Map of the pipeline

The Trans-Alaska Pipeline System (TAPS), sometimes called the Alyeska Pipeline or Alaska Pipeline, is a major U.S. oil pipeline connecting oil fields in northern Alaska to a sea port where the oil can be shipped to the Lower 48 states for refining.

Oil was discovered at Prudhoe Bay in 1968. A pipeline was considered the only viable system for transporting the oil to the nearest ice-free port, over 800 miles (1,280 km) away at Valdez. The oil companies with exploitation rights grouped together as the Alyeska consortium to create a company to design, build, and then operate the pipeline. US President Richard Nixon signed the Trans-Alaska Pipeline Authorization Act into law on November 16, 1973, which authorized the construction of the pipeline. Although the pipeline is actually about 799 miles long, it is usually referred to as 800 miles long.

The 799 mile route presented special challenges. As well as the harsh environment, the need to cross three mountain groups and many rivers and streams, the permafrost of Alaska meant that almost 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?

An elevated section

The single 48 inch (1.22 m) diameter pipeline was built between March 27, 1975 and 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; 31 were killed in accidents during construction. There are twelve pump stations, each with four pumps. Usually only around seven stations are active at one time.

Some parts of the pipeline have radiators that disperse heat from the oil. It emerges from the ground at up to 180° Fahrenheit (80° Celsius). Without the radiators, the heat could melt the permafrost, causing the pipeline to sink and possibly sustain damage.

Oil began flowing on June 20, 1977. Since then over 13 billion barrels (2 km³) have been pumped, peaking at 2.1 million barrels (330,000 m³) per day in 1988. Around 16,000 tankers have been loaded at the Marine Terminal at Valdez. The terminal has berths for four tankers and cost almost US$1.4 billion to build. The first tanker to leave the terminal was the ARCO Juneau on August 1, 1977.

The pipeline is surveyed several times a day, mostly by air. Due to the placement of the surveillance bases, the pipeline could be surveyed in just two hours.

The pipeline has been damaged on a number of occasions. Although it was built with earthquakes in mind, it is vulnerable to intentional attack and potentially to forest fires. The highest losses from the pipeline was in February 1979, when a deliberate explosion led to more than 16,000 barrels (2,500 m³) leaking out at Steele Creek, near Fairbanks. However, no one was charged. From 1977–1994 there were 30 to 40 spills a year on average, the worst years in terms of number of incidents were 1991–1994 when there were 164 spills, although none were major. Since 1995 the number of spills has been sharply reduced with total losses from 1997–2000 totalling only 6.89 barrels (1 m³).

The steel pipe is resistant to gunshots, but on October 4, 2001, a drunken hunter shot a hole into a weld, causing a spill of about 6,000 barrels (950 m³). The hunter was later arrested.

The worst spill relating to the pipeline was in 1989 when over 260,000 barrels (41,000 m³) were lost by the Exxon Valdez.

See also: Trans-Afghanistan Pipeline (TAP)

External link

• Pipeline facts