(A) 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 Flood Plain Information Repository. When a party disagrees with the best available data, that party may finance the detailed engineering study needed to replace existing data with better data and submit it to DWR and FEMA.
(B) The base flood or 100-year frequency flood elevation for the SFHAs of the Des Plaines River, DuPage River and Rock Run Creek South shall be as delineated on the 100-year flood profiles in the Will County, County Wide Flood Insurance Study of the village prepared by FEMA and dated September 6, 1995, and such amendments to such study and maps as may be prepared from time to time. The base flood or 100-year frequency flood elevation for the SFHAs of the Illinois River, Des Plaines River, Dresden Run, Collins Run and Aux Sable Creek shall be as delineated on the 100-year flood profiles in the Flood Insurance Study of Grundy County prepared by FEMA and dated July 18, 1985, 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 Flood Insurance Study of County prepared by FEMA and dated September 6, 1995, and such amendments or revisions to such study and maps as may be prepared from time to time. The base flood or 100-year frequency flood elevation for the SFHAs of those parts of unincorporated Grundy 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 Grundy County prepared by FEMA and dated July 18, 1985, 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 Flood Insurance Rate Map of the village.
(E) The base flood or 100-year frequency flood elevation for each of the remaining SFHAs 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 Water Survey Flood Plain Information Repository. 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-II, 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-I, 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 nonriverine SFHA, the base flood elevation shall be the historic flood of record plus three feet, unless calculated by a detailed engineering study and approved by the Illinois State Water Survey.
(Ord. 553, passed 10-2-89; Am. Ord. 703, passed 4-6-92; Am. Ord. 789, passed 1-24-94; Am. Ord. 859, passed 8-21-95; Am. Ord. 919, passed 11-4-96)