THE TRANS-ALASKA PIPELINE SYSTEM
It was Thursday, 5 June 2008, when Nena and I finally saw the Trans-Alaska Pipeline System. What we saw was just
a short segment of the 800-mile (1,300 km) long pipeline system which runs north to south from the Arctic Ocean
at Prudhoe Bay, Alaska to the Gulf of Alaska at Valdez, Alaska. The pipeline system appeared to me like a giant
silver snake slithering across the rolling hills near the City of Fairbanks.
The Trans-Alaska Pipeline System (TAPS), usually called the Alyeska Pipeline in Alaska or the Alaska Pipeline
elsewhere, is a major U.S. oil pipeline connecting oil fields in northern Alaska to Valdez, a sea port, where
the oil can be shipped to the Lower 48 states for refining. Since its completion in 1977, the pipeline has
transported over 15 billion barrels (2.4 Tl) of oil.
Construction of the pipeline presented significant challenges due to the remoteness of the terrain and the
harshness of the environment it had to pass through. Between Arctic Alaska and Valdez, there were three mountain
ranges, active fault lines, miles of unstable, boggy ground underlain with frost, and migration paths of caribou
and moose. Geological activity has damaged the pipeline on several occasions.
It was built after oil was discovered at Prudhoe Bay (1968). The single 48 inch (1.22 m) diameter pipeline was
built between March 27, 1975 to May 31, 1977 at a cost of around US$8 billion. The pipe was constructed in six
sections by five different contractors employing 21,000 people at the peak of work. It was reported that 31
were killed in accidents during the construction of the pipeline.
The pipeline was built above ground in areas where thaw-sensitive permafrost exists. However, where the line
must be buried, such as highway crossings or avalanche-prone areas, the pipe is encased in an insulated,
refrigerated ditch. Nearby refrigeration plants pump cold brine through 6 inch (15 cm) pipes which absorb heat
and keep the soil cooled.
The pipeline route presented special challenges. As well as the harsh environment, the need to cross the
mountain ranges and many rivers and streams, the permafrost of Alaska meant that more than half of the pipeline's
length had to be elevated rather than buried as normal to prevent the ground melting and shifting. There were
five years of surveying and geological sampling before construction began.
The oil that flows from through the 48-inch diameter pipeline accounts for roughly 20 percent of U.S. oil
production annually. Along the pipeline there are eleven pump stations, each with four pumps. Each electric
pump is powered by diesel or natural gas generators.
The pipeline is surveyed several times a day, mostly by air. Due to the placement of the surveillance bases,
the pipeline can be surveyed in just two hours, but most surveys take longer to ensure thoroughness. Other
methods of surveying include regular Pipeline Inspection Gauges ("pigs"), sent through the line. Some pigs
are used to remove the buildup of paraffin inside the pipe, while others have electronics which relay radar
scans and fluid measurements as they travel.
The pipeline has been damaged several times. It was built with earthquakes in mind and has survived several,
including the 7.9 magnitude event of 7 November 2002. It is vulnerable to intentional attack and to forest
fires. The highest losses from the pipeline were in February 1978, when a deliberate explosion led to more
than 16,000 barrels (2,500 m³) leaking out at Steele Creek, near Fairbanks.
From 1977 to 1994 there were 30 to 40 spills a year on average. The worst years in terms of number of incidents
were 1991 to 1994, when there were 164 spills, although none were major. Since 1995 the number of spills has
been sharply reduced, with total losses from 1997 to 2000 totalling only 6.89 barrels (1.10 m³).
The steel pipe is resistant to gunshots, but on October 4, 2001, a drunken gunman named Daniel Carson Lewis
shot a hole into a weld near Livengood, causing a spill of about 6,000 barrels (950 m3). Approximately two
acres (20,000 m²) of tundra were soiled and were removed in the cleanup.
The pipeline was repaired and was restarted on October 7, 2001. Lewis, known as a troublemaker in the community
of fewer than 30 people, was apprehended four hours after the shooting. He was convicted on multiple state and
federal felony charges, including a $10,000 fine and 10-year federal sentence for being a felon in possession
of a firearm.
To view the photographs I took during our brief visit to a short segment of the Trans-Alaska Pipeline, just
click on the link shown below for the slideshow:
The Trans-Alaska Pipeline System
I hope the above brief write-up and the slideshow will give you a good idea about the Alaska Pipeline System.