Locating Buried Services

Striking a buried service is the most frequent serious incident in excavation work. Electricity cables cause burns and fatalities; gas mains cause explosions; fibre and water strikes cause enormous disruption. The sequence that prevents them is always the same.

Plan, scan, dig

• Plan. Obtain service drawings from every utility and from the site's own records. Treat them as indicative only — depths and routes are routinely wrong, and unrecorded services are common on old industrial sites.
• Scan. Survey with a cable avoidance tool and signal generator, in all available modes, sweeping the area in two directions at right angles. Mark findings on the ground, and re-scan as the dig progresses.
• Dig. Break ground by hand or with vacuum excavation within the safe distance of any known or suspected service. Expose services before mechanical excavation goes near them.

Assumptions that kill

Assume every service is live until proven otherwise; assume the drawing is wrong; assume there are services nobody recorded. Where the drawing shows nothing, that is the least reliable information of all — it means nobody recorded anything, not that nothing is there.