In sandy or silty soils the probes can be installed vertically - preferably in a small angle contrary to the direction of the main water flow. It is important that the drilled hole fits together with the probe's shaft diameter to prevent preferential water flow along the shaft. Especially in clayey soils any cavities must be filled with a paste of fine soil material or sealed with Bentonite. In clayey soils it might be recommendable to use cladding tubes for depths below 80 cm so the probes can be removed when the clay dries out. Please consider that holes in clayey soil might last for hundreds of years operating as a water course.
 
 
 
 
 
 

The installation from a profile pit has the advantage that the natural soil bed and horizons are not disturbed by vertical probes. But it is important to keep enough distance to the pit's wall! The more clayey a soil is the further deep the probes have to be inserted horizontally and the more important it is to refill the drilled hole properly. If possible the pit itself should be refilled following the soil's natural compactness of the packing. Try to create an interlocking of wall and refilling. To avoid horizons with too compact packing randomly pound layers (for example with your boots) and then loosen the layer's surface with a rake.