Laboratory Terms S

A glossary of science, chemistry, environmental and laboratory terms.

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190 results match your search term:  S


Sacrifical Anode
An easily corroded material deliberately installed in a pipe or intake to giv...

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Safe
Condition of exposure under which there is a practical certainty that no harm...

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Safe Water
Water that does not contain harmful bacteria, toxic materials, or chemicals, ...

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Safe Yield
The annual amount of water that can be taken from a source of supply over a p...

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Safener
A chemical added to a pesticide to keep it from injuring plants.

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Salinity
The percentage of salt in water.

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Salt Water Intrusion
The invasion of fresh surface or ground water by salt water. If it comes from...

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Salts
Minerals that water picks up as it passes through the air, over and under the...

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Salvage
The utilization of waste materials.

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Sampling Frequency
The interval between the collection of successive samples.

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Sanctions
Actions taken by the federal government for failure to provide or implement a...

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Sand Filters
Devices that remove some suspended solids from sewage. Air and bacteria decom...

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Sanitary Sewers
Underground pipes that carry off only domestic or industrial waste, not storm...

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Sanitary Survey
An on-site review of the water sources, facilities, equipment, operation and ...

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Sanitary Water
Water discharged from sinks, showers, kitchens, or other non-industrial opera...

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Sanitation
Control of physical factors in the human environment that could harm developm...

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Saprolite
A soft, clay-rich, thoroughly decomposed rock formed in place by chemical wea...

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Saprophytes
Organisms living on dead or decaying organic matter that help natural decompo...

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Saturated Zone
The area below the water table where all open spaces are filled with water un...

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Saturation
The condition of a liquid when it has taken into solution the maximum possibl...

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Science Advisory Board SAB
A group of external scientists who advise EPA on science and policy.

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Scrap
Materials discarded from manufacturing operations that may be suitable for re...

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Scrap Metal Processor
Intermediate operating facility where recovered metal is sorted, cleaned of c...

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Screening
Use of screens to remove coarse floating and suspended solids from sewage.

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Screening Risk Assessment
A risk assessment performed with few data and many assumptions to identify ex...

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Scrubber
An air pollution device that uses a spray of water or reactant or a dry proce...

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Secondary Drinking Water Regulations
Non-enforceable regulations applying to public water systems and specifying t...

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Secondary Effect
Action of a stressor on supporting components of the ecosystem, which in turn...

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Secondary Materials
Materials that have been manufactured and used at least once and are to be us...

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Secondary Standards
National ambient air quality standards designed to protect welfare, including...

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Secondary Treatment
The second step in most publicly owned waste treatment systems in which bacte...

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Secure Maximum Contaminant Level
Maximum permissible level of a contaminant in water delivered to the free flo...

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Sediment
Topsoil, sand, and minerals washed from the land into water, usually after ra...

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Sediment Yield
The quantity of sediment arriving at a specific location.

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Sedimentation
Letting solids settle out of wastewater by gravity during treatment.

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Sedimentation Tanks
Wastewater tanks in which floating wastes are skimmed off and settled solids ...

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Sediments
Soil, sand, and minerals washed from land into water, usually after rain. The...

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Seed Protectant
A chemical applied before planting to protect seeds and seedlings from diseas...

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Seepage
Percolation of water through the soil from unlined canals, ditches, laterals,...

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Selective Pesticide
A chemical designed to affect only certain types of pests, leaving other plan...

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Semi-Confined Aquifer
An aquifer partially confined by soil layers of low permeability through whic...

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Semivolatile Organic Compounds
Organic compounds that volatilize slowly at standard temperature (20 degrees ...

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Senescence
The aging process. Sometimes used to describe lakes or other bodies of water ...

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Septic System
An on-site system designed to treat and dispose of domestic sewage. A typical...

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Septic Tank
An underground storage tank for wastes from homes not connected to a sewer li...

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Service Connector
The pipe that carries tap water from a public water main to a building.

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Service Line Sample
A one-liter sample of water that has been standing for at least 6 hours in a ...

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Service Pipe
The pipeline extending from the water main to the building served or to the c...

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Set-Back
Setting a thermometer to a lower temperature when the building is unoccupied ...

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Settleable Solids
Material heavy enough to sink to the bottom of a wastewater treatment tank.

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Settling Chamber
A series of screens placed in the way of flue gases to slow the stream of air...

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Settling Tank
A holding area for wastewater, where heavier particles sink to the bottom for...

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Sewage
The waste and wastewater produced by residential and commercial sources and d...

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Sewage Sludge
Sludge produced at a Publicly Owned Treatment Works, the disposal of which is...

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Sewer
A channel or conduit that carries wastewater and storm-water runoff from the ...

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Sewerage
The entire system of sewage collection, treatment, and disposal.

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Shading Coefficient
The amount of the sun's heat transmitted through a given window compared with...

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Shale
Shale is a sedimentary rock that is fine-grained. It has flakes of clay miner...

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Sharps
Hypodermic needles, syringes (with or without the attached needle), Pasteur p...

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Shock Load
The arrival at a water treatment plant of raw water containing unusual amount...

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Short-Circuiting
When some of the water in tanks or basins flows faster than the rest; may res...

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Sick Building Syndrome
Building whose occupants experience acute health and/or comfort effects that ...

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Signal
The volume or product-level change produced by a leak in a tank.

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Signal Words
The words used on a pesticide label--Danger, Warning, Caution--to indicate le...

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Significant Deterioration
Pollution resulting from a new source in previously "clean" areas.

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Significant Municipal Facilities
Those publicly owned sewage treatment plants that discharge a million gallons...

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Significant Non-Compliance
significant violations.)

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Significant Potential Source of Contamination
A facility or activity that stores, uses, or produces compounds with potentia...

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Significant Violations
Violations by point source dischargers of sufficient magnitude or duration to...

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Silt
Sedimentary materials composed of fine or intermediate-sized mineral particles.

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Silviculture
Management of forest land for timber.

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Single-Breath Canister
Small one-liter canister designed to capture a single breath. Used in air pol...

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Sink
Place in the environment where a compound or material collects.

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Sinking
Controlling oil spills by using an agent to trap the oil and sink it to the b...

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SIP Call
EPA action requiring a state to resubmit all or part of its State Implementat...

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Site
An area or place within the jurisdiction of the EPA and/or a state.

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Site Assessment Program
A means of evaluating hazardous waste sites through preliminary assessments a...

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Site Inspection
The collection of information from a Superfund site to determine the extent a...

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Site Remediation
Cleanup techniques used to remove or contain a toxic spill or hazardous mater...

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Site Safety Plan
A crucial element in all removal actions, it includes information on equipmen...

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Siting
The process of choosing a location for a facility.

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Skimming
Using a machine to remove oil or scum from the surface of the water.

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Slow Sand Filtration
Passage of raw water through a bed of sand at low velocity, resulting in subs...

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Sludge
A semi-solid residue from any of a number of air or water treatment processes...

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Sludge Digester
Tank in which complex organic substances like sewage sludges are biologically...

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Slurry
A watery mixture of insoluble matter resulting from some pollution control te...

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Small Quantity Generator
Persons or enterprises that produce 220-2200 pounds per month of hazardous wa...

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Smelter
A facility that melts or fuses ore, often with an accompanying chemical chang...

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Smog
Air pollution typically associated with oxidants.

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Smoke
Particles suspended in air after incomplete combustion.

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Soft Detergents
Cleaning agents that break down in nature.

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Soft Water
Any water that does not contain a significant amount of dissolved minerals su...

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Soil Adsorption Field
A sub-surface area containing a trench or bed with clean stones and a system ...

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Soil and Water Conservation Practices
Control measures consisting of managerial, vegetative, and structural practic...

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Soil Conditioner
An organic material like humus or compost that helps soil absorb water, build...

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Soil Erodibility
An indicator of a soil's susceptibility to raindrop impact, runoff, and other...

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Soil Gas
Gaseous elements and compounds in the small spaces between particles of the e...

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Soil Moisture
The water contained in the pore space of the unsaturated zone.

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Soil Sterilant
A chemical that temporarily or permanently prevents the growth of all plants ...

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Solder
Metallic compound used to seal joints between pipes. Until recently, most sol...

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Sole-Source Aquifer
An aquifer that supplies 50-percent or more of the drinking water of an area.

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Solid Waste
Non-liquid, non-soluble materials ranging from municipal garbage to industria...

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Solid Waste Disposal
The final placement of refuse that is not salvaged or recycled.

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Solid Waste Management
Supervised handling of waste materials from their source through recovery pro...

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Solidification and Stabilization
Removal of wastewater from a waste or changing it chemically to make it less ...

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Solubility
The amount of mass of a compound that will dissolve in a unit volume of solut...

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Soot
Carbon dust formed by incomplete combustion.

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Sorption
The action of soaking up or attracting substances; process used in many pollu...

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Source Area
The location of liquid hydrocarbons or the zone of highest soil or groundwate...

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Source Characterization Measurements
Measurements made to estimate the rate of release of pollutants into the envi...

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Source Reduction
Reducing the amount of materials entering the waste stream from a specific so...

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Source Separation
Segregating various wastes at the point of generation (e.g., separation of pa...

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Source-Water Protection Area
The area delineated by a state for a Public Water Supply or including numerou...

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Sparge or Sparging
Injection of air below the water table to strip dissolved volatile organic co...

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Special Local-Needs Registration
Registration of a pesticide product by a state agency for a specific use that...

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Special Review
Formerly known as Rebuttable Presumption Against Registration (RPAR), this is...

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Special Waste
Items such as household hazardous waste, bulky wastes (refrigerators, pieces ...

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Species
1. A reproductively isolated aggregate of interbreeding organisms having comm...

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Specific Conductance
Rapid method of estimating the dissolved solid content of a water supply by t...

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Specific Yield
The amount of water a unit volume of saturated permeable rock will yield when...

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Spill Prevention Containment and Countermeasures Plan SPCP
Plan covering the release of hazardous substances as defined in the Clean Wat...

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Spoil
Dirt or rock removed from its original location--destroying the composition o...

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Sprawl
Unplanned development of open land.

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Spray Tower Scrubber
A device that sprays alkaline water into a chamber where acid gases are prese...

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Spring
Ground water seeping out of the earth where the water table intersects the gr...

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Spring Melt
The process whereby warm temperatures melt winter snow and ice. Because vario...

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Stabilization
Conversion of the active organic matter in sludge into inert, harmless material.

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Stable Air
A motionless mass of air that holds, instead of dispersing, pollutants.

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Stack
A chimney, smokestack, or vertical pipe that discharges used air.

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Stack Effect
Flow of air resulting from warm air rising, creating a positive pressure area...

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Stage II Controls
Systems placed on service station gasoline pumps to control and capture gasol...

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Stagnation
Lack of motion in a mass of air or water that holds pollutants in place.

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Stakeholder
Any organization, governmental entity, or individual that has a stake in or m...

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Standard Industrial Classification Code
Also known as SIC Codes, a method of grouping industries with similar product...

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Standard Sample
The part of finished drinking water that is examined for the presence of coli...

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Standards
Norms that impose limits on the amount of pollutants or emissions produced. E...

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Start of a Response Action
The point in time when there is a guarantee or set-aside of funding by EPA, o...

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State Emergency Response Commission SERC
Commission appointed by each state governor according to the requirements of ...

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State Environmental Goals and Indication Project
Program to assist state environmental agencies by providing technical and fin...

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State Implementation Plans SIP
EPA approved state plans for the establishment, regulation, and enforcement o...

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State Management Plan
Under FIFRA, a state management plan required by EPA to allow states, tribes,...

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Static Pressure
In flowing air, the total pressure minus velocity pressure, pushing equally i...

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Static Water Depth
The vertical distance from the centerline of the pump discharge down to the s...

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Static Water Level
1. Elevation or level of the water table in a well when the pump is not opera...

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Stationary Source
A fixed-site producer of pollution, mainly power plants and other facilities ...

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Sterilization
The removal or destruction of all microorganisms, including pathogenic and ot...

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Sterilizer
One of three groups of anti-microbials registered by EPA for public health us...

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Storage
Temporary holding of waste pending treatment or disposal, as in containers, t...

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Storm Sewer
A system of pipes (separate from sanitary sewers) that carries water runoff f...

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Stratification
Separating into layers.

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Stratigraphy
Study of the formation, composition, and sequence of sediments, whether conso...

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Stratosphere
The portion of the atmosphere 10-to-25 miles above the earth's surface.

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Stressors
Physical, chemical, or biological entities that can induce adverse effects on...

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Strip-Cropping
Growing crops in a systematic arrangement of strips or bands that serve as ba...

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Strip-Mining
A process that uses machines to scrape soil or rock away from mineral deposit...

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Structural Deformation
Distortion in walls of a tank after liquid has been added or removed.

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Subchronic
Of intermediate duration, usually used to describe studies or periods of expo...

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Subchronic Exposure
Multiple or continuous exposures lasting for approximately ten percent of an ...

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Submerged Aquatic Vegetation
Vegetation that lives at or below the water surface; an important habitat for...

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Subwatershed
Topographic perimeter of the catchment area of a stream tributary.

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Sulfur Dioxide SO2
A pungent, colorless, gasformed primarily by the combustion of fossil fuels; ...

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Summa Canister
A summa canister is a stainless steel electropolished (or "summa" polished) p...

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Sump
A pit or tank that catches liquid runoff for drainage or disposal.

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Superchlorination
Chlorination with doses that are deliberately selected to produce water free ...

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Supercritical Water
A type of thermal treatment using moderate temperatures and high pressures to...

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Superfund
The program operated under the legislative authority of CERCLA and SARA that ...

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Superfund Innovative Technology Evaluation SITE
EPA program to promote development and use of innovative treatment and site c...

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Supplemental Registration
An arrangement whereby a registrant licenses another company to market its pe...

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Supplier of Water
Any person who owns or operates a public water supply.

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Surface Impoundment
Treatment, storage, or disposal of liquid hazardous wastes in ponds.

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Surface Runoff
Precipitation, snow melt, or irrigation water in excess of what can infiltrat...

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Surface Uranium Mines
Strip mining operations for removal of uranium-bearing ore.

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Surface Water
All water naturally open to the atmosphere (rivers, lakes, reservoirs, ponds,...

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Surface-Water Treatment Rule
Rule that specifies maximum contaminant level goals for Giardia lamblia, viru...

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Surfacing ACM
Asbestos-containing material that is sprayed or troweled on or otherwise appl...

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Surfacing Material
Material sprayed or troweled onto structural members (beams, columns, or deck...

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Surfactant
A detergent compound that promotes lathering.

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Surrogate Data
Data from studies of test organisms or a test substance that are used to esti...

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Surveillance System
A series of monitoring devices designed to check on environmental conditions.

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Susceptibility Analysis
An analysis to determine whether a Public Water Supply is subject to signific...

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Suspect Material
Building material suspected of containing asbestos; e.g., surfacing material,...

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Suspended Loads
Specific sediment particles maintained in the water column by turbulence and ...

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Suspended Solids
Small particles of solid pollutants that float on the surface of, or are susp...

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Suspension
Suspending the use of a pesticide when EPA deems it necessary to prevent an i...

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Suspension Culture
Cells growing in a liquid nutrient medium.

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Swamp
A type of wetland dominated by woody vegetation but without appreciable peat ...

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Synergism
An interaction of two or more chemicals that results in an effect greater tha...

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Synthetic Organic Chemicals SOCs
Man-made (anthropogenic) organic chemicals. Some SOCs are volatile; others te...

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System With a Single Service Connection
A system that supplies drinking water to consumers via a single service line.

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Systemic Pesticide
A chemical absorbed by an organism that interacts with the organism and makes...

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