BP Plc suspects that extensive ice plugs in one of its Alaskan pipelines caused the line to split, spilling approximately 46 000 gallons of oil and water mixture onto the snowy tundra.
Steve Rinehart, spokesman for BP, has said that from its own investigations, BP is attributing the leak to a pressure build-up due to ice plugs. 'From visual inspection, it looks like it was caused by overpressure inside the pipeline…we think that that overpressure was linked to the ice they found in the pipeline'.
On Monday, BP found a 2 ft crack in a flowline that serves its Lisburne field. The crack is thought to have caused the leak that was discovered on 29th November.
BP had shut down the pipeline a few weeks before the leak was discovered, suspecting ice plugs on the line. A BP analysis over the last few days suggests that there was ice blockage on either side of the point of rupture, with a space of about 1300 ft between, Rinehart said.
State officials are conducting a separate investigation and have yet to conclude what caused the pipeline to rupture. The state’s probe will likely include an investigation of why ice built up in the line. Tom DeRuyter, the Alaska Department of Environmental Conservation Manager who is the on-scene co-ordinator for spill response, has said that the pipeline rupture is 'the biggest hole I’ve ever seen'.
BP is already on probation for spilling more than 200 000 gallons from a Prudhoe Bay pipeline in 2006.
Cleanup of the Lisburne spill site continues, and BP oil production in Alaska remains unaffected.