Stantec Consulting Ltd. (Stantec), by request from BP Canada Energy Group ULC (BP), has engaged JASCO Applied Sciences (JASCO) to perform acoustic field modelling of underwater sound levels associated exploratory well activities within the Scotian Basin Exploration Drilling Project (the Project). The area of interest spans exploratory license blocks EL-2431, 2432, 2433, and 2434. Two hypothetical well sites on the continental slope in water deeper than 2000 m were modelled (Figure 1). Proposed activities at the sites that would generate underwater sound, and that are modelled in this study, are exploratory well drilling and Vertical Seismic Profiling (VSP). The specifics of vessels and the seismic source are unknown at this time. A drillship (DS) or a semi-submersible platform (SS) could be used; therefore, both of these sound sources were modelled. A support vessel (SV) that will be present during drilling was also modelled. The VSP survey will be performed with a VSP airgun source array. Multiple scenarios were modelled at each of the two sites to cover different configurations of the acoustic sources, as well as the seasonal variations of the propagation conditions. The modelling methodology accounts for source characteristics and for local environmental properties. Model results are presented as root-mean-square (rms) sound pressure levels (SPLs), peak SPL, and cumulative sound exposure levels (cSELs). The SELs were calculated after the M-weighting filters of Southall et al. (2007) and NOAA (2015) were applied. The acoustic modelling results were compared to various sound level threshold criteria associated with potential injury and behavioral disturbance in order to assess the ranges from the source at which such potential effects may occur, based on: – Injury o Southall et al. 2007 metrics, in both, peak SPL and cSEL o NOAA 2015 draft metrics, in both peak SPL and cSEL – Behavioural o NOAA interim 120 dB rms SPL for non-pulse/continuous acoustic sources (i.e., vessels) o NOAA interim 160 dB rms SPL for pulse/impulsive sources (i.e., VSP) Section 1.2 presents background information on various metrics commonly used to characterise underwater sound. The acoustic threshold criteria associated with potential impacts are discussed in Section 1.3. Section 2 discusses the methods used to estimate the source levels and model the sound propagation. Section 3 details the acoustic sources that were modelled and describes the environmental parameters used in the propagation model. Section 4 presents the model results in two formats: (1) tables of distances to sound level thresholds and (2) sound field contour maps showing the directivity of the various sound level threshold contours. Section 5 provides a discussion of model prediction validity and the factors influencing sound propagation.
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