(A) The bridge or culvert and roadway approach reconstruction or modification shall be constructed with no more than one-tenth of a foot increase in backwater over the existing flood profile for all flood frequencies up to and including the 100-year event, if the existing structure is not a source of flood damage.
(B) If the existing bridge or culvert and roadway approach is a source of flood damage to buildings or structures in the upstream floodplain, the applicant’s engineer shall evaluate the feasibility of redesigning the structure to reduce the existing backwater, taking into consideration the effects on flood stages on upstream and downstream properties.
(C) The determination as to whether or not the existing crossing is a source of flood damage and should be redesigned must be prepared in accordance with the 17 Ill. Adm. Code, Chapter I, IDNR Part 3708 (Floodway Construction in Northeastern Illinois) and submitted to the Division IDNR-OWR for review and concurrence before a permit is issued.
(Ord. 3187, passed 1-22-19) Penalty, see § 152.999