Glossary

  • Aquifer – water-bearing geological formation that will yield water to a well or spring; aquifers can be classified as confined or unconfined.
  • Basin – surface area that drains into a surface water system.
  • BMP (Best Management Practice) – Stormwater BMPs are control measures taken to mitigate changes to both quantity and quality of urban runoff caused through changes to land use. Generally BMPs focus on water quality problems caused by increased impervious surfaces from land development. BMPs are designed to reduce stormwater volume, peak flows, and/or nonpoint source pollution through evapotranspiration, infiltration, detention, and filtration or biological and chemical actions. Stormwater BMPs can be classified as “structural” (devices installed or constructed on a site) or “non-structural” (procedures, such as modified landcaping practices).
  • Chlorinated Benzene – appearing in liquid and solid forms (crystalline) chlorinated benzenes impact soil, groundwater and sediment when released in large volumes and have the potential to persist in the environment when in solid form. These are a specific group of VOC contaminants.
  • Chlorinated Pesticides (DDT, Chlordane, Dieldrin) – This class of pesticides is bioaccumulative in the body, persistent in the environment and has the use has been banned in the US
  • Toxaphene– used as insecticide this complex compound is classed as a PBT due to its ability to persist even after long-distance transport
  • Contaminant – any element, substance, compound, mixture, or agent, other than a hazardous substance, which, after release from a facility and upon exposure of, ingestion, inhalation, or assimilation into any organism, wither directly from the environment or indirectly by ingestion, inhalation, or assimilation into any organism, either directly from the environment or indirectly by ingestion through food chains, will or may reasonably be anticipated to cause death, behavioral abnormalities, or other negative impacts.
  • CSO (Combined Sewer Overflow) – Combined sewer systems are sewers that are designed to collect rainwater runoff, domestic sewage, and industrial wastewater in the same pipe. Most of the time, combined sewer systems transport all of their wastewater to a sewage treatment plant, where it is treated and then discharged to a water body. During periods of heavy rainfall or snowmelt, however, the wastewater volume in a combined sewer system can exceed the capacity of the sewer system or treatment plant. For this reason, combined sewer systems are designed to overflow occasionally and discharge excess wastewater directly to nearby streams, rivers, or other water bodies.These overflows, called combined sewer overflows (CSOs), contain not only stormwater but also untreated human and industrial waste, toxic materials, and debris.
  • Dioxins Furans – This is a class of unintended by-product contaminants that are produced when products like herbicides are produced or when items are heated or burned. Dioxins and Furans are PBTs that are found in the air, soil and sediment.
  • Eutrophication – enrichment of natural waters with inorganic material, especially nitrogen and phosphorus, such that they support excessive growth of plants/algae.
  • Ground waters – water beneath the Earth’s surface at varying depths in reservoirs called aquifers.
  • Hazardous Waste – any waste material that is potentially dangerous, including explosives, radioactive materials, and chemicals.
  • Metals – Metals exist naturally in the environment in low to moderate concentrations and often bound in rocks or in soil or dissolved in surface or groundwater. Metals can be found as part of the natural environment but often sources of metals releasing to the environment in high concentrations create environmental risk. Concentrated metals not in equilibrium within the environment they are found can pose significant health risk to humans and biota if they accumulate. Mercury is a metal that transform to bioaccumulative and toxic methyl mercury through a biological process while in bodies of water. Arsenic and Zinc are metals that have potential toxic effects through exposure in soil, groundwater or sediment in elevated concentrations. Arsenic is persistent in the environment.
  • Nonpoint Source Pollution – Pollution of surface or ground-water supplies originating from land-use activities and/or the atmosphere, having no well-defined point of energy.
  • NPDES – National Pollutant Discharge Elimination System
  • PCBs (Polychlorinated Bi-Phenyls) – are a man-made organic chemical used in various electrical and heat resistant applications between 1929 to when their production was banned in 1979 in the U.S. PCBs exist in the environment in air, water, soil and sediment. Due to their pervasive, bioaccumulative and toxic nature they do not easily break down in the environment and require special management when they are remediated. This class of contaminants has been shown to have toxic as well as chronic effects on organisms exposed to them.
  • Pesticides (Insecticides) – Pesticides have been historically used across Delaware as part of agricultural and landscaping activities to prevent, destroy, repel or mitigate a pest. Whether applied properly, improperly or inadvertently released to the environment, pesticides can have detrimental health effects at high concentrations. This class of contaminants can be found in soil, sediment, ground water and surface water. Different pesticides have different fates once in the environment and are addressed based upon the specific compound.
  • Point source Pollution – pollution of surface or ground water supplies at well-defined, usually manufactured points or locations; eg. discharges of treated wastewater from municipal and industrial treatment plants.
  • PCS (Pollution Control Strategy) – includes a combination of more than one pollution-reducing method and is tailored specifically for each watershed. Methods could include: The removal of direct point-source discharges from waterways, better management of fertilizer and manure, replacement of failing septic systems with environmentally safer sewer systems, protective agricultural practices such as the planting of vegetative buffer strips between cropland and waterways, expanded levels of treatment of residential stormwater through the use of best management practices.
  • Septic system – on-site system designed to treat and dispose of domestic sewage. A typical sewage system consists of a tank that receives wastes from a residence or business and a system of tile lines or a pit for disposal of the liquid effluent remains after decomposition of the solids by bacteria in the tank.
  • Surface waters – lakes, ponds, streams, rivers, and other water bodies, which lie on the surface of the land; may be partially or fully supplies by ground water.
  • SVOCS (Semi-Volatile Organic Compounds) – are organic compounds which have a boiling point higher than water and which may vaporize when exposed elevated temperatures. They are often associated with petroleum based compounds and are similar to VOCs except for their lower volatility. They are not typically found in surface waters or sediments unless they are found in extremely high concentrations. While they do pose a risk to health, they are not pervasive, bioaccumulative and toxic.
  • TAT (Tributary Action Team) – citizens, farmers, educators, landowners, scientists and elected officials involved in sorting out the difficult issues, wrestling with the trade-offs, and developing ways to reduce pollution; we hope paths forward will have greater support in the communities they affect. The Tributary Action Team concept is an exciting opportunity for everyone in Delaware to make a big difference in the health of the environment.
  • TMDL (Total Maximum Daily Load) – calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards, an allocation of that amount to the pollutant’s sources.
  • Turbidity – measure of the amount of fine particles of solid matter suspended water.
  • VOCs (Volatile Organic Compounds) – are organic compounds whose composition makes it possible for them to evaporate under normal atmospheric conditions of temperature and pressure when exposed to the air. Often associated with paints, lacquers and cleaning supplies, VOCs are found in soils and groundwater where there has been a release to the environment. Due to the volatility of these compounds they are not typically found in surface waters or sediments unless found in extremely high concentrations. While they do pose a risk to health, they are not pervasive, bioaccumulative or toxic.
  • Watershed – area of land that contributes runoff to one specific delivery point; large watersheds may be composed of several smaller “sub-watersheds,” each of which contributes runoff to different locations that ultimately combine at a common delivery point.
  • Water Table – upper level of a saturated zone below the soil surface, often the upper boundary of a water-table aquifer.