M3 Engineering was selected to restore 1,700 feet of degrading stream in St. Charles, MO.  The stream is downcutting and the banks are collapsing in several locations, threatening several properties.  M3 will model the stream using HEC-RAS to determine the hydraulic characteristics, and performed a geomorphic assessment to determine the root cause of the degradation and will then decide which restoration techniques are suitable for repairing the stream.

Eroded Bank- Cole Creek

Increased imperviousness within the Cole Creek watershed has led to increased peak flows and total runoff volumes.  The stream is suffering from ongoing degradation in certain sections, including the 1,700 foot section between Southwick and Droste.  There are 36 properties that are affected by the degradation, which includes downcutting, bank sloughing, toe scour and exposed piping. 

 M3 Engineering will address the situation by first performing a geomorphic assessment of the stream to determine the root causes of the degradation.  An environmental scientist and a hydraulic engineer will walk the length of the stream to assess the existing stream conditions and to inventory the current vegetation.  A HEC-RAS model will be prepared to define the existing and proposed hydraulic conditions. Any improvements must not cause a rise in the 100 year water surface elevation.

Proposed biostabilization techniques include wrapped earth, rock toe, riffle-pool complex, willow staking and root wads.  The solutions are designed to restore the stream with natural, sustainable, methods that create wildlife habitat.