View of the Ottawa River from Ontario, looking over the Portage Bridge.

Project Update

Combined Sewage Storage Tunnel (CSST)

The Combined Sewage Storage Tunnel (CSST) project will help protect the Ottawa River for future generations. Read on to find out how construction is progressing.

Construction Forecast - Sites on your radar

The map below identifies construction sites for the CSST project within the City of Ottawa. Construction has either started or activities are imminent at the sites indicated in green. The red dots indicate future construction sites. Site 7, identified with the grey dot, was eliminated during the design phase of the project.
Tunneling activities for the North-South Tunnel are anticipated to start at Site 10 by mid 2017. 
Below is information regarding project sites that are currently active:
Map of the CSST sites numbers 1 to 10. Sites 5, 6 and 10 are green, site 7 is grey and all other sites are red

Site 3a: Rideau Canal Interceptor Diversion/Drop – Confederation Park

Some advance construction activities took place in Confederation Park in 2016 and the site was re-instated for full use. Once the CSST is operational, this chamber will re-direct flows from the Rideau Canal Interceptor to the CSST, reducing overflows going directly into the Ottawa River.
Winterlude is taking place in Confederation Park from February 3 through 20, 2017.
Construction will resume in 2018.

Site 5: East West Tunnel Outlet/Rideau River Collector Diversion – Stanley Park/New Edinburgh Park

Stanley Park will eventually be the site of the East-West Tunnel Outlet and Rideau River Collector Diversion.
Some advance work was completed in the vicinity this fall and winter, including:
  • Hydro Ottawa installed underground conduits along Crichton Street and Stanley Avenue that will eventually provide power required for construction activities in Stanley Park.
  • Archeological work in Stanley Park, consisting of small localized excavations, took place as the area was identified as having a heightened potential for an archeological find during the initial planning phases.
  • Drilling activities were completed in late November 2016 to locate the existing interceptor outfall sewer that goes under New Edinburgh/Stanley Park.
  • Soil sampling was completed in January 2017 to determine the baseline soil conditions in Stanley Park.
Construction activities will begin in the first quarter of 2017 at this site. This work will include some tree clearing in Stanley Park and initial mobilization activities, including construction fencing and equipment, in both Stanley Park and at the intersection of Queen Victoria and River Lane.

An Open House with the project team is scheduled for February 22nd (drop-in between 5:30pm and 7:30pm) at St. Bartholomew Church (125 Mackay St). At this Open House, residents will have the opportunity to:
  • Review background information on the CSST Project
  • Learn about the expected noise levels during construction
  • Review construction activities occurring in Stanley Park
  • Provide input into the selection of truck routes through New Edinburgh
Additional information on the Open House and upcoming construction can also be accessed at
Soil Sampling
Soil Sampling
Archeological work in the area
Archeological work in the area

Site 6: North South Tunnel (NST) Overflow/Kent Street Outfall - Ottawa River Pathway

This site will be the exit point for the tunnel boring machine traveling northward from Site 10 (Kent and Chamberlain). It will also be a permanent access point to the CSST once complete.
Tree clearing is scheduled to begin in late February. The trees are being removed early in the year so that the work occurs outside of the general nesting period for breeding birds, which is recommended by Environment Canada.  The pathway along the Ottawa River will be open and useable while this work is being undertaken.
Further to the tree removal, construction activities at this site are anticipated to begin in June 2017.

Site 10: Chamberlain Shaft – Kent and Chamberlain Street

This site will be the access point for the tunnel boring machine; a shaft is being constructed to launch the tunnelling operation for the North-South Tunnel to the Ottawa River.
Temporary site services (site trailer and electrical power) have been set up on site.
A crane was moved to the site for moving equipment and material into and out of the access shaft. Excavation of the soil from the access shaft is complete. A drill rig has been drilling into the bedrock and the controlled blasting has commenced to facilitate rock excavation.
Rock excavation activities (including controlled blasting) will not affect vehicle or pedestrian traffic. Notices were sent to nearby residents informing them up of blasting and excavation activities.
Secant Shaft Wall Ring Beam Concrete Works
Secant Shaft Wall Ring Beam Concrete Works


Excavation activities at Site 10 in close proximity to homes and businesses


Excavation activities at Site 10 in close proximity to homes and businesses

Mobility & You

Stay informed about capital infrastructure projects. Check out the City's interactive traffic map and traffic report or call 3-1-1 for updates about when and where construction is happening.

Contact Us

Visit us on the web at or email the project team at Note that the website is continuously updated with information on Open Houses, Public Information Sessions, and materials distributed at these events. Please continue to visit for updated information.

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