Stabilizing & Sprucing Up a Stream Channel
When a sharp turn in a stream began eroding homeowners’ yards in storm events, the city of Florence, Ky., needed a solution—and fast. Erosion to the 10-ft-high streambank was becoming a major issue, and the city wanted to take care of the problem before it caused serious damage.
The city worked with engineers from Viox and Viox and H. C. Nutting/Terracon to tackle the issue and find the best solution. Florence officials also held public meetings and met with property owners as they worked toward a solution.
The city’s goals for the project included stabilizing the streambanks and creating an aesthetically pleasing green area for residents along the creek to enjoy. Minimizing excavation and disturbance to residential yards was also a priority.
Solution Selection
“The ability to construct the wall without geogrid reinforcement was critically important to this project,” said Justin M. Verst, P.E., of Viox and Viox. “The construction space was tight.”
“We originally considered using gabion baskets or plain concrete walls, but we wanted an aesthetic finish to the channel,” said City of Florence Project Manager Peter Glenn. “We chose Redi-Rock because we had more finish options, including the new Ledgestone face. Plus, it was very economical.”
Massive 1-ton Redi-Rock harness the power of gravity to build tall walls that often do not require reinforcement. For this project, the ability to build the 13.5-ft-high channel walls without reinforcement minimized excavation and disturbance to adjacent properties and yards.
The walls have a proven track record in storm channel applications. The blocks stack like giant toy building bricks, making them quick and easy to install using an excavator and a small crew. Local manufacturer Redi-Rock Structures of OKI worked closely with the city of Florence to provide a solution for this project.
According to Jeff Barrow, P.E., of H.C. Nutting/Terracon, Redi-Rock’s new Ledgestone face “matches the Cincinnati and northern Kentucky limestone bedrock we have in our area, so it’s very visually appealing.” The blocks have the same dimensions, weight and engineered capabilities as other company blocks, but with the look of natural, stacked ledgestone.
“It’s a home run when you can put up an aesthetic channel like this instead of the usual concrete channel or gabion baskets, economically,” Glenn said.
Design & Implementation
After photo documentation of the site, H. C. Nutting/Terracon performed the global and internal stability calculations for the channel walls and designed erosion control features.
The designs called for a reinforced concrete footer to act as the base of the wall. On top of the concrete footer, two courses of 60-in.-deep Redi-Rock bottom blocks were installed, followed by 41-in.-deep blocks for the rest of the wall.
“The flow from one of the creeks was overriding the top of the wall, so we designed a controlled density fill to reinforce the back of the wall as the flow would go over the top. We made the wall impermeable to water to prevent erosion or scour from behind the wall,” Barrow said.
Due to environmental permitting, the entire channel had to be constructed from the top of the streambanks. Contractor Dudley Construction Co. cut benches along the creek banks and selected Redi-Rock of Kentuckiana to assemble the wall as they started at one end of the channel and backed their way out.
In total, the 4,800-sq-ft combination of walls took less than two weeks to install. At the highest point, the walls stand at 13.5 ft. Once the walls were completed, Dudley Construction Co. installed a decorative metal fence along the top edge of the channel.