NGWA AUGERING & MONITORING
WELL CERTIFICATION EXAM
QUESTIONS AND ANSWERS
1. Which component is most critical in preventing vertical migration of contaminants within
the borehole of a monitoring well?
A. The filter pack
B. The annular seal
C. The well screen
D. The centralizers
Answer: B
Conceptual Explanation: The annular seal, typically composed of bentonite or cement-
bentonite grout, is designed to prevent the movement of fluids and contaminants between
different stratigraphic units along the borehole.
2. When using Hollow Stem Augers (HSA), what is the primary purpose of the ‘pilot bit’ or
‘center plug’ assembly?
A. To increase the speed of penetration in hard rock
,B. To prevent soil from entering the hollow stem during drilling
C. To facilitate the installation of the filter pack
D. To lubricate the outer auger flights
Answer: B
Conceptual Explanation: The pilot bit or center plug blocks the bottom opening of the
lead auger to prevent cuttings and formation materials from entering the hollow stem
while advancing.
3. According to ASTM D5092, how should the grain size of a primary filter pack be selected?
A. Based on the depth of the water table
B. Based on the size of the slot in the well screen
C. Based on the pump capacity for well development
D. Based on the grain size distribution of the formation material
Answer: D
Conceptual Explanation: The filter pack grain size is typically selected by multiplying the
D30 size of the formation by a factor (usually 3 to 6) to ensure the pack is fine enough to
retain the formation but coarse enough to allow water flow.
4. In environmental drilling, ‘heaving sands’ are a common challenge. Which technique is
most effective to combat this when using HSAs?
A. Increasing the rotation speed of the augers
, B. Applying high-pressure air through the center bit
C. Switching to a solid stem auger immediately
D. Maintaining a positive head of water inside the augers
Answer: D
Conceptual Explanation: Heaving sands occur when hydrostatic pressure outside the
auger is higher than inside. Adding clean water to the auger stem creates a positive head,
preventing sand from surging up the stem.
5. What is the standard purpose of ‘Development’ in a monitoring well?
A. To increase the thickness of the bentonite seal
B. To remove fine-grained sediments and improve hydraulic connection to the aquifer
C. To sterilize the well casing for bacteria testing
D. To verify that the well screen is perfectly vertical
Answer: B
Conceptual Explanation: Development restores the natural hydraulic conductivity of the
formation and removes fines/drilling fluids, ensuring that collected water samples are
representative and turbidity is low.
6. Which type of grout is generally preferred for sealing the vadose zone in a monitoring well?
A. Neat cement with high heat of hydration
B. Coarse sand and gravel mix
WELL CERTIFICATION EXAM
QUESTIONS AND ANSWERS
1. Which component is most critical in preventing vertical migration of contaminants within
the borehole of a monitoring well?
A. The filter pack
B. The annular seal
C. The well screen
D. The centralizers
Answer: B
Conceptual Explanation: The annular seal, typically composed of bentonite or cement-
bentonite grout, is designed to prevent the movement of fluids and contaminants between
different stratigraphic units along the borehole.
2. When using Hollow Stem Augers (HSA), what is the primary purpose of the ‘pilot bit’ or
‘center plug’ assembly?
A. To increase the speed of penetration in hard rock
,B. To prevent soil from entering the hollow stem during drilling
C. To facilitate the installation of the filter pack
D. To lubricate the outer auger flights
Answer: B
Conceptual Explanation: The pilot bit or center plug blocks the bottom opening of the
lead auger to prevent cuttings and formation materials from entering the hollow stem
while advancing.
3. According to ASTM D5092, how should the grain size of a primary filter pack be selected?
A. Based on the depth of the water table
B. Based on the size of the slot in the well screen
C. Based on the pump capacity for well development
D. Based on the grain size distribution of the formation material
Answer: D
Conceptual Explanation: The filter pack grain size is typically selected by multiplying the
D30 size of the formation by a factor (usually 3 to 6) to ensure the pack is fine enough to
retain the formation but coarse enough to allow water flow.
4. In environmental drilling, ‘heaving sands’ are a common challenge. Which technique is
most effective to combat this when using HSAs?
A. Increasing the rotation speed of the augers
, B. Applying high-pressure air through the center bit
C. Switching to a solid stem auger immediately
D. Maintaining a positive head of water inside the augers
Answer: D
Conceptual Explanation: Heaving sands occur when hydrostatic pressure outside the
auger is higher than inside. Adding clean water to the auger stem creates a positive head,
preventing sand from surging up the stem.
5. What is the standard purpose of ‘Development’ in a monitoring well?
A. To increase the thickness of the bentonite seal
B. To remove fine-grained sediments and improve hydraulic connection to the aquifer
C. To sterilize the well casing for bacteria testing
D. To verify that the well screen is perfectly vertical
Answer: B
Conceptual Explanation: Development restores the natural hydraulic conductivity of the
formation and removes fines/drilling fluids, ensuring that collected water samples are
representative and turbidity is low.
6. Which type of grout is generally preferred for sealing the vadose zone in a monitoring well?
A. Neat cement with high heat of hydration
B. Coarse sand and gravel mix
