Standpipe Piezometers offer a simple and economic method for measuring water pressures in soil and rock. The Standpipe Piezometer (also known as a Casagrande Piezometer) is used to monitor piezometric water levels in vertical boreholes.
The Standpipe Piezometer typically comprises two parts: at its lowest point is a porous piezometer tip; connected to the tip is a riser pipe which continues upwards out of the top of the borehole.
To measure the borehole water level, the filter tip zone is packed with sand and then backfilled above. To isolate pore water pressure at the filter tip, a bentonite seal is required between the sand filter zone and the backfill.
Alternative filter tip types may be driven or pushed into soft soil, and different tip designs are available to suit various types of ground.
- Porous plastic or ceramic filter tip
- Choice of PVC or galvanised steel riser pipe Drive-in tip available
- Used when monitoring piezometric water levels in vertical boreholes
- Can measure artesian pressures using a Bourdon Gauge readout
- Simple, low cost system
- Ideal for routine site investigation
- Excellent long term reliability
Water level indication is measured with a water level meter.
Measuring artesian pressures requires a Bourdon Pressure Gauge to be connected to the top of the standpipe. The Standpipe Piezometer is capable of measuring the borehole water level or water pressure at the piezometer tip.
The water pressure at the filter tip is derived by measuring the height of the water surface in the riser pipe above the piezometer tip. This is achieved by installing a bentonite seal in between the sand filter zone and the backfill.
For measuring the borehole water level, no bentonite seal is required, but measurements are taken in the same manner.
Typical applications include monitoring pore water pressure and water levels in soil or rock, such as:
- Determining the stability of embankments, dams and reservoirs
- Stability investigations of natural and cut slopes
- Control of de-watering and drainage operations
- Monitoring seepage and groundwater movements
- Monitoring of water table and aquifers
- Pollution and environmental studies
- Construction control of shallow underground works
- Permeability measurements