(A) In addition to the state permit and damage prevention requirements of § 94.06, all buildings located in the floodplain shall be protected from flood damage below the 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.
(2) Value of improvements equals or exceeds the market value by 50% or structural alterations made to an existing building that increase the floor area by more than 20%. Improvements shall be figured cumulatively during a ten-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 ten-year period. If substantially damaged, the entire structure must meet the flood protection standards of this section within 24 months of the date the damage occurred.
(4) Installing a manufactured home on a new site or a new manufactured home on an existing site.
(5) Installing a travel trailer or recreational vehicle on a site for more than 180 days per year.
(6) Repetitive loss to an existing building as defined in § 94.02.
(7) Construction or placement of a new building or alteration or addition to an existing building with the low floor below BFE; following a LOMR-F in accordance with the conditions outlined in § 94.09(E).
(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 land fill with the lowest floor including basement at or above the FPE in accordance with the following conditions:
(a) The lowest floor (including basement) shall be at or above the FPE.
(b) The fill shall be placed in layers no greater than six inches before compaction and should extend at least 20 feet beyond the foundation before sloping below the PTE in lieu of a geotechnical report.
(c) The fill shall be protected against erosion and scour during flooding by vegetative cover, riprap, or other structural measure.
(d) The fill shall be composed of rock or soil and not incorporated debris or refuse material.
(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, crawlspace, or other foundation that is permanently open to flood waters.
(b) All components located below the FPE shall be constructed of materials resistant to flood damage.
(c) The lowest floor and all electrical, heating, ventilating, plumbing, and air conditioning equipment shall be located at or above the FPE.
(d) If walls are used, all enclosed areas below the FPE shall provide for equalization of hydrostatic pressures by allowing the automatic entry and exit of floodwaters. At least two walls must have a minimum of one permanent opening that is below the BFE and no more than one foot above finished grade. The openings shall provide a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding below the BFE, or the design must be certified by a Registered P.E, as providing the equivalent performance in accordance with accepted standards of practice. Refer to FEMA TB 1, Openings in Foundation Walls and Walls of Enclosures, for additional guidance.
(e) 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. Water and sewer pipes, electrical and telephone lines, submersible pumps, and other service facilities may be located below the FPE provided they are waterproofed.
2. The area below the FPE shall be used solely for parking or building access and not later modified or occupied as habitable space.
3. 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 FPE provided that the following conditions and requirements of FEMA TB 11, Crawlspace Construction for Buildings Located in Special Flood Hazard Areas, which ever are more restrictive, 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) All enclosed areas below the FPE shall provide for equalization of hydrostatic pressures by allowing the automatic entry and exit of floodwaters. A minimum of one permanent opening shall be provided on at least two walls that is below the BFE and no more than one foot above finished grade. The openings shall provide a total net area of not less than one square inch for every one square foot of enclosed area subject to flooding below the BFE, or the design must be certified by a Registered P.E. as providing the equivalent performance in accordance with accepted standards of practice. Refer to FEMA TB 1, Openings in Foundation Walls and Walls of Enclosures, for additional guidance;
(c) The interior height of the crawlspace measured from the interior grade of the crawl to the top of the foundations wall must not exceed four feet at any point;
(d) 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;
(e) Portions of the building below the FPE must be constructed with materials resistant to flood damage; and
(f) Utility systems within the crawlspace must be elevated above the FPE.
(C) Non-residential buildings may be structurally dry floodproofed (in lieu of elevation) provided a licensed professional engineer or architect certifies that:
(1) Below the FPE 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 floodproofing for the purpose of this division.
(D) Manufactured homes or travel trailers to be permanently installed on site shall be:
(1) Elevated to or above the FPE in accordance with § 97.07(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 (210 1LCS 120/1) issued pursuant to 77 Ill. Adm. Code § 870.
(E) Travel trailers and recreational vehicles on site for more than 180 days per year shall meet the elevation requirements of § 94.07(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 vehicles having a total area not exceeding 400 square feet measured when measured at the largest horizontal projection.
(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 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 must either:
(a) Entirely be supported by jacks; or
(b) Have a hitch jack permanently mounted, have the tires touching the ground and be supported by block in a manner that will allow the block to be easily removed by use of the hitch jack.
(F) Detached accessory structures may be permitted provided the following conditions are met:
(1) The structure must be non-habitable.
(2) The structure must be used only for the parking and storage and cannot be modified later into another use.
(3) The structure must be located outside of the floodway or have the appropriate state and/or federal permits.
(4) The exterior and interior building components and elements (i.e., foundation, wall framing, exterior and interior finishes, flooring, etc.) below the BFE, must be built with flood-resistant materials in accordance § 94.07.
(5) All utilities, mechanical, and electrical must be elevated above the FPE.
(6) The structure must have at least one permanent opening on at least two walls not more than one foot above grade with one square inch of opening for every one square foot of floor area.
(7) The structure must be no more than one story in height and no more than 600 square feet in size.
(8) The structure shall be anchored to resist floatation, collapse, lateral movement. And overturning.
(9) All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, etc.) shall be stored above the FPE.
(10) The lowest floor elevation should be documented and the owner advised of the flood insurance implications.
(Ord. 2022-04, passed 7-7-2022) Penalty, see § 94.99