A Better Way to Tame Alaskan Tundra

Pipeline Maintenance Digs
Prudhoe Bay, on the northern coast of Alaska, is the severely cold, desolate location of TransAlaska pipeline’s Pump Station #1. Winter temperatures at Prudhoe Bay dip as low as -56° F, with wind chills approaching -100° F. Frost depths reach more than 2000 feet in some areas. Alyeska Pipeline Services owns and operates the 48-inch diameter, 800-mile pipeline, which carries more than 1.5 million barrels of crude oil from Prudhoe Bay to Valdez daily. With prices near $50 per barrel, the pipeline currently delivers approximately $75 million worth of oil each day. With the pipeline generating this level of revenue, downtime is unacceptable.

To ensure safe and efficient maintenance of the pipeline, Alyeska contracts both Houston/NANA and Alaska Petroleum Contractors, Inc. (APC) to perform more than 200 maintenance digs a year for the northern half of the pipeline. One would assume that these digs would be performed in the summer, when weather conditions are more favorable for outdoor work – this is not the case. "Because we work on the tundra," said Kenny Broker, heavy equipment coordinator for Houston/NANA, " environmental officials are very strict about work permits. Basically all pipeline maintenance has to be done in the winter, when the tundra’s surface is frozen solid, so we don’t leave any footprints or tracks."

According to Bob Bumbaugh, assistant superintendent for APC, both air and steam heaters have been used to thaw the ground, but with limited success. "We’ve used air heaters up here, but it requires building an enclosure to direct the heat into the ground," Bumbaugh said. "[Using air heaters], it’s difficult to contain the heat with the high winds and extreme temperatures." Steam heaters have also left much to be desired. "The problem with steamers is that the ground up here is already very wet, and the steamers just pump a lot more moisture into the ground, leaving a big muddy mess," Broker said. "Worker safety is also a concern with steam heaters because there is a danger of getting burned." Thus, both Broker and Bumbaugh were anxious to find a safe, effective method of ground thawing to maintain the massive pipeline.

The ground thawing solution presented itself when a Wacker Neuson Climate Technology dealer contacted Kenny Broker proposing APC try a hydronic E3000 Ground Heaters unit for thawing along the pipeline. Broker answered, "If they work in these severe conditions, we would be very interested in renting or purchasing some."

The dealer confidently accepted Broker’s challenge to "tame the tundra." Loading up two model E3000 units, the dealer representatives traveled more than 400 miles to the frozen tundra of Prudhoe Bay.
"We chose a gas line dig at Pump Station #1 for the demo," Broker said. "Since the natural gas lines power the pump station turbines, we have to make sure the lines are intact and not corroding." The gas line was buried about 6 feet deep and the dig required thawing an 800-square foot excavation area. The ground temperature at the dig location measured -23° F.

Before the dig, excess snow was cleared from the 800-square foot area. Hydronic heater hoses were placed six inches apart over the entire area, and about two inches apart directly over the gas line. A polyethylene vapor barrier, along with three layers of R-6 rated insulation blankets, were placed over the hoses to direct the hydronic heat into the ground.

After 40 hours of run time, the E3000 had thawed to a depth of 40 inches. Within 115 hours, roughly 5 days, the required thawing depth of 6 feet was achieved. The E3000 effectively proved that it could thaw ground – even on the tundra. "We’ve continued to use the Ground Heater with great success," Bumbaugh said. "It’s a more effective way of directing heat into the ground. It drives the heat and moisture way down, thawing faster than other methods." Additionally, the E3000 from Wacker Neuson offer s a safer method of thawing. "With the way the Ground Heaters work, there’s no danger of being burned as with steam heaters," Bumbaugh said. "And it’s environmentally safe!"

Bumbaugh also found the simplicity of the Ground Heater attractive. "I use fewer man-hours in the field because it’s so easy to set up – two or three guys can set it up in less than an hour, and it doesn’t have to be constantly monitored," Bumbaugh said. "After setup, we just let its heat soak in for a week or two, and then come out to do our digs. With a steamer, we would need a whole crew out there, all day and night." The Ground Heater not only saves on manpower and expenses, but also keeps personnel out of these dangerous weather conditions. "Anything that can reduce our time spent in the field under these arctic conditions is a big help," Bumbaugh said.