Section 3702.50  Requirements for Approval of Permits for Removal of Dams

a)         Dependent upon the size, height, reservoir impounding capacity, upstream and downstream channel conditions, existing reservoir sediment deposits, degree of hazard in case of failure, as well as any other considerations which might be peculiar to a particular dam, the following OWR requirements shall be met unless the applicant establishes that one or more specific requirements for a permit to remove a dam are not applicable.

b)         A reasonable method to accomplish the following requirements will be accepted. It is strongly recommended that applicants contact OWR prior to initiation of studies and at any time during the development of the permit application if questions should arise.

1)         Reservoir Dewatering – The reservoir shall be dewatered with a method and timing such that the downstream channel shall not overflow to a degree to cause damage.

2)         Effecting Breach – A breach shall be made in such a manner as to be safe under all reasonably anticipated storm events.

3)         Size of Breach – The waterway cross sectional area of the final breach shall be sufficient to at least pass the 100-year frequency flood with negligible backwater effect.

4)         Control of Erosion at Site of Breach During and After Breaching Operations – Erosion of the dam embankment and adjacent area shall be controlled during and after breaching operations by proper breach procedure, use of appropriate structural measures, and necessary maintenance measures thereafter.

5)         Downstream Channel Impacts – Effects of the breach on the downstream channel shall be assessed.  Increases in water levels downstream of the breach over that which occurred prior to construction of the dam shall be negligible unless the owner can show that no damage results from such increases.  If increases in water levels are not negligible or if damage can result from the breach, OWR will require the owner to mitigate such damages.

6)         Restoration of Original Channel Upstream of Breach – The original channel shall be restored, or an alternate channel shall be required to provide flows approximating the original flow regime (restoration to the extent possible, of the channel and stream flows to original conditions prior to construction of the dam) through the bed of the reservoir from the breach to the upstream end of the area impacted by the reservoir.

7)         Control of Sediment Deposits in Reservoir – Measures shall be undertaken to minimize movement of reservoir sediment deposits through the breach.

8)         Restoration of Reservoir Lake Bed – The bed of the reservoir within the 100-year flood plain shall be restored to a condition whereby it can serve a reasonable flood plain use.

9)         Plan for Maintenance – A plan for providing regular maintenance of the breach, outlet channel, inlet channel, and reservoir bed will be required by OWR, for the period of time necessary to establish plant cover or other erosion and sedimentation control.

(Source:  Amended at 11 Ill. Reg. 1941, effective January 13, 1987)