§ 151.147  REGULATORY FLOODPLAIN, REGULATORY FLOODWAY, FLOOD TABLE LAND AND FLOOD-PRONE AREAS.
   (A)   Applicability.  This section shall apply to all man-made changes to improved or unimproved real estate lying in the regulatory floodplain, the regulatory floodway or on flood table land and flood-prone area, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation, or drilling operations. This section shall not apply to normal maintenance activities undertaken on existing structures and facilities.
   (B)   Regulatory floodplain.
      (1)   Determination and delineation.  The elevation and location of the regulatory floodplain shall be determined as follows.
 
COMMENTARY:
Current Federal Emergency Management Agency maps can be obtained from the Planning, Building and Development Department or online (http://maps.lakecountyil.gov/mapsonline).
 
         (a)   The regulatory floodplain is delineated within a development by projecting the base flood elevation onto the best available topographic information.
         (b)   The base flood elevation shall be obtained from the 100-year flood profiles, as indicated in the floodplain studies listed below:
            1.   Lake County Stormwater Management Commission regulatory floodplain profiles;
            2.   Should no Lake County Stormwater Management Commission-approved regulatory floodplain profile exist for the subject site, the “Flood Insurance Study, County of Lake, Illinois, Unincorporated Areas”, including all flood profiles and elevations contained therein, published by the Federal Emergency Management Agency, including the Federal Insurance Rate Map (see Appendix M, as may be amended by FEMA);
            3.   In the case of Federal Emergency Management Agency-delineated “AH Zones”, the elevation noted on the map shall be the base flood elevation. In the case of Federal Emergency Management Agency-delineated “AO Zones”, the base flood elevation shall be the depth number shown on the map added to the highest adjacent grade, or at least two feet above the highest adjacent grade if no depth number is provided; or
            4.   When no base flood elevation information exists, the base flood elevation shall be determined by a registered professional engineer using an appropriate model or technique as approved by the Lake County Stormwater Management Commission or Illinois Department of Natural Resources, Office of Water Resources. For riverine flood-prone areas with greater than 100 acres of tributary drainage area, non-riverine flood-prone areas with greater than 20 acres of tributary drainage area, and all mapped Special Flood Hazard Areas regardless of drainage area, the base flood elevation determination shall be submitted to the Lake County Stormwater Management Commission for approval prior to issuance of a watershed development permit. The base flood elevation determination for non-riverine depressional floodplains with less than 20 acres of tributary drainage area shall be reviewed and approved by the Planning, Building and Development Director. Base flood elevation determinations shall be based on the critical duration event.
               a.   Where a linear water body has a tributary drainage area of 640 acres or more, the above analyses shall be submitted to the Lake County Stormwater Management Commission for approval by the Illinois Department of Natural Resources, Office of Water Resources.
               b.   For a non-riverine regulatory floodplain, the historic flood of record (as determined by the Planning, Building and Development Director according to subsection (B)(1)(b)4. above plus three feet), may be used for the base flood elevation instead of performing a detailed hydrologic and hydraulic study. However, a detailed hydrologic and hydraulic study may result in a lower base flood elevation.
               c.   Nothing contained herein shall prohibit the application of these regulations to land that can be demonstrated by engineering survey to lie within any regulatory floodplain. Conversely, any lands (except for those located in a regulatory floodway) that can be demonstrated by a topographic survey certified by a registered professional engineer or registered land surveyor to lie beyond the regulatory floodplain, and to the satisfaction of the Planning, Building and Development Director, to have been higher than the base flood elevation as of the date of the first floodplain mapping denoting the site to be in a Special Flood Hazard Area and as of the date of the current effective map shall not be considered to be located in the SFHA.
      (2)   Permitted uses.
         (a)   Only those uses listed in § 151.148 are permitted by right within a regulatory floodplain regardless of the regulations of any zoning district. All uses permitted by § 151.148 are permitted subject to compliance with the all applicable performance standards of § 151.149.
         (b)   All other structures and uses that are permitted by the underlying zoning district but are not listed in § 151.148 may be permitted in the regulatory floodplain only pursuant to § 151.148(B).
         (c)   Nothing herein shall prevent the rebuilding or extension of any existing structures permitted by the underlying zoning district, provided that the rebuilding or extension complies with all applicable performance standards of § 151.149.
      (3)   Additional application requirements.  In addition to other submittal requirements, all of the following additional information shall be provided for all development in the regulatory floodplain:
         (a)   Site location of the property, drawn to scale on the regulatory floodplain map;
         (b)   Plans, cross-sections and profiles of the project showing all of the following:
            1.   The regulatory floodplain limit, including if applicable, the navigation channels for work in public bodies of water as defined by the Illinois Department of Natural Resources, Office of Water Resources;
            2.   Cross-section views of the project for the impacted reach showing existing and proposed conditions including principal dimensions of the work as shown in plan 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);
            3.   A copy of the regulatory floodplain map with the project site delineated and marked to reflect any proposed change in the regulatory floodplain location; and
            4.   All changes in grade resulting from any proposed excavation or filling; the location and dimension 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 this chapter.
         (c)   Engineering calculations and supporting data showing that the proposed work will meet the performance standards outlined in § 151.149;
         (d)   Elevation certificates of the lowest floor (elevation including basements) for all existing buildings in the regulatory floodplain;
         (e)   Flood-proofing certificates for all existing buildings, or portions thereof, located below the flood protection elevation; and
         (f)   Evidence that all required federal, state, and local permits have been obtained. (See Appendix G for a partial list of permits that may be required.)
   (C)   Regulatory floodways.
      (1)   Determination and delineation. The location of the regulatory floodway shall be as delineated on the Illinois Department of Natural Resources, Office of Water Resources designated regulatory floodway maps listed in Appendix M, as may be amended by the Federal Emergency Management Agency. Where interpretation is needed to determine the exact location of the regulatory floodway boundary, the Illinois Department of Natural Resources, Office of Water Resources shall be contacted. A site located in the regulatory floodway that is higher than the base flood elevation is subject to the regulations of § 151.150 until such time as a Letter of Map Amendment or Letter of Map Revision is received from the Illinois Department of Natural Resources, Office of Water Resources and Federal Emergency Management Agency.
 
COMMENTARY:
Current Federal Emergency Management Agency maps can be obtained from the Planning, Building and Development Department or online (http://maps.lakecountyil.gov/mapsonline).
 
      (2)   Permitted uses.  No encroachment shall be allowed in the regulatory floodway, except as explicitly permitted by § 151.150.
      (3)   Additional application requirements.  In addition to other submittal requirements, the following additional information shall be provided for all development in the regulatory floodway:
         (a)   Site location of the property, drawn to scale on the regulatory floodway map;
         (b)   Plans, cross-sections, and profiles of the project showing:
            1.   The regulatory floodway limit and, if applicable, the navigation channels for work in public bodies of water as defined by the Illinois Department of Natural Resources, Office of Water Resources;
            2.   Cross-section views of the project for the impacted reach showing existing and proposed conditions including principal dimensions of the work as shown in plan 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);
            3.   A copy of the regulatory floodway map with the project site delineated and marked to reflect any proposed change in the regulatory floodway location; and
            4.   All changes in grade resulting from any proposed excavation or filling; the location and dimension 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 this chapter.
         (c)   Engineering calculations and supporting data showing that the proposed work will meet the performance standards outlined in § 151.150, and if applicable, § 151.151 and § 151.152;
         (d)   Elevation certificates of the lowest floor (elevation including basements) for all existing buildings in the regulatory floodway; and
         (e)   Evidence that all required federal, state, and local permits have been obtained. (See Appendix G for a partial list of permits that may be required.)
   (D)   Flood table lands.
      (1)   Determination and delineation.  Flood table land is that land area contiguous to the floodplain, the elevation of which is greater than the base flood elevation by two feet or less.
      (2)   Permitted uses.  All uses permitted by the underlying zoning district shall be permitted by right on flood table lands subject to compliance with the standards of § 151.153.
   (E)   Flood-prone areas.
      (1)   Determination and delineation.  Flood-prone areas are delineated by projecting the base flood elevation onto the best available topographic information.
      (2)   Permitted uses.  All uses permitted by the underlying zoning district shall be permitted by right in flood-prone areas subject to compliance with the standards of § 151.154.
   (F)   Other regulations to apply.  In addition to the provisions of this section that apply to regulatory floodplain, regulatory floodway, flood table land and flood-prone areas, the regulations of the Zoning District in which land is located shall continue in full force and effect. Likewise, nothing in this section shall relieve the developer of any responsibility for fully complying with all requirements of the Illinois Department of Natural Resources, Office of Water Resources, the Federal Emergency Management Agency, the U.S. Army Corps of Engineers or any other federal, state, or local agency having jurisdiction over the filling or development of regulatory floodplain or regulatory floodway lands.
(Ord., § 8.3, passed 10-13-2009; Ord. passed 10-9-2012; Ord. passed - -)