When the Mississippi River topped the Yazoo-Mississippi Delta levee in Tunica, Miss., the Fitzgerald Casino was one of several resorts inundated.
Portadam Inc., based in Williamstown, N.J., has been manufacturing temporary cofferdam systems since 1981. While contractors along the Eastern seaboard appreciate the portable system’s functionality, company CEO Bob Gatta said the versatile structure wasn’t well known elsewhere.
The Army Corps of Engineers changed that by purchasing 8,000 linear ft. (2,438 m) of 5-ft. (1.5 m) high units for flood control. With sections stationed across the country for rapid deployment to emergency sites, the secret is out about the benefits of this fully reusable modular system.
In June 2011, when spring rains and heavy snowmelt caused the Missouri River to breach the levee in Parkville, Mo., the Corps dispatched 1,600 linear ft. (487 m) of the system to hold back floodwater.
Although the Corps doesn’t endorse any product, results from a 2004 test conducted at the Engineering Research and Development Center in Vicksburg, Miss., at the request of Congress ranked Portadam first, based on speed and ease of installation and removal and because it’s 100 percent reusable.
Initially developed in 1974 through a British government grant, the system includes a flexible waterproof membrane made of nylon-reinforced PVC material attached to a welded tubular steel frame. When one job is done, it can be power-washed and reused. Strong enough to absorb demolition blasts during bridge construction, the rugged fabric passed ACE impact studies, rendering it capable of withstanding debris-laden flood surges. In addition, Gatta noted, the non-porous material stops rips from propagating, meaning it won’t fail if the liner is punctured.
Environmentally friendly, it doesn’t trap contamination. Another advantage is that “everything that goes in the water comes back out,” Gatta said. Sheet piling can leave metal fragments behind. Sandbags can leak; conversely, they can leach toxins from floodwaters, complicating their disposal.
Fargo, N.D., annually uses 1 to 3 million sandbags to fight flooding along the Red River. Messy and labor-intensive, they were largely replaced this year by 1,600 linear ft. of Portadam sent by the Corps to extend the levee. Portadam required less manpower and only 20 hours to install.
Similarly, when the Mississippi River topped the Yazoo-Mississippi Delta levee in Tunica, Miss., the Fitzgerald Casino was one of several resorts inundated. A call to Portadam resulted in 2,100 linear ft. (640 m) of the cofferdam system delivered three days later. A crew of 20 installed it in a day.
Speed of installation makes the Portadam system an appealing option. Because it doesn’t penetrate the sub-surface, installation is quicker and removal is easier. Both are completed without heavy equipment. As a result, it’s typically one-half to two-thirds the cost of sheet piling.
Cost is one thing; accessibility is another.
“It can go places where sheet piling can’t,” Gatta explained. It adapts to any soil type and is suitable for slopes. Since it rests atop the sub-surface, Portadam doesn’t create turbidity like other methods of containment.
Gatta described it as a time-proven product that minimizes the risks of cofferdamming. Originally designed for the construction industry, its value as emergency flood control is becoming well known.