In-situ or Field Testing
Groundwater and Gas Monitoring
Groundwater monitoring is carried out in order to obtain samples for testing or to monitor the water levels. The groundwater samples are recovered using either a dedicated disposable hand held bailer or a mechanical down-hole submersible pump.
Gas monitoring is undertaken to determine the levels of methane, carbon dioxide, oxygen and other gases which can be generated by made ground or backfilled materials. The gas flow within the borehole is dependent on the atmospheric pressure at the time the readings are taken.
Insitu California Bearing Ratio (CBR) Testing
The CBR test is normally used for road, runways or car park pavement design to assess the strength of the sub-grade. The test involves driving a cylindrical plunger of a defined area into the soil at a uniform rate. This requires the use of a reaction load, (usually a four wheel drive vehicle), to provide the force. Alternatively a profile of equivalent CBR can be measured using the Dynamic Cone Penetrometer (DCP).
Plate Bearing Testing
Plate bearing tests involve jacking a plate of known dimensions against a reaction load, usually the underside of a tracked excavator and recording the ground deformation. Different tests are used to assess the bearing capacity of the soil and the prediction of settlement characteristics. The modulus of sub-grade reaction can be measured and correlated with CBR which is useful for assessing gravelly material when a normal CBR test is inappropriate.