Some 500 spills a year occur in the Prudhoe Bay oil fields and along the 800-mile, three-decade-old pipeline system.
When oil began flowing south from Alaska's North Slope to the port at Valdez nearly 30 years ago, it was a new era for US energy production and distribution. From the start, it was a technologically daring and politically controversial project. As evidenced by this week's shutdown of a portion of pipeline in the Prudhoe Bay oil field due to a spill, it remains so today.
Despite what industry supporters say are more environmentally friendly ways of detecting and extracting oil from the North Slope today, the means of transporting the liquid gold south is old and – critics say – becoming dangerously decrepit. In some places pipeline walls have lost as much as 80 percent of their thickness as a result of corrosion, industry officials say.
Meanwhile, environmental, economic, and legal fallout continues from the 1989 oil spill, which dumped at least 11 million gallons of oil onto 1,200 miles of shoreline in Prince William Sound after the tanker Exxon Valdez had filled up at the pipeline's southern terminal.
All of this adds urgency to the long-running debate over whether to allow drilling in the Arctic National Wildlife Refuge.
Though most oil pipelines in Alaska have exceeded their 25-year design life they're generally safe and secure, industry officials say. Corrosion expert Bill Hedges, who works for BP, the company whose pipeline recently sprung a leak, says many lines are in "excellent condition."
The corrosion detection and control program in the 800-mile Trans-Alaska Pipeline system (TAPS) is "world class," says BP America chief executive Bob Malone. The pipeline is operated by Alyeska Pipeline Service Co, which Mr. Malone used to head.
But at a news conference Monday in Anchorage, Alaska, BP officials acknowledged that the company's method of testing the thickness of Prudhoe Bay transit pipelines connecting to the trans-Alaska system had proved inadequate.
"Clearly, we are already in the process of adjusting considerably our corrosion program," said Steve Marshall, president of BP Exploration (Alaska).
The pipeline system presents major environmental and design challenges. It crosses more than 800 rivers and streams, three mountain ranges, and three major active faults. Three-quarters of it traverses fragile permafrost. It is built in zigzag fashion to allow for expansion and contraction during temperature changes as well as movement from possible earthquakes.