Extreme rainfall events temporarily increase demands on stormwater systems and increase the volume of rainwater flowing into streams and rivers. As climate change increases the frequency and intensity of such rainfall events, Victoria’s current stormwater infrastructure may become overwhelmed. Risks associated with these climate-related impacts include potential extensive damage from sanitary waste backing up into homes and environmental damage as untreated sanitary waste is discharged into streams and lakes. The 2012 Canadian Infrastructure Report Card noted that 40 to 50 percent of participating local governments have no data on the state of their buried infrastructure. Twenty percent of Canada’s wastewater and stormwater infrastructure was estimated to be in “fair” to “very poor” condition. Local governments likely need more than $55 billion to replace these failing systems. In Victoria, a city with several older neighbourhoods, aging sewers and wastewater infrastructure meant the City was vulnerable to the impacts of climate change, as increased extreme rainfall events would result in greater stormwater inflow and infiltration. Since the damage from such inflow and infiltration was largely preventable by proactively rehabilitating failing infrastructure, the City of Victoria identified the need to establish and implement a plan that would better control the inflow and infiltration of rainwater into the sanitary sewer system. Understanding the core issue and the City’s vulnerability to climate change, Victoria moved to the planning phase of their adaptation efforts.
The Capital Regional District’s Liquid Waste Management Plan was introduced in 2009 to combat against largely preventable losses as a result of aging sewers and wastewater infrastructure being unable to cope with increased extreme rainfall events due to climate change. The plan mandated that each municipality in the region should not be exposed to peak wet weather sanitary sewer flows that exceed four times average dry weather flows. In the City of Victoria, flows were known to be above this target, making the region extremely vulnerable to the impacts of climate change and necessitating adaptation efforts. Seeking to establish and implement a plan to better control the inflow and infiltration of rainwater into the sewer system, Victoria launched an in-depth study focused on determining how stormwater was entering sanitary sewer pipes in the James Bay area. With aging sewer infrastructure in the region, extreme rain events threatened the backup of sanitary waste into homes and the discharge of untreated sewer water into the environment. Video inspections of the sewer system, smoke and dye tests, and the collection of flow monitoring data offered insights on sources of inflow and infiltration. The design phase of the James Bay project tested four different approaches to reduce inflow and infiltration, with a focus on trenchless technologies. During the evaluation phase, the reduction of stormwater in sewer pipes was measured once the rehabilitation work was completed. This comprehensive study revealed that mainline and lateral sewer rehabilitation contributed to a 60 percent reduction in stormwater inflow and infiltration. The results of the various tests conducted in James Bay helped the engineering department in Victoria to establish a long-term plan to best manage their current infrastructure and decide where to prioritize rehabilitation practice.