Case Study

When redevelopment plans were drawn up for the Royal Arsenal site at Woolwich in South East London, checking for unexploded ordnance was the number one priority for contractors Fitzpatrick Contractors Ltd. Previously the site of an ordnance factory, the Arsenal was also heavily bombed in World War II –records indicate that about 20% of them failed to explode.

With a contract to build a light use industrial estate, Fitzpatrick were acutely aware of the potential risks posed by unexploded ordnance. At an early stage of the project BACTEC International Ltd., a specialist Explosive Ordnance Disposal (EOD) and landmine clearance company, were called in to develop a Risk Mitigation Strategy. The initial detailed site reconnaissance was followed by further research and assessment which took into account a number of factors, including the existing site conditions, the history of the site, the construction methodology for the new estate and the project’s timetable constraints.

BACTEC’s Strategy included Explosive Ordnance Safety and Awareness briefings for all site personnel and the presence of an explosive ordnance disposal engineer to provide on-site support during the initial site clearance. BACTEC’s new intrusive survey technique was also used to clear over 850 separate pile locations to a maximum bomb penetration depth of 12 metres. The initial phase of the groundworks identified the presence of explosive ordnance at three different locations. BACTEC uncovered and removed over forty three-inch projectiles, which proved to be inert. Two live four-inch projectiles were subsequently discovered, with BACTEC co-ordinating their disposal with the appropriate authorities. One further six-inch solid projectile shot was also uncovered and removed. The groundworks revealed previously unrecorded extensive foundations, which enabled BACTEC to give clearance to pile in the area without the need for an intrusive survey and significantly reduce both time and costs in the process.

The second phase consisted of an intrusive survey conducted in advance of the piling operation to ensure that the positions selected for piling were clear from buried magnetic objects that could have been explosive ordnance. During this phase four targets were identified that required further investigation. The target investigation was completed within 48 hours of the targets being originally identified. As none of the targets were ordnance related clearance to pile was given to Fitzpatrick Contractors, keeping the piling programme on schedule.