Each day, a diverse set of case studies will be presented by experienced geotechnical professionals. Each session will run approximately 2 hours with opportunities to ask questions. Registrants can earn 1.0 Professional Development Hours (1.0 PDHs) for each event viewed.
The Geo-Institute Technical Committees will be live streaming the Soil Improvement Technical Committee Tuesday, December 8 at 2pm EST. Keller's Joseph Mann will be presenting on:
“Challenges of a dry excavation on the shore of the Potomac"
Despite the challenges of working on the Potomac River adjacent to historic buildings and the disruption caused by the discovery of a buried old ship's hull, a watertight earth retention system (ERS) was constructed on time and with minimal movement of adjacent structures.
Robinson Landing is a $185 million, mixed-use development that covers a full city block on the Potomac River waterfront in Alexandria, VA. Subsurface conditions consisted of interbedded layers of silty sand and gravels, soft lean clay, and stiff fat clay with a near surface groundwater table. The planned structure includes two levels of below-grade parking supporting a five-story above-grade condominium building. A “bathtub” cut-off structure was needed to provide a dry excavation while not impacting surrounding properties through dewatering-induced settlement or migration of contaminated groundwater. Early in the work, a buried historic ship’s hull was detected partially within the 50,000 sq. ft. building footprint at a depth of 25-ft.
The internally-braced, vertical, soil-cement TRD perimeter cut-off wall was constructed to a depth of approximately 80 ft and keyed into the underlying marine clay. The TRD wall was designed to function as both a permanent cut-off and temporary ERS and eliminated the need to design for uplift pressure or for external perimeter dewatering.
Following detection of the ship’s hull, the shoring was redesigned to facilitate inspection and safe removal of the hull without impacting the project schedule.