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Phase 2 Noise Modelling Study Predicts Same Problems as Existing Track

The long-awaited report on the acoustical modelling study commissioned by the Vancouver Island Motorsport Circuit (VIMC) for their planned track expansion has now been released. The Sahtlam Neighbourhood Association has reviewed the report, which effectively says that the planned 230-acre expansion will produce no more noise than the existing facility. Unfortunately, the existing facility is already a nuisance, as evidenced by ongoing and widespread noise complaints. Thus, the report on Phase 2 (the planned expansion) shows that noise will continue to be a problem if the rezoning goes ahead as planned.

The report on the Phase 2 noise modelling study is, in many places, copied verbatim from the report for Phase 1 (the existing facility). Importantly, the same premise is put forward in both reports: that an Leq(15min)* of 60 dBA (A-weighted decibels) measured at the nearest residence to the track, is an acceptable standard. The SNA categorically rejects this as an appropriate target for noise mitigation.

According to the VIMC noise reports, the justification for this number is that the Cowichan Valley Regional District noise bylaw states that "continuous noise" cannot exceed 60 dB during daytime hours. The SNA disputes the interpretation of the CVRD Noise Bylaw as described in the Phase 1 and 2 reports, particularly the interpretations of "continuous" and "non-continuous" noise. Regardless, the CVRD noise bylaw does not apply to industrial or commercial noise and was not designed to deal with racetrack noise. Therefore the SNA rejects the CVRD noise bylaw as an appropriate guideline for managing track noise from VIMC. Furthermore, the SNA rejects using an equivalent noise level of 60 dBA as the standard toward which VIMC should direct their mitigation efforts.

There are two main reasons why the SNA rejects a noise mitigation target of Leq(15min) = 60 dBA at the nearest residence to the track. First, equivalent sound levels are effectively an average**. But residents don't experience track noise as an average, they experience it in real time: engine sounds rise and fall as the cars navigate various sections of the track. Sound levels during the loudest periods are an important factor in the degree of intrusiveness, as are the intermittent and fluctuating levels of sound. Thus, an equivalent sound level will not accurately reflect the nature or severity of the noise as experienced by listeners. Importantly, an Leq (such as 60 dBA) gives no indication of the range of noise levels that result in that number.

The second reason why the SNA objects to a noise mitigation target of Leq(15min) = 60 dBA at the nearest residence to the track, is due to the way sound travels through the area. Highway 18, which is arguably the dominant source of ambient noise in the affected areas of Sahtlam, sits at an elevation of approximately 100 meters above sea level. Directly south of the highway, at the end of Mina Drive, the land rises up steeply. This, along with other elevation changes further south, significantly attenuates highway noise as it travels away from the road. This is evident in the Phase 1 and 2 noise reports, where highway noise is shown to decrease significantly with distance from the highway.

On the other hand, as shown in the Phase 1 and 2 noise reports, track noise carries far and wide throughout the region. The track is built on a hill, and the top of the track sits about 120 meters above sea level, far above the highway and with a clear line of transmission across the valley. Thus, unimpeded noise from VIMC carries much farther than highway noise. As a result, the nearest residence to the track (which is the reference point of reception being used by VIMC) is the LEAST affected by track noise, because it sits on the side of Highway 18 and ambient noise levels there are already high. In addition, that residence is low down, next to the highway, and so sounds from higher track elevations are largely muffled by highway noise. In contrast, residents at the end of Sahtlam Road (for example) experience very little highway noise, but experience high levels of track noise. The difference between ambient noise and track noise (which is a critical factor in the degree of intrusiveness) is much higher at residences further away from VIMC.

All of this information is supported by data from the Phase 1 and 2 modelling study reports.

Another indicator that an equivalent sound level of 60 dBA is not "the magic number" is the ongoing issue of noise complaints. This past Easter long weekend brought a flurry of emails and phone calls to the Municipality of North Cowichan, and that was only the most recent example of such occurrences. Excessively loud noise days continue to happen regularly. Adhering to the recommendations in the Phase 1 noise report has clearly failed to adequately address the noise problem in Sahtlam due to a number of factors, including those described above.

In summary, given that the recommended noise levels arising from the Phase 1 noise modelling study have proven to be a failure, and given that the Phase 2 report provides the same recommendations, we have no confidence that the noise problem will be any better with an additional 2 km of race track rising up another 55 meters in elevation. It is our position that VIMC needs to come up with appropriate noise mitigation for Phase 1 before North Cowichan considers allowing them to proceed with track expansion.

* Leq(15min) is the equivalent sound level measured over a 15-minute period

** decibels follow a logarithmic distribution, and therefore a true average decibel level cannot be calculated; instead, monitoring software uses measurements of sound pressure, which are not logarithmic, calculates the average, and then converts the average to dB

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