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Espoo to pilot first gravel recycling effort

Recycling the sand and grit used to help with slippery roads is possible and ecological, says Espoo's city road manager.

Kasa hiekoitushiekkaa kadun kulmassa.
Mounds of gravel by the roadside are a common sight every spring in Finland. Image: Marko Väänänen / Yle

Each winter the cities of Finland sprinkle tens of thousands of tonnes of gravel onto their roads to keep cars and people safer. However, all that grit goes to waste as there are almost no recycling methods in place in the country.

Road manager Teemu Uusikauppila for the southern city of Espoo said that it used 35,000 tonnes of crushed stone in its anti-skid efforts in 2018. But next winter the city has plans to take back some of that stone, to rinse it and reuse it.

The first-time programme means to recycle 10-15 percent of the annually used anti-skid gravel. Even this scale is unprecedented, said Uusikauppila. The only other attempt to clean and recycle gravel was in 2016, and not enough was produced with the process at the time to warrant reuse.

Uusikauppila said Espoo does not expect to make gains or savings the first year.

"Cleaning and recycling anti-skid crushed stone is about as expensive as buying new gravel," he said. "This is something that needs to be seen as climate action, pure and simple."

Uusikauppila said recycling the gravel is environmental because cities will mine less natural granite and rock, and CO2 emissions will decrease as far less grit will need to be transported via truck. The same anti-skid gravel could even be used several years in a row.

"I believe Espoo can show the way in this," said Uusikauppila.

Oulu sand ends up in construction

In the northern city of Oulu, a type of sieved natural gravel is used that does not contain sharp stones. This material is often referred to as anti-skid sand, even though it is not produced by natural erosion.

Oulu gathers up this sand every year, but instead of recycling it for the same purpose, the material is used for other useful purposes.

"The sand we've collected this past winter will be taken to a snow-dumping site," said Oulu maintenance manager Kai Mäenpää. "We fix bad angles in the snow heaps, and we're able to direct the runoff in the right direction."

Oulu has also used anti-skid sand to build noise barriers and jogging tracks. Using the sand for anything else is still problematic.

"The sand would have to be cleaned before it could be reused, as it may contain impurities such as heavy metals. The sand may also be crushed further when recycled, causing more dust to accumulate in the air," he explained.

Mäenpää said his city would be following Espoo's pilot programme very closely.

"We have to use natural resources sensibly," he said. "Cleaned, recycled anti-skid sand may be the future."

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