NGWA exam 80 complete solutions.

NGWA exam 80 complete solutions.
NGWA exam 80 complete solutions.
National Groundwater Assocation



Water well defined - ANSWERDrilled, cored, bored, washed, dug, driven, jetted excavation, constructed
for extracting groundwater.



Cable tool drill string - ANSWERSocket, jars, stem, and drill bit.



Drill String - ANSWEREntire 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 - ANSWERDrill bit, Drill collar (stabilizer), Drill pipe, Kelly (top head)



Porosity - ANSWERThe percentage of void spaces or holes in geologic formation. The amount of
connected pore spaces



Barite - ANSWERbarium sulfate (BaSO4), a mineral used to increase the weight of drilling fluid (mud); its
specific gravity is 4.2



Air Rotary Drilling - ANSWERa method of rotary drilling that uses compressed air as the circulating
medium; compressed air at high uphole velocity removes the cuttings



Surfactants - ANSWERImprove flushing of cuttings from bit. Used in air-based drilling to produce foam
during well drilling, also well development to disaggregate clays



2.31 - ANSWERUnit of energy constant to overcome gravity. Head calculation 2.31 X 40psi = 92.4' of lift.
600' / 2.31 = 260psi



Well Development - ANSWERa procedure to facilitate the removal of fine solids and materials from the
water-bearing zone of a water well to optimize production

, NGWA exam 80 complete solutions.

Well Development Methods - ANSWERChemical, Over pumping, Rawhiding (Washing and backwashing),
Mechanical Surging, Jetting, Air surging.



Over Pumping - ANSWERWell 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) - ANSWERWell 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 - ANSWERWell 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 - ANSWERWell 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 - ANSWERWell 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.



Chemical Well development - ANSWERWell Development method, involves using approved chemicals,
to breakup mud cakes, and flush out gelled muds, used in conjunction with other methods. Chemical
treatment can be used to break down drilling fluids, clays and polymers. Acids are often used for
improving the yield in limestone, dolomite and other calcium carbonate formations.



Cable Tool Bailors - ANSWER-Flat Bottom (Open bailer)

-Dart Valve (Valve Bailer)

-Sand Pump (double valve)