Global warming may alter road salt routine

Salting and sanding roads in the Northeast is a routine part of winter, but changes in climate patterns caused by global warming may alter the established policies on snow removal, incurring higher costs and influencing road safety, according to a Penn State geographer.

"I am working with the Consortium for Atlantic Regional Assessment on a case study in New York State's Adirondack Park that investigates many aspects of climate change and land use change on local communities," said Tawan Banchuen, graduate student in geography. "My project focuses on climate change's effect on winter road maintenance including environmental and economic impacts."

Adirondack Park is six million acres in Upstate New York, about the size of Vermont, occupied by 130,000 people year round, but visited by several million each year. The area encompasses Lake Placid, home of two Olympics, and many other small towns and is the largest protected area in the United States. Forty percent of the area is preserved, and 52 percent has been harvested and is currently managed.

Banchuen is currently looking at an area in the Park near Whiteface Mountain. He is investigating the use of salt and sand on both federal highways and local roads and tracking where the sand and salt end up. Banchuen would eventually like to model the climate change and consequent precipitation changes to see how it affects the amounts of salt and sand needed and how that affects the environment and economy.

"After the 1980 Lake Placid Olympics, the communities in the park promised to follow a bare pavement policy in winter," Banchuen told attendees at the American Association of Geographers meeting on April 6 in Denver.

"Typically, state roads use mostly salt and local and town roads use sand," said Banchuen. "Salt is more expensive."

A previous study of four small streams in the park that feed into Rich Lake, found a significant elevation in chlorine downstream from the road. These elevated levels remained for four to six months after the last application.

Unfortunately, salt has many potential impacts on lakes. Increased salt concentrations can cause the lake to stratify into lighter and denser layers. While this often happens in the summer with temperature gradients, the salt could prevent the water from remixing in the fall. Circulation would stop or slow, and oxygen would not mix into the lower layers of the lake. With oxygen depletion come fish kills and releases of heavy metals in the sediment. Saltier water would also favor salt tolerant plants and animals and decrease the diversity in the lake.

Outside the lake, increased road salt can kill vegetation at roadsides. Road salt damages automobile undercarriages and bodies. Salt can also seep into the groundwater drinking supply.

Sand increases the load of suspended particles in streams and lakes. It also creates a clean-up problem on the sides of the road.

"Currently, in one county in the Adirondacks, half the road maintenance budget is spent on clearing the roads and making them safe," said Banchuen. "The rest can only repair half the damaged roads in the area."

A warmer climate does not necessarily mean less road salt use. Most researchers who look at warming agree that a warmer global climate will bring more precipitation to the area of the Adirondacks. The question is, will that precipitation fall as snow, mixed snow and sleet, sleet, freezing rain or rain?

"If the precipitation tends toward more sleet and freezing rain, then more salt and sand will be needed to make the roads safe," says Banchuen. "But, fewer days of snow might mean less ski traffic in the park and a depressed winter economy. Policy makers will need to adapt to the changes and make decisions that minimize the impacts of the changes."

Eventually the Penn State researcher will look at how storm tracks, population, elevation, traffic patterns and other variables influence the use of salt and sand and how that will affect the economy of the area.

This research was funded by EPA.


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