KDOT Drainage & Storm Water Systems 4

Question 1

What is the purpose of a storm water detention basin in a highway right-of-way?

Accepted Answer

To temporarily store runoff and reduce peak discharge rates

Answer

Detention basins temporarily store storm water to attenuate peak flows, releasing water at a controlled, lower rate to downstream channels.

Question 2

During inspection of a roadside ditch, you notice the ditch lining has separated from the soil and is undermined. What condition does this indicate?

Accepted Answer

Piping or subsurface erosion beneath the ditch lining

Answer

Separation and undermining of ditch lining indicates subsurface piping or erosion where water has moved soil from beneath the lining.

Question 3

What is a 'subdrain' and what is its primary function in highway drainage?

Accepted Answer

A perforated pipe or aggregate trench that removes subsurface water from pavement layers

Answer

A subdrain is a subsurface drainage system using perforated pipe or aggregate to intercept and remove groundwater or perched water from pavement base layers.

Question 4

When inspecting a concrete pipe culvert joint, what defect is most critical to document and report immediately?

Accepted Answer

Joint separation with visible soil infiltration or exfiltration

Answer

Joint separation allowing soil migration indicates potential pipe collapse, embankment failure, or sinkhole formation, requiring immediate reporting.

Question 5

What is the KDOT-required minimum slope for roadside ditches to ensure adequate self-cleaning velocity?

Accepted Answer

0.3%

Answer

KDOT generally requires a minimum ditch slope of 0.3% to maintain sufficient flow velocity to prevent sediment deposition and promote self-cleaning.

(KDOT) Certified Kansas Department of Transportation Inspector Practice Test

(KDOT) Certified Kansas Department of Transportation Inspector Practice Test

KDOT Drainage & Storm Water Systems 4