For construction sites affected by WWII unexploded ordnance, Fugro Engineering Services provide land and marine bomb surveys and clearance ahead of piling, drilling and excavations using the latest detection technology and experienced professional staff. We offer complete advice on how to economically mitigate against UXO risk using Fugro's extensive experience in geophysics, drilling and Magnetometer Cone Penetration Testing (Magcone).
Piling, excavations and drilling have a significant safety risk from unexploded bombs on some sites in the major cities and near Luftwaffe bombing targets. World War II and subsequent military activities have created a legacy of unexploded ordnance (UXO) that still pose a risk to construction activities sixty years on.
Our primary UXO services are surface Geophysics and Magcone probing. These are mainly used before excavation or piling to ensure aerial-delivered unexploded bombs are not encountered. Our Magcone is a totally new and much improved magnetometer housed in an ultra-low diameter cone fabricated from exceptionally high quality non-magnetic metals. The result is the highest standards of safety at a lower cost.
Simultaneously, our Magcone incorporates geotechnical cone penetrometer measurements (including friction ratio & pore water pressures) allowing soil engineering information to be obtained at each UXO probe location. The information can result in cost savings being realised for the foundation phase of the development.
To get a quote for a Magcone probing survey or other UXB service then please send an email to the address below containing a brief description of the site, the piling layout and a geotechnical report, borehole log or CPT results. If a UXO desk study or risk assessment is available please also forward it or request a price (from £200 per site).
Contact: Steve Poulter tel +44 (0)1491 820423 email: firstname.lastname@example.org
For marine surveys Fugro EMU Ltd offer towed marine magnetometer UXO surveys and further information is available at http://www.fugroemu.com/downloads-/ and as shown by the schematic video : http://www.youtube.com/watch?feature=player_detailpage&v=NqpyPHT1VUs
Unexploded bombs or UXB of London and other UK cities
The four most common size of German aerial-delivered (or air-dropped) high explosive bombs are, in ascending order of frequency: 1000kg, 500kg, 250kg and 50kg.
A 1000kg bomb was discovered at a construction site in Stratford, London in 2008 during piling works at the canal adjacent to Three Mill island. The bomb was in a dangerous condition and could not be moved. It took 5 days to dispose of it by a controlled explosion on site and during this time it caused disruption to traffic, residents and public due to the high risk.
A 500kg bomb was discovered at Bower's Marsh in Essex in 2010 during a geophysical survey on land owned by RSPB. It had penetrated several metres deep into the ground and was disposed of by a controlled explosion on site on the same day as discovery, by the Royal Logistics Corps.
A 250kg bomb was discovered at Mile End in east London during construction of a housing estate in 2006, and also near the former Queen Elizabeth hospital in Erith, east London.
A 50kg UXB was discovered during excavation of a basement for a new residential block at the western end of the Excel complex in east London. City airport was closed for several days until the bomb was disarmed. Nearby hotels were evacuated. The bomb was a few metres deep and was exposed by an excavator bucket. Piling on the site was subsequently cleared of UXB risk by Fugro's Magcone probing method in case other bombs existed on site. A number of other bombs had been identified in previous years during construction of the Excel conference centre.
There are many other examples of German UXB's and other types of UXO being discovered on construction sites in UK particularly in east London but also in Sunderland, Plymouth, Reading, Paddington, Dartford and along the coast. Bombs are also frequently encountered in other european countries. In recent years there have been a number of deaths in Germany and Austria due to construction work such as piling.
About 80% of the high explosives bombs dropped on Britain in WWII were the thin-cased general purpose bomb (SC series 50kg to 2,000kg) also known as Sprengbombe-Cylindrisch or Minenbomben. The remainder were armour-piercing or semi-armour-piercing known as Panzerbombe and Sprengbombe-Dickwandig). The thin-cased SC bombs usually had a thick nose welded to a thin-walled tubular body and sheet steel or alloy tail fin. The bodyweight of the SC50 consisted of 55% explosives.
Uniquely, German bombs were mainly armed by an electric fuze whilst other countries used mechanical and chemical fuzes. The aircraft carried a battery that was connected to the bombs and as they were released the fuzes would be charged. When the bomb struck its target, the impact caused the trembler to function and electrically ignite the flash pellet, which fired the initiator (gaine), which fired the sensitive booster charge which in turn fired the main filling of the bomb.