NGWA - STUDY QUESTIONS - GENERAL DRILLING EXAM
(ANSWERED) CORRECTLY TO SCORE A+/NEWEST UPDATE 2026
Question 1
In general drilling operations, what is the primary cause of artesian pressure in an aquifer?
A) Excessive pumping from nearby wells
B) The chemical composition of the groundwater
C) The result of gravity and confining beds
D) The rotational speed of the drill bit
E) Atmospheric pressure changes at the surface
Correct Answer: C) The result of gravity and confining beds
Rationale: Artesian pressure occurs when groundwater is trapped between impermeable
layers (confining beds). The weight of the water at higher elevations in the recharge area
creates pressure throughout the confined system due to gravity.
Question 2
What is a true statement regarding the geological origin of sandstones?
A) They were originally mucky bottoms of shallow seas.
B) They were once clay beds compressed over time.
C) They were once sand deposits from rivers, beaches, or dunes.
D) They are formed primarily from cooled volcanic magma.
E) They are metamorphic rocks formed from granite.
Correct Answer: C) They were once sand deposits from rivers, beaches, or dunes.
Rationale: Sandstone is a sedimentary rock formed by the accumulation and lithification of
sand-sized mineral grains or rock fragments, typically deposited by wind or water.
Question 3
Which type of rock is most likely to contain fossils based on its origin as the mucky bottom of
shallow seas?
A) Granite
B) Basalt
C) Limestone
D) Quartzite
E) Schist
Correct Answer: C) Limestone
Rationale: Limestone is often biological in origin, forming from the accumulation of shell,
coral, algal, and fecal debris in shallow, warm marine waters, which frequently preserves
fossils.
Question 4
Shales are sedimentary rocks that were originally composed of which of the following?
A) Volcanic ash
B) River gravel
, 2
C) Clay beds
D) Molten lava
E) Pure quartz sand
Correct Answer: C) Clay beds
Rationale: Shale is a fine-grained sedimentary rock that forms from the compaction of silt
and clay-size mineral particles, commonly referred to as mud or clay.
Question 5
To what depth may sedimentary formations potentially reach in various geological regions?
A) No more than 100 feet
B) Exactly 500 feet
C) A mile or more
D) They never exceed the water table depth
E) Only 1,000 feet
Correct Answer: C) A mile or more
Rationale: Sedimentary basins can be extremely deep, with layers of rock accumulating
over millions of years to reach thicknesses exceeding several miles.
Question 6
Which statement is true regarding the flow of groundwater?
A) It always flows toward the center of the earth.
B) Like surface water, it has a tendency to flow downhill.
C) It flows from areas of low pressure to high pressure.
D) It only moves vertically through the soil.
E) It remains stationary unless pumped by a well.
Correct Answer: B) Like surface water, it has a tendency to flow downhill.
Rationale: Groundwater moves in response to hydraulic gradients, generally flowing from
higher elevations (high head) to lower elevations (low head), similar to surface runoff.
Question 7
What are the three main classifications of rock found in the Earth's crust?
A) Soft, Medium, and Hard
B) Primary, Secondary, and Tertiary
C) Igneous, Sedimentary, and Metamorphic
D) Saturated, Unsaturated, and Confined
E) Porous, Permeable, and Crystalline
Correct Answer: C) Igneous, Sedimentary, and Metamorphic
Rationale: These three categories define how rocks are formed: cooling magma (igneous),
deposited particles (sedimentary), or heat and pressure (metamorphic).
, 3
Question 8
In which of the following geological formations would a driller be LEAST likely to find a
productive water source?
A) Unconsolidated sand
B) Fractured limestone
C) Granite
D) Sandstone
E) Gravel
Correct Answer: C) Granite
Rationale: Granite is an igneous rock with very low primary porosity. Unless it is highly
fractured, it is generally considered a poor source for significant groundwater yields.
Question 9
What percentage of the nation's fresh water is estimated to be stored underground?
A) Less than 10%
B) Approximately 50%
C) Exactly 75%
D) More than 90%
E) 100%
Correct Answer: D) More than 90%
Rationale: Groundwater represents the vast majority of accessible fresh water on Earth,
excluding ice caps and glaciers, dwarfing the volume found in lakes and rivers.
Question 10
Prior to setting up a drill rig, what is the minimum required distance the mast should be kept
from 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 NGWA standards require a minimum 20-foot clearance
from power lines to prevent accidental electrocution if the mast or cables sway or move.
Question 11
Which of the following must be completed before a driller begins setting the rig at a new site?
A) Paint the rig a bright color for visibility.
B) Locate all buried materials and utilities.
C) Drain the hydraulic fluid.
(ANSWERED) CORRECTLY TO SCORE A+/NEWEST UPDATE 2026
Question 1
In general drilling operations, what is the primary cause of artesian pressure in an aquifer?
A) Excessive pumping from nearby wells
B) The chemical composition of the groundwater
C) The result of gravity and confining beds
D) The rotational speed of the drill bit
E) Atmospheric pressure changes at the surface
Correct Answer: C) The result of gravity and confining beds
Rationale: Artesian pressure occurs when groundwater is trapped between impermeable
layers (confining beds). The weight of the water at higher elevations in the recharge area
creates pressure throughout the confined system due to gravity.
Question 2
What is a true statement regarding the geological origin of sandstones?
A) They were originally mucky bottoms of shallow seas.
B) They were once clay beds compressed over time.
C) They were once sand deposits from rivers, beaches, or dunes.
D) They are formed primarily from cooled volcanic magma.
E) They are metamorphic rocks formed from granite.
Correct Answer: C) They were once sand deposits from rivers, beaches, or dunes.
Rationale: Sandstone is a sedimentary rock formed by the accumulation and lithification of
sand-sized mineral grains or rock fragments, typically deposited by wind or water.
Question 3
Which type of rock is most likely to contain fossils based on its origin as the mucky bottom of
shallow seas?
A) Granite
B) Basalt
C) Limestone
D) Quartzite
E) Schist
Correct Answer: C) Limestone
Rationale: Limestone is often biological in origin, forming from the accumulation of shell,
coral, algal, and fecal debris in shallow, warm marine waters, which frequently preserves
fossils.
Question 4
Shales are sedimentary rocks that were originally composed of which of the following?
A) Volcanic ash
B) River gravel
, 2
C) Clay beds
D) Molten lava
E) Pure quartz sand
Correct Answer: C) Clay beds
Rationale: Shale is a fine-grained sedimentary rock that forms from the compaction of silt
and clay-size mineral particles, commonly referred to as mud or clay.
Question 5
To what depth may sedimentary formations potentially reach in various geological regions?
A) No more than 100 feet
B) Exactly 500 feet
C) A mile or more
D) They never exceed the water table depth
E) Only 1,000 feet
Correct Answer: C) A mile or more
Rationale: Sedimentary basins can be extremely deep, with layers of rock accumulating
over millions of years to reach thicknesses exceeding several miles.
Question 6
Which statement is true regarding the flow of groundwater?
A) It always flows toward the center of the earth.
B) Like surface water, it has a tendency to flow downhill.
C) It flows from areas of low pressure to high pressure.
D) It only moves vertically through the soil.
E) It remains stationary unless pumped by a well.
Correct Answer: B) Like surface water, it has a tendency to flow downhill.
Rationale: Groundwater moves in response to hydraulic gradients, generally flowing from
higher elevations (high head) to lower elevations (low head), similar to surface runoff.
Question 7
What are the three main classifications of rock found in the Earth's crust?
A) Soft, Medium, and Hard
B) Primary, Secondary, and Tertiary
C) Igneous, Sedimentary, and Metamorphic
D) Saturated, Unsaturated, and Confined
E) Porous, Permeable, and Crystalline
Correct Answer: C) Igneous, Sedimentary, and Metamorphic
Rationale: These three categories define how rocks are formed: cooling magma (igneous),
deposited particles (sedimentary), or heat and pressure (metamorphic).
, 3
Question 8
In which of the following geological formations would a driller be LEAST likely to find a
productive water source?
A) Unconsolidated sand
B) Fractured limestone
C) Granite
D) Sandstone
E) Gravel
Correct Answer: C) Granite
Rationale: Granite is an igneous rock with very low primary porosity. Unless it is highly
fractured, it is generally considered a poor source for significant groundwater yields.
Question 9
What percentage of the nation's fresh water is estimated to be stored underground?
A) Less than 10%
B) Approximately 50%
C) Exactly 75%
D) More than 90%
E) 100%
Correct Answer: D) More than 90%
Rationale: Groundwater represents the vast majority of accessible fresh water on Earth,
excluding ice caps and glaciers, dwarfing the volume found in lakes and rivers.
Question 10
Prior to setting up a drill rig, what is the minimum required distance the mast should be kept
from 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 NGWA standards require a minimum 20-foot clearance
from power lines to prevent accidental electrocution if the mast or cables sway or move.
Question 11
Which of the following must be completed before a driller begins setting the rig at a new site?
A) Paint the rig a bright color for visibility.
B) Locate all buried materials and utilities.
C) Drain the hydraulic fluid.
