Report - Agence canadienne d'évaluation environnementale

Impacts on the inhabited area and human activities
the highest of the following sound levels, 45 dBA (Leq 1 h) or the level of initial ambient
noise if it is more than 45 dBA. During daytime, (7 a.m. to 7 p.m.), the equivalent
noise level (Leq 12 h) must be equal to or less than the highest of the following sound
levels, 55 dBA or the level of initial ambient noise if it is more than 55 dBA. In
exceptional circumstances, a departure from this could be allowed during the day or
evening (Leq 3 h of 55 dBA from 7 p.m. to 10 p.m.), but none would be acceptable at
night.
For the operation phase, according to the MDDEP criteria applicable to sources of
sound in proximity to rural homes, the equivalent hourly sound levels (Leq 1 h) must not
exceed 40 dBA at night (7 p.m. to 7 a.m.) and 45 dBA during the day (7 a.m. to 7 p.m.),
or the initial ambient sound level if it is higher than these criteria. The proponent
estimates that the applicable noise level at the property limits of the new proposed
facilities would correspond to a Leq 1 h of less than 70 dBA. In regard to noise outside
homes, the proponent will follow the MDDEP guidelines. The proponent also stated that
these limits could be replaced by the initial level of ambient noise, if it is higher, which
conforms to the MDDEP approach.
In the city of Lévis, zoning by-law no. 234, section 3.3, states that at the limit of the
area, there should be “no noise more intense than average intensity for the level of
noise around the street and passing traffic.” In terms of the maximum intensity
permitted, the proponent states that the criteria used do not correspond to current
practice, but that it would correspond to a Leq of 65 dBA at the limit of the area, and do
not offer any adjustment for the construction period. For its part, the municipality of
Beaumont does not deal with noise in its by-laws.
The current sound environment
The proponent measured the ambient sound level, prior to project execution. This
initial sound environment was measured using sound samples from 23 different
locations. Of these 23 measuring stations, only one was located on île d’Orléans, the
proponent considering this location to be representative of the quiet areas on the
southern part of the island. Moreover, the measuring station locations were chosen to
represent sensitive areas where noise is concerned (residential areas) and to take
existing noise conditions for all the planned project building sites. Measurements of
sound levels were taken over 20-minute periods and extrapolated to 60 minutes as
the sound level was stable (Leq 1 h: hourly average), day (7 a.m. to 7 p.m.) and night
(7 p.m. to 7 a.m.). In order to take major noise sources into account as well, samples
were taken continuously over 24 hours in proximity to Highway 132 and
Expressway 20. The measurements were taken using state-of-the-art rules applicable
to both distances and climatic conditions (PR3.3.1, p. 2.116; PR5.1, p. 3.63).
182 Rabaska Project – Implementation of an LNG Terminal and Related Infrastructure