Low Impact Development (LID) Location Study

The City of Edmonton will conduct a study on Low Impact Development (LID) approaches to stormwater management to achieve objectives for runoff volume reductions and pollutant control compared to existing levels based on cost benefit and return on investment. LID practices to be explored will include bio-retention (rain gardens), bioswales, green roofs, permeable pavement, box planters, naturalized drainage ways, and rainwater harvesting for re-use. One of the primary environmental objectives of the study will be to identify the number and type of LID practices needed in mature and industrial areas to achieve net zero increase in average annual total suspended solids and total phosphorus load discharged from Edmonton to the North Saskatchewan River in the short (three year), medium (ten years), and long term (30 years), as defined in the City’s Total Loadings Plan. LID practices will be sized to treat the 90th percentile rainfall depth to capture the most pollutant-laden urban runoff during first flush events. In addition to urban runoff, combined sewer overflows (CSOs) are also a major source of pollutant loading from Edmonton to the North Saskatchewan River and other water bodies in the City. Another environmental objective of this study is to determine the scale of LID implementation (both number and size of LIDs) required to reduce average annual CSO volumes in areas of Edmonton serviced by combined sewer systems. The study will also make recommendations for LID standards and by-laws for other developing areas of the City to build sustainable, resilient stormwater management systems in the areas upland of the City core. Finally, the project will advance the implementation stages by identifying publicly-owned sites for LID retrofits including feasibility-level analysis as well as prioritizing and elaborating a detailed sub watershed plan. Throughout the study, City staff will remain engaged in the project through workshops that will explore the holistic benefits of LID implementation, address the challenges of LID in city streets, and explore opportunities for City LID implementation through the existing green street programs. The final deliverable will be a final report on City-wide LID implementation recommendations. (Project description from original funding application)