Modular Upgrade of Eela Water Treatment Works Driving Industry Innovation

RSE is delivering a major upgrade to Eela Water Treatment Works (WTW) for Scottish Water, an essential plant that supplies up to 4.3 million litres of drinking water daily to around 5,400 residents and the Sullum Voe Oil Terminal. Built in 1978, the existing plant has long faced challenges associated with coming to the end of its serviceable life – issues now being addressed through RSE’s innovative and modular engineering approach.

Transforming Water Treatment Through Modular Innovation

Appointed as Principal Contractor and Principal Designer, RSE is leading the full delivery of civil, MEICA, process engineering and commissioning of the works to replace the existing plant with a new 5.7Ml/d ceramic membrane treatment facility. The new works will deploy PWNT’s C37 CeraMac® ceramic membrane system, which RSE has developed into a state-of-the-art modular solution that enhances water quality and operational resilience.

To minimise disruption and accelerate delivery, RSE has applied its innovative Design for Modular Assembly (DfMA) strategy, constructing 42 modular Transportable Treatment Units (TTUs) at its advanced manufacturing facility in Muir of Ord, before transporting them to Shetland. Each modular unit has made the 24-hour sea journey via the Port of Cromarty Firth to the Sullum Voe Oil Terminal before final road delivery and offload to site. RSE’s delivery team worked in partnership with the client and our logistics partners, Malin Group, heavy lift specialists and experts in the transportation and handling of out of gauge cargo, to oversee meticulous logistical planning and seamless coordination. This collaboration was fundamental to ensuring the efficient and safe delivery of the 42 modules, with a total lead time of 7 months from factory to site.

“This project represents one of the most remote and logistically complex modular water treatment deployments in the UK, delivered at an unprecedented pace. Our modular approach allows for parallel construction, reduces programme risk, and significantly cuts carbon.”

said Duncan Gillies, Senior Project Manager, RSE Water Technologies

Technology and Sustainability at the Core

RSE’s modular suite including the m-CTU®, m-BWU®, m-CIP®, m-NAC®, and m-NAL® standard products, delivers consistency, scalability, and reduced environmental impact. These repeatable, plug-and-play designs reduces design time, critical spares, and on-site disruption while improving safety and quality assurance to allow savings in the programme costs and carbon, ensuring significant benefits over bespoke site builds.

Through innovative design, RSE has achieved a 34% reduction in embodied carbon across its modular ceramic treatment product range. This has been made possible by transitioning from welded to bolted structures and using green carbon and stainless steel. Factory-based commissioning also allows early detection of defects, minimising rework and ensuring higher quality control before deployment. Health and safety outcomes have also improved, thanks to the project teams’ growing familiarity with the product and the continuous refinement of designs to eliminate potential hazards.

Advanced Digital Engineering

The RSE BIM team has used the Autodesk Construction Cloud Federated Model to produce detailed 4D animations of the construction and installation sequence. This visual planning tool supports transparent collaboration between project teams, stakeholders, and clients, ensuring every phase of delivery is fully coordinated and efficient.

Key Benefits of BIM (Building Information Modelling):

• Improved Collaboration & Coordination: Centralised digital BIM models allow all project stakeholders to work together seamlessly, reducing miscommunication, design conflicts, and project delays.
• Enhanced Visualisation & Decision Making: Detailed 3D models provide clear insights into complex infrastructure, helping stakeholders make informed decisions throughout the project life cycle.
• Cost and Time Savings: Digital clash detection, coordinated models, and early problem-solving minimise errors before construction begins. This reduces costly rework, prevents delays, and supports more efficient use of materials and resources.
• Proactive Risk Management: Simulations, clash detection, and early site visualisation minimise construction errors, safety hazards, and operational disruptions.
• Data-Driven & Future-Ready Delivery: BIM generates structured, accurate, and reliable data that extends beyond project completion. This future-ready approach enhances asset information management, ensures compliance with ISO 19650, and enables smarter, evidence-based decision-making throughout the entire asset lifecycle.

Delivering Programme Schedule Excellence

The Eela WTW upgrade remains on schedule, with the first modular units having successfully arrived on-site in August 2025, with commissioning scheduled to begin in January 2026 and water in to supply due in November 2026.

“Our mission is to redefine how water treatment infrastructure is delivered. Through modular design, digital integration, and sustainable materials, RSE is setting new standards for quality, safety, and environmental responsibility.”

said Michael Agolini, Delivery Manager, RSE Water Technologies.

Key Milestones:

• Construction Contract Award – January 2025
• Off-site Fabrication & Assembly – February 2025
• First Modular Unit Delivery – August 2025
• Commissioning Start – January 2026
• Water in Supply – November 2026