Congleton Wastewater Treatment Works (WwTW) - AMP7 Upgrades
Congleton Wastewater Treatment Works (WwTW), located in Cheshire, has long served the town of Congleton and its surrounding communities by treating domestic and commercial wastewater. Historically, the site relied on traditional infrastructure such as trickling filters and humus tanks. However, with increasing environmental regulations and a growing population, the existing system began to show its limitations. It struggled to effectively remove nutrients like phosphorus and ammonia and lacked the resilience to manage stormwater during heavy rainfall. These challenges made it clear that a comprehensive upgrade was essential to ensure continued compliance, operational efficiency, and environmental protection.
Purpose
The AMP7 upgrade at Congleton WwTW was driven by the need to modernise the facility in line with evolving environmental standards and to prepare for future population growth through 2035. The project aimed to significantly reduce phosphorus and ammonia levels in the treated effluent, expand the site’s treatment capacity, and enhance stormwater and flow monitoring systems. These improvements were designed not only to meet current regulatory requirements but also to ensure the long-term sustainability of the site, contributing to cleaner water for the community and better protection for the River Dane and its surrounding ecosystems.
What we did
To deliver a future-ready treatment facility, the project team implemented a series of major upgrades. These included the construction of a new Activated Sludge Plant (ASP), two Final Settlement Tanks (FSTs), and a Blue Water Bio tertiary filtration system. The FSTs were built using precast concrete sections that were lifted into place by cranes, while the rest of the infrastructure was constructed using formed reinforced concrete (FRC) to ensure durability and chemical resistance. Mechanical and electrical installations played a central role in the plant’s performance, incorporating aeration systems, pumps, mixers, and chemical dosing equipment to support enhanced nutrient removal. Significant electrical upgrades were also completed, including the installation of new Motor Control Centre (MCC) kiosks and integration with SCADA systems for advanced monitoring and control. The Blue Water Bio system now provides high-efficiency tertiary treatment, and the new stormwater management and flow monitoring systems ensure compliance with regulatory standards. All systems underwent thorough dry and wet commissioning to validate performance, ensuring the site is well-equipped to meet both current and future demands.
Although the reuse of existing infrastructure was minimal, the new installation was constructed offline and later integrated into the existing system. Approximately half of the original trickling filters and humus tanks were decommissioned following the successful implementation of the new ASP. This approach allowed for a seamless transition to the upgraded system without disrupting ongoing operations.
The project also embraced innovative technologies and construction methods. The modern ASP and FST systems, though based on century-old principles, have evolved into highly efficient, compact, and environmentally friendly solutions. By building the new setup separately from the existing plant and connecting it only once fully operational, the team ensured minimal disruption. This strategic approach enabled the retirement of outdated infrastructure and marked a significant advancement in wastewater treatment at the site.
Working within the constraints of a live treatment plant posed several challenges. The site had limited space and a complex network of underground services, both documented and undocumented, due to multiple historical upgrades. Despite these constraints, the team maintained uninterrupted daily operations, including the continuous movement of tankers for chemical deliveries and sludge removal. This was achieved through effective interface management and open, transparent communication with the client, which helped maintain strong working relationships throughout the project.
One of the most complex tasks involved a major over pumping operation to safely divert incoming flows and allow improvements to the live inlet channel. This enabled the successful installation of a new MON4-compliant flume, which accurately measures flow without interrupting the treatment process. The operation required meticulous planning and coordination across multiple contractors and trades, and its smooth execution marked a key milestone in modernising the site.
Coordination with third parties was also critical to the project’s success. Upgrading the site’s power supply required close collaboration with the power network owner, and thanks to careful planning, the work was completed smoothly and on schedule. At the same time, United Utilities (UU) needed to maintain operations on a site that was already busy with tanker traffic and space constraints. To support this, the project team worked closely with UU’s teams, providing daily traffic management plans that detailed crane positions, access restrictions, and alternative routes. These plans were shared with UU’s project managers and logistics teams to ensure safe and efficient site operations.
Although the Congleton WwTW upgrade was located in a remote industrial area with limited direct community impact, the project team remained committed to delivering effective stakeholder engagement. Engagement with nearby residents ensured they were informed about the works and the long-term environmental benefits, such as improved water quality and protection of the River Dane. The team maintained open communication and responded to feedback, reinforcing trust and transparency.
Project successes
The project has delivered significant improvements in the quality of treated water, successfully reducing phosphorus and ammonia levels to meet stringent environmental standards. The site’s capacity has been expanded to support population growth through 2035, and the upgraded monitoring systems for stormwater and treatment flows ensure continued compliance and operational resilience. These enhancements will have a lasting positive impact on the local environment, contributing to cleaner rivers and healthier ecosystems.
What truly sets this project apart is not just the technical achievements, but the spirit of the team behind it. Despite numerous challenges, some within and others beyond their control, the team demonstrated remarkable resilience and unity. There were moments when meeting critical regulatory milestones seemed uncertain, but through open communication, mutual support, and a shared commitment to excellence, the team rallied together and delivered a successful outcome. This camaraderie and determination are what make the Congleton WwTW upgrade a standout success in the AMP7 programme.