IMA was contracted by the owner of this property to stabilize an eroding bank to prevent a channel avulsion on the Lemhi River.  This reach of river has been subject to channel straightening and extensive rip rap installation.  As a result, the project reach experiences abnormally high hydraulic forces and the client had been losing property at a concerning rate.  The river had demonstrated rapid erosion though a healthy stand of cottonwood trees, so conventional bioengineering techniques were not appropriate.  Instead, the bank stabilization design consisted of  a rock barb to deflect flows and an engineered log jam to hold the stream bank.  The Lemhi River contains several endangered and protected fish species.  Construction techniques and timing were critical to adhere to permit constraints.

Before - the river flow was directly into the bank, causing rapid erosion

Before - the river flow was directly into the bank, causing rapid erosion

After - the engineered log jam stabilizes the bank and slows the river flow around the corner

After - the engineered log jam stabilizes the bank and slows the river flow around the corner

After - the barb installed upstream of the log jam further helps to slow and re-direct flows

After - the barb installed upstream of the log jam further helps to slow and re-direct flows

During construction - the first toe-logs and logs with rootwads are installed and secured

During construction - the first toe-logs and logs with rootwads are installed and secured