UACE2017 Proceedings: Sonar and UXO

• Session:
  Acoustics of marine renewable energy developments
• Paper:
  Sonar and UXO
• Author(s):
  Peter Dobbins
• Abstract:
  Offshore wind, wave and tidal stream renewable energy developments generally occur in shallow water. If close to shipping lanes these areas may have been mined in past conflicts, but if away from shipping lanes they may have been used to dump obsolete and unwanted Unexploded Ordnance (UXO). In either case, a potential threat to shipping remains and appropriate mitigation is needed. The first step is to survey the area in question and identify likely hazards, and the only practical tool for such surveys is sonar. However, there are difficulties. Over the intervening period, these objects are likely to have become encrusted with marine growth, making them indistinguishable from naturally occurring features such as rocks, or they may have been buried by sediment, impenetrable to conventional minehunting and sidescan sonars. This paper will review a number of projects aimed at solving this problem ranging from the joint Anglo-French Buried Mine Sonar programme dating back to the 1980s, through the pan-European SITAR project (Sea floor Imaging of Toxicity and Assessment of Risks caused by buried waste) to the commercial SEApara AUV mounted compact sub-bottom profiler. It will be explained that, even more important than the hardware, including the use of parametric arrays, appropriate acoustic waveforms must be chosen that give both seabed penetration and adequate resolution to classify the objects that may be detected as potential hazards or not. Finally, the paper will review the acoustics associated with such problems and discuss potential solutions, looking particularly at new approaches that may speed up surveys and enhance their reliability.
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Contact details

• Contact person:
  Dr Peter Dobbins
• e-mail:
  
• Affiliation:
  Consultant
• Country:
  United Kingdom