(a) Minimum Floodproofing Standards. In order to prevent excessive damage to buildings and structures, the following restrictions shall apply to all new construction and to construction of substantial improvements to existing structures occurring in the Flood Plain District.
(b) Basements and Lowest Floors. All new construction and substantial improvements of residential structures shall have the lowest floor, including basement, elevated to the base flood elevation. All new construction and substantial improvements of nonresidential structures shall have the lowest floor, including basement, elevated to base flood elevation; or together with attendant utility and sanitary facilities, shall be designed so that below the base flood elevation the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
(c) Enclosures Below a Structure; Lowest Floor. For all new construction and substantial improvements, fully enclosed areas below the lowest floor that are subject to flooding 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: 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 shall be provided. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
(d) Fill. If fill is used to raise the finished surface of the lowest floor to the base flood
elevation:
(1) Fill shall extend beyond a structure for a sufficient distance to provide acceptable access. For residential structures, fill shall extend laterally fifteen feet beyond the building line from all points. For nonresidential structures, fill shall be placed to provide access acceptable for intended use. At-grade access, with fill extending laterally fifteen feet beyond the building line, shall be provided to a minimum of twenty-five percent (25%) of the perimeter of a nonresidential structure.
(2) Fill shall consist of soil or rock materials only. Sanitary land fills shall not be permitted.
(3) Fill material shall be compacted to provide the necessary stability and resistance to erosion, scouring or settling.
(4) Fill slopes shall be no steeper than one vertical on two horizontal unless substantiating data justifying steeper slopes are submitted to and approved by the Chief Building Inspector.
(5) Fill shall be used only to the extent to which it does not adversely affect adjacent properties.
(e) Placement of Buildings, Structures and Manufactured Homes.
(1) All buildings and structures shall be constructed and placed on the lot so as to offer the minimum obstruction to the flow of water and shall be designed to have a minimum obstruction effect upon the flow and height of floodwater.
(2) The following shall not be placed or caused to be placed in the designated floodway: fences, except two-wire fences, other matter which may impede, retard or change the direction of the flow of water or that will catch or collect debris carried by such water, or that is placed where the natural flow of the stream or flood waters would carry the same downstream to the damage or detriment of either public or private property adjacent to the flood plain.
(3) Manufactured homes shall be elevated on compacted fill or on pilings so that the lowest floor of each manufactured home will be at the base flood elevation.
(4) Adequate surface drainage and access for a manufactured home hauler shall be provided.
(5) When manufactured homes are to be elevated on pilings, lots shall be large enough to permit steps, piles shall be placed in stable soil no more than ten feet apart, and reinforcement shall be provided for pilings more than six feet above ground level.
(6) Manufactured homes shall be placed on permanent foundations.
(f) Anchoring.
(1) All buildings and structures shall be firmly anchored in accordance with accepted engineering practices to prevent flotation, collapse and lateral movement, thus reducing the threat to life and property, and decreasing the possibility of the blockage of bridge openings and other restricted sections of the watercourse.
(2) All air ducts, large pipes and storage tanks located at or below the base flood elevation shall be firmly anchored to resist flotation.
(3) All manufactured homes shall be anchored to resist flotation, collapse or lateral movement by providing over-the-top and frame ties to ground anchors. Specifically:
A. Over-the-top ties shall be provided at each of the four corners of the manufactured home, with two additional ties per side at intermediate locations, and manufactured homes less than fifty feet long requiring one additional tie per side.
B. Frame ties shall be 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.
C. All components of the anchoring system shall be capable of carrying a force of 4,800 pounds.
D. Any additions to a manufactured home shall be similarly anchored.
(g) Storage. No new construction which stores materials that are buoyant, flammable, explosive or in times of flooding could be injurious to human, animal or plant life shall be stored below base flood elevation.
(Passed 7-24-00.)