absorption
The process by which substances in gaseous, liquid, or solid form dissolve or mix with other substances.
adsorption
The attraction and adhesion of ions from an aqueous solution to the surface of solids.
air sparging
The process of injection of air below the water table to strip volatile contaminants from the saturated
zone.
air stripping
A remediation process for removing VOCs from groundwater by aeration.
alluvial
Pertaining to, or composed of, alluvium or deposited by a stream or running water.
Alluvium
A general term for clay, silt, sand and gravel, or similar unconsolidated material deposited by a river
as a sorted or semi-sorted sediment in the bed of the river or on its floodplain or delta.
analytical model
A mathematical model that provides an exact or approximate solution of a differential equation (and the
associated initial and boundary conditions) for subsurface water movement or transport.
anisotropy
The conditions under which one or more of the hydraulic properties of an aquifer vary with direction.
(See also isotropy.)
aquiclude
A geologic formation which may contain water (sometimes in appreciable quantities), but is incapable of
transmitting significant quantities under ordinary field conditions.
aquifer
A geologic formation, group of formations or part of a formation that contains saturated permeable
material that yields sufficient, economical quantities of groundwater.
aquifer system
Two or more permeable units separated at least locally by confining units that impede groundwater
movement but do not greatly affect the regional hydraulic continuity of the system.
aquifer test
See pumping test.
aquifuge
An impervious formation which neither contains nor transmits water.
aquitard
A semi-pervious geologic formation which can store water but transmits water at a overflow rate compared
to the aquifer.
area of influence
Area surrounding a pumping or recharging wen within which the water table or potentiometric surface has
been changed due to the well’s pumping or recharge. Also called zone of influence.
artesian aquifer
Commonly used expression, generally synonymous with (but less favored term than)confined aquifer. The
term “artesian” takes its name from the basin of Artois in France.
artesian well
A well deriving its water from a confined (“artesian”) aquifer.
artificial recharge
The process by which water can be injected or added to an aquifer. Dug basins, wells, or the spread of
water across the land surface are all means of artificial recharge.
attenuation
The process of diminishing contaminant concentrations in groundwater, due to filtration,biodegradation,
dilution, sorption, volatilization, and other processes.
backreamer
A tool attached to the end of the drill string and pulled through the bore to enlarge the hole and mix
the cuttings with the drilling fluid.
bailer
A device used to withdraw a water sample from a small-diameter well or piezometer. It is typically a
piece of pipe having a check valve in the bottom.
bail-down test
A type of slug test performed by using a bailer to remove a volume of water-from a small-diameter well.
baseflow
That part of a stream discharge not attributable to direct runoff from precipitation or snowmelt,
usually sustained by groundwater discharging into the stream.
bedrock
A general term for the rock formation, usually solid, that underlies soil or other unconsolidated
materials.
bentonite
An absorbent aluminum silicate clay formed from volcanic ash. When thoroughly mixed with water,
bentonite breaks down into small particles called platelets. The platelets plaster or shingle off the
wall of the hole and form a filter cake that cuts off the flow of water into the surrounding sand or
gravel.
bioaugmentation
Similar to bioremediation, but involving the introduction of organisms to affect cleanup.
biodegradation
A subset of biotransforination, it is the biologically mediated conversion of a compound to more simple
products.
bioremediation
A cleanup method involving the stimulation of naturally occurring organic substances in the soil.
bioventing
A process by which air is injected into the subsurface to stimulate biodegradation by microbes.
bore
1. A hole made in the ground by drilling or pushing.
2. The act of making a hole in the ground by drilling or pushing.
BORE-GEL
A single-sack boring fluid system, which consists of bentonite, polymer, and soda ash,specially
formulated by Baroid Drilling Fluids, Inc., for use in trenchless technology construction applications.
Processed from premium grade Wyoming sodium bentonite with an extra high yield, enhanced to provide
superior hole stabilizing properties and cuttings support with improved lubrication and torque
reduction.
box
The female thread portion of a drill pipe.
bubbling pressure
The pressure at which air enters saturated zone (or air entry value or threshold pressure).
build-up
The potentiometric surface (or the water table) rise in the vicinity of a’ recharge wen. It is the
vertical distance between the initial and the new potentiometric surface (or the water table in the case
of an unconfined aquifer) at a given point.
bulk density
The mass of a soil per unit bulk volume of soil; the mass is measured after all water has been extracted
and the volume includes the volume of the soil itself and the pore volume.
cable sonde
A probe or transmitter that operates with a wire attached to the drill rack for locating purposes.
calibration of models
Refinement of estimates of the input parameters and boundary conditions of a model until model results
match the field-observed data. Also known as “history matching.”
caliche
A geological formation often found in the Southwestern United States that can be as hard as rock but
more closely resembles very dry layered clay which becomes sticky when wet.
capillary form
Interfacial forces between immiscible fluid phases, resulting in pressure differences between the two
phases.
capillary fringe
The zone immediately above the water table within which the water is drawn by capillary forces (fluid is
under tension). The capillary fringe is saturated, and it is considered to be part of the unsaturated
zone.
carbonate
A sediment formed by the organic or inorganic precipitation from aqueous solution of carbonates of
calcium, magnesium, or iron.
carbonate rock
A rock consisting chiefly of carbonate minerals, such as limestone and dolomite.
Chinese Finger
A woven wire device used to pull product back through the bore. It is slipped over the outside diameter
of the product and attached to the drill string. The harder it is pulled, the tighter it gets.
clastic
Pertaining to a rock or sediment composed principally of broken fragments that are derived from
pre-existing rocks or minerals and that have been transported some, distance from their places of
origin.
coarse
The term used to denote sand and gravel. The use of bentonite in the drilling fluid is recommended when
boring in this type of soil conditions.
compactor
A reamer that enlarges the hole by compressing the soil as it is pulled through the bore.
concentration gradient
The change in concentration with distance across a fluid medium.
CON-DETO
A clear arnber liquid blend of water soluble anionic surfactant manufactured by Baroid Drilling Fluids,
Inc. It can be used in conjunction with Quik-Gelo® to aid in reducing the tendency of the hole-boring
tools being stuck by adhesive.
cone of depression
A depression in the groundwater table (or potentiometric surface) that has the shape of an inverted cone
and develops around a discharge well.
confined aquifer
An aquifer bounded above and below by confining layers of distinctly lower permeability than the aquifer
material and the one containing confined groundwater. When a well is installed in a confined aquifer,
the water level in the well rises above the top of the aquifer.
confining unit
A hydro geologic unit of relatively low hydraulic conductivity, bounding one or more aquifers. (See also
aquitard, aquifuge, and aquiclude.)
conservation solute
A non-reactive constituent that does not undergo chemical reaction during substance migration.
contaminant
Toxic substances found in soils and groundwater.
contamination
The degradation of natural water quality as a result of man’s activities. There is no implication of any
specific limits, since the degree of permissible contamination depends upon the intended end use of the
water.
cosolvency
The interaction of one or more organic contaminants that may cause them to behave differently than if
they were present alone in their pure form.
cuttings
Soil particles, also known as drilling spoils, created during the boring process..Use of the proper
drilling fluid will help to suspend the cuttings which reduces the risk of getting stuck while boring
and backreaming.
Darcy’s law
An empirically derived equation for the flow of fluids through porous media. It is based on the
assumptions that flow is laminar and inertia can be neglected, and states that the specific discharge,
q, is directly proportional to the hydraulic conductivity, K, and the hydraulic gradient, J.
darcy, unit
A unit of intrinsic permeability, k (I darcy = 9.87 x 10-9 cm2). The relationship between hydraulic
conductivity, K, and the permeability, k, is given as K = kpg/u where p is the fluid density, g is the
gravitational constant, and u is the dynamic viscosity.
deflection
The amount of flex applied to the drill stem while steering the head.
density
The mass of a substance per unit volume [ML-3] Units are pounds per cubic foot (Ib/ft3),kilograms per
cubic meter (kg/m3), or grams per cubic centimeter (g/cm3).
depth
Refers to the depth of the drill head during a bore.
desorption
See adsorption, which is the reverse process.
diffusion coefficient
See molecular diffusion.
discharge area
An area in which groundwater is discharged to the land surface, surface water, or atmosphere. An area in
which there are upward components of hydraulic head in the aquifer. Groundwater is flowing toward the
surface in a discharge area and may escape as a spring, seep, or base flow, or by evaporation and
transpiration.
dispersion
The spreading and mixing of chemical constituents in groundwater caused by diffusion and mixing (due to
microscopic variations in velocities within and between pores).
dispersion coefficient
A measure of the spreading of a flowing substance due to the nature of the porous medium(and specific
substance or fluid properties), with interconnected channels distributed at random in all directions.
Also the sum of the coefficients of mechanical dispersion and molecular diffusion in porous medium.
dispersivity
A property of a porous medium (and the specific substance of fluid) that determines the dispersion
characteristics of the contaminant in that medium by relating the components of pore velocity to the
dispersion coefficient.
distribution (partitioning) coefficient
Relates the quantity of a solute sorbed per unit weight of the solid phase and the quantity of the
solute dissolved in water per unit volume of water.
DNAPL
Dense Non Aqueous Phase Liquid. A liquid consisting of a solution of organic compounds (e.g.,
chlorinated hydrocarbons) and which is denser than water.
drainage basin
The land area from which surface runoff drains into a stream.
drawdown
A lowering of the water table of an unconfined aquifer or the potentiometric surface of a confined
aquifer caused by pumping of groundwater from wells. The vertical distance between the original water
level and the new water level.
dry hole
If not enough drilling fluid is used, a dry hole occurs and the product becomes lodged in the ground.
duckbill
The drilling bit that attaches to the front of the boring head. It mounts to the head at an angle and
also is bent. This angle is what provides the steering capability while pushing the drill pipe.
effective grain size
The grain size corresponding to the 10% finer by weight on the grain-size distribution curve.
effective porosity
The interconnected pore space through which fluids can pass, expressed as a percent of bulk volume. Part
of the total porosity will be occupied by static fluid being held to mineral surface by surface tension,
so effective porosity will be less than total porosity.
effluent stream
See gaining stream.
entrance pit
The area where the drill pipe enters the ground after the drill machine is set up.
entry angle
The angle at which the drill head enters the ground or the degree that the rack is set at.
EPA
The Environmental Protection Agency. The federal authority responsible for enforcing the various laws
dealing with environmental standards.
equipotential line
A line in a two-dimensional groundwater flow field along which the total hydraulic head(the groundwater
potential) is constant.
evapotranspiration, actual
The evaporation that actually occurred under given climatic and soil-moisture conditions.
evapotranspiration, potential
The evaporation that would occur under given conditions if there were unlimited soil moisture.
exit pit
The area where the drill pipe exits the ground and the service lines are pulled back in.
extraction well
A discharge well used to remove groundwater or air.
EZ-MUD®
A premium grade, high molecular weight PUPA polymer manufactured by Baroid Company. When this is added
to bentonite in the drilling fluid, it provides extended high viscosity and gel strength. It also lowers
the filtration rate and increases lubrication. It is an excellent shale/clay stabilizer which minimizes
swelling.
Fick’s Law
The mass flux due to the molecular diffusion is proportional to the concentration gradient and the
diffusion coefficient.
field capacity
The amount of moisture remaining in the soil after an extended period of gravity drainage without
additional supply of water at the soil surface.
filter cake
The zone where the bentonite platelets plaster or shingle off the wall of the hole.
filtrate
The water portion of the drilling fluid that seeps through the filter cake.
fines
Term used to denote clay and shale soils. The use of polymer is recommended in these soil conditions to
reduce swelling while at the same time improving lubrication and torque reduction.
flow
When the drilling fluid moves or runs smoothly with unbroken continuity through the entire length of the
bore.
flowline or pathline
The general path that a particle of water follows under laminar flow conditions., Flow lines are
perpendicular to equipotential lines in an isotropic aquifer.
flow model
A digital computer model that calculates a hydraulic head field for the modeling domain using numerical
methods to arrive at an approximate solution to the differential equation of groundwater flow.
flow, steady
A characteristic of a flow system, where the magnitude and direction of specific discharge are constant
in time at any point. If the specific discharge has the same magnitude and direction at any point, the
flow is uniform.
flow, unsteady (transient)
A characteristic of a flow system where the magnitude and/or direction of the specific
discharge changes with time.
forged upset
The area at each end of a FIRESTICK drill stem where it tapers to a larger diameter. This larger
diameter is achieved by heating the ends of the rod to temperatures in excess of 2000º F and striking it
with tremendous force in a die set. To achieve this, the metal has to start out 3′ longer than the
desired finished length of the drill stem.
frac out
In certain conditions, the drilling fluid can build tremendous pressure in the bore. If the pressure
becomes great enough, the ground will fracture to the surface. The drilling fluid escapes the bore
through this rupture, and the pressure is relieved.
fracture
A general term for any break in a rock, which includes cracks, joints and faults.
fracture trace
Visible on aerial photographs, fracture traces are natural linear-drainage, soil-tonal, and topographic
alignments that are probably the surface manifestation of underlying zones of fractures.
front locate point
The point in front of the drill head where the DIGITRAKTM locator goes from + to -. This point is also
referred to as the front negative locate point.
gaining stream
A stream or reach of a stream, the flow of which is being increased by inflow of groundwater. Also known
as an effluent stream.
gel strength
The ability of the drilling fluid to support and suspend the cuttings. The use of bentonite in the
drilling fluid greatly increases these characteristics.
geostatistics
A methodology for the analysis of spatially correlated data. The characteristic feature is in the use of
variograms or related techniques to quantify and model the spatial correlation structure. Also includes
various techniques such as kriging, which utilize spatial correlation models.
ghost
False signals received by the locator.
glacial drift
A general term for unconsolidated sediment transported by glaciers and deposited directly on land or in
the sea.
glacial outwash
Well-sorted sand, or sand and gravel, deposited by the meltdown from a glacier.
glacial till
A glacial deposit composed of mostly unsorted sand, silt, clay, and boulders and laid down directly by
the melting ice.
gravitational head
Component of total hydraulic head related to the vertical position of a given mass of water relative to
an arbitrary datum.
gravitational water
Water that moves into, through, or out of a soil or rock mass under the influence of gravity.
ground stake
A long copper rod with a T handle and auger bit that is screwed into the ground and attached to the
boring machine to provide an additional path for electricity to flow in the event of an electrical
strike.
groundwater
The water contained in interconnected pores below the water table in an unconfined aquifer or in a
confined aquifer.
groundwater barrier
Rock or artificial material with a relatively low permeability that occurs (or is placed) below ground
surface, where it impedes the movement of groundwater and thus causes a pronounced difference in the
heads on opposite sides of the barrier.
groundwater basin
General term used to define a groundwater flow system that has defined boundaries and may include more
than one aquifer underlain by permeable materials that are capable of storing or furnishing a
significant water supply. The basin includes both the surface area and the permeable materials beneath
it.
groundwater divide
Ridge in the water table, or potentiometric surface, from which groundwater moves away at right angles
in both directions. Line of highest hydraulic head in the water table or potentiometric surface.
groundwater flow
The movement of water through openings in sediment and rock that occurs in the zone of saturation.
groundwater model
A simplified conceptual or mathematical image of a groundwater system, describing the feature essential
to the purpose for which the model was developed and including various assumptions pertinent to the
system. Mathematical groundwater models can include numerical and analytical models.
groundwater mound
Raised area in a water table or other potentiometric surface, created by groundwater recharge.
groundwater recharge
Process of water addition to the saturated zone, or the volume of water added by this process.
HAZMAT
A term used in the environmental industry to identify materials classified as hazardous by the EPA.
heat-treat
To treat metal by alternate heating and cooling in order to produce desired characteristics,such as
increased hardness; temper.
Henry’s Law
The relationship between the partial pressure of a compound and its equilibrium concentration in a
dilute aqueous solution through a constant of proportionality known as the Henry’s Law Constant.
heterogeneity
Characteristic of a medium in which material properties vary from point to point.
homogeneity
Characteristic of a medium in which material properties are identical throughout. Though heterogeneity
or nonunifonnity is the characteristic of most aquifers, assumed homogeneity, with some other additional
assumptions, allows use of analytical models as a valuable tool for approximate analyses of groundwater
movement.
hydra-lock
A situation that has been known to occur while pulling product through the bore. In this condition, the
bore acts as a huge hydraulic cylinder with the product string acting as a large hydraulic ram. The
drilling fluid stops flowing in the bore and pressure begins to build. The pressure continues to build
to the point where the boring machine can no longer pull the product string and you have a stuck
situation. Increased pullback pressure with decreased rotational pressure is an indication that
hydra-lock is occurring. This most often occurs in very tight soil conditions such as dry clay and can
sometimes be cured by digging a burp hole to relieve the pressure or by letting everything set for a
period of time while the pressure seeps past the product string.
hydraulic barrier
Modifications to a groundwater flow system that restrict or impede movement of contaminants.
hydraulic conductivity (K)
Proportionality constant relating hydraulic gradient to specific discharge, which, for an
isotropic medium and homogeneous fluid, equals the volume of water at the existing kinematic viscosity
that will move in unit time under a unit hydraulic gradient through a unit area measured at right angles
to the direction flow. The rate of flow of water in gallons per day through a cross section of one
square foot under a unit hydraulic gradient, at the prevailing temperature (gpd/ft2). In the standard
International System, the units are m3/day/m2 or m/day. A coefficient of proportionality describing the
rate at which water can move through a permeable medium. The density and kinematic viscosity of the
water must be considered in determining hydraulic conductivity.
hydraulic conductivity, effective
Rate of water flow through a porous medium that contains more than one fluid (such as water and air in
the unsaturated zone), which should be specified in terms of the fluid type,content and the existing
pressure.
hydraulic gradient (J)
Slope of a water table or potentiometric surface. More specifically, change in the hydraulic
head per unit of distance in the direction of the maximum rate of decrease. The difference in hydraulic
heads (hl-h2), divided by the distance
(L) along the flowpath: J= (hl-h2)/L.
hydraulic head (h)
Height above a datum plane (such as mean sea level) of the column of water that can be
supported by the hydraulic pressure at a given point in a groundwater system. Equal to the distance
between the water level in a well and the datum plane.
hydrodynamic dispersion
Spreading (at the macroscopic level) of the solute front during transport resulting from both mechanical
dispersion and molecular diffusion. The process by which groundwater containing a solute is diluted with
uncontaminated groundwater as it moves through an aquifer (see dispersion coefficient).
hydrogeologic
Those factors that deal with subsurface waters and related geologic aspects of surface waters.
hydrogeologic parameters
Numerical parameters that describe the hydro geologic characteristics of an aquifer such as porosity,
permeability, and transmissivity.
hydrogeologic pressure
Pressure exerted by the weight of water at any given point in a body of water at rest.
hydrogeologic unit
Any soil or rock unit or zone that has a distinct influence on the storage or movement of groundwater
because of its hydraulic properties.
immiscible
The chemical property where two or more liquids or phases do not readily dissolve in one another, such
as soil and water.
impermeability
Characteristic of geologic materials that limits their ability to transmit significant quantities of
water under the pressure gradients normally found in the subsurface environment.
impermeable layer
An area in the subsurface that has zero air flow. Limits the range of influence of extraction wells in
SVE systems.
infiltration
The downward entry of water into soil or rock.
infiltration rate
Rate at which soil or rock under specified conditions absorbs falling rain, melting snow, or surface
water; expressed in depth of water per unit time. Also, the maximum rate at which water can enter soil
or rock under specific conditions, including the presence of an excess of water; expressed in units of
velocity.
influent stream
See losing stream.
insitu
Latin term for “in the site,” used in environmental industry to describe the treatment of contaminants
without removal from their immediate location.
intrinsic permeability
Pertaining to the relative ease with which a porous medium can transmit a liquid under a hydraulic or
potential gradient. It is a property of the porous medium and is independent of the nature of the liquid
or the potential field.
isochron
A line connecting all points having the same time of travel for contaminant particles to move through
the saturated zone and reach a well.
isotropy
The condition in which the properties of interest (generally hydraulic properties of the aquifer) are
the same in all directions.
joint
Where the male and female threads of the drill stem come together.
kinematic viscosity
The ratio of dynamic viscosity to mass density. It is obtained by dividing dynamic viscosity by the
fluid density. Units of kinematic viscosity are square meters per second (M2/S).
klinkenberg effect
Gas slippage along pore walls. Darcy’s Law assumes that the velocity of a fluid at the pore wall surface
is zero.
kriging
A weight-moving-average interpolation method where the set of weights assigned to samples minimizes the
estimation variance, which is computed as a function of the variogram model and locations of the samples
relative to each other, and to the point or block being estimated.
laminar flow
Fluid flow in which the head loss is proportional to the first power of the velocity;synonymous with
streamline flow and viscous flow. Type of flow in which the fluid particles follow paths that are
smooth, straight, and parallel to the channel wars. In laminar flow, the viscosity of the fluid dampens
out turbulent motion.
leaching
Removal of materials in solution from rock, soil, or waste; dissolving out of soluble constituents from
a porous medium by percolation of water.
leakage
Flow of water from one hydrogeologic unit to another. This may be natural, as through a somewhat
permeable confining layer, or anthropogenic, as through an uncased well. It may also be the natural loss
of water from artificial structures, as a result of hydrostatic pressure.
leakage coefficient
The rate of flow across a unit (horizontal) area of a semi-pervious layer into (or out of) an aquifer
under one unit of head difference across this layer.
leaky aquifer
An artesian or water table aquifer that loses or gains water through adjacent semipermeable confining
units.
LNAPL
Lighter-than-water non aqueous phase liquid.
locator
The unit which picks up the signal from the drill head where the transmitter is housed.
losing stream
A stream or reach of a stream that is losing water by seepage into the ground. Also known as an influent
stream.
lubricity
Slick or slippery as in lubricate. Polymer in the drilling fluid will increase “lubricity” in the bore.
macropores
Relatively large pores in porous medium that allow the enhanced movement of liquid and gas.
make-up
The fitting together of the pin and box sections of the drill stem.
mats
Stainless steel wire mesh that is part of the strike alert and grounding system. The function of the
mats is to equalize the voltage around the machine in the event of an electrical strike.
matrix
Solid framework of a porous material or system.
mechanical dispersion
Process whereby solutes are mechanically mixed during advective transport, caused by the velocity
variations at the microscopic level; synonymous with hydraulic dispersion. The coefficient of mechanical
dispersion is the component of mass transport flux of solutes caused by velocity variations at the
microscopic level.
moisture content
See water content.
molecular diffusion
Process in which solutes are transported at the microscopic level due to variations in the solute
concentrations within the fluid phases.
monitoring well
A tube or pipe, open to the atmosphere at the top and to water at the bottom, usually along an interval
of slotted screen, used for taking groundwater samples.
mud
Drilling fluid.
NAPL
Non aqueous phase liquids.
negative locate
One of two points where a Digitrak locator reading goes from + to -.
nonpoint source
A source discharging pollutants into the environment that is not a single point.
nozzle
Located on the drill head to spray drilling fluid into the bore.
observation well
A well drilled in a selected location for the purpose of observing parameters such as waterl evels and
pressure changes. A non-pumping well used to observe the elevation of the water table or the
potentiometric surface. An observation well is generally of larger diameter than a piezometer and
typically is screened or slotted throughout the thickness of the aquifer.
organic carbon content
The amount of the organic carbon present in a soil. Organic chemicals in soil adsorb to soil organic
carbon and the amount of adsorption can be related to the soil organic carbon content.
partial penetration
When the intake portion of the well is less than the full thickness of the aquifer. A well constructed
in such a way that it draws water directly from a fractional part of the total thickness of the aquifer.
The fractional part may be located at the top, the bottom, or anywhere else in the aquifer.
partitioning
Chemical equilibrium condition where a chemical’s concentration is apportioned between two different
phases according to the partition coefficient, which is the ratio of a chemical’s concentration in one
phase to its concentration in the other phase.
peclet number
Relationship between the advective and diffusive components of solute transport;
expressed as the ratio of the product of the average interstitial velocity and the characteristic
length, divided by the coefficient of molecular diffusion. Small values indicate diffusion dominates;
large values indicate advection dominates.
perched aquifer
A special case of phreatic aquifer which occurs wherever an impervious (or semi-pervious)layer of
limited aerial extent is located between the water table of a phreatic aquifer and the ground surface.
perched water
Unconfined groundwater separated from an underlying main body of groundwater by an unsaturated zone.
percolation
Downward movement of water through the unsaturated zone; also defined as the downward flow of water in
saturated or nearly saturated porous media at hydraulic gradients of 1.0 or less. The act of water
seeping or filtering through the soil without a definite channel.
permeability coefficient
Rate of flow of water through a unit cross-sectional area under a unit hydraulic gradient at the
prevailing temperature (field permeability coefficient), or adjusted to 15 degrees C.
permeability, effective
Observed permeability of a porous medium to one fluid phase, under conditions of physical interaction
between the phase and other fluid phases present.
permeability, intrinsic
Relative ease with which a porous medium can transmit a fluid under a potential gradient,as a property
of the medium itself. Property of a medium expressing the relative ease with which fluids can pass
through it.
phreatic aquifer
See water table aquifer.
piezometer
A tube or pipe, open to the atmosphere at the top and to water at the bottom, and sealed along its
length, used to measure the hydraulic head in a geologic unit.
piezometer surface
See potentiometric surface.
pin
The male threads on the drill stem.
pitch
Measurement for the deviation from horizontal of the drill head.
platelet
A minute, disklike cytoplasmic body found in bentonite that plasters or shingles off the wall of the
hole to form a filter cake that cuts off the flow of water into the surrounding sand or gravel. When
broken down to its smallest dimension, there are enough platelets in a cubic inch of high-quality sodium
bentonite to cover 66 football fields.
point source
Any discernible, confined, or discrete conveyance from which pollutants are or may be discharged,
including (but not limited to) pipes, ditches, channels, tunnels, conduits,,wells,containers, rolling
stock, concentrated animal feeding operations, or vessels.
pollutant
Any solute or cause of change in physical properties that renders water unfit for a
given use.
pollution
When the contaminant concentration levels restrict the potential use of groundwater.
polymer
Any of numerous natural and synthetic compounds of usually high molecular weight consisting of up to
millions of repeated linked units, each a relatively light and simple molecule. Polymer, when used in
conjunction with bentonite in the drilling fluid, enhances viscosity and gel strength, lowers filtration
rate, and increases lubricity. The use of a polymer is recommended when boring in clay or shale.
pore space
Total space in an aquifer medium not occupied by solid soil or rock particles.
porosity
Ratio of the total volume of voids to the total volume of a porous medium. The percentage of the bulk
volume of a rock or soil that is occupied by interstices, whether isolated or connected. Porosity may be
primary, formed during deposition or cementation of the material, or secondary formed after deposition
or cementation, such as fractures.
positive locate
When locating with a Digitrak&, this is the point directly above the drill head where the locator
readout changes from + to -.
potable water
Suitable for human consumption as drinking water.
potentiometric surface
A surface that represents the level to which water will rise in wells penetrating a confined aquifer. If
the head varies significantly with depth in the aquifer, then there may be more than one potentiometric
surface. The water table is a particular potentiometric surface for an unconfined aquifer.
pothole
A hole dug to expose underground utilities crossing the proposed bore path.
pressure aquifer
Also known as confined aquifer. (See confined aquifer.)
pressure head
Hydrostatic pressure expressed as the height (above a measurement point) of a column of water that the
pressure can support.
pressure, static
Pressure exerted by a fluid at rest.
probe
An electronic device that fits inside the drill head and sends out a signal used to locate the head,
read pitch and roll, and determine depth.
PRPs
Potential responsible parties. Waste generators who are responsible for the ultimate fate of toxic
wastes. Includes property owners, industries, government agencies, etc. The current federal laws make
the PRPs liable in perpetuity for these wastes.
pH
The specific gravity of water.
public water supply system
System for provision to the public of piped water for human consumption. Such a system has at least 15
service connections or regularly serves at least 25 individuals daily or at least60 days out of the
year. The ten-n includes any collection, treatment, storage, and distribution facilities under control
of the operator of such system and used primarily in connection with the system, and any collection or
pretreatment storage facilities not under such control that are used primarily in connection with the
system.
pumping test
A test that is conducted to determine aquifer or well characteristics. A test made by pumping a
well for a period of time and observing the change in hydraulic head in the aquifer. A pumping test may
be used to determine the capacity of the well and the hydraulic characteristics of the aquifer. Also
called aquifer test.
PVC
Plastic pipe that can be used as well casing material.
quench
A step in the heat treating process to cool hot metal which causes it to harden. The most common quench
mediums are brine, water, oil, and air. The greatest hardness and strength for most materials are
obtained by brine or water quenching. However, this also produces the most distortion and cracking. Oil
or air quenching will produce less distortion and cracking but also less strength and hardness.
QUIK-GEL®
Highest-grade sodium bentonite manufactured by Baroid Drilling Fluids, Inc. This drilling fluid mix
develops a cost-effective low solids slurry with high viscosity, high gel strength,and controlled
filtration rate to provide formation and hole stabilization.
QUIK-TROL®
A white granular pure grade polymer manufactured by Baroid Drilling Fluids, Inc. When added to a
premixed bentonite slurry, it improves clay/shale stabilization and enhances all properties of a
bentonite slurry used in boring.
rack
The actual boring machine which includes drive head, controls, vise, etc.
radial flow
The flow of water in an aquifer toward a vertical well.
radius of influence
The radial distance from the center of a wellbore to the point where there is no lowering of the water
table or potentiometric surface (the edge of its cone of depression). The radial distance from an
extraction well that has adequate air flow for effective removal of contaminants when a vacuum is
applied to the extraction well.
range of influence
The area that can be remediated by an extraction well in an SVE system.
Raoult’s Law
A physical law which describes the relationship between the vapor pressure of a component over a
solution, the vapor pressure of the same component over pure liquid,and the mole fraction of the
component in the solution.
reamer
Any of various tools attached to the end of the drill string and pulled through the bore to enlarge the
hole and mix the cuttings with the drilling fluid.
rear locate point
The point behind the drill head where the readout on a Digitrak locator switches from + to -. This is
also called the rear negative locate point.
receiver
an electronic unit that receives information from the transmitter. This is also referred to as the
locator.
recharge
The addition of water to the zone of saturation; also, the amount of water added. Can be expressed as a
rate (i.e., in/yr) or a volume.
recharge area
An area in which there are downward components of hydraulic head in the aquifer. Infiltration moves
downward into the deeper parts of an aquifer in a recharge area.
recharge basin
A basin or pit excavated to provide a means of allowing water to soak into the ground at rates exceeding
those that would occur naturally.
recharge boundary
An aquifer system boundary that adds water to the aquifer. Streams and lakes are typical recharge
boundaries.
remedial construction
T’he business of implementing the methods for cleanup. Includes firms that specialize in underground
storage tank removal and soil vacuum extraction.
remediation
The methods of cleanup used for contaminated soils and groundwaters.
remote
An auxiliary electronic readout that displays information received from the receiver.
residual saturation
Saturation below which fluid drainage will not occur.
retardation
The movement of a solute through a geologic medium at a velocity less than that of the flowing
groundwater due to sorption or other removal of the solute.
Reynolds number
Dimensionless number expressing the ratio of inertial to viscous forces acting on the fluid,Re = pVd/u.
The number can be used to determine whether the flow is laminar or turbulent.
rockwell
The most commonly used method for determining the hardness of a metal.
rod
A section of drill stem.
rod wiper
A donut-shaped neoprene disk that fits around the drill stem to help clean it during the pullback.
roll
The rotational position of the drill head as it relates to a clock face.
RPM
The speed of the drill stem turning in the ground. It also relates to how fast the reamer turns.
runoff
That part of precipitation flowing to surface streams. The total amount of water flowing in a stream. It
includes overland flow, return flow, interflow, and baseflow.
safe yield
The amount of naturally occurring groundwater that can be withdrawn from an aquifer on a
sustained basis without impairing the native groundwater quality or lowering water levels.
saturation
The ratio of the volume of a single fluid in the pores to pore volume expressed as a percentage or a
fraction.
saturated zone
Portion of the subsurface environment in which all voids are ideally filled with water under pressure
greater than atmospheric. The zone in which the voids in the rock or soil are filled with water at a
pressure greater than atmospheric. The water table is the top of the saturated zone in an unconfined
aquifer.
seepage face
Whenever a phreatic surface approaches the downstream external boundary of a flow domain, it always
terminates on it at a point that is above the water table of the body of open water present outside the
flow domain. The segment of the boundary above the water table and below the phreatic surface is called
the seepage face.
semiconfined
An aquifer that has a “leaky” confining unit and displays characteristics of both confined and
unconfined aquifers. (See leaky aquifer.)
sewer probe
This transmitter is designed to bore sewer pipe by allowing the bore to be on grade. The probe works on
a 0. I% readout.
site characterization
T’he process of determining the geology, hydrology, type of contaminants and area of contamination. Done
by engineering and consulting firms.
skin effect
The damage to the permeability in the proximity of a well due to drilling fluids.
slug test
A test for estimating hydraulic conductivity of an aquifer in which a rapid water-level change is
produced in a piezometer or monitoring wen, usually by introducing or withdrawing a “slug” of water or a
weight. The rise or decline in the water level is monitored.
slurry wall
A subsurface wall constructed by digging a trench and backfilling it with a slurry and designed to
prevent groundwater flow.
soda ash
Sodium carbonate in powdery white form used to increase the PH level of hard water. This makes the
mixing of bentonite and polymers into the drill fluid much easier.
soil venting, soil vapor extraction, soil vacuum extraction, “SVE”
All describe the process of using extraction wells as a means to deliver a vacuum in the
subsurface, thereby pulling toxic vapors to the surface to be treated by an incineration,catalytic or
absorptive process.
solute transport
Net flux of solute through a hydrogeologic unit, controlled by the flow of subsurface -water and
transport mechanisms.
solute transport model
Mathematical model used to predict the movement of solutes (generally contaminants) in an aquifer
through time.
sonde
An electronic device that fits inside the drill head and transmits a signal used for locating purposes.
Also referred to as a transmitter or probe.
sorption
Processes that remove solutes from the fluid phase and concentrate them on the solid phase of a medium;
used to encompass absorption and adsorption.
sparging
A method of forcing VOCs from the saturated zone into the vadose zone by pushing air into the
groundwater.
specific capacity
The rate of discharge of water from the well divided by the drawdown within the well.
specific discharge
The volume of water flowing through a unit cross-sectional area of an aquifer.
specific drawdown
The drawdown within a well divided by the discharge rate of water from the well (inverse of specific
capacity).
specific gravity
The ratio of a substance’s density to the density of some standard substance, usually water.
specific retention
As water is being drained from the interstices of soil, after drainage has stopped, the volume of water
retained in an aquifer per unit area and unit drop of the water table.
specific storage
The amount of water