bacillus A rod-shaped bacterium. A genus of the family Bactillaceae.
backflow A reverse flow condition, created by a difference in water pressures, which causes water to flow back into the distribution pipes of a potable water supply from any source or sources other than an intended source. Also see backsiphonage and cross-connection.
backflow connection Any arrangement whereby backflow can occur.
backflow preventer See backflow prevention device.
backflow prevention device Any approved device, method, or type of construction intended to prevent backflow into a waterworks. See backflow.
background concentration A concentration of a substance in a particular environment that is indicative of minimal influence by anthropogenic (human) sources.
background level In toxic substances monitoring, the average presence of a substance in the environment, originally referring to naturally occurring phenomena.
backing winds Winds which shift in a counterclockwise direction with time at a given location (e.g. from southerly to southeasterly), or change direction in a counterclockwise sense with height (e.g. westerly at the surface but becoming more southerly aloft).
back pressure A pressure that can cause water to backflow into the water supply when a user's water system is at a higher pressure than the public water system.
back-pressure valve
backsight A rod reading taken on a point of known elevation, a benchmark or a turning point. Backsights are added to the known elevation to arrive at the height of the instrument. With a known height of the instrument, the telescope can be used to determine the elevation of other points in the vicinity.
backsiphonage A form of backflow caused by a negative or below atmospheric pressure within a water system. See also backflow and cross connection.
backwash To remove entrapped solids in filter media by reversing the flow of water through the filter.
backwashing The process of reversing the flow of water back through the filter media to remove the entrapped solids.
backwater The resulting high water surface in a given stream due to downstream obstruction or high stages in an intersecting stream.
backwater curve The longitudinal profile of the surface of a liquid in a nonuniform flow in an open channel, when the water surface is not parallel to the invert owing to the depth of water having been increased by the interposition of an obstruction such as a dam or weir. The term is sometimes used in a generic sense to denote all water surface profiles; or for profiles where the water is flowing at depths greater than the critical.
backwater effect The effect which a dam or other obstruction has in raising the surface of the water upstream from it.
backwater flooding Upstream flooding caused by downstream conditions such as channel restriction and/or high flow in a downstream confluence stream.
bacteria (sing. bacterium) Microscopic, one-celled, plant-like organisms. Virtually all bacteria lack chlorophyll and they multiply by binary fission.
bactericidal Capable of killing bacteria.
bactericide A bactericidal agent (germicide).
bacteriophage A virus that infects bacteria.
bacteriostatic Preventing the growth of bacteria without killing them.
baffle A flat board or plate, deflector, guide or similar device constructed or placed in flowing water or slurry systems to cause more uniform flow velocities, to absorb energy, and to divert, guide, or agitate liquids.
baffle chamber In incinerator design, a chamber designed to promote the settling of fly ash and coarse particulate matter by changing the direction and/or reducing the velocity of the gases produced by the combustion of the sludge or refuse.
baghouse A dust-collection chamber containing numerous permeable fabric filters through which the exhaust gases pass. Finer particulates entrained in the exhaust gas stream are collected in the filters for subsequent treatment/disposal.
baghouse filter Large fabric bag, usually made of glass fibers, used to eliminate intermediate and large (greater than 20 microns in diameter) particles. This device operates like the bag of an electric vacuum cleaner, passing the air and smaller particles while entrapping the larger ones.
bailer A ten- to twenty-foot-long pipe equipped with a valve at the lower end. A bailer is used to remove slurry from the bottom or the side of a well as it is being drilled.
bail piezometer test A single well test to determine the in-situ hydraulic conductivity of an aquifer by the instantaneous removal of a known quantity of water from a well, and the subsequent measurement of the recovery as a function of time.
baling Compacting solid waste into blocks to reduce volume and simplify handling.
ballistic separator A machine that sorts organic from inorganic matter for composting.
ball valve A valve regulated by the position of a free-floating ball that moves in response to fluid or mechanical pressure.
band application The spreading of chemicals over, or next to, each row of plants in a field.
bandwidth Maximum frequency that can be used to transmit a communication signal without excessive distortion. Measured in Hertz or cycles per second. The more information contained in a signal, the more bandwidth it requires for distortion-free transmission.
bank The margins of a channel. Banks are called right or left as viewed facing in the direction of the flow.
bank full stage/elevation An established river stage, or water surface elevation, at a give location along a river which is intended to represent the maximum water level which will not overflow the river banks or cause any significant damages from flooding.
banking A system for recording qualified air emission reductions for later use in bubble, offset, or netting transactions. (See emissions trading.)
bar chart A visual display of the size of the different categories of a variable. Each category or value of the variable is represented by a bar.
baroclinic When isobaric surfaces of a fluid are not parallel with density surfaces.
baroclinic zone A region in which a temperature gradient exists on a constant pressure surface. Baroclinic zones are favored areas for strengthening and weakening systems.
barometer An instrument for determining the pressure of the atmosphere.
barotropic When isobaric surfaces of a fluid are parallel with density surfaces.
barotropic system A weather system in which temperature and pressure surfaces are coincident, i.e., temperature is uniform (no temperature gradient) on a constant pressure surface.
barrage Any artificial obstruction placed in water to increase water level or divert it. Usually the idea is to control peak flow for later release.
barrier coating A layer of a material that obstructs or prevents passage of something through a surface that is to be protected, e.g. grout, caulk, or various sealing compounds; sometimes used with polyurethane membranes to prevent corrosion or oxidation of metal surfaces, chemical impacts on various materials, or, for example, to prevent radon infiltration through walls, cracks, or joints in a house.
barrier island An island, formed by long, narrow strips of sand, that protect inland areas from ocean waves and storms.
bar screen In wastewater treatment, a screening device consisting of metal rods, at a fixed distance apart, placed across a flow channel to remove large solids.
basal application In pesticides, the application of a chemical on plant stems or tree trunks just above the soil line.
basal area 1) The area of cross section of a tree usually referring to the section at breast height (4 ½ feet above the ground). 2) The summed basal area per acre or larger unit occupied by stems of one species or forest type.
base A substance which neutralizes an acid. A substance which furnishes hydroxyl (OH) ions and a positive ion, usually a metal. An ion which will combine with hydrogen ions. An alkali.
base flood The national standard for floodplain management is the base, or one percent chance, flood. This flood has at least one chance in 100 of occurring in any given year. It is also called a 100 year flood.
baseflow That part of a stream discharge that originates as ground water seeping into the stream. Also known as dry-weather flow and groundwater flow.
base level The level (elevation) at which a stream or river can erode no more usually sea level.
baseline An established value or trend used for comparison when conditions are altered, as in the introduction of water conservation measures.
baseline audiogram The audiogram obtained from an audiometric examination administered prior to employment or within the first 30 days of employment that is preceded by a period of at least 14 hours of quiet. The baseline audiogram is the audiogram against which subsequent audiograms will be compared for the calculation of significant threshold shift.
baseline monitoring The establishment and operation of a designed surveillance system for continuous or periodic measurements and recording of existing and changing conditions that will be compared with future observations.
baseline profile Used for a complete survey of the environmental conditions and organisms existing in a region prior to unnatural disturbances.
baseline study See baseline profile.
base metal A metal (such as iron) which reacts with dilute hydrochloric acid to form hydrogen. See also noble metal.
base station A computer which accepts radio signals from ALERT gaging sites, decodes the data, places the data in a database, and makes the data available to other users.
base width The time duration of a unit hydrograph.
base year A year used as the basis of reference of a series of index numbers.
basic hydrologic data
basin 1) A depression in the Earth's surface that collects sediment. 2) 3) 4) 5) 6) See drainage basin.
basin and range physiography A region characterized by a series of generally north-trending mountain ranges separated by alluvial valleys.
basin boundary The topographic dividing line around the perimeter of a basin, beyond which overland flow (i.e., runoff) drains away into another basin.
basin lag The time it takes from the centroid of rainfall for the hydrograph to peak.
basin recharge Rainfall which adds to the residual moisture of the basin in order to help recharge the water deficit. Water absorbed into the soil which does not take the form of direct runoff.
BAT Best available technology.
batch process A treatment process in which a tank or reactor is filled, the water or wastewater is treated or a chemical solution is prepared, and the tank is emptied after an established reaction period. The tank may then be filled and the process repeated.
batch reactor A reactor used for a batch process in which flow is neither entering nor leaving on a continuous basis.
bathyal Of or related to lake and ocean bottoms of very deep water, e.g., below 300 meters in a lake or below 5,000 meters in the sea.
bay
battue The beating of woods and bushes to flush game.
baud rate The transmission rate at which data flows between computers. The baud rate is roughly equivalent to the number of bits per second (bps).
beach Depositional area at the shore of an ocean or lake covered by silt, sand, gravel, or larger rock fragments and extending into the water for some distance.
becquerel (Bq) The radioactivity unit of the international system of units. One becquerel equals one nuclear disintegration per second.
Bed 1) The layer of media in a treatment unit. 2) A layer of sediment or sedimentary rock. 3)
bedding Parallel layers of sediment or sedimentary rock (beds) that can be distinguished from each other by characteristics such as grain size and chemical composition. Most beds are deposited essentially horizontally.
bed load Sediment particles resting on or near the channel bottom that are capable of being transported with the flow of water.
bed material The sediment mixture of which a streambed, lake, pond, reservoir, or estuary bottom is composed.
bedrock The solid rock at the surface or underlying other surface materials.
bed sediment The material that temporarily is stationary in the bottom of a stream or other watercourse.
bed sediment and tissue studies Assessment of concentrations and distributions of trace elements and hydrophobic organic contaminants in streambed sediment and tissues of aquatic organisms to identify potential sources and to assess spatial distribution.
beggiatda A sulfur reducing filamentous bacteria that forms in the presence of concentrated organic matter and low dissolved oxygen.
benchmark (BM) A permanent point whose known elevation is tied to a national network. These points are created to serve as a point of reference. Benchmarks have generally been established by the USGS, but may have been established by other Federal or local agencies. Benchmarks can be found on USGS and other topographic maps. A tidal bench mark is one near a tide station to which the tide staff and tidal datums are referred. A geodetic bench mark identifies a surveyed point in the National Geodetic Vertical Network. Most geodetic bench mark disks contain the inscription VERTICAL CONTROL MARK NATIONAL GEODETIC SURVEY with other individual identifying information.
bench-scale tests Laboratory-scale testing of potential treatment or cleanup technologies.
beneficial use Any of a number of water uses or reuses of materials that are recognized by a political entity as valuable to society and worthy of protection, are defined by statutes, and may need to be protected against quality or quantity degradation. These water uses include, but are not necessarily limited to, domestic, municipal, agricultural, and industrial supply; cooling in thermoelectric power generation; and instream uses that include hydroelectric power generation; recreation; aesthetic enjoyment; navigation; and preservation and enhancement of fish, wildlife, and other aquatic resources or preserves.
benefit-cost analysis A comparison of total benefits to total costs, usually expressed in monetary terms, used to express efficiency and evaluate alternatives. See cost effectiveness and avoided cost.
benefit-cost ratio The arithmetic proportion of estimated annual benefits to average annual costs, insofar as the factors can be expressed in monetary terms. The relation of benefits to costs represents the degree of tangible economic justification of a project.
benefits Increase or gains, net of associated or induced costs, in the value of goods and services which result from conditions with the project as compared to conditions without the project.
benthic Of, relating to, or occurring at the bottom of lakes or oceans.
benthic invertebrates Insects, mollusks, crustaceans, worms, and other organisms without a backbone that live in, on, or near the bottom of lakes, streams, or oceans.
benthos Those organisms that live on the bottom of a body of water.
bentonite A colloidal clay, largely made up of the mineral sodium montmorillonite, a hydrated aluminum silicate. Because of its expansive property, bentonite is commonly used to provide a tight seal around a well casing.
berm A sloped wall or embankment (typically constructed of earth, hay bales, or timber framing) used to prevent inflow or outflow of material into/from an area.
best available control measures (BACM) A term used to refer to the most effective measures for controlling small or dispersed particulates from sources such as roadway dust, soot and ash from wood stoves and open burning of rush, timber, grasslands, or trash.
best available control technology (BACT) For any specific source, the necessary technology that would produce the greatest reduction of each pollutant regulated by the Clean Air Act, taking into account energy, environmental, economic and other costs.
best available technology (BAT) 1) The best technology treatment techniques or other means which are established from field and laboratory examination for efficiency. For the purposes of setting MCLs for synthetic organic chemicals, any BAT must be as least effective as granular activated carbon. 2) The best technology, treatment techniques, or other means which the Commissioner finds, after examination for efficacy under field and not solely under laboratory conditions and in conformance with applicable EPA regulations, are available (taking cost into consideration).
best demonstrated available technology (BDAT) As identified by EPA, the most effective commercially available means of treating specific types of hazardous waste. The BDATs may change with advances in treatment technologies.
best management practice (BMP) 1) A measure or activity that is beneficial, empirically proven, cost-effective, and widely accepted in the professional community. 2) Specifically, structural, nonstructural, and managerial techniques that are recognized to be the most effective and practical means to control nonpoint source pollutants, yet are compatible with the productive use of the resource to which they are applied. BMPs are used in both urban and agricultural areas and can be an important part of watershed management. 3)
best professional judgment The highest quality technical opinion developed after consideration of all reasonable, available and pertinent data or information that forms the basis for the standards, terms, and conditions of a design permit or requirement.
beta particle A charged particle emitted from a nucleus during radioactive decay. The beta particle, with a mass equal to 1/1837 that of a proton, is similar to an electron. Large amounts of beta radiation may cause skin burns and beta emitters are harmful if they enter the body. Beta particles from radioactive decay are easily stopped by a thin sheet of metal or plastic.
best track A subjectively smoothed path, versus a precise and very erratic fix-to-fix path, used to represent tropical cyclone movement. It is based on an assessment of all available data.
BGLB (Brilliant Green Lactose Bile Broth) The medium used for the Confirmed Test of the Multiple Tube Fermentation (MTF) Procedure.
bias 1) The degree to which the typical prediction is either too high or too low. 2) An inadequacy in experimental design that leads to results or conclusions not representative of the population under study.
bicarbonate alkalinity That part of the total alkalinity that is due to the bicarbonate ion (HCO3 –).
biennial report The state’s State Revolving Fund Report to EPA that contains information on how the State has met the goals and objectives of the previous two fiscal years as stated in the intended Use Plan and grant agrement.
billion In North America, 1,000,000,000.
bill of lading (b/l) The written order from a shipper to a carrier to move goods from one place to another. When available, this is the best source of shipping dates, origin, and name of shipper.
bimetallic corrosion Corrosion resulting from dissimilar metal contact; galvanic corrosion.
binding commitment A legal obligation by the state to a local recipient that defines the terms and the timing for assistance under the State Revolving Fund.
binding site The part of the antibody molecule that will specifically bind antigen.
bioaccumulants Substances that increase in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted. See biological magnification.
bioaccumulation The metabolic retention and concentration of a substance by an organism.
bioactivity The level of specific activity or potency as determined by animal model, cell culture, or in vitro biochemical assay.
bioassay A test which determines the ecological effects of a substance through the response of a test organism.
bioaugmentation The introduction of cultured microorganisms into wastewater or the subsurface environment for the purpose of enhancing bioremediation of organic contaminants. Generally the microorganisms are selected for their ability to degrade the organic compounds present at the remediation site. The culture can be either an isolated genus or a mix of more than one genera. Nutrients are usually also blended with the aqueous solution containing the microbes to serve as a carrier and dispersant. The liquid is introduced into the subsurface under natural conditions (gravity fed) or injected under pressure.
bioavailability The availability of a compound for biodegradation, influenced by the compound's location relative to microorganisms and its ability to dissolve in water.
biochemical Refers to chemical processes that occur inside or are mediated by living organisms.
biochemical oxygen demand (BOD) The amount of oxygen consumed by microorganisms (mainly bacteria) and by chemical reactions in the biodegradation of organic matter as determined by successive measurements of dissolved oxygen taken from standard test mixtures of water and wastewater under controlled temperatures. See BOD5.
biocide 1) Any chemical or agent that kills organisms. 2) A preservative (usually acid, to lower the pH) added to a water sample to prevent microbial degradation.
biocoenosis An ecological unit comprising both the plant and animal populations of a habitat; a biologic or biotic community.
bioconcentration The accumulation of a chemical in tissues of an organism (such as fish) to levels that are greater than the level in the medium (such as water) in which the organism resides. See bioaccumulation.
bioconversion The conversion of biomass to usable energy, as by burning solid fuel for heat, by fermenting plant matter to produce fuel, as ethanol, or by bacterial decomposition of organic waste to produce methanol.
biodegradable Can be oxidized into simple inorganic substances such as carbon dioxide and water by the action of microorganisms, such as bacteria. See biological oxidation.
biodegradation Decomposition of a substance into more elementary compounds by the biological oxidation of microorganisms, such as bacteria.
biodiversity The variety and variability among living organisms and the ecological complexes in which they occur. Diversity can be defined as the number of different items and their relative frequencies. For biological diversity, these items are organized at many levels, ranging from complete ecosystems to the biochemical structures that are the basis of heredity.
bioflocculation A condition whereby organic materials tend to be transferred from the dispersed form in wastewater to settleable material by mechanical entrapment and assimilation.
biogeochemical cycle A cycle dealing with the relationship between the chemical changes of the earth's crust of a given region and its flora and fauna, including the circulation of such elements as carbon, and nitrogen between the environment of the cells of living organisms.
biogeochemical cycling The movement of chemical elements from the physical environment to organisms in an ecosystem and back to the environment.
biohazard The health risk posed by the possible release of a pathogen into the environment.
biological concentration The active concentration of a substance (molecule or compound) by an organism as a result of normal activities, e.g., absorption or ingestion.
biological containment Characteristics of an organism that limit its survival and/or multiplication in the environment.
biological control In pest control, the use of animals and organisms that eat or otherwise kill or out-compete pests.
biological corrosion Corrosion that results from a reaction between the pipe material and organisms, such as bacteria, algae, and fungi.
biological diversity The number of kinds of organisms per unit area or volume; the biodiversity or richness of species in a given area.
biological examinations A microscopic survey of the types of microorganisms present in a sample.
biological filtration The process of passing a liquid through a biological filter, thus permitting contact with attached growth or fixed zoogleal films attached to the media that adsorb and absorb fine suspended, colloidal, and dissolved solids and release end products of biochemical oxidation.
biological growth The activity and growth of any and all living organisms.
biological magnification The step-by-step concentration of substances in successive levels of the food chain; commonly reported only for harmful substances.
biological oxidation Decomposition of complex organic materials by microorganisms in the presence of atoms or molecules that accept electrons during biological metabolism. Occurs in self-purification of water bodies and in aerobic and anaerobic wastewater treatment processes.
biological oxygen demand (bod) More correctly, the biochemical oxygen demand. An indirect measure of the concentration of biologically degradable material present in organic wastes. It usually reflects the amount of oxygen consumed in five days by biological oxidation of organic matter.
biological process Process characteristic of, or resulting from, the activities of living organisms.
biological product Any virus, therapeutic serum, toxin, antitoxin, vaccine, blood, blood component or derivative, allergenic product, or analogous product, or arsphenamine or its derivatives (or any other trivalent organic arsenic compound), applicable to the prevention, treatment, or cure of diseases or injuries in man.
biological productivity See productivity.
biological purification
biological reactor The basins, tanks, or media, designed to maintain a quantity of biomass, such as in a wastewater treatment plant, where the principal biological treatment occurs.
biological response modifier Generic term for hormones, neuroactive compounds, and immunoreactive compounds that act at the cellular level; many are possible candidates for biotechnological production.
biologicals Vaccines, cultures, and other preparations made from living organisms and their products, intended for use in diagnosing, immunizing, or treating humans or animals or in related research.
biological stability See stability.
biological treatment A treatment technology that uses a biomass, including bacteria, to process organic waste through biodegradation.
biological wastewater treatment
biologic transmission The indirect vector-borne transmission of an infectious agent in which the agent undergoes biologic changes within the vector before being transmitted to a new host.
biomagnification A process that results in the accumulation of a chemical in an organism at higher levels than are found in its food. It occurs when a chemical becomes more and more concentrated as it moves up through a food chain. At the top of the food chain an animal, through its regular diet, may accumulate a much greater concentration of chemical than was present in organism lower in the food chain.
biomass 1) The total weight of matter (living and dead) incorporated into a quantity of organisms. 2) The amount of living matter in a given habitat that may be supported through an established ecosystem.
biome Any of the major terrestrial ecosystems of the world, such as tundra, deciduous forest, desert, taiga, etc.
biomonitoring 1) The use of living organisms to test the suitability of effluents for discharge into receiving waters and to test the quality of such waters downstream from the discharge. 2) analysis of blood, urine, tissues, etc. to measure chemical exposure in humans.
bioreactor A vessel in which the central reactions of a biotechnological process takes place. Typically the vessel contains microbes grown under controlled conditions of temperature, aeration, mixing, acidity and sterility. See biological treatment.
bioremediation A process of adding nutrients to groundwater to speed up the natural process in which bacteria biodegrade gasoline into harmless compounds.
biosensors The powerful recognition systems of biological chemicals (enzymes, antibodies, dna) are coupled to microelectronics to enable rapid, accurate low- level detection of such substances as sugars and proteins (such as hormones) in body fluids, pollutants in water and gases in air.
biosolids Sewage sludge that has been treated and managed in order to comply with state and federal standards required for beneficial use.
biosphere That portion of the solid and liquid earth and its atmosphere where living organisms can be and are sustained.
biostabilizer A machine that converts solid waste into compost by grinding and aeration.
biota All the named or nameable organisms of an area; the fauna and flora of a region.
biotechnology Techniques that use living organisms or parts of organisms to produce a variety of products (from medicines to industrial enzymes) to improve plants or animals or to develop microorganisms to remove toxics from bodies of water, or act as pesticides.
biotic Of or related to life.
biotic community See community.
biotic influence
biotic potential The inherent ability of members of a population to grow in numbers within a given time and under stated environmental conditions.
biotic pyramid The set of all food chains or hierarchic arrangements of organisms as eaters and eaten in a prescribed area when tabulated by numbers or biomasses; usually takes a pyramidal form.
biotic succession See succession.
biotope A segment, usually a small segment, of a habitat.
biotransformation Conversion of a substance into other compounds by organisms; includes bioremediation.
biotype A genetically homogenous population composed only of closely similar individuals; a genotypic race or group of organisms.
bit, binary digit The smallest unit of information a computer can use. A bit is represented as a "0" or a "1" (also "on" or "off"). A group of eight bits is called a byte. Bits are often used to measure the speed of digital transmission systems.
bivalve A gastropod having a shell composed of two valves, e.g., a clam.
black ice 1)Transparent ice formed in rivers and lakes. 2) Ice which forms on horizontal surfaces, such as roads, which is nearly transparent due to the absence of trapped air bubbles.
blackwater Water that contains animal, human, or food waste.
blank A bottle containing only dilution water or distilled water; the sample being tested is not added. Tests are frequently run on a sample and a blank and the differences are compared.
blast effect A pulse of air in which pressure increases sharply at the front, accompanied by winds, propagated from an explosion.
blending A method to reduce contaminants in drinking water by mixing contaminated water with clean water from another source to lower the contaminant concentration. Water blended for nitrate reduction is not safe for infants, but is acceptable for livestock and healthy adults.
block A quantity of water for which a price per unit of water (or billing rate) is established.
block-rate pricing Method of charging on the basis of the volume of water used.
blood products Any product derived from human blood, including but not limited to blood plasma, platelets, red or white corpuscles, and derived licensed products such as interferon.
bloom 1) To flower. 2) Of algae, to appear or occur suddenly or in large quantity or degree. See algal bloom.
blowdown The removal of accumulated solids in boilers to prevent plugging of boiler tubes and steam lines. In cooling towers, blowdown is used to reduce the amount of dissolved salts in the recirculating cooling water.
blowdown apparatus
blower Equipment that develops and transfers compressed air.
blue baby syndrome A disease that affects the oxygen carrying capacity of infant's blood, usually resulting from the consumption of high levels of NO3. Also know as methemoglobinemia.
BMP Best management practices.
Board The State Board of Health.
BOD See biochemical oxygen demand.
BOD5 Five-day biochemical oxygen demand; the oxygen demand exerted after five days of a BOD test. See Biochemical Oxygen Demand.
BOD load The BOD content, usually expressed in pounds per unit of time, of wastewater passing into or through a wastewater treatment system.
bog A quagmire or wet, spongy ground; composed primarily of dead plant tissues (peat), principally mosses. Often a filled in lake.
boiling point The temperature at which a component's vapor pressure equals atmospheric pressure. Boiling point is a relative indicator of volatility and generally increases with increasing molecular weight.
boil-water advisory A statement to the public advising persons to boil tap water before drinking it.
boiling water reactor (BWR) A type of reactor system which allows water to boil directly in the reactor core to produce steam for the turbine generator.
bona fide Literally “in good faith.” A bona fide document is a genuine one.
bond A written promise to pay a certain sum of money in the event agreed upon conditions are not met.
bonnet The cover on a gate valve.
book value
boom 1) A floating device used to contain oil on a water body. 2) A piece of equipment used to apply pesticides from a tractor or truck.
border ice An ice sheet in the form of a long border attached to the bank or shore. Also known as shore ice.
bore Same as tidal bore.
borehole, geophysical A general term that encompasses all techniques in which a sensing device is lowered into a borehole for the purpose of characterizing the associated geologic formations and their fluids. The results can be interpreted to determine lithology, geometry, resistivity, bulk density, porosity, permeability, and moisture content.
borrow pit A pit or excavation area used for gathering earth materials (borrow)such as sand or gravel.
botanical pesticide A pesticide whose active ingredient is a plant-produced chemical such as nicotine or strychnine. Also called a plant-derived pesticide.
bottom ash The non-airborne combustion residue from burning pulverized coal in a boiler; the material which falls to the bottom of the boiler and is removed mechanically; a concentration of the non-combustible materials, which may include toxics.
bottom land hardwoods Forested freshwater wetlands adjacent to rivers in the southeastern United States, especially valuable for wildlife breeding, nesting and habitat.
bottomland hardwood forests Forested, periodically flooded wetlands found along rivers.
bottom ventilation
botulism Food poisoning due to the presence of a powerful exotoxin developed from botulinum bacteria.
boulder Any loose rock (sediment) larger than 256 millimeters (10 inches).
boundary layer In general, a layer of air adjacent to a bounding surface.
brackish Describing a mix of fresh and salt waters having a total dissolved solids content exceeding a certain value (1,000 mg/L). See brackish water.
brackish ice Ice formed from brackish water.
brackish marsh A marsh occurring where salinity ranges from 3-15 parts per thousand; dominated by wiregrass.
brackish water All water with more than 1,000 mg/L of dissolved solids.
braided stream A stream characterized by successive division and rejoining of streamflow with accompanying islands. A braided stream is composed of anabranches.
brake horsepower 1) The horsepower required at the exterior driving end of a pump shaft (input to a pump). 2) The energy provided by a motor or other power source.
brash ice Accumulation of floating ice made up of fragments not more than about 6 feet (2 meters) across; the wreckage of other forms of ice.
breach The failed opening in a dam.
break-bulk cargo Term used to describe cargo that is transported in individual units, i.e., sacks, boxes, bags, or cartons which are not containerized. Also refers to loose (unbound) items such as activated carbon.
breakdown product A compound derived by chemical, biological, or physical action upon a pesticide. The breakdown is a natural process which may result in a more toxic or a less toxic compound and a more persistent or less persistent compound.
breakpoint chlorination Addition of chlorine to water until the chlorine demand has been satisfied. At this point, further additions of chlorine will result in a free residual chlorine that is directly proportional to the amount of chlorine added beyond the breakpoint.
breakthrough A crack or break in a filter bed allowing the passage of floc or particulate matter through a filter, causing an increase in filter effluent turbidity. A breakthrough can occur: 1) when a filter is first placed in service, 20 when the effluent valve suddenly opens or closes, and 3) during periods of excessive head loss through the filter (including when the filter is exposed to negative heads).
breakthrough curve A plot of relative concentration versus time, where relative concentration is defined as C/Co with C as the concentration at a point in the ground-water flow domain, and Co as the source concentration.
breakup The time when a river whose surface has been frozen from bank to bank for a significant portion of its length begins to change to an open water flow condition. The event is signaled by the breaking of the ice and often associated with ice jams and flooding.
breccia Rock made up of angular fragments of other rocks held together by mineral cement or a fine-grained matrix.
brine 1) Salt content equivalent to or exceeding that of seawater (10 parts per thousand) 2) An expression sometimes used to describe the concentrate from a membrane filtration process.
brine mud Waste material, often associated with well-drilling or mining, composed of mineral salts or other inorganic compounds.
brinelling Tiny indentations (dents), high on the shoulder of the bearing race or bearing. A type of bearing failure.
British Thermal Unit (Btu) The quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at 39 degrees F; used as the standard for the comparison of heating values of fuels.
broadcast application The spreading of material over an entire area through aerial discharge of a mass of that material over some distance.
browse Shoots, twigs, and leaves of trees and shrubs eaten by cattle or other large herbivores, such as deer.
browser Software that allows you to "surf " the Internet. Netscape, Mosaic, and Internet Explorer are examples of Web browsers. A browser provides an easy to use interface for accessing the information on the World Wide Web.
bubble A system under which existing emissions sources can propose alternate means to comply with a set of emissions limitations; under the bubble concept, sources can control more than required at one emission point where control costs are relatively low in return for a comparable relaxation of controls at a second emission point where costs are higher.
bubble policy (See: emissions trading.)
bubble radius The maximum radial distance away from a biosparging well where the effects of sparging are observable. Analogous to radius of influence of an air sparging well.
bubbler gage A water stage recording device capable of being attached to a LARC for data automation purposes.
bubbler tide gauge Same as gas purged pressure gauge.
budding A form of asexual reproduction. The “mother” cell divides into two unequal parts. The smaller part, the “bud,” is a new cell and an outgrowth from the larger cell.
budget (water-use) An accounting of total water use or projected water use for a given location or activity.
budget year The fiscal year for which appropriations are being requested.
buffer 1) A solution or liquid whose chemical makeup neutralizes acids or bases without a great change in pH. 2) A distance established between an activity and a boundary within which access and use restrictions are established to protect public health and water quality. See buffer strips.
buffer capacity A measure of the capacity of a solution or liquid to neutralize acids or bases. This is a measure of the capacity of water for offering a resistance to changes in pH.
buffer solution
buffer strips Continuous lengths of buffer areas, including strips of grass or other close-f\growing vegetation that separate a waterway from an intensive land use area; also referred to as filter strips, vegetated filter strips, and grassed buffers.
building cooling load The hourly amount of heat that must be removed from a building to maintain indoor comfort (measured in British Thermal Units BTUs).
buildup The vertical distance the water table or potentiometric surface is raised, or the increase of the pressure head due to the addition of water.
bulk density The mass of dry matter including air space per unit volume of material.
bulking A condition found in the activated sludge treatment process when the flocculated biomass becomes buoyant and does not settle properly in a clarifier.
bulk sample A small portion (usually thumbnail size) of a suspect asbestos containing building material collected by an asbestos inspector for laboratory analysis to determine asbestos content.
bulking sludge Contents of an activated sludge bioreactor that settle poorly because of low-density biomass, such as filamentous bacteria.
bulky waste Large items of waste materials, such as appliances, furniture, large auto parts, trees, stumps.
buoyant Will rise and float in a liquid or gas.
burial ground A disposal site for radioactive waste materials that uses earth or water as a shield.
buried channel
burden of proof The necessity or duty of proving a fact or facts in dispute on an issue. If the evidence produced by the party having the burden of proof is insufficient, the court will rule against the party.
business process engineering A systematic disciplined improvement approach that critically examines, rethinks, and redesigns mission-delivery processes and subprocesses for radical performance gains in meeting customer and stakeholder needs and expectations.
butterfly gate
butterfly valve A shut-off valve usually found in larger pipe sizes (4 inches or greater). This type of valve can be used for non-critical flow control.
buttress dam A dam comprised of reinforced masonry or stonework built against concrete usually in the form of flat decks or multiple arches. Buttress dams require about 60 percent less concrete than gravity dams, but the increased form work and reinforcement steel required usually offset the savings in concrete. Many were built in the 1930s when the ratio of labor cost to materials was comparatively low. However, this type of construction is not competitive with other types of dams when labor costs are high.
bw. Body weight.
by-product Material, other than the principal product, generated as a consequence of an industrial process.