TrackOuts and BMP Glossary


Accelerated Erosion

Erosion caused or increased by human activity, such as agriculture or construction, as opposed to naturally occurring erosion.2


The deposition of sediment in a stream in a manner and extent that the bed elevation of the stream rises.3


Best Management Practice (BMP)

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.1 A series of water quality protection practices and procedures approved or certified by the State water quality agency under the provisions of sections 219 and 402 of the federal Clean Water Act, as amended.3


A soil and plant–based stormwater management best management practice (BMP) used to filter runoff.1


Catch Basin

An inlet to the storm drain system that typically includes a grate or curb inlet.1

Catch Basin Insert

Devices that attach to the entrance of a catch basin or mount inside the catch basin. They are designed to improve stormwater quality by either preventing debris and pollutants from entering the basin, or by retaining or treating the water in the basin.1

Check Dam

A structure, typically constructed of rock, sediment retention fiber rolls, gravel bags, sandbags, or other proprietary product, placed across a natural or man made channel or drainage ditch and design ed to reduce scour and channel erosion by reducing flow velocity and encouraging sedimentation.1

Compost Blanket

Consists of a layer of graded Compost spread over prepared, seeded topsoil to protect exposed soil against raindrop and wind erosion and to provide an organic soil amendment to promote the establishment of vegetation.3

Compost Filter Berms

Used on slopes in conjunction with compost blanket to reduce flow length and control rill and gully erosion.3


Structure or feature used for transferring water from one location to another.1

Concrete Washout Area

Shallow excavation with a small perimeter berm to isolate concrete truck washout operations.3


Improvements by a Contractor that may include excavating, site grading, utility work, paving, building, and other activities that may contribute to the disturbance of land and elevated levels of erosion and sediment.3

Construction Fence

Orange plastic fencing, or other approved material, attached to support posts and used to control access to the construction site and delineate limits of construction.3

Construction Markers

Consists of wooden lath or other markers, with tops painted orange, spaced at 100 foot centers to delineate limits of construction. Construction markers may be used as an alternative to construction fence if approved by the inspector.3

Culvert Inlet Filter

Reinforced rock berm placed in front of a culvert to reduce sediment in runoff approaching the culvert.3

Curb and Gutter System

Edging along the side of streets meant to quickly convey stormwater runoff from the street and adjacent areas into the stormwater system.1

Curb Sock

Small reinforced rock berm placed in the curb and gutter flowline in order to filter stormwater runoff, and reduce sediment from entering the storm sewer system.3



Erosion of bed material from the bottom of a stream leading to a lowering of the channel invert.3


Gravel filter provided on the suction end of a pump to reduce the pumping of sediment and a rip rap pad at the discharge end of the pump to provide erosion protection. Dewatering includes settling the discharge water in a small basin or sediment pond before releasing to receiving waters.3

Diversion Ditch

Small earth channel used to divert and convey runoff to a sediment basin, check dam, or drainageway. Depending on slope, the diversion swale may need to be lined with erosion control matting, plastic (for temporary installations only), or riprap.3



Process by which soil, rock, or other material is moved from one location to another, typically through the action of water, ice or wind. 1

  • Typical sediment control practices focus on the following. 1
  • Physical filtration of sediment by trapping soil particles as water passes through a silt fence, drop inlet screen, fiber roll, etc. 1
  • Settling processes, that allow sediment to fall out of flows that are slowed and temporarily impounded in ponds, traps, or in small pools created by berms, silt fencing, inlet protection dikes, check dams, and so on.1

Erosion Control

Efforts to prevent the wearing or washing away of the soil or land surface.1

Erosion Control Blanket

Natural or geotextile mat placed in areas susceptible to erosion to hold the soil in place until it can be permanently stabilized through vegetation or armoring.1



Land adjacent to a waterbody which is inundated when the discharge exceeds the conveyance capacity of the normal channel. Often defined in a regulatory sense as the extent of the 100–year flood.1

Flow Control

Controlling the rate and volume of water leaving a site.1


Extra storage space or small basin located near the inlet to settle out incoming sediments before water moves on into a pond or detention area.1


The vertical distance between the design water surface elevation and the elevation of the barrier which contains the water.2

Functional Components Approach

Where basic BMP components are selected and pieced together to achieve a desired outcome.1



Textile made from synthetic fibers, usually nonbiodegradable. Geotextiles can be woven or nonwoven and have varying degrees of porosity. They are used as moisture barriers, for separation or reinforcement of soils, for filtration, and for drainage.2


High Density Residential

High concentration of housing units in a specific area or on a specific property, typical of urban areas.1


Any number of BMPs designed to keep pollutants from entering the waste stream by maintaining clean conditions, including street sweeping, litter pick–up and animal clean–up.1

Hydraulic Mulching

Applying wood fiber mulch and often a mixture of seed, water, and fertilizer in one application help retain soil and moisture; also known as hydromulching.2


Method of seeding by mixing seed with water and fertilizer and then spraying the solution onto a seedbed.2


Science dealing with the properties, distribution, and circulation of water hydroperiod the length of time an area is inundated or saturated by water.1


Impervious Surface

Hard surface area, which either prevents or retards the entry of water into the soil. Common impervious surfaces include roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled surfaces).2


Flow of water from the land surface into the subsurface.1

Inlet Protection

Preservation of the integrity and protection from the erosion of the area where water enters into a treatment area usually by vegetation or armoring.1


Low Density Residential

Low concentration of housing units in a specific area or on a specific property, typical of rural areas.1

Low Impact Development

An approach to stormwater management that mimics a site’s natural hydrology as the landscape is developed. Using the LID approach, stormwater is managed on site and the rate and volume of predevelopment stormwater reaching receiving waters is unchanged. The calculation of predevelopment hydrology is based on native soil and vegetation.1


Maximum Water Capacity (MWC)

Terminology used in FLL guidelines for Maximum Media Water Retention (MMWR); the quantity of water held in a media at the maximum media density. This is a useful measure of the capacity of a media to hold water under drained conditions.1

Media Filters

Filtration of stormwater through a variety of different filtering materials whose purpose is to remove pollution from runoff.1

Medium Density Residential

Moderate concentration of housing units in a specific area or on a specific property, typical of suburban areas.1

Minimum Control Measures

Six required components of SWPPPs for MS4 communities. The six minimum control measures are public education/outreach; public participation/involvement; illicit discharge detection and elimination; construction site runoff control; post–construction site runoff control; and pollution prevention/ good housekeeping. 1


New Development (MIDS definition)

Any development that results in the conversion of land that is currently prairie, agriculture, forest, or meadow and has less than 15 percent impervious surface. Land that was previously developed, but now razed and vacant, will not be considered new development.1


Off-line System

A flow system where only stormwater runoff treated by a BMP enters the BMP, with remaining water bypassing the BMP. 1

On-lineS ystem

Systems where all stormwater runoff enters and flows through a BMP.1


Peak Flow Control

Controlling the timing and magnitude of the largest flow either leaving the site or flowing through the watershed utilizing stormwater management techniques to avoid flooding and damage downstream. Also known as  Peak Discharge.1

Perimeter Control

Activities or practices designed to contain sediments on a project site.1

Pollution Prevention Practices

Proactive activities and strategies instituted to avoid introducing pollution into the environment.1


Practices used to reduce, eliminate, or alter pollutants in stormwater, primarily sediment, before they are discharged into structural stormwater BMPs. Pretreatment practices include settling devices, screens, and pretreatment vegetated filter strips.1



Any construction, alteration, or improvement that disturbs greater than or equal to 5,000 square feet of existing impervious cover performed on sites where the existing land use is commercial, industrial, institutional, or residential.1

Redevelopment (MIDS definition)

Any development that is not considered new development. 1


Permanent or temporary storage of stormwater to prevent it from leaving the development site retrofit the introduction of a new or improved stormwater management element where it either never existed or did not operate effectively.1

Rill Erosion

An erosion process in which numerous small channels several inches deep are formed.1


Water originating from rainfall and other precipitation that is found in drainage facilities, rivers, streams, springs, seeps, ponds, lakes and wetlands as well as shallow ground water.2


Secondary Treatment

Biological and mechanical processes that remove dissolved or suspended material from wastewater.1


Fragmented material that originates from weathering and erosion of rocks or unconsolidated deposits, and is transported by, suspended in, or deposited by water.2

Sediment Control Basins

A designed depression in the landscape utilized to settle out sediments from the water column before discharge into other drainages.1

Sediment Removal

Removal, usually by settling or filtering, of suspended sediments from the water column.1

Sediment Yield

The amount of sediment removed from a watershed over a specified period of time.1

Separation Distance

The distance from the closest point of a Best Management Practice (BMP) to the particular feature being considered.1


Technique to remove sediment from wastewater by slowing the water flow velocity allowing the sediments to sink to the bottom.1

Sheet Erosion

The removal by surface runoff of a fairly uniform layer of soil from a bank slope.2


Runoff which flows over the ground surface as a thin, even layer, not concentrated in a channel. 2

Silt Curtain

A natural or synthetic fabric suspended by floats and weighted at the bottom which is stretched across a water feature and used to trap and retain sediments on site.1

Silt Fence

Fence constructed of wood or steel supports and either natural or synthetic fabric stretched across an area (non–concentrated flow) during site development to trap and retain on–site sediment due to rainfall runoff.1

Site Constraint

Conditions unique to the site that that serve to restrain, restrict, or prevent the implementation of proposed or desired design features.1

Soakaway Pit

Small, excavated pits, backfilled with aggregate, used to infiltrate good quality stormwater runoff, such as uncontaminated roof runoff.1

Soil Permeability

The ease with which gases, liquids, or plant roots penetrate or pass through a layer of soil.1


The use of measures such as rock lining, vegetation or other engineering structures to prevent the movement of soil when loads are applied to the soil. 2

Stabilized Staging Area

Stripping topsoil and spreading a layer of granular material in the area to be used for a trailer, parking, storage, unloading, and loading. A stabilized staging area reduces the likelihood that the vehicles most frequently entering a site are going to come in contact with mud. 3

Straw Wattles

Temporary erosion and sediment control barriers, tubular in shape, consisting of straw that is wrapped in biodegradable material.1


Water that is generated by rainfall or snowmelt which causes runoff and is often routed into drain systems for treatment or conveyance.1

Structural Stormwater BMP

Defined in the MS4 General permit as “a stationary and permanent BMP that is designed, constructed and operated to prevent or reduce the discharge of pollutants in stormwater”. For the purposes of the TMDL Annual Reporting form, a structural BMP refers specifically to a constructed basin, filter, infiltrator, swale or strip.1


Temporary Construction

Sediment control techniques practices employed on an active construction site to control movement of sediment within or off of the site until permanent vegetation or sediment controls can be established.1

Temporary Slope Drain

A small culvert or plastic lined channel to convey runoff down a slope or channel bank to reduce the occurrence of rill and gully erosion. (3)

Total Suspended Solids

The entire amount of organic and inorganic particles dispersed in water.2



Multi-family or mixed-use residential buildings with 50 or more dwelling units per acre, covering 75 percent or more of the lot, and parking is all or substantially all enclosed; or retail, office, civic or institutional buildings covering 75 percent or more of the lot and parking is all or substantially all enclosed.1


An underground drain or trench with openings through which the water may percolate from the soil or ground above.1

Vehicle Tracking BMP

A rock (stone or quarry spall) pad, often including a trackout control device designed to remove soil and mud from tires before the vehicle leaves the work zone and enters public roadways or parking lots.1


Wet Vault

A wet vault is a vault stormwater management device with a permanent water pool, generally 3 to 5 feet deep.1

Wind Erosion

Removal of soil particles by wind, causing dryness and deterioration of soil structure; occurs most frequently in flat, dry areas covered by sands and loamy soils.2

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