Since 2015, the Caledonia Water Alliance (CWA) – a joint venture between AECOM and Morrison Water Services (MWS) – has led the delivery of Scottish Water’s capital investment infrastructure programmes.
Initially appointed to oversee water infrastructure under Scottish Water’s SR15 investment programme (2015–2021), CWA’s success earned it a 6-year contract extension for SR21 (2021-2027), with an expanded remit to include all wastewater infrastructure across Scotland.
As of November 2024, the alliance has delivered £722 million in water and wastewater infrastructure improvements on behalf of Scottish Water. This includes renewals, maintenance, refurbishments and new assets which, together, are creating a safer, more resilient water and wastewater network.
As a CWA partner, AECOM’s multidisciplinary team is providing expertise across civil, structural, process, geotechnical and MEICA engineering, as well as project feasibility, detailed design and strategic advisory services. We are also providing leadership, commercial and project management support across CWA projects, which includes customer and communications services.
An integrated, coordinated approach
Collaboration lies at the heart of CWA’s success. By co-locating 170 professionals from AECOM, MWS and Scottish Water and allowing early input from construction teams, we’ve created a truly integrated approach.
This has improved understanding of potential challenges before construction begins and has contributed to a strong safety record with fewer work-related injuries – as demonstrated by our low lost time frequency rate. It has also allowed us to bridge the gap between planning, design, delivery and handover, ensuring designs are practical and work well in real-world conditions.
A testament to this success, Scottish Water became the UK’s first water utility to achieve ISO 44001 certification – an international standard for collaborative business relationships – with AECOM’S support.
Enhancing urban water quality and incorporating nature-based solutions
As Scotland’s urban population continues to grow, the need for resilient wastewater infrastructure is more vital than ever.
In 2021, Scottish Water launched its Improving Urban Waters Routemap, which aims to enhance water quality in urban environments, increase biodiversity, cut pollution and ensure healthier, more sustainable water systems in communities across Scotland.
By reducing sewer spills, increasing monitoring in high-priority areas and working closely with stakeholders, CWA is helping safeguard Scotland’s water environment for future generations.
As nature-based solutions become increasingly critical to Scottish Water’s long-term plans, CWA is also implementing these approaches alongside traditional infrastructure including Sustainable Drainage Systems (SuDS) such as ponds and swales. These have the dual benefit of reducing flood risk while creating greener, healthier spaces for residents to enjoy.
Creating secure, resilient and sustainable water infrastructure
CWA has delivered several landmark projects across Scotland since 2015 that are helping meet the needs of a growing population, addressing climate impacts and contributing to broader net-zero and environmental, social and governance (ESG) goals.
Highlights include:
- The £90 million Glasgow Strategic Resilience Project, which is protecting water supplies for one million people across Greater Glasgow and Ayrshire. This involved building a 12-kilometre pipeline, a high-capacity pumping station and an advanced dosing system that transfers up to 50 million litres of water daily. By employing innovative construction materials and techniques such as low-concrete designs to lower carbon emissions, the project achieves significant sustainability benefits. Solar panels will also offset the power demands at the new Ibrox pumping station, with the new mains using gravity to reduce power use by 60 per cent.
- The Bertha Park Project – this comprises two major schemes in Perth: the £45 million Bertha Park Wastewater Project and the £31 million Bertha Park Water Project. The wastewater project expands Perth’s infrastructure with a focus on resilience and flood risk reduction. A notable feature is the 500-metre-long, 2.2-metre-diameter composite steel-reinforced sewer designed to manage increased water flow, improve River Tay’s water quality and minimise environmental impact. The water project supports Perth’s growth, delivering a flexible water supply to over 6,000 properties. It includes a new 6-megalitre Distribution Service Reservoir, expandable to meet future demands.
- The Marchmont Flood Alleviation Project – Scottish Water has invested £8.9 million to expand sewer capacity and stormwater storage to tackle recurrent flooding in Edinburgh’s Marchmont area. This project includes a 20-metre-wide, 16-metre-deep underground storm tank capable of holding approximately 3.5 million litres of stormwater. Scheduled for completion in 2025, the scheme will redirect stormwater into the tank during heavy rainfall – significantly reducing the risk of flooding to local properties.
Applying our digital expertise for better project outcomes
As part of our commitment to continuous improvement, AECOM’s digital team is leveraging technology to boost efficiency and transparency across CWA projects. For instance, early in the partnership, we introduced a 360-degree camera and app to facilitate remote site monitoring. This not only enhanced site safety by reducing unnecessary visits but also cut emissions as a result.
Recognising the advantages of remote engagement, we also developed virtual consultation rooms, allowing the public to engage with project information at their convenience. Given their success, Scottish Water has since adopted this model more widely.
Furthermore, our digital and GIS teams collaborated with Scottish Water’s digital teams to streamline data processes with tools such as Autodesk Construction Cloud, Civil 3D/Revit and ArcGIS Online. This has resulted in numerous benefits – from improved data accuracy to greater transparency of the design and delivery process. Thanks to our innovative use of geospatial technology, this work earned an ESRI award for significantly advancing project quality and operational efficiency.
Saving costs and reducing construction time
CWA’s expertise is helping Scottish Water achieve its SR21 targets, which include reducing costs by 30 per cent and getting to site in half the time. For example, in a £25 million pipe rehabilitation programme in Ayrshire, we implemented sliplining – a trenchless technique for repairing pipelines – that saved approximately £3.5 million and avoided 22 kilometres of urban excavation.
CWA also helped save over £2 million on the Irvine Bypass Trunk Main project. Through our redesign, the pipeline length was shortened by 2 kilometres. This not only cut costs, but also significantly reduced construction time and community impact.
By adopting a “right first time” approach and reducing the need for rework, CWA is ensuring projects are completed on schedule and within budget, while keeping disruptions to a minimum.
A future-focused approach to water and wastewater management
CWA’s ongoing success has received widespread recognition over the years. Most recently, the alliance was shortlisted for the ‘Team of the Year’ award at the 2024 Utility Week awards and nominated for the Asset Management Initiative of the Year Award at the 2024 Water Industry Awards.
These achievements reflect the strength of collaboration across teams, combining expertise from multiple disciplines to help Scottish Water meet its strategic goals while maintaining regulatory compliance.
As a trusted partner for more than 25 years, AECOM will continue to support Scottish Water in creating future-ready water and wastewater systems to meet future demands—facilitating Scotland’s urban growth, enhancing climate resilience and advancing net-zero goals.
All photos courtesy of Paul Milligan and the Caledonia Water Alliance