Metrostav Norge has established large-scale treatment plants to reduce the environmental impact of nitrogen run-off during tunnel construction.
The Norwegian company has set up the plants on the E134 Røldal–Seljestad project to treat the run-off water from blasted rock from the 12.4km long tunnel between Røldal and Seljestad. The nitrogen is a residue from explosives.
The treatment plants use a nature-based biofilter that consists of approximately 90% birch chips and 10% shell sand. The method has previously been tested by Statens Vegvesen – Norwegian Public Roads Administration and NIBIO Norwegian Institute of Bioeconomy Research in connection with the E16 Bjørum–Skaret project, with promising results.
“On the E134 Røldal–Seljestad, we have taken the solution a step further and scaled it up to test the method under real construction conditions and in full scale. The facility will provide valuable experience and knowledge about how nature-based treatment methods can be used to reduce nitrogen run-off from large tunnel and infrastructure projects,” the company says.
The single-tube Røldal Tunnel will be Norway’s third longest road tunnel. Metrostav began construction last year and is due to complete works in 2030.
