NINIAN NORTHERN PLATFORM LATE LIFE & DECOMMISSIONING PROJECT Report – Environmental Statement P0005-BMT-EN-REP-00006 February 2017 Ninian Northern Platform Late Life and Report - Environmental Decommissioning Project Statement Document prepared by BMT Cordah Limited on behalf of CNR International (UK) Limited Document Number: P0005-BMT-EN-REP-00006 Date: February 2017 Revision: B2 Page: 2 Ninian Northern Platform Late Life and Report - Environmental Decommissioning Project Statement Table of Contents ABBREVIATIONS AND ACRONYMS ........................................................................................................ 10 GLOSSARY.............................................................................................................................................. 16 NON-TECHNICAL SUMMARY ................................................................................................................. 19 Regulatory Context ............................................................................................................................... 19 Scope of the NNP Decommissioning Programme ................................................................................. 22 Decommissioning Studies ..................................................................................................................... 22 Recommended Decommissioning Options ........................................................................................... 22 Environmental Setting and Sensitivities ............................................................................................... 23 Key Environmental Concerns ................................................................................................................ 25 Energy Use and Atmospheric Emissions ............................................................................................... 25 Underwater Noise ................................................................................................................................. 25 Seabed Disturbance .............................................................................................................................. 26 Socioeconomic Impacts ........................................................................................................................ 26 Waste….… .............................................................................................................................................. 26 Accidental Events .................................................................................................................................. 27 Environmental Management ................................................................................................................ 27 Conclusions ........................................................................................................................................... 27 1. INTRODUCTION ..................................................................................................................... 28 1.1. Location of the Ninian Northern Platform ............................................................................ 28 1.2. Project Background and Purpose .......................................................................................... 28 1.3. Purpose of the Environmental Impact Assessment .............................................................. 30 1.4. Regulatory Context ................................................................................................................ 30 1.5. Report Structure .................................................................................................................... 32 1.6. Methodology ......................................................................................................................... 33 1.6.1. EIA Scoping Workshop ........................................................................................................... 33 1.6.2. Environmental Impact Assessment Process .......................................................................... 33 1.6.3. Scoping .................................................................................................................................. 35 1.6.4. Transboundary and Cumulative Impacts ............................................................................... 36 1.7. Comparative Assessment ...................................................................................................... 36 1.8. Supporting Studies ................................................................................................................ 37 2. PROJECT OVERVIEW .............................................................................................................. 38 Document Number: P0005-BMT-EN-REP-00006 Date: February 2017 Revision: B2 Page: 3 Ninian Northern Platform Late Life and Report - Environmental Decommissioning Project Statement 2.1 NNP Facilities and Materials to be Decommissioned ............................................................ 38 2.1.1 Topsides ................................................................................................................................. 39 2.1.2 Jacket.. ................................................................................................................................... 40 2.1.3 Platform Wells and Conductors ............................................................................................. 41 2.1.4 Drill Cuttings Pile ................................................................................................................... 41 2.2 Assessment of Alternative Use of the NNP ........................................................................... 43 2.3 Decommissioning Options ..................................................................................................... 44 2.4 Overview of the CA Process................................................................................................... 44 2.5 Preparatory Work .................................................................................................................. 47 2.5.1 Post CoP Preparation for NNP Decommissioning ................................................................. 47 2.5.2 Well P&A ................................................................................................................................ 47 2.5.3 Engineering Down, Cleaning and Topsides Preparation ....................................................... 48 2.5.4 Idle Phase .............................................................................................................................. 49 2.6 Options for Decommissioning the NNP ................................................................................. 49 2.6.1 Topsides Decommissioning Options ...................................................................................... 49 2.6.2 Jacket Decommissioning Options .......................................................................................... 51 2.6.3 Decommissioning Options Considered for the Cuttings Pile ................................................. 54 2.6.4 Onshore Dismantling and Disposal ........................................................................................ 54 2.6.5 Long-term Monitoring Requirements for Materials Left in the Sea ...................................... 56 2.7 Cumulative Impacts of Wider Field Decommissioning ......................................................... 57 2.8 Recommended Decommissioning Options for the NNP and Drill Cuttings Pile .................... 57 3. ENVIRONMENTAL BASELINE .................................................................................................. 58 3.1. Location of the NNP............................................................................................................... 58 3.2. Environmental Surveys .......................................................................................................... 58 3.2.1. Ninian Pre-Decommissioning Environmental Survey ............................................................ 58 3.2.2. Acoustic and ROV Survey ....................................................................................................... 59 3.3. Physical and Chemical Environment...................................................................................... 61 3.3.1. Bathymetry ............................................................................................................................ 61 3.3.2. Currents ................................................................................................................................. 61 3.3.3. Meteorology .......................................................................................................................... 61 3.3.4 Sea Temperature and Salinity ............................................................................................... 63 3.3.5. Seabed Sediments ................................................................................................................. 63 3.4. Biological Environment .......................................................................................................... 75 Document Number: P0005-BMT-EN-REP-00006 Date: February 2017 Revision: B2 Page: 4 Ninian Northern Platform Late Life and Report - Environmental Decommissioning Project Statement 3.4.1. Plankton ................................................................................................................................