Hearings begin on Wednesday in the Northwest Territories to examine the impact of a proposed natural gas pipeline through the Mackenzie Valley.

Technical aspects of the proposed 1,300-kilometre pipeline are to be discussed at the National Energy Board hearing.

Separate hearings on the environmental and social impact begin next month.

The National Energy Board will visit about 25 northern communities that could be affected by the line. Construction could begin in 2009.

A consortium led by Imperial Oil says it will spend $7 billion to build the pipeline along the Mackenzie River from the Beaufort Delta to Alberta, but stopped working on the project last spring.

At that time, the partners said they were looking for more progress on resolving critical areas such as the fees the companies would pay for access to aboriginal land in the Northwest Territories.

In 1977, an inquiry led by Justice Thomas Berger killed plans for a similar pipeline. His report recommended a 10-year moratorium on pipeline construction while native land claims are settled, and a permanent ban on any pipeline from Alaska across the northern Yukon.

The current proposal includes three of the four aboriginal groups in the Mackenzie Valley as part-owners of the pipeline with Imperial Oil.

"We have to find some way to get an economic base to become economically self-sufficient and come out from under dependency on government," said Fred Carmichael, head of the aboriginal pipeline group.

The current proposal is to bury the pipeline in the permafrost, and Carmichael, who grew up on a trapline, dismisses concerns that the project will harm the caribou and the land they roam.

His views are widely shared in Inuvik, but they'll face challenges by environmental organizations.

Paul Falvo, a Yellowknife-based lawyer for the Sierra Legal Defence Fund, is worried that clean-burning natural gas will be used to extract heavily polluting oil from the Alberta tarsands.

"There's of course the direct physical impact on the Mackenzie Valley, but there's a lot more than that because we have to consider the ultimate destination of the gas," he said.