimer of liability.
The degree of flood protection required by this chapter is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on rare occasions. Flood heights may be increased by manmade or natural causes. This chapter does not imply that land outside the areas of special flood hazards or uses permitted within such areas will be free from flooding or flood damages. This chapter shall not create liability on the part of the city, any officer or employee thereof, or the Federal Insurance Administration, for any flood damages that result from reliance on this chapter or any administrative decision lawfully made thereunder. (Ord. 2009-17 § 1 (Exh. A))
15.16.335 Severability.
If any provision of this chapter is held to be invalid or unconstitutional by a court of competent jurisdiction, the invalid provision shall be severed and the remaining valid provisions shall continue in full force and effect. (Ord. 2009-17 § 1 (Exh. A))
Article IV. Administration
15.16.410 Establishment of development permit for flood hazard zones.
All construction or development within any area of special flood hazard established in LCMC 15.16.310 requires a permit to be obtained in advance of the project. The permit shall be for all structures, including mobile homes, as defined in LCMC 15.16.200, and for all other development, including fill and other activities, also as defined in LCMC 15.16.200. Application for a development permit shall be made on forms furnished by the planning and community development director or designee and may include, but not be limited to: plans in duplicate drawn to scale showing the nature, location, dimensions and elevations of the area in question; existing or proposed structures; fill; storage of materials; and drainage facilities. Specifically, the following information is required:
A. Elevation, in relation to mean sea level, of the lowest floor (including basement) of all structures;
B. Elevation, in relation to mean sea level, to which any structure has been floodproofed;
C. Certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet the floodproofing criteria in LCMC 15.16.550; and
D. Description of the extent to which any watercourse will be altered or relocated as a result of proposed development. (Ord. 2009-17 § 1 (Exh. A))
15.16.415 Designation of local floodplain administrator.
The planning and community development director is appointed to administer and implement this chapter by granting or denying development permit applications in accordance with its provisions. (Ord. 2009-17 § 1 (Exh. A))
15.16.420 Local floodplain administrator – Duties generally.
The duties of the local floodplain administrator shall include, but not be limited to, those set forth in LCMC 15.16.425 through 15.16.445. (Ord. 2009-17 § 1 (Exh. A))
15.16.425 Permit review.
The local floodplain administrator shall review all development permits to determine:
A. That the permit requirements of this chapter have been satisfied;
B. That all necessary permits have been obtained from those federal, state or local governmental agencies from which prior approval is required;
C. Whether the proposed development is located in the floodway. If located in the floodway, the local floodplain administrator shall ensure that the encroachment provisions of LCMC 15.16.615, Floodways, are met. (Ord. 2009-17 § 1 (Exh. A))
15.16.430 Use of other base flood data.
When base flood elevation data has not been provided in accordance with LCMC 15.16.310, the local floodplain administrator shall obtain, review and reasonably utilize any base flood elevation and floodway data available from a federal, state or other source in order to administer Article V of this chapter through LCMC 15.16.625. (Ord. 2009-17 § 1 (Exh. A))
15.16.435 Information to be obtained and maintained.
Where base flood elevation data is provided through the flood insurance study, FIRM, or required as in LCMC 15.16.430, the local floodplain administrator is responsible for obtaining and maintaining the following information for public inspection:
A. The actual, as-built elevation (in relation to mean sea level) of the lowest floor, including basement and below-grade crawlspaces, of all new or substantially improved structures;
B. Whether the structure contains a basement;
C. The floodproofing certifications required in LCMC 15.16.410(C) and the actual elevation in relation to mean sea level to which the structure was floodproofed;
D. All other records pertaining to the provisions of this chapter. (Ord. 2009-17 § 1 (Exh. A))
15.16.440 Alteration of watercourses.
The local floodplain administrator shall:
A. Notify adjacent communities and the Oregon Department of Land Conservation and Development prior to any alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administration;
B. Require that maintenance be provided within the altered or relocated portion of such watercourse so that the flood-carrying capacity is not diminished. (Ord. 2009-17 § 1 (Exh. A))
15.16.445 Interpretation of FIRM boundaries.
The local floodplain administrator shall make interpretations, where needed, as to exact location of the boundaries of the areas of special flood hazards (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 have a reasonable opportunity to appeal the interpretation, as provided in LCMC 15.16.450. (Ord. 2009-17 § 1 (Exh. A))
15.16.450 Appeal board.
A. The city planning commission, as established by the city, shall hear and decide appeals and requests for variances from the requirements of this chapter.
B. The city planning commission shall hear and decide appeals when it is alleged there is an error in any requirement, decision or determination made by the local floodplain administrator in the enforcement or administration of this chapter.
C. Those aggrieved by the decision of the city planning commission, or any taxpayer, may appeal such decision as provided by law.
D. In passing upon such applications, the city planning commission shall consider all technical evaluations, all relevant factors, standards specified in other sections of this chapter, and:
1. The danger that materials may be swept onto other lands to the injury of others;
2. The danger to life and property due to flooding or erosion damage;
3. The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner;
4. The importance of the services provided by the proposed facility to the community;
5. The necessity to the facility of a waterfront location, where applicable;
6. The availability of alternative locations for the proposed use which are not subject to flooding or erosion damage;
7. The compatibility of the proposed use with existing and anticipated development;
8. The relationship of the proposed use to the comprehensive plan and floodplain management program for that area;
9. The safety of access to the property in times of flood for ordinary and emergency vehicles;
10. The expected heights, velocity, duration, rate of rise and sediment transport of the floodwaters and the effects of wave action, if applicable, expected at the site; and
11. The costs of providing governmental services during and after flood conditions, including maintenance and repair of public utilities and facilities such as sewer, gas, electrical and water systems and streets and bridges.
E. Upon consideration of the factors of subsection (D) of this section and the purposes of this chapter, the city planning commission may deny or approve applications for appeals or grant variances, attaching such conditions to the granting of variances as it deems necessary to further the purposes of this chapter. In addition to conditions attached to approval of a specific application, conditions in LCMC 15.16.455 apply.
F. The local floodplain administrator shall maintain the records of all appeal actions and report any variances to the Federal Insurance Administration upon request. (Ord. 2009-17 § 1 (Exh. A))
15.16.455 Conditions for variances.
A. Generally, the only condition under which a variance from the elevation standard may be issued is 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, providing the items set forth in LCMC 15.16.450(D) have been fully considered. As the lot size increases, the technical justification required for issuing the variance increases.
B. Variances may be issued for the reconstruction, rehabilitation or restoration of structures listed on the National Register of Historic Places or the State Inventory of Historic Places, without regard to the procedures set forth in this section.
C. Variances shall not be issued within a designated floodway if any increase in flood levels during the base flood discharge would result.
D. Variances shall only be issued upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.
E. Variances shall only be issued upon:
1. A showing of good and sufficient cause;
2. A determination that failure to grant the variance would result in exceptional hardship to the applicant;
3. A determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, or extraordinary public expense, create nuisances, cause fraud on or victimization of the public as identified in LCMC 15.16.450(D), or conflict with existing local laws and ordinances.
F. Variances as interpreted in the National Flood Insurance Program are based on the general zoning law principle that they pertain to a physical piece of property; they are not personal in nature and do not pertain to the structure, its inhabitants, or economic or financial circumstances. They primarily address small lots in densely populated residential neighborhoods. As such, variances from the flood elevations should be quite rare.
G. Variances may be issued for nonresidential buildings in very limited circumstances to allow a lesser degree of floodproofing than watertight or dry floodproofing, where it can be determined that such action will have low damage potential, complies with all other variance criteria except subsection (A) of this section, and otherwise complies with the general standards set forth in LCMC 15.16.515, Anchoring, 15.16.520, Construction materials and methods, and 15.16.525, Utilities.
H. Any applicant to whom a variance is granted shall be given written notice that the structure will be permitted to be built with a lowest floor elevation below the base flood elevation and that the cost of flood insurance will be commensurate with the increased risk resulting from the reduced lowest floor elevation. (Ord. 2009-17 § 1 (Exh. A))
Article V. Provisions for Flood Hazard Reduction
15.16.510 Generally.
In all areas of special flood hazards, the standards set forth in this article are required. (Ord. 2009-17 § 1 (Exh. A))
15.16.515 Anchoring.
A. All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure.
B. All manufactured homes must likewise be anchored to prevent flotation, collapse or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors (reference FEMA’s “Manufactured Home Installation in Flood Hazard Areas” guidebook for additional techniques). (Ord. 2009-17 § 1 (Exh. A))
15.16.520 Construction materials and methods.
A. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
B. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
C. Electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities shall be designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding. (Ord. 2009-17 § 1 (Exh. A))
15.16.525 Utilities.
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. (Ord. 2009-17 § 1 (Exh. A))
15.16.530 Subdivision proposals.
A. All subdivision proposals shall be consistent with the need to minimize flood damage.
B. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and so constructed as to minimize flood damage.
C. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage.
D. For subdivision proposals and other proposed developments that contain at least 50 lots or five acres, if base flood elevation data has not been provided or is not available from another authoritative source, the applicant shall be responsible for generating it. (Ord. 2009-17 § 1 (Exh. A))
15.16.535 Review of building permits.
Where elevation data is not available either through the flood insurance study or from another authoritative source (LCMC 15.16.430), the city shall review applications for building permits to ensure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. Failure to elevate at least two feet above grade in these zones may result in higher insurance rates. (Ord. 2009-17 § 1 (Exh. A))
15.16.540 Specific standards.
The provisions set forth in the following four sections (Residential construction, Nonresidential construction, Manufactured homes and Recreational vehicles) are required in all areas of special flood hazards where base flood elevation data has been provided as set forth in LCMC 15.16.310, basis for establishing the areas of special flood hazard (Zones A1-30, AH, and AE), or 15.16.430, use of other flood data (in A and V Zones). (Ord. 2009-17 § 1 (Exh. A))
15.16.545 Residential construction.
A. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, one foot or more above base flood elevation.
B. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:
1. A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided.
2. The bottom of all openings shall be no higher than one foot above grade.
3. Openings may be equipped with screens, louvers or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters. (Ord. 2009-17 § 1 (Exh. A))
15.16.550 Nonresidential construction.
New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, one foot or more above the base flood elevation; or, together with attendant utility and sanitary facilities, shall:
A. Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water;
B. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
C. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this section based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in LCMC 15.16.410;
D. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in LCMC 15.16.545(B), Residential construction; and
E. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building constructed to the base flood level will be rated as one foot below that level). (Ord. 2009-17 § 1 (Exh. A))
15.16.555 Manufactured homes.
A. All manufactured homes to be placed or substantially improved:
1. Outside of a manufactured home park or subdivision;
2. In a new manufactured home park or subdivision;
3. In an expansion to an existing manufactured home park or subdivision; or
4. In an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as the result of a flood;
shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is a minimum 18 inches (one and one-half feet) above the base flood elevation and securely anchored to an adequately anchored system in accordance with the provisions of LCMC 15.16.515(B).
B. Manufactured homes to be placed, or substantially improved, on sites in an existing manufactured home park or subdivision within Zones A1-30, AH, and AE on the community’s FIRM that are not subject to the provisions in subsection (A) of this section shall be elevated so that either:
1. The finished floor of the manufactured home is elevated to a minimum of 18 inches (one and one-half feet) above the base flood elevation; or
2. The manufactured home chassis is supported by reinforced piers, or other foundation elements of at least equivalent strength, that are no less than 36 inches (three feet) in height above grade and securely anchored to an adequately designed foundation system to resist flotation, collapse, and lateral movement.
3. Manufactured homes in floodways are regulated by LCMC 15.16.615. (Ord. 2009-17 § 1 (Exh. A))
15.16.560 Recreational vehicles.
Recreational vehicles placed on sites are required to either:
A. Be on the site for fewer than 180 consecutive days;
B. 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, with no permanently attached additions; or
C. Meet the elevation, anchoring and other requirements for manufactured homes in LCMC 15.16.555, Manufactured homes. (Ord. 2009-17 § 1 (Exh. A))
15.16.565 Critical facilities.
Construction of new critical facilities shall be, to the extent possible, located outside the limits of the special flood hazard area (SFHA) (i.e., 100-year floodplain). Construction of new critical facilities shall be permissible within the SFHA, if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor elevated three feet above BFE or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility also should be protected to the height utilized above. Floodproofing and sealing must ensure that toxic substances will not be displaced by or released into floodwaters. Access routes to all critical facilities shall be elevated to or above the level of the base flood elevation to the extent possible. (Ord. 2009-17 § 1 (Exh. A))
15.16.570 Below-grade crawlspaces.
Below-grade crawlspaces are allowed subject to the following standards as found in FEMA Technical Bulletin 11-01, “Crawlspace Construction for Buildings Located in Special Flood Hazard Areas.” Note: FEMA will add an additional charge to the basic flood insurance policy premium for a below-grade crawlspace.
A. 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 usually can be addressed through the required openings stated in subsection (B) of this section. Because of hydrodynamic loads, crawlspace construction is not allowed in areas with flood velocities greater than five 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.
B. The crawlspace 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 foot above the lowest adjacent exterior grade.
C. 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 crawlspace 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.
D. Any building utility systems within the crawlspace 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.
E. The interior grade of a crawlspace below the BFE must not be more than two feet below the lowest adjacent exterior grade.
F. The height of the below-grade crawlspace, measured from the interior grade of the crawlspace to the top of the crawlspace foundation wall, must not exceed four feet at any point. The height limitation is the maximum allowable unsupported wall height according to the engineering analyses and building code requirements for flood hazard areas.
G. An adequate drainage system must be in place to remove floodwaters from the interior area of the crawlspace 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.
H. The velocity of floodwaters at the site should not exceed five feet per second for any crawlspace. For velocities in excess of five feet per second, other foundation types should be used. (Ord. 2009-17 § 1 (Exh. A))
Article VI. Regulations by Location
15.16.610 Before the regulatory floodway.
In areas where a regulatory floodway has not been designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within Zones A1-30 and AE on the community’s FIRM, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the community. (Ord. 2009-17 § 1 (Exh. A))
15.16.615 Floodways.
Floodways designated in LCMC 15.16.310 are located within areas of special flood hazard. Since a floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply to floodways:
A. Encroachments, including fill, new construction, substantial improvements, and other development except as provided in subsection (C) of this section, are prohibited unless certification by a registered professional engineer or architect is provided, demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that encroachments will not result in any increase in flood levels during the occurrence of the base flood discharge.
B. If the certification required by subsection (A) of this section is provided, then all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions set out in the following sections: Article V of this chapter, Provisions for Flood Hazard Reduction, through LCMC 15.16.625, Coastal high hazard areas (V zones).
C. Projects for stream habitat restoration may be permitted in the floodway, provided:
1. The project qualifies for a Department of the Army, Portland District, regional general permit for stream habitat restoration (NWP-2007-1023); and
2. 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 100-year flood levels as close to zero as practically possible given the goals of the project; and
3. No structures would be impacted by a potential rise in flood elevation; and
4. An agreement to monitor the project, correct problems, and ensure that flood carrying capacity remains unchanged is included as part of the local approval.
D. New installation of manufactured dwellings in floodways is prohibited (as in the 2002 Oregon Manufactured Dwelling and Park Specialty Code). Manufactured dwellings may only be located in floodways according to one of the following conditions:
1. If the manufactured dwelling already exists in the floodway, the placement was permitted at the time of the original installation, and the continued use is not a threat to life, health, property, or the general welfare of the public; or
2. A new manufactured dwelling is replacing an existing manufactured dwelling whose original placement was permitted at the time of installation, the replacement home will not be a threat to life, health, property, or the general welfare of the public, and it meets the following criteria:
a. As required by 44 CFR Chapter 1, Subpart 60.3(d)(3), it must be demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practices that the manufactured dwelling and any accessory buildings, accessory structures, or any property improvements (encroachments) will not result in any increase in flood levels during the occurrence of the base flood discharge;
b. The replacement manufactured dwelling and any accessory buildings or accessory structures (encroachments) shall have the finished floor elevated a minimum of 18 inches (one and one-half feet) above the BFE as identified on the Flood Insurance Rate Map;
c. The replacement manufactured dwelling is placed and secured to a foundation support system designed by an Oregon professional engineer or architect and approved by the authority having jurisdiction;
d. The replacement manufactured dwelling, its foundation supports, and any accessory buildings, accessory structures, or property improvements (encroachments) do not displace water to the degree that it causes a rise in the water level or diverts water in a manner that causes erosion or damage to other properties;
e. The location of a replacement manufactured dwelling is allowed by the local planning department’s ordinances; and
f. Any other requirements deemed necessary by the authority having jurisdiction. (Ord. 2009-17 § 1 (Exh. A))
15.16.620 Standards for shallow flooding areas (AO zones).
Shallow flooding areas appear on FIRMs as AO zones with depth designations. The base flood depths in these zones range from one to three feet where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. In these areas, the following provisions apply:
A. New construction and substantial improvements of residential structures within AO zones shall have the lowest floor, including basement, elevated one foot or more above the depth number specified on the FIRM (at least two feet, if no depth number is specified), as measured from the highest grade adjacent to the building site.
B. New construction and substantial improvements of nonresidential structures within AO zones shall either:
1. Have the lowest floor, including basement, elevated one foot or more above the depth number specified on the FIRM (at least two feet if no depth number is specified), as measured from the highest grade adjacent to the building site; or
2. Together with attendant utility and sanitary facilities, be completely floodproofed to or above that level so that any space below that level is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect as in LCMC 15.16.550.
C. Adequate drainage paths shall be required around structures on slopes to guide floodwaters around and away from proposed structures. (Ord. 2009-17 § 1 (Exh. A))
15.16.625 Coastal high hazard areas.
Coastal high hazard areas designated as V1-30, VE and/or V, established in LCMC 15.16.310, basis, have special flood hazards associated with high-velocity waters from tidal surges and, therefore, in addition to meeting all provisions of this chapter, the following provisions shall also apply:
A. All new construction and substantial improvements in zones VE (V if base flood elevation data is available) shall be elevated on pilings and foundations so that:
1. The bottom of the lowest horizontal structure member of the lowest floor, excluding the pilings or columns, is elevated one foot or more above the base flood level; and
2. The pile or column foundation and structure attached thereto is anchored to resist flotation, collapse and lateral movement due to the effects of wind and water loads acting simultaneously on all building components. Wind and water loading values shall each have a one percent chance of being equaled or exceeded in any given year (100-year mean recurrence interval).
B. A registered professional engineer or architect shall develop or review the structural design, specifications and plans for the construction and shall certify that the design and methods of construction to be used are in accordance with accepted standards of practice for meeting the provisions of this section.
C. The elevation, in relation to mean sea level, of the lowest floor, excluding pilings and columns, of all new and substantially improved structures in zones V and VE shall be obtained; and it shall be ascertained whether or not such structures contain a basement. The planning and community development director shall maintain a record of all such information.
D. All new construction shall be located landward of the reach of mean high tide.
E. All new construction and substantial improvements shall have the space below the lowest floor either free of obstruction or constructed with nonsupporting breakaway walls, open wood latticework, or insect screening intended to collapse under wind and water loads without causing collapse, displacement or other structural damage to the elevated portion of the building or supporting foundation system. For the purpose of this section, a breakaway wall shall have a design safe loading resistance of not less than 10 and no more than 20 pounds per square foot. Use of breakaway walls which exceed a design safe loading resistance of 20 pounds per square foot, either by design or when so required by local or state codes, may be permitted only if a registered professional engineer or architect certifies that the designs proposed meet the following conditions:
1. Breakaway wall collapse shall result from a water load less than that which would occur during the base flood; and
2. The elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement or other structural damage due to the effects of wind and water loads acting simultaneously on all building components (structural and nonstructural). Maximum wind and water loading values to be used in this determination shall each have a one percent chance of being equaled or exceeded in any given year (100-year mean recurrence interval).
F. If breakaway walls are utilized, such enclosed space shall be usable solely for parking of vehicles, building access or storage. Such space shall not be used for human habitation.
G. The use of fill for structural support of buildings is prohibited.
H. Manmade alteration of sand dunes which would increase potential flood damage is prohibited.
I. For construction of new essential structures and new special occupancy structures, refer to ORS 455.446 and 455.447, which state that they may not be constructed in the tsunami inundation zone, which includes V, A, and potentially other flood zones. If an exception is granted, the coastal high hazard area construction standards in the model ordinance shall apply to the building of these new structures in the tsunami inundation zone. (Ord. 2009-17 § 1 (Exh. A))