CEPSCI Sediment Basin and Trap Design

Question 1

What is the primary purpose of a temporary sediment basin on a construction site?

Accepted Answer

To capture and retain sediment-laden runoff, allowing sediment to settle out before water is discharged

Answer

To store construction materials

Answer

To provide drinking water for construction workers

Answer

To store stormwater for irrigation

Question 2

A sediment basin is typically required for drainage areas exceeding:

Accepted Answer

5 acres

Answer

0.5 acres

Answer

10 acres

Answer

50 acres

Question 3

The wet storage volume in a sediment basin is designed to:

Accepted Answer

Hold the accumulated sediment load between cleanout events

Answer

Provide habitat for aquatic species

Answer

Store clean water for reuse

Answer

Provide surge capacity during large storm events

Question 4

The outlet structure of a sediment basin should be designed to:

Accepted Answer

Release water slowly from the upper portion of the pool where the water is clearest while retaining the sediment-laden lower water

Answer

Release all captured water as quickly as possible

Answer

Prevent any water from leaving the basin

Answer

Allow sediment to pass through with the water

Question 5

Surface area is critical in sediment trap design because:

Accepted Answer

Larger surface area allows more particles to settle per unit time by lowering the overflow rate

Answer

Surface area should be ignored

Answer

Only depth matters for sediment trap design

Answer

Only the outlet pipe size matters

Question 6

When should a temporary sediment basin be cleaned out?

Accepted Answer

When sediment accumulation reaches 50% of the designed wet storage volume

Answer

Only when it is completely full

Answer

After every rainfall event

Answer

Never; basins are designed to fill completely