What is the invert elevation of a pipe?

Answer: C — The elevation at the lowest point inside the pipe

The invert elevation of a pipe refers specifically to the elevation at the lowest point inside the pipe. This measurement is critical in hydraulic and civil engineering, particularly for the design and analysis of drainage systems, sewer systems, and other types of piping where the flow is influenced by gravity. Establishing the invert elevation helps ensure proper drainage and flow characteristics, enabling engineers to determine the slope of the pipe and ensure that fluids travel effectively through the system without backflow or stagnation. While other options might relate to different aspects of pipe design or installation—such as the highest point, the elevation of ground above the pipe, or an average along its length—none accurately capture the specific definition of invert elevation as it is customarily used in engineering contexts.