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Information and public services for the Island of Jersey

L'înformâtion et les sèrvices publyis pouor I'Île dé Jèrri

Sewage Treatment Works complete

18 December 2023

Work to build Jersey's new Sewage Treatment Works (STW) at Bellozanne is complete and the facility is now fully operational, giving more capacity to support the need for additional homes across the Island, reducing STW running costs, and giving better odour control.

The former Sewage Treatment Works, many parts of which dated back to the original construction on the same site in the late 1950s, was inefficient, difficult to maintain, provided inconsistent treatment, and could not be expanded to meet future demand.

Work began on the new STW in early 2019, and in recent years various sections have come online in a phased approach as they have been completed.

Key benefits include:

  • Capacity to deal with a connected population equivalent of 141,600 people, subject to increase in the wider sewerage network capacity to transfer the flows to the STW
  • Additional storm water storage capacity
  • More consistent control of the levels of nitrogen released into St Aubin’s Bay • Better instrumentation and control facilities
  • Reduction in operation and maintenance costs
  • Better odour control facilities

The new STW, which cost £67million, is part of a wider £83million project at Bellozanne which also includes feasibility, planning, investigations, engineering, site services, old sludge platform demolition, hillside removal and Clinical Waste Incinerator replacement.

The Minister for Infrastructure, Deputy Tom Binet, said: “This state-of-the-art new facility represents a significant step forward in the way in which we manage and treat liquid waste in the Island.

“Having recently been shown around Bellozanne, it’s clear to see it’s a remarkable piece of engineering that this exceptional team has quietly got on with, bringing it ‘in house’ to finish, ensuring Jersey has a modern Sewage Treatment Works, fit for our current and future population.

“I’ve also, this past week, secured extra funding for some of the required improvements to the wider sewerage network, which is nearing its capacity and will need expansion to cope with the much-needed additional homes. With the Sewage Treatment Works now up and running with increased capacity, it’ll be vital to focus on the Island-wide infrastructure so we can support housing needs.”

UK construction company NMCN, who in April 2018 were awarded the main design and construction contract, carried out the initial phase of the STW, but went into administration in 2021. The Infrastructure and Environment department stepped in as the principal contractor, with the in-house team leading the project through to today’s completion. Despite the change to the delivery model, the project has been delivered within the allocated budget.

Duncan Berry, Head of Liquid Waste, added: “The successful completion of this major new piece of infrastructure is a testament to the collaborative efforts of the team over many years.

“We’re already seeing much improved odour control and a consistency around the effluent quality. To help us maintain the performance of the plant, we would like to remind Islanders to think carefully about what they put down the toilet or wash down the sink, as items such as fat, cotton buds and wipes can cause blockages in the sewer network as well as processing problems at the treatment works.”​

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