Terminology Services

Hazard Ranking System Glossary

Long Name:

Hazard Ranking System Glossary of Terms and Acronyms

Description:

Glossary of Hazard Ranking System Training Course.

Publishing Organization:

Office of Land and Emergency Management/Office of Superfund Remediation and Technology Innovation (OSRTI)

Last Update:

December 22, 2022

Program Site:

https://www.epa.gov/superfund/superfund-cleanup-support

Terms & Acronyms

Search Terms

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	Term
	Actual Contamination for a Drinking Water Intake	Definition: Drinking water intake located in a portion of a surface water body that meets the criteria for an observed release.
	Actual Contamination for the Surface Water Pathway	Definition: A portion of a surface water body is considered subject to actual contamination if it meets criteria for an observed release. Sampling data from aqueous, sediments, or essentially sessile, benthic organisms may be used to establish actual contamination. However, the requirements for establishing actual contamination vary by threat.
	Actual Contamination in the Air Migration Pathway	Definition: A target population is subject to actual contamination if a sample location within its distance category meets the criteria for an observed release. Targets located within distance categories closer to the source than the distance category where the observed release is established are also subject to actual contamination. Targets located within distance categories beyond the most distant category containing an observed release, but within the 4 - mile target distance limit, are subject to potential contamination.
	Actual Contamination in the Ground Water Pathway	Definition: A drinking water well is subject to actual contamination if a sample from the well meets the criteria for an observed release. The scorer cannot infer actual contamination of a drinking water well based on other samples (e.g., from downgradient wells).
	Adequately Determined (for purposes of Tier A only)	Definition: The total mass of all CERCLA hazardous substances in the source and releases from the source (or for the area of observed contamination) is known or is estimated with reasonable confidence. (For the site hazardous waste quantity factor value to be adequately determined for Tier A, this definition must apply for all sources.)
	Adequately Determined (for purposes of Tier B only)	Definition: The total mass of all hazardous wastestreams and CERCLA pollutants and contaminants for the source and releases from the source (or for the area of observed contamination) is known or is estimated with reasonable confidence. (For the site hazardous waste quantity to be adequately determined for Tier B, this must apply for all sources.)
	Ambient aquatic life advisory concentration	Acronym: AALAC
	Ambient water quality criteria	Acronym: AWQC
	Annual Use	Definition: Criterion for determining whether a standby intake may be used to evaluate the nearest intake factor. To meet this criterion, a standby intake generally should supply drinking water for at least one 24 - hour period in a year.
	Aquatic Human Food Chain Organism	Definition: Aquatic species directly consumed by humans, including certain finfish, shellfish, crustaceans, amphibians, and amphibious reptiles.
	Aquatic Vertebrate Species	Definition: Vertebrate species that lay eggs or bear young in water. Included are all fishes, nearly all amphibians, and a few mammals (i.e., manatees, whales, porpoises). Note that most species of toads and salamanders and many species of frogs spend most of their adult lives on land, but most species return to water to breed.
	Aquifer	Definition: One or more strata of rock or sediment that is saturated and sufficiently permeable to yield economically significant quantities of water to wells or springs. An aquifer includes any geologic material that is currently used or could be used as a source of water (for drinking or other purposes) within the target distance limit. All geologic materials combined into one aquifer are referred to as a single hydrologic unit.
	Aquifer Boundary	Definition: A physical barrier to ground water flow identified as the contact between geologic materials defined as an aquifer and materials defined as non - aquifer (or as an aquifer but with a significantly lower hydraulic conductivity). (Where interconnections between aquifers are documented, aquifer boundaries are expanded to encompass the interconnected aquifers.)
	Aquifer Discontinuities	Definition: Geologic and hydrologic features or structures that entirely transect an aquifer (or multiple aquifers, if interconnected) and that are expected to disrupt and/or prevent the flow of ground water and hazardous substances across the feature or structure. Aquifer discontinuities are a type of aquifer boundary.
	Aquifer Interconnections	Definition: Subsurface conditions that allow two or more aquifers separated by aquifer boundaries to be combined into a single aquifer; subsurface conditions must demonstrate that the aquifer boundaries separating the aquifers do not or would not impede the flow of ground water and hazardous substances between the aquifers. Aquifer interconnections are evaluated within two miles of the site and in areas underlying contamination attributable to the site.
	Area of Observed Contamination	Definition: Evaluated only in the soil exposure pathway and established based on sampling locations as follows: (1) Generally, for contaminated soil, consider the sampling locations that indicate observed contamination and the area lying between such locations to be an area of observed contamination, unless information indicates otherwise. (2) For sources other than contaminated soil, if any sample taken from the source indicates observed contamination, consider the entire source to be an area of observed contamination. (3) If an area of observed contamination (or a portion of such an area) is covered by a permanent, or otherwise maintained, essentially impenetrable material (e.g., asphalt), exclude the covered area from the area of observed contamination. However, asphalt or other impenetrable materials contaminated by site - related hazardous substances may be considered areas of observed contamination. Acronym: AOC
	Associated Containment Structures	Definition: As used in HRS Table 3 - 2, constructed barriers (e.g., liners, dikes, berms) that may have been placed under, over, or around a hazardous substance source (e.g., a landfill or a waste pile) to prevent the release of hazardous substances to the environment.
	Attribution	Definition: Attribution usually requires documenting that (1) at least one hazardous substance found in a release at a concentration significantly above background (or directly observed in the release) was produced, stored, deposited, handled, or treated at the site; and (2) at least a portion of the significant increase could have come from a source at the site.
	Background Level	Definition: The concentration of a hazardous substance that provides a defensible reference point with which to evaluate whether or not a release from the site has occurred. The background level should be reflective of the concentration of the hazardous substance in the medium of concern for the environmental setting on or near a site. Background level does not necessarily represent pre - release conditions, nor conditions in the absence of influence from source(s) at the site. Background level may or may not be less than the detection limit, but if it is greater than the detection limit, it should account for variability in local concentrations. Background level need not be established by chemical analysis.
	Background Sample	Definition: A sample used in establishing a background level.
	Below - ground Tank	Definition: A tank with its entire surface area below the surface and not visible; however, a fraction of its associated piping may be above the surface.
	Benthic Organisms	Definition: Organisms that live on or at the bottom (i.e., not in the water column) of water bodies for most of their adult life cycle, such as clams, lobsters, and crayfish.
	Bioaccumulation Potential	Definition: Evaluates the tendency for a substance to accumulate in the tissue of an aquatic human food chain organism and forms one component of the toxicity/persistence/bioaccumulation and toxicity/mobility/persistence/bioaccumulation factors within the human food chain threat - waste characteristics factor category.
	Bioaccumulation potential factor	Acronym: BPF
	Bioaccumulation potential factor value	Definition: BPFV is a measure based on a hierarchy of three types of data: bioconcentration factor; n - octanol - water partition coefficient (Kow); and water solubility. Bioaccumulation potential factor value reflects the tendency for a substance to accumulate in the tissue of an aquatic organism C the greater the bioaccumulation potential factor value, the greater the relative tendency of a substance to accumulate. Bioaccumulation potential factor values for commonly encountered hazardous substances are listed in SCDM. Acronym: BPFV
	Bioconcentration Factor	Acronym: BCF
	Blended Water Distribution System	Definition: A drinking water supply system which can or does combine (e.g., via connecting valves) water from more than one well or surface water intake, or from a combination of wells and intakes.
	Brackish Water	Definition: Water with an average tidal cycle chloride concentration of greater than 250 mg/l but less than 18,700 mg/l (corresponding to greater than 0.45 but less than 34 parts per thousand).
	Bulk liquids	Definition: Noncontainerized liquids deposited directly into a source by pipe, tanker truck, or other means of transport.
	Buried/Backfilled Surface Impoundment	Definition: A surface impoundment that has been completely covered with soil or other cover material after the final deposition of waste materials.
	Burn Pit	Definition: An uncovered area on the land surface that is not presently burning but that was at one time used to burn hazardous substances or was otherwise significantly inflamed.
	Capacity	Definition: The amount of water a well or intake can deliver to a water distribution system. Capacity may be expressed in units that are equivalent to a pumpage rate or as a percentage of the system's requirements.
	CERCLA Hazardous Substances	Definition: Hazardous substance as defined by statute in CERCLA section 101(14); the list of CERCLA hazardous substances having reportable quantities is found in 40 CFR 302 in Table 302.4.
	CERCLA Pollutant or Contaminant	Definition: Section 101(33) of CERCLA states that: "pollutant or contaminant shall include, but not be limited to, any element, substance, compound, or mixture, including disease - causing agents, which after release into the environment and upon exposure, ingestion, inhalation, or assimilation into any organism, either directly from the environment or indirectly by ingestion through food chains, will or may reasonably be anticipated to cause death, disease, behavioral abnormalities, cancer, genetic mutation, physiological malfunctions (including malfunctions in reproduction) or physical deformations, in such organisms or their offspring; except that the term "pollutant or contaminant" shall not include petroleum, including crude oil or any fraction thereof which is not otherwise specifically listed or designated as a hazardous substance under subparagraphs (A) through (F) of paragraph (14) and shall not include natural gas, liquefied natural gas, or synthetic gas of pipeline quality (or mixtures of natural gas and such synthetic gas)."
	Chemical Waste Pile	Definition: A pile consisting primarily of discarded chemical products (whether marketable or not), by - products, radioactive wastes, or used or unused feedstocks.
	Closed Fishery	Definition: A fishery closed or restricted by a government entity. Such closure prohibits fishing for commercial, recreational, or subsistence purposes. To be evaluated for the HRS, closure must be site - related.
	Commercial Agriculture	Definition: Production of crops for sale, including crops intended for widespread distribution (e.g., supermarkets) and more limited distribution (e.g., local produce stands), and any nonfood crops such as cotton and tobacco. Commercial agriculture does not include livestock production, livestock grazing, or crops grown for household consumption (e.g., backyard garden or fruit trees).
	Commercial Aquaculture	Definition: Cultivation of fish or shellfish to be sold for widespread distribution. Examples include a rearing pond used to raise catfish or a pond for nonfood crops such as goldfish and tropical fish.
	Commercial Fishing	Definition: Fishing to derive income from catching and selling organisms taken from fresh or salt waters.
	Commercial Food Crops	Definition: Crops that are intended to be sold widely, such as in supermarkets, and locally, such as those sold at local produce stands. Crops grown for domestic consumption or for use in a single restaurant are not considered commercial food crops.
	Commercial Forage Crops	Definition: Crops grown to be sold as food for livestock (it is not necessary to document that these crops were sold only for commercial livestock); and grasslands used for grazing by commercial livestock (including some areas technically defined as "pasture/rangeland" by the USDA).
	Commercial Livestock	Definition: Livestock raised for sale to commercial wholesalers or supermarkets. Livestock raised for private or domestic use is not considered commercial livestock.
	Commercial Livestock Production or Commercial Livestock Grazing	Definition: Raising or feeding of livestock for sale (e.g., chicken coop used for housing commercially sold poultry, pastureland used for grazing on a commercial farm.)
	Commercial Silviculture	Definition: Cultivation of trees for sale (e.g., Christmas tree farm, trees raised for lumber).
	Comprehensive Environmental Response, Compensation, and Liability Act	Acronym: CERCLA
	Comprehensive Environmental Response, Compensation, and Liability Information System	Acronym: CERCLIS
	Confining Layer	Definition: A layer of low hydraulic conductivity (relative to adjacent geologic materials) that is not expected to be used as an aquifer.
	Container or Tank	Definition: (1) Any stationary device constructed primarily of nonearthen materials (such as wood, concrete, steel, or plastic) used to contain an accumulation of a hazardous substance; or (2) any portable device in which a hazardous substance is stored or otherwise handled.
	Contaminated Soil (excluding land treatment)	Definition: Soil onto which available evidence indicates a hazardous substance was spilled, spread, disposed, or deposited.
	Contiguous With Regard to Wetlands	Definition: Hydraulic connection (constructed or natural) between other surface water bodies and the wetland that allows water to move between the other surface water bodies and the wetland. Evidence to support an assertion that a wetland is contiguous to another surface water body includes (but is not limited to): (1) Wetland is in the annual floodplain of the other surface water body; (2) Wetland is supplied by the water body via a natural or constructed channel; or (3) Water flows between the other surface water to the wetland via seepage or ground water.
	Contour Line	Definition: Line that connects points of equal elevation on a topographic map; contour lines are colored brown on USGS topographic maps.
	Contract Laboratory Program	Definition: The analytical program developed for CERCLA waste site samples to fill the need for legally defensible analytical results supported by a high level of quality assurance and documentation. Acronym: CLP
	Contract - Required Detection Limit	Definition: For HRS purposes, a term equivalent to the contract - required quantitation limit (CRQL), but used primarily for inorganic substances. Acronym: CRDL
	Contract - Required Quantitation Limit	Definition: The substance - specific level that a CLP laboratory must be able to routinely and reliably detect in specific sample matrices. The CRQL is not the lowest detectable level achievable, but rather the level that a CLP laboratory must reliably quantify. The CRQL may or may not be equal to the quantitation limit of a given substance in a given sample. For HRS purposes, the term CRQL also refers to the contract - required detection limit (CRDL). Acronym: CRQL
	Dense non - aqueous phase liquid	Acronym: DNAPL
	Designated for Drinking Water Use	Definition: Section 305(a) of the Clean Water Act requires states to prepare a water quality inventory that designates and classifies certain waters for drinking water use. The water can have such a classification even if it is not currently used for or is not currently suitable to be used for drinking water.
	Detection Limit	Definition: The lowest quantity of a hazardous substance that can be distinguished from the normal random "noise" of an analytical instrument or method. For HRS purposes, DL is the method detection limit (MDL) or, for real - time field instruments, the instrument detection limit (IDL) as used in the field. Acronym: DL
	Dilution Weight	Definition: A unitless parameter that adjusts the assigned point value for certain targets subject to potential contamination as a function of the flow or depth of the water body at the target. For the drinking water threat, use HRS Table 4 - 14 to assign a dilution - weighted population.
	Direction of Overland Flow	Definition: Determined on a topographic map by drawing flow lines perpendicular to contour lines. Direction of flow will normally be along these flow lines, from areas of higher elevation towards areas of lower elevation but can be affected by man - made barriers such as walls and sewers. The determination of flow direction is important for identifying the drainage area upgradient of sources at the site and for identifying the overland segment of the hazardous substance migration path.
	Drainage Area	Definition: The area upgradient of a source contributing water to the source via overland flow; this area is based on topography, except where overland flow is captured and/or diverted (e.g., storm sewers, run - on control features, walls) around the source. In cases where upland flow is captured or diverted, only the area of the source and areas upgradient of the source between the source and the device or structure diverting overland flow from the source are included in the drainage area.
	Drum	Definition: A type of container used to hold hazardous substances. For HRS purposes, drums are standard 55 - gallon cylindrical containers.
	Ecological - based Benchmarks	Definition: Reference data by which the level of contamination of sensitive environments is evaluated within the environmental threat - targets factor category.
	Ecosystem Bioaccumulation Potential	Definition: Ecosystem bioaccumulation potential evaluates the tendency for a substance to accumulate in the tissue all aquatic organisms, not just human food chain organisms (as in bioaccumulation potential), and forms one component of the ecosystem toxicity/persistence/bioaccumulation and ecosystem toxicity/mobility/persistence/bioaccumulation factors within the environmental threat - waste characteristics factor category. HRS Table 4 - 15 and sections 4.1.3.2.1.3 and 4.1.4.2.1.3 provide the data hierarchy to follow when evaluating bioaccumulation potential.
	Ecosystem Toxicity	Definition: The toxicity of a substance to aquatic organisms. It forms one component of the ecosystem toxicity/persistence/bioaccumulation and ecosystem toxicity/mobility/persistence/bioaccumulation factors within the environmental threat - waste characteristics factor category. HRS Table 4 - 19 provides the data hierarchy to follow when evaluating ecosystem toxicity.
	Environmental Protection Agency	Acronym: EPA
	Essentially Impervious Base	Definition: A base underlying containers that is free from cracks and gaps and prevents penetration of leaks, spills, or precipitation.
	Essentially Sessile Benthic Organisms	Definition: Organisms that essentially stay at or near a localized spot in a water body during the adult stage of their life cycle (e.g., barnacles, oysters, muscles, sponges, and stalked diatoms). These organisms may not live on the bottom, but must not live suspended in the water column. They may be attached to rocks, pilings, or submerged banks at or near the surface. Samples from these organisms should be limited to the adult forms and can be used in the HRS for two purposes: 1.To establish an observed release (use any essentially sessile benthic organism); and 2.To establish actual contamination and the level of contamination (use only human food chain organisms).
	Evidence of Hazardous Substance Migration	Definition: Chemical analyses and/or visual evidence that demonstrate hazardous substances attributable to a source have migrated away from that source into the surrounding soil, ground water, surface water, or air (e.g., leachate containing hazardous substances coming out of the source; stained or contaminated soil that can be attributed to migration from the source; evidence of the overflow from a surface impoundment containing hazardous substances).
	Fishery	Definition: Any area of a surface water body from which human food chain organisms are taken or could be taken for human consumption on a commercial, recreational, or subsistence basis. Food chain organisms include fish, shellfish, crustaceans, amphibians, and amphibious reptiles. Fisheries are delineated by changes in dilution weights, level of contamination, or annual production.
	Flow Rate	Definition: The long - term average annual discharge of a river or stream (i.e., the annual discharge averaged over many years of record).
	Food and Drug Administration advisory levels	Acronym: FDAAL
	Free Liquids	Definition: Liquids that readily separate from the solid portion of a substance under ambient temperature and pressure.
	Freeboard	Definition: Vertical distance between the top of a tank or surface impoundment dike and the surface of the hazardous substance contained therein. Freeboard is intended to prevent overtopping resulting from normal or abnormal operations, wind and wave action, rainfall, and/or run - on.
	Fresh Water	Definition: Water with an average tidal cycle chloride concentration of 250 mg/l or less (corresponding to salinity of 0.45 parts per thousand).
	Functioning Ground Water Monitoring System	Definition: A system of test wells installed around a source to detect migration of hazardous substances. In evaluating the containment factor in the ground water pathway, the emphasis is on the functioning of the monitoring system. Thus, wells that are not sampled or maintained do not constitute a functioning ground - water monitoring system.
	Geographic Information System	Acronym: GIS
	Ground water	Acronym: GW
	Hazard Ranking System	Acronym: HRS
	Hazard Ranking System Guidance Manual	Acronym: HRSGM
	Hazardous Constituent Quantity	Definition: The mass (in pounds) of CERCLA hazardous substances allocated to a source (with certain exceptions for RCRA wastes).
	Hazardous Substance Migration Path	Definition: The path that hazardous substances travel (or would travel) overland from a source to surface water (overland segment) and within surface water to the target distance limit (in - water segment). In certain cases (e.g., sites consisting only of contaminated sediments, sites where sources are located in surface water bodies), the hazardous substance migration path consists of only an in - water segment.
	Hazardous Substances	Definition: Hazardous substances consist of CERCLA hazardous substances, pollutants, and contaminants as defined in CERCLA sections 101(14) and 101(33), except as otherwise specifically noted in the HRS.
	Hazardous waste quantity	Acronym: HWQ
	Hazardous Waste Quantity Factor Value	Definition: An assigned value for the pathway that is based on the sum of all source hazardous waste quantity values, and assigned using HRS Table 2 - 6.
	Hazardous Wastestream	Definition: Material containing CERCLA hazardous substances as defined in CERCLA section 101(14), that was deposited, stored, disposed, or placed in, or that otherwise migrated to, a source. Acronym: Bioaccumulation potential factor
	Human food chain	Acronym: HFC
	In - water Segment	Definition: Portion of the hazardous substance migration path from the probable point of entry (PPE) to the target distance limit. For tidally - influenced rivers, the in - water segment may include portions of surface water bodies upstream from the PPE to the extent that the in - water migration path is reversed by tides. For contaminated sediments with no identified source, the in - water segment begins at the upstream boundary (for streams and rivers) or center of the area of contaminated sediments (for water bodies with no direction of flow).
	Ingredient in Commercial Food Preparation	Definition: Surface water used for wholesale food preparation falls into this category (e.g., a manufacturer that prepares food products to be sold in supermarkets or produce stands). Food prepared in restaurants is not included in this category.
	Instrument detection limit	Acronym: IDL
	Intermittent Water Body	Definition: Water bodies that do not contain water throughout the year under normal conditions.
	Karst	Definition: A kind of terrain with characteristics of relief and drainage arising from a high degree of rock solubility. The majority of karst conditions occur in limestone areas, but karst may also occur in areas of dolomite, gypsum, or salt deposits. Features associated with karst terrain may include irregular topography, abrupt ridges, sinkholes, caverns, abundant springs, disappearing streams, and the lack of a well - developed surface drainage system of tributaries and streams.
	Land Treatment Zone	Definition: Soil layer in the unsaturated zone of a land treatment unit within which hazardous substances are intended to be degraded, transformed, or immobilized.
	Landfarm/Land Treatment	Definition: A method of waste management in which liquid wastes or sludges are spread over land and tilled or liquids are injected at shallow depths into soils.
	Landfill	Definition: An engineered (by excavation or construction) or natural role in the ground into which wastes have been disposed of by backfilling or contemporaneous deposition of soil and wastes.
	Layer of Lower Relative Hydraulic Conductivity	Definition: A geologic material with lower hydraulic conductivity than adjacent geologic materials. If used to establish aquifer boundaries, the difference in hydraulic conductivity should be at least two orders of magnitude.
	Level I Concentration for the Surface Water Pathway	Definition: Level I concentrations are established in samples in which the concentration of a hazardous substance that meets the criteria for an observed release is at or above its specific health - based benchmark for the surface water threats, with certain exceptions for the human food chain threat. Targets also may be subject to Level I concentrations if multiple hazardous substances that meet the criteria for an observed release are present below their respective benchmarks but the I or J index is greater than or equal to one. Benchmarks for the surface water pathway include maximum contaminant level (MCLs), non - zero maximum contaminant level goals (MCLGs), Food and Drug Administration advisory levels (FDAAL) for fish or shellfish, ambient water quality criteria (AWQC) for protection of aquatic life, ambient aquatic life advisory concentrations (AALAC), and screening concentrations for cancer and chronic non - cancer effects.
	Level I Concentrations for the Air Migration Pathway	Definition: Level I concentrations are established at sampling locations where the concentration of at least one hazardous substance that meets the criteria for an observed release is at or above its health - based benchmark for air. Level I concentrations also may be established if multiple hazardous substances are present below their respective benchmarks, but the I or J index is greater than or equal to one. Benchmarks for air include National Ambient Air Quality Standards (NAAQs), National Emission Standards for Hazardous Air Pollutants (NESHAPs), screening concentrations for cancer, and screening concentrations for noncancer toxicological responses.
	Level I Concentrations for the Drinking Water Threat	Definition: Level I concentrations are established in aqueous samples in which the concentration of at least one hazardous substance that meets the criteria for an observed release and is present at or above its drinking water benchmark. A drinking water intake also may be subject to Level I concentrations if multiple hazardous substances that meet the criteria for observed release are present below their respective benchmarks, but the I or J index is greater than or equal to one.
	Level I Concentrations for the Environmental Threat	Definition: Level I concentrations are established in samples in which the concentration of at least one hazardous substance meets the criteria for an observed release and is present at or above the appropriate ecological - based benchmark level (i.e., the appropriate EPA ambient water quality criteria (AWQC) or EPA ambient aquatic life advisory concentrations (AALAC) for the substance). Because AWQC and AALAC apply only to surface water samples, Level I concentrations can only be established based on aqueous samples. The I and J indices (see HRS section 2.5.2) do not apply because there are no screening concentration benchmarks for sensitive environments.
	Level I Concentrations for the Ground Water Pathway	Definition: Level I concentrations are established for samples from drinking water wells in which the concentration of a hazardous substance that meets the criteria for an observed release is at or above its specific health - based benchmark. A drinking water well also may be subject to Level I concentrations if multiple hazardous substances that meet the observed release criteria are present below their respective benchmarks, but the I or J index is greater than or equal to one. Benchmarks for the ground water include maximum containment levels (MCLs), nonzero maximum containment level goals pathway (MCLGs), and screening concentrations for cancer and chronic noncancer effects.
	Level I Concentrations for the Human Food Chain Threat	Definition: Level I concentrations are established for tissue samples from aquatic human food chain organisms in which the concentration of a hazardous substance that meets the criteria for an observed release is at or above its specific health - based benchmarks. The tissue sample must also be taken from within the boundaries of the area of actual contamination. Aqueous and sediment sample results cannot be used to establish Level I concentrations for this threat.
	Level II Concentration for the Surface Water Pathway	Definition: Level II concentrations are established in samples in which the concentration of at least one hazardous substance meets the criteria for an observed release, but the conditions for Level I concentrations are not met, with certain exceptions for the food chain threat. In addition, Level II concentrations are assigned to observed releases established by direct observation.
	Level II Concentrations for the Air Migration Pathway	Definition: Level II concentrations are established at sampling locations where the concentration of at least one hazardous substance meets the criteria for an observed release, but the conditions for Level I concentrations are not met. In addition, Level II is assigned to observed releases established by direct observation.
	Level II Concentrations for the Drinking Water Threat	Definition: Level II concentrations are established for samples in which the concentration of at least one hazardous substance meets the criteria for an observed release, but the conditions for Level I concentrations are not met. In addition, Level II concentrations are assigned to observed releases established by direct observation.
	Level II Concentrations for the Environmental Threat	Definition: Level II concentrations are established for samples in which the concentration of at least one hazardous substance meets the criteria for an observed release, but the conditions for Level I concentrations are not met. In addition, Level II is assigned for observed releases that are based on direct observation.
	Level II Concentrations for the Ground Water Pathway	Definition: Level II concentrations are established for samples from drinking water wells in which the concentration of at least one hazardous substance meets the observed release criteria, but the conditions for Level I are not met. In addition, Level II is assigned to observed releases established by direct observation.
	Level II Concentrations for the Human Food Chain Threat	Definition: Level II concentrations are established in aqueous samples, sediment samples, or tissue samples from essentially sessile benthic organisms in which the concentration of hazardous substances meet the criteria for an observed release, but the conditions for Level I concentrations are not met. In addition, Level II concentrations are assigned to observed releases established by direct observation.
	Light non - aqueous phase liquid	Acronym: LNAPL
	Likelihood of release	Acronym: LR
	Liner	Definition: A continuous barrier that covers all the earth likely to be in contact with a source so that hazardous substances or leachate containing hazardous substances would not migrate to the surrounding earth. The barrier may be synthetic material (e.g., a thick, continuous polyethylene membrane) or engineered, compacted natural material (e.g., re - worked and low permeability clay). However, an in - situ clay layer that has not been re - engineered by compaction or other methods is not considered a liner.
	Listed Sensitive Environment	Definition: Areas that are evaluated as one or more of the sensitive environments listed in HRS Table 4 - 23, even if these areas (or portions of these areas) also are being evaluated as a wetland. The distinction is necessary because a wetland that is also a listed sensitive environment (e.g., a wetland area that also is habitat known to be used by an endangered species) would be evaluated as two separate sensitive environments. Point values are assigned differently for wetlands than for the other types of sensitive environments.
	Maintained Engineered Cover	Definition: Vegetated cover, usually made of compacted clean soil. It is generally placed over a source at its closure and is designed and constructed to minimize the migration of liquids through the closed source, function with minimum maintenance, and accommodate settling and subsidence. Maintenance of the integrity and effectiveness of the final cover may include repairing the cap as necessary to correct the effects of settling, subsidence, erosion, and other events.
	Major or Designated Water Recreation Area	Definition: A major water recreation area is an area used by a large number of people for recreational purposes (e.g., a water theme park). A designated water recreation area is an area designated and maintained by a government body (e.g., local, state, or Federal) as an area for public water recreation (e.g., municipal swimming pool).
	Maximum containment level goals	Acronym: MCLGs
	Maximum containment levels	Acronym: MCLs
	Maximum contaminant level	Acronym: MCL
	Maximum contaminant level goal	Acronym: MCLG
	Method Detection Limit	Definition: The lowest concentration of a hazardous substance that a method can detect reliably in either a sample or blank. Acronym: MDL
	Multiple-aquifer System	Definition: A hydrogeological situation consisting of two or more aquifers that are not interconnected and that underlie sources at the site.
	National Ambient Air Quality Standard	Acronym: NAAQS
	National Contingency Plan	Acronym: NCP
	National Emission Standard for Hazardous Air Pollutants	Acronym: NESHAP
	National Pollution Discharge Elimination System	Acronym: NPDES
	National Priorities List	Acronym: NPL
	National Wetlands Inventory	Acronym: NWI
	Nearby Individual	Definition: Resident or student with the shortest travel distance to any area of observed contamination. If one or more individuals meet the criteria for resident individual, the nearby individual factor value is zero.
	Nearby Population	Definition: Total number of people who live or attend school within a one-mile travel distance of an area of observed contamination and who do not meet the criteria for resident individual.
	Nearest Intake Factor	Definition: Factor for evaluating the maximally exposed intake. This factor is based on the presence of actual contamination or, for watersheds where no intake is subject to actual contamination, the flow or depth of the water body at the intake nearest to the probable point of entry within the target distance limit. This factor receives a value from 0 to 50.
	Nearest Well Factor	Definition: Factor for evaluating the maximally exposed well. This factor is based on the presence of actual contamination or, for aquifers where no target drinking water well is subject to actual contamination, presence of karst and distance to nearest drinking water well. This factor receives one of nine discrete values from 0 to 50.
	Nuclear Regulatory Commission	Acronym: NRC
	Observed Contamination	Definition: Observed contamination is established for the soil exposure pathway only by chemical analysis. The minimum requirements for establishing observed contamination in the soil exposure pathway are (1) analytical data that the concentration of at least one hazardous substance attributable to the site is significantly above background level, (2) information that some portion of that increase is attributable to the site, and (3) the hazardous substance is present at the surface or is covered by two feet or less of cover material (e.g., soil) other than an essentially impenetrable material (e.g., asphalt).
	Observed Release	Definition: An observed release is established for the ground water, surface water, or air migration pathway either by chemical analysis or by direct observation. The minimum requirements for establishing an observed release by chemical analysis are analytical data demonstrating the presence of a hazardous substance in the medium significantly above background level, and information that some portion of that increase is attributable to the site. The minimum criterion for establishing an observed release by direct observation is evidence that the hazardous substance was placed into or has been seen entering the medium.
	Office of Solid Waste and Emergency Response	Acronym: OSWER
	Overland Segment	Definition: Portion of the hazardous substance migration path from a source to a surface water body.
	Perennial Water Body	Definition: Contains water throughout the year under normal conditions. Under extreme conditions (e.g., severe drought) some water bodies considered perennial may not contain water.
	Permeability	Definition: The overall ability of water to flow through a geologic material, accounting for all openings in the material (e.g., between grains, through fractures, along lava tubes). For HRS purposes, the terms hydraulic conductivity and permeability are used interchangeably.
	Piles (Other)	Definition: A term reserved for a pile of indeterminate origin that contains hazardous substances.
	Polychlorinated biphenyls	Acronym: PCB
	Population for the Air Migration Pathway	Definition: Number of residents, students, and workers regularly present within the target distance limit. This population does not include transient populations such as hotel and restaurant patrons but may include seasonal populations (e.g., a resort area).
	Population for the Drinking Water Threat	Definition: Number of residents, students, and workers regularly served by surface water intakes that are located within the target distance limit for the surface water bodies evaluated for a given watershed. This population does not includes transients, such as hotel and restaurant patrons, but may include seasonal populations (e.g., a resort area).
	Population for the Ground Water Pathway	Definition: Number of residents, students (and workers regularly served by wells that are located within the target distance limit for the aquifer being evaluated (and appropriate overlying aquifers). This population does not include transient populations, such as hotel and restaurant patrons, but may include seasonal populations (e.g., a resort area).
	Potential Contamination for Listed Sensitive Environments	Definition: For listed sensitive environments, potential contamination is established if no portion of the sensitive environment falls within an area that meets the criteria for an observed release and some portion of the sensitive environment is within the target distance limit of a hazardous substance migration path.
	Preliminary assessment	Acronym: PA
	Probable Point of Entry	Definition: Point at which the overland segment of a hazardous substance migration path intersects with surface water. A site may have multiple PPEs. The PPE is assigned as the point at which entry of the hazardous substances to surface water is most likely. Acronym: PPE
	Production	Definition: Estimate of annual pounds of human food chain organisms harvested for human consumption through all activities, including commercial, recreational, and subsistence fishing. Often times, production can be determined from harvest, catch, or commercial landings data, if the reported data refer only to human food chain organisms.
	Productivity	Definition: Common surrogate for yield data, often expressed as pounds of human food chain organisms present per acre per year. Productivity data are not equivalent to production estimates and cannot be used for HRS purposes.
	Public Recreation Area	Definition: Publicly- or privately-owned area used for recreation by individuals not evaluated as workers in the resident population threat.
	Pumpage Data	Definition: A measure of the volume of water per unit of time discharged from a well, or collected within an intake, either by pumping or free flow. Well pumpage is commonly measured in gallons per minute (gpm), cubic meters per day (m3/day; 1 gpm = 5.45 m3/day), or cubic feet per second (cfs; 1 gpm = 0.0023 cfs). Pumpage data may also be termed well production data, well discharge data, well flow data, well yield data, pumping line data, and for intakes, intake pipe flow data. For HRS purposes, pumpage data relate to the measured or estimated rate of water withdrawal from a well or intake, not from a storage tank or reservoir used as a receptor for water drawn from one or more wells and/or intakes.
	Quality assurance	Acronym: QA
	Quality control	Acronym: QC
	Recognized Expert	Definition: A recognized expert can be a university professor or member of a professional society in a discipline such as ornithology, herpetology, ichthyology, entomology, or botany. The individual also must have published at least one peer-reviewed scientific publication on the area or species of concern.
	Recreational Fishing	Definition: Fishing for pleasure, amusement, relaxation, or nonsubsistence domestic consumption.
	Regular Maintenance	Definition: The routine inspection and testing of a well so that it can be ready for immediate use. This is a criterion for determining whether a standby well may be used to evaluate the population factor. Regular maintenance of a standby well may include direct measurement of the static water level, inspection of the well and pump, and testing of the pump. Such activities generally should be conducted at least once per year, and the operating authority should consider the well functional. Rehabilitation activities, with the intent of retaining a standby well in a state of readiness can also be considered regular maintenance. Such activities include pump cleaning and lubrication, screen and gravel pack cleaning, and treatment for incrustation and/or biofouling.
	Release Sample	Definition: A sample taken to determine whether the concentration of a hazardous substance is significantly above its background level in order to determine whether an observed release (or observed contamination) has occurred.
	Remedial investigation/feasibility study	Acronym: RI/FS
	Resident Individual	Definition: A person who lives or attends school or day care on a property with an area of observed contamination and whose residence, school, or day care center, respectively, is on or within 200 feet of the area of observed contamination. HRSGM Section 9.3 provides guidance for identifying resident individuals.
	Resident Individual Subject to Level I Concentrations	Definition: A resident individual is subject to Level I concentrations if, the concentration of a hazardous substance that meets the criteria for observed contamination is at or above the appropriate benchmark and the sampling location is within the property boundary and within 200 feet of the residence/school. Level I concentrations also may be established if multiple hazardous substances are present below their respective benchmarks, but the I or J index is greater than or equal to one.
	Resident Individual Subject to Level II Concentrations	Definition: A resident individual not subject to Level I concentrations.
	Resident Population	Definition: Total number of people meeting the criteria for resident individual.
	Resource Conservation and Recovery Act	Acronym: RCRA
	Resources	Definition: Resources considered for the soil exposure pathway are commercial agriculture, commercial silviculture, and commercial livestock production or grazing. Resources must be located on an area of observed contamination. See HRSGM Section 9.6 for additional guidance.
	Run-on Control/Runoff Management System, Functioning and Maintained	Definition: A functioning and maintained engineered system or structure designed to prevent flow into or onto a source, or, alternatively, to control runoff from a source and prevent hazardous substance migration.
	Safe Drinking Water Act	Acronym: SDWA
	Salt Water	Definition: Water with an average tidal cycle chloride concentration of 18,700 mg/l or greater (corresponding to a salinity greater than 34 parts per thousand).
	Sample Quantitation Limit	Definition: The quantity of a substance that can be reasonably quantified given the limits of detection for the methods of analysis and sample characteristics that may affect quantitation (e.g., dilution, concentration). Acronym: SQL
	Scrap Metal or Junk Pile	Definition: A pile consisting primarily of scrap metal or discarded durable goods such as appliances, automobiles, auto parts, or batteries, composed of materials that contain or have contained a hazardous substance.
	Secondary Containment	Definition: As used in HRS Table 3-2, secondary containment is applicable to the evaluation of the containment factor for tanks. Methods of secondary containment include a liner external to the tank, a vault, a double-walled tank, or an equivalent device approved by EPA.
	Sensitive Environment in the Air Migration Pathway	Definition: A sensitive environment is defined as a wetland (as defined in 40 CFR 230.3) or any area that meets the criteria listed in HRS Table 4-23. No other areas are considered sensitive environments for the air migration pathway.
	Sensitive Environment in the Surface Water Pathway	Definition: A sensitive environment is defined as a wetland (as defined in 40 CFR 230.3) or any area that meets the criteria listed in HRS Table 4-23. No other areas are considered sensitive environments for the surface water pathway.
	Sessile Organisms	Definition: Organisms permanently attached or established to some substrate for most of their adult live cycle, such as sponges, barnacles, stalked diatoms, and oysters.
	Similar Samples	Definition: Samples from the same environmental medium that are identical or similar in every way except the degree to which they are impacted by a site. For example, two water samples taken from different points in the same stream would be similar samples if they are identical, except that one is contaminated by runoff from a site, while the other is upstream of the site and unaffected by site runoff.
	Single Hydrologic Unit	Definition: The combination of geologic materials and aquifers that are determined to be within the same aquifer boundaries, including all interconnected aquifers.
	Site	Definition: Areas where a hazardous substance has been deposited, stored, disposed, or placed, or has otherwise come to be located. Such areas include multiple sources and may include the area between sources.
	Site inspection	Acronym: SI
	Soil Conservation Service	Acronym: SCS
	Source	Definition: An area where a hazardous substance may have been deposited, stored, disposed, or placed. Also, soil that may have become contaminated as a result of hazardous substance migration. In general, however, the volumes of air, ground water, surface water, and surface water sediments that may have become contaminated through migration are not considered sources.
	Source Aggregation	Definition: The treatment of two or more areas that could be considered individual sources as one discrete source. The area between two or more individual sources may or may not be considered part of the aggregated source.
	Source Hazardous Waste Quantity Factor Value	Definition: The highest of the values assigned to a source using the four hazardous waste quantity tiers.
	Source Type Other	Definition: A source type used when defined source types do not apply. Examples include: contaminated buildings, storm drains, dry wells, injection wells, and French drains. "Other" also can be used for ground water plumes and sediments with no identified source.
	Species Habitat	Definition: The place where a population of a species normally lives and its surroundings, both living and non-living. Habitat generally is characterized by dominant plant form (e.g., broadleaf deciduous forest) and/or physical characteristics (e.g., fast-moving stream with rocky substrate).
	Species Range	Definition: The geographic extent over which a species occurs, including areas that comprise suitable habitat as well as those that do not. Current range refers to the geographic extent over which the species occurs at present; historic range refers to the geographic extent over which the species occurred at some time in the past.
	Specific Capacity	Definition: An alternative term to capacity that is associated with acceptance testing of ground water wells. Specific capacity is reported as the rate at which water is discharged from a well per unit drawdown in the aquifer in which the well is completed. This is usually expressed in gallons per minute per foot (of drawdown) [gpm/ft] or cubic meters per day per meter (of drawdown) [m3/d/m]. The latter term may appear in the technical literature as m2/d.
	Standby Intake	Definition: A surface water intake held in reserve by a water supply entity (e.g., agency, authority, cooperative, private company, or individual) and maintained for use. It is designated as a drinking water supply to be used during a water supply shortage or emergency such as pump failure, drought, sudden water quality deterioration, or interruption in the regular supply.
	Standby Well	Definition: A well held in reserve by a water supply entity (e.g., agency, authority, cooperative, private company, or individual) and is maintained for use. It is designated as a drinking water supply well for use during a water shortage or emergency such as pump failure, drought, sudden water quality deterioration, or interruption in the regular supply. Terms commonly used to signify standby wells include standby wells, reserve wells, drought wells, safety wells, emergency wells, backup wells, substitute wells, and uncommitted wells.
	Standing Crop	Definition: Biomass of all human food chain organisms in a given area of a surface water body at one time. Standing crop data are not equivalent to production estimates and cannot be used for HRS purposes.
	Stocking Rate	Definition: Number of human food chain organisms (or pounds of human food chain organisms) per unit time introduced into a given surface water body by local, state, or Federal fishery agencies.
	Students	Definition: A full- or part-time attendee of an educational institution or day care that is served by a well located within the target distance limit.
	Subsistence Fishing	Definition: Fishing for domestic consumption and nourishment.
	Superfund Accelerated Cleanup Model	Acronym: SACM
	Superfund Amendments and Reauthorization Act	Acronym: SARA
	Superfund Chemical Data Matrix	Acronym: SCDM
	Surface Impoundment	Definition: A topographic depression, excavation, or diked area, primarily formed from earthen materials (lined or unlined) and designed to hold accumulated liquid wastes, wastes containing free liquids, or sludges that were not backfilled or otherwise covered during periods of deposition; depression may be dry if deposited liquid has evaporated, volatilized or leached, or wet with exposed liquid; structures that may be more specifically described as lagoon, pond, aeration pit, settling pond, tailings pond, sludge pit, etc.; also a surface impoundment that has been covered with soil after the final deposition of waste materials (i.e., buried or backfilled).
	Surface Water	Definition: Water present at the earth's surface. Surface water includes rivers, lakes, oceans, ocean-like water bodies, and coastal tidal waters, as defined in HRS section 4.0.2.
	Surface Water Body	Definition: Those surface waters listed in section 4.0.2 and listed on page 8-2.
	Surface Water Samples	Definition: Samples collected from a water body that can be used to establish an observed release to surface water, including aqueous samples, sediment samples, and tissue samples from essentially sessile benthic organisms. (Tissue samples from non-sessile or non-benthic human food chain organisms (e.g., finfish, lobsters, crabs) may be used to establish Level I fishery contamination but not an observed release.)
	Tailings Pile	Definition: A pile consisting primarily of any combination of overburden from a mining operation and tailings from a mineral mining, beneficiation, or processing operation.
	Tank and Ancillary Equipment	Definition: Tanks and associated pipes, pumps, sumps, manifolds, fittings, flanges, and valves used to distribute, meter, or control flow of hazardous substances to or from the tank.
	Target Distance Categories	Definition: Concentric rings (not necessarily circular) with radii 1/4, 1/2, 1, 2, 3, and 4 miles from the sources at the site. These distance categories are used to group the wells subject to potential contamination for distance weighting.
	Target Distance Limit	Acronym: TDL
	Target Distance Limit for the Air Migration Pathway	Definition: Distance over which population and other targets are evaluated. The target distance limit generally is a four-mile radius from the sources at the site. However, if a sampling point meeting the criteria for an observed release is located beyond the four-mile radius, that point defines the outer boundary of the target distance limit. For example, if an observed release is established six miles from the source, the target distance limit is six miles.
	Target Distance Limit for the Ground Water Migration Pathway	Definition: The target distance limit is the distance over which targets are evaluated. For the ground water pathway, the target distance limit is generally a four-mile radius from the sources at the site, except: Any drinking water well with an observed release attributed to the site is evaluated, regardless of its distance from the source.
	Target Distance Limit for the Surface Water Migration Pathway	Definition: Distance over which the in-water segment of the hazardous substance migration path is evaluated. The target distance limit extends 15 miles from the PPE in the direction of flow (or radially in lakes, oceans, or coastal tidal waters) or to the most distant sample point establishing an observed release, whichever is greater. In tidally-influenced surface water bodies, an upstream target distance limit is also determined. For some sites (e.g., sites with multiple PPEs), an overall target distance of greater than 15 miles may result. Acronym: TDL for the Surface Water Migration Pathway
	Target Wells for Aquifer Being Evaluated	Definition: Wells that are located within the target distance limits, and completed in the aquifer being evaluated or an overlying aquifer through which hazardous substances would migrate.
	Terrestrial Sensitive Environment	Definition: A terrestrial sensitive environment is defined as any area that meets the criteria listed in HRS Table 5-5. No other areas are considered terrestrial sensitive environments. Chapter 11 defines each terrestrial sensitive environment and provides sources for identifying terrestrial sensitive environments.
	Terrestrial Vertebrate Species	Definition: Vertebrate species that lay eggs or bear young outside of water. Included are all reptiles, all birds, most mammals, and those amphibians that lay their eggs in shaded, moist sites on land.
	Top of the Aquifer	Definition: In unconfined (water table) aquifers, the uppermost elevation of water, accounting for temporal variations, as long as the water table occurs in the materials used as an aquifer. In confined aquifers, the top of the geologic material producing water.
	Toxic Substances Control Act	Acronym: TSCA
	Trash Pile	Definition: A pile consisting primarily of paper, garbage, or discarded nondurable goods that contain or have contained a hazardous substance.
	Travel Distance	Definition: The shortest overland distance an individual would travel from a residence or school to the nearest area of observed contamination, considering natural barriers (e.g., ravines, streams). If there are no natural barriers, the travel distance is the shortest straight-line distance.
	Treatment, storage, or disposal facility	Acronym: TSDF
	Unallocated Source	Definition: Not an HRS source type, rather a means of including within the hazardous waste quantity factor those hazardous substances or hazardous wastestreams that are known to be at the site but that cannot be allocated to any specific source. Thus, the term only applies for hazardous waste quantity.
	Underground Tank	Definition: A tank with its entire surface area below the surface and not visible; however, a fraction of its associated piping may be above the surface.
	Vertebrate Species	Definition: Animals belonging to the Phylum Chordata, Subphylum Vertebrata. Included are organisms in the Class Agnatha (e.g., lampreys), Class Chrondrichthyes (e.g., sharks, rays), Class Osteichtyhyes (see https://www.google.com/search?rlz=1C1GCEA_enUS1023US1023&sxsrf=ALiCzsYhJ8iewavIZu3URb4RRG_ZBRw8rg:1671740944161&q=Osteichthyes&spell=1&sa=X&ved=2ahUKEwjm-YepiI78AhX3pnIEHROBAPsQkeECKAB6BAgJEAE) (most living forms of fishes), Class Amphibia (e.g., frogs, toads, salamanders), Class Reptilia (e.g., snakes, lizards, turtles, alligators), Class Aves (birds), and Class Mammalia (mammals).
	Vertebrate Species with Semi-Aquatic Habits	Definition: Vertebrate species that either breed in water but live primarily on land (e.g., many amphibians) or breed out of water but live primarily in water (e.g., waterfowl, turtles, alligators, seals). Species in the former category are termed aquatic species with semi-aquatic habits; species in the latter category are termed terrestrial species with semi-aquatic habits.
	Waste characteristics	Acronym: WC
	Water Withdrawal Rotation Program	Definition: Program in which particular surface water intakes within a water supply system are used only for specified intervals, after which other intakes and/or wells are used. Rotation programs are designed to minimize drawdown interference and to maximize efficient use of water in relation to varying water demand. Do not consider an intake that is part of a planned water withdrawal rotation program a standby intake.
	Watershed	Definition: The region drained by, or contributing water to, a surface water body. Watershed evaluations are performed in two areas:(1.) Drainage Area: Portion of the watershed upgradient of sources at the site. (2.) Watershed: Portion of the watershed downgradient of the site. The watershed includes the surface water bodies between the PPEs and the target distance limit (i.e., the in-water segment of the hazardous substance migration path). A single watershed includes all in-water segments that intersect within the target distance limit. A site is in two or more watersheds if two or more hazardous substance migration paths from the sources do not reach a common point within the target distance limit. In these cases, each distinct watershed is evaluated separately.
	Well Log	Definition: A record of geologic materials with depth based on data obtained beneath a point on the land surface and representative of types, depths, and thicknesses of materials beneath that point. The data may represent visual observations, physical/chemical characterizations, and/or geophysical properties. The record also contains information on wells (drinking and monitoring), where appropriate.
	Wellfield Rotation Program	Definition: Program in which part of a wellfield is used for a given interval of time and then another part is used. Generally, a pattern is repeated until every supply well has been used, and then the entire cycle is repeated. Rotation programs are used to minimize drawdown interference and to maximize efficient use of water in relation to varying water demand. Do not consider a well that is part of a planned wellfield rotation program a standby well.
	Wellhead Protection Area	Definition: Areas designated by states according to Section 1428 of the Safe Drinking Water Act, as amended, to protect wells and recharge areas that supply public drinking water systems.
	Wetlands	Definition: Generally include swamps, marshes, bogs, and similar areas. As defined in 40 CFR 230.3 and the HRS, wetlands are those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Such areas can be natural or constructed. Only areas that meet this definition are eligible to be evaluated as wetlands for HRS purposes. Wetlands identified using other definitions (e.g., the Food Security Act of 1985, the wetlands classification system of the U.S. Fish and Wildlife Service, the 1989 Federal Manual for Identifying and Delineating Jurisdictional Wetlands) are not eligible unless they also meet the 40 CFR 230.3 definition (see HRSGD Section 11.1). Additionally, for HRS purposes, isolated wetlands and wetlands contiguous to rivers, lakes, and coastal tidal waters are defined as surface water bodies.
	Worker	Definition: A person working on a property with an area of observed contamination and whose workplace area is on or within 200 feet of an area of observed contamination. Both full and part-time workers are considered.
	Workplace Area	Definition: Any area where workers are regularly present. Areas receiving only brief but regular use (e.g., parking areas, lunch areas) may qualify as work areas if the criteria above are met. The important factor in designating workplace areas is likelihood of exposure rather than duration of exposure.
	Yield	Definition: Maximum amount of human food chain organisms that could be caught by commercial, recreational, and subsistence fishermen from a given water body. Yield is expressed as weight of human food chain organisms present per unit area (or volume) per unit time. Yield data are not equivalent to production estimates and cannot be used for HRS purposes.

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