Source of costly corrosion stumps officials

By Stephen Tait , Staff Writer

Daily News of Newburyport

NEWBURYPORT - Whatever this mysterious force is, it started about two or three years ago, city officials say.

It is powerful enough that it stripped the steel off the pilings at the boardwalk and is eating through the steel sheeting of the bulkhead that supports the popular walkway at a much faster pace than officials expected. It is exposing the cement inside the pilings enough to shear three in half and require that another 17 need immediate repair.

And David Vine, a marine engineer, said once holes are made in the bulkhead sheetings underneath the boardwalk, the fill inside will begin to wash out.

The most popular theory for the corrosion, according to Vine and Geordie Vining, the city's public projects manager, is an electric current coming from somewhere in the Merrimack River. The source could be a power cable running underwater that replaced an electric tower, the relatively new power hookups on the boardwalk, or the increased number of large ships docking there.

"It is really just speculation at this point," Vining said. "It is likely to be something within the immediate area. I think we definitely need to investigate the shore power that the city installed, as well as the boats that tie up to the central waterfront. Those are the most obvious possible sources."

Whatever the source of the electric current, it is not strong enough to shock or injury anyone who might swim in the river or touch the water, Vining said. It simply provides the correct chemical balance of positive and negative ions to erode steel.

It is a problem seen in harbors worldwide.

"This type of electrical current in the water is a common occurrence when it comes to corrosion of steel in a marine environments," Vining said.

Indeed, one local man says the problem and fix are detailed in a paper written by the American Society of Civil Engineers.

Bob Folsom, a retired mechanical engineer, says the corrosion is natural "Galvanic" action that is essentially a chemical reaction creating an electric current. Folsom of Newburyport said that spells out a quick fix.

The Charles Street resident said all the city would have to do is attach a piece of "sacrificial" zinc to the pilings to save the steel. The corrosion, he said, would eat away at the zinc without hurting the piling.

"That way they don't have to keep re-welding," he said. "They just have to replace the zinc. Depending on how active (the corrosion) is, it could last a year or four to five years."

The City Council voted this week to spend $72,000 to fix 24 pilings on the boardwalk to help ensure the popular boating season in the city is not interrupted. Part of that money is $8,750 for a corrosion specialist to inspect the area, figure out what is causing the corrosion and help stop it.

Vining said the specialist should be able to either pinpoint where the electrical current is coming from or find out what else may be causing the corrosion.

"Its hard for us to know until we hire a specialist for the study," he said.

Folsom feels the city doesn't have to spend thousands of dollars for a study.

"It's already been done," Folsom said. "Information is readily available. Why go spend money? The sake of spending money, I guess."

Bill Schutt, a corrosion engineer who works for Matcor Inc., a company that works on corrosion worldwide, said he doesn't think there is an electrical current in the water.

"If you put those pilings in that sea water, they are going to corrode," he said. "It happens all over the place."

The company he works for installs a device that sends an electrical current to underwater steel and coats it with hydrogen molecules. The process is called cathodic protection.

"When you put the system on, no corrosion occurs," he said. "It is stalled."

Vining said the city has conducted visual and ultrasonic inspections of the pilings in 2001 and 2005. They observed the steel thinning, "which is sort of an expected life cycle of the steel," he said.

Now, though, the steel is gone or extremely thin on all the pilings about a foot under the average low-water mark, suggesting that some other force is at work rather than simply a natural phenomenon.

"When we started to look, people said the steel is completely gone on the pilings," Vining said. "The first reaction was disbelief. 'How could that be? Maybe somebody was seeing it wrong.'"

It is unclear when the accelerated corrosion started, but because of the inspections in prior years, it seems likely it started in the past two or three years.

At the City Council meeting this week, a councilor suggested it could possibly be from a huge power line buried underneath the river in recent years that spanned from Newburyport to Salisbury.

The shore power, which boats that dock at the central waterfront use, was installed with a renovation of the boardwalk in 2002, about five years ago.

"We are at a very different place than what we expected to be," Vining said. "It was certainly surprising. I think it was surprising for everybody."

Related links about Corrosion Prevention Jetty Piles:

• Corrosion Survey on Jetties
• Splash Zone Protection Jetty Piles
• Cathodic Protection Jetties
• Internal Corrosion Jetty Piles