Pegasus ruptured in late March. Exxon said it was preparing to pull the damaged section out of the ground for inspection after receiving a corrective action order from federal pipeline regulation authorities. The cause of the incident remains under investigation.
Pegasus can carry Canadian crude oil, a type considered more toxic to the environmental than conventional crude oil. Advocacy group Tar Sands Blockade said it sent its own correspondents to the area, who speculated that oil from the pipeline found its way into nearby wetlands via storm drains.
Exxon said an estimated 27,000 barrels of an oil-water mixture were recovered from the area. Around 5,000 barrels of oil were spilled from the Pegasus pipeline, though Exxon said a final volume would be determined once the pipeline was repaired and refilled.
The company said drinking water supplies weren't contaminated by the spill and air quality standards were within safe levels.
The late March spill comes ahead of a U.S. State Department meeting next week on the planned Keystone XL pipeline, designed for Canadian crude. Critics say Canadian crude is more corrosive than conventional crude oil.
Pegasus was built in the 1940s.