In 2015, Arizona Foundation Solutions helped restore the Historic Prescott Courthouse! Built in 1916, it is one of the few buildings on the Historic National Register. This restoration required innovative engineering and coordination between the Architect, Engineer and Arizona Foundation Solutions.
The mission was to raise all 4 of the giant stairs, landings, and attached stone walls at each entrance. They had sunk several inches, putting the granite stone steps and granite walls at risk from being damaged and also creating trip hazards. As it turns out all four of these staircases and landings were built on top of the debris of the Famous Whiskey Row Fire. This created a difficult environment to encapsulate and pressurize the soils to raise the structure back to its functioning elevation.
This remodel was required to be done 100% at night due to the fact the courthouse still functions at the counties main courtroom complex. This complicated the already innovative work in that any engineering adjustments would be required to be done by field personnel or wait until morning when no work could be done at the same time. We were told that if we disturbed the court rooms we could be held in contempt of court….. I don’t think they were kidding.
Much of the work was under the steps with low working heights and limited access and tight working conditions. 288 push piles were chosen over helical piles because of their versatility and ability to be installed in very tight access areas including a very low working areas using Foundation Supportworks low profile driving and lifting stands.
The west steps presented a monumental challenge as the weight of the structure included later additions of restrooms that could not have been accurately estimated from the information ahead of time. We lifted with the hydraulic cylinders simultaneously and grouted. The crews pumped grout for about 2 weeks every night with the pressures remaining steady but the structure lifting only marginally. We concluded that the grout was finding new voids in the debris as we continued to apply pressure. Gradually through a series of nightly lifts, allowing the grout from the previous night to harden, the structure was raised using a thixotropic admixture to facilitate blocking of voids.
The project was completed on time and under budget with none of the granite steps or giant blocks being damaged during the process.