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Standard would help enhance flood resilience of new communities: report

September 26, 2017   by Angela Stelmakowich

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Research out of the University of Waterloo recommends a Canadian standard for new flood-resilient residential communities, one that employs almost two dozen best practices, be developed to bolster protection and reduce water-related losses.

Requiring that new homes not be built in floodways or in the flood fringe unless flood-proofing addresses related risks is just one of the best practices detailed in the report, Preventing Disaster Before It Strikes: Developing a Canadian Standard for Flood-Resilient Residential Communities, issued Tuesday.

Funded by the Standards Council of Canada (SCC) and conducted by the Intact Centre on Climate Adaptation (ICCA), the research by ICCA’s Natalia Moudrak and Blair Feltmate identifies 20 best practices aimed at designing and building more flood-resilient new residential communities.

Beyond building location, though, the report’s “Design for Resilience” recommendations also cite the need for the following:

  • “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.

Developed following consultation with municipal storm water management experts, engineering consultants, developers, insurers and homebuilders, the best practices take into consideration riverine flooding, overland flooding, storm and sanitary sewer surcharge, drainage system failures and groundwater seepage.

The measures seek to cap losses – both insured and uninsured – resulting from storm events Canada-wide.

Related: Insured damages exceeds $124 million from Windsor August floods: CatIQ, IBC

These events carry financial and emotional tolls amounting to millions of dollars in property damage and untold stress to homeowners. In all, 1.7 million Canadian households are at risk of riverine and overland flooding, ICCA reports in a statement, citing figures released by Insurance Bureau of Canada.

Water-related losses are creating several concerns that must be addressed, the report notes, including the associated financial and mental health stress; insurable risk that could spur higher premiums or insurance availability issues; the possibility of mortgage defaults for homeowners with limited coverage who are unable to pay for flood damage; legal risks flowing from lawsuits for homeowners, developers, municipalities, provinces and insurers; and the possible negative impact on municipal credit ratings.

The report also offers recommendations on storm sewer design, sanitary sewer design, street design, wastewater pumping station design and preservation of natural features. Some specific recommendations in those categories 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.

Related: Alberta government addressing flood resilience in Calgary

SCC, as a next step, will “commit additional funding toward the development of a national standard on how to build flood-resilient communities, based on the best practices,” notes the joint statement.

“This important work provides the foundation for developing a standardization solution that meets stakeholder needs and helps protect one of the most valuable assets of Canadians,” SCC CEO John Walter adds in the statement.

A standard would also promote greater consistency. Communities across Canada use different approaches to address flood management, the report notes. Differences are only enhanced by the fact that “provinces and territories adopted different target ‘levels of service’ or ‘levels of risks’ to guide flood management,” it adds.

“The notable differences in these definitions and in regulatory flood standards through Canada can add to uncertainty about acceptable flood risks in the country and can hinder national efforts to streamline flood management in Canada,” the report states.

Related: Maintaining wetlands could slash riverine flooding-related damage, local pilot project has national applicability: study

“A national standard for flood-resilient residential community design can help local governments, developers, homebuilders, design professionals and contractors to better understand the minimum expected design and construction requirements for building new residential subdivisions that are less prone to flooding,” it emphasizes.

The report notes that benefits of such an approach include the following:

  • reduced liability – applying agreed-upon industry standards could help demonstrate an applicable standard of care was met and proper due diligence was exercised in the design, construction and approval of new residential communities;
  • improved local co-ordination and planning – having a standard can offer a more predictable playing field for developers, design professional and contractors;
  • clarity for developers – the greater the certainty that new homes are not permitted in the flood-prone areas, the lower the incentive for developers to acquire this land for new residential community development;
  • improved construction quality – enforcement of the standard can aid in maintaining quality of life and property values;
  • improvement public awareness – enforcement of the standard can help protect homebuyers from purchasing substandard housing; and
  • improved inspections – building inspectors familiar with flood-mitigation provisions are more likely to identify flawed construction.
Blair Feltmate, head of the Intact Centre on Climate Adaptation

Blair Feltmate, head of the Intact Centre on Climate Adaptation

“With the larger storms that we are seeing today, and the bigger ones that are coming, those who purchase homes in communities built in line with these recommendations will also be buying some peace of mind every time it rains,” Blair Feltmate (pictured left), a professor in the University of Waterloo’s Faculty of Environment and head of ICCA, says in the statement.

ICCA is seeking input by Oct. 31 on the effectiveness of the best practices to reduce flood risk and their practicality for implementation. The centre also welcomes suggestions for additional best practices from municipalities, building practitioners and other interested parties on how to bolster the flood resiliency of new communities.

Don Forgeron, president and CEO of Insurance Bureau of Canada

Don Forgeron, president and CEO of Insurance Bureau of Canada

“On behalf of Canada’s property and casualty insurers, IBC welcomes this report and we support the hard work led by the ICCA and the SCC,” Don Forgeron (pictured right), president and CEO of IBC, tells Canadian Underwriter.

“We need our communities across Canada to be more resilient when faced with flooding. Setting standards for new community construction is a good first step. Governments across Canada, and organizations like IBC, the ICCA and the SCC, need to work together and lead a ‘whole of society’ approach to reduce risks for consumers in a thoughtful and considered way,” Forgeron continues.

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1 Comment » for Standard would help enhance flood resilience of new communities: report
  1. Robert Muir says:

    The standard would indeed enhance the resiliency of new subdivisions, but clarification is required on statements on “costly and unremitting flood damage” since most urban flooding is not in new subdivisions – extensive damages are actually old pre 1980’s ones where there are very limited infrastructure design practices (from the 1920’s to 1970’s) and sometimes floodplain encroachment dating back over 100 years before we even mapped floodplains.

    The way to address extensive damages most cities are experiencing is to focus on remediation of OLD subdivisions. Metaphorically, that is, let’s get the old Pintos off the road instead of polishing up the new Cadillacs.

    Clarification is also required on the drivers for flood mitigation efforts. It truly is the “old standards” and not the “new rain”. Canadian Underwriters has clarified this in the past:

    .. and should remain consistent. As CU noted before:

    “Associate Editor’s Note: In the 2012 report Telling the Weather Story, commissioned to the Institute for Catastrophic Loss Reduction by the Insurance Bureau of Canada, Professor Gordon McBean writes: “Weather events that used to happen once every 40 years are now happening once every six years in some regions in the country.” A footnote cites “Environment Canada: Intensity-Duration-Frequency Tables and Graphs.” However, a spokesperson for Environment and Climate Change Canada told Canadian Underwriter that ECCC’s studies “have not shown evidence to support” this statement. ”

    It may be worth clarifying that higher extreme rain stress may exist in some regions of Canada, and specify any of those. The article suggests it is a consistent trend but ECCC does not support that.

    For more details on the ECCC extreme rain trend data and their publication findings, this is a complete summary considering the most up to date Engineering Climate Datasets (version 2.3):

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