Borehole Cleaning

Public Utility Supplier

Borehole Engineering Services (BES) were recently contracted to carry out the refurbishment of two boreholes for a public Utility company in the South of England. The boreholes had suffered iron fouling in the top screened section of the borehole.

The source of water from these boreholes was taken from two aquifers, one of which had gravel in the top section of the borehole which was screened off with slotted steel pipe and the second which was chalk below the gravels which was not screened but open.

Before the main works started a step test was carried to establish current yield from the borehole.

The Large capacity borehole pumps were removed from the boreholes and a CCTV unit sent into the borehole to record its current condition. The CCTV survey discovered that the steel pipe had heavy incrustations and the open section of chalk was relatively clean. The survey also identified a foreign body in one of the boreholes which needed to be removed and the engineers on site deployed a recovery tool into the borehole to retrieve this object. The operation was a success, the object turned out to be a pump shroud which had detached itself from the borehole pump.

We added 400kg of BoreSaver chemical to each borehole and surged the chemical into the gravel pack with a cleaning brush. When this process was complete the brush was removed and any debris vacuumed from the borehole with our special equipment. The dirty water from the vacuuming process was passed through our onsite treatment plant and once clean the water was discharged into a dedicated discharge point.

A further CCTV survey was carried out and the pumps replaced. A second step test was carried out which showed that the borehole yield had improved and there was also an improvement in the water chemistry.