The Environment Agency commissioned AECOM to undertake the detailed design for the refurbishment of Hardmead and Stanstead radial gate structures.
Constructed in the 1970s, these structures had reached the end of their design lives. Recognising the opportunity to extend the life and improve the assets, the refurbishment aimed to replace the ageing single radial gates with pairs of tilting gates. This upgrade would not only enhance operational efficiency and reliability but would also enable integration of new fish and eel passes, aligning with regulatory standards under the Water Framework Directive (WFD). Crucially, this project sought to sustain the protection of over 200 properties situated along the river, ensuring both functionality and environmental responsibility.
Collaborative efforts
Close collaboration was paramount throughout this project. Our team engaged in numerous joint decisions, comprehensive reviews of options, and rigorous identification and mitigation of risks. We worked closely with our client, the Environment Agency, as well as with the contractor BAM Nuttall, the MEICA design team from Hunton Engineering, Arcadis as the ECC Project Manager, and Jacobs as the Principal Designer.
Overcoming hurdles
Throughout the commissioning process, the Environment Agency (EA) faced a multitude of challenges. Managing stakeholders in close proximity to the assets posed significant coordination hurdles. Obtaining the necessary permissions for works within the river, while ensuring appropriate contingency and emergency procedures, required thorough planning and negotiation. Furthermore, meeting the diverse requirements of end-users necessitated a comprehensive understanding of both technical specifications and community expectations.
Civil refurbishment design
AECOM's scope of work encompassed the civil and structural refurbishment design, including the intricate design of the fish pass and preliminary plans for the eel pass. The detailed design of the gates and eel pass were carried out by Hunton Engineering Ltd and Fishtek (for Hardmead only) respectively. Collaborating with specialist partners, our team ensured a holistic approach to the project's execution.
The services we provided extended beyond traditional engineering roles, encompassing preliminary environmental impact reporting, construction-focused environmental action plans, economic appraisals, and comprehensive construction design support. Leveraging digital tools such as Revit, hydraulic modelling software, and advanced structural analysis programs, we ensured precision and efficiency at every stage of the project. Our team also identified a solution to stabilise the ground beneath part of the existing structure, allowing the existing structure to accommodate the loads from the new structure without compromising its integrity.
Flood protection and environmental considerations
Key design challenges emerged during the planning phase, each demanding innovative solutions. Maintaining flood protection standards was paramount, as any compromise in this area could have severe consequences for the surrounding communities. Additionally, navigating the uncertainties associated with the existing structures required a blend of expertise and adaptability. Addressing the imperative for fish passage presented another hurdle, highlighting the project's broader environmental considerations. Furthermore, devising a design that could be constructed in multiple stages added complexity to an already intricate process. AECOM carried out hydraulic modelling to determine the optimal size and opening of the gates, ensuring no exacerbation of flood risk compared to the previous configuration.
Safeguarding communities and riverine species
Collaboration was key throughout the project's execution. Working closely with the client and contractor, we devised a construction strategy that minimised disruption while maximising efficiency. Constructing the new structure in stages allowed for progress while giving careful consideration to seasonal factors such as the winter shutdown period to mitigate potential flood risks.
In conclusion, AECOM's design played a pivotal role in the successful refurbishment of the Hardmead and Stanstead radial gate structures, along with the incorporation of fish and eel passes. This achievement highlights our expertise and commitment to technical excellence. By addressing complex challenges with innovative solutions and collaboration, AECOM enhanced operational efficiency and reliability, demonstrating a strong dedication to environmental sustainability and community well-being.