Ontario On-Site Sewage Systems Technical Exam QUESTIONS AND VERIFIED ANSWERS WITH RATIONALES JUST RELEASED .pdf

Ontario On-Site Sewage Systems Technical Exam
QUESTIONS AND VERIFIED ANSWERS WITH RATIONALES
JUST RELEASED .pdf

1. What is the maximum daily design flow for sewage systems
covered under Part 8 of the Ontario Building Code?
A. 5,000 litres per day
B. 10,000 litres per day
C. 15,000 litres per day
D. 20,000 litres per day
Correct Answer: B. 10,000 litres per day
Explanation: Part 8 of the OBC applies to on-site sewage systems
with a design capacity of 10,000 litres per day or less .
2. Which Class of sewage system consists of a septic tank followed
by a leaching bed?
A. Class 1
B. Class 2
C. Class 3
D. Class 4
Correct Answer: D. Class 4
Explanation: A Class 4 sewage system is the most common type,
consisting of a treatment unit (septic tank) connected to a leaching
bed constructed in accordance with OBC requirements .

,3. A Class 2 sewage system is designed to receive only:
A. Blackwater only
B. Greywater only
C. Stormwater
D. Industrial waste
Correct Answer: B. Greywater only
Explanation: According to Article 8.1.2.1. of the OBC, a Class 2
sewage system is defined as a greywater system .
4. Which of the following is classified as a Class 3 sewage system
under the Ontario Building Code?
A. Cesspool
B. Holding tank
C. Greywater system
D. Septic tank with leaching bed
Correct Answer: A. Cesspool
Explanation: Part 8 specifically identifies a cesspool as a Class 3
sewage system .
5. What is the primary purpose of an on-site sewage system?
A. To store wastewater for later disposal
B. To treat and dispose of domestic wastewater safely
C. To filter drinking water
D. To collect stormwater runoff
Correct Answer: B. To treat and dispose of domestic wastewater
safely

,Explanation: The primary function of a septic system is to safely
treat and dispose of domestic wastewater on-site, preventing
contamination of groundwater and surface water .
6. Which of the following is NOT a class of sewage system under the
Ontario Building Code?
A. Class 1
B. Class 2
C. Class 5
D. Class 6
Correct Answer: D. Class 6
Explanation: The OBC classifies sewage systems as Class 1 through
Class 5. There is no Class 6 .
7. What is the minimum vertical separation distance required
between the bottom of a leaching bed and the seasonal high water
table?
A. 0.3 m
B. 0.6 m
C. 1.2 m
D. 2.0 m
Correct Answer: C. 1.2 m
Explanation: Ontario regulations require a minimum of 1.2 m
separation between the bottom of the leaching bed and the seasonal
high water table to ensure proper treatment .

, 8. Which type of system is classified as a Class 1 sewage system?
A. Chemical toilet or composting toilet
B. Greywater leaching pit
C. Septic tank with absorption trench
D. Holding tank requiring pump-outs
Correct Answer: A. Chemical toilet or composting toilet
Explanation: Class 1 systems are waterless closets including
composting toilets, chemical toilets, incinerating toilets, and privies .
9. What is the base daily design sanitary sewage flow (Q) for a 3-
bedroom residential dwelling under the OBC?
A. 750 L/day
B. 1,100 L/day
C. 1,600 L/day
D. 2,000 L/day
Correct Answer: C. 1,600 L/day
Explanation: Table 8.2.1.3.A of the Ontario Building Code specifies
that the base daily design flow (Q) for a 3-bedroom residential
occupancy is 1,600 Litres per day .
10. What is the primary function of a septic tank?
A. Completely disinfect wastewater
B. Separate solids and provide anaerobic treatment
C. Aerate wastewater continuously
D. Remove all dissolved contaminants
Correct Answer: B. Separate solids and provide anaerobic