Report - Agence canadienne d'évaluation environnementale

Assessing the risks related to the project
In the event that a natural gas cloud would disperse without immediate ignition, then
this cloud could ignite later on upon coming into contact with an ignition source, thus
resulting in a fire. In such a case, then the distance to the lower flammability limit for
accident scenarios using a 750-mm breach would be 1,100 m. In the case of an
intentional act, ignition would be immediate and the natural gas cloud would not be
dispersed (PR5.3.2, p. 7).
♦ Finding — The Panel found that, in the case of the worst-accident scenarios involving
a berthed LNG tanker with a 1,500-mm breach, it would be possible for individuals to
be inside the impact area of a fire fuelled by a liquefied natural gas pool in the Lévis-
Beaumont sector.
♦ Recommendation 5 — The Panel recommends that, when planning emergency
measures, the proponent should provide Environment Canada and the ministère du
Développement durable, de l’Environnement et des Parcs with an analysis of sensitive
elements when considering an accident scenario for a berthed LNG tanker, on the
basis of criteria using a 1,500-mm breach, a steady-state pool and a 3-kW/m 2 thermal
radiation threshold.
Accident scenarios for land facilities
According to the MDDEP, the accident scenarios considered by the proponent in
regard to land facilities are acceptable, and the impact study provided sufficient
information for the Ministry to continue its environmental assessment of this aspect
(Mr. Pierre Michon and Ms. Marie-Claude Théberge, DT4, p. 65 and 79). Table 10
details the main results of these four scenarios.
The proponent identified the sensitive elements within the 1.6-kW/m 2 thermal radiation
isocontour. According to the analysis, no residence or other sensitive element would
be found within this thermal radiation limit, regardless of the accident scenarios
considered (DQ99.1, p. 3).
The proponent also assessed the possibility of an accident occurring at the terminal’s
facilities that could affect the pipeline’s integrity; according to him, this type of event is
unlikely, if not impossible (DQ17.3).
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