Environmental Statement European Offshore Wind Deployment July 2011 Centre European Offshore Wind Deployment Centre Environmental Statement Appendix 7.1: UXO Threat and Risk Assessment Unexploded Ordnance (UXO) Threat & Risk Assessment with Risk Mitigation Strategy Project: Aberdeen Offshore Wind Farm Client: Vattenfall Report Number: P2219 TRA September 2010 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. The contents of this document shall not in whole or in part: (i) be used for any other purpose, (ii) be disclosed to any member of the recipient’s organisation not having a need to know such information, nor to any third party individual, organisation or government, (iii) be stored in any retrieval system nor be reproduced or transmitted in any form by photocopying or any optical, electronic, mechanical or other means, without the prior written permission of the Managing Director, 6 Alpha Associates Limited, Quatro House, Frimley Road, Camberley, GU16 7ER, UK. Draft Version 1.0 Prepared by: Gary Hubbard 29th September 2010 Reviewed by: Lee Gooderham 29th September 2010 Released by: Simon Cooke 29th September 2010 P2219TRA ii Aberdeen Offshore Wind Farm Contents Contents ..................................................................................................iii! Appendices ............................................................................................. vi! Acronyms and Abbreviations ..................................................................vii! Executive Summary................................................................................ ix! 1! Introduction......................................................................................... 1! 1.1! Overview........................................................................................................................1! 1.2! Background...................................................................................................................1! 2! Report Methodology ........................................................................... 2! 2.1! Structure........................................................................................................................2! 2.2! Sources of Information ................................................................................................3! 2.3! Standards, Guidance and Best Practice.....................................................................3! 2.4! Joint Service Explosive Ordnance Disposal Operations Centre, UK ......................3! 3! Proposed Intrusive Works................................................................... 5! 3.1! Marine Site Investigation .............................................................................................5! 3.2! Marine Cable Installation .............................................................................................5! 3.3! Turbine Installation.......................................................................................................5! 3.3.1! Foundations ...............................................................................................................5! 3.3.2! Scour Protection Systems........................................................................................6! 4! Sources of UXO Contamination.......................................................... 7! 4.1! General ..........................................................................................................................7! 4.2! British Military Activities and Firing Ranges .............................................................7! 4.2.1! Civilian and Military Firing Ranges..........................................................................7! 4.2.2! Black Dog Firing Range ............................................................................................7! 4.2.3! Munition / Explosives Disposal................................................................................8! 4.3! Allied Sea Minefields....................................................................................................9! P2219TRA iii Aberdeen Offshore Wind Farm 6.4.3 Mine Clearance ...........................................................................................................9! 4.4! Aerial Bombing Campaign.........................................................................................10! 4.4.1! Overview...................................................................................................................10! 4.4.2! Shipping Lanes, Sea Convoy Routes and Ports...................................................10! 4.4.3! Tip and Run..............................................................................................................10! 4.4.4! Defensive Anti Aircraft Artillery (AAA) ..................................................................10! 4.5! Shipwrecks / Downed Aircraft...................................................................................11! 5! Explosive Threat Items ..................................................................... 12! 5.1! General ........................................................................................................................12! 5.2! Weapon Fill Materials.................................................................................................12! 5.2.1! High Explosives (HE)...............................................................................................12! 5.2.2! Low Explosives........................................................................................................12! 5.2.3! Propellants ...............................................................................................................13! 5.3! Artillery Projectiles.....................................................................................................13! 5.4! Torpedoes ...................................................................................................................14! 5.5! Sea Mines ....................................................................................................................14! 5.5.1! General .....................................................................................................................14! 5.5.2! Fuzing .......................................................................................................................15! 5.6! Depth Charges ............................................................................................................15! 5.7! German Air-Delivered Weapons................................................................................16! 5.7.1! Iron Bombs...............................................................................................................16! 6! UXO Ground Penetration, Burial and Migration................................ 18! 6.1! General ........................................................................................................................18! 6.2! Seabed Migration........................................................................................................18! 6.3! Seabed Burial..............................................................................................................18! 6.4! Seabed Penetration ....................................................................................................19! 7! UXO Detonations.............................................................................. 20! 7.1! Initiation Scenarios.....................................................................................................20! P2219TRA iv Aberdeen Offshore Wind Farm 7.2! Detonation Variables..................................................................................................20! 7.3! Underwater High Explosive Detonations .................................................................21! 7.3.1! Underwater Detonation Hazards ............................................................................21! 7.3.2! Direct Effects of Ordnance Detonation..................................................................21! 7.3.3! Effect of Explosive Shockwave and Gas Bubble on Supporting Vessels..........21! 8! UXO Risk Assessment Factors ........................................................ 23! 8.1! Source – Pathway – Receptor ...................................................................................23! 8.1.1! Source.......................................................................................................................23! 8.1.2! Pathway ....................................................................................................................23! 8.1.3! Receptors .................................................................................................................23! 9! Semi-Quantitative Risk Assessment................................................. 24! 9.1! Overview......................................................................................................................24! 9.2! Risk Rating..................................................................................................................24! 9.3! Risk Rating Criteria ....................................................................................................25! 9.4! Definition of Consequence and Probability .............................................................25!