Glossary

Glossary

PARTICLE SIZE:

The diameter, in millimeters, of suspended sediment or bed material. Particle-size classifications are:

              [1] Clay—0.00024-0.004 millimeters (mm);

              [2] Silt—0.004-0.062 mm;

              [3] Sand—0.062-2.0 mm; and

              [4] Gravel—2.0-64.0 mm. 

PARTS PER BILLION (PPB):

A unit of measure used to describe levels or concentrations of contamination. A measure of concentration equaling 0.0000001 percent. For example, One part per billion is the equivalent of one drop of impurity in 500 barrels of water. Most drinking water standards are ppb concentrations.

PARTS PER MILLION (PPM):

A unit measure used to describe levels or concentrations of contamination. A measure of concentration equaling 0.0001 percent. One part per million would be equivalent to one drop of water in twenty gallons. When looking at contamination of water and soil, the toxins are often measured in ppm concentrations. 

PENTACHLOROPHENOL (PCP):

A petroleum-based chemical that is used as a wood preservative because it kills fungus and termites.

PERCHED GROUNDWATER:

Water that accumulates beneath the earth's surface but above the main water-bearing zone (aquifer). Typically, perched groundwater occurs when a limited zone (or lens) of harder, less permeable soil is "perched" in otherwise porous soils. 

PERCHLOROETHYLENE (PCE):

A volatile organic compound used primarily as a dry-cleaning agent. It is often referred to as "perc" and is a major source of groundwater contamination. 

PERMEABILITY:

The ability of a material to allow the passage of a liquid, such as water through rocks. Permeable materials, such as gravel and sand, allow water to move quickly through them, whereas impermeable materials, such as clay, don’t allow water to flow freely.

PERMEABLE LAYER:

 A layer of porous material (rock, soil, unconsolidated sediment). In an aquifer, the layer through which water freely passes as it moves through the ground. 

PESTICIDE:

A substance or mixture of substances intended to prevent or mitigate infestation by, or destroy or repel, any pest. Pesticides can accumulate in the food chain and or contaminate the environment if misused.

PETROLEUM:

Crude oil, or any fraction thereof, which is liquid at standard conditions of temperature of pressure, which means at 60 degrees Fahrenheit and 14.7 pounds per square inch absolute pressure.

pH:

A convenient way of describing the strength of an acidic or basic aqueous solution. The values range from 0 to 14, with a pH of 7 corresponding to neutral. As the pH number becomes smaller by one unit, the acidity increases by a factor of 10 (for 2 units, it changes by 100, and so on). Likewise, as the pH number increases by one unit, the alkalinity (basic property) increases by a factor of 10, etc.; tap water may lie in a region from above 6 to below 8. Strongly acidic waste solutions (pH less than 2) and strongly basic ones (pH greater than 12.5) are defined as hazardous wastes because of their corrosiveness. 

PHASE I:

First-stage environmental audit. Essentially a historic records search to find out ownership history and what kinds of chemical processes might have been carried out at a site. Phase I also includes a visit to the site, but no testing. If Phase I shows no significant concerns, no Phase II or III is necessary.

PHASE II:

Second-stage environmental audit. Includes site tests to confirm the location of hazards and identify them. The report also makes recommendations for cleanup.

PHASE III:

(See REMEDIATION.)

PHENOLS:

One of a group of organic compounds that are byproducts of petroleum refining, tanning, and textile, dye, and resin manufacturing.

PHOTO-IONIZATION DETECTOR (PID):

Instrument to detect either gross total contamination or through use of capillary chromatography column to identify and quantify concentrations of selected volatile compounds.

PHYTOREMEDIATION:

The use of plants and trees to remove or neutralize soil or water contaminants, including metals, pesticides, solvents, explosives, crude oil, polyaromatic carbons, and landfill leachates.  Use is generally limited to sites at which concentrations of contaminants are relatively low and contamination is found in shallow soils, streams, and groundwater.

PIEZOMETERS:

Small-diameter wells used to measure groundwater levels.

PILOT TESTS:

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.

PLUME:

A body of contaminated groundwater flowing from a specific source. The movement of the plume is influenced by such factors as local groundwater flow patterns, the character of the aquifer in which the groundwater is contained, and the density of contaminants.

POINT SOURCE:

A discernible, confined and discrete conveyance such as a pipe, ditch or channel, tunnel, conduit, well container, concentrated animal feeding operation or vessel, from which pollutants are or may be discharged. Does not include agricultural stormwater discharges and return flows from irrigated agriculture.

POINT SOURCE:

A discernible, confined and discrete conveyance such as a pipe, ditch or channel, tunnel, conduit, well container, concentrated animal feeding operation or vessel, from which pollutants are or may be discharged. Does not include agricultural stormwater discharges and return flows from irrigated agriculture.

POLYCHLORINATED BIPHENYLS (PCBs):

A group of synthetic, toxic industrial chemical compounds once used in making paint and electrical transformers, which are chemically inert and not biodegradable. PCBs were frequently found in industrial wastes, and subsequently found their way into surface and ground waters. As a result of their persistence, they tend to accumulate in the environment. In terms of streams and rivers, PCBs are drawn to sediment, to which they attach and can remain virtually indefinitely. Although virtually banned in 1979 with the passage of the Toxic Substances Control Act, they continue to appear in the flesh of fish and other animals.

POLYNUCLEAR AROMATIC HYDROCARBONS (PAHs or PNAs):

PNAs or Polynuclear Aromatic Hydrocarbons, are natural constituents of crude oil, and also may be formed when organic materials such as coal, oil, fuel, wood or even foods are not completely burned. PNAs are also found in lampblack, a by-product of the historic gas manufacturing process. PNAs are found in a wide variety of other materials, including diesel exhaust, roofing tars, asphalt, fireplace smoke and soot, cigarettes, petroleum products, some foods, and even some shampoos. PNAs tend to stick to soil and do not easily dissolve in water, and generally do not move in the environment.

POROSITY:

A measure of the water-bearing capacity of subsurface rock. With respect to water movement, it is not just the total magnitude of porosity that is important, but the size of the voids and the extent to which they are interconnected, as the pores in a formation may be open, or interconnected, or closed and isolated. For example, clay may have a very high porosity with respect to potential water content, but it constitutes a poor medium as an aquifer because the pores are usually so small.

PORTER-COLOGNE WATER QUALITY CONTROL ACT:

Enacted by California Legislature in 1970, it contains a complete framework for the regulation of waste discharges to both surface and ground waters of the State. It further provides for the adoption of water quality control plans and the implementation of these plans by adopting waste discharge requirements for each discharger of waste that could impact the waters of the state.

POTABLE WATER:

Water of a quality suitable for drinking.

POTENTIALLY RESPONSIBLE PARTY (PRP):

An individual, company or government body identified as potentially liable for a release of hazardous substances to the environment. By federal law, such parties may include generators, transporters, storers and disposers of hazardous waste, as well as present and past site owners and operators.

POTENTIOMETRIC SURFACE:

A surface that represents the level to which water will rise in tightly cased wells.  If the head varies significantly with depth in the aquifer, then there may be more than one potentiometric surface.  The water table is a particular potentiometric surface for an unconfined aquifer.

PRELIMINARY ENDANGERMENT ASSESSMENT (PEA):

 Provides basic information for determining if there has been a release of a hazardous substance that presents a risk to human health or the environment.  It was incorporated into the evaluation phase of the site mitigation process to establish a mechanism for determining if known or potential hazardous substance sites require immediate or long-term remedial actions by DTSC or with DTSC oversight.

PRESSURE WASHER (COLD WATER):

Steam cleaner with out steam (decontamination unit).

PROJECT AREA COMMITTEE (PAC):

A PAC is a committee elected by and composed of residential owners and tenants, business owners and existing community organizations in a redevelopment project area. If a PAC is required to be formed, a redevelopment agency must consult with the PAC during and after the plan adoption process.

PROSPECTIVE PURCHASER AGREEMENT:

Expands the circumstances under which an environmental regulator will serve and agree not to sue a buyer of a property for existing contamination in exchange for an appropriate cash or work contribution to the clean up of the property, or indirect benefits such as potential environmental improvements, economic and social factors such as jobs, infrastructure, increased tax base, and opportunities for disadvantaged groups. An agreement between U.S. EPA and a buyer interested in a brownfields site whereby the agency promises not to pursue enforcement against the site if certain conditions are met.

PUBLIC SUPPLY:

Water withdrawn by public governments and agencies, such as a county water department, and by private companies that is then delivered to users. Public suppliers provide water for domestic, commercial, thermoelectric power, industrial, and public water users. Most people's household water is delivered by a public water supplier. The systems have at least 15 service connections (such as households, businesses, or schools) or regularly serve at least 25 individuals daily for at least 60 days out of the year. 

PUMP AND TREAT:

A technique that brings contaminated groundwater above the ground through the use of extraction wells. The water is then treated, normally using one of the three processes: granulated activated carbon, air stripping, or bioremediation.

PUMP TEST:

A field test by which a well is pumped for a period of time and data are collected for use in assessing characteristics of subsurface water-bearing zones, or aquifers.

PUMPS:

A variety of devices used to move water to another location usually from a well.

PVC SCREEN:

PVC Pipe with holes or slots along its length that allow fluid to enter.