Report - Agence canadienne d'évaluation environnementale

Impacts on the inhabited area and human activities
According to the proponent, the measured sound levels (Leq 1 h), varied between
40 and 62 dBA during the day and between 33 and 58 dBA at night in the inhabited
areas. Rue Vitré is the quietest spot at night. Traffic not only on Highway 132 and
Expressway 20, but also on the rue de l’Anse (western access to Expressway 20) and
Lallemand Road (eastern access to Expressway 20) and the chemin Saint-Roch is
the main cause of noise. Some other selected noise sources were itemized, but
without influencing hourly measurements.
According to the proponent, the sound climate are already disturbed in the zone
considered for the gas pipeline area by industrial activity, an airport, railways,
Expressway 20 and several stretches of road.
♦ Finding — The Panel notes that the present sound environment occasionally
exceeds the criteria set by the ministère du Développement durable, de
l’Environnement et des Parcs close to the main roadways on the basis of Leq 1 h.
The rue Vitré area is described as quiet at night.
Noise impact related to the LNG terminal
Noise impact during construction
Projected sound levels during construction and operation were calculated using the
method described in the standard ISO 9613-2. This makes it possible to predict sound
level in weather conditions that are favourable to the spread of noise, such as a
carrying wind (i.e., from the source toward the receiver) or with a moderate
temperature inversion like that which commonly occurs at night. The method takes
into account the sound power, the dampening effect of obstacles (buildings, drop in
terrain level, etc.), geometric dispersion, absorption by air, ground effects and
reflection off surfaces. (PR3.3.1, p. 6.89).
The main sound impacts during terminal construction would be due to machinery on the
building site – mechanical shovels, cement mixers, cranes, and trucks, as well as pile
driving at the jetty. In the main, these activities would be spread out over about 24 months,
including slowdowns and halts during winter periods. Construction of LNG storage tanks
would be carried out continually 24 hours a day while pile driving for construction of the jetty
would take place only during the day (PR3.3.1, p. 4.103, 4.104 and 6.95).
Over and above the noise impacts of trucks on the site, the noise impacts of trucks
moving along public arteries near the site, either Lallemand Road, rue de l’Anse, or
Highway 132, were also assessed. Along with construction site noise, the intensity of
noise effects from truck traffic on public arteries was described as average (ibid.,
p. 6.99-6.101; PR5.1, p. 2.7).
Rabaska Project – Implementation of an LNG Terminal and Related Infrastructure 183