Changes

[[File:Treatmenttrain TRCA.JPG|thumb|600px|Example of a generalization of utilizing a “Treatment Train Approach” illustrated here. Using [[permeable pavement]] as a source control/lot control on your business/residential property, effluent then flows into conveyance control such as an [[Exfiltration trench|exfiltration system]], used in conjunction with the minor stormwater system as shown above. and then flowing into a stormwater management pond (wet pond) for additional erosion and flood control (TRCA, n.d. Understand - Stormwater Management. Accessed: https://trca.ca/conservation/stormwater-management/understand/</ref>]]

[[File:Treatmenttrain TRCA.JPG|thumb|600px|Example of a generalization of utilizing a “Treatment Train Approach” illustrated here. Using [[permeable pavement]] as a source control/lot control on your business/residential property, effluent then flows into conveyance control such as an [[Exfiltration trench|exfiltration system]], used in conjunction with the minor stormwater system as shown above. and then flowing into a stormwater management pond (wet pond) for additional erosion and flood control (TRCA, n.d. Understand - Stormwater Management. Accessed: https://trca.ca/conservation/stormwater-management/understand/</ref>]]

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==Overview==

==Overview==

A treatment train uses a combination of lot-level or source (LID), conveyance and/or end-of-pipe practices to meet water quality, water quantity, water balance, and erosion design criteria for the site.  These may be implemented to reduce the burden of facility maintenance, address a broader range of design criteria, increase overall treatment system performance, and/or control the rate of flow through downstream facilities.

A treatment train uses a combination of lot-level or source (LID), conveyance and/or end-of-pipe practices to meet water quality, water quantity, water balance, and erosion design criteria for the site.  These may be implemented to reduce the burden of facility maintenance, address a broader range of design criteria, increase overall treatment system performance, and/or control the rate of flow through downstream facilities.

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'''Performance calculation''': If the downstream facility provides filtration, such as [[bioretention]] or [[Infiltration trenches|stone filled trenches]], the overall water quality performance of this facility would not increase with [[pretreatment]] because the coarse sediment and debris captured by the pretreatment device would be removed by the downstream facility even in the absence of pretreatment.  The purpose of adding pre-treatment is to prevent clogging or filling and thereby reduce the cost and effort of long term [[Inspections and maintenance|maintenance]] and delay requirements for major facility [[Maintenance, Rehabilitation and Repair|rehabilitation or replacement]].

'''Performance calculation''': If the downstream facility provides filtration, such as [[bioretention]] or [[Infiltration trenches|stone filled trenches]], the overall water quality performance of this facility would not increase with [[pretreatment]] because the coarse sediment and debris captured by the pretreatment device would be removed by the downstream facility even in the absence of pretreatment.  The purpose of adding pre-treatment is to prevent clogging or filling and thereby reduce the cost and effort of long term [[Inspections and maintenance|maintenance]] and delay requirements for major facility [[Maintenance, Rehabilitation and Repair|rehabilitation or replacement]].

[[File:Sump inelt to chamber system.JPG|thumb|500px|Example of a [[Pretreatment#Concentrated underground flow|overland flow sump inlet]] allowing sediment to settle out of influent stormwater before entering a large infiltration chamber housed under a parking lot/ The outlet control device can then drain into a [[dry pond]] furthu downstream or offsite (Source: Philadelphia Water Department. 2020)<ref>Philadelphia Water Department. 2020. Stormwater Management Guidance Manual: Version 3.2. Accessed from: https://www.pwdplanreview.org/upload/manual_pdfs/PWD-SMGM-v3.2-20201001.pdf</ref>]]

[[File:Sump inelt to chamber system.JPG|thumb|500px|Example of a [[Pretreatment#Concentrated underground flow|overland flow sump inlet]] allowing sediment to settle out of influent stormwater before entering a large infiltration chamber housed under a parking lot/ The outlet control device can then drain into a [[dry pond]] furthu downstream or offsite (Source: Philadelphia Water Department. 2020)<ref>Philadelphia Water Department. 2020. Stormwater Management Guidance Manual: Version 3.2. Accessed from: https://www.pwdplanreview.org/upload/manual_pdfs/PWD-SMGM-v3.2-20201001.pdf</ref>]]

These types of treatment trains combine practices that address different [[Screening LID options|design criteria]], in recognition that most individual stormwater facility types do not meet all design criteria as stand-alone facilities.  For instance, [[SWM ponds|stormwater wet ponds]] may provide [[water quality]], erosion and flood control but not water balance control (i.e. [[Runoff volume control targets|runoff volume control]]).  [[Bioretention]] provides good water quality and water balance control but are rarely designed for flood control.   

These types of treatment trains combine practices that address different [[Screening LID options|design criteria]], in recognition that most individual stormwater facility types do not meet all design criteria as stand-alone facilities.  For instance, [[SWM ponds|stormwater wet ponds]] may provide [[water quality]], erosion and flood control but not water balance control (i.e. [[Runoff volume control targets|runoff volume control]]).  [[Bioretention]] provides good water quality and water balance control but are rarely designed for flood control.   

===3. Treatment trains designed to enhance overall treatment system performance===

===3. Treatment trains designed to enhance overall treatment system performance===

[[File:Storm bmps rev3.png|thumb|500px|An example of a treatment train approach used to enhance treatment performance in an area with limited surface area due to parking and the adjacent municipal roadway. In this example water is able to be collected and then conveyed from a [[green roof]] system, a [[bioswale]] and [[permeable pavement]] parking lot, through an [[OGS|oil and grit separator]] and then to an [[Infiltration chamber]] or an underground [[cistern]] tank. Clean water can then be reused onsite or overflow out to the municipal storm sewer and receiving waterbody (City of Saskatoon, 2023).<ref>City of Saskatoon. 2023. Storm Water Management Credit Program. Image courtesy of the City of Mississauga. Accessed: https://www.saskatoon.ca/services-residents/power-water-sewer/storm-water/storm-water-management-credit-program</ref>]]

[[File:Storm bmps rev3.png|thumb|400px|An example of a treatment train approach used to enhance treatment performance in an area with limited surface area due to parking and the adjacent municipal roadway. In this example water is able to be collected and then conveyed from a [[green roof]] system, a [[bioswale]] and [[permeable pavement]] parking lot, through an [[OGS|oil and grit separator]] and then to an [[Infiltration chamber]] or an underground [[Rainwater harvesting|cistern]] tank. Clean water can then be reused onsite or overflow out to the municipal storm sewer and receiving waterbody (City of Saskatoon, 2023).<ref>City of Saskatoon. 2023. Storm Water Management Credit Program. Image courtesy of the City of Mississauga. Accessed: https://www.saskatoon.ca/services-residents/power-water-sewer/storm-water/storm-water-management-credit-program</ref>]]

The design intent of these treatment trains is to enhance overall system performance.  The previous category of treatment train may enhance performance, but the objective may not always be to address a broader range of stormwater criteria.   

The design intent of these treatment trains is to enhance overall system performance.  The previous category of treatment train may enhance performance, but the objective may not always be to address a broader range of stormwater criteria.   

==Treatment trains with runoff volume reduction facilities==

==Treatment trains with runoff volume reduction facilities==

These types of treatment trains are becoming more common because they can achieve multiple [[Runoff volume control targets|stormwater control]] and [[water quality|treatment objectives]].  Since wet ponds alone do not achieve stormwater water balance criteria, they must be supplemented with facilities providing runoff volume reductions to meet regulatory requirements. If site water balance objectives require control of the 90th percentile event (roughly 25 – 30 mm in most jurisdictions), the same infiltration facilities may also be used to treat the water quality storm (typically 25 mm), allowing for a [[dry pond]] or similar temporary detention facility to be used at the end-of-pipe to meet flood and erosion control criteria.

These types of treatment trains are becoming more common because they can achieve multiple [[Runoff volume control targets|stormwater control]] and [[water quality|treatment objectives]].  Since wet ponds alone do not achieve stormwater water balance criteria, they must be supplemented with facilities providing runoff volume reductions to meet regulatory requirements. If site water balance objectives require control of the 90th percentile event (roughly 25 – 30 mm in most jurisdictions), the same infiltration facilities may also be used to treat the water quality storm (typically 25 mm), allowing for a [[dry pond]] or similar temporary detention facility to be used at the end-of-pipe to meet flood and erosion control criteria.