CSM Best Management Practices (BMPs) & Design 3

Question 1

Which outlet structure feature is specifically designed to remove floating pollutants such as trash and oil from a stormwater pond?

Accepted Answer

Skimmer or reverse slope pipe

Answer

A skimmer or reverse slope pipe draws water from below the surface, preventing floating debris and oils from passing through the outlet during normal operations.

Question 2

In bioretention design, what is the primary purpose of an internal water storage (IWS) zone?

Accepted Answer

To create an anaerobic zone that promotes denitrification and reduces nitrogen loads

Answer

The IWS zone creates saturated, anaerobic conditions in the lower media that support denitrification bacteria, significantly improving total nitrogen removal.

Question 3

When designing a vegetated filter strip, the recommended maximum slope to ensure uniform sheet flow and adequate treatment is:

Accepted Answer

5%

Answer

Filter strips are typically designed with slopes of 2–5%, with 5% being a common upper limit to maintain sheet flow and prevent channelization that bypasses treatment.

Question 4

A grass swale is being designed to convey stormwater while providing water quality treatment. Which parameter is most critical to verify for adequate treatment residence time?

Accepted Answer

Swale length and longitudinal slope

Answer

Swale length and longitudinal slope together determine flow velocity and hydraulic residence time, which governs the degree of settling and biological treatment achieved.

Question 5

Which factor most strongly influences the selection of plants for a bioretention facility in an arid or semi-arid climate?

Accepted Answer

Ability to tolerate both inundation and extended drought periods

Answer

Bioretention plants in arid climates experience both flooding during storms and prolonged dry periods between events, requiring species tolerant of both extremes.

(CSM) Certified Stormwater Manager Practice Test

(CSM) Certified Stormwater Manager Practice Test

CSM Best Management Practices (BMPs) & Design 3