Environmental Engineering Reference
In-Depth Information
Figure 5.30.
Packer permeability testing; single packer and double packer methods.
The length of test section depends on the nature of the rock defects and the type of
structure under investigation. Examination of the drill core usually indicates the presence
of typical fracture spacing which represents probable background permeability and
anomalous structural features which may be associated with zones of higher permeability.
Test sections should be selected to provide an indication of the relative width and per-
meability of these zones. In many cases water flow may be concentrated through a few
fractures. The water loss is averaged over the length of the test section and, if the section
is too long, the presence of a high permeability zone may not be recognised.
Usual test section lengths range from 3 m to 6 m but the length may be increased in
essentially unfractured rock. When a particularly high water loss is recorded it is good
practice to repeat the test over a shorter section of the hole to further define the zone of
high permeability.
5.14.4
Test equipment
The equipment required for water pressure testing includes:
-a packer to seal the test section;
-a water line from the packer to the supply pump;
