Simple and economic measurement of groundwater pressures in soil and rock can be carried out using Casagrande type piezometers. Geosense® piezometers are made up of low air entry porous plastic or ceramic elements which are connected to standpipe tubing and lowered into a predrilled borehole. Alternative types may be driven or pushed into soft soil.
Where Casagrande type piezometers are being installed then the porous element is surrounded by filter sand and a Bentonite seal placed above this response zone.
Water level measurements are normally taken using a water level meter (dipmeter) or in the case of artesian pressure a Bourdon pressure gauge is attached to the top.
Standard piezometer tubing is supplied as threaded 3/4” BSP or plain for gluing and is coupled together using separate BSP sockets. Alternative options include flush threading and sizes up to 2” which are used mainly for open standpipe piezometers. Tubing is available in high strength ABS, PVC or galvanised steel for drive-in piezometers in 3, 2 and 1 meter lengths.
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Material: HDPE (porous plastic element); Alumo silicate (ceramic element)
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Mean pore size: 60 microns
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Permeability: 3 x 10-4 m/s
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Porosity: 35% (porous plastic element); 45% (ceramic element)
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Tip diameter: 27-50 mm
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Tip length: 200-1000 mm
