Erosion and Sediment Control on Long Slopes

This presentation offers the story of the US20 safety bypass project through the eyes of the erosion and sediment control designer. US20 is a busy route between Oregon's Willamette Valley and the central coast. The old road, along the Yaquina River was a narrow twisty route constrained by steep canyon walls and the river. This road was the site of frequent and severe accidents. The bypass route was engineered to go over the ridges of the Coast Range. True to its reputation, the location is among the wettest regions in one of the wettest states in the US, with the regional ecosystem considered temperate rain forest. The setting, through working forests was not pristine, however the location is rich with wildlife, scenic beauty and the receiving waters, the Yaquina River, is habitat of two endangered species, the Coho and Chinook Salmon. The geology of the site is ancient sea bed strata of soft sandstone. High rainfall and long, steep slopes combine to make a site prone to erosion and landslides. Further complicating the issue is that the original highway construction work was so beset by engineering, construction and environmental issues, that work was stopped the contractor removed and the entire project strategy revised. This presentation documents early issues with the first project and my involvement in the second (and successful) project. The erosion and sediment controls for this second project ranged from simple to innovative, but all were employed in great quantities. The completion of this second project provided lessons learned, regulatory requirements met and the highway completed to provide safe passage between Oregon's rich Willamette Valley and the scenic Oregon coast.