Researchers from the University of Waterloo are the latest to recommend a standard across Canada for flood protection in communities at risk of overland flooding. The university says the nationwide standard should employ two dozen best practice. Such a standard would build protection and reduce water-related losses, including sewer back up protection.
One important part of the standard would be to prevent new homes being built in floodways or in the flood fringe. The only exception would be if flood-proofing measures are taking. Researchers published their findings in the report, titled Preventing Disaster Before It Strikes: Developing a Canadian Standard for Flood-Resilient Residential Communities.
The research was conducted in partnership between Intact Centre on Climate Adaptation (ICAA) and funded by the Standards Council of Canada (SCC).
Among the report’s recommendations are:
- “safety factors” should be used in new community design to account for potentially more frequent and sever rainfalls and storm water system failures;
- new development should not increase the risk of flooding for existing communities;
- new development should be designed to minimize the risk of basement flooding from groundwater infiltration; and
- heating, ventilation and air conditioning, fuel and electrical systems should be well-elevated from the basement floor or located above grade.
The standards and best practices would cover overland flooding, riverine flooding, storm and sanitary sewer surcharge, drainage system failures, and groundwater seepage. Standard measures would also help to reduce costs, both insurance and uninsured.
Some specific recommendations include the following:
- inlet control devices should be used to restrict the flow of storm water from the street into storm sewers;
- design of sanitary sewers should have a factor for “normal” infiltration or rainwater during typical rain events and a higher “safety factor” for infiltration and inflow during extreme rain events;
- roads and public spaces should be designed to convey excess runoff so that it does not flow through homeowner property;
- road design and lot grading should be such that the water on the road remains at least 30 cm below the lowest building openings;
- wastewater pumping stations should have back-up power to allow for a minimum of 48 hours of uninterrupted service and an overflow in case of catastrophic failure; and
- new development should not encroach on riparian buffers (land and natural vegetation adjacent to water bodies), and sufficient setbacks should be maintained along water bodies to reduce the risk of flooding due to stream movement and bank erosion.
“Ensuring that new communities are built under the direction of these practices is necessary to combat ever-worsening extreme weather that, if not addressed, will result in costly and unremitting flood damage,” states the report.
“These best practices constitute elements of residential community design and construction that, if implemented together, should achieve significant flood risk reduction,” the report adds.