Canada's federal pipeline regulator has ordered Enbridge to conduct a full engineering assessment of a troubled northern pipeline that has sprung several leaks in the last two months.

The National Energy Board issued the demand on March after Enbridge reported finding four oil leaks on its Norman Wells to Zama pipeline (Line 21) in a two month period this year. All occurred along the same segment of the line that experienced a major oil spill in 2011.

In response to the order, Herb Norwegian, Dehcho First Nations Grand Chief, called for the replacement of the entire 870-kilometre line before a catastrophic eruption occurs affecting a major waterway.

"We need to actually call for the replacement of the entire line and put something better in there because this is too dangerous," Norwegian told the Northern News Service last month. "We're going to be dealing with something serious later on if we don't deal with the problem."

Built in 1985 on challenging and difficult terrain similar to the proposed Northern Gateway project, Line 21 was designed to carry 50,000 barrels of crude a day from Norman Wells to Alberta.

In recent years the pipeline has carried about 35,000 barrels a day, but pumped loads of controversy. Both Enbridge's and the board's response to the 2011 spill and its implications about the line's integrity have frustrated First Nation communities along its route.

Two years ago aboriginal hunters found a pool of crude in the forest along the line. Enbridge then reported that a small leak had occurred.

The problem eventually turned out to be a significant 1,500 barrel spill due to a crack on a girth weld.

After Enbridge repaired the leak with a pressure containing sleeve, the NEB ordered to the company to reduce pressure in the line and increase fly-over pipeline inspections.*

Norwegian told the Northern News Service last month that Enbridge's piecemeal approach to repairing leaks was no longer adequate or responsible.

"It's gotten to the point now where they're taking this Band-Aid approach and putting a Band-Aid on this garden hose that's not fit to deal with the environment," said Norwegian. "Putting these patches is not good enough. They have to deal with the bigger problem."

The NEB has also ordered Enbridge to review its leak detection systems.

At a recent Senate hearing, Gaetan Caron, NEB chair and CEO, admitted that the board had not communicated well with northern communities about leaks on Line 21, and that "it is difficult to respond to emergencies in the Northwest Territories."

Ever since an Enbridge pipeline ruptured and released 20,000 barrels of diluted bitumen in Michigan, the largest onshore oil spill in U.S. history, the company has been under intense public scrutiny.

U.S. regulators found a "culture of deviance" on safety issues at the Calgary-based firm.

Veteran energy reporter Andrew Nikiforuk is a contributing editor to The Tyee.

*Incorrect paragraph removed.