Building a corridor that connects communities and holds its standard
The Finch West Light Rail Transit (LRT) project adds 11 kilometers of new transit infrastructure with 18 stops, significantly improving how residents move across the corridor. Metrolinx owns the project and Mosaic Transit Group (Mosaic) delivers it through a public-private partnership (P3). The intended outcome goes beyond new track and stations: improved connections, reduced travel times, lower transportation emissions over time and an economic boost tied to better access.
Delivering that long-term community value requires disciplined execution during construction. The project footprint stretched across a linear corridor with multiple active work fronts, shifting site conditions and sensitive areas. Teams needed clear direction that matched a dynamic design-build pace while meeting stringent environmental obligations day after day.
Onterris worked alongside the Mosaic team from pre-construction into active construction, staying close to the project’s commitments so crews could act quickly without losing compliance or documentation quality. Following project substantial completion in November 2025, our team continues to provide environmental leadership during operation and maintenance.
Creating a single point of environmental direction at construction speed
On large transit programs, environmental responsibilities often span multiple disciplines, contractors and work packages. Maintaining consistency across project locations and keeping decisions moving efficiently requires clear coordination. To support that alignment, Onterris served as Environmental Director for the Finch West LRT project, providing leadership for Mosaic environmental and sustainability programs.
The role included acting as lead authorizing signatory of plans, reports, and documentation tied to the project’s Environmental Obligations, plus ongoing coordination to keep environmental requirements visible in daily planning. With one consistent review lens, the project team could align expectations across subcontractors and work fronts, support consistent field practices and document decisions in a way that meets owner requirements.
Turning risk areas into field-ready plans crews can execute
Construction planning required early clarity on potential contamination and ground conditions. Onterris led contaminated soils investigations to support construction readiness, coordinating environmental and geotechnical sampling campaigns to delineate areas of concern. The program included management of a drilling and sampling effort with hundreds of boreholes distributed across the project area.
That work supported practical decisions about sequencing, excavation methods and material handling so teams could plan confidently before and during mobilization. When conditions shifted, the team stayed engaged to keep field direction and documentation aligned.
In parallel, erosion and sediment control needed to remain consistent and defensible across sensitive lands. Onterris prepared comprehensive Erosion and Sediment Control Plans for multiple sites, including areas under the jurisdiction of the Ministry of Transportation Ontario and the Toronto and Region Conservation Authority. The plans translated requirements into constructible controls, clear installation intent and inspection expectations matched to active works.
Ecology support added another layer of readiness. Wildlife ecology teams completed numerous avian nest sweeps at multiple locations along the corridor, including woodlots and areas under bridges. This reduced uncertainty during seasonal windows and kept disturbance activities aligned with environmental requirements.
Design-build delivery moves fast, so we kept environmental direction just as fast and clear. Staying close to field teams, we focused on practical controls and decision-ready documentation that crews could execute safely and consistently.
Outcome that protected delivery and long-term value
By embedding leadership and maintaining multidisciplinary coverage, Onterris provided responsive support for a dynamic transit construction program. The approach kept obligations visible in daily decisions, strengthened consistency across multiple sites and supported compliance while enabling efficient project delivery.
The project reached substantial completion in Q4 2025, advancing a corridor intended to connect communities, improve transportation efficiency and support reduced emissions and quality of life over the generations that will use it.
Where the project stands and what it models
Onterris continues to support Mosaic following substantial completion, sustaining the documentation discipline and environmental program clarity that design-build transit projects require. The approach offers a repeatable model for transit P3 teams: combine embedded environmental leadership with specialists who remain closely tied to field reality, ensuring project delivery protects both schedule reliability and the public value the infrastructure is intended to unlock.
