CALGARY, Alberta (Reuters) - Enbridge Inc said a leaking pipeline in the Northwest Territories spilled as much as 1,500 barrels, drastically higher than its initial estimate of a four-barrel leak and the third major spill on the company's lines in less than 12 months.
The company said late on Monday that its initial forecast for the size of the spill on the Norman Wells line last month at a remote site 50 km (31 miles) south of Wrigley, Northwest Territories, was based on the amount of oil that collected on the surface. The company raised that estimate to 90 barrels earlier this month.
But further excavation found even more oil trapped under the surface. The company now says it expects between 700 and 1,500 barrels leaked from the line.
The spill is the latest in a series of such incidents that have plagued Canadian pipeline operators since last summer.
In late July, Enbridge's Line 6B ruptured and spilled more than 20,000 barrels of oil into a Michigan river system. The company also had an spill from its 670,000 Line 6A in Illinois while it was still repairing the first break.
Since then, TransCanada Corp, Kinder Morgan Energy Partners LP and Plains All American Pipeline LP have had do deal with spills on their lines carrying Canadian oil.
Though repairs were completed on May 20, the 39,400 bpd line, which takes crude from Imperial Oil Ltd's Norman Wells, N.W.T., oil field and connects with Plain's Rainbow pipeline at Zama in northwestern Alberta, has been shut since the Rainbow line ruptured on April 28, spilling 28,000 barrels.
Enbridge spokeswoman Gina Jordan said in an email that the company will be able to firm up its estimate on the spill's size as it completes excavation at the site.
Reporting by Scott Haggett; editing by Rob Wilson