11
The shut off valve is then opened suddenly, allowing the pressure to reach the cutting
tool. The cutting tool cuts the zip ties, releasing the spring-loaded platens against the
borehole walls (Figure 13).
Figure 13 - 4500MLP Post-release
If installed in drill casing:
The sensor is lowered to the proposed elevation and the casing is pulled just above this
elevation before the assembly is released. The cutting tool is then removed from the drill
hole and the next assembly is prepared for installation.
When lowering the subsequent piezometers down the hole, feed the cables from the lower
piezometers through the middle of the assembled piezometer rather than around the
outside. (This will prevent the cables from interfering with the filter contacting with the
borehole wall).
When all the assemblies are installed, the hole can be grouted from the bottom up using
bentonite cement grout.
