Careful excavation was required, negotiating gas pipes, tanks, and other structures. Safety hoarding was installed along with various other cordons protecting staff in the car parks from our works. The work site was limited on space requiring ingenuity with techniques used, particularly in avoiding the propane gas tanks. A live-dig methodology was used with careful ecological supervision to excavate a trench, exposing tunnels passing under the tanks and car park. These entrances were gated and monitored, and the surrounding area meshed to prevent re-digging. Once the exclusion period had elapsed, a grouting method was used to fill the tunnels. This served the purpose of both underpinning the gas tanks and car park, whilst infilling the empty tunnels and chambers. An ecological watching brief was present when required. Once the grouting had cured off the site was returned to use, with meshing applied to all exposed ground surfaces and the site made good.