Bio-engineered StreamBank Stabilization Using Wetland Sod on the Teton River: A Case Study

Abstract

Abstract. Wetland sod in combination with erosion control fabric was used to reconstruct and stabilize an eroding streambank on the Teton River in southeast Idaho. The river has an average base flow of 5.67 m 3 /s and an average peak flow of 34 m 3 /s. Above and throughout the study area the Teton River is a predominantly ground water fed, free flowing system with a moderate spring runoff. Conditions at the study site pre-construction included an average bank height of 1.07 m, an average bank slope of 2:1 and dominant bank vegetation consisting of introduced pasture grasses. The dominant soil type was a silty clay loam. The existing bank was reconstructed by first excavating the bank down to the baseflow water line to a width of 3.66 m. Two layers of long-term erosion control fabric were staked onto the base of the excavated bank using 20 cm wire staples. Soil was compacted onto the erosion control fabric layers to a depth of 0.30 m. Approximately 1 m of the erosion control fabric was wrapped up onto the compacted soil to build the initial toe of reconstructed bank. The remaining soil was sloped back to create a bank with an average slope of 3:1. Wetland sod, a pre-vegetated coir product planted with native sedges and rushes, was installed in two rows onto the constructed toe and remaining bank to a width of 1.83 m. A total of 77 m of eroding bank was reconstructed in 2 days at a cost of $195 per linear meter. In 1 month post construction the pre-vegetated coir material was fully rooted and could not be displaced by human or animal disturbance. Additional