Changes

==Provide Runoff Pretreatment==

==Provide Runoff Pretreatment==

To treat runoff from highly trafficked pavements with LID practices it is wise to include [[Pretreatment| pretreatment]] features or components that capture and isolate sediment from the rest of the facility in the design. [[Pretreatment]] refers to techniques or devices used to retain coarse materials suspended in stormwater runoff, either through filtration or settling, before it enters the BMP rendering it inefficient over time. Proper pretreatment extends the operating phase of the BMP’s life cycle by reducing the rate of accumulation of coarse sediment, thus delaying the need for at times expensive structural repairs like unclogging filter beds, pipes and orifices. Common pretreatment devices include [[vegetated filter strips]], [[Enhanced swales|grass swales]], [[geotextile]]-lined inlet filters/liners, [[check dams]], [[forebays]], eavestrough screens or filters, [[Oil and grit separators| oil and grit separators]] (i.e., hydrodynamic separators) and catch basins or manholes containing baffles, filters and sumps. One important consideration for pretreatment is that these devices require frequent (e.g., annual) sediment and trash removal maintenance and should be easy to access by personnel, vehicles and equipment needed to perform inspection and maintenance tasks.

To treat runoff from highly trafficked pavements with LID practices it is wise to include [[Pretreatment| pretreatment]] features or components that capture and isolate sediment from the rest of the facility in the design. [[Pretreatment]] refers to techniques or devices used to retain coarse materials suspended in stormwater runoff, either through filtration or settling, before it enters the BMP rendering it inefficient over time. Proper pretreatment extends the operating phase of the BMP’s life cycle by reducing the rate of accumulation of coarse sediment, thus delaying the need for at times expensive structural repairs like unclogging filter beds, pipes and orifices. Common pretreatment devices include [[vegetated filter strips]], [[Enhanced swales|grass swales]], [[geotextile]]-lined inlet filters/liners, [[check dams]], [[forebays]], eavestrough screens or filters, [[Oil and grit separators| oil and grit separators]] (i.e., hydrodynamic separators) and catch basins or manholes containing baffles, filters and sumps. One important consideration for pretreatment is that these devices require frequent (e.g., annual) sediment and trash removal maintenance and should be easy to access by personnel, vehicles and equipment needed to perform inspection and maintenance tasks. From an operation and maintenance perspective, a good strategy is to select or design pretreatment features or components that existing programs already have capacity to maintain (e.g., catch basin and maintenance hole sumps).

[[File:Oil-grit separator USGS 2002.png|thumb|350px|Example oil-grit separator USGS 2002 (Wikimedia commons)]]

[[File:Oil-grit separator USGS 2002.png|thumb|350px|Example oil-grit separator USGS 2002 (Wikimedia commons)]]