A Green Street is a road or street that incorporates green infrastructure, which includes natural and human-made elements such as trees, green walls, and low impact development (LID) stormwater infrastructure that provide ecological and hydrological functions and processes.
“Traditional” streets are designed to direct stormwater into storm sewer systems (gutters, drains, pipes) that discharge directly into surface waters, rivers, and streams. “Green” streets are designed to capture rainwater at its source, where it falls, providing water for plants and trees to grow and at the same time acting as a natural filter to clean the water before it makes its way into local waterways.
Toronto has approximately 5,600 km of streets – almost ¼ of Toronto’s total land area is covered by streets. Historically, streets have formed an impermeable paved layer on top of green space, which prevent natural hydrological cycles and increase the volumes of runoff entering our stormwater infrastructure.
When stormwater flows along streets and other hard surfaces it picks up dirt, oil, grease and other pollutants. Green Street projects provide a place for stormwater to soak into the ground providing water for plants and trees to grow. At the same time, plants and soil act as natural filters cleaning the water before it makes its way into local waterways.
A number of green infrastructure demonstration projects have been completed at various sites in the City and a number more are in planning stages.
Toronto’s Green Streets Technical Guidelines provide guidance, standards and selection tools for the planning, design, integration and maintenance of a range of green infrastructure options appropriate for the City’s street types and conditions.
The Guidelines are meant to be a tool for City staff, developers, and consultants with the key objectives of providing an understanding of sustainable stormwater planning and practices; informing the selection of appropriate green infrastructure options to be integrated as part of street retrofit/rehabilitation or new/reconstruction projects; and, ensuring that green street designs are attractive, functional and appropriate to their urban context.
Design Options for Tree Planting in Hard Surfaces illustrate how hard surface environments can be designed to achieve the higher soil volumes necessary for tree growth and survivability, storm water management, and facilitate utility subsurface access and maintenance activities.
Many of the Design Options include the installation of soil cells. The City is conducting a soil cell evaluation that will inform the development of a city standard soil cell specification. Until this is available, general specification 32 88 88 Soil Cells can be used to help identify performance criteria that should be incorporated when choosing a soil cell product for installation in the right-of-way.