Lot-level practices to control urban flood risk and mitigate basement flooding in Canada

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Water damage due to basement flooding is one of the largest sources of home insurance claims in Canada. A drastic increase in economic damages associated with basement flooding has been observed in recent years. Today, it is estimated that approximately $1.8 billion in insured losses for water damage due to basement flooding is incurred every year in Canada. The sensitivity to basement flooding and increased insured losses are exacerbated by the increase in frequency and magnitude of extreme precipitation events, urbanization and changes in land-use, and the age and condition of municipal infrastructure (e.g., sewer systems). Basement flooding, which primarily occurs due to inadequate sanitary or storm sewer systems or insufficient foundation and lot drainage systems, can result from infiltration, overland flooding and sewer backup. Numerous factors influence the occurrence of basement flooding, including stormwater management infrastructure and lot-level technologies or approaches that protect homes from basement flooding. Lot-level approaches can include foundation drainage systems (e.g., weeping tile systems) to reduce the occurrence of infiltration flooding, low impact development measures (e.g., bio-swales, infiltration trenches, etc.) to reduce the occurrence of overland flooding, and backwater valves to reduce the occurrence of sewer backup. The goal of this research is to evaluate the performance of various technologies and approaches to reduce the risk of occurrence of basement flooding. In particular, this research will investigate the performance of backwater valves to reduce the risk of basement flooding due to sewer surcharge and evaluate the effect of low impact development measures on improved urban drainage and sewer network response to extreme events. Results will be of relevance to insurance companies, municipalities, the plumbing industry, engineering consulting companies and Canadian homeowners. This research will assist in developing Canadian homes and communities that are more resilient to the adverse effects of urban flooding events and will seek to reduce the economic damages experienced as a result of basement flooding.