Why is hazard zone assessment along the tanker route important?

The three hazard zones shown on the map are drawn directly from the US Department of Homeland Security | US Coast Guard guidelines outlined in their LNG Terminal Waterway Suitability Assessment (WSA).  In the United States, proponents wanting to build a waterfront LNG terminal facility must conduct a WSA in order to receive federal approval.  Hazard zone assessment must be applied to the proposed site of the LNG terminal, as well as to the LNG tanker route. (View an interactive version of the hazard zone map here.)

No such requirement exists in Canada.  In fact, the US company behind the Tilbury Island LNG proposal, WesPac Midstream, explicitly disavows responsibility for conducting such an assessment:

WesPac will require vessel operators to comply with all applicable national and international safety requirements when at the Project.  However, responsibility for the care, safety and control of the LNG carriers, LNG barges and, upon loading, the LNG product will generally lie with the receivers and with the vessel operators. (pg. 17, project summary description)

Further, WesPac Midstream’s project summary description for the Tilbury LNG proposal does not explicitly consider the possibility of an intentional act (i.e. an act of terrorism) leading to the loss of LNG containment.  Such an analysis is required by DHS | USCG in the United States.

Our region deserves better.  During the scoping phase of the environment assessment for this project we must demand that Ottawa incorporate a Waterway Suitability Assessment into the federal EA, so that risks to public safety and property along the proposed LNG tanker route, from the terminal to international waters at Canada’s territorial sea limit, can be properly assessed.

What risks do the hazard zones represent?

The WSA guidelines are based on a report completed by Sandia National Laboratory in the United States, Guidance on Risk Analysis and Safety Implications of a Large Liquefied Natural Gas (LNG) Spill Over Water.  The purpose of the Sandia report was to estimate the hazards that would be generated by a worst case scenario: the intentional breach of containment of an LNG tanker up to 265,000 m3 capacity.  While the likelihood of such an event is low, the consequences are severe.

The hazard zones shown on the map are schematic overlays; in real world applications the proponent would have to account for variations in terrain and the influence of structures through dispersion modelling.  The 500m, 1600m and 3500m zones reflect the following hazards, in addition to others:

  • 500 m zone: extreme hazard of combustion and thermal damage from intense heat of pool fire if evaporating LNG is ignited.  Further hazard from cryogenic burns and structural damage from exposure to supercooled LNG. Asphyxiation hazard for those exposed to expanding LNG vaporization plume.
  • 1600 m zone: hazards as for the 500 m zone, with severity of consequences declining over distance.
  • 3500 m zone: conservative maximum distance within which an expanding LNG vapour cloud may still ignite if in contact with a source of ignition.  Resulting fireball would burn back to the spill source and could result in intense pool fire at the tanker.

The LNG tanker route for the Fraser River LNG proposal was compiled from two sources: Lists of Channels and Reaches, Fraser and Pitt Rivers (Vancouver Fraser Port Authority) and WesPac Tilbury Project Summary Description (pg 65 – outbound route from Sand Heads to international waters)

The DHS | USCG Waterway Suitability Assessment further describes the hazard zones as follows (page 50 in WSA):

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