We started with an 88-acre, hilly jobsite covered with granite outcroppings among thick stands of pine and juniper and we’ll finish with a 130,000 sq. foot building pad for a Home Depot store surrounded with a paved parking lot,” said Tim Hulbert, owner of Hulbert Finish Grading, Phoenix, Ariz. “The project requires a lot of earthmoving. We’ve got 20-foot gullies on one side and 18-foot fills on the other, which means we’ll easily move close to a half-million cubic yards of soil.”
Hulbert is describing a Payson, Arizona project that has been plagued by almost eight inches of rain in a two-week period followed up by a foot of snow a week later. Add to that the black cloud of a $16,000 per day liquidated damage fee if they miss the completion deadline and you’ve got a Webster’s dictionary definition of stress.
Hulbert, however, has been able to keep the stress at bay and remain on schedule. “We’ve been using Trimble’s new GCS600 Grade Control System on our new Komatsu Laterra GD655-3 motor grader,” Hulbert said. “It’s not only the muscle that the 33,000 pound motor grader provides, but the precision and capabilities of the Trimble grade control system, that have kept us on schedule.”
Precision on an Un-precise Site
“We needed to be ± a quarter-inch after dragging the subgrade on the building pad,” Hulbert stated. “With this rocky ground, that’s not easy to do. With the new Trimble® GCS600 system we were right on target. The surveyors came in and took measurements on a 10- to 15-foot grid and we averaged out within two-hundredths on the whole pad. Then, we put the aggregate base on the pad and finished it off, and the system did an excellent job – the pad wasn’t off tolerances at all.”
"We needed to be ± a quarter-inch after dragging the subgrade on the building pad. With this rocky ground, that’s not easy to do. With the new GCS600 system we were right on target."
Tim Hulbert, owner of Hulbert Finish Grading, Phoenix, Ariz.
The Payson Home Depot project requires steeper than usual cross slopes to maintain the height for the building and parking lots – plus the snugness of the property line to the improvements. “We like the new GCS600 system a lot because it goes up to 100% on the cross slope,” Hulbert said. “Most of our slopes here are 3:1, which is very steep. Our old system was limited to 19.9% maximum cross slope, which isn’t even a 4:1 cross slope. Without the GCS600, we’d been killed as far as the time needed to pull tape and set grades on the severe slope.”
The parking lots themselves provide some challenges. There are grade breaks throughout the parking lot for water control. “So with the GCS600, I’m able to look at the plans and take my elevation difference from the grade break down to the catch basins and figure the percentage of fall which I dial into the cross-slope side and use that percentage to carry my grade. With the Trimble system it’s easy. If it’s not done right, there’s the risk of water puddling up on the asphalt, which would be bad news.”
Especially with this rugged, rocky terrain, Hulbert is appreciating the new heavy-duty masts and their hardier mountings. “With all the rock we’re ripping through, the stronger mounts on both the masts and the receivers have been critical. Additionally, I like it that the sensors are better protected from the shock of hitting rocks – our cross-slope side doesn’t lose the grade. Because this new system performs under tough conditions so well, I can actually go faster and maintain a smooth grade.“
Powerful, Accurate Technology
“The whole GCS600 system is also definitely more powerful and sophisticated,” Hulbert said. “The new receiver is much more accurate and communicates with the mast at a higher level – things like being able to do a search for the transmitter are nice, since it holds the elevations, so you don’t need to set up should a connection be lost.”
Hulbert Finish Grading has been using the GCS600 Grade Control System for several months. “It’s been keeping us on schedule, despite all the wet weather and challenging terrain. After using this system and seeing first hand all of the advantages, I can’t see using any other system.”
Published in Trimble Productivity, Spring 2005 (Customer Profile)