How to Dig a Trench: DIY vs Hiring a Mini Excavator with Operator
Digging a trench by hand for anything beyond a short garden run is slow, hard on the body, and easy to get wrong on depth or alignment. This guide covers what trench excavation actually involves, how to dig and backfill one with a mini excavator, and how to decide between doing it yourself and hiring an operator.
Key Takeaways:
- Trench excavation is the process of digging a defined channel in the ground for services like drainage, plumbing, electrical conduit or irrigation.
- A mini excavator can dig most residential trenches in a fraction of the time it takes by hand, and no licence is required to operate one.
- Calculating the volume of a trench before you start helps you plan spoil removal and backfill material, and avoids nasty surprises halfway through the job.
- DIY trenching suits straightforward, accessible jobs, while hiring an operator makes sense for tighter access, deeper trenches or when you’d rather not run the machine yourself.
What Is Trench Excavation?
Trench excavation is digging a long, narrow channel in the ground to a specified depth and width, usually to install or access underground services. Common uses include stormwater and drainage lines, plumbing and water pipes, electrical or data conduit, irrigation, and footings for fences or retaining walls.
Trenches are typically defined by three measurements:
- Length: The total distance the trench needs to run.
- Width: Wide enough for the pipe, conduit or footing, plus working room.
- Depth: Set by the trade or plan, since depth requirements vary by service type and local regulations.
How Do You Dig a Trench With a Mini Excavator?
Digging a trench with a mini excavator involves marking the route, checking for underground services, then digging in controlled passes to the required depth and width. A mini or micro excavator with a narrow bucket gives a clean, consistent trench line without the manual labour of digging by hand.
- Mark the trench route: Use paint or pegs to mark the exact line and width before digging starts.
- Locate underground services: Contact your local utility locating service to check for existing pipes, cables or conduit along the route.
- Set up the machine: Position the excavator so it can work along the trench line without repositioning constantly.
- Dig in controlled passes: Take shallow, even passes rather than trying to hit full depth in one go.
- Check depth regularly: Measure as you go, since depth requirements from your trade or plan need to be accurate, not approximate.
- Stockpile spoil close by: Keep excavated material close to the trench line if it’s being reused for backfill.
- Trim and clean the trench: Square up the base and sides once you’ve reached the required depth.
Underground services are the biggest risk in trenching. Always confirm locations before digging, even for shallow garden trenches.
How Do You Calculate Trench Excavation?
Calculating trench excavation means working out the volume of soil that needs to be removed, which is length multiplied by width multiplied by depth. This figure tells you how much spoil you’ll need to manage and how much backfill material you’ll need if you’re not reusing the original soil.
| Trench Size | Formula | Example Volume |
|---|---|---|
| 10m long, 0.3m wide, 0.5m deep | 10 x 0.3 x 0.5 | 1.5m³ |
| 20m long, 0.4m wide, 0.6m deep | 20 x 0.4 x 0.6 | 4.8m³ |
| 30m long, 0.3m wide, 0.8m deep | 30 x 0.3 x 0.8 | 7.2m³ |
Keep in mind that excavated soil expands once it’s dug up, known as bulking, so the volume of spoil to remove is usually 20 to 30% more than the calculated trench volume.
How Do You Backfill a Trench With an Excavator?
Backfilling a trench with an excavator means placing material back in layers and compacting each one, rather than pushing all the spoil back in at once. Backfilling too quickly is one of the main reasons trenches sink or settle unevenly months later.
- Confirm the trade has finished: Don’t backfill until your plumber, electrician or relevant trade has installed and checked the service.
- Add a bedding layer if required: Some services, like pipes or conduit, need a sand or fine material bedding layer before backfill starts.
- Backfill in layers: Place material back in stages of around 150 to 200mm at a time.
- Compact each layer: Use a plate compactor or the excavator bucket to firm each layer before adding the next.
- Finish to grade: Bring the final layer up to match the surrounding ground level.
Trenches backfilled in one pass without compaction almost always settle and create a visible dip within the first year.
DIY vs Hiring an Operator: Which Should You Choose?
DIY trenching suits straightforward jobs with good access and no complications, while hiring an operator makes more sense for tighter access, deeper trenches or when you’d rather hand the machine work over entirely. Both options get the trench dug. The right one depends on your access, timeline and how comfortable you are running the machine yourself.
| Factor | DIY with Dry Hire | Wet Hire with Operator |
|---|---|---|
| Experience needed | None, no licence required for mini excavators | None, the operator handles the machine |
| Best for | Straightforward trenches with clear access | Tight access, deeper trenches, or no time to learn |
| Time commitment | You run the machine yourself | An experienced operator completes the job |
| Spoil handling | You manage stockpiling and removal | Often handled as part of the quoted job |
If you’d rather send through photos and have a local operator handle the digging and backfill, Diggermate’s Trenching Services team can quote the job based on your access and trench requirements.
Whether you dig it yourself or hire an operator, getting the depth, backfill and service locations right is what separates a trench that lasts from one that needs redoing. If you want the machine work handled without hiring equipment yourself, Diggermate’s Done For You service can take care of the whole job.
If you’d rather have an experienced operator handle the digging and backfill, Diggermate’s Trenching Services team can quote the job based on your access and trench requirements.
Not Sure Whether to DIY or Hire an Operator?
You don’t need to work it all out before getting in touch. Tell your local Diggermate what you’re planning, what needs to be dug and what access you have on site.
They can help you work out what size machine may suit the project and whether Dry Hire makes sense if you’re happy to operate the machine yourself, or Wet Hire with an experienced operator may be the better option for the job.
Find your local Diggermate and have a chat about your project, the equipment you may need and the best way to get it done.
