2.7.640 Floodplain Combining Zone | Bend Development Code

2.7.640 Floodplain Combining Zone.

A. Purpose. It is the purpose of this zone 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:

1. To protect human life and health;

2. To minimize expenditure of public money and costly flood control projects;

3. To minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;

4. To minimize prolonged business interruptions;

5. To 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 hazard;

6. To help maintain a stable tax base by providing for the sound use and development of areas of special flood hazards so as to minimize future flood blight areas;

7. To ensure that potential buyers are notified that property is in an area of special flood hazard; and

8. To ensure that those who occupy the areas of special flood hazard assume responsibility for their actions.

1. The FP Combining Zone shall apply to the areas identified on the Flood Insurance Rate Map (FIRM) as special flood hazard areas inundated by 100-year flood and floodway areas. The FIA Flood Insurance Study for “Deschutes County, Oregon and Incorporated Areas” and the FIRM map dated September 28, 2007, are hereby adopted and by this reference included herein. The Flood Insurance Study is on file at the Planning Division. The A and AE Zones shown on the FIRM map are hereby zoned FP.

2. The Planning Director is hereby appointed to administer and implement the Floodplain Combining Zone by granting or denying development permit applications in accordance with its provisions. Duties and responsibilities of the Planning Director shall include, but not be limited to:

a. Review all development permits to determine that the permit requirements of this code have been satisfied.

b. Review all development permits to determine that all necessary permits have been obtained from those Federal, State, or local governmental agencies from which prior approval is required.

c. Review all development permits to determine if the proposed development is located in the floodway. If located in the floodway, assure that the encroachment provisions of subsection (M)(1) of this section are met.

d. Make interpretations, where needed, as to the 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). A person contesting the location of the special flood hazard boundary shall be given an opportunity to seek a declaratory ruling or to appeal the interpretation as provided in BDC Chapter 4.1.

3. When base flood elevation data has not been provided on the FIRM, the Planning Director shall obtain, review, and reasonably utilize any base flood elevation and floodway data available from a Federal, State or other source, in order to administer this section.

a. Where base flood elevation data is provided through the Flood Insurance Study, FIRM, or required as in subsection (B)(3) of this section, verify and record the actual elevation (in relation to mean sea level) of the lowest floor (including basement) of all new or substantially improved structures, and whether or not the structure contains a basement.

b. For all new or substantially improved floodproofed structures, verify and record the actual elevation (in relation to mean sea level) to which the structure was floodproofed and maintain the floodproofing certifications required in subsection (G)(2) of this section.

C. Warning and Disclaimer of Liability. The degree of flood protection required by this section 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 code 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 code shall not create liability on the part of the City of Bend, any officer or employee thereof, or the Federal Insurance Administration, for any flood damages that result from reliance on this code or any administrative decision made hereunder.

1. Prior to any alteration or relocation of a watercourse, notice of the proposed alteration shall be given to affected, adjacent communities and appropriate State agencies such as the Department of Land Conservation and Development and the State Department of Water Resources. The Planning Director shall also submit evidence of such notification to the Federal Insurance Administration.

2. The applicant shall maintain the altered or relocated portion of said watercourse so that the flood carrying capacity is not diminished.

E. Permit for Use or Development in an FP Zone. No development shall occur in an FP Zone unless a permit has been received for the work. Except for improvement of an existing structure which is less than substantial, as determined by the City, no permit shall be issued unless the work will be reasonably safe from flooding, otherwise complies with this code, and all necessary State, Federal, and local permits will be obtained as a condition of approval on any permit in an FP Zone. The following information shall be submitted with the permit application:

1. The location of the property with reference to channel stations and flood profile elevations.

2. The existing topography and proposed grading plan for the property. Contour intervals shall not be more than one-foot for ground slopes up to five percent and, for areas immediately adjacent to a stream, two-foot for ground slopes between five and 10 percent, and five-foot for greater slopes.

3. The location of existing and proposed diking or revetments, if any.

4. Review of Building Permits. Where elevation data is not available either through the Flood Insurance Study, FIRM, or from another authoritative source, applications for building permits shall be reviewed to assure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. Failure to elevate at least two feet above the highest adjacent grade in these zones may result in higher flood insurance rates.

1. A building permit application for substantial improvement to an existing structure or for a new structure within an FP Zone shall contain the following data referenced to mean sea level:

a. The level of the lowest habitable floor and of any basement floor whether or not intended to be habitable. This information shall be submitted on FEMA Form 81-31.

b. The level to which the structure is to be floodproofed, if applicable.

2. A statement which notes whether the structure contains a basement.

3. The information required by this subsection shall be maintained in the files of the Building Department with the subject building permit.

a. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated a minimum of one foot 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:

i. 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.

ii. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.

iii. The bottom of all openings shall be no higher than one foot above grade.

2. Nonresidential Construction. New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall either have the lowest floor, including basement, elevated to the level of 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 subsection based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the City’s Building Official.

d. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subsection (G)(1)(b) of this section.

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).

3. Crawlspace Construction. 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:

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 can usually be addressed through the required openings stated in subsection (G)(3)(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. 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.

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.

4. Manufactured Homes. All manufactured homes to be placed or substantially improved within Zones AH or AE shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is a minimum of one foot above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of subsection (I)(2) of this section.

5. 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, be attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or

c. Meet the requirements of subsection (G)(3) of this section and the elevation and anchoring requirements for manufactured homes.

1. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.

2. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.

3. 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.

1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.

2. 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).

1. In addition to the terms of subsections (J) and (K) of this section, a subdivision or other land development, including all utility facilities, within an FP Zone shall be designed, located, and constructed to minimize flood damage, including special provisions for adequate drainage to reduce exposure to flood hazards.

2. A land development which will alter or relocate a watercourse shall be designed, constructed and maintained to retain the flood carrying capacity of the watercourse.

3. Where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated for subdivision proposals and other proposed developments which contain at least 50 lots or five acres (whichever is less).

1. All manufactured homes to be placed or substantially improved within Zones AH and AE shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is a minimum of one foot above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of subsection (I)(2) of this section.

2. The placement of a manufactured home in the floodway is prohibited.

1. A public utility or facility associated with a land development within a FP Zone shall be designed, located and constructed to minimize or eliminate flood damage and to avoid raising the water elevation in a regulatory floodway.

2. Any new or replacement water supply system shall be designed, located and constructed to minimize or eliminate infiltration of floodwaters into the system.

3. Any new or replacement sewerage system shall be designed, located and constructed to minimize or eliminate infiltration of floodwaters into the system and discharge from the system into the floodwaters.

M. Floodways. Located within areas of special flood hazard established in subsection (B)(1) of this section, Application of FP Zone, are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply:

1. Prohibit encroachments, including fill, new construction, substantial improvements, and other development unless certification by a registered professional civil engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.

2. If subsection (M)(1) of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of subsection (G) of this section, Regulations of Structures in an FP Zone.

N. Before 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 Zone 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.

O. Critical Facilities. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the Special Flood Hazard Area (SFHA) (100-year floodplain). Construction of new critical facilities shall be permissible within the SFHA if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor elevated three feet or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility should also be protected to the height utilized above. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters. Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities to the extent possible.

P. Technical Variances. A technical variance from the requirements of this section may be granted by the Hearings Body for new construction and for improvements to existing structures which could not otherwise be authorized, provided the construction or improvements are to be erected or installed on a parcel of land one-half acre or less in size, contiguous to or more or less surrounded by lots with existing structures constructed below the minimum floor elevation established for flood protection purposes. A parcel of land in excess of one-half acre in single ownership on the effective date of the ordinance codified in this code is not excluded from the granting of a technical variance, but the burden of proof required for issuing the variance increases as the size of the property under single ownership increases, and the variance shall be granted only if required to equalize circumstances, considering previously developed land adjacent to the parcel for which a variance is sought.

Q. Historic Variance. A variance for historic preservation may be granted for the reconstruction, rehabilitation or restoration of a structure listed on the National Register of Historic Places or the State Inventory of Historic Places.

R. Other Variances. All other variance applications shall be considered according to the terms of BDC Chapter 5.1.

1. Applicants for a variance shall include with their application the following information:

a. The location of the property with reference to channel station and flood profile elevation.

b. The existing topography and proposed grading plan for the property. Contour intervals shall not be more than one foot for ground slopes up to five percent and for areas immediately adjacent to a stream, two feet for ground slopes between five and 10 percent, and five feet for greater slopes.

c. The location of existing and proposed diking or revetments if any. [Ord. NS-2072, 2007; Ord. NS-2016, 2006; Ord. NS-1846, 2002; Ord. NS-1631, 1995; Ord. NS-1617, 1994; Ord. NS-1475, 1988; Ord. NS-1462, 1987]