BMP - Best Management Practice: one of many different structural or non–structural methods used to treat runoff, including such diverse measures as ponding, street sweeping, filtration through a rain garden and infiltration to a gravel trench.
Forebay - An artificial pool or reservoir that slows/temporarily detains flow to allow sediments and other solids to settle out. (Synonyms; sediment forebay, sediment pool, small sediment basin, impoundment, basin, storage structure, excavated pit, upfront settling basin).
Grass swale - A vegetated channel that conveys stormwater while allowing for settling of sediments and debris (Synonyms; Vegetated waterway, grass channel, drainage ditch).
Grease - Oil based pollutant.
Grit - Coarse sediments such as smaller, loose particles of sand and stone or other heavy solid materials that have specific gravities or setting velocities substantially greater than those of organic particles.
Media filter - Filtration of stormwater through a variety of different filtering materials whose purpose is to remove pollution from runoff.
Multiple chambers - A design consisting of several, separate structures (manholes, catch basins, tanks, chambers, etc.) intended to increase pollutant removal, treat higher flow rates, or both.
Non-proprietary Settling Device - System that is installed in stormwater sewers and that utilizes a sump to settle out sediment and other solids while also providing protection to the outlet to contain floatables, oil and grit. (Synonyms; standard sump manhole, water quality inlet, deep sump catch basins, modified catch basins).
Off-line - Installation in which flow is diverted from the main stormwater sewer system into a device, but diverted flow is limited so that devices are not flushed during large storm events.
Orifice - An opening structure found in forebay designs to control flow rates.
Proprietary devices - Devices that are privately developed and owned.
Proprietary settling device - Privately developed systems that utilize a variety of mechanisms to settle out sediments and solids. The devices are installed along stormwater sewer systems and can contain multiple chambers and use more advanced technology than non-proprietary settling devices. (Synonyms; flow through structures, vortex separator systems).
Rhizosphere - The region of soil in the vicinity of plant roots in which the chemistry and microbiology is influenced by their growth, respiration, and nutrient exchange.
Screening - The process of removing sediments and solids from flowing stormwater via a screen. (Synonyms; Filtering)
Scum - A dirt or froth layer on the water surface.
Settling - The process of removing sediments and solids by slowing the velocity of flow to allow the pollutants to settle out of the water column.
Solids - Particulate pollutants consisting of sediments, debris and/or trash.
Stormwater hotspot - Activities or practices that produce relatively high levels of often specific stormwater pollutants.
Structural best management practice - A stationary and permanent BMP that is designed, constructed and operated to prevent or reduce the discharge of pollutants in stormwater.
Vegetated filter strip - Vegetated slopes that convey stormwater as sheet flow to allow settling of sediments and solids. (Synonyms; vegetated buffer, vegetated buffer strip, grassed filter strips, grass filters).
Vortex separator systems - A mechanism used in many proprietary settling devices that uses the circular flow within a chamber to separate solids from the stormwater. (Synonyms; swirl separators, hydrodynamic separators, swirl concentrators, flow through structures).
Weir - A flow or water level control device, often consisting of a thin plate (sharp-crested).