Project Type: Underpinning
Location: West Valley City, Utah
Date: November 2008
Description: The Utah Transit Authority's TRAX light rail system is designed with "hubs" throughout the valley for the Wasatch Front commuters. West Valley City's hub is located on a site directly adjacent to the City Hall building.
To accomplish their plan, UTA needed their TRAX cars to be within 4 feet of the 8 year old building. Intermountain Helical Piers was asked to participate in the planning and construction. Underpinning of the existing City Hall building and piers for support of the 6 foot retaining wall were engineered. An extra challenge accompanied this project, as the City Hall building had experienced settling over its short life. The building is a steel structural frame with glass and brick veneer panels as the exterior skin. The city managers were concerned with raising the building to correct the settling because of the sensitive glass skin and potential for damage during the lifting. With precise care and pier placement, the structure was underpinned at the column load areas and hydraulically lifted to the proper level. This relieved the pressure on the structure's steel frame and no glass panels were broken or even cracked. Once the structure was secured by the helical pier underpinning, new construction piers were installed for the retaining wall needed by the TRAX rail system and the City's transit hub.