A Glossary of Green Infrastructure Terms and Concepts
The following is adapted from two key texts: NYC Green Infrastructure Techniques, published by GrowNYC, a hands-on non-profit which improves New York City’s quality of life through environmental programs, and High Performance Infrastructure Guidelines, by Hillary Brown et al, published by the New York City Department of Design and Construction (NYC DDC).
See our Publications page for links to view these and many other documents.
Go to the list of commonly used acronyms here or find them at the bottom of the page
Bioswale
A linear, sloped retention area designed to capture and convey water, while allowing
it to infiltrate into the ground slowly over a 24 to 48 hour period.
Combined sewer
Sewers that are designed to collect water runoff from rainfall, domestic sewage, and industrial waste water in the same pipe.
Combined Sewer Overflow
During rain events storm water enters the sewer system and causes the system to exceed its intended capacity. In New York City wastewater treatment plants rain events will cause all of the water to be directed to the waterways around the city creating what are called Combined Sewer Overflows or CSOs.
French Drain
A ditch lined with rocks, gravel, or a perforated pipe that redirects surface and groundwater towards or away from an area. For a diagram, see above under Bioswale.
Green infrastructure
According to the US Environmental Protection Agency, green stormwater infrastructure includes a wide array of practices at multiple scales that manage wet weather and that maintain and restore natural hydrology by infiltrating, evapotranspiring and harvesting and using stormwater. On a regional scale, green infrastructure is the preservation and restoration of natural landscape features, such as forests, floodplains and wetlands, coupled with policies, such as infill and redevelopment that reduce overall imperviousness in a watershed.
On the local scale, green infrastructure consists of site- and neighborhood-specific practices, such as bioretention, trees, green roofs, permeable pavements and cisterns. Green infrastructure practices treat rainwater as a valuable resource to be harvested and used on site, or filtered and allowed to soak back into the ground, recharging our aquifers, rivers and streams. The plants used in green infrastructure help to cool our surroundings and improve air quality through the process of evapotranspiration. These green practices can also help beautify our streets and neighborhoods, improve property values, revitalize downtowns and improve the overall quality of our lives.
Groundwater recharge
Movement of water out of an area of saturated soil. In well drained soils rainwater seeps into the ground and moves downwards through the soil until it reaches the water table. On the Lower East Side, the water table is comparatively close to the surface of our streets and gardens. New York City makes very little use of its natural groundwater, but recharging aquifers can reduce saltwater incursion.
Impervious
The opposite of permeable, impervious surfaces like parking lots or sidewalks block water, rather than allow it to pass through to the ground. New York City DEP is adopting “green infrastructure” techniques to convert 2% of currently impervious surfaces citywide by 2016, expanding to 10% citywide by 2030.
Infiltration
The process by which water landing on the surface of the ground enters the soil. Rates of infiltration are dependent upon soil conditions, which vary in Lower East Side community gardens. Many gardens have been reclaimed from building foundations, so before any green infrastructure improvement is undertaken, Gardens Rising will conduct detailed geo-tech research.
Infrastructure
Planners and public officials use the word “infrastructure” to describe the complex system of energy and materials that flow through the city on a daily basis. Infrastructure components include the roads, sidewalks, and sub-grade utility systems, as well as landscaped areas, and the interplay of these components profoundly affects our experience of the city.
By supporting community-coordinated, sustainable approaches to infrastructure design, construction, operations, and maintenance, Gardens Rising works to promote safety, public health, and quality of life.
Mitigate
To make changes or improvements in order to alleviate or lessen the severity of a problem or issue. Gardens Rising proposes using green infrastructure techniques to mitigate environmental damage from stormwater.
Percolation
The slow movement of water through the pores in soil or permeable rock.
Perforated pipe
A pipe with holes along the pipe walls designed to helps ease soggy
yards, flooded fields and wet basements by dispersing water evenly.
Permeable
Allows liquids or gas to pass through.
Permeable Pavement
Unlike traditional concrete sidewalks and asphalt parking lots, a permeable pavement is designed to let rainfall pass through the surface, reducing stormwater runoff from a site. Given appropriate soil and subsurface conditions, permeable pavements can be used in any type of development, for example: roads, parking lots, sidewalks, basketball and tennis courts, playgrounds, and plaza surfaces.
Rain Garden
A garden of native shrubs, perennials, and grasses which can withstand
both drought and occasional flooding. A rain garden is designed to hold rain water and runoff from adjacent roofs, driveways, patios or lawns, enabling water to infiltrate below ground level. The rain garden is dry most of the time and typically holds water for 24 hours or less following a rainfall event.
Right of Way (ROW)
Choreographing the complex circulation of automobiles, buses, bicycles, and pedestrians, New York City’s streets and sidewalks are shared public real estate for the social and economic activity that enriches civic life. Streets, sidewalks, and the complex infrastructure underlying them, are sometimes collectively referred to as the “Right of Way.” Projects involving the ROW fall under the jurisdictions and control of a number of different city agencies.
Street Trees
A New York City tree must battle many urban hazards daily — from air pollution and bicycles to dogs and people. In addition to above ground threats, in urban settings tree roots also must contend with tough below–ground conditions. A tree pit or lawn strip provides limited space, and this soil is a tree’s only source of nutrients.
As part of a green infrastructure program, enhancing or enlarging tree pits can improve the look and feel of the streetscape, improve the soil’s ability to absorb water, and improve the health of urban trees. Healthy trees offer a range of benefits: reducing energy usage by shading buildings in the summer and blocking winter winds; providing wildlife habitat; sequestering carbon dioxide and other greenhouse gases; intercepting and absorbing pollutants through their leaves and branches; and engaging residents in creating safer neighborhoods.
Street Trees in New York City are cared for by the Parks Dept. under the Million Trees initiative. Click the image to find out more.
Storm sewer
A sewer for carrying off rainfall drained from paved surfaces, roofs, and other
places that don’t absorb water. In the Lower East Side, storm water is mixed with waste water in a single combined sewer system.
Stormwater management
Anything associated with the planning, maintenance, and regulation of facilities which collect, store or convey stormwater.
Transpiration
Process by which water absorbed by plants, usually through the roots, evaporates into the atmosphere. Transpiration contributes to the redirection of water that would otherwise enter the combined sewer system.
Water Retention Capacity
The ability of a particular type of soil to hold water against the force of gravity. Different types of soils have difference capacities.
Acronyms of Agencies and Authorities
DCP
New York City Department of City Planning
DEP
New York City Department of Environmental Protection
DOB
New York City Department of Buildings
EPA
US Environmental Protection Agency
GOSR
Governor’s Office of Storm Recovery
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