Utility Systems Flashcards

What is the minimum cover depth required for a water main installed under a roadway in most US jurisdictions?

Answer: 36 inches

Most jurisdictions require a minimum of 36 inches of cover over water mains beneath roadways to protect against traffic loads and freezing.

During a utility corridor inspection, you observe a gas line and electrical conduit running parallel. What is the standard minimum horizontal separation required between them?

Answer: 12 inches

NFPA and most utility standards require a minimum 12-inch horizontal separation between gas lines and electrical conduits to reduce hazard risk.

A sewer main inspection using CCTV reveals root intrusion rated as a Grade 4 defect. What action is most appropriate?

Answer: Recommend immediate pipe lining or replacement

A Grade 4 root intrusion defect indicates severe structural compromise requiring immediate rehabilitation such as lining or pipe replacement.

Which type of valve is most commonly used to isolate sections of a water distribution main for maintenance?

Answer: Gate valve

Gate valves are the standard isolation valve in water distribution mains because they provide full-bore flow and reliable shut-off when fully closed.

When inspecting a stormwater detention basin, which condition indicates the outlet structure is functioning improperly?

Answer: Water level above the emergency spillway during a design storm

Water exceeding the emergency spillway elevation during a design storm indicates the outlet structure cannot pass design flows, posing a dam-safety risk.

What does a negative pressure reading in a sanitary sewer manhole most likely indicate?

Answer: A blocked downstream pipe

Negative pressure (vacuum) in a manhole typically results from a downstream blockage restricting airflow and creating a suction effect.

During a telecom conduit inspection, a mandrel test is performed. What is the primary purpose of this test?

Answer: Confirm conduit internal diameter is unobstructed

A mandrel test uses a rigid cylinder slightly smaller than the conduit ID to verify that no obstructions, deflections, or joint offsets will impede cable installation.