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Natural gas leak caused home blast

FARGO, N.D. - A leaky natural gas pipe blamed for a Sept. 2 house explosion in south Fargo was the same kind involved in a blast three years ago in Cottage Grove, Minn., which prompted Minnesota to launch a program with Xcel Energy to replace the pipe throughout the state by 2010.

Utilities have known about the pipe's potential risks since 1999, when the federal government issued a bulletin warning that pipe manufactured by Century Utility Products Inc. from 1970 to 1973 "may fail in service due to its poor resistance to brittle-like cracking."

Xcel says that of the 626 miles of plastic distribution pipelines in North Dakota, about 2 percent were manufactured by Century.

The utility estimates that less than 3 percent of the more than 44,000 service lines to homes and businesses in the state contain Century pipe.

"Presently, Xcel Energy has not made a determination to replace Century pipe in North Dakota," Xcel said Friday in an e-mailed response to questions by The Forum.

The underground pipe serving the Fargo twin home unit that exploded at 2215 15th St. S. was manufactured by Century in 1972, according to Xcel's incident report to the U.S. Pipeline and Hazardous Materials Safety Administration.

The report cites a material defect in the pipe as the apparent cause of the incident.

A leak the size of a pinhole was found in the service line 18 inches below ground, Xcel said in a written statement.

"Gas migrated into the building and was ignited by an unknown source," the report said. "A determination as to the cause of the leak cannot be made without additional testing."

The 1999 federal bulletin warned that the pipe "is prone to relatively short life when subjected to high local stress concentration."

Properly installed Century pipe that isn't under a lot of stress may not be at risk, officials said.

"It appears there's always something else that needs to be put into the equation for this pipe to fail," said Patrick Fahn, utility analyst with the North Dakota Public Service Commission.

"I wouldn't say that just having that pipe is a hazard," said Elizabeth Skalnek, chief engineer for the Minnesota Office of Pipeline Safety.

The U.S. Department of Transportation issued an advisory bulletin in 1999 after investigating a number of incidents, including a 1979 house explosion in Tuscola, Ill., and a 1994 fatal explosion at a bar in Waterloo, Iowa.

The Century pipe involved in the Tuscola blast failed after less than eight years in service, and the Waterloo pipe failed within 23 years.

Utilities were advised to closely monitor Century pipe for leaks and conduct more frequent leak surveys, which involves traveling over gas lines - either on foot or in a vehicle - with a gas detector and sniffing for gas.

"Remedial action, including replacement, should be taken to protect system integrity and public safety," the bulletin said.

Xcel said it performs annual leak surveys on Century mains and every three years on services to homes and businesses. Service lines installed between 1971 and 1976 may include Century pipe, the utility said.

"We are confident that our natural gas system is operating safely," Xcel said. "Our ongoing maintenance work includes numerous procedures to ensure this."

Iowa's two regulated utility companies voluntarily agreed to find and replace the faulty Century pipe in their systems, said Rob Hillesland, spokesman for the Iowa Utilities Board. The process was completed in 1999.

"It didn't require any pressure from the IUB for this to be accomplished swiftly in Iowa," he said in an e-mail.

Xcel agreed to replace Century pipe in Minnesota after a house explosion in the St. Paul suburb of Cottage Grove on Oct. 4, 2005.

The explosion bears several similarities to the Fargo blast. Both happened during storms, and both were first reported as lightning strikes.

In the Cottage Grove case, a husband and wife were in their basement and suffered burns when the house exploded.

The blast leveled the house and garage, scattering debris 50 feet away, according to the pipeline safety office's report.

An investigation found that gas leaking from a 1½-inch plastic main under the driveway migrated into the home, built to an explosive level and was ignited by an undetermined source. A rock impinging on the wall of the pipe caused the crack to develop, the report said.

The gas main was manufactured by Century and installed in 1976 by Northern States Power, which now does business as Xcel Energy.

In the Fargo incident, a relative of the most seriously injured victim, Luul Omar, 27, initially said she went down to the basement to check out a gas smell just before the blast.

Omar later reported she wasn't in the basement when the blast occurred but had been looking for shoes by a closet on the ground floor, her brother Abdi Omar told The Forum.

Two adults and three children were injured in the blast. Only Luul Omar remains hospitalized for severe burns.

Philip Sieff, the Minneapolis attorney representing the Omar family, said he hadn't seen Xcel's report and declined to comment.

Replacing pipe

Following the Cottage Grove explosion, Xcel agreed to replace Century pipe in Minnesota - including 112 miles of natural gas main and an estimated 7,486 service lines - by 2010, according to Skalnek and the utility.

Xcel felt the amount of pipe was small enough to replace in a short period of time with costs not too burdensome to its customers, who ultimately will foot the bill, she said.

Fahn, the North Dakota utilities analyst, said if Xcel followed federal guidelines for pipeline safety, it won't face penalties for the Fargo explosion. But the PSC could recommend changes to the utility's operations, he said.

In a recent e-mail about the investigation, Kevin Hanson, assistant director of the commission's testing and safety division, wrote that he spoke to a Minnesota official about that state's Century pipe replacement program.

"I think we are going to recommendation (sic) some form of replacement program also as a remedial action," Hanson wrote in the e-mail, sent to PSC officials Oct. 2 and later obtained by The Forum.

Asked if the PSC can force Xcel to replace Century pipe in North Dakota, Fahn said, "We'd need to know the cost. There's a lot of stuff to weigh in on that."

In some states, regulators who have tried to force utility companies to replace cast-iron pipes or other outdated infrastructure have faced opposition from advocacy groups who argue that low-income residents won't be able to afford the rate hikes that accompany such utility upgrades, Skalnek said.

"These pipe replacement programs that happen are very, very costly and time consuming," she said.

North Dakota doesn't seem to be having a lot of gas leaks because of Century pipe, Fahn said, adding a records inspection will reveal whether that's indeed the case.

If Century pipe leaks turn out to be common, "I don't think (Xcel) is going to hesitate to recommend something," Fahn said.