Level of service (LOS) assessment of stormwater infrastructure systems: a case study for cost-benefit analysis of low-impact development practices

Stormwater infrastructure system (SWIS) is a main component of a municipal infrastructure system that safely passes excess runoff, controls floods, and manages pollutant discharges. A comprehensive literature review has revealed that stormwater infrastructure level of service (LOS) assessment, an important step in asset management, has been abstractly defined. LOS assists in infrastructure performance assessment as well as investment decision-making. This research proposes a methodological framework for LOS assessment of SWIS and adopts the proposed method in asset management decision-making. A hierarchical framework was developed to assess the LOS by using key performance indicators. The proposed framework was demonstrated in a case study for a municipality in Southwestern ON. To improve the LOS of sub-catchments with low LOS, low-impact development (LID) controls were proposed. The cost-benefit analysis revealed that an investment of $110 950 in LIDs could increase the LOS by 26.4% (from medium to good).