By Nancy Miller Chenier
Construction of the Combined Sewage Storage Tunnel (CSST) under Lowertown, which is part of the Ottawa River Action Plan, is scheduled to begin later this fall. The proposed east-west tunnel will start in LeBreton Flats and proceed through the downtown core, moving along Cumberland Street to near Cathcart, and then angle to Bolton and under King Edward Park and the Rideau River to the outlet in New Edinburgh Park. (See the map below.)
The tunnel, which is approximately three metres in diameter will run anywhere from 10 to 30 metres below ground level. Its role is to hold sewer overflow during major rainfalls. It will reduce the frequency of sewage overflows directly entering the Ottawa River by allowing the excess surface runoff and wastewater to be stored until it is treated.
The long-term environmental benefits for the river are expected to be significant. The short-term consequences for Lowertown residents are to be tolerated for the greater good. They began and continue with the noise reverberating across the Rideau River into Bordeleau Park as the holding chamber and tunnel shaft are constructed. For residents above or near the tunnel route, there may be noticeable vibrations as the tunnel boring machine passes underneath. These are to be monitored by the contractor to ensure that they are within non-damaging limits.
The CSST team plans to update the Lowertown Community Association before tunneling reaches Lowertown and to continue to share information on its website. In the meantime they are providing regular updates through a project newsletter and can be reached at their email csst@ottawa.ca