NGWA AUGERING & MONITORING
WELL EXAM 2026/2027 QUESTIONS AND
ANSWERS
1. What is the primary technical advantage of using Hollow Stem Augers (HSA) for monitoring
well installation in unconsolidated materials?
A. It serves as a temporary casing to prevent borehole collapse while installing the well
string.
B. It allows for the highest rotation speeds in bedrock formations.
C. It eliminates the need for any decontamination between boreholes.
D. It provides the highest torque for drilling through boulders and cobbles.
Answer: A
Conceptual Explanation: HSA acts as a casing to keep the hole open in unstable soils,
allowing the well screen and riser to be placed through the center before the augers are
withdrawn.
2. In the context of filter pack design, what is the ‘D-60’ size?
A. The sieve size that retains 60% of the sample.
,B. The grain size at which 60% of the sample by weight is finer.
C. The grain size at which 60% of the particles are larger.
D. The average diameter of the largest 60% of particles.
Answer: B
Conceptual Explanation: D-60 represents the particle diameter at which 60% of the
material is finer; it is a standard metric used to calculate the uniformity coefficient.
3. Which method is most effective for preventing ‘heaving sands’ from entering the hollow
stem auger?
A. Increasing the drilling speed to displace the sand.
B. Applying high-pressure air through the center of the auger.
C. Using a smaller diameter auger bit.
D. Maintaining a positive head of water or drilling fluid inside the auger string.
Answer: D
Conceptual Explanation: Maintaining a higher hydraulic head inside the auger than the
external hydrostatic pressure prevents sands from flowing up into the hollow stem.
4. When installing a bentonite seal above the filter pack, what is the recommended minimum
thickness to ensure an effective seal?
A. 2 feet
B. 6 inches
, C. 5 feet
D. 10 feet
Answer: A
Conceptual Explanation: Industry standards (like ASTM D5092) generally recommend a
minimum of 2 feet of bentonite to ensure a proper hydraulic seal between the filter pack
and the grout.
5. What is the primary purpose of ‘well development’ after installation?
A. To increase the diameter of the borehole for larger pumps.
B. To test the tensile strength of the PVC casing.
C. To chemically treat the water to meet drinking standards.
D. To remove drilling fines and organize the filter pack to improve hydraulic
communication.
Answer: D
Conceptual Explanation: Well development removes fine sediments (silts/clays) and
optimizes the filter pack’s permeability to ensure representative groundwater samples.
6. Which grout mixture is typically preferred for sealing the annular space in a monitoring
well to minimize shrinkage?
A. Pure bentonite powder without water.
B. Quick-dry plaster of Paris.
WELL EXAM 2026/2027 QUESTIONS AND
ANSWERS
1. What is the primary technical advantage of using Hollow Stem Augers (HSA) for monitoring
well installation in unconsolidated materials?
A. It serves as a temporary casing to prevent borehole collapse while installing the well
string.
B. It allows for the highest rotation speeds in bedrock formations.
C. It eliminates the need for any decontamination between boreholes.
D. It provides the highest torque for drilling through boulders and cobbles.
Answer: A
Conceptual Explanation: HSA acts as a casing to keep the hole open in unstable soils,
allowing the well screen and riser to be placed through the center before the augers are
withdrawn.
2. In the context of filter pack design, what is the ‘D-60’ size?
A. The sieve size that retains 60% of the sample.
,B. The grain size at which 60% of the sample by weight is finer.
C. The grain size at which 60% of the particles are larger.
D. The average diameter of the largest 60% of particles.
Answer: B
Conceptual Explanation: D-60 represents the particle diameter at which 60% of the
material is finer; it is a standard metric used to calculate the uniformity coefficient.
3. Which method is most effective for preventing ‘heaving sands’ from entering the hollow
stem auger?
A. Increasing the drilling speed to displace the sand.
B. Applying high-pressure air through the center of the auger.
C. Using a smaller diameter auger bit.
D. Maintaining a positive head of water or drilling fluid inside the auger string.
Answer: D
Conceptual Explanation: Maintaining a higher hydraulic head inside the auger than the
external hydrostatic pressure prevents sands from flowing up into the hollow stem.
4. When installing a bentonite seal above the filter pack, what is the recommended minimum
thickness to ensure an effective seal?
A. 2 feet
B. 6 inches
, C. 5 feet
D. 10 feet
Answer: A
Conceptual Explanation: Industry standards (like ASTM D5092) generally recommend a
minimum of 2 feet of bentonite to ensure a proper hydraulic seal between the filter pack
and the grout.
5. What is the primary purpose of ‘well development’ after installation?
A. To increase the diameter of the borehole for larger pumps.
B. To test the tensile strength of the PVC casing.
C. To chemically treat the water to meet drinking standards.
D. To remove drilling fines and organize the filter pack to improve hydraulic
communication.
Answer: D
Conceptual Explanation: Well development removes fine sediments (silts/clays) and
optimizes the filter pack’s permeability to ensure representative groundwater samples.
6. Which grout mixture is typically preferred for sealing the annular space in a monitoring
well to minimize shrinkage?
A. Pure bentonite powder without water.
B. Quick-dry plaster of Paris.
