Section 6. Preventing Increased Flood Heights and Resulting Damages.
Within any floodway identified on the countywide Flood Insurance Rate Map, and within all other floodplains where a floodway has not been delineated, the following standards shall apply:
A. Except as provided in Section 6(B) of this ordinance, 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:
1. Bridge and culvert crossings of streams in rural areas meeting the following conditions of the Illinois Department of Natural
Resources, Office of Water Resources Statewide Permit Number 2:
a. the crossing will not result in an increase in water surface profile elevation in excess of 1.0 feet, and
b. the crossing will not result in an increase in water surface profile elevation in excess of one half (0.5) feet at a point one thousand (1,000) feet upstream of the proposed structure.
c. There are no buildings in the area impacted by the increases in water surface profile.
d. The proposed bridge or culvert crossing will not involve straightening, enlarging, or relocating the
e. The design must be certified by a licensed professional engineer in the State of Illinois and the designs must meet the conditions of an IDNR/OWR permit.
f. The design must be certified by a second licensed professional engineer.
2. Barge fleeting facilities meeting the following conditions of IDNR/OWR Statewide Permit Number 3:
a. The permit is only applicable when deadmen, pier cells, or other similar anchorage devices have been permitted by the U.S. Army Corps of Engineers.
3. Aerial utility crossings meeting the following conditions of IDNR/OWR Statewide Permit Number 4;
a. The utility line must be constructed above the existing 1 00-year flood elevation or attached to an existing bridge.
b. A utility line attached to an existing bridge shall be constructed above the low cord elevation of the bridge.
c. No supporting towers or poles shall be located in a river, lake or stream.
d. Supporting towers including foundation and poles shall be designed and located so as to not cause an
obstruction of flood flows by trapping debris.
e. All disturbed areas shall be returned to pre-construction grades and re-vegetated.
f. All Illinois Commerce Commission, National Electrical Safety Code, and federal requirements must be met.
4. Minor boat docks meeting the following conditions of IDNR/OWR Statewide Permit Number 5:
a. The boat dock must not extend more than fifty (50) feet into a waterway and no more than one quarter (1/4) of the width of the waterway and shall not extend beyond the navigational limited established by the IDNR and Corps of Engineers.
1 The width of the boat dock shall not be more than ten (10) feet.
c. For L-Shaped or T-shaped docks, the length of that portion parallel to the shoreline must not exceed fifty percent (50%) of the landowner's shoreline frontage nor fifty (50) feet.
d. Docks must be aligned so as not to cross the projection of property lines into the waterway or come within ten (10) feet of the projected property line.
e. Dock posts must be marked by reflective devices.
f. The boat dock must be securely anchored to prevent detachment during times of high wind or water.
g. Metal drums or containers may not be used as buoyancy units unless they are filled with floatation foam. Containers which previously stored pesticides, herbicides, or any other toxic chemicals are not permissible.
h. This permit does not authorize any other related construction activity such as shore protection or fill.
i. Non-floating boat docks must be constructed in a maimer which will minimize obstruction to flow.
j. At any future date, the permittee must agree to make necessary modifications to the dock as determined by the IDNB. or Corp of Engineers
5. Minor, non-obstructive activities meeting the following conditions of IIDNRJOWR Statewide Permit Number 6:
a. the following activities (not involving fill or positive change in grade) are covered by this permit:
i. The construction of underground utility lines, wells, or septic tanks not crossing a lake or stream.
ii. The construction of light poles, sign posts, and similar structures.
iii. The construction of sidewalks, driveways, athletic fields (excluding fences), patios, and similar structures.
iv. The construction of properly anchored, unwalled, open structures such as playground equipment,
pavilions, and carports.
v. The placement of properly anchored buildings not exceeding seventy (70) square feet in size, nor ten (10) square feet in any dimension. Only one such building on a property is authorized by this statewide permit.
vi. The raising of existing buildings, provided no changes are made to the outside dimensions of the building and the placement of fill is not involved.
6. Outfall Structures and drainage ditch outlets meeting the following conditions of IDNR/OWR Statewide Permit Number 7:
a. My outfall structure, including any headwall or end- section, shall not extend riverward or lakeward of the existing adjacent natural bank slope or adjacent bank protection.
b. The velocity of the discharge shall not exceed the scour velocity of the channel soil, unless channel erosion would be prevented by the use of riprap or other design measures,
c. Outlets from drainage ditches shall not be opened to a stream until the ditch is vegetated or otherwise
stabilized to minimize stream sedimentation.
d. Disturbance of streamside vegetation shall be kept to a minimum during construction to prevent erosion and sedimentation. All disturbed floodway areas, including the stream banks, shall be restored to their original contours and seeded or otherwise stabilized upon completion of construction.
7. Underground pipeline and utility crossings meeting the conditions of IDNRIOWR Statewide Permit Number 8:
a. In all cases, the crossing shall be placed beneath the bed of the river, lake or stream and, unless the crossing is encased in concrete or entrenched in bedrock, a minimum of three (3) feet of cover shall be provided. The river, lake or stream bed shall be returned to its original condition.
b. Disturbance of streamside vegetation shall be kept to a minimum during construction to prevent erosion and sedimentation. All disturbed floodway areas, including stream banks, shall be restored to theft original contours and seeded or otherwise stabilized upon completion of construction.
c. Any utility crossing carrying material which may cause water pollution, as defined by the Environmental Protection Act (415 ILCS 5), shall be provided with shut-off valves on each side of the body of water to be crossed.
d. If blasting is to be utilized in the construction of the crossing, the permittee shall notit5' the IDNRJOWR at least ten (10) days prior to the blasting date to allow monitoring of any related fish kills.
8. Bank stabilization projects meeting the conditions of IDNRJOWR Statewide Permit Number 9:
a. Only the following materials may be utilized in urban areas: stone and concrete riprap, steel sheet piling, cellular blocks, fabric-formed concrete, gabion baskets, rock and wire mattresses, sand/cement filled bags, geotechnical fabric materials, natural vegetation and treated timber. Urban areas are defined as: areas of the State where residential, commercial, or industrial development currently exists or, based on land use plans or controls, is expected to occur within ten (10) years. (The Department should be consulted if there is a question of whether or not an area is considered urban).
b. In addition to the materials listed in Section 6 (A)(8)(a), other materials (e.g. tire revetments) may be utilized in rural areas provided all other conditions of this permit are met.
c. The following materials shall not be used in any case:
auto bodies, garbage of debris, scrap lumber, metal refuse, roofing materials, asphalt or other bituminous materials, or any material which would cause water pollution as defined by the Environmental Protections Act (415 ILCS 5).
d. The affected length of shoreline, stream bank, or channel to be protected shall not exceed, either singularly or cumulatively, one thousand (1000) feet.
e. All material utilized shall be properly sized or anchored to resist anticipated forces of current and wave action.
£ Materials shall be placed in a way which would not cause erosion or the accumulation of debris on properties adjacent to or opposite the project.
g. Materials shall not be placed higher than the existing top of the bank.
h. Materials shall be placed so that the modified bank f width and cross-sectional area of the channel will conform to or be no more restrictive than that of the natural channel upstream and downstream of the site.
For projects involving continuous placement of riprap along the bank, toe of the bank or other similar applications, in no ciase shall the cross-sectional area of the natural channel be reduced by more than ten percent (10%) nor the volume of material placed exceed two. (2) cubic yards per lineal foot of the stream bank or shoreline. The bank may be graded to obtain a flatter slope and to lessen the quantity of material required.
1. If broken concrete is used, all protruding materials such as reinforcing rods shall be cut flush with the surface of the concrete and removed from the construction area.
j. Disturbance of vegetation shall be kept to a minimum during construction to prevent erosion and sedimentation. All disturbed areas shall be seeded or otherwise stabilized upon completion of construction.
k. In the case of seawalls and gabion structures on lakes, the structure shall be constructed at or landward of the water line as determined by the nonnal pool elevation, unless:
i. It is constructed in alignment with an existing seawall(s) or gabion structure(s), and
ii. the volume of material placed, including the structure, would not exceed two (2) cubic yards per lineal foot.
l. Excess material excavated during the construction of the bank or shoreline protection shall be placed in accordance with local, state, and federal laws and rules, shall not be placed in a floodway.
9. Accessory structures and additions to existing residential buildings meeting the conditions of IDNR/OWR Statewide Pemit Number 10:
a. The accessory structure or building addition must comply with the requirements of the local floodplain ordinance.
b. The principle structure to which the project is being added must have been in existence on the effective date of this permit (July 25, 1988).
c. The accessory structure or addition must not exceed five hundred (500) square feet in size and must not deflect floodwaters onto another property, and
d. must not involve the placement of any fill material.
e. No construction shall be undertaken in, or within fifty (50) feet of the bank of the stream channel.
f. The accessory structure or addition must be properly anchored to prevent its movement during flood conditions.
g. Only one accessory structure or addition to an existing structure shall be authorized by this permit; plans for any subsequent addition must be submitted to IDNR/OWR for review.
h. Disturbances of vegetation shall be kept to a minimum during construction to prevent erosion and sedimentation. All disturbed floodway areas shall be seeded or otherwise stabilized upon completion of construction.
10. Minor maintenance dredging activities meeting the following conditions of IDNR/OWR Statewide Permit Number 11:
a. The affected length of the strewn shall not either singularly or cumulatively exceed one thousand (1000) feet.
b. The project shall not include the construction of any new channel; all work must be confined to the existing channel or to reestablishing flows in the natural stream channel, and
c. the cross-sectional area of the dredged channel shall conform to that of the natural channel upstream and down stream of the site.
d. Dredged or spoil material shall not be disposed of in a wetland and shall be either:
i. removed from the floodway;
ii. used to stabilize an existing bank provided no materials would be placed higher than the existing top of bank and provided the cross-sectional area of the natural channel would not be reduced by more than ten percent (10%), nor the volume of material placed exceed two (2) cubic yards per lineal foot of streambank;
iii. used to fill an existing washed out or scoured floodplain area such that the avenge natural floodplain elevation is not increased;
iv. used to stabilize and existing levee provided the height of the levee would not be increased nor its alignment changed;
v. placed in a disposal site previously approved by the Department in accordance with the conditions of the approval, or
vi. used for beach nourishment, provided the material meets all applicable water quality standards.
e. Disturbance of streamside vegetation shall be kept to a minimum during construction to prevent erosion and sedimentation. All disturbed floodway areas, including the stream banks, shall be seeded or otherwise stabilized upon completion of construction.
11. Bridge and culvert replacement structures and bridge widening meeting the following conditions of IDNR/OWR statewide Permit Number 12:
a. A licensed professional engineer shall determine and document that the existing structure has not been the cause of demonstrable flood damage. Such documentation shall include, at a minimum, confirmation that:
i. No buildings or structures have been impacted by the backwater induced by the existing structure, and
ii. there is no record of complaints of flood damages associated with the existing structure.
b. A licensed professional engineer shall detennine that the new structure will provide the same or greater effective waterway opening as the existing structure. For bridge widening projects the existing piers and the proposed pier extensions must be in line with the direction of the approaching flow upstream of the bridge.
c. The project shall not include any appreciable raising of the approach roads. (This condition does not apply if all points on the approaches exist at an elevation equal to or higher than the 100-year frequency flood headwater elevation as determined by a FEMA flood insurance study completed or approved by IDNR/OWR).
d. The project shall not involve the straightening, enlargement or relocation of the existing channel of the river or stream except as permitted by the Department's Statewide Permit Number 9 (Minor Shoreline, channel and Streambank Protection Activities) or Statewide Permit Number 11 (Minor Maintenance Dredging Activities).
e. The permittee shall maintain records of projects authorized by this permit necessary to document
compliance with the above conditions.
12. Temporary construction activities meeting the following conditions of IDNRJOWR statewide Permit Number 13:
a. No temporary construction activity shall be commenced until the individual pennittee determines that the permanent structure (if any) for which the work is being performed has received all required federal, state and local authorizations.
b. The term "temporary" shall mean not more than one construction season. MI temporary construction materials must be removed from the stream and floodway within one year of their placement and the area returned to the conditions existing prior to the beginning of construction. My desired subsequent or repetitive material placement shall not occur without the review and approval of the IDNR/OWR.
c. The temporary project shall be constructed such that it will not cause erosion or damage due to increases in water surface profiles to adjacent properties. For locations where there are structures in the upstream floodplain, the temporary project shall be constructed such that all water surface profile increases, due to the temporary project, are contained within the channel banks.
d. This permit does not authorize the placement or construction of any solid embankment or wall such as a dam, roadway, levee, or dike across any channel or floodway.
e. No temporary structure shall be placed within any river or stream channel until a licensed professional engineer determines and documents that the temporary structure will meet the requirements of Special Condition Number 3 of this statewide permit. Such documentation shall include, at a minimum, confirmation that no buildings or structures will be impacted by the backwater induced by the temporary structure.
f. The permittee shall maintain records of projects authorized by this permit necessary to document compliance with the above condition.
g. Disturbance of vegetation shall be kept to a minimum during construction to prevent erosion and sedimentation. All disturbed areas shall be seeded or otherwise stabilized upon completion of the removal of the temporary construction.
h. Materials used for the project shall not cause water pollution as defined by the Environmental Protection Act (415 ILCS 5).
13. Any Development determined by IDNRJOWR to be located entirely within a flood fringe area shall be exempt from State Floodway permit requirements.
B. Other development activities not listed in 6(A) may be permitted only if:
14. permit has been issued for the work by IDNR/OWR (or written documentation is provided that an IDNR/OWR permit is not required), or
15. sufficient data has been provided to FEMA when necessary, and approval obtained from FEMA for a revision of the regulatozy map and base flood elevation.
Section 7. Protecting Buildings.
A. In addition to the damage prevention requirements of Section 6 of this ordinance, 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:
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 the market value by fifty percent (50%). Alteration shall be figured cumulatively adoption of this ordinance. 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 subsequent to the adoption of this ordinance. If substantially damaged the entire structure must meet the flood protection standards of this section.
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 manuThvtured home to the same site it lawfully occupied before it was removed to avoid flood damage).
5. Installing a travel trailer or recreational vehicle on a site for more than one hundred eighty (180) days per year.
6. Repetitive loss to an existing building as defmed in Section 2.
B. Residential or non-residential buildings can meet the building protection requirements by one of the following methods:
7. The building 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. The fill shall be placed in layers no greater than six inches before compaction and should 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, riprap, or other structural measure.
d. The fill shall be composed of rock or soil and not incorporated debris or refuse material, and
e. 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.
8. 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. 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 flood protection elevation 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 (I) square inch for every one (1) square foot of enclosed area subject to flooding below the base flood elevation, and
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.
i. All structural components below the flood protection elevation shall be constructed of materials resistant to flood damage.
ii. 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.
iii. 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
iv. in lieu of the above criteria, the design methods to comply with these requirements may be certified by a licensed professional engineer or architect.
9. The building may be constructed with a crawispace located below the flood protection elevation provided that the following conditions are met:
10. 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.
11. 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.
12. 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.
13. The interior height of the crawispace measured from the interior grade of the crawl to the top of the foundations wall must not exceed four (4) feet at any point.
14. An adequate drainage system must be installed to remove floodwaters from the interior area of the craw within a reasonable period of time after a flood event.
15. Portions of the building below the flood protection elevation must be constructed with materials resistant to flood damage, and
16. utility systems within the crawlspace must be elevated above the flood protection elevation.
C. Non-residential buildings may be structurally dry floodproofed (in lieu of elevation) provided a licensed professional engineer or architect certifies that:
17. Below the flood protection elevation the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood.
18. The building design accounts for flood velocities, duration, rate of rise, hydrostatic and hydrodynanic forces, the effects of buoyancy, and the impact from debris and ice.
19. Floodproofing measures will be incorporated into the building design and operable without human intervention and without an outside source of electricity.
20. Levees, berms, floodwalls and similar works are not considered floodproofing for the purpose of this subsection.
D. Manufactured homes or travel trailers to be permanently installed on site shall be:
2. Elevated to or above the flood protection elevation in accordance with Section 7(B), and
3. 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 77111. Adm. Code §
E. Travel trailers and recreational vehicles on site for more than one hundred eighty (180) days per year shall meet the elevation requirements of section 7 (D) unless the following conditions are met:
4. The vehicle must be either self-propelled or towable by a light duty truck.
5. The hitch must remain on the vehicle at all times.
6. The vehicle must not be attached to external structures such as decks and porches
7. The vehicle must be designed solely for recreation, camping, travel, or seasonal use rather than as a permanent dwelling.
8. The vehicles largest horizontal projections must be no larger than four hundred (400) square feet.
9. The vehicle's wheels must remain on axles and inflated.
10. Air conditioning units must be attached to the frame so as to be safe for movement of the floodplain.
11. Propane tanks as well as electrical and sewage connections must be quick-disconnect and above the 100-year flood elevation.
12. The vehicle must be licensed and titled as a recreational vehicle or park model, and
13. 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 used of the hitch jack.
F. Garages, sheds or other minor accessory structures constructed ancillary to an existing residential use may be permitted provided the following conditions are met:
14. The garage of shed must be non-habitable.
15. The garage or shed must be used only for the storage of vehicles and tools and cannot be modified later into another use.
16. The garage or shed must be located outside of the floodway or have the appropriate state and/or federal permits.
17. The garage or shed must be on a single family lot and be accessory to an existing principle structure on the same lot.
18. Below the base flood elevation, the garage or shed must be built of materials not susceptible to flood damage.
19. All utilities, plumbing, heating, air conditioning and electrical must be elevated above the flood protection elevation.
20. The garage or shed must have at least one permanent opening on each wall not more than one (1) foot above grade with one (1) square inch of opening for every one (1) square foot of floor area.
21. The garage or shed must be less than ten thousand dollars ($10,000) in market value or replacement cost whichever is greater or less than five hundred (500) square feet.
22. The structure shall be anchored to resist floatation and overturning.
23. All flammable or toxic materials (gasoline, paint, insecticides, fertilizers, etc.) shall be stored above the flood protection elevation.
24. The lowest floor elevation should be documented and the owner advised of the flood insurance implications.