How safe are Southcentral gas pipelines?

Southcentral Alaska is heavily dependent on natural gas, especially during the winter, for heating buildings and generating electricity. But how durable are the pipelines that ship gas around the region, and what is the risk of a major pipeline failure and the resultant disruption to gas supplies?

On May 1 John Lau, director of engineering for Enstar Natural Gas Co., told the Anchorage Mayor’s Energy Task Force that although many of the Southcentral gas pipelines are now quite old they were all built using relatively modern technology, technology that should prevent a major pipeline failure of the type that has occurred elsewhere in the U.S. If there were to be a pipeline failure in Southcentral it would be a fixable leak rather than a catastrophic breach, he said.

Moreover, the pipelines are operated at pressures comfortably below their maximum allowable levels, while Cook Inlet pipeline gas contains almost no water and no corrosive hydrogen sulfide. Enstar has a “call before you dig” program to try to ensure that nobody inadvertently damages a buried pipeline. And, during the summer construction season, Enstar conducts aerial surveys, to monitor construction projects that involve excavations near pipelines, Lau said.

Enstar also has a modern computer-based system for monitoring pipeline pressures and flow rates, he said.

And between 2005 and 2012 Enstar conducted a comprehensive program mandated by the federal Pipeline and Hazardous Materials Safety Administration to determine the condition of its pipelines using pigs, the torpedo-shaped devices that pipeline operators send down the insides of pipelines, Lau said. The pigs can locate pipeline bends, kinks, dents or wall loss, he said.

—Alan Bailey