Source and on-site controls for municipal drainage systems
Posted January 2006
The National Guide to Sustainable Municipal Infrastructure recently released another in its “best practice” series. Source and On-Site Controls for Municipal Drainage Systems provides a brief overview of the rationale behind stormwater management programs, and explains why implementing run-off controls is important in a sustainable development context.
The executive summary explains that, “In the past, water management activities have often been based on singular practices that addressed individual needs and crises. In later years, there has been an evolution to multiple objective programs that manage water supply and conservation, with preservations of surface water and natural systems being a main objective.”
It goes on to state that, “As stormwater run-off can cause or accentuate flooding, and is a major source of pollution to our wetlands, rivers, lakes, and estuaries, local governments must take responsibility for its appropriate control.” Using the concept of a treatment train, the guide defines five different levels of control: pollution prevention planning, source control, on-site control, conveyance control, and end-of-pipe control. The guide addresses the second and third levels: source control and on-site control.
As stated in the executive summary, “Source controls are measures designed to minimize the generation of, and entry of pollutants into, stormwater run-off, with emphasis on non-structural and semi-structural measures applied at or near source. On-site (or lot-level) controls are practices that reduce run-off volumes and/or treat stormwater before it reaches a municipal conveyance system.”
The guide discusses the degree of effectiveness of different controls, the selection of appropriate best practices, related costs, and operation/maintenance issues. As much as possible, design aspects and references related to cold-climate conditions are highlighted to reflect a Canadian perspective.