(A) This chapter’s protection standard is based on the Flood Insurance Study for the city.
(1) 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 from federal, state or other sources.
(2) When a party disagrees with the best available data, they shall submit a detailed engineering study needed to replace existing data with better data and submit it to IDNR/OWR and FEMA for review and consideration prior to any development of the site.
(B) The base flood or 100-year frequency flood elevation for the SFHAs of any streams flowing through the city’s boundaries shall be as delineated on the 100-year flood profiles in the Flood Insurance Study of Cook County prepared by FEMA dated 8-19-2008, 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 Cook County that are within the extraterritorial jurisdiction of the city or that may be annexed into the city shall be as delineated on the 100-year flood profiles in the Flood Insurance Study of Cook County by FEMA and dated 8-19-2008, 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 of Cook County.
(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 of Cook County shall be according to the best existing data available from federal, state or other sources. Should no other data exist, an engineering study must be financed by the applicant to determine base flood elevations.
(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-H, HEC-RAS 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 or HIP, or by techniques presented in various publications prepared by the United States Geological Survey for estimating peak flood discharges.
(3) For a non-riverine SFHA, the base flood elevation shall be the historic flood of record, plus three feet, unless calculated by a detailed engineering study.
(4) For an unmapped extended SFHA (with a drainage area less than one square mile) which has been identified by the city pursuant to § 156.020(C) of this chapter, the base flood elevation shall be determined by the applicant utilizing a method as approved in division (D) above.
(Prior Code, § 157.004) (Ord. 08-023, passed 7-22-2008)