In the past month, the Salt Lake Temple has begun a major seismic strengthening process called “jack and bore” as steel pipes are inserted below its existing foundation.
The September 2021 renovation update on the Church’s Newsroom explained this process and provided additional information about excavation and truss installation. The Salt Lake Temple renovation project began at the end of December 2019 and is expected to take four years.
‘Jack and bore’
The first steel pipe was inserted in late August under the east towers. A total of 92 pipes — 40 feet long and 3.5 to 4 feet in diameter — will support the temple’s foundation.
The soil is removed, initially by hand, from inside the pipe as it is gradually inserted horizontally, according to the news release. The gap between the outside surface of the pipe and the surrounding soil is then filled with grout. Once installed the pipes will be filled with reinforced steel, including post-tensioning strands and high-strength concrete.
Excavation has continued on the north side of the temple past the level of the entrance tunnel, providing space for three new underground floors, which will be used as an addition to the temple.
The tunnel will connect the Salt Lake Temple to the underground parking garage in the Conference Center to provide safer and easier access to those visiting the sacred edifice.
Two new trusses were installed on the roof of the temple, and three of the eight areas, or bays, have been completed as part of the truss installation. To protect the interior finishes of the building, the roof is closed each time new trusses are installed.
The secant wall that acts as a retaining wall around the temple continues to be excavated to prepare for the three future floors underground in a temple annex and to contain the soil under the temple.
Read more about the Salt Lake Temple renovation at TempleSquare.org.