OCC— Old corrugated container
OCD— Offshore and Coastal Dispersion
ODP— Ozone-Depleting Potential
ODS— Ozone-Depleting Substances
OECD— Organization for Economic Cooperation
OF— Optional Form
OLTS— On Line Tracking System
O&M— Operations and Maintenance
ORM— Other Regulated Material
ORP— Oxidation-Reduction Potential
OTAG— Ozone Transport Assessment Group
OTC— Ozone Transport Commission
OTR— Ozone Transport Region
Ocean Discharge Waiver—
A variance from Clean Water Act requirements
for discharges into marine waters.
Odor Threshold— The minimum
odor of a water or air sample that can just
be detected after successive dilutions with
odorless water. Also called threshold odor.
OECD Guidelines— Testing
guidelines prepared by the Organization of
Economic and Cooperative Development of the
United Nations. They assist in preparation
of protocols for studies of toxicology, environmental
Off-Site Facility— A
hazardous waste treatment, storage or disposal
area that is located away from the generating
Office Paper— High grade
papers such as copier paper, computer printout,
and stationary almost entirely made of uncoated
chemical pulp, although some ground wood is
used. Such waste is also generated in homes,
schools, and elsewhere.
Offsets— A concept whereby
emissions from proposed new or modified stationary
sources are balanced by reductions from existing
sources to stabilize total emissions.
Offstream Use— Water
withdrawn from surface or groundwater sources
for use at another place.
Oil and Gas Waste— Gas
and oil drilling muds, oil production brines,
and other waste associated with exploration
for, development and production of crude oil
or natural gas.
Widely used precombustion method for reducing
sulfur dioxide emissions from oil-burning
power plants. The oil is treated with hydrogen,
which removes some of the sulfur by forming
hydrogen sulfide gas.
Oil Fingerprinting— A
method that identifies sources of oil and
allows spills to be traced to their source.
Oil Spill— An accidental
or intentional discharge of oil which reaches
bodies of water. Can be controlled by chemical
dispersion, combustion, mechanical containment,
and/or adsorption. Spills from tanks and pipelines
can also occur away from water bodies, contaminating
the soil, getting into sewer systems and threatening
underground water sources.
Oligotrophic Lakes— Deep
clear lakes with few nutrients, little organic
matter and a high dissolved-oxygen level.
On-Scene Coordinator (OSC)—
The predesignated EPA, Coast Guard, or Department
of Defense official who coordinates and directs
Superfund removal actions or Clean Water Act
oil- or hazardous-spill response actions.
On-Site Facility— A hazardous
waste treatment, storage or disposal area
that is located on the generating site.
Onboard Controls— Devices
placed on vehicles to capture gasoline vapor
during refueling and route it to the engines
when the vehicle is starting so that it can
be efficiently burned.
Onconogenicity— The capacity
to induce cancer.
One-hit Model— A mathematical
model based on the biological theory that
a single “hit” of some minimum
critical amount of a carcinogen at a cellular
target such as DNA can start an irreversible
series events leading to a tumor.
Opacity— The amount of
light obscured by particulate pollution in
the air; clear window glass has zero opacity,
a brick wall is 100 percent opaque. Opacity
is an indicator of changes in performance
of particulate control systems.
Open Burning— Uncontrolled
fires in an open dump.
Open Dump— An uncovered
site used for disposal of waste without environmental
Operable Unit— Term for
each of a number of separate activities undertaken
as part of a Superfund site cleanup. A typical
operable unit would be removal of drums and
tanks from the surface of a site.
Conditions specified in a RCRA permit that
dictate how an incinerator must operate as
it burns different waste types. A trial burn
is used to identify operating conditions needed
to meet specified performance standards.
Operation and Maintenance—
1. Activities conducted after a Superfund
site action is completed to ensure that the
action is effective. 2. Actions taken after
construction to ensure that facilities constructed
to treat waste water will be properly operated
and maintained to achieve normative efficiency
levels and prescribed effluent limitations
in an optimum manner. 3. On-going asbestos
management plan in a school or other public
building, including regular inspections, various
methods of maintaining asbestos in place,
and removal when necessary.
Certification of operators of community and
nontransient noncommunity water systems, asbestos
specialists, pesticide applicators, hazardous
waste transporter, and other such specialists
as required by the EPA or a state agency implementing
an EPA-approved environmental regulatory program.
Optimal Corrosion Control Treatment—
An erosion control treatment that minimizes
the lead and copper concentrations at users’
taps while also ensuring that the treatment
does not cause the water system to violate
any national primary drinking water regulations.
Oral Toxicity— Ability
of a pesticide to cause injury when ingested.
Organic— 1. Referring
to or derived from living organisms. 2. In
chemistry, any compound containing carbon.
Naturally occuring (animal or plant-produced
or synthetic) substances containing mainly
carbon, hydrogen, nitrogen, and oxygen.
Organic Matter— Carbonaceous
waste contained in plant or animal matter
and originating from domestic or industrial
Organism— Any form of
animal or plant life.
that contain phosphorus; short-lived, but
some can be toxic when first applied.
Organophyllic— A substance
that easily combines with organic compounds.
compounds used in anti-foulant paints to protect
the hulls of boats and ships, buoys, and pilings
from marine organisms such as barnacles.
Original AHERA Inspection/Original
Inspection/Inspection— Examination of
school buildings arranged by Local Education
Agencies to identify asbestos-containing-materials,
evaluate their condition, and take samples
of materials suspected to contain asbestos;
performed by EPA-accredited inspectors.
Original Generation Point—
Where regulated medical or other material
first becomes waste.
Osmosis— The passage
of a liquid from a weak solution to a more
concentrated solution across a semipermeable
membrane that allows passage of the solvent
(water) but not the dissolved solids.
Other Ferrous Metals—
Recyclable metals from strapping, furniture,
and metal found in tires and consumer electronics
but does not include metals found in construction
materials or cars, locomotives, and ships.
Other Glass— Recyclable
glass from furniture, appliances, and consumer
electronics. Does not include glass from transportation
products (cars trucks or shipping containers)
and construction or demolition debris.
Other Nonferrous Metals—
Recyclable nonferrous metals such as lead,
copper, and zinc from appliances, consumer
electronics, and nonpackaging aluminum products.
Does not include nonferrous metals from industrial
applications and construction and demolition
Other Paper— For Recyclable
paper from books, third-class mail, commercial
printing, paper towels, plates and cups; and
other nonpackaging paper such as posters,
photographic papers, cards and games, milk
cartons, folding boxes, bags, wrapping paper,
and paperboard. Does not include wrapping
paper or shipping cartons.
Other Plastics— Recyclable
plastic from appliances, eating utensils,
plates, containers, toys, and various kinds
of equipment. Does not include heavy-duty
plastics such as yielding materials.
Other Solid Waste— Recyclable
nonhazardous solid wastes, other than municipal
solid waste, covered under Subtitle D of RARA.
Other Wood— Recyclable
wood from furniture, consumer electronics
cabinets, and other nonpackaging wood products.
Does not include lumber and tree stumps recovered
from construction and demolition activities,
and industrial process waste such as shavings
Outdoor Air Supply— Air
brought into a building from outside.
Outfall— The place where
effluent is discharged into receiving waters.
Overburden— Rock and
soil cleared away before mining.
Overdraft— The pumping
of water from a groundwater basin or aquifer
in excess of the supply flowing into the basin;
results in a depletion or “mining”
of the groundwater in the basin.
Overfire Air— Air forced
into the top of an incinerator or boiler to
fan the flames.
Overflow Rate— One of
the guidelines for design of the settling
tanks and clarifers in a treatment plant;
used by plant operators to determine if tanks
and clarifiers are over or under-used.
Overland Flow— A land
application technique that cleanses waste
water by allowing it to flow over a sloped
surface. As the water flows over the surface,
contaminants are absorbed and the water is
collected at the bottom of the slope for reuse.
Oversized Regulated Medical
Waste— Medical waste that is too large
for plastic bags or standard containers.
Overturn— One complete
cycle of top to bottom mixing of previously
stratified water masses. This phenomenon may
occur in spring or fall, or after storms,
and results in uniformity of chemical and
physical properties of water at all depths.
Oxidant— A collective
term for some of the primary constituents
of photochemical smog.
Oxidation Pond— A man-made
(anthropogenic) body of water in which waste
is consumed by bacteria, used most frequently
with other waste-treatment processes; a sewage
Oxidation— The chemical
addition of oxygen to break down pollutants
or organizac waste; e.g., destruction of chemicals
such as cyanides, phenols, and organic sulfur
compounds in sewage by bacterial and chemical
The electric potential required to transfer
electrons from one compound or element (the
oxidant) to another compound (the reductant);
used as a qualitative measure of the state
of oxidation in water treatment systems.
Oxygenated Fuels— Gasoline
which has been blended with alcohols or ethers
that contain oxygen in order to reduce carbon
monoxide and other emissions.
Oxygenated Solvent— An
organic solvent containing oxygen as part
of the molecular structure. Alcohols and ketones
are oxygenated compounds often used as paint
of ozone to water for disinfection or for
taste and odor control. The ozonator is the
device that does this.
Ozone (O3)— Found in
two layers of the atmosphere, the stratosphere
and the troposphere. In the stratosphere (the
atmospheric layer 7 to 10 miles or more above
the earth’s surface) ozone is a natural
form of oxygen that provides a protective
layer shielding the earth from ultraviolet
radiation.In the troposphere (the layer extending
up 7 to 10 miles from the earth’s surface),
ozone is a chemical oxidant and major component
of photochemical smog. It can seriously impair
the respiratory system and is one of the most
wide- spread of all the criteria pollutants
for which the Clean Air Act required EPA to
set standards. Ozone in the troposphere is
produced through complex chemical reactions
of nitrogen oxides, which are among the primary
pollutants emitted by combustion sources;
hydrocarbons, released into the atmosphere
through the combustion, handling and processing
of petroleum products; and sunlight.
Ozone Depletion— Destruction
of the stratospheric ozone layer which shields
the earth from ultraviolet radiation harmful
to life. This destruction of ozone is caused
by the breakdown of certain chlorine and/or
bromine containing compounds (chlorofluorocarbons
or halons), which break down when they reach
the stratosphere and then catalytically destroy
Ozone Hole— A thinning
break in the stratospheric ozone layer. Designation
of amount of such depletion as an “ozone
hole” is made when the detected amount
of depletion exceeds fifty percent. Seasonal
ozone holes have been observed over both the
Antarctic and Arctic regions, part of Canada,
and the extreme northeastern United States.
Ozone Layer— The protective
layer in the atmosphere, about 15 miles above
the ground, that absorbs some of the sun’s
ultraviolet rays, thereby reducing the amount
of potentially harmful radiation that reaches
the earth’s surface.