Snow can actually be considered waste. What we think about is of course not the white fresh snow that had fallen in the mountains without snow soiled in urban environments, and which must be disposed of in an environmentally sound manner. Snow falling on the streets and squares become contaminated by road salt , oils, heavy metals and other substances.
Such masses of snow can be added at an approved landfill site to prevent spreading contamination, but during snowy winters landfill capacity can be quickly exceeded. Using a landfill further away is perhaps possible, but it increases both the transport cost and environmental impact of the trucks. To dump snow into a stream is technically possible and still relatively common. Under environmental law, this is not allowed because the pollution can affect aquatic plants and animals. Exemptions from the ban, however, is common and Stockholm , Gothenburg, and a number of other cities have temporary permission to tip hundreds of thousands of cubic meters of snow in nearby streams.
Waivers go out for these cities and many municipalities must now quickly find a better solution than to dump the snow into a water body. The same problems exist in Norway and NCC Norway, with Norwegian researchers have developed a new method to melt and “detoxify” contaminated snow. The first facility is now in place in Oslo and NCC won in 2013 the Norwegian construction industry innovation award for the snow melting system, called SS “Terje.”
SS “Terje” does the job
“We have developed a process that should interest the Northern European cities who have trouble handling large amounts of snow,” says Terje Myrhaug, head designer at NCC. “We expect not only a cleaner marine basin but also a cleaner air and groundwater in Oslo. In addition, we lower carbon emissions from the transportation of snow. NCC now has an agreement with the Oslo municipality for eight years to take care of the snow accumulation on the city gates. Snösmältaren SS ” Terje” can take care of all the snow that collects in the city and the capacity is about 500 m3 per hour, “continues Myrhaug.
Snösmältaren SS ” Terje” sits on a barge at Akers berth in the Norwegian capital and the process can be likened to a large mixer:
- The truck dumps snow from the dock down to the barge where larger items such as bicycles and shopping carts are sorted out in a network. The snow is then passed on to a mixing chamber.
- While stirring, finely crushed snow and the salty and hot water extracted from the Oslofjord helps the snow and ice melt faster. The heat in the seawater is obviously not very warm in the winter but it has a higher temperature than the snow. The temperature of the water used is never less than 4 °C.
- The melt water is then taken to a mechanical washing plant where it is cleaned from coarse impurities like oils, sand and gravel. In the last process, the water flows through a filter that removes the most finely divided particles. Then it is led it into the Oslo Fjord and the temperature is now about three degrees lower than in the water that was pumped into the process.
“We do regular chemical analyses of incoming and outgoing water to monitor the purification processes. The impurities are trapped in the different filter stages and are taken care of as hazardous waste,” says Myrhaug.
Innovation Prize and international acclaim
The Norwegian Innovation Award is presented to a company, organization, agency or person who has made a special effort in the form of innovation related to processes, products or services, and innovation and value creation for the benefit of the community and the construction industry.
The jury notes:
“The winner will strengthen Norwegian building tradition. The innovation is ingenious and very energy smart. It meets the stringent environmental requirements both nationally and locally and is simultaneously efficient, reduces the need for transport and allows for reuse of materials. The plant reduces annual CO2 emissions and dust from the hundreds of tons of snow, and also uses the large amount of energy that occurs naturally in seawater. The innovation has received considerable attention abroad.”
“It is an honour for NCC to receive this innovation award. We contribute to a better environment in Oslo with our snow melting plant and a time may come when we effectively remove snow from the streets, “concludes Chief Engineer Myrhaug .
The article was published in December 2013