Assimilative Capacity Study

The Mid-Halton waste water treatment plant sought to expand its capacity from 75 to 125 MLD. An Assimilative Capacity Study was completed as part of the Environmental Assessment to determine the impacts of the additional effluent loading.

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Halton Region
Oakville, Ontario
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Oakville, Ontario

Project Highlights

Numerical modeling optimized the outfall location while verifying that the receiving water would continue to meet the Provincial Water Quality Objectives with the increased effluent loading.


  • Near-field modeling assessed water quality impacts
  • 3D hydrodynamic and advection dispersion model assessed water quality impacts in the far-field.
  • Optimization of outfall and diffuser location balanced costs of extending the outfall with environmental benefits.

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Project Challenges

  • Ensure all regulatory agencies are informed to avoid project delays.
  • Assess overlapping effluent plumes from existing WWTPs.
  • Determine the impact on several drinking water intakes located within kilometers of the outfall.

Baird Solutions

  • Meetings were held with the Ministry of Environment early in the project and regular communication found a solution that worked for all.
  • Results from nearby WWTPs were incorporated into far-field model and assessed at local points of interest.
  • Impacts of the effluent flow were evaluated with the far-field model to ensure water quality would not be compromised.

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