Outfall Control Gates
- Location Edmonton, Alberta
- Description
Outfall Control Gates – Project Outline
As part of EPCOR’s Flood Mitigation Outfall Control Gates program, extensive storm works were completed at both the Rossdale and E.L. Smith Water Treatment Plants to support new flow-control infrastructure designed to reduce backflow risk during extreme flood events. Our role focused on delivering the underground systems required to enable slide gate installation across multiple waste streams within live, operating treatment facilities.The scope spanned numerous work packages at Rossdale and E.L. Smith, work included deep excavations via Tunnel Plate liners and Slide rails systems, manhole construction, with additional temporary works and groundwater management to support construction in challenging subsurface conditions. Each location requires tailored excavation, shoring, tie-ins, and restoration-ready backfill solutions.Across both sites, the underground scope required sequencing dozens of individual work fronts, responding to unforeseen utility conflicts, and executing additional field-directed work such as sanitary repairs, coupling upgrades, deep dewatering, and localized realignments as conditions were uncovered. All work was coordinated around strict EPCOR operational constraints and shutdown windows, emphasizing constructability, safety, and schedule reliability in high-risk, high-consequence environments.This project demonstrates the ability to deliver complex underground infrastructure across multiple treatment facilities. The work required adapting to evolving scope and coordinating with active plant operations to support flood-mitigation systems, while maintaining close coordination with PCL Construction.Project Metrics at a Glance
Project Timeline
The project started back in November of 2023 and is still continuing this winter. Typically, work is completed during the winter months during the low-flow season.
Facilities
Two active water treatment plants (Rossdale and E.L. Smith).
Waste Streams
Multiple waste streams addressed, including WS4, WS5, WS6, WS7, sanitary, and combined systems.
Underground Work Packages
Numerous discrete underground scopes were delivered across phased construction and follow-on field work.
Manholes
Construction, replacement, rehabilitation, and tie-ins were completed across multiple locations and diameters.
Excavation Conditions
Deep excavations requiring engineered shoring and groundwater management.
Operational Constraints
Work sequenced around live plant operations and critical shutdown windows.
Adaptability
Additional underground works were completed in response to unforeseen conditions and operational requirements.
Delivery Model
Subcontracted underground civil works performed under PCL for EPCOR.
- Owner PCL subcontracted to EPCOR
