Canada’s long history of harnessing water for energy means that many of the country’s hydropower plants have been operating more than a century. When Ontario Power Generation needed to upgrade four 100-year-old generating stations on the Upper Mattagami River, the company relied on the expertise of Tetra Tech.

The project included demolition of the existing powerhouses, rehabilitation of the existing spillways, and construction of new powerhouses. When the project was completed, the total capacity of the stations was more than doubled—from 21 to 44 megawatts. The projects have gross heads ranging from 10 to 38 meters.

Tetra Tech developed concepts and specifications for all civil, mechanical, and electrical engineering work; reviewed final designs and submittals; and monitored the work during construction. Tetra Tech also successfully navigated the challenges of working on four sites concurrently, interacting with numerous stakeholders, and ensuring that the quality of both the on-site construction and off-site manufacturing met Ontario Power Generation’s quality standards. Tetra Tech completed the project under budget and ahead of schedule.

Services included:

  • Simultaneous implementation of four projects
  • Risk assessment and registry
  • Definition of permits and authorizations
  • Assistance for environmental assessment and First Nation's acceptance
  • Preliminary subsurface investigations
  • Document control
  • On-site construction monitoring and commissioning assistance
  • Off-site manufacturing quality assurance program
  • Preparation of technical information for interconnection on the Hydro One network following their specific process and compliance with Independent Electricity System Operator requirements