(Recasts with documents from engineering firm, quote from regulator)
By Mike De Souza
FORT MCMURRAY, Alberta, July 22 (Reuters) - Infrastructure at the site in northern Alberta of one of the biggest oil-related pipeline spills ever on North American soil was installed on a "tight schedule", according to the firm that developed some of the pipeline's safety technology.
The engineering firm, French-based ITP Interpipe, said in a June 2014 presentation to the Society of Petroleum Engineers in Calgary that field work at the site at Nexen Energy's Long Lake oil sands facility, where the spill occurred, was completed in less than 12 months.
The pipeline's leak detection systems failed, and it could have been leaking for weeks before the spill was detected on July 15 by a contractor walking along the line.
On a media tour of the spill site on Wednesday, executives from Nexen, owned by China's CNOOC Ltd, said the project was not rushed.
Nexen's senior vice president, Canadian operations, Ron Bailey, said the company's safety practices had been strengthened since the CNOOC takeover in 2013.
"This is not about a rush job," Bailey said. "This is not about cuts or anything like that. This is an unfortunate accident. We're going to get to the bottom of that."
Nexen said it would likely take months to find the root cause of the leak, which released more than 31,500 barrels of emulsion, a mixture of bitumen, water and sand.
Bailey said the leak likely occurred after June 29, when the pipeline was cleaned with water.
The incident dealt another blow to Canada's oil sands industry in northern Alberta, which is under fire from environmental groups for its carbon-intensive production process.
The ITP employee who delivered the 2014 presentation about the pipeline's technology confirmed that the firm provided the double-wall thermal insulation and other heat-tracing engineering on the pipeline.
"However ITP was not in charge of the steel pipes supply, nor of the design and supply of the leak detection system, nor of the pipeline engineering, installation or operating," ITP said in an e-mailed statement.
A manager at the Alberta Energy Regulator, Colin Woods, said it approved the project but did not do a construction inspection on the line since it was not considered to be at risk. He confirmed that the technology was new and not commonly used.
Bailey said Nexen is putting a high priority on cleaning up the spill and investigating its cause and will not restart the nearby Kinosis oil sands project until the spill's cause is clear and the site cleaned.
With additional writing by Jeffrey Hodgson; Editing by Peter Galloway