Project Update - Combined Sewage Storage Tunnel (CSST) - September 2017

Ottawa River

Building a healthy and resilient future for the Ottawa River

This $232.3 million construction project is a key part of the Ottawa River Action Plan (ORAP), which is aimed at enhancing the health of the Ottawa River and protecting our water environment for future generations. A healthy water environment provides safe, abundant drinking water; supports agriculture, recreation and tourism; lessens the impact of flood events; and helps sustain fish and wildlife.
Project Facts

Construction Activity Progress

This map identifies construction sites for the CSST project within the City of Ottawa.
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 East-West tunnel will run through the downtown core from LeBreton Flats to New Edinburgh, and the North-South tunnel will run below Kent Street from Chamberlain Avenue to behind the Supreme Court.

Construction has already started at several of the sites indicated in orange.  Site 7, identified with the grey dot, was eliminated during the design phase of the project.
Please continue to visit for updated information and construction site activity.

North South Tunnel (NST)

Tunneling of the North-South Tunnel (NST) from Kent and Chamberlain Streets to the Ottawa River (Site 10 to Site 6) will begin this fall.

Site 10: Chamberlain Shaft (Kent and Chamberlain Streets)

Site 10 will be the access point for the tunneling operation for the North-South Tunnel to the Ottawa River; a 13-metre-diameter shaft is being constructed to launch the tunnel boring machine (TBM).

The TBM has been specifically designed to cut through solid rock at the pace of roughly 20 to 25 meters per day.

Site 10 construction activities of interest:
  • Pre-assembly of the TBM continues in preparation for installation at the access shaft
  • Line drilling, rock-splitting and excavation for the TBM’s tail and starter tunnels (needed to assemble the TBM) continue
  • Continued foundation installation for the gantry crane – a multipurpose crane adjacent to the access shaft
  • Grout plant silos have been installed
Grout plant silos used for pumping materials during tunneling
Grout plant silos used for pumping materials during tunneling
Site 10A view overlooking the access shaft
Site 10A view overlooking the access shaft

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

Work is expected to commence mid-October 2017.

Site 5: East-West Tunnel Outlet and Rideau River Collector Diversion (New Edinburgh)

Construction continues in New Edinburgh’s Stanley Park.

Site 5 construction activities of interest:
  • Relocation of utility poles and associated wires at Site 5C, at the intersection of Queen Victoria Street and River Lane
  • The erection of structural steel at the Odour Control Facility (OCF) is complete; roofing and masonry have now begun
  • Rock excavation within the shaft at 5A and 5B is well underway
  • Continual monitoring of vibration and noise levels
  • Noise barrier installed at Site 5B at Queen Victoria access to the park
Installation of roofing at Odour Control Facility (OCF)
Installation of roofing at Odour Control Facility (OCF)

Safety First!

Work to improve traffic and pedestrian safety along Stanley Avenue, in the vicinity of the CSST project egress, will soon be complete and features new sidewalks, a pedestrian crossover, signage, and accessibility features. The City would like to thank community members for their efforts in helping to make this work possible.

The City looks forward to continuing to collaborate with residents, businesses, and community associations through the CSST project.
New sidewalk, PXO (pedestrian crossover), and road surface along Stanley Ave
New sidewalk, PXO (pedestrian crossover), and road surface along Stanley Avenue

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

The CSST Project Team is committed to sharing information that may help affected residents and businesses plan around construction in their neighbourhoods.

For more information, please contact us using any of the following methods:

The CSST dedicated phone number is 613-580-2424 ext 2CSST (22778) and does not replace 3-1-1.
Visit us on the web at or email the project team at
Banner with ORAP logo and City of Ottawa logo with wording that sayd, Supporting an environmentally sustainable Ottawa.
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