In addition to the requirements found in Sections 7-1-7, 7-1-8, and 7-1-9 of this Chapter for development in flood fringes, regulatory floodways, and SFHA or flood plains where no floodways have been identified (Zones A, AO, AH, AE, A1-A30, A99, VO, V-30, VE V, M, or E), the following requirements shall be met:
A. Public Health Standards:
1. No developments in the SFHA shall include locating or storing chemicals, explosives, buoyant materials, animal wastes, fertilizers, flammable liquids, pollutants, or other hazardous or toxic materials below the FPE.
2. New and replacement water supply systems, wells, sanitary sewer lines and on-site waste disposal systems may be permitted providing all manholes or other aboveground openings located below the FPE are watertight.
B. Carrying Capacity And Notification. For all projects involving channel modification, fill, or stream maintenance (including levees), the flood carrying capacity of the watercourse shall be maintained. In addition, the City shall notify adjacent communities in writing thirty (30) days prior to the issuance of a permit for the alteration or relocation of the watercourse.
C. Protecting Buildings: 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 Section 7-1-8. 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 twenty percent (20%) or the building's market value by more than fifty percent (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 one hundred eighty (180) days.
This building protection requirement may be met by one of the following methods.
a. 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 (1') deep before compaction and should extend at least ten feet (10') 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 (10') 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 affect the flow or surface drainage from or onto neighboring properties.
b. 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 (1') above grade, and consists of a minimum of two (2) 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 one hundred eighty (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 Illinois Administrative Code 870.
c. Only a nonresidential building may be structurally 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, berm, floodwalls and similar works are not considered floodproofing for the purpose of this subsection).
d. 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 manmade disaster may be restored unless the damage exceeds fifty percent (50%) of its market value before it was damaged, in which case it shall conform to this Chapter. (Ord. 0-90-37, 8-20-1990)