Drilling Contractor Relies on Data to Optimize Blasthole Jobs
Design Blasting Services LLC, based in Murfreesboro, Tenn., often finds itself operating in urban settings. So, the precision — and the safety — of Atlas Copco’s FlexiROC and SmartROC top hammer rigs appeal to owner Brent Coleman and his crew.
“Our credibility is linked to safety,” Coleman said, “and our equipment, experience and quality establish that.”
The fuel efficiency of the FlexiROC T45 reduces costs and keeps rigs drilling instead of refueling — another reason Atlas Copco has earned its place on Coleman’s fleet. Design Blasting Services owns a SmartROC T40 and two FlexiROC T45 rigs, and they are renting a third FlexiROC T45.
Along with the safety advantages and fuel savings, Coleman also appreciates the rigs’ ability to record, track and document performance. “I can tell you at least 50 ways you can get in trouble on a job. There are just so many ways to lose money. But if you know your costs and data you’re in good shape.”
Each of their FlexiROC T45 drill rigs was at work on this particular day near Nashville. One was at a quarry opening a new section, and the other was with a SmartROC T40 line drilling a vibration buffer around the perimeter of what was to become a basement for an office building.
Design Blasting Services has moved up to higher-tech top hammer packages based on Atlas Copco’s Rig Control System (RCS) computerized “smart” rigs. The fifth generation RCS was launched in 2014.
“With an RCS-based rig you have a computer giving you data every day on each drill,” Coleman said. “That’s better than 15 people taking information, each recording it differently, and giving it to you whenever you happen to see them. Now, I just look at a computer and I get everything I need.”
It took just two days for the drillers to become familiar with the sounds, feel and high-tech processes of a smart rig.
Data tracking keeps Design’s fleet in optimum working condition, Coleman said. “We don’t overwork our rigs. It’s not just all about footage bonuses for us. It’s about the big picture. Overworking a rig causes downtime. Instead, we operate under a bonus structure with eight indicators, which prioritize things like maintaining the drill in addition to meeting drilling goals. Our guys see what we’re doing here.”
The rigs don’t just drill smarter but use much less fuel, a savings that Coleman can pass on to his customers. It is especially beneficial to a quarry client who supplies Design’s fuel as part of the drilling contract. “With other drills, we were drilling at about 35 cents per foot,” Coleman said. “But with these RCS-based FlexiROC and SmartROC rigs, we do the same work for less than 10 cents a foot.”
Driller Steve Majors pointed to drill history indicated on his display while working at the quarry. He was drilling shot patterns with a FlexiROC T45-11 to open a new section. “For example, this day I got 1,606 feet on 76.2 gallons, and on this one I got 2,201 with 70.0 gallons. It’s all right here in the computer. I can go back and look at the screen when I come back to this quarry.”
At a cost-per-foot comparison, Design Blasting Services saves the quarry about $1,500 a month. And the rigs spend more time drilling and less time refueling, so productivity is higher. “With other drills I’d need fuel after 1,200 feet with the air turned up,” Coleman said. “On average, now I can get 800 feet more with same air on the FlexiROC T45.”
“This modern T45 can drill two full days on a single fill,” Coleman explained. “Each time you have to tram off a bench, you lose about four hours’ drilling time. Being able to drill up to an additional 500 feet per day is a big difference.”
“We’ve got an Atlas Copco service location very close, but even so, rig dependability is still important,” Majors said. “For five drill jobs in a row now, all on different formations in different parts of the state, I’ve had zero downtime. Not one minute. Those jobs included 30- to 75-foot holes at 4 to 5½ inches, sandstone and limestone, on T51 steel.”
The T45 rig’s boom extends to drill multiple holes without moving on the pattern, which means less time is spent relocating to set up on holes, more on drilling them. Patterns and hole size vary according to location and formation, so the drill adapts better than others in this application.
In soft formations this drill has completely outperformed other drills. “Formations like clay and dirt are tough on a drill,” Majors said. “Before six months was up on a previous drill, I lost count how many steels I broke — at least 24. But in more than twice that time — 13 months — I’ve only had three broken steels with this drill. And the other guys we’ve got running Atlas Copco rigs report the same. We can’t all be that good.”
The drill compensates for a bad formation, according to Majors. “Most drills will plug up the bit — too much air and automated control on the down pressure. In 30 feet of dirt, another drill would get hung up, but not this drill. This drill will get the same footage over time on any given pattern, regardless of formation changes, no matter what. Autodrill is a handy feature. The rig drills well without it, but this machine will do all the work for you, when you let it.”
“This is absolutely the best drill I’ve ever run,” Majors said. “There just aren’t any comparisons, and that’s the truth.”
His 20 years of drilling kept him from being easily won over. He pointed out several features that impressed him. “The anti-jam feature is great. You don’t have to feather through. It knows when you’re on a fracture or moving though incompetent formations. By instantly slowing down, it not only prevents dry-firing on the hammer and steel but also keeps the hammer from pushing too fast, which could cause the bit to get stuck or cave in a borehole.”
Working back on the construction site on the vibration buffer, the task had taken about two weeks, progressing at a rate of about 2,000 drill feet per day. The 4-inch-diameter buffer holes were spaced 1 foot apart to a depth of 47 feet. Water encountered at 20 feet was filling the holes under pressure by 40 feet but did not present a problem while drilling.
The plan required removal of 130,000 yards of material, creating a hole whose floor was approximately 50 feet below street level. After the first 5 feet of overburden had been removed, three 15-foot lifts were drilled and blasted to remove the rest of the material.
The main area blasthole pattern consisted of 3-inch-diameter holes with 6-by-6-foot spacing. The perimeter pattern was 1½-inch holes in 3-by-3-foot spacing.
Ten seismographic sensors were placed around the project to document impact of the blast on the surrounding environment. One of the sensors was in a nearby bank. Two more were placed in an office building close to the worksite.
A 300-foot stretch of road surrounded the project. Thirteen locations on the project were close enough to it to require blockading the road, preventing traffic and passers-by from coming too close to a blast. Blasting could take place at 6 a.m., 10 a.m. or 2 p.m. The earliest time was preferred since it was less congested at that time of day and nearby businesses had not yet opened.
Design Blasting Services appreciates concerns about blasting in urban settings. The company’s professionalism and state-of-the-art equipment helped to reassure residents.
“This is our specialty,” Coleman said. “We do jobs like this all over. It may look extreme performing blast operations in a city like this, but we are very particular about what we do. It’s all very planned out.”
Coleman said his choice in manufacturer didn’t just give Design Blasting Services drills with more capabilities. “We like Atlas Copco because they look at how they can make us successful. When we need something, they are there. Kenneth Long, service manager, and all the service technicians at the Nashville Branch are phenomenal. For training and service on these smart rigs, Atlas Copco made the learning curve a lot shorter.”
This story originally appeared in Mining & Construction USA magazine.