A design has been finalized to stabilize 650-feet of eroding Rum Riverbank at Dellwood River Park in St. Francis. Erosion of the riverbank is causing numerous trees to fall into the river and is threatening a popular walking trail. The project design, currently in the permitting phase, features three primary protection measures;
1) Two severely eroding zones of riverbank encroaching on the trail will be built back out, armored with rock riprap, and potentially have large tree root-wads added to provide in-stream habitat elements. The riprapped length of bank will total approximately 180-feet in length.
2) Three bendway weirs constructed of rock will protrude at a 45° into the river. These low-lying, linear features will be submerged under the water, and will push flow and erosive scour back toward the middle of the channel, rather than along the outer bank. The bendway weirs will also add variable flow areas and habitat value in the channel. These will be great features to cast around for any fisher folks from shore!
3) And finally, the less severe eroding areas of riverbank will be armored with cedar trees in a technique called a "cedar tree revetment". Cut eastern red cedars will be cabled together in a shingled fashion along the bank and secured with earth anchors driven into the soil. This is a bioengineering approach that is softer and less expensive than rock which should help the bank stabilize, vegetate, and stabilize over time before the cedar trees eventually rot away.