Precision drilling Services standard pneumatic test equipment is available to suit different size boreholes and can be configured to single or straddle configurations to test large or more specific zones.
Single Pneumatic Test Equipment is designed for testing cored holes whilst drilling progresses to greater depths. The pneumatic system is suitable for testing cored holes to a total depth of 600m. Below this depth, Hydraulic Permeability Test Equipment must be used.
When a zone of interest is identified in the retrieved core sample, the drill rods are moved back a suitable distance, such that the deployed packer equipment can be inflated above the zone of interest.
Once inflated (using the Nitrogen gas supply), testing of water injection flow rates at various injection pressures can commence. Injection pressure can be controlled via a bypass system on the injection flowmeter board – supplied as part of the standard equipment.
Straddle Pneumatic Test Equipment is designed for testing specific zones of cored holes once drilling to total depth is complete. The pneumatic system is suitable for testing cored holes to a total depth of 600m. Below this depth, Hydraulic Permeability Test Equipment must be used.
When a zone of interest is identified in the retrieved core sample, the drill rods are moved back a suitable distance such that the deployed packer equipment can be inflated with the two packers straddling the zone of interest. Once inflated, testing of water injection flow rates at various injection pressures can commence. Injection pressure can be controlled via a bypass system on the injection flowmeter board – supplied as part of the standard equipment.
Other methods of Permeability testing can be conducted using the falling head and rising head technics.
Permeability can be determined by undertaking in-situ tests in boreholes or standpipe piezometers. The test method involves variable head (rising or falling) or constant head procedures and requires knowledge of the groundwater level. The type of test undertaken depends on the soil type a variable head test would be carried out in relatively permeable soils and a constant head test in less permeable material.
When a permeability test takes place in a borehole, the water can flow either directly into (or out of) the soil or a perforated pipe with a gravel surround can be installed if required, to maintain the stability of the borehole and the water level can be measured via the pipe.
The test measures the permeability (k) of the soil below the groundwater level i.e. in the saturated ground and because it is carried out in situ provides a more reliable result than can be determined in the laboratory.Implementation of the test and interpretation of the results requires the experience of the various test techniques and knowledge of the site ground conditions.
On some sites there may be a large local variation in permeability, for example due to horizontal layers of soils with differing permeability or discontinuities such as fissures. In this situation larger scale pumping tests can be carried out, where the water levels are measured in an array of boreholes around a central borehole from which groundwater is pumped, and the permeability is established.
With experience in all aspects of Exploration, Geotechnical, Environmental drilling, and Hydro and Water Well Drilling, we are here to look after our clients in a professional, ethical, and reliable manner, while maintaining safe, environmentally responsible practices.
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