Alaska Construction & Oil; February 1979
Always looking for a better way to do things, Erwin Long invented a self-refrigerating pile system (now used widely in Alaska), and then modified it for a variety of applications. Last year Long began fabricating and assembling the units in Anchorage instead of contracting all the work to Outside firms.
Now he is developing compact, portable machines for drilling, installing and charging the units in remote areas where conventional machines are not available. He also is setting up a new company in Canada to fabricate and sell the piling systems in that country.
Long and co-owner, Sam Parsons, formed Arctic Foundations, Inc., in 1973 to manufacture and sell Long's invention, the Long Thermo-Pile. At that time Long was chief of the foundations and materials branch of the Alaska District, U.S. Army Corps of Engineers For the first three years, until he retired from the corps in July 1976, Long served as engineer and consultant on his own time while Bob Velikanje served as full-time manager of the company's day-to-day business. Velikanje, who is still on call as an Arctic Foundations consultant, specializes in estimating field costs which, according to Long, are often the biggest expense in an Alaska project.
The self-contained Long Thermo-Pile uses a two-phase heat transfer system to conduct heat out of the ground. By the simple process of convection through vaporization and condensation, heat is taken out of the ground and dissipated through fins into the air. Conversely in the summer, the gas inside the units limits the warm air's heat from flowing into the ground, thus maintaining a permanently frozen soil condition near the pile.
Although early units were charged with propane, ammonia or Freon, all units, except those made of copper, are now charged with carbon-dioxide unless otherwise specified. Sometimes Thermo-Probes are made from copper so they can be bent to fit in a small plane for transport to a remote site. Freon F-12 refrigerant, which has a lower pressure, is used to charge the copper units.
The Long Thermo-Pile and Thermo-Probe systems are particularly effective in areas of marginal permafrost where the ground is not frozen solidly or where it tends to thaw during warmer summer months and freeze again in the winter.
Long said he first had the idea while seeking a solution to a Corps of Engineers problem in Bethel. He said that when he suggested it, the typical reaction was: "Yes, that sounds intriguing but it sounds too simple – someone must have already tried it."
The Long Thermo
He contacted several research institutions and discovered that the principle had not been used in that application. Becoming impatient with the long-range programs the institutions outlined for testing the units, Long decided to develop the idea on his own. He began experimenting in his backyard and by 1960, when he applied for his first patent on the thermo-transfer process, he had several installations at his home.
Long owns patents to the Long Thermo-Pile in the United States and Canada. While he worked for the Corps of Engineers, he granted them royalty-free use of the device, but now the U.S. patents have been assigned exclusively to Arctic Foundations.
The first commercial units were installed by the corps in 1960 at Aurora and Glennallen communication sites. The corps ordinarily does not like to use experimental methods; but when it discovered that conventional pile foundations would not work at Aurora because there was a thawed aquifer 13 ft. below the ground surface, it agreed to try the Thermo-Pile. Long said his device was so cheap to install that if it did not work, it could easily be converted to a conventional refrigerated system. The constructed foundations would need no alterations and the project would still be cost effective, Long argued. As it turned out, all the foundations proved satisfactory except one tower footing which was located near a buried uninsulated steam manhole. That Thermo-Pile was modified to a Freon refrigeration cycle.
Some of the more recent installations of Long's system include those installed last October at the Alaska National Guard's Bethel maintenance shop; power line structures for Golden Valley Electric and Rogers Electric in Fairbanks; private Fairbank's residences and the state's below-grade heated storage vehicle building in Galena.
Most contractors install the units themselves but Arctic Foundations will do the installation when the contractor requests it or when installation equipment is not available. The company recently installed probes adjacent to a school in Tetlin and a house in Fairbanks.
Other recent jobs include tower foundations in Fairbanks for CollinsRockwell, a contractor from Dallas; pilings and probes for a large shopping center and a three-story apartment building in Kotzebue for Gittins Construction; school buildings in Glennallen and Northway; University of Alaska buildings in Nome and Bethel; a National Bank of Alaska building in Glennallen,, nine apartment buildings in Fairbanks; a school addition in Nulato; copper probes at Shagaluk which were flown in on a small plane, and generator buildings at Noorvik for the Alaska Village Electric Association.
At the time of Long's invention, driven H or straight pile was standard. However, in particularly rocky areas, it was difficult to auger or drive pile. Long's solution was to put rings on his piles which created shear stress in the soil making it possible to install thinner and shorter piles. His ring piles also had better load distribution which meant that fewer piles were required to handle the load.
Conventional refrigeration systems develop strength by adfreeze, an adhesion between frozen soil and the pile surface. The ring pile gets its strength from the flat horizontal rings around the pile . These provide perpendicular resistance to the vertical force from the load stress of the building placed on the piling. Ring piles have two to three times the resistance to failure than adfreeze piles, Long said.
Early ring piles had rigid rings while later designs us e a thin blade designed to flex with pile compression permitting transfer of stresses down the pile preventing premature failure of the upper surfaces . The thin blades also have a lower heat conductivity on hot days.
The thin blades can be placed in a helix configuration to eliminate slurry backfill around the pile . A pile with helix blades and a drill head on the tip can be screwed into the walls of a hole augered to pipe diameter.
Ring piles can be ordered with or without refrigeration, with flat rings or helix rings, and with a drill bit or an end bearing tip.
Long developed modular piles which can be fastened together to increase load strength. One of Arctic Foundations’ more unusual jobs was the tower foundation for Alyeska Pipeline Service Co. A communication tower installed at Gakona for the trans-Alaska pipeline project required that each foundation have a load bearing capacity of 350,000 lb. Six individual piles were placed together in a modular configuration to meet the unusually high load requirement.
Long has also devised a way to use smaller diameter piles and angle (or batter) piling to carry horizontal wind and earthquake loads.
Another application of the basic idea is the Thermo-Probe, developed for on-grade structures . Thermo-Probes can be used in vertical or horizontal installations in such buildings as warehouses and heavy equipment garages where the unit floor loading is very high. Thick in sulation must be placed on the floor and the self-refrigerated probes are installed in the fill under the structure.
One of the first projects for the corps was river diversion at Galena where Thermo-Probes were used to maintain the permafrost.
Current probe designs in corporate sloping units of small diameter pipes from 3/4-in. to three in. and horizontal units made from four-in. and six-in. diameter pipes. The horizontal tubes are half filled with the charging fluid. Another method is a series of vertical units under the structure. Pairs of 1/4-in. lines are used to connect the evaporator unit to the condenser unit.
Probes with fins are more expensive because of the welding costs but are required in some applications. Because of their outside use , the fins must be electrical-resistance welded to prevent corrosion. Therefore, a specialized plant in the Midwest still manufactures the fin design. The larger piles still are produced in Seattle because of regulations requiring pipe over 6 in. to be welded in a code-shop. Long hopes to receive a code-shop rating someday so all fabrication, including finning, can eventually be done in Alaska. At the present time, however, large diameter pipe is not stocked in Alaska, making local manufacture of larger diameter units less feasible.
Long added fabrication capability to Arctic Foundations in January 1978 when the company moved into larger facilities at the Raspberry Industrial Park, 6613 Arctic Blvd., Anchorage. The staff is small, consisting of Long and one full-time welder with additional help hired as needed on a part-time basis. The full-time certified welder is Jim Tweto, who also has experience at welding type inspection work. Therefore, he can do the welding and make inspections, too. Long personally inspects each stage of work done with a Lincoln wire-feed welder.
The personal inspection assures a much higher quality product, Long said, a major advantage of having fabrication and assembly done in Anchorage. With inhouse work, careful inspection can be given to such things as threaded valve connections which often don't get such close attention in contracted work, he said. Because of the improved quality, the early jobs produced in Alaska proved it actually was cheaper to fabricate here than Outside, Long said.
Another advantage of local manufacture is faster delivery time, Long said. He keeps a large number of the circular units and prefabricated parts in stock. Normally an order can be assembled in Alaska in five to 14 days , depending on order size, he explained adding, by having more direct control over the work, he can provide more help to contractors in meeting their schedules .
Analytical in his business philosophy as well as his engineering, Long believes that scheduling purchases is a key to success in Alaska business. He said many Outside suppliers don't realize that a delay in a shipment can cause a year's delay in a project because of the short construction season.
Long has devised ways to manufacture his units with as little manpower and space requirements as possible, noting that in Alaska space rental and labor costs can run a company out of business if not tightly controlled.
In order to provide more efficient and economical installation services, Long recently bought a Tomeo trailer to carry liquid carbon dioxide to jobs in the field. He said the compact trailer carries 1,000 lb . of the liquid gas which provides the equivalent of twenty-five 50-lb. gas cylinders. Long ordered slight modifications to the safety valves to permit air transport of the trailer unit. A five-hp carbon dioxide pump is used with the trailer to charge units in the field.
Another recent addition is a New Holland skid steer loader with a special drill mounted on it. On this unit, too, Long designed modifications so it could be shipped in the skyvan-type aircraft used on the smaller airstrips at remote Alaska
Since regular drills won't fit in aircraft, he designed standard sizes on his refrigeration units so the units could be run through the drill assembly, eliminating the long fixed kelley bar assembly of a normal drilling machine. Now the units have standard outside diameters of 3-1/2 in. and six in . The 3-1/2 in. o.d's go through the drill assembly while the six-in. o.d. fin units also have a 3-1/2 o.d. pipe.
Probes and small diameter piles are prefabricated in lengths of 55 ft. which will fit in a Hercules airplane. Units longer than 55 ft. are welded, charged and tested in the field.
The drill unit also was modified to drill at an angle as well as vertically since probes and piles often are installed at an angle under existing or on-grade structures.
Long hopes his modified drill will make installation of his Thermo-Pile systems more economical for the private homeowner. He believes his system is cheaper than wood piling and points out that timber foundations
must be much longer than his system to prevent frost heave.
This year, Long is planning to set up a test pile in either Anchorage or at the Cold Regions Research Laboratory at Fairbanks. Many tests have been made on his piles but controlled test results have not been compiled. Since the tests require continous monitoring he is hoping to find a suitable site in Anchorage so he can monitor the results himself and cut costs. (Long is an internationally recognized soils engineer who has presented papers at several Permafrost International Conferences sponsored by the National Academy of Sciences and the National Research Council.)
Long plans to purchase the latest electronic monitoring equipment. Again, using the analytical approach, he has devised a way to combine a number of tests into one program to get the maximum data for the least possible cost. He is having a jacking and control system built to his specifications. Some of the testing could take months but will provide data which can be put on a log scale and extended to 100 years, the normal timeframe used in designing, he said.
Another current project of Long's is organization of a new company which will fabricate his units in Canada. Although the company will be largely Canadian-owned so it will qualify for Canadian contracts, his Alaska company will furnish assistance in setting up the sales and fabrication operations, Long said. He expects the new company to become operational this year.
With Erv Long directing it, new endeavors and better ideas will undoubtedly continue to be developed at Arctic Foundations.
By Pat Richardson