Roberts retrofitted a couple of WWII-vintage military 6x6 trucks with his spreader. The system has worked so well it's now installed on all seven of the company's spreader trucks.

Third, Slurry had to adopt technology that allowed for high-speed, high-capacity, high-precision work. As it has for so many contractors, the technology solution came down to lasers and GPS. Slurry had frustrating results with systems from other manufacturers before finally settling on Topcon products provided by Atlantic Laser Supply. Among the Topcon pieces Slurry is using at Dulles are two PZL-1 lasers, a hiper + rover, and mmGPS units on two motor graders. The general contractor, Lane Construction, has a GPS reference station set up at their job trailer.

Adapting to the technology wasn't hard. Roberts says he had about a two-week learning curve where he worked with the equipment a little bit each day. "The most important thing for me was learning to trust the equipment," he said. John McCormick, their rep from Atlantic Laser, put on a demonstration that helped build the trust factor. "With all the data loaded into one of our graders, John laid a quarter on top of one of our hubs. Using the Topcon millimeter GPS the grader operator swept the quarter off the hub and never disturbed the hub itself."

Big, But Exact
Slurry's task at Dulles is to provide a stable base for the runway and associated taxiways. They're working some 639,000 square yards (132 acres), stabilizing it by mixing cement into the soil. The work is not only high-volume, it's also highly technical. There's little room for error in any task related to the airline industry.

The process begins with the removal of all native topsoil. Screened fill dirt - free of rock and organic material - is brought in. Slurry then applies Type I/II Portland cement at the prescribed rate. The cement is mixed with the soil and the mixture simultaneously pulverized with Wirtgen reclaimer machines. Slurry has two units - a 2500 and a 2500S - on site. To meet spec, 80 percent of the soil, absent of rock, must pass through a #4 screen sieve. Openings in a #4 screen are 4.75 mm, or about 3/16" square. It takes two to four dry passes to work the soil down to size.