NGWA AUGERING & MONITORING
WELL EXAM QUESTIONS AND
ANSWERS
1. When drilling through heaving sands with hollow-stem augers, what is the most effective
method to prevent sand from blowing up into the augers?
A. Increasing the rotation speed of the auger string
B. Using a thicker diameter center rod
C. Maintaining a positive hydraulic head inside the auger string
D. Drilling faster to bypass the sand layer
Answer: C
Conceptual Explanation: Maintaining a positive hydraulic head by filling the hollow-stem
augers with water or drilling fluid creates downward pressure that counteracts the upward
force of heaving sands.
2. According to ASTM D5092, what is the minimum recommended thickness for the filter pack
around the monitoring well screen?
A. 1 inch
B. 4 inches
,C. 2 inches
D. 6 inches
Answer: C
Conceptual Explanation: ASTM D5092 guidelines recommend a minimum of 2 inches of
filter pack material around the screen to ensure effective filtration and sediment control.
3. Which of the following parameters is most critical for determining the slot size of a
monitoring well screen in a professional design?
A. The grain size distribution of the formation material
B. The specific gravity of the casing material
C. The total depth of the well
D. The expected pumping rate of the sampling pump
Answer: A
Conceptual Explanation: Screen slot size is typically selected based on a sieve analysis of
the formation material, usually designed to retain 90-100% of the filter pack material.
4. What is the primary disadvantage of using a bailer for sampling Volatile Organic
Compounds (VOCs)?
A. High cost of equipment
B. Difficulty in decontaminating the device
C. Potential for aeration and loss of volatiles
, D. Inability to reach depths greater than 50 feet
Answer: C
Conceptual Explanation: Bailers cause turbulence and aeration during the lifting process
and while transferring the sample to vials, which leads to the stripping of VOCs.
5. In hydrogeology, how is Transmissivity (T) defined in relation to Hydraulic Conductivity (K)?
A. T = K / S (Storativity)
B. T = K + specific yield
C. T = K^2
D. T = K * b (Saturated thickness)
Answer: D
Conceptual Explanation: Transmissivity is the product of the hydraulic conductivity and
the saturated thickness of the aquifer (T = Kb).
6. Why is bentonite pellets generally preferred over bentonite chips for sealing below the
water table?
A. Pellets are cheaper to manufacture
B. Pellets have a more uniform sinking rate and delayed hydration
C. Chips expand too much and crack the casing
D. Chips are not made of pure sodium bentonite
WELL EXAM QUESTIONS AND
ANSWERS
1. When drilling through heaving sands with hollow-stem augers, what is the most effective
method to prevent sand from blowing up into the augers?
A. Increasing the rotation speed of the auger string
B. Using a thicker diameter center rod
C. Maintaining a positive hydraulic head inside the auger string
D. Drilling faster to bypass the sand layer
Answer: C
Conceptual Explanation: Maintaining a positive hydraulic head by filling the hollow-stem
augers with water or drilling fluid creates downward pressure that counteracts the upward
force of heaving sands.
2. According to ASTM D5092, what is the minimum recommended thickness for the filter pack
around the monitoring well screen?
A. 1 inch
B. 4 inches
,C. 2 inches
D. 6 inches
Answer: C
Conceptual Explanation: ASTM D5092 guidelines recommend a minimum of 2 inches of
filter pack material around the screen to ensure effective filtration and sediment control.
3. Which of the following parameters is most critical for determining the slot size of a
monitoring well screen in a professional design?
A. The grain size distribution of the formation material
B. The specific gravity of the casing material
C. The total depth of the well
D. The expected pumping rate of the sampling pump
Answer: A
Conceptual Explanation: Screen slot size is typically selected based on a sieve analysis of
the formation material, usually designed to retain 90-100% of the filter pack material.
4. What is the primary disadvantage of using a bailer for sampling Volatile Organic
Compounds (VOCs)?
A. High cost of equipment
B. Difficulty in decontaminating the device
C. Potential for aeration and loss of volatiles
, D. Inability to reach depths greater than 50 feet
Answer: C
Conceptual Explanation: Bailers cause turbulence and aeration during the lifting process
and while transferring the sample to vials, which leads to the stripping of VOCs.
5. In hydrogeology, how is Transmissivity (T) defined in relation to Hydraulic Conductivity (K)?
A. T = K / S (Storativity)
B. T = K + specific yield
C. T = K^2
D. T = K * b (Saturated thickness)
Answer: D
Conceptual Explanation: Transmissivity is the product of the hydraulic conductivity and
the saturated thickness of the aquifer (T = Kb).
6. Why is bentonite pellets generally preferred over bentonite chips for sealing below the
water table?
A. Pellets are cheaper to manufacture
B. Pellets have a more uniform sinking rate and delayed hydration
C. Chips expand too much and crack the casing
D. Chips are not made of pure sodium bentonite
