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Glossary: S
Sacrificial Anode:
An easily corroded material deliberately installed in a pipe or intake to give
it up (sacrifice it) to corrosion while the rest of the water supply facility
remains relatively corrosion-free.
Safe:
Condition of exposure under which there is a practical certainty that no harm
will result to exposed individuals.
Safe Water:
Water that does not contain harmful bacteria, toxic materials, or chemicals, and
is considered safe for drinking even if it may have taste, odor, color, and
certain mineral problems.
Safe Yield:
The annual amount of water that can be taken from a source of supply over a
period of years without depleting that source beyond its ability to be
replenished naturally in "wet years."
Salinity:
The percentage of salt in water.
Salt Water Intrusion:
The invasion of fresh surface or groundwater by salt water. If it comes from the
ocean it may be called sea water intrusion.
Salts:
Minerals that water picks up as it passes through the air, over and under the
ground, or from households and industry.
Salvage:
The utilization of waste materials.
Sampling Frequency:
The interval between the collection of successive samples.
Sanctions:
Actions taken by the federal government for failure to provide or implement a
State Implementation Plan (SIP). Such action may include withholding of highway
funds and a ban on construction of new sources of potential pollution.
Sand Filters:
Devices that remove some suspended solids from sewage. Air and bacteria
decompose additional wastes filtering through the sand so that cleaner water
drains from the bed.
Sanitary Landfill:
(See: landfills.)
Sanitary Sewers:
Underground pipes that carry off only domestic or industrial waste, not storm
water.
Sanitary Survey:
An on-site review of the water sources, facilities, equipment, operation and
maintenance of a public water system to evaluate the adequacy of those elements
for producing and distributing safe drinking water.
Sanitary Water (Also known as gray water):
Water discharged from sinks, showers, kitchens, or other non-industrial
operations, but not from commodes.
Sanitation:
Control of physical factors in the human environment that could harm
development, health, or survival.
Saprolite:
A soft, clay-rich, thoroughly decomposed rock formed in place by chemical
weathering of igneous or metamorphic rock. Forms in humid, tropical, or
subtropical climates.
Saprophytes:
Organisms living on dead or decaying organic matter that help natural
decomposition of organic matter in water.
Saturated Zone:
The area below the water table where all open spaces are filled with water under
pressure equal to or greater than that of the atmosphere.
Saturation:
The condition of a liquid when it has taken into solution the maximum possible
quantity of a given substance at a given temperature and pressure.
Science Advisory Board (SAB):
A group of external scientists who advise USEPA on science and policy.
Scrap:
Materials discarded from manufacturing operations that may be suitable for
reprocessing.
Screening:
Use of screens to remove coarse floating and suspended solids from sewage.
Screening Risk Assessment:
A risk assessment performed with few data and many assumptions to identify
exposures that should be evaluated more carefully for potential risk.
Scrubber:
An air pollution device that uses a spray of water or reactant or a dry process
to trap pollutants in emissions.
Secondary Drinking Water Regulations:
Non-enforceable regulations applying to public water systems and specifying the
maximum contamination levels that, in the judgment of USEPA, are required to
protect the public welfare. These regulations apply to any contaminants that may
adversely affect the odor or appearance of such water and consequently may cause
people served by the system to discontinue its use.
Secondary Effect:
Action of a stressor on supporting components of the ecosystem, which in turn
impact the ecological component of concern. (See: primary effect.)
Secondary Materials:
Materials that have been manufactured and used at least once and are to be used
again.
Secondary Standards:
National ambient air quality standards designed to protect welfare, including
effects on soils, water, crops, vegetation, man-made (anthropogenic) materials,
animals, wildlife, weather, visibility, and climate; damage to property;
transportation hazards; economic values, and personal comfort and well-being.
Secondary Treatment:
The second step in most publicly owned waste treatment systems in which bacteria
consume the organic parts of the waste. It is accomplished by bringing together
waste, bacteria, and oxygen in trickling filters or in the activated sludge
process. This treatment removes floating and settleable solids and about 90
percent of the oxygen-demanding substances and suspended solids. Disinfection is
the final stage of secondary treatment. (See: primary, tertiary treatment.)
Secure Chemical Landfill:
(See: landfills.)
Secure Maximum Contaminant Level:
Maximum permissible level of a contaminant in water delivered to the free
flowing outlet of the ultimate user, or of contamination resulting from
corrosion of piping and plumbing caused by water quality.
Sediment:
Topsoil, sand, and minerals washed from the land into water, usually after rain
or snow melt.
Sediment Yield:
The quantity of sediment arriving at a specific location.
Sedimentation:
Letting solids settle out of wastewater by gravity during treatment.
Sedimentation Tanks:
Wastewater tanks in which floating wastes are skimmed off and settled solids are
removed for disposal.
Sediments:
Soil, sand, and minerals washed from land into water, usually after rain. They
pile up in reservoirs, rivers and harbors, destroying fish and wildlife habitat,
and clouding the water so that sunlight cannot reach aquatic plants. Careless
farming, mining, and building activities will expose sediment materials,
allowing them to wash off the land after rainfall.
Seed Protectant:
A chemical applied before planting to protect seeds and seedlings from disease
or insects.
Seepage:
Percolation of water through the soil from unlined canals, ditches, laterals,
watercourses, or water storage facilities.
Selective Pesticide:
A chemical designed to affect only certain types of pests, leaving other plants
and animals unharmed.
Semi-Confined Aquifer:
An aquifer partially confined by soil layers of low permeability through which
recharge and discharge can still occur.
Semivolatile Organic Compounds:
Organic compounds that volatilize slowly at standard temperature (20 degrees C
and 1 atm pressure).
Senescence:
The aging process. Sometimes used to describe lakes or other bodies of water in
advanced stages of eutrophication. Also used to describe plants and animals.
Septic System:
An on-site system designed to treat and dispose of domestic sewage. A typical
septic system consists of tank that receives waste from a residence or business
and a system of tile lines or a pit for disposal of the liquid effluent (sludge)
that remains after decomposition of the solids by bacteria in the tank and must
be pumped out periodically.
Septic Tank:
An underground storage tank for wastes from homes not connected to a sewer line.
Waste goes directly from the home to the tank. (See: septic system.)
Service Connector:
The pipe that carries tap water from a public water main to a building.
Service Line Sample:
A one-liter sample of water that has been standing for at least 6 hours in a
service pipeline and is collected according to federal regulations.
Service Pipe:
The pipeline extending from the water main to the building served or to the
consumer's system.
Set-Back:
Setting a thermometer to a lower temperature when the building is unoccupied to
reduce consumption of heating energy. Also refers to setting the thermometer to
a higher temperature during unoccupied periods in the cooling season.
Settleable Solids:
Material heavy enough to sink to the bottom of a wastewater treatment tank.
Settling Chamber:
A series of screens placed in the way of flue gases to slow the stream of air,
thus helping gravity to pull particles into a collection device.
Settling Tank:
A holding area for wastewater, where heavier particles sink to the bottom for
removal and disposal.
7Q10:
Seven-day, consecutive low flow with a ten year return frequency; the lowest
stream flow for seven consecutive days that would be expected to occur once in
ten years.
Sewage:
The waste and wastewater produced by residential and commercial sources and
discharged into sewers.
Sewage Lagoon:
(See: lagoon.)
Sewage Sludge:
Sludge produced at a Publicly Owned Treatment Works, the disposal of which is
regulated under the Clean Water Act.
Sewer:
A channel or conduit that carries wastewater and storm-water runoff from the
source to a treatment plant or receiving stream. "Sanitary" sewers carry
household, industrial, and commercial waste. "Storm" sewers carry runoff from
rain or snow. "Combined" sewers handle both.
Sewerage:
The entire system of sewage collection, treatment, and disposal.
Shading Coefficient:
The amount of the sun's heat transmitted through a given window compared with
that of a standard 1/8- inch-thick single pane of glass under the same
conditions.
Sharps:
Hypodermic needles, syringes (with or without the attached needle), Pasteur
pipettes, scalpel blades, blood vials, needles with attached tubing, and culture
dishes used in animal or human patient care or treatment, or in medical,
research or industrial laboratories. Also included are other types of broken or
unbroken glassware that were in contact with infectious agents, such as used
slides and cover slips, and unused hypodermic and suture needles, syringes, and
scalpel blades.
Shock Load:
The arrival at a water treatment plant of raw water containing unusual amounts
of algae, colloidal matter. color, suspended solids, turbidity, or other
pollutants.
Short-Circuiting:
When some of the water in tanks or basins flows faster than the rest; may result
in shorter contact, reaction, or settling times than calculated or presumed.
Sick Building Syndrome:
Building whose occupants experience acute health and/or comfort effects that
appear to be linked to time spent therein, but where no specific illness or
cause can be identified. Complaints may be localized in a particular room or
zone, or may spread throughout the building.
Significant Municipal Facilities:
Those publicly owned sewage treatment plants that discharge a million gallons
per day or more and are therefore considered by states to have the potential to
substantially affect the quality of receiving waters.
Significant Potential Source of Contamination:
A facility or activity that stores, uses, or produces compounds with potential
for significant contaminating impact if released into the source water of a
public water supply.
Significant Violations:
Violations by point source dischargers of sufficient magnitude or duration to be
a regulatory priority.
Silt:
Sedimentary materials composed of fine or intermediate-sized mineral particles.
Silviculture:
Management of forest land for timber.
Single-Breath Canister:
Small one-liter canister designed to capture a single breath. Used in air
pollutant ingestion research.
Sink:
Place in the environment where a compound or material collects.
Sinking:
Controlling oil spills by using an agent to trap the oil and sink it to the
bottom of the body of water where the agent and the oil are biodegraded.
Site:
An area or place within the jurisdiction of the USEPA and/or a state.
Site Assessment Program:
A means of evaluating hazardous waste sites through preliminary assessments and
site inspections to develop a Hazard Ranking System score.
Site Inspection:
The collection of information from a Superfund site to determine the extent and
severity of hazards posed by the site. It follows and is more extensive than a
preliminary assessment. The purpose is to gather information necessary to score
the site, using the Hazard Ranking System, and to determine if it presents an
immediate threat requiring prompt removal.
Site Safety Plan:
A crucial element in all removal actions, it includes information on equipment
being used, precautions to be taken, and steps to take in the event of an
on-site emergency.
Siting:
The process of choosing a location for a facility.
Skimming:
Using a machine to remove oil or scum from the surface of the water.
Slow Sand Filtration:
Passage of raw water through a bed of sand at low velocity, resulting in
substantial removal of chemical and biological contaminants.
Sludge:
A semi-solid residue from any of a number of air or water treatment processes;
can be a hazardous waste.
Sludge Digester:
Tank in which complex organic substances like sewage sludges are biologically
dredged. During these reactions, energy is released and much of the sewage is
converted to methane, carbon dioxide, and water.
Slurry:
A watery mixture of insoluble matter resulting from some pollution control
techniques.
Small Quantity Generator (SQG-sometimes referred to as "Squeegee"):
Persons or enterprises that produce 220-2200 pounds per month of hazardous
waste; they are required to keep more records than conditionally exempt
generators. The largest category of hazardous waste generators, SQGs, include
automotive shops, dry cleaners, photographic developers, and many other small
businesses. (See: conditionally exempt generators.)
Smelter:
A facility that melts or fuses ore, often with an accompanying chemical change,
to separate its metal content. Emissions cause pollution. "Smelting" is the
process involved.
Smog:
Air pollution typically associated with oxidants. (See: photochemical smog.)
Smoke:
Particles suspended in air after incomplete combustion.
Soft Detergents:
Cleaning agents that break down in nature.
Soft Water:
Any water that does not contain a significant amount of dissolved minerals such
as salts of calcium or magnesium.
Soil Adsorption Field:
A sub-surface area containing a trench or bed with clean stones and a system of
piping through which treated sewage may seep into the surrounding soil for
further treatment and disposal.
Soil and Water Conservation Practices:
Control measures consisting of managerial, vegetative, and structural practices
to reduce the loss of soil and water.
Soil Conditioner:
An organic material like humus or compost that helps soil absorb water, build a
bacterial community, and take up mineral nutrients.
Soil Erodibility:
An indicator of a soil's susceptibility to raindrop impact, runoff, and other
erosive processes.
Soil Gas:
Gaseous elements and compounds in the small spaces between particles of the
earth and soil. Such gases can be moved or driven out under pressure.
Soil Moisture:
The water contained in the pore space of the unsaturated zone.
Soil Sterilant:
A chemical that temporarily or permanently prevents the growth of all plants and
animals,
Solder:
Metallic compound used to seal joints between pipes. Until recently, most solder
contained 50 percent lead. Use of solder containing more than 0.2 percent lead
in pipes carrying drinking water is now prohibited.
Sole-Source Aquifer:
An aquifer that supplies 50-percent or more of the drinking water of an area.
Solid Waste:
Non-liquid, non-soluble materials ranging from municipal garbage to industrial
wastes that contain complex and sometimes hazardous substances. Solid wastes
also include sewage sludge, agricultural refuse, demolition wastes, and mining
residues. Technically, solid waste also refers to liquids and gases in
containers.
Solid Waste Disposal:
The final placement of refuse that is not salvaged or recycled.
Solid Waste Management:
Supervised handling of waste materials from their source through recovery
processes to disposal.
Solidification and Stabilization:
Removal of wastewater from a waste or changing it chemically to make it less
permeable and susceptible to transport by water.
Solubility:
The amount of mass of a compound that will dissolve in a unit volume of
solution. Aqueous Solubility is the maximum concentration of a chemical that
will dissolve in pure water at a reference temperature.
Soot:
Carbon dust formed by incomplete combustion.
Sorption:
The action of soaking up or attracting substances; process used in many
pollution control systems.
Source Area:
The location of liquid hydrocarbons or the zone of highest soil or groundwater
concentrations, or both, of the chemical of concern.
Source Characterization Measurements:
Measurements made to estimate the rate of release of pollutants into the
environment from a source such as an incinerator, landfill, etc.
Source Reduction:
Reducing the amount of materials entering the waste stream from a specific
source by redesigning products or patterns of production or consumption (e.g.,
using returnable beverage containers). Synonymous with waste reduction.
Source-Water Protection Area:
The area delineated by a state for a Public Water Supply or including numerous
such suppliers, whether the source is groundwater or surface water or both.
Sparge or Sparging:
Injection of air below the water table to strip dissolved volatile organic
compounds and/or oxygenate groundwater to facilitate aerobic biodegradation of
organic compounds.
Special Waste:
Items such as household hazardous waste, bulky wastes (refrigerators, pieces of
furniture, etc.) tires, and used oil.
Species:
1. A reproductively isolated aggregate of interbreeding organisms having common
attributes and usually designated by a common name.2. An organism belonging to
belonging to such a category.
Specific Conductance:
Rapid method of estimating the dissolved solid content of a water supply by
testing its capacity to carry an electrical current.
Specific Yield:
The amount of water a unit volume of saturated permeable rock will yield when
drained by gravity.
Spill Prevention, Containment, and Countermeasures Plan (SPCP):
Plan covering the release of hazardous substances as defined in the Clean Water
Act.
Spoil:
Dirt or rock removed from its original location--destroying the composition of
the soil in the process--as in strip-mining, dredging, or construction.
Sprawl:
Unplanned development of open land.
Spray Tower Scrubber:
A device that sprays alkaline water into a chamber where acid gases are present
to aid in neutralizing the gas.
Spring:
Groundwater seeping out of the earth where the water table intersects the ground
surface.
Spring Melt/Thaw:
The process whereby warm temperatures melt winter snow and ice. Because various
forms of acid deposition may have been stored in the frozen water, the melt can
result in abnormally large amounts of acidity entering streams and rivers,
sometimes causing fish kills.
Spudder Rig:
(See: Cable Tool Rig)
Stabilization:
Conversion of the active organic matter in sludge into inert, harmless material.
Stabilization Ponds:
(See: lagoon.)
Stable Air:
A motionless mass of air that holds, instead of dispersing, pollutants.
Stack:
A chimney, smokestack, or vertical pipe that discharges used air.
Stack Effect:
Air, as in a chimney, that moves upward because it is warmer than the ambient
atmosphere.
Stack Effect:
Flow of air resulting from warm air rising, creating a positive pressure area at
the top of a building and negative pressure area at the bottom. This effect can
overpower the mechanical system and disrupt building ventilation and air
circulation.
Stack Gas:
(See: flue gas.)
Stage II Controls:
Systems placed on service station gasoline pumps to control and capture gasoline
vapors during refueling.
Stagnation:
Lack of motion in a mass of air or water that holds pollutants in place.
Stakeholder:
Any organization, governmental entity, or individual that has a stake in or may
be impacted by a given approach to environmental regulation, pollution
prevention, energy conservation, etc.
Standard Industrial Classification Code:
Also known as SIC Codes, a method of grouping industries with similar products
or services and assigning codes to these groups.
Standard Sample:
The part of finished drinking water that is examined for the presence of
coliform bacteria.
Standards:
Norms that impose limits on the amount of pollutants or emissions produced.
USEPA establishes minimum standards, but states are allowed to be stricter.
Start of a Response Action:
The point in time when there is a guarantee or set-aside of funding by USEPA,
other federal agencies, states or Principal Responsible Parties in order to
begin response actions at a Superfund site.
State Emergency Response Commission (SERC):
Commission appointed by each state governor according to the requirements of
SARA Title III. The SERCs designate emergency planning districts, appoint local
emergency planning committees, and supervise and coordinate their activities.
State Environmental Goals and Indication Project:
Program to assist state environmental agencies by providing technical and
financial assistance in the development of environmental goals and indicators.
State Implementation Plans (SIP):
USEPA approved state plans for the establishment, regulation, and enforcement of
air pollution standards.
State Management Plan:
Under FIFRA, a state management plan required by USEPA to allow states, tribes,
and U.S. territories the flexibility to design and implement ways to protect
groundwater from the use of certain pesticides.
Static Water Depth:
The vertical distance from the centerline of the pump discharge down to the
surface level of the free pool while no water is being drawn from the pool or
water table.
Static Water Level:
1. Elevation or level of the water table in a well when the pump is not
operating. 2. The level or elevation to which water would rise in a tube
connected to an artesian aquifer or basin in a conduit under pressure.
Stationary Source:
A fixed-site producer of pollution, mainly power plants and other facilities
using industrial combustion processes. (See: point source.)
Sterilization:
The removal or destruction of all microorganisms, including pathogenic and other
bacteria, vegetative forms, and spores.
Sterilizer:
One of three groups of anti-microbials registered by USEPA for public health
uses. USEPA considers an antimicrobial to be a sterilizer when it destroys or
eliminates all forms of bacteria, viruses, and fungi and their spores. Because
spores are considered the most difficult form of microorganism to destroy, USEPA
considers the term sporicide to be synonymous with sterilizer.
Storage:
Temporary holding of waste pending treatment or disposal, as in containers,
tanks, waste piles, and surface impoundments.
Storm Sewer:
A system of pipes (separate from sanitary sewers) that carries water runoff from
buildings and land surfaces.
Stratigraphy:
Study of the formation, composition, and sequence of sediments, whether
consolidated or not.
Stratosphere:
The portion of the atmosphere 10-to-25 miles above the earth's surface.
Stressors:
Physical, chemical, or biological entities that can induce adverse effects on
ecosystems or human health.
Strip-Cropping:
Growing crops in a systematic arrangement of strips or bands that serve as
barriers to wind and water erosion.
Strip-Mining:
A process that uses machines to scrape soil or rock away from mineral deposits
just under the earth's surface.
Structural Deformation:
Distortion in walls of a tank after liquid has been added or removed.
Subchronic:
Of intermediate duration, usually used to describe studies or periods of
exposure lasting between 5 and 90 days.
Subchronic Exposure:
Multiple or continuous exposures lasting for approximately ten percent of an
experimental species lifetime, usually over a three-month period.
Submerged Aquatic Vegetation:
Vegetation that lives at or below the water surface; an important habitat for
young fish and other aquatic organisms.
Subwatershed:
Topographic perimeter of the catchment area of a stream tributary.
Sulfur Dioxide (SO2):
A pungent, colorless, gas formed primarily by the combustion of fossil fuels;
becomes a pollutant when present in large amounts.
Sump:
A pit or tank that catches liquid runoff for drainage or disposal.
Superchlorination:
Chlorination with doses that are deliberately selected to produce water free of
combined residuals so large as to require dechlorination.
Supercritical Water:
A type of thermal treatment using moderate temperatures and high pressures to
enhance the ability of water to break down large organic molecules into smaller,
less toxic ones. Oxygen injected during this process combines with simple
organic compounds to form carbon dioxide and water.
Superfund:
The program operated under the legislative authority of CERCLA and SARA that
funds and carries out USEPA solid waste emergency and long-term removal and
remedial activities. These activities include establishing the National
Priorities List, investigating sites for inclusion on the list, determining
their priority, and conducting and/or supervising cleanup and other remedial
actions.
Superfund Innovative Technology Evaluation (SITE) Program:
USEPA program to promote development and use of innovative treatment and site
characterization technologies in Superfund site cleanups.
Supplemental Registration:
An arrangement whereby a registrant licenses another company to market its
pesticide product under the second company's registration.
Supplier of Water:
Any person who owns or operates a public water supply.
Surface Impoundment:
Treatment, storage, or disposal of liquid hazardous wastes in ponds.
Surface Runoff:
Precipitation, snow melt, or irrigation water in excess of what can infiltrate
the soil surface and be stored in small surface depressions; a major transporter
of non-point source pollutants in rivers, streams, and lakes..
Surface Uranium Mines:
Strip mining operations for removal of uranium-bearing ore.
Surface Water:
All water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds,
streams, impoundments, seas, estuaries, etc.)
Surface-Water Treatment Rule:
Rule that specifies maximum contaminant level goals for Giardia lamblia,
viruses, and Legionella and promulgates filtration and disinfection requirements
for public water systems using surface-water or ground-water sources under the
direct influence of surface water. The regulations also specify water quality,
treatment, and watershed protection criteria under which filtration may be
avoided.
Surfacing ACM:
Asbestos-containing material that is sprayed or troweled on or otherwise applied
to surfaces, such as acoustical plaster on ceilings and fireproofing materials
on structural members.
Surfacing Material:
Material sprayed or troweled onto structural members (beams, columns, or
decking) for fire protection; or on ceilings or walls for fireproofing,
acoustical or decorative purposes. Includes textured plaster, and other textured
wall and ceiling surfaces.
Surfactant:
A detergent compound that promotes lathering.
Surrogate Data:
Data from studies of test organisms or a test substance that are used to
estimate the characteristics or effects on another organism or substance.
Surveillance System:
A series of monitoring devices designed to check on environmental conditions.
Susceptibility Analysis:
An analysis to determine whether a Public Water Supply is subject to significant
pollution from known potential sources.
Suspect Material:
Building material suspected of containing asbestos; e.g., surfacing material,
floor tile, ceiling tile, thermal system insulation.
Suspended Loads:
Specific sediment particles maintained in the water column by turbulence and
carried with the flow of water.
Suspended Solids:
Small particles of solid pollutants that float on the surface of, or are
suspended in, sewage or other liquids. They resist removal by conventional
means.
Suspension:
Suspending the use of a pesticide when USEPA deems it necessary to prevent an
imminent hazard resulting from its continued use. An emergency suspension takes
effect immediately; under an ordinary suspension a registrant can request a
hearing before the suspension goes into effect. Such a hearing process might
take six months.
Suspension Culture:
Cells growing in a liquid nutrient medium.
Swamp:
A type of wetland dominated by woody vegetation but without appreciable peat
deposits. Swamps may be fresh or salt water and tidal or non-tidal. (See:
wetlands.)
Synergism:
An interaction of two or more chemicals that results in an effect greater than
the sum of their separate effects.
Synthetic Organic Chemicals (SOCs):
Man-made (anthropogenic) organic chemicals. Some SOCs are volatile; others tend
to stay dissolved in water instead of evaporating.
System With a Single Service Connection:
A system that supplies drinking water to consumers via a single service line.
Systemic Pesticide:
A chemical absorbed by an organism that interacts with the organism and makes
the organism toxic to pests.
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