Massive reservoir project uses floating pump station

Massive reservoir project uses floating pump station

The Abberton Reservoir near Colchester, England, plays a strategic role in supplying drinking water to 1.5 million people in Essex. When the already enormous reservoir needed to be expanded to meet growing demand, a solution was needed to keep the water supply pumping while the existing pumping station was rebuilt. Xylem’s Rental Services devised the perfect temporary pumping solution.

Abberton Reservoir, situated on the outskirts of Colchester in the scenic Essex countryside, is a large freshwater reservoir covering over 660 hectares. The reservoir is owned and operated by Essex & Suffolk Water (ESW), part of Northumbrian Water Group.

In order to meeting growing demand for water and protect against drought, ESW decided to enlarge the capacity of the reservoir. The £150 million project would ensure Abberton Reservoir could not only capture and store an increased volume of water, but also to provide a secure supply of water for many years into the future.

A huge civil engineering project

Starting in 2010, the expansion of the Abberton Reservoir was England’s biggest civil construction project outside the Olympic Park. Prior to its expansion, the reservoir already held 26 billion liters of water. After completing the project, and raising the height of its main dam by 3.2 meters, it could hold 41 billion liters.

The expansion work also included demolishing and reconstructing the main pumping station, which is responsible for pumping water to the local treatment works.

To keep the water pumping from the reservoir during the project, a new temporary pumping station was built alongside the existing station. This allowed contractors to demolish the original pumping station and build a completely new, raised pumping station upon the footprint of the original.

A floating pontoon with Flygt pumps

Construction of the temporary station gave rise to a number of challenges. It had only one draw-off level and, should there have been a drought, the available water could have been below that of the station. Furthermore, its location adjacent the reservoir bank made it more susceptible to high turbidity and water quality issues.

Rental experts from Xylem devised a plan to build a purpose built, floating pontoon, which would house their Flygt submersible pumps and be positioned in the center of the reservoir to draw the best quality water available at any level, with minimal silt content. The pontoon would be guided out into the center of the reservoir and then anchored down on each corner, to ensure it remained in prime position on the water.

Xylem Rental installed four Flygt NS3301 pumps within the floating pontoon. Three of the Flygt pumps were for regular pumping duty, with the fourth installed as a standby pump for periods of heavier pumping requirements.

Efficient pumping with variable frequency drives

Over 300 meters of heavy duty pipe were laid to connect the pontoon to the temporary pumping station. Flygt variable frequency drives were installed in the station, to ensure optimal running of the pumps and the most efficient pumping possible. The rental solution from Xylem meant that the main pumping station could be decommissioned and work could begin on this significant part of the expansion works.

“The project at Abberton Reservoir has been a huge success,” says Mick Boyle, Rental Manager at Xylem UK. “The installation Xylem provided enabled ESW to continue to supply water to their supply region as usual, and highlighted our ability to design bespoke temporary dewatering systems and ensure that our customers achieved the end result they desired.”

The new Abberton Pumping Station is now fully operational and the expansion project is complete. The level of the reservoir has been raised by a total of three meters, which will eventually lead to a sixty percent increase in the overall capacity of the reservoir.

“We were delighted with Xylem’s innovative approach to our pumping needs during this project,” says Kevin Packard, Acceptance Engineer at ESW. “The bespoke solution meant that we could continue to supply the best quality water to our customers while the new pumping station was being built.”

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by Simon