Enbridge Inc. is proposing to spend up to $500 million to change the design of its Northern Gateway pipeline in a bid to address safety concerns of aboriginal groups and others.

The project, which had a $5.5-billion price tag before Friday's announcement, has been the focus of intense debate among local communities, environmental groups and politicians.

Enbridge made its announcement on the same day the Alberta government — a staunch supporter of Northern Gateway — announced an independent pipeline safety review following three petroleum leaks in the province this year.

Critics of Northern Gateway, a paired system of oil and gas pipelines between the oilsands in northern Alberta and a terminal near Kitimat, B.C., have said they're worried about the potential environmental risks it poses within the B.C. Interior and in coastal waters. It's not a question of whether it leaks, but when, they worry.

Calgary-based Enbridge said Friday it had listened to the feedback from public hearings and was prepared to address concerns with a combination of improved technology and monitoring.

"We had already planned to build a state-of-the-art project using the most advanced technology, safety measures and procedures in the industry," said Janet Holder, executive vice-president for western access.

"These initiatives announced today make what we believe is a very safe project even safer."

Among other things, Enbridge said its new design would increase the thickness of pipe walls at river crossings. Enbridge said it would also increase the number of inspections it does by at least 50 per cent and staff pumping stations in remote locations around the clock.

"And after years of consultation with stakeholders and after personally attending many of the regulatory hearings for Northern Gateway, it has become clear to me that we have to do everything we can to ensure confidence in the project," Holder told reporters on a conference call.

Concerns over danger from oil tankers

The executive director of B.C. Coastal First Nations, a group that represents aboriginals on the province's central and northern coasts, said the announcement does nothing to alleviate its major concern — oil tankers.

"These tankers are still going to be going through the fourth most dangerous body of water in the world, and they still have the potential to wipe out everything on the cost of British Columbia with absolutely no benefits going to anybody in B.C.," Art Sterritt said.

Holder indicated Enbridge's plans for the marine terminal and tankers will remain unchanged.

In Calgary, meanwhile, Alberta Energy Minister Ken Hughes announced the province would tap an independent third party to work with the Energy Resources Conservation Board in reviewing pipeline integrity, the safety of pipe that crosses waterways and response to spills.

There have been three pipeline leaks in Alberta this year, including the leak of up to 475,000 litres of oil into the Red Deer River, a major drinking water source in central Alberta.

Earlier this month, the U.S. National Transportation Safety Board lambasted Enbridge for its handling of an oil spill in Michigan two years ago.

A report concluded Enbridge bungled its response when millions of litres of oil began to pour in and around the Kalamazoo River in July 2010, comparing the company's handling of the spill to the "Keystone Kops."

The Michigan spill affected more than 50 kilometres of waterways and wetlands and about 320 people reported symptoms from crude oil exposure.

The cleanup has cost Enbridge about $800 million.