A USA Today Network study of the nation’s aging infrastructure of gas lines published this week showed that destructive blasts of aging lines have cost $2 billion in damages since 2004.

The root cost of most blasts is aging iron pipes, the study concluded. Iron gas pipes came into use in the United States in the 1870s and continued well into the 20th century. The problem is that iron degrades and softens over time. Iron represents about 2 percent of all the gas mains in the United States, but is involved in 11 percent of the worse gas leaks.

The research showed that there are at least 85,000 miles of aging cast-iron and bare-steel gas pipes being used in the country, and more than 800 miles of those pipes are in Alabama.

But they don’t belong to the Southeast Alabama Gas District.

“Our cast iron lines have been replaced,” Shannon Jackson, spokeswoman for SEAGD, said.

“In 2012, the gas district completed a multi-year project to replace all the cast iron in our system.”

SEAGD is owned by 14 municipalities, and each is represented on the company’s board.

“When we decided to replace the lines years ago, there wasn’t any mandated law or requirement by the feds,” Jackson said. “We just knew the system was old, and this type pipe had recurring issues nationally caused by corrosion.

The board was very proactive years ago to let us start the process.”

The project was completed two years ago, she said.

“We completed this about two years ago,” she said. “We are able to say all of ours have been removed from our system.”

Jackson said SEAGD, like other utilities, is required to have a distribution integrity management plan, which includes inspection.

“We are constantly looking at our lines,” she said. “We have employees who only patrol pipeline system and check for leaks. That’s all they do.”

Like many other utilities, SEAGD’s biggest damage threat is from third-party damages. The company sends a constant marketing message to “call before you dig.”

“Of course, all of our lines are underground,” she said. “But so many other lines are, too. Electric lines and fiber optics are there.”

While it is important for contractors to call the free hotline – by dialing 811 – before digging, it also can be important for individuals.

“My mailbox is on a right-of-way,” Jackson said, adding that those who dig for small projects also should call 811 to make sure the dig is safe.