The company responsible for the biggest oil spill Alberta has seen in decades has finally apologized for its handling of the situation.

Plains Midstream Canada has been criticized for being slow to communicate about the situation but a week after the massive leak, the president of the organization offered an apology and maintained the company will make the situation "right".

"I apologize that we have not had more direct communication. Our efforts to date have been focused on containing and mitigating the impact of the release," said David Duckett, the president of Plains Midstream Canada.

"We will ensure that there's open, honest and timely communication with all affected parties," Duckett added.

Cleanup crews are scrambling to try to prevent any more damage after 28,000 barrels of oil spilled into a wetland near the Peace River, but one environmental expert contends the area will never be the same.

About one-fifth of the oil has been removed so far but there is no firm timeline on how long it will take to complete the cleanup, after a pipeline ruptured in the Peace River area a week ago.

Cleanup estimates range anywhere from two to eight months but Alberta Environment Minister Rob Renner acknowledges that could be optimistic.

"By the time revegetation is done and the area is restored, it could be substantially longer than that," said Renner, who plans to visit the region in the coming week.

The company contends most of the cleanup part of the operation can be completed in between two and four months.

But one environmental expert dismissed the idea the area can ever be restored.

"In terms of restoring it, not a chance," said David Schindler. "Wetlands of that sort are not restoreable, they take thousands of years to develop."

Schindler said the spill will continue to leave its mark on the landscape, serving as a reminder of the devastating spill.

"No matter how thorough the cleaning is, there will be occasions when oil slicks and perhaps tar balls appear on the surface of any water remaining in the area," said Schindler.

Company officials also said the cause of the leak has been determined.

"The pipeline was inadequately compacted, resulting in the break of the pipeline," said Stephen Bart, V.P. Operations with Plains Midstream.

The company has 150 people working on the cleanup, with crews working around the clock trying to mitigate the damage.

With files from CTV's Sonia Sunger.