* U.S. environmental agency categorizes pipe rupture as
* Exxon shuts Pegasus pipeline after thousands of barrels
* Twenty-two homes evacuated
* Second spill in the United States involving crude from
Canada this week
By Matthew Robinson and David Sheppard
NEW YORK, March 30 Exxon Mobil was
working to clean up thousands of barrels of oil in Mayflower,
Arkansas, after a pipeline carrying heavy Canadian crude
ruptured, a major spill likely to stoke debate over transporting
Canada's oil to the United States.
Exxon shut the Pegasus pipeline, which can carry more than
90,000 barrels per day (bpd) of crude oil from Pakota, Illinois,
to Nederland, Texas, after the leak was discovered on Friday
afternoon, the company said in a statement.
Exxon, hit with a $1.7 million fine by regulators this week
over a 2011 spill in the Yellowstone River, said a few thousand
barrels of oil had been observed.
A company spokesman confirmed the line was carrying Canadian
Wabasca Heavy crude. That grade is a heavy bitumen crude diluted
with lighter liquids to allow it to flow through pipelines,
according to the Canadian Energy Pipeline Association (CEPA),
which referred to Wabasca as "oil sands" in a report.
The spill occurred as the U.S. State Department is
considering the fate of the 800,000 bpd Keystone XL pipeline,
which would carry crude from Canada's oil sands to the Gulf
Coast. Environmentalists, concerned about the impact of
developing the oil sands, have sought to block its approval.
Supporters say Keystone will help bring down the cost of
fuel in the United States.
The Arkansas spill was the second incident this week where
Canadian crude has spilled in the United States. On Wednesday, a
train carrying Canadian crude derailed in Minnesota, spilling
15,000 gallons of oil.
Exxon expanded the Pegasus pipeline in 2009 to carry more
Canadian crude from the Midwest to the Gulf Coast refining hub
and installed what it called new "leak detection technology".
Exxon said federal, state and local officials were on site
and the company said it was staging a response for a spill of
more than 10,000 barrels "to be conservative". Clean-up crews
had recovered approximately 4,500 barrels of oil and water.
"The air quality does not likely present a human health
risk, with the exception of the high pooling areas, where
clean-up crews are working with safety equipment," Exxon said in
U.S. media said the spill was in a subdivision. Mayflower
city police said the oil had not reached Lake Conway nearby.
The U.S. Environmental Protection Agency categorized the
rupture as a "major spill," Exxon said, and 22 homes were
evacuated following the incident.
A spokesman for the Department of Transportation confirmed
that an inspector from the Pipeline and Hazardous Materials
Safety Administration had been sent to the scene to determine
what caused the failure. The Environmental Protection Agency is
the federal on-scene coordinator for the spill.
Some environmentalists argue that oil sands crudes are more
corrosive than conventional oil, although a CEPA report, put
together by oil and gas consultancy Penspen, argued diluted
bitumen is no more corrosive than other heavy crude.
The U.S. Department of Transportation earlier this week
proposed a fine of 1.7 million for Exxon over pipeline safety
violations relating to a 2011 oil spill in the Yellowstone
River. Exxon's Silvertip pipeline, which carries 40,000 barrels
per day of crude in Montana, leaked about 1,500 barrels of oil
into the river in July 2011 after heavy flooding in the area.
In 1989, the Exxon Valdez supertanker struck a reef in
Prince William Sound off Alaska and spilled 250,000 barrels of