A-Scale Sound LevelA measurement of sound approximating the sensitivity of the human ear, used t...
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Abandoned WellA well whose use has been permanently discontinued or which is in a state of ...
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AbatementReducing the degree or intensity of, or eliminating, pollution.
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Abatement DebrisWaste from remediation activities.
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Absorbed DoseIn exposure assessment, the amount of a substance that penetrates an exposed ...
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AbsorberAny material that stops ionizing radiation. Lead, concrete, and steel attenua...
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AbsorptionThe process of taking in. The uptake of water, other fluids, or dissolved che...
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Absorption BarrierAny of the exchange sites of the body that permit uptake of various substance...
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Accident SiteThe location of an unexpected occurrence, failure or loss, either at a plant ...
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AcclimatizationThe physiological and behavioral adjustments of an organism to changes in its...
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AcequiaAcequias were important forms of irrigation in the development of agriculture...
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AcidA corrosive substance with a pH less than 7.
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Acid AerosolAcidic liquid or solid particles small enough to become airborne. High concen...
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Acid DepositionA complex chemical and atmospheric phenomenon that occurs when emissions of s...
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Acid Mine DrainageDrainage of water from areas that have been mined for coal or other mineral o...
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Acid Neutralizing CapacityMeasure of ability of a base (e.g. water or soil) to resist changes in pH.
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AcidicThe condition of water or soil that contains a sufficient amount of acid subs...
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Action Levels1. Regulatory levels recommended by EPA for enforcement by FDA and USDA when ...
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Activated CarbonA highly adsorbent form of carbon used to remove odors and toxic substances f...
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Activated SludgeProduct that results when primary effluent is mixed with bacteria-laden sludg...
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ActivatorA chemical added to a pesticide to increase its activity.
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Active IngredientIn any pesticide product, the component that kills, or otherwise controls, ta...
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Activity PlansWritten procedures in a school's asbestos-management plan that detail the ste...
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Acute EffectAn adverse effect on any living organism which results in severe symptoms tha...
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Acute ExposureA single exposure to a toxic substance which may result in severe biological ...
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Acute ToxicityThe ability of a substance to cause severe biological harm or death soon afte...
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AdaptationChanges in an organism's physiological structure or function or habits that a...
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Add-on Control DeviceAn air pollution control device such as carbon absorber or incinerator that r...
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Adequately WetAsbestos containing material that is sufficiently mixed or penetrated with li...
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Administered DoseIn exposure assessment, the amount of a substance given to a test subject (hu...
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Administrative OrderA legal document signed by EPA directing an individual, business, or other en...
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Administrative Order On ConsentA legal agreement signed by EPA and an individual, business, or other entity ...
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Administrative Procedures ActA law that spells out procedures and requirements related to the promulgation...
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Administrative RecordAll documents which EPA considered or relied on in selecting the response act...
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AdsorptionRemoval of a pollutant from air or water by collecting the pollutant on the s...
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AdulterantsChemical impurities or substances that by law do not belong in a food, or pes...
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Adulterated1. Any pesticide whose strength or purity falls below the quality stated on i...
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Advanced TreatmentA level of wastewater treatment more stringent than secondary treatment; requ...
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Advanced Wastewater TreatmentAny treatment of sewage that goes beyond the secondary or biological water tr...
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Adverse Effects DataFIFRA requires a pesticide registrant to submit data to EPA on any studies or...
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AdvisoryA non-regulatory document that communicates risk information to those who may...
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Aerated LagoonA holding and/or treatment pond that speeds up the natural process of biologi...
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AerationA process which promotes biological degradation of organic matter in water. T...
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Aeration TankA chamber used to inject air into water.
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AerobicLife or processes that require, or are not destroyed by, the presence of oxygen.
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Aerobic TreatmentProcess by which microbes decompose complex organic compounds in the presence...
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Aerosol1. Small droplets or particles suspended in the atmosphere, typically contain...
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Affected LandfillUnder the Clean Air Act, landfills that meet criteria for capacity, age, and ...
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Affected Public1.The people who live and/or work near a hazardous waste site. 2. The human p...
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AfterburnerIn incinerator technology, a burner located so that the combustion gases are ...
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Age TankA tank used to store a chemical solution of known concentration for feed to a...
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AgentAny physical, chemical, or biological entity that can be harmful to an organi...
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Agent OrangeA toxic herbicide and defoliant used in the Vietnam conflict, containing 2,4,...
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Agricultural PollutionFarming wastes, including runoff and leaching of pesticides and fertilizers; ...
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Agricultural WastePoultry and livestock manure, and residual materials in liquid or solid form ...
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AgroecosystemLand used for crops, pasture, and livestock; the adjacent uncultivated land t...
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AHERA Designated Person ADPA person designated by a Local Education Agency to ensure that the AHERA requ...
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AirThe surface between the vadose zone and ambient oil; the pressure of oil in t...
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Air BindingSituation where air enters the filter media and harms both the filtration and...
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Air Changes Per Hour ACHThe movement of a volume of air in a given period of time; if a house has one...
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Air CleaningIndoor-air quality-control strategy to remove various airborne particulates a...
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Air ContaminantAny particulate matter, gas, or combination thereof, other than water vapor.
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Air CurtainA method of containing oil spills. Air bubbling through a perforated pipe cau...
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Air Exchange RateThe rate at which outside air replaces indoor air in a given space.
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Air GapOpen vertical gap or empty space that separates drinking water supply to be p...
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Air Handling UnitEquipment that includes a fan or blower, heating and/or cooling coils, regula...
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Air MassA large volume of air with certain meteorological or polluted characteristics...
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Air PaddingPumping dry air into a container to assist with the withdrawal of liquid or t...
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Air PermeabilityPermeability of soil with respect to air. Important to the design of soil-gas...
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Air PlenumAny space used to convey air in a building, furnace, or structure. The space ...
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Air PollutantAny substance in air that could, in high enough concentration, harm man, othe...
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Air PollutionThe presence of contaminants or pollutant substances in the air that interfer...
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Air Pollution Control DeviceMechanism or equipment that cleans emissions generated by a source (e.g. an i...
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Air Pollution EpisodeA period of abnormally high concentration of air pollutants, often due to low...
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Air Quality CriteriaThe levels of pollution and lengths of exposure above which adverse health an...
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Air Quality StandardsThe level of pollutants prescribed by regulations that are not be exceeded du...
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Air SpargingInjecting air or oxygen into an aquifer to strip or flush volatile contaminan...
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Air StrippingA treatment system that removes volatile organic compounds (VOCs) from contam...
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Air ToxicsAny air pollutant for which a national ambient air quality standard (NAAQS) d...
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Airborne ParticulatesTotal suspended particulate matter found in the atmosphere as solid particles...
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Airborne ReleaseRelease of any pollutant into the air.
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AlachlorA herbicide, marketed under the trade name Lasso, used mainly to control weed...
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AlarTrade name for daminozide, a pesticide that makes apples redder, firmer, and ...
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AldicarbAn insecticide sold under the trade name Temik. It is made from ethyl isocyan...
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AlgaeSimple rootless plants that grow in sunlit waters in proportion to the amount...
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Algal BloomsSudden spurts of algal growth, which can affect water quality adversely and i...
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AlgicideSubstance or chemical used specifically to kill or control algae.
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AliquotA measured portion of a sample taken for analysis. One or more aliquots make ...
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AlkalineThe condition of water or soil which contains a sufficient amount of alkali s...
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AlkalinityThe capacity of bases to neutralize acids. An example is lime added to lakes ...
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AllergenA substance that causes an allergic reaction in individuals sensitive to it.
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AlluvialRelating to and/or sand deposited by flowing water.
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Alternate MethodAny method of sampling and analyzing for an air or water pollutant that is no...
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Alternative ComplianceA policy that allows facilities to choose among methods for achieving emissio...
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Alternative FuelsSubstitutes for traditional liquid, oil-derived motor vehicle fuels like gaso...
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Alternative Remedial Contract Strategy ContractorsGovernment contractors who provide project management and technical services ...
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Ambient AirAny unconfined portion of the atmosphere
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Ambient MeasurementA measurement of the concentration of a substance or pollutant within the imm...
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Ambient MediumMaterial surrounding or contacting an organism (e.g. outdoor air, indoor air,...
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Ambient TemperatureTemperature of the surrounding air or other medium.
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Amprometric TitrationA way of measuring concentrations of certain substances in water using an ele...
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AnaerobicA life or process that occurs in, or is not destroyed by, the absence of oxygen.
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Anaerobic DecompositionReduction of the net energy level and change in chemical composition of organ...
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AnalyteA compound or property that is to be determined and/or analyzed.
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Animal DanderTiny scales of animal skin, a common indoor air pollutant.
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Animal StudiesInvestigations using animals as surrogates for humans with the expectation th...
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AnisotropyIn hydrology, the conditions under which one or more hydraulic properties of ...
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Annular SpaceThe space between two concentric tubes or casings, or between the casing and ...
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AntagonismInterference or inhibition of the effect of one chemical by the action of ano...
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Antarctic Ozone HoleRefers to the seasonal depletion of ozone in the upper atmosphere above a lar...
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Anti-Degradation ClausePart of federal air quality and water quality requirements prohibiting deteri...
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Anti-MicrobialAn agent that kills microbes.
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Applicable or Relevant and Appropriate Requirements ARARsAny state or federal statute that pertains to protection of human life and th...
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Applied DoseIn exposure assessment, the amount of a substance in contact with the primary...
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AqueousSomething made up of water.
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Aqueous SolubilityThe maximum concentration of a chemical that will dissolve in pure water at a...
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AquiferAn underground geological formation, or group of formations, containing water...
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Aquifer TestA test to determine hydraulic properties of an aquifer.
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AquitardGeological formation that may contain groundwater but is not capable of trans...
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Architectural CoatingsCoverings such as paint and roof tar that are used on exteriors of buildings.
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Area of ReviewIn the UIC program, the area surrounding an injection well that is reviewed d...
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Area SourceAny source of air pollution that is released over a relatively small area but...
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AromaticsA type of hydrocarbon, such as benzene or toluene, with a specific type of ri...
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ArsenicalsPesticides containing arsenic.
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Artesian Aquifer or WellWater held under pressure in porous rock or soil confined by impermeable geol...
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AsbestosA mineral fiber that can pollute air or water and cause cancer or asbestosis ...
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Asbestos AbatementProcedures to control fiber release from asbestos-containing materials in a b...
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Asbestos AssessmentIn the asbestos-in-schools program, the evaluation of the physical condition ...
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Asbestos Program ManagerA building owner or designated representative who supervises all aspects of t...
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Asbestos-Containing Waste Materials ACWMMill tailings or any waste that contains commercial asbestos and is generated...
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AsbestosisA disease associated with inhalation of asbestos fibers. The disease makes br...
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AshThe mineral content of a product remaining after complete combustion.
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AssayA test for a specific chemical, microbe, or effect.
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Assessment EndpointIn ecological risk assessment, an explicit expression of the environmental va...
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AssimilationThe ability of a body of water to purify itself of pollutants.
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Assimilative CapacityThe capacity of a natural body of water to receive wastewaters or toxic mater...
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Association of Boards of CertificationAn international organization representing boards which certify the operators...
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Attainment AreaAn area considered to have air quality as good as or better than the national...
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AttenuationThe process by which a compound is reduced in concentration over time, throug...
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AttractantA chemical or agent that lures insects or other pests by stimulating their se...
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AttritionWearing or grinding down of a substance by friction. Dust from such processes...
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Availability SessionInformal meeting at a public location where interested citizens can talk with...
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Available ChlorineA measure of the amount of chlorine available in chlorinated lime, hypochlori...
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Avoided CostThe cost a utility would incur to generate the next increment of electric cap...
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