Weather was the only delay while completing about 1500 feet of rock coring through granite/quartzite with the 3126GT.
The design of the 3100GT truck mounted rig and 3126GT track mounted rig are rooted in safe geotechnical drilling and the innovative rigs are already making their mark on the geotechnical industry. From mineral exploration to road assessments, companies identify the multitude of ways the geotechnical drill rigs benefit their business.
Power and Simplicity to Reach Greater Rock Coring Depths
Not even five years ago, CATAWBA VALLEY ENGINEERING AND TESTING — a full-service geotechnical engineering, environmental engineering, and materials testing firm in North Carolina — bought their first 7822DT to bring all exploration in-house doing hollow stem auger and SPT drilling. As they’ve grown to 20 employees the past few years, they added another 7822DT to do work for other companies. So when they had the opportunity to do higher-level rock coring in Virginia they looked to Geoprobe® for the solution.
“We were in Salina getting training on our Geoprobe® seismic CPT and saw the 3126GT. Once we secured the Virginia job, we thought it was a good opportunity to integrate the machine into our fleet of rigs,” David M. LeGrand Jr., P.E., owner, said.
On the exploration job looking for competent bedrock for mineral/aggregate purposes, LeGrand completed seven holes. In total they completed about 1500 feet of rock coring through granite/quartzite. Already LeGrand can see the advantages of the 3126GT.
“We have a 2020 7822DT set up to core confirmation rock core, but the difference between it and the 3126GT is remarkable. We wouldn’t be as deep as we are if we were running the 7822DT, it just doesn’t have quite as much juice,” LeGrand said. “We’re coring rock from 10-feet all the way down to 200-250 feet. The coring interface shows RPMs, temperatures, and bit weight in hole versus doing it all by feel, providing visual indicators to show we’re doing as much with the machine as we can without forcing things downhole”
The centerline head side shift and outriggers have also aided their efficiency.
“We stayed on our goal of at least a foot every five minutes. Shifting back and forth between different downhole tools, especially not swinging the auto drop hammer over, has been a huge time saver,” LeGrand said. “Our productivity has increased with the larger machine, larger winch, and ability to pull more rod directly out of the ground with the taller mast."
Troublefree Transitions and Versatility
As the oldest materials testing lab in New York, nearly 70 percent of MUNICIPAL TESTING LABS’ employees are engineers. However, during the past 10 years they’ve seen a ramp up of geotechnical work. Three years ago they talked Steve Wolf out of retiring to lead their boring department, growing to six full-time crews.
“We’re now doing waterfront jobs, 200 to 220-foot borings consistently, and barge jobs,” John Hicks, vice president, said. “We’ve really been doing what big-time boring companies do and just as well.”
Using their 7822DT for much of their expanding workload, when they heard about the NEW 3126GT workhorse they seized the opportunity to amplify their production. Municipal completes work in the five boroughs and tri-state area. From tight urban blocks to mountain tops, the crew appreciates the maneuverability of the 3100 series rigs.
“I was operating an auger rig, now I’m operating the 3100GT and I find the difference to be incredible,” Dave Johnson, driller, said. “The ability of the 3100GT to move from site-to-site without a transport truck is exceptional.”
While he admits the ergonomics and centerline head side shift took some getting used to, he appreciates the well thought out head and controls.
“The interchangeable operations from drilling to sampling is smooth and efficient with all operations on the same centerline. The head design helps with straight drill hole operations. Less time adjusting the alignment means more time drilling,” Johnson said. “Everything just lines up on the centerline. No swinging hammer over, it is much safer.”
With similar controls from 7822DT to 3100GT to 3126GT, he finds the transition from one machine to another easy while adding versatility and power.
“The 3100 series rigs have more diversity and ability than a conventional rig. The variable speed adjustments don’t result in any power loss. The hands-free, automation to control rotation and feed rates are great,” Johnson said. “The lifting power is phenomenal. We send steel into tight conditions where it would typically get stuck, but the lifting ability of the Geoprobe® pulled it right out.”
What’s happening downhole is no longer a mystery while using the 3100GT on a rocky moraine area with boulders to 75-80 feet or using the 3126GT on a hillside doing 100-foot rock coring where straight holes were imperative for installing the instrumentation.
“The coring features made it much more efficient and easier,” Johnson said. “The display screen assists the driller to know what is happening downhole and with the drill rig itself.”
And the extra engineering put into the mud pump system isn’t lost on the drillers.
“Now with two hydraulic pumps we’re not bleeding pressure from the flow,” Johnson said. “A lot of thought went into the design and the ability to control flow is really beneficial.”
Customer Feedback Prompts New Machine Options 3126GT and 3100GT: High Torque Rotary Head, Third Winch
While customers are proving the rock coring capabilities of the 4-speed rotary head on the 3126GT, some customers requested more bottom-end torque for their geotech jobs. True to form, Geoprobe® responded by designing the 6-speed GR6.5 rotary head with 70% more torque.
"The GR6.5 has 6,800 ft-lbs of torque, which is 2,800 ft-lbs more than the GR4.1 on a typical 7822DT, without sacrificing top-end speed (720 rpm)," Ryan Kejr, machine engineer lead, said. "We also added an additional intermediate-speed range, which further enhances the unit's wet and air rotary capabilities."
Another new option for both 3126GT and 3100GT is a third winch. With 1,100 lbs of line pull this winch is well suited to trip additional tooling out of the hole. Equipped with the Geoprobe® exclusive quick change hook, operators can switch over to wireline coring in seconds.
3126GT: 15-inch Lower Transport Height
Also new in 2021 is the folding winch mast option for the 3126GT for customers who prefer to haul their rig in an enclosed trailer or truck.
"This reduces the transport height of the 3126GT from 114 inches to 99 inches," Kejr said. "We accomplish this with a simple, mechanical ratcheting actuator. This is easily accessible from the ground when the drill mast is in transport position."
3100GT: Increased Payload Capacity Under CDL
With 22,000 lb GVWR, enjoy creature comforts of the fuel-sipping F600 chassis with additional payload to haul tooling all while remaining under class A/B CDL. Realize all the functional and power needed for your typical projects while adding ease of operation, expediting ability to advance helpers to drillers.
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Increased diversity and ability than a conventional rig, the 3100 series machines decrease time adjusting alignment which means increased time drilling with the power to pull steel out of tight conditions.