Commercial Contractor Exam Questions
with Correct Answers 2025
Septic Tank Sizing - CORRECT ANSWER -Sized for daily peakBflow volume
Minimum Septic Tank Size - CORRECT ANSWER -1000 gallons
What type of PVC should all tanks be equipped with at the inlet and outlet? -
CORRECT ANSWER -4" PVC
What is the minimum extension of liquid for tees in tanks? - CORRECT ANSWER -
25% of liquid depth
What is the maximum extension of liquid for tees in tanks? - CORRECT ANSWER -
50% of liquid depth
How far below the invert of the inlet tee should the invert of the outlet tee be located? -
CORRECT ANSWER -2" below
What should outlet tees be equipped with? - CORRECT ANSWER -
An effluent filter designed to handle both the daily flow volume and wastewater characteristics
Tank Dimensions - CORRECT ANSWER -
Length shall be 1 1/2 times the width and shall have 2 compartments.
What must be reinforced in poured-in-place septic tanks? - CORRECT ANSWER -
Walls and bottom of the tanks must be reinforced.
, What type of reinforcing rods mustBbe used for tank lids? - CORRECT ANSWER -
3/8" steel reinforcing rods.
What is the uniform live load that a septicBtank must withstand? - CORRECT ANSWER -
150 pounds per square foot.
What additional loads must a septic tank be able to withstand? - CORRECT ANSWER -
All loads to which an underground tank is normally subjected.
Concrete Specifications - CORRECT ANSWER -Minimum 28-
day compressive strength of 4000 pounds per square inch.
What is the requirement for a dosing device in systems with 500 linear feet of field line? -
CORRECT ANSWER -500 linear feet of field line or more must have a dosing device.
What is the requirement for systems with over 500 linear feet but less than 1000 linear feet? -
CORRECT ANSWER -They are only required to have a single pump.
What are the construction material requirements for dosing tanks? - CORRECT ANSWER -
Same construction materials and reinforcement requirements as septic tanks.
Can one or two piece dosing tanks be used? - CORRECT ANSWER -
Yes, one or two piece dosing tanks may be used.
How should two piece dosing tank sections be joined? - CORRECT ANSWER -
They must be joined by using mastic, butyl rubber, or other pliable sealant that is waterproof.
What is the required diameter for a water-tight access cover on dosing tanks? -
CORRECT ANSWER -At least 24 inches
with Correct Answers 2025
Septic Tank Sizing - CORRECT ANSWER -Sized for daily peakBflow volume
Minimum Septic Tank Size - CORRECT ANSWER -1000 gallons
What type of PVC should all tanks be equipped with at the inlet and outlet? -
CORRECT ANSWER -4" PVC
What is the minimum extension of liquid for tees in tanks? - CORRECT ANSWER -
25% of liquid depth
What is the maximum extension of liquid for tees in tanks? - CORRECT ANSWER -
50% of liquid depth
How far below the invert of the inlet tee should the invert of the outlet tee be located? -
CORRECT ANSWER -2" below
What should outlet tees be equipped with? - CORRECT ANSWER -
An effluent filter designed to handle both the daily flow volume and wastewater characteristics
Tank Dimensions - CORRECT ANSWER -
Length shall be 1 1/2 times the width and shall have 2 compartments.
What must be reinforced in poured-in-place septic tanks? - CORRECT ANSWER -
Walls and bottom of the tanks must be reinforced.
, What type of reinforcing rods mustBbe used for tank lids? - CORRECT ANSWER -
3/8" steel reinforcing rods.
What is the uniform live load that a septicBtank must withstand? - CORRECT ANSWER -
150 pounds per square foot.
What additional loads must a septic tank be able to withstand? - CORRECT ANSWER -
All loads to which an underground tank is normally subjected.
Concrete Specifications - CORRECT ANSWER -Minimum 28-
day compressive strength of 4000 pounds per square inch.
What is the requirement for a dosing device in systems with 500 linear feet of field line? -
CORRECT ANSWER -500 linear feet of field line or more must have a dosing device.
What is the requirement for systems with over 500 linear feet but less than 1000 linear feet? -
CORRECT ANSWER -They are only required to have a single pump.
What are the construction material requirements for dosing tanks? - CORRECT ANSWER -
Same construction materials and reinforcement requirements as septic tanks.
Can one or two piece dosing tanks be used? - CORRECT ANSWER -
Yes, one or two piece dosing tanks may be used.
How should two piece dosing tank sections be joined? - CORRECT ANSWER -
They must be joined by using mastic, butyl rubber, or other pliable sealant that is waterproof.
What is the required diameter for a water-tight access cover on dosing tanks? -
CORRECT ANSWER -At least 24 inches
