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Contaminated and Hazardous Waste Site Management

Glossary B


Backfill: Material used temporarily during construction (e.g. of wells) or permanently during mining to replace the material being removed.

Background Correction: A technique to compensate for variable background contribution to the instrument signal in the determination of trace elements.

Background Level: The amount of a substance typically found in the air, water, or soil from non-site related activities.

Bacteria: Unicellular microorganisms that exist either as free-living organisms or as parasites and have a broad range of biochemical, and often pathogenic, properties. Bacteria can be grouped by form into five general categories: cocci (spherical), bacilli (rod-shaped), vibrio (curved rod-shaped), spirilla (spiral), and filamentous (thread-like).

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.

Bail Test: A test carried out to determine in-situ hydraulic conductivity by instantaneously removing a known water quantity from a well and measuring the resulting well recovery. Used for single wells in low to moderate hydraulic conductivity formations. Also called rising head test.

Bailer: A long, narrow tube with an open top and a check valve at the bottom. It is used to remove water and/or cuttings from a borehole or well.

Ball Valve: A valve regulated by the position of a free-floating ball that moves in response to fluid or mechanical pressure.

Bar Graph Spectrum: A plot of the mass-to-charge ratio (m/e) versus relative intensity of the ion current.

Base Flow: The sustained low flow in a stream. Generally base flow is the inflow of groundwater to the stream.

Batch: A group of samples prepared at the same time in the same location using the same method.

Bedding Plane: A planar or nearly planar surface, within a mass of stratified rock layers, that visibly separates each successive layer.

Bedrock: A general term referring to rock that underlies unconsolidated material.

Bentonite: A hydrous aluminium silicate clay mineral which is used to provide a seal between well casing and the borehole. Also, it is sometimes added to drilling fluid to increase its viscosity.

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.

Bioaccumulate: The process by which some contaminants or toxic chemicals gradually collect and increase in concentration in living tissue, such as in plants, fish, or people, as they breath contaminated air, drink contaminated water, or eat contaminated food.

Bias, Biasing: A systematic difference between the true and measured value.

Bioassay: A method used to determine the toxicity of specific chemical contaminants. A number of individuals of a sensitive species are placed in water containing specific concentrations of the contaminant for a specified period of time.

Bioaugmentation: The introduction of cultured microorganisms into 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.

Biocide: A substance capable of destroying (killing) living organisms.

Biodegradability (or biodegradation potential): The relative ease with which petroleum hydrocarbons will degrade as the result of biological metabolism. Although virtually all petroleum hydrocarbons are biodegradable, biodegradability is highly variable and dependent somewhat on the type of hydrocarbon. In general, biodegradability increases with increasing solubility; solubility is inversely proportional to molecular weight.

Biodegradation: A subset of biotransformation, it is the biologically mediated conversion of a
compound to more simple products.

Biological Activity: In the subsurface, usually the action of microorganisms, especially bacteria.

Biological Treatment: The use of bacteria or other microbial organisms to break down toxic
organic materials into carbon dioxide and water. Biomass: the amount of living matter in a given area or volume.

Bioremediation: A cleanup process using naturally occurring or specially cultivated microorganisms to digest contaminants and break them down into non-hazardous components.

Bit: A cutting tool attached to the bottom of the drill stem. Its design varies according to the type of drilling equipment used; based on the type of formation which is to be drilled.

Bladder Pump: The pump consists of a flexible bladder within a rigid cylindrical frame. The lower end of the bladder is connected to the intake port and the upper end is connected to the sample line. A gas line leads from ground surface to the space between the bladder and frame. After filling under hydrostatic pressure, application of gas pressure causes the bladder to collapse, forcing the sample to ground surface through the sample line.

Blanks: Samples that are the same as the samples of interest except in some respect whose influence on the samples is being evaluated. For example, a trip blank is transported just like actual samples, but it doesn't contain the chemicals to be analyzed. It evaluates the possibility that a chemical could seep into the samples during transportation to the laboratory.

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.

Borehole: A hole drilled or bored into the earth, and into which casing, screen, etc. may be installed to construct a well.

Borrow Pit: An excavated area where soil, sand, or gravel has been dug up for use elsewhere.

Boundary Condition: A mathematical model must be defined within a physical domain; the idealized flow or transport behaviour along the domain boundaries form the boundary conditions of the model.

Bouguer Correction: The process of correcting gravity data for the mass of the rock between a given station and its reference (base) station. Application of the Bouguer correction to the data set, as well as corrections for latitude, topography, meter drift and elevation, yields the Bouguer anomaly.

Breakthrough Curve: A plot of column effluent concentration over time. In the field, monitoring a well produces a breakthrough curve for a column from a source to the well screen.

Breccia: Fragments of rock, generally angular in a fine grained matrix, or a matrix of cementing material. Breccias include tectonic brecccias, clastic brecccias and volcanic breccias.

Brecciated Zone: A zone converted into a breccia.

BTEX: Abbreviation for benzene, toluene, ethylbenzene and xylenes which are the most soluble compounds of gasoline.

BTU (British Thermal Unit): The quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit at 39?F; used as the standard for comparison of heating values of fuels.

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.

Buffer: A substance (or mixture of substances) capable of neutralizing both acids and bases when added to a solution, but without significantly changing its original acidity or alkalinity.

Bulk Density: The amount of mass of a soil per unit volume of soil; where mass is measured after all water has been extracted and total volume includes the volume of the soil itself and the volume of air space (voids) between the soil grains.

Bulk Mass Density: The weight of a material divided by its volume (including the volume of its pore spaces). Specifically, it refers to the weight per unit volume of a soil mass that has been oven-dried to a constant weight at 105oC.

Bulk Modulus: A modulus of elasticity, relating change in volume to the hydrostatic state of stress. It is the reciprocal of compressibility.

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.

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