Middle Fork Saline River Channel Modification and Bridge Design | American Coal Company

To enable productive mining and protect a 3 mile section of Illinois State Route 34 including 17 highway and railroad bridges, Knight Engineers & Architects completed an evaluation of the existing hydrologic and hydraulic characteristics of the 40 square mile watershed. Alternatives to allow continued mining without closure of the state highway were identified and evaluated for impacts to flooding and natural resources with the chosen alternative incorporating a 3000-foot long channel modification of the Middle Fork Saline River. Detailed modeling of the watershed using the unsteady flow module of the HEC-RAS program was utilized to design the new channel configuration as well as the waterway openings for the 17 highway and railroad bridges. The modeling efforts included accounting for the significant topographic changes caused by the mining ground subsidence. The results of the model were used to demonstrate no adverse impact to flood characteristics due to the proposed mining activities. An expedited schedule to obtain the pertinent regulatory approvals was achieved due to the Knight’s experienced water resources engineering staff and their long standing relationships with the regulatory agencies. The final design for the project will eliminate three existing railroad bridges and three existing state highway bridges thereby reducing the annual maintenance costs for Canadian National Railroad and well as the Illinois Department of Transportation.