It’s 26 feet tall, 53 feet wide, 800 feet long, weighs 140,000 pounds, is filled with water, and is probably pretty expensive; no, it’s not a sinking megayacht — it’s the world’s largest water-filled cofferdam by volume, as well as the longest, and it was just manufactured in Hydesville by Humboldt-based company AquaDam.

A definition: cofferdams are barriers built in bodies of water, allowing for the enclosed section to be drained, useful in a flood or during construction. This specimen, ordered to help future repairs on a levee in a wastewater treatment facility in Palm Harbor, Florida, was shipped out by AquaDam this morning, rolled up in a gigantic tube and lashed to a semi-truck. 

AquaDam’s cofferdams have some advantages over traditional cofferdams; because they’re water-inflated, they can be filled up with floodwater already at the site — in this case, about 6.4 million gallons of the stuff. Using one is a lot less labor-intensive than stacking sandbags or constructing a normal dam. Because they’re plastic, they’re also far cheaper; using sheet piling for the job this dam was created for would have cost around $15 million, said AquaDam manufacturing supervisor Seth Ash in a phone call with the Outpost today, but this dam cost about a tenth of that. 

“And when you’re done, you pump the water out,” Ash said. “You drag it out with an excavator, you roll it up as you’re dragging it out, and you can reuse it and reuse it and reuse it again.”

Working six days a week, 10 hours a day, it took three weeks to make. It’s made out of 700 panels, each 164 feet long, and just sewing them all together took a week of work. AquaDam has leveled up their manufacturing capabilities in the last decade; Ash said they never would have been able to make a dam this big 10 years ago, but purchasing a custom welder that allows them to weld their own plastic liners changed everything. 

“I think all our employees are pretty proud of being able to do this and to assemble this so quickly in a timely fashion,” Ash said. “And we had absolutely no problems doing this, assembly-wise or manufacturing-wise. It went really, really well. So I do believe most of our employees and our bosses are pretty happy about how well this went…I wish we would have put a wrap on the bag before it left here. It would have looked a little prettier. But, you know, maneuvering something that’s 140,000 pounds is easier said than done.”