Study finds oil transport firm knew of Mich. pipeline cracks

WASHINGTON -- Enbridge Inc. knew an oil pipeline in Michigan had corrosion and cracks at least five years before a 2010 spill, a U.S. safety board said Tuesday in a finding that an environmental group cited to fight shipments of oil from Canada.

The spill near Marshall, about 100 miles west of Detroit, has cost more than $800 million to clean up, making it the most costly U.S. onshore oil spill, Deborah Hersman, chairman of the National Transportation Safety Board, said Tuesday.

"In 2005, Enbridge detected the very defect that led to this failure -- located within a corrosion area that Enbridge had identified the year before," Ms. Hersman said. "Yet, for five years they did nothing to address the corrosion or cracking at the rupture site -- and the problem festered."

The failed pipeline stretches 293 miles from Griffith, Ind., to Sarnia, Ontario, and is a part of a network that starts in Edmonton, Alberta, and extends to the northern United States. The July 25, 2010, rupture spilled 20,082 barrels of oil into Talmadge Creek and eventually the Kalamazoo River. Almost 4,000 animals were affected and 320 people reported symptoms consistent with crude-oil exposure, Ms. Hersman said.

The Association of Oil Pipe Lines, a group representing the industry, said the three-year average of pipeline incidents fell 59 percent from 2001 to 2011, according to a statement issued Tuesday in Washington.