Challenging Earth Retention Solutions for the BJC South Patient Tower and Pedestrian Bridge Rebuild
Presenter: Lyle Simonton, PE
Director of Business Development – Subsurface Constructors
5:30-6:30 - Networking and Cash Bar
6:30-7:30 - Dinner
7:30-8:30 - Presentation
Topic:
As part of the Campus Renewal Program, BJC Healthcare is currently building a 16-story new patient care tower at the corner of Kingshighway and Barnes Jewish Plaza in St. Louis, MO. This site was previously the location of the Queeny Tower which was demolished in order for construction of the new tower to begin in late 2021. A phased opening is slated for 2025 to 2026. Construction of the new tower required a significant excavation in the footprint of the original building. Cut depths of the excavation ranged from roughly 18ft to 45ft and the excavation was bordered by Kingshighway to the west, Barnes Jewish Plaza to the north, and the remaining 18- story main BJC Plaza Tower to the east.
This presentation will cover two phases of earth retention for this project, the large excavation for the new tower, and support of the existing parking garage wall that remained in place while existing garage floors were demolished for construction of the new main hospital entrance pedestrian bridge. Subsurface Constructors designed and installed a four-sided earth retention system to support the large excavation, which ultimately required 169 solider piles and 3 levels of tie-backs for 138 total anchors. Aside from this site being very difficult logistically with major traffic along Kingshighway and the main hospital entrance, the biggest challenges consisted of designing a robust system to handle the 2,000kip building loads of the existing building that were supported on “wedding cake” shallow foundations that extended into the excavation. Additionally, during soldier pile installation, an old sheet pile wall with h-pile tiebacks was encountered in line with new earth retention, so design changes had to be made on the fly, including major changes to the basement of the new structure.
The second phase of earth retention shoring required Subsurface to install tie-backs/soil nails into the north wall of the existing parking garage on three levels using a low over-head tieback rig. The ties were connected with walers to hold back the existing wall as several floors were demolished so the general contractor could build the south abutment for the new pedestrian bridge, which would ultimately be the main hospital entrance. After the floors were demolished, the tie back rig was flown back into the cut so bottom level tie backs could be installed in the unstable shale. The design required 13 different tie-back layout iterations to make sure to avoid existing utilities and future drilled shafts for the pedestrian bridge.
Speaker:
Lyle Simonton is the Director of Business Development for Subsurface Constructors of St. Louis, MO. Lyle graduated from the University of Missouri-Rolla (MS&T) with a bachelor’s degree in Geological Engineering in 1997 and received a master’s degree in Civil (Geotechnical) Engineering from the University of Illinois – Champaign Urbana in 1999. He is a registered professional engineer in Missouri.
Lyle is a member of ASCE and DFI, and is currently on the Soil and Ground Improvement Committees for the ASCE Geo-Institute and the Deep Foundations Institute, respectively.
Lyle is a Past - President for the ASCE St. Louis Section, and has been an active member of the St. Louis Geo-Institute Chapter throughout his career. He is also current serving as the Membership Chairperson for the ASCE St. Louis Section and is an ASCE Mentor.
Lyle’s is on the Board of Directors and Education and Legislative Committees for the Southern Illinois Builders Association (SIBA). He also sits on the Professional Advisory Board for the Civil, Environmental and Infrastructure Engineering Department at Southern Illinois University – Carbondale.