Constance Marina
Ohio River Flood Wall Performs During 20-Year Flood Event
Every Project Starts with a Purpose
Located just around the Ohio River’s bend from downtown Cincinnati, Constance Marina is a 45-boat, dry dock storage facility with a vision to become a social gathering space for boating enthusiasts before, during and after enjoying a day on the water. Marina Owner, David Landwehr, wanted to create a more attractive riverside entrance to his facility that would be able to withstand the riverbank’s harsh environment.
The first obstacle in the marina’s evolution, however, was an unusable and unsightly hillside. From a landscape management perspective, the slope was challenging to maintain — so steep, its grass could only be tamed by a hand-held weed whacker. From the water’s view, the land was unkempt and unwelcoming.
While a typical solution would be a segmental retaining wall, the marina had an additional consideration; adjacent to the hill is an outdoor living space with a patio and outdoor fireplace used by guests, and a segmental retaining wall install would require excavation of that land to stabilize the wall, destroying the existing patio and adding to the time and expense of the land improvement.
The Solution
Solving for Style, Function, and Durability
The Belgard® Mega-Tandem™ 3-in-1 Wall System was recommended to save time, money and complexity on site. The system offers the visual appeal of natural stone while creating an additional 1,890 square feet of outdoor space for the marina. Its size and mechanical structure allow walls up to 15 feet high and gravity walls up to 10 feet without reinforcing.
Patent-pending mechanical connectors enable high gravity walls without surcharge, eliminating the need for excavation. This was a major advantage for the Constance Marina site, where nearby utility lines and property boundaries limited excavation options and allowed the existing outdoor living space to remain intact.
“It’s a concept that’s different than anything else out there,” said Curt Derichs, PE, of Civil Design Professionals, who designed the retaining wall. Mega-Tandem™ panels measure 12 by 24 inches and weigh 65 pounds each, combining lighter weight with high compressive strength. “The lighter units were cheaper to ship, and the weight made them easier to use on site,” said Dave Landwehr of Structures Hardscapes Specialists.
Because of their weight, the blocks can be installed by hand, eliminating the need for larger equipment. Reinforced polypropylene connecting members create structural integrity in both curved and straight retaining and freestanding walls, and the running bond configuration eliminates the need for pattern layouts.
Meeting ASTM standards C-1372 and C-1262, Mega-Tandem™ offers a compressive strength of 8,500 psi and can exceed 10,000 psi, making it suitable for use nationwide, including cold climates with harsh freeze thaw cycles. This durability was especially important for Constance Marina, which is located in a flood plain in the Ohio Valley and could experience full submersion during flooding events.
“Mega-Tandem’s size is an advantage for smaller contractors, but its durability is a plus for even the largest jobs,” Derichs said. The system is available in three color blends with a natural chiseled stone appearance. For Constance Marina, the Margeaux Beige color was selected.
The Result
A Lasting Impression:
The Final Transformation
“We took an unattractive hillside and made it a functional, serviceable space with the unmatched look of natural chiseled stone,” said Landwehr, who purchased the property nine years ago for the location and functionality of the buildings. His renovations include a tiki bar already under development on a water barge at the marina, with future plans for a restaurant. “It’s a gorgeous wall. It looks great and gives the marina a finished look from the water,” Landwehr said.
While the aesthetic appeal of the wall is important, performance proved even more critical in 2015. After heavy snowfall from Winter Storm Thor, a rapid warmup on March 8 caused the Ohio River to flood, cresting approximately halfway up Constance Marina’s new gravity wall. Additional heavy rains followed, and the river eventually reached its highest level since 1997, completely submerging the wall except for the cap.
The water remained at this level for two days before receding. Marina owner David Landwehr monitored the wall throughout the flood event and until the water fully returned to the base of the wall.
During development of Mega-Tandem™, Belgard’s Research and Development division conducted extensive internal testing, and the team was proud to see the system perform during a real-world event. “Anytime you get into these types of applications with a new product, there is always an unknown factor until it’s tested in a real-life situation,” said Al Pfannenstein, National Retaining Wall Manager for Belgard. “Mega-Tandem was designed as a flood wall, and now we have solid evidence of its strength and durability in the field.”
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