(a) Permitted development. This section applies to proposed development, redevelopment, site modification or building modification within a regulatory floodway. The regulatory floodway for the Skokie River shall be as delineated on the regulatory floodway maps designated by OWR. Only those uses and structures that meet the criteria in this section shall be permitted. All regulatory floodway modifications shall be the minimum necessary to accomplish the purpose of the project. The development also shall meet all applicable requirements of § 9-101.
(b) Development permit. No person, firm, corporation or governmental body not exempted by state law shall commence any development in a regulatory floodway without first obtaining a development permit therefor from the building commissioner.
(c) Application. Application for a development permit shall be made on a form provided by the building commissioner. The applicant shall submit a completed application to the building commissioner and shall forward a copy of such application to the village engineer. The building commissioner shall determine, and the applicant shall submit, an appropriate application fee, taking into account the village engineer's cost of review and other village expenses incurred in issuing the permit. The application shall include the following information:
(1) Name and address of applicant;
(2) Site location (including legal description) of the property, drawn to scale, on the regulatory floodway map, indicating whether it is proposed to be in an incorporated or unincorporated area;
(3) Name of stream or body of water affected;
(4) Description of proposed activity;
(5) Statement of purpose of proposed activity;
(6) Anticipated dates of initiation and completion of activity;
(7) Name and mailing address of the owner of the subject property if different from the applicant;
(8) Signature of applicant or the applicant's agent;
(9) If the applicant is a corporation, the president or other authorized officer shall sign the application form;
(10) If the applicant is a partnership, each partner shall sign the application form;
(11) If the applicant is a land trust, the trust officer shall sign the name of the trustee by him or her as trust officer. A disclosure affidavit shall be filed with the application, identifying each beneficiary of the trust by name and address and defining the respective interests therein;
(12) Plans of the proposed activity shall be provided which include as a minimum:
A. A vicinity map showing the site of the activity, name of the waterway, boundary lines, names of roads in the vicinity of the site, graphic or numerical scale and north arrow;
B. A plan view of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the structure or work, elevations in NAVD 88, adjacent property lines and ownership, drainage and flood control easements, distance between the proposed activity and navigation channels (when the proposed construction is near a commercially navigable body of water), regulatory floodway limit, floodplain limit, location and orientation of cross-sections, north arrow and a graphic or numerical scale;
C. Cross-section views of the project and engineering study reach showing existing and proposed conditions, including without limitation principal dimensions of the work as shown in plain view, existing and proposed elevations, normal water elevation, ten-year frequency flood elevation, 100-year frequency flood elevation and graphic or numerical scales (horizontal and vertical); and
D. A copy of the regulatory floodway map, marked to reflect any proposed change in the regulatory floodway location;
(13) Any and all other federal, state and local permits or approval letters that may be required for this type of development;
(14) Engineering calculations and supporting data shall be submitted showing that the proposed work will meet the permit criteria of subsection 9-99(g) below;
(15) If the regulatory floodway delineation, base flood or 100 year frequency flood elevation will change due to the proposed project, the application will not be considered complete until OWR has indicated conditional approval of the regulatory floodway map change. No structures may be built until a letter of map revision has been approved by FEMA; and
(16) The application for a structure shall be accompanied by drawings of the site, drawn to scale, showing property line dimensions and existing ground elevations and all changes in grade resulting from any proposed excavation or filling, and floodplain and floodway limits, sealed by a registered land surveyor; the location and dimensions of all buildings and additions to buildings; and the elevation of the lowest floor (including basement) of all proposed buildings subject to the requirements of § 9-101.
(d) Other permit requirements. The applicant shall provide to the building commissioner and to the village engineer copies of all other federal, state and local permits and approvals that are required for this type of activity. The building commissioner shall be responsible for obtaining from the applicant all other federal, state and local permits and approvals that are required for this type of activity. The building commissioner shall not issue the development permit unless all required federal, state and local permits have been obtained.
(e) Review of floodplain administrator. The floodplain administrator shall review and approve applications submitted under this § 9-99.
(f) Preventing increased damages; appropriates uses. The only development in a regulatory floodway that shall be allowed are appropriate uses, which shall not cause a rise in the base flood elevation, and which shall not create a damaging or potentially damaging increase in flood heights or velocity or be a threat to the public health, safety or welfare. Only those appropriate uses listed in 92 Ill. Admin. Code § 708.70 shall be allowed. Appropriate uses do not include the construction or placement of any new structures, fill, building additions, buildings on stilts, fencing, landscaping or planting designed to act as a fence, and storage of material except as specifically defined above as an appropriate use. The approved appropriate uses are as follows:
(1) Flood control structures, dikes, dams and other public works or private improvements relating to the control of drainage, flooding, erosion or water quality or habitat for fish and wildlife;
(2) Structures or facilities relating to the use of or requiring access to the water or shoreline, such as pumping and treating facilities, and facilities and improvements related to recreational boating, commercial shipping, and other functionally water dependent uses;
(3) Storm and sanitary sewer outfalls;
(4) Underground and overhead utilities;
(5) Recreational facilities such as playing fields and trail systems, including any related fencing (at least 50% open when viewed from anyone direction) built parallel to the direction of flood flows, and including open air pavilions and toilet facilities (four stall maximum) that will not block flood flows nor reduce floodway storage;
(6) Detached garages, storage sheds or other non-habitable accessory structures without toilet facilities to existing buildings that will not block flood flows, nor reduce regulatory floodway storage;
(7) Bridges, culverts, roadways, sidewalks, railways, runways and taxiways and any modifications thereto;
(8) Parking lots and any modifications thereto (where depth of flooding at the 100-year frequency flood event will not exceed one foot, and aircraft parking aprons built at or below ground elevation);
(9) Regulatory floodway regrading, without fill, to create a positive non-erosive slope toward a watercourse;
(10) Flood proofing activities to protect previously existing lawful structures, including without limitation the construction of water tight window wells, elevating structures or floodwalls around residential, commercial or industrial principal structures, when the outside toe of the floodwall is no more than ten feet away from the exterior wall of the existing structure and which are not considered substantial improvements to the structure;
(11) In the case of damaged or replacement buildings, reconstruction or repairs made to a building that are valued at less than 50% of the market value of the building before it was damaged or replaced and do not increase the outside dimensions of the building;
(12) Additions to existing buildings above the base flood elevation that do not increase a building’s footprint and are valued at less than 50% of the market value of the building; and
(13) Appropriate uses do not include the construction or placement of any new buildings, fill, building additions, buildings on stilts, excavation or channel modifications done to accommodate otherwise non-appropriate uses in the floodway, fencing (including landscaping or planting designed to act as a fence) and storage of materials except as specifically defined above as an appropriate use.
(g) Engineering and mitigation criteria. Within the regulatory floodway as identified on the regulatory floodway maps designated by OWR, the construction of an appropriate use will be considered permissible provided that the proposed project meets the following engineering and mitigation criteria and is so stated in writing with supporting plans, calculations and data by a registered professional engineer, and provided further that any structure meets the protection requirements of § 9-101.
(1) Preservation of flood conveyance so as not to increase flood stages upstream. For appropriate uses other than bridge or culvert crossings, on-stream structures or dams, all effective regulatory floodway conveyance lost shall be replaced for all flood events up to and including the 100-year frequency flood. In calculating effective regulatory floodway conveyance, the following factors shall be taken into consideration:
A. Regulatory floodway conveyance.
"K" = 1.486 AR 2/3
n
n
where "n" is Manning's roughness factor, "A" is the effective area of the cross-section and "R" is the ratio of the area to the wetted perimeter.
B. The same Manning's "n" value shall be used for both existing and proposed conditions unless a recorded maintenance agreement with a federal, state or local unit of government can assure the proposed conditions will be maintained or the land cover is changing from a vegetative to a non-vegetative land cover.
C. Transition sections shall be provided and used in calculations of effective regulatory floodway conveyance. The following expansion and contraction ratios shall be used unless an applicant's engineer can prove to OWR through engineering calculations or model tests that more abrupt transitions may be used with the same efficiency:
1. When water is flowing from a narrow section to a wider section, the water should be assumed to expand no faster than at a rate of one foot horizontal for every four feet of the flooded stream's length;
2. When water is flowing from a wide section to a narrow section, the water should be assumed to contract no faster than at a rate of one foot horizontal for every one foot of the flooded stream's length;
3. When expanding or contracting flows in a vertical direction, a minimum of one foot vertical transition for every ten feet of stream length shall be used;
4. Transition sections shall be provided between cross-sections with rapid expansions and contractions and when meeting the regulatory floodway delineation on adjacent properties; and
5. All cross-sections used in the calculations shall be located perpendicular to flood flows.
(2) Preservation of regulatory floodway storage so as not to increase downstream flooding. Compensatory storage shall be provided for any regulatory floodway storage lost due to the proposed work from the volume of fill or structures placed and the impact of any related flood control projects. Compensatory storage for fill or structures shall be at least equal to one and one-half times the volume of floodplain storage lost. Artificially created storage lost due to a reduction in head loss behind a bridge shall not be required to be replaced. The compensatory regulatory floodway storage shall be placed between the proposed normal water elevation and the proposed 100-year flood elevation. All regulatory floodway storage lost below the existing ten-year flood elevation shall be replaced below the proposed ten-year flood elevation. All regulatory floodway storage lost above the existing ten-year flood elevation shall be replaced above the proposed 10-year flood elevation. All excavations described in this subsection 9-99(g)(2) shall be constructed to drain freely and openly to the watercourse. If the compensatory storage will not be placed at the location of the proposed construction, then the applicant's engineer shall demonstrate to OWR through a determination of flood discharges and water surface elevations that the compensatory storage is hydraulically equivalent. There shall be no reduction in regulatory floodway surface area as a result of a regulatory floodway modification, unless such modification is necessary to reduce flooding at existing structures.
(3) Preservation of regulatory floodway velocities so as not to increase stream erosion or flood heights. For all appropriate uses, except bridges or culverts or on-stream structures, the proposed work shall not result in an increase in the average channel or regulatory floodway velocities or stage for all flood events up to and including the 100-year frequency flood event. In the case of bridges or culverts or on-stream structures built for the purpose of backing up water in the stream during normal or flood flows, velocities may be increased at the structure site if scour, erosion and sedimentation will be avoided by the use of riprap or other design measures.
(4) Construction of new bridges or culvert crossings and roadway approaches. The proposed structure shall not result in an increase of upstream flood stages greater than one-tenth foot when compared to the existing conditions for all flood events up to and including the 100-year frequency flood event; or the upstream flood stage increases shall be contained within the channel banks (or within existing vertical extensions of the channel banks) such as within the design protection grade of existing levees or flood walls or within recorded flood easements. If the proposed construction will increase upstream flood stages greater than one-tenth foot, then the developer must contact OWR, Dam Safety Section, for a dam safety permit or waiver.
A. The engineering analysis of upstream flood stages shall be calculated using the flood study flows and corresponding flood elevations for tailwater conditions for the flood study specified in § 9-97. Culverts must be analyzed using the United States Department of Transportation, Federal Highway Administration Hydraulic Chart for the Selection of Highway Culverts. Bridges must be analyzed using the United States Department of Transportation, Federal Highway Administration Hydraulics of Bridge Waterways calculation procedures.
B. Lost regulatory floodway storage must be compensated pursuant to the requirements of subsection 9-99(g)(2).
C. Velocity increases must be mitigated pursuant to the requirements of subsection 9-99(g)(3).
D. If the crossing is proposed over a public water that is used for recreational or commercial navigation, an Illinois Department of Transportation permit must be received.
E. The hydraulic analysis for the backwater caused by the bridge showing the existing condition and proposed regulatory profile must be submitted to OWR for concurrence that a conditional letter of map revision from FEMA is not required by this subsection 9-99(g).
F. All excavations for the construction of the crossing shall be designed pursuant to the requirements of subsection 9-99(g)(8).
(5) Reconstruction or modification of existing bridges, culverts and approach roads.
A. The bridge or culvert and roadway approach reconstruction or modification shall be constructed with no more than a one-tenth foot increase in backwater over the existing flood profile for all flood frequencies up to and including the 100-year frequency flood event, if the existing structure is not a source of flood damage.
B. If the existing bridge or culvert and roadway approach is a source of flood damage to buildings or structures in the upstream floodplain, then the applicant's engineer shall evaluate the feasibility of redesigning the structure to reduce the existing backwater, taking into consideration the effects on flood stages on upstream and downstream properties.
C. The determination as to whether or not the existing crossing is a source of flood damage and should be redesigned must be prepared in accordance with 17 Ill. Admin. Code §§ 3708 et seq. and submitted to the OWR for review and concurrence before a permit is issued.
(6) On-stream structures built for the purpose of backing up water. Any increase in upstream flood stages over existing conditions for all flood events up to and including the 100-year frequency flood event shall be contained within the channel banks (or within existing vertical extensions of the channel banks) such as within the design protection grade of existing levees or flood walls or within recorded flood easements. A permit or permit-not-required letter must be obtained from OWR, Dam Safety Section, for a dam safety permit or waiver for any structure built for the purpose of backing up water in the stream during normal or flood flow. All dams and impoundment structures defined in § 9-95 shall meet the permitting requirements of 17 Ill. Admin. Code §§ 3708 et seq.
(7) Flood proofing of existing habitable residential and commercial structures. If construction is required beyond the outside dimensions of the existing building, the outside perimeter of the flood proofing construction shall be placed no further than ten feet from the outside of the building. Compensation of lost storage and conveyance will not be required for flood proofing activities.
(8) Excavation in the regulatory floodway. When excavation is proposed in the design of bridges and culvert openings, including without limitation the modifications to and replacement of existing bridge and culvert structures or to compensate for lost conveyance for other appropriate uses, transition sections shall be provided for the excavation. The following expansion and contraction ratios shall be used unless an applicant's engineer can prove to OWR through engineering calculations or model tests that more abrupt transitions may be used with the same efficiency:
A. When water is flowing from a narrower section to a wider section, the water should be assumed to expand no faster than at a rate of one foot horizontal for every four feet of the flood stream's length;
B. When water is flowing from a wider section to a narrower section, the water should be assumed to contract no faster than at a rate of one foot horizontal for every one foot of the flooded stream's length;
C. When expanding or contracting flows in a vertical direction, a minimum of one foot vertical transition for every ten feet of stream length shall be used; and
D. Erosion and scour protection shall be provided inland upstream and downstream of the transition sections.
(9) Seeding and stabilization plan. For all activities located in a regulatory floodway, a seeding and stabilization plan shall be submitted by the applicant.
(10) Public flood control projects. For public flood control projects, the permitting requirements of this § 9-99 shall be considered met if the applicant can demonstrate to OWR through hydraulic and hydrologic calculations that the proposed project shall not singularly or cumulatively result in increased flood heights outside the project right-of-way or easements for all flood events up to and including the 100-year frequency event.
(11) General criteria for analysis of flood elevations.
A. The flood profiles, flows and floodway data in the regulatory floodway study referenced in § 9-97 must be used for analysis of the base conditions. If the study data appears to be in error or conditions have changed, OWR shall be contacted for approval and concurrence on the appropriate base conditions data to use.
B. If the base flood elevation at the site of the proposed construction is affected by backwater from a downstream receiving stream with a larger drainage area, the proposed construction shall be shown to meet the requirements of this § 9-99 for the base flood elevations of the regulatory floodway conditions and conditions with the receiving stream at normal water elevations.
C. If the applicant learns from OWR, local governments, or a private owner that a downstream restrictive bridge or culvert is scheduled to be removed, reconstructed or modified, or a regional flood control project is scheduled to be built, removed, constructed or modified within the next five years, the proposed construction shall be analyzed and shown to meet the requirements of this § 9-99 for both the existing conditions and the expected flood profile conditions when the bridge, culvert or flood control project is built.
(h) Conditional letter of map revision. If the appropriate use would result in a change in the regulatory floodway location or the 100-year frequency flood elevation, the applicant shall submit to OWR and to FEMA all the information, calculations and documents necessary to be issued a conditional regulatory floodway map revision and receive from OWR a conditional approval of the regulatory floodway change before a permit is issued; provided, however, that the final regulatory floodway map will not be changed by OWR until as-built plans or record drawings are submitted and accepted by FEMA and OWR. In the case of non-government projects, the municipality in incorporated areas and the county in unincorporated areas shall concur with the proposed conditional regulatory floodway map revision before OWR approval can be given. No filling, grading, dredging or excavating shall take place until a conditional approval is issued. No further development activities shall take place until a final letter of map revision is issued by FEMA and OWR.
(i) Professional engineer supervision. All engineering analyses shall be performed by or under the supervision of a registered professional engineer.
(j) Construction activity. After receipt of conditional approval of the regulatory floodway map change and issuance of a permit and a conditional letter of map revision, construction as necessary to change the regulatory floodway designation may proceed; provided, however, that no buildings or structures or other construction that is not an appropriate use may be placed in that area until the regulatory floodway map is changed and a final letter of map revision is received. The regulatory floodway map shall be revised upon acceptance and concurrence by OWR and FEMA of the as-built plans.
(k) State review. For those projects listed below located in a regulatory floodway, the following criteria shall be submitted to OWR for their review and concurrence prior to the issuance of a permit:
(1) OWR shall review an engineer's analysis of the flood profile due to a proposed bridge pursuant to subsection 9-99(g)(4);
(2) OWR shall review an engineer's determination that an existing bridge or culvert crossing is not a source of flood damage and the analysis indicating the proposed flood profile, pursuant to subsection 9-99(g)(5);
(4) OWR shall review and approve prior to the start of construction any Illinois Department of Transportation projects, dams and all other federal, state or local units of government projects, including projects of the village.
(l) Other permits. In addition to the requirements of this article XIV, a development permit for a site located in a regulatory floodway shall not be issued unless the applicant first obtains a permit or written documentation that a permit is not required, from OWR, issued pursuant to the Act. No permit from OWR shall be required if OWR has delegated this responsibility to the village.
(m) Dam safety permits. Any work involving the construction, modification or removal of a dam defined in § 9-95 shall obtain a OWR dam safety permit pursuant to 17 Ill. Admin. Code §§ 3702 et seq. prior to the start of such construction, modification or removal. If the building commissioner finds a dam that does not have a OWR permit, the building commissioner shall immediately notify the Dam Safety Section of OWR. If the building commissioner finds a dam that is believed to be in an unsafe condition, the building commissioner shall immediately notify the owner of the dam, if known, OWR, the Dam Safety Section in Springfield, Illinois and the Illinois Emergency Services and Disaster Agency (ESDA).
(n) Activities that do not require a registered professional engineer's review. The following activities may be permitted without a registered professional engineer's review; provided, however, that such activities shall meet the other requirements of this article XIV, including the mitigation requirements.
(1) Underground and overhead utilities:
A. That do not result in any increase in existing ground elevations;
B. That do not require the placement of aboveground structures in the regulatory floodway;
C. When, in the case of underground stream crossings, the top of the pipe or encasement is buried a minimum of three feet below the existing stream bed; and
D. When, in the case of overhead utilities, no supporting towers are placed in the watercourse and are designed in such a fashion as not to catch debris.
(2) Storm and sanitary sewer outfalls that:
A. Do not extend riverward or lakeward of the existing adjacent natural bank slope;
B. Do not result in an increase in ground elevation; and
C. Are so designed as not to cause stream erosion at the outfall location.
(3) Construction of sidewalks, athletic fields (excluding fences), properly anchored playground equipment and patios built at grade.
(4) Construction of shoreline and streambank protection:
A. That does not exceed 1,000 feet in length;
B. When materials are not placed higher than the existing top of bank; or
C. When materials are placed so as not to reduce the cross-sectional area of the stream channel or bank of the lake.
(5) Temporary stream crossings in which:
A. The approach roads will be one-half foot or less above natural grade;
B. The crossing will allow stream flow to pass without backing up the water above the stream bank vegetation line or above any drainage tile or outfall invert;
C. The top of the roadway fill in the channel will be at least two feet below the top of the lowest bank;
D. All disturbed stream banks will be seeded or otherwise stabilized as soon as possible upon installation and again upon removal of construction; and
E. The access road and temporary crossings will be removed within one year after authorization.
(Ord. No. 2021-16-3512)