Changes

<br> For simple systems (typically without regulatory control), see [[Rain gardens]].

<br> For simple systems (typically without regulatory control), see [[Rain gardens]].

<br> For linear systems, which convey flow, but are otherwise similar see [[Swales|Bioswales]].

<br> For linear systems, which convey flow, but are otherwise similar see [[Swales|Bioswales]].

{{TOClimit|2}}  

{{TOClimit|2}}  

===Overview===

===Overview===

<p>Bioretention cells are one of the most well recognized form of low impact development (LID). They can fit into any style of landscape and encompass all mechanisms of action: infiltration, filtration and evapotranspiration.</p>

<p>Bioretention cells are one of the most well recognized form of low impact development (LID). They can fit into any style of landscape and encompass all mechanisms of action: infiltration, filtration and evapotranspiration.</p>

{{TextBox|1=Bioretention cells are an ideal technology for:  

{{textbox|Bioretention cells are an ideal technology for:  

*Fitting functional vegetation into urban landscapes  

*Fitting functional vegetation into urban landscapes  

*Treating runoff collected from nearby impervious surfaces}}

*Treating runoff collected from nearby impervious surfaces}}

    <p><strong>The fundamental components of a bioretention cell are:</strong>  

<strong>The fundamental components of a bioretention cell are:</strong>  

*A 'filter bed' containing an [[Bioretention: Filter media| engineered soil mix]]

*A 'filter bed' containing an [[Bioretention: Filter media| engineered soil mix]]

*A storage layer of [[Reservoir_gravel|coarse aggregate]]

*A storage layer of [[Reservoir_gravel|coarse aggregate]]

*Planting and a finishing surface layer (e.g. [[mulch]])

*Planting and a finishing surface layer (e.g. [[mulch]])

        <strong>Additional components may include:</strong>  

<strong>Additional components may include:</strong>  

*An [[underdrain]] to redistribute or remove excess water  

*An [[underdrain]] to redistribute or remove excess water  

*An [[Liner|impermeable membrane]] to prevent infiltration to soils below

*An [[Liner|impermeable membrane]] to prevent infiltration to soils below

==Planning considerations==

<h3>Space</h3>  

<p>For optimal performance bioretention facilities should receive runoff from between 5 to 20 times their own surface area. In the conceptual design stage it is recommended to set aside approximately 10 - 20 % of a catchment area to the bioretention facility. Bioretention cell(s) work best when distributed so that no one facility receives runoff from more than 0.8 Ha. Although, there is a trade off to be considered regarding distributed collection and treatment against ease of maintenance.  

As the aggregates, filter media and geotextiles are flexible, bioretention cells can be almost any shape, from very curving, soft edges with variable depth, to angular,  hard sided and uniform depth. For ease of construction and to ensure that the vegetation has adequate space, cells should be no narrower than 0.6 m at any point. As construction machinery must not be tracked into the cell, the maximum available width is 15 m with access on both sides, or 10 m with access on one side.  This should be confirmed with the contractor.

 

===Planning considerations===

<h4blue>Space</h4blue>  

<p>For optimal performance bioretention facilities should receive runoff from between 5 to 20 times their own surface area. In the conceptual design stage it is recommended to set aside approximately 10 - 20 % of a catchment area to the bioretention facility. Bioretention cell(s) work best when distributed so that no one facility receives runoff from more than 0.8 Ha. Although, there is a trade off to be considered regarding distributed collection and treatment against ease of maintenance. </p>

<p>As biomedia  and geotextiles are flexible, bioretention cells can be almost any shape, from very curving, soft edges with variable depth, to angular,  hard sided and uniform depth. For ease of construction and to ensure that the vegetation has adequate space, cells should be no narrower than 0.6 m at any point. As construction machinery must not be tracked into the cell, the maximum available width is 15 m with access on both sides, or 10 m with access on one side.  This should be confirmed with the contractor. </p>

{{:Bioretention: Context}}

{{:Bioretention: Context}}

<h4blue>Infiltration</h4blue>

<h3>Infiltration</h3>

<p>Some form of stormwater landscaping (bioretention) can be fitted into most spaces. One of the key decisions is whether to infiltrate all of some of the collected water into the native soil. Although there are some [[Infiltration#Constraints|constraints]] to infiltrating water, it is preferable to do so where possible. [[Bioretention:_Partial_infiltration|Partial infiltration]] facilities are a popular choice over 'tight' soils (infiltration ≤ 15 mm/hr). </p>

Some form of stormwater landscaping (bioretention) can be fitted into most spaces. One of the key decisions is whether to infiltrate all of some of the collected water into the native soil. Although there are some [[Infiltration#Constraints|constraints]] to infiltrating water, it is preferable to do so where possible. [[Bioretention:_Partial_infiltration|Partial infiltration]] facilities are a popular choice over 'tight' soils (infiltration ≤ 15 mm/hr).

{{:Bioretention: Variations}}

{{:Bioretention: Variations}}

<h4blue>Inlets and pretreatment options</h4blue>  

<h3>Inlets and pretreatment options</h3>  

Options for pretreatment include:

Options for pretreatment include:

*A [[gravel diaphragm]] for sheet flow

    <li>A [[gravel diaphragm]] for sheet flow </li>

*[[Vegetated filter strips]] for sheet flow

    <li>[[Vegetated filter strips]] for sheet flow </li>

*A [[Forebays|forebay]] for concentrated overground flow

    <li>A [[Forebays|forebay]] for concentrated overground flow</li>

*An [[Oil and grit separators|oil and grit separator]] for concentrated underground flow

    <li>An [[Oil and grit separators|oil and grit separator]] for concentrated underground flow </li>

 

Simple (non-treating) inlets include:

Simple (non-treating) inlets include:

*Sheet flow from a depressed curb

    <li>Sheet flow from a depressed curb</li>

*One of more [[curb cuts]]

    <li>One of more [[curb cuts]]</li>

<h3>Overflow routing</h3>  

<h4blue>Overflow routing</h4blue>  

{{:Bioretention: Routing}}

{{:Bioretention: Routing}}

<h4blue>Design for maintenance</h4blue>

<h3>Design for maintenance</h3>

 

==Design==

<h3>Sizing</h3>

 

===Design===

<h4>Sizing</h4>

{{:Bioretention: Sizing and modeling}}  

{{:Bioretention: Sizing and modeling}}  

<br>If additional storage volume is desired beneath an underdrain pipe, this may be sized as an [[Infiltration:_Sizing_and_modeling|infiltration trench]].  

<br>If additional storage volume is desired beneath an underdrain pipe, this may be sized as an [[Infiltration:_Sizing_and_modeling|infiltration trench]].  

 

==Construction==

 

 

 

===Construction===

{{:Bioretention: Construction}}

{{:Bioretention: Construction}}

==Incentives and Credits==

 

<h3>In Ontario</h3>

===Incentives and Credits===

<h4>In Ontario</h4>

<strong>City of Mississauga</strong><br>

<strong>City of Mississauga</strong><br>

The City of Mississauga has a stormwater management credit program which includes RWH as one of their recommended site strategies[https://www.mississauga.ca/portal/services/credit-program].  

The City of Mississauga has a stormwater management credit program which includes RWH as one of their recommended site strategies[https://www.mississauga.ca/portal/services/credit-program].  

<br>

<br>

<h4>LEED BD + C v. 4</h4>

<h3>LEED BD + C v. 4</h3>

{{:LEED: Rainwater management}}

{{:LEED: Rainwater management}}

<h4>SITES v.2 </h4>

<h3>SITES v.2 </h3>

 

==See Also==

[[Swales|Bioswales]]

 

[[Rain gardens]]

===See Also===

[[Trees]]

==External Links==

<li>[[Swales|Bioswales]]</li>

<li>[[Rain gardens]]</li>

<li>[[Trees]]</li>

 

===External Links===

{{:Bioretention:_External_links}}

{{:Bioretention:_External_links}}

[[Category:Infiltration]]

[[Category:Infiltration]]

[[Category:Planted]]

[[Category:Planted]]