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Glossary of Energy Terms


Abiotic: Having an absence of life or living organisms.
Accumulating shear: A feller-buncher shearhead that is capable of accumulating and holding 2 or more cut stems.
ACDP: Federal Air Contaminant Discharge Permit. In Oregon, the Department of Environmental Quality issues the ACDP.
ACFM: Actual cubic feet per minute. The actual cubic feet per minute of gas flowing in a process at the temperature and pressure of the process at that point.
Acid hydrolysis: A chemical process in which acid is used to convert cellulose or starch to sugar.
Activated sludge process: A biological wastewater treatment process in which a mixture of waste water and activated sludge is agitated and aerated. The activated sludge is then separated from the treated wastewater by sedimentation and disposed of or returned to the process as needed.
Adaptive management: A continuing process of action-based planning, monitoring, researching, evaluating, and adjusting with the objective of improving implementation and achieving the goals of the selected alternative.
Adaptive management area: Landscape units designated for development and testing of technical and social approaches to achieving desired ecological, economic, and other social objectives.
Aeration basin: A basin where oxygen is supplied by mechanical agitation or pneumatic means to enhance the breakdown of wastes held in suspension.
Aerobic: Life or biological processes that can occur only in the presence of oxygen.
Air Quality Maintenance Area: Specific populated area where air quality is a problem for one or more pollutants.
Alcohol: A general class of hydrocarbons that contain a hydroxyl group (OH). The term "alcohol" is often used interchangeably with the term "ethanol," even though there are many types of alcohol. (See Butanol, Ethanol, Methanol.)
Alkali: A soluble mineral salt.
Alternative: Under the National Environmental Policy Act, a comprehensive management strategy. When a federal agency is considering an action, the agency must develop and analyze a range of alternatives. The alternatives must show a reasonable range of actions, including a "no action" alternative.
Alternative fuel: As defined in the Energy Policy Act of 1992 (EPACT):
  • Methanol, denatured ethanol and other alcohols, separately or in blends of at least 10 percent by volume with gasoline or other fuels
  • Compressed natural gas
  • Liquefied natural gas
  • Liquefied propane gas
  • Hydrogen
  • Coal derived liquid fuels
  • Fuels other than alcohols derived from biological materials
  • Electricity
  • Biodiesel
  • Any other fuel determed to be substantially not petroleum and yielding potential energy securtity benerfits and substantial environmental benefits.
AMA: See Adaptive Management Area.
Ambient air quality: The condition of the air in the surrounding environment.
aMW: See average megawatt.
Anadromous fish: Fish that hatch in freshwater, migrate to the ocean to mature, then return to freshwater to spawn. An example is salmon.
Anaerobic: Life or biological processes that occur in the absence of oxygen.
Anaerobic digestion: A biochemical process by which organic matter is decomposed by bacteria in the absence of oxygen, producing methane and other byproducts.
Anhydrous: A compound that does not contain water. For example, fuel ethanol is referred to as "anhydrous ethanol" because most of the water has been removed.
Animal Unit: (AU) A measurement of herd size used in the dairy industry. One animal unit is equal to 1000 pounds of animals. For example, a 1,200-pound cow equals 1.2 AU.
Attainment area: A geographic region where the concentration of a specific air pollutant does not exceed federal standards.
Average megawatt: (MWa or aMW) One megawatt of capacity produced continuously over a period of one year. 1 aMW = 1 MW x 8760 hours/year = 8,760 MWh = 8,760,000 kWh.
Avoided costs: An investment guideline describing the value of a conservation or generation resource investment by the cost of more expensive resources that a utility would otherwise have to acquire.
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Background level: The average amount of a substance present in the environment. Originally referring to naturally occurring phenomena. Used in toxic substance monitoring.
Backup rate: A utility charge for providing occasional electricity service to replace on-site generation.
Backup electricity, backup services: Power or services needed occasionally; for example, when on-site generation equipment fails.
BACT: See best available control technology.
Baffle chamber: In incinerator design, a chamber designed to settle fly ash and coarse particulate matter by changing the direction and reducing the velocity of the combustion gases.
Baghouse: A chamber containing fabric filter bags that remove particles from furnace stack exhaust gases. Used to eliminate particles greater than 20 microns in diameter.
Bar screen: A screen made of parallel bars set 3/4" to 2" apart used to filter out large objects.
Barrel of oil equivalent: A unit of energy equal to the amount of energy contained in a barrel of crude oil. Approximately 5.78 million Btu or 1,700 kWh. A barrel is a liquid measure equal to 42 gallons.
Baseload capacity: The power output that generating equipment can continuously produce.
Baseload demand: The minimum demand experienced by an electric utility, usually 30-40% of the utility´s peak demand.
BDU: See bone dry unit.
Benzene: A toxic, six-carbon aromatic component of gasoline. A known carcinogen.
Best available control measures: The most effective measures for controlling small or dispersed particulates from sources such as soot and ash from woodstoves and open burning of brush, timber, grasslands, or trash.
Best available control technology: (BACT) That combination of production processes, methods, systems, and techniques that will result in the lowest achievable level of emissions of air pollutants from a given facility. BACT is an emission limitation that the permitting authority determines on a case-by-case basis, taking into account energy, environmental, economic and other costs of control. BACT may include fuel cleaning or treatment or innovative fuel combustion techniques. Applies in attainment areas.
Best management practices: A practice or combination of practices that a designated agency determines to be the most effective, practical means of reducing the amount of pollution generated by nonpoint sources to a level compatible with water quality goals.
Billing credit: In the Pacific Northwest, a payment by the Bonneville Power Administration to a wholesale customer for actions taken by that customer to reduce BPA´s obligations to acquire new resources. The payment is usually made by an offset against billings.
Bioaccumulants: Substances in contaminated air, water, or food that increase in concentration in living organisms exposed to them because the substances are very slowly metabolized or excreted.
Bioaccumulation: See bioconcentration.
Bioassay: A study of a living organism to measure the effect of a substance, factor, or condition.
Biochemical conversion process: The use of living organisms or their products to convert organic material to fuels, chemicals or other products.
Biochemical oxygen demand: (BOD) A standard means of estimating the degree of water pollution, especially of water bodies that receive contamination from sewage and industrial waste. BOD is the amount of oxygen needed by bacteria and other microorganisms to decompose organic matter in water. The greater the BOD, the greater the degree of pollution. Biochemical oxygen demand is a process that occurs over a period of time and is commonly measured for a five-day period, referred to as BOD5.
Bioconcentration: (Bioaccumulation) The accumulation of a chemical in tissues of an organism to levels greater than in the environment in which the organism lives.
Biodegradable: Capable of decomposing rapidly under natural conditions.
Biodiesel: A biofuel produced through transesterification, a process in which organically-derived oils are combined with alcohol (ethanol or methanol) in the presence of a catalyst to form ethyl or methyl ester. The biomass-derived ethyl or methyl esters can be blended with conventional diesel fuel or used as a neat fuel (100% biodiesel). Biodiesel can be made from soybean or rapeseed oils, animal fats, waste vegetable oils or microalgae oils.
Biodiversity: The relative abundance and variety of plant and animal species and ecosystems within particular habitats
Bioenergy: Renewable energy produced from organic matter. The conversion of the complex carbohydrates in organic matter to energy. Organic matter may either be used directly as a fuel or processed into liquids or gases.
Biofuels: Fuels made from biomass. Biofuels include ethanol, biodiesel and methanol.
Biogas: A combustible gas derived from decomposing biological waste. Biogas normally consists of 50 to 60 percent methane.
Biological assessment: A specific process required as part of an environmental assessment. An evaluation of potential effects of a proposed project on proposed, endangered, threatened and sensitive animal and plant species and their habitats.
Biological magnification: The process by which substances such as pesticides or heavy metals become concentrated as they move up the food chain.
Biological oxidation: Decomposition of organic materials by microorganisms.
Biomass: Renewable organic matter such as agricultural crops and residue, wood and wood waste, animal waste, aquatic plants and organic components of municipal and industrial wastes.
Biomass fuel: Liquid, solid or gaseous fuel produced by conversion of biomass.
Biomass energy: See bioenergy.
Biome: The community of living organisms in a given area.
Bioremediation: The use of living organisms to clean up pollutants from soil or water.
Biosphere: The portion of the Earth and its atmosphere that can support life.
Biota: The animal and plant life of a region or period.
Biotechnology: Technology that use living organisms to produce products such as medicines, to improve plants or animals, or to produce microorganisms for bioremediation.
Biotic: Pertaining to life or living organisms.
Biotic community: A naturally occurring, interdependent community of plants and animals that live in the same environment.
Block: A repetition/replication of the Early, Mid and Late Seral Treatment plots and a Control plot. See Repetition/replication.
BMP: See best management practices.
Board feet: (BF) Unit of measure for logs and lumber. One board foot is equivalent to a piece of wood 1 inch thick, 12 inches wide, and 12 inches long.
BOD: See biochemical oxygen demand.
BOD5: The amount of dissolved oxygen consumed in five days by biological processes breaking down organic matter. See biochemical oxygen demand.
Boiler horsepower: A measure of the maximum rate of heat energy output of a steam generator. One boiler horsepower equals 33,480 Btu/hr output in steam.
Boiler: Any device used to burn biomass fuel to heat water for generating steam.
Bone dry: Having zero percent moisture content. Wood heated in an oven at a constant temperature of 212 degrees F or above until its weight stabilizes is considered bone dry or oven dry.
Bone dry ton: (or "oven dry ton"). An amount of wood that weighs 2,000 pounds at zero percent moisture content.
Bone dry unit: (BDU) A quantity of wood residue which weighs 2,400 pounds at zero percent moisture content.
Bottom ash: Noncombustible ash that is left after solid fuel has been burned.
Bottoming cycle: A cogeneration system in which steam is used first for process heat and then for electric power production.
British thermal unit: (Btu) A unit of heat energy equal to the heat needed to raise the temperature of one pound of water one degree Fahrenheit at one atmosphere pressure (sea level).
Broadcast burn: Controlled fire over the entire surface of a designated area.
Bryophytes: Plants of the phylum Bryophyta, including mosses, liverworts and hornworts, characterized by the lack of true roots, stems and leaves.
Btu: See British thermal unit
Buck: To cut a log into smaller portions.
Bulk density: Weight per unit of volume, usually specified in pounds per cubic foot.
Butane: A gas derived from natural gas. Used as a component of gasoline. Used in liquefied petroleum gas (LPG) for domestic and industrial applications.
Butanol or butyl alcohol: An alcohol with the chemical formula CH3(CH2)3OH. It is formed during anaerobic fermentation using bacteria to convert the sugars to butanol and carbon dioxide.
Butt log: The log taken from the base of a tree; often slightly irregular.
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C unit: (CCF) One hundred cubic feet of solid wood. Used as a log measure or as a measure of solid wood content. 1 CCF contains typically 1.4 BDT.
Cable yarding: A term used to describe a means of removing logs from the stump area to a landing or yarding area through use of an overhead system of winch-driven cables to which logs are attached with cables.
Candidate species: See threatened, endangered and sensitive species.
Capacity: The maximum power that a machine or system can produce or carry safely. The maximum instantaneous output of a resource under specified conditions. The capacity of generating equipment is generally expressed in kilowatts or megawatts.
Capacity factor: The amount of energy that a power plant actually generates compared to its maxumum rated output, expressed as a percentage.
Capital cost: The total investment needed to complete a project and bring it to a commercially operable status. The cost of construction of a new plant. The expenditures for the purchase or acquisition of existing facilities.
Carbohydrate: A chemical compound made up of carbon, hydrogen, and oxygen. Includes sugars, cellulose, and starches.
Carbon Dioxide: (CO2) A product of combustion. The most common greenhouse gas.
Carbon Monoxide: (CO) A colorless, odorless gas produced by incomplete combustion. Carbon monoxide is poisonous if inhaled.
Carbon Sequestration: The absorption and storage of carbon dioxide from the atmosphere. Naturally-occurring in plants.
Cascade aeration: Aeration of an effluent stream through the action of falling water.
Cellulase: Enzymes that act to degrade cellulose. Cellulases are produced commonly by fungal and microbial organisms.
Cellulose: The main carbohydrate in living plants. Cellulose forms the skeletal structure of the plant cell wall.
Centralized sewage treatment: The collection and treatment of sewage from many sources to remove pollutants and pathogens.
CEQ: See Council on Environmental Quality.
Cetane: Ignition performance rating of diesel fuel.
cfm: Cubic feet per minute.
Char: The remains of solid biomass that has been incompletely combusted, such as charcoal if wood is incompletely burned.
Chemical oxygen demand: (COD) The amount of dissolved oxygen required to combine with chemicals in wastewater. A measure of the oxygen equivalent of that portion of organic matter that is susceptible to oxidation by a strong chemical oxidizing agent.
Chip vans: Special construction bottom dump trucks (grain trucks) or conventional tractor- trailer vans used for hauling pulp chips, mill residues, hog fuel, and other biomass of smaller piece sizes.
Chipper: A machine that produces wood chips by knife action.
Chips: Woody material cut into short, thin wafers. Chips are used as a raw material for pulping and fiberboard or as biomass fuel.
Chlorofluorocarbon: A family of chemicals composed primarily of carbon, hydrogen, chlorine, and fluorine. Used principally as refrigerants and industrial cleansers. Chlorofluorocarbons have the tendency to destroy the Earth´s protective ozone layer.
Choker: A cable loop that is attached to a log during the yarding process.
CHU: See Critical habitat unit.
Clarifier: A tank used to remove solids by gravity, to remove colloidal solids by coagulation, and to remove floating oil and scum through skimming.
Class I area: Any area designated for the most stringent protection from air quality degradation.
Class II area: Any area where air is cleaner than required by federal air quality standards and designated for a moderate degree of protection from air quality degradation. Moderate increases in new pollution may be permitted in Class II areas.
Clean Air Act: (CAA) National law establishing ambient air quality emission standards to be implemented by participating states. Originally enacted in 1963, the CAA has been amended several times, most recently in 1990. The CAA includes vehicle emission standards regulating the emission of criteria pollutants (lead, ozone, carbon monoxide, sulfur dioxide, nitrogen oxides and particulate matter). The 1990 amendments added reformulated gasoline (RFG) requirements and oxygenated gasoline provisions.
Clearcut: The removal, in a single cutting, of the entire stand of trees within a designated area. Stand regeneration is accomplished by planting the site or by natural seeding from adjacent stands.
Clone: A genetically identical duplicate of an organism.
Coastal Zone Management Act: National law encouraging states to develop coastal management programs. The act establishes a method for the federal government to approve states´ plans, establishes funding for approved plans, and requires federal actions to be consistent with states´ plans.
COD: See chemical oxygen demand.
Code of Federal Regulations: (CFR) Federal regulations published by the Office of the Federal Registrar, National Archives, and Records Service of the General Services Administration.
Cogeneration: The sequential production of electricity and useful thermal energy from a common fuel source. Rejected heat from industrial processes can be used to power an electric generator (bottoming cycle). Conversely, surplus heat from an electric generating plant can be used for industrial processes, or space and water heating purposes (topping cycle).
Coliform bacteria: Bacteria whose presence in waste water is an indicator of pollution and of potentially dangerous contamination.
Combined cycle: Two or more generation processes in series or in parallel, configured to optimize the energy output of the system.
Combined-cycle power plant: The combination of a gas turbine and a steam turbine in an electric generation plant. The waste heat from the gas turbine provides the heat energy for the steam turbine.
Combined heat and power: (CHP) See cogeneration. The term is more commonly used in Europe and other foreign countries.
Combustion: Burning. The transformation of biomass fuel into heat, chemicals, and gases through chemical combination of hydrogen and carbon in the fuel with oxygen in the air.
Combustion gases: The gases released from a combustion process.
Combustion air: The air fed to a fire to provide oxygen for combustion of fuel. It may be preheated before injection into a furnace.
Combustion efficiency: The actual heat produced by combustion divided by the total heat potential of the fuel consumed.
Combustion turbine: See gas turbine.
Commercial forest land: Forested 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 production by statute or administrative regulation.
Compressed natural gas: (CNG) Natural gas that has been compressed under high pressure (typically 2000 to 3600 psi).
Condenser: A heat-transfer device that reduces a fluid from a vapor phase to a liquid phase.
Condensing, controlled extraction turbines: A controlled turbine that bleeds off (condenses) part of the main stream flow at one (single extraction) or two (double extraction) points. Used when process steam is required at pressures below the inlet pressure and above the exhaust pressure.
Condensing turbine: A turbine used for electrical power generation from a minimum amount of steam. To increase plant efficiency, these units can have multiple uncontrolled extraction openings for feed-water heating.
Condensing power: Power 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.
Conditional use permit: A permit, with conditions, allowing an approved use on a site outside the appropriate zoning class.
Conservation: Efficiency of energy use, production, transmission, or distribution that results in a decrease of energy consumption while providing the same level of service.
Control plot: A 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 and Late Seral).
Conventional forest products: Any commercial roundwood product (boards, dimension lumber, pulp and paper products) except fuelwood.
Conversion efficiency: A comparison of the useful energy output to the potential energy contained in the fuel. The efficiency calculation relates to the form of energy produced. A direct comparison of the efficiency of different conversion processes can be made only when the processes produce the same form of energy output.
Conveyor: A mechanical apparatus for carrying bulk material from place to place; for example, an endless moving belt or a chain of receptacles.
Coppice regeneration: The ability of certain hardwood species to regenerate by producing multiple new shoots from a stump left after harvest.
Cord: A 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 1.2 bone dry tons.
Corn stover: Residue materials from harvesting corn consisting of the cob, leaves and stalk.
Corporate average fuel economy: (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 for its car or truck fleet.
Council on Environmental Quality: (CEQ) An advisory council to the President established by the National Environmental Policy Act of 1969. The CEQ reviews federal programs for their effect on the environment, conducts environmental studies, and advises the President on environmental matters.
Critical habitat: 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 those physical and biological features essential to the conservation of the species, and that may require special management considerations or protection; and specific areas outside the geographic area occupied by a species at the time it is listed, upon determination that such areas are essential for the conservation of the species."
Crop tree: Usually a conifer tree grown to provide wood products.
Cull section: A log cut from a tree that is rejected because of defects making it unsuitable for conventional forest products.
Cull trees: Live saw-timber and pole-timber size trees which do not contain a merchantable sawlog due to poor form, quality, or undesirable species.
Cull: Any item of production picked out for rejection because it does not meet certain specifications. Chip culls and utility culls are specifically defined for purposes of log grading by percentage of sound wood content.
Cumulative effects: Effects on the environment resulting from actions that are individually minor but that add up to a greater total effect as they take place over a period of time.
Cyclone separator: A device used to remove particulate matter suspended in exhaust gases.
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DBH: See diameter at breast height.
Deaeration: Removal of gases from a liquid.
Decibels: (dBA) A scale to measure sound levels.
Decision notice: The written record of a federal agency decision after an environmental assessment. The decision notice chooses one of the alternatives, or a blend of the alternatives. A decision notice is subject to appeal.
Decoupling: A regulatory design that breaks the link between utility revenues and energy sales to encourage utility investment in conservation.
DEIS: See draft environmental impact statement.
Denatured: Ethanol that has had a substance added to make it unfit for human consumption.
Densification: A mechanical process to compress biomass (usually wood waste) into pellets, briquettes, cubes, or densified logs.
DEQ: Oregon Department of Environmental Quality.
Desired future condition: A vision of the desired future state of a specific area. A description of land and resource conditions expected to result if management goals and objectives are achieved.
Diameter at breast height: (DBH) The diameter of a tree measured 4 feet 6 inches above the ground.
Diesel engine: A compression-ignition piston engine in which fuel is ignited by injecting it into air that has been heated (unlike a spark-ignition engine).
Digester: An airtight vessel or enclosure in which bacteria decomposes biomass in water to produce biogas.
Dioxin: A family of compounds, some of which are hazardous, that result from combustion of carbon materials. The most toxic of these compounds is 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin.
Discount rate: A rate used to convert future costs or benefits to their present value.
Discounting: A method of converting future dollars into present values, accounting for interest costs or forgone investment income. Used to convert a future payment into a value that is equivalent to a payment now.
Dispersal habitat: See spotted owl habitat.
Distillate oil: Any distilled product of crude oil. A light petroleum product used for home heating and most machinery.
Distillation: The process to separate the components of a liquid mixture by boiling the liquid and then recondensing the resulting vapor.
Distillers´ dried grains: (DDG) The dried byproduct of the grain fermentation process. Typically used as a high-protein animal feed.
Distribution: The transfer of electricity from the transmission network to the consumer.
District heating or cooling: A system that involves the central production of hot water, steam, or chilled water and the distribution of these transfer media to heat or cool buildings.
Diversity: The distribution and abundance of different plants and animals within an area.
Downdraft gasifier: A gasifier in which the product gases pass through a combustion zone at the bottom of the gasifier.
Draft environmental impact statement: (DEIS) A draft statement of environmental effects. Section 102 of the National Environmental Policy Act requires a DEIS for all major federal actions. The DEIS is released to the public and other agencies for comment and review.
Drainage: See Watershed.
Dry Ton: 2,000 pounds of material dried to a constant weight.
Duff: The layer of forest litter.
Dutch oven furnace: One of the earliest types of furnaces, having a large, rectangular box lined with firebrick (refractory) on the sides and top. Commonly used for burning wood. Heat is stored in the refractory and radiated to a conical fuel pile in the center of the furnace.
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E85: A blend of 15 percent gasoline and 85 percent denatured ethanol by volume.
Early seral species: Shrubs (such as ceanothus) and hardwoods (usually in tree form, such as red alder, bitter cherry and big leaf maple) that start growing in natural succession soon after a disturbance (fire or logging).
Ecology: The study of the interrelationships between organisms and their environment. From the Greek word oikos, meaning "house."
Economic sector: A subdivision of economic activities based on major purpose (for example, "commercial sector" or "private sector").
Ecosystem: The system of interactions between living organisms and their environment.
Effluent: The treated waste water discharged by sewage treatment plants.
EFSC: See Energy Facility Siting Council.
EIS: See environmental impact statement.
Electrical horsepower: See horsepower.
Electricity: Electric current used as a power source.
Emission offset: A reduction in the air pollution emissions of existing sources to compensate for emissions from new sources.
Emissions: Waste substances released into the air or water.
Endangered species: See threatened, endangered, and sensitive species.
Endemic: Naturally existing at low levels in the environment.
Energy: The ability to do work.
Energy crops: Crops grown specifically for their fuel value. These include food crops such as corn and sugarcane and nonfood crops such as poplar trees and switchgrass. Currently, two energy crops are under development in the United States: short-rotation woody crops, which are fast-growing hardwood trees harvested in 5 to 8 years, and herbaceous energy crops, such as perennial grasses, which are harvested annually after taking 2 to 3 years to reach full productivity.
Energy Facility Siting Council: (EFSC) In Oregon, a seven-member council that coordinates and approves siting for most large power plants, transmission lines and pipelines.
Environment: The external conditions that affect organisms and influence their development and survival.
Environmental assessment: (EA) A public document that analyzes a proposed federal action for the possibility of significant environmental impacts. The analysis is required by the National Environmental Policy Act. If the environmental impacts will be significant, the federal agency must then prepare an environmental impact statement.
Environmental impact statement: (EIS) A statement of the environmental effects of a proposed action and of alternative actions. Section 102 of the National Environmental Policy Act requires an EIS for all major federal actions.
Enzymatic hydrolysis: A process by which enzymes (biological catalysts) are used to break down starch or cellulose into sugar.
EP Toxicity: A test defined by the federal Environmental Protection Agency to check a substance for the presence of arsenic, barium, cadmium, chromium, lead, mercury, selenium, or silver. 40 CFR 261.24 defines the concentrations constituting hazardous waste and the test procedure.
Ethanol: Ethyl alcohol produced by fermentation and distillation. An alcohol compound with the chemical formula CH3CH20H formed during sugar fermentation by yeast. Grain alcohol.
Ethyl tertiary butyl ether: (ETBE) An ether similar to MTBE. ETBE is manufactured by reacting ethanol with isobutylene. ETBE has high octane and low volatility characteristics. Used as an oxygenate.
Evapotranspiration: The water released from plants as they grow. The evaporation of water from plant surfaces and adjacent soil.
Excess annual growth: The amount by which new forest growth exceeds removal in a year. The annual quantity of wood produced in a forest in excess of market demand.
Externality: A cost or benefit not accounted for in the price of goods or services. Often "externality" refers to the cost of pollution and other environmental impacts.
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Facultative ponds: Ponds having an aerobic zone on the top and an anaerobic zone on the bottom.
Fast pyrolysis: Thermal conversion of biomass by rapid heating to between 450ø to 600øC in the absence of oxygen.
Federal Water Pollution Control Act: A federal regulatory law administered by the states. The act created the National Pollution Discharge Elimination System.
Feedstock: Any material that can be converted to another form of fuel or energy product.
FEIS: Final environmental impact statement.
Fell: To cut down a tree. Cutting down trees and sawing them to manageable lengths is referred to as "felling and bucking" or "falling and bucking."
Feller-buncher: A self-propelled machine that cuts trees with giant shears near ground level and then stacks the trees into piles to await skidding.
Fermentation: The biological conversion of biomass by yeast or sugar. The products of fermentation are carbon dioxide and alcohol.
Finding of No Significant Impact: (FONSI) A document describing the reasons why the impacts of a proposed federal action are not significant. Required by the National Environmental Policy Act after an environmental assessment when a federal agency is not preparing an environmental impact statement.
Fine: A very small particle of material such as very fine sander dust or very small pieces of bark.
Firm power: (firm energy) Power which is guaranteed by the supplier to be available at all times during a period covered by a commitment. That portion of a customer´s energy load for which service is assured by the utility provider.
Fischer-Tropsch Fuels: Liquid hydrocarbon fuels produced by a process that combines carbon monoxide and hydrogen. The process is used to convert coal, natural gas and low-value refinery products into a high-value diesel substitute fuel.
Flexible-fuel vehicle: A vehicle with a single fuel tank designed to run on varying blends of unleaded gasoline with either ethanol or methanol.
Floodplain: Relatively flat surfaces adjacent to active stream or river channels, formed by deposition of sediments during major floods. The floodplain may be covered by water during floods:
  • 100-year floodplain: That area that would be covered by water during the 100-year flood event.
  • Historic floodplain: An area larger than the 100-year floodplain.
Flow rate: The amount of water that moves through an area (usually pipe) in a given period of time.
Fluidized-bed boiler: A large, refractory-lined vessel with an air distribution member or plate in the bottom, a hot gas outlet in or near the top, and some provisions for introducing fuel. The fluidized bed is formed by blowing air up through a layer of inert particles (such as sand or limestone) at a rate that causes the particles to go into suspension and continuous motion. The super-hot bed material increased combustion efficiency by its direct contact with the fuel.
Fly ash: Small ash particles carried in suspension in combustion products.
FONSI: See Finding of No Significant Impact.
Foraging habitat: See Spotted owl habitat.
Forest Plan: The document that sets goals, objectives, desired future condition, standards and guidelines, and overall programmatic direction for a National Forest. Required by the National Forest Management Act of 1976.
Forest residues: Material not harvested or removed from logging sites in commercial hardwood and softwood stands as well as material resulting from forest management operations such as precommercial thinnings and removal of dead and dying trees.
Forest health: A condition of ecosystem sustainability and attainment of management objectives for a given forest area. Usually considered to include green trees, snags, resilient stands growing at a moderate rate and endemic levels of insects and disease. Natural processes still function or are duplicated through management intervention. A more fire-tolerant forest condition and the elimination of unnatural woody biomass accumulations that have resulted from past fire suppression.
Forested areas or land: Any land that is capable of producing or has produced forest growth or, if lacking forest growth, has evidence of a former forest and is not now in other use.
Forwarder: A self-propelled vehicle to transport harvested material from the stump area to the landing. Trees, logs, or bolts are carried off the ground on a stake-bunk, or are held by hydraulic jaws of a clam-bunk. Chips are hauled in a dumpable or open-top bin or chip-box.
Fossil fuel: Solid, liquid or gaseous fuels formed in the ground after millions of years by chemical and physical changes in plant and animal residues under high temperature and pressure. Oil, natural gas and coal are fossil fuels.
Francis turbine: A water-powered turbine used to transform water falling vertically to mechanical (rotating) energy.
Fuel: Any material that can be converted to energy.
Fuel cell: A device that converts the chemical energy of a fuel directly to electricity and heat, without combustion.
Fuel-cell furnace: A variation of the Dutch oven design, that usually incorporates a primary and secondary combustion chamber (cell). The primary chamber is a vertical refractory-lined cylinder with a grate at the bottom in which combustion is partially completed. Combustion is completed in the secondary chamber.
Fuel cycle: The series of steps required to produce electricity. The fuel cycle includes mining or otherwise acquiring the raw fuel source, processing and cleaning the fuel, transport, electricity generation, waste management and plant decommissioning.
Fuel handling system: A system for unloading wood fuel from vans or trucks, transporting the fuel to a storage pile or bin, and conveying the fuel from storage to the boiler or other energy conversion equipment.
Furnace: An enclosed chamber or container used to burn biomass in a controlled manner to produce heat for space or process heating.
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Gas engine: A piston engine that uses gaseous fuel rather than gasoline. Fuel and air are mixed before they enter cylinders; ignition occurs with a spark.
Gas shift process: A process in which carbon monoxide and hydrogen react in the presence of a catalyst to form methane and water.
Gas turbine: (combustion turbine) A turbine that converts the energy of hot compressed gases (produced by burning fuel in compressed air) into mechanical power. Often fired by natural gas or fuel oil.
Gasification: A chemical or heat process to convert a solid fuel to a gaseous form.
Gasifier: A device for converting solid fuel into gaseous fuel. In biomass systems, the process is also referred to as pyrolitic distillation. See pyrolysis.
Gasohol: A motor vehicle fuel which is a blend of 90 percent  unleaded gasoline with 10 percent ethanol (by volume). This term was used in the late 1970s.
Generator: A machine used for converting rotating mechanical energy to electrical energy.
Geomorphic: Pertaining to those processes that affect the form or shape of the surface of the earth.
Geothermal energy: Energy derived from the natural heat of the Earth contained in hot rocks, hot water, hot brines or steam.
Girdling: Killing a tree by removing a strip of bark from around its trunk.
gr/SCF: Grains of pollutant per standard cubic foot of gas. A measure of dust particles in a gas stream.
Green ton: 2,000 pounds of undried biomass material. Moisture content must be specified if green tons are used as a measure of fuel energy.
Green logging: The logging of timber that is still alive.
Greenhouse effect: A warming of the Earth and its atmosphere caused by greenhouse gases and water vapor trapping heat from the sun.
Greenhouse gases: Gases that trap the heat of the sun in the Earth´s atmosphere, producing the greenhouse effect. The two major greenhouse gases are water vapor and carbon dioxide. Other greenhouse gases include methane, ozone, chlorofluorocarbons, and nitrous oxide.
Grid: An electric utility´s system for distributing power.
Grid connection: Joining a plant that generates electric power to a utility system so that electricity can flow in either direction between the utility system and the plant.
Gross heating value: (GHV) The maximum potential energy in the fuel as received, considering moisture content (MC). It reflects the heat used to evaporate moisture. Compare higher heating value (HHV). Expressed as:
GHV = HHV ((1 - MC) / 100)
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Habitat: The area where a plant or animal lives and grows under natural conditions. Habitat includes living and non-living attributes and provides all requirements for food and shelter.
Hammermill: A device consisting of a rotating head with free-swinging hammers which reduce chips or hogged fuel to a predetermined particle size through a perforated screen.
Hand pile: A pile of slash constructed by a crew, not by machine. Hand piles are typically less than 10´ high and less than 12´ in diameter.
Hardwoods: Usually broad-leaved and deciduous trees.
Head: The vertical distance water drops from the highest level to the level of the receiving body of water.
Header: A pipe from which two or more tributary pipes run.
Heat rate: The amount of fuel energy required by a power plant to produce one kilowatt-hour of electrical output. A measure of generating station thermal efficiency, generally expressed in Btu per net kWh. It is computed by dividing the total Btu content of fuel burned for electric generation by the resulting net kWh generation.
Heat transfer efficiency: The useful heat output released to a room divided by the actual heat produced in the firebox.
Heating value: The maximum amount of energy that is available from burning a substance.
Hectare: An area equal to 2.47 acres. There are 100 hectares in 1 square kilometer.
Herbicide: A chemical used to kill unwanted vegetation.
Heterogeneity: The condition or state of being different in kind or nature.
HHV: See higher heating value.
Hibernacula: Caves or other structures used by bats for hibernation.
Higher heating value: (HHV) The maximum potential energy in dry fuel. For wood, the range is 7,600 to 9,600 Btu/lb.
Hog fuel or hogged fuel: Wood residues processed through a chipper or mill to produce coarse chips normally used for fuel. Bark, sawdust, planer shavings, wood chunks, dirt, and fines may be included.
Horsepower: (electrical horsepower; hp) A unit for measuring the rate of mechanical energy output. The term is usually applied to engines or electric motors to describe maximum output. 1 hp = 745.7 Watts = 0.746 kW = 2,545 Btu/hr.
hp: See horsepower.
Hybrid electric vehicle: A vehicle that is powered by two or more energy sources, one of which is electricity.
Hydraulic load: Amount of liquid going into a system.
Hydrocarbon: Any chemical compound containing hydrogen, oxygen, and carbon.
Hydroelectric power: The generation of electricity using falling water.
Hydrolysis: A process of breaking chemical bonds of a compound by adding water to the bonds.
Hypothesis: A proposition tentatively assumed. Science tests the logical consequences of a hypothesis against facts that are known or that may be determined.
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Imhoff treatment system: In wastewater treatment, a tank without aeration or oxygenation where solids settle out. The solids are digested in a separate compartment in the bottom.
Incinerator: Any device used to burn solid or liquid residues or wastes as a method of disposal. In some incinerators, provisions are made for recovering the heat produced.
Inclined grate: A type of furnace in which fuel enters at the top part of a grate in a continuous ribbon, passes over the upper drying section where moisture is removed, and descends into the lower burning section. Ash is removed at the lower part of the grate.
Incremental energy costs: The cost of producing and transporting the next available unit of electrical energy. Short run incremental costs (SRIC) include only incremental operating costs. Long run incremental costs (LRIC) include the capital cost of new resources or capital equipment.
Independent power producer: A power production facility that is not part of a regulated utility.
Indirect liquefaction: Conversion of biomass to a liquid fuel through a synthesis gas intermediate step.
Induction generator: A variable speed multi-pole electric generator.
Infiltration: Leakage of ground water into a sewage collection system.
Inflow: Water (and pollutants) that enter sewage systems through street inlets, roof drains, and similar sources.
Influent: Wastewater going into the sewage treatment plant.
Inorganic compounds: Those compounds lacking carbon but including carbonates and cyanides. Compounds not having the organized anatomical structure of animal or vegetable life.
Integrated resource planning: See least cost planning.
Intensive management: Planned, active treatment to improve the quality and quantity of timber within a stand. A general term that distinguishes active forest management from passive forest management.
Interconnection: A connection or link between power systems that enables them to draw on one another´s reserve in time of need.
Interruptible load: Loads that can be curtailed at the supplier´s discretion or in accordance with a contractual agreement.
Investment tax credit: A specified percentage of the dollar amount of certain new investments that a company can deduct as a credit against its income tax bill.
Investor-owned utility: (IOU) A private power company owned by and responsible to its shareholders. The Public Utility Commission regulates IOUs in Oregon.
Issues: Unresolved conflicts regarding alternative uses of available resources. Subjects of public interest.
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No terms begin with "J ."
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Kilowatt: (kW) A measure of electrical power equal to 1,000 Watts. 1 kW = 3,413 Btu/hr = 1.341 horsepower.
Kilowatt hour: (kWh) A measure of energy equivalent to the expenditure of one kilowatt for one hour. For example, 1 kWh will light a 100-watt light bulb for 10 hours. 1 kWh = 3,413 Btu.
Knutson-Vandenberg Act: (KV) Federal law that allows the U.S. Forest Service to collect money from a timber sale for resource enhancement, protection, and improvement work in the timber sale vicinity.
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LAER: See lowest achievable emission rate.
Land Use Board of Appeals: (LUBA) In Oregon, a seven-member board appointed to adjudicate land use disputes.
Land Conservation and Development Commission: (LCDC) In Oregon, a commission appointed to determine land use policy.
Landfill gas: Gas that is generated by decomposition of organic material at landfill disposal sites. Landfill gas is approximately 50 percent methane.
Landing: A cleared working area on or near a timber harvest site at which processing steps are carried out.
Landscape: A region consisting of interacting ecosystems determined by geology, soils, climate, biota, and human influences. A landscape is made up of watersheds and smaller ecosystems.
Large woody debris: Dead woody material greater than 20" in diameter on the ground or in a stream or river. It may consist of logs, trees, or parts of trees. Large woody debris contributes to long-term site productivity and health in several ways. It supplies nutrients to the soil, supports symbiotic fungi that are beneficial to conifers, and provides habitat for beneficial rodents and insects.
Late seral species: Shade tolerant species, primarily vine maple shrubs and western red cedar and western hemlock trees. These species follow the mid seral species in natural succession.
Late-successional forest: Forest seral stages which include mature and old- growth age classes.
Late-successional reserve: An area of forest where the management objective is to protect and enhance conditions of late successional and old-growth forest ecosystems.
Late seral treatment: A treatment in which late seral species will be established after thinning.
LCDC: See Land Conservation and Development Commission.
Leachates: Liquids percolated through waste piles. Leachate can include various minerals, organic matter, or other contaminants and can contaminate surface water or ground water.
Least cost planning: (integrated resource planning) A method of power planning that recognizes load uncertainty, embodies an emphasis on risk management, and reviews all available and reliable resources to meet future loads. It takes into consideration all costs of a resource, including capital, labor, fuel, maintenance, decommissioning, known environmental impacts, and the difficulty in quantifying the consequences of selecting one resource over another. Least cost planning seeks to minimize total energy costs.
Levelized life-cycle cost: The present value of the cost of a resource, including capital, financing and operating costs, expressed as a stream of equal annual payments. This stream of payments can be converted to a unit cost of energy by dividing the annual payment amount by the annual kilowatt-hours produced or saved. By levelizing costs, resources with different lifetimes and generating capabilities can be compared.
LH2O: The heat (Btu) needed to vaporize and superheat one pound of water.
Life-cycle costing: A method of comparing costs of equipment or buildings based on original costs plus all operating and maintenance costs over the useful life of the equipment. Future costs are discounted.
Lignin: An amorphous polymer that, together with cellulose, forms the cell walls of woody plants. Lignin acts as the bonding agent between cells.
Liquefaction: The process of converting biomass from a solid to a liquid. The conversion process is a chemical change that takes place at elevated temperatures and pressures.
Liquid hydrocarbon: One of a very large group of chemical compounds composed only of carbon and hydrogen. The largest source of hydrocarbons is petroleum.
Liquefied natural gas: (LNG) Natural gas that has been condensed to a liquid by cooling the gas.
Live bottom: A material storage bin or truck with a floor which incorporates a device for removing or unloading the material contained in the bin.
Load factor: Load factor is the ratio of average demand to maximum demand or to capacity.
Load: (1) The amount of electrical power required at a given point on a system. (2) The average demand on electrical equipment or on an electric system.
Load management: Any method or device that evens out electric power demand by eliminating uses during peak periods or shifting usage from peak time to off-peak time.
Log choker: A length of cable or chain that is wrapped around a log or harvested tree to secure the log to the winch cable of a skidder or to an overhead cable yarding line.
Logging residues: The unused portion of wood and bark left on the ground after harvesting merchantable wood. The material may include tops, broken pieces, and unmerchantable species.
Long-term productivity: The capacity of a site to support forest ecosystems over generations of humans and trees as measured against some defined reference.
Long ton: (shipping ton) 2,240 pounds. Commonly used in Great Britain.
Lower heating value: (LHV) The potential energy in a fuel if the water vapor from combustion of hydrogen is not condensed.
Lowest achievable emissions rate: (LAER) Used to describe air emissions control technology. A rate of emissions defined by the permitting agency. LEAR sets emission limits for non-attainment areas.
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Major source: A source that emits, or has the potential to emit, a pollutant regulated under the Clean Air Act in excess of a specified rate in a nonattainment area.
Management plan: A plan guiding overall management of an area administered by a federal or state agency. A management plan usually includes objectives, goals, standards and guidelines, management actions, and monitoring plans.
Management activities: Planned activities initiated by land managers to meet the desired future condition for an area. Management activities may include thinning, timber harvest, prescribed burning, tree planting, and other activities.
Management area: Management areas are specific geographical areas defined by a forest plan. Each management area has a set of objectives and a management prescription unique to it.
Management indicator species: Species selected as ecological indicators. The welfare of a management indicator species is presumed to be an indicator of the welfare of other species using the same habitat. The condition and welfare of these species can be used to assess the impacts of management actions on particular areas or habitats.
Mass burn facility: A facility in which the pretreatment of MSW includes only inspection and simple separation to remove oversize, hazardous, or explosive materials. Large mass burn facilities have capacities of 3000 tons of MSW per day or more. Modular plants with capacities as low as 25 tons per day have been built. Mass burn technologies represent over 75% of all the MSW-to-energy facilities constructed in the United States to date. The major components of a mass burn facility include refuse receiving and handling, combustion and steam generation, flue gas cleaning, power generation, condenser cooling water, residue hauling, and storage.
Materials recovery facility: A recycling facility for municipal solid waste.
MBF: One thousand board feet of lumber.
MC: See moisture content.
MCDB: See moisture content, dry basis.
MCWB: See moisture content, wet basis.
Mean annual increment: The annual average growth rate for a tree, computed over its entire life cycle.
Megawatt: (MW) The electrical unit of power that equals one million Watts (1,000 kW).
Merchantable: Logs from which at least of the volume can be converted into sound grades of lumber ("standard and better" framing lumber).
Mesophilic: An optimum temperature for bacterial growth in an enclosed digester (25° to 40°C).
Methane: An odorless, colorless, flammable gas with the formula CH4 that is the primary constituent of natural gas.
Methanogen: A methane-producing organism.
Methanol: Methyl alcohol having the chemical formula CH30H. Methanol is usually produced by chemical conversion at high temperatures and pressures. Wood alcohol. Although usually produced from natural gas, methanol can be produced from gasified biomass (syngas).
Methyl tertiary butyl ether: (MTBE) An ether manufactured by reacting methanol and isobutylene. MTBE has high octane and low volatility. Used as a fuel oxygenate.
Metric ton: (or tonne) 1000 kilograms. 1 metric ton = 2,204.62 lb = 1.023 short tons.
mg/l: Milligrams per liter.
MGD: Million gallons per day.
Microalgae: Unicellular, photosynthetic aquatic plants.
Micron: One thousandth of a millimeter.
Mid seral treatment: A treatment in which a stand of predominately mid seral species will be established.
Mid seral species: Shade intolerant species, primarily Douglas-fir trees and vine maple shrubs. These species typically follow the early seral species in natural succession.
Mill/kWh: A common method of pricing electricity. Tenths of a cent per kilowatt hour.
Mill residue: Wood and bark residues produced in processing logs into lumber, plywood, and paper.
Mill: A tenth of a cent ($0.001).
Mitigation: Steps taken to avoid or minimize negative environmental impacts. Mitigation can include: avoiding the impact by not taking a certain action; minimizing impacts by limiting the degree or magnitude of the action; rectifying the impact by repairing or restoring the affected environment; reducing the impact by protective steps required with the action; and compensating for the impact by replacing or providing substitute resources.
MMBF: One million board feet.
MMBtu: One million British thermal units.
Moisture content, wet basis: Moisture content expressed as a percentage of the weight of wood as-received. Expressed as:
weight of wet sample - weight of dry sample
--------------------------------------------------     x 100
weight of wet sample
Moisture Content: (MC) The weight of the water contained in wood, usually expressed as a percentage of weight, either oven-dry or as received.
Moisture content, dry basis: Moisture content expressed as a percentage of the weight of oven-dry wood.
weight of wet sample - weight of dry sample
----------------------------------------------------- x 100
weight of dry sample
Monoculture: The cultivation of a single species crop.
Mortality: The volume of sound wood in trees that have died from natural causes.
MRF: See materials recovery facility.
mscf: One thousand standard cubic feet.
Mscf: One million standard cubic feet.
MSW: See municipal solid waste.
Municipal solid waste: (MSW) Garbage. Refuse offering the potential for energy recovery; includes residential, commercial, and institutional wastes.
MWa: See average megawatt.
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NAAQS: See National Ambient Air Quality Standards.
National Ambient Air Quality Standards: (NAAQS) Federal standards established by the Clean Air Act.
National Environmental Policy Act: (NEPA) A federal law enacted in 1969 that requires all federal agencies to consider and analyze the environmental impacts of any proposed action. NEPA requires an environmental impact statement for major federal actions significantly affecting the quality of the environment. NEPA requires federal agencies to inform and involve the public in the agency´s decision making process and to consider the environmental impacts of the agency´s decision.
National Pollution Discharge Elimination System: (NPDES) The federal water quality program administered in Oregon by the DEQ.
National Forest Management Act: A federal law passed in 1976 as an amendment to the Forest and Rangeland Renewable Resources Planning Act requiring the preparation of Regional Guides and Forest Plans and the preparation of regulations to guide that development.
National Emissions Standards for Hazardous Pollutants: (NESHAPS) Federal standards that control pollutants considered toxic to humans.
Natural gas: A mixture of gaseous hydrocarbons, primarily methane, occurring naturally in the earth. Used as fuel.
Neat fuel: Fuel that is free from admixture or dilution with other fuels.
NEPA: See National Environmental Policy Act.
Nephelometric turbidity unit: A measurement unit of the clarity of water, dependent on the amount of suspended matter.
Nesting habitat: See spotted owl habitat.
Net billing: The arrangement by which the Bonneville Power Administration financed the cost of nuclear power plants. Utilities that owned shares in the projects, and paid a share of the costs, assigned to BPA all or part of the generating capability of the power plants. BPA, in turn, credited the wholesale power bills of those utilities to cover the costs of their shares in the projects. BPA then sold the power output of the plants by averaging their higher cost with lower cost hydropower.
Net heating value: (NHV) The potential energy available in the fuel as received, taking into account the energy loss in evaporating and superheating the water in the sample. Expressed as
NVH = (HHV x (1- MC / 100)) - (LH(2)O x MC / 100)
Net present value: The sum of the costs and benefits of a project or activity. Future benefits and costs are discounted to account for interest costs.
New Source Performance Standards: (NSPS) Federal standards for very large new sources of air pollution.
NFMA: See National Forest Management Act.
Nitrogen fixation: The transformation of atmospheric nitrogen into nitrogen compounds that can be used by growing plants.
Nitrogen oxides: (NOx) Regulated air pollutants, primarily NO and NO2. Nitrogen oxides are precursors to the formation of smog and contribute to the formation of acid rain.
Nonattainment area: (NAA) A geographic area in which air quality is worse than that allowed by federal air pollution standards.
Noncommercial species: Tree species that do not normally develop into suitable trees for conventional forest products because of small size, poor form, or inferior quality.
Noncondensing, controlled extraction turbine: A turbine that bleeds part of the main steam flow at one (single extraction) or two (double extraction) points.
NTU: See nephelometric turbidity unit.
Null hypothesis: The assumption that any observed difference between two samples of a statistical population is purely accidental and not due to systematic causes.
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Octane enhancer: Any substance that is added to gasoline to increase octane.
ODFW: Oregon Department of Fish and Wildlife.
OEM: Original equipment manufacturer.
Offset: See emission offset.
Old growth: Timber stands with the following characteristics: large mature and over-mature trees in the overstory, snags, dead and decaying logs on the ground and a multi-layered canopy with trees of several age classes.
Opacity: The degree to which smoke or particles emitted into the air reduce the transmission of light and obscure the view of an object in the background.
Organic: Derived from living organisms.
Organic compounds: Chemical compounds based on carbon chains or rings and also containing hydrogen, with or without oxygen, nitrogen, and other elements.
Organic level: The amount of organic matter prescribed to be left after logging.
Oven dry: See bone dry.
Oven dry ton: (ODT) An amount of wood that weighs 2,000 pounds at zero percent moisture content.
Overnight capital cost: The capital cost of a project if it could be constructed overnight. This cost does not include the interest cost of funds used during construction.
Overstory: The portion of the trees forming the upper or uppermost canopy in a forest stand.
Oxygenate: A gasoline fuel additive containing hydrogen, carbon and oxygen. The oxygen content promotes more complete combustion of gasoline, which reduces tailpipe emissions of carbon monoxide.
Oxygenated gasoline: Gasoline containing an oxygenate.
Ozone: Tropospheric ozone (ground-level ozone), or smog, is formed when volatile organic compounds, oxygen and nitrogen oxides react in the presence of sunlight. Ground-level ozone is a pollutant and a respiratory irritant. Stratospheric ozone occurs in the upper atmosphere an protects the earth from the sun´s ultraviolet rays.
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Partial cut: A harvest method in which portions of a stand of timber are cut during a number of entries over time. Compare precommercial thinning.
Particulate: A small, discrete mass of solid or liquid matter that remains individually dispersed in gas or liquid emissions. Particulates take the form of aerosol, dust, fume, mist, smoke or spray. Each of these forms has different properties.
Particulate emissions: Fine liquid or solid particles discharged with exhaust gases. Usually measured as grains per cubic foot or pounds per million Btu input.
Passive solar energy system: Solar heating or cooling that uses natural energy flows to transfer heat.
PCB´s: Polychlorinated biphenyls. A group of organic compounds. PCB´s are highly toxic to aquatic life. They persist in the environment for long periods of time, and they are bioaccumulants.
Peak flow: The highest flow of water attained during a particular flood for a given stream or river.
Percolation: The filtering of a liquid passed through a medium with many fine spaces.
PETS: Proposed, endangered, threatened, or sensitive species.
pH: A measure of acidity or alkalinity. A pH of 7 represents neutrality. Acid substances have lower pH. Basic substances have higher pH.
Photovoltaic: A system that converts direct sunlight to electricity using semi-conductor materials.
Piling unmerchantable material: (PUM) A logging contract requirement to remove and pile unmerchantable woody material of a specified size.
Pilot scale: The size of a system between the small laboratory model size (bench scale) and a full-size system.
Plant association: A grouping of plant species, or a plant community, that recurs across the landscape. Plant associations are used as indicators of environmental conditions such as temperature, moisture, light, etc.
Plot: A forest area defined by its condition.
PM2.5: Particulate that is less than 2.5 microns in diameter.
PM10: Particulate that is less than 10 microns in diameter. These particulates are present in the smoke created by burning wood.
Polishing treatment: The final sewage treatment process to further reduce BOD5, suspended solids, and other pollutants.
Post-aeration: The introduction of oxygen into waste water to further reduce BOD and COD after secondary or advanced treatment.
Pound: Pound mass (sometimes abbreviated lb(m)). A unit of mass equal to 0.454 kilograms.
Pound of steam: One pound mass of water converted to steam.
Pound force: (sometimes abbreviated lb(f)) A force which will accelerate one pound mass at a rate of 32.2 ft/second(2).
Precommercial thinning: Thinning for timber stand improvement purposes, generally in young, densely stocked stands. Precommercial thinning operations are not considered partial cuts.
Prescription: Specific written directions for forest management activities.
Present value: The worth of future receipts or costs expressed in current value. To obtain present value, an interest rate is used to discount future receipts or costs.
Prevention of significant deterioration: (PSD) Under the Clean Air Act, a planning and management process for air quality when a new source of air pollution is proposed in an area where ambient air quality is better than applicable standards (areas of special importance).
Process heat: Heat used in an industrial process rather than for space heating or other housekeeping purposes.
Producer gas: Fuel gas high in carbon monoxide (CO) and hydrogen (H2), produced by burning a solid fuel with insufficient air or by passing a mixture of air and steam through a burning bed of solid fuel.
Productive machine hours: That portion of scheduled operating hours during which a machine performs its designated functions, excluding time to transport the machine and operational or mechanical delays.
Programmed timber harvest: A timber harvest scheduled by a management plan to occur at a certain rate.
Proof: A measure of ethanol content. 1-percent ethanol content equals 2 proof.
Proximate analysis: An analysis which reports volatile matter, fixed carbon, moisture content, and ash present in a fuel as a percentage of dry fuel weight.
PSD: See prevention of significant deterioration.
psi: Pounds force of pressure per square inch.
psia: Pounds force of pressure per square inch absolute (including atmospheric pressure).
psig: Pounds force of pressure per square inch gauge (excluding atmospheric pressure).
Public utility district: (PUD) A publicly owned energy producer or distributor. PUDs operate as special government districts under the authority of elected commissions. They are not regulated by public utility commissions.
Public utility commissions: State agencies that regulate investor-owned utilities operating in the state.
Public Utility Regulatory Policies Act: (PURPA) A federal law requiring a utility to buy the power produced by a qualifying facility at a price equal to that which the utility would otherwise pay if it were to build its own power plant or buy power from another source.
Publicly Owned Treatment Works Permit: (POTW) A permit that regulates discharges to publicly owned sewage treatment plants.
Pulp chips: Timber or residues processed into small pieces of wood of more or less uniform dimensions with minimal amounts of bark.
PUM: See piling unmerchantable material.
PURPA: See Public Utility Regulatory Policies Act.
Pyrolysis: The thermal decomposition of biomass at high temperatures (greater than 400 degrees Fahrenheit, or 200 degrees Celcius) in the absence of air. Also called destructive distillation. The end product of pyrolysis is a mixture of solids (char), liquids (oxygenated oils), and gases (methane, carbon monoxide, and carbon dioxide) with proportions determined by operating temperature, pressure, oxygen content, and other conditions.
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Quad: One quadrillion Btu (1015 Btu). An energy equivalent to approximately 172 million barrels of oil.
Qualifying facility: A power production facility that qualifies for special treatment under the Public Utility Regulatory Policies Act. A qualifying facility must generate its power using cogeneration, biomass, waste, geothermal energy or renewable resources, such as solar and wind. PURPA prohibits utilities from owning majority interest in qualifying facilities.
Quaternary: The present period, forming the latter part of the Cenozoic Era, originating about 1 million years ago and including the Recent and Pleistocene epochs.
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Rate schedule: A price list showing how the electric bill of a particular type of customer will be calculated by an electric utility company.
RCRA: See Resource Conservation and Recovery Act.
RDF: See refuse-derived fuel.
Recirculation: Returning a fraction of the effluent outflow to the inlet to dilute incoming wastewater.
Record of Decision: (ROD) The decision document for an environmental impact statement (EIS). Separate from the EIS itself, this document states the decision, states the reasons for the decision, identifies all alternatives and states compliance with applicable laws.
Recovery boiler: A pulp mill boiler in which lignin and spent cooking liquor (black liquor) is burned to generate steam.
Reformulated gasoline: (RFG) Gasoline that has altered composition or characteristics to reduce emissions of pollutants from vehicles in accordance with the Clean Air Act.
Refractory Lining: A lining, usually of ceramic, capable of resisting and maintaining high temperatures.
Refuse-derived fuel: (RDF) Fuel prepared from municipal solid waste. Noncombustible materials such as rocks, glass, and metals are removed, and the remaining combustible portion of the solid waste is chopped or shredded. RDF facilities process between 100 and 3000 tons of MSW per day.
Regeneration harvest: A timber harvest method that removes selected trees in the existing stand to a density that allows for the establishment of a new even-aged stand below.
Regeneration with reserves: Similar to a regeneration harvest, except that a number of green trees are left standing to meet other resource needs such as wildlife habitat. The number of trees left is usually specified as a certain number of trees per acre.
Reid vapor pressure: (RVP) A standard measurement of a liquid´s vapor pressure at 100 degrees Fahrenheit. An indication of the propensity of the liquid to evaporate.
Reinjection: The feeding of unburned char and fly ash obtained from mechanical collectors into the furnace for further combustion.
Renewable energy source: An energy source that is replenished continuously in nature or that is replaced after use through natural means. Sustainable energy source. Renewable energy sources include the sun, the winds, flowing water, biomass and geothermal energy.
Repetition/replication: There are four plots in a repetition/replication, the early, mid and late seral treatment plots and a control plot. A repetition/replication is also called a "block." There should be at least three repetitions/ replications in a research study to obtain statistical reliability.
Reserve margin: The amount by which the utility´s total electric power capacity exceeds maximum electric demand.
Resident fish: Fish species that complete their entire life cycle in freshwater. Non-anadromous fish. An example is rainbow trout.
Resource values: A resource, natural or social, that is found in an area. Resource values may have varying levels of significance.
Resource Conservation and Recovery Act: (RCRA) A federal law regulating solid and hazardous waste. RCRA governs the generation, storage, treatment, transport, and disposal of hazardous waste.
Retrofitting: The application of conservation, efficiency, or renewable energy technologies to existing structures.
Return on investment: (ROI) The interest rate at which the net present value of a project is zero. Multiple values are possible.
Riparian area: An area of land directly influenced by water. An ecosystem that is transitional between land and water ecosystems. Riparian areas usually have visible vegetative or physical characteristics reflecting the influence of water. River sides, lake borders, and marshes are typical riparian areas.
Riparian buffer: Riparian areas that are managed to protect the aquatic and riparian ecosystem. A riparian buffer protects water quality and temperature, habitat along the banks, upland habitat for aquatic and riparian species, and some or all of the floodplain.
ROD: See Record of Decision.
ROI: See return on investment.
Rotation: The number of years allotted to establish and grow a forest stand to maturity.
Rough trees: Live trees of commercial species which do not contain a sawlog because of roughness, poor form, splits, or cracks. Includes all living trees of noncommercial species.
Roundwood: Logs, bolts, or other round sections cut from trees.
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Salvage logging: The harvest of dead, dying, damaged or weak trees after a forest fire to prevent the spread of disease or insects and to reduce the risk of high intensity fire.
Saturated steam: Steam at the temperature that corresponds to its boiling temperature at the same pressure.
Sawlog: A log meeting minimum commercial requirements of diameter, length, and defect. The usual commercial requirements are a minimum of 8´ long with an inside bark diameter of 6" for softwoods and 8" for hardwoods.
Sawtimber: Live trees of commercial species containing at least one 12´ sawlog or two noncontiguous 8´ logs. Softwoods must be at least 9" in diameter and hardwoods at least 11" in diameter.
Scaled sale: A type of timber sale contract that specifies measuring or scaling of the included timber after removal. Scaling determines the number of board feet or c-units to be paid for at contract rates.
SCF: Standard cubic foot.
SCFM: Standard cubic foot per minute.
Scoping: A first step in the NEPA process and in the river planning process. Scoping is a means of identifying issues and concerns, their significance, and the range of alternatives.
Scrubber: A device to clean combustible gas or stack gas by the spraying of water.
Second growth: A second generation of timber of merchantable age.
Secondary succession: The progression of plant communities following disturbances such as fire, windthrow and timber harvesting. See Succession.
Sedimentation: A process in which material carried in suspension by water flows into streams and rivers, increasing turbidity and eventually settling to the bottom.
Selection cutting: The periodic removal at short intervals of the oldest and largest trees in the stand, individually or in small groups.
Sensitive species: See Threatened, endangered, and sensitive species.
Seral stages: The series of relatively transitory plant communities that develop during ecological succession from bare ground to the climax stage.
Sewage: The waste water from domestic, commercial and industrial sources carried by sewers.
Shaft horsepower: A measure of the actual mechanical energy per unit time delivered to a turning shaft. 1 shaft horsepower = 1 electric horsepower = 550 ft-lb/second.
Short rotation energy plantation: Plantings established and managed under short-rotation intensive culture practices.
Short rotation intensive culture: Intensive management and harvesting at 2 to 10 year intervals of cycles of specially selected fast- growing hardwood species for the purpose of producing wood as an energy feedstock.
Short ton: 2000 pounds. A ton, as commonly used in the U.S. and Canada.
Silviculture: The theory and practice of forest stand establishment and management.
SIP: See State Implementation Plan.
Site preparation: Various treatments applied to a harvested area to promote regeneration of the site.
Site potential tree: A tree that has attained the average maximum height possible given site conditions where it occurs.
Skidder: A self-propelled machine to transport harvested trees or logs from the stump area to the landing or work deck.
Slash: The unmerchantable material left on site subsequent to harvesting a timber stand, including tops, limbs, cull sections.
Slow pyrolysis: Thermal conversion of biomass to fuel by slow heating to less than 450°C in the absence of oxygen.
Sludge: The mixture of organic and inorganic substances separated from sewage.
Small Scale Energy Loan Program: (SELP) In Oregon, a low-cost loan and technical assistance program administered by the Oregon Department of Energy.
Smog: A visible haze caused by particulate matter and ground-level ozone.
Snag: Any standing dead, partially dead or defective tree. A hard snag is composed primarily of sound wood. A soft snag is composed primarily of wood in advanced stages of decay and deterioration.
Socioeconomic: Relating to social or economic factors or to a combination of both social and economic factors.
Solvent extraction: A method of separation used to purify vegetable oils.
Source Emission Reduction Plan: (SERP) A contingency plan developed to reduce emissions during an air quality emergency.
Spawning gravel: Sorted, clean gravel patches of a size appropriate for the needs of resident or anadromous fish.
Specific work:
work output
mass flow
Spotted owl habitat:
  • Dispersal habitat: Forest vegetation with at least 40% canopy closure and an average stand diameter of 11". These stands are used by the owls to disperse or move from one area of nesting or foraging habitat to another.
  • Foraging habitat: Forest vegetation with the age class, species of trees, structure, sufficient area, and adequate food source to meet the needs of foraging spotted owls. This type of habitat includes nesting habitat, but it also includes younger stands, generally greater than 18" DBH with some of the structural components of nesting habitat.
  • Nesting habitat: Forest vegetation with the age class, species of trees, structure, sufficient area, and adequate food source to meet the needs of a nesting pair of spotted owls. This type of habitat is found generally in older forests with multiple canopies, large diameter trees, and abundant large standing and down woody debris.
Spreader stoker furnace: A furnace in which fuel is automatically or mechanically spread. Part of the fuel is burned in suspension. Large pieces fall on a grate.
Stand conversion: The conversion of a noncommercial stand of timber to a commercial stand.
Stand: (tree stand, timber stand) A community of trees managed as a unit. Trees or other vegetation occupying a specific area, sufficiently uniform in species composition, age arrangement, and condition as to be distinguishable from the forest or other cover on adjoining areas.
Stand density: The number or mass of trees occupying a site. It is usually measured in terms of stand density index or basal area per acre.
Standards and guidelines: Bounds or constraints within which all practices in a given area will be carried out, in achieving the goals and objectives for that area. Standards and guidelines provide environmental safeguards and also describe constraints prescribed by law.
State Implementation Plan: A state plan required by the Clean Air Act to bring nonattainment areas into compliance with federal ambient air quality standards.
Steam conversion factors: (approximations)
1 pound of steam = 1,000 Btu = .3 kW. 10,000 lbs/hr steam = 300 boiler horsepower.
Steam turbine: A device for converting energy of high-pressure steam (produced in a boiler) into mechanical power which can then be used to generate electricity.
Stillage: The grains and liquid effluent remaining after distillation.
Stoichiometric condition: That condition at which the proportion of the air-to-fuel is such that all combustible products will be completely burned with no oxygen remaining in the combustion air.
Stream class: Classification of streams based on the present and foreseeable uses made of the water, and the potential effects of on-site changes on downstream uses. Four classes are defined:
  • Class I: Perennial or intermittent streams that provide a source of water for domestic use. Class I streams are used by large numbers of anadromous fish or significant sports fish for spawning, rearing, or migration, or are major tributaries to other Class I streams.
  • Class II: Perennial or intermittent streams that are used by fish for spawning, rearing, or migration. Class II streams may be tributaries to Class I streams or other Class II streams.
  • Class III: All other perennial streams not meeting higher class criteria.
  • Class IV: All other intermittent streams not meeting higher class criteria.
Structure: Arrangement of components in a forest. Vertical structural layers include overstory trees, understory trees, snags, shrubs, and herbs. Horizontal structural layers include number and species of trees, spacing of trees, and number and species of shrubs and herbs. Forest structure affects ecological processes and biodiversity.
Stumpage: (1) Standing live or dead uncut trees. (2) The value or rate paid to purchase standing trees for harvest.
Subdrainage: A land area (basin) bounded by ridges or similar topographic features, encompassing only part of a watershed.
Substrate: The material forming the underlying layer of streams. Substrates may be bedrock, gravel, boulders, sand, or clay.
Succession: A series of dynamic changes by which one group of organisms succeeds another through stages leading to potential natural community or climax. An example is the development of series of plant communities called seral stages following a major disturbance such as fire or timber harvesting.
Sunk cost: A cost already incurred and therefore not considered in making a current investment decision.
Superheated steam: Steam at a given pressure which is above the temperature which corresponds to boiling temperature at that given pressure.
Surplus electricity: Electricity produced by cogeneration equipment in excess of the needs of an associated factory or business.
Suspended solids: Waste particles suspended in water. Suspended solids can harbor harmful microorganisms and toxic chemicals. Suspended solids cloud the water and make disinfection more difficult and costly.
Sustainable: An ecosystem condition in which biodiversity, renewability, and resource productivity are maintained over time.
Sustained yield: The maintenance in perpetuity of regular, periodic harvest of wood resources from forest land without damaging the productivity of the land.
Syngas: A syntheses gas produced through gasification of biomass. Syngas is similar to natural gas and can be cleaned and conditioned to form a feedstock for production of methanol.
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TE&S species: See threatened, endangered and sensitive species.
Therm: A unit of energy equal to 100,000 British thermal units; used primarily for natural gas.
Thermal resource: A facility that produces electricity by using a heat engine to power an electric generator. The heat may be supplied by the combustion of coal, oil, natural gas, biomass, or other fuels, including nuclear fission, solar, or geothermal resources.
Thermal efficiency:
useful work and energy out
-------------------------------------     x 100
higher heating value of input fuel
Thermal cover: Vegetative condition, generally with greater than 70% canopy closure and 40 feet in height, that can significantly ameliorate weather effects such as wind, heat, cold, and snow. Used by wildlife in winter.
Thermochemical conversion process: Chemical reactions employing heat to produce fuels.
Threatened, endangered and sensitive species: Formal classifications of species.
  • Sensitive: Species for which population viability is a concern. Sensitive species are not federally designated under the Endangered Species Act.
The U.S. Fish and Wildlife Service, after study, makes the following designations:
  • Candidate: Species under consideration for listing as endangered or threatened but for which conclusive data on biological vulnerability are not currently available to support listing. Also known as Category 2 species.
  • Endangered: A species in danger of becoming extinct throughout all or a significant portion of its range.
  • Threatened: A species likely to become endangered in the foreseeable future.
  • Proposed: Those species named in formal documents published in the Federal Register under the direction of the Endangered Species Act and 50 CFR 402.2 but which have not yet been listed as endangered or threatened.
Timber stand improvement: Intermediate pruning, weeding, and thinning of a stand of timber prior to its reaching mature rotation age to improve growing conditions and control stand composition.
Timberland: Forest land capable of producing 20 cubic feet of wood per acre per year.
Tipping fee: A fee for disposal of waste.
Topping cycle: A cogeneration system in which electric power is produced first. The reject heat from power production is then used to produce useful process heat.
Topping and back pressure turbines: Turbines which operate at exhaust pressure considerably higher than atmospheric (noncondensing turbines). These turbines are often multistage types with relatively high efficiency.
Total suspended particulates: The quantity of solid particles in a gas or exhaust stream. Any finely divided material (solid or liquid) that is airborne with a diameter smaller than a few hundred micrometers.
Toxic substances: A chemical or mixture of chemicals that presents a high risk of injury to human health or to the environment.
Transmission: The process of long-distance transport of electrical energy, generally accomplished by raising the electric current to high voltages.
Traveling grate: A type of furnace in which assembled links of grates are joined together in a perpetual belt arrangement. Fuel is fed in at one end and ash is discharged at the other.
Tree measurement sale: A type of timber sale contract in which the buyer and seller agree upon the volume at the time of the sale.
TSP: See total suspended particulates.
Turbidity: The relative clarity of water, which may be affected by material in suspension in the water.
Turbine: A machine for converting the heat energy in steam or high temperature gas into mechanical energy. In a turbine, a high velocity flow of steam or gas passes through successive rows of radial blades fastened to a central shaft.
Turn of logs: A group of logs yarded at the same time by the same machine.
Turn down ratio: The lowest load at which a boiler will operate efficiently as compared to the boiler´s maximum design load.
Turnkey system: A system which is built, engineered, and installed to the point of readiness for operation by the owner.
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Ultimate analysis: A description of a fuel´s elemental composition as a percentage of the dry fuel weight.
Understory: The trees and other woody species growing under a relatively continuous cover of branches and foliage formed by the overstory trees.
Uniform Mechanical Code: (UMC) A code sponsored by the International Association of Plumbing and Mechanical Officials and the International Conference of Building Officials, adopted and amended by the Oregon Department of Commerce. The UMC contains requirements for the installation and maintenance of heating, ventilating, cooling, and refrigeration systems.
Uniform Building Code: (UBC) A building code published by the International Conference of Building Officials, adopted and amended by Oregon Department of Commerce. The UBC covers the fire, life and structural safety aspects of all buildings and related structures.
Unit (timber): A timber harvest area with defined boundaries. The area is managed as a unit for harvest and subsequent management activities.
Unit (fuel or pulp): A bulk measure of hog fuel or pulp chips containing 200 cubic feet. A unit contains varying amounts of solid material depending on the amount of compaction. It is customary to weigh material, correct for moisture, and calculate the number of bone dry tons.
Unmerchantable wood: Material which is unsuitable for conversion to wood products due to poor size, form, or quality.
Unsuitable areas: Areas not appropriate for timber harvest due to fragile or shallow soils, scenic values, special wildlife habitat areas, and riparian or wetland values, among other possible reasons.
Urban growth boundary: A land use boundary surrounding a city within which urban land uses are allowed.
USFS: United States Department of Agriculture Forest Service.
USFWS: United States Fish and Wildlife Service.
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Valley segment: That portion of a stream network with similar morphologies and governing geomorphic processes identified by valley bottom and sideslope geomorphic characteristics.
VOC: see Volatile organic compounds.
Volatile organic compounds: (VOC) Non-methane hydrocarbon gases. Released during combustion or evaporation of fuel.
Volatiles: Substances that are readily vaporized.
Volatility: The tendency of a liquid to pass into the vapor state at a given temperature. Vapor pressure.
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Waste streams: Unused solid or liquid by- products of a process.
Water-cooled vibrating grate: A boiler grate made up of a tuyere grate surface mounted on a grid of water tubes interconnected with the boiler circulation system for positive cooling. The structure is supported by flexing plates allowing the grid and grate to move in a vibrating action. Ashes are automatically discharged.
Watermaster: In Oregon, an official of the Water Resources Department who allocates available surface or groundwater in the state.
Watershed: The drainage basin contributing water, organic matter, dissolved nutrients, and sediments to a stream or lake.
Watt: The common base unit of power in the metric system. One watt equals one joule per second. It is the power developed in a circuit by a current of one ampere flowing through a potential difference of one volt. One Watt = 3.413 Btu/hr.
Wetlands: Lands where saturation with water is the primary factor determining soil development and the kinds of plant and animal communities living on or under the surface.
Wheeling: The process of transferring electrical energy between buyer and seller by way of an intermediate utility or utilities.
Whole-tree harvesting: A harvesting method in which the whole tree (above the stump) is removed.
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No terms begin with "X."
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Yarder: A machine used in yarding timber.
Yarding unmerchantable material: (YUM) A logging contract requirement to remove and pile unmerchantable woody material of a specified size. Usually required in timber sale contracts on publicly-owned land.
Yarding: The initial movement of logs from the point of felling to a central loading area or landing.
YUM: See Yarding unmerchantable material
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No terms begin with "Z."
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