VILLAGE OF ADDISON CODE

Chapter 26 Stormwater and Floodplain Management

Article 3.  Floodplain Management.

Sec. 26-301.    Duties of the Enforcement Official. [back to top]

The Village Engineer shall be responsible for the general administration and enforcement of this Chapter, which shall include the following:

(A)       Determining the Floodplain Designation. Check all new development sites to determine whether they are in a Special Flood Hazard Area (SFHA).  If they are in a SFHA, determine whether they are in a floodway, flood fringe or in a floodplain on which a detailed study has not been conducted which drains more than one square mile.

(B)       Professional Engineer Review. If the development site is within a floodway or in a floodplain on which a detailed study has not been conducted which drains more than one square mile, then the permit shall be referred to a registered professional engineer (P.E.) under the employ or contract of the Village for review to ensure that the development meets the requirements of Sections 26-303 through 26-307.  In the case of an appropriate use, the P.E. shall state in writing that the development meets the requirements of Sections 26-303 through 26-307.

(C)       Dam Safety Requirements. Ensure that a DWR Dam Safety permit has been issued or a letter indicating no Dam Safety permit is required, if the proposed development activity includes construction of a dam as defined in SubSection 26-302(B). Regulated dams may include weirs, restrictive culverts or impoundment structures.

(D)       Other Permit Requirements. Ensure that any and all required federal, state, county, and local permits are received prior to the issuance of a floodplain development permit.

(E)       Plan Review and Permit Issuance. Ensure that all development activities within the SFHA's of the jurisdiction of the Village meet the requirements of this Chapter and issue a floodplain development permit in accordance with the provisions of this Chapter and other regulations of this community when the development meets the condition of this Chapter.

(F)       Inspection Review. Inspect all development projects before, during, and after construction to assure proper elevation of the structure and to ensure they comply with the provisions of this Chapter.

(G)       Elevation and Floodproofing Certificates. Maintain in the permit files an Elevation Certificate certifying the elevation of the lowest floor (including basement) of a residential or non-residential building or the elevation to which a non-residential building has been floodproofed, using a Floodproofing Certificate, for all buildings subject to Section 26-306 of this Chapter for public inspection and provide copies of same.

(H)       Records for Public Inspection.  Maintain for public inspection and furnish upon request, base flood data, SFHA and regulatory floodway maps, copies of federal or state permit documents, variance documentation, Conditional Letter of Map Revision, Letter of Map Revision, Letter of Map Amendment, and "as-built" elevation and floodproofing or elevation and floodproofing certificates for all buildings constructed subject to this Chapter.

(I)        State Permit. Ensure that construction authorization has been granted by the Illinois Division of Water Resources, for all development projects subject to Sections 26-304 and 26-305 of this Chapter, unless enforcement responsibility has been delegated to the Village.  Upon acceptance of this Chapter by DWR and FEMA, responsibility is hereby delegated to the Village as per 92 Ill.Adm.Code 708 for construction in the regulatory floodway and floodplain when floodways have not been defined in Sections 26-304 and 26-305 of this Chapter.  However, the following review approvals are not delegated to the Village and shall require review or permits from DWR:

(1)        Organizations which are exempt from this Chapter, as per the Illinois Revised Statutes.

(2)        Department of Transportation projects, dams or impoundment structures as defined in SubSection 26-103(B) and all other state federal or local unit of government projects, including projects of the Village and County, except for those projects meeting the requirements of Section 26-304(B)(5).

(3)        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, per Section 26-304(B)(2)(e).

(4)        An engineer's analysis of the flood profile due to Section 26-304(B)(2)(d).

(5)        Alternative transition Sections and hydraulically equivalent compensatory storage as indicated in Section 26-304(B)(2) (a), (b) and (h).

(6)        Permit issuance of structures within or over publicly navigable rivers, lakes, and streams.

(7)        Any changes in the Base Flood Elevation or floodway locations.

(8)        Base Flood Elevation determinations where none now exist.

(J)        Cooperation with Other Agencies. Cooperate with state, county, and federal floodplain management agencies to improve base flood or 100-year frequency flood and floodway data and to improve the administration of this Chapter.  Submit data to DWR and the Federal Emergency Management Agency for proposed revisions of a regulatory map.  Submit reports as required for the National Flood Insurance Program.  Notify the Federal Emergency Management Agency of any proposed amendments to this Chapter.

(K)       Promulgate Regulations. Promulgate rules and regulations as necessary to administer and enforce the provisions of this Chapter, subject however to the review and approval of DWR and FEMA for any chapter changes.

Sec. 26-302.    Base Flood Elevation. [back to top]

This Chapter's protection standard is based on the Flood Insurance Study for the Village.  If a base flood elevation or 100-year frequency flood elevation is not available for a particular site, then the protection standard shall be according to the best existing data available in the Illinois State Water Survey's Floodplain Information Repository.  When a party disagrees with the best available data, he/she may finance the detailed engineering study needed to replace existing data with better data and submit it to DWR, FEMA, and the Village.

(A)       The base flood or 100-year frequency flood elevation for the SFHA's of Salt Creek and Westwood Creek shall be as delineated on the 100-year flood profiles in the Flood Insurance Study of the Village prepared by FEMA and dated January 16, 1987, and such amendments to such study and maps as may be prepared from time to time.

(B)       The base flood or 100-year frequency flood elevation for the SFHA's of those parts of unincorporated DuPage County that are within the extraterritorial jurisdiction of the Village or that may be annexed into the Village shall be as delineated on the 100-year flood profiles in the Flood Insurance Study of DuPage County prepared by FEMA and dated October 15, 1981, and such amendments or revisions to such study and maps as may be prepared from time to time.

(C)       The base flood or 100-year frequency flood elevation for each SFHA delineated as an "AH Zone" or "AO Zone" shall be that elevation (or depth) delineated on the Flood Insurance Rate Map of the Village.

(D)       The base flood or 100-year frequency flood elevation for each of the remaining SFHA's delineated as an "A Zone" on the Flood Insurance Rate Map of the Village shall be according to the best existing data available in the Illinois State Survey Floodplain Information Repository.  When no base flood or 100-frequency flood elevation exists, the base flood or 100-year frequency flood elevation for a Riverine SFHA shall be determined from a backwater model, such as HEC-2, WSP-2, or a dynamic model such as HIP.  The flood flows used in the hydraulic models shall be obtained from a hydrologic model, such as HEC-l TR-20, or HIP, or by techniques presented in various publications prepared by the United States Geological Survey for estimating peak flood discharges.  Flood flows should be based on anticipated future land use conditions in the watershed as determined from adopted local and regional land use plans.  Along any watercourses draining more than one square mile, the above analyses shall be submitted to DWR for approval; once approved, it must be submitted to the Illinois State Water Survey Floodplain Information Repository for filing.  For a non-riverine SFHA, the Base Flood Elevation shall be the historic Flood of Record plus 3 feet, unless calculated by a detailed engineering study and approved by the Illinois State Water Survey.

Sec. 26-303.    Occupation and Use of Flood Fringe Areas. [back to top]

(A)       Development Permit. No person, firm, corporation, or governmental body not exempted by state law shall commence any development in the SFHA without first obtaining a development permit from the Village Engineer.

(1)        Application for a development permit shall be made on a form provided by the Village Engineer.  The application shall be accompanied by drawings of the site, drawn to scale, showing property line dimensions and legal description for the property and sealed by a licensed engineer, architect, or land surveyor; existing grade elevations in M.S.L., 1929 adj. datum or N.G.V.D. and all changes in grade resulting from excavation or filling; the location and dimensions of all buildings and additions to buildings.  For all proposed buildings, the elevation of the lowest floor (including basement) and lowest adjacent grade shall be shown on the submitted plans and the development will be subject to the requirements of Section 26-306 of this Chapter.

(2)        Upon receipt of a development permit application, the Village Engineer shall compare the elevation of the site to the base flood or 100-year frequency flood elevation.  Any development located on land that  can  be  shown  to have been higher than the base flood elevation as of the site's first Flood Insurance Rate Map identification is not in the SFHA and, therefore, not subject to the requirements of this Chapter.  The Village Engineer's office shall maintain documentation of the existing ground elevation at the development site and certification that this ground elevation existed prior to the date of the site's first Flood Insurance Rate Map identification.

(3)        The Village Engineer shall be responsible for obtaining from the applicant, copies of all other local, state, county, and federal permits, approval or permit-not- required letters that may be required for this type of activity.  The Village Engineer may not issue a permit unless all other local, state, and federal permits have been obtained.

(B)       Preventing Increased Damages. No development in the flood fringe shall create a threat to public health and safety.

(1)        If fill is being used to elevate the site above the base flood or 100-year frequency flood elevation, the applicant shall submit sufficient data and obtain a letter of map revision (LOMR) from FEMA for the purpose of removing the site from the floodplain.

(2)        Compensatory Storage.  Whenever any portion of a floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the base flood or 100-year frequency flood elevation shall be compensated for and balanced by one and one-half times the hydraulically equivalent volume of excavation taken from below the base flood or 100-year frequency flood elevation.  The excavation volume shall be at least one and one-half times the volume of storage lost due to the fill or structure.  In the case of streams and watercourses, such excavation shall be made opposite or adjacent to the areas so filled or occupied.  All floodplain storage lost below the existing 10-year flood elevation shall be replaced below the proposed 10-year flood elevation.  All floodplain storage lost above the existing 10-year flood elevation shall be replaced above the proposed 10-year flood elevation.  All such excavations shall be constructed to drain freely and openly to the watercourse.

Sec. 26-304.    Occupation and Use of Identified Floodways. [back to top]

This Section applies to proposed development, redevelopment, site modification, or building modification within a regulatory floodway.  The regulatory floodway for Salt Creek and Westwood Creek shall be as delineated on the regulatory floodway maps designated by DWR according and referenced in Section 26-103.  Only those uses and structures will be permitted which meet the criteria in this Section.  All floodway modifications shall be the minimum necessary to accomplish the purpose of the project. The development shall also meet the requirements of Section 26-306.

(A)       Development Permit. No person, firm, corporation, or governmental body not exempted by state law shall commence any development in a floodway without first obtaining a development permit from the Village Engineer.

(1)        Application for a development permit shall be made on a form provided by the Village Engineer.  The application shall include the following information:

(a)        Name and address of applicant.

(b)        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.

(c)        Name of stream or body of water affected.

(d)        Description of proposed activity.

(e)        Statement of purpose of proposed activity.

(f)         Anticipated dates of initiation and completion of activity.

(g)        Name and mailing address of the owner of the subject property if different from the applicant.

(h)        Signature of applicant or the applicant's agent.

(i)         If the applicant is a corporation, the president or other authorized officer shall sign the application form. 

(j)         If the applicant is a partnership, each partner shall sign the application form.

(k)        If the applicant is a land trust, the trust officer shall sign the name of the trustee by him/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.

(l)         Plans of the proposed activity shall be provided which includes as a minimum:

(i)         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.

(ii)        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 mean sea level (1 29 adjustment) datum or N.G.V.D., adjacent property lines and ownership, drainage and flood control easements, location of any channels and any existing or future access roads, regulatory floodway limit, floodplain limit, specifications and dimensions of any proposed channel modifications, location and orientation of cross-Sections, north arrow, and a graphic or numerical scale.

(iii)       Cross-Section views of the project and engineering study reach showing existing  and proposed conditions including principal dimensions of the work as shown in plan view, existing and proposed elevations, normal water elevation, 100-year frequency flood elevation, and graphic or numerical scales (horizontal and vertical).

(iv)       A copy of the regulatory floodway map, marked to reflect any proposed change in the regulatory floodway location.

(m)       Any and all other local, county, state, and federal permits or approval letters that may be required for this type of development.

(n)        Engineering calculations and supporting data shall be submitted showing that the proposed work will meet the permit criteria of Section 26-304(B).

(o)        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 DWR 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.

(p)        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 professional engineer, licensed architect or 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 Section 26-306 of this Chapter.

(q)        If the proposed project involves a channel modification, the applicant shall submit the following information:

(i)         A discussion of the purpose of and the  need for the proposed work.

(ii)        A discussion of the feasibility of using alternative locations or methods to accomplish the purpose of the proposed work.

(iii)       An analysis of the extent and permanence of the impacts the project would have on  the physical and biological condition of the body of water affected.

(2)        The Village Engineer shall be responsible for obtaining from the applicant copies of all other local, state, and federal permits and approvals that may be required for this type of activity.  The Village Engineer may not issue the development permit unless all required federal and state permits have been obtained.  A Registered Professional Engineer, under the employ or contract of the Village shall review and approve applications reviewed under this Section.

(B)       Preventing Increased Damages and a List of Appropriate Uses.  The only developments in a floodway which will be allowed are Appropriate Uses, which will not cause a rise in the base flood elevation, and which will not create a damaging or potentially damaging increase in flood heights or velocities or be a threat to public health and safety and welfare or impair the natural hydrologic and hydraulic functions of the floodway or channel, or permanently impair existing water quality or aquatic habitat.  Construction impacts shall be minimized by appropriate mitigation methods as called for in this Chapter.  Only those Appropriate Uses listed in 92 Ill.Adm.Code 708 will be allowed.  Appropriate uses do not include the construction or placement of any new structures, fill, building additions, buildings on stilts, excavation or channel modifications done to accommodate otherwise nonappropriate uses in the floodway, fencing (including landscaping or planting design to act as a fence), and storage of materials except as specifically defined above as an Appropriate Use.

(1)        The approved Appropriate Uses are as follows:

(a)        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.

(b)        Structures or facilities relating to the use of, or requiring access to, the water or shoreline, such as pumping and treatment facilities, and facilities and improvements related to recreational boating, commercial shipping, and other functionally water dependent uses.

(c)        Storm and sanitary sewer outfalls.

(d)        Underground and overhead utilities.

(e)        Recreational facilities such as playing fields and trail systems including any related fencing (at least 50 percent open when viewed from any one direction) built parallel to the direction of flood flows, and including open air pavilions.

(f)         Detached garages, storage sheds, or other nonhabitable accessory structures without toilet facilities to existing buildings that will not block flood flows, nor reduce floodway storage.

(g)        Bridge, culverts, roadways, sidewalks, railways, runways and taxiways and any modification thereto. 

(h)        Parking lots and any modifications thereto (where depth of flooding at the 100-year frequency flood event will not exceed l.0 feet) and aircraft parking aprons built at or below ground elevation.

(i)         Regulatory floodway regrading, without fill, to create a positive non-erosive slope toward a watercourse.

(j)         Floodproofing activities to protect previously existing lawful structures including the construction of watertight window wells, elevating structures, or construction of floodwalls around residential, commercial or industrial principal structures where the outside toe of the floodwall shall be no more than 10 feet away from the exterior wall of the existing structure, and which are not considered substantial improvements to the structure.

(k)        In the case of damaged or replacement buildings, reconstruction or repairs made to a building that are valued at less than 50 percent of the market value of the building before it was damaged or replaced, and which do not increase the outside dimensions of the building.

(l)         Additions to existing buildings above the BFE that do not increase the building's foot print and are valued at less than 50 percent of the market value of the building. 

(2)        Within the regulatory floodway, as identified on the regulatory floodway maps designated by DWR, 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 that any structure meets the protection requirements of Section 26-306 of this Chapter.

(a)        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 due to the project will 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:

(i)         Regulatory floodway conveyance,

 "K" = 1.486 AR2/3

    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.  (See Open Channel Hydraulics, Ven Te Chow, 1959, Mc Graw-Hill Book Company, New York.)

(ii)        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.

(iii)       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 DWR through engineering calculations or model tests that more abrupt transitions may be used with the same efficiency:

a.         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 4 feet of the flooded stream's length.

b.         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.

c.         When expanding or contracting flows in a vertical direction, a minimum of one foot vertical transition for every 10 feet of stream length shall be used.

d.         Transition Sections shall be provided between cross-Sections with rapid expansions and contractions and when meeting the regulatory floodway delineation on adjacent properties.

e.         All cross-Sections used in the calculations shall be located perpendicular to flood flows.

(b)        Preservation of Floodway Storage so as Not to In-crease 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 equal to at least l.5 times the volume of floodway 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 10-year flood elevation shall be replaced below the proposed 10-year flood elevation.  All regulatory floodway storage lost above the existing 10-year flood elevation shall be replaced above the proposed 10-year flood elevation.  All such excavations 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, the applicant's engineer shall demonstrate to DWR through a determination of flood discharges and water surface elevations that the compensatory storage is hydraulically equivalent.  Finally, there shall be no reduction in floodway surface area as a result of a floodway modification, unless such modification is necessary to reduce flooding at existing structure.

(c)        Preservation of 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 will not result in more than a ten percent an increase in the average channel or regulatory floodway velocities or stage for all flood events up to and including the 100-year frequency event.  However, 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.

(d)        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 0.l foot when compared to the existing conditions for all flood events up to and including the 100-year frequency event; or the upstream flood stage increases  will  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 0.l feet, the developer must contact DWR, Dam Safety Section for a Dam Safety permit or waiver.

(i)         The engineering analysis of upstream flood stages must be calculated using the flood study flows and corresponding flood elevations for tailwater conditions for the flood study specified in Section 26-302 of this Chapter.  Culverts must be analyzed using the U.S. DOT, FHWA-Hydraulic Chart for the Selection of Highway Culverts.  Bridges must be analyzed using the U.S. DOT/Federal Highway Administration Hydraulics of Bridge Waterways calculation procedures.

(ii)        Lost floodway storage must be compensated for per Section 26-304(B)(2)(b).

(iii)       Velocity increase must be mitigated per Section 26-304(B)(2)(c).

(iv)       If the crossing is proposed over a public water that is used for recreational or commercial navigation, a Department of Transportation permit must be received. 

(v)        The hydraulic analysis for the backwater caused by the bridge showing the existing condition and proposed regulatory profile must be submitted to DWR for concurrence that a CLOMR is not required by Section 26-304(B) (2)(n).

(vi)       All excavations for the construction of the crossing shall be designed per Section 26-304(B).

(e)        Reconstruction or Modification of Existing Bridges, Culverts, and Approach Roads. 

(i)         The bridge or culvert and roadway approach reconstruction or modification shall be constructed with no more than 0.l foot increase in backwater over the existing flood profile for all flood frequencies up to and including the 100-year event, if the existing structure is not a source of flood damage.

(ii)        If the existing bridge or culvert and roadway approach is a source of flood damage to buildings or structures in the upstream floodplain, 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.

(iii)       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 the Department of Transportation Rules 92 Ill.Adm.Code 708 (Floodway Construction in Northeastern Illinois) and submitted to the Division for review and concurrence before a permit is issued.

(f)         On-Stream Structures Built for the Purpose of Backing Up Water.  Any increase in upstream stream flood stages greater than 0.l foot when compared to the existing conditions, for all flood events up to and including the 100-year frequency 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 letter indicating a permit is not required must be obtained from DWR, 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 as defined in Section 26-103(B) shall meet the permitting requirements of 92 Ill. Adm.  Code 702 (Construction and Maintenance of Dams).  If the proposed activity involves a modification of the channel or floodway to accommodate an impoundment, it shall be demonstrated that:

(i)         The impoundment is determined to be in the public interest by providing flood control, public recreation, or regional storm water detention.

(ii)        The impoundment will not prevent the migration of indigenous fish species, which require access to upstream areas as part of their life cycle, such as for spawning.

(iii)       The impoundment will not cause or contribute to degraded water quality or habitat conditions.  Impoundment design should include gradual bank slopes, appropriate bank stabilization measures, and a presedimentation basin.

(iv)       A non-point source control plan has been implemented in the upstream watershed to control the effects of sediment runoff as well as minimize the input of nutrients, oil and grease, metals, and other pollutants.  If there is more than one municipality in the upstream watershed, the municipality in which the impoundment is constructed should coordinate with upstream municipalities to ensure comprehensive watershed control.

(v)        The project otherwise complies with the requirement of Section 26-304.

(g)        Floodproofing of Existing Habitable, Residential and Commercial Structures.  If construction is required beyond the outside dimensions of the existing building, the outside perimeter of the floodproofing construction shall be placed no further than 10 feet from the outside of the building.  Compensation of lost storage and conveyance will not be required for floodproofing activities.

(h)        Excavation in the Floodway.  When excavation is proposed in the design of bridges and culvert openings, including 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 DWR through engineering calculations or model tests that more abrupt transitions may be used with the same efficiency.

(i)         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 4 feet of the flooded stream's length.

(ii)        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.

(iii)       When expanding or contracting flows in a vertical direction, a minimum of one foot vertical transition for every 10 feet of stream length shall be used.

(iv)       Erosion/scour protection shall be provided inland upstream and downstream of the transition Sections.

(i)         If the proposed activity involves a channel modification, it shall be demonstrated that:

(i)         There are no practicable alternatives to the  activity which would accomplish its purpose with less impact to the natural conditions of the body of water affected.

(ii)        The activity has been planned and designed and will be constructed in a way which will minimize its adverse impacts on the natural conditions of the body of water affected, consistent with the following criteria:

a.         The physical characteristics of the modified channel shall match as closely as possible those of the existing channel in length, cross-Section, slope and sinuosity.

b.         Hydraulically effective transitions shall be provided at both the upstream and downstream ends of the project, designed such that they will prevent erosion.

c.         One-sided construction of a channel shall be used when feasible.  Removal of streamside (riparian) vegetation should be limited to one side of the channel, where possible, to preserve the shading and stabilization effects of the vegetation.

d.         Clearing of vegetation shall be limited to that which is essential for construction of the channel.

e.         Channel banks shall be constructed with a side slope of no steeper than 4:l horizontal to vertical, wherever practicable.  Natural vegetation and gradual side slopes are the preferred method for bank stabilization.  Where high velocities or sharp bends necessitate the use of alternative stabilization measures, natural rock or riprap are preferred materials. Artificial materials such as concrete, gabion, or construction rubble should be avoided unless there are no practicable alternatives.

f.          All disturbed areas associated with the modification shall be seeded or otherwise stabilized as soon as possible upon completion of construction.  Erosion blanket or an equivalent material shall be required to stabilize disturbed channel banks prior to establishment of the vegetative cover.

g.         If the existing channel contains considerable bottom diversity such as deep pools, riffles, and other similar features, such features shall be pro-vided in the new channel.  Spawning and nesting areas and flow characteristics compatible with fish habitat shall also be established where appropriate.

h.         The project otherwise complies with the requirements of Section 26-304.

(j)         Seeding and Stabilization Plan.  For all activities located in a floodway, a seeding and stabilization plan shall be submitted by the applicant.

(k)        Soil Erosion and Sedimentation Measures.  For all activities in the floodway, including grading, filling, and excavation, in which there is potential for erosion of exposed soil, soil erosion, and sedimentation, control measures shall be employed consistent with the following criteria:

(i)         The construction area shall be minimized to preserve the maximum vegetation possible.  Construction shall be scheduled to minimize the time soil is exposed and unprotected.  In no case shall the existing natural vegetation be destroyed, removed, or disturbed more than 15 days prior to the initiation of improvements.

(ii)        Temporary and/or permanent soil stabilization shall be applied to denuded areas as soon as possible.  As a minimum, soil stabilization shall be provided within 15 days after final grade is reached on any portion of the site, and within 15 days to denuded areas which may not be at final grade but will remain undisturbed for longer than 60 days.

(iii)       Sedimentation control measures shall be installed before any significant grading or  filling is initiated on the site to prevent  the movement of eroded sediments off-site or into the channel.  Potential sediment control devices include filter fences, straw bale fences, check dams, diversion ditches, and sediment basins.

(iv)       A vegetated buffer strip of at least 25 feet in width shall be preserved and/or re- established, where possible, along exiting channels (see Section 26-304(B)(2)(p).  Construction vehicle use of channels shall be minimized.  Temporary stream crossings shall be constructed, where necessary, to minimize erosion.  Necessary construction in or along channels shall be restabilized immediately.

(v)        Soil erosion and sedimentation control measures shall be designed and implemented consistent with "Procedures and Standards for Urban Soil Erosion and Sedimentation Control in Illinois" (1988) also known as the "Green Book" and "Standards and Specifications for Soil Erosion and Sediment Control" (EPA, 1987).

(l)         Public Flood Control Projects.  For public flood control projects, the permitting requirements of this Section will be considered met if the applicant can demonstrate to DWR through hydraulic and hydrologic calculations that the proposed project will 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.

(m)       General Criteria for Analysis of Flood Elevations. 

(i)         The flood profiles, flows, and floodway data in the regulatory floodway study, referenced in Section 26-302, must be used for analysis of the base conditions.  If the study data appears to be in error or conditions have changed, DWR shall be contacted for approval and concurrence on the appropriate base conditions data to use.

(ii)        If the 100-year regulatory floodway 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 Section for the 100-year frequency flood elevations of the regulatory floodway conditions and conditions with the receiving stream at normal water elevations.

(iii)       If the applicant learns from DWR, local governments, or a private owner that a downstream restrictive bridge or culvert is scheduled to be removed, reconstructed, 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 Section for both the existing conditions and the expected flood profile conditions when the bridge, culvert or flood control project is built.

(n)        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 DWR and to FEMA all the information, calculations and documents necessary to be issued a conditional regulatory floodway map revision and receive from DWR a conditional approval of the regulatory floodway change before a permit is issued.  However, the final regulatory floodway map will not be changed by DWR until as-built plans or record drawings are submitted and accepted by FEMA and DWR.  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 DWR 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 (LOMR) is issued by FEMA and DWR.

(o)        Professional Engineer's Supervision.  All engineering analyses shall be performed by or under the supervision of a registered professional engineer.

(p)        For all activities in the floodway involving construction within 25 feet of the channel, the following criteria shall be met:

(i)         A natural vegetation buffer strip shall be preserved within at least 25 feet of the ordinary high water mark of the channel. 

(ii)        Where it is impossible to protect this buffer strip during the construction of an Appropriate Use, a vegetated buffer strip shall be established upon completion of construction.

(iii)       The use of native riparian vegetation is preferred in the buffer strip.  Access through this buffer strip shall be provided, when necessary, for stream maintenance purposes.

(q)        After receipt of conditional approval of the regulatory floodway change and issuance of a permit and a Conditional Letter of Map Revision, construction as necessary to change the regulatory floodway designation may proceed but 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 will be revised upon acceptance and concurrence by DWR and FEMA of the "as built" plans.

(3)        State Review.  For those projects listed below located in a regulatory floodway, the following criteria shall be submitted to DWR for their review and concurrence prior to the issuance of a permit:

(a)        DWR will review an engineer's analysis of the flood profile due to a proposed bridge pursuant to Section 26-304(B)(2)(d).

(b)        DWR will review an engineer's determination that an existing bridge or culvert crossing is not a source of flood damage and the analysis shall indicate the proposed flood profile, pursuant to Section 26-304(B)(2)(e).

(c)        The DWR will review alternative transition Sections and hydraulically equivalent storage pursuant to Section 26-304(B)(2)(a), (b), and (h).

(d)        The DWR will review and approve prior to the start of construction any Department projects, dams (as defined in Section 26-103), and all other state, federal or local units of government projects, including projects of the municipality or county.

(4)        Other Permits.  In addition to the other requirements of this Chapter, a development permit for a site located in a floodway shall not be issued unless the applicant first obtains a permit or written documentation that a permit is not required from DWR, issued pursuant to 615 ILCS 5/5 et seq.  No permit from DWR shall be required if the Division has delegated this responsibility to the Village.

(5)        Dam Safety Permits.  Any work involving the construction, modification or removal of a dam as defined in Section 26-103 per 92 Ill.Adm.Code 702 (Rules for Construction of Dams) shall obtain an Illinois Division of Water Resources Dam Safety permit prior to the start of construction of a dam.  If the Village Engineer finds a dam that does not have a DWR permit, he/she shall immediately notify the Dam Safety Section of the Division of Water Resources.  If the Village Engineer finds a dam which is believed to be in unsafe condition, he/she shall immediately notify the owner of the dam, DWR, Dam Safety Section in Springfield, and the Illinois Emergency Services and Disaster Agency (ESDA).

(6)        Activities that do not require a registered professional engineer's review.  The following activities may be permitted without a registered professional engineer's review.  Such activities shall still meet the other requirement of this Chapter, including the mitigation requirements.

(a)        Underground and overhead utilities that:

(i)         Do not result in any increase in existing ground elevations, or

(ii)        Do not require the placement of above ground structures in the floodway, or

(iii)       In the case of underground stream crossings, the top of the pipe or encasement is buried a minimum of 3 feet below the existing stream bed, and

(iv)       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.

(b)        Storm and sanitary sewer outfalls that:

(i)         Do not extend riverward or lakeward of the existing adjacent natural bank slope, and

(ii)        Do not result in an increase in ground elevation, and

(iii)       Are designed so as not to cause stream erosion at the outfall location.

(c)        Construction of sidewalks, athletic fields (excluding fences), properly anchored playground equipment and patios at grade.

(d)        Construction of shoreline and streambank protection that:

(i)         Does not exceed l,000 feet in length.

(ii)        Materials are not placed higher than the existing top of bank.

(iii)       Materials are placed so as not to reduce the cross-sectional area of the stream channel or bank of the lake.

(iv)       Vegetative stabilization and gradual side slopes are the preferred mitigation methods for existing erosion problems.  Where high channel velocities, sharp bends or wave action necessitate the use of alternative stabilization measures, natural rock or rip-rap are preferred materials.  Artificial materials such as concrete, construction rubble, and gabions should be avoided unless there are no practicable alternatives.

(e)        Temporary stream crossings in which:

(i)         The approach roads will be 0.5 feet (l/2-foot) or less above natural grade.

(ii)        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.

(iii)       The top of the roadway fill in the channel will be at lest 2 feet below the top of the lowest bank.  All fill in the channel shall be non-erosive materials, such as riprap or gravel.

(iv)       All disturbed stream banks will be seeded or otherwise stabilized as soon as possible upon installation and again upon removal of the crossing.

(v)        The access road and temporary crossings will be removed within one year after authorization.

Sec. 26-305.    Occupation and Use of SFHA Areas where Floodways Are Not Identified. [back to top]

In SFHA or floodplains, where no floodways have been identified and no base flood or 100-year frequency flood elevations have been established by FEMA, and draining more than a square mile, no development shall be permitted unless the cumulative effect of the proposals, when combined with all other existing and anticipated uses and structures, shall not significantly impede or increase the flow and passage of the floodwaters nor significantly increase the base flood or 100-year frequency flood elevation.

(A)       Development Permit.  No person, firm, corporation, or governmental body, not exempted by state law, shall commence any development in a SFHA or floodplain without first obtaining a development permit from the Village Engineer.  Application for a development permit shall be made on a form provided by the Village Engineer.  The application shall be accompanied by drawings of the site, drawn to scale showing property line dimensions;  and existing grade elevations and all changes in grade resulting from excavation or filling, sealed by a licensed engineer, architect, or surveyor; the location and dimensions of all buildings and additions to buildings; and the elevation at the lowest floor (including basement) of all proposed buildings subject to the requirements of Section 26-306 of this Chapter.

(1)        The application for a development permit shall also include the following information:

(a)        A detailed description of the proposed activity, its purpose, and intended use.

(b)        Site location (including legal description) of the property, drawn to scale, on the regulatory floodway maps, indicating whether it is proposed to be in an incorporated or unincorporated area.

(c)        Anticipated dates of initiation and completion of activity.

(d)        Plans of the proposed activity shall be provided which include as a minimum:

(i)         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.

(ii)        A plan review of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the structure or work, elevations in mean sea level (1929 adjustment) datum or N.G.V.D., adjacent property lines and ownership, drainage and flood control easements, floodplain limit, location and orientation of crosssections, north arrow, and a graphical or numerical scale.

(iii)       Cross-section view of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the work as shown in plan view, existing and proposed elevations, normal water elevations, 10-year frequency flood elevation,  100-year frequency flood elevation, and graphical or numerical scales (horizontal and vertical).

(e)        Engineering calculations and supporting data shall be submitted showing that the proposed work will meet the criteria of Section 26-305(B).

(f)         Any and all other local, state and federal permits or approval that may be required for this type of development.

(2)        Based on the best available existing data according to the Illinois State Water Survey's Floodplain Information Repository, the Village Engineer shall compare the elevation of the site to the base flood or 100-year frequency flood elevation.  Should no elevation information exist for the site, the developer's engineer shall calculate the elevation according to Section 26-302.  Any development located on land that can be shown to have been higher than the base flood elevation as of the site's first Flood Insurance Rate Map Identification is not in the SFHA and, therefore, is not subject to the requirements of this Chapter.  The Building Department shall maintain documentation of the existing ground elevation at the development site and certification that this ground elevation existed prior to the date of the site's first Flood Insurance Rate map identification.

(3)        The Village Engineer shall be responsible for obtaining from the applicant copies of all other local, state, and federal permits, approvals or permit-not-required letters that may be required for this type of activity.  The Village Engineer shall not issue the development permit unless all required local, state, and federal permits have been obtained.

(B)       Preventing Increased Damages. No development in the SFHA, where a floodway has not been determined shall create a damaging or potentially damaging increase in flood heights or velocities or threat to public health, safety, and welfare or impair the natural hydrologic and hydraulic functions of the floodway or channel.

(1)        Within all riverine SFHA's where the floodway has not been determined, the following standards shall apply:

(a)        The developer shall have a Registered Professional Engineer state in writing and show through supporting plans, calculations, and data that the project meets the engineering requirements of Section 26-304(B) (2) for the entire floodplain, as calculated under the provisions of Section 26-302(D) of this Chapter.  As an alternative, the developer should have an engineering study performed to determine a floodway and submit that engineering study to DWR for acceptance as a regulatory floodway.  Upon acceptance of their floodway by the Department, the developer shall then demonstrate that the project meets the requirements of Section 26-304 for the regulatory floodway.  The floodway shall be defined according to the definition in Section 2-106(B) of this Chapter.

(b)        A development permit shall not be issued unless the applicant first obtains a permit from DWR or written documentation that a permit is not required from DWR.

(c)        No permit from DWR shall be required if the Division has delegated permit responsibility to the Village per 92 Ill. Adm. Code, Part 708 for regulatory floodways, per DWR Statewide Permit entitled "Construction in Floodplains with No Designated Floodways in Northeastern Illinois."

(d)        Dam Safety Permits.  Any work involving the construction, modification or removal of a dam or an on-stream structure to impound water as defined in Section 26103(B) shall obtain an Illinois Division of Water Resources Dam Safety permit or letter indicating a permit is not required prior to the start of construction of a dam.  If the Village Engineer finds a dam that does not have a DWR permit, he shall immediately notify the Dam Safety Section of the Division of Water Resources.  If the Village Engineer finds a dam which is believed to be in unsafe condition, he shall immediately notify the owner of the dam, the Illinois Emergency Services and Disaster Agency (ESDA), and the DWR, Dam Safety Section in Springfield. 

(e)        The following activities may be permitted without a Registered Professional Engineer's review or calculation of a base flood elevation and regulatory floodway.  Such activities shall still meet the other requirements of this Chapter:

(i)         Underground and overhead utilities that:

a.         Do not result in any increase in existing ground elevations, or

b.         Do not require the placement of above-ground structures in the floodway, or

c.         In the case of underground stream crossings, the top of the pipe or encasement is buried a minimum of 3 feet below the existing streambed, and

d.         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.

(ii)        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.

c.         Are designed so as not to cause stream bank erosion at the outfall location.

(iii)       Construction of shoreline and streambed protection that:

a.         Does not exceed l,000 feet in length or 2 cubic yards per lineal foot of streambed.

b.         Materials are not placed higher than the existing top of bank.

c.         Materials are placed so as not to reduce the cross-sectional area of the stream channel by more than 10 percent.

d.         Vegetative stabilization and gradual side slopes are the preferred mitigation methods for existing erosion problems.  Where high channel velocities, sharp bends or wave action necessitate the use of alternative stabilization measures, natural rock or riprap are preferred materials.  Artificial materials, such as concrete, construction rubble, and gabions should be avoids unless there are no practical alternatives.

(iv)       Temporary stream crossings in which:

a.         The approach will be 0.5 feet (l/2 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 2 feet below the top of the lowest bank.  Any fill in the channel shall be non-erosive materials, such as riprap or gravel.

d.         All disturbed stream banks will be seeded or otherwise stabilized as soon as possible upon installation and again upon removal of construction.

e.         The access road and temporary crossings will be removed within one year after authorization.

(v)        The construction of light poles, sign posts, and similar structures.

(vi)       The construction of sidewalks, drive-ways, athletic fields (excluding fences), patios and similar surfaces which are built at grade.

(vii)      The construction of properly anchored, unwalled, open structures such as playground equipment, pavilions, and carports built at or below existing grade that would not obstruct the flow of flood waters.

(viii)      The placement of properly anchored buildings not exceeding 70 square feet in size nor 10 feet in any one dimension (e.g., animal shelters and tool sheds).

(ix)       The construction of additions to existing buildings which do not increase the first floor area by more than 20 percent, which are located on the upstream or downstream side of the existing building, and which do not extend beyond the sides of the existing building that are parallel to the flow of flood waters.

(x)        Minor maintenance dredging of a stream channel where:

a.         The affected length of stream is less than l,000 feet.

b.         The work is confined to re-establishing flows in natural stream channels.

c.         The cross-sectional area of the dredged channel conforms to that of the natural channel upstream and downstream of the site.

(f)         The flood carrying capacity within any altered or relocated watercourse shall be maintained.

(2)        Compensatory Storage.  Whenever any portion of a floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the base flood or 100-year frequency flood elevation shall be compensated for and balanced by a hydraulically equivalent volume of excavation taken from below the base flood or 100-year frequency flood elevation.  The excavation volume shall be at least equal to one and one half (1-1/2) times the volume of storage that is lost due to the fill or structure.  In the case of streams and watercourses, such excavation shall be made opposite or adjacent to the areas so filled or occupied.  All floodplain storage lost below the existing 10-year flood elevation shall be replaced below the proposed 10-year flood elevation.  All floodplain storage lost above the existing 10-year flood elevation shall be replaced above the proposed 10-year flood elevation.  All such excavations shall be constructed to drain freely and openly to the watercourse.

Sec. 26-306.    Permitting Requirements Applicable to all Flood Plain Areas. [back to top]

In addition to the requirements found in Sections 26-303,  26-304, and 26-305 for development in flood fringes, regulatory floodways, and SFHA or floodplains where no floodways have been identified (Zones A, AO, AH, AE, A1-A30, A99, VO, V1-30, VE, V, M, or E), the following requirements shall be met:

(A)       Public Health Standards

(1)        No developments in the SFHA shall include locating or storing chemicals, explosives, buoyant materials, animal wastes, fertilizers, flammable liquids, pollutants, or other hazardous or toxic materials below the FPE.

(2)        New and replacement water supply systems, wells, sanitary sewer lines and on-site waste disposal systems may be permitted providing all manholes or other above ground openings located below the FPE are watertight.

(B)       Carrying Capacity and Notification. For all projects involving channel modifications, fill, or stream maintenance (including levees), the flood carrying capacity of the water course shall be maintained.  In addition, the Village shall notify adjacent communities in writing 30 day prior to the issuance of a permit for the alteration or relocation of the watercourse.

(C)       Protecting Buildings. All buildings located within a 100-year floodplain, also known as a SFHA, shall be protected from flood damage below the flood protection elevation.  However, existing buildings located within a regulatory floodway shall also meet the more restrictive Appropriate Use Standards included in Section 26-304. 

(1)        The building criteria apply to the following situations:

(a)        Construction or placement of a new building.

(b)        A structural alteration to an existing building that either increases the first floor area by more than 20 percent or the building's market value by more than 50 percent.

(c)        Installing a manufactured home on a new site or a new manufactured home on an existing site.  This building protection requirement does not apply to returning a mobile home to the same site it lawfully occupied before it was removed to avoid flood damage.

(d)        Installing a travel trailer on a site for more than 180 days.

(2)        This building protection requirement may be met by one of the following methods.

(a)        A residential or non-residential building, when allowed, may be constructed on permanent landfill in accordance with the following:

(i)         The lowest floor (including basement) shall be at or above the flood protection elevation.

(ii)        The fill shall be placed in layers no greater than l-foot deep before compaction and should extend at least 10 feet beyond the foundation of the building before sloping below the flood protection elevation.  The top of the fill shall be above the flood protection elevation.  However, the 10-foot minimum may be waived if a structural engineer certifies an alternative method to protect the building from damages due to hydrostatic pressures.  The fill shall be protected against erosion and scour.  The fill shall not adversely affect the flow of surface drainage from or onto neighboring properties.

(b)        A residential or non-residential building may be elevated in accordance with the following: 

(i)         The building or improvement shall be elevated on crawl space, stilts, piles, walls, or other foundation that is permanently open to flood waters and not subject to damage by hydrostatic pressures of the base flood or 100-year frequency flood.  The permanent openings shall be no more than one foot above grade, and consist of a minimum of two openings.  The openings must have 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.

(ii)        The foundation and supporting members shall be anchored and aligned in relation to flood flows and adjoining structures so as to minimize exposure to known hydrodynamic forces such as current, waves, ice, and floating debris.

(iii)       All areas below the flood protection elevation shall be constructed of materials resistant to flood damage.  The lowest floor (including basement) and all electrical, heating, ventilating, plumbing, and air conditioning equipment and utility meters shall be located at or above the flood protection elevation.  Water and sewer pipes, electrical and telephone lines, submersible pumps, and other water-proofed service facilities may be located below the flood protection elevation.

(iv)       No area below the flood protection elevation  shall be used for storage of items or materials.

(v)        Manufactured homes and travel trailers to be installed on a site for more than 180 days shall be elevated to or above the flood protection elevation and shall be 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.

(c)        Only a non-residential building may be structurally floodproofed (in lieu of elevation) provided that a registered professional engineer shall certify that the building has been structurally dry floodproofed below the flood protection elevation, the structure and attendant utility facilities are watertight and capable of resisting the effects of the base flood or 100-year frequency flood.  The building design shall take into account flood velocities, duration, rate of rise, hydrostatic and hydrodynamic forces, the effects of buoyancy, and impacts from debris or ice.  Floodproofing measures shall be operable without human intervention and without an outside source of electricity (levees, berms, floodwalls, and similar works are not considered floodproofing for the purpose of this subsection).

(d)        Non-conforming structures located in a regulatory floodway may remain in use, but may not be enlarged, replaced or structurally altered.  A nonconforming structure damaged by flood, fire, wind or other natural or man-made disaster may be restored unless the damage exceeds 50 percent of its market value before it was damaged, in which case it shall conform to this Chapter.

(3)        Detached garages of single-family homes may be "wet- proofed" provided that all of the following conditions apply:

(a)        The garages are not located in the floodway.

(b)        The garages are only used for the storage of vehicles and tools.

(c)        The garages are not habitable and do not contain other rooms or uses (such as a shop, greenhouse, bedroom, etc.

(d)        All the utilities are above the base flood elevation.

(e)        All the materials that are located below the base flood elevation are flood-resistant.

(f)         The garages cover less than 500 square feet of land.

Sec. 26-307.    Other Development Requirements. [back to top]

The Board of Trustees shall take into account flood hazards to the extent that they are known in all official actions related to land management, use, and development.

(A)       New subdivisions, manufactured home parks, annexation agreements, and Planned Unit Developments (PUD's) within the SFHA shall be reviewed to assure that the proposed developments are consistent with Sections 26-303, 26-304, 26-305, and 26-306 of this Chapter and the need to minimize flood damage.  Plats or plans for new subdivisions, mobile home parks, and PUD's shall include a signed statement by a Registered Professional Engineer that the plat or plans account for changes in the drainage of surface waters in accordance with the Plat Act (765 ILCS 205/2).

(B)       Proposals for new subdivisions, manufactured home parks, travel trailer parks, and PUD's additions to manufactured home parks, and additions to subdivisions shall include base flood or 100-year frequency flood elevation data and floodway delineations.  Where this information is not available from an existing study filed with the Illinois State Water Survey, the applicant's engineer shall be responsible for calculating the base flood or 100-year frequency flood elevation per Section 26-302(D) and the floodway delineation per the definition in Section 26-103(B) and submitting it to the State Water Survey and DWR for review and approval as best available regulatory data.

(C)       Street, 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.

(D)       The Board of Trustees shall not approve any PUD or plat of subdivision located outside the corporate limits unless such agreement or plat is in accordance with the provisions of this Chapter.

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