Pell Frischmann Successfully Delivers Multi-Disciplinary Survey of Vyrnwy Aqueduct

Pell Frischmann’s survey team has successfully delivered a comprehensive multi-disciplinary survey of the historic Vyrnwy Aqueduct (pronounced vuhn·wee) in Wales, supporting the Canal & River Trust with their vital General Assessment and Scour Assessment works. The Canal & River Trust, a charity responsible for safeguarding over 2,000 miles of historic waterways across England and Wales, required the survey to continue maintenance of this aqueduct. Pell Frischmann has enhanced these assessments with pioneering technology that enables precise mapping above and below the water line.

The survey team delivered a large-scale topographic, bathymetric, terrestrial, and UAS survey of the aqueduct and its surrounding environment. The key services included:

• High-precision control installation

• Topographic surveying

• Terrestrial laser scanning (LiDAR)

• UAS surveying (LiDAR & photogrammetry)

• Single-beam echosounder

The location of the aqueduct has challenging conditions – including dense vegetation and proximity to the River Vyrnwy. To overcome this challenge, our surveyors employed the DJI M350 RTK with the Zenmuse L2 LiDAR platform. Using these tools enabled our survey team to penetrate the canopy, capture precise topographic detail, and rapidly collect large volumes of data and enhance efficiency while reducing on-site risks.

In addition, the team established a robust control network, ensuring survey accuracy and enabling reliable repeat monitoring. To validate and enhance the deliverables, we deployed our in-house Leica RTC360 terrestrial laser scanner to produce millimetre-accurate 3D geometry of key structures. This was especially critical where the Canal & River Trust requested re-surveying to monitor potential movement or subsidence.

For additional visual detail, our in-house DJI M3E drone captured high-resolution imagery, generating photogrammetric models to complement the LiDAR datasets.

Recognising the importance of the riverbed in the scour assessment, the team also undertook a bathymetric survey using the Seafloor TriDrone unmanned which is fitted with a single beam echosounder. This allowed safe, efficient collection of 3D measurements from the riverbank, producing accurate bathymetric data where no existing records were available.

Aaron McKevitt, Associate at Pell Frischmann said:

“It has been great assisting the Canal & River Trust with this project. Our scope was complex but allowed us to deliver accurate and precise data enabling the Vyrnwy Aqueduct to continue to be open for all.”

By integrating multiple survey methodologies – spanning terrestrial, aerial, and hydrographic techniques – we successfully produced high-resolution, multi-dimensional datasets that have delivered a complete visual of the Vyrnwy Aqueduct and its environment. These outputs will support the Canal & River Trust in safeguarding one of Wales’ important historic structures for generations to come.