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8. Preserving the Greenbelt by Practicing the 3Rs

We do not need to destroy more of the Greenbelt to ensure the GTA’s infrastructure is maintained and grows. The simple solution, as outlined by the Ontario Greenbelt Alliance[1] is to take something we practice every day at home – the 3Rs (reduce, reuse and recycle) and apply it to aggregate use in our cities.

Reduce: Most importantly, we need to reduce our reliance on “virgin” aggregate. That doesn’t mean we stop building: rather the demand for virgin aggregate extraction can be reduced by changing building codes and provincial standards. For example, neighbourhood road designs can be altered to conform to the 6.5 metre road width found in older municipal developments in Ontario rather than the 8.5 metre road width of today’s sprawling local streets.[2]

Reuse: More often than not, when we renew our existing urban infrastructure, we create the raw materials we need for new construction. New materials, however, are not always necessary. Depending on road conditions and seasonal temperatures, nearly 100% of the surface asphalt can be reused. The Ministry of Transportation (MTO) uses a variety of reclamation methods that reuse the asphalt surface of our major highways.[3] This lessens the demand for not only virgin aggregate, but also the crude petroleum used to create asphalt.

Recycle: Crushed concrete and aggregates can be recycled as fill in a variety of construction projects. Ontario standards currently allow for such uses of recycled debris but there is no monitoring and no requirement that recycled aggregate be used first. This and more can and is being done in other jurisdictions. For example, of the 281 million tonnes of aggregates used in the UK, 67 million tonnes – about 24% – is recycled aggregate.[4] In contrast, the Ontario Ministry of Natural Resources claims up to about 7.2% of Ontario’s annual aggregate use is made up of recycled aggregate.[5]

A positive GTA example of recycling was the work done by the St. Lawrence Cement Group during the demolition of parts of the Lester B. Pearson International Airport. 450,000 tons of concrete rubble was crushed and recycled for use in road base materials.[6]


[1] Ontario Greenbelt Alliance. Green Gravel: Priorities for Aggregate Reform in Ontario. http://greenbeltalliance.ca/reports/Green Gravel Priorities FINAL.pdf

[2] Environmental Commissioner of Ontario. 2002-2003 Annual Report. Toronto: Environmental Commissioner of Ontario, 2003, pg 34. “The ECO speculates that a review of the design standards for urban streets and new subdivisions could serve a dual purpose, both conserving aggregate and reducing urban sprawl.”

[3] Ontario Ministry of Transportation. Southern Highways Program 2008 – 2012. http://www.mto.gov.on.ca/english/pubs/highway-construction/southern-highway-2008/index.shtml, 2007.

[4] Quarry Products Association, 2006. A variety of measures have been put in place by the UK government to encourage the use of recycled aggregate including not allowing aggregate construction wastes in landfills and charging a levy of about $4.00 CDN per tonne on primary aggregate extraction.

[5] Messerschmidt, B and M.MacKay. Mineral Aggregate Recycling and Reuse Study 2008 Pavement Rehabilitation and Preservation Workshop presentation, 2008.

[6] St. Lawrence Cement Group. Building Value Responsibly Sustainable Development Report February 2006. www.holcim.com/holcimweb/gc/CA/uploads/SLC SD Report February 2006 FINAL.pdf