(A) No development in the SFHA where a floodway has not been determined shall create a damaging or potentially damaging increase in flood heights or velocity or threat to public health, safety and welfare or impair the natural hydrologic and hydraulic functions of the floodway or channel, or impair existing water quality or aquatic habitat. Construction impacts shall be minimized by appropriate mitigation methods as called for in this chapter.
(B) Within all riverine SFHAs where the floodway has not been determined, the following standards shall apply:
(1) The developer shall have a licensed professional engineer state in writing and show through supporting plans, calculations, and data that the project meets the engineering requirements of § 159.42(C)(1) through § 159.42(C)(9) for the entire floodplain as calculated under the provisions of § 159.05(D).
(2) As an alternative, the developer should have an engineering study performed to determine a floodway and submit that engineering study to IDNR/OWR and FEMA for acceptance as a designated floodway.
(4) A development permit shall not be issued unless the applicant first obtains an IDNR/OWR permit or written documentation that a permit is not required from IDNR/OWR, issued pursuant to ILCS Ch. 615, Act 5, §§ 5 et seq.
(5) No permit from IDNR/OWR shall be required if the division has delegated permit responsibility to the city per 17 Ill. Adm. Code, Part 3708, for designated floodways.
(6) Permits for dams.
(a) Any work involving the construction, modification or removal of a dam as defined in § 159.02 per 17 Ill. Adm. Code Part 3702 (Rules for Construction of Dams) shall obtain an IDNR/OWR permit prior to the start of construction of a dam.
(b) If the City Engineer finds a dam that does not have an IDNR/OWR permit, the City Engineer shall immediately notify the IDNR/OWR Bartlett office.
(c) If the City Administrator or his designee finds a dam which is believed to be in unsafe condition, the City Administrator or his designee shall immediately notify the owner of the dam, the IDNR/OWR Bartlett office, and the Illinois Emergency Management Agency (IEMA).
(C) The following activities may be permitted without a licensed professional engineer's review or calculation of base flood elevation and designated floodway. Such activities shall still meet the other requirements of this chapter.
(1) Bridge and culvert crossings of streams in rural areas meeting conditions of IDNR/OWR Statewide Permit No. 2;
(2) Barge fleeting facilities meeting conditions of IDNR/OWR Statewide Permit No. 3;
(3) Aerial utility crossings meeting conditions of IDNR/OWR Statewide Permit No. 4;
(4) Minor boat docks meeting conditions of IDNR/OWR Statewide Permit No. 5;
(5) Minor, non-obstructive activities meeting conditions of IDNR/OWR Statewide Permit No. 6. Activities (not involving fill or positive change in grade) are covered by this permit;
(6) Outfall structures and drainage ditch outlets meeting conditions of IDNR/OWR Statewide Permit No. 7;
(7) Underground pipeline and utility crossings meeting the conditions of IDNR/OWR Statewide Permit No. 8;
(8) Bank stabilization projects meeting the conditions of IDNR/OWR Statewide Permit No. 9;
(9) Accessory structures and additions to existing residential buildings meeting the conditions of IDNR/OWR Statewide Permit No. 10;
(10) Minor maintenance dredging activities meeting conditions of IDNR/OWR Statewide Permit No. 11;
(11) Bridge and culvert replacement structures and bridge widenings meeting conditions of IDNR/OWR Statewide Permit No. 12;
(12) Temporary construction activities meeting conditions of IDNR/OWR Statewide Permit No. 13;
(13) Special uses of public waters meeting conditions of IDNR/OWR Statewide Permit No. 14; and
(14) Any development determined by IDNR/OWR to be located entirely within a flood fringe area shall be exempt from state floodway permit requirements.
(D) The flood carrying capacity of any altered or relocated watercourse shall be maintained.
(E) Compensatory storage.
(1) Whenever any portion of a floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the base flood or 100-year frequency flood elevation shall be compensated for and balanced by a hydraulically equivalent volume of excavation taken from below the base flood or 100-year frequency flood elevation.
(2) The excavation volume shall be at least equal to 1.5 times the volume of storage lost due to the fill or structure.
(3) In the case of streams and watercourses, such excavation shall be made opposite or adjacent to the areas so filled or occupied.
(4) All floodplain storage lost below the existing ten-year flood elevation shall be replaced below the proposed ten-year flood elevation. All floodplain storage lost above the existing ten-year flood elevation shall be replaced above the proposed ten-year flood elevation. All such excavations shall be constructed to drain freely and openly to the watercourse.
(Ord. 2008-08-0196O, passed 8-12-2008; Am. Ord. 2019-10-0759O, passed 10-22-2019) Penalty, see § 159.99