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→2. Treatment trains designed to address one or more design criteria
===2. Treatment trains designed to address one or more design criteria===
===2. Treatment trains designed to address one or more design criteria===
[[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.
'''Example''': [[Pretreatment#Concentrated underground flow|Proprietary filtration treatment device]] (providing water quality) draining to an underground [[infiltration trench]] or [[Infiltration chambers|chamber system]] (providing water balance control). Overflows from the trench or chamber system could drain to a [[dry pond]] or other flood control facility to provide water quantity and erosion control). Another example may be to direct low flows from a stormwater management pond [[outlet]] to an infiltration practice.
'''Example''': [[Pretreatment#Concentrated underground flow|Proprietary filtration treatment device]] (providing water quality) draining to an underground [[infiltration trench]] or [[Infiltration chambers|chamber system]] (providing water balance control). Overflows from the trench or chamber system could drain to a [[dry pond]] or other flood control facility to provide water quantity and erosion control). Another example may be to direct low flows from a stormwater management pond [[Overflow|outlet]] to an infiltration practice.
'''Performance calculation''': Treatment trains designed to address multiple design criteria may improve overall water quality performance by, for example, reducing water quality concentrations in the first facility and reducing water quality loads (through infiltration/evapotranspiration) in a second facility. Even if the effluent concentration from facility one and facility two are the same, the overall load reduction of the treatment train may be greater than provided by any one of the facilities alone.
'''Performance calculation''': Treatment trains designed to address multiple design criteria may improve overall water quality performance by, for example, reducing water quality concentrations in the first facility and reducing water quality loads (through infiltration/evapotranspiration) in a second facility. Even if the effluent concentration from facility one and facility two are the same, the overall load reduction of the treatment train may be greater than provided by any one of the facilities alone.
===3. Treatment trains designed to enhance overall treatment system performance===
===3. Treatment trains designed to enhance overall treatment system performance===