Bristol Water has a major water treatment works where the operation relies upon ozone tanks which are key to the purification process. There is usually an empty tan,k so when maintenance is required they can isolate the tank and use the empty one while works are carried out.

Due to the discharge gate valves leaking, water from the Granular Activated Carbon (GAC) filters was flowing back into the tanks. Selwood’s specialists were called in because not only did the customer need the tanks emptied, but also the water from the GAC filters which was flowing back in.

The challenge

The work presented several challenges, including the short time frame allowed for the job to ensure minimum disruption to the treatment works.

The only position where the tanks could be pumped from was at the top – but the roof of the tanks would not bear the weight of any pumps being placed there. The other challenge was that because it is a clean water site, submersible pumps were not an option.

Once the job was finished, any pipework would need to be removed immediately so that the Bristol Water maintenance team could have access.

There was a need to allow around four hours for the tanks to be purged and cleared, and to be able to act quickly in the event of any breakdowns overnight.

The solution

The decision was taken to run the pumping operation to empty the tanks overnight to minimise disruption during the day. Selwood’s solutions team constructed a large scaffold ramp which was used to help install suction pipework on the roof of the chambers.

Seven brand new Selwood S160Eco pumps, coupled with lengths of blue wire armored clean water pipework, were used to drain the tanks in an operation that began at 3am and ended at 7am.

A qualified Selwood fitter, equipped with multiple spare parts, was on site overnight in case of any breakdowns or issues.

When the pumping was complete, “A” frames and electric hoists were needed to lower and remove the pipework quickly to allow access.

The result

The whole job was completed within five days from delivery of pumps and pipework to installation, site checks, pumping process, deinstallation and collection of equipment.

The planning, hard work and timing of Selwood’s teams, working closely with Bristol Water, meant the operation was carried out quickly and efficiently, enabling the customer to get workers into the tanks at the first opportunity once the pumping operation was complete.

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