Examining the effects of road treatments on the environment | SummitDaily.com
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Examining the effects of road treatments on the environment

HIGH COUNTRY – The number of orange-needled trees along Colorado’s High Country roadways seems to be on the rise, and everyone has a theory as to why.

Some blame magnesium chloride, the popular de-icer used to keep the roads open to traffic.

Others blame the sand that maintenance crews have dumped on the roads for decades on end.



Some say it’s pine beetle infestations in the old stands of lodgepole pines.

Some say it’s smog from the increasing numbers of vehicles traveling through the state.



And many others wonder what toll the cumulative effects of salt, sand and chemicals that have been dumped on Colorado’s roads will take on wildlife, water and air quality – even on human health.

Salt and sand

Scientists don’t have to look far to see the impact of salt and sand on water and air quality in Colorado.

Sand, while providing great traction on icy, snowy roads, is subsequently washed into creeks, filling streambeds and changing the velocity of the water. That affects what insects are likely to hover nearby – and can determine if fish will continue to swim there.

Such is the case at the headwaters of Black Gore Creek at the top of Vail Pass, where decades of sand deposits have threatened the viability of the Gold Medal fishing waters below. Currently, a multimillion-dollar cleanup is under way to try to restore the waters to their original condition. The same situation is taking place at the headwaters of Straight Creek, which starts near the Eisenhower Tunnel and flows through Dillon Valley to Dillon Reservoir.

Sand is ground up under car tires and becomes airborne. In the 1980s, sand and, to a lesser extent, vehicle emissions and woodstove smoke were blamed for the constant copper-colored cloud that hovered over Denver, making it one of the most polluted cities in the nation.

Switching from sand to mag chloride, improving vehicle emissions standards and curtailing the use of woodstoves and wood-burning fireplaces have brought Denver into compliance with federal air quality standards and won the city kudos from industry experts.

“All that sand we were putting down was of great concern to us environmentally,” said CDOT superintendent Ed Fink. Everybody’s worried about mag chloride, but mag chloride is not going to hurt the environment. We’ve studied it. Everything we have ever done has said get away from sand and go to mag chloride. It’s far, far better.”

Volcanic cinders also pose a potential air pollution problem, said Ray Merry, environmental health director for the town of Avon. There, crews apply cinders as it snows, and, when the streets are dry, sweep them up before they can become airborne. The town gets its cinders from a mine in northwest Colorado.

According to Summit County environmental health director Jim Rada, particulate matter less than 10 microns in size – called PM 10 – poses a health risk. Larger particulates can’t become airborne, he said, and settle on the ground.

That’s why most localities and state transportation departments started street-sweeping programs.

“But it’s a difficult balancing act,” Rada said. “It’s de-icing and traction control, or it’s the environment.”

John McCarty, a landscape architect with OTAK, a landscaping, civil engineering and planning firm in Carbondale, said his crews have noticed the impacts of volcanic cinders or coated gravel on roadside plants.

The darker-colored cinders and gravel absorb more heat from the sun, and, while the plants are able to grow all spring, the higher temperatures in late summer tend to kill them.

Chemicals

Chemical de-icers are a little harder to pin down.

“It’s hard to trace where they go,” McCarty said. “The abrasive stuff, you can create containment areas to intercept and control where it goes.”

McCarty, who was among the many landscape architects who worked on Glenwood Canyon’s highway reconstruction project, said all the studies he’s read are inconclusive.

But he’s sure of one thing: Salt kills plant life. And chloride is a salt.

“Sodium chloride (table salt) affects the structural integrity of soils,” he said. “The sodium attaches to the nutrients and won’t release, so there’s no exchange between the plant and the nutrient.”

Chloride, he said, coats and desiccates pine needles. But magnesium is a nutrient in the soil and is more of an asset than a hindrance.

Merry said mag chloride might be the lesser of many evils, particularly rock salt that is mixed with sand.

“From a study standpoint, from an environmental impact standpoint, we know sand and salt is bad for our streams,” he said. “Nothing chokes out aquatic habitat worse than that.”

But mag chloride?

“I hesitate to jump to conclusions,” Merry said. “I wouldn’t sit back and say the stuff’s completely safe. All we’ve seen so far, though, is that mag chloride is better than sand and salt, but I don’t think we’re done yet. We want to use alternative products that are more environmentally friendly, and we want to make sure what’s in it doesn’t have trace contaminants. We won’t realize the long-term impacts until the long term. I don’t know the answer.”

“I could be told that’s something environmentally friendly and find out 10 years from now it isn’t,” Avon Town Manager Larry Brooks said. “The main thing we’re after is, once we’ve been as conservative as we can, we must make it safe for the public.”

Transportation department studies conducted by numerous states and other studies published by college researchers – some of which are funded by state transportation departments – indicate mag chloride doesn’t harm wildlife. Two Colorado studies show mag chloride won’t hurt boreal toads or native trout – unless they are subjected to high concentrations of the chemical.

A study conducted in Canada says heavy metals used to prevent corrosion settle to lake bottoms and suffocate the microorganisms that live there.

Summit County’s Rada said some magnesium chloride mixtures have been found to be high in phosphorus, which concerns those in charge of keeping Dillon Reservoir’s water clear. Phosphorus, which is found in sanitation district effluent and fertilizers, encourages algae growth, which uses the oxygen fish need to survive.

Summit Water Quality Commissioners, however, track phosphorus levels by following building trends and say Dillon Reservoir is well below the allowable levels for phosphorus.

The ultimate solution, experts agree, could be in using the chemicals properly, However, Merry said, public perception – say, the hatred of mag chloride – can drive public policy, and that might not always lead to the best solution.

“What makes sense is to be cautiously optimistic about de-icing compounds and always use a safe product responsibly,” he said. “There will be trends, and there will be public outcry that says we want safe roads, we want the environment protected, and we want vehicles protected.”

McCarty agrees.

“We demand lower taxes and a higher accountability of government for environmental stewardship,” he said. “People like to hammer on CDOT because trees are dying along the sides of the roads. We have to either not expect roads to be 100 percent clear after a snowstorm or put more money into the kitty to deal with it in an alternate manner.”

Jane Stebbins can be reached at (970) 668-3998 ext. 228 or jstebbins@summitdaily.com.


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