The Hamilton County Parks Department in Cincinnati was losing a 30-ft high, 850-ft long segment of river bank at Lake Isabella Park to the erosive forces of Little Miami River. Strong water currents and frequent water-level changes had caused the bank’s slope to degrade so that it was nearly vertical in most areas.
The bank separates Lake Isabella, a man-made lake in the park, and the Little Miami River, which was designated as a Wild and Scenic River by state and federal governments. The steep bank posed a safety risk to people who used the park, and its continued erosion posed an environmental risk to the river, which contains many species of fish and mollusks that are sensitive to sedimentation and habitat alteration.
As a result of the river’s environmental designation, the team was unable to use traditional revetment materials, such as concrete, timber or large riprap. Vegetative revetments alone lacked the strength to endure the river’s hydraulic forces. Consequently, team members had to find alternative methods and materials to complete the project. They conceived an integrated earth-retention system that combined synthetic and natural erosion-control systems to meet aesthetic and environmental requirements.