Pelham Street

Franki were approached to tender for the piling works to a site in Pelham Street consisting of a contiguous piled wall basement box. A retained façade formed the site boundary on one side and existing properties on the opposite side with a long narrow run of site in which to construct the piled wall, meaning use of standard sized rig was not possible.

Where there was concern for state of the retained façade and to reduce risk of overflighting during pile construction (augering to depth) in close proximity to the retained structure, the preferred option was to proceed with a CFA technique in lieu of SFA or cased mini rotary piles as this enabled enhanced productivity and allowed pile construction to be monitored with on-board rig instrumentation without introducing additional risks.

Following design review and working with the given site restrictions such as the retained façade and a number of existing piles and associated groundbeams which encroached in to the wall line, a scheme was devised which maintained the proposed diameter of 350mm piles to provide maximum possible footprint space inside the basement and span across where existing foundations clashed with the wall line.

With a number of sections of wall spanning over existing foundations, we installed a total of 117no 350mm diameter CFA piles to 8m on the restricted site with our GEAX EK40 rig which was able to work safely within the site confines and complete the works more efficiently than smaller SFA or cased mini rotary rigs.

With the benefit of our in-house design team, we were also able to quickly address and overcome issues on the pile wall layout and wall line where existing foundations were found to be extending further along the wall than allowed for  meaning delays in the regard were mitigated.