When a pipe slope drain discharges to a sediment trap or basin, where must the outlet discharge?

The correct choice is that the outlet of a pipe slope drain must discharge at or above the wet pool elevation of the sediment trap or basin. This is important because discharging at or above the wet pool elevation helps ensure that the sediment-laden water enters the sediment trap or basin effectively. It prevents any potential short-circuiting of the flow, which can occur if the discharge point is too low, leading to inefficient sediment capture.

Maintaining the discharge at or above the wet pool elevation allows the water to spread out and thus slows down the flow velocity, allowing suspended particles to settle out of the water column more effectively. This design consideration is crucial for maximizing the sediment trapping efficiency of the sediment trap or basin, thereby aiding in effective erosion and sediment control on construction sites or areas undergoing land disturbance.