GPS Technology Delivers Design Grade in One Pass Through Rainy Weather

The challenge:

Cut grades fast between consistent weather delays to develop a 12-acre store site without blowing the construction schedule

The players:

Envision Contractors LLC
Construction Engineering Solutions

The process:

Envision Contractors LLC completed the site prep for the new Owensboro, Ky., Rural King Farm and Home Supply store despite persistent rain on silty-clay soil. The 100,000-square-foot store will be twice as large as the old one and is located on 12 acres next to U.S. Route 60, which beltlines the city.

“When we started the project we were confidently planning on completing it in 45 to 60 days,” said Kevin Grant, project manager with Envision Contractors. “With the persistent rain we’ve had for the past month, our schedule is growing closer to 90 days.

“With the rain, we really have had to hustle on the clear days,” said Grant. “There is no margin for error, which means we need to accurately achieve grade in one pass with our three dozers and a motor grader.

“We won the Rural King contract not only because of our price but because we have a technology advantage with the Topcon systems that others don’t,” Grant adds. “Even with rainy weather delays, we’re getting the job done quicker than others could and achieving the quality results they expect.”

The grading machines Grant’s crew of four uses are all equipped with Topcon GPS/GNSS grade control systems.

“We wouldn’t be anywhere as efficient and accurate without Topcon technology,” Grant said.

The Rural King site was formerly soybean and corn farmland. Beneath the top approximately foot and a half of farm soil is moisture-retaining silty clay, typical for the region. Envision added cement stabilizer while grading the store’s building pad, to ensure stability for the structure.

The site had a hill, which was leveled. The hill provided about 30,000 cubic yards of borrow used throughout the site. No additional soil was required.

In addition to the building pad, Envision constructed 247,000 square feet of parking and landscaping surrounding the building and a 600-foot road extension leading to the facility.

Grant worked with Glenn Etienne of Construction Engineering Solutions, Leopold, Ind., to create the digital model of the roadway extension, in conjunction with Envision Contractors’ own modeling software. The digital model facilitated the use of machine control.

In total, the company moved 85,000 cubic yards of soil. They used two Caterpillar D6N LGP track-type tractors and a Cat D5N LGP track-type tractor. All three dozers were equipped with Topcon 3D-Millimeter GPS+ machine control that combines laser and GPS capabilities. A Cat 120H motor grader equipped with a Topcon 3D GPS+ auto control system was also used on the project.

Envision also used two handheld Topcon GRS-1 GNSS receiver and field controllers, and three Topcon Tesla RTK GNSS rovers as construction grade checkers.

“I really like the Tesla RTK’s large touch screen display and easy-to-use software,” said Grant. “It’s super fast at performing complex field calculations.”

On the Rural King farm and home supply store project, Envision has four employees dedicated to completing the site development and relied on product support from its local Topcon dealer, Earl Dudley, of Nashville, Tenn.

“The efficiency of the Topcon equipped machines is key to our ability to running productively and achieving exacting results in one pass,” Grant said. “With this project - as with all of our projects today - there is no time for errors. Rework is too costly. It would take probably 30 percent longer without the technology.”

And, then, the weather created unwanted delays.

“When we started the site development project, we expected to be completing the project much sooner than we are with all the rain delays we’ve been experiencing,” Grant said. “Any clear days we have, we need to maximize our productivity. Clearly, here’s where the machine control systems really helps. The operators can hop into their dozers and have the plan right there on their screens and know exactly what needs to be done.”

Jeff Winke is a business and construction writer based in Milwaukee, Wis. He can be reached through www.jeffwinke.com.

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