NGWA EXAM QUESTIONS AND
DETAILED CORRECT ANSWERS 100%
National Groundwater Association
Water well defined
Drilled, cored, bored, washed, dug, driven, jetted excavation, constructed for extracting
groundwater.
Cable tool drill string
Socket, jars, stem, and drill bit.
Drill String
Entire column of string or drill pipe, drill collars, and accessories that transmit fluid and/or
rotational power from Kelly(top head drive) to the drill collars and bit.
Rotary Drill string
Drill bit, Drill collar (stabilizer), Drill pipe, Kelly (top head)
Porosity
The percentage of void spaces or holes in geologic formation. The amount of connected pore
spaces
Barite
barium sulfate (BaSO4), a mineral used to increase the weight of drilling fluid (mud); its specific
gravity is 4.2
Air Rotary Drilling
a method of rotary drilling that uses compressed air as the circulating medium; compressed air
at high uphole velocity removes the cuttings
Surfactants
Improve flushing of cuttings from bit. Used in air-based drilling to produce foam during well
drilling, also well development to disaggregate clays
, 2.31
Unit of energy constant to overcome gravity. Head calculation 2.31 X 40psi = 92.4' of lift. 600' /
2.31 = 260psi
Well Development
a procedure to facilitate the removal of fine solids and materials from the water-bearing zone of
a water well to optimize production
Well Development Methods
Chemical, Over pumping, Rawhiding (Washing and backwashing), Mechanical Surging, Jetting,
Air surging.
Over Pumping
Well Development method; involves pumping well at a much higher rate than it will be pumped
during well evacuation or sampling.
Rawhiding (washing and back washing)
Well Development method, involves pumping water to the top of the well then allowing it to
flow back through the intake of the pump, breaking up the bridge of sediments only around the
pump intake.
Mechanical Surging
Well Development method, involves attaching a surging block to the drill rod that fits well inside
diameter, then dropping the block rapidly, forcing the water back up into the surrounding
aquifer. In the recovery stroke water is lifted back into the well allowing fine sediments to flow
from the aquifer.
Jetting
Well Development method, involves attaching a surging block like tool with jetting nozzles, then
with an external water pressure supply jet the water back into the well screen with in the well
where it is most needed.
Air Surging
Well Development method, involves injecting air into the borehole such that aerated slugs of
water are lifted irregularly out the top of the well casing. Air pressure may be cycled on and off
to create a surging action desirable in well development. Sufficient air pressure will result in a
continuous flow of aerated water out the top of the well, removing sediment and fine particles
from the borehole.
DETAILED CORRECT ANSWERS 100%
National Groundwater Association
Water well defined
Drilled, cored, bored, washed, dug, driven, jetted excavation, constructed for extracting
groundwater.
Cable tool drill string
Socket, jars, stem, and drill bit.
Drill String
Entire column of string or drill pipe, drill collars, and accessories that transmit fluid and/or
rotational power from Kelly(top head drive) to the drill collars and bit.
Rotary Drill string
Drill bit, Drill collar (stabilizer), Drill pipe, Kelly (top head)
Porosity
The percentage of void spaces or holes in geologic formation. The amount of connected pore
spaces
Barite
barium sulfate (BaSO4), a mineral used to increase the weight of drilling fluid (mud); its specific
gravity is 4.2
Air Rotary Drilling
a method of rotary drilling that uses compressed air as the circulating medium; compressed air
at high uphole velocity removes the cuttings
Surfactants
Improve flushing of cuttings from bit. Used in air-based drilling to produce foam during well
drilling, also well development to disaggregate clays
, 2.31
Unit of energy constant to overcome gravity. Head calculation 2.31 X 40psi = 92.4' of lift. 600' /
2.31 = 260psi
Well Development
a procedure to facilitate the removal of fine solids and materials from the water-bearing zone of
a water well to optimize production
Well Development Methods
Chemical, Over pumping, Rawhiding (Washing and backwashing), Mechanical Surging, Jetting,
Air surging.
Over Pumping
Well Development method; involves pumping well at a much higher rate than it will be pumped
during well evacuation or sampling.
Rawhiding (washing and back washing)
Well Development method, involves pumping water to the top of the well then allowing it to
flow back through the intake of the pump, breaking up the bridge of sediments only around the
pump intake.
Mechanical Surging
Well Development method, involves attaching a surging block to the drill rod that fits well inside
diameter, then dropping the block rapidly, forcing the water back up into the surrounding
aquifer. In the recovery stroke water is lifted back into the well allowing fine sediments to flow
from the aquifer.
Jetting
Well Development method, involves attaching a surging block like tool with jetting nozzles, then
with an external water pressure supply jet the water back into the well screen with in the well
where it is most needed.
Air Surging
Well Development method, involves injecting air into the borehole such that aerated slugs of
water are lifted irregularly out the top of the well casing. Air pressure may be cycled on and off
to create a surging action desirable in well development. Sufficient air pressure will result in a
continuous flow of aerated water out the top of the well, removing sediment and fine particles
from the borehole.
