Adelaide Exchange provides for 18,000m² of office space and a boutique hotel over a two level 181 space basement carpark with long frontages to both Adelaide Street and Alfred Street and gable junctions with old historic buildings. The site posed many issues to be addressed before the basement’s structural form could be finalised. Historically the site comprised pond-lands, filled with spoil from the nearby gasworks site. This posed contamination issues. In more recent times the 80m by 50m site found itself in the middle of the fully developed, congested conservation area to the rear of Belfast City Hall. Desk studies indicated the flanking buildings originality to be Victorian warehouses constructed on timber piles. Site investigation confirmed the presence of fill material overlaying “Belfast Sleach” with a perched watertable at surface and an artesian aquifer at depth. In advance of the commencement of construction, full condition surveys were undertaken of the flanking properties and a presentation was made to satisfy the developer’s funders that due diligence could be demonstrated in the conception of the basement’s structural form. That having been successfully completed along with a demolition pre-contract and archaeological study, construction of the basement in 750mm diameter propped contiguous piles with high quality architectural-grade finished Caltite waterproof floor and lining walls proceeded.