Drop Anchor

An LSU professor has proposed that we should look into a system developed by a Dutch architect as way to mitigate the flooding in SE Louisiana.

Elizabeth English, who is affiliated with the Louisiana State University Hurricane Center, hopes to borrow an idea from the Dutch, who use "buoyant foundations" in some flood-prone communities to reduce flood damage.

In effect, the system works like a floating dock. When flooding occurs, the house is lifted above the water by flotation blocks beneath the home. The house settles to ground level when the flooding recedes. The concept, she said, is designed especially for wood-frame homes, such as the shotguns common in New Orleans. It would not work, at least as now conceived, for brick or concrete slab homes.

"I thought this could work in New Orleans," English said. "If the Dutch can do it, we should be able to do it in Louisiana."

A less sophisticated version has been used for years along some waterways in South Louisiana, she said.

The concept is relatively simple.

The flotation blocks, made of expanded polystyrene, commonly known as Styrofoam, are held together by steel frames and attached to the underside of a house, according to a description of her proposal. Four vertical guidance poles are attached not far from the corners of the house.

When flooding occurs, the flotation blocks lift the house.

Collars are attached around the poles to ensure that the house doesn't go anywhere but up when the water rises and down when it falls, English said. The homes would be strengthened with steel channels attached to the bottom beams to ensure they are strong enough to withstand being lifted and dropped.

But the concept is not without its hurdles.

Hilary Inyang, director of the Global Institute for Energy and Environmental Systems at the University of North Carolina at Charlotte, said English's proposal is a "more sophisticated version" of what many countries in flood-prone communities have used for decades.

"There are some practical difficulties with that concept, such as what you do about utilities that are generally tied in one place," Inyang said. "You'd have to make them more flexible. And you'd have to make sure that with these new foundations that you don't make these buildings more vulnerable to other environmental stresses, such as wind.

"So you'd want this done experimentally at first before you do it wholesale."

In her proposal, English talks about using "self-sealing breakaway connections for utility lines, or long, coiled umbilical lines that would allow electrical and telephone lines to move away from a home when it rises during a flood. Plumbing and sewage lines also can be designed to break away as needed, she said.

She estimated that building and installing the foundation would cost about $20,000. She conceded the figure is "very preliminary" based on estimates for the cost of materials and installation and experience building floating foundations along some Louisiana bayous.

But the difference between the Dutch designs and what Ms. English is proposing is that the Dutch intend their floating homes to be built over existing waterways whereas our homes would be built on dry land and float on the water when a flood does occur.

A simpler, and less expensive solution would be to merely raise existing houses or build new ones higher.

However, this does have some promise in areas where houses are built over water as the Dutch do. These would primarily be camps. And currently, there is no urgent need to rebuild them.