(A) All buildings located within a 100-year flood plain also known as a SFHA, shall be protected from flood damage below the flood protection elevation. However, existing buildings located within a regulatory floodway shall also meet the more restrictive appropriate use standards included in § 153.58. This building protection criteria applies to the following situations:
(1) Construction or placement of a new building;
(2) A structural alteration to an existing building that either increases the first floor area by more than 20% or the building's market value by more than 50%;
(3) Installing a manufactured home on a new site or a new manufactured home on an existing site. This building protection requirement does not apply to returning a mobile home to the same site it lawfully occupied before it was removed to avoid flood damage; and
(4) Installing a travel trailer on a site for more than 180 days.
This building protection requirement may be met by one of the following methods.
(B) A residential or nonresidential building, when allowed, may be constructed on permanent land fill in accordance with the following:
(1) The lowest floor (including basement) shall be at or above the flood protection elevation.
(2) The fill shall be placed in layers no greater than one foot deep before compaction and should extend at least ten feet beyond the foundation of the building before sloping below the flood protection elevation. The top of the fill shall be above the flood protection elevation. However, the ten-foot minimum may be waived if a structural engineer certifies an alternative method to protect the building from damages due to hydrostatic pressures. The fill shall be protected against erosion and scour. The fill shall not adversely effect the flow or surface drainage from or onto neighboring properties.
(C) A residential or nonresidential building may be elevated in accordance with the following:
(1) The building or improvements shall be elevated on crawl space, stilts, piles, walls, or other foundation that is permanently open to flood waters and not subject to damage by hydrostatic pressures of the base flood or 100-year frequency flood. The permanent openings shall be no more than one foot above grade, and consist of a minimum of two openings. The openings must have a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding below the base flood elevation.
(2) The foundation and supporting members shall be anchored and aligned in relation to flood flows and adjoining structures so as to minimize exposure to known hydrodynamic forces such as current, waves, ice and floating debris.
(3) All areas below the flood protection elevation shall be constructed of materials resistant to flood damage. The lowest floor (including basement) and all electrical, heating, ventilating, plumbing and air conditioning equipment and utility meters shall be located at or above the flood protection elevation. Water and sewer pipes, electrical and telephone lines, submersible pumps, and other waterproofed service facilities may be located below the flood protection elevation.
(4) No area below the flood protection elevation shall be used for storage of items or materials.
(5) Manufactured homes and travel trailers to be installed on a site for more than 180 days, shall be elevated to or above the flood protection elevation; and, shall be anchored to resist flotation, collapse, or lateral movement by being tied down in accordance with the rules and regulations for the Illinois Mobile Home Tie-Down Act issued pursuant to 77 Ill. Adm. Code 870.
(D) (1) Only a nonresidential building may be structurally dry floodproofed (in lieu of elevation) provided that a registered professional engineer shall certify that the building has been structurally dry floodproofed below the flood protection elevation, the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood or 100-year frequency flood. The building design shall take into account flood velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the effects of buoyancy, and impacts from debris or ice. Floodproofing measures shall be operable without human intervention and without an outside source of electricity (levees, berms, floodwalls and similar works are not considered floodproofing for the purpose of this division).
(2) Tool sheds and detached garages on an existing single-family platted lot, may be constructed with the lowest floor below the flood protection elevation in accordance with the following:
(a) The building is not used for human habitation.
(b) All areas below the base flood or 100-year frequency flood elevation shall be constructed with waterproof material. Structures located in a regulatory floodway shall be constructed and placed on a building site so as not to block the flow of flood waters and shall also meet the appropriate use criteria of §§ 153.55 through 153.63. In addition, all other requirements of §§ 153.45 through 153.48, 153.55 through 153.63 and 153.70 through 153.76 must be met.
(c) The structure shall be anchored to prevent flotation.
(d) Service facilities such as electrical and heating equipment shall be elevated or floodproofed to the flood protection elevation.
(e) The building shall be valued at less than $5,000 and be less than 500 square feet in floor size.
(f) The building shall be used only for the storage of vehicles or tools and may not contain other rooms, workshops, greenhouses or similar uses.
(E) Nonconforming structures located in a regulatory floodway may remain in use, but may not be enlarged, replaced or structurally altered. A nonconforming structure damaged by flood, fire, wind or other natural or man-made disaster may be restored unless the damage exceeds 50% of its market value before it was damaged, in which case it shall conform to this chapter.
(Ord. 553, passed 10-2-89; Am. Ord. 703, passed 4-6-92; Am. Ord. 789, passed 1-24-94)