Graham is pleased to announce that the EPCOR Primary Effluent (PE) Channel Upgrade in Edmonton, Alberta has reached Substantial Completion.
Since the 1950s, this wastewater treatment facility has played a vital role in removing solids and targeting hazardous dissolved compounds. The PE Channels are central to the plant’s process, feeding the bioreactors that require a continuous and reliable effluent supply. Graham’s scope focused on the rehabilitation of these channels, delivered in carefully sequenced phases to minimize operational impacts and supported by an Integrated Project Delivery (IPD) model.
Key Project Execution Phases
Stage 1 – Bypass Chamber
Work began with the bypass chamber, where sections of the chamber roof slab and concrete walls were removed to improve constructability. Four temporary flumes were installed inside the existing channels, allowing rehabilitation work to proceed while maintaining continuous effluent flow. Steel supports and ten permanent stop logs were added to isolate work areas, and all penetrations and channel walls were sealed. A cross-connection was constructed between Plant 1 and the North PE Channel, and extensive concrete rehabilitation and waterproofing were completed.
Stage 2 – “Hockey Stick” Channel
The second phase involved constructing a new “hockey stick” channel to connect the North and South PE Channels to the existing bioreactors, supported by new connection chambers. To allow isolation and flow control, three permanent stop logs were installed upstream in both channels, along with one additional stop log inside the new structure.
Stage 3 – Bioreactor 3–4 Connection
The final stage included demolishing and replacing the existing feed to Bioreactors 4 and 5 with a new permanent cross-connection. Additional concrete rehabilitation and waterproofing were completed within both the North and South PE Channels, particularly between the newly installed stop logs around the equalization chamber.
Innovations and Key Successes
A major contributor to project success was the use of the IPD model. Through Big Room sessions and pull planning, Graham, EPCOR, and project partners were able to respond quickly to field unknowns while maintaining schedule milestones and day-to-day plant operations—including traffic control, effluent flow, rain events, and site logistics. When unexpected sludge buildup of up to six feet threatened progress, the IPD model enabled rapid communication and collaborative problem-solving, minimizing delays and cost impacts.
To maintain uninterrupted flow to the bioreactors during channel rehabilitation, Graham developed a custom temporary flume system that replaced the originally proposed continuous bypass. This approach significantly reduced both cost and schedule impacts while validating the benefits of the IPD process.
These temporary flumes, engineered to handle peak flows of 420 megalitres per day, made it possible to install 14 stop log frames without disrupting plant operations. Each flume featured double steel plates with inflatable rubber seals and independent compressor systems for redundancy and safety. Their flexible design accommodated unexpected dimensional variances in the aging concrete structure, proving essential in adapting to onsite conditions.
Worker safety was maintained through comprehensive controls addressing H₂S exposure and confined-space hazards. Measures included engineered flumes with davit arms and ladders, thorough decontamination procedures, continuous gas monitoring, and negative-air systems. Over 16 months of work near open channels, the project maintained a zero major-injury record.
Construction began in June 2023 and is expected to reach final completion by the end of 2025, with project closeout anticipated in late 2026.
This milestone reflects the shared commitment of Graham and EPCOR to innovation, collaboration, and safety in delivering essential upgrades that support sustainable wastewater treatment for the Edmonton region.
