RCRA Glossary of Terms
Administrative Order On Consent: A legal agreement signed by EPA and an individual, business, or other entity through which the violator agrees to pay for correction of violations, take the required corrective or cleanup actions, or refrain from an activity. It describes the actions to be taken, may be subject to a comment period, applies to civil actions, and can be enforced in court.
Aeration: A process which promotes biological degradation of organic matter in water. The process may be passive (as when waste is exposed to air), or active (as when a mixing or bubbling device introduces the air).
Aerobic Treatment: Process by which microbes decompose complex organic compounds in the presence of oxygen and use the liberated energy for reproduction and growth. (Such processes include extended aeration, trickling filtration, and rotating biological contactors.)
Affected Public: 1.The people who live and/or work near a hazardous waste site. 2. The human population adversely impacted following exposure to a toxic pollutant in food, water, air, or soil.
Air Stripping: A treatment system that removes volatile organic compounds (VOCs) from contaminated ground water or surface water by forcing an airstream through the water and causing the compounds to evaporate.
Alluvial: Relating to and/or sand deposited by flowing water.
Aqueous: Something made up of water.
Aquifer: An underground geological formation, or group of formations, containing water. Are sources of groundwater for wells and springs.
Arsenic: Please see the ATSDR fact sheet for arsenic.
Attenuation: The process by which a compound is reduced in concentration over time, through absorption, adsorption, degradation, dilution, and/or transformation. an also be the decrease with distance of sight caused by attenuation of light by particulate pollution.
ATSDR: Agency for Toxic Substances and Disease Registry (ATSDR) is charged under the Superfund Act to assess the presence and nature of health hazards at specific Superfund sites, to help prevent or reduce further exposure and the illnesses that result from such exposures, and to expand the knowledge base about health effects from exposure to hazardous substances
Background Level: 1. The concentration of a substance in an environmental media (air, water, or soil) that occurs naturally or is not the result of human activities. 2. In exposure assessment the concentration of a substance in a defined control area, during a fixed period of time before, during, or after a data-gathering operation.
Benzene: Please see the ATSDR fact sheet for benzene.
Bioremediation: Use of living organisms to clean up oil spills or remove other pollutants from soil, water, or wastewater; use of organisms such as non-harmful insects to remove agricultural pests or counteract diseases of trees, plants, and garden soil.
Brownfields: Abandoned, idled, or under used industrial and commercial facilities/sites where expansion or redevelopment is complicated by real or perceived environmental contamination. They can be in urban, suburban, or rural areas. EPA's Brownfields initiative helps communities mitigate potential health risks and restore the economic viability of such areas or properties.
Cap: A layer of clay, or other impermeable material installed over the top of a closed landfill to prevent entry of rainwater and minimize leachate.
Carcinogen: Any substance that can cause or aggravate cancer.
Chlorinated Solvent: An organic solvent containing chlorine atoms(e.g., methylene chloride and 1,1,1-trichloromethane). Uses of chlorinated solvents are include aerosol spray containers, in highway paint, and dry cleaning fluids.
Chromated Copper Arsenate:A water-borne preservative containing active ingredients that are inorganic metal oxides, or less frequently salts, and are commonly used to treat dimentional lumber and telephone poles.
Chromium: Please see the ATSDR fact sheet for chromium.
Cleanup: Actions taken to deal with a release or threat of release of a hazardous substance that could affect humans and/or the environment. The term "cleanup" is sometimes used interchangeably with the terms remedial action, removal action, response action, or corrective action.
Combustion: 1. Burning, or rapid oxidation, accompanied by release of energy in the form of heat and light. 2. Refers to controlled burning of waste, in which heat chemically alters organic compounds, converting into stable inorganics such as carbon dioxide and water.
Comment Period: Time provided for the public to review and comment on a proposed EPA action or rulemaking after publication in the Federal Register.
Composting: The controlled biological decomposition of organic material in the presence of air to form a humus-like material. Controlled methods of composting include mechanical mixing and aerating, ventilating the materials by dropping them through a vertical series of aerated chambers, or placing the compost in piles out in the open air and mixing it or turning it periodically.
Consent Decree (Order): A legal document, approved by a judge, that formalizes an agreement reached between EPA and potentially responsible parties (PRPs) through which PRPs will conduct all or part of a cleanup action at a Superfund site; cease or correct actions or processes that are polluting the environment; or otherwise comply with EPA initiated regulatory enforcement actions to resolve the contamination at the Superfund site involved. The consent decree describes the actions PRPs will take and may be subject to a public comment period.
Constituent(s) of Concern: Specific chemicals that are identified for evaluation in the site assessment process.
Contaminant: Any physical, chemical, biological, or radiological substance or matter that has an adverse effect on air, water, or soil.
Corrective Action: EPA can require treatment, storage and disposal (TSDF) facilities handling hazardous waste to undertake corrective actions to clean up spills resulting from failure to follow hazardous waste management procedures or other mistakes. The process includes cleanup procedures designed to guide TSDFs toward in spills.
Creosote: Please see the ATSDR fact sheet for creosote.
Dense Non-Aqueous Phase Liquid (DNAPL): Non-aqueous phase liquids such as chlorinated hydrocarbon solvents or petroleum fractions with a specific gravity greater than 1.0 that sink through the water column until they reach a confining layer. Because they are at the bottom of aquifers instead of floating on the water table, typical monitoring wells do not indicate their presence.
Designer Bugs: Popular term for microbes developed through biotechnology that can degrade specific toxic chemicals at their source in toxic waste dumps or in ground water.
1,1-DCA (dichloroethane): Please see the ATSDR fact sheet for 1,1-DCA.
1,1 Dichloroethylene or 1,1 Dichloroethene: Please see the ATSDR fact sheet for 1,1 Dichloroethylene or 1,1 Dichloroethene.
Dioxin: Any of a family of compounds known chemically as dibenzo-p-dioxins. Concern about them arises from their potential toxicity as contaminants in commercial products. Tests on laboratory animals indicate that it is one of the more toxic anthropogenic (man-made) compounds.
Dioxins/Furans: Please see the ATSDR fact sheet for dioxins/furans.
Disposal: Final placement or destruction of toxic, radioactive, or other wastes; surplus or banned pesticides or other chemicals; polluted soils; and drums containing hazardous materials from removal actions or accidental releases. Disposal may be accomplished through use of approved secure landfills, surface impoundments, land farming, deep-well injection, ocean dumping, or incineration.
Downgradienat: The direction that groundwater flows; similar to "downstream" for surface water.
Ecological Risk Assessment: The application of a formal framework, analytical process, or model to estimate the effects of human actions(s) on a natural resource and to interpret the significance of those effects in light of the uncertainties identified in each component of the assessment process. Such analysis includes initial hazard identification, exposure and dose-response assessments, and risk characterization.
Engineered Controls: Method of managing environmental and health risks by placing a barrier between the contamination and the rest of the site, thus limiting exposure pathways.
Environmental Indicator: A measurement, statistic or value that provides a proximate gauge or evidence of the effects of environmental management programs or of the state or condition of the environment.
Environmental Justice (EJ): The fair treatment and meaningful involvement of all people--regardless of race, color, national origin, or income--in the development, implementation, and enforcement of environmental laws, regulations, and policies.
Environmental Site Assessment: The process of determining whether contamination is present on a parcel of real property.
Exposure Pathway: The path from sources of pollutants via, soil, water, or food to man and other species or settings.
Flocculation: Process by which clumps of solids in water or sewage aggregate through biological or chemical action so they can be separated from water or sewage.
Flue Gas: The air coming out of a chimney after combustion in the burner it is venting. It can include nitrogen oxides, carbon oxides, water vapor, sulfur oxides, particles and many chemical pollutants.
Fly Ash: Non-combustible residual particles expelled by flue gas.
Generator: 1. A facility or mobile source that emits pollutants into the air or releases hazardous waste into water or soil.
Ground Water: The supply of fresh water found beneath the Earth's surface, usually in aquifers, which supply wells and springs. Because ground water is a major source of drinking water, there is growing concern over contamination from leaching agricultural or industrial pollutants or leaking underground storage tanks.
Hazardous Waste: By-products of society that can pose a substantial or potential hazard to human health or the environment when improperly managed. Possesses at least one of four characteristics (ignitability, corrosivity, reactivity, or toxicity), or appears on special EPA lists.
Hazardous Waste Management Unit (HWMU):
Heavy Metals: Metallic elements with high atomic weights; (e.g., mercury, chromium, cadmium, arsenic, and lead); can damage living things at low concentrations and tend to accumulate in the food chain.
Human Health Risk: The likelihood that a given exposure or series of exposures may have damaged or will damage the health of individuals.
Imminent Hazard: One that would likely result in unreasonable adverse effects on humans or the environment or risk unreasonable hazard to an endangered species during the time required for a pesticide registration cancellation proceeding.
Impermeable: Not easily penetrated. The property of a material or soil that does not allow, or allows only with great difficulty, the movement or passage of water.
Impoundment: A body of water or sludge confined by a dam, dike, floodgate, or other barrier.
Incineration: A treatment technology involving destruction of waste by controlled burning at high temperatures; e.g., burning sludge to remove the water and reduce the remaining residues to a safe, non-burnable ash that can be disposed of safely on land, in some waters, or in underground locations.
Industrial Process Waste: Residues produced during manufacturing operations.
Industrial Sludge: Semi-liquid residue or slurry remaining from treatment of industrial water and wastewater.
Interim (Permit) Status: Period during which treatment, storage and disposal facilities coming under RCRA in 1980 are temporarily permitted to operate while awaiting a permanent permit. Permits issued under these circumstances are usually called "Part A" or "Part B" permits.
Lagoon: 1. A shallow pond where sunlight, bacterial action, and oxygen work to purify wastewater; also used for storage of wastewater or spent nuclear fuel rods.
Land Disposal Restrictions: Rules that require hazardous wastes to be treated before disposal on land to destroy or immobilize hazardous constituents that might migrate into soil and ground water.
Land Farming (of Waste): A disposal process in which hazardous waste deposited on or in the soil is degraded naturally by microbes.
Large Quantity Generator: Person or facility generating more than 2200 pounds of hazardous waste per month. Such generators produce about 90 percent of the nation's hazardous waste, and are subject to all RCRA requirements.
Leachate: Water that collects contaminants as it trickles through wastes, pesticides or fertilizers. Leaching may occur in farming areas, feedlots, and landfills, and may result in hazardous substances entering surface water, ground water, or soil.
Lift: In a sanitary landfill, a compacted layer of solid waste and the top layer of cover material.
Light Non-Aqueous Phase Liquid (LNAPL): A non-aqueous phase liquid with a specific gravity less than 1.0. Because the specific gravity of water is 1.0, most LNAPLs float on top of the water table. Most common petroleum hydrocarbon fuels and lubricating oils are LNAPLs.
Liner: A relatively impermeable barrier designed to keep leachate inside a landfill. Liner materials include plastic and dense clay.
Mechanical Aeration: Use of mechanical energy to inject air into water to cause a waste stream to absorb oxygen.
Media: Specific environments--air, water, soil--which are the subject of regulatory concern and activities.
Mercury (Hg): Heavy metal that can accumulate in the environment and is highly toxic if breathed or swallowed.
Mining Waste: Residues resulting from the extraction of raw materials from the earth.
Monitoring: Periodic or continuous surveillance or testing to determine the level of compliance with statutory requirements and/or pollutant levels in various media or in humans, plants, and animals.
Monitoring Well: 1. A well used to obtain water quality samples or measure groundwater levels. 2. A well drilled at a hazardous waste management facility or Superfund site to collect ground-water samples for the purpose of physical, chemical, or biological analysis to determine the amounts, types, and distribution of contaminants in the groundwater beneath the site.
Mulch: A layer of material (wood chips, straw, leaves, etc.) placed around plants to hold moisture, prevent weed growth, and enrich or sterilize the soil.
Multi-Media Approach: Joint approach to several environmental media, such as air, water, and land.
Necrosis: Death of plant or animal cells or tissues. In plants, necrosis can discolor stems or leaves or kill a plant entirely.
Neutralization: Decreasing the acidity or alkalinity of a substance by adding alkaline or acidic materials, respectively.
Nitrate: A compound containing nitrogen that can exist in the atmosphere or as a dissolved gas in water and which can have 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, sanitary landfills, and garbage dumps.
Non-Aqueous Phase Liquid (NAPL): Contaminants that remain undiluted as the original bulk liquid in the subsurface, e.g., spilled oil.
Off-Site Facility: A hazardous waste treatment, storage or disposal area that is located away from the generating site.
On-Site Facility: A hazardous waste treatment, storage or disposal area that is located on the generating site.
Organic: 1. Referring to or derived from living organisms. 2. In chemistry, any compound containing carbon.
Organic Matter: Carbonaceous waste contained in plant or animal matter and originating from domestic or industrial sources.
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.
Outfall: The place where effluent is discharged into receiving waters.
Oxidation Pond: A man-made (anthropogenic) body of water in which waste is consumed by bacteria, used most frequently with other waste-treatment processes; a sewage lagoon.
Particulates: 1. Fine liquid or solid particles such as dust, smoke, mist, fumes, or smog, found in air or emissions. 2. Very small solids suspended in water; they can vary in size, shape, density and electrical charge and can be gathered together by coagulation and flocculation.
Passive Treatment Walls: Technology in which a chemical reaction takes place when contaminated ground water comes in contact with a barrier such as limestone or a wall containing iron filings.
Pentachlorophenol: Please see the ATSDR fact sheet for Pentachlorophenol.
PCE or PERC (tetrachloroethylene): Please see the ATSDR fact sheet for PERC.
Perched Water: A zone of unpressurized water held above the water table by impermeable rock or sediment.
Percolation: 1. The movement of water downward and radially through subsurface soil layers, usually continuing downward to ground water. Can also involve upward movement of water. 2. Slow seepage of water through a filter.
Permeability: The rate at which liquids pass through soil or other materials in a specified direction.
Permit: An authorization, license, or equivalent control document issued by EPA or an approved state agency to implement the requirements of an environmental regulation; e.g., a permit to operate a wastewater treatment plant or to operate a facility that may generate harmful emissions.
Pesticide: Substances or mixture there of intended for preventing, destroying, repelling, or mitigating any pest. Also, any substance or mixture intended for use as a plant regulator, defoliant, or desiccant.
pH: An expression of the intensity of the basic or acid condition of a liquid; may range from 0 to 14, where 0 is the most acid and 7 is neutral. Natural waters usually have a pH between 6.5 and 8.5.
Phytotreatment: The cultivation of specialized plants that absorb specific contaminants from the soil through their roots or foliage. This reduces the concentration of contaminants in the soil, but incorporates them into biomasses that may be released back into the environment when the plant dies or is harvested.
Pilot Tests: Testing a cleanup technology under actual site conditions to identify potential problems prior to full-scale implementation.
Plugging: Act or process of stopping the flow of water, oil, or gas into or out of a formation through a borehole or well penetrating that formation.
Plume: 1. A visible or measurable discharge of a contaminant from a given point of origin. Can be visible or thermal in water, or visible in the air as, for example, a plume of smoke.
Point Source: A stationary location or fixed facility from which pollutants are discharged; any single identifiable source of pollution; e.g., a pipe, ditch, ship, ore pit, factory smokestack
Pollutant: Generally, any substance introduced into the environment that adversely affects the usefulness of a resource or the health of humans, animals, or ecosystems.
Polychlorinated Biphenyls (PCBs): Please see the ATSDR fact sheet for PCBs.
Polycyclic Aromatic Hydrocarbons (PAHs): Please see the ATSDR fact sheet for polycyclic aromatic hydrocarbons.
Post-Closure: The time period following the shutdown of a waste management or manufacturing facility; for monitoring purposes, often considered to be 30 years.
Preliminary Assessment: The process of collecting and reviewing available information about a known or suspected waste site or release.
Proposed Plan: A plan for a site cleanup that is available to the public for comment.
PRP: Potentially Responsible Parties (PRPs) are individuals, companies, or any other party that are potentially liable for payment of Superfund cleanup costs.
Public Comment Period: The time allowed for the public to express its views and concerns regarding an action by EPA (e.g., a Federal Register Notice of proposed rule-making, a public notice of a draft permit, or a Notice of Intent to Deny).
Public Notice: 1. Notification by EPA informing the public of Agency actions such as the issuance of a draft permit or scheduling of a hearing. EPA is required to ensure proper public notice, including publication in newspapers and broadcast over radio and television stations.
RCRA: The Resource Conservation and Recovery Act (RCRA) protects human health and the environment from the potential hazards of waste disposal, conserves energy and natural resources, reduces the amount of waste generated, and ensures that wastes are managed in an environmentally sound manner.
RCRA Facility Assessment. A step in the RCRA Subtitle C corrective action process where owners and operators compile existing information on environmental conditions at a given facility, including information on actual and potential releases.
RCRA Facility Investigation (RFI). Site characterization used to ascertain the nature and extent of contamination of releases identified during a Subtitle C RCRA facility assessment or the Phase 1 RCRA facility investigation.
RCRA 3008 Order: Order 3008(h) authorizes EPA to issue administrative (i.e., enforcement) orders or bring court action to require corrective action or other measures when there is or has been a release of hazardous waste or hazardous constituents from a RCRA facility operating under interim status.
Release: Any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment of a hazardous or toxic chemical or extremely hazardous substance.
Remedial Response: Long-term action that stops or substantially reduces a release or threat of a release of hazardous substances that is serious but not an immediate threat to public health.
Remediation: Cleanup or other methods used to remove or contain a toxic spill or hazardous materials from a hazardous waste site.
Removal Action: Short-term immediate actions taken to address releases of hazardous substances that require expedited response. (See: cleanup.)
Responsiveness Summary: A summary of oral and/or written public comments received by EPA during a comment period on key EPA documents, and EPA's response to those comments.
Retrofit: Addition of a pollution control device on an existing facility without making major changes to the generating plant. Also called backfit.
Rotary Kiln Incinerator: An incinerator with a rotating combustion chamber that keeps waste moving, thereby allowing it to vaporize for easier burning.
Seepage: Percolation of water through the soil from unlined canals, ditches, laterals, watercourses, or water storage facilities.
Sink: Place in the environment where a compound or material collects.
Sludge: A semi-solid residue from any of a number of air or water treatment processes; can be a hazardous waste.
Small Quantity Generator (SQG-sometimes referred to as "Squeegee"): Persons or enterprises that produce 220-2200 pounds per month of hazardous waste. The largest category of hazardous waste generators, SQGs, include automotive shops, dry cleaners, photographic developers, and many other small businesses. (See: conditionally exempt generators.)
Solid Waste Management Unit: A discernible unit where solid or hazardous wastes have been placed at any time, or any area where solid wastes have been routinely and systematically released.
Sparge or Sparging: Injection of air below the water table to strip dissolved volatile organic compounds and/or oxygenate ground water to facilitate aerobic biodegradation of organic compounds.
Spoil: Dirt or rock removed from its original location--destroying the composition of the soil in the process--as in strip-mining, dredging, or construction.
Stakeholder: Any organization, governmental entity, or individual that has a stake in or may be impacted by a given approach to environmental regulation, pollution prevention, energy conservation, etc.
Storage: Temporary holding of waste pending treatment or disposal, as in containers, tanks, waste piles, and surface impoundments.
Sump: A pit or tank that catches liquid runoff for drainage or disposal.
Surface Impoundment: Treatment, storage, or disposal of liquid hazardous wastes in ponds.
Surface Water: All water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries, etc.)
Tailings: Residue of raw material or waste separated out during the processing of crops or mineral ores.
Tetrachloroethylene (PCE or PERC): Please see the ATSDR fact sheet for PERC.
Thermal Treatment: Use of elevated temperatures to treat hazardous wastes.(See: incineration; pyrolysis.)
Toluene: Please see the ATSDR fact sheet for toluene.
Topography: The physical features of a surface area including relative elevations and the position of natural and man-made (anthropogenic) features.
The Toxic Substances Control Act (TSCA): Enables EPA to track the 75,000 industrial chemicals currently produced or imported into the U.S. EPA repeatedly screens these chemicals and can require reporting or testing of those that may pose an environmental or human-health hazard. EPA can ban the manufacture and import of those chemicals that pose an unreasonable risk.
Toxics Release Inventory (TRI): A database that contains information concerning waste management activities andthe release of toxic chemicals by facilities that manufacture, process, or otherwise use such materials. Citizens, businesses, and governments can then use this information to work together to protect the quality of their land, air, and water.
Toxic Substance: A chemical or mixture that may present an unreasonable risk of injury to health or the environment.
Toxicity: The degree to which a substance or mixture of substances can harm humans or animals. Acute toxicity involves harmful effects in an organism through a single or short-term exposure.
1,1,1-TCA (trichloroethane): Please see the ATSDR fact sheet for 1,1,1-TCA.
TCE (trichloroethene): Please see the ATSDR fact sheet for TCE.
Unconfined Aquifer: An aquifer containing water that is not under pressure; the water level in a well is the same as the water table outside the well.
Underground storage tank system (UST): A tank and any underground piping connected to the tank that has at least 10 percent of its combined volume underground. Under the Resource Conservation and Recovery Act (RCRA), EPA has established regulatory programs to prevent, detect, and clean up releases from USTs containing petroleum or hazardous substances.
Volatile Liquids: Liquids which easily vaporize or evaporate at room temperature.
Volatile Solids: Those solids in water or other liquids that are lost on ignition of the dry solids at 550° centigrade.
Water Quality Criteria: Levels of water quality expected to render a body of water suitable for its designated use. Criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.
Watershed: The land area that drains into a stream; the watershed for a major river may encompass a number of smaller watersheds that ultimately combine at a common point.
Wood Treatment Facility: An industrial facility that treats lumber and other wood products for outdoor use. The process employs chromated copper arsenate, which is regulated as a hazardous material.
Xylene: Please see the ATSDR fact sheet for xylene.