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Title 17E
Chapter 17E.030
Section 17E.030.130
 

Title 17E Environmental Standards

Chapter 17E.030 Floodplain Management

Section 17E.030.130 General Standards

In all areas of special flood hazards, the following standards, in addition to those imposed by other existing regulations are required:

  1. Anchoring.
    1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.
    1. All manufactured homes shall 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:
      1. use of over-the-top is provided at each of the four corners of the manufactured home, with two additional ties per site at intermediate locations, with manufactured homes less than fifty feet long requiring one additional tie per side;
      1. frame ties is provided at each corner of the home with five additional ties per side at intermediate points, with manufactured homes less than fifty feet long requiring four additional ties per side;
      1. all components at the anchoring system are capable of carrying a force of four thousand eight hundred pounds; and
      1. any additions to the manufactured home are similarly anchored.
    1. The guidebook “Manufactured Home Installation in Flood Hazard Areas, FEMA-85, 9/85” is adopted by reference for further manufactured home anchoring techniques.
  1. AO Zone Drainage.

Adequate drainage paths are required around structures on slopes to guide floodwaters around and away from proposed structures.

  1. Construction Materials and Methods.
    1. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
    1. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
    1. 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. Utilities.
    1. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.
    1. Any proposed water well shall be located on high ground that is not in the floodway (WAC 173-160-171).
    1. 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.
    1. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
  1. Subdivision Proposals.

All subdivision proposals shall:

    1. be consistent with this chapter;
    1. be consistent with the need to minimize flood damage;
    1. have public utilities and facilities, such as sewer, gas, electrical and water systems located and constructed to minimize or eliminate flood damage;
    1. have adequate drainage provided to reduce exposure to flood damage; and
    1. be generated by an engineer hired by the applicant for subdivision proposals and other proposed developments which contain at least fifty lots or five acres, whichever is less; where base flood elevation data has not been provided or is not available from another source.
  1. Review of Building Permits.

Where elevation data is not available either through the flood insurance study or from another authoritative source, applications for building and land use 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, et cetera, where available. Failure to elevate at least two feet above highest adjacent grade in these zones may result in higher insurance rates. The applicant will provide studies and information as necessary for review.

Date Passed: Monday, November 24, 2008

Effective Date: Saturday, January 10, 2009

ORD C34352 Section 2