Potential flow velocities were significant enough to eliminate natural stabilization techniques.
CSAH 6 Ditch Restoration
Sibley County, Minnesota
Eastern Sibley County experienced a high intensity rainfall that caused significant erosion on the roadside ditch of CSAH 6. The storm created erosive flow velocities, sweeping away the existing 12-inch revetment stones over a 1,300-foot stretch of roadside ditch with a 35-foot drop. Bolton & Menk analyzed the flow conditions from the existing upstream box culvert and proposed a design to prevent future erosion. It was determined potential flow velocities were significant enough to eliminate natural stabilization techniques. In fact, there was even concern the largest revetment stones would not be stable. Bolton & Menk proposed a series of 3 to 5 foot boulder cross vanes with the largest readily-available revetment lining the channel between each cross vane. The boulder cross vanes were installed with riprap. The constructed controls can now effectively handle extreme flow velocities.