Rules for building to resist flooding

(a) Natural terrain. The following shall be applicable to buildings on natural terrain: (1) Foundation design shall take into consideration the effects of soil saturation on the performance of the foundation; (2) The effects of floodwaters on slope stability and erosion shall be investigated; and (3) All utility service lines shall be designed and constructed as provided in the plumbing and electrical codes. (b) Building on stilts. Where a building is to be constructed so that the lowest floor is to be elevated above the base flood elevation, the building may be supported on columnar type members, such as columns, piers, and in certain cases, walls. Clear spacing of support members, measured perpendicular to the general direction of flood flow shall not be less than 8 feet apart at the closest point. The stilts shall, as far as practicable, be compact and free from unnecessary appendages that would tend to trap or restrict free passage of debris during a flood. Solid walls or walled-in columns are permissible if oriented with the longest dimension of the member parallel to the flow. Stilts shall be capable of resisting all applied loads as required by this code and all applicable flood-related loads as required herein. Bracing, where used to provide lateral stability, shall be of a type that causes the least obstruction to the flow and the least potential for trapping floating debris. Foundation supports for the stilts may be of any approved type capable of resisting all applied loads, such as spread footings, mats, piles, and similar types. In all cases, the effect of submergence of the soil and additional floodwater-related loads shall be recognized. The potential of surface scour around the stilts shall be recognized and protective measures provided, as required. (c) Building on fill. (1) Except in districts where fill is specifically prohibited as structural support for buildings by Chapter 21A , buildings may be constructed on fill material. (2) The fill shall not adversely affect the capacity of the floodway or any tributary or any other drainage facility or system, and shall be performed in accordance with Chapter 14 . ; Sec. 16-5.4, R.O. 1978 (1987 Supp. to 1983 Ed.))