Definition of Contaminant Sources
An area where hazardous substances (including waste and waste constituents) and/or radionuclides are located and/or media where these substances or radionuclides have been deposited, placed, released, or disposed. This is a general term describing a site, a solid waste management unit (SWMU), or an area of contamination or concern (AOC) for which cleanup decisions are applicable. It describes the physical features or boundaries that are potentially contaminated with hazardous substances or radionuclides attributable to current or past operations at the area.
Contaminant sources may be grouped as primary, secondary or tertiary. The differences among these groups are subtle, particularly those differences between secondary and tertiary sources. All of these source groups include contaminated media (e.g., soils, sediment, surface water, groundwater, and air). In addition to contaminated media, the primary source may include containment devices (such as drums, tanks, lagoons) and physical structures, piping, or appurtenances containing the bulk or residuals of hazardous substances, hazardous wastes or hazardous constituents, and radionuclides.
Contamination of secondary and tertiary sources results from releases from the primary source, intermedia transfer, and or transport mechanisms. Contaminated biota could be secondary or tertiary sources for a primary source that has chemicals or radionuclides that are bioaccumulative and amenable to uptake by terrestrial or aquatic species.
Contaminated Ground Water or Plume
An area in the ground water aquifer or saturated zone in subsurface soils containing ground water contaminants that may be dissolved or exist as separate phase products (i.e., Light Non-Aqueous Phase Liquids [LNAPL] or Dense Non-Aqueous Phase Liquids [DNAPL]).
Possible secondary sources:
· Fractured bedrock that has trapped DNAPL
· Conduits (e.g., utility lines or underground piping/sewers) that have trapped LNAPL
· Lake, river, stream, bay, harbor, or coastal waters that receive the ground water plume discharges
· Lake, river, stream, and marine sediment located at the embankment soil/surface water interface that receives the ground water plume discharges
Cooling Towers and Their Discharges -
- Building structures, debris and residuals, and the associated swales and drainage ditches that are currently receiving or have received cooling tower discharges.
Possible secondary sources:
· Surface and subsurface soils within the contaminant source area
· Surface soil immediately downgradient from the source area including soil and sediment in swales, drainage ditches and runoff areas, if any
· Air containing airborne particulates or dust originating from the source area
An aboveground area, including enclosures or berms, sumps, and overflow channels, used to drain liquids off wastewater treatment plant sludges, laboratory tank bottoms, or semisolids. The pad or bed may be constructed of concrete, asphalt, and/or graveled or soil
Possible secondary sources:
· Surface and subsurface soils within the contaminant source area
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust or gaseous materials originating from the source area
An aboveground area that encompasses razed or existing buildings (indoor pistol ranges) and/or open area areas used by security personnel for target practice. Unexploded or spent ammunition containing lead and copper are typical wastes associated with firing ranges.
Possible secondary sources:
· Surface and subsurface soils (for a demolished indoor range) within the contaminant source area (the entire range area)
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
An aboveground area that may contain existing or razed mock-up used to train fire fighting personnel on fire control techniques. A fire training area is typically an outdoor facility that may not be readily identifiable if the area has no engineering structures (e.g., concrete or gravel pads) and has not been used for a long time.
Possible secondary sources:
· Surface and subsurface soils within the contaminant source area
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust originating from the source area
A below ground structure or excavation that may or may not contain engineered piping sections/extensions. It may contain gravel, stones, or other aggregates to allow seepage of liquid waste or the disposal of semi-liquids. This source area may have been filled in with soil and may not be visually identifiable on the ground surface. Historical aerial photos may show these areas barren or devoid of vegetation or ground cover.
Possible secondary sources:
· Surface and subsurface soils within the contaminant source area, including those of the lateral sections or extensions
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust or gaseous materials originating from the source area
· Infiltration seeps at downgradient locations that may or may not be mixed with surface water or shallow groundwater.
Laboratory/Sanitary Sewers and Wastewater Treatment Plants
An area that includes existing or razed structures associated with the treatment of laboratory and/or sanitary wastewaters. Many of these structures may be buried or abandoned in place, broken, and contain sludges that are radioactive or that could be classified as hazardous or mixed wastes.
Possible secondary sources:
· Subsurface soils within the contaminant source area
· Conduits (i.e., including the abandoned in place underground treatment plant components, sewer main, manholes, and lateral sections or extensions) that were part of the sewer systems
· Surface soil (at razed structures or subsurface soil that has been turned over due to demolition and excavation) and surface soil located immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust originating from the source area
An aboveground area or open space on the ground surface where solid waste such as sludges or contaminated soil or sediment are placed, dumped, or discharged, and commingled with soil by mechanical means (e.g., bulldozer or tractor equipped with soil mixing discs. Abandoned landfarms or landfarms that have not been used for a long time may not be visually identifiable.
Possible secondary sources:
· Surface and subsurface soils within the contaminant source area
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust or gaseous materials originating from the source area
A below ground area filled with waste materials, debris, sludges, or contaminated soils. This source is typically abandoned or not operational, uncontrolled, or not designed according to EPA's minimum technology requirements for a land-based disposal unit, and may include the entire physical boundary of the landfill or a portion thereof (e.g., old cells). This source may be covered by soil or an artificial barrier, or may contain exposed contaminated structures, drums, or contaminated surface soil.
Possible secondary sources:
· Subsurface soils that are commingled or in contact with the waste within the landfill
· Surface soil or exposed subsurface soil that is commingled or in contact with the waste within the landfill and surface soil located immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust or gaseous materials vented from the landfill or originating through the landfill cover
· Infiltration seeps at downgradient locations that may or may not be mixed with surface water or shallow groundwater
Lagoon/Pond/Surface Impoundment
A below ground or partially aboveground structure or excavation area containing waste (solid and liquid), a mixture of waste and runoff/precipitation, or their residuals. It may include natural or engineered physical structures such as pipes, swales, and embankments. Equalization ponds for receiving process water and process water/stormwater combined flow are in this category.
Possible secondary sources:
· Subsurface soils that are commingled or in contact with the waste within the lagoon/surface impoundment
· Surface soil or exposed subsurface soil that is commingled or in contact with the waste within the surface impoundment and surface soil located immediately downgradient from the impoundment area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust or gaseous materials originating from the impoundment or its contaminated dikes or embankments
· Infiltration seeps at downgradient locations that may or may not be mixed with surface water or shallow groundwater
Map Tube Vault and Footing Drain
A below ground vault with drainage footing tile systems to divert subsurface water. The vault has multiple compartments (tubes) that can be used to store high level or transuranic wastes that may also contain hazardous substances. Due to maintenance or construction problems, it is not uncommon to find that the vault's structures have been degraded
Possible secondary sources:
· Surface and subsurface soils within the contaminant source area, including the subsurface soil at the footing drain
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust originating from the source area
A below ground concrete structure or tank-like device used to trap or separate oil from process water or fluids containing oil as a free-phase product. It may also contain sludges or residues. Many oil/water separators were abandoned in place, cracked, or had their aboveground structures partially demolished.
Possible secondary sources:
· Surface and subsurface soils within the contaminant source area, including the subsurface soil surrounding the inlet and discharge pipes
· Surface soil immediately downgradient from the source area including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust and gaseous materials originating from the source area
Residual Soils and Sediment After Physical Removal
Surface soil, subsurface soil, or sediments remaining in an area that has undergone physical removal actions (e.g., demolition of a contaminated building). Pursuant to a removal action, physical structures, such as receptacles, tanks, containers, and buildings, and visually contaminated soils, sediments or aggregates may have been removed; however, the residual media may still be contaminated and could be a source for potential exposure pathways.
Possible secondary sources:
· Groundwater in the vadose and saturated zones
· Infiltration seeps at downgradient locations that may or may not have been mixed with surface water or shallow groundwater
Storage Pad for Waste Drums or Containers
A concrete, asphalt, or graveled razed building foundation, or simply a clear open area on the ground. Typically, debris, abandoned equipment or articles, and waste containers of different sizes and shapes are stored on these pads.
Possible secondary sources:
· Surface and subsurface soils (if the pad has poor integrity) within the contaminant source area
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
An above groundarea or a depression on the ground surface where scrap metal, solid waste, drums (with or without their contents), and other contaminated aggregates or media are placed, discharged, or abandoned. The waste pile may or may not have an engineered barrier such as concrete or asphalt pads between the waste materials and the soil. Typically, the waste pile is not covered by a roof, although sometimes canvas or plastic tarp may be used to cover the waste materials either partially or entirely.
Possible secondary sources:
· Surface and subsurface soils (if the pile has no engineering barrier or if the barrier has poor integrity) within the contaminant source area
· Surface soil immediately downgradient from the source area, including soil and sediment in swales, drainage ditches, and runoff areas, if any
· Air containing airborne particulates/dust and gaseous materials originating from the source area