Changes

With respect to potential contaminants or pollutants in stormwater surface runoff the types and levels of these contaminants varies widely depending on the associated activities, characteristics and makeup of the local source water area.

With respect to potential contaminants or pollutants in stormwater surface runoff the types and levels of these contaminants varies widely depending on the associated activities, characteristics and makeup of the local source water area.

An area, for example that contains highly densified road networks and industrial areas that require large amounts of de-icing rock 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 [Blue 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 highly densified road networks and industrial areas that require large amounts of de-icing rock 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 [Blue 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.

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

|Roof drains, roof terrace area drains, [[overflow]] from green roofs

|Roof drains, roof terrace area drains, [[overflow]] from green roofs

|

|

Moderately clean water, contaminants may include asphalt granules, low levels of hydrocarbons and [[metals|Heavy metals]] from decomposition of roofing materials, animal droppings, natural organic matter and fall out from airborne pollutants, potentially warm water.

Moderately clean water, contaminants may include asphalt granules, low levels of hydrocarbons and [[Heavy metals|metals]] from decomposition of roofing materials, animal droppings, natural organic matter and fall out from airborne pollutants, potentially warm water.

|

|

*Infiltration ([[Enhanced swales]], [[Bioswales]], [[Green Roofs]], [[Bioretention]], [[Permeable pavements]], etc.);

*Infiltration ([[Enhanced swales]], [[Bioswales]], [[Green Roofs]], [[Bioretention]], [[Permeable pavements]], etc.);

*Filtration ([[Stormwater Tree Trenches]], [[Soil cells]], [[Stormwater planters]]);

*Filtration ([[Stormwater Tree Trenches]], [[Soil cells]], [[Stormwater planters]]);

*Harvesting with [[rain barrels]] or [[cisterns|Infiltration chambers]] and use for both indoor and outdoor non-potable purposes (e.g., irrigation, toilet flushing) after [[Pretreatment]];

*Harvesting with [[rain barrels]] or [[cisterns|Infiltration chambers]] and use for both indoor and outdoor non-potable purposes (e.g., irrigation, toilet flushing) after [[Pretreatment]];

*Attenuation and treatment in [[wet pond|SWM ponds]] or [[wetland]] detention facility.

*Attenuation and treatment in [[SWM ponds|wet pond]] or [[wetland]] detention facility.

|

|

Runoff should be treated with a [[sedimentation and/or filtration practice|Pretreatment]] prior to infiltration. Where possible, runoff should not be directed to end-of-pipe facilities to capitalize on potential for infiltration or harvesting. Flow moderation (quantity control) prior to discharge to receiving watercourse is required.

Runoff should be treated with a [[Pretreatment|sedimentation and/or filtration practice]] prior to infiltration. Where possible, runoff should not be directed to end-of-pipe facilities to capitalize on potential for infiltration or harvesting. Flow moderation (quantity control) prior to discharge to receiving watercourse is required.

|-

|-

|Low and medium traffic roads and parking lots, driveways, pedestrian plazas, walkways

|Low and medium traffic roads and parking lots, driveways, pedestrian plazas, walkways

|

|

Moderately clean water, contaminants may include low levels of sediment, de-icing salt constituents, hydrocarbons, [[metals|Heavy metals]] and natural organic matter. Typically warm water.

Moderately clean water, contaminants may include low levels of sediment, de-icing salt constituents, hydrocarbons, [[Heavy metals|metals]] and natural organic matter. Typically warm water.

|

|

*Infiltration ([[Grass Swales]], [[Bioswales]], [[Green Roofs]], [[Bioretention]], [[Permeable pavements]], etc.);

*Infiltration ([[Grass Swales]], [[Bioswales]], [[Green Roofs]], [[Bioretention]], [[Permeable pavements]], etc.);

|High traffic roads and parking lots

|High traffic roads and parking lots

|

|

Potential for high levels of contamination with sediment, deicing [[salt]] constituents hydrocarbons and [[metals|heavy Metals]]. Typically warm water.

Potential for high levels of contamination with sediment, deicing [[salt]] constituents hydrocarbons and [[Heavy metals|metals]]. Typically warm water.

|

|

*Filtration after sedimentation [[Pretreatment]];

*Filtration after sedimentation [[Pretreatment]];

|"Pollution hot spots" such as vehicle fueling, servicing or demolition areas, outdoor storage and handling areas for hazardous materials, some heavy industry/construction sites

|"Pollution hot spots" such as vehicle fueling, servicing or demolition areas, outdoor storage and handling areas for hazardous materials, some heavy industry/construction sites

|

|

Potential for high levels of contamination with sediment, deicing [[salt]] constituents, hydrocarbons, [[metals|Heavy metals]], and other toxins.

Potential for high levels of contamination with sediment, deicing [[salt]] constituents, hydrocarbons, [[Heavy metals|metals]], and other toxins.

|

|

*Attenuation and treatment in [[wet pond|SWM ponds]], [[wetland]] or hybrid detention facility;

*Attenuation and treatment in [[wet pond|SWM ponds]], [[wetland]] or hybrid detention facility;