The pipeline’s 796-mile route south from Prudhoe Bay was set to cross three mountain ranges, 20 major rivers and 300 streams before reaching the ice-free port of Valdez. The highest point, at 4,800 ft, was Dietrich Pass in the Brooks Range. As the first-ever oil pipeline in the Arctic it posed serious design challenges. Seismic and ground conditions were not ideal. Some 420 miles of the route was over permafrost. The pipeline could not be buried in those areas as the heat of the oil would melt the permafrost, turning it into a slushy mass with no bearing capacity. 

The aboveground line rests on 36,000 steel bents and runs in a zigzag pattern, allowing up to 20 ft of horizontal and 3 ft of vertical pipe movement to endure earthquakes. At every 700 ft to 1,800 ft, the pipe is clamped firmly to anchor assemblies to prevent horizontal movement. Between the anchors, the line is mounted in sliding shoe assemblies.

Contractors Join Megaproject

Alyeska chose Bechtel as construction manager for the pipeline and haul road, with 500 employees based in Fairbanks. Fluor was CM for the 12 pumping stations and a tanker terminal at Valdez, with five contractors each awarded segments of the pipeline that was designed by Michael Baker International. 

Early on, Alyeska admitted to startup delays, some due to a lag in delivery of drill rigs and drill bits, as well as a slow start on the Valdez oil tanks. A shortage of mechanics and welders and a high turnover among laborers presented further difficulties. A 1975 ENR article stated: “Many contractors continue to blame construction problems on the relationship between Alyeska and Bechtel.” Alyeska ended Bechtel’s role as CM, and issued a new contract that designated the firm as “construction/technical services manager.”

The line's 84,000 bent piles had to be driven from 22 ft to 50 ft below the permafrost thaw area to provide adequate bearing. Despite thousands of test borings and soil samples, geotechnical surprises meant drilling gear was often mismatched to soil conditions, causing expensive delays. Since the 48-in.-dia pipe was mounted only 2 ft above grade, it posed a barrier to local wildlife. There are 554 locations with higher clearances to serve as animal crossings.

Initial construction in 1974 saw completion of a two-lane gravel haul road running 350 miles from the Yukon River to the North Slope. The 28-ft-wide road embankment was 5 ft thick to protect permafrost. Crews also built gravel work pads for the 5,000 pieces of equipment and 29 work camps, each with a 5,000-ft gravel airstrip. By December 1974, there were 3,000 workers engaged in drilling holes for piles, finishing concrete footings for the Yukon River Bridge and blasting rock at Valdez to gouge an oil tank platform out of a mountain.

Hiring ramped up in the spring of 1975 and the workforce peaked at 21,600 in September, dropping by more than half the following winter, with the cycle repeating in 1976.

Tough Terrain

As a condition for obtaining a permit to build a pipeline that traversed federal land for over two-thirds of its route, Alyeska agreed to an extensive federal and state surveillance effort to ensure environmental safeguards were met. The Interior Dept. and state monitoring teams totaled 95 staffers who had the right to stop work if necessary, and did so several times.

One of the first sections of pipe placed was one of 1,900-ft across the Tonsina River and its adjacent flood plain. Thirteen sideboom tractors brought the vinyl-wrapped pipe to a 40-ft-wide gravel work pad and placed it in a water-filled trench up to 17 ft deep. The 300 ft of pipe under the active river channel had a 9-in.-thick protective concrete coating. Nine-ton concrete saddle weights pinned the pipe in position to counteract buoyancy until the line was filled with oil.

The most difficult pipelaying was at Thompson Pass in the Chugach Mountains, which had a slope of 47°—steepest on the route. Contractor Morrison-Knudsen had to use a kiloton of explosives to cut a 3,700-ft-long trench up the slope. A winch-driven cableway system carried spoil down and pipe sections and equipment up. Customized 92-ton tracked vehicles were used to pump fine-grained backfill material through 10-in.-dia hoses.

An orthotropic steel box girder bridge across the Yukon River was completed four months behind schedule in October 1975. The 2,280-ft-long structure enabled heavy truck traffic to access the northern stretch of the project. It also carried the pipe on an external, cantilevered steel framework. The pipeline crossed the Tanana River on a pipeline-only bridge with two 170-ft-high towers 1,200 ft apart— Alaska’s longest suspension span.

The terminal in Valdez cost $1 billion to build and featured four tanker berths and 18 oil storage tanks. Workers excavated 14 million cu yd of overburden to reach bedrock. Each tank rested on an asphalt-sand-gravel cushion inside a concrete ring wall base. Welders assembled the 62-ft-high, 250-ft-dia steel structures, each holding 510,000 barrels.

Work Challenges Met

Workers were trained in Arctic survival by two former U.S. Army sergeant majors with Arctic experience. “Warm water or urine can free bare hands that have quickly frozen to tools or other metal … shelters can be dug in snow if workers are trapped outdoors … anyone who leaves camp must travel with at least one other person,” a 1975 ENR article noted. Those traveling by vehicle had to carry a sleeping bag in case of being stranded. Recognizing that long working hours, cold winters and limited recreation could foster alcoholism in the workforce, a union-contractor initiative encouraged supervisors to intervene and steer candidates into 12-step recovery programs rather than fire them.

Union strife kicked up in 1975, despite a no-strike provision in the contract. A brief walkout of 4,200 workers over Teamsters’ union grievances was ended by a court injunction. Later, almost half of the project's 2,000 welders walked off the job for two days after they were denied the two-week rest and relaxation period guaranteed by their contract.

Alyeska installed Frank P. Moolin Jr. as project construction manager in June 1975, following Bechtel’s demotion. He decentralized authority, giving field managers responsibility for making more decisions but demanded detailed productivity reports. When work stopped for any reason, Moolin decreed that crews had to be sent back to camp where they would not be paid. He also started a sweepstakes competition among the five contractors, charting their progress against their goals—steps that helped put the project back on track.

Quality control problems plagued the project from mid-1975 to its completion. When Alyeska discovered that 8% of the manual welds in a 150-mile section of pipe had defects or deficiencies, with numerous weld X-rays falsified, it rechecked each of the 3,748 welds in that section, including about two thirds that were buried, and fired its X-ray services contractor. 

The U.S. Interior Dept. and the U.S. Dept. of Transportation Pipeline Safety Board ordered an independent investigation of the weld X-rays and repair records for 30,800 welds done in 1975. A whistleblower employee of the X-ray contractor testified before Congress that he was pressured to falsify results. President Gerald Ford sent a federal fact-finding team to Alaska in 1976 to probe the situation. By October 1976, Alyeska had repaired all 263 substandard welds and X-rayed them again, at a cost of roughly $2,000 per weld.

Thirty two workers died during pipeline construction but as the largest peacetime project in U.S. history, the Trans-Alaska Pipeline had an outsized impact on Alaska. Fairbanks’ population doubled in size in the first year to 60,000 from 30,000. 

Shortly after the last weld was made in June 1977, 27 months after the first weld, oil began flowing southward from Prudhoe Bay at about 1 mph, reaching Valdez one month later. Oil entered the pipe at 140° F, and with friction offsetting cooling, maintains its temperature even in winter.

The final project cost was $10 billion, heavily impacted by high inflation and about a  $1 billion overrun. The project met its deadline, however, and ENR cited Moolin for recognition, selecting him to receive in 1977 what now is the Award of Excellence..