Changes

[[File:Pollution hot spots.jpg|thumb|600px| Examples of activities that can lead to a source area being deemed a "Pollution hot spot" when it comes to surface runoff pollution (Photo Source: Müller et al. 2020<ref>Müller, A., Österlund, H., Marsalek, J. and Viklander, M. 2020. The pollution conveyed by urban runoff: A review of sources. Science of the Total Environment, 709, p.136125. https://www.sciencedirect.com/science/article/pii/S0048969719361212#f0010</ref>).]]

[[File:Pollution hot spots.jpg|thumb|600px| Examples of activities that can lead to a source area being deemed a "Pollution hot spot" when it comes to surface runoff pollution (Photo Source: Müller et al. 2020<ref>Müller, A., Österlund, H., Marsalek, J. and Viklander, M. 2020. The pollution conveyed by urban runoff: A review of sources. Science of the Total Environment, 709, p.136125. https://www.sciencedirect.com/science/article/pii/S0048969719361212#f0010</ref>).]]

An area, for example that contains highly densified road networks and industrial areas that require large amounts of de-icing [[salt| road salt]] in the winter and experiences heavy traffic daily, make it a significant source of sodium, chloride, petroleum based hydrocarbons, [[heavy metals]] and finally pesticides to keep lawns green during the summer months. On the other hand a source area such as a [[Green roof| green roof]] is only subject to atmospheric deposition of contaminants and isn't subjected to vehicular traffic sand, [[salt]] nor other de-icing agents. As a result, runoff from roofs typically contains significantly lower levels of [[heavy metals]], petroleum hydrocarbons, chloride or sodium levels and with more land in residential areas and less road networks is generally more suitable for safe infiltration of this runoff.

An area, for example that contains a high density of roads and industrial areas that require large amounts of de-icing [[salt| road salt]] in the winter and experiences heavy traffic daily, make it a significant source of sodium, chloride, petroleum based hydrocarbons and [[heavy metals]]. On the other hand a source area such as a roof is only subject to atmospheric deposition of contaminants and isn't typically subjected to vehicular traffic, sand, [[salt]] nor other de-icing agents. As a result, roof runoff typically contains significantly lower levels of [[heavy metals]], petroleum hydrocarbons, salt.

Certain source areas known as "pollution hot spots" have a higher chance to create contaminated surface level runoff due to given activities occurring and associated contaminant types present on site (i.e. vehicle fueling stations, landfills, certain agricultural practices, manufacturing and construction sites, etc. As a result of this different runoff contamination levels also limit the types of treatment opportunities and practices that can be implemented in varying source water areas. It is important that stormwater management plans be developed with consideration of the different types of runoff source areas that will be present, and recognition of source

Certain source areas known as "pollution hot spots" have a higher chance to create contaminated surface level runoff due to given activities occurring and associated contaminant types present on site (i.e. vehicle fueling stations, landfills, certain agricultural practices, manufacturing and construction sites, etc. As a result of this different runoff contamination levels also limit the types of treatment opportunities and practices that can be implemented in varying source water areas. It is important that stormwater management plans be developed with consideration of the different types of runoff source areas that will be present, and recognition of source

areas with low to moderate contamination potential that represent opportunities for [[Rainwater Harvesting| rainwater harvesting]], [[permeable pavements]] and other stormwater infiltration practices. Furthermore, it is vital to ensure that relatively clean runoff is not mixed with lesser quality runoff from surfaces that are subject to higher levels of contamination, rendering it less suitable for infiltration or harvesting.  

areas with low to moderate contamination potential that represent opportunities for [[Rainwater Harvesting| rainwater harvesting]], [[permeable pavements]] and other stormwater infiltration practices. Furthermore, it is important to ensure that relatively clean runoff is not mixed with lesser quality runoff from surfaces that are subject to higher levels of contamination, rendering it less suitable for infiltration or harvesting.  

These different source areas and associated runoff characteristics can be viewed in the table below:

A summary of source area types, associated runoff characteristics and stormwater BMP opportunities and pretreatment requirements can be viewed in the table below: