Other Sevices
Dams and Reservoirs Ltd is able to offer a unique method of tracking and plotting individual leakage paths, whether that be leakage from dams or tailings facilities, flows into deep excavations including mines, construction excavations including tunnels and caverns and chambers, and also trace flows from tips and landfills where pollution is being caused. Willowstick can also be used to identify the best position to make drillings for water production from aquifers.
Because individual leakage paths can be identified if remedial works are required, they can be targeted achieving significant savings
Willowstick Technologies, LLC has developed a unique geophysical imaging technology specifically designed to quickly and accurately identify, map and model preferential seepage flow paths through, beneath, and around earthen embankments. Like an angiogram that enables medical personnel to identify the flow of blood inside the human body, the Willowstick technology is able to render two-dimensional (2D) maps and three-dimensional (3D) models of seepage flow (see Figure 2).
Willowstick Method Designed Specifically for Groundwater Characterization
Angiogram
Willowstick
Figure 2 – Angiogram / Willowstick Comparison
Willowstick’s technology is built upon several scientific principles that need to be made clear in order to understand our methodology. Please note that all the following statements need to be taken together in order to adequately understand the Willowstick methodology:
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Subsurface water seeping through earthen materials increases the electrical conductivity of the earthen materials through which it flows. Without water, earthen materials are fundamentally electrical insulators while earthen materials saturated by subsurface water flow become excellent electrical conductors. For example, the electrical conductivity of dry earthen materials typically ranges between 10-12 and 10-17 mho/m. However, in-ground measurements of groundwater conductivity typically range from 10-1 to 10-8mho/m—in other words many orders of magnitude higher.
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Whenever an electrical circuit is established a magnetic field is also created. The magnetic field emanates from the electric current. The specific characteristics of the magnetic field are determined by the Biot-Savart Law.
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The electric current follows the preferential groundwater flow path or the path of least resistance to complete a circuit between two electrodes.
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Measuring magnetic field intensity is an accurate method to determine zones of highest conductivity or transport porosity of water, or water bearing zones.
Over the past 16 years Willowstick has used these principles to build innovative instruments that identify, track and model the intensity of the signature magnetic fields generated on-site. We then load the hundreds of thousands of data points we collect into Willowstick’s proprietary software and models to determine the preferential flow path(s) of subsurface water. Willowstick’s patented hardware and software combine all the readings generated, filter out the noise, and generate models of the subsurface. These models allow us to identify preferential groundwater flow paths and patterns as our signature current spreads beneath the site of the investigation.
Our algorithms compare the magnetic field intensity, as observed by the Willowstick instruments, to the expected magnetic field for an electrically homogeneous subsurface environment. We then compare differences between the observed readings and the computer-generated model of expected readings by calculating a ratio between the two values. This highlights differences between the observed value and the expected value thus revealing preferential groundwater flow paths.
To define an even higher level of precision and resolution in our generated images, Willowstick has developed a series of proprietary 3D inversion models that collect and invert the data in such a way that the patterns become more readily apparent at depth. These models enable us to clearly identify the coordinates and depth of the groundwater flow paths. The result is a series of slices combined into a multi-dimensional model similar to the way Magnetic Resonance Imaging (MRI) instruments present their results to radiologists and physicians.
Willowstick has been used extensively in the UK by Thames Water, United Utilities, Scottish Water, Yorkshire Water, and Severn Trent Water and has been used by clients in Hong Kong, China, Austria, Nigeria, Norway , Sweden and South Africa
Please contact Dr Andy Hughes on 0044 7341 338092 or andy.hughes@willowstickuk.com for further information or to obtain a quote.