The streets and sidewalks of Polish cities have been covered with a thick layer of snow. The standard solutions - spreading salt and sand, plows and shovels - went into action. Some cities have decided to seize the opportunity and introduce experimental methods of maintaining sidewalks during winter. They are using coffee grounds for this purpose. However, the use of this waste is controversial.
More and more Polish cities are giving up spreading salt on roads and sidewalks. This solution, although the most effective in the fight against snow and ice, is tragic in its consequences for plants and animals. So what are the other options? According to the October 27, 2005 Regulation of the Minister of the Environment, non-chemical agents such as sand, natural or artificial aggregate, chemical agents in solid form and in wetted form (sodium chloride, magnesium chloride, calcium chloride) are allowed. The regulation also allows mixtures of these agents.
The most common substitutes
photo: the Urban Greenery Management Board of Krakow
And so the most common solution besides salt is to cover sidewalks with sand, which improves friction, but heavily pollutes public spaces and clogs sewers. Visible long after the melt, it is impossible to reuse. Chemical substitutes for road salt, on the other hand, are more expensive than it. Magnesium chloride is much more efficient and works at lower temperatures (rock salt only to about -10 degrees). This agent does not cause the phenomenon of physiological drought, which is the most acute effect of soil salinity.
Reuse
Scandinavian countries have long used a very simple and ecological solution. Instead of fighting snow by melting it, streets and sidewalks there are spread with granite gravel. This is collected after the melt and reused the following season. The same can be done with expanded clay. The lightweight and frost-resistant ceramic aggregate made of baked clay is safe for the environment and does not harm plants or animals. The lightweight sprinkle can be easily removed from the road and reused a year later.
Garbage for sidewalks
photo by the Board of Urban Greenery in Krakow
In several cities in Scandinavia and Lviv, the idea of using for winter maintenance of sidewalks... waste is being implemented on a wider scale. We are talking about coffee grounds, which are collected from local coffee shops and dumped on the sidewalks. Gaining popularity on the Internet, the idea has been picked up by Krakow's Urban Greenery Management, which is testing the solution in several locations in the city. Since the grounds, do not meet the requirements of the ordinance, they cannot be used on roads and sidewalks adjacent to them. Officials therefore chose Wajda Square in Planty and the alleys in Polish Aviators Park for this purpose. The sites were marked accordingly, and local cafes were invited to participate in the project.
Useful or harmful?
As the originators of this solution argue, grounds are also used in gardening for composting and watering plants, which is supposed to influence their better growth. ZZM is planning observations in this regard in the spring. As it turns out, however, not every concentration of coffee in the soil is inert or beneficial to plants and animals. As Przemysław Poszwa, author of the eco-logicznie.com blog, calculates, there are a number of doubts that should absolutely be checked before introducing the solution on a large scale.
photo: Urban Greenery Management in Krakow
First of all, adding coffee grounds to the soil in improper proportions causes a significant decrease in plant growth. This agent can act as a fertilizer, but in strictly defined proportions and depending on the type of plant. The antibacterial properties of grounds cause a toxic effect on the soil microflora. Acting as a bactericide and fungicide, coffee can significantly reduce the biodiversity of ground cover in parks and squares. The soil-fertilizing population of earthworms, whose mortality increased in the studies conducted, may have a similar effect after increasing the proportion of coffee in the compost mass. Coffee can also exert toxic effects after flowing into watercourses or ponds, causing inhibition of biofilm growth and disrupting ecosystems. This is also a side effect that threatens the city's sewer system.
Caution advised
The reactions described, however, are effects observed mainly under laboratory test conditions; the grounds are unlikely to have been tested to date at the urban scale and concentration that would be associated with winter maintenance of sidewalks. Some of the side effects require a high concentration of coffee, which is likely to be difficult to achieve with such a diffuse effect. Implementing the use of grounds, however, will require adequate research and preparation. A pilot similar to Krakow's has also been started in Warsaw's Ursynów district.
