Massachusetts Water Resources Authority
North Dorchester Bay CSO Storage Tunnel Access Shafts
Location: South Boston, MA
Owner: MWRA
Completion Date: March, 2007
General Contractor: Shank/Balfour Beatty/Barletta Engineering JV
Vital Statistics:
Project Value: $3,585,000.00
Wall Type: 30” and 36” Reinforced Concrete Slurry Walls
Wall Area: 27,100 S.F.
Max. Excavated Depth: 130’
Project
Description:
A new 17’ diameter CSO Storage Tunnel, 2 miles in length, along Dorchester Bay in South Boston and a future pumping station are part of Boston’s Inner Harbor clean up program. The TBM used to excavate the tunnel required a 50’ diameter access shaft and a 34 diameter retrieval shaft. Slurry walls, constructed as a decagon and an octagon respectively, were used as the outer shells of the shafts, to provide an un-braced lateral earth support system and were installed in soft ground conditions. The slurry wall for the main access shaft was keyed into the underlying Argillite rock formation.
