CASPER, Wyo. — A former TransCanada engineer claims the company knew that its Bison natural gas pipeline in Wyoming had faults before it ruptured last year but ignored the problems in the rush to bring it online.
The Casper Star-Tribune reported Friday that Evan Vokes oversaw work on the pipeline and was terminated in May for undisclosed reasons. He told the newspaper that he saw problems with pipe alignment welding, excavation and backfilling. He said rocks were left in the pipeline’s ditch and they could have caused dents in the line.
“I sent (TransCanada) an email saying that they were in serious trouble,” he said. “It was a pretty rough show.”
A 60-foot section of the pipeline exploded on July 20, 2011, 20 miles northwest of Gillette, shaking the ground and spewing a brown cloud into the sky. The gas didn’t ignite. The pipeline, which runs across southeastern Montana into North Dakota, began operating in January 2011.
A spokesman for the Calgary-based company, Grady Semmens, said several tests done before failure didn’t show any problems but he said a hydrostatic test, in which water was pumped into the pipeline, may have further damaged the pipeline.
“We believe that the minor damage that occurred during backfilling may have grown as a result of the hydrostatic test and subsequent pressure cycles from initial loading of the line,” Semmens said. “This defect, which had otherwise eluded detection, caused the pipeline to fail.”
The U.S. Pipeline and Hazardous Materials Safety Administration is still investigating the rupture. The company will also soon be audited by Canadian regulators.
Semmens said that audit by the Canadian National Energy Board was previously planned but put on the fast track because of Vokes’ complaints, which have previously been reported by the Canadian Broadcasting Corporation.
TransCanada is seeking to build the controversial Keystone XL pipeline from western Canada to refineries along the Texas Gulf Coast.
The Bison pipeline primarily ships coal-bed methane from wells in the Powder River Basin and ties in with the Northern Border Pipeline in southwestern North Dakota.
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