The CSO mitigation project includes a 5-mile (8km) main tunnel approximately 160 to 180ft (48.7 to 54.8m) deep in bedrock. There is another a mile of consolidated sewers near the surface connecting to drop shafts that will drop the combined sewage into the main the tunnel. There will also be approximately 2 miles of sewer that will connect to the south end of the tunnel that will be shallower and smaller in diameter.
