MARINE COATINGS

In the past few years, invasive fresh water mussels have been identified that threaten to disrupt marine commerce everywhere – and especially in the Great Lakes. With the invasion of these creatures, the longevity of any metal surface underwater such as steel sheet pilings have been reduced to just 50 percent of their intended life.

Dock owners all over the Great Lakes are faced with the costly replacement of steel sheet pilings in order to keep up with the demands of marine commerce.

However, there is another, less disruptive and less costly solution – Marine Coatings. It involves the application of Aquapure coating which can add decades of life to steel sheet pilings.

The process is relatively simple, requiring some very specialized equipment. The Marine Coatings company first cleans and prepares the surface by sandblasting. Once the face of the sheet metal is free of all corrosion, the Aquapure coating is applied using a two-part process involving heating the epoxy-based coating and spraying with an airless sprayer.

However, when the application process to steel sheet pilings happens in place – below the surface of the water – it requires not only specialized equipment, but also a great deal of innovation.

Marine Coating’s engineers designed and built coffer dams in order to work on steel sheet pilings in place, below the water’s surface. Two coffer dams work side-by-side, to hold back water pressure equaling 1,000 pounds per square foot against the coffer dam walls as well as approximately 100,000 pounds of uplift.

Once sealed against the sheet pilings and the water is extracted from the coffer dams, the application process of sandblasting and spraying happens like a leap frog game. The leap frogging is quick, because the drying time of Aquapure is only 10 minutes. And once dry, the surface is so tough, not even a torch can cut though it.

Dock owners find it to be an appealing and effective option to replacement of sheet pilings.

“Right now, coatings are our best remediation option for steel sheet piling in the harbor. It’s a good way to slow or even stop corrosion. Coatings usually run about 20% of the cost of replacing steel pilings and can buy dock owners 20 years of time,” said Chad Scott, a principal partner of AMI Consulting Engineers P.A. of Duluth.