Doka delivers ‘millimetre perfect’ formwork solution for hydropower generator plinth

Doka’s adaptable formwork system and design expertise proved essential to the challenging delivery of a complex concrete plinth at a major hydropower plant.

The installation was key to the £70m refurbishment of Lochay Hydro Power Station in Perthshire, Scotland. The concrete plinth’s construction will support a 27 MW hydro generator.

The 1.5m high plinth, which has a 1.5m inner radius and a 6m diameter, needed to be integrated within an existing structure inside the constrained, working power station. This left no margin for error. Hence, installing contractor, TRS Formwork, required a formwork solution that reduced or even eliminated the need for onsite redesign or rework.

Doka ingenuity, combined with its customisable Radius Top 50 formwork, met the brief perfectly.

Design challenges

Lochay Power Station delivers approximately 170GWh of renewable generation for the region each year. Its ongoing refurbishment, on behalf of developer SSE Renewables, includes replacing interior main generation components with modern, efficient technology. The upgrade will increase the station’s hydro power generation output.

Prior to its construction, the site’s new 12-sided, corbelled plinth provided a distinct design challenge. Its complex angles, along with its integration with older concrete, excluded the use of some formwork techniques. In a setting where generator alignment and load transfer were critical, bespoke shuttering was crucial. Such a system needed to incorporate myriad contours and integrate with new and existing concrete details to create a smooth finish. Doka’s timber-beam Radius Top 50 formwork was integral to this outcome. The system’s adaptability ensured each pre-assembled component complied with the plinth’s intricate shape. The formwork’s fast, easy assembly contributed to reduced cycle times and the project’s completion within the agreed 12-week timeframe.

Hybrid strategy for millimetre accuracy

In devising a workable formwork solution, Doka produced a 3D-led design of the plinth. Its engineers used this to calculate the formwork’s precise radii and angles, and create a shuttering form shaped from the design.

Teams also developed a bespoke connecting plate to establish a WS10 formwork ring, manufactured precisely to the required angle. This level of accuracy improved material efficiency and consequently helped reduce the project’s environmental impact.

Doka’s hybrid strategy involved its teams cutting and preparing forms off-site and supplying them partially constructed. This allowed for final adjustment in situ to align forms with the existing concrete.

Doka’s detailed 3D manufacturing and assembly drawings ensured the formwork’s precise on-site assembly. The bespoke connecting plate and WS10 ring system also enabled forming of the intended geometry without modification.

Tom Scott, Project Manager at TRS Formwork, said: “What Doka provided us in terms of design, formwork and technical support was first class. The final design worked perfectly, without us making any on‑site adjustments.

Tom continued: “The resulting 12-sided plinth, with its complex corbels and angles, worked to the millimetre. The precision allowed seamless integration between the new plinth and the existing structure while keeping the power station operational and the refurbishment programme on track.”

Conclusion

This project offers an inspirational example of how Doka formwork, combined with deep design expertise and 3D-driven engineering, provides a safe, time and cost-effective platform for highly complex pours in challenging environments. For the Lochay Power Station’s plinth’s construction, the contractor was able to integrate new and existing concrete efficiently and with total confidence.