Borehole tests are also carried out using the Flexible Liner Underground Technologies (FLUTe). FLUTe methods are used to estimate hydraulic properties in boreholes, seal fracture flows and sample groundwater. For transmissivity profiling, we estimate the transmissivity from the change in flow rate as the blank liner seals off flow paths as it advances in the open hole.
Borehole pump and slug testing are conducted to determine aquifer hydraulic properties, for example hydraulic conductivity and transmissivity, and test well performance. In Borehole pump tests, water is pumped out of a borehole at a controlled rate and the aquifer response in terms of recharge response (drawdown) is measured. In slug tests, the water level in the borehole known as the control well can be made to fall, that is, water is pumped out of the well so that the measurements are taken as the water rises in the well. We call this a rising-head test. Another way is to quickly raise the water level in the well and then take measurements as the water level falls. This is called a falling-head test. Pump and slug testing measurements can be made in observation wells or in the control well. Different types of pump tests include recovery test where measurements are only made after pumping has been terminated, constant-rate tests where pumping in the control well is maintained at a constant-rate throughout and step-drawdown tests where constant pumping rate at the control well is sequential.
Groundwater monitoring wells are drilled to obtain groundwater samples. They can either be permanent or temporary and can be drilled in a variety of geologic formations that dictate what drilling method will be appropriate for what formation. Monitoring wells can be drilled using a host of methods including direct push, rotary drilling and augering.
Monitoring wells drilled using direct push technology can range in diameter from 12 to 50 mm and instead of bringing cuttings out to the surface, they compress them to the sides of the borehole wall. Direct Push monitoring wells don’t typically go deeper than 50 ft but they can get to significant depths on some occasions. DP technologies are typically used in unconsolidated formations.