Rock Mechanics Engineer for ARUP Reza Ghasemi and LBNE Project Director Jim Strait inspect a rock core at the Sanford Lab. The core comes from the level that will be excavated to house the LBNE far detector. Photo: Matt Kapust, Sanford Underground Research Facility
Nearly a mile underground, a drilling crew is working around the clock to extract rock core at the Sanford Underground Research Facility in Lead, S.D. Core samples are used to explore the rock mass that would house the proposed Long-Baseline Neutrino Experiment liquid-argon far detector.
Last month, LBNE project staff went underground to observe the geotechnical work.
“We wanted to kick the tires, learn how it works and see the drilling process,” said LBNE Project Director Jim Strait.
It’s the first activity at Sanford Lab in preparation for the anticipated LBNE project, said LBNE Conventional Facilities Manager Tracy Lundin. The exploration program is intended to characterize the rock mass. Core samples can tell engineers about the rock’s strength and geologic composition. They can also reveal the orientation of folds and other imperfections in the rock mass, all of which can influence the design of the excavation that would house the detector.
LBNE would aim a beam of neutrinos generated at Fermilab to an underground detector at the Sanford Lab, 800 miles away. “It’s a lovely distance,” said Strait. “It’s in the sweet spot we need to efficiently study neutrinos.”
Drilling subcontractor First Drilling is creating four exploration holes on the 4850 Level — the level 4,850 feet below the surface — yielding 3-inch-diameter rock cores hundreds of feet long and taken out in 5-foot sections. Engineering firm ARUP is logging and packaging it in boxes for later testing at a geotechnical laboratory.
First Drilling set up a 1970s-era Conner 208h core rig for the job.
“It may be old but these babies get the job done,” said Mike Kukar, drill supervisor.
The rig had to be properly configured to fit in the narrow 8-foot drift, or underground tunnel. A generator set up behind the drill powers the rig, which uses a hollow diamond-tipped bit that cuts through the hard rock and leaves a solid rock core sample in its wake. It takes 8 to 12 gallons of water per minute to lubricate and flush out the borehole. Kukar said it was one of the most extreme setups he’s had to arrange.
Kukar left a good impression with LBNE’s Environment, Health and Safety Manager Mike Andrews. Kukar’s first conversation upon entering the work site was a thorough safety briefing.
“You just knew that safety was number one when managing this site,” Andrews said. “I’m extremely happy with what I saw in the drilling project safety program.”
Sanford Lab Executive Director Mike Headley said he was happy to host the LBNE staff and is pleased the drilling project is ahead of schedule.
“Without the investment from South Dakota it might not be possible to construct LBNE in the United States,” Strait said. “It’s amazing that such a small state would make this tremendous investment in basic science.”
Matt Kapust is at Sanford Underground Research Facility.
Editor’s note: A version of this story appeared in Sanford Underground Research Facility’s Deep Thoughts.