Field evaluation of a Toronto green street technology

The Toronto’s Wet Weather Flow Management Guidelines (2006) recommended a number of stormwater practices for stormwater management in the City over the next 25 years. These practices include measures and devices at the source, along drainage systems, and at the downstream end of drainage systems. In order to implement these practices, technical specifications of these practices must be established.   Part of the technical specifications should be based on field testing of the practices in terms of suitability, performance, construction, and maintenance requirements.  

The project focuses on the field testing of a new and untested stormwater low impact development (LID) practice using Soil Cells (SC). The concept is to divert road runoff collected at catch basins into soil cells under the sidewalk and parking lay-by.  It is theorized the redirected stormwater will be treated via filtration as it seeps through the porous fill/soil within the soil cells prior to flowing back into the storm sewer.

Two SC were constructed in October 2008.  This presentation reports selected field performance data on the functioning of soil cells along a section of The Queensway in Etobicoke. Performance is defined by the concentration changes/reductions (detailed in this report) and mass loading reductions of measured parameters/contaminants in the stormwater runoff after passing through the SC.  Refrigerated automatic wastewater samplers and flow meters were installed at the inlet and outlet of the SC.   A rain gauge was set up about 75 m from the inlet catchbasin of the operational eastern soil cell.  Soil moisture and water level sensors were installed within the SC to investigate the hydraulic conditions of the system during a storm event. More than 25 rainfall events were monitored in 2014 and 2015.