Florence Stream Channel
19.5 Foot (5.9 Meter) Tall Gravity Wall Provides Erosion Control for Apartment Complex
Location: Florence, Kentucky
Year Built: 2010
Goal: Residential Erosion Control
Project Duration: Installed -- 2 weeks
Project Magnitude: 4,800 sq. ft.
Height: 13.5 ft.
Gravity Retaining Wall Blocks - Massive, one-ton Redi-Rock gravity blocks rely on the sheer mass of each block to hold back the earth.
When a sharp turn in a stream began eroding homeowners’ yards during storm events, the city of Florence, Kentucky needed a solution, and fast. Erosion to the 10 ft. high stream bank was becoming a major issue, and the city wanted to take care of the problem before it caused serious damage.
The city’s goals for the project included stabilizing the stream banks, and creating an aesthetically pleasing green area for residents along the creek to continue to enjoy, while minimizing disturbance to residential yards. “The ability to construct the wall without geogrid reinforcement was critically important to this project,” explained Justin M. Verst, P.E. with Viox & Viox. “The construction space was tight.”
“We chose Redi-Rock because we wanted an aesthetic finish to the channel and Redi-Rock had more finish options—including the Ledgestone face. Plus, it was very economical,” explained City of Florence Project Manager Peter Glenn.
Massive, one-ton Redi-Rock blocks are known for their ability to harness the power of gravity to build tall walls that often don’t require reinforcement. For this project, the ability to build the 13.5 ft. high channel walls without reinforcement allowed the walls to be built with minimum excavation and disturbance to the adjacent properties and yards.
Redi-Rock walls have a proven track record in storm channel applications. The blocks stack like giant Legos, 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 Redi-Rock solution for this project.
“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.
After photo-documentation of the site, H. C. Nutting/Terracon performed the global and internal stability calculations for the channel walls, as well as designed erosion control features so the wall could handle the high water flow. 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 Redi-Rock blocks for the rest of the wall. One section of the walls has a unique backfill design to compensate for the high water flow during storm events at the intersection of the streams.
“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. [This way] the flow would go over the top. We made the wall impermeable to water to prevent erosion or scour from behind the wall,” Barrow explained.
At the time which Redi-Rock Structures of OKI was awarded the project, Redi-Rock was just beginning to produce the new Ledgestone face blocks. The production crew had to work closely with the contractor Dudley Construction Co. and the installer Redi-Rock of Kentuckiana to synchronize production and shipment to ensure the wall would go up quickly.