A. In SFHAs or floodplains (including AE, AH, AO and unnumbered A zones) 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.
1. Watershed Management Permit:
a. No person, firm, corporation, or governmental body, not exempted by state law, shall commence any development in an SFHA or floodplain without first obtaining a watershed management permit from the building officer.
b. Application for a watershed management permit shall be made on a form provided by the building officer. (Ord. 2015-1061, 3-19-2015)
(1) 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 elevations of the lowest floor (including basement) of all proposed buildings subject to the requirements of section 12-1-9 of this chapter. (Ord. 2007-832, 9-5-2007)
(2) The application for a watershed management permit shall also include the following information: (Ord. 2015-1061, 3-19-2015)
(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 designated 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 view of the project and engineering study reach showing existing and proposed conditions including principal dimensions of the structure or work, elevations, using the North American vertical datum of 1988, adjacent property lines and ownership, drainage and flood control easements, distance between proposed activity and navigation channel (when the proposed construction is in or near a commercially navigable body of water), floodplain limit, location and orientation of cross sections, north arrow, and a graphical or numerical scale;
(iii) Cross section views of the project perpendicular to the flow of floodwater 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, 10-year frequency flood elevation, 100-year frequency flood elevation, and graphical or numerical scales (horizontal and vertical); and
(iv) A soil erosion and sedimentation control plan for disturbed areas. This plan shall include a description of the sequence of grading activities and the temporary sediment and erosion control measures to be implemented to mitigate their effects. This plan shall also include a description of final stabilization and revegetation measures, and the identification of a responsible party to ensure postconstruction maintenance.
(3) Engineering calculations and supporting data shall be submitted showing that the proposed work will meet the criteria of subsection A2 of this section. (Ord. 2007-832, 9-5-2007)
(4) Other applicable requirements of article 3 of the WMO.
(5) Any and all other federal, state, and local permits or approvals that may be required for this type of development. (Ord. 2015-1061, 3-19-2015)
c. Based on the best available existing data according to federal, state or other sources, the building officer shall compare the elevation of the site to the base flood or 100-year frequency flood elevation.
(1) Should no elevation information exist for the site, the developer's engineer shall calculate the elevation according to subsection 12-1-5E of this chapter.
(2) Any development located on land that can be shown to have been higher than the base flood elevation of the current flood insurance rate map identification is not in the SFHA and, therefore, not subject to the requirements of this chapter.
(3) The building officer 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.
(4) The building officer shall be responsible for obtaining from the applicant copies of all other federal, state, and local permits, approvals or waivers that may be required for this type of activity. The building officer shall not issue the watershed management permit unless all required federal, state, and local permits have been obtained. (Ord. 2015-1096, 11-12-2015)
2. Preventing Increased Damages:
a. Development Not To Create Damaging Increase In Flood Heights Or Velocity: No development in the SFHA where a floodway has not been determined shall create a damaging or potentially damaging increase in flood heights or velocity or threat to public health, safety and welfare or impair the natural hydrologic and hydraulic functions of the floodway or channel, or impair existing water quality or aquatic habitat. Construction impacts shall be minimized by appropriate mitigation methods as called for in this chapter.
b. Standards: Within all riverine SFHAs where the floodway has not been determined, the following standards shall apply:
(1) Project To Meet Engineering Requirements: 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 subsections 12-1-7B3a through B3i of this chapter for the entire floodplain as calculated under the provisions of subsection 12-1-5E of this chapter.
(A) As an alternative, the developer should have an engineering study performed to determine a floodway and submit that engineering study to IDNR/OWR and FEMA for acceptance as a designated floodway.
(B) Upon acceptance of the floodway by IDNR/OWR and FEMA, the developer shall then demonstrate that the project meets the requirements of section 12-1-7 of this chapter of the designated floodway. The "floodway" shall be defined according to the definition in section 12-1-2 of this chapter. (Ord. 2007-832, 9-5-2007)
(2) IDNR/OWR Permit: A watershed management permit shall not be issued unless the applicant first obtains an IDNR/OWR permit or a determination has been made that an IDNR/OWR permit is not required. (Ord. 2015-1061, 3-19-2015)
(3) Permits For Dams:
(A) Any work involving the construction, modification or removal of a "dam" as defined in section 12-1-2 of this chapter per 17 Illinois administrative code part 3702 (rules for construction of dams) shall obtain an IDNR/OWR permit prior to the start of construction of a dam.
(B) If the building officer finds a dam that does not have an IDNR/OWR permit, the building officer shall immediately notify the IDNR/OWR Bartlett office.
(C) If the building officer finds a dam which is believed to be in unsafe condition, the building officer shall immediately notify the owner of the dam, the IDNR/OWR Bartlett office, and the Illinois emergency management agency (IEMA).
c. Permitted Activities: The following activities may be permitted without a registered professional engineer's review or calculation of base flood elevation and designated floodway. Such activities shall still meet the other requirements of this chapter.
(1) Bridge and culvert crossings of streams in rural areas meeting conditions of IDNR/OWR statewide permit 2;
(2) Barge fleeting facilities meeting conditions of IDNR/OWR statewide permit 3;
(3) Aerial utility crossings meeting conditions of IDNR/OWR statewide permit 4;
(4) Minor boat docks meeting conditions of IDNR/OWR statewide permit 5;
(5) Minor, nonobstructive activities meeting conditions of IDNR/OWR statewide permit 6; activities not involving fill or positive change in grade are covered by this permit;
(6) Outfall structures and drainage ditch outlets meeting conditions of IDNR/OWR statewide permit 7;
(7) Underground pipeline and utility crossings meeting the conditions of IDNR/OWR statewide permit 8;
(8) Bank stabilization projects meeting the conditions of IDNR/OWR statewide permit 9;
(9) Accessory structures and additions to existing residential buildings meeting the conditions of IDNR/OWR statewide permit 10;
(10) Minor maintenance dredging activities meeting conditions of IDNR/OWR statewide permit 11;
(11) Bridge and culvert replacement structures and bridge widenings meeting conditions of IDNR/OWR statewide permit 12;
(12) Temporary construction activities meeting conditions of IDNR/OWR statewide permit 13;
(13) Special uses of public waters meeting conditions of IDNR/OWR statewide permit 14; and
(14) Any development determined by IDNR/OWR to be located entirely within a flood fringe area shall be exempt from state floodway permit requirements.
d. Flood Carrying Capacity Maintained: The flood carrying capacity of any altered or relocated watercourse shall be maintained.
e. Compensatory Storage:
(1) 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.
(2) The excavation volume shall be at least equal to 1.5 times the volume of storage lost due to the fill or structure.
(3) In the case of streams and watercourses, such excavation shall be made opposite or adjacent to the areas so filled or occupied.
(4) 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. (Ord. 2007-832, 9-5-2007)