WGM recently delivered a complex scope of works at Prestonpans Wastewater Treatment Works for Scottish Water, involving the installation of four duckbill check valves within a Category 1 confined space influenced by tidal conditions.
Failure of the existing valves had allowed hydrogen sulphide (H₂S) to re-enter the building, restricting access to parts of the site and contributing to the deterioration of structural steelwork. Replacement works were therefore essential to restore safe and reliable operation.
Due to the specialist nature of the equipment, replacement valves were sourced from Canada with a 17-week lead time. During this period, our team undertook detailed planning to develop a safe and effective delivery strategy, enabling the works to be carried out within a live operational environment.
Project Overview
An initial installation attempt was stopped due to an inability to safely manage water levels, reinforcing our safety-first approach. Additional control measures were subsequently introduced, including the use of diesel pumps and a Vetter bag, allowing safe water level management and enabling works to progress.
Health and safety remained central throughout delivery, with measures including drone surveys to minimise confined space entry, robust planning and methodology, and continuous monitoring of tidal and weather conditions. Environmental protection was also a key priority, with all waste responsibly returned to the main inlet for treatment.
The project required close coordination with Scottish Water and key supply chain partners. Enviroclean provided a Category 1 rescue team and recycler to support chamber washdown and level control, while Hiab Hire Scotland delivered a complex lifting operation.
To date, two of the four valves have been successfully installed, with the remaining works planned in line with upcoming low tide windows, in close collaboration with Scottish Water.
This project demonstrates WGM’s ability to safely deliver complex, high-risk works through careful planning, strong collaboration, and engineering excellence.
