Our first complex London ground investigation, Drapers’ Gardens was a great project for us in our first year of trading, and it was a pleasure to be working with Tony Taylor at Foggo Associates. Hugh St John at GCG was also involved and we worked alongside Museum of London Archaeology and GBG on parts of the investigation – an excellent team to be involved with.

All of the work was inside the existing building, which was supported on a thick raft. Parts of the raft were over 3 m thick, and formed of 1960s reinforced concrete over what appeared to be a weaker older unreinforced concrete, and we probably spent more time trying to reach soil than we did anything else on site. Once we had got through the basement slabs we drilled four boreholes with a low headroom cable percussion rig, to depths of between 38 m and 42 m. We also drilled a series of window sampler boreholes across the routes of two arms of the “lost” Walbrook river, mainly for archaeological investigation, but also to profile the old river channels.

The various elements of the field work – including a structural investigation commissioned from GBG – continued through much of 2003 and our final report was issued at the start of 2004. It certainly helped keep our small but growing team busy through the year.

by Steve Branch