| Term | Definition |
|---|
| Constructed Wetland | an engineered system designed to simulate natural wetland functions for water purification; essentially treatment systems that remove contaminants from wastewaters. |
| Impervious Surface | promotes runoff of precipitation volumes instead of infiltration into the subsurface; the imperviousness or degree of runoff potential can be estimated for different surface materials. |
| remediation | the process of cleaning up a contaminated site by physical, chemical, or biological means; typically applied to contaminated soil and groundwater. |
| site assessment | an evaluation of above-ground (including facilities) and subsurface characteristics, including the geology and hydrology of the site, to determine if a release has occured, as well as the extent and concentration of the release; information generated is used to support remedial action decisions. |
| stormwater runoff | consists of water volumes that are created during precipitation events and flow over surfaces into sewer systems or receiving waters; all precipitation waters that leave project site boundaries on the surface are considered. |
| total phosphorus (TP) | consists of organically bound phosphates, poly-phosphates, and orthophosphates in stormwater, the majority of which originates from fertilizer application; chemical precipitation is the typical removal mechanism. |
| total suspended solids (TSP) | particles or flocs that are too small or light to be removed from stormwater via gravity settling; typically removed via filtration. |
| infiltration basins and trenches | devices used to encourage subsurface infiltration of runoff volumes through temporary surface storage; pretreatment to remove sediment and oil may be necessary to avoid clogging. |
| basins | ponds that can store large volumes of stormwater; they need to drain within 72 hours to maintain aerobic conditions and to be available for the next storm event. |
| trenches | shallower and function as a subsurface reservoir for stormwater volumes. |
| porous pavement and permeable surfaces | used to create permeable surfaces that allow runoff to infiltrate into the subsurface; these surfaces are typically maintained wiht a vacuuming regime to avoid potential clogging and failure problems. |
| vegetated filter strips | utilize vegetation to filter sediment and pollutants from stormwater; appropriate for treating low-velocity surface sheet flows in areas where runoff is not concentrated; often used as pretreatment for other stormwater measures. |
| grassed swales | consist of a trench of ditch with vegetation and require occasional mowing; also encourage subsurface infiltration. |
| filtration basins | remove sediment and pollutants from stormwater runoff using a filter media such as sand or gravel; a sediment trap is usually included to remove sediment from stormwater before filtering to avoid clogging. |
| constructed wetlands | engineered systems that are designed to mimic natural wetland treatment properties; advanced designs incorporate a wide variety of wetland trees, shrubs, and plants while basic systems only include a limited number of vegetation types. |
| detention ponds | capture stormwater runoff and allow pollutants to drop out before release to a stormwater or water body; a variety are available with some utilizing only gravity while others use mechanical equipment such as pipes and pumps to facilitate transport; some are dry except during storm events; others permanently store water volumes. |
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