Characteristics

Pulse tools are used in non-cohesive soils under the groundwater table. The borehole is protected from collapsing by tubing. The soil under the tube is released and taken with the help of the pulsing. The hand pulse is used for shallow drilling until a depth of at most 10 metric meters and is used in combination with hand drills. The pulse tools come in a light and a heavy variant. The light variant is used for drilling from 5 meter to 30 meter underground and the mechanical heavy pulse tools are used for drilling from 10 meters.

After use of the pulse tools there are some samples present in the tool which allow for a decent soil description, but you should take into account that these samples are highly mixed. Thin peat- or clay layers are often present as large pieces in the liquid sand.

When using this technique, water is removed from the borehole. This could lead to swelling of the soil material inside the tube. To counter this water of drink quality is added. The use of this water needs to be measured and reported. The level of added water never may exceed the ground water table.

References

• NPR 5741:2014