| By FELICITY BARRINGER
WASHINGTON, March 14 - The largest oil spill to occur on the tundra of
Alaska's
North Slope has deposited up to 267,000
gallons of thick crude oil over two acres in the sprawling Prudhoe Bay
production facilities, forcing cleanup crews to work in temperatures far
below zero to vacuum and dig up the thick mixture of snow and oil.
The spill went undetected for as long as five days before an oilfield worker
detected the acrid scent of hydrocarbons while driving through the area on
March 2, Maureen Johnson, the senior vice president and manager of the
Prudhoe Bay unit for BP, said at a news conference in Anchorage on Tuesday.
At the conference, officials from BP, the company pumping the oil, and from
the Alaska Department of Environmental Conservation said they believed that
the oil had escaped through a pinprick-size hole in a corroded 34-inch pipe
leading to the Trans-Alaska Pipeline System.
The pressure of the leaking oil, they said, gradually expanded the hole to a
quarter- or half-inch wide. Most of the oil seeped beneath the snow without
attracting the attention of workers monitoring alarm systems.
The leak occurred in a section of pipe built in the late 1970's, in the
earliest days of oil production at Prudhoe Bay. The larger pipeline, which
carries North Slope oil across the state, was completed in 1977.
Environmental groups were quick to point out that the spill raises doubts
about the continuing reliability and durability of the infrastructure of
North Slope production.
The current spill is among the worst in the pipeline's history, and the
first of such a magnitude likely to be blamed on the decay of the aging
system. In 1989, about 11 million gallons fouled Prince William Sound after
the Exxon Valdez tanker ran aground. About 700,000 gallons escaped from the
pipeline after vandals blew up a section of it in 1978, and about 285,000
gallons spilled in 2001 when a hunter shot the pipeline.
Asked later on Tuesday about how company and state officials arrived at
their tentative conclusions about the cause of the spill, Ms. Johnson said
investigators had "looked at the leak investigation system, at all the logs
and all the charts" that measure oil volume and pressure at different times
and in different areas.
At the news conference, Ms. Johnson said that although routine inspections
last year indicated increasing corrosion in the pipe, the severity of
corrosion found since the leak pointed to a swift and sudden deterioration.
"We had no reason to expect" that this pipe, which carried 100,000 barrels
of oil to the Alaska pipeline a day, "was going to leak," she said.
Ms. Johnson also said the leak was "smaller than our system would detect,"
adding that it was "still not acceptable to BP."
The normal fluctuations of oil flow in this particular pipe could have
masked warning signals, state environment officials said.
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