- Workers had to bore precisely, from the towers to the foundation, without deviating more than 10mm from center.
- In an earthquake, the post-tension cables will compress the 800-million-pound landmark so it sways as one.
- Workers established a machine shop atop the temple to facilitate the vertical coring job.
Five years into the massive overhaul of the historic Salt Lake Temple, workers recently completed a three-year project to delicately drill 46 holes down through its stone walls.
Workers used diamond-edged drill bits to bore their way from the temple’s towers to its historic foundation in what was a precision job — the drilling could not deviate more than 10 millimeters from center.
The goal: Create vertical cores to make room for bundles of post-tension cabling that tie together reinforced steel structures added to the towers and roof above and to the major seismic upgrades in the historic foundation below.
The steel cables are tightened to half a million pounds.
Now if an earthquake hits the temple, the tension in the cables compresses the 185-million pound landmark together so that it will sway as one piece on top of a base isolation system under its foundation. The base isolators will separate it from the shaking ground.
To enable the vertical coring job, the West Coast Cutting and Coring Group built a fully equipped machine shop atop the temple.
“It seems a little crazy to set a machine shop on top of a temple, but we needed this operation to be right next to where we’re working,” WCCCG superintendent Ken Thornton said.
The hollow drill bits were attached to hollow drill rods five feet long and about two and a half inches in diameter. The diamond-edged drill bits were capable of boring through the quartz monzonite stone walls, but the system had to be able to stay on its tight target.
Workers found some voids in the walls and had to have a system that removed rubble. They developed a new low-flow operation to remove the water needed for drilling and the slurry caused by it without leaking into the temple’s interior.
The process cut more than two-and-a-half miles of stone cores.
Completion of the vertical coring is a major milestone in the renovation, which is expected to be completed in 2026.
The seismic work will continue through the first quarter of 2025 with continued tensioning of seismic systems in the historic temple, according to a news release issued by The Church of Jesus Christ of Latter-day Saints.
Most of the underground reinforced concrete structures for the addition around the sacred structure will be completed during the first three months of the year, the release said.
The public can view the renovation’s progress from the Main Street Plaza and the Conference Center across the street.
Much of Temple Square is open to visitors as the project continues, including the historic Tabernacle. For more information on building hours, visit TempleSquare.org.
Finish work is underway in the basement level of the expanded north addition.
Crews are also beginning to wrap up construction in the two baptistries, baptistry chapel, celestial rooms and sealing rooms, according to the church release.
The underground addition to the temple has an additional 300,000 square feet. The temple will have two baptistries instead of one and 22 sealing rooms (where marriages occur), up from 13. It will also have five instruction rooms with increased seating space.
Meanwhile, stone cladding work is being installed at the west entry pavilion on North Temple Street.