The British Dam Society
Caring for dams, people and the environment

About Dams

Back to safetySafety - Visual inspection

A visual inspection of a dam, and its surrounding area, are an important part of a reservoir safety check. Unusual features on the face of a dam may reveal important clues about the condition of its internal body.

At embankment dams, the civil engineer looks for cracks, bulges and hollows on the downstream face and on the upstream face, when the water is low. These features could indicate that the dam is becoming unstable, and that there is a possibility that, with time, a portion of the slope could collapse, just like a landslide. Hollows can also indicate that floodwater has been overtopping the dam and gradually eroding the downstream slope. Engineers also look for signs of water leakage through or underneath the dam. Water leaking through the dam can erode away the material inside gradually creating a large cavity. Eventually, the cavity can collapse in on itself reducing the stability of the dam. Water leaking under the dam can indicate that there is a problem in its foundation.

Inspection gallery

Inspection gallery running
through a dam

Concrete dams have tunnels running through them called inspection galleries. These are just big enough for a person to walk through, so the engineer can inspect the condition of the dam inside as well as outside. The surface of the concrete is checked for deterioration and cracking. The engineer also looks for any signs that could show that the dam or sections of it are moving. Checks are also made for any leaks.

On all types of dams the condition of water pipes, valves and floodgates are checked. The valves and gates are operated regularly to check that they will work when required.