The Rotary Pacific Water for Life Foundation (RPW) team spent two days in the settlement of Cobue in Bua Vanua Levu to retrieve a submersible pump that got stuck in a borehole. A few months ago a routine maintenance operation had gone wrong, leaving the pump locked in the well at 27m below ground level.
Some individuals within the community had tried to pull the pump out but to no avail. To make matters worse the electrical power supply and water level probe cables had ruptured and got entangled in the 4 inch bore.
RPW went on site with a CCTV borehole inspection camera and custom made tools. Different sized hooks fitted on drop pipes were lowered into the well to untangle and extract the electrical wiring. With the aid of the CCTV borehole camera, a precision operation under water was possible, even at a depth of 27m below ground.
After two days of determined fishing in the bore, the RPW team succeeded in removing all the electrical cables as well as the pump from the well casing.
It is suspected that scale formation had caused the problem. Thick deposits of precipitate were observed on the pump and drop pipe.
Scaling can occur when ground water has high levels of minerals like calcium carbonate present in it. It is also highly likely that the well has been drilled in calcium rich deposits. When water is pumped from the well, changes in pressure and temperature occur creating ideal conditions for minerals to precipitate or settle out. This causes scale formation on the casing, liner and screens of the well
Without remediation, scale formation on the screens will eventually reduce the yield of the well up to the point that the well will have to be abandoned. RPW will look in to a management strategy that includes mechanical brushing and acid treatment of the well.