Commercial Solutions Case Studies: Mixed Used Building Retrofit in Urbandale, IA is the Perfect Fit for Helical Piers

Monday, March 15th, 2021 by Jay Liebenguth

Challenge

A building in Urbandale, IA(opens in a new window), was being renovated to allow for more usable space to accommodate a service center. The solution will support additional mezzanines and mezzanine renovation on existing column foundations and new spread footing foundations.

The building was an existing office building converted into a service center of sorts, so a general reconfiguration of the building use and layout. The plans called for additional support columns to support the roof and size up the existing support columns to better disperse new structural loads.

Challenge:  

The existing structure would not support the additions next to and on top of the building. The site soil conditions were not strong enough to support the additional loads using traditional spread footing construction. A ground improvement or deep foundation system was required to build off of. Additional loads ranging from 20-25,000 lbs. (20-25 kip) will be needed.       

We worked within the existing building's infrastructure, so helicals were ideal to limit vibration, soil disturbance, and the potential need for over-excavation. We also had some interestingly tight overhead clearances to work around, with the 2nd-floor mezzanine staying intact during installation.

The existing structure would not support the additions next to and on top of the building. The site soil conditions were not strong enough to support the additional loads using traditional spread footing construction. A ground improvement or deep foundation system was required to build off of. Additional loads ranging from 20-25,000 lbs. (20-25 kip) will be needed.       

We worked within the existing building's infrastructure, so helicals were ideal to limit vibration, soil disturbance, and the potential need for over-excavation. We also had some interestingly tight overhead clearances to work around, with the 2nd-floor mezzanine staying intact during installation.

Solution

McGough Construction(opens in a new window) contracted with Thrasher to provide preliminary design and job costs for an intermediate foundation system to support the renovations. Dan Packard of Packard Engineering designed the deep foundation system. It was a mixture of new construction helical piers and retrofit helical piers, totaling 147 piers needed. 

The design consisted of 74 new construction helical piles to support new spread footings and 73 retrofit helical piles to support the existing column pad footings. Utilizing a 10 and 12-inch helical lead section and hollow round shaft extensions, Thrasher advanced the helical piles to an average of 35 feet to achieve the required capacities. The Thrasher crew performed two sacrificial full-scale load tests to verify pile capacities before production piles were installed. Utilizing two pieces of install equipment and a crew of six, Thrasher installed the 147 helical piles in eleven days plus two days for load tests.   

Our work was scheduled right around the end of the year holidays, and the overall project schedule relied on Thrasher being quick on installation. We had two crews running for most of the project, getting as much steel in the ground as possible each day. This project was an example of a robust and diverse engagement regarding technical ability, product, installation, and working with and around other trades.

Thrasher Commercial Production Manager Brent Foreman said that this job's site footprint was perfect for helical piles. "Helicals were truly the answer for this project due to the various obstacles and access conditions. Other ground improvement and deep foundation systems would not have worked in this configuration," Foreman said. "We were also aware of overhead and site access restrictions and not disturbing the existing building foundation. The crew performed well to get this project in the ground in an aggressive timeframe," he added. "We had crews following us as quickly as we drove the helicals. They were tying in their rebar cage and pouring footings."

Results:

General Contractor McGough Construction Senior Superintendent Chuck Carpenter had this to say about working with the Thrasher team. "I received excellent communication from them. The workers were very respectable and always made time for my questions. (Your crew) was always working, never seemed to be downtime, which is a great thing!" He also praised the coordination with third-party vendor Terracon as "seamless." Terracon monitored the load test, installation depths and torque. They also signed off on final pier elevations.

Thrasher Project Manager Shannon Lewis said of working on this project, "It felt like a partnership, not just a transaction. The entire McGough team was responsive, transparent, flexible, and fun to work with. I felt like we had learned a lot from each other during this project and that we built a solid foundation for a budding relationship moving forward."

If you have a project that includes a deep foundation system or shoring up walls or slabs, you owe it to yourself to call Thrasher Commercial. Suppose your project needs include Helical or Push Piers, Grouted Micropiles, Polyurethane Foam, Cellular Concrete, Grouted or Mechanical Soil Nails, Helical Tie Backs or Geo-Lock Wall Anchors. In that case, Thrasher Commercial is the right partner for the job. Much of Thrasher Commercial's portfolio of work involves permanently stabilizing new and existing structures. We work throughout the 4-state region that includes Nebraska, Iowa, Missouri and Kansas.

For more information on how the Thrasher Commercial can deliver exceptional results to your commercial project, give us a call at 800-827-0702 or learn more here.