Contaminated and Hazardous
Waste Site Management
half-life is the time required for half of a given quantity of material to decay.
Chemically, it is the time required for half of a given quantity of material to
undergo a chemical reaction.
When hard water is used with soap it will form an insoluble residue and hard water
will form a scale in utensils in which the water has been allowed to evaporate.
Hardness is mainly caused by calcium and magnesium ions. Hardness is generally
expressed in mg/L calcium carbonate (Ca CO3).
Waste: By-products of society that can pose a substantial present or potential
hazard to human health and the environment when improperly managed. It possesses
at least one of four characteristics (ignitabiliy, corrosivity, reactivity, or
toxicity), or appears on special EPA lists.
The empty volume in a container between the cap and the water level of the sample.
The source and upper part of a large stream or river, including the drainage basin.
Capacity: The quantity of energy that must be supplied to raise the temperature
of a substance. For contaminated soils heat capacity is the quantity of energy
that must be added to the soil to volatilize organic components. The typical range
of heat capacity of soils is relatively narrow, therefore variations are not likely
to have a major impact on application of a thermal desorption process.
Metals: Metallic elements, some of which are required in trace concentrations
for plant and/or animal nutrition, but which become toxic at higher concentrations
(e.g. lead, mercury).
Oils: Petroleum products dominantly composed of large molecular weight, structurally-complex
Law: An empirical law which states that the quantity of gas/vapour dissolved in
water is proportional to the pressure of the gas/vapour in contact with the water
at a specified temperature, i.e. as gas pressure increases, gas concentration
in the water increases.
Law Constant: The ratio of the concentration of a compound in air (or vapor) to
the concentration of the compound in water under equilibrium conditions. Henry's
Law Constants are temperature dependent.
The part of the subsurface that is different in some property (hydraulic conductivity,
Composed of non-uniform constituents whose material properties vary in space.
All geological material is heterogeneous, but the property of interest (porosity,
for example) may be sufficiently uniform for the material to be treated as homogeneous
in terms of that property.
Designating or typical of organisms that derive carbon for the manufacture of
cell mass from organic matter.
Time: The elapsed time expressed in days from the date of receipt of the sample
by the contractor until the date of its analysis. Holding time = (sample analysis
date - sample receipt date)
Characteristic of a medium in which material properties are identical throughout.
Although heterogeneity, or non-uniformity, is the characteristic of most aquifers,
assumed homogeneity, with some other additional assumptions, allows use of analytical
models as a valuable tool for approximate analyses of groundwater movement.
Composed of uniform constituents throughout. That is, having material properties
(e.g., hydraulic conductivity) which do not vary in space.
Conductivity: A measure of the ability of a fluid to flow through a porous medium
determined by the size and shape of the pore spaces in the medium and their degree
of interconnection and also by the viscosity of the fluid. Hydraulic conductivity
can be expressed as the volume of fluid that will move in unit time under a unit
hydraulic gradient through a unit area measured at right angles to the direction
Gradient: The slope of the groundwater level or water table.
Head: Height above a datum plane (such as mean sea level) of the column of water
that can be supported by the hydraulic pressure at a given point in a groundwater
system. Equal to the distance between the water level in a well and the datum
Chemical compounds composed only of carbon and hydrogen.
Peroxide: H2O2. Hydrogen peroxide is used to increase the dissolved oxygen content
of groundwater to stimulate aerobic biodegradation of organic contaminants. Hydrogen
peroxide is infinitely soluble in water, but rapidly dissociates to form a molecule
of water (H2O) and one-half molecule of oxygen (O). Dissolved oxygen concentrations
of greater than 1,000 mg/L are possible using hydrogen peroxide, but high levels
of D.O. can be toxic to microorganisms.
Model: A representation, often simplified and perhaps conceptual, of the hydrogeological
flow system. The aspects important for the site are emphasized. See also model.
The geology of groundwater, with particular emphasis on the chemistry and movement
A graphical plot of changes in elevation of water or flow of water with respect
Cycle: The continued circulation of water between the ocean, atmosphere and land
is called the hydrologic cycle.
Having an affinity for water ("water-loving"), or capable of dissolving
in water; soluble or miscible in water.
Tending not to combine with water, or incapable of dissolving in water; insoluble
or immiscible in water ("water-fearing"). A property exhibited by non-polar
organic compounds, including the petroleum hydrocarbons.
A condition of low oxygen concentration, below that considered aerobic.
Unit: A formation, part of a formation, or a group of formations which have similar
Phenomenon in which properties such as capillary pressure or relative permeability
may differ depending on whether a fluid-fluid interface is advancing (imbibition)
or receding (drainage).