Environmental Engineering Reference
In-Depth Information
Influent stream:
when a stream loses water to groundwater. Also referred to as losing
stream.
In situ soil flushing:
a groundwater remedial method that pumps or percolates water
or chemicals into the ground. The objective is to flush or drive the contaminants
present in the saturated soil to a location where they can be removed, typically by
a pumping well.
In situ thermal treatment:
a remedial method for soil that injects a form of heat into the
affected area in an effort to mobilize the contaminants so they can be more easily
removed.
Isomer:
chemicals with the same molecular formula but a different molecular structure.
Isopotential level:
an imaginary surface representing the static level groundwater would
rise to. Also referred to as potentiometric surface, pressure level, and piezometric
surface.
Isotropic:
low variability of a specific geologic feature when measured in different
directions.
Kame:
a glacial sedimentary deposit formed as an ice contact feature by glacial meltwater;
consists of a conical-shaped mass of course-grained sand and gravel with little or
no fine-grained material.
Karst topography:
a landscape created by groundwater slowly dissolving sedimentary
rock such as limestone.
Kettle:
a glacial sedimentary feature consisting of a depression formed when portions of
ice from a glacial front become partially or wholly buried with glacial outwash.
Lacustrine deposits:
sedimentary strata deposited in lakes.
Laminae:
very thinly bedded sedimentary layers.
Land use restrictions:
a remedial method of placing restrictions on land use to protect
human health and environment so any contamination left in place is not disturbed.
Latency period:
the duration of time without an observable effect following exposure to
a chemical.
Lateral moraine:
a moraine formed on the sides of glaciers.
LD
50
:
dose of a substance that is lethal to 50% of the test subjects.
Light nonaqueous phase liquids:
organic compounds that do not readily mix or dissolve
in water and are lighter that water.
Limestone:
a sedimentary rock composed of calcium carbonate (CaCO
3
) and formed pre-
dominantly in marine environments from the accumulation of shells, shell frag-
ments, or from the direct precipitation from water (usually seawater).
Lithification:
a complex process where unconsolidated geologic materials become rock
mainly through compaction and cementation.
Lodgment till:
a moraine deposit formed under the ice between lateral moraines. Lodgment
till deposits may also be termed ground moraines.
Longshore current:
movement of water along a shoreline caused by waves crashing along
a beach at an angle.
Losing stream:
when a stream loses water to groundwater. Also referred to as influent
stream.
Lowest-observed-adverse-effect level:
the lowest tested dose of a chemical or substance
causing a harmful or adverse health effect. Also referred to as threshold effect
value.
Mass wasting:
the movement of rock or soil downslope by gravity without the aid of mov-
ing water, glaciers, or wind.
Search WWH ::
Custom Search