MONTREAL -- It's a controversial project that pits the economic interests against environmental ones.

Calgary-based energy giant Enbridge Inc. is making a case before the National Energy Board in Montreal this week to reverse the flow of oil on the Line 9 pipeline and increase its capacity.

“So that it flows from Hamilton to Montreal so that it can bring western Canadian crude to refineries in Quebec,” said Graham White, manager of business communications at Enbridge Inc. at the hearing Tuesday in Montreal.

Enbridge is making its case for the project, while insisting safety is its top priority, while others suggest it could put communities at risk.

Dimitri Tsingakis of the Industrial Association of East-End Montreal, represents refinery companies in the area. He advocated before the NEB to reverse the flow of Line 9 for several reasons.

For one, he said, it's less expensive to receive crude oil from home soil than from overseas.

“Obviously it will help the companies be more efficient and have more economic benefits,” he said.

Secondly, it will keep jobs local, he argued.

“Basically, Line 9 reversal is going to help us maintain whatever companies are left and help them be competitive within the North American and world markets,” he said.

But at what cost?

Environmental groups like Equiterre argue they're concerned about the environmental impact, especially since they say the company plans to transport oil from Alberta's tar sands.

“Producing tar sands emits two to three times more greenhouse gas emissions that conventional oil. Tar sands also have a huge impact on the quality of water and now more and more studies are coming out to support that,” said Sidney Ribeaux of Equiterre, who also worries about leaks.

Enbridge is still cleaning up after a massive spill in a Michigan river in 2010.

Enbridge said Lessons have been learned and tools are in place to ensure safety. For example, the 831-kilometre-long line is continuously monitored from a control centre in Edmonton. If an irregular reading comes in, the line can be shut down within minutes.

“We can do that within three to ten minutes. We can stop that pressure on the line and even if you look at a very rare incident, a large incident, and our large incidents are very rare, in those situations the stopping of flow of line stops the leak,” said White.

Hearings continue in Montreal until Thursday, then move onto Toronto. A decision from the National Energy Board is expected sometime in 2014.