Copy of `EPA - Environmental Terms Glossary`

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EPA - Environmental Terms Glossary Category: Earth and Environment Date & country: 13/09/2007, USA Words: 1829

Transpiration
The process by which water vapor is lost to the atmosphere from living plants. The term can also be applied to the quantity of water thus dissipated.

Transporter
Hauling firm that picks up properly packaged and labeled hazardous waste from generators and transports it to designated facilities for treatment, storage, or disposal. Transporters are subject to EPA and DOT hazardous waste regulations.

Trash
Material considered worthless or offensive that is thrown away. Generally defined as dry waste material, but in common usage it is a synonym for garbage, rubbish, or refuse.

Trash-to-Energy Plan
Burning trash to produce energy.

Treatability Studies
Tests of potential cleanup technologies conducted in a laboratory (See bench-scale tests.)

Treated Regulated Medical Waste
Medical waste treated to substantially reduce or eliminate its pathogenicity, but that has not yet been destroyed.

Treated Wastewater
Wastewater that has been subjected to one or more physical, chemical, and biological processes to reduce its potential of being health hazard.

Treatment
(1) Any method, technique, or process designed to remove solids and/or pollutants from solid waste, waste-streams, effluents, and air emissions. (2) Methods used to change the biological character or composition of any regulated medical waste so as to substantially reduce or eliminate its potential for causing disease.

Treatment Plant
A structure built to treat wastewater before discharging it into the environment.

Tremie
Device used to place concrete or grout under water.

Trial Burn
An incinerator test in which emissions are monitored for the presence of specific organic compounds, particulates, and hydrogen chloride.

Trichloroethylene (TCE)
A stable, low boiling-point colorless liquid, toxic if inhaled. Used as a solvent or metal degreasing agent, and in other industrial applications.

Trickle Irrigation
Method in which water drips to the soil from perforated tubes or emitters.

Trickling Filter
A coarse treatment system in which wastewater is trickled over a bed of stones or other material covered with bacteria that break down the organic waste and produce clean water.

Trihalomethane (THM)
One of a family of organic compounds named as derivative of methane. THMs are generally by-products of chlorination of drinking water that contains organic material.

Troposhpere
The layer of the atmosphere closest to the earth's surface.

Trust Fund (CERCLA)
A fund set up under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) to help pay for cleanup of hazardous waste sites and for legal action to force those responsible for the sites to clean them up.

Tube Settler
Device using bundles of tubes to let solids in water settle to the bottom for removal by conventional sludge collection means; sometimes used in sedimentation basins and clarifiers to improve particle removal.

Tuberculation
Development or formation of small mounds of corrosion products on the inside of iron pipe. These tubercules roughen the inside of the pipe, increasing its resistance to water flow.

Tundra
A type of treeless ecosystem dominated by lichens, mosses, grasses, and woody plants. Tundra is found at high latitudes (arctic tundra) and high altitudes (alpine tundra). Arctic tundra is underlain by permafrost and is usually water saturated. (See wetlands.)

Turbidimeter
A device that measures the cloudiness of suspended solids in a liquid; a measure of the quantity of suspended solids.

Turbidity
1. Haziness in air caused by the presence of particles and pollutants. 2. A cloudy condition in water due to suspended silt or organic matter.

Ultra Clean Coal (UCC)
Coal that is washed, ground into fine particles, then chemically treated to remove sulfur, ash, silicone, and other substances; usually briquetted and coated with a sealant made from coal.

Ultraviolet Rays
Radiation from the sun that can be useful or potentially harmful. UV rays from one part of the spectrum (UV-A) enhance plant life. UV rays from other parts of the spectrum (UV-B) can cause skin cancer or other tissue damage. The ozone layer in the atmosphere partly shields us from ultraviolet rays reaching the earth's surface.

Uncertainty Factor
One of several factors used in calculating the reference dose from experimental data. UFs are intended to account for (1) the variation in sensitivity among humans; (2) the uncertainty in extrapolating animal data to humans; (3) the uncertainty in extrapolating data obtained in a study that covers less than the full life of the exposed animal or human; and (4) the uncertainty in using LOAEL data rather than NOAEL data.

Unconfined Aquifer
An aquifer containing water that is not under pressure; the water level in a well is the same as the water table outside the well.

Underground Injection Control (UIC)
The program under the Safe Drinking Water Act that regulates the use of wells to pump fluids into the ground.

Underground Injection Wells
Steel- and concrete-encased shafts into which hazardous waste is deposited by force and under pressure.

Underground Storage Tank (UST)
A tank located at least partially underground and designed to hold gasoline or other petroleum products or chemicals.

Unreasonable Risk
Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), 'unreasonable adverse effects' means any unreasonable risk to man or the environment, taking into account the medical, economic, social, and environmental costs and benefits of any pesticide.

Unsaturated Zone
The area above the water table where soil pores are not fully saturated, although some water may be present.

Upper Detection Limit
The largest concentration that an instrument can reliably detect.

Uranium Mill Tailings Piles
Former uranium ore processing sites that contain leftover radioactive materials (wastes), including radium and unrecovered uranium.

Uranium Mill-Tailings Waste Piles
Licensed active mills with tailings piles and evaporation ponds created by acid or alkaline leaching processes.

Urban Runoff
Storm water from city streets and adjacent domestic or commercial properties that carries pollutants of various kinds into the sewer systems and receiving waters.

Urea-Formaldehyde Foam Insulation
A material once used to conserve energy by sealing crawl spaces, attics, etc.; no longer used because emissions were found to be a health hazard.

Use Cluster
A set of competing chemicals, processes, and/or technologies that can substitute for one another in performing a particular function.

Used Oil
Spent motor oil from passenger cars and trucks collected at specified locations for recycling (not included in the category of municipal solid waste).

User Fee
Fee collected from only those persons who use a particular service, as compared to one collected from the public in general.

Utility Load
The total electricity demand for a utility district.

Vadose Zone
The zone between land surface and the water table within which the moisture content is less than saturation (except in the capillary fringe) and pressure is less than atmospheric. Soil pore space also typically contains air or other gases. The capillary fringe is included in the vadose zone. (See Unsaturated Zone.)

Vapor
The gas given off by substances that are solids or liquids at ordinary atmospheric pressure and temperatures.

Vapor Capture System
Any combination of hoods and ventilation system that captures or contains organic vapors so they may be directed to an abatement or recovery device.

Vapor Dispersion
The movement of vapor clouds in air due to wind, thermal action, gravity spreading, and mixing.

Vapor Plumes
Flue gases visible because they contain water droplets.

Vapor Pressure
A measure of a substance's propensity to evaporate, vapor pressure is the force per unit area exerted by vapor in an equilibrium state with surroundings at a given pressure. It increases exponentially with an increase in temperature. A relative measure of chemical volatility, vapor pressure is used to calculate water partition coefficients and volatilization rate constants.

Vapor Recovery System
A system by which the volatile gases from gasoline are captured instead of being released into the atmosphere.

Variance
Government permission for a delay or exception in the application of a given law, ordinance, or regulation.

Vector
1. An organism, often an insect or rodent, that carries disease. 2. Plasmids, viruses, or bacteria used to transport genes into a host cell. A gene is placed in the vector; the vector then 'infects' the bacterium.

Vegetative Controls
Non-point source pollution control practices that involve vegetative cover to reduce erosion and minimize loss of pollutants.

Vehicle Miles Travelled (VMT)
A measure of the extent of motor vehicle operation; the total number of vehicle miles travelled within a specific geographic area over a given period of time.

Ventilation Rate
The rate at which indoor air enters and leaves a building. Expressed as the number of changes of outdoor air per unit of time (air changes per hour (ACH), or the rate at which a volume of outdoor air enters in cubic feet per minute (CFM).

Ventilation-Suction
The act of admitting fresh air into a space in order to replace stale or contaminated air; achieved by blowing air into the space. Similarly, suction represents the admission of fresh air into an interior space by lowering the pressure outside of the space, thereby drawing the contaminated air outward.

Venturi Scrubbers
Air pollution control devices that use water to remove particulate matter from emissions.

Vinyl Chloride
A chemical compound, used in producing some plastics, that is believed to be oncogenic.

Virgin Materials
Resources extracted from nature in their raw form, such as timber or metal ore.

Viscosity
The molecular friction within a fluid that produces flow resistance.

Volatile
Any substance that evaporates readily.

Volatile Liquids
Liquids which easily vaporize or evaporate at room temperature.

Volatile Organic Compound (VOC)
Any organic compound that participates in atmospheric photochemical reactions except those designated by EPA as having negligible photochemical reactivity.

Volatile Solids
Those solids in water or other liquids that are lost on ignition of the dry solids at 550° centigrade.

Volume Reduction
Processing waste materials to decrease the amount of space they occupy, usually by compacting, shredding, incineration, or composting.

Volumetric Tank Test
One of several tests to determine the physical integrity of a storage tank; the volume of fluid in the tank is measured directly or calculated from product-level changes. A marked drop in volume indicates a leak.

Vulnerability Analysis
Assessment of elements in the community that are susceptible to damage if hazardous materials are released.

Vulnerable Zone
An area over which the airborne concentration of a chemical accidentally released could reach the level of concern.

Waste
1. Unwanted materials left over from a manufacturing process. 2. Refuse from places of human or animal habitation.

Waste Characterization
Identification of chemical and microbiological constituents of a waste material.

Waste Exchange
Arrangement in which companies exchange their wastes for the benefit of both parties.

Waste Feed
The continuous or intermittent flow of wastes into an incinerator.

Waste Generation
The weight or volume of materials and products that enter the waste stream before recycling, composting, landfilling, or combustion takes place. Also can represent the amount of waste generated by a given source or category of sources.

Waste Load Allocation
1. The maximum load of pollutants each discharger of waste is allowed to release into a particular waterway. Discharge limits are usually required for each specific water quality criterion being, or expected to be, violated. 2. The portion of a stream's total assimilative capacity assigned to an individual discharge.

Waste Minimization
Measures or techniques that reduce the amount of wastes generated during industrial production processes; term is also applied to recycling and other efforts to reduce the amount of waste going into the waste stream.

Waste Piles
Non-containerized, lined or unlined accumulations of solid, nonflowing waste.

Waste Reduction
Using source reduction, recycling, or composting to prevent or reduce waste generation.

Waste Stream
The total flow of solid waste from homes, businesses, institutions, and manufacturing plants that is recycled, burned, or disposed of in landfills, or segments thereof such as the 'residential waste stream' or the 'recyclable waste stream.'

Waste Treatment Lagoon
Impoundment made by excavation or earth fill for biological treatment of wastewater.

Waste Treatment Plant
A facility containing a series of tanks, screens, filters and other processes by which pollutants are removed from water.

Waste Treatment Stream
The continuous movement of waste from generator to treater and disposer.

Waste-Heat Recovery
Recovering heat discharged as a byproduct of one process to provide heat needed by a second process.

Wastewater
The spent or used water from a home, community, farm, or industry that contains dissolved or suspended matter.Water Pollution The presence in water of enough harmful or objectionable material to damage the water's quality

Wastewater Infrastructure
The plan or network for the collection, treatment, and disposal of sewage in a community. The level of treatment will depend on the size of the community, the type of discharge, and/or the designated use of the receiving water.

Wastewater Treatment Plan
A facility containing a series of tanks, screens, filters, and other processes by which pollutants are removed from water. Most treatments include chlorination to attain safe drinking water standards.

Water Purveyor
A public utility, mutual water company, county water district, or municipality that delivers drinking water to customers.

Water Quality Criteria
Levels of water quality expected to render a body of water suitable for its designated use. Criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.

Water Quality Standards
State-adopted and EPA-approved ambient standards for water bodies. The standards prescribe the use of the water body and establish the water quality criteria that must be met to protect designated uses.

Water Quality-Based Limitations
Effluent limitations applied to dischargers when mere technology-based limitations would cause violations of water quality standards. Usually applied to discharges into small streams.

Water Quality-Based Permit
A permit with an effluent limit more stringent than one based on technology performance. Such limits may be necessary to protect the designated use of receiving waters (e.g. recreation, irrigation, industry or water supply).

Water Solubility
The maximum possible concentration of a chemical compound dissolved in water. If a substance is water soluble it can very readily disperse through the environment.

Water Storage Pond
An impound for liquid wastes designed to accomplish some degree of biochemical treatment.

Water Supplier
One who owns or operates a public water system.

Water Supply System
The collection, treatment, storage, and distribution of potable water from source to consumer.

Water Table
The level of groundwater.

Water Treatment Lagoon
An impound for liquid wastes designed to accomplish some degree of biochemical treatment.

Water Well
An excavation where the intended use is for location, acquisition, development, or artificial recharge of ground water.

Water-Soluble Packaging
Packaging that dissolves in water; used to reduce exposure risks to pesticide mixers and loaders.

Water-Source Heat Pump
Heat pump that uses wells or heat exchangers to transfer heat from water to the inside of a building. Most such units use ground water. (See

Waterborne Disease Outbreak
The significant occurence of acute illness associated with drinking water from a public water system that is deficient in treatment, as determined by appropriate local or state agencies.

Watershed
The land area that drains into a stream; the watershed for a major river may encompass a number of smaller watersheds that ultimately combine at a common point.

Watershed Approach
A coordinated framework for environmental management that focuses public and private efforts on the highest priority problems within hydrologically-defined geographic areas taking into consideration both ground and surface water flow.

Watershed Area
A topographic area within a line drawn connecting the highest points uphill of a drinking waterintake into which overland flow drains.