Soil or tailings samples are normally the most critical data acquired in a geotechnical survey. These samples help to identify exact soil compositions through laboratory testing, as well provide the most reliable engineering strength analysis. They are used to help validate both CPTu and VST soil strength data, and are the primary source for the soil descriptions of any stratigraphic layering.  Soft material samples are collected by HELIX robots using a piston sampler and stored on board the robot in a sample magazine. The sampler is driven into the ground using the rack and pinion mechanism and the depth is measured and controlled by the on board computers. The coordinated downward movement of the tube and actuation of the piston draw a sample into the chamber. The collected material is extruded into 2 L plastic pails in the sample magazine. Up to ten pails are held in the circular magazine. Multiple samples from the same location can be added to a single pail to increase the retrieved material volume. Other soil and tailings samplers are available depending on material consistency and difficulty to access the location.