Typical Investigations performed by use of
GeoN Groundwater Technology
Permanently installed filter tips/extension pipes for water sampling at waste deposits. Plastic (polyethylene) tips/filters/pipes are used in order to minimize the risk for contamination. Installation is performed by pre-drilling, e.g. solid/hollow stem auger drilling or casing. Water sampling is performed 4-6 times per year. Even very small changes of the groundwater quality are easily and quickly detected.
Installation through contaminated soil layers by use of a hydraulic pusher. The filter tip is removed directly after sampling and the hole is tightened with bentonite or concrete in order to avoid cross contamination between soil layers or aquifers. GeoN Groundwater Tip of stainless steel (”heavy duty” filter tip with a protected filter) is used together with extension pipes of steel (special CPT rods or casing).
Pore pressure measurements
Measurements in order to check the state of consolidation in clay areas. Filter tips are usually installed in “pore pressure stations”. Such a station usually consists of 2-4 filter tips, installed at different levels in the cohesive soil, and of open pipes, installed in permeable soil layers. The pore pressure values are compared with the water level in the open pipes. Measurements are usually performed 2-4 times per year. One single equipment can be used for the measurement. This is the traditional way of using the GeoN Pore Pressure meter.
Pore pressure logging in low stability areas as a part of a landslide warning system. Filter tips are installed in thin permeable layers in the cohesive soil in order to detect critical pressure levels. One transducer is installed in each filter tip. Transfer of pore pressure data by GSM/Internet. Two-way communication, issuing a warning when a critical level is reached (e.g. by SMS).
Water level measurements
Measurements in open systems such as wells, drilled holes, mineshafts and lakes. The transducer is fixed at a level below the lowest level possible. The water pressure at the transducer level is measured in “meter of water column”. Data can be stored by using the read-outs Pi30/Pi301 as loggers or can be transferred by GSM/Internet as described above for pore pressure data (Bergsäker Avanet).
Insitu measurements in tight, constructed soil layers at waste deposits. The test purpose is to confirm that the permeability is according to the stipulated demands, that the soil layer is tight enough to prevent contaminated water from reaching the aquifer.
Insitu measurements in natural cohesive soil layers regarding the characteristics of consolidation.
Insitu measurements in order to calculate how fast a contaminant, dissolved in the groundwater, can be spread.