Rotary drilling is a core technique used to investigate deep or dense subsurface conditions as part of Geotechnical and Geo-Environmental ground investigations. It allows for the collection of soil and rock strata samples, or the formation of deep boreholes for monitoring and testing. This drilling method is specifically used where penetration is required through very dense soils, hard layers and bedrock, enabling engineers to understand the structural and geological conditions beneath a development site.Rotary drilling works by advancing a borehole using a combination of impact energy and rotation. Our rigs can be track-mounted or lorry-mounted, allowing access to a wide range of sites including open land, restricted areas and challenging terrain. These rigs deliver high levels of torque, rotation and drilling power, enabling effective progress through difficult ground conditions.
The rotary cutting head rotates at high speeds (typically 50–120 rpm) and is capable of cutting through both hard rock and softer materials. Due to the friction generated by rapid rotation, cooling and lubrication are required—typically using air, water, or drilling mud, depending on the site conditions.
Rotary drilling provides essential data used to support interpretive reports for a wide range of design and engineering purposes, including:
Phase Ground Investigations delivers rotary drilling services throughout the UK using trained drillers, experienced engineering geologists and modern equipment.
Rotary drilling is divided into two main methods depending on the purpose of the investigation: Rotary Core Drilling and Rotary Open-Hole Drilling.
Rotary core drilling is used when continuous rock cores are required for detailed examination. This method retrieves intact cylindrical cores that allow engineers to investigate rock strength, structure, fractures and bedding.
It is commonly used where developments may involve:
Cores are extracted via an internal barrel and brought to the surface using a wireline recovery system. Once retrieved, the cores are photographed, logged and stored in secure core boxes.
All cores are logged by experienced geologists in accordance with the relevant British and European standards, including:
Samples from core drilling may undergo a range of laboratory tests, such as:
Rotary open-hole drilling is used when rapid progression is required and intact rock cores are not necessary. Instead of retrieving continuous cores, the drilling proceeds quickly to reach a particular depth or geological feature.
It is ideal for:
Rotary open-hole drilling is frequently used on former mining land or sites where the presence of voids, shallow workings or instability must be assessed.
Rotary drilling plays an essential role in a wide range of intrusive ground investigation activities. It can be used alongside, or in combination with,
other techniques such as:
These techniques provide a complete picture of the site’s geotechnical and environmental conditions.
All drilling work is carried out in accordance with strict health and safety procedures. Before work begins,
Phase Ground Investigations completes:
We work across a wide range of development types and manage every aspect of the investigation—including design, supervision, drilling, sampling, monitoring and reporting.
Phase Ground Investigations completes:
We believe high-quality investigations come from expert supervision, accurate logging and robust interpretation, not just the equipment used. Our team applies current standards, Eurocodes and industry best practice across every project.
If you’re planning a development, assessing a brownfield site, or concerned about radon levels in an existing property, we’re here to help.