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University of MissouriEngineers Team Up on the Big Muddy NFWR to Save a Bridge
Midwest Region, March 5, 2009
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University of Missouri Engineer Students use teamwork to armor a stream bank and build a weir to protect a footbridge on the Big Muddy National Fish and Wildlife Refuge.
University of Missouri Engineer Students use teamwork to armor a stream bank and build a weir to protect a footbridge on the Big Muddy National Fish and Wildlife Refuge. - Photo Credit: n/a

The Big Muddy National Fish and Wildlife Refuge built a foot bridge on its Jameson Island Unit in the spring of 2006.  Funding for the construction came from a Fish and Wildlife Foundation grant.  The bridge crossed an ephemeral stream, occasionally dammed by beavers, creating a beneficial wetland. 

 

Since construction, the area has experienced higher than normal precipitation.  The occasional dry stream and beaver marsh has became a raging torrent.  Beaver dams were abandoned and the stream has not since stopped flowing.  The flowing water gradually eroded away the soil around the piers supporting the bridge. To help fix this problem, the Refuge approached the University of Missouri Civil Engineering Department for some advice on ways to save the bridge. 

 

After several visits to the site, a plan was developed and Dr. John Bowders of the University of Missouri Civil Engineering Department put the plan into action using engineering students.  Engineering student Adam Frankenburg designed a rock weir to catch sediment in the stream. Adam mapped the watershed and calculated sediment transport. He also planned rock armoring around the piers and up to the weir to reduce further erosion.  The weir design catches lost sediment to help build the foundation of soil lost around the bridge piers. 

 

On Thursday March 5, 2009, a volunteer team of seven engineering students and Dr. Bowders joined four refuge staff members and one local volunteer to move almost 40 tons of ditch rock.  Ditch rock is larger rock averaging 6-18 inches in diameter and weighing from 5 to 30 pounds.  The rock was placed over a layer of geotextile armoring the creek.  Geotextile placed between layers of rock reinforces the weir and acts as a sediment filter while still allowing water to pass through.   

 

While it took nearly eight hours of hard work to completed the project, the refuge and its visitors will be able to safely use this bridge for many years to come.


Contact Info: Tim Haller, 573-441-2799, tim_haller@fws.gov



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