Three Rigs in One

Having put 8-9,000 hours on their conventional geotechnical rig, Terracon in Raleigh, North Carolina, determined it was more feasible to purchase a new rig rather than refurbish. In their new rig they sought the ability to expand into environmental (versus farming it out as they had the past 10 years) as well as into CPT (versus relying on the Charleston, South Carolina, or Greensboro, North Carolina, office). However, they needed something with more capability than a 7822DT since they see plenty of 150-foot holes. When considering the increased torque and ability to pull 20 feet of rod, a new 3230DT with a second hydraulic circuit for the mud pump best fit their needs.

“The second hydraulic circuit makes mud rotary much easier than the older 3230DT. We’re able to get more power out of the rig,” Willie Duggins, driller, said. “The new hydraulic pump improved production. Tier 4 power is integrated very well.”

They chose to add a rotation guard, which with other rig features combines to make a very safe and easy mud rotary drill to operate.

“It’s the most convenient rotation guard I’ve dealt with,” Duggins said. “The hydraulic hammer slides in, which is a lot easier versus manual. The telescoping mast makes a world of difference in tight situations in wooded areas.”

Compared to 2017 3230DT they used prior to their 2022 model being completed, Duggins finds coring and mud rotary 100 times easier with the two hydraulic circuits. In general, he finds the 2022 3230DT mud rotary drill doesn’t require fine tuning to do some tasks like the 2017 3230DT. He recently completed mud rotary to 150-feet collecting SPT samples and undisturbed samples in a historic Charleston greenway as part of a tunnel construction project.

“Working on the greenway, the 3230DT being more compact made it better suited to the job than a conventional rig,” Duggins said. “The 7822DT was a little small, but the 3230DT is more compact than our bigger ATV conventional rig.”

The budget planned two days per hole. However, the 2022 3230DT mud rotary drill took 1.5 days per hole versus the two days the 2017 model would have taken.

“We definitely increased production on these holes,” Duggins said. “When drilling deep holes with the old 3230DT, we’d sit and wait while water ran to clear cuttings. With the new 3230DT, we don’t have to sit and wait as long for hole to flush out because we’re not losing flow as we’re advancing the hole.”

Saving time allows them to bid jobs more competitively, getting the 3230DT mud rotary drill more in line with a dedicated geotechnical rig.

“On the projected 20-day job, saving a half-day per hole should shave five days off of original scope of work,” Duggins said. 

What they also gain with the 3230DT is three-rigs-in-one.

“We have all engineering-type rigs in one — environmental, geotechnical, and CPT — in a fairly compact package,” Duggins said. “The 3230DT is big by Geoprobe^® standards, but still a small footprint to most in geotechnical industry.”

They also gained industry-leading Geoprobe^® customer service.

“Customer service is my biggest thing and why there are very few drill rig companies I care for. Doug [sales manager] answered his phone on a Saturday when we had a breakdown and I was very impressed by that,” Duggins said. “He got me the answer I needed and minimized the time we were down on site.”