The U.S. Environmental Protection Agency has ordered Enbridge back to the site of the largest onshore oil spill in U.S. history to clean up remaining pools of bitumen in the Kalamazoo River.

Despite an unprecedented $800-million two year clean-up of one million gallons of oil (200,000 gallons more than Enbridge reported spilled), the EPA is still finding submerged bitumen contaminating a 38 mile stretch of the Kalamazoo River.

The beleaguered proponent of the controversial Northern Gateway project has ten days to respond or to submit work plans to clean up the remaining bitumen contamination.

According to the EPA submerged oil and/or oil-contaminated sediment is still generating an oil sheen on the river or whenever globules are disturbed by motor boat engines.

The rupture, which has sparked a national debate about pipeline safety, was the result of gross negligence. It actually took the company 17 hours to identify the toxic leak which poisoned several hundred people.

The National Transportation Safety Board found that Enbridge's 2010 pipeline rupture in Michigan was totally preventable. It also lambasted Enbridge for its "culture of deviance" on pipeline safety, and criticized the performance of weak regulators.

Once the pipeline ruptured the company failed to respond to the emergency with either adequate manpower or proper spill containment methods. Much of the bitumen, a heavy oil, sank to the bottom of the river while the condensate evaporated into the air making hundreds of people sick.

Instead of concentrating at the source of its spill, initial responders used booms nearly eight miles downstream. As a result more oil contaminated more wetlands and waterways, resulting in a $800 million clean-up or "five times more costly than any other accident."

At the beginning of the emergency Enbridge also used the wrong spill technology at the wrong place and at the wrong time. "It did not have adequate response on site." Nor did local responders have access to Enbridge's response plans.

Due to a series of repeated errors in the company's Edmonton-based pipeline control room the NTSB described the entire disaster an example of an "organizational accident" due to "team performance breakdown."

After the $800-million clean-up, pipeline lobbyists claimed that Enbridge had scrubbed and polished the Kalamazoo river so thoroughly that the company had left river cleaner than before the spill.

Enbridge press releases claim that the company has beefed up its pipeline integrity programs and “placed a renewed emphasis on the safety of our overall system.”

Calgary-based journalist Andrew Nikiforuk is a regular contributor to The Tyee on energy issues.