Changes

[[File:Filtration.png|right|frame|Media based systems are depth filters that capture particles both on the surface and within the media matrix.  Membrane filters are surface filters that remove all particles greater than a specified size at the surface of the filter.  Membranes are typically much thinner than shown in the diagram above. Both filtration systems can be oriented vertically or horizontally.

[[File:Filtration.png|500px|right|frame|Media based systems are depth filters that capture particles both on the surface and within the media matrix.  Membrane filters are surface filters that remove all particles greater than a specified size at the surface of the filter.  Membranes are typically much thinner than shown in the diagram above. Both filtration systems can be oriented vertically or horizontally.

(Source: Green Synergy Engineering)]]

(Source: Green Synergy Engineering)]]

==Applications==

==Applications==

Stormwater practices that use filtration as a mechanism for treatment of runoff include:

Stormwater practices that use filtration as a mechanism for treatment of runoff include:

*[[Bioretention]] technologies have been shown to effectively filter sediment from parking lot, road and residential runoff. <ref>Sustainable Technologies Evaluation Program. 2019. Comparative Performance Assessment of Bioretention in Ontario. https://sustainabletechnologies.ca/app/uploads/2019/10/STEP_Bioretention-Synthesis_Tech-Brief-New-Template-2019-Oct-10.-2019.pdf</ref>

*[[Bioretention]] technologies have been shown to effectively filter sediment from parking lot, road and residential runoff. <ref>Sustainable Technologies Evaluation Program. 2019. Comparative Performance Assessment of Bioretention in Ontario. https://sustainabletechnologies.ca/app/uploads/2019/10/STEP_Bioretention-Synthesis_Tech-Brief-New-Template-2019-Oct-10.-2019.pdf</ref>

===Sizing===

===Sizing===

When sizing filtration systems for specific sites using local historical rainfall records, several key system design parameters need to be considered.  These are defined in the sizing section of the [[Filtration MTD]] page.  

When sizing filtration systems for specific sites using local historical rainfall records, several key system design parameters need to be considered.  These are defined in the sizing section of the [[Filtration MTD]] page.  

Non-proprietary [[bioretention]] systems are sized as filters much more conservatively based on design storms, surface ponding depth and [[Flow through media|minimum media infiltration rate]].  The ratio of drainage area imperviousness to the surface area of bioretention facilities (referred to as the impervious-to-pervious ratio) is often many times lower than that for filtration MTDs.  This ensures longer intervals for sediment maintenance and significant reductions in stormwater volumes through infiltration.

Non-proprietary [[bioretention]] systems are sized as filters much more conservatively based on design storms, surface ponding depth and [[Flow through media|minimum media infiltration rate]].  The ratio of drainage area imperviousness to the surface area of bioretention facilities (referred to as the impervious-to-pervious ratio) is often many times lower than that for filtration MTDs.  This ensures longer intervals for sediment maintenance and significant reductions in stormwater volumes through infiltration.

==Maintenance considerations==

==Maintenance considerations==

[[File:Screenshot 2025-07-14 135310.png|300px|thumb|right|Filter media replacement in bioretention system (Filterra®)<ref>filterra-vault-om.pdf</ref>]]

[[File:MaintenancePICP.png|thumb|300px|Vehicle used for vacuum maintenance of permeable pavements (Source: STEP). ]]

[[Inspections and maintenance#Practice-specific Inspection and Maintenance|Practice-specific maintenance guides]] are available for each LID BMP. General maintenance considerations for filter-based LIDs include:

[[Inspections and maintenance#Practice-specific Inspection and Maintenance|Practice-specific maintenance guides]] are available for each LID BMP. General maintenance considerations for filter-based LIDs include:

*'''Inspection and maintenance frequency''': Routine inspections and maintenance are needed to assess and resolve issues, such as [[Sedimentation|sediment]] buildup. [[Maintenance, Rehabilitation and Repair|Frequency of visits]] depends on a variety of factors. LID BMP designs should include safe access for maintenance and inspection crews and confined space entry procedures should be considered for subsurface systems.

*'''Inspection and maintenance frequency''': Routine inspections and maintenance are needed to assess and resolve issues, such as [[Sedimentation|sediment]] buildup. [[Maintenance, Rehabilitation and Repair|Frequency of visits]] depends on a variety of factors. LID BMP designs should include safe access for maintenance and inspection crews and confined space entry procedures should be considered for subsurface systems.