Glossary

In this section you will find a list of commonly used acronyms that you may come across when learning about stormwater and sewage issues.

  • Green Infrastructure (GI) - refers to a decentralized network of site-specific stormwater management techniques that are implemented to reduce volume of stormwater runoff entering the sewer system while also restoring the natural hydrologic cycle (infiltration, storage, evapotranspiration).
  • Combined Sewer Overflows (CSOs) – sewers that are designed to collect rainwater runoff, domestic sewage and industrial wastewater in the same pipe. During heavy rain or a snowmelt, the wastewater volume in a combined sewer system can exceed the capacity of the sewer system or treatment plant. As a result, untreated combined sewage is discharged directly into water bodies, and can significantly impact downstream water quality.
  • Sanitary Sewer Overflows (SSOs) - occasional unintentional discharges of raw sewage from municipal sanitary sewers occur in almost every system.
  • Stormwater Best Management Practices (BMP) - Storm water best management practices are methods designed to control storm water runoff incorporating sediment control, and soil stabilization. They also define management practices that can prevent or reduce non-point source pollution. The EPA defines stormwater BMPs as a “technique, measure or structural control that is used for a given set of conditions to manage the quantity and improve the quality of storm water runoff in the most cost-effective manner.”
  • Low Impact Development (LID) - an approach to land development (or redevelopment) that works with nature to manage stormwater as close to its source as possible. LID employs principles such as preserving and recreating natural landscape features, minimizing effective imperviousness to create functional and appealing site drainage that treat stormwater as a resource rather than a waste product.
  • Infiltration - allowing water to slowly sink into the soil
  • Bioretention (Rain Gardens) - shallow surface depressions planted with specifically selected, native vegetation to treat and capture runoff and are sometimes underlain by a sand or gravel/storage/infiltration bed. Bioretention is a method of managing stormwater by pooling water within a planting area and then allowing the water to infiltrate the garden.
  • “Green” Roofs - a cover installed on top of conventional flat roofs giving the roofs characteristics that more closely resemble a natural environment. They can be optimized to achieve water quantity and water quality benefits.
  • Green Streets/Green Alleys - provides source control for stormwater, limits its transport and pollutant conveyance to the collection system, restores predevelopment hydrology to the extent possible, and provides environmentally enhanced roads.
  • Tree Trenches - in providing an increased tree canopy, tree trenches perform the same functions that other infiltration practices perform (infiltration, storage, evapotranspiration)
  • Pervious/Permeable Pavement - a technique that combines stormwater infiltration, storage, and structural pavement consisting of a permeable surface underlain by a storage/infiltration bed.
  • Rain/Cistern Barrels - structures designed to intercept and store runoff from rooftops to allow for its reuse, reducing volume and overall water quality impairment. Stormwater is contained in the cistern or rain barrel structure and typically reused for irrigation or other water needs.
  • Downspout Disconnection - the process of separating roof downspouts from the sewer system and redirecting roof runoff onto pervious surfaces
  • Triple Bottom Line Approach - sustainable practices define effectiveness in terms of financial, social and environmental benefits (as known as a “triple bottom line”). This approach bases project decisions on an analysis of the cost and benefits where there is a balance between the effects on the environment, a project’s financial commitments and the community where the project is located.
  • Clean Water Act - Enacted in 1948 and revised in 1972, the act defines the structures by which discharges into rivers are regulated. Under the act, the EPA has implemented pollution control programs (i.e. wastewater standards for industry) as well as water quality standards for all surface water.