Trimble grade control hits grade consistently within three-tenths of an inch of the finished contour on the rocky slopes of Hawaii

The "Big Island" of Hawaii is located in one of the most remote spots on Earth. Almost smack dab in the center of the Pacific Ocean, Hawaii is a long stretch from San Francisco - 2,368 miles to be exact. Its out-of-the-way location and idyllic climate has contributed to its reputation as paradise. On the west end of paradise's Big Island, a large luxury housing development with a championship golf course is being constructed near Kailua-Kona .

The Shores of Kohanaiki project is being built on a 450-acre site, mindful of the delicate ecosystem, shoreline offset requirements, and indigenous culture. The plans include a 500-home, golf-course community featuring a shoreline park with public parking for more than 120 cars and an 8,000-sq.-ft. beach facility with a snack bar, restrooms and showers.

Groundbreaking for the massive project occurred during September 2005. It's anticipated the Shores of Kohanaiki will be completed in 2007. The complicated site prep is the responsibility of CTS Earthmoving, Holualoa, Hawaii.

“The west side of the Island of Hawaii is rocky with dusty, dry soil conditions,” said Scot Oshiro, Project Engineer with CTS Earthmoving. “But our biggest challenge is that the site is basically one big gradual slope – probably no more than two percent.”

Man, machine, technology

Established in 1983, CTS Earthmoving has between 15 to 20 of its 80-some employees dedicated to the site. “We have six CatTrack-type Tractors – three D 11Rs, a D10R, a D9R and a D8R – all equipped with the GPS-based Trimble^® GCS900 3D Grade Control System for automatic control” Oshiro said. The large machines are necessary because of the rocky, rugged environment.

“Without automatic grade control, it would have been a nightmare to maintain accuracy on the slope,“ Oshiro stated. “Because the dozers have the site plan right in the cab, we save a tremendous amount of time and increase our productivity. The operators hop in their machines in the morning and their orders to work specific areas are displayed. They can start in immediately – there’s no need to wait for surveyors to shoot grades, pound stakes and everything. All the information is right there – no interpolation by the operators between points that are placed 50 feet apart.”

Oshiro added: “The GCS900 Grade Control System is like having bulldozer operators and site surveyors all in one. It’s like having the surveyors sitting on the dozers telling the operators exactly where to grade.”

CTS Earthmoving first added GPS machine control on a Cat D11R in March 2005. A Cat D9R and a D4G were equipped with systems shortly thereafter. “At the time, we had been reading articles in the trade press about GPS being used on dozers for automatic grade control,” Oshiro said. “My boss came to me and said ‘we need this!’”

Oshiro said the operators were all for learning the GPS grade control system when it was first acquired. “Although, “ he said, “I have an experienced operator in his mid- to late-70’s who initially said ‘I’m old school and want to see stakes. I don’t believe this is going to work.’ We had to sit him down and show him how it works … how to change the screens … where his blade is positioned. And now, he loves it and keeps saying ‘This system is amazing, it’s incredible.’

“The fact that operators have instantaneous cut-and-fill feedback is something they like. When they are ripping, they can drop their blades and the display will say you need to drop the blade another two feet to be on plan. There is no down time waiting for a surveyor to come out and pound in a stake.”

One pass, no rework

A significant advantage of the GPS-based automatic grade control system, according to Oshiro, is that the work can be accomplished in one pass with little need for rework. “When this huge, complicated project is complete,” he said. “I will be able to say that the finished grades match exactly what is on the plan with no deviations or exceptions – including, the golf course design, which understandably has to be dead on.”

Of course, at the end of the day, and at the end of the project, CTS Earthmoving needs to make sure the Shores of Kohanaiki developer is happy. “The feedback we’re receiving from the developer is that we’re hitting grade consistently within three-tenths of an inch of the finished contour. They are amazed that we’re grading that close to the plan specs … and we plan to keep them amazed.”