(Also known as Uncontamined Bedrock Sampling)
Specially designed cutterheads are used to drive through overburden to a bedrock horizon. Rods are added in 1 metre increments to the desired depth. An insitu, uncontaminated sample is then recovered which enables geologists to pick changes in rock type, mineral type etc. with pinpoint accuracy.

Depending on cutterhead size, this system delivers a sample of between 200 grams and 500 grams. Invaluable in areas with deep overburden cover and where transported or contaminated soils are a problem.

There are two power heads used in "Wacker" drilling - the light weight two-stroke motor with manual recovery and the hydraulic system which has approximately double the drive power, and where the rods are pulled hydraulically.

When used in Civil Engineering the penetrating 'Shut Off' point for a 30mm drill string is about the same as an average sized excavator, which is most useful when pre-determining overburden depths for pipelines etc. This can allow the contractor to cost accurately for hard rock trenching or examine alternative routes.
Also an excellent tool for peizometer installations.