We also provide a qualified and experienced engineer to supervise a cable percussion rig or window sampling rig, whilst logging soils to BS5930 and taking representative soil samples. If you require any of these rigs for your site investigation, we would be happy to arrange this from one of our approved contractors. Logs, installation details and lab results are then appended to a factual report and provided to the client.
Window and Windowless Sampling
Window and windowless sampling is a method of ground investigation that involves driving hollow steel tubes through the ground via a high frequency percussive hammer. Causing minimum disturbance, the rig is relatively small and usually mounted on rubber tracks making it very suitable for sites with restricted access.
Sample tubes are usually 1 metre long and have a window down one side of the barrel for window sampling techniques. Windowless sample techniques have an inner plastic liner that is removed, cut open and inspected. Barrels come in different sizes, allowing the hole to taper with depth. Standard Penetration Tests are also carried out at certain intervals to give soil strength data.
Cable Percussion Drilling
Cable Percussion Drilling (Shell and Auger) is one of the most popular techniques of ground investigation in the UK. This cable winch operated rig, usually towed by a four-wheeled drive vehicle, is larger than a window sample rig but can reach depths up to 50 m. The winch is used to pull up a clay cutter, a bailer or a chisel and is then released, letting the weight of the tools penetrate through the soil. Casing is driven into the ground in non-cohesive soils to prevent borehole collapse. Standard Penetration Tests are also carried out at certain intervals to give soil strength data.
‘Fantastic service. Microgeotechnical’s ability to complete tasks with absolute precision is consistently impressive. They are always willing to go above and beyond for the job in hand whilst providing excellent communication throughout.’
Catherine Riley / Senior Chartered Geo-Environmental Engineer / NPS Property Consultants Ltd