Spokane Municipal Code

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, including those related to manufactured homes, shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads including the buoyancy.

2. 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 or frame ties 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;

2. 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;

3. all components at the anchoring system are capable of carrying a force of four thousand eight hundred pounds; and

4. any additions to the manufactured home are similarly anchored.

3. The guidebook “Manufactured Home Installation in Flood Hazard Areas, FEMA-85 is adopted by reference for further manufactured home anchoring techniques.

2. Construction Materials and Methods.

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.

3. Storage of Materials and Equipment

1. The storage or processing of materials that could be injurious to human, animal, or plant life if released due to damage from flooding is prohibited in special flood hazard areas.

2. Storage of other material or equipment may be allowed if not subject to damage by floods and if firmly anchored to prevent flotation, or if readily removable from the area within the time available after flood warning.

4. Utilities.

1. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.

2. Any proposed water well shall be located on high ground that is not in the floodway (WAC 173-160-171).

3. 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.

4. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

5. Development and Subdivision Proposals.

All development, including subdivisions, shall:

1. Be consistent with the need to minimize flood damage;

2. Have public utilities and facilities, such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage;

3. Have adequate drainage provided to reduce exposure to flood damage; and

4. Where subdivision proposals and other proposed developments contain greater than 50 lots or 5 acres (whichever is the lesser) base flood elevation data shall be included as part of the application, and prepared by an engineer licensed in the State of Washington.

6. Minimum Requirements.

All development or which specific provisions are not specified in the Spokane Municipal Code or the state building codes, and adopted amendments, shall:

1. Be located and constructed to minimize flood damage;

2. Meet the encroachment limitations of this ordinance if located in a regulatory floodway;

3. Be anchored to prevent flotation, collapse, or lateral movement resulting from hydrostatic loads, including the effects of buoyancy, during conditions of the design flood;

4. Be constructed of flood damage-resistant materials;

5. Meet the flood opening requirements of SMC 17E.030.140(A)(3), and

6. Have mechanical, plumbing, and electrical systems above the design flood elevation or meet the requirements of ASCE 24, except that minimum electric service required to address life safety and electric code requirements is permitted below the design flood elevation provided it conforms to the provisions of the electrical part of building code for wet locations

Date Passed: Monday, October 25, 2021

Effective Date: Thursday, December 2, 2021

ORD C36118 Section 9