|
Glossary
Bioretention: Also known as Rain Garden, Bio-Filter and an LID BMP. On-lot retention of stormwater through the use of vegetated depressions engineered to collect, store, and infiltrate runoff.
BMP: Best Management Practice; a practice or combination of practices that are the most effective and practicable (including technological, economic, and institutional considerations) means of controlling point or nonpoint source pollutants at levels compatible with environmental quality goals.
Buffer: A vegetated zone adjacent to a stream, wetland, or shoreline where development is restricted or controlled to minimize the effects of development.
Cluster Development: Buildings concentrated in specific areas to minimize infrastructure and development costs while achieving the allowable density. This approach allows the preservation of natural open space for recreation, common open space, and preservation of environmentally sensitive features.
Curbs: Concrete barriers on the edges of streets used to direct stormwater runoff to an inlet or storm drain and to protect lawns and sidewalks from vehicles.
Design storm: A rainfall event of specific size, intensity, and return frequency (e.g.,. the 1-year storm) that is used to calculate runoff volume and peak discharge rate.
Detention: The temporary storage of stormwater to control discharge rates, allow for infiltration, and improve water quality.
Dissolved Oxygen (DO): Amount of oxygen dissolved in water. The DO is expressed in parts per million (ppm) or milligrams per liter (mg/L).
Dry Well: Small excavated trenches filled with stone to control and infiltrate rooftop runoff. EPA: Environmental Protection Agency. Erosion: The process of soil detachment and movement by the forces of water.
Fecal Coliform: Bacteria found only in the intestinal tracts of humans and animals. The major sources are animal waste, waste treatment plants, and failing septic systems. The presence of this bacteria typically indicates pollution that may pose a potential health risk.
Filter Strips: Bands of closely-growing vegetation, usually grass, planted between pollution sources and downstream receiving waterbodies.
Geographic Information System (GIS): A system for capturing, storing, checking, integrating, manipulating, analyzing and displaying geographically referenced data.
Greenway: A linear open space; a corridor composed of natural vegetation. Greenways can be used to create connected networks of open space that include traditional parks and natural areas.
Groundwater: Water stored underground in the pore spaces between soil particles or rock fractures.
Habitat: An area or type of area that supports plant or animal life.
Hydrology: The science dealing with the waters of the earth, their distribution on the surface and underground, and the cycle involving evaporation, precipitation, flow to the seas, etc.
Hypothesis: A statement that predicts what you think will happen.
IMP: Intregrated management practice. A LID practice or combination of practices that are the most effective and practicable (including technological, economic, and institutional considerations) means of controlling the predevelopment site hydrology.
Impervious Area: A hard surface area (e.g., parking lot or rooftop) that prevents or retards the entry of water into the soil, thus causing water to run off the surface in greater quantities and at an increased rate of flow.
Imperviousness Overlay Zoning: One form of the overlay zoning process. Environmental aspects of future imperviousness are estimated based on the future zoning build-out conditions. Estimated impacts are compared with watershed protection goals to determine the limit for total impervious surfaces in the watershed. Imperviousness overlay zoning areas are then used to define subdivision layout options that conform to the total imperviousness limit.
Incentive Zoning: Zoning that provides for give-and-take compromise on zoning restrictions, allowing for more flexibility to provide environmental protection. Incentive zoning allows a developer to exceed a zoning ordinances limitations if the developer agrees to fulfill conditions specified in the ordinance. The developer may be allowed greater lot yields by a specified amount in exchange for providing open spaces within the development. Infiltration: The downward movement of water from the land surface into the soil.
Level Spreader: An outlet designed to convert concentrated runoff to sheet flow and disperse it uniformly across a slope to prevent erosion.
Low Impact Development: The integration of site ecological and environmental goal and requirements into all phases of urban planning and design from the individual residential lot level to the entire watershed.
Macroinvertebrate: An organism that lacks a backbone and is visible without magnification. Examples include snails, worms, fly larvae, and crayfish ("crawdads").
Nonpoint Source Pollution: Water pollution caused by rainfall or snowmelt moving both over and through the ground and carrying with it a variety of pollutants associated with human land uses. A nonpoint source is any source of water pollution that does not meet the legal definition of point source in section 502(14) of the Federal Clean Water Act.
NPDES: National Pollutant Discharge Elimination System; a regulatory program in the Federal Clean Water Act that prohibits the discharge of pollutants into surface waters of the United States without a permit.
Open Space: Land set aside for public or private use within a development that is not built upon.
Overlay Districts: Zoning districts in which additional regulatory standards are superimposed on existing zoning. Overlay districts provide a method of placing special restrictions in addition to those required by basic zoning ordinances.
Particulates: Small pieces of material floating in water.
Permeable: Soil or other material that allows the infiltration or passage of water or other liquids.
pH: Measures the Hydrogen (H+) ion concentration of a substance. It is based on a scale that ranges from 0 (most acidic) to 14 (most basic). A pH of 7 is considered neutral. Each unit of change represents a tenfold change in acidity or alkalinity.
Planned Unit Development (PUD) Zoning: Planned unit development provisions allow land to be developed in a manner that does not conform with existing requirements of any of the standard zoning districts. The PUD allows greater flexibility and innovation than conventional standards because a planned unit is regulated as one unit instead of each lot being regulated separately.
Rain Barrels: Barrels designed to collect and store rooftop runoff. Recharge Area: A land area in which surface water infiltrates the soil and reaches the zone of saturation or groundwater table.
Rain Garden: See bioretention. Synonymous with bioretention, this term is typically used for general audience discussions.
Riparian Area: Vegetated ecosystems along a waterbody through which energy, materials, and water pass. Riparian areas characteristically have a high water table and are subject to periodic flooding.
Runoff: Water from rain, melted snow, or irrigation that flows over the land surface.
Scientific Method: A systematic approach involving recognition of a problem, formulation of a hypothesis, development of an experiment, observation and analysis of the results, and a conclusion that may reject or accept the hypothesis. More...
SCS: U.S. Department of Agriculture Soil Conservation Service; renamed the Natural Resources Conservation Service (NRCS).
Sediment Control Device: A protection device used to cover a drainage inlet during the course of construction to prevent sediment and debris from entering the drainage system.
Site Fingerprinting: Development approach that places development away from environmentally sensitive areas (wetlands, steep slopes, etc.), future open spaces, tree save areas, future restoration areas, and temporary and permanent vegetative forest buffer zones. Ground disturbance is confined to areas where structures, roads, and rights-of-way will exist after construction is complete.
Subdivision: The process of dividing parcels of land into smaller building units, roads, open spaces, and utilities.
Swale: An open drainage channel designed to detain or infiltrate stormwater runoff.
Turbidity: Measures the clarity of water. High turbidity results when there are a lot of particulates floating around and the water is cloudy. Low turbidity results when there are few floating particulates and the water is clear.
Underdrain: A perforated pipe, typically 4-6" in diameter placed longitudinally at the invert of a bioretention facility for the purposes of achieving a desired discharge rate.
Urbanization: Changing land use from rural characteristics to urban (city-like) characteristics.
Urban Sprawl: Development patterns, where rural land is converted to urban uses more quickly than needed to house new residents and support new businesses. As a result people become more dependent on automobiles and have to commute farther. Sprawl defines patterns of urban growth that include large acreage of low-density residential development, rigid separation between residential and commercial uses, residential and commercial development in rural areas away from urban centers, minimal support for nonmotorized transportation methods, and a lack of integrated transportation and land use planning.
USGS: United States Geological Survey, an agency within the Department of the Interior.
Watershed: The topographic boundary within which water drains into a particular river, stream, wetland, or body of water.
Watershed-based Zoning: Zoning that achieves watershed protection goals by creating a watershed development plan, using zoning as the basis (flexible density and subdivision layout specifications), that falls within the range of density and imperviousness allowable for the watershed to prevent environmental impacts. Watershed-based zoning usually employs a mixture of zoning practices.
Wet pond: A stormwater management pond designed to detain urban runoff and always contain water. Zero-lot-line Development: A development option in which side yard restrictions are reduced and the building abuts a side lot line. Overall unit-lot densities are therefore increased. Zero-lot-line development can result in increased protection of natural resources, as well as reduction in requirements for road and sidewalk.
Zoning: Establishes minimum criteria to be used when assessing whether a particular project is appropriate for a certain area; ensures that the end result adheres to an acceptable level of performance or compatibility. Regulations or requirements that govern the use, placement, spacing, and size of land and buildings within a specific area.
return to top
| 
