Helical Piles Used to Restore Historic Building in Great Falls, Montana
In 2009, a fire compromised the integrity of several floors of the Rocky Mountain Building in Great Falls, Montana. Built in 1914, The Rocky Mountain Building was the previous home of the Rocky Mountain Fire Insurance Company, the Pantages Theater, and a Public Drug store. Ever since the fire, the building has been left vacant. The building was such an eye-sore that many locals asked why it wasn’t torn down.
To save the piece of Great Falls history, Alluvion set out to build a state-of-the-art, full-service clinic optimized for the patient’s needs. They worked with Nelson Architects and the Sletten Construction Company. Breaking ground in 2022 there was a 29 million-dollar budget for phase one. Gittins Foundation Specialist Inc. installed all the drilled and grouted pull-down ECP helical piers to provide structural support to the interior load-bearing columns. Each ECP grouted helical pier was driven to 30-35 feet below grade. Here they developed a load-bearing capacity of 100 kips.
The teams faced minimal access to the charred building site. All equipment and products had to be craned into the basement of the four-story building. On top of this, there was limited headroom for
the installation of foundation elements. The Geo tech investigation revealed that the soils encountered at bearing elevation are very weak and compressible yet expansive. This, coupled with the magnitude of the anticipated foundation loads for the project, led the Structural Engineer, Geotechnical Engineer, and General Contractor to the decision to use grouted helical piles.
With the design team, comprising Thomas Dean & Hoskins Engineering & Geotech, and consultation from Gittins Foundation Specialist Inc., both on the same page, they proceeded with installing ECP TAF-175-84 with a 10/12 Helical flight and a 6-inch diameter grout ring. The grout ring, made of steel, was placed just below the coupler. This allowed the grouted columns to continue to a load-bearing stratum target depth of 30-35 feet. After reaching the target depth, the concrete piles were capped with new construction pier caps with number 6 rebar full cages.
After completing another in a long line of helical projects, Gittins Foundation Specialists described Earth Contact Products as “the very best” and “the finest engineered foundation restoration products in the industry.”