T.H.E. Machine Company, Glenwood, Minn., builds five models of trailer-mounted Thawzall ground frost removal systems.

The Units use oil or gas vapor-fired boilers to heat glycol, which is circulated through up to 5,000 feet of hose. The system has proven to be a fast and efficient method of ground-frost prevention.

Thawzall equipment was introduced to the construction market in the autumn of 1996, designed to thaw frozen ground in winter conditions.

"After getting the equipment out to the marketplace, we found other uses for it," said Chuck Porter of T.H.E. Machine Company.

"For example, last winter in New York, a train derailed. The tanker cars had chemicals and food products in the liquid state. That had to be evacuated from the tanker cars.

"Unfortunately, the contents were cold, and workers were not able to evacuate the liquids."

From there it was Thawzall to the rescue.

"Thawzall equipment was brought to the derailment site, and it was determined that workers would wrap the tanker cars with Thawzall hoses, cover them with construction blankets to heat the fluids, and then evacuate.

"Thawzall performed the task with high marks."

Porter recalled that, two summers ago, the Olympic hockey rink in Colorado Springs, Colo., was in need of serious repair.

"However, it was determined," Porter said, "that under the rink area there was 18 feet of frost. Thawzall to the rescue again."

This project took several weeks to complete. The top 9 feet of frost was

thawed first to allow for initial excavation. Following this, the next 9 feet of ground was thawed.

"Thus 18 feet of frost vanished," said Porter.

Another Colorado project involved a semi-truck accident.

"The truck was carrying petroleum products," Porter remembered.

"The driver lost control, the truck went down an embankment and it crashed through a frozen lake. This was a potential environmental nightmare."

Thawzall was to provide the answer to cleaning up the petroleum at the crash site.

"Thawzall hoses," Porter explained, "contain environmentally safe fluids. The hoses were heated to 180 degrees and laid out in a grid configuration."

The hoses melted through the ice, resulting in a number of ice chunks, which were removed.

"Then the cleanup crew pumped the contamination out of the lake."

Thawzall has also been used to thaw ice dams on flat roofs as well as to warm concrete to prepare for epoxy coating of concrete floors.

"The biggest area of growth," Porter reported, "is for curing concrete.

"This procedure is done by thawing the ground, getting the temperature up to 70 degrees, then removing the hoses and pouring the concrete onto a warm, preheated area. This ensures the start of proper curing.

"After troweling, we use our cold weather construction management station to reduce the fluid temperature over the slab to 80 degrees. Next we lay the hoses on top of the concrete cover with blankets. This results in the proper cure.

"Thawzall is available in five different models, allowing concrete curing application sizes from 5,000 square feet to 30,000 square feet in one layout."

Porter recalled that on an I-25 bridge in Colorado, 14 Thawzall units were required.

"The engineers specified that before any concrete was to be poured the rebar in the bridge deck had to be preheated to 50 degrees.

"Again, Thawzall performed perfectly."

T.H.E. Machine Company produces a variety of accessories to increase the versatility of Thawzall. The cold weather construction management system allows multiple tasks at the same time. A remote manifold can be used to lay hoses in differing zones away from the base machine. Forklift pocketed hose reel assemblies are available to provide 2,500 feet of additional hose.

All of the units can be hauled by a 3/4-ton pickup truck.

Being completely enclosed with no open flame, the units are extremely safe. For example, one recent Twin Cities metropolitan area project required thawing of a frozen water leaching system at a dump site. Because of methane gas, an open flame was not tolerated. Thawzall came to the rescue again, and the project was completed without incident in five days.




Above: Thawzall hose can be laid out in loops approximately 24 inches on center. Inset: Thawzall Model 5A can thaw up to 5,000 square feet of frozen ground per set up.

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