CSM CSM Urban Stormwater Systems & Infrastructure

Question 1

What is a combined sewer overflow (CSO) and why is it a stormwater concern?

Accepted Answer

A CSO occurs when a combined sewer system carrying both sewage and stormwater exceeds capacity, discharging untreated waste to waterways

Answer

Combined sewer systems carry both sanitary sewage and stormwater in one pipe; during heavy rain, excess volume overflows to receiving waters as untreated sewage mixed with stormwater, posing significant water quality and public health risks.

Question 2

What distinguishes a detention pond from a retention pond in stormwater management?

Accepted Answer

A detention pond temporarily holds runoff and releases it slowly after a storm; a retention pond permanently holds a standing pool of water

Answer

Detention ponds (dry ponds) temporarily store runoff to control peak flow and drain completely between storms, while retention ponds (wet ponds) maintain a permanent pool that provides additional water quality treatment.

Question 3

What is an impervious surface and how does it affect the urban stormwater runoff cycle?

Accepted Answer

A hard surface that prevents infiltration, increasing runoff volume, velocity, and peak discharge compared to natural land

Answer

Impervious surfaces such as roads, rooftops, and parking lots prevent rainfall from infiltrating into the soil, dramatically increasing the volume and peak rate of stormwater runoff and the pollutants it carries.

Question 4

What is the function of a storm drain inlet grate in an urban stormwater system?

Accepted Answer

To collect surface runoff from streets and direct it into the underground storm drain conveyance system

Answer

Storm drain inlets capture surface runoff from streets and parking areas and convey it to the underground storm sewer pipe network for transport to an outfall or treatment facility.

Question 5

What is the purpose of a headwall at a storm drain outfall?

Accepted Answer

To stabilize the end of a pipe where it discharges to a channel or receiving water and to prevent erosion around the outlet

Answer

A headwall is a concrete or masonry structure that supports and protects the end of a storm drain pipe at an outfall, preventing embankment erosion and scour around the pipe outlet.

(CSM) Certified Stormwater Manager Practice Test

(CSM) Certified Stormwater Manager Practice Test

CSM CSM Urban Stormwater Systems & Infrastructure