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During drilling operations, and in constructing the well itself, it is important to ensure that the aquifer—the underground store of water—does not become polluted. This is reinforced by the fact that EC directives, and provisions in the new Food Act, require that water used for irrigating certain crops has strict standards of purity. To guard your water supply, we work to best industry practice. We take great care in the way we conduct our engineering work, and use only safe, non-toxic materials within the borehole. After drilling to the required depth, the borehole is lined with a well screen and casing, usually made of thermo-plastic, or stainless steel if required. Screens are precision cut to allow the full potential of the aquifer to be utilised. Screen design is engineered so that water entrance velocity is minimised—this means that any tendency to draw in sediment as water is being drawn is reduced. The annulus around the screen is then packed with a rounded inert silica gravel or sand, acting as a filter. Towards the top of the borehole, resting on the silica, a grouted seal closes the drill hole to the pipe. This extends the full length of the ‘overburden’—loosely described as soil or broken ground—down as far as the impermeable layer, to a minimum depth of 3m into a competent rock head. It's purpose is to prevent surface water—which may be polluted by, for example, animal faeces—entering your borehole. When the grout is cured, a sealed chamber is installed which houses the well head and surface valvery. Finally, a reliable stainless steel submersible pump, powered by electricity, solar power or wind, is lowered into the borehole, which brings water to the surface under pressure. At this point, a water sample is taken for laboratory analysis. In most cases the water is fine for immediate use, and needs no additional treatment, but if this should be necessary, we will install filters to ensure that the water is potable. |
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