Auger drill
An auger is build op from round central drill rods. Those drill rods could be hollow. Around the central rod a wide steel spiral is present. The drilling is done by putting pressure on the rod when placing it on the ground and start spinning in the right direction. During the drilling the augur jacks the drilled soil up. The auger drill technique can be used in several ways, described below.
A full auger drill in an open borehole
This will result in an average indication of the soil structure. During the drilling a strongly mixing of soils take place, this even becomes more when the depth increases. Indicative sampling or profile description is only possible with shallow drilling. De worst smearing is present at the outer layer of the soil sample. When using this method of auger drilling the outer layer of the soil sample needs to be removed before an indication can be made.
This technique can’t be used with soil who is contaminated and in research to contaminated soil. The risk is very great that with this technique the ground water or the soils beneath the contaminated soils will overcome the same as its upper layers. The only exception for this is when the soil is heterogenic contaminated and when contamination is only present in the upper soil.
Conditions use full auger drill in an open borehole
| Parameters | Present |
|---|---|
| Contaminated | Yes |
| Heterogenic contaminated | Yes |
| Debris | No |
| Accurate description | No |
A full auger drill in a tubed borehole
The difference with the method described above is that this technique prevents the auger drill from mixing with its surrounding soils and this concludes in a reasonable sample. This sample can give a good indication of the soil structure. Due to the use of a tube there is a little to no smearing with this technique.
Conditions use full auger drill in an open borehole
| Parameters | Present |
|---|---|
| Contaminated | Yes |
| Heterogenic contaminated | Yes |
| Debris | No |
| Accurate description | Yes |
An hollow auger drill
The auger is hollow when there is a pin or a hatch present at the bottom of the auger which can be removed. Due to the fact that the spiral width is not in proportion with the diameter of the drill, the surrounding soil is very repressed, a big amount of smearing takes place and the soil structure can’t be interpreted. A monitoring well can be placed inside the hollow part of an auger drill to take samples during drilling.
Auger systems aren’t very accurate especially not for contaminated soils, because they spread to much of the contaminated substance. They are useful for soils which contain much debris, for example on a landfill or dump.
Conditions use hollow auger drill
| Parameters | Present |
|---|---|
| Contaminated | Yes |
| Heterogenic contaminated | Yes |
| Debris | Yes |
References
- NPR 5741:2014
