Derg Water Treatment Works, Castlederg

Lowry Building & Civil Engineering harnesses its knowledge and experience of the water industry to deliver a high-quality build supplying a daily 26 million litres of water…

An award-winning, first-of-its-kind pilot plant is among innovations introduced by Northern Ireland Water (NI Water) and Lowry Building & Civil Engineering Ltd (LBCE) to develop the design for a £12m upgrade of Derg Water Treatment Works (WTW).

Commissioned by NI Water, the project was ready for beneficial use on schedule in March 2023 and is now supplying a daily 26 million litres of high-quality water to Castlederg, Strabane and part of the Omagh area.

It adds to the existing works built in 2002, with a new clarification process and activated carbon addition offering enhanced water treatment.

Having worked with NI Water for many years, the firm harnessed its knowledge and experience of the water industry and its processes to deliver a high-quality build, with construction commencing in May 2021.

The pioneering pilot plant achieved an Institute of Water Innovation Award and has since been reconfigured for use at several other NI Water locations. The new-build Derg WTW was then shortlisted for a CEF Infrastructure Award 2023.

As well as processing 2-methyl-4-chlorophenoxyacetic acid and trihalomethanes, the solution improves herbicide and organics removal.

Jemma Catterson, Business Development at LBCE, said, “Working collaboratively with NI Water, LBCE developed an innovative mobile pilot plant to test myriad water treatment options so that the most effective and efficient treatment solution could be executed at the Derg WTW and future NI Water capital works programmes.

“The pilot plant was set up to replicate the water or wastewater treatment process, allowing the rigorous testing of different carbon-based products and through real-time data collection and analysis.

“This pilot plant ran for nine months, and the data was used to assist the design/contractor team to deliver the best solution for this location.”

Having selected clarification using liquid-activated carbon as the best solution, LBCE worked collaboratively with the client and project manager to deliver the infrastructure on time and to budget.

The project included construction of a new building matching in with the existing structure, and a cofferdam 5m below ground, with 1700m3 of concrete, 214T of reinforcement steel and 96T of structural steel used during construction.

“The impressive site set-up was established, maintained and managed perfectly and the project required extensive concrete pours to create large tanks and structures and, consequently, to ensure working-at-height safety when constructing around these tanks and structures using bespoke platforms,” said Jemma. 

“Under our ISO14001 accreditation procedures, we meticulously monitored our environmental performance, proactively meeting stringent waste targets. Our water, fuel, electricity use, and subsequent carbon emissions were all strictly monitored and reduced.

“The works area was situated adjacent to the existing WTWs. Therefore, extreme care and precaution was taken to ensure minimal disruption to this essential service throughout the works and comprehensive planning to ensure the switchover was completed with no interruption to public water supply.”

Mitigation measures had to be introduced to address the onsite presence of badgers and invasive species Himalayan Balsam.

“Our team worked tirelessly to deliver exceptional ISO9001 build quality while adapting to changing requirements, for example dosing and storage of treatment chemicals were adjusted to suit revised client requirements,” said Jemma.

“Innovative methods for supporting wall reinforcement as part of the temporary works were implemented and prefabrication of formwork and reinforcement which improved safety and programme.”

LBCE has delivered a 30% increase in capacity, reduced wash water consumption improvement in turbidity figures to 0.5 NTU and extended runtime for primary filters.

“This project is special to LBCE as it is a few miles from our head office and brought a large-scale infrastructure improvement to our local area, in addition to many jobs provided for our staff and local supply chain throughout the construction period,” said Jemma.

“It was a mixture of heavy civil engineering activities and building, which is where we really provide excellence with a multidisciplinary team.”

Client: Northern Ireland Water
Main Contractor: Lowry Building & Civil Engineering (as part of DLG Joint Venture)
NEC Project Manager: RPS Consulting UK & Ireland
Civil/Structural Designer: McAdam

Lowry Building & Civil Engineering Ltd (LBCE)
7 John Street, Castlederg BT81 7AW

To read the full feature on Derg Water Treatment Works, Castlederg go to NIBuilder 35-1 Feb-March click here