Repercussions of an HV Transformer Oil Spill

In the case of an HV transformer oil spill in favourable conditions (soil contamination only, no snow cover), the following items must be considered and will incur costs:


  1. Power outage management
  2. Production losses due to power outage and/or during decontamination
  3. Realignment of the loads
  4. Insulating oil replacement
  5. Short-circuit tests with the new insulating oil
  6. Transformer isolation tests prior to restart
  7. Potential transformer failures from insulation breakdown due to oil loss

Costs Incurred

  1. Emergency protocols
  2. Intervention by environment inspectors
  3. Engineering/root cause analysis of the oil spill
  4. Mechanical and electrical work on the transformer
  5. Electrical work on buried conductors and grounding screens
  6. Mobilization of supervision staff
  7. Stoppage and/or relocation of other operations by the planning team
  8. Potential overtime to complete the job


  1. Initial emergency intervention with basic absorbent.
  2. Oil loss assessment.
  3. Report to the Ministry of the Environment.
  4. Inspection and requirements from Ministry inspectors.
  5. Purchase of special absorbents.
  6. Heavy machinery mobilization.
  7. Contaminated soil to decontamination firm.
  8. When there is a secondary concrete containment basin, due to the porosity, the inner walls must be sandblasted to remove all contamination (often requiring a crane and transformer shutdown)
  9. When there is a geotextile containment tarp, it must be inspected and replaced.
  10. Government fines and penalties
  11. Per-diem fees for external contracts.


  1. Jobsite equipment rentals.
  2. Vehicle rentals.
  3. Procurement of various materials.

Note 1:

When an HV transformer oil spill extends to a wet area or water table, the costs increase dramatically to insure no contaminants reach the surrounding waterways.

Note 2:

When an HV transformer oil spill occurs on frozen ground and/or snow cover, all access roads and areas surrounding the transformer, as well as access to potentially contaminated areas must be cleared. Also, whenever possible, heated shelters need to be installed above open water, boats are needed to inspect the waterways and to remove any oil patches with specialized products.