(A) The proposed structure shall not result in an increase of upstream flood stages greater than one- tenth of a foot when compared to the existing conditions for all flood events up to and including the 100-year frequency event; or the upstream flood stage increases will be contained within the channel banks (or within existing vertical extensions of the channel banks) such as within the design protection grade of existing levees or flood walls or within recorded flood easements. If the proposed construction will increase upstream flood stages greater than one-tenth of a foot, the developer must contact IDNR-OWR Dam Safety Section for a dam safety permit or waiver.
(B) The engineering analysis of upstream flood stages must be calculated using the flood study flows, and corresponding flood elevations for tailwater conditions for the flood study specified in § 152.004. Bridges and culverts must be analyzed using any commonly accepted FEMA approved hydraulic models.
(C) Lost floodway storage must be compensated for per § 152.037.
(D) Velocity increases must be mitigated per § 152.038.
(E) If any work is proposed in, near or over a public body of water, a permit or letter indicating a permit is not required must be obtained from IDNR-OWR.
(F) The hydraulic analysis for the backwater caused by the bridge showing the existing condition and proposed regulatory profile must be submitted to IDNR-OWR for concurrence that a CLOMR is not required by § 152.028.
(G) All excavations for the construction of the crossing shall be designed per § 152.043.
(H) For modification or replacement of existing structures, the existing structure must first be evaluated in accordance with IDNR-OWR Rules to determine if the existing structure is a source of flood damage. If the structure is a source of flood damage, the applicant’s engineer shall submit justification to allow the damage to continue and evaluate the feasibility of relieving the structure’s impact. Modifications or replacement structures shall not increase flood stages compared to the existing condition for all flood events up to and including the base flood event. The evaluation must be submitted to IDNR-OWR, for review and concurrence before a permit is issued. The village shall be copied on all related correspondence.
(I) Construction vehicles shall cross streams by the means of existing bridges or culverts. Where an existing crossing is not available, a temporary crossing that has been issued a permit or waiver by IDNR-OWR shall be constructed in which:
(1) The approach roads will be one-half foot or less above the existing grade.
(2) The crossing will allow stream flow to pass without backing up the water above the stream bank vegetation line or above any drainage tile or outfall.
(3) The top of the roadway fill in the channel will be at least two feet below the top of the lowest bank. Any fill in the channel shall be non-erosive material, such as rip-rap or gravel.
(4) The access road and temporary crossings will be removed within one year after installation, unless an extension of time is granted by the village.
(Ord. 3187, passed 1-22-19) Penalty, see § 152.999