What’s that smell at Vail’s Covered Bridge?
For over two decades, the town has battled the odor near the Covered Bridge, trying out various solutions
On certain winter days, pedestrians entering Vail Village through Slifer Square and the Covered Bridge might notice a smell permeating the area. And it’s not a new smell — the town of Vail has experienced this issue on and off for over two decades.
“The smell is back at the Covered Bridge,” reported Vail Town Council member Jen Mason at the Jan. 3 Town Council meeting. Over the past few months, the return of the smell has been addressed by various other Council members, including as recently as Tuesday, March 7.
So, where is the smell coming from?
Tom Kassmel, the town engineer, said the odor comes from the storm sewer and quality vaults that exist underground in the plaza. And while the smell is normally kept within the vaults, a warm winter day can cause it to rise above ground.
“When the vault air is warmer than the air outside, the warm stagnant air flows up and out through the storm sewer and out into the plaza through the storm drain inlet grates,” Kassmel said.
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Vail owns and maintains over 30 of these water-quality vaults in town. However, Kassmel said this is the only one in which the town has this smell issue. The reason is that the sewer and vault below Slifer Square capture the water runoff from the Frontage Road and Vail Village Parking Garage, which is “laden with mag chloride, oils, sands, salts, heavy metals and other debris,” he added.
These pollutants are captured in the vaults until cleaned out and “stagnate and stink,” Kassmel said.
“The assumption is that it is the amount of use and pollutants that enter the parking structure from vehicles and that the garage is fully enclosed and maintains a warm air temperature unlike the open-air garage at Lionshead,” he said.
While warm weather in the winter causes the smell to emerge, it’s not an issue in the summer when the “air temperature in the water quality vaults is cooler than the outside air and not as many pollutants enter the vaults,” according to Kassmel.
For over 20 years — since the first water quality vault was installed below the square — the town has dealt with this smell and tried to mitigate it in various ways.
Mitigation efforts included installing a charcoal filter to a manhole, replacing a low point in the sewer pipe that held stagnant water, using aeration tablets to mitigate stagnant water, adding a forced air venting system to the vault, and increasing the frequency at which it cleans the vaults.
And yet, the smell persists.
“All of these efforts have reduced the frequency, but after a significant snowmelt event, like a warm sunny day, and when the air in the vault is warmer than the outside air, the smell persists,” Kassmel said.
So, the search for solutions continues, some of which carry more promise than others.
Specifically, Kassmel said that while bypassing these vaults to remove this stagnant water is a “potential option” to remove pollutants, this would mean the pollutants would go directly into Gore Creek, rendering the option “unacceptable.”
“The next step may be to add a powered aerator in the vaults, similar to what you may see in stagnant ponds,” Kassmel said.