digester gas cogeneration facility
Role
General Contractor
Client
City of Waterloo
Location
Galt, Kitchener, and Waterloo, Ontario
Timeline
March 2018 - April 2020
W.A. Stephenson Mechanical Contractors Ltd. was proud to serve as the General Contractor for the simultaneous construction of three new cogeneration facilities at the Region of Waterloo’s Galt, Kitchener, and Waterloo Wastewater Treatment Plants. This coordinated effort enhanced energy efficiency and biogas utilization across all sites, aligning with the Region’s long-term sustainability and infrastructure modernization goals.
Each facility included the installation of:
A reciprocating engine generator (600–800 kW capacity)
Gas conditioning systems
Heat recovery systems with integrated heat exchangers
Upgrades to electrical and control systems
The cogeneration systems capture biogas produced from wastewater treatment and convert it into usable electricity and heat, significantly reducing flaring and energy consumption at each plant. All systems were containerized for efficiency and delivered on-site with minimal disruption to ongoing operations.
Despite varied site conditions, construction across all three locations was completed on a synchronized schedule, demonstrating our ability to manage complex, multi-site infrastructure projects effectively. The result is a more sustainable, energy-resilient wastewater network for the Region of Waterloo.
r.c. harris wwtp
Role
Mechanical SubContractor
Client
City of Toronto
Location
Toronto, Ontario
Completion Date
June 2020
W.A. Stephenson Mechanical Contractors Ltd. served as the mechanical subcontractor for the critical rehabilitation of the historic R.C. Harris Water Treatment Plant Pumping Station. As one of Toronto’s most iconic and operationally essential water treatment facilities, this project required expert coordination, strict heritage protection, and uninterrupted plant functionality throughout.
Lead Abatement & Surface Restoration:
Environmental containment and abrasive blasting of lead-based coatings from aging mechanical systems, followed by surface preparation, priming, and industrial coating application.Mechanical Fastener Replacement:
Full replacement of legacy mechanical fasteners with new stainless-steel components to enhance system durability.Flange Recommissioning:
Pressure testing and sealing of all flange connections post-reassembly to ensure leak-free operation.Heritage Component Protection:
Careful isolation and safeguarding of heritage architectural features and equipment, including mosaic tile floors and vintage mechanical assets.Additional Process/Mechanical Work Included:
Installation of a new backwash tee and couplings with gaskets in the Filter Gallery
Removal and reinstallation of 110 AWI laterals in accordance with AWI instructions and procedures
Cleaning of AWI laterals and associated media clean-up during operations
Worksite Coordination:
All activities were carefully staged to maintain continuous plant operations, ensure personnel access, and meet all City safety and environmental compliance requirements.
OP Trust Wwtp
Role
Mechanical SubContractor
Client
City of Toronto
Location
Toronto, Ontario
Completion Date
In Progress
W.A. Stephenson Mechanical Contractors Ltd. was engaged as the principal mechanical subcontractor for the major rehabilitation of the Richview Pumping Station, Valve House, and Reservoir, one of Toronto’s critical water infrastructure assets. This multi-disciplinary project included significant upgrades to process, electrical, civil, and architectural systems, with special focus on maintaining uninterrupted operations throughout the construction period.
W.A. Stephenson was responsible for the supply, installation, and commissioning of all mechanical process and HVAC systems across the pumping station, valve chambers, and reservoir areas. Specific responsibilities included:
Process Piping and Valves: Replacement and integration of new process piping systems and control valves to improve water conveyance and system reliability.
HVAC Systems: Comprehensive refurbishment of ventilation, heating, and cooling systems for the Pumping Station and Standby Power Generation Room to support building performance and safety.
Mechanical Equipment Installation: Installation of pumps, appurtenances, and auxiliary systems supporting both the upgraded process and new standby power infrastructure.
Support During Phased Construction: Active participation in staged construction efforts, ensuring mechanical services supported continued facility operation and met city access and safety requirements.
Richview Pumping Station
Role
Mechanical SubContractor
Client
City of Toronto
Location
Toronto, Ontario
Completion Date
In Progress
W.A. Stephenson Mechanical Contractors Ltd. was engaged as the principal mechanical subcontractor for the major rehabilitation of the Richview Pumping Station, Valve House, and Reservoir, one of Toronto’s critical water infrastructure assets. This multi-disciplinary project included significant upgrades to process, electrical, civil, and architectural systems, with special focus on maintaining uninterrupted operations throughout the construction period.
W.A. Stephenson was responsible for the supply, installation, and commissioning of all mechanical process and HVAC systems across the pumping station, valve chambers, and reservoir areas. Specific responsibilities included:
Process Piping and Valves: Replacement and integration of new process piping systems and control valves to improve water conveyance and system reliability.
HVAC Systems: Comprehensive refurbishment of ventilation, heating, and cooling systems for the Pumping Station and Standby Power Generation Room to support building performance and safety.
Mechanical Equipment Installation: Installation of pumps, appurtenances, and auxiliary systems supporting both the upgraded process and new standby power infrastructure.
Support During Phased Construction: Active participation in staged construction efforts, ensuring mechanical services supported continued facility operation and met city access and safety requirements.
highland creek wwtp
Role
Mechanical Contractor
Client
City of Toronto
Location
Scarborough, Ontario
Completion Date
March 2011
W.A. Stephenson Mechanical Contractors Ltd. served as the mechanical contractor for the Phase 1 upgrades at the Highland Creek Wastewater Treatment Plant. This project focused on modernizing critical aeration infrastructure while maintaining uninterrupted plant operations—a testament to careful planning, precise execution, and close collaboration with facility staff.
Fine Bubble Aeration System Retrofit: Full replacement of the aeration system in two existing process tanks, including the installation of new stainless steel aeration headers to improve system efficiency and oxygen transfer performance.
Effluent Pump Upgrades: Supply and installation of new effluent pumps and related mechanical connections.
Process Piping & Utility Services: Installation of new plumbing, heating, and gas piping systems to support upgraded process operations.
Tank Cleaning & Surface Preparation: Power washing and cleaning of the interior tank surfaces to prepare for mechanical retrofits and phased tie-ins.
Staged Commissioning: Phased execution allowed for one tank to remain operational at all times. This required detailed coordination with City of Toronto staff for isolations, shutdowns, and live tie-in work.