Massachusetts Water Resources Authority
North Dorchester Bay CSO Pump Station
Location: South Boston, MA
Completion Date: March, 2010
General Contractor: Walsh Northeast
Vital Statistics: Project Value: $2,180,000.00
Wall Type: 36" Reinforced Concrete Slurry Wall
Wall Area: 24,650 S.F. Max.
Max. Excavated Depth: 97'
The CSO Pump Station required a 60' deep excavation in soft soils. In order to facilitate the construction of the complex reinforced concrete structure of the Pump Station, it was desirable to have an un-braced lateral support of excavation. Easement restrictions would not accommodate a circular slurry wall and therefore the support of excavation was achieved with an elliptical slurry wall. Because of the same restrictions, the main axes of the ellipse had to be skewed with respect to those of the pump station. Tensile stresses at the inner face of the slurry wall that were expected to develop along the flat side of the ellipse, at the higher elevations, required the installation of welded stitching plates across selected panel joints.