ANCHORAGE (AP) -- As much as 20,000 gallons of drilling material was spilled at BP's offshore Northstar oil development.
The spill came after a containment barrier collapsed Tuesday, allowing the drilling mud to flow across a portion of the man-made island in the Beaufort Sea.
None of the drilling mud reached the water, state officials say.
BP Exploration (Alaska) said the mud was contained inside snow berms within several hours of the spill.
The barrier collapsed at 1:45 p.m. State environmental officials were contacted about the accident at 5 p.m.
Kurt Fredrikkson, state deputy commissioner of Environmental Conservation, said he was concerned about how long it took BP to notify the state.
''They have our phone numbers. This is something we're going to talk to them about,'' Fredrikkson told the Anchorage Daily News. ''With Northstar, the sooner the better.''
Northstar is a 149 million-barrel oil prospect six miles off the Arctic coast. The development has been troubled by questions about the safety of its subsea pipeline, its rising costs and problems meeting oil spill clean-up standards.
BP hopes to begin producing oil from the field late this year.
Drilling began at the site in December.
Drilling muds are injected down wells during drilling to lubricate the bit and remove rock, sand and other material cut from the well bore.
Once in operation, BP will dispose of used drilling mud by injecting it back into the ground. But the company does not yet have approval to use an injection well, forcing it to store used mud in surface containment pens, spokesman Paul Laird said.
The spilled mud will be taken to Prudhoe Bay for injection underground, Laird said. The company expects to complete clean up within three days and resume drilling within seven days.
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