Thrasher Foundation Repair Case Studies: Lund Ross & J-Development - Swivel

Monday, December 14th, 2020 by Kendra Dunnigan

Challenge

J-Development Company purchased a 25,000 square foot property on 72nd and Dodge to renovate. This project, known as Swivel(opens in a new window), will feature 158 apartments with commercial space and is set to open in midtown Omaha in 2021.

The existing structure consisted of a single-story building with a basement level. The existing building will be converted into a two-level parking structure, commercial space and an additional four stories of apartments to be constructed on top of the existing structure. Lund Ross was the General Contractor on this project, with TD2 providing engineering support and Terracon acting as geotechnical consultant.

The additions next to and on top of the building would introduce additional load beyond what the existing structure and site soil conditions could support using traditional spread footing construction. A ground improvement or deep foundation system was required to build off of. New footing column pads and grade beams would be added in the basement and the exterior of the building in order to support the additions. The existing basement has an overhead clearance of 10 feet, therefore the deep foundation options likely consisted of micro piles or helical piles.

Because the architect and design team chose to leave the building’s shell in place, it dictated several access conditions that would ultimately influence the solution.

Solution

Helical piles were chosen due to various obstacles and access conditions. Other ground improvement and deep foundation systems would not have worked in this configuration. We were also aware of overhead and site access restrictions and not disturbing the existing building foundation. We used 5-foot material because of the tight underground access.

Thrasher was selected to perform the install and our commercial team worked with the design and engineering teams to build a helical pile design. The design consisted of 307 total helical piles. Helical piles would serve in compression and tension support of all new column pads and grade beams. Helical pile allowable loads ranged from 40 kip to 112 kip per pile. Approximately 60 pile cap configurations were installed to depths on the range of 40 ft – 80 ft in length to achieve required capacity. Two sacrificial full-scale load tests were performed in order to validate the pile design.

Two install crews (5-6 crew members each) worked on the project and on average installed 15 piers per day. There were various multiple load requirements. Each of the pile caps was unique in the load it needed to handle.

During the project, we also were able to help stabilize the wall on the northeast side of the property. There was a limited amount of space between the wall and the proposed foundation. The wall needed to be stabilized and the soil, retained. Thrasher was able to shore up the wall utilizing Soils Nails (essentially horizontal Helicals) driven 14 feet into the ground. We then tied in a rebar grid and covered the surface with a layer of ShotCrete – blown concrete, to create a permanent wall feature.

Results:

We accomplished the project as scoped. Overall, it was a highly successful installation. The challenge was the tight spacing. We are often asked to perform under similar conditions and are starting to get a reputation for executing the improbable. This was one of the larger helical projects that we have done and is a testament to the reputation we’ve earned for our ability to deliver.

“It’s a pivotal project, and one of the first, to begin the revitalization of the Crossroads area,” said Todd Royal, Thrasher Solutions Specialist & Project Lead. “This is an example of a “cornerstone” project for us. Years from now, we’ll drive by that location, knowing that people are living (safely) because of the work we completed there.”

Thrasher Production Manager Brent Foreman added,

“Helical piles ultimately proved to be the best deep foundation design for the project. Helical piles are cost effective, minimally invasive, do not generated spoils, require a small footprint, can be installed in tight access conditions, efficient installation processes and allows footing teams to place reinforcement and concrete immediately once pile is installed.”

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. 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 is the right partner for the job. Much of Thrasher'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.