signs of a gas leak
Signs of a natural gas pipeline leak, from the Interstate Natural Gas Association of America:
•Whistling or hissing sound
•Distinctive, strong odor, often compared to rotten eggs (from a chemical added to otherwise odorless natural gas)
•Dense fog, mist or white cloud
•Bubbling in water ponds or creeks
•Dust or dirt blowing up from the ground
•Discolored or dead vegetation above the pipeline right of way.
MOUNT VERNON — When the natural gas pipeline in Morgan County exploded recently, destroying two homes, it immediately raised fears: Could it happen here? There are interstate transmission lines in Knox County. Who owns them and are they properly maintained?
The cause of the Morgan County blast has not yet been determined. Matt Butler, a spokesman for the Public Utilities Commission of Ohio, said the failed section of the line was excavated and sent to a metallurgical lab in Dublin for testing and analysis.
Meanwhile, the Pipeline and Hazardous Materials Safety Administration of the U.S. Department of Transportation has ordered Tennessee Gas Pipeline to reduce the pressure in the line to 80 percent of normal and obtain approval from PHMSA before returning the line to service.
“Inline inspections and aerial patrols are used in conjunction with other tools to ensure the safety and reliability of our pipeline systems,” said a spokeswoman with Tennessee Gas Pipeline, in reports after the explosion. “Both the June 2011 inline inspection and the aerial patrol on Nov. 11, 2011, did not show any indication that the pipeline was not operating as it should.”
The transmission lines in Knox County belong to NiSource Gas Transmission and Storage (formerly Columbia Gas Transmission Co.). A multiple main line, consisting of a 20-inch and a 16-inch line, runs north from the vicinity of Homer, veering to the east to pass between Mount Vernon and Gambier. The 20-inch line continues north through Monroe and Pike townships, while the 16-inch main line branches off in the vicinity of Gambier and runs northeast. Another 20-inch main line runs northwest from Homer through Milford Township. A secondary line also runs off of this, extending approximately from Centerburg to Bangs. Other secondary lines extend from a junction with the main line southeast of Mount Vernon up to the vicinity of Fredericktown and from the junction east to Millwood. (The map can be viewed using the PHMSA map viewer at www.npms.phsma.dot.gov)
Nationally, there are 300,000 miles of inter- and intrastate transmission lines and 2.1 million miles of smaller distribution lines owned by local distribution companies.
The line that exploded in Morgan County was a 30-inch transmission line.
“There’s no guarantee an explosion (like the one in Morgan County) couldn’t happen somewhere else,” Butler said, “But we have a comprehensive pipeline safety program.”
The PUCO does not have jurisdiction over interstate pipelines, but is an agent for enforcing PHMSA regulations. They make sure inspections are done and spot-check them.
“It’s more of an audit function,” Butler said. “The operator is responsible for inspections. Federal requirements are for inspections every two years; we check the paperwork and do spot checks in the field to verify inspections are accurate.”