VA Master Onsite Sewage System Installer Alternative Exam
1. What is the primary purpose of a septic tank in an onsite sewage system?
A) To aerate wastewater
B) To filter solids from liquids
C) To store sewage temporarily
D) To digest solid waste
Answer: B) To filter solids from liquids
Explanation: The septic tank's main function is to separate solids from liquids, allowing the
solids to settle and partially decompose, while the liquids flow to the next stage of the
treatment process.
2. Which of the following soil types is least suitable for an onsite sewage system?
A) Sandy loam
B) Clay
C) Silt loam
D) Gravel
Answer: B) Clay
Explanation: Clay soil has low permeability, which can prevent proper drainage and
absorption of effluent, making it unsuitable for onsite sewage systems.
3. How often should a septic tank typically be pumped out?
A) Every year
B) Every 3-5 years
C) Every 10 years
D) Only when it overflows
Answer: B) Every 3-5 years
1
,VA Master Onsite Sewage System Installer Alternative Exam
Explanation: Regular pumping every 3-5 years helps prevent solids from building up to the
point where they overflow into the drain field, which can cause system failure.
4. What is the purpose of an effluent filter in a septic system?
A) To reduce odor
B) To increase bacterial activity
C) To prevent solids from entering the drain field
D) To aerate the wastewater
Answer: C) To prevent solids from entering the drain field
Explanation: Effluent filters help keep solids out of the drain field, extending its life and
maintaining its function.
5. What is the minimum required distance between a septic tank and a well?
A) 10 feet
B) 50 feet
C) 100 feet
D) 200 feet
Answer: C) 100 feet
Explanation: The minimum distance helps prevent contamination of drinking water sources
by bacteria and other pathogens from the septic system.
6. In a gravity flow septic system, what ensures the even distribution of effluent into the
drain field?
A) A dosing chamber
B) A distribution box
2
,VA Master Onsite Sewage System Installer Alternative Exam
C) An effluent filter
D) A baffle
Answer: B) A distribution box
Explanation: A distribution box evenly distributes effluent from the septic tank into the drain
field lines.
7. What type of onsite sewage system is most suitable for use in areas with high
groundwater tables?
A) Conventional septic system
B) Mound system
C) Aerobic treatment unit
D) Drip distribution system
Answer: B) Mound system
Explanation: Mound systems are designed to provide additional treatment and elevate the
drain field above the natural soil level to avoid contact with high groundwater.
8. What is the purpose of a baffle in a septic tank?
A) To enhance bacterial growth
B) To separate solids and liquids
C) To prevent scum and sludge from exiting the tank
D) To aerate the effluent
Answer: C) To prevent scum and sludge from exiting the tank
Explanation: Baffles help keep solids (scum and sludge) within the tank, preventing them
from entering and clogging the drain field.
9. Which of the following is an indication that a septic system is functioning properly?
3
, VA Master Onsite Sewage System Installer Alternative Exam
A) Puddles of water on the surface above the drain field
B) Slow drainage in household fixtures
C) Foul odors around the septic tank
D) Clear effluent in the distribution box
Answer: D) Clear effluent in the distribution box
Explanation: Clear effluent in the distribution box indicates that the septic tank is effectively
separating solids from liquids and the effluent being distributed is relatively free of solids.
10. What is a typical lifespan of a properly maintained drain field?
A) 5-10 years
B) 10-20 years
C) 20-30 years
D) Over 50 years
Answer: C) 20-30 years
Explanation: A well-maintained drain field can last 20-30 years, depending on usage, soil
conditions, and maintenance practices.
11. What is a key advantage of using an aerobic treatment unit (ATU) over a
conventional septic system?
A) Lower maintenance costs
B) Reduced need for pumping
C) Better effluent quality
D) Simplicity of design
Answer: C) Better effluent quality
Explanation: ATUs provide a higher level of treatment, resulting in better effluent quality that
can be safely discharged to the environment or reused for irrigation.
4
1. What is the primary purpose of a septic tank in an onsite sewage system?
A) To aerate wastewater
B) To filter solids from liquids
C) To store sewage temporarily
D) To digest solid waste
Answer: B) To filter solids from liquids
Explanation: The septic tank's main function is to separate solids from liquids, allowing the
solids to settle and partially decompose, while the liquids flow to the next stage of the
treatment process.
2. Which of the following soil types is least suitable for an onsite sewage system?
A) Sandy loam
B) Clay
C) Silt loam
D) Gravel
Answer: B) Clay
Explanation: Clay soil has low permeability, which can prevent proper drainage and
absorption of effluent, making it unsuitable for onsite sewage systems.
3. How often should a septic tank typically be pumped out?
A) Every year
B) Every 3-5 years
C) Every 10 years
D) Only when it overflows
Answer: B) Every 3-5 years
1
,VA Master Onsite Sewage System Installer Alternative Exam
Explanation: Regular pumping every 3-5 years helps prevent solids from building up to the
point where they overflow into the drain field, which can cause system failure.
4. What is the purpose of an effluent filter in a septic system?
A) To reduce odor
B) To increase bacterial activity
C) To prevent solids from entering the drain field
D) To aerate the wastewater
Answer: C) To prevent solids from entering the drain field
Explanation: Effluent filters help keep solids out of the drain field, extending its life and
maintaining its function.
5. What is the minimum required distance between a septic tank and a well?
A) 10 feet
B) 50 feet
C) 100 feet
D) 200 feet
Answer: C) 100 feet
Explanation: The minimum distance helps prevent contamination of drinking water sources
by bacteria and other pathogens from the septic system.
6. In a gravity flow septic system, what ensures the even distribution of effluent into the
drain field?
A) A dosing chamber
B) A distribution box
2
,VA Master Onsite Sewage System Installer Alternative Exam
C) An effluent filter
D) A baffle
Answer: B) A distribution box
Explanation: A distribution box evenly distributes effluent from the septic tank into the drain
field lines.
7. What type of onsite sewage system is most suitable for use in areas with high
groundwater tables?
A) Conventional septic system
B) Mound system
C) Aerobic treatment unit
D) Drip distribution system
Answer: B) Mound system
Explanation: Mound systems are designed to provide additional treatment and elevate the
drain field above the natural soil level to avoid contact with high groundwater.
8. What is the purpose of a baffle in a septic tank?
A) To enhance bacterial growth
B) To separate solids and liquids
C) To prevent scum and sludge from exiting the tank
D) To aerate the effluent
Answer: C) To prevent scum and sludge from exiting the tank
Explanation: Baffles help keep solids (scum and sludge) within the tank, preventing them
from entering and clogging the drain field.
9. Which of the following is an indication that a septic system is functioning properly?
3
, VA Master Onsite Sewage System Installer Alternative Exam
A) Puddles of water on the surface above the drain field
B) Slow drainage in household fixtures
C) Foul odors around the septic tank
D) Clear effluent in the distribution box
Answer: D) Clear effluent in the distribution box
Explanation: Clear effluent in the distribution box indicates that the septic tank is effectively
separating solids from liquids and the effluent being distributed is relatively free of solids.
10. What is a typical lifespan of a properly maintained drain field?
A) 5-10 years
B) 10-20 years
C) 20-30 years
D) Over 50 years
Answer: C) 20-30 years
Explanation: A well-maintained drain field can last 20-30 years, depending on usage, soil
conditions, and maintenance practices.
11. What is a key advantage of using an aerobic treatment unit (ATU) over a
conventional septic system?
A) Lower maintenance costs
B) Reduced need for pumping
C) Better effluent quality
D) Simplicity of design
Answer: C) Better effluent quality
Explanation: ATUs provide a higher level of treatment, resulting in better effluent quality that
can be safely discharged to the environment or reused for irrigation.
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