Bodac in the baltic sea - underwater EOD

Bodac has recently been active in the Baltic Sea with the Dutch offshore service provider N-Sea, having been engaged on the Nord Stream 2 project, preparing for the installation of pipelines in the Finnish sector of the Baltic Sea. This forms part of the Nord Stream 2 planned route for the subsea pipelines which will cross the territorial waters and exclusive economic zones of Russia, Finland, Sweden, Denmark and Germany.

N-Sea is an integrated subsea service provider in survey and IMR (Inspection, Maintenance, Repair). They have routinely delivered cost effective solutions for subsea infrastructures and assets in support of the international oil, gas and renewable sectors with their survey, identification and UXO removal capabilities. BODAC helps augment the delivery of these services and together in this project, N-Sea and BODAC have conducted pre-detonation survey, target investigation and identification, using magnetometer array, and hi-resolution sonars, specially equipped Remote Operated Vehicles (ROV) and removed positively identified UXO objects through an Explosive Ordnance Disposal (EOD) process that utilises the Cobra Mine Disposal System (MDS).

Method
BODAC and N-Sea develop an EOD solution and technical approach to clear and dispose of the historic UXO that was encountered by incorporating the Cobra MDS, ensuring that UXO was disposed of in a safe and controlled manner and minimised the impact upon the environment with particular focus on monitoring and preserving marine life in the vicinity. Environmental mitigation included the use of a marine mammal observer, passive acoustic monitoring of fish- and cetaceans, acoustic deterrence devices (for seals) and a big bubble curtain. Bubble curtain equipment is deployed and operated by the support vessel and is designed to be laid around the UXO target. Compressors carried onboard are activated, feeding compressed air into the bubble curtain hose, creating a wall of bubbles which significantly dampens the acoustic shock during destruction activities. 

The target positions were investigated by the Work Class ROV which was specially equipped with a number of sensors, spot lasers for accurate measurement and high definition, wide angle colour cameras for planned operations between 40m to 80m depth of water. In total, over seventy potential targets were investigated, which were either removed, neutralised or destroyed by the EOD Engineers, having positively confirmed that the targets were UXO, in line with the sequence of events set out in the pre-prepared disposal plans, each of which was approved by the Client. Destruction of the targets was achieved using a controlled means of initiation, carried out whilst ensuring that adjacent shipping had been warned of the nature of the explosive operations and they remained at a safe distance throughout. 

The Cobra MDS was prepared on the deck of the MV Geosund and once the explosive charges had been put together for UXO disposal operations. The Cobra apparatus would be attached to the ROV so that when launched, the ROV could carry the donor charge to the target, using the Cobra placement unit to achieve the best angle of projection, so that the UXO can be either neutralised and/or disposed of. After placing the explosive charge with the unit, a float is released to the surface which has an antenna attached for a controlled and secure RF initiation that would be conducted from the MV Geosund at a safe distance from the explosive hazard, having already recovered the ROV out of the water. Thereafter, the area would be re-surveyed to confirm the success of the operation and remove any items of debris.

Conclusion
The key to achieving project success was to ensure that underwater geophysical survey data before and after underwater disposal operations was accurate, so that targets of interest could be correctly identified and UXO hazards removed along planned pipeline routes. Project integration between N-Sea, BODAC and the other implementing partners was also an essential requirement. The teams had prepared a risk-based methodology and applied best-practice in terms of ensuring relevant levels of qualification and competence.