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.

In the news!

The Tunnel Boring Machine (TBM) is on its way and expected to arrive in Baltimore shortly! Follow the exciting updates of the journey and arrival of the TBM.
Tunnel Boring Machine
Tunnel Boring Machine

What is the TBM?

The TBM is a machine used to excavate tunnels with a circular cross section through a variety of soil and layers of sedimentary rock. It can bore through anything from hard rock to sand. 
It will be used to launch the tunneling operation for the North-South Tunnel at the Kent and Chamberlain site. When complete, a permanent access point to the underground tunnel will remain at this site.

The Journey

The TBM was loaded onto a ship to begin its long journey, destination Ottawa, Ontario!

It left Madrid, on March 24, 2017, and headed to a port in northern Spain were it was loaded onto a ship to cross the Atlantic Ocean.  Arriving in Baltimore, MD, its journey continues overland by trucks, transporting between 40 and 50 full-sized loads, across the Peace Bridge at Buffalo, NY.  From here, it will continue along Highways 401, 416 and 417 to the CSST North South Tunnel launch shaft near the Kent and Chamberlain site.  Once on site, the lengthy process of assembly will begin, much of which will be underground before the tunneling work begins.
Tunnel Boring Machine
Tunnel Boring Machine

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. 
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
 The map above shows the CSST sites, numbers 1 to 10. Sites 5, 6 and 10 are green, site 7 is grey and all other sites are red.

Changes to the CSST Route

What has changed?
  • Site 3C (Nicholas Street Shaft – Nicholas Street and Laurier Avenue) has been relocated to Wilbrod and Cumberland Streets and is now referred to as Site 3CR.
  • The East-West Tunnel route between Site 3CR and Site 3A has been adjusted as a result of the relocation of Site 3C.
What is the reason for the change?
  • To preserve NCC greenspace in the downtown core and to reduce geotechnical risk by moving the site further east to better ground conditions.
Below is the information regarding project sites that are currently active.

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

Construction activity began in New Edinburgh the week of March 20, 2017 to support the construction of CSST access shafts in Stanley Park (to launch the tunnelling operation for the East-West Tunnel) and at River Lane/Queen Victoria.
General site preparation continues. 
  • Tree and brush removal around Sites 5A and 5B is now complete in advance of the bird nesting season
  • Snow has been removed from the site
  • Chain link fencing has been installed
  • Sediment and erosion protection has been installed
  • Traffic flow signage from one-way traffic to two-way traffic is in effect on River Lane in advance of construction activities commencing at Site 5C.
As the construction site in the park develops, the contractor will be using the requisite interim truck route in and out of the park.  This interim route, which is a mix of the routes “N1” and “S1” presented at the CSST Open House (February 22, 2017), provides separate access and egress (exit) for construction vehicles. Specifically, the interim route in the figure below includes:
  • Route N1 functioning as access (enter): Trucks will enter New Edinburgh from Sussex Drive at Stanley Avenue, then access Stanley Park via Queen Victoria. 
  • Route S1 functioning as egress (exit): Trucks will exit the construction site along the multi-use pathway (MUP) then leave Stanley Park at Stanley Avenue near Dufferin Road. Trucks will then continue on Dufferin Road to Crichton Street and exit the community westbound at St. Patrick
Implementation of this final truck route will involve some temporary improvements where the MUP meets Stanley Avenue at Dufferin Road. The temporary improvements will provide improved safety to the public at that location.

An updated report, with the recommended preferred truck routes incorporating feedback from the open house, is available on the City’s website.
Interim trucking route
Interim trucking route
Fencing, tree and brush clearing in preparation of construction work

Fencing, tree and brush clearing in preparation of construction work

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

This site will be the exit point for the TBM traveling northward from Site 10 (Kent and Chamberlain). It will also be a permanent access point to the CSST once complete.
Tree clearing in the area is complete. The trees were removed early in the year so that the work occurs outside of the general nesting period for breeding birds.
Further to the tree removal, construction activities at this site are anticipated to begin in June 2017.
Tree and brush clearing activities in preparation for construction work

Tree and brush clearing activities in preparation for construction work

Site 10: Chamberlain Shaft – Kent and Chamberlain Street

This site will be the access point for the TBM; 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) remain on site.
Rock removal continues inside the access shaft.  Mining of the tail tunnel for the TBM will begin later this month and extend under Chamberlain Street.
Rock excavation activities and mining have not affected vehicle or pedestrian traffic. Notices were previously sent to nearby businesses and residents informing them of the excavation activities.
Post blast clean up inside access shaft using crane and excavator

Post blast clean up inside the access shaft using a crane and excavator

Looking south-east across the site over the access shaft


Looking south-east across the site over the access shaft

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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