Attachment JRP IR 4.1 AMEC Environment & Infrastructure A division of AMEC Americas Limited 3456 Opie Crescent, Prince George, BC Canada V2N 2P9 Tel +1 (250) 564-3243 Fax +1 (250) 562-7045 www.amec.com LANDSLIDE-GENERATED WAVE HAZARD ANALYSIS KITIMAT ARM ENBRIDGE NORTHERN GATEWAY PROJECT Submitted to: Northern Gateway Pipelines Inc., Calgary, Alberta Submitted by: AMEC Environment & Infrastructure A division of AMEC Americas Limited Prince George, BC EG0926008 20 September 2011 Attachment JRP IR 4.1 Northern Gateway Pipelines Inc. Kitimat Arm Landslide-Generated Wave Hazard Analysis 20 September, 2011 IMPORTANT NOTICE This report was prepared exclusively for Northern Gateway Pipelines Inc., a subsidiary of Enbridge Pipelines Inc. (Enbridge) by AMEC Environment & Infrastructure1 Limited, a wholly owned subsidiary of AMEC. The quality of information, conclusions and estimates contained herein is consistent with the level of effort involved in AMEC services and based on: i) information available at the time of preparation, ii) data supplied by outside sources, and iii) the assumptions conditions and qualifications set forth in this report. This report is intended to be used by Northern Gateway Pipelines Inc., Enbridge only, subject to the terms and conditions of the contract between AMEC and Enbridge. Any other use of, or reliance on, this report by any third party, is at that party’s sole risk. 1 As of September 2011, AMEC Earth & Environmental changed its name to AMEC Environment & Infrastructure Attachment JRP IR 4.1 Northern Gateway Pipelines Inc. Kitimat Arm Landslide-Generated Wave Hazard Analysis 20 September, 2011 EXECUTIVE SUMMARY This report presents the results of a landslide-generated wave hazard assessment in support of a regulatory application for the Northern Gateway Project. The work was carried out by AMEC Environment & Infrastructure (AMEC) on behalf of Northern Gateway Pipelines Inc. The Northern Gateway Project (the Project) includes a planned crude oil and condensate terminal to be constructed on the west side of Kitimat Arm, about 6 km south of the Rio Tinto Alcan aluminum facility at Kitimat, BC. The study involved an examination of the phenomenon and nature of the hazard related to landslide-generated waves and is presented as a qualitative analysis, consistent with the evaluation of other geohazards associated with the proposed project. The study area included the marine area from the north end of Kitimat Arm south to beyond Coste Island. The analysis has been supported by desktop studies, literature reviews and numerical modelling as well as a limited fieldwork program that included geophysical surveying in Kitimat Arm. Recently completed multibeam echo sounding (MBES) surveys conducted in 2009 and 2010 by the Canadian Hydrographic Service (CHS) provided relatively high resolution bathymetry throughout the study area. The Kitimat Arm area had two reported landslide-generated waves in 1974 and 1975. A significant aspect of the study was an evaluation of these past events, including triggering mechanisms, in support of the evaluation of the future hazards to the Project. In addition to the experiences in Kitimat Arm, additional cases from other areas with similar hazards, such as Norway, Alaska and other locations in British Columbia were reviewed This review has shown that very large landslides moving rapidly in the marine environment are required to generate waves that are significant beyond typical marine surface conditions. The results of the review of the past events in Kitimat Arm indicate that anthropogenic change (typically related to marine construction) could be a key contributing factor with respect to future landslide-generated waves if appropriate planning and engineering is not undertaken. The geomorphic record visible using the recent CHS MBES surveys shows that the two recent events are the only occurrences of large-scale, long-runout landslides in the marine environment in Kitimat Arm. The geomorphic record is interpreted to represent a period of thousands of years. This supports the conclusions of the work to date that suggest that the potential for a future naturally occurring submarine landslide capable of generating a wave is very low. The proposed Kitimat Terminal and associated marine berth are located on the western side of Kitimat Arm along a steep rocky coastline both in terrestrial and subaqueous portions of the site. Steep, straight rocky coastlines are favourable locations as they minimize potential amplification of waves that typically occurs as a result of coastal shoaling or where they become trapped in enclosed bays. The lack of significant sediment accumulation at the locations of the proposed berth sites is also favourable from the perspective of avoiding construction activities in marine sediments. Together with additional work to further refine the hazard characterization, the study concludes that suitable planning and cooperation among all existing facility owners and potential Project sponsors for all foreshore and off-shore development in the Kitimat Arm should be adopted to mitigate the potential submarine landslide hazard on the proposed project facilities. AMEC Project No. EG0926008 Executive Summary Attachment JRP IR 4.1 Northern Gateway Pipelines Inc. Kitimat Arm Landslide-Generated Wave Hazard Analysis 20 September, 2011 TABLE OF CONTENTS PAGE # 1.0 INTRODUCTION .............................................................................................................. 1 1.1 GENERAL............................................................................................................ 1 1.2 NATURE OF THE HAZARD................................................................................. 1 1.3 SCOPE OF ANALYSIS ........................................................................................ 1 2.0 DEFINITION OF A LANDSLIDE-GENERATED WAVE ................................................... 2 3.0 LITERATURE REVIEW AND SUMMARY OF EVENTS IN KITIMAT ARM ...................... 2 3.1 LITERATURE REVIEW........................................................................................ 2 3.2 SHORELINE CHANGES OBSERVED IN THE AIR PHOTO RECORD ................ 4 3.3 SUMMARY OF INFRASTRUCTURE DEVELOPMENT IN KITIMAT ARM ........... 4 3.4 REGIONAL GEOLOGY........................................................................................ 6 4.0 HISTORIC LANDSLIDE-GENERATED WAVE EVENTS ................................................. 7 4.1 GENERAL TIMELINE .......................................................................................... 7 4.2 ENVIRONMENTAL DATA ASSOCIATED WITH THE EVENTS ........................... 8 4.2.1 Kitimat River Flow ................................................................................ 8 4.2.2 Precipitation ......................................................................................... 9 4.2.3 Tides .................................................................................................... 9 4.3 17 OCTOBER 1974 LANDSLIDE-GENERATED WAVES .................................. 10 4.3.1 27 April 1975 Landslide-generated wave event ................................. 11 5.0 CHS SUBMARINE MAPPING, PROJECT SURVEYS, AND SITE SPECIFIC DATA ..... 12 5.1 CANADIAN HYDROGRAPHIC SERVICE Data ................................................. 12 5.2 KITIMAT ARM GEOPHYSICAL SURVEY .......................................................... 12 5.3 KITIMAT ARM POLYGON ATLAS ..................................................................... 13 6.0 KITIMAT ARM BASIN LANDSLIDE INVENTORY ......................................................... 13 7.0 REQUIRED FACTORS FOR LANDSLIDES TO GENERATE A LARGE WAVE ........... 14 7.1 MARINE CLAY AND MARINE CLAY LEACHING .............................................. 15 7.2 REGIONAL GROUNDWATER PATTERNS ....................................................... 16 7.3 Liquefaction ....................................................................................................... 16 8.0 TRIGGERING MECHANISMS ANALYSIS FOR THE 1974 AND 1975 EVENTS ........... 18 8.1 General .............................................................................................................. 18 8.2 Tides .................................................................................................................. 18 8.3 Geometric changes ............................................................................................ 18 8.4 ANTHROPOGENIC changes ............................................................................. 19 8.5 EVENTS RELATED TO THE 17 OCTOBER 1974 SLIDE .................................. 19 8.6 RE-VISITING THE EVENTS RELATED TO THE 27 APRIL 1975 SLIDE ........... 20 9.0 PRESENTATION OF NUMERICAL MODELING OF THE 1975 EVENT ........................ 21 A M E C Project No. EG0926008 Table of Contents Attachment JRP IR 4.1 Northern Gateway Pipelines Inc. Kitimat Arm Landslide-Generated Wave Hazard Analysis 20 September, 2011 10.0 SUMMARY OF FINDINGS ............................................................................................. 22 11.0 QUALITATIVE HAZARD ANAL YSIS SUMMARY ......................................................... 23 12.0 PATH FORWARD .......................................................................................................... 23 13.0 CLOSURE ..................................................................................................................... 25 14.0 REFERENCE LIST .......................................................................................................