(A) In addition to the state permit damage prevention requirements of § 151.25 of this code, all buildings and building related development located in the floodplain shall be protected from flood damage below the flood protection elevation. 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 and/or building related development valued at more than $1,000 or 70 square feet.
(2) Substantial improvements or structural alterations made to an existing building and/or building related development that increase the floor area by more than 20% or equal or exceed the market value by 50%. Alteration shall be figured cumulatively subsequent to the adoption of this chapter. 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 and/or building related development. These repairs shall be figured cumulatively subsequent to the adoption of this chapter. 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. (The building protection requirements do not apply to returning a manufactured home to the same site it lawfully occupied before it was removed to avoid flood damage).
(5) Installing a travel trailer and recreational vehicle on a site for more than 180 days per year.
(6) Repetitive loss to an existing building and/or building related development as defined in § 151.02. If repetitive loss occurs the entire structure must meet the flood protection standards of this section within 24 months of the date the damage occurred.
(B) Residential or non-residential buildings can meet the building protection requirements of division (A) above by one of the following methods.
(1) The building may be constructed on permanent clean fill utilizing compacted earthen materials 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 one foot before compaction and should extend at least ten 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, riprap or other structural measure;
(d) The fill shall be composed of rock or soil and not incorporate any debris or refuse materials;
(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; and
(f) Footings shall be placed on undisturbed earth or a licensed professional engineer shall certify in writing that the building shall be reasonably safe from flooding.
(2) The building or building related development may be elevated in accordance with the following:
(a) The building or improvements and/or building related development shall be elevated on stilts, piles, walls or other foundation that is permanently open to floodwaters;
(b) The lowest floor and all electrical, heating, ventilating, plumbing, and air conditioning equipment and utility meters on the property shall be located at or above the flood protection elevation except that the water and sewer pipes, electrical lines, telephone lines, submersible pumps and other service facilities may be located below the flood protection elevation provided they are waterproofed;
(c) The foundation and supporting members shall be anchored and aligned in relation to flood flows and adjoining structures so as to minimize exposure to hydrodynamic forces such as current, waves, ice and floating debris;
(d) If walls are used to elevate the building and/or building related development, all enclosed areas below the flood protection elevation shall address hydrostatic pressures by allowing the automatic entry and exit of floodwaters. Designs must either be certified by a licensed professional engineer or by having a minimum of one permanent opening on each wall no more than one foot above grade with a minimum of two openings per enclosed area. The openings shall provide a total net area of not less than one square inch of opening for every one square foot of enclosed area subject to flooding below the base flood elevation. Insect screens may cover flood openings provided that the insect screen does not unduly impede the entry and exit of floodwaters;
(e) The finished interior grade shall not be less than the finished exterior grade;
(f) All structural components below the flood protection elevation shall be constructed of materials resistant to flood damage;
(g) The area below the flood protection elevation shall be used solely for parking or building access and not later modified or occupied as habitable space;
(h) Footings shall be placed on undisturbed earth or a licensed professional engineer shall certify in writing that the building shall be reasonable safe from flooding; and
(i) In lieu of the above criteria, the design methods to comply with these requirements may be certified by a licensed professional engineer or licensed architect.
(3) The building and/or building related development may be constructed with a crawlspace
located below the flood protection elevation provided that the following conditions are met:
(a) The building and/or building related development 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. There shall be a minimum of one opening on each wall having a total net area of not less than one square inch of open area per one square foot of enclosed area subject to flooding below the base flood elevation. The openings shall be no more than one foot above grade with a minimum of two openings per enclosed area. Insect screens may cover flood openings provided that the insect screen does not unduly impede the entry and exit of floodwaters;
(c) The interior grade of the crawlspace below the flood protection elevation must not be more than two 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 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 and/or building related development below the flood protection elevation must be constructed with materials resistant to flood damage;
(g) Utility systems within the crawlspace and outside of the crawlspace including all electrical, heating, ventilating, plumbing, air conditioning equipment, and utility meters on the property, must be elevated above the flood protection elevation except for the following:
1. Water and sewer pipes, electrical and telephone lines, submersible pumps, and other service facilities may be located below the flood protection elevation provided they are waterproofed;
2. Fuel storage tanks must either be elevated above the flood protection elevation or adequately anchored to prevent flotation following manufacturer’s recommendations and protected from flood debris impact.
(h) Footings shall be placed on undisturbed earth or a licensed professional engineer shall certify in writing that the building shall be reasonably safe from flooding.
(C) Manufactured homes or travel trailers to be permanently installed on site must be in conformance with the Zoning Ordinance and shall be:
(1) Elevated to or above the flood protection elevation; 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 Ill. Adm. Code 870.
(D) Travel trailers and recreational vehicles on site for more than 180 days per year shall meet the elevation requirements of division (C) above unless the following conditions are met:
(1) The vehicle must be either self-propelled or towable by a light duty truck. The hitch must remain on the vehicle at all times;
(2) The vehicle must not be attached to external structures such as decks and porches;
(3) The vehicle must be designed solely for recreation, camping, travel or seasonal use rather than as a permanent dwelling;
(4) The vehicle’s largest horizontal projections must be no larger than 400 square feet;
(5) The vehicle’s wheels must remain on the axles and with inflated tires;
(6) Air conditioning units must be attached to the frame so as to be safe for movement out of the floodplain;
(7) Propane tanks as well as electrical, water and sewage connections must be quick- disconnect. Propane tanks must also be either elevated above the flood protection elevation or adequately anchored to prevent flotation following manufacturer’s recommendations and protected from flood debris impact;
(8) The vehicle must be licensed and titled as a recreational vehicle or park model; and
(9) The vehicle must be either:
(a) Entirely supported by jacks rather than blocks; 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.
(E) Garages, sheds or other accessory structures constructed ancillary to a residential use may be permitted but must meet the building protection requirements of division (B) above unless the following conditions are met:
(1) The accessory structure must be non-habitable;
(2) The accessory structure must be used only for the storage of vehicles and tools and cannot be modified later into another use;
(3) The accessory structure must be located outside of the floodway or have the appropriate state and/or federal permits to be located within the floodway;
(4) The accessory structure must be on a residential lot and be accessory to an existing principal structure on the same lot;
(5) Below the flood protection elevation, the accessory structure must be built of materials not susceptible to flood damage;
(6) All utilities, plumbing, heating, air conditioning, and electrical must be elevated above the flood protection elevation except that water and sewer pipes, electrical and telephone lines, submersible pumps, and other service facilities may be located below the flood protection elevation provided they are waterproofed;
(7) The garage or shed must have at least one permanent opening on each wall not more than one foot above grade. The openings shall provide a total net area of not less than one square inch of opening for every one square foot of enclosed area subject to flooding below the base flood elevation. Insect screens may cover flood openings provided that the insect screen does not unduly impede the entry and exit of floodwaters;
(8) The accessory structure must have a market value or replacement cost of less than $15,000, whichever is greater, or be less than 576 square feet in area;
(9) The accessory structure shall be anchored to resist flotation and overturning. Footings shall be placed on undisturbed earth or a licensed professional engineer shall certify in writing that the building shall be reasonably safe from flooding;
(10) All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, etc.) shall be stored above the flood protection elevation; and
(11) The lowest floor elevation shall be documented and the owner advised of the flood insurance implications.
(F) Non-residential buildings and/or non-residential building related development may be structurally dry floodproofed (in lieu of elevation) to meet the building protection requirements of division (B) above provided a licensed professional engineer or licensed 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 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 shall be incorporated into the 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; and
(5) Footings shall be placed on undisturbed earth or a licensed professional engineer shall certify in writing that the building shall be reasonably safe from flooding.
(G) All buildings and/or building related development located upon a property, a portion of which is located in the floodplain, shall be protected from flood damage below the flood protection elevation. The requirements of division (B) above shall also apply with respect to the regulated situations. Residential or non-residential buildings can meet the building protection requirements by the following methods:
(1) The buildings shall be located not less than ten feet away from the floodplain, and the ground surrounding the building shall extend at least ten feet beyond the foundation before sloping below the flood protection elevation;
(2) The lowest floor (including basement) shall be at or above the flood protection elevation level; or
(3) All portions of the building below the flood protection elevation shall be constructed of materials resistant to flood damage with all utilities elevated above the flood protection elevation except that water and sewer pipes, electrical lines, and other service facilities may be located below the flood protection elevation provided that they are waterproofed.
(Ord. 13-09-1, passed 9-10-2013)