CESSWI Stormwater Management Practices 2

Question 1

Which type of detention basin is designed to drain completely between storm events, providing no permanent pool of water?

Accepted Answer

Dry detention basin

Answer

Dry detention basins (also called dry ponds) temporarily store runoff and drain completely between storms, providing only flood control without water quality benefits from a permanent pool.

Question 2

What is the primary purpose of an extended detention basin compared to a standard dry detention basin?

Accepted Answer

Provide longer residence time to settle fine sediments

Answer

Extended detention basins hold runoff for 24–40 hours, allowing finer sediment particles that would not settle in a standard detention period to be removed before release.

Question 3

A bioretention cell (rain garden) treats stormwater primarily through which combination of processes?

Accepted Answer

Filtration, infiltration, and biological uptake

Answer

Bioretention cells use engineered soil media for filtration, underlying native soil for infiltration, and plants for biological nutrient uptake to achieve pollutant removal.

Question 4

Under the NPDES Construction General Permit, what minimum rainfall threshold typically triggers the requirement to inspect a construction site for BMPs?

Accepted Answer

0.25 inch

Answer

Most NPDES Construction General Permits require post-storm inspections following rainfall events of 0.25 inch or greater within a 24-hour period.

Question 5

Which outlet structure configuration is best suited to control two separate design storms (e.g., 2-year and 100-year) from a single detention basin?

Accepted Answer

Riser with multiple orifices at different elevations

Answer

A multi-stage riser with orifices at different elevations independently controls smaller, more frequent storms at lower stages and larger storms at higher stages.

(CESSWI) Certified Erosion, Sediment, and Storm Water Inspector Practice Test

(CESSWI) Certified Erosion, Sediment, and Storm Water Inspector Practice Test

CESSWI Stormwater Management Practices 2