Science Response 2015/027

Technical review of 3D modelling of potential effects of marine structures on site hydrodynamics and sedimentation from the construction of the Pacific Northwest liquefied natural gas terminal

Context

Pacific NorthWest Liquid Natural Gas (PNW LNG) is proposing to construct a large scale liquefied natural gas (LNG) export terminal within the Skeena River estuary (Figure 1) (hereafter referred to as the ‘Project’).  The Project will require dredging, blasting and pile driving to construct a suspended trestle and terminal berths.

On April 8, 2013 the Canadian Environmental Assessment Agency (the Agency) issued a Notice of Commencement that they had commenced an environmental assessment pursuant to the Canadian Environmental Assessment Act (CEAA 2012) for the PNW LNG project located on Lelu Island, BC.

The Environmental Impact Statement (EIS) and Addendum submitted by PNW LNG to the Canadian Environmental Assessment Agency (CEAA) on 28 Feb 2014 and 12 Dec 2014, respectively, provided information with regard to potential effects of marine operations and marine structures upon the sea bed and habitat at Agnew and Flora Banks (Figure 2). The Addendum also provided detailed responses to Information Requests posed by the Government of Canada in regard to sediment deposition; including a report that provides a sediment transport and deposition analysis that utilized 2D models (e.g., USCGA CMS and PTM ) conducted by PNW LNG’s marine engineering consultant, Hatch.

On Feb 23 2015, PNW LNG received a new Information Request from CEAA, requesting additional 3D hydrodynamic and sedimentation modelling. A Terms of Reference was developed to guide the additional assessment (Hatch, 2015 – Appendix A).
DFO Science Branch provided informal advice to DFO Fisheries Protection Program on draft pre-construction and post construction modelling undertaken by the proponent to assess the potential effects of marine operations and marine structures upon the sea bed and habitat at Agnew and Flora Banks.  On May 5, 2015, the Fisheries Protection Program requested that DFO Science review the final results from the above mentioned modelling exercise to support the development of DFO’s response to CEAA.

The objective of this Science Response is to review information provided with respect to the above mentioned modelling in the Proponent’s May 5, 2015 submission “Pacific Northwest LNG - 3D Modelling of Potential Effects of Marine Structures on Site Hydrodynamics and Sedimentation” (Hatch, 2015), and to answer the following questions by May 19, 2015:

1. Can DFO Science comment on the level of uncertainty in the 3D model and implications for model accuracy?
2. What is DFO Science’s view of the model results?

This Science Response Report results from the Science Response Process of May 19, 2015 on the Technical review of 3D modelling of potential effects of marine structures on site hydrodynamics and sedimentation from the construction of the Pacific Northwest liquefied natural gas terminal.

Complete document (PDF, 368 KB)

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