| pentachlorophenol (PCP) | A chemical compound containing carbon, chlorine, oxygen, and hydrogen, is a contaminant used in feed stock material and chemical manufacturing. |
| perched aquifer | An unconfined aquifer contained by impermeable rock. See definition of aquitard. |
| permeability |
The relative ease with which rock, soil, or sediment will transmit
a fluid (liquid or gas). High permeability indicates that medium does not significantly
retard the flow.
|
| pesticide | A substance or mixture of substances intended to prevent or mitigate infestation by, or destroy or repel, any pest. |
| pH |
"Potential of hydrogen." This is a measure of the
acidity or alkalinity of a solution. The pH scale ranges from 0 (extremely acidic)
to 14 (extremely alkaline). Distilled water and neutral solutions have a pH equal
to 7.
|
| phase (physical/chemical) | A physically distinct and separable form of matter that may be a single compound. For example, water is stable in three phases: solid (ice), liquid, and vapor. Treatment systems often use phase differences to separate contaminants from water. |
| phenols |
One of a group
of organic compounds that are byproducts of petroleum refining, tanning, and textile,
dye, and resin manufacturing. |
| phytoremediation
|
The term phyto- means plant. Phytoremediation
is a general term for several ways in which plants are used to clean up sites
by removing pollutants from soil and water. |
| phytoremediation |
A remediation technology that uses
plants and trees for contaminated soil and groundwater. See technology description
of Phytoremediation. |
| plume |
A well defined, usually mobile, area
of contamination in groundwater, soil or the air. . |
| point source |
A stationary location or fixed facility
from which pollutants are discharged or emitted or any single, identifiable discharge
point of pollution, such as a pipe, ditch, or smokestack. |
| polychlorinated
biphenyls (PCBs) |
Any number of biphenyls in which hydrogen
atoms on the benzene ring is substituted with chlorine. As a group, they are persistent
chemicals in the environment. PCBs were used in high voltage electrical transformers
and capacitors because they conducted heat well while being fire resistant and
good electrical insulator. Further sale or use of PCBs was banned in |
| polynuclear
aromatic hydrocarbon (PAH) |
A chemical compound that contains
more than one benzene ring. They are commonly found in petroleum fuels, coal products,
and tar. |
| porosity |
A measure of the total void space
in a media. Porosity is not equivalent to permeability, as certain rocks maybe
very porous but relatively impermeable. |
| ppb |
Part per billion. |
| ppm |
Parts per million. |
| presumptive
remedies |
Preferred technologies identified
through historical patterns of remedy selection and EPA's scientific and engineering
evaluation of performance data on technology implementation. |
| pug mill |
A hand-driven machine which further
crushes and blends powder clay. |
| pump-and-treat |
A groundwater treatment process that
pumps water to the surface and treats it to remove or destroy the contaminant.
See technology description of Pump and Treat.
|
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