Thames bats for nature

A nitrate removal project has earned Thames Water an award because of its choice of building materials and its consideration of local habitats, including a colony of bats. Shan Kelly reports

Excellent environmental design and project management at a new WTW near the picturesque village of Lambourn in Berkshire has earned Thames Water a silver medal from the Institution of Chemical Engineers.

The £4.1M nitrate removal project was completed in February by a Thames Water project team, which involved civil contractors Gleeson Construction Services and process engineers Christ Kennicott Water Technologies (CKWT). The new Ashdown Park WTW was designed by Thames Water in partnership with Gleeson Construction Services, English Heritage and the Vale of White Horse District Council to blend into their environment. Construction of the new WTW, housed within a timber-framed building, took just nine months, there were no accidents, and the whole project was under budget.

Thames Water took pains to ensure the building works caused the minimum environmental impact, by taking great care in its choice of building materials and by protecting local animal habitats. The team allowed the dead tree trunk seen in the picture to remain right next to the works because it is home to a colony of bats.

Thames Water project manager Adrian Jack said: “We have used the latest technology at this plant, and we have been able to dramatically improve water quality in West Berkshire and Oxfordshire.

“Thames Water is continuously striving to improve water quality for all our customers so we are delighted to have won recognition for our efforts from Institution of Chemical Engineers. This investment will benefit customers in Oxfordshire and West Berkshire for years to come.”

The project began because a rise in nitrate levels was observed in water sources at Fognam Down and Ashdown Park, in Oxfordshire. The levels are thought to result from farming activities in the area and were deemed a potential threat to public health. Instead of building two separate plants, the design team decided to pursue a lower-cost option of replacing the plants at Fognam Down and Ashdown Park with one new plant at Ashdown Park, which is 1km from Fognam Down.

Water from the Fognam Down borehole is now taken to Ashdown Park for treatment and then returned via a new pipeline. New pipelines also link the plant to the villages of Ashbury and Lambourn and to the wider Thames network, so they have an emergency water supply.

CKWT supplied the Ashdown Park WTW with the first Rohm and Haas Advanced Amberpack nitrate removal system fitted in the UK.

Thames Water chose the Amberpack system because it is simple to operate and maintain, it uses components that are readily available, and it produces the smallest possible waste stream volume. The Amberpack system minimises the use of chemicals and produces low waste volumes while operating at efficient levels because of its fractal distribution system.

This last factor was important because the plant is in a remote location without a direct sewer connection, and operates fully automatically. It is run with just occasional visits from operational staff. CKWT began work in February 2005, designing, supplying, fitting and commissioning a 3.59Ml/d (149.6m3/h) advanced Amberpack Ion Exchange Plant, as well as ancillary equipment and electrical controls.

CKWT has since installed similar systems at Mid-Kent Water and Southern Water through its exclusive licence agreement with Rohm and Haas, and is working on projects for Wessex Water and Severn Trent Water.

GleesonConstruction Services is one of Thames Water’s framework partners. It designs and constructs treatment works in Thames’s Western provinces area, which includes areas outside the M25.

“We’ve been working with Thames for eight years, so it is nice to get this recognition,” said Paul Lloyd Henry, a director of GCS after hearing the project was runner up in the ICE Water award. The Institution of Chemical Engineers Water Award recognises excellence in the sustainable use of water resources. The 2006 awards were presented by writer and broadcaster Adam Hart-Davis at the Banqueting House in London’s Whitehall last month.

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