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Title 17E
Chapter 17E.030
Section 17E.030.140
 

Title 17E Environmental Standards

Chapter 17E.030 Floodplain Management

Section 17E.030.140 Specific Standards

In all areas of special flood hazards where base flood elevation data has been provided as set forth in Section 17E.030.050(B), Basis for Establishing the Areas of Special Flood Hazard, or Section 17E.030.080(B), Use of Other Base Flood Data in “A” Zones, the following provisions are required:

  1. Residential Construction.
  1. New construction and substantial improvement of any residential structure in AE and other A Zones where BFE has been determined or can be reasonably obtained shall have the lowest floor, including basement, elevated two feet above the base flood elevation. Mechanical equipment and utilities shall be waterproof or elevated at least two foot above the BFE.
  1. New construction and substantial improvement of any residential structure in an Unnumbered A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the Highest Adjacent Grade.
  1. 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 shall either be certified by a registered professional engineer or architect or shall 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 must be provided.
  1. The bottom of all openings must be no higher than one foot above grade.
  1. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
  1. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of flood waters.
  1. Alternatively, a registered engineer or architect may design and certify engineered openings.
  1. Nonresidential Construction.

New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet the requirements of subsection 1 or 2, below:

    1. New construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall meet all of the following requirements:
    1. In AE, A1-30 zones, or other A zoned areas where the BFE has been determined or can be reasonably obtained, new construction and substantial improvement shall have the lowest floor, including basement, elevated two foot or more above the BFE, or elevated as required by ASCE 24, whichever is greater.
    1. Mechanical equipment and utilities shall be waterproofed or elevated least one foot above the BFE, or as required by ASCE 24, whichever is greater.
    1. If located in an Unnumbered A zone for which a BFE is not available and cannot be reasonably obtained, the structure shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the Highest Adjacent Grade.
    1. 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 a registered architect and must meet or exceed the following minimum criteria:
        1. Have 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;
        1. The bottom of all openings shall be no higher than one foot above grade; and
        1. Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwater.
    1. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of flood waters.
        1. Alternatively, a registered engineer or architect may design and certify engineered openings.
    1. If the requirements of subsection 1 are not met, then new construction and substantial improvement of any commercial, industrial, or other nonresidential structure shall meet all of the following requirements:
    1. Be dry floodproofed so that below two foot or more above the base flood level the structure is watertight with walls substantially impermeable to the passage of water or dry floodproofed to the elevation required by ASCE 24, whichever is greater;
    1. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;
    1. 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 Floodplain Administrator as set forth in SMC 17E.030.080;
    1. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in SMC 17E.030.140(A)(3).
    1. Applicants who are 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 floodproofed to the base flood level is rated as one foot below).
  1. Manufactured Homes.
    1. All manufactured homes to be placed or substantially improved on sites within the City’s Special Flood Hazard Areas (SFHAs) shall be elevated on a permanent foundation such that:
      1. the lowest floor of the manufactured home is elevated two feet above the Base Flood Elevation (BFE); and
      1. it be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement; and
      1. comply with SMC 17E.030.060(C) in completing an Elevation Certificate with the other necessary permits.
  1. Recreational Vehicles.

Recreational vehicles placed on sites are required to either:

  1. be on the site for fewer that one hundred and eighty consecutive days;
  1. be fully licensed and ready for highway use, on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions; or
  1. meet the requirements of subsection (C) of this section and the elevation and anchoring requirements for manufactured homes.
  1. Livestock Sanctuary Areas

Elevated areas for the for the purpose of creating a flood sanctuary for livestock are allowed on farm units where livestock is allowed. Livestock flood sanctuaries shall be sized appropriately for the expected number of livestock and be elevated two feet above the Base Flood Elevation (BFE). Proposals for livestock flood sanctuaries shall meet all procedural and substantive requirements of Chapter 17E.030.

  1. Enclosed Area Below the Lowest Floor.

If buildings or manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage.

Date Passed: Monday, October 25, 2021

Effective Date: Thursday, December 2, 2021

ORD C36118 Section 10