What is a trial trench, and who orders it?
A trial trench is a check, not construction. You dig a small hole exactly where a pipe or cable might run, look at it, confirm the depth and route, then carry on with your main work. Contractors order trial trenches before drilling or piling for a new building, a bridge, a tower, or even a cycling track. Heitmann Middle East runs dry suction excavators from Abu Dhabi and is the official partner of RSP, the German suction excavator maker in Saalfeld, since 1993. On construction sites, trial trenches are the standard first step before piling.
The bore that hit the airport fuel line
Here is a real industry incident. A subcontractor drilled a 1.5 m diameter bore - wide enough to stand in - straight into the kerosene supply line of Abu Dhabi Airport. No one had checked what was under that ground. A simple trial trench would have shown the pipe and stopped the drill before it touched fuel. This is why the check comes first: damaged pipelines and cables cost millions, and every hour of shutdown adds more.
When do you need a trial trench?
You need one whenever you are about to put something hard and fast into the ground and you are not 100% sure what is already down there.
- Before drilling or piling for a building, bridge, tower, or foundation.
- Before a new road, footpath, or cycling track cuts across old ground.
- When utility drawings are old, missing, or do not match the site.
- Near a refinery, fuel line, or power cable, where a hit is very costly.
- When your HSE plan asks you to prove what is underground first.
How does it work on site?
- Locate. We mark where lines may run, using your drawings and any site scans.
- Expose with air. The dry suction excavator pulls the soil out with airflow - fan technology, no water, no slurry, no cutting blade near the pipe.
- Verify. The pipe or cable is now open to view. You confirm the exact depth and route.
- Hand over. The trench is clean and ready for your survey, drilling rig, or piling crew.
Why does it protect buried lines?
A digger bucket or an auger can slice through a pipe before anyone sees it. Air cannot. That single difference is why suction is the safe way to look underground. If your job is pipe-focused, see our pipeline exposure service; to rent a machine with a trained operator, go to suction excavator rental.
- Protection of underground infrastructure: air lifts soil away and cannot cut a live line.
- Worker safety: no worker stands in the trench while it is dug - the operator uses a radio remote control.
- Lower manpower cost: one machine and one operator replace 100-150 workers with shovels.
- Speed: suction digging is up to 8x faster than manual digging.
- German technology: built on RSP suction engineering from Saalfeld, Germany.
| Point | Trial trench first | Blind drilling |
|---|---|---|
| Risk to buried lines | Pipe or cable is found and exposed first | Drill or pile can hit an unknown line |
| Speed | Small check, up to 8x faster than manual digging | Fast until it hits something, then all work stops |
| Cost logic | One machine, one operator, low manpower | Damaged pipelines and cables cost millions |
| Downtime | Short, planned check | Unplanned shutdown and repair |
Is it safe near fuel and refinery areas?
Yes. The machine is Zone 2 certified for high-hazard and refinery sites. It carries an on-board gas warning system with two sensors and automatic shutdown, an earthing and grounding system so there are no sparks, a spark arrestor, and a Chalwyn valve. Full detail is on the suction excavator safety page.