CESSWI Sediment Control BMPs 4

Question 1

Which of the following is a PRIMARY design consideration when sizing a sediment basin outlet structure?

Accepted Answer

The outlet must handle the 10-year peak flow without overtopping the embankment

Answer

The outlet structure must safely convey the peak flow from the design storm (commonly 10-year) to prevent embankment overtopping and basin failure.

Question 2

What is the function of an anti-seep collar on a sediment basin riser pipe?

Accepted Answer

To stop water from migrating along the pipe through the embankment

Answer

Anti-seep collars interrupt the flow path of water that could migrate along the outside of the outlet pipe through the embankment, preventing piping failures.

Question 3

In which scenario is a rock berm PREFERABLE to a silt fence for sediment control?

Accepted Answer

Concentrated flow conditions or in drainage channels

Answer

Rock berms can handle concentrated flow and higher flow velocities that would overwhelm and breach a silt fence, making them more appropriate for drainage channels.

Question 4

What is the typical maximum spacing between rock check dams in a drainage channel to ensure continuity of sediment capture?

Accepted Answer

The downstream dam crest elevation should equal the toe elevation of the upstream dam

Answer

Check dams should be spaced so that the elevation of the crest of the downstream dam equals the elevation of the toe of the upstream dam, creating a level pool between them.

Question 5

Which factor MOST affects the long-term effectiveness of a sediment basin in removing fine particles?

Accepted Answer

Hydraulic residence time — the longer water stays in the basin, the more settling occurs

Answer

Fine sediment removal depends on particle settling velocity and the time water remains in the basin; longer residence time allows finer particles to settle out.

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

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

CESSWI Sediment Control BMPs 4