Landmark Center Phase 3

GeoEngineers’ Construction Design team partnered with Trevi Icos Corporation of Charlestown, MA, to provide excavation support design for the 421 Park Drive (Landmark Center) redevelopment in Boston, MA. This 14-story, mixed-use life science project includes laboratory, office, grocery, and parking space. GeoEngineers’ scope included the design of a slurry wall and internally braced support of excavation system.

Approach

• Designed support of excavation (SOE) for a 350-by-200-foot excavation reaching depths of up to 40 feet to accommodate the project’s basement and three levels of underground parking.
• Implemented a 36-inch-thick slurry wall system with three levels of internal bracing; internal wales supported two long sides, while external wales were used along sides adjacent to existing buildings.
• Performed detailed analysis of potential excavation impacts, including settlement effects on nearby structures and transit facilities.
• Conducted finite element modeling for staged excavation and developed innovative “subgrade strut” approach to control settlement in soft Boston Blue Clay.
• Configured bracing to avoid proposed elevator shafts and shear walls and phased excavation to maintain access for adjacent property deliveries.

Results

GeoEngineers delivered complete design calculations and detailed construction drawings for the temporary support of excavation (SOE) system. The design package included typical plans, cross sections, material specifications, bracing configurations, and staged construction sequencing. These deliverables provided the contractor with clear guidance to safely construct the basement and underground parking levels while protecting adjacent structures, enabling efficient excavation and minimizing settlement impacts in a challenging urban environment. The excavation performed as expected based on monitoring data and was successful in protecting adjacent buildings.