Glossary - Ashland

Adsorption- adhesion of contaminants to liquids or solids

Aerobic- living or active in the presence of oxygen

Anaerobic-living or active in the absence of oxygen

Applicable or Relevant and Appropriate Requirement (ARAR) – ARARs are cleanup standards, standards of control, and other substantive environmental protection requirements, criteria, or limits originating from Federal or state law that specifically address problems or situations present at a CERCLA site. ARAR’s are major considerations in setting cleanup goals, selecting a remedy, and determining how to implement that remedy at a CERCLA site. ARARs must be attained at all CERCLA sites unless a waiver is granted.

Aquifer - an aquifer is an underground rock formation composed of materials such as sand, soil, and gravel that can store underground water and supply it to wells and springs.

Aromatics- organic compounds that contain 6 carbon ring structures, such as creosote, toluene and phenol.

Bedrock- rock that underlies the soil; may be permeable or non-permeable.

Bioremediation- treatment processes that use microorganisms (bacteria, yeast, fungi) to break down hazardous substances. The organisms may consume the contaminant as food producing CO2, water and cells or may break down the contaminant to an intermediate compound. The intermediate compound in some cases may be more toxic or mobile than the original compound.

Borehole- a hole cut in the ground by a drilling rig.

BTEX- volatile organic compounds commonly found in fuels. Typical sites containing BTEX include former gas stations, refineries, and military installations.

BTEX= Benzene, Toluene, Ethyl Benzene, Xylene

Carcinogen- cancer causing agent.

Chlorinated- compound containing chlorine.

Chronic Toxicity- the effect of low-level, long-term exposure

Cleanup- actions taken to deal with a release or threat of release of a hazardous substance that could affect humans or the environment. Sometimes used interchangeably with the terms remedial action, removal action, response action, or corrective action.

Clean Water Act (CWA)- CWA is a 1977 amendment to the Federal Water Pollution Control Act of 1972, which sets the basic structure for regulating discharges of pollutants to U.S. waters. This law gave EPA the authority to set discharge standards on an industry-by-industry basis and to set water quality standards for all contaminants in surface waters.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)- CERCLA is a Federal law passed in 1980 that created a special tax that funds a trust fund, commonly called Superfund, to be used to investigate and clean up abandoned or uncontrolled hazardous waste sites. The EPA can pay for cleanup when parties responsible for the contamination cannot be located or are unwilling or unable to perform the work, or take legal action to force parties responsible for contamination to clean up the sites or reimburse the government for the cost of the cleanup.

Comprehensive Environmental Response, Compensation and Liability Information System (CERCLIS)- CERCLIS is a database that serves as the official inventory of Superfund hazardous waste sites. The database maintains information about planned and actual site activities and financial information entered by EPA regional offices.

Concentration- the relative amount of a substance mixed with another substance. An example is five parts per million of carbon monoxide in air or 1 milligram/liter of iron in water.

Confining Layer- a geological formation characterized by low permeability that inhibits the vertical flow of water.

Contaminants- toxic or hazardous substances in soil, water or air that may increase health risks, depending on likelihood of exposure and toxicity. Cadmium, dioxin, TCE, benzene, and carbon tetrachloride are examples of contaminants.

Corrosivity- a measure of a substance's ability to corrode metals such as those found in tanks and 55 gallon drums.

Data Quality Objective (DQO)- a statement used to ensure that data of known and appropriate quality are obtained. The DQO process involves a logical, step-by-step procedure for determining which of the complex issues affecting a site are the most relevant to planning a site investigation before any data are collected.

DNAPL-Dense Non-Aqueous Phase Liquids are liquids that are denser than water and are organics. DNAPL's may be difficult to treat since they tend to accumulate above low permeability layers (or aquitards) in the ground.

Dechlorination- a process used primarily to treat and destroy halogenated aromatic contaminants. Dechlorination is the chemical reaction that removes halogens from the primary structure of the contaminant.

Degradation- reducing the chemical complexity of a compound. Fuels may be degraded by organisms from their original state to CO₂, cell matter and water rendering them harmless.

Disposal- the final placement or destruction of toxic, radioactive or other wastes. Disposal may be accomplished through the use of approved secure landfills, surface impoundments, landfarming, deep well injection, ocean dumping, or incineration.

Electromagnetic Induction- a geophysical technology used to detect and measure buried debris using magnetic fields.

Emergency Removal- an action initiated in response to a release of a hazardous substance that requires onsite activity within hours of a determination that action is appropriate.

Emerging Technology- an innovative technology undergoing bench scale testing.

Enforcement Action- an action undertaken by EPA under its authority granted under various Federal environmental statures such as CERCLA, RCRA, CAA, CWA, TSCA, and others.

Engineered control- a method of managing environmental and health risks. A barrier placed between contamination and the rest of a site is an example of an engineered control.

Exposure pathway- route of contaminants from the source of contamination to potential contact with a "receptor" (any living organism, including humans). For example gasoline leaking from an Underground Storage Tank to surrounding soil is an exposure pathway.

Ex situ- occurring out of the ground. Ex-situ treatment of contaminants involves the removal of the contaminant from the ground prior to treatment.

Exposure- radiation or pollutants that come into contact with the body and present a potential health threat. The most common routes of exposure are through the skin, mouth or by inhalation.

Gas chromatography- an analytical method used to identify VOCs and SVOCs.

Groundwater- water found in the ground that saturates the pores of soil, sand and rock formations. Groundwater pumped from the ground may be used as drinking water.

Halogen- a class of elements containing fluorine, chlorine, bromine, or iodine, and that are commonly found in pairs (e.g., Cl₂)

Hazard ranking system (HRS)- a primary screening tool used by EPA to assess the risks posed to human health or the environment by abandoned or uncontrolled hazardous waste sites. Under the HRS, sites are assigned scores on the basis of the toxicity of hazardous substances that are present and the potential that those substances will spread through the air, surface, water, or groundwater, taking into account such factors as the proximity of the substance to nearby populations.

Hazardous substance- any material that poses a threat to public health or the environment. Typical hazardous wastes are toxic, corrosive, ignitable, explosive, or chemically reactive. Petroleum, crude oil, natural gas, natural gas liquids or synthetic gas usable for fuel are not considered hazardous substances.

Hazardous and Solid Waste Amendments (HSWA)- 1984 amendments to RCRA which required phasing out land disposal of hazardous waste and added minimum technology requirements.

Heavy metal- a group of toxic metals including arsenic, chromium, copper, lead, mercury, silver, and zinc.

Hydrocarbons- an organic compound containing only carbon and hydrogen and often found occurring in petroleum, natural gas and coal.

Hydrogeology- study of groundwater including its origin, occurrence, movement, and quality.

Hydrology- science that deals with the properties, movement, and effects of water found on the earth’s surface, in the soil and rocks beneath the surface, and in the atmosphere.

Ignitability- the tendency to cause fires under certain conditions.

Information repository- a location in a public building that contains information about a Superfund site, including technical reports and reference documents.

In situ- occurring in place. An in-situ treatment process cleans up contaminants where they are found, and excavation or pumping is not required.

Inorganic- a substance which contains ingredients other than only carbon and hydrogen. Metals, rocks, and asbestos are inorganic substances.

Ion- an atom that has lost or gained electron(s). A sodium atom that has given up a single electron is symbolized as Na+ and is a sodium ion with a positive electrical charge.

Institutional controls- a legal or institutional measure that forces a property owner to limit activities at, or access to, a property. They are used to ensure protection of human health and the environment. Fences, signs, zoning and deed restrictions are all examples of institutional controls.

Integrated Risk Information System (IRIS)- an electronic database that contains EPA’s latest regulatory information about chemical constituents.

Joint and several liability- a concept based on the theory that it may not be possible to divide responsibility for the harm caused by hazardous waste equitably among potentially responsible parties (PRP). Joint liability means that more than one defendant is liable to the plaintiff. Several liability means that the plaintiff may choose to sue only one of the defendants and recover the entire amount. One PRP therefore can be held liable for the entire cost of cleanup.

Landfill- a land disposal site for nonhazardous solid wastes.

Leachate- contaminated liquid that results when water collects contaminants as it trickles through wastes, agricultural pesticides or fertilizers. Leachate may then introduce hazardous substances to soil, surface water or groundwater.

Leaching- the process by which soluble chemicals are dissolved and carried down through the soil by water or other fluids (such as gasoline).

Lead- a heavy metal that is hazardous to health if inhaled or swallowed.

LNAPL- Light Non-Aqueous Phase Liquids are organic liquids that are less dense than water and tend to accumulate on top of the water table.

Magnetometry- a geophysical technology used to detect disruptions that metal objects cause in the earth’s localized magnetic field.

Mass Spectrometry- an analytical process by which molecules are broken into fragments to determine the concentration and mass/charge ratio of the fragments.

Medium- air, water or soil, that is the subject of regulatory concern and activities.

Metabolism- A chemical and physical process in which substances (sugar for example) are transformed into energy and waste products by living organisms.

Methane- a colorless, nonpoisonous, flammable gas created by anaerobic decomposition of organic compounds.

Migration pathway- a potential path or route of contaminants from the source of contamination to contact with human populations or the environment. The existence and identification of all potential migration pathways must be considered during assessment and characterization of a waste site.

Micrograms/liter (µ/l) - measure of the concentration of chemicals in fluids. Roughly equivalent to "parts per billion" or ppb.

Milligrams/liter (mg/l)- measure of the concentration of chemicals in fluids. Roughly equivalent to "parts per million" or ppm.

Mobility- ability of contaminants to move. A highly mobile contaminant will spread quickly.

Monitoring- periodic or continuous surveillance or testing to determine the level of compliance with federal, state or local regulations or to assess pollutant levels in various media, or in humans, animals and other living things.

Monitoring well- a well drilled at a specific location on or off a hazardous waste site at which groundwater can be sampled and studied to determine the directions of groundwater flow and the types and quantities of contaminants present in the groundwater.

National Contingency Plan (NCP)- the major regulatory framework that guides the Superfund response effort. The NCP is a comprehensive body of regulations that outlines a step-by-step process for implementing Superfund responses and defines the roles and responsibilities of EPA, other Federal agencies, states, private parties and the communities in response to situations in which hazardous substances are released into the environment.

National Pollutant Discharge Elimination System (NPDES)- the primary permitting program under the Clean Water Act (CWA), which regulates all discharges to surface water. It prohibits discharge of pollutants into waters of the U.S. unless EPA, a state, or a tribal government issues a special permit to do so.

National Priorities List (NPL)- the EPA’s list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial response under Superfund. Only sites on the NPL are eligible for Superfund money.

National Response Center (NRC)- a communications center staffed by the Coast Guard that receives reports of discharges or releases of hazardous substances into the environment. The Coast Guard then relays information about such releases to the appropriate Federal agency.

Natural Attenuation- the use of natural processes to contain the spread of contamination and reduce the amount and concentration of contaminants. Some examples are dilution, volatilization, biodegradation, adsorption and chemical reactions with subsurface materials.

Nonaqueous Phase Liquid (NAPL)- organic substances that do not readily dissolve in water and are a different density than water.

Non-point source- sources of pollution that are diffuse and do not have a point of origin or that are not introduced into a receiving stream from a specific point. For example rainwater runoff from an industrial site is a potential non-point source of pollution.

Nonsaturated soil- soil that is not saturated with water. This is also called the "vadose zone" and is found above the water table.

Operation and Maintenance (O&M)- activities conducted at a site, following remedial actions, to ensure that the cleanup methods are working properly. Activities such as groundwater and air monitoring and inspection and maintenance of treatment equipment remaining onsite are all examples of O&M actions.

Organic- a class of compounds containing mainly carbon, hydrogen and oxygen.

Oxidation- to combine with oxygen or to increase the charge of an ion (e.g., a change from Na+ to Na++)

Ozone- a form of oxygen found naturally that is a chemical oxidant and a major component of smog.

Part per billion (ppb)- one ppb is one one-thousandth of a ppm and is comparable to one-thousandths of a teaspoon of water in a 21ft. diameter and 4 ft. deep swimming pool.

Part per million (ppm)- ppm may be expressed as milligrams per kilogram or milligrams per liter. One ppm is comparable to one teaspoon of water in a 21ft. diameter and 4 ft. deep swimming pool.

Permeability- a measure of the relative ease with which rock, soil or sediment will transmit a fluid (liquid or gas). Sand is very permeable which clay is somewhat permeable.

Phenols- a group of organic compounds that are byproducts of petroleum refining, tanning, textile, and dye and resin manufacturing. Low concentrations may cause taste and odor problems in water, higher concentrations may be harmful to human health or the environment.

Plume- a visible or measurable emission or discharge of a contaminant from a given point of origin into any medium.

Point source- a stationary location or fixed facility from which pollutants are discharged or emitted or any single identifiable discharge point of pollution such as a pipe, ditch or smokestack.

Polynuclear Aromatic Hydrocarbon (PAHs)- a group of chemical compounds that contain more than one fused benzene ring. Commonly found in petroleum fuels, coal products and tar. A benzene ring consists of six carbon atoms attached to each other in a ring.

Porous- full of pores or allows liquids to pass through easily.

Potentially Responsible Party (PRP)- an individual or company (such as owner, operators, transporters, or generators of hazardous waste) that is 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.

Preliminary Assessment and Site Investigation (PA/SI)- process of collecting and reviewing available information about a known or suspected hazardous waste site or release.

Presumptive remedy- a generic treatment option which has been proven effective for a certain class of contaminants with similar site characteristics and are preferred remediation technologies for common CERCLA sites.

Pump and Treat- a general term used to describe remediation methods that involve the pumping of groundwater to the surface for treatment.

Quality Assurance and Quality Control (QA/QC)- a system of procedures, checks, audits, and corrective actions applied to ensure that all EPA research design and performance, environmental monitoring and sampling, and other technical reporting activities are of the highest achievable quality.

Reactivity- a measure of the stability of compound. Reactive wastes are unstable under normal conditions. They may explode or produce toxic fumes and gases when mixed with water.

Record of Decision- a legal, technical and public document that explains which cleanup method will be used at a site. The ROD is based on information and technical analysis generated during the remedial investigation and feasibility study (RI/FS) and consideration of public comments and community concerns.

Release- any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, leaching, dumping or disposing into the environment of a hazardous or toxic chemical or extremely hazardous substance as defined under RCRA.

Remedial Investigation and Feasibility Study (RI/FS)- the RI/FS is the step in the cleanup process that is conducted to gather sufficient information to support the selection of a site remedy that will reduce or eliminate the risks associated with the contamination at the site. The RI involves site characterization (collection of data) and determines if whether the contamination presents a significant risk to human health or the environment. The FS focuses on the development of specific response alternatives for addressing contamination at a site.

Remediate- to correct contamination. This may be accomplished by destroying the contaminants, capping a waste site, excavating and transporting the contaminants to an approved hazardous landfill or any other method which reduces risk at a site.

Removal action- a short-term effort designed to stabilize or clean up a hazardous waste site that poses an immediate threat to human health or the environment. Removal actions include removing tanks or drums of hazardous substances. Removal actions also may be conducted to respond to accidental release of hazardous substances. CERCLA places time and money constraints on the duration of removal actions. Also called Response Action.

RCRA- Resource Conservation and Recovery Act is a Federal law enacted in 1976 that established a regulatory system to track hazardous substances from their generation to their disposal. The law requires the use of safe and secure procedures in treating, transporting, storing and disposing of hazardous substances. RCRA is designed to prevent the creation of new uncontrolled hazardous waste sites.

Risk- a measure of the chance (probability) that damage to life, health, property or the environment will occur.

Risk Assessment- a scientific process that estimates the type and magnitude of risk to human health posed by exposure to chemical substances.

Saturated zone- area beneath the surface of the land in which all openings (pores, cracks) are filled with water.

Semi-volatile- evaporates slower than a volatile compound. See SVOC.

SVOC- Semi-Volatile Organic Compound is a compound containing carbon that does not evaporate as readily as a VOC and has a boiling point greater than 200° C.

Soil boring- a process by which a soil sample is extracted from the ground for chemical, biological, and analytical testing to determine the level of contamination present.

Soil gas- gaseous elements and compounds that occur in the small spaces between particles of the earth and soil.

Solubility- ability of a substance to dissolve in liquid. Sugar is soluble in water but oil is not water-soluble.

Solvent- a liquid capable of dissolving other substances. Solvents are typically organic compounds.

Stakeholder- any party with a vested interest in a remediation project. Government officials, community members, PRPs, banks, etc. are examples of stakeholders.

Strict liability- a concept under CERCLA that allows the Federal government to hold PRPs liable without proving that the PRPs were at fault and without regard to a PRP’s motive. PRP’s can be found liable even if the problems caused by the release of a hazardous substance were unforeseeable, the PRPs acted in good faith, and state-of-the-art hazardous waste management practices were used at the time the materials were disposed of.

Surface Water- all water naturally open to the atmosphere (rivers, lakes, ponds, etc)

Superfund- a trust fund that provides for the cleanup of hazardous substances released into the environment, regardless of fault. The fund was established under CERCLA.

Superfund Amendment and Reauthorization Act (SARA)- a 1986 act amending CERCLA that increased the size of the Superfund trust fund and established a preference for the development and use of permanent remedies and provided new enforcement and settlement tools.

Superfund Innovative Technology Evaluation Program (SITE)- an effort to advance the development, evaluation and commercialization of innovative treatment technologies for assessing and cleaning up hazardous waste sites.

Total Petroleum Hydrocarbon (TPH)- a measure of concentration or mass of petroleum hydrocarbons present in a given amount of air, soil or water.

Threshold Level- the minimum concentration of a substance at which negative health effects begin to appear.

Toxic- acting as a poisonous or hazardous substance; having poisonous or hazardous qualities.

Toxicity- a measure of the poisonous or harmful nature of a substance.

Toxicity Characteristic Leaching Procedure (TCLP)- a test designed to determine the potential for toxic chemicals to move through soils and groundwater. Also used for determining the effectiveness of treatment processes, such as stabilization and solidification, designed to contain wastes or toxic chemicals.

Toxic Substances Control Act (TSCA)- an act which tests, regulates and screens all chemicals produced or imported into the U.S. TSCA requires that any chemical that reaches the consumer marketplace be tested for possible toxic effects prior to commercial manufacture. Any existing chemical that poses health and environmental hazards is tracked and reported under TSCA.

Toxicology- the study of adverse effects of chemicals on living organisms.

Trichloroethylene (TCE)- a stable, low-boiling colorless liquid that is used as a solvent and metal degreaser.

Unsaturated zone- area between the surface and the water table (also called the vadose zone).

Vadose zone- layer of unsaturated soil above the water table (also called the vadose zone).

Vapor- gaseous phase of any substance that is liquid or solid at atmospheric pressures and temperatures. For example, steam is a vapor.

Vaporized- to go from the liquid to gaseous state.

VOC-volatile organic compound is an organic compound that evaporates easily, such as paint thinner.

Volatile- a substance that is readily evaporated.

Wastewater- spent or used water from an individual home, community, farm or an industry that contains dissolved or suspended substances.

Water Table- boundary between the saturated and unsaturated zones beneath the surface of the earth.

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The Midwest Hazardous Substance Research Center, Michigan State University.
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