A portion of the sewer installed under an obstruction in which sewage is pushed under the obstacle is called what?

• A. Energy Grade Line
• B. Inverted Siphon
• C. Offset Invert
• D. Interconnected Sewer

Answer: (B)

An inverted siphon is the pipeline section that carries sewage under an obstacle by dipping the pipe below the barrier so the flow continues under gravity from upstream to downstream. The sewage is effectively pushed through under the obstacle by the hydraulic head, reemerging on the other side. This setup is used to cross roads, streams, or other obstructions while keeping the sewer flowing in a continuous grade. The other terms don’t describe a crossing beneath an obstacle: the energy grade line is about head losses along the system, an offset invert refers to changing the invert level to fit the route, and interconnected sewer describes network connections rather than the crossing method.