Charlestown Bus Facility – Shoreline Stabilization & Yard Improvements
Massachusetts Bay Transportation Authority
The MBTA’s largest bus facility is located along the tidally influenced Mystic River, separated from the water by a deteriorating sheet pile seawall. Behind the seawall exists a 345kV buried transmission line that is a major electrical trunk line for eastern Massachusetts.
Considering the transmission line, the poor soils, and the life cycle costs of a new steel bulkhead, the engineers ruled out a replacement of the seawall and designed a new natural shoreline constructed over stabilized subsurface soils. The stabilization consists of a vast grid of soilcrete columns installed via jet-grouting techniques into the deep clay layers under the river. Atop the soilcrete columns a new shoreline embankment will be constructed of natural stone lifts with geosynthetic fabrics and geogrid panels. The project also includes upgrades to the drainage system, dredging of the river bottom, and the construction of a new flood wall to provide hurricane resiliency to the facility.