Feather River Levee Setback Project
Prior to joining cbec, select cbec staff members provided geomorphic and ecosystem enhancement services to the Three Rivers Levee Improvement Authority (TRLIA) on the Feather River Levee Setback Project.
Working in collaboration with local, state, and federal interests, this levee setback project designed and constructed a six-mile-long setback levee along the Feather River, in an area that had previously been devastated by two major floods since 1986. This project is a follow-on project to the Bear River Levee Setback project; however, it is approximately three times the size of the Bear River project in terms of setback area and length of new levee (length of new levee = 5.7 miles).
Project feasibility and design commenced in 2006 with implementation completed in 2010. Some areas of the levee were completely rebuilt while other segments were bolstered by the construction of cutoff walls, stability berms, and relief and monitoring wells to address under-seepage and through-seepage.
The levee setback project is the second of its kind in the Central Valley of California (after the Bear River Levee Setback Project) and includes multi-objective, holistic, floodplain management elements such as:
- Flood risk reduction, through protection of nearby development by the new setback levee, and reduction of the water surface elevation of peak flood events due to increased conveyance capacity provided by the increased floodplain area.
- Ecosystem enhancement opportunities through riparian restoration of the newly exposed floodplain.
While at their previous employer, current cbec staff members directed the technical geomorphic reconnaissance and studies. This included sediment transport analyses to quantify the transport regime of the setback floodplain and associated main channel of the Feather River in comparison to the pre-project conditions.