CTQP Drainage Systems Inspection 2

Question 1

What is an 'inlet' in a storm drainage system?

Accepted Answer

A structure that collects surface runoff and directs it into the underground pipe system

Answer

A drainage inlet is a structure (curb inlet, grate inlet, junction box) that collects surface water and channels it into the underground storm sewer system.

Question 2

What is the minimum longitudinal slope required for storm drain pipes to maintain self-cleaning velocity?

Accepted Answer

0.50%

Answer

A minimum pipe slope of approximately 0.5% is generally required to maintain a self-cleaning velocity of about 2.5 feet per second in storm drain pipes.

Question 3

What is a 'French drain' or 'underdrains'?

Accepted Answer

A subsurface perforated pipe system that collects and removes groundwater or infiltrated water

Answer

Underdrains (French drains) are subsurface systems using perforated pipe surrounded by filter aggregate to intercept and remove groundwater that would otherwise weaken the pavement subgrade.

Question 4

What does 'hydraulic gradient' refer to in storm drainage design?

Accepted Answer

The slope of the energy line in a pipe system under pressure or gravity flow

Answer

The hydraulic gradient is the slope of the pressure or energy line through a drainage system, and must remain below the rim of manholes and inlets to prevent surcharging.

Question 5

When inspecting a reinforced concrete pipe (RCP) joint, what is the inspector checking for?

Accepted Answer

Proper gasket installation, joint gap, and alignment between pipe sections

Answer

At RCP joints, the inspector verifies that the rubber gasket is properly seated, the joint gap is within tolerance, and the pipe sections are properly aligned without offsets.

CTQP - Construction Training & Qualification Program Practice Test

CTQP - Construction Training & Qualification Program Practice Test

CTQP Drainage Systems Inspection 2