Trial Islands Lightstation Transformer Replacement

The existing BC Hydro transformer has reached the end of its serviceable life and requires replacement. The brick and cement structure containing the existing transformer, and the concrete pad it rests on, will be broken down and the rubble will be placed in containment bags in a designated laydown area, for subsequent removal by helicopter.  Machinery used in the project includes hand tools and portable drills. Waste materials will be contained within bulk bags in a laydown area adjacent to site and removed by helicopter (long line). New supplies will be brought in by helicopter (long line) and either placed in the laydown area (construction materials) or placed in situ (transformer). Once the old doghouse and pad are moved, the primary duct bank will be cut back to the first supporting concrete pier, removed and reformed for replacement.  Three 4 or 5 inch conduits will be routed to the transformer pad window location under the new precast concrete pad.  A new precast concrete pad will be placed bedding aggregate, within the footprint of the pad currently supporting the doghouse. A new replacement transformer will be set on the precast pad.  A drain rock frame will be placed around the new pad, extending 300mm from the footprint of the existing pad on all sides. A grounding counterpoise will be buried 300mm below the bedding aggregate; a portable drill will be used to bore four 3 m deep ground rod holes into the bedrock, about 90 cm from the concrete pad which will be fill with a ground rod connected to the grounding counterpoise together with natural conductive material.  In addition, four 1 m deep fence post holes will be drilled into the bedrock, about 1 m from the concrete pad and grouted into place.  A non-conductive removable vinyl fence will be attached to the posts to mitigate electrical step-and-touch hazards. Personnel, small hand tools, and light material may be brought to the Lightstation by boat and carried to the project work area by wheelbarrow, using existing paths.

Apart from drilling the fence-post holes into bedrock, no ground disturbance is expected with the project.

Helicopter slinging and boat support will be used to mobilize and demobilize equipment.


Latest update

August 31, 2023 – DFO has issued its Notice of Determination and determined that the project is not likely to cause significant adverse environmental effects.



Eliza Gray
Fisheries and Oceans Canada, Pacific Region
Eliza Gray, Project Engineer
25 Huron Street
Victoria, British Columbia V8V 4Z9
Telephone: 250-634-0574

  • Location

    • Trial Islands Lightstation (British Columbia)
  • Nature of Activity

    • Building and Property Development
    • Other, not otherwise specified
  • Assessment Status

  • Start Date

  • Proponent

    BC Hydro
  • Authorities

    • Fisheries and Oceans Canada
  • 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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