How would an operator check a new manhole for leakage?

• A. Smoke test
• B. Dye test
• C. Pressure test
• D. Vacuum test

Answer: (D)

When checking a new manhole for leakage, a vacuum test is used. The manhole is sealed and a vacuum is applied inside; if there are leaks around joints, seals, or the rim, air will seep in and the vacuum level will drop more quickly than expected. This test is practical for manholes because it directly assesses the airtightness of the structure without filling it with water. If the vacuum holds steady within the specified limits for the required time, the manhole passes for leakage. Smoke or dye tests focus on surface or pipe connections rather than interior airtightness, and a pressure test is less common for this purpose, making the vacuum test the best choice for detecting leaks in a new manhole.