Road sand eyed in air-pollution reduction

By Greyson Howard, Sierra Sun
12:01 a.m. PT Sep 25, 2007

First, the Town of Truckee targeted old wood-burning stoves in an effort to improve the air quality of the mountain community.

Now, road sanding may be next air-quality threat in the town's cross hairs.

Truckee's seventh annual Particulate Matter Air Quality Report shows improving trends in particulate air pollution as a result of the town's woodstove change-out program. Newer stoves reduce the amount of fine particulates (under 2.5 microns) discharged into the atmosphere.

But while the town has reduced the amount of fine particles in the local airshed, Truckee exceeded national and state standards for coarse particulates of 10 microns or greater from 2004 to 2006.

The courser particles are generated primarily by road sanding, according to the town report.

In its proposed plan to reduce dust from road sanding, the town would ask the California Department of Transportation to modify its operations on Interstate 80 and local highways, according to the Truckee Air Quality Management Plan Control Strategy.

Typically, Town of Truckee road crews put down about 1,000 tons of sand on local roads a year, depending on conditions, said Dan Wilkins, town engineer and public works director.

"The sand is swept up between storms, and we typically spend one-and-a-half months to two months in the spring on comprehensive cleanup," Wilkins said.

Between 75 and 80 percent of the sand is recaptured, then hauled to either Teichert Aggregates for recycling or to Tahoe Sierra Disposal site for landfill sealing, he said.

Wilkins said recaptured sand can't be used on roads again because it becomes too fine to be effective.

The town has also attempted to reduce its use of sand in the winter by limiting it to school bus routes and applying sand only when needed, Wilkins said.

The equipment used also has filters to reduce the amount of course dust escaping into the air, he said.

"Our current practice is to only use as much as necessary, clean it up as soon as possible, and use the best equipment," Wilkins said.

The threat to air quality in mountain regions posed by road sanding can be glimpsed by the enormous amount of sand that Caltrans uses to keep local highways open during the snow season. In 2005-06, state transportation crews put down 24,450 tons of sand along Interstate 80 alone from Auburn to the state line of Nevada, including on and off ramps and overpasses, said Caltrans Spokesperson Shelly Chernicki.

While Caltrans keeps tabs on how much sand it recaptures in the Tahoe Basin, it only has figures for what it removed from drainage infrastructure on I-80, Chernicki said. In 2005-06, that amounted to 434 tons.

In the same period, Caltrans used 9,502 tons of sand in the Tahoe Basin on Highways 28, 50, 89 and 267, Chernicki said. Of that, the agency recovered 53 percent, or 5,053 tons, although late spring storms hindered the effort.

"In past years we've done between 80, 90 and 100 percent recovery," Chernicki said. "But with those storms, we lost two months of work."

She expects the recovery rate will be higher for the winter of 2006-07. Caltrans uses both "dustless" sweepers and six Vactor trucks, which vacuum up road sand, to reduce dust in the air, she said. The state agency also tries to offset any air quality impacts by using the highest grade (lowest dust) sand in the area, she added.

"It's a balancing act, we are trying to deal with water quality, trying to deal with air quality, and at the same time trying to keep the roads open and safe for motorists and commerce," Chernicki said.