FP McCann Precast Concrete Segmental Shaft and Cover Slab Installed At Eden Project
Status: Completed
Location: Eden Project Cornwall
Division: Segmental Shafts and Precast Concrete Cover Slab
Civil Engineering Contractor: Matt Durbin Associates
Market Sector: Tunnels and Shafts
FP McCann has supplied a 5.5 metres ID precast concrete segmental shaft and associated cover slab that has been installed as part of major drainage repair works at Cornwall’s Eden Project.
Extensive storms at the site in December 2020 resulted in three landslides to the side of the clay quarry caused by the build-up of major volumes of floodwater below ground.
A tunnel running beneath the Eden Project designed to take all excess surface water away from the site became blocked, partly due to the poor condition of the tunnel in combination with the excess mud and debris.
Somerset based tunnelling and shaft sinking specialist Matt Durbin Associates has undertaken the flood alleviation and drainage tunnel rehabilitation works on behalf of the Eden Project client.
In order to access the flooded tunnel located approximately 13.5 metres deep below ground, the 5.5m ID shaft was excavated to accommodate the first FP McCann segmental ring and concrete jacking collar to enable the precast concrete shaft to then be sunk using the caisson method of build. The 15 ring deep shaft was then constructed, three of which were front bolted together with 12 back bolted segments, providing edge protection over the open excavation.
Once complete, pumping equipment was lowered down the shaft to enable the tunnel to be cleared of flood water prior to the remediation of the drainage tunnel itself by Matt Durbin’s confined space working team.
To complete the work, a FP McCann 5.5m precast cover slab was installed on top of the shaft.
Commenting on the shaft construction, Keiron Lonergan Matt Durbin’s site-based Chartered Civil Engineer says, “The use of such universal precast concrete segmental shafts allows for an extremely efficient and structurally sound caisson build process. Construction is simple and allows for ease of ground excavation. The smaller site footprint taken compared to other shaft construction options, helps to reduce the volume of material to be removed thereby minimising the environmental impact and important factor for the Eden Project team. From the installation of the first rings, the shaft build continued uninterrupted”.
The natural overflow from the drainage tunnel forms a cascade down the quarry face. As a new addition to the site, the Eden Project’s landscape team are taking advantage of the major repair works to design a magnificent secondary overflow waterfall set against the backdrop of the Rainforest Biome. This will help to alleviate pressure on the drainage tunnel in any future storm events.
For sales and technical enquiries, contact Cadeby on 01455 290780 or email sales@fpmccann.co.uk
