RENEE MONTAGNE, host:
Operators of Alaska's giant Prudhoe Bay oil field are scrambling to inspect pipelines for signs of corrosion as they try to decide whether it's safe to keep pumping oil from some portion of the field.
BP has already shut down about half of Prudhoe Bay after discovering a small oil spill last weekend. About 630 gallons of crude oil had leaked.
NPR's Scott Horsley has this report.
SCOTT HORSLEY reporting:
The spill that threatens to shut down North America's largest oil field is not large - about 15 barrels in all - here on the eastern end of Prudhoe Bay. Workers in Hazmat suits have contained the oil in an area about one-fourth the size of a football field. They're now running a sponge-like material through the ground to soak the oil from the grassy tundra.
Amanda Stark(ph) of the State Department of Environmental Conservation is the on-scene coordinator for the clean up.
Ms. AMANDA STARK (State Department of Environmental Conservation): This is a relatively small spill and it was contained very quickly. There were folks that discovered it and we captured a large portion of the spill material in these fold-a-tanks(ph).
HORSLEY: Nevertheless, the spill came as a shock to BP and the company quickly shut down the eastern half of Prudhoe Bay, which had been pumping some 200,000 barrels of oil a day.
Survey crews are now racing to inspect pipes on the western half of the field to see if that can stay open.
(Soundbite of knocking on pipe)
HORSLEY: The pipeline is coated with insulation some four inches thick. Once that's cut away, workers spread a gel on the underbelly of the pipe, then use a device like a sonogram to see how thick the walls are.
Notations every foot along the side of the pipe show the readings workers have already taken. BP's Gary Crawford(ph) says the numbers show both the original thickness of the pipe and how much is remaining.
Mr. GARY CRAWFORD (British Petroleum): So there's 20/1000s of an inch that they've detected at at least one location that has been corroded away. That's fairly minimal.
HORSLEY: BP will be studying this data over the weekend as it decides whether it has to close the western half of the oil field. The state of Alaska has a lot riding on BP's decision.
Governor Frank Murkowski toured the area yesterday. He says the shut-down of the eastern half is already costing his state more than $3 million a day.
Governor FRANK MURKOWSKI (Republican, Alaska): It's not in the interest of BP to have shut this field down. It's not in the interest of the state. It's not in the interest of the American people. But it's also a recognition of what reality's all about. Because this equipment, obviously, wore out faster than they figured it would and the question is why.
HORSLEY: That's the question BP and regulators have been asking since a larger oil spill in March. Both that line and the one that failed last weekend are called oil transit lines - sort of liquid side streets that feed into the highway that is the Trans-Alaskan Pipelines.
As production in Prudhoe Bay has slowed, so has the flow of oil in those transit lines. BP officials theorize that may have allowed bacteria to collect in the bottom of the pipes causing the corrosion.
BP didn't worry about that when the oil was moving faster. Field manager Kent Cokeland(ph) says, in hindsight, the company wasn't careful enough.
Mr. KENT COKELAND (Field Manager, British Petroleum): Any time that we have a surprise like this it tells us that there were some gaps or some inadequacies in the program that we had. So our primary objective is to make changes in the future that eliminate the possibility of having a recurrence of this.
HORSLEY: Whether or not BP decides it's safe to keep using this pipe in the short-run, long-term plans call for replacing 16 miles of oil transit pipeline. That's a big job. Some of the pipe that's already been ordered isn't set for delivery until December.
Construction is actually easier in the wintertime when work crews can move across the ice to some of the least accessible parts of the pipeline. Still, one executive says, productivity does suffer when the temperature falls to 60 degrees below zero.
Scott Horsley, NPR News, Prudhoe Bay, Alaska.