Investigators are trying to determine what caused the Feb. 19 explosion of a TransCanada Corp. natural gas pipeline in a remote area of northern Ontario.

James Millar, a spokesman for the Calgary-based company, told NGI that Line 2 — one of three parallel lines comprising the Canadian Mainline — ruptured at 11:10 p.m. EST about two kilometers (1.24 miles) from the town of Beardmore, ON, 170 kilometers (105.6 miles) northeast of Thunder Bay, ON.

According to Millar Line 1 has been operational since the incident but Line 3 remained isolated late last week. The company was planning to have Line 3 back in service late in the day Saturday (Feb. 26). Millar said Line 3 was not damaged by the explosion and gas shipments were not been disrupted.

“We’re still trying to get a road built in the area, that’s how remote it is,” Millar said. “We’ve been working on the road since [last] Monday. We have been on site since Monday afternoon along with [investigators from] the National Energy Board and the Canadian Transportation Safety Board. We’re expecting them to release the site to us any day so we can begin repairs and then of course the investigation will continue in conjunction with repairs.”

Millar said the 1.5-kilometer (.93-mile) road would be used to bring in heavy equipment to repair the damaged Line 2. “It’s taking a few days because of the remoteness of the area,” he said. “It’s swampy and there are also some steep hills that we’ve had to navigate.”

The cause of the explosion is still under investigation.

On the day of the explosion, “There were some people who voluntarily left their homes, but there was no official evacuation,” said Millar. “They returned to their homes in about an hour. There was no danger to the public [and] nobody was injured.”

According to Millar, workers at the TransCanada’s gas control center in Calgary detected a drop in pressure and were able to remotely shut down valves on both sides of the rupture — creating a segment 28 kilometers (17.4 miles) long — within five minutes. He said the fire at the explosion site burned off residual gas in the segment through the night and finally ended Feb. 20 at about 8:45 a.m.

TransCanada’s Canadian Mainline, which runs about 14,000 kilometers (8,700 miles) from Alberta to Quebec, has a daily capacity of 7 Bcf, but the average amount shipped daily in 2010 was around 3.4 Bcf/d, according to Millar. He said the section of pipeline that exploded was constructed in 1972, and the three lines in that area run parallel about 35 to 50 feet apart and two feet below ground.

The Feb. 19 explosion is the fourth major natural gas pipeline rupture in North America since September, and the TransCanada rupture could add to growing concerns about the age of the natural gas pipeline infrastructure in the U.S. and help advance pipeline safety legislation through Congress. One bill, S 275, was introduced earlier this month by U.S. Sens. Frank Lautenberg (D-NJ) and Jay Rockefeller (D-VA) (see NGI, Feb. 21).

On Sept. 10 eight people were killed and 35 homes were destroyed in San Bruno, CA after the explosion of a Pacific Gas & Electric pipeline (see NGI, Nov. 8, 2010; Sept. 13, 2010). Five people were killed when an underground gas line owned by utility UGI Corp. exploded in Allentown, PA on Feb. 9 (see NGI, Feb. 21; Feb. 14a). A segment of the 36-inch diameter Tennessee Gas Pipeline, owned and operated by El Paso Corp., exploded on Feb. 10 and caused a fire near Dungannon, OH. There were no injuries (see NGI, Feb. 14b).

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