The project, which took the site’s capacity from 3.2 litres per second (L/s) up to a possible 10.6 L/s, has now completed a successful reliability period and has been handed over to the client, Scottish Water.

Screening incoming wastewater flows is a critical part to the treatment process, as it removes the large solid items that would cause damage and blockages to downstream equipment. In order to maintain sufficient screening, equipment must be fit for purpose and well maintained.

The age of the plant and its location within a small village supported by summer seasonal tourism created challenges for WGM Engineering, which delivered a full design plus the civils, construction, mechanical, electrical, instrumentation, control and automation (MEICA) fit-out and commissioning of the upgraded plant for Scottish Water. Following completion of site work in July, the site went through extensive testing before achieving final sign off.

WGM Engineering project manager, Scott Ross, said: “The screening upgrade work at Tyndrum has been a very rewarding but challenging project to be involved with. This was due to the environment and time constraints that the project was delivered in.

“Throughout the work, the plant had to remain functional to continue serving the village, so temporary screenings and over-ground pumping were installed for the duration. Installation of these temporary screenings and the new upgraded screening faced unforeseen hurdles due to the age of the existing infrastructure on-site.

“Tyndrum WwTW was first built in 1981 and has gone through some smaller upgrades in the past. As a result, a number of uncharted services were discovered at critical locations of the planned construction works. This presented many challenges and saw our design be redrafted multiple times during the project.

“Compliance regulations meant we couldn’t simply remove these existing services or go around, under or over them. Any newly laid electrics or water pipes need to maintain specific distances from other buried services and from the surface, presenting a challenge for the design team.”

The village of Tyndrum sits at the foot of the Scottish Highlands and is located on the West Highland Way.

It is a popular tourist destination during the summer months and its local economy is dependent on the seasonal visitors, Scott explained. “It was critical for Scottish Water that the project be completed and in full operation before the summer tourist season began in July, which gave us just over seven months to deliver and commission the upgrades. This left a tight window for the work, especially when unforeseen redesigns were required.”

To navigate the unknown services, WGM’s site team used ground excavation techniques that do not break ground in traditional ways, avoiding the risk of hitting unknown cables or pipes.

Scott Ross added: “Due to the concerns of causing any damage or injury, we worked closely with our suppliers to mitigate the risks caused when excavating around services. Vacuum excavators were used, which greatly reduced the need for any mechanical digging, and it aligned with Scottish Water’s ‘zero strike’ policy for services.”

Taking the retrofit install approach was a favoured solution for the project because it enabled carbon and resource savings, Scott explained. “Our design team was tasked with and delivered a solution that increased the lifespan of existing assets, removing the need to demolish the current site and build a new treatment plant.

WGM worked with surrounding landowners in the area and was able to reuse some of the construction materials to provide hardstanding areas, additional parking for local businesses and improved boundary fencing. We estimate a carbon saving of 10–11 tonnes of CO₂ equivalent.

“The mechanical, electrical, instrumentation, control and automation (MEICA) installation also required modifications to the existing electrical control panel. The panel was the original one and therefore didn’t have the capacity for the newly installed infrastructure. This also required an upgrade to fully integrate the new screens.”

Scottish Water project manager, Robin Johnson, commented: “At Tyndrum WwTW, our collaboration with WGM Engineering delivered an efficient, low-carbon retrofit that kept the works online while more than doubling screening capacity.

“By working together to navigate legacy services and a tight seasonal window, we strengthened resilience, improved compliance with environmental consents and minimised disruption for customers, the local community and stakeholders. This upgrade future-proofs a critical stage of the treatment process and supports Scottish Water’s commitment to sustainability and value for money.”