West Chester Township, just outside of Cincinnati, Ohio, has seen tremendous growth as the Cincinnati-Dayton metropolitan areas continue to converge. Recently, West Chester’s new Towne Center was developed, with a two-acre park and open space for concerts and other events. The Square overlooks a pond that catches storm water runoff from the Towne Center, creating a functional yet attractive focal point for the development.
The pond’s banks were lined with rip rap in some areas but needed more reinforcement to deal with the rise and fall of the water as well as the freeze-thaw cycles. “The number one reason Redi-Rock was chosen for this project was aesthetics. The second reason was durability. With the freeze thaw cycle here in Ohio and the water environment, we just had to have a solid block,” said project engineer Joe Kowalski, P.E.
Redi-Rock’s classic Cobblestone face tied the retaining wall in well with the aesthetics of the development. Though each massive block is nearly six feet, the cobblestone texture gives the appearance of six smaller blocks. This allows developers to achieve the look of a high-end professional landscape wall with the efficient and easy installation of a big-block system.
The 7,000 square foot wall lining the retention pond was designed to be 10.5 ft. tall with 1.5 to 3 ft. buried. The ground surface below the wall is submerged and is inclined at 2H:1V. The walls were constructed in a dry condition, prior to allowing the pond to fill. Crews from Sunesis Construction prepared the leveling pad by digging a 48 in. wide trench the length of the wall and compacting the existing soils. The trench was then lined with 12 in. of No. 57 crushed stone and leveled. Installing a leveling pad to the engineer’s specifications ensured that the rest of wall construction would be level.
A majority of the project utilized Redi-Rock’s 41″ series block. The engineering plans called for a 4″ diameter flexible, corrugated, slotted drain pipe and a permanent drain outside the wall to be sure the water drains properly from behind the wall. Kowalski also called for a one-foot gravel drainage zone behind the entire height of the wall to allow the wall to drain properly. Because retaining wall failures often result from insufficient or improper drainage, preparing a proper base and installing drainage are critical steps.
The wall currently lines about one third of the pond, and the rest is still rip rap and natural bank. Redi-Rock Structures of OKI will be supplying blocks to provide erosion control for another section of the pond. The Towne Centre pond underscores the fact that storm water management need not be an eyesore… By designing this retention pond with aesthetics in mind, designers were able to capitalize on their storm water solution rather than hide it.