(a) In addition to the state permit and damage prevention requirements of Section 1460.06, all buildings located in the floodplain shall be protected from flood damage below the flood protection elevation (FPE). This building protection requirement applies to the following situations:
(1) Construction or placement of a new building or alteration or addition to an existing building valued at more than one thousand dollars ($1,000) or seventy (70) square feet;
(2) Substantial improvements or structural alterations made to an existing building that increase the floor area by more than twenty percent (20%) or equal or exceed fifty percent (50%) of the market value. This alteration shall be figured cumulatively during a 10-year period. If substantially improved, the existing structure and the addition must meet the flood protection standards of this section;
(3) Repairs made to a substantially damaged building. These repairs shall be figured cumulatively during a 10-year period. If substantially damaged, the entire structure must meet the flood protection standards of this section within twenty-four (24) months of the date the damage occurred;
(4) Installation of a manufactured home on a new site or a new manufactured home on an existing site. This section does not apply to returning a manufactured home to the same site it lawfully occupied before it was removed to avoid flood damage;
(5) Installation of a travel trailer on a site for more than one hundred eighty (180) days per year; and
(6) Repetitive loss to an existing building as defined in Section 1460.02.
(b) Residential or non-residential buildings can meet the building protection requirements by one of the following methods:
(1) The building may be constructed on permanent fill in accordance with the following:
A. The lowest floor (including basement) shall be at or above the flood protection elevation;
B. The fill shall be placed in layers no greater than six inches before compaction and shall extend at least ten (10) feet beyond the foundation before sloping below the flood protection elevation;
C. The fill shall be protected against erosion and scour during flooding by vegetative cover, rip rap or other structural measure;
D. The fill shall be composed of rock or soil and not incorporated debris or refuse material; and
E. The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties and when necessary stormwater management techniques such as swales or basins shall be incorporated.
(2) The building may be elevated on solid walls in accordance with the following:
A. The building or improvements shall be elevated on stilts, piles, walls, or other foundation that is permanently open to flood waters;
B. The lowest floor and all electrical, heating, ventilating, plumbing, and air conditioning equipment and utility meters shall be located at or above the flood protection elevation;
C. If walls are used, all enclosed areas below the FPE shall address hydrostatic pressures by allowing the automatic entry and exit of flood waters. Designs must either be certified by a licensed professional engineer or by having a minimum of one (1) permanent opening on each wall no more than one (1) foot above grade with a minimum of two (2) openings. The openings shall provide a total net area of not less than one (1) square inch for every one (1) square foot of enclosed area subject to flooding below the BFE;
D. The foundation and supporting members shall be anchored, designed, and certified so as to minimize exposure to hydrodynamic forces such as current, waves, ice and floating debris;
1. All structural components below the FPE shall be constructed of materials resistant to flood damage; and
2. Water and sewer pipes, electrical and telephone lines, submersible pumps, and other service facilities may be located below the FPE provided they are waterproofed; and
3. The area below the FPE shall be used solely for parking or building access and not later modified or occupied as habitable space; or
4. In lieu of the above criteria, the design methods to comply with these requirements may be certified by a licensed professional engineer or architect.
(3) The building may be constructed with a crawlspace located below the flood protection elevation provided that the following conditions are met:
A. The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
B. Any enclosed area below the flood protection elevation shall have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. A minimum of one opening on each wall having a total net area of not less than one (1) square inch per one (1) square foot of enclosed area. The openings shall be no more than one (1) foot above grade;
C. The interior grade of the crawlspace below the flood protection elevation must not be more than two (2) feet below the lowest adjacent exterior grade;
D. The interior height of the crawlspace measured from the interior grade of the crawlspace to the top of the foundation wall must not exceed four (4) feet at any point;
E. An adequate drainage system must be installed to remove floodwaters from the interior area of the crawlspace within a reasonable period of time after a flood event;
F. Portions of the building below the FPE must be constructed with materials resistant to flood damage; and
G. Utility systems within the crawlspace must be elevated above the flood protection elevation.
(c) Non-residential buildings may be structurally dry flood proofed (in lieu of elevation) provided a licensed professional engineer or architect certifies that:
(1) Below the flood protection elevation the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood.
(2) The building design accounts for flood velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the effects of buoyancy, and the impact from debris and ice.
(3) Floodproofing measures will be incorporated into the building design and operable without human intervention and without an outside source of electricity.
(4) Levees, berms, floodwalls and similar works are not considered flood proofing for the purpose of this subsection.
(d) Manufactured homes and travel trailers to be permanently installed on site shall be:
(1) Elevated at or above the FPE in accordance with Section 1460.07(b); and
(2) 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 IL Adm. Code § 870.
(e) Travel trailers and recreational vehicles on site for more than one hundred eighty (180) days per year shall meet the elevation requirements of 1460.07(d) unless the following conditions are met:
(1) The vehicle must be either self-propelled or towable by a light duty truck;
(2) The hitch must remain on the vehicle at all times;
(3) The vehicle must not be attached to external structures such as decks and porches;
(4) The vehicle must be designed solely for recreation, camping, travel or seasonal use rather than as a permanent dwelling;
(5) The vehicle's largest horizontal projections must be no larger than four hundred (400) square feet;
(6) The vehicle's wheels must remain on axles and inflated;
(7) Air conditioning units must be attached to the frame so as to be safe for movement out of the floodplain;
(8) Propane tanks as well as electrical and sewage connections must be quick-disconnect;
(9) The vehicle must be licensed and titled as a recreational vehicle or park model; and
(10) The vehicle must be either:
A. be entirely supported by jacks, or
B. have a hitch jack permanently mounted, have the tires touching the ground, and be supported by blocks in a manner that will allow the blocks to be easily removed by use of the hitch jack.
(g) Garages, sheds or other minor accessory structures constructed ancillary to an existing residential use may be permitted provided the following conditions are met:
(1) The garage or shed must be non-habitable;
(2) The garage or shed must be used only for the storage of vehicles and tools and cannot be modified later into another use;
(3) The garage or shed must be located outside of the floodway or have the appropriate state and/or federal permits:
(4) The garage or shed must be on a single family lot and be accessory to an existing principal structure on the same lot;
(5) Below the BFE, the garage or shed must be built of materials not susceptible to flood damage;
(6) All utilities, plumbing, heating, air conditioning and electrical must be elevated above the FPE;
(7) The garage or shed must have at least one permanent opening on each wall no more than one (1) foot above grade with one (1) square inch of opening for every one (1) square foot of floor area;
(8) The garage or shed must be less than fifteen thousand dollars ($15,000) in market value or replacement cost (whichever is greater) and less than five hundred seventy-six (576) square feet (24' x 24');
(9) The structure shall be anchored to resist flotation and overturning;
(10) All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, etc.) shall be stored above the FPE; and
(11) The lowest floor elevation shall be documented and the owner advised of the flood insurance implications.
(Ord. 2005-59. Passed 11-21-05; Ord. 2011-07. Passed 2-7-11.)