Prepared by: Independent Hazard Analysis Jupiter Drill Break Tierra del Mar Subsea Cable Landing Site Tillamook County, Oregon Peer-Reviewed by: 28 August 2020 The business of sustainability 28 August 2020 Independent Hazard Analysis Jupiter Drill Break Tierra del Mar Subsea Cable Landing Site Tillamook County, Oregon Paul Krause, PhD Kim Marcus LG, LEG, LHG ERM Partner ERM Partner Nikki Payne, P.E. ERM Partner ERM-West, Inc. 1050 SW 6th Ave. Suite 1650 Portland, Oregon 97204 Geosyntec Consultants, Inc, (Peer-Reviewer) 920 SW 6th Ave, Suite 600 Portland, Oregon 97204 © Copyright 2020 by ERM Worldwide Group Ltd and / or its affiliates (“ERM”). All rights reserved. No part of this work may be reproduced or transmitted in any form, or by any means, without the prior written permission of ERM www.erm.com Version: 1.0 28 August 2020 INDEPENDENT HAZARD ANALYSIS CONTENTS Jupiter Drill Break CONTENTS EXECUTIVE SUMMARY .............................................................................................................................. 1 1. INTRODUCTION ................................................................................................................................ 2 1.2 Overview of Analysis ............................................................................................................................ 4 1.3 Credentials of Preparers ....................................................................................................................... 4 2. BACKGROUND .................................................................................................................................. 6 2.1 Description of Typical Drilling Operation ............................................................................................... 6 2.2 Summary of Incident and Remaining Materials at Drilling Site ............................................................. 7 2.2.1 Incident Description ............................................................................................................. 7 2.2.2 Incident Response ............................................................................................................... 8 2.2.3 Drilling Mud Composition ..................................................................................................... 9 2.2.4 Other Remaining Materials .................................................................................................. 9 2.3 Surrounding Environment and Geology ................................................................................................ 9 2.3.1 Geology ............................................................................................................................... 9 2.3.2 Natural Resources ............................................................................................................. 10 2.3.3 Water Quality ..................................................................................................................... 10 3. IMPACT ANALYSIS OF REMAINING MATERIALS ....................................................................... 11 3.1 Water Quality and Natural Resources ................................................................................................ 11 3.1.1 Toxicity Potential ................................................................................................................ 11 3.1.2 Migration of Material .......................................................................................................... 14 3.2 Geologic Events .................................................................................................................................. 15 4. IMPACT ANALYSIS OF ATTEMPTED RECOVERY ...................................................................... 18 4.1 Recovery Options ............................................................................................................................... 18 4.1.1 No Action Alternative ......................................................................................................... 18 4.1.2 Horizontal Drill Recovery ................................................................................................... 18 4.1.3 Dredge Recovery ............................................................................................................... 19 4.2 Recovery Impacts ............................................................................................................................... 19 4.2.1 Drilling Option .................................................................................................................... 19 4.2.2 Dredge Option.................................................................................................................... 20 5. CONCLUSION .................................................................................................................................. 21 6. LITERATURE CITED ....................................................................................................................... 22 APPENDIX A GEOSYNTEC PEER REVIEW ACKNOWLEDGEMENT APPENDIX B SITE VISIT PHOTO LOG APPENDIX C MUD REPORT 28 APRIL 2020 APPENDIX D SAFETY DATA SHEETS APPENDIX E POTENTIAL ECOTOXICITY EVALUATION APPENDIX F GEOLOGIC FIGURES List of Figures Figure 1 Site Location 3 Figure 2 Depth of Remaining Materials 8 www.erm.com Version: 1.0 28 August 2020 Page ii INDEPENDENT HAZARD ANALYSIS CONTENTS Jupiter Drill Break Acronyms and Abbreviations CFR Code of Federal Regulations cm centimeter DOGAMI Department of Geology and Mineral Industry EC effective concentration Edge Edge Cable Holdings USA, LLC ERM ERM-West, Inc. FOC fiber optic cable gal gallon Geosyntec Geosyntec Consultants, Inc. HDD horizontal directional drilling lb pound LC lethal concentration OCS Oregon Conservation Strategy OPRD Oregon Parks and Recreation Department OSHA Occupational Safety and Health Administration SDS safety data sheet TCI tri-cone www.erm.com Version: 1.0 28 August 2020 Page ii INDEPENDENT HAZARD ANALYSIS EXECUTIVE SUMMARY Jupiter Drill Break EXECUTIVE SUMMARY The analysis herein was prepared in response to a drill break that occurred on 28 April 2020, during the drilling operation for the Jupiter subsea cable system in Tierra del Mar, Tillamook County, Oregon. The horizontal directional drilling (HDD) drilling pipe broke, resulting in drill tooling (mostly 6-inch steel) and drilling mud (collectively “Remaining Materials”) being left at a depth of 50 to 70 feet below the seafloor, between approximately 1,690 and 520 feet offshore. In response to the occurrence and follow-up requests from agencies, ERM-West, Inc. (ERM), a global environmental consulting firm, conducted an independent analysis of potential impacts associated with the drill break and leaving the drill tooling and drilling mud (collectively “Remaining Materials”) in place, with the following objectives: 1. Identify environmental, economic, recreational, and scenic impacts for consideration by the public, stakeholders, and regulatory agencies. 2. Evaluate the potential options for recovery of the Remaining Materials and environmental, economic, recreational, and scenic impacts of each. ERM’s analysis concludes that there are currently no adverse environmental, scenic, recreational, or economic impacts resulting from the drill break or presence of Remaining Materials 50 to 70 feet below the sea floor, nor is there a reasonably conceived scenario (e.g., earthquake, tsunami, long-term coastal erosion) that would expose the Remaining Materials to the surrounding environment and result in future impacts. For this reason, the recommended environmentally-preferred alternative is to leave the Remaining Materials in place. The following summarizes the conclusions of this analysis: The drilling mud has presumably hardened and is effectively encasing the drilling materials trapping additive constituents and limiting movement or migration within the surrounding sediment and rock. The buried drilling components are solid metal pieces that will corrode in place over time at a very slow rate given the low levels of oxygen and seawater at such depths; this oxidation process will create a hardened shell around the metal, which is surrounded by mud; migration would be negligible. The lithology (e.g., sediment) surrounding the Remaining Materials provides an additional layer of migration prevention with a minimum 50 foot buffer between the Remaining Materials and the biologically-active benthic zone or seafloor. This depth of burial essentially eliminates any ecological or public risks associated with leaving the Remaining Materials entombed in the seafloor strata. There are no mapped seismically active faults intersecting the Remaining Material that would pose a risk for severing or displacing the drilling equipment. Based on the gradual slope of the seafloor, the predicted locations for submarine mass-movements would be at least 6 to 10 miles west of the Remaining Materials. Based on Federal Emergency Management Agency (FEMA) tsunami observations, scour depths near the Landing Site are estimated to be fewer than approximately 10 feet; therefore, they do not impose a risk to uncovering the Remaining Materials in the event of a tsunami. Regarding recovery options, using HDD to recover the Remaining Material is a nonviable option given the extremely low probability of success, as the drill bit would need to perfectly align with the 6-inch bore pipe 520 feet from shore. The second option