Environmental Engineering Reference
In-Depth Information
Carbon dioxide:
CO
2
, a common air pollutant and greenhouse gas. Anthropogenically
produced through the combustion of fossil fuels.
Carbon monoxide:
CO, a common pollutant toxic to humans and animal life.
Anthropogenically produced through the combustion of fossil fuels.
Casing:
a hollow tube placed inside a borehole providing access to the subsurface.
Cave:
a natural feature beneath the surface formed by groundwater dissolving away the
rock.
Cavern:
an enlarged void or cavity caused by the dissolution of rock by a fluid.
Cementation:
the precipitation of minerals at grain to grain contacts and within the pore
spaces of sedimentary deposits; after this process is completed a sedimentary
deposit becomes a sedimentary rock.
Channelization:
flood control/navigation efforts for a stream or river involving methods
used to change the channel geometry.
Channel-top sediments:
sediments deposited on top of bar sediments; formed in shal-
low water regions of channels and abandoned channels. Also termed bar-top
sediments.
Chemical:
a substance with a specific atomic composition.
Chemical dehalogenation:
a remedial method performed to remove halogens from
contaminants.
Chemical oxidation:
the loss of electrons.
Chemical reduction:
the addition of electrons.
Chert:
a sedimentary rock composed of silica (SiO
2
); it may form from microscopic organ-
isms secreting silica shells around their bodies or as a secondary precipitant.
Chlorinated solvents:
a group of organic solvents containing one or more chlorine atoms
within their atomic structure.
Chronic response:
a stimulus lingering for a period of time after exposure to a chemical.
Clastic:
consisting of fragments of rock.
Clay:
a clastic sediment with a particle size of less than 1/256 of a mm (4 μm), or fine-
grained minerals of hydrous aluminum-silicate composition.
Combined sewer overflow:
when the wastewater volume in a combined sewer system
exceeds the capacity of the sewer system or treatment plant; the excess wastewater
is discharged directly to nearby streams, rivers, or other water bodies.
Compaction:
the rearrangement of individual grains in a sedimentary deposit; a more
tightly packed sediment forms with the mass staying the same and the volume
decreases.
Completion evaluation study:
a study conducted to confirm the remediation of contami-
nation has been adequate.
Cone of depression:
the three-dimensional shape of water withdrawal from a well.
Confined aquifer:
a permeable geologic unit or strata bounded above and below by rela-
tively impervious geologic material and containing water at a pressure greater
than atmospheric pressure.
Confining unit:
a layer of rock or unconsolidated sediment retarding the movement of
water in and out of an aquifer and possessing a very low hydraulic conductivity.
Congener:
refers to a specific PCB chemical family.
Conjunctive use:
the planned and interchangeable use of groundwater and surface water.
Consistency:
the relative ease an unconsolidated material can be deformed.
Contaminant:
human introduction into the environment of substances harmful to human
health or ecosystems. Also referred to as pollutant.
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