Barhale awarded £21M West London shaft upgrade scheme for Thames Water ring main

Barhale has been selected by Thames Water to deliver a £21M strategic investment for the water company’s ring main in West London.

The Mogden Pump Out Shaft scheme will upgrade the existing inspection shaft on the Thames Water ring main, a vital fresh water artery running beneath London.

Once operational, the Mogden Pump Out Shaft will be able to supply the whole of Thames Water’s Hampton area, which includes parts of West London, Kingston-Upon-Thames and Twickenham postcodes. The scheme is being brought forward to add additional water supply resilience to the West of London as it will be able to operate at close to normal operating pressure in the event of a failure at Hampton Pump Out Shaft. More than 300,000 people take their water from the local network fed by Hampton Water Treatment Works.

Four 350 kW VSD pumps will be installed in the Mogden shaft with each pump being capable of delivering a peak flow of 36Ml a day to give a combined 108Ml a day from any three of the pumps. They will be capable of being “turned down” to meet current and future minimum night flows.

A new pipeline will be connected to the existing Kew 838mm main to the north of the site and a new surge column, surge tank, additional surge vessels and control panel will be installed on the outgoing connection.

Barhale will also install a 2 x 3.8mva HV metered supply power supply, drawing from a network independent of that used by Hampton Pump Out Shaft, to provide additional protection from electrical supply failure.

The Mogden Inspection Shaft is located in a separate compound in the North West corner of the Mogden Sewage Treatment Works site. The scheme will increase the footprint of the Thames Water ring main shaft compound to contain all new buildings, kiosks and ancillary equipment. A new cover will be installed over the 38m deep shaft.

Barhale water director Shane Gorman said: “At 7m the Mogden shaft is a narrower diameter than the 10m typical for a pump out shaft, so our design has had to reflect the reduced available space.

“Additionally, this is a clean water solution located within a sewage treatment works site so we have to put in place measures to mitigate and prevent any potential for cross-contamination.

“We do have the advantage of significant experience of the shaft and the ring main dating back more than 30 years.

“Recently, we have completed extensive inspections and replacement of the white caps along the two sections of the Thames Water ring main from the Kempton shaft to the Mogden shaft, 7km, and from the Mogden shaft to the Kew shaft, 5km.

“We are very pleased that Thames Water has chosen us for this important strategic investment which will provide crucial reinforcement for the water supply in West London.”

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