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==Overview==

==Overview==

Underground infiltration systems is a general term that refers to best management practices (BMPs) that capture and temporarily store stormwater from hard surfaces. These systems treat stormwater by detaining it to allow suspended sediments to settle out and soaking it into the ground where it is filtered and cleansed by interaction with [[Soil groups|soil]]. Runoff water is delivered to the practice through [[pipes]] connected to catchbasins, hydrodynamic (i.e., [[ Oil and grit separators|oil and grit]]) separators, filters, manholes, [[underdrains|sub-drains]] of other features or roof downspouts. They are installed below the local maximum frost penetration depth to ensure they continue to drain year-round. Water that is in excess of the storage capacity overflows to an adjacent drainage system (e.g., municipal storm sewer or other BMP), typically via pipe or manhole containing a [[Flow through riser|control structure]] (e.g., weir wall), to safely convey flows during flood events. Depending on the permeability of the underlying soil, such practices may be designed without a sub-drain for full infiltration or with a sub-drain for partial infiltration. The sub-drain pipe may feature a flow restrictor (e.g., orifice cap, valve) for gradually releasing detained water and optimizing the amount drained by infiltration. <br>

[[Green roofs]] are engineered rooftop design features that allow the growth of [[vegetation]] on rooftops and have numerous benefits. These LID BMPs can also be referred to as vegetated roofs, rooftop gardens or eco-roofs. A green roof acts like a lawn, meadow or garden by intercepting and absorbing a portion of the rainwater or snowmelt that falls on it. The typical layers of a green roof (in ascending order from the roof surface) include a water-proofing membrane, drainage layer, lightweight growing media layer and the vegetation. Excess water that is not absorbed by the [[Plant selection|growing media]] or vegetation is collected by the underlying drainage layer, directed to [[Overflow|outlet]] structures and conveyed via the roof drainage system to another BMP or the municipal storm sewer system. A portion of the water absorbed by green roofs is returned to the atmosphere by evaporation and transpiration by plants. Green roofs are typically designed to retain precipitation from small to medium-sized (e.g., 5 to 25 mm rainfall depth) storm events. Overflow outlets are necessary to safely convey flows from major storm events.

 

Some of the benefits of [[green roofs]] include:

*The ability to reduce the quantity of pollutants and [[Runoff volume control targets|runoff]] being discharged to municipal storm sewers and receiving waters (i.e., rivers, lakes and [[wetlands]]);

*Growing media and [[plants]] retain pollutants deposited from the atmosphere and reduce [[Heavy metals|metals]] and other pollutants from conventional roof materials transported by runoff;

*Can provide aesthetic value as attractive landscaped features. <br>

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[[File:Plan & profile view Infilt underground.PNG|thumb|400px|General plan and profile (cross-section) views showcasing key components and sections of a typical [[infiltration trench]].]]

[[File:Layers green roof.PNG|thumb|400px|Generalized cross-section view of a green roof showing key components and common layers that make up this LID BMP (TRCA, 2018)<ref name="example1" />]]

{{textbox|Key components of Underground Infiltration Systems to pay close attention to are the:  

{{textbox|Key components of Underground Infiltration Systems to pay close attention to are the:  

*[[Inlets]]

*[[Green roof media|Filter Bed / Growing Medium]]

*[[Underdrains|Sub-Drains]]

*[[Vegetation]]

*[[Wells|Monitoring Wells]]

*[[Green roofs#Design|Protective layers]]

*[[Green roofs#Irrigation|Irrigation System]]

*[[Overflow|Overflow outlets]]}}

*[[Overflow|Overflow outlets]]}}

Trash, debris and sediment builds up at these locations and can prevent water from flowing into or out of the practice.

Trash, debris and sediment builds up at these locations and can prevent water from flowing into or out of the practice.

*'''[[Soakaways]]''': Typically service individual lots and receive only roof and walkway runoff but can also be designed to receive overflows from other BMPs (e.g., [[rainwater harvesting|rain barrels]] or [[Rainwater harvesting|cisterns]], [[rain gardens]], [[green roofs]]. Also known as infiltration galleries, French drains, [[Dry well|dry wells]] or soakaway pits.

*'''[[Soakaways]]''': Typically service individual lots and receive only roof and walkway runoff but can also be designed to receive overflows from other BMPs (e.g., [[rainwater harvesting|rain barrels]] or [[Rainwater harvesting|cisterns]], [[rain gardens]], [[green roofs]]. Also known as infiltration galleries, French drains, [[Dry well|dry wells]] or soakaway pits.

*'''[[Infiltration trenches]]''': Linear oriented soakaways designed to fit into narrow strips of land between structures or properties, or along road rights-of-way; can also receive road runoff with adequate pretreatment devices upstream of inlets.  

*'''[[Infiltration trenches]]''': Linear oriented soakaways designed to fit into narrow strips of land between structures or properties, or along road rights-of-way; can also receive road runoff with adequate pretreatment devices upstream of inlets.  

*'''[[Infiltration chambers]]''': Include a range of proprietary modular structures installed underground that create large void spaces for temporary storage of stormwater while providing sufficient load bearing capacity to allow construction of structures on top of them. Applications are similar to infiltration trenches. Also known as [[Infiltration chambers: Specifications|infiltration tanks or vaults]].

'''[[Green roofs#Design|Intensive green roofs]]''' contain greater than 15 cm depth of growing media, can be planted with deeply rooted plants (e.g., shrubs and trees) and can be designed to handle pedestrian traffic.

*'''[[Exfiltration trenches|Perforated pipe storm sewer systems]] or [[Exfiltration trenches]]''': Linear-oriented [[infiltration trenches]] installed parallel with conventional storm sewer pipes and catchbasins that receive stormwater from them. May include manholes with [[Flow through riser|perforated risers]]. Also known as exfiltration storm sewer, percolation drainage, or clean water collector systems.

'''[[Green roofs#Design|Extensive green roofs]]''' consist of a thinner growing media layer (15 cm depth or less) and are typically planted with.

'''[[Blue roofs]]''' are systems that temporarily capture rainwater using the roof as storage and allow it to evaporate and/or to be used for non-potable requirements (i.e. irrigation, toilet flushing, truck washing) and ultimately offset potable water demands.

==Inspection and Testing Framework==

==Inspection and Testing Framework==