NGWA - STUDY QUESTIONS - GENERAL DRILLING EXAM (ANSWERED)
CORRECTLY TO SCORE A+/NEWEST UPDATE!!!
Question 1
What is the primary cause of artesian pressure in a groundwater system?
A) The rotation of the earth and thermal expansion
B) Gravity acting on the water column and the presence of confining beds
C) High-pressure pumps used in nearby industrial wells
D) The chemical reaction between water and limestone
E) Suction created by the vacuum of the atmosphere
Correct Answer: B) Gravity acting on the water column and the presence of confining beds
Rationale: Artesian pressure occurs when groundwater is "trapped" under pressure
between relatively impermeable layers called confining beds (such as clay or shale).
Because the recharge area (the intake) is at a higher elevation than the well location,
gravity pulls the water down, creating hydrostatic pressure. When a well penetrates the
upper confining bed, this pressure forces the water to rise above the level of the aquifer.
Question 2
Which of the following statements regarding the origin and characteristics of sedimentary rocks
is true?
A) Sandstones were originally igneous deposits that weathered into place.
B) Shales were originally clay beds that were compacted and cemented over time.
C) Limestones contain fossils because they were formed from cooling volcanic lava.
D) Sedimentary formations rarely reach depths greater than 100 feet.
E) Sedimentary rocks are the least common environment for finding groundwater.
Correct Answer: B) Shales were originally clay beds that were compacted and cemented
over time.
Rationale: Sedimentary rocks are formed by the accumulation of minerals or organic
particles. Sandstones originate from sand deposits (river, beach, or dunes); shales originate
from silt and clay; and limestones often form from organic remains on the floors of shallow
seas. These formations are significant in drilling because they can reach depths of a mile or
more and often serve as primary aquifers.
Question 3
True or False? Groundwater, similar to surface water, has a natural tendency to flow "downhill"
(from higher hydraulic head to lower).
A) True
B) False
Correct Answer: A) True
Rationale: Groundwater movement is governed by gravity and pressure (hydraulic head).
Water moves from areas of high potential energy (higher elevation or higher pressure) to
areas of lower potential energy. This means that groundwater generally follows the slope of
the water table or the pressure gradient, moving effectively "downhill" through the pores
of the rock.
, 2
Question 4
In which of the following geological formations would a driller be LEAST likely to find a
productive water source?
A) Sandstone
B) Unconsolidated gravel
C) Limestone with caverns
D) Solid Granite
E) Fractured metamorphic rock
Correct Answer: D) Solid Granite
Rationale: Granite is an igneous rock with very low primary porosity. Unless it is
significantly fractured or weathered (secondary porosity), it contains very little space for
water to store or move. Compared to porous sandstones or cavernous limestones, solid
granite is a very poor prospect for a high-yield water well.
Question 5
What percentage of the fresh water in the United States is located underground?
A) Less than 10%
B) Approximately 25%
C) Approximately 50%
D) More than 90%
E) Exactly 100%
Correct Answer: D) More than 90%
Rationale: While surface water in lakes and rivers is more visible, the vast majority of our
nation's available fresh water is stored in underground aquifers. This highlights the critical
importance of groundwater management and the professional construction of wells to
protect this massive resource from contamination.
Question 6
Prior to setting up a drill rig, what is the minimum safe distance that must be maintained between
the mast and any overhead power lines?
A) 5 feet
B) 10 feet
C) 15 feet
D) 20 feet
E) 50 feet
Correct Answer: D) 20 feet
Rationale: Safety regulations and industry standards dictate that a mast or any part of the
drilling equipment must maintain a minimum 20-foot clearance from overhead power
lines. Electricity can "arc" across a gap even without direct contact, posing a fatal risk of
electrocution to the crew and potential destruction of the equipment.
, 3
Question 7
According to confined space and trenching safety rules, at what depth is shoring required for
trench walls?
A) Over 2 feet
B) Over 4 feet
C) Over 8 feet
D) Over 10 feet
E) Shoring is never required if the soil is dry
Correct Answer: B) Over 4 feet
Rationale: OSHA and general safety standards require that any trench or excavation deeper
than 4 feet must be protected by shoring, shielding, or sloping. This prevents catastrophic
wall collapses (cave-ins), which are a leading cause of fatalities in the drilling and
construction industry.
Question 8
When leveling a drill rig at the site, what is the correct safety procedure for managing the
leveling jacks?
A) The operator should guess the level from the cab.
B) The driller's assistant should check the jacks while the operator levels the rig.
C) Jacks should only be used if the ground is soft.
D) Level the rig only after the mast is fully raised.
E) Jack pads are unnecessary if the rig is on asphalt.
Correct Answer: B) The driller's assistant should check the jacks while the operator levels
the rig.
Rationale: Leveling is a two-person operation for safety. The driller's assistant must
monitor the jacks and ground stability (ensuring suitable jack pads are used) while the
operator manipulates the controls. This ensures the rig does not tip or shift during the
critical setup phase.
Question 9
True or False? A well may be used as a sewage disposal site as long as the casing extends to the
very bottom of the borehole.
A) True
B) False
Correct Answer: B) False
Rationale: It is illegal and environmentally hazardous to use a well for sewage disposal.
Regardless of casing depth, injecting waste into the ground directly contaminates the
aquifer and can spread pathogens and pollutants to neighboring wells. Proper septic
systems or municipal sewer lines must be used instead.
, 4
Question 10
When selecting a specific location for a well on a property, what is the most important factor to
consider?
A) Proximity to the driveway for easy access
B) The aesthetics of the well cap in the landscaping
C) The point where the well is least likely to be contaminated
D) The shortest distance to the electrical panel
E) Where the grass is the greenest
Correct Answer: C) The point where the well is least likely to be contaminated
Rationale: Well siting is primarily a health and safety decision. The driller must identify
potential contamination sources (septic tanks, feedlots, chemical storage) and maintain the
maximum possible setback distances to ensure the long-term safety of the water supply.
Question 11
What is the primary function of air being forced down the drill pipe in air-rotary drilling?
A) To cool the operator
B) To clear drill cuttings from the borehole and transport them to the surface
C) To provide oxygen to the drill bit
D) To lubricate the casing
E) To prevent artesian pressure from occurring
Correct Answer: B) To clear drill cuttings from the borehole and transport them to the
surface
Rationale: In air-rotary drilling, compressed air is the "drilling fluid." It is forced down the
center of the drill pipe, exits through the bit, and carries the rock chips (cuttings) up the
annulus to the surface. This keeps the bit face clean and allows the bit to continue cutting
effectively.
Question 12
Which drilling method is considered the "best" or most effective for drilling a domestic water
well in cavernous, hard rock formations?
A) Mud Rotary
B) Bucket Rig
C) Cable Tool
D) Jetting
E) Hollow Stem Auger
Correct Answer: C) Cable Tool
Rationale: Cavernous rock often causes "lost circulation" for rotary rigs because the
drilling mud disappears into the voids. Cable tool drilling does not rely on circulating fluid;
instead, it uses a heavy bit to crush the rock. It is highly effective in hard, cavernous
formations where other methods might fail due to fluid loss.
CORRECTLY TO SCORE A+/NEWEST UPDATE!!!
Question 1
What is the primary cause of artesian pressure in a groundwater system?
A) The rotation of the earth and thermal expansion
B) Gravity acting on the water column and the presence of confining beds
C) High-pressure pumps used in nearby industrial wells
D) The chemical reaction between water and limestone
E) Suction created by the vacuum of the atmosphere
Correct Answer: B) Gravity acting on the water column and the presence of confining beds
Rationale: Artesian pressure occurs when groundwater is "trapped" under pressure
between relatively impermeable layers called confining beds (such as clay or shale).
Because the recharge area (the intake) is at a higher elevation than the well location,
gravity pulls the water down, creating hydrostatic pressure. When a well penetrates the
upper confining bed, this pressure forces the water to rise above the level of the aquifer.
Question 2
Which of the following statements regarding the origin and characteristics of sedimentary rocks
is true?
A) Sandstones were originally igneous deposits that weathered into place.
B) Shales were originally clay beds that were compacted and cemented over time.
C) Limestones contain fossils because they were formed from cooling volcanic lava.
D) Sedimentary formations rarely reach depths greater than 100 feet.
E) Sedimentary rocks are the least common environment for finding groundwater.
Correct Answer: B) Shales were originally clay beds that were compacted and cemented
over time.
Rationale: Sedimentary rocks are formed by the accumulation of minerals or organic
particles. Sandstones originate from sand deposits (river, beach, or dunes); shales originate
from silt and clay; and limestones often form from organic remains on the floors of shallow
seas. These formations are significant in drilling because they can reach depths of a mile or
more and often serve as primary aquifers.
Question 3
True or False? Groundwater, similar to surface water, has a natural tendency to flow "downhill"
(from higher hydraulic head to lower).
A) True
B) False
Correct Answer: A) True
Rationale: Groundwater movement is governed by gravity and pressure (hydraulic head).
Water moves from areas of high potential energy (higher elevation or higher pressure) to
areas of lower potential energy. This means that groundwater generally follows the slope of
the water table or the pressure gradient, moving effectively "downhill" through the pores
of the rock.
, 2
Question 4
In which of the following geological formations would a driller be LEAST likely to find a
productive water source?
A) Sandstone
B) Unconsolidated gravel
C) Limestone with caverns
D) Solid Granite
E) Fractured metamorphic rock
Correct Answer: D) Solid Granite
Rationale: Granite is an igneous rock with very low primary porosity. Unless it is
significantly fractured or weathered (secondary porosity), it contains very little space for
water to store or move. Compared to porous sandstones or cavernous limestones, solid
granite is a very poor prospect for a high-yield water well.
Question 5
What percentage of the fresh water in the United States is located underground?
A) Less than 10%
B) Approximately 25%
C) Approximately 50%
D) More than 90%
E) Exactly 100%
Correct Answer: D) More than 90%
Rationale: While surface water in lakes and rivers is more visible, the vast majority of our
nation's available fresh water is stored in underground aquifers. This highlights the critical
importance of groundwater management and the professional construction of wells to
protect this massive resource from contamination.
Question 6
Prior to setting up a drill rig, what is the minimum safe distance that must be maintained between
the mast and any overhead power lines?
A) 5 feet
B) 10 feet
C) 15 feet
D) 20 feet
E) 50 feet
Correct Answer: D) 20 feet
Rationale: Safety regulations and industry standards dictate that a mast or any part of the
drilling equipment must maintain a minimum 20-foot clearance from overhead power
lines. Electricity can "arc" across a gap even without direct contact, posing a fatal risk of
electrocution to the crew and potential destruction of the equipment.
, 3
Question 7
According to confined space and trenching safety rules, at what depth is shoring required for
trench walls?
A) Over 2 feet
B) Over 4 feet
C) Over 8 feet
D) Over 10 feet
E) Shoring is never required if the soil is dry
Correct Answer: B) Over 4 feet
Rationale: OSHA and general safety standards require that any trench or excavation deeper
than 4 feet must be protected by shoring, shielding, or sloping. This prevents catastrophic
wall collapses (cave-ins), which are a leading cause of fatalities in the drilling and
construction industry.
Question 8
When leveling a drill rig at the site, what is the correct safety procedure for managing the
leveling jacks?
A) The operator should guess the level from the cab.
B) The driller's assistant should check the jacks while the operator levels the rig.
C) Jacks should only be used if the ground is soft.
D) Level the rig only after the mast is fully raised.
E) Jack pads are unnecessary if the rig is on asphalt.
Correct Answer: B) The driller's assistant should check the jacks while the operator levels
the rig.
Rationale: Leveling is a two-person operation for safety. The driller's assistant must
monitor the jacks and ground stability (ensuring suitable jack pads are used) while the
operator manipulates the controls. This ensures the rig does not tip or shift during the
critical setup phase.
Question 9
True or False? A well may be used as a sewage disposal site as long as the casing extends to the
very bottom of the borehole.
A) True
B) False
Correct Answer: B) False
Rationale: It is illegal and environmentally hazardous to use a well for sewage disposal.
Regardless of casing depth, injecting waste into the ground directly contaminates the
aquifer and can spread pathogens and pollutants to neighboring wells. Proper septic
systems or municipal sewer lines must be used instead.
, 4
Question 10
When selecting a specific location for a well on a property, what is the most important factor to
consider?
A) Proximity to the driveway for easy access
B) The aesthetics of the well cap in the landscaping
C) The point where the well is least likely to be contaminated
D) The shortest distance to the electrical panel
E) Where the grass is the greenest
Correct Answer: C) The point where the well is least likely to be contaminated
Rationale: Well siting is primarily a health and safety decision. The driller must identify
potential contamination sources (septic tanks, feedlots, chemical storage) and maintain the
maximum possible setback distances to ensure the long-term safety of the water supply.
Question 11
What is the primary function of air being forced down the drill pipe in air-rotary drilling?
A) To cool the operator
B) To clear drill cuttings from the borehole and transport them to the surface
C) To provide oxygen to the drill bit
D) To lubricate the casing
E) To prevent artesian pressure from occurring
Correct Answer: B) To clear drill cuttings from the borehole and transport them to the
surface
Rationale: In air-rotary drilling, compressed air is the "drilling fluid." It is forced down the
center of the drill pipe, exits through the bit, and carries the rock chips (cuttings) up the
annulus to the surface. This keeps the bit face clean and allows the bit to continue cutting
effectively.
Question 12
Which drilling method is considered the "best" or most effective for drilling a domestic water
well in cavernous, hard rock formations?
A) Mud Rotary
B) Bucket Rig
C) Cable Tool
D) Jetting
E) Hollow Stem Auger
Correct Answer: C) Cable Tool
Rationale: Cavernous rock often causes "lost circulation" for rotary rigs because the
drilling mud disappears into the voids. Cable tool drilling does not rely on circulating fluid;
instead, it uses a heavy bit to crush the rock. It is highly effective in hard, cavernous
formations where other methods might fail due to fluid loss.
