A. Purposes: Flood management accomplishes the following purposes:
1. To prevent unwise developments from increasing flood or drainage hazards to others;
2. To protect new buildings and major improvements to buildings from flood damage;
3. To promote and protect the public health, safety, and general welfare of the citizens from the hazards of flooding;
4. To lessen the burden on the taxpayer for flood control, repairs to public facilities and utilities, and rescue and relief operations;
5. To maintain property values and a stable tax base by minimizing the potential for creating blight areas;
6. To make property values and a stable tax base by minimizing the potential for creating blight areas; and
7. To preserve the natural characteristics and functions of watercourses and floodplains in order to moderate flood and storm water impacts, improve water quality, reduce soil erosion, protect aquatic and riparian habitat, provide recreational opportunities, and provide aesthetic enhancement to the area.
B. Preventing Increased Flood Heights And Resulting Damages: Within the floodway identified on the flood insurance rate map, and within all other floodplains where a floodway has not been delineated, the following standards shall apply:
1. Except as provided in subsection B2 of this section, no development shall be allowed which, acting in combination with existing and anticipated development, will cause any increase in flood heights or velocities or threat to public health and safety. The following specific development activities shall be considered as meeting this requirement:
a. Bridge and culvert crossings of streams in rural areas meeting the conditions of the IDNR/OWR statewide permit no. 2.
b. Barge fleeting facilities meeting the conditions of IDNR/OWR statewide permit no. 3;
c. Aerial utility crossings meeting the conditions of IDNR/OWR statewide permit no. 4;
d. Minor boat docks meeting the conditions of IDNR/OWR statewide permit no. 5
e. Minor, nonobstructive activities meeting the conditions of the IDNR/OWR statewide permit no. 6;
f. Outfall structures and drainage ditch outlets meeting the conditions of IDNR/OWR statewide permit no. 7;
g. Underground pipeline and utility crossings meeting the conditions of IDNR/OWR statewide permit no. 8;
h. Bank stabilization projects meeting the conditions of IDNR/OWR statewide permit no. 9;
i. Accessory structures and additions to existing residential buildings meeting the conditions of IDNR/OWR statewide permit no. 10;
j. Minor maintenance dredging activities meeting the conditions of IDNR/OWR statewide permit no. 11;
k. Bridge and culvert replacement structures and bridge widening meeting the conditions of IDNR/OWR statewide permit no. 12;
l. Temporary construction activities meeting the conditions of IDNR/OWR statewide permit no. 13; and
m. Any development determined by IDNR/OWR to be located entirely within a flood fringe area.
2. Other development activities not listed in subsection B1 of this section may be permitted only if:
a. Permit has been issued for the work by IDNR/OWR (or written documentation is provided that an IDNR/OWR permit is not required), or
b. Sufficient data has been provided to FEMA when necessary, and approval obtained from FEMA for a revision of the regulatory map and base flood elevation.
C. Protected Buildings:
1. In addition to the state permit and damage prevention requirements of subsection B of this section, all buildings located in the floodplain shall be protected from flood damage below the flood protection elevation. This building protection requirement applies to the following situations:
a. Construction or placement of a new building or alteration or addition to an existing building valued at more than one thousand dollars ($1,000.00) or seventy (70) square feet.
b. 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 the market value by fifty percent (50%). Alteration shall be figured cumulatively subsequent to the adoption of this section 8-4-5. If substantially improved, the existing structure and the addition must meet the flood protection standards of this section.
c. Repairs made to a substantially damaged building shall be figured cumulatively subsequent to the adoption of this section 8-4-5. 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.
d. 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.)
e. Installing a travel trailer or recreational vehicle on a site for more than one hundred eighty (180) days per year.
f. "Repetitive loss" to an existing building as defined in this section 8-4-5.
2. Residential or nonresidential buildings can meet the building protection requirements by one of the following methods:
a. The building 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 six inches (6") before compaction and should extend at least ten feet (10') beyond the foundation before sloping below the flood protection elevation,
(3) The fill shall be protected against erosion and scour during flooding by vegetative cover, riprap, or other structural measure,
(4) The fill shall be composed of rock or soil and not incorporated debris or refuse material, and
(5) 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.
b. The building may be elevated in accordance with the following:
(1) The building or improvements shall be elevated on stilts, piles, walls, crawl space, or other foundation that is permanently open to floodwaters.
(2) 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.
(3) If walls are used, 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 to ensure hydrostatic flood forces on walls are automatically equalized by allowing the entry and exit of floodwaters or by having a minimum of one permanent opening on each wall no more than one foot (1') above grade with a minimum of two (2) openings. 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 base flood elevation, and
(4) The foundation and supporting members of all new construction and substantial improvements shall be designed (or modified) and adequately anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
(5) All structural components below the flood protection elevation shall be constructed of materials resistant to flood damage.
(6) 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 area below the flood protection elevation shall be used solely for parking or building access and not later modified or occupied as habitable space, or
c. The building may be constructed with a crawl space located below the flood protection elevation provided that the following conditions are met:
(1) 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.
(2) 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 square inch per one square foot of enclosed area. The openings shall be no more than one foot (1') above grade.
(3) The interior grade of the crawl space below the flood protection elevation must not be more than two feet (2') below the lowest adjacent exterior grade.
(4) The interior height of the crawl space measured from the interior grade of the crawl to the top of the foundations wall must not exceed four feet (4') at any point.
(5) An adequate drainage system must be installed to remove floodwaters from the interior area of the crawl space within a reasonable period of time after a flood event.
(6) Portions of the building below the flood protection elevation must be constructed with materials resistant to flood damage, and
(7) Utility systems within the crawl space must be elevated above the flood protection elevation.
3. Nonresidential buildings may be structurally dry floodproofed (in lieu of elevation) provided a licensed professional engineer or architect certifies that:
a. Below the flood protection elevation the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood.
b. 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.
c. 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 section.
5. Manufactured homes or travel trailers to be permanently installed on site shall be:
a. Elevated to or above the flood protection elevation in accordance with subsection C2 of this section, and
b. 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 section 870.
6. Travel trailers and recreational vehicles on site for more than one hundred eighty (180) days per year shall meet the elevation requirements of subsection C5 of this section, unless the following conditions are met:
a. The vehicle must be either self-propelled or towable by a light duty truck,
b. The hitch must remain on the vehicle at all times,
c. The vehicle must not be attached to external structures such as decks and porches,
d. The vehicle must be designed solely for recreation, camping, travel, or seasonal use rather than as a permanent dwelling,
e. The vehicle's largest horizontal projections must be no larger than four hundred (400) square feet,
f. The vehicle's wheels must remain on axles and inflated,
g. Air conditioning units must be attached to the frame so as to be safe for movement from the floodplain,
h. Propane tanks as well as electrical and sewage connections must be quick disconnect,
i. The vehicle must be licensed and titled as a recreational vehicle or park model, and
j. Must either:
(1) Entirely be supported by jacks, or
(2) 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.
7. Garages, sheds or other minor accessory structures constructed ancillary to an existing residential use may be permitted to be constructed with the lowest floor below the flood protection elevation provided the following conditions are met:
a. The garage or shed must be nonhabitable.
b. The garage or shed must be used only for the storage of vehicles and tools and cannot be modified later into another use.
c. The garage or shed must be located outside of the floodway or have the appropriate state and/or federal permits.
d. The garage or shed must be on a single-family lot and be accessory to an existing principal structure on the same lot.
e. Below the base flood elevation, the garage or shed must be built of materials not susceptible to flood damage.
f. All utilities, plumbing, heating, air conditioning and electrical must be elevated above the flood protection elevation.
g. The garage or shed must have at least one permanent opening on each wall not more than one foot (1') above grade with one square inch of opening for every one square foot of floor area.
h. The garage or shed must be less than fifteen thousand dollars ($15,000.00) in market value or replacement cost whichever is greater or less than five hundred seventy six (576) square feet (24 feet x 24 feet).
(1) The structure shall be anchored to resist flotation and overturning.
(2) All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, etc.) shall be stored above the flood protection elevation.
(3) The lowest floor elevation should be documented and the owner advised of the flood insurance implication.
D. Subdivision Requirements: The certified community shall take into account hazards, to the extent that they are known, in all official actions related to land management use and development.
1. New subdivisions, manufactured home parks, annexation agreements, planned unit developments, and additions to manufactured home parks and subdivisions shall meet the damage prevention and building protections standards of this section 8-4-5. Any proposal for such development shall include the following data:
a. The base flood elevation and the boundary of the floodplain, where the base flood elevation is not available from an existing study, the applicant shall be responsible for calculating the base flood elevation;
b. The boundary of the floodway when applicable; and
c. A signed statement by a licensed professional engineer in the state of Illinois that the proposed plat or plan accounts for changes in the drainage of surface waters in accordance with the plat act 1 .
2. Streets, blocks, lots, parks and other public grounds shall be located and laid out in such a manner as to preserve and utilize natural streams and channels. Wherever possible the floodplains shall be included within parks or other public grounds.
E. Public Health And Other Standards:
1. Public health standards must be met for all floodplain development. In addition to the requirements of subsections C and D of this section, the following standards apply:
a. No development in the floodplain shall include locating or storing chemicals, explosives, buoyant materials, flammable liquids, pollutants, or other hazardous or toxic materials below the flood protection elevation unless such materials are stored in a floodproofed and anchored storage tank and certified by a professional engineer or floodproofed building constructed according to the requirements of subsection D of this section.
b. Public utilities and facilities such as sewer, gas, and electric shall be located and constructed to minimize or eliminate flood damage.
c. Public sanitary sewer systems and water supply systems shall be located and constructed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters.
d. New and replacement on site sanitary sewer lines or waste disposal systems shall be located and constructed to avoid impairment to them or contamination from them during flooding. Manholes or other aboveground openings located below the flood protection elevation shall be watertight.
e. Critical facilities shall be protected to the 500-year flood elevation. In addition, all ingress and egress from any critical facility must be protected to the 500-year flood elevation.
2. All other activities defined as "development" shall be designed so as not to alter flood flows or increase potential flood damages. (Ord. 2016-003, 3-8-2016)
Notes
| 1 | 1. 765 ILCS 205/2. |