ClarifierA tank used to remove solids by gravity, to remove colloidal solids by coagulation, and to remove floating oil and scum through skimming.
Class I AreaAny area designated for the most stringent protection from air quality degradation.
Class II AreaAny area where air is cleaner than required by federal air quality standards and designated for a moderate degree of protection from air quality…
Class IVAll other intermittent streams not meeting higher class criteria.
ClayA very fine-grained rock or mineral fragment of any composition that has a diameter of less than 0.002 mm.
Clean Air Act (CAA)(CAA)The Superfund law incorporates those substances listed as hazardous air pollutants under section 112 of the Clean Air Act (CAA) as CERCLA hazardous…
Clean Water Act (CWA)(CWA)The Superfund law incorporates those substances listed as hazardous water pollutants under section 311 (b)(4) of the Clean Water Act (CWA) as CERCLA…
ClearcutThe removal, in a single cutting, of the entire stand of trees within a designated area.
Clearing and grubbingCleaning a site to prepare it for construction. Involves removing debris, structures, shrubbery, trees, obstructions, and objectionable and unsuitable…
ClimateThe prevailing or average weather conditions of a geographic region.
CloneAn exact genetic replica of a specific gene or an entire organism. See Cloning.
Closed BasinA basin draining to some depression or a pond within its area, from which water is lost only by evaporation or percolation.
Closed-loop cooling systemAlso known as a wet closed-cycle cooling system, a system that circulates water between a steam condenser and a cooling tower to cool steam condensate at…
Clovis ComplexCharacteristic of Paleoindian finds located near Clovis, New Mexico, such as specific fluted points.
co-firingThe use of a mixture of two fuels within the same combustion chamber.
co-generationThe technology of producing electric energy and another form of useful energy (usually thermal) for industrial, commercial, or domestic heating or cooling…
Coastal Zone Management ActNational law encouraging states to develop coastal management programs. The act establishes a method for the federal government to approve states´ plans…
CogenerationThe generation of electricity or shaft power by an energy conversion system and the concurrent use of rejected thermal energy from the conversion system…
Coliform bacteriaBacteria whose presence in waste water is an indicator of pollution and of potentially dangerous contamination.
CollectionThe capture or obtaining of plant or animal specimens. This can include obtaining specimens for scientific study, pets, or illegal trade.
CollectorThe component of a solar energy heating system that collects solar radiation, and that contains components to absorb solar radiation and transfer the heat…
ColluviumA general term to include loose rock and soil material that accumulates at the base of a slope as the result of mass wasting processes.
ColorThe sensible perception of hue, value and saturation characteristics of surfaces of window components.
Combined cycleTwo or more generation processes in series or in parallel, configured to optimize the energy output of the system.
Combined Heat and Power (CHP)(CHP)Also called cogeneration, CHP is the use of the waste heat generated by an engine or power station to produce useful heat, typically for heating of a…
Combined-cycle power plantA power plant that uses two thermodynamic cycles to achieve higher overall system efficiency; e.g.
CombustionThe process of burning; the oxidation of a material by applying heat, which unites oxygen with a material or fuel.
Combustion AirAir that provides the necessary oxygen for complete, clean combustion and maximum heating value.
Combustion efficiencyThe actual heat produced by combustion divided by the total heat potential of the fuel consumed.
Combustion GasesThe gaseous byproducts of the combustion of a fuel.
Combustion turbineA turbine that generates power from the combustion of a fuel.
Commercial forest landForested land which is capable of producing new growth at a minimum rate of 20 cubic feet per acre per year, excluding lands withdrawn from timber…
CommunityA political entity that has the authority to adopt and enforce floodplain ordinances for the area under its jurisdiction.
compactAn agreement between states apportioning the water of a river basin to each of the signatory states.
Compact Linear Fresnel Reflector (CLFR)(CLFR)A type of concentrated solar power (CSP) technology similar to a parabolic trough design, where the sun's heat energy is reflected onto a receiver…
CompensationA type of mitigation in which the impacts to a species or habitat are offset by protecting, restoring, or creating suitable habitat elsewhere.
Compensatory mitigation(For purposes of the Clean Water Act Section 404 and Rivers and Harbors Act Section 10 regulatory programs), compensatory mitigation is the restoration…
Composite noise levelA single noise level summed on an energy basis from many noise sources (e.g., Stirling engine, electric generator, cooling fan, and air compressor for a…
Compressed Natural Gas (CNG)(CNG)Natural gas (methane) that has been compressed to a higher pressure gaseous state by a compressor; used in CNG vehicles.
Concentrating (Solar) CollectorA solar collector that uses reflective surfaces to concentrate sunlight onto a small area, where it is absorbed and converted to heat or, in the case of…
Concentrating solar power (CSP) technologies(CSP)Any of a family of solar energy technologies that reflect and concentrate the sun's energy to produce heat that is subsequently used to produce steam to…
ConcentrationAmount of a chemical in a particular volume or weight of air, water, soil, or other medium.
ConcentratorA photovoltaic module, which includes optical components such as lenses (Fresnel lens) to direct and concentrate sunlight onto a solar cell.
CondenserThe device in an air conditioner or heat pump in which the refrigerant condenses from a gas to a liquid when it is depressurized or cooled.
Condensing powerPower generated through a final steam turbine stage where the steam is exhausted into a condenser and cooled to a liquid to be recycled back into a boiler.
Condensing turbineA turbine used for electrical power generation from a minimum amount of steam. To increase plant efficiency, these units can have multiple uncontrolled…
Condensing, controlled extraction turbinesA controlled turbine that bleeds off (condenses) part of the main stream flow at one (single extraction) or two (double extraction) points.
Conditional use permitA permit, with conditions, allowing an approved use on a site outside the appropriate zoning class.
Conditional Use Permit (CUP)(CUP)In California, this is a permit that is required to be obtained from the county government authority in which a solar energy facility is to be located.
Cone of DepressionA depression in the water table that develops around a pumped well.
Consumptive use(1) Any use of water that permanently removes water from the natural stream system.
continuous fermentationA process in which cells or micro-organisms are maintained in culture in the exponential growth phase by the continuous addition of fresh medium that is…
ContrastThe difference between the brightness of an object compared to that of its immediate background.
Contrast levelA description of the relative amount of visual contrast resulting from a change in the visible landscape.
Control plotA plot in which no vegetation will be cut and natural succession will occur. A control plot serves as a baseline to compare other treatments (Early, Mid…
Conventional forest productsAny commercial roundwood product (boards, dimension lumber, pulp and paper products) except fuelwood.
Conversion EfficiencyThe amount of energy produced as a percentage of the amount of energy consumed.
ConveyorA mechanical apparatus for carrying bulk material from place to place; for example, an endless moving belt or a chain of receptacles.
Coppice regenerationThe ability of certain hardwood species to regenerate by producing multiple new shoots from a stump left after harvest.
CoproductsThe potentially useful byproducts of ethanol fermentation process.
CordA stack of wood consisting of 128 cubic feet. A cord has standard dimensions of 4´ x 4´ x 8´ including air space and bark. One cord contains about 1.
Corn stoverResidue materials from harvesting corn consisting of the cob, leaves and stalk.
Corona dischargeElectrical discharge accompanied by ionization of surrounding atmosphere around high-voltage transmission lines, occurring mostly under wet conditions.
Corona/corona noiseThe electrical breakdown of air into charged particles. The phenomenon appears as a bluish-purple glow on the surface of and adjacent to a conductor when…
Corporate average fuel economy (CAFE)(CAFE)Federal standards enacted in 1975 for fuel economy in motor vehicles. The average of city and highway fuel economy test results weighted by a manufacturer…
CorridorA strip of land through which one or more existing or potential facilities may be located.
coverNatural or manmade objects on the bottom of lakes, rivers, or impoundments, especially those that influence fish behavior.
crackingA reduction of molecular weight by breaking bonds, which may be done by thermal, catalytic, or hydrocracking.
CraterA steep-sided, usually circular depression formed by either explosion or collapse at a volcanic vent.
Creep (rate)Relatively slow movement along a fault. It is sometimes called "seismic creep" to distinguish it from the slumping of rock or soil on slopes (which is…
CrescentsQuarter-moon-shaped (hence crescent) artifacts that may have been in the form of blades, scrapers, or projectile points.
Criteria air pollutantsSix common air pollutants for which National Ambient Air Quality Standards (NAAQS) have been established by the U.S.
Critical habitatThe specific area within the geographical area occupied by the species at the time it is listed as endangered or threatened.
Critical habitat unit (CHU)(CHU)Under the Endangered Species Act, critical habitat is defined as "the specific areas within the geographic area occupied by a species on which are found…
Crop treeUsually a conifer tree grown to provide wood products.
Crucial winter rangeThe portion of the winter range to which a wildlife species is confined during periods of heaviest snow cover or that portion of the year-long range which…
CrustaceansAquatic animals with hard external skeletons and segmented limbs, belonging to the class Crustacea; include cladocerans, shrimp, crayfish, fairy shrimp…
Crustal spreading centerA linear zone in the Earth's crust whose opposite sides are moving away from one another.
Cryptogamic soil crustsA soil crust dominated by a community of algae, lichens, or mosses. See also Biological soil crusts
CSPA type of tumor found in breast or prostate tissue. It is often large and bulky and grows quickly.
CuestaAn elongated ridge formed by gently tilting sedimentary strata. The landform has a steep slope (escarpment or cliff) where the strata are exposed on their…
CullAny item of production picked out for rejection because it does not meet certain specifications.
Cull sectionA log cut from a tree that is rejected because of defects making it unsuitable for conventional forest products.
Cull treesLive saw-timber and pole-timber size trees which do not contain a merchantable sawlog due to poor form, quality, or undesirable species.