Rehabilitation of the Colonel By Drive Wall

The National Capital Commission (NCC) is proposing to repair and restore sections of the Colonel By Drive Wall that have been damaged over time due to salt and snow load. This retaining wall is located on the east side of Colonel By Drive, between Clegg Street and Grosvenor Avenue. The wall has a total length of 920m, however, approximately 400m of wall will be affected by this project. It is situated across the street from the multi-use pathway that borders the Rideau Canal, a UNESCO World Heritage Site. The retaining wall is designed to support the ground further east, which is at a higher elevation with respect to Colonel By Drive, including a vegetated landscape strip followed by Echo Street.  

The project is set to be implemented in September of 2020 and is anticipated to be completed by December 2020.

In order to promote resiliency following reconstruction, a new design was chosen for the portions of the retaining wall that will be replaced. The materials, appearance and engineering design for the retaining wall was completed by NCC Design & Construction staff.

The NCC has selected amour stone blocks as the preferred construction material. These blocks are extremely durable, and their appearance will help to preserve the aesthetic uniformity of the wall.

Although armour stone does not convey the same heritage characteristics as the current stone and mortar style wall, it was chosen as a preferred material as it resilient, has a natural appearance and will help minimize the impacts to the rustic heritage characteristic, when compared to other more modern options. Additionally, the NCC design team has committed to undertaking studies into the use of lime-based mortars to develop approaches to future for wall reconstruction. It should be noted that the use of armour stone at this location will not set a precedent for repairing other sections of stone wall along Colonel By Drive and the Rideau Canal.

The reconstruction will consist of simply stacking these large heavy blocks one on top of the other. This will result in a wall that is more resistant to both weathering and erosion than the current mortar and stone wall that is in place.

The construction plan includes the following components:

  • Installation of necessary tree protection measures prior to construction;
  • Limited tree and shrub removal within excavation zone;
  • Implementation of traffic management measures during construction;
  • Removal of approximately 400 m of the existing wall system from the south side of stairway near Mt. Pleasant Avenue to Avenue Road. The removal will include sidewalk slabs, light posts, electrical cables, etc;
  • Excavation of soil behind the retaining wall and installation of slope stability measures;
  • Construction of approximately 400 meters of new armour stone retaining wall;
  • Installation of effective drainage system behind the new retaining wall;
  • Deposition of new non-frost susceptible fill material behind the wall;
  • Reinstallation of related items, such as sidewalk slabs, light posts, electrical cables, etc; and
  • Implementation of revegetation and landscape plan.

As the project will affect motorists along Colonel By Drive, the NCC will inform the public and stakeholders of any anticipated traffic delays or planned detours. 


Latest update

July 24, 2020 - The assessment decision statement has been issued to the proponent.


Key documents


Environmental Assessment
National Capital Commission
40 Elgin Street
Ottawa, Ontario K1P 5A8

  • Location

    • Ottawa - Rideau Canal (Ontario)
  • Nature of Activity

    • Maintenance activities (fences, walls)
  • Assessment Status

  • Start Date

  • Proponent

    National Capital Commission
  • Authorities

    • National Capital Commission
  • Assessment Type

    Project on federal lands
  • Reference Number


This map is for illustrative purposes. The markers represent the approximate locations based on available data. More than one marker may be identified for a given assessment.

Nearby assessments

...within 200 kilometres
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