Louisiana Department of Health – Certified
Installer of Individual Onsite Wastewater
Treatment Systems Actual Exam (Latest Update
) Questions & Answers with Rationales|
100% Correct | Grade. Covers general knowledge,
state-specific requirements, system design,
installation
While inspecting a proposed site for a new septic system, you notice that the soil has a
high clay content and poor drainage. What is the correct course of action before
proceeding with installation?
1. A) Conduct a detailed percolation test, evaluate alternative drainfield designs, and
obtain approval from the local health department ✅
2. B) Install a standard septic system immediately
3. C) Add gravel to the soil and proceed
4. D) Use a standard absorption trench without testing
Answer: A
Rationale: Soil with high clay content may not percolate properly, which could
cause system failure. Proper testing and approval are required.
2. During the installation of a septic tank, you notice that the excavation has not been
stabilized and there is loose soil at the edges. What safety procedures should you
implement?
A) Shore up excavation walls, ensure safe access, and prevent cave-ins before
proceeding ✅
B) Proceed with installation immediately
C) Only place warning signs around the site
, D) Fill in the excavation and start a new site
Answer: A
Rationale: OSHA and safety standards require stabilizing excavations to prevent
worker injury.
3. A client requests an aerobic treatment unit instead of a conventional septic tank. Which
factors must you evaluate before installation?
A) Site suitability, electrical supply, maintenance requirements, and local health
department approval ✅
B) Install it the same way as a conventional septic system
C) Only verify tank size
D) Ignore local regulations
Answer: A
Rationale: Aerobic units require proper siting, electricity, and compliance with
regulations.
4. While preparing the drainfield, you notice standing water on the site. What steps
should you take?
A) Delay installation, improve drainage, and reassess site conditions ✅
B) Install the system anyway
C) Cover the area with gravel and proceed
D) Pump water away and ignore soil saturation
Answer: A
Rationale: Saturated soil can lead to system failure and contamination of
groundwater.
5. A homeowner reports slow drainage from their septic system. Upon inspection, you
find solids have accumulated in the tank. What is the correct action?
A) Pump the tank, inspect baffles, and schedule regular maintenance ✅
B) Ignore the problem
C) Replace the drainfield only
D) Add chemicals to dissolve solids
Answer: A
Rationale: Regular pumping and inspection prevent backup and system failure.
, 6. During installation, you must maintain a minimum distance between the septic tank
and a nearby water well. What is the primary reason for this requirement?
A) Prevent contamination of drinking water by effluent ✅
B) Ensure ease of access
C) For aesthetic purposes
D) To comply with electrical codes
Answer: A
Rationale: Health codes require minimum separation to protect groundwater from
contamination.
7. A drainfield trench is designed with 18 inches of gravel and perforated pipe. What is
the purpose of the gravel layer?
A) Facilitate even distribution and percolation of effluent ✅
B) Provide structural support only
C) Prevent root intrusion only
D) Decorative purposes
Answer: A
Rationale: Gravel provides a medium for effluent to disperse and helps prevent
clogging.
8. While performing a site evaluation, you notice that the slope is greater than
recommended for a conventional drainfield. What should you do?
A) Consider alternative system designs, such as a mound system, and consult the
health department ✅
B) Proceed with a standard trench system
C) Level the slope with fill dirt and ignore regulations
D) Reduce the tank size to compensate
Answer: A
Rationale: Excessive slope can cause effluent to flow too quickly, leading to
system failure.
Installer of Individual Onsite Wastewater
Treatment Systems Actual Exam (Latest Update
) Questions & Answers with Rationales|
100% Correct | Grade. Covers general knowledge,
state-specific requirements, system design,
installation
While inspecting a proposed site for a new septic system, you notice that the soil has a
high clay content and poor drainage. What is the correct course of action before
proceeding with installation?
1. A) Conduct a detailed percolation test, evaluate alternative drainfield designs, and
obtain approval from the local health department ✅
2. B) Install a standard septic system immediately
3. C) Add gravel to the soil and proceed
4. D) Use a standard absorption trench without testing
Answer: A
Rationale: Soil with high clay content may not percolate properly, which could
cause system failure. Proper testing and approval are required.
2. During the installation of a septic tank, you notice that the excavation has not been
stabilized and there is loose soil at the edges. What safety procedures should you
implement?
A) Shore up excavation walls, ensure safe access, and prevent cave-ins before
proceeding ✅
B) Proceed with installation immediately
C) Only place warning signs around the site
, D) Fill in the excavation and start a new site
Answer: A
Rationale: OSHA and safety standards require stabilizing excavations to prevent
worker injury.
3. A client requests an aerobic treatment unit instead of a conventional septic tank. Which
factors must you evaluate before installation?
A) Site suitability, electrical supply, maintenance requirements, and local health
department approval ✅
B) Install it the same way as a conventional septic system
C) Only verify tank size
D) Ignore local regulations
Answer: A
Rationale: Aerobic units require proper siting, electricity, and compliance with
regulations.
4. While preparing the drainfield, you notice standing water on the site. What steps
should you take?
A) Delay installation, improve drainage, and reassess site conditions ✅
B) Install the system anyway
C) Cover the area with gravel and proceed
D) Pump water away and ignore soil saturation
Answer: A
Rationale: Saturated soil can lead to system failure and contamination of
groundwater.
5. A homeowner reports slow drainage from their septic system. Upon inspection, you
find solids have accumulated in the tank. What is the correct action?
A) Pump the tank, inspect baffles, and schedule regular maintenance ✅
B) Ignore the problem
C) Replace the drainfield only
D) Add chemicals to dissolve solids
Answer: A
Rationale: Regular pumping and inspection prevent backup and system failure.
, 6. During installation, you must maintain a minimum distance between the septic tank
and a nearby water well. What is the primary reason for this requirement?
A) Prevent contamination of drinking water by effluent ✅
B) Ensure ease of access
C) For aesthetic purposes
D) To comply with electrical codes
Answer: A
Rationale: Health codes require minimum separation to protect groundwater from
contamination.
7. A drainfield trench is designed with 18 inches of gravel and perforated pipe. What is
the purpose of the gravel layer?
A) Facilitate even distribution and percolation of effluent ✅
B) Provide structural support only
C) Prevent root intrusion only
D) Decorative purposes
Answer: A
Rationale: Gravel provides a medium for effluent to disperse and helps prevent
clogging.
8. While performing a site evaluation, you notice that the slope is greater than
recommended for a conventional drainfield. What should you do?
A) Consider alternative system designs, such as a mound system, and consult the
health department ✅
B) Proceed with a standard trench system
C) Level the slope with fill dirt and ignore regulations
D) Reduce the tank size to compensate
Answer: A
Rationale: Excessive slope can cause effluent to flow too quickly, leading to
system failure.
