This glossary contains terms you may run across on this site or in some other EHS context.
Scrubber: An air pollution control device installed to remove pollutants from an exhaust stream before emission to the atmosphere.
Secondary Treatment: The second step in most publicly owned waste treatment systems in which bacteria consume the organic parts of the waste.
Sewage: The waste and wastewater produced by residential and commercial establishments and discharged into sewers.
Shipping Papers: Document that identifies the hazardous material being transported, shipper prepares for transporter. Shipping papers are a U.S. Department of Transportation requirement. (Shipments of hazardous wastes must be accompanied by the proper state or EPA manifest.)
SIC Code: Standard industrial classification code, a number assigned to various industries by the U.S. Department of Labor. SIC codes help to numerically classify and identify industries; for example, the SIC code for the chemical industry is 28.
Site Inspection: The collection of information from a Superfund site to determine the extent and severity of hazards posed by the site. It is more extensive than a preliminary assessment.
Siting: The process of choosing a location for a facility.
Sludge: A semisolid residue from any of a number of air or water treatment processes. Sludge may be a hazardous waste.
Small Quantity Generator (SQG): A facility generating between 100 and 1,000 kg of hazardous waste, or less than 1 kg of acutely hazardous waste, a month. SQGs are subject to most regulations, except formal training programs, biennial reports, and a written contingency plan (see Conditionally Exempt Generators). For more information, see the Hazardous Waste Generators topic page.
Sole Source Aquifer: An aquifer that supplies 50 percent or more of the drinking water of an area.
Solid Waste: Any garbage, refuse, or sludge, including solid, liquid, semisolid, or contained gaseous material resulting from industrial, commercial, agricultural, and mining operations, and community activities; excluding material in domestic sewage, discharges subject to regulation as point sources under the Federal Water Pollution Control Act, or any nuclear material or by-product regulated under the Atomic Energy Act of 1954. For more information, see the Solid Waste topic page.
Solid Waste Disposal: The final placement of refuse that is not salvaged or recycled. For more information, see the Solid Waste topic page.
Solid Waste Management: Supervised handling of waste materials from their source through recovery processes
to disposal. For more information, see the Solid Waste topic page.
Solid Waste Management Unit: A solid waste management unit (SWMU) is used to treat, store, or dispose of solid (nonhazardous) waste. Examples of SWMUs include containers, tanks, landfills, and land treatment facilities. For more information, see the Solid Waste topic page.
Solvent: Substance (usually liquid) capable of dissolving or dispersing one or more other substances.
Sorption: The action of soaking up or attracting substances. A process used in many pollution control systems.
Spill Prevention Control and Countermeasures Plan (SPCC): Plan covering responses to the release of hazardous substances as defined by the Clean Water Act. For more information, see the Spill Prevention (SPCC Plan) topic page.
Spoil: Dirt or rock that has been removed from its original location destroying the composition of the soil in the process, as with strip mining or dredging.
Standards: Prescriptive norms that govern action and actual limits on the amount of pollutants or emissions produced. EPA establishes minimum standards. States are allowed to be stricter.
State Emergency Response Commission (SERC): Commission appointed by each state governor according to the requirements of SARA Title III. SERCs designate emergency planning districts, appoint local emergency planning committees, and supervise and coordinate their activities.
State Implementation Plan (SIP): EPA-approved state plan for the establishment, regulation, and enforcement of air pollution standards.
Stationary Source: A fixed, unmoving producer of pollution.
Storage: Temporary holding of waste pending treatment or disposal.
Sump: A pit or tank that catches liquid runoff for drainage or disposal.
Sump Pump: A mechanism for removing water or wastewater from a sump or wet well.
Superfund: Commonly used to refer to the program operated under the legislative authority of CERCLA that funds and carries out the EPA solid waste emergency and long-term removal remedial activities. These activities include establishing the National Priorities List, investigating sites for inclusion on the list, determining their priority level on the list, and conducting and/or supervising the ultimately determined cleanup and other remedial actions. More specifically, Superfund is the remediation fund for these cleanups, funded by taxes on chemical feedstocks and petroleum products. Many states also have Superfund laws. For more information, see the Superfund topic page.
Surface Impoundment: Treatment, storage, or disposal of liquid hazardous waste in ponds, lagoons, or pits. For more information, see the Surface Impoundments topic page.
Surface Water: All water naturally open to the atmosphere, and all springs, wells, or other collectors that are directly influenced by surface water.
Surveillance System: A series of monitoring devices designed to determine environmental quality.
25-Year/24-Hour Storm Event: A storm event with a probable reoccurrence interval of once every 25 years as defined by the National Weather Service.
Tank: See Hazardous Waste Storage Tank and Underground Storage Tank.
Technology-Based Standards: Effluent limitations applicable to direct and indirect sources that are developed on a category-by-category basis using statutory factors, not including water-quality effects.
Thermal Pollution: Discharge of heated water from industrial processes that can affect the processes of aquatic organisms.
Thermocline: The stratified layer of a lake that separates the epilimnion from the hypolimnion. It is specifically defined as a stratum in which temperature decreases at the rate of 1°C per each meter of depth.
Threshold Limit Value (TLV): Represents the air concentrations of chemical substances to which it is believed that workers may be daily exposed without adverse effect.
Threshold Planning Quantity (TPQ): A quantity designed 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 under SARA Title III.
Total Suspended Solids (TSS): A measure of the suspended solids in wastewater, effluent, or water bodies, determined by using tests for total suspended nonfilterable solids.
Toxic: Harmful to living organisms.
Toxic Chemical Release Form: Information form required to be submitted by facilities that manufacture, process, or use, in quantities above a specific amount, chemicals listed under SARA Title III. Also known as the Toxic Release Inventory (TRI). For more information, see the Community Right to Know topic page.
Toxic Pollutants: Materials contaminating the environment that cause death, disease, or birth defects in organisms that ingest or absorb them.
Toxic Substance: A chemical or mixture that may present an unreasonable risk of injury to health or the environment.
Toxicity: The degree of danger posed by a substance to animal or plant life.
Transfer Facility: Any transportation-related facility, including loading docks, storage areas, and other similar areas where shipments of hazardous waste are held during the normal course of transportation.
Transport Vehicle: A motor vehicle or rail car used for the transportation of cargo by any mode; each cargo-carrying body (trailer, railroad freight car, etc.) is a separate transport vehicle.
Treatment, Storage, and Disposal Facility (TSDF): Site where a hazardous substance is treated, stored, or disposed. TSDFs are regulated by EPA and states under RCRA. For more information, see the TSDF Responsibilities topic page.
Trust Fund (CERCLA): A fund set up under CERCLA (or equivalent state Superfund law) to help pay for cleanup of hazardous waste sites and for legal action to force those responsible for the sites to clean them up. For more information, see the CERCLA topic page.
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