A third leak has been discovered along the Norman Wells Pipeline.

Enbridge said it discovered contaminated soil in two spots along the pipeline west of Fort Simpson, N.W.T., last month. The pipeline company said the leaks were discovered because of a new program it's using that allows workers to look for small amounts of oil.

These are not large free flowing spills, it said. The company said they are releases of oil from the pipeline into the ground and so far they've been easily contained.

Pehdzeh Ki Contractors has been hired by Enbridge to bring the contaminated soil in dump trucks to a landfill in Fort Nelson, B.C.

One of the contaminated sites is about 120 kilometres west of Fort Simpson. The second is around 60 kilometers west of the community. The 869 kilometre pipeline runs from Norman Wells to northern Alberta.

Brad Enge with Pehdzeh Ki Contractors thinks an excavator came into contact with a pipe.

"The pipeline was shut down when they were doing the digs of course, so there might have been some residual crude in the pipeline that leaked out into the ground," Enge said.

"They dug up all of the ground and probably took about four times more soil than they really needed."

Enbridge’s Graham White said it can't confirm what caused the leak.

"We don't know. That's part of an investigation and a part of the information that we gather when we are doing our maintenance and repairs and that will come out in our investigation and that of the regulators," he said.

Both the National Energy Board and the Transportation Safety Board are involved in the investigation. So far, there haven't been any reports of damage to wildlife or water.

Enbridge has added sleeves to the areas where the leaks happened to prevent any more oil from leaking out. It is also updating the National Energy Board daily on the status of the cleanup.