Before you dig: utility surveys on UAE sites

Every excavation in the UAE starts with the same question: what is under here? The usual answer is a set of utility drawings obtained from the relevant authorities. That is a starting point, but treating it as a complete answer is how sites hit cables.

Why the drawings are not enough

Underground services in a developed area belong to several different owners. In Dubai that means DEWA for power and water, du and Etisalat for telecoms, the municipality for sewer and irrigation, and district cooling providers on top. Each maintains its own records, in its own format, to its own standard of accuracy.

Those records are drawn from what was designed or what was recorded at the time of installation, which is not always what was built. Services get diverted around obstructions during construction. Abandoned runs stay in the ground and stay on the drawing. Depths are frequently approximate, and ground levels change afterwards through regrading and resurfacing, so a service recorded at 1.2 m may now sit at 600 mm.

Overlay drawings from four authorities and they will not agree with each other. The survey is what resolves the contradictions against physical reality.

What a GPR ground survey actually does

We survey the dig area with the Proceq GS8000, pushing a survey cart over the ground in a grid pattern and reading reflections from buried objects. The result is a map of what is physically beneath the site — power cables, water and sewer lines, telecom ducts, gas pipes, tanks and voids.

Findings are marked directly on the ground surface where the excavation crew will actually see them, and issued as a survey report. For larger sites we provide marked-up drawings, and data can be delivered in CAD or GIS formats where the project team works that way.

The important distinction is that GPR finds objects, not records. It will locate an abandoned duct nobody documented and a service that was diverted during construction, because it responds to what is there rather than what was written down.

Depth: what the ground allows

Working depth is typically 3 to 5 metres, and the soil decides which end of that range you get. This is the part of ground scanning most often oversold, so it is worth being precise about.

• Dry sand — the best case. Inland sites in Al Quoz, Dubai Investments Park and the Sharjah Industrial Areas can read past 5 m.
• Compacted fill — generally good, depending on what the fill contains.
• Wet or clay-heavy ground — signal attenuates faster and depth drops.
• Sabkha with saline groundwater — the hardest condition for radar. On Abu Dhabi Island and coastal strips this can pull achievable depth below 3 m.

Depth in ground is decided by the soil, not by marketing. If your excavation goes deeper than the ground lets us read, you should know that before you dig rather than after.

This is why we quote 3–5 m as a realistic working range and assess the actual conditions on site. A survey that reports clean results to 5 m in saline sabkha is not a better survey — it is a less honest one.

What a strike actually costs

The repair bill for a severed cable is rarely the largest number. Hitting a live power cable is first a safety event, with genuine risk of serious injury to the operator. After that come the consequences:

• Loss of supply to everything downstream, which may include buildings well beyond your site
• Emergency attendance and reinstatement charged by the utility owner
• Stop-work while the incident is investigated
• Programme delay across every trade behind the excavation
• Potential liability for third-party losses caused by the outage

Against that, a pre-excavation survey is a small, predictable cost incurred before anything can go wrong.

Two different instruments

Ground scanning and concrete scanning get conflated constantly, and they are separate jobs. The GS8000 images the ground to find buried utilities before excavation, reaching 3–5 m depending on soil. The GP8000 images the inside of concrete to find rebar and post-tension cables before cutting, reaching up to 1 m in concrete.

They are different machines built for different tasks. We operate both, which means the right radar goes to the right job rather than one instrument being stretched across both and doing neither well.

A workable sequence

Obtain the utility records from the authorities, then survey the dig area and reconcile the two. Mark the findings on the ground, agree the excavation limits and identify anything that must be hand-dug. Then excavate to that map, treating the survey as live guidance rather than a document filed at the start.

Because we run both the scanning and the excavation, there is no gap in responsibility between the survey and the dig — the crew excavating is working to a map produced by the same company that will answer for it.