Safety System Glitch Forces Evac

Tuesday, April 5, 2016 @ 05:04 PM gHale


A malfunctioning safety system in a trailer led to a natural gas leak that prompted evacuations Saturday morning in Milton, VT.

The gas was leaking from a trailer at NG Advantage’s facility, which was the third related incident at the facility in three years.

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No injuries or damage resulted from the incident, which began at 7:30 a.m. and largely had ended three hours later. NG Advantage said blame for what happened likely lay with a malfunctioning safety system on the trailer.

The site is in an industrial area in Milton.

Milton Fire Chief Don Turner said the trailer appeared to have released a full load of 350,000 cubic feet of natural gas. The same trailer caused one of the previous leaks at the site, he said, though a company official was later unable to confirm the trailer’s maintenance history.

Once the leak began, Turner said, emergency officials wanted to allow the trailer to vent the full contents, as designed, so the gas can dissipate in the air.

“There was no threat of explosion at any time,” Turner said.

The wind was shifting during the morning, but the major arteries of I-89 and U.S. 7 remained open. Crews ended up stationed on the roads to take readings of the gas levels. Traffic was allowed to keep flowing on the interstate because the wind direction mostly was pushing the gas in the opposite direction, according to a firefighter on the scene.

The decision to shut down the highway would be made in collaboration between Fire Chief Turner and the Vermont State Police, said state police spokesman Scott Waterman. The ultimate decision was the fire chief’s.

Tom Evslin, chairman and chief executive of natural gas supplier, NG Advantage, said it’s likely the safety system on the trailer, which releases gas in case of a fire, had malfunctioned.

“Sometimes the safety systems get overprotective, and they vent the gas,” Evslin said.

Natural gas dissipates quickly, he said, because it is lighter than air.

The smell associated with natural gas is a chemical additive, and the white cloud that formed at the leak Saturday contained ice crystals associated with the depressurization of gas.

“I’m sure the evacuation was an excess of caution,” Evslin said. “There’s no indication that anybody was in real danger.”

The NG Advantage facility in Milton has had three similar incidents since opening in March 2013, Evslin said. The Milton Fire Department has training and experience in natural gas response.

“When natural gas is handled carefully, it’s very, very safe,” Evslin said.

The Vermont State HazMat Response Team ended up consulted but was not asked to respond, said Mark Bosma, a spokesman for Vermont Emergency Management.