(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 flood protection elevation (FPE).
(2) New and replacement water supply systems, wells, sanitary sewer lines and onsite waste disposal systems may be permitted, providing all manholes or other above ground openings located below the FPE are watertight.
(B) Carrying capacity and notifications.
(1) For all projects involving channel modification, fill or stream maintenance (including levees), the flood carrying capacity of the watercourse shall be maintained.
(2) In addition, the village shall notify adjacent communities in writing 30 days prior to the issuance of a permit for the alteration or relocation of the watercourse.
(C) Protecting buildings.
(1) All buildings located within a 100-year floodplain also known as a SFHA, and all buildings located outside the 100-year floodplain but within the 500-year floodplain, shall be protected from flood damage below the flood protection elevation. This building protection criteria applies to the following situations:
(a) Construction or placement of a new building;
(b) A structural alteration to an existing building that either increases its first floor area by more than 20% or the building’s market value by more than 50%. This alteration shall be figured cumulatively beginning with any alteration which has taken place subsequent to April 1, 1990;
(c) Installing a manufactured home on a new site or a new manufactured home on an existing site. These building protection requirements do not apply to returning a mobile home to the same site it lawfully occupied before it was removed to avoid flood damage; and
(d) Installing a travel trailer on a site for more than 180 days. These building protection requirements may be met by one of the following methods:
(2) A residential or nonresidential building, when allowed, may be constructed on permanent land fill in accordance with the following:
(a) The lowest floor (including basement) shall be at or above the flood protection elevation;
(b) Fill requirements:
1. 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;
2. 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;
3. The fill shall be protected against erosion and scour; and
4. The fill shall not adversely affect the flow or surface drainage from or on to neighboring properties.
(3) A residential or nonresidential building may be elevated in accordance with the following:
(a) 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 existing grade and shall 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;
(b) 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;
(c) All areas below the flood protection elevation shall be constructed of materials resistant to flood damage:
1. The lowest floor (including basement) and all electrical, heating, ventilating, plumbing and other waterproofed service facilities may be located below the flood protection elevation; and
2. Water and sewer pipes, electrical and telephone lines, submersible pumps, and other waterproofed service facilities may be located below the flood protection elevation.
(d) The areas below the flood protection elevation may only be used for the parking of vehicles, building access or storage in an area other than a basement;
(e) 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 and Tie-Down Act issued pursuant to 77 Ill. Adm. Code Part 870. In addition, all manufactured homes shall meet the following elevation requirements:
1. In the case of manufactured homes placed on substantially improved parcels outside of a manufactured home park or subdivision in a new manufactured home park or subdivision, in an expansion to an existing manufactured home park or subdivision, or in an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage from a flood, the top of the lowest floor shall be raised to or above the flood protection elevation; and
2. In the case of manufactured homes placed or substantially improved in an existing manufactured home park or subdivision, the manufactured home shall be elevated so that either the top of the lowest floor is above the base flood elevation or the chassis is at least 36 inches in height above grade and supported by reinforced piers or other foundations of equivalent strength, whichever is less.
(f) Recreational vehicles or travel trailers shall be required to meet the elevation and anchoring requirements of division (C)(3)(e) above unless:
1. They are on site for fewer than 180 consecutive days; and
2. They are fully licensed and ready for highway use. A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect type utility and service devices, and has no permanently attached additions.
(4) Only a nonresidential building may be structurally dry flood proofed (in lieu of elevation) provided that:
(a) A registered professional engineer shall certify that the building has been structurally dry flood proofed below the flood protection elevation, the structure and attendant utility facilities are watertight and are capable of resisting the effects of the base flood or 100-year frequency flood;
(b) 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; and
(c) Flood proofing measures shall be operable without human intervention and without an outside source of electricity. (Levees, berms, floodwalls and similar works are not considered flood proofing measures for the purposes of this division).
(5) 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 criteria:
(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 designated 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 § 154.08. In addition, all other requirements of §§ 154.07, 154.08 and 154.09 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 flood proofed to the flood protection elevation;
(e) The building shall be valued at less than $7,500 and shall 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; and
(g) The building shall meet the permanent opening criteria of division (C)(3)(a) above.
(6) Existing buildings located within a designated floodway shall also meet the more restrictive appropriate use standards included in § 154.08. Nonconforming structures located in a designated floodway may remain in use and may only be enlarged, replaced or structurally altered in accordance with § 154.08(B). A nonconforming structure damaged by flood, fire, wind or other natural or human-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.
(7) Buildings constructed on property removed from the floodplain by filling shall have their lowest habitable floors (including basements) set at the flood protection elevation. If the builder chooses to accept the higher risk of constructing habitable floors below the flood protection elevation, the lowest floor may be as much as five feet below the base flood elevation, provided the builder demonstrates compliance with the simplified approach identified in the Federal Emergency Management Agency’s Technical Bulletin 10-01.
(D) For public flood control projects, the floodplain management standards will be considered met if the applicant can demonstrate to IDNR/OWR and the village that each of the following conditions are met:
(1) Demonstrate by hydraulic and hydrologic modeling that the proposed project will not singularly or cumulatively result in increased flood heights outside the project site or demonstrate that any increases will be contained in easements for all flood events up to and including the base flood event;
(2) Demonstrate that the project will be operated and maintained by a public agency; and
(3) Demonstrate that the project will reduce flood damage to an existing building or structure.
(Ord. 765, passed 10-20-2004)