Welding is a suspect in tank collapse in Chesapeake

CHESAPEAKE

In trying to unravel the mystery of the collapse of Allied Terminals Tank 201 in Chesapeake, experts say those investigating the failure will be trying to determine whether the liquid fertilizer corroded welds that held the massive tank together.

They also are likely to review major welding work that was done on the structure in late 2006.

Tank collapses are an extremely rare occurrence, experts say. But when any above ground liquid fertilizer tank has failed in recent years, investigators have determined that defective welding was the main cause, according to Environmental Protection Agency documents.

The collapse in Chesapeake on Nov. 12 appears to have been among the largest of its kind in recent history.

At 2:25 p.m. that day, the tank collapse spilled 2 million gallons of liquid fertilizer and injured two workers.

About 200,000 gallons of product remained unaccounted for after the cleanup. Some of it flowed into the Elizabeth River's Southern Branch, which could result in federal and state enforcement actions against Allied Terminals, officials say.

The Chesapeake Fire Marshal's Office and the federal Occupational Safety and Health Administration will be looking into the tank's collapse, officials say.

Allied Terminals is doing its own investigation. The company's executive vice president, Bruce Law, said it was too early to guess at any cause of the tank failure.

The key to the investigation, experts say, will be figuring out which part of the tank split to cause the collapse: one of the vertical welds that helped keep the tank together or one of the numerous steel plates that made up the tank's walls.

"If it was a weld that was split, the weld wasn't properly evaluated" in an inspection, said Gary G. Boley, a Norfolk-based engineer who has inspected more than 500 above ground liquid fertilizer tanks and thousands of fuel storage tanks. "If it was a split plate, they would never have seen that coming."

Executives with Allied Terminals are unsure about the age of Tank 201, which appeared in an aerial photograph from 1937.

But regulators say the tank's age is not necessarily a factor in its collapse. Portsmouth's Craney Island has fuel storage tanks that were built in 1917 or 1918, and "many of them have outlasted some of the newer tanks" built in the area, said Tom Madigan of the Virginia Department of Environmental Quality's petroleum storage tanks program. "It's unfair to characterize them by age alone," he said.

There have been few collapses of liquid fertilizer tanks in recent years.

In 1997, a 1-million-gallon liquid fertilizer tank in Iowa ruptured, according to EPA documents. Its walls fell onto two other tanks. A temporary dike prevented the spill from flowing into the Missouri River.

In Ohio in 2000, a tank collapsed and sent a wave of liquid fertilizer crashing through a concrete wall. More than 800,000 gallons spilled into the Ohio River. The force pushed two tractor-trailer rigs into the water as well.

In both of these cases, the tanks appeared to have had defective welds, the EPA documents say.

Boley, who is certified by the American Petroleum Institute and works for an environmental inspection services company called InterSpec LLC, said all major tank collapses can be attributed to one of three things: foundation settlement of the tank, corrosion or poor workmanship.

Tank 201 sits on property that was owned by an affiliate of Texaco before Allied Terminals took over the facility, located off Rosemont Avenue, in 2000, Law said. Previous owners used the tank to store petroleum products before Allied began to use it to store liquid fertilizer in March 2003, he said.

Liquid fertilizer weighs 70 to 80 percent more than gasoline, and that could have stressed the tank, Boley said. It was up to inspectors to determine how high the tank could safely be filled with the product.

The material, known as urea ammonium nitrate, or UAN, can also corrode or deteriorate welds or other pieces of the tank.

At Allied Terminals' Chesapeake facility in 2006, nearly 12,000 gallons of liquid fertilizer spilled from a 10-inch pressure relief line when a fitting corroded, according to a National Response Center report. Law said the spill was caused by using a pipe plug made of a material incompatible with the fertilizer and had nothing to do with Tank 201.

Still, the spill triggered a 2007 inspection by the EPA, which recommended that Allied develop a plan to evaluate how a change in stored liquids will affect the company's equipment and operations. Law said Allied did as the EPA asked.

The welding work done on Tank 201 in late 2006 was to upgrade the structure, which had no problems before then, Law said.

There are no required inspections for tanks storing liquid fertilizer, because it is not a flammable, combustible liquid. But Tank 201 passed an inspection in 2007 by an API-certified technician, Law said. It was visually inspected by a terminal operator on a daily basis, he said.

The two workers who were injured in the Nov. 12 collapse were reportedly doing welding work, Law said.

"To my knowledge, the work being accomplished had no relationship to the tank failure," he said.

Mike Saewitz, (757) 222-5207, mike.saewitz@pilotonline.com