Dealing with Ordnance

摘要

The presence of ordnance (as opposed to the many other types of debris) in the seas, rivers, lakes and estuaries world-wide is not surprising given the number of wars that have taken place and that, in many areas. waste explosive materials have simply been dumped in what were once considered to be "quiet waters". Even where records exist of these materials in a limited number of specific areas when disposed of by Government Agencies, there can be no guarantee that disposal did not take place outside the specific areas or that the ordnance has not been subsequently moved by wave and current action. Ordnance can be found on the surface where the bed is hard or, in the case of sand or softer deposits, buried within them. While in the former they are relatively easy to find and removed prior to dredging, in the latter case it is much more difficult and they have to be dealt with safely both during dredging, on-board the dredger and. if material is dumped ashore, in reclamation. Individual pieces of ordnance, even when large, can be difficult to locate. For example, during the dredging of the submerged tube runnel trench for the Oresund Link project and despite a significant number of surveys (including diving surveys) during the investigation and design stages, ordnance was only found after dredging had commenced. Ordnance took the form of World War Two material, including large bombs and a detailed magnetometer survey was required. This survey was successful and there was no delay to the project. On the Medway Estuary (UK) where sands and softer sediments were present, some 770 pieces of ordnance were found during one dredging and reclamation project. The Contract specification assisted the contractor to limit his risks and bomb disposal experts were required on the vessels at all times. Attempts were also made to remove ordnance prior to dredging in an attempt to stop major pieces of ordnance entering the dredgers and. subsequently, the reclamation areas. If ordnance is expected the Authorities, Employer, Engineer and Contractor should be properly prepared.