The use of waste incineration has been a trend to process waste in Finland. The amount of waste delivered to landfills has diminished and ash processing plants have replaced the open landfills. After the removal of metals the ash can be reused as gravel. Fresh gravel is cheaper and usually it has better availability then the recycled materials such as incineration ash.
There is also environmental concern about the usage of the ash in excavations. The metals and minerals can dissolve to the local waters due this there are restrictions to the usage of the material. Landfills and waste management companies are using the ash in their own local excavations.
There are pilot programs of the usage of ash. Route 7 from Helsinki to the Russian frontier has multiple sound barriers filled with incineration ash. Sound barrier 421 contains 6400 m3 of bottom ash from waste incineration. The rain water that flows thru the barrier is collected to a drain where it is directed to the baltic sea. The ash used in the barriers is from the local incineration plants and power plants. The furthest plant is in Lahti, 100km away from the site.
My documentary project is about the effects of waste incineration and the reuse of ash materials in Finland.