SPI Piling were initially engaged for the main works, which involved a mixture of temporary and permanent piles to permit the construction of a new outfall structure into the bank of the river ouse.
The first installation was a 3 sided cofferdam driven into the existing bank of the river, which allowed Balfour Beatty to excavate and form the main working platforms, for the follow on piles. These allowed Balfour Beatty to excavate away the existing flood defence embankment, whilst maintaining the levels of defence required utilising the sheet piles. These piles were installed using an ABI telescopic Leader Rig.

Permanent piled wing walls were installed whilst Balfour Beatty excavated the main platforms. As access was restricted, not only by Balfour Beatty’s ongoing operations but by the river Banks themselves, these piles were installed using the Kowan WP150 TOSA Stillworker, minimising plant access requirements at the actual pile location. The same method was also used for the scour wall adjacent the river line itself. Some of these piles were subject to tidal working conditions and therefore careful planning of the operation was required to maintain productivity during times of high water.

Once Balfour Beattys excavation operation was complete the final permanent piles were installed, allowing the removal of the temporary works.

Due to the relationships generated on this work, SPI have now been invited to look at other items of work on the same scheme. The next tranche of work involved the design, supply and installation of a dam wall across the existing draining ditch. Again, access to the areas was restricted, and as such SPI Piling engineered a solution to simplify the installation and future extraction work of these piles. A sheet piled cofferdam was installed over part of the ditch, with tie rods to brace the upstand of the piles and allow access to complete a single sheet piled wall to the remainder, providing a cut off of the existing ditch.

Works are currently continuing on this scheme, and this case study will be updated in the coming months.