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Floating island may be unique solution to cleaning up overgrown pond

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Posted: Monday, August 27, 2012 7:57 am | Updated: 8:04 am, Mon Aug 27, 2012.

A unique solution was discovered for small pond choked by duckweed at a school off Highway 88 in Lodi.

It’s a floating island with a natural mechanism to starve unwanted weeds, and a lucky find for Linda Norgard at North Valley School. The island is the first of its kind in the world. If it does the job well, similar projects could enter ponds and reservoirs near and far.

The duckweed has been a problem for about four years, and health commission officials made it clear the pond needed a solution.

Norgard, maintenance supervisor for the school, found Floating Islands West online.

“It sounded like something that would work out here,” she said.

The pond is the final stage of a wastewater treatment plant for the school. Once all the solid wastes are removed, the water fills a holding pond until it evaporates. Over time, it filled up with determined duckweed that blocked the sunlight from the water, preventing evaporation.

“The kids thought it was solid, like a golf green,” said Norgard. On Friday, it looked like a massive mold puddle with unseemly brown spots.

Laddie Flock, CEO of Floating Islands West, thought an idea he and other have tinkered with for years could be the solution.

A standard floating island places sod or planting mix on top of a layer of recycled plastic. The plastic is spun into a dense mesh strong enough to support many times its own weight, and still allows plant roots to grow through it. The islands grow weeds, grasses and native plants that offer habitat while pulling nitrates out of the water. Without nitrates to feed on, the duckweed can’t grow.

In most household and industrial ponds, some kind of herbicide is used to keep water clear. But residue from those chemicals stays in the water and can return in unexpected ways, said Flock. Installing a floating island works at least 85 percent as well as an herbicide and removes those chemicals from the equation, he said.

The island installed on Friday is a little different. It will not grow plants on top. Instead, it will breed microbes to eat up the nitrates and other particles that duckweed needs to survive. Once the island has a chance to grow enough microbes, there won’t be enough food for the duckweed to grow. What remains in the water will shrivel, die off and fall to the bottom.

From the surface, it looks like two bunches of enthusiastic weeds are anchored to a plastic base. Instead, three floating islands are tethered together to breed microbes and starve out pesky duckweed.

The large central island weighs 736 pounds and measures seven feet by eight feet. Two vegetative islands on either side measure two feet by five feet. The island is flanked by two pairs of plastic pipes for buoyancy.

“It’s an island on steroids,” said Flock.

Hefting the massive island was no simple trick. The Leviathan was lifted in a harness by a forklift and driven to the side of the pond. Four workers each took hold of a cable attached to the island and stood on either side of the forklift to steady it in place. A few rocks were removed from the ponds border so the forklift could move close enough to the edge. From there, the island was gently lowered and floating on its own. From there, another worker climbed out on top of the island to secure it to two smaller standard islands.

But how does a floating box made of plastic and chrome breed hungry bacteria?

The island has an air diffuser at one end continuously pumping air into the system. That air gets water moving through the empty channel in the heart of the island, and brings whatever microbes might already exist in the water in contact with the plastic mesh mats. Microbes like plastic, says Flock.

“The plastic just sits there, but it has lots of space for the green stuff to grow,” he said. Once the microbes get in the plastic, they set up camp and breed prolifically. Microbes also breed on standard islands, but the air flow in the Leviathan speeds up the process.

Flock emphasized the island doesn’t kill the algae and duckweed.

“It’s not going to do anything except one thing: starve the duckweed of the food it needs to grow,” he said.

Floating islands were developed 12 to 13 years ago by a Montana fisherman named Bruce Kania, who noticed that fish tend to gather under floating islands where there’s lots of food. He developed a way to make his own islands to attract fish to more convenient river and lake fishing spots.

Flock met Kania six years ago while running Natural Rock Formations, a company that made art pieces out of rock. A client wanted a floating island incorporated in his design, and Flock didn’t know what that was. He connected with Kania online, they traded ideas, and eventually Flock joined his company.

“We’ve dreamed of having a machine to do this better,” said Flock. “We don’t know how well this will work.”

Contact reporter Sara Jane Pohlman at sarap@lodinews.com.

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1 comment:

  • Jackson Scott posted at 8:41 am on Mon, Aug 27, 2012.

    Jackson Scott Posts: 382

    Interesting... a quick google search shows several companies building islands. All sites stated the same basic thing: duckweed will not be totally removed/killed, the island's microbes will compete with the duckweed for nutrients. I look forward to a followup article on the progress of the island.



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