The source of a sheen in the area of Unocal's Baker Platform on Cook Inlet is still a mystery, but agency and industry officials hope sample results expected late this week will solve it.
A commercial airline pilot first spotted the mile-long sheen July 31 in the area of two undersea pipelines abandoned by Amoco in 1984. The abandoned lines originally carried natural gas and crude oil from the Anna Platform, now owned by Unocal. State officials have cited them as the most likely source for the sheen and said state law makes both Unocal and Amoco, which was purchased by BP, potentially responsible.
Kevin Tabler, Unocal land and governmental affairs manager, said that neither the source of the sheen nor ownership and responsibility for the abandoned lines has yet been determined. However, the companies are working together to investigate the sheen. Since BP does not have the equipment in Cook Inlet, Unocal is taking the lead, he said. However, BP has sent several people to observe and assist.
"The issue of ownership and liability and responsibility we'll sort out after the fact," Tabler said.
About five barrels of oil seep naturally from the Cook Inlet seabed each day, he said, and the sheen could come from a natural seep.
Unocal sent a boat last week to survey the bottom in the area of the spill with side-scan sonar. State officials said the survey confirmed the presence to the abandoned pipelines and found no other likely sources for the sheen.
The gas line had been charged to a pressure of 57 pounds per square inch. On Aug. 3, Unocal bled the pressure down to about 11 pounds per square inch. Alaska Department of Environmental Conservation officials said that if the sheen disappeared, that would implicate the gas line as the source.
However, the sheen has not disappeared, Gary Folley, a DEC environmental specialist, said Friday.
Samples of the sheen were collected last week and sent to an Anchorage laboratory for analysis. However, the Anchorage lab could not process them, he said. So, they were sent to a laboratory in the Lower 48.
Tabler said that both of the lines were flushed and filled with sea water when Amoco abandoned them. Last week, Unocal collected samples of fluid from the gas line where it leaves the Anna Platform and where it comes ashore at the Unocal East Foreland production facility in Nikiski. Those have been sent to the same laboratory that is analyzing samples of the sheen, he said. The results should be available late this week.
If samples from the gas line don't match those from the sheen, Unocal will collect samples from the crude oil pipeline.
BP is working closely with Unocal to identify the source of the sheen, said BP spokesperson Paul Laird.
"At this point, we have reason to believe it's coming from one of those abandoned Amoco pipelines. We expect to confirm that later next week," Laird said Friday. "In the mean time, we're working with Unocal to develop a plan to address it."
Folley said that if the source proves to be one of the abandoned pipelines, the most likely fix is to use vacuum trucks on shore to suck all the fluids from the line.
"Then, the problem would be to figure out what to do with all that water," he said.
Unocal and BP are examining permits to determine whether contaminated water from one of the abandoned pipelines could be disposed of through an injection well or treated like produced water from an oil or gas well, he said. Tabler said there are several options under consideration.
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