Provo City Center Temple
History was changed forever in Provo, Utah when the historic Provo Tabernacle, originally constructed in 1883, was gutted by a four-alarm fire.
It remains unclear what started the blaze, but the night before the fire, crews were inside of the building filming a rehearsal for a popular holiday production.
Residents were devastated by what appeared to be the end of the story for the Tabernacle, which served as an extremely important part of the community’s heritage and a centerpiece for the Church of Jesus Christ of Latter Day Saints (LDS.) The fire was so devastating it left nothing more than the rubble foundation and the brick façade somewhat intact. Community members waited anxiously for leaders of the Church, local engineers and authorities to meet and determine the fate of the popular building.
Church leaders decided to save the building and a short two years later approved the plans that gave the Church the needed space to construct an impressive new structure. Additionally, church leaders determined that the structure would be rebuilt as a Temple.
Background
Background
Intense preservation and design work were required in order to begin construction on the new Provo City Temple.
Great care was taken in the designs to preserve the original historic beauty of the church’s exterior. The interior components were modeled after the originals.
The original limestone foundation, which was four feet thick and five feet deep, was removed and the excavated stone was donated to the city of Provo.
The site is located in the Wasatch Range of alluvial fan sands and gravels overlying very sensitive lacustrine clay deposits. The surficial water table was nearly 20 feet below existing grade. These conditions created an environment that required closely coordinated construction efforts and tight tolerances on dynamic variables.
The Work
The Work
Nicholson was tasked with developing and constructing an elaborate underpinning system so that two levels of basement could be constructed below the structure.
This work also included the construction of a support of excavation system around the entire complex and a groundwater cutoff wall and dewater system around the new Temple. The underpinning system was monitored by Nicholson’s sister company, Soldata, to assure that the performance was consistent with the design expectations.
Work began with the installation of 140 temporary 12-inch micropiles, which were installed to a depth of 90 feet immediately adjacent to the mortar and cobble foundation. Sections of the original foundation were removed and twin “needle” beams were installed at 56 locations, supported by the micropiles. The piles were then pre-loaded with hydraulic jacks.
It was then a surgical and intricate excavation process around the site to excavate 25,000 cubic yards around the building as welders and steel workers braced the exposed piles.
A 710-foot long, 53-foot deep cutoff wall was constructed using a mixture of existing soil, cement and bentonite slurry outside the footprint of the structure in 72 hours.
This trench effectively created the sides of a bathtub around the building to hold back the water as the second phase of excavation below the original water table began.
Four dewatering wells and two monitoring wells were installed during this hustle to drain the tub in concert with the excavation. The cutoff wall stopped the dewatering effort from extending beyond the basement to not consolidate or overstress the sensitive clay, which would cause significant settlement of adjacent properties. The next tier of bracing was installed and the remaining 20 feet of soil was excavated.
Arriving at design grade, 390 permanent piles (on two-foot centers) along the perimeter were installed to support the basement walls of the Temple. Additional items in the scope included the installation of a 20-25 foot deep beam and lagging retaining wall with tiebacks around the two city blocks’ perimeter. In areas that were below the water table, jet grouting was used as the lagging in order to control the inflow of groundwater.
To see and learn more, take a virtual tour of the Provo site with Jonathan Dwight.
The Result
The Result
The Temple took 43 months from groundbreaking to be completed. It was finished almost five years to the date of the inferno that almost destroyed it forever.
It opened its doors to hundreds of thousands of visitors eager to see the newly renovated structure, which includes four levels—two above and two below ground, plus an underground parking garage.
Despite dealing with incredibly challenging conditions, the work for this high-profile project was completed on schedule, with a high-level of interest and gratitude from the local community.
This was a once-in-a-lifetime project. To be part of the team restoring something that meant so much to this community was an honor and one none of us will soon forget.
RICK DESCHAMPS, P.E., Ph.D
Vice President of Engineering
