(A) This chapter’s protection standard is based on the Countywide Flood Insurance Study for Will and Cook Counties dated February 15, 2019 and August 19, 2008 respectively, prepared by FEMA, and as amended from time to time. 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 or she may finance the detailed engineering study needed to replace existing data with better data and submit it to IDNR-OWR and FEMA.
(B) The base flood or 100-year frequency flood elevation for the SFHA’s of Hickory Creek, Hickory Creek Tributaries 1, 2, 3, A, Union Drainage Ditch, Jackson Creek, Jackson Creek Tributary 2, Jackson Branch, and Forked Creek shall be as delineated on the 100-year flood profiles in the Countywide Flood Insurance Study of Will and Cook Counties prepared by FEMA dated February 15, 2019, and August 19, 2008 respectively. These areas are shown on the Flood Insurance Rate Maps for Will County on panel numbers 17197C0195G, 17197C0212G, 17197C0213G, 17197C0214G, 17197C0218G, 17197C0310G, 17197C0326G, 17197C0327G, 17197C0330G, 17197C0331G, and 17197C0335G dated February 15, 2019; and for Cook County on panel numbers 17031 C0781 J and 17031 C0782J dated August 19, 2008, and such amendments to such study and maps as may be prepared from time to time.
(C) The base flood or 100-year frequency flood elevation for the SFHAs of those parts of unincorporated Will 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 Countywide Flood Insurance Study of Will and Cook County, Illinois prepared by FEMA dated February 15, 2019 and August 19, 2008. These areas are shown on the Flood Insurance Rate Maps for Will County on panel numbers 17197C0195G, 17197C0212G, 17197C0213G, 17197C0214G, 17197C0218G, 17197C0310G, 17197C0326G, 17197C0327G, 17197C0330G, 17197C0331G, and 17197C0335G dated February 15, 2019; and for Cook County on panel numbers 17031 C0781 J and 1 7031 C0782J dated August 19, 2008, and such amendments or revisions to such study and maps as may be prepared from time to time.
(D) 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 Countywide Flood Insurance Rate Map for Will County on panel numbers 17197C0195G, 17197C0212G, 17197C0213G, 17197C0214G, 17197C0218G, 17197C0310G, 17197C0326G, 17197C0327G, 17197C0330G, 17197C0331G, and 17197C0335G dated February 15, 2019; and for Cook County on panel numbers 17031 C0781 and 0782 dated August 19, 2008, and such amendments or revisions to such study and maps as may be prepared from time to time.
(E) The base flood or 100-year frequency flood elevation for each of the remaining SFHAs delineated as an “A Zone” on the Countywide Flood Insurance Rate Map for Will County on panel numbers 17197C0195G, 17197C0212G, 17197C0213G, 17197C0214G, I7197C0218G, 17197C0310G, 17I97C0326G, 17197C0327G, 17197C0330G, 17197C0331G, and 17197C0335G dated February 15, 2019; and for Cook County on panel numbers 17031C0781J and 1 7031 C0782J dated August 19, 2008, and such amendments or revisions to such study and maps as may be prepared from time to time, shall be according to the best existing data available in the Illinois State Water Survey Floodplain Information Repository.
(1) When no base flood or 100-year 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-RAS, HEC-2, WSP-2, or a dynamic model such as HIP.
(2) The flood flows used in the hydraulic models shall be obtained from a hydrologic model, such as HEC-HMS, HEC-1, TR-20, Pond Pack, or HIP, or by techniques presented in various publications prepared by the United States Geological Survey for estimating peak flood discharges.
(3) For an unmapped extended SFHA (with a drainage area less than one square mile) which has been identified by the Administrative Department, the base flood elevation shall be determined by the applicant utilizing a method approved in this section.
(F) In all occasions, regardless of existing flood zone, a detailed site specific flood study is required for the proposed condition when any fill is proposed within the floodplain.
(Ord. 3187, passed 1-22-19)