Environmental Engineering Reference
In-Depth Information
Principle of cross-cutting relationships:
when a layer of sediment is cut by faulting, or
the intrusion of an igneous dike or sill; the sedimentary layer is older than the
event or feature cutting the layer.
Principle of faunal and floral succession:
explains the relationship between biological
evolution and sedimentary deposits.
Principle of original horizontality:
sediments formed from sedimentary processes are
generally deposited as horizontal sheets.
Principle of superposition:
defines the depositional sequence of undeformed strata of
rock or sediment—what is youngest is on top.
Principle of uniformity:
the external and internal processes on and within Earth observed
today have been operating unchanged and, at the same approximate rates, for a
very long period of time throughout most of Earth's history.
Property:
a parcel of land with a specific and unique legal description.
Pump and treat:
a groundwater remedial method involving the extraction of groundwater
by pumping it from the ground and treating the contaminated groundwater at the
surface.
Radioactive decay:
a spontaneous loss of energy through the emission of ionizing par-
ticles and radiation by an unstable atomic nucleus.
Rain drop prints:
small circular impressions formed from raindrops hitting the soft sur-
face of an exposed sediment; subsequent burial preserves the feature.
Receptor:
the organism or ecological habitat where exposure to a substance or agent may
occur.
Recognized environmental condition:
the presence or likely presence of any hazardous
substance or petroleum product on a property or site under conditions that may
materially affect or threaten the environmental condition of the property or site,
human health or the environment.
Reductant:
an atom receiving an electron.
Reduction:
the loss of areal coverage of an ecosystem or community.
Regolith:
weathered rock devoid of organic material.
Regressive sedimentary sequence:
sediment with vertically increasing coarser grains;
commonly indicates decreasing water depths and increasing energy.
Remediation:
meaning “remedy”—the process of cleaning up or reducing the risks posed
by the presence of contamination.
Remedial action:
a step or steps undertaken to remedy or lower the risks posed to human
health or the environment by the presence of contamination at a property or site.
Remedial action plan:
a description of the steps to be undertaken to remedy or lower the
risks posed by the presence of contamination at a property or site to human health
or the environment.
Remedial investigation:
a comprehensive qualitative and quantitative environmental
investigation conducted at large and complex contaminated properties or sites.
Retardation:
the slowing of the migration of contaminants.
Ripple marks:
small dune-like deposits whose long axes are perpendicular to the air or
water current where they formed.
Risk assessment:
a procedure used to evaluate whether there is an unacceptable risk
posed to humans or the environment from natural events, human activity, or spe-
cific substances.
Rock:
a solid object composed of minerals.
Rockfall or debris fall:
the rapid descent of a rock mass vertically from a cliff, or by leaps
down a very steep slope.
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