Cap – A fairly impermeable seal, usually composed of clay-type soil or a combination of clay soil and synthetic liner, which is placed over a landfill during closure. The cap serves to minimize leachate volume during biodegradation of the waste by keeping precipitation from percolating through the land - fill. The cap also keeps odors down and animal scavengers from gathering.

Capacity Assurance Plan – A plan which assures that a state has the ability to treat and dispose of hazardous wastes generated within its borders over the next 20 years. Section 104 of SARA required the first plan to be submitted to EPA in October 1989. But even though capacity has been certified, the state is not required to treat or dispose of hazardous wastes at home; many are exporting to other states that have commercial facilities, permitted landfills, and incinerators. See Law section.

Carcinogenic or Carcinogen – Capable of causing cancer. A suspected carcinogen is a substance that may cause cancer in humans or animals but for which the evidence is not conclusive.

CERCLIS (Pronounced SERK-liss) – The federal Comprehensive Environmental Response, Compensation, and Liability Information System. This database includes all sites which have been nominated for investigation by the Superfund program and the actions that have been taken at these sites. If the site investigation reveals contamination, the site is ranked and may be included on the National Priorities List for Superfund cleanup. Inclusion in the CERCLIS database does not necessarily mean that a property is a hazardous waste site. An emergency action may have been conducted there or a simple investigation which concluded that no further action was required.

Chemical Abstract Service (CAS) – Since the 1890s, CAS has been assigning identification numbers to chemicals that companies register with them. Every year, CAS updates and writes new chemical abstracts on well over a million different chemicals, including their composition, structure, characteristics, and all the different names of that chemical. CAS On-Line is a computer network available to individual and business account holders to receive information about specific chemicals of concern. Each abstract is accompanied by the CAS number.

Chemical Oxygen Demand (COD) – A measure of the oxygen-consuming capacity of inorganic and organic matter present in water or wastewater; the amount of oxygen consumed from a chemical oxidant in a specific test.

Chlorination – Adding chlorine to water or wastewater, generally for the purpose of disinfection, but frequently for accomplishing other biological or chemical results. Chlorine also is used almost universally in manufacturing processes, particularly for the plastics industry.

Chlorofluorocarbons (CFCs) – A family of chemicals commonly used in air conditioners and refrigerators as coolants and also as solvents and aerosol propellants. CFCs drift into the upper atmosphere where their chlorine components destroy ozone. CFCs are thought to be a major cause of the ozone hole over Antarctica.

Chronic Effect – An adverse effect on any living organism in which symptoms develop slowly over a long period of time or recur frequently.

Clear Cut – Essentially all trees have been removed from a stand in one operation. Depending on management objectives, a clearcut may or may not have reserve trees left to attain goals other than regeneration.

Cloning – In biotechnology, obtaining a group of genetically identical cells from a single cell; making identical copies of a gene.

Climate Change – This term is commonly used interchangeably with "global warming" and "the greenhouse effect," but is a more descriptive term. Climate change refers to the buildup of man-made gases in the atmosphere that trap the sun’s heat, causing changes in weather patterns on a global scale. The effects include changes in rainfall patterns, sea level rise, potential droughts, habitat loss, and heat stress. The greenhouse gases of most concern are carbon dioxide, methane, and nitrous oxides. If these gases in our atmosphere double, the earth could warm up by 1.5 to W.5 degrees by the year 2050, with changes in global precipitation having the greatest consequences.

Closure – The procedure an operator must go through when a landfill reaches the legal capacity for solid waste. No more waste can be accepted and a cap usually is placed over the site. The cap is then planted with grasses and other ground covers. Post-closure care includes monitoring ground water, landfill gases, and leachate collection systems, sometimes for as long as 30 years.

Code of Federal Regulations (CFR) – A periodic publication of the regulations established by U.S. law.

Commercial Waste – All solid waste from businesses. This category includes, but is not limited to, solid waste originating in stores, markets, office buildings, restaurants, shopping centers, and theaters.

Commercial Waste Management Facility – A treatment, storage, disposal, or transfer facility that accepts wastes from a variety of sources for profit. A commercial facility manages a broader spectrum of wastes than a private facility, which normally manages a limited volume or type of waste.

Community Relations – Two-way communications with the public to foster understanding of EPA programs and actions and to increase citizen input into EPA decisions. Specific community relations activities such as holding public meetings and comment periods and opening information repositories are required at Superfund sites.

Compost – Decomposed organic material that is produced when bacteria in soil break down garbage and biodegradable trash, making organic fertilizer. Making compost requires turning and mixing and exposing the materials to air. Gardeners and farmers use compost for soil enrichment.

Concentration – The relative amount of a substance mixed with another substance. An example is five parts per million of carbon monoxide in air or 1 milligram/liter of iron in water.

Conditionally Exempt Generators – Small quantity facilities that produce fewer than 220 pounds of hazardous waste per month. Exempt from most regulations, conditionally exempt generators are required to determine whether their waste is hazardous and to notify local waste management agencies. These generators may treat or dispose of the waste on site or ensure that the waste is sent to a permitted disposal or recycling facility.

Cone of Depression – A lowering in the water table that develops around a pumped well.

Construction and Demolition Waste – Waste building materials, dredging materials, tree stumps, and rubble resulting from construction, remodeling, repair, and demolition operations on houses, commercial buildings and other structures, and pavements. May contain lead, asbestos, or other hazardous materials.

Corrosive – A substance that eats or wears away materials gradually by chemical action.

Consent Decree – A legal document submitted by the Department of Justice on behalf of the EPA for approval by a federal judge to settle a case. A consent decree can be used to formalize an agreement reached between EPA and potentially responsible parties (PRPs) for cleanup at a Superfund site. Consent decrees also are signed by regulated facilities to cease or correct certain actions or processes that are polluting the environment and include payment of penalties. The Clean Water Act, Clean Air Act, Toxic Substances Control Act, and others all use consent decrees.

Conservation – Preserving and renewing natural resources to assure their highest economic or social benefit over the longest period of time. Clean rivers and lakes, wilderness areas, a diverse wildlife population, healthy soil, and clean air are natural resources worth conserving for future generations.

Continuous Discharge – A permitted release of pollutants into the environment that occurs without interruption, except for infrequent shutdowns for maintenance, process changes, etc.

Controlled Reaction – A chemical reaction at temperature and pressure conditions that are maintained within safe limits to produce a desired product.

County Emergency Operations Plan – A plan required by Federal Emergency Management Agency regulations that describes actions the county will take to respond to emergency situations such as natural disasters, major fires, transportation incidents, or chemical releases.

Covered Facility – A facility having one or more of the 366+ extremely hazardous substances in amounts higher than the quantity designated by EPCRA. These facilities must file reports with the SERC and LEPC.

Cradle-to-Grave or Manifest System – A procedure in which hazardous wastes are identified as they are produced and are followed through further treatment, transportation, and disposal by a series of permanent, linkable, descriptive documents.

Criteria – Descriptive factors taken into account by EPA in setting standards for pollutants. For example, water quality criteria describe the concentration of pollutants that most fish can be exposed to for an hour without showing acute effects.

Dechlorination – Removal of chlorine and chemical replacement with hydrogen or hydroxide ions to detoxify a substance.

Deep Well Injection – A process by which waste fluids are injected deep below the surface of the earth.

Delist – Use of the petition process (1) to have a chemical’s toxic designation rescinded; (2) to remove a site from the National Priority List; or (3) to exclude a particular waste from regulation even though it is a listed hazardous waste.

Destruction and Removal Efficiency (DRE) – A percentage that represents the number of molecules of a compound removed or destroyed in an incinerator. A DRE of 99.99% means that 9,999 molecules are destroyed for every 10,000 that enter.

Discharge – The release of any waste into the environment from a point source. Usually refers to the release of a liquid waste into a body of water through an outlet such as a pipe, but also refers to air emissions.

Discharge Area – An area of land where there is a net annual transfer of water from the ground water to surface water, such as to streams, springs, lakes, and wetlands.

Dispersion Model – A mathematical prediction of how pollutants from a discharge or emission source will be distributed in the surrounding environment under given conditions of wind, temperature, humidity, and other environmental factors.

Disposal – The discharge, deposit, injection, dumping, spilling, leaking, or placing of any solid waste or hazardous waste into the environment (land, surface water, ground water, and air).

Disposal Facility – A landfill, incinerator, or other facility which receives waste for disposal. The facility may have one or many disposal methods available for use. Does not include wastewater treatment.

Dissolved Oxygen (DO) – Oxygen that is freely available in water to sustain the lives of fish and other aquatic organisms.

Dose – In terms of monitoring exposure levels, the amount of a toxic substance taken into the body over a given period of time.

Dose Response – How an organism’s response to a toxic substance changes as its overall exposure to the substance changes. For example, a small dose of carbon monoxide may cause drowsiness; a large dose can be fatal.

Dump – A land site where wastes are discarded in a disorderly or haphazard fashion without regard to protecting the environment. Uncontrolled dumping is an indiscriminate and illegal form of waste disposal. Problems associated with dumps include multiplication of disease-carrying organisms and pests, fires, air and water pollution, unsightliness, loss of habitat, and personal injury.