Merivale Transformer Station Modernization (31 Woodfield Drive, Nepean, Ontario)

Merivale Transformer Station (TS) is one of two critical stations that, together, supply approximately 60% of power to the City of Ottawa. This project will replace and modernize aging infrastructure, increase the capacity of the station, and improve the flow of power throughout the region. Upgrades made at Merivale TS will support additional power to flow to over 20 Hydro One and Hydro Ottawa connected stations. 


Part of this project is proposed to take place on lands owned by the National Capital Commission (NCC) and is subject to a federal land use, design, and real estate transaction approval under the National Capital Act


The NCC property is a greenfield parcel with unmarked trails used for public recreation. It is bounded by the Cityview-Crestview-Meadowlands community to the north and the Ottawa Central / Canadian National Railway corridor to the south. 


The work on NCC lands involves the construction of high-voltage power infrastructure, consisting of temporary 115 kilovolt ("kV") line structures, including wood pole and conductor installation. In total, eight (8) wood pole structures of various configurations and 420 metres of 3-phase transmission lines will be constructed on approximately 2.60 acres (10,522 sq. m.) of land.


Vegetation removal will be required to accommodate the appropriate clearances to the overhead 115kV lines. Based on the tree inventory conducted by Hydro One, most existing trees and shrubs are non-native or invasive. Approximately 235 trees bordering the railway corridor at the south end of the NCC property will need to be removed to allow for the safe operation and maintenance of the proposed transmission infrastructure. Where vegetation removals are scheduled to occur during bird nesting season (April 1 to August 31), the area subject to removal will be assessed and cleared by a qualified avian biologist. Vegetation removal will be conducted by Hydro One crews, who will use mechanical equipment such as a bulldozer, excavator, feller buncher and grinder. Construction of the transmission infrastructure will be performed using an excavator, dump truck, drum roller, boom truck and cranes. 


Construction is expected to begin in late April 2023 with a completion date of early November 2023. The construction area will be accessed from Merivale Road via 5-metre-wide access road within the NCC property. The access road will cover a total area of 0.85 acre (3,440 sq. m.). Temporary pads will be constructed for the installation of certain structures and will be removed once work is complete. Access to current open space, including sections of unmarked trails, will be reduced by the expanded infrastructure footprint and will be temporarily unavailable during construction. Construction work will abide by all municipal by-laws, including noise limits.


Mitigation measures, such as the minimization of the overall infrastructure footprint and tree clearing areas, are being included in the project's design. Per NCC guidelines, Hydro One will replant trees removed for this project, although not all replanting will take place on the subject property. 


Hydro One understands there may be temporary disruptions to the nearby community as a result of this project. Hydro One will continue to mitigate concerns where possible as we work to make Merivale TS more resilient, to ensure power is available for customers now and in the future.


Latest update

August 29, 2023 – The National Capital Commission issued its Notice of Determination and determined that the project is not likely to cause significant adverse environmental effects.


Key documents

Key documents
Document Number Document Title File Date
2 Notice of Determination - August 29, 2023
1 Notice of Intent to Make a Determination - Start of Public Comment Period - February 28, 2023

External links

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

  • Location

    • Merivale Transformer Station (Ontario)
  • Nature of Activity

    • Hydroelectric Energy
  • Assessment Status

  • Start Date

  • Proponent

    Hydro One
  • 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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