In 1968 oil was found in the Prudhoe Bay area, lots of oil, 25 billion barrels, making it the largest discovery in the USA and the 18th largest field in the world. Besides the challenge how to pump it out of the ground, another challenge was how to transport it out of Alaska to the lower 48. With the Prudhoe oil fields (locally known as “the North Slope”) located on the Arctic Ocean, shipping it straight out was not the most obvious choice. The plan was developed to build a pipeline to the ice free port of Valdez, 1286 km to the south, at the Prince William Sound.
After major opposition from conservationists and Alaska Native groups, the Alaska Native Claims Settlement Act (1971) calmed everybody down. There was land set aside for the Natives, for National Parks and Reserves, for oil exploitation and for the pipe line.
And in 1973 the oil companies with exploration rights (BP, ExxonMobile, ConocoPhillips) forming the Alyeska Pipeline Service Company started to design and build the pipeline.
And so the technical challenge started.
Mountain ranges
The problem: How to transport the oil through the pipeline as it is crossing 3 big mountain ranges, the Brook range in the far north, the Alaska Range with Denali as its highest point in the middle, and the Chugach mountains with all its glaciers in the south.
The solution: 11 pump stations are spread along the length of the pipe line to slow down or speed up the oil flow through the mountains.
Permafrost
The problem: From north of the Chugach range to more or less the Arctic Circle, the ground consist of discontinuous permafrost and further north there is even continuous permafrost. Burying the pipeline which transport 50C oil would melt the permafrost causes the pipeline to sink.
The solution: The pipeline is elevated above ground. Where the pipeline must be buried to cross a road, the line is situated in an active refrigerated ditch.
But the problem continues, the vertical beams holding up the pipeline can even melt the permafrost, and are therefore equipped with an ammonia based heat pipe inside and a heat exchanger on top.
Temperatures
The problem: With temperatures ranges from -40C to 25C the thermal expansion of the pipeline is a big concern.
The solution: Placing the pipeline on shoes and laying out a zig-zag path allows horizontal and lateral movement.
Denali Fault line
The problem: The line crosses the unstable Denali Fault line.
The solution: Place the pipeline on long sliders.
With all technical challenges covered, the pipeline started operating in 1977 and Alaska had a new source of income, oil instead of gold.
Project closed.
I love all this technical nerdy stuff and spend hrs reading all the information displays along the road, but what about the environment? Do we not all remember the ExxonValdez oil spill in 1989, when 40 million liters of oil were spilled in the beautiful Prince William Sound. Shouldn’t we all protect the wildest part of the wildest state? Its time to check it out myself, I am heading north.
Dag,
Iris (Fairbanks, 7797 miles)
