AECOM Selected for Ontario Pumped Storage Support

Estimated reading time: 5 minutes · Last updated: 11 September 2026

AECOM has been engaged by Worley to provide engineering and planning support for the proposed Ontario Pumped Storage Project near Meaford, Ontario. The development is described as a long-duration storage facility with roughly 1,000 MW of generating capacity and 10,600 MWh of energy storage. AECOM's contract covers underground infrastructure, hydraulic systems and work to improve constructability and operability while the scheme moves through detailed engineering. The engagement is an early-phase, planning-focused role intended to produce cost and schedule estimates, risk assessments and technical inputs ahead of any investment decision.

What AECOM will deliver for the Meaford scheme

AECOM's engagement covers a technical and programme role during the project's engineering phase. The firm will work on underground infrastructure and hydraulic systems, and assess how those elements can be built and operated over the life of the facility. Those tasks typically include tunnelling and cavern design review, penstock and surge shaft engineering input, and constructability modelling to identify sequencing and access constraints.

Beyond technical layouts, AECOM will assemble cost and schedule inputs and run project-level risk assessments. That work is intended to support the project owner and delivery team in refining budget ranges, phasing options and procurement strategies before a binding construction contract is awarded. The project filing lists those boundaries in scope — underground works, hydraulic systems, constructability and operability, plus cost, schedule and risk — but the filing does not disclose a contract value or delivery dates.

How large the proposal is and what that implies

The project is described as providing about 1,000 MW of generation capacity together with 10,600 MWh of energy storage. Those two figures imply the facility is sized for long-duration dispatch: dividing stored energy by power gives an approximate full-power discharge duration of about 10.6 hours. That duration positions the scheme to shift large volumes of energy across daily demand cycles and to provide multi-hour system support rather than short-term frequency services.

A 1,000 MW plant with 10,600 MWh of storage will require substantial civil works, including large upper and lower reservoirs, tunnels and underground machine halls, and extensive hydraulic control hardware. The engineering phase AECOM will support is the stage where those requirements are translated into buildable contracts, where risk related to geology, groundwater and excavation methods is quantified, and where schedule assumptions for major packages are checked against on-site constraints.

Why pumped storage is being advanced in Ontario

Pumped storage stores electricity by moving water between elevation-separated reservoirs, charging when supply exceeds demand and discharging through turbines when demand rises. That model provides long-duration capacity and large-scale flexibility, which the project's proponents argue is needed as Ontario integrates more variable generation and faces higher peak loads. Proponents present the development as a response to increasing electricity demand and the grid's need for extended-duration resources.

For system planners, a pumped storage installation sized like this can replace or defer other forms of long-duration capacity and reduce reliance on fossil-fuel peakers at times of extended demand. The engineering and planning outputs from AECOM will therefore feed into broader resource-adequacy and interconnection assessments undertaken by the operator and the regional planning authorities, although the provided text does not detail those regulatory or market integration steps.

Engineering challenges, procurement and the path to a decision

Large pumped storage projects concentrate risk in site geology, underground construction methods and hydraulic performance. The early engineering work AECOM will perform aims to reduce uncertainty in those areas by defining excavation sequences, lining systems and water-handling measures. That information is critical for setting realistic bid packages for tunnel contractors and for sizing contingency allowances in cost estimates.

Procurement choices made after the engineering phase — single EPC versus multiple specialist contracts, risk allocation for ground conditions, and contractor sequencing — will materially affect schedule and budget. The engagement described is preparation for those procurement decisions: producing the technical deliverables and cost models that owners and financiers use to judge whether to proceed to final investment. The source material does not provide a capital cost estimate, a planned construction start date or a named project owner beyond the Worley-led team and the involvement of AECOM.

Positive case and headwinds for the project

The bottom line

AECOM's engagement signals that the Meaford pumped storage concept is moving from conceptual study toward detailed engineering and commercial preparation. The disclosed figures — 1,000 MW and 10,600 MWh — place the scheme among larger long-duration storage proposals and make underground and hydraulic design, plus constructability, the central engineering priorities. The work AECOM will perform is aimed at reducing uncertainty ahead of procurement and financing, but the project filing provides no capital-cost estimate, financing plan or schedule. Those items will determine whether the project advances to construction.

What to watch

• Watch for the project's investment decision; no date has been set.
• Watch for the release of the next-phase engineering deliverables that set a cost range and procurement approach; no date has been set.
• Watch for appointment of major civil or tunnel contractors; no date has been set.