The location of constructing a vortex channel, which is a tube with 60m length and has been positioned vertically in the tunnel shaft, is the KEMPF site in Tower Hamlets is one of several Tideway sites, that is going to help carrying sewage from the overflow tunnel beneath the river to a sewage plant.
In order to advance the new 25km Tideway super sewer project’s series of complex construction works all over London, each site requires a unique temporary works solution, while the KEMPF shaft was completed in May 2021.
The advantage of cooperation with Mabey Hire was installing temporary works that would provide support to the vortex tube and hold it in position while the slip form rig cast the shaft’s secondary lining.
Tideway also wanted an alternative to the more time-consuming solution used on previous sites of casting a large concrete plinth to provide the required support.
The temporary propping scheme was to be installed first, with the vortex tube then lowered down between the props and secured before the secondary shaft lining was cast. As such, precision was essential, with the positioning of the vortex tube needing to be perfect.
The process of designing, supplying, and installing the temporary propping scheme, which featured Mass 50 and Mat 125 props and Hymat HM100 jacks was up to Mabey Hire.
Following installing the propping tower and placing the vortex tube, the Hymat jacks were used to make any final adjustments to the positioning of the tube.
The main challenge for the project was site access since only a tight and limited working space was available.
The contractor had to consider how they would transport the propping equipment down to the bottom of the 60m shaft. Another consideration was how to work within the small base of the shaft to assemble and install the temporary propping scheme.
Having limited access to this site, Mabey Hire had to carefully sequence works because once they had constructed one part of the system, they would have been unable to access other sections.
According to Mabey Hire national account manager Grahame Duffy: “This is where our in-house installation capabilities really came into play, with our install team working closely with our field engineers to ensure the installation process went as smoothly as possible.”