Helical piers overcome soil problems in Regional Transportation District (RTD) project

Architect: RNL Architectural
Geotechnical Engineer: Kumar & Associates, Inc.
Structural Engineer: AECOM Structural
General Contractor: White Construction Group
Certified Installer: Complete Basement Systems, Inc., Aurora, CO
Products Installed: 80 HP350 helical piers

RTD Denver, Colorado

Serving Denver, Colorado and surrounding communities, the Denver Regional Transportation District (RTD) is one of the most extensive and most successful mass transit systems in the U.S.

Incorporating bus and light rail (passenger only) service, the RTD system links the city center with outlying suburbs and brings travelers and commuters to other transportation hubs like the Denver airport and Amtrak terminals.

When Complete Basement Systems was contacted to collaborate on a new construction project for the RTD, we knew that our work would be challenging, interesting and important.

The planned RTD building, designed by Denver-based RNL, will serve as a large wash bay for RTD light rail trains, and be located directly adjacent to nine train tracks.

The Challenges

One of the first challenges for the CBS crew was to undergo a special training program simply to cross the tracks and access the site.

A careful soil analysis was very important for this project since the concrete slab floor of the building and the soil below would need to support the significant weight of train cars moving in and out of the building. The firm of Kumar & Associates performed a geotechnical survey to assess soil characteristics at the site.

The results of this soil analysis indicated the presence of fill soil and other soils with marginal stability and load-bearing characteristics.

The Solution

RTD Denver, Colorado

In collaboration with structural engineers (AECOM), Complete Basement Systems determined that a total of 80 helical piers should be installed beneath the poured concrete slab and foundation walls. Helical piers were selected because they can be installed safely and effectively in a confined area like this one.

The model 350 helical piers used for this project have an outside diameter of 3.5 in. and a triple-helix lead section. The CBS crew managed to complete the installation of 80 piers in just eight days, completing their work two days ahead of schedule. Pier depth ranged from 18ft. to 25ft.

As shown in the photos, the square flange on the top of each pier is surrounded by substantial steel reinforcement for the poured concrete slab and walls.

This well-engineered, expertly installed structural system ensures that the building will handle heavy loads without shifting or settling.

Complete Basement Systems offers comprehensive foundation improvements in Castle Rock, Fountain, Monument, Woodland Park, Palmer Lake, Larkspur, Sedalia, and Colorado

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