6 Alpha Associates Limited Quatro House, Frimley Road Camberley, Surrey GU16 7ER Tel: +44(0) 203 371 3900 Web: www.6alpha.com Unexploded Ordnance (UXO) Threat & Risk Assessment with Risk Mitigation Strategy for Cable Installation Project: NorthConnect Client: MMT Report Number: P5530 Disclaimer This document is of UK origin and is copyright © 6 Alpha Associates Ltd. It contains proprietary information, which is disclosed for the purposes of assessment and evaluation only. 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Client Final Version 2.0 Document Written by Review Issued Version 0.1 RG 18/01/2017 RR 25/01/2017 LA 25/01/2017 Version 0.2 RG 03/02/2017 RR 06/02/2017 LA 10/02/2017 Version 1.0 RG 22/03/2017 RR 28/03/2017 LA 31/03/2017 Version 2.0 RG 08/05/2017 RR 08/05/2017 RG 08/05/2017 P5530 NorthConnect ii Contents Contents ................................................................................................ iii Appendices ........................................................................................... vii Annexes ............................................................................................... viii Tables .................................................................................................... ix Acronyms and Abbreviations .................................................................. x Executive Summary .............................................................................. xiii 1 Introduction ..................................................................................... 1 1.1 Overview .................................................................................................................... 1 1.2 UXO Threats in the North Sea. ................................................................................. 1 1.2.1 Munitions Migration ............................................................................................ 2 1.3 Marine Risk Management Framework ...................................................................... 2 1.4 Purpose ...................................................................................................................... 3 1.5 Client Intention .......................................................................................................... 3 2 Report Methodology and Best Practice ........................................... 4 2.1 Methodology .............................................................................................................. 4 2.2 Constaints and Limitations ...................................................................................... 4 2.3 Scope ......................................................................................................................... 4 2.4 Sources of Information ............................................................................................. 5 3 On-Site Operations ......................................................................... 6 3.1 Proposed Operations ................................................................................................ 6 3.2 Pre-Lay Operations ................................................................................................... 6 3.2.1 Offshore Geophysical UXO Survey .................................................................... 6 3.3 Marine Cable Installation .......................................................................................... 6 3.4 Cable Landfall ............................................................................................................ 7 P5530 NorthConnect iii 4 Sources of UXO Contamination ...................................................... 8 4.1 Generally .................................................................................................................... 8 4.2 Aerial Bombing .......................................................................................................... 9 4.2.1 Generally .............................................................................................................. 9 4.2.2 LOT A – UK Nearshore ...................................................................................... 10 4.2.3 LOT B – North Sea ............................................................................................. 10 4.2.4 LOT C – Norway Fjord ....................................................................................... 11 4.3 Sea Minefields (Axis and Allied) ............................................................................. 11 4.3.1 Generally ............................................................................................................ 11 4.3.2 Mine Clearance by Vessels ............................................................................... 11 4.3.3 Mine Clearance Analysis ................................................................................... 12 4.3.4 First World War (WWI) Minefields ..................................................................... 12 4.3.5 WWII Minefields ................................................................................................. 13 4.3.6 LOT A – UK Nearshore ...................................................................................... 13 4.3.7 LOT B – North Sea ............................................................................................. 14 4.3.8 LOT C – Norway Fjord ....................................................................................... 14 4.4 Training Areas ......................................................................................................... 15 4.4.1 Historical Training Areas .................................................................................. 15 4.4.2 LOT A – UK Nearshore ...................................................................................... 16 4.4.3 LOT B – North Sea ............................................................................................. 16 4.4.4 LOT C – Norway Fjord ....................................................................................... 16 4.4.5 Modern Training Areas ...................................................................................... 16 4.4.6 LOT A – UK Nearshore ...................................................................................... 17 4.4.7 LOT B – North Sea ............................................................................................. 17 4.4.8 LOT C – Norway Fjord ....................................................................................... 17 4.5 Coastal Defensive Features .................................................................................... 17 4.5.1 LOT A – UK Nearshore ...................................................................................... 17 4.5.2 LOT B – North Sea ............................................................................................. 18 P5530 NorthConnect iv 4.5.3 LOT C – Norway Fjord ....................................................................................... 18 4.6 Naval Battles ............................................................................................................ 18 4.7 Shipwrecks .............................................................................................................. 19 4.8 Munitions Dumping ................................................................................................. 20 4.8.1 Generally ............................................................................................................ 20 4.8.2 LOT A – UK Nearshore ...................................................................................... 21 4.8.3 LOT B – North Sea ............................................................................................. 21 4.8.4 LOT C – Norway Fjord ....................................................................................... 21 5 UXO - Seabed Conditions, UXO Migration, and Detonation .......... 23 5.1 Generally .................................................................................................................. 23 5.2 Local Sea Bed Conditions .....................................................................................