Barhale has completed a programme of upgrades at St Helens Wastewater Treatment Works on the Isle of Wight on behalf of Southern Water, delivering improvements designed to increase treatment capacity and strengthen long-term operational resilience.

The project centred on the construction of a new 9m diameter humus settlement tank and associated infrastructure, increasing Full Flow to Treatment capacity to 17.2 l/s. The scheme also included the installation of new flow monitoring equipment to meet UMON4 requirements, alongside upgrades to the site’s Motor Control Centre and control systems.

Construction activities progressed across civil, mechanical and electrical disciplines during the project, with works involving complex process connections to existing infrastructure. Activities included modifications to chambers, flow redirection within the live humus system and the installation of additional process equipment such as auto desludge units, actuators and new sampling systems, including a V-notch chamber.

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Electrical works involved the installation and termination of systems across several assets, as well as modifications to existing Programmable Logic Controller (PLC) and Human Machine Interface (HMI) systems. The works were carried out under controlled operational procedures to maintain the continued operation of the treatment site.

Supporting civil engineering works included the construction of a retaining wall, resurfacing of site roads, installation of footpaths and bollards, and the addition of permanent security fencing intended to improve access and site safety.

The project has also entered an extensive testing and commissioning phase involving telemetry integration, reliability assessments and water sampling to confirm compliance with regulatory standards. Staged shutdowns and system integrations were coordinated to enable new equipment to be connected without affecting ongoing operations.

Barhale and Southern Water also undertook community engagement activities throughout the programme. Traffic management permits and consents were implemented to reduce impacts on local roads, while a public drop-in session at a nearby community centre provided residents with an opportunity to learn more about the scheme and speak directly with project representatives.

During the project, the delivery team also carried out a beach litter-picking initiative aimed at supporting the local environment and community.

The programme was completed on a live operational site, requiring close coordination between Barhale and Southern Water throughout delivery. Environmental and safety measures formed a key part of the project, including steps taken to protect a veteran oak tree during construction works.