Throughout July and August 2023, VolkerGround Engineering (VGE) completed works on quite an unusual site in Manchester, for Bowmer and Kirkland.
The location, close to Piccadilly Station, had been moth-balled at the start of the Covid-19 pandemic, with only the foundation works having been completed. After nearly three years the project was resurrected, but the design of the building had changed to an extent that validation of the previously constructed foundations was required.
The initial enquiry received was for VGE to design and install reaction piles, to facilitate static load testing to 1.5 x SWL of the constructed piles. This was a challenging task due to the already congested site; being close to a new basement wall and an existing Network Rail viaduct. The placement of anchors required close collaboration with the engineer and contractor to ensure there were no clashes. The size of the equipment, which was needed to test to almost 6MN, was an important consideration for the team.
With the site being on a split-level, the engineer requested four static tests, each test requiring four anchor piles. The programme to install anchor piles, de-rig and move level then install further piles was discussed and agreed, ensuring that our client understood the work scope to be undertaken in each area.
The works developed further from purely anchor piles, to VGE designing and constructing 11 piles to support the two tower cranes as well as 12 piles for the lower and upper levels respectively. This meant that the anchor pile installation became increasingly efficient, as there were more piles to be installed.
Finally, another five piles were added to the scope, with these piles being required to support an independent staircase. The total number of piles to be installed by VGE increased to 44, with four static tests up to almost 6MN.
Works commenced during extremely wet conditions, firstly in the new basement area where the contractor and their groundworker maintained the platform with continuous trimming and pumping-out of water from the surface. Working from two platform levels VGE installed the anchor piles, tower crane piles and bearing piles, before demobilising the piling rig ahead of programme.
The team then undertook the load testing on all four tests in a single visit, with the results being passed over to the client’s engineer for assessment.
The success of the scheme can be attributed to the close working relationship between all parties; VolkerGround Engineering, the main contractor, their ground works contractor, engineer and the temporary works engineer.