Federal approach to contaminated sites: glossary of terms

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Adverse Effect

An undesirable or harmful effect to an organism, indicated by some result such as mortality, altered food consumption, altered body and organ weights, altered enzyme concentrations or visible pathological changes.


The philosophy and procedures used by a regulatory agency to establish environmental quality criteria. The components of the approach can include the types of information considered, the management goal underlying the criteria, relative priorities assigned to various types of information and the ways that information is combined to set the criteria.



An area not influenced by chemicals released from the site under evaluation.

Background Concentration

The concentration of a chemical substance occurring in media removed from the influence of industrial activity at a specific site and in an area considered to be relatively unaffected by industrial activity.


The measured value obtained when a specific component of the sample is not present.



The removal of a chemical substance or hazardous material from the environment to prevent, minimize or mitigate damage to public health, safety or welfare, or the environment, that may result from the presence of the chemical substance or hazardous material. The clean-up is carried out to specified clean-up criteria.


The amount of chemical or substance in a given environmental medium.

Conceptual Model

Our idealization of a hydrogeological system on which we can base a mathematical model. The conceptual model includes assumptions on the hydrostratigraphy, material properties, dimensionality, and governing processes.


Any physical, chemical, biological or radiological substance in air, soil or water that has an adverse effect. Any chemical substance whose concentration exceeds background concentrations or which is not naturally occurring in the environment.

Contaminated Site

A contaminated site is defined as a site at which substances occur at concentrations: (1) above background levels and pose or are likely to pose an immediate or long-term hazard to human health or the environment, or (2) exceeding levels specified in policies and regulations.


The introduction into soil, air or water of a chemical, organic or radioactive material or live organism that will adversely affect the quality of that medium.


Numerical standards that are established for the concentrations of chemical substances in soil, groundwater, surface water, and sediments that relate to the suitability of a site for specific land uses and land use categories. Criteria are also often referred to as guidelines.



The closure of an industrial facility followed by the removal of process equipment, buildings and structures.


Ecological Risk Assessment

The process of defining and quantifying risks to non-human biota and determining the acceptability of those risks.

Environmental Site Assessment (ESA)

A systematic due diligence process that includes studies, services and investigations to plan, manage and direct assessment, and decommissioning and clean-up actions.


The contact between a contaminant and an individual or population.

Exposure Pathway

The route by which a receptor comes into contact with a contaminant. Exposure pathways include ingestion, dermal absorption or inhalation.


Generic Criteria

Numerical values for the concentration of chemical substances in soil, groundwater, surface water and sediments considered safe for a broad range of receptors, site conditions and regions under defined land uses.


All subsurface water that occurs beneath the water table in rocks and geologic formations that are fully saturated.

Guideline-Based Approach

The remediation of a site to generic soil, groundwater, sediment and surface water criteria developed by federal or provincial or other regulatory authorities. Under this method, established environmental quality guidelines are adopted "as is" as the site-specific remediation objectives.



The adverse impact on health or property which results from the presence of or exposure to a substance. The significance of the adverse effect depends on the nature and severity of the hazard and the degree to which the effect is reversible.

Human Health Assessment

The process of defining and quantifying risks and determining the acceptability of those risks to humans.



The fundamental components of the environment including water, sediment, soil and biota.


The movement of chemicals, bacteria and gases in flowing water or vapour in the subsurface.


A conceptual, mathematical or physical system intended to represent a real system. The behaviour of a model is used to understand processes in the physical system to which it is analogous.


Observing the change in geophysical, hydrogeological or geochemical measurement with time.

Monitoring Well

A well that is used to extract groundwater for physical, chemical or biological testing, or to measure water levels.


Natural Environment

The air, land and water, or any combination or part thereof.



A numerical limit or narrative statement that has been established to protect and maintain a specified use of soil or water at a particular site by taking into account site-specific conditions. The numerical limits or narrative statement that are established to protect and maintain the specified uses of water, sediment or soil at a particular site. Objectives may be adopted from generic criteria or formulated to account for site-specific conditions.



The route along which a chemical substance or hazardous material moves in the environment Permafrost. Perennially frozen ground in areas where the temperature remains at or below 0°C for two or more years in a row.



The person or organisms, including plants, subjected to chemical exposure.

Remedial Action Plan

A plan to bring about the restoration or clean-up of a site.


The improvement of a contaminated site to prevent, minimize or mitigate damage to human health or the environment. Remediation involves the development and application of a planned approach that removes, destroys, contains or otherwise reduces the availability of contaminants to receptors of concern.

Remediation Criteria

Numerical limits or narrative statements pertaining to individual variables or substances in water, sediment or soil which are recommended to protect and maintain the specific use of contaminated sites. When measurements taken at a contaminated site indicate that the remediation criteria are being exceeded, the need for remediation is indicated.


Improvement of the quality of, remediation, clean-up, or other management of soil, groundwater or sediment so that the site will be suitable for the intended use.

Risk Assessment

The scientific examination of the nature and magnitude of risk to define the effects on both human and other receptors of the exposure to contaminant(s).

Risk-Based Approach

An approach based on a detailed evaluation of hazard and exposure potential at a particular site. Risk assessment is an important tool to use where, for example, national criteria do not exist for a contaminant, where clean-up to guideline-based criteria is not feasible for the targeted land use, where guidelinebased objectives do not seem appropriate given the site-specific conditions, where significant or sensitive receptors of concern have been identified or where there is significant public concern, as determined by the lead agency.

Risk Management

The selection and implementation of a strategy of control of risk, followed by monitoring and evaluation of the effectiveness of that strategy. Risk management may include direct remedial actions or other strategies that reduce the probability, intensity, frequency or duration of the exposure to contamination. The latter may include institutional controls such as zoning designations, land use restrictions, or orders. The decision to select a particular strategy may involve considering the information obtained from a risk assessment. Implementation typically involves a commitment of resources and communication with affected parties. Monitoring and evaluation may include environmental sampling, post-remedial surveillance, protective epidemiology, and analysis of new health risk information, as well as ensuring compliance.


Saturated Zone

The zone where voids in the soil or rock are filled with water at greater than atmospheric pressure. In an unconfined aquifer, the water table forms the upper boundary of the saturated zone.


A rapid analysis to determine if further action (e.g. detailed analysis or clean-up) is warranted.

Site Management/Remediation Strategy

The implementation of a strategy or measures to control or reduce the level of risk estimated by the risk assessment.

Site-Specific Clea-up Criteria

Numerical values for the concentration of chemical substances in soil, groundwater, surface water, and sediments that relate to the suitability of a site for specific land uses and land use categories.

Site-Specific Remediation Objective

The process of applying environmental quality guidelines at the site level to establish remediation or clean-up targets for the site. Site-specific remediation objectives may be adopted from existing guidelines (generic criteria), modified from existing guidelines, or developed using a risk assessment approach.

Soil Gas

The vapour or gas that is found in the unsaturated zone.

Surface Water

Natural water bodies, such as rivers, streams, brooks and lakes, as well as artificial water courses, such as irrigation, industrial and navigational canals, in direct contact with the atmosphere.


Test Pit

A shallow pit, made using a backhoe, to characterize the subsurface.


The production of any type of damage, permanent or temporary, to the structure or functioning of any part of the body. The conditions of exposure under which toxic effects are produced - the size of the dose and the duration of the dosing needed - vary greatly among chemicals.


Water Table

The upper limit of the saturated zone. It is measured by installing wells that extend a few feet into the saturated zone and then recording the water level in those wells.

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