*The flow path length across the vegetated filter strip should exceed the maximum flow path length across the impervious surface draining to it.
*The flow path length across the vegetated filter strip should exceed the maximum flow path length across the impervious surface draining to it.
*The filter strip should have a flow path length of ≥ 5 m; however, some pollutant removal benefits are realized ≥ 3 m.
*The filter strip should have a flow path length of ≥ 5 m; however, some pollutant removal benefits are realized ≥ 3 m.
−
*Should be graded to provide a 75 to 100 mm elevation drop between pavement edge or flush curb and filter strip surface to dissipate energy, promote settling and allow for accumulation of sediment and debris between cleanings.
+
*Should be graded to provide a 75 to 150 mm elevation drop between pavement edge or flush curb and filter strip surface to dissipate energy, promote settling and allow for accumulation of sediment and debris between cleanings.
===Pretreatment===
===Pretreatment===
*A [[level spreader]] or [[gravel diaphragm]] at the top of the slope is always recommended.
*A [[level spreader]] or [[gravel diaphragm]] at the top of the slope is always recommended.