In January 2021, VolkerGround Engineering was awarded a contract by Deconstruct UK, to design and construct bearing piles and a secant wall, to assist them in the redevelopment of a former Chelsea Police station, within the London Borough of Kensington and Chelsea, into a seven-storey residential led mixed use development.
Our in-house design team worked closely with Deconstruct UK, to develop the most efficient and buildable solution for this scheme. Originally the secant wall was designed around a Continuous Flight Auger (CFA) solution, but because of the location of the proposed secant wall in relation to the adjacent property, we advised that a combination of CFA and Rotary techniques was the optimal solution to enable construction within 550mm of the existing structure. This design was adopted by the Client and VolkerGround Engineering commenced on site in June 2021, mobilising our Soilmec SR95 and SR75 dual purpose concrete piling rigs.
We constructed three sides of the secant wall using our Soilmec SR95 in CFA mode, installing 187 600mm diameter piles. We then installed the fourth side using our Soilmec SR75 in rotary mode to install the remaining 52 piles within 550mm of the adjacent building.
The basement structure required 80, 600mm diameter bearing piles to depths ranging between 21.3 metres and 31 metres. We constructed 77 in CFA mode and three in rotary mode due to the position and the depths required.
When carrying out the CFA piling, our team used a cage vibrator in conjunction with a handling crane, to ensure the steel reinforcement cages were placed to the correct level.
Logistics for this scheme were carefully planned to take into consideration the proximity of site hoardings and adjacent buildings to the working area and a nearby school. Kensington and Chelsea is a densely populated area, so we managed our delivery times within restricted hours so as to minimise risk and disruption to pedestrians and road users, whilst maintaining production in line with the programme.