A Comprehensive Inspection Protocol to Assess Stormwater Green Infrastructure Hydraulic Performance: A Case Study for the City of Montreal

With the goal of adapting its existing sewer system to mitigate the impact of climate change and minimize combined sewer overflows, the City of Montreal has constructed over 400 stormwater green infrastructure (GI) since 2019. Following the positive response to these new infrastructures, the city anticipates undertaking additional projects in the coming years. To improve both design and maintenance of these infrastructures, a visual inspection protocol was developed collaboratively with gardeners, engineers, and technical staff. This protocol underwent bi-seasonal testing across 165 GI over the course of a year. Findings revealed that 31% of the GI required immediate retrofitting due to major technical flaws negatively affecting the hydraulic performance. Additionally, 29% displayed inadequate maintenance or required minor technical improvements. However, a noteworthy 40% of the inspected GI were found to be in fair to excellent condition, demonstrating satisfactory performance.