Enbridge Energy said Monday that it wants to build a second major crude oil pipeline across northern Minnesota, replacing a 1960s-era line that has ruptured repeatedly.

The Calgary-based pipeline company also asked state regulators to reconsider their recent order that stretches out by a year the review of its other crude-oil pipeline project — the proposed Sandpiper line to carry North Dakota oil across Minnesota.

In the latest project, Enbridge said it intends to replace an entire pipeline, known as Line 3, carrying Canadian oil from Alberta to an oil-storage terminal in Superior, Wis. The pipeline operates at reduced capacity because of long-standing concerns about its integrity.

The company asked the Minnesota Public Utilities Commission to approve its plans to contact landowners near the 338-mile-long corridor, the first step in a regulatory review that will take at least a year.

Many affected landowners are aware of the Line 3 project, which Enbridge announced in March. Its path would mostly parallel the proposed Sandpiper pipeline from Clearbrook, where two oil terminals are located, then run south toward Park Rapids, and east to Superior, Wis., site of another oil terminal and pipeline connections to various Midwest refineries.

Lorraine Little, a spokeswoman for Enbridge, said the company has been talking to property owners whose lands are needed for both pipelines. She said more than 90 percent of the Sandpiper property easements and more than 50 percent of the new Line 3 easements have been successfully negotiated with affected landowners, who get a bonus for signing early.

"The replacement of this pipeline is about safety," Little said in an interview.

Enbridge decided to replace Line 3 rather than repair the 34-inch-diameter pipe because that would require digging in about 900 places where tests revealed problems. The pipeline suffers from corrosion because the protective tape on the steel has not held up, Little said.

The project is expected to face opposition from environmental groups, including climate activists who are fighting pipelines like TransCanada's proposed Keystone XL in western states as a way to slow development of Alberta's tar sands.

"It traverses some of the most important lake country, aquifers and water resources in Minnesota," said Richard Smith, president of the Friends of the Headwaters, an environmental group based in Park Rapids that wants the Sandpiper and Line 3 to avoid the headwaters of the Mississippi River. "That is why we have advocated a different route."

Some of the state's worst pipeline accidents have happened on the existing Line 3, including a record 1991 spill of 1.7 million gallons of crude oil at Grand Rapids and an explosion and fire during a 2007 repair job that killed two workers. After a 2002 rupture near Cohasset, the National Transportation Safety Board identified a "pre-existing fatigue crack" in a pipe seam that suggested improper handling when pipe segments were shipped to the project decades ago.

Also Monday, the Minnesota Petroleum Marketers Association announced that a poll found that 55 percent of likely Minnesota voters favored the construction of oil pipelines in the state to reduce rail congestion and oil trains. The poll of 500 people was taken by Robert Blizzard and Public Opinion Strategies. They asked about the proposed Sandpiper pipeline, not specifically about Line 3.

The existing Line 3 pipeline carries Canadian crude oil from Alberta to Superior, Wis., crossing northern Minnesota on a path through or near the cities of Clearbrook, Bemidji, Grand Rapids and Cloquet. Enbridge said that line would be decommissioned after the new pipeline is built in 2017.

The new Line 3 will be a 36-inch diameter pipe, Enbridge said. The entire project, including a longer Canadian segment, is projected to cost $7.5 billion and Enbridge says it's the largest project in company history. The U.S. portion, mostly in Minnesota, is estimated at $2.3 billion.

In September, the PUC ordered studies of proposed alternate routes to carry crude oil across the state from west to east. State environmental agencies and interest groups that suggested the alternatives have raised concern about the concentration of pipelines through the lakes regions.

This Thursday, at the request of Enbridge, the PUC will reconsider its August decision to analyze one of the Sandpiper alternatives that the company says would be longer and more expensive.

David Shaffer • 612-673-7090