Crews are on scene in South Boston Friday morning where a water main has been shut down at Dorchester Ave. and D Street. The Boston Water and Sewer Commission said excavation was underway, with multiple services affected. Stream NBC10 Boston news for free, 24/7, wherever you are. WATCH HERE WATCH HEREBWSC crews shut down water main at Dorchester Ave and D St SBos, Excavation is underway. Multiple services affected.