Effective water well rehabilitation using a combined ultrasonic-mechanical method

Abstract

Abstract Background The restoration of original boreholes is preferable to building new ones as the process is more cost-effective. However, traditional chemical or mechanical regeneration methods may cause soil contamination or destruction of the borehole equipment. Materials and methods Here, we report on a newly developed ultrasound device that has been designed to reduce the need for the heavy lifting equipment, such as cranes, that typically accompany commercially available equipment. The device is minimized in size and equipped with a PLC, allowing the unit to be controlled remotely using a laptop computer. We tested the prototype ultrasound device on a fifty-year-old borehole and used standard geophysical well-logging techniques to evaluate its regeneration efficiency. Results After regeneration the fundamental change was an increase in the intensity of the downward flow, the water no more flows across the borehole, but exclusively downward (Q=115,000 l/day) what was thirty-fold acceleration of the flow of water through the well. New tributaries to the well were activated, which also signalled cleaning of the formerly clogged gravel sheath. The specific yield derived after regeneration was 1.13-1.49 fold higher than the specific yield before regeneration. Conclusion Borehole regeneration using ultrasound, while a less widely used method, offers adequate regeneration efficiency and is more environmentally friendly. Moreover, the presented prototype also offers reduced financial costs for regeneration compared to similar techniques that currently use heavy equipment and enables better mobility for harder-to-reach wells.