Cable percussion drilling (CPD) is one of the most popular geotechnical drilling techniques available. It’s reliable, cost-effective and the rigs can be easily transported between sites. However, they’re a tad on the large side. In more restricted spaces, such as urban city projects or basements, this can become problematic. This is when cutdown drilling comes in handy.
Here at Borehole Solutions, a leading geotechnical drilling company in the UK, we offer both regular and cutdown cable percussion drilling solutions. This week, our experts delve into the latter method.
How does CPD work?
You may be wondering what exactly cable percussion drilling (CPD) is and how it works. CPD, also known as shell and auger drilling, uses a large tripod rig and winch to lift and drop a cutting tool inside a steel casing tube. This case maintains stability and prevents the borehole collapsing from any insecure soil. The cutting tool used is dependent on the type of ground substrate.
CPD is useful for both environmental and geotechnical site investigations. Whether you’re analysing the quality of groundwater or using piled foundations to build a basement, then you will likely require cable percussion rigs to carry out the job. If you’d like to know more about CPD, check out our previous blog post here.
The size specifications of standard rigs vary, but generally, they tend to be around 6 to 6.5 metres tall. Hence their main drawback is that they’re relatively cumbersome and can only be used in open and good access conditions. If this isn’t the case for your site, then this is when cutdown rigs are extremely useful!
How Big are Cutdown Drilling Rigs?
The main difference between regular CPD and cutdown drilling rigs is the height. Furthermore, the cutdown rigs feature a telescopic mast, which allows you to adjust the height to suit specific requirements. These rigs can be as short as two metres, making them ideal for restricted and limited access drilling jobs.
For example, we recently had a project in London, where building height was a challenge. With our cutdown rig, however, we were able to drill 40-metre-deep boreholes and return high-quality samples, despite the rig’s small frame size.
Cutdown rigs also feature smaller component parts, meaning it can be set-up more easily on-site. Furthermore, the parts can be transported to and from different sites effortlessly. Overall, cutdown drilling is a highly effective technique for where drilling needs to be carried out, but space comes at a premium.
Contact Borehole Solutions
If you’re interested in hearing more about our cable percussion and cutdown drilling services, then get in touch today! We also offer a multitude of other geotechnical drilling services too; including sonic drilling, window sampling and soakaway installation, to name but a few.