Depending on one’s perspective this can be a dark cloud or a silver lining, but there has been no overall change in the number of oil spills in Alaska from 1995 through 2009.
“The number of spills each year is neither increasing nor decreasing,” said Larry Dietrick, director of Alaska’s Department of Environmental Conservation’s (DEC) spill response division.
DEC did the $1.6 million study following spills from North Slope field pipelines in 2006 and 2009, and in 2010 on the Trans-Alaska Pipeline System, to see if there was a trend of increasing spills perhaps related to aging pipeline infrastructure, Dietrick said.
Data does suggest an increase in frequency of spills of more than 1,000 gallons, “but this is not conclusive. It bears further attention,” Dietrick said.
The study did indicate a greater number of spills related to older infrastructure, he said, and spills linked to in-field flow lines that carry mixtures of crude oil, water and natural gas from wells to petroleum processing facilities, Dietrick said. The combination of oil, water and gas can be highly corrosive.
Corrosion was the most common cause of spills of more than 1,000 gallons.
“Spills related to corrosion are relatively infrequent but their damage is often severe,” Dietrick said. “Still, there was no significant trend in the frequency or severity of corrosion-related spills.”
The state still plans to tighten its regulations on in-field flow lines. Dietrick said Alaska is the only state regulating in-field flow lines that carry unseparated oil, water and gas. Pipelines carrying crude oil after processing undergo regulation by a federal pipeline safety agency, he said.
Dietrick said DEC will propose amendments to regulations on flow lines in the next few months.
Among other changes, the agency will require producers to report on the condition of flow lines and piping within processing facilities.
Most likely there will be some sort of grading system of pipelines and facilities based on wall loss due to corrosion. DEC likely will tie into the pipeline integrity system used by the federal government, the Pipeline and Hazardous Materials Safety Administration, which sets 80 percent of wall loss as the point where a pipeline can no longer operate, Dietrick said.
That is the point where some remedial action, such as repairs, start up.
An annual report will benchmark performance of oil pipelines in the state against the 1995 to 2009 baseline data.
“We’ll want to show whether we’re up or down in any given year against the 15-year average,” he said.
DEC’s goal over time will be to tighten its requirements so there is a decline in the number of spills against the 15-year average.
DEC also will begin an evaluation for technologies that can detect small leaks around pipelines and facilities. Existing leak-detection systems installed on pipelines monitor changes in pressure and volume but are mainly effective with large spills.
“Every spill that has been reported has been detected by people, not the leak detection systems,” mainly because the spills were small and below the detection threshold, Dietrick said.

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