Contaminated and Hazardous
Waste Site Management Glossary
P
P-Wave:
An elastic body wave in which particles move in the direction of propagation.
It is the wave assumed in most seismic surveys. Also called primary or push-pull
wave. Packer:
A device placed in a well or borehole to isolate or seal a section at a certain
level. Paraffins:
See Alkanes. Partial
Pressure: The portion of total vapor pressure in a system due to one or more constituents
in the vapor mixture. Particle
Mass Density: The oven-dried mass of the sample divided by the volume of the solid
particles. Partitioning:
Chemical equilibrium condition where a chemical's concentration is apportioned
between two different phases according to the partition coefficient, which is
the ratio of a chemical's concentration in one phase to its concentration in the
other phase. Pathogen:
A disease-producing agent; usually a living organism. Peat:
An unconsolidated deposit of partially decomposed plant matter with high moisture
content, in a water-saturated environment. Percentage
Frequency Effect (PFE): The percent difference in resistivity measured at two
frequencies (one high, one low). It is the basic polarization parameter measured
in frequency domain resistivity surveys. Equivalent to chargeability in time domain
surveys. Percent
Difference (%D): The percent difference indicates both the direction and the magnitude
of the comparison (i.e., the percent difference may be either negative, positive,
or zero). In contrast, see relative percent difference below. Percent
Moisture: An approximation of the amount of water in a soil/sediment sample made
by drying an aliquot of the sample at 105C. The percent moisture determined in
this manner also includes contributions from all compounds that may volatilize
at or below 105C, including water. Percent moisture may be determined from decanted
samples and from samples that are not decanted. Percent
Solids: The proportion of solid in a soil sample determined by drying an aliquot
of the sample. Perched:
Normally refers to a perched water table, which is a water table for a zone saturated
with water, but underlain by an unsaturated zone and another water table. Often
caused by a low-permeability layer which caused infiltrating water to "pond"
or perch above it. Perched
Aquifer: A special case of unconfined aquifer which occurs wherever an impervious
(or semipervious) layer of limited areal extent is located between the regional
water table of an unconfined aquifer and the ground surface. Perched
Groundwater: Groundwater separated from another underlying body of groundwater
by a confining layer, often clay or rock. Perched
Water Table: A separate continuous body of groundwater lying (perched) above the
main water table. Clay beds located within a sedimentary sequence, if of limited
aerial extend, may have a shallow perched groundwater body overlying them. Percolation:
The downward flow or filtering of water or other liquids through subsurface rock
or soil layers, usually continuing downward to groundwater. Percussion
Drilling: A method in which a hammering action by a bit breaks rock into small
particles which can be removed from the borehole, thus advancing the borehole. Performance
Evaluation (PE) Sample: A sample of known composition provided by regulatory agency
for laboratory analysis. Peristaltic
Pump: A low-volume pump in which suction is induced through the compression of
a flexible tube by a rotor. Permafrost:
Perennially frozen ground in areas where the temperature remains at or below 0o
C for two or more years in a row. Permanent
Magnetism: See Remanent Magnetism. Permeability:
A qualitative description of the relative ease with which rock, soil, or sediment
will transmit a fluid (liquid or gas). Often used as a synonym for hydraulic conductivity
or coefficient of permeability. Permeable
Reaction Wall: Is similar to a cutoff wall, but the wall is relative to aquifer
permeable so that groundwater flows through it unimpeded. The wall has reactive
materials within it to cause destruction or absorption (or both) of the contaminants.
A permeable reaction wall can be a passive alternative to pump-and-treat for plume
control. Permeameter:
A laboratory device which measures the intrinsic permeability and hydraulic conductivity
of a solid or rock sample. Permittivity:
The property which enables a three-dimensional material to store electrical charge;
i.e. its capacitivity. Petrochemicals:
Chemical substances produced from petroleum in refinery operations and as fuel
oil residues. These include fluoranthene, chrysene, mineral spirits, and refined
oils. Petrochemicals are the bases from which volatile organic compounds (VOCs),
plastics and many pesticides are made. These chemical substances are often toxic
to humans and the environment. pH:
A measure of the acidity of a solution. pH is equal to the negative logarithm
of the concentration of hydrogen ions in a solution. A pH of 7 is neutral. Values
less than 7 are acidic, and values greater than 7 are basic. Phase:
A homogeneous, physically-distinct portion of the subsurface. For example, groundwater,
soil gas. For geophysical use, see In-phase and Phase Shift. Phase
Shift: A measure of the offset between two periodic signals of the same frequency.
Measured in degrees or radians/milliradians. Phototrophs:
Organisms that use light to generate energy (by photosynthesis) for cell synthesis. Phreatophytes:
Plants with deep root systems which allow them to get water from the groundwater
or the capillary fringe. Physical
Chemical Separation: The treatment process of adding a chemical to a substance
to separate the compounds for further treatment or disposal. Piezometer:
A nonpumping well, generally of small diameter, which is used to measure the elevation
of the water table or potentiometric surface. A piezometer generally has a short
well screen and the water level within the casing is considered to be representative
of the potentiometric surface at that particular depth in the aquifer. Piezometer
Nest: A set of two or more piezometers set in close proximity to one another but
screened at different depths. This allows for determination of vertical flow gradients
or differences in water chemistry with depth. Piezometric
Level: See Potentiometric Surface. Piezometric
Surface: An outdated term for "potentiometric surface". Pilot
Test: Operation of a small-scale version of a larger system to gain information
relating to the anticipated performance of the larger system. Pilot test results
are typically used to design and optimize the larger system. Piston
Pump: A pump that has a piston rod, cylinder and check valve mechanism which forces
water to the surface through positive displacement. Pitot
Tube: A device used to measure the total pressure of a fluid stream that is essentially
a tube attached to a manometer at one end and pointed upstream at the other. Plasticity:
The property of a solid body when it experiences a permanent change in shape or
size due to a stress exceeding a certain value. Plasticity
Index (PI): The range of water content where the soil is in a plastic state. PI
is calculated as the difference between the percent liquid limit and percent plastic
limit. Plastic
Limit (PL): The lower limit of the plastic state of a soil (see Atterberg Limits). Plastic
Soil: One that will deform without shearing (typically silts or clays). Plasticity
characteristics are measured using a set of parameters known as Atterberg Limits. Plume:
A body of contaminated groundwater or vapour originating from a specific source
and influenced by certain factors such as local groundwater or soil vapour flow
patterns and character of the aquifer. The zone of contamination that exhibits
dissolved-phase contaminants at concentrations above some specified concentration
level, such as a drinking water limit, detection limit or background. The volume
of the subsurface that encompasses the plume also must encompass the residual
lenses or pools of NAPL that feed dissolved-phase mass to the plume. To restore
permanently groundwater at a site, both the plume and the immiscible-phase liquid
(residual, lenses and pools) must be removed. To avoid confusion, the term "plume"
should not be used to refer to a pool of free phase immiscible liquid. Plume removal
refers to the removal of the dissolved-phase mass that constitutes the plume.
NAPL removal refers to removal of the immiscible-phase liquid. Poisson
Ratio: The ratio of the transverse contracting strain to the elongation strain
when a rod is stretched by forces applied at its ends, parallel to the its axis. Polarize,
Polarization, Polarizable: Separation of charge, as in induced polarization or
IP. Polishing:
Refers to the application of remedial technologies to NAPL zones which have been
reduction remediated previously (i.e., removal of immiscible-phased liquid) by
other technologies. polishing is a cleanup phase that would normally be applied
in order to remove or destroy dissolved-phase liquids in residual, lenses, or
pools. To achieve 'groundwater restoration', an aquifer
would generally need to be polished after other remedial measures have been taken
to remove nearly all of the mass of immiscible-phase (NAPL) liquid. Pollution:
Generally, the presence of matter or energy whose nature, location or quantity
produces undesired health or environmental effects. Polychlorinated
Biphenyls (PCBs): A group of toxic chemicals used for a variety of purposes including
electrical applications, carbonless copy paper, adhesives, hydraulic fluids, microscope
immersion oils and caulking compounds. PCBs are also produced in certain combustion
processes. PCBs are extremely persistent in the environment because they are very
stable, non-reactive and highly heat resistant. Chronic exposure to PCBs is believed
to cause liver damage. It also is known to bioaccumulate in fatty tissues. PCB
use and sale was banned in 1979 with the passage of the Toxic Substances Control
Act. Polycyclic
Aromatic Hydrocarbons or Polyaromatic Hydrocarbons (PAHs): PAHs, such as pyrene,
are a group of highly reactive organic compounds found in motor oil. They are
a common component of creosotes and can cause cancer. Polynuclear
Aromatic Hydrocarbons (PNAs): PNAs, such as naphthalene and biphenyls, are a group
of highly reactive organic compounds that are a common component of creosotes,
which can be carcinogenic. Pool:
A zone of free-phase immiscible liquid that resides at the bottom of an aquifer.
A pool rests on top of an aquitard. A pool may be in an immobile state or it may
be in a state of motion, depending on whether or not free-phase liquid is being
added to the pool. Pore
Pressure: The stress produced by fluid which fills the voids between soil or rock
particles. Pore
Space: An opening, void or interstice in a soil or rock mass. Pore
Volume: The volume of water (or air) that will completely fill all of the void
space in a given volume of porous matrix. Pore volume is equivalent to the total
porosity. The rate of decrease in the concentration of contaminants in a given
volume of contaminated porous media is directly proportional to the number of
pore volumes that can be exchanged (circulated) through the same given volume
of porous media. Porosity:
The ratio of the volume of pore spaces in a rock or sediment to the total volume
of the rock or sediment. Porosity,
Primary: The pore spaces which were created at the time of deposition of a soil
or rock unit. Porosity,
Secondary: The pore spaces which were created after the time of deposition of
a soil or rock unit (e.g. fractures, solution channels). Potential
Energy: Energy derived from position rather than motion, with respect to a specified
datum in a field of force. Potential
Well Yield: An estimate of well yield generally above the existing yield rate
or test rate, but considered possible on the basis of available information, data
and present well performance. Potentiometric
Map: A map which shows through contour lines or other symbols, the potentiometric
surface elevation of an aquifer. Potentiometric
Surface: A surface that represents the level to which water in a confined aquifer
would rise in a well tapping the aquifer. If the head varies significantly with
depth in the aquifer, then there may be more than one potentiometric surface,
depending upon the depth at which the potentiometric surface is measured. The
water table can be considered to be the potentiometric surface for an unconfined
aquifer. ppm:
Parts per million (10,000 ppm = 1%). Precipitation:
a) Formation of solids out of dissolved constituents; it is caused by a change
in conditions (e.g. temperature) b) Water that falls to the ground surface from
the atmosphere as rain, snow, hail, sleet, etc.. Precision:
The reproducibility of a measurement; the closeness of each of a set of similar
measurements to the arithmetic mean of that set. Preliminary
Assessment: The process of collecting and reviewing available information about
a known or suspected waste site or release to determine if a threat or potential
threat exists. Preparation
Blank (reagent blank, method blank): An analytical control that contains distilled/deionized
water and reagents, which is carried through the entire analytical procedure (digested
and analyzed). An aqueous method blank is treated with the same reagents as a
sample with a water matrix; a solid method blank is treated with the same reagents
as a soil sample. Preservative:
A chemical added to organic (or inorganic) water samples to maintain the integrity
of the sample. Some common preservatives include nitric acid, hydrochloric acid,
phosphoric acid, sodium hydroxide, and refrigeration. Some samples are also contained
in amber bottles to prevent deterioration of the sample by light. Pressure
Gradient: A pressure differential in a given medium (e.g., water or air) which
tends to induce movement from areas of higher pressure to areas of lower pressure. Pressure
Head: The height of a column of static fluid which is necessary to develop a specific
pressure. Primary
(magnetic field): The magnetic field generated by an EM transmitter. May induce
a secondary magnetic field. Primary
Porosity: See Porosity, Primary. Procaryotes:
A cellular organism in which the nucleus has no limiting membrane. Processing:
Geophysically, to change data so as to emphasize certain aspects or correct for
known influences, thereby facilitating interpretation. Profiling:
In geophysics, a survey method whereby an array of sensors is moved along the
Earth's surface without change in its configuration, in order to detect lateral
changes in the properties of the subsurface (faults, buried channels, etc..).
The alternative is usually a sounding. Protocol:
Describes the exact procedures to be followed with respect to sample receipt and
handling, analytical methods, data reporting and deliverables, and document control.
Used synonymously with Statement of Work (SOW). Protozoa:
Single-celled, eucaryotic microorganisms without cell walls. Most protozoa are
free-living although many are parasitic. The majority of protozoa are aerobic
or faculatively anaerobic heterotrophs. Pseudosection:
A cross section showing the distribution of a geophysical property, such as seismic
travel time, from which the distribution of the geological property of interest
(depth to bedrock, for example) can be interpreted. Psi
(pounds per square inch): A unit of pressure or pressure drop across a flow resistance.
One psi is equivalent to the pressure exerted by 2.31 feet of water column (0.0684
atmospheres). Psig
(pounds per square inch (gauge): 0 psig = 14.696 psia (psi (absolute)) = 1.0 atmosphere. Pugmill:
A chamber in which water and soil are mixed together. Typically mixing is aided
by an internal mechanical stirring/kneading device. Pumping
Interference: The condition occurring when a pumping well lowers the water level
in a neighbouring well. Pumping
Test: An aquifer test in which a well is pumped for a certain period of time and
the change in hydraulic head in observation wells is recorded. It is used to determine
the capacity of a well and hydraulic characteristics of the aquifer. Pump-and-Treat:
This term is reserved for the removal of water containing dissolved-phase contaminants
by means of wells or trenches. The water is treated on surface. Pump-and-treat
can be used either for plume migration control or hydraulic containment in the
zone where immiscible-phase liquid occurs or both. Purge,
Purging: Process of removing stagnant water from a well before sampling. Purge-and-Trap
(P&T): Analytical technique (device) used to isolate volatile (purgeable)
organics by stripping the compounds from water or soil by a stream of inert gas,
trapping the compounds on an adsorbent such as a porous polymer trap, and thermally
desorbing the trapped compounds into the gas chromatographic column.
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