Borehole Cleaning and Maintenance > Borehole Cleaning Process

Our services are tailored to meet your borehole cleaning requirements. Below is an example of a five-stage process we can undertake to achieve maximum efficiency and optimum results.

This whole process is project and site managed by our skilled and experienced team. Not every stage is needed for all clients and our experts will advise what your require in the consultation process.

Stage 1 – Condition assessment and removal of loose items

Before conducting the clean, lost items are removed from the base of the borehole to not hamper the process.

What’s at the bottom of your borehole?
Pump cables, pvc stilling tubes, rising main sections or borehole pumpsets. Various recovery tools are used to retrieve lost items. Each tool is modified to suit the existing circumstances. A CCTV camera is used to assist the process.

Stage 2 – Cleaning process

  • All materials will be removed from the borehole walls.
  • Using a nylon or steel brush, loose materials will be dislodged from the borehole walls. The brush will be lifted up and down several times to ensure effective removal.
  • Different diameter brushes will be used to ensure all casing and screens are cleaned.
  • All loose material collects in the base of the borehole.

Stage 3 - Air Lifting Operation

Following brushing all loose materials are removed by air lifting.

  • API tubes with an air injection pipe fitted to the base are lowered into the borehole just clear of the sediment.
  • High pressure air is then injected in the API tubes and water forced upwards.
  • The flow induced collects loose material from the borehole and the water/sediment is collected in the settlement tank.
  • All fine material, stones, chalk lumps etc can be removed in this way. The only restriction to the size of material removed is the diameter of the air lift pipe.
  • All material deposited in the settlement tank is removed by sludge tanker.
  • Following air lifting, a CCTV survey is carried out to assess the effectiveness of the operation.

Stage 4 - Acidising Operation

Following air lifting, acid can be gravity fed into the borehole to supplement the cleaning operation. This usually improves borehole yield.

  • API tubes with a brush fitted are lowered into the borehole and 32% strength Hydrochloric Acid is gravity fed.
  • The brush is then raised up and down to ‘swab’ the acid through the screen tubes and into the gravel pack behind.
  • The acid reacts with iron and calcium deposits which helps to remove ‘blinding’
  • Encouraging acid through the gravel pack and into the aquifer is beneficial to improving borehole yield.
  • Following an overnight period to allow the acid to react, the borehole will be air lifted to settlement tanks to remove all acidic water.
  • The water will then be neutralised using lime and removed from the tank with a sludge tanker.
  • Further airlifting will take place to ensure all traces of acidic water are removed.

Stage 5 – Project completion

Following acidising, the pumping plant will be reinstalled into the borehole.

Pumping to waste is conducted to get the water quality to optimum levels

If required, turbidity levels are reached and samples are taken.

Once water samples are clear, the borehole will be returned to service, now running at peak performance and efficiency.

As part of South Staffordshire Plc, we can also assist you with any pump efficiency or replacement requirements you have through our experts at IWS M&E. Click here to read more.