This glossary contains terms you may run across on this site or in some other EHS context.
Off-Site Facility: A hazardous waste treatment, storage, or disposal area that is located at a place away from the generating site.
Oil Spill: An accidental or intentional oil discharge that reaches bodies of water. It may be controlled by chemical dispersion, combustion, mechanical containment, or adsorption. For more information, see the Oil Spills topic page.
On-Ground Tank: A hazardous waste storage tank that is situated in such a way that the bottom of the tank is on the same level as the adjacent surrounding surface so that the external tank bottom cannot be visually inspected. For more information, see the Hazardous Waste Tanks topic page.
On-Site Facility: A hazardous waste treatment, storage, or disposal area that is located on the generating site.
Open Burning: Uncontrolled fires in an open dump.
Organic: Containing carbon.
Overturn: The sinking of surface water and the rising of bottom water in a lake or sea that results from changes in temperature that occur in spring and fall wherever lakes are icebound in winter.
Particulates: Fine liquid or solid particles such as dust, smoke, mist, fumes, or smog found in air or emissions.
PCBs: A group of toxic, persistent chemicals (polychlorinated biphenyls) used in transformers and capacitors for insulating purposes and in gas pipeline systems as a lubricant. PCBs were banned by law for sale in 1974. For more information, see the PCB Management topic page.
Permeability: The degree to which liquid can pass through a substance or mass; 10-7 cm equals one inch per year; 10-6 cm equals one foot per year.
Persistent Bioaccumulative Toxics (PBT): Group of chemicals that are not only toxic, but remain in the environment for long periods, are not readily destroyed, and accumulate in body tissue.
Pesticide: Substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Also, any substance or mixture of substances intended for use as a plant regulator or defoliant. For more information, see the Pesticides topic page.
pH: A measure of the acidity or alkalinity of a solution on a scale of 0 to 14 (low is acid; high is alkaline or base; and 7 is neutral).
Physical and Chemical Treatment: Processes generally used in large wastewater treatment facilities. Physical processes may involve air stripping or filtration. Chemical treatment includes coagulation, chlorination, or ozone addition. The term may refer to treatment processes, treatment of toxic materials in surface water and groundwater, oil spills, and some methods of dealing with hazardous materials on or in the ground.
Pit: See Lagoon.
Placards: A color-coded, diamond-shaped sign that identifies by word or symbol the hazard associated with chemicals, including hazardous materials and hazardous wastes. Placards are required by the U.S. Department of Transportation to be placed on the end and sides of trucks, railcars, and portable tanks (such as aboveground tanks) when used to transport hazardous materials or hazardous wastes.
Plume: A visible or measurable discharge of contaminant from a given point of origin. Can be visible or thermal in water, or visible in the air (a plume of smoke).
Point Source: A stationary location or fixed facility from which pollutants are discharged or emitted. Also, any single identifiable source of pollution, such as a pipe, ditch, or ship.
Pollutant: Generally, any substance introduced into the environment that adversely affects the usefulness of the resource.
Pollution: Generally, the presence of matter or energy whose nature, location, or quantity produces undesired environmental effects. Under the Clean Water Act, for example, the term is defined as a man-made or man-induced alteration of the physical, biological, and radiological integrity of water.
Pollution Prevention: The active process of identifying areas, processes, and activities that create excessive waste by-products or pollutants for the purpose of substitution, alteration, or elimination of the process to prevent waste and pollutant generation. For more information, see the Pollution Prevention topic page.
Pond: See Lagoon.
Post-Closure: The time period following the shutdown of a waste management or manufacturing facility. For monitoring purposes, this is considered to be 30 years. For more information, see the Closure/Post-Closure Plans topic page.
Potentially Responsible Party (PRP): Any individual or company, including owners, operators, transporters or generators, potentially responsible for, or contributing to, the contamination problems at a Superfund site. Whenever possible, EPA requires PRPs, through administrative and legal actions, to clean up hazardous waste sites they have contaminated.
PPM/PPB: Parts per million/parts per billion, a way of expressing tiny concentrations of pollutants in air, water, soil, human tissue, food, or other products.
Pretreatment: Processes used to reduce, eliminate, or alter the nature of wastewater pollutants from nondomestic sources before they are discharged into publicly owned treatment works. For monitoring purposes, this is considered to be 30 years. For more information, see the Pretreatment Standards topic page.
Prevention of Significant Deterioration (PSD): EPA program in which state and/or federal permits are required that are intended to restrict emissions for new or modified sources in places where air quality is already better than required to meet primary and secondary ambient air quality standards.
Primary Waste Treatment: First steps in wastewater treatment. Screens and sedimentation tanks are used to remove most materials that float or will settle. For more information, see the Wastewater - General topic page.
Publicly Owned Treatment Works (POTW): A waste treatment works owned by a state, local government unit, or Indian tribe, usually designed to treat domestic wastewaters. For more information, see the Wastewater - General topic page.
Enviro Glossary Terms A
Enviro Glossary Terms B and C
Enviro Glossary Terms D and E
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Enviro Glossary Terms I through L
Enviro Glossary Terms M and N
Enviro Glossary Terms O and P
Enviro Glossary Terms Q and R
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