More than a quarter of the nearly 2,000 miles of natural gas pipelines maintained by two companies in South Carolina were installed in the 1950s, making them the same age of the deadly pipeline that exploded in California a week ago.
South Carolina Electric & Gas Co. has 105 miles of gas pipelines dating back to the 1950s, and Carolina Gas Transmission maintains 432 miles of gas pipelines that are that old, according to SCE&G spokesman Eric Boomhower.
Both companies, subsidiaries of Cayce-based Scana Corp., have 1,920 miles of gas transmission lines.
While the age of the ruptured steel pipe in California garnered the focus of attention, the cause of the blast near San Francisco that killed six people and destroyed nearly 40 homes remains under investigation.
Boomhower said the two companies use steel pipes, but emphasized that proper maintenance and ongoing inspections can extend pipelines' lives indefinitely.
Age could be a factor in some pipelines, according to Carl Weimer, executive director of the Pipeline Safety Trust.
"Older pipelines are much more at risk because we didn't have the protective technology that we do now," Weimer said. "Old pipes had either no corrosion protection or were wrapped with material that looked like tar paper."
In metro Charleston, SCE&G has 28 miles of gas transmission pipeline running through sections identified as high consequence areas. The designation has nothing to do with the safety of pipelines and was created nationally to put the greatest emphasis on the most populous regions.
Boomhower declined to disclose the location of the lines, citing security reasons, but he pointed out that markers placed along gas pipeline corridors are there to alert people who might be digging in the area. Carolina Gas
Transmission has no gas transmissions lines in the Charleston area.
Boomhower also said both companies meet all federal requirements related to inspections, and control centers monitor gas flows and pressures around the clock.
The federal Pipeline and Hazardous Materials Safety Administration requires all gas transmission pipelines in high consequence areas to be inspected at least once every seven years, Boomhower said. He added that both companies employ varying methods of inspections more regularly.
"We follow rigorous inspection and testing schedules for all equipment and safety devices," Boomhower said. "As an additional safety measure, we add an odorant to our natural gas to help with the detection of any potential leaks. Employee safety, public safety and system integrity take precedent over any other aspects of our business."
CGT also use devices called "smart pigs" that run through sections of pipe, deploying sensors and cameras to detect cracks, corrosion and other defects from inside a line.
Crews from both companies also walk the entire pipeline at least once a year -- and in some instances twice a year -- using an instrument designed to detect leaks, Boomhower said. Also, both companies use aerial patrols over gas transmission lines, SCE&G monthly and CGT quarterly.
Both companies annually mail out notices to homes and businesses within 1,000 feet of gas transmission and distribution lines as a reminder.
The ruptured California pipeline dated back to 1956, before suburbia was built on top of it. The pipe was inspected twice in the past year for corrosion and leaks and turned up no problems, according to Pacific Gas & Electric Co.
Boomhowever said signs of a possible natural gas leak include a rotten-egg odor; discolored or dead vegetation over or near the pipeline; a hissing, whistling or roaring sound near a gas appliance or the pipeline; dirt or debris being blown into the air; persistent bubbles in streams, ponds or wet areas; and flames if a leak has ignited.
On Wednesday, the Obama administration announced a need for tighter oversight of the nation's pipelines and higher penalties for some safety violations.
Legislation sent to Congress Wednesday would increase from $1 million to $2.5 million the maximum fine for the most serious pipeline violations involving deaths, injuries or major environmental harm, the Department of Transportation said.
It also would pay for an additional 40 inspectors and safety regulators over the next four years.