(A) Within all riverine SFHA's where the floodway has not been determined, the standards set forth by this section shall apply.
(B) The developer shall have a registered professional engineer state in writing and show through supporting plans, calculations and data that the project meets the engineering requirements of § 153.59 (A) through (M) for the entire flood plain as calculated under the provisions of § 153.35 (E) of this chapter. As an alternative, the developer should have an engineering study performed to determine a floodway and submit that engineering study to DWR for acceptance as a regulatory floodway. Upon acceptance of their floodway by the Department, the developer shall then demonstrate that the project meets the requirements of § 153.55 for the regulatory floodway. The floodway shall be defined according to the definition in § 153.02 of this chapter.
(C) A development permit shall not be issued unless the applicant first obtains a permit from DWR or written documentation that a permit is not required from DWR.
(D) No permit from DWR shall be required if the Division has delegated permit responsibility to the village per 92 Ill. Adm. Code, Part 708 for regulatory floodways, per DWR's statewide permit entitled “Construction in Flood Plains with No Designated Floodways in Northeastern Illinois.”
(E) Dam safety permits. Any work involving the construction, modification or removal of a dam or an on-stream structure to impound water as defined in § 153.02 shall obtain an Illinois Division of Water Resources dam safety permit or letter indicating a permit is not required prior to the start of construction of a dam. If the Building Inspector finds a dam that does not have a DWR permit, the Building Inspector shall immediately notify the Dam Safety Section of the Division of Water Resources. If the Building Inspector finds a dam which is believed to be in unsafe condition, the Building Inspector shall immediately notify the owner of the dam and the Illinois Emergency Services and District Agency (ESDA), and the DWR, Dam Safety Section in Springfield.
(F) The following activities may be permitted without a Registered Professional Engineer's review or calculation of a base flood elevation and regulatory floodway. Such activities shall still meet the other requirements of this chapter.
(1) Underground and overhead utilities that:
(a) Do not result in any increase in existing ground elevations; or
(b) Do not require the placement of above ground structures in the floodway; or
(c) In the case of the underground stream crossings, the top of the pipe or encasement is buried a minimum of three feet below the existing stream bed; and
(d) In the case of overhead utilities, no supporting towers are placed in the watercourse and are designed in such a fashion as not to catch debris.
(2) Storm and sanitary sewer outfalls that:
(a) Do not extend riverward or lakeward of the existing adjacent natural bank slope; and
(b) Do not result in an increase in ground elevation; and
(c) Are designed so as not to cause stream erosion at the outfall location.
(3) Construction of shoreline and streambed protection that:
(a) Does not exceed 1000 feet in length or two cubic yards per lineal foot of streambed.
(b) Materials are not placed higher than the existing top of bank.
(c) Materials are placed so as not to reduce the cross-sectional area of the stream channel by more than 10%.
(d) Vegetative stabilization and gradual side slopes are the preferred mitigation methods for existing erosion problems. Where high channel velocities, sharp bends or wave action necessitate the use of alternative stabilization measures, natural rock or rip-rap are preferred materials. Artificial materials such as concrete, construction rubble, and gabions should be avoided unless there are no practicable alternatives.
(4) Temporary stream crossings in which:
(a) The approach roads will be 0.5-foot or less above natural grade.
(b) 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 invert.
(c) 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 nonerosive material, such as rip-rap or gravel.
(d) All disturbed stream banks will be seeded or otherwise stabilized as soon as possible upon installation and again upon removal of construction.
(e) The access road and temporary crossings will be removed within one year after authorization.
(5) The construction of light poles, sign posts and similar structures;
(6) The construction of sidewalks, driveways, athletic fields (excluding fences), patios and similar surfaces which are built at grade;
(7) The construction of properly anchored, unwalled, open structures such as playground equipment, pavilions, and carports built at or below existing grade that would not obstruct the flow of flood waters;
(8) The placement of properly anchored buildings not exceeding 70 square feet in size, nor ten feet in any one dimension (such as, animal shelters and tool sheds);
(9) The construction of additions to existing buildings which do not increase the first floor area by more than 20%, which are located on the upstream or downstream side of the existing building, and which do not extend beyond the sides of the existing building that are parallel to the flow of flood waters;
(10) Minor maintenance dredging of a stream channel where:
(a) The affected length of stream is less than 1000 feet.
(b) The work is confined to reestablishing flows in natural stream channels, or
(c) The cross-sectional area of the dredged channel conforms to that of the natural channel upstream and downstream of the site.
(G) The flood carrying capacity within any altered or relocated watercourse shall be maintained.
(Ord. 553, passed 10-2-89; Am. Ord. 703, passed 4-6-92; Am. Ord. 789, passed 1-24-94)