Why Do I Need A Trial Pit?

by | Jan 17, 2022

When a construction project is proposed, before anything can begin it must first be determined whether construction is even feasible! This requires scrutiny of the ground conditions and soil composition; often done by excavating a trial pit. Simple, cost-effective and commonplace in the construction industry for years, it’s no surprise that Borehole Solutions have dug them out countless times.

So, if you’re pondering the question ‘Do I need a trial pit?’, look no further, because the Borehole team have the answers!

But What Actually Is A Trial Pit?

To put it simply, they are pits between 1 and 4 meters deep. Whilst often dug by hand, a small digger may be used for a larger pit. Structural measures must be used for any pit deeper than 1.2 metres, to ensure it’s supported should someone enter it. If electricity cabling, gas pipelines, or the like and known to be beneath, then it’s essential that excavation is carried out by hand!

Okay, But What Are The Benefits?

Knowing exactly what a trial pit is is all well and good, but it doesn’t really answer the question of ‘Do I need a trial pit?’. Well, read on to discover the benefits!


As previously mentioned, trial pits are incredibly simple; coming in as the most practical site investigation method offered by a geotechnical drilling company. With this in mind, it goes without saying that you won’t need to spend too much!

The type of equipment typically used – namely, the lack of machinery – saves on the cost of fuel and transport. Plus, as the pit is so simple to dig, one working day is all it will take to carry out the work. This, again, saves on potential transport costs.

Solid Results And Flexibility

If you’re still not sure if you do need a trial pit or not, perhaps the following will help.

Both disturbed and undisturbed samples can be taken following a trial pit excavation. Further to this, a variety of sampling methods can be facilitated too! This includes, but is not limited to, contamination tests, infiltration tests and vane shear tests. An initial soil strata profiling will also be possible following a trial pit excavation. Despite being carried out at such an early stage, the results will still be fairly comprehensive, not to mention essential for potential contractors!

In the effort to hammer the point home, both vertical and lateral subsurface samples can be taken; providing yet another benefit. All the above really epitomizes the versatility of what, at first glance, is simply a hole in the ground.

It doesn’t take much effort to conduct real-time changes to the sampling strategy of the trial pit, either. This is ideal as the overall site plan won’t require a drastic overhaul. Furthermore, any trial pit dug by hand will typically be reinstated once the sampling has been carried out, if requested.

Contact Borehole Solutions

An investigation like trial pitting is basically a geotechnical company’s bread and butter. Helping to provide clients with the information they need in a quick and efficient manner, trial pits provide the basis on any further, more complex drilling methods that may be necessary.

If, despite the blog, you’re still asking yourself ‘Do I need a trial pit?’, then please give us a call! You can reach Borehole Solutions on 01733 200 501, email at info@boreholesolutions.com, or use our online contact form.