Changes

<p>Infiltration of stormwater into underlying soils is one the priority level 1. mechanisms to achieve MOECC Runoff Volume Control targets.

Infiltration of stormwater into underlying native subgrade soils is one mechanism to achieving MECP [[runoff volume control targets]]. In many areas of Ontario, where municipal and private drinking water supplies are drawn from aquifers, it's also an important mechanism for groundwater recharge.

{{TextBox|1= Infiltration is promoted through a number of LID BMPs:

{{textbox|Drainage via infiltration be achieved through a number of LID BMP types:

*[[Infiltration chambers]] (underground)

*[[Infiltration chambers]] (underground)

*[[Infiltration trenches]] (underground)

*[[Infiltration trenches]] (underground)

*[[Dry ponds]] (surface)

*[[Exfiltration trenches| Exfiltration systems]] (underground)

*[[Bioretention cells]] (surface)

*[[Bioretention]] (surface, full- or partial-infiltration design variations)

*[[Bioswales]] (surface)

*[[Bioswales]] (surface, full- or partial-infiltration design variations)

*[[Dry ponds]] or infiltration basins (surface)

}}

}}

 

===Constraints===

==Constraints==

Infiltration practices are not recommended:

Infiltration practices are not recommended:

#over-swelling clays or unstable subsoils,

#contaminated soils or sites with high risk of contamination from on-site activities (i.e. pollution hot spots),

<li>Over swelling clays or unstable sub-soils,</li>

#on unstable or steep slopes (>15%),

<li>Over contaminated soils or sites with high risk of contamination from onsite activities, </li>

<li>In flood prone areas where the wastewater system is sensitive to groundwater conditions causing sewer backups, and where LID BMPs have been found to be ineffective,</li>

<li>In areas where the ecology and natural hydrology are dependent upon surface water,</li>

#in flood prone areas where the wastewater system is sensitive to groundwater conditions causing sewer backups,

<li>Where prohibitions and/or restrictions exist per approved Source Protection Plans (see MOECC guidance).  

#in areas where the ecology and natural hydrology are dependent upon surface water,

</ol>

#where prohibitions and/or restrictions exist per approved Drinking Water Source Protection Plans (e.g. should not be used to treat pavement runoff within 2 year time of travel wellhead protection areas; see MOECC guidance).

===Designing within constraints===

<br>

Infiltration can still be optimized over 'tight' soils with infiltration rates ≤ 15 mm/hr:

 

<li>[[Bioretention: Internal water storage |Bioretention with internal water storage]]</li>

===Designing with constraints===

<li>[[Bioretention:_Partial_infiltration|Partially infiltrating bioretention]]</li>

{{textbox|Infiltration facilities can be effective on low permeability soils with infiltration rates ≤ 15 mm/hr:

*See [[Underdrains| underdrains]] and

Where infiltration is impossible, LID design alternatives exist which can still capture and retain  stormwater:

*Results from STEP studies of infiltration facilities located on [[low permeability soils]] in Ontario.

<li>[[Bioretention: Non-infiltrating | Bioretention planters]]</li>

#the underlying bedrock is within 1 m below the bottom of the proposed BMP, or

<li>[[Green roofs]]</li>

 

The Conservation Authorities Geoscience Group has prepared a guidance document which attempts to standardize the hydrogeological study requirements for development applications made to Conservation Authorities. It is a helpful guide for all low impact development applications which include infiltration. It is provided with the caveat that not all sections or content are necessary or appropriate for every case. Pre-consultation with your local conservation authority and municipality is strongly recommended in all cases.

 

'''[http://www.lsrca.on.ca/Shared%20Documents/permits/hydrogeological%20_guidelines.pdf?pdf=Hydrogeological-Guidelines Hydrogeological Assessment Submissions Conservation Authority Guidelines for Development Applications]'''

 

See [[Design infiltration rates]]

===Planning===

==See also==

*[[Site considerations]]

<p>[[Infiltration: Testing|Infiltration tests]] must be undertaken at the location, depth and with a head of water that replicates the proposed design. </p>

[[category:Infiltration]]

[[category:Infiltration]]