Category: Environment Dictionary

Release: A release occurs when a hazardous substance goes from a controlled condition (for example, inside a truck, barrel, storage tank, or landfill) to an uncontrolled condition in the air, water, or land.

Recycling: The process by which salvaged materials become usable products. Specifically, the reuse of specific consumer or industrial items in order to conserve scarce materials, reduce pollution and littering and generally improve the condition of the environment.

Record of Decision (ROD): A legal document that announces and explains the cleanup methods ADEQ will use at a Superfund/WQARF site. The ROD is based on information and technical analysis generated during the remedial investigation and feasibility study, and in consideration of comments received during the public comment record for the proposed remedial action plan.

Reclaimed Water: Former wastewater that is treated to remove solids and impurities in compliance with standards in regulation, which may then be used for agriculture, landscape irrigation, recharge of groundwater aquifers, and power generation supplies, industrial and other uses.

Recharge: The process by which water is added to a zone of saturation, usually by percolation from the soil surface, like the recharge to an aquifer.

Reasonably Available Control Technology (RACT): Control technology that is reasonably available, and both technologically and economically feasible. Usually applied to existing sources in nonattainment areas; in most cases is less stringent than new source performance standards.

Radon: A common radioactive gas emitted from ordinary soils and rock. Radon has no smell, taste or color and can seep into homes, building up to dangerous levels if there is not enough ventilation. Exposure to high levels of radon gas over a long period of time increases the risk of developing lung cancer.

Radionuclide: Radioactive particle, man-made (anthropogenic) or natural, with a distinct atomic weight number. Radionuclides can have a long life as a soil or water pollutant.

Radioactive Waste: Any waste that emits energy as rays, waves, streams or energetic particles. Radioactive materials are often mixed with hazardous waste from nuclear reactors, research institutions, or hospitals.

Pump and Treat: A common method for cleaning up groundwater using pumps to bring polluted groundwater to the surface where it can be treated by various methods.

Public Water System (PWS): Refers to water systems which provide water to at least 15 service connections used by year-round residents or which provide water to at least 25 year-round residents, thus falling under the drinking water safety requirements of the federal Safe Drinking Water Act.

Public Comment Period: A period during which the public can formally review and comment on various documents and ADEQ actions.

Production Well: A well specifically designed to pump groundwater for domestic or municipal use (to differentiate from a monitoring well).

Procuraduría Federal de Protección al Ambiente (PROFEPA): Attorney General for Environmental Protection. A federal agency in Mexico that is responsible for inspections, compliance, and enforcement actions for environmental and natural resources protection.

Procuraduría Ambiental del Estado de Sonora (PROAES): State of Sonora Attorney General for the Environment. A separate agency in Sonora that conducts inspections and enforcement actions applied to air and waste regulatory requirements.

Primary Treatment: The removal of particulate materials from domestic wastewater, usually done by allowing the solid materials to settle as a result of gravity.

Prevention of significant deterioration (PSD): A construction air pollution permitting program designed to ensure air quality does not degrade beyond the national ambient air quality standard levels or beyond specified incremental amounts above a baseline level. It also ensures that the best available control technology is applied to major stationary sources and major modifications for regulated pollutants, and consideration of soils, vegetation and visibility in the permitting process.

Preliminary Investigation: Refers to the process of collecting and reviewing available information about a known or suspected hazardous waste site or release.

Potentially Responsible Party (PRP): A party (individual, corporation) identified by state or federal authorities as potentially liable for cleanup costs at a contaminated site.

Potable: Water of sufficient quality to serve as drinking water

Portable Particulate Monitor (PPM): A network of monitors across Arizona operated by ADEQ that record hourly average concentrations of Particulate Matter-2.5. The monitors can be deployed to measure PM-2.5 levels generated by wildfires and prescribed burns.

Polychlorinated Biphenyl (PCB): A group of toxic, persistent chemicals that once were used in high voltage electrical transformers because they conducted heat well while being fire resistant and good electrical insulators. These contaminants are typically generated from metal degreasing, printed circuit board cleaning, gasoline, and wood preserving processes

Pollution Prevention (P2): A national policy created by the Pollution Prevention Act of 1990 to have pollution prevented or reduced at the source wherever possible and also expand the Toxics Release Inventory. The Pollution Prevention Act focused industry, government, and public attention on reducing the amount of pollution through cost-effective changes in production, operation, and raw materials use

Point Source: Refers to a specific, identifiable source from which waste or pollution is released into the environment.

Plume: A well-defined area of contamination in groundwater, soil or the air downstream from the source.

pH: A measure of the acidity or basicity of an aqueous solution. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline.

Pesticides: Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest, or intended for use as a plant regulator, defoliant, or desiccant.

Personal Protective Equipment (PPE): Equipment worn to minimize exposure to serious workplace injuries and illnesses. These injuries and illnesses may result from contact with chemical, radiological, physical, electrical, mechanical, or other workplace hazards.

Permit: An authorization, license, or equivalent control document issued by ADEQ to implement the requirements of an environmental regulation, usually to limit the amount of pollutants discharged into the environment. For example, a permit to operate a wastewater treatment plant.

ermeability: The degree to which groundwater can move freely through the rocks and soil of an aquifer, indicative of the degree to which pores and fractures in rocks are actually interconnected. A typical measure of permeability is the number of gallons of water that can move through a cross section of one square foot.

Perennial Water:A surface water that flows continuously throughout the year.

Percolation: The movement under the force of gravity of water downward and radially through subsurface soil layers to the water table. In septic tank installations, a percolation test is used to determine the size of trench needed for adequate disposal of wastewater.

Perchloroethene (also known as tetrachloroethylene) (PCE): Also called tetrachloroethene, PCE, or perc. It is a manufactured chemical widely used for dry cleaning and metal degreasing.

Perchlorate: A manufactured salt that is found in rocket fuels, explosives, flares, fireworks, some bleach products, and some herbicides. Perchlorate can impair thyroid function.

Perched Aquifer: A relatively small, localized aquifer that lies above the regional aquifer and is underlain by a confining layer. Perched aquifers may be formed when the groundwater table drops and water is trapped above a confining layer. They are usually discontinuous and are not usually sources for drinking water.

Pathway: The means for a contaminant to enter the body or plant life. Examples are ingestion (eating or drinking), inhalation (breathing), or transdermal (absorption through the skin). If no pathway exists, then exposure to a contaminant is not possible.

Pathogens: Microorganisms like bacteria, viruses, or parasites that can cause disease in humans, animals and plants.

Parts Per Billion (ppb)/Parts Per MillionMillion (ppm): Units commonly used to express contamination ratios, as in establishing the maximum permissible amount of a contaminant in water, land, or air.

Particulate Matter-2.5 (PM_2.5): Particulate matter measuring 2.5 microns or less. A major pollutant source, it is generated by smoke from wildfires, prescribed burns and fireplace activity.

Particulate Matter-10 (PM₁₀): Dust, particulate matter measuring 10 microns or less. A dust particle of 10 microns is one-seventh the width of a human hair.

Particulate Matter (Inhalable): Any finely divided airborne solid or liquid material with a diameter smaller than 10 micrometers while it is in the air.

Particulate matter: Any finely divided airborne solid or liquid material with a diameter smaller than 100 micrometers while it is in the air. Examples of particulate matter include dust, smoke, soot, pollen and soil particles.

Partial-Body Contact: The recreational use of a surface water that may cause the human body to come into direct contact with the water, but normally not to the point of complete submergence (for example, wading or boating). The use is such that ingestion of the water is not likely and sensitive body organs, such as the eyes, ears, or nose, will not normally be exposed to direct contact with the water.

Ozone Layer: The thin protective layer of gas 10 kilometers to 50 kilometers above the earth that acts as a filter for ultraviolet (UV) radiation from the sun. High UV levels can lead to skin cancer and cataracts and affect the growth of plants.

Ozone: a nearly colorless gas, that appears blue at high concentrations. It is formed in the reaction between atomic oxygen and molecular oxygen. Ozone, produced by photochemical reactions (i.e., sunlight), is found at all altitudes in the atmosphere. Ozone is a strong disinfectant that is sometimes used in drinking water and sewage treatment.

Oxidation: The chemical addition of oxygen to break down pollutants or organic waste; e.g., destruction of chemicals such as cyanides, phenols, and organic sulfur compounds in sewage by bacterial and chemical means.

Overdraft: A condition that occurs in a groundwater basin when pumping exceeds recharge over an extended period of time.

Outstanding Arizona Water: A designated section of surface water by the ADEQ director that affords it the highest protection under the U.S. Clean Water Act.

Outflow: The outward flow of air from a thunderstorm associated with gusty and erratic winds that can result in blowing dust. An outflow is most common during the North American Monsoon season.

Outfall: The place where effluent is discharged into receiving waters.

Osmosis: The passage of a liquid from a weak solution to a more concentrated solution across a semipermeable membrane that allows passage of the solvent (water) but not the dissolved solids.

Organismo Operador de Agua Potable, Alcantarillado y Saneamiento (OOMAPAS): The authority for drinking water, sewerage and sanitation operations in Mexico. Entity responsible for operational aspects of drinking water and wastewater functions in Mexican municipal governments.

Organic Compounds: Carbon-based compounds (also containing oxygen, hydrogen, or nitrogen) most commonly associated with living organisms  like proteins, sugars and cellulose.

Operator Certificate: Certification of operators of community and nontransient noncommunity water systems, asbestos specialists, pesticide applicators, hazardous waste transporters, and other such specialists as required by the EPA or ADEQ implementing an EPA-approved program.

Operation and Maintenance (O&M): 1. Activities conducted after a Superfund site action is completed to ensure that the action is effective;  2. Actions taken after construction to ensure that facilities constructed to treat wastewater will be properly operated and maintained to achieve normative efficiency levels and prescribed effluent limitations in an optimum manner; 3. On-going asbestos management plan in a school or other public building, including regular inspections, various methods of maintaining asbestos in place, and removal when necessary.

Operable Unit: Term for each of a number of separate activities undertaken as part of a Superfund site cleanup.

Opacity: The amount of light obscured by particulate pollution in the air; clear window glass has zero opacity, a brick wall is 100 percent opaque. Opacity is an indicator of changes in performance of particulate control systems.

On-Screen Coordinator: The predesignated EPA, Coast Guard, or Department of Defense official who coordinates and directs Superfund removal actions or Clean Water Act oil- or hazardous-spill response actions.

Occupational Safety and Health Administration (OSHA): Created by Congress to assure safe and healthful working conditions for workers by setting and enforcing standards and by providing training, outreach, education and assistance.

Nutrient: Any substance assimilated by living things that promotes growth. The term is often applied to nitrogen and phosphorus in wastewater, where excessive amounts create algae growth and other problems, but is also applied to other essential and trace elements.

Nuclear Regulatory Commission (NRC): The NRC was created as an independent agency by Congress in 1974 to ensure the safe use of radioactive materials for beneficial civilian purposes while protecting people and the environment. The NRC regulates commercial nuclear power plants like Palo Verde Nuclear Generating Station west of Phoenix.

Noxious Gases: Poisonous gases that can harm people and the environment. Some gases have a strong smell, for example sulfur dioxide and methane, while others, such as carbon monoxide, do not have any smell at all.

Notice of Violation (NOV): An informal enforcement action taken by ADEQ which documents the factual nature of an environmental violation, the legal authority regarding compliance, a description of what constitutes compliance and how it is to be documented and a time frame in which ADEQ expects compliance to be achieved. NOVs are issued for violations considered to pose higher environmental risk than NOC violations

Notice of Opportunity to Correct (NOC): An informal enforcement action taken by ADEQ which documents the factual nature of an environmental violation, the legal authority regarding compliance, a description of what constitutes compliance and how it is to be documented and a time frame in which ADEQ expects compliance to be achieved. NOCs are issued for violations considered to pose less environmental risk than NOV violations.

North American Development Bank (NADB): Created with the Border Environment Cooperation Commission (BECC) as an interdependent institution, NADB concentrates on project financing and oversight for project implementation to preserve and enhance environmental conditions for people living along the U.S.-Mexico border.

Non-Point Sources: Diffuse pollution sources (i.e. without a single point of origin or not introduced into a receiving stream from a specific outlet). The pollutants are generally carried off the land by storm water. Common non-point sources are agriculture, forestry, urban, mining, construction, dams, channels, land disposal, saltwater intrusion, and city streets.

Non-Attainment Area: Area that does not meet one or more of the National Ambient Air Quality Standards for the criteria pollutants designated in the Clean Air Act.

No Burn Day: Admonition to not burn wood issued by Maricopa County Air Quality Department when forecasted soot, dust or ozone conditions have led to issuance of a high pollution advisory or health watch by ADEQ.

Nitrogen oxides:Any inorganic compound containing both nitrogen and oxygen. These compounds act as precursors to other pollutants such as nitrate and ozone.

Nitrate: A compound containing nitrogen and oxygen that exists in the atmosphere or as a dissolved gas in water and has harmful effects on humans and animals. Nitrates in water can cause severe illness in infants and domestic animals. A plant nutrient and inorganic fertilizer, nitrate is found in septic systems, animal feed lots, agricultural fertilizers, manure, industrial waste waters, and sanitary landfills.

New Source Review: A Clean Air Act requirement that state implementation plans must include a permit review that applies to the construction and operation of new and modified stationary sources in nonattainment areas to ensure attainment of national ambient air quality standards.

New Source Performance Standards: Uniform national EPA air emission and water effluent standards which limit the amount of pollution allowed from new sources or from modified existing sources.

Navigable Waters: Traditionally, waters sufficiently deep and wide for navigation by all, or specified vessels. Such waters in the United States come under federal jurisdiction and are protected by certain provisions of the Clean Water Act.

National Response Team: Representatives of 13 federal agencies that, as a team, coordinate federal responses to nationally significant incidents of pollution — an oil spill, a major chemical release, or a superfund response action — and provide advice and technical assistance to the responding agency(ies) before and during a response action.

National Response Center (NRC): The federal government’s national communications center, which is staffed by U.S. Coast Guard officers and marine science technicians. The NRC is the sole federal point of contact for reporting all hazardous substances releases and oil spills.

National Priorities List (NPL): EPA’s list of the most serious hazardous waste sites identified for possible long-term remedial response under the federal superfund (CERCLA).

National Pollution Discharge Elimination System (NPDES): Provision of the Clean Water Act which prohibits discharge of pollutants into waters of the United States unless a special permit is issued by EPA, a state, or, where delegated, a tribal government on an Indian reservation.

National Institute for Occupational Safety and Health (NIOSH): The federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the Centers for Disease Control and Prevention.

National Environmental Policy Act of 1969: An act that established a U.S. national policy promoting the enhancement of the environment. NEPA’s most significant accomplishment was setting up procedural requirements for all federal government agencies to prepare environmental assessments and environmental impact statements.

National Emissions Standards for Hazardous Air Pollutants (NESHAP): Emissions standards set by EPA for an air pollutant not covered by NAAQS that may cause an increase in fatalities or in serious, irreversible, or incapacitating illness. Primary standards are designed to protect human health, secondary standards to protect public welfare like building facades, visibility, crops, and domestic animals.

National Ambient Air Quality Standards (NAAQS): Federal standards for the minimum ambient air quality needed to protect public health and welfare.

Multiple Use: Use of land for more than one purpose like grazing of livestock, watershed and wildlife protection, recreation, and timber production. Also applies to use of bodies of water for recreational purposes, fishing, and water supply.

Monsoon (North American): A seasonal change in prevailing winds accompanied by corresponding increase in precipitation. It describes the seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea. Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry phase. It is formally defined as occurring from June 15 to September 30.

Monitoring Wells: Wells installed for the purpose of collecting samples such as groundwater and soil gas. Analytical results from samples are used to characterize the extent of contamination, the direction of groundwater flow, and the types and quantities of contaminants present in the groundwater.

Monitoring Assistance Program (MAP): ADEQ program designed to lessen the monitoring and financial burdens on small public water systems in Arizona to ensure that all water served meets state and federal safe drinking water standards.

Monitored Natural Attenuation (MNA): Describes a range of physical and biological processes which, unaided by human intervention, reduce the concentration, toxicity, or mobility of chemical or radioactive contaminants. These processes take place whether or not other active cleanup measures are in place.

Mixing Zone: an area or volume of a surface water that is contiguous to a point source discharge where dilution of the discharge takes place.

Mixing Height: The height to which the lower atmosphere will undergo mechanical or turbulent mixing, producing a nearly uniform air mass.

Million Gallons per Day (MGD): A measure of water flow often used for indicating the treatment capacity of sewage treatment plants or production capacity of drinking water treatment plants. One MGD is equivalent to about 700 gallons per minute or 1.5 cubic feet per second.

Milligrams per Liter (mg/L): A unit of measurement that expresses a concentration that is the mass (weight) of one material dissolved into a volume of another material. A milligram is a metric unit of mass equal to 0.0000022 pounds or 1000 micrograms. A liter is a metric unit of volume approximately equivalent to 1 quart. Also, 1 mg/L is equivalent to 1 part per million (ppm).

Migration: The movement of a contaminant in the environment through soil, groundwater, surface water, air, etc.

Micrograms per Liter (μg/L) : A unit of measurement that expresses a concentration that is the mass (weight) of one material dissolved into a volume of another material. A microgram (μg) is a metric unit of mass which is equivalent to 0.0000000022 pounds. A liter is a metric unit of volume which is approximately equivalent to a quart. Also, 1 μg/L is equivalent to 1 part per billion (ppb).

Methane: A colorless, non-poisonous, flammable gas created by microorganisms as they digest (anaerobic decomposition) organic compounds found in landfill wastes. Methane is found in nature as a gas and is the major component of the gas that provides energy for our homes.

Medical Waste Incinerator (MWI): Incineration equipment that burns wastes produced by hospitals, veterinary facilities, and medical research facilities. These wastes include both infectious medical wastes as well as non-infectious, general housekeeping wastes.

Maximum Contaminant Level (MCL): A federally designated, enforceable drinking water standard set to ensure that water is safe for drinking and other uses. The MCL varies for each contaminant being analyzed.

Maricopa Association of Governments (MAG): Regional air quality planning agency and metropolitan planning organization for transportation for all jurisdictions in Maricopa County, including the Phoenix urbanized area and the contiguous urbanized area in Pinal County, including the Town of Florence and City of Maricopa.

Manifest (Hazardous Waste): The shipping document, originated and signed by a waste generator or his or her representative, that is required by state or federal environmental regulators.

Leaking Underground Storage Tank (LUST): Petroleum releases from regulated underground storage tanks.

Lead: A heavy metal that is hazardous to health if breathed or swallowed. Its use in gasoline, paints and plumbing compounds has been sharply restricted or eliminated by federal laws and regulations.

Leachate: Liquid that forms when water passes down through solid waste, carrying suspended particles and chemicals it picks up and dissolves along the way into the ground and groundwater below. For example, rain falling on a landfill and passing through the waste would appear as leachate below the waste.