TAD— Technical Assistance
TAG— Technical Assistance Grant
TALMS— Tunable Atomic Line Molecular
TAMS— Toxic Air Monitoring System
TAMTAC— Toxic Air Monitoring System
TAP— Technical Assistance Program
TAPDS— Toxic Air Pollutant Data System
TAS— Tolerance Assessment System
TC— Target Concentration. Technical
Center. Toxicity Characteristics. Toxic Concentration—
TCDD— Dioxin (Tetrachlorodibenzo-p-dioxin)
TCF— Total Chlorine Free
TCLP— Total Concentrate Leachate Procedure.
Toxicity Characteristic Leachate Procedure
TCM— Transportation Control Measure
TCP— Transportation Control Plan; Trichloropropane;
TCRI— Toxic Chemical Release Inventory
TD— Toxic Dose
TDS— Total Dissolved Solids
TEAM— Total Exposure Assessment Model
TEC— Technical Evaluation Committee
TED— Turtle Excluder Devices
TEG— Tetraethylene Glycol
TEGD— Technical Enforcement Guidance
TEL— Tetraethyl Lead
TEM— Texas Episodic Model
TEP— Typical End-use Product. Technical
TERA— TSCA Environmental Release Application
TES— Technical Enforcement Support
TEXIN— Texas Intersection Air Quality
TGO— Total Gross Output
TGAI— Technical Grade of the Active
TGP— Technical Grade Product
THC— Total Hydrocarbons
TI— Temporary Intermittent
TI— Therapeutic Index
TIBL— Thermal Internal Boundary Layer
TIC— Technical Information Coordinator.
Tentatively Identified Compounds
TIM— Technical Information Manager
TIP— Technical Information Package
TIP— Transportation Improvement Program
TIS— Tolerance Index System
TISE— Take It Somewhere Else
TITC— Toxic Substance Control Act Interagency
TLV— Threshold Limit Value
TLV-STEL— TLV-Short Term Exposure Limit
TLV-TWA— TLV-Time Weighted Average
TMDL— Total Maximum Daily Limit; Total
Maximum Daily Load
TMRC— Theoretical Maximum Residue Contribution
TNCWS— Transient Non-Community Water
TO— Task Order
TOA— Trace Organic Analysis
TOC— Total Organic Carbon/ Compound
TP— Technical Product; Total Particulates
TPC— Testing Priorities Committee
TPI— Technical Proposal Instructions
TPQ— Threshold Planning Quantity
TPSIS— Transportation Planning Support
TPY— Tons Per Year
TQM— Total Quality Management
TRC— Technical Review Committee
TRD— Technical Review Document
TRI— Toxic Release Inventory
TRIP— Toxic Release Inventory Program
TRIS— Toxic Chemical Release Inventory
TRLN— Triangle Research Library Network
TRO— Temporary Restraining Order
TSA— Technical Systems Audit
TSCA— Toxic Substances Control Act
TSCATS— TSCA Test Submissions Database
TSCC— Toxic Substances Coordinating
TSD— Technical Support Document
TSDF— Treatment, Storage, and Disposal
TSDG— Toxic Substances Dialogue Group
TSI— Thermal System Insulation
TSM— Transportation System Management
TSO— Time Sharing Option
TSP— Total Suspended Particulates
TSS— Total Suspended (non-filterable)
TTFA— Target Transformation Factor Analysis
TTHM— Total Trihalomethane
TTN— Technology Transfer Network
TTO— Total Toxic Organics
TVA— Tennessee Valley Authority
TVOC— Total Volatile Organic Compounds
TWA— Time Weighted Average
TWS— Transient Water System
TZ— Treatment Zone
Tail Water— The runoff
of irrigation water from the lower end of
an irrigated field.
Tailings— Residue of
raw material or waste separated out during
the processing of crops or mineral ores.
Tailpipe Standards— Emissions
limitations applicable to mobile source engine
negating, or removing pollution control equipment
on a motor vehicle.
Technical Assistance Grant
(TAG)— As part of the Superfund program,
Technical Assistance Grants of up to $50,000
are provided to citizens’ groups to
obtain assistance in interpreting information
related to clean-ups at Superfund sites or
those proposed for the National Priorities
List. Grants are used by such groups to hire
technical advisors to help them understand
the site-related technical information for
the duration of response activities.
Technical-Grade Active Ingredient
(TGA)— A pesticide chemical in pure
form as it is manufactured prior to being
formulated into an end-use product (e.g. wettable
powders, granules, emulsifiable concentrates).
Registered manufactured products composed
of such chemicals are known as Technical Grade
Industry-specific effluent limitations based
on best available preventive technology applied
to a discharge when it will not cause a violation
of water quality standards at low stream flows.
Usually applied to discharges into large rivers.
Industry-specific effluent limitations applicable
to direct and indirect sources which are developed
on a category-by-category basis using statutory
factors, not including water-quality effects.
Teratogenesis— The introduction
of nonhereditary birth defects in a developing
fetus by exogenous factors such as physical
or chemical agents acting in the womb to interfere
with normal embryonic development.
Terracing— Dikes built
along the contour of sloping farm land that
hold runoff and sediment to reduce erosion.
Tertiary Treatment— Advanced
cleaning of wastewater that goes beyond the
secondary or biological stage, removing nutrients
such as phosphorus, nitrogen, and most BOD
and suspended solids.
Theoretical Maximum Residue
Contribution— The theoretical maximum
amount of a pesticide in the daily diet of
an average person. It assumes that the diet
is composed of all food items for which there
are tolerance-level residues of the pesticide.
The TMRC is expressed as milligrams of pesticide/kilograms
of body weight/day.
Therapeutic Index— The
ratio of the dose required to produce toxic
or lethal effects to the dose required to
produce nonadverse or therapeutic response.
Thermal Pollution— Discharge
of heated water from industrial processes
that can kill or injure aquatic organisms.
The formation of layers of different temperatures
in a lake or reservoir.
Thermal System Insulation (TSI)—
Asbestos-containing material applied to pipes,
fittings, boilers, breeching, tanks, ducts,
or other interior structural components to
prevent heat loss or gain or water condensation.
Thermal Treatment— Use
of elevated temperatures to treat hazardous
Thermocline— The middle
layer of a thermally stratified lake or reservoir.
In this layer, there is a rapid decrease in
temperatures in a lake or reservoir.
Threshold— The lowest
dose of a chemical at which a specified measurable
effect is observed and below which it is not
Threshold— The dose or
exposure level below which a significant adverse
effect is not expected.
Threshold Level— Time-weighted
average pollutant concentration values, exposure
beyond which is likely to adversely affect
Threshold Limit Value (TLV)—
The concentration of an airborne substance
to which an average person can be repeatedly
exposed without adverse effects. TLVs may
be expressed in three ways— (1) TLV-TWA—Time
weighted average, based on an allowable exposure
averaged over a normal 8-hour workday or 40-hour
work- week; (2) TLV-STEL—Short-term
exposure limit or maximum concentration for
a brief specified period of time, depending
on a specific chemical (TWA must still be
met); and (3) TLV-C—Ceiling Exposure
Limit or maximum exposure concentration not
to be exceeded under any circumstances. (TWA
must still be met.)
Threshold Planning Quantity—
A quantity designated for each chemical on
the list of extremely hazardous substances
that triggers notification by facilities to
the State Emergency Response Commission that
such facilities are subject to emergency planning
requirements under SARA Title III.
Thropic Levels— A functional
classification of species that is based on
feeding relationships (e.g. generally aquatic
and terrestrial green plants comprise the
first thropic level, and herbivores comprise
Tidal Marsh— Low, flat
marshlands traversed by channels and tidal
hollows, subject to tidal inundation; normally,
the only vegetation present is salt-tolerant
bushes and grasses.
Tillage— Plowing, seedbed
preparation, and cultivation practices.
Time-weighted Average (TWA)—
In air sampling, the average air concentration
of contaminants during a given period.
Tire Processor— Intermediate
operating facility where recovered tires are
processed in preparation for recycling.
Tires— As used in recycling,
passenger car and truck tires (excludes airplane,
bus, motorcycle and special service military,
agricultural, off-the-road and-slow speed
industrial tires). Car and truck tires are
recycled into rubber products such as trash
cans, storage containers, rubberized asphalt
or used whole for playground and reef construction.
Tolerance Petition— A
formal request to establish a new tolerance
or modify an existing one.
residue levels for pesticides in raw agricultural
produce and processed foods. Whenever a pesticide
is registered for use on a food or a feed
crop, a tolerance (or exemption from the tolerance
requirement) must be established. EPA establishes
the tolerance levels, which are enforced by
the Food and Drug Administration and the Department
Tonnage— The amount of
waste that a landfill accepts, usually expressed
in tons per month. The rate at which a landfill
accepts waste is limited by the landfill’s
Topography— The physical
features of a surface area including relative
elevations and the position of natural and
man-made (anthropogenic) features.
Total Dissolved Phosphorous—
The total phosphorous content of all material
that will pass through a filter, which is
determined as orthophosphate without prior
digestion or hydrolysis. Also called soluble
P. or ortho P.
Total Dissolved Solids (TDS)—
All material that passes the standard glass
river filter; now called total filtrable residue.
Term is used to reflect salinity.
Total Petroleum Hydrocarbons
(TPH)— Measure of the concentration
or mass of petroleum hydrocarbon constituents
present in a given amount of soil or water.
The word “total” is a misnomer—few,
if any, of the procedures for quantifying
hydrocarbons can measure all of them in a
given sample. Volatile ones are usually lost
in the process and not quantified and non-petroleum
hydrocarbons sometimes appear in the analysis.
Total Recovered Petroleum Hydrocarbon—
A method for measuring petroleum hydrocarbons
in samples of soil or water.
Total Suspended Particles (TSP)—
A method of monitoring airborne particulate
matter by total weight.
Total Suspended Solids (TSS)—
A measure of the suspended solids in wastewater,
effluent, or water bodies, determined by tests
for “total suspended non-filterable
Toxaphene— Chemical that
causes adverse health effects in domestic
water supplies and is toxic to fresh water
and marine aquatic life.
Toxic Chemical— Any chemical
listed in EPA rules as “Toxic Chemicals
Subject to Section 313 of the Emergency Planning
and Community Right-to-Know Act of 1986.”
Toxic Chemical Release Form—
Information form required of facilities that
manufacture, process, or use (in quantities
above a specific amount) chemicals listed
under SARA Title III.
Toxic Chemical Use Substitution—
Replacing toxic chemicals with less harmful
chemicals in industrial processes.
Toxic Cloud— Airborne
plume of gases, vapors, fumes, or aerosols
containing toxic materials.
The concentration at which a substance produces
a toxic effect.
Toxic Dose— The dose
level at which a substance produces a toxic
Toxic Pollutants— Materials
that cause death, disease, or birth defects
in organisms that ingest or absorb them. The
quantities and exposures necessary to cause
these effects can vary widely.
Toxic Release Inventory—
Database of toxic releases in the United States
compiled from SARA Title III Section 313 reports.
Toxic Substance— A chemical
or mixture that may present an unreasonable
risk of injury to health or the environment.
Toxic Waste— A waste
that can produce injury if inhaled, swallowed,
or absorbed through the skin.
Toxicant— A harmful substance
or agent that may injure an exposed organism.
Toxicity— The degree
to which a substance or mixture of substances
can harm humans or animals. Acute toxicity
involves harmful effects in an organism through
a single or short-term exposure. Chronic toxicity
is the ability of a substance or mixture of
substances to cause harmful effects over an
extended period, usually upon repeated or
continuous exposure sometimes lasting for
the entire life of the exposed organism. Subchronic
toxicity is the ability of the substance to
cause effects for more than one year but less
than the lifetime of the exposed organism.
Characterization of the toxicological properties
and effects of a chemical, with special emphasis
on establishment of dose-response characteristics.
Toxicity Testing— Biological
testing (usually with an invertebrate, fish,
or small mammal) to determine the adverse
effects of a compound or effluent.
An examination, summary, and interpretation
of a hazardous substance to determine levels
of exposure and associated health effects.
Air pollution that travels from one jurisdiction
to another, often crossing state or international
boundaries. Also applies to water pollution.
Transfer Station— Facility
where solid waste is transferred from collection
vehicles to larger trucks or rail cars for
longer distance transport.
Transient Water System—
A non-community water system that does not
serve 25 of the same nonresidents per day
for more than six months per year.
Transmission Lines— Pipelines
that transport raw water from its source to
a water treatment plant, then to the distribution
Transmissivity— The ability
of an aquifer to transmit water.
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.
Transportation Control Measures
(TCMs)— Steps taken by a locality to
reduce vehicular emission and improve air
quality by reducing or changing the flow of
traffic; e.g. bus and HOV lanes, carpooling
and other forms of ride-shairing, public transit,
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.
Burning trash to produce energy.
Tests of potential cleanup technologies conducted
in a laboratory
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.
Treatment, Storage, and Disposal
Facility— Site where a hazardous substance
is treated, stored, or disposed of. TSD facilities
are regulated by EPA and states under RCRA.
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.
A stable, low boiling-point colorless liquid,
toxic if inhaled. Used as a solvent or metal
degreasing agent, and in other industrial
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.
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
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
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.
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.