This chapter adopts the procedures and performance standards required for Power County's participation in the National Flood Insurance Program. (Ord. 2019-01, 1-14-2019)

The Floodplain Overlay District (FOD) includes and is coterminous with all flood-prone areas identified by the U.S. Geological Survey and all special flood hazard areas identified by the Federal Emergency Management Agency (FEMA). (Ord. 2019-01, 1-14-2019)

   A.   Development Defined: In the FOD, "development" shall include any activity that may potentially affect flood flows. This includes all land disturbance, including grading and the construction of fills for any purpose, as well as all building construction, and is more comprehensive than the definition of development used in other portions of the County.

   B.   Warning; Disclaimer Of Liability: All applicants for permits in the FOD shall sign an acknowledgement stating:

   C.   Additional Application Requirements: All applications for permits in the FOD shall be accompanied by the following information:

      1.   Elevation of the lowest floor of all proposed buildings.

      2.   Elevation to which any existing or proposed building has been or will be floodproofed.

      3.   For all buildings other than single-family dwellings: certification by an engineer or architect that the floodproofing methods used comply with these performance standards.

      4.   Where alteration of any watercourse or wetlands is proposed: a description of the extent to which the watercourse or wetlands will be altered or relocated as a result of the proposed development and proof that all State or Federal permits required for that alteration have been approved.

      5.   The developer shall provide base flood elevation data for all subdivisions or special permit uses that include fifty (50) or more lots or dwelling units or one or more acres.

   D.   Duties Of Administrator: The Administrator shall serve as the local Floodplain Ordinance Administrator and perform the duties listed below:

      1.   Determine that all required State and/or Federal permits have been obtained before reviewing any application for a permit in the FOD.

      2.   Where base flood elevation data are not provided by FEMA: obtain and reasonably utilize any base flood elevation and floodway data available from State, Federal, or other sources as a basis for the administration of these performance standards.

      3.   Maintain a record of the actual elevation of the lowest floor of new or substantially improved buildings, and whether or not the building contains a basement.

      4.   Maintain a record of the floodproofing certifications required by subsection C3 of this section.

      5.   Notify the Idaho Department of Water Resources prior to the alteration or relocation of a watercourse, and submit evidence of that notification to the Federal Insurance Administration.

      6.   Maintain records of appeal actions and report all variances allowed to the Federal Insurance Administration. (Ord. 2019-01, 1-14-2019)

   A.   Anchoring: New construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement. Manufactured homes shall be anchored to prevent flotation, collapse, or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, the use of over-the-top or frame ties to ground anchors.

   B.   Construction Materials And Methods:

      1.   New construction and substantial improvements shall be constructed with materials and utility equipment that is resistant to flood damage, and using methods and practices that minimize flood damage.

      2.   All electrical, heating, ventilation, plumbing, and air conditioning equipment, and other service facilities shall be designed, or elevated, or located, so as to prevent water from entering or accumulating within their components during flooding.

   C.   Utilities And Solid Waste:

      1.   New and replacement potable water systems shall be designed to eliminate infiltration of flood waters into the system.

      2.   New and replacement sewage disposal systems shall be designed to eliminate infiltration of flood waters into the system and discharge from the system into flood waters.

      3.   Solid waste handling and storage facilities shall not be located in the FOD.

   D.   Hazardous Substances: Storage and handling of hazardous substances in the FOD is prohibited.

   E.   Site Planning: Design and construction of all subdivisions and uses for which a special use permit is required shall minimize flood damage. Utilities shall be located and designed to minimize flood damage, and the site shall be graded and drained to guide flood waters around and away from existing and/or proposed buildings.

   F.   Residential Development: Subsections F1 and F2 of this section apply only where base flood elevations have been established by FEMA.

      1.   Construction or substantial improvement of any dwelling shall result in the lowest floor being elevated to or above base flood elevation.

      2.   Fully enclosed areas below the lowest floor are prohibited, except where designed to automatically equalize hydrostatic forces on exterior walls by allowing for entry and exit of flood waters. Designs for meeting this requirement shall either be certified by an engineer or architect, or meet the following minimum standards:

         a.   A minimum of two (2) 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;

         b.   The bottom of such openings shall be no higher than one foot (1') above grade; and

         c.   Such openings may be equipped with screens, louvers, or other coverings or devices, provided they permit automatic entry and exit of flood waters.

      3.   Where base flood elevation data is not available through the Flood Insurance Study or from another authoritative source, applications must be reviewed to assure that the proposed construction will be reasonably safe from flooding. This determination of reasonableness shall be based on evidence submitted with the application by the developer, including historical flood records, including photographs of past flood events and similar documentation. The minimum elevation above grade in such cases shall be two feet (2').

   G.   Nonresidential Development: Construction or substantial improvement of any nonresidential building shall result in the lowest floor being elevated to or above base flood elevation or, together with the attendant utility and sanitary facilities, shall:

      1.   Be floodproofed so that below base flood level, the building is watertight, with walls substantially impermeable to the passage of water;

      2.   Be designed and constructed to resist hydrostatic and hydrodynamic loads and the effects of buoyancy;

      3.   Present a certification from an engineer or architect that the design and methods of construction comply with accepted standards of practice for meeting the performance standards of this title; and

      4.   Meet the performance standard of subsection F2 of this section for enclosed spaces below the lowest floor.

      5.   Developers floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot (1') below the floodproofed level.

   H.   Manufactured Homes: Manufactured homes that are placed, replaced, or substantially improved within the FOD shall be elevated on and securely anchored to a permanent foundation, so that the lowest floor is at or above base flood elevation, where a base flood elevation has been established or at least two feet (2') above grade where no base flood elevation has been established.

   I.   Floodways: The floodway is the channel of a river or other watercourse and any adjacent land area that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one foot (1'). The floodway is a hazardous area due to the velocity of flood waters which carry debris and potential projectiles, and due to the high erosion potential. Encroachments into the floodway, including fill, new construction, substantial improvements, and other development is prohibited, unless an engineer or architect certifies that the encroachment will not result in any increase in the flood level during the base flood discharge.

   J.   Maintenance Of Flood Capacity: Continuing maintenance to prevent the reduction of flood carrying capacity in altered or relocated watercourses shall be required.

   K.   Areas Of Shallow Flooding (AO Zones): An area of shallow flooding is an AO or AH Zone on the Flood Insurance Rate Map (FIRM). In these areas, base flood depth ranges from one foot (1') to three feet (3'), a clearly defined channel does not exist, the path of flooding is unpredictable and indeterminate, and velocity flow may be evident.

      1.   Construction and substantial improvement of dwellings in AO Zones shall result in the lowest floor being elevated above the highest adjacent grade of the building site to or above the depth number specified on the FIRM or to at least two feet (2'), where no depth number is specified.

      2.   All new construction and substantial improvement of nonresidential buildings in AO Zones shall:

         a.   Be graded and drained to guide flood waters around and away from existing and/or proposed buildings; and

         b.   Have the lowest floor elevated above the highest adjacent grade of the building site to or above the depth number specified on the FIRM or, where no depth number is specified, to at least two feet (2') above the highest adjacent grade; or

         c.   Together with its attendant utility and sanitary facilities, be floodproofed so that any space below that level is watertight, with substantially impermeable walls and structural components capable of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. Compliance shall be certified by an engineer or architect. (Ord. 2019-01, 1-14-2019)

   A.   Additional Finding For Variances: The approval of any variance in the FOD shall be based on all findings required by subsection 10-2-3B4 of this title, and the additional finding that approval of the variance will not result in increased flood levels, a threat to public safety, or extraordinary public expense.

   B.   Notice Of Variance: Where a variance of the requirements of this chapter is approved, the Administrator's notice of the decision shall state that the County is not liable for any flood damages that result from the variance. Where a variance of the elevation requirements of this chapter is approved, the Administrator shall also notify the developer that the cost of flood insurance will be commensurate with the increased risk resulting from the reduced lowest floor elevation. (Ord. 2019-01, 1-14-2019)