UTVs lined up in a row ahead of a past Rally on the Rocks trail ride near Moab. In 2017, the event drew an estimated 1,200 registered participants to the area. [Moab Sun News file photo]

Grand County officials are continuing to pursue strategies to reduce noise from traffic, especially from OHVs, after a new state law struck down recent amendments to the county’s business licensing regulations. At its May 17 meeting, the county commission heard a presentation from noise consultant Les Blomberg, of the nonprofit Noise Pollution Clearinghouse, on the science of sound and the results of recent local noise monitoring.

Blomberg explained that because the range of human hearing is so large—people can hear very, very quiet sounds and very loud sounds—scientists created the decibel unit using a logarithmic scale, which compresses that range. Instead of using a scale that ranges from 20 to 20 million, the decibel scale ranges from zero to 120.

“You don’t need to know anything about logarithms—all you need to know is that this makes understanding noise a little difficult,” Blomberg said. Using the decibel system, he explained, two sounds that are both 50 decibels don’t add up to 100 decibels—they add up to 53 decibels.

Blomberg also pointed out some aspects of the Moab area that make it particularly prone to noise pollution. There are a lot of hard, reflective surfaces, such as the cliff faces above the valley, that can reflect noise, effectively acting as an additional noise source. The dry climate also facilitates noise pollution: there are fewer trees to act as sound barriers, and there is less soft, textured build-up of organic matter on the ground, leaving the ground to act as another hard, reflective surface.

“You guys have both a very unique acoustic environment that is worthy of protection and very easy, with noise, to ruin,” he said.

Last week, Blomberg monitored noise on the Sand Flats road using a 50-foot drive-by test, taking measurements of noise produced by UTVs, Jeeps, trucks, motorcycles, and cars. He displayed a graph showing that out of 67 data points, nine were over the county’s noise threshold of 74 decibels for a 50-foot drive-by test.

“This is really dependent on how much gas they give it and the condition of their exhaust system,” Blomberg said, in contrast to the 20-inch tailpipe test, which is more of an equipment measurement.

Six of the vehicles exceeding the threshold were UTVs, one was a Jeep, and two were motorcycles.

Commissioner Jacques Hadler attended the monitoring session, and said he was struck by how closely noise levels are associated with the speed a vehicle is driving.

“The faster vehicles were moving, absolutely increased the noise from those. So enforcing speed limits, I think, would go a long way towards helping out with the noise problem,” Hadler said.

County Attorney Christina Sloan said that the county has received several emails suggesting the purchase of stationary sound monitors. Some larger cities have such devices; some are used only for educational and monitoring purposes, and some are designed to issue tickets to violators. Blomberg said a stationary sound monitor could be a good tool for Grand County for educational purposes, but using such devices for issuing citations is difficult to set up and enforce.

Blomberg trained Grand County Sheriff’s officers on how to conduct the 50-foot drive-by tests. Sloan said the training has been productive and helpful for sheriff’s officers.

“I think we worked through some of their hurdles with the way they would statutorily cite things, or cite things under statute versus local ordinance,” Sloan said. House Bill 146, the law that struck down the county’s business regulation amendments, she noted, did make it clear that state law supports noise ordinance enforcement, which is helpful to officers.

“They were very receptive to some of the information,” Sloan said. “Even by providing an overview of all the noise comments and complaints we’ve received from the community for the last couple of years—that was news to a lot of these folks in the sheriff’s office.”

Sloan agreed that enforcement of speed limits could be helpful, as well as licensing and registration enforcement. 

“One of our deputies impounded a non-licensed ATV for the first time this weekend after the noise training,” Sloan said. 

However, she said that peripheral issues like speed are like symptoms of the problem, where noise is the cause. 

“It’s really important to treat the cause as well,” she said.