Trans Mountain Attachment 1 Condition 16 Final.Docx Page Iii BGC ENGINEERING INC
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BGC ENGINEERING INC. AN APPLIED EARTH SCIENCES COMPANY TRANS MOUNTAIN PIPELINE ULC TRANS MOUNTAIN EXPANSION PROJECT QUANTITATIVE GEOHAZARD FREQUENCY ASSESSMENT – POST MITIGATION PROJECT NO.: 0095150-22 DISTRIBUTION: DATE: February 27, 2017 TMP ULC: e-copy BGC: e-copy Trans Mountain Pipeline ULC, Trans Mountain Expansion Project February 27, 2017 Quantitative Geohazard Frequency Assessment – Post Mitigation Project No.: 0095150-22 EXECUTIVE SUMMARY Trans Mountain Pipeline ULC (Trans Mountain) has retained BGC Engineering Inc. (BGC) to undertake a Quantitative Geohazard Frequency Assessment for the Trans Mountain Expansion Project (TMEP). In 2014, BGC undertook a quantitative frequency assessment of geohazards along the proposed TMEP route where the new pipeline will be constructed. The report contained herein is an update to the quantitative frequency assessment of geohazards along the proposed TMEP route. It has been updated to incorporate a review of additional data sources that were not available for the original analysis completed in 2014, data collected during site specific field assessments, and the predicted effects of site specific mitigations. The purpose of the assessment is to evaluate each potential geohazard with respect to its ability to impact the Line 2 and result in loss of containment (LoC). Results from this updated analysis were used as part of a broader hazard and risk assessment for the proposed pipeline and associated infrastructure (to be carried out by others), to identify areas for further study or that require additional mitigations, and to fulfil Condition 16 of OC-064. For this assessment, a systematic procedure was used to assign quantitative values to qualitative parameters that describe each potential geohazard site to estimate the frequency of a LoC (FLoC) event for the pipeline due to geohazards. The approach is considered appropriate for the intent described above where historical data associated with the frequency, spatial impact, and vulnerability of the individual geohazards must be supplemented with subjective estimates of probabilities (through engineering judgment). The broader pipeline hazard and risk assessment requires a numerical estimate of the FLoC from geohazards that can be compared with FLoC estimates for other threats to the pipeline that are being prepared by others. Similar approaches for geohazard analyses have been employed by other large-scale oil and gas development projects in Canada, including the Mackenzie Gas Project (submitted to the National Energy Board in 2004) and the Northern Gateway Project (submitted to the National Energy Board in 2010). The geohazard frequency assessment method uses six factors that provide a numerical value for the FLoC in terms of events per year from a geohazard for a specific location along the pipeline. The factors include Occurrence (I), Frequency (F), Horizontal Spatial (SH), Vertical Spatial (SV), Vulnerability (V), and Mitigation (M) and the basis for each of the factors is described in the body and appendices of this report. The equation used to estimate the FLoC from a geohazard, at a specific location along the pipeline denoted with the subscript (i), is as follows: FLoC(i) = I(i) x F(i) x SH(i) SV(i) x V(i) x M(I(i),F(i),SH(i), SV(i),V(i)) The updated geohazard assessment was completed on the Route SSEID 005 alignment. The previous version of this report was based on the Route Version 9 corridor that was filed in Technical Update No. 1, August, 2014. This updated report includes recently identified Trans Mountain Attachment 1 Condition 16 Final.docx Page iii BGC ENGINEERING INC. Trans Mountain Pipeline ULC, Trans Mountain Expansion Project February 27, 2017 Quantitative Geohazard Frequency Assessment – Post Mitigation Project No.: 0095150-22 geohazards based on site specific fieldwork or a review of complete LiDAR coverage along the alignment. The geohazards assessed in this report include soil, rock, and hydrotechnical hazards. The National Energy Board’s (NEB) Condition 16 of OC-064 requires: Trans Mountain must file with the NEB, at least 6 months prior to commencing construction, an updated Quantitative Geohazard Frequency Assessment for the Line 2 and delivery pipeline segments that contains a re-assessment of the Frequency of Loss of Containment (FLoC) values based on the results of site-specific field assessments and any required mitigation as determined in the detailed engineering and design process. Trans Mountain must provide in the assessment a plan to manage and mitigate geohazards at any location where the FLoC is greater than 10-5 events per year to reduce the level of risk to as low as reasonably practicable (ALARP), including a detailed explanation of how ALARP level has been attained at each location. The NEB has indicated that Trans Mountain must provide a plan to manage and mitigate geohazard locations that have a FLoC value greater than 10-5 events per year to reduce the level of risk to as low as reasonably practicable (ALARP). The FLoC value of 10-5 is hereinafter referred to as the “threshold” value for the purposes of this report. This assessment incorporates the anticipated effects of mitigation designs on FLoC values that have been applied for geohazard sites that have a pre-mitigated FLoC greater than 10-5. The mitigation measures reduce the FLoC value at each site by modifying one or more of the FLoC factors. A range of modification values for each of the factors for the potential mitigation measures are provided in Appendix A. The range in the mitigation values in Appendix A represent the expected reduction in the FLoC factor if the proposed mitigations are applied during construction. Of the 1,569 credible geohazard segments, 220 have pre-mitigated FLoC values greater than 1 x 10- 5 events per year. The application of mitigations reduces the number of segments that will have a FLoC greater than 1 x 10-5 events per year to 40, with the remaining 180 segments having a FLoC value equal to or less than 1 x 10-5 events per year. Of the 40 segments, 27 of the segments are related to rock slope geohazards, one segment is a soil slope geohazard, and the remaining 12 segments are hydrotechnical hazards. Table 5 and Appendix D contains a summary of the 40 segments along with methods for reducing these sites to ALARP. Trans Mountain Attachment 1 Condition 16 Final.docx Page iv BGC ENGINEERING INC. Trans Mountain Pipeline ULC, Trans Mountain Expansion Project February 27, 2017 Quantitative Geohazard Frequency Assessment – Post Mitigation Project No.: 0095150-22 TABLE OF CONTENTS EXECUTIVE SUMMARY ...................................................................................................... iii TABLE OF CONTENTS ........................................................................................................ v LIST OF TABLES ................................................................................................................. vi LIST OF FIGURES ............................................................................................................... vi LIST OF APPENDICES ........................................................................................................ vi LIMITATIONS ...................................................................................................................... vii 1.0 INTRODUCTION ......................................................................................................... 1 2.0 GEOHAZARD FREQUENCY ASSESSMENT METHODOLOGY ................................ 2 2.1. Risk Assessment Framework .................................................................................. 2 2.2. Definitions and Key Concepts ................................................................................. 2 2.2.1. Hazard .............................................................................................................. 2 2.2.2. Hazard Identification ......................................................................................... 2 2.2.3. Risk .................................................................................................................. 4 2.3. Geohazard Frequency Analysis .............................................................................. 4 2.3.1. Occurrence Factor (I) ........................................................................................ 5 2.3.2. Annual Frequency of Geohazard Occurrence (F) .............................................. 5 2.3.3. Horizontal Spatial Probability of Impact (SH) ..................................................... 6 2.3.4. Vertical Spatial Probability of Impact (SV) .......................................................... 6 2.3.5. Vulnerability (V) ................................................................................................ 6 2.3.6. Mitigation (M) .................................................................................................... 6 2.3.7. FLoC Uncertainty .............................................................................................. 7 3.0 TMEP GEOHAZARD FREQUENCY ASSESSMENT .................................................. 9 3.1. Geographic Extent of Assessment ......................................................................... 9 3.2. Data Sources and Assessments Used in the Updated Geohazard Analysis ........ 9 3.3. Geohazards Assessed ........................................................................................... 11 3.4. Other Geohazards .................................................................................................