Ordnance Detection
As part of the investigations for new port developments at Harwich and Felixstowe, the Land and Marine Survey Group has completed two phases of survey works:
- Conventional marine geophysical surveys comprising bathymetry, side scan sonar and seismic reflection works to investigate the variation of seabed sediments.
- Marine and land based ordnance detection surveys.
The ordnance detection surveys were specified by the Client after a dredger working on an earlier phase harbour development inadvertently recovered a bomb which detonated onboard the vessel. This caused significant vessel damage although there no one was injured. A search of WWII historical records indicated that there was a significant risk of other Unexploded Ordnance (UXO) being present on the site.
The Survey Group deployed two different types of detectors:
- Magnetometers to detect ferrous components of bombs. About 50% of the weight of most German WWII bombs are made of ferrous metal.
- Electromagnetic devices which detect non-ferrous metals such as brass used in shell cases and aluminium which was used for incendiary devices.
Over 300 line kilometres of UXO clearance work were carried out along lines 5 metres apart both on land and overwater (some of which was extremely shallow). This work was to be conducted prior to the following stage of the investigation which involves drilling and cone penetration testing on land and overwater. |
