Filtering Practices
Filtering practices push the water quality volume through an engineered medium — sand, organic matter or a planted soil bed — and collect the treated flow in an underdrain. The family spans surface, underground and perimeter sand filters, organic filters and bioretention cells. Filters are the specialists for small, intensely impervious drainage areas: parking lots, commercial frontage, ultra-urban corners where a pond could never fit, and stormwater hotspots where infiltration is off the table. Sediment removal is excellent and phosphorus removal solid; soluble nitrogen can pass through or even export, which the database rows for this group document honestly. Bioretention doubles as landscaping and has become the default practice of green streetscapes. The price of the small footprint is maintenance intensity — filter surfaces load up and need raking and media replacement on a schedule, not on hope. These sheets cover head requirements, Darcy sizing, media specifications and variant selection.
Filter Strip
Filter strips treat runoff as sheet flow across a band of dense vegetation, most often as pretreatment. Covers applicability, design criteria, performance and maintenance.
Filtering PracticesBioretention
Bioretention areas filter runoff through a planted soil bed, combining treatment with landscaping. Covers applicability, design criteria, monitored removal and maintenance.
Filtering PracticesSand Filter
Sand filters treat runoff by settling solids in a pretreatment chamber and filtering it through a sand bed. Covers design variants, criteria, performance and maintenance.
Filtering PracticesWater Quality Inlet
Water quality inlets are underground three-chamber vaults that trap grit and oil from small paved areas. Covers chamber design, sizing, performance limits and cleanouts.
Filtering Practices