NGWA AUGERING & MONITORING
WELL ADVANCED EXAM QUESTIONS
AND ANSWERS
1. What is the primary technical advantage of using hollow-stem augers over solid-stem
augers in unconsolidated formations?
A. They allow for higher rotational speeds in dense clays.
B. They act as a temporary casing to prevent borehole collapse during well installation.
C. They eliminate the need for any decontamination between boreholes.
D. They are capable of drilling through crystalline bedrock more efficiently.
Answer: B
Conceptual Explanation: Hollow-stem augers serve as a temporary casing, allowing the
well screen and casing to be inserted through the center of the auger flights, which
prevents the borehole from collapsing in loose or saturated materials.
2. When installing a filter pack in a monitoring well, what is the standard practice to ensure
proper placement and avoid bridging?
A. Pouring the sand rapidly from the surface to ensure momentum.
,B. Mixing the sand with bentonite powder before installation.
C. Using a tremie pipe to place the sand from the bottom up.
D. Using a high-pressure air compressor to blow the sand into the annulus.
Answer: C
Conceptual Explanation: The use of a tremie pipe ensures that the filter pack is placed
evenly and prevents ‘bridging’ or gaps in the annular space, which could compromise the
well’s integrity.
3. Which of the following materials is generally considered the most chemically inert for
monitoring well casing in environments with high concentrations of organic solvents?
A. Carbon Steel
B. Schedule 40 PVC
C. Galvanized Steel
D. Stainless Steel (304 or 316)
Answer: D
Conceptual Explanation: Stainless steel provides superior resistance to chemical
degradation and leaching when exposed to many organic solvents compared to PVC or
carbon steel.
4. What is the ‘uniformity coefficient’ (Cu) of a filter pack sand, and why is it important?
A. The weight of the sand divided by its volume; it determines the grout mix.
, B. The ratio of the 60% passing size to the 10% passing size; it indicates grain size
distribution.
C. The measure of angularity; it determines the filtration efficiency.
D. The percentage of silica content; it determines chemical stability.
Answer: B
Conceptual Explanation: The uniformity coefficient (D60/D10) indicates how well-sorted
the sand is. A low Cu (less than 2.5) is preferred for filter packs to ensure high permeability
and effective filtration.
5. In the context of well development, what is the ‘over-pumping’ method designed to
achieve?
A. To increase the water temperature for better sampling.
B. To create a high-velocity flow that draws fines out of the formation and filter pack.
C. To sterilize the screen by friction heat.
D. To test the maximum capacity of the drilling rig’s engine.
Answer: B
Conceptual Explanation: Over-pumping involves pumping at a rate higher than the
intended sampling rate to induce high-velocity flow, which removes fine-grained sediments
(silts and clays) from the near-well zone.
WELL ADVANCED EXAM QUESTIONS
AND ANSWERS
1. What is the primary technical advantage of using hollow-stem augers over solid-stem
augers in unconsolidated formations?
A. They allow for higher rotational speeds in dense clays.
B. They act as a temporary casing to prevent borehole collapse during well installation.
C. They eliminate the need for any decontamination between boreholes.
D. They are capable of drilling through crystalline bedrock more efficiently.
Answer: B
Conceptual Explanation: Hollow-stem augers serve as a temporary casing, allowing the
well screen and casing to be inserted through the center of the auger flights, which
prevents the borehole from collapsing in loose or saturated materials.
2. When installing a filter pack in a monitoring well, what is the standard practice to ensure
proper placement and avoid bridging?
A. Pouring the sand rapidly from the surface to ensure momentum.
,B. Mixing the sand with bentonite powder before installation.
C. Using a tremie pipe to place the sand from the bottom up.
D. Using a high-pressure air compressor to blow the sand into the annulus.
Answer: C
Conceptual Explanation: The use of a tremie pipe ensures that the filter pack is placed
evenly and prevents ‘bridging’ or gaps in the annular space, which could compromise the
well’s integrity.
3. Which of the following materials is generally considered the most chemically inert for
monitoring well casing in environments with high concentrations of organic solvents?
A. Carbon Steel
B. Schedule 40 PVC
C. Galvanized Steel
D. Stainless Steel (304 or 316)
Answer: D
Conceptual Explanation: Stainless steel provides superior resistance to chemical
degradation and leaching when exposed to many organic solvents compared to PVC or
carbon steel.
4. What is the ‘uniformity coefficient’ (Cu) of a filter pack sand, and why is it important?
A. The weight of the sand divided by its volume; it determines the grout mix.
, B. The ratio of the 60% passing size to the 10% passing size; it indicates grain size
distribution.
C. The measure of angularity; it determines the filtration efficiency.
D. The percentage of silica content; it determines chemical stability.
Answer: B
Conceptual Explanation: The uniformity coefficient (D60/D10) indicates how well-sorted
the sand is. A low Cu (less than 2.5) is preferred for filter packs to ensure high permeability
and effective filtration.
5. In the context of well development, what is the ‘over-pumping’ method designed to
achieve?
A. To increase the water temperature for better sampling.
B. To create a high-velocity flow that draws fines out of the formation and filter pack.
C. To sterilize the screen by friction heat.
D. To test the maximum capacity of the drilling rig’s engine.
Answer: B
Conceptual Explanation: Over-pumping involves pumping at a rate higher than the
intended sampling rate to induce high-velocity flow, which removes fine-grained sediments
(silts and clays) from the near-well zone.
