The redevelopment of this 19th-century coal depot – once the marshalling yards of the industrial revolution – into shops and restaurants is a case study in why the client has turned repeatedly to David Packham to perform construction management magic.
Realising the central yard below the buildings would be extremely busy during the construction period, he added a major benefit to the scheme and derisked the end date by installing most of the yard’s drainage and attenuation as part of an enabling package.
He challenged the structural scheme as vastly overengineered, expensive and impractical. Working with in-house engineers, he agreed a reduced scope, deploying and monitoring 171 movement sensors as the substructure and superstructure elements were installed. His solution avoided placing loads or deflection on the heritage structure (the longer of the parallel depot pair is grade II-listed) just as effectively as the original methodology.
The technical difficulties were enormous. With the roof pitch changing in three directions as it sweeps around the central node, the 44 slate courses of the roof for the new upper storey had to be maintained despite the rafter length gaining three metres as the roof proceeds. Not to mention complex geometrical steelwork, on two buildings 33m apart, was needed so the pair of parallel roofs could curve out to touch each other at a kissing point. David managed it all impeccably by repeated access design iterations.
Or consider the requirement for over 350 piles, 27m deep and 1,000mm in diameter, supporting 1m-deep pile caps constructed against heritage walls with foundations just 500mm down. David’s solution involved changing the pile design from pairs to slightly smaller trios achievable by the smallest mini-rig. With 1km of mostly temporary underpinning, he then executed a piling sequence that resembled a production line more than a piling programme.
He used BIM modelling to link structural analysis and 3D scans of existing buildings to check service co-ordination and accuracy. It allowed for precise site-ready fabrication where on-site alterations would have been costly and time consuming. On a scheme where programme was the key driver (because potential tenants wanted a decent lead-in to open for Christmas and would have otherwise delayed moving in until Easter), it was a crucial win.
Most schemes go through value engineering, but its success on this project stemmed from David’s commitment to engaging all parties. So, for example, when the architect wanted to remove an existing structure over the main sewer and replace it with a stair and Thames Water wanted a design allowing future access, the solution driven by him was a precast cantilevering stair over the sewer with lifting points, adapted balustrade and broken risers permitting removal with minimal disruption.