Confusion over Vancouver Island Motorsport Circuit sound limits explained
After a heated local council meeting led to confusion about racetrack sound limits, experts cut through the noise.
On Wednesday, Aug. 21, Municipality of North Cowichan council gave first and second reading to an application from the Vancouver Island Motorsport Circuit (VIMC) to rezone its property and make way for a major expansion of the controversial facility. At the heart of the conflict is disagreement over what would be an appropriate sound limit for the racetrack.
The council meeting would normally be a rather boring procedural event. But this meeting was not ordinary. Council had to change the location from the usual council chambers to the Duncan Ramada ballroom. It expected a lot of people to show up.
And they were right — hundreds of people came. Some were prompted by fliers sent in the mail by the Vancouver Island Motorsport Circuit, encouraging residents to show support. Ten or so staff from VIMC wore T-shirts with the company logo on the front. The backs read, “I need to feed my family! Don’t put me out of work! Save our jobs!”
The Vancouver Island Motorsports Circuit, located close to Duncan B.C., is, essentially, a racetrack, though no competitive races are held at the facility. VIMC calls itself a “motorsports playground,” and a “test facility for vehicles and drivers.”
A tense meeting
Mayor Al Siebring had to remind the audience on a few occasions to refrain from applause or other displays of support or displeasure, to avoid possibly intimidating those with a different view.
So why all the tension? Noise. The company wants to spend $39 million to double the existing length of its track and add other new features to the facility. Neighbours close to the track say the facility has significantly interfered with the enjoyment of their properties and expanding it would make that even worse.
At the meeting, frustration ran high as Mark Holland, a consultant hired by VIMC, presented new information on a proposed sound limit. But Councillor Christopher Justice’s understanding of the sound limit didn’t line up with what VIMC representatives said about it. He asked several questions and confusion ensued. Everyone agreed that clarity was needed, but it was not offered.
So, I’ve been doing my own homework to figure out just what this proposed sound limit means. I’ve spoken with acoustics experts, on the phone and by email, who are not associated with this project. I’ve read up on sound, too, including technical documents, noise bylaws, and legal judgements. Here’s what I’ve found.
What is being proposed?
Holland said the company plans to spend a million dollars on sound barriers to limit noise in the neighbourhood. He said the track would limit operating days and hours. He said that, normally, only street-legal vehicles would be allowed on the circuit. And he said VIMC would voluntarily limit sound to “59 dB LA20, 15min” as measured from sound meters stationed in the neighbourhood.
Now, bear with me. That string of letters and numbers looks like nonsense to the vast majority of people on this planet. And it did to me a week ago. But it’s important. That’s the noise standard that VIMC is proposing to hold itself to (with exceptions for up to six “special events” days annually, and any time the Vancouver Island Karting Association uses the facility.)
What does it actually mean? How does this standard compare with what neighbours experience now?
I called Chris Erb, a contractor to VIMC who is leading the rezoning application, after the meeting. He offered to help connect me with VIMC’s sound expert or someone else who could help answer my questions. But he didn’t respond to my attempts to follow up. No one from VIMC or its representatives responded further to my requests for comment on this article.
What does it actually mean?
At the meeting, Councillor Justice described his understanding of “59 dB LA20, 15min” this way. This means that the noise level, measured from within the neighbourhood, would have to be below 59 decibels for at least 12 minutes in any 15-minute period. However, for up to three minutes out of those 15, the noise could be any level at all.
This is correct. Hugh Davies, a professor of environmental acoustics at the University of British Columbia, confirmed to me by email that this fits his interpretation.
Representatives for VIMC at the meeting insisted several times that the measurement system that they are proposing indicates an average. The average sound level would be kept below 59 decibels, they said. This is not correct, Davies says. He says the average sound level would greatly exceed 59 decibels in a hypothetical scenario where the sound level is at or just below 59 decibels for 12 minutes and well above that for just under three minutes.
How did they come up with that?
Both VIMC and North Cowichan say they picked this way of limiting sound because it is consistent with limits set out in the Cowichan Valley Regional District’s noise control bylaw. VIMC is not in the CVRD’s jurisdiction, but many of the residences where complaints are coming from are.
But applying the bylaw in the way that they appear to have done here is “a stretch,” says Tony Hoover, a principal consultant with the acoustics firm McKay Conant Hoover Inc. They are applying the rules for “continuous noise,” which usually refers to things with a constant sound level like an air conditioner or fan.
Using LA20 is an unusual way to measure sound, he adds.
Is the limit acceptable?
“If I was really trying to do service to those who might be concerned with the noise from any given kind of facility, whether it’s a racetrack or not, I would be very interested to know what is the background sound without the facility operating compared to the sound of the facility operating,” Hoover says.
That’s because sound tends to be more annoying if it’s loud relative to the context it’s in, Hoover tells me. Imagine someone listening to loud music through their headphones at the library, versus on an airplane.
Some noise ordinances take this into account by using relative sound limits, Hoover says. That would set a number of decibels a sound can be over the background noise. It’s common to see a relative limit of 10 decibels, he says. An increase of 10 decibels roughly means that a person will consider the sound to be twice as loud.
VIMC has not shared real data for background noise from the neighbourhoods near the track. But it did pay for a noise modelling study, which uses a computer model to predict noise impacts of the current and proposed future track.
The study modelled sound impacts from Highway 18 as a proxy for background noise in the neighbourhood. It found that on a very busy track day, noise from VIMC would exceed noise from the highway by as much as 22 decibels at certain locations. That means the track would sound more than four times as loud as the highway from that spot.
“If I hear this other sound that’s significantly louder than my background sound and know that it’s going to happen again, and again, and again, that’s usually cause for concern,” Hoover tells me.
What we don’t know
We don’t know the actual background sound levels are in the neighbourhood. Or if the current noise impacts from the track’s operations. We don’t know if the proposed sound limit would allow the facility to emit more or less noise than it currently does.
VIMC’s noise modelling study and other documents relevant to the rezoning can be found on the Municipality of North Cowichan’s website. North Cowichan paid for a peer review of VIMC’s sound study but has not made that report public. The Sahtlam Neighbourhood Association confirmed to The Discourse in an email that it has completed its own sound study. It recently submitted that report to North Cowichan for review.
It’s unclear what information the public will get a chance to see before the municipality makes a call on the rezoning. But in any case, members of the public will have a chance to weigh in. There is a public hearing scheduled for Oct. 1 at 6 p.m. at the Cowichan Performing Arts Centre.