Iron Keeps U.S./Mexico Border Fence From Sinking in the Sand

Tue August 25, 2009 - Southeast Edition
CEG

The border fence is designed to stop vehicles while allowing wildlife passage.
The border fence is designed to stop vehicles while allowing wildlife passage.



Working to a tight deadline, two Wirtgen WR 2000 XL soil stabilizers consolidated the foundation, and alongside access road, of the fence under construction along the United States/Mexico border.

“The Fence,” as it’s called, changes character from location to location, depending on regional needs. In some locations, burdened by excessive crossings of individuals and groups, it takes the form of an impassable pedestrian wall.

But along the remote New Mexico-Chihuahua border west of El Paso, Texas, the prime concern is stopping vehicular traffic carrying drugs or human cargo — while not impeding wildlife movement — so the structure is composed of open steel barricades connected by welded sleeves.

In the meantime, the area U.S. Border Patrol is able to interdict any individual or group movements that may try to cross the vehicular barricade after a minimum 20-mi. hike through the Chihuahuan desert.

The border already is demarcated by monuments erected along the line, and the fence and access road follow these while falling within United States territory.

Road, Fence In 32-ft. Corridor

The machines were working on a 46-mi. (74 km) section of the fence from west of Santa Teresa, N.M., west toward Columbus, N.M., and operating in a 32-ft.-wide (9.7 m) corridor.

The access road itself will consist of the existing sand/soil/clay mix, stabilized in situ 10 in. (25.4 cm) deep with water and compacted, then topped with a stone base course layer. Where the road and fence cross a dry arroyo, crushed stone layers with geotextile, topped with a mat made of linked precast concrete cells, will form a ford.

In order to place the prefab fence sections, the access road has to be stabilized, said Steve Donnelly, sales representative of Nueces Power Equipment, El Paso.

“If they place the fence in unstabilized sand, it will just sink in over time,” Donnelly said. “Instead they make one pass with the reclaimer, and get 92 percent density after compaction.”

Water was being injected using 1,800 Lpm pumping systems installed on the WR 2000 XL, and was supplied by tanker trucks. However, in some locations, where the sand was so loose tanker trucks could not be hooked up and pushed through, water supplied by sprinkler trucks was providing enough moisture to get compaction.

To smooth the way, motorgraders were being used both ahead of and behind the stabilizers, in conjunction with the compactors.

Leading Way With WR 2000 XLs

The WR 2000 XLs are just what’s needed for the high-profile stabilization project, the contractor said.

“The WR 2000 XLs are working very well for us,” said Bill Burgess, director of maintenance and equipment planning, James Hamilton Construction Co., Silver City, N.M. “I like the way they are set up by Wirtgen, and feel that they are a better product than the brand we have been using. They fit our needs better.”

Burgess lauded the serviceability of the WR 2000 XL.

“I like the way the systems are set up,” he said. “They are a lot more advanced. Compared to the product we have been using, our old brand is old-school technology, with the chain boxes and the drag clutches. But the Wirtgen is set up for higher productivity and serviceability. The operator has everything he or she needs to maintain his tips and to take care of things right there. They are more technologically advanced.”

Earlier, on a different job, Burgess did take the opportunity to see the performance of the WR 2000 XL side-by-side with Brand X.

“The WR 2000 XL did a lot better job in terms of production feet per minute,” Burgess said. “It also, with its four-leg support system, can do slopes that we could not do with the other machine … which we needed on that job.”

Burgess also took a moment to talk about his distributor.

“The support we’ve received from Nueces Power Equipment — from their demonstrations, to the training of operators, to maintenance — needs to be mentioned,” Burgess said. “They do everything they say they are going to do, and more. Their training is excellent from an operator and a maintenance standpoint. That’s worth a lot as far as an equipment store is concerned. You simply can’t ask more of a distributor than what NPE has done for us.”

For more information, visit www.dignpav.com.

This story was reprinted from Wirtgen Technology, Fall/Winter 2008.