Many cities in Canada are already facing substantial issues of surface water runoff overtaxing local sewer infrastructure, leading to higher maintenance and treatment costs and increasing the risk of basement flooding due to sewer backups. With climate change projected to increase the number of high-precipitation events, which are more likely to cause sewer backups as the pipes are filled to excess extremely quickly, this issue is likely to only increase in importance as the years go on. Implementing low impact development methods would be economically justified by reducing sewer loads in the absence of climate change. However, given that that is not the case, mandating that new developments retain local runoff on-site is an especially forward-looking plan, as climate change is expected to increase the frequency and magnitude of high-intensity precipitation events. In the specific case of the Currie Barracks, the site is also a former military installation and the surface water may carry many additional contaminants from the unique nature of its previous use.
In an effort to improve the city’s resilience in the face of an increasing intensity and frequency of rainfall events due to climate change, the City of Calgary, working with developers, has mandated that the brownfield development of a former Canadian Forces barracks in the city will include substantial use of low impact design methods. Low impact design methods are suite of physical design choices that help to retain stormwater onsite, reducing the load on municipal sewer systems and, therefore, sewer backup flooding. In this particular project, the construction of swales and rain gardens are the primary method of intercepting overland flow. The development is ongoing, but at the moment the site has proven successful at retaining most precipitation onsite.