Piezometer standpipe (also called Casagrande piezometers) are widely used in the environmental and geotechnical industry for the monitoring of groundwater levels (i.e. the freatic water table) or to monitor the quality and quantity of the groundwater. Placing them is generally costly and time consuming. It is for this reason that Gouda-Geo has developed push-in piezometer filter tubes.
The direct push capabilities of the CPT penetrometer rig can be used for the placing of these push-in piezometer filter tubes. The piezometer tubes are pushed into the ground by means of 55 mm casing tubes using the pushing force of the CPT penetrometer rig.
The conical tip at the bottom of the piezometer tube assures a very straight bore hole that is slightly larger in diameter than the casing in order to reduce lateral friction on the string of tubes. This makes it possible to reach greater depths.
On reaching the desired depth the string of casing tubes can be retracted using the pulling force of the CPT penetrometer rig and the piezometer filter tube stays in place and the sampling hose connects to the surface. Backfilling of the filter tube with coarse sand is recommended.
The push-in piezometer filter tubes are successfully applied for geotechnical and environmental research, such as:
- Groundwater sampling and monitoring
- Contamination plume delineations
- Low-cost mini well points
- Monitoring of dams, reservoirs & embankments
- Slope stability
- Groundwater levels for dewatering & drainage
- Permeability testing
- Contaminated soil monitoring
The push-in piezometer filter tube composes of a cast iron conical tip, a HDPE filter tube with slots, a protective stocking (to prevent clogging) and a connector at the top for the water sampling hose that connects to the surface. The PE water sampling hose can be guided through a hose pump to collect the groundwater samples. Since the conical tip is manufactured of cast iron and the filter tube of class A HDPE it does not cause any environmental issues.